US20180169747A1

US20180169747A1 - Sprue System for a Diecasting Die

Info

Publication number: US20180169747A1
Application number: US15/579,731
Authority: US
Inventors: Marc Nowak; Norbert Erhard; Ronny Aspacher
Original assignee: Oskar Frech GmbH and Co KG
Current assignee: Oskar Frech GmbH and Co KG
Priority date: 2015-06-05
Filing date: 2016-06-02
Publication date: 2018-06-21
Also published as: ES2929397T3; WO2016193397A1; DE102015210403A1; JP6791884B2; HK1245717A1; PL3302851T3; JP2018516176A; EP3302851B1; CN107848026A; EP3302851A1; PT3302851T

Abstract

A sprue system for a diecasting die includes at least one runner channel, which extends from an entry-side sprue mouth opening to an exit-side sprue opening, which opens into a die cavity of the diecasting die that is formed between a fixed die half and a movable die half or into a gate region arranged upstream thereof. The runner channel has a geometrically and/or thermally defined parting region upstream of the sprue opening and downstream of the sprue mouth opening. The runner channel has a bend or kink in the parting region and/or a heating device is assigned to a runner channel portion between the parting region and the exit-side sprue opening and/or a heating device is assigned to a runner channel portion adjoining the parting region upstream and narrowing conically toward the parting region and/or a region of the movable die half opposite the sprue opening has a cooling channel structure.

Description

BACKGROUND AND SUMMARY OF THE INVENTION

The invention relates to a sprue system for a diecasting die, i.e. a diecasting mould, wherein the sprue system includes at least one runner channel, which extends from an entry-side sprue mouth opening to an exit-side sprue opening, which opens into a die cavity that is formed between a fixed die half and a movable die half or into a gate region arranged upstream thereof. In particular, it may be a so-called hot runner sprue system. The entry-side sprue mouth opening may in particular be configured in such a way that a mouthpiece nozzle or the like of an upstream part of the casting system can be placed against it.
The applicant has on the market a hot runner sprue system known as the Frech Runner System or Frech Gating System (FGS) for diecasting dies, as also mentioned for example in the article Druckgiessen [diecasting] by L. H. Kallien and C. Böhnlein in the journal Gießerei 96, July 2009, pages 18-26. Hot runner sprue systems generally have the advantage over other conventional sprue systems that the proportionate amount of molten material that is accounted for by the so-called sprue or gate or the sprue or gate region upstream of the die cavity and has to be detached from the cast product can be reduced significantly. Moreover, the proportionate amount of air in the casting system can be kept down, which makes it possible to cast parts with a correspondingly low porosity, and the thermal efficiency is improved because the heat losses up to the cavity in the die are less, and consequently the melt has to be overheated less to compensate for the losses. There is an increase in the productivity of the machine because the sprue is much smaller and less bulky.
The applicant's patent specifications EP 1 201 335 B1 and EP 1 997 571 B1 disclose hot runner sprue systems that are for example of a comb or fan sprue type or have sprue block units with integrated melt runner heating that can be inserted independently into a respective casting die.
It is known to prevent liquid molten material from escaping when the die is opened by means of a mechanical closure system. However, specifically also when they are used in metal diecasting, such closure systems are relatively susceptible to wear and tend to leak. It has therefore also already been variously proposed to prevent this undesired escape of molten material by forming a plug of solidified molten material in the region of the sprue mouth opening of the sprue system or in the region of a mouthpiece nozzle placed against it or of an upstream casting chamber outlet channel, see for example the patent specification DE 100 64 300 C1, the laid-open application WO 2007/028265 A2 and the already mentioned patent specification EP 1 201 335 B1.
In the patent specification DE 196 11 267 C1, a sprue bush which is inserted into a tool part and held on it and has a through-channel for molten metal is disclosed for use on a hot-chamber metal diecasting machine. The sprue bush is designed in particular for use on a zinc diecasting machine. The through-channel is in connection on the one hand with a metal feeding device and on the other hand with a cavity of the tool and is formed cylindrically over much of its length from the feed opening to just before the opening into the cavity, it then having a constriction and, following that, a conical widening up to the opening entering the cavity. The sprue bush has electrical heating over virtually the entire length of the cylindrical form of the channel and a cooling zone in the region of the constriction. The cooling zone is formed by an air gap introduced into the sprue bush. The electrical heating of the cylindrical form of the channel ends at a distance before a conically narrowing entry region of the constriction.
There has recently been an increase in the demand for diecasting techniques in a relatively high temperature range of up to about 700° C. or 750° C. With this increased temperature, the risk of undesired oxide formation also increases, in particular in outlet opening regions of the pouring system, where the molten material can come into contact with oxygen from the air. Among other things, this also means that there are corresponding requirements for sprue systems that operate on the basis of the hot runner technique.
It is an object of the invention to provide a sprue system of the type mentioned at the beginning that in terms of the process is also dependably suitable for relatively high diecasting temperatures and, if required, can be implemented as a hot runner sprue system.
The invention achieves this and other objects by providing a sprue system where the runner channel has a geometrically and/or thermally defined parting region, which is formed upstream of the sprue opening and downstream of the sprue mouth opening in the direction of flow of the molten material to be cast. This means that the parting region is at a certain, predetermined distance both from the exit-side sprue opening and from the entry-side sprue mouth opening of the runner channel. The parting region should be understood here as meaning the region of the runner channel that is formed as a predetermined location for the detachment or breaking away of the molten material that has solidified or partially solidified on the die side from the still liquid or still less-solidified molten material in the runner channel when the die is opened. This detachment may be an actual breaking away of solid-solid phases of the molten material or a melting away or pulling away, in which the solid part of the molten material separates from the liquid phase in that melt entrained on its surface solidifies and the liquid part remains in the runner channel on account of surface tension.
This predetermined breaking location is geometrically defined, i.e. by a corresponding geometrical design of the profile of the runner channel, and/or thermally defined, i.e. by a corresponding thermal design of the profile of the runner channel. A person skilled in the art understands this as requiring that the runner channel is designed in such a way that the metal melt downstream of the parting region solidifies more easily or more quickly than upstream of the parting region, so that, when the die is opened, the molten material that has already solidified or partially solidified to a relatively great extent downstream of the parting region is pulled out of the runner channel by the opening movement of the movable die half as a component part that is attached to the cast product, and is thereby detached or broken away from the molten material that is still liquid or at most partially solidified to a lesser extent upstream of the parting region. Aware of this requirement, a person skilled in the art is familiar with suitable geometrical and thermal measures for implementing the parting region, so that he can provide suitable channel configurations, if appropriate by using simple trials and/or computational simulations, depending on the configuration otherwise of the diecasting die and depending on the molten material that is used. Coming into consideration as molten materials are both conventional molten salts and conventional molten metal alloys, in particular nonferrous alloys on the basis of magnesium, aluminum, zinc, tin, lead or brass as the respective main constituent.
The definite setting of the parting region ensures according to the invention that the solidified or partially solidified melt is reproducibly detached specifically at this location and not randomly somewhere or at varying locations of the runner channel. The sprue system according to the invention does not require a mechanical closure system. The design of the temperature profile along the runner channel, which comprises the thermal definition of the parting region, can also be devised in such a way that it forms a temperature-transient portion of the runner channel from an upstream heated region to a cooled, contour-determining part of the casting die. This can counteract undesired oxide formation and fire hazards, in particular in the case of highly reactive or oxidizing melts.
According to one aspect of the invention, for this purpose the runner channel has a bend or kink in the parting region. This geometrical measure is suitable for assisting the functionally dependable detachment of the molten material specifically in the parting region defined for it.
According to an additional or alternative aspect of the invention, a region of the movable die half opposite the sprue opening of the runner channel has a cooling channel structure. With this thermal measure, the solidification or partial solidification of the molten material in the runner channel downstream of the parting region can be assisted.
According to a further additional or alternative aspect of the invention, a runner channel portion between the parting region and the exit-side sprue opening is assigned a heating device, and/or a runner channel portion adjoining the parting region upstream and narrowing conically toward the parting region is assigned a heating device. As a result, the exit-side part of the runner channel and/or the portion of the runner channel adjoining the parting region upstream and narrowing conically can be actively heated in a controlled manner as and when required. This represents advantageous geometrical-thermal measures for the definition of the parting region at the desired location. The respective heating device may for example be an electrical or inductive heating device known per se, which is arranged in the runner channel itself or outside the same at a sufficiently small radial distance.
In a development of the invention, the runner channel has in the parting region a constriction, from where its through-flow cross section increases downstream and/or upstream. This geometrical measure assists the reliable detachment of the molten material in the parting region. The runner channel may for example be configured in such a way that its through-flow cross section widens from the parting region to the sprue opening, i.e. the through-flow cross section no longer decreases from the parting region to the sprue opening but instead becomes steadily greater or at most remains constant over this portion. This geometrical measure of the runner channel design can facilitate the pulling of the molten material that has solidified or partially solidified to a great extent out of the portion of the runner channel from the parting region to the exit-side sprue opening, and consequently also the detachment of this part of the molten material from the molten material upstream of the parting region. Thus, the runner channel can for example have a profile from the constriction to the pouring opening that widens in the manner of a funnel.
Preferably, the distance of the parting region from the exit-side sprue opening of the runner channel is very small, and in particular much smaller than from the entry-side sprue mouth opening of the runner channel; in the present case, these distances that are referred to should be understood in relation to the length of the flow path of the molten material delivered by the runner channel. This makes allowance for the aim of minimizing the proportionate amount of melt that solidifies as a sprue on the cast part and is removed with it from the die. The system can be constructed in such a compact format that there is scarcely any appreciable solidified runner or sprue on the cast part. Specifically, according to a development of the invention, the parting region is at a distance in front of the sprue opening of between 0.3 times and 3 times a diameter of the runner channel in the parting region, and consequently correspondingly close.
In a development of the invention, a runner channel portion between the parting region and the exit-side sprue opening is assigned a cooling channel structure. Also in this way, the thermal definition of the parting region, and consequently the reliable detachment of the molten material in this region, can be improved further in a specifically intended manner.
In a development of the invention, in a region adjoining the parting region upstream, the runner channel runs at an angle of between 0° and 45°, in particular between 3° and 20°, to the direction of a normal to a parting plane between the fixed die half and the movable die half, to be precise rising in the direction of the parting region. This profile of the runner channel rising in the direction of flow of the melt in this portion can contribute to avoiding an undesired escape of molten material from the runner channel when the die is opened after detachment of the molten material in the parting region. With the system designed in this way, said rising profile of the runner channel is even obtained when the die halves are arranged with a vertically situated parting plane.
In a development of the invention, the sprue system is configured as a hot runner sprue system and comprises in a way known per se a melt manifold block, which on the entry side has the sprue mouth opening, and a sprue block, which adjoins the melt manifold block in the direction of flow and on the exit side has the sprue opening. In this case, the parting region is formed in the portion of the runner channel that runs in the sprue block. The parting region is consequently located at a relatively small distance in front of the parting plane of the fixed die half and the movable die half, close to the gate.
In a development of the invention, the sprue system is configured as a hot runner sprue system, and the at least one runner channel comprises at least two runner channels that are parallel in terms of flow, wherein temperature control means are provided, designed for controlling in an open-loop or closed-loop manner the temperature of the molten material in the parting regions of the runner channels independently of one another to a predeterminable setpoint temperature of between 0.9 times and 1.1 times, in particular between 0.98 times and 1.02 times, a liquidus temperature of the molten material.
With these temperature control means it is possible in a very advantageous way in the case of such a hot runner sprue system with multiple runner channels that are parallel in terms of flow to keep the molten material in the parting region of each runner channel at a desired temperature, which lies in the associated solidifying temperature interval. The individual temperature control of the molten material in each of the parting regions allows to account for any differences in the geometry of the runner channels and different temperature influences specifically for each individual runner channel or parting region, so that the temperature that is optimum for the detachment of the molten material can be set in each of the parting regions, which are spatially separate from one another but are in flow connection with one another by way of the runner channels.
In a refinement of the invention, the temperature control means comprise an open-loop temperature control unit or a closed-loop temperature control unit and, for the respective runner channel, a temperature sensor system between the parting region and the exit-side sprue opening and/or the heating device between the parting region and the exit-side sprue opening and/or the heating device in the runner channel portion adjoining the parting region upstream and/or the cooling channel structure in the region of the movable die half opposite the sprue opening and/or the cooling channel structure between the parting region and the exit-side sprue opening. This represents advantageous variants of the way in which the temperature control means can be implemented.
In a development of the invention, the runner channel portion adjoining the parting region upstream and narrowing conically toward the parting region goes over at an associated transitional location into a cylindrical plunger portion of a constant diameter adjoining upstream. In this case, the axial length of the runner channel portion narrowing conically toward the parting region is less than the axial length of the runner channel portion between the parting region and the exit-side sprue opening, i.e. less than the distance of the parting region from the exit-side sprue opening. This measure can further optimize the profile of the runner channel and the detachment or breaking away of the melt in the runner channel in the parting region.
In a development of the invention, the region of the movable die half that is opposite the sprue opening has a recess or is formed as level. Both configurational variants can advantageously assist the breaking away characteristics of the melt, depending on the particular conditions otherwise of the system.
In a development of the invention, the runner channel portion located between the parting region and the exit-side sprue opening branches into multiple channel branches that are parallel in terms of flow. These lead to associated exit-side sprue opening locations, and from there into associated gate regions or gate cavities. This may be of advantage for corresponding designs of the form that is to be cast, and consequently of the die halves to be used for it.

BRIEF DESCRIPTION OF THE DRAWINGS

Advantageous embodiments of the invention are described below and presented in the drawings, in which

FIG. 1 shows a schematic, partly sectional side view of a part of interest in the present case of a diecasting die,

FIG. 2 shows a view of a detail from FIG. 1 with a runner channel with a parting region that includes a bend/kink,

FIG. 3 shows a schematic sectional view of a part of interest in the present case of a further diecasting die with a runner channel with a geometrically and thermally defined parting region,

FIG. 4 shows a view corresponding to FIG. 3 for a variant with an additional possibility for cooling and heating an exit-side runner channel portion,

FIG. 5 shows a view corresponding to FIG. 4 for a variant with a cylindrical runner channel portion of a constant diameter,

FIG. 6 shows a view corresponding to FIG. 5 for a variant with a flat design of the region of a movable die half opposite a sprue opening of the runner channel,

FIG. 7 shows a view corresponding to FIG. 6 for a variant with a modified heating/cooling arrangement,

FIG. 8 shows a view corresponding to FIG. 7 for a variant with a branching runner channel portion between the parting region and the exit-side sprue opening,

FIG. 9 shows a sectional view along a line IX-IX of FIG. 8,

FIG. 10 shows a view corresponding to FIG. 8 for a further variant with a branching runner channel portion between the parting region and the exit-side sprue opening and

FIG. 11 shows a sectional view along a line XI-XI of FIG. 10.

DETAILED DESCRIPTION OF THE DRAWINGS

A part shown in FIG. 1 of a diecasting die, as is suitable in particular for the diecasting of salts and metals, for example magnesium, aluminum, zinc, tin, lead and brass, includes in a way that is conventional per se a fixed die half 1 and a movable die half 3, which is movable with respect to the fixed half perpendicularly to a parting plane 2. For this purpose, the fixed die half 1 is clamped, for example in a conventional way, on a fixed platen of a diecasting machine and the movable die half 3 is held on a movable platen of the machine, which is movable with respect to the fixed platen, for which purpose the movable platen is assigned a drive, which is preferably hydraulic. In the parting plane 2, the two die halves 1, 3 butt against one another when the die is closed; for opening the die, the movable die half 3 is moved back in the direction normal to the parting plane 2, i.e. perpendicular thereto. Unless stated otherwise hereinafter, the diecasting die is of any desired conventional construction, as known per se to a person skilled in the art. The diecasting die further includes a sprue system, of which a part that is of interest in the present case can be seen in the partly sectional region of FIG. 1. Otherwise, the sprue system is likewise of a configuration that is known per se to a person skilled in the art.
As can be seen from FIG. 1 and the associated view of a detail of FIG. 2, the sprue system comprises a melt manifold block 4 and, adjoining thereto in the direction of flow, a sprue block 5. The sprue system is preferably of a hot runner type, in which at least the melt manifold block 4 is actively heated, for example by means of an electrical or inductive heating device or by means of a heating fluid that is passed through a heating channel structure of the melt manifold block 4, as known per se. The melt manifold block 4 and the sprue block 5 are incorporated in the fixed die half 1 or are fastened to it.
The sprue system has at least one runner channel 6, which extends from an entry-side sprue mouth opening (not shown) to an exit-side sprue opening 7. With its sprue opening 7, the runner channel 6 opens into a gate region 8 formed between the fixed die half 1 and the movable die half 3, i.e. a gate cavity, which then for its part, as usual, opens into a die cavity (not shown), which mirrors the volume and the contour of the product to be cast.
The runner channel 6 runs from the entry-side sprue mouth opening initially in the melt manifold block 4 and subsequently in the sprue block 5, which reaches up to the die parting plane 2 and forms there the sprue opening 7 of the runner channel 6. The entry-side sprue mouth opening (not shown) forms the inlet for the melt into the melt manifold block 4, against which there can be placed in the usual way an upstream mouthpiece nozzle, which represents the exit-side end of an upstream casting chamber or of a riser leading out of a melt reservoir. It goes without saying that, depending on requirements and the application, the diecasting die may have multiple such melt manifold blocks and/or multiple such sprue blocks, and consequently also multiple such runner channels, for example implemented by a branching runner channel structure. The casting die can then be fed by a multiply distributed sprue block system from a casting container, for example by way of a mouthpiece nozzle of the casting system that is placed against the sprue block system.
As can be seen in particular from FIG. 2, the runner channel 6 has upstream of the sprue opening 7 and downstream of the sprue mouth opening (not shown) an at least geometrically defined parting region 9. The geometrical definition of the parting region 9 includes the formation of a bend 9 a or kink of the runner channel 6, in that a lower part of the channel wall first bends away upward and then goes into the horizontal or takes a slight kink running downward, while in a way corresponding to that an upper part of the channel wall first runs in an upwardly bent-away manner, to then run again with a smaller upward component as far as the sprue opening 7. Altogether, in this way an approximately S-shaped profile of the runner channel 6 is provided, as is clear from a dashed center line 6 c, which approximately reproduces the center line of the cross-sectional profile of the runner channel 6. In alternative implementations, instead of such a bend/kink, the geometrical definition of the parting region may include a less strong curvature and/or a cross-sectional narrowing of the runner channel; in particular, the kink need not be implemented with sharp edges as in the example shown.
The parting region 9 is located inside the sprue block 5, wherein in the parting region 9 a portion 6 a of the runner channel 6 adjoining upstream goes over into a portion 6 b of the runner channel adjoining downstream. The downstream runner channel portion 6 b ends in the exit-side sprue opening 7 of the runner channel 6, i.e. the length of its flow path defines a predetermined distance that the parting region 9 maintains from the sprue opening 7. In the example shown, this distance is much smaller than the remaining, upstream length of the runner channel 6, and in particular is also less than the remaining length of the runner channel in the sprue block 5. In the example shown, the downstream end portion 6 b of the runner channel 6, which adjoins the parting region 9, has a form that widens in the form of a funnel, i.e. in the manner of a hollow cone, in the direction of the sprue opening 7.
As explained above, the parting region 9 defines the predetermined location for the detachment or breaking away of the solidified or partially solidified molten material when the die is opened after a casting operation. Consequently, the molten material that is present in the downstream end portion 6 b of the runner channel 6 behind the parting region 9 remains on the cast product or the solidified molten material of the sprue or gate region 8, whereas the molten material upstream of the parting region 9 remains in the runner channel 6. The profile of the runner channel end portion 6 b widening in the form of a funnel makes it easier to get the molten material that remains there out of the runner channel 6.
As can also be seen in particular from FIG. 2, the runner channel 6 has in its portion 6 a adjoining the parting region 9 upstream a profile that rises in the direction of melt flow with respect to the die parting plane 2 shown in the vertical position. In this case, the runner channel profile assumes an angle α in this portion 6 a of between about 0° and about 45°, preferably between about 3° and about 20°, in relation to the direction normal to the parting plane 2. This contributes to avoiding an undesired escape of for instance still liquid or viscous molten material from the runner channel 6 when the die is opened. It may also be provided that the fixed die half 1, and consequently the parting plane 2, is arranged inclined with respect to the vertical, so that the runner channel 6 rises by a corresponding additional amount in the direction of melt flow.
If required, the parting region 9 may additionally be thermally defined, i.e. the temperature profile along the runner channel 6 may be influenced by active cooling and/or heating temperature-control measures to the extent that the point-precise detachment of the molten material in the parting region 9 is assisted, otherwise provided by the geometrical definition by means of the bend/kink 9 a. As a thermal measure, the sprue block 5 may form a region that is transient with respect to the temperature between the heated melt manifold block 4 on the one hand and the cooled die cavity or gate cavity 8 on the other hand, which is not actively heated, or if at all upstream of the parting region 9, and not actively cooled, or only in the region downstream of the parting region 9. Alternatively, it may be envisaged to heat the runner channel portion in the sprue block 5 according to a predeterminable temperature profile, wherein the temperature in the sprue block is kept lower than in the melt manifold block and/or is set to decrease gradually in the direction of melt flow.
FIG. 3 shows a further exemplary embodiment of the invention, once again only schematically with the components thereof that are of interest in the present case, while the rest of the construction of the diecasting die may correspond to that according to FIGS. 1 and 2 and the explanations of it given above. For easier understanding, designations with the same numbers have been chosen in FIG. 3 for elements that are functionally equivalent but not necessarily identical, so that to this extent reference can additionally be made to the explanations above with respect to FIGS. 1 and 2.
In the case of the diecasting die from FIG. 3, the sprue system includes a runner channel 6′ with a parting region 9′, which is geometrically defined by a constriction 9′a of the runner channel 6′. From this constriction 9′, the channel cross section respectively widens in the form of a funnel or hollow cone both in the runner channel portion 6′a adjoining upstream and in the runner channel portion 6′b adjoining downstream. As mentioned above with respect to the exemplary embodiment of FIGS. 1 and 2, here too a distance A that the parting region 9′ maintains from the sprue opening 7′ is much smaller than the remaining, upstream length of the runner channel 6′, and in particular also less than the remaining length of the runner channel in an associated sprue block 5′. Specifically, in advantageous embodiments this distance A is between 0.3 times and 3 times a diameter D of the runner channel 6′ in the parting region 9′.
In addition, the parting region 9′ is thermally defined in that the runner channel portion 6′b adjoining the parting region 9′ downstream remains unheated, while the runner channel portion 6′a adjoining the parting region 9′ upstream is assigned a heating device 10, with which the molten material in this runner channel portion 6′a can be actively heated up to the parting region 9′, for example adjoining in the direction of melt flow a likewise actively heated melt manifold block. The heating device 10 may be of any type known per se for this purpose to a person skilled in the art, for example in the form of an electrical or inductive heating device, which may be arranged in the runner channel 6′ itself or, as shown, in a region of the sprue block 5′ surrounding it at a small radial distance. Alternatively, heating by a heating fluid is possible, for which a region radially surrounding the runner channel portion 6′a concerned is provided with a corresponding fluid channel structure. The heating of the melt in the runner channel portion 6′a adjoining the parting region 9′ upstream, while at the same time there is no heating of the runner channel portion 6′b downstream of the parting region 9′, can in conjunction with the geometrical design of the constriction assist and ensure the reliable detachment of the molten material dependably in terms of the process in the parting region 9′ configured for this purpose.
As a further thermal measure, the sprue system according to FIG. 3 includes a cooling channel structure 11 in a region 17 of the movable die half 3′ opposite the sprue opening 7′, wherein in the example shown this region 17 has a recess, and is correspondingly depressed. The recess may for example be in the form of a cup, while apart from a round cross-sectional form various other cross-sectional forms are possible, for example oval or star-shaped. By means of this cooling channel structure 11, the molten material in the sprue/gate region 8′ leading to a die cavity 12, and in particular in the part of the gate region 8′ directly adjoining the sprue opening 7′ of the runner channel 6′, can be actively cooled. This assists the cooling, and consequently the solidification or partial solidification, of the molten material in the end runner channel portion 6′b downstream of the parting region 9′, while at the same time the molten material in the runner channel portion 6′a adjoining the parting region 9′ upstream can be hindered from solidifying by the heating device 10. As a result, the molten material reliably breaks away at the parting region 9′ when the die is opened.
In the case of a configurational variant shown in FIG. 4, in addition to the exemplary embodiment of FIG. 3, the runner channel portion 6′b between the parting region 9′ and the exit-side sprue opening 7′ is assigned an active cooling device in the form of a cooling channel structure 13 and an active heating device 14. Like the heating device 10, the heating device 14 may be of any type known per se for this to a person skilled in the art, for example an electrical or inductive heating device, which may be arranged in said channel portion 6′b or, as shown, in a region surrounding it at a small radial distance of the sprue block 5′ or of a sprue insert containing the runner channel 6′. Here too, heating by a heating fluid with a corresponding fluid channel structure is alternatively possible. The cooling channel structure 13 may be fed the same cooling fluid as the cooling channel structure 11 or alternatively some other cooling fluid.
By means of the active cooling device 13 and the active heating device 14 in the portion between the parting region 9′ and the sprue opening 7′, the thermal definition of the parting region 9′ can be further improved in corresponding applications. For example, in a corresponding operating mode, this runner channel portion 6′b may be actively cooled by the cooling device 13, which assists the attachment of the molten material in this portion to the molten material adjoining on the die side, i.e. the sprue of the cast part. This is so because the additional cooling promotes the solidification of the molten material in this channel portion 6′b.
If in corresponding applications the cooling effect provided by the cooling channel structure 11 in the movable die half 3′ is relatively strong and could cause a solidification of the molten material upstream beyond the parting region 9′, that can be counteracted in a corresponding operating mode by the heating device 14 being activated and, as a result, the molten material in the exit-side runner channel portion 6′b being kept at a sufficiently high temperature.
In a further possible operating mode, the cooling device 13 and the heating device 14 of the runner channel portion 6′b could be operated in a clocked manner. This allows a kind of solidification of the molten material in a synchronous cycle to be enforced, which in turn actively assists the process of parting the melt in the parting region 9′.
In further configurational variants that are not shown, the runner channel portion 6′b is only assigned a heating device, without a cooling device, or is only assigned a cooling device, without a heating device. Moreover, in further modified embodiments, the heating device 10 and/or the cooling channel structure 11 may be omitted.
It goes without saying that all of the mentioned cooling and heating devices 10, 11, 13, 14 are assigned an open-loop and/or closed-loop control unit, which suitably activates said cooling/ heating devices 10, 11, 13, 14 in a way corresponding to the respectively desired operating mode.
By way of example of this, represented as an example in FIG. 4 is a closed-loop control unit 15, which activates the heating device 10, the cooling channel structure 11, the cooling channel structure 13 and the heating device 14 by way of corresponding control lines 15 a, 15 b, 15 c, 15 d. In corresponding embodiments, as also shown in FIG. 4, the sprue system additionally includes a temperature sensor system 16 between the parting region 9′ and the exit-side sprue opening 7′. The temperature sensor system 16 is connected by way of an associated sensor line 15 e to the closed-loop control unit 15 and is designed in such a way that it can inform the closed-loop control unit 15 of the temperature conditions in at least part of the runner channel 6′, and in particular in the surroundings upstream and downstream of the parting region 9′. Depending on the system design, the temperature sensor system 16 may include for this purpose one or more temperature sensors arranged one behind the other along the runner channel 6′, specifically in the part shown of the runner channel 6′, which comprises the conically narrowing portion 6′b, the parting region 9′ and the portion between the parting region 9′ and the sprue opening 7′. For example, the heating device 10, the cooling device 11, the cooling device 13 and the heating device 14 may be respectively equipped with one or more temperature sensor elements.
Consequently, in this implementation the sprue system has temperature control means, which may be designed for allowing the temperature of the molten material in the parting region 9′ of the runner channel 6′ to be controlled in an open-loop or closed-loop manner to a predeterminable setpoint temperature, wherein this setpoint temperature is expediently predetermined to a value between 0.9 times and 1.1 times the liquidus temperature of the molten material to be cast, preferably to this liquidus temperature or in a narrow range between 0.98 times and 1.02 times the same.
With these temperature control means, a dedicated temperature control can be achieved for the molten material from the parting region 9′ to the sprue opening 7′. In this way, the temperature of the molten material in the surroundings of the parting region 9′ can be advantageously kept in the solidifying temperature interval of the melt. In this case, the temperature of the melt in the runner channel 6′ may well be chosen to be higher in an inflow portion upstream of the parting region 9′, in order to provide good flow properties for the melt and dependable melt guidance there, which guards against undesired melt-solidifying effects in the runner channel 6′ upstream of the parting region 9′.
The switching on and off of the heating and cooling devices 10, 11, 13, 14 can consequently take place individually by the closed-loop control unit 15, depending on the sensed temperature in the exit-side part of the runner channel 6′. By this specifically intended control of the temperature of the melt in the gate region, it is possible inter alia to prevent that, when the casting die is opened, the molten material remaining in the runner channel 6′ cools down excessively or even solidifies during the removal of the cast part as a consequence of an outflow of heat to the cooled components of the diecasting die. For this purpose, the closed-loop control unit 15 may suitably limit the cooling effect of the cooling device 11, 13 in its influence on the melt supplied at a controlled temperature to the exit-side runner channel portion 6′b up to the parting region 9′, while it can at the same time actively heat the runner channel portion 6′a adjoining the parting region 9′ upstream by means of the heating device 10, and thereby keep its temperature at the liquidus temperature.
In corresponding embodiments of the invention, the sprue system may be configured as a hot runner sprue system with multiple runner channels that are parallel in terms of flow, which open at various locations into the die cavity with spatially separate sprue openings and assigned to which there is respectively a sprue unit of one of the types shown in FIGS. 1 to 4. In particular, each of the runner channels in flow connection with one another in parallel may be equipped with a sprue unit according to FIGS. 3 and 4, which has the temperature control means explained above. In this case, multiple open-loop or closed-loop control units may be provided decentrally or alternatively a common central open-loop or closed-loop control unit may be provided for the cooling and heating devices of the various runner channels. In the case of this multi-channel system design, the temperature of the melt in the exit-side portion can be set optimally for each runner channel individually by the temperature control means with the cooling and/or heating devices that can be separately activated individually for each runner channel in the manner of the cooling and/or heating devices 10, 11, 13, 14 of FIG. 4, so that the desired detachment of the molten material in the parting region 9′ is brought about dependably in terms of the process in each of the runner channels.
For this purpose, it is ensured by the associated open-loop/closed-loop control device, by corresponding activation of the cooling/heating devices that are respectively present, that the parting of the molten material takes place reproducibly at the respective predetermined breaking location with reproducible temperature conditions for each of the multiple spatially separate sprue openings of the various runner channels. Moreover, the sprue openings are thermally made to match one another, so that the parting of the molten material does not have the effect that molten material that has solidified in one of the parting regions of the various runner channels remains behind when the die is opened. Rather, the temperature conditions for each of the multiple spatially separate parting regions are set in such a way that the entire solidified molten material is pulled completely out from the sprue opening at all the parting locations when the casting die is opened. This ensures that in the next casting operation the melt flows by way of the multiple sprue openings into the die cavity in the same flow distribution and reproducibly creates the same flow fronts there.
For this purpose, by means of the cooling and/or heating devices 10, 11, 13, 14 which are assigned to each parting location 9′ of the in this case multiple runner channels 6′ that are parallel in terms of flow, the temperature for each of the parting locations is individually regulated by the associated decentral open-loop/closed-loop control units, or alternatively the central open-loop/closed-loop control unit 15, to the optimum setpoint value, which as mentioned lies approximately at the liquidus temperature of the molten material or in the range of 0.9 times to 1.1 times, preferably 0.98 times to 1.02 times, the same.
It is thereby also taken into account that the temperature in the runner channels is not only dependent on the return flows or reactions of the die cavity or on die cooling devices for the die cavity, but also on the diameter and the geometry of the runner channels. Furthermore, melt energies of various mass flows of the melt can act differently on the thermal efficiency, and consequently also on the temperature conditions of the molten material in the respective parting region when for flow-related reasons it is necessary for filling the die cavity to configure the two or more runner channels that are parallel in terms of flow with a different geometry, such as different diameters, curvatures, kinks, etc. Effects such as these can also be taken into account in a compensating manner by the sprue system according to the invention in the system design with the temperature control means explained, so that also in such implementations of the system the temperature of the melt in each parting region of the multiple runner channels can be set to the optimum setpoint value, or kept at this value, by the individually assigned and activatable cooling/heating devices.
It goes without saying that, as explained above in relation to the examples of FIGS. 3 and 4, the mentioned measures for actively cooling and/or heating the molten material in the sprue/gate cavity, and in particular close to the sprue opening of the runner channel, can also be provided in the case of the sprue system of FIGS. 1 and 2.
FIGS. 5 to 11 illustrate further configurational variants of the exemplary embodiments of FIGS. 3 and 4, the same designations being used for identical and functionally equivalent elements and it being possible to this extent to refer to the explanations given above in relation to FIGS. 3 and 4. Therefore, in relation to these configurational variants, essentially only the differences from the exemplary embodiments of FIGS. 3 and 4 are discussed below.
In the case of the exemplary embodiment of FIG. 5, the runner channel portion 6′a adjoining the parting region 9′ upstream and narrowing conically toward the parting region 9′ goes over at an associated transitional location 18 into a cylindrical runner channel portion 6′d of a constant diameter adjoining upstream. In this case, the runner channel portion 6′a extends in the axial direction over a length L6 a, which is less than the distance A of the parting region 9′ from the exit-side sprue opening 7′, and consequently less than the axial length of the runner channel portion 6′b between the parting region 9′ and the exit-side sprue opening 7′. For the active heating, the cylindrical runner channel portion 6′d is assigned a heating device 10′ by analogy with the heating device 10 of the conically narrowing runner channel portion 6′a in the examples of FIGS. 3 and 4. Optionally, the heating device 10′ may additionally extend in the region of the conically narrowing runner channel portion 6′a and assume there the function of the heating device 10 according to the examples of FIGS. 3 and 4. In corresponding alternative implementations, the runner channel portion 6′b between the parting region 9′ and the exit-side sprue opening 7′ remains without active cooling and heating, or it is assigned the active cooling device 13 and/or the active heating device 14 in a way corresponding to the example of FIG. 4.
FIG. 6 shows a configurational variant which differs from that of FIG. 5 in that the region of the movable die half 3′ opposite the exit-side sprue opening 7′ is formed as a level region 17′ instead of the cup-shaped depression of the region 17 of FIG. 5. The associated cooling channel structure 11 in this case additionally comprises cooling channels directly opposite the exit-side sprue opening 7′.
FIG. 7 shows a configurational variant which differs from the exemplary embodiment of FIG. 6 in that an active heating device 10″ extends both in the cylindrical runner channel portion 6′d and in the conically narrowing runner channel portion 6′a, and assumes the function of the heating devices 10 and 10′ explained above in relation to the exemplary embodiments of FIGS. 4 and 5. Furthermore, in FIG. 7 the active cooling device 13 and the active heating device 14 for the runner channel portion 6′b between the parting region 9′ and the exit-side sprue opening 7′ are explicitly shown, as explained above in relation to the exemplary embodiment of FIG. 4.
FIGS. 8 and 9 show an exemplary embodiment which is similar to that of FIG. 7, while as a difference from the latter the runner channel portion extending from the parting region 9′ to the exit-side sprue opening 7′ branches into multiple channel branches 6′ b 1, 6′b 2 that are parallel in terms of flow. In the example shown, this runner channel portion comprises the two channel branches 6′b 1 and 6′b 2; in alternative configurations, it may also include more than two channel branches that are parallel in terms of flow and/or a plurality of channel branches lying one behind the other in the direction of flow.
In the exemplary embodiment of FIGS. 8 and 9, each of the two channel branches 6′ b 1, 6′b 2 forms a runner channel branch narrowing conically from the exit-side sprue opening 7′ toward the parting region 9′, and each channel branch 6′ b 1, 6′b 2 is surrounded by multiple heating elements of the active heating device 14, as can be seen in particular from FIG. 9. The active cooling device 13 includes circular cooling channels, which are arranged radially outside the two runner channel branches 6′ b 1, 6′b 2, surrounding them. The exit-side sprue opening 7′ correspondingly comprises the two outlet openings of the runner channel branches 6′ b 1, 6′b 2, and a to this extent modified opposite region 17′, which contains the active cooling channel structure 11, and is correspondingly provided on the die-cavity side with a gate region 8′1, 8′2 for each of the runner channel branches 6′ b 1, 6′b 2. In this way, melt is directed by way of the runner channel branches 6′ b 1, 6′b 2 and the gate regions 8′1, 8′2 at associated various locations into the die cavity 12.
FIGS. 10 and 11 illustrate an exemplary embodiment similar to that of FIGS. 8 and 9, with the difference that the two runner channel branches 6′ b 1, 6′b 2 into which the runner channel portion between the parting region 9′ and the exit-side sprue opening 7′ branches are implemented in some other way. Specifically, for this purpose the runner channel portion 6′b is formed frustoconically by analogy with the configurational variants of FIGS. 3 to 7. Into this runner channel portion 6′b conically narrowing in a frustoconical manner from the exit-side sprue opening 7′ to the parting region 9′ there protrudes a correspondingly frustoconical continuation 19 of a to this extent modified opposite region 17″ of the movable die half 3′, which is provided with two circumferentially opposite axial grooves, which in this case form the two channel branches 6′ b 1, 6′b 2 and go over into the gate regions 8′1, 8′2. In the example shown, a cooling channel 11 a extends as part of the active cooling device 11 into the region of the continuation 19, whereby the cooling effect for the runner channel branches 6′ b 1, 6′b 2 can be intensified.
As the exemplary embodiments shown and explained above make clear, the invention provides an advantageous sprue system which makes possible a defined detachment of the melt in the runner channel at a preferably relatively small distance from its exit-side sprue opening into the die cavity, or as shown into the upstream sprue/gate cavity, while at the same time an undesired escape of still liquid molten material from the fixed die half when the die is opened can be avoided, without a mechanical closure system being absolutely necessary for this. The sprue system according to the invention is suitable for all applications such as are known for conventional sprue systems, and in particular also as a hot runner sprue system for the diecasting of zinc, aluminum and magnesium in an increased temperature range of up to about 750° C.

Claims

1-11. (canceled)

12. A sprue system for a diecasting die, comprising:

at least one runner channel, which extends from an entry-side sprue mouth opening to an exit-side sprue opening, which opens into a die cavity of the diecasting die that is formed between a fixed die half and a movable die half or into a gate region arranged upstream thereof and comprises an at least one of geometrically and thermally defined parting region upstream of the sprue opening and downstream of the sprue mouth opening,

wherein the runner channel has a bend or kink in the parting region.

13. The sprue system as claimed in claim 12, wherein the runner channel has in the parting region a constriction, from where its through-flow cross section increases downstream and/or upstream.

14. The sprue system as claimed in claim 12, wherein the parting region is at a distance in front of the sprue opening of between 0.3 times and 3 times a diameter of the runner channel in the parting region.

15. The sprue system as claimed in claim 12, wherein a runner channel portion between the parting region and the exit-side sprue opening is assigned a cooling channel structure.

16. The sprue system as claimed in claim 12, wherein, in a region adjoining the parting region upstream, the runner channel runs at an angle of greater than 0° and less than or equal to 45° to the direction of a normal to a parting plane between the fixed die half and the movable die half, rising in the direction of the parting region.

17. The sprue system as claimed in claim 12, wherein it is configured as a hot runner sprue system and comprises a melt manifold block, which on the entry side has the sprue mouth opening, and a sprue block, which adjoins the melt manifold block in the direction of flow and on the exit side has the sprue opening, wherein the parting region is located in a portion of the runner channel that runs in the sprue block.

18. The sprue system as claimed in claim 12, wherein it is configured as a hot runner sprue system and the at least one runner channel comprises at least two runner channels that are parallel in terms of flow and temperature control means are provided, designed for controlling in an open-loop or closed-loop manner the temperature of the molten material in the parting regions of the runner channels independently of one another to a predeterminable setpoint temperature of between 0.9 times and 1.1 times a liquidus temperature of the molten material.

19. The sprue system as claimed in claim 18, wherein the temperature control means comprise an open-loop temperature control unit or a closed-loop temperature control unit and, for the respective runner channel, at least one of a temperature sensor system between the parting region and the exit-side sprue opening, the heating device between the parting region and the exit-side sprue opening, the heating device in the runner channel portion adjoining the parting region upstream, the cooling channel structure in the region of the movable die half opposite the sprue opening, and the cooling channel structure between the parting region and the exit-side sprue opening.

20. The sprue system as claimed in of claim 12, wherein the runner channel portion adjoining the parting region upstream and narrowing conically toward the parting region goes over at an associated transitional location into a cylindrical runner channel portion of a constant diameter adjoining upstream and its axial length is less than that of the runner channel portion between the parting region and the exit-side sprue opening.

21. The sprue system as claimed in claim 12, wherein the region of the movable die half that is opposite the sprue opening has a recess or is formed as level.

22. The sprue system as claimed in claim 12, wherein the runner channel portion extending from the parting region to the exit-side sprue opening branches into multiple channel branches that are parallel in terms of flow.

23. A sprue system for a diecasting die, comprising

wherein at least one of a runner channel portion between the parting region and the exit-side sprue opening and a runner channel portion adjoining the parting region upstream and narrowing conically toward the parting region is assigned a heating device.

24. The sprue system as claimed in claim 23, wherein the runner channel has in the parting region a constriction, from where its through-flow cross section increases downstream and/or upstream.

25. The sprue system as claimed in claim 23, wherein the parting region is at a distance in front of the sprue opening of between 0.3 times and 3 times a diameter of the runner channel in the parting region.

26. The sprue system as claimed in claim 23, wherein a runner channel portion between the parting region and the exit-side sprue opening is assigned a cooling channel structure.

27. The sprue system as claimed in claim 23, wherein, in a region adjoining the parting region upstream, the runner channel runs at an angle of greater than 0° and less than or equal to 45° to the direction of a normal to a parting plane between the fixed die half and the movable die half, rising in the direction of the parting region.

28. The sprue system as claimed in claim 23, wherein it is configured as a hot runner sprue system and comprises a melt manifold block, which on the entry side has the sprue mouth opening, and a sprue block, which adjoins the melt manifold block in the direction of flow and on the exit side has the sprue opening, wherein the parting region is located in a portion of the runner channel that runs in the sprue block.

29. The sprue system as claimed in claim 23, wherein it is configured as a hot runner sprue system and the at least one runner channel comprises at least two runner channels that are parallel in terms of flow and temperature control means are provided, designed for controlling in an open-loop or closed-loop manner the temperature of the molten material in the parting regions of the runner channels independently of one another to a predeterminable setpoint temperature of between 0.9 times and 1.1 times a liquidus temperature of the molten material.

30. The sprue system as claimed in claim 29, wherein the temperature control means comprise an open-loop temperature control unit or a closed-loop temperature control unit and, for the respective runner channel, at least one of a temperature sensor system between the parting region and the exit-side sprue opening, the heating device between the parting region and the exit-side sprue opening, the heating device in the runner channel portion adjoining the parting region upstream, the cooling channel structure in the region of the movable die half opposite the sprue opening, and the cooling channel structure between the parting region and the exit-side sprue opening.

31. The sprue system as claimed in of claim 23, wherein the runner channel portion adjoining the parting region upstream and narrowing conically toward the parting region goes over at an associated transitional location into a cylindrical runner channel portion of a constant diameter adjoining upstream and its axial length is less than that of the runner channel portion between the parting region and the exit-side sprue opening.

32. The sprue system as claimed in claim 23, wherein the region of the movable die half that is opposite the sprue opening has a recess or is formed as level.

33. The sprue system as claimed in claim 23, wherein the runner channel portion extending from the parting region to the exit-side sprue opening branches into multiple channel branches that are parallel in terms of flow.

34. A sprue system for a diecasting die, comprising

wherein a region of the movable die half opposite the sprue opening has a cooling channel structure.

35. The sprue system as claimed in claim 34, wherein the runner channel has in the parting region a constriction, from where its through-flow cross section increases downstream and/or upstream.

36. The sprue system as claimed in claim 34, wherein the parting region is at a distance in front of the sprue opening of between 0.3 times and 3 times a diameter of the runner channel in the parting region.

37. The sprue system as claimed in claim 34, wherein a runner channel portion between the parting region and the exit-side sprue opening is assigned a cooling channel structure.

38. The sprue system as claimed in claim 34, wherein, in a region adjoining the parting region upstream, the runner channel runs at an angle of greater than 0° and less than or equal to 45° to the direction of a normal to a parting plane between the fixed die half and the movable die half, rising in the direction of the parting region.

39. The sprue system as claimed in claim 34, wherein it is configured as a hot runner sprue system and comprises a melt manifold block, which on the entry side has the sprue mouth opening, and a sprue block, which adjoins the melt manifold block in the direction of flow and on the exit side has the sprue opening, wherein the parting region is located in a portion of the runner channel that runs in the sprue block.

40. The sprue system as claimed in claim 34, wherein it is configured as a hot runner sprue system and the at least one runner channel comprises at least two runner channels that are parallel in terms of flow and temperature control means are provided, designed for controlling in an open-loop or closed-loop manner the temperature of the molten material in the parting regions of the runner channels independently of one another to a predeterminable setpoint temperature of between 0.9 times and 1.1 times a liquidus temperature of the molten material.

41. The sprue system as claimed in claim 40, wherein the temperature control means comprise an open-loop temperature control unit or a closed-loop temperature control unit and, for the respective runner channel, at least one of a temperature sensor system between the parting region and the exit-side sprue opening, the heating device between the parting region and the exit-side sprue opening, the heating device in the runner channel portion adjoining the parting region upstream, the cooling channel structure in the region of the movable die half opposite the sprue opening, and the cooling channel structure between the parting region and the exit-side sprue opening.

42. The sprue system as claimed in of claim 34, wherein the runner channel portion adjoining the parting region upstream and narrowing conically toward the parting region goes over at an associated transitional location into a cylindrical runner channel portion of a constant diameter adjoining upstream and its axial length is less than that of the runner channel portion between the parting region and the exit-side sprue opening.

43. The sprue system as claimed in claim 34, wherein the region of the movable die half that is opposite the sprue opening has a recess or is formed as level.

44. The sprue system as claimed in claim 34, wherein the runner channel portion extending from the parting region to the exit-side sprue opening branches into multiple channel branches that are parallel in terms of flow.