WO2018177460A1 - Heating insert for a primary shaping tool and primary shaping tool - Google Patents

Abstract

The invention relates to a heating insert for a primary shaping tool having a cavity (2, 2.1) with a moulding surface (3), approximately one plastic injection moulding tool, characterised in that the heating insert (5, 5.1, 5.2, 5.3) comprises an inductor assembly (6) and an induction element (8) that can be heated by the inductor assembly (6), as well as a temperature-control element (10, 10.1, 10.2) connected to the induction element (8) in a heat-conducting manner and produced from a material with a higher heat conductivity in relation to the conductivity of the induction element (8), with at least one heat-coupling surface (13) with which the temperature-control element (10) can be connected in a heat-conducting manner to the tool or tool segment (1, 1.1) having the moulding surface (3).

Description

Heating insert for a prototype tool as well

original form tool

The invention relates to a heating insert for a cavity having an impression surface exhibiting

Original mold. The invention further relates to an arching tool for prototyping a heated

Substance or mixture of substances by cooling the same in a molding surface having a cavity of the forming tool with at least one distance from the molding surface of a tool or

Tool segment arranged heating insert. The

The invention further relates to a primary mold.

In injection molding of molded parts

thermoplastic, thermoset or elastomeric materials, the previously plasticized material is introduced into the cavity of a master mold. Such an archetype is composed to form the cavity of a plurality of tool segments, which can be separated from each other for demolding of the cooled in the cavity workpiece. The coming into contact with the plastic molding compound surfaces of the molds are in the context of this

Designs addressed as molding surfaces. The image of the impression surfaces defines the surface of the workpiece. The molding accuracy on the surface of the workpiece may be affected by defects, such as by Bindenahtkerben,

Shin differences or cloud and streaking. Such surface defects can by

uneven molding surface temperatures of

Forming tools are created. In order to ensure the molding accuracy for the plasticized mass introduced into the cavity of a mold,

for example, a plastic melt, too

improve, is known, the mold wall temperature - ie the temperature of the molding surfaces of the

Forming tools - to increase, causing the

Flowability of introduced into the cavity

Plastic melt is improved in its outer edge region.

For tempering such molds they have tempering channels, through which for holding the mold at a certain temperature or for heating the same to a certain temperature appropriately tempered fluids, for example

Water or oil is passed. If such molds in certain areas should have a different temperature from the basic, higher temperature, in addition electrical

Heating inserts or in the case of a local

Lowering temperature arranged electrical cooling elements in recesses of the mold. Also, molds are known in which the

Cooling elements for a defined cooling of the

Plastic melt and thus the

Cooling process, thus shorten the cycle time.

From DE 199 29 731 AI a mold is known, which is inductively heated to introduce additional heat into the cavity as a whole and for this purpose of an electrically conductive

Material exists. In US 4,439,492 is a

Forming tool described in which for heating the Induction-based heating inserts are placed in the cavity. After heating the

Impression surfaces of the molds becomes the mold

opened, the heating element removed, before the mold then to carry out the actual

Injection molding process is closed again. The concept of this mold is based on the idea that by inserting the inductive

operated heating insert not the whole

Forming tool, but only the molding surfaces and the immediately adjacent thereto

 Mold tool areas are heated. This should also shorten the cycle times. A

Control of the temperature during the

Injection molding process is not possible with this concept.

With the known means molding tools can be heated. The cycle times at

 Plastic injection molding will be instrumental in hardening the plasticized state into the mold

Cavity of the mold introduced material determined. In order to shorten the cycle times, molding tools have been developed which, in addition to the temperature control channels provided for heating the molding tool, additionally have tempering passages through which a coolant can flow. Such a mold can thus be heated and cooled. Is disadvantageous in such a way

designed mold that relatively sluggish

Temperature behavior considered. To counter this disadvantage, DE 102 57 129 AI proposes to heat induction surfaces of a mold inductively, by the heating of a the first molding surface used inductor is integrated in a first mold, which is opposite to the molding surface of a second mold to be heated. Thus, the inductor is separated in this prior art mold by the cavity of the molding surface to be heated. To the

To allow heating of a molding surface in this way, it is necessary that the molding surface to be heated of the molding tool consists of a material suitable for this purpose. This material

differs in most cases from the material of the other, serving to form the cavity molds. To surface defects at the transition of the material required for heating and the impression surface material more

Cavity limitations do not appear to make these transitions must be worked very carefully or the entire the cavity

enclosing surface is made of this material. In addition, that can be done in this

Document described method can only be used for certain tool geometries.

From DE 20 2009 901 959 Ul a mold is known in which the inductor is a copper waveguide. This coolant is flowed through. Heating takes place via use of the inductor for

Heating the tool segment in which the

Inductor is located. The copper waveguides are

Coolant flows through, so that in this way the inductor itself can be cooled. That the

However, copper fluid flowing through cooling fluid is also used for accelerated cooling of the

Tool segment used in which the Copper waveguides are added as inductors. These are typically in one

smaller distance to the molding surface of the tool than the usual Temperiermittelkanäle.

For the purpose of local heating of a

Impression surface area will too

Resistance heating elements used. Due to their dynamics, they stay on permanently. To a thermal separation between the

Resistance heating element and the tool wall to prevent overheating and to support a cooling process, these along a linear lifting movement of the tool wall after

Reaching the required mold wall temperature reduced by a certain distance. To the

again to provide desired mold wall temperature in the next cycle, these are then moved back up to the mold wall. A disadvantage of this is the necessary actuators to move such a resistance heating to effect the thermal separation. In addition, this requires a corresponding space. Therefore, the use of such a concept is limited.

In this prior art forming tool or the inductors are integrated into the tool or one or more of its tool segments.

Moreover, it would be desirable if cycle times could be further reduced.

The invention is thus based on the object, a heating insert for a master mold and a equipped with at least one heating insert Propose original tool, in which a

in particular local or regional temperature control of the impression surface while shortening the cycle times is possible.

This object is achieved according to the invention by a heating insert of the type mentioned, in which the heating insert an inductor and a heatable by the Induktorbaugruppe induction body and connected to the induction body in heat-conducting connection tempering,

made of a material with a higher conductivity compared to the induction body

Thermal conductivity, with at least one

Heat coupling surface, with the tempering in thermally conductive connection to the mold surface having tool or tool segment

is connectable, has.

This object is also achieved by a generic tool mentioned above, which has at least one such heating insert.

The special feature of this heating insert is that this is a heating insert in hybrid construction. This heating insert includes one

Induction body by one or more

Induktorbaugruppen can be heated. In

thermally conductive connection to the induction body, a tempering is connected, which supplies the heat generated in the induction body to the tool or tool segment. The tempering is made of a material with a relation to the

Thermal conductivity of the induction body clearly higher thermal conductivity produced. In this respect, in this heating insert a functional separation between the induction body and the for the

Feeding and heat to the tool or

Tool segment with the serving to be heated molding surface serving tempering. Of the

Induction body is necessarily made of a material with ferromagnetic properties

manufactured, typically a steel material. The tempering body, however, needs no

have ferromagnetic properties. Thus, this can be made of a, heat particularly well conductive material, such as copper or a

Copper alloy, also be made of brass. The effect brought about by such a heating insert is that the heat transfer from the induction body to the molding surface area to be heated takes place more rapidly due to the interposition of the tempering body which conducts the receiving heat flow in a particularly good manner, compared to an embodiment in which the induction body is also used for the

Heat transfer to the desired location of the

Tool or tool segment is responsible. Due to the use of a tempering and its heat well conductive material property, the coupled from the induction body in this heat can also be placed in tool areas in or on which an inductor, for example, lack of sufficient space can not be arranged and therefore these areas can not be additionally heated. Such heat well conductive

Material, such as a copper material is compared with the materials from which

Tool segments made for a master mold become significantly softer, typically tool steel. This property can be found in the connection of the tempering with his

Heat coupling surface to the tool or

Take advantage of tool segment, if the

 Temperierkörper to the complementary surface of the

Tool or tool segment is pressed. Surface irregularities on the tool or

Tool segment then interfere with the formation of a particularly large-area thermal contact surface.

Surface irregularities are expressed in the relatively softer surface of the heat coupling surface of the

Tempering a. The same applies to the connection of the induction body to the tempering.

In this respect, to provide a

thermally conductive connection between the

Induction body and the tempering and from the tempering in the tool, the softer material properties of the tempering

clever way to be used. The connection of the

Temperierkörpers to the induction body - on the one hand - and to the tool or tool segment - on the other hand - can also by others

 Connection technologies occur, for example, by a joining process, such as by

 Electron beam welding, laser welding, soldering or a generative process.

The improved by the tempering improved thermal conductivity of the induction body to the tool in and during the cooling process of the tool on the tempering in the induction body and of this in the typically coolant

flowed through copper waveguide inductor assembly are for a prototype with shorter cycle times

responsible. The cycle times can be reduced even further if the tempering element itself is cooled. This is provided in one embodiment. The tempering body has

Coolant channels, for example, as

Capillary channels can be formed. These are connected to a coolant circuit of the primary mold associated coolant system. In this way, the cooling process after introduction of the heated mass to be molded into the cavity of

Urformwerkzeuges in the Abformoberflächenbereich on which the heating element acts are cooled particularly quickly. The effectiveness of such cooling can be further improved if, within the tempering in a section with a small portion to the heat coupling surface

is arranged, a cavity is provided, open into the at least two coolant channels. Of these, one sets up one feed and the other one

Return of a coolant circuit is a particularly effective cooling with only a small diameter of the coolant channels, for example, if designed as Kapillarkanäle is possible with gaseous nitrogen. In addition to the above

described embodiments in which the coolant channels of the tempering to a

Coolant circuit are connected, can also be used to cool the tempering

lost coolant to be worked. Then at least one coolant channel of the

Temperierkörpers to a coolant supply

connected. The return is discharged into the environment. Even if nitrogen as an example Coolant is addressed, which is particularly suitable for the cooling of the tempering, when incorporated in these capillary channels, other coolants can be used.

With such a heating insert can of it

influenced impression surface area in a short time on one compared to the other areas of the

Impression surface can be brought higher temperature. Due to the above-described possibilities of a particularly effective cooling of the brought to a higher temperature Abformoberflächenbereich can be cooled just as quickly or even with cooled tempering even faster than this has been heated, so that the cycle times not by the

otherwise necessary prolonged waiting for cooling of the additional heated surface areas until the cavity can be opened to eject the molded product is delayed.

Thus, such a heating insert is suitable for

Archetypes, such as

 Injection molding tools, used in the manufacturing plastics industry, when a variotherm

Temperature control is provided.

Quite possible is also the use of such a heating insert, in which the heat coupling surface of its tempering directly forms a molding surface or Abformflächenteil a cavity. This is useful for small urzuformenden plastic parts, since then an additional heat transfer can be avoided. Especially with small ones

urzuformenden plastic parts is partly with worked considerable internal pressures, so that by this measure, movements of a

 Tool segment are avoided compared to the heating element. Sometimes have such urformed

Plastic parts very small dimensions contours. This is the case, for example, with optical bodies such as lenses, for example Fresnel lenses. With such an embodiment of the heating insert, its tempering body with its heat coupling surface forms a tool segment which, together with at least one second tool segment, surrounds the cavity. The tool segments are adjustable against each other for opening and closing the cavity. The one or more other tool segments may be unheated. In such a use of the heating insert, the surface of the tempering itself the

Represent molding surface. It is also entirely possible for the heat coupling surface of the tempering body to be provided with a wear-resistant hard layer

is coated. Then the outside of this coating represents the heat coupling surface. Forms the heat coupling surface of the heating insert itself

Impression surface, the heat is transferred directly from the heating insert in the introduced into the cavity

Plastic compound coupled.

The invention is described below with reference to a

Embodiment described with reference to the accompanying figures. Show it:

Fig. 1: a schematic sectional view of a tool segment as part of a forming tool with a heater insert and a therein

heating insert to be used, the heating element connected to the tool segment, a heating insert of an alternative embodiment of the inductor connected to a tool segment corresponding to the representation of FIG. 2, a heating insert according to a further embodiment and application and a heating insert corresponding to that of FIG. 4 in a further embodiment.

Incidentally, not shown in detail

Urformwerkzeug has several, but at least two tool segments. Such a tool segment 1 is shown in Figure 1 in a section. The tool segment 1 is made of a tool steel. His pointing in the cavity 2

Impression surface is denoted by the reference numeral 3

indicated. In the opposite side of the impression surface 3 of the tool segment 1 - in the figure, this is the underside of the

Tool segment 1 - is a Heizelementaufnahme 4 introduced. The Heizelementaufnahme 4 of

illustrated embodiment has a circular cross-sectional geometry.

A total by the reference numeral 5

characterized heater is used to heat the heater insert 4 opposite Area of the impression surface. This and the adjacent areas should, if in the cavity di warm plastic mass is used, to a higher temperature than the other areas of the

Be brought impression surface. Also, the

Heating insert 5 can be used to keep the molding surface at the temperature of the plastic mass longer or to reheat. The heating element 5 of the illustrated

 Embodiment comprises an inductor

6. This has as an inductor via an inductor coil

7, made of a waveguide, which is shaped like a coil. Even if for the purpose of cooling a waveguide in the illustrated

 Embodiment is used, at this point also a full conductor (wire) can be used. This copper waveguide is in a manner not shown to a

Coolant circuit is connected and coolant flows through it, if with the inductor assembly 6 heat is to be generated. Not shown

likewise the energization of the copper waveguides of the inductor coil 7. The inductor assembly 6 is connected to an induction body 8 in a thermally conductive connection. This is designed as a sleeve and contributes to the lateral protection of the inductor 6 on the underside a radially outwardly projecting flange 9. The induction body 8 is in the illustrated embodiment of a

Made of steel material. Its thermal conductivity can be given as about 45 to 50 W / (mK). In an operation of the induction assembly 6 of the Heats induction body 8 due to its ferromagnetic properties.

The induction body 8 is in turn connected in thermally conductive connection to a tempering 10.

This is made of a copper material and has a thermal conductivity of about 280 to 300 W / (m-K). The induction body 8 summarizes the

Temperature control body 10 in a section 11 a. In this section 11 of the tempering 10 is pressed into the sleeve-like induction body 8. This ensures a particularly good heat-conducting transition from the induction body 8 in the

Temperierkörper 10. The tempering 10 of the illustrated embodiment carries a

 Temperierkörperkopf 12, which opposite the enclosed by the induction body 8 section 11 has a larger diameter and the flange 9 opposite the opposite end of the induction body 9 and the Induktorbaugruppe 6 surmounted. The im

 Diameter larger temperature control head 12 is used to distribute in the section 11 via his

cylindrical, adjacent to the induction body 8 coupling surface received heat over a larger area. The tempering body head 12 has a

 Heat coupling surface 13 on. The heat coupling surface 13 is that surface which in

Contact with the inner surface of the

Heating insert 4 of the tool segment 1

arrives. The geometry of the Temperierkörperkopfes 12 is complementary to the cross-sectional geometry of

Heizelementaufnahme 4 executed and therefore also in the illustrated embodiment

circular. It is understood that the Tempering head also any other,

In particular, non-rotationally symmetrical shapes as well as extensions may have, if the molding surface area of the tool to be heated such a differentiated embodiment of the

heated surface demands.

The tempering body 10 has a cavity 14 in the region of its tempering body head 12.

Due to the heat well conductive properties of the

Temperierkörpers 10 affects this one

Heat flow from its section 11 to

 Heat coupling surface 13 is not. The spherically designed in the illustrated embodiment cavity 14 is executed on as capillary channels

 Coolant channels 15, 16 connected. The

Coolant channels 15, 16 are in a manner not shown to a nitrogen-operated

Coolant system connected. It serves the

Coolant channel 15 as an inlet and the coolant channel

16 as return to and from the cavity 14. In the figures, the flow direction in the

Coolant channels 15, 16 with directional arrows

indicated. Are the coolant channels 15, 16 and thus the cavity 14 flows through coolant, this results in a particularly effective and thus rapid removal of heat from the impression surface. In a not shown in the figures

Embodiment are in the tempering

Coolant channels also introduced previously written purpose, but without these open into a designed in the manner of a collector cavity. FIG. 2 shows the heating insert 5 inserted into the heating insert receptacle 4 of the tool segment 1. The heating insert 5 can, for example with the aid of a tensioning clip (not shown) in this

Be held in position. The connection of the

 Heating element 5 on the back of the tool segment 1 takes place on its heat coupling surface 13 in a heat well conductive connection, so that a heat transfer from the tempering 10 in the tool segment 1 and vice versa is influenced as little as possible.

Preferably, the heat coupling surface 13 with a certain bias to the back of the

Tool segment 1 connected. This connection is permanent.

During operation of the forming tool, the heating insert 5 of the region of the molding surface 3 situated in the vicinity of the heat coupling surface 13 can be heated to a specific temperature prior to introducing the material to be molded. If this is to be formed mass introduced into the cavity 2, if desired, a reheating can take place. Regardless of this, then the heating element 5 as a heat sink

used by heat from the molding surface 13 via the tempering 10 by means of the

 Copper waveguide flowing through coolant (at this time, these conductors are energized) and are removed particularly quickly by the additional cooling of the temperature control body 10 via the coolant channels 15, 16 and the cavity 14.

In the illustrated in the figures

Embodiment, the inductor is designed as a copper tube. Quite possible is also a Embodiment of the inductor, in which this one

Stainless steel tube with an externally applied Cu coating. This can be applied for example by a PVD method. An advantage of such a configuration is that with such

Tubes can realize much smaller diameter.

Also possible is an embodiment of a pipe designed as an inductor, if this over the circumference at its in the direction of the induction body

directed side has gas-permeable small holes. There is a possibility that

Induction tube with nitrogen to flush, in this way a particularly effective and thus rapid

To achieve cooling of the induction body. In an embodiment in which the induction body

Having tempering channels, as this is described to the embodiment shown in the figures, then the induction body would be cooled from the inside and outside.

FIG. 3 shows a further heating insert 5.1,

connected to a tool segment 1.1. Of the

Heating insert 5.1 is designed as the

above-described heating element 5. Therefore, the same parts are also identified by the same reference numerals. The heating insert 5.1 differs from the

Heating insert 5 only in that the

Inductor 6 magnetic field concentrators 17 are assigned. These concentrate the magnetic field provided by the induction and thereby improve the efficiency. This affects not only in terms of the introduced energy, but also on the heating rate. With regard to the power required to increase the temperature, by using one or more magnetic field concentrators, which in the illustrated embodiment, annular in the

 Inductor assembly 6 are integrated to be reduced by 50% to 70%. Particularly high warm-up and

Cooling rates can be with a

Heating insert, as the heating insert 5.1 realize the inductor coil purged nitrogen and in

Direction to the induction body directed small outlet openings.

Figure 4 shows a further heating element 5.2, which is basically constructed as the heating element 5.1 of

Figure 3. Therefore, the same components are identified by the same reference numerals.

The heating element 5.2 is part of a forming tool 18, in which the heat coupling surface 13.1 of

 Temperierkörpers 10.1 at the same time forms a molding surface of the cavity 2.1. With the as a molding surface

serving heat coupling surface 13.1 of the heating element 5.2 acts to form the cavity 2.1, a second tool part 19 together. The tool part 19 is for

Opening and closing the cavity 2.1 relative to the heating insert 5.2 adjustable as a tool part. The primary mold 18 is designed to urinate in the cavity 2.1 plastic lenses. For this purpose, the heat coupling surface 13.1 of the tempering 10.1 is concavely curved to a convex on this side

To be able to mold the lens surface. As

Forming surface serving heat coupling surface 13.1 may be microstructured. The same applies to the Cavity 2.1 limiting surface of the tool part 19.

Yet another heating element 5.3 is shown in FIG. The heating element 5.3 corresponds in turn to the heating element 5.2 of Figure 4. The heating element 5.3 differs from the heating element 5.2 solely by the formation of its impression surface - the heat coupling surface 13.2 -. This is applied to the heating element 5.3 as the relevant surface of the tempering 10.2

wear-resistant hard layer 20 executed. FIG. 5 shows the primary mold 21 with the cavity open.

The invention has been explained with reference to embodiments. The remarks to the

Embodiment clarify that in particular with the use of capillary cooling of the

Temperierkörpers 10, such a heating element 5 can be built very small and compact. Without departing from the scope of the applicable claims, numerous others will be apparent to one skilled in the art

Possibilities to implement the invention without this in the context of this embodiment in

Individual would have to be explained.

LIST OF REFERENCE NUMBERS

1, 1.1 Tool segment

 2, 2.1 cavity

 3 impression surface

4 heating insert

■ 5 ^ 5 · 1 ^ 5 · 2 ^ _· 5 · 3 heating insert

 6 inductor assembly 7 inductor

8 induction bodies

9 flange

 10, 10.1, 10.2 tempering bodies

 11 section

12 tempering head

13, 13.1, 13.2 heat coupling surface

14 cavity

15 coolant channel

16 coolant channel

17 Magnetic field concentrator 18 Original mold

19 Tool part

20 hard coating

21 Original mold

Claims

claims 1. heating insert for a cavity (2, 2.1) with  an impression surface (3) exhibiting  Urformwerkzeug, about one  Plastic injection mold, by  in that the heating insert (5, 5.1, 5.2, 5.3) has an inductor assembly (6) and a heater that can be heated by the inductor assembly (6)  Induction body (8) and one to the  Induction body (8) in a thermally conductive connection temperature control body (10, 10.1, 10.2), made of a material having a relation to the conductivity of the induction body (8) higher thermal conductivity, with at least one  Heat coupling surface (13), with the  Temperature control body (10) in heat-conducting connection to the mold surface (3) having tool or tool segment (1, 1.1) can be connected has. 2. Heating insert according to claim 1, characterized  characterized in that the induction body (8) is made of a ferrous material, in particular steel. 3. Heating element according to claim 1 or 2, characterized  in that the tempering body (10) is made of copper or a copper alloy. 4. Heating element according to one of claims 1 to 3,  characterized in that in the Temperierkörper (10) coolant channels (15, 16) with Connections to a coolant circuit  are provided. 5. Heating insert according to claim 4, characterized  characterized in that the coolant channels (15, 16) of the tempering (10) are designed as Kapillarkanäle. 6. Heating insert according to claim 4 or 5, characterized  characterized in that within the  Temperierkörpers (10) below his  Heat coupling surface (13) a cavity (14)  is provided, in which at least one  Coolant channel (15) open as a feed and at least one other coolant channel (16) as a return , Heating element according to one of claims 1 to 6,  characterized in that the Induktorbaugruppe (6) coolant flowed through copper waveguide. , Heating element according to one of claims 1 to 7,  characterized in that the induction body (8) as a sleeve and the Induktormaugruppe (6) are designed as surrounding the sleeve bobbin (7). Heating element according to one of claims 1 to 7, characterized in that the tempering (10) has a portion (11) to which the  Induction body (8) borders, and a relative to the portion (11) projecting head-like Section (12) having a relation to the base of the portion (11) larger Base, which head-shaped portion (12) carries the heat coupling surface (13). 10. Heating insert according to one of claims 1 to 9, characterized in that the heat coupling surface (13) of the tempering body (10) in heat-conducting connection to that of a molding surface (3)  exhibiting tool or tool segment (1, 1.1) can be connected. 11. Urformwerkzeug for prototyping a heated substance or mixture by cooling  in a cavity (2, 2.1) of the same having an impression surface (3)  Urformwerkzeuges, characterized in that the Heating element (5, 5.1) is designed according to one or more of claims 1 to 10 and this with its heat coupling surface (13, 13.1, 13.2)  is connected below the impression surface (3) of a tool or tool segment (1) or the heat coupling surface (13.1, 13.2) is part of the impression surface of the cavity (2, 2.1) of the  Forming tool (18, 21) forms. 12. forming tool according to claim 11, characterized  characterized in that the heating element (5, 5.1) is designed according to one of claims 4 to 7 and the forming tool (18, 29) is associated with a cooling system with at least one coolant circuit to which the at least one heating element (5) with its coolant channels (15 , 16) connected. 13. forming tool according to claim 12, characterized in that the primary mold (18, 21) are assigned two working with different coolant coolant circuits, wherein in a refrigerant circuit nitrogen in gaseous form is promoted as a coolant and this  Coolant circuit to the coolant channels (15, 16) of the tempering (10) of the at least one heating element (5) is connected. 14. forming tool according to one of claims 11 to 13, characterized in that at a  Embodiment in which the heat coupling surface  (13.2) of the tempering of an impression surface, the heat coupling surface (13.2) by a on the tempering on his  Heat coupling surface (13.2) applied  Heat coupling layer is formed. 15. Forming tool according to claim 13, characterized  in that the heat-coupling layer (13.2) is a wear-resistant hard layer.