CA2053922A1 - Process and device for controlling and regulating the mould filling rate and casting pressure of a low pressure chill casting machine - Google Patents
Process and device for controlling and regulating the mould filling rate and casting pressure of a low pressure chill casting machineInfo
- Publication number
- CA2053922A1 CA2053922A1 CA002053922A CA2053922A CA2053922A1 CA 2053922 A1 CA2053922 A1 CA 2053922A1 CA 002053922 A CA002053922 A CA 002053922A CA 2053922 A CA2053922 A CA 2053922A CA 2053922 A1 CA2053922 A1 CA 2053922A1
- Authority
- CA
- Canada
- Prior art keywords
- pressure
- probe
- chamber
- casting
- furnace chamber
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- 238000005266 casting Methods 0.000 title claims abstract description 76
- 230000001276 controlling effect Effects 0.000 title claims abstract description 15
- 238000000034 method Methods 0.000 title claims abstract description 8
- 230000001105 regulatory effect Effects 0.000 title claims abstract description 8
- 239000000523 sample Substances 0.000 claims abstract description 78
- 239000000463 material Substances 0.000 claims abstract description 37
- 239000007788 liquid Substances 0.000 claims abstract description 8
- 238000009423 ventilation Methods 0.000 claims description 10
- 230000000630 rising effect Effects 0.000 claims description 9
- 238000007599 discharging Methods 0.000 claims description 2
- 238000005058 metal casting Methods 0.000 claims 1
- 239000004411 aluminium Substances 0.000 abstract description 3
- 229910052782 aluminium Inorganic materials 0.000 abstract description 3
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 abstract description 2
- 229910052751 metal Inorganic materials 0.000 description 11
- 239000002184 metal Substances 0.000 description 11
- 230000008878 coupling Effects 0.000 description 3
- 238000010168 coupling process Methods 0.000 description 3
- 238000005859 coupling reaction Methods 0.000 description 3
- 238000003723 Smelting Methods 0.000 description 2
- 238000004140 cleaning Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 229910001338 liquidmetal Inorganic materials 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 230000007257 malfunction Effects 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 239000000155 melt Substances 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 230000011664 signaling Effects 0.000 description 1
- 230000002123 temporal effect Effects 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D18/00—Pressure casting; Vacuum casting
- B22D18/08—Controlling, supervising, e.g. for safety reasons
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Casting Support Devices, Ladles, And Melt Control Thereby (AREA)
- Encapsulation Of And Coatings For Semiconductor Or Solid State Devices (AREA)
- Injection Moulding Of Plastics Or The Like (AREA)
- Control Of Fluid Pressure (AREA)
- Casting Or Compression Moulding Of Plastics Or The Like (AREA)
- Blow-Moulding Or Thermoforming Of Plastics Or The Like (AREA)
- Molds, Cores, And Manufacturing Methods Thereof (AREA)
- Casting Devices For Molds (AREA)
Abstract
ABSTRACT
device and method for controlling and regulating the mold filling speed and the casting pressure of a low pressure chill casting machine, preferably for aluminium casting, whose hermetically closable furnace chamber receiving the liquid casting material can be connected to the chill mold via a riser tube leading to this, via which the casting material is pressed into the chill mold by means of gas pressure established in the furnace via a pressure gas feed line. A contact probe (13) is arranged at an adjustable height in a probe chamber (10) extending from above into the furnace chamber (7) and open at its lower end (8) for the entry of the casting material, which probe on the occurrence of contact supplies a signal to an arrangement (37) for control of the gas pressure feed flow to the furnace chamber (7). This contact probe is movable on the onset of contact in the probe chamber (10) to such a height that during the casting process is not reached by the level of the liquid casting material. Furthermore, a measuring arrangement (36) is provided for measuring the gas pressure in the furnace chamber (7), which supplies the measured pressure in the form of a signal to the arrangement (37) for controlling the pressure gas feed flow.
(Figure 1.)
device and method for controlling and regulating the mold filling speed and the casting pressure of a low pressure chill casting machine, preferably for aluminium casting, whose hermetically closable furnace chamber receiving the liquid casting material can be connected to the chill mold via a riser tube leading to this, via which the casting material is pressed into the chill mold by means of gas pressure established in the furnace via a pressure gas feed line. A contact probe (13) is arranged at an adjustable height in a probe chamber (10) extending from above into the furnace chamber (7) and open at its lower end (8) for the entry of the casting material, which probe on the occurrence of contact supplies a signal to an arrangement (37) for control of the gas pressure feed flow to the furnace chamber (7). This contact probe is movable on the onset of contact in the probe chamber (10) to such a height that during the casting process is not reached by the level of the liquid casting material. Furthermore, a measuring arrangement (36) is provided for measuring the gas pressure in the furnace chamber (7), which supplies the measured pressure in the form of a signal to the arrangement (37) for controlling the pressure gas feed flow.
(Figure 1.)
Description
2 ~ 2 2 PROCESS AND DEVICE FOR CONTROLLING AND REGULATING
THE MOULD FILLING RATE AND CASTING PRESSURE OF A
LOW-PRESSURE CHILL CASTING MACHINE
The invention relates to 2 device and a method for controlling and regulating the mold filling speed and the casting pressure of a low pressure chill casting machine, preferably fo- aluminium casting, whose hermetically closable furnace chamber or container for receiving the liquid casting material can be connected to the chill mould via a riser pipe leading thereto, via which the casting material is forced into the chill mold by means of gas pressure established in the furnzce chamber OI container via a gas supply line, at leas L one contact probe being arranged at an adjustable height in a probe chamber extending into the furnace chamber or container ~rom above and being open at its lower end for the entry of the casting material, which probe supplies a signal to a device for controlling the gas supply flow to the furnace chamber on contact with the casting material rising in the probe chamber as a result of the gas pressure.
Such a control device using at least one contact probe is already known (DE-AS 28 08 588). In this known device, a contact probe, likewise adjustable as to heigh , is used to control and regulate the gas pressure in the furnace chamber ove- the entire _ 2 - 2~a39~
casting cycle. The c~ntact probe has there two sensing needles having sensing points located at differing heights. The pressure qas inflow to the ,urnace chamber or container of the casting material is regulated in such marner that the li~uid level of S the casting materi21 in the probe ch2mber integrated in the riser tube is maintained between the lower and the upper sensing poin,s of the contact probe, the probe bein~ adjusted in height according to the desired gas pressure in the furnace chamber or container.
This known device has the disadvantage that during each casting process the sensing points- of the contact probe make multi~le or even continual contact with the liquid casting material or dip into this, whereby the contact probe rapidly loses its functional precision as a result of adhesion of residues and oxides of the casting material or as a result of attack by the casting material. ~oreover, for the probe chamber as a result of the cyclically rising and falling melt therein the danger exis~s of accretion by melt crystallizing out from the casting material, so that this chamber is heated just as strongly as the riser tube and must be maintained functional by regular cleaning.
Devices are also known for regulating the casting pressure in low pressure chill casting machines (DE-AS 23 31 956) in which the gas pressure in the furnace chamber or in the container for the liquid casting material is adjusted and regulated under computer control according to a predetermined pressure/time curve. The pressure gas is fed in through two gas inlets with differing flow ~ 3 ~ 2~33~22 cross-section. In ~_his connection, several contact probes are provided which are immovably arranged along the path of the riser tube of the casting ma~erial znd by msans of complicated pneumatic regulation me~be s effec. partial or complete opening or closure of the two gas inlets and thus ensure a regulatable gas pressure over wide limits according to the pre-set control. These contact probes are reinserted in each casting cycle into the liquid high pressure casting material extending up to or beyond the~, so that they are 2ssociated with the same disadvantage 25 the probe in the first mentioned known device.
The invention is therefore based on the object, with a device and method of the type initially mentioned, of maintaining unch2nged the functionality of the contact probe over a large number of casting cycles and thus excluding malfunctions in th~ control of the casting pressure, and arranging the control of the pressure gas feed introduced through the probe in a manner which is constructively as simple and operationally reliable as possible. This is achieved according to the invention in that upon contact with the casting material rising in the probe chamber as a result of the gas pressure, upon which it gives a signal to a device for controlling the gas pressure flow to the furnace chamber or container, the contact probe is movable in the probe chamber receiving it to a position of height such that it is not reached during the casting process by the level of the casting material, and in that a measuring arrangement is provided for measuring the gas pressure prevailing in the upper region of the furnace chamber or container for the casting material which provides the measured gas pressure in the form of a signal to the arrangement for controlling the gas pressure flow.
~ 4 ~ 2~922 The contact prcbe thus comes into operation only once during a c2sting cycle signalling the onset of contact .o the arra~gement for control of the gzs pressure flow, w~ereby the sequence of further control znd resulation of .he ~as pressure in the furnace ch2mber or container can be initiated as a function of time according to a predetermined programme. In this connection, the gas pressure measured at this ins.ant by the measuring arrangement in the furnace chcmber or container can be used as a reference pressure for the further control sequence.
~or further control of the gas pressure in the - furnace chamber, the gas pressure given in the furnace chamber or container with the provided measuring arran~ement can be continually re-measured and accordins to the respectively measured actual pressure and the desired pressure- pre-set by the control device the gas pressure flow to the furnace chamber or container can be controlled.
The short contact only once during an entire casting cycle between the contact probe and the high pressure casting material in the probe ch~mber given in the device according to the invention and this method ensures that the contact probe is largely protected and is maintained free of encrustation with casting material.~
The contact probe can be adjustable to such a height in the probe chamber that its sensing points lie approximately on the level of the outlet opening of the riser tube which can be connected to the chill mould. This height corresponds approximately to the level of casting material shortly before the beginning of mold filling, thus to a level which is located slightly beneath the mould cavity.
- - s - 2~ 22 Expediently, the probe chæmber, with the exception of its lower opening for the entry of the casting material, is hermetically closable so that above the casting materizl rising in this chamber a gas pressure can be generated which reliably prevents rising of the casting ma.erial to the contact probe at its raised position. ~o- this purpose, the probe chamber can be in connection in its upper region with the furnace chzmber or container for the liquid casting material Vi2 a pressure gas equalization line prodivided with a closure valve. This closure member can be 2 changeover valve which is controllable in such-manner that at the beginning of a casting cycle it is first open to the .upper probe chamber for external air (ventilating position) and closes the ventilation opening upon the onset of contact of ~he contact probe with the high pressure casting material in the probe chæmber and opens the pressure equalization line to the furnace chamber and thus per~orms gas pressure e~ualization between the probe chamber and the furnace ch~ber.
~or control of the gas pressure in the furnace chamber, the aperture cross-section of the pressure gas line is expediently adjustable in depenàence on the gas pressure preset in the furnace chamber or container by the control programme. In order to ensure setting of the aperture cross-section and thus the amount of gas pressure fed into the furnace chamber with the simplest possible control member, in a preferred embodiment the gas pressure feed line is divided into several branch lines which are brought together again before discharging into the furnace chamber or container and each having an unchangeable aperture cross-section, preferably in the form of a calibrated aperture, for the gas pressure as well as - 6 - ~ 22 a closure val~e. ~he calibrated apertures can have differing aperture openinss and be individually opened or closed in arbitr2ry combination by the arrangement for controlling the gas pressure inflow, whereby the respectively recuired pressure gas inflow to the furnace or container which is responsible for the increasing speed of the czsting material in the riser tube can be precisely controlled. This simple closins and opening control is cheap, technically unproblematical and ~ery unlikely to fail.
In Fig. 1 of the drawings is represented a particularly advantageous exemplary embodiment of the control device accoràing to the invention in a low pressure casting apparatus for aluminium casting lS which wlll be described in more detail in the following.
Fig. 2 shows the possible gas pressure control with the device according to the invention in the course of a casting cycle in a pressure time diagram.
The casting apparatus illustrated in ~ig. 1 consists of a metal smelting furnace 1 into which a riser tube 2 obliquely extends to the vicinity of its base, which tube is provided on its outer end with a connection flange 3 for coupling to a connection flange 4 having an inlet opening of a chill mold 5 with molding ca~ity 6. Into the furnace chamber 7, a tubular body 9 open at its lower end 8 likewise extends from above to the region of the base, which body 9 delimits a probe chamber 10 in which an electrical contact probe is arranged to be adjustable in height by means of a drive cylinder 12 controlled pneumatically or hydraulically via a valve 11. This contact probe consists of a contact plate 13 which is supported on a guide rod 14 activated by the drive ~ ~ 7 ~ 2~ 22 cylinder 12. The level of the casting material, the metal melt, located in the metal smelting furnace 1 is indiczted wi h 15, ~-hich ma~erial can be filled into the f~rn2ce chæmber 7 through a closable inlet 16. 3y means of the dri~re cylinder 12, the probe 13 c~n be adjusted and changed in height in the probe chamber 10 ~-ith ~he guiàe rod 14.
The probe chz~e- 10 -eceiving the probe 13 is hexmetically sealed with the exception of its lower entry opening 8 or the casting material, the inlet of a gas pressure equalization line 17 leading to the furnace chamber 7 and a ventilation opening in .he changeover valve 18. ~n the vicinity of the pressure equalization line 17, a pressure gas line 19 discharges into the furnace chamber. This pressure gas line is sub-divided into six branch lines 20 to which are combined together before discharge into the furnace chamber 7 and each of which has an open-shut control valve 26. The branch lines 20 to 24 are furthermore provideà with calibrated apertures 27 to 31 determining ~he flow of the gas volume, whicn have differing aperture cross-sections. The lines 20 to 25 proviàed with the calibrated apertures can be opened by their control ~alves 26 individually or in arbitrary combination, so that thereby the respectively necessary ~olume of pressure gas for the necessary speed increase in the riser tube 2 can be introduced through the gas feed line 19 into the furnace chamber 7~ The control valve 26 in the branch line 25 serves in conjunction with the choke valve 32 also arranged in this branch line moreover for regulation of the leakage equalization.
- 8 - 2~39~2 In order that the pressure gas feed line 19 can also be used for ~n,ila.ing the furnace chamber 7, a ventilation line ~3 is connected to this line with a ventilation valve 34. ~urLhermore a gas pressure me2surins line 35 opens into the furnace chamber 7 and leads to a measuring device 36 constructed as a pressure-flo~ con~erter which supplies the gas pressure in the furn2ce chamber 7 registered thereby via the line 35 in the form Gf electrical signals to an electrical control device 37 which is arranged for controlling the valves 11,18,26 and 34.
The mode of operation or the control de~ice of this exemplary embodiment of the invention operates as follows:
~irst the probe 13 is adjusted to a height within the probe chamber 10 whicn approximately corresponds to the outlet opening of the riser tube 2 in the region of its coupling _lange 3. The changeo~er valve 18 is so switched that the upper probe cha~ber is ventilated. Then with closed ventilation valve 34 with appropriate setting of the control valves 26 in the branch lines 20 to 25 of the pressure gas feed lines 19 pressure gas is introduced into the furnace chamber 7 until the metal melt in the probe chhmber 10 has been pressed up to the lower edge of the contact probe 13 by the gas pressure established thereby abo~e the metal melt in the furnace chamber.
The onset of contact between the highly pressurized metal melt and the contact probe 13 is registered thereby and reported to the electrical control device 37 which then causes further control of the pressure gas flow 19 into the furnace chamber according to a 9 2~3~22 predetermined programme. Simultaneously, the probe 13 is raised by t~e drive cylinder 12 to a height within the probe chzmber 10 at which it remains o~t of contact ~ith the high pressure casting material in the probe chamber throughout the entire following casting process and the changeover valve 18 is switched so th2t the ventilation opening of upper probe chamber is closed znd the pressure equalization line 17 is ~?ened, whereby the gas pressure in the furnace chzmber 7 is diverted to the probe chamber 10 above the metal melt located there and the rising metal melt in this chamber is pressed back to the level of the melt located in the furnace chamber 7.
Moreover, the gas pressure obtaining in the furnace chzmber 7 at this time is measured by the measuring device and its measuring resul~ is electrically supplied to the electrical control device 37 which uses the instantaneously given level of gas pressure in the furnace chamber 7 as reference guantity for further control of the casting pressure in the furnace ch~mber.
~rom this time, the further temporal control and regulation of the casting pressure and thus the rising speed and rising level of the metal melt to be introduced through the riser tube 2 into the hollow mold chamber 6 of the chill mold 5 is performed by control over time of the volume flow of the pressure gas to be introduced into the furnace chamber 7 via the pressure gas line 19 according to a pre-programmed pressure-time curve 38, as may be seen from Fig. 2.
2~3322 The numbers located in rectangles in Big. 2 designa.e measuring points a~ which in the course of a casting cycle the pressure C25 inflow and thus the further time variaticn o~ ~he ~ressure increzse in the furnace chamber experiences ch~nge. The first curve section located be.ween measuring points 1 and 2 shows .he increase of the c2s pressure up to the time at which the metal melt has reached the contact probe 13 in the probe ch~mber 10 set at the height of the coupling flange 3 of the riser tube 2 (level line A). During this phase of pressure increase in the furnace, all control valves 20 to 25 are open in the gas pressure feed line 19. ~his pressure build-up phase is followed by the ph2se of be~inning filling of the hollow mold chamDer 6 in the chill mold 5 which is char2cterized by the curve section between the measuring points 2 znd 3 OI the pressure-time curve according to ~ig. 2. The pressure increase per unit time is somewhat smaller than in the preceding pressure build-up phase 25 appears from ~ig. 2.
This is followed by the main mold filling phase which is chaxacterized by the curve section between the measuring points 3 and 4 in Fig. 2, whereafter the phase of the end of mold filling with further pressure increase according to the curve section between measuring points 4 and 5 takes place until the hollow mold chamber 6 is completely filled (level line B). This phase is follcwed with further strong pressure increase by the re-pressurizing ph2se which is characterized by the curve section between the measuring points 5 and 6, and then the phase of maintaining the increased pressure serving for topping up the mold which is characterized by the curve section between the measuring points 6 and 7.
~5 2 ~ 2 At the end of the re-pressurizing phase, by opening of the ventilation valve 34, the gas pressure in the furnace ch~mber 7 is reduced to zero, ~hich is represented in Fig. 2 by the curve section between the measuring points 7 and B. In this connection, the still liquid metal falls from .he casting passage and riser tube into the furnace.
According to the size of the desired pressure build-up in the curve sections between the measuring points 1 to 6, the control v21ves 26 are opened or closed in various combinations such as results from the following example:
Table Control valves Curve Sections 1 2 3 4 5 6 1-2 + + + + + + Pressure increase (Metal rises to the contact probe) 2-3 - + - - + + Beginning of mold filling 3-4 + - _ _ _ Mold filling 4_5 + + - - + + ~nd of mold filling 5-6 + + - + ' + Increase of re-pressurization 6-7 - - - - - - Maintenance of the re-pressurization 7-8 - - - - - - Ventilation (pressure reduction to atmospheric pressure) 35 _ + = control valve open _ e control valve closed - 12 - 2~3~22 The control ~alves rem2in in the individual phases of the casting cycle in their set position until the gas pressure me2sured coIltinuously by the measurins de~ice 36 in the ~urnace chzmber 7 has reached the respective pre-set desired pressure according to the control programme The regul2tion and leak loss valve 26 located in the branch 25 serves for maintaining the re-pressuriza.ion ,or .he durztion of the above-mentioned topping-up phase, which valve continuously permits a determined amount of pressure gas to flow into the furnace interior chamber 7 according to leakages _in the entire gas pressure system determined according to the gas pressuxe measurement Monitoring of the constancy of the gas pressure during the re-pressurization phase can sex~e to register changes in the overall leakage losses and to effect compensation by appropriate further regulation of the 1055 equalization
THE MOULD FILLING RATE AND CASTING PRESSURE OF A
LOW-PRESSURE CHILL CASTING MACHINE
The invention relates to 2 device and a method for controlling and regulating the mold filling speed and the casting pressure of a low pressure chill casting machine, preferably fo- aluminium casting, whose hermetically closable furnace chamber or container for receiving the liquid casting material can be connected to the chill mould via a riser pipe leading thereto, via which the casting material is forced into the chill mold by means of gas pressure established in the furnzce chamber OI container via a gas supply line, at leas L one contact probe being arranged at an adjustable height in a probe chamber extending into the furnace chamber or container ~rom above and being open at its lower end for the entry of the casting material, which probe supplies a signal to a device for controlling the gas supply flow to the furnace chamber on contact with the casting material rising in the probe chamber as a result of the gas pressure.
Such a control device using at least one contact probe is already known (DE-AS 28 08 588). In this known device, a contact probe, likewise adjustable as to heigh , is used to control and regulate the gas pressure in the furnace chamber ove- the entire _ 2 - 2~a39~
casting cycle. The c~ntact probe has there two sensing needles having sensing points located at differing heights. The pressure qas inflow to the ,urnace chamber or container of the casting material is regulated in such marner that the li~uid level of S the casting materi21 in the probe ch2mber integrated in the riser tube is maintained between the lower and the upper sensing poin,s of the contact probe, the probe bein~ adjusted in height according to the desired gas pressure in the furnace chamber or container.
This known device has the disadvantage that during each casting process the sensing points- of the contact probe make multi~le or even continual contact with the liquid casting material or dip into this, whereby the contact probe rapidly loses its functional precision as a result of adhesion of residues and oxides of the casting material or as a result of attack by the casting material. ~oreover, for the probe chamber as a result of the cyclically rising and falling melt therein the danger exis~s of accretion by melt crystallizing out from the casting material, so that this chamber is heated just as strongly as the riser tube and must be maintained functional by regular cleaning.
Devices are also known for regulating the casting pressure in low pressure chill casting machines (DE-AS 23 31 956) in which the gas pressure in the furnace chamber or in the container for the liquid casting material is adjusted and regulated under computer control according to a predetermined pressure/time curve. The pressure gas is fed in through two gas inlets with differing flow ~ 3 ~ 2~33~22 cross-section. In ~_his connection, several contact probes are provided which are immovably arranged along the path of the riser tube of the casting ma~erial znd by msans of complicated pneumatic regulation me~be s effec. partial or complete opening or closure of the two gas inlets and thus ensure a regulatable gas pressure over wide limits according to the pre-set control. These contact probes are reinserted in each casting cycle into the liquid high pressure casting material extending up to or beyond the~, so that they are 2ssociated with the same disadvantage 25 the probe in the first mentioned known device.
The invention is therefore based on the object, with a device and method of the type initially mentioned, of maintaining unch2nged the functionality of the contact probe over a large number of casting cycles and thus excluding malfunctions in th~ control of the casting pressure, and arranging the control of the pressure gas feed introduced through the probe in a manner which is constructively as simple and operationally reliable as possible. This is achieved according to the invention in that upon contact with the casting material rising in the probe chamber as a result of the gas pressure, upon which it gives a signal to a device for controlling the gas pressure flow to the furnace chamber or container, the contact probe is movable in the probe chamber receiving it to a position of height such that it is not reached during the casting process by the level of the casting material, and in that a measuring arrangement is provided for measuring the gas pressure prevailing in the upper region of the furnace chamber or container for the casting material which provides the measured gas pressure in the form of a signal to the arrangement for controlling the gas pressure flow.
~ 4 ~ 2~922 The contact prcbe thus comes into operation only once during a c2sting cycle signalling the onset of contact .o the arra~gement for control of the gzs pressure flow, w~ereby the sequence of further control znd resulation of .he ~as pressure in the furnace ch2mber or container can be initiated as a function of time according to a predetermined programme. In this connection, the gas pressure measured at this ins.ant by the measuring arrangement in the furnace chcmber or container can be used as a reference pressure for the further control sequence.
~or further control of the gas pressure in the - furnace chamber, the gas pressure given in the furnace chamber or container with the provided measuring arran~ement can be continually re-measured and accordins to the respectively measured actual pressure and the desired pressure- pre-set by the control device the gas pressure flow to the furnace chamber or container can be controlled.
The short contact only once during an entire casting cycle between the contact probe and the high pressure casting material in the probe ch~mber given in the device according to the invention and this method ensures that the contact probe is largely protected and is maintained free of encrustation with casting material.~
The contact probe can be adjustable to such a height in the probe chamber that its sensing points lie approximately on the level of the outlet opening of the riser tube which can be connected to the chill mould. This height corresponds approximately to the level of casting material shortly before the beginning of mold filling, thus to a level which is located slightly beneath the mould cavity.
- - s - 2~ 22 Expediently, the probe chæmber, with the exception of its lower opening for the entry of the casting material, is hermetically closable so that above the casting materizl rising in this chamber a gas pressure can be generated which reliably prevents rising of the casting ma.erial to the contact probe at its raised position. ~o- this purpose, the probe chamber can be in connection in its upper region with the furnace chzmber or container for the liquid casting material Vi2 a pressure gas equalization line prodivided with a closure valve. This closure member can be 2 changeover valve which is controllable in such-manner that at the beginning of a casting cycle it is first open to the .upper probe chamber for external air (ventilating position) and closes the ventilation opening upon the onset of contact of ~he contact probe with the high pressure casting material in the probe chæmber and opens the pressure equalization line to the furnace chamber and thus per~orms gas pressure e~ualization between the probe chamber and the furnace ch~ber.
~or control of the gas pressure in the furnace chamber, the aperture cross-section of the pressure gas line is expediently adjustable in depenàence on the gas pressure preset in the furnace chamber or container by the control programme. In order to ensure setting of the aperture cross-section and thus the amount of gas pressure fed into the furnace chamber with the simplest possible control member, in a preferred embodiment the gas pressure feed line is divided into several branch lines which are brought together again before discharging into the furnace chamber or container and each having an unchangeable aperture cross-section, preferably in the form of a calibrated aperture, for the gas pressure as well as - 6 - ~ 22 a closure val~e. ~he calibrated apertures can have differing aperture openinss and be individually opened or closed in arbitr2ry combination by the arrangement for controlling the gas pressure inflow, whereby the respectively recuired pressure gas inflow to the furnace or container which is responsible for the increasing speed of the czsting material in the riser tube can be precisely controlled. This simple closins and opening control is cheap, technically unproblematical and ~ery unlikely to fail.
In Fig. 1 of the drawings is represented a particularly advantageous exemplary embodiment of the control device accoràing to the invention in a low pressure casting apparatus for aluminium casting lS which wlll be described in more detail in the following.
Fig. 2 shows the possible gas pressure control with the device according to the invention in the course of a casting cycle in a pressure time diagram.
The casting apparatus illustrated in ~ig. 1 consists of a metal smelting furnace 1 into which a riser tube 2 obliquely extends to the vicinity of its base, which tube is provided on its outer end with a connection flange 3 for coupling to a connection flange 4 having an inlet opening of a chill mold 5 with molding ca~ity 6. Into the furnace chamber 7, a tubular body 9 open at its lower end 8 likewise extends from above to the region of the base, which body 9 delimits a probe chamber 10 in which an electrical contact probe is arranged to be adjustable in height by means of a drive cylinder 12 controlled pneumatically or hydraulically via a valve 11. This contact probe consists of a contact plate 13 which is supported on a guide rod 14 activated by the drive ~ ~ 7 ~ 2~ 22 cylinder 12. The level of the casting material, the metal melt, located in the metal smelting furnace 1 is indiczted wi h 15, ~-hich ma~erial can be filled into the f~rn2ce chæmber 7 through a closable inlet 16. 3y means of the dri~re cylinder 12, the probe 13 c~n be adjusted and changed in height in the probe chamber 10 ~-ith ~he guiàe rod 14.
The probe chz~e- 10 -eceiving the probe 13 is hexmetically sealed with the exception of its lower entry opening 8 or the casting material, the inlet of a gas pressure equalization line 17 leading to the furnace chamber 7 and a ventilation opening in .he changeover valve 18. ~n the vicinity of the pressure equalization line 17, a pressure gas line 19 discharges into the furnace chamber. This pressure gas line is sub-divided into six branch lines 20 to which are combined together before discharge into the furnace chamber 7 and each of which has an open-shut control valve 26. The branch lines 20 to 24 are furthermore provideà with calibrated apertures 27 to 31 determining ~he flow of the gas volume, whicn have differing aperture cross-sections. The lines 20 to 25 proviàed with the calibrated apertures can be opened by their control ~alves 26 individually or in arbitrary combination, so that thereby the respectively necessary ~olume of pressure gas for the necessary speed increase in the riser tube 2 can be introduced through the gas feed line 19 into the furnace chamber 7~ The control valve 26 in the branch line 25 serves in conjunction with the choke valve 32 also arranged in this branch line moreover for regulation of the leakage equalization.
- 8 - 2~39~2 In order that the pressure gas feed line 19 can also be used for ~n,ila.ing the furnace chamber 7, a ventilation line ~3 is connected to this line with a ventilation valve 34. ~urLhermore a gas pressure me2surins line 35 opens into the furnace chamber 7 and leads to a measuring device 36 constructed as a pressure-flo~ con~erter which supplies the gas pressure in the furn2ce chamber 7 registered thereby via the line 35 in the form Gf electrical signals to an electrical control device 37 which is arranged for controlling the valves 11,18,26 and 34.
The mode of operation or the control de~ice of this exemplary embodiment of the invention operates as follows:
~irst the probe 13 is adjusted to a height within the probe chamber 10 whicn approximately corresponds to the outlet opening of the riser tube 2 in the region of its coupling _lange 3. The changeo~er valve 18 is so switched that the upper probe cha~ber is ventilated. Then with closed ventilation valve 34 with appropriate setting of the control valves 26 in the branch lines 20 to 25 of the pressure gas feed lines 19 pressure gas is introduced into the furnace chamber 7 until the metal melt in the probe chhmber 10 has been pressed up to the lower edge of the contact probe 13 by the gas pressure established thereby abo~e the metal melt in the furnace chamber.
The onset of contact between the highly pressurized metal melt and the contact probe 13 is registered thereby and reported to the electrical control device 37 which then causes further control of the pressure gas flow 19 into the furnace chamber according to a 9 2~3~22 predetermined programme. Simultaneously, the probe 13 is raised by t~e drive cylinder 12 to a height within the probe chzmber 10 at which it remains o~t of contact ~ith the high pressure casting material in the probe chamber throughout the entire following casting process and the changeover valve 18 is switched so th2t the ventilation opening of upper probe chamber is closed znd the pressure equalization line 17 is ~?ened, whereby the gas pressure in the furnace chzmber 7 is diverted to the probe chamber 10 above the metal melt located there and the rising metal melt in this chamber is pressed back to the level of the melt located in the furnace chamber 7.
Moreover, the gas pressure obtaining in the furnace chzmber 7 at this time is measured by the measuring device and its measuring resul~ is electrically supplied to the electrical control device 37 which uses the instantaneously given level of gas pressure in the furnace chamber 7 as reference guantity for further control of the casting pressure in the furnace ch~mber.
~rom this time, the further temporal control and regulation of the casting pressure and thus the rising speed and rising level of the metal melt to be introduced through the riser tube 2 into the hollow mold chamber 6 of the chill mold 5 is performed by control over time of the volume flow of the pressure gas to be introduced into the furnace chamber 7 via the pressure gas line 19 according to a pre-programmed pressure-time curve 38, as may be seen from Fig. 2.
2~3322 The numbers located in rectangles in Big. 2 designa.e measuring points a~ which in the course of a casting cycle the pressure C25 inflow and thus the further time variaticn o~ ~he ~ressure increzse in the furnace chamber experiences ch~nge. The first curve section located be.ween measuring points 1 and 2 shows .he increase of the c2s pressure up to the time at which the metal melt has reached the contact probe 13 in the probe ch~mber 10 set at the height of the coupling flange 3 of the riser tube 2 (level line A). During this phase of pressure increase in the furnace, all control valves 20 to 25 are open in the gas pressure feed line 19. ~his pressure build-up phase is followed by the ph2se of be~inning filling of the hollow mold chamDer 6 in the chill mold 5 which is char2cterized by the curve section between the measuring points 2 znd 3 OI the pressure-time curve according to ~ig. 2. The pressure increase per unit time is somewhat smaller than in the preceding pressure build-up phase 25 appears from ~ig. 2.
This is followed by the main mold filling phase which is chaxacterized by the curve section between the measuring points 3 and 4 in Fig. 2, whereafter the phase of the end of mold filling with further pressure increase according to the curve section between measuring points 4 and 5 takes place until the hollow mold chamber 6 is completely filled (level line B). This phase is follcwed with further strong pressure increase by the re-pressurizing ph2se which is characterized by the curve section between the measuring points 5 and 6, and then the phase of maintaining the increased pressure serving for topping up the mold which is characterized by the curve section between the measuring points 6 and 7.
~5 2 ~ 2 At the end of the re-pressurizing phase, by opening of the ventilation valve 34, the gas pressure in the furnace ch~mber 7 is reduced to zero, ~hich is represented in Fig. 2 by the curve section between the measuring points 7 and B. In this connection, the still liquid metal falls from .he casting passage and riser tube into the furnace.
According to the size of the desired pressure build-up in the curve sections between the measuring points 1 to 6, the control v21ves 26 are opened or closed in various combinations such as results from the following example:
Table Control valves Curve Sections 1 2 3 4 5 6 1-2 + + + + + + Pressure increase (Metal rises to the contact probe) 2-3 - + - - + + Beginning of mold filling 3-4 + - _ _ _ Mold filling 4_5 + + - - + + ~nd of mold filling 5-6 + + - + ' + Increase of re-pressurization 6-7 - - - - - - Maintenance of the re-pressurization 7-8 - - - - - - Ventilation (pressure reduction to atmospheric pressure) 35 _ + = control valve open _ e control valve closed - 12 - 2~3~22 The control ~alves rem2in in the individual phases of the casting cycle in their set position until the gas pressure me2sured coIltinuously by the measurins de~ice 36 in the ~urnace chzmber 7 has reached the respective pre-set desired pressure according to the control programme The regul2tion and leak loss valve 26 located in the branch 25 serves for maintaining the re-pressuriza.ion ,or .he durztion of the above-mentioned topping-up phase, which valve continuously permits a determined amount of pressure gas to flow into the furnace interior chamber 7 according to leakages _in the entire gas pressure system determined according to the gas pressuxe measurement Monitoring of the constancy of the gas pressure during the re-pressurization phase can sex~e to register changes in the overall leakage losses and to effect compensation by appropriate further regulation of the 1055 equalization
Claims (13)
1. Device for controlling and regulating the mold filling speed and casting pressure of a low pressure chill casting machine, whose hermetically closable furnace chamber receiving the casting material is connected to the chill mold via a riser tube leading to this, via which the casting material is pressed into the chill mold by means of gas pressure established in the furnace chamber via a pressure gas feed line, at least one contact probe being arranged at an adjustable height in a probe chamber extending into the furance chamber from above and being open at its lower end for the entry of the casting material, which probe provides a signal to an arrangement for controlling the pressure gas inflow on the onset of contact with the casting material rising in the probe chamber as a result of the gas pressure, characterized in that on onset of contact the contact probe (13) is adjustable in the probe chamber (10) to a height position which is not reached during the casting process by the level of liquid casting material, and in that a measuring arrangement (36) is provided for measuring the gas pressure in the furnace chamber (37) which arrangement provides the measured pressure in the form of a signal to an arrangement (37) for controlling the pressure gas inflow.
2. Device according to claim 1 characterized in that the contact probe (13) is movable in and out by a pneumatically or hydraulically controlled drive cylinder (12).
3. Device according to claim 1 characterized in that the contact probe (13) is adjustable in the probe chamber (10) to a height position such that its sensing points lie approximately at the height of the outlet opening of the riser tube (2) connectable to the chill mold (5).
4. Device according to claim 1 characterized in that the probe chamber has a closable ventilation opening in its upper region.
5. Device according to claim 1 or 4 characterized in that the probe chamber (10) can be hermetically sealed with the exception of its lower opening end (8) for the entry of the casting material.
6. Device according to claim 4 characterized in that the probe chamber (10) is connected at its lower region to the furnace chamber (7) via a pressure gas equalization line (17) closable by a changeover valve (18).
7. Device according to claim 4 and 6 characterized in that the changeover valve (18) is controllable in such manner that upon onset of contact of the contact probe (13) with the high pressure casting material in the probe chamber (10) it switches such that the ventilation opening of the probe chamber is closed and the pressure equalization line (17) is open.
8. Device according to claim 1 characterized in that the aperture cross-section of the pressure gas feed line (19) can be changed in dependence upon the desired gas pressure in the furnace chamber.
9. Device according to claim 8 characterized in that for setting the desired gas pressure in the furnace chamber (7) the gas pressure feed line (19) is sub divided into a plurality of branch lines (20 to (25) which are brought together again before discharge into the furnace chamber end which have respective fixed aperture cross-section (calibrated apertures 27 to 31) for the pressure gas end a control valve (26) constructed as an open-shut valve.
10. Device according to claim 9 characterized in that the control valves are controllable by an arrangement (37) for controlling the pressure gas feed flow.
11. Device according to claim 1 characterized in that in the pressure gas feed line (19) discharging into the furnace chamber (7) a leak valve (26,32) is arranged which is controllable in dependence upon the gas pressure losses caused by leakage as measured in the furnace chamber.
12. Method for controlling the casting pressure of a low pressure chill casting apparatus (metal casting apparatus) comprising a device according to one or more of claims 1 to 11 characterized in that on the onset of contact of the contact probe with the high pressure casting material in the probe chamber the gas pressure in the furnace chamber is measured and via an electrical signal is used as reference pressure for further control of the pressure gas feed flow to the furnace chamber.
13. Method according to claim 12 characterized in that after onset of contact of the contact probe with the high pressure casting material in the probe chamber the gas pressure in the furnace chamber is continually measured and the gas pressure feed flow to the furnace chamber is controlled according to the respective desired pressure in the furnace chamber pre-set by the control programme.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE3924775A DE3924775C1 (en) | 1989-07-26 | 1989-07-26 | |
| DEP3924775.9 | 1989-07-26 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2053922A1 true CA2053922A1 (en) | 1991-01-27 |
Family
ID=6385907
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002053922A Abandoned CA2053922A1 (en) | 1989-07-26 | 1990-07-25 | Process and device for controlling and regulating the mould filling rate and casting pressure of a low pressure chill casting machine |
Country Status (14)
| Country | Link |
|---|---|
| EP (1) | EP0483191B1 (en) |
| JP (1) | JPH04506934A (en) |
| KR (1) | KR920700811A (en) |
| AT (1) | ATE89773T1 (en) |
| AU (1) | AU6043590A (en) |
| BR (1) | BR9007556A (en) |
| CA (1) | CA2053922A1 (en) |
| DD (1) | DD295571A5 (en) |
| DE (2) | DE3924775C1 (en) |
| DK (1) | DK0483191T3 (en) |
| ES (1) | ES2040600T3 (en) |
| MY (1) | MY106433A (en) |
| PT (1) | PT94821A (en) |
| WO (1) | WO1991001833A1 (en) |
Families Citing this family (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| AT396439B (en) * | 1991-05-13 | 1993-09-27 | Sommerhuber Franz | Apparatus for permanent-mould casting of sections of large dimensions, in particular hollow sections, from light alloy |
| FR2705044B1 (en) * | 1993-05-10 | 1995-08-04 | Merrien Pierre | LOW PRESSURE PILOT CASTING PROCESS OF A VACUUM MOLD FOR ALUMINUM OR MAGNESIUM ALLOYS AND DEVICE FOR ITS IMPLEMENTATION. |
| DE19821419A1 (en) | 1998-05-13 | 1999-11-18 | Georg Fischer Disa Ag | Process for increasing low pressure casting of metal, especially light metal |
| DE19834553A1 (en) * | 1998-07-31 | 2000-02-03 | Georg Fischer Disa Ag | Method and device for increasing the casting of light metal |
| DE19905874C2 (en) * | 1999-02-12 | 2003-07-24 | Vaw Alucast Gmbh | Device for filling molds |
| DE10061026A1 (en) * | 2000-12-08 | 2002-06-13 | Bayerische Motoren Werke Ag | Metal casting process and device |
| DE10352179B4 (en) * | 2003-11-05 | 2007-09-06 | Dihag Deutsche Giesserei- Und Industrie-Holding Ag | Low pressure casting process for the production of a casting |
| JP5073392B2 (en) * | 2007-07-11 | 2012-11-14 | 東京窯業株式会社 | Ladle |
| CN102211170A (en) * | 2011-05-20 | 2011-10-12 | 江苏天宏机械工业有限公司 | Highly turbocharged low pressure die casting machine |
| US8327915B1 (en) * | 2011-05-25 | 2012-12-11 | GM Global Technology Operations LLC | Pour ladle for molten metal |
| CN108620557A (en) * | 2018-05-25 | 2018-10-09 | 东莞市镁正隆工业熔炉设备有限公司 | A kind of alloy die cast feed delicate metering equipment and its working method |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4153100A (en) * | 1975-10-27 | 1979-05-08 | Institut Po Metaloznanie I Technologia Na Metalite | Low-pressure or counterpressure casting apparatus |
| FR2382298A1 (en) * | 1977-03-01 | 1978-09-29 | Renault | LOW PRESSURE LIQUID METAL CASTING DEVICE |
| US4585050A (en) * | 1981-01-05 | 1986-04-29 | Etude Et Developpement En Metallurgie, E.D.E.M., S.A.R.L. | Process for automatic regulation of a casting cycle |
-
1989
- 1989-07-26 DE DE3924775A patent/DE3924775C1/de not_active Expired - Fee Related
-
1990
- 1990-07-25 AU AU60435/90A patent/AU6043590A/en not_active Abandoned
- 1990-07-25 BR BR909007556A patent/BR9007556A/en unknown
- 1990-07-25 DK DK90910641.1T patent/DK0483191T3/en active
- 1990-07-25 ES ES199090910641T patent/ES2040600T3/en not_active Expired - Lifetime
- 1990-07-25 JP JP2510299A patent/JPH04506934A/en active Pending
- 1990-07-25 AT AT90910641T patent/ATE89773T1/en active
- 1990-07-25 EP EP90910641A patent/EP0483191B1/en not_active Expired - Lifetime
- 1990-07-25 MY MYPI90001247A patent/MY106433A/en unknown
- 1990-07-25 CA CA002053922A patent/CA2053922A1/en not_active Abandoned
- 1990-07-25 DD DD90343060A patent/DD295571A5/en not_active IP Right Cessation
- 1990-07-25 KR KR1019910701516A patent/KR920700811A/en not_active Withdrawn
- 1990-07-25 WO PCT/EP1990/001223 patent/WO1991001833A1/en not_active Ceased
- 1990-07-25 DE DE9090910641T patent/DE59001574D1/en not_active Expired - Fee Related
- 1990-07-26 PT PT94821A patent/PT94821A/en not_active Application Discontinuation
Also Published As
| Publication number | Publication date |
|---|---|
| JPH04506934A (en) | 1992-12-03 |
| ES2040600T3 (en) | 1993-10-16 |
| DK0483191T3 (en) | 1993-06-21 |
| WO1991001833A1 (en) | 1991-02-21 |
| EP0483191A1 (en) | 1992-05-06 |
| AU6043590A (en) | 1991-03-11 |
| BR9007556A (en) | 1992-06-23 |
| ATE89773T1 (en) | 1993-06-15 |
| DD295571A5 (en) | 1991-11-07 |
| DE59001574D1 (en) | 1993-07-01 |
| MY106433A (en) | 1995-05-30 |
| KR920700811A (en) | 1992-08-10 |
| EP0483191B1 (en) | 1993-05-26 |
| DE3924775C1 (en) | 1990-03-29 |
| PT94821A (en) | 1991-03-20 |
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Legal Events
| Date | Code | Title | Description |
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| FZDE | Discontinued |