US3748858A - Apparatus for controlling the pressure at the input of casting machines - Google Patents

Apparatus for controlling the pressure at the input of casting machines Download PDF

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Publication number
US3748858A
US3748858A US00205920A US3748858DA US3748858A US 3748858 A US3748858 A US 3748858A US 00205920 A US00205920 A US 00205920A US 3748858D A US3748858D A US 3748858DA US 3748858 A US3748858 A US 3748858A
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United States
Prior art keywords
pressure
medium
counterpressure
chamber
multiplier
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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.)
Expired - Lifetime
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US00205920A
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English (en)
Inventor
W Venus
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Gusstahlwerke Wittmann AG
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Gusstahlwerke Wittmann AG
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D17/00—Pressure die casting or injection die casting, i.e. casting in which the metal is forced into a mould under high pressure
    • B22D17/20—Accessories: Details
    • B22D17/32—Controlling equipment
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
    • B29C45/17—Component parts, details or accessories; Auxiliary operations
    • B29C45/76—Measuring, controlling or regulating
    • B29C45/82—Hydraulic or pneumatic circuits

Definitions

  • the present invention relates to an apparatus for controlling the pressure at the input of casting machines particularly for die casting machines, having a multiplier cylinder that is divided by a multiplier piston into a feed chamber and a counterpressure chamber, the counterpressure chamber being filled with a counterpressure medium.
  • An apparatus of the above-described type is used in casting machines, particularly die casting machines, in order to subject the casting material, e.g. an alloy, to increased pressure from the time it has been pressed into the mold cavity until it subsequently hardens.
  • the feed chamber of the multiplier cylinder is connected, at a very precisely controlled time, with a pressure reservoir so that the multiplier piston exerts a substantial increased pressure onto the die moving the casting material.
  • the effect of the pressure multiplier must be appropriately controlled. This is generally done in the apparatus of the type described above by adjusting the counterpressure acting on the multiplier piston.
  • the counterpressure which acts on the multiplier piston and determines the effective multiplier effect, is produced in the pressure setting valve as a direct result of the passage of pressure fluid through predetermined cross sections in the valve, i.e. as a consequence of this pressure fluid being choked off.
  • the cross-sectional areas are produced and maintained by appropriate charging of the regulating and control elements.
  • the counterpressure set in the pressure control valve thus is produced, at the earliest, only after a stream of pressure fluid has formed in the pressure setting valve.
  • the counterpressure set in the pressure setting valve is influenced by the speed of the multiplier piston. Consequently the appropriately adapted and modified cross-sectional area must always be formed in the pressure setting valve to be adaptable to a changed throughput of pressure fluid per unit time.
  • Embodiments are also known in which the counterpressure chamber of the multiplier is connected with the liquid chamber of a pressure reservoir and with a check valve disposed in the connecting line. This arrangement, however, neither prevents the delays in starting caused by the inertial resistances of the moved masses nor the influences on the counterpressure by the variable speed of the multiplier piston, which influences are determined by the valve cross sections.
  • the above described object of the invention is accomplished in that the counterpressure chamber is in communication, via a connecting line which produces as low a choking effect as possible, with a pressure container to receive the counterpressure medium directly from the container.
  • the counterpressure medium is maintained at an appropriately set permanent pressure in the counlittle choking effect as possible, it is advisable to select a connecting line between the counterpressure chamber and the pressure container which has a particularly large cross section.
  • a gas e.g. nitrogen
  • the counterpressure medium is used in contradistinction to the known devices, as the counterpressure medium.
  • nitrogen is used as the counterpressure medium instead of oil
  • the ratio of the mass inertia of the mediums is about
  • the effective volume of the pressure container holding the counterpressure medium is made to be variable. In one embodiment the effective volume of the pressure container is varied by the addition of pressure medium from the drive system of the casting machine or by removal therefrom into the tank of the drive system.
  • the feed chamber receives pressure medium from a pressure reservoir via two parallel valves which open consecutively.
  • the combination of two valves affords the opportunity to achieve those conditions, which best meet the requirements of the desired die casting operation by the appropriate selection of the moments when the valves open. These requirements relate, for example, to the escape of air from the mold cavity and the fill chamber and to a rapid filling of the mold cavity with a pressure increase which starts immediately thereafter before the cast material hardens.
  • FIGURE of the drawing is a partly schematic and partly simplified cross-sectional view of the apparatus, according to the present invention, associated with a cold chamber die casting machine having a horizontal pressure chamber.
  • FIGURE shows a pressure plunger 2 displaceably disposed in a known manner in the till or pressure chamber 1, this plunger exerting a pressing force on the casting material introduced into chamber 1 at opening 1a, to press it into a mold cavity 3.
  • the mold halves of the mold which form the mold cavity 3 are indicated at 4 and 5.
  • Mold half 4 rests on a firm mold clamping plate 6 while the movable mold half is pressed, via a clamping box 7, against the fixed mold half 4 by a mold locking mechanism which is not shown.
  • the pressure force exerted on the casting material is transmitted to the pressure plunger 2 via a die rod 8 which is connected to a press piston 9.
  • the press piston 9 is displaceable in a press cylinder 10 which is associated with a multiplier cylinder 11.
  • a multiplier piston 14 is displaceable in multiplier cylinder 11 and can charge the interior of press cylinder 10 with pressure via a multiplier piston shaft 13.
  • a stepped opening or bore 15 extends through multiplier piston 14 and piston shaft 13 and this opening is closed at its end facing the press cylinder 10 by a spring loaded check valve 16.
  • This check valve 16 permits passage of pressure medium into press cylinder 10 when a certain pressure value in the feed chamber 12 of the multiplier cylinder 11 is exceeded.
  • the feed chamber 12 of the multiplier cylinder 11 is in communication with a pressure reservoir 23 via lines 19 and 20 containing control valves generally indicated at 21, 22.
  • a separating piston 24 is shown disposed in pressure reservoir 23 but the reservoir 23 may, of course, also be designed without a separating piston.
  • the reservoir is charged by the pump (not shown) of the drive system of the casting machine via pressure lines 31, 17, 25 and 20.
  • Line 25 has a switched-on check valve 26.
  • the counterpressure chamber 18 of the multiplier cylinder 11 is in communication, via line 27, with a pressure tank 28.
  • the tank can be charged and discharged through the blocking valve 39.
  • the pressure tank 28 itself is connected, via lines 29 with a blocking valve 30 included therein, to the pressure line 31 com ing from the pump (not shown). From that portion of the line disposed between the blocking valve 30 and the pressure tank 28 a discharge line 33, which is provided with a blocking valve 32, branches ofi.
  • Pressure lines 31 and 17, charged by the pump of the drive system can be connected selectively, by means of a control slide valve 34, either with the feed chamber 12 of the multiplier cylinder 11, through lines 19 and 19a, or with the return chamber 40 that is disposed opposite the feed chamber 41 of the press cylinder 10.
  • this control slide valve 34 is designed as a direct action or precontrolled magnet slide valve.
  • the control valves 21 and 22 connected between lines 19 and 20 are presettable regarding their opening widths by means of setting spindles 21a or 22a, respectively disposed over the movable members 21' and 22' of the valves.
  • the pressure chambers 35 or 36, respectively, which are disposed above the movable member of the control valves 21 and 22 are in communication either with the pressure reservoir 23 or with the discharge drain via sliding valves 37 or 38, respectively.
  • the pressure tank 28 contains, as the counterpressure medium, nitrogen gas or some other inert gas at a predetermined pressure and the line 27 connecting the pressure tank with the counterpressure chamber 18 has as large a cross section as possible in order to counteract a flow of the nitrogen gas, upon displacement of the multiplier piston 14, with as low as possible a choking action.
  • control device operates as follows. After filling the casting material into the pressure chamber 1 disposed in front of the mold cavity 3, the control slide 34 is changed in its position and pressure medium from the drive system of the casting machine flows from pressure line 31 via line 17, control valve 34 and lines 19a and 19 into feed chamber 12 of the multiplier cylinder 11. From this feed chamber the pressure medium flows through the longitudinal bore 15, and, after lifting check valve 16, into feed chamber 41 of press cylinder 10 to the front of press piston 9. Immediately preceding this, control slide 34 had connected the return chamber 40 in the press cylinder 10 with the discharge drain.
  • control valve 21 is opened by the pressure medium in line 20, at a predetermined point in time. The extent of the opening is determined by presetting of spindle 210.
  • control valve 22 is additionally lifted to the extent previously set by spindle 220. This is done when the sliding valve 38 connects the pressure chamber 36 disposed above the movable member 22' with the discharge drain. The pressure of the medium in pressure reservoir 23 then raises the movable member 22 of control valve 22 quickly to the set opening height. Thus pressure medium flows into the feed chamber in front of the pressing piston 9 not only through control valve 21 but also through control valve 22 and thus further increases the speed of the piston.
  • the continuous pressure of the nitrogen which has been maintained in pressure tank 28 acts on the annular surface of the multiplier piston 14 facing the coun terpressure chamber 18.
  • the term continuous pressure here indicates that this pressure, contrary to the known control devices, is not produced only at a movement of the multiplier piston but rather is present continuously, i.e. also when the multiplier piston 14 is in its rest state.
  • This continuous pressure is selected to be at least high enough that the pressure force exerted by it on the annular surface of the multiplier piston 14 is greater than the pressure force acting on the multiplier piston 14 during passage of the pressure medium of the driving system through check valve 16.
  • the pressure force produced by the pressure medium of the drive system tends to push the multiplier piston 14 to the left as seen in the drawings.
  • connection line 27 Due to the large cross section of connection line 27, the speed of flow of the nitrogen during displacement of the multiplier piston 14 and, thus the flow resistance, remain very low. Moreover, with the selection of nitrogen as the counterpressure medium, only slight delays, caused by the very low mass inertia of the gas, need be anticipated. Thus the counterpressure is almost completely constant in the counterpressure chamber corresponding to the pressure in tank 28 and there is an extraordinary acceleration in the response of the multiplier effect. Therefore it is possible in the very short time interval immediately before or at the point of complete fill of the mold cavity 3, which time interval is so very important, to set a precisely defined multiplier pressure.
  • the pressure in the counterpressure chamber 18 and in the connected pressure tank 28 is changed by charging from a nitrogen supply tank, not shown, via the blocking valve 39 or by release of nitrogen into the atmosphere via this valve.
  • the effective volume of tank 28 can be varied by the addition or removal of pressure medium from the drive system of the casting machine.
  • the pressure medium enters into tank 28 through line 29 and blocking valve 30 and can flow off, if required, through blocking valve 32 and line 33 into the tank of the drive system.
  • the pressure medium in tank 28 has no hydraulic function in the drive system of the machine but rather serves only to vary the effective volume of tank 28, which contains nitrogen, and thus vary the pressure of the nitrogen.
  • the operating range of the press cylinder 10 of the casting machine is set according to the selected size of tank 28. This range is one in which it is possible to set at will any desired final multiplier pressure from a maximum to a minimum merely by the addition or removal of pressure medium.
  • the casting conditions require that the movement of press piston 9 which has been produced only by opening of control valve 21 be continued be yond the point where the casting material reaches the mold gate.
  • the casting material then fills the mold cavity 3 relatively slowly in accordance with the speed of press piston 9. This is of advantage, for example, when, for east objects having a larger wall thickness, the air contained in the mold cavity 3 must be permitted to escape. Only when mold cavity 3 has been filled to a substantial extent or even entirely with casting material, will control valve 22 be opened, which now increases the speed of press piston 9 until mold cavity 3 is completely filled and then moves the multiplier piston 14 correspondingly rapidly in order to effect a rapid pressure increase in the casting material before it hardens.
  • valves 21 and 22 are opened are advisably determined by limit switches, timers or pressure switches. In the extreme case, it is thus possible, without difficulties, to initially displace the casting material in the fill chamber at the speed set in the control valve 21 and then press it into the mold cavity 3 until it completely fills the latter, whereupon it is suddenly charged with the multiplied pressure of the multiplier piston 14 when control valve 22 has fully opened.
  • the pressure-dependent switching of control valve 22 it is also possible to use, for example, a time-dependent circuit so that the control valve 22 opens a predetermined time before mold cavity 3 is filled completely.
  • control valve 22 can in this case most advisably be determined by a pathdependently actuated limit switch.
  • Other suitable types of actuation for opening of control valves 21 and 22 at a defined point in time are of course also possible.
  • the control device according to the present invention has been described only in connection with a cold chamber die casting machine, it is of course understood that the principle of the present invention can be used for any similarly operating casting machine where it is of importance to subject the casting material at a defined moment in time to an increased pressure with the least possible delay and a precisely defined effect.
  • the apparatus according to the present invention can therefore also be used, without restriction, for example, in hot chamber die casting machines or injection molding machines for thermoplastic masses.
  • Control valves 21 and 22 can moreover be so selected that they either have the same dimensions and opening cross sections for flow of the pressure medium or are opened to different extents or have different dimensions and perform the same valve stroke.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Injection Moulding Of Plastics Or The Like (AREA)
US00205920A 1970-12-10 1971-12-08 Apparatus for controlling the pressure at the input of casting machines Expired - Lifetime US3748858A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE19702060681 DE2060681A1 (de) 1970-12-10 1970-12-10 Vorrichtung zur Steuerung des Druckverlaufes am Einpressteil von Giessmaschinen

Publications (1)

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US3748858A true US3748858A (en) 1973-07-31

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Application Number Title Priority Date Filing Date
US00205920A Expired - Lifetime US3748858A (en) 1970-12-10 1971-12-08 Apparatus for controlling the pressure at the input of casting machines

Country Status (7)

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US (1) US3748858A (enrdf_load_stackoverflow)
BE (1) BE774261A (enrdf_load_stackoverflow)
DE (1) DE2060681A1 (enrdf_load_stackoverflow)
FR (1) FR2117853A1 (enrdf_load_stackoverflow)
IT (1) IT943801B (enrdf_load_stackoverflow)
LU (1) LU64158A1 (enrdf_load_stackoverflow)
NL (1) NL7115241A (enrdf_load_stackoverflow)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5479777A (en) * 1994-04-15 1996-01-02 Mednext Inc. Torque and speed control methods and apparatus for pneumatic motors
WO2010070053A1 (de) * 2008-12-17 2010-06-24 Bühler Druckguss AG Anordnung für eine druckgiessmaschine und verfahren zum betreiben eines antriebskolbens der druckgiessmaschine
CN104923758A (zh) * 2014-03-21 2015-09-23 意特佩雷斯工业公司 用于液压压铸机的注入组件

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2747066C2 (de) * 1977-10-20 1979-11-29 Maschinenfabrik Weingarten Ag, 7987 Weingarten Vorrichtung zum Einstellen der Preßkolbengeschwindigkeiten und -drücke bei Druckgießmaschinen mit Drei-Phasen-System, insbesondere bei Kaltkammer-Druckgießmaschinen
DE2801829C3 (de) * 1978-01-17 1985-02-21 Maschinenfabrik Müller-Weingarten AG, 7987 Weingarten Verfahren und Vorrichtung zum Steuern einer Druckgießmaschine
DE3014868A1 (de) * 1979-06-18 1981-01-22 Buehler Ag Geb Druckgiessmaschine

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1460586A (en) * 1922-03-02 1923-07-03 Underfeed Stoker Company Hydraulic drive for stoker rams
US1970999A (en) * 1930-05-31 1934-08-21 Oilgear Co Hydraulic press
US2351872A (en) * 1941-03-31 1944-06-20 Parker Appliance Co Hydraulic press
US2403912A (en) * 1944-01-17 1946-07-16 Link Engineering Co Press operating device
US2597050A (en) * 1942-06-25 1952-05-20 Olaer Marine Hydraulic transmission for reproducing mechanical motions at remote points
US2618822A (en) * 1948-10-01 1952-11-25 Hahn & Kolb System for driving working pistons in die-casting machines or injection molding machines
US3165979A (en) * 1961-02-01 1965-01-19 Clerk Robert Cecil Driving and control mechanisms for power-operated machine tools

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1460586A (en) * 1922-03-02 1923-07-03 Underfeed Stoker Company Hydraulic drive for stoker rams
US1970999A (en) * 1930-05-31 1934-08-21 Oilgear Co Hydraulic press
US2351872A (en) * 1941-03-31 1944-06-20 Parker Appliance Co Hydraulic press
US2597050A (en) * 1942-06-25 1952-05-20 Olaer Marine Hydraulic transmission for reproducing mechanical motions at remote points
US2403912A (en) * 1944-01-17 1946-07-16 Link Engineering Co Press operating device
US2618822A (en) * 1948-10-01 1952-11-25 Hahn & Kolb System for driving working pistons in die-casting machines or injection molding machines
US3165979A (en) * 1961-02-01 1965-01-19 Clerk Robert Cecil Driving and control mechanisms for power-operated machine tools

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5479777A (en) * 1994-04-15 1996-01-02 Mednext Inc. Torque and speed control methods and apparatus for pneumatic motors
WO2010070053A1 (de) * 2008-12-17 2010-06-24 Bühler Druckguss AG Anordnung für eine druckgiessmaschine und verfahren zum betreiben eines antriebskolbens der druckgiessmaschine
CN104923758A (zh) * 2014-03-21 2015-09-23 意特佩雷斯工业公司 用于液压压铸机的注入组件
EP2942127A1 (en) * 2014-03-21 2015-11-11 Italpresse Industrie S.p.A. Die-casting machine with injection assembly with a shut-off valve
CN104923758B (zh) * 2014-03-21 2018-11-06 意特佩雷斯工业单一合伙责任有限公司 用于液压压铸机的注入组件
EP3501691A1 (en) * 2014-03-21 2019-06-26 ITALPRESSE INDUSTRIE S.p.A. Incection assembly provided with a shut-off valve for a die-casting machine

Also Published As

Publication number Publication date
IT943801B (it) 1973-04-10
FR2117853A1 (enrdf_load_stackoverflow) 1972-07-28
BE774261A (fr) 1972-02-14
LU64158A1 (enrdf_load_stackoverflow) 1972-05-12
NL7115241A (enrdf_load_stackoverflow) 1972-06-13
DE2060681A1 (de) 1972-06-15

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