EP0530244B1 - Injection unit for a hydraulic die-casting machine, provided with a device for the elimination of pressure peaks at injection - Google Patents

Injection unit for a hydraulic die-casting machine, provided with a device for the elimination of pressure peaks at injection Download PDF

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Publication number
EP0530244B1
EP0530244B1 EP91909466A EP91909466A EP0530244B1 EP 0530244 B1 EP0530244 B1 EP 0530244B1 EP 91909466 A EP91909466 A EP 91909466A EP 91909466 A EP91909466 A EP 91909466A EP 0530244 B1 EP0530244 B1 EP 0530244B1
Authority
EP
European Patent Office
Prior art keywords
piston
injection
auxiliary
cylinder
accumulator
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.)
Expired - Lifetime
Application number
EP91909466A
Other languages
German (de)
English (en)
French (fr)
Other versions
EP0530244A1 (en
Inventor
Roberto Bragastini
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.)
INTERNATIONAL PRESS DEVELOPMENT ESTABLISHMENT
Original Assignee
INTERNATIONAL PRESS DEVELOPMENT ESTABLISHMENT
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by INTERNATIONAL PRESS DEVELOPMENT ESTABLISHMENT filed Critical INTERNATIONAL PRESS DEVELOPMENT ESTABLISHMENT
Publication of EP0530244A1 publication Critical patent/EP0530244A1/en
Application granted granted Critical
Publication of EP0530244B1 publication Critical patent/EP0530244B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • 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
    • B22D17/2015—Means for forcing the molten metal into the die

Definitions

  • the present invention relates to an injection unit for a hydraulic die-casting machine, provided with a device for the elimination of pressure peaks at injection.
  • such injection units comprise an injection cylinder, an injection piston slidably housed in the cylinder and valve means suitable for sequentially placing in communication with the cylinder first a fluid supply pump for a possible slow advancement stage of the injection piston and subsequently a fluid accumulator for a second fast advancement stage of the injection piston.
  • Such units also comprise a pressure multiplier which has the function of subsequently raising the pressure of the fluid acting on the injection piston for a third short advancement stage at slow speed and high pressure. The latter stage allows the molten metal to reach and fill with adequate compactness the most distant and difficult interstices of the casting cavity.
  • DE-C-3 123 498 discloses an injection unit of this kind, further including an auxiliary cylinder/piston unit associated to the injection cylinder to dampen the pressure peaks caused by the pressure multiplier.
  • the object of the present invention is to overcome this drawback by accomplishing an injection unit in which such pressure peak is eliminated.
  • an injection unit for a hydraulic die-casting machine comprising an injection cylinder, a hydraulically-operated injection piston, a fluid accumulator for the operation at high speed of the injection piston during the injection stroke, a pressure multiplier for the operation at low speed and high pressure of the piston at the end of the injection stroke of the piston and an auxiliary cylinder/piston unit, characterized in that said auxiliary unit is interposed between the injection piston and the accumulator to allow the advancement of the auxiliary piston under the action of the accumulator and the advancement of said injection piston in accordance with that of said auxiliary piston, the cross-section of said auxiliary cylinder being larger than the cross-section of said injection cylinder.
  • the difference between the cross-sections of the injection piston and of the auxiliary piston is such that the auxiliary piston moves at a speed that is lower than that of the injection piston and reaches the end of the stroke in a controlled manner so as to avoid the creation of pressure peaks on the injected metal.
  • the injection unit comprises a high-speed accumulator 1 consisting of a cylindrical chamber 14 in which a piston 15 slides.
  • the upper part of the cylindrical chamber 14 is filled with nitrogen 2 under pressure from a cylinder 19, while the lower part is filled with fluid 30 which, pushed by the piston 15, through a connecting conduit 5, under the action of valve means constituted by a valve shell 31 and by a variable-action breech 32, causes the advancement of a piston 7 of an auxiliary cylinder/piston unit 6, 7 provided with a linear speed transducer 71.
  • the cylindrical chamber 6 is filled in the front with fluid 40 which, pushed in a conduit 8 provided with a unidirectional valve 60 by the movement of the piston 7, causes the advancement of an injection piston 10 into a corresponding injection cylinder 9 provided with a rapid discharge valve 65 (of a type known in itself).
  • a pressure multiplier 12 With the injection cylinder/piston unit 9, 10, provided with an injection stem 42, there is connected through a line 11, provided with a unidirectional valve 61, a pressure multiplier 12.
  • the latter comprises an accumulator 13 consisting of a cylinder/piston 16, 17.
  • the upper part of the cylindrical chamber 16 is filled with nitrogen under pressure 18 which causes the sliding action of the piston 17, while the lower part of the chamber 16 is filled with fluid 50 which, pushed by the piston 17, through the line 51 under the action of valve means constituted by a valve shell 20 and a variable-action breech 21, causes the advancement of a cylinder/piston pair 53, 52 which in turn with fluid 54 causes the sliding action of the injection piston 10 in the corresponding cylinder 9.
  • the molten mass present in the injection cylinder 9 is compressed by the stem 42 in the proximity of the injection mouth (not shown).
  • the larger diameter of the auxiliary cylinder 6 with respect to the injection cylinder 9 causes the speed of the auxiliary piston 7 during its stroke to be lower than that of the injection piston 10 and thus easily controllable.
  • the action of the pressure multiplier 12 then follows in a controlled manner. As illustrated in Fig. 3, in this stage the piston 17, pushed by the nitrogen under pressure 18 present in the upper part of the cylinder 16, starts its stroke and pushes the fluid 50 into the line 51 under the action of the valve means 20, 21 and, through the cylinder/piston pair 53, 52 and the corresponding control fluid 54, causing the sliding action with the multiplication of the pressure of the injection piston 10 in the corresponding cylinder 9.
  • auxiliary piston 7 also operates in the ambit of the pressure multiplier 12.
  • the piston 7 has a part with a smaller diameter which co-operates with the cylinder 6 supplied with fluid 30 from the accumulator 1 through a unidirectional valve 85 and communicating with the injection cylinder 9 through a valve 87 with a floating breech 88 and a part with a larger diameter which co-operates with a cylinder 86 supplied with fluid 50 from the accumulator 13 through the valve 20 with controlled breech 21 and communicating with the injection cylinder 9 through the unidirectional valve 61.
  • Fig.s 5 - 8 also show two unidirectional valves 91 and 92 destined to the supply of fluid under pressure for recharging the accumulators 1 and 13 and a valve 93 with a floating breech 94 for discharging the fluid sent back by the injection piston 10 during the stages when it returns to the at rest position.
  • the movement of opening of the breech 32 causes the supply of fluid 30 through the unidirectional valve 85 into the cylinder 6, where the piston 7 is thus caused to move forward so that, in turn, through the unidirectional valve 61, it causes the advancement of the injection piston 10 inside the injection cylinder 9 (with the valve 65 open) for the stage of injection of the metal into the casting cavity (Fig. 6).
  • the breech 21 is caused to open, allowing the transfer of high-pressure fluid from the accumulator 13 to the auxiliary cylinder 86, where the above fluid causes the auxiliary piston 7 to move backward and, due to the difference in area, the consequent creation of a multiplied pressure in the cylinder 6, which opens the valve 87 and goes to supply the injection piston 10 (Fig. 7). This creates the pressure multiplier effect on the molten metal pushed by the piston stem 42.
  • valves 31, 32 and 21, 10 close again and thanks to the valve 65 the injection piston 10 is caused to return, thus discharging fluid through the valve 93 (Fig. 8).

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Injection Moulding Of Plastics Or The Like (AREA)
  • Moulds For Moulding Plastics Or The Like (AREA)
  • Molds, Cores, And Manufacturing Methods Thereof (AREA)
  • Fluid-Pressure Circuits (AREA)
EP91909466A 1990-05-22 1991-05-15 Injection unit for a hydraulic die-casting machine, provided with a device for the elimination of pressure peaks at injection Expired - Lifetime EP0530244B1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
IT02039490A IT1248476B (it) 1990-05-22 1990-05-22 Gruppo di iniezione per macchina idraulica per pressofusione, munito di dispositivo per l`eliminazione di picchi di pressione all`iniezione
IT2039490 1990-05-22
PCT/EP1991/000913 WO1991017850A1 (en) 1990-05-22 1991-05-15 Injection unit for a hydraulic die-casting machine, provided with a device for the elimination of pressure peaks at injection

Publications (2)

Publication Number Publication Date
EP0530244A1 EP0530244A1 (en) 1993-03-10
EP0530244B1 true EP0530244B1 (en) 1996-01-10

Family

ID=11166319

Family Applications (1)

Application Number Title Priority Date Filing Date
EP91909466A Expired - Lifetime EP0530244B1 (en) 1990-05-22 1991-05-15 Injection unit for a hydraulic die-casting machine, provided with a device for the elimination of pressure peaks at injection

Country Status (7)

Country Link
EP (1) EP0530244B1 (OSRAM)
CN (1) CN1056643A (OSRAM)
AT (1) ATE132781T1 (OSRAM)
DE (1) DE69116361T2 (OSRAM)
ES (1) ES2080948T3 (OSRAM)
IT (1) IT1248476B (OSRAM)
WO (1) WO1991017850A1 (OSRAM)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101774005B (zh) * 2009-01-12 2012-05-30 深圳领威科技有限公司 一种油电混合的冷室压铸机压射系统
CN101774004B (zh) * 2009-01-12 2012-05-23 深圳领威科技有限公司 一种油电混合的热室压铸机压射系统
CN101530902B (zh) * 2009-04-16 2010-12-08 宁海县德科模塑有限公司 锌合金压铸模具的稳压装置
CN102451899A (zh) * 2010-10-25 2012-05-16 上海一达机械有限公司 压铸机液压系统的泵站油泵驱动装置

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2021539B2 (de) * 1970-05-02 1971-04-22 Wotan Werke Gmbh Druckgiessmaschine mit multiplikator
DE3014868A1 (de) * 1979-06-18 1981-01-22 Buehler Ag Geb Druckgiessmaschine
DE3123498C1 (de) * 1981-06-13 1983-02-03 Maschinenfabrik Müller-Weingarten AG, 7987 Weingarten Vorrichtung zum beschleunigten Aufbau und zur Regulierung des Nachdruckes an Druckgiessmaschinen

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
BURGESS HILL pages 558 - 561; PF HARRISON: 'Die Casing: The Wotan Multiject injection system ' see column 2, line 27 - column 5, line 7 *

Also Published As

Publication number Publication date
WO1991017850A1 (en) 1991-11-28
CN1056643A (zh) 1991-12-04
ES2080948T3 (es) 1996-02-16
IT1248476B (it) 1995-01-19
ATE132781T1 (de) 1996-01-15
IT9020394A0 (OSRAM) 1990-05-22
DE69116361D1 (de) 1996-02-22
EP0530244A1 (en) 1993-03-10
DE69116361T2 (de) 1996-05-30
IT9020394A1 (it) 1991-11-22

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