GB2061804A - Method and hydraulic circuit arrangement for injection moulding - Google Patents

Method and hydraulic circuit arrangement for injection moulding Download PDF

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Publication number
GB2061804A
GB2061804A GB8036176A GB8036176A GB2061804A GB 2061804 A GB2061804 A GB 2061804A GB 8036176 A GB8036176 A GB 8036176A GB 8036176 A GB8036176 A GB 8036176A GB 2061804 A GB2061804 A GB 2061804A
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GB
United Kingdom
Prior art keywords
closure
locking
pressure
cylinder
opening
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.)
Granted
Application number
GB8036176A
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GB2061804B (en
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.)
Umformtechnik Herbert Warnke VEB
Original Assignee
Umformtechnik Herbert Warnke VEB
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 Umformtechnik Herbert Warnke VEB filed Critical Umformtechnik Herbert Warnke VEB
Publication of GB2061804A publication Critical patent/GB2061804A/en
Application granted granted Critical
Publication of GB2061804B publication Critical patent/GB2061804B/en
Expired legal-status Critical Current

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Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29CSHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C45/00Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
    • B29C45/17Component parts, details or accessories; Auxiliary operations
    • B29C45/64Mould opening, closing or clamping devices
    • B29C45/67Mould opening, closing or clamping devices hydraulic
    • B29C45/6707Mould opening, closing or clamping devices hydraulic without relative movement between the piston and the cylinder of the clamping device during the mould opening or closing movement

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Mechanical Engineering (AREA)
  • Moulds For Moulding Plastics Or The Like (AREA)
  • Injection Moulding Of Plastics Or The Like (AREA)
  • Crystals, And After-Treatments Of Crystals (AREA)

Abstract

In a method of closing and locking mould halves of an injection moulding machine carried by platens, one platen 18 is movable and the other platen 30 is fixed, and platen 18 is moved into the closure position by long-stroke low-pressure traverse cylinders 17. The mould closure force is applied by short- stroke high-pressure cylinders 12 arranged in the platen 30 at one end of force transmitting columns 16 which pass through the movable platen 18. For locking the movable platen 18 to the columns 16, hydraulic locking cylinders 27 are pressurised to actuate locking jaws 33. The actuation is initiated by a cam 21 co-operating with a switch 20 which operates a directional valve 22 in a hydraulic circuit having a pressure source 2. Each cylinder 27 has a piston rod 42 which carries a cam 41 co-operating with a switch 40 which controls the flow of pressure fluid to chamber 14 of the cylinder 12 for closing and clamping the mould. For the opening of the mould the cylinders 12 and 27 are actuated simultaneously. <IMAGE>

Description

SPECIFICATION Method and hydraulic circuit arrangement for injection mouding This invention relates to a method and a hydraulic circuit arrangement for actuating a mould closing arrangement, having a movable and a fixed mould mounting platen, of plastics injection moulding machines, in which the mould mounting platens are locked to one another before the mould closure and clamping force is applied. The invention is applicable in a similar manner to metal pressure casting machines.
Injection moulding machines are known in which the movement of the movable mould mounting platen is effected by separately disposed, relatively long-stroke working cylinders, locking being effected simultaneously by locking elements mounted for constrained movement, with a superimposition of rotational and translational movement. Unlocking is effected synchronously with the opening stroke. A locking unit of the kind specified is known from German Democratic Republic Patent 1 32944.
The mould closing arrangement comprises a fixed and a movable mould mounting platen and also a supporting plate for force transmitting columns. After locking, the columns effect the function of a closure piston, at the same time acting as locking elements. They are moved both axially and rotationally by means of a curved sector dog means. The columns are rotationally mounted in the supporting platen and can be locked axially by securing elements. Disposed fixed in the movable mould mounting platen are rings which have inner dogs. Bushes fixed to the columns are constructed in the form of a double collar on the mould side, the collar being formed with recesses through which the inner dogs extend during the closure operation.By the constrained guidance during travel by a cam guideway system, the columns are moved axially by the length of the closure stroke and rotationally by the angle of rotation, in order to lock the outer dogs formed by the recesses in the collar to the inner dogs in the rings.
Then the short-stroke closure cylinders can be brought in without interrupting the travel.
That locking system has the following disadvantages. The cam guidepath systems for the bushes and columns are liable to wear. Moreover, due to the relatively large mass of the four columns and the resulting high kinematic input, the locking system disclosed in German Democratic Republic Patent 132944 is liable to get jammed.
Another very disadvantageous aspect is the relatively large stroke of the large-area closure piston which is due to the characteristics of the cam path control system and is required only for the locking operation. The fact is that for this purpose a very large amount of hydraulic fluid in the closure cylinder must be displaced and sucked back, so that the final part of the stroke of the mould mounting platen is considerably decelerated. Moreover, for this reason relatively long guide and sealing surfaces are required.
It is an object of the invention to provide a closure unit with wear-resistant locking elements which ensure that the locking time is not disadvantageous to the total cycle time of the injection moulding machine.
The problem which the invention aims at solving is to provide a method enabling the closure and locking operation and also the unlocking and opening operation to be carried out continuously in one working cycle, the passive stroke of the closure piston which is required to initiate the locking operation being shortened, the mechanical constrained guidance of the locking elements being eleminated, a hydraulic circuit arrangement being provided for carrying out the method.
Accordingly, the present invention consists in a method of closing and locking mould halves of injection moulding machines which halves are carried by mould mounting platens of which one is movable and the other fixed, wherein the movable platen is moved into the closure position in relation to the fixed platen by long-stroke low pressure traverse cylinders, locking is effected simultaneously with the traverse stroke, the closure and opening force is applied by short-stroke high pressure closure and opening cylinders arranged at one end of force transmitting columns which pass through the movable platen, and after the cooling of the moulding, unlocking is effected simultaneously with the opening stroke, characterised in that during the traverse stroke into the closure position a hydraulic locking cylinder, having a piston with an extended piston rod, is pressurised by a cam disposed on each column actuating a respective switch before the closure position is reached, said switch switching a directional valve of a hydraulic circuit, after the locking stroke has been effected, the closure force is applied by a further cam attached to the extended piston rod of said locking cylinder actuating a further switch which switches two further directional valves, so that the pressure chamber of the closure and opening cylinder is pressurised, and that for the removal of the moulding the closure and opening cylinder and the locking cylinder are actuated simultaneously by the pressure chambers of the closure and opening cylinder and of the locking cylinder being pressurised.
The hydraulic circuit arrangement for carrying out the method comprises a hydraulic circuit which includes downstream of a pressure flow generator two hydraulic branch lines, of which one is connected via a nonreturn valve to a pressure accumulator, down stream of which a pressure-limiting valve connected in parallel is disposed, a connection to the locking cylinder being made via a directional valve which is operated electrically via a switch which is actuated by a cam disposed on the columns, and the second hydraulic branch line is connected via a combination of two further directional valves to the closure or opening cylinder, a non-return valve being disposed in the return lines of the further directional valves which are actuated via a switch which operates in dependence on travel in relation to the locking device.
In order that the invention may be more readily understood, reference is made to the accompanying drawings which illustrate diagrammatically and by way of example an embodiment thereof, and in which:~ Figure 1 is a partial sectioned view of the most important operating elements of a mould closing arrangement with columns mounted in an additional supporting platen, and Figure 2 shows the hydraulic circuit arrangement for carrying out the method according to the invention.
Fig. 1 shows the application of the method according to the invention in an embodiment having force transmitting columns 16 supported in an additional supporting platen 31.
The associated hydraulic circuit diagram is shown in Fig. 2. A movable mould mounting platen 18 is disposed on a base frame (not shown in detail) with provision for displacement towards and away from a fixed mould mounting platen 30 by means of traverse cylinders 1 7.
Each column 1 6 extends into the fixed mounting platen 30 where it co-operates with a double-acting closure and opening piston 15 of a closure and opening cylinder 12 to form an operational unit. The necessary overall mould part installation spacing is adjusted via column nuts 19. Locking cylinders 27 with pistons 35 are disposed directly on the movable mould mounting platen 18. Locking jaws 33 arranged in pairs are actuated eccentrically in known manner by pistons 35 in the radial direction in relation to the column 1 6, although this is not shown in detail. As a result the columns 1 6 are locked to the movable mould mounting platen 18. The pressure chambers 26; 29 of the locking cylinder 27 can be connected selectively to the lines 25; 38.Disposed on each column 16 is a cam 21 which in dependence on travel actuates a switch 20 which initiates the switching impulses for locking. Disposed directly on the locking cylinder 27 is a lug 43 to which a switch 40 is attached. Extended piston rod 42 of the locking piston 35 has at its lower end a cam 41. After the locking stroke has been effected, the cam 41 actuates the switch 40, thus initiating the signal for the build-up of closure force.
The operation of the method according to the invention and of the associated hydraulic circuit will now be briefly described.
In the opening position for the removal of the moulding the movable mould mounting platen 1 8 and the fixed mould mounting platen 30 are at the greatest possible distance apart.
In this inoperative position of the mould closing arrangement a pressure flow generator 2 delivers pressurised liquid from a reservoir 1 to z line 3, which is connected to a line 5 in the operative position I of a directional valve 4. The pressurised liquid passes through the# line 5 via a non-return valve 6 to the reservoir 1. The damming pressure building up at the non-return valve 6 is transmitted via line 7 and the directional valve 4 (operative position I) to line 8, and via the operative position I of a further directional valve 9 to the lines 10, 11. As a result the closure and opening cylinder 1 2 in both pressure chambers 1 3, 14 is pressurised by this damming pressure.Due to the circuit produced at the directional valve 9 for a working cylinder with one-sided piston rod (operational position I), the closure and opening piston 1 5 is retained in its left-hand end position (as viewed in Fig. 2) with a low, but constant force. The pressure liquid displaced in the closure and opening cylinder 12 by the closure and opening piston 1 5 is displaced through line 10 via the directional valve 9 (operational position I) and line 11 to pressure chamber 1 3. The excess pressure liquid passes via line 8 and directional valve 4 (operational position 1), the line 7 and the non-return valve 6 to the reservoir 1.At the same time the pressure flow generator 2 is connected to the pressure chamber 29 of the locking cylinder 27 via line 3, non-return valve 23, lines 24, 38 and directional valve 22, which is in the operational position I. The locking piston 35 is therefore retained in its required starting position by a pressure head.
For a further injection moulding operation the traverse cylinder 1 7 is pressurised, so that the movable mould mounting platen 18 is moved in the direction of the fixed mould mounting platen 30. The inner surfaces of platen attachments 34 abut the column nuts 1 9. Then the kinetic energy by which the movable platen 18 is moved transmits a force via the column nuts 1 9 to the columns 16 cooperating with the closure and opening pistons 1 5 to form an operating unit. Immediately before the closure position is reached, the switch 20 operable in dependence on travel is actuated via the cam 21 attached to the columns 1 6, so that an electric signal for locking is immediately produced. This signal switches the directional valve 22 into operational position ll. The pressure flow generator 2 then delivers via the line 3 via the nonreturn valve 23 to the line 24 and via the directional valve 22 (operational position II) to the line 25, which is connected to the pres sure chamber 26 of the locking cylinder 27.
The locking piston 35 then actuates the locking jaws 33 disposed in pairs, although this will not be described in detail in this connection. The movable mould mounting platen 18 is therefore locked into the closure position with the columns 16 by positive connection in one working cycle synchronously with the traverse stroke.
Locking is effected very quickly, since the line 24 is connected to a pressure accumulator 36 whose pressure is transmitted via the directional valve 22 (operational position II) and the lines 24, 25 to the pressure chamber of the locking cylinder 27. The maximum operating pressure of the installation is determined by a pressure-limiting valve 37.
After the locking operation, a continuous transition to the build-up of closure force takes place immediately. This is ensured by the cam bar 41 attached to the extended piston rod 42 actuating the switch 40 immediately after the locking stroke has been effected. The switch 40 is connected by switching technique to the directional valves 4, 9, which are then switched into the operational position II.
The pressure flow generator 2 then delivers pressurised liquid via the line 3, directional valve 4, line 8 and the directional valve 9 and line 10 to the closure and opening cylinder 12, as a result of which the closure pressure is generated in the pressure chamber 14 of the closure and opening cylinder 12. The pressurised liquid displaced from the pressure chamber 13 flows away into the reservoir 1 via line 11, directional valve 9, lines 5, 7 and non-return valve 6.
After the injection moulding operation has been completed and the moulding cooled, the directional valve 9 is switched into the operational position I. The pressure flow generator 2 delivers pressurised liquid via the combination of directional valves 4, 9 and lines 3, 8 to the line 10, 11, the directional valve 4 being in the operational position ll. The circuit produced at the directional valve 9 for a working cylinder with one-sided piston rod displaces the closure and opening piston 15 into its left-hand end position. Simultaneously with the opening movement of the closure and opening piston 15, unlocking is effected.
The directional valve 22 is in the operational position I. The line 24, to which the accumulator 36 is connected, is connected via the directional valve 22 and the line 38 to the pressure chamber 29 of the locking cylinder 27. The volume of pressurised liquid required for the unlocking operation is made available by the accumulator 36. The locking jaws 33 disposed in pairs are actuated by the pressurised chambers 29 via the pistons 35, so that unlocking is effected without idle times in one operating cycle with the opening stroke. During the cycle times the accumulator 36 is charged when during the operating cycle "build-up of closure force" and "mould opening" the pressure flow generator 2 operates against the adjusting pressure of the pressurelimiting valve 37.
For the sake of completeness it should be pointed out that in each case the description relates to an opening and closure cylinder 12 and a locking cylinder 27. In accordance with the construction and operation of this method according to the invention and of the hydraulic circuit in injection moulding machines of the given known construction, four opening and closure cylinders 12 and locking cylinders 27 are needed in each case, corresponding to the number of columns 16. These hydraulic cylinder/piston units are interconnected by parallel circuits, so that the individual cylinder/piston units are enabled to operate synchronously and reliably.

Claims (4)

1. A method of closing and locking mould halves of injection moulding machines which halves are carried by mould mounting platens of which one is movable and the other fixed, wherein the movable platen is moved into the closure position in relation to the fixed platen by long-stroke low pressure traverse cylinders, locking is effected simultaneously with the traverse stroke, the closure and opening force is applied by short-stroke high pressure closure and opening cylinders arranged at one end of force transmitting columns which pas through the movable platen, and after the cooling of the moulding, unlocking is effected simultaneously with the opening stroke, characterised in that during the traverse stroke into the closure position a hydraulic locking cylinder, having a piston with an extended piston rod, is pressurised by a cam disposed on each column actuating a respective switch before the closure position is reached, said switch switching a directional valve of a hydraulic circuit, after the locking stroke has been effected, the closure force is applied by a further cam attached to the extended piston rod of said locking cylinder actuating a further switch which switches two further directional valves, so that the pressure chamber of the closure and opening cylinder is pressurised, and that for the removal of the moulding the closure and opening cylinder and the locking cylinder are actuated simultaneously by the pressure chambers of the closure and opening cylinder and of the locking cylinder being pressurised.
2. A method of closing and locking mould halves of injection moulding machines, substantially as herein described with reference to the accompanying drawings.
3. A hydraulic circuit arrangement for carrying out the method claimed in claim 1, wherein a hydraulic circuit downstream of a pressure flow generator comprises two hydraulic branch lines, one of which is con nected via a non-return valve to a pressure accumulator, downstream of which a pressure-limiting valve connected in parallel is disposed, and a connection to the locking cylinder is made via a directional valve which is electrically operated via a switch actuated by a cam disposed on the columns, and the second hydraulic branch line is connected via a combination of two further directional valves to the closure or opening cylinder, a nonreturn valve being disposed in return lines of the directional valves which are actuated via a further switch.
4. A hydraulic circuit arrangement, substantially as herein described with reference to and as shown in Fig. 2 of the accompanying drawings.
GB8036176A 1979-11-13 1980-11-11 Method and hydraulic circuit arrangement for injection moulding Expired GB2061804B (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DD79216850A DD146405A1 (en) 1979-11-13 1979-11-13 METHOD AND HYDRAULIC CIRCUIT ARRANGEMENT FOR INJECTION MOLDING

Publications (2)

Publication Number Publication Date
GB2061804A true GB2061804A (en) 1981-05-20
GB2061804B GB2061804B (en) 1983-10-05

Family

ID=5521025

Family Applications (1)

Application Number Title Priority Date Filing Date
GB8036176A Expired GB2061804B (en) 1979-11-13 1980-11-11 Method and hydraulic circuit arrangement for injection moulding

Country Status (11)

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AT (1) AT378499B (en)
BG (1) BG37255A1 (en)
CS (1) CS268754B1 (en)
DD (1) DD146405A1 (en)
DE (1) DE3031641A1 (en)
FR (1) FR2469267B1 (en)
GB (1) GB2061804B (en)
IT (1) IT1146994B (en)
SE (1) SE433923B (en)
SU (1) SU1152706A1 (en)
YU (1) YU271480A (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1369218A1 (en) * 2002-06-06 2003-12-10 Negri Bossi S.P.A. A mould closing and clamping system for an injection moulding machine
CN111186106A (en) * 2018-11-14 2020-05-22 恩格尔奥地利有限公司 Molding machine and mold clamping unit thereof
CN113165241A (en) * 2018-10-05 2021-07-23 阿博格有限公司 Clamping unit for an injection molding machine and method for locking a force transmission element

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
IT1219271B (en) * 1988-05-06 1990-05-03 Adelio Grasselli IMPROVEMENT RELATING TO LARGE PRESSES FOR INJECTION MOLDING OF POLYESTER AND ELASTOMER THERMOPLASTIC MATERIALS
US5192557A (en) * 1990-07-27 1993-03-09 Nissei Jushi Kogyo K.K. Clamping apparatus for molding machine
DE4431260C1 (en) * 1994-09-02 1995-10-26 Hemscheidt Maschtech Schwerin Hydraulic circuit for injection moulding machine
AT521266B1 (en) * 2018-10-09 2019-12-15 Engel Austria Gmbh Closing unit for a molding machine

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DD79378A (en) *
FR1065384A (en) * 1952-07-22 1954-05-24 Improvements made to presses, especially those with hydraulically controlled pistons
FR1141429A (en) * 1955-05-12 1957-09-02 Italiana Macchine Stampaggio A Advanced, high-power machine for injection molding of thermoplastic materials
US3540081A (en) * 1967-08-21 1970-11-17 Us Industries Inc Vertical injection molding machine
CH521837A (en) * 1970-03-20 1972-04-30 Buehler Ag Geb Closing, locking and pre-tensioning device for casting molds
US3669599A (en) * 1970-12-08 1972-06-13 Nat Automatic Tool Co Hydromechanical clamp
US3833333A (en) * 1972-11-06 1974-09-03 G Britten Press construction
FR2251393A1 (en) * 1973-11-21 1975-06-13 Leguen Et Hemidy Injection moulding machine with only two robust platens - using the bar tension for the locking force
US4029457A (en) * 1974-06-17 1977-06-14 Toshiba Kikai Kabushiki Kaisha Molding machine
US3940930A (en) * 1975-01-20 1976-03-02 Package Machinery Company Hydraulic system for injection molding machine
DD132944A1 (en) * 1977-05-10 1978-11-22 Klaus Fueller TOOL CLOSURE AND LOCKING UNIT IN PARTICULAR FOR INJECTION MOLDING MACHINES
DE2812301A1 (en) * 1977-05-10 1978-11-23 Plast Elastverarbeitungsmasch TOOL LOCKING AND LOCKING UNIT, IN PARTICULAR FOR INJECTION MOLDING MACHINES

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1369218A1 (en) * 2002-06-06 2003-12-10 Negri Bossi S.P.A. A mould closing and clamping system for an injection moulding machine
CN113165241A (en) * 2018-10-05 2021-07-23 阿博格有限公司 Clamping unit for an injection molding machine and method for locking a force transmission element
CN113165241B (en) * 2018-10-05 2023-03-28 阿博格有限公司 Clamping unit for an injection molding machine and method for locking a force transmission element
CN111186106A (en) * 2018-11-14 2020-05-22 恩格尔奥地利有限公司 Molding machine and mold clamping unit thereof
CN111186106B (en) * 2018-11-14 2022-02-08 恩格尔奥地利有限公司 Molding machine and mold clamping unit thereof

Also Published As

Publication number Publication date
SE433923B (en) 1984-06-25
AT378499B (en) 1985-08-12
SE8007954L (en) 1981-05-14
DD146405A1 (en) 1981-02-11
IT1146994B (en) 1986-11-19
GB2061804B (en) 1983-10-05
FR2469267B1 (en) 1986-11-14
YU271480A (en) 1984-06-30
IT8050121A0 (en) 1980-11-11
CS268754B1 (en) 1990-04-11
FR2469267A1 (en) 1981-05-22
DE3031641A1 (en) 1981-05-21
SU1152706A1 (en) 1985-04-30
ATA438880A (en) 1985-01-15
BG37255A1 (en) 1985-05-15

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PCNP Patent ceased through non-payment of renewal fee