Classifications

• • 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
  • B29C45/40—Removing or ejecting moulded articles
  • B29C45/44—Removing or ejecting moulded articles for undercut articles
  • B29C45/4421—Removing or ejecting moulded articles for undercut articles using expansible or collapsible cores
• • 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
  • B29C45/762—Measuring, controlling or regulating the sequence of operations of an injection cycle

Definitions

• This invention relates to a method and mould for injection moulding articles in which a collapsible core part is required.
• the present invention provides a method of injection moulding an article in a mould hav ⁇ ing a collapsible core part the method including in the moulding cycle the steps of retraction of a main core, collapse of a collapsible core and retraction of the collapsible core, wherein the steps of collapse and retraction of the collapsible core are effected by hy ⁇ draulic and/or pneumatic means forming parts of the mould, said means being controlled by an electronic control circuit triggered by signals provided by the mould parts themselves when the parts reach given posi ⁇ tions.
• the invention also resides in a mould for use in an injection moulding machine, the mould having a body with a mould cavity, a main core and a collapsible core supported by the main core, the main core being re ⁇ tractable relative to the collapsible core, to permit collapse of the latter in the mould cavity, and the
• Figure 1 is a block diagram illustrating the basic control arrangement for a mould
• Figures 2A to 2G diagrammatically illustrate ⁇ tt ⁇ e- ould in various sequential stages of operation;
• Figure 3 shows in block diagrammatic form the cir ⁇ cuitry for the electronic control of Figure 1.
• the mould is intended for injection moulding con- tainers such as described in U.K. Patent Application No. 8400431.
• the container 10 has a cylindrical wall 11 and a base 12.
• a circumferential channel 13 is formed at the rim and projects radially inwardly of the cylindrical wall.
• Sockets 14 are provided at diammet- rically opposite sides of the container for receiving and mounting a yoke type handle (not shown).
• Each socket is defined by a hollow boss 15 projecting into the interior of the container, the socket being closed to the interior.
• the mould comprises a body 20 having a cavity 21, a main core member 22 and an intermediate core 23.
• the intermediate core 23 is made up of a series of fingers which extend into the cavity to form the con ⁇ tainer around the core.
• the fingers are supported by part 24 in slides, inward collapse is effected by rel ⁇ ative movement along the mould axis between the inter ⁇ mediate core 23 and the annular part 19 provided with pins 18 inclined to the mould axis.
• side cores 26 are provided which form the bosses 15 and these are mounted in the body for radial outward re-
• the mould is mounted in the moulding machine of which only the main cylinder 29 is indicated, this cycling and thereby serving to open and close the mould by acting on the main core member 22.
• the mould has first hydraulic means 30 which acts between the annular part and the core member 22.
• the first hydraulic means 30 acts in synchronism with the main cylinder 29 and holds the rest of the mould closed as the core member is retracted.
• Second hydraulic means 31 moves annular part 19 relative to the intermediate core 23 to cause radial collapse of the latter.
• Each of these hydraulic means comprises several cylinders spaced around the mould axis.
• Third hydraulic means 32 operates the side cores 26 and comprises one cylinder for each side core.
• Figure 2A shows the mould fully closed having had the plastic- material injected into the mould and allow ⁇ ed to set (cool).
• the injection and cooling time de ⁇ lays are decermined in known manner by the size of the object to be moulded and the material used and form part of the injection moulding machine control EC1.
• An electronic control panel EC2 shown in detail in Figure 3 is interfaced with the electronic control of the in ⁇ jection machine EC1 as shown in Figure 1.
• the moulding machine MC comprises means MCI, MC2 for holding the mould M as illustrated in detail in Figures 2A - G.
• the moulding machine further comprises a hydraulic ram HR and an injector I and feed hopper FH for feeding the moulding material into the mould M.
• the moulding mach ⁇ ine may for example be a GKN Windsor 330 or a Klockner Ferromatik FD 250.
• the electronic control panel EC1 for the moulding machine receives signals from the machine on line Ll and gives signals to the machine on line L2.
• the electronic control panel is basically of conventional design containing timing circuitry for timing the length of the moulding operations, e.g. in ⁇ jection and setting time and other controls related to monitoring the temperature of moulding etc. These are standard signals and are not therefore further describ ⁇ ed.
• the electronic control circuitry provides output signals on lines L3 to the electronic mould control circuit EC2 and receives signals from the circuitry on lines L4.
• the electronic control circuitry EC2 provid ⁇ es output signals on lines L5 to operate the hydraulic and air circuit control HC and to operate the protec ⁇ tion alarm PA the signals being generated as shown in greater detail in Figure 3 by input signals SI to S10 received on lines L6 from the mould of Figures 2A - G.
• the electronic control circuit EC2 comprises an input filter 40 which receives signals from the switches SI - SlO and inputs from the moulding machine control ECl on lines L3.
• the input.filter serves to isolate the further electronics from voltage surges on the input lines which may occur for example on opening cf a switch.
• the outputs of the filter 40 are fed to a decoder 42 which provides an output for a step counter 44 and also an address output for a program memory 46.
• the output of program memory 46 is fed to an output buffer/driver circuit 48 which provides outputs 01 to 08 to control the hydraulic controls Hi to H6 and the core and cavity air circuits A7 and A8 and also outputs on lines L4 to the machine control ECl.
• the hydraulic control circuit HA serves to open and close the hydraulic circuits Hla to Hlb ... H6a, H6b to perform the machine operations as hereinafter described.
• the program memory 46 may be of any suit- able form whereby a set of output signals are obtained in response to input addresses. It is possible for the program to be in the form of punched paper tape, a mat ⁇ rix, or complex relay contact arrangement. It is poss ⁇ ible to use a programmable read only memory (PROM) since this may be more readily changed but this is not necessary since the steps for any particular mould will not normally change and therefore the operational se ⁇ quence can be permanently fixed.
• PROM programmable read only memory
• the electronic control EC2 commences its operation on receipt of a signal on lines L3 indicating the com ⁇ pletion of the cooling time for the mould.
• the cooling time and temperature of moulding etc are controlled in the normal manner. They will vary for the type and size of object being moulded and do not form part of the present invention and will therefore not be des ⁇ cribed in detail.
• switches SI and S2 signal the electronic control EC2 and an output is fed to elect ⁇ ronic control ECl to enable mould opening to begin re- tracting main core member 22 as shown in Figure 2C, air is blown A7 into the mould to retain the moulding in position.
• EC2 also gives an output ' 0'3 to the hy ⁇ draulic control HC circuit H3 to operate first hydraul ⁇ ic means 30 which keeps the core 23 and annular part 19 held in position as shown in Figure 2C.
• the main core continues to retract until cylinder 30 is fully extend ⁇ ed at which point S5 signals electronic control EC2.
• Electronic control EC2 gives an output '0'5 to the hy ⁇ draulic control HC circuit (H5 operating second hydraulic means 31).
• the mould continues to open as the inter-
• mediate core is collapsed by means of the separation of part 19 containing angle pins moving away from part 24 as shown in Figure 2D.
• hydraulic means 31 When hydraulic means 31 is fully extended achieving full collapse of 23 S7 gives a signal to electronic control EC2, the output of which is fed to ECl indicating that it is safe to continue to open.
• the whole core assembly 22, 23 is then fully retracted to the fully open position of the mould as shown in Figure 2E at which time S9 is made and sends a signal to EC2.
• EC2 gives an output '0'6 to hydraulic control HC hydraulic circuit H6 of second hydraulic means 31 which re-expands the intermediate core 23 as shown in Figure 2F.
• switch S8 When the intermediate core is fully expanded switch S8 is made and the resulting sig- nal of which is fed to electronic control EC2 the out ⁇ put O'4 of which is fed to hydraulic unit HC hydraulic circuit H4 of first hydraulic means 30.
• the first hy ⁇ draulic means 30 closes up the intermediate core 23 onto the main core member 22. Air is introduced A8 to cavity 20 to eject the container as shown in Figure 2F.
• a sensor SE1, SE2, ( Figure 2G) detects the container has fallen clear of the mould and provides an input to ECl on lines Ll.
• the signal from S6 is fed to electronic control EC2.
• This signal along with signals SI, S2, S8 and the sen ⁇ sor gives an output on lines L4 from electronic control EC2 to the injection moulding machine control ECl to close the mould.
• the switch providing signal S10 is fed to elect- ronic control EC2 and is a safety switch. It is imper ⁇ ative that there is no separation between the mould body 20 and the intermediate core 23 until the core 23 has been fully collapsed. If slight separation does occur, signal S10 triggers a mould open stop via an output from EC2 to ' the electronic control ECl of the moulding machine. This is to prevent damage to the mould.

Applications Claiming Priority (2)

Publications (1)

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Family Applications (1)

Country Status (7)

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• 1984
  • 1984-04-19 GB GB848410331A patent/GB8410331D0/en active Pending
• 1985
  • 1985-04-03 ZA ZA852508A patent/ZA852508B/xx unknown
  • 1985-04-11 GB GB08509260A patent/GB2157616B/en not_active Expired
  • 1985-04-12 AU AU42117/85A patent/AU4211785A/en not_active Abandoned
  • 1985-04-12 WO PCT/GB1985/000160 patent/WO1985004836A1/en not_active Application Discontinuation
  • 1985-04-12 EP EP85901529A patent/EP0177538A1/en not_active Withdrawn
  • 1985-04-18 ES ES542399A patent/ES8700137A1/es not_active Expired
  • 1985-04-19 JP JP60084368A patent/JPS60234815A/ja active Pending

Non-Patent Citations (1)

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