GB2457932A - A runner system in injection impact compression moulding apparatus - Google Patents

A runner system in injection impact compression moulding apparatus Download PDF

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Publication number
GB2457932A
GB2457932A GB0803770A GB0803770A GB2457932A GB 2457932 A GB2457932 A GB 2457932A GB 0803770 A GB0803770 A GB 0803770A GB 0803770 A GB0803770 A GB 0803770A GB 2457932 A GB2457932 A GB 2457932A
Authority
GB
United Kingdom
Prior art keywords
hot runner
runner system
plastics material
injection
gate
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.)
Withdrawn
Application number
GB0803770A
Other versions
GB0803770D0 (en
Inventor
Philip Hopping
Neil Hodgson
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.)
Im Pak Technologies Ltd
Original Assignee
Im Pak Technologies Ltd
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 Im Pak Technologies Ltd filed Critical Im Pak Technologies Ltd
Priority to GB0803770A priority Critical patent/GB2457932A/en
Publication of GB0803770D0 publication Critical patent/GB0803770D0/en
Publication of GB2457932A publication Critical patent/GB2457932A/en
Withdrawn legal-status Critical Current

Links

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
    • B29C45/46—Means for plasticising or homogenising the moulding material or forcing it into the mould
    • B29C45/56—Means for plasticising or homogenising the moulding material or forcing it into the mould using mould parts movable during or after injection, e.g. injection-compression moulding
    • B29C45/561—Injection-compression moulding
    • 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
    • B29C45/18—Feeding the material into the injection moulding apparatus, i.e. feeding the non-plastified material into the injection unit
    • B29C45/1808—Feeding measured doses
    • 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
    • B29C45/26—Moulds
    • B29C45/27—Sprue channels ; Runner channels or runner nozzles
    • B29C45/2701—Details not specific to hot or cold runner channels
    • B29C45/2703—Means for controlling the runner flow, e.g. runner switches, adjustable runners or gates
    • 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
    • B29C45/26—Moulds
    • B29C45/27—Sprue channels ; Runner channels or runner nozzles
    • B29C45/2701—Details not specific to hot or cold runner channels
    • B29C45/2708—Gates
    • 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
    • B29C45/26—Moulds
    • B29C45/27—Sprue channels ; Runner channels or runner nozzles
    • B29C45/2701—Details not specific to hot or cold runner channels
    • B29C45/2708—Gates
    • B29C45/2711—Gate inserts
    • 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
    • B29C45/26—Moulds
    • B29C45/27—Sprue channels ; Runner channels or runner nozzles
    • B29C45/2725—Manifolds
    • 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
    • B29C45/26—Moulds
    • B29C45/27—Sprue channels ; Runner channels or runner nozzles
    • B29C45/278—Nozzle tips
    • 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
    • B29C45/26—Moulds
    • B29C45/27—Sprue channels ; Runner channels or runner nozzles
    • B29C45/28—Closure devices therefor
    • 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
    • B29C45/26—Moulds
    • B29C45/27—Sprue channels ; Runner channels or runner nozzles
    • B29C45/28—Closure devices therefor
    • B29C45/2806—Closure devices therefor consisting of needle valve systems
    • B29C45/281—Drive means therefor
    • 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
    • B29C45/46—Means for plasticising or homogenising the moulding material or forcing it into the mould
    • B29C45/53—Means for plasticising or homogenising the moulding material or forcing it into the mould using injection ram or piston
    • B29C45/54—Means for plasticising or homogenising the moulding material or forcing it into the mould using injection ram or piston and plasticising screw

Landscapes

  • 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)

Abstract

A hot runner system for an injection moulding machine is disclosed which comprises a block having a plurality of passages 14 each leading from a common supply port fed by an injection screw to a respective one of a plurality of gates 18 through which molten plastics material is injected into an associated one of a plurality of cavities of a mould. Each passage 14 has a branch 20 terminating in a connector 22 capable of receiving a shooting pot 24 or blanking plug 34. When an injection process requires plastics material to be metered to each cavity of the mould individually, the shooting pot 24 is screwed to the connector 22. Otherwise, the connector 11 receives the blanking plug 34.

Description

--
INJECTION IMPACT COMPRESSION MOULDING APPARATUS
Field of the invention
The present invention relates to an apparatus for injection impact compression moulding.
Background of the invention
In conventional injection moulding, a molten plastics material is injected into a fully close mould until the mould is filled to its maximum capacity. If a multi-cavity mould is used, the plastics material from a single injection screw can be supplied in parallel to all the mould cavities.
As soon as a cavity is filled to its maximum capacity, the flow from the injection screw is automatically diverted by the back pressure to another cavity until all the cavities are full. Consequently, no special steps need to be taken to ensure that the correct dose is metered to each individual cavity.
In injection compression moulding, a plastics material is injected to fill fully a cavity while it is closed, but bounding a volume greater than that of the article to be moulded. As the plastics material cools, it tends to shrink and, to compensate for this, a force is applied to reduce the volume of the cavity so as to compress the plastics material as at is cooling. In this way, it is possible to form articles, such as optical lenses, where the shape and surface finish are of critncal importance. Because, once again, the plastics material is injected to occupy each mould cavity fully, no special steps are needed to meter the plastics material to individual cavities when a multi-cavity mould is used. Th
Injection impact compression moulding is used to form article having wall sections with a large length to thickness ratio. Because of these thin walled sections, the pressure available from an injection screw cannot be used to fill the mould cavity because the molten plastics material would solidify before it has reached the ends of the thin s walled sections. Instead, as is the case in injection compression moulding, the plastics material is injected into the mould cavity while its volume is greater than that of the article tc be formed. However, in contrast to injection compression moulding, the plastics material only partially fills the mould cavity and does not enter the thin walled sections. The mould is subsequently closed rapidly to force the injected plastics material to flow into the remaining thin wailed sections of the mould cavity. For example, if forming a cup, the initially plastics material lies only in is the base of the cup and the closing of the mould forces the plastics material to flow along the conical wall of the cup until it reaches the upper rim. The impact compression process is analogous to the forging of objects made of metal.
The important difference to note in the case of injection impact compression moulding is that the plastics material does not fill the cavity at the end of the injection phase. For this reason, when using a multi-cavity mould it has hitherto proved essential to meter the doses of plastics material individually to the different cavities.
Such metering has been achieved by the use of piston-cylinder units, termed shooting pots, in the hot runner system. Several shooting pots, each associated with a respective one of the cavities, are filled in parallel to their maximum capacity by the injection screw. The shooting pots are then isolated by valves from the injection screw and each then supplies the metered dose of the plastics material that it contains to its associated cavity.
The hot runner system is a component that forms part of the injection moulding press that receives the mould. The press comprises hoppers that feed granular plastics to the injection screw. The screw is heated and rotated to supply molten plastics material under pressure to the hot runner system. The latter distributes the molten plastics material to gates through which it is injected into the individual cavities of the mould (or moulds) The stationary part of the mould, usually the female part, is mounted on the hot runner system. The other ha'f, 0 usually a male core, is mounted on a platen and is movable towards and away from the stationary part by the mechanism of the press, which may be hydraulic or electric and which may act either directly on the movable platen or by way of a system of toggle levers that pass through an over-centre :5 position to lock the mould parts tightly together. The present invention is applicable to all presses regardless of the type of mechanism used to press the mould parts against one another.
It will be clear from the above description that the hot runner system needs to include shooting pots if the press is to be used for injection impact compression moulding and such shooting pots need not be present when the press is used for conventional injection moulding or injection compression moulding. Furthermore, when used for injection impact compression moulding, the size of the shooting pots needs to be matched to the article being moulded. For these reasons, it has hitherto been necessary to replace the entire hot runner system when switching between different moulds.
Object of the invention The present invention seeks to mitigate the above disadvantage and to enable a hot runner system to be modified in a simple manner so that is may be used both in injection moulding processes that require shooting pots and in processes that to not require shooting pots.
Summary of the invention
According to a first aspect of the present invention, there is provided a hot runner system for an injection moulding machine comprising a block having a plurality of passages each leading from a common supply port fed by an ro injection screw to a respective one of a plurality of gates through which molten plastics material is injected into an associated one of a plurality of cavities, characterised each passage has a branch terminating in a connector capable of selectively receiving either one of a blanking plug and a is shooting pot.
In a preferred embodiment of the first aspect of the invention, the block of the hot runner has screw threaded connectors that communicate with the passages carrying molten plastics material to the injection gates associated with the individual cavities. The connectors may either be blanked off by screwing in a suitable blanking plug, or they may each receive a respective shooting pot of a size appropriate tc the article being moulded. is
In accordance with a second aspect of the invention, there is provided a gate assembly having a body for mounting on the block of a hot runner system to communicate with a passage in the hot runner system supplying molten plastics material to a mould cavity associated with the gate assembly, wherein the body comprises a gate, a valve tor opening and closing the gate and a conduit within the body leading from the passage in the hot runner system to the gate, wherein the conduit within the body of the gate assembly has a branch terminating in a connector capable selectively of receiving a blanking plug and a shooting pot.
In the second aspect of the invention, it is recognised that the gate assemblies may be formed separately from the block of the hot runner system. In such a construction, the connector for receiving a shooting pot or a blanking plug can form part of the gate assembly rather than of the block of the hot runner system.
Once again the connectors may preferably be screw threaded.
Brief description of the drawings
The invention will now be described further, by way of example, with reference to the accompanying drawings, in which Figure 1 shows a gate assembly embodying the invention when connected to a shooting pot, and Figure 2 shows the gate assembly of Figure 1 with the shooting pot removed and with a blanking plug in the connector for the shooting pot.
Detailed description of the preferred embodiment(s) Figure 1 shows a gate assembly 10 comprising a body 12 have a conduit 14 that leads from a supply port 16 to an injection gate 18, The gate 18 controlled by a valve 20 which is operated by a pneumatic of hydraulic jack comprising a piston 2i moi.inted in a chamber 23 formed in the body 12.
The illustrated gate assembly 10 is intended to be mounted on the block of a hot runner system with the supply port 16 in communication with a passage in the hot runner system that leads to an injection screw. It is however alternatively possible for the body 12 to form an integral part of the hot runner system.
The conduit 14 within the body 12 has a branch 20 that terminates in a screw connector 22. In Figure 1, a shooting pot 24 is screwed into the connector 22. The shooting pot 24 comprises a cylinder 26, a piston 28 and a stop 30, which may adjustable, to limit the stroke of the piston 28 and determine the maximum volume of the variable volume working chamber 32 of the shooting pot.
In Figure 2, the same gate assembly 10 is shown with the shooting pot 24 replaced by a blanking plug 34. Figure 2 also shows the gate valve in its closed position, whereas it is shown in an open position in Figure 1.
When used in an injection process that does not require is the dose of plastics material to each mould cavity to be metered, the gate assembly 10 has its connector 22 blanked off as shown in Figure 2. After the mould has been closed, the gate valve 20 is retracted by the piston 21 to allow plastics material to be injected by the injection screw via the conduit 14 until the cavity is filled to its maximum capacity. The valve 2C is then move to closed the gate 18, to allow the mould to be opened and the moulded article to be ejected from the mould in readiness for the next cycle.
When use in an injection proceed that does require the plastics material to be metered to each cavity individually, a shooting pot 24 is mounted in the connector 22 as shown in Figure 1. At the commencement of a cycle, the piston 28 is in its iowermcst position and the gate 18 is closed.
Plastics material is in:ected from the injection screw into the conduit 14 via a passage in the hot runner system.
During this time, the piston 28 of the shooting pot is free to move and the working chamber of the shooting pot is filled to its maximum capacity, i.e. until the piston 28 s reaches the stop 30. At this point, the gate 18 is opened by retraction of the valve 20 and actuator (not shown) applied a force to the piston 28 minimise the volume of the working chamber 32. In this way, a precise dose of plastics material is metered to the cavity corresponding to the displacement of the piston 28 of the shooting pot. The gate 18 may now be closed in readiness for the next operating cycle.
It can be seen from the above that the invention enables the same hot runner system to be used in different injection processes and that the only adapration required is to attach a shooting pot of the appropriate dimensions or a blanking plug, depending on whether or not the injected dose of plastics material needs to be metered.

Claims (5)

  1. CLAIMS1. A hot runner system for an injection moulding machine comprising a block having a plurality of passages each leading from a common supply port fed by an injection screw to a respective one of a plurality of gates through which molten plastics material is injected into an associated one of a plurality of cavities, characterised each passage has a branch terminating in a connector capable of selectively receiving either one of a blanking plug and a shooting pot.
  2. 2. A hot runner system as claimed in claim 1, wherein the block of the hot runner has screw threaded connectors s that communicate with the passages carrying molten plastics material to the injection gates associated with the individual cavities.
  3. 3. A gate assembly having a body for mounting on the block of a hot runner system to communicate with a passage in the hot runner system supplying molten plastics material to a mould cavity associated with the gate assembly, wherein the body comprises a gate, a valve for opening and closing the gate and a conduit within the body leading from the passage in the hot runner system to the gate, wherein the conduit within the body of the gate assembly has a branch terminating in a connector capable selectively of receiving a blanking plug and a shooting pot.
  4. 4. A gate assembly as claimed in claim 3, wherein the connector is a screw threaded connector.
  5. 5. A gate assembly constructed and adapted to operate substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.
GB0803770A 2008-02-29 2008-02-29 A runner system in injection impact compression moulding apparatus Withdrawn GB2457932A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB0803770A GB2457932A (en) 2008-02-29 2008-02-29 A runner system in injection impact compression moulding apparatus

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB0803770A GB2457932A (en) 2008-02-29 2008-02-29 A runner system in injection impact compression moulding apparatus

Publications (2)

Publication Number Publication Date
GB0803770D0 GB0803770D0 (en) 2008-04-09
GB2457932A true GB2457932A (en) 2009-09-02

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Family Applications (1)

Application Number Title Priority Date Filing Date
GB0803770A Withdrawn GB2457932A (en) 2008-02-29 2008-02-29 A runner system in injection impact compression moulding apparatus

Country Status (1)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5260012A (en) * 1990-02-16 1993-11-09 Husky Injection Molding Systems Ltd. Molding plastic articles
JPH09207177A (en) * 1996-02-05 1997-08-12 Sumitomo Heavy Ind Ltd Mold apparatus and injection molding method
DE102004009320A1 (en) * 2003-02-26 2004-11-18 Mold-Masters Ltd., Georgetown Hot runner system for controlling cross-sectional asymmetric condition of laminar flowing material comprises flow rotator having bending path for orienting outlet relative to inlet to divide equally the condition between two downstreams

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5260012A (en) * 1990-02-16 1993-11-09 Husky Injection Molding Systems Ltd. Molding plastic articles
JPH09207177A (en) * 1996-02-05 1997-08-12 Sumitomo Heavy Ind Ltd Mold apparatus and injection molding method
DE102004009320A1 (en) * 2003-02-26 2004-11-18 Mold-Masters Ltd., Georgetown Hot runner system for controlling cross-sectional asymmetric condition of laminar flowing material comprises flow rotator having bending path for orienting outlet relative to inlet to divide equally the condition between two downstreams

Also Published As

Publication number Publication date
GB0803770D0 (en) 2008-04-09

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WAP Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1)