FORM 2
The Patents Act 1970
(39 of 1970)
&
The Patent Rules 2003
COMPLETE SPECIFICATION
(See Section 10 and rule 13) TITLE OF THE INVENTION:
EARLY EJECTOR RETURN MECHANISM FOR
INJECTION MOULD
APPLICANT:
LARSEN & TOUBRO LIMITED
L&T House, Ballard Estate, P.O. Box No. 278,
Mumbai, 400 001, Maharashtra .
INDIA.
PREAMBLE OF THE DESCRIPTION:
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED

A) TECHNICAL FIELD
[0001] The present invention generally relates to the injection moulding tools and particularly to an ejector mechanism for ejecting the moulded plastic components. The present invention more particularly relates to an early ejector return mechanism to avoid damage to the ejector pins due to the fouling of the ejector pins with a side core.
B) BACKGROUND OF THE INVENTION
[0002] Moulding is a process of manufacturing a component by shaping pliable raw material or plastic using a rigid frame or model called a mould. The plastic raw material is heated until it melts and then forcing this melted plastic under pressure. In the injection moulding process, Thermo plastic material is melted in the injection moulding machines and then it is injected through nozzle into the mould tool. The mould tool contains the counter shape of the component and filled by the plastic material hence occupy the shape of the cavity. The thermoplastic raw materials are heated to the melting point and forced under pressure into a cold mould. A cooling circuit in the moulding tool contains water or oil flow continuously. The cooling water or oil absorbs the heat of the thermoplastic material through the harder metals and then the molten thermoplastic material is solidified. Then the mould is opened to take out the moulded component from the mould. After the completion of this process, the component is taken out or ejected from the mould tool by the ejection system provided in the tool and operated by the ejector rod in the machine. After the
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ejection is completed, it is necessary to take the mould to the closing poison for starting the next cycle. To achieve this, the return pins are provided to take back the ejector.
[0003] The injection moulding apparatus comprises a fixed half and a moving half. The fixed half is secured to the stationary platen of the moulding tool. A die cavity designed to form required component is provided in the fixed and moving halves of the mould tool. The moving half is aligned to the fixed half to form the shape of the required moulded component. The moving half or core half is secured to the moving platen of the moulding tool. The injection moulding tool also includes ejector assembly to eject the component after moulding and cooling line to set the material in core and cavity. After the ejection is completed, the return pins are provided in the injection moulding tool to take back the ejector pins to close the mould for the next cycle of operation.
[0004] In some cases, the component has slots perpendicular to the mould opening or angular to the motion of opening direction. These undercut portions of the component are formed by the side cores. The side cores are opened first to release the undercut portion of the moulded component and then the component is ejected out. During the mould closing operation, the side cores and the ejector pins are taken back simultaneously.
[0005] In some other cases, the ejector pins of the ejector assembly are placed below the side core. In such cases it is necessary to take back the side cores first and
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then the component is ejected out. During the closing operation of the mould, the ejector pins are taken back first and then closing of the side cores is implemented to avoid the fouling of the ejector pin with the side cores and to prevent the breakage of the ejector pin. Hence a special mechanism, such as an early return mechanism, is needed. The currently available early return mechanisms are complex and costly.
[0006] Hence there is a need to provide an early ejector return mechanism to avoid the damaging of a component during the ejection from the injection moulding tools and to prevent the damage to the ejector pins during the mould closing operation. Also there is a need to develop an early ejector return mechanism to release the undercuts formed by the side cores without damaging the component profile and the taken back (retreated) ejection pins during the ejection of the component in an injection moulding tool.
[0007] The above mentioned shortcomings, disadvantages and problems are addressed herein and which will be understood by reading and studying the following specification.
C) OBJECT OF THE INVENTION
[0008] These and other objects and advantages of the present invention will become readily apparent from the following detailed description taken in conjunction with the accompanying drawings.
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[0009] The primary object of the invention is to develop an early ejector return mechanism to take back/withdraw the ejector pin first during the closing of the mould to avoid damage to the ejector pins during the mould closing operation.
[0010] Another object of the invention is to develop an early ejector return mechanism to release the undercuts formed by the side cores without damaging the component profile during the ejection of the component from an injection moulding tool.
[0011] Yet another object of the invention is to develop an early ejector return mechanism and device which is cheaper than the existing early return ejection mechanisms.
D) SUMMARY OF THE INVENTION
[0012] The various embodiments of the present invention provide an early ejector return mechanism to avoid damage to a component during the ejection of the component from the injection moulding device and to avoid damage to the ejector pins during the mould closing operation. The early ejector return mechanism releases the undercuts formed by the side cores without damaging the component profile and the taken back (retreated) ejection pins during the ejection of the component in an injection moulding tool. The ejector pins are withdrawn first and the side cores are moved afterwards during the mould closing cycle.
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[0013] According to one embodiment of the present invention, an early ejector return mechanism for injection mould has a transfer plate provided in an injection mould. A latch and a return pin are provided in the transfer plate. A mating latch connector and an ejector pin are provided in the ejector plate mounted movably in the injection mould.
A dog leg cam is provided in a die housing arranged in the injection mould. A side core is provided in the punch housing arranged in the injection mould. The latch in the transfer plate is coupled to the mating latching connector in the ejector plate so that the transfer plate and the ejector plate are moved together due to the activation of the return pin to withdraw the ejector pin first and the side core is moved afterwards during the mould closing operation.
[0014] The dog leg cam is engaged with the side cores to move the side cores to the original position during the closing of the mould. The dog leg cam is moved to move the side core first during the mould opening process. The latch provided in the transfer plate is a female latching connector. The mating latching connector provided in the ejector plate is a male latching connector. The transfer plate is latched with the ejector plate through the latch and the mating latch connector to move the ejector plate along with the transfer plate to move the ejector pin during the mould opening operation.
E) BRIEF DESCRIPTION OF THE DRAWINGS
[0015] The other objects, features and advantages will occur to those skilled in the art from the following description of the preferred embodiment and the accompanying drawings in which:
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[0016] FIG. 1 illustrates a sectional view of an injection moulding device provided with an early ejection mechanism, in closed position according to one embodiment of the present invention.
[0017] FIG. 2 illustrates a sectional view of an injection moulding device provided with an early ejection mechanism according to one embodiment of the present invention, indicating the movement of the side cores and the Transfer plate during the ejection of the moulded component.
[0018] FIG. 3 illustrates a sectional view of an injection moulding device provided with an early ejection mechanism according to one embodiment of the present invention, indicating the ejection of the moulded component.
[0019] FIG. 4 illustrates a sectional view of an injection moulding device provided with an early ejection mechanism according to one embodiment of the present invention, indicating that the ejector pins are taken back and ready for moving the side cores to original position in the closing operation of the injection moulding device.
[0020] Although the specific features of the present invention are shown in some drawings and not in others. This is done for convenience only as each feature may be combined with any or all of the other features in accordance with the present invention.
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F) DETAILED DESCRIPTION OF THE INVENTION
[0021] In the following detailed description, a reference is made to the accompanying drawings that form a part hereof, and in which the specific embodiments that may be practiced is shown by way of illustration. These embodiments are described in sufficient detail to enable those skilled in the art to practice the embodiments and it is to be understood that the logical, mechanical and other changes may be made without departing from the scope of the embodiments. The following detailed description is therefore not to be taken in a limiting sense.
[0022] The various embodiments of the present invention provide an early ejector return mechanism to avoid damage to the component during ejection from the injection moulding tools. The early ejector return mechanism releases the undercuts formed by the side cores without damaging the component profile during the ejection of the component from the injection moulding tool. The early ejector return mechanism also prevents the damage to the ejector pins and the side cores during the closing of the mould.
[0023] According to one embodiment of the present invention, an early ejector return mechanism for injection mould has a transfer plate provided in an injection mould. A latch and a return pin are provided in the transfer plate. A mating latch connector and an ejector pin are provided in the ejector plate mounted movably in the injection mould.
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A dog leg cam is provided in a die housing arranged in the injection mould. A side core is provided in the punch housing arranged in the injection mould. The latch in the transfer plate is coupled to the mating latching connector in the ejector plate so that the transfer plate and the ejector plate are moved together due to the activation of the return pin to withdraw the ejector pin first and the side core is moved afterwards during the mould closing operation.
[0024] The dog leg cam is engaged with the side cores to move the side cores to the original position during the closing of the mould. The dog leg cam is moved to move the side core first during the mould opening process. The latch provided in the transfer plate is a female latching connector. The mating latching connector provided in the ejector plate is a male latching connector. The transfer plate is latched with the ejector plate through the latch and the mating latch connector to move the ejector plate along with the transfer plate to move the ejector pin during the ejection stroke or mould opening operation.
[0025] FIG. 1 illustrates a sectional view of an injection moulding device provided with an early ejection mechanism, in closed position according to one embodiment of the present invention. With respect to FIG.l, the injection moulding tool includes a base plate 1, a die housing 2, a punch housing 3, an ejector plate 4, a holder plate 5, a punch 6 and a die 7. The base plate 1 is a main part in the injection moulding tool. The die cavity is designed to get the desired shape of moulded component formed by combination of punch 6 and die 7. The punch 6, the punch housing 3 and the ejector system including the ejector plate 4 and the holder plate 5 form a moving side of the
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injection moulding tool. The die 7 and the die housing 2 along with spruce and nozzle (Feed system) form a fixed side of the injection moulding tool. In the injection moulding process, a thermo plastic material is injected into the die cavity through the nozzle at molten stage. The thermoplastic material occupies the shape of the die cavity. Further the molten material is cooled and solidified by a cooling circuit provided in the punch 6 and the die 7.
[0026] The undercuts are formed in the component during the moulding process with help of the side core 8 provided in the injection moulding tool. The movement of the side core 8 is guided by the dog leg cam 9 during the opening and closing of the mould. An ejector guide pin 10 guides the ejector pin during the closing and opening of the mould. A guide bush 11 guides the ejector plate 4 and the holder plate 5 during the closing and opening of the mould Furthermore, a transfer plate 12 is pushed by a transfer rod during the ejection of the component. A shoulder screw is provided to restrict the movement of the ejector plate 4 during the closing operation of the mould. A return pin 14 and a latch 15 are provided in the transfer plate 14. The fixed side is struck by the return pin 14 during the closing operation of the mould. The latch 15 helps in the backward movement of the moving side during the closing operation of the injection moulding tool.
[0027] FIG. 2 illustrates a sectional view of an injection moulding device provided with an early ejection mechanism according to one embodiment of the present invention, indicating the movement of moving side during the ejection of the moulded component. With respect to FIG. 2, a punch 6, a punch housing 3 and ejector system
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including a ejector plate 4 and a holder plate 5 form a moving side of the injection moulding tool. Die 7, die housing 2 along with spruce and nozzle (Feed system) form a fixed side of the injection moulding tool. In the injection moulding process, a thermo plastic material is injected into the die cavity through the nozzle at molten stage. The thermoplastic material occupies the shape of the die cavity. Further the molten material is cooled and solidified by a cooling circuit provided in the punch 6 and the die 7. While ejecting the moulded component from the injection moulding tool, the moving side core is moved backwards. The movement of the moving side core is guided by a dog leg cam 9. The dog leg cam 9 performs the forward and the rearward movement of the side core 8. The side core 8 is moved away from the cavity help of the dog leg cam 9 during opening of mould. Due to movement of the side core 8 away from the mould centre, the undercut is released from the component. The moulded component gets stuck to the moving side (punch side) following the release of the undercut. Then the moulded component is ready for ejection from the injection moulding tool. The transfer plate 12 is pushed by an ejector rod provided in the injection moulding tool during the ejection of the moulded component. The transfer plate 12 is moved forward along with return pin 14 which is fixed to the transfer plate 12.
[0028] FIG. 3 illustrates a sectional view of an injection moulding device provided with an early ejection mechanism according to one embodiment of the present invention, indicating the ejection of the moulded component. With respect to FIG. 3, the transfer plate 12 is pushed by an ejector rod provided in the injection moulding tool during the ejection of the moulded component 18 from the injection moulding
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tool. Then the transfer plate 12 is moved forward along with return pin 14 fixed to the transfer plate 12. Once the transfer plate 12 is moved forward to a definite distance, the ejector plate 4 is hit by the transfer plate 12. When the transfer plate 12 hits the ejector plate 4, the ejector plate 4 and the holder 5 moves forward along with the transfer plate 12. The forward movement of the transfer plate 12 along with ejector plate A and the holder plate 5 causes the ejector pin 16 to move above the parting surface level. The moulded component 18 is pushed outside due to the movement of the ejector pin 16 and ejected from the injection moulding tool. The side core 8 remains in the same position as illustrated in FIG. 2. A latch 15 provided in the transfer plate 12 and the ejector plate 4 get engaged with each other, when the holder plate 5 strikes the bottom face of punch housing 3. Then the moulded component 18 gets ejected from the injection moulding tool.
[0029] FIG. 4 illustrates a sectional view of an injection moulding device provided with an early ejection mechanism according to one embodiment of the present invention, indicating the closing of the injection moulding device. With respect to FIG. 4, once the moulded component is ejected from the injection moulded tool, the return pin 14 hit the fixed side and the moving side along with the return pin 14 of the injection moulding tool is moved backwards. The backward movement of the moving side along with the return pin 14 pushes the transfer plate 12 backwards. The transfer plate 12 is pushed backwards continuously along with the ejector plate 4 and holder plate 5, due to the engagement of the latch 15 between the transfer plate 12 and the ejector plate 4. During the backward movement of the transfer plate 12, the side core
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8 remains in the same position as illustrated in FIG. 2 and FIG. 3, whereas the ejector pin 16 goes back to the original position as shown in FIG. 4.
[0030] Once the ejector pin 16 comes back to the original position, the further movement of the ejector plate 4 is restricted by a shoulder screw 13. The further movement of the ejector plate 4 is restricted by shoulder screw 13 due to the forceful disengagement of the latch 15 between transfer plate 12 and ejector plate 4. Then the further movement of the ejector plate 4 is stopped and the transfer plate 12 is still moved backwards. The movement of the transfer plate 12 in backward direction causes the engagement of the dog leg cam 9 with the side core 8. Then the side core 8 is moved to close position and the moulding tool goes to closed position as shown in Fig. 1.
G) ADVANTAGES OF THE INVENTION
[0031 ] Thus the various embodiments of the present invention provide an early ejector return mechanism to avoid damage to the component during ejection in the injection moulding tools. The early ejector return mechanism releases the undercuts formed by the side cores without damaging the component profile during the ejection of the component and the taken back (retreated) ejection pins during the ejection of the component in an injection moulding tool. The early ejector return mechanism and device provided in the injection moulding tool is cheaper than the existing early ejector return mechanism /devices.
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[0032] Although the invention is described with various specific embodiments, it will be obvious for a person skilled in the art to practice the invention with modifications. However, all such modifications are deemed to be within the scope of the claims.

[0033] It is also to be understood that the following claims are intended to cover all of the generic and specific features of the present invention described herein and all the statements of the scope of the invention which as a matter of language might be said to fall there between.
Date: September 16, 2009 RAKESH PRABHU
Place: Bangalore. Patent Agent
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CLAIMS
What is claimed is
1. An early ejector return mechanism for injection mould comprising:
a transfer plate provided in an injection mould;
a latch provided in the transfer plate;
a return pin provided in the transfer plate;
an ejector plate provided in the injection mould;
a mating latch connector provided in the ejector plate;
an ejector pin provided in the ejector plate;
a die housing arranged in the injection mould;
a dog leg cam provided in the die housing;
a punch housing provided in the injection mould; and
a side core provided in the punch housing
Wherein the latch in the transfer plate is coupled to the mating latching
connector in the ejector plate so that the transfer plate and the ejector plate
are moved together due to the activation of the return pin to withdraw the
ejector pin first and the side core is moved afterwards during the mould
closing operation. 2.The mechanism according to claim 1, wherein the dog leg cam is engaged
with the side cores to move the side cores to the original position during
the closing of the mould.
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3.The mechanism according to claim 1, wherein the latch provided in the transfer plate is a female latching connector.
4.The mechanism according to claim 1, wherein the mating latching connector provided in the ejector plate is a male latching connector.
5.The mechanism according to claim 1, wherein the dog leg cam is moved to move the side core first during the mould opening process.
6,The mechanism according to claim 1, wherein the transfer plate is latched with the ejector plate through the latch and the mating latch connector to move the ejector plate along with the transfer plate to move the ejector pin during the mould opening operation.
Dated this the 16th day of September, 2009

Rakesh Prabhu,
Patent Agent, ALMT Legal,
No.2, Lavelle Road, Bangalore-560 001, INDIA
To,
The Controller of Patents,
The Patent office,
At Mumbai
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