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:


A SELF ACTUATED MECHANISM TO EJECT PARTS WITH SINGLE OR MULTIPLE START INTERNAL THREADS
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 molding of plastic objects and particularly relates to an ejection mechanism for moulded components with internal threads. The present invention more particularly relates to a self actuated mechanism to eject parts with multiple start internal threads.
B) BACKGROUND OF THE INVENTION
[0002] Thermoplastic moulded articles are used extensively in everyday life. Thermoplastics are linear or branched polymeric materials which melt when heated and resolidify when cooled. Mould apparatus can be designed to any required shape and used repeatedly to manufacture copious amounts of moulded articles. Various moulding methods are used to manufacture articles using moulds of required shape and size. Injection moulding is used to manufacture articles of different shapes and sizes ranging from small components to automobile body panels.
[0003] In injection moulding process thermoplastic raw materials are heated to melting point and forced under pressure into cold mould. Injecton pressure forces the melted liquid into the mould to cool and solidify. Injection molding apparatus comprises of a fixed half and a moving half. The fixed half is secured to the stationary platen of the apparatus. The moving half or core half is secured to the moving platen of the apparatus.

It also includes ejector assembly to eject the component after molding and cooling line to

set the material in core and cavity.
[0004] The cavity designed to form the required article is provided in the fixed and moving halves of the apparatus. The moving half is aligned to the fixed half to form the shape of the required moulded component. The melted plastic is injected through feed system arrangement of the apparatus into the cavity. The melted plastic cools and solidifies to form the required moulded component.
[0005] The undercuts are released using additional designs in the apparatus. The mould may be opened in multiple layers. Additional release surfaces may be provided to slide and release external undercuts using various actuation mechanisms including mechanical, hydraulic and pneumatic methods.
[0006] Internal undercuts may be released using various methods including collapsible cores or internal slides. Double ejection method may be used to activate ejector plates sequentially to relieve the surface around the undercut to expand and eject the moulded components. However the current methods to eject internal undercuts are expensive and complex. The additional ejection components to relieve the undercuts require various associated mechanisms to actuate the components. The maintenance of the components is difficult. Hence there is a need to provide a simple, efficient and cost effective method to relieve internal undercuts for ejection of moulded articles.

0007] In some product design, component feature is designed in such a manner that it is

not in the direction of the mould opening, called as under cuts. In such cases, different
mechanisms such as angle pin mechanism, dog leg cam mechanism, hydraulic cylinder,
sprung core, angular core etc are used to remove the under cuts in mould opening
direction. In case of components with internal double start threads, the moulded
components can be ejected by using unscrewing mechanism and collapsible core
construction method.
[0008] In unscrewing mechanism the core insert is moved upwards and down words with rotational movement to release the component. In this case the component is remained stationary. This leads to a complicated gear train mechanisms to give linear and rotational movement to the core insert. In unscrewing mechanism a gear train is used which rotates and translates the threaded core, this facilitates the removal of threaded component.
[0009] The conventional methods available for ejecting the moulded components are not suitable for ejecting the components with double start internal threads. Hence there is a need to provide a method to eject the threaded component without using conventional approaches of unscrewing or collapsible core. Also there is a need to develop an arrangement to release the undercut or threads without damaging the component profile.
C) OBJECTS OF THE INVENTION
[0010] The primary object of the present invention is to provide a self actuated mechanism to eject and relieve the moulded parts with multiple start internal threads.

[0011] Yet another object of the present invention is to provide a self actuated mechanism to eject the moulded component cam by using the helical threaded profile of the cam.
[0012] Yet another object of the present invention is to provide a self actuated mechanism to release the undercut (i.e. threads) without damaging the component profile.
[0013] 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.
D) SUMMARY OF THE INVENITON
[0014] The above mentioned shortcomings, disadvantages and problems are addressed herein and which will be understood by reading and studying the following specification.
[0015] The various embodiments of the present invention provide a self actuated mechanism to eject and relieve the moulded parts with multiple start internal threads. According to one embodiment of the present invention,
A self actuated mechanism for ejecting components with multiple start internal threads has a core insert having a replica of the threaded profile formed on the component. A sleeve is formed around the core insert. The sleeve is rotated to move the molded

component axiaily along the length of the sleeve. The sleeve is fixed on a holder plate through taper roller bearings and ball bearings. The component is rotates and translates along the length of the sleeve due to the helical threaded profile on the core insert and on the component.
[0016] According to one embodiment of the present invention, a self actuated mechanism is provided for ejecting the components with multiple start internal threads. The component comprises double start internal threads as well as undercuts in its side way. The helical profile of the component is used to eject it after moulding.
[0017] According to one embodiment of the present invention, the component obtained from the injection mould tool is a cam. It includes double start internal threads with a pitch value of 60. The depth of the undercut produced is approximately 2mm. A self actuated mechanism is provided in the injection mouling tool to eject the component cam.
[0018] According to one embodiment of the present invention, the self ejection mechanism consists of a core insert with the replica of threaded profile required on component. The core insert is fixed to moving side of the mould. A sleeve surrounds the core insert, which forms the bottom portion of the component. The sleeve is fixed through the set of bearings to the holder plate. This whole mechanism will facilitate the removal of threaded component from the mould. The component will be ejected by a sleeve, which forms the bottom portion of the component. The component will be forced to rotate along the helical profile on the fixed core.

[0019] According to one embodiment of the present invention the smooth motion of the sleeve during the ejection of a moulded component is achieved by the use of a combination of taper roller bearing and ball bearing assemblies. The most striking feature here is the use of the helical thread profile for rotational movement of the component. The component will rotate and slide along the helix, thus facilitating the ejection of the component from the mould without damaging the component.
[0020] According to embodiment of the present invention, initially the mould is loaded on the injection-molding machine. After all the required setting to run the mould is completed, moving half of the machine moves forward and butt against the fixed half of the mold. During closing of the mould angle pin engage with the side core and move the side core in the forward position guided in the guide plate. Then the plastic material is injected in the mould. After material sets inside the mould the mould opens. The side core is retracted through angle pins, relieving the undercuts present in sideways. The component sticks to the moving sideline on the threaded core along with runner and gate. The threaded portion is an undercut in mould opening direction.
[0021] Once the molded component is retracted, the ejector mechanism is actuted. The sleeve is attached to this mechanism starts moving up along with it. The component is stucked on the threaded core insert (a stationary member).The sleeve starts pushing component upwards. The component is forced to move in upward direction, as the
E 1 APR 2009

/sticking force is smaller than the shearing strength of the component. The component starts moving along the helical threaded path hence ejecting the component.
[0022] Since the component moves along the helical threaded profile around the fixed core insert. All possible causes of resistance are tried to minimize by the help of bearing arrangement. This mechanism will facilitate the production of components with similar construction in much simplified way. Hence it provides an arrangement will allow component profile itself to eject and relieve the undercut without damaging the component profile.
E) BRIEF DESCRIPTION OF THE DRAWINGS
[0023] 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:
[0024] FIG. 1 shows a cross sectional view of the assembly of the mould provided with a self actuation mechanism according to one embodiment of the present invention, with fixed half and moving half in the mould in close condition.
[0025] FIG. 2 shows a cross sectional view of the assembly of the mould provided with a self actuation mechanism according to one embodiment of the present invention, with the mould assembly in open condition.

[0026] FIG .3 shows a cross sectional view of the assembly of the mould provided with a
self actuation mechanism according to one embodiment of the present invention, with
ejector assembly moving forward to eject the moulded component.
[0027] FIG .4 shows a cross sectional view of the component mould ejected from the molding assembly according to one embodiment of the present invention.
[0028] Although 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.
F) DETAILED DESCRIPTION OF THE INVENTION
[0029] In the following detailed description, 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.

[0030] The various embodiments of the present invention provide a self actuated mechanism to eject and relieve the moulded parts with multiple start internal threads.
According to one embodiment of the present invention,
A self actuated mechanism for components with multiple start internal threads has a core
insert having a replica of the threaded profile formed on the component. A sleeve is
formed around the core insert. The sleeve is rotated to move the molded component
axially along the length of the sleeve. The sleeve is fixed on a holder plate through taper
roller bearings and ball bearings. The component is rotates and translates along the
length of the sleeve due to the helical threaded profile on the core insert and on the
component.
[0031] According to one embodiment of the present invention, a self actuated mechanism is provided for ejecting the components with multiple start internal threads. The component comprises double start internal threads as well as undercuts in its side ways by using injection moulding tool. Then the helical profile of the component is used to eject it after moulding.
[0032] According to one embodiment of the present invention, the component obtained from the injection mould tool is a cam. It includes double start internal threads with a pitch value of 60. The depth of the undercut produced is approximately 2mm. A self actuated mechanism is provided in the injection moulding tool to eject the component cam.

/[0033] According to one embodiment of the present invention, the self ejection mechanism consists of a core insert with the replica of threaded profile required on component. The core insert is fixed to moving side of the mould. A sleeve surrounds the core insert, which forms the bottom portion of the component. The sleeve is fixed through the set of bearings to the holder plate. This whole mechanism will facilitate the removal of threaded component from the mould. The component will be ejected by a sleeve, which forms the bottom portion of the component. The component will be forced to rotate along the helical profile on the fixed core.
[0034] According to embodiment of the present invention, initially the mould is loaded on the injection-molding machine. After all the required setting to run the mould is completed, moving half of the machine moves forward and butt against the fixed half of the mold. During closing of the mould angle pin engage with the side core and move the side core in the forward position guided in the guide plate. Then the plastic material is injected in the mould. After material sets inside the mould the mould opens. The side core is retracted through angle pins, relieving the undercuts present in sideways. The component sticks to the threaded core along with runner and gate. The threaded portion is an undercut in mould opening direction.
[0035] Once the molded component is retracted, the ejector mechanism is actuted. The sleeve is attached to this mechanism starts moving up along with it. The component is stucked on the threaded core insert (a stationary member).The sleeve starts pushing component upwards. The component is forced to move in upward direction. The sticking

/force is smaller than the shearing strength of the component. The component starts moving along the helical threaded path which inturn ejects the component.
[0036] According to embodiment of the present invention, the sleeve is mounted on the combination of taper roller bearing and ball bearing. A heavy ejection load in axial direction comes on the sleeve. Angular roller bearing can take the axial load as well as radial load. The bearings allow the resistance free rotation of the sleeve. The roller ball bearing is used to have a positive loading of the taper roller bearing on the sleeve. The top face of the sleeve is provided with the matt finish. This will have a positive bonding with the component. This will help in getting initial thrust on the component. The component will be pushed upwards. The component along with sleeve can smoothly rotate with the bearing arrangement used. With this unique arrangement the component will rotate and slide along the helix which inum will relieve it from the mould.
[0037] FIG. 1 show a cross sectional view of the assembly of the mould fixed half and moving half in close condition according to one embodiment of the present invention. As shown in FIG. 1, the component is formed between the moving and the fixed half of the injection molding machine. The moving half of the injection moulding machine includes sleeve 108 which forms the casing of the core insert 109. The sleeve 108 is in physical contact with the taper roller bearing assembly 106. The punch housing 102 and the top plate 112 are attached to each other through a parallel 101 and the parallel 105. The ejector plate 103 holds the guide pins 104. The guide pins 104 passing through the guiding bush 113 in the top plate 112 connects the ejector plate 114 to the taper roller

Rearing assembly 106. The ball bearing assembly 107 is held in the mounting assembly by the bearing holder 111. An ejector plate 114 and the holder plate 115 are arranged in the assembly as shown in the figure. The side cores 116 and 117 are fixed to the punch housing 102 on moving half of the moulding machine to support the core insert. The fixed half of the machine comprises of a die housing 118. The insert 119 and the cavity insert 120 is provided in the fixed half to obtain the required shape on the moulded component. The fixed half of the molding machine includes a locating ring 121 and the nozzle 122.
[0038] Initially the mould is loaded on the injection-molding machine. After all the required setting to run the mould is completed, moving half of the machine moves forward and butt against the fixed half of the mold. During closing of the mould angle pin engage with the side core and move the side core in the forward position guided in the guide plate. Then the plastic material is injected in the mould. The material is then cooled till it gets solidified. The mould is then opened..
[0039] FIG. 2 shows a cross sectional view of the mould assembly in open condition when the side core moves back according to one embodiment of the present invention. After the material sets inside the mould, the mould is opened. The side core 116 and 117 are retracted through angle pins, relieving the undercuts present in sideways. The component 123 sticks to the moving side on the threaded core along with runner and gate. The threaded portion is an undercut in mould opening direction. Once the side cores are retracted, the ejector mechanism is actuated. The sleeve attached to this mechanism starts

/moving up along with it. The component gets attached to the threaded core insert 109. The sleeve 108 starts pushing component upwards. The component is forced to move in upward direction. As the sticking force is smaller than the shearing strength of the component, the component starts moving along the helical threaded path thereby ejecting the component.
[0040] FIG. 3 shows a cross sectional view of the mould assembly in open condition with ejector assembly moving forward to eject the moulded component according to one embodiment of the present invention. With respect to FIG. 3, once the molded component is retracted, the ejector 103 mechanism gets actuated. The sleeve 108 attached to this mechanism starts moving up along with it. Since the component gets attached to the threaded core insert 109, the sleeve 108 starts pushing component upwards. The component is forced to move in upward direction as the sticking force is smaller than the shearing strength of the component. The component starts moving along the helical threaded path hence ejecting the component 123.
[0041 ] The sleeve 108 is mounted on the combination of taper roller bearing 106 and ball bearing 107. A heavy ejection load in axial direction comes on the sleeve 108. Angular roller bearing 107 can take the axial load as well as radial load. The bearings allow the resistance free rotation of the sleeve 108. The roller ball bearing 107 ensures positive loading of the taper roller bearing 106 on the sleeve 108. The top face of the sleeve 108 is provided with the matt finish to provide positive bonding on the component. The component along with sleeve smoothly rotates with the bearing arrangement, So with this

'unique arrangement the component rotates and slides along the helix that inurn relieves it from the mould 123.
[0042] FIG. 4 shows a cross sectional view of the component ejected from the molding assembly according to one embodiment of the present invention. The component obtained is cam 123 with helical threads on its internal surface. This feature on the component helps in self ejection of the component from the mold.
[0043] The component moves along the helical threaded profile around the fixed core insert. All possible causes of resistance are tried to minimize by the help of bearing arrangement. This mechanism will facilitate the production of components with similar construction in much simplified way. Thus it provides an arrangement that will allow component profile itself to eject and relieve the undercut without damaging the component profile
G) ADVANTAGES OF THE INVENTION
[0044] Various embodiments of the present invention provide a self actuated mechanism to eject and relieve the moulded parts with multiple start internal threads. It comprises of designing a component with double start internal threads as well as undercuts in its side ways by using injection moulding tool. Then the helical threaded profile of the component is used to eject it after moulding. The helical thread profile is used for rotational movement of the component. The component will rotate and slide along the

helix, thus facilitating the ejection of the component from the mould without damaging the component.
[0045] Since the component moves along the helical threaded profile around the fixed core insert. All possible causes of resistance are tried to minimize by the help of bearing arrangement. This mechanism will facilitate the production of components with similar construction in much simplified way. It provides an arrangement that will allow component profile itself to eject and relieve the undercut without damaging the component profile
[0046] 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.

[0047] 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: March 30,2009 Place: Bangalore.

I
CLAIMS
What is claimed is:
1. A self actuated mechanism for ejecting components with single and multiple start
internal threads comprising:
a fixed core insert;
a sleeve formed around the fixed core insert;
wherein the sleeve rotates and moves axially along with the molded component to
eject the component out of mould.
2. The mechanism according to claim 1, wherein the core insert which is a stationary member has a replica of the threaded profile .of the component.
3. The mechanism according to claim 1, further comprising taper roller bearings and ball bearings to fix the sleeve to a holder plate in the moulding die.
4. The mechanism according to claim 1, wherein the component rotates and moves axially along the length of the sleeve due to the helical threaded profile on the core insert and on the component.
5. The mechanism according to claim 1, the component having threads is ejected out by using the ejection stroke of the mould only and without any unscrewing mechanism.

6. The mechanism according to claim 1, the component is self ejected by the helical profile on the component by pushing it with the sleeve and mechanism provided to reduce friction and allow free rotation to eject the part out.

To,
The Controller of Patents. The Patent Office, Mumbai