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:
PNEUMATIC EJECTION SYSTEM FOR COMPOUND DIES
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 compound dies for shearing in stamping operation and particularly relates to ejection mechanism for sheared component in a compound die assembly. The invention more particularly relates to a pneumatic ejection system for delicate and tiny component compound from die assembly.
B) BACKGROUND OF THE INVENTION
[0002] In a typical compound die system, adhesion of the sheared component to the pressure pad inhibits its ejection. This undesired adhesion of sheared component can be due to various factors like (a) atmospheric pressure acting on the component form one side and no pressure on the other side due to the absence of air gap between component and the pressure pad (b) adhesive force between different material of component and the pressure pad and (c) due to oil film between component and pressure pad. The oil is normally used in all type of press tools for smooth cutting operation. This oil forms a thin layer between the two and adds to sticking. The adhesion of sheared component is undesirable as the component which is cut remains inside the die and is held between the punch and the pressure pad. When the component is sticking to the punch (bottom side of tool) then it is visible and can be removed. But when the component sticks to the pressure pad (top side of the tool) then it might remain invisible due to the top side geometry of the pressure pad. This has a risk of operator taking the next stroke without removing the previous
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component sticking to the pressure pad. So it is essential to provide an arrangement which will remove the component from the pressure pad.
[0003] One of the currently available methods and widely used method for ejecting components form punch or pressure pad uses spring loaded ejector pin mechanism. In this method, the spring action of an ejector pin pushes the component off the pressure pad. One important limitation of this method is the relatively large space required for accommodating ejector pin and the spring. An assembly that is intended to produce tiny component, requires small punch or pressure pad making it difficult to accommodate the relatively large spring loaded ejector pin system. Additionally, a mechanical system that uses a spring will loosen its effectiveness over time due to the reduction in spring force. Furthermore, a contact based mechanical system if used for ejecting delicate components can lead to component damage due to the contact force exerted by the pushing action.
C) OBJECT OF THE INVENTION
[0004] The primary object of this invention is to develop a pneumatic component ejection system to eject tiny and delicate components in a compound die assembly.
[0005] Another object of the present invention is to provide a pneumatic component ejection system with controlled release of air jet to allow the compressed air to push the sheared component only after the cutting operation has finished and the sheared component is ready to be ejected.

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[0006] yet another object of the present invention is to provide cross holes for pneumatic component ejection system thereby reducing the cost of manufacturing.
[0007] 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 INVENTION
[0008] The above mentioned shortcomings, disadvantages and problems are addressed herein and which will be understood by reading and studying the following specification.
[0009] The various embodiments of the present invention provide a compound die assembly with a pneumatic component ejection system which uses air jet to eject sheared components adhering to the pressure pad or the punch after a shearing operation has finished according preferred embodiments of the invention.
[0010] According to one embodiment of the present invention, a pneumatic component ejection system is provided with a die having a sufficiently big hole. The hole in the die connects the air supplied from an external source to an annular space around the pressure pad. The annular space in the present invention is termed as 'air chamber'. The outer end of the hole though the die is tapped so that the air hose can be connected directly to the die. The location of this hole in the die can be anywhere depending on the side on which air hose and air pipe can be accepted without interfering in operation or to the operator. The close slide fit between die and the
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pressure pad in a compound die setup does not allow the air to escape from the gap between the die and the pressure pad.
[0011] The compound die has a pressure pad with cross and vertical holes in it. The air form the air chamber enters into the vertical holes of the pressure pad through the cross holes. The pressurized air in the vertical holes of the pressure pad collides with and ejects the sheared component adhering to the pressure pad after a shearing operation has finished. The air chamber around the pressure pad is large enough to facilitate a common space from where air can enter into any number of cross holes in the pressure pad. Size of the air chamber can be suitably adjusted so that the accurate location of cross holes in pressure pad is not required and liberal tolerance can be provided for the location of these cross holes. The number and size of the vertical holes in the pressure pad can be designed depending on the geometry of the component, location of ejection points required and overall space available for the ejection system on the component profile.
[0012] According to another embodiment of the invention, a pneumatic component ejection system with controlled release of the air jet is provided. This controlled release of the compressed air is facilitated by the relative motion of the pressure pad with the cross and vertical holes and the die with the air chamber. The controlled release allows the compressed air flowing through the vertical holes in the pressure pad to push the component adhering to the pressure pad only after the cutting operation has finished and the sheared component is ready to be ejected.
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E) BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The other objects, features and advantages will occur to those skilled in the art from the following description of the embodiments and the accompanying drawings in which:
[0014] FIG. 1 shows a sectional view of the compound die provided with a pneumatic component ejection system according to one embodiment of the present invention.
[0015] FIG, 2 shows the sectional view of the compound die provided with a pneumatic component ejection system according to one embodiment of the present invention, with a component clamped between the die and the pressure pad.
[0016] FIG. 3 shows the sectional view of the compound die provided with a pneumatic component ejection system according to one embodiment of the present invention, with the die unit moved downwards to cut a component out of the material strip.
[0017] Fig. 4 shows a sectional view of the compound die provided with a pneumatic component ejection system according to one embodiment of the present invention, with the die unit moved upwards and reconnecting air supply between air hole in die and the cross hole in the pressure pad.
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[0018] Fig. 5 shows a sectional view of the compound die provided with a pneumatic component ejection system according to one embodiment of the present invention, with sheared material component in ejected condition.
[0019] 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
[0020] In the following detailed description, reference is made to the accompanying drawings that form a part hereof, and in which the preferred embodiments that can be practiced is shown by way of illustrations. The embodiment is described in sufficient detail to enable those skilled in the art to practice the embodiment and it is to be understood that the logical, mechanical and other changes may be made without departing from the scope of the preferred embodiment. The following detailed description is therefore not to be taken in a limiting sense.
[0021] The assembly shown in FIG. 1 primarily includes a die unit 101, a pressure pad unit 105 and a punch unit 108. The die unit 101 has an air hole 103 running through it. The outer end of the air hole 103 is tapped 102 to connect an air hose directly to the die. The location of the air hole 103 on the die 101 can be anywhere depending on the side on which air hose and air pipe 103 can be accepted without
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interfering in operation or to the operator. The other end of the air hole 103 opens in an air chamber 104. The air chamber 104 is an annular space around the pressure pad
105. The pressure pad assembly contains number of cross holes 107 and vertical holes
106. Air from the air chambers 103 enters into the cross holes 107 in the pressure pad. The number and size of these cross holes 107 depends on the geometry of the cut component, location of ejection points required and overall space available for ejection system on the cut component profile. The pressurized air from the cross hole 107 enters the vertical holes 106 and finally get injected as a pressurized air jet on the cut component surface. Size of the air chamber 104 can be suitably adjusted so that the accurate location of the air hole 107 in pressure pad 105 is not required and liberal tolerance can be provided for the location of the cross hole 107. The path of air flow is detonated by arrows inside the body of the diagram shown as FIG. I.
[0022] With respect to FIG. 2, a materials strip 201 from which a component is intended to be sheared out is clamped between the pressure pad unit 105 and the punch 108. The clamping is achieved when the top assembly (die 101 and the pressure pad 105) connected to a ram of machine starts moving in downward direction. Due to this downward movement of the ram, the material strip 201 which initially is resting on the punch 108 surface is clamped between the punch 108 and the pressure pad 105. The movement of the top assembly of a compound die using a ram setup to clamp a material strip resting on the punch surface is a typical mode of operation of a compound die assembly for shearing of components. Additionally, as illustrated in figure 2, the location of the cross hole 107, at this point of time during the process, is such that its opening lays inside the air chamber 104 thus allowing air
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from the air hole 103 to enter into the vertical hole 106. The die 101 and the pressure pad 105 has close slide fit between them. This is the requirement from the tool functioning point of view. In the present invention this close fit prevents any escape of air from the gap between the die 101 and the pressure pad 105 ensuring that the air is only flowing through the channels intentionally provided for this purpose.
[0023] With respect to FIG. 3, the die 101 is moved downwards to cut a component 301 out of the material sheet 201. The shape of the cut component 301 is as per the profile of the die 101 and the punch 108. The upward movement of the pressure pad 105 relative to the die 101 places the cross hole 107 above the periphery of the air chamber 104, also shown in figure 3, thus disconnecting the supply of the air from the air hole 103 into the cross hole 107 and subsequently into the vertical hole 106 of the pressure pad 105. The component 301 which is cut is inside the die and is held between punch 108 and the pressure pad 105.
[0024] With respect to FIG. 4, the die 101 starts moving upwards relative to the punch 108 after the cutting of the component 301. This upward motion of the die 101 moves the pressure pad 105 downwards relative to the die 101 and places the cross hole 107 inside the periphery of the air chamber 104. This reconnection of the cross hole 107 and the air chamber 104 facilitates the flow of pressurized air (denoted by arrows in the body of the figure) into the vertical hole 106 of the pressure pad 105. This pressurized air jet finally hits the surface of the cut component 301.
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[0025] With respect to FIG. 5, the upward movement of the die 101 and pressure pad 105 assembly loosens the clamping of the cut component 301 which was previously mechanically held between the punch 108 and the pressure pad 105. At this stage, the alignment of the cross hole 107 and the air chamber 104 is maintained. The pressurized air flowing through the cross hole 107 into the vertical hole 106 of the pressure pad 105 and hitting the surface of the loosened cut component 301 and causes the ejection of the cut component 301.
G) ADVANTAGES OF THE INVENTION
[0026] The preferred embodiments of the present Invention provide a compound die assembly with a pneumatic component ejection system which uses air jet to eject sheared components adhering to the pressure pad or the punch. This invention is particularly useful in case when component is thin and tiny. The component being tiny, there is very small space available for accommodating any type of mechanical ejection system in the pressure pad, as pressure pad size and shape corresponds to that of the component. Since a hole of small size that can pass sufficient air for ejection of sheared component, the system can be used for tiny components. Also since there is not direct contact between the component and the ejection system, as in case of normal mechanical ejection mechanisms, the component does not damage. The absence of any physical contact between the ejection mechanism and the sheared component is particularly helpful in case of thin and fragile components.
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[0027] Another advantage of the present invention is the controlled release of the air jet. This controlled release of the compressed air is facilitated by the relative motion of the pressure pad containing the cross and vertical holes and the air chamber. The controlled release allows the compressed air flowing through the vertical holes in the pressure pad to push the component adhering to the pressure pad only after the cutting operation has finished and the sheared component is ready to be ejected.
[0028] Another advantage of the present invention is the reduction of cost associated with attaching a mechanical based ejection system into the pressure pad. Use of hollow cylindrical shaped air nozzles eliminates the cost associated with attaching any mechanical system.
[0029] 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, alf such modifications are deemed to be within the scope of the claims.
[0030] 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. RAKESH PRABHU
Place: Bangalore. Patent Agent

CLAIMS
What is claimed is:
1. A pneumatic component ejection system for compound die having punch,
press unit and pressure pad, to remove the tiny component stuck to pressure
pad, the system comprising:
an air chamber formed in the die;
an air hole connected to the air chamber;
an ejection unit formed in the die;
a vertical hole formed in the ejection unit; and
a cross hole connected to the vertical hole;
wherein the ejection unit is moved to connect the air hole in the air chamber
with the vertical hole in the ejection unit through the cross hole to blow out air
to the pressure pad to eject a component stuck to the pressure pad.
2. The system according to claim 1, wherein the ejection unit is moved upwards to disconnect the connection of the vertical hole from the air hole, after the removal of the component from the pressure pad.
3. The system according to claim 1, further comprises an air hose connected to the air hole to supply air to the air chamber.
4. The system according to claim 1, wherein the air chamber is the annular space provided around the pressure pad.
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5. The system according to claim I, wherein the size of the air chamber is arranged such that accurate location of the air holes in the pressure pad is not required for passing air to the pressure pad to eject the component stuck on the pressure pad.
Dated this the 30th day of March 2009
RAKESH PRABHU
Patent Agent,
ALMT Legal,
#2, Lavelle Road, Bangalore-560 001
To,
The Controller of Patents, The Patent Office, Mumbai

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