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:
PILOT ACTUATED PUSHER ASSEMBLY FOR COIL/STRIPS IN PRESS TOOLS
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 a press tool assembly and particularly to the press tools used for processing coils or strips in progressive punching operations executed during the manufacturing process of sheet metal components used in applications such as electrical/electronic products, automobiles, watches etc. The present invention more particularly relates'to provide a pilot actuated pusher assembly for coil or strip in press tools to provide a common reference for punching holes in coils without compromising the strength of the dies in the press tools.
B) BACKGROUND OF THE INVENTION
[0002] Press working is one of the major processing techniques for converting a sheet metal into the sheet metal parts of different shapes. The sheet metal parts are required for different applications such as electrical/ electronic products, automobiles, watches etc. The sheet metal is punched between two parts calleci a punch and a die. The die profile is the female profile intentionally kept bigger than the punch profile by a uniform gap called cutting clearance.
[0003] The press tool mainly consists of two halves, namely a fixed bottom half and a moving top half. The fixed bottom half is secured to the stationary bolster plate of a mechanical press. The bottom half comprises of an arrangement to guide the strip/coil, the die cavities, the guide pillars for alignment of both the halves etc. The top moving half is clamped to the moving ram of the mechanical press and it comprises a number of circular and non circular cutting and non cutting elements called punches. The punches move up and down along with the moving ram of the mechanical press and they are guided in cavities made in a plate called Stripper plate. During the downward movement, the punches penetrate the sheet metal and enter the die cavity thus pushing the sheet metal scrap displaced by the cutting punch into the lower half of the tool. One

downward and return upward movement of the top half of press tool is called as a stroke of the press tool. The surrounding metal clings to the body of the cutting punches during the downward stroke. The same is stripped off by the stripper plate during the upward stroke of the punches.
[0004] The press tools are of multi-station type or single station type. In a multistation tool, the strip moves from one end of the strip guides to the other end. It moves progressively by a fixed distance called pitch after every stroke of the mechanical press. At each stage of the movement of the strip, different punching operations are carried out on the strip / coil leading to the completion of a stamping profile in the last stage. The stampings have circular and non circular holes placed with respect to one edge of the component. The gap in the strip guides is always kept bigger than the maximum size of strip/coil width for ease of strip/coil feeding. It is not possible to ensure that the strip moves exactly at the reference side of the strip guide. The strip would move randomly and the position of the punched holes with respect to edges of coil width varies randomly. This will not allow the maintenance of component dimension with respect to one edge of the coil/strip leading to the rejection of the stampings by the quality control department.
[0005] The stampings have circular and non circular holes placed in such a way that the distance between a hole centre with respect to one edge of the component is very important and it is a critical quality dimension irrespective of the variation in the size of coil or strip. Moreover, there was no consistency in positioning the holes with respect to one edge of component to be punched.
[0006] In the conventional press tools, the spring loaded pushers are provided in the moving top half of the press tool. The hole positions in stamping are given from the edge of the component by design. The holes and other profiles in the component makes the die weak to withstand the tool load such as cutting load and bending load. The area to

provide the spring loaded pushers is very less thereby making the die wall more weak and prone to breakage.
[0007] Hence there is a need to eliminate the breakage of the die elements due to the conventional spring loaded pusher arrangement. Also there is a need to provide a press tool to achieve the sheet metal component requirements without compromising the strength of the die. Further there is a need to provide a constant reference for the punching of holes during the progressive punching operations and to maintain consistency in the position of the holes with respect to one edge of the component.
[0008] The above mentioned shortcomings, disadvantages and problems are addressed herein and which will be understood by reading and studying the following specification.
C) OBJECTS OF THE INVENTION
[0009] The primary object of the present invention is to provide a pilot actuated pusher assembly for coil or strip at one or more location in the press tools to align the strip or coil in press tools with respect to one edge of the component to be punched and to provide a constant reference for the punching of the holes.
[0010] Yet another object of the present invention is to provide a pilot actuated pusher assembly to withstand the tool load on the die elements during progressive punching operation thereby eliminating the breakage of the die elements.
[0011] Yet another object of the present invention is to provide a pilot actuated pusher assembly which is assembled easily and which requires less maintenance.

[0012] Yet another object of the present invention is to provide a pusher assembly to take care of the variation in strip /coil width and clearance in the guiding slot and maintain the consistency in the positioning of holes with respect to one edge of the component.
[0013] These and other objects and advantages of the present invention will become readily apparent from the following specification taken in conjunction with the accompanying drawings.
D) SUMMARY OF THE INVENTION
[0014] The various embodiments of the present invention provide a pilot actuated pusher assembly at one or more location in the press tool assembly to align the strip or coil in press tools with respect to one edge of the component to be punched and to provide a constant reference for the punching of the holes.
[0015] According to one embodiment of the present invention, a pilot actuated pusher assembly for coil/strips in a press tools has a pusher element provided in a stripper plate which is arranged in a press tool assembly. A first spring is provided at one end of the pusher element. A step is provided at another end of the pusher element. A tapered hole is formed on the pusher element. A stripper bush is provided in the stripper plate. A pilot member is held on a holder plate in the press tool assembly. A spacer is arranged above the pilot member. A second spring is arranged above the spacer. The pilot member is passed through the stripper bush to engage with the tapered hole on the pusher element to move the pusher element towards a strip,
[0016] The pusher element is an elongated element provided with a slot at one distal end. The first spring is arranged in the slot to hold the pusher element in position. The pusher element is guided through a slot provided in the stripper plate. The pusher

element has a radial shape in the front side to ensure a line of contact with the strip during working. The step structure is formed on the top surface of the pusher element to act as a stopper. The pusher element has a tapered hole to receive the pilot element.
[0017] The assembly further comprises a slot provided on the top face of a die plate in the press tool assembly to receive the stripper bush which is arranged around the pilot element. The pilot element is a cylindrical element. The pilot element has a collar on the top and a bullet shaped tip at the bottom. The bullet shaped tip has a tapered angle. The tapered angle of the bullet shaped tip is equal to the tapered angle of the tapered hole in the pusher element. The bullet shaped tip is received into the tapered hole of the pusher element to engage the pilot element with the pusher element during the downward stroke of the press tool to move the pusher element towards the strip.
[0018] The second spring is a spring with a light load and the spring force is designed such that to move the pusher element towards the spring and to overcome the spring force imparted by the first spring. The first spring has a load which is less than that of the second spring. The first spring has a force which is designed to bring the pusher back to the initial position during the upward stroke of the press tool thereby relieving the strip for the forward advancement. The spacer is guided inside the top plate to act as a guide for the second spring. The spacer is a cylindrical element with two steps.
[0019] According to one embodiment of the present invention, a pilot actuated pusher assembly is provided for coils/strips in a press tool assembly. The pushers are L-shaped sliding members provided to withstand the tool load on the die elements during the progressive punching operation and to eliminate the breakage of the die elements.
[0020] According to one embodiment of the present invention, the press tool assembly includes a fixed bottom half and a moving top half. The fixed bottom half comprises of a base plate. A die plate is clamped to the base plate. A strip or coil is

mounted on the die plate. A stripper plate is clamped to the die plate. The strip or coil is mounted against the strip butting surface on stripper plate to provide a constant reference for punching of holes. The L-shaped sliding pusher is guided in the slot provided between the stripper plate and the top surface of the die plate. The L-shaped pusher comprises of a taper hole and a provision for holding spring at the rear end. A step is provided on the top surface of the pusher. A stripper bush is provided in the stripper plate to guide the pilot precisely in to the die plate during progressive punching operation. The moving top half comprises of a pilot which is held in the holder plate. A spacer and spring is mounted in the top plate behind the pilot. The spacer is guided inside the top plate of the tool and also acts as a guide for the spring in the top plate. The pilot is precisely guided in the stripper bush mounted on the stripper plate during downward and upward stroke of the press tool.
[0021] According to one embodiment of the present invention, the pushers are L-shaped sliding members which are guided in the slot provided in between the stripper plate and top surface of the die plate. The pusher includes a provision to hold the spring at the rear end and the front side is radial in shape to ensure line contact with the strip / coil during punching operation. A compression spring is provided to hold the pusher in position. The spring is guided in the hole in the pusher. The pusher has a tapered hole which engages with the pilot mounted on the holder plate on the moving half. The step provided on the top surface of the pusher acts as a stopper.
[0022] The pilot is provided in the top half of the press tool. The pilots are cylindrical in shape with a collar on the top side and with a bullet shaped tip at the bottom side. The taper angle of the bullet in the pilot is kept the same as that on the pusher. The stripper bush is provided for guiding the pilot precisely in the bottom half of the press tool. The stripper bush is mounted on the stripper plate. The position of the stripper bush on the stripper plate is decided considering adequate wall thickness to the die plate for maximum strength. The pilot is well guided in the stripper bush provided in the stripper

plate. The diameter of the pilot is decided based on the strength to be imparted on the strip /coil.
[0023] The spacer is provided above the pilot to guide the compression spring provided in the top plate. The spacer is cylindrical in shape with two steps on its periphery. Any extra travel of the pilot is compensated by the spring provided above the spacer. The force of the spring provided above the spacer in the top half of press tool is sufficient to push the pusher towards the strip / coil. The spring force in the top plate is provided such that it overcomes the force of the spring assembled with the pusher in bottom half of press tool. The compression spring assembled with the pusher in the bottom half of the tool is provided to have sufficient force to bring the pusher back to the initial position during upward stroke of the tool, thus relieving the strip for forward advancement or pitching.
[0024] During downward stroke of the press tool, the bullet at the bottom side of the pilot engages with the tapered hole in the pusher thereby pushing the pusher in forward direction towards the strip / coil. The movement of the pusher is stopped, when the front portion of the pusher touches the strip and pushes it to butt against the guiding surface on the stripper plate. The remaining downward stroke of the press tool is compensated by the spring provided in the top plate of the press tool. The spring provided in the top plate starts compressing inside the top plate after the movement of the pusher is stopped. The compression spring provided behind the pusher gets compressed during the forward movement of the pusher, while pusher gets engaged with the strip / coil. During the upward stroke of the tool the spring provided in the top plate comes to the pre compressed condition and pilot starts moving up, thus relieving the pusher. The pusher moves back to the initial position with the help of spring. This relieves the strip / coil and makes it free for further pitching / advance movement. The backward movement of the pusher is restricted by the step provided in the stripper plate. The step on the top of the pusher gets engaged with the slot on the stripper and gets stopped.

[0025] The pilot actuated pusher arrangement is provided to align the strip or coils in the press tools and to provide a constant reference for positioning of the holes. It eliminates the tool load on the die elements during progressive punching operation and hence eliminates the breakage of the die elements. It ensures consistency in the positioning of holes with respect to one edge of the component. The pushers are designed such that it takes care of the variation in the strip or coil width. It takes care of the extra clearance in strip guides. The assembling and maintenance of the pilot actuated pusher is very easy.
E) BRIEF DESCRIPTION OF THE DRAWINGS
[0026] 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:
[0027] FIG.l shows a sectional view of atypical press tool assembly, provided with a pilot actuated pusher assembly according to one embodiment of the present invention.
[0028] FIG. 2 shows a sectional view of the press tool assembly provided with a pilot actuated pusher assembly during the downward stroke of the punch, according to one embodiment of the present invention.
[0029] FIG. 3 shows a sectional view of the press tool assembly provided with a pilot actuated pusher assembly, when the punch is moved fully in downward direction, according to one embodiment of the present invention.

[0030] FIG. 4 shows a side sectional view and the top plan view of a pusher element in a pilot actuated pusher assembly for coil/strips in a press tool, according to one embodiment of the present invention.
[0031] FIG. 5 shows a sectional view of a stripper bush provided in a pilot actuated pusher assembly for coil/strips in a press tool, according to one embodiment of the present invention.
[0032] FIG. 6 shows a sectional view of a pilot provided in a pilot actuated pusher assembly for coil/strips in a press tool, according to one embodiment of the present invention.
[0033] FIG. 7 shows a sectional view of a spacer provided in a pilot actuated pusher assembly for coil/strips in a press tool, according to one embodiment of the present invention.
[0034] 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
[0035] 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.

[0036] The various embodiments of the present invention provide pilot actuated pushers at one or more location in the press tool assembly to align the strip or coil in press tools with respect to one edge of the component to be punched and to provide a constant reference for punching of holes.
[0037] According to one embodiment of the present invention, a pilot actuated pusher assembly for coil/strips in a press tools has a pusher element provided in a stripper plate which is arranged in a press tool assembly. A first spring is provided at one end of the pusher element. A step is provided at another end of the pusher element. A tapered hole is formed on the pusher element. A stripper bush is provided in the stripper plate. A pilot member is held on a holder plate in the press tool assembly. A spacer is arranged above the pilot member. A second spring is arranged above the spacer. The pilot member is passed through the stripper bush to engage with the tapered hole on the pusher element to move the pusher element towards a strip.
[0038] The pusher element is an elongated element provided with a slot at one distal end. The first spring is arranged in the slot to hold the pusher element in position. The pusher element is guided through a slot provided in the stripper plate. The pusher element has a radial shape in the front side to ensure line contact with the strip during working. The step structure is formed on the top surface of the pusher element to act as a stopper. The pusher element has a tapered hole to receive the pilot element.
[0039] The assembly further comprises a slot provided on the top face of a die plate in the press tool assembly to receive the stripper bush which is arranged around the pilot element. The pilot element is a cylindrical element. The pilot element has a collar on the top and a bullet shaped tip at the bottom. The bullet shaped tip has a tapered angle. The tapered angle of the bullet shaped tip is equal to the tapered angle of the tapered hole in the pusher element. The bullet shaped tip is received into the tapered hole of the pusher

element to engage the pilot element with the pusher element during the downward stoke of the press tool to move the pusher element towards the strip.
[0040] The second spring is a spring with a light load and the spring force is designed such that to move the pusher element towards the spring and to overcome the spring force imparted by the first spring. The first spring has a load which is less than that of the second spring. The first spring has a force which is designed to bring the pusher back to the initial position during the upward stroke of the press tool thereby relieving the strip for the forward advancement. The spacer is guided inside the top plate to act as a guide for the second spring. The spacer is a cylindrical element with two steps.
[0041] According to one embodiment of the present invention, the pushers are L-shaped sliding members which are guided in the slot provided in between the stripper plate and top surface of the die plate. According to one embodiment of the present invention, the press tool assembly includes a fixed bottom half and moving top half. The fixed bottom half comprises of a base plate. A die plate is clamped to the base plate. A strip or coil is mounted on the die plate. A stripper plate is clamped to the die plate. The strip or coil is mounted against the strip butting surface or guiding surface on stripper plate to provide a constant reference for punching of holes. An L-shaped sliding pusher is guided in the slot provided between the stripper plate and the top surface of the die plate. The L-shaped pusher comprises of a taper hole and a provision for holding spring at the rear end. A step is provided on the top surface of the pusher. A stripper bush is provided in the stripper plate to guide the pilot precisely in to the die plate during progressive punching operation. The position of the stripper bush on the stripper plate is decided considering adequate wall thickness to the die plate for maximum strength. The moving top half comprises of a pilot which is held in the holder plate. A spacer and spring is mounted in the top plate behind the pilot. The spacer is guided inside the top plate of the tool and also acts as a guide for the spring in the top plate. The pilot is

precisely guided in the stripper bush mounted on the stripper plate during downward and upward stroke of the press tool.
[0042] According to one embodiment of the present invention, the pushers are L shaped sliding members which are guided in the slot provided in between the stripper plate and top surface of the die plate. The pusher includes a provision to hold the spring at the rear end and the front side is radial in shape to ensure line contact with the strip / coil during punching operation. A compression spring provided holds the pusher in position. The spring is guided in the hole in the pusher. The pusher has a tapered hole which engages with the pilot mounted on the holder plate on the moving half. The step provided on the top surface of the pusher acts as a stopper.
[0043] According to one embodiment, the pilot is provided in the top half of the press tool. The pilots are cylindrical in shape with a collar on the top and with a bullet shaped tip at the bottom side. The taper angle of the bullet is kept the same as that on the pusher. The stripper bush is provided for guiding the pilot precisely in the bottom half of the press tool. The stripper bush is mounted on the stripper plate. The position of the stripper bush on the stripper plate is decided considering adequate wall thickness to the die plate for maximum strength. The pilot is well guided in the stripper bush provided in the stripper plate. The diameter of the pilot is decided based on the strength to be imparted on the strip /coil.
[0044] The spacer is provided above the pilot to guide the compression spring provided in the top plate. The spacer is cylindrical in shape with two steps on its periphery. Any extra travel of the pilot is compensated by the spring provided above the spacer. The force of the spring provided above the spacer in the top half of press tool is sufficient to push the pusher towards the strip / coil. The spring force in the top plate is provided such that it overcomes the force of the spring assembled with the pusher in bottom half of press tool. The compression spring assembled with the pusher in the

bottom half of the tool is provided to have sufficient force to bring the pusher back to the initial position during upward stroke of the tool, thus relieving the strip for forward advancement or pitching.
[0045] During downward stroke of the press tool the bullet at the bottom side of the pilot engages with the tapered hole in the pusher. This pushes the pusher forward towards the strip / coil. The movement of the pusher is stopped when the front portion of the pusher touches the strip and pushes it to butt against the guiding surface on the stripper plate. The remaining downward stroke of the press tool is compensated by the spring provided in the top plate of the press tool. The spring provided in the top plate starts compressing inside the top plate after the movement of the pusher is stopped. The compression spring provided behind the pusher gets compressed during the forward movement of the pusher, while pusher gets engaged with the strip / coil. During the upward stroke of the tool the spring provided in the top plate comes to the pre compressed condition and pilot starts moving up, thus relieving the pusher. The pusher moves back to the initial position with the help of spring. This relieves the strip / coil and makes it free for further pitching / advance movement. The backward movement of the pusher is restricted by the step provided in the stripper plate. The step on the top of the pusher gets engaged with the slot on the stripper and gets stopped.
[0046] The pilot actuated pusher arrangement is provided to align the strip or coils in the press tools and to provide a constant reference for positioning of the holes. It eliminates the tool load on the die elements during progressive punching operation and hence eliminates the breakage of the die elements. It ensures consistency in the positioning of holes with respect to one edge of the component. The pushers are designed such that it takes care of the variation in the strip or coil width. It takes care of the extra clearance in strip guides. The assembling and maintenance of the pilot actuated pusher is very easy.
14

[0047] FIG. 1 shows a sectional view of a typical press tool assembly, provided with a pilot actuated pusher assembly according to one embodiment of the present invention. With respect to F1G.1, the press tool assembly mainly consists of two halves, namely fixed bottom half and moving top half. The fixed bottom half is secured to the stationary bolster plate of mechanical press. It comprises of an arrangement to guide the strip/coil, die cavities, guide pillars for alignment of both halves etc. The top moving half is clamped to the moving ram of the mechanical press and it comprises a number of circular and non circular cutting and non cutting elements called punches 8. The base plate 2 is clamped to the fixed bottom part. The die plate 3 is clamped on the base plate 2 with the strip or coil to be punched is guided on the die plate 3. The stripper plate 5 is clamped to the die plate 3. The top plate 1 is clamped to the moving top half. The holder plate 6 is clamped to the top plate 1. The holder plate holds the punches 8. The punches 8 move up and down along with the moving ram of the mechanical press and they are guided in cavities made in a plate called stripper plate 5. During downward movement, the punches 8 penetrate the sheet metal and enter the die cavity thus pushing the sheet metal scrap displaced by the cutting punch into the lower half of the tool. The surrounding metal clings to the body of cutting punches during downward stroke. The same is stripped off by the stripper plate 5 during upward stroke of the punches 8.
[0048] FIG. 2 shows a sectional view of the press tool assembly provided with a pilot actuated pusher assembly during the downward stroke of the punch, according to one embodiment of the present invention. With respect to FIG.2, the press tool assembly has a fixed bottom half and moving top half. The fixed bottom half comprises of a base plate 2. The die plate 3 is clamped to the base plate 2. The strip or coil 4 is mounted on the die plate 3. The stripper plate 5 clamped to the die plate 3. The strip or coil 4 is mounted against the strip butting surface or guiding surface 7 in stripper plate 5 to provide a constant reference for punching of holes. The L-shaped sliding pusher 10 is guided in the slot provided between the stripper plate 5 and the top surface of the die plate 3. The L-shaped pusher 10 comprises of a taper hole and a provision for holding the spring 11

at the rear end. A step is provided on the top surface of the pusher 10. A complementary slot 12 is provided in the stripper plate to stop the backward movement of the pusher 10. The stripper bush 9 is provided in the stripper plate 5 to guide the pilot 14 precisely in to the relief hole 13 on the die block during progressive punching operation. The position of the stripper bush 9 on the stripper plate 5 is decided considering adequate wall thickness to the die plate 3 for maximum strength.
[0049] The moving top half comprises of a pilot 14 which is held in the holder plate 6. The pilots 14 are cylindrical in shape with a collar on the top and with a bullet shaped tip at the bottom side. The taper angle of the bullet is kept the same as that on the pusher 10. This is well guided in the stripper bush 9 provided in the stripper plate 5. The diameter of the pilot 14 is decided based on the strength to be imparted on the strip / coil 4. The spacer 15 and the spring 16 are mounted in the top plate behind the pilot 14. The spacer 15 is cylindrical in shape. It has two steps. It is guided inside the top plate of the tool and also acts as a guide for the spring 16 in the top plate.
[0050] A pilot 14 held on the holder plate 6 of the top half engages with the taper hole in the pusher 10. The taper angle of the hole in the pusher 10 and the angle on the bullet of the pilot 14 are kept the same. The pilot 14 is well guided in the stripper bush 9. The spacer 15 is provided above the pilot 14 to guide the compression spring 16 provided in the top plate 1. Any extra travel of the pilot 14 is compensated by the spring 16 provided above the spacer 15. During downward stroke of the press tool the bullet at the bottom side of the pilot 14 engages with the taper hole in the pusher 10. This pushes the pusher 10 forward towards the strip or coil 4.
[0051] FIG. 3 shows a sectional view of the press tool assembly provided with a pilot actuated pusher assembly, when the punch is moved fully in downward direction, according to one embodiment of the present invention. With respect to FIG. 3, the pilot 14 held in the holder plate 6 is precisely guided in the stripper bush 9 mounted on the

stripper plate 5. During downward stroke of the press tool, the bullet at the bottom side of the pilot 14 engages with the tapered hole in the pusher 10. This pushes the pusher 10 forward towards the strip / coil 4. The movement is stopped when the front portion of the pusher 10 touches the strip and pushes it to butt against the guiding surface on the stripper plate 5. The remaining downward stroke of the press tool is compensated by the spring 16 in the top plate. The spring 16 starts compressing inside the top plate 1 after the movement of the pusher 10 is stopped. The compression spring 11 provided behind the pusher 10 gets compressed during the forward movement of the pusher 10 while pusher 10 gets engaged with the strip /coil 4,
[0052] During the upward stroke of the tool the spring 16 comes to the pre compressed condition and pilot 14 starts moving up, thus relieving the pusher 10. The pusher 10 moves back to the initial position with the help of spring 11. This relieves the strip / coils 4 and makes it free for further pitching / advance movement. The backward movement of the pusher 10 is restricted by the step provided in the stripper plate. The step on the top of the pusher gets engaged with the slot 12 in the stripper plate 5 and gets stopped.
[0053] FIG. 4 shows a side sectional view and the top plan view of a pusher element in a pilot actuated pusher assembly for coil/strips in a press tool, according to one embodiment of the present invention. With respect to FIG. 4, the pusher 10 is an L-shaped sliding member guided in the slot provided between the stripper plate and the top surface of the die plate. The L-shaped pusher comprises of a taper hole and a provision for holding the spring at the rear end. A step is provided on the top surface of the pusher. The compression spring provided holds the pusher 10 in position. The spring is guided in the hole in the pusher. The front portion of the pusher 10 is radial in shape. This ensures only a line contact with the strip / coil during punching operation. The tapered hole on the pusher engages with the pilot mounted on the holder plate on the moving half. The step provided on the top surface of the pusher acts as a stopper. The spring

provided in the pusher 10 should have sufficient force to bring the pusher 10 back to initial position during the upward stroke of the tool.
[0054] FIG. 5 shows a sectional view of a stripper bush provided in a pilot actuated pusher assembly for coil/strips in a press tool, according to one embodiment of the present invention. With respect to FIG. 5, the stripper bush 9 is provided for guiding the pilot 14 precisely in the relief hole on the die block. The stripper bush 9 is mounted on the stripper plate 5. The position of the stripper bush 9 on the stripper plate 5 is decided considering adequate wall thickness to the die plate 3 for maximum strength.
[0055] FIG. 6 shows a sectional view of a pilot provided in a pilot actuated pusher assembly for coil/strips in a press tool, according to one embodiment of the present invention. With respect to F1G.6, the pilot 14 is cylindrical in shape with a collar on the top and with a bullet shaped tip at the bottom side. The taper angle of the bullet is kept the same as that on the pusher. This is well guided in the stripper bush provided in the stripper plate. The diameter of the pilot 14 is decided based on the strength to be imparted on the strip /coil.
[0056] FIG. 7 shows a sectional view of a spacer provided in a pilot actuated pusher assembly for coil/strips in a press tool, according to one embodiment of the present invention. With respect to FIG. 7, the spacer 15 is cylindrical in shape with two steps on its periphery. It is guided inside the top plate of the press tool and it acts as a guide for spring in the top plate.
G) ADVANTAGES OF THE INVENTION
[0057] The various embodiments of the present invention provide a pilot actuated pusher arrangement to align the strip or coils in the press tools and to provide a constant reference for positioning of the holes. It withstands the tool load on the die elements

during progressive punching operation and hence eliminates the breakage of the die elements. It ensures consistency in the positioning of holes with respect to one edge of the component. The pushers are designed such that it takes care of the variation in the strip or coil width. It takes care of the extra clearance in strip guides. The assembling and maintenance of the pilot actuated pusher is very easy.
[0058] 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.

[0059] 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: October 26, 2009 Place: Bangalore.

CLAIMS
What is claimed is:
1. A pilot actuated pusher assembly for coil/strips in press tools comprising:
A pusher element provided in a stripper plate arranged in a press tool assembly;
A first spring provided at one end of the pusher element;
A step provided at another end of the pusher element;
A tapered hole formed on the pusher element;
A stripper bush provided in the stripper plate;
A pilot member held on a holder plate in the press tool assembly;
A spacer arranged above the pilot member; and
A second spring arranged above the spacer;
Wherein the pilot member is passed through the stripper bush to engage with the
tapered hole on the pusher element to move the pusher element towards a strip.
2. The assembly according to claim 1, wherein the pusher element is an elongated element.
3. The assembly according to claim 1, wherein the pusher element has a slot provided at one distal end.
4. The assembly according to claim 1, wherein the first spring is arranged in the slot provided at one distal end to hold the pusher element in position.
5. The assembly according to claim 1, wherein the pusher element is guided through a slot provided in the stripper plate.
6. The assembly according to claim 1, wherein the pusher element has a radial shape in the front side to ensure line contact with the strip during working.

7. The assembly according to claim 1, wherein the step structure is formed on the top surface of the pusher element to act as a stopper.
8. The assembly according to claim 1, wherein the pusher element has a tapered hole to receive the pilot element.
9. The assembly according to claim 1 further comprises a slot provided on the top face of a die plate in the press tool assembly to receive the stripper bush.
10. The assembly according to claim 1, wherein the pilot element is a cylindrical
element.
11. The assembly according to claim 1, wherein the pilot element has a collar on the top.
12. The assembly according to claim 1, wherein the pilot element has a bullet shaped tip at the bottom,
13. The assembly according to claim 1, wherein the bullet shaped tip has a tapered
angle.
14. The assembly according to claim 1, wherein tapered angle of the bullet shaped
tip is equal to the tapered angle of the tapered hole in the pusher element.
15. The assembly according to claim 1, wherein the bullet shaped tip is received into
the tapered hole of the pusher element to engage the pilot element with the
pusher element during the downward stoke of the press tool to move the pusher
element towards the strip.

16. The assembly according to claim 1, wherein the second spring is a spring with a
light load and the spring force is designed such that to move the pusher element
towards the spring and to overcome the spring force imparted by the first spring.
17. The assembly according to claim 1. Wherein the first spring has a load which is
less than that of the second spring.
18. The assembly according to claim 1, wherein the first spring has a force which is designed to bring the pusher back to the initial position during the upward stroke of the press tool thereby relieving the strip for the forward advancement.
19. The assembly according to claim 1, wherein the spacer is a cylindrical element with two steps.
20. The assembly according to claim 1, wherein the spacer is guided inside the top plate to act as a guide for the second spring.