FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
The Patents Rules, 2003
COMPLETE SPECIFICATION
(See section 10; rule 13)
1. Title of the invention: BENDING DIE ASSEMBLY HAVING UNIQUE
AUTOMATIC EJECTION ARRANGEMENT FOR EJECTING WORKPIECE FROM SAID DIE ASSEMBLY
2. Applicant(s):
(a) NAME : LARSEN & TOUBRO LIMITED
(b) NATIONALITY : An Indian company
(c) ADDRESS : L&T House, Ballard Estate, Mumbai 400 001,
State of Maharashtra, India
3. PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner in which it is to be performed:

FIELD OF THE INVENTION
The present invention relates to a bending die assembly having a unique ejection arrangement for automatic ejection of a workpiece after each bending operation. More particularly, the invention is concerned about automatic ejection of a workpiece from bending die assembly after a bending operation such that the workpiece can be taken out of the bending die assembly positively maintaining greater safety to the operator.
BACKGROUND OF THE INVENTION
Press tools are used for processing coils/strip. Operations like Piercing, Blanking, Bending, Forming, Coining, Perforating, Hole flanging, etc. are performed in Press tools.
The geometry of the workpiece and the quantity required makes it difficult to process the workpiece in Progressive dies. These workpieces are manufactured in stage wise operations. So operations like blanking, coining, bending etc. are performed in separate press tools in a sequential manner (Stage tooling).
Press tool mainly consists of two halves, namely fixed bottom half and a moving top-half. The fixed bottom half is secured to the stationary bolster plate of mechanical press. It comprises arrangement to place and locate the workpiece, die block, ejector block, heel block, c frame, stopper pin, ejector pins, locating pins, guide pillars for alignment of both halves etc. The top moving half is clamped to the moving ram of the mechanical press & it comprises of a top plate, binding punch etc. This top half moves up & down along with the moving ram of the mechanical press. During downward movement, the punches comes in contact with the sheet metal & holds the workpiece with the ejector block and bends it against the die. One downward & return upward movement of the top half of press tool is called as stroke of press tool.

Sometimes the workpiece moves up with the bending punch. This is pushed down with the help of spring loaded striker pins housed inside the punch. In the case of stage tooling the earlier bent feature gets disturbed when we uses striker pins to remove the workpiece from the bending punch. In this case the workpiece is taken out of the tool by a manually operated arrangement assembled in the tool or manually.
The manufacturing process for sheet metal workpiece or stamping is by processing a sheet metal coil or strip in a press tool. The sheet metal strip or coil may be of ferrous or non ferrous materials.
Press working is one of the major processing techniques for converting sheet metal into sheet meta) parts of different shapes. The she& metal parts are required for different applications such as Electrical / electronic products, Automobiles, Watches etc. The sheet metal is punched between two parts called punch & die. The die profile is the female profile intentionally kept bigger than the punch profile by a uniform gap which is equal to sheet thickness.
In a bending die normally a workpiece is bent against a die block and a spring loaded ejector block with the help of a punch. The finished geometry of the workpiece is decided by the Punch, Die and the ejector block. Sometimes the same workpiece has to undergo a number of bending operations when the workpiece has multiple bend features in it. So the earlier bend feature becomes an obstruction for removing/ejecting the workpiece out of the bending die.
The workpiece has to be taken out of the tool before the next stroke of the press. This is either done by some mechanisms which are manually operated or manually by the operator himself with his hand. It is risky to remove the workpiece using hand since the operator has to put his hand inside the press and the tool. This may lead to accidents and may cause permanent disability to operator.

US 4,068,520 discloses an ejector mechanism mounted on a press bed and includes an ejector member which is hydraulically actuated by a pair of opposed cams movable with the press slide and operable through corresponding hydraulic piston followers to achieve displacement of the ejector member during movement of the slide away from the press bed. The ejector mechanism further includes a hydraulic piston and cylinder assembly is attached to intermediate plate of the ejector assembly frame by means of a plurality of rods. The upward movement of piston causes upward displacement of ejector pin member, thus to eject the formed workpiece from die member. During the ensuing movement of slide toward bed plate, cam blocks move downwardly, whereby cam tracks allow pistons to move axially outwardly with respect to chamber. Such outward movement is under the influence of air under pressure in chamber biasing piston to move downwardly relative to chamber. In the event of a pressure overload in the hydraulic system during actuation of the ejector mechanism, valve responds to dump fluid in the system to sump. However, it was not known from the prior art that unique ejection arrangement having a uniquely designed cam means can provide in less number of elements used and make the assembly cost effective and accident proof. Further no simple arrangements for ejecting the workpiece from the bending tool has been disclosed in the prior art.
US 4,513,600 discloses an ejector device having ejector arms that are positively reciprocated by a cam assembly throughout their forward or extending movement and their rearward or retracting movement. Properly contoured cam surfaces accelerate the ejector arms more slowly to a position where they contact the shells to be ejected, thereafter rapidly accelerate the arms to eject the shells and then retract the arms from the slide area. This minimizes the impact against the edges of the shells, thereby preventing their deformation, and also allows the shell press to be operated at optimum speed. Furthermore, by eliminating the use of springs in the ejector mechanism, the present invention eliminates fatigue and failure problems associated with springs, and provides a quieter operating cam actuated ejector. However, it was

not known from the prior art that unique ejection arrangement having a uniquely designed cam means can provide in less number of elements used and make the assembly cost effective and accident proof. Further no simple arrangements for ejecting the workpiece from the bending tool has been disclosed in the prior art.
The disadvantages of the existing bending assemblies are
1. Removal of workpiece by manually operated mechanism or manually by operator himself by his hand make the process of removal of the workpiece risky and accident prone.
2. During bending operations the workpiece gets stick to the bending punch and it is difficult to remove the workpiece
3. Removal arrangement for removing workpiece from the press tool as described hereinabove requires an independent operation to actuate the mechanism for removing / ejecting the workpiece from the tool. This results in the complexity and increase in the number of elements used in the assembly thereby increasing the overall cost.
Thus there is a need to provide for a bending die assembly comprising a unique automatic ejector arrangement to remove the workpiece from the bending die without disturbing the earlier bent features and in a safe and effective manner and avoids the risk of manual operations such as accidents and cause disability to operator involved during removal of workpiece from the tool. The invention avoids using striker pins to remove the workpiece from the bending punch.

OBJECTS OF THE INVENTION
An object of the present invention is to overcome the problems/disadvantages of the prior art.
Another object of the present invention is to provide a bending die assembly having a unique ejection arrangement for automatic ejection of a workpiece after a bending operation.
Another object of the present invention is to provide a wedge shaped cam for automatic ejection of workpiece from the bending dies.
Another object of the present invention is to provide a spring means for just pushing of the workpiece from the bending dies.
Another object of the present invention is to provide a simple and compact arrangement for automatic ejection of workpiece from the bending dies.
SUMMARY OF THE INVENTION
According to one aspect of the present invention there is provided a bending die assembly having a unique ejection arrangement for automatic ejection of a workpiece after each bending operation, said assembly comprising: a movable top plate;
a fixed base plate located in proximity to said top plate and mechanically engaged to it by means of a support means which mechanically engages said top plate to the base plate, said top plate being movable along said support means in a vertical plane; bending punch located in fixation to below front half of said top plate for bending the workpiece as desired;guiding arrangement located in the rear half of said top plate, said guiding arrangement comprising plurality of guide rail means; guide block

means having stepped profile so as to co-operate with said guide rails during bending
operation, said guide block means being movable in substantially horizontal plane
between said rail means;
wherein said guide block means having tapered profile substantially at its center;
a cam means fixed to said base plate in a substantially vertical plane;
a spring assembly means operatively mounted on said guide block means at its rear
portion so as to provide the guide block with a resilient to and fro motion;
an ejector assembly means comprising ejector members and ejector block means, said
ejector members being operatively mounted on the rear side of the said bending
punch and said ejector block being fixed to the base plate in a substantial aligned
position with the bending punch;
wherein said cam means having tapered profile substantially at the middle portion
such that downward stroke of said top plate provides cooperative engagement
between said tapered surfaces of the cam means and the guide block means thereby
providing a substantial horizontal backward resilient motion of said guide block
means upto a predetermined position so as to compress the said spring such that
during upward stroke of the said top piate the tapered profile of the cam means
provides a substantial horizontal forward resilient motion of said guide block means
thereby actuating said ejector members in a manner that the workpiece is just ejected
from the bending punch.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Fig.l illustrates a bottom half plan view of the bending tool showing the various elements and their positions in the bending tool
Fig.2 illustrates a top half plan view of the bending tool showing the positions of the various elements of the bending tool

Fig.3 illustrates a sectional elevation of bending tool showing the tool in the downward stroke condition. The workpiece is bend and has clung to the bending punch at the previously bend region
Fig.4 illustrates a sectional side view of bending tool showing the ejector arrangement and the various elements in the mechanism
Fig.5 illustrates a sectional view of bending tool showing ejector cam, guide rails, guide block & spacer. The step and guiding surfaces of guide rails and guide blocks & clamping & locating of the same are also shown.
Fig.6 illustrates a drawing of the workpiece with multiple bends
Fig.7 illustrates a first bending
Fig.8 illustrates a second bending
Fig.9 illustrates an ejector cam
Fig.10 illustrates a guide block
Fig.l1 illustrates a guide rail
Fig.12 illustrates a spacer
Fig.13 illustrates a wear plate
Fig.14 illustrates a sleeve
Fig.15 illustrates a clamping plate
Fig.16 illustrates a holder plate
Fig.17 illustrates a ejector pin
Fig.18 illustrates a bending die in the upward stroke condition.

Fig.19 illustrates a bending tool in the downward stroke.
Fig.20 illustrates a bending tool in the downward stroke with travel still pending.
Fig.21 illustrates a bending tool in the downward stroke
Fig.22 illustrates a workpiece with bending operation completed.
Fig.23 illustrates a bending tool in the fully downward stroke condition.
Figure 24 shows workpiece taken up by the bending punch.
DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS
According to this invention a bending die assembly having a unique ejection arrangement is provided at the rear side of the press tool, behind the bending punch (1). The arrangement comprising a cam means an ejector cam (2) which is mounted & located precisely inside the slot provided in the base plate (13). A guide block means (3), a spacer(4), a holder plate (5) for holding the ejector members (6), guide rails (7), clamping plate (8) and a spring assembly (9) is assembled to the top half of the press tool. The guide block means is a guide block and the ejector member means are ejector pins (6). The spring assembly (9) is mounted on the guide block (3). This assembly comprises a compression spring (9a), sleeve (9b), washer (9c) and an alien screw (9d).
The spring is light load spring. It is provided behind the guide block (3) and is secured between the clamping plates (8). The spring (9a) is selected according to the stroke required, load required and considering the weight of the workpiece (10). The load of the spring (9a) is kept appropriate such that it just pushes the workpiece (10) out of the bending punch (1). Higher load of the spring (9a) may lead to accident and may be harmful to the operator and also will cause damage to the workpiece (10).

A hardened wear plate (11) is mounted inside the spacer (4) to give maximum support and guiding for the ejector cam. The ejector cam is a hardened member. It has the shape of a dog leg cam. It has two planar surfaces and angular (tapered) surfaces on both sides. Normally the tapered angle is kept between! Sdegree to 25degree. The tapered surface is perfectly guided inside the cavity provided in the guide block.
During the downward stroke of the press the ejector cam (2) engages with the guide block (3). The tapered surface of the guide block (3) gets engaged with the tapered surface of the ejector cam (2). The engagement of the tapered surface pushes the guide block (3) & moves it backward during downward stroke. Thus the ejector pin (6) gets cleared from the bending region of the bending punch (1). The compression spring (9a) is in the compressed state at this time. At the completion of the bottom most strokes the bending punch (]) gets engaged with the workpiece (10) and bends the workpiece (10) against the die block (14). The previously bend feature goes inside the opening in the bending punch (I).
During upward stroke the tapered surface on the rear side of the ejector cam (2) comes in contact with the tapered angle of the guide block (3), thus pushing the guide block forward. This movement takes the ejector pins (6) forward and hence the ejector pins comes in contact with the workpiece (10) and pushes the workpiece forward. During this time the compression spring (9a) slowly comes to the pre compressed state.
Fig.9 shows an ejector cam or wedge cam (2), which is a hardened member. This shape of the wedge cam is like a dog leg cam. The tapered surfaces on the front and rear faces are used for positive forward and reverse movements for the Guide block (3). There are straight lands at the bottom and the top side after the tapered surface. This is for providing delay for the ejection and for accommodating the extra travel (stroke) of the tool. The wedge cam is precisely located and clamped to the base plate (13).

Fig.10 shows a guide block (3), which is a hardened member and is mounted on to the top half of the bending tool. This is precisely guided between the spacer (4) and the guiderails (7). The guide block (3) travels forward and backward during the upwards and downward stroke of the top half of the tool. This has a tapered cavity at its centre for precisely guiding the wedge cam (2). The cavity in the guide block (3) also has tapered surfaces. The taper angle is same as that on the ejector cam (2). The engagement of tapered surface during the stroke of the press gives the forward and backward movement to the guide block (3). The spring assembly (9) is mounted at the rear side of the guide block (3). A holder plate (5) and ejector pins (6) are mounted at the front side of the guide block (3). The guide block (3) also has steps at both sides and this step is precisely guided inside the guide rails (7).
Fig.l 1 shows guide rails (7) which are mounted at both sides of the guide rail. This is mounted below the spacer (4). The guide block (3) is precisely guided in the gap between the step of the guide rail (7) and the spacer (4). This step in the guide rail (7) is also used for holding the guide block (3). The space/gap between the guide rails is precisely maintained and the guide rails are precisely located in their position with dowel pins and clamped to top plate (12) by alien screw (9d).
Fig. 12 shows spacer (4) which is a hardened plate mounted on to the top half of the bending tool. This is placed between the guide rails (7) and the top plate (12). This is used for maintaining the position of the ejector pin (6) in the vertical direction and is also used for providing a hardened guiding surface to the guide block (3). A pocket is provided on the spacer (4). This acts as a relief for the guide block (3). A provision for mounting a wear plate (11) inside the guide block (3) is also provided in the spacer (4).
Fig.13 shows a wear plate (11) which is a hardened member housed inside the pocket of the spacer (4). This is used for supporting the ejector cam (2) during downward

stroke. A small entry radius is provided at the bottom side of the front face of the wear plate (11) for smooth engagement of the ejector cam (2)with the wear plate(l 1).
Fig. 14 shows Sleeve is provided between guide block (3) and washer (9c). An alien screw (9d) is inserted through the sleeve (9b) and is clamped to the guide block (3). The length of the sleeve (9b) is maintained based on the stroke required for the ejector & length of spring. The sleeve (9b) ensures that the spring (9a) is not over tightened beyond the required length and force. A washer (9c) is provided between the alien screw (9d). The washer (9c) provided ensures proper resting surface for both Allen screw (9d) and sleeve (9b).
Fig. 15 shows clamping plate (8), which is mounted to the top plate (12) at the rear side of the bending cffe, behind the guide bfock (3). This is used for providing a resting surface and support to the spring (9a) during working. A hole provided in the clamping plate (8) is used for guiding the sleeve (9b) and alien screw (9d) during working.
Fig.16 shows the holder plate (5) which is clamped to the guide block (3). This is located precisely to the guide block by means of dowel pins. Provision for holding the ejector pins(6) are provided in the holder block. This holds the ejector pins (6) in position during working.
Fig. 17 shows ejector pins (6) which are hardened members which are mounted inside the holder plate (5). This is placed in position behind the bending punch (1) during the downward stroke. This moves forward along with the guide block (3) during the upward stroke. The length and stroke of the ejector pins (6) are decided based on the width of the workpiece (10) and the distance required pushing the workpiece (10) out of the bending punch (1). The ejector pin (6) actuates /moves the ejector block (15) up & down. The ejector pins (6)are directly connected to a bottom buffer (an

accessory of press, which houses springs in it) and transfers the spring (9a) load to the ejector block (15) during upward and downward stroke of the press.
C FRAME (16) is a hardened member used for housing the die block (14) & the ejector block (15). The C FRAMEs (16) are directly screwed & dowelled to the base plate (13). The gap between the two C FRAMEs is precisely maintained and die block (14) and the ejector blocks (15) are positioned and assembled in it as shown in figure 3.
Fig. 18 shows bending die in the upward stroke condition. In the upward stroke condition the spring (9a) is in the pre compressed condition and the ejector pins (6a) are in the forward stroke position. The guide block (3) is free from the ejector cam (2) engagement at this time. The ejector block (15) is pushed up by the ejector pin (6) from the bottom. The ejector block (15) comes to the same level of die block (14). The workpiece (10) is placed on the ejector block (15).
Fig. 19 illustrates a bending tool in the downward stroke. During the downward stroke of the press the ejector cam (2) engages with the guide block (3). The tapered surface of the guide block (3) gets engaged with the tapered surface of the ejector cam (2). The engagement of the tapered surface pushes the guide block (3) & moves it backward during downward stroke. Thus the ejector pin (6) gets cleared from the bending region of the bending punch (1). The compression spring (9a) is in the compressed state at this time.
Fig.20 illustrates a bending tool in the downward stroke with travel still pending. The guide block (3) is getting pushed backward and ejector cam (2) is engaged with the wear plate (11) in the spacer (4). The spring (9a) is getting compressed between clamping plate (8) and the guide block (3). The ejector pin (6) is taken backward during the downward stroke. Various related dimensions between elements are also shown in fig. 20.

Fig. 21 illustrates a bending tool in the downward stroke. During the downward stroke the punch (1) comes in contact with the workpiece (10) and holds it in the position. During the remaining downward stroke load is exerted on to the bottom half of the tool and the bending puch (1) pushes the workpiece (10), the ejector block (15) & the ejector pins (6) downward. Load is exerted on to the die blocks (14) on either side of the bending punch (1). This deforms the workpiece (10) against the bending punch (1) and bending is completed.
Fig. 22 illustrates a workpiece (10) with bending operation completed. At the end of the downward stroke, the bending is completed and the workpiece (10) clings to the bending punch (1). The bottom face of the ejector block (15) butts against the base plate (13) and the ejector pin (6) is pushed down below the base plate (13), exerting load onto the bottom buffer.
Fig.23 illustrates a bending tool in the fully downward stroke condition. The guide block (3) is fully moved backward. The straight surface of the ejector cam (2) is engaged with the guide block cavity. The spring (9a) is in the compressed condition. The ejector pin (6) and the holder plate (5) are taken behind the bending punch (1). The ejector pin (6) is positively taken behind the bending region in the bending punch (1). Various related dimensions between elements are also shown in fig. 21.
Figure 24 shows workpiece taken up by the bending punch. The same is pushed/ejected out by the ejector mechanism provided at the rear side of the tool.
ADVANTAGES OF THE INVENTION
1. The workpiece is taken out of the tool positively after every stroke
2. The construction takes care of safety to the operator
3. Ease of assembly and maintenance

4. The spring pressure can be adjusted according to the weight of the workpiece and the stroke also can be adjusted.
5. The arrangement is fully mechanical and ejection of the workpiece is automatic.
6. Doesn't require another operation to actuate the mechanism since the operation of the mechanism is fully dependant on the stroke of the press.
The invention has been described in a preferred form only and many variations may be made in the invention which will still be comprised within its spirit. The invention is not limited to the details cited above. The guide means, screw means, top and base prates, guide rafts, sleeves and holder plates as stated do not limit the scope of the present invention. The structure thus conceived is susceptible of numerous modifications and variations, all the details may furthermore be replaced with elements having technical equivalence. In practice the materials and dimensions may be any according to the requirements, which will still be comprised within its true spirit.

WE CLAIM
1. A bending die assembly having a unique ejection arrangement for automatic
ejection of a workpiece after each bending operation, said assembly comprising:
a movable top plate;
a fixed base plate located in proximity to said top plate and mechanically engaged to it by means of a support means which mechanically engages said top plate to the base plate, said top plate being movable along said support means in a vertical plane;
bending punch located in fixation to below front half of said top plate for bending the workpiece as desired;
guiding arrangement located in the rear half of said top plate, said guiding arrangement comprising plurality of guide rail means; guide block means having stepped profile so as to co-operate with said guide rails during bending operation, said guide block means being movable in substantially horizontal plane between said rail means; wherein sajd guide block means having tapered profile substantially at its center;
a cam means fixed to said base plate in a substantially vertical plane;
a spring assembly means operatively mounted on said guide 6/ock means at its rear portion so as to provide the guide block with a resilient to and fro motion;
an ejector assembly means comprising ejector members and ejector block means, said ejector members being operatively mounted on the rear side of the

said bending punch and said ejector block being fixed to the base plate in a substantial aligned position with the bending punch;
wherein said cam means having tapered profile substantially at the middle portion such that downward stroke of said top plate provides cooperative engagement between said tapered surfaces of the cam means and the guide block means thereby providing a substantial horizontal backward resilient motion of said guide block means upto a predetermined position so as to compress the said spring such that during upward stroke of the said top plate the tapered profile of the cam means provides a substantial horizontal forward resilient motion of said guide block means thereby actuating said ejector members in a manner that the workpiece is just ejected from the bending punch.
2. Assembly as claimed in claim 1 wherein said cam means comprising a wedge profile having tapering angle ranging between 18° and 25°.
3. Assembly as claimed in claims 1 and 2 wherein said cam means further comprising straight limb portions on both ends of tapered profile adapted to provide predetermined delay for the ejection.
4. Assembly as claimed in claim 1 wherein said spring assembly means comprising:
(i) compression spring;
(ii) a sleeve;
(iii) a washer; and
(iv) an alien screw.

5. Assembly as claimed in claim 4 wherein said compression spring is a light load spring having spring load such that it just pushes the workpiece out of the bending punch.
6. Assembly as claimed in claim 1 wherein said guide block having tapered profile ranging from 18° to 25°.
7. Assembly as claimed in claim I wherein said ejector member comprising pin means having appropriate length and stroke corresponding to the width of the workpiece and distance required to push the workpiece out of the bending punch.
8. Assembly as claimed in any of the preceding claims further comprising spacer means adapted to maintain position of the ejector pin in a substantially vertical direction and providing hardened surface to the guide block.
9. Assembly as claimed in any of the preceding claims further comprising holder plate means adapted to hold the ejector pins in position during working.
10. A bending die assembly having a unique ejection arrangement for automatic ejection of a workpiece after each bending operation as herein substantially described and illustrated with the accompanying drawings.