DESC:FIELD OF INVENTION

The present invention relates to a device for forming operations of sheet metal components during automobile manufacturing. In particular, the invention relates to cushion pins used in cushion units of sheet metal pressing machines. More particularly, the invention relates to hollow cushion pins with externally grooved profiles for use in of sheet metal pressing machines for manufacturing profiled sheet metal pressed components.

BACKGROUND OF THE INVENTION

In modern automotive manufacturing plant, sheet metal is widely used for manufacturing a variety of pressed components. So, different press machines and a variety of dies are used for making of such sheet metal components. The dies for performing draw, deep draw and forming operations primarily consist of three parts: cavity, punch and blank holder. For performing any forming operation, the blank is first held between the blank holder plate and the cavity and then it is pressed by means of the press machine against the punch by applying pressure using the cushioning force.

For forming and/or drawing operation, a cushion unit is also provided on the press machine and the blank holder cushion pins are used for carrying out this operation. These cushion pins are solid, cylindrical bars of different diameters and various lengths. The sheet metal pressing operation is incomplete without oil, because oil is required for lubrication, cooling and preventing the rusting of the sheet metal used for making pressed components therefrom. Also, during the application of oil on sheet metals for smooth material flow of the sheet metal, it tends to percolate on the surface of the die, press machine and on cushion pins as well.

DISADVANTAGES WITH THE PRIOR ART

The use of such solid conventional cushion pins of cylindrical shapes leads to following disadvantages:
? Cushion pins are quite heavy.

? Cushion pins are slippery, since oil present on metal sheets drips on them.

? Heavy cushion pin complicates its removal and placement in the subsequent operational position.

? After each set-up, the cushion pins have to be relocated to new positions according to the layout of the new die.

? Frequent mistakes occur because this creates fatigue and relocating the cushion pins is a cumbersome activity.

? Cushion pins are prone to slip from the operator’s hands and to fall down, thereby causing injury to operator’s feet.

Therefore, there is an existing need for improving the construction of the cushion pins to overcome the difficulties faced due to the current design of the conventional solid, cylindrical cushion pins and thus to eliminate the abovementioned disadvantages associated with the existing cushion pins.

OBJECTS OF THE INVENTION

Some of the objects of the present invention - satisfied by at least one embodiment of the present invention - are as follows:

An object of the present invention is to provide cushion pins used for making sheet metal components, which are light-weight.

Another object of the present invention is to provide cushion pins which do not slip from operator’s hands and safe from falling down on operator’s feet during the manufacture of the sheet metal components.

Still another object of the present invention is to provide cushion pins which are easy to be removed and relocated to new position on the same or new die for making sheet metal components.
Yet another object of the present invention is to provide cushion pins which avoids operator’s mistakes during drawing and/or forming operations for making sheet metal components.

A further object of the present invention is to provide cushion pins which reduce the operator’s fatigue and facilitates ease of carrying out forming/drawing operation for making sheet metal components.
.
These and other objects and advantages of the present invention will become more apparent from the following description when read with the accompanying figures of drawing, which are, however, not intended to limit the scope of the present invention in any way.

SUMMARY OF THE INVENTION

In accordance with the present invention, there is provided a cushion pin for performing forming operations on sheet metal presses, wherein the cushion pin comprises:

• a hollow sleeve;
• a plurality of profiled grooves partially configured on the outer diameter thereof;
• the ends of the hollow sleeve are configured free from grooves;

wherein the grooves are configured narrower than average operator finger thickness and have a depth of about 2 mm.

Typically, the grooves have a trapezoidal profile.

Typically, the grooves have a straight profile.

Typically, grooves have a curved profile.

Typically, the bases of the grooves are knurled for providing a better grip to the operator.
Typically, at least five number of grooves are configured on the cushion pin.

Typically, the lengths of the groove-free ends of the hollow sleeve are equal.

Typically, the lengths of the groove-free ends of the hollow sleeve are different.

Typically, the outer ends of the hollow sleeve are configured rounded.

In accordance with the present invention, there is also provided a cushion pin for performing forming operations on sheet metal presses, the cushion pin comprises:

• a hollow sleeve having its outer diameter and inner diameter in a ratio of about D:d = 1:0.55D;
• a plurality of profiled grooves partially configured on the outer diameter thereof; the pitch of the grooves about 15 mm and the depth of the grooves about 2 mm;
• the ends of the hollow sleeve are configured free from grooves; the distance of groove-free ends about 50 mm from the outer ends thereof;

wherein at least five number of grooves are configured on the hollow sleeve depending on the height of the cushion pin above the bolster plate, the grooves bases are provided with knurling for providing a better grip to the operator.

SOLUTION OFFERED BY THE PRESENT INVENTION

In accordance with the present invention, it is proposed to provide hollow cushion pins with grooves on the outer surface thereof, which can be easily used in press machines employed during manufacture of the sheet metal components, particularly automotive sheet metal components. The cushion pins configured according to the present invention are simple in design and safe to be used by the machine operators, however achieve the same results like the conventional solid, cylindrical cushion pins.
This novel cushion pin design is developed in-house, installed successfully and offers a low-cost solution to the drawbacks with the conventional cushion pins described above.

The cushion pins manufactured according to the present invention have the following characteristic features:

• Universal design, which can be easily adopted / installed in any type of automated or stand-alone sheet metal press-line operation.

• Cushion pin is drilled in the center by maintaining the ratio of outer to inner diameter approximately in a range of 1: 0.55D.

• Grooves on the outer diameter of the cushion pin are made at a pitch of about 15 mm and with a depth of about 2 mm.

• Grooves are provided only at the distance of about 50 mm from the ends thereof.

• Number of Grooves on cushion pins can be selected as per the application (as shown in figures) e.g. on full length, half-length or only 4 to 5 grooves to be used as per the cushion pin-height above the bolster.

• Knurling is possible only on the groove surface.

• Eliminates operator’s fatigue, since the cushion pin-weight reduces by almost 33% of the conventional pin-weight, so handling is much easier.

• Eliminates any chance accidents caused by cushion pin slippage from operator’s hands.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

The present invention will be briefly described with reference to the accompanying drawings, which include:

Figure 1 shows a schematic diagram of the pressing machine used for pressing of sheet metal components using the dies and punches. Here, the machine is in a position before operating the cushion unit provided therein.
Figure 2 shows a schematic diagram of the pressing machine used for pressing of sheet metal components using the dies and punches. Here, the machine is in a position after operating the cushion unit provided therein.

Figure 3a shows a cross-sectional view of the first embodiment of the cushion pin configured in accordance with the present invention.

Figure 3b shows a front view of the second embodiment of the cushion pin configured in accordance with the present invention.

Figure 3c shows a front view of the third embodiment of the cushion pin configured in accordance with the present invention.

Figure 4a shows a cross-sectional view of the fourth embodiment of the cushion pin configured in accordance with the present invention.

Figure 4b shows a front view of the fourth embodiment shown in Figure 4a.

Figure 4c shows a front view of the fifth embodiment of the cushion pin configured in accordance with the present invention.

Figure 4d shows a front view of the sixth embodiment of the cushion pin configured in accordance with the present invention.

Figure 4e shows a front view of the seventh embodiment of the cushion pin configured in accordance with the present invention.

DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS

In the following, different embodiments of the present invention will be described in more details with reference to the accompanying drawings without limiting the scope and ambit of the present invention in any way.

Figure 1 shows a schematic diagram of the pressing machine 10 equipped with press crown and motor 12, which is used for pressing of sheet metal 14 for manufacturing profiled sheet metal pressed components using the dies 15 (not shown) and punches 16. Here, the machine is in a position before operating the cushion unit provided therein. The machine 10 includes a press slide 18, an upper tool 20, a lower tool 22, a blank holder 24, and a bolster plate 26 supported on a cushion pin plate 28. The bolster plate 26 accommodates a plurality of cushion pins 100 in accordance with the present invention. The cushion pin plate 28 can be raised or lowered by means of a cushion cylinder and piston assembly 30 provided under the press bed 32.

Figure 2 shows a schematic diagram of the pressing machine 10 used for pressing of sheet metal components using the dies 15 and punches 16. Here, the machine is in a position after operating the cushion unit provided therein.

Figure 3a shows a cross-sectional view of the first embodiment of the cushion pin 100 configured in accordance with the present invention. It has a length L, outer diameter D and bore therethrough has a diameter d. It includes a plurality of profiled grooves Gr, which help in better grip to the operator during removal and relocation thereof, while changing the dies or reset-up thereof. This significantly enhances the operator’s safety. Normally, grooves Gr are provided in the middle portion of the cushion pin 100 and both ends thereof have a length l1 and l2 free from any groove. The lengths l1 and l2 in this embodiment are same (l). However, they can also be configured different, as discussed in the following. The grooves Gr have a depth t1 from the surface thereof. Further, the lengths of the lands and valleys of the grooves Gr are l3 and l4 respectively. In this embodiment, the grooves Gr have a tapered profile on both sides thereof.

Figure 3b shows a cross-sectional view of the second embodiment 110 of the cushion pin configured in accordance with the present invention. However, no grooves Gr are provided on the first half-length l6 of the cushion pin 110 and the other end half-length also does not have any groove Gr for length l5 from this other end. The profile of the grooves Gr in this embodiment is similar to that shown in Figure 1.

Figure 3c shows a front view of the third embodiment 120 of the cushion pin configured in accordance with the present invention. Here, the sides of the grooves Gr have a curved profile and their flat base surfaces Kn have been suitably knurled for better gripping. Both the ends of the cushion pin 120 do not have any groove Gr for length l5 thereof.

Figure 4a shows a cross-sectional view of the fourth embodiment 200 of the cushion pin configured in accordance with the present invention. In this embodiment, a plurality of grooves Gr are provided, except for two ends of the cushion pin 200 having length L, outer diameter D and through bore of diameter d. The cushion pin 200 has no groove at both ends thereof each having a length l. The grooves Gr have a depth t2 from the surface thereof. Further, the lengths of the lands and valleys of the grooves Gr are l7 and l8 respectively. In this embodiment, the grooves Gr have a rectangular profile.

Figure 4b shows a front view of the fourth embodiment 200 of the cushion pin shown in Figure 4a.

Figure 4c shows a front view of the fifth embodiment 210 of the cushion pin configured in accordance with the present invention. Here, the first end of the cushion pin 210 has a length l and the second end has a length l9. The profile of the grooves Gr is same as in Figure 4a. However, the grooves extend over just half the length L of the cushion pin 210.

Figure 4d shows a front view of the sixth embodiment 220 of the cushion pin configured in accordance with the present invention. Here, the first end of the cushion pin 220 has a length l and just 4 or 5 grooves Gr are provided out of the length L of the cushion pin 220.

Figure 4e shows a front view of the seventh embodiment 230 of the cushion pin configured similar to the one shown in Figure 4a; however, the flat base surfaces Kn of the grooves Gr have been suitably knurled for better gripping.

DESCRIPTION OF THE PRESENT INVENTION

On studying the cushion pins available on cushion units of the sheet metal pressing machines of different manufacturers (OEMS), it was observed that all cushion pins used until now are heavy and slippery and therefore, pose serious safety concerns for the operators, if they fall down from the hands of the operators due to oil sticking on them. The present inventive concept of having a hollow cushion pin with different types and lengths of grooves for better hold is quite unique in nature, which avoids the disadvantages associated with the conventional solid, cylindrical and thus heavy cushion pins. This weight reduction of the cushion pins leads to substantial cost savings for the overall cushion unit as well. Cushion pins with lower diameters than holes size of the press machines are in use, but the cut-pieces generated from dies fall from the gap of the pin and holes. These cut-pieces act as packing below the cushion pins, which also causes major quality concerns.

In all, there are about 120 nos. of holes for cushion pins on a press machine 10 of bed size of 2.5 to 4.5 meter. Some die manufacturers design their dies with increased height, which can accommodate all cushion pins therein, duly placed on bolster plates. However, this increases the size and height of dies by almost 30 to 40%, which also leads to increased die manufacturing cost. The solution proposed and successfully implemented within the scope of the present invention is first of its kind and is a low-cost and user friendly solution.

During press production, the cushion pins are placed in bolster plates 26 as per the layout of parts and are put in the holes present on the bolster plates 26 and these cushion pins rest on cushion pin plate 28. These cushion pins are required for operating the blank holder 24. Once charged, the cushion pins push the cushion pin plate 28 and the cushion pins resting on the cushion pin plate lift-up the blank holder 24 plate. During pressing operation, the press slide 18 presses the upper tool 20, the metal sheet 14 placed between the die cavity 15 and blank holder 24 is pressed against the punch 16 and the desired shape of the sheet metal components is obtained.

The rate of material flow depends on the pressure applied. The height of cushion pins plays an important role for maintaining all around uniform pressure on the blank holder 24, so as to avoid any variation in the length, for which the OEMs normally use solid cushion pins.

However, by replacing the conventional solid, cylindrical cushion pins by the hollow externally grooved cushion pins of different configurations in accordance with the present invention explained above, the same quality of sheet metal pressed components could be achieved with substantially lower material use and by providing significantly enhanced safety to the operator.

The preferred embodiment of the cushion pin with 5 external grooves has given significantly improved results over a considerable period of time. However, all the cushion pin embodiments described above have fully satisfied the operational requirements of low-weight and anti-slip design, since holding the cushion pin in position for its placement and removal, even 4 to 5 grooves are sufficient. This also reduces the manufacturing cost thereof. Because, forming grooves on the entire length of the cushion pins increases the cost of machining. However, wherever applicable, by providing increased number of grooves helps in further reducing the cushion pin weight.

The typical groove width selected is just 15 mm. Because, average width of operator fingers is 16 to 20 mm, and while holding the object (cushion pin), the central portion of finger surface comes in contact with the grooves for gripping the object. Thus, the width of 15 mm was calculated and tested to be most suitable. Similarly, the optimum groove depth of 2 mm is selected. Any further increase in groove depth will decrease the wall thickness of the cushion pin, which may lead to cracking of the cushion pin. The cushion pins are also preferably provided with rounded edges, which substantially facilitates in handling of the cushion pins by the machine operators.

TECHNICAL ADVANTAGES AND ECONOMIC SIGNIFICANCE

The hollow cushion pins with grooves on their outer surface configured in accordance with the present invention have the following advantages:

? Simple, cost effective solution with huge scope of horizontal deployment across the industry.

? Eliminates Operator accident by eliminating pin slippage issue.
? Weight reduction of pin reduces fatigue hence reduces the die loading time by 7 mins.

? Material requirement for making this cushion pins reduces by 33%.

? On some presses the length of pins is about 800 mm and diameter is 50 to 60 mm the weight 12 to 15 kg ant it becomes cumbersome to change 80 to 100 pins for a larger press like 2000 Tons for every setup this method reduces weight by 33%

The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments.

The embodiments herein and the various features and advantageous details thereof are explained with reference to the non-limiting embodiments in the following description. The description provided herein is purely by way of example and illustration. The various features and advantageous details are explained with reference to this non-limiting embodiment in the above description in accordance with the present invention. The descriptions of well-known components and manufacturing and processing techniques are consciously omitted in this specification, so as not to unnecessarily obscure the specification.

It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, the skilled person will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments described herein and can easily make innumerable changes, variations, modifications, alterations and/or integrations in terms of materials and method used to configure, manufacture and assemble various constituents, components, subassemblies, assemblies and in terms of the size, shapes, orientations and interrelationships without departing from the scope and spirit of the present invention. It is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation.

The numerical values given of various physical parameters, dimensions and quantities are only approximate values and it is envisaged that the values higher or lower than the numerical value assigned to the physical parameters, dimensions and quantities fall within the scope of the disclosure unless there is a statement in the specification to the contrary.

Throughout this specification the word “comprise”, or variations such as “comprises” or “comprising”, shall be understood to implies including a described element, integer or method step, or group of elements, integers or method steps, however, does not imply excluding any other element, integer or step, or group of elements, integers or method steps.

The use of the expression “a”, “at least” or “at least one” shall imply using one or more elements or ingredients or quantities, as used in the embodiment of the disclosure in order to achieve one or more of the intended objects or results of the present invention. ,CLAIMS:We claim:

1. Cushion pin for performing forming operations on sheet metal presses, the cushion pin comprises:

• a hollow sleeve;
• a plurality of profiled grooves partially configured on the outer diameter thereof;
• the ends of the hollow sleeve are configured free from grooves;

wherein the grooves are configured narrower than average operator finger thickness and have a depth of about 2 mm.

2. Cushion pin as claimed in claim 1, wherein the grooves have a trapezoidal profile.

3. Cushion pin as claimed in claim 1, wherein the grooves have a straight profile.

4. Cushion pin as claimed in claim 1, wherein the grooves have a curved profile.

5. Cushion pin as claimed in anyone of the claims 1 to 4, wherein the bases of the grooves are knurled for providing a better grip to the operator.

6. Cushion pin as claimed in claim 1, wherein at least five number of grooves are configured on the cushion pin.

7. Cushion pin as claimed in claim 1, wherein the lengths of the groove-free ends of the hollow sleeve are equal.

8. Cushion pin as claimed in claim 1, wherein the lengths of the groove-free ends of the hollow sleeve are different.

9. Cushion pin as claimed in anyone of the claims 1 to 9, wherein the outer ends of the hollow sleeve are configured rounded.
10. Cushion pin for performing forming operations on sheet metal presses, the cushion pin comprises:

• a hollow sleeve having its outer diameter and inner diameter in a ratio of about D:d = 1:0.55D;
• a plurality of profiled grooves partially configured on the outer diameter thereof; the pitch of the grooves about 15 mm and the depth of the grooves about 2 mm;
• the ends of the hollow sleeve are configured free from grooves; the distance of groove-free ends about 50 mm from the outer ends thereof;

wherein at least five number of grooves are configured on the hollow sleeve depending on the height of the cushion pin above the bolster plate, the grooves bases are provided with knurling for providing a better grip to the operator.

Dated: this day of 28th September,2015. SANJAY KESHARWANI
APPLICANT’S PATENT AGENT