US2901023A

US2901023A - Tube bending die with flowable rubber pad to prevent collapse of the tube

Info

Publication number: US2901023A
Application number: US458293A
Authority: US
Inventors: Teitelman Herbert
Original assignee: Individual
Current assignee: Individual
Priority date: 1954-09-24
Filing date: 1954-09-24
Publication date: 1959-08-25
Anticipated expiration: 1976-08-25

Description

Aug. 25, 1959 H. TEITELMAN TUBE BENDING DIE WITH FLOWABLE RUBBER PAD TO PREVENT COLLAPSE OF THE TUBE Filed Sept. 24, 1954 IN V EN TOR.

l a! 72/2154 MAN 14 T TOIPNE Y5 BYWMMJ United States Patent TUBE BENDING DIE WITH FLOWABLE RUBBER PAD TO PREVENT COLLAPSE OF THE TUBE Herbert Teitelman, Waban, Mass.

Application September 24, 1954, Serial No. 458,293

9 Claims. (Cl. 153-48) (Granted under Title 35, US. Code (1952), sec. 266) The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

The present invention concerns a die and in particular concerns a pipe bending die having a resilient face.

It has been the practice in the past in bending pipe to provide a male die that along its bending edge is machined with precision. It has been customary to form such dies ofhigh quality steel.

One disadvantage of precision machined steel dies has been that these dies are exceedingly expensive because of the time and high cost involved in the precision machining of the bending face. Likewise there is loss of time in the pipe bending operation while awaiting manufacture of the precision machined die which manufacture involves the expenditure of a large amount of time.

A further disadvantage resides in the fact that once the precision machining operation has been performed, the metal die can bend only one radius of pipe and it is impossible with such a die to bend more than one radius. Furthermore, because of springback in the pipe that is bent it is necessary that compensations for such springback be made; the radius of the precision machine die is therefore carefully calculated to a smaller radius than the radius of the pipe following the springback. In order to bend different pipes to different radii, it is necessary to provide a plurality of dies of the proper radii.

The present invention overcomes these difficulties by providing a metal die having a resilient pad that forms the bending face. It is unnecessary to perform a precision machining operation and this reduces the time involved in making the die and also the cost of manufacture. Likewise, the die can easily be modified in a matter of minutes to bend a variety of different pipe radii by simply providing rubber shims appropriately at the center or ends or both of the bending surface.

Furthermore, it is a simple matter to compensate with the rubber faced die for the springback inherent in the pipe to be bent.

Further advantages in use of the die having the rubber bending surface arise from the fact that both the rubber and the material of the pipe being bent actually flow during bending which reduces gathers on the inside of the pipe bend and likewise reduces thinning and flatten ing on the outside of the pipe bend.

An object of the invention is to provide a die.

Another object is to provide a pipe bending die having a resilient bending face.

Another object is to provide a pipe bending die having a rubber bending face.

Another object is to provide a pipe bending die that is inexpensive to manufacture, that involves a minimum of time during manufacture, and that completely eliminates the need for precision machining.

O ther objects and many of the attendant advantages of this invention will be readily appreciated as the same ice 2 becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

Fig. 1 is a perspective view of a preferred embodiment of the invention,

Fig. 2 is a top plan view of the preferred embodiment,

Fig. 3 is an end elevation of Fig. 2,

Fig. 4 is a vertical sectional View taken on lines 44 of Fig. 2 omitting certain parts and in addition showing the diein operation, and v Fig. 5 is a view of shim for varying the curvature of the die. 7 p

In the drawings there is shown a pipe bending die 10 comprising a top plate 11 and a bottom plate 12 which are separated by a spacer 13 extending completely along the substantially straight rear edges of plates 11, 12. The forward edges 11a, 12a of plates 11, 12 are arcuate. Top plate '11, bottom plate 12 and spacer 13 are welded together to form an integral unit and

blocks

14, 15 are welded across the sides of top plates 11, 12 to partly close the space formed between plates 11, 12. An opening 16 is formed centrally at the rear of spacer 13 to accommodate a fitting for mounting the die 10 in a pipe bending machine 17, one type of which is shown in US. Patent No. 2,382,266 issued to G. N. Simonsen on August 14, 1945.

The space formed between plates -11, 12 is substantially filled by "a rubber pad 18 having an arcuate bending sur face 19. Top plate 11 together with bottom plate 12 and rubber pad 18 are formed with their forward edges arcuate and with the forward edges of top plate 11 and bottom plate 12 slightly overhanging the arcuate bending surface 19 of pad 18 to form a convex groove the bottom of which is defined by bending surface '19 of pad .18.

The arcuate forward edges of top plate 11 and bottom plate 12 are rough cut and it is unnecessary that they be precision machined. As shown in the preferred embodiment the arcuate forward edges of top plate 11 and bottom plate 12 together with bending surface 19 of pad 18 cover an arc of less than of about 10 inch radius. Obviously the die can be made to cover an are 90 or larger and a radius that is larger or smaller than 10 inches.

Bolts

22 and 23 extend upwardly from bottom plate 12 through rubber pad 18 and top plate 12.

Nuts

24, 25 are tightened in such manner that the spacing of forward arcuate edges 11a, 12a of plates 11, 12 is maintained constant under all conditions of stress.

Footpads

31, 32 are provided on bottom plate 12 and footpads 33, 34 are provided on top plate 11. In operation, the die can be inverted from the position shown in Fig. 1 and rest upon footpads 33, 34. Such inversion in use provides uniform wear and preserves the length of the die.

In operation the die is mounted upon a suitable machine with a pipe 21 to be bent in front of rubber bending surface 19 with the ends of the pipe at each side of the die being restrained. The die is moved forward toward the observer as seen in Fig. 1, to cause bending of the pipe.

Due to the rigid mounting of top plate 11 with respect to bottom plate 12, it is thought impossible for the rubber to flow in an up and down direction as seen in Fig. 1' but during the bending operation when the pipe 21 is bent over the resilient fiowable rubber convex die the pressure of the pipe on the rubber will result in an indentation of the pipe laterally of itself into the rubber, with some of the rubber along the sides of the indentation deformed outwardly along the sides of the pipe as shown in Fig. 4

able or flowable when displaced by its deformation resulting from the rubber pressing against the pipe. It is thought that because of the flow of rubber along exposed bending surface or face 19 and because of the uniform flow of metal in the pipe being bent, the outside of the pipe during bending undergoes uniform flow of metal; it is definitely established that there is uniform thinning of the outer surface of the bent pipe which completely elimia smaller radius is provided. Similarly by use of suitable shims compensation is easily provided for springback of the pipe after being bent regardless of the degree the particular pipe springs back.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

I claim:

1. A pipe bending die comprising a casing having a chamber therein with an open edge and otherwise closed, and a body of elastic and incompressible but deformable material confined snugly in said chamber and having its exposed surface at said open edge of the chamber of convexly arcuate shape corresponding to the curvature of a bend to be placed in said pipe, and over which a pipe may be bent when the part of the pipe to be bent is disposed lengthwise of itself along the curvature of said arcuate surface, whereby the pipe when said arcuate surface is pressed against it will indent itself somewhat into said body and displace by deformation some of the elastic body sidewise up along the sides of the pipe where it resists sidewise deformation of the pipe at the bend during the bending.

2. A pipe bending die comprising a flat top plate having a convexly arcuate forward edge, a back edge, and end edges, a flat bottom plate having the same configuration as the top plate disposed in spaced relation from the top plate and in registration therewith, a spacer extending between the top plate and the bottom plate along the back and end edges thereof and integral therewith, said plates and spacer defining a space therebetween open solely along said arcuate edge, and a resilient rubber pad confined in said space and having a substantially straight back edge resting against the forward edge of said spacer, said pad of elastic, incompressible but deformable material having a convexly arcuate exposed forward surface over which a pipe may be bent, whereby the pipe will be indented into the pad and displace by deformation some of the elastic material sidewise up along the sides of the pipe where it resists sidewise deformation of the pipe at the bend during the bending.

3. A pipe bending die comprising a flat top plate having a substantially straight rear end and a convexly arcuate forward edge, a flat bottom plate having the same configuration as the top plate disposed in spaced relation from the top plate and in registration therewith, a spacer plate extending between the top plate and the bottom plate along the back edges thereof and united therewith, said plates and spacer defining a space there between, a pair of end blocks extending across part of the space one block at each side of said plates, a resilient rubber pad confined in said space and having a substantially straight back edge resting against the forward edge of said spacer, said pad having a convexly arcuate exposed forward edge opposite from said straight back edge and over which pipes may be bent, a pair of bolts extending upwardly from said bottom plate through said pad and top plate, anda pair of nuts one on each of said bolts, to lock said top plate and said bottom plate against spreading when the rubber between the plates is compressed by bending a pipe thereover.

4. A pipe bending die comprising a fiat top plate having a substantially straight rear end and a convexly arcuate forward edge, a flat bottom plate having the same configuration as the top plate disposed in spaced relation from the top plate and in registration therewith, a spacer extending between the top plate and the bottom plate along the bacl; edges thereof and united therewith, said plates and spacer defining a space there between open along the arcuate forward edge, a pair of end blocks extending across and partially closing part of the space, one block at each side of said plates, and a resilient rubber pad confined in said space and having a substantially straight back edge resting against the forward edge of said spacer, said pad having an exposed convexly arcuate forward edge over which a pipe may be mechanically bent.

5. A pipe bending die comprising a flat top plate having a substantially straight rear end and a convexly arcuate forward edge, a flat bottom plate having a similar configuration as the top plate disposed in spaced relation from the top plate and in registration therewith, a spacer extending between the top plate and the bottom plate along the back edges thereof and integral therewith, said plates and spacer defining a space there between, a pair of end blocks extending across part of the space one block at each end of said plates, and a resilient rubber pad dis posed in and filling said space and having substantially straight back edge resting against the forward edge of said spacer and abutting the end blocks, said pad having an exposed, convexly arcuate forward edge, said pad being arranged with the forward edges of said top plate and said bottom plate slightly overhanging the forward edge of said pad to provide a convex groove the bottom of which is formed by the forward edge of said pad.

6. A pipe bending die comprising a flat top plate having a substantially straight rear end and a convexly arcuate forward edge, a flat bottom plate having a similar configuration as the top plate, disposed in spaced relation from the top plate and in registration therewith, a spacer extending between the top plate and the bottom plate along the back edges thereof and integral therewith, said plates and spacer defining a space there between, a pair of end blocks extending across part of the space one block at each side of said plates, a resilient rubber pad disposed in and largely filling said space and having a substantially straight back edge resting against the forward edge of said spacer and ends abutting said blocks, said pad having an exposed, convexly arcuate forward edge, said pad being arranged with the forward edges of said top plate and said bottom plate slightly overhanging the forward edge of said pad to provide a convex groove the bottom of which is formed by the forward edge of said pad, a pair of bolts extending upwardly from said bottom plate through saidipad and top plate, and a pair of nuts one on each of said bolts, to lock said top plate and said bottom plate against spreading.

7. A device for use in bending hollow pipe about an axis that extends laterally of the pipe length, which comprises a form having therein a cavity with an open face and otherwise closed, an elastic body having the properties of elastic flowable rubber confined in said cavity with a pipe bending face exposed through said open form face, said elastic body having its said exposed face convexly arcuate and of a curvature along the are approximately equal to that desired to be formed in said hollow pipe that is bent thereover, whereby when said arcuate bending face of said body is disposed lengthwise along a hollow pipe and pressed thereagainst with a force sufiicient to bend the pipe to conform to said convex curvature, the exposed face of said elastic body will be indented by said pipe and flow somewhat along the transverse periphery of the pipe and resist flattening of the pipe at the arcuate bend placed therein.

8. The device as set forth in claim 7, wherein the opposite sides of said form which define the sides of the open face of said cavity extend a substantial distance outwardly beyond and clear of the arcuate face of said elastic body, suflicient, when the arcuate bending face of said elastic body is indented by a pipe being bent thereover, to aid in pressing the deformed body along the indentation against the sides of the pipe at the bend.

9. The method of bending a tubular pipe of bendable material, while the pipe at the bend retains its original cross-sectional shape, which comprises pressing against that portion of the pipe where a bend is to be formed an exposed =arcuate convex surface of an otherwise confined body of elastic, incompressible, but deformable material, with the pipe extending lengthwise of itself along said arcuate surface and with sufficient force to cause said pipe to conform to the curvature of said arcuate surface, whereby the pressure of the arcuate surface of said elastic body against said pipe will indent the pipe into said body and displace by. deformation some of the elastic body up along the sides of the pipe and resist sidewise deformation of the pipe at the bend during the bending.

References Cited in the file of this patent UNITED STATES PATENTS 447,295 Brenner Mar. 3, 1891 1,267,591 Rehbein May 28, 1918 1,268,360 Kimball June 4, 1918 1,743,100 Blackburn Jan. 14, 1930 2,055,077 Guerin Sept. 22, 1936 2,303,059 Misfeldt Nov. 24, 1942 2,382,266 Simonsen Aug. 14, 1945 2,397,608 Johnson Apr. 2, 1946 2,799,317 Toulmin July 16, 1957 FOREIGN PATENTS 1,743,100 Great Britain Jan. 14, 1930 417,656 Great Britain Oct. 3, 1934