US3657911A

US3657911A - Bending machine

Info

Publication number: US3657911A
Application number: US19172A
Authority: US
Inventors: Kenneth W Clarke; Donald L Kinnsch; Archibald R Mcclay
Original assignee: Foster Wheeler Inc
Current assignee: Foster Wheeler Inc
Priority date: 1970-03-13
Filing date: 1970-03-13
Publication date: 1972-04-25
Anticipated expiration: 1989-04-25
Also published as: GB1342764A; JPS5342746B1; CA946271A

Abstract

A bending machine which bends tubes in both directions and which can form bends of different radii. A bending die assembly has two bending hubs, each with an axis of rotation, so that when the tube is to be bent in one direction the die unit turns about one axis and when the tube is to be bent in the other direction the die head turns about the other axis, the assembly being replaceable by another having bending hubs of a different radius to form bends of a corresponding radius in a tube.

Description

United States Patent Clarke et al.

[54] BENDIN G MACHINE [72] Inventors: Kenneth W. Clarke, Arcadia; Donald L.

Kinnsch, Los Alimitos; Archibald R. Mc- Clay, Costa Mesa, all of Calif.

Foster Wheeler Corporation, Livingston, NJ.

22 Filedz Mar. 13, 1970 [21] Appl.No.: 19,172

[73] Assignee:

[52] U. S.Cl ..72/157,72/306, 72/321 [51] Int. Cl t ..B2ld 7/04 [58] Field ofSearc h ..72/153,157,2l7,306,310,

[56] References Cited UNITED STATES PATENTS Kritzer, .lr ..72/306 Armstrong et al. ..72/217 Payne ..72/217 [451 Apr. 25, 1972 2,033,423 3/1936 Frank ..72/217 1,546,147 7/1925 Skinner..... ....72/217 1,624,804 4/1927 Robinson ..72/157 2,474,276 6/1949 Payne ..72/153 Primary Examiner-Charles W. Lanham Assistant Examiner-Michael J. Keenan Attorney-John Maier, 111, Marvin A. Naigur and John E. Wilson 57 ABSTRACT A bending machine which bends tubes in both directions and which can form bends of different radii. A bending die assembly has two bending hubs, each with an axis of rotation, so that when the tube is to be bent in one direction the die unit turns about one axis and when the tube is to be bent in the other direction the die head turns about the other axis, the assembly being replaceable by another having bending hubs of a different radius to form bends of a corresponding radius in a tube.

7 Claims, 7 Drawing Figures PATENTEU APR 2 5 1972 SHEET 10F 3 I INVljNlURS KENNETH W. CLARKE DONALD L.IUNNSCH ARCH/BALD R. MCCLAY AT TORNE Y PATENTEUAPR 2 5 m2 sum 3 UF 3 INVENTORS.

KENNETH W. CLARKE DONALD L. KINNSCH ARCHIBALD R. McCLAY we. W

AT TORNE Y 1 BENDING MACHINE BACKGROUND OF THE INVENTION There are many instances in industry where tubing must be bent in several directions over its length. An example is found in the boiler making industry where water tubes must be bent into a serpentine configuration to be used as components in the panels which are placed in the furnace area to convey water into the furnace area and to carryout the steam which is formed in them. Economizers and superheaters are also usually formed by bending tubes into serpentine configurations. In these cases, it is also necessary to bend each tube in both directions several times over its length.

In the past, equipment has been designed to carry out such bending operations but it has been somewhat inflexible in that it has only been able to form tube configurations having bends of one given radius. In the manufacture of furnace panels, economizers, superheaters and other components for boilers, different boilers will require different sized components so that it is desirable to have an apparatus which can be used to bend tubes so that the final configuration can have bends with a radius suitable for the boiler in which the component will be used. Undoubtedly, there are many other applications in industry where tubes, especially heavy tubes, must be bent in both directions to form a predetermined serpentine configuration, and where it is desirable that apparatus be available to provide for the manufacture of such configurations having different radii of bend.

SUMMARY It is the object of the present invention to overcome drawbacks found in the prior art, such as those set forth above. Accordingly, the present invention provides a bending machine having an interchangeable bending die assembly with two bending surfaces, each of which has its own axis about which the assembly may be rotated to bend the tube in a particular direction, the radius of bends formed in the tube being changeable by using die assemblies having different distances between the two axes and bending surfaces of different radii of curvature.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a fragmentary side view partly in section showing a bending machine according to the preferred embodiment of the present invention;

FIG. 2 is a fragmentary plan view of the bending machine of FIG. 1;

FIG. 3 is a front view partly in section of the bending die assembly shown in FIGS. 1 and 2 but in an enlarged scale;

FIG. 4 is a plan view of the lower die of the die assembly shown in FIG. 3;

FIG. 5 is a fragmentary plan view with parts broken away showing a portion of the machine shown in FIG. 1;

FIG. 6 is a front elevation of the same; and

FIG. 7 is a front view partly in section showing die heads for forming a tube configuration having radii of bend different from one formed by the die heads shown in FIGS. 1, 3 and 4.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A bending machine 10 which is shown in FIG. 1 has a frame 12 with a U-shaped section 14 open at the front end thereof and with a rear leg 16 and two forwardly projecting

legs

18 and 20. The lowermost leg 20 has secured to it a downwardly projecting bracket 22 which supports two parallel

hydraulic cylinders

24 and 26. The

cylinders

24 and 26 rotate a plurality of sprockets 30 which are secured for rotation about a common shaft 32 by operating on the opposite sides of a pinion gear through racks which are secured to each of the piston rods of the cylinders. The pinion is secured to the lower end of the shaft 32 to which the sprockets 16 are secured. The pinion and rack arrangement is more or less conventional and therefore not shown in detail.

The shaft 32 is split into a lower portion and an upper portion which are separated by a clutch mechanism 34, which has an upper disc 36 secured to the bottom of the upper portion of the shaft 32 and a lower disc 38 secured to the lower portion thereof, each of the

discs

36 and 38 having a longitudinally ex tending slot in which a key 40 can fit when the slots are vertically aligned. The key is always connected with the upper disc 36 and can be pushed into the slot in the lower disc 38 to lock the

discs

36 and 38 together by means of a hydraulic cylinder 42 which operates when the slot in the disc 38 is in the vicinity of that cylinder. The key is removed by a hydraulic cylinder 44 which acts on a horizontally extending rod (not shown) which moves the key 40 to the right and out of engagement with the slot. The clutch mechanism 34 permits the

cylinders

24 and 26 to rotate the upper portion of the shaft 32 as many rotations in one direction as desired. If it were: not for the clutching mechanism 34, the

hydraulic cylinders

24 and 26 could rotate the shaft 32 only until they reach the end of their stroke or until their respective rack gears no longer had teeth in mesh with the pinion.

As pointed out above, the plurality of sprockets 30 is mounted on the upper portion of the split shaft 32. Each of the sprockets 30 meshes with a chain 44, which in turn meshes with one of a plurality of sprockets 46 secured on a vertical shaft 48 which extends parallel to the shaft 32. The shaft 48 passes through bearings which are mounted in a vertical member 50 of the frame 12.

Mounted on the upper end of the shaft 48 is a support block 52, which when the shaft 48 is rotatedl by the

hydraulic cylinders

24 and 26 through the chains 44 and

sprockets

30 and 46, will rotate with the shaft 48. In the upper surface of the support block 52 is a groove 58, and engaged within the groove 58 is a slide block 60 which forms the base of a bending die assembly 62.

The bending die assembly 62 as shown in FIGS. 1 and 3 has an upper die block 64 and a lower die block 66. The lower die block 66, which is shown by itself in FIG. 4, has a left bending hub 68 and a right bending hub 70, each bending hub being surrounded over most of its circumference by a groove. Thus, the left bending hub 68 has a groove 72 which opens upwardly and outwardly. The groove 72 extends from the rear portion of the hub about the axis of the hub to a straight hole 74, which extends between the

bending hubs

68 and 70 from the rear of the lower die block 66 to the front thereof. In a like manner, the right bending hub 70 has. an upwardly and outwardly opening groove 76, which is symmetrical with respect to the groove 72 so that both grooves are joined in the straight hole 74.

The upper die 64 has a left bending hub which is surrounded over most of its circumference by a downwardly and outwardly opening groove 82 and a right bending hub 84 with a downwardly opening groove 86. The groove 82 overlies the groove 72 over their respective lengths while the groove 86 overlies the groove 76 over their respective lengths. In this manner, the

grooves

72, 76, 82 and 86 define the straight hole 74 over their co-extensive straight portions.

Extending through the left bending hub 80 of the upper die block 64 is a bore 90 which is aligned with a bore 92 in the left bending hub 68 of the lower die block 66. Similarly, the right bending hub 84 of the upper die block 64 has a bore 94 which is in alignment with a bore 96 extending through the right bending hub70 of the lower die 66.

The

aligned bores

90 and 92 are coaxial with the axis about which the bending die assembly 62 rotates when a tube is bent about the left bending hub 68. Similarly, the

aligned bores

94 and 96 are co-axial with the axis about which the bending die assembly 62 rotates when the tube is bent about the right bending hub.

In order to position the tube for each bend, it is pushed through the hole 74 until the location at which a bend is to be formed is reached. At that point the advancing tube is stopped and the bending die assembly 62 is rotated, the direction of rotation depending upon the direction the tube is to be bent.

The distance the tube is moved through the hole 74 will, of course, depend upon the distance between adjacent bends in the finished serpentine configuration. The distance will probably not be the same between the various bends, so that preferably the present invention is provided with a means of programming into it the distance between the bends and the degree to which the tube is to be bent at each bend location. It is desirable that the operation also be programmed so that no weld in the tube is present at or near the location where the bend is formed.

To form a bend with smoother sidewalls by eliminating ripples, a pressure wiper die 100 is provided. The pressure wiper die 100 has two

die halves

102 and 104 between which the tube extends and which move toward each other to apply pressure when the bend is being formed and away from each other to release the tube to permit it to pass through the pressure wiper die. As shown best, perhaps, in FIG. 6, the die half 102 is provided with a groove 106 running along its length which faces a groove 108 in the die half 104. The tube passes through the wiper die 100 so that it is always within the

grooves

106 and 108. The pressure wiper die

halves

102 and 104 are moved relatively to one another by hydraulic cylinders. They each are activated in the same manner and therefore only one is shown in detail in FIG. 6. A hydraulic cylinder 110 moves the die half 102 into position through an eccentric 112 which acts on a sliding die cradle 114. When the die half 102 has been moved so that it is as close to the die half 104 as possible, pressure is exerted by means of a hydraulic cylinder 120 which acts through an eccentric 122 to apply a force to an arm 124 in the sliding die cradle 114.

The die half 102 has a nose portion 126 which is curved in plan and the die half 104 has a nose portion 128 which is curved in plan. The

nose portions

126 and 128 are on the for ward end of the die halves 102 and 104 respectively, as shown in FIG. 5, and are positioned between the bending

hubs

68 and 70 in engagement with the hubs when the bending die assembly 62 is in a neutral position, i.e., a position when it exerts no torque on a tube extending through the hole 74.

It has already been explained that torque is applied to the tube by rotating the bending die assembly 62 about one of the axes of the

bending hubs

68 or 70. In order to allow a tube to move through the straight hole 74 when the tube is being positioned'for a subsequentbending operation, and in order to permit the

grooves

72, 82, 76 and 86 to bear against the tube over half of its outer surface when being bent, it is necessary to provide means to move the upper die block 64 and the lower die block 66 with respect to one another.

The upper die block 64 is raised and lowered with respect to the lower block 66 by means of a hydraulic cylinder 130 (FIG. 3) which acts through a rod 132 secured to the upper die block 64. The hydraulic cylinder 130 never moves in relation to the lower block 66 because it is apaced therefrom by supporting

columns

134 and 136. The column 134 extends through the

bores

90 and 92 and is secured to the lower die block 66 and slide block 60 by screw threads as shown. The column 134, however, is not snugly engaged within the bore 90 so that the upper die block 64 is not prevented from moving vertically by the column 134. Similarly, the column 136, which extends loosely through the bore 94, extends into the bore 96, is threadably engaged therein, and is secured to the slide block 60. The bending die assembly 62 including the lower die block 66 and the upper die block 64 is raised and lowered by means of a hydraulic cylinder 140 (FIG. 1) which acts on the shaft 48, support block 52 and slide block 60 to raise and lower the die assembly 62. To separate the upper die block 64 and lower die block 66, the cylinder 140 lowers the entire die assembly 62 while the cylinder 130 raises the upper die block 64. To position the upper and lower blocks together, the cylinder 140 raises the die block assembly 62 while the cylinder 130 lowers the upper die block 64.

When the tube has been positioned in preparation for the formation of a bend and the pressure wiper die 100 has been activated so that the die halves 102 and 104 exert pressure on the tube, the upper die block 64 and the lower die block 66 of the bending die assembly 62 are moved together. Thereafter, the bending tube assembly 62 is rotated about one of the axes of the

bending hubs

68 or 70.

In order to allow the bending die assembly to rotate selectively about one of two different axes, the shaft 48 is moved laterally with respect to the bending die assembly. When this happens the support block 52 moves in relation to the die assembly 62 because the slide block 60 remains stationary. To this end, the bending die assembly 62 is provided with two

bearings

144 and 146, each positioned co-axially with an axis of one of the

bending hubs

68 or 70. Thus, as shown in FIG. 3, the bearing 144 is axially aligned with the axis of the left bending hub 68 while the bearing 146 is axially aligned with the axis of the right bending hub 70. If it is desired to bend the pipe to the left, i.e., about the left bending hub 68, the shaft 48 is translated by means of a hydraulic cylinder 148 (FIG. 2) until the shaft 48 is aligned with the bearing 144. (The cylinder 148 actually moves the entire frame 12 so that the shaft 32, clutch 34 and

hydraulic cylinders

24 and 26 move with it.) At this point, a hydraulic cylinder 152 (FIG. 1) acts on a rod 154 which extends axially through the shaft 48 to push a pivot pin 156 upwardly and into engagement with the bearing 144. When the pivot pin 156 is in the bearing 144, a locking pin 158 is moved under it by a cylinder 160. The

hydraulic cylinders

24 and 26 rotate the shaft 32 and the sprockets 30, the sprockets 46 through the chain 44, and thus the shaft 48 is made to turn. Rotation of the shaft 48 imparts rotation to the support block 52 and the slide block 60. The slide block 60 is of course a component of the bearing die assembly 62 which will rotate about the axis of the shaft 48, which is also the axis of the pin 156 and the left bending hub 68. When the bend is completed, the upper die block 64 and lower die block 66 are moved apart, as are the

die halves

102 and 104 of the pressure wiper die 100. The bending die assembly 62 is rotated to its neutral position and the tube is advanced through the pressure wiper die and the bending die assembly 62 until a location of the tube in which a bend is to be made is positioned in the bending die assembly 62. If a left hand bend is to be made, the pressure wiper die

halves

102 and 104 are moved together and made to exert pressure on the tube. Similarly, the lower die 66 and upper die block 64 are moved closer together and the bending die assembly is rotated to the left as hereintofore described. If a right hand bend is to be made, the shaft 48 is translated until the pin 156 can be engaged within the bearing 146. The

hydraulic cylinders

24 and 26 then rotate the shaft 48 to the right to make the bend.

FIG. 7 shows a pair of die blocks having an upper die block 172 and a lower die block 174. The upper die block 172 and lower die block 174 are basically similar to the die blocks 64 and 66 having

grooves

176, 178, and 182, which correspond to the

grooves

72, 76, 82, and 86 respectively. The

grooves

176, 178, 180 and 182 all merge in straight segments to form the straight hole 184 through which the tube is moved in preparation for bending. The die block 172 has

bores

186 and 188 which correspond to

bores

90 and 94, while the die block 174 has

bores

190 and 192 which correspond to the

bores

92 and 96 of the die block 66.

The basic difference between the die blocks 172 and 174 and the die blocks 64 and 66 is that the die blocks 172 and 174 are larger. The distance R controls the radius of bend in the tube so that the die blocks shown in FIG. 7 will create a larger bend radius than the die blocks shown in FIG. 3. If larger die blocks such as 172 and 174 are used, a slide block larger than the slide block 60 must be used so that the bearings will be farther apart than the

bearings

144 and 146. This is necessary so that the axes of rotation will be the proper distance apart to allow for a larger bend radius. If the

bores

186 and 190 are aligned with a bearing in the support block and the

bores

188 and 192 are aligned with such a bearing, the distance S will correspond to the distance between bearings. This distance will, of course, be larger than in the case where smaller die blocks are used and the pin 156 will move a greater distance when moving between bearings to change the axis of rotation of the die assembly. This is possible because the slide block can slide in the supportblock 52 any distance which is necessary to assure engagement between the pin 156 and the bearing which will form the axis of rotation.

' The foregoing describes but one preferred embodiment and other embodiments can be constructed by making additions, subtractions and/or substitutions of elements in the abovedescribed embodiment without exceeding the scope of the invention as defined in the following claims.

What is claimed is:

1. Apparatus for bending a tube comprising a die assembly having a central opening for receiving said tube, two bending surfaces, one on each side of said opening, and two axes of rotation, one on either side of said tube, two bearings in said die assembly, each of said bearings being concentric with one of said axes of rotation, a pin which is capable of being in serted in the bearing concentric with the axis of said bending die assembly about which said bending dieassembly is to be rotated to bend said tube, the other of said bearings being free to allow said die assembly to rotate about said engaged bearing, and means to rotate said die assembly about either of said axes in either direction whereby when it is desired to bend said tube toward one of said axes, said assembly is rotated about that axis so that the tube is bent about the bending surface on the same side of said tube as said one axis.

2. The apparatus defined in claim 1 wherein said pin is mounted in a support block for axial movement therein, said apparatus further comprising a slide block connected to said bending die assembly, said bearings being in said support block, one of said slide blocks and said support block having a groove in a surface thereof, the other of said support blocks and said slide block being slideably engaged in said groove so that said slide block and said support block can be slid with respect to one another so that said pin can be engaged in either of said bearings, said means to rotate said die assembly acting on said slide block.

3. The apparatus defined in claim 2 wherein said support block is moveable to position said pin in either of said bearings.

4. The apparatus defined in claim 3 wherein said groove is in said support block and a portion of said support block is slideably engaged in said groove.

5. The apparatus defined in claim 1 wherein said die as sembly comprises an upper die block and a lower die block, means to hold said die blocks from relative horizontal move ment while permitting relative vertical movement, means to move said die blocks apart to permit said tube to be advanced through said die assembly and means to push said die blocks together to hold said tube during bending.

6. The apparatus defined in claim 1 further comprising a pressure wiper die, said die being positioned so that when said tube is advanced through said bending die assembly said tube passes first through said pressure wiper die, said pressure wiper die comprising laterally disposed die halves, said die halves each having a groove facing a corresponding groove in the other die half, means to move said die halves together and against said tube to clamp said tube in said grooves and means to move said die halves apart to release said tube.

7. The apparatus defined in claim 6 wherein each of said die halves has a curved nose portion complimenting and in engagement with the adjacent bending surface on said bending die assembly when said axes of rotation lay on a line perpendicular to said tube so that when said bending die is rotated about one of said axes of rotation the curved nose portion closest to that axis stays in contact with the bending surface closest to that axis.

Claims

1. Apparatus for bending a tube comprising a die assembly having a central opening for receiving said tube, two bending surfaces, one on each side of said opening, and two axes of rotation, one on either side of said tube, two bearings in said die assembly, each of said bearings being concentric with one of said axes of rotation, a pin which is capable of being inserted in the bearing concentric with the axis of said bending die assembly about which said bending die assembly is to be rotated to bend said tube, the other of said bearings being free to allow said die assembly to rotate about said engaged bearing, and means to rotate said die assembly about either of said axes in either direction whereby when it is desired to bend said tube toward one of said axes, said assembly is rotated about that axis so that the tube is bent about the bending surface on the same side of said tube as said one axis.

5. The apparatus defined in claim 1 wherein said die assembly comprises an upper die block and a lower die block, means to hold said die blocks from relative horizontal movement while permitting relative vertical movement, means to move said die blocks apart to permit said tube to be advanced through said die assembly and means to push said die blocks together to hold said tube during bending.