US3685334A

US3685334A - Bending machine

Info

Publication number: US3685334A
Application number: US13982A
Authority: US
Inventors: Ernest C Sindelar
Original assignee: Pines Engineering Co Inc
Current assignee: Pines Engineering Co Inc
Priority date: 1970-02-25
Filing date: 1970-02-25
Publication date: 1972-08-22
Anticipated expiration: 1989-08-22

Abstract

A tube bending machine having the capability of releasing the tube from the carriage for longitudinal movement during bend formation, while maintaining a plane of bend reference. The end of the tube is connected with a rod extending through the carriage collet. The rod has a non-round cross-section and extends through a mating adapter on the carriage which permits relative longitudinal movement while preventing relative rotation between them.

Description

United States Patent Sindelar [451 Aug. 22, 1972.

[54] BENDING MACHINE [72] Inventor: Ernest C. Sindelar, Sugar Grove, 111.

[73] Assignee: Pines Engineering Co., Inc.

[22] Filed: Feb. 25, 1970 [21] Appl. No.: 13,982

52 us. Cl. ..72/311, 72/156, 72/369, 72/422 51 Int. Cl. ..B2ld 11/04 [58] Field of Search ..72/156, 293, 311, 318, 250, 72/369, 422, 149, 150, 298, 301, 10, 14, 23,

[56] References Cited I UNITED STATES PATENTS 3,553,989 l/l971 Munro et a1. ..72/8 2,306,223 12/ 1942 Parker et a1. ..72/ 150 3,336,776 8/1967 Zerlaut ..72/14 3,475,938 11/1969 Whitney, Jr. et a1. ..72/159 3,426,562 2/ 1969 Inda ..72/24 2,312,121 2/1943 Parker et a1. ..72/156 Primary Examiner-Charles W. Lanham Assistant Examiner-Michael .1 Keenan Attorney-Hofgren, Wegner, Allen, Stellman & Mc- Cord [57] ABSTRACT A tube bending machine having the capability of releasing the tube-from the carriage for longitudinal movement during bend formation, while maintaining a plane of bend reference. The end of the tube is connected with a rod extending through the carriage collet. The rod has a non-round cross-section and extends through a mating adapter on the carriage which permits relative longitudinal movement while preventing relative rotation between them.

7 Claims, 4 Drawing Figures 'BENDING MACHINE This invention is primarily concerned with a means for maintaining the validity of a bend angle plane in a tube bender without clamping or securing the work to a longitudinal positioning mechanism during the bending operation.

In a rotary tube bender, for example, a length of tube is held at one end, as by a releasable collet, on a movable carriage. The tube extends along a rotary die against which it is clamped during the bend operation. A pressure die is held against the tube during rotation of the bending die to cause formation of the bend without excessive deformation of the tube.

Prior to the bending operation the collet is clamped to the tube, and the carriage moves the tube to the desired bend position and rotates the tube with respect to the plane of the bend arm to the desired bend angle plane. During the bending operation the collet may be clamped to the tube to cause it to move with the car riage, or may be released so that the carriage and tube collet is clamped or released. If the collet is released during the bending operation the tube may rotate with respect to the plane of the bend arm thereby preventing the production of the desired bend angle plane. This is particularly a problem where it is desired to maintain an accurate bend plane reference during the bending operation. If the collet is not released during the bending operation, the carriage is pulled forward as the bend is made, a tube having a low elastic limit will be deformed or stretched. The amount of strain produced will depend upon such factors as tube diameter, wall thickness, elasticity, temper, and tensile strength of the material, and the like. Occasions will arise where the above characteristics of the work are such that the amount of strain introduced is excessive resulting in an impermissible amount of error in the finished tube dimensions. The present invention provides a means, other than clamping the tube in the collet, to prevent tube rotation during the bending operation where neither of the above two types of dimensional errors is allowable.

The principal object of this invention,,therefore, is to provide an improved means for preventing tube rotation in a tube bender during the bending operation.

Another object of this invention is to provide means to prevent tube strain while maintaining the validity of the bend plane angle during the bending operation in a tube bender as described above. I

A further object of this invention is to make such an aforementioned rotation prevention means readily mountable on and removable from the bending machine.

Still another object of this invention is to provide such an improved rotation prevention means adaptable for use with tubes of various sizes or tubes with various shaped end fittings.

Other objects, features, and advantages of this invention will readily be apparent from the following specification and from the accompanying drawings of which:

FIG. 1 is a diagrammatic plan view of a rotary tube bender at the start of a bend showing the relative position to the carriage, rod, shaft, and guide means;

FIG. 2,is a fragmentary diagrammatic plan view of the guide means and guide mounting means taken generally along line 3-3 of FIG. 1; and

FIG. 4 is an enlarged sectional view of the guide means taken generally along the line 44 of FIG. 3.

In the drawings and in the following description there is disclosed only so much of the bending machine'that is directly pertinent to the invention. The bending machine has a base 10 on which carriage l l is mounted for longitudinal and rotary movement. The carriage 11 includes clamp means 12 in which a length of tube 13 to be bent is carried. Clamp means 12 may be clamped to tube 13 to cause it to move with carriage 11, or may be released so that carriage 11 and tube 13 may move independently.

The bending tools include a rotary bending die 14, a tube clamp 15, and a pressure die 16. Bending die 14 has a groove 14a in the side wall thereof with a depth slightly less than the radius of tube 13. The die has a semi-circular peripheral portion 14b at the left (as shown in FIG. 1) with two parallel straight sided sections 14c tangent thereto. The bending die is rotatable about the axis of shaft 17 with which semi-circular end portion 14b is concentric. Clamp 15 has an end portion 150, also with a tube receiving groove therein, which holds the tube against the straight sided portion 140 of the bending die. The clamp is movable toward and I away from the bending die. Clamp 15 is mounted on end of a 90 bend. Bend arm 18, bending die 14 and tube clamp 15 have moved to an arc of 90 and tube bend;

clamp 15 holds tube 13 against bending die 14. Pressure die 16 has moved in a straight line a distance equal to the arc of the bend and still holds the trailing edge of tube 13 straight and against the peripheral portion of the bending die 14a.

In normal course of bending operation (previous to this invention) a straight tube l3 is inserted through clamp means 12 on carriage 11 and carriage 11 is moved longitudinally to position tube 13 at the appropriate point for the start of a bend at the tangent point between the semi-circular 14a and straight 14b portions of bending die 14. At the same time, carriage 11 rotates (if necessary) so that the plane of the bend is properly related to the previous bend or to a particular orientation of an end fitting on tube 13. When the tube is positioned for the bend, carriage 11 stops and tube clamp 15 and pressure die 16 close, and the bend is formed. During the bend, clamp means 12 is released, the tube end is loosely received in clamp means 12, and the portion of tube 13 used in forming the bend is drawn out. When the bend is completed, clamp means 12 is reclosed, and tube clamp 15 and pressure die 16 are released, providing suflicient clearance for tube 13 to move. Carriage 11 then positions the tube 13 for a new bend. The difficulty encountered with the above approach is that during the bending operation when clamp means 12 is released tube 13 may rotate so that the plane of a subsequent bend may not be properly related to the plane of the first bend.

An alternate approach may be used, where during the bending operation clamp means 12 on carriage 11 is not released and the carriage moves forwardly with tube 13 and while tube 13 is wrapped around bending die 14. The difficulty encountered using this approach is that if the tensile strength of the tube is sufficiently low the tube will stretch excessively from the drag of the carriage.

In particular the problem has been encountered in bending a small diameter coaxial cable having a connector fitting at one end which requires precise angular orientation. Using the present invention described herein, both of the above aforementioned problems are resolved. In the present invention (FIG. 1) the tube 13 is connected to elongated rod 22 by tube connector 20. The elongated rod 22 extends through clamp means 12. Elongated rod 22, in turn, is connected to non-circular shaft 14 by rod connector 16 (FIG. 3). Non-circular shaft 24 extends through guide means 28 which is mounted in the end of tubular member 30, at the rear of carriage l 1.

Referring now to FIG. 4, a cross-section of a particular embodiment of the guide means 28 is shown. In this embodiment the guide means comprises outer surface 42, inner cylindrical surface 44, and a plurality of rotatable ball bearings 46 carried by and projecting inwardly from inner cylindrical surface 44. The non-circular shaft 24 has a plurality of splines 50 extending into the spaces between ball bearings 46. Non-circular mating surface 52 of shaft 24 with ball bearings 46 and inner cylindrical-surface 44, prevents relative rotation between guide means 28 and splined shaft 48, while the rotatable ball bearings 46 allow and enhance freedom of relative longitudinal movement between guide means 28 and splined shaft 48.

A movable shaft stop means 40 is mounted on non circular shaft 24 so as to prevent shaft 24 from inadvertently sliding through the guide means 28. Although a particular embodiment of the guide means and shaft means is herein disclosed, it should be noted that any non-circular shaft 24 extending through guide means 28 and mating therewith will serve equally as well.

Utilizing the present invention, after the guide means is mounted and the shaft, rod, and tube are secured, the normal course of a bending operation would be as follows: tube 13 is secured to connector 20 on the rod 22; rod 22 is secured to carriage 11 by clamp means 12; carriage 11 is moved longitudinally and rotationally to the desired position for the bend; clamp means 12 is released and the bending operation is performed.

Since during the actual bending operation, the clamp means 12 is released, tube 13 is allowed to move longitudinally carrying rod 22 and shaft 24 with it. However, shaft 24 prevents relative rotation between car riage 11 and tube 13, maintaining the desired angular reference, At the end of a bend operation clamp means 12 is reclosed, again securing rod 22 and hence tube 13 to carriage 11. The carriage can then move the tube to a new bend position.

Guide means housing 31 has threaded extension 32 on which is threaded shoulder means 33, expandable circular ring 34,and threaded collar 36. Guide means 28 is secured to tubular member 30 when threaded collar 36 is tightened against shoulder means 33, thereby compressing expandable circular ring 34 against shoulder 33, expanding it outwardly to grip inner wall 38 of tubular member 30.

The foregoing detailed description has'been given for clearness of understanding only and no unnecessary limitation should be understood therefrom as some modification will be obvious to those skilled in the art.

I claim: 1. In a tube bender having a tube clamp, bend arm, and an elongated carriage with clamp means, said car riage being movable longitudinally to position the tube with respect to said tube clamp and rotatable to position the tube with respect to the plane of the bend arm, means for preventing rotation of the tube during the bending operation, comprising:

an elongated rod extending through said clamp means and having means for securing the tube thereto; and

means for preventing rotational movement of said rod with respect to said carriage while allowing the rod to be drawn from said carriage and clamp means during the bending operation.

2. The tube bender of claim 1, wherein said rotation preventing means comprises: a guide means secured to said carriage; and a non-circular shaft secured to said rod, with said shaft extending through said guide means and mating therewith, preventing relative rotation and allowing relative longitudinal movement between the guide means and the non-circular shaft.

3. The tube bender of claim 2, wherein said non-circularv shaft comprises, a shaft with longitudinal splines extending along the length thereof.

4. The tube bender of claim 3, wherein said guide means comprises: a housing with inner and outer cylindrical surfaces mounted coaxially with the carriage, and a plurality of rotatable ball bearings carried by and projecting inwardly from said inner cylindrical surface.

5. The tube bender of claim 2, wherein said guide means has mounting means for temporary mounting on said carriage.

6. The tube bender of claim 5 in which said carriage includes a tubular member having an end in which said guide means is mounted, said guide means including an expandable ring seated against a shoulder and a threaded collar movable to compress said ring against said shoulder and expand it outwardly to grip the inner wall of the tubular member of said carriage.

7. The method of performing a bending operation with a tube bender having a bending mechanism and a carriage with tube clamp means thereon, movable longitudinally and rotatably to position a tube with respect to said bending mechanism, comprising:

connecting the tube to a rod free to move longitudinally with respect to the carriage and restrained against movement rotationally with respect thereto;

securing said tube to said carriage by said clamp means, for movement therewith;

longitudinally moving said carriage to position said tube with respect to said bending mechanism; rotating said carriage to orient said tube angularly with respect to said bending mechanism;

securing said tube in said bending mechanism;

opening said tube clamp means on the carriage to release said tube for longitudinal movement with respect to said carriage, the connection of the tube to said rod maintaining the angular reference between the tube and the carriage;

performing the bending operation;

closing said clamp means; and

positioning said tube for the next bending operation.

Claims

1. In a tube bender having a tube clamp, bend arm, and an elongated carriage with clamp means, said carriage being movable longitudinally to position the tube with respect to said tube clamp and rotatable to position the tube with respect to the plane of the bend arm, means for preventing rotation of the tube duRing the bending operation, comprising: an elongated rod extending through said clamp means and having means for securing the tube thereto; and means for preventing rotational movement of said rod with respect to said carriage while allowing the rod to be drawn from said carriage and clamp means during the bending operation.

3. The tube bender of claim 2, wherein said non-circular shaft comprises a shaft with longitudinal splines extending along the length thereof.

7. The method of performing a bending operation with a tube bender having a bending mechanism and a carriage with tube clamp means thereon, movable longitudinally and rotatably to position a tube with respect to said bending mechanism, comprising: connecting the tube to a rod free to move longitudinally with respect to the carriage and restrained against movement rotationally with respect thereto; securing said tube to said carriage by said clamp means, for movement therewith; longitudinally moving said carriage to position said tube with respect to said bending mechanism; rotating said carriage to orient said tube angularly with respect to said bending mechanism; securing said tube in said bending mechanism; opening said tube clamp means on the carriage to release said tube for longitudinal movement with respect to said carriage, the connection of the tube to said rod maintaining the angular reference between the tube and the carriage; performing the bending operation; closing said clamp means; and positioning said tube for the next bending operation.