GB2146275A

GB2146275A - Tube benders

Info

Publication number: GB2146275A
Application number: GB08412430A
Authority: GB
Inventors: Leonard J Kowal; Albert J Schwarz
Original assignee: Imperial Clevite Inc
Current assignee: Clevite Industries Inc
Priority date: 1981-01-30
Filing date: 1984-05-16
Publication date: 1985-04-17
Also published as: GB2146275B; GB2092036B; DE3201770A1; CA1180259A; FR2498953B1; FR2498953A1; GB2092036A; GB8412430D0

Abstract

A tube bender (210) for manual operation in bending a tube (T) includes a form wheel (211) defining a bending groove (212) into which the tube is urged by a forming member (213) mounted to the form wheel to swing about a bending axis of the grove. The tube is held against longitudinal movement during the bending operation by means of a hook (218) swingably mounted to the form wheel. Movement of the forming member about the bending axis is effected by manipulation of a handle (219) connected to the form wheel (211). The forming member (213) is swingably mounted to the form wheel (211) to be adjustable towards and from the form wheel groove (212) to accommodate variations in tube diameter and normal wear of portions of the tube bender during the life thereof. The form wheel defines a concave force transfer surface (242) having an improved engagement with the tube to be bent so as to effectively improve maintained tube roundness for effectively minimized stress formation in the bent tube. <IMAGE>

Description

1 GB2146275A 1

SPECIFICATION

Tube benders This invention relates to tube benders.

According to the invention there is provided a tube bender comprising a form wheel defining a tube-receiving bending groove extending arcuately about a bend axis, means for hold- ing a tube to be bent against longitudinal movement in the bending groove during a tube bending operation, a forming member defining a concave tube- engaging surface, and adjustable mounting means for mounting the forming member to the form wheel to swing about the bend axis outwardly adjacent the bending groove at any one of a plurality of different distances radially from the bend axis to have desired bending force transfer engagement with the tube to be bent outwardly of the bending groove.

By means of the invention, accurate disposition of the forming member relative to the bending groove of the form wheel can be maintained, notwithstanding wear on the corn- 90 ponents of the tube bender and permitting desired force transfer engagement between the forming member and the tube to be bent, notwithstanding variations in the diameter of the tube to be bent.

Thus, a tube bender constructed in accordance with the invention can accommodate a range of different tube sizes, permitting the use of metric and conventional English dimen- sion tubing with similar efficacy in effecting the bending. Thereby, the invention eliminates the need for the provision of different configuration forming member elements in utilization of the tube bender alternatively with such different dimensional tubing.

In order that the invention may be well understood there will now be described an embodiment thereof, given by way of example, reference being had to the accom- panying drawing, in which:

Figure 1 is a fragmentary side elevation of a tube bender illustrating, in broken lines, an adjusted position of the forming member thereof; Figure 2 is a fragmentary transverse section 115 taken substantially along the line 11-11 of Fig.

1; Figure 3 is an elevation of the eccentric forming member adjusting means pin of the same tube bender; Figure 4 is a transverse section illustrating in greater detail the improved force transfer surface configuration of the forming member of the same tube bender; and Figure 5 is a transverse section illustrating another form of force transfer surface configuration.

A manually operable tube bender generally designated 210 includes a form wheel 211 defining an annular peripheral bending groove 130 212. A tube to be bent T is bent into the forming groove by a forming member 213. The forming member is swung about a bending axis 214 of the groove 212 by means of a swing link 215 having one end pivotally connected to the forming member by a pivot 216 and the opposite end connected to the forming member 213 by a pivot connection 217.

The tube T is held against longitudinal displacement during the bending operation by a hook 218.

Movement of the forming member 213 relative to the form wheel 211 is effected by manipulation of a handle 219 connected to the form wheel 211. As shown in Fig. 1, when the handle 219 is swung to bring the forming member 213 to a bend-start position, the link 215 is positioned by its egagement with a suitable stop shoulder element pro- vided on a rear face 222 of the form wheel 211. As further illustrated in Fig. 1, the forming member 213 may be provided with an indicium 223 juxtaposed to a scale 224 carried by the form wheel 211 for indicating the disposition of the forming member 213 in the bend-start position illustrated in Fig. 1 and for indicating the angular extent of the bend formed in the tube.

A problem arises in swingable forming member tube benders in that, as a result of wear of the components of the tube bender, a loose fit may result between the forming member and the tube held in the bending groove. It is necessary to have proper force transfer engagement of the forming member with the tube in order to prevent undistorted bends and to meet standards of ovality of the bent tube such as required by the Nuclear Code, etc. One solution to this problem em- ployed in heavy duty bench-type tube benders is to provide a screwed clamping arrangement which forces a contoured follower shoe against the tubing prior to the bending. The contoured shoe is a separate loose piece which is placed in position and requires that the clamping adjustment must be made and released each time a bend is made with the tool. High frictional forces are generated as a result of the requirement of high clamping force. In such a structure, the follow bar is a loose member which is free to move longitudinally of the tube bend so that the tube will remain undamaged. The necessary high forces would require, in a manually operable tube bender, extremely long operating handles to provide the necessary moment arms.

The present embodiment eliminates the need for such adjustable contoured shoe structures by providing means for adjusting the position of the forming member 213 towards and from the peripheral edge 225 of the form wheel 211 so as to cause the forming member to have the desired accurate force transfer engagement with the tube T. More particularly, the adjustment of the form- 2 GB 2 146 275A 2 ing member 213 is effected by the provision of an adjustable pivot 217 defined by a pivot pin having a first mounting portion 226 pivotally mounted in a bore 227 of the forming member body 228, as illustrated in Fig. 2. A second cylindrical portion 229 of the pivot pin 217 is pivotally received in a bore 230 of the link 215. The axis 231 of the cylindrical portion 229 is offset from the axis 232 of the cylindrical portion 226 and, thus, the pivot pin 217 defines an eccentric pin. As further shown in Fig. 2 one end of the pin 217 is provided with a head 233 adapted to be engaged by a suitable tool, such as a wrench, and the opposite end of the pin is threaded as 80 at 234 for threaded engagement with a suit able nut 235.

Adjustment of the forming member 213 towards and from the form wheel edge 225 is effected by turning the head 233 so as to 85 displace the axis 232 of the cylindrical portion 226 towards or from the form wheel edge 225 as it swings about the axis 231 of the cylindrical portion 229. During such adjust ment, the nut 235 may be loosened on the threaded end 234 and upon completion of the adjustment, retightening of the nut 235 se cures the pivot means in the adjusted disposi tion.

As will be realized by those skilled in the art, the eccentric adjusting means is exem plary, and any suitable means for adjusting the position of the forming member 213 radially of the bend axis 214 may be utilized.

As shown in Fig. 1, the scale 224 may comprise a scale adjustably mounted to the form wheel 211 by a suitable screw 236 extended through an arcuate slot 237 in the scale 224. Thus, the scale 224 may be ad- justed to line up with the indicium 223 identifying the bend-start point in each of the adjusted positions of the forming member.

Whilst in the illustrated embodiment the adjusting means is infinitely adjustable, it will be apparent to those skilled in the art that 110 discrete adjusting means may also be utilized.

The forming member 213 is provided with a pair of rollers 238 and 239 which are rotatably mounted between a pair of side plates 240 and 241 depending in spaced relationship from the forming member body portion 228. The roller 238 is axially aligned with the bend- start indiciurn 223 and the roller 239 is spaced outwardly therefrom so as to engage a portion of the tube T longitudi- 120 nally outwardly from the portion engaged by roller 238, and, as seen in Fig. 1, at a position spaced radially outwardly of the edge 225 of the form wheel 211. Thus, as the handle 219 is swung in a clockwise direction, 125 as seen in Fig. 1, the forming member rollers 238 and 239 cooperate in bending the tube into the form wheel groove 212, with the leading roller 239 firstly deflecting the outwardly extending portion of the tube T toward 130 the form wheel edge 225 and the roller 238 urging the tube firmly into the groove.

The tube bender 210 also incorporates a novel force transfer surface on the forming member 213 for transferring the bending force from the forming member to the tube T. As best seenin Fig. 4, the forming member defines a concave tube-engaging surface generally designated 242 for engaging the tube and effecting the force transfer thereto. The tube-engaging surface further defines side surface portions 243 and 244 engaging side portions 245 and 246 of the tube outwardly adjacent the form wheel edge 225 and 212 therein. The concave surface 242 further defines a bight portion 247 between the surface portions 243 and 244 arranged to have clearance with the radially outermost portion 248 of the tube between the side portions 245 and 246.

Engagement between the forming member force transfer surface portions 243 and 244 and the tube is over a limited angular extent illustrated in Fig. 4 as angle 0. The side portions of the tube 245 and 246 engaged by the side surfaces of the forming member are angularly spaced at least approximately 15 degrees from a plane 249 drawn through the cross-sectional centre 250 of the tube perpendicular to a radius 251 extending through said tube centre 250 from the bend axis 214. The side portions of the tube engaged by the forming member extend outwardly to a position no greater than approximately 45 degrees from plane 249 and, thus, the angle 4) extends approximately 30 degrees in the illustrated embodiment.

As illustrated in Fig. 4, the side surfaces 243 and 244 of the forming member may be rectilinear in transverse cross section so as to have effectively minimum surface contact with the engaged surfaces of the tube 245 and 246. Alternatively, however, the surfaces of the forming member may be rounded, such as surfaces 252 and 253 of the forming member 254 illustrated in Fig. 5. Thus, as shown in Fig. 4, the bight portion 247 is substantially trapezoidal in transverse cross section, whereas, alternatively, the bight portion 255 of the forming member 254 can be rounded, such as in an arch configuration, in transverse section, as shown in Fig. 5. The specific configuration of the bight portion of the concave surface does not appear to be critical as long as clearance is provided relative to the outermost portion 248 of the tube to be bent with the force transfer engagement of the forming member side surface portions being with portions of the tube outwardly of the form wheel groove of limited angular extent.

As a result of the force transfer from the force transfer surface portions of the forming member hereof, the tube bending forces are applied at a region of the tube where a relatively thick wall is maintained as compared 3 GB 2 146 275A 3 to the stretched outermost portion 248 thereof.

No direct flattening force is applied to the outermost portion 248 of the tube, and the bending forces transmitted from the bending 70 surfaces 243, 244, 252 and 253 define transversely inwardly directed components re sisting lateral spreading of the tube, thereby further effectively minimizing flattening or in creased ovality of the tube as a result of the 75 bending operation.

At least the roller disposed adjacent the bend-start position, such as the roller 238, is provided with the concave force transfer confi- cludes a swing member pivotally mounted to the form wheel, means for adjustably mount ing the forming member to the swing mem ber, and shoulder means on the form wheel for positioning the swing member in a prese lected bend-start position for permitting ad justment of the radial positioning of the form ing member with the forming member dis posed in the bend-start position thereof.

3. A tube bender as claimed in claim 1 or claim 2, wherein the form wheel is provided with an angle scale adjustably mounted thereto.

4. A tube bender substantially as herein guration discussed above. The outboard roller, 80 described with reference to the accompanying such as the roller 239 may also utilize the drawing.

same surface configuration, although it has been found that satisfactory bending of the tube may be effected with the outboard roller utilizing a conventional tube-engaging surface configuration. As will be realized to those skilled in the art, where the forming member comprises a shoe wherein the force transfer surface is defined by a longitudinal groove in the shoe, the entire groove transverse cross section may utilize the above discussed im proved force transfer configuration. It is pre ferred that at least the portion of the groove adjacent the bend-start point has such a confi guration.

The adjustability of the forming member towards and from the bending groove permit ted by the adjustable mounting means coop erates with the force transfer surface configu ration in providing a tube end with minimum stress and ovality. Thus, the tube bender structure 210 complies with the relatively strict nuclear power plant requirements for bent tubes, as set out in Section Ill of the ASME Code, while yet the tube bender struc ture is extremely simple and economical of construction.

Attention is drawn to our copending patent application No. 8201597 (Serial No.

2092036) from which the present application is divided.

Claims

1. A tube bender comprising a form wheel defining a tube-receiving bending groove ex tending arcuately about a bend axis, means for holding a tube to be bent against longitu dinal movement in the bending groove during a tube bending operation, a forming member defining a concave tube-engaging surface, and adjustable mounting means for mounting the forming member to the form wheel to swing about the bend axis outwardly adjacent the bending groove at any one of a plurality of different distances radially from the bend axis to have desired bending force transfer engagement with the tube to be bent out wardly of the bending groove.

2. A tube bender as claimed in claim 1, wherein the adjustable mounting means in- Printed in the United Kingdom for Her Majesty's Stationery Office, Dd 8818935, 1985, 4235. Published at The Patent Office, 25 Southampton Buildings, London, WC2A l AY, from which copies may be obtained.