WO2008051162A1

WO2008051162A1 - Tool for pipe bending and former for use in such a tool

Info

Publication number: WO2008051162A1
Application number: PCT/SE2007/050776
Authority: WO
Inventors: Mårten ANDRÉN; Olle Bobjer; Hans Himbert; Stefan Strandberg; Mattias LÖVEMARK; Conny Jansson
Original assignee: Kapman Ab
Priority date: 2006-10-26
Filing date: 2007-10-24
Publication date: 2008-05-02
Also published as: CN101528375B; NO20090869L; CN101528375A; US20090266137A1; EP2076340A1; EP2076340A4

Abstract

The present invention relates to a tool for pipe bending comprising at least two branches (1, 3), at least one link arm (8), at least one former (7), and at least one sliding jaw (9), said at least one former (7) and said at least one sliding jaw (9) being intended to be placed on either side of a pipe (12) to be bent, and said at least one former (7) being fitted to, or constituting a part of, a first branch (1 ) of said at least two branches (1, 3) at the same time as said at least one sliding jaw (9) being fitted to, or constituting a part of, a second branch (3) of said at least two branches (1, 3). At least one of said at least one former (7) has at least one pipe- positioning index (18, 19), one of which is intended to be placed as close as possible to a corresponding bending-measure index on the pipe (12) when the pipe (12) is placed in the tool in order to be bent. The present invention also relates to a former (7) for use as a part of a tool for pipe bending.

Description

Tool for pipe bending and former for use in such a tool .

The present invention relates to a tool for pipe bending comprising at least two branches, intended to be gripped and pressed together by an operator upon pipe bending, at least one link arm, at least one former, and at least one sliding jaw, said at least one former and said at least one sliding jaw being intended to be placed on either side of a pipe to be bent, and said at least one former being fitted to, or constituting a part of, a first branch of said at least two branches at the same time as said at least one sliding jaw being fitted to, or constituting a part of, a second branch of said at least two branches.

Prior Art

EP, B1 , 0 014 461 shows a bending device for metal pipes. A cylinder segment 10 having a groove 11 and a shaft 14 works as a bending former around which a metal pipe can be bent. No pipe-positioning index is found on the former.

Summary of the Invention

A first object of the present invention is to provide a tool for pipe bending that is easier to use than known tools of the corresponding type. A second object is to provide a tool for pipe bending that makes it possible to work with greater precision than what is possible with known tools of the corresponding type. A third object is to provide a tool for pipe bending that comprises a former that has a pipe- positioning index. A fourth object is to provide a former that has a pipe-positioning index. Thus, the invention embraces a tool for pipe bending comprising at least two branches, intended to be gripped and pressed together by an operator upon pipe bending, at least one link arm, at least one former, and at least one sliding jaw, said at least one former and said at least one sliding jaw being intended to be placed on either side of a pipe to be bent, and said at least one former being fitted to, or constituting a part of, a first branch of said at least two branches at the same time as said at least one sliding jaw being fitted to, or constituting a part of, a second branch of said at least two branches. At least one of said at least one former has at least one pipe-positioning index, one of which is intended to be placed as close as possible to a corresponding bending-measure index on the pipe when the pipe is placed in the tool in order to be bent.

When the pipe has been placed in the tool in order to be bent, the substancially perpendicular distance, before bending, between, on one hand, a plane through said pipe-positioning index as well as through said bending- measure index and simultaneously substancially perpendicular to the substancial direction of extension of the pipe and, on the other hand, a first end of the pipe may be substancially equal to the substancially perpendicular distance, after bending, between, on one hand, a plane substancially coincident with a substancially straight centre line in a first part of the pipe and simultaneously substancially perpendicular to the substancial direction of extension of a second part of the pipe and, on the other hand, said first end of the pipe.

When the pipe has been placed in the tool in order to be bent, the substancially perpendicular distance, before bending, between, on one hand, a plane through said pipe-positioning index as well as through said bending- measure index and simultaneously substancially perpendicular to the substancial direction of extension of the pipe and, on the other hand, a second end of the pipe may be substancially equal to the substancially perpendicular distance, after bending, between, on one hand, a plane substancially coincident with a substancially straight centre line in a second part of the pipe and simultaneously substancially perpendicular to the substancial direction of extension of a first part of the pipe and, on the other hand, said second end of the pipe.

Said at least one former may have at least one start index. Said at least one start index may be a part of at least one scale graduated in angular degrees. Said former may have at least one finely graduated overbending index. Said at least one overbending index may correspond to a pipe bending of approx. 91-93°, preferably approx. 93°.

Said at least one sliding jaw may have at least one start index. Said at least one sliding jaw may have at least one pipe-positioning index. Said first branch may have at least one holder-on for pipes that are being bent. Said first branch may have at least one part protruding from the tool and respectively provided with at least two basically plane-parallel sides suitable for vice attachment. Said at least one former may have the shape of a modified cylinder segment, the periphery of which has at least one groove for the receipt of said pipe to be bent, and the centre of which has at least a first shaft having a direction of extension that is substancially perpendicular to a substancial plane of extension of said modified cylinder segment. Said at least one groove may extend alongside said periphery along at least one semicircle in a substancial plane of extension of said modified cylinder segment. Said at least one first shaft may, in at least one corresponding first mounting, pivotably unite said at least one former and said at least one link arm. At least one second shaft may, in at least one corresponding second mounting, pivotably unite said at least one link arm and said second branch.

Said at least one former may, in a part that is situated between said at least one groove and said at least one first shaft, have at least one clearance in the form of at least one through hole. Said at least two branches may be curved in the ends thereof being most distant from said at least one former. Said at least two branches may be curved in different directions. Said at least two branches may be curved inwards towards each other. At least one of said at least two branches may have at least one transport locking device in the form of at least one strap that forms at least one loop.

Thus, the invention also embraces a former for use as a part of a tool for pipe bending, said tool, in addition to at least one former, comprising at least two branches, intended to be gripped and pressed together by an operator upon pipe bending, at least one link arm, and at least one sliding jaw, said at least one former and said at least one sliding jaw being intended to be placed on either side of a pipe to be bent, and said at least one former being fitted to, or constituting a part of, a first branch of said at least two branches at the same time as said at least one sliding jaw being fitted to, or constituting a part of, a second branch of said at least two branches. The former has at least one pipe-positioning index, one of which is intended to be placed as close as possible to a corresponding bending- measure index on the pipe when the pipe is placed in the tool in order to be bent.

When the pipe has been placed in the tool in order to be bent, the substancially perpendicular distance, before bending, between, on one hand, a plane through said pipe-positioning index as well as through said bending- measure index and simultaneously substantially perpendicular to the substancial direction of extension of the pipe and, on the other hand, a first end of the pipe may be substantially equal to the substantially perpendicular distance, after bending, between, on one hand, a plane substantially coincident with a substantially straight centre line in a first part of the pipe and simultaneously substantially perpendicular to the substancial direction of extension of a second part of the pipe and, on the other hand, said first end of the pipe.

When the pipe has been placed in the tool in order to be bent, the substantially perpendicular distance, before bending, between, on one hand, a plane through said pipe-positioning index as well as through said bending- measure index and simultaneously substantially perpendicular to the substancial direction of extension of the pipe and, on the other hand, a second end of the pipe may be substantially equal to the substantially perpendicular distance, after bending, between, on one hand, a plane substantially coincident with a substantially straight centre line in a second part of the pipe and simultaneously substantially perpendicular to the substancial direction of extension of a first part of the pipe and, on the other hand, said second end of the pipe.

The former may have at least one start index. Said at least one start index may be a part of at least one scale graduated in angular degrees. The former may have at least one finely graduated overbending index. Said at least one overbending index may correspond to a pipe bending of approx. 91-93°, preferably approx. 93°.

List of Figures Figure 1 shows, in a perspective view, a tool for pipe bending according to the invention.

Figure 2 shows, in a view straight from above, the tool of Figure 1.

Figure 3 shows, in a side view from the left, the tool of Figure 1.

Figure 4 shows, in a side view from the right, the tool of Figure 1. Figure 5 shows, in a view straight from below, the tool of Figure 1.

Figure 6 shows, in a view straight from above, a part of the tool of Figure 1 with a pipe before bending.

Figure 7 shows, in a view straight from above, a part of the tool of Figure 1 with a pipe after bending. Description of Embodiments

The tool in its entirety is seen in the Figures 1-5. A first branch 1 having a handle part 2 and a second branch 3 having a handle part 4 are intended to be gripped by an operator. The first branch 1 shows, in the end being most distant from the operator, an holder-on 5, a part 6 for vice attachment, and a former 7. The second branch 3 shows, in the end being most distant from the operator, a link arm 8 and a sliding jaw 9. A first shaft 10 in a corresponding first mounting in the former 7 and/or the link arm 8 pivotably unites the former 7 and the link arm 8. A second shaft 11 in a corresponding second mounting in the link arm 8 and/or the second branch 3 pivotably unites the link arm 8 and the second branch 3.

Simultaneously, the presence of the shafts 10, 11 means that the first branch 1 is pivotably united to the second branch 3 and that the tool can be manoeuvred by an operator having a branch 1 , 3 in each hand.

The branches 1 , 3 are substancially straight except in the handle parts 2, 4 where they, in the ends thereof being closest to the operator, are bent inwards towards each other. This means that the tool is more comfortable to handle in the open state, when the handle parts 2, 4 are far from each other, than the tool would be if the handle parts 2, 4 were straight. The branches 1 , 3 are made of pipes of metal, such as steel or the like, and the pipes also extend substancially through the handle parts 2, 4 but the surface layer of the handle parts 2, 4 consists of a substancially soft elastomer or the like.

It is naturally also conceivable that each one of said pipes instead extends through only a part of the corresponding handle part 2, 4 or not at all extends through the corresponding handle part 2, 4. The two pipes may also be differently long and extend differently far through the respective corresponding handle part, the elastomer or another suitable material making up so that the branches 1 , 3 become substancially equally long.

On the first handle part 2, there is a transport locking device 2a, see Figure 5, in the form of a strap that forms at least one loop. If the loop is threaded over the second handle part 4, the handle parts 2, 4 and thereby also the branches 1 , 3 are kept well together during transportation of the tool. The strap of the transport locking device is deflectable and flexible and manufactured from elastic textile, rubber or the like. The holder-on 5 has a curved hook-like shape, see particularly Figures 3 and 4, to be able to retain a pipe 12 in connection with a bending operation. With the concept bending ("bockning") the same as bending ("bόjning") is here meant and as a result of the operation, a pipe bend is obtained. The part 6 for vice attachment protrudes from the tool and is provided with two substancially plane- parallel sides 13, 14 suitable for vice attachment.

The former 7 has the shape of a modified cylinder segment, the periphery of which has a groove 15 for the receipt of said pipe 12 to be bent. The groove 15 extends alongside said periphery along at least a semicircle in a substancial plane of extension of said modified cylinder segment, which plane of extension is parallel to the plane of the paper in the Figures 2 and 5-7. This semicircle shows a first radius corresponding to the perpendicular distance between the bottom of the groove 15 and the centre of the shaft 10, which first radius should be chosen in view of the dimension of the pipe 12 to be bent, the radius being chosen to be approx. 37-47 mm, preferably approx. 42 mm for pipe dimension 12, and approx. 50-60 mm, preferably approx. 55 mm for pipe dimension 15. As a broad, general rule of thumb in relation to the measures mentioned above, it may be mentioned that said first radius should be smaller than or possibly equal to four times the diameter of the pipe 12. Said first radius corresponds directly to the resulting bending radius of the pipe 12.

Furthermore, the groove 15 shows, in a section perpendicular to the substancial length extension thereof, a substancially semicircular shape having a second radius that should correspond to the cross-sectional radius of the pipe 12 and that accordingly also should be chosen in view of the dimension of the pipe 12 to be bent. The entire former 7 is easily replaceable on the tool, and therefore a former having suitable measures of occurring radii can be used for each one of the normally occurring pipe dimensions. The former 7 is fitted to the branch 1 by means of a screw, a pin on the branch 1 simultaneously meeting a corresponding hole in the former 7 to prevent the former 7 from rotating around the screw when the tool is used. The described arrangement is only an example and the corresponding functions may be obtained in any other known way.

The web part of the former 7, i.e., the part between the groove 15 and the first shaft 10, is, in comparison with surrounding parts, thin and furthermore broken up with a plurality of through holes 16 of varying shapes. In addition, the former 7 is provided with a scale 17 graduated in angular degrees from 0° to 180°, the degree values of 0, 45, 90, 135 and 180 having been marked particularly by the fact that not only scale lines are present for said degree values but also by the fact that the degree values are written numerically. Scale lines and numerals are recessed in the surface of the scale 17 and marked with a colour deviating from the rest of the surface. In addition, a pipe-positioning index 18 and a pipe- positioning index 19 are present, which are located along an imaginary, basically straight, line starting from an imaginary extension of the marking for 0° on the scale 17, the pipe-positioning index 18 being located closer than the pipe- positioning index 19 to the marking for 0° on the scale 17, and said line extending substancially parallel to each pipe piece 12 properly placed in the tool in order to be bent. The former 7 also shows five particular overbending indexes 20. In addition, an extra handle part/thumb-grip part (not shown) may be present on the former 7. The sliding jaw 9 is attached to the second branch 3 by two pins 21 of a suitable type, e.g., tension pins 21. The sliding jaw 9 is made of polymer material or the like and provided with a start index 22 and two pipe-positioning indexes 23, 24. Also the sliding jaw 9 shows a groove 25 for the receipt of said pipe 12 to be bent. The groove 25 extends along the entire length of the sliding jaw 9 and shows, in a section perpendicular to the substancial length extension thereof, a substancially semicircular shape having a third radius that should correspond to the cross-section radius of the pipe 12 and that accordingly also should be chosen in view of the dimension of the pipe 12 to be bent. It may also be a modified semicircular shape. The sliding jaw 9 is also easily replaceable on the tool, and therefore a sliding jaw having a suitable measure of occurring radius can be used for each one of the normally occurring pipe dimensions.

The holder-on 5, the part 6 for vice attachment, the link arm 8 and the end of the second branch 3, closest to the shaft 11 , are manufactured from forged steel or the like. The shafts 10, 11 are manufactured from steel or the like and the former 7 is manufactured from aluminium or the like. The materials mentioned in this description are without exception to be seen as examples. Thus, the branches 1 , 3 may, in addition to steel, be made of a number of alternative known materials, such as, for instance, another metal, light metal, composite and/or plastic, and the same applies to the holder-on 5, the part 6 for vice attachment, the link arm 8 and the shafts 10, 11. Correspondingly, the former 7 may, in addition to aluminium, be made of a number of alternative known materials, such as, for instance, another light metal, metal, composite and/or plastic. The sliding jaw 9 may, in addition to polymer material, be made of a number of alternative known materials, such as, for instance, metal, ceramic and/or composite.

Now, here it will be described briefly how to proceed upon bending of a pipe/pipe piece by means of the tool according to the invention. First, the operator checks that each one of the former 7 present on the tool and the sliding jaw 9 likewise present on the tool has dimensions adapted for the pipe 12 in question, i.e., that said first, second and third radii are correct in view of the pipe dimension of the pipe 12. Next, the operator opens the tool by gripping the handle parts 2, 4 and space them apart from each other. The pipe 12, suitably in the form of a pipe piece 12 having an index for a bending measure of the pipe bend intended to be produced, is placed in the tool in such a way that the pipe 12 will rest in the groove 15 and simultaneously be positioned in the holder-on 5 in the hook-shaped end part thereof. Said bending measure constitutes, for the pipe bend intended to be produced and as for a bending of approx. 90°, a substancially perpendicular distance between an end of the pipe 12 and a plane that substancially coincides with a substancially straight centre line in a first part of the pipe 12, which plane simultaneously extends substancially perpendicularly to the substancial direction of extension of a second part of the pipe 12, said first and second parts of the pipe 12 constituting a straight branch each included in the pipe bend. With the expression "a plane substancially coincident with a substancially straight centre line", here is meant a plane that intersects the centre line and simultaneously extends substancially parallel to the same, i.e., the centre line lies entirely in the plane. With the expression "centre line", here is meant a line that interconnects the circle centres in each cross-section of the pipe 12. If said bending measure has been given starting from the left of the pipe piece 12, when the operator holds the same in front of him basically horizontally, said bending-measure index is placed right opposite said pipe-positioning index 19 of the former 7. However, if said bending measure has been given starting from the right of the pipe piece 12, said bending-measure index is placed right opposite said pipe-positioning index 18 of the former 7. The operator then gently brings together the branches 1 , 3 until the sliding jaw 9, along the entire length thereof, abuts against the pipe 12 and this, accordingly, is situated in the groove 25 and fills up the same entirely or at least to the greater extent. In general, it applies that the better the abutment of the pipe 12 in the grooves 15, 25 is, the smaller is the risk of undesired deformation of the pipe 12 in connection with bending. The operator checks that the start index 22 on the sliding jaw 9 is right opposite the start index 17a for 0° on the scale 17 of the former 7. For analogous reasons, it then follows that the pipe-positioning index 23 on the sliding jaw 9 is right opposite the pipe-positioning index 18 on the former 7, and the pipe-positioning index 24 on the sliding jaw 9 is right opposite the pipe- positioning index 19 on the former 7. The operator has now allowed the tool with the pipe piece assume the position before bending that is seen in Figure 6. After this, the proper bending of the pipe 12 is carried out, the operator bringing together the branches 1 , 3 using a greater force in a continuous motion, the sliding jaw 9 sliding on the pipe 12 and pressing the same against the former 7 until the desired bending angle has been attained. In each moment, the attained bending angle is given by the degree-value marking on the scale 17 where the start index 22 on the sliding jaw 9 is. However, often one has to allow for a certain springback of the pipe material, which means that overbending should be made, i.e., bend a little more than exactly to the desired bending angle, in order to really obtain the same. Here the overbending indexes 20 will be useful, which mark overbending by 3, 6, 9, 12 and 15° over 90° respectively. Thus, if the operator knows the material of the pipe 12 well and the properties thereof upon bending and, for instance, knows that an overbending to 93° gives a completed bend of 90°, he continues to bring the branches 1 , 3 together until the start index 22 on the sliding jaw 9 reaches up to a position where it is right opposite the first overbending index 20 as counted from the marking for 90° on the scale 17. In Figure 7, an overbending to 96° is shown. After completed bending, the operator opens the tool by spacing apart the handle parts 2, 4 from each other, and then the completed pipe bend can be lifted away. It is of course possible to have overbending indexes at other angular degree values on the scale 17 than the ones given here, for instance, at approx. 3 and/or approx. 6 and/or approx. 9 and/or approx. 12 and/or approx. 15° over 45° for the production of bends having bending angles of this size or over any other degree value. Said angular degree values are the ones preferred, but overbending indexes in the intervals of approx. 1-3 and/or approx. 4-6 and/or approx. 7-9 and/or approx. 10-12 and/or approx. 13-15° over 45°, or over any other degree value, are also possible.

The tool according to the invention shows, among other things, the following advantages. The handle parts 2, 4 are patterned and made with large diameter and bent shape to afford the operator a good grip. The branches 1 , 3 are longer than usual, so that less force than usual should be needed upon bending. Occurring start and pipe-positioning indexes on the former 7 and the sliding jaw 9 and a large opening between the former 7 and the holder-on 5 makes it easy to quickly place the pipe 12 to be bent in the proper position. By the fact that the sliding jaw 9 is of polymer material, the pipe 12 is not scratched upon bending. The scale 17 is easily read since the markings and the numerals are clearly made, recessed and have a deviating colour, and the same applies to occurring start, pipe-positioning and overbending indexes on the former 7 and the sliding jaw 9. The special part 6 for vice attachment means a simple mounting in this way. The particular transport locking device 2a facilitates transportation and storing of the tool.

The invention is not limited to the embodiments shown herein, but may be varied within the scope of the subsequent claims.

Claims

1. Tool for pipe bending comprising at least two branches (1 , 3), intended to be gripped and pressed together by an operator upon pipe bending, at least one link arm (8), at least one former (7), and at least one sliding jaw (9), said at least one former (7) and said at least one sliding jaw (9) being intended to be placed on either side of a pipe (12) to be bent, and said at least one former (7) being fitted to, or constituting a part of, a first branch (1 ) of said at least two branches (1 , 3) at the same time as said at least one sliding jaw (9) being fitted to, or constituting a part of, a second branch (3) of said at least two branches (1 , 3), characterized in that at least one of said at least one former (7) has at least one pipe-positioning index (18, 19), one of which is intended to be placed as close as possible to a corresponding bending-measure index on the pipe (12) when the pipe (12) is placed in the tool in order to be bent.

2. Tool for pipe bending according to claim 1 , wherein, when the pipe (12) has been placed in the tool in order to be bent, the substancially perpendicular distance, before bending, between, on one hand, a plane through said pipe-positioning index (19) as well as through said bending-measure index and simultaneously substancially perpendicular to the substancial direction of extension of the pipe (12) and, on the other hand, a first end of the pipe (12) is substancially equal to the substancially perpendicular distance, after bending, between, on one hand, a plane substancially coincident with a substancially straight centre line in a first part of the pipe (12) and simultaneously substancially perpendicular to the substancial direction of extension of a second part of the pipe (12) and, on the other hand, said first end of the pipe (12).

3. Tool for pipe bending according to claim 1 , wherein, when the pipe (12) has been placed in the tool in order to be bent, the substancially perpendicular dis- tance, before bending, between, on one hand, a plane through said pipe-positioning index (18) as well as through said bending-measure index and simultaneously substancially perpendicular to the substancial direction of extension of the pipe (12) and, on the other hand, a second end of the pipe (12) is substancially equal to the substancially perpendicular distance, after bending, between, on one hand, a plane substantially coincident with a substantially straight centre line in a second part of the pipe (12) and simultaneously substantially perpendicular to the substantial direction of extension of a first part of the pipe (12) and, on the other hand, said second end of the pipe (12).

4. Tool for pipe bending according to any one of the preceding claims, wherein said at least one former (7) has at least one start index (17a).

5. Tool for pipe bending according to claim 4, wherein said at least one start index (17a) constitutes a part of at least one scale (17) graduated in angular degrees.

6. Tool for pipe bending according to any one of the preceding claims, wherein said former (7) has at least one finely graduated overbending index (20).

7. Tool for pipe bending according to claim 6, wherein said at least one over- bending index (20) corresponds to a pipe bending of approx. 91-93°, preferably approx. 93°.

8. Tool for pipe bending according to any one of the preceding claims, wherein said at least one sliding jaw (9) has at least one start index (22).

9. Tool for pipe bending according to any one of the preceding claims, wherein said at least one sliding jaw (9) has at least one pipe-positioning index (23, 24).

10. Tool for pipe bending according to any one of the preceding claims, wherein said first branch (1 ) has at least one holder-on (5) for pipes (12) that are being bent.

11. Tool for pipe bending according to any one of the preceding claims, wherein said first branch (1) has at least one part (6) protruding from the tool and respectively provided with at least two substantially plane-parallel sides (13, 14) suitable for vice attachment.

12. Tool for pipe bending according to any one of the preceding claims, wherein said at least one former (7) has the shape of a modified cylinder segment, the periphery of which shows at least one groove (15) for the receipt of said pipe (12) to be bent, and the centre of which shows at least a first shaft (10) having a direction of extension that is substancially perpendicular to a substancial plane of extension of said modified cylinder segment.

13. Tool for pipe bending according to claim 12, wherein said at least one groove (15) extends alongside said periphery along at least one semicircle in a substancial plane of extension of said modified cylinder segment.

14. Tool for pipe bending according to any one of the claims 12 and/or 13, wherein said at least one first shaft (10), in at least one corresponding first mount- ing, pivotably unites said at least one former (7) and said at least one link arm (8).

15. Tool for pipe bending according to any one of the preceding claims, wherein at least one second shaft (11 ), in at least one corresponding second mounting, pivotably unites said at least one link arm (8) and said second branch (3).

16. Tool for pipe bending according to any one of the preceding claims, wherein said at least one former (7), in a part that is situated between said at least one groove (15) and said at least one first shaft (10), has at least one clearance (16) in the form of at least one through hole (16).

17. Tool for pipe bending according to any one of the preceding claims, wherein said at least two branches (1 , 3) are curved in the ends thereof being most distant from said at least one former (7).

18. Tool for pipe bending according to claim 15, wherein said at least two branches (1 , 3) are curved in different directions.

19. Tool for pipe bending according to any one of the claims 17 and/or 18, wherein said at least two branches (1 , 3) are curved inwards towards each other.

20. Tool for pipe bending according to any one of the preceding claims, wherein at least one of said at least two branches (1 , 3) has at least one transport locking device (2a) in the form of at least one strap (2a) that forms at least one loop.

21. Former (7) for use as a part of a tool for pipe bending, said tool, in addition to at least one former (7), comprising at least two branches (1 , 3), intended to be gripped and pressed together by an operator upon pipe bending, at least one link arm (8), and at least one sliding jaw (9), said at least one former (7) and said at least one sliding jaw (9) being intended to be placed on either side of a pipe (12) to be bent, and said at least one former (7) being fitted to, or constituting a part of, a first branch (1 ) of said at least two branches (1 , 3) at the same time as said at least one sliding jaw (9) being fitted to, or constituting a part of, a second branch (3) of said at least two branches (1 , 3), characterized by at least one pipe- positioning index (18, 19), one of which is intended to be placed as close as possible to a corresponding bending-measure index on the pipe (12) when the pipe (12) is placed in the tool in order to be bent.

22. Former according to claim 21 , wherein, when the pipe (12) has been placed in the tool in order to be bent, the substancially perpendicular distance, before bending, between, on one hand, a plane through said pipe-positioning index (19) as well as through said bending-measure index and simultaneously substancially perpendicular to the substancial direction of extension of the pipe (12) and, on the other hand, a first end of the pipe (12) is substancially equal to the substancially perpendicular distance, after bending, between, on one hand, a plane substancially coincident with a substancially straight centre line in a first part of the pipe (12) and simultaneously substancially perpendicular to the substancial direction of extension of a second part of the pipe (12) and, on the other hand, said first end of the pipe (12).

23. Former according to claim 21 , wherein, when the pipe (12) has been placed in the tool in order to be bent, the substantially perpendicular distance, before bending, between, on one hand, a plane through said pipe-positioning index (18) as well as through said bending-measure index and simultaneously substantially perpendicular to the substantial direction of extension of the pipe (12) and, on the other hand, a second end of the pipe (12) is substantially equal to the substantially perpendicular distance, after bending, between, on one hand, a plane substantially coincident with a substantially straight centre line in a second part of the pipe (12) and simultaneously substantially perpendicular to the substancial direction of extension of a first part of the pipe (12) and, on the other hand, said second end of the pipe (12).

24. Former according to any one of the claims 21-23, which has at least one start index (17a).

25. Former according to claim 24, wherein said at least one start index (17a) constitutes a part of at least one scale (17) graduated in angular degrees.

26. Former according to any one of the claims 21-25, which has at least one finely graduated overbending index (20).

27. Former according to claim 26, wherein said at least one overbending index (20) corresponds to a pipe bending of approx. 91-93°, preferably approx. 93°.