Method and Bending Machine for Bending Bar-Shaped Material

Field of the Invention

The present invention concerns a method for bending bar-shaped material in a bending machine, where a bar material may be fed to a bending tool by means of feeding means and bent into elements by means of the bending tool and where the bar material is acted on magnetically in direction towards the bending machine at least during part of the bending operation. The bending tool may optionally consist of a bending core with a central bar channel and a bolt spaced apart from its centre, mounted on the bending disc or a bending arm, with a bending roller rotatably suspended thereon. Alternatively, the bending tool may include a bending mandrel and a bending roller mounted on a bending disc or a bending arm. The bar-shaped material may optionally be retained by a clamping means during the bending operation. The bar material may e.g. be rods for reinforcing concrete. By bar-shaped material or bar material in the present application is meant material that may be provided from a storage in the form of rods or a storage in the form of a coil.

The invention furthermore concerns a bending machine for bending bar-shaped material, where a bar material may be fed to a bending tool by means of feeding means and bent into elements by means of the bending tool and where at least one magnetic means is fitted in the bending machine for magnetically acting on the bar material, which is to be bent in the bending tool, in direction towards the bending machine at least during part of the bending operation. The bending tool may optionally consist of a bending core with a central bar channel and a bolt spaced apart from its centre, mounted on a bending disc or bending arm, with a bending roller rotatably suspended thereon. Alternatively, the bending tool may include a bending mandrel and a bending roller mounted on a bending disc or a bending arm. The bar-shaped material may optionally be retained by a clamping means during the bending operation.

Background of the Invention

There is known, e.g. from FR-Al -2 715 334, EP-Al-I 199 115, EP-A2-1 002 592 or WO 2005/061144 Al, a bending tool with a rotatable bending disc that has a non- rotatable bending core at its centre. Spaced apart from the centre of the bending core, the bending disc carries a bolt with a bending roller rotatably journalled thereon and which

may be pivoted by the rotatable bending disc about its centre for performing a predefined bending operation for bending elements in the form of one or more rods. The rods may be held fixed during the bending operation by clamping jaws provided outside the bending disc.

A drawback of the art thus known is that the bar material can have ribs and ovalities which entail a risk of the bar material turning or twisting or tilting in the bending itself during the bending operation, so that there is a risk of the bar material swinging out from the intended bending plane and thereby also from the bending machine so that the bent element appears with incorrect bending.

Also, an operator may risk injury. In practice, one may therefore often perform the bending by letting the operator hold the element while bending the material. While the bar material is bent, yield stresses occur in the metal, and the bar material will then be retained in its bent shape.

From DE 10357156 and GB 689980 there are know bending systems as discussed above. In these systems, permanent magnets or electromagnets are used for retaining bar material or sheet material during a bending operation. There is no mentioning of controlling retention force and/or need to make allowance for changes in length during the bending operation.

Thus there is a need for and wish to enable performing the bending in a more secure way, both for the sake of the bending itself and with regard to the working environment of the operator.

Object of the Invention

It is the purpose of the invention to provide a method and a bending machine that enables reducing or preventing the risk of the bar material swinging out from the bending plantøfaending machine during the bending.

Description of the Invention

This purpose is achieved by the said method which is peculiar in that the bar material is acted on magnetically in direction towards the bending machine at least during part of the bending operation.

The bending machine according to the invention is peculiar in that the magnetic force and the strength of clamping means are adapted so that the bar material may slide in relation to the bending tool during the bending operation.

As magnetic means are disposed in immediate vicinity or on the bending tool itself, it will be possible to draw magnetic bar material against the bending disc during the bending and to prevent it from pivoting outwards away from the bending machine and out of the intended bending plane. Hereby, there is no need for the operator to hold the bar material and there will not be any risk of faulty bending.

There is applied a magnetic action that together with the action of the bending tool/clamping means allow the bar material to slide in relation to the bending tool during the bending operation. Sliding will be necessary with regard to the changes in length that may occur in the bar material during the bending. Therefore, it is expedient to arrange the magnetic force in a way so that the sliding is possible. Such magnetic force may easily be established by using a control unit controlling electromagnets. Alternatively, permanent magnets may be used and displaced with greater or lesser spacing from the rod material in order thereby to vary the magnetic force with which the bar material is to be acted on.

In a preferred embodiment, the method according to the invention may be peculiar in that electromagnetic action is applied.

By using electromagnets, it will be possible in a relatively easy way to vary the strength, as well as it will also be possible to initiate or stop the magnetic action on the bar material. This may be effected by using a control unit which, besides on/off-function, may also have a function for adjusting the current intensity for the electromagnets.

Moreover, it is noted that according to the invention there may be provided one or more magnets, depending on the size of the bar material to be bent. Also, the number and disposition of magnetic means can depend on the way in which bending is to be performed. One or more magnets may thus be disposed upstream or downstream of the bending tool and/clamping means which retain the bar material in the bar channel of a bending machine. The magnetic means may be disposed at fixed positions behind the machine, or be disposed movably, e.g. so that they are moved synchronously with the rotation of the bending disc/bending arm.

Also, it will be possible to apply the magnetic action in an initial phase and the bending operation, and then to remove the magnetic action. In this way there is used a magnetic action which is variable during the course of the bending. After performing the bending, and the bar material is in contact with the bending tool, the need for holding bar material against a surface on bending disc, bending arm or bending machine may be reduced.

Description of the Drawing

The invention will now be explained more closely in the following with reference to the accompanying schematic drawing, where:

Fig. 1 shows a first embodiment of a bending tool in a bending machine according to the invention, as seen from the side; Fig. 2 views of the tool shown in Fig. 1, as seen from above;

Fig. 3 a view corresponding to Fig. 1 where the first bending operation is initiated;

Fig. 4 views of the tool shown in Fig. 3, as seen from above;

Fig. 5 a view corresponding to Fig. 1 where the second bending operation is initiated; Fig. 6 views of the tool shown in Fig. 5, as seen from above;

Fig. 7 shows a second embodiment of a bending tool in a bending machine according to the invention, as seen from the side, and where the first bending operation is initiated;

Fig. 8 views of the tool shown in Fig. 7, as seen from above; Fig. 9 a view corresponding to Fig. 7 where the second bending operation is terminated; Fig. 10 views of the tool shown in Fig. 9, as seen from above;

Fig. 11 shows a third embodiment of a bending tool according to the invention as seen from the side;

Fig. 12 a view corresponding to Fig. 11 with supplied bar which is held in the bending core of the tool;

Fig. 13 views of the tool shown in Fig. 12, as seen from above;

Fig. 14 a view corresponding to Fig. 12 where the first bending operation is initiated;

Fig. 15 views of the tool shown in Fig. 14, as seen from above;

Fig. 16 shows a fourth embodiment of a bending tool according to the invention, as seen from the side, and in the form of a bar feeding rod with gripper and two clamping elements for feeding the bar end close to the bending core; Fig. 17 views of the tool shown in Fig. 16, as seen from above; Fig. 18 shows a fifth embodiment of a bending tool according to the invention, as seen from the side, and in the form of Fig. 19 shows the tool shown in Fig. 18 with a bar inserted and with beginning counterclockwise bending; and Fig. 20 shows the tool shown in Fig. 18 with a bar inserted and with beginning clockwise bending.

Detailed description of the invention

In connection with the drawing, when speaking of "seen from the side" or "seen from above, there is no limitation to orientation in relation to vertical/horizontal, as bending may occur in a plane at any angle relative to vertical/horizontal orientation.

In Fig. 1 appears a schematic drawing of an example of a bending tool design. It consists of a bending disc rotating about its centre. At the middle of the bending disc there is provided a bending mandrel 2 disposed so that a bar or rod 4 is resting on the surface of the mandrel when the bar 4 is moved into the bending disc 1. Insertion will occur from left to right as indicated with arrow 34 in Fig. 3. A bolt is fastened to the bending disc 1, carrying a bending roller 3 which is rotatable about the bolt. By rotating the bending disc 1, the bending roller 3 will press the rod downwards and cause bending around the bending mandrel 2 as illustrated in Fig. 3. Alternatively, it is possible to displace the

bending mandrel upwards so that the bar is passing down under the bending mandrel 2, and rotate the bending roller from below and upwards to cause upwards directed bending about the bending mandrel.

In Fig. 1, there is schematically illustrated disposition of magnetic means in the form of a series of electromagnets 26 - 32 which are disposed in a semi-circular shape outside the bending core. It appears from Fig. 2 that the magnets are placed with a top side approximately in the same plane as the surface 33 of the bending disc. The magnets will thus be placed very closely to the end of the bar 4 to be bent in order to act on the latter by activating the magnets. Usually, the magnets will lie protected behind a plate (not shown).

In Fig. 2 there is shown only one magnet for the sake of clarity. In situation A, the bar is inserted into the bending tool and placed at a position ready for bending. It appears that the bar 4 may have a curvature so that it is directed away from the surface 33. In situation B, the magnets are activated, and it is seen that the bar is drawn in against the surface 33 so that it will be correctly positioned for subsequent bending. Then the bending may be initiated as illustrated in Fig. 3.

Even if magnets are only illustrated downstream of the bending disc, magnets may also be provided upstream of the bending disc. The retained part of the bar may hereby also be secured during the bending. It is illustrated that the electromagnets are in fixed positions, but it is also possible that the electromagnets, or some of these, may turn together with the bending disc (see e.g. Fig. 7).

In Fig. 3 appears that a first bending is commenced as the bending roller is rotated downwards. The bar 4 is opposite the magnet 30 in the shown position, and will be moved down over the magnets 31 and 32 by continued bending. During the bending there may be a risk of twisting and deflection of the bar 4 from the surface 33 of the bending disc 1. In order to avoid his, the electromagnets are activated while the bending occurs.

In Fig. 4 appears a situation A where the bar is placed in the bending tool during bending in a situation without activating the magnets. It appears that the bar 4 may have a

curvature so that it is directed away from the surface 33. This situation may cause faulty bending of the bar.

In situation B in Fig. 4, the magnets are activated, and it is seen that the bar is drawn in against the surface 33 so that it will be correctly positioned during the bending. It is noted that not all magnets need to be activated during the bending. There may be an individual activation of the magnets so that activation of the magnets only occurs when the bar is disposed opposite the magnets.

In Fig. 5 appears that a second bending has been commenced as the bending roller is rotated downwards, pivoting the bar with a bent end part 35 downwards. The bar 4 is opposite the magnet 30 in the shown position, and will be moved down over the magnets 31 and 32 by continued bending.

In Fig. 6 appears a situation A where the bar is placed in the bending tool during bending in a situation without activating the magnets. It appears that the bar 4 may have a curvature so that it is directed away from the surface 33 and where the extreme end part 35 is directed out of the plane of the bending. This situation may provide faulty bending of the bar, as the first and second bendings may lie in different planes. This is avoided by activating the magnets as shown in situation B in Fig. 6. The magnets are activated here, and it appears that the bar is drawn in against the surface 33 with the extreme end part disposed in the plane in which also the bending of the other end of the bar is performed. The bar will thus be correctly positioned for bending.

In Fig. 7 appears a second embodiment of a bending tool with a bending core 5 consisting of two mutually opposed halves with an interposed bar channel 6 with inserted bar 4, which by mean of the bending roller 3 on the bolt is bent about the contour of the bending core. Due to the turning movement of the bending disc 1 , the bar 4 will tend to be pulled out of the bending core.

In order to avoid this pulling out, clamping jaws 7 are disposed in front of and after the bending disc 1, and Fig. 7 shows such a disposition. The clamping jaws 7 are actuated while the bending takes place and secures the bar 4 under this operation. The rod is advanced by means of drive roller mechanisms 8 or 9. During the bending there may be

a risk of twisting and deflection of the bar 4 from the surface 33 of the bending disc 1. In order to avoid his, the electromagnets are activated while the bending occurs. Here, fewer magnets are shown than in Figs. 1 - 6, but the same number, or more, may be used. Magnets may thus be provided along the entire periphery around the bending tool in order to hold an element in against the bending machine at any angular position around the bending tool.

Furthermore, electromagnets 36 and 37 are shown which are placed in the bending disc 1 and rotated together with the latter. A greater degree of security of retention of the bar during the bending is hereby achieved.

In Fig. 8 appears a situation A where the bar is placed in the bending tool during bending in a situation without activating the magnets. It appears that the bar 4 may have a curvature so that it is directed away from the surface 33. This is avoided by activating the magnets as shown in situation B in Fig. 8.

The clamping jaws 7 and the drive roller mechanisms 8 and 9 may be depressed for avoiding collision with the bent ends of the rod. Some of the geometric conditions for the rods to be bent are given by the distances between respective drive roller mechanisms 8 and 9 and clamping jaws 7. The drive roller mechanism 9 and the clamping jaw 7 at the right side may be countersurik for avoiding collision with the bent part of the rod.

The electromagnets are adapted for variable strength which may be regulated by means of a control unit which may also switch the electromagnets on and off. The magnetic force and the strength of clamping means are adapted so that the bar 4 may slide in relation to the bending tool during the bending operation.

In Fig. 9 appears the end of a second bending operation in which a bar 4 is bent with a 90° bending at each end. As shown on Fig. 9, the bending core may be turned 180°, and the drive roller mechanism at the left side may be countersunk. Besides, it appears that the section 10 of the bar 4, which is situated between the bending core 5 and the clamping jaw 7 and in the clamping jaw itself, is to present a certain minimum length in order for the clamping jaw to hold the bar during the bending operation. Electromagnets

36 - 38 are shown here which are placed in the bending disc 1 and rotated together with the latter. A high degree of safe retention of the bar during the bending is hereby achieved.

In Fig. 10 appears a situation A where the bar is placed in the bending tool without activating the magnets. It appears that the bar 4 may have a curvature so that the bent end parts 35 are directed away from the surface 33. This is avoided by activating the magnets as shown in situation B in Fig. 10.

In Fig. 11 is shown a third embodiment of a bending tool for a bending machine according to the invention and of the type with a clamping jaw in the form of a clamping piston 14, 15 in the bending core 11. The bar material to be bent is clamped after its feeding into the bar channel 18 of the bending core 11 itself for receiving the rod 4. The electromagnets are simultaneously activated.

The bending core 11 is secured against turning and is provided at the centre of a bending disc 12. The bending disc 12 may rotate about the bending core 11. The clamping is effected by means of a steel hardened pressure member 13 which is pressed against the rod by a clamping piston 14 or 15. The bending disc 12 may rotate about the bending core 11.

Fig. 12 shows the bending tool according to Fig. 5 with a bar inserted in the bar channel 18.

In Fig. 13 appears a situation A where the bar 4 is placed in the bending tool without activating the magnets. It appears that the bar 4 may have a curvature so that the end is directed away from the bending disc. This is avoided by activating the magnets as shown in situation B in Fig. 13.

Fig. 14 shows an initiated bending. By turning the bending disc 12, the bolt with the bending roller 16 has bent the bar 4 in an angle. A special procedure for the clamping function and a special shape of the bending core are used. During the bending, one pressing member 13 is pressed by its clamping piston 15 against the side of the bar 4 which is opposite the bending roller 6. Under this unilateral pressing, the rod bears

against a sharp edge 17 on the bending core. This edge and the clamping piston prevent an immediate longitudinal displacement of the rod in the bar channel 18 at the beginning of the bending operation. Activation of the electromagnets will also here ensure that the bar 4 is held in against the surface of the bending disc so that the bending occurs in the intended bending plane.

In Fig. 15 appears a situation A without activating the magnets. It appears that the bar 4 may have a curvature so that the end is directed away from the bending disc. This is avoided by activating the magnets as shown in situation B in Fig. 15.

The two halves of the bending core are each equipped with at least one sharp edge 17 as shown. During a bending operation, the bolt provided at one side of the rod with the bending roller 16 rotatably journalled thereon is to be brought into operation by turning the bending disc. During this operation, the clamping piston 15 incorporated at the opposite side of the rod is brought into function and thereby presses the rod against the sharp edge 17 at the opposite half of the bending core. The rod is thus fixed during the bending operation itself between a sharp edge and one clamping piston.

A fourth embodiment of a bending tool for a bending machine according to the invention is seen in Fig. 16. The tool includes stationary electromagnets 23, 29, 30 and

32 as well as two electromagnets 19 provided in the bending disc 1 and rotating with it.

The tool furthermore includes a gripper 20 with two clamping elements 21 and 22 which are passed in over the bending disc 1 and which clamp the outer end 24 of a bar 4 which has been bent. The free end 25 of the bar is acted on by the magnet 19 during the bending. A very short bar is shown here. It is possible to bend a bar which is so short that the free end 25 is within the bending disc 1 so that the bar is only secured by the rotating electromagnet 19 during the bending. There is one electromagnet 19 at each side of the bending roller 3, as indicated by the appearance of two electromagnets 19. It is optional to have one, two or more electromagnets 19.

In Fig. 17 appears a situation A without activating the magnets. It appears that the bar 4 may have a curvature so that the end is directed away from the bending disc. This is avoided by activating the magnets as shown in situation B in Fig. 17.

A fourth embodiment of the bending tool for a bending machine according to the invention is seen in Figs. 18-20. This embodiment is designed technically simple, as a central pivot bolt 42 is provided in a non-rotatable bending core 11. In this embodiment is schematically illustrated disposition of magnetic means in the form of an electromagnet 28 which is disposed upstream of the two mutually opposed clamping means. Moreover, there are shown two electromagnets 36, 23 disposed downstream of the two mutually opposed clamping means in the bending machine.

The pivot bolt 42 is thus provided at the centre of the bending core 11 and has a groove or slot 41 which can be aligned with the bar channel 18. The pivot bolt 42 may turn in both directions, whereby a rod 4 is brought in contact with opposed contact surfaces 40 and interacting contact surfaces 39 on the bending core. The contact surfaces 40 in the pivot bolt can be made sharp-edged in order to get a function corresponding to the sharp edge 17 which is mentioned above.

Fig. 18 illustrates the bending tool with the slot 41 aligned with the bar channel 18 and without any rod in the tool.

Fig. 19 shows a situation where the rod 4 is provided in clamped position by bending clockwise or to the left as seen into the plane of the paper, and as indicated by arrow in the left side of the drawing. In this situation, the bar 4 is clamped by the marked sharp- edged contact surfaces 40 in the pivot bolt and the marked contact surfaces 39 in the bending core.

In Fig. 20 appears a corresponding clamping by bending clockwise or to the right, as seen against the plane of the paper and as indicated by the arrow at the left side of the Figure. In this situation, the bar 4 will be clamped between the marked sharp-edged contact surfaces 40 in the pivot bolt and the marked contact surfaces 39 in the bending core.

With the embodiment of the bending tool shown in Figs. 18-20, there is no need for separate pistons for clamping the rod 4 during the bending movement. In this embodiment, the rotation itself is applied during bending, as the rotation of the pivot bolt 42 is used at the same time for clamping the rod.

The invention is not at all limited to the embodiments indicated in the present application, as other embodiments may be provided within the scope of the invention.

LIST OF REFERENCE NUMBERS

1 Bending disc

2 Bending mandrel

3 Bending roller (on bolt)

4 Rod

5 Contour of bending core

6 Bar channel

7 Clamping jaws

8 Drive roller mechanism

9 Drive roller mechanism

10 Rod section

11 Bending core

12 Bending disc

13 Pressing member

13, 14 Clamping means/clamping member

13, 15 Clamping means/clamping member

14 Clamping piston

15 Clamping piston

16 Bending roller which is rotatably journalled on a bolt

17 Sharp edge

18 Bar channel

19 Electromagnet

20 Gripper

21 Clamping element

22 Clamping element

23 Electromagnet

24 Outer end (of bar)

25 Free end (of bar)

26 Electromagnet

27 Electromagnet

28 Electromagnet

29 Electromagnet

30 Electromagnet

31 Electromagnet

32 Electromagnet

33 Surface (of bending disc)

34 Arrow (feeding of bar) 35 Bent end part

36 Electromagnet

37 Electromagnet

38 Electromagnet

39 Contact surface 40 Contact surface

41 Groove or slot

42 Central pivot bolt