EP0371960B1 - Method for bending bar-shaped materials - Google Patents

Description

The invention relates to a method for bending rod-shaped materials such as reinforcing steels by means of a bending machine which has at least two bending slides, each with a bending mandrel and a bending crank arranged rotatably around the latter, the rod-shaped material being gripped and bent by the bending slides in such a way that a Section of the material is alternately immovably fixed by one of the bending slides, while the bending sled not holding the material bends the material or is moved along it.

EP-AO 121 896 describes a device for bending rod-shaped materials, which comprises two bending slides, each with a bending dome with an associated bending crank. A section of material is held in place by a bending slide during the bending process. The other bending slide is used to bend. So that the material is not shifted during bending, so that the non-bending bending slide firmly holds the material, it is necessary that the material is already plastically deformed in this section.

A method is known from US Pat. No. 3,803,893 in which material can be deformed by means of two bending slides. In order to hold the material immovably, a section between the bending mandrel and the bending crank of a bending slide is held permanently deformed.

The object of the present invention is to develop a method of the type described in the introduction in such a way that a bending process is possible in which any desired bending shape can be achieved with high accuracy, and in addition to the bending slide, further devices holding the material are not required.

The object is achieved in that for the immovable fixing of the material, a section which interacts with a bending slide and is not bent is bent by an angle α, which leads exclusively to an elastic deformation. In other words, it is proposed according to the invention that the bending slide can also hold rod material when it is still undeformed. This is not possible according to the state of the art. This results in the particular advantage of turning materials to z. B. Z-shapes or modifications of these.

According to the invention, the elastic deformability of the material is taken into account. Accordingly, if the material is bent by an angle α, which does not yet lead to permanent deformation, it is ensured that the material is held securely by the bending slide, so that the other bending slide can be displaced to the required extent and, if necessary, can carry out a plastic deformation. In particular, the angle α, which can also be referred to as the spring-back angle, is added to each setpoint angle, ie to the angle to be bent, in order to ensure that the plastically deformed section also has the desired geometry when the bending slide no longer acts. Accordingly, the angle α should be the angle by which the material is maximally bendable without being plastic Deformation occurs. The angle α is therefore also the spring-back angle.

Another embodiment of the invention is characterized in that when bending a closed bending shape, the material present in the region of a bending dome is raised, e.g. B. via a transfer plate. As a result, the further bending process is not hindered.

Fig. 1

eine Vorrichtung zum Biegen von stabförmigen Materialien in Draufsicht,

Fig. 2

einen Ausschnitt eines Biegeschlittens,

Fig. 3 bis 5

schematische Darstellungen von Biegevorgängen und

Fig. 6 und 7

Biegeformen von Rundstahl.

The invention is explained in more detail below with reference to exemplary embodiments that can be found in the drawing:

Fig. 1

a device for bending rod-shaped materials in plan view,

Fig. 2

a section of a bending slide,

3 to 5

schematic representations of bending processes and

6 and 7

Bending forms of round steel.

In Fig. 1, a bending machine (10) is schematically shown in plan view, which comprises a horizontally lying processing table. In the exemplary embodiment, two bending carriages (14) and (16) are slidably arranged in the longitudinal direction of the processing table, by means of which preferably rod-shaped steel materials (18) to be introduced into the bending machine (10) are to be bent, as described in more detail below. These bars (18) enter the machine from a material store (20), several bars (18) being able to be bent simultaneously by means of the bending slide (14) and (16). The material store (20) can be part of a schematically illustrated processing line, which is arranged between the bending machine (10) and a bar cutting machine. The bending machine (10) can be programmed via a keyboard (24) in order to cold-deform the materials (18) to the desired extent.

It should also be mentioned that the work surface (12) has a vertical or almost vertical slot for receiving several round materials to be arranged one above the other, which is laterally delimited by the bending slides (14) and (16). In addition to the machine (10), a container (26) is also indicated, into which the bent materials (29) can be thrown by hand. Of course, there is also the possibility that an automatic ejection device is integrated in the machine (10).

Finally, counterholders (136) are drawn in in FIG. 1, which prevent bending when the material (18) is bent.

Each bending slide (14) or (16) consists of a bending crank (28), a bending mandrel (30) and a drive (32) and (34). The bending crank (28) moves at a distance around the bending mandrel (30). The materials to be deformed are then located between the bending crank (28) and bending dome (30).

As indicated in Fig. 2, the bending crank (28) comprises an eccentrically mounted roller mandrel (40), which can optionally be rotated about its axis, and which has two opposing threads (42) and (44) in the desired position (infinitely adjustable axial distance bending roller (40), bending mandrel (30)) is fixed immovably, so that the bending mandrel (40) cannot be released regardless of the direction of rotation of the bending crank (28). The bending crank (28) is also received eccentrically by a shaft (46).

If the rotary movement of the bending crank (28) is preferably brought about by means of a hydraulic cylinder, then the translational movement of the bending slide (14) or (16) itself preferably takes place via hydraulic motors (32) and (34) with a rotary output movement.

An essential feature of the invention is that a portion of the material is held between the bending mandrel and the bending crank during the bending process in such a way that when the other bending slide is moved along the material, it cannot move. A corresponding bending process will now be explained in more detail with reference to FIGS. 3 and 5. The individual parts of the bending slide shown are not described in detail. Rather, the bending slide can have a structure as described above.

3 and 4, a rod-shaped material such as. B. reinforcing steel (142) can be bent on both sides with respect to its longitudinal axis. For this purpose, two bending slides (144) and (146) are used, which alternately hold the material (142) precisely in position and bend to the desired extent. First, the bending slide (144) holds the material (142) in position A. Since the material is not yet to be permanently deformed, it is first bent by an angle α. The angle α depends on the rod material. The angle α is so large that the material is only elastically and not plastically deformed. However, since the material is bent by the angle α, the bending mandrel (148) and the bending crank (150) are clamped, in the broken line of position A. The bending slide (146), which can also be referred to as a bending stick is in position Z. If the end of the material (142) is now to be bent by the angle β, the bending crank (152) is rotated around the bending mandrel (154) of the bending rod (146) by the angle β + α, wherein the angle α corresponds to the angle by which the material springs back when the bending crank (152) no longer acts on the material (142) in the region of the end.

If the first bending process (position Z) has previously been described in such a way that the material (142) has bent by the angle α during the bending of the bending slide (144), the elastic deformation can of course occur after the beginning of the bending process by the bending slide (146) be lifted, ie the bending crank (150) returns to the basic position (solid line). It is important, however, that at least at Moving one of the bending slides the other clamps the material.

In order to bend the left end of the material (142) again in a position Y to the desired extent, the material (142) is clamped again by the bending stick (144) (ie bending by the angle α). As soon as the position Y is reached, the bending stick (144) can open again to release the clamping. The bending stick (146) then bends the material (142) again in the Y position. The bending stick (144) should only finally release the clamping when the bending stick (146) has already started the bending process to ensure that the material (142) cannot be moved along its longitudinal axis during the bending.

Uni to initiate a further bending process in such a way that the end gripped by the bending slide (144) is bent in the opposite direction than the opposite end, the bending slide (146) is shifted to position X. Here, the bending carriage (144) clamps the material (142) again. The rod (142) is then turned through 180 °. The bending slides (146) and (144) must release the material. Now the bending slide (144) should bend the associated end. Accordingly, the bending stick (146) elastically clamps the material (142) (bending by the angle α) in order to then rotate the bending crank (150) around the bending mandrel (148) to the desired extent. The angle of rotation is equal to the desired angle α which corresponds to the angle at which there is only elastic but no plastic deformation of the material. As soon as the bending process in position A is complete, the bending slide (146) clamps the material (142) in position X. Then the bending slide (144) is moved to position B. As soon as the bending process begins in position B, the bending slide (146) can release the clamping.

3 and 4 it is clear that without deformation of the material it is necessary that each bending slide (144) or (146) can clamp the rod material (142) by taking advantage of the elastic property of the material. The clamping takes place at least when one of the bending slides (144) or (146) moves along the material (142).

A further bending process can be seen from FIG. 5, which is carried out via bending slides or bending sticks (156) and (158). Here too, at least when a bending slide (156) or (158) is moved, the other bending slide (158) or (156) is in a clamping position. The material (160) to be deformed is bent between the bending slides (156) and (158) (broken line). This makes it apparent that, in order to rule out any distortion in length, the clamping is only to be carried out during the process, whereas the clamping position is canceled during the bending so that the carriage carrying out the bending process can bend the material at the point corresponding to the actual length. Otherwise it would be necessary to arrange counterholders along the length of the material (160), but this would prevent free movement of the bending slides (156) and (158).

6 takes place as follows:
First of all, the rod material (160) is plastically deformed in position C of the bending slide (156) and in position W of the bending slide (158). Then the bending carriage (158) clamps the rod material (160) so that the bending carriage (156) can move into position D. The material (160) is bent during the process. During the bending process in position D, however, the clamping action of the bending carriage (158) is released, so that the material (160) assumes the position that is indicated by the solid line. After bending in position D, the material (160) is clamped again by the bending slide (158). The carriage (156) is then moved to position E. In this position, too a bending process. Finally, the carriage (156) is moved to position F with material (160) clamped by the bending carriage (158) to enable the final bending process. All bending processes take place at an actual angle = target angle (the angle by which the end material should be bent) minus angle α (the angle at which the material is not yet plastically deformable). (The angle α can be programmed into a bending machine, depending on the materials to be bent and their dimensions).

The filled or open rectangles drawn in the bending slide (156) and (158) above the material (160) represent the counterholders (136) shown in FIG. 1, which are intended to prevent the material (160) from bending during bending. These counterholders are attached to the bending slide so that they cannot represent any hindrance when they are moved.

In general, it can be said about the method according to the invention that for the first time without additional complex aids such. B. hydraulically operated clamping elements and without the material to be deformed being plastically deformed, any bends can be made with just two bending slides, the material itself can optionally be rotated about its longitudinal axis. This ensures that when moving a bending slide, the material itself is held firmly and can still be rotated as desired after the process.

It is illustrated with the aid of FIG. 3 that the rod material (142) can no longer be displaced in length in its elastic deformation due to the interaction between the bending roller (150) and the bending mandrel (148). As soon as the rod material (142) has been bent by the angle α, the counterforces caused by the bending roller (150) around the bending mandrel (148) together with the coefficient of friction of the rod material (142) are sufficient to prevent the material from being displaceable in length; because otherwise the force acting in the longitudinal direction would not only have to be overcome forces caused by the above-mentioned elements in addition to frictional forces, but also continuously bend the material so that it can slide out of the area between the bending crank (150) and bending mandrel (148), in both directions. The angle α (clamping angle) is selected so that the material is only elastically and not plastically deformed, ie that when the bending crank (150) is moved back the material is moved back to its starting position.

It should also be mentioned again that the rectangles shown in the figures in the area of the bending slide (146) or (144) above the material (142) are completely filled (in the area of the bending slide (144), in the area of the two right-hand bending slides (146 ) not filled) serve as counter bearings, which ensure that when the material is bent, the rod (142) cannot be bent between the bending slides.

6 and 7 show various bending shapes of round steel, which can be achieved using the teaching according to the invention. A great variety can be seen, although it should be noted that the accuracy of the end products is very high, so that the ejection of the cold-formed materials which are not to be used is extremely low.

Claims (5)

1. Method for bending bar-shaped materials (18, 142, 160) such as reinforcing steels (30, 148, 54) by means of a bending machine (10), which has at least two bending carriages (14, 16, 144, 146, 156, 158), each with a bending block and a bending crank (28, 150, 152) arranged pivoted about said bending block, the bar-shaped material being alternately held immovably by one of the bending carriages while the bending carriage not holding the material bends the material or is moved along said material, characterised in that, in order to immovably hold the material (18, 142, 160), an unbent section, interacting with a bending carriage (14, 16, 144, 146, 156, 158), is bent to an angle α which results exclusively in elastic deformation.
2. Method according to claim 1, characterised in that, in each bending operation, the angle α is added to the desired angle of bend β determining the final shape of the material (18, 142, 160).
3. Method according to claim 1, characterised in that the angle α is the maximum angle to which the material is bendable, without the occurrence of plastic deformation.
4. Method according to claim 1, characterised in that, after the first bending operation has ended, in the event of further bending operations, the bend to the angle α is neutralised during the bending of the material with the other bending carriage.
5. Method according to claim 1, characterised in that, in the region of a bending carriage, bent sections of material are lifted over sections of material to be bent.

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