Arrangement For Bending Of Bars Of Reinforcing Steel Mats

Abstract

Arrangement for bending of reinforcing steel mats with a fixed support beam having a bearing surface for receiving and supporting a reinforcing steel mat. A plurality of spaced hook-like bending mandrels are coaxially operatively mounted over the bearing surface. A pivoting bar engaging beam, having a pivot axis disposed parallel to the bearing surface, is provided with a plurality hook-like bar bending members each of which coacts with a hook-like bending mandrel. The supporting beam being further provided with a multipart bending shoulder and the pivoting bar engaging beam being swingably at least on one side of the bearing surface behind the multipart bending shoulder.

Description

BACKGROUND OF THE INVENTION

The invention relates to an arrangement for bending reinforcing steel mats. This arrangement comprises a fixed support beam having a bearing surface for receiving the reinforcing steel mats, and a plurality of bending mandrels coaxially arranged above the bearing surface. These plurality of bending mandrels are spaced from each other and have hook-like shapes. A pivoting bar engaging beam is swingably mounted about an axis which is parallel to the bearing surface and a plurality of bar engaging members are adapted to coact with the bending mandrels.

There are already known arrangements for bending reinforcing steel mats. In these known arrangements, the reinforcing steel mat is disposed between the swinging axis of a pivoting member and the bending mandrel. The bar engaging members are more or less moveable in a cap-like manner over the bending mandrel in this known arrangement (see for example, German Pat. No. 1,234,177). The reinforcing steel mats may be bent about an arch up to 180.degree. with this arrangement. However, the bending may only be carried out at one side of the support and thus only at one side of the reinforcing steel mat and the surface supporting it. There are also known bending machines wherein a bending beam is lifted over the reinforcing steel mat and the supporting surface and carries out a bending of the mat downwardly, that is below the supporting surface. This known arrangement has the drawback that the finished bent reinforcing steel mat can only be removed from the arrangement after the bending beam of the supporting member has been moved from the arrangement.

If the reinforcing steel mat is to be bent at different locations and in different bending directions at these different locations with the known bending machines, the reinforcing mat must be frequently moved between the individual bending steps, that is it must be frequently turned, which requires a long time and a large energy input. Furthermore, the necessity of having to turn the reinforcing steel mat makes it practically impossible to carry out the bending steps completely automatically. In order to make this bending operation at least partially automatic, it is necessary to construct a complex installation which is a further drawback in the known arrangements. There has been proposed a bending arrangement (see for example German Utility Model No. 1975 712) in which there is arranged a pivoting beam at both longitudinal sides of the support beam. This arrangement does somewhat facilitate the fabrication of certain types of reinforcing steel mat profiles. The versatility of this arrangement is however limited since it can only bend the reinforcing steel mat in one direction, that is upwardly from the supporting surface.

SUMMARY OF THE INVENTION

It is accordingly a primary object of the present invention to provide an installation for bending reinforced steel mats, which can bend in both direction with respect to the supporting or bearing surface of the steel mat without requiring the mat to be locked in the installation.

It is another object of the invention to dispense with the necessity of having to turn the reinforcing steel mat in the installation even when difficult cross sectional profiles having a plurality of bent locations are required to be fabricated by means of the installation.

The installation of the invention has a pivoting beam having a plurality of rod engaging hook-like members which coact with hook-like bending mandrels disposed on the supporting beam. The reinforcing steel mat is located in a transfer space and the pivoting beam is mounted in the installation in such a way that it can be pivoted at least on one side behind a uni- or multipart shoulder of the installation. In this manner, a reinforcing steel mat can be bent at one side of the supporting or bearing surface of the support beam of the installation about bending mandrels in an angular range of 0.degree.-180.degree. as well as on the other side of the bearing surface about a bending shoulder in an angular range of 0.degree.-135.degree.. By shaping the rod engaging members like hooks, the reinforcing steel mats can be easily removed after the bending of the individual bars has been completed without the necessity of removing any members of the installation before removing the reinforcing steel mats.

It is also contemplated by the present invention to provide an installation wherein a pivoting beam is provided at both sides of the supporting beam, each pivoting beam operating in the afore-described manner. The pivoting beams are supported at several locations along their length. With such an arrangement it is possible to carry out bending of the reinforcing steel mats at both sides of the supporting beam upwardly as well as downwardly with respect to the bearing surface. Thus with such an installation it is possible to fabricate reinforcing steel mats with complex profiles which have a plurality of differently directed bending points, the fabrication being carried out without the necessity of removing the steel mat from the installation.

It is also contemplated by the present invention to provide an installation with a single pivoting beam which is arranged underneath the supporting beam and can be pivoted selectively from one to the other side of the supporting beam. The rod engaging mandrels are disposed on the pivoting beam in such a manner that these rod engaging mandrels can be selectively moved to either side of the bearing surface during the bending process. Two rows of coaxially arranged rod engaging mandrels are mounted on the pivoting beam, these two rows being arranged symmetrically with respect to a plane extending through the pivot axis of the pivoting beam, said pivoting axis of the pivoting beam extending in a symmetrical plane of the fixed supporting beam.

The supporting beam is advantageously provided along both sides of the bearing surface on which the reinforcing steel mat rests with longitudinal shoulders which assist in the bending process. The bending mandrel which serves to assist in the bending of the reinforcing mats to the other side of the bearing surface can be disposed in the same symmetrical plane as the axis of the pivoting beam. Thus in this embodiment of the present invention, the pivoting beam can be pivoted from one to the other side of the supporting beam. The two rows of rod engaging mandrels can via the supporting beam affect bending of the reinforcing mat on both sides of the supporting beam upwardly as well as below the bearing surface supporting the steel mat.

The rod engaging mandrels as well as the bending mandrels can be provided with rollers which facilitate the bending process. Furthermore, the supporting beam may be provided at its underside with curved portions which coact with the rollers of the rod engaging mandrels mounted on the pivoting beam. Thus, when the pivoting beam is formed symmetrically and the pivot axis is located in a symmetrical plane of the supporting beam, a portion of the rod engaging mandrels are shored-up over a predetermined bending range during a bending process at the supporting beam, whereby a lightening of the load on the supporting beam is attained.

A further substantial advantage of the arrangement in accordance with the invention is attained by mounting the bending mandrel adjustably relative to the bearing surface of the supporting beam so that it can be pressed against a reinforcing steel mat introduced into the installation by means of a common work-locating fixture. In this manner, the movement of the reinforcing steel mat, which generally occurs and is undesirable, can be prevented during all types of bending processes. The arrangement in accordance with the invention not only makes it possible to carry out an increased number of types of bending operations, but also makes it possible to fabricate reinforcing steel mats with precision.

The bending mandrels which coact with the work-locating fixture are provided at their shank portion with inclined guiding surfaces which coact with the mating guiding surfaces of a common actuating member which is slidably mounted in the supporting beam. The inclined guiding surfaces of the actuating member are formed by a lateral projection which extends into a mating inclined groove in the shank portion of the bending mandrel. The pivoting beam and the work-locating fixture can be driven and actuated by mechanical, hydraulic or pneumatic means, in a known manner, and can be either controlled manually or by means of a computer. The actuating member for the work-locating fixture can, in accordance with the invention, be provided with a hydraulic actuating cylinder and piston which is arranged in the interior of the supporting beam. The piston of this cylinder and piston arrangement is operatively connected for reciprocable movement of the actuating member.

DESCRIPTIONS OF DRAWINGS

The invention is illustrated by way of example in the accompanying drawings which form part of this application and in which:

FIG. 1. is a schematic elevational view of the entire installation for bending reinforcing steel mats in accordance with a first embodiment of the invention;

FIG. 2. is a cross-sectional view along Line II -- II of FIG.1 wherein the pivoting beam is shown in a first position;

FIG. 3. is a cross-sectional view along Line III -- III wherein the pivoting beam is shown in a second position;

FIG. 4. is a partial cross-sectional view of the supporting beam along line IV -- IV of FIG. 3;

FIG. 5. is a cross-sectional view at the same location as the cross-sectional view illustrated in FIGS.2 and 3 relative to the elevational view of FIG. 1. of a second embodiment of the installation for bending reinforcing steel mats;

FIG. 6. is a partial side elevational view of the second embodiment of the invention in the region where the pivoting beam is supported on the support beam;

FIG. 7. is a partial side elevational view of a third embodiment of the invention;

FIG. 8. is a cross-sectional view along Line VIII -- VIII of FIG. 7 in the region of the bending means of the installation; and

FIG. 9. illustrates the bending means of the third embodiment in a different position than that of FIG. 8.

DESCRIPTION OF PREFERRED EMBODIMENTS

Referring now to FIG.1 where there is illustrated a first embodiment of the installation for bending of reinforcing steel mats, there are shown two lateral column supports 10 and 11 on which there is mounted a support beam 12. The upper side of the support beam 12 has a bearing surface 13 for receiving the reinforcing steel mats. A plurality of hook-shaped bending mandrels 14 removeably mounted in the support beam 12. These bending mandrels 14 are adjustably mounted in the support beam 12 so that the distance between the bearing surface 13 and the bending mandrel 14 can be adjusted. as will be described below. The bending mandrels 14 are coaxially arranged in support beam 12 at equal distances, said distances corresponding to the standard distances employed for reinforcing steel bars in reinforcing steel mats. The hook-shape of the bending mandrels makes it possible to freely insert a reinforcing steel mat on the bearing surface 13 of the support beam 12 and introduction of the longitudinal rods of the reinforcing steel mat under the bending mandrels 14 by laterally sliding the steel mat on the bearing surface 13. As can be noted from FIGS. 2 and 3, the support beam 12 is provided at both of these longitudinal sides with bending shoulders 25 and 26 of semicircular cross-section which can coact with the rods of the reinforcing steel mats during the bending process.

The bending installation has, furthermore, a pivoting beam 15 which is swingably mounted on the support beam 12 by means of a pair of arms 16 extending from opposite ends of the pivoting beam 15 as is shown in FIG. 1. The pivoting beam 15 can advantageously be also supported at its middle by means of a standard pivot support and thus extends parallel to the support beam 12. The pivoting beam 15 can thus be swung by drive means 17, which can be of the conventional mechanical, pneumatic or hydraulic type, and which, for example, swing the pivoting beam 15 by means of a gear rack 18 which engages a gear wheel 19 fixedly secured to one of the support arms 16 as shown in FIG. 1. The swinging movement of the pivoting beam 15, can however also be carried out by means of an hydraulic pressure cylinder piston arrangement (non illustrated) which swings the pivoting beam 15 by means of a crank mechanism (not illustrated). Thus the drive means for swinging the pivoting beam 15 can be embodied in any one of the conventional drive means.

As can be noted from FIGS. 2 and 3, the support beam 12 is hollow and has a free inner space 120. Each one of the bending mandrels 14 has a shank portion 140 which extends into this hollow space 120 to a pair of confronting openings 140' and 140" (see FIG. 4). All of the shank portions 140 are symmetrically aligned along a vertical symmetrical plane 120 as shown in FIGS. 2 and 3. The pivot axis 21 for the pivoting beam 15 is also situated in the vertical symmetrical plane 20. As can be noted from the full line position and dot-dash position of FIGS. 2 & 3, the pivoting beam 15 can be swung symmetrically with respect to the supporting beam 12 from one longitudinal side to the other underneath the beam 12 and also over the reinforcing steel mat supporting bearing surface 13 on both sides thereof. The pivoting beam 15 has two rows of rod engaging mandrels 22 and 23 of hook-like shape which advantageously are provided at their free ends with rollers and which are connected to the main beam 15 by means of arms 24. The two rows of rod engaging mandrels 22 and 23 are symmetrically arranged about a mid-plane which divides the pivoting member 15 into two equal symmetrical parts. The rod engaging mandrels 22 and 23 are coaxially arranged on the pivoting beam 15 in two rows so that one rod engaging mandrel is disposed on each side of the bending mandrel 14, that is the rod engaging mandrels are spaced from each other approximately the same distance as the bending mandrels 14 as can be noted from FIG. 1.

FIG. 2 illustrates the bending operation of a reinforcing steel mat, consisting of transverse rods 28 and longitudinal rods 27, in which the longitudinal rods 27 are bent in the shape of a hook. The conventional reinforcing steel mat is placed on the bearing surface 13 of the support beam 12 in the aforedescribed manner and, is slidably displaced laterally, so that the longitudinal rods 27 are situated under the individual bending mandrels 14. Before the bending operation begins, the bending beam 15 is situated in the position indicated in full lines in FIG. 2, in which both rows of rod engaging mandrels 22 and 23 are situated below the plane of the bearing surface 13. The bending operation is effected by swinging the bending beam 15 about the pivot axis 21 in a clockwise direction until it reaches the position indicated by dot-dash lines in FIG. 2. The afore-described swinging movements of the driving beam 15 brings the leading row of rod engaging mandrels 22 in contact with the longitudinal reinforcing steel rods 27 of the reinforcing steel mat and bendsthese rods around the bending mandrels 14, which are also advantageously provided with rollers, until they reach the dot-dash line position 27' indicated in FIG.2. In FIG. 3 there is illustrated an operation for bending the rods of a reinforcing steel mat at about an angle of about 90.degree.. In order to carry out this bending operation, the rod engaging mandrel 22 is situated above the longitudinal reinforcing rod 27, that is, above the bearing surface 13 of the supporting beam 12. The bending operation is carried out by swinging the pivoting beam 15 about its axis 21 in a counter-clockwise direction from the position shown in full lines to the position shown in dot-dash lines. As can be noted, the longitudinal rods 27 of the reinforcing steel mat 27/28 are bent about the bending shoulder 25 of the support beam 12 until the longitudinal rods 27 are in the position 27".

Thus the pivoting beam 15 can carry out with its large swinging angle by means of its two rows of rod engaging mandrels 22 and 23, as well as by means of the symmetrical arrangement of the bending mandrels 14 and the bending shoulders 25 and 26 on the supporting beam 12, a bending operation of a reinforcing steel mat on both sides of a supporting beam. When the bending operation is carried out outwardly around the bending mandrels 14 the rods can actually be bent over a range of 0.degree.-180.degree.. When the bending operation is carried out below the bearing surface 13 about the shoulders 25 or 26, the bending can be carried out over a range of from about 0.degree.-110.degree.. The support beam 12 is provided at its underside with a curved surface 29 against which the rollers of the rod engaging mandrels 22 and 23 can bear, so that during one portion of the angular bending range the pivoting beam 15 is shored-up at the support beam 12 and a corresponding lightening of the load is carried out at the support arms 16 of the pivoting beam 15.

The arrangement of the invention comprises further means for firmly holding or clamping the reinforcing steel mat 27/28 on the bearing surface 13 by means of the bending mandrels 14. This means for fixing the work piece on the bearing surface 13 comprises a rail member 30 disposed in the interior space 120 of the support beam 12. This rail member 30 is slidably moveably by means of a hydraulic piston and cylinder arrangement 40 as illustrated in FIG. 4. The rail member 30 has on one side inclined cam members 31, which are uniformly spaced from each other. These cam members 31 extend into inclined grooves 141 in the shank portions 140 of the bending mandrels 14 laterally disposed in the support beam 12. The bending mandrels 14 can thus be selectively moved by a longitudinal movement of the rail member 30 towards or away from the bearing surface 13 of the support beam 12, that is all bending mandrels can be jointly moved in one direction or the other. In this manner, the longitudinal rods 27 of the reinforcing steel mat 27/28 can be firmly clamped on the bearing surface 13, as is shown in FIGS. 2 and 3 by means of the dot-dash lines 14' illustrating the clamping position of the bending mandrels.

There is illustrated in FIG. 5 a cross-sectional view of a second embodiment of the invention which operates in a similar manner than the embodiment illustrated in the cross-sectional views of FIGS. 2 and 3. In this second embodiment the pivoting beam 35 is not mounted symmetrically with respect to a plane traversing the support beam 32, but is mounted about a swing axis 36 situated outside of the support beam 32 and underneath the reinforcing steel mat supporting surface 37. The pivoting beam 35 can be swung downwardly into the dot-dash line position 35', in which it is situated behind a bending shoulder 38 which projects laterally to a considerable extent from the support beam 32 thereby enlarging the reinforcing steel mat-support surface 37. The rod engaging mandrels 33 as well as the bending mandrels 34 are also hook-shaped in this embodiment. Furthermore, the rod engaging mandrels 33 are spaced a greater distance laterally from the pivoting beam 35, so that when the pivoting beam assumes the position 35' indicated in dot-dash lines in there is provided a space through which the longitudinal rods 27' which have been bent around the shoulder 38, can be moved. This feature makes it possible to remove the bent reinforcing steel mat from the installation by a lateral movement away from the bending mandrel 34 and the rod engaging mandrel 33 without requiring the disassembling of any parts of the installation.

The pivoting beam 35 is also illustrated in a third position 35" in FIG. 5, in which it effects a bending of a longitudinal rod 27 into outwardly directed hooks 27" illustrated in dot-dash lines in FIG. 5.

The embodiment of FIG. 5 has the advantage of making it possible to support the pivoting beam 35 at a plurality of locations along its length. This feature is illustrated in FIG. 6 where the bending shoulder 38 is provided with cutouts extending up to the bending axis 38 in which there is mounted a support arm 39 of the pivoting beam 35. The holding arm 39 is pivotally mounted in the region of the bending shoulder 38 by means of a pivot pin 39' and a bearing support 39" which is rigidly secured to the support beam 32 in a conventional FIG. 5 manner which has not been illustrated in detail. The embodiment of FIGS. 5 and 6 has the drawback that the bending of the reinforcing rods can only be carried out outwardly and downwardly relative to the support beams 32 on one side thereof. This drawback can be removed by simply redesigning the support beam 32 so that it is symmetrical about a mid-plane, that is that it has a second non-illustrated shoulder 38 extending from the other sidethereof on which there is pivotally mounted a second pivoting beam 35 (not illustrated) having a corresponding number of non-illustrated rod engaging mandrels 33. Both pivoting beams would be separately driven by separate driving means which could also be computer-controlled. The rod engaging mandrels 33 and the bending mandrels 34 are correspondingly spaced and arranged relative to the longitudinal rods 27 of the reinforcing steel mat so that even with this expanded installation a bending operation of a reinforcing steel mat can be carried out in both sides of the support beam upwardly as well as downwardly relative to a bearing surface, and after each bending operation the reinforcing steel mat can be freely removed from the installation.

Thus even in this additional variation of the embodiment illustrated in FIGS. 5 and 6, the bending mandrels 34 can be connected with a clamping and work-fixing means as was described in connection with FIG. 4. In an arrangement where each side is provided with a pivoting beam 35 and thus requires two rows of bending mandrels, the bending mandrels of both rows can be actuated by means of a single rail member, which, for example, is provided at both of its level sides with inclined cams and thus can effect a simultaneous clamping action on two rows of bending mandrels.

The arrangement of the invention can be so modified that all types of radii of curvature can be effected with the machine of the invention. For example, the bending mandrels 14, 34 and the pivoting beam 15, 35 with its rod engaging mandrels 22,23 can be exchanged or adjusted, as is for example described in German Pat. No. 1,283,790 of the same inventor and assignee. For example, the pivoting beams can be embodied as two coaxially arranged pipes wherein the inner pipe is provided with supporting arms on which the beam is mounted and in which the outer pipe is rotatable and supports the rod engaging mandrels. The bending mandrels of the support beams can be removeably mounted and can be exchanged with bending mandrels of different diameters. It is furthermore contemplated by this invention to provide bending mandrels which have exchangeable, eccentric insertable pieces of different diameters, FIGS. 7 to 9 illustrate such an embodiment for bending reinforcing steel mats in which the pivoting beam is mounted on two concentric pipes. Thus it can be noted that there is provided an outer pipe 151 and an inner pipe 152. A similar arrangement is disclosed in German Pat. No. 1,283,790. The outer pipe 151 has slit-like openings, not clearly visible in FIGS. 7 to 9, in to which there extend supporting arms 43 on which is mounted a pipe 40 acting as a support beam. This pipe 40 extends to a support ring 44 which is rigidly secured to the arm 43 or is integral therewith. The support arms 43 perform a function similar to the function performed by the support arms 16 of the embodiment of FIG. 1 and, therefore, only one support arm has been illustrated. In a manner similar to the other described embodiments there is provided a non-illustrated hydraulic drive means which is operatively connected either to the arms 43 or the support ring 44 for pivoting the pivoting beam 151/152 about the longitudinal axis of the pipe 40 acting as a support beam during the bending operation.

The pipe 40 acting as a support beam is, as in the other embodiments, provided with bending mandrels 45 onto which there can be mounted bending cylinders 46, 46' of different diameters. In lieu of the bending shoulders 25 and 26, which are incorporated in the embodiment of FIGS. 1 to 3, there are provided a plurality of lateral bending mandrels 47 and 48 which are securely mounted on the pipe 40. These bending mandrels 47 and 48 can also be changed by mounting thereon bending cylinders 49 and 50 of different diameters.

The arrangement can be adjusted for different diameter bending mandrels, such as for example an adjustment from a bending cylinder 46 of a small diameter to a bending cylinder 46' of a much larger diameter, as shown in FIG. 8, by turning the pipes 151 and 152 relative to each other so that the rod engaging mandrel 41 assumes the position of the rod engaging mandrel 41' illustrated in dashed lines as shown in FIG. 8. When the pipes 151 and 152 have been so adjusted, the longitudinal rods 27" can be bent about a much larger radius of curvature as shown in FIG. 8.

The means for turning the outer pipe 151 relative to the inner pipe 152 is not illustrated in detail in the drawing because such means are conventional and well known in the arts. Such means are, for example, illustrated and described in German Pat. No. 1,283,790, wherein the aforementioned means can operate even during the bending process. Once the pipes 151 and 152 have been adjusted relative to each other, they can be secured in place by means of a conventional threaded bolt connection 152'.

FIG. 9 illustrates a bending process about a lateral bending mandrel 48. The longitudinal rod 27 of a reinforcing steel mat is bent about a lateral bending mandrel 48 on which there is mounted a bending cylinder 50 of relatively small diameter until the free end of the longitudinal rod assumes the position 27'. This bending operation is carried out by means of the rod engaging mandrel 41 shown in full lines in FIG. 9. If the rods of the reinforcing steel mat are to be bent with a larger bending radius, then the bending cylinder 50' of larger diameter is mounted on the bending mandrel 48, the bending cylinder 50' being shown in dashed lines in FIG. 9. The other pipe 151 is then turned relative to the inner pipe 152 in order to adapt the arrangement to the bending cylinder 50' until the rod engaging mandrels assume the position 41' illustrated in dashed lines in FIG. 9. In this latter position, the longitudinal rods 27 can be bent about the bending cylinder 50' until they reach the position 27".

Although the invention is illustrated and described with reference to a plurality of preferred embodiments thereof, it is to be understood that it is in no way limited to the disclosure of such preferred embodiments but is capable of numerous modifications within the scope of the appended claims.

Claims

What is claimed is:

1. An arrangement for bending reinforcing steel mats, comprising in combination:

a fixed support beam having a bearing surface for supporting a reinforcing steel mat and having at least one lateral bending shoulder;

a plurality of coaxial hook-like bending mandrels operatively mounted in said support beam over said bearing surface so that a reinforcing steel mat can be inserted therebetween;

a pivoting beam rotatably mounted in said arrangement relative to said support beam about an axis which is parallel with respect to said bearing surface;

a plurality of rod engaging mandrels mounted on said pivoting beam so that at least one rod engaging mandrel confronts each bending mandrel;

said pivoting beam being pivotable relative to said support beam over an angular range enabling the pivoting beam to move at least on one side of said bearing surface behind said lateral bending shoulder.

2. The arrangement as set forth in claim 1, wherein said support beam has a pair of lateral bending shoulders projecting from opposite sides thereof, and there are provided a pair of pivoting beams for coaction with said pair of bending shoulders.

3. The arrangement as set forth in claim 1, wherein the pivoting beam is supported at a plurality of sites extending over the length thereof.

4. The arrangement as set forth in claim 1, wherein the pivoting beam is rotatably mounted on said support beam underneath thereof so that it can be selectively moved from one side to the other of the support beam, said rod engaging mandrels being adapted to selectively carry out bending operations on both sides of the support beam from one or the other side thereof on the reinforcing steel mat in cooperation with the bearing surface of the support beam.

5. The arrangement as set forth in claim 4, wherein said rod engaging mandrels are coaxially arranged in two rows on said pivoting beam, said rows being symmetrically arranged relative to a plane passing through the pivot axis of said pivoting beam.

6. The arrangement as set forth in claim 5, wherein the pivot axis of the pivoting beam is situated in a symmetrical plane of the support beam.

7. The arrangement according to claim 6, wherein the said support beam has bending shoulders extending along opposite sides of said bearing surface, for bending the rods of a reinforcing steel mat, and said bending mandrels serving for bending said rods to the other side of said bearing surface, said bending mandrels being arranged in the same symmetrical plane wherein the pivot axis for the pivoting beam is also arranged.

8. The arrangement according to claim 7, wherein said support beam is provided at its underside with a curved surface adapted to coact with the rod engaging mandrels of said pivoting beam.

9. The arrangement according to claim 8, wherein said bending mandrels are adjustable mounted in said support beam relative to the support surface thereof, and actuating means operatively mounted in said support beam for jointly adjusting said bending mandrels so as to have the latter press against a reinforcing steel mat introduced into said arrangement.

10. The arrangement according to claim 9, wherein said bending mandrels are provided with shank portions, each one of said shank portions having a guide surface inclined relative to said bearing surface of said support beam, actuating means also having similarly inclined surfaces adapted to coact with said guide surfaces.

11. The arrangement according to claim 10, wherein said shank portions have recesses in which said inclined guide surfaces are located, and wherein said actuating means have projections on which said similarly inclined surfaces are situated, said actuating means including a longitudinal member slidably moveable within said support beam.

12. The arrangement according to claim 11, including drive means operatively connected to said longitudinal member for slidably moving it in said support beam.

13. The arrangement according to claim 12, wherein said drive means comprises a cylinder and an hydraulically actuated piston reciprocally mounted in said cylinder, said piston being connected to said longitudinal member and said cylinder being arranged inside said support beam.

14. The arrangement according to claim 10, wherein said drive means are controlled by a computer.

15. The arrangement according to claim 14, including bending cylinders adapted to be selectively mounted on said bending mandrels for changing the outer diameter thereof, and including means for adjusting the distance of said rod engaging mandrels relative to the pivot axis of said pivoting beam.

16. The arrangement according to claim 15, wherein said pivoting beam is embodied in two coaxially arranged pipes rotatable relative to each other, one of said pipes supporting said rod engaging mandrels and the other one of said pipes being rotatably mounted on the stationary portion of the arrangement.