EP0492211A1 - Method for bending hollow metal profiles and apparatus for carrying out this process - Google Patents

Abstract

A description is given of a thrust-bending method involving a rolling mandrel, the said method being used to bend hollow metal profiles. Starting from the known roll-bending method, in which the interior of the hollow profile (11) to be bent is filled and the profile moved into a bending station comprising a plurality of bending rollers (2, 3), the movement of the bending rollers in the bending plane produces the bend in the hollow profile. In order to obtain the advantages of core stretch bending while avoiding the high costs of this method, the invention provides that the hollow profile of the workpiece be filled by a base mandrel (4) and that the workpiece (11) be pushed into the bending station under the action of thrust. The workpiece to be bent is thus pushed over the mandrel (4), which is fixed in the bending zone, by the thrust and by the frictional force of the shaping rollers and is bent in the XYZ plane by the bending station. <IMAGE>

Description

The invention relates to a method for bending hollow metal profiles according to the preamble of claim 1 and a device for carrying out the method.

So far, a so-called core stretch bending process is known, which is characterized by the following features:

There is a bending form, which is arranged rotatably driven on a tool carrier. The profile is clamped and bent around this core by applying a tensile force to the profile to be bent.

With a core stretch bending process of this type, in which mandrels are also carried in the cavity of the profile when using hollow profiles, it is possible to form complicated profiles even with narrow radii.

It is not necessary to fill and stabilize the hollow profile with sand or other support materials.

The core stretch bending process is used above all when large numbers of workpieces to be bent are required, where a synchronous bending process always takes place in succession on the same bending shape.

Core stretch bending according to the known state of the art is also used whenever what is also known per se Roll bending processes with narrow radii can no longer be used.

The roll bending process is a reshaping of a workpiece between bending rolls, which are designed as profile rolls. There can be three or four profile rollers, usually two lower bending rollers spaced apart from one another, which may be tilted or pivoted on a housing, with a fixed, upper bending roller available opposite the two lower bending rollers which engages in the distance between the two lower bending rollers. The profile to be reshaped is introduced into the space between the upper bending roller and the two lower bending rollers, which are spaced apart, and is guided through the rotary drive of the bending rollers. The shaping then takes place around the upper middle roller (bending roller).

In another embodiment, it is known to arrange the two lower bending rollers firmly on a machine tool and to design the upper, middle bending roller to be deliverable in the space between the two lower bending rollers in the direction of the workpiece.

Instead of the three-roller bending machine described here, it is also known to use a fourth, middle bending roller, the fourth, middle bending roller being arranged below the upper, middle bending roller.

This has the advantage that the profile cannot deflect downward relative to the upper, middle bending roller because it is guided and supported by the lower, middle bending roller.

The decisive factor here is not the downward-looking leadership of the profile, but also the lateral guidance, which is achieved by the lower, middle bending roller.

This roll bending process with three or four bending rollers is used whenever you have to bend larger bending radii depending on the profile size or small quantities, which can also have different radii.

When bending hollow profiles with such three or four-roll bending machines, it is generally necessary for the hollow cross section to be filled in order to support and stabilize the hollow cross section. This measure of filling the hollow profile for the purpose of support during the bending process takes time and is relatively expensive. By filling the hollow cross-section with a filling material, the bending resistance increases, and thus also the specific surface pressure on the profile, which is now necessary to bend the stiffened profile. This causes evasive phenomena and rolling on the hollow profile, which in turn are undesirable and have negative effects on the quality of the bending process.

The present invention has for its object to develop a method of the type mentioned with respect to a three- or four-roll bending machine so that you can inexpensively produce even tight radii of a hollow profile without using the relatively expensive core stretch bending process for tools.

To achieve the object, the method according to the invention is characterized by the features of claim 1. It is therefore important that the profile to be bent is bent in a known three, four or multiple bending roller station, that the profile is filled with a mandrel and that the bending zone stiffened by the mandrel Hollow profile and the resulting increased bending resistance is compensated for by the fact that the profile to be bent is subjected to a shear force on the feed side to the bending roller station.

The technical teaching according to the present invention is that you no longer have to pour or fill the hollow profile to be bent with a material, but that you use a relatively inexpensive mandrel, which is designed either as a solid mandrel or as a sectional mandrel.

It was recognized that such a mandrel made the forming process very difficult and - without further countermeasures - impaired the quality of the forming.

In order to compensate for these negative phenomena, the invention provides that the profile is inserted between the rollers of the bending roller station from the feed side of the profile with a pushing force. In this way, the bending process is made much easier and the quality is improved.

The mandrel remains at the bending point while the profile is pushed over the fixed mandrel with a pushing force. Compression forces now occur between the fixed mandrel, the hollow profile pushed over the mandrel and the associated bending rollers at the bending point. The thrust on the hollow profile only makes such a transformation possible. If such a thrust were missing, then the frictional connection between the rotating driven bending rollers and the outer circumference of the hollow profile would no longer be sufficient to guide the hollow profile through the forming zone at a constant speed, due to the high induced resistance by the mandrel filling the hollow profile.

If, according to the invention, a pushing force is now exerted on the hollow profile, then there is no longer a need for a high frictional engagement and a corresponding torque between the bending rollers and the outer circumference of the hollow profile, because the hollow profile is pushed through the bending rollers.

It is important here that a combination of the frictional forces of the bending rollers and the thrusting forces is applied to the hollow profile in order to optimize the forming performance of the bending rollers.

On the other hand, it is possible not to drive the rollers in rotation, but to let them run idle and to carry out the forming process by means of the thrust force applied to the workpiece from the feed side.

In a further embodiment of the present invention, it is provided that, instead of the bending rollers described above, fixed sliding jaws are used, which are seated on the outer circumference of the hollow profile with corresponding friction-reducing coverings. In this embodiment, too, it is characteristic that the hollow profile is filled with a fixed or with a link mandrel at least in the bending zone and that the hollow profile is then pushed through the sliding jaw arrangement with the necessary thrust required for the bending process.

In all the embodiments described, it is important that the thrust force applied to the workpiece on the feed side does not lead to bulging of the hollow profile on the feed side. For this purpose, it is provided that the profile is guided on the feed side in front of the bending roller station or the sliding jaw station with a profile roller guide station. This profile roller guide station thus serves to avoid buckling of the profile being fed in Bending roll or slide jaw station.

Instead of a profile roller guide station, several stations can also be used.

The thrust to be applied to the hollow profile is generated by a profile thrust carriage which consists of a roller vehicle or sliding vehicle which is driven to be movable in a U-shaped or similarly profiled rail bed. This profile sliding carriage here has a push arm in the form of a crossmember, which exerts a pushing force on a cover attached to the front of the workpiece, so that this rod-shaped workpiece is pushed through the bending station, the rotationally driven bending rollers of the bending station supporting the push.

In another embodiment of the present invention, it is provided to use a collet instead of an end cover and on a push arm of the profiled push slide which is connected to a slide driven in the axial direction of the workpiece. The collet then grips the hollow profile on its outer circumference and the slide driven in the axial direction of the workpiece then pushes this clamped workpiece into the profile roller station.

In a preferred embodiment of the present invention, the bending roller station is also further developed in a special way. Protection for these further features is also claimed within the scope of the present invention.

The bending roller station according to the present invention does not consist of a conventionally known three or four bending roller arrangement, but from an at least six-roller bending arrangement.

It is essential that the profile to be bent is first guided exactly straight between at least four bending rollers (two pairs of bending rollers) in order to prevent it from evading upwards or downwards.

At the outlet of this four-roller bending arrangement there is a cross slide which can be displaced in at least two mutually perpendicular directions and which carries a further pair of bending rollers.

The profile to be bent is thus bent in the space between the four-roller arrangement and the bending rollers on the cross slide. The main advantage here is that the profile to be bent can be bent in both directions (in the drawing to be explained later Figure 1: vertically up or down) or to the left or right.

All six bending rollers are driven in rotation and it is essential that there may be more bending rollers; In the exemplary embodiment to be explained later, there are still smaller rollers which still clamp and guide the profile in the space between the larger bending rollers, or one or more of the larger bending rollers can also be replaced by smaller bending rollers instead of the four larger bending rollers.

With the described bending device, there is the essential advantage that one can bend with respect to a horizontal plane (XY) to the left and right in any radius, the radii depending on the displacement of the cross slide and the bending rollers arranged thereon and the thrust exerted.

The advantages of the invention result in particular when bending large-volume profiles. Such large-volume profiles were previously bent using the core stretching process, which was associated with the disadvantage that one only had a fixed bending shape and could bend a relatively small radius with this fixed bending shape. Larger bending molds could not be produced for economic reasons, because then bending molds with a radius of 20 m and more would be required, for example, which can no longer be produced with reasonable effort.

To bend this profile, it was also necessary that the cavity be filled with a material, which is particularly expensive for large-volume profiles.

This is where the advantages of the present invention come in, because a bending shape that is fixed in the radius is avoided and instead any bending radii can be bent with high precision, with the advantages of core stretch bending, namely that a precise cross-sectional stabilization of the profile shape during the forming process by means of a mandrel takes place and at the same time the high variability of the radius guidance is achieved, which could only be achieved with the conventional three- or four-roller bending process.

This means that even long profiles according to the present invention with lengths of, for example, 20-30 m with bending radii of small radii starting from, for example, 1 m can be infinitely bent up to a bending radius. This combines the advantages of core stretch bending (high precision, narrow radii) with the advantages of roll bending forming, namely bending any radius, regardless of a bending shape, of any length.

In a further development of the present invention, it is provided that not only does the profile bend in one plane (XY plane), but also that a torsion is applied in that the compound slide is arranged so as to be pivotable in the direction of the longitudinal axis of the workpiece, around the to twist the profile to be bent, if this is necessary.

In a further embodiment of the present invention, it is additionally provided that the cross slide that can be moved in the XY direction can also be moved in the Z direction, so that a spatial bending of the profile in the XY-Z plane is possible.

The torsion bend, which can extend in all three spatial axes, is then added as a further level.

The cross slide must then sit on another slide which can be moved in the Z direction. The entire shift in the XY and Z planes can be CNC-controlled or PLC-controlled or can be realized in the interaction of both control systems.

The subject matter of the present invention results not only from the subject matter of the individual patent claims, but also from the combination of the individual patent claims with one another. All information and features disclosed in the documents - including the summary -, in particular the spatial design shown in the drawings, are claimed to be essential to the invention insofar as they are new to the prior art, individually or in combination.

The invention is explained in more detail below with the aid of drawings which illustrate only one embodiment. Here go from the drawings and their description further essential to the invention

Features and advantages of the invention.

Figur 1:

schematisiert in Draufsicht eine Vorrichtung zur Ausübung des RDSB-Verfahrens,

Figur 2:

der Schnitt durch einen Profil-Schubschlitten,

Figur 3:

Schnitt gemäß der Linie III-III in Figur 2 durch den Profil-Schubschlitten mit Werkstück,

Figur 4:

die Seitenansicht einer Dornhaltestation mit teilweisem Schnitt.

Show it:

Figure 1:

schematized in plan view a device for exercising the RDSB method,

Figure 2:

the cut through a profile sliding carriage,

Figure 3:

Section along the line III-III in Figure 2 through the profile sliding carriage with workpiece,

Figure 4:

the side view of a mandrel holding station with a partial section.

The device for practicing the RDSB method (roll-mandrel-push-bend method) essentially consists of a machine table 10 on which the rod-shaped workpiece to be bent is arranged displaceably in the direction of its longitudinal axis. In the interior of the workpiece 11 designed as a hollow profile, a base mandrel 4 is arranged, which in the exemplary embodiment shown is formed in two parts and consists of a rear, fixed mandrel body 12 and a front, articulated, flexible link mandrel 13. The two parts are connected.

At the rear end of the mandrel body 12 there is a mandrel holding rod 15 (see also FIG. 4), which is received in a mandrel holding station 7.

A profile sliding carriage 6 also acts on the workpiece 11 (see FIGS. 2 and 3) and pushes the workpiece 11 into the bending station 5 in the direction of the arrow 16.

The bending station has a total of 8 bending rollers, the interaction of which is described below.

There are two bending roller pairs 2, 3, which are rotatably arranged on the machine table 10 and are each driven in the arrow directions shown.

The lower bending rollers of the pair of bending rollers 2, 3 can be slidably mounted on a separate slide in the arrow directions 17 on the machine table 10 in order to make the gap between the bending rollers 2 and 3 adjustable in order to adapt this gap to the workpiece width.

In addition, a further, smaller pair of bending rollers 18 can be arranged in the space between the two larger bending roller pairs 2, 3.

A further pair of bending rollers 21, which is arranged on a cross slide 1, is arranged behind the bending roller pairs 2, 3 in the transport direction of the workpiece. It can be provided here that the lower roller of the pair of bending rollers 21 can also be advanced to the upper roller in the direction of arrow 17, as was illustrated with the aid of the bending roller arrangement 2, 3.

The cross slide 1 can be moved in two mutually perpendicular arrow directions 19, 20 (X-Y direction), so that the workpiece 11 received between the bending roller pair 21 can be freely bent in the X-Y plane.

In addition, it is provided that the cross slide 1 is arranged to be rotatable about the longitudinal axis of the workpiece 11 in order to give the workpiece torsion (if desired (in addition to the bend in the XY direction) give.

In a third embodiment, not shown in the drawing, it can be provided that the cross slide 1 is part of a further slide, so that the cross slide 1 can also be moved perpendicular to the plane of the drawing in FIG. 1 (in the Z direction), so that the workpiece is three-dimensional can be bent and additionally twisted.

It is important that the mandrel body 12 of the base mandrel 4 is arranged in the bending zone 14, a link mandrel 13 possibly also being able to connect to the mandrel body 12.

The bend can thus take place in all levels, such as. B. in the XY plane, the XZ plane, the YZ plane or the XYZ plane. As explained at the beginning, the bending of the workpiece 11 with a base mandrel 4 arranged therein is extremely difficult due to the base mandrel 4 engaging in the hollow profile. In order to eliminate such bending resistances, it is now provided that the profile of the workpiece 11 in the arrow direction 16 into the bending station 5 of a profile slide carriage 6 is inserted. The structure of the profile carriage 6 will be explained later with reference to Figures 2 and 3.

So that the workpiece 11 does not buckle laterally in the area of the thrust on the machine table 10, a profile roller guide station 8 is provided which receives the profile between them and guides it in a form-fitting manner.

The profile roller guide station is displaceable and fixable on the machine table 10 along the workpiece and has guide rollers 42 which form-fit against the outer circumference of the workpiece 11.

Instead of a single profile roller guide station 8, several can be arranged in succession at a mutual distance.

In order to guide the profile roller guide station and the profile slide carriage 6, a guide track 9 is arranged on the machine table 10, in the area of which the parts 6, 7, 8 are guided so that they can be moved and locked.

The base mandrel 4 is held here by a mandrel holding rod 15 which is firmly received in a mandrel holding station 7.

FIG. 2 shows the sectional view through a profile sliding carriage 6.

It can be seen that a guide carriage 22 is slidably guided in the interior of a hollow profile 25 via four rollers 24. The guide carriage 22 is connected here via a cross member 26 to a spindle nut 27 which engages around a drive spindle 28.

The drive spindle 28 is rotatably driven in the arrow directions 29 shown.

The cross member 26 extends through an upper, horizontally running slot 30 of the hollow profile 25 and is firmly connected to a plate 31.

The plate 31 has an inner shoulder 32 which engages in the hollow profile of the workpiece 11.

The plate 31 and the neck 32 are adapted to the inner profile of the workpiece 11, so that the neck 32 on the one hand positively to the The inner circumference of the workpiece 11 is applied and on the other hand the plate 31 is applied to the rear end face of the workpiece 11.

The two parts 31, 32 have a bore 33 through which the mandrel holding rod 15 engages with sufficient radial play. If the drive spindle 28 is now driven in one of the arrow directions 29 shown, then the spindle nut 27 screws on the drive spindle, so that the entire guide carriage 22 is moved in the arrow direction 16 along the machine table 10. Thus, the rear face of the workpiece 11 is pushed in the direction of arrow 16 along the machine table into the bending station 5 via the cross member 26 and the parts 31, 32. Here, the mandrel holding rod 15 remains stationary with respect to the machine table 10.

As a result, the required thrust in the direction of arrow 16 is generated on the workpiece 11 in the direction of the bending zone 14. After the mandrel holding rod 15 stops with the base mandrel 4, the workpiece 11 is thus pushed over the fixed mandrel in the direction of arrow 16 and at the same time is offered by the bending station 5 in connection with the movable bending station (cross slide 1).

Figures 2 and 3 show, moreover, that on the underside of the workpiece a friction pad 36 can still engage, which frictionally engages the workpiece 11 and is connected to the guide carriage 22.

FIG. 3 also shows (in addition to FIG. 2) that guide rollers 34, 35, which are connected to the guide carriage 22, can still be placed on the outer circumference of the workpiece 11.

Incidentally, it is pointed out that the profile roller guide station 8 is constructed in exactly the same way as this is done with the guide carriage 22 in FIG 3 was explained, only that the part 31, 32 exerting the thrust on the workpiece in connection with the cross member 26 is missing in the profile roller guide station.

Otherwise, the profile roller guide station 8 uses the same arrangement as explained in FIGS. 2 and 3, it being particularly important that the guide rollers or sliding jaws 34, 35 shown in FIG. 3 are present in this profile roller guide station in order to maintain the profile of the workpiece 11 under thrust to prevent it from buckling.

Instead of the guide rollers shown in Figure 3, sliding jaws can accordingly be used.

In another embodiment, not shown in the drawing, it is provided that instead of the thrust shown in FIG. 2 on the rear end face of the workpiece 11 via the parts 31, 32, a collet chuck can also be used, which engages positively and positively on the outer circumference of the workpiece and possibly also engages in the inner circumference of the workpiece in order to clamp the workpiece without deformation and to drive it so that it can be displaced in the direction of arrow 16.

Figure 4 shows schematically the section through a mandrel holding station. It is important here that the mandrel holding station is also designed to be displaceable in the direction of arrow 16 and in the opposite direction.

According to the bending task, the base mandrel 4 must always be held in the bending zone 14. However, the bending zone 14 is not a constant point between the front pair of bending rollers 2 of the bending station 5, but the bending zone 14 can change in the axial direction along the workpiece 11. In order to take these changes into account, the base mandrel 4 must be adjusted in the direction of the arrow 16 or 16 ' will. Here, a guide carriage 37 is also arranged in the region of the hollow profile of the guide track 9, which is supported with assigned rollers 24 on the inner circumference of the hollow profile of the guide track 9. The guide carriage is connected to a cross member 38 which extends through a slot 30 in the top of the guide track 9 and is connected there to a clamping head 39. The clamping head has a front lathe chuck 40, which receives the mandrel holding rod 15 on the rear face.

The locking device 41 between the guide carriage 37 and the associated guideway 8 is only shown schematically. In the normal case, the base mandrel 4 is thus pushed into the workpiece 11 and advanced into the bending zone 14. The locking device 41 is then switched on so that the guide carriage 37 remains firmly anchored in the hollow profile of the guideway 9.

A possibly necessary tracking of the mandrel into the changing bending zone 14 is accomplished by the lathe chuck 40, which is rotatably arranged in the clamping head 39 and can also be displaced and locked in the axial direction of the workpiece (in the arrow directions 16, 16 '). The control of the lathe chuck 40 in the arrow directions 16, 16 'or in the direction of rotation around the mandrel holding rod can be carried out hydraulically, mechanically or electromechanically.

Instead of the guide carriages 22, 37 described here, a guide rail system with slide can also be used, which is also precise in the guide. It is only important that a push is exerted on the workpiece in the direction of arrow 16 by the profile sliding carriage 6 and that the profile roller station 8 is also arranged displaceably and ascertainably in the guideway 9 and, moreover, the mandrel holding station 7 is likewise displaceably and identifiable in the guideway 9 and the rest of the mandrel support rod 15 locked mandrel holding station 7 in the arrow directions 16,16 'is adjustable.

The particular advantage of the method according to the invention is that no more fillings of the hollow profile of the workpiece 11 are required because the required profile stabilization is carried out by the base mandrel 4. A profile filling with sand or pouring with other materials can be omitted. Radii can thus be infinitely bent in the workpiece 11, it being possible to bend different radii in succession. Due to the CNC control of the entire machine, bending processes can be carried out automatically with great repetition accuracy.

This makes it possible for the first time to achieve mutual bending in the form of a sinus line in addition to normal roll bending (with a three- or four-roll bending machine). The bending direction can thus be changed continuously in the positive or negative direction, which corresponds to a snake shape to the left or right in the XY plane.

If the cross slide 1 is also designed to be movable in the Z direction, it is also possible to bend in the third bending plane and, in addition, a torsional movement can be superimposed on all the bending movements.

Claims (12)

Method for bending metal hollow profiles according to the roll bending method, in which the hollow profile to be bent is filled in its interior and is inserted into a bending station consisting of several bending rollers, the bending of the hollow profile taking place by moving the bending rollers in the bending plane, characterized in that that the hollow profile of the workpiece (11) is filled by a base mandrel (4) and that the workpiece (11) is inserted into the bending station (5) under the action of thrust. A method according to claim 1, characterized in that the thrust force is applied to the workpiece (11) in the direction of its longitudinal axis. Method according to claim 1 or 2, characterized in that a rotational movement is superimposed on the thrust force on the workpiece (11). Method according to one of claims 1-3, characterized in that the base mandrel (4) is arranged displaceably and lockably in the bending zone (14). Device for carrying out the method according to one of Claims 1 -4, characterized in that a base mandrel (4) fastened to a mandrel holding rod is arranged in the hollow profile of the workpiece (11) and in that on the feed side of the workpiece (11) in the bending station (5 ) a thrust device is arranged, which exerts a longitudinal thrust on the workpiece (11). Apparatus according to claim 5, characterized in that the pushing device consists of a profile pushing carriage (6) which is displaceably driven along a guideway (9) and which is positively or non-positively or loosely connected to the workpiece (11). Apparatus according to claim 5 or 6, characterized in that, in order to prevent the workpiece (11) from being pressed out, one or more profile roller guide stations (8) on the feed side to the bending station are arranged displaceably and ascertainably along the guide track (9) which the workpiece ( 11) at least partially grip the outer circumference. Device according to one of claims 5-7, characterized in that the bending roller station (5) consists of a number of bending roller pairs (3, 4, 18) forming a fixed passage gap and furthermore at least one in the bending plane (X, Y, Z) displaceable and possibly rotatable bending roller pair (21). Device according to one of claims 5-8, characterized in that the base mandrel (4) consists of a bendable mandrel body (12) filling the hollow profile of the workpiece (11). Device according to one of claims 5-8, characterized in that the base mandrel (4) is designed as a link mandrel (13). Device according to one of claims 9 or 10, characterized in that the base mandrel (4) on a mandrel holding rod (15) is fastened, which is fastened in a mandrel holding station (7), which mandrel holding station (7) is arranged displaceably and fixably along the guide track (9). Apparatus according to claim 11, characterized in that the mandrel holding rod (15) is rotatably received in a lathe chuck (40) of the mandrel holding station (7).

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