Method and device for straightening a workpiece

Abstract

The invention relates to method for straightening a workpiece (1) with a longitudinal axis, wherein the workpiece (1) is bent out of a starting position transversely to the longitudinal axis and bent back again. In order to provide advantageous straightening conditions, it is proposed that the workpiece (1), which is held on the end side in mounting heads (6), is bent out by means of the mounting heads (6) in directions changing at least in predetermined angular ranges, and bent back again.

Claims

1. A method for straightening a workpiece with a longitudinal axis and longitudinal ends, said method comprising: holding the workpiece with mounting heads each holding a respective longitudinal end of the workpiece; and one or more bending steps each comprising bending the workpiece out from a starting position transversely to the longitudinal axis only by applying bending moments via the mounting heads; and then bending the workpiece back to the starting position only by applying bending moments via the mounting heads; wherein the mounting heads in the one or more bending steps move so that, relative to the workpiece, the bending out and bending back is in more than one direction transverse to the longitudinal axis.

2. The method according to claim 1, wherein the bending out and the bending back of the workpiece are in directions that change continuously.

3. The method according to claim 2, wherein the bending out and the bending back of the workpiece is symmetrical to a center plane perpendicular to the longitudinal axis.

4. The method according to claim 2, wherein the bending out and the bending back of the workpiece is performed during a rotation of the workpiece about the longitudinal axis by the mounting heads.

5. The method according to claim 1, wherein the bending out and the bending back of the workpiece is symmetrical to a center plane perpendicular to the longitudinal axis.

6. The method according to claim 5, wherein the bending out and the bending back of the workpiece performed during a rotation of the workpiece about the longitudinal axis by the mounting heads.

7. The method according to claim 1, wherein the bending out and the bending back of the workpiece is performed during a rotation of the workpiece about the longitudinal axis by the mounting heads.

8. A device for straightening a workpiece with a longitudinal axis and two longitudinal ends, said device comprising: two mounting heads configured to be aligned coaxially to each other, and supported to be adjustable relative to one another in a direction of a coaxial straightening axis; said mounting heads each receiving a respective longitudinal end of the workpiece; wherein each of said mounting heads is mounted so as to be rotatable about two pivot axes that extend transversely to the coaxial straightening axis; and wherein each of said mounting heads is driven so as to rotate about said pivot axes and apply bending forces to the workpiece held by the mounting heads in different directions transverse to the coaxial straightening axis.

9. A device for straightening a workpiece with a longitudinal axis and two longitudinal ends, said device comprising: two mounting heads configured to be aligned coaxially to each other, and supported to be adjustable relative to one another in a direction of a coaxial straightening axis; said mounting heads each receiving a respective longitudinal end of the workpiece; wherein each of said mounting heads is mounted so as to be rotatable about a respective pivot axis extending transversely to the coaxial straightening axis, and the mounting heads are connected with a drive rotating the workpiece about said longitudinal axis such that the mounting heads apply bending forces to the workpiece held by the mounting heads in different directions transverse to the coaxial straightening axis.

10. The device according to claim 9, wherein the pivot axes of the mounting heads extend in parallel relative to each other.

Description

BRIEF DESCRIPTION OF THE INVENTION

(1) In the drawing, the subject invention is shown by way of example, wherein:

(2) FIG. 1 shows a device according to the invention for straightening a workpiece with a pronounced longitudinal axis in a partly sectional, schematic side view,

(3) FIG. 2 shows this device in a plan view,

(4) FIG. 3 shows a construction variant of a straightening device according to the invention in the region of one of the two mounting heads in a schematic side view, and

(5) FIG. 4 shows the device of FIG. 3 in a plan view.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

(6) The device for straightening a workpiece 1, e.g. a pipe, comprises according to FIGS. 1 and 2 a frame 2 with guides 3 for two carriages 4, which each carry a turntable 5 for receiving a mounting head 6. The mounting heads 6 are thus rotatably mounted on the carriage 4 about a pivot axis 7, which extends transversely to the guides 3 and is indicated with the dash-dotted lines, and can be pivoted out by means of pivoting cylinders 8 from a starting position, which is determined by the mutually coaxially aligned mounting heads 6. This coaxial straightening axis of the mounting heads 6 extending in the direction of the guides 3 is denoted by reference numeral 9.

(7) The two mounting heads 6, which comprise a rotatably mounted workpiece holder 10, are each associated with a drive 11 for the workpiece holder 10, so that the workpiece 1 can be driven in rotation about its longitudinal axis from its two ends.

(8) For mutual displacement of the carriages 4, a spindle drive 12 is provided with two opposing spindle sections which are driven by a drive 13, so that the carriages 4 can be moved apart or towards each other.

(9) Between the carriage 4, a transverse conveyor 14 is provided, which has receptacles 16 movable along rails 15 for workpieces 1 to be straightened. The workpieces 1 to be straightened can thus be introduced into the device when the carriages are moved apart via the transverse conveyor 14 in order to be received by the mounting heads 6 by moving the carriages 4 together. In order to ensure that the straightening process cannot be hindered by the receptacles 16 of the transverse conveyor 14, these receptacles 16 can be lowered and retracted from the region of the straightening device. In the illustrated embodiment, the receptacles 16 are designed in this case as actuating pistons which can be pressurized by a pressure medium, which pistons are provided in drivers 17 movable along the rails 15. The actuator for the driver 17 is not shown for reasons of clarity.

(10) For straightening the workpiece 1, it is introduced into the straightening device in the described manner by means of the transverse conveyor 14 and is received by the mounting heads 6. After an extension of the driver 16 from the straightening region, the straightening process can be initiated in that first the drive 11 is turned on for the rotation of the workpiece 1 about its longitudinal axis. A bending moment can then be applied to the rotating workpiece 1 via the longitudinal ends gripped by the mounting heads 6, specifically by a corresponding actuation of the pivoting cylinders 8, so that the mounting heads 6 are pivoted out of the coaxial straightening axis 9 about the pivot axes 7. At the same time, the two mounting heads 6 must be pulled via the spindle drive 12 against each other in order to take into account the shortening of the mutual mounting head distance caused by the bending of the workpiece 1. After bending out from the starting position predetermined by the coaxial straightening axis 9, it is bent back into the starting position with continuous rotation of the workpiece 1, wherein the mounting heads 6 are pivoted back via the pivot cylinders 8 and at the same time the carriages 4 are moved apart again. On reaching the starting position, the straightening process is completed. The workpiece 1 can be removed from the straightening device via the transverse conveyor 14 once the workpiece 1 has been released by moving the mounting heads 6 apart.

(11) According to the embodiment of FIGS. 3 and 4, the two mounting heads 6 are driven not only about a pivot axis, but are driven about two respective pivot axes 18, 19 which preferably stand perpendicularly to each other and extend transversely to the straightening axis 9, so that a rotary drive for the workpiece 1 about its longitudinal axis can be dispensed with and still a corresponding bending moment can be applied via the mounting heads 6 in continuously changing directions. For this purpose, the mounting heads 6 are mounted in the manner of a cardan joint in a frame structure 20, the bearing body 21 comprises a shaft 22 which forms the pivot axis 18 and carries the mounting head 6. On the shaft 22, two diametrically opposite stub axles 23 are attached to which an actuator in the form of pivot cylinders 24 engages, so that the shaft 22 and thus the mounting head 6 can be rotated via the actuating cylinders 24 about the pivot axis 18.

(12) The mounting heads 6 are additionally rotatably mounted on the stub axles 23, which thus determine the pivot axis 19. For the rotary drive about the pivot axis 19, two pivoting cylinders 25 are again provided, which are articulated on the one hand on the mounting head 6 and on the other hand on the shaft. The mounting head 6 which is non-rotatably held in relation to the shaft 22 can therefore be additionally pivoted about the stub axle 23. Thus, the conditions are created to continuously bend out the workpiece 1 to be straightened in all directions and back again, without having to drive the workpiece itself in a rotating manner.