DE20309207U1 - Computer controlled machine for the programmable bending of tube or bar sections - Google Patents

Abstract

The computer controlled (14), CNC, machine has a carriage (12) that moves linearly on guide bars. Mounted on the carriage is a controlled bending tool (5) that rotates. One end of a tube is clamped (7) to the carriage and the other clamped to the frame (8). The slide and bending tool are hydraulically powered and controlled by electro hydraulic valves (15,16).

Description

Fluidtechnik GmbH Friedensstrasse 14
99887 Georgenthal

10

Device for bending pipes and profiles
15

The invention relates to a device for bending pipes and profiles with small bending radii without the use of bending mandrels for mechanical stabilization of the profile cross-section.

When producing bends on pipes and profiles, the introduced bending moments and the resulting stresses cause an undesirable deformation of the profile geometry. Flattening occurs, which in extreme cases can lead to buckling or tearing of the material being bent.
For pipes with special strength requirements, it is necessary to avoid flattening of the original profile as far as possible.
This is achieved by supporting the pipes from the inside in the bending zone by mechanically inserted mandrels.

In cases where it is not possible to insert mandrels, other known methods use the compensation of the tensile force generated in the bending zone by superimposing tensile force by superimposing compressive stresses in order to prevent the deformation of the material to be bent or to limit it to insignificant values.

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According to the invention, the effective tensile stress shift is achieved by the device achieving a geometrically defined shift of the neutral fiber in the bending zone. This takes place over the course of the entire bending process and enables a continuous change adapted to the overall stress state.

Example:

A carriage 12 which can be moved linearly as shown in Figure 1 carries the bending head 5 which is arranged to generate the bending moment and which is provided with a clamping cylinder 7 for fixing the workpiece 18 to the bending head 5.

The carriage 12 is moved hydraulically by feed cylinders 3 and 4 arranged on both sides. In the exemplary embodiment, the feed cylinders 3 and 4 also serve as carriage guides. For this purpose, they are connected to one another in parallel by cross connectors 1 and 2.

The cross connector 1 carries a base clamping cylinder 8, which firmly fixes the workpiece 18 to the cross connector 1.

The cross connector 1 is the reference point for the linear measurement with the position measuring system 9 and supports the forces resulting from the bending process of the slide 12. The movement of the slide 12 is recorded by the position measuring system 9, signal forms are formed by the evaluation electronics 1 and the evaluated signal is fed to a CNC control, as is the angle signal which is obtained via the angle measuring system 10 on the bending head motor.
The actuating movements, linear and rotary, are controlled by means of the hydraulic control valves 15 and 16 and supplied by a hydraulic pump and an electric drive.

According to Figure 2, the device is controlled in such a way that the leading pivoting movement of the bending head 5 generates a relative movement on the cross connector 1, so that a slip-free coupling of a rolling movement on a straight line is achieved.
The straight line tangential to the virtual bending radius defines

I··

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the position of the neutral fiber in the bending zone.

By electronically defining the rolling geometry, the neutral fiber

in the bending profile.

-A-

LIST OF REFERENCE SYMBOLS

I Cross connector 2 Cross connector

3 left feed cylinder

4 right feed cylinder

5 Bending head

6 Bending head motor 7 Clamping cylinder

8 basic clamping cylinders

9 electronic position measuring system

10 Angle measuring system with evaluation electronics

I1 Evaluation electronics of the position measuring system 12 slides

13 Amplifiers

14 CNC control

15 hydraulic control valve for bending head control

16 hydraulic control valve for slide control 17 hydraulic pump with electric drive

18 Workpiece

Claims (4)

1. Device for bending pipes and profiles, characterized in that the device contains means with which stresses arising in the bending zone can be compensated by geometrically coupling a rotational movement to a slip-free coupled translational movement and the resulting displacement of the neutral fiber in a defined form. 2. Device according to claim 1, characterized in that the slip-free geometric coupling of the rotary and translatory movements is achieved by controlling the movements via axis drives, the control variables of which are calculated by a CNC control system in evaluation of the bending angle and path information. 3. Device according to claim 1 or 2, characterized in that a bending head ( 5 ) is connected to a linearly arranged carriage ( 12 ) and the linear drive simultaneously takes over the guidance of the system. 4. Device according to one of the preceding claims, characterized in that the support of the translational forces relative to the workpiece simultaneously forms the origin of the measuring system for the translational movement and largely excludes external influences on the measurement result, such as frame and workpiece deformations.