GB2446921A

GB2446921A - Deformation compensation in means for clamping material to be stretched

Info

Publication number: GB2446921A
Application number: GB0801827A
Authority: GB
Inventors: Walter Kirchner; Gunter Halleck; Karsten Busch
Original assignee: SMS Meer GmbH
Current assignee: SMS Group GmbH
Priority date: 2007-02-24
Filing date: 2008-01-31
Publication date: 2008-08-27
Anticipated expiration: 2028-01-31
Also published as: RO125962B1; ITMI20080255A1; CN101249539B; GB2446921B; DE102007009139B3; RO125962A2; RU2008106945A; GB0801827D0; RU2379146C2; CN101249539A

Abstract

Apparatus for stretching and straightening rolled or pressed material, particularly sheets or plates, includes a clamping head 1 having a clamping jaw 5 defined by a plurality of flat elements 3, 4 distributed over the working width of the head and arranged adjacent to one another perpendicularly to the plane 2 of the material. The elements are connected together by a members 6, 7, 8 which form a box structure stiff in bending. The gap between the elements and the box structure is filled by fixed wedge surfaces 13 and movable wedges 10 under continuous pressure from piston and cylinder units 11. Should the gap increase due to tension force F from the clamped material the units 11 provide automatic adjustment by moving the wedges 10 to fill the increased space.

Description

DEFORMATION COMPENSATION IN CLAMPING MEANS FOR CLAMPING MATERIAL

TO BE STRETCHED

The present invention relates to a clamping means for clamping rolled or pressed material, particularly sheets or plates, to be stretched and straightened by stretching and straightening apparatus, and to a method of operating clamping means for that purpose.

In a known clamping head of a plate stretcher a clamping jaw is composed of segments which are arranged vertically with respect to a plane of material to be stretched and which are provided with C-shaped openings and clamping devices necessary therein for gripping the plate or the sheets.

A clamping head is known from, for example, DE 101 13 668 B4, in which sheet segments are divided horizontally to the plane of stretching and engage in shape-locking manner around an inwardly disposed further component as clamping jaw of the clamping head by complementary halves above and below the plane of stretching. The damping head thus consists of several components which for enhanced absorption of force are made of different materials, wherein the divided segments and the clamping jaw are connected together by a biased system consisting of a tie rod and a pressure member. The individual segments and the clamping jaw are thus tightened to form a box which is stiff in bending and transversely, whereby gaping of the individual components is to be prevented.

In addition, the divided segments and the clamping jaw are connected together by way of lock-like segments arranged to be distributed above and below the stretching plane in the working region of the clamping jaw over the entire head width. These contribute to, inter alia, absorbing the spreading forces, which occur during a stretching process, and distributing them to the entire system.

The segments, which as explained above are firmly tightened together, and the box are, however, subjected to a further critical loading during the stretching or elongating process.

Due to the stretching force the segments are deformed in horizontal direction so that a gap or joint space arises between the segments and the bending box. A rise in stretching force also has the consequence of enlargement of the gap due to an accompanying elongation of the segments. %

If during the stretching process there is tearing of the plate to be stretched, the energy then liberated acts on the clamping head, which as a consequence and due to the gap hits against the box or impacts hard against this and thus may be damaged together with the box.

There is therefore a need for clamping means without the described disadvantages, in which, in particular, there is secure tightening of a clamping head formed by segments.

According to a first aspect of the invention there is provided a method of operating a plate stretcher for stretching and straightening rolled or pressed material to be stretched, particularly sheets or plates, in which a clamping head consists of a plurality of segments, which are distributed over the working width of the clamping head and arranged adjacent to one another perpendicularly to the plane of the material to be stretched and which are formed on their side facing the working region with a clamping jaw extending over the entire width of the clamping head and are tightened on their side remote from the working region by a biased system to form a box stiff in bending, characterised in that a biasing means acted on by a permanently present pressure is automatically re-adjusted in a gap which arises between the clamping head and the bending box in dependence on the operating force caused.by the stretching.

It is thus advantageously achieved that the segments which may deform due to the stretching process -in this connection a progressing elongation of the segments takes place with increasing operating force -are continuously adjusted.

This system, in particular the clamping head having segments, the biasing means and the box, automatically achieves its tightness by the biasing means re-adjusting in the gap and automatically maintains this biasing force. At no time of the stretching process does a gap or a separating space arise between the segments and the bending box, so that damage due to shocks and/or impacts as a consequence of the liberated energy in the event of plate tearing is effectively prevented.

According to a second aspect of the invention there is provided a device for operating a plate stretcher for stretching and straightening rolled or pressed material to be stretched, particularly sheets or plates, in which a clamping head consists of a plurality of segments, which are distributed over the working width of the clamping head and arranged adjacent I' to one another perpendicularly to the plane of the material to be stretched and which are formed on their side facing the working region with a clamping jaw extending over the entire width of the clamping head and are tightened on their side remote from the working region by a biased system to form a box stiff in bending, particularly for carrying out the method according to the first aspect of the invention, characteriSed in that a wedge-shaped tightening element acted on by a permanently present pressure force is arranged between the clamping head and the box.

As soon as a gap or a joint space between the clamping head and the box forms under the operating force, which acts in horizontal direction of the stretching plane, due to the stretching process this is closed by automatic displacement of the wedge-shaped clamping means, which is termed uwedgeu in the following. For this purpose the wedge is acted on with pressure by, for example, a setting means, preferably a pneumatic piston-cylinder unit.

Before the stretching process the wedge is disposed by its free end at the joint location between the clamping head and the box. It is loaded with pressure by the piston-cylinder unit so that it is continuously pressed into the gap, which enlarges due to the increasing stretching force, between clamping head and box. The wedge is displaced in the gap until the maximum operating force of the stretching process is attained, i.e. a maximum elongation of the segments of the clamping head and thus a largest possible gap dimension have been reached. Clamping head and bending box are now biased in dependence on the maximum operating force which is produced.

If end surfaces, which face the clamping head, of the box each have a wedge surface complementary with the wedge, wherein the respective slight inclination of the complementary wedge surfaces produces a self-locking of the wedge connection, the clamping head and the box remain biased by operating force.

An example of the method and an embodiment of the clamping means of the present invention will now be more particularly described with reference to the accompanying drawings, in which: Fig. I is a cross-section of clamping means embodying the invention; and Fig. 2 is a detail view, to enlarged scale, of a joint location between a clamping head and box structure in the clamping means of Fig. 1.

Referring now to the drawings there is shown a clamping head I of a plate stretcher, the head consisting of a plurality of segments 3, 4 which are arranged adjacent to one another perpendicularly to the stretching plane 2 and which engage in shape-locking manner* around a C-shaped clamping jaw 5 (not illustrated in more detail) over its entire width. The jaw as a rule consists of fine-grain constructional steel. Clamping devices necessary for clamping of material to be stretched are arranged in the C-shaped opening, which faces the working region, of the clamping jaw 5. A box 9 stiff in bending and composed of shells 6, 7 (upper shell and lower shell) extending transversely to a stretching plane 2 is formed above and below the segments 3, 4. The two shells 6, 7 are tightened together by way of tie rods 8, whereby the individual segments 3, 4 and the clamping jaw 5 bounded by these are connected together in force-locking manner.

A respective wedge-shaped tightening element 10 or wedge is arranged at the upper and lower junction between the clamping head I and the box 9 formed from the shells 6, 7 and the tie rods 8. A respective piston-cylinder unit 11, which is preferably pneumatically controlled in drive, is associated as setting means with each of the wedges 10.

In addition, the end walls 12, which face the clamping head 1, of the box 9 are provided with inclined or wedge surfaces 13, for example wedge inserts, complementary with the wedges 10. The wedges 10 and the wedge surfaces 13 together provide a firm, but releasable tightening, wherein the slight inclination of the wedges 10 and the surfaces 13 produces a self-locking effect.

Before the stretching process of material, which is to be stretched and which is not illustrated, the wedges 10 are disposed outside or at the beginning of the joint location between clamping head I and box 9 in a zero position, i.e. they are not disposed in pressurable connection with the wedge surfaces 13 and are disposed under pressure loading by way of the piston-cylinder units 11 controlled in drive.

During the stretching process of the material an elongation of the segments 3, 4 of the clamping head I takes place due to the stretching or operating force F acting in horizontal direction, whereupon a gaps arise between the segments 3, 4 and the wedge surfaces 13 of the bending box 9. These gaps are closed by the wedges 10 which are disposed under pressure and thus automatically displace. The bias between the clamping head I and the bending box 9 is maintained through the compensation for the enlarging gaps.

If during the stretching process the maximum stretching or operating force F is reached, whereby the segments 3, 4 experience their largest possible elongation, the wedges 10 have, in dependence thereon, displaced into the respective end positions in the now-present maximum gap openings.

The clamping head I or the segments 3, 4 and the box 9 are now biased by operating force. The maximum biasing force in this connection is maintained due to the self-locking between the flat wedge angles of the wedges 10 and the wedge surfaces 13. A further spreading apart of the clamping head I and the box 9 due to the wedges 10 loaded by pressure does not occur, since the piston rods of the piston-cylinder units 11 have a stroke limitation.

A free gap between the segments 3, 4 and the bending box 9 does not arise at any time in the stretching process so that no impacts or shocks can arise in the event of plate tearing, since the clamping head cannot spring back. ) *1

Claims

1. Clamping means for clamping rolled or pressed material which is to be stretched and straightened by stretching and straightening apparatus, the clamping means comprising a clamping head formed by a plurality of segments which are arranged adjacent to one another over a working width of the head and perpendicularly to a given plane of material clamped by the clamping means and which at sides thereof intended to face a working region define a clamping jaw extending over the working width of the head, connecting means connecting the segments together at sides thereof remote from the working region and forming a box structure stiff in bending, wedge tightening means acting between the clamping head and box structure and pressure loading means to provide continuous pressure loading of the tightening means for displacement thereof to compensate for change in a gap produced between the clamping head and box structure due to forces acting on material clamped by the clamping means.

2. Clamping means as claimed in claim 1, the pressure loading means comprising a piston-cylinder unit.

3. Clamping means as claimed in claim 1 or claim 2, wherein the box structure is provided with a wedge surface co-operating with and substantially complementary to the wedge tightening means.

4. Clamping means as claimed in claim 3, wherein the wedge surface is provided on a wedge insert.

5. Stretching and straightening apparatus provided with clamping means as claimed in any one of the preceding claims.

6. A method of operating clamping means for clamping rolled or pressed material which is to be stretched and straightened by stretching and straightening apparatus, the clamping means comprising a clamping head formed by a plurality of segments which are arranged adjacent to one another over a working width of the head and perpendicularly to a given plane of material clamped by the clamping means and which at sides thereof intended to face a working region define a clamping jaw extending over the working width of the head, connecting means connecting the segments together at sides thereof remote from the working region and forming a box structure stiff in bending and wedge tightening means acting between the clamping head and box structure, comprising the step of providing continuous pressure loading of the tightening means for displacement thereof to compensate for change in a gap produced between the clamping head and box structure due to forces acting on material clamped by the clamping means.