GB2251198A

GB2251198A - Clamp for steel bar shears

Info

Publication number: GB2251198A
Application number: GB9122696A
Authority: GB
Inventors: Albert Eck
Original assignee: Eumuco AG fuer Maschinenbau
Current assignee: Eumuco AG fuer Maschinenbau
Priority date: 1990-10-25
Filing date: 1991-10-25
Publication date: 1992-07-01
Anticipated expiration: 2011-10-25
Also published as: IT1251634B; ITMI912823A1; JPH04283015A; ITMI912823A0; GB2251198B; DE4033931A1; GB9122696D0; DE9014775U1; DE4033931C2; FR2668406A1

Description

12-311 13 Holding apparatus for steel bar shears The invention relates to

a holding apparatus for steel bar shears for shearing off exact lengths of steel bar and billet material for use as blanks for massive forming. Such shears generally have a driven roller table for feeding the billet or the like through the work space of the shears and a clamp for fixing the billet against a counter-bearing; the billet is fed by means of a feed device such as an axially movable feed tongs mechanism or clamp.

Such steel bar shears are known through DE-PS 34 14 233, in which the feed device has a fixed clamp and a movable clamp. The feed device is provided with a continuously adjustable stroke-limiting apparatus with a servomotor, with which apparatus the length of the sections to be sheared off can be adjusted. The fixed-position clamp is mounted on the shears for gripping the billet and its jaws are provided with restoring springs acting in the axial direction. These restoring springs take up the axialmovement of the rod which occurs during the shearing cut in order to eliminate the influence of varying three-dimensional deformation when cutting different section lengths.

The restoring springs have a double function. They ensure, on the one hand, that the rod can take up the axial movement during the shearing cut in order subsequently to reach the original position again. In addition, the restoring springs cause the fixed clamp to grip the rod material with respect to the whole system in a play-free starting position. The restoration into the neutral central position occurs by way of helical springs which lie on the axis of the correction movement. Such a construction results in a certain structural complexity.

The invention aims by means of a further structural configuration to adapt the feed device to the deformed shape of the bar or billet material to be sheared in an even better way, that is, in a more flexible manner, for accurate shearing. In general terms the invention is distinguished in that the mounting of the clamp is effected by means of restoring spring bars.

Thus, according to the invention, there is provided a holding apparatus for steel bar shears for shearing off exact lengths.of steel bar or billet material, including a feed device in the form of an axially movable feed clamp, in which the mounting of the clamp is effected by means of restoring spring bars.

The bar or billet material to be transported tends to be bent within certain limits over its longitudinal axis and twisted in cross-section. The reproducibility of the rod feed is a basic pre-condition for achieving a weight-accurate shearing process. In this connection, geometrically well-defined clamping of the bar or billet cross-section is of fundamental importance. By means of the mounting of the parts of the feed device the clamp can be adapted to the current cross-sectional position quickly and in a manner such that it is restored again, by virtue of the spring bars. The spring bars, which preferably extend parallel to the feed axis, guarantee that the clamping plane can be displaced horizontally, vertically and angularly, i.e. in the circumferential direction of the cross-section, by a certain amount. This can be achieved in a comparatively simple manner in that the holding support of the clamp is suspended as it were on gimbals and in a restoring manner. As a result, the feed device can follow the irregular course of the bar and billet material, in consequence of bending and also twisting movements, in a perfect and reliable manner; according to the variation of the cross-sectional form over the length restoration of the feed device occurs automatically. The clamp can easily adapt to the current cross-sectional position. The fact that the clamping plane is constructed so as to be displaceable horizontally, vertically and in the circumferential direction of the cross-section by means of the spring bars ensures this. Geometrically well-defined clamping of the bar and billet cross-section is guaranteed by means of the spring bars.

According to a further feature of the invention, the spring bars are respectively arranged in pairs, generally symmetrically about the workpiece axis. Advantageously, in the case of the movable tongs one spring bar pair is provided in parallel defining a horizontal plane and a further spring bar pair is provided defining a vertical plane. The fixed tongs can be supported by means of a spring bar pair arranged in a horizontal position, this then being sufficient if the clamp is located close to the shears.

The arrangement of the spring bars can advantageously be effected in such a way with the movable clamp that the vertically arranged spring bar pair is installed between the billet feed drive and an intermediate plate and the horizontally placed spring bar pair is installed between the intermediate plate and the movable clamp. For the stationary clamp, a spring bar pair can be provided between the frame and the clamp.

An embodiment of the invention will now be described in greater detail with the aid of the accompanying drawings, in which:

Figure 1 shows a holding apparatus in accordance with the invention, in elevation; Figure 2 is a view of the apparatus of Figure 1 in the direction of the arrow II.

Figure 3 shows a section through the apparatus of Figure 1 according to the line III-III; and Figure 4 is a plan view of the apparatus of Figure 1 in the direction of the arrow IV.

The feed device 1 for shearing off sections of exact lengths of billet material and the like has a stand 2 which is composed of a front stand portion 3 5 and a rear stand portion 4 and also cross-members 5. The feed apparatus contains clamping tongs 6 which can be moved along the longitudinal axis and stationary clamping tongs 7. The bar or billet material 8 which is to be transported is supplied to the feed apparatus by way of a preceding roller table 9 until it reaches the region of the movable clamp 6, whereupon the latter takes over the further rod transport.

The bar to be processed is then clamped by the clamp 6 between the plates 11 arranged at 450 to the vertical and a hydraulic cylinder 12 mounted in a cross-member 13, as shown in Fig. 3. In the opened state of the clamp the cross-member 13 is supported on stops 14. The stationary clamp 7, shown in Fig. 2, have corresponding components, namely a cross-member 13a with incorporated inclined plates 11a and a hydraulic cylinder 12a for clamping the workpiece. The cross-members 13 and 13a can be lifted by means of a hydraulic cylinder 15 and 15a respectively, something which can be necessary when threading the bar into the blade area of the shears.

A transporting carriage 17 is mounted so as to be displaceable in the longitudinal direction of the apparatus. To this end the carriage plate 17 is fixed at each side, e.g. by welding, to a cylindrical bushing 18; each bushing 18 in turn slides on a guide 19 fixedly mounted by means of a boss portion 20 on the side portions 3 and 4 of the stand. The transporting carriage 17, 18 is driven by way of a servo-hydraullc piston-cylinder unit 21 and executes a stroke movement which corresponds to the length of the sections to be sheared. A second carriage plate 17a may be provided for reinforcement, as shown in Fig. 4.

In the case of the feed device shown the support and restoration of the movable clamp 6, and also the fixed clamp 7, is effected by means of spring bars. In the case of the movable clamp 6 the spring bars are arranged in two pairs, namely the pair 23, 24 forming a vertical plane and the pair 25, 26 forming a horizontal plane. In the case of the fixed clamp 7, two spring bars 28, 29 in a horizontal plane are considered to be sufficient, as this clamp is located comparatively close to the shears and there the horizontal deviations are only very small. In the case of the movable clamp 6, the vertical spring bar pair 23, 24 is provided between the transporting carriage 17 and an intermediate plate 31, whilst the spring bar pair 25, 26 in the horizontal plane is arranged between the intermediate plate 31 and the movable clamp 6. The spring bars 28, 29 for the fixed clamp extend between the stand 2 and the clamp 7. The intermediate plate 31 can be displaced by way of the spring bars 23, 24 slightly in the horizontal direction, while by way of the connection via the spring bars 25, 26 the movable clamp 6 can move slightly in the vertical direction. Tiie slight movement of the clamp is made possible as a result of the length of the spring bars.

As a result of the spring bars there is a kind of Cardanic suspension of the movable clamp, and also of the stationary clamp, with restoration. By virtue of the spring bars arranged in pairs the clamp can be displaced in the peripheral direction of the crosssection of the rod to be sheared. In the spring bars there then arise, according to the position of the rod cross-section, the bending and/or torsional stresses with automatic restoring force. After release of the clamping force, caused by return travel of the pistoncylinder unit 12, 12a of the relevant hydraulic 6cylinder, the clamps are automatically set back into the neutral horizontal and rotational position. In the released position, the clamps lie on the stops 14, 14a in a vertical position. In this way the guarantee is given that geometrically well-defined clamping of the bar or billet cross-section will occur. The clamps can be adapted to the current cross-sectional position of the workpiece. The clamping plane is displaceable horizontally, vertically and in the peripheral direction of the cross-section of the work piece and can be restored automatically into the neutral central position. This holds good with the exception of the horizontal displacement both for the moveable clamp and for the stationary clamp. This apparatus makes it possible to be able to effect weight-accurate shearing.

It will be appreciated that the diagrams are schematic only and any suitable generally longitudinal spring means could be used to fulfil the object of the invention.

Claims

1. Holding apparatus for steel bar shears for shearing off exact lengths of steel bar or billet material, including a feed device in the form of an axially movable feed clamp, in which the mounting of the clamp is effected by means of restoring spring bars.

2. Holding apparatus according to claim 1, in which the spring bars are respectively arranged in pairs.

3. Holding apparatus according to claim 2, In which one spring bar pair is provided in a horizontal plane and a further spring bar pair is provided in a vertical plane.

4. Holding apparatus according to claim 3, in which the spring bar pair which lies in the vertical plane is arranged between a driven carriage and an intermediate plate and the horizontal pair is arranged between the intermediate plate and the movable clamp.

5. Holding apparatus according to any preceding claim, in which the apparatus also includes a stationary clamp, supported by means of a spring bar pair arranged in a horizontal plane.

6. Holding apparatus according to claim 5, in which the spring bar pair for the stationary clamp is arranged between the frame of the apparatus and the stationary clamp.

7. Holding apparatus according to any preceding claim and further including a driven roller table for feeding the billet or the like through the work space of the shears and having a holding-down clamp for fixing the billet or the like against a holding-down clamp counter-bearing during shearing.

8. A holding apparatus substantially as described herein with reference to the accompanying drawings.