GB2087285A - Apparatus for machining longitudinally-extending workpieces on a machine tool having a coordinate table - Google Patents

Abstract

An apparatus for machining longitudinally-extending workpieces (17) on a machine tool includes a coordinate table (T) preferably mechanically controlled for the feed movement of the workpieces. The coordinate table (T) has gripper mean (10) for the workpiece (17), with which the workpiece is fed in direction (X). In the main feed direction (X) there is a workpiece stop (2,4) for the forward end of the workpiece and which is pivotable out of the region of movement of the workpiece. Between the stop (2,4) and the gripper (10), an auxiliary clamping device (20) likewise provided with driven gripper means (12,12',15) adapted to the contour of the workpiece is arranged. This auxiliary clamping device (20) is secured at a predetermined distance (a) from the operative machining tool (21) which is on the part of the coordinate table movable in the second feed direction (Y-axis). Piercing and shearing tools (21,25) are mounted on a turret. <IMAGE>

Description

SPECIFICATION Apparatus for machining longitudinally-extending workpieces on a machine tool having a coordinate table This invention relates to an apparatus for machining longitudinally-extending workpieces on a machine tool having a coordinate table for the feed movement of the workpiece, in which the coordinate table includes clamping means for the workpiece in two directions of movement.

Longitudinally-extending profiled sections, namely long and narrow workpieces, such as rails, rods, longitudinally-extending angle-irons, U-sections or the like, which are usually made from drawn or rolled rod material, have to be machined in relatively large numbers to the most varied dimensions on machine tools, and in particular have to be provided with apertures or similar pressed features. For instance, bus bars of copper are required with different cross-sections and lengths. It is common for such longitudinally-extending workpieces as a rule to have to be provided with only a few apertures, in which most cases also lie along a line.

Only occasionally does it happen that such apertures are arranged at different distances from the longitudinal edges. It is usual to machine such longitudinally-extending workpieces, and particularly bus bars, in combined piercing and cutting tools, which are installed on eccentric presses. It is usual for the different aperture spacings to be produced with the aid of adjusable abutment stops. For this purpose, finishing sections are installed or appropriate tool combinations are made up by means of punch hoops.

These known devices and their methods of operation are either very high in labour costs or very capital-expensive, so that in practice it is desirable to machine such longitudinally-extending workpieces on piercing presses with numerically-controlled coordinate tables. With the clamping arrangements installed previously on such piercing presses or their coordinate tables, such longitudinally-extending workpieces and particularly the rail or rod-shaped ones cannot readily be positioned since the space between the lower tool and the upper tool is limited and consequently parts which exceed the usual sheet-metal thickness of 5 or 6 mm cannot be clamped and brought into the region of the operative tool. However, such longitudinally-extending workpieces, for instance bus bars, frequently have larger dimensions.

It is an object of the invention to provide an apparatus of the kind mentioned initially, with which such longitudinally-extending workpieces can be effectively clamped and moved on the numericallycontrolled coordinate table.

In accordance with the invention, on that clamping means of the coordinate table movable in the main feed direction (X-axis), there is provided, on the side facing the machining tool zone, a workpiece stop pivotable out of the region of movement of the workpiece and arranged to be abutted by the forward end of the workpiece, and, on the side facing away from the machining tool zone, a main clamping device with driven gripper means adapted to the contour of the workpiece, and also, between the workpiece stop and the main clamping device, an auxiliary clamping device likewise provided with driven gripper means adapted to the contour of the workpiece, and secured at a prescribed distance from the operative machining tool on that part of the coordinate table in the second feed direction (Yaxis).

With the aid of such a workpiece stop and such clamping arrangements it is possible reliably to secure longitudinally-extending workpieces to the coordinate table and then shift these in the way desired for the machining operations. This enables the following advantageous mode of operation to be used: The workpiece is moved through the opened gripper means of the clamping devices from the side of the coordinate table facing away from the machining tool zone, until the end of the workpiece contacts the stop. Using the main clamping device, the workpiece is then secured and the stop is pivoted out of the region of movement of the workpiece. Thereafter, the coordinate table with the secured workpiece can then be moved in the main feed direction (X-direction) until the position required for the machining operation has been attained.Thereafter, the gripper means of the auxiliary clamping device is actuated and thus the workpiece is held fast in this position, until the desired operations by the tool have been completed. Thereafter, the gripper means of the auxiliary clamping device is released and the workpiece can then again be moved over the coordinate table in the longitudinal direction, whereupon the stated sequence is again followed. Depending upon the programming of the coordinate table, it is possible, by means ofthetwo clamping devices to carry out the feed movements necessary in the second feed direction (Y-axis) for machining operations on the workpiece. The most varied longitudinally-extending workpieces can be secured to the coordinate table of the machine tool and can be moved upon it without limitation.If the space remaining between the clamping devices on advance in the main feed direction is no longer sufficient, the workpiece can be held by means of the auxiliary clamping device, the main clamping device can be released and taken back in the direction opposite to the main feed direction, whereafter it can then again be brought into engagement with the workpiece and the prescribed sequence of steps carried out.

A particularly advantageous embodiment of the workpiece stop is one in which it comprises a support securable to the clamping means and a pivot member carrying an abutment surface for the workpiece and pivotable on the forward end of this support, the pivot member being pivotable by means of a drive mechanism arranged on the support. In this way, a particularly simple and easily-operatable arrangement and support of the stop in the region of the workpiece is provided. For the drive mechanism, one can use pneumatic or hydraulically-driven piston/cylinder units, both of which ensure simple control on the one hand and reliable pivoting movement on the other hand.

A particularly suitable form of the clamping arrangement is provided in a preferred embodiment of the invention, in which the main and auxiliary clamping devices each comprise a base member securable to the clamping means of the coordinate table and gripper means comprising a clamping member longitudinally-movable between guides on the base member by means of a drive mechanism, the clamping member clamping the workpice between a supporting surface formed on it and adapted to the contour of the workpiece and associated abutment surfaces on the base member. This mode of construction, with a simple construction and simple operation, enables easy introduction of the workpiece and a simple and more reliable securement of it.

Suitably, the abutment surfaces are formed by the front end faces of the guide formed as fork-shaped projections of the base member, and the clamping surface is formed by a rear wall of a gripper projection provided on the clamping member. This mode of construction is simple, requires few and easily-operated constructional elements and can be correspondingly adapted to the existing contour of the workpiece.

A simple feed movement of the clamping member by means of the drive mechanism leads to reliable securement of the workpiece. The drive mechanism of the clamping member is thus advantageously arranged on the base member. For the drive mechanism, pneumatically or hydraulically-driven piston/cylinder units can be used, which in a particularly reliable and simple way effect the securing and release movements of the clamping member.

If longitudinally-extending workpieces of very different width have to be machined, then preferably a shim member is provided inserted against the clamping surface for reducing the gripping width of the gripper means. By this means the stroke of the clamping member and its drive are restricted and the cycle time of the drive mechanism can thus be kept very small, since the driving member of this mechanism need only operate over a very short path.

For a reverse movement of the main clamping device, which is necessary with too close an approach of the two clamping devices one to the other, it is also of advantage if at least one of the clamping devices carries a proximity switch member which is actuated at a prescribed separation of the clamping devices. Thus a safety device is provided, in order to prevent too close an approach of the clamping devices to one another. Actuation of the switch member, particularly an electric switch, can be employed to prevent further travel of the workpiece in the main feed direction and can also trigger appropriate reversal and return movement of the main clamping device.

These and other features and advantages of the invention are given in the following description of a preferred embodiment of the invention, taken in conjunction with the drawings. The drawings are substantially schematic representations and show only the parts of a machine tool necessary for explaining the invention. In the particular embodiment, a revolving piercing press with a numericallycontrolled coordinate table is shown.

In the drawings: Figure 1 is a schematic plan view of the essential parts of the machine tool with the apparatus according to the invention; Figures 2 and 2a show a side view and a plan view respectively of the workpiece stop of the apparatus according to the invention; Figures 3, 3a and 3b show a side view, plan view and sectional view on the line A-A in Figure 3a respectively of the main clamping device of the apparatus according to the invention; the additional clamping device is constructed in a corresponding manner.

The apparatus according to the invention, as well as the associated machine tool, here a revolving piercing press, as well as its coordinate table, are represented only diagrammatically in Figure 1, the various parts being indicated to the extent that they enable explanation of the invention.

The tool region of the machine tool is indicated at W, in the present case the turret plate of a revolving piercing press with, inter alia, tools 21 and 25 which will be further described below. Within the region of the machine tool lying to the left in Figure 1, a coordinate table T illustrated generally and only in principle is indicated.

On a clamping rail 1 of the coordinate table, the rest of which is not illustrated, on the side facing the machining tool zone W, a workpiece stop, which is indicated generally at 2 and is pivotable out of the region of movement of the workpiece, is secured. On the side away from the machining tool zone W, likewise on the clamping rail 1 of the coordinate table T, a main workpiece clamping device is secured, which is indicated generally at 10, and as described further below is provided with driven gripper means adapted to the contour of the workpiece. Between the stop 2 and the main clamping device 10 an additional workpiece clamping device is arranged, which is indicated generally at 20. This additional clamping device 20 is arranged at a prescribed distance a from that tool of the tool zone W which is located in the operative, i.e. working, position.The additional clamping device 20 is located on a traverse 30, which inter-connects two sheet-metal supports 31 and 32 and is movable with these components only in the secondary feed direction. In Figure 1, the main feed direction is indicated by the arrow X, and the secondary feed direction by the arrow Y.

Figures 2 and 2a show the constructional arrangement of the workpiece stop indicated generally in Figure 1 at 2. By means of suitable clamping members 1a, a projecting carrier 3 is secured to the clamping rail 1 of the coordinate table. At its forward end this carrier 3 carries a pivotable abutment 4 pivotable about an axis 5 and defining an abutment surface 4'. Furthermore, on the carrier 3, a piston/ cylinder unit 6 serving as a pivotal drive for the abutment 4 and having a piston rod 8 is pivotably mounted at 7. The piston rod 8 is poivoted at 9 to a lever arm of the abutment 4. By means of the lever arm, which is represented by the line of connection between 5 and 9, on actuation of the drive mechanism 5 to produce a retraction stroke, there occurs a pivotal movement of the abutment 4 into the pivot position 40 illustrated in chain-dotted lines.

The main clamping device indicated generally at 10 is shown as to its constructional arrangement in Figures 3, 3a and 3b. A longitudinally-extending base member 11 is secured to the clamping rail 1, e.g. by means of clamping members 14. This base member 11 at its end remote from the clamping rail 1 carries a fork-shaped projection, which forms guides 12 and 12' for a clamping member 15 longitudinally-movable between these guides in grooves 13 and 13'.Theforward end faces 18 of the guides 12 and 12' and an appropriately directed, namely downwardly-facing, gripper projection with a clamping surface 19, form the gripper means of the clamping device 10. The clamping member 15 is driven by a pneumatic or hydraulically-driven piston/ cylinder unit 16 arranged on the base member 11.

On actuation of the drive unit 16 in the pull direction, the clamping member 15 is drawn back in the direction towards the clamping rail 1, and the workpiece 17, here a long and narrow bus bar of small cross-section, can then be clamped between the gripper members shown. If the workpieces to be machined are very different in width, then by using an insert member or shim 15', the clamping movement of the clamping member 15 and thus the stroke of the drive unit 16 can be restricted, this insert member 15' having the advantage that the cycle time for the drive unit 16 can then be kept small, since its piston only has to return through a minimal path length.The gripper means, in particular the abutment surfaces 18 and the clamping surface 19 on the rear wall of the gripper projection of the clamping member 15, or 19' on the insert member 15', can be adapted to the particular contour of the workpiece to be machined; in the case of the embodiment shown, this is the bar contour of the workpiece 17. If the workpieces comprise longitudinally-extending profiled rails or rods, the gripper elements and particularly the surfaces mentioned can be appropriately shaped, in order more reliably to hold such a workpiece.

The additional clamping device indicated generally at 20, for securement to the clamping rail 1, is formed in a similar manner to the main clamping device 10 according to Figures 3 to 3b.

The mode of operation of the apparatus described and illustrated is as follows: The longitudinallyextending workpiece 17 is moved in Figure 1 from the left through the opened clamping devices 10 and 20, i.e. with the clamping members 15 pushed forward, until the forward end of the workpiece 17 strikes the abutment surface 4' of the pivot arm of the stop 2. Then, the main clamping device 10 is actuated its clamping member 15 is drawn back, namely by means of the drive unit 16, and the workpiece 17 is held fast between the abutment surfaces 18 and the clamping surface 19 or 19'.Next, the pivot arm 4 of the stop 2 is provided out of the zone of movement of the workpiece 17, by actuation of the drive unit 6, into the pivot position 4 . The coordinate table T with the clamping rail 1 is then moved in its main feed direction, namely in the direction of the X-axis, until that position of the workpiece 17 is reached in which the first machining operation by means of the tool 21 in the tool region W is to be carried out, e.g. where the first hold is to be made. Once this position is attained, the auxiliary clamping device 20 is operated by corresponding actuation of its drive unit 16 and its clamping member 15, so that the workpiece 17 is then held both by means of the main clamping device 10 and also by means of the auxiliary clamping device 20.

Thereafter, the working stroke of the piercing press is effected and the first machining operation is carried out.

On completion of this first operation, the auxiliary clamping device 20 is opened and the workpiece 17 is released, whereupon, with the main clamping device 10 still secured, the coordinate table T is moved in the main feed direction of its X-axis to the second machining position of the workpiece 17. The auxiliary clamping device 20 is then actuated again and the next machining operation is initiated and carried out. In this way, the machining of the workpiece 17 can be carried out, until the main clamping device 10 reaches the safety region of the auxiliary clamping device 20. In order to avoid any collision and allow machining oftheworkpiec 17 to continue, both clamping devices 10 and 20 are provided with switch members, here the main clamping device 10 with a switch cam 24 and the auxiliary clamping device 20 with a switch 24'.

On approach of the main clamping device 10 to the auxiliary clamping device 20, the cam 24 actuates the switch 24' and, by correspondingly actuated controls, a further movement of the coordinate table T with the workpiece 17 is prevented. In order to be able to effect further advance in the main feed direction, namely along the X-axis, the auxiliary clamping device 20 is closed and the main clamping device 10 is opened. By then moving the coordinate table back along the X-axis counter to the main feed direction, i.e. to the left in Figure 1, the main clamping device 10 is shifted with respect to the workpiece 17, that is, the main clamping device 10 is then again located in the starting position illustrated in Figure 1.After securement of the main clamping device 10 and the opening of the auxiliary clamping device 20, further machining operations can be carried out on the workpieces 17, in the way already described above.

Theoretically, it is possible in this way to subject even endlessly long pieces to the most varied operations, particularly to carry out information of the most varied apertures. In piercing presses with tool magazines, particularly in revolving piercing presses, piercing tools with varied diameters can be employed. Moreover, it is also possible, within the scope of the possibilities given by the machine, to effect feed movements in the secondary feed direction, namely along the Y-axis, and thus to provide the workpiece 17 with any conceivable machining program. For this Y-axis movement, in the way illustrated, the two clamping devices 10 and 20 would both remain operative, i.e. closed.

Since in practice no endlessly long workpieces are required, it is necessary to sever these workpieces during the course of the sequence of steps, corresponding to the prescribed lengths. For this purpose, instead of the machining or piercing tool 21 as illustrated in the embodiment, a shearing tool can be brought into the operative position, e.g. the tool 25 in Figure 1, with which the workpieces can then be cut to their prescribed lengths.

If the workpiece to be severed is so long that its centre of gravity already lies on an inclined roller track 22 provided on the machine tool in the main feed direction (X-direction), the workpiece then rolls on to the inclined roller track under its own weight and can then be collected in a suitable collecting box (not shown). Shorter lengths of the workpiece remain in the channel 23 provided on the machine tool and are then pushed on to the roller track 22 by the following piece parts of the workpiece and then can also roll away automatically. In order to achieve a simpler introduction of the longitudinallyextending workpieces 17, as shown in Figure 1, the left-hand sheet support of the coordinate table T is provided with a non-inclined roller track 26, which is arranged beneath the main clamping device 10 and the incoming path of movement for the workpiece 17, as Figure 1 shows.

As already explained, by suitable construction of the clamping devices 10 and 20, and particularly of their gripper means 12, 15, longitudinally-extending workpieces with the most varied contours can be held fast and fed forwards.

Claims (10)

1. Apparatus for machining longitudinallyextending workpieces on a machine tool having a coordinate table for the feed movement of the workpiece, in which the coordinate table includes clamping means for the workpiece in two directions of movement, in which on that clamping means of the coordinate table movable in the main feed direction (X-axis), there is provided, on the side facing the machining tool zone, a workpiece stop pivotable out of the region of movement of the workpiece and arranged to be abutted by the forward end of the workpiece, and, on the side away from the machining tool zone, a main clamping device provided with driven gripper means adapted to the contour of the workpiece, and in which, between the workpiece stop and the main clamping device, there is provided an auxiliary clamping device likewise provided with driven gripper means adapted to the contour of the workpiece, and secured at a prescribed distance from the operatve machining tool on that part of the coordinate table movable in the second feed direction (Y-axis).

2. Apparatus according to claim 1, in which the stop comprises a support securable to the clamping means and a pivot member pivotable on the forward end of this support and carrying an abutment surface for the workpiece, the pivot member being pivotable by a drive mechanism arranged on the support.

3. Apparatus according to claim 1 or 2, in which the main and auxiliary clamping devices each comprise a base member securable on the respective clamping means and gripper means comprising a clamping member longitudinally-movable between guides on the base member by means of a drive unit, the clamping member clamping the workpiece between a clamping surface formed on it and adapted to the contour of the workpiece and associated abutment surfaces on the base member.

4. Apparatus according to claim 3, in which the abutment surfaces are formed by the forward end faces of the guides formed as fork-shaped projections of the base member, and the clamping surface is formed by a rear wall of a gripper projection provided on the clamping member.

5. Apparatus according to claim 3 or 4, in which the drive unit of the clamping member is arranged on the base member.

6. Apparatus according to any of claims 3 to 5, wherein a shim member is provided inserted against the clamping surface for reducing the gripping width of the gripper means.

7. Apparatus according to any preceding claim, in which at least one of the clamping devices carries a proximity switch member which is actuated when the clamping devices are at a predetermined distance apart.

8. Apparatus according to any preceding claim, in which, in the main feed direction, as extensions of the machining tool zone, there is provided a collecting channel and an associated inclined roller run-off track in the main feed direction for the machined workpiece.

9. Apparatus according to any preceding claim, in which a roller track for the incoming workpiece is located beneath the main clamping device in its starting position and thus beneath the input path for the workpice.

10. Apparatus for machining longitudinallyextending workpieces substantially as hereinbefore described with reference to the accompanying drawings.