DE3533001A1 - Method for fixing tools and/or workpieces on a machine tool and a fixing device for carrying out the method - Google Patents

Abstract

To fix tools and/or workpieces on a machine tool, in particular cavity-sinking electrodes and/or workpieces on an electroerosion machine, these parts are fixed by means of soft-soldering. In terms of the device, fixing mandrels (42) mounted on the sleeve and/or on the machine table have an electric heating device (36), which can be switched on and off by the machine control. The mutually facing fixing surfaces of the fixing mandrel (42) and of the unattached electrode (43), of the workpiece or of the workpiece pallet have a coating (35) of solderable material, the melting point of which is of the order of 60 DEG C to 200 DEG C. The fixing mandrels (42), the unattached electrodes (43) (tools), the workpieces and any workpiece pallets used have flushing bores (44), the flushing liquid required in the erosion process here also serving to ensure more rapid cooling of the soldered joint. <IMAGE>

Description

The invention relates to a method for clamping of tools and / or workpieces on one tool machine, in particular of lowering electrodes and / or work pieces on an electrical discharge machine and on one Clamping device for performing the method.

At the 4th EMO machine tool exhibition in 1981 in Hanover the Swedish company 3R provided automatic electrodes changer for die sinking EDM machines. It was also  shown that you have complicated sink electrodes in part break down electrodes.

Also with other machine tools such. B. lathes, Milling machines etc. have long been automatic tool changers known. The tools are made by mechanical over feeding devices fed to mechanical clamping jaws, which they grasp and clamp firmly.

In practice, however, tension occurs again and again errors caused by the clamping movement.

For example, these tensioning errors are caused by Verunreini conditions (e.g. metal chips) in the clamping area as well also by tilting the tool in the jig.

About the instep that is not always completely avoidable error in the subsequent machining of the workpiece it is also known not to let it take effect (time writing: "Technische Rundschau 29, 1985, pp. 8 to 11) die Workpieces and tools mechanically or electronically measured and then ge in a numerical control saved path data for processing according to the correct the measured clamping error. This requires however considerable programming effort. It is better undoubtedly to avoid the tension errors. Task of he It is therefore the process and the clamping device to improve the process of the type mentioned at the beginning that a highly precise, fully automatic, detachable on clamping of tools and / or workpieces on a work test machine is possible.

This task is carried out in the characterizing part of the Claims 1 and 5 specified features solved.  

Advantageous refinements and developments are the See subclaims.

Instead of mechanical clamping and thus a form and / or frictional connection in the invention the object to be clamped is soldered on. So that the ver binding is easily released again, it is done by means of Soldering.

The invention can be particularly advantageous in a Use EDM machine, starting from Raw electrodes and raw workpieces all work operations, including machining the raw electrode be carried out on a single machine without in between the use of a human being is required.

In the following the invention is based on exemplary embodiments play in more detail in connection with the drawing explained. It shows

Figure 1 shows an example of the clamping device when clamping a tubular tool.

Fig. 2 shows a similar example with a plate-shaped tool;

3 shows an example of the clamping device for clamping a workpiece supporting work pallet.

Fig. 4 shows an example of the clamping device for the direct clamping of a workpiece on the machine table;

Fig. 5 shows another embodiment of the clamping device in a specially shaped workpiece;

Figures 6 and 7 examples of tool and / or workpiece magazines for use in the invention.

Figures 8 to 10 another embodiment for the provision of tools or workpieces for use in the invention; and

Fig. 11 shows an electrical discharge machine with the clamping device according to the invention.

Identify the same reference numerals in the individual figures same or corresponding parts.

Although the invention is related to an Elektroero sion machine is described, it should be emphasized that it is also generally applicable to machine tools. The limits for the application of the invention are single Lich in the strength of the solder joint and in the Tempera occurring during the use of the workpiece structures on the tool or workpiece. As with EDM machines on the tool (electrode) and the work mechanical forces generally less are than with other machine tools, especially with cutting machine tools, is a preferred Field of application of the invention is electroerosion.

Reference is now made to FIG. 1. A mandrel 42 attached to the quill of the machine has at its lower, free end a coating 35 made of metal or a corresponding metal alloy melting at low temperature (approx. Between 60 and 200 ° C.). In the area of the lower end of the mandrel 42 a winding development of an electrical resistance heater 36 is attached, which can be connected to a power supply via controllable switches. In an electroerosion machine, the resistance heater 36 is preferably connected to the erosion generator.

The tool, here a raw electrode 43, is now to be clamped onto this mandrel. In the example in FIG. 1, this raw electrode has a cylindrical shape. At its upper end, which faces the mandrel 42 , it also carries a coating 35 made of a suitable solderable material. The mandrel and the raw electrode have flush bores 44 aligned with one another for the subsequent erosion process. In addition, a coolant can also be passed through this flushing bore 44 for faster cooling of the solder joint. To clamp the raw electrode, the mandrel is aligned above the raw electrode by relative displacement between the quill and a raw electrode magazine and contact is made by moving the Z axis of the quill. Then the resistance heater 36 is switched on, so that the coatings 35 heat up above their melting point and thus the raw electrode 43 is soldered to the mandrel.

In Fig. 2, the raw electrode 43 has a plate shape with two oblique flushing holes, which are in flow connection with the flushing hole of the mandrel 42 . An induction coil 37 is provided here as an electrical heating device, which is fed with high-frequency pulses - possibly also from the erosion generator. The top of the plate-shaped raw electrode 44 also has the coating 35 .

It can be seen from the examples in FIGS. 1 and 3 that practically any electrode or tool shape can be clamped, provided that there are correspondingly adapted clamping surfaces on the mandrel and the tool.

Fig. 3 shows an embodiment for the clamping of a workpiece by means of a tool pallet on the machine table. A tool pallet 30 of a known type has a plurality of projections pointing downwards, which in turn are provided with the coating 35 . The workpiece 31 is fixed on the workpiece pallet 30 in a known manner. Here too, flushing bores 44 are provided through the workpiece 31 and the workpiece pallet 30 , which end in one of the projections and thus also pass through the coating 35 . Corresponding clamping pins with heating devices are provided on the tool table, so that the workpiece pallet can also be soldered to the tool table in an analogous manner at the factory. A bell-shaped mandrel 61 with a pin projecting vertically upwards is provided for the transport from a workpiece magazine to the clamping point on the tool table. This pin can also have a coating 35 . This pin is soldered according to the embodiment example of FIGS. 1 and 2 on a mandrel of the quill and then moved by relative displacement between the quill and machine table to the clamping point on the machine table. Then the resistance heating of the table-side mandrels is switched on, so that the workpiece pallet 30 is soldered to the table. The clamping mandrel 61 has at its ends facing the workpiece pallet 30 at least one permanent magnet 34 which rests on a corresponding clamping surface 33 of the workpiece pallet. The magnetic forces are sufficiently strong so that the mandrel 31 can carry the workpiece pallet 30 with the workpiece 31 . As soon as the workpiece pallet 35 is soldered to the machine table, the holding force of the soldered connection is stronger than that of the electromagnet (s) 34 , so that the mandrel 61 can be lifted by shifting the Z axis of the quill.

The mandrel 61 can then be stored in an automatic tool or workpiece changer, the quill side solder connection being released by heating.

FIG. 4 shows a further exemplary embodiment in which the workpiece 31 is soldered onto the machine table 1 directly, ie without a workpiece pallet. In the exemplary embodiment in FIG. 4, it is a gearwheel that carries the coating 35 on both sides (top and bottom). The machine table 1 has a plurality of mandrels 32 , each having a heater 36 . The table-side mandrels 32 are also provided with the coating 35 . The table-side mandrels 32 are welded to the table 1 . According to the above exemplary embodiment, the workpiece is removed from a workpiece magazine by the mandrel-side mandrel by soldering the workpiece 31 to the mandrel-side mandrel. Then, the workpiece 31 transported advantage to the table side mandrel 32 and soldered by heating the same with its underside on the mandrels 32nd The soldered connection on the pinole side is then loosened again by heating.

Fig. 5 shows a further embodiment of the invention, in which the mandrel-side mandrel 42 carries a permanent magnet 34 and a downwardly projecting into an opening of the workpiece 31 centering nose. The underside of the bell-shaped workpiece 31 here in turn carries the coating 35 . The workpiece 31 is picked up from a workpiece magazine and transported to the table-side mandrel 32 by the force of the magnet 34, while the actual clamping of the workpiece 31 on the table-side mandrel 32 is in turn carried out by soldering.

It can be seen from the examples in FIGS. 1 to 5 that no clamping error can occur due to a clamping movement of clamping jaws. If the position of the electrical electrode 43 or of the workpiece (possibly the workpiece pallet) is known exactly, the quill can also approach it exactly. Due to the very precisely controllable movement of the machine, this position and the later position of the table-side mandrels can be approached precisely. During soldering, the parts to be connected are to be held tight, and after the solder joint has cooled, no more displacements can occur. The entire clamping process can also be carried out fully automatically without human supervision, so that fully automatic 24-hour operation is possible.

FIGS. 6 and 7 show two embodiments of tool or workpiece magazines 53rd In the concrete from routing case, FIG. 6 is a vertical stacking magazine with stacked Rohelektroden 43 each having on its upper side, the coating 35th These raw electrodes 43 also each have a rinsing hole 44 . The raw electrodes 43 are pressed by spring force F upward against a transfer device 52 , which are formed here by inwardly projecting, part of the raw electrodes 43 covering tabs. Below these tabs, the stack magazine 53 has an opening corresponding to the width of the raw electrode 43 . When removed, the coating 35 is fused to the coating of the mandrel 42 and then removed by moving it in the Y -axis direction to the front or back. After removal, the next raw electrode 43 jumps into the removal position.

In Fig. 7 a horizontal stacking magazine 52 is shown, which functions in the same way. Here only tubular electrodes 43 are removed upwards.

Figs. 8 to 10 show a different kind of magazining Rohelektroden 43rd The raw electrodes are brought into band form by punching or milling in corresponding automatic machines, leaving a connecting web 45 , so that it is possible to wind up to several thousand raw electrodes 43 on a coil magazine ( 50 in FIG. 11). When the raw electrode 43 is removed, this web 45 is removed by a punching or shearing device. These raw electrodes also have the coating 35 on the tension side and can also have prefabricated rinsing bores.

Fig. 11 shows an erosion machine in which the Spannvor direction according to the invention is used. This machine has in addition to the components not shown: numerical control, generator and Dielektrikumsauf preparation, a table 1 , a dielectric container 7 with the first work space 2 and second work space 3 , a quill 4 , a raw electrode magazine 5 and an electrode denchanger 6 .

The table 1 has drives for the X axis 10 , for the Y axis 11 and for a rotation axis 12 for a wire cutting device 20 which is rotatably attached to a side wall of the container 7 Be. The first work area is intended for wire cutting EDM. In it - as mentioned - the wire cutting device with a wire electrode 21 is rotatably supported via an axis of rotation A. The usual elements of a wire cutting machine such as unwinding reel, wire drive, power supply, wire guides, rinsing nozzles and winding reels are used. The function of these elements is basically the same as that of a known wire cutting machine. Advantageously, however, the notches of the wire guide are made less deep than the wire electrode diameter in order to realize as many degrees of freedom as possible for the wire cutting processing. The wire cutting device 20 is constructed, for example, from a bracket 25 which has two arms 26 and 27 running parallel to the main working plane (XY plane) of the machine. The wire electrode 21 is stretched between the free ends of these arms 26 and 27 . On these arms, a bit set back from the wire electrode axis, a drilling device 22 and a probe 23 can be attached. The drilling device 22 may be an assembly as is commonly used on wire cutters. However, it can also be much simpler in that a pin-shaped or tubular raw electrode 43 is clamped onto the drilling device 22 in the same way as described above. The drilling device 22 does not need its own feed drive, since the feed movement can also be carried out by the five machine axes (X, Y, Z, C, A) already present. The first working space is provided for processing raw electrodes 43 , which form the workpiece during this process, but the tool during a subsequent machining of the workpiece 31 .

The bracket 25 is still designed so that the arms 26 are offset from the axis of rotation A or the axis of the drive 12 .

The second work space 3 is provided for the execution of the Senkpro process and is normally flooded with a carbon hydrogen dielectric. For special applications with small electrodes, however, it can also be advantageous to drive the lowering process with an aqueous dielectric, corresponding to the dielectric during the cutting process in the first work space 2 . In this case, a partition wall 24 between the first and the second work space 2 and 3 could be omitted. In the second work space 3 , several table-side mandrels 32 are provided, of which only 3 are shown in FIG. 11. These mandrels 32 are used to clamp the workpiece pallets 30 or directly to clamp specially prepared workpieces 31 .

The sleeve 4 can be moved via a Z axis drive 40 and additionally has a rotation axis C , which can rotate the mandrel 42 with the electrode 43 via a drive 41 . Slip rings and rinsing bushings are provided, which do not limit the angle of rotation. Several raw electrode magazines 5 are arranged, for example, behind the first working space 2 . There, raw electrode strips 51 (corresponding to FIGS . 8 to 10) are wound on coils 50 or stack magazines 53 (corresponding to FIGS. 6 and 7) are present in which the individual electrodes 43 are stored. Transfer devices 52 ensure a flawless removal of the raw electrodes from the magazine. Small rough workpieces such as nozzles, micro parts and cutting inserts for cutting tools can also be stored in magazines of the same type.

In addition to the second working space 3 , the electrode changer 6 is arranged, which is also moved relative to the sleeve 4 by the existing machine axes, X, Y, Z. There are 42 workpiece pallets 61 , probe 64 , finished special electrodes 63 , empty mandrels 60 and used but still usable electrodes 62 stored by means of standardized mandrels 42 .

A typical machining cycle is as follows:

• 1. A workpiece pallet 61 loaded with the workpiece 31 is removed from the electrode changer 6 and clamped onto the sleeve 4 in a conventional manner.
• 2. The first work area 2 is approached and a possible clamping error is measured with the measuring probe 23 (axis A) rotated into a favorable position.
• 3. The second work area 3 is approached. The pallet 61 is aligned via the axes X, Y, Z, C so that the clamping error becomes zero.
• 4. The pallet 61 is connected to the table-side mandrels 32 according to the invention; The mandrel-side mandrel 42 is detached from the pallet 61 and temporarily stored in the electrical denchanger 6 .
• 5. A suitable, empty mandrel is removed from the electrode changer 6 and charged with a suitable raw electrode 43 according to the invention in the raw electrode magazine 5 .
• 6. The raw electrode is machined to final dimensions with the wire cutting device 20 .
• 7. In the second working space 3 , the desired shape of the workpiece is generated by translation and / or rotation via the X, Y, Z, C axes.
• 8. Repeat steps 5 to 7 if necessary. Worn electrodes 43 are each thrown into a waste container. Mandrels 60 that are no longer used are again stored in the electrode changer 6 .
• 9. In the reverse sequence, the pallet 61 with the finished workpiece 31 is brought back into the electrical denchanger 6 .
• 10. A new, possibly different, working cycle will started automatically.

This example clearly shows that in addition to the Provision of suitable raw material, creation the machining program and removal of the finished one Workpieces do not involve human operations fall. Many cycles can only be done once providing, so-called utility even automatically to be generated. Such utilities include Tables with empirical values, calculation algorithms for parameters and tables with coordinate values of Electrode changer, clamping position, measuring position and the like. The creation of these utilities is very expensive but worthwhile, since afterwards everyone System users benefit.

The processing example shown in connection with FIG. 11 also shows the importance of the clamping method and the clamping device according to the invention. With traditional clamping systems, such a processing sequence can only be solved very poorly, since the material to be chucked can vary in weight from a few grams to a few tens of kilograms. The clamping operation must also be carried out extremely precisely in the approached position and must not be subject to any deviation due to clamping movements.

In brief, the clamping method according to the invention is based on a fusion process between two coatings 35 made of a soft solder alloy, which are applied to a heatable mandrel and the material to be clamped. The coating thickness enables correction values up to a few µm in all spatial axes. As is known from electrical engineering, the soft solder alloy naturally also contains so-called flux, which ensures that the surfaces to be connected are properly wetted with the solder during the soldering process. Soft solders used in the electrical industry and soft solder pastes applied by screen printing technology can certainly meet the requirements set here. The melting of the solder takes only a few seconds when the heating devices are connected to the erosion generator. The cooling time can be greatly reduced by the flushing liquid in the flushing bores 44 .

All in the godfather sayings, the description and the technical details shown in the drawing can be used both individually and in any combination be essential to the invention with each other.

Claims (18)

1. A method for releasable clamping of tools and / or workpieces on a machine tool, in particular special sink electrodes and / or workpieces on an electrical discharge machine, characterized in that the tool and / or the workpiece are clamped by means of soldering. 2. The method according to claim 1, characterized in that the tool and / or the workpiece by heating be solved again. 3. The method according to claim 1, characterized in that when clamping the heated solder joint by a flowing liquids or a flowing gas cooled becomes. 4. The method according to one or more of the claims 1 to 3, characterized by the use of a Metal or an alloy with a melting point between 60 ° and 200 ° C. 5. Clamping device for releasably clamping work and / or workpieces on a machine tool, in particular for releasably clamping lowering electrodes and / or workpieces on an electroerosion machine, in particular for carrying out the method according to one or more of claims 1 to 4, characterized in that a tool holder (e.g. sleeve 4 ) of the machine and / or the machine table ( 1 ) have at least one firmly fixed mandrel ( 42, 32 ) that each mandrel ( 42, 32 ) is assigned a controllable electrical heating device ( 36, 37 ) and that the free end of the mandrel (s) ( 42, 32 ) and / or an opposite surface of the tool ( 43 ) and / or the workpiece ( 31 ) in the clamping state is a coating ( 35 ) from a low melt metal or a low-melting alloy (soft solder alloy). 6. Clamping device according to claim 5, characterized in that the melting temperature of the metal or the soft solder alloy ( 35 ) is between 60 ° and 200 ° C. 7. Clamping device according to claim 5 or 6, characterized in that the mandrel or mandrel (s) ( 42, 32 ) and the tool ( 43 ) or the workpiece ( 31 ) each have the coating ( 35 ). 8. Clamping device according to claim 7, characterized in that the coating ( 35 ) on the tool ( 43 ) or on the workpiece ( 31 ) additionally contains a flux. 9. Clamping device according to one or more of claims 5 to 8, characterized in that the Heizein direction is an electrical resistance heater ( 36 ). 10. Clamping device according to one or more of claims 5 to 8, characterized in that the Heizeinrich device is an electric induction heater ( 37 ). 11. Clamping device according to claim 9 or 10, characterized in that the heating device ( 36, 37 ) in an electroerosion machine is connected to its erosion generator so that it can be controlled or switched. 12. Clamping device according to one or more of claims 5 to 11, characterized in that the mandrels ( 32, 42 ), the tools ( 43 ) and the work pieces ( 31 ) and, if necessary, and workpiece pallets ( 30 ) rinsing holes ( 44 ). 13. Clamping device according to one or more of claims 5 to 12, characterized in that the workpieces (31) are mounted on the workpiece pallet (30) and that the workpiece pallet (30) gegenüberlie quietly on the table side mandrels (32) processing the Beschich ( 35 ). 14. Clamping device according to claim 12 and 13, characterized in that the rinsing hole ( 44 ) through the loading coating ( 35 ) of the workpiece pallet ( 30 ) passes. 15. Clamping device according to claims 13 or 14, characterized in that a mandrel ( 61 ) for holding the workpiece pallet ( 30 ) during transport on its side facing the workpiece pallet ( 30 ) has at least one permanent magnet ( 34 ). 16. Clamping device according to one or more of claims 5 to 12, characterized in that in an electroerosion machine the mandrel-side mandrel ( 42 ) has a permanent magnet ( 34 ) for holding the workpiece ( 31 ) during its transport. 17. Clamping device according to one or more of claims 5 to 16, characterized in that the workpieces ( 31 ) are arranged in a magazine ( 50, 53 ) which can be approached by the sleeve of the machine. 18. Clamping device according to one or more of claims 1 to 17, characterized in that tools, workpieces on workpiece pallets and, if necessary, measuring probes are arranged in a tool changer ( 6 ) that can be approached by the sleeve of the machine.