DE3923261A1 - Wire feed arrangement for wire erosion machine - has controlled position direction changing roller compensating wire tension variations - Google Patents

Abstract

The wire feed arrangement has a motor (2) driven wire supply spool mounting for a spool (24) from which wire (13) is taken off to a workpiece. The wire passes over a variable position direction changing device between two fixed positions which compensates for wire tension variations. The direction changing device's (34) position is detected by a sensor (4) which feeds a control unit controlling the spool drive according to the sensor signal. ADVANTAGE - Ensures reliable, problem-free drawing of wire electrode of wire erosion machine from its supply spool.

Description

The present invention relates to a wire feeder Direction for a wire EDM machine with a wire Supply spool holder, to which a wire supply spool can be attached and from which the wire electrode or the wire is removed and fed to the workpiece can.

Required to operate a wire EDM machine Lichen wire electrodes are in the form of wire stocks coils offered to the user. The wire supply spool is attached to the wire EDM machine, in which Usually unwinding the wire electrode from the coil alone by pulling the wire as a result of the wire drive eroding machine. This has certain disadvantages with itself, in particular there is a risk of tearing the wire electrode especially when heavy wire is in front Council reels are used in which the unwinding of the Wire electrode one compared to small coils high strength required. This force exceeds the train strength of the wire electrode, this inevitably leads  to break the wire electrode. Besides that, it leads alone pulling off the wire via the wire drive electrode from the supply spool may also to the fact that - this is especially the case with small light ones Coils to be feared - the supply spool overturned and it leads to sagging of the stripped wire elec trode can come, which in turn ver ver can result in various types.

An object of the present invention is now a generic wire feeder for a Wire EDM machine to create a safe, easy removal of the wire electrode from one Wire supply spool guaranteed.

This goal is achieved by a generic wire guide device, which is characterized by a drive to ensure the unwinding of the the wire supply spool, one with a deflector equipped in their position changeable compensation device for deflecting the between two fixed points of predetermined wire course and thereby to compensate for the unwinding process occurring wire voltage change, with a sensor system Scanning the respective position of the compensation direction, and a control unit for control the drive of the wire supply spool using the Sensor signals.

The compensation device acts as it were Wire electrode tensioner. By the interaction of the Drive with the compensation device can continuous feeding of the wire electrode under Ver Avoidance of wire electrode tear or otherwise Disruptions occur. Increased reliability of the  Wire feeding is particularly important because of wire EDM machines are often exposed to 24-hour operation are. To carry out the wire feeder required mechanics can be due to the innovation particularly simple and uncomplicated, which makes the Innovation proves to be very reliable, designed be. Due to the use of an autonomous drive becomes a variable wire speed at the same allows permanent wire tension. The wire tension can by changing the deflection of the compensation required force set arbitrarily will.

As a compensation device is preferably a linear slidably arranged, the deflection device taking carrier provided. This carrier can be in one multiple ways as a crosshead along two Guides can be arranged.

For setting the force used to deflect the wire i.e. the carrier stands for adjusting the wire tension with a weight in connection with the own counteracts the weight of the deflection device. This ent Counteraction can be caused, for example, by several deflections roles can be achieved.

A configuration of the The present invention is characterized in that as a compensation device one around a pivot point pivoted out with the deflection Equipped compensating arm is provided. This Ausge Mechanical design is particularly simple and un complicated to realize.  

The fact that according to a further embodiment of the wire feeder of the compensation according to the invention arm has a weight, which along the Aus is arranged equally displaceable, can by the compensating arm on the unwound wire electrode applied pressure can also be varied. Example wise the pressure can be reduced with thin wire electrodes be reduced speaking. The combination of the pivoting balance arm with the move Lich arranged weight offers a very constructive elegant solution.

Another useful embodiment of the Invention According to the feeding device, that in the area of the deflector on the compensating arm or fine weights can be applied to the carrier. This ensures that in addition to the actual Lichen, already mentioned weight, which for Rough adjustment can serve to fine tune the force acting on the wire electrode can be achieved.

Because the drive has a drive motor, which with the wire supply spool via a coupling member is connected, it is advantageously ensured that differed due to the use of the coupling member Liche engines can be used, the An adjustment of the drive speed (or a lower or gear ratio) by the coupling member can be done.

A toothed belt can expediently be used as the coupling member or a chain can be provided.

Another useful embodiment of the Invention It is characterized by the wire feeding device  records that the wire supply spool holder a so Detachably connected adapter piece. This will Allows wire spools to be different Size, different length etc. in a simple way can be attached to the wire feeder.

For particularly heavy wire supply spools (for example with a 45 kg spool available in specialist shops) the adapter piece expediently on a counter bearing.

To the friction or rolling forces caused by the deflection direction of the compensating arm on the wire electrode practiced to keep it as low as possible is the order Steering device expediently as rotatably mounted Role trained.

According to a further expedient embodiment of the wire feeder according to the invention is in Be range of movement of the compensation device, i.e. in the Swivel range of the compensating arm at least one on beat to limit the swivel range or loading movement range provided. This feature causes - it should become one due to some circumstance Wire break come - the swivel range is limited to to avoid damaging other components.

The control unit is advantageously such a directed that the drive is either pulsed controllable is or is regulated continuously. Pulsed Control means that the wire supply spool is dependent speed of the sensor signals only after a certain time interval vallen is driven. A continuous settlement of the drive means that wire depending on the guided wire tension continuously from the Wire supply spool is delivered. That way  due to the effect of the compensation device a con Remove the wire electrode from the wire feeding device with constant wire tension respectively.

A special development especially for the ge pulsed drive is that the unit is a Drive control includes which the speed of the An drive continuously increases when the drive is active. As a result, a "soft" start of the Drive guaranteed and the risk of wire break further decreased.

As far as the control of the drive is concerned, a white one tere advantageous embodiment for the pulsed This drives the wire feeder characterized that the sensor technology photoelectric sensors has whose photo stream by pivoting the Compensating arm or linear movement of the carrier is interruptible and are connected such that when another light barrier is actuated, the drive started when the second light barrier is actuated is stopped. This can be done in a simple manner the control of the drive depending on the position the compensation device.

The drive control can also be activated done by a light barrier.

In addition, a light barrier can be provided by means of which the drive can be switched off in the event of a wire break is.

According to a further embodiment of the invention Wire feeder is the sensor technology or are Photoelectric sensors on a largely transverse to the axis of the  equal or transverse to the axis of the carrier Fastening device slidable, however in the Position fixable. By simply moving it the light barriers can therefore control characteristic can be influenced.

Another useful embodiment of the present Innovation is characterized in that instead of Photoelectric sensors the sensors in the pivot point of the Compensating arms arranged or the linear movement of the carrier scanning angle encoder or Glass scale. This allows the angle position of the compensating arm or the position of the Detect the carrier and control the drive basic. If the encoder is in addition to Used light barriers, this has the advantage that in In the event of failure of the photoelectric sensors of the encoder so to speak, an "auxiliary sensor system", which then guarantee the continued operation of the drive control accomplishes.

The sensor system can expediently be used to determine the Position of the compensation device, i.e. the spin position of the balance arm or the position of the As an alternative to an encoder, a photo have sensor with analog output. The photo sensor with Analog output has the advantage that it does this Analog signal obtained directly for continuous Control of the drive can be used. It is not necessary here, a pulsed control of the Drive.

Another useful embodiment of the Invention the appropriate wire feeder is characterized net that a wire tension sensor and / or a wire speed  digkeitssensor is provided. This will make the poss created the wire pull and / or the Signal representing wire pulling speed decrease and the basis of the control of the drive lay. In particular, it is possible to use these signals as Include target values in the control.

Advantageously, the wire conveyor is intended speed a sensor on the wire drive the wire eroding machine arranged. Here, too, can be viewed as Sensor an encoder or a photo sensor with Ana Use the log output appropriately.

Furthermore, the control unit can run a free program mable calculator. This can influence sizes or parameters adapted to all influences will.

Another useful embodiment of the Invention the appropriate wire feeder is characterized records that at the output of the wire feeder adjustable in height and / or in terms of rolling Directional deflecting device, preferably Deflection roller is provided. This will be advantageous guarantees that the wire feeder direction in any way next to a wire EDM machine can be arranged. The setting both the feed height and the feed direction of the wire can by adjusting the deflection are optimally guaranteed.

The present innovation still concerns a wire EDM machine with one on a machine frame arranged workpiece holder, one through the workpiece holder guided wire electrode by a wire  supply spool is withdrawn via guides to the factory piece holder and led away from this as well as a Sam Mel container is supplied, the wire EDM machine is characterized by a wire feeder according to at least one of the protection claims 1-25.

The following is only a practical Ausgestal device of the wire feeder according to the invention Reference to the Fi shown in the drawing guren explained in more detail. Show it:

Figure 1 is a highly schematic representation of the mechanical structure of the wire feeder according to the innovation.

FIG. 2 shows the wire supply coil holder of the wire feed device according to FIG. 1 in section; and

Fig. 3 is a block diagram showing the sensor technology and the features of the control technology of the wire feeder according to the invention.

Reference numeral 1 in Fig. 1 denotes the wire feed device in its entirety. The wire feeder 1 comprises a wire supply spool holder 22 , to which a wire supply spool 24 can be fastened by means of an adapter piece 23 described in more detail below. The wire supply spool holder 22 is connected to a drive 2 , which comprises a motor 21 , which is non-positively connected by means of a toothed belt 25 with the rotatably mounted wire supply spool holder 22 . An electric motor can advantageously be used as the motor.

From the wire supply coil 24 , the wire or the wire electrode 13 is withdrawn via a support roller 5 and further guide rollers 6 , 7 and 8 in the direction of the wire EDM machine (DEV), ie in the direction of the workpiece. The wire is pulled off by the wire drive of the wire EDM machine of a type as described, for example, in DE-PS 36 31 888.

To ensure the maintenance of a certain wire tension, a compensating device in the form of a compensating arm, generally identified by reference number 3 , is provided. The compensating arm 3 has a rod 31 which is pivotally connected to a frame (not shown) by means of a swivel joint 32 . At one free end of the rod 31 , a deflection device in the form of a deflection roller 34 is provided, which is freely rotatably mounted on the rod 31 .

At the free end of the rod 31 opposite the deflection roller 34 , a weight 33 is arranged, which can be moved along the rod 31 . By moving this weight 33 , the roll exerted by the deflection 34 on the wire 13 can vary the who.

In addition, the deflection roller 34 has a holder 35 , which serves to accommodate fine weights. This Hal can be formed for example in the form of a perpendicular to the plane of the retaining strip 36 . By pushing on (not shown) fine weights on these retaining strips, the pressure exerted by the compensating arm 3 on the wire 13 or the wire tension caused thereby can be adjusted very precisely.

The compensating arm 3 thus causes by its Eigenge weight or by additionally applied weights a deflection of the between the support roller 5 and the Füh approximately roller 6 extending wire 13th

When the wire supply spool 24 is fixed, pulling off the wire 13 through the (not shown) wire drive of the wire EDM machine has the consequence that the end of the compensating arm 3 assigned to the deflection roller 34 is gradually pulled upwards. In order to avoid a wire break, the drive 2 is therefore actuated in dependence on the pivoting position of the compensating arm 3 in such a way that a certain length of wire is unwound over a certain period of time.

The sensor system 4 for determining the respective pivot position of the compensating arm 3 is described below. The sensor system 4 comprises four light barriers 41 to 44 , which are arranged on a fastening device 45 . The fastening device 45 can be, for example, a rod, bar or the like. The arrangement is such that the photocurrent of each light barrier can be interrupted by pivoting the compensating arm. The fastening device or the individual light barriers are preferably arranged largely perpendicular to the pivoting direction of the compensating arm 3 .

From Fig. 3 it can be seen how the individual light barriers 41 to 44 are connected, it being pointed out that this representation represents only a few of many circuit options. The connection and acts directly on the drive 2 , such that the drive 2 is switched on when the light barrier 42 is interrupted. Of course, the light barrier 42 can also be connected directly to the supply to the drive.

The light barrier 41 is also connected to the control unit 9 , also acts directly on the drive 2 , but here in such a way that when the light barrier 41 is interrupted, the drive 2 is switched off fully.

Furthermore, the light barrier 43 ensures the acti vation of the drive control, which ensures a smooth operation of the drive.

Finally, the light barrier 44 has the function of switching off the drive 2 in the event that a tape break occurs, but the drive 2 would still be active. The light barrier 44 consequently has only a hedging function.

Instead of this discontinuous control, which takes place by means of light barriers, a photo sensor with an analog output, which is preferably arranged in the pivot point 32 of the compensating arm 3 , can be used, the signals of which can be used for the direct continuous control of the drive 2 . In this configuration, there is no "swinging" of the compensating arm, the compensating arm 3 is rather relatively quiet.

In addition to or instead of the light barriers 41 to 44 , a so-called angle encoder 46 can also be used to code the respective rotational position of the compensating arm 3 and thus to control the drive 2 . This also allows a contactless control of the wire tension to ensure in an advantageous manner.

In order to avoid falling of the compensating arm 3 on the wire supply spool 24 in the event of a band tear, a stop 47 is provided to limit the pivoting range of the compensating arm 3 .

The control unit directly or indirectly connected to the sensor system 4 further comprises a computer 14 for performing data processing (storage, introduction of parameters, changing parameters).

To take into account the wire tension or the wire speed, a wire tension sensor 12 or a wire speed sensor can be provided. The wire speed sensor is preferably arranged on the wire drive of the wire EDM machine. The relevant signals can then be supplied to the control unit 9 and included in the control of the drive.

At the output of the wire feeding device 1 is a deflecting device 48 is provided, which has a deflection or or guide roller 8, which is pivotable about an axis perpendicular to the rotational axis of the deflecting roller 8 axis whereby the rolling direction of the Drahtzu transfer means leaving the wire 13 is adjustable. In addition, the transverse part 49 carrying the deflection roller 8 is arranged to be displaceable but fixable along two brackets 50 , 51 arranged in parallel. In this way, on the one hand, the height, on the other hand, the direction of the wire to be unrolled can be set.

In the following, the functional principle of the wire feed device 1 according to the innovation with a pulsed drive is explained in more detail with reference to FIG. 1. If the drive 2 is in a passive state, ie if no wire 13 is unwound, the continuously running wire drive of the wire EDM machine (wire speed v) causes the compensating arm 3 to gradually move upwards at its end facing the deflection roller 34 .

Interrupts the rod 31 of the compensating arm 3, the photo current of the photocell 43 , this causes the drive control 10 to be activated (see also FIG. 3). If the compensating arm 3 continues to move upwards, the photocurrent of the light barrier 42 is interrupted, with the result that the drive 2 is activated and, due to the activated drive control 10, it will gradually move up.

When the compensating arm 3 finally reaches the light barrier 41 and interrupts its photocurrent, this leads to the drive 2 being switched off . Due to the interim Lich unwinding of the wire 13 during the active drive 2 , the wire voltage is at least between the wire supply spool 24 and support roller 5 very low or canceled, which has the consequence that the compensating arm 3 with its deflection roller 34 facing free end moves down and thereby compensates for the change in wire tension between wire supply spool 24 and support roller 5 . The wire tension between the deflecting roller 34 and guide roller 6 or the wire tension at the output of the guide roller 8 can be kept constant due to the effect of the compensating arm 3 .

Due to the continuous wire take-off due to the operation of the wire EDM, the compensating arm 3 then gradually moves up again and the process described above is then repeated accordingly.

The compensating arm 3 consequently performs a type of pendulum movement, which ensures that wire voltage changes occurring between the wire supply spool 24 and the support roller 5 are largely compensated for.

In the case of particularly heavy rolls, it can necessary with prevailing high flywheel mass brake the drive additionally. One of the like braking can be electromechanical (for example through a coil-actuated friction lining), electronically (e.g. by reversing the field) or electro magnetic (e.g. by eddy current formation) respectively.

Another important feature of the wire feeder according to the invention relates to the wire supply bobbin holder 22 .

Since different sizes of wire supply spools are available on the market, an adapter piece 23 is expediently provided, which has an extension 27 , at the end of which a thread 28 is arranged. The extension 27 preferably has the shape of a shaft, so that it is ensured that the extension 27 can be inserted into a corresponding recess in the wire supply spool. The wire supply spool is secured by a fastening nut 29 screwed onto the free end of the extension 27 . The adapter piece 23 carrying the wire supply coil is detachably connected to the wire supply coil holder 22 . The adapter piece 23 ensures the "plugging" of various wire supply spools, all of which have a bore, through which the extension 27 passes and by means of the fastening nut a secure fit of the wire supply spool 24 on the adapter piece 23 can be achieved. The adapter piece according to the present innovation ensures the use of differently designed wire supply spools of different sizes and different bores.

All in all, the invention turns out Wire feeder as very helpful for the Operation of wire EDM machines, in particular can with possibility of adjusting the wire tension - the Danger of malfunctions in the wire feed area considerably be reduced. In addition, the wire feeder according to the invention with each any wire EDM machine can be combined. After all, the mechanical and control technology Effort relatively low. All in all, the a new wire feeder according to the innovation Enrichment of wire EDM technology.

Reference symbol list

1 wire feeder
2 drive
3 compensation arm
4 sensors
5 support roller
6 leadership role
7 leadership role
8 leadership role
9 control unit
10 drive control
11 sensor
12 wire tension sensor
13 wire
14 computers
21 engine
22 wire supply spool holder
23 adapter piece
24 wire supply spool
25 timing belts
27 extension
28 threads
29 fastening nut
31 rod
32 pivot point
33 weight
34 pulley
35 weight holder
36 retaining bar
41 light barrier
42 light barrier
43 light barrier
44 light barrier
45 fastening device
46 encoders
47 stop
48 deflection device
49 cross section
50 bracket
51 bracket

Claims (26)

1.Wire feed device for a wire EDM machine with a wire supply spool holder to which a wire supply spool can be attached and from which wire can be drawn off and fed to the workpiece, characterized by a drive ( 2 ) for ensuring the unwinding of the wire ( 13 ) wound on the wire supply spool ( 24 ) ), a deflection device equipped with a deflection device, which can be changed in its position, for deflecting the wire path specified between two fixed points and thereby compensating for the change in wire tension occurring during the unwinding process, with a sensor system ( 4 ) for sensing the respective position of the compensation device ( 3 ), and a control unit ( 9 ) for controlling the drive ( 2 ) of the wire supply spool ( 24 ) using the sensor signals. 2. wire feeder according to claim 1, characterized, that a linear shift as a compensating device bar arranged, the deflection device taking carrier is provided.   3. wire feeder according to claim 1 or 2, characterized, that the carrier is connected to a weight stands, which is the dead weight of the deflection counteracts direction. 4. Wire feed device according to claim 1, characterized in that a compensating arm ( 3 ) is seen as a compensating device a pivotally mounted about a pivot point ( 32 ), with the Umlenkein direction ( 34 ) equipped. 5. Wire feed device according to claim 1 or 4, characterized in that the compensating arm ( 3 ) has a weight ( 33 ) which is arranged displaceably along the compensating arm ( 3 ). 6. Feed device according to claims 1-5, characterized in that fine weights can be applied to the compensating arm ( 3 ) or to the carrier in each case in the region of the deflection device ( 34 ). 7. Wire feed device according to claims 1-6, characterized in that the drive ( 2 ) has a drive motor ( 21 ) which is connected to the wire supply coil ( 24 ) via a coupling member. 8. Wire feed device according to claim 7, characterized in that a toothed belt ( 25 ) or a chain is provided as the coupling member. 9. Wire feed device according to claims 1-8, characterized in that the wire supply spool holder ( 22 ) has a detachably connected adapter piece ( 23 ). 10. Wire feed device according to claim 9, characterized in that the adapter piece ( 23 ) has a counter bearing. 11. Wire feed device according to claims 1-10, characterized in that the deflection device is designed as a rotatably mounted roller ( 34 ). 12. Wire feed device according to claims 1-11, characterized in that in the pivoting range of the compensating arm ( 3 ) or in the range of motion of the carrier at least one impact ( 47 ) is provided to limit the pivoting range or range of motion. 13. Wire feed device according to claims 1-9, characterized in that the control unit ( 9 ) is set up in such a way that the drive ( 2 ) is either pulsed controllable or is continuously regulated. 14. Wire feed device according to claim 13, characterized in that the control unit ( 9 ) comprises a drive control ( 10 ) which continuously increases the speed of the drive when the drive is active ( 2 ). 15. Wire feed device according to claims 1-14, characterized in that the sensor system ( 4 ) has light barriers ( 41 , 42 ) whose photo current can be interrupted by pivoting movement of the compensating arm ( 3 ) or linear movement of the carrier and are switched in such a way, that when one light barrier ( 42 ) is actuated, the drive ( 2 ) is started, and when another light barrier ( 41 ) is actuated, the drive ( 2 ) is stopped. 16. Wire feed device according to claims 1-15, characterized in that the sensor system ( 4 ) holds a light barrier ( 43 ) ent, by means of which the drive control ( 10 ) can be activated. 17. Wire feed device according to claims 1-16, characterized in that the sensor system ( 4 ) holds a light barrier ( 44 ), by means of which the drive ( 2 ) can be switched off in the event of a wire break. 18. Wire feed device according to claims 1-17, characterized in that the sensor system ( 4 ) or the light barriers along a largely transverse to the axis of the compensating arm ( 3 ) or transversely to the axis of the carrier fastening device ( 45 ) displaceable, but in the location are arranged fixable. 19. Wire feeder according to claims 15-18, characterized in that instead of or in addition to the light, the sensor system arranged in the region of the pivot point ( 32 ) of the compensating arm ( 3 ) or a linear encoder scanning the encoder ( 46 ) or glass scale. 20. Wire feeder according to claims 15-18, characterized in that instead of or in addition to the light barriers, the sensor system ( 4 ) for determining the position of the compensating device dd, the rotational position of the compensating arm ( 3 ) or the position of the carrier, a photo sensor with analog output. 21. Wire feed device according to claims 1-20, characterized in that a wire tension sensor ( 12 ) and / or a wire speed sensor is provided. 22. Wire feed device according to claims 1-21, characterized in that a sensor ( 11 ) is arranged on the wire drive of the wire eroding machine. 23. Wire feed device according to claim 22, characterized in that an angle encoder or a photo sensor with analog output is provided as the sensor ( 11 ). 24. Wire feed device according to claims 1-20, characterized in that the control unit ( 9 ) has a freely programmable computer ( 14 ). 25. Wire feed device according to claims 1-24, characterized in that at the output of the wire feed device ( 1 ) a height-adjustable and / or pivotable with respect to the rolling direction deflection device is preferably provided deflection roller ( 48 ). 26. Wire EDM machine with one on one machine frame arranged workpiece holder, one by the workpiece holder guided wire electrode, the is withdrawn from a wire supply reel Guides to and from the workpiece holder guided and fed to a collecting container, marked by a wire feeder after at least one of protection claims 1-25.