JPS5921730B2 - Electric discharge machining equipment for roll-shaped workpieces - Google Patents

Description

Detailed Description of the Invention 25 This invention is a roll-shaped workpiece that finishes the outer peripheral surface of a roll-shaped workpiece with a matte finish with a constant surface roughness (makes the roll-shaped workpiece a matte-like uneven surface). This invention relates to electrical discharge machining equipment for objects.

Hereinafter, the roll-shaped workpiece will be simply referred to as a roll. 30 Conventionally, for example, when finishing the surface of a steel strip rolling roll, especially a cold rolling roll, with a satin finish, there has been a method of projecting hard metal particles such as shot or grid onto the polished roll surface to make impressions on the roll surface. However, in recent years, attempts have been made to perform this type of machining by electric discharge machining 35.

As is well known, electrical discharge machining involves interposing an insulating liquid, such as kerosene, in a narrow machining gap between a power source and a workpiece, and periodically applying a pulse waveform voltage between the electrode and the workpiece. This is a method of machining the surface of a workpiece by causing an electric discharge.

By repeating such electrical discharge machining on the roll surface, rotating the roll in the circumferential direction, and at the same time gradually moving the electrode in the direction of the rotation axis of the roll, the roll surface will undergo a continuous spiral satin finish. The roll surface can be covered with discharge marks. This is a method of uniformly applying a satin finish to the surface of a roll using electrical discharge machining. The resulting satin surface not only has a larger difference in unevenness and a much more regular shape than mechanical impressions made by metal particle projection, but also has a shape that is not affected by the manufacturing method or hardness of the roll. It has many advantages, such as the metal structure on the roll surface being hardened by electrical discharge, making it ideal for use as a rolling roll. However, one drawback of this method is the processing of the roll ends. In other words, in the case of processing by shot blasting, etc., a satin surface is formed uniformly over the entire surface including the roll ends, but when the processing method using the above-mentioned waste electricity is used, both ends of the roll are Unable to process uniformly. next,
This matter will be explained with reference to FIG.

That is, in FIG. 1, reference numeral 1 denotes a roll whose surface is to be matte-finished, and 2 an electrode facing the roll 1 with an electric discharge machining gap in between. 5 is a head column for fixing the electrode holder 4 and controlling the machining gap between the electrode 2 and the roll 1; 18 is a pulse power supply device; 23 is a power supply brush; 11A and 11B are bearings that rotatably support the roll 1; be.

Next, the processing method will be explained.

When processing roll 1, processing pulse power supply device 1
8. Set the processing conditions. These processing conditions determine the roughness of the matte surface of the roll 1 surface. The machining gap between the electrode 2 and the roll 1 is placed in an insulating liquid such as kerosene, and a pulse voltage is applied to the machining gap by the power supply device 18 to generate an electric discharge, thereby performing electrical discharge machining. At the same time, the roll 1 is rotated and the electrode 2 is gradually moved in the direction of the rotation axis of the roll 1, for example from left to right in the figure. That is, the electrode 2 processes the surface of the roll 1 while moving in a spiral manner.

The speed at which the electrode 2 is fed in the direction of the roll rotation axis is selected, for example, at such a speed that the entire surface of the roll 1 is covered with a matte surface once the electrode 2 passes through the roll 1. In the case of machining with a surface roughness of 18μRmax, if the roll diameter is about 600φ, the above feed rate is 2.5
About mm/min is appropriate. Further, the rotational speed of the roll 1 should not be too slow. It is possible to process the entire surface even if the electrode width is weak and the electrode 2 moves in one rotation of the roll, but although there is almost no difference visually, there are streaks on the surface of the roll 1 that are undesirable as a rolling roll. It remains in a spiral shape. Therefore, within the range in which electrical discharge machining is stable, it is desirable that the rotational speed of the jaw 1 be high. That is, the faster the rotational speed of the roll 1 is, the smaller the amount of processing per rotation of the roll is, and the possibility that spiral streaks will remain on the roll 1 is eliminated.

In this way, a uniform satin surface is formed over the entire surface of the roll 1. However, as described above, the above processing method cannot be applied to processing both ends of the roll 1. If the machining is finished when the electrode 2 reaches the end of the roll 1 where the machining is completed, the minimum necessary machining conditions are set to create a satin finish on the roll surface when machining the center part. , an unprocessed part with a width corresponding to the width of the electrode 2 remains at the end of the processed roll 1, and if the feeding speed of the electrode 2 is slowed only when processing the finished end of the roll 1, the processing of the roll 1 is completed. The amount of machining increases at the end, and uniform machining cannot be expected over the entire surface. Furthermore, if the process is continued until the electrode 2 comes off the roll 1, it will come off the end of the roll 1 where the machining is finished, the machining area will gradually decrease, the amount of machining per unit area will increase, and the electrode 2 will become the entire surface of the roll 1. Compared to when the roll is in contact, the machining depth gradually becomes deeper and a spiral step is formed on the surface of the roll 1.

Therefore, it is not possible to uniformly process the finished end of the roll 1.

Furthermore, uniform processing cannot be expected at the processing start end of the roll 1 for exactly the same reason, and therefore there is a drawback that uniform processing of the roll cannot be achieved.

In order to improve this drawback, the inventors conducted repeated experiments and research and detected the change in the machining area that occurs when machining the end of the roll 1, and based on this detection signal, the machining current per unit area was kept constant. It has been found that by controlling the process, both ends of the roll 1 can be processed uniformly.

To explain this in detail, if the electrode 2 is moved, for example, from left to right in FIG. 1 and processing is continued, the electrode 2 will eventually protrude from the right end of the roll 1. In other words, the processing area of the electrode 2 gradually decreases. If the processing continues as it is, the amount of processing per unit area of the roll 1 will increase as described above, and as a result, the roll 1 will have spiral streaks. In order to eliminate this problem, it is possible to make the amount of machining per unit area constant, and for this purpose, the machining current may be decreased in accordance with the decrease in the unit area. That is, the position of the electrode 2 in the roll rotation axis direction is detected by a position detection device, this detection signal is converted into an electric signal by a conversion device, and the output electric signal of this conversion device causes the pulse waveform generated from the pulse oscillation device to stop, for example. The pause time control device is controlled to increase the time.

Even if the pause time changes, there is no effect on surface roughness or electrode wear, so only the machining speed changes depending on the machining area so that the amount of machining per unit area remains the same.

Therefore, the surface of the roll 1 can be processed uniformly from the center to the ends of the roll 1. As described above, the entire surface of the roll 1 can be processed uniformly except for the left end. Also, the left end of roll 1 is
Move electrode 2 in the opposite direction from the electrode position where machining first started.
If the processing is carried out while moving from the right to the left in the figure at the same speed, the left end of the roll 1 can also be uniformly processed in the same way. However, the above-mentioned matters regarding machining the left end of roll 1 apply when electrode 2 is not worn out, and in reality, electrode 2, which is machined on the right end of roll 1, has a machining surface that is worn out. Since it has lost its flatness, it cannot be used to process the left end of the roll 1, and the electrode 2 must be replaced.

However, when electrode 2 is replaced, it is very difficult to adjust the discharge gap, etc. to make the left end of the roll have a uniform machined surface with the machined parts of the center and right ends of the roll, and in the end, there is almost no difference when visually inspected. However, the left end of the roll and the center and right end parts of the roll are processed unevenly, which is not desirable for a rolling roll. In order to further improve this drawback, the inventors conducted repeated experiments and research and found that the above electrode (hereinafter referred to as the main electrode) was developed.

It has been found that by providing an electrode (hereinafter referred to as an auxiliary electrode) exclusively for machining the ends of the roll in addition to the above, it is possible to finish both ends of the roll to a uniformly machined surface with the center of the roll. However, it has been found that if the auxiliary electrode is provided, the entire surface of the roll cannot be processed uniformly unless a predetermined relationship is established between the main electrode and the auxiliary electrode in the processing start or end positions relative to the roll.

Note that if an electrode with the same width as the machining surface of roll 1 is used, what has been described so far becomes unnecessary, but since roll 1 is very long, it is necessary to make the machining gap between roll 1 and the electrode uniform. It is very difficult to do this, and it is not possible to use an electrode that has the same width as the processed surface of the roll 1, as this will result in uneven processing.

This invention focuses on these matters, and provides an electrical discharge machining device for a roll-shaped workpiece that can uniformly machine the entire surface of the roll using a main electrode that processes the center of the roll and an auxiliary electrode that processes the ends of the roll. This is what we provide.

An embodiment of the present invention will be described below with reference to FIGS. 2 and 3.

In Fig. 2, 1 is a roll whose surface is to be matte-finished, and 2A is a main electrode made of a copper plate or the like that faces the roll 1 through a processing gap and is used to process the central part of the roll. It is composed of divided electrode pieces 2a to 2g, and is fixed to the multi-divided electrode pieces 2a to 2g via an insulator 3 to an electrode holder 4 at equal intervals in the roll axis direction. 2B is an auxiliary electrode made of a copper plate or the like that faces the roll 1 through a processing gap and processes both ends of the roll 1, and the width in the roll axis direction is equal to the width of the multi-segmented electrode pieces 2a to 2g forming the main electrode 2A. The width of the auxiliary electrode 2B is substantially the same as the width of one electrode piece 2a in the roll axis direction, and the auxiliary electrode 2B is fixed to the electrode holder 4 via the insulator 3.

5A and 5B are head columns for fixing the electrode holder 4 and controlling the machining gaps between the main electrode 2A and the auxiliary electrode 2B and the roll 1, respectively; 6A and 6B are head columns 5A,
5B is a mounting base, 7A and 7B are sliding shafts that slide the mounting bases 6A and 6B in the direction of the arrow shown in the figure (the direction of the shaft axis);
A and 8B are feed screws for the mounting bases 6A and 6B, and 9A and 9B are position detection devices for the main electrode 2A and the auxiliary electrode 2B in the roll axis direction, which are used to calculate the machining area of the main electrode 2A and the auxiliary electrode 2B.

10 is a head; 11A and 11B are bearings that rotatably support the roll 1; 12 is a drive device that rotationally drives the roll 1 that is not supported by the bearings 11A and 11B via a coupling device 13; and 14 is a drive device that rotates the roll 1. This pressing device 14 is a pressing device that presses and moves in the axial direction, and this pressing device 14 also serves as a device containing a built-in power supply brush 23 that supplies processing energy for processing the roll 1, and also carries one bearing 11B. .

Reference numeral 15 denotes a motor with a speed reducer mounted on the pressing device 14, and the output shaft 16 is threaded, and this threaded portion is screwed into the threaded portion of the holding member 17 fixed on the bed 10. There is.

That is, when the motor 15 with a reduction gear is driven, the motor 15 with a reduction gear, the pressing device 14, and the bearing 11B move together in the roll axis direction. 18 is a processing pulse power supply device, 19 is a position detection device 9 for the auxiliary electrode 2B.
A conversion device that converts the signal B into an electric signal, 20 a rest time control device that receives the signal from the conversion device 19 and controls the rest time of the discharge pulse waveform, 21 a pulse generator, and 22 a machining pulse in the machining gap. A switching device for supplying voltage, 23 is a power supply brush, 24 and 25 are first and second detection devices such as limit switches and photoelectric switches, and the contacts are configured to close when the auxiliary electrode 2B moves to a processing start position, which will be described later. has been done.

Reference numeral 26 designates a third detection device similar to the detection devices 24 and 25 described above, and is configured such that its contact closes when the main electrode 2A moves to the processing start position. 27 is a limit switch that detects that the roll 1 has been carried into the processing start position determined by the main electrode 2A and the auxiliary electrode 2B;
A fourth detection device such as a photoelectric switch is configured so that its contact point opens when the roll 1 is carried to the processing start position. Reference numeral 28 is an electromagnetic contactor, and the first to fourth detection devices 24 to 28 are electromagnetic contactors. 27 is connected in series.

29 is a single-phase power supply device for energizing the electromagnetic contactor 28, 30 is a three-phase power supply device for driving the motor 15 with a reduction gear, 31 is an overcurrent protection device, and 32 is a normally open contact of the electromagnetic contactor 28. .

In order to reverse the speed of the motor 15 with a speed reducer, an electromagnetic contactor and a detection device (not shown) are provided to reverse the phase.

The electric discharge machining apparatus of the present invention is configured as described above, and next, preparations for starting machining will be explained.

First, a motor (not shown) drives the feed screws 8A and 8B to move the main electrode 2A and the auxiliary electrode 2B to the processing start position, that is, the roll axis at the electrode piece 2a, which is one of the multi-divided electrode pieces 2a to 2g of the main electrode 2A. It is positioned at a position where the center line g that bisects the directional width substantially coincides with the center line g that bisects the roll axial width of the auxiliary electrode 2B, and at the time of this positioning, the first to third detection devices 24 26 detects this, closes the contact, and the electromagnetic contactor 28 is energized.

Simultaneously with this operation, a moving device such as a crane (not shown) moves the roll 1 to be subjected to satin finish to the bearing 11A.
Install it on 11B. Note that the processing start position of the roll 1 requires very high precision, so it is difficult to accurately position the roll 1 to this processing start position using the transport device. Therefore, by driving the motor 15 with a reduction gear after installing the roll 1 on the bearings 11A and 11B, the pressing device 14 is
is moved to the left in the figure, and the roll 1 is pressed and moved.

Note that at this time, the roll 1 does not slide on the bearing 11B, but
It moves while sliding on the bearing 11A. and roll 1
When the main electrode 2A and the auxiliary electrode 2B move to the processing start position determined by the main electrode 2A and the auxiliary electrode 2B, the fourth detection device 27 detects this and opens the contact. As a result, the excitation of the electromagnetic contactor 28 is released and its normally closed contact 32 is opened, and the motor 1 with a reduction gear
5 is stopped, preparations for starting machining are completed. Next, processing of the roll 1 will be explained.

That is, by driving the feed screws 8A and 8B by a motor (not shown), the main electrode 2A is moved from left to right in the figure, and the auxiliary electrode 2B for machining the left end of the roll is moved from right to left in the figure.
Processing is carried out while simultaneously gradually moving the auxiliary electrode 2B for processing the right end of the roll from left to right in the figure.

When machining the area where the main electrode 2A machining section and the auxiliary electrode 2B machining section of the roll 1 overlap, if the same machining conditions are given to the multi-divided electrode pieces 2a to 2g of the auxiliary electrode 2B and the main electrode 2A, the roll 1 At the left end of the main electrode 2A, the multi-divided electrode piece 2a and the auxiliary electrode 2B have substantially the same width in the roll axis direction, and the center lines dividing the roll axis width into two substantially coincide with each other. Therefore, as shown in FIG. 3, the auxiliary electrode 2B processes the unprocessed part of the multi-divided electrode piece 2a of the main electrode 2A, and the unprocessed part of the auxiliary electrode 2B is processed by the main electrode 2A. When the multi-divided electrode piece 2a is processed, this portion eventually has a substantially uniform surface roughness. Note that FIG. 3 is exaggerated to facilitate understanding of the above explanation, and A shows the processed portion of the auxiliary electrode 2B, and B shows the processed part of the auxiliary electrode 2B and the multi-segmented electrode piece 2a of the main electrode 2A. , C is the processed part of the multi-segmented electrode piece 2a of the main electrode 2A, D is the processed part of the multi-segmented electrode piece 2a and multi-segmented electrode piece 2b of the main electrode 2A, and E is the processed part of the multi-segmented electrode piece 2 of the main electrode 2A.
This is the processed part b.

Also, at the right end of the roll 1, there is also an auxiliary electrode 2B for right end processing.
At the start of machining, the multi-divided electrode piece 2g of the main electrode 2A is
If this is stopped, this area will also have a uniform surface roughness for the same reason as above. Therefore, when machining the portion of the roll 1 where the machining portion of the main electrode 2A and the machining portion of the auxiliary electrode 2B overlap, the same machining conditions are applied to the multi-divided electrode pieces 2a to 2g of the auxiliary electrode 2B and the main electrode 2A. .

The main electrode 2A applies T to the center of the roll by keeping the machining conditions the same as at the start of machining, and at the same time
If the roll is moved by one pitch of ~2 g, the central part of the roll can be processed substantially uniformly. This is a multi-divided electrode piece 2a-2
If g is moved by -pitch, the adjacent multi-segmented electrode piece will process the unprocessed part of the adjacent multi-segmented electrode piece, and
This is because it is designed and arranged to coincide with the machining start position of the auxiliary electrode 2B at the right end of the roll. As described above, the central part of the roll and the lap part between the main electrode 2A and the auxiliary electrode 2B can be processed uniformly, but if the processing of both ends of the roll at the auxiliary electrode 2B is continued, the auxiliary electrode 2B will eventually become the part of the roll 1. It protrudes from the edge.

In other words, the processing area of the auxiliary electrode 2B gradually decreases. If you continue processing as described above, roll 1
The amount of processing per unit area increases, and as a result, spiral streaks are formed on the roll 1. In order to eliminate this problem, it is possible to keep the amount of processing per unit area constant.
To achieve this, the machining current may be reduced in accordance with the reduction in unit area. That is, the position of the auxiliary electrode 2B in the roll axis direction is detected by the position detection device 9, and this detection signal is sent to the conversion device 19.
This detection signal is converted into an electric signal by a converter 19, and the pause time control device 20 is configured to increase the pause time of the pulse waveform generated from the pulse oscillator 21 based on the output electric signal of the converter 19. Control.

Even if the rest time changes, as described above, there is no effect on the surface roughness or electrode wear, so only the machining speed changes depending on the machining area so that the amount of machining per unit area becomes the same.

Therefore, both ends of the roll 1 can also be processed uniformly, and in the end, the entire surface of the roll can be processed uniformly. The rolls are processed in the manner described above. In the above embodiment, the main electrode was moved from left to right in the figure, but it may be moved from right to left, or may be moved back and forth repeatedly.

In either case, it is necessary to have a predetermined relationship with the auxiliary electrode for machining the right end of the roll, as described above. Furthermore, although a multi-segmented electrode is used as the main electrode, it goes without saying that a single electrode may be used as well as the auxiliary electrode.

Furthermore, in the description of the above embodiment, the determination of the machining start point is illustrated and explained in the case where the main electrode and the auxiliary electrode are positioned in a predetermined relationship, and then the roll is positioned. Of course, the machining start point may be determined by setting the auxiliary electrode and the auxiliary electrode in a predetermined positional relationship.

Further, as a starting point for machining the main electrode on the roll surface, the center line that bisects the roll axial width of the auxiliary electrode and the center line that bisects the roll axial width of the main electrode are substantially aligned. Although the point has been illustrated and explained, the point on the roll where the center lines of the two electrodes substantially coincide may be the finishing point of the main electrode, and various design changes may be made without departing from the spirit of the invention. It is possible.

As explained in detail above, according to the apparatus of the present invention, the electrode is composed of a main electrode that processes the central part of the roll in the direction of the rotation axis, and an auxiliary electrode that processes the end part of the roll in the direction of the rotation axis. The main electrode and auxiliary electrode are set in a predetermined positional relationship, and the machining current per unit machining area of the auxiliary electrode is controlled to a constant level, so the entire surface of the roll can be uniformly machined without changing the electrode during machining. , which will have an extremely large effect when implemented.

[Brief explanation of drawings]

FIG. 1 is a schematic block diagram showing a conventional example, FIG. 2 is a schematic block diagram showing an embodiment of the present invention, and FIG. 3 is a diagram for explaining the present invention. Note that the same reference numerals in the figures indicate the same or equivalent parts. 1...Roll, 2A...Main electrode, 2B
...Auxiliary electrode, 9...Position detection device,
18... Pulse power supply device for processing, 19...
... Conversion device, 20 ... Pause time control device, 2
1... Pulse generator, 22... Switching device, 27... Detection device, 28...
...Magnetic contactor.

Claims (1)

[Claims] 1. While rotating the roll-shaped workpiece, an electrode is moved in the direction of the rotation axis of the roll-shaped workpiece, and a processing pulse power supply device is connected between the electrode and the roll-shaped workpiece. An electric discharge machining apparatus for a roll-shaped workpiece, characterized in that the surface of the roll-shaped workpiece is satin-finished, characterized by meeting the following conditions (a) to (e). (a) A main electrode consisting of a plurality of electrode pieces that processes the central part of the roll-shaped workpiece in the axial direction, and a first electrode that processes the respective end parts of the roll-shaped workpiece in the axial direction. and a second auxiliary electrode. (b) Each electrode piece constituting the main electrode and the first
and making the axial width of the second auxiliary electrode that contributes to machining substantially the same. (c) A center line that bisects the axial width of the first auxiliary electrode and a center line that bisects the axial width of the electrode piece constituting the first auxiliary electrode side end of the main electrode. , a point on the surface of the roll-shaped workpiece that is substantially coincident with that of the main electrode and the auxiliary electrode is set as a starting point for processing the main electrode and the auxiliary electrode. (d) A center line that bisects the axial width of the second auxiliary electrode and a center line that bisects the axial width of the electrode piece that constitutes the second auxiliary electrode side end of the main electrode. , a point on the surface of the roll-shaped workpiece that is substantially coincident with that of the main electrode and the auxiliary electrode is set as a processing end point. (e) Controlling the pulse pause width of the processing pulse power supply device so that the processing current per unit processing area of the first and second auxiliary electrodes is constant.