JPH0226575Y2 - - Google Patents

Description

[Detailed description of the invention] [Technical field of the invention] This invention is based on the invention, in which the head column is aligned with the rotation axis of the roll while maintaining a predetermined distance between the tip of the electrode and the roll-shaped workpiece (hereinafter referred to as the roll). This invention relates to an electrical discharge machining device for a roll that moves the roll in a direction to finish the outer circumferential surface of the roll with a satin finish with a constant surface roughness by electrical discharge machining.

[Prior art] Conventionally, when finishing the surface of a steel strip rolling roll, especially a cold rolling roll, to a matte finish, hard metal particles such as shot or grit are projected onto the polished roll surface to create impressions on the roll surface. A method of attaching it was used.

However, in recent years, attempts have been made to perform this type of machining by electrical discharge machining.

As is well known, electric discharge machining involves interposing an insulating liquid such as kerosene in the narrow discharge gap between the electrode and the workpiece, and periodically applying a pulse voltage between the electrode and the workpiece to generate an electric discharge. This is a method of processing a workpiece by

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 the roll using electrical discharge machining.

The pear surface obtained in this way not only has a larger difference in unevenness and a much more regular shape than mechanical impressions made by metal particle projection, but the shape is also influenced by the manufacturing method and hardness of the roll. Zumata,
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.

Figure 1 is for explaining a roll electrical discharge machining device. In Figure 1, 1 is a bed, 2 and 2' are bearings installed on the bed 1, and 3 is horizontally supported by the bearings 2 and 2'. The roll of the workpiece to be supported, 4 is a roll chucking one end of the roll 3, and 5 is a roll rotation drive device installed on the bed 1, which rotates the roll 3 by rotating the roll 3. It is something that makes you Reference numeral 6 denotes a base, which is configured to be slidable on the bed 1 from side to side in the figure by the action of a column lateral feed drive device 7 and a feed screw 8. 9 is a head column fixed on the base 6, 10 is an electrode holder attached to the head column 9, 11 is an electrode attached to the holder 10, and this electrode 11 is connected to the roll 3 through a machining gap. They face each other and are made of copper plates having the shape shown in a perspective view in FIG. 12 is a processing tank for immersing the processing position of the roll 3 in processing liquid; 13 is a processing liquid supplied into the processing tank 12 by a pump (not shown); the processing liquid 13 discharged from the processing tank 12 is filtered. , and is configured to be supplied to the processing tank 12 again. Further, reference numeral 14 denotes a pulse power supply device, which is connected to form a discharge between each of the electrodes 11 and the roll 3. In the figure, the positive electrode is connected to the electrode 11, and the negative electrode is connected to the roll 3, but processing can also be performed in the reverse direction. Further, the main shaft feeding of the electrode 11 in a direction perpendicular to the processing surface of the roll 3 is performed by a head column 9.

FIG. 3 and FIGS. 4A to 4D are diagrams showing a conventional machining tank, a method of supplying machining fluid, and a method of setting the machining fluid level according to the roll diameter, respectively. ' is a shaft seal, which is divided into an upper side and a lower side, and a pair constitutes one set. When carrying the roll 3 into the processing tank 12, use shaft seals 15, 1 that match the shaft diameter of the roll 3 to be carried.
Select 5', set the lower side first, and roll 3.
After carrying in, set the upper side.

Moreover, when carrying out the roll 3 from the processing tank 12,
Open the stop valve 17 or the electric discharge valve to discharge the machining fluid 13 from the discharge port 16, and then remove the shaft seal 1.
After confirming that the liquid level is lower than the position of the lower holes 5, 15', remove the upper side of the shaft seals 15, 15', and transport the roll 3. After the roll 3 is carried in and the upper sides of the shaft seals 15, 15' are set, the liquid level control plate 18 controls the motor etc. according to the diameter of the body of the carried roll 3 (hereinafter referred to as the roll diameter). It is moved up and down by the used drive device 19, and an overflow surface for the machining fluid 13 is set.

4A to 4D are diagrams illustrating a method of supplying the machining fluid 13 using the liquid level control plate 18 and a method of setting the machining fluid level according to the roll diameter. 4th A
The figure is a left side view when the roll diameter is small, FIG. 4B is a front view, FIG. 4C is a left side view when the roll diameter is large, and FIG. 4D is a front view.

The machining position of the electrode 11 and the roll 3 in electrical discharge machining must be in the machining fluid as explained above, but the liquid level is higher than the machining position as shown by the reference numeral 20 in Fig. 4A. If it is in the position, important mechanical parts such as the electrode holder 10 will get stuck in the machining fluid 13, and sludge may get in there, causing a malfunction. Therefore, it is necessary to consider sealing against the machining fluid 13. The structure of the holder 10 etc. becomes complicated and expensive. Therefore, it is desirable that the liquid level be at the minimum height necessary for machining, but if the liquid level is too low, sparks in the machining area will rise to the liquid level along with the gas that is generated. Since there is a possibility that the machining liquid 13 will catch fire, the liquid level control plate 18 should be kept at a constant height “H” for safety.
The overflow surface is set and the liquid level height is set according to the roll diameter. In the case of a roll electric discharge machine, H=about 50 mm.

A machining fluid supply device such as a machining fluid supply pump 21 supplies the machining fluid 13 passed from the passing device 22 to the machining tank 1.
2, and the shaft seals 15, 15' of the processing tank 12
In order to remove the amount of leakage from the parts, etc. and the sludge generated during processing, the amount is forcibly overblown and returned to the filtration device 22.

As described above, conventionally, a notch is made in the processing tank 12, and a liquid level control plate 18 and a drive device 19 such as a motor are provided in that part.
The overflow surface of the machining fluid 13 is set by varying the height of the machining fluid 13 according to the size of the roll diameter, so that the fluid level height "H" from the machining position is constant. The pump 21 has a constant flow rate and has enough flow capacity to satisfy the amount of leakage from the shaft seals 15, 15', etc. and the amount of machining liquid 13 in the machining tank 12 that is forced to overflow and returned to the overflow device 22. Therefore, a method of supplying the machining fluid 13 has been adopted.

However, in this method, electrical equipment such as the liquid level control board 18 and drive device 19 such as a motor, etc.
Since the mechanical structure is attached, the structure is complicated and expensive, maintenance is required frequently, and since the attachment location is limited to the processing tank 12, space is limited and maintenance is difficult.

[Summary of the idea]

This idea was made in view of the above, and is equipped with a liquid level detector and a machining liquid supply device with variable flow rate.
The distance from the tip of the electrode to the surface of the machining fluid is kept constant regardless of the roll diameter, and it is mechanically very simple and inexpensive, and maintenance is environmentally and space-efficient. The present invention provides a very easy electric discharge machining device for a roll-shaped workpiece.

[Example of idea]

Hereinafter, embodiments of this invention will be described based on the drawings. Fig. 5 is an explanatory diagram of the structure of a machining tank according to an embodiment of this invention, and Figs. 6A to 6D illustrate a method of supplying machining fluid and a method of setting the liquid level height from the machining position to a constant level. It is a diagram. FIG. 6A is a left side view when the roll diameter is small, FIG. 6B is a front view thereof, FIG. 6C is a left side view when the roll diameter is large, and FIG. 6D is a front view thereof. 1st
The same reference numerals as in FIGS. 3, 3, and 4A to 4B represent the same or similar components, and therefore the description thereof will be omitted. A liquid level detector 23 is fixed to the electrode holder 10 and detects the level of the machining liquid. The length of the electrode 11 is fixed, and by attaching the liquid level detector 23 to the electrode holder 10, it is possible to detect the liquid level height from the tip of the electrode, that is, from the processing position, regardless of the roll diameter.
24 is a variable flow rate adjustment device, which is attached to the discharge port side of the pump 21.

The flow rate adjustment device 24 adjusts the amount of machining fluid 13 supplied to the machining tank 12 in response to a signal from the fluid level detector 26, and adjusts the distance from the machining position to the fluid level height regardless of the size of the roll diameter. is maintained at a predetermined value "H". At this time, the discharge port 16 is kept open and the machining fluid 13 is returned to the filter device 22. Therefore, in order to discharge the machining fluid 13 from the machining tank 12, it is sufficient to stop the supply of the machining fluid 13. To adjust the flow rate, an inverter power source or the like may be used to drive the pump 21, and the discharge amount of the pump 21 itself may be made variable. If hunting occurs in the operation of the flow rate regulator 24, create hysteresis characteristics in the control of the flow rate regulator by providing two types of upper and lower limits for the liquid level detector 23, or by providing a sequential time delay. It's good to let it stand. FIG. 7 is a characteristic diagram when flow rate control is provided with hysteresis characteristics. Under the condition that the machining fluid 13 is being discharged at a constant rate, the flow rate adjustment device 24 is repeatedly turned on (opened) and off (closed) every time the fluid level exceeds the hysteresis width to adjust the supply amount. This keeps the liquid level constant.

Note that the flow rate adjustment device 24 may be installed at a location between the pump 21 and the processing tank 12 with a good environment and a space for maintenance.

[Effect of idea]

As explained above, this idea attaches a liquid level detector to the electrode holder, detects the level of the machining liquid from the tip of the electrode, and calculates the supply amount based on the detected liquid level. Because the adjustment is made, the distance from the tip of the electrode to the level of the machining fluid is automatically maintained constant regardless of the roll diameter, making it mechanically very simple, inexpensive, and easy to maintain. A good electrical discharge machining device for roll-shaped workpieces has been realized.

[Brief explanation of the drawing]

Fig. 1 is a diagram explaining an electric discharge machining device for a roll-shaped workpiece, Fig. 2 is a diagram explaining an electrode, and Figs. 3 and 4A to 4D respectively show the structure of a conventional machining tank and machining Figures 5 and 6A to 6D, which explain the method of supplying liquid and setting the machining liquid level according to the roll diameter, respectively show the structure of the machining tank and the supply of machining liquid according to an embodiment of this invention. FIG. 7 is a diagram illustrating the method and the method of setting the machining liquid level according to the roll diameter, and is a characteristic diagram when the flow rate control is given hysteresis characteristics. In the figure, 3 is a roll, 10 is an electrode holder, 1
1 is an electrode, 12 is a machining tank, 13 is a machining fluid, 16 is a discharge port, 21 is a machining fluid supply pump, 22 is a filter device, 23 is a liquid level detector, and 24 is a flow rate adjustment device. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Scope of Claim for Utility Model Registration] A roll-shaped workpiece is installed in a machining tank to which machining fluid is supplied, a head column is provided with an electrode holder holding an electrode facing the roll-shaped workpiece, and the electrode A roll that finishes the outer peripheral surface of a roll-shaped workpiece by electric discharge machining by moving the head column in the direction of the rotation axis of the roll-shaped workpiece while maintaining a predetermined distance between the tip of the roll-shaped workpiece and the roll-shaped workpiece. In an electric discharge machining apparatus for a shaped workpiece, a liquid level detector is attached to the electrode holder and detects a liquid level height of machining liquid from the tip of the electrode, and a liquid level detector is installed in the electrode holder to detect the liquid level height of the machining liquid from the tip of the electrode, and the machining process is performed according to the output of the liquid level detector. An electrical discharge machining apparatus for a roll-shaped workpiece, comprising a machining fluid supply device that supplies fluid and maintains a constant distance from the tip of the electrode to the surface of the machining fluid.