JPS6154532B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a roll electrical discharge machining method for finishing the outer peripheral surface of a roll-shaped workpiece (hereinafter simply referred to as a roll) with a constant surface roughness by electrical discharge machining.

Conventionally, when finishing the surface of steel strip rolling rolls, especially cold rolling rolls, with a satin finish, a method has been adopted in which hard metal particles such as shots and grit are projected onto the polished roll surface to form impressions on the roll surface. It was getting worse.

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.

However, in recent roll processing methods,
In order to shorten processing time, processing using multi-segmented electrodes has come to be performed. In this way, when the number of divisions of a multi-segmented electrode becomes very large, in order to prevent the division processing efficiency from decreasing and to make the mechanical structure stable, it is necessary to A head column (hereinafter referred to as the head and column as one unit) is provided, and a split electrode is attached to each head column, and during machining, electrical discharge machining is performed while moving the plurality of head columns in the direction of the rotation axis of the roll. Methods of doing this have begun to be attempted.

Fig. 1 is for explaining a conventional roll electric discharge machining method using a multi-segmented electrode. A workpiece roll supported horizontally by bearings 2 and 2'; 4 is the roll 3;
A roller 5 chucking one end of the roller 5 is a roll rotation drive device installed on the bed 1, which rotates the roller 4 and rotates the roll 3. 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 transverse feed drive device 7 and a feed screw 8. 9, 9' are head columns fixed on the base 6; 10, 10' are electrode holders mounted on the head columns 9, 9'; 11, 1;
1' is connected to the holder 1 through the insulating plates 12, 12'.
A plurality of electrodes 11 and 11' are mounted at equal pitches at 0 and 10', and these electrodes 11 and 11' are made of a copper plate having a shape shown in a perspective view in FIG. It is formed of
Moreover, they are formed in the same shape. 13 is the processing tank held on the roll 3, 14 is the processing tank 1
The machining fluid 14 that overflows from the machining tank 13 is passed through and is supplied to the machining tank 13 again. Further, reference numerals 15 and 15' are pulse power supply devices that connect the above-mentioned electrodes 11 and 11' and the roll 3.
are connected to form a discharge between them. In the figure, the positive electrode is connected to the electrodes 11 and 11', and the negative electrode is connected to the roll 3, but processing can also be performed in the reverse direction. Further, the spindle feeding of the electrodes 11, 11' in a direction perpendicular to the machined surface of the roll 3 is carried out by each head column 9,
It is performed independently at 9'.

In such a configuration, conventionally, the roll 3 and the electrode 11 are connected to each other while rotating the roll 3 by the celery 4.
11' to perform electrical discharge machining, and furthermore, the base 6 is slid left and right by the action of the feed screw 8, and the roll 3 is slid left and right.

In the case of this conventional method, the stroke of the machining feed of the head columns 9, 9' in the direction of the roll rotation axis (hereinafter abbreviated as head column machining feed) is
If the mounting pitch (hereinafter abbreviated as electrode mounting pitch) in the direction of the roll rotation axis of 1 and 11' is larger or smaller than P, a uniform matte surface will not be obtained. The total machining length (hereinafter abbreviated as total machining length) Li in the roll rotation axis direction is expressed by the following equation as shown in FIG.

Li=P×i+d…(1) However, Li: Total machining length P: Electrode mounting pitch i: Number of electrodes in the roll rotation axis direction (hereinafter abbreviated as the number of electrodes) d: Width of the electrode in the roll rotation axis direction (Hereinafter, abbreviated as electrode width) Therefore, by selecting the number i of electrodes used for machining, electric discharge machining of rolls having various machining lengths Li can be performed. However, if the length L corresponding to the desired surface to be machined and the total machining length Li do not match, when machining is performed using i electrodes, the fourth
As shown in the figure, the following equation (2) holds true.

L _i-1 <L < Li...(2) However, L _i-1 : Total machining length when the number of electrodes is (i- ₁ ) Li: Total machining length when the number of electrodes is i L: Desired Work Surface Length In this situation, the processing position of one of the electrodes 11, 11' will deviate from the desired work surface of the roll during the process of feeding the head columns 9, 9'. In the case shown in Fig. 4, when machining is started by aligning the left end surface of the left end electrode with the left end of the desired surface of the roll and the head column is fed rightward, the right end electrode This indicates that the machining position deviates from the desired surface of the roll to be machined. Furthermore, when the right end electrode and the right end of the desired surface to be processed of the roll are aligned and the processing is fed to the left, the processing position of the left end electrode will be deviated from the desired surface to be processed of the roll. That is, if a part of the machining position of the electrode deviates from the desired surface to be machined of the roll and machining is continued, the total machining length will not match the length of the desired surface to be machined. Furthermore, if the end of the desired surface of the roll to be machined is the end face of the body of the roll, uneven wear of the electrode occurs due to uneven electrode consumption, as shown in FIG. If the next machining is performed using such an electrode that has become uneven, the electric discharge will be concentrated at the tip of the electrode that has become uneven, making it impossible to machine the desired surface of the roll into a uniform satin surface. Become.

The present invention has been made in view of the above points, and it is possible to stop electrical discharge machining using the electrode that has begun to deviate when the machining position of the electrode begins to deviate from the desired surface of the roll during machining. Therefore, good electrical discharge machining can be performed on the desired length of the machined surface.

The method of the present invention will be explained below with reference to the drawings.

FIG. 6 is for explaining one embodiment of the method of the present invention, and the same or corresponding parts as in FIG. 1 are given the same reference numerals, and the explanation thereof will be omitted. In the figure, 16 is a control device that controls power supply from the pulse power supply devices 15, 15' to the electrodes 11, 11'. Further, 17 to 24 are switches, which are provided in the power supply lines between the pulse power supply devices 15, 15' and the electrodes 11, 11', and whose opening and closing are controlled by the control device 16.

In such a configuration, a detection device (not shown) that detects when either electrode 11 or 11' is removed from the desired surface to be processed, or a memory value preset to a value corresponding to the desired surface to be processed is provided. Accordingly, it is detected that the electrode has moved away from the desired surface to be processed.

Next, based on this detection signal or preset value, the control device 16 is actuated to open the switch corresponding to the electrode that has deviated from the desired surface to be machined, and to stop electrical discharge machining using that electrode. . Further, at this time, forcibly separating the electrode from the roll is useful for preventing contact between the roll and the electrode.

As described above, according to the method of the present invention, electrical discharge machining is stopped at the electrodes that no longer face the desired surface of the roll to be machined. Since it is possible to perform electric discharge machining with good accuracy for the length of the surface to be machined, and even if the length of the surface to be machined changes, the same machining machine can perform the machining, which has the effect of dramatically increasing the practical range.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram for explaining the conventional method, Fig. 2 is a perspective view of the electrode, Fig. 3 is an explanatory diagram showing the total machining length, and Fig. 4 shows the machining position of the right end electrode at the desired location on the roll. FIG. 5 is an explanatory diagram showing the case where the electrode comes off the machined surface, FIG. 5 is an explanatory diagram showing uneven wear of the electrode, and FIG. 6 is a schematic configuration diagram for explaining the method of the present invention. In the drawings, the same reference numerals indicate the same or equivalent parts, and in the drawings, 3 is the roll, 7 is the column traverse feed drive device, 9 and 9' are the head columns, and 11 and 1.
1' is an electrode, 15, 15' is a pulse power supply device, 16
is the control device.

Claims (1)

[Claims] 1 A plurality of head columns equipped with electrodes facing the roll-shaped workpiece are provided, and the plurality of head columns are moved in the direction of the rotational axis of the roll-shaped workpiece to create a satin finish on the outer peripheral surface of the roll-shaped workpiece. In a method for electrical discharge machining of a roll-shaped workpiece to be finished, electrical discharge machining is performed by moving the head column in the direction of the rotation axis of the roll-shaped workpiece, and one of the plurality of electrodes is connected to the roll-shaped workpiece. A method for electric discharge machining of a roll-shaped workpiece, characterized in that electric discharge machining at the electrode is stopped by detecting that the electrode no longer faces a desired surface of the workpiece.