JPS6361131B2 - - Google Patents

Description

[Detailed description of the invention] [Technical field to which the invention pertains] This invention relates to electric discharge machining of a roll, which finishes the outer circumferential surface of a roll-shaped workpiece (hereinafter referred to as a roll) with a constant surface roughness by electric discharge machining. It is about the method.

[Prior art]

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. A method of doing this has begun to be tried.

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 lateral 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, which 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 generate electric discharge and perform electric discharge machining,
Furthermore, the base 6 is slid left and right by the action of the feed screw 8, and the head columns 9, 9' are moved 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) L _i in the direction of the roll rotation axis is expressed by the following equation as shown in FIG.

L _i =P×i+d...(1) However, L _i : Total machining length P : Electrode mounting pitch i : Number of electrodes in the direction of the roll rotation axis (hereinafter abbreviated as the number of electrodes) d : Roll rotation axis of the electrode Width in Direction (hereinafter abbreviated as electrode width) Therefore, by selecting the number i of electrodes used for machining, electric discharge machining can be performed on rolls having various machining lengths Li. However, the length L of the processed surface of the roll (hereinafter referred to as the effective length of the roll)
If and the total machining length Li do not match, when machining with i electrodes, the result will be as shown in Figure 4, and the following
Equation (2) holds true.

L _i-1 <L < L _i ...(2) However, L _i-1 : Total machining length when the number of electrodes is (i-1) L _i : Total machining length when the number of electrodes is i L: effective length of the roll In such a situation, the processing position of one of the electrodes 11, 11' will deviate from the effective length of the roll during the process of processing and feeding the head columns 9, 9'. In the case shown in Fig. 4, when machining is started with the left end face of the left end electrode aligned with the left end of the effective length of the roll and the head column is fed to the right, the right end electrode is machined during machining. It shows that the position is off the edge of the roll. Furthermore, when the right end electrode and the right end of the desired surface of the roll to be processed are aligned and the processing is fed to the left, the processing position of the left end electrode will be deviated from the end of the roll. That is, if a part of the processing position of the electrode deviates from the end of the roll and processing continues, the total processing length will not match the effective length of the roll. Further, when the end portions of the roll are processed, as shown in FIG. 5, uneven wear of the electrodes occurs due to uneven electrode wear. When re-machining is performed using such an electrode that has become uneven, the discharge concentrates on the tip of the electrode that has become uneven, which causes the electrode to wear out, and machining does not proceed until the electrode conforms to the roll shape.

[Summary of the invention]

The present invention has been made in view of the above-mentioned points, and is a roll-shaped workpiece in which the electrode, which is worn out on one side when the end of the roll is processed, quickly conforms to the roll shape when the end of the roll is processed. A method of electrical discharge machining is provided.

In the electric discharge machining method according to the present invention, 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 rotation axis of the roll-shaped workpiece to produce the roll-shaped workpiece. In the electric discharge machining method for a roll-shaped workpiece that finishes the outer circumferential surface of the workpiece, the electrode that comes off from the end of the roll should be machined under low consumption machining conditions when it comes off and moves, and when it is put back together, it should be It is characterized by processing under consumable processing conditions. In this way, the shape of the electrode that has been reduced to one side can be quickly made into a roll shape.

[Embodiments of the invention]

Hereinafter, a method according to an embodiment of the present invention will be explained using 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'.

In such a configuration, when machining is performed so that either electrode 11 or 11' is removed from the workpiece surface of the roll, when machining is performed in a direction where it is further removed from the work surface, machining is performed under low consumption conditions, and when machining is performed in the opposite direction. In other words, the control device 16 operates so that the processing is performed under consumable conditions during the restoring process.

In the embodiment of the present invention, the separated electrode is used as a head for other electrodes, but it is possible to achieve even greater effects by providing a dedicated head.

〔Effect of the invention〕

As described above, according to the method of the present invention, when the machining position of the electrode deviates from the end face of the roll, machining is performed under low-consumption machining conditions to reduce the amount of wear on the electrode on one side, and when the machining process is performed again, Since this is carried out under consumable machining conditions, the electrode that has worn out on one side can be quickly shaped into a roll shape, which has the effect of dramatically increasing the practical range.

[Brief explanation of drawings]

Figure 1 is a schematic diagram for explaining the conventional method, Figure 2 is a perspective view of the electrode, Figure 3 is an explanatory diagram showing the total machining length, and Figure 4 shows that the machining position of the right end electrode is the effective length of the roll. FIG. 5 is an explanatory diagram showing uneven wear of the electrode, and FIG. 6 is a schematic diagram for explaining the method of the present invention. In the figure, 3 is a roll, 7 is a column traverse drive, 9 and 9' are head columns, 11 and 11' are electrodes, 15 and 15' are pulse power supplies, and 16 is a control device. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

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 the electric discharge machining method for a roll-shaped workpiece to be finished, regarding the electrode that comes off from the end of the roll, when it comes off and moves, it is machined under low-consumable machining conditions, and when it is returned, it is machined under consumable machining conditions. Features: Electrical discharge machining method for roll-shaped workpieces.