JPH0428489B2 - - 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 a steel strip rolling roll, especially a cold rolling roll, with a satin finish, a method has been adopted in which hard metal particles such as shots or grits are projected onto the polished roll surface to create impressions on the roll surface. However, in recent years, attempts have been made to perform this type of machining using 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 a discharge. This is a method of machining the surface of a workpiece depending on the situation.

By repeating such electric discharge machining on the roll surface, rotating the roll in the circumferential direction, and at the same time moving the electrode gradually in the direction of the rotation axis of the roll, the roll surface will undergo a continuous spiral-like satin finish. , the roll surface can be covered with discharge marks. This is a method of uniformly applying a satin finish to the roll surface using electrical discharge machining.

The pear-shaped surface obtained in this way has a large difference in unevenness compared to mechanical impressions made by metal particle projection.
Moreover, not only is the shape much more regular, but the shape is not affected by the manufacturing method or hardness of the roll.
Furthermore, since the metal structure on the roll surface is hardened by electrical discharge, it has many advantages, such as being optimal as a rolling roll.

However, in recent roll processing methods,
In order to shorten the machining time, machining has come to be performed using multi-segmented electrodes, and when the number of divisions becomes very large, in order to prevent the division processing efficiency from decreasing, and to improve the mechanical structure. In order to make the roll stable, there are multiple head columns facing the roll (hereinafter referred to as the head and column as one unit).
Attempts have been made to provide a method in which a split electrode is attached to each head column, and electrical discharge machining is performed while a plurality of head columns are moved in the direction of the rotational axis of the roll during machining.

FIG. 1 is a schematic diagram showing a roll electric discharge machining apparatus using a general multi-segmented electrode. In the figure, 1
is a bed, 2 and 2' are bearings installed on the bed 1, 3 is a roll of the workpiece supported horizontally by the bearings 2 and 2', 4 is a celery that chucks one end of the roll 3, and 5 is a bed 1 The roll rotation drive device installed on the top rotates Kelley 4,
It 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, 1;
0' is an electrode holder attached to the head column 6;
Reference numerals 11 and 11' denote a plurality of electrodes that are attached to the holders 10 and 10' at equal pitches through insulating plates 12 and 12'.
The two are opposed to each other with a machining gap in between, and are made of a copper plate having the shape shown in a perspective view in FIG. 2, and are also formed in the same shape. 13 is a machining tank held on the roll 3; 14 is a machining fluid supplied into the machining tank 13 by a pump (not shown);
The machining fluid 14 overflowing from the machining tank 3 is passed through and is supplied to the machining tank 13 again. Also, 15 and 15' are pulse power supply devices,
Each electrode 11 and the roll 3 are connected to form a discharge.

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 opposite manner. Also, the spindle feed of the electrodes 11, 11' in the direction perpendicular to the machined surface of the roll 3 is carried out by each head column 9, 9'.
is carried out independently.

In such a configuration, when machining a roll, electric discharge is generated between the roll 3 and the electrodes 11, 11' while the roll 3 is rotated by the celery 4, and electric discharge machining is performed. 8, the electrodes 11, 11' are caused to slide left and right on the roll 3 together with the head columns 9, 9'.

By the way, when processing a roll into a matte finish using a plurality of head columns, it is necessary to process various rolls having different processed surface lengths.

In this case, the machining feed width by the electrodes attached to the plurality of head columns does not reach the length of the machining surface of the roll, and the entire surface machining may not be possible. In order to solve this problem, the number of head columns should be increased in advance to correspond to the length of the machined surface of the roll, but the head column part is made with great precision, and it is difficult to add more head columns. However, a considerable number of processing pulse power supplies are required to be connected thereto, and the machine becomes very expensive both mechanically and electrically, making it uneconomical.

The first aspect of this invention was made in view of the above-mentioned problems.
It is an object of the present invention to provide a method for electric discharge machining of rolls that can economically perform electric discharge machining of rolls longer than a plurality of head columns.

The second aspect of the invention is that when performing electric discharge machining on a roll that is longer than a plurality of head columns, multi-stage machining,
That is, to provide a roll electric discharge machining method that can shorten machining time and obtain a uniform machined surface when machining is performed in multiple stages from electrical machining conditions with large surface roughness to electrical machining conditions with small surface roughness. With the goal.

First, the first aspect of this invention is to take into account all the various roll processing surface lengths requested by users,
The most efficient and economical number of head columns is set, and for rolls that deviate from this and have a machined surface length that is greater than the total width of each head column width and less than twice this total width. The present invention provides a method for performing processing.

That is, the first electrical discharge machining is performed by aligning one end of the roll with one end of the head column, and then the entire head column is moved in the axial direction of the roll by a drive device and a feed screw, and the other end of the roll and the other end of the head column are moved. The ends are matched, and only the head column with the electrode attached to the position facing the range of the roll that was not processed in the first machining is driven, and the electrode is servo-fed in the direction opposite the roll while controlling the servo. Perform the second electric discharge machining.

In this processing method, there is no need to add a head column to correspond to the length of the roll 3, and processing can be carried out economically and efficiently.

Next, the second aspect of the present invention is a processing method in which rolls having a processing surface length that is larger than the total width of each head column width and twice or less than this total width are processed in multiple stages into a uniform satin surface. It provides: Here, multi-stage processing is used to shorten processing time when obtaining a finely machined surface on a roll machined surface.
This is a processing method in which the electrical machining conditions are changed over two or more times in order from a large surface roughness to a small surface roughness, and the processing is continued to gradually produce a finer surface.

When performing such multi-stage machining, first, as shown in FIG.
One end 101 of 6 and one end of the roll 3 are made to face each other,
The part of the roll 3 where the head columns 101 to 106 face each other is subjected to the first multi-stage machining process in which the electrical machining conditions are changed, and then the entire head column is moved as shown in FIG.
The other end 106 of 1 to 106 and the other end of the roll 3 are opposed to each other, and only the head columns 105 and 106 facing the unprocessed portion 3a of the roll 3 are driven.
It is conceivable to perform a second multi-stage processing.

When such processing is performed, as shown in FIG. 5, a boundary 3b between the rolls 3 between the first multi-stage processing and the second multi-stage processing occurs,
There is a problem in that the surface roughness of this boundary 3b is different from the surface roughness of the other roll 3 surfaces.

As shown in Fig. 6, which shows the details of the surface of the roll 3, if multi-stage processing is performed at the first position and then multi-stage processing is performed at the second position 3a, there will be However, the desired fine surface roughness that was machined in the first stage is re-processed depending on the electrical machining conditions of the large surface roughness in the first stage of the second stage, and the desired fine surface roughness that was machined in the second stage is The boundary portion 3b was performed under the electrical machining conditions of 2
Due to the insufficient number of times the electrode passes, the desired fine surface roughness cannot be obtained, and the surface roughness is close to the large surface roughness of the first step, and the surface is cut over a certain width. This results in areas with different roughness.

The roll 3 having portions with different surface roughness is completely worthless as a product, and the second invention was created by focusing on this point.

This processing method will be described below.

In order to eliminate the portions 3b having different surface roughness as described above, it is sufficient to perform the steps , , , in FIG. 7. That is, head columns 101 to 106
One end 101 and one end of the roll 3 are opposed to each other (hereinafter, this position is referred to as the first processing position), and processing is performed under electrical processing conditions with large surface roughness in the first stage. Next, the head columns 101 to 106 are The other end of the head column 106 and the other end of the roll 3 are moved to face each other (hereinafter, this position will be referred to as the second processing position), and processing is performed under the same electrical processing conditions as in the previous processing. Next, head columns 101-1 again
06 to the first machining position, perform machining under the electrical machining conditions according to the desired second-stage microsurface roughness, and then move the head columns 101 to 106 to the second machining position. Processing is carried out under the following electrical processing conditions.

In the above case, when the first stage machining is completed at the second machining position, the head column is returned to the first machining position before starting the second stage machining.
This means that when the first stage machining is completed at the second machining position, the second stage machining is performed at the second machining position, and then
The head column may be returned to the first machining position and the second stage machining may be completed at the first machining position. In this case, there is no difference in the number of times the electrode passes between the first and second machining stages at the boundary between the first and second machining positions, so there is no concern that parts with different surface roughness will occur near the boundary. . Moreover, although the above example is a case of two-stage machining, the same effect can be obtained even in the case of multi-stage machining of two or more stages.

As mentioned above, in the first method of this invention,
If the machined surface roughness of the rolls is long compared to multiple head columns, perform the first electric discharge machining on one end of the roll facing the head column, then move the head column to the other end of the rolls and perform the first electric discharge machining. Since the parts that are not subject to machining during machining are subjected to electrical discharge machining, rolls longer than the head column can be machined more economically and efficiently without the need to add a head column. .

In addition, in the second method of the present invention, when the roll is longer than a plurality of head columns, the process of the first invention described above is repeated for each electrical machining condition to perform multi-stage processing, so that the roll has no surface roughness. The effect is that there are no different areas and a uniform pear surface can be obtained in a short time.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram showing an electrical discharge machining apparatus for explaining a roll electrical discharge machining method, Fig. 2 is a perspective view of an electrode, and Figs. 3 to 6 are for explaining disadvantages of multi-stage machining of long rolls. and FIG. 7 are diagrams for explaining multi-stage processing according to the present invention. In the drawings, the same or corresponding parts are denoted by the same reference numerals. 3 is a roll, 9 and 9' are head columns, and 11 and 11' are electrodes.

Claims (1)

[Scope of 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 rotation axis of the roll-shaped workpiece, and the roll-shaped workpiece is In the electric discharge machining method for a roll-shaped workpiece, in which the outer circumferential surface of the roll-shaped workpiece is finished with a satin finish while performing electrode feeding servo in the opposite direction with an electrode facing the workpiece, When the machined surface length is greater than the total width of each head column width and less than twice this total width, the first electrical discharge machining is performed at a position where one end of the roll-shaped workpiece and one end of the head column face each other. Then, move the entire head column to a position where the other end of the roll-shaped workpiece faces the other end of the head column, and then move the entire head column to a position that faces the range of the roll-shaped workpiece that was not subject to machining in the first machining. A method for electric discharge machining of a roll-shaped workpiece, characterized in that a second electric discharge machining is performed by driving only a head column to which an electrode is attached. 2. 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 and are faced to the roll-shaped workpiece. In an electric discharge machining method for a roll-shaped workpiece in which the outer peripheral surface of the roll-shaped workpiece is finished with a satin finish while servoing the electrodes in opposite directions, the machining surface length of the roll-shaped workpiece is as described above. When the width is larger than the total width of each head column and less than twice this total width, the first electric discharge machining is performed at a position where one end of the roll-shaped workpiece and one end of the head column face each other, and then the roll-shaped The entire head column was moved to a position where the other end of the workpiece faced the other end of the head column, and the electrode was attached to a position facing the range of the roll-shaped workpiece that was not targeted for processing in the first machining. A method for electrical discharge machining of a roll-shaped workpiece, characterized in that multi-stage machining is performed by repeating a series of machining operations in which only a head column is driven and a second electrical discharge machining is performed for each electrical machining condition.