JP2782294B2 - Grinding method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for performing a grinding process by automatically controlling the rotation speed so that the rotation ratio of a rotation speed command value between a grindstone and a workpiece does not become an integral multiple or nearly an integral multiple. .

[0002]

2. Description of the Related Art Conventionally, in an NC cylindrical grinder, a wheel rotation speed N1 and a workpiece rotation speed N2 are inputted by a floppy disk, a paper tape, an MDI, or the like and stored in a program memory as shown in a flowchart of FIG. . At the time of cutting, the grinding wheel spindle motor and the spindle motor are controlled at the revolution speeds N1 and N2 according to the command values stored in this program, and the grinding wheel revolution speed N1 is usually a constant revolution speed in many cases. Generally, a different numerical value is selected as the command value for the workpiece rotation speed N2 depending on the outer diameter of the workpiece.

[0003]

When the rotation ratio (N1 / N2) happens to be an integer or a value close to an integer, the grinding wheel rotation speed N1 and the workpiece rotation speed N2 described in the prior art will be reduced. The result is that one point on or around the same point on the outer periphery of the workpiece is repeatedly ground, resulting in a polygon with the number of peaks in the rotational speed ratio due to the relative vibration of the grinding wheel and the workpiece, resulting in poor roundness. Had problems. The present invention has been made in view of such problems of the prior art, and has as its object the small probability that one point on the grindstone outer periphery repeatedly grinds the same location on or near the workpiece outer periphery. An object of the present invention is to provide a grinding method for obtaining a rotation speed and automatically changing an input rotation speed command value to improve roundness.

[0004]

SUMMARY OF THE INVENTION In order to achieve the above object, a grinding method according to the present invention obtains a rotation ratio α from respective command values of a wheel rotation speed N1 and a workpiece rotation speed N2. , The obtained rotation ratio α is 4 decimal places
Or other than 5 or one decimal place is 4 or 5
Therefore , when there is no end below the second decimal place, the rotation ratio α is converted to an integer to obtain a value A, and 0.4 or 0.5 is added to this value A to obtain a value B. Then, the value N3 is obtained by dividing the value by N3 as the rotation speed of the workpiece in place of the rotation speed N2 of the workpiece. Processing is performed.

[0005]

The rotation speed of the grindstone and the workpiece stored in the program memory is read out, and the rotation ratio α is determined. When the determined rotation ratio is one point on the circumference of the grindstone, one point on the circumference of the workpiece or If within the allowable range set based on a small speed ratio of the probability of repeated grinding near, when read a workpiece rotational speed as it is used, out of the allowable range, times
The conversion ratio α is converted to an integer, and 0.4 or 0.5 is added to the value.
Is divided by the value of the wheel speed to convert the value to an integer, and this value is designated as a new workpiece speed.

[0006]

An embodiment will be described with reference to FIGS. In a cylindrical grinder, a grindstone table 1 is mounted on a guide in the X-axis direction provided on the rear side of a bed (not shown) so as to be movable and positionable, and on a grindstone shaft 2 rotatably supported by the grindstone table 1, The grindstone 3 is detachably fitted, and the grindstone 3 is rotated at a constant rotation speed by a grindstone motor 4. On the other hand, a table (not shown) is movably mounted on a guide in the Z-axis direction provided on the front side of the bed, and the headstock 5 and the tailstock 6 are mounted on the table so that the mounting position can be changed. I have. The workpiece W rotatably supported by the centers 7 and 8 of the headstock 5 and the tailstock 6 is rotated by a spindle servomotor 9 via a not-shown turn.

The block diagram portion of FIG. 1 is a circuit of a portion related to the present invention in the NC device, and the program memory 11 stores a processing program such as a grinding condition input by a floppy, paper tape, MDI, or the like. Part to do. A program interpreting unit 12 reads a machining program, sorts the program into necessary parts, and sends the sorted program. Wheel / workpiece rotation ratio calculation unit 13
Is a part for calculating the rotation ratio α of the wheel rotation speed N1 and the workpiece rotation speed N2 sent from the program interpretation unit 12 by calculation (N1 / N2). The rotation ratio classification unit 14 calculates the obtained α
Whether the number that the decimal point one digit is a fraction of under 5 in two or more digits,
Or a numerical value other than the above, and outputs a signal indicating no change in the workpiece rotation speed N2 to the program interpretation unit 12 in the former case, and outputs a calculation command to the changed rotation speed calculation unit 15 in the latter case. It is.

[0008] The changed rotational speed calculating section 15 converts the value C obtained by adding 0.4 or 0.5 to the value A obtained by converting the rotation ratio α into an integer, and divides N1 by a value C to convert it into an integer. Is a part for calculating. The speed command calculation unit 16 is a part that, when the workpiece rotation speed N2 or N3 is input from the program interpretation unit 12, outputs a speed command corresponding to the workpiece rotation speed N2 or N3. The current command calculation section 17 is a section that calculates a current command from a speed command, and the power amplification section 18 is a section that amplifies the electric power for driving the spindle servomotor 9.
Note that 11 to 12 and 16 to 18 are not different from ordinary NC servo systems.

Next, this embodiment will be described in the order of the flowchart of FIG. In step S1, the grinding wheel rotation speed N1 input and stored in the program memory is read out to the grinding wheel / workpiece rotation ratio calculation unit 13 via the program interpretation unit 12, and the work rotation speed N2 is similarly calculated in step S2. Is read. In step S3, the grinding wheel / workpiece rotation ratio calculator 13 calculates the rotation ratio α by calculation (N1 / N2). Then either rotated ratio calculated in step S4 alpha is one digit decimal point there are two digits following fraction 4 or 5 is confirmed, If yes step S
In step 5, N2 is designated as the workpiece rotational speed as it is. In the case of no, in step S6, a new rotation speed N3 instead of N2 is calculated by the changed rotation speed calculation unit 15.

In the method of calculating N3, first, the rotation ratio α is converted to an integer (INT) to obtain A, 0.5 is added thereto to obtain B, and N1 is divided by B to convert it to an integer (INT). Then N
Ask for 3. If you apply numerical values to this calculation method,
For example, the input grinding wheel rotation speed N1 = 2000 rpm. Assuming that the workpiece rotation speed N2 = 199 rpm, A = INT (2000/199) = INT (10.05025) = 10 B = A + 0.5 = 10.5 N3 = INT (2000 / 10.5) = INT (190.476) = 19
0 rpm. The rotation ratio in this case is N1 / N3 = 2000
/ 190 = 10.526. Note that INT is a program term meaning integer conversion, and the grindstone rotation speed N1 is constant. Also, B = A + 0.4 can be set, and in this case, the rotation ratio has a fraction whose first digit after the decimal point starts with 4. Next, in step S7, the calculated rotation speed N3 is sent to the program memory 11 and designated as a work rotation speed instead of N2. In step S8, grinding is performed by rotating the grindstone 3 at a constant rotation speed N1 and the workpiece W at an input rotation speed N2 or a changed rotation speed N3.

[0011]

Since the present invention is configured as described above, the following effects can be obtained. The rotation ratio of the input rotation speed command value of the grindstone and the workpiece automatically changes the rotation of the workpiece so that the probability that one point on the circumference of the grindstone repeatedly grinds at or near the same position on the circumference of the workpiece is minimized. Since the grinding is performed by changing the number, the roundness of the workpiece is not reduced by the influence of the mutual vibration of the grinding wheel and the workpiece, and the machining accuracy is stabilized.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a cylindrical grinding machine of the present embodiment and a block diagram of a control circuit.

FIG. 2 is a flowchart for explaining the operation of the embodiment.

FIG. 3 is a flowchart of a conventional grinding method.

[Explanation of symbols]

3 Wheel 4 Wheel motor 9 Spindle servomotor 14 Rotation ratio classification unit 15 Changed rotation speed calculation unit W Workpiece

Claims (1)

(57) [Claims] A rotation ratio α is obtained from respective command values of the input grinding wheel rotation speed N1 and workpiece rotation speed N2, and when the obtained rotation ratio α is other than 4 or 5 with one decimal place.
Or one decimal place is 4 or 5 and two decimal places or less
When there is no end, the rotation ratio α is converted to an integer to obtain a value A, 0.4 or 0.5 is added to this value A to obtain a value B, and the grinding wheel rotation speed N1 is divided by the value B to obtain a value N3. By determining this value N3 as the workpiece rotation speed in place of the rotation speed N2 of the workpiece, grinding is performed at a rotation ratio such that one digit after the decimal point is 4 or 5 and a fraction below 2 digits. And grinding method.