JPH0692064B2 - Control Method of Inner Profile Grinding without Master Cam - Google Patents

Description

The present invention relates to a control method for performing profile grinding on the inner surface of a housing or the like without using a master cam.

[Conventional technology]

When performing profile grinding on the inner surface of the housing of a hydraulic pump without using a master cam, attach the housing that is the work to the work spindle, rotate the spindle at low speed while controlling the rotation, and use a grindstone that can be rotated at high speed. The grindstone spindle of the grinding wheel is positioned in the reciprocating direction of the spindle, and the profile grinding is performed by feeding the cutting wheel in synchronization with the rotation of the work.

[Problems to be Solved by the Invention]

When the cylindrical work is being rotated as described above, if profile grinding is performed on the inner surface of the work without using the master cam, the grindstone synchronizes with the rotation of the work with respect to the cutting surface of the work. Since the cutting motion (forward and backward motion) can be performed by the cutting tool, the whetstone has a cutting (forward) motion-stop,
Escape (backward) movement-Repeat repeatedly.

In this way, when the grindstone repeats the reciprocating motion due to the cutting, there are many large shift points at the time of the motion, and it is considerably difficult to control the cutting at high speed and with high accuracy.

However, if high-speed and high-precision inner surface profile grinding can be realized without using the master cam, not only the master cam is not used, but the initial cost can be reduced and the workability can be improved. It is convenient.

An object of the present invention is to provide a control method capable of realizing high-speed and high-precision inner surface profile grinding that does not require such a master cam.

[Means for Solving the Problems]

The present invention has the following configuration to solve the above problems. That is, according to the configuration of the present invention, when the work is supported by the work spindle and is rotated, the work stone is reciprocated back and forth along the rotation axis of the work in synchronization with the rotation of the work stone, which is being rotated at a high speed. In servo control of internal profile grinding that does not use a master cam that makes a cutting motion, the acceleration data of the command value related to the cutting motion of the whetstone can be arbitrarily set from the command value of the cutting motion of the whetstone. When the time-divisional formation is performed with time, and when the acceleration data of the command value indicates the preset predetermined content, the main command is to create the original command value by inserting the command value indicating zero acceleration for an arbitrarily settable time. It is a feature.

[Work]

At the time of cutting feed of the grindstone, for example, from the feed command value, for example, a time point at which the feed acceleration suddenly changes is grasped in advance, and in the command value that causes a sharp change in the acceleration, a command indicating zero acceleration instead of the command value. By inserting the value, it is possible to prevent or mitigate vibrations and the like during operation caused by a sharp change in acceleration.

〔Example〕

Next, an embodiment of the control method of the present invention will be described with reference to the control block of FIG.

1 is the work spindle of the internal grinding machine, 1a is the chuck,
Reference numeral 1b is a shaft, and 1c is an encoder attached to the shaft 1b so as to output the rotation speed (angle) of the spindle as a pulse signal. W is a workpiece that is a workpiece to be attached to the chuck 1a, and a cylindrical body formed in the housing of the oil pump is chucked as the workpiece W here. The axis 1b is
The rotation is controlled and driven by a servo motor or the like (not shown).

An inner surface grinding head 2 is provided with a grindstone 2b at the tip of a spindle 2a, and the spindle 2a can be rotated at a high speed by a high speed motor 2c such as an air motor.
Although not shown, the spindle 2a is supported by a ball bearing or the like.

3 is a tool rest on which the grinding head 2 is mounted.
On the carriage 4, the cutting feed (forward) and the escape (reverse) operations are performed by the rotation of the servomotor 3Z.

The reciprocating mechanism of the cut feed is performed by a feed screw, a hydraulic cylinder, or the like. Here, the forward / reverse rotation of the motor 3Z mounted on the carriage 4 and the feed screw 3a for transmitting this rotation,
And a nut member 3b provided on the side of the tool rest 3 that receives the rotation of the screw 3a. 3c is this turret 3
This is a length measuring device of an appropriate type that detects the amount of movement in the reciprocating movement of the pulse signal.

On the other hand, the carriage 4 is mounted on the bed of the machine, equipped with a feed mechanism such as a feed screw and a nut member so as to be able to reciprocate along the axial direction of the spindle 2a. The reciprocating motion is driven by the forward and reverse rotations of.

When facing the inner surface without using the master cam,
To obtain the profile you want to form on the inner surface of the workpiece W,
The cutting feed of the tool rest 3 is drive-controlled in synchronization with the rotation of the work spindle 1b rotated at a relatively low speed, for example, 30 to 50 rpm. The method of the present invention is applied to this control system to be described below.

Reference numeral 5 denotes a setting unit which sets a command value in a format for causing the tool rest 3 to perform a predetermined amount of cutting feed when the rotation angle of the work spindle 1b is a predetermined value.

This set value is converted into a pulse signal in the command unit 6 and formed into a command value in a format that can be supplied to the servo amplifier 8, and is supplied to the pulse-wise modulation (PWM) type servo amplifier 8 via the comparison unit 7. The output of the amplifier 8 drives the motor 3Z.

Here, the pulse encoder 1c of the work spindle 1b
The detection pulse by is supplied to the command unit 6. Command unit 6
Then, when the set value related to the rotation angle (number) of the spindle 1b and the detected value of the rotation angle (number) supplied from the encoder 1c of the spindle 1b match, the rotation angle (number) of this spindle is corresponded. A command value for cutting feed is supplied from the command unit 6 to the servo amplifier 8.

In the present invention, when the command value set in the setting unit 5 is supplied to the servo amplifier 8 from the command unit 6, first, before the supply,
From the sequence of command values, acceleration data relating to cutting feed, which is time-divided appropriately in unit time, is formed in the acceleration data forming unit 9 every suitable unit time.

The acceleration data formed above is successively compared with the discrimination data set in the setting unit 15 in the discrimination unit 12. here,
Since the discrimination data is set with the content indicating the sign reversal of the acceleration and the fluctuation of the acceleration value in the acceleration data, when the acceleration data has such content,
A command value meaning zero acceleration is supplied from the correction command value setting unit 11 to the command unit 6 via the determination unit 12 and is inserted into the corresponding part in the original command value sequence, thus created. The command value is supplied to the servo amplifier 9.

On the other hand, when the motor 3Z operates by receiving the output of the servo amplifier 8 which is operated by being supplied with the command value generated as described above, in the present invention, the current feed amount of the tool rest 3 is from the length measuring device 3c. It is returned to the comparison unit 7. When the detected value to be fed back and the preceding cutting feed amount command value match, the command unit 6 supplies the position and speed command values relating to the next cutting feed, and so on. The cutting feed of the grindstone 2b is controlled in synchronization with the rotation angle (number).

In the present invention, in the internal grinding in which the cutting feed is controlled as described above, the actual acceleration during the reciprocating movement of the cutting motion of the tool rest 3 is always monitored, and the actual acceleration value being monitored is arbitrary. Another object of the present invention is to drive the servo amplifier 8 by a separately set command value when the predetermined value is set to the above.

Hereinafter, this point will be described.

Reference numeral 13 denotes an actual acceleration data forming unit, which is mainly formed of a differentiator that forms the movement amount data supplied from the measuring device 3c into velocity or acceleration data. At an arbitrary sampling cycle that can be set to 10, actual acceleration data during reciprocating cutting motion of the tool rest 3 is sequentially formed.

Reference numeral 14 denotes an acceleration data comparison unit that sequentially compares the acceleration data before and after the acceleration data that is sequentially formed in the acceleration data forming unit 13 at appropriate sampling intervals. The magnitude of the comparison value and the sign inversion are used as the acceleration data. Turret 3 appears
Will show the behavior during the actual cutting movement.

15 is a setting unit configured to set another command value corresponding to the content of the comparison value obtained in the comparison unit 14, for example, beyond the range where the tool post is allowed by the comparison value of the acceleration data. It is formed so that another command value, which means, for example, zero acceleration, can be set in response to a case where it is clear that vibration is occurring. Here, the criterion for the comparison value is empirically or calculated. Further, the other command value may be one other than zero acceleration.

16 is a preset condition (comparison value between acceleration data) for supplying another command value set by the setting unit 15
Is compared with the data comparison value of the actual acceleration supplied from the comparison unit 14, and when the comparison value between the acceleration data matches the setting condition, here, the command value of acceleration 0 is set from the setting unit 15 to the selection unit 8a. This is a discriminating unit for directly supplying to the servo amplifier 8 via. Therefore, at this time, the command value is not supplied from the setting unit 5. In addition, the insertion time of this command value is
Can be set arbitrarily.

Here, the value obtained by comparing the formed actual acceleration data with each other at an arbitrary sampling cycle is an index for detecting a case where the numerical value suddenly increases or decreases or the sign is reversed. Becomes

For example, in the control system that includes the setting unit 5, the command unit 6, the comparison unit 7, and the servo amplifier 8 and drives and controls the cutting feed motor 3Z, the workpiece W is actually machined by a certain command value, and the acceleration at the time of machining is performed. The data is detected by the acceleration data forming unit 9 and the comparison unit 7 of the correction control system, and the actual finish of the grinding process and the above detected acceleration data are correspondingly verified, and the cutting feed rate is determined based on this verification result. It is possible to obtain a section (time) that can be advanced earlier, a section (time) that needs to be delayed, or conditions related to deceleration, stop timing, acceleration timing, etc. Sufficient control accuracy is difficult to obtain at points where the acceleration changes sharply.

Therefore, in order to maintain or improve the control accuracy after high-speed driving at such a point, it is necessary to detect the fluctuation point of the acceleration data or the point where the sign is reversed in the actual value of the cutting motion command value. It has significance.

〔The invention's effect〕

The present invention is as described above, and in the control of the inner surface profile grinding without using the master cam, when the cutting motion of the grindstone is controlled in synchronization with the rotation of the work spindle, the grindstone repeatedly causes the cutting reciprocation and the accompanying movement. Sudden control and changing of the direction of the incision can be made, but by applying the control method of the present invention, it is possible to alleviate or eliminate the occurrence of vibration and the delay of response even when such various operations are performed at high speed. The unique effect of being able to do is obtained.

Therefore, the present invention is very suitable for controlling internal grinding without using a master cam.

[Brief description of drawings]

FIG. 1 is a block diagram of a control system including a main part of a master camless inner surface grinding machine to which the method of the present invention is applied. 1 ... Work spindle, 1c ... Encoder, 2 ... Grinding head, 3 ... Turret, 3Y ... Feed motor, 3c ... Length measuring machine, 4 ... Reciprocating stand, 5 ... Setting section, 6 ... … Command section, 7
…… Comparison unit, 8 …… Servo amplifier, 9 …… Acceleration data forming unit, 10 …… Reference clock, 11 …… Correction command value setting unit, 12 …… Determination unit, 13 …… Actual acceleration data forming unit, 14
...... Acceleration data comparison unit

Claims (2)

[Claims] 1. When a work is supported and rotated by a work spindle, in synchronization with this rotation, a cutting motion that reciprocates back and forth along the rotation axis of the work is performed on a grindstone that is being rotated at high speed. In the servo control of the inner surface profile grinding that does not use the master cam, it is possible to arbitrarily set the acceleration data of the command value related to the cutting motion of the grindstone from the command value of the cutting motion of the grindstone in an appropriate unit time. A master cam which is divided into parts and which, when the acceleration data of the command value indicates a preset predetermined content, inserts a command value indicating zero acceleration for an arbitrarily settable time to create an original command value. Control method for internal profile grinding without using. 2. When a work is supported and rotated by a work spindle, a cutting motion that reciprocates back and forth along the rotation axis of the work is synchronized with the rotation of the work and is rotated at a high speed. In the servo control of the inner surface profile grinding that does not use the master cam that was made to perform, during the cutting movement of the grindstone, the acceleration data during the cutting movement of the grindstone is formed at an appropriate sampling cycle to constantly monitor the acceleration state. When the acceleration data indicates a preset content, the inner profile without using the master cam is characterized in that the servo command value indicating zero acceleration is directly supplied to the servo control section for an arbitrarily settable time. Grinding control method.