JP2900602B2 - Grinding wheel feed control method for cam grinder - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a grinding wheel feed control method of a cam grinder for grinding a cam surface such as a cam used in a valve mechanism of an internal combustion engine.

2. Description of the Related Art In this type of cam grinder, there is a cam grinder in which a grindstone table is constituted by two moving mechanisms, a lower slide mechanism and an upper slide mechanism. The lower slide mechanism is guided by the bed guide surface, and moves the upper slide mechanism at high speed by on / off driving of the hydraulic cylinder. In addition, the upper slide mechanism further advances the grinding wheel installed on the upper side from the advanced end position by the lower slide mechanism by driving an electric motor or the like, and grinds the cam surface of the workpiece according to a desired cam profile. In order to give

For example, as shown in FIG. 5, when a start command is applied, the grinding wheel 50 is advanced at a high speed by the lower slide mechanism from the last retreat position to the fast-forward advance end position (fast-forward section) S, and the grinding wheel 50 moves forward. When the end position is reached, the upper slide mechanism further advances the low-speed movement from the rapid advance end position to the grinding start position (approach section). When the grinding wheel 50 reaches the grinding start position,
The feed position of the upper slide mechanism is controlled by the position control data set based on the desired cam profile, and the grinding wheel 50 is moved back and forth in the processing movement section C,
The cam surface 51 is processed.

By the way, if an abnormal situation occurs while the cam surface 51 is being ground, the emergency stop button may be pressed and the machining operation may be stopped urgently. Simply stopping the rotation drive of the grinding wheel) and the feed drive of the grinding wheel 50 may cause the grinding wheel 50 to bite into the cam surface 51 depending on the feed position of the grinding wheel. Therefore, at the time of an emergency stop, the grinding wheel 51 is moved backward at a high speed by the lower slide mechanism as shown in FIG.

Problems to be Solved by the Invention In the conventional grinding wheel feed control method as described above, when the start button is pressed after an emergency stop, the grinding wheel is advanced by the lower slide mechanism, and the grinding operation is restarted. When the hydraulic cylinder of the slide mechanism is moved forward most, the grinding wheel 50 is pinched forward by the inertial force and bites into the cam surface 51, thereby deteriorating the processing accuracy.

Means for Solving the Problems A grinding wheel feed control method for a cam grinding machine according to the present invention comprises:
In order to solve the above problems, a first slide mechanism for moving the grinding wheel at a high speed in a rapid traverse section between a last retreat position and a predetermined forward end position; A second slide mechanism for moving the grinding wheel based on the cam profile at the time of grinding and moving at a low speed in an approach section between the grinding operation start position and a main spindle on which the workpiece is mounted. On the other hand, in the grinding wheel feed control method of the cam grinding machine for moving the grinding wheel in the direction intersecting, when a machining operation stop command is issued during the grinding operation, the grinding wheel is retracted by the approach section by the second slide mechanism. It is characterized in that it is made to be.

Operation When a machining operation stop command is issued during the grinding operation, the grinding wheel is moved backward by the approach section by the second slide mechanism to cause interference between the grinding wheel and the workpiece. When the machining operation is restarted, the grinding operation can be performed by moving the grinding wheel forward in the approach section by the second slide mechanism.

Embodiment An embodiment of the present invention will be described in detail with reference to the drawings.

First, the configuration of a grinding machine to which one embodiment can be applied will be described with reference to FIG. 1 and FIG. First
FIG. 2 is a perspective view showing a main configuration of the grinding machine, and FIG. 2 is an explanatory view schematically showing a grinding wheel feed mechanism of the grinding machine.

In FIG. 1, reference numeral 1 denotes a cam surface provided on a table 2.
This is a headstock that rotationally supports a spindle 4 on which a workpiece 3 having 3a is mounted. The spindle 4 is rotationally driven by a spindle servomotor 5 fixed to the headstock 1. A pulse generator 6 is attached to the spindle servomotor 5.
6. Feedback control is performed by a closed loop formed by a control unit 7 to which a position detection pulse of the pulse generator 6 is given and a servo amplifier 8 to which a speed command is given from the control unit 7.

Reference numeral 9 denotes a headstock for moving the grinding wheel 10 in a direction perpendicular to the rotation axis of the spindle 5, and comprises an upper slide mechanism (second slide mechanism) 11 and a lower slide mechanism (first slide mechanism) 12. The upper slide mechanism 11 includes an upper slide table 14 on which a grinding wheel 10 and a motor 13 for rotating the grinding wheel 10 are mounted, a ball screw 15 for moving the upper slide table 14, and a grinding wheel feed for rotating and driving the ball screw 15. Servo motor 16. Servo motor for grinding wheel feed 16
The feedback control is performed by a closed loop formed by a pulse generator 17 attached to the grinding wheel feed servo motor 16, a control unit 7 to which a position detection pulse of the pulse generator 17 is given, and a servo amplifier 18 to which a speed command is given from the control unit 7. Is done.

The lower slide mechanism 12 is slidably guided on a guide surface 19a of a bed 19 and has a lower slide table 20 on which a grinding wheel feed servomotor 16 is fixed on the upper side, and a lower slide table 20 fixed on the bed 19 and moves back and forth. And a hydraulic circuit 22 that drives and controls the hydraulic cylinder 21. The hydraulic circuit 22 is controlled by a control command given from the control unit 7, and by switching operation of the solenoid valve 24 as shown in FIG. 2, the lower slide table 20 is moved to a retracted position shown by a solid line or an advanced position shown by a two-dot chain line. Move. The forward position of the lower slide table 20 is positioned by pressing the front part of the lower slide table 20 against a stopper provided on the guide surface 19a by the forward drive of the hydraulic cylinder 21.

Reference numeral 25 denotes a switch box provided with a start button 26 for giving a start command for a grinding operation to the control unit 7 and an emergency stop button for giving a stop command to the control unit 7 for urgently stopping the grinding operation. It is.

Next, the operation of this embodiment will be described with reference to the flowchart of FIG. 3 and the operation explanatory diagram of FIG.

When the start button 26 is turned on, a forward command of the hydraulic cylinder 21 is output from the control unit 7 to the hydraulic circuit 22, and the grinding wheel 10 is advanced at a high speed in the rapid traverse section S from the last retreat position to the rapid traverse advance end position. (Step S1).
Then, when the forward command is issued, the control unit 7 starts timer counting, and when the time at which the front portion of the lower slide table 20 comes into contact with the stopper 23 is reached, it is determined that the grinding wheel 10 has reached the fast-forward advance end position. Is performed (step S2). It should be noted that the hydraulic cylinder 20 is kept in a forward pressurized state during a processing operation described later.

When it is determined that the grinding wheel 10 has reached the fast-forwarding forward end position, an approach amount forward command is output from the control unit 7 to the servo amplifier 18, and the grinding wheel feed servo motor is output.
The upper slide table 14 is advanced at a low speed by the approach amount K by the rotation drive of 19 (step S3). By detecting the position of the pulse generator 17, the upper slide table
It is determined whether or not 14 has advanced by the approach amount K (step S4), and the upper slide table 14 has
When the grinding wheel 10 advances only by this distance, the grinding wheel 10 reaches the grinding start position, so that the grinding operation is started (step S5). During this grinding operation, a speed command is given to each of the servo amplifiers 8 and 18 in accordance with the position data stored in the control unit 7 based on a desired cam profile, and the spindle servomotor 5 and the grinding wheel feed servomotor 16 are supplied. Are respectively feedback controlled. The grinding wheel 10 moves back and forth in the processing movement section C by the feedback control.

During the grinding operation, it is determined whether the emergency stop button 27 has been turned on (step S6). If the emergency stop button 27 is not turned on, the grinding operation is repeated until the spindle speed reaches a predetermined number, and when the spindle speed reaches the predetermined number, the grinding operation ends (step S7).

When the grinding operation is completed, the control unit 7
Then, a rotation stop command of the spindle servomotor 5 is output to the servo amplifier 8 and an approach amount retreat command is output to the servo amplifier 18 to retreat the upper slide table 20 by the approach amount K (step S8).

And, from the control unit 7, the hydraulic circuit
A command to retract the hydraulic cylinder 21 is issued to 22, the grinding wheel 10 returns to the last retracted position (step S9), and the operation ends.

If the emergency stop button 27 is turned on in step S6 described above, the control unit 7 outputs a rotation stop command of the main shaft servomotor 5 to the servo amplifier 8 and the hydraulic circuit 22 A reverse command is output and an approach amount reverse command is output to the servo amplifier 18 (steps S10 and S11). Thereby, the grinding wheel 10 retreats at a high speed to the last retreat position.

When the start button 26 is turned on to restart the operation from the emergency stop state, the operations in steps S1 to S4 described above are performed, and the grinding operation is started again from the position where the processing operation is stopped.

As described above, in this embodiment, if there is a stop command during the grinding operation, the grinding wheel 10 is retracted by the approach amount by the grinding wheel feed servo motor 16 together with the rapid traverse retreat operation by the hydraulic cylinder 21. Wheel 10
Is prevented from biting into the cam surface 3a. Further, when the grinding operation is resumed, the grinding wheel 10 is at the position retracted by the approach amount K even if the grinding wheel 10 moves forward in the rapid traverse, so that the situation that the grinding wheel 10 leans forward due to its inertia force and bites into the cam surface 3a does not occur.

In the case where the workpiece 3 having a plurality of cam surfaces 3a is to be ground, when the machining operation of one cam surface 3a is completed, the grinding motor is moved backward by the approach amount by the grinding wheel feed servo motor 16, and the machining operation of all the cam surfaces 3a is performed. As described above, according to the method for controlling the feed of the grinding wheel of the cam grinding machine according to the present invention, the machining operation stop command is issued during the grinding operation. When there is, since the grinding wheel is retracted by the approach section by the second slide mechanism, a situation in which the grinding wheel bites into the cam surface is avoided, and a decrease in machining accuracy due to the situation is prevented.

[Brief description of the drawings]

FIG. 1 is a perspective view schematically showing the overall configuration of a cam grinding machine to which an embodiment of the present invention can be applied, FIG. 2 is an explanatory diagram schematically showing a grinding wheel feed mechanism of the grinding machine, FIG. 3 is a flowchart for explaining the operation of the grinding machine, FIG. 4 is a diagram for explaining a grinding wheel feed control operation, and FIG. 5 is a diagram for explaining a conventional grinding wheel feed control operation. 1 ... headstock, 3 ... workpiece, 3a ... cam surface, 4 ...
Spindle, 5: Servo motor for spindle, 7: Control unit, 8, 18, Servo amplifier, 9: Grinding wheel head, 10 ...
... grinding wheel, 11 ... upper slide mechanism (second slide mechanism), 12 ... lower slide mechanism (first slide mechanism),
14 ... Top slide table, 15 ... Ball screw, 16 ...
... Servo motor for grinding wheel feed, 20 ... lower slide table, 21 ... hydraulic cylinder, 22 ... hydraulic circuit.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B24B 19/12 B24B 47/12 B23Q 5/58

Claims (1)

(57) [Claims] 1. A first sliding mechanism for moving a grinding wheel at a high speed in a rapid traverse section between a last retreat position and a predetermined forward end position, and starting a grinding operation of the grinding wheel at the forward end position and a predetermined grinding operation. A second slide mechanism for moving the grinding wheel based on the cam profile at the time of grinding and moving at a low speed in an approach section between the positions.
In a grinding wheel feed control method for a cam grinding machine that moves a grinding wheel in a direction intersecting a main spindle on which a workpiece is mounted, when a machining operation stop command is issued during a grinding operation, the second slide mechanism is used. A method for controlling the feed of a grinding wheel of a cam grinding machine, wherein the grinding wheel is moved backward by the approach section.