JPS63295178A - Grinder control method - Google Patents

Abstract

PURPOSE:To enhance the roughness and cylindricity of the surface to be ground by controlling a cross feed motor so that the grinding force in the normal direction becomes constant, and by controlling a grinding wheel drive motor so that the grinding force in the tangential direction becomes constant. CONSTITUTION:The grinding force in the normal direction FN is sensed, and a cross feed motor 5 is controlled so that the sensed value becomes constant, while the grinding force in the tangential direction FT is sensed and a grinding wheel drive motor 7a is controlled so that this sensing becomes constant. Therefore, the grinding force in the tangential direction FT is maintained constant even though it tends to increase with decreasing dia. of the grinding wheel 3, and thus the grinding performance will not vary. Even though the grinding force in the tangential direction FT is controlled constant, the grinding ability tends to drop due to drop of the peripheral linear speed of the grinding wheel 3 with decreasing dia. of it, which causes that the grinding force in the normal direction FN tends to increase, but the angle of deflection of the grinding wheel shaft 3a does not vary because the grinding force in the normal direction FN is also maintained constant. This improves both the roughness and cylindricity of the ground surface to a great extent.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for controlling a grinding machine, and more particularly to a method for improving the roughness and cylindricity of a grinding surface.

[Prior art]

In general, a grinding machine consists of a cutting table whose cutting is fed by a cutting motor, a swivel table which is rotatably mounted on the cutting table so as to be rotatable around a vertical axis and which is swivel-driven by a swivel motor, and a workpiece which is mounted on the swivel table. A main shaft and a main shaft drive motor having a chuck for mounting, a grindstone table, a wheel head provided on the grindstone table, a grindstone attached to the wheel head, a grindstone drive motor that drives the wheel head, and a grindstone dresser. It is equipped with such things as

When grinding a workpiece with a grinding machine, the workpiece and grindstone are rotated, and the swivel table is rotated by an angle corresponding to the deflection angle of the grindstone shaft, thereby keeping the axis of the workpiece parallel to the axis of the grindstone. Grind while feeding the cutting table in this state.

During this grinding, as shown in FIG. 5 according to the embodiment, a horizontal normal grinding force F,4 (hereinafter referred to as normal (referred to as force Fs) and tangential grinding force FT, which is mainly caused by the torque of the grindstone drive motor and is transmitted to the workpiece W through frictional force.
(hereinafter referred to as tangential grinding force Ft) acts on the workpiece W, and a grinding force F, which is a Peltor resultant force of this normal grinding force F and the tangential grinding force FT, acts on the workpiece W.

During grinding, the diameter of the grinding wheel decreases as grinding progresses as the grinding wheel wears out and the grinding wheel is dressed many times during grinding. Normally, a constant amount of power is supplied to the grinding wheel drive motor to control its rotation speed and torque. Since the tangential grinding force FT increases as the grinding wheel diameter decreases (
Since the grinding performance is improved by increasing the tangential grinding force FT, the normal grinding force FN becomes smaller.

Since the tangential grinding force FT governs the grinding performance, as the tangential grinding force F7 increases, the surface roughness of the ground surface increases. In addition, the normal grinding force FM greatly affects the deflection angle of the grinding wheel shaft, so if the normal grinding force F changes, the grinding surface becomes tapered, the cylindricity of the grinding surface worsens, and the grinding accuracy decreases. I will do it. However, the grindstone shaft is elastically deformed in the feed direction of the cutting table by the normal grinding force F, and at the same time is also elastically deformed by the reaction force of the tangential grinding force F7.

BACKGROUND ART Conventionally, methods for controlling grinding machines have been proposed to improve the roughness and cylindricity of the ground surface.

For example, Japanese Patent Application Laid-Open No. 51-143983 describes a technique for detecting the deflection of a grindstone shaft and controlling the cutting speed via a cutting motor so that the deflection becomes constant. This is intended to maintain the normal grinding force F8 constant and improve the accuracy of the cylindricity of the ground surface.

Furthermore, Japanese Patent Publication No. 53-34036 describes a technique for detecting the power supplied to a grindstone drive motor and controlling the cutting feed rate so that the power becomes a set value.

This is intended to improve the roughness of the ground surface by keeping the tangential grinding force F7 constant.

[Problem that the invention seeks to solve]

As described above, the technique of grinding by keeping the tangential grinding force F7 constant and the technique of grinding by keeping the normal grinding force F9 constant will be discussed with reference to FIG. 10 according to the embodiment.

In the figure, point O is the center of the grinding wheel when no load is applied, point 0.1 is the center of the grinding wheel, point O6 is the center of the grinding wheel at the beginning of grinding, and point O is the center of the grinding wheel when the tangential grinding force F7 is controlled constant. The center of the grindstone when the diameter of the grindstone becomes small, point ON, is the center of the grindstone when the diameter of the grindstone becomes small when grinding is performed by controlling the normal grinding force FN to be constant.

After the start of grinding, the normal grinding force F due to the cutting feed and the tangential grinding force F due to the torque of the grinding wheel act,
Since the grinding force F which is the Peltor resultant force of and FT acts,
The center of the grinding wheel is 0°, and the grinding point at this time is P. Therefore, the machining radius of the workpiece becomes the line segment OwWo.

At the start of grinding, the spindle is swiveled via the swivel table by an angle corresponding to the deflection angle of the grindstone spindle deflected in the horizontal direction by the normal grinding force FM. ) is generally adjusted and ground so that they are parallel to each other.

As the grinding progresses, the diameter of the grinding wheel becomes smaller, and as mentioned above, the tangential grinding force F7 and the normal grinding force F.

Although the magnitude of is changed, when controlling the normal direction grinding force FN to be constant as in the former publication, the center of the grinding wheel shifts from 00 to ON, the grinding point becomes Ps,
The machining radius of the workpiece is the line segment 0°WN. In this case, the normal grinding force Fs is kept constant, but since the tangential grinding force F7 increases, the deflection angle of the grindstone shaft changes toward the increasing side, and as a result, the grinding point becomes PN. Since the tangential grinding force FT increases significantly, the grinding performance increases and the roughness of the ground surface deteriorates.

On the other hand, when controlling the tangential grinding force F7 to be constant as in the latter publication, the center of the grinding wheel shifts from 00 to Ol, the grinding point becomes P7, and the machining radius of the workpiece becomes line segment 08Wa. In this case, since the tangential grinding force Ft is controlled to be constant, the grinding performance is kept constant and the roughness of the ground surface is reduced. However, as shown in the figure, as the normal direction grinding force FM becomes smaller and the grinding force F becomes smaller, the deflection angle of the grinding wheel shaft becomes smaller, the degree of taper of the grinding surface increases, and the cylindricity of the grinding surface decreases. , the grinding point at this time is point Pa.

When the normal grinding force FH is controlled to be constant as described above, the roughness of the ground surface is not improved, and the cylindricity of the ground surface is only improved to some extent. Also, the tangential grinding force F
When T is controlled to be constant, the roughness of the ground surface is improved, but a problem remains in terms of cylindricity of the ground surface.

Means for Solving Problem C] The method for controlling a grinding machine according to the present invention detects the grinding force in the normal direction of the grinding force when grinding with the grinder, and detects the grinding force in the normal direction among the grinding forces. In addition to controlling the cutting feed motor so that the cutting force is constant, the tangential grinding force of the grinding force is detected, and the grindstone shaft drive upper is controlled so that the tangential grinding force is constant.

C action] In the method for controlling a grinding machine according to the present invention, the normal grinding force is detected and the cutting feed motor is controlled so that it becomes constant, and the tangential grinding force is detected and it becomes constant. Since the grinding wheel drive motor is controlled in this way, even if the tangential grinding force tends to increase as the grinding wheel diameter decreases, it is maintained constant and the grinding performance does not fluctuate. In addition, even if the tangential grinding force is controlled to be constant, as the diameter of the grinding wheel decreases, the grinding performance tends to decrease due to the decrease in the circumferential speed of the grinding wheel, and the grinding force in the normal direction is likely to increase. Since the directional grinding force is also maintained constant, the deflection angle of the grinding wheel shaft does not change.

〔Effect of the invention〕

According to the method for controlling a grinding machine according to the present invention, as explained above, the grinding performance of the grinding machine and the deflection angle of the grinding wheel shaft are each maintained constant during grinding, so that the roughness and cylindricity of the ground surface as well as the It will be significantly improved.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

First, FIGS. 1 to 3 regarding the grinding machine 1 to which the present invention is applied.
Provide a brief explanation of the drawing. In FIG. 1, the -X direction is defined as the left side, the X direction is defined as the right side, the -Y direction is defined as the front, and the Y direction is defined as the rear.

Cutting table 2 that supports the spindle 4 and spindle motor 4a
is the table stand IO on the bed 6 by the cutting motor 5.
It is designed to be driven forward and backward in the forward and backward directions relative to the
The main shaft 4 and the main shaft motor 4a are fixed on a swivel table 11 placed on the cutting table 2, and the swivel table 11 is rotatable around a vertical swivel pin lla. An arm llb protruding leftward is provided at the center of the left edge of the table 11, and a screw shaft 12 screwed into a screw nut of the arm llb is disposed facing forward and backward. It is driven by a swivel drive motor 13 provided on the bracket 2a.

A grindstone table 8 supporting a wheel head 7 and a grindstone drive motor 7a is driven forward and backward relative to the bed 6 in the left and right directions by a grindstone table drive motor 9.

A workpiece W is attached to the chuck 4b of the main spindle 4, and the inner peripheral surface of the workpiece W is ground by the grindstone 3 at the tip of the grindstone shaft 3a of the wheel head 7. After the grindstone table 8 is moved to the left and the grindstone 3 is inserted into the shaft hole of the workpiece W, the cutting table 2 is moved forward or backward to perform grinding.

During the above grinding, the cutting table 2 is cut by the cutting motor 7 motor 5.
As shown in Figs. 4 and 5, when the grinding wheel 3 is fed forward into the cut, friction is caused from the grinding wheel 3 to the workpiece W due to the normal grinding force FM as a reaction force of the cutting feed force and the rotational torque of the grinding wheel 3. The tangential grinding force Fa transmitted through the force acts,
A grinding force F acts as a vector resultant force of the normal grinding force F and the tangential grinding force Ft.

Due to the normal grinding force FM and the tangential grinding force FT, the grinding wheel shaft 3a has a normal grinding force F, as shown in FIG.
It is elastically deformed in the opposite direction (cut feed direction) and also in the opposite direction to the tangential grinding force FT.

Therefore, at the beginning of grinding, the swivel drive motor 13 is driven to swivel the swivel table 11, and a predetermined swivel angle θ is set so that the axial center of the workpiece W and the axial center of the grindstone 3 are parallel to each other as shown in FIG. Adjust and grind.

Next, a method of controlling the grinding machine I will be explained.

The method of controlling this grinding machine 1 is to detect the normal grinding force F and the tangential grinding force F, respectively, and
The cutting motor 5 is controlled so that N is constant, and the grindstone drive motor 7a is controlled so that the tangential grinding force Ft is constant, thereby significantly reducing the roughness and cylindricity of the ground surface. It is something that we try to improve.

In order to detect the normal grinding force F and the tangential grinding force FT, as shown in FIGS. 6 and 7,
F8 detection magnetic sensor 14a facing close to the front side of the outer peripheral surface of a and F facing close to the lower side of the outer peripheral surface of the grindstone shaft 3a
A magnetic sensor 14b for T detection is provided, and detection signals from these magnetic sensors 14a and 14b are output to a control unit (path shown).

The control unit is provided with a cutting motor control system shown in FIG. 8 and a grindstone drive motor control system shown in FIG. 9.

The control system in FIG. 8 shows an example of a control system that controls the rotational speed of the cutting motor 5 so that the normal grinding force FM detected by the detection magnetic sensor 14a becomes a set value. A normal direction grinding force setter 16, a subtracter 17 that subtracts the detection signal of the FN detection magnetic sensor 14a from the output signal of this setter 16, and a a cutting operation panel 18 that commands the cutting operation by the cutting motor 5; and a cutting motor control device 19 that receives a command signal from the cutting operation panel 18 and the output signal of the subtracter 17 and outputs driving power to the cutting motor 5.
When the detected value of the normal grinding force FM is smaller than the set value, a signal of 10 is output from the subtractor 17, the input signal to the cutting motor control device 19 becomes large, and the cutting motor 5 is controlled. Since the rotation speed is controlled to increase, when the normal grinding force F approaches the set value and the detected value of the normal grinding force F2 is larger than the set value, the rotation speed of the cutting motor 5 increases, contrary to the above. Since the grinding force F is controlled to decrease, the normal grinding force F approaches the set value.

The control system in FIG. 9 shows an example of a control system that controls the rotational speed of the grindstone drive motor 7a so that the tangential grinding force Fa detected by the FT detection magnetic sensor 14b becomes a set value. A tangential grinding force setting device 33, a subtractor 34 that subtracts the output signal of the setting device 33 from the detection signal of the F1 detection magnetic sensor 14b, and a grinding wheel according to the material, shape, and dimensions of the workpiece W and the type of the grinding wheel 3. a grindstone operation panel 35 that commands the grinding operation by the drive motor 7a; a grindstone drive motor control device 36 that receives the command signal from the grindstone operation panel 35 and the output signal of the subtracter 34 and outputs driving power to the grindstone drive motor 7a; When the detected value of the tangential grinding force Fa is larger than the set value, the subtractor 34 outputs a signal of 10, the input signal to the grindstone drive motor control device 36 increases, and the grindstone drive motor 7a Since the rotation speed is controlled to increase, the tangential grinding force F7 approaches the set value.

When the detected value of the tangential grinding force F is smaller than the set value, contrary to the above, the rotation speed of the grindstone drive motor 7a is controlled to decrease, so that the tangential grinding force F approaches the set value.

In the above manner, the normal grinding force F and the tangential grinding force Fa are controlled to be constant (set values), and the effect of controlling in this way is as follows. become.

In Fig. 10, when controlling as described above, even if the grinding wheel diameter decreases as the grinding progresses, the normal direction grinding force FM
and tangential grinding force F7 are each maintained constant, so
The center of the grinding wheel moves only by the amount by which the diameter of the grinding wheel decreases from the 0° center of the grinding wheel at the beginning of grinding, and the grinding point is point P. hold the position of
The machining radius of the workpiece W is the line segment OwWo as in the initial stage of grinding.

As is clear from FIG. 10, the machining radii O, W of the conventional technology that controls the normal grinding force FH constant, and the machining radius Ow of the conventional technology that controls the tangential grinding force FT constant.
When compared with Wy, it can be seen that this grinding control is superior.

That is, if the normal grinding force F8 and the tangential grinding force F7 are controlled to be constant as in this grinding control, even if the grinding wheel diameter decreases, the deflection angle of the grinding wheel shaft 3a will remain constant throughout the entire grinding period. Since the swivel angle is held constant, causes other than errors in setting the swivel angle at the initial stage of grinding, which cause the grinding surface to become tapered, are eliminated. In this way, the cylindricity of the ground surface is significantly improved and there is almost no tapering.

Furthermore, even if the tangential grinding force FT is likely to increase as the grinding wheel diameter decreases, the rotation speed is increased and the tangential grinding force Ft is controlled to be constant, so the grinding performance of the grinding wheel 3 is maintained constant. , the roughness of the ground surface is maintained as well as at the initial stage of grinding.

Even if the tangential grinding force FT is controlled constant,
As the grinding wheel diameter decreases, the circumferential speed of the grinding wheel 3 decreases, so the grinding performance decreases and the normal grinding force FH tends to increase, but the normal grinding force F is controlled to be constant.
No fluctuations in the normal grinding force FM occur.

Next, a modification of the control system and detection system of the grinding machine 1 will be described.

(11 As shown in Fig. 11, the control unit 1
5 is the F8 detection magnetic sensor 14a and F? An A/D converter 22 that receives detection signals from the detection magnetic sensor 14b and converts them into A/D; an operation panel 23 that inputs and sets grinding conditions; and signals from the A/D converter 22. Input/output ink face 24 that receives input/output ink face 24
A CPU 25 (central processing unit W) connected to the CPU 25 via a data bus etc., and a ROM 26 (read only memory) and a RAM 27 connected to the CPU 25 via a data bus etc.
(random access memory), and from the input/output interface 24, a spindle motor drive circuit 28, a cutting motor drive circuit 29, a swivel drive motor drive circuit 30, a grindstone drive motor drive circuit 31, and a grindstone table drive motor drive Control signals are output to the circuits 32 and 32, respectively.

The ROM 26 is loaded with a control program for controlling each motor 4a, 5, 7a, 9, 13 based on setting signals from the operation panel 23, and detection signals from the FM detection magnetic sensor 14a and the FT detection magnetic sensor 14b. Then, as above, the cutting motor 5 is adjusted so that the normal direction grinding force FM becomes the set value.
A control program for controlling the grindstone drive motor 7a so that the tangential grinding force Fa becomes a set value is stored in advance.

Since the control routine is extremely simple, detailed explanation will be omitted.

(2) Instead of the magnetic sensors 14a and 14b, various detection devices such as an electric micrometer, an air micrometer, and an optical micrometer can be used.

In addition, the normal direction grinding force F, 4 detection means may be configured as shown in FIG. 12 or FIG. 13, for example.

That is, in the case shown in FIG. 12, the rotation speed signal of the cutting motor 5 (detected by the rotation speed sensor) and the diameter signal of the grinding inner circumferential surface measured by the in-process gauge 32 are used to determine the rotation speed of the grinding wheel shaft 3a. The amount of deflection is determined, and the grinding force FM in the normal direction is determined from the amount of deflection. In addition, in the case shown in FIG. 13, the diameters of the grinding inner circumferential surface of the workpiece W at two locations in the axial direction are detected using a pair of in-process gauges 32, and the deflection angle of the grinding wheel shaft 3a is determined from the difference in diameter. The normal grinding force FM is determined from the corner. In addition, the reference numeral 15 in the figure
B is a control unit similar to that in FIG.

On the other hand, the tangential grinding force Fa converts the voltage of the electric power supplied to the grindstone drive motor 7a into a potential transformer.
In addition, the current is detected by a current transformer, the rotation speed of the grindstone drive motor 7a is determined by a rotation speed sensor, etc., and the tangential grinding force Fa is determined based on the detected voltage, the detected current, and the detected rotation speed. You can also do this.

[Brief explanation of the drawing]

The drawings relate to an embodiment of the present invention, and FIG. 1 is a plan view of the grinding machine, FIG. 2 is a front view of the same, FIG. 3 is a side view of the same, and FIG. 4 is a deflection angle and a swivel angle of the grinding wheel shaft. Fig. 5 is an explanatory diagram showing the normal grinding force, tangential grinding force, and grinding force acting on the workpiece from the grindstone, and Fig. 6 shows the magnetic sensor for F0 detection and the magnetic sensor for F7 detection. Fig. 7 is a plan view of the main parts, Fig. 8 is a block diagram of the control system for the cutting motor, and Fig. 9 is a block diagram of the control system for the grindstone drive motor. , Fig. 10 is an explanatory diagram of the machining radius when controlled by each control method including the conventional technology, Fig. 11 is a configuration diagram of an example of the control system of the entire grinding machine, and Figs. 12 and 13 are diagrams for each method. It is a block diagram which shows an example of a linear grinding force detection means. 1. Grinding machine, 3. Grinding wheel, 5. Cutting motor,
7a...Grinding wheel drive motor, F...Normal direction grinding force, Fa...Tangential direction grinding force, F...Grinding force,
14a...F, detection magnetic sensor, 14b...F7
Detection magnetic sensor, 15. Control unit, 16. Normal direction grinding force setter, 17. Subtractor, 19. Cut motor control device, 29. Cut motor drive circuit, 31. Grinding wheel drive motor. drive circuit,
33...Tangential grinding force setting device, 34...Subtractor, 36...Grinding wheel drive motor control device. Patent applicant: Mazda Motor Corporation Figure 1 Figure 2 Figure 4 Figure 5 j Figure 7 Figure 10

Claims (1)

[Claims] (1) When grinding with a grinder, the grinding force in the normal direction of the grinding force is detected, the cutting feed motor is controlled so that this normal direction grinding force is constant, and the tangential direction of the grinding force is A method for controlling a grinding machine, comprising: detecting a grinding force in a direction, and controlling a grindstone shaft drive motor so that the grinding force in a tangential direction is constant.