JP2677900B2 - Polishing equipment - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a polishing apparatus for polishing or grinding a workpiece, and in particular, polishing a workpiece by pressing a support member against a tool via an elastic member such as a spring. Or, it relates to a grinding device for grinding.

[Conventional technology]

In polishing or grinding along a complicated curved surface shape such as blade surface polishing of a jet engine blade (hereinafter collectively referred to as polishing), highly accurate finish performance is required.
As a polishing device for performing such polishing, a device is known in which a tool supporting member is pressed against a polishing tool using an elastic member such as a spring, and polishing is performed while pressing a workpiece by the pressing force of the spring. There is.

FIG. 5 is a diagram showing a schematic configuration of a conventional polishing apparatus. The rotational force of the servo motor 101 is transmitted to the polishing apparatus main body 102 by an endless belt, and the pressing member 103 swings freely around the polishing apparatus main body 102 in conjunction with the servo motor 101. Has become.

That is, the rotational force of the servomotor 101 is the polishing apparatus body 1
Through 02, it is converted into vertical movement of the pressing member 103.
A spring 104 is attached to the end of the swinging pressing member 103, and the polishing device body 1 is attached to the other end of the spring 104.
A grinder support member 105 that freely swings around 02 is attached. The grinder 106, which grinds the workpiece 108, is supported by the grinder support member 105, and grinds the workpiece 108 while being pressed by the pressing force of the spring 104.

On the other hand, the angle difference φ between the pressing member 103 and the grinder support member 105 corresponding to the length of the spring 104 or the pushing amount of the spring 104 is detected by the potentiometer 107, and the servo motor 101 is driven so that this angle difference φ becomes constant. .

In this way, the conventional polishing apparatus drives the servo motor 101 so that the pressing amount of the spring 104 becomes constant,
The work piece 108 is polished while maintaining a constant pressing pressure.

[Problems to be solved by the invention]

However, as described above, in the conventional polishing apparatus,
Only the control for keeping the pressing force of the polishing tool against the workpiece constant is performed, and the dynamic characteristics of the system including the spring and the tool have not been considered. Therefore, it was not possible to control the vibration itself when the spring vibrates during polishing.

That is, there is a problem that polishing unevenness may occur due to the vibration of the spring, which causes deterioration of polishing quality.

The present invention has been made to solve such conventional problems, and an object thereof is to provide a polishing apparatus capable of processing a workpiece without polishing unevenness by controlling the vibration of a spring during polishing. And

[Means for solving the problem]

The present invention relates to a polishing apparatus for polishing or grinding a workpiece, by pressing a supporting member of the tool via an elastic member by a pressing member that is interlocked with a servomotor to polish or grind the workpiece. A first means for detecting an operating angle (φa), a means for detecting a pressing pressure (F) of the supporting member against the tool, and a first-third factorial time differential coefficient of the operating angle (φa). Control of the servomotor by using a calculating means, a second calculating means for calculating a first-order to second-factorial time differential coefficient of the pressing pressure (F), and outputs from the first and second calculating means. A servo motor command value calculating means for calculating a signal is provided.

The present invention also provides a tool for polishing or grinding a workpiece,
In a polishing apparatus for polishing or grinding the workpiece by pressing a supporting member of the tool through an elastic member by a pressing member that is interlocked with a servomotor, a unit that detects an operating angle (φa) of the supporting member, and the servo. Means for detecting the operating angle (φm) of the motor, third computing means for computing the first to fourth factorial time differential coefficients of the operating angle (φa), and the first to second floors of the operating angle (φm) Provided with a fourth calculating means for calculating a factorial time differential coefficient and a servo motor command value calculating means for calculating a control signal of the servo motor by using outputs from the third and fourth calculating means. Is.

(Operation)

In the present invention, the impedance of the polishing tool with respect to the workpiece is set, and the polishing tool is operated in accordance with this impedance. That is, the impedance of the spring to the grinding tool is set in consideration of the dynamic characteristics of the spring, the torque input of the motor that realizes this impedance is obtained, and this is input to the servo motor as a command value of the motor to control the servo motor. . The servomotor operates so that the output from the motor shaft swings the tool support member via a speed reducer or the like to control the pressing force on the workpiece.

〔Example〕

FIG. 4 is a diagram showing a hardware configuration of the polishing apparatus according to the present invention.

An endless belt is wound around the servo motor 1, so that the rotation of the servo motor is transmitted to the pressing member 3. As a result, the pressing member 3 interlocks with the servomotor 1 and freely swings around the polishing apparatus body 2.
The pressing member 3 performs an operation of converting the operating angle φm of the servo motor 1 into the displacement of the pressing member.

One end of the spring 4 is attached to the end of the pressing member 3, and the other end of the spring 4 is attached to the end of the grinder support member 5. By this spring 4, the pressing member 3
The rocking pressure is transmitted to the grinder support member 5. Instead of the spring 4, it is possible to use an elastic member having low rigidity and partially including a spring element.

The grinder support member 5 is attached to one end of the spring 4 and freely swings around the polishing apparatus body 2. As a result, the load operating angle φa formed by the grinder 6 is formed, and the pressing pressure F applied to the spring 4 is transmitted to the grinder 6. The grinder 6 is supported by the grinder support member 5, and the spring 4
Grinding while pressing the workpiece 8 by the pressing force F of.

The grinder 6 is configured so that an endless polishing belt rotates about two axes to polish a workpiece. A potentiometer 7 for detecting an operation angle (load operation angle) φa of the grinder support member 5 is attached to the grinder support member 5. Further, in order to detect the external force F applied to the grinder 6 from the workpiece 8, a force sensor 9 is attached between the grinder support member 5 and the grinder 6.

FIG. 3 is a block diagram showing the configuration of the control portion of the polishing apparatus of the present invention. The output signal from the potentiometer 7 for detecting the operating angle (load operating angle) φa of the support member 5 of the grinder 6 and the output signal from the sensor 9 for detecting the external force F are passed through A / D converters 13a and 13b, respectively. Is converted into a digital signal and input to the CPU 15 through the input port 14. In CPU15, 1 for the time of operating angle φa of the support member
The third-order factorial differential coefficient and the first-second factorial differential coefficient of the external force F are calculated, and the motor torque input τm is calculated.

This motor torque input τm is output to D / via output port 16.
After being input to the A converter 14 and converted into an analog signal, a predetermined amplification is performed via an amplifier 18, and then the servo motor 1
Is output as a control signal.

FIG. 1 is a block diagram showing a detailed configuration of the CPU 15.
The first-third-order differential calculating means 19 inputs the operating angle φa from the potentiometer 7 and calculates the first-third-order differential coefficient with respect to time. In addition, the 1st and 2nd floor differential operation means 20 is a force sensor 9
The external force F from is input and the 1st to 2nd factorial differential coefficient with respect to time is calculated. The outputs of the calculating means 19, 20 are input to the servo motor command value calculating means 21, and the motor torque input τm is calculated by the following equation.

τm = Jm Rg / Kc (A (d ³ φa / dt ³ ) + (Kc + A) × (d ² φa / dt ² ) + (1 + A) (d ² F / dt ² )) + 1 / Rg (A (d φa / dt) + Aφa + (1 + A) F) (1) where Jm is the inertia moment of the servo motor 1 measured in advance, and Rj is the servo motor 1 measured in advance.
Reduction ratio, Kc is the stiffness coefficient of the spring 4 measured in advance,
t represents time. A is (-Jl / Md) and J
l and Md are the moment of inertia and the set mass of the support member and the tool that have been measured in advance. The motor torque input τm calculated according to the equation (1) is input to the servo motor 1 via the amplifier 18 as a motor command value. The output from the servo motor shaft oscillates the supporting member of the tool via a speed reducer or the like, and the pressing force on the workpiece is controlled.

 Next, formula (1) will be described in detail.

The present invention operates the polishing tool according to the set impedance by considering the dynamic characteristics of the spring. Therefore, it is now assumed that the impedance of the spring 4 with respect to the polishing tool 6 is set according to the following equation.

τs = −Jl / Md Kv (dφa / dt) −Jl / Md Kpφa + (1-Jl / Md) F (2) where τs is the torque input of the motor torque and Kv is the preset spring 5 The damping coefficient, Kp, is a stiffness coefficient of the spring 5, which is set in advance. If the dynamic characteristics of the system shown in FIG. 4 at this time are described, the following equation is obtained.

τs = Jl (d ² φa / dt ² ) + F (3) Therefore, from the equations (2) and (3), the impedance of the polishing tool 6 with respect to the workpiece 8 is as follows.

Md (d ² φa / dt ² ) + Kv (dφa / dt) + Kp φa + F = 0 (4) In this equation, any impedance can be set by appropriately setting Md, Kv, and Kp. Therefore, in order to realize the expression (4), the torque input τm of the motor that realizes the impedance of the expression (2) may be obtained. By the way, the following equation is established between τs and τm.

(ΤM−τs / Rg) / (Rg Jm S ² ) −φa = τs / Kc (5) where s is a Laplace operator.

By substituting equation (5) into equation (2),
You can get the formula. In this way, the polishing tool 6 can be operated according to the impedance set by the equation (4).

The method of the present invention is called an impedance control method, and generally, when there is a spring element between the motor and the load side, that is, the grinder side, an error occurs between the set impedance and the actual impedance, and the grinder follows the set impedance. However, in the present invention, the spring is operated in accordance with the command in consideration of the rigidity of the spring.

Although the external force F is detected by the force sensor 9 in order to calculate the motor command value in the above-described embodiment, the operating angle φm of the servo motor 1 may be used instead of the external force F for control.

The potentiometer 12 shown in FIG. 4 is a detecting means for detecting the operating angle φm of the servomotor 1. If the configuration of the CPU 15 is changed as shown in FIG.
The servo motor command value can be calculated in the same manner as in the case of FIG. The operating angle φm of the servomotor and the operating angle φa of the supporting member are respectively the first
It is input to the CPU 15 as in the case of the figure.

The CPU 15 calculates the amount Fc corresponding to the external force F defined by the following equation.

Fc = Kc (φm / Rg−φa) −Jl (d ² φa / dt ² ) ... (6) By inserting Fc obtained here into F of equation (1), the same as the case shown in FIG. Can be controlled. However, since the motor torque input τm is calculated according to the equations (1) and (6), the differential calculation means of the working angle φa of the support member requires differential calculation of the first to fourth factorials,
Further, the differential operation of the operating angle φm of the servo motor is 1 to
Second factorial calculation is required. For this purpose, the 1st to 4th order differential calculating means 22 and the 1st to 2nd order differential calculating means 23 shown in FIG. 2 are required in place of the calculating means 19 and 20 shown in FIG.

In the above-mentioned embodiments, the polishing apparatus using the spring for pressing is extended, but the present invention is applied to general systems in which the rigidity between the motor and the load is low, and that portion is equivalently a spring element. The method is effective.

〔The invention's effect〕

As described in detail with reference to the above embodiments, the present invention can effectively prevent uneven polishing of a polishing apparatus that performs control in consideration of vibration of a spring during polishing. Further, since it can be realized by an inexpensive CPU and a simple program without improving the main body of the apparatus, a low-cost polishing apparatus can be realized.

Further, when the means for detecting the pressing pressure of the support member is used, the number of calculation steps is reduced and the control response is improved. Further, when the means for detecting the operating angle of the servo motor is used, the detection error can be avoided as compared with the case where the force sensor is used, so that the control accuracy is improved, and the force sensor is unnecessary, so that the cost can be reduced. Control can be realized.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a control portion of a polishing apparatus according to an embodiment of the present invention, FIG. 2 is a block diagram showing a configuration of a control portion of another embodiment of the present invention, and FIG. FIG. 4 is a block diagram showing a schematic configuration of a control part of the present invention, FIG. 4 is a diagram showing a schematic configuration of a hardware part of a control device of the present invention, and FIG. 5 is a diagram showing a schematic configuration of a hardware part of a conventional device. . In the figure, 1 ... Servo motor, 2 ... Polishing device main body, 3 ... Pressing member, 4 ... Spring, 5 ... Grinder support member, 6 ... Grinder, 7 ... Potentiometer, 8 ... Workpiece, 9 ... Force sensor, 12 ... Potentiometer, 19 ... 1st to 3rd order differential calculating means, 20 ... 1st to 2nd order differential calculating means, 21 ... Motor command value calculating means, 22 ... 1
~ 4th floor differential operation means, 23 ... 1st to 2nd floor differential operation means.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP 62-218054 (JP, A) JP 61-257754 (JP, A) JP 64-50077 (JP, A) JP 1- 252340 (JP, A) Actually open 64-56953 (JP, U) Actually open 1-163058 (JP, U)

Claims (4)

(57) [Claims] 1. A polishing apparatus for polishing or grinding a workpiece by pressing a support member of the tool through an elastic member by a pressing member that is interlocked with a servomotor to polish or grind the workpiece. A means for detecting the operation angle (φa) of the member, a means for detecting the pressing pressure (F) of the support member against the tool, and a first-third factorial time differential coefficient of the operation angle (φa). A first calculating means; a second means for calculating a first-second factorial time differential coefficient of the pressing pressure (F); and the servomotor using outputs from the first and second calculating means. And a servo motor designated value calculating means for calculating the control signal of the polishing apparatus. 2. The polishing apparatus according to claim 1, wherein a motor torque input τm calculated by the following equation is used as the control signal. τm = Jm Rg / Kc (A (d ³ φa / dt ³ ) + (Kc + A) × (d ² φa / dt ² ) + (1 + A) (d ² F / dt ² )) + 1 / Rg (A (d φa / dt) + Aφa + (1 + A) F), A = -Jl / Md where Jm is the moment of inertia of the servo motor, Rg is the reduction ratio of the servo motor, Kc is the rigidity coefficient of the elastic member, and Jl is the support member. And the moment of inertia of the tool together, Md is the set mass of the support member, t is the time 3. A polishing apparatus for polishing or grinding a workpiece by pressing a supporting member of the tool through a resilient member by a pressing member that works in conjunction with a servomotor against the tool for polishing or grinding the workpiece. A means for detecting the operating angle (φa) of the member, a means for detecting the operating angle (φm) of the servo motor, and a third for calculating the first to fourth factorial time differential coefficients of the operating angle (φa). Arithmetic means, fourth arithmetic means for computing the first to second factorial time derivative of the operating angle (φm), and control of the servomotor using outputs from the third and fourth arithmetic means A polishing machine comprising: a servo motor command value calculating means for calculating a signal. 4. The polishing apparatus according to claim 3, wherein a motor torque input τm calculated by the following equation is used as the control signal. τm = Jm Rg / Kc (A (d ³ φa / dt ³ ) + (Kc + A) × (d ² φa / dt ² ) + (1 + A) (d ² F / dt ² )) + 1 / Rg (A (d φa / dt) + Aφa + (1 + A) F), A = −Jl / Md F = Kc (φm / Rg−φa) −Jl (d ² φa / dt ² ) where Jm is the moment of inertia of the servo motor and Rg is the above Reduction ratio of the servo motor, Kc is the rigidity coefficient of the elastic member, Jl is the moment of inertia of the support member and the tool combined, Md is the set mass of the support member and the tool combined, and t is the time.