JP2552537B2 - Control method for grinding machine equipped with spindle device with bending detection means - Google Patents

Description

TECHNICAL FIELD The present invention relates to a control method for a grinding apparatus equipped with a spindle device with a deflection detecting means.

[Outline of Invention]

The present invention, in a grinding machine equipped with a spindle device with a bending detection means, controls the grinding processing conditions by the amount of bending of the grinding wheel axis in the direction of the grinding wheel axis normal detected by the spindle device with a bending detection means, processing accuracy, processing It aims to improve efficiency.

[Prior Art] In the conventional grinding apparatus, since the processing steps such as rough grinding, fine grinding, and finish grinding are uniformly determined by the dimensional change of the work, only the cutting switching point is set.

There is also a grinder such as the one disclosed in JP-B-53-34676, in which the cutting is controlled based on the grinding power consumed by the grindstone shaft. This indirectly detects the grinding resistance in the tangential direction of the grindstone axis (direction perpendicular to the cutting direction), and thereby controls the cutting switching point and the cutting speed.

[Problems to be Solved by the Invention]

However, in the former case, it is not possible to process the work under optimal cutting conditions in a timely manner that also considers the sharpness of the grindstone, and therefore the processing accuracy and processing efficiency such as roundness, cylindricity, and surface roughness are constant. There is a problem that it cannot be improved beyond the limit.

In the latter case, although it is said that it is most preferable to detect the grinding resistance in the grindstone axis normal direction (cutting direction) in judging the sharpness of the grindstone, the grinding resistance in the tangential direction Since it is detected, the difference in sharpness of the grindstone cannot be sufficiently detected, and there is a problem that it is difficult to control to the optimum processing conditions.

[Means for solving the problem]

Therefore, a method of controlling a grinding apparatus including a spindle device with a deflection detecting means according to the present invention, in order to solve the above problems, a grindstone shaft provided with a grindstone at the tip portion, and a normal direction of the grindstone with respect to the work and In a machining control method for determining a tool correction time of a grinding machine equipped with a spindle device equipped with a flexure detecting means for detecting a flexure amount of a tip portion of a grindstone shaft due to a grinding resistance load in a tangential direction, a spark in grinding is provided. By measuring the change in the flexure amount at the time of out based on the signal value of the flexure detection means, the sharpness of the grindstone is evaluated, the adjustment of the processing conditions and the tool correction (dressing) timing are determined. Is.

[Action]

According to the control method of the grinding apparatus including the spindle device with the bending detecting means, the bending of the tip portion of the grindstone shaft due to the processing load in the normal direction (cutting direction) of the grindstone with respect to the work detected by the bending detecting means Since the machining conditions are adjusted based on the amount, the sharpness of the grindstone can be accurately determined, and the machining of the work under optimal machining conditions in a timely manner that also considers the sharpness is realized, and the machining accuracy and The processing efficiency can be improved.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. 1 to 3 are diagrams showing an embodiment of a control method of a grinding apparatus provided with a spindle device with a deflection detecting means according to the present invention.

FIG. 4 and FIG. 5 are views showing a spindle device with a deflection detecting means applied to the present invention. In FIG. 4, a high frequency motor 10 is provided at the middle of the spindle device 5 in the longitudinal direction.
Is provided. The high frequency motor 10 has a rotor 8 having a shaft hole 8a formed inwardly of its radius.
A grindstone shaft 12 having a grindstone 11 for grinding a work W at a tip portion 12a (the left end portion in the figure) is rigidly fitted to 8a and integrally rotatable.

The high frequency motor 10 is held in a casing 14 that forms the outer shape of the spindle device 5, and both ends of the grindstone shaft 12 are supported by bearings 13a and 13b at both ends of the casing 14. Further, a sensor holder 21 is provided on the workpiece W side of the casing 14, and sensors 16 to 19 (deflection detecting means) are arranged on the grindstone shaft 12 side of the sensor holder 21 as shown in FIG. There is. Each of the sensors 16 to 19 detects the gap between the peripheral surface of the cylindrical target 15 fixed to the outer periphery of the tip portion 12a of the grindstone shaft 12, and the radial direction of the tip portion 12a of the grindstone shaft 12, In particular, the amount of bending in the normal direction (the cutting direction of the grindstone 11, that is, the X direction in FIG. 5) and the tangential direction is detected.

Further, a shielding member 20 formed of a heat insulating material such as bakelite is provided on the work W side of the sensor holder 21 so that the grinding liquid from the work W side does not directly contact the sensors 16 to 19 and the sensor holder 21. The detection function is not significantly impaired.

Each of the sensors 16 to 19 has a structure in which a copper wire coil is wound around an iron core, and detects the inductance that changes as the gap between the end of the iron core and the peripheral surface of the target 15 changes. Then, the bending amount (displacement amount) in the radial direction of the tip portion 12a of the grindstone shaft 12 is detected.

In the spindle device 5 as described above, the high-frequency motor 10 drives the grindstone shaft 12 to rotate at a high speed, so that the grindstone 11
Grinds the inner surface of the work W. At this time, the sensors 16-19
Detects the amount of bending of the tip portion 12a of the grindstone shaft 12 due to the grinding resistance load, and controls the cutting speed and the cutting amount based on the amount of bending of the grindstone shaft 12, or determines the appropriate timing for tool correction (dressing). By setting it, the work can be processed under the optimum processing conditions in a timely manner.

That is, referring to FIG. 1 to FIG. 3, first, the control block diagram of FIG. 3 will be described. The deflection amount of the tip of the grindstone shaft is detected by a detection sensor, and the detection signal and the signal of the sizing device are sent to the main controller. The servo motor is driven and controlled by the control unit of the main controller, the X-axis cutting controller, the servo driver, and the encoder, and the cutting of the grindstone is controlled.

Next, each grinding step will be described with reference to FIGS. 1 and 2.

The grindstone shaft 12 is driven to rotate by a high frequency motor,
11 is also rotated, and the grindstone 11 is fed from the state where it does not come into contact with the work W at the cutting speed V _GR , which is the rough grinding gap cutting speed. When the grindstone 11 and the workpiece W come into contact with each other and are further cut and fed, the tip portion 12a of the grindstone shaft 12 starts to bend.
The amount of flexure of the grindstone shaft, that is, the amount of flexure δ of the tip portion 12a of the grindstone shaft 12 in the normal direction (cutting direction) is detected by the sensors 16 and 18. The detection signal of the deflection amount δ is sent to the main controller through the grindstone shaft deflection amount detection amplifier, and the deflection amount δ
Becomes δ _GR , the roughing gap cutting speed V _GR is controlled and switched by the X-axis cutting controller, the servo driver, the servomotor, and the encoder so that the roughing grinding cutting speed V _GR becomes the initial rough cutting cutting speed V _RI .

The rough-cutting cutting speed V _R after switching to the initial rough-cutting cutting speed V _RI is controlled so that the deflection amount δ in the normal direction of the tip portion 12a of the grindstone shaft 12 is constant at Δ _GR . Therefore, the rough grinding cutting speed V _R is not constant.

When the work W reaches the first predetermined size, the first sizing signal is output from the sizing device that detects the dimensional change of the work W during grinding, and is input to the main controller through the sizing amplifier, and the rough cutting is stopped. After that, we will enter the Koken Spark Out.

The rough-polish spark-out time T _{R at} this time ends when the deflection amount Δ in the normal direction of the tip portion 12a of the grindstone shaft 12 returns to Δ _RSP .

Next, when the amount of deflection returns to δ _RSP , retraction is performed to temporarily retract the notch of the grindstone 11, and once the grindstone 11 is separated from the work W, the polishing gap notch speed V _GF
The grindstone 11 is cut and fed by, and the grindstone 11 and the work W contact again, and when further cut and fed, the tip portion 12a of the grindstone shaft 12 is
Begins to bend.

The deflection amount δ in the normal direction is detected by the sensors 16 and 18, and the detection signal is input to the main controller. When the deflection amount δ becomes δ _f , this signal causes the initial speed of the precision cutting gap cutting speed V _{GF to} be the initial value. The precision cutting speed V _FI can be switched.

The fine-cutting cutting speed V _F after switching to the initial fine-cutting cutting speed V _FI is controlled so that the bending amount δ in the normal direction of the tip portion 12a of the grindstone shaft 12 is constant at δ _f . Therefore, the precision cutting speed V _F is not constant.

When the workpiece W reaches the second predetermined dimension, the second sizing signal is output from the sizing device and is input to the main controller through the sizing amplifier.

The _Seiken spark-out time T _{fsp at} this time is 12
On the basis of the time T _F required for the deflection amount δ of the tip end portion 12a of the front end 12a in the normal direction to return from δ _f to δ _fsp , for example, (δ _f −
Calculated from δ _fsp ) / T _F.

After T _fsp time has passed, the polishing process is completed and the grindstone 11 is the work W.
Be separated from.

Further, after the start of the Seiken spark-out, the time T _F until the deflection amount δ detected by the sensors 16 and 18 returns from δ _f to δ _fsp is measured by the control unit, and the time T _F is the judgment of the sharpness of the grindstone. When the value exceeds the predetermined value, the dressing instruction command is issued as if the sharpness of the grindstone deteriorates.

In this way, based on the deflection amount of the grindstone shaft 12 in the normal direction, by controlling the cutting speed and the cutting amount, or by outputting a tool correction instruction, the sharpness of the grinding stone 11 is always maintained in a good state. By doing so, it is possible to realize the processing of the work W under the optimum processing conditions, and to improve the processing accuracy and processing efficiency.

In the above embodiment, the normal direction sensors 16 and 18 detect and control the deflection amount δ with the X direction in FIG. 5 as the cutting direction, but when the Y direction is the cutting direction, the sensor is used.
The amount of bending may be detected by 17, 19 and control driven by the Y-axis motor.

〔The invention's effect〕

According to this invention, based on the amount of bending of the grindstone shaft detected during cutting of the whetstone in the grinding process, the cutting of the whetstone is controlled, or the whetstone is based on the change in the detected amount of bending during spark-out. By determining the sharpness, the grinding process under the optimum processing conditions is realized, and the processing accuracy and the processing efficiency can be improved.

[Brief description of drawings]

FIG. 1 shows the cutting movement amount of the grindstone in the embodiment of the present invention.
FIG. 2 is a diagram for explaining the relationship between the deflection of the grindstone shaft and the elapsed time, FIG. 2 is a control flow chart diagram in the embodiment of the present invention, and FIG. 3 is a control block diagram of an apparatus applied to the embodiment of the present invention.
FIG. 4 is a spindle device diagram in a device applied to an embodiment of the present invention, and FIG. 5 is a sectional view taken along the line II-II in FIG. 5 …… Spindle device 8 …… Rotor 8a …… Shaft hole 10 …… High frequency motor 11 …… Grinding stone 12 …… Grinding stone shaft 12a …… Tip 13a, 13b …… Bearing 14 …… Casing 15 …… Target 16 to 19 …… Sensor (deflection detection means) 20 …… Shielding member 21 …… Sensor holder

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-59-69245 (JP, A) JP-A-63-295176 (JP, A) JP-A-63-295177 (JP, A) Actual development Sho-61- 181660 (JP, U)

Claims (2)

(57) [Claims] 1. A control of a grinding machine for detecting a change in the amount of bending of a grindstone shaft and controlling a cutting speed and a cutting amount in accordance with the detected amount to execute a cutting process consisting of rough grinding and fine grinding. In the method, the polishing comprises a grinding step of controlling the cutting speed so that the amount of bending is constant and cutting until a predetermined dimension is reached, and a sparkout step following this, and during the polishing sparkout step. The time required for the amount of bending to reach a predetermined amount of bending from the amount of bending at the end of the grinding step is measured, the sharpness of the grindstone is evaluated from this measured value, and the tool correction time is determined. A method for controlling a grinding machine equipped with a spindle device with a deflection detecting means. 2. The spark-out time is known by detecting a change in the amount of flexure within that time in addition to the time required to reach the predetermined amount of flexure, and performing a calculation based on both values. A method for controlling a grinding apparatus provided with the spindle device with the deflection detecting means according to Item 1.