JPH0632885B2 - Ceramic grinding method and device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a grinding method and apparatus used for mirror-finishing ceramics.

Conventional Technology Conventionally, for example, alumina (Al ₂ O ₃ ), silicon nitride (Si ₃
N ₄ ), zirconia (ZrO ₂ ), silicon carbide (SiC), and other high-density ceramics are mirror-finished by pressing a surface plate called a lap against the finished surface of the work piece, and lapping a fine-powder polishing agent between them. It is carried out by lapping or polishing to obtain a smooth finished surface by shaving very small chips from the surface of the work piece with a lap material by inserting them as a material and moving them relative to each other.

Problems to be Solved by the Invention By the way, since the above-mentioned lapping and polishing are polishing processes, only a processing speed of 1 to 2 μ / min can be desired, and there is a problem that the efficiency is very poor. Moreover, since it is a batch system, it is very difficult to control the thickness dimension of the work piece for each batch. Further, since the surface plate wears, it is necessary to correct and polish the surface plate from time to time to maintain accuracy, which makes automation difficult.

Therefore, the present invention is intended to perform mirror polishing of ceramics by grinding with a grindstone.

However, when the mirror-finishing of ceramics is performed by the same grinding method as metal grinding, the change in the grinding resistance is large with respect to the change in the sharpness of the grindstone, and the flatness also varies with the change in the grinding resistance. I knew by experiment. That is, when the alumina (Al ₂ O ₃ ) ceramics is mirror-finished by normal surface grinding in an experimental machine, the following results are obtained under the best conditions, and when several pieces are polished, chattering, burning, and chipping occur. Occurred. However, the experiment was conducted with the diameter of the alumina ceramics being 45 mm and the stock removal being 20 μm.

Surface roughness Ra0.4 Grinding time 30 minutes Flatness 1.5 μm The above results show that the conventional grinding method is mechanical forced cutting, so the grinding work is performed regardless of the sharpness of the grindstone and the grinding resistance is not constant. However, this takes a long time, and in most cases grinding is impossible, which is not practical for mirror-finishing ceramics.

Therefore, an object of the present invention is to provide a ceramic grinding method and apparatus capable of efficiently performing mirror finishing of ceramics with high precision.

Means for Solving the Problems In order to achieve the above object, the present invention provides (1) a method of grinding a ceramic by giving a cut to a rotationally driven grindstone by displacement of a piston of a cylinder, and By detecting the external force acting in the displacement direction with a pressure sensor and feedback-controlling the fluid supply pressure to the cylinder so that it always becomes the set pressure, a constant pressure cut is constantly given to the grindstone to grind the ceramic with constant pressure. A method of grinding ceramics characterized by the above.

(2) Pressurized pressure always becomes the set pressure by detecting the external force acting in the actual displacement direction of the piston with the pressure sensor and performing feedback control of the fluid supply pressure to the tube so that it always becomes the set pressure. A constant pressure cylinder configured as described above, a whetstone rotating spindle rotatably supported by a piston of the constant pressure cylinder, a whetstone driving motor that rotationally drives the whetstone rotating main spindle, and an end portion of the whetstone rotating main spindle. A grinding machine for ceramics, comprising a grindstone head composed of a grindstone mounted on the.

Is provided.

Action According to the present invention, since the actual external force of the piston is always controlled by the feedback control, the constant pressure cylinder is always provided with a constant pressure to give a constant pressure cut to the grindstone to grind the ceramics. The grinding resistance can be made constant regardless of the sharpness of the grindstone, which allows the ceramics to be ground smoothly and a smooth finished surface can be obtained. Is obtained.

EXAMPLES The present invention will be described below with reference to FIGS. 1 to 3.

In FIG. 1, (1) is a grindstone head supported so that the tilt can be adjusted to the front and back and the left and right of the column (2), and includes a constant pressure cylinder (3), a grindstone rotating spindle (4), a grindstone (5) and a grindstone. It is composed of a drive motor (6).

The constant pressure cylinder (3) has a piston (8) slidably inserted through a tube (7) attached to the column (2) so as to be tiltable back and forth and left and right, and a pressure is applied to the piston (8). A sensor (9) is provided in the vicinity of the pressure gas or pressure liquid such as compressed air or hydraulic pressure from the pressure generator (10) through the fluid supply circuit including the pipe (11) and the electromagnetic switching valve (12). By supplying to the tube (7), the piston (8) is moved back and forth or moved up and down, and the thrust of this piston (8) is detected by the pressure sensor (9) to the tube (7) by the pressure generator (10). By performing feedback control of the supply pressure of the pressure gas or the pressure liquid, the pressurizing pressure is always set to the set pressure. In addition, the thrust of the piston (8) mentioned here is
It is an external force acting in the actual displacement direction of the piston (8). The pressure sensor (9) is supported by a support bracket (not shown) on the outside of the column (2) or the tube (7) so as to face the dog (8a) attached and fixed to the lower end of the piston (8).
The thrust of the piston (8) is detected by measuring the pressure with which the piston (8) descends and the dog (8a) presses the tracing stylus (9a). And
The thrust force of the piston (8) detected by the pressure sensor (9) is input to a computer unit (not shown), the computer unit performs comparative calculation processing and sends a command to the pressure generator (10), and the pressure generator The pressure of the constant pressure cylinder (3) is constantly controlled by feedback controlling the supply pressure of the pressure gas or pressure liquid to the tube (7) so that the thrust of the piston (8) becomes the set pressure at (10). Set pressure.

The grindstone rotating spindle (4) is rotatably supported by a piston (8) of a constant pressure cylinder (3) through a rolling bearing or a hydrostatic bearing (not shown) so as to pass through the piston vertically. A passage (13) for grinding fluid is provided in the portion.

The grindstone (5) is a diamond grindstone with a grain size of # 1000 or more and a vitrified binder as a binder, and is detachably attached to the lower end of the grindstone rotary spindle (4). A circular hole in which a plurality of nozzle holes (14) are opened diagonally downward at positions equidistant from the inner circumference of the grindstone (5) that are in communication with the grinding fluid passage (13) of (4). (15) is drilled.

The grindstone drive motor (6) is integrally fixed to the constant pressure cylinder (3), and is fixed to the output shaft (16) of the pulley (17) and the grindstone rotating spindle (4) by a spline. The pulley (18) fitted and fixed is connected via the V-belt (19) to rotate the grindstone (5).

Reference numeral (20) is a table arranged below the grindstone head (1) so as to face it, and a chuck (21) is arranged therein.

The rotary shaft (22) of the chuck (21) is rotatably supported by the table (20) via a rolling bearing or a hydrostatic bearing (not shown), and a pulley (24) is driven by a work rotation drive motor (23). ), A V belt (25) and a pulley (26).

(27) is a workpiece whose surface is mirror-finished, and chuck (21)
It is held on the upper surface by a suitable means such as vacuum suction.

(28) is a sizing device and two in-process gauges (29)
(30) is provided, and the probe is brought into contact with the ground surface of the work (27) and the chuck surface of the chuck (21) to measure the surface position, and the work ( 27)
The thickness of the grindstone (5) is continuously measured during grinding, and the rotation speed and pressurizing pressure of the grindstone (5) are adjusted so that rough grinding, fine grinding, and sparkout can be performed depending on the thickness of the work (27). Control.

(31) is a coolant discharge nozzle which is arranged on the side opposite to the grinding position of the grindstone (5) of the grindstone head (1) so as to face the grinding surface of the grindstone (5), and has a high pressure of 70 kg / cm ² or more. Then, the coolant is discharged toward the grinding surface of the grindstone (5).

Next, the grinding method and apparatus of the present invention having the above-mentioned structure will be described.

First, the work (27) is attached to the chuck (21) of the table (20).
After vacuum suction and holding, the chuck (21) is driven by the work rotation drive motor (23) to the pulley (24),
The work (27) is rotated by being rotationally driven via the V-belt (25), the pulley (26) and the rotating shaft (22). Next, the grindstone (5) of the grindstone head (1) is driven by the grindstone driving motor (6) to a peripheral speed of 400 m through the pulley (17), the V belt (19), the pulley (18) and the grindstone rotating main shaft (4). / Rotate at above min. In this state, the grindstone head (1)
As shown in FIGS. 3 (A) and 3 (B), the constant pressure cylinder (3) moves the grindstone (5) up and down through the grindstone rotating spindle (4) or moves the work (27) by the grindstone (5). In, →
Grinding is performed in the grinding cycle of spark-out → return or rough grinding → fine grinding → return. The work (27) with the grindstone (5)
Immediately before grinding the grinding wheel, the grinding fluid passageway (13) of the grinding wheel spindle (4), the circular hole (15) of the grinding wheel (5) and the nozzle hole (14)
The grinding liquid is supplied to the workpiece through the above, and the high pressure coolant is discharged from the coolant discharge nozzle (31) toward the grinding surface of the grindstone (5).

Then, during grinding, the thrust of the piston (8) of the constant pressure cylinder (3) is pressured so that the grinding pressure of the grindstone (5) is constant with respect to the work (27) regardless of the sharpness of the grindstone (5). The tube (7) so that the thrust of the piston (8) detected by the sensor (9) and the output generator (10) reaches the set pressure.
By feedback-controlling the supply pressure of the pressure gas or the pressure liquid to the constant pressure cylinder (3), the pressure is constantly set so that the grindstone (5) is cut by the constant pressure cylinder (3). The work (27) is given and ground with a constant grinding pressure. At this time, the pressurizing pressure of the constant pressurizing cylinder (3) is variably controlled according to the rough polishing, the fine polishing, the spark out and the return as shown in FIG. Also, grindstone (5)
Also, the rotation speed of the work (27) is variably controlled according to the rough grinding, the fine grinding, the spark out, and the return, as shown in FIG. When the above grinding cycle ends, the work (2
After unloading 7) from the chuck (21), a new work (27) is loaded on the chuck (21) and thereafter the above grinding cycle is repeated to continuously grind the work (27). The grinding amount of the work (27) to be ground by cutting the grindstone (5) with the constant pressure cylinder (3) is slightly smaller than the measuring stroke of the contact point (9a) of the pressure sensor (9). Therefore, even if the grindstone (5) is fully cut by the constant pressure cylinder (3), it does not affect the measurement of the thrust of the piston (8) by the pressure sensor (9).

According to the above grinding method and device, the grinding pressure of the grindstone (5) is constant with respect to the work (27) regardless of the sharpness of the grindstone (5). Therefore, the work (27) is smoothed by the grindstone (5). It can be mirror-finished and a smooth finished surface can be obtained. Moreover, since the grinding resistance is constant, high flatness can be obtained. This has been verified by experiments. That is,
In the experiment, the following results were obtained when the alumina (Al ₂ O ₃ ) ceramics were mirror-finished by the surface grinding by the above-mentioned grinding method in the experimental machine. However, the experiment was conducted with the diameter of the alumina ceramics being 45 mm and the stock removal being 20 μm.

Surface roughness Ra 0.015 Grinding time 12 seconds Flatness 0.3 μm As a result, the target surface roughness Ra 0.02 and grinding time
The flatness of 0.5 μm is satisfied for 15 seconds.

In the grinding apparatus of the above-described embodiment, since the grindstone head (1) is provided on the column (2) so that the tilt can be adjusted in the front-rear and left-right directions, the work (27) can be mirror-ground to the convex surface and the concave surface. is there. Further, the grinding liquid nozzle hole (14) connected to the grinding liquid passage (13) provided in the shaft core portion of the grindstone rotating main shaft (4) of the grindstone head (1) is located slightly inside the inner diameter of the grinding surface of the grindstone (5). Since it is provided, the grinding liquid can be efficiently supplied to the work (27). Further, since a nozzle (31) for discharging a high pressure coolant is provided facing the grinding surface of the grindstone (5), the cooling property is improved, the machinability is improved, the grindstone life is improved, and the grindstone is prevented from clogging. The coolant effect can be obtained.

EFFECTS OF THE INVENTION As described above, according to the grinding method and the grinding apparatus of the present invention, when grinding ceramics, the constant external pressure force of the piston causes the actual external force of the piston to always become the set pressure by the constant pressure cylinder. Since the notch is given to the grindstone to always grind the ceramic with a constant pressure, the grinding resistance is constant regardless of the sharpness of the grindstone, and the mirror surface machining of the ceramic can be efficiently and highly accurately performed. Automation is also easy.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a ceramic grinding method and device according to the present invention, FIG. 2 is a sectional view of a grindstone, and FIG.
FIG. 6 is a diagram showing the relationship between the normal grinding cycle, the pressure applied, the rotational speed of the grindstone, and the work. (1) …… Grinding wheel head, (3) …… Constant pressure cylinder, (4) …… Grinding wheel rotating spindle, (5) …… Grinding wheel, (6) …… Grinding wheel drive motor, (9) …… Pressure sensor , (20) …… table, (21) …… chuck, (23) …… work drive motor, (27) …… work, (28) …… sizing device, (31) …… coolant discharge nozzle.

Claims (2)

[Claims] 1. A method for grinding ceramics by making a cut in a rotationally driven grindstone by displacement of a piston of a cylinder, wherein an external force acting in an actual displacement direction of the piston of the cylinder is detected by a pressure sensor and is always set. A method of grinding ceramics, characterized in that the grinding fluid is constantly subjected to constant pressure cutting by performing feedback control of the fluid supply pressure to the cylinder so that the pressure becomes equal to the pressure, so that the ceramics is ground under constant pressure. 2. The pressurizing pressure is constantly set by detecting the external force acting in the actual displacement direction of the piston with a pressure sensor and feedback-controlling the supply pressure of the fluid to the tube so that it always becomes the set pressure. Of the constant pressure cylinder, a grindstone rotary spindle rotatably supported by a piston of the constant pressure cylinder, a grindstone drive motor for rotationally driving the grindstone rotary spindle, and the grindstone rotary spindle. A ceramics grinding apparatus comprising a grindstone head including a grindstone attached to an end portion.