JPH09262757A - Method and device for surface finishing of ceramics - Google Patents

Abstract

PROBLEM TO BE SOLVED: To firstly provide a much smoothly polished surface by polishing a work with abrasive particles of higher hardness than that of the work to greatly shorten the machining time, and secondly polishing the work by abrasive particles of lower hardness than that of the work in the same process. SOLUTION: A work is firstly polished with first abrasive particles 19b of higher hardness than that of the work in polishing a surface of a ceramic, the work is secondly polished with the abrasive particles in which second abrasive particles 19a of lower hardness than that of the work are mixed in the first abrasive grains, the ratio of the second abrasive particles 19b is increased in the subsequent stages, and the work is finally polished with the second abrasive powders 19b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improvement of ceramic surface processing technology.

[0002]

2. Description of the Related Art A lapping method is one of surface polishing methods for ceramic parts. The lapping method supplies a lapping liquid, which is a mixture of abrasive grains such as diamond, to a liquid between the work piece and the tool (lap or polisher), and relatively and while applying pressure to the work piece and the tool. This is a processing method that causes a forced sliding motion. Since hard diamond is used as the abrasive grains, craters and streaky minute scratches remain on the polished surface. In the case of ceramic parts, there arises an inconvenience that the damage acts as a starting point of fracture and reduces the strength of the product.

As a countermeasure technique, for example, Japanese Patent Publication No. 56-
No. 23746, “High-precision mirror-polishing method for crystal material with soft particles” is proposed. This technique supplies particles that are softer than the work piece to the work piece surface as abrasive grains, and causes a solid-phase reaction between the particles and the work piece to occur due to frictional force. It is characterized in that a highly accurate mirror surface is obtained by removing the reaction portion of from the surface of the workpiece by frictional force.

[0004]

The conventional lapping method and the Japanese Patent Publication No. 56-23746 also require a lapping machine or a processing machine corresponding to the lapping method, which is used while applying pressure to the workpiece and the tool. Moreover, it is still a processing method in which forced sliding motion is performed. Since the amount of movement associated with this relative and forcible sliding motion is significantly larger than the diameter of the abrasive grains, surface scratches cannot be avoided. Surface scratches cause various problems such as a reduction in fracture strength and fatigue strength, a reduction in sliding characteristics, and an increase in opponent attack. Further, particularly when diamond abrasive grains are used, the abrasive grains are expensive and the processing cost increases.

Therefore, an object of the present invention is to provide a technique for easily and favorably polishing ceramics, which is a difficult-to-machine material, and a low-cost machining technique.

[0006]

In the process of studying the surface processing of ceramic parts, the inventors of the present invention minimize the relative slip amount between the workpiece and the tool in order to suppress the occurrence of surface scratches. Was found to be effective, and in order to obtain a smooth surface, an abrasive grain that is softer than the work piece should be adopted, and as a result of further research, we succeeded in establishing a technology that can achieve the purpose. .

Specifically, according to claim 1, when polishing the surface of ceramics, first, the hardness of the first is higher than that of the workpiece.
Polishing the work piece with the abrasive grains, and then polishing with the abrasive grains obtained by mixing the abrasive grains with the second abrasive grain having a hardness lower than that of the work piece.
After that, the ratio of the second abrasive grains is increased stepwise, and finally the workpiece is polished with the second abrasive grains. Since the work piece is first polished with a higher hardness than the work piece, the processing time is greatly shortened.Finally, the work piece is polished with a lower hardness than the work piece. As a result, a very smooth processed surface can be obtained.

According to a second aspect of the present invention, a side surface of a ceramic workpiece is sandwiched between a pair of plates, the plates are vibrated to rotate the workpiece, and a liquid containing abrasive grains around the workpiece. In the ceramic surface processing method of polishing the side surface of the work piece with the abrasive grains interposed between the vibrating plate and the side surface of the work piece to rotate, A work piece is polished with a first abrasive grain, and then a second abrasive grain having a hardness lower than that of the work piece is mixed with this abrasive grain, and then a second abrasive is gradually added. The method for surface processing of ceramics is characterized by increasing the ratio of the abrasive grains and finally polishing the work piece with the second abrasive grains.

Since the object to be processed is rotated while being rotated by vibrating it, a headstock and a motor for rotating the work are not required, so that the entire apparatus is simplified.
Further, since the side surface of the work piece is polished by the abrasive grains interposed between the vibrating plate and the side surface of the work piece that rotates, the relative slip amount between the work piece and the tool (vibrating plate) can be minimized. It is possible to obtain a very good surface without worrying about scratching the surface of the work piece.

According to a third aspect of the present invention, the ceramic is silicon nitride, the first abrasive grains are aluminum oxide, and the second abrasive grains are chromium oxide. Hard aluminum oxide can reduce the processing time. Further, a very smooth processed surface can be obtained by the partial solid phase reaction of aluminum oxide and the solid phase reaction of chromium oxide. Therefore, a very smooth processed surface can be processed in a short time. The reason why aluminum oxide is used as the first abrasive grain is that the abrasive grain causes a solid phase reaction with silicon nitride, which is a work material, and has a higher hardness than the work material, so that it is brittle (abrasive wear). Due to what happens. Also,
Since the solid-phase reaction causes the abrasive grains to react in the polishing step and gradually disappear, it is possible to perform continuous processing without the need to wash each step. If this is a diamond abrasive grain, it will remain until the end because the abrasive grain will not disappear, and finally a super smooth surface cannot be obtained.

According to a fourth aspect of the present invention, there are provided a pair of plates sandwiching a side surface of the ceramic workpiece, a vibrator for vibrating these plates to rotate the workpiece, and a side surface and the plate of the workpiece. Between the first abrasive grain having a hardness higher than that of the workpiece and the second abrasive grain having a hardness lower than that of the workpiece at a predetermined ratio. A ceramic surface processing apparatus is constituted by the processing liquid supply means for supplying the two abrasive grains.

Since the work piece is rotated and processed by the vibrator, a headstock and a motor for rotating the work piece are not required, so that the entire apparatus is simplified. Also,
Mixed abrasive grains formed by mixing a first abrasive grain having a hardness higher than that of the workpiece and a second abrasive grain having a hardness lower than that of the workpiece at a predetermined ratio, or the first abrasive grain or the second abrasive grain. Since the processing liquid supply means for supplying the abrasive grains is provided, the processing efficiency is high and an extremely good surface can be obtained in a short time.

[0013]

Embodiments of the present invention will be described below with reference to the accompanying drawings. The drawings should be viewed in the direction of reference numerals. FIG. 1 is an exploded perspective view of a ceramic surface processing apparatus of the present invention. Ceramic surface processing equipment 1
(Hereinafter, abbreviated as “surface processing apparatus 1”), for example, the fixed wall 3 and the movable wall 4 are arranged in parallel to the base 2,
A rubber plate 5 is attached to the inner surface of the fixed wall 3, and the rubber plate 5
The film 6 is attached to the inner surface of the vibrator 7, the vibrator 7 is attached to the inner surface of the movable wall 4, the rubber plate 8 is attached to the inner surface of the vibrator 7, and the film is attached to the inner surface of the rubber plate 8. 9
, And the ceramic work piece 10 ...
(... indicates a plurality of pieces; the same applies hereinafter). The films 6 and 9 are smooth members for promoting natural rotation of the workpieces 10 ...

Reference numeral 11 denotes a retainer, which is a workpiece 10 ...
It is a member that suppresses a certain amount of movement in the axial and radial directions. 13 are rods extending horizontally from the fixed wall 4, and the retainer can be fixed to the rods 13 ... with screws 14 ..., and the movable wall 4 can be fixed with screws 15 ... .
Reference numeral 16 denotes a mixed abrasive grain formed by mixing a first abrasive grain having a hardness higher than that of the workpiece and a second abrasive grain having a hardness lower than that of the workpiece at a predetermined ratio, or the first abrasive grain or the first abrasive grain. Machining fluid supply means for supplying the second abrasive grains, and the machining fluid supply means 16 includes a machining solution container 16a that stores a machining fluid containing the first abrasive particles, and a second machining solution container 16a.
Machining solution container 16b that stores machining fluid containing abrasive grains, machining fluid supply pipe 17, valve 18a that controls the discharge rate from machining solution vessel 16a, and valve that controls the discharge rate from machining solution vessel 16b. 18b. The working liquid supply pipe 17 is a member for dropping the working liquid onto the workpieces 10 ... While moving by a moving means (not shown).

FIG. 2 is a plan cross-sectional view of the ceramic surface processing apparatus of the present invention, which is a view corresponding to the assembly completion diagram of FIG. 1, but the film 6 because the rubber plates 5 and 8 are elastic bodies. , 9 can be satisfactorily applied to the workpiece 10. The oscillator 7 has a gear and an obstacle built therein, and when air is supplied from the outside, the gear rotates, and the convex portion of the gear collides with the obstacle, thereby generating a vibration having a relatively low frequency.

The operation of the surface processing machine 1 having the above structure will be described below. FIG. 3 is a principle view of surface processing according to the present invention. A side surface of a ceramic work piece 10 is sandwiched by a pair of rubber plates 5 and 8 with a film, and these rubber plates 5 and 8 are vibrated by a vibrator 7. At the same time, a working fluid containing abrasive grains 19a ..., 19b ... Is supplied to the periphery of the workpiece 10, and the abrasive grains 19a are interposed between the vibrating rubber plates 5 and 8 and the side surface of the workpiece 10 that rotates. , 19b ... Polish the side surface of the workpiece 10. Since the abrasive grains in the working fluid disappear due to the reaction, it is necessary to constantly supply an appropriate amount of abrasive grains. First, the abrasive grains 19a having a hardness higher than that of the workpiece 10 are supplied from the machining liquid container 16a, and thereafter, the abrasive grains 19b having a hardness lower than that of the workpiece 10 are gradually supplied from the machining liquid container 16b. Then, the high- and low-hardness abrasive grains 19a and 19b are mixed, and finally, only the abrasive grains 19b having a lower hardness than the workpiece 10 are supplied from the machining liquid container 16b.

[0017]

[Table 1]

As shown in Table 1 above, aluminum oxide (Al ₂ O ₃ ) has a Mohs hardness of 9 and silicon nitride (Si ₃
N ₄ ) has a Mohs hardness of 8 and chromium oxide (Cr ₂ O ₃ ) has a Mohs hardness of 7.

At this time, the workpiece 10 rotates at a constant speed (the rotation direction may be opposite to the arrow in the figure). Therefore, it is not necessary to forcibly rotate the workpiece 10. That is, in the conventional machining method, the work is forcibly rotated using the headstock and the motor as drive sources, but the present invention does not require the headstock or the motor.

Although processing a high-hardness work with the low-hardness abrasive grains 19b is contrary to the common sense of processing at first glance,
Machining proceeds because a solid-phase reaction occurs between the soft abrasive grains and the hard work. This technique is called a mechanochemical polishing (MCP) method, and it can be said that this technique is a chemical processing method when compared with a conventional mechanical processing method.

FIG. 4 is a diagram showing the proportion of abrasive grains supplied by the ceramic surface processing apparatus according to the present invention. First, aluminum oxide having a hardness higher than that of the workpiece is supplied, and thereafter,
The ratio of chromium oxide having a hardness lower than that of the workpiece is increased stepwise and supplied, and finally only chromium oxide is supplied.

FIG. 5 is another embodiment of the ceramic surface processing apparatus according to the present invention. The surface processing apparatus 20 includes a container 22 placed on a table 21 and a vibration tank 23 housed in the container 22.
A vibrator 24 attached to the bottom of the vibrating tank 23, and insulators 25, 25 for preventing transmission of vibration,
The fixed wall 26 housed in the vibrating tank 23 and the fixed wall 2
A rubber plate 27 and a film 28 attached to the upper surface of 6,
A retainer 29, a movable wall 33 having a film 31 and a rubber plate 32, and a weight 34 placed on the movable wall 33.
And rods 35, 35 erected from the fixed wall 26,
Screws 36, 36 for fixing the retainer 29 to the rods 35, 35, and the machining liquid 3 filled in the vibration tank 23.
7 The vibrator 24 is preferably a piezoelectric ceramic that is distorted by energization.

The working liquid 37 is a liquid containing oxide abrasive grains. Further, 38, 38 are heaters, and the machining liquid 37
This is a member for heating to a suitable temperature. Further, 39, 39 are weight stop pins.

For example, five workpieces 10 ... Are sandwiched between the rubber plates 27 and 32 with films from above and below, and the retainer 2 is used.
At 9, the movement in the left-right and axial directions is restricted. When the vibrator 24 is energized in this state, the vibrator 24 is 1000 to 10
The vibrating tank 23 is vibrated at a high frequency of 10,000 Hz. Then, the rubber plates 27 and 32 with a film vibrate in synchronism with each other, and as in the case of FIG. 3, the abrasive particles entered between the object 10 ... 10 ... is polished. Since the processing of the present invention is a kind of chemical processing method, the reaction rate can be increased by heating the processing liquid 37 to an appropriate temperature with the heaters 38, 38.
Further, since the working fluid 37 is vibrated, the abrasive grains are appropriately stirred and the deteriorated abrasive grains are replaced with new abrasive grains, so that the polishing efficiency is further increased.

FIG. 6 is a processing line layout diagram in which the ceramic surface processing apparatus of the present invention shown in FIG. 5 is arranged.
The hardness ratio of the abrasive grains of the working liquid 37 used in each step is changed. 37a, 37b, 37c, 37d, 37
e represents a working fluid used in steps 1 to 3. In the apparatus shown in FIG. 5, the working liquid 37 (37a to 37b) deteriorates with the chemical reaction, so it is necessary to continuously replenish the new liquid. In the process, polishing is performed with aluminum oxide having a hardness higher than that of the work piece, and in steps 1 to 3, the proportion of chromium oxide having a hardness lower than that of the work piece is gradually increased in the aluminum oxide, and in the process, polishing is performed with chromium oxide. To do. A predetermined surface roughness is obtained by sequentially polishing for a certain period of time in these steps to.

FIG. 7 is a diagram showing the proportion of abrasive grains used in each step of the processing line shown in FIG. 6, in which aluminum oxide having a hardness higher than that of the workpiece is 100%.
Then, the proportion of chromium oxide having a hardness lower than that of the workpiece is gradually increased in aluminum oxide. In the process, chromium oxide is 100%.

[0027]

Embodiments of the present invention will be described below. Examples 1-3; workpiece; shape; cylindrical size; 3.5 mm in diameter × 11 mm length material: silicon nitride (Si ₃ N ₄₎ surface roughness; 2～3S the workpiece in the pretreatment step, the Use the one that has been roughened.

Conditions of Example 1; machining fluid; composition; water + abrasive grains + surfactant abrasive grains; aluminum oxide (Al ₂ O ₃ ) frequency; 16,000 Hz

Conditions of Example 2; machining fluid; composition; water + abrasive grains + surfactant abrasive grains; chromium oxide (Cr ₂ O ₃ ) frequency: 16,000 Hz

Conditions of Example 3; processing liquid; composition; water + abrasive grains + surfactant abrasive grains; aluminum oxide (Al ₂ O ₃ ), chromium oxide (C
r ₂ O ₃ ) First, aluminum oxide having a hardness higher than that of the workpiece was supplied, and thereafter, chromium oxide having a hardness lower than that of the workpiece was gradually increased to finally obtain chromium oxide. Frequency: 16,000Hz

[0031]

[Table 2]

As shown in Table 1 above, the polishing rate of Example 1 was 72.5 × 10 ^-3 μm / min, and the processing efficiency was good, but the finished surface roughness of 0.01 could not be achieved. The polishing rate in Example 2 was 43.2 × 10 ⁻³ μm / min, and the finished surface roughness was good, but the processing efficiency was poor. The polishing rate in Example 3 was 60.5 × 10 ⁻³ μm / mi.
n, the finished surface roughness was the same as that of Example 2, and the processing efficiency could be dramatically improved.

From the above, according to the present invention, first, the work piece is polished with abrasive grains having a hardness higher than that of the work piece, and then the abrasive grains having a hardness lower than that of the work piece are mixed. , After that, the ceramic surface processing method in which the proportion of abrasive grains having a hardness lower than that of the workpiece is increased stepwise and finally the workpiece is polished with the abrasive grains having a hardness lower than that of the workpiece is extremely high. It was confirmed to be useful. Note that if it is harder than the work piece, it is a hard abrasive grain, and if it is soft, it is a soft abrasive grain, and aluminum oxide (Al ₂ O ₃ ) is silicon nitride (Si ₃ N ₄ ) that is the work piece.
Harder than mechanochemical polishing (M
CP) effect and brittleness processing effect are exhibited. Therefore, other abrasive grains may be used as long as they are such abrasive grains. Further, although two types of abrasive grains are used in this embodiment, the number of abrasive grains is not limited to two types, and three or more types of abrasive grains may be combined. In particular, it is possible to provide a processing line in which the steps of the processing line shown in FIG. 7 are exclusively used for diamond abrasive grains and rough machining with diamond abrasive grains is also included.

Furthermore, the low-hardness abrasive grains may be oxides having a lower hardness than the work piece. The following (chemical formula) is a reference example and is not limited to the substance of the chemical formula. For example, when the work piece is silicon nitride (Si ₃ N ₄ ), titanium oxide (TiO, Ti
O ₂ ), chromium oxide (Cr ₂ O ₃ ), iron oxide (Fe ₂
O ₃ , Fe ₃ O _4, ), silicon oxide (SiO ₂ ), cerium oxide (CeO ₂ ), barium carbonate (BaCO ₃ ),
At least one of calcium carbonate (CaCO ₃ ), magnesium oxide (MgO) and indium oxide (In ₂ O ₃ ) is used.

When the work piece is silicon carbide (SiC), titanium oxide (TiO, TiO ₂ ), chromium oxide (Cr ₂ O ₃ ), iron-based oxide (Fe ₂ O ₃ , Fe ₃ O ₄ ). , Silicon oxide (SiO ₂ ), cerium oxide (CeO ₂ ),
At least one of barium carbonate (BaCO ₃ ), calcium carbonate (CaCO ₃ ), magnesium oxide (MgO) or indium oxide (In ₂ O ₃ ).

When the work piece is alumina (Al ₂ O ₃ ), titanium oxide (TiO, TiO ₂ ), silicon oxide (SiO ₂ ), iron-based oxide (Fe ₂ O ₃ , Fe ₃ O ₄ ). Alternatively, at least one of magnesium oxide (MgO) may be used.

[0037]

The present invention has the following effects due to the above configuration. According to claim 1, when polishing the surface of ceramics,
First, the work piece is polished with a first abrasive having a hardness higher than that of the work, and then a second abrasive having a hardness lower than that of the work is mixed with the abrasive. This is a surface processing method for ceramics, which comprises polishing, then gradually increasing the proportion of the second abrasive grains, and finally polishing the workpiece with the second abrasive grains. Since the work piece is first polished with a higher hardness than the work piece, the processing time is greatly shortened.Finally, the work piece is polished with a lower hardness than the work piece. As a result, a very smooth processed surface can be obtained.

According to a second aspect of the present invention, the ceramic work piece is sandwiched between a pair of plates, the plates are vibrated to rotate the work piece, and a liquid containing abrasive grains around the work piece. In the ceramic surface processing method of polishing the side surface of the work piece with the abrasive grains interposed between the vibrating plate and the side surface of the work piece to rotate, A work piece is polished with a first abrasive grain, and then a second abrasive grain having a hardness lower than that of the work piece is mixed with this abrasive grain, and then a second abrasive is gradually added. The method for surface processing of ceramics is characterized by increasing the ratio of the abrasive grains and finally polishing the work piece with the second abrasive grains.

Since the workpiece is processed while rotating by rotation by vibrating, a headstock and a motor for rotating the workpiece are not required, so that the entire apparatus is simplified.
Further, since the side surface of the work piece is polished by the abrasive grains interposed between the vibrating plate and the side surface of the work piece that rotates, the relative slip amount between the work piece and the tool (vibrating plate) can be minimized. It is possible to obtain a very good surface without worrying about scratching the surface of the work piece.

According to a third aspect of the present invention, the ceramic is silicon nitride, the first abrasive grains are aluminum oxide, and the second abrasive grains are chromium oxide. Hard aluminum oxide can reduce the processing time. In addition, due to the partial solid-state reaction of aluminum oxide and the solid-state reaction of chromium oxide,
A very smooth processed surface can be obtained. Therefore, a very smooth processed surface can be processed in a short time.

According to a fourth aspect of the present invention, there are provided a pair of plates sandwiching a side surface of the ceramic workpiece, a vibrator for vibrating these plates to rotate the workpiece, and a side surface and the plate of the workpiece. Between the first abrasive grain having a hardness higher than that of the workpiece and the second abrasive grain having a hardness lower than that of the workpiece at a predetermined ratio. A ceramic surface processing apparatus is constituted by the processing liquid supply means for supplying the two abrasive grains.

Since the work piece is rotated and processed by the vibrator, the headstock and the motor for rotating the work piece are not required, so that the entire apparatus is simplified. Also,
Mixed abrasive grains formed by mixing a first abrasive grain having a hardness higher than that of the workpiece and a second abrasive grain having a hardness lower than that of the workpiece at a predetermined ratio, or the first abrasive grain or the second abrasive grain. Since the processing liquid supply means for supplying the abrasive grains is provided, the processing efficiency is high and an extremely good surface can be obtained in a short time.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of a ceramic surface processing apparatus of the present invention.

FIG. 2 is a plan sectional view of a ceramic surface processing apparatus of the present invention.

FIG. 3 is a surface processing principle diagram according to the present invention.

FIG. 4 is a diagram showing a ratio of abrasive grains supplied by the ceramic surface processing apparatus according to the present invention.

FIG. 5 is a diagram of another embodiment of the ceramic surface processing apparatus of the present invention.

FIG. 6 is a processing line layout diagram in which the ceramic surface processing apparatus of the present invention shown in FIG. 5 is arranged.

FIG. 7 is a diagram showing a ratio of abrasive grains used in each step of the processing line shown in FIG.

[Explanation of symbols]

1, 20 ... Surface processing device, 5, 8, 27, 32 ... Rubber plate, 7, 24 ... Oscillator, 16 ... Processing liquid supply means, 16
a, 16b ... Machining liquid container, 19a ... 1st abrasive grain (high hardness abrasive grain), 19b ... 2nd abrasive grain (low hardness abrasive grain).

Claims (4)

[Claims] 1. When polishing a surface of ceramics, first, a work piece is polished with a first abrasive grain having a hardness higher than that of the work piece, and then the abrasive grain has a hardness lower than that of the work piece. Polishing with a mixture of the second abrasive grains, then gradually increasing the proportion of the second abrasive grains, and finally polishing the work piece with the second abrasive grains. Characteristic ceramics surface processing method. 2. A ceramic work piece is flanked by a pair of plates, the plates are vibrated to rotate the work piece, and a liquid containing abrasive grains is supplied to the periphery of the work piece. In a surface processing method of a ceramic for polishing a side surface of a workpiece with abrasive grains interposed between a vibrating plate and a side surface of a workpiece to be rotated, firstly, a first surface having a hardness higher than that of the workpiece is used. Abrasive grains are used to polish a workpiece, and then abrasive grains are mixed with a second abrasive grain having a hardness lower than that of the workpiece, and then the second abrasive grains are gradually added. Increase the proportion of
A surface processing method for ceramics, which comprises finally polishing a workpiece with a second abrasive. 3. The ceramic is silicon nitride,
The ceramic surface processing method according to claim 1 or 2, wherein the first abrasive grains are aluminum oxide and the second abrasive grains are chromium oxide. 4. A pair of plates sandwiching a side surface of a ceramic work piece, a vibrator that vibrates these plates to rotate the work piece on its own axis, and a plate between the side surface of the work piece and the plate. Mixed abrasive grains or first abrasive grains or second abrasive grains obtained by mixing a first abrasive grain having a hardness higher than that of the workpiece and a second abrasive grain having a hardness lower than that of the workpiece at a predetermined ratio. A ceramic surface processing apparatus comprising a processing liquid supply means for supplying grains.