JP2995320B2 - Fine drilling method for ceramics - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for efficiently drilling a small diameter hole in hard materials such as fine ceramics and glass.

[Prior art]

[0002] In the drilling of fine ceramics, which are difficult-to-machine materials, the drilling diameter is becoming finer and the number of drillings per product is increasing with the refinement of processed products. Therefore, conventional machining methods by direct contact of tools cannot be used, and new machining methods such as laser machining, electric discharge machining, and A
A method has been proposed in which a tool does not directly contact a processing material such as JM processing. However, these processing methods still have many problems in processing cost, processing accuracy, and particularly processing efficiency.

On the other hand, among conventional processing methods, ultrasonic grinding is the most reliable processing method at present in terms of perforation shape accuracy. This is a processing method in which, in addition to grinding by rotation of an abrasive drill, an impact force of longitudinal vibration by ultrasonic waves is applied, and a workpiece is gradually crushed and drilled.

[0004] When the drilling diameter is 2 mm or more, a drilling method using a drill can use a cylindrical core drill for the purpose of reducing grinding resistance and jetting cutting water. Therefore, tool cost and machining efficiency are reduced. Both are the most frequently used processing methods at present.

[0005] However, when the diameter of the perforation becomes smaller than 1 mm, a hollow core drill cannot be manufactured, and only a solid drill can be used. Then, as the drill diameter becomes smaller, the buckling rigidity of the drill is significantly reduced. Therefore, in this case, the drilling of the fine pore diameter to the ceramics by ultrasonic grinding is a process of “multi-stage repetition of minute cuts” in order to secure the strength of the drill and discharge the grinding chips, and the processing time is remarkable. It becomes longer and the processing efficiency decreases.

[0006]

SUMMARY OF THE INVENTION Research and development have been made on a method for dramatically improving the efficiency of drilling a fine hole in ceramics while utilizing ultrasonic grinding with good finished dimensional accuracy. The biggest reason for the reduction in the processing efficiency of ultra-fine drilling by ultrasonic grinding is that the rigidity of the drill is reduced due to the reduction in the diameter of the processing drill. Therefore, to increase the rigidity of the drill, we tested changing the material of the drill core from conventional plain steel to heat-treated alloy steel, cemented carbide, or fine ceramics. Obtained.

In order to further improve the processing efficiency, it has been found that it is effective to divide the drilling step into two in accordance with the function of the drilling. That is, the drilling by the ultrasonic grinding is limited to the finishing, and the drilling up to the penetration with a large processing load is performed by a drilling method with low processing accuracy but high processing efficiency. That is, it is to be a two-step process of “primary drilling: coarse drilling by an arbitrary processing method” and “secondary drilling: finished drilling by ultrasonic grinding”. The problem to be solved by the present invention is how to effectively apply ultrasonic grinding with high processing accuracy in a series of drilling steps.

[0008]

The first means is as defined in claim 1. "In the drilling of fine ceramics, the workpiece and tool are directly
After drilling a hole to penetrate using a processing method that does not make contact , a second finishing process is performed using diamond or cBN.
A drilling method using a drill manufactured by electrodeposition of the

The second means is as defined in claim 2.
"In the drilling of fine ceramics,
When a large number of holes with a diameter of 1 mm or less are continuously processed, the workpiece and the tool come into direct contact as primary roughing.
After drilling a hole through utilizing free machining method, the secondary finishing, using actual drilling in a cylindrical produced by electrodepositing diamond or cBN, grinding by applying ultrasonic vibration It is a processing method that specializes in doing. ''

[0010] In the first roughing method of the first and second aspects, a method of “working in which the workpiece and the tool do not directly contact with each other is performed.
The method of “ drilling” or “ultrasonic grinding is less effective” than the “drilling” performed in the second stage,
Processing methods that do not allow a processing tool to come into contact with a work material, which is far superior in processing efficiency, such as laser processing, electric discharge processing, sand blast processing, and water jet processing, are targets.

According to the second aspect of the present invention, the diameter of the fine holes to be drilled is set to 1 mm or less because a core drill can be used for drilling holes having a diameter larger than this, and the present invention is not necessarily applied in terms of processing efficiency. Because there is no.

The drill used for the secondary finishing is a cylindrical solid drill blade manufactured by electrodepositing diamond or CBN, because the diameter of the drill is 1 m.
m or less, the only practical drill is an electrodeposition drill,
At the same time, a core-shaped drill cannot be manufactured, and the shape of the drill becomes a solid solid type.

[0013]

The following describes how the feature of the present invention, "separating the drilling step into roughing and finishing", which is a feature of the present invention, works. As a matter of course, the time required for the rough processing until the penetration can be significantly reduced as compared with the conventional drilling or ultrasonic grinding.

In the secondary drilling, only the finishing process of the hole diameter is performed for the hole penetrated by the roughing, so that the grinding amount is small and the grinding resistance is remarkably small. For this reason, even with an ultrafine drill having a small rigidity, the grinding speed can be made higher than in the past, and the amount of one grinding can be increased, so that the number of repetitions for drilling can be reduced. This also contributes to the fact that the grinding chips can be directly discharged by the flow of the cooling water, since the finishing process is a perforation in the through hole.

[0015]

[Example] Drilling is divided into "primary: roughing" and "secondary: finishing", and AJM with high processing efficiency as roughing
A test was conducted in which the method was adopted and an ultrasonic grinding method was used in combination as a finishing method. The AJM method is a method in which fine abrasive powder is injected into a workpiece by high-pressure gas to perform drilling. Since the processing progresses due to the accumulation of brittle fracture of the workpiece, a large number of holes are formed. It can be performed in a short time and is suitable for processing hard and brittle materials.

The processing conditions for the primary coarse perforation by the AJM method are shown below. "Processing conditions for rough processing by AJM method" Workpiece material: glassy carbon Plate thickness: 4 mm Abrasive particles: SiC Particle size: 58 μ Carrier gas: nitrogen Pressure: 2 MPa Nozzle used: 0.68 mm Target drilling diameter: 1.5 mm

The finishing conditions of the ultrasonic grinding are shown below. "Finishing conditions by ultrasonic grinding" Finishing drill: Electrodeposited diamond drill (solid type) Outer diameter: 1.85mm Finishing drilling mode: G72 (high-speed deep drilling cycle) G82 (deep drilling cycle) FIG. 1 shows the drilling mode tested in the finishing process.

Table 1 shows the measurement results of the drilling time and the grinding resistance during drilling obtained by the test.

[Table 1]

As described above, in comparison with the conventional method using only one step of ultrasonic grinding, the two-step drilling according to the method of the present invention requires a longer drilling time even in the “drilling mode G83” which has been conventionally used. In the case of "perforation mode G73", a remarkable time reduction of 1/5 has been achieved. Then, the grinding resistance is reduced to 40% of that of the conventional method in both the “perforation modes G83 and G73”. As described above, according to the present invention in which the drilling step is performed in two steps of “rough processing and finish processing” from the beginning of the processing, advantages in both reduction of the processing time and extension of the tool life were confirmed.

[0020]

According to the present invention, since the grinding resistance in the finishing process is remarkably reduced, a mode in which the number of repetitive cuttings of the drill is small as shown in FIG. Can be shortened. That is, the effect of the present invention is that, first, the processing efficiency is remarkably improved as compared with the conventional method. For example, in the case of a multi-hole processed product having a hole diameter of 0.8 mm, a depth of 3 mm, and a number of holes of 1733, such as a plasma etcher electrode, the conventional processing time of 90 seconds / piece is obtained by the method of the present invention. If it becomes about 1/5, product 1
The individual machining time can be greatly reduced from the conventional 52 hours to 12 hours. Recently, a large number of fine and perforated products are increasing, and the present invention is effective for improving the processing productivity.

Further, since the grinding resistance is greatly reduced by the method of the present invention, it can be estimated that if the tool life is reduced in proportion to this, it will be about twice or more.

In the case of drilling of 1 mm or less, it is the greatest utility of the present invention that a solid drill having a small diameter can be used without problem in place of a core drill.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a drilling mode used for finishing and a pattern of a vertical cutting movement of a drill.

Claims (2)

(57) [Claims] In the drilling of fine ceramics, a workpiece and a tool are directly contacted as a primary roughing.
A drilling method characterized by drilling a through-hole using a drilling method that does not touch, and then performing secondary finishing using a drill manufactured by electrodepositing diamond or cBN. 2. In the drilling of fine ceramics, when a large number of holes having a fine diameter of 1 mm or less are continuously formed, a workpiece and a tool are directly processed as a primary roughing.
After drilling a hole to penetrate using a processing method that does not make contact , a second finishing process is performed using diamond or cBN.
A grinding method by applying ultrasonic vibration using a cylindrical solid drill manufactured by electrodeposition of a material.