JPS62228306A - Tool for machining ceramics - Google Patents

Abstract

PURPOSE:To improve fracture and abrasion resistance and enhance machining efficiency by applying a specific value to the front top rake of a cutting edge, the intersection angle of a rake face and a flank, a side cutting edge angle, the front top rake of a heat-resisting diamond tool and the like. CONSTITUTION:When the front top rake theta1 of a sintered diamond tool is taken at -15 deg.--60 deg., and the intersection angle theta2 of a rake face and a flank at 90 deg. or more, the fracture and abrasion resistance of the tool is improved. Furthermore, in machining ceramics of high hardness and strength, the adoption of a side cutting edge angle theta3 at 60 deg.-89 deg. lessens a stress working on a cutting edge, enlarges a cutting edge length, dissipates heat generated during machining and improves the abrasion resistance of the tool. Also, a heat-resisting diamond tool is less than a normal sintered diamond tool in strength, but the application of the front top rake theta1 of -25 deg.--50 deg. to the heat-resisting diamond tool alleviates a shear force working on the cutting edge thereof and enables high speed machining, thereby improving efficiency.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a tool for cutting ceramics with high efficiency.

Problems with conventional technology Alumina ceramics have traditionally been used for cutting tools and machine parts, but recently fine ceramic materials such as silicon nitride, silicon carbide, and zirconia have improved their heat resistance, wear resistance, and light weight. A new generation of mechanical structural parts that has attracted attention due to its chemical stability.

Development is actively underway to put it into practical use in wear-resistant materials, electronic parts, medical parts, and other applications. Ceramics generally have high hardness and are brittle, making it difficult to process them efficiently, and this is thought to be a major reason for the delay in their practical application.

Although various studies have been conducted on the processing of ceramics, the current processing mainly involves grinding, cutting, or lapping with a diamond grindstone.

If the appropriate diamond grinding wheel and processing conditions are set,
Although it is possible to process these ceramics,
There are problems in processing efficiency, processing cost, processing shape, etc.

In order to make full use of these materials, processing efficiency is high,
It would be good if it were possible to perform cutting processing with excellent processing flexibility.

It is generally said that tool materials need to have a hardness 4 to 5 times that of the workpiece material, but from this point of view, sintered diamond tools are the first tools that can be used to cut ceramics. Considered a candidate.

Therefore, as shown in Fig. 1, the sintered diamond 2 bonded to the cemented carbide was further brazed to the cemented carbide, and the cutting edge radius of the tool was machined to IIIm. was cut. As a result, after cutting for 5 minutes, the sintered diamond was damaged on the rake face and cutting became impossible.

In addition, silicon nitride with a Vickers hardness of 1600 was cut in the same manner as alumina ceramics, but the sintered diamond broke off on the rake face after 1 minute of cutting, making it difficult to cut ceramics practically with current sintered diamond tools. is difficult.

The present inventors investigated why defects occur in sintered diamond. As a result, ceramics have high hardness,
The cutting edge of sintered diamond is difficult to stick to the workpiece, and the thrust force increases (particularly when the cutting edge of the tool wears out, the force increases further). However, since sintered diamond is a brittle material, it has high compressive strength but low tensile force. Since the shear strength is low, it is presumed that the cutting edge cannot withstand this stress and the cutting edge will chip or break.

Therefore, in order to process ceramics practically, this defect must be prevented.

Means for Solving Problems The inventors of the present invention conducted research on preventing cutting edge breakage when cutting ceramics, and as shown in Figure 1, the sintered diamond angle θ + wots° ~ - 60°, and the intersection of the rake face and flank face: angle θ2 is 9
It has been found that by adjusting the angle to 0° or more, not only fracture resistance but also wear resistance is greatly improved.

Furthermore, when cutting ceramics with high hardness and strength, the side edge angle θ should be set between 60' and 89° as shown in Figure 2.
By doing so, the wear resistance will be improved.

In particular, if a sintered diamond having a heat resistance of 1,000 or higher is used, it can be estimated that chipping can be prevented and wear resistance can be improved by using high hardness ceramic as follows.

When cutting ceramics, chips are generated by brittle fracture of the workpiece material, so the principal component force and feed component force are low, but the hardness of the ceramic is high, so as mentioned above, the cutting edge is difficult to stick, and the back force is high. Therefore, a large shear force is applied to the tool cutting edge.

This shearing force decreases as the rake angle becomes smaller.Also, if the rake angle is smaller than 160', the thrust force becomes abnormally high and cutting is impossible (this is why -15° and 60° are set. Regarding the intersection of the flank and the flank surface = angle θ2, if the angle is less than 90°, the strength of the cutting edge will be insufficient and the cutting edge will break.

When cutting ceramics, chips are generated in the workpiece due to brittle fracture as described above, but as shown in Figure 3, when the depth of cut is large, the scale of the fracture increases and the stress applied to the tool edge increases. Wear progress due to chipping is significant. In such a case, in order to reduce the depth of cut, the side edge angle θ may be increased. Particularly when cutting hard ceramics, setting θ3 to 60° to 89° reduces the stress applied to the cutting edge and increases the length of the cutting edge, which is effective in dispersing the heat generated during cutting. be. The effect is small when θ□ is less than 60°, and when θ3 is 89°
If it exceeds , the cutting edge length will increase and the back force will increase. In particular, in sintered diamond, the coarser the particle size of the diamond particles, the higher the wear resistance, but the lower the strength. In addition, when cutting ceramics, many ceramics have low thermal conductivity, and there are few stars from which the heat generated in the chips can be removed, resulting in a high temperature at the cutting edge of the tool. Sintered diamond is 25° stronger than regular sintered diamond.
By setting the angle to ~-50°, the shearing force applied to the cutting edge of the tool is relaxed and used, thereby making it possible to cut ceramics at high speed and further improving machining efficiency.

In the present invention, the round chip rake angle is -15° to -6
If the cutting angle is clamped at 0°, the cross-cutting angle can be adjusted depending on the depth of cut, and the sintered diamond surface is wide, which is advantageous for heat dissipation, and the cutting edge will not wear out. It is very economical because the position of the cutting edge can be easily changed.

Examples will be described in detail below.

The bending strength was 70 kg/m by processing the cylindrical disc into a disc with a diameter of 8.2 mm and fixing it in holders with various rake angles.
m”, silicon nitride with a Vickers hardness of 1500 is cut to a depth of 0.
5mm”, feed 0.05mm/rev, speed 40m/m
It was cut for 3 minutes with an in. Note that the intersection of the rake face and the flank face = angle θ2 is 90°. The results are shown in Figure 3.

When cutting with silicon nitride, in addition to flank wear, the edge of the cutting edge was damaged at the border of side relief, making it impossible to cut.

Example 2 ・) Sintered diamond A containing 97% by volume of diamond particles with a particle size of 100 μm or less and the remainder being CO;
The heat-resistant diamond B, in which CO was eluted from the sintered diamond by acid treatment, was processed to a diameter of 13 mm and fixed in holders with scoop angles of -15°, -25°, and -45°, and had a Vickers hardness of 1600. Bending strength: 80kg/mm.

Cutting silicon nitride at 50 m/min, Loom/min, depth of cut 0.5 mm, feed 0, 05 mm/rev at 10
Cut for a minute.

The results are shown in Table 1. Note that heat-resistant sintered diamond B did not deteriorate even at 1000°C.

Table 1: A piece of cemented carbide sintered diamond with a grain size of 30 was machined as shown in FIG. The intersection angles θ2 between the rake face and the flank face were set to 80', 90°, and 120°. This tip was fixed in a holder so that the rake angle was 130°, and the alumina with a Vickers hardness of 2200 was cut into 0.
．． 5mm, feed rate 0.1mm/rev, speed 50-min,
It was cut for 20 minutes. The results are shown in Table 2.

Table 2: A composite sintered body in which sintered diamond with grain size of 20 mm is bonded to cemented carbide is processed into a rectangle of 3 mm x 5 mm.
Five types were prepared: 50°, 60°, 80°, and 85°.

The rake surface was set to 130°. Using this tool, silicon nitride with a Pinkers hardness of 1400 was cut at a cutting speed of 50 m/min, 1 cutting depth of 0.3 mm+, and a feed rate of 0.08 mm/rev.

The results are shown in Table 3.

As detailed in Table 21 of the invention, the tool of the present invention has excellent chipping resistance and wear resistance when cutting ceramics, so it is particularly suitable for cutting fine ceramics during pouring. If used, it will be possible to process with high efficiency and low cost.

[Brief explanation of drawings]

Fig. 1 is a front sectional view when ceramic is being cut with the cutting tool of the present invention, Fig. 2 is a top view of Fig. 1, and Fig. 3 is the test result of Example 1 (rake angle and Figure 4 is a top view (a, c) and front view (opening, 2) of the sintered diamond tool used in Example 3, and Figure 5 is a diagram showing the wear rate of the tool used in Example 4. They are a plan view (a) and a side view (b). 1.5.9: Ceraminocou work material, 2. 14.17.
22: Rake face, 3, 15.18, 25: Relief face,
4,6,1013.19.21: Sintered diamond,
16, 20, 23: Cemented carbide joined to sintered diamond, 24: Cemented carbide shank, 7, 11: Position of sintered diamond tool after 1 rotation, 8.12: Chip cross-sectional shape, θ, : The angle formed by the rake angle (center line and rake) t, which is negative if it is above the center line. ), θ2: intersection angle of rake face and flank face, θ3 = side edge angle. Figure 1

Claims (4)

[Claims] (1) The front rake angle θ_1 of the cutting edge is -15° to -60°, and the intersection angle θ_2 between the rake face and flank face is 90°
The above provides a ceramic processing tool characterized in that the cutting edge material of the tool is made of sintered diamond. (2) The ceramic processing tool according to claim 1, wherein the side edge angle θ_3 is 60° to 89°. (3) The ceramic processing tool according to claim 1, wherein the sintered diamond has a heat resistance of 1000° C. or higher. (4) The ceramic processing tool according to claim 1, wherein the front rake angle θ_1 is -25° to -50°.