JPH03170206A - Cutting tools - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a cutting tool whose cutting edge is made of a hard sintered body.

[Conventional technology]

A typical cutting tool with a hard sintered body made of diamond or high-pressure phase boron nitride attached to the corner of the main body and a cutting edge formed on the sintered body has a shape as shown in Figure 4. It is. The figure shows an example of a throw-away tip, in which a recess 6 is provided at the corner of the main body 5 to serve as a seating surface, and a small piece of the hard sintered body 1 is brazed into the recess. The necessary cutting process is being carried out.

The small piece in the figure is a composite hard sintered body in which a base metal 2 is integrated with the lower part of a hard sintered body 1, but the base metal 2 may be omitted.

[Problem to be solved by the invention]

Since hard sintered bodies are expensive, cutting tools using them, such as indexable chinops, are generally re-ground while being used repeatedly, but this method has the disadvantage that the position of the cutting edge changes. The problem is that, in the case of indexable tips, a holder dedicated to the regrinding chimp is required.

Therefore, there is a need for a cutting tool that has a hard sintered body with a minimum size and can be used without increasing the economic burden even if it is disposable.

However, this type of tool brazes only two surfaces, the bottom surface 3 and the back surface 4, of the hard sintered body or composite hard sintered body with a base metal, so the hard sintered body is made too small in size. In this case, the brazed portion cannot withstand the cutting force and tends to peel off during use. In particular, in the case shown in FIG. 4, the back surface 4 is
Since it is parallel to t, the hard sintered body is likely to peel off due to cutting force, making it impossible to obtain a practical product.

The present invention aims to solve this problem from the viewpoint of the joint structure, make it possible to reduce the size of the hard sintered body, and provide an inexpensive and economical cutting tool for the hard sintered body.

[Means to solve the problem]

In order to solve the above problems, in the present invention, the back shape of the sintered body is formed into a convex shape in the direction of the nose R when viewed from the rake face of the tool.

[Effect]

If the back surface of the hard sintered body is made convex, it will catch on the tool body and produce a mechanical fixing force against the feeding force.

Furthermore, the fixing force is further strengthened due to the pressing force generated by the cutting back force on the joint surface between the convex back surface and the tool body, and as a result, the force that tends to destroy the brazed part is alleviated. Ru.

Furthermore, since the back surface is convex toward the nose R, there is no needless increase in area of the hard sintered body, unlike the case where the rear surface is convex in the opposite direction.

〔Example〕

Embodiments of this invention are shown in FIGS. 1 to 3.

The cutting tool shown in Fig. 1 is made by fixing a base metal 2 to the lower surface of a hard sintered body 1 mainly containing diamond, high-pressure phase boron nitride, or a mixture thereof. 4 is recessed into an arc shape, and this small piece is inserted into the recess 6 provided to fit the corner part of the tool body 5.
and the back 4 are brazed and installed.

On the other hand, in the cutting tool shown in Fig. 2, when the back surface 4 of the composite sintered body is viewed from the rake face, two straight lines intersect at the center at an angle of θ.
It is shaped like a letter and is brazed to the tool body 5.

In addition, the cutting tool in Fig. 3 has a rear surface 4 when viewed from the rake face side.
The shape of is a waveform in which peaks and troughs of angle θ are arranged alternately.

The effects of the present invention will be explained below by taking as an example the cutting of hardened steel, which is a typical example of the use of a cubic boron nitride sintered tool (hereinafter referred to as a PCBN tool).

In the case of hardened blade cutting, among the three cutting forces shown in Fig. 1, namely the principal force Fc, the feed force pt, and the back force Fo, Fo increases with tool wear and is the largest. It is a characteristic.

However, in conventional hard sintered cutting tools as shown in Fig. 4, Fo does not work effectively as a force for absorbing the feeding force Ft, and almost no mechanical fixing force can be obtained with respect to Ft. , the bonding force of the brazed portion alone attempts to withstand the force of PL, and therefore, when the hard sintered body becomes less than a certain size, the force of Ft overcomes the bonding force and the sintered body comes off.

In contrast, in the structure of the present invention, the back surface 4 of the sintered body faces the feeding force direction at an angle, and the sintered body tends to come off mechanically by this angle. Prevent movement.

Furthermore, as explained earlier, the back force Fo, which is the largest in the width of the 3-component cutting force, presses the back surface 4 of the sintered compact against the tool body. It is necessary for the force (Ft) acting on the surface 4 to overcome the force Fo, and these factors together make the resistance to the feed force extremely strong.

Therefore, according to the present invention, even if the sintered body is made small, it is possible to maintain a practical adhesion force.

Note that the object of the invention can be achieved if the shape of the back surface 4 is convex in the direction of the nose R, but in consideration of ease of manufacture, the shape shown in the example is preferable.

Further, in the shape shown in FIG. 2 or 3, the value of θ is preferably in the range of 90 to 170°. If the angle is more than 170°, the mechanical fixing force is likely to be insufficient because it becomes close to a straight line, while if it is less than 90°, the apex portion of 4 becomes weak and may break.

In addition, the shape of the tool body is preferably a chip shape, which uses less material, considering the economic efficiency in the case of disposable use.

Next, the results of the effectiveness confirmation test are described.

In this test, samples ① to ② below were used. The thimbles are all TNMA332 type dip shapes.

・Conventional product with the shape shown in sample Figure 4. Rake surface area of sintered compact 1 - 3mm'' ・Sample ■ Conventional product with the same shape as the sample. Rake surface area of sintered compact 1 - 51I11l2 ・Sample ■ Wooden invention product shown in Figure 2. Sintered compact Rake surface area of 1 - 2
．． 5 torso 2. A cutting test 71 was conducted under the following conditions using the samples described in θ1 and 2.

Work material: SKD11, l{RC62 Cutting speed: 100 ffi/min depth of cut 20.
Pentavalent feed: 0.1 mm/rev dry type As a result, the sintered body of the sample came off from the brazed part after 5 minutes of cutting time, but the sintered body of sample ■ and ■ did not come off even after 20 minutes of cutting time. .

As can be seen from this, according to the present invention, it is possible to realize a tool with no practical problems even if the size of the sintered body is reduced to 1/2 of the conventional size.

〔effect〕

As explained above, according to the present invention, it is possible to reduce the size of the hard sintered body and obtain a fixing force that can withstand cutting force.
It becomes possible to provide a hard sintered compact tool that is more advantageous and inexpensive if it is disposable.

[Brief explanation of the drawing]

1 to 3 are perspective views showing embodiments of the present invention, and FIG. 4 is a perspective view of a conventional example. 1... Hard sintered body, 2... Base metal, 3
...Bottom, 4...Back, 5.
...Tool body, 6...Recess.

Claims (5)

[Claims] (1) A hard sintered body mainly composed of diamond and/or high-pressure phase type boron nitride, or a composite hard sintered body with a base metal fixed to the bottom thereof, is placed in a recess provided at the corner of the main body. In a cutting tool whose back surface is joined and attached and a cutting edge is formed on the hard sintered body, the shape of the back surface of the hard sintered body when viewed from the rake face of the tool is made convex toward the nose R direction. A cutting tool featuring: (2) The cutting tool according to claim (1), wherein the convex shape on the back surface is a circular arc. (3) The cutting tool according to claim 1, wherein the convex shape on the back surface is a V-shape in which two straight sides intersect at an angle of θ at the center. (4) The cutting tool according to claim 1, wherein the convex shape on the back surface is a wave-like shape in which peaks and valleys having an angle of θ are arranged alternately. (5) The cutting tool according to (3) or (4), wherein the θ is 90 to 170 degrees.