JP2558771B2 - Cutting tools - Google Patents

Description

TECHNICAL FIELD The present invention relates to a cutting tool having a hard sintered body such as a high-pressure phase boron nitride sintered body or a diamond sintered body as a cutting edge.

[Conventional technology]

Conventionally, as a tool for machining a high hardness material or a difficult-to-cut material, a hard sintered body such as a high-pressure phase boron nitride sintered body or a diamond sintered body is joined as shown in FIGS. 4 to 6. Cutting tools such as indexable inserts and grooving tools that are used as cutting edges are known.

As shown in the figure, this tool joins a cutting blade piece 11 made of a hard sintered body to the upper surface of the shank 10 formed in accordance with the processing form by brazing or the like, and the upper surface of the cutting blade piece 11 A cutting edge is formed at a ridge intersecting with the side surface, and the cutting edge piece 11 is usually joined to the corner portion of the shank 10 through the cemented carbide 12. The shank 10 is made of a material that is softer and has a higher toughness than the cutting blade piece 11. In the case of a throw-away tip or a grooving tool, a cemented carbide is generally used.

[Problems to be Solved by the Invention] However, in the above cutting tool, the cutting blade piece 11 is generally formed by cutting a disk-shaped blank of a relatively large hard sintered body into a predetermined shape. Because of this, the cutting edge
The upper surface of 11 is a flat surface with no unevenness, and when cutting is actually performed, the chips will grow long and become entangled with the tool cutting edge and the workpiece, damaging the cutting edge and scratching the workpiece surface. There is a problem called.

On the other hand, in order to deal with such a problem, a tool in which a breaker groove 13 is provided on the upper surface of the cutting blade piece 11 as shown in FIGS.

However, hard sintered bodies have high hardness and poor machining characteristics, so it takes time to form breaker grooves by grinding, and in reality, groove formation by grinding or electrical discharge machining is expensive. Is being carried out. However, the hard sinter itself is very expensive, and when this kind of tool is further subjected to grinding or electric discharge machining, there is a problem that the manufacturing cost increases and the tool price increases.

Furthermore, due to poor processing characteristics, the breaker shape must be a simple shape such as a groove or step, and there is a problem that an optimum breaker shape cannot be formed.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a cutting tool that can be equipped with an optimum breaker without increasing the cost of the tool.

[Means for solving problems]

In order to solve the above problems, the present invention, the cutting blade piece of the hard sintered body, and the shape along only the vicinity of the cutting blade, the top surface of the shank continuous with the upper surface of the cutting blade piece, provided with a chip breaker, Further, the shank is divided into a breaker member to which a chip breaker is attached and a support member to which the breaker member and the cutting edge piece are attached.

Examples of the hard sintered body in the present invention include a diamond sintered body, a hard sintered body obtained by sintering high-pressure phase type boron nitride such as cubic boron nitride, and wurtzite type boron nitride. Usually, these sintered bodies have a poor brazing property, so that the hard sintered bodies are bonded onto a cemented carbide. That is, brazing on the cemented carbide surface compensates for the poor brazing property of the hard sintered body itself.
As the shank used in the present invention, it is desirable to use a cemented carbide which is far superior in workability to a hard sintered body.

The feature of the present invention is that it does not have the shape shown in FIG.
By intentionally applying a complicated process to the shank part and making the hard sintered body itself uneven,
The cost of forming the breaker itself is significantly reduced.
Conventionally, since there are structures shown in FIGS. 4, 5, and 6, there is shown in FIG. 7 in order to consider providing a breaker at a portion integrated with a cutting blade, starting from this structure. Such breakers were first invented. The inventors have made it possible to install a breaker at a cost of 1/5 that of the conventional art by overcoming such an existing concept and reconsidering the configuration of the hard sintered body tool.

In the present invention, in order to reduce the installation cost of the chip breaker, the shank is divided into a breaker member and a supporting member, a chip breaker is formed on the breaker member, and the cutting blade piece of the breaker member and the hard sintered body is used as the supporting member. Brazing to the formed mounting recess. In this way, the chip breaker can be formed on the breaker member made of cemented carbide at a low cost by a method with good workability. In addition, since the breaker member is independent of the shank support member and can be replaced only, it is possible to install the chip breaker of the optimum shape by replacing only the breaker member, which is also economical. Be advantageous to.

The present invention is particularly effective for the grooving tool shown in FIG. That is, in the case of a grooving tool, if there is no breaker, there is a problem that continuous chips are discharged toward the front and wrapped around the work, etc. However, by adopting the structure shown in FIG. Can be divided into

〔Example〕

Embodiments of the present invention will be described below with reference to the accompanying drawings.

1 (a), (b) and (c) show an embodiment in which the present invention is applied to a triangular throw-away tip, and a shank 1 is composed of a breaker member 1a and a support member 1b. The breaker member 1a is brazed to the mounting recess 3 provided at the corner of the support member 1b, and a chip breaker including a plurality of protrusions 4 and 5 is formed on the upper surface of the breaker member 1a.

The cutting blade piece 2 is formed in a substantially V-shaped narrow frame shape corresponding to the shape of the corner portion of the shank 1, and is provided with a breaker member.
It is attached to the recess 3 so as to surround 1a and integrally joined to the support member 1b by brazing.

The cutting blade piece 2 is formed so that the upper surface 2a thereof is substantially aligned with the upper surface of the shank 1 when attached to the shank 1, and the side surface 2b is ground in a state of being joined to the shank 1, A cutting edge is formed at the intersection edge of the surfaces 2a and 2b.

In the cutting tool configured as described above, the chips generated by the cutting edge contact the protrusions 4 and 5 on the upper surface of the breaker member when flowing out on the rake surface of the upper surface of the cutting blade piece 2 and the upper surface of the shank 1. As a result, a braking force is applied, which causes deformation or breakage. In this case, since all the cutting blades used are surrounded by the cutting blade pieces 2 made of a hard sintered body, there is no deterioration in wear resistance, and there is a structure in which the entire corner portion is covered with the cutting blade pieces as in the conventional case. It is possible to obtain a tool life almost equal to that.

In order to form the protrusions 4 and 5 on the breaker member 1a made of cemented carbide, it suffices to provide protrusions corresponding to the above-mentioned protrusion shape on the die for sintering, and the protrusions are not provided in terms of manufacturing cost. It can be formed at about the same cost as a shank.

FIGS. 2 (a), (b) and (c) show another embodiment applied to a throw-away tip, in which a strip-shaped cutting blade piece 2'is attached to a corner portion of a shank 1 '. A recess 3'is formed, and a breaker member 1a having a breaker groove 7 is brazed to the recess 3 '. The breaker groove 7 is preferably formed before the cutting blade piece 2'is joined to the recess 3 '. If the breaker shape is a simple groove as shown in the figure, inexpensive machining can be performed by machining or electric discharge machining. Cemented carbide (compacted powder) before sintering can be easily cut, so if a breaker is attached at this stage, even if a slightly complicated breaker is machined, the labor and cost of processing become a hard sintered body. Compared with the case with a breaker, it is greatly reduced.

FIGS. 3 (a), (b) and (c) show an embodiment applied to a grooving tool, and a shank 1 ″ is a breaker member 1a having a chip breaker shape formed in advance on its upper surface, and its breaker. It consists of a member 1a and a supporting member 1b that supports the cutting blade piece 2 ", and the cutting blade piece 2" that is formed in a U shape in accordance with the groove shape is provided in the recess 3 "provided in the supporting member 1b. Join by brazing. The breaker member 1a is fitted between the cutting blade piece 2 ″ mounted as described above and the rear surface of the recess 3 ″, and brazed to the support member 1b.

By using the breaker member 1a in this manner, it is possible to arrange the chip breaker having the optimum shape along the cutting edge even at the position surrounded by the cutting edge piece of the hard sintered body.

Incidentally, in order to see the performance of the cutting tool according to the present invention, a comparative test with a conventional example was conducted. The target tool is the grooving tool shown in Fig. 3 and the conventional grooving tool shown in Fig. 5, and the shank and breaker members are made of cemented carbide and the cutting blades are made of cubic boron nitride. It was formed of a high-pressure phase type boron nitride sintered body containing 60% by volume.

The test was carried out by grooving the outer circumference of a steel round bar quenched in HRC60 at a cutting speed of 100 m / min and a feed rate of 0.1 mm / rev. As a result, in both the cutting tools of the present invention and the conventional example, no damage to the cutting edge was observed, the same amount of flank wear was observed, and a similar tool life was confirmed. Further, in the conventional cutting tool shown in FIG. 5, a phenomenon in which chips are elongated and wrapped around the work piece during cutting was observed, but in the cutting tool of the present invention shown in FIG. 3, the chips are spirally wound by the breaker member 1a. Curled into pieces and divided.

〔The invention's effect〕

As described above, in the present invention, since the chip breaker is not provided on the cutting blade piece but is provided on the shank formed of cemented carbide or the like, molding of the breaker is facilitated and the manufacturing cost is reduced. Therefore, it can be formed at a tool price almost the same as that of a tool without a breaker. Also,
Since the chip breaker forming part of the shank is independent as a breaker member and the chip breaker of the optimum shape can be selected by exchanging only the breaker member, it is more economical than the one with a chip breaker directly attached to the shank.

In addition, since the cutting edge piece is formed along the cutting edge, a tool life equivalent to that of conventional tools can be obtained, and the breaker shape can be formed into any shape such as grooves or protrusions, which provides the best chip disposability. There is an advantage that the breaker can be formed.

[Brief description of drawings]

1 (a), 2 (b) and 3 (a) are perspective views showing an embodiment of the present invention in an exploded state, respectively (b).
Is a perspective view of an assembled state of the same as above, (c) is a side sectional view of an essential part of the same, (a) of FIGS. 4, 5, and 6 is a perspective view of a conventional tool, respectively. FIG. 7B is a partially longitudinal side view of the same as above, FIG. 7A is a perspective view of another conventional example, and FIG. 1, 1 ', 1 "... Shank, 2, 2', 2" ... Cutting edge piece, 3, 3 ', 3 "... Recess, 4, 5 ... Protrusion, 7 ... Breaker groove, 1a …… Breaker member, 1b …… Support member.

Claims (1)

(57) [Claims] 1. A cutting tool in which a cutting edge piece of a hard sintered body is joined to an upper surface of a shank of a cutting tool attached to a bite holder, and a cutting edge is formed at a cross edge between an upper surface and a side portion of the cutting edge piece. In the above, the cutting blade is formed into a shape only along the vicinity of the cutting blade, and further, the shank is made of a cemented carbide breaker member provided with a chip breaker on the upper surface, and the breaker member and the supporting member for the cutting blade piece. The cutting tool is characterized in that the cutting blade piece and the breaker member are arranged adjacent to each other and joined to a mounting recess provided in the support member.