JP2002086263A - Joining method for cemented carbide alloy plate and shank - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a joining method for a cemented carbide alloy plate having a large area and a shank. SOLUTION: After brazing a plurality of metallic small pieces 2 to the cemented carbide alloy plate 1, they are mechanically joined to the shank 6 through an attachment 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a joining method when a cemented carbide sheet is joined to a shank.

[0002]

2. Description of the Related Art Cemented carbides have excellent wear resistance and are widely used for cutting tools and wear-resistant tools. However, the amount of cemented carbide is reduced due to its high cost, high specific gravity and heavy tool weight. For the purpose, it is often used in connection with a shank such as steel. In this case, a joining method using brazing, screwing, or an adhesive is used.

[0003]

However, when the cemented carbide sheet and the shank are joined by brazing, the thermal expansion coefficient of the cemented carbide is about 1/2 of that of steel normally used as a shank material. Therefore, when the brazing area increases, the residual stress generated in the brazed portion due to the difference in thermal expansion coefficient between the cemented carbide and the shank material increases. for that reason,
A tool having a large brazing area has a problem in that the tool life is extended due to breakage during brazing, cracking of the cemented carbide part during use, or peeling of the brazed part. Depending on the shape, it may not be possible to manufacture screws or screw holes on the pressing surface, such as powder molding punches, etc. There was also a problem that there is. Bonding with an adhesive has a problem that the adhesive strength and heat resistance are often insufficient, depending on the application.

[0004]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems.
A joining method characterized by brazing a plurality of small metal pieces to a cemented carbide sheet having a large area equivalent to 00 mm x 100 mm or more, and joining the cemented carbide sheet and the shank through the small pieces. It is. That is, in the joining method according to the present invention, a plurality of small metal pieces are first brazed to a cemented carbide sheet as shown in a plan view of FIG. In this case, each brazing area is small, and the residual stress due to the difference in thermal expansion coefficient from the cemented carbide is balanced at each brazing point, and is not added over the entire area of the brazing portion. The residual stress is significantly reduced as compared with the case where the entire surface is brazed, and the limitation on the manufacturable dimensions due to the brazing method is eliminated.

[0005] The size of the small metal piece is from φ20 mm to φ50 mm or from 20 mm × 20 mm to 50 mm × 5 mm.
It is preferable to set it to about 0 mm. φ20mm or 2
If the size is 0 mm × 20 mm or less, a screw hole described later must be reduced, and the screwing strength is insufficient.
If it is 0 mm or 50 mm × 50 mm or more, the brazing area becomes too large, and the effect of reducing the residual stress based on the difference in thermal expansion coefficient decreases. A screw hole is provided on the back side (opposite to the brazing surface) of each of these small metal pieces, and as shown in the sectional view of the joined state in FIG. An attachment for attachment is arranged between the shank and a blind hole for fitting each of the small metal pieces, a through hole for passing a screw, and a counterbore for burying a screw head. We can join by stopping, and
A screw hole is provided so that the shank can be joined by screwing. By doing so, the tool in which the cemented carbide sheet material and the shank are mechanically joined to each other is less likely to cause cracks in the cemented carbide part during use, or to cause accidents such as peeling of the brazed part. , Long life.

Although a normal steel material may be used for the above-mentioned metal piece, the use of a low thermal expansion coefficient alloy such as a super-invar (Fe—Ni—Co) alloy makes it easier to reduce the residual stress. Is more preferable.

Furthermore, when screwing the small metal piece, the attachment and the shank, an adhesive is injected into the gap between them and the inside of the screw hole to prevent loosening of the screw and rattling when the screw is loosened. It is more preferable to use a metal powder-containing adhesive having a relatively high strength and elastic modulus.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment will be described below using a punch of a powder molding die for brick as an example. As shown in the plan view of FIG.
φ40.0 mm × 17.0 mm obtained by tapping a screw hole 5 ′ on a cemented carbide plate 1 of mx 150 mm × 230 mm
Of the low-thermal-expansion-coefficient alloy small piece 2 was brazed to a predetermined position using a silver solder. Next, as shown in the cross-sectional view of FIG. 2, φ40.3 mm for fitting with the columnar piece 2 was attached to a steel attachment 3 of 31 mm × 150 mm × 230 mm.
A blind hole 4 of 17.3 mm, a through hole for a screw, a counterbored hole for burying a screw head, and a screw hole for joining with a shank 6 are machined, and the cylindrical small piece 2 and the attachment 3 are fitted together to form a screw 5. After that, the attachment 3 and the shank 6 were joined with the screws 7. This was finally finished to predetermined dimensions by grinding and polishing. According to such a method, a punch of a powder molding die for a long-lasting cemented carbide brick, which has conventionally been difficult to produce, can be easily produced.

[0009]

As described above, the cemented carbide tool manufactured by the method of joining a cemented carbide sheet and a shank according to the present invention is inexpensive and lightweight compared to a tool entirely made of cemented carbide. In addition, cracking of the cemented carbide part and peeling of the brazed part as in the case of brazing the entire cemented carbide sheet material to a shank are suppressed, and the original life of cemented carbide tools is exhibited, It is extremely useful.

[Brief description of the drawings]

FIG. 1 is a plan view showing a state in which small metal pieces are brazed to a cemented carbide sheet material.

FIG. 2 is a cross-sectional view showing a bonded state of a cemented carbide sheet material to which a small metal piece is brazed, an attachment, and a shank.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cemented carbide plate material 2 Low thermal expansion coefficient alloy small piece 3 Attachment 4 Fitting hole for 2 and 3 5, Screw for screwing 5 '2 and 3 and screw hole 6 Shank 7 Screw for connecting 3 and 6

Claims (2)

[Claims] 1. A method for joining a cemented carbide plate and a shank, comprising brazing a plurality of small metal pieces to a cemented carbide plate and mechanically joining the small piece to the shank via the brazing. 2. The method of joining a cemented carbide sheet material and a shank according to claim 1, wherein a low thermal expansion coefficient alloy is used for the small metal pieces.