JPS6320482Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a throw-away tip for a cutting tool, and more specifically, it has a coating layer with high hardness and excellent wear resistance on both main surfaces, and has a through-hole tightening fixing hole in the center. This invention relates to a structural improvement that improves the tightening strength of a throw-away tip.

Conventionally, as shown in FIG.
Throw-away type chips, which are tightened and fixed to the holder 22 by means of an eccentric shaft 23 inserted through a, are widely used for the reason of miniaturizing the device. Since the side wall of the through-hole is partially pressure-welded, it is easily damaged, and this tendency is particularly strong when the material is made of cemented carbide or ceramics, which do not contain enough bonding metal and have poor toughness, and improvements have been requested. .

The present invention was developed in response to the above-mentioned demands, and includes at least 5 vol% of bonding metal on both main surfaces of the main body b, which is made of a sintered hard alloy with high toughness.
a coating layer a made of a sintered alloy or ceramic that does not contain a bonding metal or contains a smaller amount than the main body, exhibits high hardness and wear resistance, and forms the cutting edge;
a, and the through hole 2 provided in the center is located in the covering layer parts 1a, 1, rather than the part 2b of the main body b.
This was achieved by increasing the diameter of a.

As this kind of throw-away tip
As disclosed in Publication No. 36789, a portion B that does not form a cutting edge and an outer portion A that becomes a cutting edge.
By making the above-mentioned part B contain a larger amount of bonding metal than part A, the part that does not form the cutting edge is made of a high-toughness material, and the part that forms the cutting edge is made of a material with excellent wear resistance. Composite chips are known. In this case, the part that does not form the cutting edge has high toughness, and the outer cutting edge part that takes charge of cutting is made of a wear-resistant material.The volume ratio of part B to the whole, and the materials of parts B and A are The effect can be achieved by specifying the combination of , but this is a general relationship between toughness and wear resistance. In this case, the part A of the wear-resistant material that becomes the cutting edge is also partially pressed against the inner wall of the through hole by the eccentric shaft, together with the internal tough part, so while it has high wear resistance, the part A is brittle. There was an unavoidable risk that the device would be damaged, and this could not be an essential solution.

On the other hand, as mentioned above, the throw-away chip of the present invention has high hardness and excellent wear resistance in the center through-hole, but the coating layer on both main surfaces of the main body, which is unavoidably brittle, has a high hardness. Since the diameter is larger than that of the tough main body part, a gap is formed between the tip and the eccentric shaft, and the eccentric shaft presses only the through hole of the high tough main body, which eliminates the risk of chip damage. It has a positive effect.

[Brief explanation of the drawing]

Fig. 1 is an isolated perspective view of the throw-away tip fastened to a holder using an eccentric shaft, Fig. 2A is a perspective view of the throwaway tip of the present invention, and Fig. 2B is a It is a sectional view taken along the K' line. a, a...Coating layer that becomes the cutting edge, b... Main body, 1
a, 1a...Through hole in the coating layer portion, 2...Through hole, 2b...Through hole in the main body portion.

Claims (1)

[Scope of utility model registration request] Both main surfaces of the main body made of a high-toughness sintered hard alloy containing bonding metal at a ratio of 5vo1% or more are coated with a sintered alloy or ceramic that is harder than the main body and has excellent wear resistance and forms the cutting edge. In a device that forms a layer and is tightened and fixed to the holder by an eccentric shaft inserted through a through hole provided in the center, the portion of the coating layer on both main surfaces of the through hole has a diameter larger than that of the main body between the coating layers. Throwaway tip characterized by its large size.