JPH01241376A - Manufacture of wear resistant and impact resistant bit - Google Patents

Abstract

PURPOSE:To improve wear resistance and impact resistance of a bit by inserting foil of Ni, Co, Cr, etc., with specific thickness into the joining surfaces between an iron material and a super alloy to join these. CONSTITUTION:The foil of Ni, Co, Cr, etc., with 50-1000mum thickness is inserted into the joining surfaces 2 between the iron material 1a and the super alloy 1b and resistance welding is performed thereon at a current with 20-40A/mm<2>, welding force with 120-400g/mm<2> and welding time of 3-10sec. By this method, the wear resistance and impact resistance of the bit having chips with plate and irregular shapes can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a method of manufacturing a wear-resistant and impact-resistant bit.

[Background of the invention]

A piston is instantaneously operated using electricity, gas, compressed air, etc., and nails are made using a bit fixed to the piston:
In nailing machines that apply impact force to drive nails into wood, etc., wear of the bit is unavoidable due to impact contact between the bit and the nail. As a result, the quality of implantation deteriorates over time.

Therefore, it is known that a cemented carbide is bonded to the tip of a ferrous material bit using brazeability to improve wear resistance. There was a problem in that the bonding strength between the hard metals was low, and the entire cemented carbide part could peel off during nailing operations, making it unusable. For this reason, there has been a strong demand for the development of a method that has excellent bondability with iron-based materials and cemented carbide.

[Purpose of the invention]

An object of the present invention is to eliminate the above-mentioned drawbacks and to provide a manufacturing method for this type of bit that has excellent bondability with ferrous materials and cemented carbide.

[Summary of the invention]

The present invention deals with metals such as Ni, Co, and Cr contained in cemented carbide that have metallurgical solid solubility in Co or Ni, and also have solid solubility in iron-based materials. A strong joint is obtained by interposing a foil between the joining surfaces of cemented carbide and iron-based materials and performing resistance welding. This will be explained using Figure 4.

The bit shown in FIG. 1 is a bit manufactured by the manufacturing method of the present invention, and the bit 1 is made by joining a cemented carbide 16 to the tip of an iron-based material 1a.

Next, to explain the manufacturing method, a foil of Ni, Co, Cr, etc. with a thickness of 50 to 1000 μm is inserted into the joint surface of iron-based material and cemented carbide, and a current of 20 to 40 A/rrn2 and a pressing force of 12
0 to 400 g/m", welding time is 3 to 10 seconds.The current was set to 20 to 40A10n" because
If it is less than 20A/mn2, heat generation is not sufficient, and Ni, Co
This is because foils such as Cr do not diffuse and do not provide sufficient strength at the bonding surface. At 4OA/mm2 or higher, iron-based materials become extremely brittle or melt due to the thermal effects of heat generation, and the characteristics of the material deteriorate. This is because you will lose the. Next, the pressure was set to 120 to 400 g/+um2, which was 120 g/+um2.
This is because if the wI is less than 2, Ni, Co, Cr, etc. foils will form a layer at the joint after welding, causing a decrease in the strength of the bit, and if it is more than 400 g/mm2, deformation will occur in the softened part of the iron-based material. It's for a reason. Also, the welding time is 3 to 1
The reason for setting it to 0 seconds depends on the relationship with the current, but for example, 2 seconds.
This is because when the heating time is set to 0 to 40 A/+a2, Ni, Co, Cr, etc., do not dissolve and diffuse if the heating time is 3 seconds or less, and if it is 10 seconds or more, the iron-based material becomes embrittled due to overheating.

The thickness of Ni, Go, Cr, etc. foil is 50 to 1000 μm.
This is because if the thickness is less than 50 μm, the diffusion layer necessary for bonding cannot be obtained, and if it is greater than 1000 μm, no increase in bonding strength is observed, and workability becomes unstable, which tends to cause variations in quality.

Here, the range in which the strongest bonding strength can be obtained by main bonding is a current of 30 to 35 A/mm" and a pressing force of 250 to 300
g/urn”, welding time 6-8 seconds, Ni foil thickness 200
~400 μm.

〔Effect of the invention〕

According to the present invention, by joining a ferrous material and a cemented carbide by a resistance welding method using a foil such as Ni, Co, or Cr as a binder, the wear resistance of a bit having a plate and an irregularly shaped tip can be improved. Impact resistance can be improved.

[Brief explanation of the drawing]

FIG. 3 is a diagram showing changes in shear strength of a welded portion when the thickness of the welded portion is changed. In the figure, 1 is a bit, 1a is an iron-based material, 1b is a cemented carbide, 2 is a joint, and 3 is a diffusion layer. Name of patent applicant Hitachi Koki Co., Ltd. Kaya 1 (21 $2 [21 No. 30

Claims (2)

[Claims] (1) In a bit formed by bonding a cemented carbide to the tip of a ferrous material, the bonding surface between the ferrous material and the cemented carbide has a
A method for manufacturing a wear-resistant and impact-resistant bit characterized by inserting and bonding a foil of Ni, Co, Cr, etc. with a thickness of ~1000 μm. (2) The joining means has a current of 20 to 40 A/mm^2,
Bonding time 3-10 seconds, pressure 120-400g/mm^
2. The method for manufacturing a wear-resistant and impact-resistant bit according to claim 1, wherein the method is resistance welding.