JPS62213920A - Tap treated with ion implantation - Google Patents

Abstract

PURPOSE:To get rid of a tap breakage, by forming a hardened film on both surfaces of a cutting edge part of a taps body holding tenacity or ductility and a groove part by means of ion implantation treatment. CONSTITUTION:Ion implantation treatment is applied to the surface of a tap in a high-speed steel system whereby hardness in the outer layer part is raised up. And, when an N<+> ion is implanted, a friction factor is reduced. With these two actions, abrasion resistance is improved and wearing speed in a cutting edge part becomes lessened, thus the lowering of sharpness is prevented from occurring. On the other hand, since a friction factor in a groove part discharging chips is reduced, discharge of these chips comes so easily, the torque required for thread cutting is reduced so that a breaking accident is preventable.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a tap used for machining screw holes.

[Conventional technology]

Taps made of high-speed steel (hereinafter referred to as high-speed steel) materials are relatively inexpensive and are widely used as thread cutting tools for screw holes. This tap has a one-piece structure, and the entire tap is heat-treated to the hardness required for thread cutting tools, and great care has been taken to make it as tough as possible without sacrificing hardness. For information related to heat treatment of high speed steel, for example, "Tool steel, types and heat treatment methods" Chapter 4 High speed steel and hot working tools, 4.1 General heat treatment of high speed steel, December 1952 Published by Kyoritsu Shuppan Co., Ltd. on May 5th, written by Hisashio Yamato, pages 78 to 91.

[Problem that the invention seeks to solve]

However, when taps made of high-speed steel materials are heat-treated to increase their hardness, it is impossible to simultaneously impart sufficient toughness or ductility due to the characteristics of the material; if heat-treated to lower the hardness, toughness or ductility will increase. However, the cutting edge, which is the most important part of a tap, lacks hardness, sharpness and wear resistance, making it unsuitable for practical use. Additionally, if the hardness is increased to the required level, the toughness or ductility will be insufficient, and when working with small-diameter taps, the tap may break during thread cutting, causing damage to the hole and screw being processed in the broken part. It is very difficult to take it out without removing it, especially if it is of small diameter.

An object of the present invention is to provide a tap that is sharp and hard to break.

[Means for solving problems]

The above object is achieved by forming a hardened film by ion implantation treatment on the surface of the cutting edge and groove of the tap body that maintains toughness or ductility after heat treatment.

[For production]

By applying ion implantation to the surface of a high-speed steel tap, the hardness of the surface layer increases.

Furthermore, it is known that the coefficient of friction decreases when N+ ions are implanted. These two effects improve wear resistance, reduce the rate of wear of the cutting edge, and prevent deterioration in sharpness. On the other hand, since the coefficient of friction of the groove for discharging chips is reduced, chips can be easily discharged, the torque required for thread cutting is reduced, and tap breakage accidents are prevented.

[Example] Hereinafter, an example of the present invention will be explained. Table 1 and Table 2
This figure shows the conditions and effects of ion implantation when ion implantation is performed on the surface of the cutting edge and the groove for discharging chips of a high-speed steel tap.

Table 2 As can be seen from Table 2, in conventional taps, the hardness of both the cutting edge and the tap body is approximately Hv = 800, so
If excessive torque is applied during thread cutting, it may break, and the test results showed that the percentage of breakage was 3. On the other hand, in the tap of the present invention, the surfaces of the cutting edge and the groove have sufficient hardness at Hv=1050, while the center of the tap body has sufficient toughness or ductility at Hv=35Q. The results showed that there was no breakage.

〔Effect of the invention〕

According to the present invention, a cured film can be formed on the surfaces of the cutting edge portion and the groove portion of a high-speed steel tap, and a tap that is sharp and difficult to break can be obtained.

Claims (1)

[Claims] 1. An ion-implanted tap made of high-speed steel, characterized in that a hardened film is formed by ion implantation on the surfaces of the cutting edge and groove of the tap body that maintains toughness or ductility.