JPS63134128A - Method for extending service life of composite cutting tool - Google Patents

Abstract

PURPOSE:To extend the service life of a tool relatively through the improvement of abrasion resistance, the reduction of surface frictional resistance and the improvement of the durability of a large bore part by forming a hardened surface layer via the implantation of ion into the large bore part. CONSTITUTION:Ion 4 such as nitrogen ion is implanted in the large bore machining part 2 of a step drill 1 having both large and small machining parts 2 and 3. As a result, a hardened surface layer is formed on the surface of the large bore machining part 2. And abrasion resistance is remarkably improved due to the hardened layer, a surface abrasion resistance value gives a drop and chips can be smoothly discharged, thereby reducing heat generation due to chip discharge and improving deposit resistance against chips. According to the aforesaid constitution, the formation of constituent cutting edges is substantially simplified, a drop in drill sharpness is lessened and the service life of the drill is substantially extended.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a sub-land drill, a step drill, and a center drill that perform counter-sinking and drilling, chamfering and drilling, double-drilling, etc. with a single cutting tool. This invention relates to complex cutting tools such as drills that have complex machining functions.

[Conventional technology]

Traditionally, in metal drilling, drilling is performed by
In order to perform chamfering, drilling, double hole drilling, etc. in one process, a compound cutting tool such as a subland drill, step drill, or center drill is used. Incidentally, related cutting tools of this type include, for example, Utility Model Publication No. 46-21180.

[Problem that the invention seeks to solve]

Drilling holes such as single countersunk machine screws for hexagonal socket ports can be done in one process such as machining or center hole machining, so it can be used for counterboring and drilling, chamfering and drilling, and double-drilling.
A subland drill, step drill, or pudrill is used. Furthermore, a center drill is used to process the center hole.

Here, in this hole machining, in order to provide one drill with two types of cutting functions, there are a plurality of cutting parts, and the outer diameters thereof generally differ significantly.

For example, in order to drill a hole with a drilling machine, etc., the most appropriate cutting specifications are selected based on the cutting efficiency and tool life, depending on the material of the workpiece, tool material, tool diameter, etc. Therefore, if the rotational speed of the drill is adjusted to the cutting speed of the portion with a small outer diameter, the cutting speed will be too high because the rotational speed will be the same for the portion with a large outer diameter, resulting in significant tool wear and a very short life.

An object of the present invention is to improve the wear resistance of the large diameter portion of the tool, thereby extending the life of the tool as a whole.

[Means for solving problems]

The above problem can be solved by forming a hard coating on the large outer diameter portion of the tool by ion implantation to reduce the amount of wear.

[For production]

By forming a hardened surface layer by ion implantation on the part with a large outside diameter of the tool, it not only improves wear resistance, but also reduces the frictional resistance value of the surface by implanting ions, making it easier to eject chips. In addition, the amount of heat generated due to friction accompanying the discharge of chips is reduced, and the welding resistance with chips can be improved. From the above, due to the reduction in the formation of built-up edges,
There is little deterioration in sharpness and the life of the cutting tool is significantly increased.

From the above, the tool life is relatively increased because the life of the part with a large outside diameter of the tool increases as well as the part of the tool with a small outside diameter where the cutting speed is low.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 3. In this embodiment, a case will be described in which a single drill is used to perform counterboring and drilling in one process as a composite cutting tool.

As shown in FIG. 1, ions 4 such as nitrogen ions are injected into a large diameter machining section 2 of a step drill 1 having a large diameter machining section 2 and a small diameter machining section 3. As shown in FIG. By this ion implantation, a hardened surface layer is formed on the surface of the large-diameter machined portion 2 of the step drill l.

This surface hardening layer significantly improves wear resistance. Furthermore, the surface drop and abrasion resistance values are reduced, and chips can be smoothly discharged, so that the amount of heat generated by discharge of chips is reduced, and the resistance to welding with chips is improved. From the above, the formation of built-up edges is greatly reduced, the sharpness of the drill is less likely to deteriorate, and the life of the drill is greatly increased. FIG. 2 shows the workpiece after machining with the step drill l.

When selecting the cutting conditions for the tool, set the cutting speed faster than the standard conditions (if you do so, the machining efficiency will improve, but the life until re-grinding will be shortened, and if you place emphasis on the tool life, the machining efficiency will be poor). Furthermore, if the cutting speed becomes too low, the drill blade surface will escape and cutting will become impossible.

FIG. 3 shows an example of experimental results regarding the relationship between cutting speed and the number of holes drilled. FIG. 3 also shows the number of holes drilled by an untreated drill 6 and a nitrogen ion implantation drill 7 as a comparative example. 8 indicates the life of the drill. Cutting conditions in this case! ! ! Shown in 1.

! ! ! 1 Here, if we compare the same number of holes and take that as the lifespan, the ion-implanted drill 7 has the same lifespan 8 as the untreated drill 6 even at about twice the cutting speed.

From the above experimental results, even in cutting tools with multiple functions such as sub-land drills, step drills, or center drills, such as seat (zero hole drilling, double chamfering and drilling, or double hole drilling), By injecting nitrogen ions into the cutting edge part with a large outer diameter, even if the cutting process is performed under the same cutting conditions as the cutting edge part with a small outer diameter, the wear on each part will be the same, resulting in efficient machining. be able to.

〔Effect of the invention〕

According to the present invention, a subland drill, a step drill,
Or, in a cutting tool with multiple machining functions such as a center drill, apply the same rotation speed as the small diameter part using a drilling machine etc. to the large diameter part where the cutting speed is inevitably 1+\11・l. be able to.

- From the above two points, cutting can be carried out efficiently and the life of the tool can be greatly increased.

[Brief explanation of the drawing]

Fig. 1 is a front view of a drill showing an embodiment of the method for extending the life of a compound cutting tool according to the present invention, Fig. 2 is a cross-sectional view of a workpiece after machining with a drill, and Fig. 3 is a diagram showing cutting speed and hole drilling. It is a diagram showing the experimental results of the number of pieces. ■・・・Step drill (compound cutting tool), 2.
...Large diameter machining section, 3...Small diameter machining section, 4...
...Ion, 5... Workpiece after processing, 6...
...Untreated drill, 7...Ion implantation drill, 8...Drill lifespan representative, patent attorney
Masaru Ogawa Male Male Female Figure 2, 5

Claims (1)

[Claims] 1. A method for extending the life of a composite cutting tool, which comprises forming a hard coating on the surface of the large-diameter machining section by ion implantation, in the composite cutting tool having a large-diameter machining section and a small-diameter machining section.