JPS6339722A - Assembly hob - Google Patents

Abstract

PURPOSE:To allow the re-coating process of a hob, with a cutting blade assembled in a main body, by using a steel material with a high annealing temperature of the TiN coating process temperature or more as the material for the member such as a hob main body and a collar. CONSTITUTION:A hob main body 2 and a collar 3 are constituted of a material satisfying the requirements among the steel having an annealing temperature higher than the titanium nitride coating process temperature, e.g., low alloy steel such as Cr, Cr-Mo hot working tool steel. As an example, a material containing C 0.35-0.55%, Si 0.15-0.35%, Mn <=0.50%, P <=0.03%, S <=0.03%, Cr 4.2-4.8%, V 0.18-0.23%, Fe remainder, was used. As a result, this assembly hob was re-ground about 30 times, and the re-coating process was repeated, but there was no change in the mechanical characteristics, because the processing temperature of, e.g., 480 deg.C is lower than the annealing temperature of, e.g., 550 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an assembled hob, and particularly to an assembled hob that can be easily recoated.

(Prior Art and Problems to be Solved) Hobs, which are rotary blades having cutting edges on the outer periphery of a cylinder, include assembled hobs and solid hobs.

As shown in FIG. 1, the former assembly hob has a cylindrical hob body 2 with a fitting groove 5 in its axial direction, and a cutting blade 1 having a rack-shaped scoop 4 in the fitting groove. mated,
Both ends of the hob body 2 are fixed with collars 3 and assembled.

By the way, in an assembled hob, the cutting blade 1 is coated with titanium nitride coating before it is assembled into the hob body 2, but once the assembled hob has been used and is worn out, the cutting edge on the rake face 4 will be removed. made and reused. However, in such an assembled hob, the coating layer on the rake face 4 has already been removed due to wear, so naturally,
Crater wear is more likely to progress than in the original case where the coating layer was applied to the rake face 4.

To prevent this, as in the case of coating when making a new product, remove the worn cutting blade 1 from the hob main body 2, apply coating only to the cutting blade 1, and then fit it back into the hob main body 2. It would be fine if they were assembled, but such recoating work is time-consuming and there are restrictions that it can only be carried out by the manufacturer, so currently it is used without recoating.

In this regard, in the case of a solid hob, after cutting the worn hob,
Since the re-coating process is being carried out, it is conceivable that the re-coating process can be performed in the same way in the case of an assembled hob without removing the cutting blade, but in the case of an assembled hob, the hob body 2 and Collar 3 is usually made of a material such as bearing steel, and its tempering temperature is around 300℃, while the TiN coating treatment temperature is 450-55℃.
Since the tempering temperature is 30'C, the tempering temperature is lower than the coating treatment temperature, and as a result, if the hob body is recoated with the cutting blade still assembled, the hardness of the hob body and collar may decrease. Otherwise, there is a problem that distortion occurs and the use as an assembly hob becomes a national liability.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned drawbacks of the prior art, and to provide an assembled hob that can carry out coating processing with the cutting blade still assembled in the hob body, and is particularly suitable for re-coating processing. It is something that is meant to be.

(Means for solving the problem) In order to achieve the purpose described above, the present inventor discovered that the reason why the cutting blade in a conventional assembled hob cannot be recoated while it is embedded is due to the material. In short, by selecting a steel material whose tempering temperature is higher than the TiN coating treatment temperature as the material for parts other than the cutting blade, such as the hob body and collar, hardness reduction and The present invention was made based on the finding that coating treatment can be performed without causing deformation.

The present invention will be explained in detail below based on examples.

As mentioned above, the material of the hob body and collar in the conventional assembled hob is high carbon chromium bearing steel.

For example, SUJ 2 is used. As can be seen from the tempering hardness curve in FIG. 3, in the case of SUJ 2, the tempering temperature is approximately 300° C., although it varies slightly depending on the quenching conditions. On the other hand, the TjN coating treatment of the cutting blade is 4
Since the coating process is carried out at 50 to 530°C, the hob body and collar are subjected to a tempering process, and as a result, it is clear that the mechanical properties change, particularly a decrease in hardness and the occurrence of distortion. It is.

In contrast, in the present invention, a steel material having a tempering temperature equal to or higher than the coating treatment temperature is used as the material for the hob body and collar. Specifically, for example, Cr
A material that satisfies the above requirements is selected from among low alloy steels such as hot work tool steels such as Cv-Mo series and Cv-Mo series. - Examples include C: 0.35-0.55%, Si: 0.
15-0.35%, MnS2.50%, P≦0.030
%, S≦0゜030%, Cr:4.2-4.8%, V:
Some contain O, 18 to 0.23%, and the remainder substantially Fe.

If the material is made of moldable material, even if the assembled hob is re-ground and re-coated about 30 times, there will be no change in mechanical properties as the processing temperature is lower than the tempering temperature, and the hob body and collar will remain intact. Characteristics are maintained. Therefore, it is possible to easily perform the recoating process on the user side as well.

The recoating process can be performed under the same conditions as the initial coating process, and the TiN coating process temperature is usually 450 to 530°C, but even if TiN coating is performed at a higher temperature, the hob If you select a steel material that meets the above requirements for the main body and collar, there will be no problem.

It goes without saying that the shape and structure of the assembled hob are not limited to those illustrated in FIG.

Next, an embodiment of the present invention will be described.

(Example) Using a hob body and collar made of test steel having the chemical composition (wt%) shown in Table 1, the hob body was made of Ti.
After installing the N-coated cutting blade,
Collars were fixed to both ends, and an assembled hob having the shape and dimensions shown in Table 2 was assembled.

This assembled hob was brought into a worn state, and after the blade was sharpened, a recoating process (processing temperature: 480°C) was performed with the cutting blade still installed.

Changes in the hardness of the hob body and collar were examined for the conflict hob before and after recoating, as well as changes in size and shape. The results are shown in Tables 2 and 3. Table 3 also lists the heat treatment conditions (tempering temperature, etc.) for each sample steel, and the tempering hardness curve of sample steel B is shown in FIG. The tempering hardness curve of test steel A is as shown in FIG.

(Left below) From the above results, it was found that the material (sample steel B) that satisfies the requirements of the present invention
), even if the coating treatment was performed with the cutting blade still installed, there was no change in the mechanical properties, shape, or dimensions of the hob body or collar, whereas the conventional hob In the case of an assembled hob using steel (sample steel A), the hardness decreased and the shape 1 dimension changed,
In particular, an investigation into tooth trace errors revealed that the pitch had become smaller.

(Effects of the Invention) As detailed above, according to the present invention, the titanium nitride coating treatment can be performed while the cutting blade remains assembled in the hob main body, so that the assembled hob after wear due to use can be coated with titanium nitride. recoating can be easily performed. Therefore, the number of times the assembled hob can be used can be increased, and re-coating can be performed on the user's side.

Economical. Of course, it goes without saying that this can also be applied on the manufacturer's side when creating a new product.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of an assembled hob, in which (a) is a partial cross-sectional view of the tank, and (b) is a partial longitudinal cross-sectional view. FIGS. 2 and 3 are diagrams showing tempering hardness curves, respectively. 1... Cutting blade, 2... Hob body, 31. , collar, 4... rake face, 5... fitting groove. Patent applicant Takashi Nakamura, Patent attorney representing Kobe 1 Steel Works Co., Ltd. Figure 1 (a) (b) Figure 2

Claims (1)

[Claims] A fitting groove is provided in the axial direction of the cylindrical hob body, and a rack-shaped cutting blade whose surface is coated with titanium nitride is fitted into the fitting groove, and both ends of the hob body are fitted with a collar. 1. An assembled hob, characterized in that the hob body and collar are made of steel having a tempering temperature higher than a titanium nitride coating treatment temperature.