JPS637466Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to a gear-shaped honing tool used for finishing the tooth surfaces of gears with high hardness (HRC50 or higher).

Conventionally, liquid honing or gear-shaped honing stones have been used to finish honing the tooth surfaces of high-hardness gears after heat treatment.
It has been difficult to process leads and pitches with satisfactory accuracy. Furthermore, polishing is also carried out by attaching abrasive grains to the tooth surfaces of a gear-shaped tool, pushing the abrasive grains into a high-hardness gear, meshing with the gear, and rotating the tool. However, due to the relative sliding of the tooth surfaces or the lateral sliding action caused by crossing the axes, the surface layer of the tooth surfaces of the high hardness gear is scraped off by 20 to 40 microns.
In this case, the contact range between the tooth surface of the tool and the tooth surface of the high-hardness gear becomes wider. In other words, since the entire tooth surface is in contact, the contact pressure per unit area is small, and the surface pressure does not increase, resulting in insufficient machinability. Also, since there are no grooves, it is difficult to discharge chips. Furthermore, it is difficult to maintain uniform adhesion of the abrasive grains over the entire tooth surface and to firmly adhere the abrasive grains. For this reason, highly accurate machining could not be expected, and there was also the problem of abrasive grains peeling off.

Furthermore, a grindstone was devised in which the grindstone was formed into a gear shape and the tooth surfaces were provided with serrations similar to those of a shaving cutter. However, the dimensional relationship between the serration width and the land width of the shaving cutter is at most the same size, and in most cases the serration width is larger than the land width. For this reason, during the finishing process of the gear, a large surface pressure per unit area is applied to the narrow land surface, which causes more abrasive grains to fall off, making the overall tooth profile more likely to collapse.
In order to prevent this, it is necessary to reduce the amount of feed to the tool, which leads to a decrease in work efficiency. Moreover, since the entire tool is made of abrasive grains, when re-grinding the land surface of the tooth surface of a grinding wheel such as a diamond grinding wheel, the grinding wheels become clogged with each other, and the tooth surface is formed into a regular involute tooth surface. It is troublesome to do so.

This idea aims to solve these problems by forming a large number of grooves and lands on the tooth surface of a gear-shaped steel gear that has been tempered to a hardness of HRC 35° to 55°.
This invention relates to a gear-shaped honing tool in which abrasive grains such as CBN or diamond, which are hard abrasive grains, are attached to the grooves and lands by means such as electrodeposition.

An embodiment of this invention will be described below with reference to the drawings. In Figs. 1 to 3, the tool body 1 is made of steel and has a cylindrical tooth part 2 around its periphery, and the tooth surface 3 of the tooth part 2 has a serration type. A large number of narrow grooves 4 are provided at uniform intervals, and lands 7 are formed between the grooves. In addition, the structure of the serration grooves and the land width is significantly different from that of a shaving cutter. The tooth surface 3, including this groove, has been tempered in advance to a hardness of HRC 35° to 55° by heat treatment, and diamond abrasive grains 5 are electrodeposited on the entire tooth surface 3 by nickel plating as shown in Fig. 3. There is. In the embodiment of FIG.
2.25, pressure angle 20 degrees, number of teeth 97, helix angle 12 degrees. The tool specifications shown on the left are 1.0 mm in width S of groove 4 and 3.5 mm in width L of land 7. In this invention, the ratio of the width S of the groove 4 to the width L of the land 7 is L/S>
It is set at 1.5. Since L/S<1.00 in a normal shaving cutter, this design has a shape completely opposite to that of a normal shaving cutter. In addition,
In the embodiment described above, the width S of the groove 4 satisfies 0.5 mm<S<1.2 mm, but in other embodiments it may take on a different value. Further, the corner 8 of the land 7 formed on the tooth surface 3 from the tooth tip 6 to the tooth root 9 is rounded or C-chamfered.

When the honing tool of this invention is used, it is meshed with a heat-treated gear (not shown) at a cross-axis angle and rotated with the gear to hone the tooth surface of the gear. At this time, the tool has hard abrasive grains such as diamonds attached to the land on the tooth surface by electrodeposition using nickel plating, etc., and the tooth portion 2 is tempered to HRC 35° to 55° and has appropriate toughness. The contact pressure on the land surface becomes uniform, and the tooth surface of the gear to be machined is ground with diamond abrasive grains, resulting in a highly accurate tooth profile, lead, and pitch. Gear specifications are module 2, pressure angle 20°, face width 20mm, number of teeth 50, helix angle 30° left, material SCr420,
When gears with a hardness of HV700 were machined, no peeling of the abrasive grains was observed even after 100 gears were manufactured, as shown in Figure 4. Here, L/S=0 indicates the one without serration, L/S=0.66 indicates the serration ratio of a normal shaving cutter, and L/S=3.5 indicates the one of the present invention.

As mentioned above, this idea is based on the land on the tooth surface of the gear.
Hard abrasive grains such as CBN or diamond are attached using nickel plating, etc., and a large number of grooves are formed, and the ratio of groove width S to land width L is set to L/S>1.5.
And so. As a result, we were able to obtain the following effects.

I○ Compared to a gear-like tool without serrations with hard abrasive grains attached to the tooth surface, the contact area between the tool and workpiece is reduced and at the same time the surface pressure increases, eliminating the need for large pressing loads, resulting in damage to the machine and tools. It is relatively easy to scrape off.

○ In addition, unlike the normal shaving cutter shape, the land width L is wider than the serration groove S, so the surface pressure per unit area is relatively low, and there is no fear of hard abrasive grains peeling off. Since there is no need to reduce the feed amount, the machining time is also shortened.

Furthermore, since the cutting oil during machining can pass through the grooves on the tooth surface, chips can be discharged smoothly, which is highly effective against clogging that is unique to honing.

○ Since the adhesion area of hard abrasive grains is reduced compared to a gear-shaped one without serrations, it is also effective in making the hard abrasive layer uniform.

Since the corner 10 of the land 7 is chamfered 8 such as R chamfering or C chamfering, the hard abrasive grains from the chamfered part do not fall off, so that a series of hard abrasive grains generated from the corner of the land 7 to the land surface are prevented. Since the honing effect can be prevented from falling off, the honing effect can be further improved and the life of the tool can be extended.

[Brief explanation of the drawing]

Fig. 1 is a front view of an embodiment of this invention, Fig. 2 is a cross-sectional view taken along the - line in Fig. 1, Fig. 3 is an enlarged view of the main part of the tooth part in Fig. 1, and Fig. 4 is an embodiment of this invention. It is a chart showing the results of the number of gears machined. 1...Gear body, 3...Tooth surface, 4...Groove, 5...
...abrasive grain, 7...land, 8...corner, L...land width, S...groove width.

Claims (1)

[Scope of utility model registration request] A gear honing tool that has hard abrasive grains attached to the tooth surface of a steel gear-shaped main body, has a large number of grooves on the tooth surface, the width formed between the grooves is uniform, and the groove The ratio of width S to land width L is L/S>
A gear-shaped honing tool characterized by a diameter of 1.5 and chamfered corners of the land.