JPH0360920A - Working method for toothed wheel - Google Patents

Abstract

PURPOSE:To generate no burr on the tooth face and to curtail the manday in working by executing a shot peening on a gear cut toothed wheel after executing an R beveling on a tooth tip edge part simultaneously with the gear cut of the tooth profile to be cut with the execution of gear cutting. CONSTITUTION:A gear cutting is performed by using a hob cutter 8 with a semi-topping having a semi-topping tooth profile 7, an R beveling is executed by an edge part 6 on a tooth tip edge part and an R beveling part 19 is formed. Consequently, a ridge line part is not caused on a tooth face 4 even in case of a shot peening being executed on this gear cut toothed wheel 1 and a burr is not generated at all.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a method for machining cylindrical gears.

Conventional technology and its problems In the mass production process of cylindrical gears, the teeth of gear l are fixed as shown in Figure 3 to prevent the gears from colliding with each other and causing dents due to shock during transportation or reloading. A so-called 45° chamfer is applied to the leading edge (the chamfer is designated by 2).

This chamfering process is performed using a hob cutter 1 with a semi-topping tooth profile 17 formed by forming a chamfering blade part 6 on the tooth base, as shown in FIG.
As shown in Fig. 3, the tooth tip edge where the outer cylindrical surface (tooth tip surface) 3 and the tooth surface 4 of the gear 1 intersect is the blade portion at the same time as the gear cutting of the tooth profile 1a to be cut. 16 to form a chamfered portion 2. 5
is the pitch circle.

On the other hand, shot peening is performed on gears incorporated in, for example, the power transmission system of automobiles in order to improve their strength.

However, the above semi-topping hob cutter 1
When shot peening is applied to the gear 1 which has been subjected to gear cutting in step 8, the ridgeline 9 between the chamfered portion 2 and the tooth surface 4 becomes a ridge 10 due to the impact of shot (steel ball) projection, as shown in FIG. As a result, this streamer 10 causes abnormal noise when gears mesh.

Therefore, as a post-process, finishing processing for the purpose of removing the burrs 10, for example, finishing finishing processing by grinding, is required, resulting in an increase in the number of processing steps.

The present invention was made in view of the above problems.
An object of the present invention is to provide a gear processing method that prevents the occurrence of burrs due to shot peening.

Means for Solving the Problems The present invention performs gear cutting using a hob cutter with semi-topping, which has a rounded chamfering blade portion formed at the root of the tooth, unlike conventional hob cutters. A feature of this method is that at the same time as cutting, the edge of the tooth tip of the workpiece tooth profile is rounded and then shot peened.

According to the present invention, due to round chamfering, the tooth surface of the involute tooth profile of the workpiece tooth profile and the outer peripheral cylindrical surface (tooth tip surface) of the gear are continuous in a smooth curve, so that the ridgeline part unlike the conventional one is formed. does not occur.

As a result, no burrs will occur even if shot peening is applied.

Embodiment FIG. 1 (A) shows the tooth profile of a semi-topping hob cutter 8 used in the present invention, in which the left and right cutting surfaces 11 and 12 of the semi-topping tooth profile 7 and the tooth bottom surface 13 are connected by a smooth curve. This differs from the conventional one in that a round chamfering blade portion 6 with a predetermined curvature is formed at the root of the tooth. The curvature of the blade portion 6 is such that a smooth curve can connect the terminal end 15 of the involute curve of the tooth profile 14 to be cut and the outer cylindrical surface (tooth tip surface) 3 of the gear, as shown in FIG. 1(B). Set to size.

Therefore, when gear cutting is performed using the semi-topping hob cutter 8 having the semi-topping tooth profile 7 shown in FIG. A radius chamfering process is performed by the blade portion 6 to form a radius chamfer portion 19.

After that, even if shot peening is applied to the cut gear 1, the tooth surface 4 will have the ridgeline part 9 (third
(see figure) does not exist, so no streamlining occurs at all.

Here, if the radius of curvature R of the round chamfered portion 19 is too small, burrs will be generated during shot peening as in the conventional case and gear noise will increase, while if the radius of curvature R is too large, the gears will not mesh properly. Since gear noise also increases as the ratio decreases, it is desirable to set the radius of curvature R by selecting a value that minimizes gear noise.

The inventor conducted an experiment on a gear with a module m-=2.5, and the relationship between the gear noise level and the radius of curvature R was as shown in FIG. 2. As is clear from FIG. 2, it depends on where the allowable limit level of gear noise is set, but as far as the gear with module m=2.5 is concerned, the radius of curvature R of the radius chamfer 19 is 0.35≦R/ It is desirable to set it within the range m≦0.2 (where m is the module).

Effects of the Invention As described above, according to the present invention, gear cutting is performed using a hob cutter with semi-topping, which has a rounded chamfering blade portion formed on the tooth base, and the gear cutting of the tooth profile of the workpiece is performed. At the same time, by rounding the tooth tip edge and then applying shot peening to the cut gear, a ridgeline is created on the tooth surface of the workpiece tooth profile unlike the conventional 45° chamfer. Therefore, even if shot peening is performed after gear cutting, no burrs will be generated on the tooth surface. As a result, there is no need for extra finishing processing for the sole purpose of removing burrs, unlike in the past, and the number of processing steps can be reduced.

[Brief Description of the Drawings] Figure 1 (A) is an explanatory view showing the semi-topping tooth profile of the hob cutter used in the present invention, and Figure 1 (B) is the same figure (A).
Explanatory diagrams 1 and 2 of the tooth profile of the workpiece cut by the tooth profile of
The figure is an explanatory diagram showing the relationship between the radius of curvature of the rounded chamfer and gear noise, Figure 3 is an explanatory diagram of a front tooth profile cut by a conventional semi-topping tooth profile, and Figure 4 is the same (conventional semi-topping tooth profile). FIG. 5 is an explanatory diagram showing the situation in which the conventional workpiece tooth profile rises. 1...Gear, 3...Tooth tip, 4...Tooth surface, 6...
・Blade part for tail chamfering, 7... Semi-topping tooth profile, 8... Hob cutter, 13... Tooth bottom surface, 14...
Tooth profile to be cut, 19...R chamfered part. Figure 1 (A) Figure 1 (B) Figure 2 0.7 0.6 0.5 0.4 0.3 Figure 4 Figure 5 Procedural Amendment Statement) ■. Display of the case 1999 Patent Application No. 195115 2゜Name of the invention Gear processing method 3゜4゜Relationship with the case Applicant (399) Nissan Motor Co., Ltd.

Claims (1)

[Claims] (1) Gear cutting is performed using a semi-topping hob cutter with a rounded chamfering blade formed at the root of the tooth, and at the same time the tooth profile is cut, the tooth tip edge is chamfered. A gear processing method characterized by subjecting the cut gear to shot peening.