JPS5923934B2 - shaving cutlet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improving the cutting performance of a shaving cutter.

As shown in Figure 1, conventional shaving cutters have serrations that form a continuous effective cutting edge that corresponds to the tooth surface from the tip to the root of the gear being cut. The shape, dimensions, etc. of the cutter are uniform in the face width direction of the cutter, and therefore, its cutting performance (so-called sharpness) is uniform within the above-mentioned continuous range.

However, since the cutting conditions during the shaving process are not uniform at each position from the tooth tip to the tooth root of the gear to be cut, the amount of cutting at each position differs. For this reason, it is extremely difficult to obtain a desired tooth profile. In the past, in order to obtain the desired gear tooth profile, the tooth profile of the shaving cutter that corresponds to the desired tooth profile was found empirically, and therefore a lot of effort was required to find the cutter tooth profile and maintain and manage the desired cutter tooth profile. It will require.

Therefore, when considering the reason why the amount of cutting differs at each position of the serration, we considered the commonly used pressure angle of 200.
With regular gears, during shaving, the engagement ratio between the cutter and the gear generally does not reach 2, so there is a 2-tooth tooth engagement on the tooth tip and root sides, but near the standard pitch circle ,1
The teeth are in occlusion.

Therefore, the tooth surface load in the 1-tooth meshing area is higher than the tooth surface load in the 2-tooth meshing area, but as shown in Figure 8, which shows the relationship between pressing force and cutting amount in road shaving, the amount of cutting is Since there is an almost proportional relationship between the pressure and the pressing force, the amount of cutting will be greater near the reference pitch circle where the tooth surface pressure is high than in other areas, and conversely, the amount of cutting will be greater in the vicinity of the reference pitch circle where the tooth surface pressure is high, and on the contrary, on the opposite tooth where the tooth surface pressure is low. On the surface, the amount of cutting decreases, and as shown in FIG. 2, the tooth profile near the reference pitch circle where the tooth surface pressure is high becomes concave.

The present invention eliminates one major and clear cause among the various unexpected causes that cause defects in the distribution of surface pressure inside the contact ellipse applied to the machining part, and attempts to correct the cutter shape by trial and error. The purpose is to provide a shaving cutter that can significantly reduce the work of
In order to increase the cutting performance in the tooth flank meshing area relative to that in the single tooth flank meshing area, the shape of the lands that are lined up in the tooth width direction is changed between lands by moving them toward the center in the tooth width direction. It is characterized by this.

In the present invention, the shapes of the parallel lands in the face width direction change between the lands as they move toward the center in the face width direction. The shape is different, that is, the shape is different between the 1 tooth flank meshing part and the 2 tooth flank meshing part, and the change in shape means that the cutting performance in the 2 tooth flank meshing part is better than that in the 1 tooth flank meshing part. The surface pressure on the contact ellipse is relatively strong, and the depth of cut is relaxed at the point where it should be large, and conversely, the surface pressure on the contact ellipse is increased. The depth of cut is accelerated in places where the depth of cut is relatively weak and should therefore be small, resulting in uniform cutting over the entire area, which is the cause of various defects in surface pressure distribution. Since the major cause can be removed, the trial-and-error work of repairing stubs can be greatly reduced, while also leading to the discovery of other causes.

The present invention will be explained in detail below with reference to Examples.

In Fig. 3, reference numeral 4 denotes a shaping cutter according to the present invention, in which every other land 2 and slit 3 are arranged next to each other in the tooth width direction, and the lands 2 that are arranged next to each other are arranged toward the center in the face width direction. Its shape changes between
In this case, the land width is wider than the left and right sides other than this portion, that is, the one tooth surface meshing portion. There are various ways to make this change, and now the land width/pitch (pitch land width + slit width)
In terms of value, the central part is larger than the other parts, that is, both sides. Therefore, in order to increase this value, either the land width is kept constant and the pitch is made small, the pitch is kept constant and the land width is made large, or the slit width is kept constant and the land width is made large. With such a serration configuration, the part where the cutter and the gear to be cut (referred to as a contact ellipse) mesh with each other is, as shown by diagonal lines in Fig. Since the contact area at the two-tooth meshing part shown in the figure is smaller, even if there is a difference in the tooth surface pressure, the amount of penetration δ between the cutter 4 and the gear to be cut 5 (see C in the figure) is smaller than the one tooth. The surface meshing portion and the two tooth surface meshing portion are the same, the amount of cutting becomes equal, and the recess 6 that conventionally appeared in the one tooth surface meshing portion shown in FIG. 2 disappears.

In the embodiment shown in FIG. 3, the shape that changes in the tooth width direction is the shape on the contact surface or tooth surface, but the embodiment shown in FIG. 4 relates to a change in the three-dimensional shape of the land.

The serration configuration shown in this example is an example in which the rake angle of the cutting edge is made relatively more negative in the one tooth surface meshing part X than in other parts. Note that 7 in the figure indicates the cutter shaft. In addition to the above-mentioned examples, the serration structure may be constructed by making the cutting edge of the serration relatively larger in the area where one tooth engages than in other areas, or by increasing the clearance angle at the area where two tooth flanks engage. Things like this are possible.

Next, in a general case where both the shaping cutter and the gear to be cut have a helix angle, we will discuss how much relative change should be applied to the cutting performance of the shaping cutter.

Figure 5 is a tooth surface correspondence diagram between the cutter and the gear to be machined. In the figure, α is the basic cylindrical helix angle of the cutter, β is the basic cylindrical helix angle of the cutter, and U is one tooth surface. Assuming the engagement line length (see Figure 2), the axial length L of the cutter within the range in which the cutting performance should change relative to the area where two tooth flanks are engaged since it is one tooth flank engagement is as follows. Become.

Alternatively, it may be done by measuring the length Q (see FIG. 2) of the concave portion when processed with a conventional serration cutter.

However, in the above, both R' and R'' are numerical values that can be obtained empirically.If the cutter has a helix angle, the contact ellipse, which is the pressure-receiving surface where the cutter and the gear to be cut come into contact, is the sixth As shown in the figure, since it moves obliquely at an angle of γ, the present invention is applied based on the width range that one tooth flank mesh has in the cutter axis direction on the line along which it moves.

Further, when the helix angle is small or when the cutter is crowned, L becomes small, but the present invention can be easily applied by making the serrations oblique. The meshing area of one tooth surface on the tooth surface of the cutter changes in the tooth height direction as the tooth thickness decreases, but it does not change in the axial direction. Even if the number decreases, there will be no shift in the corresponding position.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing the serration shape of a conventional shaping cutter, FIG. 2 is a shaping tooth profile diagram of a conventional shaping cutter, and FIG. 3 is a perspective view showing the serration shape of a shaping cutter according to the present invention. FIG. 4 is a plan view of the upper end surface seen from the arrow direction W, and FIG. 5 is an explanatory diagram showing the correspondence relationship between the tooth surfaces of the cutter and the gear to be cut, and FIG. 6 is an explanatory diagram showing the movement of the contact ellipse on the tooth surface.
Figures 7A, B, and C are explanatory diagrams showing the contact ellipse diagram at the two-tooth meshing part, the contact ellipse diagram at the one-tooth meshing part, and the bite relationship between the cutter and the gear, and Figure 8 is the cutting amount and pressing force. It is a graph diagram showing the relationship. 1, 4... Shaving cutter, 2...
・Land, 3...Slit, 5...Tooth surface of the gear to be cut, 6...Indentation, 7...Cut axis center line.

Claims (1)

[Claims] 1. In order to increase the cutting performance in the two-tooth meshing area relative to that in the one-tooth meshing area, the shape of the lands that are aligned in the face width direction is changed between lands by moving them toward the center in the face width direction. A shaving cutter that is characterized by: