JPS6325888B2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a pinion cutter for shaping helical gears, and it is possible to replace only the cutter without replacing the helical guide and slider attached to the gear shaping machine. By doing so, it is possible to cut helical gears having any helix angle and any module.

<Prior art> When cutting a helical gear using a conventional gear shaping machine, as shown in FIG. Use pinion cutter 1 in the opposite direction. Further, the cutter shaft 2 to which this pinion cutter 1 is attached is attached to a slider 4 guided by a helical guide 3, and the cutter shaft 2 is attached to a slider 4 guided by a helical guide 3.
performs a spiral reciprocating cutting motion along the spiral groove of the helical guide 3.

Here, the spiral lead L of the helical groove carved in the helical guide 3 is determined by the normal gear module m _o and the helix angle φ determined for the gear material. In other words, the right angle module and helix angle of the pinion cutter 1 attached to the cutter shaft 2 that screws along the helical groove of the helical guide 3 are set to the same value as the value set for the gear material _, respectively. Since φ, the spiral lead L
is given by the following equation (1).

L=m _o・Z・π/sinφ…(1) L: Spiral lead of helical guide (mm) m _o : Right angle module of pinion cutter (mm) Z: Number of teeth of pinion cutter φ: Torsion angle of pinion cutter (degrees) <Problem to be solved by the invention> As is clear from equation (1), when m _o and φ change, in order to keep the spiral lead L at a constant value, the pinion cutter must be adjusted accordingly. It is sufficient to change the number of teeth Z, but since the number of teeth Z is limited to a natural number value, it is possible to keep the spiral lead L at a constant value by changing the number of teeth Z only in special cases. It will be done. Therefore, if the normal gear module m _o or helix angle φ of the conventional gear material changes, the pinion cutter, as well as the helical guide and the slider guided by it, must be replaced with a different one with a different spiral lead L. It was always the case.

However, replacing the helical guide and slider not only takes time but also requires skill for adjustment, which poses a problem that is a major factor in reducing work efficiency. Further, the helical guide and slider themselves are expensive, and it is very uneconomical to have to prepare a large number of them.

The present invention is intended to solve these problems, and aims to provide a pinion cutter that can cut the blades of many types of helical gears with different specifications using one type of helical guide and slider. There is.

<Means for Solving the Problems> A pinion cutter according to the present invention that solves the above problems is installed in a pinion cutter for shaping a helical gear with a right angle module of m _o and a helix angle of φ. When the spiral lead of the helical guide of the gear shaper is L, the number of teeth of the cutter Z _c
is an integer smaller than the value calculated by L・sinφ/m _o・π, the pitch circle diameter d is set to L・tanφ/π, and only one part of the circle pitch is made larger than m _o・π. Features.

<Function> The value calculated by L・sinφ/m _o・π is generally not an integer, but the value after the decimal point is rounded down and the value below the integer is set as the number of teeth of the pinion cutter Z _c . Cut the teeth using the part of the incisor where the circular pitch is m _o π. In the calculation of L・sinφ/m _o・π, by setting L as a fixed value and setting the number of teeth Z _c for any given m _o and φ, one type of L, that is, a helical Various gears with different m _o and φ can be processed without replacing guides and sliders.

<Examples> Hereinafter, the present invention will be specifically explained using examples.

Generally, the number of teeth Z of a pinion cutter is calculated using the previous formula (1).
is expressed by the following equation (2).

Z=L・sinφ/m _o・π …(2) Here, in order to make it possible to cut helical gears of any specifications with one type of helical guide and slider, the spiral lead L is set to a fixed value (constant). Then, as is clear from equation (2), the value of the number of teeth Z may not be an integer due to changes in the right angle module m _o and the torsion angle φ. Here, assuming that there is a gear with a number of teeth that includes a decimal number, and finding the pitch circle diameter d of the pinion cutter, the general formula d=Z・m _o /cosφ...(3) can be expressed as the above ( Substituting the formula 2), we get d=L/πtanφ...(4). That is, the pinion cutter according to the present invention has a pitch circle diameter d given by this equation (3), and has the same normal module _mo and torsion angle φ as the gear material.

By the way, if the spiral lead L is a fixed value,
When forming a pinion cutter as it is with the number of teeth Z calculated using equation (1) from the given tooth right angle module m _o and torsion angle φ, the value of the tooth space is
In some cases, a portion larger than m _o ·π/2 and smaller than m _o ·π may be formed, or a portion with an incomplete tooth profile may be formed. Therefore, in the present invention, the number of teeth Z _c of the pinion cutter is an integer smaller than the value calculated by L・sinφ/m _o・π, that is, if the calculated number of teeth Z includes a decimal, it is rounded down to an integer value or less. Assume that the value of is the number of teeth Z _c of the pinion cutter, and that only one circular pitch is made larger than m _o ·π so that the incisors are missing in that part.

For example, if the number of teeth Z is calculated to be 11.6, then the number of teeth Z _c of the cutter is 11, as shown in Figure 1.
A pinion cutter 6 according to the present invention is formed by arranging 11 incisors 5 having a perfect tooth profile with a circular pitch m _o · π, and making the circular pitch in one place larger than m _o ·π. . In other words, the circular pitch of the part forming the incisor 5 with a perfect tooth profile is equal to the circular pitch of the gear material, and the value is m _o · π, but the complete Only the circular pitch between the incisors 5 has a different value. Of course, generation is also possible by reducing the number of teeth Z _c to 11 or less and cutting the teeth using the complete incisor teeth 5 . The present pinion cutter 6 can be easily manufactured by using an index plate suitable for the design of the pinion cutter 6.

Gear cutting using such a pinion cutter 6 is performed as follows. That is, the present pinion cutter 6 is attached to the cutter shaft 2 of the above-mentioned gear shaping machine, and the generating motion and cutting motion are performed in the conventional manner only at the portion where the cutting teeth 5 are spaced m _o ·π. When the part of the pinion cutter 6 with a different tooth groove value, that is, the part with a large circle pitch, approaches the gear material, move the gear material away from the pinion cutter 6 to prevent the generated rotational movement of both the cutter shaft 2 and the work table. All you have to do is fast forward the tool in reverse, return to the cutting starting point, cut again, and restart the generating motion. Alternatively, when a part with a different tooth space value approaches the gear material, move the work table away from the pinion cutter 6, then rotate the pinion cutter 6 in rapid traverse in the same rotational direction to pass this part and again. It is also possible to continue the generating motion from the incisors 5 whose spacing is equicircular with m _o · π, but in this case, the phase of the points with different tooth groove values is adjusted to the cutter axis 2. It is necessary to make corrections with the work table. These discontinuous rotational movements between the cutter shaft 2 and the work table can be easily performed by setting them in advance when both are driven by NC.

<Effects of the Invention> As explained in detail above, if the pinion cutter of the present invention is used, the pinion cutter can be replaced with a helical gear gear cutter of any specification without changing the spiral lead L of the helical guide. You can do it by yourself. Therefore, there is no need to replace the helical guide and slider, which is troublesome and difficult.
In addition to improving work efficiency, it also contributes to reducing processing costs since there is no need to prepare a large number of expensive helical guides and sliders.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a pinion cutter according to an embodiment of the present invention, and FIG. 2 is a cross-sectional structural view of a cutter head of a general gear shaping machine. In the drawing, 2 is the cutter shaft, 3 is the helical guide,
4 is a slider, 5 is an incisor, and 6 is a pinion cutter.

Claims (1)

[Claims] 1. In a pinion cutter for shaping a helical gear, the right angle module is m _o , the helix angle is φ,
When the spiral lead of the helical guide of the gear shaper to be installed is L, the number of cutter teeth Z _c is an integer smaller than the value calculated by L・sinφ/m _o・π, and the pitch circle diameter d is A pinion cutter characterized in that L・tanφ/π is made larger than m _o・π at only one part of the circular pitch.