JPH0576982A - Formation of inner gear - Google Patents

Abstract

(57) [Summary] [Purpose] To simplify the manufacturing process by forming only by cold plastic working, improve yield and increase strength. [Structure] A disk-shaped forming material W having a required shape is obtained from a plate-shaped material from the mass of an internal gear to be formed. Then, it is sandwiched between the molding die 1 and the upper die 2 and rotated at the required number of rotations. While pressing a plurality of molding rollers 3 arranged in an annular shape concentric with the center of rotation of the molding die 1 on the molding material W by equalizing pressure,
Cold plastic pressure is applied by moving along the molding die.
Using the internal stress generated in this molding process, the molded product W0
For higher strength.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing an internal gear in which the internal stress generated by cold plastic working is used to increase the strength of a material and the yield of the material used is improved.

[0002]

2. Description of the Related Art When manufacturing an internal gear as shown in FIG.
As shown in FIG. 4, a steel material W1 cut into a required size is heated to a required temperature, and hot or warm forged to form an internal gear shape W2, and then an inner peripheral surface of the material. The inner teeth are machined to form a finished product W3.

[0003]

Therefore, in the conventional processing method, it is necessary to heat the material to a temperature required for hot or warm forging, and further, forging and mechanical processing are required in the processing step. After machining, a heat treatment process is additionally required to increase the strength of the product, which increases the number of manufacturing processes and causes a problem that the yield of used steel materials is poor.

It is an object of the present invention to simplify the manufacturing process by forming only by cold plastic working, improve yield and increase strength.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to achieve the above object, and a disk-shaped forming material of a required shape is obtained from a plate-shaped material from the mass of an internal gear to be formed, and the required rotational speed is obtained. While sandwiching it between a molding die and an upper die that rotate at a pressure of a plurality of molding rollers arranged in an annular shape concentric with the center of rotation of the molding die, the molding material is pressed against the molding material by pressure equalization. The gist is that cold plastic pressure is applied while moving along the mold, and the internal stress generated in this molding process is used to increase the strength of the molded product.

[0006]

[Operation] A disk-shaped molding material having the thickness and diameter of a flat plate material used from the mass of the internal gear calculated in advance is used as the lower mold for the internal gear molding die, and the upper and lower molds are sandwiched by pressure Then
While rotating the molding die at a predetermined number of rotations, a plurality of molding rollers are pressed from the outer peripheral portion and moved along the longitudinal direction of the molding die. As a result, the disk-shaped material is cold plastically worked. The internal stress generated during this processing increases the strength of the material. Moreover, since the material mass is adjusted in advance to the molded product, the yield is 100% or close to 100%. Further, since the product is manufactured only by cold plastic working, the manufacturing process is simplified.

[0007]

The present invention will be described below with reference to the illustrated embodiments. Internal gear with an outer diameter of 100 to 170 mm has a plate thickness of 4.0 to
When forming using a 6.5 mm plate-shaped material, a plate-shaped material having this plate thickness is manufactured into a disk shape having a diameter calculated from the mass of the internal gear calculated in advance according to the material thickness, and this is called the forming material W. To do.

Next, the molding material W is sandwiched between the lower mold 1 and the upper mold 2. The lower die 1 is a molding die, and a tooth profile 1H is formed on the diameter and size of the internal gear to be formed and on the outer peripheral surface of the die. The upper die 2 supports substantially the central portion of the molding material W placed at a predetermined position on the top plane of the lower die 1, that is, the upper and lower dies are arranged on the same rotary shaft and are clamped and supported. Also has a small diameter. The pressure for sandwiching the forming material W between the upper and lower molds 1 and 2 is determined so as to be firmly supported even when the lower mold 1 is rotated and the forming material is subjected to cold plastic working by the forming roller. The size is about 80 to 100 KN.

At the outer peripheral position of the lower mold 1, two to a plurality of molding rollers 3 are arranged at substantially equal intervals. The molding rollers 3, 3 ... Have the same shape and size, are arranged in the radial direction of the lower mold 1 and are equally spaced from the center of rotation of the lower mold 1, and are rotatably supported. ..

Next, all of the forming rollers 3 are pressed against the outer peripheral surface of the lower mold 1 with the same pressure, which is perpendicular to the rotation of the lower mold 1 and is pressed with a pressure of about 30 KN. Then, while rotating the molding material W sandwiched between the upper and lower molds 1 and 2 at 600 to 1000 revolutions per minute together with the molds, the molding rollers 3, 3 ... Further, the lower die is moved to the outer peripheral position of the lower end of the lower die in the longitudinal direction of the lower die at a feed rate of about 0.2 m / min. This forming roller 3
The movement power of is 30 KN.

In this way, when cold plastic working is performed by a combination of the rotation of the forming material W sandwiched between the upper and lower molds and the pressing movement of the forming roller, and when continuously forming into a cup shape,
The inner teeth are simultaneously molded according to the outer peripheral surface shape of the molding die. At this time, the pressing force of the forming roller is kept constant, and is controlled by CNC control in order to adjust the outer peripheral shape of the internal gear. Since this forming roller 3 follows the rotation of the material, the outer periphery of the forming roller and the lower die is controlled. The peripheral velocities of the outer peripheral surface of the molding material formed by the surface are equal, and the peripheral velocity is 30 per minute.
0 to 550 m is suitable.

Further, in the present invention, since the purpose is to increase the strength by cold plastic working, heat generation during pressure molding is prevented, and because of lubrication between the molding roller and the material, a coolant is used during molding. Is sprayed at a predetermined pressure.

In this way, the internal gear is formed by cold forging while increasing the strength of the forming material W by cold plastic working. The clamping force of the material between the upper and lower molds, the rotation speed and the forming process. The pressing force and the moving pressure of the roller are appropriately selected depending on the type of molding material, the size and shape of the molded product W0, and the like.

FIG. 2 shows a processing situation at the time of molding according to the present invention. In the figure, T0 is the plate thickness of the material, T1 is the tooth height, and T2 is the rib thickness of the gear outer diameter. At the time of molding, the material is sandwiched between the mold and the pressure roller and continuously cold plastic processed. At this time, the flow of the material forms the teeth in the shape of the mold. Since the thickness is set to T0 = (T1 + T2) / (0.5 to 0.8) in advance, deformation during rotation molding occurs over the entire range of the gear, and it is possible to manufacture a uniform strengthened gear. it can. It should be noted that since excess material generated during tooth formation is extruded in the feeding direction of the pressure roller, defects such as alignment scratches and continuous processing are less likely to occur.

[0015]

According to the present invention, since the forming material is evenly formed by the forming roller by press forming, that is, the inner tooth portion is formed by cold plastic working, according to the present invention, the metal portion is formed in the tooth portion. The teeth are pressure-molded uniformly without breaking the flow, the tooth dimensions are accurate, and the effective tooth height can be obtained even if the tooth height is lowered. Can be reduced. In addition, since the entire tooth forming part is pressed uniformly and continuously, the tooth part strength is 1.3% of that of the base material.
In addition to being able to double the strength and achieve higher strength, it has the advantages of concentricity and roundness of each dimension of the tooth part and outer circumference because it is rotational molding, and further the molding process is extremely simplified. ..

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional explanatory view showing a manufacturing process of an internal gear of the present invention.

FIG. 2 is an explanatory diagram showing plastic working of a material in a forming step.

FIG. 3 is an external view showing a partially broken internal gear formed by the molding method of the present invention.

FIG. 4 is an explanatory view showing a conventional molding process.

[Explanation of symbols]

 1 Mold for molding 2 Upper mold 3 Molding roller W Molding material W0 Molded product

Claims (1)

[Claims] 1. A disk-shaped molding material of a required shape is obtained from a plate-shaped material from the mass of an internal gear to be molded, and the disk-shaped molding material is sandwiched between a molding die rotating at a required rotation speed and an upper die, While pressing a plurality of forming rollers concentrically with the center of rotation of the die in an annular shape against the forming material by equalizing pressure, the die is moved along the die to perform cold plastic pressurization. An internal gear molding method characterized in that the strength of the molded product is enhanced by using the internal stress generated as a result.