KR100423762B1 - Molding method of helical gear - Google Patents

Abstract

The present invention is a shearing process for cutting a metal rod into a suitable size in order to produce a large amount of high-precision helical gear by cold extrusion of alloy steel, and forming the metal material cut in the shearing process through each spur gear and helical gear mold It implements a high precision helical gear forming method consisting of an extrusion process and a finishing process of removing unnecessary parts and surface treatment in the extruded molded article.

Description

Molding method for mass production of high-precision helical gears. {MOLDING METHOD OF HELICAL GEAR}

The present invention relates to a method of forming a helical gear, and more particularly, to a molding method capable of producing a high-precision helical gear in large quantities by separately manufacturing a spur gear mold and a helical gear mold.

Usually, the manufacturing method of a gear can be divided roughly into a cutting method and a non-cutting method. There are various methods of cutting, such as hobbing and gear saving, but automotive gears are generally processed by hobbing, then shaving, and burnishing or lapping. Non-cutting methods include gear casting methods and gear forming methods by plastic processing using metal forming processes such as powder metallurgy, forging, rolling and extrusion. Gear casting methods are disadvantageous in terms of quality and productivity. The method of forming a gear by suitable plastic working is actively researching a new analysis method for manufacturing a high precision gear.

Examples of the gear forming method by plastic processing include cold extrusion, precision forging, warm forging and powder metallurgy, and the like for cold extrusion to form spur gears and helical gears that require minimal finishing in these processing methods. Much attention has been gathered and research has begun.

On the other hand, the conventional manufacturing method for manufacturing high-precision helical gear has the plastic processing stress applied to the teeth and material of the extruded die die in the die insert portion where the maximum shear stress is applied through the continuous mold in the direction consistent with the extrusion direction. Since it works without forming a constant lead angle, a large molding pressure is required, and accordingly, the mold is unreasonable, and thus the stability of the mold is unreliable. In addition, the initial part of the product is damaged due to large processing stress, high friction heat is generated due to excessive friction and resistance stress, and a precise product is not obtained, and also the extrusion speed is low, so that mass production is difficult.

On the other hand, in Korean Patent Publication No. 207441, in a conventional helical gear manufacturing method, first, a spur gear is formed in an extrusion die having different helix angles therein and then formed as a helical gear as extrusion proceeds. The manufacturing method of the high precision helical gear by cold extrusion of the alloy steel which characterized the process has been disclosed.

This prior application registration is to be extruded while being molded in the extrusion flow direction of the metal in the die insert to reduce the shear stress applied to the mold in accordance with the extrusion process to improve the stability of the mold and to obtain a more precise product of the conventional helical gear Clearly, it is useful in its own way compared to the manufacturing method.

However, this registration invention has some improvement in gear grade, but after forming up to 20 helical gears, the mold is damaged, which is not practical and is not utilized in the industry. Patent Publication No. 1992-16165 discloses a method and a mold apparatus for molding a helical gear by using a single mold, as described above. Since the helix angle for spur gears and helical gears is formed in one mold itself in one mold, after forming up to 20 helical gears, mold breakage occurs and due to excessive friction and resistance stress High frictional heat is generated, which makes it impossible to obtain precise products. Especially, low extrusion speed makes mass production difficult. There was a problem.

Accordingly, an object of the present invention for solving the above problems is to manufacture a spur gear mold and a helical gear mold separately, and then first form a spur gear in the spur gear mold, and then manufacture the helical gear mold separately. It is another object of the present invention to design a mold in consideration of the elastic deformation of the mold and the elastic recovery of the material and to process the mold by a precise machining method to gear grade It is to provide a method of forming a helical gear that can be improved and mass produced.

Another object of the present invention is to provide a method capable of mass production and forming a highly accurate helical gear.

The present invention according to the first aspect for achieving the above object is a shearing process for cutting a metal rod into a suitable size in order to produce a large amount of high-precision helical gear by cold extrusion of alloy steel and the cutting process A high precision helical gear molding method is realized, which comprises an extrusion molding process for forming a metal material through each spur gear and a helical gear mold and a finishing process for removing unnecessary parts from the extruded molded article and surface treatment.

Hereinafter, preferred embodiments of the present invention will be described in detail. It should be noted that in the following description, only parts necessary for understanding the present invention will be described, and descriptions of other parts will be omitted so as not to distract from the gist of the present invention.

First, the present invention embodied in the present invention is a method for forming a high-precision helical gear by cold extrusion of alloy steel, preferably forming a primary gear for forming a spur gear and a helical gear having a predetermined angle. As a method of making and molding a secondary mold separately, unlike the prior art, the uneven shape is formed in the same direction as the flow direction on the die insert portion of the spur gear mold which exerts the greatest extrusion stress on the metal material. It is intended to produce a helical gear by molding the teeth and molding the molded teeth to have a predetermined spiral angle through the helical gear mold. For this purpose, the theoretical analysis is conducted by inducing dynamic available speed field that can be applied when extruded from spur gear shape to helical shape, and the process is improved to produce molds of spur gear and helical shape, and to test prototypes. Experiments were conducted to study the formability of torsional extrusion and a series of processing methods.

Hereinafter, the present invention will be described in detail based on the preferred embodiment of the present invention, but the present invention is not limited to the embodiment.

{Example 1}

First, the spur gear mold and the helical gear mold are separately manufactured, and then irregularities are formed in the flow direction in the extrusion process through the molds of the spur gears, and then the teeth and pitches are formed on the irregularities of the metal material, and then continue. The roots were molded. Subsequently, the material having undergone the above-described process is molded through the mold of the helical gear, preferably, the spur gear teeth formed in the flow direction through the mold of the helical gear form a predetermined spiral angle, knocked out, and then the extruded helical. In the finishing process, the helical gear was formed by surface finishing such as finishing and carburizing.

That is, the first material was molded into a spur gear prior to the helical gear to be made first as the extrusion proceeds, and then formed into a helical gear having a spiral angle to be made by torsion through the aforementioned helical gear mold.

On the other hand, the present invention for the above-mentioned forming method is derived from the theoretical analysis of the helical gear cold extrusion die strength analysis and failure analysis by inducing a dynamic available speed field that can be applied when twisting from a flat gear shape to any shape After the mold was examined for damage and life, the mold was designed and manufactured, and a helical gear capable of high precision and mass production was manufactured through extrusion experiments.

Here, if the load acting on the helical gear mold among the helical gear mold and spur gear mold separately manufactured to implement the helical gear forming method of the present invention is calculated as follows.

{Equation 1}

Velocity discontinuity on velocity Z continuous line Z = 0

The energy required here

here Assumes that the spur gear is twisted with the same shape as the part where it is twisted by the herical gear or the part without teeth.

Find Random in

silver from Obtain until. ( )

Is Obtain until.

With each of the above Obtain

= ① + ② + ③

here, To decide Till In equal parts Calculate

中 中 W is the length of the helical gear land part of the mold.

Accordingly, when the helical gear is formed by separately manufacturing the spur gear mold and the helical gear mold as in the present invention, the mold failure caused by the shear stress, which is a conventional problem, can be prevented. In particular, even if the mold is used repeatedly for several times, the mold is not broken and a large amount of helical gears can be produced.

As described above, the present invention solves the problems of the prior art described above, and can realize the stability of the mold by reducing the shear stress acting on the mold, in particular the synergistic that can produce a large amount of high-precision helical gear It works.

Claims (1)

In the method of forming the helical gear, A first process of separately manufacturing a primary mold for forming a spur gear and a secondary mold for forming a helical gear having a predetermined angle from the spur gear formed by the primary mold; After forming the unevenness of the metal material to be made into the helical gear in the same direction as the flow direction in the extrusion molding process through the primary mold, forming the tip and the pitch on the uneven portion of the metal material, and then forming the root again A second process of making a plain word; The third process is to form a helical gear having a predetermined helix angle in the teeth of the spur gear having the second process through the second mold, and to knock out the surface of the extruded helical gear to produce a highly accurate helical gear. Forming method for mass production of helical gears characterized in that.