JPS60166139A - Manufacture of spur gear - Google Patents

Abstract

PURPOSE:To mass-produce spur gears high in tooth form accuracy by forming a lubrication film made of water-soluble lubricating agent solution on a descaled and heated plank having required size, heating this film in high frequency and performing precision die forging. CONSTITUTION:A round bar steel material having a diameter equivalent to 65- 100% of the root diameter of a spur gear to be manufactured is cut to specified length and descale this product to form a plank. This plank is heated at a temperature range of 100-200 deg.C, immersed in an water-soluble lubricant solution. After forming a lubricating film on the surface, heated to a temperature range of 650-900 deg.C by high frequency heating, and precision die forged products are obtained. Thus, mass production of spur gears of high tooth form accuracy becomes possible by eliminating generation of scales and omitting gear cutting process.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a spur gear in which precision die forging is performed by warm forging and a gear cutting process is omitted.

High-precision spur gears with gear accuracy of JIS grade 4 or higher used for automobiles, etc. are rolled material → hot forging → tempering and annealing) → machining → gear cutting → carburizing and quenching, tempering → lapping It was made using the manufacturing process.

As mentioned above, machining and gear cutting processes were required after hot forging. In the machining and gear cutting processes mentioned above, scale is generated after hot forging, so it is not possible to finish to precise dimensions by hot forging. After hot forging, it was finished to precise dimensions by machining and gear cutting.

However, when these machining and gear cutting steps are involved, the production cost becomes high, which is disadvantageous for mass production.

In view of the current situation, this invention utilizes warm forging, which has the advantages of both cold forging, which has the advantage of no scale generation and high precision, and hot working, which has the advantage of obtaining high deformability under low load. This paper proposes a method for manufacturing high-precision spur gears that eliminates the gear cutting process.

That is, the present invention uses a blank obtained by cutting a round steel bar having a diameter of 65 inches or more and less than 100 inches to a required length and removing scale from the root diameter of the spur gear to be manufactured. After heating to a temperature range of 200°C and soaking in a water-soluble lubricant solution to form a lubricant film on the blank surface,
The gist is to manufacture spur gears by heating to a temperature range of 650 to 900''C using high frequency heating and performing precision die forging.

In this invention, the diameter of the blank needs to be smaller than the root diameter of the spur gear in order to fit it into the hole of the forging die, but if it is less than 65% of the root diameter, there will be a lack of thickness in the tooth crest of the gear. Therefore, it is set to 65% or more and less than 100% of the spur gear root diameter.

The blank temperature during immersion in the water-soluble lubricant solution is 100
Below °C, the r1 synovial membrane dries poorly; on the other hand, at 200 °C
If the temperature exceeds this temperature, the lubricant will adhere in the form of bubbles and a sufficiently uniform film cannot be formed, so the heating temperature of the blank was set in the range of 100 to 200°C.

Heating during precision die forging requires rapid heating to suppress the formation of scale and to process economically, and therefore it is desirable to use high frequency heating.

In addition, if the heating temperature at that time is less than 650°C, the deformability will be low, the forging load will be high, and the effects of processing will remain on the product, which is not preferable. On the other hand, if the temperature exceeds 900°C, scale formation is observed, and the tooth profile precision IW of the product decreases. Therefore, the temperature range was limited to 650 to 900°C.

Although colloidal gutsphite is generally used as a lubricant for warm forging, a water-soluble carbon lubricant is also used in this invention.

Next, embodiments of the invention will be described.

A round steel bar having a diameter of 65 to 100 inches relative to the root diameter (Do) of the spur gear to be manufactured is cut into a required length and subjected to shot blasting or pickling to remove scale and produce a blank.

At this time, in order to prevent the corner portions of the blank from forming folding flaws during die forging, the corner portions may be chamfered by grinding, cutting, or forging.

In addition, if a round steel bar is cut using a normal shear cutting method, the blank will be deformed and the end face will sag, so it is necessary to lubricate the blank and modify the shape by forging separately, which increases costs. Therefore, it is desirable to perform one-piece cutting or restraint shear cutting.

A water-soluble lubricant solution previously stored in a storage tank by heating the blank to a temperature of 100 to 200"C in a heating furnace,
For example, White Lube (trade name of Taihei Chemical Products), Delta 7
The blank is immersed in Oji 144 (trade name, manufactured by Acheson Japan) to form a lubricating film with a thickness of about 5 to 20 μm on the blank surface.

Then, by high frequency heating, for example, 200"C/min
The heated blank is rapidly heated to a temperature range of 650 to 900 ° C at the above heating rate, and warm precision forging is performed by charging the heated blank into a mold set in a forging machine such as a clamp press. The molded product is removed from the mold and air cooled.

In addition, if the blank is made of a material with high hardenability, air cooling will cause the material to harden and harden, causing problems with tool life in the subsequent cutting and shaving processes, so in this case slow cooling is required. . Gradual cooling is also effective in preventing grain coarsening during carburizing.

EXAMPLE Spur gear A shown in FIG. 1 and spur gear B shown in FIG. 2 were finished by warm precision forging using the blanks shown in Table 1 under the forging conditions shown in the same table.

Table 1: According to the manufacturing method described above, the tooth profile accuracy was measured when 500 pieces were forged and when 7000 pieces were forged. The results are shown in Tables 2 and 3.

From Table 2 above, it can be seen that when 500 pieces were forged, all of them achieved good results above grade 4 in terms of JIS overall accuracy. Further, as shown in Table 3, the tooth profile accuracy when forging 7000 pieces is slightly inferior to when forging 500 pieces, but by shaving, it is possible to easily maintain high accuracy equal to or higher than JISA grade.

As described above, by performing warm forging, this invention can mass-produce spur gears with high tooth profile accuracy, and can significantly reduce production costs by omitting the gear cutting process.

[Brief explanation of the drawing]

1 and 2 are longitudinal cross-sectional views of spur gears manufactured according to the present invention. D...outer diameter, Do...trough diameter, T...thickness. Applicant Sumitomo Metal Industries Co., Ltd. Sumikin Seisatsu Co., Ltd. Figure 1 Figure 2 Voluntary procedure amendment May 16, 1980 1. Case description 1988 Patent layer No. 23240 2. Name of invention Spur gear Manufacturing method 3, relationship with the amended case Applicant #4, 5-15 Kitahama, Higashi-ku, Osaka (211) Sumitomo Metal Industries, Ltd. (and one other person) 4, Agent 3, Ginza, Chuo-ku, Tokyo -3-12 Ginza Building (561-53
86.0274) (7390) Pressed by the Patent Attorney 1) Yoshihisa 5, dated 1939, month, day 1, the process chart figure on the left side of the drawing attached to the specification of the present application is deleted and amended as shown in the attached drawing. List of attached documents (1) Amended drawings (1 copy, Figure 1)

Claims (1)

[Claims] A blank obtained by cutting a round steel bar having a diameter of 65q6 or more and less than 100cm to the required length and removing scale from the root diameter of the spur gear to be manufactured is heated to 100~200''C.
The blank is heated to a temperature range of
A method for manufacturing a spur gear, characterized by performing precision die forging by heating to a temperature range of 50 to 900°C.