JPS61235033A - Production of gear wheel - Google Patents

Abstract

PURPOSE:To increase the accuracy in gear wheel and to reduce the cost by punching a shaft hole as well as by forming a gear wheel integrally by hot forging, then by moving the wall of the outer peripheral part of the shaft hole in the cold coining stage. CONSTITUTION:An upset blank FW is formed by subjecting to plastic work with hot forging by heating the blank which is cut in the necessary length. The gear profiling face is then formed integrally via one time or plural times of forging stage by fitting the blank FW into the closed forging die. In this case the tooth profile 1 is formed somewhat smaller than the set tooth profile 2. A shaft hole 3 is then made on the blank FW with smaller diameter than the set bore diameter to let the shaft hole part has an excess metal part. A punch 6 is forcibly fitted into the shaft hole 3 in the cold coining stage. With this method the tooth profile 2 is formed by moving the excess metal part 7 of the shaft hole inner peripheral part. The tooth profile flaw in not caused because of no ironing stage being performed. The gear accuracy is therefore increased and the cost reduced as well.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a method for manufacturing gears for automobiles, agricultural machinery, and other general use, in which highly accurate products can be obtained through a forging process only. It is.

[-Conventional technology and its problems]

Conventional gear manufacturing methods include manufacturing by direct cutting from the material, and forming teeth by hot forging the material into the desired shape and then machining (cutting) the first tooth formation position. There is. However, either of these methods requires a process of cutting the material and has the drawback of high costs. In order to improve this problem, a method of manufacturing gears by forging has been proposed in recent years.

In this forging method, the material is first hot-forged to form a tooth profile with a hole slightly larger than the predetermined size, and then the tooth profile is squeezed from the outside in a so-called cold coining process. It is molded into the tooth profile with the required precision. Therefore, in this well-known forging method, scratches occur during the ironing process, and in order to remove these scratches, the root portions of the teeth, that is, the scratched portions, are cut by machining in a subsequent process. For this reason, a cutting process is required to remove the scratches, and the roots of the teeth cannot be effectively used for power transmission. Taking this into consideration, the gears are shaped slightly larger in the longitudinal direction.

[Means for solving problems]

The present invention has been made in order to eliminate the above-mentioned drawbacks, and is forged by hot forging or warm forging to have a desired tooth shape at a predetermined position to form a gear. Next, a shaft hole with a diameter smaller than the shaft hole diameter set at the center is extracted, and after the material is cooled, the material on the outer circumference of the shaft hole is moved toward the outer circumference in a cold coining process, and the desired shape is formed. It is characterized by manufacturing gears with a precision of forging.

〔Example〕

The present invention will be explained below based on embodiments shown in the drawings.

A steel material, generally a bar-shaped material, that can be used as a gear is cut to a size suitable for the size, shape, diameter, etc. of the gear to be manufactured. The raw material W cut to the required length is then heated at a heating temperature determined according to the type, size, weight, etc. of the raw material so that the temperature is suitable for hot forging, that is, plastic working. The heated material HW is upset-formed by hot forging, that is, plastic working, in an upsetting step to match the shape of the gear to be formed. In this case, the upsetting outer diameter is matched to the outer diameter of the gear to be manufactured so as to be suitable for the next step of plastic working.

Next, this upholstered material F'W is placed in a closed forging mold and a tooth profile is integrally formed on the tooth forming surface through one or more steps. Tooth profile 1 formed in this closed forging die is formed to be slightly smaller than set tooth profile 2, and this difference is used to ensure that the tooth profile has a predetermined accuracy in the subsequent cold coining process. It is usually set appropriately in the range of 0.3 to 0.03. In the next step, a shaft hole 3 is bored in the material FW on which the tooth profile 1 is formed. In this case as well, the diameter of the shaft hole 3 is made smaller than the set shaft hole diameter, and the shaft hole portion is provided with an extra thickness. After this drilling step, if necessary, other necessary post-treatment steps, such as standard one-shot blasting, may be performed.

The material F'W with the tooth profile formed in advance in this manner is then sent to a cold coining process. This cold coining is carried out using, for example, a mold as shown in No. 4gJ. An upper mold 4 and a lower mold 5 are vertically opposed to form a gear with the precision to be molded. Material pwf with the tooth profile formed inside this upper and lower mold 4°5: Tapered shaft hole 3 that is fitted and drilled in a hot process
Forcefully insert the tapered punch 6 inside. At this time, by forcefully inserting the punch 6, the extra wall portion 7 on the inner periphery of the shaft hole is pushed out toward the outer periphery of the material, and through this cold coining process, the small tooth profile 1 formed by hot forging is coined. A tooth profile 2 of a predetermined size is formed using a mold 4.5. Furthermore, if the amount of extra thickness on the outer periphery of the shaft hole is larger than the amount of molded tooth profile, the mold 4.5 may be subjected to a pressure higher than the set value, causing damage. In order to prevent this, 1) In order to release the excess extrusion of this material, a slight gap 9 and a burr 10 may be formed in the hole between the tip of the boss 8 that is continuous with the teeth of the mold 5 and the mold bottom. .

〔Effect of the invention〕

In the conventional manufacturing method, in which the tooth profile to be formed is previously formed into a larger size than the set size by hot forging, and then squeezed from the outside in the next cold coining process, scratches occur during the ironing process, but in the present invention, the tooth profile is It is made small in advance, and during the coining process, the excess material inside the shaft hole side is plastically processed to the outside of the material to form it to the required dimensions, so there is no ironing process and therefore no scratches occur. Therefore, the molded tooth can be effectively used over its entire length, and has the advantage that no machining is required after coining.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing the manufacturing process of the present invention, Fig. 2 is an illustration of an example of the product, Fig. 3 is an explanatory diagram of the hot forging process, and Fig. 4 is an explanatory diagram of the cold coining process. . W is the material, HW, FW are the materials, 1 is the tooth profile to be molded, 2
is the set tooth profile, 3 is the shaft hole, 4 is the upper mold, 5 is the lower mold, 6
is the punch, 7 is the extra meat, 8 is the boss, 9 is the gap, and 10 is the paris. Patent applicant: Goto Forging Co., Ltd.1? Agent Ike 1) Manki: Raw 1j-r, -;
, ! Outside 1: Name-1' (1) 1st (4') (5) Figure 3 L' Figure 4

Claims (1)

[Claims] The material is cut to the required size and then hot forged to form a gear with the required tooth shape at a predetermined position. A method for producing a gear, which comprises: punching out a shaft hole, cooling the material, moving the meat on the outer periphery of the shaft hole toward the outer periphery in a cold coining process, and manufacturing a gear with desired accuracy by forging. .