JPS62179844A - Forming metallic die for timing belt pulley - Google Patents

Abstract

PURPOSE:To improve the strength and accuracy of a product, and also, to execute efficiently a production by forming a tooth form crest part and a trough part of a die to a roundish projecting shape, and also, setting a divided position of a punch to a corner R part of a tooth crest of a product. CONSTITUTION:A roundish projecting shape M is provided on both shoulder parts of a tooth form crest part of a die 2, so that it is suppressed that a material of a part D flows in the direction A, and also, a material of a tooth crest top part 1a flows easily into the part D. A punch divided position 3a is set in the vicinity of the tooth crest corner D, so that a punch 3 can move easily in the radial direction of the punch 3. By using a metallic die which has been constituted in this way, the strength and accuracy of a product can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a mold for forming a timing bell 1-pulley.

(Prior art) A timing belt pulley made of metal is a pulley with rounded (R toothed) teeth on the outer periphery, and is used to hang a timing belt.
When forming the tooth profile of the pulley using a mold, the circumferential length after forming the tooth profile is approximately 1.45 times the circumference of the product's outer diameter, resulting in local elongation of the plate. There were 71 points where the strength was slightly reduced and the shape accuracy such as bending radius could not be ensured, so conventionally the molding was done by rolling) Δ.

However, according to this rolling molding, the roughness of the product is 1.
]\γ et al., there were inconveniences such as undulations occurring on the south side, which took time to adjust the rolling machine, and continuous application for a long period of time caused variations in the accuracy of external dimensions, etc.

[Problems that the invention attempts to solve]

The present invention was made in order to solve the above-mentioned conventional problems, and it is an object of the present invention to provide a mold for forming a timing bell l-pulley, which improves manufacturing efficiency, precision, and quality. be.

[Means for solving problems]

In order to solve the problem, the present invention involves adding a die to the inside of a semi-finished product that has been formed into a rough tooth shape by adding excess thickness to the outer periphery of a cylindrical drum in the previous process, and a plurality of punches radially outward. The die has a rounded convex shape at both n parts of the tooth profile crest and the center of the tooth profile valley, and the division position of the punch, which has a shape that matches the regular tooth profile, is at the 8th corner of the product tooth profile. The gist of this invention is a molding die that can press a timing belt pulley that shifts the regular R tooth profile to the right by relative movement of the die and punch in the radial direction.

〔Example〕

Hereinafter, the molding die of the present invention will be specifically explained with reference to illustrated examples. Figure 3 shows a semi-finished product that has been formed into a rough tooth shape by providing excess thickness on the outer periphery of the cylindrical drum in the previous process, and as shown in Figure 1, the die 2 placed inside and the outside of the semi-finished product. By the relative movement of a plurality of punches 3 arranged radially,
The semi-finished product 1 is forged into a regular R tooth shape, but at this time, the plate elongation at the tooth corner D portion is suppressed as much as possible to form the corner R.
It is necessary to take care not to increase the forging pressure, and to ensure that the forging load is applied to the peaks and valleys C, which have been relatively largely elongated in the previous process.

Therefore, as shown in FIG. 1, a rounded convex shape M is provided on both shoulders of the toothed ridge portion of the die 2 used for main molding to suppress the flow of the material in the rounded portion in the direction of the arrow. The corner radius of the D part can be easily secured by making it easier for the material of the tooth ridge top part 1a that is under pressure to flow into the D part, and furthermore, a rounded convex shape is formed in the center of the tooth profile trough of the die 2. By providing a forging force of 0 parts, it is possible to obtain a more highly accurate tooth profile.

In addition, the punch 3, which has a shape that matches the regular tooth shape, forges the semi-finished product 1 by moving in the radial direction, but in this forming, in particular, the tooth crest 1a is strongly pressed, so this is not commonly done in the past. If you set the punch division position at the top of the tooth,
As shown in FIG. 2, the material flows into the gap N between the punch parts, and the movement of the punch is obstructed. Therefore, by setting the punch dividing position 3a near the gear tooth corner D where the punch 3 is strongly pressed for the first time near the final end of its movement, the above-mentioned problem can be solved.

〔Effect of the invention〕

As explained above, according to the present invention, a semi-finished product formed into a rough tooth shape with extra thickness in the previous process can be
By using the molding die according to the present invention in the post-process of forming into a tooth shape, it is possible to easily produce a timing belt pulley having an R tooth shape, which was conventionally difficult to form with a mold due to large plate elongation. Furthermore, local plate elongation and stress concentration can be suppressed, resulting in excellent strength and precision.

[Brief explanation of drawings]

Fig. 1 is a sectional view of the main parts of the molding die according to the present invention, Fig. 2 is an explanatory diagram showing the conventional punch dividing position, and Fig. 3 is a semi-finished product formed in the previous process. It is a partially sectional view.

Claims (1)

[Claims] A molding tool for timing belt pulleys in which a semi-finished product is formed into a rough tooth shape by adding extra thickness to the outer periphery of the cylindrical drum in the previous process, and then molded into a properly rounded R tooth shape through forging in the post process. In the mold, a die is placed inside the semi-finished product, and a plurality of punches are arranged radially outside the semi-finished product, and both shoulders of the toothed crest and the center of the toothed trough of the die are rounded and convex, A mold for forming a timing belt pulley, in which a dividing position of a punch having a shape that conforms to a regular tooth pattern is determined at a corner R part of a product tooth, and forging is performed by relative movement of the die and punch in a radial direction.