JPH0472624B2 - - Google Patents

Description

[Detailed description of the invention]

<<Technical Field of the Invention>> The present invention relates to a pressed product having a tooth profile on its outer periphery, such as a timing pulley or a clutch drum, and a method for molding the same. ≪Prior art and its problems≫ When press-forming a pressed product having a tooth profile on the outer periphery, such as a timing pulley, a clutch drum, or other gear-like products, the connecting part between the cylindrical part and the bottom plate part, that is, the bottom annular part, It is said that it is unavoidable that the material shrinks in the corner portions. In other words, when tooth forming press processing is performed from the bottom annular corner toward the end of the cylindrical part, stress concentration occurs at the corner and the material elongates more than elsewhere. As the wall thickness becomes thinner, breakage may occur, or even if breakage does not occur, the tooth profile will noticeably sag, leading to problems such as a significant reduction in the effective tooth length and a decrease in the rigidity of the pulley. In order to eliminate these problems, conventional materials have been improved and molding methods have been devised. As for improvements in terms of materials, for example,
As shown in Japanese Patent No. 59-78737, there is a blank in which a blank formed in the shape of a circular plate is provided with an annularly raised thick wall portion in advance to compensate for wall shrinkage during processing. However, in reality, it is extremely difficult to build up excess meat at the corners, and it is also troublesome to take out the material. In addition, as an innovation to the molding method,
As shown in Japanese Patent No. 59-23894, there is a blank that has been drawn into a cylindrical shape and is squeezed in the opposite direction to the conventional method to have extra thickness at the annular corner. However, with this molding method, it is difficult for the molded product to come out of the mold, and the mold structure also becomes complicated. Furthermore, there was a drawback in that excess material would conversely bulge at the annular corner, and the burrs would have to be removed. Furthermore, this type of dynamic mechanical part requires more precise processing accuracy than static parts, such as casings and panels. When forming using the press forming method, the product accuracy is determined by the wall thickness of the blank and the precision of the mold, but there are also problems with material flow due to local differences in stress during press forming. Due to uniformity, local unevenness in wall thickness, or nonuniformity due to springback, there are large variations in roundness and cylindricity, and dimensional tolerances are larger than with turned or sintered products. I had to take it. <<Object of the Invention>> The object of the present invention is to prevent the annular corner portion from becoming thinner, and at the same time, further improve the precision of both roundness and cylindricity. In addition, this invention does not require any special ingenuity for the press molding material.
The mold structure of the press mold is also the same as the conventional one, and another purpose is to enable molding by the same method. <<Structure of the Invention>> In order to achieve the above object, the present invention provides a pressed product in which a plate-shaped blank is pressed to form an uneven tooth profile along the pressing direction on the outer periphery, A roughened surface is formed on the inner circumferential surface of the press member, which constitutes a resistance element against the pressing direction, and a protrusion for absorbing excess thickness is formed along the press forming direction. In addition, the manufacturing method is to form a plate blank material into a cup shape, then place the cup-shaped blank material in a die with a tooth shape formed on the inner periphery, and then insert a punch with a tooth shape formed on the outer periphery corresponding to the die shape. When forming tooth-shaped irregularities on the outer periphery of the molded product by fitting onto the inner periphery of the blank material through a die, the tooth-shaped surface of the punch is formed into a rough surface, and grooves for absorbing excess thickness are formed along the pressing direction. It is characterized by the formation of In other words, in the present invention, the rough surface prevents the plate thickness from being elongated due to tensile stress along the pressing direction, and the excess thickness generated by plastic working is absorbed into the groove of the punch, resulting in the corner portion being The objective is to prevent partial thinning of the wall, at the same time make the thickness of the molded product uniform, and improve processing accuracy. <<Description of Embodiments>> Hereinafter, a case in which the present invention is applied to a timing pulley will be described in detail with reference to the drawings. FIGS. 1 to 4 show the process of forming a timing pulley. 1 to 3 show the pre-process, in which a mounting surface 2 is formed in the center of a disc-shaped blank 1 made of a steel plate to form a dish-shaped material, and then a peripheral edge 3 is formed.
is formed into a cup-shaped material by drawing, and in the final step, as shown in FIG. By doing so, a molded product is completed, and further, by smoothing out the burrs generated at the edge of the opening by grinding with a whetstone or the like, the product can be manufactured. FIGS. 5 and 6 show a mold used in the final process of molded products, that is, the tooth profile creation process. The mold in the figure includes a substrate 10, a ring-shaped pressure receiving plate 12 installed on the substrate 10, and a pressure receiving plate 12.
A lower die 14 and an upper die 16 provided at the upper part of the die, a main punch 18 inserted into the center hole formed in the dies 14 and 16, a counter punch 20 located opposite to the lower part of the main punch 18, and the lower part of the main punch 18. It is generally composed of a support plate 22 located at . A punch pin 24 is erected on the support plate 22, passes through the counter punch 20, and faces the punch hole 181 formed in the center of the main punch 18. Furthermore, three cushion pins 28 and 30 are provided inside the mold, with one end facing the cushion pad 26 located at the bottom of the substrate 10. Among the cushion pins, the center pin 30 engages with the bottom of the support plate 22, and the other pins 28 pass through the support plate 22 and engage with the bottom of the counter punch 20. The upper inner side of the lower die 14 is formed into a cylindrical shape, and a desired tooth shape 141 is formed at the lower part thereof. The upper part of this tooth shape 141 is tapered and expanded toward the cylinder. A tooth profile 182 is formed on the outer periphery of the main punch 18 in correspondence with this tooth profile 141 . Furthermore, as shown in FIGS. 7 and 8, a linear bead 182a is formed in multiple stages perpendicular to the press punching direction at the peak of the tooth profile 182, and a press punch is formed in the center of the bead 182a. Grooves 182b for absorbing excess thickness are formed along the pulling direction. The bead 182a is a groove that projects in a reverse tapered shape with respect to the pressing direction shown in the direction of arrow A in FIG. These beads 182a and grooves 182b are formed by electric discharge machining or other machining directions. Next, a molding process using the above mold will be explained. First, the plate-shaped material (second
When a material having the shape shown in the figure) is fed onto the counter punch 20 and the main punch 18 is lowered, the periphery of the material is narrowed into a cup shape by the upper die 16 as shown in FIG. Along the surface, the troughs of the molded product are pushed toward the center and lowered by ironing. On the other hand, when the molded product mountain material descends while being compressed by the punch 18 and die 14, it bites into the bead 182a of the punch 18. Also, when the amount of ironing is large or when the mold clearance is small, bead 18
It is not enough to simply dig into the groove 2a, and the overflowing material flows into the groove 182b as a protrusion. In this case, the inside of the crest of the tooth profile 5 of the product is the 10th
As shown in the figure, the linear bead 5a that follows the shape of the bead 182a is formed in multiple stages, and the groove 182b
A protrusion 5b following the shape of is formed at the center. The ends of the beads 182a bite into the inner surface of the material to prevent excessive flow of the material and prevent overall elongation due to plastic deformation in multiple stages depending on the number of stages of the beads. As an example, the radius of the corner part of the product shown in Figure 10
The material thickness was measured on the surface in 10 degree increments at angles from 0 to 90 degrees, and the results are shown in the table below.

【table】

[Table] In other words, the effect on the tooth profile ridge is the maximum compared to the conventional one that does not have any beads.
The thickness has increased by 12%, and the valleys are the same as before. Moreover, if the excess wall dammed up by the bead 182a becomes excessive, it will cause uneven thickness of the molded product, but the excessive excess wall will get into the groove 182b.
As a result, the protrusions 5b are formed and the excess thickness is absorbed, so that the thickness of each part becomes approximately average. Note that the shape of the bead 5a may be formed in a multi-stage shape as shown in FIG. 11, or may be formed in a knurled shape as shown in FIG. 12. Furthermore, the material may not be a bead but may have a matte finish, as long as it has a shape that provides resistance to prevent the material from flowing along the pressing direction. Further, the tooth profile shape of the main punch 18 may be devised in accordance with these shapes. Further, in the embodiments, the present invention was applied to the inner surface of the crest of the tooth profile of the product, but it may be applied to the trough or both, and in this case, the same processing may be applied to the trough of the tooth profile of the main punch 18. All you have to do is apply it. Additionally, molded products applicable to this invention include:
The present invention can be applied not only to the timing pulley but also to clutch drums or other press-formed products in general that have tooth shapes on the outer periphery. <<Effects of the Invention>> With the configuration described above, the present invention can reduce the shrinkage phenomenon of the bottom annular corner portion. Therefore, in the present invention, there is extremely little sag in the tooth profile, the effective tooth length can be increased, and a decrease in the rigidity of the pulley at the corner portion can be prevented. Further, according to the present invention, the height of the teeth at the crest of the tooth profile can be increased by the reduction in the shrinkage phenomenon, and the performance of pulleys and other similar products can be improved. In addition, during the forming process, the crests are generally elongated, which increases the cutting margin during the grinding process, but in the present invention, the amount of ridges elongated is small, so there is less cutting margin, and the material yield can be improved. . Furthermore, according to the present invention, since excess thickness due to bead biting is absorbed, molding accuracy can be improved in both cylindricity and roundness.

[Brief explanation of the drawing]

Figures 1 to 4 show the molding process of a molded product. Figure 1 is a cross-sectional view of a disc-shaped blank,
The figure is a cross-sectional view showing the state in which it is processed into a dish-shaped plate.
Figure 3 is a cross-sectional view showing the state processed into a cup shape.
Fig. 4 is a perspective view showing the final state of the molded product, Fig. 5 is a sectional view of the mold used in the final process of the molded product,
Fig. 6 is a sectional view showing the machining state using the same mold, Fig. 7 is a partially enlarged perspective view showing the tooth shape of the main punch, Fig. 8 is a sectional view taken along the - line in Fig. 7, and Fig. 9 is the molding Partially enlarged perspective view showing a part of the inner surface of the product, Part 1
Fig. 0 is a sectional view of an annular corner portion of a molded product, Fig. 11 is a partial sectional view showing the inside of a molded product according to another embodiment of the present invention, and Fig. 12 is a molded product according to yet another embodiment of the present invention. It is a figure showing the inside of the product. 5...Tooth profile, 5a...Bead, 5b...Excess thickness absorption protrusion, 14...Lower die, 141...Tooth profile shape, 18...Main punch, 182...Tooth profile shape, 1
82a...bead, 182b...groove for absorbing excess thickness.

Claims (1)

[Scope of Claims] 1. A press workpiece in which a plate-shaped blank is press-worked to form an uneven tooth profile along the press direction on the outer periphery, and the inner peripheral surface of the workpiece is provided with resistance in the press direction. 1. A pressed product having a tooth profile on its outer periphery, characterized in that a rough surface forming an element is formed, and a protrusion for absorbing excess thickness is formed along the pressing direction. 2. The pressed product having a tooth profile on the outer periphery according to claim 1, wherein the rough surface is a multi-stage bead that bites in the pressing direction. 3. The pressed product having a tooth profile on the outer periphery according to claim 2, wherein the bead is formed in a straight line perpendicular to the pressing direction. 4. The pressed product having a tooth profile on its outer periphery as claimed in claim 2, wherein the bead is formed in a curved shape with respect to the pressing direction. 5. The pressed product having a tooth profile on its outer periphery as claimed in claim 2, wherein the bead is formed in a knurled manner intersecting the pressing direction. 6. The pressed product having a tooth profile on the outer periphery according to claim 1, wherein the rough surface is a matte surface. 7 Form a plate-shaped blank material into a cup shape, then place the cup-shaped blank material in a die with a tooth shape formed on the inner periphery, and insert a punch with a tooth shape formed on the outer periphery corresponding to the die into the inside of the blank material through the die. In forming the tooth-shaped unevenness on the outer periphery of the molded product by fitting around the circumference, the tooth-shaped surface of the punch is formed into a rough surface, and grooves for absorbing excess thickness are formed along the pressing direction. A method for forming a press workpiece having a tooth profile on its outer periphery.