JPS6231770A - Toothed pulley made of sheet metal and manufacture thereof - Google Patents

Abstract

PURPOSE:To obtain a toothed pulley having high precision by integrally forming a pulley toothed part and a toothed bottom part onto the peripheral wall part of a cup-shaped body which is integrally formed from a sheet metal and squeeze- working the pulley toothed part towards the bottom part from the opened port side of the cup-shaped body. CONSTITUTION:A tooth-shaped molded article 18 is formed by press-fitting a cup-shaped body 3 into the first die 7 from the bottom part of the cup-shaped body 3 by a punch 6. Then, the tooth-shaped molded article is pressed by the punch 6 and a counter-cunch 19, and press-fitted into the second die 22 from the opened part side of the tooth-shaped molded article 18. Therefore, the toothed part 4 extends to the counter-opened port side through the press-rolling by the inside surface of the bottomed part of the second die 22, and the tooth- deficient part is charged, and a correct tooth shape is formed up to the back surface of the bottom part of the cup-shaped body 3.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a toothed pulley made of sheet metal, such as a pulley for a toothed belt, in which teeth are formed at equal intervals on a peripheral wall, and a method for manufacturing the same.

Conventional technology Methods for manufacturing sheet metal pulleys for toothed belts have already been disclosed in Japanese Patent Publications No. 53-77869 (A) and No. 57-177.
Publication No. 457 (B), Publication No. 60-30541 (C)
In each case, a shallow cylindrical body with a bottom obtained by drawing a metal plate is attached to a punch having peaks and valleys corresponding to the inner surface shape of the tooth profile. Teeth are formed on the peripheral wall of the cylindrical body by press-fitting it into a die that has an uneven shape corresponding to the outer surface shape.

In this case, in the above-mentioned publication (B), since the cylindrical body is press-fitted into the die from the bottom, there is already a bent part with a relatively large radius R at the inner corner of the bottom due to the drawing process in the previous step. Furthermore, thinning of the meat at the bending part is promoted, resulting in a narrower radius.
There is a disadvantage that the tooth portion is not formed accurately in the part, and the effective tooth length is shortened.

On the other hand, in the above-mentioned publications (A) and (C), contrary to publication (B), the cylindrical body is press-fitted into the die from its periphery, so the shortening of the effective tooth length as described above does not occur. However, on the other hand, the burr protrudes from the bottom of the cylindrical body, centering on the tooth bottom, and at the same time, the bottom of the cylindrical body near the tooth bottom bulges outward, which requires a lot of effort to remove the burr, and also causes defects in the end surface of the pulley.
There are drawbacks such as unevenness in the pressure applied to the cylindrical body, which causes the teeth to be out of roundness, and even if they are perfectly round, the outer diameter may vary.

Problems to be Solved by the Invention The object of the present invention is to create a sheet metal in which no bulge occurs at the bottom of the cylindrical body when forming the tooth profile, and the effective tooth length does not shorten! ! To provide a toothed pulley and a method for manufacturing the same.

Means for Solving the Problems The present invention provides a cup-shaped body having a circumferential wall portion which is formed by drawing a metal plate and which becomes the tooth profile portion of a toothed pulley. The punch has a trough and a crest that face the ridge and trough with a gap smaller than the wall thickness of the peripheral wall, and at least the inner diameter of the trough is outside the finish of the tooth profile. The bottom of the cup-shaped body is press-fitted into a first die made slightly larger than the diameter to form teeth and tooth bottoms on the peripheral wall to form a tooth-formed product. The teeth are press-fitted from the opening side of the teeth into a second die having a trough with a diameter slightly smaller than the outer diameter of the tooth by pressing between a punch that fits tightly and a counter punch with a diameter slightly smaller than the teeth of the teeth. and teeth
The object of the present invention is to provide a toothed booby made of sheet metal and a method for manufacturing the same, which are characterized in that the parts are rolled until they come into close contact with a counter bunch.

Function: When the cup-shaped body is press-fitted into the first die from the bottom of the cup-shaped body using a punch, the peripheral wall of the cup-shaped body is compressed into the troughs of the punch by the peaks of the die, and the tooth profile is formed. It is formed. Due to the drawing process, the inner corner of the bottom of the cup-shaped body is curved with a relatively large radius and the wall thickness is somewhat thin. The reduction in wall thickness at the corners is further exacerbated. Therefore, teeth are not formed accurately in the curved portion of the radius, and the effective tooth length is shortened accordingly.

However, the tooth preparation formed in this way is pressed by a punch that is tightly fitted into the inner surface (the punch used for the tooth preparation described above may be used) and a counter punch to open the tooth preparation. When it is press-fitted into the second die from the side, the teeth are rolled by the inner surface of the valley of the second die and extend toward the side opposite to the opening, and this flow of material fills the missing teeth of the R, and the cup-shaped body. The shortening of the effective tooth length is repaired by forming an accurate tooth profile down to the bottom back surface. Since the material flow does not protrude to the back surface of the tooth-formed product due to the counter punch, processing of the back surface after molding is not necessary.

Practical Example To manufacture the toothed pulley of the present invention, first, a material steel plate suitable for cold casting is drawn using a press machine to form a cup-shaped body, and then a solid lubricant coating treatment that is effective for tooth forming is applied to the cup-shaped body. After that, tooth formation processing is performed. As the solid lubricant coating treatment, a zinc phosphate coating coated with lubrication is most suitable, but other methods such as hot-dip galvanizing or electrolytic galvanizing may also be used to obtain the same effect. Further, the solid lubricant coating treatment will be cheaper if it is performed on the raw iron plate or blank.

The blank is first drawn to form a cup-shaped body 3 having a raised bottom portion 1 and a circumferential wall portion 2 in which tooth-shaped portions are to be formed as shown in FIG. 1, and the edges of the circumferential wall portion 2 are trimmed.

As shown in FIG. 2, the inner diameter di and outer diameter do of the peripheral wall portion 2 are
is 0.1 to 0.2 smaller than the inner diameter di of the pulley teeth 4.
mm larger, and do is 1.2 mm larger than the outer diameter d2 of tooth portion 4.
(.

Next, in order to form the pulley tooth portion 4 and tooth bottom portion 5 on the peripheral wall portion 2, the cup-shaped body 3 is cold cast using a bunch 6 and a first die 7 as shown in FIG. In order to reduce friction with the mold during cold casting, the cup-shaped body 3 is treated with a phosphate coating, and then a lubrication treatment is applied to form a metal soap coating on the metal surface. Robust lubricity can be maintained against pressure conditions.

The bunch 6 has a ridge portion 8 and a trough portion 9 on the outer peripheral surface of the cylindrical body, which match the inner shape of the tooth portion 4 and the tooth bottom portion 5, and the die 7 has an upper cylindrical surface 10 into which the peripheral wall portion 2 is fitted, A mold part 13 formed below the mold part 13 and having a valley part 11 and a peak part 12 that match the outer surface shapes of the tooth part 4 and the tooth bottom part 5, and a conical slope formed between the cylindrical surface 10 and the mold part 13. 14 and 14a. Therefore, the gap length t (FIG. 2) between the peak portion 8 and the valley portion 11 is approximately 1 mm smaller than the wall thickness of the peripheral wall portion 2. The lower surface of the bunch 6 and the upper surface of the counter bunch 15 have shapes that match the upper and lower surfaces of the cup-shaped body bottom 1.

Next, the process of forming the boob tooth profile will be described with reference to FIGS. 3 to 8.

First, a solid lubricant film is formed on the cup-shaped body 3, and then placed on the counter bunch 15.
The bunch 6 is lowered by pushing down the bunch holder 17 while supporting it with the counter pin 16. As a result, the peripheral wall portion 2
The diameter of the outer peripheral portion of the bottom portion 1 that follows this is shortened by the slope 14 under the anti-friction effect of the solid lubricant coating, and
Further, a portion corresponding to the tooth bottom portion 5 is pushed toward the center by the slope portion 14 at the upper end of the peak portion 12, and is first preformed into the shape shown in FIG. Bunch 6
As it descends, the peripheral wall portion 2 is pushed into the gap between the bunch 6 and the mold portion 13 due to the compressive action of the slope 14a.

As mentioned above, since the gap length t is smaller than the wall thickness of the peripheral wall 2, the peripheral wall 2 and the outer peripheral part of the bottom l following this are the peaks 8 and troughs 9 of the bunch 6 and the valleys of the mold part 13. Due to the squeezing action of the portion 11 and the peak portion 12, as shown in FIG. 5, a part of the material is deformed while flowing in the direction of the dashed arrow, so that the tooth bottom portion 5 has a desired final dimension and the tooth has an intermediate dimension. A tooth forming molded article 18 (FIG. 6) having a portion 4 is formed (first press-fitting step).

Since the pressing force in the first press-fitting step, which involves the flow of some of the material as described above, is strong, the tooth forming part 18 as shown in FIG.
The inner bottom corner a and the outer corner of the tooth bottom are approximately right angles, but the ends of the teeth 4 are rounded.

Next, as shown in FIG. 8, the tooth forming part 18 is fitted onto the bunch 6 and held between it and the counter bunch 19, and the ram 21 is pushed down while pressing the lower surface of the bunch 6 with the counter pin 20. The tooth forming part 18 is inserted into the second die 22 from its opening side.
Press fit inside (second press fit step).

The peaks 8 and troughs 9 of the bunch 6 are finished to the dimensions of the final product, and as shown in the explanatory developed view of FIG. A trough 23 and a crest 24 into which the tooth bottom 5 fits are formed, and the trough 2
3 continues through a slope 25 to a trough 26 whose diameter has been finished to the outer diameter dimension of the tooth portion 4 of the final product. In addition, the counter bunch 19 has a trough 2 on a cylindrical surface 27 inscribed in the crest 24.
A ridge portion 28 that fits into the inside of the cylindrical portion 6 is formed.

In the second press-fitting process, the material of the tooth 4 is squeezed by the slope 25 and pressed into the valley 26, and rolled toward the bottom 1, so that the tooth 4 is formed into the final dimension of the tooth 4a. At the same time, the missing tooth portion due to the roundness R of the end of the tooth portion 4 is filled in, and a tooth portion 4a having an effective tooth length spanning the entire height of the tooth forming molded product 18 is obtained (FIG. 10).

At the same time, the fillet of the tooth bottom portion 5 increases and the strength is improved.

In the second press-fitting process, in order to align the angular positions of the bunch 6 and the die 22, a block having a peak that fits into the valley 26 of the die 22 is attached to the punch 6.

In the second press-fitting step, a height compressive force acts on the tooth forming molded product 18, and the material tends to flow within a limited range. In one press-fitting process, the material of the tooth forming part 18 is filled in a sufficient distribution into a mold having a set size.

A shaft hole is punched in the bottom part 1 of the product after the second press-fitting step to form a desired toothed pulley.

Effects of the Invention The present invention has the above-mentioned configuration and can form teeth with accurate dimensions over the entire height of the toothed pulley, so the height of the toothed pulley can be reduced and made smaller, and at the same time the toothed pulley can be made smaller. This has the effect of increasing the strength of the pulley due to the slight decrease in wall thickness due to ironing and the increase in the fillet at the bottom of the tooth. Since intermediate treatments such as annealing and lubrication can be carried out during the process, it is advantageous for the use of thick plates and high-hardness materials, or for processing products with large tooth profiles.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a longitudinal cross-sectional view of a cup-shaped body, FIG. 2 is a partially enlarged plan view of a mold for the first press-fitting process, and FIG. 3 is a longitudinal cross-sectional view showing the first press-fitting process. FIG. 4 is a partial plan view showing the state of tooth profile formation in the middle of the process, and FIG.
The figure is also a partial plan view for explaining the flow state of the material, Figure 6 is a vertical cross-sectional view of the tooth preparation molded product, Figure 7 is a partially enlarged view of Figure 6, and Figure 8 is a vertical cross-section showing the second press-fitting process. Figure 9 is the 8th
FIG. 10 is an explanatory developed view of the cross section taken along the line A-A in the figure, and FIG. 10 is a longitudinal cross-sectional view of the product after the second press-fitting step. 1... Bottom part 2... Peripheral wall part 3... Cup-shaped body 4... Teeth part 5... Tooth bottom part 6... Punch
7... First die 8... Peak part 9... Valley part 11... Valley part 12... Peak part 18... Tooth forming molded product 19... Counter punch 22... No. 2 dice 26... Agent Tanibe Patent attorney Yujo - 2 others Figure 3 Figure 4 Figure 5 Figure 6 Figure 8 Figure 9 Figure 10 Procedure amendment October 2, 1985 Day

Claims (2)

[Claims] (1) Pulley teeth and tooth bottom are integrally formed on the peripheral wall of a cup-shaped body integrally formed with a metal plate, and the teeth are ironed over the entire length by ironing the pulley teeth from the opening side of the cup-shaped body toward the bottom. A sheet metal toothed pulley with a uniform cross-sectional shape. (2) A cup-shaped body having a circumferential wall portion that becomes the tooth profile of a toothed pulley formed by drawing a metal plate is punched with a punch having peaks and valleys that match the inner shape of the tooth profile. and a trough that faces the trough with a gap smaller than the wall thickness of the peripheral wall, and the inner diameter of the trough is made at least slightly larger than the finished outer diameter of the toothed part. A tooth forming product is obtained by press-fitting the cup-shaped body from the bottom into the die of No. 1 to form a tooth portion and a tooth bottom portion on the peripheral wall portion, and a punch and a tooth forming product that are tightly fitted into the inner surface of the tooth forming product. A counter punch with a diameter slightly smaller than the tooth part is used to press the tooth part into a second die having a trough part with a slightly smaller diameter than the outer diameter of the tooth part from the opening side of the tooth forming part, and the tooth part is pressed into the counter punch. A method for manufacturing a toothed pulley made of sheet metal, characterized by rolling it until it is in close contact.