JPH0256537B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Application 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.

Prior Art A method for manufacturing sheet metal pulleys for toothed belts has already been disclosed in JP-A-53-77869.
Publication No. 23894 (A), Publication No. 57-177457 (Special Publication No. 1
-42779 Publication) (B) and Publication No. 60-30541 (C), etc., both of which have a shallow bottomed cylindrical body obtained by drawing a metal plate, which corresponds to the inner surface shape of the tooth profile. The punch is attached to a punch having peaks and troughs, and is press-fitted into a die having a concavo-convex shape corresponding to the outer surface shape of the tooth-shaped portion, thereby forming the tooth portion on the peripheral wall of the cylindrical body. 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, since thinning of the bent portion is promoted, the tooth portion cannot be formed accurately in the rounded portion, resulting in a disadvantage that the effective tooth length is shortened.

On the other hand, in the above publications (A) and (C),
Contrary to (B), since the cylindrical body is press-fitted into the die from its periphery, the effective tooth length does not shorten as described above, but on the other hand, burrs protrude from the bottom of the cylindrical body, centering on the tooth bottom. At the same time, the bottom of the cylindrical body near the bottom of the tooth bulges outward, which requires a lot of work to remove the burr, and also causes defects in the end surface of the pulley and uneven pressure on the cylindrical body, resulting in poor roundness of the tooth. There are drawbacks such as going crazy.

Problems to be Solved by the Invention An object of the present invention is to provide a method for manufacturing a toothed pulley made of sheet metal that does not generate burrs or bulges on the bottom of the cylindrical body when forming the tooth profile, and does not shorten the effective tooth length. .

Means for Solving the Problems The present invention provides a cup-shaped body having a circumferential wall portion that becomes the tooth profile of a toothed pulley formed by drawing a metal plate, with peaks and valleys that match the inner shape of the tooth profile. The punch has a trough and a crest that face each other with a gap smaller than the wall thickness of the peripheral wall, and at least the inner diameter of the trough is cut into the toothed part. The bottom of the cup-shaped body is press-fitted into a first die made slightly larger than the finished outer diameter to form teeth and tooth bottoms on the peripheral wall to form a tooth-formed product, and the tooth-formed product is The tooth forming part is opened into a second die having a trough portion having a slightly smaller diameter than the outer diameter of the tooth part by pinching and pressing with a punch that is tightly fitted into the inner surface and a counter punch having a diameter slightly smaller than the tooth part of the tooth part. The gist of the present invention is a method for manufacturing a toothed pulley made of sheet metal, which is characterized in that the toothed pulley is press-fitted from the side and rolled until the toothed portion is brought into close contact with a counter punch.

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 press-fitted into the troughs of the punch by the peaks of the die and the tooth shape is formed. It is formed. Due to the drawing process, the cup-shaped body has a curved bottom inner corner with a relatively large radius and the wall thickness is somewhat thin, but the pressing force into the die accompanied by the compression action is strong. The reduction in wall thickness at the inner corner of the bottom is further promoted. 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 clamped and 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 tooth part of the R, and the cup-shaped body is 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.

Example To manufacture the toothed pulley of the present invention, a cup-shaped body was first formed by drawing a material steel plate suitable for cold casting using a press machine, and a solid lubricant coating treatment effective on the tooth formation shape was applied to the cup-shaped body. Later, 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 can 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 1 as shown in FIG. 1 and a circumferential wall 2 in which tooth-shaped sections are to be formed, and the edges of the circumferential wall 2 are trimmed.

As shown in FIG. 2, the inner diameter di and outer diameter d0 of the peripheral wall portion 2 are such that di is 0.1 smaller than the inner diameter d1 of the pulley tooth portion 4.
It is set to be about 0.2 mm larger, and d0 is about 1 to 2 mm larger than the outer diameter d2 of the 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 forged using a punch 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. It is possible to maintain robust lubricity against various conditions.

The punch 6 has a cylindrical outer peripheral surface with peaks 8 and troughs 9 that match the inner shapes of the teeth 4 and the tooth bottom 5, and the die 7 has an upper cylindrical surface 10 into which the peripheral wall 2 is fitted, Trough portions 11 and peak portions 1 formed below thereof that conform to the outer surface shapes of the tooth portions 4 and tooth bottom portions 5
2, and conical slopes 14 and 14a formed between the cylindrical surface 10 and the mold part 13.
and has. Therefore, the gap length t (Fig. 2) between the peak portion 8 and the valley portion 11 is approximately 0.5 to 1
About mm small. The lower surface of the punch 6 and the upper surface of the counter punch 15 have shapes that match the upper and lower surfaces of the cup-shaped body bottom 1.

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

First, after forming a solid lubricating film on the cup-shaped body 3, this is placed on the counter punch 15, and while the counter punch 15 is supported by the counter pin 16, the punch holder 17 is pushed down to lower the punch 6. As a result, the peripheral wall portion 2 and the bottom portion 1 following this
The outer circumferential portion of the tooth is shortened in diameter by the slope 14 under the friction-reducing effect of the solid lubricant coating, and furthermore, the portion corresponding to the tooth bottom portion 5 is shortened in the center direction by the portion of the slope 14 at the upper end of the crest 12. 4, and is first preformed into the shape shown in FIG. When the punch 6 further descends, the peripheral wall portion 2 is pushed into the gap between the punch 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 1 following this are the peaks 8 and troughs 9 of the punch 6 and the valleys of the mold part 13. Due to the clamping action of the portion 11 and the peak portion 12, a part of the material is deformed while flowing in the direction of the dashed arrow as shown in FIG. 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 process involving the flow of some material as described above is strong, the inner bottom corner a and the outer corner b of the tooth bottom of the tooth forming part 18 are almost right angles as shown in FIG. The end of the portion 4 is rounded.

Next, as shown in FIG. 8, the tooth forming part 18 is fitted into the punch 6 and held between it and the counter punch 19, and the ram 21 is pushed down while pressing the lower surface of the punch 6 with the counter pin 20. Press fit the tooth forming molded product 18 into the second die 22 from its opening side (second
press-fitting process).

The peaks 8 and troughs 9 of the punch 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 23 continues via a slope 25 to a trough 26 whose diameter has been finished to the outer diameter dimension of the tooth 4 of the final product. . In addition, the counter punch 19 has a trough 2 on the 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 step, the material of the tooth portion 4 is
5 and is pressed into the valley part 26, it is rolled toward the bottom part 1, so that the tooth part 4 has the final dimension.
At the same time, the roundness R of the end of the tooth portion 4 is
The missing tooth part is filled in and the tooth preparation molded article 18
A tooth portion 4a having an effective tooth length over the entire height is obtained (FIG. 10).

At the same time, the fillet of the R section in FIG. 10 is increased and the strength is improved.

In the second press-fitting process, the punch 6 and the die 2
In order to match the angular position with the die 22, a block having a crest that fits into the trough 26 of the die 22 is attached to the punch 6.

In the second press-fitting process, a high compressive force acts on the tooth forming part 18, and the material tends to flow within a limited range. 1 In the press-fitting process, the tooth forming part 18 is attached to the mold with the set dimensions.
Pack the ingredients sufficiently densely.

A shaft hole is punched out 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 it is possible to reduce the height of the toothed pulley and make it more compact. There is an effect that the pulley strength can be increased due to the slight decrease in the wall thickness due to straining and the increase in the fillet of the R section in Fig. 10.
Intermediate treatments such as annealing and lubrication can be performed as necessary between the press-fitting process and the second press-fitting process, so this feature is advantageous for the use of thick plates and high-hardness materials, or for processing products with large tooth profiles. There is.

[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. 4 is a partial plan view showing the state of tooth formation during the process, FIG. 5 is a partial plan view for explaining the flow state of the material, and FIG. Figure 7 is a partially enlarged view of Figure 6, and Figure 8
The figure is a longitudinal cross-sectional view showing the second press-fitting process, and Figure 9 is a vertical cross-sectional view showing the second press-fitting process.
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...Tooth part, 5...Tooth bottom part, 6...Punch,
7...First die, 8...Mountain part, 9...Tanibe,
DESCRIPTION OF SYMBOLS 11... Valley part, 12... Peak part, 18... Tooth formation molding, 19... Counter punch, 22... Second die, 26... Valley part.

Claims (1)

[Claims] 1. A cup-shaped body having a circumferential wall that will become the tooth profile of a toothed pulley formed by drawing a metal plate is punched between the peaks and valleys using a punch that has peaks and valleys that match the inner shape of the tooth profile. and a trough portion and a crest portion that face each other with a distance smaller than the wall thickness of the peripheral wall portion, and the inner diameter of the trough portion is made at least slightly larger than the finished outer diameter of the toothed portion. A tooth-forming product is obtained by press-fitting the cup-shaped body from the bottom into the first die to form a tooth portion and a tooth bottom portion on the peripheral wall portion, and the tooth-forming product is combined with a punch and a tooth-forming mold that are tightly fitted into the inner surface of the tooth-forming product. The toothed part is clamped by a counter punch with a diameter slightly smaller than the toothed part of the product, and the toothed part is pressed into a second die having a trough part slightly smaller in diameter than the outer diameter of the toothed part from the opening side of the toothed part, and the toothed part is counter punched. A method for manufacturing a toothed pulley made of sheet metal, characterized by rolling the toothed pulley until it comes into close contact with the sheet metal.