JPS60121024A - Manufacture of multistep v-pulley made of sheet metal - Google Patents

Abstract

PURPOSE:To provide high strength to the attaching part of a V-pulley and to make it light in weight as a whole by drawing a sheet-shaped blank material into a closed-end, cylindrical, intermediate formed-part and forming plural V- grooves in its outer peripheral surface after providing thickness reduction to its cylindrical part. CONSTITUTION:A closed-end, cylindrical, primary formed-part 22 is obtained by providing a primary drawing to a discoidal blank material 20, and a secondary formed-part 24 having stepped, closed-end, cylindrical shape is obtained by providing a secondary drawing to the part 22; and then a tertiary formed-part 32 having a bottom part 26 made to be an attaching part, a cylindrical part 28 to be a hub part, and a cylindrical part 30 to be a peripheral wall part, is obtained by providing a tertiary drawing to the part 24. Successively a quartic formed- part 40 is obtained by providing thickness reduction to the part 32 to make the thickness of part 30 less than that of the part 26; and the quintic formed-part 52 is obtained by forming annular projections 48, 50 in the outer periphery of part 40. Thus a multistep V-pulley 2 is obtained by forming plural V-grooves in the cylindrical outer-peripheral surface of part 52.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a multi-stage pulley having a cylindrical shape with a bottom from a predetermined metal plate material, and particularly to a method for manufacturing a multi-stage pulley having a hollow bottom cylindrical shape. The present invention relates to a method of manufacturing a multistage V-pulley made of sheet metal that can be improved.

Today, small annular grooves are formed in multiple stages on the outer circumferential surface of the peripheral wall of an intermediate molded product in the shape of a cylinder with a hollow bottom, obtained by drawing a metal plate material such as a rolled steel plate. A multistage pulley made of sheet metal has been developed. Such a multi-stage V pulley has its bottom part as a mounting part for a predetermined rotating shaft, and also has a multi-stage groove part formed on the outer peripheral surface of a cylindrical peripheral wall part connected to the bottom part, which is a conduction part for transmitting rotational force. It is used by wrapping a belt around it, and has the advantage of being less likely to slip between the transmission belt and pulley, and is relatively lightweight and can be manufactured at low cost. However, it requires a certain level of strength at the bottom where it is attached. There is a need.

Conventionally, in order to manufacture such a multi-stage pulley made of sheet metal, a metal plate-shaped moon is drawn as described above, an intermediate molded product in the shape of a bottomed cylinder is produced using iM, and then the Multi-stage grooves are formed on the cylindrical outer circumferential surface of the intermediate molded product, but considering the processing form of the intermediate molded product, the bottom part that will be the attachment part and the groove molded part (peripheral wall part) will be formed. It has almost the same wall thickness as the cylindrical part.

Therefore, if the thickness of the bottom part is increased to ensure the strength of the mounting part, the thickness of the cylindrical part that becomes the groove forming part will also be correspondingly thicker, which will increase the overall weight, making it difficult to achieve weight reduction. There are also limits. In addition, the thick wall thickness of the cylindrical part that is to become the groove forming part makes it difficult to process the cylindrical part that is to become the groove forming part when giving a predetermined shape to the cylindrical part that is to become the groove forming part in advance. At the same time, it becomes difficult to obtain the desired shape with high precision, which has an adverse effect on the groove forming process, and often causes cracks to form in the groove bottoms of multi-stage grooves, for example.

The present invention has been made based on the above-mentioned circumstances, and its purpose is to provide high strength to the mounting portion of the multi-stage pulley made of sheet metal as described above, while improving the overall strength of the multi-stage pulley. It is an object of the present invention to provide a method for manufacturing a multistage V-pulley made of sheet metal, which can effectively achieve weight reduction and can perform groove forming operations etc. satisfactorily.

In order to achieve such an objective, the present invention includes:
When manufacturing a multi-stage V pulley as described above from a predetermined metal plate material, the plate material is drawn to form an intermediate molded product having a substantially bottomed cylindrical shape, and the intermediate molded product is After thinning the cylindrical part that is to become the peripheral wall part to make it thinner than the bottom part that is to become the mounting part, on the outer peripheral surface of the cylindrical part that has been reduced in thickness,
A molding operation was performed to form the plurality of grooves.

Generally, in a multi-stage pulley that has a cylindrical shape with a bottom, the cylindrical groove molded part (peripheral wall part) is not required to have as much strength as the bottom part, which is the mounting part. Even if it is made relatively thinner than the bottom part, sufficient strength for practical use can be obtained. Therefore, according to the manufacturing method described above,
The bottom part, which is the mounting part, is thick to ensure its strength, while the cylindrical part, which is the groove forming part, is made as thin as possible within the allowable range to reduce the overall weight. be. Also, by making the cylindrical part thinner,
You can give it the desired shape, or add a multi-stage V on its outer circumferential surface.
This also leads to improved workability when performing a forming operation for forming the groove.

By the way, the present invention can be suitably applied to manufacturing a multistage pulley 2 made of sheet metal as shown in FIG. 1, for example. This multi-stage pulley 2 has a stepped bottomed cylindrical shape as a whole, and has a hub portion 4 formed in a relatively small diameter and shallow cylindrical shape with a bottom, and a hub portion 4 that is continuous with the hub portion 4 and has a larger diameter. A cylindrical peripheral wall portion 6 is formed, and a multi-stage groove portion 10 in which a plurality of small grooves 8 are formed in multiple stages on the outer peripheral surface of the peripheral wall portion 6, The mounting portion 12 is to be mounted on the rotating shaft of the motor.

The mounting portion 12 includes a shaft hole 14 into which a rotating shaft is inserted, and a plurality of bolt holes 1 through which bolts for tightening are passed.
6 is formed. The multi-stage V pulley 2 is used with the transmission belt 18 wrapped around the multi-stage Vti section 10 while being fixed to a predetermined rotating shaft at the mounting section 12 thereof.

In the following, the present invention will be explained in more detail by taking as an example the case of manufacturing such a multi-stage V pulley 2.

FIG. 2 shows the manufacturing process diagram.

First, a flat, circular metal plate-shaped material (blank) 20 as shown in (A) is punched out of, for example, a rolled steel plate. Then, by performing a primary drawing process on the blank 20, a primary molded product 22 having a bottomed cylindrical shape as shown in (B) is obtained. Then the -
By further subjecting the next molded product 22 to a secondary drawing process, a second molded product 24 having a stepped bottomed cylindrical shape is obtained as shown in (C). Next, the secondary molded product 24
By further performing a tertiary drawing process (restriking process), the mounting portion 1 is formed as shown in (D).
2, the cylindrical part 28 which should become the hub part 4, the cylindrical part 30 which should become the peripheral wall part 6 in which the multi-stage grooves are formed, and the intermediate part 2. A tertiary molded product 32 as a molded product is obtained.

The wall thickness of the cylindrical portion 30 and the wall thickness of the bottom portion 26 of such a tertiary molded product 32 are equal to the plate thickness t of the blank 20. Strictly speaking, there is some change compared to , but there is virtually no noticeable curvature, and therefore, it can be considered that the thickness is the same as that of the blank 20. In other words, the drawing steps (B) to (D) are performed to obtain such a wall thickness.

Next, the cylindrical portion 30 of the tertiary molded product 32, which is the intermediate molded product, is subjected to a thinning process to make it thinner than the bottom portion 26. That is, the wall thickness of the cylindrical portion 30 is (E)
t as shown in t. Therefore, the difference t. The thickness of the cylindrical portion 30 is reduced by -tl-λ.

This thinning process can be easily performed by ironing the outer peripheral surface of the cylindrical part 30.

For example, it is preferable to use an ironing device as shown in FIG. In the figure, numeral 34 is a die holder, which supports an annular ironing die 36.
A punch 38 is fitted into the ironing die 36. By passing the tertiary molded product 32 attached to the tip of the punch 38 through the die 36, the cylindrical part 30 is squeezed from the outer peripheral surface, and the wall thickness there becomes t. From t! The thickness of the molded product 40 is reduced by ironing to obtain a quaternary molded product 40. During the upward movement of the punch 38, the opening edge of the molded product 40 comes into contact with the stripper 42 which is biased by the spring 44, and the punch 38
It will be separated from.

FIG. 4 is a diagram for explaining such ironing operation more clearly. In this figure, the right half shows the state before ironing, and the left half shows the state after ironing. Before ironing, the cylindrical part 3
0 has a wall thickness t substantially equal to the wall thickness of the blank 20
. , for example, was about 3.21111, but after ironing, it becomes tl, for example, about 2.6 fins, and in this case, a thinning operation equivalent to about Q, Q + n has been performed. The Rukoto. Note that such ironing operation may be repeated not only once but several times a week as necessary, depending on the amount of ironing (to tz = λ) of the cylindrical portion 30. The thickness t□ may be obtained.

On the other hand, regardless of such ironing process, the wall thickness of the bottom part 26, which will become the pulley attachment part, is still maintained at to, so that the thickness obtained after the ironing process is completed, as shown in FIG. 2(E). Wall thickness t of bottom part 26 of quaternary molded product 40
. is kept at, for example, 3.2 mm to ensure sufficient strength there.

However, what about the cylindrical part 30 that should become the groove forming part? D wall thickness t1
As mentioned above, it is made thinner by λ than that, and the thickness is made appropriate for the groove forming process, for example, about 266 fins.

Also, the width dimension β in the center line direction of the cylindrical portion 30
□For example, the cylindrical part 30 of the tertiary molded product becomes slightly longer than the width j2o of the tertiary molded product 32 due to the ironing process, but the cylindrical part 30 of the tertiary molded product is
width dimension β. , and the amount of straining λ. In addition, in FIG. 2(E) and the like, in order to make the difference in thickness (7) clear, the thickness itself and the thickness difference are exaggerated compared to the actual thickness.

By the way, in order to make the cylindrical part 30 a certain amount thinner than the bottom part 26 as described above, the following method can also be adopted. This point will be explained based on FIG.

That is, after forming the tertiary molded product 32 as shown in (D) as described above, the diameter of the cylindrical part 30 is expanded radially outward as shown in (E). The inner diameter of the cylindrical portion 3o is expanded evenly from do to di. Then, the inner diameter dl of the cylindrical portion 30 after the diameter expansion operation is made equal to the inner diameter of the peripheral wall portion 6 of the pulley product. In the figure, the amount of diameter expansion is exaggerated for clarity.

Through such diameter expansion processing, the inner diameter of the cylindrical portion 30 is reduced to dl.
However, as the cylindrical portion 30 is stretched in the circumferential direction, its wall thickness increases from to to t'.
It becomes somewhat thinner up to 2. Thereafter, as shown in (E2), the outer circumferential surface of the cylindrical portion 30 whose diameter has been expanded is subjected to the same ironing process as described above to further reduce the wall thickness t2 of the cylindrical portion 30 to tl. , a quaternary molded product 40 similar to that described above is obtained.

In this way, if the ironing process is performed after the diameter is expanded, the thickness can be reduced in two stages, so to speak, and the burden of the ironing process can be reduced.

Incidentally, in order to reduce the thickness of the cylindrical portion 30, as shown in FIG. 6, it is also possible to employ so-called iron spinning processing. That is, with the molded product 32 rotated around its center line, the squeezing roller 46 is pressed against the outer peripheral surface of the cylindrical portion 30 while rotating, and the squeezing roller 46 is relatively moved in the axial direction in this state. As a result, the wall thickness of the cylindrical portion 30 is reduced from to to t.

In any case, by reducing the wall thickness of the cylindrical portion 30 of the tertiary molded product 32, which is an intermediate molded product, to tl, a quaternary molded product 40 as shown in FIG. 2(E) is obtained. Then, annular protrusions 48 and 50 (groove flanges) are formed at both axial ends of the thinned cylindrical portion 30 of the quaternary molded product 40, respectively, as shown in (F-). The annular protrusions 48, 50 may be formed by rotation molding, for example, by spinning while rotating the quaternary molded product 40, or may be formed by pressing using a press die. In addition, at an appropriate stage before or after this annular protrusion forming process, the bottom 2 which will become the attachment part is
6, the shaft hole 14 and bolt hole 16 are formed.

Next, for the tertiary molded product 52 in which the annular protrusions 48 and 5o are formed and the wall thickness of the cylindrical portion 30 is reduced to tl, the cylindrical portion 30 is removed as shown in (G). A multi-stage V-groove portion 10 consisting of multi-stage V-grooves is formed on the outer circumferential surface of. This groove forming operation can be easily performed by rolling the grooves (not shown) on the outer peripheral surface of the cylindrical part 30 by pressing a roller while the tertiary molded product 52 is rotated around its center line. be able to. Note that such a groove forming operation can be performed according to various known methods, but a detailed explanation will be omitted here.

The left half of FIG. 7 shows the state before groove forming, and the right half shows the state after groove forming. Therefore, the diameter of the cylindrical portion 30 of the target multi-stage V pulley is
For example, if the width is about 120+m and the width is about 25mm, the appropriate wall thickness t1 of the cylindrical part 30 for forming the multi-stage V-groove part 10 is about 2.5 to 2.6mm as described above. In that case, the bottom thickness of the multi-stage groove part 10 (thickness from the inner peripheral surface of the cylindrical part 30 to the groove bottom) is 0.9 to 1.1.
Although it is a crane, the strength of the groove molded part (peripheral wall part) can be obtained sufficiently. In other words, the wall thickness t of the bottom portion 26 that is to become the attachment portion. In this example, the thickness t8 of the cylindrical part 30, which is to become the groove forming part, is approximately 2.6 mm, which is sufficient to maintain the desired strength. Therefore, if it were to be thicker than that, it would be a waste of thickness because it would only increase the weight. Moreover, the wall thickness of the cylindrical portion 30 in which the grooves are to be formed is, for example, 3.
If it is so thick that it exceeds the width of a crane, cracks are likely to form at the bottom of the groove when forming the groove. The reason why cracks are likely to occur at the groove bottom when the cylindrical portion 30 is thick is considered to be as follows.

As shown in FIG. 8, annular protrusions 48 and 50 are formed at both widthwise ends of the cylindrical portion 30 by spinning or press molding, as described above. If the wall thickness of the portion 30 is thick, the annular protrusion 48
When processing, it is difficult to bend, and there is a gap 5 inside.
4 is likely to occur.

Grooving is done by pressing the roller 56 against the outer circumferential surface of the cylindrical part 3o, and pressing the part a when rolling a multi-stage V groove using the plastic fluidity of the metal. However, since there is a gap 54, the metal also migrates to the side of the gap 54. As a result, the height of the peak in section b tends to be less high than other peaks, for example, the peak in section C. In order to raise the peak in section b to the planned height, the grooved roller 56 is Furthermore, it must be pressed against the cylindrical part 30. As a result, the plastic flow conditions become particularly severe in part a, and there
Because something like a fault occurs, it is thought that cracks are likely to occur in part a. If cracks occur at the bottom of the groove, not only will the strength decrease, but the product value will also be lost. is unavoidable.

On the other hand, if the cylindrical part 30 is thinned in advance as in the present invention, it becomes easier to process the annular protrusion 48, etc., and the above-mentioned gap oil 54 is not generated, so that the groove bottom is not formed during groove forming. This effectively prevents the occurrence of cracks.

Furthermore, by making the cylindrical part 3o, which is to become the groove forming part, thinner, the obtained pulley product becomes lighter, while the bottom part 26, which is to become the mounting part, has a relatively thick wall thickness. It has great strength and can withstand usage conditions with high heald tension.

Although the present invention has been described in as much detail as possible in order to facilitate understanding of the present invention, it goes without saying that the present invention should not be construed as being limited by such a specific description.

For example, both drawing of the tertiary molded product 32, which is the intermediate molded product, and thinning of the cylindrical portion 30 of the intermediate molded product can be performed in one process. In other words, when drawing with a press, the gap between the die and punch is adjusted so that ironing can be applied in conjunction with the drawing, or alternatively, the blank 20 is drawn by spinning, and ironing and spinning are performed accordingly. It is also possible to perform a thinning operation on the cylindrical portion 3° at the same time as the intermediate molded product is formed.

Furthermore, the present invention also provides a multi-stage pulley 2 as shown in FIG.
The present invention can be effectively applied not only to manufacturing a multi-stage V pulley having a bottomed cylindrical shape having a simple U-shaped cross section, but also to manufacturing a multistage V pulley having a bottomed cylindrical shape having a simple U-shaped cross section.

In addition, although specific explanations are omitted, it goes without saying that the present invention can be implemented with various modifications and improvements based on the knowledge of those skilled in the art.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an example of a multistage V-pulley made of sheet metal that can be manufactured according to the present invention. FIG. 2 is a process diagram showing an example of a specific processing step of the present invention. FIG. 3 is a cross-sectional view schematically showing a preferred ironing device for performing the thinning process of the present invention, and FIG. 4 is a cross-sectional view showing the ironing process before and after ironing. It is a diagram. Fifth
The figures are process diagrams showing another specific example of the thinning process of the present invention, and FIG. 6 is a sectional view showing still another specific example of the thinning process. FIG. 7 is a cross-sectional view showing a specific example of a molded product before and after the groove forming operation in the present invention, and FIG. 8 explains the reason why cracks occur at the bottom of the V-groove in the conventional pulley manufacturing method. FIG. 2: Multi-stage V pulley 6: Peripheral wall part 10: Multi-stage groove part 12: Retrieval part 20 Ni blank (metal plate-shaped material) 26: Bottom part 30: Cylindrical part 32: Tertiary molded product (intermediate molded product) 36: Ironing Dice 46: Shigoki roller 4s, so:
Annular process applicant: Kojima Press Kogyo Co., Ltd.

Claims (1)

[Scope of Claims] It has a cylindrical shape with a bottom, the bottom of which serves as a receptacle for a predetermined rotating shaft, and a plurality of V-grooves are formed on the outer circumferential surface of the cylindrical peripheral wall connected to the bottom. When manufacturing a multi-stage pulley with a formed part from a predetermined metal plate material, an intermediate molded product having a substantially bottomed cylindrical shape is formed by drawing the plate material, and at the same time, the intermediate molded product is After thinning the cylindrical part to become the peripheral wall part to make it thinner than the bottom part to become the mounting part, the plurality of V-grooves are formed on the outer peripheral surface of the thinned cylindrical part. A method for manufacturing a multi-stage pulley made of sheet metal, characterized in that a forming operation is performed to form it.