CN1050075C - Method forming of hub from block of plate and belt wheel made from plate - Google Patents

Abstract

The present invention comprises the following procedures: a plate-shaped metal blank 1 is bent into a convex shape; holes 5A are punched at the top of the bent blank 1; under the condition that the extension of the outer peripheral part 1e of the blank 1 toward the outer radial direction is limited, the bent part between the peripheral part 1e and the peripheral part of the holes is bent toward the direction opposite to the bent direction; a tubular wheel hub part 6 protruding toward one side is formed at the central part of the blank 1. Even if the plate is not very thin and inner diameter is small, a wheel hub part with enough wall thickness and protruding height can be formed by using a small pressure machine.

Description

Method for forming hub portion of blank made of sheet material and method for forming pulley made of sheet material

The present invention relates to a method for forming a hub portion of a sheet metal blank, such as a multi-V pulley and a crankshaft pulley, in which a cylindrical hub portion protrudes to one side at the center of a sheet metal blank so as to fit into it The outer side of the rotary body such as the rotary shaft. The present invention also relates to a method for forming a plate-made pulley such as a multi-V pulley using the method.

Conventionally, there have been cold forging, drawing, and burring as methods of forming a cylindrical hub portion protruding to one side in the central portion of a plate-shaped metal material.

However, in the above-mentioned method, in the case of cold forging, the cylindrical hub part is formed by the plastic flow of the material itself, so a blank with a thick plate is used, such as a crankshaft pulley, and it is desirable to have a hub part with a small inner diameter and a relatively large protrusion height. For plate products, it is difficult to form the hub portion with a set protrusion height even if a large press of 2000T to 2500T is used.

In the case of deep drawing, the material will recede along with the deep drawing, and the plate thickness of the obtained product, especially the wall thickness of the hub part, will become too thin, and the strength cannot meet the requirements.

In the case of the inner flange processing method, the hub is first punched with a punching machine, etc., and a hub with a height roughly proportional to the formed hole diameter (equivalent to the inner diameter of the hub) can be obtained, so it cannot be used for a hub with a small inner diameter. Its height is high, and therefore, there is a problem that the range of workability is restricted due to the relationship between the inner diameter and the height.

The present invention is proposed in view of the above-mentioned problems in the prior art, and its purpose is to provide a method for forming a hub portion of a plate blank, which can form the desired hub portion with high precision using a small press without making the plate thickness too thin. The inner diameter, wall thickness and height of the hub part, the object of the present invention is also to provide a method of forming a plate pulley using the above method.

In order to achieve the above object, the first method of forming a hub portion of a sheet material blank according to the present invention is a hub portion of a sheet material blank in which a cylindrical hub portion protruding toward one side of the sheet metal blank is formed at the center portion of the sheet metal blank. form method.

It includes a bending process of bending the above-mentioned metal blank toward the protruding side of the hub portion into a convex shape, a piercing process of piercing the top of the bent blank, and a bending process of forming a cylindrical hub portion. The process is to bend the curved portion between the outer peripheral portion of the blank and the peripheral portion of the hole in a direction opposite to the bending direction in a state where the radially outward extension of the outer peripheral portion of the blank is restricted to form a cylindrical hub portion. .

According to the first method of forming the hub portion of the plate material blank of the present invention, the bending process of the metal blank and the bending process of bending the bent part after piercing are both one type of bending process, so it is possible to prevent the plate from being deformed due to the plastic flow of the material during the drawing process. At the same time, it is possible to use a relatively small press machine even for a relatively thick metal billet, thereby easily forming a predetermined hub portion. Moreover, in the above-mentioned bending process for forming the cylindrical hub portion, since the extension of the outer peripheral edge portion of the blank to the radially outward is restricted, the receding to the outside of the material is prevented, and the material mainly flows toward the hole side of the central portion. Even when the inner diameter is small, it is possible to form a hub portion that ensures a sufficient wall thickness and protrusion height. In addition, since the radially outward extension of the outer peripheral portion of the blank is restricted, the dimensional accuracy of the outer diameter of the product can be improved.

In addition, by providing the inner edge flanging step of protruding the peripheral portion of the hole in the bending direction of the blank between the convex bending step and the bending step of forming the cylindrical hub portion, the hub portion in the following bending step can be accurately formed, Improve yield.

And, after the above-mentioned bending process of forming the cylindrical hub portion, by providing a finishing process, the end face of the cylindrical hub portion formed in the above-mentioned bending process is compressed from the axial direction to a set protrusion height, so that the The protrusion height of the hub portion is set with good processing accuracy, and the excess protrusion in the height direction contributes to the thickening of the hub portion, which is more effective for the strength of the hub portion.

The second method of forming a plate pulley according to the present invention is to form a plate pulley in which a cylindrical hub portion protruding toward one side of the plate metal blank is formed at the center portion of the plate metal blank, and a V-shaped groove is formed on the outer peripheral wall of the blank. form method.

It includes a bending step of bending the above-mentioned metal blank into a convex shape toward the protruding side of the hub portion, a piercing step of piercing the top of the bent blank, and making the radially outward extension of the outer peripheral portion of the blank restricted. The curved portion between the outer peripheral portion of the blank and the peripheral portion of the hole is bent in a direction opposite to the bending direction, and the bending process of forming the flat portion and the cylindrical hub portion is added to the flat portion of the blank after the bending process from the plate thickness direction. A thickening step of pressing to thicken the outer peripheral portion, and a V-shaped groove forming step of forming a V-shaped groove on the thickened outer peripheral wall portion.

According to the second method of forming a pulley made of a sheet material of the present invention, as in the method of forming the hub portion of the first blank made of a sheet material, a relatively small press can be used for the cylindrical hub portion at the center, and it is easy and accurate. The hub portion is formed to secure a sufficient wall thickness and protrusion height. In addition, when the V-shaped groove is formed on the outer peripheral wall after the hub portion is formed, since the flat portion of the blank after the bending process is pressurized from the plate thickness direction, it is possible to reasonably achieve a thinner flat portion for weight reduction of the pulley product in one process. and the thickening of the outer peripheral part necessary for forming the V-shaped groove, so that the manufacturing process of the pulley made of plate can be reduced as much as possible, and the manufacturing cost can be reduced.

The third method of forming a sheet metal pulley of the present invention is a method of forming a sheet metal pulley in which a cylindrical hub portion protruding toward the blank is formed along the central portion of the sheet metal blank, and a V-shaped groove is formed on the outer peripheral wall of the blank. .

It includes a bending step of bending the above-mentioned metal blank into a convex shape toward the protruding side of the hub portion, a piercing step of piercing the top of the bent blank, and making the radially outward extension of the outer peripheral portion of the blank restricted. The curved portion between the outer peripheral portion of the blank and the peripheral portion of the hole is bent in a direction opposite to the bending direction, and the bending process of forming the flat portion and the cylindrical hub portion is added to the flat portion of the blank after the bending process from the plate thickness direction. Pressing and stretching to obtain the required outer diameter of the flat part pressurization process, bending the pressurized flat part outer end side to one side of the pulley rotation axis direction, forming the peripheral wall forming process of the V-shaped groove forming peripheral wall part, and A V-groove forming process in which a V-groove is formed on the peripheral wall.

According to the third method of forming a plate-made pulley of the present invention, it is the same as the above-mentioned method for forming the hub portion of the first plate-made blank. For the cylindrical hub portion at the center, a relatively small press can be used, and it is easy and accurate. The hub portion is formed to secure a sufficient wall thickness and protrusion height. In addition, in forming the V-groove after the hub portion is formed, since the flat portion pressurizing process of pressing and extending the flat portion of the blank after the bending process from the plate thickness direction to obtain the required outer diameter and making the pressed flat portion The peripheral wall forming process in which the outer end is side-bent to one side in the direction of the rotation axis can provide a plate-made pulley with reduced product weight, uniform outer diameter, light weight, and high dimensional accuracy.

The present invention will be further described below by describing the embodiments of the present invention with reference to the accompanying drawings. in:

1A and FIG. 1B are sectional views of main parts illustrating a first bending (deep drawing) step in a method for forming a hub portion of a first sheet material blank according to the present invention;

2A and 2B are sectional views of main parts illustrating the second bending (deep drawing) process;

Fig. 3 is a sectional view of main parts illustrating a piercing process;

4A and FIG. 4B are sectional views illustrating the main parts of the first bending (thinning and drawing) process;

5A and 5B are cross-sectional views illustrating the main parts of the second bending (thinning and drawing) process;

6A and 6B are sectional views of main parts illustrating the third bending (thinning and drawing) process;

7A and 7B are sectional views of main parts illustrating the 4th bending (thinning and drawing) process;

Fig. 8 is a cross-sectional view of the plate blank after the hub portion is formed;

9A and 9B are cross-sectional views of main parts illustrating the bending (deep drawing) process in the second sheet material pulley forming method of the present invention;

Fig. 10 is a sectional view of main parts illustrating the above-mentioned perforating process;

11A and 11B are sectional views of main parts illustrating the same inner edge flanging process;

12A and FIG. 12B are sectional views of main parts illustrating the same bending (thinning and deep drawing) process;

Fig. 13A and Fig. 13B are main part cross-sectional views explaining the hub part finishing process of the same as above;

Fig. 14 is a cross-sectional view of the plate blank after the same hub portion is formed;

Fig. 15 is a half-sectional view illustrating the main part of the same thickening process;

Fig. 16 is a half-sectional view illustrating the main part of the first rotary molding process as above;

Fig. 17 is a half-sectional view illustrating the main part of the second rotary molding process as above;

Fig. 18 is a half-sectional view illustrating the main part of the third rotary molding (multi-V-groove molding) process;

19 is a half-sectional view of main parts illustrating a step of pressing a flat portion in a third method of forming a pulley made of sheet material according to the present invention;

Fig. 20 is a half-sectional view of main parts illustrating the same peripheral wall forming process;

Fig. 21 is a half-sectional view of the main part for explaining the same multi-V-groove forming process.

First, an embodiment of a method of forming a hub portion of a hub-integrated type plate pulley used for a crankshaft pulley among embodiments of the first method of forming a hub portion of a plate material according to the present invention will be described with reference to the drawings. In this example, a circular plate-shaped metal blank with a diameter of about 90 to 100 mm and a plate thickness t of about 5 mm is used, the inner diameter d1 of the hub part is about 12 mm, the outer diameter d2 of the pulley is about 80 mm, and the protrusion height of the hub part is h It is about 35 to 36 mm, and the hub-integrated plate pulley is formed under the above conditions.

As shown in FIG. 1A, in the first bending (drawing) process, a round metal flat blank 1 is placed on a lower die 2 composed of a punch 2a and a punch seat 2b, and then, is pressed by a press. The lower die 2 and the upper die 3 composed of a die 3a and a die base 3b are close to each other, and as shown in FIG. The curved shape at this time is determined by the shape of the tip of the punch 2 a of the lower die 2 and the shape of the inlet tapered surface 3 b 1 of the base 3 b of the upper die 3 .

As shown in Fig. 2A and Fig. 2B, in the second bending (deep drawing) process, replace and use the punch 2a of front end shape different and the die base 3b of entrance taper surface 3b1 shape different, as mentioned above, make upper mold 3 and The lower molds 2 are close to each other, and the blank 1 is drawn into a substantially conical shape.

Then, as shown in FIG. 3 , the above-mentioned curved blank 1 is placed on the special punching seat 4 , and in this state, a hole 5A of about 7 mm is formed on the top thereof using a punching tool 5 of a lathe or a drill.

Next, transfer to the bending (thinning and drawing) process of forming the cylindrical hub portion, as shown in FIGS. On the one hand, the protruding amount of the punch 12a of the lower die 12, the curvature of the front end, and the upper The curvature of the entrance corner portion 13b2 of the mold base 13b of the mold 13, on the one hand, makes the upper mold 13 and the lower mold 12 approach each other, and the bending portion 1b between the outer peripheral edge portion 1e of the above-mentioned blank 1 and the hole peripheral portion 1c is in the bending direction. As a result, the hole peripheral portion 1c is deformed along the outer peripheral surface of the punch 12a to form a cylindrical hub portion 6 at the center. In the several-step bending process, the outer peripheral portion 1e of the blank 1 is in contact with the inner surface of the ring-shaped protrusion 12c formed on the punch holder 12b of the lower die 12, and the radially outward extension is restricted. Therefore, the blank 1 1 cannot retreat radially outward at all, but retreats toward the above-mentioned cylindrical hub portion 6, so that the wall thickness of the cylindrical hub portion 6 is sufficiently thick and the length of the straight portion is sufficiently long.

As shown in Fig. 8, through the above steps, a pulley 7 made of a plate can be obtained with the hub portion 6 integrally formed. The inner diameter d1 of the cylindrical hub portion 6 is as small as about 12 mm, and the protrusion height h is as long as about 35 to 36 mm. The pulley effectively functions as a crankshaft pulley.

Next, a method of forming a multi-V pulley as a first embodiment of the method of forming a second plate pulley of the present invention will be described with reference to the drawings.

As shown in Fig. 9A, in the bending (deep drawing) process, the circular metal flat blank 1 is placed on the lower mold 2 composed of the punch 2a and the punch seat 2b, and then the lower mold 3 is made by a press machine. As shown in FIG. 9B, the upper mold 3 composed of the die 3a and the mold base 3b is close to each other, and the above-mentioned metal blank 1 is drawn toward the protruding side of the hub portion as a whole, and bent into a substantially arc-shaped convex shape. The curved shape at this time is determined by the shape of the front end of the punch 2a of the lower die 2 and the shape of the inlet tapered surface 3b1 of the die base 3b of the upper die 3, which is the same as in the above-mentioned embodiment.

Next, as shown in FIG. 10, the above-mentioned bent blank 1 is placed on the dedicated piercing seat 4. In this state, a hole 5A with a diameter of about 4 to 5 mm is formed on the top of the piercing tool 5 using a lathe or a drill. .

Subsequently, using a metal mold different from that in the above-mentioned bending (deep drawing) process, the outer peripheral edge portion 1e of the blank 1 bent in a substantially circular arc shape and the ring-shaped protrusion 12c of the punch holder 12b of the lower mold 12 are connected. The inner surfaces are in contact, and the extension of the blank radially outward is restricted. This state is shown in FIGS. A peripheral portion 1c of the hole 5A protrudes toward the bending direction of the blank 1 .

Next, it shifts to the bending (thinning and drawing) process for forming the cylindrical hub portion. As shown in Figures 12A and 12B, in this bending (thinning and deep drawing) process, the upper die 13 and the lower die 12 are brought close to each other by using a special punch 12a for thinning and deep drawing, and the outer peripheral portion 1e of the above-mentioned blank 1 and the front The curved portion 1b between the hole peripheral portions 1c of the inner edge flanging process is thinned and drawn in the opposite direction of the bending direction to be bent, and as a result, the above-mentioned curved portion 1b forms a flat portion 8 and a cylindrical hub portion 6. 6 is the above-mentioned hole peripheral portion 1c deformed along the outer peripheral surface of the punch 12a and formed in the central portion. In this bending process, the outer peripheral edge portion 1e of the blank 1 is also in contact with the inner surface of the ring-shaped protrusion 12c of the punch seat 12b of the lower die 12, and the radially outward extension of the blank is restricted, so that the blank 1 It cannot retreat radially outward at all, and can only extend toward the above-mentioned cylindrical hub portion 6, so that the wall thickness of the cylindrical hub portion 6 can be ensured to be sufficiently thick.

After the above-mentioned bending process, as shown in FIGS. 13A and 13B, a hub finishing process is carried out, which is to compress the end face 6a of the cylindrical hub portion 6 from the axial direction by using the finishing punch 12a2 and the die holder 13b2, so that the The cylindrical hub portion 6 protrudes to a predetermined height.

Through the above steps, as shown in FIG. 14 , an intermediate blank 10 of a multi-V-belt pulley made of plate material can be obtained, and a cylindrical hub portion 6 is formed at the center thereof, and a flat portion 8 is formed between the hub portion 6 and the outer peripheral edge portion 1e. , the cylindrical hub portion 6 is integrally formed with the flat portion 8, and the process of using this intermediate blank 10 to form multiple V-shaped grooves in its outer peripheral wall will be described below, and the formation process of multiple V-shaped grooves will be described below.

First, a thickening step of forming the outer peripheral wall portion of the multi-V groove is performed. As shown in FIG. 15 , the lower mold 14 and the upper mold 15 holding the above-mentioned intermediate material 10 are brought close to each other by a press, and the flat portion 8 of the intermediate material 10 is pressed from the plate thickness direction. In this way, the material of the flat portion 8 flows toward the outer peripheral side, thereby increasing the thickness of the outer peripheral portion 10 a of the blank 10 . At this time, the position of the cylindrical hub portion 6 is substantially restricted, its main dimension and wall thickness hardly change, and only a part of the material of the flat portion 8 flows.

Next, the step of cutting and forming the thickened outer peripheral wall portion 10a is performed. The cutting and forming process is shown in Figure 16. The flat part 8 and the hub part 6 of the above-mentioned intermediate blank 10 except the thick-walled outer peripheral wall part 10a are clamped by the rotary inner mold 16 and the rotary upper mold 17, and the inner mold 16 is passed through the rotary inner mold 16. And the rotation of the rotary upper die 17 makes the intermediate blank 10 rotate as a whole. Then, the V-shaped cutting protrusion 18a formed on the outer peripheral surface of the rolling roll 18 is pressed from the outside at the central portion of the thick outer peripheral wall portion 10a of the rotating intermediate billet 10 to cut into the center of the rotating shaft. On the side, the above-mentioned thick outer peripheral wall portion 10a is cut into a V shape.

Subsequently, as shown in FIG. 17 , by the rotation of the above-mentioned rotary inner mold 16 and the rotary upper mold 17, while the intermediate blank 10 is completely rotated, the outer peripheral wall portion 10a of the rotary intermediate blank 10 that is cut into a V shape is formed. The roll roll 19 for forming the wide outer peripheral wall is rotated and squeezed from the outside thereof, and the outer periphery of the intermediate blank 10 is rolled to form the wide outer peripheral wall portion 10b. In addition, the above-mentioned cutting forming step and wide-width peripheral wall forming step may be formed simultaneously by a common die, or may be formed separately by different dies. In addition, the molding is not limited to one time, and may be formed after several times.

Finally, a step of forming multiple V-shaped grooves in the formed wide outer peripheral wall portion 10b is performed. This process is shown in Figure 18, with the rotary inner mold 20 and the rotary upper mold 21 clamping the flat portion 8 and the hub portion 6 of the above-mentioned intermediate blank 10 except for the wide outer peripheral wall portion 10b, and through the rotary inner mold 20 and the rotary The rotation of the upper die 21 causes the intermediate blank 10 to rotate as a whole. Then, from the outer side of the wide outer peripheral wall portion 10b of the rotating intermediate blank 10, the concave-convex shaped portion 22a formed on the outer peripheral surface of the rolling roll 22 is pressed while rotating, and cut into the side of the rotating shaft core. Multiple V-shaped grooves 11 composed of several V-shaped grooves are formed by rolling on the outer peripheral wall portion 10b. And, although this multi-V-shaped groove 11 also can be formed through rolling once, preferably through several times (2～4 times) rolling-pressed forming, the latter comprises multi-V-shaped groove forming preparatory process and finishing process, The finishing process is to further roll the multi-V-shaped grooves of the blank 10 after the multi-V-shaped groove forming preparatory process, and finish the depth and spacing according to requirements.

Next, a method of forming a multi-V pulley as a second embodiment of the third method of forming a pulley made of sheet material according to the present invention will be described with reference to the drawings.

In this second embodiment, as shown in FIG. 14 , a cylindrical hub portion 6 is formed at its central portion, and a flat portion 8 is formed between the hub portion 6 and the outer peripheral edge portion 1e. The cylindrical hub portion 6 and the flat portion 8 is integrally formed, and the process of obtaining the intermediate blank 10 of the multi-V-shaped pulley made of plate material is the same as that of the above-mentioned first embodiment described with reference to FIGS. A process different from the first embodiment, that is, a process of forming multiple V-shaped grooves in the outer peripheral wall portion of the intermediate material 10 will be described.

First, the step of pressing the flat portion of the intermediate material 10 described above is performed. As shown in FIG. 19, the lower mold 23 and the upper mold 24 holding the intermediate material 10 are brought close to each other by a press, and the flat portion 8 of the intermediate material 10 is pressed from the plate thickness direction. Therefore, the material of the flat portion 8 is flowed toward the outer peripheral side, extruded and extended so that the outer diameter D of the billet 10 meets the requirements. At this time, the position of the cylindrical hub portion 6 is substantially restricted, its height and thickness hardly change, and only a part of the material of the flat portion 8 flows.

Subsequently, the peripheral wall forming process is performed, using the lower mold 25 and the upper mold 26 shown in FIG. The outer end portion 8a is bent toward one side in the direction of the pulley rotation axis, specifically, toward a side different from the protruding direction of the cylindrical hub portion 6 to form a multi-V-groove forming peripheral wall portion 10c.

Finally, a step of forming a multi-V-shaped groove in the multi-V-shaped groove-forming peripheral wall portion 10c formed above is performed. This multi-V-shaped groove forming process is substantially the same as that of the first embodiment shown in FIG. 18. As shown in FIG. The flat part 8 and the hub part 6 other than the part 10c rotate the intermediate blank 10 as a whole by the rotation of the rotary inner mold 27 and the rotary upper mold 28 . Then, from the outside of the multi-V-groove forming peripheral wall portion 10c of the rotating intermediate blank 10, the concave-convex molding portion 29a formed on the outer peripheral surface of the rolling roll 29 is pressed and cut into the rotary shaft core side while rotating, Multiple V-shaped grooves 11 composed of several V-shaped grooves are formed by rolling on the peripheral wall portion 10c. In addition, as far as the forming of the multi-V-shaped groove 11 is concerned, although it can be formed by one roll forming as described above, it is certainly preferable to perform rolling forming several times (2 to 4 times), and the latter includes multiple V-shaped grooves. Groove forming preparatory process and finishing process. The finishing process is to further apply rolling to the multi-V-shaped grooves of the blank 10 after the multi-V-shaped groove forming preparatory process, and finish the depth and spacing according to requirements.

Of course, in the embodiment of the first method of forming the hub portion of the plate material blank of the present invention, the same inner edge flanging process as in the first embodiment and the second embodiment of the second plate material pulley forming method of the present invention can also be performed. (refer to FIG. 11 ) and hub finishing process (refer to FIG. 13 ).

In addition, in the first embodiment and the second embodiment of the forming method of the second sheet material pulley of the present invention, although the forming method of the multi-V pulley has been described, it is also applicable to the V-shaped pulley having a single V-shaped groove. The formation of the pulley is also applicable to the formation of a flat pulley whose peripheral wall is wide and flat.

As described above, the hub portion forming method of a sheet material blank according to the present invention is a technique for integrally forming a cylindrical hub portion protruding in one direction at the center portion of a sheet metal blank. The thickness is not too thin, and using a small press, it is possible to form a hub portion that ensures sufficient wall thickness and protrusion height even when the inner diameter is small. In addition, according to such hub portion forming technology, it is possible to provide a method of forming a low-cost plate-made pulley such as a multi-V pulley with as few steps as possible.

Claims (5)

1. the hub portion formation method of a sheet material base material forms towards one of this blank side-prominent tubular hub portion at the central part of plate-shape metal base material; It is characterized in that;

This method comprise make above-mentioned metal base material towards the outstanding side of hub portion bend to convex bending operation, this sweep between the perforation process of curved blank overp0unch and the outer peripheral edges portion that makes above-mentioned blank in blank outer peripheral edges portion under the state that radially extension of foreign side is restricted and the hole peripheral part towards the bending operation of the direction bending opposite, formation tubular hub portion with its bending direction.

2. according to the hub portion formation method of the sheet material base material described in the claim 1, it is characterized in that: setting makes the peripheral part in above-mentioned hole towards the outstanding plunging operation of blank bending direction between the bending operation of above-mentioned convex bending operation and formation tubular hub portion.

3. according to the hub portion formation method of the sheet material base material described in the claim 1, it is characterized in that: behind the bending operation of above-mentioned formation tubular hub portion, finishing step is set, the end face of formed tubular hub portion from the above-mentioned bending operation of axial compression is the projecting height of setting.

4. sheet material system belt pulley formation method along with the central part at plate-shape metal base material forms towards the side-prominent tubular hub portion of this blank one, forms V-shaped groove in the periphery wall portion of above-mentioned blank; It is characterized in that:

Comprise and make above-mentioned metal base material bend to the bending operation of convex towards the outstanding side of hub portion, at this perforation process of curved blank overp0unch, the sweep court direction bending opposite between the outer peripheral edges portion that makes above-mentioned blank in blank outer peripheral edges portion under the state that radially extension of foreign side is restricted and the hole peripheral part with its bending direction, form the bending operation of par and tubular hub portion, from the thickness of slab direction to bending operation after the above-mentioned par pressurization of blank so that the wall thickening operation of outer peripheral portion wall thickening and in the V-shaped groove forming process of the periphery wall portion shaping V-shaped groove of this wall thickening.

5. sheet material system belt pulley formation method along with the central part of plate-shape metal base material forms towards the side-prominent tubular hub portion of this blank one, forms V-shaped groove in above-mentioned blank periphery wall portion; It is characterized in that:

Comprise and make above-mentioned metal base material bend to the bending operation of convex towards the outstanding side of hub portion, at this perforation process of curved blank overp0unch, the sweep court direction bending opposite between the outer peripheral edges portion that makes above-mentioned blank in blank outer peripheral edges portion under the state that radially extension of foreign side is restricted and the hole peripheral part with its bending direction, form the bending operation of par and tubular hub portion, from the thickness of slab direction to bending operation after the above-mentioned par pressurization of blank extend par pressurization operation with the external diameter that need to obtain, outer end, the par lateral bending that this is pressurized is to a side of belt pulley axis of rotation direction, forming V-shaped groove forms with the perisporium formation operation of surrounding wall portion and the V-shaped groove forming process that forms V-shaped groove in surrounding wall portion.

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