JPH05245566A - Reinforcing method of fitting plate part in pulley - Google Patents

Abstract

PURPOSE:To increase the thickness of the circumferential edge of a fitting hole and prevent the increase in the weight by executing a plurality of specific works to a bottom plate part of a pulley made of sheet metal having a bottom plate part with a fitting hole for a boss and a belt winding part. CONSTITUTION:A boring process to bore a hole part whose diameter is smaller than that of a fitting hole in a bottom plate part 6 of a plate W, a burring process to form a projecting part 8b of truncated conical shape where the diameter at the smallest diameter part is larger than the diameter of a hole part, and a thickness-increasing process to increase the thickness of the part where the projecting part is provided by flattening the projecting part 8b while the diameter of the smallest diameter part of the projecting part 8b formed in the burring process being kept larger than the diameter of the hole part are provided. This arrangement allows the thickness of the circumferential edge part of the fitting hole to be increased, leading to the reinforcement thereof.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mounting plate portion of a sheet metal pulley, and more particularly to a method of reinforcing a mounting plate portion having a mounting hole for a boss fitted to a spindle or a rotary shaft.

[0002]

2. Description of the Related Art Sheet metal pulleys made by subjecting a metal plate material to sheet metal work have been known in the past. FIG. 6 shows a flat belt pulley, FIG. 7 shows a V belt pulley, and FIG. 8 shows a poly V belt. The pulleys are each shown partially in cross section. The cross-sectional shape of each of these pulleys is cup-shaped, a mounting hole 2 is formed in the mounting plate portion 1, the boss 100 is fitted in the mounting hole 2, and the flange portion 101 of the boss 100 is mounted in the mounting hole 2. It is overlapped and joined to the peripheral edge portion 3, and means such as welding is selected for joining. Reference numeral 4 represents a welded portion.

In these sheet metal pulleys, the mounting hole 2
Increasing the dimensional accuracy of the diameter D of the boss 100 helps to improve the mounting accuracy of the boss 100, and increasing the strength of the peripheral edge portion 3 of the mounting hole 2 helps to securely mount the boss 100. .. Therefore, conventionally, the strength of the peripheral portion 3 of the mounting hole 2 is secured by forming the mounting hole 2 in a thick plate material.

[0004]

However, when the method of forming the mounting hole 2 in the thick plate material is adopted, there is a problem in that the hole forming accuracy is restricted by the thickness of the plate material. ..

Further, as can be seen from FIGS. 6 to 8, in each pulley, not so much strength is required in the portions other than the peripheral edge portion 3 of the mounting hole 2, so that such a portion has a peripheral edge portion of the mounting hole 2. It can be formed thinner than the thickness of No. 3.

However, in order to secure the strength of the peripheral portion 3 of the mounting hole 2, when a pulley is manufactured using a plate material having a thickness corresponding to the strength, not only the peripheral portion 3 of the mounting hole 2 but the entire pulley is Since it becomes unnecessarily thick, there is a problem that the material cost is very high and the weight of the obtained sheet metal pulley is significantly increased.

The present invention has been made in view of the above problems, and an object of the present invention is to make the peripheral portion of the mounting hole have a thickness corresponding to the required strength even when a thin plate material is used. It is an object of the present invention to provide a method of reinforcing a mounting plate portion in a sheet metal pulley that can be performed.

[0008]

A method of reinforcing a mounting plate portion in a sheet metal pulley according to the present invention is a sheet metal pulley having a mounting plate portion having a mounting hole for a boss and a belt winding portion. A hole forming step of opening a hole portion having a diameter smaller than that of the mounting hole in a portion corresponding to the plate portion, and the diameter of the smallest diameter portion is equal to the diameter of the hole having a diameter smaller than that of the mounting hole. Burring process to form a frustoconical protrusion that is larger than the diameter of the portion, and the diameter of the smallest portion of the protrusion formed in the burring process is kept longer than the diameter of the hole, To thicken the portion by flattening.

[0009]

In the reinforcing method of the mounting plate portion of the sheet metal pulley as described above, the diameter of the hole formed through the thickening step is defined as the mounting hole of the mounting plate portion of the final sheet metal pulley. If the diameter is set to be the same, the peripheral portion of the mounting hole becomes thicker and is reinforced by the thickening process. Since the peripheral portion of the mounting hole is reinforced by thickening at the time of the thickening step performed after the punching step and the burring step, the punching step and the burring step are performed on the thin plate material. Be seen.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method of reinforcing a mounting plate portion of a sheet metal pulley according to the present invention includes a hole making step, a burring step, and a thickening step, and the present invention shown in FIGS. In the method of reinforcing the mounting plate portion of the sheet metal pulley according to the embodiment, the burring process (FIGS. 2 and 4) and the thickening process (FIGS. 3 and 5) are divided into two stages. In the embodiment of the present invention, not only the upper mold and the lower mold but also the auxiliary mold is used depending on the case. Further, the plate material (hereinafter, referred to as a work) W includes a bottom plate portion 6 corresponding to the mounting plate portion 1 (see FIGS. 6 to 8) and a belt winding portion 5 (see FIGS. 6 to 8). The corresponding peripheral plate part 9 has already been formed by sheet metal working. Hereinafter, a specific description will be given with reference to FIGS.

(1) Drilling step (FIG. 1) This step is a step of forming a hole portion 7a having a smaller diameter than the mounting hole 2 (see FIGS. 6 to 8) in the bottom plate portion 6 of the work W.
The thickness of the bottom plate portion 6 is T1 in FIG. 1, and the diameter of the hole portion 7a is D1.
It is represented by.

In this step, a lower die 51 and an upper die 61 for punching are used. By punching the center of the bottom plate portion 6 of the work W placed on the lower die 51 with the upper die 61, the diameter as described above is obtained. A small hole 7a is opened.

(2) Burring Step (First Burring Step: FIG. 2) In this embodiment, the burring step is divided into a first burring step shown in FIG. 2 and a second burring step shown in FIG. In these steps, the diameter of the smallest diameter portion is smaller than the diameter of the hole portions 7a, 7b over the entire periphery of the hole portions 7a, 7b having a diameter smaller than that of the mounting hole 2 described in FIGS. Is a step of forming the large truncated cone-shaped protrusions 8a and 8b. Here, the first burring process of FIG. 2 will be described.

In the first burring step, a lower mold 52 having a convex portion 52a and a spherical molding surface 52b into which the hole portion 7a opened in the hole forming step can be fitted in a positioned state.
And a vertically movable auxiliary mold 5 arranged around the lower mold 52.
3 and an upper mold 6 having a downwardly expanding tapered molding surface 62a
2 and are used. That is, as shown in the left half of FIG. 2, the hole portion 7a of the work W is fitted and positioned in the convex portion 52a of the lower mold 52, and the bottom plate portion 6 of the work W is supported by the auxiliary mold 53. From this state, the work W is lowered by lowering the upper mold 62 as indicated by the arrow X1 (at this time, the auxiliary mold 53 is machined together with the work W). In this way, each time the work W is hit, the hole edge 7 of the hole 7a is
2 ′ is rubbed while expanding the diameter of the molding surface 52b of the lower mold 52 until it comes into contact with the molding surface 62a of the upper mold 62.
As shown in the right half of the figure, a truncated cone-shaped protrusion 8a is formed. The diameter of the smallest diameter portion of the protruding portion 8a thus formed, that is, the diameter of the inner peripheral surface of the upper end of the protruding portion 8a is larger than the diameter D1 of the hole portion 7a opened in the punching step.

(3) Thickening Step (First Thickening Step: FIG. 3) In this embodiment, the thickening step is shown in FIG. 5 and the first thickening step shown in FIG. It is divided into a second thickening step, and these steps use two protrusions 8a and 8b without changing the diameter of the smallest diameter portion of the protrusions 8a and 8b formed in the burring step. This is a step of thickening the portion by hitting and flattening it. Here, the 1st thickening process of FIG. 3 is demonstrated.

In the first thickening step, the outer peripheral diameter is the same as the diameter of the smallest diameter portion of the protruding portion 8a formed in the first burring step, and the protruding amount is slightly longer than the thickness dimension of the work W. Convex portion 54a and horizontal flat molding surface 54b
An upper mold having a lower mold 54 including a lower mold 54, a vertically movable auxiliary mold 55 arranged around the lower mold 54, a horizontal pressing surface 63a, and a vertical surface 63b for preventing the diameter of the work W from expanding. 63 and are used. That is, as shown in the left half of FIG. 3, by positioning and placing the bottom plate portion 6 of the work W on the auxiliary die 55, the protruding portion 8a is opposed to the molding surface 54b of the lower die 54. From this state, the upper mold 63 is lowered as indicated by arrow X2 to strike the projecting portion 8a of the work W, thereby fitting the projecting portion 8a into the convex portion 54a of the lower mold 54 and at the same time, in the right half of FIG. Flatten the tapped area as shown in. At this time, the work W and the auxiliary mold 55 are the upper mold 6
It is pushed down a little by 3. At this time, the vertical surface 63b of the upper die 63 is fitted to the peripheral plate portion 9 of the work W and is then attached to the work W.
Prevents the diameter from expanding.

In the first thickening step, since the projection 8a is flattened without changing the diameter of the smallest diameter portion of the projection 8a formed in the first burring step, the projection 8a is flattened. The flattened portion (that is, the portion fitted into the convex portion 7b) is thickened by the material flow generated in the process. Therefore, the bottom plate portion 6 of the work W is provided with the hole portion 7b whose peripheral portion is thicker than the thickness of the work W at the time of departure. The diameter of the hole 7b obtained through the first thickening step is indicated by D2, and the thickness of the peripheral edge of the hole 7b is indicated by T2.

(4) Burring Step (Second Burring Step: FIG. 4) In the second burring step, the convex portion 56 can be fitted in the hole 7b formed in the first thickening step in a positioned state.
a and a lower mold 56 having a spherical molding surface 56b, a vertically movable auxiliary mold 57 arranged around the lower mold 56, and an upper mold 64 having a downwardly expanding tapered molding surface 64a. Is used. The procedure is the same as the procedure for the first burring step described in FIG. Therefore, detailed description is omitted. The protruding portion 8 formed in the second burring step
The diameter of the smallest diameter portion of b, that is, the diameter of the inner peripheral surface of the upper end of the protruding portion 8b is larger than the diameter D2 of the hole portion 7b obtained through the first thickening step described in FIG.

(5) Thickening Step (Second Thickening Step: FIG. 5) In the second thickening step, the outer peripheral diameter is the same as the diameter of the smallest diameter small portion of the protruding portion 8b formed in the second burring step. And a projecting portion 58a having a protrusion amount which is slightly longer than the dimension of the thickness T2 of the peripheral portion of the hole portion 7b obtained by the first thickening step and is horizontal and flat. A lower die 58 having a lower die 58b, a vertically movable auxiliary die 59 arranged around the lower die 58, a horizontal pressing surface 65a, and a vertical surface 65b for preventing the workpiece W from expanding in diameter. A mold 65 is used. The procedure is the same as the procedure for the first thickening step described in FIG. Therefore, detailed description is omitted.

Here, the lower mold 5 used in the second thickening step
If the outer diameter of the convex portion 58a of No. 8 is given the same dimension as the diameter of the mounting hole 2 described in FIGS. The hole is the mounting hole 2 itself, and the diameter D3 thereof is larger than the diameter D1 of the hole 7b obtained through the first thickening step. Therefore, D3>D2> D1. Also,
The thickness T3 of the peripheral portion of the mounting hole 2 is thicker than the thickness T2 of the peripheral portion of the hole 7b obtained through the first thickening step. Therefore, T3>T2> T1.

By thus thickening the peripheral portion of the mounting hole 2, even if a thin work W is used at the time of departure, the thickened peripheral portion 3 of the mounting hole 2 is not The strength corresponding to the thickness is given. Further, since the thickness of the work W at the time of departure may be adjusted to the thickness of a portion where thickening is unnecessary, a portion other than the peripheral edge portion 3 of the attachment hole 2 in the sheet metal pulley which is the final product is required. Does not become unnecessarily thick.

For the peripheral plate portion 9, at a stage after thickening the peripheral edge portion 3 of the mounting hole 2 or at a stage before that, depending on the use of the pulley as the final product, Sheet metal processing is performed to give a shape corresponding to a flat belt, a V belt, a poly V belt, or the like.

In the first thickening step of this embodiment,
Although the diameter of the smallest diameter portion of the protruding portion 8a formed in the first burring step is flattened without changing the diameter of the smallest diameter portion, the diameter of the smallest diameter portion of the protruding portion 8a is opened in the punching step. If the method is to flatten the protruding portion 8a while keeping the diameter longer than the diameter D1 of the hole portion 7a,
A method may be adopted in which the diameter of the smallest diameter portion of the protrusion 8a formed in the first burring step is kept smaller and the protrusion 8a is flattened. The same applies to the second thickening step, and the protruding portion 8 formed in the second burring step
If the method of flattening the protruding portion 8b while keeping the diameter of the protruding portion 8a formed in the first burring step longer than the diameter of the protruding portion 8a formed in the first burring step,
A method of keeping the diameter smaller than the diameter of the smallest diameter portion of the protruding portion 8b formed in the second burring step and flattening the protruding portion 8b may be adopted.

Although the burring process and the thickening process are performed in two steps in the above embodiment, the required strength is met by performing the burring process and the thickening process only once. If thickness is obtained, then those steps need only be performed once, while
When the burring step and the thickening step are not performed twice as in the example, the thickness corresponding to the required strength cannot be obtained.
It is possible to obtain a thickness commensurate with the required strength by performing each step in more steps.

Further, in the above embodiment, the bottom plate portion 6
Although the punching step is performed on the work W on which the peripheral plate portion 9 and the peripheral plate portion 9 are formed, the sheet metal working for forming the bottom plate portion 6 and the peripheral plate portion 9 on the flat plate-shaped work is performed after the punching step. It may be done in stages.

[0026]

According to the method of reinforcing the mounting plate portion of the sheet metal pulley according to the present invention, the thin plate member can be perforated in the portion corresponding to the mounting plate portion, so that the perforating step can be easily performed. It can be performed with high precision. Similarly, it is possible to easily and highly accurately form a frustoconical projection on the entire periphery of the hole formed in the punching step for a thin plate material. Further, since the reinforcement of the mounting plate portion is made by thickening only the peripheral portion of the portion corresponding to the mounting hole, it is possible to reduce the material cost waste by thinning the portion that does not require so much strength, Moreover, it is possible to prevent the weight of the sheet metal pulley from increasing.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a punching process in an example of the present invention.

FIG. 2 is an explanatory diagram of a first burring process in the embodiment of the present invention.

FIG. 3 is an explanatory diagram of a first thickening step in the example of the present invention.

FIG. 4 is an explanatory diagram of a second burring step in the example of the present invention.

FIG. 5 is an explanatory diagram of a second thickening step in the example of the present invention.

FIG. 6 is a partial cross-sectional view of a flat belt pulley to which a boss is attached.

FIG. 7 is a partial cross-sectional view of a V-belt pulley to which a boss is attached.

FIG. 8 is a partial cross-sectional view of a poly V belt pulley having a boss attached thereto.

[Explanation of symbols]

 1 Mounting plate part 2 Mounting hole 5 Belt winding part 6 Bottom plate part (a part corresponding to the mounting plate part) 7a, 7b Holes smaller in diameter than the mounting hole 8a, 8b Projection parts 54, 58 Lower mold 63, 65 Top Mold 100 Boss W Work (plate material)

Claims (1)

[Claims] 1. In a sheet metal pulley having a mounting plate portion having a mounting hole for a boss and a belt winding portion, a hole portion having a smaller diameter than the mounting hole is formed in a portion corresponding to the mounting plate portion of the plate material. And a burring step of forming a frustoconical projection in which the diameter of the smallest diameter portion is larger than the diameter of the hole portion over the entire periphery of the hole portion having a smaller diameter than the mounting hole. A step of thickening the portion by flattening the protruding portion while keeping the diameter of the smallest diameter portion of the protruding portion formed in the burring step longer than the diameter of the hole portion,
A method of reinforcing a mounting plate portion of a sheet metal pulley including.