CN85103420A

CN85103420A - Method with manufacturing poly-v pulleys with metal sheet

Info

Publication number: CN85103420A
Application number: CN 85103420
Authority: CN
Inventors: 小田操
Original assignee: Kanemitsu KK
Current assignee: Kanemitsu KK
Priority date: 1985-05-15
Filing date: 1985-05-15
Publication date: 1986-11-12

Abstract

Sheet metal is made the precision machining method of poly-V groove pulley, and this method can keep all even mechanical strength of avoiding of peripheral wall thickness to reduce.Its first step is to begin to take shape a flange on the peripheral wall that becomes the shell base, and thickens above-mentioned peripheral wall.Its second step is when being rotated into the shell base, on the peripheral wall of this thickening, pushes from both sides with a V-shaped groove preliminary working molding roller and the interior pressing mold of rotation, makes and forms many V-shaped grooves that are arranged in order on its wall.This roll has many vertebrate V-shaped grooves.This pressing mold has many V-shaped grooves.In its 3rd step, push peripheral wall with many V-shaped grooves with a fine finishing moulding roll.

Description

Method with manufacturing poly-v pulleys with metal sheet

This invention relates to a kind ofly is processed into the method for poly-V groove pulley with sheet metal, and this belt pulley has many V-shaped grooves, and they are arranged on the peripheral wall of metal slabs according to a fixing pitch.

Because the belt pulley with poly-V groove will make its V-shaped groove be meshed with V-belt, require to form many vertebrate V-shaped grooves, so, the precision of making every effort to each groove is about 0.05mm, thereby requires the pitch through each V-shaped groove of processing, and width and diameter all will reach close tolerance.

In order to manage to satisfy such requirement, the claimant has proposed to make with sheet metal the method for V-shaped groove belt pulley in Japanese patent application No. No54-113820, wherein use V-shaped groove preliminary working molding roller, simultaneously, by effective roll extrusion and such two processes of extruding vertically, becoming to form many V-shaped grooves on the shell base.

Said method is an improvement to previous recommended technology in the US Patent No 3977264.At this is by becoming the shell base along the axial direction backfin, making it form many V-shaped grooves.

In other words, this is a kind of method that forms the V-shaped groove of regulation.The formation of this groove is the wrinkling roll that is positioned at into the shell base outside by means of, by it the one-tenth shell base that the stretched sheet metal base forms is pressurizeed, thereby on peripheral wall, form ripple, simultaneously, also will be by means of one along V-shaped groove preliminary working molding roller movably on the axial direction, push each wrinkling surface under, above-mentioned one-tenth shell base is pushed along axial direction by this roll, and make its rotation, when becoming the rotation of shell base, a fine finishing roll is pressed onto on the V-shaped groove of such moulding.

Therefore, the method that is proposed in this method and the above-mentioned U.S. disclosed patent is compared, this method can make the pitch uniformity of V-shaped groove, because in the process that forms V-shaped groove, on axial direction, peripheral wall is not carried out the backfin that forces, so according to routine, on the peripheral wall that becomes the shell base, irregularly the nip this situation of rolled piece of roll often takes place can be eliminated.In addition,, reduce substandard products or substandard product from this mould, thereby the quality product of making v-shaped pulley with sheet metal is provided because therefore molding or separately be easily can simplify course of working.

Yet, in this method, because when forming V-shaped groove, by extruding force being applied on the peripheral wall of wanting backfin along axial direction, therefore often form irregular fold 9, shown in the V-shaped groove among Figure 17, and this wall thickness is thinner than the other parts in the v-shaped pulley V-shaped groove 3 after processing, its result has reduced the mechanical strength of v-shaped pulley, and this considers to improve further existing problem with regard to causing the application inventor.

For the problem of being referred to above overcoming, the novel method of making v-shaped pulley with sheet metal is provided, make belt pulley exactly when forming V-shaped groove, eliminate the said irregular fold in front as far as possible, guarantee that the thickness between the V-shaped groove equates with the thickness of other parts, to prevent that mechanical strength from reducing, this is a main purpose of the present invention.

The method of making v-shaped pulley with sheet metal is provided, exactly with the peripheral wall of thickening into the shell base in advance, form in the process of V-shaped groove in this base peripheral wall, should prevent the minimizing of peripheral wall thickness and the reduction of mechanical strength as far as possible, this is another object of the present invention.

Provide with sheet metal and make a kind of like this method of v-shaped pulley: being exactly to shorten to process the needed time, and being applicable to and producing by batch, is last purpose of this invention.

In order to achieve the above object, according to first invention of this application, metal slabs are by following processes, so that process the poly-v pulleys made from sheet metal.

In other words, becoming on the shell base peripheral wall to form a curved section (first process that after this is called processing) owing to the deep-draw metal slabs.

So, when rotation and the above-mentioned one-tenth shell of axial compression base, by means of an assistant formation roll, it has the flange that is used to form concave surface, peripheral wall pressurization to above-mentioned bending, and on the peripheral wall that becomes the shell base, begin to take shape flange, meanwhile, become the i.e. thickening (second process that is called preliminary working in the back) simultaneously of thickness increase of shell base.

Secondly, when being supported on one-tenth shell base on the rotation internal mold, utilization is installed in a molding roller with many vertebrate V-shaped grooves on the above-mentioned peripheral wall outside, push with pressing mold in the rotation that is installed in above-mentioned peripheral wall inboard, on the peripheral wall of above-mentioned thickening, form many V-shaped grooves that are arranged in order (forming process that is called V-shaped groove in the back).

At last, along with the rotation that becomes the shell base, utilize a fine finishing moulding roll that is used for machning v grooves just can extrude the V-shaped groove (after this being called the fine finishing process) of such shape.

In second invention of this application, except that the said purpose in front, also have a purpose just to provide and make it form the method for high-precision V-shaped groove as much as possible with sheet metal manufacturing v-shaped pulley.

In order to achieve the above object, second invention provides a kind of processing method, its method is: form a curved section on the peripheral wall that becomes the shell base, meanwhile, by means of an assistant formation roll, first groove that becomes vertebra shape below this roll has the flange that forms concave surface and is fixed on this flange is by pushing the peripheral wall of such bending, on the peripheral wall that becomes parison, begin to take shape a flange and first groove, also increased the thickness of peripheral wall simultaneously.When the interior pressing mold upper support a rotation becomes the inwall of shell base, make its rotation, and make its axial compression, simultaneously, along with the rotation that becomes the shell base, the effect of the preliminary working molding roller by a V-shaped groove with vertebra shape forms many V-shaped grooves that are arranged in order on the peripheral wall of thickening like this.Continuation rotation along with becoming the shell base by an effect with fine finishing moulding roll of many V-shaped grooves, finally extrudes these V-shaped grooves.

The course of working of first invention of Fig. 1 a to Fig. 1 e explanation this application, the local longitudinal sectional view that becomes the shell base of its expression processing and distortion is as first inventive embodiment.

Fig. 2 a to Fig. 2 c is the partial view of critical piece, represents the employed device of first preliminary working process of first invention.

Fig. 3 is the partial sectional view of critical piece, has represented second the preliminary working process of first invention with its device.

Fig. 4 is the partial view of critical piece, represents the forming process of first invention with the V-shaped groove of its device.

Fig. 5 is the partial view of critical piece, represents the fine finishing process and the device thereof of first invention.

Fig. 6 is the zoomed-in view at A place among Fig. 2 a;

Fig. 7 is the zoomed-in view at B place among Fig. 3;

Fig. 8 is the zoomed-in view at C place among Fig. 4;

Fig. 9 is the zoomed-in view at D place among Fig. 5;

Figure 10 a to Figure 10 f is into the partial sectional view of shell base, is another embodiment of first invention of representing by the course of working order;

Figure 11 to Figure 13 represents second process of preliminary working, is that first invents further embodiment;

Figure 11 is a local longitudinal sectional view that becomes the shell base;

Figure 12 and Figure 13 are partial views, represent second process and the device thereof of preliminary working successively;

Figure 14 is in second process of the preliminary working of second invention, the local longitudinal sectional view of the one-tenth shell base of formation;

Figure 15 is a partial view, second process and the device thereof of the preliminary working of second invention of expression;

Figure 16 is the zoomed-in view at E place among Figure 15;

Figure 17 is the local longitudinal sectional view that sheet metal is processed into the belt pulley of a plurality of V-shaped grooves with known method;

Fig. 1 a to Fig. 1 e represents to become in the course of working of first invention the variation of shell base successively.

Fig. 1 a is expressed as the local longitudinal sectional view of shell base 1, Fig. 1 b to Fig. 1 e represents the situation of change of each part-structure of base 1, it is first process according to preliminary working, second process of preliminary working, and the forming process of V-shaped groove and fine finishing process are in sequence.

Fig. 2 a to Fig. 2 c relates to an example of this equipment, is first process that is used as into the preliminary working of shell base 1.

Fig. 2 a particularly, this device of its expression are that the peripheral wall that is used for making into the shell base forms the wrinkle curved section.And Fig. 6 is the zoomed-in view at A place among Fig. 2 a.

In these diagrammatic sketch, pressing mold in support of numeral 401 expressions, 402 and 404 is outer pressing molds, they have and curved section 11a

corresponding grooves

402a, 404a, are used for being specified to the shape of the curved section 11a that forms on the shell base peripheral wall 10.And 403 are top dies, it with outer pressing mold 402 from being compacted into the shell base.

This device that Fig. 2 b represents is that the peripheral wall that is used for making into shell base 1 forms the curved section 11b that concaves, and corresponding with those parts among Fig. 2 a, marks with same numeral number.

In this device, an interior pressing mold 401 has and the corresponding shape in the bottom of curved section 11b, and curved section is recessed inwards in the peripheral wall 10 that becomes shell base 1.

This device that Fig. 2 c relates to is by utilizing the pressure of water, the peripheral wall 10 that makes into shell base 1 forms curved section 11c, in this diagrammatic sketch,

numeral

405 and 406 is a pair of dip molds of going up, and 407 is intermediate support pressing molds, and 408 are pressure pistons, wherein, become the peripheral wall 10 of shell base 1 outwards to protrude, when the water that is full of inner chamber acts on by piston 408, when making the water pressurized, thereby form curved section 11c.

Shown in these diagrammatic sketch, the peripheral wall 10 that first process of preliminary working should make into shell base 1 forms or folding or outwards

curved section

11a, 11b, the 11c of folding inwards, carries out the result of first process of such preliminary working.So become the thickness of the peripheral wall 10 of shell base 1 to be easy to increase, but can not produce difficulty to next process.

As the employed this device of first process of finishing such preliminary working, other many devices except that diagram also can be used for this process, but the structure shown in Fig. 2 a has significant superiority, because peripheral wall 10 is outwards protruded reliably, form desired curved section 11a, the cost of this device also cost than the device among Fig. 2 c is low, and the one-tenth shell base 1 that forms curved section 11a can both make things convenient for and promptly separate from pressing mold.

Fig. 3 and Fig. 7 illustrate the finishing stage and the device thereof of second process of preliminary working.

In these diagrams, the interior pressing mold of a rotation of numeral 601 expressions, it embeds into the inner chamber of shell base 1, so that be supported to the inwall of shell base, and pressing mold 601 is fixed on the lower support pressing mold 602 in this, and in finishing second process of preliminary working, it and the top die 604 with concave part 604a are cooperated, by rotating a rotatable part 603 that links to each other with lower support pressing mold 602, and it had both supported one-tenth parison 1 and had made its rotation.

Numeral 605 relates to an assistant formation roll, and it makes into curved section 11a(or the 11b or the 11c of shell base 1) the peripheral wall flange 13 that tentatively is shaped, simultaneously, also make the peripheral wall thickening.It is more clear that this roll 605 is represented in Fig. 7.It above-mentioned becomes a smooth flat 605b of the curved section of shell base 1 to form by the concave part 605a of preliminarily forming flange 13 with flatly compressing, and this assistant formation roll 605 is one-tenth shell base 1 curved section 11a(or 11b or the 11c that rotating) the front, thereby compress peripheral wall with above-mentioned curved section, meanwhile, along peripheral wall axial with top die 604 from adding a pressure, at this moment, on the peripheral wall that becomes shell base 1, begin to take shape flange 13, make the peripheral wall thickening simultaneously.

Like this, when thickening, just can prevent peripheral wall excessively attenuation in the forming process of continuous V-shaped groove and fine finishing process effectively as the peripheral wall of shell base 1, thus can obtain one in light weight, material province and the high product of intensity.

Fig. 4 and Fig. 8 represent the finishing stage and the device thereof of V-shaped groove forming process.

In these diagrammatic sketch, mark same numerical chracter (as digital substantially) with those corresponding parts among Fig. 3, numbering is not done special explanation here since 700.

The diameter of pressing mold 701 likens to the intracavity diameter of shell base 1 for a short time in rotation, and it has the V-shaped groove of many vertebra shape 705a, and the V-shaped groove of the vertebra shape 701a on the preliminary working molding roller 705 of its groove and a V-shaped groove is corresponding.V-shaped groove preliminary working molding roller 705 cooperates with above-mentioned top die 704, so that form many V-shaped grooves that are arranged in order 2, and keeps certain spacing on the peripheral wall 14 that becomes 1 thickening of shell base.

In this process, top die 704 does not have extruding force to put on this peripheral wall 14, and it often pushes down into shell base 1 with interior pressing mold 701 cooperations of rotation.Therefore, only be that the roll extrusion process works.Because have the pressing mold of many vertebra shape 701a shown in this figure is pressing mold 701 in the rotation, when on the interior pressing mold that V-shaped groove assistant formation roll 705 is pressed onto rotation, just form V shape groove, and during by means of the peripheral wall 14 of the V-shaped groove extruding thickening of the V-shaped groove of vertebra shape 705a and vertebra shape 701a, just can prevent folding line.Therefore, even the place, bottom after the processing of V-shaped groove belt pulley between V-shaped groove 3 can prevent remaining folding line as shown in Figure 17.

Fig. 5 and Fig. 9 represent the finishing stage of fine finishing process, and expression just forms the process and the device thereof of poly-V groove.

In these diagrams, mark with same numerical chracter with those corresponding parts among Fig. 3, numbering is since 800.

The diameter of pressing mold 801 likens to the intracavity diameter of shell base 1 little in the rotation, with used the same in the top V-shaped groove forming process, it is more clear that it is represented in Fig. 9, pressing mold has many vertebra shape 801a, it is corresponding with the vertebra shape 805a on the fine finishing moulding roll 805, pressing mold 801 and the cooperation of fine finishing moulding roll in such rotation, thus roll out V-shaped groove 2 on the peripheral wall of one-tenth shell base 1 furtherly, so that form desired V-shaped groove.

This process also is similar to above-mentioned V-shaped groove forming process, only is by the roll extrusion process this process to be worked.

In this way, on the peripheral wall that becomes shell base 1, form and the dark V-shaped groove 3 of vee-belt engagement, and process the sheet metal poly-V groove pulley shown in Fig. 1 e.

Figure 10 a to Figure 10 f represents with this invention sheet metal to be made the improved example of course of working of poly-V groove pulley.

In these diagrams, mark the peripheral wall of the one-tenth shell base 1 of numeral 15 expression backfins with same numerical chracter with those corresponding parts among Fig. 1.

As these diagrams, according to improved this method, before the V-shaped groove forming process shown in Figure 105, an auxiliary forming process can be provided, exactly in rotation when pressing mold and the roll cooperation that compresses, (this device does not have expression) comes backfin to become the peripheral wall 14 of shell base 1 thickening by the roll extrusion process, so that form and the corresponding groove 15a with appropriate end of the formed V-shaped groove of next process on the peripheral wall 14 that becomes shell base 1.

Like this, before the V-shaped groove forming process, when backfin thickening peripheral wall 14, compare with the process with V-shaped groove that punching press forms, the operating time can shorten.In other words, if make the V-shaped groove 2 shown in Figure 10 d at short notice as far as possible, will between V-shaped groove 2, form each lug boss 2a so, groove 2 is seen Fig. 8 with the bottom 705b(that defeats V-shaped groove preliminary working roll 705 gradually), under abominable situation, the crack may appear in 705b in its bottom, even roll 705 occurs and break.For fear of this class problem, just must advance V-shaped groove preliminary working molding roller 705 step by step, thereby compress thickening peripheral wall 14, and the peripheral wall 14 of thickening is out of shape lentamente, although the operation of course of working is seldom, need the very long operating time.On the contrary, though increase the operation of course of working, the problems referred to above that produce in the backfin process can be avoided fully, and in whole course of working total operating time shorten, like this, the automatic controller by use equipment itself can form poly-V groove at short notice.

In addition, by introducing above-mentioned backfin operation, because in continuously shaped process of poly-V groove and fine finishing process, can make peripheral wall produce reliable plastic deformation, reach needed shape, therefore, according to experience of the prior art, the low stomidium of sheet metal poly-V groove pulley does not expand (the same with shape before the backfin), thereby can obtain a refining sheet metal poly-V groove pulley.

In the above embodiments, peripheral wall 10 (i.e. in the thickening process) its thickness in second process of preliminary working increases equably, but as shown in figure 11, for example by increasing the thickness between the top and bottom, can increase the thickness of wall partly, make the intermediate portion attenuation simultaneously.

The thick structure in this part causes following advantage.

During on request shape moulding peripheral wall, this is just in wrinkling process, in V-shaped groove forming process and the fine finishing process, material deformation concentrates on the intermediate portion of peripheral wall, make intermediate portion be thicker than top and the bottom, but as mentioned above, when increasing thickness partly, even material concentrates on the intermediate portion of peripheral wall, can be so that the peripheral wall thickness of the poly-V groove pulley made from sheet metal be even, be uniform and stable with the mechanical strength of the poly-V groove belt of the sheet metal manufacturing of applying.

Can obtain local so thick structure in the method below.

Shown in Figure 12 and 13, for pushing the peripheral wall of outside protrusion, use has the assistant formation roll 605 ' to replace above-mentioned assistant formation roll 605 of an extruding plane 605b ', push curved section 11a(or the 11b or the 11c of above-mentioned formation simultaneously) peripheral wall located, the top and the bottom of making are thicker than intermediate portion.

So far, be the explanation of the relevant embodiment in first invention.Second inventive embodiments is described below.

In second inventive embodiment, be different from first inventive embodiment, just be the above-mentioned curved section 11a(or 11b or the 11c that form) peripheral wall increased thickness, thereby begin to take shape flange 13, begin to take shape first groove 12 shown in Figure 14 simultaneously, in addition, other forming process is identical, will not state at this, only describe its different part and Figure 15, Figure 16 hereinafter.Numeral 601 " be the interior pressing mold of a rotation; it is the inner chamber that embeds into the shell base; and support its inwall; and on interior pressing mold 601 " is fixed on a lower support pressing mold 602 "; when implementation, be installed in lower support pressing mold 602 " below rotatable object 603 " by rotating one, make its rotation; be fixing simultaneously and support this base, and it has curved section 604 " top die 604 of a " and cooperates to be compacted into shell base 1 with one.

Numeral 605 " is represented an assistant formation roll, is used to into formation flange 13 and first groove 12 on shell base 1 peripheral wall." that represents in Figure 16 is more clear for this roll 605." b forms with the vertebra shape 605 that begins to take shape first groove 12 by the flange 13 that is formed into shell base 1 for it.It with top die 604 " cooperation is along pressing mold 601 in the above-mentioned rotation of extruding on the axle " with and on become shell base 1, increase into the thickness of shell base 1 peripheral wall simultaneously, form curved section 11a(or 11b or 11c at this).When beginning to take shape first groove 12 on the peripheral wall that is becoming shell base 1, in other words, in this process, become shell base 1 to be subjected to top die 604 " axial pressure; and assistant formation roll 605 " propelling compress, with interior pressing mold 601 " the effect spreading of mutually coordinating and two kinds of power that compress the time that rotatablely moves, just base 1 formation is as the shape of Figure 14.

When in the peripheral wall that thickens, beginning to take shape first groove 12, in the poly-V groove forming process afterwards, the topmost vertebra shape limit 705a of the preliminary molding roller 705 of poly-V groove stresses on herein, and insert (see figure 8) in first groove, on these first groove 12 bases, form single downward poly-V groove 2, so just almost completely can limit the precision of 2 fluctuations of poly-V groove, as a result, can make with what sheet metal was done and have a high-precision poly-V groove pulley product.

Promptly in the present embodiment of second invention, it is more rational inserting wrinkling process, before the forming process of poly-V groove, perhaps uses the structure of local thickness, as in first inventive embodiment discussed above.

Can increase wrinkling process, in wrinkling process, simultaneously, by pressurization, and insert first groove with the topmost vertebra shape limit of peripheral wall squeeze roll, the result accurately causes gauffer, and to finish the fine finishing process accurately.

Claims

1, sheet metal is made the method for many V-types groove belt pulley, it is characterized in that:

The first step forms the part of a bending on the garden perisporium that becomes the shell base.

Second step began to take shape a flange on the garden perisporium of above-mentioned one-tenth shell base, push the garden perisporium simultaneously, made the perisporium thickening of above-mentioned garden.When an inwall that becomes the shell base being fixed in the rotation on the pressing mold, be rotated into the shell base, pressurization vertically simultaneously by an assist formation roll with the flange that forms concave surface, has just formed above-mentioned garden perisporium.

The 3rd step formed many V-shaped grooves that are arranged in order, when being rotated into the shell base, in V-shaped groove preliminary working roll and a rotation between the pressing mold by extruding, what make such thickening goes up the formation V-shaped groove garden week.V-shaped groove preliminary working roll has many vertebrate V-shaped grooves, and it is arranged on the outside of garden perisporium, and the rotation internal-pressure die has many vertebrate V-shaped grooves, and it is arranged on the inside of garden perisporium.

The 4th step was the moulding of poly-V groove, when being rotated into the shell base, was pressed onto on the above-mentioned poly-V groove by having V-shaped groove fine finishing roll to one, made its moulding.

2, make the method for poly-V groove pulley according to defined in the claim 1 with sheet metal, wherein, with garden week before of above-mentioned V-shaped groove preliminary working roll at this thickening of extruding, during as the rotation of shell base, by pressurizeing with a V-shaped groove assistant formation roll, make the garden perisporium of thickening tentatively wrinkling, along with the rotation that becomes the shell base, V-shaped groove preliminary working roll presses each wrinkling bottom.

3, according to the method with sheet metal manufacturing poly-V groove pulley of defined in claim 1 or 2, wherein, above-mentioned curved section is to carry out crooked and moulding according to the outwards outstanding a kind of like this mode of the garden perisporium that becomes the shell base.

4, make the method for poly-V groove pulley according to defined in claim 1 or 2 with sheet metal, wherein make a bow shaped surface of outwards protruding for the extruding plane that compresses the above-mentioned assistant formation roll that the garden perisporium uses, formed crooked peripheral wall with above-mentioned assistant formation roll pressed is above-mentioned, the mode that is thicker than intermediate portion with upper and lower end is thickeied into the garden perisporium of shell base.

5, make the method for poly-V groove pulley with sheet metal, it is characterized in that:

The first step forms a curved section in the garden that becomes shell on week.

Second step formed first groove and a flange on the above-mentioned garden perisporium that becomes the shell base, and when the inwall that becomes the shell base being fixed in the rotation on the pressing mold, when being rotated into shell base and axial pressure, by an assistant formation roll, thicken this garden perisporium by pushing above-mentioned formed crooked garden perisporium.The assistant formation roll has one and forms the flange of concave surface and begin to take shape vertebrate first groove.Its groove be arranged on above-mentioned formation concave surface flange below.

The 3rd step formed many V-shaped grooves that are arranged in order on the garden perisporium that thickens like this, by means of the interior pressing mold of a V-shaped groove preliminary working molding roller and a rotation, make on the garden perisporium of such thickening and form V-shaped groove.The preliminary working molding roller has many vertebrate V-shaped grooves, and it is arranged on the outside of garden perisporium.The rotation internal-pressure die has many vertebrate V-shaped grooves, and it is arranged on the inside of garden perisporium.

The moulding of the 4th step poly-V groove.When being rotated into the shell base, be pressed onto on the above-mentioned poly-V groove by the fine finishing roll that has V-shaped groove to, make its moulding.

6, make the method for poly-V groove according to defined in claim 5 with sheet metal, wherein before garden perisporium with above-mentioned V-shaped groove preliminary working molding roller compression and thickening, when being rotated into the shell base, by extruding garden perisporium, make it wrinkling with V-shaped groove assistant formation roll.When being rotated into the shell base, V-shaped groove preliminary working molding roller compresses each wrinkling bottom simultaneously.

7, make the method for poly-V groove pulley according to defined in claim 5 or 6 with sheet metal, the compressive plane that wherein compresses the above-mentioned assistant formation roll that the garden perisporium uses is made a bow shaped surface of outwards protruding, formed crooked garden perisporium with above-mentioned assistant formation roll pressed is above-mentioned, more than, the underpart mode that is thicker than the middle part thickeies into the garden perisporium of shell base.

8, according to the method with sheet metal manufacturing poly-V groove pulley of defined in claim 5 or 6, wherein, above-mentioned curved section is to carry out bending and moulding according to a garden perisporium that becomes the shell base is outwards protruded a kind of like this mode.