JP2011083944A - Molding mold for cylindrical rubber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a molding mold for a cylindrical rubber improved by a further refinement so that venting of air at the axial direction end is smoothly performed without exerting a negative effect on quality or life of a product in the case when the cylindrical rubber having a tapered shape is produced by a bladder molding method. <P>SOLUTION: A mold end part kt forming a diameter contracted surface (s) includes a plurality of flat ring molds (r) having a smaller dimension laminated and arranged in the axial center direction than the dimension in the radial direction in the molding mold for the cylindrical rubber which has the diameter contracted surface (s) and has a tapered cylindrical molded surface M wherein the diameter is contracted to become smaller as the end part in the axial center P direction advances the end in the axial center P direction in order to surround and receive the cylindrical rubber D pressurized and expanded from the inside. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention has a reduced diameter surface that is reduced in diameter so that the diameter decreases as the end of the axial center approaches the end to surround and receive the air spring diaphragm that is pressurized and expanded from the inside. Thus, the present invention relates to a cylindrical rubber molding die having a cylindrical molding surface with a narrowed tip.

  Air springs used in vehicles such as trucks and buses have a so-called rolling diaphragm structure, and for example, those disclosed in Patent Document 1 (FIG. 1) and Patent Document 2 (FIG. 1) are known. ing. As shown in FIG. 3 of Patent Document 1 and FIG. 2 of Patent Document 2, the diaphragm used for this air spring for trucks and buses is considerably larger in the axial direction length than the radial length as shown in FIG. It is generally long and has a tapered cylindrical shape with one end or both ends constricted.

  In order to produce a cylindrical rubber having a narrowed tip as described above, an unvulcanized cylindrical rubber (many rubbers containing reinforcing fibers) placed in a mold are placed inside a bladder (rubber bag). ) Is heated and swelled to press against the molding surface of the mold, thereby forming and vulcanizing the shape. Examples of such a technique include “diaphragm vulcanization mold for air spring” disclosed in Patent Document 3, “rubber heating bladder for vulcanization of tire or air spring” disclosed in Patent Document 4, and the like. Are well known.

  As described above, the diaphragm for the air spring has a tapered cylindrical shape in which both ends in the axial direction are reduced in diameter, and is manufactured by inflating the bladder and pressing and pressing the molding surface of the molding die as the outer frame. In the method (bladder forming method), there is a difficulty in air escape. That is, the unvulcanized cylindrical rubber that is expanded and deformed by the bladder has a shape that is long in the axial direction, first pressed against the molding surface from the central part in the axial direction, and gradually pressed toward both ends in the axial direction. Will come to show. Therefore, the last remaining space between the unvulcanized cylindrical rubber and the molding surface is at both ends in the axial direction on the molding surface. It becomes a product with air mixed in the part, which greatly reduces the quality and life, and is inconvenient.

  Therefore, conventionally, even in the molding of a diaphragm for an air spring for trucks and buses, as in the tire manufacturing method disclosed in Patent Document 5, a plurality or a plurality of small diameter air vent holes called vent holes are molded. In the molding, surplus air is extruded from the vent holes to the outside so that it can be satisfactorily molded into a predetermined shape. However, air spring diaphragms with thinner rubber than tires tend to have a large ratio of vent hole diameter to rubber thickness, making it difficult to control rubber outflow from the vent hole. There is a possibility that a thin part may be generated or an internal cord arrangement as a reinforcing material may be disturbed to shorten the product life.

  Thus, contrivances such as making the hole diameter of the vent hole as small as possible or using means for increasing the internal pressure due to bladder expansion have been made, but the problem has not yet been fully solved. Occasionally, there is a tendency for problems to easily occur for those with a high diameter reduction ratio at both ends, or those with a long axial length compared to the diameter, leaving room for further improvement. It was.

JP 2006-071045 A JP 2006-264204 A JP 2000-052348 A JP-A-9-123175 JP 2009-149206 A

  The object of the present invention is to further improve the escape of air at the end in the axial direction without adversely affecting the quality and life of the product when a tapered cylindrical rubber is produced by a bladder molding method by further contrivance. The object is to provide a mold for cylindrical rubber which is improved to be performed.

In the invention according to claim 1, in order to surround and receive the cylindrical rubber D pressurized and expanded from the inside, the diameter of the end portion in the direction of the axis P decreases toward the end in the direction of the axis P. In a cylindrical rubber molding die having a reduced diameter surface s and a tapered cylindrical molding surface M,
The die end portion kt forming the reduced diameter surface s is constituted by a plurality of flat ring dies r each having a smaller axial dimension than the radial dimension and arranged in a plurality of layers in the axial direction. It is what.

  According to a second aspect of the present invention, in the cylindrical rubber molding die according to the first aspect, the reduction rate per unit axial center P direction length of the diameter of the reduced diameter surface s approaches the end in the axial center P direction. The thickness is set so as to be larger, and the thicknesses in the axial center direction P of the plurality of ring dies r are set to be equal to each other.

  The invention according to claim 3 is characterized in that in the cylindrical rubber molding die according to claim 1 or 2, the cylindrical rubber molding die has an enclosure kg for accommodating and holding the plurality of ring dies r.

  According to a fourth aspect of the present invention, in the cylindrical rubber molding die according to the third aspect, the envelope mold kg is a bowl-shaped one centered on the axis P, and the tapered outer peripheral surface of the ring die r Tapered inner surfaces 17 to 21 fitted to 5d to 9d are formed corresponding to the plurality of ring dies r.

  The invention according to claim 5 is the cylindrical rubber molding die according to claim 3 or 4, wherein the cylindrical rubber molding die is for air discharge extending in a radial direction with respect to the axis P between adjacent ones of the plurality of ring dies r. The auxiliary path bk is formed.

  The invention according to claim 6 is the cylindrical rubber molding die according to claim 5, wherein the air discharge passage extends along the axis P direction between the plurality of ring dies r and the envelope die kg. It is characterized in that bt is formed in a state following the auxiliary route bk.

  According to the invention of claim 1, the details will be described in the section of the embodiment, but a plurality of flat ring molds are arranged in the axial direction, and a plurality of ring molds are completely formed from a microscopic viewpoint. Since it cannot be joined in a sealed state and there is a gap, a gap between adjacent ones of a plurality of ring molds, or a gap between a ring mold and another mold, is not possible. The air escapes through and good mold forming can be performed without problems such as air mixing into the cylindrical rubber and shape defects. As a result, when creating tapered cylindrical rubber by the bladder molding method, further improvements are made so that air can be satisfactorily vented at the axial end without adversely affecting product quality and life. Thus, an improved mold for cylindrical rubber can be provided.

  According to the invention of claim 2, although described in detail in the section of the embodiment, air discharge in accordance with the required air discharge amount, that is, excessive rubber flow due to excessive air discharge area, It is possible to discharge air well without passing through it, and it is possible to better mold the cylindrical rubber with a desired shape and size at the end where the diameter of the cylindrical rubber is reduced.

  According to the invention of claim 3, since the enclosure type that accommodates and holds the plurality of ring molds is equipped, the plurality of ring molds can be assembled after being arranged in a concentrated manner compared to the case where there is no ring mold. Excellent workability and stable assembly.

  According to the invention of claim 4, since each ring mold is fitted and accommodated in the envelope mold by taper fitting, a plurality of ring molds are integrated more accurately, and a smooth molded surface free from steps or misalignment is obtained. Can contribute to formation.

  According to the invention of claim 5, in addition to the air discharge from the gap between the ring dies, the air discharge can also be performed from the auxiliary path extending in the radial direction. Can be provided. Further, as in claim 6, if the air discharge path extending along the axial direction is formed between the plurality of ring molds and the envelope mold, the air discharge performance is further improved. It will be a thing.

Whole sectional view showing a mold for cylindrical rubber (Example 1) Exploded view showing the configuration of the end of the reduced diameter side of the mold Sectional view of the upper part of the mold showing the intermediate state of the expansion stroke Sectional view of the main part showing the air escape path at the top of the mold (A) is a plan view of the ring type, (b) is a bottom view of the ring type. Ring-shaped main part cross-sectional view showing groove line and vent line (A) is sectional drawing of the principal part which shows the cross-sectional shape of a groove line, (b) is sectional drawing of the principal part which shows the sectional shape of a vent line.

  Hereinafter, an embodiment of a cylindrical rubber molding die according to the present invention will be described with reference to the drawings, mainly for use in an air spring diaphragm whose one end is clearly reduced in diameter.

[Example 1]
FIG. 1 is a cross-sectional view of a cylindrical rubber mold A (hereinafter simply referred to as “mold A”) for molding an air spring diaphragm suitably used for trucks and buses. This forming mold A includes an upper mold 1 (mold end kt), a middle mold 2, a split mold 3, a lower mold 4, and five ring molds 5 to 9 accommodated in an upper part, and has a substantially cylindrical shape. It is made up of things. An upper spacer 10 is provided on the upper upper side, and 11 is an opening / closing device that opens and closes a split mold 3 composed of three arcuate molds 3A using a fluid pressure cylinder 12 and a link mechanism 13.

  The mold A includes an inner surface 1 a of the upper mold 1, inner peripheral surfaces 5 a to 9 a of the ring molds 5 to 9, an inner surface 2 a of the middle mold 2, an inner surface 3 a and a lower ceiling surface 3 b of the split mold 3, and a top of the lower mold 4. It has a molding surface M composed of the peripheral surface 4a. In other words, in order to surround and receive the cylindrical rubber D that is pressurized and expanded from the inside, it has a reduced diameter surface s that is reduced in diameter so that the upper end in the direction of the axis P approaches the upper end. And has a cylindrically shaped molding surface M. The cylindrical rubber D becomes a diaphragm for an air spring as a product by molding with the mold A.

  As shown in FIGS. 1 and 2, the upper mold 1 includes a plurality of ring molds r and an enclosure mold kg that accommodates and holds them. The enclosure type kg has first to fifth tapered inner surfaces 17 to 15 formed corresponding to the outer peripheral surfaces 5d to 9d so as to fit and accommodate first to fifth ring dies 5 to 9 described later. 21. The enveloped kg is formed with an annular passage 22 through which heating steam is passed, and is equipped with a steam supply pipe 23 and a discharge pipe 24.

  As shown in FIGS. 1 to 4, the plurality of ring dies r are composed of five pieces of first to fifth ring dies 5 to 9 in order from the largest at the lowest side. Only the first ring 5 is bolted and fixed to the surrounding mold kg, and the second to fifth ring molds 6 to 9 are sandwiched and fixed between the first ring mold 5 and the surrounding mold kg. Each of the ring dies 5 to 9 has a groove line g formed on the inner peripheral surfaces 5a to 9a and a vent line b formed on the upper surfaces 5c to 9c and the outer peripheral surfaces 5d to 9d. The groove line g is a continuous groove formed on the molding surface M in order to form a ridge integrally formed on the outer peripheral surface of the diaphragm D for reinforcement and appearance improvement. The vent line b is a radial groove (an example of an auxiliary path) bk formed on the upper surfaces 5c to 9c as an air path that assists air escape during molding, and a vertical direction that is recessed into the outer peripheral surfaces 5d to 9d. It is a general term for a groove (an example of an air discharge path) bt.

  The groove line g and the vent line b will be described using the second ring type 6. As shown in FIGS. 4 and 5, the second ring mold 6 includes a curved inner peripheral surface 6a that is a molding surface M, a flat bottom surface 6b, a flat upper surface 6c, and an outer peripheral surface that is an inclined outer peripheral surface (tapered outer periphery). An example of the surface) 6d and a cut surface 6e which is a vertical outer peripheral surface continuing below the outer peripheral surface 6d. As shown in FIG. 4 (a), the groove line g is a lateral groove formed across the upper surface 6c and the outer peripheral surface 6d at 20 locations at equal angles (18 degrees) with respect to the axis P. The vent line b is a groove formed in the inner peripheral surface 6a at 20 locations for each equal angle (18 degrees) around the axis P. In the first and third to fifth ring molds 5 and 7 to 9, the inner peripheral surface, the bottom surface, the upper surface, the outer peripheral surface, and the cut surface are denoted by the corresponding reference numerals and explained.

  The groove line g has a depth gh and a width gw of the same dimension (hg = hw) as shown in the cross-sectional view of FIG. 7A, and the corners and groove side surfaces of the groove bottom surface 14 and both groove side surfaces 15 and 15. 15 and the inner peripheral surface 6a are rounded at the corners, and the depth gh and the width gw are both 0.5 mm as a dimension example. As shown in the cross-sectional view of FIG. 7B, the vent line b is a triangular groove having left and right inclined side surfaces 16 and 16 and having a width w larger than the depth h. Is 0.25 mm and the width w is 0.5 mm. These groove lines g and vent lines b (bk, bt) are formed so as to be continuous in the radial direction, and are similarly set in the first and third to fifth ring dies 5, 7-9. Yes.

  As shown in FIG. 4, a groove line g corresponding to the groove line g of each of the ring dies 5 to 9 is formed on the upper bent surface 1 k of the surrounding mold kg which is the molding surface M as the upper mold 1. Yes. As shown in FIGS. 2, 3 and 5 (a), positioning pins 5 p to 9 p are driven into one place on the upper surfaces 5 c to 9 c of the ring dies 5 to 9. Accordingly, by incorporating the ring dies 5 to 9 into the surrounding die kg in a state where the positioning pins 5p to 9p are fitted in the corresponding insertion holes 1h formed in the upper die 1, as shown in FIG. Thus, the envelope type kg, the groove lines g of the ring molds 5 to 9 and the vent lines b of the ring molds 5 to 9 are set so as to be continuous.

  The above-mentioned groove line g is a vertical groove line extending in the same direction as the axis P or in the radial direction, whereas a circumferential horizontal groove line gy formed across the ring shapes adjacent to each other in the vertical direction is shown in FIG. . That is, in the case of the second ring mold 6, the horizontal groove line gy may straddle with the lower first ring mold 5 and straddle with the upper third ring mold 7. The upper horizontal groove gy is composed of a lower groove groove 6 f formed at the upper end portion of the second ring mold 6 and an upper groove groove 7 g formed at the lower end portion of the third ring mold 7. The lower horizontal groove gy is constituted by a lower groove groove 5f formed at the upper end portion of the first ring mold 5 and an upper groove groove 6g formed at the lower end portion of the second ring mold 6.

  As shown in FIG. 4, in the state where the first to fifth ring molds 5 to 9 are assembled to the upper mold 1, the groove lines g, the vent lines b, and the lateral groove lines gy of the ring molds 5 to 9 are all present. It is connected and continuous. Accordingly, during molding with the bladder B inflated, the air between the cylindrical rubber D and the reduced diameter surface s passes through the gap between adjacent ones of the first to fifth ring molds 5 to 9. In addition to being discharged to the outside, even after passing through each groove line g and each side groove line gy, it will be discharged to the outside, and it will be possible to mold well without the inconvenience of air remaining and entering the cylindrical rubber. ing.

  And in the upper mold | type 1 which is the mold | die edge part kt which forms the diameter-reduction surface s, five flat ring type | molds r whose axial center P direction dimension is small compared with radial direction dimension are 5 pieces (a plurality of several An example) It is configured by stacking, that is, the first to fifth ring molds 5 to 9. The five ring dies 5-9 forming the tapered diameter-reduced surface s have the same thickness (length in the direction of the axis P) t5 to t9 (not shown in the drawing). From t5 = t6 = t7 = t8 = t9), the circumferential surface length (not shown) of the inner circumferential surfaces 5a to 9a curved in the vertical direction along the axial center P direction becomes longer as the upper ring type, And the way of increasing becomes larger as the upper ring type.

  That is, the reduction rate per unit axis P direction length of the diameter on the reduced diameter surface s is set so as to increase toward the end in the axis P direction, and the first to fifth ring molds 5 to 5 are set. The thicknesses t5 to t9 of 9 are set to be equal to each other. Thereby, the inner peripheral surface actual width which is the length along the axis P direction of the inner peripheral surfaces 5a to 9a (that is, the interval between the adjacent horizontal grooves gy in the axis P direction) is the end in the axis P direction. It gets wider as you go (up). If this interval is called a “ring-type pitch”, it can be said that it becomes wider toward the end in the direction of the axis P. Further, if the thicknesses t5 to t9 of the ring dies 5 to 9 are referred to as “ring type pitches”, it can be said that they have equal pitches.

  Since the inner peripheral surface actual width of the first to fifth ring molds 5 to 9 is longer toward the end in the direction of the axis P, many ring molds are used when the amount of air accumulated in the reduced diameter surface s during molding is large. The air can be quickly discharged from the gap between the r and the vent line b, that is, with a large air discharge area. And as the pressure molding progresses and the amount of air contained decreases, the reduction rate of the air discharge area increases, and the air discharge in accordance with the actual situation, that is, excessive flow of rubber due to too much air discharge area, Therefore, it is possible to cause a good air discharge without a problem of omission due to being too small. Accordingly, it is possible to better mold the cylindrical rubber D with a desired shape and size at the end where the diameter of the cylindrical rubber D is reduced.

  In the mold A, when the cylindrical rubber whose end (or both ends) in the axial direction is reduced in diameter is used as a diaphragm (product), the reduced end of the mold A is a continuous ring. It consists of molds 5-9. Each of the plurality of ring dies 5 to 9 is inscribed in the upper die 1 and circumscribed on the outer surface of the cylindrical rubber D when the molding is completed. The cylindrical rubber D, ie, the diaphragm, which has been pressurized and expanded by the bladder (rubber bag) B, gradually discharges the inward air from the ring molds 5 to 9, so that the wall stress due to the pressure expansion is applied to the bladder. Air can sufficiently escape even at the diameter-reduced end portion that is lower than the central portion in the axial direction. In that case, if the ring-shaped thickness is set to be smaller in the portion having a smaller diameter (inner diameter), the air discharge effect may be enhanced.

  As shown in FIGS. 1 and 2, the middle die 2 is a substantially straight cylindrical shape, and is formed with a ring passage 25 that is a passage for steam, and a steam supply pipe 26 and a discharge pipe 27. Equipped. The inner surface 2a which is the molding surface M of the middle mold 2 is also provided with a display mold portion 28 for molding longitudinal and horizontal groove lines g, gy and specifications such as a product number and a model on the diaphragm surface.

  The split mold 3 composed of three arc molds 3A has an inner surface 3a which is a molding surface with a slightly reduced diameter on the lower side, an arc path 29 as a steam path, supply and discharge pipes 30 and 31, and vertical and horizontal grooves. Lines g and gy are provided for each arc shape 3A. The lower ceiling surface 3b is also formed for each arc shape 3A. Although not shown in the drawings, the part of the lower part of the split mold 3 whose diameter is to be reduced is similar to the upper mold 1 in the same manner as the upper mold 1. It is good also as a structure which consists of a type | mold, ie, a structure excellent in air discharge | emission.

  As shown in FIGS. 1 and 2, the lower mold 4 is mounted and fixed on the pedestal 32, and the lower bead portion as a diaphragm is formed by cooperation with the divided mold 3 that is driven and opened by the opening / closing device 11. Has the role of pinching and fixing. As described above, the lower mold 4 is formed with the top peripheral surface 4a that is an annular concave surface that is the molding surface M and that forms a pair with the lower ceiling surface 3b. 33 is an annular path which is a steam passage, and 34 is a supply / discharge pipe.

  Here, the main part of processing by the bladder forming method will be described. FIG. 3 shows the middle part of the bladder in the set state in which the upper part of the unvulcanized cylindrical rubber D is locked and fixed to the mold A via the upper mounting jig J and the upper part of the bladder B is locked and fixed. Show. That is, the bladder B is inflated and pressed against the molding surface M from the central portion of the cylindrical rubber D in the axial center P direction, and the reduced diameter upper end (end) of the cylindrical rubber D is still on the molding surface. M is not yet reached, and it can be seen that there is a space between the cylindrical rubber D and the mold A. As the bladder B continues to expand, the space is gradually gathered and reduced at the upper end, and finally, the entire outer surface of the cylindrical rubber D is pressed against the molding surface M to finish the molding. Upon completion of the mold forming, the cylindrical rubber D is formed into a diaphragm having a predetermined shape and vulcanized.

  The space between the cylindrical rubber D and the molding surface M is pressed and contracted by the cylindrical rubber D which expands due to the expansion of the bladder B, and the air present there escapes from the upper mold 1 portion to the outside of the mold. That is, when viewed microscopically, the ring molds 5 to 9 cannot be joined together in a completely sealed state, and there are gaps. Therefore, air escapes through the gap between adjacent ones of the first to fifth ring molds 5 to 9 and the gap between the fifth ring mold 9 and the upper mold 1 to the cylindrical rubber. Good mold forming can be performed without problems such as air mixing and shape defects, and this is the effect of dividing the mold of the reduced diameter surface s into a plurality of flat ring molds 5 to 9 that are thin vertically.

  In the first embodiment, since the groove line g and the vent line b are formed in each of the ring molds 5 to 9, etc., air is discharged from the vent line b in addition to the gap between the ring molds. Therefore, it is devised so that air can be discharged even better. Since each vent line b is formed to be continuous with each other, efficient air discharge is possible. And since the groove line g which also serves as a surface reinforcing projection as a product (diaphragm) is formed in alignment with the vent line b, the groove line g is formed when the cylindrical rubber D is pressed against the molding surface M. It can also be expected to serve as an air discharge guide.

  When forming a thin diaphragm having a thickness of the outer surface rubber of about 1 to 1.5 mm, for example, in the conventional vent hole type cylindrical rubber mold, the following 1 . ~ 4. There was a problem. 1. The vent hole must have a diameter of at least 1 mm, and if the cover rubber is about 1 mm, the rubber near the vent hole will flow excessively, causing adhesion failure with the cord, and sometimes the cord may be exposed. there were. Also, the cover rubber may become thin and not serve as a cover.

  2. In the shape that rapidly reduces the diameter, the air that should be discharged from the general diameter of the central part must be concentrated and discharged from the reduced diameter surface, but even if many small vent holes are provided, the discharge effect is not improved much, The air escape was not good. In particular, when the length in the axial direction is L and the length in the radial direction is R, this is remarkable in the mold of the diaphragm for an air spring in which L / R exceeds 1.5. 3. It was necessary to individually clean the rubber clogged in the vent hole, which required a great amount of man-hours. 4). The trace of the vent hole was deteriorating the product appearance (product value).

  In the present invention, the conventional problems are achieved by the structure in which the air of the entire reduced diameter surface is discharged through the plurality of ring dies 5-9. ~ 4. Could be solved at once. In other words, only air is discharged and rubber does not protrude between the ring molds. The pitch (thickness) of the ring molds can be set to be thicker or thinner depending on the product shape. In addition, the distance between the ring-shaped joints in the axial direction (interval in the direction of the axis P of the horizontal groove gy) becomes wider as it goes to the end in the direction of the axis P. There is.

  Since the amount of rubber protrusion is small, the number of finishing steps for the product is small, and the frequency of cleaning the mold is reduced. In addition, although a split surface remains on the circumference as a diaphragm, the traces are uniform over the entire circumference, so that the appearance and appearance are not impaired. That is, it can be said that the invention is a cylindrical rubber molding die that exhibits excellent effects that can improve quality, cost, and product aesthetics.

[Another Example]
The number of the ring dies r may be 1 or more when there is an enclosure type kg, and may be 2 or more when there is no enclosure type kg. Any configuration having a surface is sufficient. The pitch of the ring type r can be increased or decreased depending on the shape and size of the product (diaphragm for air spring).

5d to 9d Tapered outer peripheral surface 17 to 21 Tapered inner surface D Cylindrical rubber M Molded surface P Axis bk Auxiliary path bt Air discharge path kg Enclosed type kt Type end r Ring type s Reduced diameter surface

Claims (6)

In order to surround and receive the cylindrical rubber that is pressurized and expanded from the inside, it has a reduced diameter surface that is reduced in diameter so that the diameter decreases as the end in the axial direction approaches the end in the axial direction. A cylindrical rubber mold having a tapered cylindrical molding surface,
A mold for cylindrical rubber, in which a die end portion forming the reduced diameter surface is formed by stacking a plurality of flat ring dies having a smaller axial dimension than a radial dimension in the axial direction.   The reduction rate per unit axial length of the diameter of the diameter-reduced surface is set so as to increase toward the end in the axial direction, and the axial thicknesses of the plurality of ring types are mutually connected. The cylindrical rubber mold according to claim 1, which is set to an equal value.   The cylindrical rubber mold according to claim 1, further comprising an outer mold that accommodates and holds the plurality of ring molds.   The said surrounding mold is a bowl-shaped thing centering on the said shaft center, The taper inner surface fitted to the taper outer peripheral surface of the said ring type is formed corresponding to every said several ring type | mold. A mold for cylindrical rubber as described in 1.   The cylindrical rubber molding die according to claim 3 or 4, wherein an auxiliary passage for air discharge extending in a radial direction with respect to the shaft center is formed between adjacent ones of the plurality of ring dies.   The cylindrical rubber molding die according to claim 5, wherein an air discharge path extending along the axial direction is formed between the plurality of ring molds and the surrounding mold in a state following the auxiliary path.

Images