JP2007030270A - Manufacturing method of cylindrical body made of rubber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a rubber made cylindrical body (rubber hose) capable of enhancing the productivity, appearance and dimensional accuracy of the rubber made cylindrical body. <P>SOLUTION: An unvulcanized rubber cylinder 7 is arranged on the outer peripheral side of a cylindrical inner mold 4 and the outer peripheral surface of the inner mold 4 is constituted of the side surface of a truncated cone. The inner mold 4 on its small diameter side is externally fitted to a shaft 6 so as to be freely slid in its center axis direction and inserted in a cylindrical outer mold 5 on its large diameter side. The inner peripheral surface of the outer mold 5 is constituted of the side surface of a truncated cone. The inner mold 4 is pushed in the outer mold 5 toward its small diameter side and the movement of the inner mold 4 in the center axis direction of the end part on the large diameter side of the inner mold 4 is restricted with respect to the outer mold 5. The inner mold 4 is thermally expanded on its small diameter side by heat for vulcanizing molding to press an unvulcanized rubber cylinder 7 on its outer peripheral side to the inner peripheral surface of the outer mold 5. By this constitution, the unvulcanized rubber cylinder 7 is vulcanized and molded into the rubber hose 1 by the pressure and heating of the inner mold 4. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method of manufacturing a rubber cylinder for manufacturing a truncated cone-shaped rubber hose having different inner diameters and outer diameters at both ends.

  Generally, a rubber cylinder is manufactured by vulcanization molding by heating an unvulcanized rubber cylinder while pressing it from inside and outside. Of the rubber cylinders, for the manufacture of tires and air springs with a relatively small length ratio relative to the inner diameter, a bag is inserted inside the unvulcanized rubber cylinder, and the unvulcanized rubber is inserted under the pressure of the bag. In many cases, bag-type vulcanization molding in which a cylinder is pressed against an outer mold is employed (for example, Patent Document 1).

  However, even if a bag-type vulcanization molding is adopted for the production of a long rubber cylinder such as a rubber hose, it is difficult to insert and withdraw the bag, and the productivity is extremely lowered. Furthermore, when manufacturing a rubber hose in which fluid flows easily as a rubber cylinder, the inner circumference of the rubber cylinder that is pressed against a soft bag is likely to cause dimensional fluctuations, irregularities, and steps. In the case of manufacturing a slurry hose through which the slag flows, there is a risk of causing a problem in the product.

Therefore, for the production of long rubber cylinders such as rubber hoses, cloth-wrapped vulcanization is used, in which unvulcanized rubber and reinforcing fibers are laminated on a mandrel, and the outer periphery is tightened and directly steam vulcanized. Has been.
JP-A-6-23864

  However, when cloth-wrapping vulcanization molding is employed, the productivity of the rubber cylinder is low, the appearance of the product tends to deteriorate, and the dimensional accuracy of the product tends to be poor.

  An object of this invention is to provide the manufacturing method of the rubber cylinder which can improve the productivity, external appearance, and dimensional accuracy of a rubber cylinder.

  In order to achieve the above object, the manufacturing method according to the present invention manufactures a truncated cone-shaped rubber cylinder having different inner and outer diameters at both ends. The procedure will be described. First, an unvulcanized rubber cylinder is arranged on the outer peripheral side of a cylindrical inner mold having an outer peripheral surface made up of the side surface of the truncated cone, and the inner mold is externally fitted to the shaft for supporting the inner mold. . Next, the inner mold is inserted into the outer mold having the inner peripheral surface formed of the side surface of the truncated cone by aligning the outer mold with the large diameter side and the small diameter side. After that, by restricting the movement of the end of the large-diameter side of the inner mold in the direction of the central axis relative to the outer mold, the inner mold is thermally expanded to the small-diameter side by heat for vulcanization molding, and arranged on the outer peripheral side of the inner mold. The unvulcanized rubber cylinder is pressed against the inner peripheral surface of the outer mold and vulcanized.

  According to this configuration, when the vulcanization molding is performed, the outer peripheral surface of the inner mold that is thermally expanded and extends toward the small diameter side gradually approaches the inner peripheral surface of the outer mold. Can be pressurized. As a result, the shape and dimensions of the rubber cylinder can be stabilized, and residual air can be sufficiently eliminated to stabilize the physical properties of the rubber cylinder. Furthermore, since the inner and outer molds that pressurize the unvulcanized rubber cylinder have sufficient rigidity, the rubber cylinder can be made extremely without causing dimensional fluctuations, irregularities and steps as in the bag system and cloth winding system. It can be molded into a stable shape and size.

  In addition, since the outer peripheral surface of the inner mold and the inner peripheral surface of the outer mold are composed of the side surfaces of the truncated cone, the resistance when attaching and detaching the inner mold and the outer mold can be reduced, and the attachment and detachment can be made extremely easy. That is, when the inner mold is inserted into the outer mold before vulcanization molding, the unvulcanized rubber cylinder arranged on the outer peripheral side of the inner mold and the inner peripheral surface of the outer mold until the inner mold reaches a predetermined position. There is a clearance between them, and when the inner die is drawn after vulcanization molding, the rubber cylinder is separated from the inner die or the outer die almost simultaneously with the start of the drawing.

  Also, the inner mold outer peripheral surface and the outer mold inner peripheral surface that are inclined with respect to the central axis direction are brought close to each other by utilizing the movement in the central axis direction by freely expanding the inner mold. There is no need to set the strength of the inner mold, the outer mold and the shaft to be extremely large as in the technique of constraining both ends and inflating only in the radial direction. The shaft is a shaft-shaped member, and is a concept including a solid shaft-shaped member and a pipe-shaped shaft-shaped member.

  To thermally expand the inner mold and bring its outer peripheral surface closer to the inner peripheral surface of the outer mold, the inner mold is made of resin, the outer mold is made of steel having a smaller coefficient of thermal expansion than the inner mold, and the thermal expansion of both By inflating the inner mold to the smaller diameter side due to the difference in rate, a technique of pressing the unvulcanized rubber cylinder against the outer mold with the inner mold can be employed. The resin inner mold has a sufficiently larger coefficient of thermal expansion than the steel outer mold, and by combining these, the unvulcanized rubber cylinder can be strongly pressed. In addition, only the outer mold is heated in advance, the inner mold is pushed into the outer mold, and then only the inner mold is thermally expanded to bring the inner mold outer peripheral surface closer to the outer mold inner peripheral surface. Is possible.

  If an unvulcanized rubber cylinder is formed around the inner mold by using the inner mold as a mandrel, the process of forming the unvulcanized rubber cylinder in advance and attaching the unvulcanized rubber cylinder to the inner mold is omitted. can do.

  The present invention also provides a rubber cylinder manufactured in the shape of a truncated cone by the above manufacturing method. The rubber cylinder may be composed only of rubber. For example, a reinforcing fiber such as a steel cord is disposed between the inner rubber and the outer rubber so that the reinforcing fiber is embedded. A reinforcing fiber layer can be provided. In the above production method, when vulcanization molding is performed, the unvulcanized rubber cylinder can be pressurized almost uniformly over the whole, so that it is difficult to cause non-uniform flow of the unvulcanized rubber, and the reinforcing fiber is Even if it is an embedded structure, the displacement of the reinforcing fiber can be eliminated.

  Rubber cylinders in which the ratio (L / D) of the length (L) in the central axis direction to the inner diameter (D) of the large-diameter end is set to 8 to 40 are difficult to adopt bag-type vulcanization molding. It is a rubber cylinder of a scale, and is preferably manufactured by the above manufacturing method. Furthermore, a rubber cylinder in which (L / D) is set to 10 to 20, a rubber cylinder in which D is set to 50 mm to 300 mm, particularly a rubber cylinder in which D is set to 80 mm to 200 mm. The body is more preferably produced by the production method described above.

  The present invention also provides a vulcanization mold for vulcanizing and molding an unvulcanized rubber cylinder into a truncated cone-shaped rubber cylinder having different inner and outer diameters at both ends.

  Specifically, a cylindrical resin-made inner mold having an outer peripheral surface composed of side surfaces of a truncated cone and having an unvulcanized rubber cylinder disposed on the outer peripheral side, a shaft that supports the inner mold, and the truncated cone A vulcanization mold having a steel outer mold having an inner peripheral surface made of a side surface and having a smaller coefficient of thermal expansion than the inner mold, and the inner mold is externally fitted to the shaft to form the outer mold. The large diameter side and the small diameter side are inserted in the same direction, and the movement of the end of the large diameter side in the central axis direction with respect to the outer mold is restricted, and the difference in thermal expansion coefficient from the outer mold due to the heat for vulcanization molding , The unvulcanized rubber cylinder is pressed against the inner peripheral surface of the outer mold and vulcanized and molded.

  The inner mold may be slid directly on the surface of the shaft, but a pipe-like slide member such as a steel pipe may be interposed between the inner mold and the shaft. By sliding the inner mold more reliably with respect to the shaft, it is possible to reliably prevent the generation of frictional force that restrains the elongation of the inner mold.

  Since the entire outer peripheral surface of the unvulcanized rubber cylinder is brought into contact with the outer mold, heat is directly transferred from the outer mold to the unvulcanized rubber cylinder by providing a heating means for heating the unvulcanized rubber cylinder. And can be heated efficiently.

  As described above, according to the present invention, the inner mold having the outer peripheral surface composed of the side surface of the truncated cone is inserted into the outer mold having the outer peripheral surface composed of the side surface of the truncated cone, and the inner mold is thermally expanded to extend toward the smaller diameter side. Thus, the unvulcanized rubber cylinder is pressurized and vulcanized by the outer peripheral surface of the inner mold and the inner peripheral surface of the outer mold. As a result, it is possible to vulcanize and mold the unvulcanized rubber cylinder gradually and strongly with sufficiently rigid inner and outer molds, producing a rubber cylinder with extremely stable shape, dimensions and physical properties. can do. Also, the inner and outer molds can be easily attached and detached, and the productivity of the rubber cylinder can be increased.

  Hereinafter, the best mode for carrying out the method for producing a rubber cylinder according to the present invention will be described with reference to the drawings. FIG. 1 is a view showing a rubber hose manufactured by the manufacturing method according to the present invention, in which the lower half is a side view and the upper half is a cross-sectional view.

  The rubber hose 1 has an inner diameter (D1) that is larger than an inner diameter (D2) at one end, and a wall thickness (t) that is a truncated cone-shaped rubber cylinder that is constant over the entire circumference and length. A reinforcing fiber layer 2 in which steel cords as reinforcing fibers are embedded is provided between 1a and the outer rubber 1b. The dimensions of the rubber hose 1 are, for example, an inner diameter (D) of 50 mm to 300 mm, a central axial direction length (L) of 1000 mm to 5000 mm, and a central axial length (L) with respect to the inner diameter (D1) of one end (large diameter side end). The ratio (L / D1) is set to 8 to 40, and the wall thickness (t) is set to 10 mm to 30 mm.

  Next, a method for manufacturing the rubber hose 1 will be described. First, a vulcanization mold for vulcanizing the rubber hose 1 will be described. FIG. 2 is a cross-sectional view of a vulcanization mold used for vulcanization molding of a rubber hose.

  The vulcanization mold 3 supports a cylindrical inner mold 4 that forms the inner surface of the rubber hose 1 on the outer peripheral surface, a cylindrical outer mold 5 that forms the outer surface of the rubber hose 1 on the inner peripheral surface, and the inner mold 4. A shaft 6 is provided, and the unvulcanized rubber cylinder 7 is pressurized and vulcanized by the outer peripheral surface of the inner mold 4 and the inner peripheral surface of the outer mold 5.

  The inner mold 4 is made of, for example, a synthetic resin such as polypropylene (PP), and the outer diameter of one end and the other end is the inner diameter (D1) of one end (large diameter side end) of the rubber hose 1 and the inner diameter of the other end (small diameter side end). (D2) is set equal to each other, and the outer peripheral surface constitutes the side surface of the truncated cone. An inner diameter of the inner die 4 is set to be constant in the central axis direction and slightly larger than an outer diameter of the shaft 6, and the inner die 4 is fitted on the shaft 6.

  The outer mold 5 is a steel cylinder in which a cavity 8 for injecting a heat medium is formed all around the outer mold 5, and a heat medium such as silicon oil or glycerin is supplied at a low pressure from the inlet 9 into the cavity 8. It has become. The inner diameter of one end and the other end of the outer mold 5 is set equal to the outer diameter (D1 + t) of one end (large-diameter side end) and the outer diameter (D2 + t) of the other end (small-diameter side end) of the rubber hose 1, respectively. The inner peripheral surface of 5 constitutes the side surface of the truncated cone. The outer diameter of the outer mold 5 is set to be constant in the central axis direction. The outer mold 5 shown in FIG. 2 is configured by connecting three divided bodies 5a, 5b, and 5c with bolts 10 in the central axis direction.

  The shaft 6 is a steel pipe whose outer diameter is constant in the center axis direction and whose center axis direction length is set longer than that of the inner mold 4 and the outer mold 5, and a flange 11 projecting in a direction perpendicular to the axis near one end thereof. Is fixed by welding. The flange 11 is configured such that one end (large diameter side end) of the outer mold 5 is bolted and the movement of the inner mold 4 to one end side (large diameter side) is restricted.

  Next, a procedure for manufacturing the rubber hose 1 using the vulcanization mold 3 will be described. FIG. 3 is a schematic diagram showing vulcanization molding of a rubber hose. (A) shows a state before vulcanization molding, and (b) shows a state after vulcanization molding. The vulcanization mold 3 in FIG. 3 is a simplified illustration of the vulcanization mold 3 shown in FIG. 2, and the outer mold 5 has a constant outer diameter that is changed in the direction of the central axis. The flange 11 is shown integrally with one end of the shaft 6.

  First, an inner surface unvulcanized rubber is wound around the outer side of the inner mold 4, and two layers of steel cords are arranged so that the bias directions intersect each other on the outer side, and the outer surface unvulcanized rubber is wound around the outer side, An unvulcanized rubber cylinder 7 is formed on the outer peripheral side of the inner mold 4. While holding the unvulcanized rubber cylinder 7, the inner die 4 is fitted onto the shaft 6, and one end (large diameter side end) of the inner die 4 is brought into contact with the flange 11 of the shaft 6.

  Next, the inner mold 4 is inserted into the outer mold 5 from one end side while being fitted on the shaft 6, and the outer peripheral surface of the inner mold 4 and the inner peripheral surface of the outer mold 5 that are inclined with respect to the central axis direction are brought close to each other. The unvulcanized rubber cylinder 7 is brought into close contact with the mold 4 and the outer mold 5. That is, the inner mold 4 is inserted into the outer mold 5 so that the directions of the large diameter side and the small diameter side are aligned, and the unvulcanized rubber cylinder 7 on the outer peripheral side of the inner mold 4 is pressed against the inner peripheral surface of the outer mold 5.

  At this time, the movement of one end (large diameter side end) of the inner mold 4 to one end side (large diameter side) is restricted by the flange 11 of the shaft 6. Further, by bolting one end (large diameter side end) of the outer mold 5 to the flange 11, the movement of one end (large diameter side end) of the inner mold 4 relative to the outer mold 5 in the direction of the central axis is restricted. The state (a) is obtained.

  Thereafter, a heat medium such as silicon oil or glycerin is fed into the cavity 8 from the injection port 9 at a low pressure, and the heat medium is circulated while being heated by a heater to heat the outer mold 5. The heating medium may be any type such as high-pressure steam, and the outer mold 5 can be directly heated with a heat transfer heater without using a heating medium.

  The heat of the outer mold 5 is transferred to the inner mold 4 through the unvulcanized rubber cylinder 7, and the inner mold 4 is thermally expanded, so that the inner mold 4 whose movement at one end (large-diameter side end) is restricted to the other. The other end extends to the other end side (smaller diameter side) along the parallel portion 13 near the other end of the outer mold 5. The outer mold 5 also thermally expands. However, the inner mold 4 is positioned at the other end relative to the outer mold 5 due to the difference in thermal expansion coefficient between the resin that forms the inner mold 4 and the steel that forms the outer mold 5. Thermal expansion to the side (small diameter side).

  As shown in FIG. 3 (b), the inner mold 4 is thermally expanded and extends to the other end side (small diameter side), so that the outer peripheral surface of the inner mold 4 inclined with respect to the central axis direction is the inner mold 5. Along with this, a force is generated that presses the unvulcanized rubber cylinder 7 in the direction of the arrow 14 and pressurizes it. The outer peripheral surface of the inner mold 4 uniformly and gradually moves the unvulcanized rubber cylinder 7 with a strong and stable force while sufficiently flowing the unvulcanized rubber without causing a deviation of the steel cord to eliminate residual air. Pressurize.

  In this way, by heating the unvulcanized rubber cylinder 7 while pressing the unvulcanized rubber cylinder 7 between the inner mold 4 and the outer mold 5, the inner unvulcanized rubber and the outer unvulcanized rubber are vulcanized. Mold.

  After completion of the vulcanization molding, the inner mold 4 and the shaft 6 are drawn to one end side (large diameter side) and released. At this time, the inner mold 4 and the rubber hose 1 are thermally expanded. However, since the inner mold 4 and the outer mold 5 are truncated cones, a reaction force is acting between the inner mold 4 and the inner mold 4. 4 and the shaft 6 can be easily released without cooling. By the above manufacturing method, the rubber hose 1 having smooth and highly accurate rubber characteristics and dimensional characteristics is obtained.

  Next, the manufacturing method according to the present invention is compared with the conventional manufacturing method. Table 1 is a table showing a comparison between the manufacturing method according to the present invention and three conventional manufacturing methods.

  Among conventional manufacturing methods, A is a manufacturing method using cloth-wrapping vulcanization molding (cloth-wrapping vulcanization), in which an inner surface unvulcanized rubber, a steel cord and an outer surface unvulcanized rubber are laminated on a mandrel. This is a manufacturing method in which an unvulcanized rubber cylinder is formed, and the outer peripheral side thereof is cloth-capped and directly steam vulcanized.

  B is a manufacturing method using bag-type vulcanization molding (inner bag outer mold vulcanization). The bag is inserted into an unvulcanized rubber cylinder removed from the molding drum, and divided into two long outer molds. It is a manufacturing method that is set and press vulcanized.

  C is a manufacturing method in which the inside and outside of the bag and mold of B are reversed (bag vulcanization outside the mandrel), an unvulcanized rubber cylinder is formed around the mandrel, and this is mounted inside the vulcanizing can This is a method of inserting into a bag, applying external pressure to the bag, and pressurizing and vulcanizing from the outside.

  The dimensions of the rubber hose 1 manufactured by these manufacturing methods are as follows. The length in the central axis direction is 3000 mm, the inner diameter of the large diameter end is φ136, the inner diameter of the small diameter end is φ115, the outer diameter of the large diameter end is φ188, and the small diameter side The outer diameter of the end is φ167. The inner rubber 1a and the outer rubber 1b are 55-degree natural rubber, and two reinforcing steel cords that cross each other are embedded in the reinforcing fiber layer 2 at a bias angle of 55 °. The vulcanization conditions in the present invention and the conventional production method are all 160 ° C. × 70 minutes.

  As Table 1 shows, as for capital investment, the conventional manufacturing method (A, B, C) requires a vulcanizing can, and furthermore, the manufacturing method B is divided into two expensive molds and vulcanizing press (bag). Manufacturing method C requires a dedicated bag vulcanization facility (vulcanized can with bag), whereas the present invention vulcanizes and molds with an inexpensive inner die (conical frustum cylinder) and outer die. be able to.

  In addition, when comparing the quality of the manufactured rubber hose 1, the inner diameter accuracy, outer diameter accuracy, appearance (appearance), productivity, fiber angle (displacement of steel cord), and air remaining are among the six items: inner diameter accuracy or outer diameter. It can be seen that the present invention is superior to the conventional manufacturing methods (A, B, C) except that any of the accuracy is of comparable quality.

  According to the above configuration, the unvulcanized rubber cylinder 7 is vulcanized and molded by pressurizing with the sufficiently rigid inner mold 4 and outer mold 5, so that a large and very expensive bag is unnecessary, and the bag Compared with the vulcanization molding of the method or the cloth winding method, the size of the rubber hose 1 can be extremely stabilized. In particular, even when a wear-resistant hose that pumps the slurry fluid is manufactured, it is possible to prevent dimensional fluctuations that cause the slurry fluid to be blocked or have an abnormal flow velocity.

Since the inner mold 4 made of synthetic resin and the outer mold 5 made of steel are used, the unvulcanized rubber cylinder 7 is changed to the outer mold 5 by using the difference in coefficient of thermal expansion even when both are heated. Can be pressed. Specifically, the linear expansion coefficient of the steel material is 11 to 16 × 10 ⁻⁶ / ° C., and the linear expansion coefficient of the synthetic resin (polypropylene, PP) is 8 to 11 × 10 ⁻⁵ / ° C. The linear expansion coefficient is 7 to 10 times the linear expansion coefficient of the steel material.

When the rubber hose 1 having a total length of 3000 mm is manufactured, if the temperature of incorporation into the vulcanization mold 3 is set to 20 ° C. and the vulcanization temperature is set to 160 ° C., the amount of elongation in the central axis direction of the inner mold 4 is 8 × 10 ⁻⁵ / Since the elongation amount in the direction of the central axis of the outer mold 5 is 11 × 10 ⁻⁶ / ° C. × 3000 × (160-20) = 4.6 mm at a temperature of × 3000 × (160−20) = 33.6 mm, Therefore, the inner mold 4 extends 29 mm.

  Since the inner mold 4 gradually expands as the temperature rises, the unvulcanized rubber flows uniformly and sufficiently without causing separation between the inner mold 4 and the outer mold 5 and the rubber and displacement of the reinforcing fibers. Thus, residual air that is likely to be generated in the laminate with the reinforcing fiber layer 2 can be eliminated.

Comparing the area of the specific cross section of the rubber hose 1 before and after vulcanization, for example, the unvulcanized rubber is strongly pressed while spreading between the inner mold 4 and the outer mold 5 so that 13000 mm ² before vulcanization is It becomes 12459 mm ² during vulcanization. Thereby, it compresses to 96% of the original volume during vulcanization, and moisture and air can be sufficiently eliminated by a compression amount of 4%.

  In other words, a total of 1.5% to 2% of moisture and air remain in ordinary unvulcanized rubber, and it is necessary to discharge this during vulcanization molding. Further, the unvulcanized rubber cylinder 7 is set to be at least about 1% smaller than the space between the inner mold 4 and the outer mold 5 so that it can be easily inserted into the outer mold 5. It is necessary to set the compression amount of rubber to 3% or more in total. On the other hand, since the compression amount is 4%, moisture and air can be sufficiently eliminated.

  If the amount of compression greatly exceeds 5%, the structure having the reinforcing fiber layer 2 causes irregular fluctuations in the arrangement of the reinforcing fibers, resulting in a decrease in pressure resistance or abnormal deformation during pressurization. In the rubber-only structure without the layer 2, excess rubber is discharged from the vulcanization mold gap or vent hole.

  Since the outer peripheral surface of the inner mold 4 and the inner peripheral surface of the outer mold 5 are composed of side surfaces of the truncated cone and are inclined with respect to the central axis direction, the inner mold 4 can be easily attached to and detached from the outer mold 5 and is long. A long rubber hose 1 can also be easily manufactured. Furthermore, since it is not necessary to cool the inner mold 4 and the shaft 6, the production cycle can be accelerated and the energy efficiency can be increased. Note that the polypropylene and nylon constituting the inner mold 4 do not fuse with rubber and can be easily removed without using a release agent or the like.

  Further, since the inner mold 4 is made of an inexpensive resin and the outer mold 5 does not need to be divided into two, it is possible to reduce the cost of the vulcanization mold 3 and eliminate the need for assembly and disassembly. The outer mold 5 is very thin compared to the vulcanized can, and can be made into a lightweight and inexpensive manufacturing facility.

  Since a heating medium such as silicon oil or glycerin is injected into the cavity 8 of the outer mold 5 and heated, high pressure steam pressure equipment such as a vulcanizing can can be dispensed with. At that time, the heat medium only needs to have heat energy for heating the outer mold 5 and does not need to be at a high pressure, so that it can be supplied at a low pressure. Further, since the entire outer peripheral surface of the unvulcanized rubber cylinder 7 is in direct contact with the outer mold 5 and receives heat conduction, the unvulcanized rubber cylinder 7 can be efficiently heated. Since the resin inner mold 4 does not come into direct contact with steam, it is less likely to deteriorate.

  In addition, this invention is not limited to said embodiment, A change can be suitably added within the scope of the present invention. For example, a pipe-shaped slide member may be interposed between the inner mold 4 and the shaft 6 so that the inner mold 4 can slide more reliably with respect to the shaft 6. In addition, the amount of thermal expansion of the inner mold 4 can be adjusted by adjusting the inner diameter of the inner mold 4 and the outer diameter of the shaft 6.

  The material of the inner mold 4 is not limited to polypropylene, but nylon 66 and other materials that can withstand vulcanization temperatures can be used, and heat-resistant rubber such as silicon rubber can also be used. Further, the coefficient of thermal expansion can be changed by changing the material of the inner mold 4.

  As means for heating the unvulcanized rubber cylinder 7, instead of injecting a heat medium into the outer mold 5, a heat medium is injected into the inner mold 4, or the entire vulcanization mold 3 is put in a vulcanizing can. It may be heated. Further, the rubber cylinder manufactured by the manufacturing method according to the present invention is not limited to the rubber hose 1, and any rubber product can be manufactured as long as it is a truncated cone-shaped cylinder.

The figure which shows the rubber hose manufactured by the manufacturing method which concerns on this invention Cross section of vulcanization mold used for rubber hose vulcanization molding Schematic diagram showing rubber hose vulcanization molding

Explanation of symbols

1 Rubber hose 2 Reinforcing fiber layer 3 Vulcanization mold 4 Inner mold 5 Outer mold 6 Shaft 7 Unvulcanized rubber cylinder

Claims (9)

  A manufacturing method for manufacturing a truncated cone-shaped rubber cylinder having different inner diameters and outer diameters at both ends, wherein an unvulcanized rubber cylinder is provided on the outer circumferential side of a cylindrical inner mold having an outer circumferential surface composed of side surfaces of the truncated cone. The inner mold is externally fitted to the shaft for supporting the inner mold, and then the outer mold and the outer mold having the inner peripheral surface composed of the side surfaces of the truncated cone are aligned with the outer mold and the large-diameter side and the small-diameter side. The inner mold is then inserted, and then the movement of the inner-diameter side end of the inner mold with respect to the outer mold in the central axis direction is restricted, and the inner mold is thermally expanded to the smaller-diameter side by heat for vulcanization molding. A method for producing a rubber cylinder, wherein the unvulcanized rubber cylinder disposed on the outer peripheral side of the inner mold is pressed against the inner peripheral surface of the outer mold and vulcanized.   The inner mold is made of resin, the outer mold is made of steel having a smaller coefficient of thermal expansion than the inner mold, and the inner mold is expanded to the smaller diameter side due to the difference in thermal expansion coefficient between the two, so that The method for producing a rubber cylinder according to claim 1, wherein the vulcanized rubber cylinder is pressed against an outer mold.   The method for producing a rubber cylinder according to claim 1 or 2, wherein the unvulcanized rubber cylinder is formed around the inner mold by using the inner mold as a mandrel.   A rubber cylinder manufactured in the shape of a truncated cone by the manufacturing method according to claim 1, 2 or 3.   The rubber cylinder according to claim 4, further comprising a reinforcing fiber layer in which reinforcing fibers are embedded.   The rubber cylinder according to claim 4 or 5, wherein the ratio (L / D) of the length (L) in the central axis direction to the inner diameter (D) of the large-diameter side end is set to 8 to 40. . A vulcanization mold for vulcanizing and molding an unvulcanized rubber cylinder into a truncated cone-shaped rubber cylinder having different inner diameters and outer diameters at both ends, and having an outer peripheral surface composed of side surfaces of the truncated cone A cylindrical resin-made inner mold on which the unvulcanized rubber cylinder is disposed, a shaft that supports the inner mold, and an inner peripheral surface that is formed by a side surface of a truncated cone; With an outer mold made of steel with a small expansion coefficient,
The inner mold is externally fitted to the shaft and inserted into the outer mold with the orientation of the large diameter side and the small diameter side, and the movement of the large diameter side end portion in the central axis direction with respect to the outer mold is restricted, The unvulcanized rubber cylinder is pressed against the inner peripheral surface of the outer mold and vulcanized and molded by expanding to the small diameter side due to a difference in thermal expansion coefficient with the outer mold due to heat for vulcanization molding. Vulcanizing mold.   The vulcanization mold according to claim 7, wherein a pipe-like slide member is interposed between the inner mold and the shaft.   The vulcanization mold according to claim 7 or 8, wherein a heating means for heating the unvulcanized rubber cylinder is provided in the outer mold.

Images