Cylindrical Unvulcanized Rubber Member, Method for Producing the Same, and Method for Producing Rubber Hose

Abstract

To provide a cylindrical unvulcanized rubber member capable of suppressing the occurrence of an inner surface bear, a method for manufacturing the same, and a method for manufacturing a rubber hose.SOLUTION: A method for manufacturing a cylindrical unvulcanized rubber member 1 comprises: an inner surface rubber layer formation step of spirally winding an unvulcanized rubber tape around an outer circumferential surface of a mandrel B so that a first side surface 8 of the unvulcanized rubber tape comes into contact with the outer circumferential surface of the mandrel B and a second side surface 9 of the unvulcanized rubber tape constitutes an outer circumferential surface of an inner surface rubber layer 2 to form the cylindrical inner surface rubber layer 2 having a spiral recess 11 on the outer circumferential surface; and a reinforcing rubber layer formation step of spirally winding a cord coated with a vulcanized rubber around the outer circumferential surface of the inner surface rubber layer 2 to form a reinforcing rubber layer 3. After the reinforcing rubber layer formation step, a space 14 surrounded by the recess 11 and the reinforcing rubber layer 3 is formed on the outer circumferential surface of the inner surface rubber layer 2.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a tubular unvulcanized rubber member before vulcanizing a rubber hose such as a pumping tube used for pumping fresh concrete, a method for manufacturing the same, and a method for manufacturing a rubber hose.

Background Art

[0002] A rubber hose such as a pumping tube is manufactured by vulcanizing a tubular unvulcanized rubber member. As a method for vulcanizing a tubular unvulcanized rubber member, a vulcanization molding method of a cloth winding type is often adopted in which the tubular unvulcanized rubber member is formed on the outer peripheral surface of a mandrel, and the outer periphery of the tubular unvulcanized rubber member is tightened with cloth and directly vulcanized with steam. However, when the vulcanization molding method of the cloth winding type is adopted, there are problems that the productivity of the rubber hose is low and the appearance is deteriorated because cloth winding marks remain on the surface of the product.

[0003] As a vulcanization molding method of a rubber hose for solving the above problems, as shown in Patent Document 1, a vulcanization molding method of an outer bag type is known. A vulcanization can is used for the outer bag type. FIG. 9 is a semi-cross-sectional view showing one aspect of vulcanizing a tubular unvulcanized rubber member by an outer bag method using a vulcanization can. As shown in the figure, an inner rubber layer 22, a reinforcing rubber layer 23, and an outer rubber layer 24 are laminated in this order on the outer peripheral surface of a mandrel B, whereby a tubular unvulcanized rubber member 21 is formed on the outer peripheral surface of the mandrel B. A tubular rubber bag E is disposed inside the vulcanization can D, and the mandrel B having the tubular unvulcanized rubber member 21 formed on its outer peripheral surface is inserted into the rubber bag E, and steam or warm water is supplied between the rubber bag E and the vulcanization can D and heated while being pressurized to perform vulcanization.

[0004] Thus, by using the outer bag method using the vulcanization can D, the outer peripheral surface of the rubber hose can be smoothed, and the productivity and dimensional accuracy can be improved. In particular, it is a suitable vulcanization molding method when vulcanizing a long and large-diameter tubular unvulcanized rubber member having a certain length to mass-produce a rubber hose.

Prior Art Documents

Patent Document

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, when vulcanizing and molding a cylindrical unvulcanized rubber member by an external bag method, in the vulcanization process, the unvulcanized rubber expands, and in some cases, as shown in FIG. 10, the rubber hose 25 bulges radially against the rubber bag E locally, and accordingly, there has been a problem that a dent called an inner surface bear 26 is generated on the inner surface of the rubber hose 25.

[0007]

Means for Solving the Problems

[0008] As a result of intensive studies to solve the above problems, the present inventor has found that by forming a space portion on the outer peripheral surface of the inner rubber layer, the expansion of the inner rubber layer in the vulcanization process can be absorbed by the space portion, and a rubber hose in which the space portion disappears while suppressing the inner surface bear when the vulcanization process is completed can be obtained, and thus the present invention has been completed.

[0009] That is, one aspect of the present invention is a method for manufacturing a cylindrical unvulcanized rubber member including an inner rubber layer and a reinforcing rubber layer formed on the outer peripheral surface of the inner rubber layer, Supply the unvulcanized rubber that constitutes the inner rubber layer to an extruding device, and wind the unvulcanized rubber tape extruded from the extruding device around the outer peripheral surface of a rotating mandrel in a spiral manner such that a first side surface of the unvulcanized rubber tape abuts against the outer peripheral surface of the mandrel and a second side surface of the unvulcanized rubber tape constitutes the outer peripheral surface of the inner rubber layer, thereby forming an inner rubber layer that is cylindrical and has a spiral recess on its outer peripheral surface; an inner rubber layer forming step A reinforcing rubber layer forming step of forming a reinforcing rubber layer by spirally winding a cord coated with unvulcanized rubber around the outer peripheral surface of the inner rubber layer; After the reinforcing rubber layer forming step, a space portion surrounded by the recess and the reinforcing rubber layer is formed on the outer peripheral surface of the inner rubber layer.

[0010] The second side surface of the unvulcanized rubber tape may be a curved surface that bulges outward.

[0011] The reinforcing rubber layer may be configured such that a plurality of rubber-coated cord layers made of cords coated with unvulcanized rubber are laminated, and adjacent rubber-coated cord layers are arranged such that the inclination angles of the cords intersect symmetrically with respect to the axial direction of the mandrel.

[0012] After the reinforcing rubber layer forming step, an outer rubber layer forming step of forming an outer rubber layer made of unvulcanized rubber on the outer peripheral surface of the reinforcing rubber layer may be provided.

[0013] The manufacturing method of the cylindrical unvulcanized rubber member described above may further include a vulcanizing step of vulcanizing the cylindrical unvulcanized rubber member, and the space portion disappears due to the expansion of the inner layer rubber layer in the vulcanizing step, which may be a manufacturing method of a rubber hose.

[0014] The cylindrical unvulcanized rubber member is cylindrical and has a spiral recess on its outer peripheral surface, and includes an inner rubber layer made of unvulcanized rubber and a reinforcing rubber layer made of a cord coated with unvulcanized rubber formed on the outer peripheral surface of the inner rubber layer, and a space portion surrounded by the recess of the inner rubber layer and the reinforcing rubber layer is formed.

[0015] The recess in the inner rubber layer of the cylindrical unvulcanized rubber member is substantially V-shaped, and one surface of the inner surface of the recess may be a curved surface bulging toward the space portion.

Advantages of the Invention

[0016] According to the method for manufacturing a cylindrical unvulcanized rubber member according to one aspect of the present invention, after the reinforcing rubber layer forming step, a space portion surrounded by the recess and the reinforcing rubber layer is formed on the outer peripheral surface of the inner rubber layer. Therefore, when the cylindrical unvulcanized rubber member is vulcanized, the expansion of the inner rubber layer can be absorbed by the space portion, and a rubber hose in which the space portion has disappeared while suppressing inner bearing can be obtained when the vulcanization step is completed.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Embodiments for Carrying Out the Invention

[0018] Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a semi-sectional view of the cylindrical unvulcanized rubber member of the present invention formed on the outer peripheral surface of a mandrel, FIG. 2 is an enlarged view of the portion surrounded by the frame A in FIG. 1, FIG. 3 is a perspective view showing one aspect of a method for forming the inner rubber layer of FIG. 1, FIG. 4 is a partial cross-sectional view of the inner rubber layer shown in FIG. 3, and FIG. 5 is a cross-sectional view of the unvulcanized rubber tape constituting the inner rubber layer of FIG. 1. For convenience, the hatching of the cross-section of the inner rubber layer in FIGS. 1, 2, 4, and 5 is omitted.

[0019] As shown in FIG. 1, the cylindrical unvulcanized rubber member 1 of the present embodiment is formed on the outer peripheral surface of a mandrel B. The cylindrical unvulcanized rubber member 1 includes an inner rubber layer 2, a reinforcing rubber layer 3 formed on the outer peripheral surface of the inner rubber layer 2, and an outer rubber layer 4. Hereinafter, a method for manufacturing the cylindrical unvulcanized rubber member 1 will be described.

[0020] There is no particular limitation on the base formulation of the unvulcanized rubber used for the inner rubber layer 2, the reinforcing rubber layer 3, and the outer rubber layer 4, and any formulation known in the art can be used. For example, natural rubber (NR), styrene-butadiene rubber (SBR), or a blend composition of NR and cis-1,4-polybutadiene rubber (BR) and / or SBR, which are excellent in abrasion resistance, water resistance, and processability, can be mentioned.

[0021] As shown in FIGS. 3 and 4, the unvulcanized rubber constituting the inner rubber layer 2 is supplied to an extruder C, and the unvulcanized rubber tape 5 extruded from the extruder C is spirally wound around the outer peripheral surface of the rotating mandrel B to form the inner rubber layer 2 (inner rubber layer forming step). To explain the inner rubber layer forming step in detail, as shown in FIG. 5, the unvulcanized rubber tape 5 includes a first surface 6 and a second surface 7 extending parallel to the tape width direction W, and a first side surface 8 and a second side surface 9 connecting between the first surface 6 and the second surface 7. The first side surface 8 is an inclined surface inclined with respect to the first surface 6 and the second surface 7. The second side surface 9 is a curved surface bulging outward in the tape width direction, and its cross-sectional shape is substantially arc-shaped as shown in FIG. 5.

[0022] The uncured rubber tape 5 with the above structure is spirally wound around the outer peripheral surface of the mandrel B such that the first side surface 8 of the uncured rubber tape 5 abuts against the outer peripheral surface of the mandrel B and the second side surface 9 of the uncured rubber tape 5 constitutes the outer peripheral surface of the inner rubber layer 2. As a result, as shown in FIG. 1, the uncured rubber tape 5 is laminated in a state where its width direction is inclined at an angle α with respect to the axial direction of the mandrel B, and finally, an inner rubber layer 2 having a cylindrical shape, a smooth inner peripheral surface, and a spiral recess 11 on the outer peripheral surface can be formed.

[0023] After the inner rubber layer forming step, a reinforcing rubber layer 3 is formed by spirally winding a cord coated with uncured rubber around the outer peripheral surface of the inner rubber layer 2 (reinforcing rubber layer forming step). To explain the reinforcing rubber layer forming step in detail, the reinforcing rubber layer 3 is formed by laminating an even number of rubber-coated cord layers 13 made of a sheet-like material obtained by topping a known uncured rubber on a warp knitted fabric (cord 12) made of fibers. Examples of the fibers used for the cord include organic fibers such as rayon, nylon, polyester, aramid, and carbon, and inorganic and metal fibers such as glass and steel.

[0024] In this embodiment, two rubber-coated cord layers 13 are laminated, and the adjacent rubber-coated cord layers 13, 13 are arranged such that the inclination angles of the cords 12 intersect symmetrically with respect to the axial direction of the mandrel B. After the reinforcing rubber layer forming step, an outer rubber layer 4 made of uncured rubber is formed on the outer peripheral surface of the reinforcing rubber layer 3 (outer rubber layer forming step). Although the formation of the outer rubber layer 4 is not necessarily required, it has the effect of protecting the reinforcing rubber layer 3, improving the durability of the rubber hose, and having excellent aesthetics.

[0025] The cylindrical uncured rubber member 1 thus obtained has a cylindrical shape with a spiral recess 11 on its outer peripheral surface, and includes an inner rubber layer 2 made of uncured rubber and a reinforcing rubber layer 3 made of a cord coated with uncured rubber formed on the outer peripheral surface of the inner rubber layer 2. As shown in FIG. 2, a space portion 14 surrounded by the recess 11 of the inner rubber layer and the reinforcing rubber layer 3 is formed. The recess 11 has a substantially V-shaped cross section, and one surface of the inner surface of the recess 11 is a curved surface 9 that bulges toward the space portion 14.

[0026] Regarding the shape of the unvulcanized rubber tape 5, conventionally, as shown in FIG. 6, the second side surface 29 was formed in a V-shaped cross section protruding outward. As a result, as shown in FIG. 9, when the reinforcing rubber layer 23 was formed on the outer peripheral surface of the inner rubber layer 22, the portion of the second side surface 29 collapsed and the outer peripheral surface of the inner rubber layer 22 was smoothed, thereby enhancing the adhesion between the inner rubber layer 22 and the reinforcing rubber layer 23.

[0027] On the other hand, in the present invention, as shown in FIG. 5, the second side surface 9 of the unvulcanized rubber tape 5 is formed to be curved. As a result, as shown in FIG. 2, the reinforcing rubber layer 3 is in contact with the curved surface of the second side surface 9 of the unvulcanized rubber tape 5. Therefore, when the reinforcing rubber layer 3 is pressed against the inner rubber layer 2, the recess 11 is held without being crushed by the curved shape of the second side surface 9.

[0028] The cylindrical unvulcanized rubber member 1 obtained as described above is inserted into the vulcanizing can D together with the mandrel B as shown in FIG. 7. Then, vulcanization is performed by supplying steam or warm water between the rubber bag E and the vulcanizing can D and heating while applying pressure. At this time, since the space portion 14 surrounded by the recess 11 and the reinforcing rubber layer 3 is formed on the outer peripheral surface of the inner rubber layer 2, the expansion of the inner rubber layer 2 can be absorbed by the space portion 14 when the cylindrical unvulcanized rubber member 1 is vulcanized. As a result, as shown in FIG. 8, a rubber hose 15 in which the space portion 14 has disappeared while suppressing the inner bulge can be obtained at the end of the vulcanization process.

[0029] The thickness T of the unvulcanized rubber tape 5 may be 1.0 mm or more from the viewpoints of strength and forming a space portion with an appropriate volume, preferably 1.5 mm or more, and more preferably 2.0 mm or more. Also, the thickness T of the unvulcanized rubber tape 5 may be 4.0 mm or less from the viewpoints of handleability and suppressing the formation of a space portion with an excessive volume, preferably 3.5 mm or less, and more preferably 3.0 mm or less.

[0030] Although the embodiments of the present invention have been described above, the scope of the present invention is not limited thereto, and various modifications can be made without departing from the spirit of the invention. Specifically, in the present embodiment, the outer rubber layer 4 is provided on the outer surface of the reinforcing rubber layer 3, but the outer rubber layer 4 may not be provided. In addition, the constituent elements disclosed in the present embodiment can be combined with each other, and by combining them, new technical features can be formed.

Explanation of Reference Numerals

[0031] 1 Tubular unvulcanized rubber member 2 Inner rubber layer 3 Reinforcing rubber layer 4 Outer rubber layer 5 Unvulcanized rubber tape 6 First surface 7 Second surface 8 First side surface 9 Second side surface 11 Recess 12 Cord 13 Rubber-coated cord layer 14 Space part 15 Rubber hose B Mandrel C Extrusion device D Vulcanizing can E Rubber bag

Claims

1. A method for manufacturing a cylindrical unvulcanized rubber member including an inner rubber layer and a reinforcing rubber layer formed on the outer peripheral surface of the inner rubber layer, supplying the unvulcanized rubber constituting the inner rubber layer to an extruder, and winding the unvulcanized rubber tape extruded from the extruder around the outer peripheral surface of a rotating mandrel in a spiral manner such that a first side surface of the unvulcanized rubber tape contacts the outer peripheral surface of the mandrel and a second side surface of the unvulcanized rubber tape constitutes the outer peripheral surface of the inner rubber layer, thereby forming an inner rubber layer having a cylindrical shape and a spiral recess on its outer peripheral surface; an inner rubber layer forming step, and a reinforcing rubber layer forming step of forming a reinforcing rubber layer by spirally winding a cord coated with unvulcanized rubber around the outer peripheral surface of the inner rubber layer, wherein the reinforcing rubber layer is formed by laminating a plurality of rubber-coated cord layers made of cords coated with the unvulcanized rubber, A method for manufacturing a cylindrical unvulcanized rubber member, in which a space portion surrounded by the recess and the reinforcing rubber layer is formed on the outer peripheral surface of the inner rubber layer after the reinforcing rubber layer forming step.

2. The method for manufacturing a cylindrical unvulcanized rubber member according to claim 1, wherein the second side surface of the unvulcanized rubber tape is a curved surface bulging outward.

3. The method for manufacturing a cylindrical unvulcanized rubber member according to claim 1 or 2, wherein in the reinforcing rubber layer, adjacent rubber-coated cord layers are arranged such that the inclination angles of the cords intersect symmetrically with respect to the axial direction of the mandrel.

4. The method for manufacturing a cylindrical unvulcanized rubber member according to any one of claims 1 to 3, further comprising an outer rubber layer forming step of forming an outer rubber layer made of unvulcanized rubber on the outer peripheral surface of the reinforcing rubber layer after the reinforcing rubber layer forming step.

5. A method for manufacturing a rubber hose, comprising a vulcanization step of vulcanizing a cylindrical unvulcanized rubber member obtained by the method for manufacturing a cylindrical unvulcanized rubber member according to any one of claims 1 to 4, wherein the space portion disappears due to the expansion of the inner layer rubber layer in the vulcanization step.

6. A cylindrical unvulcanized rubber member having a spiral recess on its outer peripheral surface, comprising an inner rubber layer made of unvulcanized rubber and a reinforcing rubber layer made of cords coated with unvulcanized rubber formed on the outer peripheral surface of the inner rubber layer. The reinforcing rubber layer is formed by laminating a plurality of rubber-coated cord layers made of cords coated with unvulcanized rubber, and a space portion surrounded by the recess of the inner rubber layer and the reinforcing rubber layer is formed.

7. The cylindrical unvulcanized rubber member according to claim 6, wherein the recess is substantially V-shaped, and one surface of the inner surface of the recess is a curved surface bulging toward the space portion.

Images