JP4034881B2 - Manufacturing method of bellows - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a bellows, and more particularly, to a method for manufacturing a bellows that can reduce wrinkles (wrinkles) in a bellows-like wall surface portion and can improve product yield.
[0002]
[Prior art]
Rubber bellows are used for various purposes, and for the purpose of imparting high pressure resistance, bellows with a base fabric in which a base fabric is embedded in rubber have been developed. In addition, for example, in order to improve responsiveness for the purpose of using a vibration absorbing member of a precision measuring device, there is an increasing demand for a so-called thin bellows having a thin rubber thickness.
[0003]
The structure of the bellows generally includes a pair of opposing ring-shaped facing surface portions and a bellows-like wall surface portion (a bellows-like wall surface portion) provided so as to connect the outer peripheral edge portions of these facing surface portions to each other. A plurality of peaks are formed on the wall surface. When manufacturing a bellows having such a structure as a bellows with a base fabric, first, a preform of the bellows is molded with a mold using rubber before vulcanization.
[0004]
Next, for example, a plain-woven sheet-like base fabric is wound around the preform, and then the plain-woven sheet-like base fabric is heated and pressed in the mold to form the side-shaped bellows of the mold. Vulcanize while deforming into shape. During this vulcanization, the temporarily softened rubber material penetrates into the base fabric, so that the bellows after vulcanization molding has a structure in which the base fabric is embedded.
[0005]
[Problems to be solved by the invention]
However, when the base fabric-containing bellows is molded as described above, because there are peaks and valleys on the outer peripheral edge of the bellows, a portion that extends to the base fabric and a portion that does not extend occur, and two or more stages, In particular, in bellows-shaped bellows having three or more ridges, wrinkles are likely to occur, and the base fabric is deformed on the preform, which causes the preform to be scraped or scratched. There was a problem that the yield of the product was extremely bad.
[0006]
The present invention was created based on such a situation, and its purpose is to reduce the occurrence of wrinkles, rubber scraping, and rubber scratching associated with the mounting of the base fabric, and the product yield and work. An object of the present invention is to provide a bellows manufacturing method capable of improving the efficiency.
[0007]
[Means for Solving the Problems]
In order to solve such a problem, the bellows manufacturing method of the present invention is a tubular base fabric tubular body woven with wefts constituting the yarn in the bellows circumferential direction and warp yarns orthogonal to the weft yarns. The weft yarn has a heat shrinkage ratio of at least two or more, and a base cloth preparation step for preparing a base cloth tubular body having a belt-like body having two or more different heat shrinkage ratio properties, A pair of ring-shaped opposing surface portions arranged so as to perform, and an accordion-shaped wall surface portion having two or more peaks and one or more valleys provided so as to connect the outer peripheral edge portions of the opposing surface portions to each other; A preform molding process for molding an unvulcanized rubber bellows rubber preform with a mold, and a rubber preform formed by the preform molding process so as to cover the base cloth cylindrical body And when the base fabric tubular body is heat shrunk In, while the base fabric tubular body is embedded as a base fabric in the vicinity of the surface of the rubber preform viewed including the deposition vulcanization step of vulcanizing the rubber preform, said base fabric tubular body, the valleys It is configured such that the thermal contraction rate of the weft arranged so as to be located in the recessed portion of the part is set to be larger than the thermal contraction rate of the weft located at the top of the peak portion .
[0008]
The bellows manufacturing method of the present invention is a tubular base fabric tubular body woven with weft yarns constituting the yarn in the bellows circumferential direction and warp yarns orthogonal to the weft yarns, and the thermal contraction rate of the weft yarns Are at least two types, and a pair of base fabric preparation steps for preparing a base fabric cylindrical body provided with a strip-shaped body having two or more different heat shrinkage rate physical properties, and a pair of them arranged to face each other An unvulcanized rubber comprising: a ring-shaped facing surface portion; and a bellows-like wall surface portion having two or more peaks and one or more valleys provided so as to connect the outer peripheral edge portions of the facing surface portion to each other. A preform molding step for molding a bellows rubber preform with a mold, and the base fabric cylindrical body placed on the rubber preform formed by the preform molding process so as to cover the base fabric cylindrical body. The base fabric cylindrical body with rubber While embedded near the surface of the record form as the base fabric, looking contains a deposition vulcanization step of vulcanizing the rubber preform, said base fabric tubular body, so as to be positioned in a recess portion near the valley A first belt-like body disposed and a second belt-like body disposed so as to be positioned in the vicinity of the top of the peak, and the second belt-like body has a thermal shrinkage rate of the weft yarn of the first belt-like body It is comprised so that it may become larger than the thermal contraction rate of this weft .
[0010]
Further, in the present invention, the base cloth cylindrical body includes a third belt-like body disposed so as to be positioned on the ring-shaped facing surface portion, and the thermal contraction rate of the weft of the third belt-like body Is set to be larger than the thermal contraction rate of the weft yarn of the second belt-like body.
[0011]
In the present invention, the rubber preform is vulcanized after heat shrinkage of the base cloth cylindrical body.
[0012]
Moreover, as a more preferable aspect of the present invention, the rubber preform is vulcanized at the same time as the thermal shrinkage of the base cloth cylindrical body.
[0013]
Further, as a more preferable aspect of the present invention, the band-shaped body in which the thermal shrinkage rate of the weft yarn of the base cloth cylindrical body is set larger is compared with the belt-shaped body in which the heat shrinkage rate is set to be small. The number is set small.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0015]
Bellows <br/> Figure 1 formed by the manufacturing method of the present invention is a perspective view showing an embodiment of a bellows of the present invention, FIG. 2 is a plan view of the bellows shown in FIGS. 1, 3 It is AA arrow half-section view of the bellows shown by FIG. 1 to 3, a bellows 1 according to the present invention is configured so that a pair of opposed ring-shaped rubber facing surface portions 2A and 2B and outer peripheral edge portions of the facing surface portions 2A and 2B are connected to each other. And a rubber bellows-like wall surface portion 3 provided.
[0016]
Each of the opposing surface portions 2A and 2B has a ring-shaped flat plate shape, and has an opening 4 as a preferable aspect at the center portion, and a bead portion 5 is formed inside the inner peripheral edge portion. Furthermore, in this embodiment, a yarn beat 5 a is formed on the innermost surface of the bead portion 5. In principle, even if there is no opening 4, for example, it can be combined with other parts (metal parts), but the opening 4 is necessary in consideration of workability, assembly, structure, and the like. If the opening 4 is present, a form corresponding to it is necessary in order to ensure particularly a sealing property after assembling or to ensure a concentricity between the bellows and other parts. The structure of the bead portion 5 in the present embodiment is a structure in which such consideration has been made, and since the base fabric 10 described later has entered the tip of the bead portion 5 facing inward, when pressed, The cloth due to tension is difficult to come off. This point, sealability, concentricity, etc. are satisfactory. Further, the yarn beat 5a is formed in order to further increase the sealing performance, that is, to increase the partial surface pressure of the bead portion.
[0017]
In the present embodiment, the bellows-like wall surface portion 3 includes a plurality of peak portions 3a (three peak portions in the illustrated example) and valley portions 3b (two valley portions in the illustrated example) positioned between the peak portions 3a. have. And in this bellows 1, the continuous base fabric 10 is embedded in the opposing surface portions 2A and 2B and the bellows-like wall surface portion 3 (FIG. 3).
[0018]
The preferred base fabric 10 used in the present invention is composed of a cylindrical base fabric tubular body woven with warp and weft yarns before being attached to the bellows 1, and the thermal shrinkage rate of the weft yarns is at least 2. More than two kinds of materials are used, and two or more kinds of belts having different heat shrinkage properties are provided.
[0019]
FIG. 4 (a) shows a preferred schematic perspective view of the base cloth cylindrical body 10 ′ before being attached to the bellows 1, and FIG. 4 (b) shows the base cloth cylindrical body 10 after being attached. A schematic perspective view of a state in which 'has undergone a predetermined heat shrinkage at a predetermined position and changed into a shape similar to the bellows shape of the bellows 1 is shown. Each hatch (hatched line) on the drawing shown in FIG. 4 is used to distinguish each band-like body described later.
[0020]
In FIG. 4A, a cylindrical base cloth cylindrical body 10 ′ includes a third belt-like body 10c arranged at the upper and lower ends thereof, and a second belt-like shape sequentially arranged in the vertical direction from these positions. The body 10b and the 1st strip | belt-shaped body 10a are provided. The first belt-like body 10a is arranged so as to be located in the vicinity of the depression of the valley 3b constituting the bellows, and the second belt-like body 10b is located near the top of the peak 3a constituting the bellows. Be placed. Moreover, the 3rd strip | belt-shaped body 10c is arrange | positioned so that it may be located in the said ring-shaped opposing surface part 2A and 2b which comprise a bellows. Each of these band-like bodies is configured in the form of a plain weave woven with warp and weft. For example, the second belt-like body 10b is formed by plain weaving with warp yarns 110b and weft yarns 110a as shown in a partially enlarged view in a circle picked up in a circular shape on the right side of FIG. 4A. Yes. The first belt-like body 10a is formed by plain weaving with warp yarns 100b and weft yarns 100a, as shown in a partially enlarged view in a circle picked up in the right circular shape in FIG. 4A. Yes. Although not shown, the third belt-like body 10c is formed by plain weaving with warps and wefts in the same manner as the first and second belt-like bodies. In the present invention, the heat shrinkage rate of the weft thread 100a constituting the first belt-like body 10a arranged so as to be located in the valley 3b of the bellows is arranged so as to be located in the peak 3a of the bellows. It is set to be larger than the thermal contraction rate of the weft yarn 110a constituting the second belt-like body 10b.
[0021]
This makes it possible to easily deform the bellows rubber preform into a shape along the shape of the bellows-like wall surface of the bellows by simply applying heat to the base fabric tubular body 10 'during the bellows manufacturing process. It is possible to fit in the outer shape and workability and yield can be significantly improved.
[0022]
In other words, in the present invention, the base fabric tubular body 10 ′ has a weft yarn in which the thermal shrinkage rate of the weft yarn 100 a arranged so as to be located in the hollow portion of the bellows valley portion 3 b is located at the top portion of the bellows peak portion 3 a. The heat shrinkage rate of 110a is taken into consideration and formed.
[0023]
Further, as a more preferable aspect, the third belt-like body 10c arranged so as to be positioned on the ring-shaped facing surface portions 2A and 2B of the bellows needs to be largely heat-shrinked similarly to the first belt-like body 10a. In addition, the heat shrinkage rate of the weft yarn is set to be larger than the heat shrinkage rate of the weft yarn of the second strip 10b. The relationship between the thermal contraction rate of the weft yarn of the third strip 10c and the thermal contraction rate of the weft yarn of the first strip 10a may be appropriately set in consideration of the bellows-like shape of the bellows. Further, the number of weft threads (number per inch width) in each belt-shaped body may be appropriately set in consideration of the heat shrink deformation of the base fabric tubular body 10 ′.
[0024]
Furthermore, the band-shaped bodies (for example, the first band-shaped body 10a and the third band-shaped body 10c) in which the thermal contraction of the base cloth cylindrical body 10 ′ is set to be large are the band-shaped bodies in which the heat shrinkage is set to be small ( For example, it is desirable to set the number of warp yarns to be driven (number per inch width) smaller than that of the second belt-like body 10b). This is to ensure that the heat shrinkage is greatly contracted. If the number of warp yarns is excessively large, the heat shrinkage of the weft yarn may be hindered by the warp yarn when the heat shrinkage of the weft yarn is increased. Paying particular attention to this point, it is necessary to set the number of warp threads to be driven. When the number of warp yarns to be driven is changed for each belt-like body, the warp yarns are woven so as to be discontinuous at the boundary portion of each belt state. Of course, when the number of warp yarns to be driven does not change, the yarns are woven so as to be continuous warp yarns.
[0025]
In addition, the heat shrinkage rate of the weft and the warp constituting the base fabric tubular body 10 ′ can be easily obtained by changing the longitudinal stretch rate at the time of forming the yarn and fixing the heat.
[0026]
As shown in FIG. 4B, the deformed base fabric 10 that is thermally contracted by heating has a form corresponding to the cross-sectional shape of the bellows wall surface (the shape including the peak and the valley). Therefore, the base fabric can be attached to the rubber preform in the process of manufacturing the bellows, which will be described later, extremely efficiently and reliably. The occurrence of defective products can also be reduced.
[0027]
The bellows-like wall surface portion 3 shown in FIG. 3 has a thickness in the range of, for example, about 0.15 to 1.8 mm, and the length of the bellows-like wall surface portion 3 (in FIG. 3, the facing surface portion 2A and the facing surface portion 2B). ), The number of ridges 3a (the number of steps), the shape, dimensions, and the like are not particularly limited, and can be appropriately set in consideration of the purpose of use of the bellows 1, required characteristics, and the like. For example, the cross-sectional shape of the peak portion 3a can be a semicircular shape, a triangular shape, or the like, and the shape and dimensions of the plurality of peak portions 3a may be the same, or consist of two or more types. May be.
[0028]
Such a bellows 1 includes a pair of ring-shaped facing surface portions 2A and 2B and a bellows-like wall surface portion 3 that face each other as described above, and has excellent responsiveness, and the facing surface portions 2A and 2B and the bellows-like wall surface portion. Excellent pressure resistance is imparted by the base fabric 10 embedded in 3.
[0029]
In addition, in order to maintain the form of the bellows 1 simply, you may make it attach a round and a reinforcement ring etc. to the trough part 3b along the circumferential direction.
[0030]
The rubber used in the bellows 1 of the present invention as described above may be a conventionally known synthetic rubber or natural rubber, and is not particularly limited. Synthetic rubbers usable in the present invention include, for example, acrylonitrile-butadiene rubber, styrene-butadiene rubber, butadiene rubber, isoprene rubber, propylene-butadiene rubber, acrylonitrile-isoprene rubber, chloroprene rubber, butyl rubber, ethylene-propylene rubber, acrylic Examples thereof include rubber, fluorine rubber, ether-thioether rubber, polysulfide rubber, urethane rubber, and silicon rubber. After adding additives such as a vulcanizing agent and a vulcanization accelerator as described later to such a rubber material as necessary, it is kneaded by a kneading machine, and the resulting rubber mixture is formed into a sheet shape beforehand by a roll. Then, the thickness is adjusted with a calendar to produce a sheet-like molded product (small piece), and then the bellows 1 can be produced by the production method of the present invention described later using this sheet-like molded product.
[0031]
The vulcanizing agent to be used can be appropriately selected according to the rubber used from sulfur, zinc oxide, magnesium oxide, aromatic nitro compound, organic peroxide and the like.
[0032]
Further, as vulcanization accelerators, thiazole compounds such as 2-mercaptobenzothiazole (MBT), sulfenamide compounds such as N-cyclohexyl-2-benzothiazole sulfenamide (CZ), 2-mercaptothiazoline and the like Thiazoline compounds, thiuram compounds such as tetramethylthiuram monosulfide (TT), tetraethylthiuram disulfide (TET), dithiocarbamate compounds such as dimethyldithiocarbamic acid, aldehyde amine compounds such as hexamethylenetetramine, guanidines such as diphenylguanidine Compounds, thiazole compounds such as N, N-diethylcarbamoyl-2-benzothiazyl sulfide, and the like can be used.
[0033]
Furthermore, you may contain anti-aging agents, organic fatty acids, such as stearic acid, and fillers, such as carbon black, as needed. Such an additive is preferably contained in an amount of 1 to 150 parts by weight per 100 parts by weight of rubber.
[0034]
As the base fabric 10 used in the bellows 1 of the present invention, a fabric made into plain weave using yarns such as polyamide (6 nylon, 66 nylon, etc.), aramid, polyester, cotton and the like is used. Various yarn shrinkage rates can be produced by the above-described stretching and heat setting techniques. In the present invention, at least two types of thermal shrinkage rates of weft yarn are used, and two or more types are different. A base cloth cylindrical body having a belt-like body having a heat shrinkage property is prepared.
[0035]
Production method <br/> then the bellows of the present invention, a method of manufacturing a bellows of the present invention will be described with reference to FIGS.
[0036]
(Preform molding process)
In the bellows manufacturing method of the present invention, first, in a preform molding step, a bellows rubber preform made of unvulcanized rubber is molded with a mold. FIG. 5 is a half-sectional view showing an example of a mold used in the preform molding process. In FIG. 5, a preform mold 21 is composed of a core 22, a middle mold 23, an upper mold 24, and a lower mold 25.
[0037]
The core 22 has a disk shape, includes an outer peripheral portion 22a having an inner peripheral surface shape of the bellows 1, and has a concave portion 22b for the bead portion 5 and a groove portion 22c for releasing excess rubber in a ring shape.
[0038]
The middle mold 23 has an inner peripheral part 23 a having the shape of the bellows-like wall surface part 3 of the bellows 1 and can be divided into two or more. In the illustrated example, the upper and lower end portions of the inner peripheral portion 23 a of the middle mold 23 coincide with the apexes of the upper and lower two crest portions constituting the bellows-like wall surface portion 3.
[0039]
The upper mold 24 and the lower mold 25 have a bellows between the outer peripheral portion 22a of the core 22 and the inner peripheral portion 23a of the middle mold 23 in a state where the core 22 and the middle mold 23 are engaged as illustrated. A gap (cavity) for forming the shaped wall portion 3 is formed. Further, the upper mold 24 and the lower mold 25 are formed with a recess 24a for forming a part of the bellows-like wall surface portion 3 and the opposing surface portions 2A and 2B, and a gap (cavity) between the upper die 24 and the lower die 25. Is formed.
[0040]
In such a preform mold 21, the core 22, the middle mold 23, the upper mold 24, and the lower mold 25 are formed in an engaged state as illustrated.
[0041]
The molding of the unvulcanized rubber bellows rubber preform using the preform mold 21 as described above is performed, for example, as shown in FIG. In a state where a plurality of unvulcanized rubber sheet-like molded articles (small pieces) are placed on the outer peripheral surface 22a of the core 22 and the upper surface of the core 22 and the concave portion 25a of the lower mold 25, Each mold member can be engaged and pressurized.
[0042]
At this time, it is necessary to set the temperature and pressure of the mold 21 within a range in which the unvulcanized rubber is not completely vulcanized. Further, pressurization may be performed in a range of about 3 to 90 seconds after several bumps, for example.
[0043]
FIG. 7 is a half-sectional view showing an example of a bellows rubber preform molded in the preform molding process using the mold 21 shown in FIG. 5, and corresponds to FIG.
[0044]
In FIG. 7, an unvulcanized rubber bellows rubber preform 11 is provided so that the opposing surface portions 12A and 12B of a pair of opposing ring-shaped flat plates and the outer peripheral edge portion of the opposing surface portion are connected to each other. The bellows-shaped wall surface part 13 which consists of the two peak parts 13a and the two trough parts 13b, and the bead part 15 (thread bead 15a) are provided in the inner peripheral part of opposing surface part 12A, 12B.
[0045]
In addition, when a burr | flash exists in the bellows rubber preform 11 taken out in the state engaged with the core 22 from the metal mold | die 21, this burr | flash is removed. Further, when the opposing surface portions 12A, 12B, etc. of the molded bellows rubber preform 11 have insufficient rubber thickness, an unvulcanized rubber sheet-like molding (small piece) as described above may be added to the corresponding portion. Good.
[0046]
(Second step)
In the second step of the bellows manufacturing method of the present invention, first, as shown in FIG. 6 (b), the opposing surface portions 12A and 12B of the bellows rubber preform 11 molded in the preform molding step described above. A cylindrical base cloth cylindrical body 10 ′ (for example, shown in FIG. 4A) prepared in advance is covered so as to cover the bellows-shaped wall surface portion 13. At this time, the base fabric tubular body 10 ′ receives heat (for example, a temperature of about 150 ° C.) accumulated in the bellows rubber preform 11 and thermally contracts. For example, FIG. ) And deformed in the same manner as the shape near the surface of the rubber preform as shown in FIG. In addition, when sufficient heat contraction cannot be performed only by the heat accumulated in the bellows rubber preform 11, it is necessary to forcibly heat the base fabric tubular body 10 ′ from the outside.
[0047]
Since such a base fabric 10 is designed in advance in anticipation of shrinkage deformation including a form corresponding to a cross-sectional shape (a shape including a peak portion and a valley portion) of the wall surface portion of the bellows, The base fabric can be attached very efficiently and reliably. That is, as shown in FIG. 6 (c), the base fabric 10 can be surely placed along the peak portion 13 a and the valley portion 13 b in the bellows-like wall surface portion 13 of the bellows rubber preform 11. Thereby, workability and product yield are greatly improved.
[0048]
Further, when the base fabric 10 is bonded to the facing surface portions 12A, 12B, etc. of the bellows rubber preform 11, it can be bonded using the above-mentioned small pieces of unvulcanized rubber material. After such application of the base fabric 10 is completed, the excess base fabric may be removed, and the base fabric 10 may be pressed against the bellows rubber preform 11 so that it does not wrinkle.
[0049]
Next, in the second step, the bellows rubber preform 11 around which the base fabric 10 is wound is vulcanized. In this example, the rubber preform is vulcanized after heat shrinkage of the base tubular body 10 ′, but considering the productivity, the heat shrinking and vulcanization operations should be performed almost simultaneously. Is desirable. As shown in FIG. 6 (d), the final molding die 41 is composed of the core 22, the middle die 43, the upper die 44, and the lower die 45. The core 22 is used in common with the core 22 constituting the preform molding die 21 used in the above-described preform molding step.
[0050]
The middle mold 43 has an inner peripheral part 43a having the shape of the bellows-like wall surface part 3 of the bellows 1, and can be divided into two or more. In the illustrated example, the upper and lower end portions of the inner peripheral portion 43 a of the middle mold 43 are respectively coincident with the apexes of the two upper and lower peaks constituting the bellows-like wall surface portion 3.
[0051]
Molding of the bellows 1 using such a final molding die 41 includes the core 22 having the bellows rubber preform 11 to which the base fabric 10 is attached as described above, the middle mold 43, and the upper Each member of the mold 44 and the lower mold 45 is engaged, pressurized and heated. The pressurization can be performed, for example, after bumping several times, and the temperature and time during vulcanization can be appropriately set according to the rubber material used.
[0052]
After the final molding using such a mold 41 is performed, the bellows 1 is taken out from the mold 41, and if there is a burr, the burr is removed to complete the manufacture of the bellows 1.
[0053]
In the bellows manufacturing method of the present invention described above, the core 22 of the mold 21 used in the preform molding process is shared with the core 22 of the mold 41 used in the second process. The invention is not limited to this. For example, the base fabric 10 may be mounted after the bellows rubber preform 11 molded in the preform molding process is mounted on the core dedicated to the mold 41.
[0054]
In this embodiment, a three-stage bellows (for example, used for vibration isolation) that requires pressure resistance has been described as an example. However, the present invention is not limited to this and includes several stages to several tens of stages. Of course, it can also be applied to the manufacture of bellows. As an example of the bellows consisting of several tens of steps, there is a long protective bellows used to cover the elastic member.
[0055]
【The invention's effect】
As described above in detail, according to the bellows manufacturing method of the present invention, since the base cloth cylindrical body including the belt-shaped body having two or more different heat shrinkage rate properties is used, the base cloth cylinder is used in the manufacturing process. By simply applying heat to the body 10 ', it can be easily deformed into a shape that conforms to the shape of the bellows-like wall surface of the bellows, and can be perfectly adapted to the outer shape of the bellows rubber preform. There are few occurrences of wrinkles, rubber scraping, and rubber scratches associated with the attachment of the cloth, and the product yield and work efficiency can be improved.
[Brief description of the drawings]
FIG. 1 is a perspective view showing an embodiment of a bellows of the present invention.
FIG. 2 is a plan view of the bellows shown in FIG.
FIG. 3 is a half-sectional view taken along the line AA in FIG. 2;
4 (a) is a preferred schematic perspective view of the base cloth cylindrical body before being attached to the bellows 1, and FIG. 4 (b) is a diagram showing a predetermined location of the base cloth cylindrical body after being attached. It is a schematic perspective view of the state which changed into the form similar to the bellows shape of bellows 1 by carrying out predetermined heat contraction.
FIG. 5 is a half-sectional view showing an example of a mold used in a preform molding step of the bellows manufacturing method of the present invention.
6A and 6B are diagrams illustrating a method for manufacturing a bellows according to the present invention, in which FIG. 6A is a half-sectional view illustrating a state in which a bellows rubber preform is molded in a preform molding process, and FIG. It is a half piece sectional view showing the situation where a base fabric is attached to a foam, (c) is a half piece sectional view showing a bellows rubber preform coated with a base fabric, and (d) is a half piece cross section showing a vulcanization molding process. FIG.
7 is a view showing a bellows rubber preform formed by the preform forming step of the bellows manufacturing method of the present invention, and is a view corresponding to FIG. 3. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Bellows 2A, 2B ... Opposite surface part 3 ... Bellows-like wall surface part 3a ... Mountain part 3b ... Valley part 4 ... Opening part 5 ... Bead part 10 ... Base cloth 10 '... Base cloth cylindrical body 10a, 10b, 10c ... Belt-like body 11 ... Bellows rubber preform 21, 31, 41 ... Mold 22, 32 ... Core 23, 33, 43 ... Middle die 24, 34, 44 ... Upper die 25, 35, 45 ... Lower die 50, 60 ... Base Cloth molding mold

Claims (6)

A cylindrical base fabric tubular body woven with weft yarns constituting the bellows circumferential direction and warp yarns orthogonal to the weft yarns, and the weft yarn has a thermal shrinkage of at least two or more types, A base fabric preparation step of preparing a base fabric cylindrical body including a belt-like body having two or more different heat shrinkage properties,
A bellows-like wall surface having a pair of ring-shaped facing surface portions arranged so as to face each other, and two or more peak portions and one or more valley portions provided so as to connect the outer peripheral edge portions of the facing surface portions to each other A preform molding step of molding a bellows rubber preform of unvulcanized rubber with a mold,
The base cloth cylindrical body is disposed on the rubber preform formed by the preform molding process so that the base cloth cylindrical body is covered with heat, and the base cloth cylindrical body is made of the rubber preform. while embedded in the vicinity of the surface as a base fabric, a deposition-vulcanizing step of vulcanizing the rubber preform seen including,
The base fabric tubular body is set so that the thermal contraction rate of the weft arranged so as to be located in the recess of the trough is larger than the thermal contraction rate of the weft located in the top of the peak. A method for producing a bellows, comprising: A cylindrical base fabric tubular body woven with weft yarns constituting the bellows circumferential direction and warp yarns orthogonal to the weft yarns, and the weft yarn has a thermal shrinkage of at least two or more types, A base fabric preparation step of preparing a base fabric cylindrical body including a belt-like body having two or more different heat shrinkage properties,
A bellows-like wall surface having a pair of ring-shaped facing surface portions arranged so as to face each other, and two or more peak portions and one or more valley portions provided so as to connect the outer peripheral edge portions of the facing surface portions to each other A preform molding step of molding a bellows rubber preform of unvulcanized rubber with a mold,
The base cloth cylindrical body is disposed on the rubber preform formed by the preform molding process so that the base cloth cylindrical body is covered with heat, and the base cloth cylindrical body is made of the rubber preform. while embedded in the vicinity of the surface as a base fabric, a deposition-vulcanizing step of vulcanizing the rubber preform seen including,
The base cloth cylindrical body includes a first belt-like body arranged so as to be located in the vicinity of the depression of the valley part, and a second belt-like body arranged so as to be located in the vicinity of the top part of the mountain part. And a method for producing a bellows, characterized in that the heat shrinkage rate of the weft yarn of the first belt-like body is set to be larger than the heat shrinkage rate of the weft yarn of the second belt-like body . The base cloth tubular body includes a third belt-like body disposed so as to be positioned on the ring-shaped facing surface portion, and the thermal contraction rate of the weft yarn of the third belt-like body is the second belt-like body. The manufacturing method of the bellows of Claim 2 set so that it may become larger than the thermal contraction rate of the weft of a body. The method for producing a bellows according to any one of claims 1 to 3 , wherein the rubber preform is vulcanized after heat shrinkage of the base cloth cylindrical body. The method for producing a bellows according to any one of claims 1 to 3 , wherein the rubber preform is vulcanized simultaneously with the thermal contraction of the base cloth cylindrical body. The strip of heat-shrinkage of the weft yarns of the base fabric tubular body is set large, as compared to strip the thermal shrinkage rate is set small, claim 2 implantation number of warp yarns is set smaller The manufacturing method of the bellows in any one of Claim 5 thru | or 5 .

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