JP4034880B2 - 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 opposed to a base fabric molding step in which a belt-shaped base fabric is preformed in advance according to the cross-sectional shape of the wall surface of the bellows. A pair of ring-shaped opposing surface portions arranged, 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 opposing surface portions to each other; A preform molding process for molding an unvulcanized rubber bellows rubber preform with a mold, and the preformed belt-shaped base fabric on the wall surface of the bellows of the bellows rubber preform formed by the preform molding process. A step of winding and adhering, and a vulcanization molding step of pressing the attached base fabric into a bellows preform of unvulcanized rubber with a mold and vulcanizing the unvulcanized rubber. , The base fabric molder In the belt-shaped base fabric to be processed, the thermal contraction rate of the weft constituting the base fabric is changed according to the cross-sectional shape of the wall surface portion of the bellows, and the thermal contraction of the weft located in the valley portion The rate is configured to be set to be larger than the thermal shrinkage rate of the weft located at the peak portion .
[0008]
Moreover, as a more preferable aspect of the present invention, the base fabric forming step is performed by press-molding the base fabric with a base fabric forming mold having a cross-sectional shape of the wall surface portion of the bellows.
[0009]
As a more preferred embodiment of the present invention, the belt-shaped base fabric to be processed in the base fabric forming step is configured to be a plain-woven belt-shaped base fabric woven with warp and weft.
[0012]
Further, as a more preferable aspect of the present invention, the base fabric forming step is configured such that a slight curl corresponding to the curvature of the winding of the base fabric is formed by utilizing the molding shrinkage of the base fabric. .
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0014]
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.
[0015]
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.
[0016]
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).
[0017]
The preferred base fabric 10 used in the present invention is exemplified by a plain weave belt-like base fabric woven with warp and weft, which is a cross-sectional shape of a bellows wall surface (a shape having peaks and valleys). ) In advance with a mold or the like.
[0018]
An example of a suitable mold used for this preforming is shown in FIG. 4, and the shape of the base fabric 10 after molding is shown in FIG. FIG. 4 schematically shows a cross section of a suitable mold structure used for preforming, and this molding mold 50 is a female mold having a molding recess 51a corresponding to the sectional shape of the wall surface of the bellows. 51 and a male die 55 having a molding convex portion 55a corresponding to the cross-sectional shape of the wall surface of the bellows, and the base fabric 10 is press-molded in the illustrated state. The molding die 50 is configured to have a mold length corresponding to the length of the strip in the depth direction of the paper surface of FIG. 4 corresponding to the length of the strip-shaped base fabric to be molded. When the base fabric 10 is actually molded, a band-shaped base fabric before molding is set between the opened female die 51 and the male die 55, and then, as shown in FIG. When the mold 55 is clamped, the base fabric 10 is molded into a predetermined shape. In order to make the molding easy and reliable, it is usually desirable to heat the mold to about 130 to 180 ° C. A perspective view showing an example of the base fabric 10 molded in this way is shown in FIG.
[0019]
As shown in FIG. 5, the molded base fabric 10 has a form corresponding to the cross-sectional shape of the wall surface of the bellows (a shape including a peak and a valley), and thus in the bellows manufacturing process described later. Winding of the base fabric around the rubber preform can be performed very efficiently and reliably. In addition, it is also a preferable aspect to intentionally provide a slight curl (in the direction of the arrow (α) in FIG. 5) corresponding to the curvature of the winding of the base fabric by utilizing the molding shrinkage of the base fabric 10. .
[0020]
An example of a technique for continuously forming the base fabric 10 is shown in FIGS. Fig.6 (a) is a side view which shows the state of base fabric shaping | molding, FIG.6 (b) is a front view of Fig.6 (a). As shown in FIG. 6 (a), the base fabric 10a before being continuously conveyed is passed through the molding die 60, whereby the base fabric 10 having a predetermined shape (for example, shown in FIG. 5). To be molded. That is, the molding die 60 is composed of a disk-shaped rotating male die 65 having a predetermined convex portion 65a and a female die 61 having a fixed and predetermined concave portion 61a, and is a base before molding that is continuously conveyed. When the cloth 10 a passes through the mold 60, the cloth 10 a is sandwiched and formed between the female mold 61 and the rotating male mold 65, and is taken out as a molded base cloth 10. In order to make the molding easy and reliable, it is usually desirable to heat the mold to about 130 to 180 ° C. Such a molded article is usually once wound into a roll shape, then drawn out to an appropriate length for use and cut, and used as a belt-like base fabric.
[0021]
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.
[0022]
Such a bellows 1 includes a pair of ring-shaped facing surface portions 2A and 2B and a bellows-like wall surface portion 3 which 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.
[0023]
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.
[0024]
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. Examples of the synthetic rubber that can be used in the present invention include acrylonitrile-butadiene rubber, styrene-butadiene rubber, butadiene rubber, isoprene rubber, propylene-butadiene rubber, acrylonitrile-isoprene rubber, chloroprene rubber, butyl rubber, ethylene-propylene rubber, and 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.
[0025]
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.
[0026]
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.
[0027]
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.
[0028]
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. Since the base fabric 10 is preliminarily molded before being incorporated into the bellows 1, the yarn generally has a substantially constant heat shrinkage rate, in particular, the weft yarn constituting the base fabric has a substantially constant heat shrinkage rate. Some are used.
[0029]
Moreover, in order to improve the workability of the preforming, yarns having different heat shrinkage rates may be appropriately arranged and used. For example, the heat shrinkage rate of the weft yarn that constitutes the base fabric is changed according to the cross-sectional shape of the wall surface portion of the bellows, and the heat shrinkage rate of the weft yarn located at the valley portion is the heat shrinkage rate of the weft yarn located at the mountain portion. A preferable example is one that is set to be larger than the shrinkage rate.
[0030]
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.
[0031]
(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. 7 is a half-sectional view showing an example of a mold used in the preform molding step. In FIG. 7, a preform mold 21 is composed of a core 22, a middle mold 23, an upper mold 24, and a lower mold 25.
[0032]
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.
[0033]
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.
[0034]
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.
[0035]
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.
[0036]
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.
[0037]
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.
[0038]
FIG. 9 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. 7, and corresponds to FIG.
[0039]
In FIG. 9, an unvulcanized rubber bellows rubber preform 11 is provided so that the opposing surface portions 12 </ b> A and 12 </ b> B 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.
[0040]
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.
[0041]
(Second step)
In the second step of the bellows manufacturing method of the present invention, first, as shown in FIG. 8 (b), the opposing surface portions 12A and 12B of the bellows rubber preform 11 molded in the preform molding step described above. Then, the preformed belt-like base fabric 10 (for example, shown in FIG. 5) is wound and attached so as to cover the bellows-like wall portion 13.
[0042]
In FIG. 8 (b), the base fabric preformed as shown in FIG. 5 on the bellows rubber preform 11 taken out from the mold 21 while being attached to the core 22 in the preform molding step. 10 is attached. The base fabric 10 is attached, for example, by winding the side surface of the bellows rubber preform 11 around.
[0043]
Since this base fabric 10 is preformed in advance so as to have a form corresponding to the cross-sectional shape (shape having a crest and a trough) of the wall surface of the bellows as shown in FIG. Winding the base fabric around the foam can be performed very efficiently and reliably. That is, as shown in FIG. 8 (c), the base fabric 10 can be surely placed along the peak portion 13 a and the valley portion 13 b of the bellows-like wall surface portion 13 of the bellows rubber preform 11. Thereby, workability and product yield are greatly improved.
[0044]
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.
[0045]
Next, in the second step, the bellows rubber preform 11 around which the base fabric 10 is wound is vulcanized. As shown in FIG. 8 (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.
[0046]
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.
[0047]
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.
[0048]
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.
[0049]
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.
[0050]
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.
[0051]
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.
[0052]
【The invention's effect】
As described above in detail, according to the present invention, a belt-shaped base fabric preformed in advance according to the cross-sectional shape of the wall surface portion of the bellows is used, and this is wound around the wall surface portion of the bellows of the rubber preform. Since it is configured to adhere, there are few occurrences of wrinkles, rubber scraping and rubber scratching due to the mounting of the base fabric, 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;
FIG. 4 schematically shows a cross section of a suitable mold structure used for preforming a base fabric in the present embodiment.
FIG. 5 is a perspective view of a base fabric after preforming.
6A is a side view showing a state in which a base fabric is continuously formed, and FIG. 6B is a front view of FIG. 6A.
FIG. 7 is a half-sectional view showing an example of a mold used in the preform molding step of the bellows manufacturing method of the present invention.
8A and 8B are diagrams for explaining a method for producing a bellows according to the present invention, wherein FIG. 8A is a half-sectional view showing a situation 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.
FIG. 9 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;
[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 11 ... Bellows rubber preform 21, 31, 41 ... Mold 22, 32 ... Cores 23, 33, 43 ... Middle dies 24, 34, 44 ... Upper dies 25, 35, 45 ... Lower dies 50, 60 ... Base fabric molding dies

Claims (4)

A base fabric molding step in which a belt-shaped base fabric is preformed in advance according to the cross-sectional shape of the wall surface of the bellows;
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,
Wrapping and attaching the preformed belt-shaped base fabric around the wall surface of the bellows of the bellows rubber preform formed by the preform molding step;
A vulcanization molding step of vulcanizing the unvulcanized rubber while pushing the adhered base fabric into a bellows preform of unvulcanized rubber with a mold ,
In the base fabric molding step, the belt-shaped base fabric to be processed has a heat shrinkage rate of the weft constituting the base fabric changed according to the cross-sectional shape of the wall surface portion of the bellows, and is located in the valley portion. A method for producing a bellows, characterized in that the heat shrinkage rate of the weft yarn to be set is set to be larger than the heat shrinkage rate of the weft yarn located at the peak portion .   The said base fabric shaping | molding process is a manufacturing method of the bellows of Claim 1 performed by press-molding a base fabric with the base fabric shaping die which has the cross-sectional shape of the wall surface part of a bellows.   The method for producing a bellows according to claim 2, wherein the belt-like base fabric to be processed in the base fabric forming step is a plain-woven belt-like base fabric woven with warp and weft. The bellows according to any one of claims 1 to 3 , wherein, in the base fabric forming step, a slight curl is formed in accordance with a curve of the winding of the base fabric by utilizing molding shrinkage of the base fabric. Production method.

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