Washer with elastic water-swollen rubber

Abstract: A washer (10) with an elastic water-swollen rubber has an annular washer (11), and an annular packing member (12) aligned and overlapped with the annular washer (11) and partly fitted in a perforation formed in the annular washer (11). The annular washer (11) is subjected to rust-proof treatment on its surface excepting a large part (11A) of its contacting surface relative to the annular packing member (12). The annular packing member (12) is formed of an elastic water-swollen rubber. The annular washer (11) and the annular packing member (12) are fixed together by vulcanized adhesive.

Description: BACKGROUND OF THE INVENTION [Field of the Invention] This invention relates to a washer with an elastic water-swollen rubber which is used as a water sealing device when two segments are connected by a bolt at junctions thereof, or in similar cases. [Description of the Prior Art] Concrete segments are widely used for constructing architecture such as tunnel, etc. These concrete segments are gradually assembled in such a manner as being connected by a bolt at junctions and are served as component elements for constructing such architecture as tunnel, etc. Water sealing devices are often used together with a bolt in order to water seal the junctions when the concrete segments are connected by a bolt. As one example of a water sealing device a washer having the features of the first part of claim 1 is known from Japanese Utility Model Early Laid-open Publication No. Sho 62-133019. This water sealing packing member is used for water sealing the surrounding area of the bolt, and comprises a disc washer and an annular packing member axially aligned with each other and integrally formed by fitting the packing member into the washer or fixing them by adhesive. The Japanese Publication also discloses that the annular packing member is preferably formed of an elastic water-swollen composition. However, where the conventional water sealing packing member is used as a water sealing device of concrete segments, there was such problems as that the washer used together with the water sealing packing member is suffered from serious corrosion as the passage of years because the circumstances under which it is used, are usually bad. Moreover, there were such problems as that the water sealing function is not sufficient because the integral connection between the washer and the water sealing packing member is not necessarily perfect. SUMMARY OF THE INVENTION The object of the present invention is to provide a washer with an elastic water-swollen rubber which does not suffer corrosion even if it is used under bad circumstances and which is capable of safely tightening the junctions of a washer and a packing member to exhibit a reliable water sealing function. This object is solved by a washer with an elastic water-swollen rubber having the features of claim 1. According to the present invention, when the segments are tightened at their junctions using a bolt having the washer with an elastic water-swollen rubber, a tiny gap, which is usually formed between the bolt and the junctions, can be water sealed by the washer with an elastic water-swollen rubber. Furthermore, even when it is used under bad circumstances, it can maintain a sufficiently reliable water. sealing function without being suffered from corrosion. In addition, since the annular packing member is swollen by water to fill up the tiny gap formed around the bolt tightening portion, the bolt tightening portion can be more perfectly water sealed. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a sectional view showing one embodiment of a washer with an elastic water-swollen rubber according to the present invention; Fig. 2 is a sectional view showing a part of the washer with an elastic water-swollen rubber shown in Fig. 1, on an enlarged scale; and Fig. 3 is a sectional view of an important portion showing two concrete segments connected together by a bolt incorporated with the washer with an elastic water-swollen rubber shown in Fig. 1. DETAILED DESCRIPTION OF THE EMBODIMENT The present invention will be described hereinafter with reference to Figs. 1 through 3. A washer 10 with an elastic water-swollen rubber of this embodiment, as shown in Fig. 1, comprises an annular washer 11 and an annular packing member 12 axially aligned and overlapped with the washer 11 and partly fitted in a perforation formed in the washer 11. The annular packing member 12, as shown in Fig. 1, is formed of an elastic water swollen rubber, and a part of the member 12 has a cylindrical thin wall configuration. More specifically, this annular packing member 12 comprises a cylindrical thin wall fit-in portion 12A to be fitted into the aperture of the washer 11 and contacted at its outer peripheral surface with the inner peripheral surface of the washer 11, and a cylindrical thick wall portion 12B continuously formed next to the fit-in portion 12A and overlapped at its inner peripheral edge portion with the washer 11. Both the portions 12A and 12B define a through-hole or aperture having an inner peripheral surface to be contacted with an outer peripheral surface of a bolt. The annular washer 11 is subjected to rust-proof treatment on a surface thereof excepting a large part 11A of its contacting surface relative to the annular packing member 12. In other words, as shown in Fig. 2, the annular washer 11, which is aligned and overlapped with the annular packing member 12, is provided with a rust-proof treatment portion 11B having a rust-proof treatment on the area starting from its outer surface to a slightly inner side of its contacting surface relative to the annular packing member 12, i.e., in the vicinity of the distal end of the fit-in portion 12A as well as the outer peripheral portion of the overlapped portion 12B. A large part of the remaining contacting surface forms a non rust-proof treatment portion 11A (the portion not hatched in Fig. 2). The annular washer 11 and the annular packing member 12 are fixed together at contacting surfaces thereof by vulcanized adhesive and thus integrally formed. The washer 10 with an elastic water-swollen rubber constituted by integrally fixing together the annular washer 11 and the annular packing member 12 in the manner as mentioned above, has, as shown in Fig. 3, an inner diameter matching with the outer diameter of a bolt 20 to be used. Accordingly, when the bolt 20 is inserted into the washer 10 with an elastic water-swollen rubber, the entire inner peripheral surface of the annular packing member 12 is readily contacted with the outer peripheral surface of the bolt 20. The annular washer 11 of this washer 10 with an elastic water-swollen rubber is subjected to rust-proof treatment as mentioned above. This rust-proof treatment is made by teflon coating, or coating of general rust-proof coating material. In view of rust-proof effect, however, the Teflon coating is preferable. The elastic water-swollen rubber forming the annular packing member 12 of this washer 10 with an elastic water-swollen rubber is not particularly limited as long as the rubber has the properties as being swollen when it absorbs water. Acceptable elastic water-swollen rubbers include, for example, a mixture of such known water-absorbing polymers as elastic water-swollen polyurethane resin or starch/acrylic acid graft copolymer and crosslinked poly (sodium acrylate) mixed with rubbers such as natural rubbers, synthetic rubbers and reclaimed rubbers. Among them, a flexible substance including elastic water-swollen polyurethane resin is preferable. It is preferable that the composition of the flexible substance may be controlled in such a manner as to give a water-swelling ratio of the resulting molded article of 10 to 350 %, still preferably 40 to 250 %. The flexible substance including water-swollen polyurethane resin as described above may be obtained by kneading one or more polyether polyols of the following general formula together with urethane polymer(s) having terminal isocyanate groups obtained from polyisocyanate, a crosslinking agent and the rubber as defined above followed by curing. R [ ( O R' ) n O H ] p wherein R represents a polyhydric alcohol residue; (OR') represents a polyoxyalkylene chain comprising oxyalkylene groups each having an oxyethylene group and an alkylene group carrying three or four carbon atoms, provided that the content of the oxyethylene groups amounts to 20 to 100% of the total molecular weight; n is a number corresponding to the degree of polymerization of the oxyalkylene groups and giving a hydroxyl group equivalent of 200 to 2500; and p is a number of 2 to 8, preferably 2 to 4; Said polyether plyols may be obtained by adding alkylene oxide(s) to said polyhydric alcohols in such a manner as to give the desired molecular weight. Either random or block addition may be employed therefor. Examples of said polyhydric alcohol include dihydric alcohols such as ethylene glycol and propylene glycol; trihydric alcohols such as glycerol and trimethylolpropane; tetrahydric alcohols such as erythritol and pentaerythritol; pentahydric alcohols such as arabitol and xylitol; and hexahydric alcohols such as sorbitol and mannitol. When the content of the oxyethylene groups is less than 20 %, the resulting material is unsatisfactory as a waterstop material. The urethane polymer has terminal isocyanate groups. Any polyisocyanates may be employed. The content of the terminal isocyanate groups may be 1 to 12 %, preferably 2 to 7 %. Examples of said crosslinking agent include polyols and polyamines each carrying two to six active hydrogen atoms per molecule and has an average molecular weight per active hydrogen atom of 30 to 15000, for example, low-molecular weight polyols, addition polymers of low-molecular weight polyols and alkylene oxides, low-molecular weight polyamines, and addition polymers of low-molecular weight polyamines and alkylene oxides, as well as mixtures thereof. It is preferable that the flexible substance as described above contains 20 to 800 parts of the water-swollen polyurethane resin per 100 parts of the rubber. Other examples of preferable flexible substances are those obtained by further adding hydraulic material(s) to a composition comprising said water-swollen polyurethane resin and rubber. Examples of available hydraulic materials include Portland cement, blast furnace cement, colloidal cement and gypsum. It is preferable to employ a curing accelerator for cement comprising calcium aluminate simultaneously therewith. A flexibile substance comprising such a hydraulic material has an advantage that it shows little shrinkage when dried. It is preferable that the hydraulic material is blended in an amount of 20 to 30 parts per 100 parts of the mixture of the water-swollen polyurethane and rubber. The above flexible substance may further contain appropriate water-absorbing material(s). Examples of the water-absorbing materials include those mainly comprising an α,β-unsaturated compound, which carries one or more carboxyl groups or those capable of being derived thereto such as carboxyl, carboxylate, carboxylic limide, carboxylic amide or carboxylic anhydride groups per molecule, and optionally polymerized with other α,β-unsaturated compound(s) and/or modified with isocyanate(s). Examples of such a water-absorbing resin include conventional water-absorbing polymers such as starch/acrylic acid graft copolymer, a salt of styrene/maleic anhydride copolymer, crosslinked poly(sodium acrylate), vinyl ester/ethylenically unsaturated carboxylic acids, and saponified products of derivatives thereof. The flexible substance may be further vulcanized with the use of a crosslinking agent such as sulfur. The annular washer 11 and the annular packing member 12 in this washer 10 with an elastic water-swollen rubber are fixed together as follows. After a vulcanized adhesive is uniformly applied to the contacting surface of the annular washer 11 relative to the annular packing member 12 using a brush, a sprayer or the like, the solvent of vulcanized adhesive is evaporated to dry the vulcanized adhesive. Then, the annular washer 11 and the annular packing member 12 are fitted together and affixed by heated vulcanized adhesive or otherwise, the annular packing member 12 is fixed to the annular washer 11 by vulcanized adhesive at the same time the annular packing member 12 is press molded. A preferable example of the vulcanized adhesive is one belonging to the series of chlorinated rubbers. Next, one mode for connecting two concrete segments using the washer with an elastic water-swollen rubber will be described with reference to Fig. 3. Each of the concrete segments 30 to be connected by the washer 10 with an elastic water-swollen rubber is provided with a bolt hole 30A formed in its junction as shown in Fig. 3. The bolt hole 30A is provided with a tapered portion 30B formed on one side of its opening. The overlapped portion 12B of the annular packing member 12 in the washer 10 with an elastic water-swollen rubber is fitted into this tapered portion 30B. To connect the concrete segments 30, the concrete segments 30 are first overlapped with each other in such a manner as that the bolt holes 30A are aligned with each other with the tapered portions 30B placed on the outer surface side. Thereafter, the bolt 20 having the washer 10 with an elastic water-swollen rubber mounted thereon beforehand is inserted into the concrete segments 30. Then, the overlapped portion 12B of the annular packing member 12 is fitted the tapered portion 30B, and the distal end of the bolt 20 is projected from the concrete segment 30. Another washer 10 with an elastic water-swollen rubber is mounted from the projecting distal end of the bolt 20, and the overlapped portion 12B of the annular packing member 12 is fitted into the tapered portion 30B of the bolt hole 30A. Thereafter, a nut 40 is threadedly engaged with the distal end of the bolt 20 and tightened to connect the concrete segments 30 together. In this way, when two concrete segments 30 are connected together, the annular packing member 12 is compression deformed by the tightening force incurred at that time and intimately attached to the bolt holes 30A and the tapered portions 30B of the concrete segments 30 to seal the surrounding area of the bolt 20. As a result, the bolt tightening portions of the connected concrete segments 30 are water sealed. In a state where the concrete segments 30 are connected together as shown in Fig. 3, when rain water, etc. attempts to enter through the bolt tightening portions in the concrete segments 30, this water is impregnated into the annular packing member 12 to swell the annular packing member 12. As a result, the bolt tightening portions can be water sealed more safely. Further, since the rust-proof treatment portion 11B reaches the contacting surface of the annular packing member 12, the non rust-treatment portion 11A is never exposed to bad using circumstances. As a result, the annular washer 11 can be surely prevented from getting into corrosion. The present invention is not limited to the above embodiment as long as the washer with an elastic water-swollen rubber comprises an annular washer and an annular packing member aligned and overlapped with the annular washer and partly fitted into an aperture formed in the annular washer, the annular washer being subjected to rust-proof treatment at its surface excluding a large part of its contacting surface relative to the annular packing member, the annular washer and the annular packing member being fixed together by vulcanized adhesive. Particularly, the annular packing member can be formed into various configurations as long as it is designed such that a part of the annular packing member is fitted into the aperture of the annular washer and disposed between the bolt and the junction. The washer with an elastic water-swollen rubber according to the present invention does not get into corrosion even when it is used under bad circumstances, and the washer and the packing member are perfectly integrally formed to surely tighten the junctions. As a result, a highly satisfactory water sealing effect can be obtained.

Claims: A washer with an elastic water-swollen rubber comprising an annular washer (11), and an annular packing member (12) aligned and overlapped with said annular washer (11) and partly fitted in a perforation formed in said annular washer (11), said annular packing member (12) being formed of an elastic water-swollen rubber, and said annular washer (11) and said annular packing member (12) being fixed together, characterized in that said annular washer (11) is provided with a rust-proof treatment surface portion (11B) thereof excepting a large part (11A) of its contacting surface relative to said annular packing member (12); and the annular washer (11) and the annular packing member (12) are fixed together by vulcanized adhesive. A washer with an elastic water-swollen rubber as claimed in claim 1, characterized in that an inner diameter of said washer with an elastic water-swollen rubber matches the outer diameter of a bolt (20) to be used. A washer with an elastic water-swollen rubber as claimed in claim 1, characterized in that said elastic water-swollen rubber is a flexible substance including elastic water-swollen polyurethane resin. A washer with an elastic water-swollen rubber as claimed in claim 3, characterized in that the composition of said flexible substance is controlled in such a manner as to give a water-swelling ratio of the resulting molded article of 10 to 350 %.

Inventors: FUKUSHIMA TAKUO C O ASAHI DENK, ICHIZUKA ISAMU C O ASAHI DENKA, INOUE HIROSHI C O ASAHI DENKA, UENO TOKIO C O ASAHI DENKA KOG, FUKUSHIMA, TAKUO, C/O ASAHI DENKA KOGYO K. K., ICHIZUKA, ISAMU, C/O ASAHI DENKA KOGYO K. K., INOUE, HIROSHI, C/O ASAHI DENKA KOGYO K. K., UENO, TOKIO, C/O ASAHI DENKA KOGYO K. K.
Applicants: ASAHI DENKA KOGYO KK, ASAHI DENKA KOGYO KABUSHIKI KAISHA
Application year: 1991
Main classification: E21D11
IPC codes: F16B43, F16J15, E21D11