Male fastening tool

A male fastening tool body includes a body part, a flange part which has a seat surface, an annular concave part formed between the body part and the seat surface, and a resinous ring-shaped member disposed at the annular concave part. The annular concave part has an annular concave peripheral edge portion. The resinous ring-shaped member has an annular projected part which fills almost the entire annular concave part and a lower surface of which is projected downward beyond the seat surface and an annular peripheral part, having a tapered bottom surface or a curved bottom surface, which is formed between the annular projected part and the outer edge of the resinous ring-shaped member and becomes gradually thinner, with an outer edge of the resinous ring-shaped member being located at an outer edge of the annular concave peripheral edge portion or slightly toward the side of the body part.

BACKGROUND OF THE INVENTION

The present invention relates to a male fastening tool to be used to fasten a member to a portion where a sealing property is demanded.

Various members are fixed to portions respectively where they are to be fastened by using a fastening tool such as a bolt, a nut, a plug, and the like. In dependence on a portion, it is necessary to fasten a member with preferable sealing performance against leak of water and oil.

To fasten the member to the portion where preferable sealing performance is demanded, a sealing ring such as a rubber ring is used in combination with a metal washer ring at the portion where the preferable sealing performance is demanded. But the use of such rings may thicken the portion to which the member should be fastened with preferable sealing performance and may cause defective sealing to occur owing to deviation of the sealing ring.

To overcome this problem, many fastening tools (for example, bolt) having sealing performance have been proposed. In the bolt disclosed in JPB1990-50328 2-50328, patent document 1), the annular groove part having the approximately semicircular cross section is concavely formed on the peripheral surface of the neck part disposed on the lower surface of the bolt head. There is provided the packing material having the integrally formed annular tongue edge part having the approximately triangular cross section. The annular tongue edge part can be filled in the filling part formed from the lower surface of the annular packing member fitted in the annular groove part to the open edge of the bolt hole. A member is fixed to the bolt hole by means of the annular groove part in cooperation with the packing member. Inside the annular groove part, there is provided the neck part-sealing part having the annular projected convexity projected inward or the annular concavity concaved outward.

The present applicant proposed the bolt as disclosed in WO2008/10523 (patent document 2). The bolt 1 of the patent document 2 has the bolt body 2 including the screw part 5, the head part 6 formed at the upper end of the screw part 5, and the flange part 7 formed at the lower end of the head part 6; and the unconductive resinous ring-shaped member 3 covering the peripheral portion of the flange part 7. The flange part 7 has the disk-shaped flange body portion 71 and the seat surface-forming portion 72 having the seat surface 73 which is extended toward the screw part from the lower surface of the flange body portion 71, has a smaller diameter than that of the flange body portion 71, and is pressed against the portion where the bolt is to be mounted. The resinous ring-shaped member 3 has the edge part 31 which is located at the position nearer to the lower end of the screw part 5 than the seat surface 73 and outward from the flange body portion 7 and the annular skirt part 32 whose diameter gradually increases to the edge part 31. The annular skirt part 32 deforms when the bolt is mounted on the portion where the bolt is to be mounted, does not restrain the seat surface 73 from being pressed against the portion where the bolt is to be mounted, and forms the annular liquid-tight sealing portion for the portion where the bolt is to be mounted. The bolt of WO2008/10523 invention is especially effective for preventing the occurrence of electrolytic corrosion.

The bolt disclosed in the patent document 1 has an effect to some extent, but is demanded to have higher liquid-tight sealing performance. The bolt disclosed in the patent document 2 has sufficient sealing performance, but the unconductive resinous ring-shaped member projects beyond the bolt body. Thus the entire head part is large and portions where the bolt can be used are limited to specific portions.

Therefore it is an object of the present invention to provide a male fastening tool which is not large and is capable of imparting sufficient liquid-tight sealing performance to a portion to which a member is to be fastened.

SUMMARY OF THE INVENTION

The above-described object is achieved by a male fastening tool.

A male fastening tool comprises a male fastening tool body essentially including a body part having a male screw portion formed thereon, a flange part which is formed on an upper end of said body part and has a seat surface, to be pressed against a portion on which said male fastening tool is to be mounted, which is disposed on a periphery of a lower surface thereof, and an annular concave part formed between said body part and said seat surface of said flange part; and a resinous ring-shaped member disposed at said annular concave part of said male fastening tool body, wherein said annular concave part of said male fastening tool body further comprises an annular concave peripheral edge portion which becomes gradually shallower toward said seat surface; and

an outer edge of said resinous ring-shaped member is located at an outer edge of said annular concave peripheral edge portion of said annular concave part or slightly toward a side of said body part with respect to said outer edge of said annular concave peripheral edge portion; said resinous ring-shaped member has an annular projected part which fills almost an entirety of said annular concave part and a lower surface of which is projected downward beyond said seat surface and an annular peripheral part, having a tapered bottom surface or a curved bottom surface, which is formed between said annular projected part and said outer edge of said resinous ring-shaped member and becomes gradually thinner; wherein said resinous ring-shaped member deforms when said male fastening tool is mounted on said portion on which said male fastening tool is to be mounted, does not restrain said seat surface from being pressed against said portion on which said male fastening tool is to be mounted, and forms an annular liquid-tight sealing portion for said portion on which said male fastening tool is to be mounted.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Embodiments of the male fastening tool of the present invention are described below with reference to the drawings.

A male fastening tool1of the present invention is composed of a male fastening tool body2essentially including a body part20having a male screw portion23formed thereon, a flange part21which is formed on an upper end of the body part20and has a seat surface22, to be pressed against a portion on which the male fastening tool1is to be mounted, which is disposed on a periphery of a lower surface thereof, and an annular concave part27formed between the body part20and the seat surface22of the flange part21; and a resinous ring-shaped member3disposed at the annular concave part27of the male fastening tool body2. The annular concave part27of the male fastening tool body2has an annular concave peripheral edge portion29which becomes gradually shallower toward the seat surface. The resinous ring-shaped member3has an annular projected part31which fills almost the entire annular concave part27and a lower surface of which is projected downward beyond the seat surface and an annular peripheral part35, having a tapered bottom surface or a curved bottom surface, which is formed between the annular projected part31and the outer edge33of the resinous ring-shaped member3and becomes gradually thinner, with an outer edge33of the resinous ring-shaped member3being located at an outer edge of the annular concave peripheral edge portion29of the annular concave part27or slightly toward the side of the body part20with respect to the outer edge of the annular concave peripheral edge portion29. The male fastening tool1has an annular concave part34formed between an inner edge22aof the seat surface22and the outer edge33of the resinous ring-shaped member3. The resinous ring-shaped member3deforms when the male fastening tool1is mounted on the portion on which the male fastening tool1is to be mounted, does not restrain the seat surface22from being pressed against the portion on which the male fastening tool1is to be mounted, and forms an annular liquid-tight sealing portion for the portion on which the male fastening tool1is to be mounted.

FIGS. 1 through 7show an embodiment in which the male fastening tool1of the present invention is applied to a sealing plug.

The male fastening tool (sealing plug)1of the present invention is composed of the male fastening tool body (sealing plug body)2and the resinous ring-shaped member3disposed at the annular concave part27of the male fastening tool body2. The sealing plug of this embodiment displays a sealing effect as soon as a fastening work finishes. The sealing plug is capable of holding an axial force as much as ordinary sealing plugs do and displaying the sealing effect at a low torque (axial force). Further the sealing plug of the present invention eliminates the need for incorporating a washer, an O-ring, and the like in the male fastening tool body. Thus the use of the male fastening tool facilitates a fastening work.

The sealing plug body2has the body part20having the male screw portion23formed thereon, the flange part21which is formed on the upper end of the body part20and has the seat surface22to be pressed against the portion on which the sealing plug body2is to be mounted on the periphery of the lower surface thereof, and the annular concave part27formed between the body part20and the seat surface22of the flange part21.

The male fastening tool body2is made of an iron-based steel material such as high-tensile strength steel or stainless steel. As shown inFIGS. 1 through 7, the male fastening tool body (sealing plug body)2has the body part20having the male screw portion23formed on the outer surface thereof and the flange part21which is formed on the upper end of the body part20and has a diameter larger than that of the body part20.

In this embodiment, the body part20is columnar or cylindrical and has a predetermined length comparatively short. The male screw portion23is formed on the entire peripheral surface of the body part20. The male screw portion23may be formed on only a part (for example, the lower end) of the body part20. As shown inFIGS. 3 through 5, a bottom surface20aof the body part20is closed and formed as a flat surface.

The flange part21is disk-shaped and extended radially from the upper end of the body part20. The annular seat surface22is formed on the bottom surface of the flange part21. The seat surface22is formed as an annular flat portion and capable of holding a predetermined axial force when the male fastening tool1is mounted on the portion on which the male fastening tool1is to be mounted. The disk-shaped flange part21has a substantially equal outer diameter. The flange part21is concentric with the body part20(the flange part21and the body part20have the same axis).

As shown inFIGS. 5 and 6, the male fastening tool body (sealing plug body)2has the annular concave part27formed between the body part20and the seat surface22of the flange part21. As shown inFIG. 6, the annular concave part27has a main annular concave portion28extended from a boundary portion between the flange part21and the body part20toward the seat surface22of the flange part21and having an almost equal depth and the annular concave peripheral edge portion29which is formed between the main annular concave portion28and the seat surface22and becomes gradually shallower toward the seat surface22. More specifically the annular concave part27has an annular inclined surface27aextended from the inner edge22aof the seat surface22toward the body part20and an upper surface of the flange part21, an annular flat surface27bwhich is extended from the termination point of the annular inclined surface27atoward the body part20in approximately parallel with the seat surface22, an annular curved surface27ccurvedly extended from the termination point of the annular flat surface27btoward the body part20, and an annular columnar surface27dextended from the termination point of the annular curved surface27cto the body part20. The height (diameter) of the annular columnar surface27dis set lower than a screw thread23aof the body part20(smaller than the diameter of the screw thread) and higher than a thread groove23bof the body part20(larger than the diameter of the thread groove). The annular columnar surface27dcrosses the flange part21and is extended to the body part20. The annular columnar surface27dis continuous with the neighborhood of the thread groove portion forming the termination of the male screw portion23of the body part20. In the male fastening tool1of this embodiment, the outer edge of the lower surface of the flange part21is chamfered.

The male fastening tool body (sealing plug body) of the present invention may be of a type as shown inFIG. 16. A male fastening tool body (sealing plug body)2aof this embodiment has the annular concave part27formed between the body part20and the seat surface22of the flange part21. As shown inFIG. 16, the annular concave part27has a main annular concave portion28awhich is extended from the boundary portion between the flange part21and the body part20toward the seat surface22of the flange part21and has a circular-arc cross section and the annular concave peripheral edge portion29which is formed between the main annular concave portion28and the seat surface22and becomes gradually shallower toward the seat surface22. More specifically the annular concave part27has the annular inclined surface27aextended from the inner edge22aof the seat surface22toward the body part20and the upper surface of the flange part21and an annular circular-arc surface27eextended from the termination point of the annular inclined surface27atoward the body part20. The main annular concave portion28ais formed at the annular circular-arc surface27e. Unlike the above-described male fastening tool body2, the male fastening tool body2adoes not have the main annular concave portion28having almost the equal depth.

The male fastening tool body (sealing plug body) of the present invention may be of a type as shown inFIG. 17. A male fastening tool body (sealing plug body)2bof this embodiment has the annular concave part27formed between the body part20and the seat surface22of the flange part21. As shown inFIG. 17, the annular concave part27has a main annular concave portion28bwhich is extended from a boundary portion between the flange part21and the body part20toward the seat surface22of the flange part21and has a small circular-arc cross section and the annular concave peripheral edge portion29which is formed between the main annular concave portion28band the seat surface22and becomes gradually shallower toward the seat surface22. More specifically, the annular concave part27has the annular inclined surface27aextended from the inner edge22aof the seat surface22toward the body part20and the upper surface of the flange part21, a small annular circular-arc surface27fextended from the termination point of the annular inclined surface27atoward the body part20, and the annular columnar surface27dextended from the termination point of the annular circular-arc surface27fto the body part20. The main annular concave portion28bis formed at the annular circular-arc surface27f. Unlike the above-described male fastening tool body2, the male fastening tool body2bdoes not have the main annular concave portion28having almost the equal depth.

The male fastening tool body (sealing plug body) of the present invention may be of a type as shown inFIG. 18. A male fastening tool body (sealing plug body)2cof this embodiment has the annular concave part27formed between the body part20and the seat surface22of the flange part21. As shown inFIG. 18, the annular concave part27has a main annular concave portion28cextended from the boundary portion between the flange part21and the body part20toward the seat surface22of the flange part21and a small circular-arc cross section and the annular concave peripheral edge portion29which is formed between the main annular concave portion28cand the seat surface22and becomes gradually shallower toward the seat surface22. More specifically the annular concave part27has an annular curved surface27gextended from the inner edge22aof the seat surface22toward the body part20and the upper surface of the flange part21, the annular circular-arc surface27fextended from the termination point of the annular curved surface27gtoward the body part20, and the annular columnar surface27dextended from the termination point of the annular circular-arc surface27fto the body part20. The main annular concave portion28cis formed at the annular circular-arc surface27f. Unlike the above-described male fastening tool body2, the male fastening tool body2cdoes not have the main annular concave portion28having the almost the equal depth. The annular concave peripheral edge portion29is formed not as a tapered surface, but as a curved surface. As shown inFIG. 18, the annular curved surface27gextended from the inner edge22aof the seat surface22toward the body part20and the upper surface of the flange part21is formed as a curved surface having an inflection point in the neighborhood of its center. The annular curved surface27gis formed as a curved surface projected to a low extent at the side of the inner edge22awith respect to the inflection point and as a curved surface concave to a low extent at the side of the annular circular-arc surface27fwith respect to the inflection point.

An outer diameter D of the body part20is favorably 4 to 70 mm and especially favorably 5 to 50 mm. The length of the body part20is favorably 5 to 200 mm and especially favorably 6 to 100 mm. The outer diameter of the flange part21is favorably one to three times larger than the outer diameter D of the body part20and especially favorably 1.2 to 2.0 times larger than the outer diameter D thereof.

A width L1(the distance between the inner edge22aof the seat surface22and the body part20, the distance between the inner edge22aof the seat surface22and the annular columnar surface27dof the annular concave part27) of the annular concave part shown inFIG. 6is favorably 0.05 to 0.8 times and especially favorably 0.1 to 0.6 times larger than the outer diameter D of the body part20. A width L2of the main annular concave portion28of the annular concave part27shown inFIG. 6is favorably 0 to 0.3 times larger than the outer diameter D of the body part20. A depth L3of the annular concave part27is favorably 0.3 to 2.0 mm and especially favorably 0.5 to 1.5 mm. An angle θ1, shown inFIG. 6, formed between the annular inclined surface27aforming the annular concave peripheral edge portion29of the annular concave part27and the seat surface22is favorably 120 degrees to 170 degrees and more favorably 130 degrees to 160 degrees.

Although an effective width M6of the seat surface of the male fastening tool body (sealing plug body)2shown inFIG. 7is different according to the diameter of the male fastening tool (in other words, the outer diameter of the body part20), the effective width M6is preferably 1.5 mm to 5 mm. Although the preferable area of the seat surface22is different according to the outer diameter of the body part20, the area of the seat surface22is preferably 80 mm2to 300 mm2.

In the male fastening tool (sealing plug)1of this embodiment, the male fastening tool body (sealing plug body)2has a tool-mounting hole24extended from the upper surface of the flange part21toward the body part20. The tool-mounting hole24is extended from the center of the upper surface of the flange part21toward the body part20and penetrates through the flange part21. A lower-end surface24aof the tool-mounting hole24is disposed inside the body part20. The tool-mounting hole24has a configuration corresponding to a tool to be used. In this embodiment, the inner surface of the tool-mounting hole24has the configuration of a regular polygonal prism (specifically, regular hexagonal prism). A peripheral edge25of the upper end of the tool-mounting hole24is formed as an annular tapered surface to facilitate insertion of the tool thereinto. The lower-end surface24aof the tool-mounting hole24is tapered and becomes deeper toward the center thereof so that the front end of the inserted tool can be accommodated.

As shown inFIG. 7, the outer edge33of the resinous ring-shaped member3is located at the outer edge22a(the inner edge of the seat surface22) of the annular concave peripheral edge portion29of the annular concave part27or slightly toward the side of the body part20with respect to the outer edge22a(the inner edge of the seat surface22) of the annular concave peripheral edge portion29. The resinous ring-shaped member3has the annular projected part31which fills almost the entire annular concave part27and the lower surface of which is projected downward beyond the seat surface22and the annular peripheral part35, having the tapered bottom surface or the curved bottom surface, which is formed between the annular projected part31and the outer edge33of the resinous ring-shaped member3and becomes gradually thinner toward the outer edge33.

In the resinous ring-shaped member3of this embodiment, as shown inFIG. 7, the lower surface of the annular projected part31projected downward beyond the seat surface22is formed as a flat surface extended toward the outer edge33of the resinous ring-shaped member3on the same level over a predetermined length. The lower surface of the annular projected part31may be formed as a curved surface.

In this embodiment, the annular peripheral part35of the resinous ring-shaped member3has the tapered bottom or the curved bottom surface formed between the annular projected part31and the outer edge33of the resinous ring-shaped member3and becomes gradually thinner toward the outer edge33. The resinous ring-shaped member3is so formed that it does not reach the seat surface22. Therefore in the male fastening tool1, formed between the inner edge22aof the seat surface22and the outer edge of the resinous ring-shaped member3is the annular concave part34having a sectional configuration of an approximately triangle whose vertex consists of the outer edge33of the resinous ring-shaped member3. The outer edge33of the resinous ring-shaped member3may reach the inner edge of the seat surface22, but is required not to be extended to the seat surface.

The outer diameter of the resinous ring-shaped member3is different according to the diameter of the male fastening tool (in other words, the outer diameter of the body part20). The outer diameter of the resinous ring-shaped member3is favorably 0.5 to 2.5 times and especially favorably 0.8 to 2.0 times larger than the outer diameter D of the body part20of the male fastening tool. A projected height M1of the annular projected part31shown inFIG. 7with respect to the seat surface22is favorably 0.05 to 0.5 mm and especially favorably 0.1 to 0.4 mm. A distance M2shown inFIG. 7between the outer edge33of the resinous ring-shaped member3and the inner edge22aof the seat surface22is favorably 0 to 0.7 mm and especially favorably 0.1 to 0.5 mm.

In the male fastening tool1of this embodiment, the resinous ring-shaped member3has a tapered inner-peripheral side projected part36which is extended from an inner peripheral portion of the annular projected part31toward the body part20with the diameter of the tapered inner-peripheral side projected part36decreasing. The tapered inner-peripheral side projected part36is extended in a predetermined length toward the lower end of the body part20. The outer surface of the tapered inner-peripheral side projected part36is formed as an annular tapered surface which decreases in its diameter toward the lower end of the body part20. An end of the tapered inner-peripheral side projected part36fills a thread groove forming the termination portion of the body part20. An angle θ2, shown inFIG. 7, formed between the annular projected part31and the tapered inner-peripheral side projected part36is set to favorably 90 degrees to 180 degrees and especially favorably 120 degrees to 180 degrees. A distance M3shown inFIG. 7between the outer edge of the resinous ring-shaped member3and the outer edge of the tapered inner-peripheral side projected part36is set to preferably 0.1 to 0.6 times larger than the outer diameter D of the body part20of the male fastening tool. A distance M4shown inFIG. 7between the outer edge of the tapered inner-peripheral side projected part36and the annular columnar surface27dof the annular concave part27is set to favorably 0 to 1.0 mm and especially favorably 0 to 0.8 mm. A length M5of the tapered inner-peripheral side projected part36shown inFIG. 7is set to favorably 0 to 3.0 mm and especially favorably 0.5 to 2.0 mm.

The resinous ring-shaped member3deforms when the male fastening tool1is mounted on the portion on which the male fastening tool1is to be mounted, does not restrain the seat surface22from being pressed against the portion on which the male fastening tool1is to be mounted, and forms an annular liquid-tight sealing portion for the portion on which the male fastening tool1is to be mounted.

More specifically as shown inFIGS. 12 through 15, the male fastening tool (sealing plug)1of the present invention is mounted on a portion (for example, parts of a car) of a metal molded product which requires liquid tightness. In an example shown inFIG. 12, a fixing hole having a female screw52is formed on a member5on which the sealing plug1is to be mounted. The sealing plug1of the present invention engages the female screw52of the member5on which the sealing plug1is to be mounted. As shown inFIG. 13, as the engagement proceeds, the resinous ring-shaped member3contacts a surface51of the5member on which the sealing plug1is to be mounted. As the engagement further proceeds, the resinous ring-shaped member3deforms as though it were crushed. More specifically, the resinous ring-shaped member3deforms not in an outer edge direction thereof, but pressed to the central direction thereof to form an annular liquid-tight sealing portion for the member5on which the sealing plug1is to be mounted. When the sealing plug1is fastened at a torque higher than a predetermined torque, the seat surface22of the sealing plug1is pressed against the surface51of the member5on which the sealing plug1is to be mounted. Thereby the mounting work finishes, as shown inFIG. 14. When the sealing plug1is loosened from the member on which the sealing plug1is to be mounted after the elapse of a predetermined period of time, the resinous ring-shaped member3is restorable to a configuration before it is compressed, although it does not completely return to the configuration before it is compressed. Therefore in fastening the sealing plug1again to the member5on which the sealing plug1is to be mounted, the resinous ring-shaped member3forms the annular liquid-tight sealing portion for the portion5on which the sealing plug1is to be mounted.

It is desirable that the resinous ring-shaped member3is formed on the male fastening tool body (sealing plug body)2by insert molding. Therefore as the material forming the resinous ring-shaped member3, thermoplastic resins which can be insert-molded are used. The insert molding herein means that after the formed male fastening tool body (sealing plug body) is inserted into a die, the resinous ring-shaped member is formed by injection of a molten resin. It is preferable that resin to be used contracts a little when it is cooled. By using and insert-molding such a resin, i.e., by using the cooling-caused contraction of the resin forming the resinous ring-shaped member3, the resinous ring-shaped member can be fixed to the male fastening tool body (sealing plug body). Owing to the cooling-caused contraction of the resinous ring-shaped member, the inner diameter thereof contracts in a diameter decrease direction. Thereby the resinous ring-shaped member which preferably adheres to the male fastening tool body (sealing plug body) is formed. In other words, owing to the deformation (compression) of the resinous ring-shaped member, a crimped state in which the resinous ring-shaped member has adhered to the male fastening tool body (sealing plug body) is formed.

The material forming the resinous ring-shaped member3has a flexural modulus of elasticity of favorably 200 to 3000 MPa and especially favorably 500 to 2500 MPa and a tensile elongation after fracture of favorably 5 to 300% and especially favorably 15 to 200%.

As examples of materials forming the resinous ring-shaped member3, it is possible to use synthetic rubber such as urethane rubber, silicone rubber, butadiene rubber, propylene rubber; natural rubber such as latex rubber; and elastomers such as olefin elastomers (polyethylene elastomer, polypropylene elastomer); amide elastomers (polyamide elastomer); styrene elastomers (for example, styrene-butadiene-styrene copolymer, styrene-isoprene-styrene copolymer, styrene-ethylene butylene-styrene copolymer); urethane elastomers (polyurethane elastomer of polyester family, polyurethane elastomer of polyether family).

The male fastening tool of the present invention is not limited to the above-described sealing plug, but may be applied to a sealing bolt shown inFIGS. 8 through 11.

A sealing bolt10of this embodiment is different from the sealing plug1in that the body of the male fastening tool is not the body of the sealing plug, but is the body of the sealing bolt. The form of the annular concave part of the sealing bolt10and that of the resinous ring-shaped member thereof are the same as those of the above-described sealing plug1.

The sealing bolt10of this embodiment is composed of a sealing bolt body11essentially having a body part12having a male screw portion15, a flange part17which is formed on the upper end of the body part12and has a seat surface18, to be pressed against a portion on which the sealing bolt10is to be mounted, which is disposed on the periphery of the lower surface thereof, and the annular concave part27formed between the body part12and the seat surface18of the flange part17; and the resinous ring-shaped member3disposed at the annular concave part27of the sealing bolt body11. The annular concave part27of the sealing bolt body11has a main annular concave portion extended from a boundary portion disposed between the flange part17and the body part12toward the seat surface18of the flange part17and having an almost equal depth and an annular concave peripheral edge portion which is formed between the main annular concave portion and the seat surface18and becomes gradually shallower toward the seat surface. The resinous ring-shaped member3is located slightly toward the side of the body part12with respect to the outer edge of the annular concave peripheral edge portion of the annular concave part27. The resinous ring-shaped member3has an annular projected part (annular main part) which fills almost the entire annular concave part27and a lower surface of which is projected downward beyond the seat surface and an annular peripheral part, having a tapered bottom surface or a curved bottom surface, which is formed between the annular projected part and the outer edge of the resinous ring-shaped member3and becomes gradually thinner. In the sealing bolt10of this embodiment, formed between an inner edge of the seat surface18and the outer edge of the resinous ring-shaped member3is the annular concave part having a sectional configuration of an approximately triangle whose vertex consists of the outer edge of the resinous ring-shaped member3. The resinous ring-shaped member3deforms when the resinous ring-shaped member3is mounted on the portion on which the sealing bolt10is to be mounted, does not restrain the seat surface18from being pressed against the portion on which the sealing bolt10is to be mounted, and forms an annular liquid-tight sealing portion for the portion on which the sealing bolt10is to be mounted.

FIGS. 8 through 11show an embodiment in which the male fastening tool of the present invention is applied to the sealing bolt.

The male fastening tool (sealing bolt)10of this embodiment is composed of the male fastening tool body (sealing bolt body)11and the resinous ring-shaped member3disposed at the annular concave part27of the male fastening tool body (sealing bolt body)11. The sealing bolt of this embodiment displays a sealing effect as soon as a fastening work finishes. The sealing bolt is capable of holding an axial force as much as ordinary sealing bolts do and displaying the sealing effect at a low torque (axial force). Further the sealing bolt10eliminates the need for incorporating a washer, an O-ring, and the like in the male fastening tool body. Thus the use of the male fastening tool facilitates a fastening work.

The sealing bolt body11is made of an iron-based steel material such as high-tensile strength steel or stainless steel. As shown inFIGS. 8 through 11, the sealing bolt body11has the body part12having the male screw portion15, the flange part17formed on the upper end of the body part12, and a head part16formed on the upper end of the flange part17. The male screw is formed on the body part12entirely or at a portion of the outer surface thereof. In this embodiment, the head part16is formed on the upper end of the flange part17. The head part16is so formed that it has an outer diameter larger than that of the body part11and a polygonal configuration to allow a rotational operation to be performed with a wrench or the like.

The flange part17is formed on the lower end of the head part16and has an outer diameter larger than that of the head part16. The flange part17has a disk-shaped body portion and the seat surface18composed of a lower surface of the body portion of the flange part17. The seat surface18is formed as a flat portion and capable of holding a predetermined axial force when the male sealing bolt10is mounted on the portion on which the sealing bolt10is to be mounted. In the male sealing bolt10of this embodiment, the diameter of the upper surface of the flange part formed as a tapered portion becomes smaller toward the head part16.

It is preferable that in the sealing bolt10of this embodiment, the form of the annular concave part and that of the resinous ring-shaped member are the same as those of the male fastening tool of the above-described embodiment.

EXAMPLES

Using steel, a sealing plug body having a flange part whose diameter was φ33.5 mm and thickness was 3.5 mm, a body part, having a diameter of φ24 mm, which had a male screw having a length of 7.5 mm, and an annular concave part having a configuration shown inFIGS. 1 through 7was prepared.

The width L1(the distance between the inner edge22aof the seat surface22and the body part20, the distance between the inner edge22aof the seat surface22and the annular columnar surface27dof the annular concave part27) of the annular concave part of the prepared sealing plug body shown inFIG. 6was 3.75 mm. The width L2of the main annular concave portion28of the annular concave part27shown inFIG. 6was 1.5 mm. The depth L3of the annular concave part27shown inFIG. 6was 1.0 mm. The angle θ1, shown in FIG.6, which was formed between the annular inclined surface27aforming the annular concave peripheral edge portion29of the annular concave part27and the seat surface22was 150 degrees. The effective width M6of the seat surface22shown inFIG. 7was 1.87 mm.

The sealing plug which is the male fastening tool of the present invention was prepared by inserting the prepared sealing plug body into a die, injecting molten resin (PPE: polyphenylene ether) thereinto, and forming the resinous ring-shaped member having a form as shown inFIGS. 1 through 7in the annular concave part of the sealing plug body.

The projected height M1of the resinous ring-shaped member3of the prepared sealing plug shown inFIG. 7with respect to the seat surface22was 0.25 mm. The distance M2shown inFIG. 7between the outer edge33of the resinous ring-shaped member3and the inner edge22aof the seat surface22was 0.15 mm. The distance M3shown inFIG. 7between the outer edge of the resinous ring-shaped member3and the outer edge of the tapered inner-peripheral side projected part36was 2.38 mm. The distance M4shown inFIG. 7between the outer edge of the tapered inner-peripheral side projected part36and the annular columnar surface27dof the annular concave part27was 0.5 mm. The length M5of the tapered inner-peripheral side projected part36shown inFIG. 7was 1.0 mm. The angle θ2, shown inFIG. 7, which was formed between the annular projected part31and the tapered inner-peripheral side projected part36was 125 degrees.

Using steel, a sealing plug body having a flange part whose diameter was φ19 mm and thickness was 3 mm, a body part, having a diameter of φ10 mm, which had a male screw having a length of 11 mm, and an annular concave part having a configuration shown inFIGS. 1 through 7was prepared.

The width L1(the distance between the inner edge22aof the seat surface22and the body part20, the distance between the inner edge22aof the seat surface22and the annular columnar surface27dof the annular concave part27) of the annular concave part of the prepared sealing plug body shown inFIG. 6was 3.12 mm. The width L2of the main annular concave portion28of the annular concave part27shown inFIG. 6was 1.58 mm. The depth L3of the annular concave part27shown inFIG. 6was 1.0 mm. The angle θ1, shown inFIG. 6, which was formed between the annular inclined surface27aforming the annular concave peripheral edge portion29of the annular concave part27and the seat surface22was 135 degrees. The effective width M6of the seat surface22shown inFIG. 7was 1.88 mm.

The sealing plug which is the male fastening tool of the present invention was prepared by inserting the prepared sealing plug body into the die, injecting molten resin (PPE: polyphenylene ether) thereinto, and forming the resinous ring-shaped member having the form as shown inFIGS. 1 through 7in the annular concave part of the sealing plug body.

The projected height M1of the resinous ring-shaped member3of the prepared sealing plug shown inFIG. 7with respect to the seat surface22was 0.25 mm. The distance M2shown inFIG. 7between the outer edge33of the resinous ring-shaped member3and the inner edge22aof the seat surface22was 0.25 mm. The distance M3shown inFIG. 7between the outer edge of the resinous ring-shaped member3and the outer edge of the tapered inner-peripheral side projected part36was 2.66 mm. The distance M4shown inFIG. 7between the outer edge of the tapered inner-peripheral side projected part36and the annular columnar surface27dof the annular concave part27was 0.25 mm. The length M5of the tapered inner-peripheral side projected part36shown inFIG. 7was 1.5 mm. The angle θ2, shown inFIG. 7, which was formed between the annular projected part31and the tapered inner-peripheral side projected part36was 102 degrees.

Using steel, a sealing bolt body having a flange part whose diameter was φ14.5 mm and thickness was 1.5 mm, a body part, having a diameter of φ6 mm, which had a male screw having a length of 35 mm, and an annular concave part having a configuration shown inFIGS. 8 through 11was prepared.

The width L1(the distance between the inner edge22aof the seat surface22and the body part20, the distance between the inner edge22aof the seat surface22and an annular columnar surface27dof the annular concave part27) of the annular concave part of the prepared sealing bolt body shown inFIG. 6was 2.96 mm. The width L2of the main annular concave portion28of the annular concave part27was 0.82 mm. The depth L3of the annular concave part27was 0.9 mm. The angle θ1, shown inFIG. 6, which was formed between the annular inclined surface27aforming the annular concave peripheral edge portion29of the annular concave part27and the seat surface22was 138 degrees. The effective width M6of the seat surface22shown inFIG. 7was 2.25 mm.

The sealing bolt which is the male fastening tool of the present invention was prepared by inserting the prepared sealing plug body into the die, injecting the molten resin (PPE: polyphenylene ether) thereinto, and forming the resinous ring-shaped member in the annular concave part of the sealing bolt body.

The projected height M1of the resinous ring-shaped member3of the prepared sealing plug shown inFIG. 7with respect to the seat surface22was 0.25. The distance M2shown inFIG. 7between the outer edge33of the resinous ring-shaped member3and the inner edge22aof the seat surface22was 0 mm. The distance M3shown inFIG. 7between the outer edge of the resinous ring-shaped member3and the outer edge of the tapered inner-peripheral side projected part36was 2.47 mm. The distance M4shown inFIG. 7between the outer edge of the tapered inner-peripheral side projected part36and the annular columnar surface27dof the annular concave part27was 0.46 mm. The length M5of the tapered inner-peripheral side projected part36shown inFIG. 7was 0 mm. The angle θ2, shown inFIG. 7, which was formed between the annular projected part31and the tapered inner-peripheral side projected part36was 180 degrees.

Comparison Example 1

The sealing plug body of example 1 (did not have the resinous ring-shaped member) was used as the sealing plug of the comparison example 1.

Comparison Example 2

The sealing plug body of example 1 (did not have the resinous ring-shaped member) having a copper washer mounted thereon was used as the sealing plug of the comparison example 2.

Comparison Example 3

The sealing plug body of example 1 (did not have the resinous ring-shaped member) having an aluminum washer mounted thereon was used as the sealing plug of the comparison example 3.

Comparison Example 4

The sealing plug body of example 1 (did not have the resinous ring-shaped member) having a stainless steel (SUS) washer mounted thereon was used as the sealing plug of the comparison example 4.

Comparison Example 5

The sealing bolt body of example 3 (did not have the resinous ring-shaped member) was used as the sealing bolt of the comparison example 5.

Comparison Example 6

The sealing bolt body of example 3 (did not have the resinous ring-shaped member) having the copper washer mounted thereon was used as the sealing bolt of the comparison example 6.

Comparison Example 7

The sealing bolt body of example 3 (did not have the resinous ring-shaped member) having the aluminum washer mounted thereon was used as the sealing bolt of the comparison example 7.

Comparison Example 8

The sealing bolt body of example 3 (did not have the resinous ring-shaped member) having the stainless steel (SUS) washer mounted thereon was used as the sealing bolt of the comparison example 8.

Experiments for measuring the axial force-holding properties of the sealing plugs of the example 1 and the comparison examples 1 through 4 were conducted.

A plurality of the sealing plugs of the example 1 and the comparison examples 1 through 4 was prepared. Each of the sealing plugs was mounted on a seat surface plate made of iron by setting the length between clamped points of each sealing plug to 2 mm and the axial force to 800 kgf (computed from the elongated length of the sealing plug).

After seat surface plates on which the sealing plugs were mounted respectively were left for 100 hours in respective high-temperature baths set to various temperatures, the seat surface plates were taken out. After the temperatures of the sealing plugs and those of the seat surface plates became normal, the residual elongation amount of each of the sealing plugs was measured to compute the residual axial force thereof. The results are as shown below.

Experiments for measuring the sealing properties of the sealing plugs of the example 1 and the comparison examples 1 through 4 were conducted.

Using a leak-examining jig made of stainless steel which had a plug-mounting hole having a female screw formed on its inner surface and an air path communicating with the plug-mounting hole, each sealing plug was mounted on the leak-examining jig at a clamping torque of 10 to 60 N·m. After an air pressure (1 MPa) was applied to the air path of the leak-examining jig, the leak-examining jig was immersed in water. Whether air leaked from the vicinity of the flange of each sealing plug was visually checked 10 minutes later.

Air leak was found on the sealing bolts of all of the example 1 and the comparison examples 1 through 4.

2) Clamping Torque 30 N m

Air leak was not found on the sealing bolt of the example 1, but found on the sealing bolts of the comparison examples 1 through 4.

3) Clamping Torque 40 N m

Air leak was not found on the sealing bolts of the example 1 and the comparison example 2, but found on the sealing bolts of the comparison examples 1, 3, and 4.

4) Clamping Torque 50 N m

Air leak was not found on the sealing bolts of the example 1 and the comparison examples 2 and 3, but found on the sealing bolts of the comparison examples 1 and 4.

5) Clamping Torque 60 N m

Air leak was not found on the sealing bolts of the example 1 and the comparison examples 2 through 4, but found on the sealing bolt of the comparison example 1.

Experiments for measuring the axial force-holding properties of the sealing bolts of the example 3 and the comparison examples 5 through 8 were conducted.

A plurality of the sealing bolts of the example 3 and the comparison examples 5 through 8 was prepared. Each of the sealing bolts was mounted on a seat surface plate made of iron by setting the length between clamped points of each sealing bolt to 25 mm and the axial force to 800 kgf (computed from the elongated length of the sealing bolt).

After seat surface plates on which the sealing plugs were mounted respectively were left for 100 hours in respective high-temperature baths set to various temperatures, the seat surface plates were taken out. After the temperatures of the sealing plugs and those of the seat surface plates became normal, the residual elongation amount of each of the sealing plugs was measured to compute the residual axial force thereof. The results are as shown below.

Experiments for measuring the sealing properties of the sealing bolts of the example 3 and the comparison examples 5 through 8 were conducted.

Using a leak-examining jig made of stainless steel having a bolt-mounting hole having a female screw formed on its inner surface and an air path communicating with the bolt-mounting hole, each sealing bolt was mounted on the leak-examining jig at a clamping torque of 1 to 9 N m. After an air pressure (1 MPa) was applied to the air path of the leak-examining jig, the leak-examining jig was immersed in water. Whether air leaked from the vicinity of the flange of each sealing bolt was visually checked 10 minutes later.

Air leak was found on the sealing bolts of the example 3 and the comparison examples 5 through 8.

2) Clamping Torque N m

Air leak was not found on the sealing bolt of the example 3, but found on the sealing bolts of the comparison examples 5 through 8.

3) Clamping Torque 5 N m

Air leak was not found on the sealing bolt of the example 3, but found on the sealing bolts of the comparison examples 5 through 8.

4) Clamping Torque 6 N m

Air leak was not found on the sealing bolts of the example 3 and the comparison example 6, but found on the sealing bolts of the comparison examples 5, 7, and 8.

Air leak was not found on the sealing bolts of the example 3 and the comparison examples 6 and 7, but found on the sealing bolts of the comparison examples 5 and 8.

The male fastening tool of the present invention is composed of the male fastening tool body essentially including the body part having the male screw portion formed thereon, the flange part which is formed on the upper end of the body part and has the seat surface, to be pressed against the portion on which the male fastening tool is to be mounted, which is disposed on the periphery of the lower surface thereof, and the annular concave part formed between the body part and the seat surface of the flange part; and the resinous ring-shaped member disposed at the annular concave part of the male fastening tool body. The annular concave part of the male fastening tool body further includes the annular concave peripheral edge portion which becomes gradually shallower toward the seat surface. The outer edge of the resinous ring-shaped member is located at the outer edge of the annular concave peripheral edge portion of the annular concave part or slightly toward the side of the body part with respect to the outer edge of the annular concave peripheral edge portion. The resinous ring-shaped member has the annular projected part which fills almost the entirety of the annular concave part and the lower surface of which is projected downward beyond the seat surface and the annular peripheral part, having the tapered bottom surface or the curved bottom surface, which is formed between the annular projected part and the outer edge of the resinous ring-shaped member and becomes gradually thinner. The resinous ring-shaped member deforms when the male fastening tool is mounted on the portion on which the male fastening tool is to be mounted, does not restrain the seat surface from being pressed against the portion on which the male fastening tool is to be mounted, and forms the annular liquid-tight sealing portion for the portion on which the male fastening tool is to be mounted.

Therefore when the male fastening tool of the present invention is mounted on the portion to which a member is fastened by tightening the male fastening tool, the male fastening tool is capable of securely liquid-tightly sealing the above-described portion, and the axial force can be held by the seat surface of the flange part of the male fastening tool body. Further the resinous ring-shaped member fixed to the male fastening tool body to seal the portion does not cause the male fastening tool to be very large.