Pipe joints or couplings – Packed – Wedge
Reexamination Certificate
2000-02-24
2002-03-19
Dayoan, B. (Department: 3627)
Pipe joints or couplings
Packed
Wedge
C285S039000, C285S321000, C285S339000, C285S423000, C264S135000, C264S269000, C264S297100, C264S297200, C264S297800, C525S166000
Reexamination Certificate
active
06357802
ABSTRACT:
FIELD OF ART
This invention relates to a pipe made of a rigid thermoplastic resin, a pipe joint structure, and manufacturing methods thereof, and more particularly to a pipe made of a rigid thermoplastic resin which is suitable as a pipe joint incorporating a sealing structure, a specific pipe joint structure, and their manufacturing methods.
BACKGROUND ART
A pipe joint, for example, an air-pressure joint usually secures a seal between an outer side (atmospheric air side) and an inner side (high pressure side) by using a non-integral O-ring or a ring-shaped gasket between a joint main body (pipe main body) and a pipe to be connected.
Further, a rigid synthetic resin is used for the joint main body; and a rubber or a flexible synthetic resin having an elasticity is used for the O-ring or the ring-shaped gasket, respectively.
However, since the O-ring is a flexible component which is smaller relative to the joint main body, and moreover, an attachment position is at an inner surface of the joint main body where the attaching is difficult, there has been a problem that an entanglement (twist) is generated in connecting with the pipe to be connected or in assembling the joint main body, causing leakage of a fluid or providing poor workability.
DISCLOSURE OF THE INVENTION
This invention provides a pipe made of a rigid thermoplastic resin in which a ring-shaped projection comprising an elastic resin and having a sealing property is integrally molded to an inner surface thereof thermoplastically.
In other words, this invention makes it possible to prevent generation of entanglement (twist) or leakage of a fluid and also makes it possible to improve the poorness of the operability accompanying the mounting, by integrally molding a pipe main body and a ring-shaped projection (which may be hereafter referred to as a ring-shaped projecting streak) streak having a sealing property along its inner surface directly (without intervention of a third component such as an adhesive) with a combination of a specific rigid thermoplastic resin and a specific elastic resin, respectively.
Now, the rigid thermoplastic resin to be used for the pipe (pipe main body) in the present invention may be, for example, a polyphenylene ether resin (a polyphenylene oxide resin), a polyamide resin, a polyester resin, a polyvinyl chloride resin, or an AS resin. Specifically, the polyester resin may be polybutylene terephthalate; the polyphenylene ether resin may be a mixture of polyphenylene ether and impact-resistant polystyrene; and the polyamide may be polyamide 46, polyamide 6, polyamide 66, polyamide 12, polyamide 612, polyamide 610 and the like, as preferable examples.
On the other hand, the elastic resin to be used for the ring-shaped projecting streak may be, for example, a butadiene-acrylonitrile rubber, a styrene-butadiene rubber, a nitrile rubber, a natural rubber, an ethylene propylene rubber, a chloroprene rubber, a fluorine rubber, a silicone rubber or a mixture thereof. Specifically, diene elastomers such as a butadiene rubber, a styrene-butadiene rubber, a chloroprene rubber, a butadiene-acrylonitrile rubber (a nitrile butadiene rubber) and the like, non-diene elastomers such as a isobutylene-isoprene copolymer, an ethylene-propylene, copolymer, chlorosulfonated polyethylene, chlorinated polyethylene and the like, thermoplastic elastomers such as a block copolymer of styrene and butadiene or isoprene, natural rubbers and the like are given as examples. These elastomers may be vulcanized and also may have a carboxyl group introduced by acrylic acid, methacrylic acid, sorbic acid or the like.
By combining the rigid thermoplastic resin and the elastic resin as mentioned above as materials for the pipe main body and the ring-shaped projection, the two can be integrally bonded thermoplastically. For details of further example materials and condition combinations, reference is made to each of Japanese Unexamined Patent Publication No. SHO 62(1987)-21244, Japanese Unexamined Patent Publication No. HEI 01(1989)-149854, Japanese Unexamined Patent Publication No. HEI 02(1990)-150439, Japanese Unexamined Patent Publication No. HEI 03(1991)-133631, Japanese Unexamined Patent Publication No. HEI 03(1991)-138144, Japanese Examined Patent Publication No. HEI 05(1993)-30182, Japanese Unexamined Patent Publication No. HEI 07(1995)-11013 and Japanese Examined Patent Publication No. HEI 08(1996)-18412.
In the present invention, the “sealing property” for the ring-shaped projecting streak means that the sealing (seal) can be made by pressing contact with a tube to be connected, and is a property that can be obtained from use of the above-mentioned elastic resin by its physical property.
The pipe made of a rigid thermoplastic resin pertaining to the present invention can be manufactured by using materials and combinations as mentioned above by means of a manufacturing method such as follows.
In other words, the pipe made of a rigid thermoplastic resin pertaining to the present invention is manufactured by simultaneously or successively passing through a pipe main body molding step for molding a pipe main body and a ring-shaped projecting streak molding step for disposing a ring-shaped projecting streak on an inner surface of the pipe main body.
In the pipe main body molding step, the pipe main body is molded by injecting a molten material of the rigid thermoplastic resin (a source material of the rigid thermoplastic resin) into a tubular cavity (gap) formed by a set of molds which are splittable into a plurality.
Next, in the ring-shaped projecting streak molding step, the ring-shaped projecting streak made of the elastic resin and having the sealing property is integrally molded thermoplastically on an inner surface of the pipe main body by injecting a molten material of the elastic resin (concretely, an unvulcanized molten body as a source material or a material of a rubber) into a ring-shaped cavity formed a long the inner surface of the pipe main body by the molds themselves or combining another mold and vulcanizing it.
On the other hand, in the case where this ring-shaped projecting streak is to be molded simultaneously with the pipe main body, a manufacturing method of a pipe made of a rigid thermoplastic resin can be provided which comprises injecting, into a cavity formed by the splittable molds and comprising a pipe-shaped portion and a ring-shaped portion located along an inner surface of this pipe-shaped portion, a molten material of the rigid thermoplastic resin into the pipe-shaped portion and a molten material of the elastic resin into the ring-shaped portion of the cavity for simultaneous integral molding to obtain the pipe made of the rigid thermoplastic resin having the ring-shaped projecting streak on the inner surface of the pipe main body.
Here, if an injection inlet is formed in an inner mold of the molds, the material of the elastic resin in a molten state can be injected into the ring-shaped cavity located along the inner surface of the pipe main body. However, it is convenient if a through-hole is formed beforehand in a trunk portion of the pipe main body (using a slide pin) and the material of the elastic resin in a molten state is injected into the ring-shaped cavity using the through hole.
In the manner mentioned above, the ring-shaped projecting streak having a sealing property and made of an elastic resin is molded in a thermoplastically and integrally bonded state along the inner surface of the pipe main body made of the rigid thermoplastic resin by the pipe main body molding step and the ring-shaped projecting streak molding step.
The obtained pipe made of the rigid thermoplastic resin is convenient for connection of tubes and is especially suitable as a pipe joint that passes a pressurized gas containing air inside, water, oil or the like relative to the outside ambient air, because a sealing effect that does not allow passing of a gas such as air or liquid can be obtained when another tube is brought into close contact with the ring-shaped projecting streak having the sealing property,
Hiraishi Masanori
Inagaki Atsushi
Komada Hajime
Matsumoto Shin-ichi
Mutsuda Mitsuteru
Birch & Stewart Kolasch & Birch, LLP
Dayoan B.
Lugo Carlos
Mikuni Plastics Co., Ltd.
LandOfFree
Pipe of hard thermoplastic resin, pipe joint structure and... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Pipe of hard thermoplastic resin, pipe joint structure and..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Pipe of hard thermoplastic resin, pipe joint structure and... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2848550