Claims
- 1. A boring casing of the type which can be connected together to extend the drilling column of an earth boring machine, comprising:
- (a) a short length metal pipe connector arranged at each end of the boring casing for connecting successive casing to each other or to metal drilling pipes, each of said short length metal pipe connectors having an uneven surface on its outer periphery;
- (b) an inner pipe structure composed of a plurality of coaxial fiber-reinforced plastic layers, said inner pipe abutting at each of its ends against a respective one of the short length metal pipe connectors;
- (c) an outer pipe structure laminated over and covering the outer peripheries of said inner pipe structure and the uneven surfaces of said short length metal pipe connectors, said outer pipe composed of a plurality of coaxial fiber-reinforced plastic layers;
- (d) an outer protective layer formed by a metal sleeve which is provided on the surface of the outermost layer of the outer pipe structure; and
- (e) wherein said coaxial fiber-reinforced plastic layers include:
- (i) at least one fiber-reinforced plastic layer whose reinforcing fibers are carbon fibers arranged in the axial direction of the boring casing, and
- (ii) at least one fiber-reinforced plastic layer whose reinforcing fibers are arranged 90.degree. to the axial direction of the boring casing.
- 2. A boring casing as in claim 1, wherein said carbon fibers arranged in the axial direction have an elastic modulus of more than 240 GPa.
- 3. A boring casing as in claim 2, wherein said carbon fibers arranged in the axial direction have an elastic modulus in the range of 400 to 800 GPa.
- 4. A boring casing of claim 1, wherein if only one of said plurality of fiber-reinforced plastic layers has carbon reinforcing fibers arranged in the axial direction, that one layer is in the outer pipe.
- 5. A boring casing as in claim 1, wherein at least one of said plurality of fiber-reinforced plastic layers of each of said inner pipe and said outer pipe is a layer whose reinforcing fibers are carbon fibers arranged in the axial direction of the boring casing.
- 6. A boring casing as in claim 5, wherein said carbon fibers arranged in the axial direction have an elastic modulus of more than 240 GPa, preferably in the range of 400 to 800 GPa.
- 7. A boring casing as in claim 1, wherein at least the outermost layer of the outer pipe structure is a layer having its reinforcing fibers arranged 90.degree. to the axial direction.
- 8. A boring casing as in claim 7, wherein the innermost layer of the inner pipe structure is a layer having whose reinforcing fibers are arranged 90.degree. to the axial direction.
- 9. A boring casing as in claim 1, further comprising the innermost layer of the inner pipe structure being a protective layer formed with glass fibers.
- 10. A boring casing as in one claim 1 or claim 5, wherein glass fibers or aramid fibers are employed as the reinforcing fibers except for the layers having said axially arranged carbon reinforcing fibers, and wherein the matrix resin is a resin selected from the group consisting of:
- the following thermosetting resins:
- epoxy resin, unsaturated polyester resin, urethane acrylate, vinyl ester, phenol, or polyurethane, and
- the following thermo-plastic resins:
- polyamide 6, polyamide 66, polyamide 12, polybutylene terephthalate, polyethylene terephthalate, polycarbonate, polyacetal, polyphenylene sulfide, polyether ether ketone, polyether sulfide, polyphenylene oxide, modified polyphenylene oxide, polypropylene, or polyvinyl.
Priority Claims (2)
Number |
Date |
Country |
Kind |
63-156140 |
Jun 1988 |
JPX |
|
1-82846 |
Mar 1989 |
JPX |
|
Parent Case Info
This is a continuation of Ser. No. 07/686,108 filed Apr. 16, 1991, abandoned which is a continuation of Ser. No. 07/338,266 filed Apr. 14, 1989, abandoned.
US Referenced Citations (13)
Foreign Referenced Citations (1)
Number |
Date |
Country |
2271024 |
Dec 1975 |
FRX |
Continuations (2)
|
Number |
Date |
Country |
Parent |
686108 |
Apr 1991 |
|
Parent |
338266 |
Apr 1989 |
|