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Title: Boring apparatus provided with drill bits freely rotatable around their own axis
Claims: I claim: 1. A boring apparatus for boring holes in the ground comprising a plurality of downward extending drill bits and associated drill bit shafts, and a boring pipe, each said drill bit shaft and said boring pipe being rotatably supported in a casing assembly, each said drill bit shaft being rotatably journaled in an associated means for supporting each said drill bit shaft such that each said drill bit is freely rotatable about the axis of rotation of said associated drill bit shaft, said means arranged and configured such that the axis of rotation of each said drill bit shaft is substantially parallel to the axis of rotation of said boring pipe, said means for supporting each said drill bit shaft being coupled to said boring pipe, such that said means is non-rotatable about its own axis, said means being further characterized by an absence of any gear engaging member for engaging said boring pipe disposed along the outer periphery thereof, said boring pipe being disposed in said casing assembly such that said drill bit shafts circumferentially surround said boring pipe, said boring pipe being further characterized by a lack of any gear engaging members for engaging said means for supporting said drill bit shaft, said casing assembly coupling said boring pipe to each said drill bit shaft such that rotation of said casing assembly causes (i) said boring pipe to axially rotate; (ii) said means for supporting each said drill bit shaft to revolve about said axis of said boring pipe; and (iii) each said drill bit shaft and drill bit to rotate about said axis of said drill bit shaft in a direction of rotation opposite to the direction of rotation of said boring pipe. 2. The boring apparatus as claimed in claim 1, wherein said casing assembly comprises (i) a central casing coupled to said boring pipe, and (ii) bit-supporting casings, said bit-supporting casing being detachably secured to said central casing. 3. The boring apparatus as claimed in claim 2, wherein a block member of a predetermined thickness is interposed between said central casing and each said bit-supporting casings, thereby permitting selective adjustment of the pitch of said bits. 4. The boring apparatus as claimed in claim 1, wherein a predetermined number of said drill bits have their axis inclined inwardly toward the direction of said boring pipe relative to the axis of rotation of said boring pipe. 5. The boring apparatus as claimed in claim 1, wherein a predetermined number of said drill bits have their cutting edge surfaces arranged to lie in an axially offset relation from each other. 6. The boring apparatus as claimed in claim 1, wherein said casing is provided at the outer side thereof with a bore reshaping bit. 7. The boring apparatus as claimed in claim 2, wherein said boring pipe and said central casing coupled to said boring pipe are hollow, and an opening is provided in the lower end of said central casing. 8. The boring apparatus as claimed in claim 1, wherein an interlocking means is provided on said plurality of bits for causing rotation of said plurality of drill bits around their said axis of rotation and thereby interlocking with one another. 9. The boring apparatus as claimed in claim 8, wherein said interlocking means comprises a train of gears. 10. The boring apparatus as claimed in claim 8, wherein said interlocking means comprises a chain means. 11. The boring apparatus according to claim 1 wherein said means for supporting each said drill bit shaft is a bit-supporting casing circumferentially disposed about each said shaft adjacent the lower end of each said shaft, and said boring pipe is journaled in a central casing, each said bit-supporting casing being coupled to said central casing thereby forming said casing assembly. 12. The boring apparatus according to claim 11 wherein at least one boring reshaping bit is coupled to said bit-supporting casing such that said reshaping bit extends outward from and perpendicular to said bit-supporting casing. 13. The boring apparatus according to claim 1 wherein said means for supporting each said drill bit shaft is coupled to said boring pipe with a block member selectively disposed between said means for supporting each said drill bit shaft and said boring pipe, said block member thereby changing the pitch of said drill bits. 14. The boring apparatus according to claim 11 wherein a block member of a predetermined thickness is interposed between said central casing and each said bit-supporting casings thereby permitting selective adjustment of the pitch of said bits. Other info: Inventors: Ikeda, Nobuhisa (Yokohama, JA) Application Number: 512067 Filing Date: 1974-10-04 Publication_date: 1976-03-23 Assignee: Tone Boring Company Limited (Tokyo, JA) Primary Class(es): 175/319 Other Classes: US Patent Ref:
Other Refs:
Primary Examiner: Leppink, James A. Assistant Examiner: Attorney: Spensley, Horn and Lubitz |
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