Drilling device for enlarged-diameter hole
AssigneeKabushiki Kaisha Miyanaga
InventorMasaaki Miyanaga
Life of this patent
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Abstract
A drilling device for forming an enlarged-diameter hole includes: a guide sleeve with a cylindrical body and a guide to be inserted into a bottomed hole; a slide body that slides in the cylindrical body; and a bit holder provided on the slide body swingably; and a diameter-enlarging bit with a cutting blade. The bit slides between a first position where the cutting blade is separated from a bottom of the bottomed hole and a second position where the cutting blade is closer to the bottom than that at the first position. The guide has: a guide piece that guides the cutting blade to a side part, of the bottomed hole, following an advance of the bit from the first position to the second position; and an opening which allows passage of the bit removed from the bit holder where the bit is at the first position.
Claims4
A drilling device for forming an enlarged-diameter hole in a deep bottom of a bottomed hole opened in an object to be drilled, the drilling device comprising:
- a guide sleeve including a guide to be inserted into the bottomed hole and a cylindrical body continuous with the guide;
- a slide body provided so as to be movable back and forth in the cylindrical body;
- a bit holder located in front of the slide body and provided on the slide body so as to be swingable in the cylindrical body;
- and
- a diameter-enlarging bit located in front of the bit holder, detachably fitted to the bit holder, and provided with a cutting blade at a front end, wherein
- following the back and forth movement of the slide body, the diameter-enlarging bit is provided so as to be movable back and forth between a first position at which the cutting blade is separated from a bottom of the bottomed hole and a second position at which the cutting blade is closer to the bottom of the bottomed hole than the cutting blade at the first position,
- the guide has a guide piece that guides the cutting blade to a side surface part, of the bottomed hole, corresponding to the enlarged-diameter hole following an advance of the diameter-enlarging bit from the first position to the second position, and an opening formed with a size allowing passage of the diameter-enlarging bit beyond the opening of the guide, and
- a center hole extending in a longitudinal direction of the bit holder is opened in the bit holder, and the bit holder is detachably fitted on the diameter-enlarging bit by fitting the diameter-enlarging bit in the center hole and by fitting a ball provided inside a periphery of the bit holder and biased toward the center hole into a recess formed in the diameter-enlarging bit.
Dependencies are inferred from the claim text.