Externally threaded bodies for use as taps or screws
OwnerAnton Harleinventor
Life of this patent
Estimating the term…
Abstract
There is provided set of at least two externally threaded bodies each of which has a cylindrical external surface provided with a screw thread. The screw threads have identical pitches, and the crest diameter or diameters of one or more helices of one of the screw threads is or are larger than the crest diameters of helices of the other screw thread. The externally threaded bodies can constitute screws or taps for use in osteosynthesis. If a screw becomes loose, it is removed and the hole for such screw is tapped with a larger tap prior to insertion of a screw having helices with crest diameters larger than the crest diameters of helices of the removed screw. The core diameters of the screw threads of a set of externally threaded bodies need not be the same.
Claims24
A set of thread cutting taps each arranged to cut a final and usable female thread and each having a crest diameter and a root diameter, comprising a plurality of taps including a first tap having a first helical thread cutting ridge forming a first thread cutting thread and at least a second tap having a second helical thread cutting ridge forming a second thread cutting thread, each of said cutting threads having crest and root diameters at least one of which is smaller in said first tap than in said second tap, said cutting threads in all taps of the set having the same thread pitch independently of the differences between said diameters and said differences being sufficiently small to ensure that a female thread cut by said first tap is not damaged when such female thread is being enlarged by said second tap of the set.
A set of externally threaded fasteners each having a thread crest diameter and a thread root diameter, said set comprising a first fastener having a first helical thread ridge forming a first thread and at least one second fastener having a second helical thread ridge forming a second thread, said first and second threads having at least one of said thread crest and root diameters that increase in at least one incremental step, said threads of all fasteners in the set having the same constant thread pitch independently of said incrementally increasing step in said at least one of said thread crest and root diameters.
The combination of a first set of thread cutting taps and a corresponding second set of externally threaded fasteners, said first set comprising a plurality of thead cutting taps including at least a first tap having a first helical thread cutting ridge forming a first cutting thread, and a second tap having a second helical thread cutting ridge forming a second cutting thread, said cutting threads having crest diameters that increase in incremental steps from tap to tap starting with the first tap, said cutting threads of all taps in said first set having the same constant thread pitch independently of said incrementally increasing steps in said crest diameters and an increase in said incremental steps of said crest diameters in said taps is such that a female threading cut by a tap of a lower number in said first set is not damaged when such female threading is widened or repaired by a tap having a next higher number in said first set, said second set of externally threaded fasteners comprising a plurality of fasteners including at least a first fastener having a first helical thread ridge forming a first thread and a second fastener having a second helical thread ridge forming a second thread, said threads having thread crest diameters that increase in incremental steps from fastener to fastener in said second set starting with said first fastener, said threads of all fasteners in said second set having the same constant thread pitch independently of said incrementally increasing steps in said thread crest diameters of the fasteners and taps of both sets, each tap number in said first set corresponding to a certain fastener number in said second set in respect of the crest diameter so that the corresponding fastener number of said second set is a tight fit when engaging a female threading cut by the corresponding tap number of said first set, and a replacement of a fastener of lower number in said second set by a fastener with a next higher number in said second set results in a tight fit in a female threading without damage to such female threading to be engaged by said fastener with said next higher number in said second set for a tight fit.
Dependencies are inferred from the claim text.