US 4,752,159 AGranted

Tapered thread forming apparatus and method

AssigneeHowlett Machine Works

InventorJames W. Howlett

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Abstract

A thread cutting apparatus and method are disclosed for the formation of tapered threads on the end of an elongated reinforcing bar of the type used in concrete structures. The apparatus includes a cutting head assembly having tool holder arms that are cantilevered outwardly from a face or barrier surface to effect cutting of the threads outwardly of the barrier so as to protect the guideways and cutting displacement structure control structure from chips and debris. The apparatus includes positive lead control for the thread cutting chasers, a rigid clamping structure for the bar and a fluid control assembly. The fluid control assembly is capable of positioning the cutting head and housing for one or a multiple number of frusto-conical cuts of predetermined depth to permit the simultaneous formation of threads and removal of material from the reinforcing bar end.

Claims16

Dependent claims

A thread cutting apparatus for forming a tapered thread on a bar end of an elongated reinforcing bar having a longitudinal axis, said apparatus including bar clamping means formed to releasably hold said bar for formation of said thread on said bar end;

a cutting head assembly mounted proximate said clamping means for rotation about a rotational axis substantially aligned with said longitudinal axis, said head assembly including tool holder means and thread cutting tool means mounted to said tool holder means for rotation with said head assembly, and drive means coupled to said head assembly for advancemnt of said tool holder means and for simultaneous rotation of said head assembly to cause said tool means to engage and cut a thread on said bar end at an angle to said longitudinal axis;
wherein the improvement in said thread cutting apparatus comprises:
said head assembly is mounted proximate said bar end in axially spaced relation thereto and includes a face portion facing said bar end, and guide means extending at said angle in said head assembly away from said face portion;
said tool holder means being movably mounted in said guide means and cantilevered outwardly at said angle from said face portion toward said bar end;
said face portion and said tool holder means being cooperatively formed to prevent metal chips from penetrating between said face portion and said guide means during cutting of said bar end;
said thread cutting apparatus further being formed to prevent metal chips from migrating around said head assembly to said guide means;
and
said guide means guiding cantilevered displacement of said tool holder means away from said face portion along said longitudinal axis at said angle thereto to effect cutting of said thread.

5 more elements

Dependencies are inferred from the claim text.