Thread cutting tap and a method of its manufacture
AssigneeSandvik Intellectual Property AB
InventorsMarkus Oknestam, Stefan Zivkovic
Life of this patent
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Abstract
A thread cutting tap having a threaded portion for cutting out a thread in a wall of a workpiece opening into which the threaded portion is to be introduced. The threaded portion is provided with at least two cutting edges extending in a circumferential direction of the body. Each cutting edge is an integral peripheral part of a flank portion extending substantially radially from the body. The flank portions define between one another a chip removal flute extending in the longitudinal extension of the body for removal of chips. At least one of the flank portions has a side wall divided into a pair of elongated concave surfaces separated by an elongated ridge constituting a chip-breaking member. The chip removal flutes are at least partly helically shaped.
Claims22
A thread cutting tap having an elongated body, the body comprising at a first end thereof a connector portion adapted to be connected to a tool and at a second end thereof a threaded portion for cutting a thread in a surface of a workpiece, said threaded portion being provided with at least two cutting edges extending in the circumferential direction of said body, each of said cutting edges comprising an integral peripheral part of a flank portion of said body and extending substantially radially from the longitudinal extension of said body, said flank portions defining between themselves at least one chip removal flute extending generally in the longitudinal extension of said body for removal of chips, at least one of said flank portions having a side wall forming part of said at least one flute, said at least one flute provided with a chip-breaking member, wherein at least a portion of said at least one flute being helically shaped, and wherein at least a portion of the chip breaking member is located in the portion of the at least one flute that is helically shaped, wherein said side wall, as viewed in a cross section oriented perpendicularly to a longitudinal axis of said elongated body, is divided into a pair of elongated concave surfaces separated by an elongated ridge constituting the chip-breaking member, and wherein the elongated ridge on a trailing, non-cutting surface of the flute comprises an edge formed by the immediate interconnection of said concave surfaces.
A method of manufacturing a thread cutting tap comprising the steps of:
- A) selecting an elongated blank having an elongated body with a first end portion and a second end portion;
- B) forming in the second end portion of said blank at least one thread having a cutting edge at its circumferential periphery;
- C) forming at least two chip removal flutes traversing said thread, such that a flank portion having a side wall is formed between two neighboring flutes, at least a portion of each flute being of helical shape;
- and
- D) forming in a side wall of each flank portion at least one chip-breaking members
- wherein step D comprises forming said chip-breaking member as an elongated ridge separating a pair of elongated concave surfaces of the side-wall, and
- wherein said ridge is formed as an edge on a trailing, non-cutting surface of the flute.
Dependencies are inferred from the claim text.