A machining device threads a workpiece by relatively rotating the workpiece and a multi-blade tool and relatively moving them along a feed direction to perform cutting processes in the radial direction of the workpiece along the same cutting path in a predetermined spiral form. A controller performs a groove machining to form a threaded portion with vibration in the radial direction of the workpiece and a finish machining to form the threaded portion by bringing the multi-blade tool into contact with the grooved portion of the workpiece. The multi-blade tool has a first cutting blade and a second cutting blade arranged side by side along the feed direction. The controller sets amplitude of a vibration waveform to a value at which a cutting edge of the second cutting blade does not come into contact with the screw bottom surface of the workpiece in the finish machining.

A method of manufacturing a threaded hole in a workpiece includes providing the workpiece having a region with a hole. The method also includes cutting a threading for the hole. Furthermore, the method includes, independent of cutting the threading, densifying the region proximate the hole to reduce material porosity in the region.

Disclosed are threading device and threading method, including a turning step for threading a rotating workpiece with a predetermined cutting depth, by relatively moving a tool in the axial direction of the workpiece and then rounding-up the workpiece obliquely by relatively moving the tool in the axial direction and radially outward. The workpiece is subjected to the threading process by repeatedly carrying out the turning step while sequentially shifting the axial position for starting the rounding-up of the workpiece relative to an axial position where the rounding-up of the workpiece has been started in a previous turning step.

The invention relates to a method of making a thread or tap on a cylindrical, conical or frustoconical piece to be machined.

According to the invention, this method comprises the steps of: a) driving in rotation the piece to be machined in one direction), b) carrying out a relative displacement of a first cutting edge of a tool relative to the piece to be machined until this first cutting edge is flush with the surface to be threaded of the workpiece at the beginning of the section to be threaded, c) carrying out a relative displacement of the tool relative to the piece to be machined so that the first cutting edge machines the piece to be machined, d) carrying out a relative displacement of the tool along the longitudinal axis of the piece to be machined, in one direction until the end of the section to be threaded, e) moving away, by a relative displacement, the first cutting edge of the tool from the piece to be machined,
and it has the particularity of further comprising the steps of: f) reversing the rotation of the piece to be machined to drive this piece in rotation in the direction opposite to the direction, while positioning or not the second cutting edge, g) moving, by relative displacement, a second cutting edge towards the piece to be machined until this second cutting edge penetrates the thread pitch, h) carrying out a relative displacement of the second cutting edge relative to the workpiece so that it continues the machining of the thread in the piece to be machined, i) carrying out a relative displacement of the second cutting edge in a direction opposite to the direction, until the beginning of the section to be threaded, j) moving, by a relative displacement, the second cutting edge away from the workpiece to be machined, k) reversing the rotation of the piece to be machined, while positioning or not the first cutting edge then l) repeating steps b) to k), while continuing the machining of the thread, until the thread reaches its final dimensions, while positioning the first cutting edge in step b) in such a way that it penetrates the thread pitch already machined.

In a method for creating a through-thread, thread creation means is moved in a screw-in movement in an axial forward direction (VR) through a workpiece from a first workpiece side to a second workpiece side opposite the first workpiece side such that the end face projects out of the workpiece, wherein the thread creation means is moved through the workpiece, in particular along a first line which is a helical line, wherein then, to create at least one countersink, the thread creation means is moved in a countersinking movement, in particular along a second line that differs from the first line, and wherein, for subsequent withdrawal, the thread creation means is moved back through the workpiece in a screw-out movement in the axial backward direction (RR), in particular at least substantially along the first line.

Various methods are described for forming threads in a workpiece, and particularly for controlling and/or monitoring threading of workpieces. Also described are tools and a system used in performing the methods.

The invention relates to methods for producing a thread with a predetermined thread pitch in a workpiece.

A tap phase detection method includes: acquiring a relation between a rotation angle and an existence of a screw thread by measuring a position of the screw thread of a tap with a sensor from a direction intersecting with an axial direction of the tap while rotating the tap; and detecting a phase of the tap based on the acquired relation between the rotation angle and the existence of the screw thread.

A threading tool includes: a tool main body; and a cutting edge portion, which is provided on a tip portion of the tool main body and has a rake face and a flank face. The cutting edge portion includes: a primary cutting edge extending in a tooth width direction of the cutting edge portion; two corner edges, one and other of which are provided on one and other of both ends of the primary cutting edge, respectively, and are in a convex curve shape; and two secondary cutting edges, one and other of which extend from the one and the other of the two corner edges to a rear end side of the cutting edge portion, respectively. Two secondary cutting edges are shorter than the primary cutting edge. At least one of the two secondary edges is slanted to a direction intersecting the primary cutting edge in an obtuse angle.

Various methods are described for forming threads in a workpiece, and particularly for controlling and/or monitoring threading of workpieces. Also described are tools and a system used in performing the methods.