The present invention discloses a method of constructing a high-frequency vibratory stress relief device for eliminating residual stress of a small work-piece. The method comprises the following steps: fabricating a high-frequency vibration energy amplification device; fabricating a clamping device; mounting the high-frequency vibration energy amplification device; obtaining surface residual stress distribution on the small work-piece by means of X-ray diffraction; establishing a finite element model of the small work-piece; determining a target frequency f, determining the structural dimensions of the high-frequency vibration energy amplification device; analyzing the displacement mode to obtain loci of the vibration node lines and number of the vibration node lines; clamping the small work-piece; attaching strain gauges; connecting all devices. The present invention has the advantage of being able to increase the vibration energy acting on the small work-piece to achieve a better effect of high-frequency vibratory stress relief.

A turning and thread-rolling machine with a pre-compression device includes a fixing base on which the pre-compression device, a fixing mechanism, a guiding base, a processing mechanism assembly, and a control unit are provided, wherein the pre-compression device includes a carrier and at least two cold-rolling heads in order to form by compression a pre-compressed annular groove in a portion of an unprocessed rebar that is adjacent to one end thereof, and, under the control of the control unit, the fixing mechanism clamps the rebar, and the guiding base displaces the processing mechanism assembly to the end of the rebar to perform turning and thread rolling sequentially, thereby processing the end of the rebar into a coupling end. The pre-compressed annular groove facilitates on-site inspection of thread quality and prevents the thread-rolling dies in the processing mechanism assembly from contact with, and hence damage by, the ribs on the rebar.

A turning and thread-rolling machine with a pre-compression device includes a fixing base on which the pre-compression device, a fixing mechanism, a guiding base, a processing mechanism assembly, and a control unit are provided, wherein the pre-compression device includes a carrier and at least two cold-rolling heads in order to form by compression a pre-compressed annular groove in a portion of an unprocessed rebar that is adjacent to one end thereof, and, under the control of the control unit, the fixing mechanism clamps the rebar, and the guiding base displaces the processing mechanism assembly to the end of the rebar to perform turning and thread rolling sequentially, thereby processing the end of the rebar into a coupling end. The pre-compressed annular groove facilitates on-site inspection of thread quality and prevents the thread-rolling dies in the processing mechanism assembly from contact with, and hence damage by, the ribs on the rebar.

The invention relates to methods of stabilizing bone implants, comprising inserting a self-tapping implant having at least two helical grooves running in opposite directions around the implant.

A method of machining a screw is provided that is capable of preventing formation of a protruding section at a thread tip section. A thread is formed by cutting on a cylindrical body, and a surface of the thread is plastically deformed by rolling. Because of the cutting, a width between-side surfaces of a thread tip section is in a narrowed state as compared to a normal width. This width is narrowed toward a tip of the thread while a thread body section has a width expanded as compared to a normal width. Consequently, the side surfaces are formed to bulge by an excess thickness portion as compared to normal side surfaces. The rolling plastically deforms both side surfaces to cause the excess thickness portion to plastically flow toward the side surfaces.

A method of machining a screw is provided that is capable of preventing formation of a protruding section at a thread tip section. A thread is formed by cutting on a cylindrical body, and a surface of the thread is plastically deformed by rolling. Because of the cutting, a width between-side surfaces of a thread tip section is in a narrowed state as compared to a normal width. This width is narrowed toward a tip of the thread while a thread body section has a width expanded as compared to a normal width. Consequently, the side surfaces are formed to bulge by an excess thickness portion as compared to normal side surfaces. The rolling plastically deforms both side surfaces to cause the excess thickness portion to plastically flow toward the side surfaces.

A machine tool and a control device for the machine tool for shortening the machining time of a workpiece in a case where the relative and reciprocal vibration of workpiece holder and tool post in the radial direction of the workpiece is stopped during a period from an initial point until when the workpiece and the cutting tool come into contact with each other is provided. In the machine tool, when threading the workpiece to form a threaded portion on the workpiece by relatively moving the workpiece and the cutting tool in the feed direction while relatively rotating the workpiece and the cutting tool 130 to perform multiple times of cutting processes along the same cutting path in a predetermined spiral form, the cutting tool is brought closer toward the workpiece in the feed direction from a predetermined initial point at which the workpiece and the cutting tool are separated from each other, the workpiece and the cutting tool come into contact with each other, and the threading is started with the contact. During the period from the initial point until when the workpiece and the cutting tool come into contact with each other, a controller stops the vibration of the cutting tool, and, in continuous cutting processes in the multiple times of cutting processes in the threading, the control means sets a phase position of the tool post in the vibration direction and stops the reciprocal vibration so that, when the workpiece and the cutting tool come into contact with each other, each of the continuous cutting processes has a predetermined phase in the reciprocal vibration relative to a rotation phase of the workpiece at the start of the threading.

A machine tool and a control device for the machine tool for shortening the machining time of a workpiece in a case where the relative and reciprocal vibration of workpiece holder and tool post in the radial direction of the workpiece is stopped during a period from an initial point until when the workpiece and the cutting tool come into contact with each other is provided. In the machine tool, when threading the workpiece to form a threaded portion on the workpiece by relatively moving the workpiece and the cutting tool in the feed direction while relatively rotating the workpiece and the cutting tool 130 to perform multiple times of cutting processes along the same cutting path in a predetermined spiral form, the cutting tool is brought closer toward the workpiece in the feed direction from a predetermined initial point at which the workpiece and the cutting tool are separated from each other, the workpiece and the cutting tool come into contact with each other, and the threading is started with the contact. During the period from the initial point until when the workpiece and the cutting tool come into contact with each other, a controller stops the vibration of the cutting tool, and, in continuous cutting processes in the multiple times of cutting processes in the threading, the control means sets a phase position of the tool post in the vibration direction and stops the reciprocal vibration so that, when the workpiece and the cutting tool come into contact with each other, each of the continuous cutting processes has a predetermined phase in the reciprocal vibration relative to a rotation phase of the workpiece at the start of the threading.

The removal starting position (8S1) of a first removal process and the four removal starting positions (8S21-8S24) in a second removal process are established on an imaginary circle (7I) with a prescribed radius (R) that is inscribed in the apex (7C) of an incomplete thread part (7a). In each removal process, the tip of the screw thread cutting tool shaves off the apex (7C) of the incomplete thread part (7a) into respective recesses, contacting the imaginary inscribed circle (7I) from the outside (above). The multiple cutting surfaces of the apex (7C) are formed in parallel helices (that is, as mutually adjacent helical recesses) from the starting position to the ending position of the incomplete thread part. Points and burrs in the incomplete thread part can thereby be eliminated or reduced without loss of the ability to screw together with a partner threaded fastener (threaded portion).

The removal starting position (8S1) of a first removal process and the four removal starting positions (8S21-8S24) in a second removal process are established on an imaginary circle (7I) with a prescribed radius (R) that is inscribed in the apex (7C) of an incomplete thread part (7a). In each removal process, the tip of the screw thread cutting tool shaves off the apex (7C) of the incomplete thread part (7a) into respective recesses, contacting the imaginary inscribed circle (7I) from the outside (above). The multiple cutting surfaces of the apex (7C) are formed in parallel helices (that is, as mutually adjacent helical recesses) from the starting position to the ending position of the incomplete thread part. Points and burrs in the incomplete thread part can thereby be eliminated or reduced without loss of the ability to screw together with a partner threaded fastener (threaded portion).