US 12,214,434 B2
Machine tool and control device for machine tool
Kazuhiko Sannomiya, Kitasaku-gun (JP)
Assigned to CITIZEN WATCH CO., LTD., Tokyo (JP); and CITIZEN MACHINERY CO., LTD., Nagano (JP)
Appl. No. 17/437,284
Filed by CITIZEN WATCH CO., LTD., Tokyo (JP); and CITIZEN MACHINERY CO., LTD., Nagano (JP)
PCT Filed May 22, 2020, PCT No. PCT/JP2020/020409
§ 371(c)(1), (2) Date Sep. 8, 2021,
PCT Pub. No. WO2020/241524, PCT Pub. Date Dec. 3, 2020.
Claims priority of application No. 2019-099918 (JP), filed on May 29, 2019.
Prior Publication US 2022/0161339 A1, May 26, 2022
Int. Cl. B23G 1/02 (2006.01); B23Q 15/013 (2006.01); G05B 19/4093 (2006.01); B23B 25/02 (2006.01); B23G 1/04 (2006.01)
CPC B23G 1/02 (2013.01) [B23Q 15/013 (2013.01); B23B 25/02 (2013.01); B23G 1/04 (2013.01); G05B 2219/37435 (2013.01)] 2 Claims
OG exemplary drawing
 
1. A machine tool comprising:
workpiece holding means for holding a workpiece;
a tool post to hold a cutting tool for cutting the workpiece;
feeding means for feeding the cutting tool in a predetermined feed direction toward the workpiece by a relative movement of the workpiece holding means and the tool post;
vibration means for relatively and reciprocally vibrating at least one of the workpiece holding means and the tool post in a radial direction of the workpiece;
rotating means for relatively rotating at least one of the workpiece and the cutting tool; and
control means for controlling operations of the feeding means, the vibration means and the rotating means, and
in threading the workpiece to form a threaded portion on the workpiece by performing multiple times of cutting processes that are performed by relatively moving the at least one of the workpiece and the cutting tool in the feed direction along the same cutting path in a predetermined spiral form while relatively rotating the at least one of the workpiece and the cutting tool and by cutting the workpiece with the cutting tool, in each of the cutting processes, the cutting tool being brought closer to a machining start point, which is set at a distance away from an end face of the workpiece, the distance being determined by multiplying a pitch of the threaded portion by a predetermined number of times, from a predetermined initial point, which is diagonally above the end face of the workpiece and at which the workpiece and the cutting tool are separated from each other, and the cutting tool being brought into contact with the workpiece by feeding the cutting tool from the machining start point in the feed direction to start the cutting process with the contact, wherein
in each of the cutting process, phase in reciprocal vibration of the cutting tool when the cutting tool reaches the machining start point synchronizes with rotation phase of the relative rotation to form a threaded portion on the workpiece, wherein
the control means stops reciprocal vibration of the cutting tool when the cutting tool moves from the initial point to the machining start point in each of the cutting processes, and wherein
the control means performs the synchronization before the cutting tool reaches the machining start point in each of the cutting processes.