US 12,214,434 B2Granted

Machine tool and control device for machine tool

AssigneesCitizen Watch Co., Ltd., Citizen Machinery Co., Ltd.

InventorKazuhiko Sannomiya

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Abstract

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.

Claims2

Dependent claims

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.

8 more elements

A control device for a machine tool provided with:

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;
and
rotating means for relatively rotating at least one of the workpiece and the cutting tool,
the control device controlling operations of the feeding means, the vibration means and the rotating means,
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.

8 more elements

Dependencies are inferred from the claim text.

Facts

Application: 17/437,284Filed 22 May 2020
Priority: JP 2019-09991829 May 2019
Published: US 2022/0161339 A126 May 2022
Granted: 4 Feb 2025
Term ends: Not estimatedThe source records don’t support an estimate.

Classification13 codes

B23G 1/02
Thread cutting; Automatic machines specially designed therefor: on an external or internal cylindrical or conical surface, e.g. on recesses
G05B 19/404
Numerical control [NC], i.e. automatically operating machines, in particular machine tools, e.g. in a manufacturing environment, so as to…
B23B 1/00
Methods for turning or working essentially requiring the use of turning-machines
B23Q 15/013
While the tool acts upon the workpiece: control or regulation of feed movement