US-12620114-B2 - Image processing device and machine tool

US12620114B2US 12620114 B2US12620114 B2US 12620114B2US-12620114-B2

Abstract

An image processing device includes: a receiving unit that receives an image of a tool from a camera of a machine tool; a measurement unit that measures a first coordinate, which is a position of a first point on a tool or a tool holding unit that holds the tool, in an image captured when the tool and the camera move a first distance relative to each other and measures a second coordinate, which is a position of a second point on the tool or the tool holding unit, in an image captured when the tool and the camera move a second distance relative to each other; and a tool length calculation unit that calculates the length of the tool based on the first coordinate, the second coordinate, the first distance, and the second distance.

Inventors

Junichi Kubota

Assignees

DMG MORI CO., LTD.

Dates

Publication Date: 20260505
Application Date: 20230814
Priority Date: 20210215

Claims (4)

1 . An image processing device, comprising: a processor including a receiving unit, a measurement unit, and a tool length calculation unit; a memory storing various programs and supplying processing instructions, wherein the receiving unit receives an image of a tool from a camera of a machine tool; the measurement unit measures a first coordinate, which is a position of a first point on a tool or a tool holding unit that holds the tool, in an image captured when the tool and the camera are relatively moved by a first distance from a reference point at which the tool and the camera are separated by a predetermined distance from each other and measures a second coordinate, which is a position of a second point on the tool or the tool holding unit, in an image captured when the tool and the camera are relatively moved by a second distance from the reference point; and the tool length calculation unit calculates a length of the tool based on the first coordinate, the second coordinate, and a basic difference which is a difference between the first distance and the second distance, thereby taking into account a stretching effect of a base of the machine tool caused by heat during processing, wherein the first point is an end face position of the tool holding unit, and the second point is a tip position of the tool.
2 . The image processing device according to claim 1 , wherein the tool length calculation unit calculates the length of the tool by adding a first difference, which is a difference between a reference position in an image-capturing area and the first coordinate, to the basic difference.
3 . The image processing device as claimed in claim 2 , wherein the tool length calculation unit further calculates the length of the tool by adding the first difference to the basic difference and further adding a second difference, which is the difference between the reference position in the image-capturing area and the second coordinate.
4 . A machine tool, comprising: a camera that captures an image for measuring a first coordinate and a second coordinate and for calculating a length of a tool based on the first coordinate, the second coordinate, and a basic difference which is a difference between a first distance and a second distance, thereby taking into account a stretching effect of a base of the machine tool caused by heat during processing; a tool holding unit that holds the tool; a memory that stores various programs and supplying processing instructions; and a processor that moves the tool holding unit to move the tool and the camera by the first or second distance relative to each other, wherein the camera captures a first image when the tool and the camera are relatively moved by the first distance from a reference point at which the tool and the camera are separated by a predetermined distance from each other and captures a second image when the tool and the camera are relatively moved by the second distance from the reference point, the first image includes the first coordinate, which is the position of the first point on the tool or the tool holding unit that holds the tool, the second image includes the second coordinate, which is the position of the second point on the tool or the tool holding unit that holds the tool, and wherein the first point is an end face position of the tool holding unit, and the second point is a tip position of the tool.

Description

CROSS REFERENCE TO RELATED APPLICATIONS This application is a continuation application of International Application No. PCT/JP2022/000498, filed on Jan. 11, 2022, which claims priority to and the benefit of Japanese Patent Application No. 2021-021386, filed on Feb. 15, 2021. The contents of these applications are incorporated herein by reference in their entirety. BACKGROUND OF INVENTION 1. Field This invention relates to tool inspection technology in machine tools. 2. Description of Related Art Examples of machine tools include devices for cutting a workpiece into a desired shape and devices for depositing metal powder or the like to make a workpiece. Examples of machine tools for cutting include a turning center that machines a workpiece by applying a tool for cutting to the workpiece that is being turned, a machining center that machines a workpiece by applying a turning tool to the workpiece, and a multitasking machine including these functions in combination. A tools is fixed to a tool holding unit such as a spindle or tool rest. A machine tool machines a workpiece by changing tools and moving the tool holding unit according to a machining program provided in advance. The cutting edges of the tools gradually wear due to friction with the workpiece. The user needs to determine the tool life by checking the tool length as necessary (see Patent Literatures 1 and 2). RELATED ART LIST Patent Literature 1: JP H10-143216 APatent Literature 2: JP 2017-021472 A As an example of a method for measuring tool length, e.g., a camera is fixed, and a tool is moved under the camera by moving the tool holding unit a certain distance from the origin position. The tool length is then calculated based on the difference between the center of the image-capturing area and the tool tip. This is because when the tool length is long, the tool tip is detected at a deep position in the image-capturing area, and when the tool length is short, the tool tip is detected at a shallow position in the image-capturing area. However, the distance from the origin position to the camera increases due to the heat generated by the machine tool during machining. Since the distance from the origin position to the camera is unstable, the tool length measurement results of the above method may be affected by heat. SUMMARY An image processing device in an aspect of the present invention includes: a receiving unit that receives an image of a tool from a camera of a machine tool; a measurement unit that measures a first coordinate, which is a position of a first point on a tool or a tool holding unit that holds the tool, in an image captured when the tool and the camera move a first distance relative to each other and measures a second coordinate, which is a position of a second point on the tool or the tool holding unit, in an image captured when the tool and the camera move a second distance relative to each other; and a tool length calculation unit that calculates the length of the tool based on the first coordinate, the second coordinate, the first distance, and the second distance. The “tool holding unit” may be a spindle, turret, or tool rest. In any case, the tool holding unit can be any member that holds a tool in a machine tool. An image processing device in another aspect of the invention includes: a receiving unit that receives an image of a tool from a camera of a machine tool; a measurement unit that measures a position coordinate of a predetermined position of a tool or a tool holding unit that holds a tool in an image captured when the tool and the camera move a predetermined distance relative to each other; and a thermal displacement calculation unit that calculates the thermal displacement amount of the machine tool based on the difference between a reference position in an image-capturing area and the measured position coordinate. An image processing device in another aspect of the invention includes: a receiving unit that receives an image of a tool from a camera of a machine tool; a measurement unit that measures a first coordinate, which is a position of a first point on a reference tool or a tool holding unit, in an image captured when the reference tool and the camera move a first distance relative to each other and calculates a first difference, which is a difference between the reference position and the first coordinate in the image-capturing area, and measures a second coordinate, which is a position of a second point on the tool or the tool holding unit, in an image captured when the reference tool and the camera move a second distance relative to each other and calculates a second difference, which is the difference between the reference position and the second coordinate in the image-capturing area; a holder length calculation unit that calculates the holder length in the tool holding unit based on the first difference and the second difference; and a tool length calculation unit that calculates the length of an inspecti