Welding machine and control method therefor

• US 10,191,470 B2
• Filed: 01/15/2015
• Issued: 01/29/2019
• Est. Priority Date: 05/09/2014
• Status: Active Grant

• Current Assignee: Amada Holdings Co Ltd (Amada Company Limited)
• Original Assignee: Amada Holdings Co Ltd (Amada Company Limited)
• Inventors: Inoue, Hiroki
• Primary Examiner(s): Lee, Adam
• Application Number:
  US15/126,780
• Publication Number:
  US 20170123403A1
• Time in Patent Office: 1,475 Days
• CPC Class Codes: B23K 26/02 Positioning or observing the workpiece, e.g. with respect to the point of impact; Aligning, aiming or focusing the laser beam
• CPC Class Codes: B23K 26/032 using optical means
• CPC Class Codes: B23K 26/04 Automatically aligning, aiming or focusing the laser beam, e.g. using the back-scattered light
• CPC Class Codes: B23K 26/042 Automatically aligning the laser beam
• CPC Class Codes: B23K 26/21 by welding
• CPC Class Codes: B25J 9/1684 Tracking a line or surface by means of sensors
• CPC Class Codes: G05B 19/402 characterised by control arrangements for positioning, e.g. centring a tool relative to a hole in the workpiece, additional detection means to correct position G05B19/19 takes precedence
• CPC Class Codes: G05B 19/4083 Adapting programme, configuration
• CPC Class Codes: G05B 2219/37563 Ccd, tv camera
• CPC Class Codes: G05B 2219/45104 Lasrobot, welding robot
• CPC Class Codes: G05B 2219/45138 Laser welding
• CPC Class Codes: G05B 2219/4705 Detect edge during machining, welding, sewing
• CPC Class Codes: G06T 2207/10004 Still image; Photographic image
• CPC Class Codes: G06T 2207/30136 Metal
• CPC Class Codes: G06T 2207/30164 Workpiece; Machine component
• CPC Class Codes: G06T 7/0004 Industrial image inspection
• CPC Class Codes: G06T 7/13 Edge detection

Abstract

An edge extraction unit extracts an edge image from a photographed image obtained by photographing a product with a camera. A constant edge acquisition unit acquires, as a constant edge image, an edge image in a constant surface where a positional deviation does not occur with respect to a welding point set by a processing program, the acquired image belonging to the extracted edge image. A correction amount acquisition unit performs pattern-matching between a master constant edge image and a workpiece edge image, which are acquired by the constant edge acquisition unit, and acquires a deviation amount between both thereof as a correction amount with respect to the welding point. A processing program correction unit corrects the welding point by the correction amount, and generates a corrected processing program for welding the workpiece. A welding robot welds the workpiece based on the corrected processing program.

Claims

1. A welding machine comprising:

a camera that photographs a master product to obtain a photographed master image and that photographs a workpiece to obtain a photographed workpiece image;

an operation unit by which an operator indicates coordinates on the photographed master image;

a computer that

performs operations using the photographed master image, comprising;

receiving first coordinates on the photographed master image, the first coordinates being indicated on a master constant surface by the operation unit, the master constant surface being a region of the master product determined to lack a positional deviation with respect to a master welding point on the master product, the master welding point being a welding point set by a processing program for welding the master product;

extracting a master edge image of the master product from the photographed master image;

acquiring a master constant surface region of the master constant surface including the first coordinates; and

acquiring a master constant edge image based on the master edge image and the master constant surface region, the master constant edge image including a first edge image of the master constant surface region; and

performs operations using the photographed workpiece image, comprising;

extracting a workpiece edge image of the workpiece from the photographed workpiece image;

acquiring a workpiece constant surface region including second coordinates of a position on the photographed workpiece image, the second coordinates being obtained based on the first coordinates;

acquiring a workpiece constant edge image based on the workpiece edge image and the workpiece constant surface region, the workpiece constant edge image including a second edge image of the workpiece constant surface region;

performing pattern-matching between the master constant edge image and the workpiece constant edge image so as to match the first edge image and the second edge image to acquire a first deviation amount between the master constant edge image and the workpiece constant edge image as a correction amount for a workpiece welding point, wherein the workpiece welding point is set by the processing program and is a point at which the workpiece is welded; and

correcting the workpiece welding point by the correction amount to generate a corrected processing program for welding the workpiece; and

a welding robot that welds the workpiece based on the corrected processing program.

2. The welding machine according to claim 1, wherein the computer further

performs operations using the photographed master image, comprising:

estimating the master constant surface region based on the master edge image and the first coordinates to acquire the master constant surface region; and

acquiring the first edge image in the master constant surface region; and

performs operations using the photographed workpiece image, comprising;

estimating the workpiece constant surface region based on the workpiece edge image and the second coordinates to acquire the workpiece constant surface region; and

acquiring the second edge image in the workpiece constant surface region.

3. The welding machine according to claim 2, wherein the computer further

performs operations using the photographed master image and the photographed workpiece image, comprising:

aligning the master edge image and the workpiece edge image with each other to acquire a second deviation amount between the master edge image and the workpiece edge image; and

acquiring the second coordinates by shifting the first coordinates by the second deviation amount.

4. A control method for a welding machine, the control method comprising:

defining a product as a master, which is taken as a reference among a plurality of products;

defining another product among the plurality of products other than the master as a workpiece;

acquiring a photographed master image by photographing, with a camera, a region including a master welding point and an edge on the master, the master welding point being a welding point set by a processing program for welding the master;

receiving first coordinates of a position on the photographed master image, the first coordinates being indicated on a master constant surface by an operation unit, the master constant surface being a region of the master determined to lack a positional deviation with respect to the master welding point;

extracting a master edge image of the master from the photographed master image;

acquiring a master constant surface region of the master constant surface including the first coordinates;

acquiring a master constant edge image based on the master edge image and the master constant surface region, the master constant edge image including a first edge image of the master constant surface region;

acquiring a photographed workpiece image by photographing, with the camera, a region including a workpiece welding point and an edge on the workpiece, the workpiece welding point being set by the processing program for welding the workpiece together;

extracting a workpiece edge image of the workpiece from the photographed workpiece image;

acquiring a workpiece constant surface region including second coordinates of a position on the photographed workpiece image, the second coordinates being obtained based on the first coordinates;

acquiring a workpiece constant edge image based on the workpiece edge image and the workpiece constant surface region, the workpiece constant edge image including a second edge image of the workpiece constant surface region;

performing pattern-matching between the master constant edge image and the workpiece constant edge image so as to match the first edge image and the second edge image to acquire a first deviation amount between the master constant edge image and the workpiece constant edge image as a correction amount for the workpiece welding point;

correcting the workpiece welding point by the correction amount to generate a corrected processing program for welding the workpiece; and

controlling a welding robot to weld the workpiece based on the corrected processing program.

5. The control method for a welding machine according to claim 4, further comprising:

estimating the master constant surface region based on the master edge image and the first coordinates to acquire the master constant surface region;

estimating the workpiece constant surface region based on the workpiece edge image and the second coordinates to acquire the workpiece constant surface region;

acquiring the first edge image in the master constant surface region; and

acquiring the second edge image in the workpiece constant surface region.

6. The control method for a welding machine according to claim 4, wherein the position on the photographed master image of the first coordinates is manually input to the welding machine by an operator.

7. The control method for a welding machine according to claim 4, further comprising:

aligning the master edge image and the workpiece edge image with each other to acquire a second deviation amount between the master edge image and the workpiece edge image; and

determining the second coordinates by shifting the first coordinates by the second deviation amount.