Seam welding apparatus, seam welding method, robot control device, and robot control method

Patent metadata

Field	Value
Publication number	US-10821540-B2
Application number	US-201514741465-A
Country	US
Kind code	B2
Filing date	Jun 17, 2015
Priority date	Dec 18, 2012
Publication date	Nov 3, 2020
Grant date	Nov 3, 2020

Abstract

The seam welding apparatus includes a pair of rotating electrodes, an electrode supporting frame, a distance measuring means, and a controller. The electrode supporting frame supports the pair of rotating electrodes. The distance measuring means is provided on the electrode supporting frame and measures a distance to an edge of the steel plate. The controller controls the robot to adjust a running direction of the rotating electrodes so that a deviation comes into zero when a distance actually measured by the distance measuring means deviates from a predetermined distance. Thereby, it is accomplished that the seam welding apparatus is downsized as well as uninfluenced by the surface state and/or shape of workpiece (steel plate).

First claim

The invention claimed is:

1. A seam welding apparatus that performs seam welding on layered steel plates, the seam welding apparatus comprising:
an articulated robot capable of setting a predetermined tolerance for a joint; and
a welding device attached to the robot and revolvable about a revolving axis of the robot,
the welding device comprising:
a pair of rotation electrodes for seam-welding the layered steel plates while applying pressure, the pair of rotation electrodes being rotatably supported by the welding device about respective rotation axes orthogonal to the revolving axis;
an electrode supporting frame that supports the rotating electrodes;
an optical distance measuring device provided on the electrode supporting frame, the optical distance measuring device including:
a laser emission part disposed to face an edge of one of the layered steel plates, the laser emission part being configured to emit light toward the edge;
a light position detecting device configured to receive the light emitted from the laser emission part that reflects from the edge so as to detect a position of the received light reflected from the edge, the light position detecting device comprising a plurality of light receiving elements that are arranged in a row in an extending direction of the edge and receive different reflected lights corresponding to positions at which the light reflects from the edge of one of the layered steel plates;
a light projecting lens; and
a light receiving lens,
wherein the laser emission part, the light position detecting device, the light projecting lens, and the light receiving lens are provided at fixed positional relationships with respect to each other, and
the optical distance measuring device is configured to geometrically measure, based on which light receiving element of the plurality of light receiving elements of the light position detecting device receives the different reflected lights, a distance from the optical distance measuring device to the edge in a direction parallel to the rotation axes of the pair of rotation electrodes; and

a controller configured to:
set a target position of the welding device to set a target distance from the optical distance measuring device to the edge when the welding device is in the target position;
calculate a deviation of the distance measured by the optical distance measuring device from the target distance while the pair of rotation electrodes is running on the layered steel plates to perform seam welding; and
control the robot to adjust a running direction of the rotation electrodes so that the deviation comes into zero when a distance actually measured by the optical distance measuring device deviates from the target distance.

2. A seam welding apparatus that performs seam welding on layered steel plates, the seam welding apparatus comprising:
an articulated robot capable of setting a predetermined tolerance for a joint; and
a welding device attached to the robot and revolvable about a revolving axis of the robot,
the welding device comprising:
a pair of rotation electrodes for seam-welding the layered steel plates while applying pressure, the pair of rotation electrodes being rotatably supported by the welding device about respective rotation axes orthogonal to the revolving axis;
an electrode supporting frame that supports the rotating electrodes;
a supporting frame that rotatably supports the electrode supporting frame so that it is possible to change a direction of running when the rotating electrodes run on the steel plates;
a revolving means configured to revolve the electrode supporting frame provided on the supporting frame;
an optical distance measuring device provided on the supporting frame or the electrode supporting frame, the optical distance measuring device including:
a laser emission part disposed to face an edge of one of the layered steel plates, the laser emission part being configured to emit light toward the edge;
a light position detecting device configured to receive the light emitted from the laser emission part that reflects from the edge so as to detect a position of the received light reflected from the edge, the light position detecting device comprising a plurality of light receiving elements that are arranged in a row in an extending direction of the edge and receive different reflected lights corresponding to positions at which the light reflects from the edge of one of the layered steel plates;
a light projecting lens; and
a light receiving lens,
wherein the laser emission part, the light position detecting device, the light projecting lens, and the light receiving lens are provided at fixed positional relationships with respect to each other, and
the optical distance measuring device is configured to geometrically measure, based on which light receiving element of the plurality of light receiving elements of the light position detecting device receives the different reflected lights, a distance from the optical distance measuring device to the edge in a direction parallel to the rotation axes of the pair of rotation electrodes; and

a controller configured to:
set a target position of the welding device to set a target distance from the optical distance measuring device to the edge when the welding device is in the target position;
calculate a deviation of the distance measured by the optical distance measuring device from the target distance while the pair of rotation electrodes is running on the layered steel plates to perform seam welding; and
control the revolving means to adjust a running direction of the rotation electrodes so that the deviation comes into zero when a distance actually measured by the optical distance measuring device deviates from the target distance.

3. A method of performing seam welding by using a seam welding apparatus according to claim 1 , the method comprising:
teaching a welding line to the articulated robot;
setting the predetermined tolerance for the joint of the articulated robot;
setting the target distance in the controller;
measuring a distance to the edge of the steel plate by the optical distance measuring device when performing the seam welding;
calculating, by the controller, the deviation between a distance actually measured and the target distance; and
controlling, by the controller, the robot to adjust the running direction of the rotation electrodes so that the deviation comes into zero.

4. A robot control system comprising:
a processor;
a robot having an end effector revolvable about a revolving axis of the robot, the end effector including a pair of rotation electrodes for seam-welding two overlapped steel plates while applying pressure, the pair of rotation electrodes being rotatably supported by the end effector about respective rotation axes orthogonal to the revolving axis; and
an optical measuring device that is provided on the end effector,
the optical measuring device including:
a laser emission part disposed to face an edge of one of the two overlapped steel plates, the laser emission part being configured to emit light toward the edge;
a light position detecting device configured to receive the light emitted from the laser emission part that reflects from the edge so as to detect a position of the received light reflected from the edge, the light position detecting device comprising a plurality of light receiving elements that are arranged in a row in an extending direction of the edge and receive different reflected lights corresponding to positions at which the light reflects from the edge of one of the two overlapped steel plates;
a light projecting lens; and
a light receiving lens,
wherein the laser emission part, the light position detecting device, the light projecting lens, and the light receiving lens are prov

Assignees

• Yaskawa Electric Corp
• Honda Motor Co Ltd

Inventors

• Kawai Yasuhiro
• Yamaashi Kazuhiko
• Kobayashi Haruhiko
• Kaneko Mitsugu
• Kurimoto Noriko
• Nakakura Masami
• Sonoda Teppei

Classifications

• B23K11/3036

  Roller electrodes · CPC title

• B23K11/253

  the measured parameter being a displacement or a position · CPC title

• G05B2219/40613

  Camera, laser scanner on end effector, hand eye manipulator, local · CPC title

• B23K11/314

  Spot welding guns, e.g. mounted on robots · CPC title

• G05B2219/37423

  Distance, gap between tool and surface sensor · CPC title