A resistance spot welding method comprises: performing test welding; and performing actual welding after the test welding, wherein in subsequent current passage in the test welding, current passage is performed by constant current control under a condition: 0.5≤Vtp/Vtm≤2.0 when tc<800 ms; 0.5−0.3×(tc−800)/800≤Vtp/Vtm≤2.0−0.5×(tc−800)/800 when 800 ms≤tc<1600 ms; and 0.2≤Vtp/Vtm≤1.5 when tc≥1600 ms, where Vtm is an average value of a voltage between the electrodes in main current passage in the test welding, and Vtp is an average value of a voltage between the electrodes in the subsequent current passage in the test welding, and wherein in main current passage in the actual welding, adaptive control welding is performed, and in subsequent current passage in the actual welding, current passage is performed by constant current control under a condition: 0.8×Itp≤Imp≤1.2×Itp, where Itp is a current in the subsequent current passage in the test welding, and Imp is a current in the subsequent current passage in the actual welding.

A resistance spot welding method comprises: performing test welding; and performing actual welding after the test welding, wherein in the test welding, 0.2≤Vtp/Vtm≤1.5 is satisfied where Vtm is an average value of a voltage between the electrodes in main current passage in the test welding and Vtp is an average value of a voltage between the electrodes in subsequent current passage in the test welding, and in each of main current passage and subsequent current passage in the actual welding, a time variation curve of an instantaneous amount of heat generated per unit volume and a cumulative amount of heat generated per unit volume that are stored in a corresponding one of the main current passage and the subsequent current passage in the test welding are set as a target, and adaptive control welding is performed to control a current passage amount according to the target.

The present invention relates to methods and apparatus for detection of fire states in the presence of welding activities. In some examples, the welding detection system may algorithmically calculate a risk of a fire state developing. In some embodiments, the welding fire detection and prevention system may communicate warning states to users, supervisors, equipment and/or building monitoring systems.

A method of joining a high entropy alloy is provided. The method of joining a high entropy alloy includes the steps of: arranging specimens made of a high entropy alloy to be in contact with each other; and diffusion joining the specimens made of the high entropy alloy by simultaneously applying a compressive stress and a current to a joint of the specimens within a range in which the high entropy alloy does not melt.

The present invention relates to methods and apparatus for detection of fire states in the presence of welding activities. In some examples, the welding detection system may algorithmically calculate a risk of a fire state developing. In some embodiments, the welding fire detection and prevention system may communicate warning states to users, supervisors, equipment and/or building monitoring systems.

To provide a spot welding system of high reliability which, when an abnormality such as a spot missing in spot welding occurs, is capable of more precisely and accurately detecting this immediately. Provided are a robot-side system having a robot and a robot-side control unit which controls driving of the robot; and a welder-side system having a welding gun mounted to the robot, and a welder-side control unit, in which the robot-side system includes: a storage unit which stores in advance appropriate thickness information of a welded part of members on which conducting spot welding; a welded-part thickness measurement unit which measures thickness of the welded part of members on which conducting spot welding; and a comparative determination unit which determines quality by comparing thicknesses of a welded part at the time of a welding start command and at the time of a welding completion command, and comparing with the appropriate thickness information of the welded part stored in the storage unit.

Provided is a welding management system that appropriately manages welding. The welding management system (100) includes a plurality of local magnetic sensors (10a to 10f) provided around a target joining position (K) and a correction magnetic sensor (20) curved to surround the target joining position (K). A data processing unit (30) generates information of a joining state of the target joining position (K) based on a difference between a detection value of each of the plurality of the local magnetic sensors (10a to 10f) and a detection value of the correction magnetic sensor (20).

A system managing a polishing state of tips of a welding gun of each welding robot installed in a production line of a vehicle includes: a robot controller storing tip polishing data including the number of polishing of the tips and a polishing amount of the tips generated after each tip dressing of the welding gun; and a server collecting the tip polishing data from the robot controller to store the collected data according to robot identification information of the robot and learning the store data through artificial neural network to generate reference data determining the polishing state of the tips corresponding to the robot identification information. The robot controller sets artificial neural network of the robot based on the reference data and determines whether a polishing state of the tips according to the number of polishing and the polishing amount of the tips is normal.

Provided is an evaluation system including: an analog-to-digital converting section comprised of a programmable circuit and configured to convert an analog signal, the analog signal being acquired by a physical quantity acquiring section and indicative of a time-series change of at least one of (i) welding current, welding voltage, or load applied to pieces to be welded and (ii) a displacement, during welding, of a welding head; and an evaluating section configured to determine, based on a digital signal, whether or not the time-series change satisfies a predetermined condition, wherein configuration data for configuring the programmable circuit is arranged to be changeable by a user.

A method of monitoring a manufacturing status of an electric resistance welded pipe manufactured by shaping a steel strip into a pipe and butt welding both end parts of the steel strip in a width direction along a lengthwise direction includes: arranging an imaging unit in a gas shield nozzle having an opening opposing a region in which both of the end parts of the steel strip in the width direction are butt welded and shielding the region with inert gas by ejecting the inert gas onto the region through the opening, the imaging unit having a visual filed including the region; and determining quality of a butt-welded part based on an image shot by the imaging unit.