A welding method for preventing false positives of missed points and timeouts in resistance welding equipment

Abstract

The present application belongs to the technical field of welding, and is used to solve the problem of current welding leakage. The present application relates to a welding method for preventing leakage and false alarm of resistance welding equipment, comprising: presetting welding completion time; a robot controller outputs a welding mode signal, the welding mode signal is high level, and the resistance welding equipment outputs current; the robot controller outputs "standard selection"; the robot controller outputs a start welding signal; when the resistance welding equipment receives the rising edge of the "start welding" signal and the "standard selection" is greater than 0, the resistance welding equipment performs system current output reaction, and outputs high level of the "standard selected" signal; the resistance welding equipment outputs high level of "welding completion"; the "standard selected" signal of the resistance welding equipment is pulled low; the "welding completion" signal of the resistance welding equipment is pulled low after the "start welding" signal is pulled low; the "start welding" signal is pulled low, if the preset time has passed and the signal is still not pulled low, the welding completion signal of the resistance welding equipment is pulled low, and the timeout alarm is ended. The present application improves production quality.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of resistance welding, and particularly relates to a welding method for preventing missed points and false alarms of resistance welding equipment. BACKGROUND

[0002] The resistance welding equipment has the characteristics of high production effect and no need for auxiliary materials, and is widely used in the field of automobile manufacturing. There are a large number of resistance welding equipment in the welding workshop of an automobile factory or a parts factory, especially in an automatic production line. The welding system of a resistance welding production line of a body-in-white generally includes a robot body, a robot controller, a welding controller, a welding tong, a grinder and the like. The robot body is connected with the robot controller; the robot controller is connected with the welding controller; the welding controller is connected with an external alternating current power supply; the output end of the controller is connected with the welding tong; the welding tong is installed on the robot body as an external shaft of the robot; and in the welding system of the automatic production line, the robot and the welding controller are generally connected through IO control or through an industrial bus (or an industrial Ethernet), such as Profibus, Profinet, EIP, CC-Link or the like. Regardless of the connection mode, there may be a missed point in actual production, that is, an individual position that should be welded on a workpiece is not welded, and the welding system does not alarm, so that the workpiece with the missed point flows into the next process, and finally causes a production accident.

[0003] Therefore, how to avoid the missed point of the automatic welding system is a problem to be solved. Generally, the problem is solved through two methods: 1. Through the addition of a subsequent inspection link, whether there is a missed point is found through manual inspection or image recognition, and if there is a missed point, secondary repair welding is performed; 2. Redundant welding points are added in the manufacturing process, so that even if a missed point occurs, the overall strength of the body is not affected, but this will reduce the production efficiency and cause energy waste. However, the above methods have obvious disadvantages, on the one hand, the efficiency is low, and on the other hand, the problem is not fundamentally solved.

[0004] Through repeated experiments and tracking on the above-mentioned phenomenon, it is finally found that the input system (such as a robot system or a PLC system) of the resistance welding equipment of the welding system and the resistance welding equipment belong to two independent systems, and work independently during welding. The key is that the “welding completion” signal of the resistance welding equipment and the “start welding” signal of the robot controller do not interact, and after the welding is completed, the “welding completion” signal of the resistance welding equipment outputs a high pulse of the set time, for example, 40 ms. Under normal circumstances, the robot controller can receive the pulse signal within the time, but occasionally the pulse signal cannot be received, which will cause the welding system to alarm or miss a point, such as the robot controller reporting a timeout. For example, if the working condition of the phenomenon changes, such as a poor network environment or electromagnetic interference and other factors, the welding system is prone to miss a point. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a welding method for resistance welding equipment that can effectively avoid leaks or false alarms due to timeouts in robot controllers, thereby improving production efficiency and quality.

[0006] The above-mentioned objective of the present invention is achieved through the following technical solution:

[0007] A welding method for preventing leaks and false timeouts in resistance welding equipment is characterized by: the welding system upon which this method is based including a welding controller and a robot controller, which are connected via one of the following: I / O signal lines, an industrial bus, or an industrial Ethernet; the signal definition includes two parts: resistance welding equipment output and resistance welding equipment input; the resistance welding equipment output includes at least welding completion and specification selection; the resistance welding equipment input includes at least specification selection, welding start, and welding mode; the resistance welding equipment has a preset welding completion time; normal operation of the resistance welding equipment requires pre-selection of the welding specification, and the welding specification value must be greater than 0;

[0008] The welding steps of the welding method are as follows:

[0009] Step 1: Pre-set the welding completion time of the resistance welding equipment;

[0010] Step 2: The robot controller outputs a welding mode signal. If the welding mode signal is high, the resistance welding equipment will output current; otherwise, the resistance welding equipment will not output current.

[0011] Step 3: The robot controller outputs "Specification Selection". "Specification Selection" is a set of signals encoded in BCD. The default selection is 0.

[0012] Step 4: The robot controller outputs a start welding signal. The rising edge of the start welding signal and the rising edge of the specification selection signal have an interval of at least Δt1, where Δt1 is the time that the "start welding" signal lags behind the "specification selection" signal in the resistance welding equipment input signals, and Δt1 is greater than or equal to 0.

[0013] Step 5: When the resistance welding equipment receives the rising edge of the "Start Welding" signal and the "Specification Selection" value is greater than 0, it responds with system current output and outputs a high-level "Specification Selected" signal. Note that there is a signal detection and software response time for the resistance welding equipment. The "Specification Selected" signal output by the resistance welding equipment lags behind the "Start Welding" signal output by the robot controller by a time Δt2, where Δt2 is the signal detection and response time of the resistance welding equipment, and Δt2 is greater than or equal to 0. Subsequently, the resistance welding equipment begins to output welding current.

[0014] Step 6, the resistance welding equipment no longer detects the "standard selection" signal and the "welding mode" signal during the output current process;

[0015] Step 7, the resistance welding equipment detects its own system failure for a time of △t3 before the rising edge of the output "welding completion", if there is a failure, the "welding completion" signal is not output, and a failure alarm is performed, if there is no failure, the high level of "welding completion" is output; wherein, △t3 is the system failure detection time, and △t3 is greater than or equal to 0;

[0016] Step 8, the "standard selection" signal of the resistance welding equipment is pulled low;

[0017] Step 9, the "welding completion" signal of the resistance welding equipment is pulled low after the "start welding" signal is pulled low, and is kept for a maximum of a preset △t4 time, △t4 is a preset welding timeout time, and △t4 is greater than 40 ms;

[0018] Step 10, after the robot controller detects the high level of the "welding completion" of the resistance welding equipment, the "start welding" signal is pulled low, if the "start welding" signal of the robot controller has not been pulled low after the high level of "welding completion" for a time of △t4, the "welding completion" signal of the resistance welding equipment is pulled low, and the resistance welding equipment performs a corresponding end timeout alarm.

[0019] Moreover, in step 7, the "welding completion" signal of the resistance welding equipment is kept for a maximum of a preset welding timeout time △t4.

[0020] The present application has the advantages and positive effects:

[0021] 1, the present application realizes the anti-missing point and timeout false alarm of the welding system without increasing the original signal definition, the "start welding" and "welding completion" two signals are coupled, the interaction between the resistance welding equipment and the robot controller is realized, the occurrence of missing welding points can be effectively prevented, and the corresponding alarm mechanism is provided, the subsequent manual or visual point detection and welding point redundant process design are avoided, the production efficiency is improved, and the energy is saved.

[0022] 2, the present application adds the timeout alarm failure of the resistance welding equipment, which is convenient for fault positioning after a problem occurs, and can improve the fault troubleshooting efficiency.

[0023] 3, the present application no longer detects the "standard selection" signal and the "welding mode" signal during the output current process, so as to prevent the change of the signal caused by unexpected situations from affecting the welding quality and the welding process. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 is the existing multi-working-condition interaction timing diagram;

[0025] Figure 2 is the signal interaction timing diagram of the present application;

[0026] Figure 3 is the key signal interaction flow chart of the present application.

[0027] Specific implementation

[0028] The structure of the present application is further described below in combination with the drawings and by way of examples. It should be noted that the examples are descriptive rather than limiting.

[0029] The existing resistance welding equipment completion signal is a high-level pulse signal output according to the set end time. The pulse signal is generally 40-150 ms. Further, the signal does not have a closed-loop control with the resistance welding equipment input system (such as a robot system or a PLC system). That is, the resistance welding equipment and the resistance welding equipment input system (such as a robot system or a PLC system) are independent of each other. Thus, there are occasional missed welds or false alarms due to the robot not detecting the pulse signal in time due to some faults, which poses a hidden danger to production and affects production efficiency.

[0030] The existing welding machine and resistance welding equipment input system (such as a robot system or a PLC system) are independent of each other in the end signal interaction process. After receiving the start signal, the welding machine outputs current according to the set specification. After the current output is completed, an end signal is output to the resistance welding equipment input system (such as a robot system or a PLC system). The resistance welding equipment input system (such as a robot system or a PLC system) detects whether the end signal is received within the preset timeout time after sending the start signal. Once the end signal is received, the start signal is removed, and then the robot moves to the next point and starts the next welding. Figure 1 The end and normal start timing diagram is shown in FIG.

[0031] Missed points:

[0032] As shown in FIG. Figure 1 When the individual welding points are close to each other, the time interval between the two weldings is very short, as shown in FIG. Figure 1 The third line, when the robot sends the start signal for the first time, the welding machine outputs the end signal. At this time, if the preset end signal time is long, or the distance between the two welding points is short, resulting in a short start time interval, the start signal is removed after receiving the end signal for the first time. At this time, the second start signal is output for the second welding, but the signal falls within the first end signal range. The resistance welding equipment input system (such as a robot system or a PLC system) judges that the second welding has been completed and immediately removes the second start signal. At this time, the welding machine has not actually output the current for welding. The robot then moves to the third point and starts welding. At this time, it will result in that the second point is not actually welded.

[0033] Time-out:

[0034] In a resistance welding system, the resistance welding equipment and the robot or PLC are usually connected by cables, and the above-mentioned interaction signals are transmitted between the cables, so that the signals may be unstable, thereby causing the resistance welding equipment input system (such as a robot system or a PLC system) to not detect the end signal within a preset timeout time after outputting the start signal for the first time and outputting the end signal correctly, at which time the resistance welding equipment input system (such as a robot system or a PLC system) will alarm to prompt that the welding end timeout, and stop working, and it is necessary to stop the line to troubleshoot the fault. However, at this time, the welding machine has already output correctly according to the preset process, which brings difficulties to troubleshooting and affects the production efficiency.

[0035] The present application provides a welding method for preventing missed points and false alarms of time-out of a resistance welding equipment, which only adds a closed-loop interaction timing of an end signal and a robot start signal on the resistance welding equipment, and without modifying the hardware of the resistance welding equipment, it is ensured that as long as the welding machine is in a normal working state, the end signal corresponding to each start signal will be received every time, and each welding start is a normal start process.

[0036] A welding method for preventing missed points and false alarms of time-out of a resistance welding equipment, please see Figures 2-3 The welding system based on the welding method comprises a welding controller and a robot controller, and the welding controller and the robot controller are connected through one of an IO signal line, an industrial bus and an industrial Ethernet; signal definition includes two parts: resistance welding equipment output and resistance welding equipment input; the resistance welding equipment output (i.e. the robot controller input) at least contains welding completion and specification selection; the resistance welding equipment input (i.e. the robot controller output) at least contains specification selection, start welding and welding mode; the resistance welding equipment has a pre-settable welding completion time; the resistance welding equipment needs to pre-select a welding specification for normal work, and the welding specification needs to be greater than 0;

[0037] The welding steps of the welding method are as follows:

[0038] Step 1, pre-set the welding completion time of the resistance welding equipment;

[0039] Step 2, the robot controller outputs a welding mode signal, and if the welding mode signal is high, the resistance welding equipment outputs current, otherwise the resistance welding equipment does not output current;

[0040] Step 3, the robot controller outputs "specification selection", which is a group of signals according to BCD coding, and the default selection is 0;

[0041] Step 4, the robot controller outputs a start welding signal, and the rising edge of the start welding signal is separated from the rising edge of the specification selection signal by at least a time interval of At1, wherein At1 is the time interval between the start welding signal and the specification selection signal in the input signal of the resistance welding device, and At1 is greater than or equal to 0;

[0042] Step 5, the resistance welding device outputs a system current output response and a high level of the specification selected signal when the rising edge of the start welding signal and the specification selection signal greater than 0 are received, wherein the resistance welding device has a signal detection and software response time, the specification selected signal output by the resistance welding device lags behind the start welding signal output by the robot controller by a time interval of At2, that is, At2 is the signal detection and response time of the resistance welding device, and At2 is greater than or equal to 0; and then the resistance welding device starts to output a welding current;

[0043] Step 6, the resistance welding device no longer detects the specification selection signal and the welding mode signal during the output of the current;

[0044] Step 7, the resistance welding device detects a system fault of itself at a time interval of At3 before the rising edge of the welding completion signal is output, and if there is a fault, the welding completion signal is not output, and a fault alarm is performed, and if there is no fault, a high level of the welding completion signal is output; wherein At3 is the system fault detection time, and At3 is greater than or equal to 0;

[0045] Further, the welding completion signal of the resistance welding device is maintained for a preset welding timeout time At4 at most;

[0046] Step 8, the specification selected signal of the resistance welding device is pulled low;

[0047] Step 9, the welding completion signal of the resistance welding device is pulled low after the start welding signal is pulled low, and is maintained for a preset At4 at most, At4 is a preset welding timeout time, and At4 is greater than 40 ms;

[0048] Step 10, after the robot controller detects the high level of the welding completion signal of the resistance welding device, the start welding signal is pulled low, and if the start welding signal of the robot controller has not been pulled low after the high level of the welding completion signal for a time interval of At4, the welding completion signal of the resistance welding device is pulled low, and the resistance welding device performs a corresponding end timeout alarm.

[0049] The application realizes the problem of anti-leakage point and timeout false alarm of the welding system without increasing the original signal definition. Further, the application also adds the timeout alarm fault of the resistance welding equipment, which is convenient for fault positioning after the problem occurs and improves the fault troubleshooting efficiency. Further, the "standard selection" signal and the "welding mode" signal are no longer detected in the output current process, which prevents the change of the signal caused by unexpected situations from affecting the welding quality and the welding process.

[0050] Although the embodiments of the application and the drawings are disclosed for the purpose of illustration, those skilled in the art can understand that various substitutions, changes and modifications are possible without departing from the spirit of the application and the appended claims, therefore, the scope of the application is not limited to the disclosed content of the embodiments and the drawings.

Claims

1. A method of resistance welding to prevent false positives for missed spots and time-outs in a resistance welding apparatus, the method comprising: The welding method is based on a welding system including a welding controller and a robot controller connected through one of IO signal line, industrial bus and industrial Ethernet; signal definition includes two parts: resistance welding equipment output and resistance welding equipment input; the resistance welding equipment output at least includes welding completion and specification selection; the resistance welding equipment input at least includes specification selection, start welding and welding mode; the resistance welding equipment has a pre-settable welding completion time; the resistance welding equipment needs to pre-select a welding specification for normal work, and the welding specification needs to be greater than 0; The welding steps of the welding method are as follows: Step 1, pre-set the welding completion time of the resistance welding equipment; Step 2, the robot controller outputs a welding mode signal, if the welding mode signal is high level, the resistance welding equipment outputs current, otherwise the resistance welding equipment does not output current; Step 3, the robot controller outputs specification selection, which is a group of signals according to BCD coding, and the default selection is 0; Step 4, the robot controller outputs a start welding signal, and the rising edge of the start welding signal has a time interval of △t1 with the rising edge of the specification selection signal, wherein △t1 is the time interval of the start welding signal lagging behind the specification selection signal in the resistance welding equipment input signal, and △t1 is greater than or equal to 0; Step 5, when the resistance welding equipment receives the rising edge of the start welding signal and the specification selection is greater than 0, the resistance welding equipment outputs a system current output response and a high level of specification selection signal; wherein the resistance welding equipment has signal detection and software response time, and the rising edge of the specification selection signal output by the resistance welding equipment lags behind the rising edge of the start welding signal output by the robot controller by △t2 time, that is, △t2 time is the signal detection and response time of the resistance welding equipment, and △t2 is greater than or equal to 0; then the resistance welding equipment starts to output welding current; Step 6, the resistance welding equipment no longer detects the specification selection signal and the welding mode signal during the output of the current; Step 7, the resistance welding equipment detects its own system failure △t3 time before the rising edge of the welding completion output, if there is a failure, the welding completion signal is not output, and a failure alarm is performed, if there is no failure, a high level of welding completion is output; wherein △t3 is the system failure detection time, and △t3 is greater than or equal to 0; Step 8, the specification selection signal of the resistance welding equipment is pulled low; Step 9, after the robot controller detects the high level of the welding completion of the resistance welding equipment, the start welding signal is pulled low, if the start welding signal of the robot controller has not been pulled low after the welding completion high level for △t4 time, the welding completion signal of the resistance welding equipment is pulled low, and the resistance welding equipment performs corresponding end timeout alarm, wherein △t4 is a pre-set welding timeout time, and △t4 is greater than 40 ms.

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