Background
In the process of resistance spot welding of a white vehicle body, after a certain number of welding spots are welded, a certain amount of oxide can be formed on the surface of an electrode cap, the oxide can seriously affect the welding quality, and the resistance spot welding can be carried out again after the surface of the electrode needs to be polished again, so that the quality of the resistance spot welding is ensured.
On an automatic vehicle body production line, under a common condition, a welding tongs needs to weld metal materials of different grades at different moments, for example, sheet metal parts of various materials and various thicknesses, such as low alloy steel, high strength steel, hot forming steel and the like, may be welded successively, so that it is difficult for a technologist to specify specific grinding frequency, that is, it is impossible to determine how many times to weld and then grind an electrode.
In the prior art, when the electrode needs to be polished, the blank resistance of the electrode is detected under the condition of no resistance spot welding operation, and then whether the electrode needs to be polished is judged through the blank resistance. However, when this method is performed, it is necessary to stop the resistance spot welding operation of the welding tongs and perform idle driving without a welding material, which seriously affects the tact time of the automobile production line.
In another method, a predetermined number of times of welding is set, the number of times of welding is counted after the electrode of the last electrode of the welding tongs is ground, and the electrode of the welding tongs is ground uniformly when the number of times of welding reaches the predetermined number of times. However, since the predetermined number of times is set by the past experience, this method may cause the problem that the electrode of the electrode holder may have reached a state requiring the repair grinding before the predetermined number of times of welding is reached in the repair grinding period of the electrode holder, so that the electrode of the electrode holder may be damaged to affect the quality of the product, and the electrode of the electrode holder may have not actually reached the state requiring the repair grinding before the predetermined number of times of welding is reached to be repaired, which may shorten the service life of the electrode holder and increase the production cost.
Disclosure of Invention
The invention provides a method and a device for monitoring the electrode wear state of a resistance spot welding tongs, which can monitor the electrode wear state more accurately without stopping production and improve the production efficiency.
The invention provides a method for monitoring the electrode wear state of a resistance spot welding tongs, which comprises the following steps:
s1: detecting the pressing amount of a welding tongs electrode in each resistance spot welding process, and detecting whether the splashing phenomenon occurs in each resistance spot welding process;
s2: judging whether the press-in amount of the electrode of the welding tongs is larger than a press-in amount threshold value or not;
s3: counting the total times that the press-in amount of the electrode holder is greater than the press-in amount threshold value and the spattering phenomenon occurs in the process of the resistance spot welding with the latest first set times;
s4: and comparing the total times of the electrode holder electrode pressing-in amount which is greater than the pressing-in amount threshold and the spattering phenomenon with a second set time, and if the electrode holder electrode pressing-in amount which is greater than the pressing-in amount threshold and the total times of the spattering phenomenon which is greater than or equal to the second set time, sending a tip grinding prompt.
Further, in the detection of the spattering phenomenon, the method includes detecting a change in resistance of the electrode holder during resistance spot welding, and determining that the spattering phenomenon occurs if the change in resistance of the electrode holder conforms to a set change curve.
Further, in the detection of the spattering phenomenon, whether the spattering phenomenon occurs to the electrode of the welding tongs is detected by a visual detector.
Further, the threshold value of the pressing amount is 0.1-0.3 mm.
Further, the first set number of times is 5-10 times, and the second set number of times is greater than or equal to 60% of the first set number of times.
Further, the method further comprises the step of counting the number of times that the electrode holder electrode is pressed in the process of the resistance spot welding with the latest first set number of times and the total number of times that the spatter phenomenon does not occur, and if the number of times that the electrode holder electrode is pressed in is larger than the number of times that the electrode holder electrode is pressed in and the total number of times that the spatter phenomenon does not occur is larger than or equal to the second set number of times, an early warning prompt is sent.
Further, after the electrode of the welding tongs is judged to need to be polished, the method further comprises the steps of stopping resistance spot welding operation and controlling a polishing robot to polish the electrode of the welding tongs.
The invention also provides a device for monitoring the electrode wear state of the electrode holder for resistance spot welding, which comprises a measuring device for electrode stroke of the electrode holder, a splash judging device, a processing unit and a prompting unit, wherein the measuring device for electrode stroke of the electrode holder detects the press-in amount of the electrode holder in each resistance spot welding process and transmits the information of the press-in amount to the processing unit; and counting the total times of spattering phenomenon when the press-in amount of the electrode holder is greater than the press-in amount threshold value in the process of the resistance spot welding with the latest first set times according to the judgment and the information of the spattering judgment device, and if the total times is greater than or equal to the second set times, sending a tip grinding prompt by the processing unit through the prompt unit.
Further, the processing unit also counts the total number of times that the pressing amount of the electrode holder is greater than the pressing amount threshold value but no spattering phenomenon occurs in the latest resistance spot welding process of the first set number of times, compares the total number of times with the second set number of times, and sends out an early warning prompt through the prompting unit if the total number of times is greater than or equal to the second set number of times.
The device further comprises a grinding robot, wherein when the processing unit judges that the electrode of the welding tongs needs to be ground, the processing unit stops the operation of the electrode of the welding tongs and controls the grinding robot to grind the electrode of the welding tongs.
According to the invention, through analysis of the press-in amount and the splashing phenomenon of the electrode of the welding tongs, the state of the electrode of the welding tongs can be monitored in the working process without stopping a production line of resistance spot welding, and when the electrode of the welding tongs needs to be ground, a worker is accurately prompted to grind, so that the faulty work of the electrode of the welding tongs is avoided, the service life of the electrode of the welding tongs is prolonged, the production efficiency is improved, and the cost is reduced.
The foregoing description is only an overview of the technical solutions of the present invention, and in order to make the technical means of the present invention more clearly understood, the present invention may be implemented in accordance with the content of the description, and in order to make the above and other objects, features, and advantages of the present invention more clearly understood, the following preferred embodiments are described in detail with reference to the accompanying drawings.
Detailed Description
To further explain the technical means and effects of the present invention adopted to achieve the predetermined objects, the present invention will be described in detail below with reference to the accompanying drawings and preferred embodiments.
The invention provides a method and a device for monitoring the electrode wear state of a resistance spot welding tongs, which can monitor the electrode wear state more accurately without stopping production and improve the production efficiency.
Fig. 1 is a flowchart illustrating a method for monitoring a wear state of a resistance spot welding holder electrode according to an embodiment of the present invention, and as shown in fig. 1, the method for detecting a wear state of a resistance spot welding holder electrode according to an embodiment of the present invention includes the following steps:
s1: after the electrode of the electrode holder is polished for the last time, the pressing-in amount of the electrode holder in each resistance spot welding process is detected, and whether the splashing phenomenon occurs in each resistance spot welding process is detected.
In this embodiment, because in the resistance spot welding process, it is necessary to ensure that the electrode of the welding tongs always contacts with the sheet metal part to be welded, therefore, the pressing amount of the electrode of the welding tongs can be detected by the original electrode stroke measuring device of the welding tongs of the resistance spot welding production line, and no new equipment needs to be additionally added.
In the process of resistance spot welding, the sheet metal part to be welded can be changed into a molten state due to huge heat generated in the welding process, so that the heat change condition in the process of resistance spot welding can be reflected through the detection of the pressing amount of the electrode of the welding tongs.
When whether the spatter appears in the resistance spot welding process each time is detected, the spatter can be detected by detecting the change of the electrode resistance of the electrode holder, and if the change condition of the electrode resistance of the electrode holder accords with a set change curve, the spatter phenomenon appears in the resistance spot welding process. The resistance measurement can be carried out according to the resistance measuring device originally arranged at the electrode of the electrode holder in the resistance spot welding equipment, so that the additional equipment does not need to be added.
In the process of resistance spot welding, the surfaces of the sheet metal parts to be welded and the electrode of the welding tongs are changed into a molten state due to heating, if the heat is generated at an excessively high speed, the sheet metal parts to be welded are partially vaporized and are sprayed to the periphery in a splashing mode, and then the splashing phenomenon occurs, so that the heat change condition in the process of resistance spot welding can be reflected by detecting whether the splashing exists or not.
In other embodiments, whether the electrode of the welding tongs has the splash phenomenon or not can be detected through a visual detector.
S2: and judging whether the press-in amount of the electrode holder is larger than a press-in amount threshold value or not.
The threshold value of the pressing amount can be determined according to actual production requirements, and in the embodiment, the threshold value of the pressing amount can be 0.1-0.3mm, and is preferably 0.2 mm.
S3: and counting the total times of spattering when the press-in amount of the electrode holder is greater than the press-in amount threshold value in the process of the resistance spot welding with the latest first set times M.
The first set number of times M can be determined as required, generally M is 5-10 times, and for the same production line, the more the average weldable times between two times of coping electrode of the welding tongs, the larger the value of M is. In actual production, the electrode of the welding tongs can continuously work for 100 to 150 times after being polished, that is, the average welding times between two times of polishing of the electrode of the welding tongs is approximately 100 to 150 times, which is far more than the first set times M.
After the electrode of the welding tongs is ground, the grinding quality can be detected, and the electrode of the welding tongs can continue to work. Therefore, in the above step, when the actual number of spot welding times of the electrode holder is greater than the first set number M, the statistics of whether the press-in amount of the electrode holder is greater than the press-in amount threshold and the total number of times of occurrence of spatters may be restarted.
S4: and comparing the total times of the electrode pressing amount of the electrode of the welding tongs being larger than the threshold value of the pressing amount and the spattering with the second set times N, and if the total times of the electrode pressing amount of the welding tongs being larger than the threshold value of the pressing amount and the spattering being larger than or equal to the second set times N, sending a prompt of coping the electrode of the welding tongs.
In the present embodiment, the second set number of times N is greater than or equal to 60% of the first set number of times M. That is, if the first predetermined number of times M is 5 to 10 times, the second predetermined number of times N is 3 to 6 times. Preferably, the first set number of times M is 5 times, and the second set number of times N is 3 times, that is, in the last 5 resistance spot welding processes, if the press-in amount of the electrode holder is greater than the press-in amount threshold value for 3 times and the spatter phenomenon occurs at the same time, it indicates that the electrode of the electrode holder needs to be ground.
The pressing amount of the electrode of the welding tongs can reflect the integral melting condition of the surface of the sheet metal part to be welded, so the parameter can reflect the heat change condition in the resistance spot welding process on the whole; the spattering phenomenon occurs due to a temperature rise in a short time, and thus is more likely to reflect the thermal change of resistance spot welding at the moment of reaction. When the press-in amount of the electrode holder is larger than the press-in amount threshold value and the splashing phenomenon occurs in the resistance spot welding process, the fact that the electrode of the electrode holder possibly has problems can be explained, and when the number of times of the two phenomena occurring simultaneously is larger than the second set number of times within the first set number of times, the fact that the electrode of the electrode holder needs to be polished can be judged.
Further, the method also comprises the step of counting the total number of times that the electrode pressing amount of the electrode holder is larger than the threshold value of the pressing amount but no spattering occurs in the resistance spot welding process of the latest first set number of times M, and if the total number of times is larger than or equal to the second set number of times, giving out an early warning prompt to prompt a technician to pay attention to the condition of the electrode holder and checking the state of the electrode holder if necessary.
Further, the method also comprises the steps of analyzing all welding clamp electrodes on the resistance spot welding production line and displaying the welding clamp electrodes needing to be polished.
And after the electrode of the welding tongs is judged to need to be polished, stopping the resistance spot welding operation, and controlling a polishing robot to polish the electrode of the welding tongs.
In summary, in the embodiment, through analysis of the press-in amount and the spattering phenomenon of the electrode of the welding tongs, the state of the electrode of the welding tongs can be monitored in the working process without stopping the production line of resistance spot welding, and when the electrode of the welding tongs needs to be ground, a worker is accurately prompted to grind the electrode of the welding tongs, so that the faulty work of the electrode of the welding tongs is avoided, the service life of the electrode of the welding tongs is prolonged, the production efficiency is improved, and the cost is reduced.
The invention also provides a device for monitoring the electrode wear state of the electrode of the resistance spot welding tongs, which comprises a measuring device 10 for the electrode travel of the electrode tongs, a splash judging device 20, a processing unit 30 and a prompting unit 40, wherein the measuring device 10 for the electrode travel of the electrode tongs detects the press-in amount of the electrode tongs in each resistance spot welding process and transmits the information of the press-in amount to the processing unit 30; the spatter judging device 20 judges whether a spatter phenomenon occurs in each resistance spot welding process; the processing unit 30 judges whether the press-in amount of the electrode holder is greater than a press-in amount threshold value in each resistance spot welding process according to the information sent by the electrode stroke measuring device 10 of the electrode holder; counting the total times that the press-in amount of the electrode holder is greater than the press-in amount threshold value and the spattering phenomenon occurs in the process of the nearest resistance spot welding with the first set time M; and comparing the total times of the electrode pressing amount of the electrode holder which is larger than the pressing amount threshold and has the spattering phenomenon with a second set time N, and if the electrode pressing amount of the electrode holder which is larger than the pressing amount threshold and has the spattering phenomenon is larger than or equal to the second set time N, sending a grinding prompt of the electrode holder by the processing unit 30 through the prompting unit 40.
Further, the processing unit 30 may also count the total number of times that the electrode of the electrode holder is pressed into the electrode holder and spatters when the electrode of the electrode holder is pressed into the electrode holder during the resistance spot welding process for the latest first set number of times M, compare the total number of times with the second set number of times, and if the total number of times is greater than or equal to the second set number of times, the processing unit 30 sends an early warning prompt through the prompting unit 40 to prompt a technician to notice the quality of the electrode holder, thereby preventing accidents.
Further, the prompting unit 40 may include an alarm device and a display device, the alarm device may prompt a worker to notice by giving an alarm sound, and the display device may display the position of the electrode of the welding tongs to be polished on the display screen, so that the worker can perform positioning.
Further, the device further comprises a coping robot 50, when the processing unit 30 judges that the electrode of the welding tongs needs coping, the processing unit 30 stops the electrode operation of the welding tongs, and controls the coping robot 50 to carry out coping on the electrode of the welding tongs.
Although the present invention has been described with reference to a preferred embodiment, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.