JP6886707B2 - Stud welding method, stud welding equipment, and inspection method for stud welds - Google Patents

Description

The present invention relates to a stud welding method, a stud welding apparatus, and an inspection method of a stud weld, and in particular, effectively detects welding defects when stud welding a welding pin to a material to be joined, and covers the welding pin. Effectiveness of stud welding methods that can advantageously improve work efficiency when welding to joint materials, improved structure of stud welding equipment to realize such stud welding methods, and stud welds with poor welding. It relates to an inspection method that can be detected in a specific manner.

Conventionally, a stud welding method has been known as one of a methods for fixing a pin member such as a predetermined pin, bolt, or stud to a metal base material to be joined. Then, as a stud welding apparatus for carrying out this stud welding method, generally, a welding gun that holds a pin member and a charge for stud welding the pin member held by the welding gun to a base material are supplied. By having a power supply device and discharging the charge supplied from the power supply device between the pin member and the base material held by the welding gun, the pin member can be quickly and easily attached to the base material. Stud welding equipment configured to weld is well known.

Then, as such a stud welding apparatus, for example, Japanese Patent Application Laid-Open No. 2547702 (Patent Document 1), Japanese Patent Application Laid-Open No. 2002-172466 (Patent Document 2), Japanese Patent Application Laid-Open No. 2001-58270 (Patent Document 3), etc. Has clarified a stud welding machine and a stud welding method in which a stud is welded to a base material by using the discharge current of a charge charged in a capacitor. Such a capacitor discharge (CD) type stud welding method has a feature that it is possible to instantaneously discharge the electric charge stored in the capacitor and perform welding in a very short time, and other features. Compared to the welding method, it also has the feature that the base material is less distorted and burnt.

By the way, such CD type stud welding has, for example, a disc-shaped head and a rod-shaped leg erected on the disc-shaped head as disclosed in Japanese Patent No. 3112900 (Patent Document 4). It is suitably used when attaching and fixing a predetermined coating material such as a heat insulating material, a sound absorbing material, and a fireproof coating material to a metal base material using the stud welding pin provided. ..

However, when a covering material arranged so as to cover a metal base material is to be fixed to the base material by using such a stud welding pin, welding between the welding pin and the base material is performed. There is an inherent problem that the welding pin falls off from the base material due to the defect that the welding between them cannot be sufficiently performed. That is, the tip of the leg of the welding pin penetrates the covering material and reaches the surface of the base material, and stud welding is performed between the tip of the leg of the welding pin and the surface of the base material. This is done so that the welding pin is welded (welded) to the base material, but such a welded part (welded part) is covered with the covering material and cannot be visually observed. Therefore, it was extremely difficult to determine whether or not the welding pin was surely welded to the base material only by performing the stud welding operation on the base material.

Therefore, in order to determine whether or not the welding pin is reliably welded to the base material, conventionally, after the stud welding operation is performed, a force is applied to the welding pin by the operator's hand. , Palpation to determine whether or not the welding pin has come off has been generally performed. In this tactile sensation, welding of the portion to be welded to the base material of the welding pin can be completely realized by applying a force such as bending the welding pin after performing a stud welding operation of the welding pin on the base material. If there is no welding, or if the welding is completed in an incomplete state and it seems that welding is possible at first glance, such force causes the welding pin to separate from the base material. , It is possible to judge whether or not the stud welding is surely performed. By performing such palpation, it is possible to reliably detect welding pins that are hardly welded to the base material, but the welding amount is not sufficient, and the welding pins are in a half-welded state. Therefore, there is a problem that it is difficult to reliably detect due to individual differences of workers who perform palpation, that is, differences in force, number of times, direction, etc. applied during palpation. Furthermore, since such palpation will apply force to the welded part between the weld pin and the base material and the weld pin itself, there is a risk of damage when it is performed on a good welded product. As a result, there was also an inherent problem of new defective parts.

Japanese Patent No. 2547702 JP-A-2002-172466 Japanese Unexamined Patent Publication No. 2001-58270 Japanese Patent No. 3112900

Here, the present invention has been made in the context of such circumstances, and the problem to be solved thereof is welding when stud welding a welding pin to a metal base material to be welded. It is an object of the present invention to provide a stud welding method capable of advantageously detecting a material that is not completely welded to a base material due to a defect without performing manual work such as tactile sensation, which is different from welding work. Further, in the present invention, it is also an object of the present invention to provide a stud welding apparatus capable of effectively realizing such a stud welding method. In addition, it is also an object of the present invention to provide an inspection method capable of effectively detecting a stud welded product having poor welding.

Then, in the present invention, in order to solve such a problem, the tip of the welding pin is welded to the material to be welded by applying a predetermined welding current between the welding pin and the material to be welded. In the stud welding method in which the welding pin is squeezed, the welding pin is pressed against the material to be welded while a welding current is applied between the welding pin and the material to be welded. After the welding process of welding to the material to be welded and the completion of the welding process, a predetermined inspection current is applied to the welding pin and the material to be welded while applying a tensile force between the welding pin and the material to be welded. By energizing between the materials and softening the welded portion between the weld pin and the material to be welded, the presence or absence of separation between the weld pin and the material to be welded is examined, and a weld pin with poor welding is detected. The gist thereof is a stud welding method characterized by including an inspection step to be performed.

According to one of the desirable aspects of the stud welding method according to the present invention, the welding gun is provided with a magnet capable of attracting and holding the welding pin, and the welding pin is held by the magnet. In the above, a configuration in which the tensile force is generated between the welding pin and the material to be joined by pulling the welding gun away from the material to be joined is advantageously adopted. Will be.

Further, in one of the preferred embodiments of the stud welding method according to the present invention, the welding current is energized while the welding pin is attracted and held by a magnet provided in the welding gun. After the completion of the energization operation, the tensile force is applied by applying a force in the direction of separating the welding pin from the material to be joined under the state of being attracted and held by the magnet of the welding pin. The inspection current is energized after it is generated.

Furthermore, in one of the other desirable embodiments of such a stud welding method according to the present invention, the material to be joined is a base steel plate, and the heat insulating material arranged so as to cover the base steel plate is penetrated. The welded pin will be welded to the base steel plate.

Furthermore, in the present invention, a stud welding device is provided in which a predetermined welding current is applied between the welding pin and the material to be welded so that the tip of the welding pin is welded to the material to be welded. , A gun shaft arranged and supported in the gun body, a power feeding plug attached to the tip of the gun shaft, attracting and holding the welding pin with a magnet, and energizing the welding pin, and the gun. A first trigger means for outputting a welding signal for passing the welding current in a state where the welding pin held by the power feeding plug attached to the tip of the shaft is pressed against the material to be joined, and the welding pin. Under the holding state by the power feeding plug, a predetermined inspection current is applied to the welding pin and the welding material by a tensile force generated by the movement of the gun shaft in a direction away from the welding material with respect to the welding pin. A welding gun having a second trigger means for outputting an inspection signal for flowing between the welding pin and the welding pin and the material to be joined is provided by the welding signal output from the first trigger means. The inspection is performed by the first energization circuit that causes the welding pin to be welded to the material to be welded by energizing the welding current and causing arc discharge, and the inspection signal output from the second trigger means. By applying an electric current between the welding pin and the material to be joined to soften the welded portion between the welding pin and the material to be joined, the presence or absence of separation between the welding pin and the material to be joined is examined. A stud welding apparatus characterized in that a second energizing circuit for detecting a welding pin with poor welding is further provided is also a gist thereof.

In addition, in the present invention, by applying a predetermined welding current between the welding pin and the material to be welded, the tip of the welding pin is welded to the material to be welded to inspect the stud welded product. By the method, a predetermined inspection current is applied between the welding pin and the material to be joined while applying a tensile force between the welding pin and the material to be joined in the stud welded product, and the welding pin and the material to be joined are subjected to a predetermined inspection current. A method for inspecting a stud welded object, which comprises softening a welded portion with the welded material, examining the presence or absence of separation between the welded pin and the welded material, and detecting a welded pin with poor welding. Is also the gist of this.

As described above, according to the stud welding method according to the present invention, while pressing the welding pin held by the welding gun against the material to be welded, a predetermined welding current is applied between the welding pin and the material to be welded to carry the welding pin. After the welding process of welding the weld pin to the material to be welded, a predetermined inspection current is applied to the weld pin and the material to be welded while applying a tensile force in the direction of pulling the weld pin away from the material to be welded. By energizing between the above and softening the welded portion between the welding pin and the material to be welded formed in the above-mentioned welding step, if the welded portion is poorly welded, the tensile force is applied. Since the welded portion will be broken, it is possible to effectively detect a welded pin with poor welding by examining the presence or absence of separation between the welded pin and the material to be joined. As a result, the manual welding defect detection work such as palpation, which is required after the conventional stud welding work, is not required at all, and the work time required for stud welding can be advantageously shortened.

Further, according to such a stud welding method according to the present invention, after the stud welding step, a detection current is simply applied to the welding pin while applying a predetermined tensile force. Unlike the conventional welding defect detection work by tactile sensation, there is no difference in the detection accuracy by the operator, and in addition to being able to detect welding defects with high accuracy, for good welding products. The risk of damage can also be effectively suppressed or avoided.

Moreover, in the inspection process in the stud welding method according to the present invention, the same path as the current path for performing stud welding is used so that the inspection current flows between the welding pin and the material to be joined. Therefore, it is possible to enjoy the advantage that it is not necessary to newly install an electric current path for detecting welding defects.

Further, according to the stud welding apparatus according to the present invention for carrying out such a stud welding method, the welding pin is attracted and held by the magnet, and the welding pin is energized. A welding current in a state where the welded pin held by the power feeding plug attached to the tip of the gun shaft is pressed against the material to be joined by using the gun shaft in which the configured power feeding plug is attached to the tip. A predetermined inspection current is applied to the weld pin by the first trigger means for outputting the welding signal to flow the weld pin and the tensile force generated by applying a force in the direction away from the material to be welded to the weld pin. Since a welding gun having a second trigger means for outputting an inspection signal to flow between the material and the material is used, the welding signal output from the first trigger means is used to join the welding pin to the welded pin. A welding current is energized between the material and the material, the arc is discharged, and after the welding process is performed, the inspection current is energized between the welding pin and the material to be joined by the inspection signal output from the second trigger means. By softening the welded portion between the weld pin and the material to be welded, the inspection process for detecting the weld pin with poor welding by checking for the presence or absence of separation between the weld pin and the material to be welded is effectively carried out. It can be done.

Further, according to the method for inspecting a stud weld according to the present invention, a predetermined inspection current is applied between the weld pin and the material to be joined while applying a tensile force between the weld pin and the material to be joined in the stud weld. Since it is only necessary to energize and check for separation between the welding pin and the material to be joined, it is possible to detect welding defects with higher accuracy than the conventional inspection method that detects welding defects by palpation. At the same time, there is a feature that the risk of damaging the good welded product can be effectively suppressed or avoided.

It is explanatory drawing which shows the state in each step of the stud welding method according to this invention, (a) shows the process of welding a welding pin to a base steel plate, (b) is a welding pin and An example of an inspection process for checking whether or not stud welding with the base steel plate is normally performed is shown, and (c) shows an example of an inspection process for a weld pin with poor welding, (d). ) Indicates that the welding pin, which was poorly welded, was separated from the base steel plate by the inspection process. It is explanatory drawing which shows typically an example of the structure of the stud welding apparatus which adopted the stud welding method according to this invention. It is explanatory drawing which shows schematic structure of the welding gun used in the stud welding apparatus which follows this invention. It is explanatory drawing which shows roughly the state inside the welding gun at the time of carrying out the stud welding method according to this invention using the welding gun shown in FIG. 3, and (a) is an example of the state in the welding process. It is shown, and (b) shows an example of the state in the inspection process.

Hereinafter, in order to clarify the present invention more concretely, a typical embodiment of the present invention will be described in detail with reference to the drawings.

First, in FIGS. 1 (a) to 1 (d), a covering material 4 such as a heat insulating material having a predetermined thickness for covering the metal base steel plate 2 to be welded is formed in a plate shape. When fixing using a welding pin 6 having a head and rod-shaped legs, the welding pin 6 is stud-welded to the base steel plate 2 according to the stud welding method according to the present invention. The situation at each is outlined. Then, in the stud welding method according to the present invention, as shown in FIG. 1A, the welding pin 6 held by a predetermined welding gun (not shown here) is attached to the base steel plate 2. On the other hand, while pressing [in the direction indicated by the white arrow in FIG. 1A], a predetermined welding current is energized between the welding pin 6 and the base steel plate 2 to cause an arc discharge. Similar to the conventional stud welding method, a part of the tip of the welding pin 6 and a part of the surface of the base steel plate 2 are melted, and as shown in FIG. 1B, the tip of the welding pin 6 and the base steel plate 2 are melted. A welding step in which and is welded will be carried out.

Then, in the stud welding method according to the present invention, after the welding step, as shown in FIG. 1B, a predetermined tensile force is applied between the welding pin 6 and the base steel plate 2. More specifically, between the welding pin 6 and the base steel plate 2 while applying a tensile force in the direction in which the welding pin 6 is separated from the base steel plate 2 [the direction indicated by the white arrow in FIG. 1 (b)]. An inspection step is carried out in which a predetermined inspection current is applied to the welding pin 6 to inspect whether or not the welding pin 6 is separated from the base steel plate 2.

In this inspection step, as shown in FIG. 1B, the stud welding between the welding pin 6 and the base steel plate 2 is normally performed, that is, the tip of the welding pin 6 and the base steel plate 2 When the surface can be sufficiently melted and the joint portion 8 between the welding pin 6 and the base steel plate 2 becomes a welded portion having a sufficiently large size and is formed in a sound state, the welding portion 8 is formed. The resistance value of such a joint 8 becomes small, and even if an inspection current is applied between the welding pin 6 and the base steel plate 2, the joint 8 does not soften to the extent that it melts. Even if a tensile force is applied between the welding pin 6 and the base steel plate 2 when the inspection current is applied, the welding pin 6 does not separate from the base steel plate 2.

On the other hand, as shown in FIG. 1 (c), in the welding process, the tip of the welding pin 6 and the surface of the base steel plate 2 were not sufficiently melted, so that the welding pin 6 and the base steel plate 2 were combined. In the case where only a small joint 8'is formed between them and the welding process is completed in an incompletely welded state, the electric resistance value becomes high at such a small joint 8'. Therefore, by applying an inspection current between the welding pin 6 and the base steel plate 2, the joint portion 8'will be softened or melted. Therefore, when an inspection current is applied between the welding pin 6 and the base steel plate 2 while applying a tensile force between the welding pin 6 and the base steel plate 2, the joint portion is in such an incomplete welded state. 8'is broken, so that the welding pin 6 and the base steel plate 2 are disconnected from each other, so that the welding pin 6 is separated from the base steel plate 2 as shown in FIG. 1 (d). It becomes. Therefore, by detecting the presence or absence of such detachment, a welding defect between the welding pin 6 and the base steel plate 2 can be immediately detected.

As described above, according to the stud welding method according to the present invention, since the welding process and the inspection process are continuously performed in one stud welding operation, the conventional stud welding operation is performed after the welding operation. Further, it is not necessary to detect welding defects by palpation by an operator, and the work time required for stud welding of the welding pin 6 to the base steel plate 2 can be advantageously shortened.

Further, according to the stud welding method, the inspection step performed after the welding step is for detecting between the welding pin 6 and the base steel plate 2 while applying a predetermined tensile force to the welding pin 6. In addition to being able to detect welding defects with high accuracy, there is no difference in the detection accuracy by the operator, unlike the conventional welding defect detection work by palpation, because only the current is applied. Therefore, the risk of damaging the good welded product can be effectively eliminated.

In addition, in the inspection process of the stud welding method according to the present invention, the inspection current is applied to the welding pin by using the same path as the current path for stud welding the welding pin 6 to the base steel plate 2. By allowing the current to flow between the base steel plate 2 and the base steel plate 2, it is possible to advantageously enjoy the advantage that it is not necessary to newly install a current path for inspection for detecting welding defects.

By the way, an example of a stud welding apparatus capable of preferably carrying out such a stud welding method according to the present invention is schematically shown in FIG. In FIG. 2, the welding device 10 for stud welding the welding pin 12 and the base steel plate 14 to be joined is a welding current that energizes between the welding pin 12 and the base steel plate 14 to be joined. It is composed of a power feeding device 16 for supplying an inspection current and a welding gun 18 electrically connected to the power feeding device 16.

There, the power feeding device 16 is composed of a first energizing circuit 20 and a second energizing circuit 30. The first energization circuit 20 is composed of a first power supply device 22, a first capacitor 24, and a first switch means 26, and is welded by opening and closing the first energization circuit 20 by the switch means 26. An arc discharge is generated between the pin 12 and the base steel plate 14, and a predetermined welding current for stud welding the welding pin 12 to the base steel plate 14 can be energized. Further, the second energization circuit 30 is composed of a second power supply device 32, a second capacitor 34, and a second switch means 36, and the second energization circuit 30 is opened and closed by the switch means 36. A predetermined inspection current can be energized between the welding pin 12 and the base steel plate 14.

More specifically, the first energization circuit 20 described above performs an arc discharge for joining the welding pin 12 and the base steel plate 14 by a stud welding method, similarly to the conventional capacitor discharge type stud welding device. A first power supply device 22 and a first capacitor 24 having a capacity capable of securing a voltage or current that can be generated are provided, and the first power supply device 22 to the first capacitor 24 Therefore, the charge required for stud welding is supplied and stored. Then, one pole (here, the positive electrode) of the first energization circuit 20 is connected to the base steel plate 14 via the first switch means 26, while the other pole (here, the negative electrode) is connected. , It is electrically connected to the welding pin 12 held by the welding gun 18.

Further, the second energizing circuit 30 is for supplying an inspection current in the stud welding method according to the present invention, and when the stud welding between the welding pin 12 and the material to be joined 14 is defective. The second power supply device 32 and the second capacitor 34 having a capacity capable of securing a voltage and a current capable of softening or melting the poorly welded portion are provided. From 32, the necessary charge is supplied to the second capacitor 34 and accumulated. Then, one of the poles (here, the positive electrode) of the second energizing circuit 30 is connected to the base steel plate 14 via the second switching means 36 so as to be parallel to the first energizing circuit 20. On the other hand, the other electrode (here, the negative electrode) is electrically connected to the welding pin 12 held by the welding gun 18.

Various known switching elements such as thyristors and FETs will be used for the first switching means 26 and the second switching means 36 described above, and the first trigger means and the second trigger means described later will be used. The ON / OFF of the switch means 26 and 36 is controlled by a welding signal and an inspection signal output from the switch means 26 and 36 through a control circuit (not shown here). Then, by closing (turning on) such a first switch means 26 and a second switch means 36, one pole of the first capacitor 24 or the second capacitor 34 is selectively subjected to the base steel plate 14. A predetermined welding current or inspection current is energized between the welding pin 12 and the base steel plate 14 by the electric charges stored in the capacitors 24 and 34. .. When a thyristor is used for the switching means 26 and 36, as is well known, a predetermined commutation circuit or the like is provided to control the ON / OFF of the thyristor. ..

On the other hand, the welding gun 18 that holds the welding pin 12 supplies the welding current required for stud welding to the welding pin 12 while holding the welding pin 12 in the same manner as the welding gun conventionally used for stud welding. It has a welding gun main body 40a provided with a power feeding plug 46 for performing stud welding, and a grip portion 40b for a worker performing stud welding to hold such a welding gun main body 40a safely and with good workability. It is configured.

A button 54 operated by the operator's hand is attached to the grip portion 40b of the welding gun 18, which supplies a welding current for stud welding the welding pin 12 to the base steel plate 14. It constitutes the first trigger means. That is, by operating the button 54, a welding signal is output from the welding gun 18 to the power feeding device 16, and the welding signal turns on the first switching means 26 of the first energizing circuit 20. The electric charge charged in the first capacitor 24 is energized between the welding pin 12 and the base steel plate 14 as a welding current.

Further, in the welding gun 18, a gun shaft 44 having a substantially cylindrical shape is provided in the welding gun main body 40a in the welding gun main body 40a, as is clearly shown from FIG. It is supported and arranged by a fixing portion 42 provided on the welding gun main body 40a so as to be movable in the axial direction (left-right direction in FIG. 3).

Then, at one tip 44a of such a gun shaft 44, a feeding plug 46 for holding a welding pin 12 and supplying a welding current to the welding pin 12 is conventionally used for stud welding. It has a structure similar to that of the power feeding plug provided in the gun, and is attached so as to protrude from the welding gun main body 40a. A magnet 48, which is a permanent magnet, is attached to the power feeding plug 46, and the welding pin 12 is attracted to and held by the magnetic force of the magnet 48 with respect to the power feeding plug 46.

Further, here, a spring 50, which is a compression coil spring, is externally inserted into the gun shaft 44 between the tip portion 44a and the fixing portion 42 provided on the welding gun main body 40a. The urging means is configured so that the urging force is applied in the direction of pushing the gun shaft 44 out of the welding gun main body 40a.

Furthermore, the end 44b on the side opposite to the tip 44a on the side where the power feeding plug 46 of the gun shaft 44 is attached does not come off from the fixing portion 42 that movably supports the gun shaft 44 in the axial direction. The size is set so that the amount of movement of the gun shaft 44 in the direction of pushing the gun shaft 44 outward from the inside of the welding gun body 40a is limited by the urging force of the spring 50 so that the gun shaft 44 does not come off from the welding gun body 40a. There is. A pressure sensor 52 is attached between the end 44b of the gun shaft 44 and the fixing portion 42, so that the gun shaft 44 is pushed out from the inside of the welding gun body 40a. Pressure is now detected. That is, such a pressure sensor 52 pulls the welding gun 18 away from the base steel plate 14 after the welding process is completed, in other words, moves the gun shaft 44 so as to retract, and the magnet 48 is attached to the power feeding plug 46. It is possible to detect the tensile force acting when the welding pin 12 attracted and held by the magnetic force of the above is removed from the power feeding plug 46, and by detecting this tensile force, the output from the pressure sensor 52 can be detected. The welding pin 12 is used as an inspection signal from the second trigger means for supplying an inspection current that is energized between the welding pin 12 and the base steel plate 14.

By the way, when the welding pin 12 is stud welded to the base steel plate 14 according to the stud welding method according to the present invention using the welding apparatus 10 having such a configuration, for example, the following is performed. Will be.

First, the first capacitor 24 in the first energizing circuit 20 of the power feeding device 16 is charged with an amount of electric charge required for stud welding from the first power supply device 22, and the second energizing circuit 30 is charged. As shown in FIG. 4A, the power supply plug 46 of the welding gun 18 is charged with the second capacitor 34 by the electric charge required for the inspection of welding defects from the second power supply device 32. On the other hand, after the welding pin 12 is attracted and held by the magnetic force of the magnet 48, the welding gun 18 is advanced toward the base steel plate 14, so that the tip of the welding pin 12 penetrates the covering material 15. The surface of the base steel plate 14 is pressed against the surface of the base steel plate 14 with a predetermined pressing force. At this time, due to the pressing force that presses the welding gun 18 toward the base steel plate 14, the gun shaft 44 moves in the direction of entering the welding gun main body 40a, the end portion 44b of the gun shaft 44 separates from the pressure sensor 52, and the gun The spring 50 arranged between the tip portion 44a of the shaft 44 and the fixing portion 42 is compressed, and an urging force is applied in the direction of pushing the gun shaft 44 out of the welding gun body 40a. In this way, the welding pin 12 held by the power feeding plug 46 is pressed against the base steel plate 14 by the pressing force (the urging force generated by the spring 50) that pushes the welding gun 18 toward the base steel plate 14.

Under such a state, the first energization circuit 20 is generated by operating the button 54 provided on the grip portion 40b of the welding gun 18 to generate a welding signal and transmitting the welding signal to the power feeding device 16. The first switching means 26 of the above is turned on. Then, the charge stored in the first capacitor 24 is energized between the welding pin 12 and the base steel plate 14 as a welding current, and between the tip of the welding pin 12 and the surface of the base steel plate 14. , An arc discharge is generated, and a part of the tip of the welding pin 12 and a part of the surface of the base steel plate 14 are melted. The welding step in which 14 (2) is welded is carried out.

Next, after the welding step is completed, as shown in FIG. 4B, by moving the welding gun 18 in the direction of pulling it away from the base steel plate 14, the gun has moved in the direction of entering the welding gun main body 40a. The shaft 44 is moved to its original position by the urging force of the spring 50, that is, the end portion 44b of the gun shaft 44 is in contact with the pressure sensor 52, and the urging force generated by the spring 50 is eliminated. It becomes. Then, when the welding gun 18 is further moved in the direction of pulling away from the base steel plate 14, the welding pin 12 is attracted and held by the magnetic force of the magnet 48 with respect to the feeding plug 46 of the welding gun 18. The movement of the welding gun 18 in the direction of pulling it away from the base steel plate 14 causes a force in the direction of pulling the welding pin 12 away from the base steel plate 14, and a tensile force is generated between the welding pin 12 and the base steel plate 14. It will occur.

Then, the tensile force generated between the welding pin 12 and the base steel plate 14 in this way is also applied to the gun shaft 44 while the welding pin 12 is attracted to the power feeding plug 46 by the magnetic force of the magnet 48. To act, it will be detected by the pressure sensor 52. Then, when such a tensile force reaches a predetermined pressure, it is output as an inspection signal from the pressure sensor 52, and this inspection signal is transmitted to the power feeding device 16 to obtain a second. The second switch means 36 of the energizing circuit 30 is turned on. Then, under the condition that a tensile force is applied between the welding pin 12 and the base steel plate 14, the electric charge stored in the second capacitor 34 is inspected between the welding pin 12 and the base steel plate 14. It will be energized as.

Due to the inspection current applied between the welding pin 12 and the base steel plate 14, the joint portion (welded portion) formed between the welding pin 12 and the base steel plate 14 is formed according to the welding state. If it is softened and the welding at the joint is insufficient (formation of the joint 8'), the tensile force acting between the welding pin 12 and the base steel plate 14 causes the welding pin 12 to be softened. Is separated from the base steel plate 14 and separated from the base steel plate 14, and is detected as a welding defect. In this way, the inspection process is carried out.

On the other hand, when the stud welding between the welding pin 12 and the base steel plate 14 is performed well and a sound joint portion 8 is formed between them, the inspection current by such an inspection step is measured. Even after energization, the welding pin 12 does not separate from the base steel plate 14, and in that case, the welding gun 18 is more attractive than the magnetic force of the magnet 48 that is attracting the welding pin 12 to the power feeding plug 46. When the tensile force generated by moving the welding pin 12 in the direction of pulling it away from the base steel plate 14 becomes large, the welding pin 12 comes off from the power feeding plug 46, the inspection process is completed, and the stud welding of the welding pin 12 to the base steel plate 14 is completed. The work will be completed.

According to such a welding device 10, when performing stud welding work on the base steel plate 14 of the welding pin 12, the welding pin 12 is held by the welding gun 18 and used as the base as in the conventional stud welding device. Welding is performed only by operating the button 54 while pressing against the steel plate 14 to perform stud welding between the welding pin 12 and the base steel plate 14, and then pulling the welding gun 18 away from the base steel plate 14. A stud welding step between the pin 12 and the base steel plate 14 and an inspection step for confirming whether or not the welding pin 12 is sufficiently welded to the base steel plate 14 can be sequentially performed. From this point, it is no longer necessary to perform the work of detecting welding defects by touching by the operator after the welding work, which has been performed in the conventional stud welding work, and the work time required for stud welding of the welding pin 12 to the base steel plate 14 is reduced. In addition to being able to be shortened advantageously, welding defects can be detected with high accuracy without any difference in detection accuracy by the operator as in palpation, and damage to good welded products is damaged. The fear of giving will also be effectively eliminated.

Although the typical embodiments of the present invention have been described in detail above, they are merely examples, and the present invention is limited by specific descriptions relating to such embodiments. It should be understood that it is not interpreted as.

For example, in the above-described embodiment, the compression coil spring is adopted as the spring 50 used as the urging means, but the urging force can be applied in the direction of pushing the gun shaft 44 outward from the inside of the welding gun body 40a. If possible, various known spring products such as leaf springs and elastic rubber can be used.

Further, as a second trigger means when an inspection current is applied between the welding pin 12 and the base steel plate 14, the pressure sensor 52 is used here in the direction in which the welding pin 12 is to be separated from the base steel plate 14. The tensile force was detected and used as an inspection signal from the second trigger means, but any such force that can detect the tensile force between the welding pin 12 and the base steel plate 14 can be detected. For example, it is possible to use a sensor other than the pressure sensor or adopt a limit switch structure. For example, when the gun shaft 44 is moved outward in the welding gun main body 40a by a tensile force, a limit switch that operates according to the movement amount is provided in the welding gun main body 40a, and the limit switch is a predetermined amount. When a movement is detected, an inspection signal may be output as a second trigger means.

Further, in the inspection step exemplified in the above-described embodiment, the welding pin 12 separated from the base steel plate 14 by the inspection current applied between the welding pin 12 and the base steel plate 14 and detected as a welding defect is welded. While being attracted to the power feeding plug 46 of the gun 18 by the magnetic force of the magnet 48, it is pulled out from the covering material 15, but such a poorly welded welding pin 12 is removed from the power feeding plug 46 by an operator. After that, a new welding pin 12 is attached to the power feeding plug 46, and the stud welding operation is performed again. It is also possible to perform the stud welding operation by pressing the tip of the welding pin 12 against the base steel plate 14 again without removing the welding pin 12 detected as such a welding defect from the power feeding plug 46. Although it is possible, the tip of the welding pin 12 that has been poorly welded by performing the stud welding operation once has been deformed from the initial shape, so even if the stud welding operation is performed as it is, the welding failure will occur again. There is a high possibility that it will be welded. Therefore, preferably, as described above, the stud welding operation is performed again after replacing the welding pin 12 with a new one.

In addition, although not listed one by one, the present invention can be carried out in a mode in which various changes, modifications, improvements, etc. are added based on the knowledge of those skilled in the art, and such a mode of implementation is described. It goes without saying that all of them belong to the category of the present invention as long as they do not deviate from the gist of the present invention.

2 Base steel plate 4 Coating material 6 Welding pin 8, 8'joint 10 Welding device 12 Welding pin 14 Base steel plate 15 Coating material 16 Feeding device 18 Welding gun 20 First energizing circuit 22 First power supply device 24 First capacitor 26 First switching means 30 Second energizing circuit 32 Second power supply device 34 Second capacitor 36 Second switching means 40a Welding gun body 40b Gripping part 42 Fixed part 44 Gun shaft 44a Tip part 44b End part 46 Power supply Plug 48 Magnet 50 Spring 52 Pressure sensor 54 Button

Claims (6)

In a stud welding method in which a predetermined welding current is applied between a welding pin and a material to be welded so that the tip of the welding pin is welded to the material to be welded.
The welding pin is welded to the material to be joined by pressing the welding pin held by the welding gun against the material to be joined and applying a welding current between the welding pin and the material to be joined. Welding process and
After the completion of the welding process, a predetermined inspection current is applied between the welding pin and the material to be joined while applying a tensile force between the welding pin and the material to be joined, and the welding pin and the material to be joined are subjected to a predetermined inspection current. Stud welding is characterized by including an inspection step of detecting the presence or absence of separation between the weld pin and the welded material by softening the welded portion with the welded material and detecting a welded pin with poor welding. Method. The welding gun is provided with a magnet capable of attracting and holding the welding pin, and the welding gun is pulled away from the material to be joined in a state where the welding pin is held by the magnet. The stud welding method according to claim 1, wherein the tensile force is generated between the welding pin and the material to be joined. While the welding current is energized under a state in which the welding pin is attracted and held by the magnet provided in the welding gun, the welding current is attracted and held by the magnet after the completion of the energization operation. Under the condition, the tensile force is generated by applying a force in the direction of separating the welding pin from the material to be joined, so that the inspection current is energized. The stud welding method according to claim 1 or 2, wherein the stud welding method is characterized. Claim 1 is characterized in that the material to be joined is a base steel plate, and the welding pin penetrated through a heat insulating material arranged so as to cover the base steel plate is welded to the base steel plate. The stud welding method according to any one of claims 3. By applying a predetermined welding current between the welding pin and the material to be joined, a stud welding device is used so that the tip of the welding pin is welded to the material to be welded.
A gun shaft arranged and supported in the gun body, a power feeding plug attached to the tip of the gun shaft to attract and hold the welding pin with a magnet, and to energize the welding pin, and the gun shaft. A first trigger means for outputting a welding signal for passing a welding current in a state where the welding pin held by the power feeding plug attached to the tip of the welding pin is pressed against the material to be joined, and the welding pin. Under the holding state by the power feeding plug, a predetermined inspection current is applied to the welding pin and the welding material by the tensile force generated by the movement of the gun shaft in the direction away from the welding material with respect to the welding pin. It is equipped with a welding gun having a second trigger means for outputting an inspection signal for flowing between the two.
The welding pin is welded to the material to be joined by energizing the welding current between the welding pin and the material to be welded by the welding signal output from the first trigger means and causing arc discharge. The inspection current is energized between the welding pin and the material to be joined by the inspection signal output from the first energizing circuit and the second trigger means, and the welding pin and the material to be joined are brought into contact with each other. By softening the welded portion, it is further provided with a second energizing circuit for checking the presence or absence of separation between the weld pin and the material to be welded and detecting the weld pin with poor welding. Stud welding equipment. By applying a predetermined welding current between the welding pin and the material to be joined, the tip of the welding pin is welded to the material to be welded to obtain a method for inspecting a stud weld.
While applying a tensile force between the welding pin and the material to be joined in the stud welded product, a predetermined inspection current is applied between the welding pin and the material to be joined, and the welding pin and the material to be joined are energized. A method for inspecting stud welds, which comprises detecting the presence or absence of separation between the weld pin and the material to be joined by softening the welded portion with and the weld pin, and detecting a weld pin with poor welding.

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