JPH11192551A - Method for predicting progression of disconnection of secondary cable strand for welding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to check the deterioration of a secondary cable or connector and to make remedy, such as early exchange, by emitting a display and alarm when the short-circuit voltage increment of the N-th time exceeds the permissible value of a resistance increase voltage drop. SOLUTION: A permissible value ΔRr of the resistance increase from the resistance value at the section and length of the connected secondary cable to the resistance value to give rise to the danger of an overheat burn is set before the start of work. The short-circuit current after a stud is pushed into a material to be welded is supplied at the time of first welding at the start of the work and the average value V2a=V21 of the pushing short-circuit current and the average value I2a=I21 of the pushing short-circuit current are detected. The initial resistance value R1=V21/I21 is then calculated. The average value V2a=V2n of the pushing short-circuit current and the average value I2a=I2n of the pushing short-circuit current are detected and Rn=V 2n/I2n is calculated during the supply of the short-circuit current of the N-th time. The resistance value increment ΔRn=Rn-R1 of the N-th time is then determined and is compared with ΔRr. The point of the time that ΔRn exceeds ΔRr is determined as the time for exchange of the secondary cable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixed part of a cable (hereinafter referred to as a main body cable) or a main body cable attached to a main body of a stud welding gun or a semi-automatic gas shield consumable electrode arc welding torch. The present invention relates to a method for predicting the progress of disconnection of a welding cable strand to be extendedly connected to a cable.

[0002]

2. Description of the Related Art First, a main body cable and a welding cable (hereinafter referred to as a secondary cable) are frequently routed to a welded portion, bent and extended, as compared with a normal fixedly wired cable. (Hereinafter, referred to as the number of bending times) and the twisting of the secondary cable is large, so that the cable strand is often disconnected (hereinafter, referred to as partial disconnection). Second, since the main body cable uses a thinner wire than a normal cable in order to improve flexibility, the wire is easily broken. Third, since the wire is frequently moved to the welded portion and a large current is applied, compared to a fixedly wired cable, a cable having a smaller cross-sectional area is used. When a part of the wire breaks, the remaining wire breaks rapidly. Therefore, the deterioration of ordinary fixed-wired cables deteriorates insulation due to the heat generated by the voltage drop, making them unusable. On the other hand, the deterioration of secondary cables is abnormal due to the progression of wire breakage. It becomes unusable due to overheating.

[0004] In particular, in a stud welding operation for a large structure such as a building where a welding portion is to be welded, a welding cable is connected and extended to a main body cable up to the welding portion, and the total extension length is 100 [m]. There is also. The secondary cable is frequently routed to the welding location. In particular, the main body cable has a large number of bendings, and is partially broken when used repeatedly, and the number of the partially broken wires progresses rapidly.

Further, stud welding is performed at 1000 [A].
Since the above large current flows, even if the secondary cable has a small resistance value, a considerably large voltage drop of about 10 to 30 [V] occurs, and the secondary cable generates heat. In the part where the number of times is large, the deterioration of the secondary cable is severe, and the number of partial breaks progresses rapidly during welding work, which may cause arcs in the partial breaks, which is dangerous. Since the portion where the number of times of bending of the secondary cable is large is located near the welding operator, a burn accident has actually occurred in some cases. Therefore, it is necessary to check the disconnection of the welding cable strand and the progress of the number of partial disconnections thereof (hereinafter referred to as disconnection check) periodically or before starting the welding operation.

[0010] The present applicant has applied a constant current to the secondary cable itself as a countermeasure against an accident that actually occurred in the stud welding (check for disconnection of the secondary cable).
A method for confirming a temperature rise in a portion to be checked for disconnection was examined. Hereinafter, a method for checking the broken connection of the secondary cable will be described.

FIG. 1 is a view showing a connection state of a secondary cable when ordinary stud welding is performed. Normally, one end of the main body cable 17a of the welding gun 2 has a main body cable connection fitting 2 attached to a stud moving shaft 2a for moving a stud chuck 2b holding a stud S.
c. When performing normal stud welding, the other end of the main body cable 17a of the welding gun 2 is connected to one output terminal of the welding power supply 1, and the welding cable 17 is connected to the workpiece W and the welding power supply 1. Between the other output terminals.

FIG. 2 is a diagram showing a connection state of the secondary cable when checking the deterioration state of the secondary cable of the stud welding according to the conventional method of the present applicant. In this disconnection checking method, the life of the secondary cable is determined when half of the number of the secondary cables is disconnected. In the figure, a constant current is supplied to the secondary cable 17 by using a normal stud welding power supply 1. When checking the deterioration state of the main body cable 17a, the main body cable 17a connected to the main body cable connection fitting 2c is removed from the state of FIG. 1 and is connected to one output terminal of the welding power supply device 1. Connect to welding cable 17. The temperature rise value of the disconnection check portion 17b of the main body cable 17a to be checked for disconnection is measured in advance using a temperature rise value measuring device 31 using a thermocouple 32 or the like, and this initial temperature rise value is determined as a judgment temperature. The rising value Tr is used.

Next, actually, a cycle of 1 second energization corresponding to the stud welding current and a 5 second pause is approximately 15 cycles.
A current of 00 [A] is applied. 20 cycles and 100
During the energization of the cycle (hereinafter, referred to as Nth cycle), the temperature rise value of the disconnection check portion 17b after the end of welding is measured using the temperature rise value measuring device 31 and determined as the Nth measured temperature rise value Tn. The life is estimated by comparing the temperature rise value Tr.

[0020]

In the conventional method of the present applicant, a bent portion where disconnection is likely to occur, for example, a disconnection check portion 17b in FIG. 2 is specified, and the temperature of the specified disconnection check portion 17b is determined. Since the rising value has to be measured using the thermocouple 32 or the like, a considerable amount of labor is required, and it is not practical especially for work at a construction site. Further, since errors and variations occur at the time of measuring the temperature of the specified portion, this considered disconnection check method must always be used in combination with the check of the coating appearance of the secondary cable.

[0031]

According to a first aspect of the present invention, there is provided a method for checking deterioration of a secondary cable, wherein a cross-section of a secondary cable (judgment reference secondary cable) connected before starting work. The resistance increase voltage drop allowable value ΔVr from the resistance value at the length to the resistance value causing the danger of overheating burnout is determined in advance, and a short-circuit current is supplied during the first welding at the start of work, and the short-circuit voltage average value V2a = V21 (Hereinafter, referred to as an initial short-circuit voltage average value V21), and then a short-circuit current is supplied at each welding, for example, at the time of the N-th welding, and an N-th short-circuit voltage average value V21 is applied.
2a = V2n (hereinafter referred to as an N-th short-circuit voltage average value V2n), and an N-th short-circuit voltage increase ΔV2n of a difference between the N-th short-circuit voltage average value V2n and the first short-circuit voltage average value V21.
= V2n-V21, and the Nth short-circuit voltage increase ΔV
2n and the above-mentioned resistance increase voltage drop allowable value ΔVr,
This is a method for predicting the progress of the disconnection of a secondary wire for welding at the time when the N-th short-circuit voltage increase ΔV2n exceeds the resistance increase voltage drop allowable value ΔVr.

According to a second aspect of the present invention, in the method for checking the deterioration of the secondary cable, the resistance from the cross section and the length of the secondary cable connected before the start of the operation to the resistance value which may cause overheating and burning. Resistance increase voltage drop ΔVr
In advance, at the time of the first welding at the start of the work, during the short-circuit current flow after pushing the stud into the workpiece, the initial indentation short-circuit voltage average value V2a = V21 is measured,
For each welding, for example, during the short-circuit current flow after pushing the stud into the material to be welded for the Nth time, the Nth indentation short-circuit voltage average value V2a = V2n is measured, and this Nth indentation short-circuit voltage average value V2a = V2n Above initial short-circuit voltage V
2a = N21th press-in short-circuit voltage increase ΔV2n difference from V21
= V2n-V21, and compares the Nth press-in short-circuit voltage increase ΔV2n with the resistance increase voltage drop allowable value ΔVr, and calculates the Nth push-in short-circuit voltage increase ΔV2n as the resistance increase voltage drop allowable value ΔVr. This is a method for predicting the progress of disconnection of a secondary cable strand for welding, with the point in time beyond which the secondary cable is replaced.

According to a third aspect of the present invention, in the method for checking the deterioration of a secondary cable, from the resistance value in the cross section and the length of the secondary cable connected before the start of the operation to the resistance value causing a danger of overheating and burning. Is set in advance, and the Nth resistance value increase ΔRn = Rn−R1 of the difference between the initial resistance value R1 at the time of initial welding at the start of work and the Nth resistance value Rn at the time of Nth welding. Is calculated, and the N-th resistance increase ΔRn is compared with the resistance increase allowable value ΔRr, and the time when the N-th resistance increase ΔRn exceeds the resistance increase allowable value ΔRr is determined. This is a method for predicting the progress of disconnection of a secondary cable strand for welding to be replaced.

According to a fourth aspect of the present invention, in the method for checking the deterioration of a secondary cable, from the resistance value in the cross section and the length of the secondary cable connected before the start of the operation to the resistance value causing a risk of overheating and burning. Is set in advance, and a short-circuit current is supplied during the first welding at the start of the work, and the short-circuit voltage average value V2a = V21 and the short-circuit current average value I2a =
I21 is detected to calculate an initial resistance value R1 = V21 / I21. Then, a short-circuit current is supplied at each welding, for example, at the time of the Nth welding, and an Nth short-circuit voltage average value V2a = V2n and a short-circuit current average value I2a = I2n is detected and the Nth resistance value Rn = V2n /
I2n is calculated, and the Nth resistance value increase ΔRn = Rn−R1 of the difference between the Nth resistance value Rn and the initial resistance value R1 is calculated.
Is calculated, and the N-th resistance increase ΔRn is compared with the resistance increase allowable value ΔRr, and the time when the N-th resistance increase ΔRn exceeds the resistance increase allowable value ΔRr is determined by 2
This is a method for predicting the progress of disconnection of a secondary cable strand for welding at the time of replacing the next cable.

According to a fifth aspect of the present invention, in the method for checking the deterioration of a secondary cable, from the resistance value in the cross section and the length of the secondary cable connected before the start of the operation to the resistance value causing a risk of overheating and burning. The resistance increase allowable value ΔRr is determined in advance, and at the time of the first welding at the start of the work, the short-circuit voltage average value V2a = V21 when the short-circuit voltage average value V2a = V21 during the short-circuit current after the stud is pushed into the workpiece. Average value I
2a = I21 is detected and the initial resistance value R1 = V21 / I21 is calculated. Then, during the welding, for example, when the short-circuit current is applied after the stud is pushed into the work to be welded at the Nth time, the average of the pushing short-circuit voltage is obtained. Value V2a = V2n and the average value of the inrush short-circuit current I2a = I
2n is detected and the Nth resistance value Rn = V2n / I2n is calculated, and the Nth resistance value increase ΔRn = Rn−R1 of the difference between the Nth resistance value Rn and the initial resistance value R1 is calculated. The Nth resistance value increase ΔRn and the resistance increase allowable value ΔR
When the N-th resistance increase ΔRn exceeds the resistance increase allowable value ΔRr, the time at which the secondary cable is replaced is determined by the method of predicting the progress of the disconnection of the secondary cable strand for welding. is there.

According to a sixth aspect of the present invention, in the method for checking the deterioration of the secondary cable, from the resistance value in the cross section and the length of the secondary cable connected before the start of the operation to the resistance value that may cause overheating and burning. , A short-circuit current is supplied during the first welding at the start of the work, and during the initial short-circuit detection period Tsd, the short-circuit voltage instantaneous value V (t) and the short-circuit current The instantaneous resistance value R (t) = V (t) / I (t) is calculated by detecting the value I (t) and dividing the short-circuit voltage instantaneous value V (t) by the short-circuit current instantaneous value I (t). The instantaneous resistance value R (t) is accumulated to calculate the initial resistance value R1 during the initial short-circuit detection period Tsd. During the period Tsd, the short-circuit voltage instantaneous value V (t) and the short-circuit current instantaneous value I (t) at time t Detecting a short-circuit voltage instantaneous value V
(T) is divided by the instantaneous short-circuit current value I (t) to calculate an instantaneous resistance value R (t) = V (t) / I (t), and this instantaneous resistance value R (t) is accumulated. , The accumulated resistance value Rnt within the Nth short-circuit detection period Tsd is calculated, and the short-circuit voltage instantaneous value V
For each detection of (t) and the instantaneous short-circuit current value I (t), the cumulative resistance increase ΔRnt = Rnt−R1 at the Nth welding of the difference between the cumulative resistance value Rnt and the initial resistance value R1 is calculated. ,
The accumulated resistance increase ΔRnt and the resistance increase allowable value ΔR
When the cumulative resistance value increase ΔRnt exceeds the resistance increase allowable value ΔRr, the welding current is cut off or a secondary cable replacement time is displayed. This is a method for predicting the progress of the disconnection of the next cable strand.

According to a seventh aspect of the present invention, in the method for checking deterioration of a secondary cable, from a resistance value in a cross-section and a length of a secondary cable connected before starting work to a resistance value causing a danger of overheating and burning. The resistance increase allowable value ΔRr is determined in advance, and at the time of the first welding at the start of the work, the push-in short-circuit at time t during the push-in short-circuit detection period Tsd during the current application of the short-circuit current after the stud is pushed into the workpiece. The instantaneous voltage value V (t) and the instantaneous pushing short-circuit current I (t) are detected, and the instantaneous pushing short-circuit voltage value V (t) is divided by the instantaneous pushing short-circuit current value I (t) to obtain an instantaneous resistance value R ( t) = V
(T) / I (t) is calculated, and this instantaneous resistance value R (t) is calculated.
Is accumulated to calculate the initial resistance value R1 of the initial short-circuit detection period Tsd, and then the indentation short-circuit detection period Tsd during energization of the short-circuit current after the stud is pushed into the material to be welded, for example, every Nth time. , The instantaneous value of the inrush short-circuit voltage V at time t
(T) and the instantaneous pushing short-circuit current value I (t) are detected, and the instantaneous pushing short-circuit voltage value V (t) is divided by the instantaneous pushing short-circuit current value I (t) to obtain an instantaneous resistance value R (t) = V.
(T) / I (t) is calculated, and this instantaneous resistance value R (t) is calculated.
Is accumulated, and the accumulated resistance value R within the Nth short-circuit detection period Tsd is calculated.
nt, and each time the short-circuit voltage instantaneous value V (t) and short-circuit current instantaneous value I (t) are detected, the cumulative resistance at the time of N-th welding of the difference between the cumulative resistance value Rnt and the initial resistance value R1 is calculated. The value increase ΔRnt = Rnt−R1 is calculated, and the cumulative resistance increase ΔRnt is compared with the resistance increase allowable value ΔRr. When the cumulative resistance Rnt exceeds the resistance increase allowable value ΔRr, This is a method for predicting the progress of the disconnection of the secondary cable for welding, which interrupts the welding current or indicates the time to replace the secondary cable.

According to a eighth aspect of the present invention, in the method for checking deterioration of the secondary cable, a new secondary cable may be used at the time of maintenance inspection of the deterioration check of the secondary cable or at the start of any welding work.
The reference resistance value Rs of the cable is measured or calculated in advance, and the allowable resistance value change δR from the resistance value in the cross section and the length of the new secondary cable to the resistance value that may cause overheating burnout is determined in advance. In advance, the initial resistance value R1 of the secondary cable which is not new is calculated and compared with the reference resistance value Rs. The absolute value | R1-Rs | This is a method of predicting the progress of the disconnection of a secondary cable strand for welding at a point in time when the secondary cable is replaced.

In the method for checking the deterioration of the secondary cable, a new secondary cable may be used at the time of maintenance and inspection of the deterioration check of the secondary cable or at the start of an arbitrary welding operation.
The reference resistance value Rs of the cable is measured or calculated in advance, and the allowable resistance value change δR from the resistance value in the cross section and the length of the new secondary cable to the resistance value that may cause overheating burnout is determined in advance. The short circuit voltage average value V2a = V21 and the short circuit current average during the periodic inspection of the deterioration check of the secondary cable or when the short circuit current is applied at the start of an arbitrary welding operation using a new secondary cable. Detecting the value I2a = I21, calculating the initial resistance value R1 = V21 / I21, comparing the calculated resistance value with the reference resistance value Rs, and calculating the absolute value | R1-Rs |
Is a method for predicting the progression of disconnection of a secondary cable for welding, with the time when the resistance value change allowable value δR is exceeded being the time for replacing the secondary cable.

A method according to a tenth aspect of the present invention is the secondary cable deterioration checking method, wherein a judgment reference resistance value Rs of a new secondary cable is determined at the time of maintenance inspection of the deterioration check of the secondary cable or at the start of an arbitrary welding operation. Is measured or calculated in advance, and a resistance change allowable value δR from a resistance value in a cross section and a length of a new secondary cable to a resistance value causing a danger of overheating burnout is determined in advance, and the secondary cable which is not new is determined. During the short-circuit current flow after the stud is pushed into the workpiece by using a cable, the average push-in short-circuit voltage value V2a = V21 and the average push-in short-circuit current value I2a = I21 are detected, and the initial resistance value R1 is set. = V21 / I21, and the above-described determination reference resistance value Rs
When the absolute value | R1−Rs | of the difference exceeds the resistance change allowable value δR, the method of predicting the progress of the disconnection of the secondary cable for welding is used as the time to replace the secondary cable. is there.

According to a eleventh aspect of the present invention, in the method for checking the deterioration of a secondary cable, the judgment reference resistance value Rs of a new secondary cable is measured or calculated in advance at the start of welding work, and the new secondary cable is measured. A resistance change allowable value δR from a resistance value in a section and a length of the cable to a resistance value causing a danger of overheating burnout is determined in advance, and a non-new secondary cable is used for each welding, for example, N The second resistance value Rn is calculated and compared with the above-described determination reference resistance value Rs, and the time when the absolute value | Rn−Rs | of the difference exceeds a predetermined resistance value change allowable value δR is determined when the secondary cable is replaced. 2 for welding
This is a method for predicting the progress of the disconnection of the next cable strand.

According to a twelfth aspect of the present invention, in the method for checking deterioration of a secondary cable, a judgment reference resistance value Rs of a new secondary cable is measured or calculated in advance at the start of welding work, and a new secondary cable is measured. A resistance change allowable value δR from a resistance value in a section and a length of the cable to a resistance value causing a danger of overheating burnout is determined in advance, and a non-new secondary cable is used for each welding, for example, N During the energization of the short-circuit current, the average N-th short-circuit voltage V2a = V2n and the average short-circuit current I2a = I2n are detected, and the N-th resistance Rn = V2n / I2n
Is calculated and compared with the determination reference resistance value Rs. The time when the absolute value | Rn−Rs | of the difference exceeds the resistance value change allowable value δR is used as the welding time for the secondary cable replacement.
This is a method for predicting the progress of the disconnection of the next cable strand.

According to a thirteenth aspect of the present invention, in the method for checking the deterioration of the secondary cable, the judgment reference resistance value Rs of the new secondary cable at the time of maintenance inspection of the deterioration check of the secondary cable or at the start of an arbitrary welding operation. Is measured or calculated in advance, and a resistance change allowable value δR from a resistance value in a cross section and a length of a new secondary cable to a resistance value causing a danger of overheating burnout is determined in advance, and the secondary cable which is not new is determined. Each time the stud is pushed into the material to be welded using a cable,
For example, during the N-th short-circuit current conduction, the N-th indentation short-circuit voltage average value V2a = V2n and the indentation short-circuit current average value I2a
= I2n and the Nth resistance value Rn = V2n / I2n is calculated and compared with the determination reference resistance value Rs, and the absolute value | Rn−Rs | of the difference exceeds the resistance value change allowable value δR. This is a method for predicting the progress of disconnection of a secondary cable strand for welding, with the time point when the secondary cable is replaced.

The method according to claim 14 is a method according to claim 8 or claim 9 or claim 10 or claim 11 or claim 12 or claim 13 wherein the reference resistance value Rs of a new secondary cable is determined.
The following is a method for predicting the progress of the disconnection of the secondary wire for welding, which is the resistance value calculated from the diameter Ds of the secondary cable and the total length Ls of the secondary cable.

A method according to claim 15 is a method for determining a reference resistance Rs of a new secondary cable according to claim 8 or claim 9 or claim 10 or claim 11 or claim 12 or claim 13.
Is the sum of the total cable resistance calculated from the diameter Ds of the secondary cable and the total length Ls of the secondary cable, the total contact resistance of the product of the contact resistance at one connection point and the number of connection points. This is a method of predicting the progress of disconnection of a secondary cable strand for welding, which is a sum.

According to a sixteenth aspect of the present invention, in the secondary cable deterioration checking method, a variation in the calculated resistance value Ra of the secondary cable calculated after the start of welding is detected, and the variation in the calculated resistance value Ra is determined in advance. This is a method of predicting the progress of disconnection of a secondary cable strand for welding, in which a point in time when the calculated resistance fluctuation allowable value ΔRm is exceeded is set as a time to replace the secondary cable.

According to a seventeenth aspect of the present invention, in the method for checking the deterioration of a secondary cable, from the resistance value in the cross section and the length of the secondary cable connected before the start of the operation to the resistance value causing a risk of overheating and burning. Is calculated in advance, and the calculated resistance maximum fluctuation value (Rma-Rm) of the difference between the calculated resistance maximum value Rma and the calculated resistance minimum value Rmi after the start of welding is determined.
Rmi) exceeds the calculated resistance variation allowable value ΔRm,
This is a method for predicting the progress of disconnection of a secondary cable strand for welding when the secondary cable is to be replaced.

In a method for checking the deterioration of a secondary cable, the method according to the present invention provides a method for checking the deterioration of a secondary cable, from a resistance value in a cross-section and a length of a secondary cable connected before starting a work to a resistance value causing a risk of overheating and burning. The resistance change allowable value ΔRm is determined in advance, and a short-circuit current is supplied at each welding, for example, at the time of the Nth welding, and an Nth short-circuit voltage average value V2a = V2n and a short-circuit current average value I2a = I2n are detected. Nth resistance value Rn =
By calculating V2n / I2n, the N-th resistance value Rn becomes (N-1)
The calculated resistance maximum value Rma or the calculated resistance minimum value Rmi up to the first time
Is exceeded, the N-th resistance value Rn is set to the calculated resistance maximum value Rma or the calculated resistance minimum value Rmi up to the (N-1) th time, and the N-th calculated resistance maximum value Rma and the calculated resistance minimum value after the start of welding. Calculation of the difference with Rmi Maximum resistance fluctuation value (Rma-Rmi)
Is a method of predicting the progress of the disconnection of the secondary cable for welding, with the time when the calculated resistance variation allowable value ΔRm is exceeded as the replacement time of the secondary cable.

[0049]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the above-described method for checking the disconnection of the secondary cable for welding according to the present invention, the temperature of the wire breakage portion increases as the energizing time elapses and the number of disconnections of the secondary cable increases. Is significantly increased, the resistance of the secondary cable including the broken wire is increased. (1) Therefore, before the start of the work, the allowable resistance increase ΔRr from the resistance value in the cross section and the length of the connected secondary cable to the resistance value causing the danger of overheating and burning is determined in advance. (2) During the first welding at the start of the work, during the short-circuit current application after the stud is pushed into the workpiece, the average indentation short-circuit voltage V2a = V21 and the average indentation short-circuit current I2a = I
21 to calculate the initial resistance value R1 = V21 / I21. (3) Next, during the short-circuit current flow after the stud is pushed into the material to be welded, for example, at the N-th welding, the short-circuit voltage average value V2a = V2n and the short-circuit current average value I2a = I
2n is detected and the Nth resistance value Rn = V2n / I2n is calculated. (4) Calculate an Nth resistance value increase ΔRn = Rn−R1 of a difference between the Nth resistance value Rn and the initial resistance value R1. (5) The N-th resistance increase ΔRn is compared with the resistance increase allowable value ΔRr to obtain the N-th resistance increase ΔR.
This is a method for predicting the progress of the disconnection of the secondary wire for welding, which is displayed or warned to the operator when n becomes larger than the allowable resistance increase value ΔRr.

[0050]

FIG. 3 is a block diagram of a stud welding apparatus having a secondary cable disconnection check function according to the present invention. The stud welding apparatus shown in FIG.
And a welding control device 3. The welding power supply device 1 outputs a welding current consisting of a pilot current Ip and a main arc current Ia to a welding gun 2, and in accordance with an analog signal output from a welding control device 3 described later, a welding current value Io. Command output circuit 5 for controlling the welding current, a welding current output circuit 15 composed of a semiconductor switching element such as a thyristor for controlling the welding current based on the current command, and a welding cable 2 attached to the welding gun 2 through the secondary cable 17. Stud S
A welding current detection circuit IC for detecting a welding current value Io output to the inverter and outputting a welding current detection signal Ic, and a welding voltage detection circuit VC for detecting an output terminal voltage value Vd and outputting a welding voltage detection signal Vc. Formed from

The welding control device 3 receives the welding current detection signal Ic
A / D converter 7 which converts a welding voltage detection signal Idd into a digital welding current detection signal Idd and outputs it to the arithmetic processing circuit CPU, and an A / D converter 7 which converts the welding voltage detection signal Vc into a digital welding voltage detection signal Vdd and outputs it to the arithmetic processing circuit CPU. A / D converter 8, an arithmetic processing circuit CPU which receives a digital welding current detection signal Idd and a digital welding voltage detection signal Vdd, and outputs a digital output signal to be described later, and converts a digital output signal Iod of the arithmetic processing circuit CPU into an analog signal. A D / A converter 6 for converting to an output signal Ioa and outputting it to a current command output circuit 5, a welding condition setting circuit 19 for setting welding conditions, a storage circuit 11 for storing set values, and an abnormality in a disconnection check result And an alarm device 12 (hereinafter, referred to as a display circuit) for displaying or alarming. The D / A converter 6, the A / D converter 7, and the A / D converter 8 may be built in the arithmetic processing circuit CPU.

The operation of the secondary cable disconnection check method will be described below with reference to the block diagram of the embodiment shown in FIG. When the tip of the stud S held by the welding gun 2 is pressed against the workpiece W and the welding start / end switch 13 of the welding gun 2 is pressed, the stud S at the pressed position is pressed.
Is raised to a preset position, and then a preset pilot current Ip is supplied. When the arc is generated by raising the stud, the pilot current Ip is switched to the main arc current Ia after a preset time. After a predetermined main arc period Ta elapses after reaching a required welding current value from the start of energization of the pilot current Ip or the main arc current Ia, the stud S is pushed toward the workpiece W. On the way, the stud S is short-circuited to the workpiece W, and the short-circuit current Is flows for the indentation short-circuit period Ts. In the series of welding operations, during the sampling time (push short-circuit detection period) Tsd of the push short-circuit period Ts described later, the arithmetic processing circuit CPU detects the push-in short-circuit current average value I2a and the push-in short-circuit voltage average value V2a. . These procedures are shown in FIG. 4 below.

FIG. 4A is a welding current waveform diagram showing the waveform of the welding current value Io, and FIG. 4B is a diagram showing the waveform of the output terminal voltage Vd detected at the output terminal of the welding power supply device. FIG. 7C is a diagram showing the movement amount M of the stud tip. The push-in short-circuit voltage instantaneous value V (t) is accumulated during the push-in short-circuit detection period Tsd from the push-in short-circuit voltage detection start time t91 to the push-in short-circuit voltage detection end time t9n,
By dividing by the indentation short-circuit detection period Tsd according to Equation 1, the indentation short-circuit voltage average value V2a is calculated.

[0072]

(Equation 1)

Similarly, the indentation short-circuit current instantaneous value I (t) is accumulated in the indentation short-circuit detection period Tsd, and the result is divided by the indentation short-circuit detection period Tsd according to Equation 2 to calculate the average indentation short-circuit current I2a.

[0076]

(Equation 2)

The indentation short-circuit voltage average value V2a calculated by the above equation (1) varies depending on differences in the length and diameter of the secondary cable related to the distance from the welding power source to the welding point, the resistance value of the material to be welded, and the like. It is the welding circuit voltage drop. In order to achieve the object of the present invention, as the voltage drop of the material to be welded is smaller than the voltage drop of the secondary cable, the disconnection check accuracy becomes higher.

Next, the resistance value Ra of the secondary cable during the press-in short-circuit detection period Tsd is calculated by dividing the above-described calculated press-in short-circuit voltage V2a by the press-in short-circuit current average value I2a. Hereinafter, Ra is referred to as a calculated resistance value. Ra = V2a / I2a (Equation 1)

The average indentation short-circuit voltage V2a calculated in the first welding at the start of the operation is V21, the average indentation short-circuit current I2a is I21, and the first calculated resistance value Ra at the start of the operation calculated by the equation 1 is the initial value. Assuming that the resistance value is R1, the initial resistance value R1 is as shown in Expression 2. R1 = V21 / I21 (Equation 2) The initial resistance value R1 is used as a reference value of the resistance value of the secondary cable.

Next, when the welding operation is started and the same secondary cable is used, the calculated resistance value Ra at the time of the Nth welding is calculated.
Is the N-th resistance value Rn, the N-th resistance value Rn is given by Equation 3.
It becomes as follows. Rn = V2n / I2n (Equation 3) At this time, the resistance value of Rn increases due to a rise in temperature due to the application of the welding current, and becomes larger than R1.

Assuming that the difference between the N-th resistance value Rn and the initial resistance value R1 is the N-th resistance value increase ΔRn, the N-th resistance value increase ΔRn is as shown in Equation 4. ΔRn = Rn−R1 (Equation 4)

The resistance value of the secondary cable differs depending on the length and diameter of the cable, and the temperature rise value of the secondary cable differs. The diameter of the secondary cable used in headed stud welding (φ16-22) is 80 [mm ² ] or 100 [m
m ² ], and in the field work, the temperature rise value of the secondary cable may reach 150 ° C. in some cases. Therefore, an allowable resistance increase value is defined as ΔRr according to the cable length and the diameter. For example, if the secondary cable length is 100 [m], Rr
Set to ₁₀₀ in advance. This ΔRr = Rr ₁₀₀ and the N
A comparison is made with the second increase in resistance value ΔRn.

When the Nth resistance value increase ΔRn is smaller than the resistance increase allowable value ΔRr, it is considered that heat is generated in the normal use range. However, when the Nth resistance value increase ΔRn is larger than the resistance increase allowable value ΔRr, it is considered that abnormal heat is generated. This abnormal heat generation is caused by using a secondary cable with a diameter smaller than the normal diameter.
Alternatively, the above-described bent portion is partially broken or a connection failure of a connector or the like occurs. At this time, the welding operation is stopped and the operator is notified of the secondary cable abnormality.

The arithmetic processing circuit CPU is an arithmetic processing circuit for executing the function shown in the flowchart of FIG. 5 described later by a digital signal, and is a digital welding voltage detection signal detected during the indentation short-circuit detection period Tsd as a reference. Vdd
And a digital welding current detection signal Idd, and a stud of a later-described indentation short-circuit detection period (sampling time) Tsd is pushed into the workpiece to be short-circuited. The digital welding voltage detection signal Vdd and the digital welding current detection signal Idd for the indentation short-circuit detection period Tsd were input, and the indentation short-circuit voltage average value V2a and the indentation short-circuit current average value I2a in the indentation short-circuit detection period Tsd described below were detected. later,
The calculated resistance value Ra is calculated by dividing the indentation short-circuit voltage average value V2a by the indentation short-circuit current average value I2a.
To memorize. Also, the calculated resistance value Ra is compared with a predetermined resistance increase allowable value ΔRr.

FIG. 5 is a flowchart showing a procedure for checking the increase in resistance of the secondary cable for each welding for predicting the progress of the disconnection of the secondary cable strand for welding. (1) Step ST1 is a step of generating a danger of overheating and burning from the resistance value in the cross section and the length of the connected secondary cable (hereinafter referred to as a criterion secondary cable) to the extent of a complete disconnection. This is a resistance increase allowable value setting step of setting the resistance increase allowable value ΔRr up to the value. (2) In step ST2, the stud is pushed into the work to be short-circuited by using a secondary cable for judgment criteria, and the short-circuit voltage average value V21 and the short-circuit current average value I21 are determined during the short circuit. This is an initial short-circuit voltage / current detection step to be detected. (3) Step ST3 is an initial resistance value calculating step of calculating the initial resistance value R1 by dividing the initial push-in short-circuit voltage average value V21 detected during the short-circuit current application by the initial push-in short-circuit current average value I21. (4) Step ST4 is a step 2 for judging stud welding.
In the next cable, the stud is pushed into the material to be welded to short-circuit, and the N-th short-circuit voltage average value V2n and the N-th short-circuit current average value I2n are detected while the short-circuit current is flowing. Step.

(5) In step ST5, the N-th resistance value Rn to be determined by dividing the indentation short-circuit voltage average value V2n detected during the short-circuit current conduction by the indentation short-circuit current average value I2n.
Is the Nth resistance value calculation step of calculating the resistance value. (6) Step ST6 is to subtract the initial resistance value R1 from the Nth resistance value Rn and determine the Nth resistance value increase Δ
This is a resistance value increase calculation step of calculating Rn = Rn-R1. (7) Step ST7 compares the Nth resistance increase ΔRn with a preset resistance increase allowable value ΔRr,
This is a determination resistance value comparison step of predicting the progress of the disconnection of the next cable strand. Display, warning, and the like can be performed by a signal obtained by comparing the Nth resistance value increase ΔRn and the resistance increase allowable value ΔRr.

Next, during the push-in short-circuit detection period Tsd, the push-in short-circuit voltage instantaneous value V (t) and the push-in short-circuit current instantaneous value I (t) at time t are detected, and the cumulative resistance value Rnt is calculated. The difference between the calculated cumulative resistance value Rnt and the initial resistance value R1 is the cumulative resistance value increase ΔNnt = Rnt− during the Nth welding.
A method of calculating R1 and interrupting the welding current when the cumulative resistance increase ΔRnt exceeds the resistance increase allowable value ΔRr will be described.

The procedure of this method is as follows. (1) First, before starting the operation, a resistance increase allowable value ΔRr from a resistance value in a cross section and a length of the secondary cable connected to a resistance value causing a danger of overheating and burning is determined in advance. (2) Next, a short-circuit current is supplied at the time of the first welding at the start of the work, and during the initial short-circuit detection period Tsd, the short-circuit voltage instantaneous value V (t) and the short-circuit current instantaneous value I (t) at time t are determined. To detect. (3) The instantaneous short-circuit voltage value V (t) is converted to the instantaneous short-circuit current value I.
The instantaneous resistance value R (t) is calculated by Equation 5 during the short circuit detection period Tsd from the short circuit voltage detection start time t91 to the short circuit voltage detection end time t9n. R (t) = V (t) / I (t) (Equation 5)

(4) The instantaneous resistance value R (t) is accumulated to calculate the initial resistance value R1 in the initial short-circuit detection period Tsd. (5) Next, a short-circuit current is supplied at the time of each welding, for example, at the time of the N-th welding, and during the N-th short-circuit detection period Tsd, the short-circuit voltage instantaneous value V (t) and the short-circuit current instantaneous value I (t) at time t. Is detected. (6) The instantaneous value of the short-circuit voltage V (t) is converted to the instantaneous value of the short-circuit current I
(T) divided by the instantaneous resistance value R (t) = V (t) / I
(T) is calculated. (7) This instantaneous resistance value R (t) is accumulated, and N is calculated from the short-circuit voltage detection start time t91 to the short-circuit voltage detection end time t9n.
The cumulative resistance value Rnt within the third short detection period Tsd is calculated. The arithmetic processing circuit CPU calculates the accumulated resistance value Rnt during the short-circuit detection period Tsd according to Equation 3.

[0116]

(Equation 3)

(8) Each time the short-circuit voltage instantaneous value V (t) and short-circuit current instantaneous value I (t) are detected, the cumulative resistance R
The difference between the nt and the initial resistance value R1 is calculated as an accumulated resistance value increase ΔRnt = Rnt−R1 at the Nth welding. (9) The accumulated resistance increase ΔRnt is compared with the resistance increase allowable value ΔRr, and when the cumulative resistance increase ΔRnt exceeds the resistance increase allowable value ΔRr, whether the welding current is interrupted, Alternatively, a display indicating the time of replacement of the secondary cable is displayed.

In the method for predicting the progress of disconnection of a secondary cable strand for welding according to the present invention, the welding condition setting circuit 1 is provided before the welding operation.
9, the initial resistance value R1 calculated at the time of the first welding or the judgment reference resistance value Rs of a new secondary cable is calculated by applying a short-circuit current at each welding after the second welding, for example, at the Nth welding. Is set as a reference value for comparison with the Nth resistance value Rn. If there is a change in the secondary cable length, the welding condition setting circuit 19 selects a preset value (secondary cable length, resistance increase allowable value ΔRr, etc.), and sets the resistance increase allowable value. ΔRr is set. Both of these use a new secondary cable first,
Although it is assumed that the resistance value increases due to aging or the like, it is not applicable when the resistance value decreases due to aging or the like.

Therefore, the initial resistance value R1 of the non-new secondary cable is modified and changed to the judgment reference resistance value Rs of the new secondary cable, and an arbitrary value when the secondary cable is not new is changed. After calculating the initial resistance value R1 at the start of the welding operation, the resistance value is compared with a judgment reference resistance value Rs of a new secondary cable, and the absolute value of the difference is determined by a predetermined resistance value change allowable value shown in Expression 6. If it exceeds δR, it indicates that the resistance value has changed significantly. δR <| R1-Rs | (Equation 6) The absolute value of the difference | R1-Rs |
When the value exceeds R, the operator can be notified by the display circuit 12.

A method of applying the judgment reference resistance value Rs of the new secondary cable will be described below. The first method is to measure or calculate a judgment reference resistance value Rs of a new secondary cable in advance at the time of maintenance inspection of the deterioration check of the secondary cable or at the start of an arbitrary welding operation, and at the same time, to measure a new secondary cable. A resistance change allowable value δR from a resistance value in a section and a length of the cable to a resistance value causing a danger of overheating burnout is determined in advance, and an initial resistance value R1 of a non-new secondary cable is calculated. The absolute value | R1−Rs | of the difference is compared with a determination reference resistance value Rs and a predetermined resistance value change allowable value δR
This is a method for predicting the progress of disconnection of a secondary cable strand for welding, with the point in time beyond which the secondary cable is replaced.

[0124] The second method is to carry out a new 2
The judgment reference resistance value Rs of the next cable is measured or calculated in advance, and the resistance change allowable value δR from the resistance value in the cross section and the length of the new secondary cable to the resistance value that may cause overheating burnout. Is determined in advance and the secondary
The average short-circuit voltage V2a = V21 and the average short-circuit current I2a = I21 are detected during the periodic inspection of the deterioration check of the secondary cable or at the start of any welding work using the cable during the short-circuit current supply. The initial resistance value R1 = V21 / I21 is calculated and compared with the determination reference resistance value Rs, and the absolute value | R1-
Rs | exceeds the resistance change allowable value δR,
This is a method for predicting the progress of disconnection of a secondary cable strand for welding at the time of replacing the next cable.

The third method is to use a new 2
The judgment reference resistance value Rs of the next cable is measured or calculated in advance, and the resistance change allowable value δR from the resistance value in the cross section and the length of the new secondary cable to the resistance value that may cause overheating burnout. Is determined in advance and the secondary
The short-circuit voltage average value V2a = V21 during the short-circuit current flow after the stud is pushed into the material to be welded using a stud.
And the average indentation short-circuit current value I2a = I21, calculate the initial resistance value R1 = V21 / I21, compare the calculated resistance value with the reference resistance value Rs, and determine the absolute value | R1-Rs | This is a method for predicting the progress of the disconnection of a secondary cable strand for welding, in which the point in time when the change exceeds the allowable change value δR is the time for replacing the secondary cable.

A fourth method is to measure or calculate a judgment reference resistance value Rs of a new secondary cable in advance at the time of starting a welding operation, and to determine a resistance value in a cross section and a length of the new secondary cable. The allowable value δR of the resistance change from the temperature to the resistance value causing the danger of overheating burnout is determined in advance, and a non-new secondary cable is used to calculate the Nth resistance value Rn for each welding, for example, and the above determination is made. The absolute value | Rn−Rs | of this difference is compared with a reference resistance value Rs, and a predetermined resistance value change allowable value δR
This is a method for predicting the progress of disconnection of a secondary cable strand for welding, with the point in time beyond which the secondary cable is replaced.

A fifth method is to measure or calculate a judgment reference resistance value Rs of a new secondary cable in advance at the time of starting a welding operation, and to determine a resistance value in a cross section and a length of the new secondary cable. The allowable value δR of the resistance change from the temperature to the resistance value causing the danger of overheating burnout is determined in advance, and the N-th time is used for each welding, for example, during the N-th short-circuit current application, using a non-new secondary cable. Detecting the short circuit voltage average value V2a = V2n and the short circuit current average value I2a = I2n, the Nth resistance value Rn = V2n /
I2n is calculated and compared with the judgment reference resistance value Rs. The absolute value | Rn-Rs |
This is a method for predicting the progress of disconnection of a secondary cable strand for welding, with the point in time beyond which the secondary cable is replaced.

The sixth method is to measure or calculate the judgment reference resistance value Rs of a new secondary cable in advance at the time of maintenance inspection of the deterioration check of the secondary cable or at the start of an arbitrary welding operation. The resistance change allowable value δR from the resistance value in the cross section and the length of the secondary cable to the resistance value causing the risk of overheating and burning is determined in advance, and the stud is used by using a non-new secondary cable. Is pushed into the workpiece, for example, during the N-th short-circuit current application, the N-th indentation short-circuit voltage average value V2a = V2n and the indentation short-circuit current average value I2a = I2n are detected, and the Nth resistance value Rn is detected. = V2n / I
2n is calculated and compared with the determination reference resistance value Rs. The time when the absolute value | Rn−Rs | of the difference exceeds the resistance value change allowable value δR is used as a time for replacing the secondary cable. This is a method for predicting the progress of disconnection of a secondary cable strand.

When a partial break occurs in the secondary cable, the resistance when the wire break is in contact as shown in FIG. -The abnormality of the bull cannot be determined. Therefore, depending on the state of the wiring or the like, the state shown in FIG.
Since a varies, the variation may be detected to predict the progress of the disconnection.

In this method, the connection is made before starting the work.
Calculated resistance change allowable value ΔRm from the resistance value at the cross section and length of the next cable to the resistance value causing danger of overheating
Is calculated in advance, and the calculated resistance maximum fluctuation value (Rma) of the difference between the calculated resistance maximum value Rma and the calculated resistance minimum value Rmi after the welding is started.
−Rmi) is a method of predicting the progress of the disconnection of the secondary cable strand for welding, with the time point when the calculated resistance variation allowable value ΔRm exceeds the secondary cable replacement time.

When the above-mentioned method is embodied, the calculated resistance variation allowable value ΔRm from the resistance value in the cross section and the length of the secondary cable connected before starting the operation to the resistance value causing the danger of overheating and burning is calculated. In advance, a short-circuit current is supplied at the time of each welding, for example, at the time of the N-th welding, and an N-th short-circuit voltage average value V2a = V2n and a short-circuit current average value I2a = I2n are detected.
When the N-th resistance value Rn exceeds the calculated resistance maximum value Rma or the calculated resistance minimum value Rmi up to the (N-1) th calculation, the N-th resistance value Rn is calculated.
n is the calculated resistance maximum value Rma or the calculated resistance minimum value Rmi up to the (N-1) th time, and the calculated resistance maximum fluctuation value of the difference between the Nth calculated resistance maximum value Rma and the calculated resistance minimum value Rmi after the start of welding ( (Rma-Rmi) exceeds the calculated resistance variation allowable value ΔRm, which is a method of predicting the progress of the disconnection of the secondary cable strand for welding, when the secondary cable is to be replaced.

[1000]

The common effects of the present invention are as follows. (1) First, the secondary cable is frequently routed to the welded portion and has a large number of bendings and twists as compared with a normal fixedly wired cable, so that the cable strand is disconnected (partial disconnection). Secondly, since the wires used are thinner than ordinary cables in order to improve the flexibility of the main body cable, the wires are liable to be broken. Since it is moved frequently and carries a large current, it uses a cable with a smaller cross-sectional area than a cable with fixed wiring, so the heat generation due to the voltage drop becomes large. Wire breakage progresses rapidly, resulting in abnormal heating and dangerous. In particular, when welding large structures such as buildings, connect the welding cable to the main body cable,
Extend to the welding point and move frequently, especially when
The bull has a large number of bendings, and the partial disconnection progresses rapidly after repeated use. On the other hand, in the present invention, the Nth resistance increase ΔRn of the difference between the initial resistance R1 at the time of initial welding at the start of the work and the Nth resistance Rn at the time of Nth welding.
Exceeds the allowable resistance increase ΔRr from the resistance value in the cross-section and length of the secondary cable connected before the start of the operation to the resistance value causing the danger of overheating, or calculation after the start of welding. The above-described problem is caused by replacing the secondary cable when the calculated maximum resistance change value (Rma−Rmi) of the difference between the maximum resistance value Rma and the minimum calculated resistance value Rmi exceeds the calculated resistance fluctuation allowable value ΔRm. Can be solved.

(2) In the present invention, a display or an alarm is output when the Nth resistance increase ΔRn exceeds a predetermined allowable resistance increase ΔRr, so that the secondary cable or connector is deteriorated. Can be confirmed, and measures such as early replacement can be taken. In addition, it can be recognized even when the available cable length is exceeded.

(3) In the present invention, the initial resistance value R1
Is displayed as exceeding a predetermined resistance value, for example, a judgment reference resistance value Rs, so that it can be known that the cable length exceeds the usable cable length.

(4) The effect of claim 1 is that when the external output characteristic of the welding power supply device is a constant current characteristic, in addition to the above-mentioned common effect of the present invention, an average value of the short-circuit voltage is calculated.
Since the change in the short-circuit voltage average value is automatically monitored, it is possible to predict the progress of disconnection of the secondary cable for welding with a simple device.

(5) The effect of claim 2 has the following effect in addition to the common effect of the present invention. In stud welding, a large current is usually passed through the secondary cable. Therefore, even if the secondary cable has a small resistance value, a large voltage drop occurs and the secondary cable generates heat. It is dangerous if the number of partial breaks progresses rapidly during welding work in a large number of parts and an arc is generated in the partially broken part. Burn accidents may occur due to the location. On the other hand, in the present invention, at the time of the first welding at the start of the work, the N-th indentation short-circuit voltage average value V2a = V2n and the initial in-push short-circuit voltage average during the short-circuit current flow after the stud was pushed into the workpiece. The difference between the value V2a = V21 and the Nth indentation short circuit voltage increase ΔV2n is from the resistance value in the cross section and the length of the secondary cable connected before the start of the operation to the resistance value that may cause overheating burnout. The above-mentioned problem can be solved by replacing the secondary cable when the resistance increase voltage drop allowable value ΔVr is exceeded. Furthermore, when the present invention is applied to stud welding, it is not necessary to supply the short-circuit current Is for the purpose of measuring the welding circuit voltage drop, and the welding circuit voltage drop can be measured during normal stud welding. A short circuit between the gun and the vicinity of the portion to be welded of the workpiece can be saved, and labor for measuring the welding circuit voltage drop can be omitted.

(6) In addition to the common effects of the present invention, the effect of claim 3 can be applied with high accuracy even when the external output characteristics of the welding power supply device are not constant current characteristics.

(7) In addition to the effect of the third aspect, the effect of the fourth aspect is that the secondary cable for checking for disconnection is short-circuited to the welding power supply device used for ordinary welding. The calculated resistance value can be calculated with high accuracy only by applying a current.

(8) The effect of claim 5 has the effect of claim 2 and claim 4.

(9) The effect of claim 6 is that every time the short-circuit voltage instantaneous value V (t) and the short-circuit current instantaneous value I (t) are detected, the difference between the cumulative resistance value Rnt and the initial resistance value R1 becomes Nth time. By calculating the cumulative resistance increase ΔRnt = Rnt−R1 at the time of welding, and when the cumulative resistance increase ΔRnt exceeds the resistance increase allowable value ΔRr, the welding current is cut off to thereby overheat and burn the secondary cable. Can be prevented with a margin.

(10) The effect of claim 7 has the effect of claim 2 and claim 6.

(11) The effect of claim 8 is that the effect is not new.
The initial resistance value R1 of the next cable is calculated and a new secondary cable is calculated.
And the absolute value of the difference |
When R1-Rs | exceeds the resistance change allowable value δR from the resistance in the cross section and the length of the new secondary cable to the resistance causing the danger of overheating, replace the secondary cable. First, the initial resistance value R1 of the non-new secondary cable is compared with the reference resistance value Rs of the new secondary cable. Second, the secondary cable replacement time can be predicted also at the time of maintenance inspection of the deterioration check of the secondary cable or at the start of an arbitrary welding operation.

(12) In addition to the effect of the eighth aspect, the effect of the ninth aspect is that the secondary cable for checking the disconnection is short-circuited to the welding power supply device used for ordinary welding. The calculated resistance value can be calculated with high accuracy only by applying a current.

(13) The effect of claim 10 has the effect of claim 2 and claim 9.

(14) The effect of claim 11 is that an N-th resistance value Rn is calculated by using a non-new secondary cable, and a criterion for determining a new secondary cable at the start of welding work. The absolute value of the difference | Rn−Rs |
However, by replacing the secondary cable when the resistance change allowable value δR from the resistance value in the cross section and the length of the new secondary cable to the resistance value causing the danger of overheating is exceeded, the secondary cable is replaced. The Nth resistance value Rn at the time of the Nth welding of a non-new secondary cable, as well as at the time of maintenance inspection of the deterioration check of the next cable or at the start of arbitrary welding work, is set to
Since the comparison is made with the judgment reference resistance value Rs of the next cable, it is possible to predict the result (replacement time of the secondary cable) based on the constant judgment criterion.

(15) The effect of claim 12 is the effect of claim 11
In addition to the effect of, the welding power supply used for normal welding,
The calculated resistance value can be accurately calculated only by short-circuiting the secondary cable to be checked for disconnection and supplying a short-circuit current.

(16) The effect of claim 13 has the effect of claim 2 and claim 12.

(17) The effect of claim 16 and claim 17 is that, when a partial break occurs in the secondary cable, and when the wire break portion is in contact as shown in FIG. Since the resistance value is normal, the progress of the partial disconnection of the secondary cable cannot be determined. Therefore, depending on the state of the wiring and the like, a state as shown in FIG. 6B is obtained. At this time, the calculated resistance value Ra varies, so that this variation is calculated and the progress of the disconnection of the welding secondary cable strand is calculated. Can be predicted.

(18) The effect of claim 18 has the effects of claims 2 and 17.

[Brief description of the drawings]

FIG. 1 is a view showing a connection state of a secondary cable when normal stud welding is performed.

FIG. 2 is a diagram showing a secondary cable for checking the deterioration state of a secondary cable of stud welding according to the conventional method of the present applicant.
It is a figure showing the connection state of a cable.

FIG. 3 is a diagram showing an embodiment of a stud welding apparatus for performing the method of the present invention.

FIG. 4A is a welding current waveform diagram showing a waveform of a welding current Io, and FIG. 4B is a diagram showing a waveform of an output terminal voltage Vd detected at an output terminal of the welding power supply device. Yes,
FIG. 9C is a diagram showing the movement amount M of the stud tip.

FIG. 5 is a flowchart of a method for managing heat input during a pulling-up period for calculating an equivalent arc voltage of stud welding according to the present invention.

FIG. 6A is a view showing a state in which a broken portion of the secondary cable is in contact with the secondary cable, and FIG. It is a figure showing a state.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 welding power supply device 2 welding gun 2 a stud moving shaft 2 b stud chuck 2 c body cable connection fitting 3 welding control device 5 current command output circuit 6 D / A converter 7, 8 A / D converter 11 storage circuit 12 display circuit or Alarm 13 Welding start / end switch 15 Welding current output circuit 16 Control cable 17 Secondary cable / Welding cable 17a Body cable / Secondary cable 17b to check for disconnection Disconnection check part of secondary cable 17a to check for disconnection 19 Welding condition setting circuit 31 Temperature rise value measuring device 32 Thermocouple CPU arithmetic processing circuit I2a (Push-in) average short-circuit current I21 Average short-circuit current during initial welding / Average short-circuit current during initial push-in I2n Average short-circuit current during Nth welding / Nth welding Inrush current average value Ia Main arc current IC Contact current detection circuit Ic Welding current detection signal Io Welding current / welding current value Ip Pilot current Is Tsd Average short-circuit current during pushing I (t) Instantaneous pushing short-circuit current M Movement amount of stud tip R1 Initial resistance value [V21 / I21] Ra calculated resistance value [V2a / I2a] Rma calculated resistance maximum value Rmi calculated resistance minimum value (Rma-Rmi) calculated resistance maximum fluctuation value ΔRm calculated resistance fluctuation allowable value Rn Nth resistance value [V2n / I2n] Rnt accumulation Resistance value ΔRnt Cumulative resistance value increase at Nth welding [Rnt-R
1] Rs (the new secondary cable) judgment reference resistance R (t) instantaneous resistance | R1-Rs | absolute value of difference between initial resistance and judgment reference resistance | Rn-Rs | Nth time Absolute value of difference between resistance value and judgment reference resistance value δR Resistance change allowable value causing danger of overheating and burning of secondary cable ΔRr Resistance increase allowable value ΔRn = Rn-R1 Nth increase in resistance value S Stud t9 (Push) Short circuit start time t10 (Push) Short circuit end time t91 (Push) Short circuit voltage detection start time t9n (Push) Short circuit voltage detection end time Ta Main arc period Tm Push period Tn Nth measured temperature rise value Tp Pilot Current period Tr Judgment temperature rise value Ts Push-in short-circuit period Tsd Push-in short-circuit detection period V2a (Push-in) Short-circuit voltage average value V21 Short-circuit voltage average value at the time of initial welding / Short-time of initial push-in Voltage average value V2n Short-circuit voltage average value at N-th welding / N-th press-in short-circuit voltage average value V2a Average (push-in) short-circuit voltage value during Tsd period VC Welding voltage detection circuit Vc Welding voltage detection signal Vd Output terminal voltage / output Terminal voltage value V (t) Instantaneous value of short-circuit voltage to be pushed in. ΔV2n Nth increase in short-circuit voltage [V2n-V21] ΔVr Allowable value of resistance increase voltage drop

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁶ Identification code FI B23K 11/24 337 B23K 11/24 337 31/00 31/00 Z

Claims (18)

[Claims] In a method for checking deterioration of a secondary cable, a resistance increasing voltage drop from a resistance value in a cross section and a length of a secondary cable connected before starting work to a resistance value causing a danger of overheating and burning. A permissible value is set in advance, a short-circuit current is applied at the first welding at the start of work, and a short-circuit voltage average value is measured. Then, at the Nth welding, a short-circuit current is applied and the Nth short-circuit voltage average value is measured. To calculate the N-th short-circuit voltage increase of the difference between the N-th short-circuit voltage average and the first short-circuit voltage average, and calculate the N-th short-circuit voltage increase and the resistance increase voltage drop allowable value. In comparison, a method for predicting the progress of disconnection of a secondary wire for welding is set such that a point in time when the N-th short-circuit voltage increase exceeds the resistance increase voltage drop allowable value is a secondary cable replacement time. 2. A method for checking deterioration of a secondary cable, comprising: increasing a voltage drop from a resistance value in a cross section and a length of a secondary cable connected before starting operation to a resistance value causing a danger of overheating and burning. The allowable value is determined in advance, and at the time of the first welding at the start of work, the average value of the initial pushing short-circuit voltage is measured during the short-circuit current flow after pushing the stud into the workpiece, and then the Nth stud During the short-circuit current flow after pushing into the workpiece, the N-th indentation short-circuit voltage average is measured, and the N-th indentation of the difference between the N-th indentation short-circuit voltage average and the first indentation short-circuit voltage average is performed. Calculate the short-circuit voltage increase and compare the N-th press-in short-circuit voltage increase with the resistance increase voltage drop allowable value. The N-th press-in short-circuit voltage increase exceeds the resistance increase voltage drop allowable value. A method for predicting the progress of the disconnection of a secondary cable strand for welding, with the time at which the secondary cable is replaced as the time of replacement. 3. A method for checking deterioration of a secondary cable, which is an allowable value of resistance increase from a resistance value in a cross section and a length of a secondary cable connected before starting work to a resistance value causing a risk of overheating and burning. Is calculated in advance, and the N-th resistance increase of the difference between the initial resistance at the first welding at the start of the work and the N-th resistance at the N-th welding is calculated, and the N-th resistance increase and the N-th resistance increase are calculated. Comparing with the resistance increase allowable value, the time when the Nth resistance value increase exceeds the resistance increase allowable value,
A method for predicting the progress of disconnection of a secondary cable strand for welding when the secondary cable is to be replaced. 4. A method for checking the deterioration of a secondary cable, which is an allowable resistance increase from a resistance value in a cross section and a length of a secondary cable connected before starting work to a resistance value causing a danger of overheating and burning. In advance, at the time of the first welding at the start of the work, a short-circuit current is supplied, a short-circuit voltage average value and a short-circuit current average value are detected, and an initial resistance value is calculated.
During the Nth welding, a short circuit current is applied to detect the Nth short circuit voltage average value and the short circuit current average value, calculate the Nth resistance value, and calculate the difference between the Nth resistance value and the initial resistance value. The N-th resistance increase is calculated, and the N-th resistance increase is compared with the resistance increase allowable value. The time when the N-th resistance increase exceeds the resistance increase allowable value is calculated as a secondary time. A method for predicting the progress of disconnection of a secondary cable strand for welding at the time of replacing a cable. 5. A method for checking the deterioration of a secondary cable, the allowable value of resistance increase from a resistance value in a cross section and a length of a secondary cable connected before starting work to a resistance value causing a danger of overheating and burning. At the time of the first welding at the start of work, the initial resistance is detected by detecting the average value of the short-circuit voltage and the average value of the short-circuit current during the short-circuit current flow after the stud is pressed into the workpiece. Then, during the N-th short-circuit current application after the stud is pushed into the workpiece, the N-th resistance value is calculated by detecting the average value of the short-circuit voltage and the average value of the short-circuit current. Calculating an N-th resistance increase in the difference between the N-th resistance and the initial resistance, comparing the N-th resistance increase with the allowable resistance increase, and calculating the N-th resistance. Increase exceeds the allowable resistance increase A method for predicting the progress of the disconnection of a secondary cable strand for welding, with the time at which the secondary cable is replaced as the time of replacement. 6. A method for checking deterioration of a secondary cable, which is an allowable resistance increase from a resistance value in a cross-section and a length of a secondary cable connected before starting work to a resistance value causing a risk of overheating and burning. The short-circuit current is supplied at the time of the first welding at the start of work, and the short-circuit voltage instantaneous value and the short-circuit current instantaneous value are detected during the initial short-circuit detection period. , The instantaneous resistance value is calculated, the instantaneous resistance value is accumulated, the initial resistance value during the initial short-circuit detection period is calculated, and then a short-circuit current is supplied during the N-th welding to detect the N-th short-circuit. During the period, the instantaneous value of the short-circuit voltage and the instantaneous value of the short-circuit current are detected, the instantaneous value of the short-circuit voltage is divided by the instantaneous value of the short-circuit current, the instantaneous resistance value is calculated, the instantaneous resistance value is accumulated, and the N-th short circuit is performed. The cumulative resistance value during the detection period is calculated, and the Each time the instantaneous pressure value and the instantaneous short-circuit current value are detected, the cumulative resistance increase at the N-th welding of the difference between the cumulative resistance and the initial resistance is calculated, and the cumulative resistance increase and the resistance increase are calculated. When the cumulative resistance increase exceeds the resistance increase allowable value, the welding current is cut off or a secondary cable replacement indication is displayed indicating that it is time to replace the secondary cable. A method for predicting the progress of cable breaks. 7. A method for checking deterioration of a secondary cable, which is an allowable resistance increase from a resistance value in a cross section and a length of a secondary cable connected before starting work to a resistance value causing a danger of overheating and burning. During the initial welding at the beginning of the work, the instantaneous value of the indentation short-circuit voltage and the instantaneous value of the indentation short-circuit current during the indentation short-circuit detection period during the energization of the short-circuit current after pushing the stud into the work piece Detect, calculate the instantaneous resistance by dividing the instantaneous value of the indentation short-circuit voltage by the instantaneous value of the indentation short-circuit current, accumulate the instantaneous resistance, calculate the initial resistance in the initial short-circuit detection period, , Detecting the instantaneous value of the indentation short-circuit voltage and the instantaneous value of the indentation short-circuit current during the indentation short-circuit detection period during the energization of the short-circuit current after pushing the stud into the material to be welded N times;
The instantaneous indentation short-circuit voltage value is divided by the instantaneous indentation short-circuit voltage value to calculate an instantaneous resistance value, the instantaneous resistance value is accumulated, and the accumulated resistance value in the Nth short-circuit detection period is calculated. Value and the instantaneous value of the short-circuit current, for each of the detections of the cumulative resistance value and the initial resistance value, calculate the cumulative resistance value increase at the Nth welding of the difference between the cumulative resistance value and the initial resistance value, and calculate the cumulative resistance value increase and the resistance increase allowable value. When the cumulative resistance exceeds the resistance increase allowable value, the welding current is interrupted,
Alternatively, a method of predicting the progress of disconnection of a secondary cable for welding, which indicates the time of replacement of the secondary cable. 8. A method for checking deterioration of a secondary cable, in which a reference resistance value of a new secondary cable is measured or calculated in advance at the time of maintenance check of the deterioration of the secondary cable or at the start of an arbitrary welding operation. In addition, an allowable resistance change value from a resistance value in a cross section and a length of a new secondary cable to a resistance value causing a danger of overheating and burning is previously determined, and an initial resistance value of a non-new secondary cable is determined. Is calculated and compared with the criterion resistance value, and the time when the absolute value of the difference exceeds a predetermined resistance value change allowable value is set as the secondary cable replacement time. Disconnection progress prediction method. 9. In the secondary cable deterioration checking method, a reference resistance value of a new secondary cable is measured or calculated in advance at the time of maintenance inspection of the secondary cable deterioration check or at the start of any welding work. At the same time, an allowable resistance change value from a resistance value in a cross section and a length of a new secondary cable to a resistance value causing a danger of overheating and burning is determined in advance, and a non-new secondary cable is used. During the periodical inspection of the deterioration check of the secondary cable or during the passage of the short-circuit current at the start of any welding work, the average value of the short-circuit voltage and the average value of the short-circuit current are detected to calculate the initial resistance value, The time at which the absolute value of the difference exceeds the allowable value of the resistance value change is regarded as the time for replacing the secondary cable.
How to predict the progress of disconnection of the next cable strand. 10. A method for checking deterioration of a secondary cable, wherein a judgment reference resistance value of a new secondary cable is measured or calculated in advance at the time of maintenance inspection of the deterioration check of the secondary cable or at the start of an arbitrary welding operation. With the new secondary case
The allowable value of the resistance change from the resistance value in the cross section and the length of the cable to the resistance value causing the risk of overheating and burning is determined in advance, and the stud is pushed into the material to be welded using a secondary cable which is not new. During the short-circuit current energization after that, the indentation short-circuit voltage average value and the indentation short-circuit current average value are detected to calculate an initial resistance value, compared with the determination reference resistance value, and the absolute value of the difference is the resistance value. The point at which the change allowable value is exceeded
A method for predicting the progress of disconnection of a secondary cable strand for welding at the time of replacing the next cable. 11. A method for checking the deterioration of a secondary cable, wherein, at the start of a welding operation, a reference resistance value for judging a new secondary cable is measured or calculated in advance, and a section and a length of the new secondary cable are measured. The allowable change in the resistance value from the resistance value to the resistance value causing the danger of overheating is determined in advance, and the N-th resistance value is calculated by using a non-new secondary cable to determine the N-th resistance value. The time when the absolute value of the difference exceeds a predetermined resistance value change allowable value,
A method for predicting the progress of disconnection of a secondary cable strand for welding at the time of replacing the next cable. 12. A method for checking the deterioration of a secondary cable, in which a reference resistance value of a new secondary cable is measured or calculated in advance at the start of a welding operation, and a cross section and a length of the new secondary cable are determined. The allowable change in the resistance value from the resistance value to the resistance value causing the danger of overheating and burning is determined in advance, and the N-th short-circuit is performed during the N-th short-circuit current application using a non-new secondary cable. A voltage average value and a short-circuit current average value are detected to calculate an N-th resistance value, which is compared with the determination reference resistance value. A method for predicting the progress of disconnection of a secondary cable strand for welding at the time of replacing a cable. 13. A method for checking the deterioration of a secondary cable, wherein a judgment reference resistance value of a new secondary cable is measured or calculated in advance at the time of maintenance and inspection of the deterioration check of the secondary cable or at the start of an arbitrary welding operation. With the new secondary case
The allowable value of the resistance change from the resistance value in the cross section and the length of the cable to the resistance value causing the risk of overheating and burning is determined in advance, and the stud is pushed into the material to be welded using a secondary cable which is not new. During the N-th short-circuit current conduction, the N-th push-in short-circuit voltage average value and the push-in short-circuit current average value are detected, the N-th resistance value is calculated and compared with the determination reference resistance value, and the absolute value of the difference is calculated. The time when the value exceeds the resistance change allowable value is the time for replacing the secondary cable.
How to predict the progress of disconnection of the next cable strand. 14. The method of claim 8 or claim 9 or claim 10.
Alternatively, the criterion resistance value of the new secondary cable according to claim 11 or 12 or 13 is a resistance value calculated from the diameter of the secondary cable and the total length of the secondary cable. A method for predicting the progress of disconnection of a secondary cable for welding. 15. The claim 8 or claim 9 or claim 10.
Alternatively, the reference resistance value of the new secondary cable according to claim 11, 12 or 13 is a total cable resistance calculated from the diameter of the secondary cable and the total length of the secondary cable. A method for predicting the progress of the disconnection of a secondary wire for welding, which is the sum of the value and the total contact resistance value of the product of the contact resistance value of one connection point and the number of connection points. 16. A method for checking deterioration of a secondary cable, comprising detecting a variation in a calculated resistance value of the secondary cable calculated after the start of welding, and determining that the variation in the calculated resistance value exceeds a predetermined calculated resistance variation allowable value. A method for predicting the progress of the disconnection of a secondary cable strand for welding, with the time at which the secondary cable is replaced as the time of replacement. 17. A method for checking deterioration of a secondary cable, which allows a change in resistance from a resistance value in a cross-section and a length of a secondary cable connected before starting work to a resistance value causing danger of overheating and burning. The value is determined in advance, and the time when the calculated resistance maximum fluctuation value of the difference between the calculated resistance maximum value and the calculated resistance minimum value after the start of welding exceeds the calculated resistance fluctuation allowable value,
A method for predicting the progress of disconnection of a secondary cable strand for welding when the secondary cable is to be replaced. 18. A method for checking deterioration of a secondary cable, which allows a calculated resistance to vary from a resistance value in a cross-section and a length of a secondary cable connected before starting work to a resistance value causing a danger of overheating and burning. A value is determined in advance, and a short-circuit current is supplied during the N-th welding, the N-th short-circuit voltage average value and the short-circuit current average value are detected, and the N-th resistance value is calculated.
When the Nth resistance value exceeds the calculated resistance maximum value or the calculated resistance minimum value up to the (N-1) th time, the Nth resistance value is reduced to the calculated resistance maximum value or the calculated resistance minimum value up to the (N-1) th time. For the welding of the secondary cable, the point at which the calculated resistance maximum fluctuation value of the difference between the N-th calculated resistance maximum value and the calculated resistance minimum value after the start of welding exceeds the calculated resistance fluctuation allowable value is used. The method for predicting the progress of the disconnection of the secondary cable strand.