JP6790050B2 - Resistance welding evaluation device and resistance welding evaluation method - Google Patents

Description

The present invention relates to a resistance welding evaluation device and a resistance welding evaluation method for evaluating whether or not spatter occurs when resistance welding is performed on a laminated portion of a plurality of materials to be welded.

For example, in Patent Document 1, when resistance welding is performed on a plurality of laminated portions of materials to be welded, it is possible to predict whether or not spatter will occur in the laminated portions based on the setting conditions of resistance welding. It is disclosed.

Japanese Patent No. 5217108

However, when simulating the presence or absence of spatter generation using the technique of Patent Document 1, it is necessary to finely divide a plurality of models of the material to be welded into a mesh. Therefore, the analysis time for predicting the presence or absence of spatter is long, which is not practical.

Further, in the simulation, it is necessary to preset the stress in the stacking direction (Z direction) of the corona bond portions generated in the laminated portions of the plurality of materials to be welded during resistance welding, which lacks versatility.

Furthermore, in simulation, it is difficult to predict the sputtering that occurs at the initial stage of energization, that is, when the nugget is not sufficiently grown.

The present invention has been made in consideration of such a problem, and a resistance welding evaluation device and a resistance welding evaluation method capable of easily and surely evaluating the presence or absence of spatter generation in a shorter analysis time. The purpose is to provide.

In the embodiment of the present invention, when resistance welding is performed on a laminated portion of a plurality of materials to be welded, spatter occurs based on the plate assembly conditions of the plurality of the materials to be welded and the setting conditions of the resistance welding. The present invention relates to a resistance welding evaluation device and a resistance welding evaluation method for evaluating whether or not.

In this case, the resistance welding evaluation device has a Joule calorific value calculation unit , a resistivity calculation unit, a threshold value setting unit, and an evaluation unit. The Joule calorific value calculation unit calculates the Joule calorific value generated in a plurality of the materials to be welded during the resistance welding based on the plate assembly conditions and the setting conditions. The resistivity ratio calculation unit calculates the ratio of the total resistance value of the plurality of the materials to be welded to the resistance value of the outer material to be welded, which has the thinnest plate thickness in the stacking direction among the plurality of the materials to be welded. Calculated as resistance ratio. The threshold setting unit performs principal component analysis on the upper limit of the Joule calorific value for each of the total plate thickness and the resistance ratio in the two-dimensional plane of the total plate thickness and the resistance ratio of the plurality of the materials to be welded in the stacking direction. The upper limit value of the Joule calorific value capable of performing the resistance welding without generating the spatter by using the first principal component axis obtained by the principal component analysis and the plurality of the upper limit values. Is set as the calorific value threshold. The evaluation unit compares the Joule calorific value threshold set by the threshold value setting unit with the Joule calorific value calculated by the Joule calorific value calculation unit, and the Joule calorific value exceeds the Joule calorific value threshold value. If so, it is evaluated that the spatter may occur.

Further, the resistance welding evaluation method includes a first step , a second step , a third step, and a fourth step . In the first step, the Joule calorific value calculation unit calculates the Joule calorific value generated in a plurality of the materials to be welded during the resistance welding based on the plate assembly conditions and the setting conditions. In the second step, the resistance ratio calculation unit determines the sum of the resistance values of the plurality of the materials to be welded and the resistance of the outer material to be welded having the thinnest plate thickness in the stacking direction among the plurality of the materials to be welded. The ratio with the value is calculated as the resistance ratio. In the third step, the upper limit value of the Joule calorific value for each of the total plate thickness and the resistance ratio in the two-dimensional plane of the total plate thickness and the resistance ratio of the plurality of the materials to be welded in the stacking direction is determined by the threshold setting unit. The Joule calorific value capable of performing the resistance welding without generating the spatter by performing the principal component analysis on the subject and using the first principal component axis obtained by the principal component analysis and the plurality of the upper limit values. The upper limit value of is set as the calorific value threshold. In the fourth step, the evaluation unit compares the calorific value threshold value set in the third step with the Joule calorific value calculated in the first step, and the Joule calorific value is the calorific value threshold value. If it exceeds, it is evaluated that the spatter may occur.

According to the present invention, if the plate assembly conditions of a plurality of materials to be welded and the setting conditions for resistance welding are set, the Joule calorific value is automatically calculated, and the calculated Joule calorific value and the calorific value threshold are set. Based on the comparison, the presence or absence of spatter is evaluated. As a result, it is possible to easily and surely evaluate the presence or absence of spatter generation in a shorter analysis time by inputting the minimum conditions.

It is a schematic block diagram of the resistance welding evaluation apparatus which concerns on this embodiment. It is explanatory drawing which divided the model of a plurality of welded materials into a mesh. It is a figure which shows the relationship between a current value and a nugget diameter. It is a figure which shows the relationship between the energization time, a nugget diameter and a contact diameter. It is a figure which shows the relationship between the energization time and the Joule calorific value. It is explanatory drawing which showed the relationship between the melt volume and the permissible Joule calorific value at the time of spatter. It is the figure which plotted the permissible Joule calorific value in the two-dimensional space of total plate thickness and resistance ratio. It is a figure for setting the spatter generation reference formula (generation amount threshold value) in the two-dimensional space of the alignment value (the first principal component axis of FIG. 7) and the permissible Joule calorific value. It is a flowchart for setting a calorific value threshold. It is a flowchart for evaluating the presence / absence of spatter.

Hereinafter, preferred embodiments of the resistance welding evaluation device and the resistance welding evaluation method according to the present invention will be described with reference to the accompanying drawings.

[1. Schematic configuration of the resistance welding evaluation device 10 according to this embodiment]
As shown in FIG. 1, the resistance welding evaluation device 10 according to the present embodiment is realized by a computer 12. The computer 12 is, for example, a control unit of the resistance welding device 14, and by executing a program stored in the memory (storage unit) 16, the input unit 18, the Joule calorific value calculation unit 20, and the resistance ratio calculation unit 22 are executed. , The functions of the threshold setting unit 24, the evaluation unit 26, the output unit 28, and the control unit 30 are realized. The resistance welding evaluation device 10 can also be realized by a general computer separate from the control unit. Further, the resistance welding device 14, for example, stacks a plurality of plate-shaped materials to be welded 32 and performs resistance welding on the laminated portions of the plurality of materials to be welded 32.

The input unit 18 receives input from the outside of the plate assembly conditions of the plurality of materials 32 to be welded and the setting conditions of resistance welding. The plate assembly conditions include the plate thickness Di (i = 1 to n, n is the number of laminated materials 32 to be welded) and the material of each of the materials 32 to be welded that constitute the plurality of materials 32 to be welded. .. Further, the setting conditions include the value (current value) I of the current flowing through the plurality of materials 32 to be welded during resistance welding, the energization time t for the plurality of materials 32 to be welded, and the like.

The Joule calorific value calculation unit 20 calculates the Joule calorific value Q generated in a plurality of materials 32 to be welded during resistance welding based on the plate assembly conditions and setting conditions input to the input unit 18. As will be described later, the Joule calorific value Q changes according to the energization time t. Therefore, the Joule calorific value calculation unit 20 can calculate the Joule calorific value Q at an arbitrary time interval by using CAE (Computer Aided Engineering).

Using the following equation (1), the resistivity ratio calculation unit 22 uses the sum of the resistance values Ωi of the plurality of materials 32 to be welded as ΣΩi, and among the plurality of materials 32 to be welded, the plate thickness Di in the stacking direction is determined. The ratio of the thinnest outer material to be welded 32 with the resistance value Ωs as the denominator is calculated as the resistance ratio Ωr. The resistivity ratio Ωr is an index indicating the deviation of the nugget 44 formed in the laminated portion of the plurality of materials 32 to be welded during resistance welding. Σ is a mathematical symbol indicating the sum of resistance values Ωi.
Ωr = ΣΩi / Ωs (1)

The threshold value setting unit 24 uses the total plate thickness Dt in the stacking direction of the plurality of materials 32 to be welded and the resistivity Ωr to perform resistance welding without generating spatter, and is the upper limit of the Joule calorific value Q. The value is set as the calorific value threshold Qth. The total plate thickness Dt means the total plate thickness Di in the stacking direction of each of the materials to be welded 32 when the plurality of materials 32 to be welded are laminated (Dt = ΣDi). Further, a specific method for setting the calorific value threshold Qth will be described later.

Further, in the present embodiment, "sputtering" is a concept including spatter generated in the early stage of energization and spatter generated in the middle or late stage of energization when a plurality of materials 32 to be welded are energized. In the following description, it should be noted that unless otherwise specified, "sputtering" is sputtering that occurs in the initial stage of energization.

The evaluation unit 26 compares the calorific value threshold Qth with the Joule calorific value Q, and evaluates whether or not the Joule calorific value Q exceeds the calorific value threshold Qth. Further, the evaluation unit 26 also determines whether or not resistance welding can be performed on the plurality of materials 32 to be welded based on the evaluation result. Specifically, if Q> Qth, the evaluation unit 26 evaluates that spatter may be generated by resistance welding, and disallows the execution of resistance welding. Further, if Q ≦ Qth, the evaluation unit 26 evaluates that there is no possibility of spattering even if resistance welding is performed, and permits the execution of resistance welding.

The output unit 28 outputs the evaluation result of the presence / absence of spatter in the evaluation unit 26 and the determination result of whether or not resistance welding can be performed to the outside.

The memory 16 includes a table 34, a library 36, and an evaluation result storage unit 38. In the table 34, the calorific value threshold Qth preset by the threshold setting unit 24 is stored. As described above, the calorific value threshold Qth is calculated based on the total plate thickness Dt and the resistivity ratio Ωr, and therefore depends on the plate assembly conditions. Therefore, the calorific value threshold Qth for each plate assembly condition is stored in the table 34.

The evaluation unit 26 reads out the corresponding calorific value threshold Qth from the table 34, and evaluates the Joule calorific value Q using the read calorific value threshold Qth. Further, the evaluation unit 26 stores the above-mentioned evaluation result and judgment result in the evaluation result storage unit 38 after the evaluation of the Joule calorific value Q. The library 36 stores a resistance value R between two electrodes 42, which will be described later.

The control unit 30 reads out the determination result stored in the evaluation result storage unit 38, and controls the resistance welding device 14 based on the read determination result.

The resistance welding device 14 includes a computer 12, a power supply 40, and two electrodes 42 that sandwich a plurality of materials 32 to be welded. When the resistance welding device 14 is controlled based on the read determination result, the control unit 30 of the computer 12 drives the power supply 40 and causes a current of an arbitrary current value I to flow between the two electrodes 42. The plurality of materials 32 to be welded are pressed from both sides in the stacking direction by the two electrodes 42. Therefore, when resistance welding is performed, a current flows through the plurality of materials 32 to be welded, so that the laminated portion is melted and the nugget 44 is formed. On the other hand, the control unit 30 does not drive the power supply 40 when the execution of resistance welding is prohibited based on the read determination result.

[2. Calorific value threshold Qth setting method]
Next, a method for setting the calorific value threshold Qth will be described with reference to FIGS. 2 to 8. Here, after explaining the problems of the conventional method of predicting the presence or absence of spatter during resistance welding in advance, the method of setting the calorific value threshold Qth in the present embodiment will be described. In this description, if necessary, the description will be made with reference to FIG.

<2.1 Conventional problems>
FIG. 2 illustrates a model for calculating a current-heat-structural coupling phenomenon that occurs during resistance welding to a plurality of materials 32 to be welded using CAE. It should be noted that the model is a model in which three sheets of the material to be welded 32 are laminated and the material to be welded 32 on both sides (outside) in the stacking direction is sandwiched between the two electrodes 42. Further, in the model, the laminated portion of the plurality of materials 32 to be welded, specifically, the space between the two electrodes 42 is finely divided by a mesh. Therefore, in the conventional method, the presence or absence of spatter is predicted by using such a model.

However, in general, the contents of CAE software are so-called black boxes, and it is unknown how to predict the occurrence of spatter. Therefore, the accuracy of predicting the occurrence of spatter may be low.

FIG. 3 is a diagram showing the relationship between the current value I of the current flowing through the laminated portion of the plurality of materials 32 to be welded during resistance welding and the diameter (nugget diameter) Dn of the nugget 44 formed in the laminated portion. is there. The nugget diameter Dn is the diameter of the nugget 44 along the direction orthogonal to the stacking direction of the plurality of materials 32 to be welded (the plane direction of the material 32 to be welded). Also, in FIG. 3, Dth is the smallest diameter of the fully grown nugget 44. Therefore, if Dn> Dth, it can be determined that the nugget 44 is sufficiently grown.

In FIG. 3, the plots marked with circles show the results (results of the actual machine) when an electric current is actually applied to the plurality of materials 32 to be welded. Moreover, the plot of the triangle mark is the prediction result using CAE. As shown in FIG. 3, the nugget diameter Dn increases as the current value I increases in both the results of the actual machine and the prediction results using CAE.

Further, in any of the results, when Dn> Dth, sputtering may occur. In FIG. 3, in the results of the actual machine, the plot when sputtering is not generated is shown by a white circle, and the plot when sputtering is occurring is shown by a black circle. On the other hand, in the CAE prediction result, the plot when sputtering is not generated is shown by a white triangle mark, and the plot when sputtering is occurring is shown by a black triangle mark.

However, as shown in FIG. 3, when the result of the actual machine and the prediction result of CAE are compared, even if the nugget diameter Dn is the same, the current value I when sputtering occurs is different. Therefore, when the occurrence of sputtering is predicted using CAE, the prediction accuracy of sputtering is lowered.

FIG. 4 is a diagram showing the relationship between the energization time t of the current to the plurality of welded materials 32 and the nugget diameter Dn and the contact diameter Dc predicted using CAE. Here, the contact diameter Dc means the diameter in the plane direction of the contact portion of the two welded materials 32 in the laminated portion of the plurality of welded materials 32 in which the nugget 44 is generated. Further, in FIG. 4, the solid line is the prediction result showing the change in the nugget diameter Dn with respect to the energization time t (growth of the nugget 44), and the broken line is the prediction result showing the change in the contact diameter Dc with respect to the energization time t.

In this case, if the period in which the nugget diameter Dn exceeds the contact diameter Dc continues for a certain period of time, it is possible to predict that sputtering has occurred. That is, if the nugget diameter Dn of the nugget 44, which is the molten portion, is larger than the contact diameter Dc, it can be considered that sputtering has occurred.

Here, although not shown, in the results of the actual machine, the nugget diameter Dn and the contact diameter Dc gradually increase as the temperature of the plurality of materials 32 to be welded rises due to energization. On the other hand, in the CAE prediction result of FIG. 4, the contact diameter Dc increases stepwise as the energization time t elapses. In CAE, as shown in FIG. 2, a plurality of materials to be welded 32 are divided into a rectangular (square in cross section) mesh, and two materials to be welded at the vertices (nodes) of the elements of the square mesh. This is because it is determined whether or not the 32 contacts are present.

In particular, when the material 32 to be welded is a metal material having a plating layer, the accuracy of determining the presence or absence of contact is lowered due to the presence of the plating layer as compared with the contact between so-called bare materials. As a result, the discrepancy between the result of the actual machine and the predicted result of CAE, including the result of the contact diameter Dc, becomes even larger.

<2.2 Method for setting calorific value threshold Qth in this embodiment>
Therefore, in the present embodiment, the Joule calorific value Q generated in the plurality of materials 32 to be welded due to the current flowing between the two electrodes 42 during resistance welding is used instead of the prediction using the mesh. , Predict (evaluate) the presence or absence of spatter. In order to perform such an evaluation, in the present embodiment, prior to the evaluation of the presence or absence of spatter, the upper limit of the Joule calorific value Q that enables resistance welding without spattering is set as the calorific value threshold Qth. Set in advance. This setting work is executed by the Joule calorific value calculation unit 20 and the threshold value setting unit 24.

Specifically, as shown in FIG. 1, during resistance welding, a current of an arbitrary current value I is applied to a plurality of materials 32 to be welded from a power source 40 via two electrodes 42 for an arbitrary energization time t. When flowing, if the resistance value between the two electrodes 42 is R, the Joule calorific value Q generated in the plurality of welded materials 32 due to the current value I can be expressed by the following equation (2). it can.
Q = I ² x R x t (2)

The resistance value R depends on the plate assembly conditions such as the plate thickness Di and the material of each material 32 to be welded that constitutes the plurality of materials 32 to be welded. Therefore, for example, the resistance value R for each arbitrary time interval may be obtained in advance by using the above-mentioned CAE for each plate assembly condition and stored in the library 36. As a result, the Joule calorific value calculation unit 20 reads out the corresponding resistance value R stored in the library 36, and uses the read resistance value R from the simple calculation formula of the above equation (2) at an arbitrary time interval. The Joule calorific value Q for each can be easily calculated.

FIG. 5 shows the relationship between the Joule calorific value Q and the energization time t. The Joule calorific value Q increases as the energization time t increases. Further, when compared at the same energization time t, the Joule calorific value Q increases as the current value I increases, while it decreases as the current value I decreases.

Then, when the Joule calorific value Q exceeds a predetermined calorific value, that is, an upper limit value of the Joule calorific value Q (hereinafter, also referred to as an allowable Joule calorific value Qp) capable of performing resistance welding without generating sputtering. , Spatter is expected to occur. In this case, the permissible Joule calorific value Qp becomes a value different depending on the plate assembly conditions such as the total plate thickness Dt and the resistance value R (resistance ratio Ωr).

FIG. 6 is an explanatory diagram conceptually illustrating the relationship between the allowable Joule calorific value Qp and the plate assembly conditions. Here, for example, a case where three sheets of materials 32 to be welded such as high-strength steel are laminated and a nugget 44 is formed by resistance welding will be described.

In this case, if the total plate thickness Dt of the plurality of materials 32 to be welded is increased, the volume of the molten portion (the volume of the nugget 44, which is also referred to as the molten volume) when sputtering occurs increases, and the allowable joules are increased. It is expected that the calorific value Qp will increase. Further, if the resistivity ratio Ωr of the plurality of materials 32 to be welded increases by changing the material of the material 32 to be welded, the current value I when spatter occurs decreases and the molten volume when spatter occurs becomes small. At the same time, it is expected that the allowable Joule calorific value Qp becomes smaller. In fact, in the verification experiment on the actual machine, the results supporting the above prediction were obtained.

As described above, regarding the generation of sputtering, the molten volume depends on the plate assembly conditions such as the plate thickness Di and the material of each material 32 to be welded constituting the plurality of materials 32 to be welded. Further, the melt volume has a correlation with the allowable Joule calorific value Qp (Joule calorific value Q). Based on these findings, the calorific value threshold Qth as the allowable Joule calorific value Qp under arbitrary plate assembly conditions was determined by the methods shown in FIGS. 7 and 8.

In FIG. 7, for a plurality of materials 32 to be welded, the allowable Joule calorific value Qp when the combination of the plate thickness Di of each material 32 to be welded is changed, the total plate thickness Dt is the horizontal axis, and the resistivity Ωr is the horizontal axis. This is the result of plotting in the two-dimensional space. The combination of the plate thickness Di means, for example, that all three sheets of the material to be welded 32 are relatively thin plates, or one of the three sheets of the material to be welded 32 is a relatively thick plate. Yes, it refers to a combination such as when the other two sheets are thin plates.

In FIG. 7, the permissible Joule calorific value Qp appears to be plotted randomly. Therefore, the principal component analysis is performed on the two-dimensional plane of FIG. 7, and the first principal component axis 46 of the thick arrow line extending diagonally downward is set. Next, the plotted information on the allowable Joule calorific value Qp is aggregated on the first principal component axis 46 in the direction orthogonal to the first principal component axis 46, as shown by a thin arrow line. As a result, two parameters of the resistance ratio Ωr and the total plate thickness Dt are combined with respect to the allowable Joule calorific value Qp.

FIG. 8 shows information on the allowable Joule calorific value Qp aggregated on the first principal component axis 46 in a two-dimensional space having the first principal component axis 46 of FIG. 7 as the horizontal axis and the allowable Joule calorific value Qp as the vertical axis. It is a plot.

In FIG. 8, the white circles are the upper limit values of the allowable Joule calorific value Qp under arbitrary plate assembly conditions calculated by the Joule calorific value calculation unit 20. The white triangular mark is the lower limit of the allowable Joule calorific value Qp under arbitrary plate assembly conditions calculated by the Joule calorific value calculation unit 20. Further, the black circle mark is an allowable Joule calorific value Qp obtained when an electric current is actually passed through a plurality of materials 32 to be welded under arbitrary plate assembly conditions. The above-mentioned upper limit value and lower limit value refer to the upper limit value and the lower limit value of the allowable Joule calorific value Qp according to the calculation accuracy of the resistance value R by CAE.

As is clear from FIG. 8, the permissible Joule calorific value Qp calculated in the resistance welding evaluation device 10 and the permissible Joule calorific value Qp obtained from the result of the actual machine are approximately the same in the two-dimensional space of FIG. It is plotted in the same area.

Further, as described above, if the total plate thickness Dt is large, the permissible Joule calorific value Qp is large, and if the resistance ratio Ωr is large, the permissible Joule calorific value Qp is small. Therefore, as shown in FIG. 7, when the information on the allowable Joule calorific value Qp is aggregated on the first principal component axis 46, among the thick arrow lines, on the root side of the arrow having a large resistivity Ωr and a small total plate thickness Dt. The permissible Joule calorific value Qp becomes smaller, while the permissible Joule calorific value Qp becomes larger on the arrow direction side of the arrow where the resistivity Ωr is small and the total plate thickness Dt is large. In FIG. 8, as the value of the first principal component axis 46 (hereinafter, also referred to as an alignment value) increases so as to reflect the concept of FIG. 6, the permissible Joule calorific value Qp increases. ..

Therefore, in the two-dimensional space of FIG. 8, a curve passing through the center of the plotted data group of allowable Joule calorific value Qp was obtained. This curve is a threshold line indicating a representative value (median value) of the allowable Joule calorific value Qp with respect to the alignment value, which is obtained by a statistical method. The threshold value setting unit 24 determines (sets) this curve as the calorific value threshold value Qth (sputter generation reference formula). That is, as described above, there is no data discrepancy between the permissible Joule calorific value Qp obtained by calculation and the permissible Joule calorific value Qp obtained by the result of the actual machine. Therefore, it is considered that the curve passing through the center of these data groups may be set in the sputter generation reference formula. Actually, since the allowable Joule calorific value Qp differs for each plate assembly condition, the threshold value setting unit 24 sets the calorific value threshold Qth for each plate assembly condition and stores the set calorific value threshold Qth in the table 34. To do.

[3. Operation of resistance welding evaluation device 10 according to this embodiment (resistance welding evaluation method)]
Next, the operation of the resistance welding evaluation device 10 according to the present embodiment will be described with reference to FIGS. 9 and 10. In this operation description, if necessary, it will be described with reference to FIGS. 1 to 8.

<3.1 Setting of calorific value threshold Qth>
First, the operation of setting the calorific value threshold Qth will be described with reference to the flowchart of FIG.

In step S1, the plate assembly conditions of the plurality of materials 32 to be welded and the setting conditions for resistance welding are input to the input unit 18 from the outside. For example, the plate thickness Di and material of each material 32 to be welded constituting the plurality of materials 32 to be welded, the current value I and the energization time t at the time of resistance welding are input.

In step S2, the Joule calorific value calculation unit 20 calculates the allowable Joule calorific value Qp using the above equation (2) based on the plate assembly conditions and setting conditions input to the input unit 18.

In step S3, the resistivity calculation unit 22 calculates the resistivity Ωr using the above equation (1) based on the plate assembly conditions input to the input unit 18.

In step S4, the threshold setting unit 24 plots the allowable Joule calorific value Qp in the two-dimensional space of the total plate thickness Dt and the resistance ratio Ωr as shown in FIG. After that, the threshold value setting unit 24 performs principal component analysis on the two-dimensional space, and collects information on the allowable Joule calorific value Qp on the first principal component axis 46.

In step S5, the threshold setting unit 24 plots the permissible Joule calorific value Qp in the two-dimensional space of the first principal component axis 46 (aligned value) and the permissible Joule calorific value Qp, as shown in FIG. Next, the threshold value setting unit 24 creates a curve passing through the center of the data group of the allowable Joule calorific value Qp in the two-dimensional space, and determines the curve as a spatter generation reference formula (calorific value threshold Qth).

In step S6, the threshold value setting unit 24 stores the determined sputtering generation reference formula (calorific value threshold value Qth) in the table 34.

In step S7, the threshold value setting unit 24 determines whether or not to end the setting work of the calorific value threshold value Qth. If it is desired to set the spatter generation reference formula for other plate assembly conditions (step S7: NO), the process returns to step S1 or S2, and the calorific value threshold Qth setting work for the other plate assembly conditions is executed. On the other hand, if the spatter generation reference formulas for all the plate assembly conditions are set (step S7: YES), the calorific value threshold Qth setting work is completed.

<3.2 Evaluation of the presence or absence of spatter>
Next, the evaluation work of the presence or absence of spatter generation will be described with reference to the flowchart of FIG.

In step S11, the input unit 18 receives from the outside the plate assembly conditions of the plurality of materials 32 to be welded and the setting conditions for resistance welding, as in step S1 of FIG.

In step S12 (first step), the joule calorific value calculation unit 20 uses the above equation (2) based on the plate assembly conditions and setting conditions input to the input unit 18 as in step S2. The calorific value Q is calculated.

In step S13, the evaluation unit 26 reads out from the table 34 the calorific value threshold Qth corresponding to the plate assembly condition used for calculating the Joule calorific value Q.

In step S14 (second step), the evaluation unit 26 compares the read calorific value threshold value Qth with the Joule calorific value Q. Specifically, the evaluation unit 26 determines whether or not the Joule calorific value Q exceeds the calorific value threshold Qth.

If Q> Qth (step S14: YES), the process proceeds to step S15 (second step). In step S15, the evaluation unit 26 evaluates that the Joule calorific value Q exceeds the calorific value threshold Qth, so that spatter may occur. In the next step S16, the evaluation unit 26 determines that the execution of resistance welding is not permitted based on the evaluation result.

On the other hand, when Q ≦ Qth (step S14: NO), the process proceeds to step S17. In step S17, the evaluation unit 26 evaluates that there is no possibility of spattering because the Joule calorific value Q is equal to or less than the calorific value threshold Qth. In the next step S18, the evaluation unit 26 determines that the execution of resistance welding is permitted based on the evaluation result.

In step S19 after step S16 or S18, the evaluation unit 26 stores the evaluation result in step S15 or S17 and the determination result in step S16 or S18 in the evaluation result storage unit 38. Alternatively, the evaluation unit 26 outputs the evaluation result and the determination result to the outside via the output unit 28.

Next, the evaluation unit 26 determines whether or not to continuously evaluate the presence or absence of spatter. If it is continued (step S20: NO), the process returns to step S11 or S12, and the evaluation of the presence or absence of spatter generation is continued. On the other hand, when the evaluation of the presence / absence of spatter is not continuously performed (step S20: YES), the evaluation work of the presence / absence of spatter is completed.

[4. Effect of this embodiment]
As described above, in the resistance welding evaluation device 10 and the resistance welding evaluation method according to the present embodiment, when resistance welding is performed on the laminated portions of the plurality of materials 32 to be welded, the plates of the plurality of materials 32 to be welded Whether or not spatter occurs is evaluated based on the assembly conditions and the setting conditions for resistance welding.

That is, the resistance welding evaluation device 10 has a Joule calorific value calculation unit 20 and an evaluation unit 26. The Joule calorific value calculation unit 20 calculates the Joule calorific value Q generated in a plurality of materials 32 to be welded during resistance welding based on the plate assembly conditions and the setting conditions. The evaluation unit 26 uses the resistivity Ωr based on the resistance values Ωi of the plurality of materials 32 to be welded and the total plate thickness Dt in the stacking direction of the plurality of materials 32 to be welded to obtain a calorific value threshold Qth (sputter generation reference formula). ) And the Joule calorific value Q, and if the Joule calorific value Q exceeds the calorific value threshold Qth, it is evaluated that spatter may occur.

Further, the resistance welding evaluation method includes a first step (step S12) and a second step (steps S14, S15). In the first step, the Joule calorific value calculation unit 20 calculates the Joule calorific value Q generated in a plurality of materials 32 to be welded during resistance welding based on the plate assembly conditions and the setting conditions. In the second step, the calorific value threshold Qth obtained by the evaluation unit 26 using the resistivity Ωr based on the resistance values Ωi of the plurality of materials 32 to be welded and the total plate thickness Dt in the stacking direction of the plurality of materials 32 to be welded. And the Joule calorific value Q are compared, and if the Joule calorific value Q exceeds the calorific value threshold Qth, it is evaluated that spatter may occur.

In this way, if the plate assembly conditions of the plurality of materials 32 to be welded and the setting conditions for resistance welding are set, the Joule calorific value Q is automatically calculated, and the calculated Joule calorific value Q and the calorific value threshold Qth are calculated. Based on the comparison with, the presence or absence of spatter generation is evaluated. As a result, the presence or absence of spatter generation can be easily and reliably evaluated in a shorter analysis time by inputting the minimum conditions without being affected by the mesh characteristics of the conventional finite element analysis. Is possible. In particular, in the present embodiment, it is possible to predict with higher accuracy the presence or absence of spatter at the initial stage of energization in the high-strength steel plate assembly.

The above effects will be described more specifically. For example, when designing a new model vehicle, in the process of deciding the steel plate (plate assembly) to be used for the vehicle body, resistance welding is performed using the resistance welding equipment already installed in the vehicle manufacturing plant and the current settings. It is necessary to determine whether or not a problem such as spattering occurs when executing the above. In the present embodiment, resistance welding is performed without generating spatter by comparing the calorific value threshold Qth based on the total plate thickness Dt and the resistivity ratio Ωr of the plate set to be resistance welded with the Joule calorific value Q. It is possible to easily confirm whether or not it can be executed.

Moreover, in the present embodiment, the Joule calorific value Q for each arbitrary time interval can be calculated from the resistance value R obtained by using CAE from the simple calculation formula of the above formula (2). As a result, the presence or absence of spatter can be evaluated with higher accuracy.

Here, the resistance welding evaluation device 10 uses the sum of the resistance values Ωi of the plurality of materials 32 to be welded ΣΩi and the outer material 32 to be welded having the thinnest plate thickness Di in the stacking direction among the plurality of materials 32 to be welded. Joule calorific value Q that enables resistance welding without generating spatter by using the resistance ratio calculation unit 22 that calculates the ratio to the resistance value Ωs as the resistance ratio Ωr, the total plate thickness Dt, and the resistance ratio Ωr. Further includes a threshold setting unit 24 for setting the upper limit value of the calorific value as the calorific value threshold Qth. Thereby, the resistivity ratio Ωr and the calorific value threshold value Qth can be calculated easily and quickly.

Further, the threshold value setting unit 24 relates to an upper limit value (allowable Joule calorific value Qp) of the Joule calorific value Q for each total plate thickness Dt and the resistance ratio Ωr in the two-dimensional plane of the total plate thickness Dt and the resistance ratio Ωr in FIG. Principal component analysis is performed, and the calorific value threshold Qth is set using the first principal component axis 46 obtained by the principal component analysis and a plurality of upper limit values. As a result, the calorific value threshold Qth can be set with high accuracy, and the evaluation accuracy of the presence or absence of spatter can be improved.

Further, the resistance welding evaluation device 10 further has a memory (storage unit) 16 for storing the calorific value threshold value Qth for each plate assembly condition. The evaluation unit 26 reads the calorific value threshold Qth according to the plate assembly condition of the Joule calorific value Q calculated by the Joule calorific value calculation unit 20 from the memory 16, and compares the read calorific value threshold Qth with the Joule calorific value Q. Then, the presence or absence of the possibility of spattering is evaluated. This makes it possible to accurately and quickly evaluate the presence or absence of spatter.

It should be noted that the present invention is not limited to the above-described embodiment, and it goes without saying that various configurations can be adopted based on the contents described in this specification.

10 ... Resistance welding evaluation device 16 ... Memory (memory unit)
20 ... Joule calorific value calculation unit 22 ... Resistor ratio calculation unit 24 ... Threshold setting unit 26 ... Evaluation unit 32 ... Welded material 46 ... First principal component axis

Claims (3)

When resistance welding is performed on a laminated portion of a plurality of materials to be welded, it is evaluated whether or not spatter occurs based on the plate assembly conditions of the plurality of materials to be welded and the setting conditions of the resistance welding. In the resistance welding evaluation device for
A Joule calorific value calculation unit that calculates the Joule calorific value generated in a plurality of the materials to be welded during the resistance welding based on the plate assembly conditions and the set conditions.
The resistivity ratio calculated as the resistance ratio is the ratio of the sum of the resistance values of the plurality of materials to be welded to the resistance values of the outer materials to be welded having the thinnest plate thickness in the stacking direction among the plurality of materials to be welded. Calculation unit and
Principal component analysis is performed on the upper limit of the Joule calorific value for each of the total plate thickness and the resistance ratio in the two-dimensional plane of the total plate thickness and the resistance ratio of the plurality of the materials to be welded in the stacking direction. Using the first principal component axis obtained by the analysis and the plurality of the upper limit values, the upper limit value of the Joule calorific value capable of performing the resistance welding without generating the spatter is set as the calorific value threshold value. Threshold setting unit and
The calorific value threshold set by the threshold value setting unit is compared with the Joule calorific value calculated by the Joule calorific value calculation unit, and if the Joule calorific value exceeds the Joule calorific value threshold value, the sputtering is performed. Evaluation department that evaluates that there is a possibility that
Has a resistance welding evaluation device. In the resistance welding evaluation apparatus according to claim 1 ,
Further having a storage unit for storing the calorific value threshold value for each plate assembly condition,
The evaluation unit reads out the calorific value threshold value of the Joule calorific value calculated by the Joule calorific value calculation unit according to the plate assembly condition from the storage unit, and reads out the calorific value threshold value and the Joule calorific value. A resistance welding evaluation device that evaluates the possibility of spattering by comparing the above. When resistance welding is performed on a laminated portion of a plurality of materials to be welded, it is evaluated whether or not spatter occurs based on the plate assembly conditions of the plurality of materials to be welded and the setting conditions of the resistance welding. In the resistance welding evaluation method for
The first step of calculating the Joule calorific value generated in a plurality of the materials to be welded during the resistance welding by the Joule calorific value calculation unit based on the plate assembly condition and the setting condition.
The resistance ratio calculation unit resists the ratio of the total resistance value of the plurality of materials to be welded to the resistance value of the outer material to be welded, which has the thinnest plate thickness in the stacking direction among the plurality of materials to be welded. The second step to calculate as a ratio and
The threshold setting unit performs principal component analysis on the upper limit of the Joule calorific value for each of the total plate thickness and the resistance ratio in the two-dimensional plane of the total plate thickness and the resistance ratio of the plurality of the materials to be welded in the stacking direction. Then, using the first principal component axis obtained by the principal component analysis and the plurality of the upper limit values, the upper limit value of the Joule calorific value capable of performing the resistance welding without generating the spatter is set. The third step to set as the calorific value threshold and
The evaluation unit compares the calorific value threshold set in the third step with the Joule calorific value calculated in the first step, and if the Joule calorific value exceeds the calorific value threshold value, The fourth step of evaluating that spatter may occur, and
A resistance welding evaluation method having.

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