JP5878779B2 - Laser welding state determination method and laser welding state determination device - Google Patents

Description

  The present invention relates to a laser welding state determination method and a laser welding state for determining a welding state when a resin member that is transparent to laser light and a resin member that is absorbent to laser light are joined by laser welding. The present invention relates to a determination device.

  A method of joining resin members by laser welding is known. This method is a resin member that is transmissive to laser light (hereinafter referred to as “transparent resin member”) and a resin member that is absorbent to laser light (hereinafter referred to as “absorbent resin member”). ) And irradiating laser light from the transparent resin member side generates heat and melts the irradiated portion of the absorbent resin member, and the transparent resin member also generates heat due to heat transfer from the absorbent resin member. A method of melting and welding the permeable resin member and the absorbent resin member thereby.

  During laser welding, if there is a gap between the permeable resin member and the absorbent resin member due to, for example, deformation of the member, sufficient heat is generated from the absorbent resin member generated by the laser light to the permeable resin member. Since the transmission resin member does not transmit, the permeable resin member does not sufficiently generate heat and melt, and a defective weld state such as a decrease in welding strength or a gap at the welding position may occur. As a method for determining the welding state, a method is known in which the temperature at the welding position is detected using a sensor during laser welding, and if the detected temperature exceeds a predetermined threshold, the welding state is determined to be defective. (For example, refer to Patent Document 1). In this determination method, when there is a gap between the permeable resin member and the absorbent resin member at the time of laser welding, the amount of heat transfer from the absorbent resin member to the permeable resin member compared to the case where there is no gap. Is based on the knowledge that the temperature of the absorbent resin member becomes higher as a result.

JP 2006-341563 A JP 2004-17120 A

  The temperature at the welding position during laser welding may vary due to changes over time in the output of the laser irradiation device, quality variations of the resin member to be welded, changes in environmental temperature, and the like. Therefore, in the method for determining the welding state using the fixed threshold as described above, it is determined that a good one is actually defective or is actually a bad one under the influence of such temperature fluctuation factors. In some cases, it is determined to be good, and there is room for improvement in terms of determination accuracy.

SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.
1st form of this invention is a laser welding state determination which determines the welding state at the time of joining the resin member transparent to a laser beam, and the resin member which absorbs a laser beam by laser welding Is the method. This laser welding state determination method includes a step of detecting a temperature or a calorific value generated by exothermic melting at a welding position during laser welding using a sensor, and the temperature or calorific value in a predetermined effective period within a laser welding period. Determining whether the calculated value is within a predetermined range for at least one of the step of calculating at least one of the amount of change and the slope of change, and at least one of the amount of change in temperature or heat generation and the slope of change A process.
In the case where a gap exists between the resin members to be welded in a part of the welding locus, the temperature at the welding position rises greatly in a portion corresponding to the gap and changes rapidly. Due to the presence of a gap to determine whether the calculated value is within a predetermined range for at least one of the change in temperature or the amount of heat generated during the predetermined effective period of the laser welding period and the slope of the change. It is possible to determine whether or not there is a poor welded state. Here, even if the temperature of the welding position during laser welding fluctuates due to changes in the output of the laser irradiation device over time, variations in the quality of the resin member to be welded, changes in the environmental temperature, etc. Since it is considered that the welding period is the same in a predetermined effective period, such temperature fluctuation hardly affects the change amount or the inclination of the temperature or the heat generation amount. Therefore, in this determination method, even if the temperature at the welding position during laser welding may fluctuate due to the above-described factors, the welding state can be accurately determined.

[Application Example 1] In a laser welding state determination method for determining a welding state when a resin member that is transparent to laser light and a resin member that is absorbent to laser light are joined by laser welding,
A step of detecting an index value correlated with the temperature at the welding position using a sensor during laser welding;
Calculating at least one of a change amount and a change slope of the index value in a predetermined effective period of the laser welding period; and
Determining whether the calculated value is within a predetermined range for at least one of the change amount of the index value and the slope of the change.

  In the case where a gap exists between the resin members to be welded in a part of the welding locus, the temperature at the welding position rises greatly in a portion corresponding to the gap and changes rapidly. Due to the presence of a gap to determine whether the calculated value is within a predetermined range for at least one of the amount of change in the temperature correlation index value and the slope of the change during the predetermined effective period within the laser welding period. It is possible to determine whether or not there is a poor welded state. Here, even if the temperature of the welding position during laser welding fluctuates due to changes in the output of the laser irradiation device over time, variations in the quality of the resin member to be welded, changes in the environmental temperature, etc. Since it is considered that the welding period is almost the same during a predetermined effective period, such temperature fluctuation hardly affects the change amount or inclination of the temperature correlation index value. Therefore, in this determination method, even if the temperature at the welding position during laser welding may fluctuate due to the above-described factors, the welding state can be accurately determined.

[Application Example 2] The laser welding state determination method according to Application Example 1,
The laser welding state determination method, wherein the change amount is a difference between a maximum value of the index value in the effective period and a reference value derived from the index value.

  If there is a gap, there is a high possibility that the temperature correlation index value will take the maximum value in the part corresponding to the gap, so this method will accurately determine the welding state based on the amount of change in the temperature correlation index value. can do.

[Application Example 3] The laser welding state determination method according to Application Example 2,
The laser welding state determination method, wherein the reference value is a minimum value of the index value in the effective period.

  In this method, the amount of change in the temperature correlation index value during the effective period within the laser welding period can be properly grasped, and the welding state can be determined with high accuracy.

[Application Example 4] The laser welding state determination method according to Application Example 2,
The laser welding state determination method, wherein the reference value is an average value of the index values in the effective period.

  With this method, even if an abnormal value with an extremely small temperature correlation index value is detected, the amount of change in the temperature correlation index value during the effective period within the laser welding period can be properly grasped, and welding can be performed with high accuracy. The state can be determined.

[Application Example 5] The laser welding state determination method according to any one of Application Examples 1 to 4,
The laser welding state determination method, wherein the effective period is a period obtained by removing at least one of a first predetermined period and a last predetermined period from the laser welding period.

  In this method, except for the transition period until the laser output reaches the rated value, the transition period until the laser output is cut off, and the period during which the temperature correlation index value is considered to be unstable, such as the overlap part of the welding trajectory. Since the determination is performed, the determination accuracy can be further improved.

[Application Example 6] The laser welding state determination method according to any one of Application Examples 1 to 5, further comprising:
A laser welding state determination method comprising a step of performing at least one of an abnormal data masking process and a noise removal process on the detected index value before the calculating step.

  In this method, the influence of abnormal data and noise in the detected temperature correlation index value can be excluded, and the determination accuracy can be further improved.

  In addition, this invention can be implement | achieved in various aspects, for example, can be implement | achieved with forms, such as a determination method of a laser welding state, a laser welding state determination apparatus, a laser welding state determination system.

It is explanatory drawing which shows the structure of the laser welding system 10 in 1st Example of this invention. It is explanatory drawing which shows the outline | summary of laser welding. It is a flowchart which shows the flow of the welding state determination process in a present Example. It is explanatory drawing which shows an example of the temperature curve CT which temperature data represents. It is explanatory drawing which shows the determination method of the welding state in a comparative example. It is a flowchart which shows the flow of the welding state determination process in 2nd Example.

Next, embodiments of the present invention will be described in the following order based on examples.
A. First embodiment:
A-1. Configuration of laser welding system:
A-2. Welding state judgment processing:
B. Second embodiment:
C. Variations:

A. First embodiment:
A-1. Configuration of laser welding system:
FIG. 1 is an explanatory view showing a configuration of a laser welding system 10 in the first embodiment of the present invention. The laser welding system 10 is a system that joins resin members together by laser welding and determines a welding state.

  The laser welding system 10 includes a laser irradiation device 12 for performing laser welding. FIG. 2 is an explanatory view showing an outline of laser welding. At the time of laser welding, a transparent resin member 22 that is transmissive to the laser beam LA and an absorbent resin member 24 that is permeable to the laser beam LA are overlapped and stacked by a pressing jig (not shown). Pressurized along the direction. In this state, the laser irradiation device 12 (FIG. 1) is moved relative to each of the resin members 22 and 24 along a planned welding track (not shown) that follows a track substantially the same as the welding track WL. Laser light LA is irradiated from the resin member 22 side. Thereby, the absorbent resin member 24 is irradiated with the laser light LA transmitted through the transparent resin member 22, and the portion irradiated with the laser light LA in the absorbent resin member 24, that is, the transparent resin in the absorbent resin member 24. The boundary portion with the member 22 generates heat and melts. Further, due to heat transfer from the absorbent resin member 24, the boundary portion between the permeable resin member 22 and the absorbent resin member 24 also generates heat and melts. A welded portion 26 (FIG. 1) is formed around the boundary portion between the absorbent resin member 24 and the permeable resin member 22 by the melted portion of the permeable resin member 22 and the absorbent resin member 24, and thereby both are joined. The In the example shown in FIG. 2, the welding locus WL is substantially rectangular, and the first and last part of the welding locus WL overlap. In the example shown in FIG. 2, a gap GA exists between the permeable resin member 22 and the absorbent resin member 24 in a part of the welding locus WL.

  As the absorptive resin member 24, a resin that has thermoplasticity and can absorb without transmitting the laser beam LA can be used. For example, as the absorbent resin member 24, polyamide (PA), polyethylene (PE), polypropylene (PP), polycarbonate (PC), polyoxymethylene (POM), acrylonitrile-butadiene-styrene (ABS), polybutylene terephthalate (PBT) ), Polyphenylene sulfide (PPS), acrylic (PMME) or the like, and a mixture of a predetermined colorant such as carbon black, dye, or pigment can be used. Moreover, as the transparent resin member 22, a resin having thermoplasticity and a predetermined transmittance with respect to the laser light LA can be used. For example, the resin material exemplified above can be used as the permeable resin member 22. In this case, a colorant may be mixed in the resin material as long as a predetermined transmittance for the laser beam LA can be secured. In addition, reinforcing fibers such as glass fibers and carbon fibers may be added to the permeable resin member 22 and the absorbent resin member 24. Further, the combination of the permeable resin member 22 and the absorbent resin member 24 is preferably a combination of compatible materials.

  The laser beam LA is of a type having a wavelength such that the transmittance of the transparent resin member 22 is equal to or greater than a predetermined value due to the absorption spectrum, plate thickness (transmission length), etc. of the transparent resin member 22. The laser beam LA is appropriately selected. For example, a YAG laser, a semiconductor laser, a glass-neodymium laser, a ruby laser, a helium-neon laser, a krypton laser, an argon laser, a hydrogen laser, or a nitrogen laser can be used.

  The laser welding system 10 (FIG. 1) includes an infrared sensor 14, a sensor amplifier 16, and a determination device 18. The infrared sensor 14 moves relative to the resin members 22 and 24 together with the laser irradiation device 12, and detects the temperature of the welding position during laser welding. The temperature at the welding position during laser welding is the welding position between the permeable resin member 22 and the absorbent resin member 24 after a predetermined time has elapsed from the moment the laser beam LA is input to the absorbent resin member 24 ( It means the temperature at the position where each other faces. The predetermined time is determined by the positional relationship between the laser irradiation device 12 and the infrared sensor 14 and the moving speed of the laser irradiation device 12 and the infrared sensor 14. This predetermined time is preferably a short time. A signal representing the temperature detected by the infrared sensor 14 is amplified by the sensor amplifier 16 and input to the determination device 18. The determination device 18 is configured using a computer including a CPU and a memory, and performs welding state determination processing described below using the input temperature data. The infrared sensor 14 and the sensor amplifier 16 correspond to a detection unit in the present invention, and the determination device 18 corresponds to a calculation unit and a determination unit in the present invention.

A-2. Welding state judgment processing:
FIG. 3 is a flowchart showing the flow of the welding state determination process in the present embodiment. The welding state determination process is a process for determining the quality of the welding state between the laser-welded transparent resin member 22 and the absorbent resin member 24, and more specifically, as in the example shown in FIG. This is a process for detecting a defective weld state caused by the presence of the gap GA between the permeable resin member 22 and the absorbent resin member 24 in a part of the welding locus WL. If there is a gap GA between the permeable resin member 22 and the absorbent resin member 24 at the time of laser welding, heat is not sufficiently transmitted from the absorbent resin member 24 generated by the laser beam LA to the transmissive resin member 22. For this reason, the permeable resin member 22 does not sufficiently generate heat and melt, and a defective weld state such as a decrease in welding strength or a gap at the welding position may occur. Such defects in the welded state are caused by foreign matter (water or gas) entering through the defective part in the product after welding, which adversely affects the operation of internal installations (for example, electronic circuits) or corrodes metal parts. And the welded member may fall off, which is not preferable. The welding state determination process is executed to determine whether or not there is a defect in such a welding state.

  First, the determination device 18 reads temperature data representing the temperature at the welding position detected during laser welding from the infrared sensor 14 and the sensor amplifier 16 (step S110). FIG. 4 is an explanatory diagram illustrating an example of a temperature curve CT represented by temperature data. As shown in FIG. 4, in this embodiment, the temperature T at the welding position is continuously detected (measured) by the infrared sensor 14 from the laser welding start time t0 to the end time te.

  In FIG. 4, an example of a temperature curve CT in the case where a gap GA exists between the permeable resin member 22 and the absorbent resin member 24 in a part of the welding locus WL as in the example shown in FIG. Is shown by a solid line. In this temperature curve CT, the temperature T is prominently higher than the other periods in the middle of the laser welding period, but this temperature rise is caused by the presence of the gap GA. FIG. 4 also shows an example of the temperature curve CTx when there is no gap GA by a two-dot chain line (however, a portion common to the temperature curve CT is not shown). In this temperature curve CTx, there is no period in which the temperature T is prominently higher than other periods.

  The determination device 18 discards the data in the temperature unstable period among the temperature data (step S120). Specifically, the determination device 18 determines the data of the first predetermined period (period from t0 to t1 in FIG. 4) and the last of the temperature data of the laser welding period (period from t0 to te in FIG. 4). The data of a predetermined period (period from t2 to te in FIG. 4) are discarded. This first predetermined period corresponds to a transition period until the laser output from the laser irradiation device 12 reaches the rated value, and the laser output is cut off due to the overlap of the welding locus WL or the end of laser irradiation in the last predetermined period. This corresponds to the transition period until the temperature T, and as illustrated in FIG. In this embodiment, in order to further improve the determination accuracy, data in these periods is discarded. In the present embodiment, a period (a period from t1 to t2 in FIG. 4) excluding the first predetermined period and the last predetermined period in the laser welding period is also referred to as an effective period.

  Next, in order to further improve the determination accuracy, the determination device 18 performs abnormal data masking processing and noise removal processing using a low-pass filter on the temperature data (steps S130 and S140). These processes can be executed in any order. In addition, since these processes can be performed by a well-known method, detailed description is abbreviate | omitted here.

  Next, the determination device 18 extracts the maximum value T (max) and the minimum value T (min) of the detected temperature in the effective period (period from t1 to t2 in FIG. 4) of the laser welding period (step) S154). Next, the determination device 18 determines whether or not the difference ΔT (= T (max) −T (min)) between the maximum value T (max) and the minimum value T (min) is equal to or less than a predetermined threshold value ΔT0. (Step S164). The difference ΔT is the amount of change in the detected temperature during the effective period within the laser welding period. The determination device 18 determines that the welding state is good when the difference ΔT is equal to or smaller than the threshold value ΔT0 (step S170), and determines that the welding state is bad when the difference ΔT is larger than the threshold value ΔT0. (Step S180).

  As illustrated by a solid line in FIG. 4, when a gap GA exists between the permeable resin member 22 and the absorbent resin member 24 in a part of the welding locus WL, the temperature curve CT is in the gap GA. It rises greatly in the corresponding part. Therefore, when the gap GA exists, the difference ΔT between the maximum value T (max) and the minimum value T (min) of the detected temperature is relatively large. On the other hand, as exemplified by a two-dot chain line in FIG. 4, when such a gap GA does not exist, the temperature curve CTx does not partially rise extremely. Therefore, the difference ΔT is relatively small when there is no gap GA. Therefore, it is determined whether or not the difference ΔT between the maximum value T (max) and the minimum value T (min) of the detected temperature is equal to or less than the threshold value ΔT0, so that there is a defective weld state due to the presence of the gap GA. It can be determined whether or not.

  FIG. 5 is an explanatory diagram illustrating a method for determining a welding state in a comparative example. The determination method of the welding state in the comparative example is a method of determining whether the welding state is good or not by determining whether or not the entire temperature curve CT is equal to or less than a predetermined threshold Tth. Here, the temperature at the welding position during laser welding may vary due to changes in the output of the laser irradiation device 12 with time, quality variations of the resin members 22 and 24, changes in environmental temperature, and the like. Therefore, the temperature detection result of the welding position may be, for example, a temperature curve CT (1) in FIG. 5 or a temperature curve CT (2). Here, if the threshold value Tth is set larger as Tth (1) in FIG. 5, the temperature detection result is obtained when the gap GA exists between the permeable resin member 22 and the absorbent resin member 24. In the case of the temperature curve CT (1), the temperature curve CT (1) is determined to be defective because there is a portion where the temperature curve CT (1) exceeds the threshold value Tth (1). In the case of 2), since there is no portion where the temperature curve CT (2) exceeds the threshold value Tth (1), it is erroneously determined that the welding state is good. On the other hand, when the threshold value Tth is set to a small value like Tth (2) in FIG. 5, the temperature detection result includes an overlapping portion with the temperature curve CTx (2) (CT (2) when the gap GA does not exist. ), The temperature curve CTx (2) is determined to be good because there is no portion exceeding the threshold Tth (2), but the temperature curve CTx (1) (CT ( 1), the temperature curve CTx (1) exceeds the threshold value Tth (2), so that the welding state is erroneously determined to be defective. As described above, in the method of the comparative example in which the quality of the welded state is determined by determining whether or not the entire temperature curve CT is equal to or less than the predetermined threshold Tth, there is room for improvement in terms of determination accuracy.

  In contrast, in the determination method of the present embodiment, the amount of change in the detected temperature during the effective period within the laser welding period, that is, the difference ΔT between the maximum value T (max) and the minimum value T (min) is equal to or less than the threshold value ΔT0. The quality of the welded state is determined by determining whether or not it is. Even if the temperature at the welding position during laser welding fluctuates due to the above-described factors, the degree of fluctuation is considered to be the same in the effective period of the laser welding period. Almost no effect. Therefore, in the determination method of the present embodiment, even if the temperature at the welding position during laser welding may fluctuate due to the above-described factors, the welding state can be accurately determined. As a result, for example, even when the welded portion is covered with the member to be welded and cannot be visually observed after laser welding, the welded state can be accurately determined in a non-destructive manner without adding special equipment. On the other hand, it is possible to prevent a good product from being judged defective and a yield from being lowered.

  In addition, since the determination method of a present Example performs determination using the variation | change_quantity of the detected temperature in the effective period of a laser welding period, it can determine a welding state with sufficient precision over the substantially whole welding locus | trajectory WL. Therefore, in the determination method of the present embodiment, the positional relationship between the members to be welded is not uniquely determined (for example, a cylindrical member or a member having a square plane), or the laser irradiation start position and the members to be welded are It is also suitable when the relationship with the position is not uniquely determined.

B. Second embodiment:
FIG. 6 is a flowchart showing the flow of welding state determination processing in the second embodiment. In the welding state determination processing in the second embodiment, the processing contents from reading of the temperature data (step S110) to noise removal processing (step S140) are the same as those in the first embodiment shown in FIG. Is omitted. In the following, the subsequent processing contents different from the first embodiment will be described.

  The determination device 18 differentiates the detected temperature in the effective period (the period from t1 to t2 in FIG. 4) in the laser welding period, and calculates the temperature change rate (change gradient) R (step S156). Next, the determination device 18 determines whether or not the maximum change rate value R (max) is equal to or less than a predetermined threshold value R0 (1) (step S166). If the maximum value R (max) of the change rate is greater than the predetermined threshold value R0 (1), the determination device 18 determines that the welded state is defective (step S180). On the other hand, when the maximum value R (max) of the change rate is equal to or less than the predetermined threshold value R0 (1), the determination device 18 further determines that the minimum value R (min) of the change rate is the predetermined threshold value R0 (2). It is determined whether or not this is the case (step S168). When the minimum value R (min) of the change rate is smaller than the predetermined threshold value R0 (2), the determination device 18 determines that the welding state is defective (step S180), and the minimum value R (min of the change rate) ) Is greater than or equal to a predetermined threshold value R0 (2), it is determined that the welding state is good (step S170). The predetermined threshold value R0 (1) is the maximum allowable threshold value for the change rate R, and the predetermined threshold value R0 (2) is the minimum allowable threshold value for the change rate R.

  When a gap GA exists between the permeable resin member 22 and the absorbent resin member 24 in a part of the welding locus WL, the detected temperature suddenly increases at a portion corresponding to the gap GA, or Since the temperature rapidly decreases, the change rate R of the detected temperature protrudes and increases or decreases. On the other hand, when such a gap GA does not exist, the change in the detection temperature is relatively gradual, so the change rate R of the detection temperature is unlikely to increase or decrease. Moreover, even if the temperature at the welding position during laser welding varies due to the factors described above, the degree of variation is considered to be the same in the effective period of the laser welding period. R is hardly affected. Therefore, it is determined whether or not the maximum value R (max) of the change rate R of the detected temperature is equal to or less than the threshold value R0 (1), and the minimum value R (min) of the change rate R is equal to or greater than the threshold value R0 (2). By determining whether or not there is a defect, it is possible to accurately determine whether or not there is a defective weld due to the presence of the gap GA.

C. Variations:
The present invention is not limited to the above-described examples and embodiments, and can be implemented in various modes without departing from the gist thereof. For example, the following modifications are possible.

  The configuration of the laser welding system 10 in the above embodiment is merely an example, and various modifications can be made. For example, in the above embodiment, the infrared sensor 14 is used to detect the temperature of the welding position, but a temperature sensor other than the infrared sensor 14 may be used. The sensor amplifier 16 can be omitted as appropriate.

  In the above embodiment, the temperature at the welding position is detected using a sensor during laser welding. However, other index values (for example, the amount of generated heat) correlated with the temperature at the welding position can be detected. It may be detected using a sensor.

  Further, in the above embodiment, among the temperature data, the data of the period when the temperature is unstable (the first predetermined period and the last predetermined period in the laser welding period) are discarded. Both data need not necessarily be discarded. When the temperature data of the first predetermined period is not discarded, the period from t0 to t2 in FIG. 4 becomes an effective period, and when the temperature data of the last predetermined period is not discarded, The period from t1 to te in FIG. 4 becomes an effective period, and when the temperature data of the first predetermined period and the last predetermined period are not discarded, the laser welding period (the period from t0 to te in FIG. 4) ) Itself is the effective period. In the above embodiment, the abnormal data masking process and the noise removal process using the low-pass filter are executed on the temperature data. However, one or both of these processes may not be executed.

  Moreover, in the said Example, although the welding locus | trajectory WL shall be substantially rectangular, this invention is applicable also when the welding locus | trajectory WL is other than substantially rectangular (for example, circular shape or linear shape).

  In the above embodiment, the difference ΔT between the maximum value T (max) and the minimum value T (min) is used as the amount of change in the detected temperature during the effective period of the laser welding period, but the maximum value is used as the amount of change. It is also possible to use a difference between T (max) and another reference value derived from the detected temperature in the effective period. Even if the difference between the maximum value T (max) and the other reference value is used as the amount of change, the welding state can be determined with high accuracy as in the above embodiment. In this way, even if an extremely low abnormal temperature value is detected, the amount of change in the detected temperature can be properly grasped. Examples of such other reference values include an average value of detected temperatures in the effective period.

  In the first embodiment, the welding state is determined using the detected temperature change amount ΔT. In the second embodiment, the welding state is determined using the detected temperature change slope R. By combining these, the welding state may be determined using both the change amount ΔT and the change gradient R.

DESCRIPTION OF SYMBOLS 10 ... Laser welding system 12 ... Laser irradiation apparatus 14 ... Infrared sensor 16 ... Sensor amplifier 18 ... Determination apparatus 22 ... Transmissible resin member 24 ... Absorbent resin member 26 ... Welding part

Claims (7)

In the laser welding state determination method for determining a welding state when joining a resin member that is transparent to laser light and a resin member that is absorbing to laser light by laser welding,
A step of detecting, using a sensor, the temperature or the amount of heat generated by exothermic melting at the welding position during laser welding;
Calculating at least one of the change amount of the temperature or the calorific value and the inclination of the change in a predetermined effective period of the laser welding period;
And a step of determining whether or not a calculated value is within a predetermined range for at least one of the change amount of the temperature or the calorific value and the inclination of the change. The laser welding state determination method according to claim 1,
The laser welding state determination method, wherein the change amount is a difference between a maximum value of the temperature or the heat generation amount in the effective period and a reference value derived from the temperature or the heat generation amount . The laser welding state determination method according to claim 2,
The laser welding state determination method, wherein the reference value is a minimum value of the temperature or the calorific value in the effective period. The laser welding state determination method according to claim 2,
The laser welding state determination method, wherein the reference value is an average value of the temperature or the calorific value in the effective period. A laser welding state determination method according to any one of claims 1 to 4,
The laser welding state determination method, wherein the effective period is a period obtained by removing at least one of a first predetermined period and a last predetermined period from the laser welding period. The laser welding state determination method according to any one of claims 1 to 5, further comprising:
A laser welding state determination method comprising a step of performing at least one of an abnormal data masking process and a noise removal process on the detected temperature or calorific value before the calculating step. In a laser welding state determination device that determines a welding state when a resin member that is transparent to laser light and a resin member that is absorbent to laser light are joined by laser welding,
A detection unit that detects the temperature or the amount of heat generated by heat generation and melting at the welding position during laser welding using a sensor;
A calculation unit that calculates at least one of a change amount of the temperature or a calorific value and an inclination of the change in the effective period of the laser welding period;
A laser welding state determination apparatus comprising: a determination unit that determines whether or not a calculated value is within a predetermined range for at least one of the change amount of the temperature or the heat generation amount and the inclination of the change.

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