JP4177548B2 - Processing method of weakened wire for airbag deployment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for processing a weakened wire portion for airbag deployment that is formed so as to be broken when the airbag is deployed on a vehicle interior material such as a steering handle cover or an instrument panel on which an airbag device is mounted on the back side.
[0002]
[Prior art]
Conventionally, as a method of processing a weakened line portion for airbag deployment, according to Japanese Patent Application Laid-Open No. 8-282420, a predetermined locus on which a weakened line portion is to be formed on the interior material in a state where the laser irradiation head faces the back surface of the interior material. So that the laser irradiation head and the interior material are moved relative to each other by an automatic machine so that the interior material is irradiated with laser from the laser irradiation head, and the surface of the interior material is perforated. There is known a method of forming a weakened line portion so as not to reveal. Here, if the thickness of the material remaining in the weakened line portion is large, the breakability at the time of deployment of the airbag is deteriorated, and if the residual material thickness is small, the weakened line portion is inadvertently broken normally. There is a possibility that it is necessary to accurately control the thickness of the remaining material. In the above publication, an ultrasonic sensor is attached to the interior material, the thickness of the remaining material in the weakened line portion is measured, and the thickness of the remaining material is controlled by feedback control of the laser output based on the signal from the ultrasonic sensor. However, it is difficult to accurately detect the thickness of the remaining material at the local processing spot irradiated with the laser at that time with an ultrasonic sensor. Yes, not practical.
[0003]
As a method for solving such a problem, a light receiving sensor facing the laser irradiation head with an interior material interposed therebetween is provided, and a trigger pulse is generated at regular intervals during the operation of the automatic machine, and the laser is synchronized with the trigger pulse. It is conceivable to irradiate the laser from the irradiation head and interrupt the laser irradiation until the next trigger pulse is generated when the output signal of the light receiving sensor reaches a predetermined level. According to this method, each time a trigger pulse is generated, laser irradiation is performed until a hole is made in the surface of the interior material and the laser is received by the light receiving sensor, and the processing location is reliably weakened. . Then, by appropriately setting the trigger pulse generation period, the overall intensity of the weakened line portion can be set to a predetermined value. By appropriately setting the predetermined level, the laser irradiation can be interrupted when an invisible fine hole is formed on the surface of the interior material, and the appearance of the interior material is not impaired.
[0004]
[Problems to be solved by the invention]
Even in the method of controlling the laser irradiation using the light receiving sensor as described above, the weakened line portion cannot be accurately formed if the operation speed of the automatic machine is deviated. In this case, it is conceivable to always monitor the movement of the automatic machine and to display an abnormality when the operating speed is out of order, but this complicates the processing.
[0005]
In view of the above points, the present invention provides a method for processing a weakened line portion that improves reliability by making it possible to easily discriminate an abnormality such as a deviation in the operating speed of an automatic machine. Is an issue.
[0006]
[Means for Solving the Problems]
In order to solve the above-described problems, the present invention is a method of forming a weakened line portion that breaks when an airbag is deployed in a vehicle interior material by laser processing, and the interior of the vehicle interior with the laser irradiation head facing the back surface of the interior material. The laser irradiation head and the interior material are moved relative to each other by an automatic machine so as to move at a constant speed along a predetermined locus on which a weakened line portion should be formed with respect to the material, and a predetermined pulse generator To generate a predetermined number of trigger pulses at regular time intervals during the operation of the automatic machine, irradiate the laser from the laser irradiation head in synchronization with the trigger pulse , and face the laser irradiation head with the interior material in between in that the output signal of the light receiving sensors provided has to interrupt the laser irradiation until the next trigger pulse was increased to a predetermined level is generated, the automatic machine, the weakening Generate an operation end signal when part is moved over the entire length of the predetermined path to be formed, to said operation end signal from the last trigger pulse is generated for the predetermined number of trigger pulses are generated Is measured, and when this time deviates from a predetermined allowable range, it is diagnosed that there is an abnormality.
[0007]
A predetermined number of trigger pulses are generated in advance according to the length of the weakened line portion during operation of the automatic machine. If the automatic machine operates normally without causing a speed fluctuation, the time taken from the generation of the predetermined number of last trigger pulses to the generation of the automatic operation end signal is within a predetermined allowable range. If this time deviates from the allowable range, it can be determined that the operation speed of the automatic machine has become unstable.
[0008]
It is also possible to diagnose the presence or absence of abnormality based on the operation time taken from the start of operation of the automatic machine to the end of operation, but in this case, the allowable range of operation time is set according to the length of the weakened line part. Must be set. And if the length of the weakening line part is changed by changing the model of the interior material, it is necessary to reset the allowable range. On the other hand, when diagnosing the presence / absence of an abnormality based on the time taken from when the last trigger pulse is generated to when the automatic machine operation end signal is generated as in the present invention, By simply resetting the number of trigger pulses generated in accordance with this, it is not necessary to reset the allowable range for abnormality diagnosis, and preparation work when changing the model becomes easy.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Referring to FIG. 1, reference numeral 1 denotes a vehicle interior material including an instrument panel. The interior material 1 is formed with a contour of a region facing the airbag device 2 mounted on the back side of the interior material 1 and a weakening line portion 3 along a center line that bisects the region. Is broken, and the portion surrounded by the weakened line portion 3 is opened as a pair of lids 4 and 4. Moreover, the hinge plate 5 which connects each lid 4 to the part of the exterior interior material 1 is attached to the back surface of the interior material 1 to prevent the lid 4 from scattering when the airbag is deployed. The interior material 1 includes a first fixing plate 6 so as to surround a region facing the airbag device 2, and a pair of second fixing plates 7 and 7 positioned on both sides of the center line of the region. Are embedded in the fixing plates 6 and 7, bolts 6 a and 7 a projecting from the back surface of the interior material 1 are implanted, and the airbag device 2 and the hinges are bolted by the bolts 6 a implanted in the first fixing plate 6. The outer edge of the plate 5 is fixed to the interior material 1, and the inner edge of each hinge plate 5 is fixed to each lid 4 by a bolt 7 a planted on each second fixing plate 7.
[0010]
The interior material 1 has a three-layer structure including a resin base 1a on the back side, an intermediate foam layer 1b, and a resin skin 1c. When the interior material 1 is manufactured, after the base material 1a and the skin 1c are respectively resin-molded, the bolts 6a and 7a are formed in the bolt holes 8 formed in the base material 1a in the resin molding process as shown in FIG. Insert the first and second fixing plates 6 and 7 on the base material 1a, set the skin 1c and the base material 1a in the mold in this state, and foam between the skin 1c and the base material 1a. A foamed layer 1b is formed by injecting a resin to cause foaming. After the molding of the interior material 1 is completed in this way, the weakened wire portion 3 is formed on the interior material 1 as shown in FIG. 2B, and finally, bolts 6a and 7a are used on the back surface of the interior material 1. As shown in FIG. 2C, the pair of hinge plates 5 and 5 and the airbag device 2 are attached.
[0011]
FIG. 3 shows a processing facility of the weakened line portion 3. This processing equipment includes a handling robot 100 that holds the interior material 1, a CO ₂ laser oscillator 101, and a fixed laser irradiation head 103 that enters a laser from the laser oscillator 101 through a mirror 102. The material 1 is held so that the laser beam from the laser irradiation head 103 is irradiated on the back surface, and in this state, the laser irradiation head 103 is constant along a predetermined locus on which the weakened line portion 3 is to be formed with respect to the interior material 1. The interior material 1 is moved relative to the laser irradiation head 103 by the handling robot 100 as an automatic machine so as to move at a speed. The laser irradiation head 103 can be moved by an automatic machine such as a robot instead of the interior material 1. In FIG. 4, reference numeral 104 denotes a main controller. After an activation signal is input from the robot controller 105 of the handling robot 100 to the main controller 104, a trigger pulse is generated from the main controller 104 at regular time intervals as shown in FIG. As a result, the laser oscillator 101 is operated via the flip-flop 106 and the laser controller 107.
[0012]
Further, when the light receiving sensor 108 facing the laser irradiation head 103 with the interior material 1 interposed therebetween is provided and the output signal of the light receiving sensor 108 is input to the comparator 109, the output signal of the light receiving sensor 108 rises to a predetermined level. The comparator 109 generates a high-level signal that is an interruption signal, and the output signal of the flip-flop 106 is inverted by this signal, and the laser controller 107 stops the operation of the laser oscillator 101. Thus, in synchronism with the trigger pulse, the laser irradiation head 103 irradiates the interior material 1 with laser, the material of the interior material 1 is burned out from the back side, and finally a hole is made in the skin 1c, and this is received by the light receiving sensor 108. laser has reached through the hole, the output signal of the sensor 108 is a laser irradiation is interrupted until the next trigger pulse where elevated to a predetermined level is generated. Therefore, as shown in FIG. 4B , the weakening line portion 3 whose depth periodically changes is formed in the interior material 1. There is a slight response delay from the time when the output signal of the light receiving sensor 108 rises to a predetermined level until the laser irradiation is stopped, and the hole in the epidermis 1c increases during that time, but the predetermined level is in the order of microns. The level is set to the level when the hole is opened, and even if the hole diameter increases due to a delay in response, it does not have a size that can be visually observed, and the appearance of the interior material 1 is not impaired. The laser controller 107 functions to initially increase the laser output and then decrease the laser output when a high-level drive signal is input from the flip-flop 106 by the trigger pulse. Prevents holes from being drilled.
[0013]
In addition to the signal from the robot controller 105, the main controller 104 receives the output signal of the light receiving sensor 108 and the output signal of the comparator 109. Based on these signals, the main controller 104 performs abnormality diagnosis processing. It is carried out. The details of the abnormality diagnosis process are as shown in FIG. 5. First, it is determined whether or not a trigger pulse is generated (S1), and when the trigger pulse is generated, the time measurement of the first timer is started (S2). Then, it is determined whether or not the trigger pulse is the last trigger pulse generated in a predetermined number during the processing of the weakened line portion 3 (S3), and if it is the last trigger pulse, the time measurement of the second timer is started ( S4). Next, it is determined whether or not a high level signal, that is, an interruption signal is generated from the comparator 109 (S5), and when the interruption signal is generated, the time count TM1 of the first timer at that time is stored. After that, the first timer is reset (S6). In addition, after the time count TM3 of the third timer at the time of generation of the interruption signal is stored, the time measurement of the third timer is started after the third timer is reset (S7). Further, the count value C of the number of occurrences of the interruption signal is updated to a value obtained by adding 1 to the previous value (S8), and the peak value PH of the current output signal of the light receiving sensor 108 is detected and stored (S9).
[0014]
Next, it is determined whether or not the time measured TM1 of the first timer stored in step S6 is not less than a predetermined lower limit value YTM1L and not more than a predetermined upper limit value YTM1H (S10), and TM1 is YTM1L and YTM1H. If it deviates from the permissible range, a diagnosis is made that there is an abnormality, and a message to that effect is displayed, and the subsequent machining is stopped (S11). Here, TM1 is equal to the processing time taken from the time when the trigger pulse is generated, that is, from the start of laser irradiation until the output signal of the light receiving sensor 108 rises to a predetermined level and the interruption signal is generated. As shown in FIG. 6A, the processing time TM1 falls within an allowable range if the depth from the back surface, which is the laser incident surface of the interior material 1, to the focal position of the laser is appropriate, but the focal position is the same as that shown in FIG. If it becomes too shallow as shown in B), the burning rate of the material becomes faster due to an increase in the energy density at the laser incident surface, falls below the lower limit YTM1L, and the focal position becomes too deep as shown in FIG. The burning rate of the material becomes slow and exceeds the upper limit value YTM1H. The width of the weakened line portion 3 becomes narrower when the focal position becomes shallower and becomes wider as the focal position becomes deeper. Therefore, in order to form the weakened line portion 3 with an appropriate width so as to have a required strength, it is necessary to control the handling robot 100 so that the depth of the focal position is appropriate. However, the depth of the focal position may become inappropriate due to an error in the control accuracy of the handling robot 100, an adjustment error in the laser irradiation head 103, or the like. Therefore, when TM1 deviates from the allowable range, it is determined that the depth of the focal position is inappropriate and abnormal display is performed. When TM1 deviates from the allowable range, it is possible to perform feedback correction of the handling robot 100 so that the depth of the focal position becomes appropriate.
[0015]
If the discrimination process based on the machining time TM1 is performed as described above, then whether the time measured TM3 of the third timer stored in step S7 is equal to or greater than a predetermined lower limit value YTM3L and not greater than a predetermined upper limit value YTM3H. (S12), if TM3 deviates from the allowable range between YTM3L and YTM3H, it is diagnosed that there is an abnormality and displays that fact, and the subsequent machining is stopped (S13). . TM3 is the time measured at the time when the current interrupt signal is generated by the third timer, which has started counting from the time when the previous interrupt signal is generated, and represents the time interval at which the interrupt signal is generated. By the way, when the pitch of the holes opened on the surface of the interior material 1 is shortened, the amount of the remaining material remaining between the holes is decreased, the strength of the weakened line portion 3 is decreased, and the pitch of the holes is increased. The strength of the weakened line portion 3 is increased. Therefore, in order to form the weakened line portion 3 to have a required strength, it is necessary to appropriately manage the pitch of the holes. However, the hole is generated due to a fluctuation in the generation period of the trigger pulse and the operating speed of the handling robot 100. The pitch may be incorrect. Here, when the generation period of the trigger pulse goes wrong, the generation time interval TM2 of the interruption signal also changes accordingly, and when the operating speed of the handling robot 100 becomes slow, the material in the vicinity of the punched portion is greatly burned out. The next laser irradiation is started at the part, and a hole is opened early, and the generation time interval TM3 of the interruption signal is shortened. Therefore, when TM3 deviates from the allowable range, it is judged that the pitch of the holes has become inappropriate due to the generation period of the trigger pulse or the operating speed of the handling robot 100, and the abnormality display is performed.
[0016]
Once the determination process based on the interruption signal generation time interval TM3 is performed as described above, it is then determined whether or not the peak value PH stored in step S9 is equal to or less than a predetermined upper limit value YPH (S14). The peak value PH is a value when the output signal of the light receiving sensor 108 is maximized due to a response delay from when the interruption signal is generated until the laser irradiation is interrupted. This is a parameter that represents the diameter. When PH> YPH, the size of the hole is visible. Therefore, in this case, it is diagnosed that there is an abnormality, a message to that effect is displayed, and the subsequent machining is stopped (S15). In this embodiment, the peak value PH is used as a value representing the intensity of the output signal of the light receiving sensor 108. However, when the waveform area exceeds the predetermined value, the peak area PH is used. Display may be performed.
[0017]
When the discrimination process based on the output signal intensity of the light receiving sensor 108 is performed as described above, it is next discriminated whether or not an end signal is input (S16), and the process returns to the step S1 until the end signal is input. The above discrimination process is repeated. The end signal is generated from the robot controller 105 when the laser irradiation head 103 is moved over the entire length of a predetermined locus on which the weakening line portion 3 is to be formed with respect to the interior material 1. When the end signal is input to 104, the time count TM2 of the second timer at that time is stored, and then the second timer is reset (S17). Since the second timer starts timing when the last trigger pulse is generated, TM2 represents the time taken from when the last trigger pulse is generated until the end signal is generated. When the handling robot 100 operates normally and the laser irradiation head 103 is moved at a predetermined speed along a predetermined locus with respect to the interior material 1, TM2 should be within a predetermined allowable range. Therefore, the lower limit value and the upper limit value of the allowable range are set as YTM2L and YTM2H, respectively, and it is determined whether or not YTM2L ≦ TM2 ≦ YTM2H (S18). A diagnosis is made and a message to that effect is displayed (S19).
[0018]
Further, when the weakening line portion 3 is processed normally without causing an abnormality such as a generation cycle of the trigger pulse or an operating speed of the handling robot 100, or an abnormal laser irradiation failure, the weakening line portion 3 is processed. The total number of holes is a predetermined value. Therefore, it is determined whether or not the count value C of the rotation of the interruption signal indicating the number of punched portions is a predetermined value YC (S2D), and if C ≠ YC, it is diagnosed that there is an abnormality and that fact is determined. Is displayed (S21), and when it is determined that C = YC, it is displayed as passing (S22).
[0019]
As described above, the embodiment in which the present invention is applied to the method of forming the weakened wire portion 3 on the interior material 1 including the instrument panel by laser processing has been described. However, the airbag is applied to other interior materials for vehicles such as a steering handle cover. The present invention can be similarly applied when the weakened line portion is formed by laser processing.
[0020]
【The invention's effect】
As is clear from the above description, according to the present invention, when an abnormality such as a deviation in the operation speed of the automatic machine occurs, this can be easily determined, and the reliability can be improved at a low cost. Preparation work is also facilitated.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of an interior material with an airbag device attached thereto.
2A is a perspective view showing an assembled state of a fixing plate to a base material of an interior material, FIG. 2B is a perspective view showing a processing step of a weakened line portion, and FIG. 2C is an assembly of an airbag device and a hinge plate; The perspective view which shows a process.
FIG. 3 is a schematic side view of processing equipment at a weakened line portion.
FIGS. 4A and 4B are time charts showing changes in various signals in the processing of the weakened line portion, and FIG. 4B is an enlarged cross-sectional view along the longitudinal direction of the weakened line portion.
FIG. 5 is a flowchart showing a program for abnormality diagnosis.
6A is a diagram showing a cross-sectional shape and processing time of the weakened line portion when the focal position of the laser is appropriate, and FIG. 6B is a cross-sectional shape and processing time of the weakened line portion when the focal position is shallow. (C) The figure which shows the cross-sectional shape and processing time of a weakening line part when a focus position is deep.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Interior material 2 ... Airbag apparatus 3 ... Weakening line part 100 ... Handling robot (automatic machine)
103 ... Laser irradiation head 108 ... Light receiving sensor TM2 ... Time from the last trigger pulse to the end signal generation

Claims (1)

A method of forming a weakened line portion that breaks when an airbag is deployed in an interior material for a vehicle by laser processing,
One side of the laser irradiation head and the interior material is moved so that the laser irradiation head moves at a constant speed along a predetermined locus on which the weakened line portion should be formed with respect to the interior material in a state where the laser irradiation head faces the back surface of the interior material. And a predetermined number of trigger pulses are generated at regular time intervals during operation of the automatic machine by a predetermined pulse generator , and a laser is irradiated from the laser irradiation head in synchronization with the trigger pulse, The laser irradiation is interrupted until the next trigger pulse is generated when the output signal of the light receiving sensor provided to face the laser irradiation head across the interior material rises to a predetermined level.
The automatic machine generates an operation end signal when moved over the entire length of a predetermined path on which the weakened line portion is to be formed,
Wherein said operation end signal end of the trigger pulse of a predetermined number of trigger pulses from being generated by measuring the time taken until the occurrence, the time is diagnosed that there is abnormality when the deviation from the predetermined allowable range A method for processing a weakened wire portion for airbag deployment, characterized in that:

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