DE19949501A1 - Inserting cavities in plastic material, e.g. to produce line of weakness in airbag cover, uses laser controlled by sensor analyzing material condition - Google Patents

Abstract

A laser (4) is used to produce cavities (2) in a plastic material (3). Electromagnetic radiation (8) from a source (7), e.g. another laser, impinges on the material surface (12) and the transmitted radiation (28) is detected by a sensor (9). The signal is used to control the operation of the cutting laser (4). A further sensor (10) to detect transmitted radiation from the cutting laser (4) can assist in controlling the depth of cut. Alternatively only one laser (4) is used to combine both functions.

Description

The invention relates to a method for making depressions in plastic parts by means of a controllable radiation source according to the preamble of claim 1.

The making of recesses in plastic parts is in the field of automotive engineering among other things in the manufacture and structuring of the dashboards from greatest interest. Especially the installation of so-called invisible airbags in Dashboards require a well-defined structure of the airbag cover in the Area of the dashboard to ensure a uniform in series production To ensure the functional behavior of the airbags.

An airbag is deployed in the event of strong braking accelerations due to an accident of a vehicle. These braking accelerations are measured and electronically evaluated. If certain limit values are exceeded, the Airbag system by igniting an explosive. The airbag is closed at this time still folded in the dashboard. This is in the Dashboard incorporated a recessed recess. This recess is one Airbag cover closed. The explosive is still in the airbag. The Explosion causes a cloud of gas from combustion gases. Through this yourself expanding gas cloud builds up pressure inside the airbag. The pressure of Gas cloud inflates the airbag. By inflating the airbag in the form of a Air cushions unfolded from the dashboard into the passenger compartment. At the The airbag cover of the dashboard inflates into the passenger compartment torn open. When inflated, the air cushion is used for cushioning. The, due to the braking deceleration of the vehicle, passenger accelerated relatively forward falls with the upper body into the inflated airbag. This will impact the Passengers on the dashboard prevented.

The pressure builds up with one by the type and amount of the used Explosive time and strength. This process must take place within one certain time. The amount and type of explosive within of the airbag is standardized for the respective airbag type.  

To cut costs, the auto industry has switched to manufacturing methods which involve outsourcing the manufacture of accessories. Because of the different Raw material, tool and component suppliers are involved in the manufacture of the Accessories for a spread in the dimensions of the manufactured components.

Dashboards and their starting products are also of this dimensional variation affected.

It is therefore the task of a method for making recesses in Develop plastic parts, which ensures that the tear behavior of the Airbag cover from the dashboard on all dashboards in a series is similar.

This object is achieved with the features of main claim 1.

The invention has recognized that it is for the same tear behavior of all Airbag covers in the respective dashboard type is necessary that the Airbag cover in the dashboard the structural and mechanical requirements the airbag spread must be adjusted. The invention means that Tear open the airbag cover uniformly for one certain dashboard type must be predictable. The invention Tear open behavior of the airbag covers virtually standardized.

The invention has solved the problem of the uniform spreading of the airbag in the Passenger interior for all vehicles with a certain dashboard type ensure. Because only with a similar tear behavior is an optimal and similar protection is guaranteed for all vehicles. The specification according to the invention The tear-open property of the airbag cover is done by a controlled one Manipulation of the material structure. With this controlled manipulation, the material specifically weakened in terms of its tensile strength and direction. This Material weakening is achieved in the material of the airbag cover Wells are introduced. The wells are on the side in the Airbag cover introduced, which should face the airbag. This bringing in can be done mechanically, thermomechanically, thermo-optically or chemically.

The invention has recognized that thermo-optical processing in combination with a control unit and an evaluation unit are inexpensive and  represents an efficient method because of the rapid processing of the airbag cover. Especially with the combination of lasers for processing and material determination as well as sensors matched to the laser for monitoring and with one on it coordinated computer system with fixed response times (preferably in Millisecond range or shorter), the invention discloses a fast and flexible Machining processes.

The advantage of the invention results from a manageable uniform Tear-open behavior of the airbag covers, even if the material composition and strength varies from dashboard to dashboard. This is done by the Control and control of the depth reached during laser processing. This will the comparison value for this check at least for each dashboard separately given. This applies analogously to every depression to be lasered in everyone Dashboard.

The invention describes a method for making depressions in Plastic parts by means of a controllable radiation source, in which the Plastic material of the dashboard airbag cover with one of the Composition and thickness of the plastic material according to the irradiation power of the Radiation source is processed. In a preferred embodiment of the invention controllable radiation source that introduces the wells, a laser. In another This laser is designed with a control unit that passes through the material passing light measures, controls and when a predetermined one is reached Intensity value switched off. Reaching the intensity value is considered to have been reached Interpreted depth. The circumferential shape of the indentation is determined from the exit form at the laser source for the laser beam. By shaping the Exit opening for the laser beam can be the circumferential shape of the to be introduced Deepening on the tear property and the material behavior.

The invention also solves the problem of dimensional fluctuations. These dimensional fluctuations arise z. B. by manufacturing a dashboard type on different Machine tools. These machine tools can do even one Suppliers from various machine tool manufacturers. This effect understandably amplifies when the accessories from multiple suppliers be delivered. The effect can now, through material determination and knowledge around the absorption capacity of the material. Because the invention has recognized that although the plastic material when processing  Dashboard to dashboard can make these distinctions through skillful material examinations but with reasonable effort sufficiently quickly can be determined. After determining the material composition can then again due to the absorption behavior on the material thickness be inferred. The invention has recognized that this conclusion is a Adaptation of the laser enables. This adjustment is made by setting the Burn-in time or the light output or a combination of both. Through this The burn-in depth is adjusted to the material thickness and the tear properties set.

Laser technology proves to be well applicable, since it only lasts for a short leads to violent and locally limited heating of the material. The brought in Thermal energy is almost completely converted during the evaporation of the material. As a result, only little heat diffuses into the surrounding material. As a result, Plastic material both thermochemical and thermal-molecular Changes reduced. The invention thus improves the Structural stability in the non-lasered area. The invention solves by application The problem with the laser is that of simply machining an airbag cover is caused by heat. The use of heat does not necessarily guarantee that Removal of material necessary for weakening. Will the material through the Applying the heat hot and therefore plastic, this can be more likely Material displacements and deformations lead because when the heat is introduced Part of the material may move sideways and upwards. This has the disadvantage that uncontrolled stiffeners and reinforcements are stamped / melted into the material become. The invention has recognized that this material shift in the application according to the invention because of the narrow limitation of the laser beam in Space and time is next to impossible. In addition, the invention has recognized that a pulsating laser beam is both easier to control and has the advantage that the heat diffusion into neighboring areas is further reduced. The invention thus prevents the tear behavior by simply applying heat to the Airbag cover changed to uncontrollability. In addition, the Invention the thermal changes caused by the diffusing heat in the molecular structure of the polymers, such as winding, twisting, folding etc. reduced that they have practically no mechanical influence.

The invention has recognized that the optical properties of the plastic material can vary. This variation occurs e.g. B. by a fluctuation in the  Composition and distribution of the masterbatch in the plastic introduced color pigments, as well as the spatial orientation of the polymers. The Invention has further recognized that these variations in composition that then special light absorption properties for each individual dashboard cause can be used for material determination.

The invention solves the problem that the fluctuations in the optical Properties of the operation of a laser system for normalized structure weakening by means of indentations becomes difficult. The invention uses the fluctuations Troubleshooting. The invention solves the problem that with fixed laser power different absorption properties lead to different depressions. The Absorption properties do not have to match the mechanical properties related. The invention controls the insertion of the wells depth currently reached. For this, she uses the laser light used. This is highly concentrated light. The invention takes advantage of the fact that the plastic material Airbag cover in the material thickness as it is in the production of Dashboards are used slightly for the laser light used is permeable. This permeability is also given when the airbag cover is colored deep black. The invention has recognized that this permeability for Laser light can be evaluated by measurement. The invention evaluates, among other things, the measured amount of transmitted laser light and uses this information then for depth control. The invention has recognized that by Intensity measurements of the transmitted light can thus be determined how far the laser is in irradiated the material. The laser processing of the material according to the invention for Structural weakening and the resulting control of the tear properties of the Airbag coverage is done with a laser control based on the control unit that measures the light passing through the material. The laser beam is applied to the Material side directed to the airbag. On the opposite In the material direction, there is a sensor in the beam direction for measuring the intensity of the translucent light. The laser beam begins with the indentation in the airbag cover. At the same time, the sensor begins to measure the strength of the material or residual material to transmit the laser beam. This measured value is compared according to the invention with a predetermined comparison value. This The comparison value was with the material test carried out according to the invention determined. After the determination, it is then sent to a comparison unit circuit given. The comparison process belonging to the inventive method can be carried out in a integrated in the sensor or in a separate comparison circuit or by means of a  connected data processing system. The measurement method The data transferred is processed by the laser according to the burn-in duration Evaluation unit evaluated in real time. Real time means that data acceptance, Data processing and data output or reaction control within certain predetermined time intervals in the millisecond or microsecond range guaranteed to be adhered to. When the specified one is reached Comparative value, the laser is switched off. The comparison value is reached in doing so as reaching a certain depth when introducing the depression interpreted the laser beam in the airbag cover. The invention thus uses that Problem of light attenuation when the light passes through the material as Approach for depth control. The problem with a laser control with a solid, not matched to the specific material composition, predetermined irradiation power or a fixed time at a fixed Laser power per time is avoided by the invention.

When laser processing the airbag cover with a defined laser power per time for a specific set not on the specific material composition coordinated time unit with a laser beam is the depth of the recess not predictable.

According to the invention, the insertion depth is controlled. The each achieved Depth can be detected at any time during the laser process. A result check thus does not take place only after completion of the laser processing or at one Interruption but can go on throughout the period of the deepening process if necessary for each individual recess and in fractions of a millimeter I agree.

The application of the invention also provides a solution for the plastics that regardless of different polymer composition, despite different Absorption properties have the same mechanical properties. Because with firmer Irradiation power through the laser into the plastic would be a variance of Tear-off properties generated by the processing. This variance in the Tear-off property results from the different material removal that results from the different absorption behavior. With poor absorption thus only a small amount of material is removed and vice versa. The same would result with a predefined comparison value for depth control in the control unit, which measures the light passing through the material.  

With some plastics, increasing proportions of the masterbatch increase Absorbency, which goes hand in hand with decreasing mechanical strength. The processing of these plastics according to the invention avoids otherwise given irradiation power either too weak or too weak tearing open airbag covers.

The change in the composition causes a fluctuation in the lengths and the linkages of the polymers. The fluctuations in lengths and Links establish a fluctuation in the tearing behavior. The Variations in the length of the polymers cause various minor changes other types of linking of the polymers to one another, but which affect the can have mechanical behavior. A high percentage is required for high tear resistance long-chain polymers necessary. The long-chain polymers are depending on Manufacturing process pretty much parallel. This parallel alignment then gives u. a. the preferred tear direction, but this is not always identical to the desired one. Therefore, a preferred is for a uniform tear behavior of the airbag cover To aim for tear direction. The invention therefore also solves the problem that this preferred tear direction introduced by the manufacturing side when tearing open the Airbag cover affect the spreading of the airbag into the passenger compartment could. To ensure adequate and even airbag deployment The polymers have to ensure coordinated tensile strength in all directions be cross-linked accordingly. For these cross-links, however, are again special polymers and polymer lengths also require their composition is subject to minor but effective fluctuations. The Use of the laser system according to the invention also eliminates these difficulties, since the Color additives incorporated into the material in addition to the optical properties also change the structure of the polymer compounds.

The invention has recognized that to ensure one for all dashboards one Series of similar tearing properties of the airbag cover a single analysis of the dashboard to be machined is advantageous. For analysis electromagnetic radiation onto the rear surface of the airbag Airbag cover steered. The electromagnetic rays are with their Angle of incidence, their intensity, their polarization and their spectrum are known. The Analysis of the composition of the plastic part is done by measuring the  electromagnetic radiation from the surface of the part to be examined goes off.

A possible method of measurement to determine the surface of the examined Measuring outgoing electromagnetic radiation from plastic parts uses the reflected part. This can be done on the reflected part of the radiation Absorption spectrum, the change in polarization or the Brewster angle, if necessary, also determine the reflection coefficient. The measured values determined are compared with the comparison values known from laboratory tests. The values can then be compared or interpolated tax data required for the respective material to introduce the wells determine. The comparative values determined in the laboratory tests can be used stored as data for program-based further processing in a computer system his. Another possibility is the implementation of the comparative values from the laboratory in Voltage / current values. This has the advantage that this is immediately in one electrical comparison circuit can be used.

Another possible measurement method uses the transmitted light on the Plastic material side attached a measuring device. The measuring device is located on the side opposite to the entrance side of the electromagnetic rays. On This measuring device can, for example, record the following measured values: how Absorption spectrum, refractive index, polarization and drop in intensity; at the A drop in frequency can be used to examine the drop in intensity become. Individuals or combinations of measured values can then be Comparison with those determined in the laboratory and stored in a data processing system Comparative values determine the material composition. The evaluation of the The material composition then determines the material properties and the Relationship between absorbency and mechanical properties such as Tear resistance and preferred tear direction. This in turn becomes the necessary Control data for introducing the recesses for the respective dashboard certainly. The evaluation can also be done directly via a hardware implementation Laboratory values in voltage and / or current comparison circuits are made as described above.

In one embodiment of the invention, two different radiation sources went out. A source of electromagnetic radiation is with a measuring sensor coupled. This is used to examine the material composition. To do this  a z. B. used laser-based analyzer. The analysis is carried out on a laser system positioned on the airbag side and one on the other material side in Direction of radiation held measuring sensor. The measuring sensor takes the intensity values of the transmitted laser light. The laser system does not have to be a single one Laser light source exist. It is possible to use several different color lasers couple. This has the advantage of frequency-dependent in a simultaneous operation Obtain measured values of the transmitted light.

Another possibility is to use one as an analysis laser frequency-shiftable / controllable laser to use. During the duration of Insertion of the wells in the plastic material is time enough with such Laser to carry out the measuring process for different frequencies one after the other and forward the measured values to the data processing system / comparison circuit.

With the other radiation source, here a laser, the recesses in the Material introduced. It is coupled to a sensor. The sensor sits in Direction of radiation on the other side of the material. It is used to measure the intensity of the translucent light. The sensor measures this by the residual thickness of the material light passing through. The measured value is sent to a Comparison circuit / data processing system forwarded. As soon as the measured Value for the transmitted light reaches a certain comparison value, the Laser switched off. The comparison process of the values can be done in the sensor or a Evaluation circuit or a connected computing system. The The result of the comparison process then delivers a signal to the evaluation Laser.

However, it is also conceivable that a radiation source is used for the deepening, which also carries out the analysis of the material composition. This is particularly useful Begin when a laser is used to make the recess. The laser provides one known with the intensity, polarization, frequency and angle of incidence electromagnetic radiation. This radiation can be on the back of the material with regard to their drop in intensity, their rotation of the plane of polarization and the Refraction can be detected when the material is irradiated. Is the laser in his Beam direction freely positionable and the sensor in beam direction accordingly trackable, the Brewster angle can also be determined. The measured values are only required once per dashboard, under which Prerequisite that a homogeneous material composition for a certain  Area is present. Sufficient three to four measured values are thus available Available to recognize the material in its composition. As another Control value lends itself to the insertion depth per Evaluate time unit. It becomes a constant and known radiation energy provided. These measured values are continuously measured in the beam direction on the sensor positioned on the opposite side of the material Data processing system transmitted. There is real time using fuzzy logic algorithms based on the composition of the material of the airbag cover determined. The tax data for the Introduce the depression. These are then the determined values for the Adjusted composition and passed on to control the laser. The further then works analogous to the description above. As already described above, can the measured values, voltage or current in Comparison circuits can be stored and evaluated.

There is a certain fluctuation in the material thickness of the individual dashboards expect. The measured values of decrease in intensity, change in polarization and The refractive index then has a corresponding fluctuation range. Therefore are all comparison values not as absolute values in the data processing system saved, but as approximate comparison values, the comparison value sets. The Measured values are because there is no information about the material thickness of the airbag cover are available, mapped to the comparison value sets, which the possible Take material thickness into account. These images are fuzzy Logic algorithms processed further in terms of information technology. Fuzzy logic algorithms deliver on the comparison of shown measured value sets with the Comparative quantities approximately to exactly the material composition of the Airbag cover at the examined point. The comparison values come from Laboratory tests. The laboratory tests are for different Material compositions and thicknesses measured the material determining values been. The determined values are then in comparison value sets or Comparison circuits have been filed.

The evaluation is carried out using the so-called fuzzy logic. This so-called fuzzy The purpose of logic is to arrive at decision rules that are in a Data processing system can be used if the data to be processed is none allow clear statement and / or assignment. Both are here because of the missing  Information about material thickness given. Therefore, there are no absolute, sharp ones here "if then. . ." To make decisions.

To put it simply, colloquialisms are used to solve problems Tolerance principles: "The part is very good, that's good, is still possible, that only with reservations, that is no longer tolerable "in an evaluation algorithm Such evaluation algorithms are then created from the Measured values / measured value ranges and the roughly assigned material composition the corresponding mechanical properties Control data obtained for the controllable radiation source, for example laser optics.

The invention is explained in more detail below on the basis of exemplary embodiments.

Fig. 1 Laser hole conditioning with separate measuring device,

Fig. 2 laser hole system with integrated measuring device,

Fig. 3 dashboard sketch with the airbag cover,

Fig. 4 cross-section IV-IV of FIG. 3 by the dashboard,

Fig. 5 laser punching system (circuit diagram).

The figures show a method for introducing depressions 2 into plastic parts 3 by means of a controllable radiation source 4 . For this purpose, incoming electromagnetic rays 8 are directed onto the surface 12 of the plastic part 3 . The plastic part 3 is an airbag cover according to FIG. 3. Such an airbag cover 3 is part of the dashboard 17 . Above is the outbreak of the windshield 44 adjoining the dashboard. The depressions 2 located on the airbag side are indicated on the airbag cover. The production of these depressions is the subject of this present invention.

FIG. 4 shows a cross section through the dashboard 17 in the region of the airbag cover 3 , which has an inside provided with depressions. The folded airbag 18 can be seen in the interior below the airbag cover 3 . Below the airbag 18 is the detonator 19 , which inflates the airbag 18 through its explosion gases if necessary. When this is necessary, the airbag cover 3 tears open due to the inflating airbag 18 . The tearing occurs at the sections of the airbag cover 3 provided with the depressions 2 in the dashboard 17 .

In Fig. 4a, the enlarged detail of the area designated with "I" of the machined airbag cover 3 can be seen. It can be clearly seen that the plastic part 3 is provided with depressions 2 . The depth 23 of the depression 2 and residual wall thickness 15 of the plastic add up to the total wall thickness 22 . The remaining wall thickness 15 and the depth 23 of the recess 2 depend on the material. In accordance with the mechanical properties of the material and the desired tear-open property of the airbag cover 3 , the remaining wall thickness 15 and the insertion depth 23 of the respective material composition and material thickness 22 of the airbag cover 3 in the dashboard 17 are adapted. In the present case, this is done by detecting a measurement variable which is dependent on the composition of the plastic material and is a component of the outgoing electromagnetic radiation ( 28 ) and converting it into a control signal which is used to control the radiation power of the controllable radiation source ( 4 ).

This is shown in Fig. 1 shows the enlarged detail of the region indicated by "I" in FIG. 4. The labeled "I" field is displayed in the editing phase. It shows a part of the dashboard 17 and a laser perforation system 1 is positioned above it. The partial section of the airbag cover 3 is made of plastic. The section "I" is shown as a longitudinal cross section with, from right to left, recess 2 , recess 24 being processed and planned recess 25 . The laser punching system 1 consists of a device for carrying out the method with a source for electromagnetic radiation 4 , an analysis device for determining the measurement variable dependent on the plastic material by means of the electromagnetic radiation 28 emanating from the surface 12 of the plastic part 3 , and a device for evaluating the measurement variable and determining control data for a controllable radiation source 4 for introducing the depression 2 and a measuring device 10 for controlling the introduction of the depression 2 .

The controllable radiation source 4 has a measuring device 10 , here in the form of an intensity sensor 10 . The control device consists of a data processing system 5 , the data bus 11 and the control lines 13 and 14 . The data processing system 5 is connected to the measuring unit via the data bus 11 and the control line 14 and to the radiation source 4 via the control line 13 . The control lines 13 and 14 can also be serial or parallel data buses. The measuring unit consists of a source of electromagnetic radiation 7 and a measuring device 9 for determining the residual radiation 28 which emanates from the airbag cover 3 . In the drawing, the measuring unit is positioned over the planned recess 25 .

The measuring unit is used to analyze the plastic on the planned recess 25 . However, it is conceivable that the measuring unit is only used once to determine the composition of the plastic of the airbag cover 3 , because the homogeneity in the material composition is sufficient to the extent that fluctuations have no influence on the mechanical properties.

The source 7 for electromagnetic radiation can be a multi-spectrum lamp with or without a polarizer, several monochromatic lasers, a gas or solid laser with adjustable, variable laser light wavelength, a source for soft or hard X-rays and / or a source for electron beams. The source 7 can be mounted on the same side as the radiation source 4 .

In the drawing, the measuring device 9 is mounted on the side of the airbag cover 3 opposite the source 7 for electromagnetic radiation. The measuring device 9 can also be located on the same side as the source 7 for electromagnetic radiation. In this case, the outgoing residual radiation 28 is the reflected part. Measuring devices 9 can also be positioned on both sides of the plastic part 3 . An analysis beam 8 emanates from the source 7 for electromagnetic radiation. This analysis beam 8 is directed onto the surface 12 of the airbag cover 3 . The analysis beam can be perpendicular to the surface 12 or at an angle other than 90 °. The measured residual radiation 28 emanating from the plastic part 3 is then the transmitted and reflected part of the electromagnetic analysis beam 8 . This measurement can take place simultaneously, in the sense of a single analysis beam 8 . The measuring devices 9 are then positioned according to the angle of incidence, which is equal to the angle of reflection = angle of reflection, and the approximately known refractive behavior. The exact value for the refractive index then results from the area in which the refracted and transmitted residual beam 28 is picked up on a light-sensitive chip, which in such a case is part of the measuring device 9 . The term pick-up area refers to the fact that the refraction behavior is wavelength-dependent. The electromagnetic analysis radiation 8 used can be multi-colored. As a result, the refraction results in a, albeit slight, spectral fanning out of the refracted transmitted residual beam 28 . With a correspondingly finely structured spectrally sensitive chip, however, this fanning out can be resolved and evaluated. It can be ensured that the wavelengths in the analysis beam 8 are selected in accordance with a strong fanning out. The fanning out by the refraction can also be reinforced by a corresponding angle of incidence. The angle of incidence is, however, limited by the absorption rate of the material, since if the penetration path is too long, residual radiation 28 which cannot be evaluated sufficiently is transmitted. On the other hand, the measurement can also take place at a time interval. Two analysis beams 8 are then used in this method. However, one of them should be emitted at a non-rectangular angle to the surface 12 towards the plastic part 3 .

The airbag cover 3 is illuminated and illuminated by the electromagnetic analysis beam 8 , which is emitted by the source 7 for electromagnetic radiation in the direction of the surface 12 of the airbag seal 3 . The measuring device 9 measures the transmitted electromagnetic residual radiation 28 . The data obtained from the measuring device 9 are sent via the data bus 11 to a data processing system 5 . The measured values are compared in the data processing system 5 with stored measured values in order to determine the material compositions of the airbag seal 3 . Since there is no information about the material thickness 22 of the airbag cover 3, the measured values are mapped onto the comparison value sets, which include the possible material thicknesses 22 . These measured value sets are then processed further using information technology using fuzzy logic. The fuzzy logic algorithms then provide the material composition by comparing the measured value sets with comparison value ranges. The comparison value ranges come from laboratory tests. In the laboratory tests, the material-determining comparative values were determined for different material compositions and thicknesses. The comparison values were then stored in comparison value sets, the comparison value ranges. These comparison value sets link a value from the quantity with different material thicknesses and material compositions, for which the same or interpolated the same value was determined. The control data for the radiation source 4 are then determined from the material composition of the airbag cover 3 .

The evaluation of the incoming information should be in real time Program environment. This program environment can be an operating system be a so-called real-time operating system or real-time operating system. It However, there are also so-called embedded systems  Real-time measured value acquisition and processing without the full value Operating systems, according to colloquial definition, are in operation.

This has the advantage that the receipt of information is ensured. That means that the incoming information within a fixed unit of time from the measuring unit in reception and fed to the data processing program become. This defines the period within which no new ones of the same type are created Information may be generated in order not to overwrite the already measured. By determining the data entry time and knowing the maximum Computing time, the minimum default time value can be set after the information received is a response in the form of tax data.

The data processing time can be determined by the complexity of the program structure Size of the available memory, as well as the number of executing the program Reduce processors. This has the advantage that the processing speed can be increased as needed. As an alternative, there is the Performance increase that can be gained through parallel processing in, at Need to put more detailed investigations. This would have the advantage that the Tear properties could be coordinated even better.

The memory in the data processing system, in the form of semiconductor components correspondingly faster response time, should the amount of data determined in the laboratory be appropriate. This then has the advantage that the comparison value ranges for a rapid data processing are included as completely as possible in the memory. Thereby the problem of time-consuming information access to external storage media such as Hard drives or CD-ROM drives or streamers are eliminated. The one in memory lying information can be compared directly with each other in registration.

The task of evaluating measured values can also be parallelized. Parallelisable means that an incoming information package for data processing on multiple processors is divided.

Another possible parallelization is that each incoming information package is one Allocate free processor for processing, thereby the Increase information processing speed.  

On the other hand, the incoming information packages can each one of the Amount of information adapted processor clusters are passed. The The scope of information is in the definition and thus in the establishment of the cluster already firm. All of this shortens the response time to output the tax data.

The radiation source 4 is located in FIG. 1 above the recess 24 being processed . The data processing system 5 transmits the control data for regulating the beam 6 to the radiation source 4 via the control line 13 . The radiation source 4 can be controllable as far as the power to be output is concerned. The radiation source 4 provides a beam 6 of an electromagnetic nature which is able to introduce a depression 2 into the airbag cover 3 . The mechanical properties of the surrounding material are not changed beyond the absolutely necessary minimum. A pulsating beam 6 further reduces the energy diffusion into the environment. This reduces the possible structural changes due to energy input to almost zero. The invention avoids the problem of the melting effects occurring due to the application of heat, as well as molecular changes in the structure caused by further heat, since the laser is only used selectively. It is also advantageous that the laser beam 6 is used only for a very short time because of its high energy concentration. The desired recess is obtained after just a short use of the laser. Due to the shortness of this use, the excitation of the surrounding material is minimal. In the preferred embodiment according to the invention, the radiation source 4 is a laser. However, it is conceivable that with a suitable adjustment a burl or an electron beam can also be used. Furthermore, it is conceivable that, in addition to the radiation source shown, 4 further radiation sources are assigned to a measuring unit for the purpose of deepening. This has the advantage that a certain amount of parallel processing can take place. This parallel processing can be carried out if sufficient material homogeneity can be assumed or is given over the area covered by the additional radiation sources.

The laser beam 6 burns a depression 2 in the material of the airbag cover 3 . An intensity sensor 10 is located on the side opposite the point of incidence of the laser beam 6 in the beam direction. This measures the laser beam residue 16 transmitted through the remaining wall 15 . The measured intensity value of the transmitted laser beam 16 is transmitted to the data processing system 5 via the data bus 11 . There the intensity value is compared with the control signal, which is predetermined on the basis of the material composition. The change in intensity can also be evaluated over the duration of the laser use. This has the advantage of obtaining a further fine adjustment with regard to the material composition and the material thickness 22 . The comparison evaluation then determines whether the radiation source 4 is switched off. Whether it is switched off depends on how far the recess 24 has been made in the airbag cover 3 . It is a question of whether the remaining wall thickness 15 is correspondingly thin or whether the remaining wall thickness 15 is still so large that the laser beam 6 must continue to remove material.

A further embodiment of the invention can be seen in FIG . It differs from FIG. 1 in that there is no separate measuring device. The material composition is determined here by measuring the transmitted laser beam 16 . The measured value is evaluated in a data processing system 5 and the control data are transmitted as described in FIG. 1.

A further possible embodiment of the invention is shown in FIG. 5. A source 7 for electromagnetic radiation is located above the airbag cover 3 . In this case, this source 7 is a laser scanner which emits differently colored laser light through the airbag cover 3 . A measuring device 9 is located on the opposite side of the airbag cover 3 in the beam direction. This is a scanner sensor that is sensitive to the reception of the different colored laser beams. The multicolored laser beams emitted by the source 7 for electromagnetic radiation can be emitted either simultaneously or at different times.

Accordingly, the measuring device 9 measures the incoming radiation 28 . The measurement data of the measuring device 9 are transmitted via the data bus 11 to the computer 40 , which in combination with the control center 41 corresponds to the computer in FIGS. 1 + 2. The computer 40 receives the data as it is shown graphically in image 29 . Figure 29 shows the measurement data graphically in an XY coordinate system. The wavelengths are plotted on the X axis and the associated intensity values on the Y axis. This results in a material-specific representation of the wavelengths used in the XY coordinate system according to their transmitted intensity. The intensity distribution of the transmitted laser light depends on the wavelength used and the absorption capacity of the airbag cover 3 according to the material composition. The intensity value of the wavelength used is transmitted from the radiation source 4 , here a laser. This intensity value is compared with the intensity value for the wavelength of the light emitted by the source 7 measured by the measuring device 9 , the intensity of the radiation emitted by the source 7 also being taken into account. The absorption behavior for a material thickness X can then be determined from these data. However, the exact material thickness X is not known. This results in a range of values from transmission properties to material thickness or transmitted intensity to material thickness. The material composition can be determined from the intensity distribution of the wavelength used and the transmitted light measured on the measuring device 9 within the limits of the unknown material thickness. The determination of the material composition takes advantage of the fact that the absorption pattern is individually characteristic for each material composition. This gives a material-specific pattern based on the known radiation power of the analysis beam and the measured transmission intensity distribution according to the spectrum used. This pattern can be used in a correspondingly structured database with correspondingly comprehensive formulations for the fairly exact determination of the composition of the airbag cover 3 . This calculation of the parameters, which leads to the determination of the material composition, is sketched in Figure 29 . It is designed as a two-dimensional coordinate system with an X axis and an intensity curve plotted above it. The curve reflects the decrease in intensity with increasing material thickness X. This curve can then be used to calculate the material thickness X at which an intensity drop to 50% has been reached. This material thickness, which causes the intensity to weaken to 50%, is then called the half-value thickness. This half-value thickness can now be determined for each of the wavelengths used. This then results in a number tuple comprising the number of wavelengths. However, since the exact material thickness X is not known, a diagram according to the form in Figure 30 is not so easily applicable. Therefore, one proceeds to a diagram based on the h _1/2 I ₀ I model, as shown in Figure 31 . The course of the intensity distribution of the wavelengths used for the analysis is mapped onto comparison curves from laboratory tests for different material compositions and thicknesses. However, this mapping takes place with blurring. Both the measured values and the comparison value sets are subjected to some blurring. This impingement of blur also makes it easy to handle simple inaccuracies in large-scale application. Due to the blurring, there are different matches for the individual wavelengths. These matches relate to different material compositions. In spite of this, it gradually crystallizes through cross-matching processes, see also Figure 32 , a common match for a certain material composition. If this material composition is not exactly specified by laboratory measurements, it can be interpolated from the already determined in the laboratory by cross-references and known chemical laws using fuzzy logic algorithms. This interpolation or the possibly exactly determined composition is then the basis for determining the material thickness 22 .

The absorption behavior known from the material composition is used for this. Since the radiation power is known, as is the intensity of the transmitted light, the material thickness can be calculated using a simple Euler function. The control data for the laser control are then determined from the material thickness 22 and the mechanical properties of the airbag cover 3 determined with the material composition.

These results are determined in a so-called fuzzy control loop, as outlined in Figure 32 . This fuzzy control loop consists of algorithms that are adapted to this and are designed by their conception to use and evaluate verbally formulated knowledge to describe a system behavior. In technical terms, the term "fuzzy" usually means "out of focus". In order to be able to deal with the fuzzy logic, problems or their value representatives are presented in fuzzy sets, the fuzzy sets. The individual fuzzy sets are then linked with the evaluation of knowledge-based if-then rules. The combination of a rule base created in this way with the mathematical formulation of unsharp quantities enables human decision elements with unsharp language elements in conjunction with linguistically formulated knowledge to be machine-quantified and thus processable (see also Altrock VC: Fuzzi-Logic, R. Ouldenburg Verlag, Munich , 1993). The calculation by means of this fuzzy logic takes place in a master computer 40 which is provided with an interface in order to address a control center 41 or to receive feedback pulses from this control center 41 . The control center 41 converts the data determined by the master computer 40 into control pulses which are forwarded to the radiation source 4 via the control line 13 . Several different control methods for the radiation source 4 are conceivable here. One of them is that the radiation source 4 receives both time and intensity information. This then means that for a certain period of time, which is specified by the control center 41 , and at a specific laser power, which is also specified by the control center 41 , the laser beam 6 onto the airbag cover 3 for introducing the recess 24 being processed up to an insertion depth 23 acts. The remaining wall thickness 15 can vary from instrument panel to instrument panel or from recess 2 to recess 2 , depending on the local material composition.

The second activation is limited to time information that is transmitted from the control center 41 to the radiation source 4 . For the sake of simplicity, it is assumed that the radiation source 4 operates with a fixed intensity.

The radiation source can also be power-controlled.

As a result, only a time value is required to make a recess 24 in the airbag cover 3 . It is therefore clear that parameters are determined by recording the measured values of laser power, feed, transmission and sensor message that occur during work. These parameters are used to calculate the current processing status on the basis of an h _1/2 I ₀ I model. The algorithm of the fuzzy controller compares the current processing status with the target value, calculates any necessary corrections to the processing parameters and transfers them to the control center 41 via the control computer interface.

REFERENCE SIGN LIST

1

investment

2nd

deepening

3rd

Plastic part, airbag cover

4th

Radiation source

5

Data processing system

6

laser beam

7

Source of electromagnetic radiation

8th

electromagnetic radiation

9

Measuring device

10th

Laser beam sensor

11

Data bus

12th

Surface of

3rd

13

Control line

14

Control line

15

Residual wall thickness

16

transmitted laser beam

17th

dashboard

18th

Airbag

19th

Detonator

20th

Passenger compartment

22

Material thickness

23

Insertion depth

24th

Work in progress

25th

planned deepening

28

Residual radiation

29

image

30th

image

31

image

32

image

40

computer

41

Tax control center

42

Data transmission

43

Data transmission

44

Windshield

Claims (15)

1. A method for introducing depressions ( 2 ) in plastic parts ( 3 ) by means of a controllable radiation source ( 4 ), wherein electromagnetic rays ( 8 ) are directed onto the surface ( 12 ) of the plastic part ( 3 ), and one of the composition of the Measured variable dependent on plastic material, which is a component of the outgoing electromagnetic radiation ( 28 ), is detected and converted into a control signal which is used to control the irradiation power of the controllable radiation source ( 4 ). 2. The method according to claim 1, wherein the incoming electromagnetic radiation ( 8 ) is directed to a location on the surface ( 12 ) at which a depression ( 2 ) corresponding to the measured value is subsequently introduced. 3. The method according to claim 1 or 2, wherein the respective measured value between stored measured values interpolated and the associated control signal is also interpolated. 4. The method according to claim 3, wherein the stored measured values are stored in terms of software or hardware in an electronic data processing system ( 5 ). 5. The method according to any one of claims 1 to 4, wherein the measured variable in one real-time capable IT system using so-called fuzzy logic into one Control signal is converted. 6. The method according to any one of claims 1 to 5, wherein the controllable radiation source ( 4 ) and the source of electromagnetic radiation ( 7 ) are different from each other. 7. The method according to any one of claims 1 to 5, wherein the controllable radiation source ( 4 ) and the source of electromagnetic radiation ( 7 ) are identical and are operated in succession. 8. The method according to any one of claims 1 to 7, wherein the operating intervals become shorter with increasing depth of entry ( 23 ). 9. The method according to any one of claims 1 to 8, wherein the depression ( 2 ) causing beam ( 6 ) acts as a measuring beam ( 8 ). 10. The method according to any one of claims 1 to 9, characterized in that the ratio of the radiated power of the electromagnetic radiation ( 8 ) to the reflected power is used as the measured variable. 11. The method according to any one of claims 1 to 9, characterized in that the ratio of the radiated power of the electromagnetic radiation ( 8 ) to the transmitted power is used as the measured variable. 12. Device for performing the method according to one of claims 1 to 11, with

• 1. 12.1 a source of electromagnetic radiation ( 4 )
• 2. 12.2 an analysis device for determining the quantity dependent on the plastic material by means of the electromagnetic radiation ( 28 ) which emanates from the surface ( 12 ) of the plastic part ( 3 )
• 3. 12.3 a device for evaluating the measured variable and determining control data for
• 4. 12.4 a controllable radiation source ( 4 ) for introducing the depression ( 2 ), and
• 5. 12.5 a measuring device ( 10 ) to control the insertion of the recess ( 2 ).

13. The apparatus according to claim 12, characterized in that a multi-spectrum lamp with time-controlled filters is used as the source of electromagnetic radiation ( 7 ) and an intensity-sensitive photosensor as the analysis device ( 9 ). 14. The apparatus according to claim 12, characterized in that a monochromatic time-controlled light source is used as the source for the electromagnetic radiation ( 7 ). 15. The apparatus according to claim 12, characterized in that the device for evaluating the measured variable and determining the control data is a data processing system ( 5 ), that the data processing system ( 5 ) performs the data processing in real time, and that the program that performs the data processing on the so-called fuzzy logic.