AU2005200560B2 - Process and apparatus for weakening an automotive trim piece for an airbag deployment opening - Google Patents

Description

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT Applicant: TIP ENGINEERING GROUP, INC.

Invention Title: PROCESS AND APPARATUS FOR WEAKENING AN AUTOMOTIVE TRIM PIECE FOR AN AIRBAG DEPLOYMENT OPENING The following statement is a full description of this invention, including the best method of performing it known to me/us: 1A PROCESS AND APPARATUS FOR WEAKENING AN AUTOMOTIVE TRIM PIECE FOR AN AIRBAG DEPLOYMENT OPENING Cross Reference to Related Applications This application is divided from earlier application number 2001247477 dated 16 March 2001.

Background of the Invention This invention concerns forming lines of weakness in portions of automotive trim pieces overlying airbag safety devices, in order to allow one or more airbag deployment doors to be created when an airbag is inflated.

Airbag safety systems are widely used in automotive vehicles and generally comprise an inflatable cushion, referred to as an "airbag", stored folded in a receptacle and then rapidly inflated when a collision of the vehicle is detected by sensors.

The folded airbag is typically mounted behind an automotive interior trim piece such as an instrument panel or a steering wheel cover. One or more airbag deployment doors are forced open when the airbag is inflated to allow deployment of the airbag through the opening created by the deployment door movement.

During the last few years, airbag deployment doors that are integrated into the trim piece overlying the airbag receptacle have gained wide acceptance. As described in U.S. Patents 5,082,310 and 5,744,776, these integrated doors employ a seamless or invisible construction whereby the deployment doors or doors, although part of the trim piece, are not separately delineated and/or visible from the passenger side of the trim piece.

For such integrated deployment doors to open during airbag deployment necessitates weakening portions of the trim piece in order to allow trim piece sections to H:\nicolab\keep\Speci\P55899 div.doc 9/02/05 2 break free and hinge open. Weakening of the trim piece is carried out by creative lines of weakness comprised of scored lines formed by removing material from the trim piece from the back surface along a predetermined deployment door pattern. A critical component of this process is the amount of the trim piece material removed and/or remaining after cutting the score line. Accurate control of this process is critical to reliably producing proper airbag deployments.

A widely used method for determining the extent of material removal during scoring involves the use of triangulation type sensors as described in U.S. Patent 5,883,356. These sensors, however, due to their triangulation operating principle, are limited in their ability to reach the bottom of the scoring produced by the cutting device. This is particularly so for narrow, deep penetrations which may be imparted by cutting devices such as lasers and cutting knives. Furthermore, due to their offset mounting, these sensors are not well suited to measure the varying penetration depth that occurs during scoring at a specific location. This is especially true if the scoring penetration is in the form of partial perforations or slots. As such, the process does not lend itself to scoring the trim piece in an adaptive control mode, where both depth sensing and scoring are in registry with each other to impinge the same point on the trim piece, during the progression of scoring of the trim piece.

Accordingly it is an object of this invention to provide a process and apparatus for scoring trim components overlying airbag installations in a manner that provides accurate adaptive process control, signal-pass processing, improved airbag door deployment, and lower manufacturing costs.

H:\nicolab\keep\Speci\P55899 div.doc 9/02/05 0 Summary of the Invention ci ;According to one aspect of the invention there is provided a process for weakening an automotive trim piece covering an airbag installation, said airbag installation including an airbag adapted to be inflated and deployed upon detection of a collision, said weakening enabling V formation of an airbag deployment door opening therein by pressure developed by deployment of said airbag, said trim V) 10 piece having at least one layer, comprising: O partially cutting into a surface of the trim piece by directing a cutting beam from a cutting beam source onto said surface and moving said trim piece relative to said cutting beam in a predetermined weakening pattern; generating first and second sensor beams from a first sensor and a second sensor respectively and directing said first and second sensor beams towards respective opposite sides of said trim piece at each trim piece location being cut by said cutting beam, said first sensor beam directed towards the same side of said trim piece as said cutting beam; combining said first sensor beam with said cutting beam so that combined respective segments are collinear with each other when impinging said trim piece surface so as to be directed at the same point along said weakening pattern; monitoring the extent of cutting produced by said cutting beam, said monitoring including analysing said first sensor beam and a return beam reflected from said surface after impingement by said first sensor beam by a conoscopic holography process; and controlling the remaining thickness of said trim piece at each point along said predetermined weakening pattern by controlling said cutting in correspondence with feedback signals generated from said first and second sensors.

Hi\melindaf\keep\Spee l'\P5599.doc 6/os08/05 3a 0 0 According to another aspect of the invention there is 1 provided a process for weakening an automotive trim piece ;covering an airbag installation, said airbag installation including an airbag adapted to be inflated and deployed upon detection of a collision, said weakening enabling formation of an airbag deployment door opening by said trim piece having at least one layer, comprising the steps

IN

oof: opartially cutting into a surface of said trim piece by directing a cutting beam at said inside surface from a o cutting beam source, and relatively moving said trim piece and said cutting beam in a predetermined pattern after loading said trim piece onto a fixture where a surface of said trim piece is in intimate contact with a surface of said fixture; directing a sensor beam produced from a sensor towards the trim piece location being cut by said cutting beam, said sensor beam located on the same side of said trim piece as said cutting beam; combining said sensor beam and said cutting beam so as to have collinear segments thereof impinging said surface so that both beams impinge the same point on said trim piece; monitoring the extent of cutting effecting by said cutting beam, said monitoring including analysing said sensor beam and a beam reflected back from said surface after impingement by said sensor beam by a conoscopic holography process; and controlling the remaining thickness of said trim piece at each point along said predetermined pattern in accordance with feedback signals generated from said sensor beam.

According to a further aspect of the invention there is provided an apparatus for weakening an automotive trim piece covering an airbag installation, said airbag installation including an airbag adapted to be inflated Ki\melindaf\keep\Speci's\P55899.doc 26/08/05s 3b o and deployed upon detection of a collision, said weakening enabling formation of an airbag deployment door opening by ;pressure developed by deployment of said airbag, said trim piece having at least one layer, comprising: a source for a cutting beam able to cut into a surface on one side of said trim piece, said cutting beam 0 directed at said surface of said trim piece; a motion actuator imparting relative motion between said cutting beam and said trim piece in a predetermined S 10 pattern; 0 o sensor means for monitoring the remaining material thickness of said trim piece, said sensor means including a first sensor beam source and a second sensor beam source, for generating a first and second sensor beam respectively, said first and second sensor beams directed to respective opposite sides of the said trim piece and towards a point on said trim piece being cut by said cutting beam; said first sensor beam located on the same side of trim piece as said cutting beam, said sensor means analysing said first sensor beam and a beam reflected back from said trim piece surface after impingement by said first sensor beam by a conoscopic holography process; a beam combiner combining said cutting beam and said first sensor beam to be in a collinear relationship, said collinear beams continuously directed at the same point on said trim piece; and control means adjusting the cutting effect of said cutting beam, responsive to feedback signals generated by said sensor means to leave a predetermined thickness of trim piece material remaining along said predetermined pattern.

According to another aspect of the invention there is provided an apparatus for weakening an automotive trim piece covering an airbag installation, said airbag installation including an airbag adapted to be inflated H,\melindaf\keep\Speci' e\P55699.doc 26/1D08/05O 3c 0 0 and deployed upon detection of a collision, said weakening oenabling formation of an airbag deployment door opening by ;pressure developed by deploying of said airbag, said trim piece having at least one layer, comprising: a fixture for holding a trim piece; a source for a cutting beam able to cut into said Strim piece, said cutting beam directed at one side of a S trim piece held in said fixture; Sa motion actuator imparting relative motion between V) 10 said cutting beam and said trim piece along a opredetermined pattern; sensor means for monitoring the cutting effected on a said trim piece by said cutting beam, said sensor means including a sensor beam source generating a sensor beam, said sensor beam directed at the same side of said trim piece as said cutting beam and to each trim piece point being cut by said cutting beam by control means, said sensor means determining the extent of cutting produced by said cutting beam by a conoscopic holography process; a combining device combining segments of said cutting beam and said sensor beam downstream from their respective sources to be collinear with each other, said collinear beam segments both directed at the same point on said trim piece by control means; and said control means adjusting the cutting effected by said cutting beam responsive to feedback signals generated by said sensor means so as to leave a predetermined thickness of trim piece material remaining along said predetermined pattern.

Description of the Drawings Figure 1 is a diagrammatic view of one form of the apparatus according to the invention including two sensors; Figure 2, 2A and 2B are fragmentary enlarged views of several alternative designs of the beam combining device H :\mel indaf\keep\SpeCe'uw\P55199.doc 26/01/05 4 o a o incorporated in the apparatus shown in Figure 1; Figure 3 is an automotive instrument panel with an Sintegrated airbag deployment door formed by in a U pattern scoring carried out by the apparatus and process of the C 5 present invention; Figures 4 through 6 are cross sectional views of Ssample monolayer and multilayer trim piece constructions Son which various types of trim piece weakening scorings o have been made; Vn 10 Figure 7 is a diagrammatic view of one form of the o apparatus according to the invention incorporating only a single sensor; and Figure 8 is a diagrammatic view of a second form of the apparatus according to the invention incorporating only a single sensor.

H.\melnda\keep\Speci '\P55899.doc 26/08/05 SDetailed Description In the following detailed description, certain specific terminology will be employed for the sake of clarity and particular embodiments described, but it is to be Sunderstood that the same is not intended to be limiting and should not be so construed inasmuch as the invention is capable of taking many forms and variations within the scope of the appended claims.

This invention describes an improved process and apparatus for forming lines of weakness in an automotive trim piece for an airbag door installation in a way that C improves the accuracy of the process, the trim piece quality, the airbag deployment performance, and, also, reduces trim piece production costs. The process will be described with respect to an instrument panel airbag door installation, but it is also applicable to other 12 automotive and non-automotive installations, with or without an airbag. Typical airbag 13 installations include driver side airbags, front passenger airbags, side impact airbags, 14 headliner airbags, knee airbags, and rear passenger airbags. The process will also be described in terms of a laser beam, but is also applicable to other cutting beams as described 16 below.

7 Figure 1 shows a first embodiment of a trim piece scoring apparatus 18 according to the invention. This includes a cutting beam source 12 which generates a cutting 19 beam such as a laser beam which is used to carry out controlled scoring of a surface 14 on one side of an instrument panel trim piece 16 that would overlie an airbag installation when 21 installed.

22 The trim piece 16 is positioned on a fixture 18. A first sensor 20 is provided 23 to determine the depth of scoring produced by the laser cutting beam onto the surface 14 of 24 the trim piece 16 to weaken the same. The first sensor 20 and the cutting beam generator 12 t -are connected to a beam combining device 22. The beam combining device 22 (shown in S detail in Figure 2) is designed to combine separately generated sensing beam or beams A emanating from the first sensor 20 and the laser cutting beam B from source 12 so as to be in S a collinear relationship and to direct the combined segments of the sensor A and cutting beam B so as to impinge the same precise spot on the trim piece surface 14. This beam IND combining device 22 will also redirect any reflected returned beam or beams required for sensor operation from the trim piece surface 14 back to the first sensor 20 as necessary in carrying out the process.

The trim piece 16 is moved relative to the cutting laser beam source 12, as well as the first sensor 20 and the beam combining device 22 via a motion actuator 24 to cause tracing of a particular scoring pattern and to achieve a precisely controlled rate of 12 scoring. The motion actuator 24 can directly move the trim piece 16 itself or move an 13 optional fixture 18 onto which the trim piece 16 is mounted. Alternatively, the motion 14 actuator 24 could be used to move the laser beam source 12 and the first sensor 20 relative to the trim piece 16.

16 A second sensor 26 may be located on the side of the trim piece 16 opposite 7 the first sensor 20, a second sensor beam emanating therefrom, directed at the outer surface 18 28 of the trim piece 16 and aligned opposite the same trim piece point as is the laser cutting 19 beam and the first sensor beam or beams are directed in order to control the scoring so as to produce a programmed thickness of material remaining after scoring. This is done by 21 combining signals generated by both sensors 20, 26 to create a feedback signal corresponding 22 to the thickness of the remaining material.

23 The apparatus 10 is operated via one or more industrial controllers 30 that 24 control the scoring effected by the laser -and/or the movement of the motion actuator based on a particular program and feedback signals provided by the sensor 20, 26.

26 Lasers are particularly desirable for carrying out this type of scoring processes and they can be of the carbon dioxide, excimer,. solid state, argon gas, or diode type.

However, based on the primary trim piece -materials utilized (polymers, fabrics, wood, leather), the carbon dioxide laser is likely to be the most preferable in terms of operability, C efficiency and cost. The laser can be operated either continuously or in a pulsed mode.

Different type of sensors can be utilized to measure the extent of material IC removed or remaining during scoring of the trim piece. For the first sensor 20, connected to 0 the beam combining device 22, a preferred type is a closed loop device that sends, and i: .ceives a specific beam of electromagnetic radiation in order to determine the depth of scoring effected by the laser. The Conoprobe sensors offered by Optimet and based on the technique of conoscopic holography, is one such sensor commercially. available. In this type of sensor, an emitted laser beam and reflected return beams of visible light have segments 12 also traveling in a collinear relationship with each other and the laser beam. Another type of 13 sensor that could be utilized is one that detects reflected light beams such as a high speed 14 CCD camera. In this application, the reflected beam will be reflected from the trim piece surface being scored by the cutting beam.

16 For the second sensor 26 aimed at the outside surface of the trim piece, which 7 is generally smooth and accessible, there are more numerous options including, infrared, 18 laser, ultrasonic, conoscopic, CCD camera, proximity and contact type sensors.

19 The signal spot size of the sensor beam selected can vary significantly.

Generally the smaller the spot size the better. For the first sensor, the preferred size would 21 not exceed the size of the scoring produced on the trim piece by the cutting laser beam. For 22 the second sensor, if surface finish variations, so called grain, are significant, its spot size 23 should preferably not exceed 300 microns.

24 There are numerous ways for combining the separately originated cutting laser beam B and sensor beam A to create collinear segments thereof. Figure 2 shows the inner details of the beam combining device 22 which combines the separate laser beam A and the first sensor beam B to create collinear segments which impinge the trim piece surface 14.

The beam combining device 22 includes a reflector 32 having coatings causing reflection of light of the wavelength of the sensor beam A from its inclined surface while allowing the S cutting laser beam B to be transmitted.

SSuch coated selective reflectors are commercially available. This of course 0 requires that tile laser and sensor beams be of differentwavelengths.

A side entrance tube 29 directed at the reflector 32 is connected to the first sensor 20. The main tube 31 mounts the reflector 32, main tube 31 having an end opening 33 directed at the trim piece 16.

12 The segment of the sensor beam A reflected from the reflector 32 is caused to 13 be collinear, aligned and coextensive with the segment of the laser beam B past the 14 reflector 32, with both collinear segments then impinging the surface 14 at the same precise point.

16 Figure 2A shows a second form of a beam combining device 22A having an 7 inclined reflector 32A having coatings causing reflection of a beam having the wavelength of 18 the cutting laser beam B, while allowing transmission of the beam having wavelengths of the 19 sensor beam A to be transmitted therethrough to reverse the relationship shown in Figure 2.

Figure 2B is a simplified diagrammatic view of another form of the beam 21 combining device 22B combining the cutting laser beam B and the first sensor beam A to 22 produce collinear downstream segments thereof. This embodiment includes a simple mirror 23 reflector 36 having a through hole 34. The hole 34 is small in diameter relative to the 24 diameter of the cutting laser beam B in order to minimize or eliminate the effect that the presence of the hole 34 may have on reflecting the cutting laser beam B from the mirror are wavelength-selective such as those shown in Figures 2 and 2A in order to combine S segments of the beams into a collinear relationship. In this particular arrangement, the first sensor 20 could be a CCD camera receiving beams reflected from the trim piece surface being scored by the laser beam.

The trim piece can be any of many automotive parts including instrument NO panels and/or their components (skins, substrates, foams, scrims, etc.), driver side airbag covers, door panels, seat covers, headliners, bumpers and seat belts. The scoring can be applied on either side of the trim piece but is preferably applied from the inside so that is I substantially invisible from the outside surface facing the passenger. As shown in Figure 3, the scoring does not penetrate the outer surface 28 of the trim piece 16 shown as an instrument panel and would be essentially invisible to the passenger. Different materials 12 could be utilized in a trim piece including metals, polymers (TPUs, TPOs, PVC, TPEs, etc.), 13 leather, fabrics, wood and wood composites. As shown in Figures 4 through 6, the trim piece 14 16, 16A, 16B may consist of one or more layers of similar or dissimilar materials. In multilayer constructions, the scorings 40, 40A, 40B could be applied to any one layer or any 16 combination thereof as shown.

7 Manufacturing of the trim piece can be done in several ways using different 18 materials. Many of these materials can be formed in a solid state or in a cellular state.

19 Polymeric trim pieces can be formed by processes such as extrusion, injection molding, low pressure insert molding, blow molding, casting, thermoforming, lamination and foaming.

21 The scoring applied can be in any shape, including a U, H, I, T, X, W, S and Y 22 pattern, required to form an opening for the airbag to deploy. The opening could include one 23 or more door panels. The scoring can be either continuous or discontinuous including 24 grooves, blind holes and dashes. Furthermore, the cut orientation can be straight or offset.

9 -For successful and consistent.airbag deployments, the degree of precision of cutting is

O

0 particularly important to ensure that the amount of material remaining along the predetermined pattern is as intended. The penetration or depth of scoring, for an invisible airbag door application, can be up to about 95% of the trim piece thickness.

In order to apply the complete scoring pattern, the trim piece is preferably t moved relative to the laser beam and/or the sensors. The relative motion can be applied by a 0 number of motion actuators including robots and X-Y tables. During cutting, the sensor O thickness data can al c be used to control the movement of the motion device in order to apply the scoring along the predetermined pattern. The trim piece may be held directly by the motion device or be attached to a holding fixture held by the motion device. The holding fixture may be shaped to match the shape of the trim piece and/or be designed to register 12 specific surface features of the trim piece. Vacuum or clamps could also be applied to the 13 holding fixture to hold the trim piece surface in better contact with the fixture 18. The fixture 14 18 can be designed to allow the second sensor 28 to have physical and/or optical access to the surface 26 of the trim piece transparent fixture wall, opening in fixture wall, etc.).

16 The process controller 30 is designed to control the operation of the laser 7 and/or motion actuator based on the feedback signals provided by the two sensors 20, 26 18 which, from opposites sides or surfaces of the trim piece 16, monitor the location being 19 scored. The two sensors 20, 26 working in tandem determine the remaining thickness of the trim piece 16 at any point they are directed to. During laser scoring at a given point, the two 21 sensors 20, 26 provide signals from which a measurement of the material thickness 22 remaining after the scoring can be derived by the control device 30. Based on this real-time 23 thickness determination, the control device 30 controls the operation of the cutting beamn 24 source 12 to effect only the desired extent of material removal intended for any given point tt on the trim piece 16. The remaining thickness data can also be used to control the motion actuator 24 to move the trim piece to the next desired location along the predetermined scoring pattern.

Due to the collinearity of the impinging segments of the first sensor beam and the cutting beam, several advantages are realized that could not be attained by any of the 0 existing processes. Since the first sensor beam and the laser beam are always impinging on the same point on the trim piece, the process becomes insensitive to a large number of key ,1 ttC)a variaf neuding-he-angte-ofoeu e-depth-of-thepenetration-,-the-trim-piecethickness, the configuration of the weakening pattern and, to a large extent, the speed of cutting. Also, the combination of the two sensors provides for a direct remaining thickness measurement, superior scoring precision and excellent part to part repeatability. In addition, 12 the process enables the user to overcome variations in trim piece thickness, material 13 properties such as density, color, voids and surface grain. These and other benefits are 14 obtained while operating with rapid adaptive control in a single-pass mode.

A second embodiment of the apparatus 44 according to the invention is shown 16 in Figure 7 where the outer surface 42 of the trim piece 16 is in intimate contact with the 7 inner fixture wall 46. In this arrangement, the distance between the first sensor 48 and the 18 fixture inner wall 46, along the predetermined scoring pattern, can be measured prior to .19 starting the scoring operation. If this distance can be maintained constant from pass to pass, then the second outside sensor would not be necessary while still running the process in a 21 single-pass, adaptive control mode.

22 Figure 8 shows another embodiment of the apparatus 50 where the first sensor 23 52 is mounted immediately alongside the cutting beam source 12 so that both beams A, B are 24 substantially collinear with each other to approximate the effect of using the beam combining 11 1 device 22 described.

O 2 The laser cutting beam may also function as the sensor. This arrangement 3 also maintains the collinear configuration as the sensing signals and the laser beam are S4 generated by the same laser. Under this approach, the laser beam characteristics and control would be manipulated to conduct sensing measurements during or between cutting intervals 6 sensing after a preset number of cutting pulses).

S7 C In the claims which follow and in the preceding description of the invention, except where the context Srequires otherwise due to express language or necessary c-i implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.

Claims (19)

1. A process for weakening an automotive trim piece C covering an airbag installation, said airbag installation including an airbag adapted to be inflated and deployed upon detection of a collision, said weakening enabling formation of an airbag deployment door opening therein by pressure developed by deployment of said airbag, said trim piece having at least one layer, comprising: V 10 partially cutting into a surface of the trim piece by o directing a cutting beam from a cutting beam source onto said surface and moving said trim piece relative to said cutting beam in a predetermined weakening pattern; generating first and second sensor beams from a first sensor and a second sensor respectively and directing said first and second sensor beams towards respective opposite sides of said trim piece at each trim piece location being cut by said cutting beam, said first sensor beam directed towards the same side of said trim piece as said cutting beam; combining said first sensor beam with said cutting beam so that combined respective segments are collinear with each other when impinging said trim piece surface so as to be directed at the same point along said weakening pattern; monitoring the extent of cutting produced by said cutting beam, said monitoring including analysing said first sensor beam and a return beam reflected from said surface after impingement by said first sensor beam by a conoscopic holography process; and controlling the remaining thickness of said trim piece at each point along said predetermined weakening pattern by controlling said cutting in correspondence with feedback signals generated from said first and second sensors.

2. The process as claimed in claim 1, wherein said H:\melindaf\keep\Speci'\P55899.doc 26/08/05 14 C cutting beam is a laser.

3. The process as claimed in claim i, wherein said cutting beam source is an ultrasonic generator.

4. The process as claimed in claim i, wherein said 0 Sfeedback signals provided by said first and second sensor Sbeams together correspond to the material thickness remaining at each trim piece point being partially cut. 00 The process as claimed in claim i, wherein said trim piece is held in a fixture shaped to provide intimate contact with the outer surface of said trim piece.

6. The process as claimed in claim i, wherein said feedback signals produced from said sensor beams are used to also control the relative movement of said trim piece and said cutting beam.

7. A process for weakening an automotive trim piece covering an airbag installation, said airbag installation including an airbag adapted to be inflated and deployed upon detection of a collision, said weakening enabling formation of an airbag deployment door opening by said trim piece having at least one layer, comprising the steps of: partially cutting into a surface of said trim piece by directing a cutting beam at said inside surface from a cutting beam source, and relatively moving said trim piece and said cutting beam in a predetermined pattern after loading said trim piece onto a fixture where a surface of said trim piece is in intimate contact with a surface of said fixture; directing a sensor beam produced from a sensor towards the trim piece location being cut by said cutting beam, said sensor beam located on the same side of said trim piece as said cutting beam; H \melindaf\keep\Speci s\P55899.doc 26/0/05 combining said sensor beam and said cutting beam so ;Z as to have collinear segments thereof impinging said surface so that both beams impinge the same point on said trim piece; monitoring the extent of cutting effecting by said cutting bean, said monitoring including analysing said o sensor beam and a beam reflected back from said surface o after impingement by said sensor beam by a conoscopic holography process; and o controlling the remaining thickness of said trim piece at each point along said predetermined pattern in accordance with feedback signals generated from said sensor beam.

8. The process as claimed in claim 7, wherein said cutting beam is a laser beam.

9. The process as claimed in claim 1 or 7, wherein said sensor beam is electromagnetic radiation of a different wavelength than said cutting beam which is also electromagnetic, and in said combining step, said sensor and cutting beams are both directed at a reflector which selectively transmits one beam and reflects the other as a result of the difference in wavelengths to cause segments of said respective beams to be collinear. The process as claimed in claim 9, wherein said reflector is inclined at 450 and in said combining step one bean is directed at a front face of said reflector to be reflected and-the other beam is directed at a rear face of said reflector through which it is transmitted.

11. The process as claimed in claims 1 or 7, wherein said sensor beam is of much smaller diameter than said cutting beam, and wherein in said combining step, said cutting beam is directed at an inclined reflector surface having a H.\mrelindaf\keep\Specl s\P55999.doc 26108/05 IC) -16- 0hole formed therein much smaller than said cutting beam, to and said sensor beam is directed through Bald hole in a ;Z direction collinear to said cutting beam being reflected from said reflector.

12. The process as claimed in claims 5 or 7, wherein said intimate contact between said fixture and said trim piece o is enabled by applying vacuum.

13. An apparatus for weakening an automotive trim piece o covering an airbag installation, said airbag installation c-i including an airbag adapted to be inflated and deployed upon detection of a collision, said weakening enabling formation of an airbag deployment door opening by pressure developed by deployment of said airbag, said trim piece having at least one layer, comprising: a source for a cutting beam able to cut into a surface on one side of said trim piece, said cutting beam directed at said surface of said trim piece; a motion actuator imparting relative motion between said cutting beam and said trim piece in a predetermined pattern; sensor means for monitoring the remaining material thickness of said trim piece, said sensor means including a first sensor beam source and a second sensor beam source,, for generating a first and second sensor beam respectively, said first and second sensor beams directed to respective opposite sides of the said trim piece and towards a point on said trim piece being cut by said cutting beam; said first sensor beam located on the same side of trim piece as said cutting beam, said sensor means analysing said first sensor beam and a beam reflected back from said trim piece surface after impingement by said first sensor beam by a conoscopic holography process; a beam combiner combining said cutting beam and said first sensor beam to be in a collinear relationship, said H.\Pelindaf~keep\SpeiaG\PS5599.doc 26108/05 T 17 0 0g collinear beams continuously directed at the same point on Ssaid trim piece; and ;control means adjusting the cutting effect of said Ccutting beam, responsive to feedback signals generated by said sensor means to leave a predetermined thickness of trim piece material remaining along said predetermined 0 D pattern. 0y 14. The apparatus as claimed in claim 13, wherein said cutting beam source is a laser beam source. The apparatus as claimed in claim 13, wherein said trim piece is held in a fixture shaped to provide intimate contact with the outer surface of said trim piece.

16. An apparatus for weakening an automotive trim piece covering an airbag installation, said airbag installation including an airbag adapted to be inflated and deployed upon detection of a collision, said weakening enabling formation of an airbag deployment door opening by pressure developed by deploying of said airbag, aid trim piece having at least one layer, comprising: a fixture for holding a trim piece; a source for a cutting beam able to cut into said trim piece, said cutting beam directed at one side of a trim piece held in said fixture; a motion actuator imparting relative motion between said cutting beam and said trim piece along a predetermined pattern; sensor means for monitoring the cutting effected on a said trim piece by said cutting beam, said sensor means including a sensor beam source generating a sensor beam, said sensor beam directed at the same side of said trim piece as said cutting beam and to each trim piece point being cut by said cutting beam by control means, said sensor means determining the extent of cutting produced by said cutting beam by a conoscopic holography process; H: \melindaf\keep\Speci s\P55B99,doc 26/08/05 Ic) -18- a combining device combining segments of said cutting ;Z beam and said sensor beam downstream from their respective sources to be collinear with each other, said collinear beam segments both directed at the same point on said trim piece by control means; and INO said control means adjusting the cutting effected by o said cutting beam responsive to feedback signals generated 0 by said sensor means so as to leave a predetermined thickness of trim piece material remaining along said 0 o predetermined pattern.

17. The apparatus as claimed in claim 16, wherein said cutting beam is a laser beam.

18. The apparatus as claimed in claim 16, wherein said fixture has a cavity shaped to provide intimate contact with an outer surface of said trim piece on a side thereof opposite said one side.

19. The apparatus as claimed in claims 16 and 18, wherein said fixture includes a vacuum system to enable intimate contact of said fixture cavity with the outer surface of said trim piece. Dated-this 2 6 TH day of August 2005 TIP ENGINEERING GROUP PTY LTD By their Patent Attorneys GRIFFITH HACK Fellows Institute of Patent and Trade Mark Attorneys of Australia krmelindar\keep\Speci c\P599.doc 26/oe/os 19 at the same point on said trim piece; control means monitoring said cutting of said trim piece at each point along said predetermined pattern, and adjusting the cutting effect of said cutting beam to produce a predetermined thickness of trim piece material remaining after said cutting along said predetermined pattern.

21. The apparatus according to claim 20 wherein said cutting beam source is a laser beam source.

22. The apparatus according to claim 20 wherein said cutting beam source is a source of ultrasonic energy.

23. The apparatus according to claim 20 wherein said trim piece is held in a fixture shaped to provide intimate contact with the outer surface of said trim piece.

24. Apparatus for producing lines of weakening an automotive trim piece covering an airbag installation, said airbag installation including an airbag adapted to be inflated and deployed upon detection of a collision, said lines of weakening enabling formation of an airbag deployment door opening by pressure developed by deploying of said airbag, said trim piece having at least one layer, comprising: a source for a cutting beam able to cut into said trim piece, said cutting beam directed at one side of said trim piece; a motion actuator imparting relative motion between said cutting beam and said trim piece along a predetermined pattern; a sensor for monitoring the depth of cutting effected on said trim piece by said cutting beam, said sensor located on the same side of said trim piece as said source of said cutting beam and generating a sensing beam directed towards the trim piece point being cut by said H:\nicolab\keep\Speci\P55899 div.doc 9/02/05