Takata Ex. 1023
`IPR Petition - USP 9,043,093
`
`

`
`Advancements in coatings and texturing technology have made
`it possible. to control the appearance of these components so that
`they match the color, gloss and texture of the adjacent compo-
`nents.
`
`In the following Lest we will only discuss the deployment door or
`cover as produced in the injection molding process.
`
`Design Considerations
`
`Once the stylist has developed the desired shape of the door or
`cover, and the determination has been made to have a soft or
`
`hard surface. the design process can begin. The following are
`some of the issues that need to he addressed at that time. We
`
`should keep in mind that these issues are inter related and there-
`fore, design changes in one area may have a significant effect on
`the performance of another area of the part.
`
`I . Geometry of part shape.
`
`II. Location and design of the tear seam, (visible hidden or
`invisible).
`
`lIl. Methods of attachment of the door or cover to the
`
`deployment systern and surrounding components.
`IV. Selection of material.
`
`V. Selection of coatings to match color, gloss and texture
`of adjacent components.
`
`in the following. we will break down these steps and discuss
`how decisions are made in regard to the design direction.
`
`The major objectives that should be foremost in the mind of the
`designer when designing both driver covers and passenger side
`doors are:
`
`-
`
`-
`
`-
`
`Sirnplicity of design
`
`Structural integrity
`
`Simplicity and consistency of manufacttlre.
`
`Geometry of Part Shape
`
`This feature has a significant‘ relationship to the performance
`requirements of the design of the attaclimcnt system of the door
`or cover to the module. Parts having a shape that may tend to
`enlrap the airbag upon deployment can cause excessive loads
`being applied to the attachment features of the door. This is pri-
`marily a problem on passenger side doors when the tear of!"
`[lange design is used. Entrapment is due to the curvature of the
`top side of the instrument panel as shown in Figure 1. When
`encountering this condition a center tear scam rather than :1 tear
`off flange should he considered. The center tear seam allows the
`airbag to create its maximttin pressure at the weakest point of the
`door; that", being the tear seam. The result is that the tear seam is
`quickly opened with no entrapment of the airbag with rninimal
`force being applied. Using center tear scams allows the door to
`be designed with thinner attachment flanges and thereby, elimi-
`nation of the common problem of sink marks on the from sur-
`face of the door is achieved. In addition, since this design applies
`lcss force to the attachment flanges, the attachment system for
`securing the door to the module can be optimized for case of
`assembly. The benefits often are a reduction of. or the elimina-
`
`IBEC "94 I Automotive Body interior & Safety Systems - 85
`
`Airbag Door
`Development
`Technology
`Passenger
`And Driver
`
`Side Visible
`
`And Invisible
`
`Tear Seams
`
`James H. Zwcng
`Mayco Plastics, lnc.
`
`troduction
`
`
`
`ccordin g to the Institute for Highway Safety, when airbags and
`at belts are used together. they can save thousands of lives per
`ear on US. highways.
`
`1984 Transportation Secretary, Elizabeth Dole. mandated
`tomatic crash protection for passenger cars. Today. a congres-
`onal mandate requires one hundred percent of vehicles sold in
`e United States in l999 be equipped with both driver side and
`sscnger side airbags. Consideration is now being given to rear
`-at occupants as well as possible protection from side impact
`' rough the use of several emerging technologies.
`
`RW and Morton International are two of the several major
`nufacturers of airbag deployment systems. The key functional
`ments of an airbag system are the initiator. intlator, airbag pil-
`. reaction housing. deployment door! cover. gas generate and
`§['.I'.
`
`the. following. reference will be made to doors and covers.
`ors are being referred to as passenger side systems and
`ers are being referred to as driver side systems.
`
`I durability and pe.rl’ot'imutce requirements for airbag doors
`covers dictates that the structural design, materials used, and
`ufactu ring processes are very important considerations in the
`lopment of this component. Injection molded plastic, due to
`Ibility to meet the strict iequirements, is playing a major role
`development of the deployment doorfeover.
`
`

`
`This tear seam does not create any type of read through
`from the appearance side of the part‘.
`
`Although this design solves two very significant prol}
`lem, that being the read through and elimination of a
`visible tear seam. it does generate a few other concerns,
`
`The first concern being. that now the entire dynamic
`force is concentrated at a single attaclnnent flange. This
`means that there is more than double the dynamic load
`on the flange that was experienced with a center tear
`seam. The center tear seam was in effect two doors
`
`opening in opposite directions with only one half the
`mass on each door and two attachment‘ flanges to
`absorb the energy.
`
`Several methods have been developed to reinforce the
`single attachment llange to sustain the increased loati
`One method is the introduction of an insert molded
`
`scrim or rnetal stamping into the back side of the part
`Obviously. these additions create an undesirable eco-
`nomic impact on the cost of the door. however. in cer-
`tain cases the introduction of metal, used in conjunction
`with a lower cost plastic resin can create a favorable
`economic condition.
`
`A second concern is that often the design dictates mov-
`ing the tear seam downward and away from itrunediate
`contact with the second surface of the door, See Figure 3A.
`In this case, a wall of approximately 50% of the door
`thickness connects the attachment flange and tear seam
`to the door. This 50% thickness section of wall remains
`
`on the door during deployment of the airbag. The airbag
`
` Door hinge area
`
`
`
`X
`
`2Dfo30%otX
`
`Tecrr location
`
`Scrtrrt or metal reinforcerrient
`
`Attachment flanges
`
`
`
`
`
`
`Fig. 3: Hidden tear seam
`
`
`
`20 to 30°}. of X
`
`Tear location
`
`tion of screws, rivets. or fasteners, thereby reducing the cost and
`complexity of the system.
`
`location & Design of the Tear Seam
`
`There are three types of tear seams.
`
`A. Visible
`
`B. Hidden
`
`C.
`
`Invisible
`
`A. Visible Tear Scams are the most common type used
`today. See Figure 2. With this design there is usually an
`indented groove in the first surface of the door or cover.
`This groove is placed directly over a thinned area on the
`second surface of the part. The purpose of the groove is
`to hide a read through of the second surface thin out
`area. which commonly occurs in injection molded parts
`where the wall thickness is abruptly changed on the
`second surface of the part.
`
`B.
`
`I-iidder-i Tear Seams are also quite common today on
`passenger side doors. This design offers a solution to
`the read through problem outlined in visibic tear seams,
`see Figure 3.
`
`Because there is no tear seam on the appearance surface
`of the part, no road through problem is created. Inherit
`to this design. the tear seam is moved on to the rear-
`ward artachment flange at the intersection of that flange
`to the second surface of the part. The [ear scam area is
`reduced to 20 to 30% of the wall thickness of the door.
`
`\It'tllIntrt¢|contarlcnrnunrn.tl-tocmataur
`allhadoorccmaauti-bngcrurmrnaut
`Frucftarepctntot
`
`............7
`
`Temoflllunge I'rut:t-are point
`Buck slda (znct) surtuce
`
`Attachment it
`Item otf Iiurlgeuflge 0'
`
`Fig. 1: Contour of the door may cause airbag entrapment
`
`Appearance (tat) surface
`
`Fig. 2: Visibie tear seam
`
`Fig. 3a: Detail of the hidden rear seam
`
`36 I Automotive Body Interior & Safety Systems I IBEC ’94
`
`
`
`

`
`
`
`tends to be entrapped by this wall thereby, creating a
`force that wants to shear that "flange from the door. To
`resolve this concern additional 45 degree gusset ribs
`must be added to reinforce that wall so cracking and
`fragtrtentation of that wall does not occur. During
`airbag deployment. the additional gusset ribs have
`proven atleqnate to retain the rib to the door. however,
`this creates an entrapment problem for the airbag and
`thus. the force applied to the single attachment flange
`on the opposite side of the door is dramatically
`increased. Depending on the height of this rib, rein—
`forcement of the forward attachment flange may again
`be required.
`
`C.
`
`irlt‘iSi!'Ji£’ Tear Sermis are the. most desirable of all
`
`designs. It has been demonstrated that it is possible and
`practical, to injection mold ti driver side cover in a sin-
`gle molding process using a single shot material utiliz-
`ing invisible tear seams. Mayco has successfully con-
`cluded a program with one of the big three auto makers
`on a program of this type. Sttccesslitl deployments were
`obtained on the first deployment tests.
`
`As ofthis date, it has been difficult to accomplish invis-
`ible tear seams through the injection molding process
`on passenger side doors. without the introduction of a
`second layer of TPE that is over molded in a second
`shot operation onto a first shot molded substrate. see
`Figures 4 and 4a. The advantage of this type of two shot
`molded part is that appearance imperfections visible in
`the first shot substrate are covered by the second shot
`TPE. In addition, using TPE with a shore A hardness of
`50 dttrometer when molded onto a semi-rigid substrate
`matches the hardness of the soft instrument panel cover
`material.
`
`The significant advantages of the Mayco invisible tear seam
`designs are:
`
`1.
`
`2.
`
`3.
`
`Surface shape design flexibility
`
`Improved performance
`
`Improved appearance
`
`4.
`
`Simplicity of operation at minimum cost.
`
`Surface Shape Design Flexibility
`
`For driver side covers of :1 single material, single shot design.
`invisible tear seams are difficult to achieve in many cases. The
`reason Ior this is that several gates are required into a single part
`in order to create the proper tlow direction of the. plastic as it
`enters the cavity of the mold. Due to the shape of the part and
`cosmetic constraints the ideal gate locations may not be allowed
`by the automobile manufacturer.
`In addition. one of the major
`factors in being able to mold a cosmetically pleasing pan is that
`equal flow lengths from each gate is highly desired. Therefore, if
`the part is rectangular like must driver side Covers, it is estren1e—
`ly difficult to achieve equal flow lengths.
`
`Two shot covers or doors are able to be produced with less diff"—
`culty. Using Mayco"s Plastics Inc. design, the second shot TPE.
`material covers the Cosmetic problems present on the first shot
`
`TPE soft cover (2nd shot)
`
`Rigid substrate (131 shot)
`
`Fig. 4: Soft‘ cover molded over a rigid substrate
`
`Fig. 4a: ‘H’a.-id ’U' style tear seams shown
`
`substrate and no flow problems exist vi ith the TPE man-nat. As 3
`result. the stylist can now develop V3.f'lCtLlf‘~' shapes with-out con-
`cern of encountering undesirable cosmetic in1pcrl'cction_-..
`
`Most passenger side doors are rectangular in shape and there-
`fore, single material, single shot doors. like the driver side cov-
`-ers, are difficult to produce in most" cases.
`
`Two material, two shot passenger side doors like driver side cov-
`ers are able to be produced with much less difficulty for the
`same reasons as two shot driver side covers.
`
`improved Door Performance
`
`Since the tear seam is invisible, the desired tear seam location
`can be selected for optimum performance. This usually means
`that an ‘H’ shape tear seam. which creates two doors upon Frac-
`ture of the tear seam. is desired. With this design each door is
`approximately U2 of the total door area. Also each door has it’s
`
`IBEC ’94 - Automotive Body interior .8.» Safety Systems - 8.7
`
`

`
`own separate hinge point. As a result. the dynamic energy exerts
`itself at two hinge points rather than one. This results in the
`attachment flanges having to absorb less than 13 of the energy
`of a door that has only a single hinge point. The end results are
`lower airbag pressures and "faster deployment speeds.
`
`f—
`
`improved Appearance
`
`Since no visible lines are present the appearance is greatly
`improved. tn addition, the passenger side area offers the oppor-
`tunity, with this design and process. to design the door as an
`integral part of the instrument panel soft topper pad. This results
`in no visible lines showing the outline of the door pcrirneter and
`therefore, eliminates any concern for the fit of a separate door as
`well as squeaks and rattles caused by two components.
`Variations in color, gloss and texture are also not a concern
`when using this design. With these concerns eliminated. the styl-
`ist is Free to create almost any shape desired. Also. since an inte-
`gral passenger door and topper pad is possible. the door now
`does not need to be attached to the airbag deployment system,
`thus allowing greater dimensional variations within the vehicle
`in that area. The complete topper pad of the instrument can be
`shipped to the assembly plant as a separate item. Upon assembly
`to the vehicle, the topper pad with integral deployment door.
`overlaps the deployment module thereby allowing for greater X,
`Y & Z dimensional variances between the module and the door.
`
`Simplicity of Operation of Minimum Cost
`
`The invisible tear seam proposed relies on a simple tensile fail-
`ure of the plastic in the tear seam area. The force required to ini-
`tiate this tensile failure can be a very easily controlled, since
`with injection molding, a very repeatable tear seam tlrickness can
`be obtained. For this reason, the amount of force required to
`cause the tensile failure in the tear scam by the inflating airbag
`pressing against the backside of the tear seam can be maintained
`within a very narrow range.
`
`There are no additional secondary operations performed on the
`tgar seam or auxiliary systems that weaken the tear seam prior to
`airbag deployment that could introduce variation to the system
`performance or increase the system cost.
`
`4°
`
`7
`
`§
`§ an
`§ In —-
`g 0 —J-
`
`{
`l
`
`l
`l
`
`.
`3
`
`I
`
`F-t
`
`‘
`
`-1.
`
`..
`‘
`
`"3'
`
`-I—
`E‘ -—:t-_________ ___,r'_._._
`
`_m
`
`n
`
`5
`
`I
`to
`
`Is
`
`an
`
`25
`
`so
`
`as
`
`an
`
`.
`-as
`
`so
`
`limetmllllseconds)
`
`'jT"1
`AirBi::gPressure
`
`,
`
`Tl
`
`Peal: Pressure: 35.15 peig
`
`l__
`
`Fig. 5: Air bag pressure vs. inflation time
`
`this shock to as much area as possible. Localized fasteners s
`as rivets or screws are usually insufficient‘ to withstand th‘
`shock unless they are combined with steel plates to help dism
`me the load.
`
`The type of materials selected also has a major effect on
`attachment system. Soil materials with low flex modulus val
`require additional area for retention. I-Iigh flex modulus mate
`als tend to crack and break especially at low temperatures wifl
`the shock of the deployment.
`
`Methods of Attachment
`
`Selection of Material
`
`Methods of attachments of driver side eove.rs and passenger side
`doors to the deployment system andfor surrounding components
`vary widely and are usually influenced by the design of the sys-
`tem. the type of material the doorfdover is made of and personal
`preference of the system supplier. One thing that is universally
`common between system suppliers is that fasteners such as
`screws, rivets or rivet plates and additional components are
`attempted to be minimized or completely avoided as a means of
`retaining the doorfcover to the deployment module. Doors and
`covers that are snapped into place, or are combined with other
`assembly operations of the module assembly are preferred. The
`fact that the bag pressure rapidly increases from zero to some-
`times as high as 0.3 MPa (50 psi"). see Figure 5, within a few
`milliseconds demonstrates that the attachment system needs to
`he very strong in order to absorb the shock of the deployment.
`For that reason. it is advisable to spread out the load created by
`
`88 0 Automotive Body interior & Safety Systems t IBEC '94
`
`The OEM nianufactuners have traditionally dictated the ntateri
`specification for the desired surface appearance and degree at
`softness of the SIR system.
`
`If a single shot hard door or cover is desired there are severfl
`materials which have been developed for this application. So
`of the current materials used for these applications are:
`
`D & S Plastics Dexllex 756-67 and 756-5? TPO
`
`Union Carbide DEFA lll47BI(_. TPO
`
`DuPont DYM 100 and 500 thermoplastic polyester
`elastomer.
`
`In some cases, such as top mounted passenger side doors, some-
`materials may need to be supported by reinforcements that may
`be molded into the door or assembled in a secondary operation
`al’tc.r the door is molded. This is necessary as a result of the low
`
`

`
`flex modulus and low heat deflection properties. (as low as
`83 MPa (11000 psi} flex modulus and as low as approximately
`60°C (l40°F) heat deflection temperature). ll5°C (?.40°F) tem-
`peratures are experienced in this area.
`
`In other cases such as driver side covers, and front mounted pasv
`senger side doors, auxiliary support of these materials is rarely
`required given that the proper design is engineered. The most
`obvious reason that this is true is that these parts usually have
`more shape to support themselves and lower temperatures are
`experienced in these areas of the vehicle. approximately
`82°C t 1 80°F}.
`
`If a soft door or cover is desired a two shot molded part must be
`produced. In order to achieve the desired results, some of the
`plastic materials used are different than what is used in single
`shot parts.
`
`The materials most often used for the first shot substrate are:
`
`D & S Plastics, Dexflex 756-67 or 756-57. TFO
`
`Union Carbide. DEFA l047BI(, TPO
`
`Conclusion
`
`By utilizing the injec.tion molding process:
`
`E*‘!‘'-‘:‘'
`
`The parts possess higher quality.
`Manufacturing scrap rates are significantly reduced.
`The dimensional consistency increases due to the injec—
`tion molding process.
`4. Manufacturing efficiency is improved due to higher
`tooling production capacity.
`5. Greater design flexibility exists.
`
`The result is that significant economic savings are obtained.
`
`The value of the dual layer deployment door design is recog-
`nized by all OEM company's and their major restraint system
`suppliers.
`
`Over a half million two shot molded doors with hidden tear
`seams are on production vehicles today and construction of addi-
`tional tools is currently under way for new programs. Additional
`programs for invisible tear seam parts are currently in various
`stages of completion at this time.
`
`__.__:_____._______
`
`DuPont Bexloy, Ethyleneflt/lethacrylic Acid
`
`Biography
`
`The materials most" often used for the second shot cover are:
`
`Multibase RP6568 Thermoplastic Elastomer
`
`Teknor Apex Tekron 4-’ltlt}-4ll
`
`Through the innovative use of these materials. a unique hinge
`function is achieved. A layer of styrenic thermoplastic elastomer
`for the first shot substrate and a thinner layer of Ihennoplaslic
`olefin elastomer for the second shot outer cover are used to con—
`struct a part with application temperature ranges from
`-40°C (40°F) to +1 15°C (240°F). This specially formulated
`styrenic thermoplastic elastomer possesses at very low glass tran-
`sition temperature of and superior elasticity and ductility at In“
`temperatures. The unique thermoplastic olefin elastorner has
`high impact strength at elevated tcmpcrattlres. When these two
`layers of elastomers are combined. the hinge point moves along
`an are contingent upon the parts service temperature. This
`unique hinge provides for balanced performance between
`-40°C‘. (- 40°F) to +l l5°C (240°F). For the first time. the dual
`layer structure and moving hinge theory has been applied in
`designing an airbag deployment Door.
`
`Coatings
`
`A two component polyurethane paint system produced by Akzo
`Industrial Coatings, Sherwin Williams, Bee Chemical and others
`are currently being used in one and two mil dry film thickness
`coating. These coatings are capable of achieving a surface with a
`leather—like feel and look. The coatings are capable of meeting
`the ultraviolet light resistance as required for automotive interior
`applications and have been used successfully in automotive
`applications for several years.
`
`waterborne coatings are currently under development for these-
`applications as well.
`
`
`
`Mr. James Zweng r‘rtm:=rtti_t' holu'.r the posi-
`tion of Vice Presidem o_,I"Eugiin=r=riitg or
`Mrr_\-‘i.‘r.J PitJ5t‘ft"5‘. Int‘.
`
`Mr. Zirerrg has been i'n1'ot't‘m’ in t'ir;'t'c'rit:ir
`ill-r:)i’t'J‘l".I'it.!3 .sim‘e ('96-if n'l.=ere he in.r'.ri'ol'i_\'
`began as a mold d¢-.s-r';:ne:- for C‘w'1'er
`Errzioorrotz. a Detroit heme? rrxrlbig mm-
`PW")
`
`
`
`III I906 in formal _Un's:l1'jI P3413-3.. I
`l|tu1':n.Mirh:=I unfit}-. 0&0}:-H-
`-: aqiruun -andpun-aifirtr:-
`an--e -chart. flu fin -fnrjlgfi
`aa-2-, n-n'4{_uu-s=u:.fiCj-
`--;:t'.'u'r.'.' ~"r-'I-: -we.-=-...—‘.-"J: p’-Ecu-
`
`;,. _.m_.-..t in. J/,JJl-I'1J-' u.._....P-_a=. . in Fran ua......_. _-xi
`
`mt‘-‘r. Hi-. ;.‘r:tr:.-rt} rum r.-.1-2'-arr 3- in-Jafi Jr: DT
`int: fnfatti‘ and ‘I’! s'r-.t- :' Iirr rmzrn-:1-.-.-.: .fir:!hrlIIrI D l"§7b
`Hmtcd to H: -' Pr't'.Ud’c'rn'
`.-_.' Engineering 1' II’-tr r I111!‘
`Ste:'!i‘ni,v Ht'i_;Jli:_\, ‘|t‘:.-f:.f;..*rr In 2'45-9 Hr. Irv!‘ _-can-at g Ivy.“
`rict‘e[o,rr.=ncvn ;Jmnp .1:
`'H.:_-.:«- ‘.-'.-.r riir _-nip-u-ac -a 31¢‘-jfl
`Doom rmd C'r':iw'_r_,riir the srsir.-.‘r:I.-in i r hulnirn
`
`
`
`IBEC "94 0 Automotive Body Interior & Safety Systems - 89