Patent Publication Number: US-2018038469-A1

Title: Method Of Making Composite Camshafts

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application No. 62/370,268 filed on Aug. 3, 2016. The entire disclosure of the above application is incorporated herein by reference. 
    
    
     FIELD 
     The present disclosure relates to making composite camshafts for internal combustion engines. 
     BACKGROUND 
     This section provides background information related to the present disclosure which is not necessarily prior art. 
     Laser welding is commonly used to weld plastic parts together. One type of laser welding is through transmissive laser welding such as through transmissive infrared laser welding, commonly referred to as TTIr. During TTIr welding, a transmissive plastic part and an absorptive plastic part are held together with a force with abutting surfaces at a weld interface in good contact with each other. Laser radiation of a suitable wavelength is passed through the transmissive part and impacts the absorptive plastic part at the weld interface and gets converted to heat by absorption by the absorptive part. This heats the absorptive plastic part at the weld interface which is heated above a melting temperature. As the absorptive plastic part melts, the heat is transferred across the weld interface to the transmissive part melting the transmissive part at the weld interface forming a molten weld at the weld interface. Once the laser is turned off, the molten weld solidifies welding the parts together at the weld interface. It should be understood that the transmissive part is also known in the art as a transparent part. It should also be understood that the absorptive part includes parts that are partially absorptive to the laser radiation. 
     One type of TTIr available from Branson Ultrasonics Corporation is simultaneous through transmissive infrared welding referred to herein as STTIr. In STTIr, the full weld path or area (referred to herein as the weld path) is simultaneously exposed to laser radiation, such as through a coordinated alignment of a plurality of laser light sources, such as laser diodes. An example of STTIr is described in U.S. Pat. No. 6,528,755 for “Laser Light Guide for Laser Welding,” the entire disclosure of which is incorporated herein by reference. 
     In STTIr, the laser radiation is typically transmitted from one or more laser sources to the parts being welded through one or more optical waveguides which conform to the contours of the parts&#39; surfaces being joined along the weld path.  FIG. 11  shows an example of a STTIr laser welding system  1100 . STTIr system  1100  includes a laser support unit  1102  including one or more controllers  1104 , an interface  1109 , one or more power supplies  1106 , and one or more chillers  1108 . STTIr laser welding system  1100  also includes an actuator  1110 , one or more laser banks  1112 , an upper tool/waveguide assembly  1114  and a lower tool  1116  fixtured on a support table  1118 . Laser support unit  1102  is coupled to actuator  1110  and each laser bank  1112  and provides power and cooling via power supply (or supplies)  1106  and chiller (or chillers) to  1108  to laser banks  1112  and controls actuator  1110  and laser banks  1112  via controller  1104 . Actuator  1110  is coupled to upper tool/waveguide assembly  1114  and moves it to and from lower tool  1116  under control of controller  1104 . The parts to be welded are placed in an upper tool/waveguide assembly  1114  and a lower tool  1116 . 
     As best shown in  FIG. 12 , each laser bank  1112  includes one or more channels  1122  with each channel  1122  having a laser light source  1124  of laser radiation, which may illustratively be a laser diode. Each channel  1122  is coupled by a fiber bundle  1126  to a waveguide  1128  of upper tool/waveguide assembly  1114 . Waveguide  1128  is fixtured in an upper tool  1130  of upper tool/waveguide  1114 . Each fiber bundle  1126  splits into one or more legs  1132  with each leg terminating in a ferrule  134  at waveguide  128 . (For clarity of  FIG. 12 , only two ferrules  1134  are identified by reference number  1134  in  FIG. 12 .) While not shown in  FIG. 12  for clarity of  FIG. 12 , it should be understood that there are sufficient laser banks  1112  with associated channels  1122 , fiber bundles  1126  and legs  1132  terminating in ferrules  1134  so that there are ferrules  1134  around the entire weld path defined by waveguide  1128 , such as around the entire periphery of waveguide  1128 , sufficient to radiate the entire weld path around with laser light. Each laser channel  1122  is controlled by controller  1104 . It should be understood that each leg  1132  typically has several fibers that are part of one of the fiber bundles  1126  so that each ferrule is fed laser light by these several fibers of the associated fiber bundle  1126  from the laser light source  1124  of laser radiation of the laser channel  1122  to which the leg is coupled via the associated fiber bundle  1126 . 
     Camshafts are used in internal combustion engines to mechanically open and close valves that let the air/fuel mixture into the cylinders of the engine and the exhaust out of the cylinder. The camshaft has cams on it, also called lobes, that push against the valves via valve lifters as the camshaft rotates the cams to valve opening positions to open the valves. Springs return the valves to their closed position as the cam shaft rotates the cams past the valve opening positions. 
     Typically, camshafts are made of machined steel parts.  FIG. 1A  shows an example of such a camshaft  10  and  FIG. 1B  shows an exploded view of a portion of camshaft  10 . Camshaft  10  has a core shaft  12 , a plurality of cams  14  (only some of which are identified with reference number  14  in  FIG. 1 ) formed integrally with core shaft  12  or affixed to core shaft  12 , a plurality of bearing assemblies  166  (two of which are identified with reference number  16  in  FIG. 1 ) affixed to core shaft  12  and at least one load introduction part  18  formed integrally with core shaft  12  or affixed to core shaft  12 . As used herein, a load introduction part is a component that bears a load, such as a load transmitted from another component such as the crankshaft, transmitting a load to another component such as a pump, or provides load support such as a mounting flange. In an aspect, the at least one load introduction part  18  includes a mounting flange  20 . In an aspect, the at least one load introduction part  108  includes a timing gear  22  ( FIG. 1B ). 
     In an effort to reduce weights, camshafts have been made of fiber composite material. U.S. Pat. No. 9,574,651 (that claims priority to DE 10 2013 111 837 A1) for “Lightweight Camshaft and Method for Producing the Same” discloses a process for assembling a camshaft in composite fiber technology with mounted individual components. 
     DE 102 60 115 B4 for “Method for Producing a Shaft and a Shaft Produced According to this Production Method” discloses a camshaft and method for producing the camshaft by producing a tubular base body from a carbon fiber composite material, in which metal sleeves are incorporated to receive and join cam elements. WO 2016/030134 A2 for “Method for Producing a Joint on a Component Consisting of a Fibre-Composite Material) discloses joining multiple fiber composite structures to one another with metal connecting pieces. 
     SUMMARY 
     This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features. 
     In accordance with an aspect of the present disclosure, a method of making a camshaft for an internal combustion engine includes laser welding a plurality of cams and a plurality of bearing assemblies to a fiber composite support tube. The method includes providing a fiber composite support tube having a plurality of weld locations and providing each weld location with a plastic laser weldable material. It also includes providing a plurality of cams, providing each cam with a laser weldable portion and providing each laser weldable portion of each cam with a plastic laser weldable material. It further includes providing a plurality of bearing assemblies, providing each bearing assembly with a laser weldable portion and providing each laser weldable portion of each bearing assembly with a plastic laser weldable material. It further includes placing the plurality of cams on the fiber composite tube with each cam at a respective one of the weld locations with the plastic laser weldable material of the cam abutting the plastic laser weldable material of the weld location at which that cam was placed and placing the plurality of bearing assemblies on the fiber composite support tube with each bearing assembly at a respective one of the weld locations with the plastic laser weldable material of the bearing assembly abutting the plastic laser weldable material of the weld location at which that bearing assembly was placed. It further includes providing laser tooling that is split laser tooling for each cam and for each bearing assembly with each laser tooling associated with one of the cams or one of the bearing assemblies. It further includes closing the split tooling of the laser tooling associated with each cam or bearing assembly around the fiber composite support tube adjacent that cam or bearing assembly with which that laser tooling is associated and urging that cam or bearing assembly with that laser tooling against the associated weld location of the fiber composite support tube. It further includes generating a plurality of sets of laser beams with laser light sources of a simultaneous through transmissive infrared laser welding system with each laser beam having laser light at an absorption wavelength and with each set of laser beams associated with a respective one of laser tooling. It further includes directing each set of laser beams to the laser tooling with which that set of laser beams is associated and with that laser tooling directing that set of laser beams to a weld path at a weld interface at which the cam or bearing assembly associated with that laser tooling is welded to the associated weld location of the fiber composite support tuber to simultaneously radiate the entire weld path with laser light at the absorption wavelength. 
     In an aspect, the method also includes laser welding at least one load introduction part to an end of the fiber composite support tube including providing the load introduction part member with a laser weldable portion, providing the laser weldable portion of the load bearing member with plastic laser weldable material, placing the load introduction part member adjacent an end of the fiber composite support tube, providing laser tooling for the load introduction part that is associated with the load introduction part member with at least one of the sets of laser beams associated with that laser tooling associated with the load introduction part, disposing laser fiber bundles of the simultaneous through transmissive infrared laser welding system in the laser tooling associated with the load introduction part with ends of fibers of the laser fiber bundles in bores of an outer welding ring that are circumferentially spaced around a circumference of the outer welding ring, placing a housing of the laser tooling associated with the load introduction part member in a cylindrical opening of the fiber composite support tube, and directing the set of laser beams associated with the laser tooling associated with the load introduction part member to that laser tooling and directing these laser beams outwardly from the ends of the fibers of the fiber bundles to a weld path at a weld interface at which the load introduction part associated with that laser tooling is welded to the associated weld location of the fiber composite support tuber to simultaneously radiate the entire weld path with laser light at the absorption wavelength. 
     In an aspect, providing each bearing assembly includes providing a bearing and at least one bearing cage associated with that bearing, providing each bearing assembly with the laser weldable portion with the plastic laser weldable material includes providing the bearing cage with the laser weldable portion with the plastic laser weldable material, placing each bearing assembly on the fiber composite support tube includes placing the bearing and bearing cage of each bearing assembly on the fiber composite support tube with the bearing cage adjacent the bearing, closing the laser tooling associated with each bearing assembly includes closing it around the fiber composite support tube adjacent the bearing cage of that bearing assembly and urging that bearing cage with that laser tooling against the associated weld location of the fiber composite support tube. 
     In an aspect, providing each bearing assembly includes providing a bearing and a pair of bearing cages associated with that bearing and placing each bearing assembly on the fiber composite support tube includes placing the bearing and bearing cages of each bearing assembly on the fiber composite support tube with the pair of bearing cages adjacent opposite sides of the bearing. 
     In an aspect, providing each laser weldable portion of each cam with laser weldable material includes providing plastic laser weldable material that is transparent to the laser beams, providing each bearing assembly with plastic laser weldable material includes providing plastic laser weldable material that is transmissive to the laser beams and providing the weld locations associated with the cams and with the bearing assemblies with plastic laser weldable material includes providing plastic laser weldable material that is at least partially absorptive to the laser beams. 
     In an aspect, providing the plastic laser weldable material that is transparent to the laser beams includes providing one of thermoset and thermoplastic material that is transparent to the laser beams and providing the plastic laser weldable material that is partially absorptive to the laser beams includes providing one of thermoset and thermoplastic material that is partially absorptive to the laser beams. 
     In an aspect, providing the weld locations with plastic laser weldable material includes providing the plastic laser weldable material as an outer layer of the fiber composite support tube. 
     In an aspect, providing the plastic laser weldable material as the outer layer of the fiber composite support tube includes providing a thermoset or thermoplastic material that is transparent or partially absorptive to the laser beams as the outer layer of the fiber composite support tube. In an aspect, providing the thermoset or thermoplastic material as the outer layer of the fiber composite support tube includes providing as the outer layer of the fiber composite support tube a second tube of the thermoset or thermoplastic material that is transparent or partially absorptive to the laser beams. 
     In an aspect, the method further includes providing an interface sheet around the outer layer of the fiber composite support tube wherein the interface sheet is made of a thermoset or a thermoplastic material that is transparent or partially absorptive to the laser beams around the outer layer of the fiber composite support tube. 
     In an aspect, the method includes forming recesses in the fiber composite support tube at one or more of the weld locations and filling the recesses with a thermoset or thermoplastic material that is transmissive or partially absorptive to the laser beams. 
     In an aspect, providing the plurality of cams includes providing cams that only partially encircle the fiber composite support tube when the cams are placed on the fiber composite support tube. 
     Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
    
    
     
       DRAWINGS 
       The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure. 
         FIG. 1A  shows a prior art metal camshaft and  FIG. 1B  shows an exploded view of a portion of the camshaft of  FIG. 1A ; 
         FIGS. 2A-2E  to show embodiments of a cam and fiber composite support tube of a composite camshaft and showing a material finish of the fiber composite support tube and a reinforced fiber layer in accordance with an aspect of the present disclosure in which  FIG. 2A  is a cross-section of a portion of the composite camshaft having a cam laser welded to the composite support tube,  FIG. 2B  is a side view of a portion of the composite cam shaft having a cam laser welded to the composite support tube,  FIGS. 2C and 2D  are perspective side views of a portion of the composite support tube with a laser weldable outer layer thereon, and  FIG. 2E  shows a matrix of polymer material in which reinforcing fibers are embedded of which the composite support tube is made in accordance with an aspect of the present disclosure; 
         FIGS. 3A-3D  show embodiments of a cam and fiber composite support tube of a composite camshaft in accordance with an aspect of the present disclosure and showing diagrammatically laser welding thereof in which  FIG. 3A  is a side view of a portion of the composite support tube,  FIG. 3B  is a cross-section of a portion of the composite camshaft having a cam laser welded to the composite support tube,  FIG. 3C  is a side view of a portion of the composite cam shaft having a cam laser welded to the composite support tube and  FIG. 3D  is a side view of a portion of the composite cam shaft showing diagrammatically laser welding of the cam to the composite support tube; 
         FIGS. 4A and 4B  show an embodiment of a cam and fiber composite support tube of a composite camshaft in accordance with an aspect of the present disclosure in which  FIG. 4A  is a cross-section of a portion of the composite camshaft having a cam laser welded to the composite support tube and  FIG. 4B  is a side view of a portion of the composite cam shaft having a cam laser welded to the composite support tube; 
         FIGS. 5A and 5B  show an embodiment of a cam and fiber composite support tube of a composite camshaft with the cam only partially encircling the fiber composite support tube in accordance with an aspect of the present disclosure in which  FIG. 5A  is a cross-section of a portion of the composite camshaft having a cam laser welded to the composite support tube and  FIG. 5B  is a side view of a portion of the composite cam shaft having a cam laser welded to the composite support tube; 
         FIGS. 6A and 6D  show an embodiment of a cam and fiber composite support tube of a composite camshaft with an interface layer around the fiber composite support tube in accordance with an aspect of the present disclosure in which  FIG. 6A  is a cross-section of a portion of the composite camshaft having a cam laser welded to the composite support tube,  FIG. 6B  is a side view of a portion of the composite cam shaft having a cam laser welded to the composite support tube,  FIG. 6C  is a side view of a portion of the composite cam shaft showing diagrammatically laser welding of the cam to the composite support tube, and  FIG. 6D  is a section along line  6 D of  FIG. 6B  of a portion of a periphery of the composite support tube and interface layer where a portion of the cam is laser welded to the composite support tube; 
         FIGS. 7A-7E  show an embodiment of a cam and fiber composite support tube of a composite camshaft with the fiber composite support tube having recesses filled with plastic laser weldable material in accordance with an aspect of the present disclosure in which  FIG. 7A  is a cross-section of a portion of the composite camshaft having a cam laser welded to the composite support tube,  FIG. 7B  is a portion of the composite support tube having one of the recesses,  FIG. 7C  shows the recess of  FIG. 7B  filled with the plastic laser weldable material,  FIG. 7D  shows schematically the laser welding at the recess of  FIG. 7C  and  FIG. 7E  is a side view of a portion of the composite cam shaft having a cam laser welded to the composite support tube; 
         FIGS. 8A and 8B  show diagrammatically laser welding of cams to a fiber composite support tube of a composite camshaft in accordance with an aspect of the present disclosure; 
         FIGS. 9A-9D  show diagrammatically laser welding of bearing assemblies to a fiber composite support tube of a composite camshaft in accordance with an aspect of the present disclosure; 
         FIGS. 10A and 10B  show diagrammatically laser welding of a load introduction part to a fiber composite support tube of a composite camshaft in accordance with an aspect of the present disclosure; and 
         FIGS. 11 and 12  show a prior art simultaneous through transmissive infrared laser welding system. 
     
    
    
     Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings. 
     DETAILED DESCRIPTION 
     Example embodiments will now be described more fully with reference to the accompanying drawings. 
     Example embodiments are provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail. 
     The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms “a,” “an,” and “the” may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises,” “comprising,” “including,” and “having,” are inclusive and therefore specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed. 
     When an element or layer is referred to as being “on,” “engaged to,” “connected to,” or “coupled to” another element or layer, it may be directly on, engaged, connected or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly engaged to,” “directly connected to,” or “directly coupled to” another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. 
     Although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as “first,” “second,” and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example embodiments. 
     Spatially relative terms, such as “inner,” “outer,” “beneath,” “below,” “lower,” “above,” “upper,” and the like, may be used herein for ease of description to describe one element or feature&#39;s relationship to another element(s) or feature(s) as illustrated in the figures. Spatially relative terms may be intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the example term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly. 
     It should be understood that arrows in the figures that are not specifically identified with a reference number indicate the incidence of laser light if shown coming from a laser light source or the direction of force if shown with arrows labeled with F. 
       FIGS. 2A-2E to 7A-7B  show example embodiments of cam  104  and fiber composite support tube  102  of a composite camshaft  100 . 
     A cam  104  affixed to fiber composite support tube  102  and the structures of fiber composite support tube  102  and cam  104  are shown in more detail in  FIGS. 2A-2E, 3A-3D and 4A-4B . Fiber composite support tube  102  has a core fiber composite tube  200  with a laser weldable outer layer  202  affixed to an outer surface  204  of fiber composite support tube  102 . Laser weldable outer layer  202  includes a plastic material that is laser weldable, as discussed in more detail below. In the example of  FIGS. 2A-2E , laser weldable outer layer  202  illustratively has an inner thermoset layer  206  of a thermoset material and an outer layer  208  of a thermoplastic material. The thermoplastic material of which outer layer  208  is made is laser weldable. It should be understood that laser weldable outer layer  202  could be a single layer of a laser weldable thermoset material or a laser weldable thermoplastic material, as shown in the embodiment of  FIGS. 3A-3D . Laser weldable outer layer  202  is illustratively applied to core fiber composite tube  200  after core fiber composite  200  is fabricated, for example, by injection molding the material used for laser weldable outer layer  202  around core fiber composite tube  200 . It should be understood that processes other than injection molding can be utilized to apply the material of which laser weldable outer layer  202  is made to core fiber composite tube  200 . 
     Core fiber composite tube  200  is made of a matrix  210  of polymer material in which reinforcing fibers  212  (best shown in  FIG. 2E ) are embedded and retained. The matrix of polymer material  210  can be a matrix of thermoset material such as epoxy, phenolic resin, or similar thermoset material or a matrix of a high-temperature resistant thermoplastic material. Some examples of high-temperature resistant thermoplastic materials that could be used for the matrix of high temperature resistant thermoplastic material include PEEK (polyether ether keton), PPS (polyphenylene sulfide), PPA (polyphthalamide), PI (polymide) and PA (polyamide). In an aspect, the reinforcing fibers  212  are carbon fibers are oriented at a non-zero angle a with respect to a longitudinal axis  215  of core fiber composite tube  200  (best shown in  FIG. 2D ), such as fifteen degrees by way of example and not of limitation. 
     Cam  104  includes an inner stiffening member  214  and laser weldable outer portion  216  in which inner stiffening member  214  is embedded and retained. In an aspect, laser weldable outer portion  216  is made of plastic laser weldable material and in another aspect has an outer layer of plastic laser weldable material. In the example of shown in  FIGS. 2A-2E, 3A-3D and 4A-4B , cam  104  entirely encircles fiber composite support tube  102 . In this example, cam  104  has an inner bore  218  through which fiber composite tube  102  extends. In a variation, cam  104 ′ encircles only a portion a portion of fiber composite tube  102 , as best shown in  FIGS. 5A-5B . Cam  104 ′ of  FIGS. 5A and 5B  is a lighter weight cam than cam  104  since cam  104 ′ has less material than cam  104 . Further, inner stiffening member  214 ′ of cam  104 ′ has a void  500  ( FIG. 5A ) therein further reducing the material of cam  104 ′. Moreover, a central structural region of this half-open cam  104 ′ can additionally be welded at the ends (region of the tube center line) using the laser joining technology, in order to avoid twisting of the cam  104 ′ under load. 
     As discussed above and as discussed in more detail below, cams  104 , bearing assemblies  106  and load introduction parts  108  are laser welded to fiber composite support tube  102 . These components that are laser welded to fiber composite support tube  102  are collectively referred to as welded components. The welded components are placed on fiber composite support tube  102  at locations on fiber composite support tube  102  at which they are to be welded, referred to herein as weld locations  806  ( FIG. 8 ), only two of which are shown in  FIG. 8 . Fiber composite support tube  102  is placed in a simultaneous through transmissive laser welding system and tooling of split tooling sets closed against each of the welded components. Using one of cams  104  as an example and with reference to  FIGS. 3C and 3D , laser tooling  300  (shown schematically in  FIGS. 3C and 3D ) is closed against cam  104  with laser tooling  300  on either side of cam  104  and applying force to cam  104  to force it against fiber composite tube  102 . Laser beams  304  generated by laser light sources  302  (both shown schematically in  FIGS. 3C and 3D ) of the simultaneous through transmissive laser welding system are directed to laser tooling  300  which directs the laser beams to a weld path  400  ( FIGS. 4A-4B ) at a weld interface  402  at which cam  104  is laser welded to fiber composite tube  102  to simultaneously radiate the entire weld path with the laser light at the absorption wavelength. Laser light sources may illustratively be laser light sources  1124  STTIr laser welding system  1100  ( FIG. 11 ). In the example of  FIGS. 3A-3D , the laser weldable outer portion  216  of cam  104  is transmissive at the absorption wavelength and the laser weldable outer layer  202  of fiber composite support tube  102  is partially absorptive at the absorption wavelength. The laser light has a wavelength that is the absorption wavelength.  FIG. 3D  shows schematically directions of incidence of laser beams  304  when they impinge the laser weldable outer portion  216  of cam  104 . 
     The laser weldable outer portion  216  of cam  104  and the laser weldable outer layer  202  of fiber composite support tube  102  are made of plastic materials compatible with being laser welded to each other. For example, they may each be the same thermoplastic material or be thermoplastic materials having comparable melting temperatures. One of the laser weldable outer layer  202  of fiber composite support tube  102  and the laser weldable outer portion of cam  104  is partially absorptive at an absorption wavelength to laser light having the absorption wavelength that is used for the laser welding and the other is transmissive at the absorption wavelength. It should be understood that an additive could be applied at the interface of the laser weldable outer layer  202  of fiber composite support tube  102  and the laser weldable outer portion  216  of cam  104  to provide the partial absorptivity. 
     In a variation as shown in  FIGS. 6A-6D , laser weldable outer layer  202  of composite fiber support tube  102  is a second tube  600  (composed of a thermoplastic/thermoset material composition, composed of a thermoset material, or composed of a thermoplastic material) or a layer sprayed on to fiber composite tube  102  in a two-component injection molding process composed of a thermoplastic/thermoset material combination, composed of a thermoset material, or composed of a thermoplastic material, wherein the laser weldable outer portion  216  of cam  104  is made of the same material as laser weldable outer layer  202 . 
     In a variation shown in  FIGS. 7A-7E , fiber composite support tube  102  includes recesses  700  at one or more of the weld locations  806  filled with a laser transparent material  702  such as in a two component injection molding process. The weld component welded to the fiber composite support tube  102  at each of the weld locations having such recesses  700  are then laser welded, at least in part, to the laser transparent material in the recesses  700 . In this regard, recesses  700  are formed in fiber composite support tube  102  as shown in  FIG. 7B . The recesses  700  are then filled with the laser transparent material as shown in  FIG. 7C . Cam  104  (used as an example), is then laser welded to the fiber composite support tube  102  by at least in part laser welding laser weldable outer portion  216  of cam  104  to the laser transparent material in the associate recesses  700 , as shown in  FIG. 7D  with the resulting welded structure shown in  FIG. 7E . The foregoing method of component preparation and laser welding advantageously ensures a high weld seam quality, since integral laser weld joints can be optimized herewith. If the material melt projects over the surface somewhat, additional anti-slip protection of the cam  104  on the composite support tube  102  is achieved using this method. 
     As discussed above, simultaneous through transmissive laser welding is used to weld the welded components to fiber composite support tube  102 .  FIG. 11 . With reference to  FIG. 8 , the laser welding technology and associated laser tool technology for welding the welded components of composite camshaft  100  to fiber composite support tube  102  are described with reference to laser welding cams  104  to fiber composite support tube  102 . As discussed above, the laser welding technology used is simultaneous through transmission infrared laser welding and utilizes a simultaneous through transmission infrared laser welding system such as simultaneous through transmission infrared laser welding system  1100 , with the modifications discussed herein. A plurality of laser light sources for generating a plurality of laser beams are shown representatively by laser light source  1124 , and which works in an advantageous energy and wavelength range as discussed above. Fiber bundles  1126  transmit the laser beams generated by lasers  1124  to laser tooling  800  which directs the laser beams to the components being welded, which in the example of  FIG. 8  are cams  104  being welded to fiber composite support tube  102 . In an aspect, laser tooling  800  includes an appropriately configured waveguide along the lines of waveguide  1128  discussed above. Laser tooling  800  includes split tooling  802 . When welding cams  104 , laser tooling  800  includes right and left split tooling  802 . Each split tooling  802  is divided into two halves  804  so that split tooling  802  can be opened and closed around composite fiber support tube  102 . 
     Each cam  104  is positioned on fiber composite support tube  102  at the weld location  806  on fiber composite support tube  102  at which that cam  104  is to be welded to fiber composite support tube  102 . In this regard, there is a weld location  806  on fiber composite support tube  102  at which each welded component is welded to fiber composite support tube  102 , with the weld location for each welded component referred to herein as a weld location  806  associated with that welded component. It should be understood that fiber composite support tube  102  can have the laser weldable outer layer  202  only at each weld location  806 . 
     The tool halves  804  of the right and left split tooling  802  of laser tooling  800  associated with each cam  104  are closed around fiber composite support tube  102  abutting opposite sides of the associated cam  104 . The requisite contact pressure of laser tooling  800  split tooling with force F ensures that the cams  104  are optimally pressed on fiber composite support tube  102 . Opening and closing of tool halves  804  takes place by means of a separate electrically/electronically operated mechanism (not shown). The laser tooling associated with each cam  104  is configured such that there is room between adjacent weld locations  806  so that the right and left split tooling of the laser tooling  800  associated with each cam  104  can be arranged to both the left and the right of each cam  104 . While the foregoing has been described with reference to cams  104 , it should be understood that it applies equally to bearing assemblies  106 . 
     Laser welding metal components to fiber composite support tube  102  presents a challenge since the metal components cannot be penetrated by laser beam  304  and thus cannot be directly laser welded to fiber composite support tube  102 . In an aspect, the bearings of bearing assemblies  106  are such metal components (such as bearing  106 ′ shown in  FIG. 9B ) and a method of attaching bearing  106 ′ that is a metal component to composite fiber support tube  102  is described with reference to  FIGS. 9A-9C . The bearing assembly  106  includes metal bearing  106 ′ and at least one laser weldable bearing cage  900 . Metal bearing  106 ′ is placed on fiber composite support tube  102  at the appropriate weld location. Laser weldable bearing cage  900  is placed on fiber composite support tube  102  against each side of metal bearing  106 ′. In an aspect, laser weldable bearing cage  900  is made of a plastic laser weldable material, such as the plastic laser weldable material of which laser weldable outer layer  202  of fiber composite support tube  102  is made and each laser weldable bearing cage  900  is then directly laser welded to laser weldable outer layer  202  of fiber composite support tube  102 . Laser tooling  800  (not shown in  FIGS. 9A-9C ) is also used in laser welding the laser weldable bearing cages  900  to composite fiber support tube  102 . The tool halves  804  of the applicable split laser tooling  802  are closed around composite fiber support tube  102  abutting the laser weldable bearing cage  900  on one side of bearing assembly  106  and the tool halves of the applicable split laser tooling  802  are closed around composite fiber support tube  102  abutting the laser weldable bearing cage  900  on the other side of bearing assembly  106  and the laser weldable bearing cages  900  laser welded to composite fiber support tube  102 . 
       FIG. 9C  shows a bearing assembly  106  that includes a plastic/metal bearing  106 ″. Bearing  106 ″ includes a plastic portion  908  that may for example be an inner race of bearing  106 ″ and is illustratively made of a plastic laser weldable material. In securing bearing assembly  106  to fiber composite support tube  102 , plastic portion  908  of bearing  106 ″ is illustratively laser welded to laser weldable outer layer  202  of fiber composite support tube  102 , laser welded to each laser weldable bearing cage  900 , or laser welded to both laser weldable outer layer  202  of fiber composite support tube  102  and each laser weldable bearing cage  900 . 
     Depending on the choice of process, it is also possible to weld multiple laser welding surfaces (for example, WL 1  and WL 2  to WLX) in one work operation, as illustrated in  FIG. 9D . 
     The load introduction parts  108 , such as gears and flanges, that must be joined to the fiber composite support tube  102  present a challenge in the technology of joining to camshafts. Because these load introduction parts are generally at the beginning or end of the composite camshaft  100 , it is possible to employ joining techniques such as lasers to weld the load introduction parts to the fiber composite support tube  102 , as now described with reference to  FIGS. 10A and 10B . In this regard, fiber composite support tube  102  has an laser weldable inner layer  1022  ( FIG. 10B ) made of plastic laser weldable material of the same type as the plastic laser weldable material of which laser weldable outer layer  202  of fiber composite support tube  102  is made and load bearing part  108  has a corresponding laser weldable portion  1024  made of plastic laser weldable material compatible with being laser welded with the plastic laser weldable material of laser weldable inner layer  1022 . 
     Laser tooling  1000  has a housing  1002  having an outside diameter  1004  that corresponds to an inside diameter  1006  of an inner cylindrical opening  1008  of fiber composite support tube  102 . That is, the outside diameter  1004  is the same (less a tolerance) as the inside diameter  1006  of inner cylindrical opening  1008 . A spacer  1010  is secured around an axial outer end  1012  of housing  1002  and is dimensioned to precisely locate ends  1014  of laser fiber bundles  1126  in inner cylindrical opening  1008  to radiate weld path  1016  along a weld interface  1017  where fiber composite support tube  102  is laser welded to load introduction part  108 . An outer welding tool ring  1018  has bores  1020  for the laser fiber bundles  1126  which are arranged circumferentially so that ends  1014  of laser fiber bundles  1126  are spaced around a circumference  1026  of outer welding tool ring  1018 . The bores  1020  are spaced around circumference  1026  of outer welding tool ring  1018  so that the laser light emitted from ends  1014  of laser fiber bundles  1126  simultaneously radiates the entire weld path  1016  along the weld interface  1017 . In this regard, the laser beams exiting ends  1014  of laser fiber bundles have a circular or elliptical shape and the bores  1020  are illustratively spaced so that adjacent laser beams overlap along weld path  1016  and thus a high quality, full-area weld joint is produced. 
     As is known in the part, a variety of factors influence the laser weldability of plastic materials (thermosets and thermoplastics) that are transmissive to laser light at the wavelength being used and materials that are absorptive or partially absorptive to that laser light. With regard to fiber composite support tube  102 , factors such as the fiber and matrix materials, the volume percent of continuous reinforcing fibers and short fibers, as well as the type and even the colors (with different fillers), have an effect on the laser transparency. In laser welding, there is always a need for partially absorptive and transmissive layers in the components to be joined. Even in the case of the thermoplastic materials (that otherwise have good laser transmissivity, there are significant differences in laser transmissivity for amorphous and semi-crystalline polymer materials. Laser-transmissive thermoset materials, such as special types of epoxy resin, are known that to some extent have higher laser transmissivity rates than some thermoplastic materials, such as, e.g., PPS or PEEK. The critical factor is the wavelength A (nm) of the laser light being used for laser welding and that must transit through the transmissive part and be at least partially absorbed by the partially absorptive part at the weld interface. 
     The weight of a structure for equal strength is an important factor for lightweight structures, which are of particular interest for motor drive masses that are subject to high acceleration. Carbon fiber composites have lightweight construction parameters that are better by nearly a factor of 5 than most other materials. Even though such lightweight carbon fiber composites are known, relatively heavy energy-dissipating metal camshafts continue to be used. 
     Somewhat more expensive, but worthwhile, are flat fiber composite tube support structure surfaces with low surface roughness parameters joint layers finished by means of grinding, or another method if necessary, between the tube and the assembled components. Tight tolerances for plane parallelism of the components, for roundness (average values 1.5*10̂−3 mm), and for tube inside diameter (thickness variations of less than 0.1 mm for the fiber composite support tube outside diameter and inside diameter) are needed on account of the installation of the attached parts and the imbalance for components subjected to high acceleration. 
     In accordance with an aspect of the present disclosure, thermally stable fiber composite support tube structures are achieved in the fiber/matrix filament winding process with a winding angle of approximately 15° (see,  FIG. 2D ), with, e.g., carbon reinforcing fibers, in a thermoplastic or thermoset matrix with a thermal linear expansion approaching “0” (10̂6̂ mm*K̂−1), at an average density of 1.78 g/cm̂3) (see,  FIGS. 2A-2E ). Comparable metal camshaft support structures have substantially higher thermal linear expansion parameters—aluminum (23.1 10̂6̂ mm*K̂−1, at a density of 2.7 g/cm̂3) and steel (11.8 10̂6̂ mm*K̂−1, at a density of 7.85 g/cm̂3). Thermal linear expansion or volume expansion gives rise in fueled motors with relatively high temperatures to stresses and local deformations of the camshaft that can have a significant adverse effect on function, which speaks for fiber composite camshafts for these design and function parameters as well. 
     Controller  1104  can be or includes any of a digital processor (DSP), microprocessor, microcontroller, or other programmable device which are programmed with software implementing the above described logic. It should be understood that alternatively it is or includes other logic devices, such as a Field Programmable Gate Array (FPGA), a complex programmable logic device (CPLD), or application specific integrated circuit (ASIC). When it is stated that controller  1104  performs a function or is configured to perform a function, it should be understood that controller  1104  is configured to do so with appropriate logic (such as in software, logic devices, or a combination thereof. When it is stated that controller  1104  has logic for a function, it should be understood that such logic can include hardware, software, or a combination thereof. 
     The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.