MANUFACTURE OF FILAMENTARY COMPOSITES

Abstract: This invention relates to improvements in the industrial manufacture of composite tubes in a continuous fashion. The manufacture utilizes a segmented mandrel which proceeds as a train of endwise joined segments through a composite tube forming machine. Segments are added to and subtracted from the mandrel during manufacture of the tubes. Subtraction of mandrel segments is improved through the use of a rotating wrench which (a) grasps the leading mandrel segments through insertion of a plurality of pins into holes in the forward end of the leading segment, (b) rotates the mandrel segment and then (c) withdraws the leading segment from the segmented mandrel as the pins are removed from the holes.

Description: This invention relates to manufacture of hollow, fila­ mentary composite tubes. The resulting tubes have the fila­ mentary reinforcement selectively positioned within a thermo­ set resin matrix; they can be used, for example, to transmit torque in the drive train of motor vehicles. Filamentary composite tubes have been proposed for re­ duced weight shafts in the drive train of motor vehicles. See, for example, U.S. Patents 4,171,626; 4,236,386; 4,238,539; 4,238,540 and 4,289,557. See, also, "Development of an Advanced Composite Tail Rotor Driveshaft" by Zinberg et al presented at the 26th Annual National Forum of the American Helicopter Society, Washington, D.C., June 1970. Fabrication of composite tubes by applying fiber to a cylindrical mandrel is known. See, for example, U.S. Patents 4,248,062; 4,532,579 and 3,407,101. This invention differs from these prior art techniques in that it provides for suc­ cessive production of suitably reinforced composite tubes using a continuous tubular mandrel of joined mandrel segments. This invention relates to an improvement in the manner in which mandrel sections are disconnected from a segmented man­ drel which carries a composite tube. The method of manufactur­ ing the composite tubes (in which the improvement may be used) generally follows that of EP 83303964.7 and comprises : (A) passing a tube-shaped, segmented mandrel comprising a plurality of endwise internally joined segments lengthwise through a series of tube fabricating devices for (i) forming a resin and fiber tube around the segmented mandrel by applying at diverse angles continuous filamentary materials about the segmented mandrel and impregnating the continuous filamentary materials with hardenable resin, (ii) hardening the resin and fiber tube around the segmented mandrel after the forming; and (iii) severing adjacent the juncture between adjacently joined segments of the segmented mandrel the tubular product of the fiber and resin tube that has hardened sufficiently for the severing wherein a fresh mandrel segment continues to be added to a mandrel segment trailing in the segmented mandrel by rotating the fresh mandrel segment relative the segmented mandrel so as to thread together the segmented mandrel and the fresh mandrel segment through integral threaded members thereof; and (B) as this passage through the series continues, endwise engaging, rotating and then withdrawing from the segmented mandrel a leading segment thereof that carries a composite tube that has been severed from the tubular product in conjunction with connecting a fresh mandrel segment to the other end of the segmented mandrel as a replacement for the withdrawn leading segment; and (C) separating the composite tubes from the mandrel segments that are withdrawn from the segmented mandrel to provide the hollow composite tubular members. The improvement comprises providing the integral threaded member of the leading mandrel segment with a plurality of spaced holes which are engaged during rotation of the lead­ ing segment and withdrawal thereof from the segmented mandrel by pins of a rotating wrench that is also adapted to travel in the direction the segmented mandrel travels but at a greater speed, said pins (a) respectively engagable with lever arms which in turn are respectively pivotably mounted to the rotat­ ing wrench, (b) insertable into the holes by expansion of springs mounted between the rotating wrench and the lever arms and (c) withdrawable from the holes by a contact of the lever arms with a ring through which the rotating wrench travels after the leading segment is both unthreaded from the segmented mandrel and translated away from the segmented mandrel at a speed that is greater than that which the segmented mandrel is traveling. In the following description of this invention: "Process mandrel" means a continuous tubular mandrel formed of discrete mandrel segments joined to each other along their central longitudinal axes and around which a tubular com- posite can be formed. "Mandrel segment" means a tubular segment that can be connected to and disconnected from the process mandrel. "Composite tubular member for a light truck" means a fiber resin tubular body having continuous filaments in thermostat resin, the structural properties of which tubular body are exemplified by critical frequency not to exceed 98.23 Hz, shear torque 56,000 in-lb, buckling torque 56,000 in-lb. "Process mandrel portion" means a longitudinal portion of the process mandrel which includes any number or portion of its joined segments. "Layer" means a pair of filamentary plies, a first of which is disposed at a plus or minus first angle relative to a line parallel to an axis and the second of which is disposed at a second angle of about the same magnitude as the first angle but the negative thereof relative to such line. "Ply" means a group of filaments disposed at the substantially same angle in a geometric plane concentric with a mandrel portion which plane is normally cylindrical or substantially cylindrical in this invention. Figure 1 outlines diagrammatically a process sequence that utilizes this invention in producing composite tubes thereof. Figure 2 schematically depicts a cross section of end portions of two joined mandrel segments used in practicing this invention. The end portions are depicted with the composite tubes they carry after the cutting operation in the sequence of Figure 1. Figure 2A depicts the manner by which mandrel segments are connected at the beginning of the process sequence shown in Figure 1. Figure 3 schematically depicts in perspective an appli­ cator for applying helically disposed fibers to a process mandrel portion passing through the applicator. Figure 3A is a detail of the annular deposition ring assembly of a wheel depicted in Figure 3. Figure 4 schematically depicts in perspective an appli­ cator for applying longitudinally disposed fibers to a pro­ cess mandrel portion passing through the applicator down­ stream from the portion of Figure 3. Figure 4A is a detail of fiber application ring of an applicator in Figure 4. Figure 5 schematically depicts in perspective an appli­ cator for applying circumferentially disposed fibers to a process mandrel portion passing through the applicator down­ stream from the portion of Figure 4 or Figure 3. Figure 6 schematically depicts a cross section of a resin applicator chamber for impregnating fiber carried by a process mandrel portion passing through the chamber down­ stream from the portion of Figure 5. Figure 7 schematically depicts in perspective a bank of induction coils used to cure a resin and fiber tube carried by a process mandrel portion passing through the coils down­ stream from the portion of Figure 6. Figure 8 schematically depicts in perspective a two blade rotating cutting wheel for cutting a moving tube of hardened resin and fiber produced in accordance with this in­ vention and carried by a process mandrel portion downstream from the portion of Figure 7. Figure 9 schematically depicts in perspective an inte­ grated device that disconnects mandrel segments and subse­ quently draws a composite tube from each of the disconnected mandrel segments. The mandrel segment being disconnected is downstream of the process mandrel portion of Figure 8. Figures 9A through 9H depict through schematic drawings the sequence by which the mandrel segments are disconnected. Figure 10 is a view of a drive shaft member of this invention in elevation, including end fittings. Figure 10A is a diagramatic depiction of wall portion of the composite of Figure 10. Figure 1 shows the fabrication steps which result in composite drive shaft tubes for light trucks in accordance with this invention. The fabrication sequence is illustrated in Figure 1 as a series of steps set forth in the order in which the tubes are made. In general, endwise joined segments of a process mandrel sequentially proceed lengthwise through the tube fabricating stations identified in the fabrication sequence of Figure 1. In the final tube forming operation, however, individual man­ drel segment of the process mandrel are disconnected and a completed composite tube is extracted from each disconnected segment, the latter occuring off line from steps that pre­ cede it. Also, in the beginning of this process sequence a fresh mandrel segment is periodically joined to the rear mandrel segment of the process mandrel. The fresh mandrel segment being joined to the process mandrel may have a cylindrical metal sleeve around either or both of its ends whereby the metal sleeve becomes integrated into the com­ posite tube produced by the sequence of Figure 1. At the beginning of the tube fabricating process se­ quence depicted in Figure 1, a mandrel segment, as mentioned, is joined to the rear of a previously assembled process man­ drel at joining station A. The process mandrel comprises a number of connected segments which together have a common central longitudinal axis. (See Figure 2 for a cross-section of two joined mandrel segments.) Hand over hand clamps at station R continually pull the process mandrel away from joining station A and through the other tube fabricating stations that are downstream thereof. A moving grip jaw at station A prevents rotation of the moving process mandrel. The grip jaw holds the process man­ drel while the unconnected, fresh mandrel segment is spun into locking engagement with, and becomes the rear segment of, the process mandrel proceeding as a train of segments through downstream tube fabricating operations. An upstream ball rail mounted wrench rotates in spinning this unconnected mandrel segment into the locking relation at station A. The rotating wrench translates in a downstream direction longi­ tudinally along the upstream extension of the process mandrel central longitudinal axis in joining the new mandrel segment to the process mandrel. A bed of rollers carry the end of the process mandrel and the mandrel segment being joined thereto during the joining operation. The rollers are rotat­ able in the direction that the process mandrel proceeds. At station B dry fiber is deposited around the portion of the process mandrel that proceeds therethrough. Station B comprises a helical applicator. The helical applicator de­ posits a ply or plies of continuous filaments either at an angle between about +30° and +60°, more preferably between +35° and +55° or between about -30° and -60°, more preferably between -35° and -55° relative to a line parallel to the central longitudinal axis of the process mandrel. There are four helical applicators in the fabrication sequence of Figure 1, labeled B, D, F and H, each of which applicators deposits a ply or pair of plies at an angle within the above ranges. Helical applicators of station B, D, F and H each com­ prise a wheel having a plurality of fiber carrying spools spaced about its periphery. Filamentary tows are drawn from within the spools. The wheels of adjacent stations rotate at similar rates (but opposite each other) in spinning the continuous filaments about the process mandrel from these spools (see Figure 3 for a view of the two counter rotating wheels). As result of passage of the process mandrel through fiber deposition at these wheels, segments of the process mandrel are covered with a layer or layers of con­ tinuous filaments, as desired. For example, two layers of continuous filament can be deposited by stations B, D, F and H. In making light truck drive shaft tubes, each pair of the stations deposits a layer of filament. The layer has a +45° ply and a -45° ply where these angles are each relative to a line parallel to the central longitudinal of the process mandrel. In making these truck drive shaft tubes, each of sta­ tions B, D, F and H deposits between about .024 and .334 lbs of fiber per linear foot of the process mandrel. Each of these station B, D, F and H can utilize up to 80 rovings with yields of 113 and 1800 yrds. per lb. where the rovings each comprise E-glass filaments. Stations C, E, G, I, K, M and O in the sequence of Figure 1 provide for impregnation of the fiber deposited on the 15 process mandrel. Station C like the other of these stations (except station O) includes a resin impregnation chamber. (A cross-section of a typical resin impregnation chamber appears in Figure 6.) Station O utilizes a tubular conduit communicating with, and suspended from, a resin supply tank for direct applica­ tion of resin. The resin passes through the conduit and onto the passing fiber and resin tube proceeding from station N. The resin is worked into the passing fiber at station O by a downstream roller such as a paint roller that continuously circles the segmented mandrel. A rotating elastomer wiper blade downsteam of this roller wipes resin from the fiber. Impregnation alternatively, however, can occur by means of impregnation chamber or such direct application at any or all of stations C, E, G, I, K, M and O. For example, station M could be omitted. The process mandrel proceeds through the impregnation chamber of stations C, E, G, I, K, M and O (and the other stations) at any desired rate preferably between 1.5 and 6 feet per minute in the sequence being described. At these rates, the fiber absorbs about an equal volume of thermoset­ table resin. Fiber wetting reaches an equilibrium at about 50m percent of the total composite volume. Additional impreg­ nation stations do not significantly affect the fiber to resin ratio. Station J in the sequence of Figure 1 deposits dry fiber around the process mandrel over the impregnated fibers there­ of as it proceeds from the impregnation at station I. Sta­ tion J comprises a rotating hoop applicator wheel that ro­ tates to wind a band of continuous fiber as it spins around the moving process mandrel. (See Figure 5 for a view of this wheel). The hoop applicator applies a ply of continuous fil­ aments to the moving process mandrel at an angle between about either +75° or -75° and +88° or -88° relative to a line parallel to the central longitudinal axis of the process mandrel. For a truck drive shaft tube made using a process man­ drel having a four inch diameter and proceeding at a rate described, the hoop applicator spins around the process man­ drel at between about 18 and 72 rpm in depositing a 1 inch wide band of E-glass filaments that contains of between 113 and 1800 yrds. per lb. Station L deposits continuous graphite filaments about the fiber wound and resin impregnated process mandrel pro­ ceeding from stations J and K respectively. Station L deposits its continuous filaments about the process mandrel at an angle of about 0° relative to a line parallel to the longi­ tudinal axis of the process mandrel. Station L preferably utilizes two or more longitudinally spaced distribution rings. Rovings pass through these rings and then lay upon the previously fiber covered and resin impregnated process mandrel as it travels through the rings. (See Figure 4 for a view of the longitudinally spaced applicators of station L.) The rings each comprise an orifice which encircles the process mandrel; the rings each have holes spaced around their peripheries. The holes guide the rovings as they lay upon the fiber covered and resin impregnated process mandrel proceeding through the rings from station K or from an up­ stream ring of station L. Holes of the adjacent distribution rings are offset from each other so that the yarns or rovings are layed all around the fiber covered and resin impregnated, process mandrel. The yarns or rovings at station L have between about 12000 and 36000 filaments per roving in making the truck drive shaft composite tubes. The yarn or roving in making these drive shaft tubes comprise graphite filaments that are A-graphite. Together these filaments weigh between about 0.147 and 0.328 lbs per linear foot of the process mandrel after exit from station L. The rovings issue from the dis­ tribution rings at up to about six feet per minute in making such tubes. Station N (of the sequence of Figure 1) wraps the longi­ tudinally disposed filaments carried on the process mandrel from station L with a hoop ply of dry filaments. The hoop ply is deposited by rotating hoop wheel applicator such as discussed in reference to station J. Stations J and N each deposit the hoop ply of dry fiber at plus and minus angles of either between about +75° and +88° or between about -75° and -88° relative to a line parallel to the center longitudinal axis of the process mandrel in making the truck drive shaft composite tubes. Station O applies liquid thermosetting resin to the fi­ ber and resin covered process mandrel proceeding from station N, as described above. The fiber and resin convered process mandrel, impregnated at station O then proceeds therefrom to station P which ini­ tiates cure of the thermosettable resin, station P being shown in the sequence of Figure 1. A plurality of induction coils initiate this cure at station P. (The device carrying these induction coils is de­ picted schematically in Figure 7.) The induction coils pro­ vide a sufficient temperature increase in the resin to result ultimately in a cure thereof. Generally, in making the truck drive shaft tubes, the temperature of a mandrel segment leav­ ing station P desirably will be between about 250°F and 325°F, when using vinyl ester thermosettable resin such as Derakane from Dow Chemical Corp. Station Q of the sequence depicted in Figure 1 comprises infrared heaters. The heaters increase the outside skin temperature to 200°F. A bank of five infrared heaters are mounted around a 6 foot long cylinder. Station Q eliminates surface tack which may exist when curing thermosettable resin containing a styrene monomer in air. Some distance exists between station Q and station R. Station R of the sequence depicted in Figure 1 grips the hardened resin tube proceeding from station Q. Station R grips the composite tube sufficiently to pull it through the proceeding stations. Station R has two hand over hand grip­ ping clamps. The hand over hand gripping mechanism may be purchased from Goldsworthy Engr. of Torrence, Cal. Station S of the process sequence depicted in Figure 1 severs the hardened tube proceeding from station R. Station S comprises a pair of rotating saw blades. The saw blades cut the curing or cured tube around either side of the junc­ ture between two joined mandrel segments of the process man­ drel. The blades rotate about the process mandrel to sever a composite tube completely from the upstream portion thereof. (See Figure 8 for a view of the cutter. The short cylindri­ cal section of composite tube formed between the blades by the cutting action thereof is removed at station U during the pulling of the mandrel segments from their respective compos­ ite tubes.) The blades translate along a line parallel to the central longitudinal axis of the process mandrel in severing the cured tube as it proceeds through station S. After the tube is severed, the blades together translate upstream to their starting position. Station T of the process sequence identified in Figure 1 disconnects the mandrel segment carrying a severed tube from the rest of the process mandrel. A clamping jaw at station T prevents rotation of the process mandrel by gripping an up­ stream portion thereof around the cured composite tube that it carries. The downstream joined mandrel segment is then disconnected from the rest of the process mandrel by a rotat­ able wrench at station T. The rotatable wrench engages the leading mandrel segment (carrying the composite tube se­ vered at station S) and spins it free of the moving upstream train of joined mandrel segments. (See Figure 9 for schema­ tic view of the mandrel segment disconnecting and tube extracting device combination.) The disconnected mandrel segment carrying the cured com­ posite tube proceeds to station U of the process sequence de­ picted in Figure 1. Station U is at the side of the main machine axis. The composite tube is extracted from the dis­ connected mandrel segment in an extraction die. The discon­ nected mandrel segment is pulled through the extraction die stripping the cured composite tube. The disconnected mandrel segment proceeding from the extraction die, now free of the cured composite tube, then proceeds to station V which con­ tains a mold release bath. The freed mandrel segment is still at elevated temperature (e.g. 130°F. ) as it enters this mold release bath. The elevated temperature helps bake the mold release of the extracted mandrel segment. The cured composite tubular member, when freed of the disconnected mandrel segment, can be rolled to a storage cart. The mandrel segment, when freed of the cured composite tubular member can be returned to station A for further use. The composite tubular member when used in a truck drive shaft can incorporate a metal sleeve at each end. The metal sleeve can be adhesively bonded within, or on the outside of, the tube. Alternately, each mandrel segment can carry metal sleeves at its ends through the fabrication sequence of Figure 1. These sleeves act as parts of the mandrel segment in that the composite tube is formed about them. A riveting operation can rivet the sleeves in this latter case to the composite tubular member after completion of tube manufacture (i.e. after station V). The method of this invention has been described in a tube fabrication sequence suited for making truck drive shaft composite tubes. As, however, may be apparent, such sequence is but illustrative of the many sequences that can be used in making these or other composite tubular members using princi­ ples of this invention. Another sequence is A, B, C, D, E, J, K, L, M, N, P, Q, R, S, T, U and V; different combinations of fiber yield and numbers of rovings can also be employed in any of these sequences. Figures 2 through 9 illustrate equipment identified in previous description of the process sequence of Figure 1. Figure 2 is a cross-section of the joined ends of two cylindrical mandrel segments 10, 12 that are used in making composite drive shaft tubes for certain light trucks in con­ nection with the process sequence of Figure 1. Joined man­ drel segments 10, 12 have cylindrical steel sleeves 14, 16 which slip over their respective ends. Plastic sleeve 18 fits cylindrically about and between adjoining end portions of steel sleeves 14, 16 and between segments 10, 12. The opposite ends (not shown) of each mandrel segments 10, 12 are configured to permit their respective joining with other mandrel segments. Mandrel segment male member 20 is bolted to mandrel seg­ ment 12 and has integral male acme threads 22 for connecting mandrel segment 12 to mandrel segment 10. Mandrel segment 10 has socket 24 with threads 26 for receipt of threads 22 in locking relation. Mandrel segment 10 joins to mandrel seg­ ment 12 with relative rotation between them of between about 1 and 2 revolutions. The unthreaded portion of male member 20 guides the approach and retreat of mandrel segment 12 to and from mandrel segment 10. Mandrel segments 10, 12 depicted in Figure 2 have pro­ ceeded through tube cutting station S in the sequence of Fig­ ure 1. Circumferential spaces 28, 30 depict where station S has severed the composite tube carried by the mandrel seg­ ments 10, 12. Mandrel segment 12 leads mandrel segment 10 in this sequence in the direction shown in Figure 2. Accord­ ingly, mandrel segments 10, 12 carry downstream cured compos­ ite tube 32, upstream composite tube 34 and intermediate com­ posite tube 36. Downstream composite tube 32 becomes, with sleeve 16 and a sleeve (not shown) at the other end of man­ drel segment 12, a drive shaft member of this invention after it is separated from mandrel segment 12. Upstream composite tube 34 becomes another drive shaft member with sleeve 14 (and other sleeve) once tube 34 is severed and the severed tube separated from the mandrel segment 10. Intermediate compos­ ite tube 36 remains with mandrel segment 10 after discon­ nection of mandrel segment 12 therefrom until stripping of tube 34 from mandrel segment 10 at station U. After mandrel segment 12 has been unthreaded and removed from the rest of the process mandrel at Station T, previously discussed, mandrel segment 10 becomes the leading mandrel segment of the process mandrel. Three holes in the end of socket 25 permit grasping of segment 10, as is discussed in connection with Figures 9A through 9E, for unthreading segment 10 and disconnecting it from the rest of the process mandrel. One of these holes is shown as 27 in Figure 2. Figure 2A illustrates the device that connects trailing mandrel segments to the end of the process mandrel. This connection is illustrated in the three views of Figure 2A. The left drawing in Figure 2A shows rotating wrench 11 which is mounted to slide to the right on rail 13. Mandrel segment 10 is shown in the left drawing of Figure 2A as not yet con­ nected to the process mandrel. Mandrel segment 10 is first placed as a fresh mandrel segment on a bed of rollers (not shown). Rotating wrench 11 then is caused to slide forward rail 13 to engage hex hed 21 of male member 20. Once socket 15 engages hex head 21, motor 17 of wrench 11 is activated and causes socket 15 to rotate mandrel 10 to thread it to the process mandrel as depicted in the center drawing of Figure 2A. Once mandrel sement 10 is connected, wrench 11 indexes to its starting position. Intermediate composite tube 36 has been cut out at tube cutting station S. Plastic sleeve 18 serves to provide tolerance in the depth of this cut. Plastic sleeve 18 may be spaced a small amount from around the ends of mandrel segments 10, 12 to aid in permitting unthreading of the mandrel segments without excessive drag. To accomplish this spacing as well as seal off the inside of mandrels 10, 12 from resin seepage, sleeve 18 may be designed with a circum­ ferential rib around each of its ends 23, 27, such rib pro­ jecting radially inward around the inside of sleeve 18. Figure 3 depicts an apparatus which is depositing fiber about process mandrel portion 38 as it passes through wheels 40, 42 carried by respective fixed mounts 44 and 46. Each of wheels 40, 42 has a plurality of spools (a few pairs of which are depicted as respectively, 48, 50 and 52, 54) of continu­ ous filament fixed around their respective faces 56, 58 and 60, 62. The wheels counter rotate, such as in the directions shown in Figure 3, in depositing continuous filaments about process mandrel portion 38 as discussed above in connection with stations B and D and F and H of Figure 1. Resin impregnation chamber 64 (station C and station E) is between wheels 40, 42 and is seen in greater detail in Figure 6 as device 130. Continuous filaments from spools 48, 50 and 52, 54 pass to respective annular deposition ring assemblies 66, 68 which rotate with their respective wheels 40, 42. This fiber pas­ ses through holes in the annular ring assemblies 66, 68 for orientation onto process mandrel portion 38. The speed at which wheels 40, 42 and consequently rings assemblies 66, 68 rotate relative to the axial translation of process mandrel portion 38 through these ring assemblies determines the angle at which the fibres deposit on process mandrel portion 38. Figure 3A is a detail of ring assembly 66 of Figure 3. Continuous filament 70 feeds from plastic tubes such as 72 and through holes such as 74, 76 respectively in orienting plates 78, 80. Tubes serve to protect filaments 70 and enable ready threading thereof from the spools (e.g. 48, 50) of filaments. Figures 4 and 4A schematically illustrate longitudinal fiber applicator 82 which is depositing continuous filaments longitudinally (relative the center longitudinal axis of pro­ cess mandrel portion 84) along the process mandrel. Spaced fiber disposition rings 86, 88, 90, 92 permit issuance of continuous fiber passing from remote spools of creels (not shown) through their respective offset holes 94, 96, 98, and 100. Holes 94, 96, 98 and 100 are respectively spaced about segmented mandrel portion 84 in these rings 86, 88, 90, 92. There are about 51 holes in each of the spaced disposition rings 86, 88, 90, 92. Each individual hole in holes 94, 96, 98 and 100 receives up to about 36000 or more filaments. Conduits 102, 104, 106, 108 lead from the creels to respec­ tive holes 94, 96, 98 and 100 to maintain alignment of the roving or yarn passing to each of these holes. The roving or yarn issue from these holes to process mandrel portion 84 without any surrounding conduit. In making the light truck composite tubes, there are four rings longitudinally spaced between about 12 and 18 inches from each other. These rings deposit continuous fila­ ments at a zero degree angle relative to a line parallel to the central longitudinal axis of the process mandrel. Figure 5 schematically illustrates device 110 that is depositing fiber circumferentially about process mandrel por­ tion 112. Device 110 serves the function of providing hoop windings in the fabrication sequence of Figure 1 and rotatably mounts to fixed mount 128. Device 110 has wheels 114, 116 which rotate in tandem. Wheels 114, 116 carry spools 118, 120 about their respective outer face peripheries 122, 124. Continuous filament feeds from these spools to a rotating eyelet (not shown) between wheels 114, 116 for depositing the filaments onto mandrel portion 112. The eyelet rotates about process mandrel portion 112 with wheels 114, 116 at a rate, relative axial translation of process mandrel portion 112, which permits a desired angle of fiber disposition. Figure 6 is a diagrammatic cross-section of resin appli­ cator device 130 which is serving to impregnate fiber as dis­ cussed in connection with stations C, E, G, I, K and M the fabrication sequence of Figure 1. Applicator device 130 comprises resin chamber 132. Fibrous tube 134 carried by process mandrel portion 136 pas- ses through resin chamber 132 which is circumferentially sealed at its mandrel entry and exit orifices by rubber ring seals 138, 140, respectively. Resin chamber 132 is filled continuously with resin 142 at inlet 144 with liquid resin at a pressure of between about 4 ft. and 8 ft. resin head. Out- let 146 can be used as overflow, if desired. The resin can be any hardenable liquid resin and preferably is vinyl ester thermosettable resin (e.g. Derakane, from Dow Chemical Co., Midland, Michigan) formulated with suitable peroxide catalyst and maintained at between about 60° and 90°F. in chamber 132. The use of vinyl ester resin with peroxide catalyst gives thermosettable resins with appropriate pot lives (e.g. between about 8 and 12 hours) for shift operations. Figure 7 is a schematic illustration of induction heater device 148 which is serving the function of curing thermoset­ table resin as described in reference the tube fabrication sequence in Figure 1. Curing device 148 is mounted on fixed mounts 154 and has a plurality of induction coils 150 spaced about resin and fiber covered process mandrel portion 152 passing therethrough. The heating by induction coils 150 is calibrated at various mandrel speeds to permit automatic operation of the tube fabrication. Figure 8 is a schematic illustration of tube cutting de­ vice 156 which is serving to sever hardened tube 158 adjacent the juncture between joined mandrel segments of the process mandrel as discussed in conjunction with the process steps in Figure 1. Cutting device 156 has rotating saw blades 164, 166 mounted to rotating disc 168. Rotating disc 168 rotates ro­ tating saw blades 164, 166 about axis 170 while at the same time translating longitudinally along this axis 170 (in the direction shown) at the same rate as the joined mandrel seg­ ments. Saw blades 164, 166 rotate around their own axes and this axis 170 in severing a cylindrical section (e.g. tube 36, Figure 2) from composite tube 158 on either side of the juncture between the adjacently joined mandrel segments. The plastic sleeve (see Figure 2) underneath the composite tube 158 provides tolerance for the cutting of blades 164, 166. Hydraulically activated clamp 160 grips composite tube 158 and prevents rotation thereof while translating with the 35 moving process mandrel. Clamp 160 moves in tandem with blades 164, 166 along axis 170 while they cut tube 158 and then indexes with them back to the starting position. Figure 9 illustrates mandrel release and extraction de­ vice 172 which has functions as discussed in connection with the fabrication sequence in Figure 1. In disconnecting mandrel segments, wrench 174 (shown in Figures 9 and 9A receives the perforated plug end 175 of the leading mandrel segment 173 (carrying composite tube 171 and sleeve 169) of the process mandrel. Before plug end 175 con­ tacts wrench 174, however, plug end 175 is sensed by light sensor A. Sensor A being carried by wrench 174 and, having found plug end 175, causes clamp 176 to grasp around the composite tube 178, composite tube 178 being the tube carried by the mandrel segment trailing next to mandrel segment 173. Clamping around this trailing mandrel segment by clamp 176 isolates the leading mandrel segment from the remainder of the process mandrel and permits its unthreading therefrom without rotation of the process mandrel. Clamp 176 is drawn along with the trailing mandrel segment (i.e., the mandrel segment following leading mandrel segment 173) as long as clamp 176 is clamped to this trailing mandrel segment. After the leading mandrel segment is unthreaded from the process mandrel, clamp 176 releases and travels back to home so as to be ready for subsequent clamp­ ing around the mandrel segment trailing the previously clamped mandrel segment. Figures 9A through 9G further depict the sequence that is followed in sequentially disconnecting mandrel segments from the process mandrel. This sequence, commencing when plug end 175 passes sensor A, as previously described, ends with leading mandrel segment 173 (carrying composite tube 171) being pushed offline from the travel of the process mandrel to the mandrel extraction station U shown in the front of the mandrel disconnect system of Figure 9. As is seen in Figure 9A through 9E, wrench 174 has spring loaded pins 220, 222 and a third pin 224 (Figure 9C) spaced 120° apart from each other around wrench 174. These pins 220, 222, 224 each depend into cavity 230 of wrench 174 prior to engagement with the process mandrel and have a bevel edge such as 226 (see, for example, Figure 9D). When extended, springs such as spring 228 respectively cause these pins to be held in cavity 230 of wrench 174. Each of the springs 228, 228' and a third spring (not shown) are mounted to wrench 174 and to respective lever arms 227, 227' and 227". Lever arms 227, 227' and 227" are pivotly mounted in respective lever housings 225, 225' and 225". Lever arms 227, 227' and 227" each have a downstream end that is tapered in a downstream direction and a forward end adapted to receive a post for moving the respective pins 220, 222 and 224 in and out of cavity 230. Figures 9F, 9G and 9H illustrate the operation of these lever arms and springs by way of schematic views of lever arm 227, lever housing 225, pin 220 and other associated elements for grasping and releasing mandrel segments. As can be seen in these Figures 9F, 9G and 9H, lever arm 227 has forward (or upstream) cavity 229 in which post 231 slideably fits between spaced guide bars 233. When spring 228 is extended, the upper lip 239 of cavity 229 engages post 231. Post 231, rigidly mounted to the side of pin 220, is forced downward thereby causing post 231 to insert pin 220 in cavity 230. When wrench 174 proceeds downstrean so that the downstrean end of lever arm 227 engages retraction ring D, as shown in Figure 9G, spring 228 is forced to contract as lever arm 227 pivots around pivot post 223 in lever housing 225. The forward end of lever arm 227 is thereby caused to rotate upwards and the bottom lip 241 of cavity 229 engages post 231. Post 231 thus moves upward as lip 241 rotates upward around pivot post 223. This upward movement of post 231 causes pin 220 to withdraw from cavity 230 thereby disengaging pin 220 of wrench 174 from the hole 234 in the male member leading the forward mandrel segment. Lever arms 227' and 227" and respectively associated spring 228' and a third spring (not shown) operate in similar fashion so that pins 220, 222 and 224 are inserted and withdrawn from cavity 230 simultaneously in grasping and releasing the forward end of the leading mandrel segment. Returning once again to Figures 9A through 9E, it can be seen that as plug end 175 enters cavity 230, the pins 220, 222, 224 are temporarily forced out of cavity 230 to allow entry of plug end 175. Slow rotation of wrench 174 (wrench 174 is set to rotate slowly prior to activation by Sensor B) causes the pins 220, 222, 224 find respective holes 232, 234, 236 in plug end 175; and then the spring 228 and other springs respectively force the pins 220, 222, 224 into these holes 232, 234, 236 as is depicted in Figure 9B. Sensor B, mounted on wrench 174, then finds the forward lip 238 of the leading mandrel segment 173 and starts the motor (not shown) carried on the downstream end of wrench 174 to rotate rapidly. The rapid rotation of wrench 174 begins unthreading the mandrel segment 173 form the rest of the process mandrel. (If wrench 174 disengages from the mandrel before it has been properly disengaged by unlocking ring D (Figure 9D), wrench 174 will again drive home or upstream until it again engages the pins 220, 222, 224 in the holes 232, 234, 236.) When wrench 174 reaches sensor C, however, wrench 174 is stopped from driving upstream and is hydraulically caused to translate downstream at a rate greater than the rate the process mandrel is traveling. The downstream travel of wrench 174 pulls mandrel segment 173, now unthreaded, away from the remainder of the process mandrel. When unlocking ring D (Figures 9D and E) is reached, a limit switch (not shown) is also activated which unlocks clamp 176. Clamp 176 then indexes to its starting position. This limit switch also starts a time delay switch. At the end of the time delay of this delay switch, flipper arms 240 rotate as is shown in Figure 9E to take the leading mandrel segment 173 along with composite tube 171, sleeve 169 and trailing sleeve (not shown) offline for mandrel extraction. During the period of time delay before flipper arms 240 activate, wrench 174 passes through unlocking ring D. Un­ locking ring D forces the springs, e.g., spring 228, down with the result that pins 220, 222 and 224 are withdrawn from holes 232, 234 and 236. Spring clip F, spring mounted adjacent to wrench 174 on tube 219, was initially compressed by travel of the process mandrel inserting plug end 175 into cavity 230 of wrench 174. When mandrel segment 173 is released from wrench 174 by withdrawal of pins 220, 222 and 224, spring clip F forces mandrel segment 173 upstream causing plug end 175 to withdraw from cavity 230 of wrench 174. Flipper arms 240 are then activated because the time delay, as previously discussed, has expired. Limit switch E on conveyor 242 senses the arrival of mandrel 173. This limit switch E causes the wrench 174 to reverse direction and drive upstream to its starting position. The sequence depicted in Figures 9A through 9E shows sleeve 169 extending beyond the end of composite tube 171. Prior to such sequence, the intermediate tubular composite section (such as 36 shown in Figure 2) has been carried on the trailing end of mandrel segment 173. Alternatively, however, in view of the amount by which plug end 175 extends beyond the end of mandrel segment 173 and the nature of the attachment of wrench 174 to this plug end, the tubular section between cut composite tubes may also be on the leading end of the leading mandrel section during disconnection. After the leading mandrel segment is disconnected, the forward end of the mandrel segment trailing this disconnected segment comes into contact with a cutter activation device (not shown). The cutter activation device comprises a cutter arm that positions itself in the path of the process mandrel at the head of the leading mandrel segment. The cutter arm is connected to the carriage that carries the saw blades such that contact with this arm by the leading mandrel segment of the process mandrel draws the saw carraige along with the process mandrel. In addition, contact with the arm starts the saw blade to move radially inward for cutting the composite tube carried by the process mandrel. Use of this arm for cutter activation insures that that the saw blades acti­ vate in exact relationship to the end of the process mandrel thereby insuring that the composite tubes are cut precisely between joined mandrel segments. The cutter arm is on a switch (not shown) that is activated after flipper arms 240 return to their starting position (i.e., after flipping the lead mandrel segment offline). Extractor 184 pulls mandrel segment 186 out of tube 188. Disconnected mandrel segments, when being drawn from composite tubes, are simultaneously drawn through mold release bath 190. The composite tube 188 once freed can then be sent to storage, or alternatively, sent to a riveting operation which rivets the metal sleeves to the composite tubular members thereby completing manufacture of the drive shaft member. Figure 10 depicts composite tube drive shaft member 200 which is for use in the drive train of a vehicle classified as a light truck. The drive shaft tube member 200 has been made using the techniques discussed in connection with the fabrication sequency of Figure 1. Composite tube 202 carries hollow metal sleeves 204, 206 inside its flared ends 208, 210. Hollow metal sleeves 204, 206 are generally cylindrical in configuration; each of sleeves 204, 206, however, has a wall that thins toward the center of composite tube 202 with an inner diameter that is constant. Because of this thinning of the wall diameter of the sleeves 204, 206, there is about a 1° taper to each sleeve. Rivets 212, 214 respectively pass through and around flared ends 208, 210 of composite tube 202 and through sleeves 204, 206 in fixing these sleeves 204, 206 in composite tube 202. Rivets 212, 214 are added after the tube fabrication sequence of Figure 1 as a separate operation. Alternatively sleeves such as sleeves 208, 210 can be ad­ hesively bonded to a composite tube such as tube 202 after fabrication thereof. Rivets 212, 214 each are disposed circumferentially about composite tube 202 in a pair of circles. Each circle of rivets has seven rivets, making 28 rivets per drive shaft. Figure 10A diagramatically depicts a wall portion of tube member 200 of Figure 10 that includes a portion of 15 sleeve 206. The wall depicted in Figure 10A typifies a wall of a composite tube that can be made in accordance with this invention; the filament in this wall is positioned for trans­ mitting torque in the drive train of a motor vehicle that would be classified as a light truck. The wall depicted in Figure 10A has distinct, but inte­ grated zones of continuous filament and resin. Zone A is composed of four subzones A1, A2, A3 and A4. Each of sub­ zones A1, A2, A3 and A4 is a ply of E-glass filament in ther­ moset resin matrix. The angle at which the continuous glass filaments are helically disposed in these subzones is nomi­ nally +45° or -45°, e.g., ±30, relative to a line parallel to central longitudinal axis 216 of the composite tube 202 of Figure 10. The filaments in zone A were deposited at stations B, D, F and H in the sequence of Figure 1. Zone B comprises subzones B1 and B2 spaced on either side of zone C in Figure 10A. Each of subzones B1 and B2 has a ply of substantially circumferentially disposed continuous glass filaments. These filaments in zone B are E-glass and disposed desirably at an angle with an absolute value of between about 82° and 88°, normally between about 84° and 86°, relative to a line parallel to central longitudinal axis 216 of tube 202. The filaments in zone B were deposited at stations J and N in the sequence of Figure 1. Zone C of Figure 10A comprises carbon or graphite fiber at an angle of zero degrees (±3°) relative to a line parallel to central longitudinal axis 216 of tube 202. These carbon or graphite fibers are 36,000 filament. The filaments in zone C were deposited at station L in the sequence of Figure 1. The filaments in composite tube 202 comprise between about 50% and 60% by volume of tube 202, the remainder being a crosslinked vinyl ester resin. In an alternative embodiment, zone B has but a single ply of filament and this single ply is around the outside of zone C. In a variation of this embodiment, zone A has but a single layer of filament, i.e. zones A1 and A2. In still other applications of this invention, the filaments can be positioned during manufacture to suit requirements of such other applications.

Claims: 1. In method of manufacturing hollow composite tubular members which comprises (A) passing a tube-shaped, segmented mandrel comprising a plurality of endwise internally joined segments lengthwise through a series of tube fabricating devices for (i) forming a resin and fiber tube around said segmented mandrel by applying at diverse angles continuous filamentary materials about said segmented mandrel and impregnating said continuous filamentary materials with hardenable resin, (ii) hardening said resin and fiber tube around said segmented mandrel after said forming; and (iii) severing adjacent the juncture between adjacently joined segments of said segmented mandrel the tubular product of said fiber and resin tube that has hardened sufficiently for said severing wherein a fresh mandrel segment continues to be added to a mandrel segment trailing in said segmented mandrel by rotating said fresh mandrel segment relative said segmented mandrel so as to thread together said segmented mandrel and said fresh mandrel segment through integral threaded members thereof; and (B) as this passage through said series continues, endwise engaging, rotating and then withdrawing from said segmented mandrel a leading segment thereof that carries a composite tube that has been severed from said tubular product in conjunction with connecting a fresh mandrel segment to the other end of said segmented mandrel as a replacement for said withdrawn leading segment; and (C) separating said composite tubes from the mandrel segments that are withdrawn from said segmented mandrel to provide said hollow composite tubular members; the improvement which comprises providing said integral threaded member of said leading mandrel segment with a plurality of spaced holes which are engaged during rotation of said leading segment and withdrawal thereof from said segmented mandrel by pins of a rotating wrench that is also adapted to travel in the direction said segmented mandrel travels but at a greater speed, said pins (a) respectively engagable with lever arms which in turn are respectively pivotably mounted to said rotating wrench, (b) insertable into said holes by expansion of springs mounted between said rotating wrench and said lever arms and (c) withdrawable from said holes by a contact of said lever arms with a ring through which said rotating wrench travels after said leading segment is both unthreaded from said segmented mandrel and translated away from said segmented mandrel at a speed that is greater than that which said segmented mandrel is traveling. 2. The method in accordnce with Claim 1, wherein said lever arms respectively carry a socket into which an integral arm of each said pin fits. 3. In method of manufacturing hollow composite tube members which comprises (A) pulling a tube-shaped, segmented mandrel comprising a plurality of endwise internally threaded together segments lengthwise through a series of tube fabricating devices for (i) forming a resin and fiber tube comprising continuous filamentary reinforcements about said segmented mandrel passing therethrough and impregnating said continuous filamentary reinforcements with hardenable resin and (ii) hardening said resin and fiber tube around said segmented mandrel after said forming wherein a fresh mandrel segment having an engagable integral threaded female member continues to be added to a mandrel segment trailing in said segmented mandrel by rotating said fresh mandrel segment relative said segmented mandrel so as to thread together an integral male member thereof and said threaded female member in locking relation; (B) pushing said segmented mandrel which carries a tubular product resulting from said hardening lengthwise through another series of devices for (iii) severing said tubular product adjacent the juncture between adjacently joined segments of said segmented mandrel and (iv) endwise engaging said female member of, rotating and then withdrawing from said segmented mandrel a leading segment thereof that carries a composite tube that has been severed from said tubular product in conjunction with threading said fresh mandrel segment to the other end of said segmented mandrel as a replacement for said withdrawn leading segment; and (C) separating the composite tubes from said mandrel segments that are withdrawn from said segmented mandrel to provide said hollow composite tube members, the improvement which comprises providing a rotating wrench for grasping, rotating and withdrawing said leading segment, said rotating wrench comprising (a) spring-loaded pins which are adapted fit into holes spaced around said female member while said rotating wrench spins in a first direction, (b) means for rotating said wrench in a second, opposite to said first direction, (c) means for withdrawing said leading mandrel segment from said segmented mandrel after unthreading said leading mandrel segment, said means for withdrawing causing said leading mandrel segment to translate in the direction of travel of said segmented mandrel at a speed greater than said segmented mandrel travels and (d) means for cooperative withdrawal of said pins from said holes, said means for cooperative withdrawal comprising a level arm adapted to compress the springs of said spring loaded pins in cooperation with a ring through which said leading mandrel segment is translated by said means for withdrawing said leading mandrel segment.

Inventors: GILL, DEE RICHARD, MARKS, REX BLAINE
Applicants: HERCULES INCORPORATED
Application year: 1986
Main classification: B29D23
IPC codes: F16F9, B29C69, B32B1, B29C70, B29C53, B29D23, B29C33