US3555614A

US3555614A - Tube forming apparatus

Info

Publication number: US3555614A
Application number: US801888*A
Authority: US
Inventors: Arthur J Wiltshire
Original assignee: Structural Fibers Inc
Current assignee: Structural Fibers Inc
Priority date: 1968-11-18
Filing date: 1968-11-18
Publication date: 1971-01-19
Anticipated expiration: 1988-01-19

Abstract

A TUBE FORMING APPARATUS IS DISCLOSED WHICH INCLUDES A ROTATABLE MOLDING CHAMBER AND MEANS FOR FEEDING A CONTINUOUS FIBER FILAMENT INTO THE MOLDING CHAMBER AT A PREDETERMINED FEED RATE WHICH IS LESS THAN THE SURFACE SPEED OF THE MOLDING CHAMBER TO DEPOSIT THE FIBER FILAMENT ONTO THE INNER SURFACE OF THE MOLDING CHAMBER IN A PREDETERMINED PATTERN. A CONVEYOR MEANS DISTRIBUTES CHOPPED FIBERS OVER THE COILED CONTINUOUS FILAMENT, AND A THERMOSETTING RESIN IS SUPPLIED TO THE MOLDING CHAMBER TO IMPREGNATE THE CONTINUOUS FIBER FILAMENT AND THE CHOPPED FIBERS.

Description

,1971 A.J.WILTSHIRE 3,555,614

TUBE FORMING APPARATUS Original Filed June 22. 1964 9 Sheets-Sheet 1 I s A g A R 2 8 0 m 53 Q E S i .b A 8 E E g i 3 l J INVENTOR.

a ARTHUR J. WILTSHIRE 3 Q BY W m W ATTORNEYS Jan- 1971 A. J. WILTSHIRE 55,614

TUBE FORMING APPARATUS I Original Filed June 22 1964 9 Sheets-Sheet :5

INVENTOR.

ARTHUR J. WILTSHIRE Jan. 19-, 1971 A. J. WILTSHIRE 3,555,614

TUBE FORMING APPARATUS I Original File d June 22, 1.964 9 Sheets-Sheet 4 ig. 2b

INVENTOR.

ARTHUR J. WILTSJIIRE BYWWIJWQ v L W ATTORNEYS Jan. 19, 1971 A. J. WILTSHIRE 3,555,614

TUBE FORMING APPARATUS Original Filed June 22 1964 9 Sheets-Sheet 5 \Q INVENTOR. ARTHUR J. WILTSHIRE w ATTORNEYS A. J. WILTSHIRE 3,555,614

TUBE FORMING APPARATUS 9 Sheets-Sheet 6 I l I INVENTOR. ARTHUR J WILTSHIRE Y )I-Cm A 3%;

7 1 {.aml/ V d is -J d ATTORNEYS HHHIIIII I nD P Jan. 19, 1971 Original Filed June 22, 1964 1971 A. J. WILTSHIRE 3,555,614

TUBE FORMING APPARATUS Original Filed June 22 1964 9 Sheets-Sheet '7 Jan. 19; 1971 4 A. J. w lRE 3,555,514

TUBE FORMING APPARATUS Original Filed June 22v L964 9 Sheets-Sheet 8 III/II I/ I 64 i 111/] FL Fig. 7

INVENTOR.

ARTHUR J. WILTSHIRE ATTORNEYS Original Filed June 22 1964 Jan. 19, 1971 A. J. WILTSHIRE r 3,555,614

TUBE FORMING APPARATUS 9 Sheets-Sheet 9 Fig- 9 INVENTOR.

ARTHUR J. WILTSHIRE United States Patent 3,555,614 TUBE FORMING APPARATUS Arthur J. Wiltshire, Cleveland, Ohio, assignor to Structural Fibers, Inc., Chardon, Ohio, a corporation of Ohio Original application June 22, 1964, Ser. No. 376,918.

Divided and this application Nov. 18, 1968, Ser.

Int. Cl. B28]: 21/32 US. Cl. 18-26 8 Claims ABSTRACT OF THE DISCLOSURE This application is a divisional application of US. patent application Ser. No. 376,918, filed June 22, 1964, and now abandoned.

This invention relates generally to the manufacture of fiber-reinforced, seamless articles and, more particularly, pertains to the manufacture of fiber-reinforced plastic tubes which are fabricated by laying up a continuous fiber filament and randomly oriented chopped fibers within a hollow, cylindrical mold, impregnating the chopped fibers and continuous filament with a thermosetting resin, and heating the resin-impregnated, laid-up fibers and filament to set the resin.

The invention constitutes an improvement in the methods and articles produced in accordance with the teachings set forth in my copending application Ser. No. 278,382.

One of the commercial applications of the invention described and claimed in the aforementioned application is in the manufacture of domestic water softener tanks and similar large, Watertight and chemically resistant, hollow objects. In general, the preferred tank structures are elongated cylinders having outwardly convex end walls, at least one of the end walls having a central opening therein for communication with the interior of the tank.

According to the methods described in the above-mentioned application, the hollow tanks are successfully and economically produced by providing a fiber-reinforced, molded plastic shell and by winding a continuous fiber filament on the cylindrical sidewall of the shell at approximately 90 to the axis of the shell.

The molded shell is produced by laying up fiber matting in the approximate form of the desired object and encasing this form within a rigid, open-end, cylindrical mold casing. An expandable bag or envelope, or other fluidexpandable membrane, which defines the shape of the finished article, is positioned within the laid-up form in the mold, and preformed fiber end Wall caps are telescoped into each end of the laid-up form. The external cylindrical mold casing is closed by clamping to the ends thereof rigid casing caps which shape the end walls of the tank formed therein. With the mold and fiber preforms thus assembled, the matting is placed under a suitable moderate pressure by expanding the bag to hold the fiber matting in place against the mold, and then the fiber matting is partially permeated with a thermosetting resin or the like. The bag is subsequently expanded by further inflation to progressively compress the fiber matting in such a manner as to distribute the resin throughout the matting and achieve the desired results of pressure-molding, while, at the same time, avoiding migration of the fibers and destruction of the laid-up fiber mats. After the fiber body of the article has been thus impregnated and shaped within the mold, and while the shape is maintained by pressure from the bag, the casing of the mold is usually subjected to heat in order to accelerate setting of the resin. When the resin has set, the bag is opened to the atmosphere and is thereby collapsed. The upper and lower casing caps are then removed from the mold casing, the bag is removed through a hole in the upper end of the formed structure, and the finished molded article is then slid longitudinally from the mold casing.

As distinguished from prior art tanks generally produced in accordance with this pressure-molding technique, the molded shell, according to my copending application, is designed to withstand only the longitudinal stresses that result from a predetermined internal pressure. The shell that is initially provided in accordance with the teachings of my above-mentioned application, therefore, has a wall thickened that is approximately one-half the thickness of the prior art tanks. The resin-impregnated filaments that are wound about this shell are intended to support substantially all of the hoop stresses that the cylindrical wall is to support. This procedure produces a finished seamless tank having a cylindrical wall in which all of the longitudinal stresses are carried by the shell and substantially all of the circumferential stresses are carried by the circumferential winding. The resulting tank wall is approxi mately fifty percent lighter than a tank wall of equal hoop strength (the critical consideration) formed by impreg nated glass fiber matting alone.

The production of tanks in accordance with my abovementioned application, however, involves two separate manufacturing steps, i.e., molding the shell and winding continuous filaments on the molded shell. The formation of the shelf itself, furthermore, involves the laborious and time-consuming steps of laying up a fibrous preform within a mold casing, positioning an expandable bag in the preform, and injecting the laid-up fiber form with a thermosetting resin, as is set forth above. This plastic impregnated fiber form, furthermore, must be hardened prior to the filament winding operation so that the shell acts as a rigid mandrel during the winding step.

The present invention has for its main objective the provision of improvements in the methods disclosed in the above application to produce seamless tanks having improved strength and Weight characteristics and to produce the cylindrical sidewall of the tanks by a centrifugal molding technique.

A more specific object of the present invention is to provide an improved method of fabricating a tank and improved apparatus for carrying out the method that eliminate circumferential winding techniques and the use of fiber preforms.

In general, these objectives are attained by laying down a continuous fiber filament within a rotating, cylindrical mold and, simultaneously, impregnating the filament with a suitable thermosetting resin. After the filament is laid on the cylindrical sidewall of the mold in any desired pattern, randomly oriented, chopped fibers and a suitable thermosetting resin are introduced into the mold and onto the laid-up, resin-impregnated continuous filament. The rotating mold is then heated to fully cure the resin and produce a resin-impregnated tank sidewall having a continuous filament outer layer and a randomly oriented fiber inner layer. Alternatively, the continuous filament and chopped fibers may be laid up in the mold prior to the introduction of resin.

Other objects and advantages of the invention will become apparent from the following detailed description and the accompanying drawings.

In the drawings:

FIG. 1a is a side elevation of a portion of the machine in accordance with the present invention;

FIG. 1b is a side elevation of another portion of the machine according to this invention;

FIG. 2a is a top plan view of the portion of the machine shown in FIG. 1a;

FIG. 2b is a top plan view of the portion of the machine shown in FIG. lb;

FIG. 3 is a sectional view, the plane of the section being indicated by the line 33 in FIG. 1a;

FIG. 4 is a sectional view, the plane of the section being indicated by the line 44 in FIG. 2a but showing the filament feeding device in an operating position within the mold;

FIG. 5 is a sectional view of the machine, the plane of the section being indicated by the line 5-5 in FIG. 4;

FIG. 9 is a sectional view of a finished pressure vessel produced according to the present invention.

Referring now to the drawings, and particularly to FIGS. 1a and 1b, a tube molding machine is illustrated. The machine 20 includes a filament and resin-feeding portion 21, a mold portion 22, and a chopped fiber and resin-feeding portion 23. The

portions

21, 22, and 23 are mounted on a base frame 24.

The filament and resin-feeding portion 21 includes a tube 25 which is slidably mounted in a hollow guide block 26. The guide block 26 is fixed to a vertically mounted plate 27, which plate is in turn fixed to the base frame 24. A variable speed, D.C. reversing motor 28 is mounted on the guide block 26. The motor 28 is provided with a built-in speed reducing mechanism and has a pinion gear 29 provided on the end of its output shaft. The pinion gear 29 engages a gear rack 30, which is mounted on one side of the tube 25. The hollow guide block 26 has an internal channel (not shown) which slidably receives the gear rack 30 and has an opening 31 in its side to permit the pinion gear 29 to engage the rack 30.

A shelf 32 is fixed to one end of the tube 25 and the shelf 32 supports roving cakes 33. A continuous filament 34 is trained from one of the roving cakes 33 through a guide eye 35, and into a hollow tube 36. A solenoidoperated cutter 37 is mounted on the shelf 32 between the guide eye 35 and the open mouth of the hollow tube 36. The tube 36 is fixed to the tube 25 and extends through the plate 27 and the hollow guide block 26. An air line 38 leads into the tube 36 to train the filament 34 through the tube 36 by air pressure.

The splined shaft 43 (FIG. 4) has an end portion which projects outwardly from the bearing 46 and this projecting end portion is provided with a bevel gear 100 which meshes with another bevel gear 101. The bevel gear 101 is mounted for rotation on a plate 102, which is fixed to and projects outwardly from the end of the tube 25. The bevel gear 101 meshes with a bevel gear (not shown) which is associated with a drive roll 103 to rotate the roll 103 in a clockwise direction as viewed in FIG. 4. The filament 34 is fed from the end of the tube 36 and between the drive roll 103 and an idler roll 104 and into a narrow mouth portion 105 of a guide bell 106 which is fixed to the end of the plate 102.

A resin feed tube 39 is fixed to the bottom of the tube 25 and extends through the plate 27 and the hollow guide 4 block 26. A resin tank 40 is connected to the feed tube 39 by a flexible hose 41. An air pressure line 42 is connected to the top of the resin tank 40 so that the resin contained therein is fed to the resin feed tube 39 at a constant pressure.

The splined shaft 43 is axially mounted for rotation within the tube 25 by

bearings

44, 45, and '46, which are respectively provided at one end of the tube 25, at an intermediate portion of the tube 25, and at the other end of the tube 25. A length of the shaft 43 between the

bearings

44 and 45 is provided with splines 47. The gear 48 is slidably mounted on the spline 47 and is in driving relationship with the shaft 43. A longitudinal opening 49 is provided in one side of the tube 25 and the gear 48 engages a gear 50 through this opening. The gear 50 is journalled for rotation on the plate 27 and has a pair of side plates 51 which retain the gear 48 in a longitudinally fixed position relative to the gear 50 and, therefore, the plate 27. The gear 50 is driven by a ring gear 52 through an idler gear 53. The ring gear 52 is provided with a mechanical clutch 4 which alternately connects and disconnects the ring gear 52 from a main drive shaft 55 in a manner which will hereinafter become apparent.

The drive shaft 5 is journalled to the frame 24 by.

bearings 56 and is driven by a variable speed D.C. motor 57. A phenolic drive gear 5 8 is fixed to one end of the drive shaft 55 and engages a ring gear 59. The ring gear 59 is mounted at one end of a hollow centrifugal mold 60. The centrifugal mold 60 is provided with end inserts 61 and 62, which have a frustum-shaped inside surface.

The centrifugal mold 60 has annular bearing flanges 63 adjacent each end of the mold. Each bearing flange rests on a pair of phenolic bearing Wheels '64, which are mounted for rotation on the base frame 24. The top of each flange is supported by a phenolic bearing wheel 65, which is mounted in line with the vertical axis of the mold 60.

The outer surface of the mold 60 is enclosed by a hood 66. Circulating hot air is forced into the hood 66 (FIGS. 2a and 5) through an inlet opening -67 and is exhausted through an opening 68.

The chopped fiber and resin-feeding portion 23 of the machine 20 is seen most clearly in FIGS. 1b, 2b, 6 and 8. The portion 23 includes a conveyor frame '69 which is slidably mounted in a hollow guide block 70. The guide block 70 is fixed to a vertically mounted plate 71 which, in turn, is fixed to the base frame 24. A varible speed D.C. reversing motor 72 is mounted on the hollow guide block 70. The motor 72 has a built-in speed reducing mechanism and has a pinion gear 73 mounted on its output shaft. The pinion gear 73 engages a gear rack 74 which is fixed to and extends longitudinally along one side of the conveyor frame 69. The pinion gear 73 engages the gear rack 74 through an opening 75 which is provided in one side of the guide block 70.

The conveyor frame 69 comprises a pair of spaced

vertical plates

76 and 77 which are tied together by cross bars 78. A drive roll 79 is mounted for rotation at one end of the conveyor frame 69 between the

plates

76 and 77 and is driven by a motor 80. A conveyor belt 81 is wrapped around the drive roll 79 and an idler roll which is mounted for rotation at the other end of the conveyor frame 69.

The edges of the conveyor belt 81 are guided by longitudinal tracks 82 which are cut into the spaced

vertical plates

76 and 77.

A cutter 83 is mounted on the hollow guide block 70 directly over the conveyor belt 81. The cutter 83 includes a feed roll 84, an anvil roll 85, and a cutter roll 86. The feed roll 84 is driven in a counterclockwise direction, as viewed in FIG. 6, by a motor 87. A continuous fiber filament 88 is trained from roving cakes '89, through a guide eye 90, and into the bight of the feed roll 84 and the anvil roll 85. The filament 88 then passes between the anvil roll 85 and the cutter roll 86 to be chopped into relatively short fibers and dropped on the conveyor belt 81.

A resin feed tube 91 is fixed to the bottom of the plate 76 and extends longitudinally along the conveyor frame 69. A resin tank 92 is connected to the feed tube 91 by a flexible hose 93. The space in the tank above the level of the resin is maintained under pressure by an air pressure line 94 which is connected to the top of the tank 92. This insures that the resin will be fed through the tube 91 at a substantially constant pressure.

OPERATION To form a cylindrical tank sidewall having a circumferentially wound outer surface and a resin-impregnated, chopped fiber inner surface, the motor 28 is energized to drive the tube 25 into the centrifugal mold '60. The continuous filament 34 is introduced into the mouth of the tube 36 and is forced through that tube by a blast of pressurized air from the air line 38. The filament 34 is then trained between the drive roll 103 and the idler roll 1 04 and the end of the filament is fixed to one end of the mold by pressure-sensitive tape.

When the tube 25 is driven to the right hand side of the mold, as viewed in FIG. 4, a limit switch 95, which is mounted on the plate 27, is actuated by a plate 96 which is fixed to the tube 25. When the limit switch 95 is struck by the plate 96, the polarity of the motor 28 is reversed to drive the tube 25 to the left, as viewed in FIG. 4. The actuation of the switch 95 also starts the motor 57 to rotate the centrifugal mold in a counterclockwise direction (FIG. 5) and to cause the drive roll 103 and the idler roll 104 to feed the filament 34 to the inside mold surface. Actuation of the switch 95 also opens a valve (not shown) in the air pressure line 42 to force resin out of the tank 40 and through the resin feed tube 39.

The filament that is fed from the end of the tube 25 clings to the inner surface of the mold 60 by proper selection of the surface speeds of the mold 60 and the

rolls

103 and 104, and forms a predetermined pattern depending upon the operation of the reversing motor 28. For example, if a tank, having an outside diameter of inches and a circumferentially wound outer wall, is to be formed the inside diameter of the mold 60 would be 10 inches and the mold would be rotated at at least 85 rpm. to overcome the force of gravity on the filament, For a typical application, a 10-inch tank mold would be rotated at 300 rpm. and, with a 1:1 ratio between the

gears

58 and 59, the drive shaft 55 would be rotated at 300 rpm. The

gears

50, 52, 53, 48, 100, 101, and the gear (not shown) associated with the drive roll 103 would all be selected to establish a 4:1 gear ratio between the drive roll 103 and the drive shaft 55'. This 4:1 ratio permits the use of a 2 /2 inch drive roll and the insertion of the filament feeding end portion of the tube 25 into the mold 60. Although the roll 103 is driven at 1200 r.p.m., its surface speed corresponds to that of the inside surface of the centrifugal mold 60. The roll 103, however, is designed so that its diameter is slightly less than 2 /2 inches so that the surface speed of the mandrel is slightly greater than that of the roll 103. This relationship insures that a controlled loop will be formed on the inner surface of the mold 60 since, as may be seen in FIG. 5, the filament 34 will be dragged at a very slow rate in a counterclockwise direction around the inside surface of the mold.

If the pattern formed by the filament 34 on the inner surface of the mold 60 is to be a hoop or level wound pattern, i.e., a winding in which each loop is substantially contiguous to the preceding loop and is oriented at an angle of substantially ninety degrees to the longitudinal axis of the centrifugal mold 60, the speed of the motor 28 would be adjusted relative to the surface speed of the mold 60 so that the loops are substantially contiguous. The loops that are laid down on the inside surface of the mold 60 are impregnated with resin from the resin feed tube 39.

It should be appreciated that, although the gear 48 drives the spline shaft 43 while the tube 25 is being driven to the left by the gear 29, the gear 48 is held in its illustrated position by the side plates 51 on the gear 50. The operation of the gear 48-, therefore, is not dependent upon or influenced by the motion imparted to the tubes 25 by the motor 28.

The filament 34, therefore, may be laid down on the inside surface of the mold 60 in any desired pattern by changing the speed and/or the direction of operation of the motor 28.

When the filament 34 has been laid up on the inside surface of the mold 60 in the indicated manner and the tube 25 has been driven to the left, as viewed in FIG. 4, a limit switch 97, which is mounted on the hollow guide block 26, is struck by a plate 97a which is mounted near one end of the tube '25. The operation of the limit switch 97 energizes the solenoid-operated cutter 37 to sever the filament 34, stops the motor 28, and operates the mechanical clutch 54 to disengage the ring gear 52 from the drive shaft 55.

With the tube 25 in a retracted and inoperative condition, the motor 72 is energized to drive the conveyor frame 69 to the left as viewed in FIG, 6. When a limit switch 98, which is mounted on the support plate 71, is struck by a plate 99, which is mounted on the conveyor frame 69, the polarity of the motor 72 is reversed to drive the conveyor frame to the right as viewed in FIG. 6. Operation of the limit switch 98 also energizes the motor to drive the conveyor belt 81 in the direction indicated by the arrows in FIG. 6, energizes the motor 87 to operate the cutter 83, and opens a valve (not shown) in the air line 94 to force resin through the feed tube 91.

As the conveyor frame 69 traverses from left to right, as viewed in FIG. 6, the inside surface of the resin-impregnated filament 34 is coated with randomly oriented, resinimpregnated, chopped fibers. As the chopped fibers are fed from the conveyor belt 81, they are deflected downwardly by a shield which is provided at the end of the frame 69. A pressurized air line 111 is connected to the frame 69 to maintain a slight positive pressure within the belt 81 so that the chopped fibers will not foul the conveyor belt or its drive and idler rolls.

The chopped fibers and resin that are distributed on the rotating inner surface of the mold form a cylindrical and relatively thick medial portion between the end inserts 61 and 62. The centrifugal force which is imparted to the chopped fibers and resin levels the inner surface of the resin so that this surface is smooth and cylindrical and so that the ends of the relatively thick medial portion are tapered.

When the conveyor frame 69 has been retracted to one end of the mold 60, a limit switch 112, which is mounted on the hollow guide block 70, is struck by a plate 113 which is mounted on the conveyor frame 69. The actuation of the limit switch 112 deenergizes the motor 80, the motor 87, and the motor 72.

While the mold is still rotating, the temperature of the heated air within the hood 66 is raised to increase the temperature of the laid-up fiber-resin form to the setting temperature of the resin, The heated air is circulated through the hood 66 until the resin has fully set.

When the resin has fully set, the motor 57 is turned off to stop the rotation of the mold 60. The chopped fiber and resin feeding portion 23 of the machine 20 is then further retracted to permit removal of the finished molded article. To this end, longitudinal slots 114 are provided in the base frame 24 so that the vertically mounted plate 71 may be pulled away from the mold 60 when bolts 115 are loosened.

As may be seen in FIG. 9', a molded, fiber-reinforced, plastic sidewall 116 is provided with top and bottom premolded end caps 117 and 118, respectively, to form a finished tank. The top end cap 117 may be provided with a threaded access opening 119 if the finished tank is to be employed as a water softener. Each end cap is cup-shaped and includes a cylindrical wall 120 which tapers in cross section from a relatively thick bottom 121 to a relatively thin rim 122. The tapered cylindrical wall 120 of each end cap is cemented to the tapered end portions of the centrifugally molded article.

Instead of thoroughly impregnating the fibers and filaments with resin, it should be appreciated that the laid-up fibers and filaments may be partially impregnated with a thermosetting resin. In this instance, the resin acts as a binder to maintain the shape of the fiber form when the resin is cured. The binder-impregnated fiber form may be laid up in a cylindrical mold, provided with fiber end caps (or premolded end caps), and then may be thoroughly impregnated with additional resin to form a finished tank.

It is to be understood therefore that the resin impregnation step referred to in the following claims is intended to embrace both thorough and partial resin impregnation.

Many modifications and variations of the illustrated, preferred embodiment of the invention will be apparent to those skilled in the art in light of the above disclosure. Therefore, it is to be understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically shown and described herein.

What is claimed is:

1. A molding machine for making a fiber-reinforced molded plastic article comprising a molding chamber having a cylindrical inner surface comforming to the shape of the sidewall of the finished article, means for rotating said molding chamber about its longitudinal axis to establish a predetermined surface speed for the cylindrical inner surface of said molding chamber, means for feeding a continuous fiber filament into said molding chamber at a predetermined feed rate of slightly less than said surface speed of said inner surface of said molding chamber to deposit said fiber filament in a continuous strand onto said cylindrical inner surface from a point within said chamber at said filament feed rate, and means for moving said point within said molding chamber to deposit said fiber filament in a predetermined pattern on said inner surface of said molding chamber.

2. A molding machine as set forth in claim 1, including means for supplying a thermosetting resin to said molding chamber to impregnate said continuous fiber filament therewith, and means for heating said molding chamber to set said resin.

3. A molding machine as set forth in claim 1, wherein said means for feeding said continuous filament includes a feed roll having a generally cylindrical outer surface disposed within said molding chamber, and a means for rotating said feed roll at a predetermined rate so that the surface speed of said feed roll outer surface is less than the surface speed of said molding chamber inner surface.

4. A molding machine for making a fiber-reinforced molded plastic article comprising a molding chamber having a cylindrical inner surface conforming to the shape of the sidewall of the finished article, means for rotating said molding chamber about its longitudinal axis to establish a predetermined surface speed of the cylindrical inner surface of said molding chamber, means for feeding a continuous fiber filament into said molding chamber at a predetermined feed rate of slightly less than said surface speed of said inner surface of said molding chamber to deposit said fiber filament onto said cylindrical inner surface from a point within said molding chamber at said filament feed rate, means for moving said point within said molding chamber to deposit said filament in a predetermined pattern on the inner surface of said molding chamber, means for randomly distributing chopped fibers over the coiled continuous filament and the inner mold surface, means for supplying a thermosetting resin to said molding chamber to impregnate said continuous fiber filament and said chopped fibers therewith, and means for heating said molding chamber to set said resin.

5. A molding machine as set forth in claim 4 wherein said means for feeding said continuous filament includes a feed roll having a generally cylindrical outer surface disposed within said molding chamber, and a means for rotating said feed roll at a predetermined rate so that the surface speed of said feed roll outer surface is less than the surface speed of said molding chamber inner surface.

6. A molding machine as set forth in claim 4 wherein said means for moving said point orients each revolution of said continuous fiber filament at an angle of substantially degrees to said longitudinal axis of said molding chamber.

7. A molding machine as set forth in claim 4 wherein said means for distributing distributes said chopped fibers evenly over a major medial portion of said coiled continuous filament so that they have a uniformly decreasing bulk from said major medial portion to both ends of said cylindrical molding chamber to thereby taper the end portion of said cylindrical sidewall.

8. A molding machine as set forth in claim 4 wherein said means for distributing chopped fibers includes means for chopping fibers at a location outside of saidmolding chamber and means for conveying said chopped fibers from said location into said molding chamber.

References Cited UNITED STATES PATENTS 2,870,054- 1/1959 Amos et al. 18-26X 2,994,919 8/1961 Schafer et al l826 3,012,922 12/1961 Wiltshire l826X 3,052,927 9/1962 Hoppe et al. l826 3,112,530 12/1963 Boggs et al. l826 3,206,821 9/1965 Keyser et a1 2530CX 3,133,563 5/1964 Smith 141-12 3,150,219 9/1964 Schmidt 264258 FOREIGN PATENTS 1,329,371 4/1963 France.

I. SPENCER OVERHOLSER, Primary Examiner US. Cl. X.R.

UNITED STATES PATENT OFFIICE CERTIFICATE OF CORRECTION Dat Januarv 19 1921 Patent No. 3,555,614

InventorCs) ARTHUR J. WILTSHIRE It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

change change change change change change change "suit able" to suitably--.

Signed and sealed this 7th day of September 1971.

Column 1, line Column 2, line and line

Column 3, line Column 4, line line line

(SEAL) Attest:

EDWARD M.F'LETCHER, JR.

Attesting Officer ROBERT GOTTSCHALK Acting Commissioner of Paten