FR2847564A1 - Procedure and machine for making cylindrical composition components uses centrifuging in high-speed cylindrical mandrel fed with resin and reinforcing filaments - Google Patents

Abstract

The procedure consists of feeding a resin into a cylindrical mandrel (1) rotating at high speed and, after the first layer of resin has spread over the inner surface of the mandrel, feeding in successive layers of reinforcing filaments and resin until a required thickness is achieved. Polymerisation is then carried out at a slower speed with optional application of heat. The mandrel is rotated by external rollers and is fed with resin and reinforcing filaments through a rotating hollow shaft (2) mounted on a mobile arrangement that allows it to move to and fro inside the mandrel. The shaft is also fitted with a magazine for storing a number of reels of reinforcing filaments, guided by rollers, air jets and curved tubes with anti-adhesive coatings and ceramic eyelets. The resin and a feed pump for it are held separately from the hollow shaft, and the machine is mounted on a heavy frame with balancing weights.

Description

Machine for manufacturing composite cylindrical parts by

  centrifugation and by winding a continuous layer of reinforcing threads.

Technical area

  The present invention relates to an improvement made to machines for manufacturing cylindrical composite parts using the principle of centrifugation. This improvement consists in allowing the deposition of a continuous ply 10 of reinforcing threads inside a rotating tube which will be called in the following document the mandrel. This reinforcement removal principle is characteristic of the "filamentary" winding, but this is carried out on the external surface of the mandrel. The principle of the present invention is therefore to produce this winding of continuous reinforcing wires inside a rotating mandrel.

  The idea is therefore to combine the principles of the centrifugation and filament winding processes in order to combine the advantages. These advantages being mainly for centrifugation: Very smooth internal and external surface conditions; * Perfect degassing (or "bubbling") of the stratification improving the adhesion of the reinforcements to the matrix and therefore the mechanical performance of the material; 25. The reinforcing materials being generally denser than the resin, a distribution of the materials going in the direction of better sealing against fluids, the concentration of resin being higher on the internal face of the tube; * A homogeneous tension over the entire length of the reinforcing threads allowing good handling of stresses; * Easy release because the removal due to polymerization (about 1 to 2% for a polyester resin) is done in the right direction; ò The possibility of easily closing the mandrel at the ends in order to isolate the external environment from solvent emissions such as styrene and to deal more easily with this type of rejection;

  * The possibility of making a sandwich structure.

  for the "filamentary" winding Due to the continuity of the reinforcing wires, obtaining optimal mechanical performance. Previous techniques In order to manufacture composite composite revolution parts, it is therefore generally used

  two industrial processes which are: centrifugation and filament winding.

  For centrifugation, the principle can be as follows: After having deposited a reinforcement inside the tube in the form of a fabric of reinforcements with oriented fibers called "rowing"; the mandrel is put into rapid rotation, then the resin is introduced gradually using a spreading device. Finally the mandrel is rotated very quickly to ensure compaction, impregnation of the resin and degassing. The polymerization takes place at a lower speed of rotation. This can be accelerated by heating the mold or by blowing hot air. The operation

  can be repeated several times in order to have several layers or to create a sandwich structure.

  This process can be simplified by the simultaneous deposit of fibers

cut reinforcement and resin.

  Manufacturing example: Petroleum tank incorporating a gravelly core Example of required rotation speed: diameter 200 by 1500 and thickness of 4 mm

  * Resin introduction: 500 rpm.

  * Impregnation: 3 mm at 1700 rpm.

  For the filament winding the principle can be as follows: A mandrel constituting the mold on which the part is formed is rotated on a gantry of manufacture called tacker. This speed of rotation allows a winding speed of a layer of reinforcing threads of the order of one meter per second. The ply of threads is wound in several layers on the mandrel and is distributed using a feed cart. This carriage ensures the supply of the wires from the reels of the reels, the constitution of the sheet, the tension, its impregnation with resin and finally its removal.

  along the mandrel. This carriage works like that of a metallurgical lathe in several passes and with an advance which is a function of the width of the sheet. After polymerization, the mandrel must be able to retract in order to release the part.

  Different refinements of this principle exist which allow helical windings or windings on parts with complex surfaces such as rocket tanks or helicopter blades.

  This principle allows the production of very large parts. Above all, it allows

  achieve very high mechanical characteristics.

  The reinforcing threads used must be untwisted and are commonly called "roving", their title (mass in g per km) and of the order of

2200 tex.

  Disclosure of the invention The principle of the invention consists in combining the principles of the two aforementioned methods by creating a device for feeding wires and resins capable of: * storing the reinforcement coils, * constituting a sheet or an assembly wires and bring them into a centrifuge machine; * guide and deposit the wires on the internal surface of the mandrel by winding,

  * bring the resin on demand.

  For this, the wire and resin supply device which will be called in the following document "rotary feeder", must be able to operate in the rotating reference frame of the rotating mandrel. This device must rotate at a speed close to the mandrel. This speed offset corresponds in this frame of reference rotating to the speed used to wind a sheet of reinforcing threads during a filament winding process. This speed shift between two rotating machines can be easily achieved electronically by servo-control by frequency variation of the

  power supplies for drive motors.

  The manufacturing of a simple part is then carried out as follows: 1. The mandrel is rotated; 2. A first layer of resin is spread by the rotary feeder itself in rotation at a given speed delta relative to the speed of rotation of the mandrel. This delta corresponds to the winding speed of the ply of reinforcing threads inside the mandrel; 3. Then the wires are brought and deposited in a successive layer on the internal surface of the mandrel as well as a regulated supply of resin; 4. When the desired thickness of laminate is reached, the rotary feeder is disengaged from the tube; 5. The mandrel is set in rapid rotation for compaction, resin impregnation and degassing; 6. The polymerization is carried out in slower rotation possibly assisted

by heating.

  The main advantages of this innovation are: * A possible closure of the ends during the deposition of resin making it possible to reduce the styrene emissions (heating and possible gas evacuation device in the axis)

  The centrifugation and densities of the materials used giving a higher resin concentration inside the tube than at the periphery and therefore better sealing.

  Significant degassing and compaction giving good mechanical characteristics; U A perfectly homogeneous tension of the threads over their entire length; * The possibility of adding a core (sandwich structure) with a filamentary deposit;

  * The possibility of adding cores in the mandrel in order to make reservations, by adjusting the balancing of the rotating assemblies.

Brief description of the drawings

  The invention and the advantages which emerge therefrom will be better understood thanks to the embodiment which is given by way of indication but not limitation, and which is illustrated by the appended diagrams in which FIG. 1 is an overview of an installation for making a filament winding inside a mandrel of a centrifuge machine;

  Figure 2 is a detail view of the rotary feeder for bringing the resin and the son on the inner face of the rotating mandrel of a centrifuge machine.

Way of realizing the invention

  Referring to the appended figures, the device according to the invention is intended to wind a sheet of reinforcing threads inside the mandrel of a centrifuge machine.

  In general, it emerges from Figure 1, such a production line therefore essentially consists of a centrifugation machine, designated by the general reference (1) for forming the cylindrical part. This machine consists mainly of a mandrel rotated on rollers and the rotary feeder, designated by the general reference (2) allowing

  to bring the resin and the reinforcing wires and to wind them on the internal surface of the mandrel.

  The rotary feed device shown in detail in Figure 2 consists mainly of a hollow shaft mounted on a movable assembly (4) allowing the carriage movements inside the mandrel (5), This hollow shaft is equipped with 'A barrel (6) for storing a number of coils (7) of reinforcing threads (in Figure 2 eight coils are shown). One can envisage several barrels (6) in series on the same hollow shaft (3) in order to increase the

  number of wires deposited and thus reduce winding times.

  The spool of threads (7) being installed, each thread is pulled from inside the spool and guided by a set of servo-driven thread guide rollers (8) whose roles are: - to press the thread; - to regulate the tension of the thread - to be a motor during the phase of placing the thread through the hollow shaft (3) this before the start of manufacturing operations. An air jet guidance system (9) for bringing the wire to the final guidance (12) on the mandrel (5). This system is realized by a bent tube with a non-stick coating type Teflon at the point where there is

  a change of direction (11). In another embodiment, a return system to 90 by roller (not shown) can be used.

  - To cut the wire by blocking the rollers when the quantity of reinforcements is reached, just before the high speed centrifugation phase;

  - To control by a servo the quantity of wound wire &.

  Each wire is thus guided to the deposit area (12) on the mandrel. The guide arm (13) bringing the wire to the deposit area (12) may consist of a tube with an end (12) of a ceramic eyelet. Each tube can be removable and replaced by another shorter or longer depending on the diameter of the mandrel (5). There are of course as many tubes as there are wires distributed at the end around the circumference of the hollow shaft (3). The wire emerging from the ceramic eyelet (12) is pressed onto the inner surface of the mandrel by centrifugal force. The air jet (9) is only used during the start phase to position the wire by making it pass through the hollow shaft (3) and the guide arm (13).

  The resin is stored outside the rotary feeder as well as the feed pump which is also external. A hose fitted with a rotary connector is connected at the end of the hollow shaft (3) to the transport tube (14> which supplies the resin spray head (15).

  The assembly is supported by a heavy and reinforced frame (16). Dynamic balancing of the barrel (6) is carried out by means of jacks displacing weights, these being controlled by so-called intelligent bearings provided with stress sensors.

  The stroke of the feed assembly corresponds to the length of the workpiece (L)

Claims (8)

1 Method of manufacturing a cylindrical composite part by   centrifugation of the type to rotate a mandrel at high speed, to bring a resin inside said mandrel, then to carry out the shaping and the compacting and degassing of the resin, then to ensure a polymerization at rotational speed weaker, characterized in that it further consists, after a first layer of resin has been spread, of bringing resin in a controlled manner and of the reinforcing threads and of depositing them in successive layers on the internal surface of the mandrel already coated with resin by a rotary distribution at a speed close to that of the mandrel with a corresponding speed shift in this reference frame rotating at the speed used to wind the ply of wire and an advance of the supply means by a movement of turning, means disengaging when the desired thickness of laminate is reached.   2 Device for implementing the method according to claim 1 characterized in that it consists of a centrifuge machine (1) for forming the cylindrical part, mainly consisting of a mandrel rotated on rollers and rotary supply device 20 formed by a hollow shaft (2) making it possible to bring the resin and the reinforcing wires and to wind them on the internal surface of the mandrel, the said hollow shaft being mounted on a movable assembly ( 4> allowing carriage movements inside the mandrel (5), the said hollow shaft being equipped with at least one barrel (6) making it possible to store a number of coils (7> of reinforcement wires.   3 Device according to claim 2 characterized in that each wire is drawn from the inside of the corresponding coil. and guided by a set of thread guide rollers (8) allowing the wire to be pressed, the thread tension to be regulated, the motor to be driven during the placement phase of the   wire through the hollow shaft (3) this before the start of manufacturing operations.   4 Device according to claims 2 and 3 characterized in that it further comprises an air jet guide system (9) for bringing the wire to a final guide (12) on the mandrel (5) .     Device according to claims 2, 3 and 4 characterized in that the guide system further comprises, for each guided wire, a bent tube with a non-stick coating of the "TEFLON" type at the point where there is a change of direction (11 ).   60 Device according to claims 2, 3 and 4 characterized in that the guide system   further includes a system for returning to 900 per roller.   Device according to claim 5 or 6 characterized in that each tube comprises at the end a ceramic eyelet (12)   Device according to claim 5 or 6 and 7 characterized in that each tube is removable so that it can be replaced by another longer or shorter depending on the diameter of the mandrel (5).   90 Device according to any one of claims 2 to 8 characterized in that it comprises several barrels (6) in series on the same hollow shaft (3) in order to increase the number of wires deposited and thus reduce the time of winding with as many tubes as there are distributed wires.   Device according to any one of Claims 2 to 9, characterized in that the resin 10 is stored outside the rotary supply device (3) as well as the feed pump for the said resin which is also external and in that a hose fitted with a rotary connector is connected at the end of the hollow shaft (3) to a transport tube (14) which supplies a resin spray head (15).   110 Device according to any one of claims 2 to 10 characterized in that the assembly is supported by a heavy frame and in that a dynamic balancing of the barrel (6) is carried out by means of jacks displacing weights, these ci being slaved to so-called intelligent bearings provided with stress sensors.   12 Device according to one of claims 2 to 11 characterized in that the mandrel (1) and the hollow shaft (3) are driven by separate motors whose speed shifting is achieved electronically by a servo control by variation of frequency of said drive motors.