MXPA98010297A - Method for distributing resin reinforcement fibers - Google Patents

Abstract

A method for distributing reinforcing fibers to manufacture for a mine preform includes winding a continuous length of a reinforcing fiber (16) in coils (28) about a shape (52) having a longitudinal axis, moving the horns axially with with respect to the shape for coupling a cutter (60), cutting the coils to form discrete length reinforcing fibers (64), applying a resin material to the discrete fibers, and distributing the discrete length reinforcing fibers (

Description

METHOD FOR DISTRIBUTING RESINATED REINFORCEMENT FIBERS TECHNICAL FIELD This invention pertains to distribution reinforcing fibers, particularly in the manufacture of a preform suitable for reinforcing molded articles, such as structural compositions. More particularly, the invention pertains to the reception of a continuous length of a reinforcing fiber, cutting the reinforcement fiber into discrete lengths, and distributing the discrete lengths over a collection surface.

BACKGROUND Structural compositions and other molded reinforcement articles are commonly manufactured by resin transfer molding and structural resin injection molding. These molding processes have become more efficient by preforming the reinforcing fibers in a reinforcing layer or plate, which approximates shape and size to the molded article, before inserting the reinforcements into the mold. To be acceptable for production at an industrial level, a rapid preforming procedure is required. In the manufacture of preforms, a common practice is to provide a continuous length of strand or reinforcing fiber to a chopper, which cuts the continuous fiber into many fibers of discrete length, and deposits the fibers of discrete length on a collection surface. This process can be used to make preforms in an automated way by mounting the stiffener distributor to move on the picking surface, and scheduling the movement of the stiffener to apply the stiffener fibers in a predetermined, desired pattern. The reinforcement distributor can be robotized or automated, and such reinforcement fiber distributors are known in the art for uses such as the manufacture of preforms for long structural parts, such as in the automotive industry, for example. Typically, the preforms are sprinkled with a powdered binder, and placed in a mold. The heat and pressure of the mold harden the binder, producing a preform of reinforcing fibers, which can be stored and transported to the final molding customer, who applies resin to the preform and shapes the resin preform to produce a reinforced product. , typically using a resin injection process. The process for cutting continuous reinforcing fibers into discrete lengths of reinforcing fibers is useful in the manufacture of sheets as well as in the manufacture of preforms. The distributors of reinforcement fibers for film manufacture can also be adapted to be mobile and programmable. When the technical requirements for reinforcement products increase, new methods for distributing and formulating reinforcing fibers are required, one requirement is that reinforcing fibers be produced at faster speeds than previously used. The pre-fabrication technology must allow a flexible and programmable fiber reinforcing distributor to meet the requirements for highly sophisticated fiber patterns and orientations. and specific orientations of the reinforcing fibers to improve the strength of the molded product precisely in the weakest or most stressed place of the product to be molded.Through this new sophistication, there is often a requirement that the fibers fall on a collection surface in a po co separate, parallel. Efforts to produce closely spaced, generally parallel fibers have not been successful, especially at the high speeds required for commercially successful operations. When the typical strand chopper nozzles are operated at a faster speed, the resulting discrete stiffening fibers can not fall successfully in parallel, in a little separated orientation.

The fibers are directed towards the collection surface in a direction generally perpendicular to the surface This method does not tend to leave the fibers generally parallel and spaced apart, and the nozzle distribution devices use air flows to guide the reinforcing fiber in coupling with the chopper blade, and to distribute the fiber. It is clear that improvements in the cutting of continuous reinforcing fibers in discrete lengths and the distribution of them in a little separated arrangement, generally parallel, would be desirable, and thus introduce turbulence into the preform harvesting surface. .

DESCRIPTION OF THE INVENTION A method and apparatus for distributing reinforcing fibers has now been developed, which overcomes the disadvantages of the methods developed above. The method of the invention winds the continuous reinforcing fiber • around a shape, such as a cylinder or a pair of rods, to form rings or coils. The coils are then slid or moved axially in the manner in which the coils are coupled to a cutter. The coils are cut into fibers in discrete length and are then distributed in a generally parallel arrangement, little separated. The method of the invention allows the feed rate of the continuous fiber to be increased, still releasing the discrete reinforcing fibers in an orientation generally parallel to the picking surface. According to this invention, there is provided a method for distributing reinforcing fibers, comprising winding a continuous length of a reinforcing fiber in coils about a shape having a longitudinal axis, moving the coils axially with respect to the form for coupling a cutter, cut the coils to form discrete length reinforcing fibers, and distribute the discrete length reinforcing fibers. In general, the discrete length reinforcing fibers are distributed in an axial direction with respect to the shape, although they could be distributed in another direction by means of an air jet or deflector if desired. The method of the invention allows the discrete length reinforcing fibers to be distributed relatively parallel to each other. If the collection surface is generally horizontal, the discrete length reinforcement fibers can be distributed generally parallel to the collection surface. In a specific embodiment, the discrete length reinforcing fibers are oriented generally perpendicular to the axis of the shape when they are distributed. In a specific embodiment of the invention, the "shape around which the continuous reinforcing fiber is wound to form the coils comprises two or more rods, the shape can also be a cylinder around which the continuous reinforcing fiber is wound on. In another embodiment, the shape is a cone member around which the continuous reinforcement fiber is wound onto coils In yet another embodiment of the invention, the cutter is a knife blade The cutter can be adapted to cut each coil once, to form a single discrete length reinforcement of each ring, or two or more cutters can be used to make two or more discrete length reinforcements of each ring.A guide can be used to direct discrete length reinforcements so that are distributed generally parallel to each other In a preferred embodiment of the invention, the movement of the coils axially with respect to the shape for coupling the co It is achieved by coupling the coils with a helical surface, which can be a nail or more coil springs that rotate in relation to the coils. In yet another embodiment of the invention, the fibers of discrete length are resinized before being distributed.

According to this invention, there is also provided an apparatus for distributing reinforcing fibers, which comprises a shape having a longitudinal axis, an "embobinator for winding a continuous length of a reinforcement fiber in coils around the shape, a cutter for cutting the coils to form discrete length reinforcing fibers, a coil motor for moving the coils axially with respect to the shape for coupling the cutter and distributing the discrete length reinforcing fibers.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic perspective view illustrating a reinforcing distributor depositing discrete reinforcing fibers on a preformed molding surface. Figure 2 is a cross-sectional, schematic, elevation view of the reinforcement distributor for distributing reinforcing fibers according to the invention, with the coil spring removed for clarity. Figure 3 is a cross-sectional, schematic, elevation view of a portion of the stiffening distributor of Figure 2, showing the coil spring. Figure 4 is a cross-sectional plan view, taken along line 4-4 of Figure 3.

Figure 5 is a cross-sectional elevation view taken along line 5-5 of Figure 4. Figure 6 is a cross-sectional, "schematic, elevation view of an alternative apparatus for Figure 7 is a cross-sectional, schematic, elevational view of another apparatus for carrying out the invention, Figure 8 is a schematic, partially cut-away, plan view of a Apparatus for applying resin to discrete fibers according to the method of the invention Figure 9 is a cross-sectional elevation view of the apparatus of Figure 8 taken along line 9-9. is a cross-sectional view of the exploded view, in elevation of the apparatus of Figure 9, taken along line 10-10.

BEST MODE FOR CARRYING OUT THE INVENTION As shown in Figure 1, a robotic reinforcement distributor 10 is positioned to deposit discrete reinforcing fibers 12 on a collection surface, such as the molding surface of the preform 14. Typically The molding surface of the preform is a mesh. The reinforcement distributor does not need to be robotized or automated, and could still be stationary with the picking surface being mobile. A vacuum source is usually placed under the mesh to facilitate the manufacturing process of the preform. The continuous reinforcing fiber 16, distributed from a source not shown, is transported to the fiber distributor where the continuous reinforcing fiber is cut or cut to ... produce the discrete length reinforcing fibers. The continuous reinforcing fiber may be of any suitable material for reinforcement purposes. A preferred material is Type 30® glass fibers, available from O ens-Corning Fiberglas Corporation, Toledo, Ohio, although other mineral fibers and organic fibers, such as polyester, Kevlar® and carbon fibers, can be used with the invention. It should be understood that the continuous fiber may be a single filament (monofilament) or a strand comprised of numerous filaments. As shown in Figure 2, the continuous reinforcing fiber is fed to the distributor by means of feed wheels 20 and, which also act to reduce the tendency of the fiber to be twisted to migrate upwards to the source of continuous reinforcement. The continuous fiber is then fed along the outer surface of a rotating member, such as the rotor 22. The rotor can be mounted to rotate by any suitable means, such as by the motor 24. On each downstream of the rotor is find a shape around which the continuous reinforcement bra is wound by the rotating action of the rotor. The shape can be in any suitable way to receive the turns of the continuous reinforcing fiber. In the embodiment shown in Figure 2, the shape comprises a pair of rods 26 around which the continuous reinforcing fiber is wound into a series of generally parallel rings or beams 28. The shape (or rods 26), is not shows moving, but has a longitudinal axis 30, which can also be collinear with the axis of revolution of the rotor. It must be understood that in an alternative design the form (ie, on the rods) could be rotated, and the rotor could be stationary. In this arrangement the same result could be provided by winding the continuous reinforcing fiber in coils around the shape. Also, both the shape and the rotor could be mounted to rotate, and could be rotated at different speeds to allow the continuous fiber to be wound around the shape to create the coils. Once the coils are placed around the shape, the coils move downstream, axially of the shape (to the left in Figure 2). Any means for moving the coils axially with respect to the shape can be used. As shown in Figure 3, the coils can be moved downstream by the action of a helical surface, such as a coil spring 32. For illustration purposes the coil spring is not shown in Figure 2. The coil spring is mounted to rotate it by any suitable means, such as a thimble 34. The rotation of the coil spring causes the spring surface to engage the coils of the continuous fiber and push the coils axially with respect to the shape. Other means for moving the coils axially with respect to the shape is a vibrational system which vibrates the rods and uses gravity to make the coils move downward. When the coils move axially with respect to the shape, they are coupled by a cutter, which makes one or more cuts in each ring or coil 28. The cutter can be of any type capable of separating the continuous reinforcing fiber in discrete lengths fiber 12. Examples of cutters include heating devices and lasers. As shown in Figures 3-5, the cutter can be a blade mounted on the shape itself, such as the blades 36 mounted on each of the rods 26. Placed adjacent to the blades, there are cot or cots rollers 38. , which act to • Sharply press the continuous reinforcing fiber, on the blade, to ensure cutting rather than simply pulling the fiber through the blade. The cots used with the cutters are well known, and can also be of any suitable material. If desired, the cots can be mounted to rotate. As shown in Figure 5, after the coils 28 are cut by the blade, they move downward as discrete lengths of fibers 12. To ensure that the discrete lengths of fibers remain in a generally parallel, closely spaced form on the molding surface of the preform, a guide can be used, such as the plates 40. The plates help to align the fibers of discrete length, and ensure that they are distributed in a controlled, uniform manner. Discrete lengths are distributed in an axial direction with respect to the rods, although deflectors or air jets could be used to distribute fibers of discrete length in other directions Since the fibers of discrete length are formed by cutting the coils, they are oriented generally perpendicular to the axis of the shape when they are distributed, and are generally parallel to the molding surface of the preform 14. Even that the shape around which the continuous reinforcing fiber 16 is rolled, is shown in Figures 2-5 as a pair of rods 26, the shape can be of other configurations. For example, the shape can be of three generally parallel rods. The shape could be a cylinder. The shape could also be a conical member, as "shown in Figure 6. The tapered member 42 is mounted to rotate, by means not shown, placed downstream of the rotor 22. The rotor rotates to distribute the continuous reinforcing fiber 16 in the coils 28 wound around the conical member. The coils are coupled or driven by any suitable means, such as a conveyor or belt 44 and pulled or moved axially with respect to the shape, i.e., the conical member. Positioned opposite the band, is a cutter, which may be in the form of a cutter wheel 46 and a cot 48 wheel. When the bobbins are pulled axially with respect to the conical member by the band (to the left, as shown) in Figure 6), the coils will be cut to form the fibers of discrete length 12. The method for distributing fibers of discrete length using two blades, as shown in Figures 2-5, results in two discrete fibers for each of coils 28. Using only one blade, as shown in Figure 6, results in only one discrete fiber per coil. In such a case, it may be advantageous for the apparatus handling the fiber, modified guide plates to be adapted, not shown, to open up the fibers of discrete length after cutting them, and to align them in a generally parallel orientation. As shown in Figure 7, the shape around which the continuous reinforcing fiber 16 is to be wound can be a pair of rotating helical screws 50. The coils 28 are wound around the helical screws by the rotor 22. The rotational action of the helical screws forces the coils to move axially with respect to the shape, i.e., the helical screws, and to engage with the blade 36. Although two blades are shown in Figure 7, a blade could be used. The blades cut the coils into discrete lengths of fiber, which are distributed in an axial direction with respect to the shape (helical screws). As shown in Figures 8, 9 and 10, the discrete length reinforcing fibers can be resinated before being distributed. The continuous reinforcing fiber 16 is fed to the distributor, and then fed along the outer surface of the rotating rotor 22. The continuous fiber is wound on the coils 28 around the shape 52, which can be in any suitable way to receive the winding of the fiber of the continuous reinforcing fiber. The shape has a longitudinal axis 30, which can also be collinear with the axis of revolution of the rotor. Once the coils are placed around the shape, the coils are moved downstream, axially of the shape (to the right in Figures 8 and 9). The coils are moved downstream by the action of upper and lower conveyor belts 54 and 55, respectively, which are located on both sides of the wedge-shaped melting plate 58, as shown more clearly in the Figure 9. The upper conveyor 54 does not extend across the full width of the shape 52, and is positioned between two knife blades in the form of blade wheels 60 (only one of which is shown in Figure 8). The knife wheels push the coils 28 against the cot rolls 62 to cut the coils into discrete length reinforcing fibers 64. Those discrete fibers are moved in the downstream direction as two discrete fiber flows by the action of the upper conveyor belts and lower 54 and 55, which keep the discrete fibers in contact with the upper and lower surfaces 56 and 57, respectively, of the wedge-shaped fusion plate 58. The two discrete fiber flows 64 melt at the current end below the melting plate to form a "combined flow" of discrete fibers that move axially with respect to the shape, and are generally oriented perpendicularly to the axis of the shape.

At the downstream end of the fusion plate 58 is a resin plate 66 having a resin surface 68. The discrete fibers are moved along the resin surface by the action of two relatively wide outer bands 70 and 72, and a narrow inner band 74. The discrete fibers could also be moved by any other suitable means, such as a wheel or plurality of wheels, not shown. When the fibers move along the resin surface, they are oriented generally perpendicular to the axial direction 30. The initial edge of the inner band 74 lies downstream from the leading edges of the two outer bands to avoid interference with the upper conveyor belt 54. When the three bands 70, 72 and 74 move the discrete fibers along the resin surface 68, resin is applied to the fibers by injecting the resin through a slot 76 in the resin plate 66 for create resin fibers 78. The preferred resin is a liquid, although resin may also be applied in powder form. The resin is supplied to the slot 76 by means of a resin conduit 80 from a source, not shown. Although a groove is shown, the resin can be injected through any suitable opening in the resin surface. As can be seen in Figure 10, the slot has a length considerably smaller than the length of the discrete fibers 64. The liquid resin is initially applied to the discrete fibers in the central portion 82 of each fiber, and flows or diffuses towards the end portions 84 of the fibers when the fibers are moved downstream along the resin surface. By applying the resin under pressure in the central portion and causing the resin to flow, the air surrounding the fibers can be removed, thus ensuring that all the fibers are coated with the resin and that there are no air pockets. The resin injected into the discrete fibers can be a thermosetting resin, such as a polyester, epoxy, phenolic or polyurethane resin. The resin can also be a thermoplastic resin such as Nyrim® resin or others. The discrete fibers can be glass fibers having a weight in the range of about 300 to about 4800 g / km, and a diameter in the range of about 8 to about 30 microns. For a wick of 2400 g / km and a diameter of 17 microns, the yield could range from about 0.1 to about 5 kg of -glass fibers per minute, with a total yield (resin and glass) within the range of about 0. -? up to approximately 15 kg per minute. It will be apparent from the foregoing that various modifications to this invention can be made. It is considered, however, that such are within the scope of the invention.

INDUSTRIAL APPLICABILITY The invention can be useful for manufacturing preforms, preimpregnated products and SMC, suitable for molding processes and for manufacturing reinforced sheets.

Claims (20)

1. REIVIIfDICATIONS R 1. A method for distributing reinforcing fibers, characterized in that it comprises winding a continuous length of a reinforcing fiber in coils about a shape having a longitudinal axis, which moves the coils in an a direction with respect to the form for coupling a cutter, cut the coils to form discrete length reinforcing fibers, apply a resinous material to the discrete fibers, and distribute the discrete resin fibers.
2. 2. The method according to claim 1, characterized in that the resin is a liquid resin.
3. The method according to claim 1, characterized in that it includes moving the discrete fibers along a resin surface, and applying the resin to the discrete fibers by introducing the resin through an opening in the resin surface.
4. 4. The method according to claim 3, characterized in that the opening is a slot through which the resin is introduced.
5. The method according to claim 4, characterized in that the slot has a length which is smaller. that the length of the discrete fibers, and in which the resin diffuses from a central portion of the discrete fibers towards the end portions of the discrete fibers when the discrete fibers move along the resin surface.
6. 6. The method according to claim 3, carapterized because it includes moving the discrete fibers along the resin surface with a conveyor.
7. 7. The method according to claim 1, characterized in that the step of moving the discrete fibers moves them in an a direction with respect to the shape.
8. 8. The method of compliance with the claim 7, characterized in that the discrete fibers are oriented generally perpendicular to the a direction during the step of moving the discrete fibers along the resin surface.
9. A method for distributing reinforcing fibers, characterized in that it comprises winding a continuous length of a reinforcing fiber in coils about a shape having a longitudinal axis, moving the coils in an a direction with respect to the shape for coupling a cutter , cutting the coils to form discrete length reinforcing fibers, moving the discrete fibers along a resin surface, applying a liquid resin to the discrete fibers by introducing the resin through an opening in the resin surface, and distribute discrete resin fibers.
10. 10. The method in accordance with the claim 9, characterized in that the opening is a slot through which the resin is introduced, and the slot has a length that is less than the length of the discrete fibers, and in which the resin is defined from a central portion of the discrete fibers towards the end portions of the discrete fibers when the discrete fibers move along the resin surface.
11. The method according to claim 9, characterized in that it includes moving the discrete fibers along the resin surface with a conveyor.
12. 12. The method in accordance with the claim 10, characterized in that the step of moving the discrete fibers moves them in an a direction with respect to the shape.
13. 13. The method according to the claim 11, characterized in that the discrete fibers are oriented generally perpendicular to the a direction during the step of moving the discrete fibers along the resin surface.
14. The method according to claim 13, characterized in that the cutter is a knife blade, and in which the cutter cuts each reel into at least two discrete fibers.
15. 15. A method for distributing reinforcing fibers * characterized in that it comprises winding a continuous length of a reinforcement fiber in coils around a "having a longitudinal axis, moving the coils in an axial direction with respect to the shape for coupling a cutter, cutting each of the coils to form two flows of discrete fiber reinforcing fibers, moving the discrete fiber flux in the axial direction and in contact with the upper and lower surface of a wedge-shaped plate, melting two discrete fiber flows to form a combined flow of discrete fibers, applying a resinous material to the combined flow of discrete fibers, and distributing the fibers Discrete resins
16. 16. The method according to claim 15, characterized in that the movement of the discrete fiber flow along the upper wedge surface is achieved by means of a conveyor, and the flow movement of discrete fibers at the length of the lower wedge surface is achieved by means of a conveyor
17. 17. The method according to the claim 15, characterized in that it includes moving the combined flow of discrete fibers along a resin surface, and applying the resin to the discrete fibers by introducing the resin through a groove in the resin surface.
18. 18. The method in accordance with the claim 17, characterized in that the slot has a length which is smaller than the length of the discrete fibers, and in the "which resin diffuses from a central portion of the discrete fibers towards the end portions of discrete fibers when the discrete fibers move along the resin surface."
19. 19. The method according to claim 1. 18, characterized in that the movement of the flow of discrete fibers along the upper wedge surface is achieved by means of a conveyor, and the movement of the discrete fiber flow along the lower wedge surface is achieved by means of of a conveyor. The method according to claim 19, characterized in that the discrete fibers in the combined flow are oriented generally perpendicular to the axial direction during the step of moving the combined flow, and in which the combined flow of discrete fibers is moves in an axial direction with respect to the shape during the step of moving the combined flow.