Method and apparatus for production of carbon fiber components

Abstract

A method of manufacture of a carbon fiber article comprises providing a preform mold having a region that is shaped to compliment a shape of a preform part that is to be produced the surface being provided with at least one bore or groove that is connected to at least one conduit that passes through the mold to a manifold, laying a sheet of release material onto the surface covering at least some of the plurality of holes, applying reduced pressure to the manifold to cause the sheet to be sucked down onto the mold surface, laying carbon fiber material into the mold on top of the sheet of release material, applying an increase pressure to the manifold to push the preform free from the mold surface, and removing the preform from the mold.

Claims

1. A method of manufacture of a carbon fiber article comprising: (a) providing a preform mold having a region that is shaped to compliment a shape of a preform part that is to be produced, wherein the surface of the mold includes at least one bore or groove that is connected to at least one conduit that passes through the mold to a manifold, (b) laying a sheet of release material onto the surface covering the at least one bore or groove, (c) applying reduced pressure to the at least one bore or groove by way of the manifold to cause the sheet to be sucked down onto the mold surface, (d) laying carbon fiber material into the mold on top of the sheet of release material, (e) applying an increase pressure to the at least one bore or groove by way of the manifold to push the preform free from the mold surface, (f) removing the preform from the mold, and (g) feeding a chilled liquid into the mold through the manifold to the at least one conduit to cool the mold.

2. The method according to claim 1 wherein the step (g) of feeding the chilled liquid into the mold is carried out prior to the step (e) of applying the increased pressure.

3. The method according to claim 1 wherein the step (e) of applying the increased pressure is carried out by pumping a fluid under pressure into the mold through the manifold.

4. The method according to claim 1 further including the additional step, after the preform has been laid up, of chilling the mold to a temperature and for a sufficient length of time for the preform material to at least partially freeze.

5. The method according to claim 1 further including the step of, after the preform has been chilled and released, moving the preform into a mold where it is cured under either heat or pressure or both to form the finished molded part.

6. The method according to claim 1 wherein the step of removing the preform out of the mold is carried out by a robot.

7. The method according to claim 1 wherein at least one, or all of the steps are performed in a temperature controlled environment in which the temperature is below 5 degrees C.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a perspective view from above and to one side of a mold for use in a method of making a carbon fiber part according to a first embodiment of the invention;

(2) FIG. 2 shows the part in perspective view from below and to one side;

(3) FIG. 3 shows the mold in cross section with some of the internal conduits visible,

(4) FIG. 4 is a view of the mold in cross section with the internal conduits omitted for clarity in a position prior to use;

(5) FIG. 5 shows a first step in a process of making a carbon fiber article using the mold;

(6) FIG. 6 shows a second step in a process of making a carbon fiber article using the mold;

(7) FIG. 7 shows a third step in a process of making a carbon fiber article using the mold;

(8) FIG. 8 shows a fourth step in a process of making a carbon fiber article using the mold; and

(9) FIG. 9 shows a final step in a process of making a carbon fiber article using the mold; and

(10) FIG. 10 shows the mold connected to other apparatus when in use.

DETAILED DESCRIPTION

(11) FIGS. 1 to 3 and FIG. 10 show, in a position prior to use, an apparatus 1 of the present invention for use in making carbon fiber composite components. The apparatus 1 comprises a mold part 2 which takes the form of a shaped block of solid material. In this example the block is a metal alloy. The upper surface of the block has a cutout formed into it which is an exact negative copy of a surface of a part to be molded. The recess therefore has the shape that would result if the part was pushed down into the surface and left an imprint. The rear 4 (underside) of the mold is cut away in this example to reduce the weight and amount of material used, and reduce the thermal mass of the block, although this is not essential to the function of the mold. This can be seen in FIG. 2.

(12) Formed into the block are multiple conduits 5, each a few mm in diameter, that extend from a manifold 6 in one side face of the block to end at respective openings 7 in the surface of the mold. These openings, each a small circular hole, are spaced evenly across the surface of the mold. Of course, other arrangements of holes and conduits could be used. The conduits are sealed to the manifold so that any fluid pumped into the mold through the manifold will exit through the holes in the upper surface of the mold.

(13) As shown in FIG. 10, the manifold 6 is connected to a hose 8, which is in turn connected to a three way diverter valve 9. The valve 9 is in turn connected to a vacuum pump 10 when in a first position and to a source of chilled fluid 11 (in this example a pressurized bottle of liquid nitrogen) when in a second position. In a third position the manifold may be connected to a source of positive pressure 12. A handle (not shown) allows an operator to operate the valve, although this could be automated by connecting the valve to a suitable computer controlled actuator.

(14) To use the mold 2, it is placed on a level surface as shown in FIG. 4 in a chilled room. The operator then loosely places a sheet of release material 20 across the upper surface as shown in FIG. 5. The diverter valve 9 is then operated to apply a vacuum to the manifold 6. This in turn sucks out the air between the sheet 20 and the upper surface of the mold by sucking air out of the conduits 7 so that the release material closely follows the contours of the upper surface. This is shown in FIG. 6. The valve 9 could be opened before the sheet is placed on the surface if preferred.

(15) In a next step, the preform material 30 is pressed into the mold onto the release sheet as shown in FIG. 7. This material will typically comprise sheets of carbon fibers or other elongate fibers along with an uncured or partially cured resin material. The resin material may be impregnated into the fibers before laying up, a so called prepreg material. Alternatively or additionally resin may be added to the fiber material during the laying up process.

(16) Many layers may be added, depending on the properties of the finished article. A pattern would be provide for the operator to follow if the part is complex, and the fiber sheets maybe cut prior to laying up in accordance with the pattern. The orientation of the fibers in each layer will typically also be carefully controlled as part of this process.

(17) When lay up is complete the assembly will look as shown in FIG. 7 with the material firmly pushed into place. This lay up process may be performed manually but a robot could be used to add the material. Where required, the material may be precut to the correct shape for its role in the finished article.

(18) Once the material has been layed up, the mold is then chilled by applying the liquid nitrogen to the conduits at low pressure as shown in FIG. 8. This rapidly chills the underside of the material 30, freezing it or partially freezing it. This makes the preform rigid so that it will not lose its form when removed from the mold.

(19) In a final step, the pressure applied to the underside of the release sheet 20 is increased to cause it to pop out of the mold. This is shown in FIG. 9. The preform 30, optionally with the release sheet still in place, is then gripped by a vacuum attachment on a robot arm where it is moved across into a second mold in which it will be pressed and heated to form the final cured article. The robot and attachment are shown in FIG. 10.

(20) The skilled person will understand that various modifications can be made within the scope of the present invention. In particular, the shape of the mold and number and position of holes or grooves can be varied depending on the product being produced. It is also envisaged that the mold could include multiple areas that are each shaped to a part to be produced, thus allowing more than one part to be layed up in the mold at any given time.