Abstract:
A method of moulding includes placing reinforcing fibre between a mould surface and a flexible diaphragm, and causing upward movement of the diaphragm to produce a resin flow channel along which resin is caused to flow.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority under 35 USC §119 to British Patent Application No. 1609476.5 filed on May 31, 2016 and British Patent Application No. 1615871.9 filed on Sep. 19, 2016. Both applications are hereby incorporated by reference in their entirety. 
       TECHNICAL FIELD 
       [0002]    This invention relates to a method of moulding with liquid resin. 
         [0003]    It is an object of the present invention to provide an improved method of moulding with liquid resin, particularly one which includes assisting resin infusion/injection into reinforcing fibre or other less permeable material. 
       SUMMARY OF THE INVENTION 
       [0004]    According to the present invention there is provided a method of moulding which includes placing reinforcing fibre between a mould surface and a flexible diaphragm, and causing upward movement of the diaphragm to produce a resin flow channel along which resin is caused to flow. 
         [0005]    A reusable element formed with a plurality of resin flow channels may be positioned beneath the flexible diaphragm. 
         [0006]    The reusable element may be in the form of a disc with the resin flow channels formed in the upper surface thereof. The periphery of the disc may be chamfered. 
         [0007]    A spigot and socket arrangement may be employed for holding the disc in the required position. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1A  is a schematic sectional view of the moulding system prior to the commencement of a moulding operation, 
           [0009]      FIG. 1B  shows the connection of a pipe to the chamber of the moulding system, 
           [0010]      FIG. 1C  shows a stage in the moulding operation, 
           [0011]      FIG. 2  is a plan view of a reusable rubber disc, 
           [0012]      FIG. 3  is a sectional view of the rubber disc along the line A-A of  FIG. 2 , and 
           [0013]      FIG. 4  is a sectional view showing the rubber disc in position during a moulding operation. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0014]      FIG. 1A  shows a flexible, reusable morph resin runner  1  placed on top of a mould  6  having an upwardly presented moulding surface  7 . The runner  1  includes a chamber  2  the lower boundary wall of which is afforded by a chamber diaphragm  3  having a downwardly presented resin moulding (or morph) surface  4 . The resin runner  1  is manufactured in suitable lengths and is placed on top of a stack of fibre reinforcement layers  5  sitting on the moulding surface  7 . 
         [0015]    The arrangement shown in the drawings is extended and sealed at both ends so that a vacuum may be applied and maintained in the fibre layers  5  between the moulding surface and the morph surface  4 . The connection to the vacuum pump (not shown) is via a vertical duct  9  the upper end of which is at point  8  of the face mould  6 . 
         [0016]      FIG. 1B  shows a vertically extending pipe  10  connected to the chamber  2  and, once a vacuum has been applied to the fibre reinforcement layers via pipe  9 , a vacuum is applied to the morph chamber  2  via the pipe  10 . As the pressure applied to the upper surface of the chamber diaphragm  3  is the pressure applied to the lower surface of the chamber diaphragm  3 , the diaphragm  3  will remain flat, as shown in  FIG. 1B , resting on top of the fibre layers  5 . 
         [0017]      FIG. 1C  shows a resin supply pipe  11  positioned in close proximity to the diaphragm  3 . The lower end  12  of the inlet pipe  11  is so shaped at  13  as to permit the flow of resin down the inlet pipe  11  over the fibre layers  5  into the space beneath the morph diaphragm  3 . At this crucial stage in the procedure, the pressure P 2  of the incoming resin is substantially greater than the vacuum pressure P 1  in pipes  10  and  11 . As a result, the pressure of the incoming resin exerts a force upon the close surroundings. This force results in upward deflection of the diaphragm  3  into the free space within the chamber  2  so that the diaphragm  3  has the configuration shown in  FIG. 1A .This results in the formation of a passage or channel  14  beneath the diaphragm  3  and above the fibre layers  5 . This channel  14  will extend for the length of the morph. 
         [0018]    Thus, as resin continues to flow down the supply pipe  11  under the pressure P 2 , the channel  14  will remain open as the pressure within the channel  14  remains substantially uniform, being spread by the hydraulic nature of the resin. It is to be appreciated that the fibre layers  5  present a much reduced flow passage to the resin feed. This, therefore, allows the inlet pressure P 2  to back up and continue to force the most remote ends of the diaphragm  3  upwardly. Thus, the pressure P 2  of the incoming resin actually opens up the channel  14  at a progressive rate depending on the permeability of the fibre layers  5 , the resin viscosity and the pressure difference, i.e. P 2 -P 1 . 
         [0019]    Once the mould has been filled to the required extent, the supply of resin to the inlet pipe  11  is stopped and the vacuum connection to pipe  10  is removed. P 1  returns to atmospheric pressure and, as a result, the flexible diaphragm  3  is no longer being pushed upwardly and gradually returns to its formed flat position, as shown in  FIG. 1B . This takes time, i.e. the time taken to push the necessary volume of resin out of the channel  14 . The time taken to do this can be reduced using controlled increased external pressure applied to the inlet pipe  10 . Once the passage or channel  14  has been emptied, the external pressure can be removed leaving pipe  10  open to atmospheric pressure. 
         [0020]    As described above, resin is caused to flow over and into dry reinforced fibre layers without producing any post-moulding witness of the resin transport lines or potential resin-rich cure exothermic distortions. 
         [0021]      FIGS. 2 and 3  show a reusable rubber disc  20  which, during a moulding operation, is placed on top of fibre mats  21  which, in turn, sit on top of a mould  22 . The disc  20  has an upper surface  23  and a lower surface  24 . The edge of the disc  20  is chamfered or inclined, as indicated at  25 , so that there is a variation in thickness of full thickness to zero thickness. The disc  20  has a flat, full thickness central portion  26  in which is formed an almost circular recess and five equi-angularly spaced elongated recesses  27  that extend from one side of the recess within which there is a point indicated as  28  in  FIG. 2 . The recesses  27  have a substantially uniform depth as indicated at  29  in  FIG. 3 . 
         [0022]    The rubber disc  20  is placed beneath a reusable vacuum membrane  30  with the resin entry point in direct alignment with point  28  and with the elongated recesses  27  coinciding with and crossing the membrane “Morphflo” channel as explained above with reference to  FIGS. 1A, 1B and 1C . 
         [0023]    The reusable vacuum membrane  30  is always produced with an adjacent resin inlet insert located as close as possible to the moulded “Morphflo” channels so that the channels  27  in the rubber disc  20  direct the incoming resin under the reusable membrane  30  and over the fibre mats  21 . The dimensions of the channels  27  and the number thereof are such that there is substantially no resin flow restriction. The reusable membrane  30  has a surface  31  which, under the vacuum conditions within the fibre mats  21  sitting on top of the mould  22 , is distorted to form a negative shape, as indicated at  32 , over the disc  20 . During a moulding operation, i.e. during the flow of resin under pressure, the surfaces  24  and  31  are maintained level and a level moulding surface is thus produced. There is thus no witness of resin entry in the cured resin moulding. 
         [0024]    The rubber disc  20  formed with recesses may be referred to as a “Crowsfoot” disc and its peripheral configuration and thickness may be varied from that shown in the drawings. Positioning sockets may be built into the membrane  30  to hold the “Crowsfoot” disc  20  in the required position. 
         [0025]    It is also possible to use a “Crowsfoot” disc  20  in a moulding operation in which the reusable membrane  30  is replaced by conventional consumable bag material. 
         [0026]    A modification to the above design of “Crowsfoot” disc enables this general procedure to be used as a horizontal cross-over flow channel between two separate “MorphFlo” channels, thus providing unlimited multi-“MorphFlo” stand-alone sealed channels that permit resin cross-over from one to the other. 
         [0027]    In the arrangement shown in  FIGS. 2 to 4 , the disc  20  is placed upon the fibre mats  21  and allows the resin to enter a standard hole fitting in the membrane  30  and to be diverted at  90  degrees across the fibre pack and reach the morph section which has a vacuum equal to that of the fibre pack. As the pressure of the resin is at or close to atmospheric pressure, this forces the morph flow section upwards to open the morph flow channel above the fibre pack. 
         [0028]    This allows the resin to enter the mould cavity along predefined routes and, when injection of the resin is complete, the morph is made to flatten to the fibre pack thus eliminating any post-cure resin flow marks. The “Crowsfoot” cross-flow remaining cured resin is isolated from the infused and cured fibre pack thus ensuring that no cured resin remains upon the face of the moulded component.