Patent Publication Number: US-2002006454-A1

Title: Mold ejection apparatus for use in compression molding of cellulosic articles

Description:
CROSS REFERENCE TO RELATED APPLICATION  
     [0001] Priority is claimed from U.S. Provisional Application Ser. No. 60/188,467, filed Mar. 10, 2000. 
    
    
     
       BACKGROUND OF THE INVENTION  
       [0002] 1. Field of the Invention  
       [0003] The present invention relates generally to mold ejection apparatus for use in compression molding of cellulosic articles and, more particularly, to the molding under heat and pressure of thermosetting resin coated wood fiber furnish which has been recycled from waste wood articles and convenient ejection of the molded article from the mold.  
       [0004] 2. Description of the Related Art  
       [0005] It has long been known that synthetic products can be manufactured using a thermosetting binder, heat and pressure to reconsolidate refined cellulosic and/or lignocellulosic furnish materials into unitary rigid products. One common form of such products is particle board or fiberboard. The binders usually used in producing particle board, for example, are thermosetting resins such as urea-formaldehyde or phenol-formaldehyde. An example of a process for manufacturing such boards is disclosed in early U.S. Pat. No. 2,757,115 issued to Heritage. Basically, this patent teaches reducing a furnish material, such as wood, to fibers by a refiner, mixing the fibers with a binder and other chemicals such as release and sizing agents, forming the mixture into mats and compressing the mats between heated platens in a hot press to form board products of a desired thickness and density.  
       [0006] Waste disposal is an ever increasing concern to society. Although recycling efforts have been relatively successful with a variety of materials, certain materials have continually posed a problem as being generally non-recyclable. Examples of these hard-to-recycle materials include urban wood waste such as demolition waste from old buildings, wood chips generated from construction materials, old pallets and crates and the like. Accordingly, it is desirable to provide a process for recycling urban wood waste into useful synthetic wood-base products. Further, it is desirable to provide such a process which can produce molded articles under heat and pressure in various shapes and contours, such as, for example, chair form products for manufacturing chair seats and backs. Still further, it is desirable to provide a highly effective means for ejecting a molded article from its mold.  
       SUMMARY OF THE INVENTION  
       [0007] The present invention improves over the prior art by providing an ejection system for use with a compression molding apparatus including one or more molds each having a core member and a cavity member, wherein the core member is provided with spring biased knockout pins that are engaged by a cross member to extend the pins and release a molded article when the mold is in an open position. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWING  
     [0008] The foregoing and other novel improvements and advantages of the invention will be better understood upon a reading of the following detailed description taken in conjunction with the accompanying drawing wherein:  
     [0009]FIG. 1 is a side schematic view of a compression molding apparatus illustrating an article ejection system constructed according to the principles of the invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
     [0010] Referring now to the drawing, FIG. 1 illustrates a side schematic view of a dual mold compression molding apparatus designated generally by the reference numeral  10 . The apparatus  10  is particularly suitable for compression molding under heat and pressure, of recycled wood waste which has been ground into fibers of predetermined dimensions and mixed with a binder such as a thermosetting resin. Batches of mixed fibers and resin are delivered by any convenient means to one or more two-part molds  12  including mold cavity members  14  and mold core members  16 . The mold core members  16  are suspended from a suitable hydraulic cylinder press apparatus designated generally as  20 . Preferably, the molds  12  are heated to an appropriate elevated temperature by circulating hot oil through internal mold passages.  
     [0011] Each mold core member  16  and cavity member  14  may be designed to compress the wood fiber and resin composition into any suitable finished shape. An example of a molded article may be a formed chair seat or chair back having suitable contour such that it can be later upholstered to provide a comfortable chair product. Once the cavity member  14  is loaded with a batch of fiber and resin, the mold  12  closes and by heat and pressure the fibers are compressed into a dense mass. The resin is then allowed to cure.  
     [0012] Fitted in the core member  16  are a plurality of knock-out pins  22  which are biased by springs  24  such that the distal ends of the pins  22  are flush with the lower surface  26  of the core member  16  when the press is closed. After curing of the resin the molds  12  are opened to an intermediate position whereupon the molded article is removed from the cavity members  14  by adhering to downwardly directed pins  28  projecting from the core surface  26 . The cavity member  14  is then shuttled to the side. In accordance with the invention, a cross member  30  is located above the pins  22  in a mounting plate  32  on top of the core member  14 . As the mold  12  is further opened the cross member  30  strikes one or more stops  34  which causes the cross member to engage proximal ends of the pins  22  and extend the pins  22 , against the action of the springs, beyond the surface  26  of the core member  16  thereby urging the molded article to dislodge from the pins  28  and separate from the core member  16 . The molded article then drops onto a table  36  whereupon it can be removed by any convenient means.  
     [0013] It can now be appreciated that the ejection system of the present invention provides a highly effective and efficient means of ejecting a molded article from a press. Particularly where heated molds are employed the ejection system of the present invention is considerably effective, as opposed to prior art ejection means, in reducing undesirable heat transfer from the molds.  
     [0014] While the present invention has been described in connection with preferred embodiments thereof, it will be apparent to those skilled in the art that many changes and modifications may be made without departing from the true spirit and scope of the invention. Accordingly, it is intended by the appended claims to cover all such changes and modifications as come within the spirit and scope of the invention.