Continuous molding conveyor with side clamping and release

Abstract

Plastic is foamed in a pressure tunnel portion of a molding conveyor formed by opposed endless conveyor runs with side pieces defining the product cross section. One or both employed the endless runs, preferably the bottom conveyor run is laterally split into at least two separate endless shiftable conveyors respectively carrying the side pieces forming the sides of the pressure tunnel, which shiftable conveyors are laterally movable, with respect to the conveying or molding direction, at the tunnel entrance and the tunnel exit for clamping and unclamping respectively, that is for bringing the side pieces horizontally toward each other transverse to the molding direction to form the final configuration for the tunnel cross section and away from each other at the molding tunnel exit to release the sides of the molded product. This clamping and unclamping of the side pieces is particularly important with molded sheets having a configured edge so that the side pieces may be constructed with a corresponding configuration. Preferably, the two shiftable endless conveyors are constructed of a series of plates having pivotal connections therebetween to form a chain, which connections will allow additional sliding or shifting of the plates with respect to each other within a limited range, preferably under the control of guide means on the individual plates and stationary support structure. Preferably, the guide means are rollers on the plates engaging within stationary tracks. A flexible cover endless belt may be employed to bridge the joint between the shiftable endless conveyors and form the entire bottom surface for the tunnel portion. After the lower shiftable conveyors have been moved toward each other to their final tunnel configuration, a flexible endless belt may be tightly brought into contact with the tops of the side pieces and clamped by the upper rigid endless conveyor, so that through the unsupported tunnel portion, the upper belt will be tightly held at its opposite ends and not subject to sagging while forming a smooth continuous upper wall for the molding pressure tunnel.

What is claimed is: 
     
       1. Apparatus for the continuous molding of a product, comprising a first endless molding conveyor means, and a second opposed endless molding conveyor means having adjacent runs through a molding zone; said first conveyor means acting as a cover belt to said second conveyor means in said molding zone, said second conveyor means being longitudinally split into at least two generally aligned endless conveyors; at least one of said separate endless conveyors having a side flange within the molding zone closing the corresponding side space between said first and second conveyor means; and means shifting said at least one of said separate endless conveyors and side flange laterally, with respect to the conveying direction in the molding zone, toward the other of said separate endless conveyors at the upstream end of the molding zone, and shifting said at least one of said separate endless conveyors and its side flange away from the other of said separate endless conveyors at the downstream end of the molding zone. 
     
     
       2. The apparatus of claim 1, wherein said other of said separate endless conveyors includes a second side flange within the molding zone closing the corresponding side space between said first and second conveyor means along the side of the apparatus opposite from the first-mentioned side flange at least within the molding zone. 
     
     
       3. The apparatus of claim 2, including further means shifting said other of said separate endless conveyors and its side flange laterally toward said one of said separate endless conveyors at the upstream end of said molding zone and laterally away from said one of said separate endless conveyors at the downstream end of said molding zone. 
     
     
       4. The apparatus of claim 3, wherein said separate endless conveyors are constructed of a plurality of links having limited lateral movement with respect to each other; said shifting means having roller means on said links with axes perpendicular to the direction of conveyor travel through the molding zone and the lateral direction, and stationary converging, diverging track means receiving therein said rollers. 
     
     
       5. The apparatus of claim 4, wherein said conveyor links include flat base plates having opposite end return bend flanges, and C-shaped connecting members each engaging within adjacent return bend flanges; and each of said links having means on opposite sides of said C-shaped members spaced apart a greater distance than the length of said C-shaped members for providing a limited range of shifting movement of said links laterally with respect to each other. 
     
     
       6. The apparatus of claim 2, including a single flexible cover sheet overlying the molding surface of said first endless molding conveyor means, at least within the molding zone, and being clamped along its opposite edge portions between said side flanges and said first endless molding conveyor means. 
     
     
       7. The apparatus of claim 6, including means feeding said single flexible cover sheet at an angle to the conveying direction at the upstream end of the molding zone into engagement with the adjacent surfaces of said side flanges and providing a rotatable support changing the angle of feed to that of the conveying direction to provide a stretched laterally straight flexible cover sheet immediately prior to clamping; and said side flanges and first endless molding conveyor means maintaining said single flexible cover sheet in its clamped position throughout the molding zone. 
     
     
       8. The apparatus of claim 7, wherein said separate endless conveyors and their carried side flanges are shifted laterally slightly away from each other after clamping said single flexible cover sheet to tightly stretch the flexible cover sheet laterally; and said separate endless conveyors remaining slightly spaced from each other throughout the molding zone to maintain the stretched condition of said flexible cover sheet within the molding zone. 
     
     
       9. The apparatus of claim 8, wherein the surfaces of said side flanges engaging said flexible cover sheet are roughened to provide a friction surface for gripping the side edges of the upper flexible cover belt. 
     
     
       10. The apparatus of claim 1, including a single, flexible cover sheet overlying the molding surface of each of said separate endless conveyors and spanning the joint therebetween. 
     
     
       11. The apparatus of claim 1, wherein said one separate endless conveyor is constructed of a plurality of links having limited lateral movement with respect to each other; said shifting means having roller means on said links with axes perpendicular to the direction of conveyor travel through the molding zone and the lateral direction, and stationary converging, diverging track means receiving therein said rollers. 
     
     
       12. The apparatus of claim 11, wherein said conveyor links include flat base plates having opposite end return bend flanges, and C-shaped connecting members each engaging within adjacent return bend flanges; and each of said links having means on opposite sides of said C-shaped members spaced apart a greater distance than the length of said C-shaped members for providing a limited range of shifting movement of said links laterally with respect to each other. 
     
     
       13. Apparatus for the continuous molding of a product, comprising: a first endless molding conveyor means having a conveyor run; a second opposed endless molding conveyor means having a conveyor run adjacent the corresponding conveyor run of said first endless molding conveyor means said first conveyor means acting as a cover belt to said second conveyor means in said molding zone; opposed side piece means forming with said first and second endless molding conveyor means runs a substantially closed molding tunnel; means drivingly interconnecting at least one of said side piece means and at least a portion of one of said endless molding conveyor means at least along said runs; and means shifting said at least one portion of said one endless molding conveyor means and its side piece means laterally, with respect to the conveying direction in the molding tunnel, toward the other of said side piece means at the upstream end of said molding tunnel, and shifting said at least one portion of said one endless molding conveyor means and its side piece means away from the other of said side piece means at the downstream end of the molding tunnel. 
     
     
       14. The apparatus of claim 13, wherein said other side piece means is drivingly interconnected with at least one portion of said other endless molding conveyor means; and means shifting said at least one portion of said other endless conveyor means and its side piece means laterally toward the one of said side piece means at the upstream end of said molding tunnel, and shifting said at least one portion of said other endless molding conveyor means and its side piece means away from the one of said side piece means at the downstream end of the molding tunnel. 
     
     
       15. The apparatus of claim 14, wherein each of said endless molding conveyor means is a single endless belt conveyor. 
     
     
       16. The apparatus of claim 15, wherein each single endless belt is composed of a plurality of rigid plates extending substantially the full lateral width of the belt and edge interconnected in a chain with lateral shifting lost motion. 
     
     
       17. The apparatus of claim 16, wherein said shifting means includes fixed guide tracks, and rollers secured to said plates and guidingly received within said tracks. .Iadd.18. Apparatus for the continuous molding of a product, comprising a first endless molding conveyor means, and a second opposed endless molding conveyor means having adjacent runs through a molding zone; said first conveyor means acting as a cover belt to said second conveyor means in said molding zone, said second conveyor means being longitudinally split into at least two generally aligned endless conveyors; at least one of said separate endless conveyors having a side flange within the molding zone closing the corresponding side space between said first and second conveyor means; and means shifting said at least one of said separate endless conveyors and side flange laterally, with respect to the conveying direction in the molding zone, relative to the other of said separate endless conveyors at one of the downstream end and upstream end of the molding zone. .Iaddend..Iadd.19. The apparatus of claim 18, wherein said other of said separate endless conveyors includes a second side flange within the molding zone closing the corresponding side space between said first and second conveyor means along the side of the apparatus opposite from the first-mentioned side flange at least within the molding zone; and further means shifting said other of said separate endless conveyors and its side flange laterally at said one of the downstream end and upstream end of said molding zone. .Iaddend..Iadd.20. The apparatus of claim 19, wherein said separate endless conveyors are constructed of a plurality of links pivotally connected together in one endless chain for limited lateral movement with respect to each other; said shifting means having roller means on said links with axes perpendicular to the direction of conveyor travel through the molding zone and the lateral direction, and stationary converging, diverging track means receiving therein said rollers. .Iaddend. .Iadd.21. The apparatus of claim 20, wherein said conveyor links include flat base plates having opposite end return bend flanges, and C-shaped connecting members each engaging within adjacent return bend flanges; and each of said links having means on opposite sides of said C-shaped members spaced apart a greater distance than the length of said C-shaped members for providing a limited range of shifting movement of said links laterally with respect to each other. .Iaddend..Iadd.22. The apparatus of claim 18, including a single, flexible cover sheet overlying the molding surface of each of said separate endless conveyors and spanning the joint therebetween. .Iaddend..Iadd.23. The apparatus of claim 18, wherein said one separate endless conveyor is constructed of a plurality of links having limited lateral movement with respect to each other; said shifting means having roller means on said links with axes perpendicular to the direction of conveyor travel through the molding zone and the lateral direction, and stationary converging, diverging tracks means receiving therein said rollers. .Iaddend..Iadd.24. The apparatus of claim 23, wherein said conveyor links include flat base plates having opposite end return bend flanges, and C-shaped connecting members each engaging within adjacent return bend flanges; and each of said links having means on opposite sides of said C-shaped members spaced apart a greater distance than the length of said C-shaped members for providing a limited range of shifting movement of said links laterally with respect to each other. .Iaddend..Iadd.25. The apparatus of claim 18, wherein said one conveyor side flange includes an undercut configured surface, as seen in cross-section perpendicular to the conveying direction, facing the interior of the molding zone; said shifting means laterally moving said one conveyor side flange at the downstream end an amount greater than the depth of said undercut portion so that said side flange can move in the endless path of its conveyor and clear a rigid product molded in said undercut portion. .Iaddend..Iadd.26. Apparatus for the continuous molding of a product, comprising: a first endless molding conveyor means having a conveyor run; a second opposed endless molding conveyor means having a conveyor run adjacent the corresponding conveyor run of said first endless molding conveyor means, said first conveyor means acting as a cover belt to said second conveyor means in said molding zone; opposed side piece means forming with said first and second endless molding conveyor means runs a substantially closed molding tunnel; means drivingly interconnecting at least one of said side piece means and at least a portion of one of said endless molding conveyor means at least along said runs; and means shifting said at least one portion of said one endless molding conveyor means and its side piece means laterally, with respect to the conveying direction in the molding tunnel, with respect to the other of said side piece means at one of the upstream end of said molding tunnel and the downstream end of the molding tunnel. .Iaddend..Iadd.27. The apparatus of claim 26, wherein said other side piece means is drivingly interconnected with at least one portion of said other endless molding conveyor means; and means shifting said at least one portion of said other endless conveyor means and its side piece means laterally at said one of said upstream end of said molding tunnel and said downstream end of the molding tunnel. .Iaddend..Iadd.28. The apparatus of claim 27, wherein each of said endless molding conveyor means is a single endless belt conveyor. .Iaddend. .Iadd.29. The apparatus of claim 28, wherein each single endless belt is composed of a plurality of rigid plates extending substantially the full lateral width of the belt and edge interconnected in a chain with lateral shifting lost motion. .Iaddend..Iadd.30. The apparatus of claim 29, wherein said shifting means includes fixed guide tracks, and rollers secured to said plates and guidingly received within said tracks. .Iaddend..Iadd.31. The apparatus of claim 26, wherein said one side piece means includes an undercut configured surface, as seen in cross section perpendicular to the conveying direction, facing the interior of the molding zone; said shifting means laterally moving said one conveyor side piece means at the downstream end an amount greater than the depth of said undercut portion so that said side piece means can move in the endless path of its conveyor and clear a rigid product molded in said undercut portion. .Iaddend.