Heat-sealing apparatus

Abstract

A heat-sealing apparatus comprising a pair of opposed hot plates and a pair of hot plate-mounting blocks to which said hot plates are mounted, respectively. The hot plates respectively have pressing surfaces adapted to be pressed against each other with superimposed film sheets held therebetween during sealing; and mounting surfaces formed at opposite sides to said pressing surfaces. The hot plate-mounting blocks respectively have support surfaces. The hot plates are mounted to said hot plate-mounting blocks in such a manner that the mounting surfaces are pressed against the support surfaces, and that the hot plates can thermally expand and contract in a sealing direction without being restrained by said hot plate-mounting blocks. In another aspect of the invention, the mounting surfaces are formed on respective surfaces extending substantially perpendicular to the pressing surfaces and the hot plates are mounted on respective support surfaces formed on the hot plate-mounting blocks.

1 . A heat-sealing apparatus comprising:
 a pair of opposed hot plates; and   a pair of hot plate-mounting blocks to which said hot plates are mounted, respectively;   wherein superimposed film sheets are pressed between said hot plates to thermoweld them together;   said hot plates respectively comprising:   pressing surfaces adapted to be pressed against each other with said film sheets held therebetween during sealing; and   mounting surfaces formed at opposite sides to said pressing surfaces;   said hot plate-mounting blocks respectively comprising support surfaces that retain said mounting surfaces, respectively;   wherein said hot plates are mounted to said hot plate-mounting blocks in such a manner that said mounting surfaces are pressed against said support surfaces, and that said hot plates can thermally expand and contract in a sealing direction without being restrained by said hot plate-mounting blocks.   
     
     
         2 . The heat-sealing apparatus of  claim 1 , wherein a constituent material of said hot plates and a constituent material of said hot plate-mounting blocks differ in thermal expansion coefficient from each other. 
     
     
         3 . The heat-sealing apparatus of  claim 1 , wherein said hot plates are retained by said support surfaces at a part of said mounting surfaces. 
     
     
         4 . The heat-sealing apparatus of  claim 1 , wherein said hot plates are formed so that said pressing surfaces are concavely or convexly curved in a horizontal plane at an ordinary room temperature, and said pressing surfaces become flat when said hot plates are heated to a predetermined sealing temperature. 
     
     
         5 . The heat-sealing apparatus according to  claim 1 , wherein said hot plate-mounting blocks comprise guide portions that abut against said hot plates to position said hot plates in a vertical direction. 
     
     
         6 . The heat-sealing apparatus according to  claim 1 , further comprising:
 adjustment pins provided for said hot plate-mounting blocks, respectively, said adjustment pins each comprising:   a mounting shank portion mounted to an associated one of said hot plate-mounting blocks in such a manner that a position thereof in a rotational direction is adjustable; and   an eccentric shank portion that is eccentric with respect to said mounting shank portion and that extends toward an associated one of said hot plates;   said mounting surfaces of said hot plates comprising slots elongated in the sealing direction, each of said slots being capable of accommodating said eccentric shank portion.   
     
     
         7 . The heat-sealing apparatus of  claim 1 , wherein said hot plates are each secured to one end of each of a plurality of shaft-shaped members spaced in the sealing direction and inserted through respective holes formed in the associated one of said hot plate-mounting blocks, said shaft-shaped members being urged by urging members toward the other ends thereof, wherein at least all but one of said shaft-shaped members are provided with clearances in said holes at least in said sealing direction. 
     
     
         8 . The heat-sealing apparatus of  claim 7 , further comprising:
 fall-preventing plates that prevent movement of said shaft-shaped members away from said hot plates.   
     
     
         9 . The heat-sealing apparatus according to  claim 1 , wherein said hot plates are each fixedly secured to an associated one of said hot plate-mounting blocks at one portion thereof, said heat-sealing apparatus further comprising:
 one or more shaft-shaped members provided for each combination of each of said hot plates and an associated one of said hot plate-mounting blocks, said one or more shaft-shaped members being spaced in the sealing direction and each mounted at one end thereof to either one of said hot plate and hot plate-mounting block of said combination, the other end of each of said one or more shaft-shaped members extending toward the other of said hot plate and hot plate-mounting block of said combination and inserted into a hole formed in said the other of said hot plate and hot plate-mounting block of said combination with a clearance at least in said sealing direction.   
     
     
         10 . The heat-sealing apparatus of  claim 9 , wherein said one or more shaft-shaped members are each mounted at said one end in such a manner that a position thereof in a rotational direction is adjustable, said the other end of each of said one or more shaft-shaped members being eccentric with respect to said one end, and said hole is a slot elongated in said sealing direction. 
     
     
         11 . A heat-sealing apparatus comprising:
 a pair of opposed hot plates; and   a pair of hot plate-mounting blocks to which said hot plates are mounted, respectively;   wherein superimposed film sheets are pressed between said hot plates to thermoweld them together;   said hot plates respectively comprising:   pressing surfaces adapted to be pressed against each other with said film sheets held therebetween during sealing; and   mounting surfaces formed on respective surfaces extending substantially perpendicular to said pressing surfaces;   said hot plates being mounted on respective support surfaces formed on said hot plate-mounting blocks.   
     
     
         12 . The heat-sealing apparatus of  claim 11 , wherein a constituent material of said hot plates and a constituent material of said hot plate-mounting blocks differ in thermal expansion coefficient from each other.