Patent TW-576789-B (TW)
Title: Device for applying closing force in injection molding machine in particular for producing shoe
Inventor: KRAEMER RUDOLF
IPC: B29C45/67
Filed: 2002-06-26
Granted: 2004-02-21
Abstract: Disclosed is a force application device for applying a mold closing force in an injection molding machine. The injection molding machine is particularly for producing shoe and sole and comprises at least one mold tool for producing the sole to be produced or formed. The mold tool is comprised of a side mold portion, a bottom pressing mold that is vertically movable, and an ejector or a last forming portion, the last being provided with a boot portion and serving to delimit a mold cavity. The force application device comprises a piston-cylinder device (tool base punch cylinder) for moving the tool base punch. The piston-cylinder device comprises two separate chambers, wherein a piston is movable in the first chamber. The piston is fed on both sides with compressed air. A second piston is movable in the second chamber. The second piston is fed on one side with a hydraulic pressure medium. The two pistons are securely connected to each other. The hydraulic pressure medium can be driven into the second chamber from a storage tank in communication with the second chamber and flows from the second chamber back into the storage tank by using the pneumatic pressure. The force application device further comprises a force amplifying cylinder to generally apply the closing force. The above described is the conventional portion following the prior art. To improve, two modifications are suggested, of which the first one combines the storage tank (20) with the force amplifying cylinder (19). The force amplifying cylinder (19) is comprised of two separate chambers (20)(21) and a piston (23) that are fed on both sides thereof with compressed air being movable in one of the two chambers (20)(21). The piston (23) has a piston rod (24) extending into the second chamber (20). The storage tank has a cross-section reduced section (26) in the direction toward an end of the piston rod. By means of the reduced section, the piston rod (24) is allowed to move into a portion of the storage tank to seal the reduced section. A portion of the storage tank is located in the side of the reduced section (26) that is in communication with the second chamber (14) of the tool base punch (8) via a connection (40). A hydraulic fluid pipe (25) is open into the portion of the storage tank (20) located below the reduced section (26) and the hydraulic fluid pipe (25) extends from an accumulator (36). The accumulator (36) exhibits an overpressure. The force amplifying cylinder (19) is flange-coupled to a casing of the tool base punch (8). The chamber (20) is integrated with a wall of the casing of the tool base punch (8). Piping connecting to the second chamber (12)(14) of the tool base punch (8) is reduced to a single hole (40) defined in the casing wall. In the second modification, the tool base punch cylinder is integrated with a force amplifying cylinder as a single unit (45). The unit (45) has two separate cylinder chambers (46)(47), wherein the piston (53) that is fed on both sides with compressed air is received in one (46) of the chambers. The piston (53) has a piston-like extension (52) in the direction along the second chamber (46). The extension is moveable in an opening (51). The opening (51) connects both chambers (46)(47) to form a storage tank. The piston (49) that is hydraulically fed on one side is arranged in another chamber (46), wherein the side that is fed on pressure is connected to the opening (5) and the line (56) that supplies the hydraulic pressure medium from the accumulator (54) is opened to a location below the opening (51).