Work holders – Relatively movable jaws – Means to actuate jaw
Reexamination Certificate
1999-12-03
2001-03-20
Gerrity, Stephen F. (Department: 3723)
Work holders
Relatively movable jaws
Means to actuate jaw
C269S216000, C269S217000, C269S275000, C269S286000
Reexamination Certificate
active
06202998
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an apparatus for supporting a thermoformable material along its peripheral edges for automated transfer before and after preheating operations prior to thermoforming and during forming in a mold cavity.
BACKGROUND ART
A prior art method of preheating a thermoformable material, including thermoset and thermoplastic materials, involves contact heating. The contact heating method includes placing the material in direct contact with a heat source, such as thermally regulated upper and lower platens. Heat is then transferred principally by conduction from the outer surface to the inner core of the material. Because such materials are typically poor conductors of heat, however, this method requires a significant amount of time to sufficiently heat the materials.
Another method of preheating a thermoformable material involves radiant heating. This method involves placing the material near a radiant heat source, such as electric coils or ceramic heaters. The outer portions of the material, however, tend to selectively absorb the radiant energy, and core heating is again accomplished primarily by conduction. Consequently, this method also requires a significant amount of time to sufficiently heat the material.
A significant improvement over prior art methods of preheating a thermoformable material is described in commonly owned U.S. patent application Ser. No. 09/082,743, entitled “Method And Apparatus For Preheating Permeable, Thermoformable Material”, which is hereby incorporated by reference in its entirety. This application provides a method and apparatus for preheating a permeable, thermoformable material having first and second sides, and includes a housing and first and second retaining members cooperable with each other to sufficiently retain the material within the housing. A fluid distribution system is disposed within the housing and is adapted to be connected to a source of heated fluid. The fluid distribution system is operative to introduce heated fluid onto the first side of the material. In addition, the housing is adapted to cooperate with a negative pressure source for developing a suction on the second side of the material to draw the heated fluid through the material, thereby convectively heating the material. In this design, the thermoformable material is held along its peripheral edges by a plurality of screws or nails which are supported on a frame. This feature requires the operator to press the thermoformable material onto the screws or nails to attach the thermoformable material to the frame, which adds labor and assembly costs to the manufacturing process, and does not lend itself to robotic handling.
Accordingly, it is desirable to provide an improved apparatus for holding the peripheral edges of the thermoformable sheet material onto a frame in a manner which is easily clamped and unclamped, and lends itself to robotic operation, and also prevents heat losses by leakage along the peripheral edges of the thermoformable sheet material.
DISCLOSURE OF INVENTION
The present invention overcomes the above-referenced shortcomings of prior art assemblies by providing an apparatus for supporting a thermoformable material along its peripheral edges which includes a frame forming a channel therein for receiving the peripheral edges, and at least one retaining arm pivotally connected to the frame for clamping the peripheral edges into the channel formed by the frame by pivoting the retaining arm past an edge of the frame for clamping the thermoformable sheet between the retaining arm and the edge. In this configuration, the retaining arm cooperates with the thermoformable material to act as an over-center spring device which clamps the peripheral edges of the thermoformable material when moved past the edge of the frame into the channel to secure the peripheral edge and prevent leakage of air blown or drawn in either direction through the thermoformable material.
More specifically, the present invention provides an apparatus for supporting a thermoformable material along its peripheral edges, including a frame forming a channel therealong for receiving the peripheral edges of the thermoformable material. The channel includes an opening formed between first and second edges of the frame. At least one retaining arm is pivotally connected to the frame along the first edge and includes a distal end. The retaining arm is pivotable between an open position to allow insertion of the peripheral edge of the thermoformable material into the channel and a closed position for clamping the thermoformable material between the distal end and the second edge.
The present invention is useful for clamping not only a thermoformable material along its peripheral edges for automated transfer before and after preheating operations prior to thermoforming and during forming in a mold cavity, but also useful in other environments for clamping a variety of sheet materials for operations thereon, such as heating, printing, etc.
Accordingly, an object of the invention is to provide an apparatus for supporting a sheet material along its peripheral edges in a manner which does not require significant handling of the sheet material for installation and removal, and in which a seal is provided along the peripheral edges of the material to prevent escape of air which is blown or drawn through the sheet material.
The above object and other objects, features, and advantages of the present invention are readily apparent from the following detailed description of the best mode for carrying out the invention when taken in connection with the accompanying drawings.
REFERENCES:
patent: 2985304 (1961-05-01), Chryst et al.
patent: 4379101 (1983-04-01), Smith
patent: 4609519 (1986-09-01), Pichard et al.
patent: 4796877 (1989-01-01), Musil et al.
patent: 4812284 (1989-03-01), Fleissner
patent: 4923555 (1990-05-01), Elliott et al.
patent: 4943222 (1990-07-01), Nathoo
patent: 5085580 (1992-02-01), Reunamaki
patent: 5108532 (1992-04-01), Thein et al.
patent: 5108691 (1992-04-01), Elliott
patent: 5575080 (1996-11-01), Fleissner
patent: 5595375 (1997-01-01), Bennhausen
patent: 5696328 (1997-12-01), Underwood et al.
patent: 5797580 (1998-08-01), Ryberg
Brooks & Kushman P.C
Gerrity Stephen F.
Lear Corporation
Wilson Lee
LandOfFree
Apparatus for supporting a sheet material along its... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Apparatus for supporting a sheet material along its..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Apparatus for supporting a sheet material along its... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2519216