Process for vacuum forming a stud plate from a plastic sheet
OwnerHeinrich Wischemanninventor
Life of this patent
Estimating the term…
Abstract
A process for producing a stud plate from plastic by vacuum forming uses a positive mold (21) in which these is held on the end face (32) of each stud (28), a flexible elastic disc which protrudes with a part (45) of its flexible length over the edge. A projection (22, 24) of a hollow stud is formed thereon. During demolding a part (44) of the disc lying radially further inwards bends upwards from the end face, so that the protruding part (45) yields and readily slides along the inner wall (49) of the previously molded hollow stud (11).
Claims20
Process for vacuum forming from a plastic sheet a stud plate having hollow studs standing up from a base plate at pre-determined positions, each hollow stud being provided with an inner wall and an upper circumferential edge with at least one radially protruding projection, comprising:
- using positive molds (26), each having an associated mold stud (28) with a molding side, including an upper end face (32), on which said hollow studs are formed, fixing and holding down a center part (38) of a flexible elastic disc (33) in continuous contact with said upper face (32) on said molding side of said associated mold stud (28) by fixing means (41, 42), said fixing means being accessible to fix and hold down said center part (38) from said molding side of said mold studs (28), said fixing means fixing and holding down said center part (38) in continuous contact with said upper end face (32) in a direction opposite to the direction in which said plastic sheet (46) is pulled from said mold studs (28) following vacuuming forming,
- forming said at least one projection by means of said disc (33), said disc (33) having a flat, lower side and an upper side, said disc (33) being held with a first part (44) of said flat, lower side lying flat and loosely on said upper end face (32) and projecting with a second part (45) of said flat, lower side, continuous with said first part (44), beyond a circumferential edge of said upper end face (32), said disc (33) having a flexural rigidity such that said second part (45) remains extended substantially beyond said circumferential edge of said upper end face (32) when said plastic sheet (46) is drawn over said mold studs (28), and such that at least said first part (44) bends upwards from said upper end face (32) when said hollow stud (11) is pulled upwards from said mold studs (28),
- drawing said plastic sheet (46) over said mold studs (28) by vacuum to form said at least one projection (21, 22, 23, 24) and
- pulling said hollow stud (11) upwards from said mold stud (28), said second part (45) sliding along said inner wall (49) of said hollow stud (11),
- wherein said positive mold has at least one base plate (63, 64, 65,75) in the form of at least a section of a cylindrical barrel from which said mold studs (28) project radially outwards towards said molding side of said mold studs.
Dependencies are inferred from the claim text.