초록 ▼

The invention relates to hard sided luggage shells and other containers manufactured using vacuum forming or pressure forming of thermoplastics. A process for making shells and containers with integrally molded frames is disclosed, and products made by the method. A method of manufacturing different

The invention relates to hard sided luggage shells and other containers manufactured using vacuum forming or pressure forming of thermoplastics. A process for making shells and containers with integrally molded frames is disclosed, and products made by the method. A method of manufacturing differential pressure formed containers with framed openings, but without the need to attach a separate frame element to the molded shell. A process also is disclosed for reducing the undesirable stretching of shell material that occurs during differential pressure forming, particularly the thinning of corner portions of the shell or container. The process of the invention more efficiently utilizes the thermoplastic material by moving material from otherwise offal portions into the molded product. An improved method for severing the offal material from the final product is disclosed.

대표청구항 ▼

[ We claim:] [1.] A process for molding a shell from a sheet of plastic material, the shell having a bottom and side portions extending from the bottom to a peripheral edge, the intersection of two side portions and the bottom generally defining a shell corner, the process comprising the steps of:(a

[ We claim:] [1.] A process for molding a shell from a sheet of plastic material, the shell having a bottom and side portions extending from the bottom to a peripheral edge, the intersection of two side portions and the bottom generally defining a shell corner, the process comprising the steps of:(a) heating the sheet of plastic material, the sheet having a central portion, a marginal portion, and a selvage portion;(b) providing a mold means having a mold surface of a shape corresponding to the shell;(c) providing a form space defined in part by the mold surface;(d) providing at least one movable side draw form extending into the form space;(e) positioning the central portion of the sheet in the mold means opposite the mold surface;(f) providing a clamp remote from the mold surface;(g) clamping the selvage portion of the sheet;(h) disposing four rigid, upwardly extending, corner plugs within the form space;(i) contacting the sheet with the four corner plugs and deliberately allowing the sheet to droop and sag by gravity between all four plugs to pre-stretch the central portion of the sheet;(j) allowing the heated sheet to slide inwardly over the four corner plugs and into the form space prior to forcing the central portion against the mold surface;(k) conforming the central portion of the sheet to the mold surface to form the bottom and the side portions of the shell;(l) forcing the marginal portion of the sheet against the side draw form, thereby shaping the marginal portion to fashion a frame integrally formed with the central portion, said frame extending substantially continuously along at least one of the side portions of the shell, and said frame comprising a wall member and a flange, said forcing step comprising:bending the marginal portion to form the wall member extending into the form space from the side portion of the shell; andfashioning the flange so that said flange extends from the wall member to the selvage portion and is disposed at an angle with respect to the wall member and to the selvage portion;(m) laterally retracting the side draw form to a retracted position substantially outside the form space;(n) only after laterally retracting the side draw form, removing the shell from the mold surface; and(o) severing the selvage portion of the sheet from the flange to free an edge of the flange whereby, after the step of severing, the peripheral edge is defined by the free edge of the flange.