Plastic and nonmetallic article shaping or treating: processes – Mechanical shaping or molding to form or reform shaped article – Shaping against forming surface
Patent
1993-09-21
1996-03-05
Timm, Catherine
Plastic and nonmetallic article shaping or treating: processes
Mechanical shaping or molding to form or reform shaped article
Shaping against forming surface
264316, 425389, B29C 5128
Patent
active
054965110
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a new industrial product consisting of a system for providing rolled edges on lampshades, these edges being rolled around the upper and lower hoops of the said lampshades. The hoops in question are made mainly of iron wire, while the blanks consist of a thermoplastic material which may or may not be coated and may or may not be bonded, especially to fabrics.
Systems based on the principle of heating the edges of the lampshades followed by mechanical spinning analogous to metal spinning, especially of tins, are already known, the essential components of which are rollers and chases, the whole assembly operating in a circular movement. These systems have the disadvantage that it is difficult or impossible to use them on an industrial scale, while the edges in question undergo lamination detrimental to their aesthetic appearance and flatness.
This invention aims to obviate these disadvantages and relates to a system for forming the edges of the lampshades by a static process.
Once the blank of the lampshade has been assembled, essentially forming a truncated cone, it is placed on a form provided in advance with the upper and lower hoops of the lampshade.
The upper and lower ends of the blank are then heated to their softening point, then an elastic membrane is sucked on to the said blank, shaping the latter on its support.
The lampshade is finished.
The invention will be more readily understood with reference to the following text and the accompanying drawings, in which:
FIG. 1 is a section of the lampshade;
FIG. 2 is a section of the form;
FIG. 3 is a section of the form with the upper and lower hoops;
FIG. 4 is a section of the form with the upper and lower hoops and the blank;
FIG. 5 is a section of the system during heating;
FIG. 6 is a section of the system after heating and during application of the membrane;
FIG. 7 is a section of the system after lowering of the membrane;
FIG. 8 is a section of the system during sucking of the membrane;
FIG. 9 is a section of a variant of the system, the upper hoop being provided with a support, and
FIG. 10 is a top view of FIG. 9 without the upper hoop and without the support in place.
A lampshade produced according to this system consists of upper (1) and lower (2) metal hoops and a blank of thermoplastic material (3).
The hoops are held on the blank by virtue of a crimp formed by appropriate deformation of the edges of the said blank (4) and (5).
The said crimp is produced on a form or mandrel (6) which comprises all of the elements required to this end, i.e.: a shape perfectly matching that of the lampshade, an adequate slope (7), a recess (8) adapted to receive the upper hoop and a recess (9) for the lower hoop, a shoulder (10) and a recess (11). Finally the form is placed on a table (13).
The following are placed on the form in sequence as the edges are rolled according to this system: the lower hoop (14), the upper hoop (15) and the assembled blank (3).
Once these three elements have been mounted, two heating plates are introduced, an upper plate (16) adapted to heat the upper edge and a lower plate (17) adapted to heat the lower edge.
These plates remain in position for the time required to heat the said edges.
Once the said edges have been softened by the action of the temperature the said plates are removed.
An elastic membrane (18) placed in a frame like a drum is then placed over the top of the form. This membrane is then applied to the form by a vertical movement until the frame (26) touches the table (13).
The upper edge (19) of the blank then begins to deform under the action of the said membrane.
At that moment, a vacuum is created in the said form, so that the membrane is fitted on to the form, taking with it the upper and lower edges of the blank so as to bend them (20), (21) around the hoops. Once crimping has been effected the suction is stopped and the membrane resumes its original flat shape.
The membrane is then removed and the finished lampshade can be removed from its housing, i.e. the form.
As a variant, the upper ho
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Corep
Timm Catherine
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