DE20311637U1 - Device for deforming plate-like material - Google Patents

Abstract

The mold to give a three-dimensional shape to thermoplastic boards, and especially of a mineral plastics, has a concave half-mold (1) to hold the plastics board (K) and is covered by a clamped gas-impermeable membrane (2) with stretch elasticity. The mold to give a three-dimensional shape to thermoplastic boards, and especially of a mineral plastics, has a concave half-mold (1) to hold the plastics board (K) and is covered by a clamped gas-impermeable membrane (2) with stretch elasticity. The membrane is sealed by a plate (3) against the upper edge (4) of the half-mold, pressed home by the plates (8,8') of a hydraulic press. The gap between the sealing plate and the membrane is filled (5) with compressed air, to press the heated plastics board into the lower half-mold against the concave inner contour. The lower half-mold can be evacuated by a vacuum pump.

Description

The invention relates to a device for deforming plate-shaped material made of thermoplastic material, in particular mineral plastic.

Plastic sheet material has so far been pressed into a molded body by exposing it to the pressure of a hydraulic press between two metal or wooden tools. This process is expensive because the tools have to be very sturdy and have extremely precise surfaces. Aluminum molds with polished surfaces are predominantly used. Due to the high costs, this press forming process is only suitable for the production of large series, such as wash basins.

The cheaper alternative to this press forming is vacuum forming. Here, the sheet material is exposed to a vacuum and thus pressed into one half of the mold. The advantages of this are the ease of use, the lower tool costs and thus the possibility of producing smaller series or individual pieces more cost-effectively. The disadvantage, however, is that vacuum forming is limited to a relatively low pressure on the sheet material, namely only atmospheric pressure, which impairs its applicability for strong deformations or deformations that require relatively high forces.

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- 2 - KEEL&SCHAAFHAUSEN

PATENT ATTORNEYS

In both processes, the sheet-shaped plastic material is brought to an elevated temperature before deformation, for example using special heating machines.

In recent times, so-called mineral plastics (such as those on the market under the brands "Cohan" by DuPont or "Quaryl" by Villeroy & Boch) have become very popular for use in sanitary items such as bathtubs or shower trays, but also in the kitchen area for sinks, washbasins and the like. These mineral plastics and comparable other plastics are characterized by relatively high toughness, so that cost-effective vacuum forming is practically not an option.

The object of the present invention is to propose a device for deforming plate-shaped material made of thermoplastic plastic, which can be used in a simple and cost-effective manner also for plastic materials, such as mineral plastics, which offer a relatively high resistance to deformation.

According to the invention, a device is proposed for shaping plate-shaped material made of thermoplastic plastic, in particular mineral plastic, into three-dimensional molded bodies, such as bathtubs, sinks, wash basins, vanity units, cladding, panels, furniture parts, work surfaces, window sills and the like, which has a concave mold half for receiving a plastic plate, a gas-impermeable, elastically stretchable membrane made of e.g. heat-resistant silicone rubber that can be stretched over the mold half, means for sealing the membrane against the upper edge of the mold half and means for applying a compressed gas, in particular compressed air, to the space between the membrane and the sealing means.

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- 3 - KEIL&SCHAAFHAUSEN

patent attorneys

With this device, a process for deforming sheet-like material made of thermoplastic material can be carried out with the following process steps:

- Inserting the heated plastic sheet to be formed into a concave mould half, e.g. that of a pressing tool or a vacuum press,

Sealing the upper edge of the mould half by covering it with a membrane made of impermeable elastically stretchable material, such as high-heat-resistant silicone rubber,

Pressing the membrane onto the edge of the mould by means of a rigid cover, e.g. plate or lid-shaped cover, and
15

Pressurizing the space between the membrane and the cover with a compressed gas, especially compressed air.

With such a device, the same deformations as with the complex press forming can be achieved at low tool costs (since only one mold half is required), i.e. even complicated three-dimensional shapes and also when using mineral plastics and similarly resistant plastics. Due to the pressure applied to the highly heat-resistant membrane made of silicone rubber or similar elastic material, the plate-shaped material is pressed into one half of the mold in order to take on its inner contour. A further advantage of the device according to the invention is that it can be carried out with both the one half of a hydraulic press and the concave half of a traditional vacuum press. Companies that already have such presses at their disposal therefore do not need to make a large investment.

July 28, 2003

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KEOL& SCHAAFHAUSEN

PATENT ATTORNEYS

wall for the conversion of an existing plant. Only the process management has to be changed.

Because of the good sealing of the concave mold half at its upper edge, the forming process can be further improved by subjecting the underside of the sheet material to be formed to a negative pressure using a vacuum pump while the upper side is being pressurized, as is already the case with a vacuum press. For this purpose, the device can also be equipped with other means for generating a negative pressure on the side of the plastic sheet opposite the side that can be pressurized with compressed gas.

Particularly good economic efficiency is achieved when the plastic sheet to be formed is heated to between about 150 and 180° C before being placed in the mold half - depending on the plastic. This is achieved when the device is assigned means for heating the plastic sheet. The mold half, on the other hand, should be cooled so that the material cools down quickly and a high throughput can be achieved.

The concave mold half can be part of a pressing tool or a vacuum press. The means for sealing the membrane preferably comprise a rigid cover, e.g. in the form of a plate or lid.

Further aims, features, advantages and possible applications of the present invention will become apparent from the following description of embodiments with reference to the drawing. All described and/or illustrated features form the subject matter of the present invention, either individually or in any combination, regardless of their summary in individual claims or their reference back to one another.

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- 5 - KEIL& SCHAAFHAUSEN

PATENT ATTORNEYS

Show it:

Fig. 1 shows schematically in vertical section a device implementing the invention

Deformation device and
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Fig. 2 shows another embodiment of a device according to the invention

Deformation device, also in vertical section.

The device shown in Fig. 1 has a mold half 1 with a corresponding concave inner contour, which is to be taken up by a plastic plate 6 during deformation, here for example the indicated shape of a bathtub. This can be the lower mold half of a hydraulic press or the mold half of a vacuum press.

The plastic sheet K to be formed is placed from above into the cooled mold half 1 after it has been heated to, for example, around 150 to 180° C. A gas-impermeable, elastically stretchable membrane 2, for example made of highly heat-resistant silicone rubber, is stretched over the upper edge 4 of the mold half 1, which preferably projects slightly beyond the plastic sheet K. A plate 3 is placed on the membrane 2, which can be pressed against the membrane 2 of a hydraulic press between a lower table plate 8 and an upper table plate 8 ¹ to reliably seal the edge. The plate 3 has a compressed air connection as a pressurizing means 5, via which compressed gas, e.g. compressed air, can be introduced into the space between the plate 3 and the membrane 2. The membrane 2 therefore lies against the upper side of the heated plastic sheet K and presses it into the concave inner contour of the mold half 1 until it is completely flush with the inner contour. After cooling the molded body thus created, which can be accelerated by cooling the mold half 1, for example, the thus created

July 28, 2003

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- 6 - KETL& SCHAAFHAUSEN

PATENT ATTORNEYS

The molded body can be removed and the device can be used for a new process step.

The forming device shown in Fig. 2 works in principle like the one shown in Fig. 1. It differs essentially only in that here the mold half 1 is equipped with a vacuum press with vacuum holes as a negative pressure generating means 7 within the concave recess of the mold half 1. In addition, a special clamping frame 9 for the elastic membrane 2 is illustrated here. The sealing at the upper edge 4 of the membrane half 1 with the membrane 2 in between is carried out here with a special cover 3, for which a locking mechanism 10 is indicated (on the left side of the drawing), a second of which (not shown) is located on the right side of the mold half 1 in order to press the cover 3 evenly onto the edge 4 of the mold half 1. The cover 3 is also provided with a compressed air connection as a pressurization means 5.

July 28, 2003

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Khl&Schaafhausen PATENT ATTORNEYS

List of reference symbols

1 2 3 4 5 6 7 8 9 10

Mold half

membrane

Sealant, plate, lid

Edge of the mold half

Pressurizing agent, compressed air connection

Space

Vacuum generating means, vacuum drilling

Table top

Tension frame

Locking

Plastic plate

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Claims (5)

1. Device for shaping sheet-like material made of thermoplastic plastic, in particular mineral plastic, into three-dimensional shaped bodies, such as bathtubs, sinks, wash basins, vanity units, cladding, panels, furniture parts, work surfaces, window sills and the like, with a concave mold half ( 1 ) for receiving a plastic sheet (K), a gas-impermeable, elastically stretchable membrane ( 2 ), such as heat-resistant silicone rubber, which can be stretched over the mold half ( 1 ), means ( 3 ) for sealing the membrane ( 2 ) against the upper edge ( 4 ) of the mold half ( 1 ) and means ( 6 ) for pressurizing the space ( 7 ) between the membrane ( 2 ) and the sealing means ( 3 ) with a compressed gas, in particular compressed air. 2. Device according to claim 1, with means ( 7 ) for generating a negative pressure on the side of the plastic plate (K) opposite the side which can be subjected to compressed gas. 3. Device according to claim 1 or 2, with means ( 7 ) for heating the plastic plate (K) to between about 150° and 180°C. 4. Device according to one of the preceding claims, characterized in that the concave mold half ( 1 ) is part of a pressing tool or a vacuum press. 5. Device according to one of the preceding claims, characterized in that the means ( 3 ) for sealing the membrane ( 2 ) have a rigid cover, e.g. in the form of a plate or lid.