DE2053070A1 - Making thermoplastics panels - by contact heating with suction plates - Google Patents

Abstract

A method and appts. for making thermoplastics panels acts by use of contact heating pltes. One of the contact heating plates, pref. the upper one, is used for transporting the panel. Typically the upper, cold pre-shaped panel is removed from a stack of cold panels by suction lifting, using the upper contact plate, is transferred onto the heating bed into contact with the lower contact plate and heated there. After heating it is again lifted by the upper contact plate to the pressing station.

Description

Description of the patent application dated 1d, 10, 1970, method and device for thermoplastic shaping of plastic sheets during thermoplastic Semi-finished product in the shape of a pelvis processed in thermoforming machines with a stationary heat source the thermoforming machines for processing plastic sheets are mobile Radiator on. Dor-like molding machines with preferably infrared heaters are allowed be assumed to be known. In particular, those used in the Kiefel molding machines Carz emitters have radiation that is adapted to the absorption of thermoplastics Heat, the good penetration of the radiation into the plates and thus better heating enable.

Infrared emitters generally have the advantage that they are easy to use customize the different formats.

But since the radiation decreases with the square of the distance and ray it must always have a greater or lesser distance to the plastic plate, are lateral radiation losses and partial penetration of the radiation, such as also losses due to i? eflexion cannot be avoided.

The efficiency of such radiators is therefore not particularly good.

There are also other sources of heat, such as irontal heating and convection heating known. With the contact heating currently in use, however, only rolls can be processed and the molding machine is tied to the format of the heating plate.

The convection heating is tied to the capacity of the heating stove, therefore works in batches and comes because of the cumbersome plate transport not suitable for industrial series production.

The present invention relates to a thermoforming system with associated Device for plastic plates equipped with a new contact heating system The device (according to drawing 1) consists, for example, of a lifting table 1 for Aufnaiirie the plastic plates 2, provided with a lifting mechanism 3, the always brings the top plate to the same level. A contact heating plate 4, provided with a lifting mechanism 5, which is designed to be horizontally movable, brings the top plastic plate onto a stationary isontakt heating plate 6. Both Contact heating plates are provided with suction devices around a) the upper heating plate to be able to transport the plastic sheet and b) full surface during the heating season Ensure fit of the plastic plate on the heating plates.

Applying the cold plastic plate to the stationary lower one iContact heating plate can also be done by a gripper or suction arm, which is independent, or is moved together with the upper heating plate. (the additional loading device is not shown in the drawing).

After the plastic plate 2 has been heated to the desired level Mold temperature, this is released from the lower heating plate 6 by a blast of air and at the same time, or shortly thereafter, lifted from the upper heating plate 4 and in the forming station transported. The upper meat plate 4 is lifted with the lifting mechanism 5 lowered onto a clamping frame 7, of which the heated plastic plate on the circumference sucked in and held. The upper heating plate 4 is again through a Air blast released from the plastic plate, lifted and in the starting position moved back, from where the next plastic plate is already in the heating station inserts.

The tensioning frame (drawing 2) according to the present patent application represents a further development of the clamping frame according to bsterr.

Pat. No. 1,850,995 of May 3, 1962 and No. 1,850,994 of May 3, 1962 and patent application 1t. File number P 2011 178.8.

The illustrated clamping frame is based on the following mode of operation. The heated plastic plate is pushed from the heating plate onto the rubber seal 2 of the subframe and placed by side suction, not shown, up to lilemilung held on to the subframe. The upper frame can optionally be used as a rigid one or adjustable upper stimuli, which can be controlled by a lifting mechanism from placed on top, or folded out, or as hinged strips on the lower frame.

The two drawings represent a frame attached from above represent.

Functioning of the clamping space according to Pat. Note P 2011l78.8 from G. 3. Executed in 1970 as a vacuum clamping frame.

I) ie through the upper heating plate (drawing 1, no. 4) onto the rubber seal 2 placed, heated plastic plate (drawing 2, no. 9) is removed by suction of the Air held in rubber profile no. 2 and clamped by placing the terminal strip 3.

This is connected to the vertically movable upper frame 5, the carries a suction lip 6 on the underside. With this suction lip G, the upper frame sucked to the lower angle frame 4, whereby the for holding the plastic plate 9 required clamping force is generated. The lower clamping strip l with the sealing profile 2 is arranged displaceably at the angle 4 via inclined grooves in order to adapt to to allow the plate thickness. The clamping strip 8 attached to the upper frame holds that required for air supports and pneumatic pre-stretching of the plastic sheet Pre-blow sheet firmly and at the same time seals on the circumference of the clamping frame. In order to the pre-blowing chamber of the molding station with the one on the outer circumference of the blow box Attached pre-blown sheet closed airtight at the top.

The clamping frame described can be either rigid or adjustable Execution are made.

To retract the molding tool 8, the molding table 9 is equipped with a lifting mechanism, for example a scissors ile table equipped, the least Allows construction height with a large stroke.

For mechanical pre-stretching, the counter punch can be used with the same Be equipped lifting device. The counter punch is used to demould deep parts usually designed to be laterally extendable. The forming station can be used for both pure Vacuum forming as well as compressed air forming and mechanical pressing can be carried out. The vacuum pump LO and the vacuum vessel 11 are in the present illustration indicated under the heating station.

Advantages of the method described above and the associated device: The present invention offers the advantages that now also thick plastic sheets can be heated in an upstream heating station while at the same time The forming and cooling takes place in the following forming station.

The device described also offers the advantage that the plastic plates automatically into the heating station and automatically and precisely after heating be transported into the forming station. The device described also offers the possibility of automatically discharging the molded parts. The one in the drawing 1 can also be offered to various forming stations.

The execution of the liftable form table by means of a scissor lift table enables a large table stroke and thus a large molded part height with the lowest overall height.

Insertion of the heated plastic plate through a heating plate holds the plastic plate over the entire length until it is taken over by the clamping frame Surface at constant mold temperature. The adjustment of the heating plates to a constant Temperature makes the device largely independent of the heating time, so that the plates can remain in the heating station longer if necessary. the Limiting the temperature in the heating station eliminates the risk of fire during warming Flame-sensitive plastic sheets, due to the good contact and Heat transfer from the heating plates to the plastic plate and the better insulation option compared to other heating systems, the contact heating described above also works a fraction of the energy required.

The present embodiment of the device lends itself to the mechanical Removal of the shaped parts and precisely fitting insertion into a downstream Separation station or other post-treatment.

Claims (8)

PATENT CLAIMS Method and device as described above and attached Drawings, for forming thermoplastics in sheet form, thereby characterized in that 1. the heating of the plastic plates by contact heating 2. The method and apparatus according to claim 1, characterized in that one of the two contact pickling plates, preferably the upper one, for transporting the plastic plates is used. 3. The method and device according to claims l and 2, characterized characterized in that the insertion of the cold plastic plates optionally by a separate device or from liand. 4. The method and device according to claims 1- 3, characterized in that that the heated plastic plate of the movable contact heating plate fits perfectly is placed on the stenter and heated until it is handed over. 5. The method and device according to claims 1-4, characterized in that that during the molding and cooling process in the molding station, a new plastic plate from the mobile contact heating plate or a separate insertion device in the heating station is inserted and warmed up. 6. The method and device according to claims 1-, characterized in that that the heated plastic plate from the clamping frame by vacuum suction of the contact heating plate and held until it is clamped by the upper frame will. 7. The method and device according to claims 1 - 6, characterized in that that the plastic plates prepared for insertion in the Ileizstation can be removed by the mobile contact heating plate from a lifting mechanism be brought to the same height. 8. Device according to claims 1-7, characterized in that that the molding table is moved vertically by a scissors-Ile table.