DE1250627B - Method and device for producing a hollow body from thermoplastic plastic films - Google Patents

Description

Method and device for producing a hollow body from thermoplastic Plastic films The invention relates primarily to a method for Production of a hollow body from thermoplastic plastic films, which are plasticized in the State can be brought into die-like shapes.

It is already a method of producing several at the same time Hollow bodies made of thermoplastic plastic films known; in this procedure the still fairly soft films coming from the extruder essentially occur freely between the individual molded parts; the foils therefore stretch under the influence of their own weight, while the irregularity that is already present in the Strength of the extruded films is increased.

The invention is based on the object of a method of the above-mentioned Kind of creating in which the thermoplastic films are not just molded, but also welded and the disadvantages of the known method can be avoided.

The object is achieved in that for the production of a double-walled Hollow body two foils heated to welding temperature between the molded parts in the Maintained distance from one another, each deformed on these molded parts and then at substantially the same temperature at certain points on the film area are welded together.

A modification of the method according to the invention is that the deformation of the foils in a manner known per se by deep drawing with the aid a suction effect takes place; also can at least one during the deformation of the foils at the later welding points bumps or the like. Are produced.

According to a further modification of the method according to the invention can preferably intersect at least one of the foils during the deformation bead-shaped depressions are produced.

The invention is also based on the object of implementing one to create particularly suitable device of the method according to the invention.

This device is cooperating with a die-like and a Provided clamping frame having shapes and characterized in that the clamping frame has separate frame parts for each slide and the shapes are separated from Tension frames cooperate with each other.

This device can also be modified in that the Forms with per se known th channels for connection to a vacuum source are.

The following is an embodiment of the invention Device and several possible uses of the method according to the invention explained with reference to the drawings; It shows Fig. 1 a sectional view through a Frame for the storage of to be produced by the method according to the invention Foil is used, F i g. Figure 2 is a sectional view through a press inside which the of the in F i g. 1 frame supported foils can be edited can, F i g. 3 shows a partial view of a component produced according to the invention in FIG diagrammatic representation, FIG. 4 a sectional view along the line 44 in FIG. 1, Fig. 5, on an enlarged scale, is a partial sectional view showing a film represents clamped between two die parts, F i g. 6 is a partial view in diagrammatic form Representation of part of a filling wall produced according to the invention, FIG. 7 a Sectional view along the line 7-7 in Fig. 6, F i g. 8 is a diagrammatic representation of a part manufactured according to the invention, F i g. 9 is a sectional view along the line 9-9 in Fig. 8, F i g. 10 is a partial sectional view through a Part of a film support frame and the interacting die parts, FIG. 11 a partial sectional view showing the connection of related trough-shaped Represents components for the manufacture of a part according to FIG.

The inventive method can be used to produce many different Moldings are used.

It is also possible to use various plastic compounds that are suitable for the production of the components described below. Polyethylene foils have proven to be suitable. Such films are available in various densities and Z. fl. as indicated below on the market: Type 1 * 0.910 to 0.925 g / ccm Type II 0.926 to 0.940 g / ccm Type III 0.941 to 0.965 g / ccm ASTM designation: D 1248-58T.

The polyethylene can be in the form of a homopolymer or a copolymer to have.

Other suitable thermoplastic compositions are: Rigid or Partial plasticized vinyl homopolymers; Polystyrene homopolymers or polystyrene copolymers with acrylonitrile or methacrylic acid methyl ester; Terpolymers or physical Mixtures of acrylonitrile, butadiene and styrene polymers from the commercially available as ABS polymer designated type; rigid or plasticized cellulose derivatives, such as cellulose acetate, cellulose acetate butyrate, cellulose propionate or ethyl cellulose; Acrylic or modified acrylic compounds.

For the implementation of the method according to the invention, two Plastic or plastic foils kept at a distance from one another for heating. It has been found to be a preferred way of holding the two plastic sheets for heating, swaging and fusing consists in keeping the foils inside a frame 20 are held.

In Fig. list is a simple embodiment of such a framework shown, which consists of three frame sections, i. H. from a middle section 21, an upper section 22 and a lower section 24. The one shown Frame has a shape that is used to produce a substantially rectangular bulkhead which is shown in FIG. However, the frame can also have any other shape as far as it corresponds to the shape of the body to be produced. The top and the lower section 22 or 24 can be independently of one another on the middle section 21, hinged as shown by hinges 26 or otherwise on the central section be attached. The edge of the frame opposite the hinge can with its Sections 22 and 24 firmly held together with the middle section 21 by tension springs 28 which end at pins 30 so that the frame sections are held together that the space within the frame between the foils is preferably substantially is hermetically sealed.

The upper plastic film is designated with 32 and the lower with 33. The two foils are clamped within the frame so that they are through this are held at a substantially parallel distance from one another. In the F i g. 1 slides drawn with full lines have a slight Sag shown, as they already have something on the effect of the above and below of the frame arranged heating elements 34 have addressed. The heating elements can be of any type and are used to apply the foils to the welding or To heat melting temperature. The heating elements are in the present case as two spaced parallel rows of heating lamps have been selected.

The frame sections 21, 22 and 24 can, as in FIG. 4 shown be trained in this way. that they have ribs or ratchet-like parts 36 that engage in corresponding recesses 38 to the foils within the frame firmly gripped and held against unintentional displacement.

The frame described above can be any mechanical Have training. The frame shown has a shape through which two essentially foils of the same size are kept at a distance from one another. Such a framework can be designed so that it holds the foils between two die parts.

The respective opening of the frame and the distance between the foils can be set as desired. The frame is arranged so that the foils stored in this can be heated to the welding or melting temperature.

While the foils are stored in the heated state inside the frame are, the die parts are moved so that certain heated areas of the foils be squeezed between them.

The frame shown is with an air outlet or air inlet pipe 40 provided, which communicates with the space between the foils within the frame and through which air can be extracted or introduced. To this pipe 40 is connected to an air valve control device (not shown). The inventive The method is applicable to both vacuum forming and blow molding.

In Fig. 2 is a schematic representation of a die assembly which has a base plate 42 which has stationary guide columns 44.

A lower die part 46 and an upper die part 48 are provided. The lower die part 46 is arranged on the base plate. The upper die part is supported by an upper die support block 50 which is supported by an up and down movable punch 52 carried and supported by the guide columns 44 slidably is.

The lower die part is connected to a vacuum or pressure line 54 provided, which is connected to a series of branch lines 56, the lead to the specific areas of the die surface.

The upper die part 48 is connected to a pressure or vacuum line 58 equipped, which is provided with a series of branch lines 60 leading to the specific areas of the die part 48 lead. Valve control organs are located in these lines (not shown) provided.

The base plate 42 of the die assembly is provided with supports 62, on which the in F i g. 1 shown Frame 20 rests. The frame itself is located outside of the die surfaces as shown. The edge cohesion or -welding parts of the upper and lower dies, indicated 64 and 65. serve to capture the two foils and hold them firmly on the edge, e.g. B. for welding, to keep on that line. The processed area of the foils lies within this Edge line. Such an edge weld is shown in Fig. 3 at 66, the protruding edge part 88 outside the weld line 66 can be separated.

To facilitate the interaction of the upper and lower Die portion along these marginal retaining edges 64 and 65 and at other desired ones One die part, for example die part 48, can provide a shoulder section 70 from a deformable thermosetting polyester or epoxy resin or from a other suitable similar material. This shoulder section 70 can be adhered to die part 48, with the molding for adjustment to the opposite area of the associated cooperating die thereby can happen that the shoulder portion against the shoulder portion of the other Die part is pressed, which eliminates the need to remove the die parts 46 and 48 precisely by painstaking manual labor for the cooperating fitting intervention to shape.

The die to which the flexible plastic shoulder is attached, is designed so that it approximates the cooperating part of the other Lowered matches whereupon the thermosetting shoulder is formed under the pressure of the die will.

The use of the thermosetting shoulder contact part on a die part serves another important purpose as well. It is insulating and does not conduct heat Effect insofar as it absorbs the heat from the film by the thermosetting Shoulder contact of the die through delayed. It therefore contributes to the slide at one point of the intended "merger" for a longer period of time maintain the melting temperature than it would if the contact point would be made of metal. If the mentioned contact point were made of metal, the heat absorption could take place so quickly that the one available Not time to complete a complete weld of the two foils in the desired places is sufficient.

F i g. 2 shows the device according to the invention for production a substantially rectangular filling wall of the in F i g. 6 shown type. The in F i g. The filling wall shown in FIG. 6 is made from two foils 32 and 33. A Cross-section through the latter is shown in FIG. 7 shown. The top sheet 32 can on the upper die surface to form a number of squares 72 forms, which give a cushion-like raised appearance. The squares 72 are separated from one another by recessed lines 74. The two slides are on at a distance points 76 (FIG. 6) located from one another are welded to one another, which approximately correspond to the fastening buttons used in upholstery. The component is formed so that a hollow rim portion 78 in the form of a flattened tube arises, which extends around the filling wall.

The two foils are between the shoulder parts 64 and 65 of the Die parts and along the edge line 66 welded together. The inside edge this tubular edge portion 78 is attached so that the films only on the im Points 76 located at a distance from one another are welded.

For a filling wall, the upper film 32 can be made from a plastic compound exist, for example, to achieve a pleasing cushion-like appearance may be a polyethylene homopolymer or polyethylene copolymer. The lower one Foil 33 can consist of a plastic compound that has a fairly dense, stiff, however, elastic film results, for example with a polyethylene homopolymer a density of 0.941 to 0.946. Like F i g. 7 shows, the top sheet is raised worked out, while the lower film is deep-drawn, so that it has deepened support or bearing surfaces 80, which can be circular and are located under the Square areas 72 of the upper film are located, but are separated from these. These deeply embossed areas or surfaces 80 are relatively stiff, but elastic and reinforce or support the square surfaces 72. The latter give, since they consist of one Material are formed that is much more flexible than the material from which the lower layer is formed, the outer surface of the filling wall a soft cushion-like "Feel". The deeply embossed areas 80 result in a substantially resistant, however, elastic support against the squares 72 being pressed in further.

The two foils can of course consist of a different plastic, which is deemed most suitable for the intended purpose. The described Masses have proven to be satisfactory for the purposes in question.

The procedure is as follows: There are two foils made of plastic, for example made of polyethylene, in a frame at a distance of one other and held essentially parallel to each other. The one carrying the foils The frame is placed between the two die parts. When the die parts are relative be moved towards each other in order to bring them closer to the foils, between each Foil and the die part adjacent to it along the boundary line 66 (F i g. 3) thermal contact is established. Between each foil and the face of the die part a vacuum can also be created. which pulls the foil towards the die surface. During this vacuum formation, the line 40 is in communication with the outside air. The movement of the two die parts' continues until they hit the opposite one Sides of the two foils are in contact. As can be seen from FIG. 2 results the two foils between the die parts and on the boundary line, which is formed by the shoulder 64 and 65, welded together. this leads to for welding along line 66, as in FIG. 3 shown. The two slides are also at locally spaced points 76 between the squares 72 fused together.

As can be seen from Figure 3, at the welds 76 are longitudinal the boundary line 66 the two foils at the points of contact to form a homogeneous one Mass merged. They are not only adhered to one another as independent foils, but also with the formation of a single homogeneous layer along the melt line connected with each other. The line 40 is surrounded by the die parts, so that the foils are welded around the boundary with the exception of that point and compressed on which the conduit or tube 40 is disposed.

The foils are also connected to one another by protruding die members 75 fused, which on the cooperating surfaces of the die parts 46 and 48 facing each other. The foils are formed between these weld points 75 pressed together by homogeneous dimple-like fusion points, which are shown in Fig. 3 and 6 with 76 and in F i g. 9 are denoted by 108.

The procedure is that at the points where there is a merger should take place, the latter going on at the same time; those at a distance Parts are held so that they rest against the die surfaces.

Due to the fact that the films are preferably on a uniform Temperature to be heated over its full extent and heating and molding under the same temperature conditions and the cooling takes place at the same time is done over the entire film, the entire production can be done in that way be carried out so that no local stresses occur that lead to a delay or a twist or the like. Could lead.

Instead of a vacuum, the foils are pressed against the forming die surfaces to pull, a medium pressure can be generated between the foils, which the foils presses against the die surfaces. In these cases, lines 54 and 58 serve as air exhausts.

In Fig. 8, 9 and 11 is a possible application speed for the invention A method, namely a square tube, indicated generally at 98, is shown is. This tube can, for. B. a hot air duct for the heating system of a motor vehicle be.

The tube 98 consists of two substantially uniform hollow ones Halves or U-shaped parts 102. These two parts are joined together welded in the manner described below.

Each part can be used as described above for the manufacture of the filling wall described method are produced.

As can be seen, each part has an outer film or wall 102 and an inner sheet or wall 104. These two walls are at a distance from each other shown so that they form a hollow-walled or jacketed tube. The edges the two side walls of the separately manufactured parts are bridged or depressions 108 held at a distance from one another. These wells can to be provided in such a number as is necessary for safe spacing appears necessary between the two walls. As shown in FIG. 11 can be seen, extends the fused edge of the lower part, which is shown in the drawing with 106a, beyond the edge of the upper part or includes the latter.

After the two parts have been formed in the manner described are attached to each other. To this end, the end 110 of the edge part becomes 106a bent and welded on this, so that a secure connection along the Edge is obtained.

In Fig. 10, a die apparatus is shown in which the upper die part 48 has a deep-drawing means area 49. This area 49 takes effect, as shown, on the upper film 32 and presses it towards the opposite film; before the two foils are fused, the shoulder 64 represents of the die part 46 makes sealing contact with the film 32 so that an im The vacuum generated by the die part via the lines 60 pulls the film 32 against the latter.

From the explanations it follows that the method according to the invention is applicable to the manufacture of various parts or components. It surrenders also that these parts have the presence of different physical properties may require, so that the plastic masses can differ from one another. the Foil is thermoformable, but its physical properties can vary be.

Claims (6)

Claims: 1. A method for producing a hollow body from thermoplastic plastic films, which in the plasticized state in die-like Brought trained forms, there at least partially welded together and are formed within the weld edges by a pressure differential, thereby characterized in that for the production of a double-walled hollow body two at welding temperature heated foils between the molded parts held at a distance from one another on the molded parts each deformed individually and then at a certain temperature essentially at the same temperature Places of the film area are welded together. 2. The method according to claim 1, characterized in that the deformation the foils in a manner known per se by deep drawing with the aid of a suction effect he follows. 3. The method according to claim 1 or 2, characterized in that during the deformation on at least one of the foils at the later welding points Bump or the like. Be made. 4. The method according to any one of claims 1 to 3, characterized in that that during the deformation at least one of the foils preferably intersecting bead-shaped depressions are produced. 5. Device for performing the method according to one of the preceding Claims with forms which cooperate in a die-like manner and which have a clamping frame, characterized in that the tensioning frame has separate frame parts for each film (32, 33) (21, 22, 24) and the molds (46, 48) separated from the clamping frame with one another cooperate. 6. Apparatus according to claim 5, characterized in that the forms (46, 48) with per se known channels (54, 56, 60) for connection to a vacuum source are provided. Documents considered: German Auslegeschrift No. 1,080,294; French patents nos. 961 760, 988 510, 1021858.