DE2328368B2 - THERMO FORMING DEVICE FOR THE PRODUCTION OF MOLDINGS OF LARGE DEPTH FROM A RELATIVELY THICK PLASTIC STRIP - Google Patents

Description

The invention relates to a thermoforming device for the production of moldings, in particular thin-walled moldings of great depth from a relatively thick plastic tape, in which the plasticized plastic tape is gradually passed through a forming station is passed, in which a possibly designed as a multiple tool molding tool on an unc the corresponding counter-molded part on the other side de: part of the plastic strip to be deformed vertically can be moved against this, the mold and the counter-mold each having a separating element Cut out the part of the plastic tape that has been taken over and shaped by the molding tool are and the molding tool in a position away from the plastic construction for the delivery of the moldings except half of the forming station is movable from this.

In known Thermofonr.vorrichtungen this Ar, the cutting device for cutting out de; taken over by the mold and shaped part of the plastic tape in that on the front side egg Edge of the molding tool a knife ring firmly connected to the molding tool is attached, true the counter-molded part, in particular a stretching aid, carries a ring-shaped counter-knife, which is also firmly attached is connected to the stretch helper (DT-AS 11 66 455). Be Such a separating device is an effective shearing of the taken over from the mold molded part of the plastic tape from the remaining tape only possible if either that is to be cut

so the material, i.e. the plastic tape, has cooled down considerably is solidified or if both knives fit each other very closely and no noticeable cutting edge Form a gap in which thermoplastic material that is still warm could be drawn in. This latter condition but - as experience shows - can not be met with the known device, because all of them due to the different temperature conditions prevailing on the molding tool and the stretching aid nisse a fairly large cutting gap between de

bo knives running one above the other must be left When processing relatively thick plastic tape that is still very warm or hot in its core in any case plastic fringes! in such a The cutting gap is drawn in, making it an effective one

h5 separation of the material remaining in the mold vo made impossible for the rest of the tape. For the safe operation of thermoforming machines where there Molding tool the molded part of the plastic bar

, fnimnit and take her to detaching from the rest ^ H us the forming station, it is te law meaning that a complete clean ^essence is made nen because otherwise the danger that lit ^{the best} at moving out of the Formwerkzeu 'Vol. ₁ Forming station the S ^{eS a taken up by it} , _{it would} hold plastic tape on the remaining tape A pulled out of the molding tool or at least ■ the molding tool would be loosened. Both would seriously disrupt the flow of the thermoforming passage. In contrast, the invention has the task of equipping a thermoforming device for the production of moldings, in particular thin-walled molds of great depth from a relatively thick plastic frame, with such a separating device that acts in the molding station and that is independent of the temperature-dependent conditions and separating difficulties at the edge of the molding tool. This object is achieved according to the invention in that the separating elements are attached to separate, separate from the mold and counter-molding, each circumferential distance from these arranged separating element carriers, which always remain in the forming station on both sides of the plastic strip can be moved vertically against this.

The invention achieves that when Separating out parts of the plastic tape, which is still hot at least in its core effective, clean and safer cut is performed that completely removes the from The tool is still warm and deformable Band area without any risk that is made possible by connecting bridges that are still in place Damage or malfunctions could occur.

In a particularly advantageous embodiment of the invention is on the mold side of the Separating element carrier arranged on the plastic band as a plate parallel to the band path with a central circular section formed, in which the molding tool with its opening edge with. Game can be introduced, the Peripheral edge of the circular segment a separating edge

In this case, a mold carrier that can be rotated about a horizontal axis and has two or more molds or sets of molding tools can be provided in which in certain rotational positions each a molding tool with its opening edge or the molding tools of a set the circular segment or face the circular sections of the vertically arranged plate.

The one in the circular section of the plate is useful the gripping opening edge of the molding tool is about the same height as the thickness of the plate around the circular section, while the molding tool by pushing the separating element carrier arranged opposite it its opening edge can be pushed into the mold carrier against the action of a restoring element and holding means are provided for holding back the mold in the mold carrier.

In this embodiment, the one arranged on the molding tool side of the plastic tape can also be used Plate of the separating device through the mold or its carrier against the action of a restoring element against a frame carrying the separating element carrier opposite the tool be movable.

Within the scope of the invention, pin clamping frames for the plastic strip can be assigned to the separating device be that during the introduction of the area of the plastic strip to be deformed into the molding tool and firmly clamps the area of the plastic strip to be deformed all around during the cutting process. In the preferred embodiment of the invention, this can be done on the mold side of the Plastic tape arranged plate of the separating device on its side facing the plastic tape at the same time be designed as a clamping frame part, whose ίο associated second clamping frame part one on the is arranged on the other side of the plastic band plate, which by means of the first clamping frame part !; against the Is displaceable by force of a spring. The second clamping frame part can have a central section of a circle have, through which the separating element carrier arranged opposite the mold with its Face on the opening edge of the molding tool and with its cutting edge in the sector of the circle The plate arranged on the molding tool side of the plastic belt runs.

An embodiment of the invention is explained in more detail below with reference to the drawing. It shows

F i g. 1 shows a device for producing moldings from plastic with a thermoforming device schematically in side view and

2 shows a partial section along the line 11-11 somewhat schematic.

The in F i g. 1 is formed by two units, namely a tape production unit 1 and a tape processing unit 2. The tape production unit contains an extruder press 11 with a slot die 13 from which a plastic tape 14 exits substantially at extrusion temperature. The material band produced in 3 ^r > the band production unit can be of relatively great thickness, for example have a thickness of 3 mm or more. However, this does not rule out that thinner plastic strips, for example 0.5 to 2 mm thick, can also be produced and processed with the device shown.

The tape processing unit 2 has a stabilizing device 22 which is continuously produced Plastic tape 14 takes up continuously shortly after leaving the slot nozzle 13 and for the subsequent The processing cycle is stabilized by cooling and cooling thin surface areas of the strip 14 solidified, while the plastic in the inner area lying between these surfaces of the tape 14 is left substantially at extrusion temperature and in a plastic state. Of the Stabilizing device 22 is the plastic band by means of a dancer roller 25 and a cooled Gripping device 26 containing allocation device in 5> shown example vertically from top to bottom gradually introduced into the thermoforming device 30 arranged below the gripper device. This thermoforming device 30 is characterized in the example shown by an arrangement of w) molds and their counter-mold parts, in which the molding tool part to be loaded with the material band is horizontally opposite the material band is. Furthermore, a device 50 for burning out the moldings is in the thermoforming device included from the material tape.

As the drawing shows, the thermoforming device 30 has a rotatable about a horizontal axis Mold holder 31, which is shown in the

Example contains four molding tools 32, each in the direction of rotation of the molding tool carrier 31 Are arranged offset from one another by 90 °. Individual forming tools are shown in the drawing for the sake of simplicity 32 shown. Instead, it is preferred to use multiple forming tools to with produce a plurality of moldings for each work train of the thermoforming device. As shown in Fig. 2 can be seen, each of the four molds 32 is contrary to the action of as restoring elements ι ο serving springs 33 inward in its axial direction, (1st i.e. after the center of the axis 36 of the mold carrier .31 mounted in the mold carrier 31 so as to be displaceable. Inside the mold carrier 31 are Holding means (not shown) attached, which hold the mold 32 for a predetermined time, for example, until the molding is ejected, at least until the molding tool holder 31 has reached its end has reached the horizontal starting position, hold back when pushed in. This avoids that the briquettes after completion of a forming and punching process back into the remaining strips of the plastic tape 14 are repelled.

In the in F i g. In the rest position shown in FIG. 2, each of the negative molds 32 also protrudes its opening edge 34 protrudes from the respective side surface of the mold carrier 31. On both sides of the respective molding tool 32 or multiple molding tool, the molding tool holder 31 has on each At least one side face, and in the example shown, two opposite one another with respect to the molding tool 32 Centering bores 35 with which the mold carrier 31 moves on the Plastic tape 14 runs to centering rods 28 attached to the machine frame 27.

The mold carrier 31 is rotatably mounted in a guide frame 37 about its horizontal axis 36, which is parallel to the surface of the vertically guided plastic strip 14. In the example shown, this guide frame 37 is fastened to two guide rods 38 which are connected to a crank mechanism 39 in order to produce a horizontal back and forth movement of the mold carrier 31. These guide rods 38 are slidably mounted along their horizontal longitudinal axes running at right angles to the surface of the vertically guided plastic belt 14 in a guide piece 29 attached to the machine frame 27, which also carries the centering rods 28 arranged parallel to the longitudinal axes of the guide rods 38. The mating mold part 40 opposite the molding tools 32 and the separating device 50 are also attached to the guide piece 29. The counter-molding part 40 is common to all molding tools 32 and, in the example shown, contains a stretching aid 41 adapted to the molding tool 32 or a stretching aid arrangement adapted to the multiple molding tools. This stretching aid 41 or the stretching aid arrangement is pushed horizontally into the accompanying mold by means of a pressure cylinder 42. _W i

On the centering rods 28 there is also a clamping frame 43 formed from three plates for the plastic band 14 arranged. This clamping frame 43 contains a rear stop plate 44, a middle one Klemmrahmcnteil 45 in the form of a plate and one on ι.-. the molding tool side of the plastic tape 14 lying plate 46. The stop plate 44 is attached to the guide piece 29, while the middle enrcil

Clamping framefdil 45 and the plate 46 along the Centering rods 28 are displaceable. The three plates 44, 45 and 46 are through between the stop plate 44 and the middle clamping frame part 45 arranged on the centering rods 28 as restoring elements serving compression springs and between the middle clamping frame part 45 and that on the tool side of the plastic tape 14 seated plate 46 also arranged on the centering rods 28 and as Resetting elements serving compression springs 48 held at a mutual distance. When approaching the These plates 44, 45, 46 are fixed to the mold carrier 31 with the plastic band 14 being clamped pressed together. To clamp the plastic band 14, the middle clamping frame part 45 and wear the plate 46 opposing clamping beads 49.

To form the separating device 50, the plate 46 arranged on the tool side is provided with a central circular section 51 provided, the opposite of the respective side surface of the mold carrier 31 protruding opening edge 34 of the molding tool 32 with play receives the rear The peripheral edge of this circular section 51 forms the separating element 52 cooperating counter-element is a separating element carrier 53 attached to the guide piece 29, the outer front peripheral edge of which forms the separating element. In the example shown, the separator support is 53 held by the rear stop plate 44 and takes in its interior Stretching aid 41 on.

Below the actual thermoforming device 30 is a pull-off device 60 for the remaining tape 14a arranged, which transfers the remaining tape into a reduction device 70. The crushed plastic material can from there, as indicated by the line 71, returned to the extruder press 11 will. The thermoforming device 30 also has a device 80 for collecting and transporting away of the moldings ejected from the molds 32. The rotary adjustment of the mold carrier 31 takes place in the example shown by means of a control device (not shown) switched electric motor 82, which at the same time operates the puller 60. The Kubeltrieb 39 is driven by an electric motor 83 also switched by the control device.

The operation of the thermoforming device described above is as follows:

During the transport step, i.e. the downward movement of the Dancer roller 25 and the gripper device 26 also the motor 82 switched on. This is at the same time with the feeding of a new strip section to the thermoforming device 30, the remaining strip section 14a of the previous thermoforming process deducted. In addition, the mold carrier 31 is in Direction of arrow 31a rotated by 90 °, so that the previously upwardly directed molding tool 32 is now the Plastic tape 14 is compared. The central control device can be connected to the crank mechanism 39 in this way be connected that shortly after the end of the feed step of the crank mechanism 39 the mold carrier 31 into contact with the plate 46 on the mold tool side. The opening edge 34 of the The tool 32 extends into the circular section 51 of the plate 46. The thickness of the plate 46 is

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within the clamping bead 49 equal to the height of the opening edge 34, so that the end face of the Tool 32 in the plane of the rear surface of the plate 46 within the clamping bead 49 sets. the Springs 48 are much weaker than springs 47. As a result, plate 46 is initially clamped of the plastic tape 14 is pressed against the central clamping frame part 45. At that moment, becomes Initiation of the actual thermoforming process of the pressure cylinder 42 of the stretching aid 41 from the central control device switched on, so that the stretching aid 41 the jammed area of the The middle part of the plastic band 14 pushes it into the cavity of the molding tool 32. At the further rotation of the Kubeltriebes 39, the two plates 45 and 46 are pressed together The spring 47 is displaced along the centering rods 28 until the central clamping frame part 45 is formed Plate against the stop plate 44 places. During this movement, the end face of the separating element carrier comes first 53 in contact with that which has already been largely pulled out by the stretching aid 41 Plastic band 14. The end face of the opening edge 34 on the molding tool then presses the plastic band in the edge area surrounding the molding against the end face of the separating element carrier 53, so that the space surrounded by the separating element carrier 53 is on the side facing the plastic strip 14 is sealed. When the support rod of the stretching aid 41 is sealed by the rear support plate of the separating element carrier 53 is guided, can now in the interior of the separating element carrier 53 by means of compressed air an overpressure can be generated which, together with the vacuum applied to the mold, the complete Forming the molding causes.

This mutual end-face support of the molding tool 32 and the separating element carrier 53 takes place before the middle plate 45 reaches the stop plate. In the case of the further from the crank mechanism 39 caused movement of the mold carrier

31 towards the plastic strip 14 is therefore the molding tool 32 against the action of the springs 33 in the interior of the mold carrier 31 shifted. The separating element carrier 53 runs into the Section 51 of the plate 46 and separates the molding along the peripheral edge with its cutting edge 52 from the surrounding material. Despite this cutting out ;; can be the one explained above complete molding process by means of compressed air can be continued as long as the molding tool is

32 and the separating element carrier 53 are supported against one another while pinching the edge of the molding, ie even during the first part of the horizontal return movement of the mold carrier 31.

When the mold support 31 is at least so far back that the centering holes 35 the Centner rods 28 have released and the opening edge 34 of the molding tool 32 from the When the circular section 51 of the plate 46 has emerged, the next feed step for the plastic strip 14 can take place can be initiated by the central control device. The process explained above is then repeated.

Compared to the embodiment described above, changes can easily be made will. For example, the mold carrier 31 could only be used for the intermittent Rotary movement be mounted on the machine frame 27, while the guide piece 29 with the on him attached parts of the thermoforming device and the separating device 50 by means of the crank mechanism 39 is moved horizontally back and forth. One could possibly also move the horizontally back and forth in this way te mass reduce, but would have a large lateral displacement of the plastic band 14 in chew to take.

For this purpose 2 sheets of drawings

Claims (7)

Patent claims: 1. Thermoforming device for producing moldings, in particular thin-walled moldings great depth from a relatively thick plastic band, in which the plasticized plastic band is gradually passed through a forming station, in which a possibly as a multiple tool formed molding tool on one and the associated counter-molding! on the other side of the to be deformed part of the plastic tape can be moved perpendicularly against this, with the Form tool and the counter-form part each have a separating element for cutting out the form tool taken over and molded part of the plastic tape are added and the molding tool in a position away from the plastic belt for releasing the moldings outside of the Forming station is movable from this, thereby characterized in that the separating elements (52, 53) on separate, from the molding tool (32) and Counter-molded part (40) separate separating element carriers, each arranged at a circumferential distance from this (46, 53) are attached, which always remain in the forming station on both sides of the plastic tape (14) can be moved vertically against this. 2. Thermoforming device according to claim 1, characterized in that on the mold side of the plastic band (14) arranged separating element carriers (46) as parallel to the band path Plate (46) is formed with a central circular section (51), in which the molding tool (32) with its opening edge (34) can be inserted with play, and the peripheral edge (52) of the circular segment (51) is a separating edge. 3. Thermoforming device according to claim 2, characterized by a about a horizontal axis rotatable mold carrier (31) with two or more mold tools (32) or sets of Forming tools, in which in each case a forming tool (32) with its Opening edge (34) or the forming tools of a set the circular segment (51) or the circular segments face the vertically arranged plate (46). 4. Thermoforming device according to claim 2 or 3, characterized in that the in the Circular section (51) of the plate (46) gripping the opening edge (34) of the molding tool (32) approximately equal to the thickness of the plate (46) around the circular segment (51) and the molding tool (32) by hitting the separating element carrier (!> 3) on its opening edge (34) against the action of a Resetting element (33) and the mold carrier (31) can be pushed in and that holding means for Retention of the mold (32) are provided in the mold carrier (31). 5. Thermoforming device according to claim 4, characterized in that on the mold side of the plastic band (14) arranged plate (46) of the separating device by the molding tool (32) or its carrier (31) against the action of a restoring element (47, 48) against a frame (27, 29) carrying the separating element carrier (53) is displaceable. 6. Thermoforming device according to claim 5, characterized in that the on the molding The plate (76) of the separating device (50) arranged on the fabric side of the Kunststcffbandes (15) on its dem Plastic band (14) facing side is also designed as a clamping frame part (49), its associated second clamping frame part one arranged on the other side of the plastic band Plate (45) is displaceable by means of the first clamping frame part against the force of a spring (47) is. 7. Thermoforming device according to claim 6, characterized in that the second clamping frame part (45) has a central circular section through which the separating element carrier (53) with its end face on the opening edge (34) of the molding tool (32) and with its cutting edge in the circular section (51) of the plate (46) runs.