DK144328B - MACHINE FOR HEAT FORMING ISAER THICKWALLED FORMULAS WITH GREAT DEPTH FROM A RELATIVE THICKNESS FORM - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a machine for hot forming, in particular, thin-walled moldings of great depth from a relatively thick molding belt, in which the plasticized molding belt is progressively passed through a hot forming apparatus, in which an optional molding molding tool is inserted perpendicular to the molding belt. and an associated mold is adversely opposed to the other side of the strip, with the molding tool and the mold forming a separating mechanism for cutting the molded portion of the strip from the rest of the strip and wherein the molding tool is arranged to be movable away from the plastic band for ejection of the mold body.

From the specification of German Patent Specification No. 1,166,455, a machine of this kind is known in which the separator mechanism comprises a knife ring fixedly connected to the end face of the molding tool, while an annular counter knife is attached to the mold. However, with such a separating mechanism, a clean cut of the shaped portion of the plastic strip from the other portion of the strip can only be achieved if either the plastic strip is strongly cooled and thus suitable for o-cutting or if the two blades fit exactly into each other and thus not between them forms a cutting slot in which hot plastic material can deposit. However, this latter condition cannot be fulfilled in practice, because of the greatly different temperatures of the molding tool and the counter molding, it is necessary to have a fairly wide gap between the two knife means. When processing a relatively thick plastic band, which is still quite hot and thus semi-fluid in its interior, the plastic will safely accumulate plastic in such a cutting slot, so that no clean cut can be obtained. In machines of the kind described, where the molding tool takes up the formed part of the plastic strip and after this part is separated from the other strip from the hot forming device, it is essential that a completely clean cut occurs, as there is otherwise danger in that the molded part of the belt, upon removal of the molding tool from the belt, is stuck to the other part of the belt and thereby 10 is partially or completely pulled out of the mold. In view of this, the invention aims to design the separating mechanism such that, regardless of the temperature differences between mold tool and mold, and despite the fact that the interior of the molding tape is still semi-liquid, a clean cut of the shaped part of the tape can be obtained from the other part of the mold. band.

This is achieved by the invention in that the cutting edge and punching cutter of the separating mechanism are fixedly fixed to some of the molding tool and counter mold, and radially around these arranged machine parts which are arranged inside the hot forming device to be moved perpendicular to the molding belt from each side of this.

Hereby the cutting gap can be made sufficiently narrow so that a clean cut of the shaped part of the strip is obtained from the other part of the strip, even though its inner 25 is still semi-liquid, so that when removing the molding tool from the strip is not formed "bridges" of material between the formed part of the tape and the other part of the tape.

According to the invention, a simple design of the separating mechanism can be achieved in that the part of the separating mechanism arranged on the side of the molding belt is formed as a strip with a strip parallel to a circular opening for introducing the molding tool with its opening edge part with a certain clearance. , the circumferential edge of the opening forming a cutting edge.

In order to obtain a suitable period for cooling the formed mold bodies before their ejection from the mold, the invention may have a rotary axis rotary mold tool carrier with two or more mold tools or 5 sets of mold tools which mold tool carrier is adapted to be capable of assume a plurality of angular positions, in each of which a molding tool or molding set with its edge portion is adjacent to the circular opening or circular openings in the vertically arranged plate.

According to the invention, the structure may be designed such that the molding tool engaging in the opening in the plate has approximately the same height as the thickness of the plate along the edge of the opening, and that the molding tool is operable against the effect of a reset member by impacting a molding tool carrier. separating means against the edge of the molding tool, and that retaining means for retaining the molding tool are present in the molding tool carrier. This ensures that the pressure between the mold and the mold is always given the correct value as determined by the resetting means and that the molding tool can be removed from the plastic strip during the cutting of the molded part from the rest of the strip.

According to the invention, the structure can be further designed such that the plate arranged on the molding tool side of the molding tape by the molding tool or the molding tool carrier is slidable towards a separating mechanism part carrying machine frame frame against the effect of resetting means. This ensures a constant abutment pressure between the molding tool and said plate in the separator mechanism during the cutting operation.

According to the invention, a secure retention of the plastic strip during the shaping and cutting of the molded part can be achieved by the plate arranged on the molding tool side of the plastic strip of the separating mechanism on the side facing the tape is also designed as a gripping frame part for the strip. if the gripper frame member arranged on the other side of the belt is constituted by a plate arranged to be displaceable by means of the first gripper frame member against the action of a spring.

According to the invention, in order to make the cutting function of the separating mechanism completely independent of the holding function of said gripper frame members, the construction may be designed such that the second gripper frame member has a central circular cut-off for passage of the separating mechanism part before its interaction with the cutting edge of the opening in the plate.

An embodiment of the invention will now be described in more detail with reference to the schematic drawing, in which FIG. 1 is a side view of a machine according to the invention; and FIG. 2 is a sectional view taken along line II-II of FIG. First

In the example shown in the drawing, the machine is made up of two units, namely a tape making unit 1 and a tape processing unit 2. The tape making unit comprises an extruder 11 which e.g. may be configured as a auger extruder and may be disintegrated, preferably granulated plastics material through its filling funnel 12. At the outlet of extruder 11, a belt pressing device 13 is provided in the form of a wide slit nozzle - hereinafter referred to as the wide slit nozzle 13. receiving the thermoplastic resin material which has been extruded into the extruder 11 under the influence of pressure and temperature, the wide slit nozzle 13 delivering this material as a resin band 14 substantially at the extrusion temperature.

The tape making unit 1, as in FIG. 1, shown in the simplest possible design, may comprise additional extruders for thermoplastic materials of various kinds, which extruders also supply the wide slit nozzle 13 and for this purpose are connected to the neck 15. located between the extruder 11 and the long slit nozzle 13. a plastic band 14 is made up of two or more layers of different thermoplastic materials or materials which have been pre-treated in different ways and which may, for example, be of different color. Similarly, a plastic band 14 may also be made which is coated on one or both surfaces with a thin plastic coating 10, e.g. a coating having a content of means against electrostatic charging of the plastic surface. However, it is also possible to make the plastic strip with one or two thin surface coatings of plastic material which differ from the plastic material of the support layer, e.g. a plastic strip whose carrier layer is made of impact-resistant polystyrene and which is coated on one or both surfaces with polycarbonate base plastic.

Within the scope of the invention, the plastic tape manufactured in the tape manufacturing unit 1 may have a relatively large thickness, e.g. of 3 mm or more. However, it does not exclude that with the machine shown, thinner plastic bands can be manufactured and processed, e.g. with thicknesses from 0.5 to 2 mm.

The plastic band 14 produced in the tape making unit 1 is delivered in a warm state, ie. closest to the extrusion temperature, to a stabilizer and cooling device 22 located at the entrance of the tape processing unit 2. The distance between the output of the wide slit nozzle 13 and the input of the stabilizer and cooling device 22 can be readily adjusted according to the needs at all times, as the belt processing unit 2 can be driven back and forth on wheels or rollers 21.

In the example shown, the stabilizing and cooling device 22 is equipped with three cooling rollers 23a, 23b and 23c. As indicated in the broken line, the cooling rollers 23b and 23c can be adjusted across the direction of movement of the plastic strip 14 so as to change the angle of wrapping with which the plastic strip 14 is in heat conductive contact with the cooling rollers 23a, 23b. and 23c while running over these. By means of the stabilizing and cooling device 22, a thin surface area of the band 14 is now cooled and made somewhat firmer, while the material in the inner areas of the band 14 between these surfaces is allowed to remain substantially at the extrusion temperature and in the plastic state. .

From the stabilizer and cooling device 22, the plastics belt 14 runs to a mechanism 24 which, vertically from top to bottom, advances the plastics belt stepwise to the hot forming apparatus, which includes a roller 25 and a cooled gripper 26 which can be moved upwards and downwards between them in full. dashed upper position and the lower position drawn in dash-dotted lines 15.

The gripper 26 is designed to engage across the plastic band 14 with molded elements. Hereby the gripper 26 is positioned in relation to the hot forming device in such a way that the parts of the belt 14, which are touched by the molded parts and thereby cooled, will lie in the belt residual part 14a, ie. between the band regions formed in the hot forming device. The gripper is made up of two parts which grip the band 14 between them. As the gripper moves downwards, these two parts are pressed against each other so that they hold the plastic band between them, while in the upward movement the parts of the gripper 26 are spaced apart so that they do not touch the belt 14.

The riding roller 25 and the gripper 26 are moved upwards and downwards in step and so that the movement of the riding roller upwards takes place continuously, corresponding to the continuously applied belt 14, ie. at half its feed rate. The downward movement of the roller 25 takes place simultaneously with the downward movement of the gripper and in steps corresponding to the length of the strip which is processed in each workflow in the hot forming device 30.

7 U4328 1 Under the gripper 26 is placed the actual hot forming device 30, to which the plastic band as mentioned above is applied stepwise vertically from above. This hot forming device 30 is characterized by such an arrangement of the molding tools and their auxiliary devices that the mold tool part which is to be provided with the plastic band is arranged horizontally opposite this. Furthermore, the hot forming device 30 comprises a mechanism for separating the manufactured joint bodies from the plastic strip.

10 As shown in the drawing, the hot forming device 30 comprises a molding tool rotatable about a horizontal axis, which in the example shown has four molding tools 32 which are spaced at 90 ° to each other, calculated in the direction of rotation of the molding tool 31. For convenience 15, single-mold tools are shown in the drawing, but it is preferred that multiple-mold tools be used instead, so that a plurality of mold bodies can be produced for each operation of the hot forming device. 2, each of the four molding tools 20 is slidably mounted in the molding tool carrier 31 and may be displaced inwardly towards the center axis 36 against the action of springs 33. In the interior of the molding tooling 31, devices not shown which are arranged to hold the molding tools are arranged. 32 in the inserted position 25 for a predetermined period, e.g. for ejecting the mold body, at least until the mold tool carrier 31 has reached its horizontal starting position. In this way, after the completion of a forming and punching operation, the mold bodies are prevented from being pushed back into the residual strip.

In the embodiment of FIG. 2, each of the die forming molds 32 protrudes from the respective face surfaces of the die carrier 31 with its rim portion 34 surrounding the die opening. On each side of the individual molding tools 32 (or multiple molding tools), the molding tool carrier 31 has on each side surface at least one, in the example shown two on each side of the molding tool 32, centering holes 14 with which the molding tool carrier 31 in its movement against the plastic belt runs onto centering pins 28 which are mounted on the machine frame 27 of the belt processing unit 2. The mold tool carrier 31 is fixed in a support frame 37 5 and is pivotally mounted therein around a horizontal axis 36 which is parallel to the vertical guide belt 14 fleet.

In the example shown, this support frame 37 is attached to two sliding rods 38 which, for the purpose of a horizontal reciprocating movement of the mold tool carrier 31, are connected to a crank drive 39. Instead of this crank drive, the sliding rods 38 can also be moved forward and back using pressure cylinders, which are appropriately controlled.

The two sliding rods 38 are mounted for sliding along their horizontal and perpendicular to the longitudinal axes of the vertical guide belt 15, which are mounted in a guide carrier 29 fixed in the machine frame 27 which also carries them parallel to the longitudinal axes of the sliding rods 38. positioning centering pins 28.

Also provided on the guide support 29 are the auxiliary devices of the molding tools 20 and the mechanism for separating the molding bodies from the rest of the belt. These auxiliary devices and the separating mechanism are only made in one copy, common to the four molding tools 32. In connection therewith, a molding mechanism 40 is provided on the guide carrier 29, which is constituted by a molding 41 adapted to the molding tool 32 (or by a multiple molding tool corresponding to number of counter molds) and a pressure cylinder 42 arranged to displace the counter mold 41 horizontally into the opposite mold tool.

Further, on the centering pins 28, one of three plates comprising gripper frame 43 for the plastic band 14 is arranged.

This gripper frame includes a rear abutment plate 44, a middle gripper plate 45 and a front gripper plate 46 facing the mold tool 31. The abutment plate 44 35 is attached to the guide support 29, while the middle and front gripper plates 45 and 46 are slidable along the centering pins 28. By means of pressure springs 47 arranged on the centering pins 9 between the impact plate 44 and the middle gripping plate 45 and also on the centering pins 28 located between the middle and the front gripping plate 45 and 46 respectively, the three plates 5 are spaced apart, but by pressing the mold tool carrier 31 they are pressed together firmly against the effect of the springs 47 and 48 during the squeezing of the molding belt 14, during the displacement of the molding tool carrier 35 with the centering holes 35 on the centering pins 28 abutting the front gripping plate 46 with its respective side surface.

For gripping the plastic band 14, the middle and front gripping plates 45 and 46 respectively bear opposite gripping frame members in the form of gripping rolls 49.

To form the separating mechanism 50, a circular opening 51 is formed in the front 15 gripping plate 46 which, with clearance, occupies the rim portion 34 of the molding tool 32 which protrudes from the respective side surface of the molding tool carrier 31. The rear circumferential edge of this opening 51 works hereby as a cutting edge 52. The cutting edge 52 is arranged to cooperate with a punching knife 53 fixed against the guide support 29, which in the illustrated example is held by the rear abutment plate 44 and in its interior receives the counter mold 41.

Under the actual heat forming device 30, a pull-out mechanism 60 is provided for the belt remnant 14a. This pull-out mechanism consists in the example shown of an intermittent driven pull-out roller 61 and a counter-roll 62.

By means of this extraction mechanism 60, the belt residue is transferred to a disassembly device 70 arranged in the belt processing unit 2, which is shown schematically in FIG. 1. In this disintegrating device 70, the strip residue can be converted into grain material which can be immediately returned to the filling funnel 12 of the extruder 11, as indicated by line 71. In the hopper 12, the recycled material as indicated by arrow 72 , mixed with new raw material. However, it is also possible to store the material coming from the disintegrating device with U6328 for later use.

As shown in FIG. 1, on the side of the molding belt 14 facing away from the molding tool carrier 31 is arranged a catching and removal mechanism 80 for the molding bodies projected from the molding tools 5. The casting of the molding is effected by means of vacuum and compressed air lines 81, which open into the molding tools 32 and are connected to vacuum and compressed air sources through valves controlled from the central machine control. The intermittent turning movements of the mold tool carrier 31 and the pull-out roller 61 are made by means of a motor, preferably an electric motor 82, which is controlled for intermittent operation by the central machine control. The crankshaft 39 is driven by a motor, preferably an electric motor 83, which is also arranged to be controlled for intermittent operation from the central machine control. However, one will preferably select a continuously running drive motor 83 and connect the central control of the continuously running and the stepwise or intermittent driven devices in the belt processing unit 2 with the crankshaft drive 39 of the crankshaft 39. In this case, regulating the rotational speed of the drive motor 83 to regulate the throughput performance of the tape processing unit 2 within sufficiently wide limits that this unit 2 can be adapted to the throughput of the extruder 25 and the wide slot nozzle 13. In addition, the throughput performance of extruder 11 is adjustable in known manner.

The machine according to the invention operates in the following way: The plastic strip 14 delivered from the wide sliding nozzle 13 is transferred to the cooling and stabilizing device 22. By setting 30 of the cooling rollers 23b and 23c, the first step of the method according to the invention is performed, namely setting the temperature on the surface of the the wide slit nozzle 13 hot and plastic strips 14 at a depth sufficient to stabilize the surface areas of the strip so that the continuously fed strip can be moved vertically and stepwise through the hot forming device. From the stabilizer and cooler assembly 22, the still continuously moving plastic belt 14 is delivered to the riding roller 25, thereby translating the continuous movement of the belt into a stepwise vertical downward motion, the rate and length of these advance steps being determined by the central machine control. The riding roller 25 is thereby supported by the gripper 26. When the hot forming device 30 is open, i.e. in the position shown in the drawing for the mold tool carrier 31 and the open position of the gripper frame 43 by the springs 47 and 48, the riding roller 25 10 and the gripper 26 are driven downward in the direction of the fully drawn arrow 26a, holding the two parts of the gripper 26 pressed against each other.

The length of this movement is adapted to the vertical length of the belt piece held by the gripping beads 49 of the gripper frame 43, and in addition to the small length 15 constituted by the belt piece affected by the transverse strips 26 of the gripper 26. From its lower position in dash-dotted lines, the roller 25 is moved back to its upper position corresponding to the continuous supply of the plastic band 14. The two parts of the gripper 26 are moved in the lower position, with dash-20 dot lines. and from the band 14, and moved upwards, as shown by the arrow dotted line 26b, back to the initial position.

By means of the central control device, the motor 82 is also switched on during the advance movement, ie. the riding roller 25 25 and the downward movement of the gripper 26. Hereby, the tape residue piece from the previous hot forming operation, at the same time as the addition of a new tape piece to the hot forming device 30, is withdrawn from the hot forming device 30. In addition, the mold tool carrier 31 is rotated 90 ° in the direction of the arrow 31a so that the molding tool 32 which previously turned upwards now comes in position next to the plastic band 14.

The central control device may be connected to the shaft 84 of the crankshaft 39 in such a manner that shortly after the completion of the feeding step, the crankshaft 39 35 pulls the mold tool carrier 31 into abutment against the front gripping plate 46. The rim portion 34 of the tool 32 thereby extends into the opening 51 in the front gripper plate 46. Within the gripper bead 49, the thickness of the front gripper plate 46 is equal to the height of the rim portion 34, so that the end surface of the tool 32 aligns with the front gripper plate 46 rear face within the gripper bead 49.

Since the springs 48 are substantially weaker than the springs 47, the front gripping plate 46 is first pressed against the middle gripping plate 45 first and during squeezing of the plastic strip 14. At the same moment, the actual hot forming operation is started by engaging the pressure cylinder 42 of the counter mold 41 central control means such that the counter mold 41 10 pushes the middle portion of the clamped portion of the belt 14 into the cavity of the mold tool 32. Upon further turning of the crank 39, both the gripping plates 45 and 46 are displaced along the centering pins 28 during compression of the springs 47 until the middle gripping plate 45 abuts the abutment plate 44. In this movement, the end face of the punching knife 53 first comes into contact with the plastic band 14, which to a large extent has been pulled out by means of the mold 41. Immediately after, the end surface of the molding tool part 34 of the molding belt in the area surrounding the mold body presses against the end surface of the punch knife 53, so that the space surrounding the punch knife 53 is sealed to that of the strip. 14 facing side. If the supporting rod of the counter mold 41 is fluid tightly passed through the supporting plate of the punching knife 53, a pressure in the space within the punch knife 53 can now be generated by compressed air, which together with the vacuum supplied through the supply lines 81 in the mold tool 31 causes a complete forming of shaped body.

The molding tool 32 and the punching knife 53 abut each other in the aforementioned manner before the middle gripping plate 45 reaches the impact plate 44. In the further movement of the molding tool 32 by means of the crank drive 39 towards the belt 14, the molding tool 32 is therefore displaced. against the action of the springs 33 into the interior of the mold tool carrier 31, the punching knife 53 running into the opening 51 of the front gripping plate 46, thereby separating the mold body from the surrounding material along the cutting edge 52. In spite of this cutting process, it can The above-mentioned complete molding operation by means of compressed air is still continued as long as the molding tool 32 and the punching knife 53 abut each other, ie still during the first part of the horizontal return movement of the molding tool 31. The vacuum applied through the supply line 81 is maintained in all cases even after the mold tool carrier 31 has returned to the one shown in FIG. 2.

When the molding tool carrier 31 has been guided at least so far back that the centering holes 35 have been released from the centering pins 28 and the molding part 34 of the molding tool 32 has emerged from the front gripping plate 46, the next conveying step of the belt 14 can be started by means of 15 the central control device. Hereby, as indicated above, the molding tool carrier 31 is rotated 90 ° so that the upwardly extending molding tool is in position against the belt 14. The molding molding 32 which is worked upwards is hereby turned downwards. Hereby, the connection of vacuum 20 through the supply line 81 is still maintained so that the mold body received in the molding tool 32 remains in the molding tool and cooled therein after the hot molding. Only when the next hot forming operation is completed and the mold tool carrier 31 is turned another 90 °, the supply line 81 is disconnected from the vacuum and connected for a moment to a compressed air source, whereby the now cooled mold body is ejected from the mold tool 32 and delivered to the capture and discharge device 80 .

Changes can be made without delay in relation to the embodiment described. For example, the mold tool carrier 31 could only be housed in the machine frame 27 for the aforementioned intermittent pivotal movement, while the guide support 29 and the portions of the hot forming device and separator 50 moved horizontally back and forth by crank gear 39. In this way, some reducing the horizontally reciprocating mass, but at the expense of a greater lateral displacement of the plastic band 14.

If desired, the duration of the cooling of the mold bodies in the mold tool 32 can be extended by aligning the mold tool carrier 31 to rotate stepwise opposite to the arrow 31a, and by placing the capture and removal device 80 for the mold bodies 85 below the mold tool carrier 31. drop, the mold bodies will be cooled further with the duration of two consecutive hot forming operations. It is also conceivable that the mold tool carrier 31 is formed with more than four mold tools and a corresponding number of working positions. On the other hand, it is also conceivable that the mold tool carrier 31 is designed with fewer, e.g. three or two molding tools 32 (optionally 15 multiple molding tools), and with a correspondingly smaller number of working positions.

Claims (4)

15 144328 A machine for hot forming especially thin-walled mold bodies (85) of great depth from a relatively thick plastic band (14), in which the plasticized plastic band (14) is gradually passed through a hot forming device (30), a formed molding tool (32) is inserted perpendicular to the molding belt (14) and an associated molding (41) is moved in the opposite direction to the other side of the belt, with a separating mechanism (50) belonging to the molding tool (32) and the molding (41) being arranged. for cutting the portion of the strip (14) formed by the molding tool (32) from the rest of the strip (14), and wherein the molding tool (32) is adapted to move away from the molding strip (14) for ejecting the molding body (85) , characterized in that the cutting edge (50) of the cutting mechanism (50) and the cutting knife (52,53) 15 are fixedly fixed to some of the molding tool (32) and the counter mold (41), and radially outside these arranged machine parts (46,53) which inside the thermoforming device (30) is arranged to be moved perpendicular to the plastic band (14) from each side thereof. Machine according to claim 1, characterized in that the portion (46) of the separating mechanism (46) arranged on the side of the molding tool (32) of the separating mechanism is formed as a parallel plate (46) with a circular opening (51) for insertion. of the molding tool (32) with its opening edge portion (34) 25 having a certain clearance, the circumferential edge (52) of the opening (51) forming a cutting edge. Machine according to claim 2, characterized in that a molding tool rotatable about a horizontal axis (31) with two or more molding tools (32) or a set of molding tools, which molding tool carrier (31) is arranged to take up several angular positions, in each of the said molding tool (32) or molding tool set having its edge portion (34) adjacent to said circular aperture (51) or said circular apertures in said vertically arranged plate (46). Machine according to claim 2 or 3, characterized