DE10218486B4 - Thermoforming plant for the production of moldings from plastic film, and process for their preparation - Google Patents

Abstract

Thermoforming plant (1) for the production of molded articles from plastic film (50), such as cups, containers, lids, food wrappers or the like, with a forming station having a two-part mold (20),
The two-part forming tool (20) having an adjustably lockable upper tool table (28) with an upper tool (30) with pre-stretchers (92) movably mounted therein and a movable lower tool table (30) with a lower tool (32) with cavities,
- wherein the movable lower tool table (30) guided by means of a guide device (42) and by a first drive means relative to the upper tool table (28) on this and is movable away therefrom,
- Wherein the upper tool table (28) has a first associated with him drive means (26) for setting up the upper tool table (28) in its position relative to top dead center of the lower tool table (32) in coordination with the mold to be produced in each case, and
- wherein the upper tool table (28) has a second drive means associated therewith (88) for driving the in the ...

Description

The The present invention relates to a thermoforming plant for production of moldings made of plastic film, such as cups, containers, lids, food packaging or the like, with a two-part mold having Forming station, according to the preamble of claim 1, and a method for producing such shaped bodies according to the preamble of claim 7.

Thermoforming machines are known in different variants and embodiments in practice become. This is for the preparation of container-shaped article or molded body thermoplastic used a two-part mold. A mold half, the so-called upper tool, is attached to the upper tool table and with this usually adjustable lockable with the frame or frame of the thermoforming system connected, so that the upper Tool can be adjusted to the respective molded body. The other half of the mold, the so-called lower tool, is movable in the frame or frame led the thermoforming system.

To the Molding of the moldings are the mold halves, So the upper and the lower tool, in a facing each other closed position. Between the upper and the lower tool is a common one preheated and thus arranged well plastically deformable plastic film, which usually in the form of a film web of a supply roll intermittently supplied becomes.

At the Deep drawing process is the plastic film between the top and clamped the lower tool and thus fixed in its position. Then the plastic film passes through the pre-stretchers of the upper tool into the cavities of the lower tool, while the edge of the shaped body to be produced continues between the is held by clamping upper and lower tool. By Generation of a negative pressure in the cavities or by blowing in Air, the film lays on the inner walls of the cavities in the lower tool and thus takes the desired Shape.

To adequate cooling the plastic film is made by the contact with the possibly actively cooled tool surface the separation of the moldings from the plastic film. For this, the lower tool is about the amount of the film thickness upwards emotional. Corresponding cutting edges of the two-part mold cut the individual moldings out of the film web. The remaining one Foil grid will turn often cyclically fed to a take-up unit.

to Removal of the moldings from the cavities The lower tool will then move away from the upper tool moved while pivoted about its longitudinal axis, that the lower tool to a stacking device shows and thus the moldings of the Stacking device to be handed over can.

Examples of the above-discussed, known from practice thermoforming plants are, for example in the US 6,135,756 A or the DE 33 46 628 A1 described.

These However, known thermoforming plants have the essential economic Disadvantage on that with it only low clock frequencies, for example, up to about 30 clocks can be realized per minute. higher Clock frequencies are without damage the moving components not possible. These low clock frequencies, however, are in the face of today's prevailing high cost pressure is no longer acceptable.

Farther disadvantageous are those used in the known thermoforming systems Drives for the in the upper tool movably arranged Vorstrecker, there with this also only low clock frequencies, for example until about 30 cycles per minute can be realized. Furthermore, at the known thermoforming the lack of accuracy in adjustability or adaptability of the upper tool with respect to the manufactured moldings disadvantageous.

The in the DE 33 46 628 A1 described thermoforming works in detail with a two-part mold, the upper tool fixed to the frame and the lower tool is designed to be movable. The lower tool is aligned for closing or opening in a combined lifting and pivoting movement to the upper tool and away from it and at the same time to a stacking device and oriented away from this back to the upper tool. The lifting and pivoting movement of the lower tool is generated by a cam toggle joint gearbox. The lower tool should thus be moved vertically and simultaneously pivoted about its own longitudinal axis.

The at the time of the DE 33 46 628 A1 known thermoforming system used combination of toggle joint mechanism in conjunction with a cam drive is designed very complex. In this case, the cam disk drive as such already has the systematic disadvantage that only limited forces can be transmitted. In addition, with a cam discs Drive no high clock frequencies feasible. In addition, cam drives tend to wear quickly, so that they must be serviced frequently, which drives the operating costs of such a thermoforming unacceptable in the air. In addition, the thermoforming system discussed herein according to the DE 33 46 628 A1 with their complex toggle joint mechanism on another group of components, which also allows system only low clock frequencies.

Further information on the design of the drive of the pre-stretchers are the DE 33 46 628 A1 not to be taken. Consequently, it can be assumed that the pretensioner drive discussed there no longer permits higher clock frequencies than the drive for the lower tool whose clock frequency has already been determined to be too low.

The thermoforming plant according to US 6,135,756 A also has a two-part molding tool in detail. The guide means is also combined here with the drive means of the lower tool table or the lower tool and generated by means of a cam crank mechanism a combined lifting and pivoting movement of the lower tool, wherein two respectively arranged on the outer end faces of the lower tool cam crank mechanism are present. In this case, the lower tool on each of its outer sides three pins, which run in the frame-fixed associated Nutkurven. These groove curves have an extremely complex geometry and are designed so that the lower tool when opening the mold from the upper tool moves downwards and can be pivoted to orient it to a stacking device and to be able to pivot away from this again. Since the complex geometry of the groove curves is not suitable for transmitting the forces necessary for separating out the molded articles from the plastic film, additional cams are provided with which the forces necessary for this purpose are to be transmitted. The achievable removal process still remains a cutting or squeezing. Of a punching can not be spoken.

apart of which are with the geometrically complex and very difficult to each other tunable groove cam guides ruled out the high clock frequencies demanded today.

The drive of the pre-stretchers is at the US 6,135,756 A described as a combination of rack and gear. Thus, the required for economical operation of a modern thermoforming system high clock frequencies are not feasible. Because to achieve a permanently repeatable high clock frequency not only requires high clock frequencies when closing and opening the mold, but also the lifting movement of the pre-stretchers must be increased in parallel to at least the same extent, so that the pre-stretchers can be operated in the same cycle as the mold ,

Besides are known from practice Vorstreckerantriebe in which the pre-stretchers are driven by means of ball-roller spindles. With Such ball-roller spindles are the required high clock frequencies unavailable. About that In addition, ball roller spindles are too expensive, maintenance-prone and have as a further disadvantage on high downtime.

As a result, It is an object of the present invention, known thermoforming systems to improve so that essential higher Clock frequencies can be achieved and thus an economical operation of such improved thermoforming plants possible becomes. It is another object of the present invention to provide an economical To propose process for the production of moldings from plastic film.

These Task is in device-technical terms by the features of claim 1.

In procedural aspects, the problem is solved by the features of claim 7.

According to the invention is a Thermoforming plant for the production of moldings from plastic film, such as Cups, containers, Lid, food packaging or the like, with a two-piece Mold-forming forming station proposed. It points the two-part mold an adjustable detectable upper Tool table with an upper tool with movably mounted therein Pre-stretchers and a movable lower tool table with a lower tool with cavities on. The movable lower tool table is by means of a guide means led and by a drive device relative to the upper tool table moving towards and away from it.

It is provided for the first time that the upper tool table has a first associated with him drive means for setting up the upper tool table in position relative to the top dead center of the lower tool table in coordination with each mold to be produced, and that the upper tool table a second drive means associated therewith for driving having in the upper tool movably mounted pre-stretchers.

Compared to the offers Vorstreckerantrieben known from the prior art the decoupling according to the invention the drive of the pre-stretchers by an appropriate provision one for this separate drive as well as another separate drive for Adjusting the upper tool with respect to the molded body to be produced before its final Determination before starting the respective production process, the advantage of this independent of both drives can be optimized from each other. Accordingly, a for the one-time adjustment or adjustment of the upper tool before Beginning of the respective production process the most suitable drive be provided, which then not necessarily in an advantageous manner at the same time also the required high clock frequencies when driving must realize the Vorstreckers but especially regarding Accuracy and repeatability of an exact adjustment of the upper Tool table selected can be. Accordingly, the separate Vorstreckerantrieb selected in relation to the required high clock frequency and in this regard be optimized.

A Although such separate optimization of the separate drives increases apparently the number of components, but offers the opposite priceless Advantage that both Drives for themselves as constructively as possible kept simple and thus finally cost-effective again can be.

Further advantageous embodiments and aspects of the present invention are the subject of the subclaims.

In a preferred embodiment the thermoforming system according to the invention is the first drive device for setting up the upper tool table designed as an electric servomotor. This offers the advantage an exact controllable speed, with its speed profile freely selectable is. With that you can both fast feed movements to overcome large adjustment paths as well as very slow and accurate delivery movements for a precise Setting up the upper tool table in the millimeter or even tenths of a millimeter range depending on the desired Accuracy can be achieved. There are also electric servomotors In every required design variant available at low cost on the market.

According to one further preferred embodiment the thermoforming system according to the invention is provided that this first drive device via a synchronization shaft with thereon arranged, for example Snails / wheels over two associated adjusting spindles cooperates, which in turn so on the upper tool table act that this in its horizontal Alignment is vertically movable up and down, so that the upper tool table is adjustable to the moldings to be produced in each case. In order to can advantageously the above-discussed advantage of freely selectable Speed profile of an advantageous servomotor in synergetic Way optimal both in large Zustellbewegungen translated as well as in small or fine Justierbewegungen become.

at a further preferred embodiment the thermoforming system according to the invention has the second drive means of the upper tool table for driving the pre-stretchers a hydraulic drive or a means an electric servomotor driven crank drive on. In both cases Particularly high clock frequencies can be achieved. These high clock frequencies can at least 40 bars, 50 bars or more bars. So beyond that in a hydraulic drive of the pre-stretchers in an advantageous manner Prestretcher forces of at least 40 kN at a working stroke of at least 120 mm and a moving mass of at least 200 kg, being the time for the painting over of the working stroke of 120 mm is less than 200 ms.

According to a further preferred variant of the second drive means, this acts via a push rod, a rocker arm and a push rod on the pre-stripper in the upper tool, which is a particularly simple constructive solution. It is provided in a particularly preferred manner that the rocker arm has a displaceably configured pivot point, so that its lever arms and, consequently, its force relationships can be adapted to the particular application. The operation of the pre-stretchers via a push rod, a rocker arm and a push rod allows the arrangement of the second drive outside the range of the upper tool especially advantageously not directly above this, so that when using a hydraulic drive not always completely excluded minor leakage of hydraulic oil is not important, since this can not drip down on the film web in an advantageous manner. In addition, in a further advantageous manner, the second drive for the pre-stretchers in transferring its driving forces via a push rod, a rocker arm and a push rod on the pre-stretchers are arranged laterally from the upper tool table, that the second drive with the upper tool table with this and thus not moved relative to this, so that the second drive controls only the movement of the pre-stretchers and thus particularly advantageous in terms of high clock frequencies can be optimized.

Further It is advantageous that the Displacement of the pivot point for setting a variable Vorstreckerhubes is usable. The fulcrum displacement results in an advantageous manner a constant stroke of the drive and a stepless adjustment of the Vorstreckerhubes, so that the top dead center of the pre-harvester remains constant and bottom dead center be adapted depending on the product or molding height can.

at a further preferred embodiment the thermoforming system according to the invention is the Vorstrecker by means of the second drive device such drivable that one Stroke of at least 120 mm or more in less than 300 ms, preferably less than 200 ms, executable is. This advantageously clock frequencies over 60 clocks per minute feasible, so that at a thermoforming plant according to the invention, for example, a crank drive for a linear guided lower Tool table provides, overall so far not as feasible believed high clock frequencies can be achieved.

The The above object is in procedural terms by the features of claim 7 solved. Here, a method for the production of moldings, such as Cups, containers, lids, Food wrappers or the like made of plastic with a thermoforming plant according to the preamble of claim 1, including the following steps comprising: a) providing a thermoforming system according to the preamble of claim 1, b) supplying Plastic film in the mold, c) clamping the plastic film d) Close of the mold by guidance of the movable lower tool table by means of the guide device and driving the same by means of the drive device such, that this is moved towards the upper tool table on this, e) manufacture the molded body with closed mold, f) opening of the mold by guide the movable lower tool table by means of the guide means and driving the same by means of the drive means such, that this moved away from the upper tool table, and g) Ejecting the moldings if necessary in a stacking device, whereby, inter alia, that the upper tool table by means of a first, associated with him drive device in its position relative to the top dead center of the lower tool table in Tuning is set up with the respective moldings to be produced, and that the in the upper tool movably mounted Vorstrecker by means of a second drive device can be driven. The associated Advantages are already discussed above with respect to the device Service. Further advantageous embodiments of the method are in the subclaims discussed.

The Invention will be described below in embodiments with reference to FIG Figures of the drawing closer explained. It shows:

1 a plan view of an embodiment of a thermoforming plant according to the invention;

2 a side view of in 1 illustrated exemplary embodiment of a thermoforming system according to the invention;

3 a side view of the drive shown for pivoting the guide rail assembly shown in FIG 1 and 2 shown variant of a thermoforming system according to the invention;

4 a section along the line XX 3 ;

5 in the 1 to 4 shown variant in a tilted operating arrangement;

6 a schematically simplified sketch of an exemplary embodiment of a drive according to the invention for actuating the pre-stretchers in the inventive thermoforming plant according to 1 to 5 ;

7 a schematically simplified sketch of an exemplary embodiment, which illustrates how the in 6 shown drive can be formed;

8th an alternative embodiment of the Vorstreckerantriebs the thermoforming according to the invention 1 to 5 ;

9 another variant of in 6 to 8th shown alternative Vorstreckerantriebe invention, with the pre-stretchers in the park position;

10 in the 9 shown embodiment of a Vorstreckerantriebes, with the pre-stretchers in the extended state; and

11 another alternative transmission structure to the in 6 to 10 shown variants of Vorstreckerantrieben.

In 1 is an exemplary embodiment of a thermoforming system according to the invention 1 shown in a view from the front. The moving assemblies of the thermoforming system 1 are in egg a frame 2 arranged. The frame 2 can be constructed, for example, in the form of steel sheet plates which have been stress-relieved. A below, that is arranged to the ground traverse 4 connects the frame plates 2 and also serves as a bed for the bearings of the crankshaft drive 6 , The crankshaft drive 6 is in the variant shown here via an electric servomotor 8th driven. Its driving force is via a belt 10 and pulleys 12 and 14 driven, especially in 2 better visible in the lateral view. The crankshaft drive 6 is in the variant shown here in relatively short lever arms 16 symmetrically mounted on both sides, wherein the lever arms 16 in turn to one on the Traverse 4 attached bearing block 18 are articulated.

In 1 as well as in 2 is about in the middle of the picture, the two-part mold 20 the forming station of the thermoforming plant 1 shown in closed condition. One in the upper part of the picture 1 and 2 recognizable traverse 24 connects the two frame plates 2 above the two-part mold 20 and serves as the basis for a drive 26 for adjusting the upper tool table 28 with the attached upper tool 30 , The drive 26 for adjusting the upper tool table 28 may be formed, for example, as a fine stroke with threaded clearance compensation. A lower tool table 32 carries the lower tool 34 and is by means of appropriately trained linear guides 36 between the swiveling guide rails 38 the pivotable guide rail assembly 40 (see. 3 and 4 ) of the guide device 42 arranged. At the bottom or at the bottom of the lower tool table 32 are ejector cylinders 44 and the upper connecting rod bearings 46 attached.

Between the upper tool 30 and the lower tool 34 of in 1 and 2 closed mold shown 20 is a chain transport 48 shown, by means of which the plastic film 50 the two-part mold 20 fed and transported away after molding and punching out of the mold body, not shown here, wherein the plastic film 50 with appropriate means in the area of the two-part mold 20 preferably bi-directionally planar tensioned.

The upper tool table 28 is in appropriately designed linear guides 52 between the frame plates 2 guided. The lower tool 34 may for example have a mounting surface of 490 mm × 1040 mm. This means, for example, four rows of eight cavities each for 32 Shaped body realized at a molding diameter of about 75 mm. This means a total punching length of all punched through edges of 7640 mm, which makes a total punching force of about 400 kN necessary.

The upper tool 30 is for example not shown spacers on the upper tool table 28 attached. Guide rails, not shown, facilitate the assembly of the tools. A thread play compensation 54 serves to compensate for game, for example, the Feinhubantrieb 26 of the upper tool table 28 , The linear guides 36 for the lower tool table 32 have a backlash-free adjustment and ensure an exact guidance of the lower tool 34 , The linear guides 52 of the upper tool table 28 have not shown in detail adjustable sliding guides on.

The below the lower tool table 32 arranged ejector drives 44 for the in 2 in a local partial section recognizable ejector 56 have two pneumatic cylinders with a stroke limitation.

The crankshaft drive 6 driven connecting rod 58 Also used as a connecting rod for the lifting drive of the lower tool table 32 can be referred to, is formed in the variant shown here in the form of a triangle or Y-shaped. The connecting rod 58 is with a first connecting rod section 60 on the eccentric shaft section 62 of the crankshaft drive 6 hinged. The two in 1 and 2 up-facing arms 64 the Y-shaped connecting rod 58 are at the connecting rod bearings 46 of the lower tool table 32 hinged. These two upper connecting rod bearings 46 are here as possible arranged such that a deflection of the lower tool table 32 as well as its own weight can be kept as low as possible. The Y-shaped connecting rod 58 has at the lower connecting rod section 60 the variant shown here advantageously only one bearing, so that already satisfies a crank mechanism.

As already stated above, the crankshaft drive 6 with a double storage in rigid version available. The related crank bearings may be split for ease of assembly. The crankshaft drive 6 is centered in lever arms 16 stored, which form a kind of double swing. This is in turn with its right side by means of the bearing block 18 on the traverse 4 stored. On the left side of this double rocker engages the punch drive 64 at. The punch drive 64 For example, it consists of a hydraulic cylinder and an associated hydraulic system, which generates a sudden punching stroke via the hydraulic cylinder, which via the double rocker 16 , the crankshaft drive 6 , the connecting rod 58 , camps 46 on the lower work convincing table 32 and thus on the lower tool 34 is transmitted.

The drive of the crankshaft drive 6 can - as already mentioned above - as a linear actuator a servo motor 8th have, via gear, timing belt, sprocket or the like in low-play design on the crankshaft drive 6 acts. The closing and opening of the two-part mold 20 then corresponds to 160 ° rotation on the crankshaft.

The already in 1 and 2 illustrated pivot lever 38 for pivotally receiving the lower tool table 32 have in the variant shown here, for example, the closer in 3 illustrated, designed as cam rollers, pivot lever side guides 66 on. The trained example as cam rollers lateral guides 66 the pivot lever 38 run on non-illustrated hardened rails and are free of play adjustable for exact guidance of the lower tool 34 ,

As a drive for pivoting the pivotable guide rails 38 the pivotable guide rail assembly 40 is on both sides of the lower tool table 32 a crank rod 68 intended. As a drive 70 for generating the pivoting movement of the lower tool 34 over the swiveling guide rails 38 can one on both guide rails 38 acting crank rod pivot drive 68 be provided, for example, by a servo geared motor 72 and a synchronizing shaft 74 is driven. These details are in 4 making a section along the line XX of 3 shows, shown in more detail.

To limit the pivoting movement in the frame or the frame 2 inside is a swivel lever stop 76 provided as in 3 shown. This stop 76 for the pivot lever 38 is for exact positioning of the lower tool 32 adjustable.

The drive 84 for setting the upper tool table 28 , which may be formed, for example, as a fine drive, not only serves for example for setting the punching stroke, but can also be used to turn on or turn off the punching stroke. Two in 1 and 2 only slightly visible threaded spindles 78 for example, via worm gears 80 via a synchronizing shaft 82 by means of a geared motor 84 driven.

In the variant shown here according to 1 to 5 can two trained example as a pneumatic bellows cylinder thread play compensation 54 About not shown pull rods the upper tool table 28 pull up to pick up the backlash between spindle and nut.

As in 2 is shown in more detail, is a Vorstreckereinheit 86 intended. The pre-tensioner unit 86 has, inter alia, in the variant shown here designed as a servomotor Vorstreckerantrieb 88 on, who has an in 2 not shown toothed belt drive and planetary roller screw, the mother by releasable couplings with the Vorstreckerplatte 90 and the pre-stretchers arranged thereon 92 is connected. In this case, the Vorstreckerantrieb also a highly dynamic servo motor 88 exhibit.

In the in 1 illustrated alternative variant of the Vorstreckerantriebs Vorvorreckereinheit 86 can this one console 94 have, as Vorstreckerantrieb a hydraulic cylinder 96 wearing. The hydraulic cylinder 96 is with the console 94 relative to the upper tool table 28 dormant with this linear shifted. The distance between the hydraulic cylinder 96 to the upper tool table 28 it always stays constant. The hydraulic cylinder 96 is through a housing 98 encapsulated, so that even with minor leaks no hydraulic oil can escape. A push rod 100 is on the hydraulic cylinder 96 hinged, as in 1 shown, and is with her, the hydraulic cylinder 96 opposite end in the variant shown here right end of a rocker arm 102 hinged. The rocker arm 102 is by means of a storage 104 held pivotally. Warehousing 104 engages on a suitable bracket in turn on the upper tool table 28 at. At the left end of the rocker arm 102 is the Vorstreckerstange 106 hinged, with the Vorstreckerplatte 90 and the pre-stretchers arranged thereon 92 communicates. The hydraulic cylinder 96 for driving the pre-stretchers 92 may include a servo controller, which is a programmable controller for the stroke of the cylinder 96 contains. The required hydraulic unit can be arranged in the machine base. The Vorstreckerstange 106 Can via a compensating coupling with the Vorstreckerplatte 90 in the upper tool 30 be connected. The housing 98 for the hydraulic cylinder 96 not only serves to catch any leaks, but can also carry the servo control and also contain sensors or the like to report any leaks occurring and have means to dissipate them. The same applies to the hydraulic lines.

As in 2 shown, the thermoforming apparatus I according to the invention can be a stacking device 108 be assigned, which the finished molded body after ejection from the Cavities of the lower tool 34 receives, stacks and leads away. The stacker 108 can do this, for example, a rake 110 have to remove the ejected molded body.

The above discussion of the 1 to 5 Reference numerals used in the following discussion of the 6 to 11 for the same elements or the same or similar acting components used analogously to simplify the description.

In 6 is another variant of the already in 1 to 5 discussed Vorstrekkerantriebe 88 shown. A crank mechanism 140 acts via a push pull rod 100 on a rocker arm 102 who is in here 6 simplified dash-dotted line is shown to clarify the second different positions, namely the one position in the execution of the working stroke and thus the lowering of the pre-stretchers 92 as well as during the return stroke, ie when lifting from the pre-stretcher plate 90 arranged Vorstrecker 92 , The rocker arm acts 102 , which is a pivot point in storage 104 tilts, which is designed transversely displaceable in the variant shown here, as the arrow 142 indicates, on the Vorstreckerstange 106 , which at the Vorstrekkerplatte 90 is articulated. By the shift 142 of the bearing pivot point 104 across to an imaginary horizontal line 144 can advantageously the hub 146 be varied and in contrast the hub 148 the Vorstreckerantriebs be kept constant. Here are the downward working stroke, the Vorstrecker 92 with the further arrow 150 and the related return stroke with the arrow 152 characterized.

In 7 is again in a schematically simplified manner in a sketch a possible embodiment of a Vorstreckerantriebs 88 drive side closer shown. The crank mechanism 140 is by means of a warehouse 154 supported on the housing side. A gearbox 156 and a clutch-brake combination 158 connect the crank mechanism 140 with a motor 160 ,

In 8th is another alternative embodiment of a pre-stretching drive 88 shown in a schematically simplified sketch. The gearbox construction is essentially the same as in 6 discussed. Instead of in 6 shown crank mechanism 140 is in 8th a hydraulic cylinder 162 provided, as for example in the in 1 to 5 discussed Hydraulikvorstreckzylinder 96 the case is. The fulcrum shift is again with the arrow 142 symbolizes. To shift the fulcrum 104 is in accordance with this sketch 8th an electric motor 164 and an adjusting spindle 166 intended.

In 9 is another variant of a Vorstreckerantriebs 88 shown in a schematic way. For power generation neither a hydraulic pre-stretch cylinder is used 96 respectively. 162 , This one is in point A with the push pull rod 100 connected. The push pull rod 100 is in turn at point B on the rocker arm 102 hinged. The rocker arm 102 is in turn at point C on the Vorstreckerstange 106 hinged. The pre-striker rod 106 in turn, in point D with the Vorstreckerplatte 90 articulated. At the Vorstreckerplatte 90 are the prefixers 92 hinged, which in turn in the upper tool 30 are mounted linearly displaceable. The upper tool 30 is at the upper tool table 28 attached. The rocker arm 102 is rotatable about point B0 in the bearing 104 stored.

At the in 9 shown Vorstreckerantrieb 88 is the hydraulic cylinder 96 respectively. 162 in front of or behind the upper tool 30 arranged. An alternative arrangement of the cylinder 96 respectively. 162 next to the tool 30 is also possible. The pre-stretchers 92 are in 9 shown in the parking position. Accordingly, the pre-stretchers 92 in the schematic sketch according to 10 shown in the extended position. For the rest, the presentation is similar 10 the in 9 shown variant of an exemplary embodiment of a Vorstreckerantriebes 88 ,

In 11 is another alternative embodiment of a Vorstreckerantriebes 88 shown. This is similar to the one in 9 and 10 shown variant, however, has an alternative lever mechanism. In this case, longitudinal holes are provided in the articulation points B and C, which allow an axial displaceability of these articulation points, so that the hydraulic cylinder 96 respectively. 162 directly on the rocker arm 102 can be hinged at point B, so that on the push-pull rod 100 can be waived. Likewise, on the Vorstreckerstange 106 are omitted, in which the former pivot points C and D coincide in common pivot point C, wherein the rocker arm 102 directly with a suitably designed shoulder or storage 168 with the pre-stretcher plate 90 connected is.

As already discussed above, for molding the cup shaped bodies, for example, the heated plastic film is discussed 50 with the help of the upper tool 30 rectilinearly displaceable pre-stretchers 92 in the mold cavities or cavities of the lower tool 34 pressed. By generating, for example, an overpressure in the upper tool 30 The film adheres to the walls of the mold cavities or cavities. The pre-stretchers 92 will be returned to their parking position (cf. 9 ) in the upper tool 30 moved back (see arrows 150 respectively. 152 in 6 and 8th ).

In order to achieve the shortest possible times for the molding of the molded body, is a Vorstreckerantrieb 88 proposed with high dynamics. For a movement cycle of the pre-stretchers 92 (Downward movement 150 and return movement 153 to the starting position), a duration of at most 300 ms, preferably at most 250 ms and particularly preferably at most 200 ms is achieved. In addition, the in 6 to 11 discussed Vorstreckerantrieb 88 able to pre-stretch the plastic film 50 to generate required forces. The sum of the individual prefixers 92 acting forces can be up to 50,000 N, depending on the embodiment.

Accordingly, the embodiment discussed above is a feedforward drive 88 with a hydraulic cylinder 96 respectively. 162 provided for generating the neces sary forces. The pre-stretchers 92 are in the illustrations according to 9 to 11 by means of a pre-stretching punch rod 170 with a bridge or the so-called Vorstreckerplatte 90 firmly connected. The stamping rods 190 run in a straight line guided in guide bushes 172 of the upper tool 30 so that the entire pre-tensioner unit 86 can be moved vertically.

The drive of the pre-stretchers 92 takes place as discussed above with the help of the hydraulic cylinder 96 respectively. 162 is - as in 1 to 5 shown - firmly with a console 94 connected, in turn, from the upper tool table 28 worn. The linear movement of the piston rod 174 is through the coupling or push pull rod 100 with the hinges A and B first on the rocker arm 102 transfer. The rocker arm 102 is - as discussed above - rotatable at the point B ₀ relative to the upper tool table 28 supported. The coupling or Vorstreckerstange 106 with the hinges C and D finally transfers the movement of the rocker arm 102 on the pre-tensioner unit 86 ,

This in 6 to 11 schematically illustrated transmission 88 can be varied in many ways. In an exemplary variant, the movement of the rocker arm 102 by a bolt and a link on the pre-tensioner unit 86 be transmitted. Likewise, the cylinder 96 respectively. 162 alternatively to the fixed connection with the console 94 opposite the console 94 only be articulated and thus kept pivoting.

Another advantage of the hydraulic Vorstreckerantriebs 88 are the high forces that can be generated with a very good dynamics. The risk of thermal overload does not exist here.

The The present invention thus provides for the first time in an advantageous manner a thermoforming plant for the production of moldings made of plastic, such as Cups, containers, Lid, food wrappers or the like, with a Two-part mold having forming station. The two-piece Mold has an adjustable ascertainable upper tool table with an upper tool with movably mounted pre-stretchers and a movable lower tool table with a lower tool with cavities on. The movable lower tool table is by means of a guide device guided and by a drive device relative to the upper tool table moving towards and away from it. Here, the upper Tool table according to the invention first time a first associated with him drive means for setting up the upper tool table in its position relative to top dead center of the lower tool table in coordination with the respectively produced moldings on. Furthermore, the upper tool table for the first time a second him associated drive means for driving the in the upper tool movably mounted pre-stretchers. Furthermore, the present proposal Invention for the first time an economical process for the preparation the molded body made of plastic film.

Provided a hydraulic drive for the Vorstrecker is provided, this can be in an advantageous manner as a so-called linear amplifier Servo be provided so that both its stroke and Speed profile independent controlled by each other and thus can be specified.

With the thermoforming system according to the invention can Plastic films of PP, PS, PE, PET, ABS or PVC are processed. The thermoforming system as a film web supplied plastic film can thereby a film web width of at least 250 mm to 750 mm at a Film web thickness of at least 0.3 mm to 4 mm. The between The upper and lower tool available mold area is at least 700 mm × 450 mm. The maximum closing force is at least 400 kN with a maximum cutting length of at least 8400 mm.

1

Thermoforming system

2

frame or frame

4

lower traverse

6

crankshaft drive

8th

electrical servomotor

10

belt

12

pulley

14

pulley

16

lever arm

18

bearing block

20

two-part mold

24

upper traverse

26

drive setting upper tool

28

upper work table

30

upper Tool

32

lower work table

34

lower Tool

36

Linear guide lower work table

38

swiveling guide rails

40

Guide rail assembly

42

guide means

44

ejector

46

connecting rod bearing

48

chain transport

50

plastic film

52

Linear guide upper work table

54

Thread-lash adjuster

56

ejector

58

connecting rod

60

first connecting rod

62

eccentric shaft

64

punch drive

66

Swing handle cornering

68

Connecting rod pivot drive

70

Rotary actuator

72

Servo gearmotor

74

Synchronizing shaft

76

Swivel bar stop

78

screw

80

worm gear

82

Synchronizing shaft

84

gearmotor

86

Pre-stretch unit

88

Pre-stretch drive

90

Prestretcher plate

92

prestretcher

94

console for Vorstreckerantrieb

96

hydraulic Pre-stretch cylinder

98

casing

100

pushrod

102

rocker arm

104

storage rocker arm

106

Pre-stretch rod

108

stacker

110

rake

140

crankshaft

142

Rotary offset

144

imaginary horizontal line

146

variable stroke

148

constant stroke

150

stroke

152

recall

154

camp

156

transmission

158

Clutch-brake combination

160

engine

162

hydraulic cylinder

164

electric motor

166

adjusting spindle

168

shoulder or warehouse

170

Pre-stretch-piston rod

172

link guide

174

piston rod

Claims (8)

Thermoforming plant ( 1 ) for the production of moldings from plastic film ( 50 ), such as cups, containers, lids, food wrappers or the like, with a two-part mold ( 20 ) having the forming station, - wherein the two-part mold ( 20 ) an adjustable ascertainable upper tool table ( 28 ) with an upper tool ( 30 ) with Vorstreckern movably mounted therein ( 92 ) and a movable lower tool table ( 30 ) with a lower tool ( 32 ) with cavities, - wherein the movable lower tool table ( 30 ) by means of a management facility ( 42 ) and by a first drive means relative to the upper tool table ( 28 ) is movable towards and away from the latter, - the upper tool table ( 28 ) a first associated with him drive device ( 26 ) for setting up the upper tool table ( 28 ) in its position relative to top dead center of the lower tool table ( 32 ) in coordination with the molding to be produced in each case, and - wherein the upper tool table ( 28 ) a second drive device associated therewith ( 88 ) for driving the in the upper tool movably mounted pre-stretchers ( 92 ), characterized in that - the first drive device for the lower tool table ( 32 ) as crankshaft drive ( 6 ) is formed, - that the lower tool table ( 32 ) together with the first drive means within the guiding device ( 42 ) in a predetermined stroke by means of a second drive means of the lower tool table ( 32 ) is raised, for generating a punching movement ( 124 . 126 ), and - that the Vorstrecker ( 92 ) by means of the second drive device ( 88 ) of the upper tool table ( 28 ) are drivable such that a hub ( 146 ) of at least 120 mm in less than 300 msec., Preferably less than 200 msec., Executable. Thermoforming plant ( 1 ) according to claim 1, characterized in that the second drive means ( 88 ) of the upper tool table ( 28 ) for driving the pre-stretchers ( 92 ) by means of an electric servomotor ( 160 ) driven crank drive ( 140 ) having. Thermoforming plant ( 1 ) according to claim 1 or 2, characterized in that the second drive means ( 88 ) via a push-pull rod ( 100 ), a rocker arm ( 102 ) and a push rod ( 106 ) on the Vorstrecker ( 92 ) in the upper tool ( 30 ), preferably by means of a displaceable ( 142 ) configured pivot point B0 of the rocker arm ( 104 ), acts. Thermoforming plant ( 1 ) according to one of claims 1 or 3, characterized in that the second drive device ( 88 ) of the upper tool table ( 28 ) for driving the pre-stretchers ( 92 ) a hydraulic drive ( 96 . 162 ) having. Thermoforming plant ( 1 ) according to one of claims 1 to 4, characterized in that the first drive device ( 26 ) for setting up the upper tool table ( 28 ) an electric servomotor ( 84 ). Thermoforming plant ( 1 ) according to one of claims 1 to 5, characterized in that the first drive device ( 26 ) for setting up the upper tool table ( 28 ) via a synchronization wave ( 82 ) arranged thereon with screws / wheels with two adjusting spindles ( 78 ), which in turn so on the upper tool table ( 28 ) that this in its horizontal orientation is vertically movable up and down, so that the upper tool table ( 28 ) is adjustable to the moldings to be produced in each case. Process for the production of shaped articles, such as cups, containers, lids, food wrappers or the like, from plastic film, by means of a thermoforming machine ( 1 ) according to the preamble of claim 1, comprising the following steps: - providing a thermoforming plant ( 50 ) according to the preamble of claim 1; - feeding plastic film ( 50 ) in the mold ( 20 ); - clamping the plastic film ( 50 ); - closing the mold ( 20 ) by guiding the movable lower tool table ( 32 ) by means of the management facility ( 42 ) and driving the same by means of a first drive means such that this relative to the upper tool table ( 28 ) is moved to this, wherein - the lower tool table ( 32 ) by means of crankshaft drive ( 6 ) formed first drive means for the lower tool table ( 32 ) is driven (118); - Production of the moldings with closed mold ( 20 ), where - in the upper tool ( 30 ) movably mounted pre-stretchers ( 92 ) by means of a second drive device ( 88 ) of the upper tool table ( 28 ) are driven in such a way that a hub ( 146 ) of at least 120 mm in less than 300 msec. is executed, and - the lower tool table ( 32 ) with its first drive device within the guiding device ( 42 ) by means of a second drive device for the lower tool table ( 32 ) for generating a punching movement ( 124 . 126 ) with a predetermined punching stroke, raised and lowered again; - opening the mold ( 20 ) by guiding the movable lower tool table ( 32 ) by means of the guide device ( 42 ) and driving the same by means of the first drive means such that this relative to the upper tool table ( 28 ) is moved away from it; - ejecting the moldings possibly in a stacking device, wherein - the upper tool table ( 28 ) by means of a first drive device assigned to it ( 26 ) in its position relative to top dead center of the lower tool table ( 32 ) is set up in coordination with the moldings to be produced in each case. Method according to claim 7, characterized in that the in the upper tool ( 30 ) movably mounted pre-stretchers ( 92 ) by means of a second drive device ( 88 ) of the upper tool table ( 28 ) are driven in such a way that a hub ( 146 ) of at least 120 mm in less than 200 msec. is performed.