Packaging machine

Abstract

The present invention relates to a packaging machine having at least one working station which has a lower and/or an upper tool, being vertically movable on lifting tables and the lifting table having

Description

[0001] The present invention relates to a packaging machine having at least one working station which has a lower and/or an upper tool, the lower tool being vertically movable on lifting tables.

[0002] Such packaging machines are well-known from the prior art.

[0003] Thus, for example, EP 0,569,937 B1 discloses a packaging machine having a working station which includes a lifting device wherein the lower tool is lifted or lowered by a toggle lever system and a piston cylinder means. However, such a lifting device requires an enormous amount of space, thereby unnecessarily increasing the length of the packaging machine. Moreover, the lifting mechanism is relatively slow and complex because e.g. two toggle levers are required to avoid tilting of the plate at the guide bars.

[0004] It was therefore the object to provide a packaging machine that would not involve the drawbacks of prior art.

[0005] According to the invention, said object is accomplished by means of a packaging machine having at least one working station which has a lower and/or an upper tool, the lower tool being vertically movable on lifting tables and the lifting table having

[0006] a vertically displaceable plate onto which the lower tool is mounted,

[0007] at least one vertical guide for said plate,

[0008] a crankshaft,

[0009] a bar, one end of which being connected rotatably about at least one axis to the plate and the other end rotatably to the crankshaft, and

[0010] a rotatable drive driving the crankshaft.

[0011] A working station in the meaning of the invention is e.g. a deep drawing, a sealing and a cutting station.

[0012] In a preferred embodiment, the bar is arranged in the center of the plate. This embodiment is advantageous in that the plate never undergoes tilting.

[0013] In another preferred embodiment, the crankshaft runs rotatably on bearings in two yokes. The yokes themselves are adjoined to the frame of the packaging machine. Preferably, the yokes are arranged transversely to the machine direction of the foil so that the length of the construction of each working station is designed to be particularly short.

[0014] Bearing the crankshaft on two yokes is advantageous in that the immense forces occurring during lifting and pressing the plate with the lower tool against the upper tool can very well be passed into the vertical guide without bending and/or tilting the crankshaft.

[0015] Preferably, the vertical guide of the plate consists of a bar, more preferably of two bars, with four bars being particularly preferred. The plate itself has at least one, preferably two guide bushings receiving the bars.

[0016] In a preferred embodiment, the yokes run on bearings preferably at the bottom end of the bars, and preferably in a vertically displaceable fashion, each one yoke being held by two bars. This embodiment of the packaging machine according to the invention is advantageous in that each working station represents an entity which can be displaced as a whole within the packaging machine, or demounted.

[0017] Advantageously, each bar has a spring element, preferably an elastomeric spring attached thereto, where the vertically displaceable yokes rest on. This embodiment of the packaging machine according to the invention is advantageous in that foils of varying thickness or with relatively large tolerances with respect to their thickness can be processed without necessitating changes in the lift adjustment. An increased foil thickness then results in a minimal increase in force. Moreover, the press-on pressure of the lower tool against the upper tool can be limited by said springs.

[0018] The crankshaft preferably is driven by an electric motor, preferably a servomotor which preferably is computer-controlled. The electric motor preferably has a gear, the power transmission between the electric motor or gear and the crankshaft preferably being effected by a toothed belt. The electric motor or gear preferably has such a high torque and such a high rotational speed that the plate together with the lower tool is lifted within less than one second, preferably within less than one half second from the bottom to the top position and vice versa.

[0019] Moreover, the electric motor or the gear at the power take-off side preferably has a retention momentum of >50 Nm, more preferably >100 Nm, so as to be capable of absorbing the forces occurring e.g. during sealing or cutting where the bar connecting the plate with the crankshaft is not in vertical position.

[0020] Preferably, the crankshaft is rotated alternately in a clockwise and counterclockwise fashion. Surprisingly, such an arrangement was found to be highly space-saving. The angle of rotation is 180° at maximum. However, the crankshaft preferably moves by an angle of rotation having precisely such a magnitude that the tool will not damage the package trough as it moves further on. In a particularly preferred fashion, the tool is lowered by such a distance that its top edge is 1-10 mm below the package trough at maximum. As a result of such lowering, a substantial reduction of the cycle time of the packaging machine according to the invention is possible.

[0021] The packaging machine of the invention is advantageous in that the vertical movement of the lower tool is carried out within less than one second. Production and maintenance of the lifting table are easy. Because the bar contacts the plate at the center thereof, tilting of the plate at the guide is excluded.

[0022] A preferred embodiment of the packaging machine according to the invention includes a means for avoiding product squeeze between upper and lower tools. Preferably, such a means involves limiting the admissible consumption of power required for the upward motion of the lower component. Is there any product between upper and lower tools, it will be compressed between the upper and the lower tool, thereby increasing the consumption of power required to lift the lower tool, and the motor control will stop the upward motion.

[0023] With reference to FIGS. 1-3, the invention will be illustrated below. These illustrations are merely by way of example and do not limit the general idea of the invention.

[0024] FIG. 1 shows a schematic side view of a packaging machine with lateral cover omitted;

[0025] FIG. 2 shows a side view (in machine direction of foil) of the lifting table;

[0026] FIG. 3 shows a side view (across the machine direction of foil) of the lifting table.

[0027] FIG. 1 shows the packaging machine of the invention in schematic view. A foil 1 is unrolled from a roll, initially passing through a deep drawing station 2 comprised of an upper tool 3 and a lower tool 4. The lower tool 4 is mounted on a plate 5 which, as indicated by the arrow, can be lifted and lowered. In the deep drawing station 2, the foil 1 is deformed to yield a package trough 6.

[0028] Thereafter, the package troughs 6 are filled with an item to be packaged, and the package troughs are sealed with a cover foil in the subsequent sealing station 10. Similarly, the sealing station 10 is comprised of an upper tool 12 and a lower tool 11, and the lower tool 11 can be lifted and lowered in the sealing station as well.

[0029] Finally, the packages are cut apart in cutting station 7. Again, the cutting station is comprised of an upper tool 8 and a lower tool 9, and the lower tool 9 can be lifted and lowered in the cutting station as well.

[0030] The lifting table, by means of which the lower tools 4, 9, 11 are lowered and lifted, is illustrated in FIGS. 2 and 3, each one permitting a different view on the lifting table. FIG. 2 shows the lifting table in lowered condition, while the lifting table in FIG. 3 has been lifted.

[0031] The lifting table has a plate 13, onto which the lower tool 4, 9, 11 is mounted. The plate is provided with two guide bushings 14 receiving the guide bars 15. On its bottom side, the plate 13 has a bearing 16, wherein the top end 18 of bar 17 is accommodated pivotably about one axis. At its bottom end 19, the bar 17 is rotatably connected with crankshaft 20 which, in turn, runs on bearings in yokes 21, 22. The yokes 21, 22 run on bearings on bars 15 in a vertically displaceable fashion, resting on elastomeric spring 26. This type of bearing allows automatic adjusting of the lift to the thickness of the foil. At the same time, it is made sure that the press-on pressure by means of which the lower tool is pressed against the upper tool does not exceed a specific maximum value. In addition, such a bearing of the yokes allows excellent adjustment of the press-on force. The lower tool and the lifting device thereof can be displaced as an entity within the packaging machine, or demounted. The crankshaft 20 is driven by the electric motor 24 via toothed belt 23. The motor is controlled in a way so as to alternately rotate the crank of the crankshaft from the highest to the lowest point and vice versa, said rotation being effected alternately in a clockwise and counterclockwise fashion. The spacing 25 is dimensioned in a way so as to correspond to at least half the depth of the deepest processable package trough on the respective packaging machine. The electric motor 24 has a gear. The electric motor or gear is dimensioned in such a way that one rotation of the crankshaft is performed in less than one second. In addition, the electric motor 24 has a retention momentum of >10 Nm, so that the gear at the power take-off side has a retention momentum of >100 Nm in order to allow absorption of forces occurring during the respective processing operation, particularly in cases where the bar 17 is not in absolutely vertical position.

Claims

1. A packaging machine, having at least one working station (2, 7, 10) which has a lower and/or an upper tool (3, 8, 12), the lower tools (4, 9, 11) being vertically movable on lifting tables, characterized in that the lifting table has

a vertically displaceable plate (13) onto which the lower tool (4, 9, 11) is mounted,

at least one vertical guide (15) for said plate (13),

a crankshaft (20),

a bar (17), one end (18) of which being connected rotatably about at least one axis to the plate (13) and the other end (19) rotatably to the crankshaft (20), and

a rotatable drive driving the crankshaft.

2. The packaging machine according to claim 1, characterized in that the bar (17) is arranged in the center of plate (13).

3. The packaging machine according to claim 1 or 2, characterized in that the crankshaft on its right and left runs on bearings in yokes (21, 22).

4. The packaging machine according to any of claims 1 to 3, characterized in that the vertical guide (15) is comprised of a bar, preferably of two bars, with four bars being particularly preferred.

5. The packaging machine according to claim 4, characterized in that each one yoke (21, 22) runs on bearings on two bars (15) in a vertically displaceable fashion.

6. The packaging machine according to claim 5, characterized in that each yoke rests on two spring elements (26).

7. The packaging machine according to claim 6, characterized in that one spring element (26) is mounted to one bar (15) each time.

8. The packaging machine according to claim 6 or 7, characterized in that the spring elements (26) are elastomeric springs.

9. The packaging machine according to any of claims 1 to 8, characterized in that driving is performed using an electric motor, preferably a servomotor, and preferably via a toothed belt.

10. The packaging machine according to claim 9, characterized in that the motor has a retention momentum of >10 Nm.

11. The packaging machine according to claim 9 or 10, characterized in that the motor can be rotated in two directions.

12. The packaging machine according to claim 11, characterized in that the crankshaft is rotated alternately in a clockwise and counterclockwise fashion by 180° at maximum.

13. The packaging machine according to claim 12, characterized in that the angle of rotation of the crankshaft is adjusted in such a way that the tool (4, 9, 11) is lowered by only such a level that the package trough is not damaged as it moves further on.

14. The packaging machine according to claim 13, characterized in that the top edge of the tool (4, 9, 11) during lowering is lowered by only 1-10 mm below the bottom edge of the package trough.

15. The packaging machine according to any of claims 1 to 14, characterized in that the lifting time is 1 second at maximum, preferably 0.5 seconds at maximum.

16. The packaging machine according to any of claims 1 to 12 and 15, characterized in that the spacing (25) corresponds to at least half the depth of the package trough (6).

17. The packaging machine according to any of claims 1 to 16, characterized in that the packaging machine includes a means to avoid squeezing of products between upper and lower tools.

18. The packaging machine according to claim 17, characterized in that the means comprises a limitation of the admissible consumption of power during the upward motion of the lower tool.