Patent Application
20250033822
The present invention relates to a lifting means, in particular for a packaging machine, which has a frame and moves a lifting table from a lowered to a raised position and vice versa, comprising:
The present invention also relates to a packaging machine and to a method.
Generic lifting means of this kind are known from the prior art, for example EP 0 895 933 A1 or DE 10 2017 123 805 A1, and are used in particular in packaging machines. In these packaging machines, for example a lower material web is unrolled from a supply roll and intermittently conveyed along the packaging machine. In the thermoformer, a pack cavity is first formed into the lower material web in a forming station and then filled with a product to be packaged, in particular a foodstuff. The pack cavity is then closed with an upper material web, which is sealed onto the lower material, in a sealing station. This material web is also unrolled from a supply roll. The forming station and/or the sealing station generally have a lower tool and an upper tool, the lower tool being located below the lower material web and the upper tool being located above the upper material web. When the pack cavity is being formed into the lower material web and/or when an upper material web is being sealed onto the lower material web, the respective lower tool has to be raised, and during/before the onward conveyance of the pack cavities, said lower tool has to be lowered by an index again. In some cases, the upper tool also has to be raised and lowered, preferably in the opposite direction to, and synchronously with, the movement of the lower tool. For this purpose, the packaging machine has at least one lifting station, preferably a lifting station per tool.
There is therefore constantly the need to improve these lifting stations and/or to provide a packaging machine with an improved lifting means.
The object is achieved with a lifting means, in particular for a packaging machine, which has a frame and moves a lifting table from a lowered to a raised position and vice versa, comprising:
The statements made with regard to this subject of the present invention apply equally to the other subjects of the present invention and vice versa. Features disclosed in connection with this subject of the present invention can be combined with other subjects of the present invention and vice versa.
The present invention relates to a lifting means, by means of which in particular at least one tool of a forming station of a packaging machine, a sealing tool or cutting tool, is transferred from an open to a closed position and back. In the open position, two tools, for example upper tool and lower tool, have been spaced apart from one another, and in the closed position, they have been moved toward one another. In a packaging machine, for example a material web is located between the two tools. In a simplified embodiment, one of the two tools is positionally fixed, for example by virtue of the tool being arranged on the frame of the lifting means and/or on the frame of the assigned packaging machine.
According to the invention, this lifting means has a frame, which consists, for example, of two parallel plates. This frame can be arranged on the frame of a packaging machine, in particular displaceably along the longitudinal extent of the packaging machine. As an alternative, the frame of the packaging machine is also the frame of the lifting means.
Furthermore, according to the invention, the lifting means has two parallel shafts, of which preferably only one is rotatingly driven in a motorized manner, in particular by means of an electric motor, preferably with a servomotor. The shaft is preferably rotated through 180° during each movement. The output shaft of the motor is preferably connected directly, without a transmission, to the shaft.
As an alternative, the drive shaft of the motor is connected to the shaft for example by means of a hollow shaft transmission. Again as an alternative, the drive is arranged next to the shaft and connected to the shaft by means of a transmission, for example a toothed belt transmission or a lever drive, in particular a toggle lever drive, wherein the drive is located within the lifting means or alternatively outside the lifting means, for example if the lifting means is very compact and there is not enough space available within the lifting means for arrangement of the motor. In this case, the motor may be arranged in the plane spanned by the shafts or alternatively outside the plane, for example above it.
The lifting means according to the invention also has two toggle levers, wherein in each case a toggle lever is connected to a shaft. Each toggle lever has a first rotary lever and a second rotary lever, which are each rotatingly connected to one another at one of their ends. Each toggle lever is respectively provided between one of the two shafts and the lifting table, wherein a lever of the toggle lever is rotationally fixedly connected to one of the two shafts. The first lever may be provided, for example forged or cast, in one piece with the shaft or be connected thereto in a materially bonded, form-fitting and/or force-fitting manner. For example, the first lever is welded to the shaft. Preferably, the toggle lever moves the lifting table from a lower dead center position, in which the two tools are at a maximum spacing from one another, to an upper dead center position, in which the tools are at their minimum spacing from one another or are even touching, and back.
According to the invention, at least two coupling rods are now provided between the two shafts. These coupling rods each transmit the torque of the motor-driven shaft to the other shaft, with the result that these move synchronously. The at least two coupling rods for example ensure that the torques move the toggle levers out of at least one of the two dead center positions.
The coupling rods are preferably arranged parallel to one another and are very particularly preferably embodied to be at least substantially structurally identical.
Both coupling rods are preferably connected to the same first rotary lever on the respective shaft. Each first rotary lever of the toggle lever is preferably connected to both coupling rods.
Preferably, the two coupling rods are connected to the respective rotary lever at different angular positions and/or at different spacings to the axis of rotation of the rotary lever.
The two shafts have a longitudinal extent direction. Preferably, the two coupling rods are provided offset relative to one another in relation to this longitudinal extent direction, but particularly preferably are provided offset relative to one another only by the thickness of the lever.
Preferably, each first lever has two opposite, in particular identical surfaces spaced apart from one another by the thickness of the lever. Particularly preferably, one coupling rod is then arranged adjacent to the one surface and the other coupling rod is arranged adjacent to the other surface on the first lever of the toggle lever.
According to a preferred embodiment of the present invention, the coupling rods are each U-shaped, the base of the “U” preferably being longer than the limbs of the “U”. Preferably, the limbs are of different length, and very particularly preferably, at least one limb is not provided at a right angle with respect to the base. The ends of the limbs of the U-shaped coupling rod are preferably each rotatably connected to a first lever of the toggle lever.
Preferably, a respective end of the two coupling rods and the second rotary lever are connected to the same first rotary lever of the toggle lever, but particularly preferably at three different locations on the first rotary lever.
According to a preferred embodiment of the present invention, at least one rotary lever of the toggle lever, in particular the second rotary lever connected to the lifting table, is curved. Particularly preferably, this lever has a rectilinear portion and a U-shaped portion.
As an alternative, the lifting means has more than two parallel shafts, for example if the lifting means is used to drive longer or additional tools and/or if required for the load transfer. Those skilled in the art will understand that the number of toggle levers and coupling rods increases accordingly, wherein two additional toggle levers and coupling rods are used per additional shaft to be attached, wherein, as an alternative, the coupling rods present for two parallel shafts are extended/widened up to the additional shaft(s).
A further subject according to the invention, or preferred subject of the present invention, is a generic lifting means in which the first rotary lever of the toggle lever in each case rotates through 178°-182°, preferably exactly through 180°, during the movement between the lowered to the raised position and vice versa.
The statements made with regard to this subject of the present invention apply equally to the other subjects of the present invention and vice versa. Features disclosed in connection with this subject of the present invention can be combined with other subjects of the present invention and vice versa.
A further subject according to the invention, or preferred subject of the present invention, is a generic lifting means in which the second rotary lever has a first axis of rotation and a second axis of rotation and in which, in the raised position of the lifting table, these first and second axes of rotation are aligned with the axis of rotation of the shaft in a perpendicular.
The statements made with regard to this subject of the present invention apply equally to the other subjects of the present invention and vice versa. Features disclosed in connection with this subject of the present invention can be combined with other subjects of the present invention and vice versa.
This embodiment according to the invention, or preferred embodiment, has the advantage that the lifting means can take a very large load in the raised position. Only very small torques, if any, are transmitted to the shafts.
This embodiment according to the invention, or preferred embodiment, also has the advantage that customary manufacturing tolerances, which cannot be avoided in spite of all the manufacturing precision, in the coupling rods and/or in the levers connected thereto, in particular with respect to their bearing spacing dimensions (effective dimensions), can be utilized in the sense that, for example, a V-shaped position of the lower lifting means toggle levers relative to one another is set in the region of the top dead center OT, wherein preferably one lever is slightly before OT and one slightly after OT, wherein the process loads are preferably distributed uniformly among the coupling rods and/or levers and are compensated/mediated with respect to their action on the drive, that is to say that only a small process load, if any, acts on the drive or the sum of the process loads acting on the drive is minimized. Those skilled in the art will understand that in the case of zero tolerance, that is to say in the case of exactly the same effective dimensions, the toggle levers can theoretically be exactly at OT, which is preferred in particular when distributing load among synchronized shafts, but is possible only with great difficulty in the technical implementation.
Another subject according to the invention, or preferred subject of the present invention, is a lifting means in which each shaft is at least triply rotatably mounted.
The statements made with regard to this subject of the present invention apply equally to the other subjects of the present invention and vice versa. Features disclosed in connection with this subject of the present invention can be combined with other subjects of the present invention and vice versa.
This embodiment according to the invention, or preferred embodiment, has the advantage that the diameter of the shaft has to be smaller than in the case of a two-point mounting, although this embodiment according to the invention, or preferred embodiment, requires very high precision in the manufacture of the lifting means.
Another subject according to the invention, or preferred subject of the present invention, is a lifting means in which the outer periphery of the shaft is locally flattened for the fastening of a lever.
The statements made with regard to this subject of the present invention apply equally to the other subjects of the present invention and vice versa. Features disclosed in connection with this subject of the present invention can be combined with other subjects of the present invention and vice versa.
Preferably, both shafts have corresponding flattened portions. Particularly preferably, a rotary bearing for a lever is mounted on these flattened portions, the axis of rotation of said bearing running parallel to the axis of rotation of the respective shaft. Particularly preferably, these two axes of rotation are spaced apart from one another. A possible advantage of the flattening is the resultant possible minimization of the spacing between the two axes of rotation or the targeted realization of a desired spacing, which constitutes a measure for the vertical movement of the upper tool, the upper lifting means.
According to a preferred embodiment of the present invention, the upper tool, i.e. the tool located above the material web, is not rigidly connected to the frame of the packaging machine, but rather is variable in terms of its vertical position just like the tool. This is preferably realized by virtue of the above-described shafts of the lifting means not being positionally fixedly arranged on the frame, but rather being vertically displaceable relative to the frame. This allows the entire lifting construction, and thus also the upper tool, to be moved up and down.
Preferably, the two shafts are each mounted on the frame of the lifting means by means of at least one, preferably in each case two parallel rotary levers. Particularly preferably, in each case one end of the rotary lever is rotatably connected to the frame and one end of the rotary lever is rotatably connected to the first lever of the toggle lever. The rotation of this rotary lever moves the respective shaft vertically.
In particular, each rotary lever has a first axis of rotation and a second axis of rotation. In the raised end position of the respective shaft, and according to a preferred embodiment, these first and second axes of rotation of the rotary lever are aligned with the axis of rotation of the respective shaft along a perpendicular.
Preferably, the diameter of the shaft varies with the longitudinal extent thereof.
Preferably, the lifting means has at least one, preferably two, in particular four guide rods. The lifting table is moved along these guide rods. The upper tool is preferably provided at an end of the guide rods.
Preferably, the lifting table bears a tool, in particular the lower tool.
Another subject of the present invention is a packaging machine having at least one lifting means according to the invention, or preferred lifting means, as described above.
The statements made with regard to this subject of the present invention apply equally to the other subjects of the present invention and vice versa. Features disclosed in connection with this subject of the present invention can be combined with other subjects of the present invention and vice versa.
Preferably, the longitudinal extent direction of the shafts is arranged transversely with respect to the conveying direction of a material web.
Another subject of the present invention is a method for raising and lowering a lower tool and an upper tool of a packaging machine with a lifting means, which has a frame and moves a lower tool and an upper tool from a lowered to a raised position and vice versa, comprising:
The statements made with regard to this subject of the present invention apply equally to the other subjects of the present invention and vice versa. Features disclosed in connection with this subject of the present invention can be combined with other subjects of the present invention and vice versa.
This subject of the present invention relates to a method for raising and lowering a lower tool and an upper tool of a packaging machine with at least two shafts.
The lower tool is provided on a lifting table, with which two toggle levers engage. The toggle levers are preferably provided on different shafts. A lever of each toggle lever is rotationally fixedly connected to a respective shaft. Generally, the toggle levers are synchronized, in particular forcibly synchronized, with one another, for example by at least one coupling rod.
The upper tool is also connected directly or indirectly to two toggle levers, wherein a lever of each toggle lever is rotationally fixedly connected to a respective shaft. The toggle levers are preferably provided on different shafts. Generally, the toggle levers are synchronized, in particular forcibly synchronized, with one another, for example by at least one coupling rod.
The lever connected to the shaft may be identical for both toggle levers provided on a shaft.
At least one of the two shafts is driven. The shafts move the toggle levers, as a result of which the movement of the lifting table and a vertical displacement of the shafts is effected. The movement of the upper tool is not derived from the movement of the lower tool. Preferably, the upper tool is mounted on the shafts and is also moved vertically by the vertical movement thereof.
The shafts are not mounted on the framework of the packaging machine by means of an eccentric and/or are not moved vertically by an eccentric.
The inventions will be explained below on the basis of the figures. These explanations are merely exemplary and do not restrict the general concept of the invention. The explanations apply equally to all the subjects of the present invention.
The packaging machine according to the invention may also be what is known as a tray sealer, in which filled pack cavities are closed with a covering material.
If the upper tool 3, 12, for example the forming and/or sealing station, is also intended to be moved vertically, the shafts 25, 35 are mounted not positionally fixedly on the frame 31 but rather vertically displaceably. For this purpose, at least one, preferably two rotary levers 21 are provided per shaft. The one end of the rotary lever 21 is mounted on the frame 31 by means of a rotary bearing. The other end of the rotary lever 21 is rotatably provided on the shaft, in particular on a lever, particularly preferably on the first lever 13 of the toggle lever. If the shaft 25, 35 rotates, it is raised or lowered. The shaft 25, 35 is connected to the upper tool 3, 12 which, as a result, is also raised or lowered.
The lifting means according to the invention preferably has at least one, particularly preferably multiple and very particularly preferably all of the following special structural features:
It can also be gathered from the illustration according to
The functioning of the lifting means is explained again below. If a shaft rotates, for example the shaft 25, the first rotary lever 13 rotationally fixedly provided on it is also rotated. The second lever 21 and the second lever 20 are rotatably arranged on this lever 13. The levers 13, 21 and 13, 20 form a respective toggle lever, which is driven in each case by a shaft, here the shaft 25. The toggle lever 13, 20 moves the lifting table 5, and thus the lower tool, up and down during a rotation of the shaft 25. The toggle lever 13, 21 is provided between the shaft 25, 35 and the frame 31 of the lifting means and displaces the shaft 25 vertically. Those skilled in the art will understand that the two toggle levers 13, 20 and 13, 21 do not have to have a common first lever 13, rather each toggle lever can have its own first lever, which are then preferably provided axially offset relative to one another on the shaft 25. The shaft 25 is rotatably mounted in a base 40 (illustrated in dashed lines) which is also moved vertically by the vertical movement of the shaft 25. The upper tool 3, 12 is mounted on the base 40 and also performs the movement thereof.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2021 214 892.1 | Dec 2021 | DE | national |
This application is a US National Stage entry of PCT/EP2022/086588 filed on Dec. 19, 2022, which claims priority to DE 10 2021 214 892.1 filed on Dec. 22, 2021, all of which are hereby incorporated by reference herein for all purposes.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2022/086588 | 12/19/2022 | WO |
