This application claims priority to European Patent Application No. 20174623.7, filed May 14, 2020 and entitled “Device for transporting ready-cut and filled pieces of tube”, which is hereby incorporated by reference herein in its entirety for all purposes.
The present invention relates to a device for transporting ready-cut and filled pieces of tube within a machine for producing double-chamber bags filled with tea.
The device, known from DE 38 06 386 C1, has a transport wheel carrying a plurality of double-chamber forming sets distributed on the circumference. Each double-chamber bag forming set comprises a profile part supporting the bottom of the double-chamber bag to be formed and comprises arms provided on both sides for this purpose. In the prior art, when forming the double-chamber bags, previously separated pieces of tube, each containing two portions of tea, are clamped between the arms and a concave contact surface of a cover. These two arms are moved toward each other while a profile part located between the arms holds and guides radially inwardly a central portion of the separated piece of tube. The result of this is a substantially W-shaped configuration of the double-chamber bag, with the two tea portions contained in opposite chambers of the double-chamber bag.
According to the prior art described above, the actuation and mounting of the respective arms is effected via a toggle mechanism, the levers of which are partially swivelably mounted on the transport wheel. There are provided two arms and the movable profile part provided between them for each double-chamber bag forming set of the rotating transport wheel. The arm at the front in the direction of rotation is referred to below as the leading arm, while the arm of the double-chamber bag forming set behind in the direction of rotation is referred to as the trailing arm. The profile part is located between the leading and trailing arms.
DE 195 32 816 B4 also does not deviate from this basic design and merely develops the aforementioned state of the art further in that the arms are designed as elastic springs, so that the separated piece of tube is elastically biased against the contact surface of the cover.
The actuation and mounting of the arms via a toggle mechanism is complex. It requires a considerable number of components, but nevertheless permits kinematics of the arms together with the profile part in such a way that the formed double-chamber bag can be swivelled with respect to a strictly radial direction in order to position a bag head for subsequent stapling on the transport wheel such that it extends substantially tangentially to the transport wheel.
It is an object of the present invention to constructively simplify the aforementioned device.
To solve this object, the present invention proposes a device having the features of claim 1. In this device, the arms are swivelably mounted eccentrically to the axis of rotation of the transport wheel. Thereby, all arms usually lie on a circular surface, which is arranged concentrically to the axis of rotation of the transport wheel. But even more, the arms of adjacent double-chamber bag forming sets are swivelably mounted on a common axis.
Thus, the trailing arm of a double-chamber forming set that is in front in the direction of rotation is mounted on a common axis with the leading arm of the adjacent double-chamber bag forming set that, in the direction of rotation of the transport wheel, is arranged behind or upstream. If, for example, eight different stations are formed by the transport wheel, each with a double-chamber forming set, then only eight swivel axes need to be formed on the transport wheel itself, each of which allows two of the arms to be swivelled. This significantly reduces the design effort required to manufacture the device.
For further simplification of the design of the apparatus according to the invention, it is proposed in accordance with a preferred embodiment that one of the two arms of one of the double-chamber bag forming sets is driven in a swivelling manner via a cam track, while the other arm of this double-chamber forming set is driven in a swivelling manner in a forcedly coupled manner via a toothing with the one of the arms. In this way, only one of the two arms has to be driven, whereas the other arm, induced by the cam track and due to the toothing, is forced to swivel as a result of the swivelling movement of the one arm.
According to a preferred embodiment of the present invention, one of the two arms of one of the double-chamber forming sets is rotationally fixedly connected to a hollow shaft, in which a drive shaft of the arm of the adjacent double-chamber bag forming set is accommodated. This is based on the consideration that the transport wheel has a certain axial extension and basically accommodates within itself, between two circular discs, the components for supporting and driving the individual double-chamber bag forming sets. Thus, one of the shafts can extend between the two disks and be I swivelably mounted or supported at least on one side, preferably on two sides. The other of the co-axially provided shafts according to the further embodiment can make use of this bearing or support of the one shaft, for example, in that the other shaft is directly supported on the one shaft and is only indirectly supported on the transport wheel via the one shaft.
According to a further preferred embodiment of the present invention, a concave contact surface of the cover is arranged eccentrically to the axis of rotation of the transport wheel, the radial distance of this concave contact surface from the axis of rotation of the transport wheel being greater in a front region of the concave contact surface than in a rear region of the concave contact surface. The front area is the area that is first swept by the leading arm when the respective double-chamber bag forming sets are inserted. The rear section is upstream or behind with respect to the direction of rotation of the transport wheel. The arms can in principle make use of the embodiment according to DE 195 32 816 B4 and accordingly rest under a certain elasticity against the concave contact surface of the cover. The previously discussed embodiment has the effect that, by reducing the radius with increasing movement of the arms under the cover, the swivelling movement of the leading arm towards the center of the double-chamber bag forming set is supported by friction. With increasing rotation of the respective double-chamber bag forming set under the contact surface, the decreasing radial distance accordingly promotes the closing of the double-chamber bag forming set. This allows the swivel drive to the two arms to be provided overall as a weaker configuration. The embodiment can also be essential to the invention in itself. In this context, the invention is defined by the preamble of claim 1 and the features of claim 4.
The front portion of the concave contact surface is the portion, against which the arms abut for clamping the separated piece of tube, while the profile part is lowered in the direction of the axis of rotation of the transport wheel for forming the double-chamber bag. In other words, the front and rear portions according to this embodiment each form clamping surfaces that cooperate with the respective arms upon forming the double-chamber bag by closing the arms of a double-chamber bag forming set. In this case, the front portion is not a conical inlet portion intended to facilitate insertion of the separated piece of tube under the cover.
In other words, a radius in the direction of rotation of the transport wheel immediately in front of an engagement portion of a hold-down device, which forces the severed piece of tube towards the profile part and usually clamps it there, is larger than a radius in the direction of rotation behind this engagement portion.
Further details and advantages of the present invention will be apparent from the following description of an example of an embodiment in conjunction with the drawing. In the drawing:
In
The arms 6, 8 have plates 16, 18 at their ends, which correspond essentially to the design according to DE 195 32 816 B4.
The profile part 10 is arranged between the leading and trailing arms 6, 8 of a forming set 4 and is mounted on a guide rail 20 so as to be translationally movable. Three lever arms engage on the profile part 10, of which the lever arms 22, 24 are shown in
As can be seen from
As shown in
Apart from these details, the embodiment corresponds essentially to the embodiment described in DE 195 32 816 B4 or DE 38 06 386 C1.
In the embodiment shown, the concave contact surface 50 is arranged eccentrically to the axis of rotation 12 of the transport wheel 2. A radius indicated by reference sign R1 at the front end of the concave contact surface 50, i.e. at the transition between the inlet ramp 52 and the contact surface 50, is greater than a radius R2 at the rear end of the contact surface 50.
The mode of operation of the embodiment is explained below with reference to
In
Hereby, the arms 6, 8 of the leading forming set 4.1 have already left the contact surface 50 between
The eccentric mounting of the contact surface 50 and the reduction of the radius in the direction of the rear portion of the contact surface 50 in any case promotes the swivelling movement of the leading arm 8 in the direction of the profile part 10.
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