Background of the Invention
I. Field of the Invention
The present invention relates to an apparatus for stamping flat objects of different sizes and thicknesses, particularly postal items, which are arranged in a vertical or approximately vertical manner on a feed table, are singly removed therefrom, successively moved past a stamp and are conveyed to a depositing table. The fed and deposited objects are arranged in planes parallel to one another and the feed and depositing tables are successively arranged in a direction perpendicular to said planes. The objects are removed from the feed table at right angles to said direction and are supplied to the depositing table.
II. Description of the Prior Art
In such a known apparatus, the objects are stacked on the feed table in such a way that their rear edges, which are in the conveying direction during singling, engage against a common stop. During singling, the objects are then removed vertically upwards. As such apparatuses are normally used for stamping postal items, particularly letters, which can have widely varying sizes and weight, they suffer from the following disadvantages.
The singling device must be able to act over a considerable length compared with the objects to be singled, because the leading edges of the objects can vary widely between individual objects. Errors can also occur during singling, because the singling device can simultaneously take up and convey away several objects. Complicated measures are required for preventing this disadvantageous action. In addition, during singling considerable forces have to be applied, because the objects have to be raised. This force must be based on the maximum possible weight, although the weight of most objects is much lower.
Summary of the Invention
The present invention provides an apparatus with which singling can be carried out more reliably and in which the singling device has a more simple construction than in the case of known devices. In particular, its size is reduced and the force acting on the objects to be singled is less.
In the present invention stamping flat objects of different sizes and thicknesses described hereinbefore is accomplished by the objects being placed on the feed table with their leading edges in alignment in the conveying direction during individual removal and the conveying path thereof between the feed table and the depositing table being horizontal.
Brief Description of the Drawing
The invention is described in greater detail hereinafter relative to an embodiment shown in the drawing, which illustrates an apparatus for stamping flat objects, particularly postal items, of different sizes and thicknesses in plan view.
Description of the Preferred Embodiment
Referring to the drawing, there is illustrated an example of the present invention in the form of a feed table 2 on which the objects 1 to be stamped are stacked. The objects 1 are vertically arranged and one edge engages with a registering or locating stop 3. The objects 1 are located on a feed conveyor belt 4 and are kept in their vertical position by a feed stacking plate 5. Stacking plate 5 is fixed to an articulation 6, which is displaceable on the locating stop 3. The feed stacking plate 5 rests under its own weight on conveyor belt 4 and is always pressed by the latter against the objects 1 located on feed table 2. Conveyor belt 4 is movable in the direction indicated by the arrow. The movement of conveyor belt 4 is controlled by a switch (not shown) which is located in the vicinity of a pneumatic separating device 7 and determines the contact of the objects 1 with the separating device 7.
Separating device 7 has a revolving perforated belt 8 which exerts a vacuum on the furthest forward object of the stacked objects 1. Perforated belt 8 revolves clockwise and thereby moves with it the sucked-on, furthest forward object 1. A pneumatic backstop 9 facing perforated belt 8 contains the second object arranged behind the first object in the case where it happens to be carried along by the first object as a result of friction. Back-stop 9 also operates under vacuum, but this is lower than the vacuum acting through perforated belts 8 on the first object.
The objects 1 singled in the aforementioned manner are passed into the gap between two revolving conveyor belts 10 and 11 and are moved between them in the direction of the arrow.
The speed of conveyor belts 10 and 11 is higher than that of the perforated belt 8. As a result, the objects 1 guided between conveyor belts 10 and 11 are moved away more rapidly than the following objects supplied by the perforated belt. This leads to a gap being formed between the individual objects, which is adequate in order to be able to detect them individually.
The singled objects conveyed between conveyor belts 10 and 11 are detected by a light barrier 12. On detecting the leading edge of an object, this releases a revolution of a stamp 13 following in the conveying path of the objects. The stamp is replaceably fixed to a core-toothed stamp shaft. A further light barrier 14 is used for positioning the stamp 13 in the basic position between two stamping processes.
The object 1 released by conveyor belts 10 and 11 is supplied to the gap between stamp 13 and a back pressure roller 15. The resiliently mounted, driven back pressure roller 15 ensures strong, uniform stamp impressions. It is possible to preset the gap between stamps 13 and back pressure roller 15 by means of an adjusting device 16. This is advantageous when stamping approximately equally thick objects 1. This makes it possible to prevent continuous, percussive movements of the back pressure roller 15.
Back pressure roller 15 is also connected via an articulation 17 with a movably mounted pulley 18 which is used for guiding conveyor belt 10 and is arranged at the outlet of the slot formed by conveyor belts 10 and 11. As a result of this articulated connection between pulley 18 and back pressure roller 15, the latter is preset to the thickness of an object before the latter reaches stamp 13. Thus, uniform stamp impressions are still obtained, even in the case of varyingly thick objects.
An inking mechanism 19 with a filtered cylinder impregnated with the stamp ink and a driven intermediate roller is used for the uniform inking of stamp 13 during each revolution thereof.
After passing stamp 13, the objects 1 are taken up by a further conveyor belt 20 and are fed to a depositing table 21. This transfer additionally takes place with the aid of a guide plate 22 with a guide roller and supporting roller 23 with driving plate.
Depositing table 21 has substantially the same construction as feed table 2. The entering objects are initially separated from conveyor belt 20 by a stop bracket with stripper 24. The stacked objects are conveyed in the direction of the arrow by a depositing conveyor belt 25. A depositing stacking plate 26 displaceable in the same way as stacking plate 5 is pressed by a counterweight against the stacked objects 1, so that said objects are kept in their vertical position. They can be manually removed from the depositing table, whereby stacking plate 26 is then automatically moved toward the stripper 24 until it meets the newly deposited objects.
Through the leading edges of the objects 1 engaging with the locating stop 3, it is ensured that in each case only the furthest forward object comes into contact with the perforated belt 8 of the pneumatic separating device 7, so that reliable singling is made possible. Due to the fact that the objects are only moved horizontally from separating device 7 to conveyor belts 10 and 11, the suction force acting on the objects can be kept relatively small.