Conveyors: power-driven – Conveyor arrangement for selecting among plural sources or... – By loading or unloading section at selected one of a...
Reexamination Certificate
1999-12-29
2001-11-13
Valenza, Joseph E. (Department: 3651)
Conveyors: power-driven
Conveyor arrangement for selecting among plural sources or...
By loading or unloading section at selected one of a...
C198S370080, C198S812000, C198S792000, C198S794000
Reexamination Certificate
active
06315101
ABSTRACT:
The invention concerns a chain conveyor, for example for a machine for sorting flat objects, and a machine for equipping a logistic platform, such as a mail sorting centre and similar.
In the logistics field, such object sorting machines are known.
The objects conveyed and sorted by the means of the machine must be conveyed to a given destination, and are collected in sorting containers.
In this field can be cited the document FR-97.16.590 which describes a logistic installation machine where a transporter of full containers is moved in front of unloading stations parallel to a conveyor of empty containers.
It is necessary to place the containers, completely individually, under the fixed automatic filling stations, disposed in a straight line.
It is also necessary to remove these containers when they are full of sorted objects.
In this document, a transporter of empty containers is placed along and next to the filling stations.
A removal conveyor is placed along and on the other side of the stations. Each pendular transfer provides a horizontal thrust to the rear of an empty container which comes into contact with the full one.
At the end of the transfer, the empty container is situated in the place of the full one, under the filling, and the full one has been transferred on to the removal conveyor.
This transfer device comprises a pendular lever controlled by a connecting rod driven rotationally by a motorization unit.
The kinematic connection between the connecting rod and the lever is a sliding connection, having the advantage of a movement with no reversal of the direction of rotation of a motorization unit.
Although generally giving satisfaction, notably as regards the transfer device, the known logistic machines have drawbacks.
To illustrate these drawbacks, reference is made to the sorting machine mentioned.
But the invention obviously applies to other objects to be conveyed in the form of revolving stock, as to containers having to be filled with letters.
Thus the conveyors, often disposed laterally towards the outside of the machine, are provided so that the empty containers are moved forward step by step, with disengageable regions.
In practice, these conveyors cannot allow a precise stopping position (of the order of a few mm, for example 5 mm) for the containers, opposite their corresponding stations, short of providing limit stops at each location.
This solution is not economically acceptable, and requires a sometimes excessive size to be managed.
Furthermore, there is often created, as the empty containers are transferred upstream away from the feed conveyor, a dispersal downstream, along useful sections of such conveyors, that is to say along the transfer sections opposite the unloading stations.
This dispersal appears in the form of significant distances which are formed at the time of transferring containers upstream, between two successive containers on the conveyor.
There are then no more empty containers available in the downstream part of the unloading zone.
Furthermore, the known conveyors do not allow an easy solution to the problem of the transportation of containers inclined in the direction of their movement.
Such inclining is frequently desirable inasmuch as it itself provides a precise positioning, oriented along the three geometric axes of the container with respect to the filling bucket conveyor.
The invention aims to overcome these drawbacks notably by providing a central revolving stock of objects to be transferred, available continuously, for example inside a logistic machine.
The continuous availability of objects means that it must allow an endless supply of these objects to and/or from the machine.
According to one embodiment, the invention aims to provide a conveyor providing a precise positioning of the objects at both input and output of the revolving stock.
The input objects must notably be aligned in a precise position in front of the output objects, and vice versa.
On account of the notion of a compartmentalized conveyor, each tray of which is addressed in order to provide parity between the object and its compartment, the invention also has the aim of allowing a high rate of loading/unloading of the objects in the revolving stock from and/or to the logistic machine.
By way of example, some machines provide several hundred loading/unloading stations, and require a rate of the order of one object loaded/unloaded every 4 or 5 seconds.
To that end, a first object of the invention is a closed-loop chain conveyor of three-dimensional objects, for example for a machine for sorting flat objects.
The chain has stretches with links comprising respectively, or each, object receiving means, these links being:
self-conveyed on a track possibly devoid of directional guides,
mutually connected by articulations with small positive operating and wear tolerances,
guided separately from the conveyance, in a guide rail, and
of fixed pitch, substantially equal to the distance separating two adjacent object loading/unloading positions, these links being referred to as fixed-length links.
At least two adjacent stretches are connected by a so-called “tensioning” variable-pitch link, of structure similar to that of a fixed link, except in that it has tensioning means capable of automatically adjusting the distance between its axes of articulation with two adjacent links, by continuously exerting a tension force tending to bring these axes closer together, the power of which is determined in order to be greater than a maximum motorization power of the chain.
The conveyor has means of detecting the position of a fixed or variable link, with respect to a reference location where the object has to be loaded/unloaded, connected to a motorization of the conveyor for allowing a uniformly varying and smooth slowing down of the chain at the approach to this location, then of stopping the chain at a reduced conveying speed in a precise position facing this location.
The guide rail has at least two curved sections and two rectilinear sections, each curved section having adjustment devices making it possible to move this curve individually, arranged to provide a tensioning of the chain, as well as a relative adjustment of the locating of the straight sections with respect to one another, as soon as the chain is immobilized by the motorization, which also serves as a brake.
Thus, slackening of the chain in one of the curved sections is compensated for by an excess tension in the other, and vice versa.
In another embodiment, instead of the two adjacent stretches connected by a variable-pitch link which has means providing a permanent internal residual tension, these two stretches are connected by an adjustable link which allows play to be taken up without tension.
For example, this embodiment provides a link which has sliding means of connecting its two parts, for adjusting the length of the chain, and means of immobilization at an appropriate pitch, here clamping screws.
It is self-evident that some embodiments have at least one such tensioning link, or at least one link for taking up play, while other embodiments have these two types of link.
Similarly, other embodiments can have only fixed-pitch links.
The stretches with fixed, variable and/or adjustable links, make it possible to concentrate all the tolerances accumulated on one stretch at the connecting links between stretches, and not on each link or articulation, which is more complex.
The overall tolerance on the whole of the chain is therefore equal to the product of the travel available at each variable and/or adjustable link, and the number of stretches in the chain.
Thus, the effective positional error of a particular link is statistically much less than this overall tolerance.
In this way, it can be achieved that the overall positioning error tolerance of a stretch is easily made less than the precision required for the object loading/unloading position.
It should also be noted that, for the tensioning type variable-pitch links, the pitch distance after tensioning of the chain is made substantially equal to a
Deuble Mark A.
Gallet Systemes Automatises
Nawrocki, Rooney & Sivertson P.A.
Valenza Joseph E.
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