Conveyors: power-driven – With means to facilitate working – treating – or inspecting...
Reexamination Certificate
2000-11-10
2001-10-09
Ellis, Christopher P. (Department: 3651)
Conveyors: power-driven
With means to facilitate working, treating, or inspecting...
C198S345100
Reexamination Certificate
active
06298974
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a method and apparatus for rotating rotationally symmetrical containers, such as bottles, while transporting them on a conveying surface. The containers are transported under backup pressure and are guided during the transportation, for which the conveying surface has a guide device or a railing on each side.
In particular empty glass or plastic bottles are rotated about their axis for inspecting their side walls. A side wall inspection device is known from EP-A-O 415 154 with which the lateral guide devices consist of belts arranged on both sides of the conveying surface and driven at different speeds so that the empty bottles held between them are rotated about their longitudinal axis. That apparatus requires that the empty bottles have previously been separated or at least guided to the conveying surface free of backup pressure. Therefore, if the empty bottles are not arranged free of pressure, they must be separated.
The invention is based on the problem of enabling the rotation of containers conveyed under backup pressure about their longitudinal axis in a simple manner.
This problem is solved according to the method of the invention in that one of two consecutive containers is arranged offset stable to one side and the other stable to the other side seen in the direction of conveyance after the site at which the containers are to rotate.
The problem is solved within the scope of the apparatus of the invention in that a device is provided for the stable arrangement of one of at least two consecutive containers against the railing and the other container against the other railing in the direction of conveyance after the site at which the containers are to rotate.
Apparatuses are known from DE-C-843 973 and DE-C-922 519 for transporting empty bottles under backup pressure with which empty bottles are alternately offset to the left and to the right railing. However, with those apparatuses, disturbances that lead to a change in the position of a container from one railing to the other railing propagate from the exit end of the conveying device counter to the direction of transportation. Such a change in position then also leads to a reversal of the direction of rotation of the individual empty bottles so that a defined rotation of the empty bottles is not achievable.
According to the basic concept of the present invention, a stable arrangement of at least two containers at the left or, resp., right railing prevents such a disturbance and a change in the position of the individual containers caused by that from taking place after those containers.
All subsequent containers lie stable against one of the two railings and roll along the railing and against each other, the containers rolling alternately along the left and right railing with alternate direction of rotation.
An apparatus for transporting rotationally symmetrical containers is known from U.S. Pat. No. 2,725,138, the containers backing up at the end of the conveying surface and rolling along the side rails. At the end of the conveying surface, the containers are arranged at defined distances on a further transporting device by means of a star wheel. Upon being taken over by the star wheel, each container is pushed laterally against the same railing. Hence, the containers which were previously positioned at the other rail change their position. That change of position causes all subsequent containers likewise to change their position and therewith also their direction of rotation.
The conveying surface can be moving or fixed. Moving conveying surfaces are conveyer belts, chain link conveyers, air cushions, rollers and the like. Fixed conveying surfaces can be simple metal slideways on which the containers are pushed by means of backup pressure, the backup pressure can be produced by a star wheel or a seriesed chain link conveyer. In this context, the term “transporter” encompasses all these kinds of conveying surfaces.
SUMMARY OF THE INVENTION
In a first embodiment of the device for stabilizing the position of at least two consecutive containers, the distance between the two railings in the direction of conveyance is to begin with gradually broadened to about 1.5 times the diameter of the containers and then narrowed down at an angle of the two railings to each other of about 30 to 100°, preferably 50 to 80°, to somewhat more than the diameter of the containers. The path of the railings in this area preferably mirrors or is symmetrical to the midline of the transporter.
The distance between the two railings has an effect on the pressure conditions in the stream of the containers. The following relationships are applicable:
α
=
arc
sin
(
V
/
D
)
V
=
D
-
d
F
1
n
=
(
2
·
n
-
1
)
·
F
R
·
sin
α
cos
α
=
(
2
·
n
-
1
)
·
F
R
·
tan
α
F
2
n
=
n
·
F
R
cos
α
V=lateral displacement of consecutive containers;
D=distance between the lateral rails (width of the transporter);
d=diameter of the containers;
&agr;=angle between the connecting line of two consecutive containers and the direction of transportation;
F
1n
=the force of the nth container acting on the railing;
F
2n
=the force component acting on the subsequent container
F
R
=friction force between container and railing.
The apparatus works stable in a broad range of the backup pressure. However, in practice, extreme situations which can lead to disturbances in the rotation behavior of the container result due to most varied influences. Those influences can be allayed by additional measures so that a disturbance of the operation is largely prevented. Very strong pressure at the upstream end of the apparatus can be reduced by a mechanical resistance in the course of the transporter before the apparatus. For example, there can be arranged on the transporter a thin metal sheet over which the containers slide and thereby undergo an additional friction. Baffles which reduce the pressure peaks can also be built up by means of the side railings. The backup pressure is also reduced by the apparatus of the invention itself so that the backup pressure for a subsequent apparatus is reduced by a preceding apparatus. If, vice versa, too low a backup pressure exists, the container can be imparted a force acting in the direction of transportation by a laterally arranged belt running along with it.
By narrowing the distance between the railings at a relatively large angle, it is achieved that in the case that a container at the section of the transporter again narrowed down changes its position from one railing to the other, this does not have any influence on the position of the subsequent container still within the narrowing area. That is to say, the pressure point between the two containers shifts so slightly due to the narrow free movement area of the preceding container that the subsequent container is not forced to change its position to the other railing. The chaotic behavior of the containers is therewith interrupted and a clear and stable arrangement of the containers is attained.
In a second embodiment, the device for stabilizing the position of at least two consecutive containers is a star wheel that is arranged rotatable about a vertical axis adjacent to the transporter and has cutouts on its perimeter of alternately different depth that are distributed to correspond to about the diameter of the containers such that the teeth push every second container against the opposite railing while the intermediate containers rest against the adjacent railing due to the cutouts. Two such star wheels can also be arranged meshing on the left and right adjacent to the transporter, the containers then passing through between the two star wheels.
A stable arrangement of the containers is also possible alternately at the one and the other railing by means of a worm arranged adjacent to th
Goller Hans-Ulrich
Heuft Bernhard
Ellis Christopher P.
Gardner Carton & Douglas
Heuft Systemtechnik GmbH
Tran Khoi H.
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