Patent Application
20180297733
The present invention relates to a device for emptying moist powder from a container, which device comprises a breaking ring, which is provided with one or more outwardly directed breaking ribs, a cross-shaped stabilizing structure and a breaking spike. The invention also relates to a method for emptying moist powder from a container by using the device.
Containers containing moist powder mixtures are used for charging weigh feeders. Because of the consistency of the mixtures, caked-on deposits form on the walls of the container and product bridges form at the outlet of the container, so that continuous operation without manual interventions is not possible.
There are three known method variants for emptying containers, which however do not work satisfactorily with moist powder mixtures.
According to the first method variant, the container wall is set in vibration by attaching a driven vibratory agitator to the outer walls of the powder-filled container. The vibrations are intended to have the effect that caked-on deposits of product are dislodged and run off into the weigh feeder.
According to the second known method variant, a container with a rubber discharge that is flexed with a driven pushrod is used. In this way it is intended to ensure an unproblematic run-off of product into the weigh feeder.
Thirdly, very steep container walls may be used. However, this merely creates a tubular run-out, i.e. the product flow in the container is at most equal to the diameter of the discharge tubing, and there is no slipping down of the product as it feeds through.
It has been found that caked-on deposits of moist powder mixtures on the wall of the container and the product bridge in the outlet cannot be dislodged with the aid of the three method variants of the existing prior art.
There are still further methods for the removal of bulk material from containers, which however do not represent the closest prior art. In the case of these methods, the removal takes place at the upper side of the container, that is to say at the surface of the bulk material. One method given by way of example is described in WO 2012/084734 A1. The removal in this case takes place by a suction device. By contrast with the methods described here, methods with a suction device involve a greater expenditure in terms of cost, have a greater tendency to need maintenance and demand a greater complexity of the equipment required, to be specific the suction device.
Therefore, in spite of the use of a vibratory agitator according to the first method variant, manual intervention at periodic intervals is always necessary in order for containers containing moist powder mixtures to be emptied completely.
Proceeding from the prior art described, the object was therefore that of providing a method and a corresponding device that allow containers to be emptied of moist powder as completely as possible without manual interventions being required. In particular, the method and the device are intended to be suitable for dislodging caked-on powder deposits on the walls of the container and at the outlet.
This object has been achieved by the subject matter of the patent claims.
It has surprisingly been found that a device comprising a breaking ring, which is provided with one or more outwardly directed breaking ribs and a cross-shaped stabilizing structure with a breaking spike is suitable for completely emptying moist powder from a container. It has been found that, by using the emptying device, caked-on deposits of product on the walls of the container can be avoided or dislodged and product bridges at the outlet can be broken. In this way, continuous operation of the weigh feeders without manual interventions can be ensured.
The subject matter of the invention is consequently a device (1) for emptying powder with a liquid content of at least 0.1% by weight from a container (2), characterized in that it comprises a breaking ring (3), which is provided with one or more outwardly directed breaking ribs (4) and a cross-shaped stabilizing structure (5) with a breaking spike (6).
A “powder” is understood for the purposes of the invention as meaning a component or a mixture of a number of components that are in a fixed state of aggregation and in the case of which the particles have particle sizes of less than 2 mm, preferably less than 1 mm, in particular less than 0.5 mm. Particularly preferred are powdered polymer compositions containing one or more thermoplastic polymers and optionally one or more additives and/or fillers.
According to the invention, the powder has a liquid content of at least 0.1% by weight.
In a preferred embodiment of the device according to the invention, the powder has a water content of at least 0.1% by weight. The determination of the water content may take place by Karl Fischer titration.
According to the invention, the device (1) comprises a breaking ring (3), which is provided with one or more outwardly directed breaking ribs (4) and a cross-shaped stabilizing structure (5) with a breaking spike (6).
The device may have a cylindrical or polygonal form; a cylindrical form is particularly preferred. The breaking ring (3) may likewise have an annular or polygonal form; it is preferably annular.
According to the invention, the device is provided with any desired number of breaking ribs (4); particularly preferred are 1 to 20 breaking ribs, most particularly preferably 3 to 16 breaking ribs. The breaking ribs are fastened to the outer edge of the breaking ring (3) and point outward. The breaking ribs may in each case point straight out in a radial direction or be curved. The distances between the breaking ribs may be the same or different. They are preferably approximately the same. The breaking ribs may have the same or different lengths. Preferably, the breaking ring is constructed with the breaking ribs axially symmetrical, and with preference has at least three axes of symmetry, preferably four axes of symmetry.
The breaking ring (3) also has in its interior a cross-shaped stabilizing structure (5), which connects a number of locations of the inner side of the breaking ring, preferably at least three, to one another and thereby imparts increased stability to the breaking ring.
The cross-shaped stabilizing structure (5) has according to the invention a breaking spike (6), which protrudes in the axial direction from the plane of the breaking ring. The breaking spike is preferably in the form of a rod and may have a circular or polygonal cross section. The breaking spike is preferably solid.
In a preferred embodiment, the device is also provided with a force transmission means (7), by way of which the device can be made to enter a container without manual assistance. Both fluid drives (hydraulic or pneumatic) and electric drives are suitable as types of drive for the force transmission means.
The device according to the invention is suitable for completely emptying moist powder from a container.
A further subject matter of the invention is therefore the use of the device (1) for emptying powder with a liquid content of at least 0.1% by weight from a container.
The container is preferably cylindrical and is preferably provided with a conical run-out. The container preferably has at the lower end an emptying fitting, for example an emptying nozzle, and also at the upper end a cylindrical opening. For emptying a moist powder from a container, the device must first be introduced into the container. As this happens, the breaking ribs and the breaking spike of the device serve for breaking up and dislodging caked-on powder deposits in the container.
For this purpose, first the container is opened and the device is attached to the opening of the filled container and the emptying fitting at the lower end of the container is opened. In this case, the device is attached to the container opening in such a way that the device is positioned centrally in the opening of the container and the lifting and lowering movement of the device centrally through the container is not impaired. Preferably used for this purpose is a rail or plate on which the device, to be more precise the force transmission means (7), is fastened. Subsequently, the device is made to enter the container with the aid of a force transmission means (7) attached to the cross-shaped stabilizing structure (5). As this happens, the powder bridge is broken open by means of the breaking spike (6) and caked-on powder deposits are dislodged with the aid of the breaking ribs and the breaking spike.
In a next step, the device is moved up and, by alternately moving the device down and up repeatedly, further caked-on powder deposits are dislodged until the container has been emptied.
A further subject matter of the invention is consequently a method for emptying powder with a liquid content of at least 0.1% by weight from a container (2) comprising the steps of:
Features of the device according to the invention are illustrated in
| Number | Date | Country | Kind |
|---|---|---|---|
| 15199612.1 | Dec 2015 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2016/079843 | 12/6/2016 | WO | 00 |
