MXPA99007409A - Po measurement apparatus - Google Patents

Abstract

The present invention relates to apparatus for measuring powder that delivers a powder-air mixture to a consumer, comprising: a metering pump including a rotating driven metering disk mounted between and immediately adjacent to each of two side plates; The meter has measuring chambers distributed on its circumference, an entrance through which a mixture of dust-air is supplied in series to the measuring chambers of the rotating measuring disk and an output from which the powder-air mixture removed in series of the measuring chambers of the rotary measuring disk, an injection pump connected to the outlet of the metering pump through a rejection pipe to generate a suction in the suction pipe that serves to generate a vacuum flow that removes the mixture in series Dust-air measurement of the rotary meter disk measuring chamber and supply the powder-air mixture to a consumer, and a controller through which the bo mba of injector can be controlled in a way with regulated pressure as a function of the rotational speed of the measuring disk of the measured pump

Description

POWDER MEASURING DEVICE DESCRIPTION OF THE INVENTION The invention relates to a dust measuring apparatus for powder coating. EP 0 412 289 Bl discloses an electrostatic powder coating device, wherein an injection pump supplies powder for coating by means of a trant gas, and wherein an additional measured gas line from a source of compressed air connects the pump injector. The measured gas line, by means of which the measured gas is supplied to the injection pump, is intended to easily adjust the amount of air tranted and the amount of air measured to the optimum valves. While the introduction of gas measured in the injection pump improves the cont rolibility of an injector pump with respect to the supply of a desired amount of powder necessary in particular to coat, cont rolab lity and thus measure the capacity of the amount of dust without, however, achieving the accuracy of the pumps to request rotationally controlled, conventional, disc-type drives.

DE 4 242 225 A 1 describes a powder coating pump for producing and measuring a powder, which flows under overpressure. In the described powder coating pump, the current feed pump is designed and constructed as a disk type metering pump. In this pump, a measuring disk is arranged for rotation between the lateral components. The measuring disk has an inlet, which receives a mixture of dust air, and an outlet, which supplies the powder air mixture to a consumer, i.e., the coating purpose described. The discharge of the powder air mixture from the outlet of the metering pump occurs by means of compressed air. As a result of the compressed air it is possible for dust deposits inside the outlet chamber and in part at the sealed points between the rotary measuring disk and the stationary lateral components. The dust deposit in the areas described increases the wear of the metering pump. In addition, the metering pump has an increased torsional force which can be directed to an obstruction of the metering pump. Likewise, there is a risk of escape.

It is therefore the object of the invention to provide a powder measuring apparatus with a metering pump known per se, which accurately measures the amount of powder needed for the coating, operates with little wear and reliability, and where the powder it largely prevents it from being deposited in particular in its sealable cavities. This object is to achieve by means of a powder measuring apparatus having the characteristic features of claim 1. Further developments are defined in the dependent claims. Accordingly, a powder measuring device comprises a "metering pump with a measuring disk arranged between side plates." The measuring disk connected to a shaft that mounts a mechanism, which rotates the measuring disk between the side plates. The measuring disk contains 'reception or reception chambers or measuring chambers' openings, which receive an air-powder mixture for the measuring pump via an inlet. By rotating the measuring disk, the mixture is "tranted to an outlet from which the powder or" air-powder mixture in the openings or chambers of the measuring disk are discharged. In addition, the powder measuring apparatus comprises an injection pump. The output of the measuring pump connects to the injection pump by means of a suction tube. A vacuum flow generated in the injector pump and entering the metering pump by means of a suction inlet end is used to suck the powder or powder air mixture out of the outlet or the outlet chamber of the suction inlet. the measuring pump and to supply it accordingly to a consumer. As a result of the combination of a metering pump of the disc type known per se, which measures with great accuracy, but is subject to a relatively large wear due to the possibility of depositing the powder in the sealed cavity, and an injection pump whose supply is adjustable with only a relatively small accuracy, and whose r ep r Due to numerous factors, such as grain size, torrential density, formation of the fluid bed in the powder feed device, etc., it is possible in this way to achieve a simple adjustment, reproducible of the supply. The important variables that influence the supply, is the rotational speed of the measuring pump, the size of the chamber, and the torrential density. The fact that the vacuum flow means, dust or air-powder mixture are sucked out of the outlet chamber of the metering pump to the application device prevents the powder from depositing in the sealable cavity between the disk measurement and the lateral contour discs of the measuring discs. This reduces the wear of the measuring pump considerably. According to a preferred embodiment of the invention, the injection pump comprises a first control element for controlling the vacuum flow. By means of this first control element the vacuum flow is controlled in such a way that it prevents the dust from depositing in the outlet and / or between the measuring disk and the side plates. The magnitude of the vacuum flow, that is, the flow velocity prevailing in the injector suction tube, which depends, among other things, on the geometrical dimensions of the injection pump and the suction air flow, which is used to generate- the vacuum flow in the injector suction tube.

Preferably, a controller is also provided, which facilitates control of the injection pump in the form of regulated pressure as a function of the rotational speed of the metering pump.This has the advantage that the metering pump and the injection pump can to be optimally adapted to each one with respect to supply, accuracy, and reliable operation with little wear. According to a further embodiment, the first control element of the powder measuring device is arranged upstream of the end of the suction inlet of the measuring pump. This first control element causes a controlled airflow from a compression air source to the inlet of the suction inlet end in an auxiliary flow form. Preferably, to assist the transmission action of the injection pump downstream of the injection pump, a second control element is provided, which causes an additional air stream to be introduced in a controllable form. The additional air flow is used to aid in the determining influence of the suction air flow of the injection pump and, thus, the vacuum flow with respect to the flow velocity. Preferably a third control element is provided to control the air flow supplied to the injection pump. The provision of the respective control elements in this way makes it possible to adapt and adjust the flow conditions and thus the operation of the metering pump as well as the amount of discharged powder determinant and optimally to the respective cases of the application. According to a further development of the powder measuring apparatus of the present invention, the first, second and third control elements are controlled by means of a controller. Preferably, the air-powder mixture is generated in a fluid bed in a reactor of a powder measuring device which is connected to the inlet of the metering pump. Preferably, the fluid bed is maintained even along a feed channel connecting the container to the inlet of the metering pump. This ensures uniform filling of the measuring pump. The feeding device consists of a container and a feeding channel. Both of the containers and the feed channel comprise a fluid bed, in which a stream of air flows into the filled powder in the container and thus converts the powder into an air-powder mixture. This air-powder mixture is necessary in such a way that the powder is able to flow uniformly. According to a further development, at least the side plates of the measuring pump comprise hollow spaces for the flow of a coolant. This ensures that the powder is not overheated inside the pump. The further advantages, features and possible applications of the invention are now described in greater detail with reference to the embodiments shown in the accompanying drawings, in which: Figure 1 illustrates a first embodiment of a powder measuring apparatus of the present invention; Figure 2 illustrates a second embodiment of a powder measuring apparatus of the present invention; and Figure 3 illustrates a third embodiment of a powder measuring apparatus of the present invention. Figure 1 shows a first embodiment of the invention. A measuring pump 1, which includes between two side plates 2, 3 a measuring disk 4 which is driven by rotation by means of a pump shaft 18 by means of a mechanism not shown, comprising an inlet 6 and an outlet 7. measuring disc 4 adapts the measurement of holes or measuring chamber that are distributed on its circumference. The inlet 6, the outlet 7 are radially spaced from the axes of rotation of the pump shaft 18 with respect to the measuring chambers. The inlet 6 connects to a powder feed device 13. The powder feed device 13 consists essentially of a feed channel 19, which connects to the inlet 6 of the metering pump 1, a container 20 and a fluid bed 12 coupled thereto. The container 20 holds a powder, in which the air is blown, so that the fluid bed 12 is generated in the container 20. Similarly, the air is blown in the supply channel 19, in such a way that it also contains a bed of fluid.

This causes a mixture of powder air to develop, which is supplied from the container 20, via the feed channel 19 and the inlet 6, to the measuring chambers 21 of the measuring disk 4. By rotating the measuring disk 4, the measuring chambers 21 which are filled at least in part with the powder or the air-powder mixture are moved to the side of the outlet of the measuring pump 1. In a radially spaced relation as the measuring hole 21, with respect to the axes of rotation of the pump shaft 18, the side plate 2 accommodates a suction inlet end and the side plate 3, the outlet 7 or a corresponding outlet chamber, which is connected by means of an injector suction tube 8 to an injection pump 5. By supplying to an injection pump 5, a transported air stream, which is controllable by means of a control element 15, the action of the injection pump 5 generates in the injector suction tube a flu vacuum 10. This vacuum flow 10 causes air to be suctioned off by means of the suction inlet end 9, and this suction air causes the air-powder mixture contained in the respective measuring chamber 21 it coincides with the suction inlet end 9 and the outlet 7 that is to be discharged and that is going to be supplied by the vacuum flow 10 to the injection pump 5 through the injector suction tube. From the injection pump 5, the powder or air-powder mixture achieve the consumption in the desired quantity. As a result of the generation of the vacuum flow 10 by means of the injection pump 5 on the outlet side of the metering pump 1, this achieves that substantially no powder is capable of being deposited at the sealing points between the measuring disk 4. and the side plate 2 and the side plate 3. This reduces the wear of the measuring pump 1 considerably. The connection of the injection pump 5 with the measuring pump of the disc type 1 allows to combine the advantages of both systems and create a reliable, reproducible and exact operating dust measurement system. Figure 2 shows a second embodiment of the invention. The basic construction and the basic operation of the illustrated powder measure the apparatuses according to this second embodiment of the present invention corresponding to those described with reference to Figure 1. Different from the description of Figure 1, a first control element is provided to control the suction air stream to the suction inlet end 9. This first control element is used to directly control the suction air stream and thus the vacuum air stream 10 in the suction tube injector 8, in a certain way with respect to the desired circumstances of the particular request. In addition, downstream of the injection pump 5, a second control element 14 is provided which causes an additional suction air flow to introduce the conveyor line in a controlled manner. This allows influencing the supply of the injection pump 5 itself in a certain way. On the other hand, the downstream of the injector pump 5, a third control element is provided, which is used to control the air flow transported to the injection pump 5. The magnitude of the transported air stream allows control of the rider t eme nte the suction capacity of the injection pump and thus, the vacuum flow 10 and, thus, the discharge of dust or air-powder mixture from the outlet 7 of the metering pump 1.

The side discs 2, 3 are each provided with corresponding cavity spaces 17, through which a coolant flows for purposes of preventing dust or air-powder mixing, overheating in the measuring pump 1. Figure 3 shows a third embodiment of the "invention whose operation corresponds substantially to that described with reference to Figures 1 and 2. Different from the embodiment described with reference to Figure 2, a controller 16 - is provided in addition, which electrically controls a mechanism 22 of the metering pump 1 and the second control element for the additional suction current as well as the third control element for controlling the transported air stream in a way that the injector pressure is controlled as a function of the rotational speed of the metering pump.

Claims (10)

1. The dust measuring device for powder coating, the apparatus comprises a metering pump with a rotationally driven measuring disk arranged between two side plates and an injection pump, the metering pump has an inlet, through which a mixture of air-powder can be supplied to the measuring disk, and an outlet that is connected by means of a suction tube to the injection pump, and from which "the air-powder mixture transported by means of the measuring disk can be Suction separated by a vacuum flow that is generated by the injector pump and enters the metering pump by means of a suction inlet end and is supplied to a consumer.

2. The powder measuring apparatus of claim 1, wherein the injection pump comprises a first control element for controlling the vacuum flow such that it prevents dust from depositing at the outlet and / or between the measuring disk and the side plates.

3. The powder measuring apparatus of claim 1 or 2, wherein a controller is provided, by means of which the injection pump can be controlled in a regulated pressure manner as a function of the rotational speed of the metering pump.

4. The powder measuring device of the indication rei 3, wherein the first control element is disposed upstream of the suction inlet end and controls the supply of an air stream from a source of compressed air at the end of the inlet of suction.

5. The dust measuring apparatus of the rei indication 3 or 4, where for purposes of assisting in the transport action of the pump-injector, an additional controllable air stream can be introduced downstream of the injection pump by means of of a second control element.

6. The powder measuring apparatus of one of the claims 3-5, wherein a third control element is provided to control the air flow supplied to the injection pump.

7. The dust measuring apparatus of the indication 6, wherein the first, second, and third control elements are controlled by means of the controller.

8. The powder measuring apparatus of one of claims 1-7, wherein the air-powder mixture can be generated in a fluid bed maintained in a controller of a powder feed device that is connected to the inlet of the measuring pump.

9. The powder measuring apparatus of claim 8, wherein the fluid bed can be generated in a feed channel of the powder feed device that connects the container to the inlet of the metering pump.

10. The powder measuring apparatus of one of claims 1-9, wherein at least the side plates of the metering pump comprise hollow spaces for the flow of refrigerants.