EP2321622A1

EP2321622A1 - Weighing device

Info

Publication number: EP2321622A1
Application number: EP09778053A
Authority: EP
Inventors: Ervin Hihn
Original assignee: Eisenmann SE
Current assignee: Eisenmann SE
Priority date: 2008-09-04
Filing date: 2009-08-22
Publication date: 2011-05-18
Also published as: CN102144148A; DE102008045762A1; RU2011112449A; WO2010025843A1; RU2502965C2; US20110186358A1

Abstract

The invention relates to a device for continuously weighing powdered media in a tank (12), particularly paint powder in a storage tank (12), comprising a weighing unit (32) having a measurement field (36) on which a compressive force can be exerted, and by which an output signal representing the compressive force exerted on the measurement field (36) can be generated. A guiding device (46) allows forced motion of the tank (12) having a vertical directional component. The tank (12) can further be coupled to the weighing unit (32) by forces by means of a coupling device (102), so that a compressive force that is dependent on the weight of the tank (12) acts on the measurement field (36) of the weighing unit (32) when the tank (12) is coupled to the weighing unit (32).

Description

- -

weighing device

The invention relates to a device for the continuous weighing of pulverulent media in a container, in particular of paint powder in a storage container, with a weighing unit, which has a measuring field, to which a pressure force can be exerted, and by which an output signal can be generated, which stands for the pressure exerted on the measuring field.

Such weighing devices are used for example in powder conveyor systems of the surface technology in the automotive industry in monitoring the promotion of paint powder with which vehicle bodies are coated. In this case, the container is a storage container which is supplied with paint powder from a reservoir and from which paint powder is conveyed to an application device, for example a rotary atomizer, or another consumer. For this purpose, the paint powder is fluidized in a manner known per se in the interior of the storage container, whereby it becomes flowable.

During operation of such a powder conveying system, the amount of paint powder present in the receiving container steadily decreases. When the coating amount of powder in the reservoir vessel finally reaches a lower threshold value, the collecting tank of fresh powder paint must be supplied to ensure continuous operation of the powder transport system and therefore the coating installation, in which the Pul ^¬ verförderanlage is used.

Achieving or falling below this threshold is usually by continuous or at least monitored repeated weighing of the original container with a device of the type mentioned. In weighing devices known from the market, three load cells are used on which the storage container rests. In order to achieve as even as possible a pressurization of the load cells and thereby a sufficiently accurate measurement result, the load cells are arranged on a circle at the same angular distance from each other. The amount of paint powder present in the reservoir is determined in real time by forming the mean value of the three weights determined by the load cells and subtracting the previously determined and therefore known tare weight of the receiver from this mean value.

Due to the necessary averaging of the measurement results of all weighing cells, the measurement result in the known weighing device is subject to an inaccuracy, which may be e.g. in the standard deviation.

Object of the present invention is to provide a weighing device of the type mentioned, in which, with a relatively simple construction, the accuracy of monitoring the amount of powder in a container is increased.

This object is achieved in a weighing device of the type mentioned above in that it comprises:

a) a guide device, which allows a positively guided movement of the container with a vertical direction component;

b) a coupling device, by means of which the container with the weighing unit is coupled in terms of power, so that a compressive force on the measuring field of the weighing unit acts, which depends on the weight of the container when the container is coupled to the weighing unit.

By means of these measures according to the invention, it is possible to determine the weight of the container with the aid of a single weighing unit. Thus, no mean value has to be formed from a plurality of measured values, whereby the accuracy of the weighing result is increased.

By the guide device of the container to be weighed is protected against tilting, but can be moved in the vertical direction. The vertical degree of freedom of the container is necessary so that it can exercise depending on its level a more or less strong weight vertically downwards.

By means of the coupling device, the weight force exerted by the container to be weighed is transferred to the weighing unit. This generates an output signal which stands for the respectively determined weight. After subtracting the known tare weight of the container to be weighed and optionally the weight, which acts on the weighing unit by the coupling device, from this determined weight so the amount of the powdery medium in the container can be calculated.

It is advantageous if the coupling device or the guide device comprises a holding device for the container.

A simple construction is possible if the coupling device is designed as a substantially rigid structural unit and the guide device of the coupling device enables the positively driven movement. In this case, the Coupling unit connected via the holding device to the container, so that the coupling device and the container to be weighed by the .Wiegeeinheit be detected as a unit _t the can.

It has proven to be particularly advantageous if the guide device provides a parallelogram. In particular, when using low-friction bearings, a guide device can be provided, in which the movement of the container counteract only low frictional forces and the weight of the container can be transferred to the weighing unit more or less unadulterated.

It is advantageous if the coupling unit comprises a coupling member which rests on a support portion, in particular with a point-shaped bearing surface, on the measuring field of the weighing unit. In this way, a more accurate transfer of the weight exerted by the container to be weighed weight on the weighing unit is possible.

It has proved to be advantageous if the support portion of the coupling member is curved and preferably hemispherical. In this case, the coupling device can also tilt to some extent with respect to a vertical axis, without this having a negative effect on the measurement result of the weighing unit. Such tilts can e.g. caused by vibrations during operation.

When the weighing unit is a double-beam load cell, existing and established weighing techniques can be used to advantage.

An embodiment of the invention will be explained in more detail with reference to the drawing. In this show: - -

Figure 1 is a perspective view of a weighing device according to the invention; FIG. 2 shows a side view of the weighing device according to FIG. 1;

Figure 3 is a vertical section through the weighing device according to Figures 1 and 2, wherein a load cell can be seen in a side view;

Figure 4 is a perspective view similar to Figure 1 of the weighing device, wherein a storage container for paint powder is supported by the weighing device;

Figure 5 is a side view of the weighing device shown in Figure 4 with storage container.

In FIG. 1, a total of 10 denotes a weighing device for the continuous weighing of a storage container 12 shown in FIGS. 4 and 5. On the storage container 12 will be discussed again below.

The weighing device 10 comprises a U-shaped carrier profile 14 with a base leg 16 and two perpendicular thereto side cheeks 18 and 20. On an end face 22, the support section 14 is connected to a bottom plate 24, for example, welded, which at right angles to the longitudinal axis of the carrier profile 14th runs. In the embodiment shown here, the bottom plate 24 is substantially square and has through holes 26 in their corner regions. By the latter screws can be guided so that the bottom plate 24 can be fixed to the carrier profile 14 on a substrate, whereby a Verkip- pen the weighing device 10 is prevented. On its side opposite the bottom plate 24 front side 28 is between the side walls 18 and 20, an end wall 30 ^ arranged, which runs parallel to the bottom plate 24. The end wall 30 carries on its planar upper surface an elongated double bending beam load cell 32, as it is known per se and in an end region 34 has an upwardly facing measuring field 36 (see Figure 3). Under measuring field is here the area of the load cell 32 to understand on which the weight to be detected must be exercised in order to perform a measurement can. Depending on the weight forces exerted on the measuring field 36, the load cell 32 generates output signals. The load cell 32 is arranged so that its end portion 34 with the measuring field 36 is spaced from the carrier profile 14.

The weighing device 10 also comprises a U-shaped coupling profile 38 with a base leg 40 and two side cheeks 42, 44 extending perpendicular thereto. The coupling profile 38 has a cross-section which corresponds to that of the carrier profile 14, but is shorter in the longitudinal direction than the carrier profile 14 Both profiles 14 and 38 are parallel to each other and are aligned so that their respective side cheeks 18, 20 and 42, 44 assign each other and are aligned.

The two profiles 14 and 38 are movably connected to one another via a guide device 46. The guide device 46 is designed as a parallelogram, so that when a movement of the coupling profile 38 relative to the support profile 14 whose parallel alignment is maintained to each other.

The guide device 46 includes an upper link 48 and a spaced therefrom lower arm 50. These are each arranged with a first end region 48a or 50a between the side cheeks 18, 20 of the carrier profile 14 and with their respective opposite second end region 48b or ■ j50b between the side walls 42, 44 of the coupling profile 38 5. The end areas 48a, 48b and 50a, 50b of the links 48, 50 are only shown in FIG. 3 for the sake of clarity.

The upper link 48 and the lower link 50 are each pivotally connected in their first end portion 48a, 50a via horizontally extending shafts 52 and 54 respectively to the carrier profile 14, which are mounted on the side cheeks 18, 20 of the carrier profile 14 and between these two extend. In a corresponding manner, the upper link 48 and the lower link 50 are mounted pivotably in their second end regions 48b and 50b via horizontal axes 56 and 58 between the side cheeks 42, 44 of the coupling profile 38.

The upper link 48 and the lower link 50 have on undo known bearings 60a, 60b and 62a, 62b, by means of which they are pivotable about the horizontal axes 52 to 58 friction. The bearings 60a, 60b, and 62a, 62b are provided for clarity only in Figure 3 with reference numerals. 5

In the present embodiment, the upper link 48 and the lower arm 50 are formed U-shaped, wherein the bearings 60a, 60b and 62a and 62b are arranged in the side walls parallel to each other and not specifically provided with a Bezugso reference, which is located between the carrier profile 14 and the coupling profile 38 extend. The carrier profile 14 and the coupling profile 38 are aligned with each other so that the coupling profile 38 projects upwards beyond the carrier profile 14 when it assumes a basic position a-5, in which the upper arm 48 and the lower arm - o -

50 are aligned horizontally. This basic position of the coupling profile 38 is shown in Figures 1 to 5. The links 48 and 50 are so long that in this basic position _* , a gap remains between the carrier profile 14 and the coupling profile 38.

The remote from the bottom plate 24 end 64 of the coupling profile 38 is closed with an end wall 66, wherein in the basic position of the coupling profile 38, the measuring field 36 of the load cell 32 is disposed vertically below the end wall 66 and between the flat lower surface 68 and the measuring field 36 of Load cell 32 remains a distance (see Figure 3).

The end wall 66 of the coupling profile 38 carries a vertically projecting from its lower surface 68 down coupling pin 70 which has a hemispherical bearing portion 72 at its end remote from the end wall 66 end (see Figure 3). The length of the coupling bolt 70 corresponds to the distance between the lower surface 68 of the end wall 66 of the coupling profile 38 and the measuring field 36 of the load cell 32 in the basic position of the coupling profile 38. Thus, the coupling pin 70 touches in the basic position of the coupling profile 38 with its support portion 72nd just the measuring field 36 of the load cell 32. By the hemispherical support portion 72 of the coupling pin 70 a minimal contact surface is guaranteed.

In the present embodiment, the load cell 32 protrudes slightly with its end region 34 into a window-like material recess 74 in the base limb 40 of the coupling profile 38. The window 74 is large enough that the coupling profile 38 has a certain freedom of movement.

On the remote from the support section 14 outside 76th _

its base leg 40, the coupling profile 38 carries a holding device 78, by means of which a weighing container to be weighed 12 (see Figures 4 and 5) for paint powder on the ^ coupling profile 38 can be attached. The holding device 78 comprises a support element 80, which has a central plate-shaped portion 82, with which it rests flat on the outer side 76 of the base leg 40 of the coupling profile 38 and is screwed thereto. The plate-shaped section 82 of the support element 80 has, in the direction of the window 74 of the coupling profile 38, a wider area 84a, in which it projects beyond the coupling profile 38 on both sides.

At the end of the broader region 84a pointing in the direction of the window 74 of the coupling profile 38, the plate-shaped section 82 of the support element 80 merges into a first support cheek 86 which extends perpendicularly to the base leg 40 of the coupling profile 38 and from the base leg 40 of the coupling profile 38 adjacent outer edge 88 has a central indentation 90 which is bounded by symmetrically from the outside inwards towards the base leg 40 of the coupling profile 38 to extending flanks.

On the side remote from the first support cheek 86 side, the wider portion 84a of the plate-shaped portion 82 merges into a narrower region 84b, followed by a second Abstützwange 92 connects, which is also perpendicular to the base leg 40 of the coupling profile 38 and one of the indentation 90 of first support cheek 86 corresponding recess 94 has. The recesses 90 and 94 are aligned with each other in the vertical direction.

With its wider region 84a, the support element 80 carries a retaining clip 96, the curvature of which is circular in this case Outer contour of the storage container 12 is adjusted. The headband 96 protrudes with its free ends through the over the coupling profile 38 laterally projecting portions of the wider portion 84a of the support member 80 through what s there corresponding through holes are provided, which are not specifically provided with a reference numeral. The end portions of the retaining clip 96 are provided with a thread and can be secured on the support cheeks 86, 92 remote side of the support member 80 by means of nuts, o which are not specifically provided with a reference numeral. By appropriate rotation of the nuts of the headband 96 can be pulled in the direction of the coupling profile 38, whereby the feed container 12 is pressed into the recesses 90, 94 of the support member 80 and fixed in this position5.

FIGS. 4 and 5 show the weighing device 10 with a storage container 12 clamped in the holding device 78. For this purpose, the retaining clip 96 was first released from the Ab-0 support member 80. The storage container 12 was held in a position in which it lies symmetrically in the indentations 90 and 94 of the support cheeks 86 and 92, respectively. Then, the retaining clip 96 was slid over the cylindrical wall of the storage container 12 and pushed with its free Endberei-5 Chen in the corresponding through holes in the plate-shaped portion 84 of the support member 80 and screwed correspondingly from the back. In this case, the headband 96 was used by turning the nuts on the support member 80 that the Vorlagebe-o container 12 is held securely by jamming.

In the storage container 12 is a template ^¬ container of a powder conveyor, as it is known per se and which interes-5 here Siert not in detail. The feed tank 12 is fed via a Zuführan- - -

Final 98 supplied with paint powder. This paint powder is fluidized in the interior of the storage container 12 in a manner known per se and thus fluidly removed from the storage container 12, 12 via a removal hose 100 and led to an application device not shown here. To the reservoir 12 or from this leading hoses and connections can be fixed tension-free to the support section 14, so that such hoses and compounds do not affect the weighing result.

The holding device 78, together with the coupling profile 38 and the coupling pin 70, a coupling device 102 which exerts a compressive force on the measuring field 36 of the load cell 32, which depends on the weight of the more or less filled storage container 12.

The coupling bolt 70 presses with a force on the measuring field 36 of the load cell 32, which is determined by the weight of the storage container 12 and the weight of the components belonging to the coupling device 102. Due to the pressure exerted on the measuring field 36, the measuring cell 32 generates output signals which represent these pressure forces.

By the guide means 46 of the storage container 12 is forcibly guided in its movement, in which he can move in particular in the vertical direction, ie with a vertical directional component. In the exemplary embodiment shown here, the movement possible for the storage container 12 also includes a horizontal directional component due to the parallelogram guide. However, this is irrelevant for the pressure force exerted on the measuring field 36 of the load cell 32.

In the course of a coating process, the amount of paint powder present in the reservoir 12 changes. From- _

dependent on the amount of paint powder which is located in the storage tank 12, also responsive to the measuring field 36 of the weighing cell 32 via the coupling member 70 exerted ■ ^■ ..Druck, which is reflected in a corresponding change in output s signal of the load cell 32 changes ,

As indicated in FIG. 3, the load cell 32 communicates via a data line 104 with a controller 106, which visualizes the signals output by the load cell 32 on a monitor 108.

If the output signal of the weighing cell 32 reflects a quantity of paint powder in the storage container 12 which falls below a certain threshold value, the controller 106 triggers a filling of the storage container 12 via its feed connection 98, which is indicated by an arrow 110 in FIG. The controller 106 is also transmitted (arrow 112) further operating parameters of the system, in which it is used, whereby the controller 1060 can be used to control the entire coating plant, which can generate corresponding output signals.

During the filling of the storage container 12, the weight increase of the same and thereby the status of the filling process by the visualization on the monitor 108 can be tracked by an operator.

If paint powder is applied from the reservoir 12 by means of the above-mentioned application device on a vehicle body, the weight loss can be tracked by the visualization on the monitor 108 by an operator in a corresponding manner. 5 From the load cell 32 to the controller 106 übermit- The powder discharge quantity of the application device can be calculated within a time period predetermined by the operating personnel and displayed on the monitor 108. As a result, it is possible to determine to a high degree exactly which quantity of paint powder was applied to a specific vehicle bodywork during the painting process. Knowing the amount of powder applied to every vehicle body in the course of a production day helps to maintain consistent paint quality in a large number of painted vehicle bodies.

If the powder ejection quantity of the application device is reduced or increased during a coating operation in comparison to a preceding coating operation, which alters and generally worsens the coating result compared to the preceding coating operation, the further coating process can optionally be interrupted immediately and investigation measures can be taken immediately to determine the reason for changing the powder ejection amount of the application device.

A change in the normal work processes, which has an influence on the amount of application per vehicle body, is thus indicated immediately after their occurrence, without any time delays, during which further

Vehicle bodies painted with possibly reduced compared to previous vehicle bodies quality.

By the weighing device 10, the amount of paint powder in the storage container 12 can be followed continuously or repeatedly after any period of time, with only one load cell is needed. An elaborate alignment of the storage container 12 or a plurality of side guides to prevent the storage container 12 against tilting against a _

stabilizing a vertical axis is not required.

^ In addition, the measurement accuracy is increased compared to a weighing device which uses several load cells. In the weighing device 10, no mean value has to be formed, which always involves a certain inaccuracy. Rather, only a single measurement result has to be evaluated, which is directly representative of the quantity of paint powder present in the reservoir 12.

Claims

claims

1. Apparatus for the continuous weighing of powdered media in a container (12), in particular of

Paint powder in a storage container (12), with

a weighing unit (32) which has a measuring field (36) on which a pressure force can be exerted and by which an output signal can be generated that represents the pressure force exerted on the measuring field (36),

characterized in that the device comprises:

a) a guide device (46), which allows a positively driven movement of the container (12) with a vertical direction component;

b) a coupling device (102), by means of which the container (12) with the weighing unit (32) can be coupled in terms of forces, so that a compressive force acts on the measuring field (36) of the weighing unit (32), which depends on the weight of the container (12) when the container (12) is coupled to the weighing unit (32).

2. Weighing device according to claim 1, characterized in that the coupling device (102) or the guide device (46) comprises a holding device (78) for the container (12).

3. Weighing device according to claim 2, characterized in that the coupling device (102) is designed as a substantially rigid structural unit (102) and the guide means (46) of the coupling device (102) enables the positively driven movement.

4. Weighing device according to one of claims 1 to 3, characterized in that the guide device (46)

^ provides a parallelogram.

5. Weighing device according to one of claims 1 to 4, characterized in that the coupling device (102) comprises a coupling member (70), which over a support portion (72), in particular with a point-shaped bearing surface, on the measuring field (36). the weighing unit (32) rests.

6. Weighing device according to claim 5, characterized in that the support portion (72) of the coupling member (70) is curved.

7. Weighing device according to claim 6, characterized in that the support portion (72) of the coupling member (70) is hemispherical.

8. Weighing device according to one of claims 1 to 7, characterized in that the weighing unit (32) a

Double bending beam load cell (32) is.