DEVICE FOR PUMPING VISCOUS MATERIAL

Abstract

An apparatus for the conveying of viscous material from a container has a conveyor pump, which has a conveyor cylinder and a conveyor piston that can be moved forward and back in the conveyor cylinder, and has a measuring device for measurement of the speed of the conveyor piston. The measuring device has a control unit for control of the conveying of the viscous material in dependence on the measured speed of the conveyor piston and a waste line is branched off from a conveying line for the viscous material, which is connected to the conveyor pump, and using the control unit the conveying line can be blocked and the waste line can be released.

Description

The invention relates to an apparatus for conveying of viscous material according to the preamble of claim 1 as well as to a method for the conveying of viscous material, in which such an apparatus is used.

Apparatuses are known that are used for the conveying of, for example, adhesives, sealing compounds or insulating compounds from a container to a processing station. They find use in particular in the automotive industry, when viscous materials must be applied onto vehicle body parts. Usually, such apparatuses have a follower plate, which rests on the surface of the material present in the container and follows this surface when the material level descends. For this purpose, a lifting device is then provided, which is used for lowering and raising of the follower plate. The material is withdrawn from the container by means of a conveyor pump connected to a material outlet in the follower plate, wherein the follower plate is slaved to the material surface. In this connection, it is also possible that the follower plate additionally presses on the material surface so that, by virtue of this pressure, the material is pressed into the material outlet, while the follower plate bears sealingly on a circumferential container wall. If air bubbles are present in the container, however, this is not perceptible prior to the application of the material. But when material containing air bubbles is conveyed and applied onto a workpiece, this usually causes the applied material to be unable to develop its adhesive, sealing or insulating effect sufficiently. Oftentimes, the structural parts coated in such a way are then unfit for further processing and must be discarded as scrap.

An apparatus of the type mentioned in the introduction is known from DE 197 13 938 A1. This conveyor apparatus for viscous material has a measuring sensor, which determines the speed of the piston rod of the pump that conveys the viscous material. The measuring sensor is used to keep the speed of the conveyor piston connected to the piston rod constant by means of a control device. A similar apparatus is known from DE 20 2013 009 164 U1. This apparatus has a measured-value transmitter for control of the conveyor volume flow. However, neither of the two apparatuses is suitable for detecting air bubbles in the material being conveyed.

It is therefore the task of the invention to further develop an apparatus of the type mentioned in the introduction in such a way that rejects may be prevented better.

This task is accomplished according to the invention by an apparatus having the features of claim 1 as well as by a method having the features of claim 10. Advantageous further developments of the invention are subject matter of the dependent claims.

The invention is based on the knowledge, discovered by the Applicant, that the speed of the conveyor piston during the conveying process may vary in a manner dependent on the material consistency. The Applicant has found by experiments that the speed of the conveyor piston during the delivery stroke is constant at least within a tolerance range provided the material consistency remains constant. If the material being conveyed contains air bubbles, this leads to a significant change of the speed of the conveyor piston during the delivery stroke. On the basis of this knowledge, it is therefore proposed that the speed of the conveyor piston during the delivery stroke be measured by means of a measuring device, so that a change of material consistency and especially the presence of air bubbles may be inferred from a change of the measured speed, so that appropriate measures may be initiated. For this purpose, the measuring device has a control unit for control of the conveying of the viscous material in dependence on the measured speed of the conveyor piston. The control unit evaluates the measured values of the measuring device and automatically initiates measures upon a deviation of the measured speed from a predetermined target speed. In addition, it is provided that a waste line is branched off from a conveying line for the viscous material, which line is connected to the conveyor pump and through which the material is being fed to the processing station, and that the conveying line may be blocked and the waste line released by means of the control unit. The waste line leads expediently to a waste container, in which the material found to be unprocessable may be diverted.

The measuring device expediently has a distance-measuring unit for time-independent measurement of the distance traveled by the conveyor piston. The distance-measuring unit is preferably an absolute-value transmitter. In addition, it is preferred that the conveyor piston is connected mechanically to the distance-measuring unit. This may take place in that the conveyor pump has a piston rod, which projects from the conveyor cylinder, is connected in fixed manner to the piston rod and is connected rigidly by way of connecting means to a movable element of the distance-measuring unit, and on which a drive unit also expediently acts. The movement of the conveyor piston is then transmitted directly to the movable element of the distance-measuring unit.

It may be provided that an operator-control person intervenes in the conveyor process when a significant deviation of the speed of the conveyor piston from a predetermined target speed exists. However, it is preferred that measures are taken automatically in such a case, in order to prevent the production of rejects.

If, in the further course of the conveying process, a speed of the conveyor piston that lies within a predetermined tolerance range around the predetermined target speed is then again measured by the measuring device, so that it is to be assumed that the material being conveyed no longer contains any air bubbles, the control unit automatically changes over and blocks the waste line with simultaneous release of the conveying line. For this purpose, a valve, for example a 2/2-way valve, may be provided at the place at which the waste line branches off from the conveying line. When the waste container is filled with material, it may either be emptied and reused or else it is disposed of and replaced by a new, empty container.

The invention will be explained in more detail in the following on the basis of an exemplary embodiment illustrated schematically in the drawing, wherein

FIG. 1 shows a perspective view of a conveyor apparatus and

FIG. 2 shows a front view of the conveyor apparatus according to FIG. 1.

The apparatus 10 illustrated schematically in the drawing is used for the conveying of viscous material such as adhesive, sealing compound or insulating compound from a drum-like container, not illustrated in more detail. In the exemplary embodiment shown here, the conveyor apparatus 10 has a follower plate 12, which is designed to seal a container that is open on an upper side of the container. During the conveying process, the follower plate 12 additionally bears in annularly sealing manner on the inside face of a circumferential container wall extending to the upper side of the container. In addition, the follower plate 12 bears on the material surface in the container. It is mounted on a lifting device 14, with which it may be lowered in a manner following the descending material level in the container as well as, after emptying of the container, be raised and removed therefrom. In the follower plate 12, a material outlet is disposed, which is not illustrated in more detail in the drawing, and on which a conveyor pump 16 connected in fixed manner to the follower plate 12 is attached in order to convey material from the container via the material outlet into a conveying line 18 leading to a processing station. The conveyor pump 16 has a conveyor cylinder 20 mounted in fixed manner on the follower plate 12 as well as a conveyor piston—not illustrated in the drawing—which can be moved forward and back in the conveyor cylinder 20, and the linear movement of which in the conveyor cylinder 20 sucks material through the material outlet into the conveyor cylinder 20 and forces the material from the conveyor cylinder 20 into the conveying line 18.

The conveyor apparatus 10 additionally has a measuring device 24, with which the speed of the conveyor piston during the delivery stroke may be measured. The measuring device 24 has a distance-measuring unit in the form of an absolute-value transmitter 26, the housing of which is mounted on the lifting device 14. A piston rod 28 connected in fixed manner to the conveyor piston is guided upwardly out of the conveyor cylinder 20 and by means of connecting rods 30 is connected rigidly to a movable element of the absolute-value transmitter 26. The distance-measuring device 24 additionally has a control unit 32, which controls the conveying of the viscous material in dependence on the measured speed of the conveyor piston. The control unit 32 recognizes when the measured speed of the conveyor piston lies outside a tolerance range by a predesignated target speed, which suggests that the consistency of the material being conveyed has changed so much that its suitability is in question. In this case, the control unit 32 operates a valve 34, so that the material being conveyed is conveyed not to the processing station but instead into a waste line 36, which is branched off from the conveying line 18 and leads to a waste container 38. If the control unit 32 recognizes that the speed of the conveyor piston again lies within the tolerance range, it operates the valve 34 yet again and the viscous material is again conveyed via the conveying line 18 to the processing station.

In summary, the following is to be stated: The invention relates to an apparatus 10 for the conveying of viscous material from a container, with a conveyor pump 16, which has a conveyor cylinder 20 and a conveyor piston that can be moved forward and back in the conveyor cylinder 20. According to the invention, a measuring device 24 is provided for measurement of the speed of the conveyor piston.

Claims

1. An apparatus for the conveying of viscous material from a container, with a conveyor pump (16), which has a conveyor cylinder (20) and a conveyor piston that can be moved forward and back in the conveyor cylinder (20), and with a measuring device (24) for measurement of the speed of the conveyor piston, wherein the measuring device (24) has a control unit (32) for control of the conveying of the viscous material in dependence on the measured speed of the conveyor piston and wherein a waste line (36) is branched off from a conveying line (18) for the viscous material, which line is connected to the conveyor pump (16), and by means of the control unit (32) the conveying line (18) can be blocked and the waste line (36) can be released.

2. The apparatus according to claim 1, wherein the measuring device (24) has a distance-measuring unit (26) for time-independent measurement of the distance traveled by the conveyor piston.

3. The apparatus according to claim 2, wherein the conveyor piston is connected mechanically to the distance-measuring unit (26).

4. The apparatus according to claim 3, wherein the conveyor pump (16) has a piston rod (28), which projects from the conveyor cylinder (20), is connected in fixed manner to the conveyor piston and is connected rigidly by way of connecting means (30) to a movable element of the distance-measuring unit (26).

5. The apparatus according to claim 2, wherein the distance-measuring unit (26) is an absolute-value transmitter.

6. The apparatus according to claim 1, wherein the waste line (36) leads to a waste container (38).

7. The apparatus according to claim 1, further comprising a follower plate (12) for sealing of the container on an open upper side of the container, which has a material outlet to which the conveyor pump (16) is attached.

8. A method for conveying of viscous material from a container by use of the apparatus (10) according to claim 1, wherein the viscous material is conveyed in the conveying line (18) when the measured speed of the conveyor piston lies in a predetermined tolerance range around a predetermined target speed, and wherein the viscous material is conveyed in the waste line (36) when the measured speed of the conveyor piston lies outside the tolerance range.