CN108318099B

CN108318099B - Device for monitoring a metering and dispensing apparatus

Info

Publication number: CN108318099B
Application number: CN201711182139.2A
Authority: CN
Inventors: 马丁·路透
Original assignee: Marco Systemanalyse und Entwicklung GmbH
Current assignee: Marco Systemanalyse und Entwicklung GmbH
Priority date: 2017-01-16
Filing date: 2017-11-23
Publication date: 2020-02-21
Anticipated expiration: 2037-11-23
Also published as: DE102017100702A1; JP2018116056A; JP6527971B2; KR20180084658A; CN108318099A; KR102012820B1

Abstract

A device for monitoring a metering device comprises a drop receiving element, onto the upper side of which drops can be applied by the metering device. An image acquisition and evaluation device for determining the diameter of the drops on the drop receiving element and a scale for determining the weight of the drops are additionally provided.

Description

Device for monitoring a metering and dispensing apparatus

Technical Field

The invention relates to a device for monitoring a metering device which meters liquid medium in the form of drops.

Background

Bonding processes are required for mass production steps in the manufacture of electronic components and instruments. In order to avoid damage to the workpiece or to the structural elements on the workpiece, the adhesive is applied contactlessly by spraying, i.e. by means of so-called spray valves. As the size of the adhesive surfaces becomes smaller and smaller, the demands placed on the metering systems used for this purpose with regard to process reliability, accuracy and reproducibility increase significantly.

Disclosure of Invention

The object of the invention is to create a device for periodically and automatically checking the metering device, with which both the drop size and the position of the metered drops can be determined.

This object is achieved by the feature and in particular by the fact that the device comprises a drop receiving element, on the upper side of which drops can be applied by the metering and dispensing device when the metering and dispensing device is in its metering and dispensing position. The device furthermore comprises an image acquisition and evaluation device for determining the diameter of the drop on the drop receiving element and a scale for determining the weight of the drop.

With the device according to the invention, the diameter of the drop and the weight of the drop and thus the volume of the drop can be determined, so that, in the event of a deviation from the preset values, a correction of the process parameters controlling the metered dispensing can be carried out. In contrast to known systems, in which the metered dispensing volume is typically determined by averaging weight measurements of, for example, 100 or 1000 drops, which are metered into a container on a scale, the volume and size of an individual drop can be derived very precisely according to the invention.

Advantageous embodiments of the invention are described in the description, the figures and the dependent claims

According to a first advantageous embodiment, the drop receiving element is movable in the device. In this way, a plurality of droplets can be analyzed in the same device and the individual droplets to be measured can be applied to the blank regions of the droplet receiving element by moving the droplet receiving element, in particular in a single step.

According to a further advantageous embodiment the drop receiving element can be transparent or translucent, so that drops applied to the drop receiving element can be optically analyzed from below the drop receiving element. This in turn has the advantage that the image pick-up of the image acquisition and evaluation device, for example a camera, can be arranged directly below the drop arrangement, whereby the measurement accuracy is increased.

According to a further advantageous embodiment the drop receiving element can be configured in the form of a strip and in particular comprises a foil strip or a film strip. Such a foil or film strip can be produced cost-effectively as a disposable component, wherein at the same time an environmentally friendly and cost-effective disposal is ensured.

It may furthermore be considered advantageous if the drop receiving element is arranged on a unrolling and rolling-up mechanism, since in this case such a section of the drop receiving element (i.e. the section to which the drops have been applied) can be rolled up after optical analysis and weight derivation. While the drop receiving element can be unwound or unwound from a supply.

According to a further advantageous embodiment, the image acquisition and evaluation device can have a single image recording device, for example a single camera. The manufacturing costs can be kept low by using a single image collector. It is not necessary to combine or jointly analyze or evaluate the images of more than one camera at the same time.

According to a further advantageous embodiment, the image acquisition and evaluation device can have an image acquisition device whose optical axis forms an angle with a perpendicular to the drop receiving element, wherein the angle can be, in particular, approximately 15 to 25 °, in particular approximately 10 °. With such a tilting of the image pick-up, in which the optical axis of the image pick-up is not oriented perpendicular to the applied drops, the image pick-up can be used to optically capture both the drops and the regions outside the drops, so that the metering device itself can also be optically evaluated when it is in its metering position. In this way, it can also be ascertained by means of the image acquisition and evaluation device whether contamination is present at the nozzle of the metering and dispensing device, for example, adhering medium, particles or hardened medium in the nozzle channel or at the nozzle. In this connection, it may be considered advantageous to acquire simultaneously with the image acquisition and evaluation device an image region of a droplet situated on the droplet receiving element and an image region of the metering device in its metering position. This shortens the analysis time and allows the evaluation of the unique image to analyze not only the size of the drops but also the state of the metering device.

When the image pick-up of the image acquisition and evaluation device is located below the drop receiving element, it is possible in a simple but precise manner to derive not only the drop size but also the state of the metering and dispensing device.

In order to improve the evaluation of the metering device above the drop receiving element in its metering position, the image acquisition and evaluation device can have a mirror surface, since an image capture device of such a mirror image acquisition and evaluation device can also optically capture regions which would otherwise be obscured by the drops themselves.

According to a further advantageous embodiment, the scale can have a piezoelectric element which is arranged below the drop receiving element. In particular when the drop receiving element is movable in the device, drops applied to the drop receiving element can be first analyzed by means of the image acquisition and evaluation device and then positioned above the piezoelectric element position by movement of the drop receiving element, which is an integral part of the scale. In this position the weight of the applied drop can be weighed, so that the volume of the drop can then be derived.

According to a further advantageous embodiment, the balance can determine the weight of the drop by evaluating the resonance curve of the piezoelectric element. The phase shift, which is generated by measuring the resonance curve or the oscillation frequency of the piezoelectric element with a drop on top of the scale and without a drop on top of the scale, can be measured by the weighing electronics integrated into the scale. The impedance matching of the piezoelectric element is changed by the mass of the liquid droplet and thus likewise leads to a shift in the resonant frequency and amplitude. The mass of the drop can then be derived very precisely from a comparison of the two resonance curves, and the volume of the drop can then also be determined by the specific mass known for the respective medium.

According to a further advantageous embodiment, the position of the drop on the drop receiving element can also be determined by means of the image acquisition and evaluation device, so that it can additionally be recognized whether the position of the drop is precisely provided from the middle of the nozzle outlet of the metering and dispensing device in its metering and dispensing position, or whether the drop is ejected at a slight inclination and is correspondingly displaced relative to the axis of the nozzle outlet. To determine the angle of droplet ejection, the determination of the droplet position may be performed multiple times but at least twice with different spacing between the nozzle outlet and the droplet receiving element. The metered dispense angle can then be calculated from the relationship between the movement of the drop position and the change in pitch. This is particularly advantageous for devices having a nozzle channel which is inclined relative to the drop receiving element, for example, in order to insert a dose into a lateral recess of a housing.

The determination of the droplet size and the droplet position can in principle be carried out automatically by the image acquisition and evaluation device using corresponding image processing software or image recognition software. In this connection, it can be advantageous if the image acquisition and evaluation device has an interface which is connected to a control unit of the metering and dispensing device, wherein the metering and dispensing position and/or the metering and dispensing quantity of the metering and dispensing device can be changed by the image acquisition and evaluation device. In this way, the droplet size and the position of the droplets can be automatically and fully automatically changed or adapted when deviations from the desired parameters can occur during operation.

According to a further advantageous embodiment of the invention, the device according to the invention can have a cleaning module for a metering device, wherein the cleaning module has a cleaning belt guided by rolling elements and the rolling elements have spherical rolling surfaces. With such a cleaning module metering and dispensing device, the metering and dispensing needle can be placed against the rolling surface of the projection, so that the cleaning tape can then be moved through between the rolling surface and the metering and dispensing needle in order to clean the metering and dispensing needle. The protruding design of the rolling surface ensures that the metering needle or the nozzle outlet of the metering device is contacted and cleaned as sufficiently as possible by the cleaning belt. This effect can be maximized in that the rolling surface is configured as a sphere.

According to a further advantageous embodiment, the device can have a cleaning module for the metering and dispensing apparatus, wherein the cleaning module has a vacuum chamber with an access opening provided with a sealing element. Such a cleaning module is suitable for metering and dispensing devices with flat nozzles, since in this case the metering and dispensing device can be placed on the sealing element of the cleaning module until the seal is closed off by the flat nozzle opening. The medium can then be sucked away from the nozzle channel by generating a negative pressure in the chamber, since the sealing element seals the vacuum chamber from the environment. For a particularly good seal, it can be advantageous in this connection if the sealing element has an annular projection.

Liquid media are understood for the purposes of the present application to be non-gaseous fluid media, in particular binders or chemical components which have to be metered precisely in very small quantities.

The image capture device can be understood as a camera, for example, but can also be a camera chip, a CCD module or a combination of such a component and an optical component, such as a lens or the like.

The metering position of the metering device is understood to be the position in which the metering device is located when it delivers (ejects) the drops onto the drop receiving element.

The cleaning module described in connection with the monitoring device according to the invention can advantageously be used and applied not only in combination with the monitoring device but also without the monitoring device.

Drawings

The invention is described below purely by way of example with the aid of advantageous embodiments and with reference to the accompanying drawings. In the figure:

FIG. 1 shows a perspective view of a module for monitoring a metered dispensing device;

fig. 2 shows the module of fig. 1 with the side part removed;

FIG. 3 shows a partially cut-away cross-sectional view of the module of FIG. 1 mounted on a substrate;

FIG. 4 shows a partial enlargement of FIG. 2;

FIG. 5 shows a perspective view of a cleaning module for a flat nozzle; and

figure 6 shows a partially cut-away cross-sectional view of a cleaning module for a metering dispense needle.

Detailed Description

The device shown in fig. 1 for monitoring a metering device for metering a liquid medium in the form of drops has a module 10 with a square base body, in which a drop receiving element 12 in the form of a transparent or translucent foil strip is movable, which can be unwound from a supply reel 14 and wound up on a receiving reel 16. The receiving reel 16 is provided with flanges 17 on both sides so that the medium applied to the drop receiving element 12 in the direction of arrow D is not pressed out when being rolled up and pollutes the environment. The flange 17 furthermore makes it possible to better guide the rolled-up foil strip.

The foil strip, more precisely the drop receiving element 12, is driven by an electric motor 18, in particular a stepping motor, which drives a reel core 20 (see fig. 3). Both the outgoing reel 14 and the receiving reel 16 are exchangeable and can be connected to the reel core in a spring-retaining manner by means of a slip clutch. For the unwinding spool 14, the spool core is connected to its associated bearing shaft 22 (fig. 3) in a slidable manner by means of a spring and a piston, wherein the contact force for this sliding connection can be selected to be low, i.e. such that the spool 14 brakes only slightly, so that the foil strip remains taut during unwinding. The reel 16 for winding up is connected with the reel core by means of the same slip clutch, wherein the reel core 20 for the reel 16 for winding up is fixedly pushed with a threaded fastener to the drive shaft 23 of the motor 18.

The motor 18 can be actuated by a controller, not shown in detail, of the image acquisition and evaluation device 25 in such a way that the drop receiving element 12 is unwound from the supply reel 14 and wound up onto the take-up reel 16 in steps. The drops metered onto the drop receiving element 12 here move from left to right (from above).

The drops applied by the metering device 30 (fig. 4) onto the drop receiving element 12 in the direction of the arrow D (fig. 1) are analyzed by an image acquisition and evaluation device 25, for example by means of an image collector in the form of a single camera 26, which is arranged below the drop receiving element 12 and thus acquires images from below the drop receiving element 12.

As shown in FIG. 4, the optical axis OA of camera 26 is oriented so that it forms an angle of about 10 with a perpendicular L to the drop receiving element 12α. In other words, optical axis OA of camera 26 is not oriented perpendicular to, but oblique to, drop receiving element 12, so that it can be simultaneously acquiredAn image area of a drop (not shown) on the drop receiving element 12 and an image area of the metering device 30 in its metering position. In order to also be able to optically detect the metering nozzle 32 (fig. 4) of the metering device 30 itself, which is obscured by the metered drops, the device shown in fig. 4 has a mirror 34 (see also fig. 2) which is arranged laterally and obliquely with respect to the optical axis OA and with which the image limited by the marginal rays S1 and S2 can be detected.

Fig. 1, 2 and 4 furthermore show that the device according to the invention is provided with a scale having a piezo element 40 which is arranged below the drop receiving element 12, wherein the drop receiving element is placed flat on the piezo element. The foil strip of the drop receiving element 12 is guided under a certain stress through the end face of the approximately square piezoelectric element 40 in such a way that the foil strip rests flat on the piezoelectric element 40. For this purpose, the housing of the module 10 is slightly bent in the region of the mounting of the piezo element 40 and the piezo element 40 itself in order to ensure a good contact of the foil strip against the piezo element. The piezoelectric element 40 is connected to electronics (not shown) integrated into the module 10. With this electronics, which may be an integral part of the scale, the resonance curve of the oscillator or the oscillation frequency can be measured by measuring the phase shift of the piezoelectric element 40, for example separately in the case of non-application of a droplet and in the case of application of a droplet. The mass of the drop can be inferred very precisely by the induced shift in the oscillation frequency and the resonance amplitude and the volume of the drop can be determined by the specific gravity of the drop.

By integrating the above-described device for performing an automatic evaluation of the droplet size, droplet position and droplet weight into a superordinate controller of the metering and dispensing device, which superordinate controller also integrates a controller of a robot in which the metering and dispensing device is located, an automatic adaptation and adjustment of the metering and dispensing process is possible. If the droplet is too small or too large, the system can here correct the metered dispensing amount by matching the opening time or opening lift of the valve, and if the droplet is recognized by the image acquisition and evaluation device as moving towards the nozzle axis, the valve position of the robot as it moves can be adjusted accordingly.

As shown in fig. 3, the module 10 can be positioned on the base plate 11 of the robot or in the working area of the robot, wherein the fixation is performed by two

magnets

28 and 30 fixed at the module 10. For precise positioning, two pins are also provided, namely a short pin 29 between the two

magnets

28 and 30 and a long pin 31 which engages in the laterally open recess 27 in the module 10, which are connected to the base plate 11. The locking of the cleaning modules described below (fig. 5 and 6) is effected in the same way. The electrical contacts for the power supply and communication of the module 10 are realized by plug connectors 42 (fig. 4) which are inserted into corresponding counterparts of the base plate 11 during the assembly and the locking of the module.

A cleaning module 10' for a metering device 30 is shown in fig. 5. In a base body constructed analogously to the base body of the module 10, two rollers 14 'and 16' are provided in a manner analogous to that in the module 10, wherein the nonwoven web 50 is unwound from the roller 16 'and wound up by the winding roller 14', which roller 14 'in turn is driven by the motor 18'. The nonwoven belt 50, which is used here as a cleaning belt, is guided between the two reels 14 'and 16' via a rolling element 52, which has a spherical rolling surface and is rotatably mounted on a shaft 54. The rolling elements 52 are designed as rubber rollers and form a spherical surface in the region of the adjacent non-woven belt 50 as a rolling surface, i.e., the non-woven belt 50 is curved there both in the conveying direction and transversely thereto. This ensures that the needle 32 (fig. 4), or rather the nozzle outlet of the metering and dispensing device 30, is contacted and cleaned by the nonwoven. For cleaning, the metering and dispensing device 30 is moved by the robot over the cleaning module 10' and lowered down to the nonwoven 50. The non-woven belt 50 is then moved by the motor 18', whereby the non-woven belt wipes along the nozzle outlet and thereby cleans the nozzle outlet. The cleaning module 10' is suitable in principle for all nozzle types, but can be used particularly advantageously for flat nozzles.

To activate the motor 18', a proximity sensor can be integrated into the module 10', which proximity sensor detects the proximity of the metering and dispensing device. It is also possible to fit a sensor laterally to the nonwoven strip 50 to be unwound, while observing it, which sensor can ascertain when the roll is almost empty, or rather when only a small amount of residue remains on the roll.

Figure 6 shows another cleaning module 10 "having a vacuum chamber 60 in which a negative pressure can be generated. This negative pressure can be generated, for example, by means of a venturi nozzle and a pressure regulating valve (proportional valve) integrated in the module 10 ″. Alternatively, such a negative pressure can also be applied from the outside via a corresponding connection. The underpressure chamber 60 of the module 10 ″ has an access 62 provided at its upper side, which access is provided with a sealing element 64 made of a suitable rubber material. The sealing element 64 has an annular projection 66 on its upper side, which is formed in the center of a passage channel 68 in the sealing element 64. In this way, the metering and dispensing device 30 with the nozzle needle 32 can be robotically advanced over the module 10 ″ and lowered until the seal 64 is closed by the nozzle and the nozzle outlet is thereby connected in a sealed manner to the vacuum chamber 60 with respect to the environment. A negative pressure can then be generated in the chamber 60 and the medium located at the nozzle 32 and also in the nozzle channel can be drawn off. It is also possible to monitor, by means of an optional pressure sensor integrated in the module 10", whether a sufficient underpressure can be generated and accordingly whether the valve is also sealed on the module 10". Cleaning of the nozzle needle 32 and likewise of the nozzle channel is important in order to avoid hardening of the medium in the nozzle channel during closing of the valve.

The cleaning module 10 ″ is suitable in principle for all nozzle types, but can be used particularly advantageously for nozzle needles, since they can be inserted into the underpressure chamber 60 and cleaned there.

Claims

1. A device for monitoring a metering and dispensing apparatus (30) for metering and dispensing a liquid medium in the form of drops, characterized in that the device comprises

A drop receiving element (12) onto the upper side of which drops can be applied by the metering device (30) in its metering position,

an image acquisition and evaluation device (25,26) for determining the diameter of the drop on the drop receiving element (12), an

A scale (40) for determining a weight of the droplets,

with the image acquisition and evaluation device (25,26) an image of the drops on the drop receiving element (12) and of the metering device (30) in its metering position can be acquired simultaneously,

the image acquisition and evaluation device (25) has an image acquisition device (26) which acquires images from below the drop receiving element (12).

2. The apparatus of claim 1, wherein the first and second electrodes are disposed on opposite sides of the housing,

it is characterized in that the preparation method is characterized in that,

the drop receiving element (12) is movable in the device.

3. The apparatus of claim 1, wherein the first and second electrodes are disposed on opposite sides of the housing,

it is characterized in that the preparation method is characterized in that,

the drop receiving element (12) is transparent or translucent.

4. The apparatus of claim 1, wherein the first and second electrodes are disposed on opposite sides of the housing,

it is characterized in that the preparation method is characterized in that,

the drop receiving element (12) is designed in the form of a strip.

5. The apparatus of claim 4, wherein the first and second electrodes are disposed on opposite sides of the substrate,

it is characterized in that the preparation method is characterized in that,

the drop receiving element (12) comprises a foil strip or a film strip.

6. The apparatus of claim 1, wherein the first and second electrodes are disposed on opposite sides of the housing,

it is characterized in that the preparation method is characterized in that,

the drop receiving element (12) is arranged on a unrolling and rolling mechanism (14, 16).

7. The apparatus of claim 1, wherein the first and second electrodes are disposed on opposite sides of the housing,

it is characterized in that the preparation method is characterized in that,

the image acquisition and evaluation device (25) has a single image collector (26).

8. The apparatus of claim 1, wherein the first and second electrodes are disposed on opposite sides of the housing,

it is characterized in that the preparation method is characterized in that,

the image acquisition and evaluation device (25) has an image acquisition element (26) whose optical axis OA has an angle α with a perpendicular L to the drop receiving element (12).

9. The apparatus of claim 8, wherein the first and second electrodes are disposed on opposite sides of the substrate,

characterized in that the included angle α is an included angle of 15-25 degrees.

10. The apparatus of claim 1, wherein the first and second electrodes are disposed on opposite sides of the housing,

it is characterized in that the preparation method is characterized in that,

the image acquisition and evaluation device (25,26) has a mirror (34) for acquiring an image of the metering and dispensing device (30,32) above the drop receiving element (12) in its metering and dispensing position.

11. The apparatus of claim 1, wherein the first and second electrodes are disposed on opposite sides of the housing,

it is characterized in that the preparation method is characterized in that,

the scale has a piezoelectric element (40) arranged below the drop receiving element (12).

12. The apparatus of claim 11, wherein the first and second electrodes are disposed in a substantially cylindrical configuration,

it is characterized in that the preparation method is characterized in that,

the drop receiving element (12) is placed in a planar manner on the piezoelectric element (40).

13. The apparatus according to claim 11 or 12,

it is characterized in that the preparation method is characterized in that,

the scale derives the weight of the drop by analyzing the resonance curve of the piezoelectric element (40).

14. The device of any one of claims 1 to 12,

it is characterized in that the preparation method is characterized in that,

the image acquisition and evaluation device (25,26) is used to determine the position of the drop on the drop receiving element (12).

15. The device of any one of claims 1 to 12,

it is characterized in that the preparation method is characterized in that,

the image acquisition and evaluation device (25,26) has an interface which is connected to a control of the metering and dispensing device (30), wherein the metering and dispensing position and/or the metering and dispensing quantity of the metering and dispensing device (30) can be changed by means of the image acquisition and evaluation device (25, 26).

16. The device of any one of claims 1 to 12,

it is characterized in that the preparation method is characterized in that,

a cleaning module (10') is provided for the metering device (30), said cleaning module having a cleaning belt (50) guided by a rolling element (52), wherein the rolling element (52) has a convex rolling surface.

17. The apparatus of claim 16, wherein the first and second electrodes are disposed in a common plane,

it is characterized in that the preparation method is characterized in that,

the rolling surface is partially designed as a spherical surface.

18. The device of any one of claims 1 to 12,

it is characterized in that the preparation method is characterized in that,

a cleaning module (10'') having a vacuum chamber (60) with an access opening (62) provided with a sealing element (64) is provided for the metering and dispensing device (30).

19. The apparatus of claim 18, wherein the first and second electrodes are disposed in a substantially cylindrical configuration,

it is characterized in that the preparation method is characterized in that,

the sealing element (64) has an annular projection (66).