Apparatus for applying a liquid material and method for determining a function used to operate the apparatus - Patents.com

Abstract

The present invention relates to an apparatus (1) for applying a liquid material to a plurality of parts (100), comprising at least a first gun (30a) capable of applying the material to the parts (100), a reservoir (40) for holding the material, the reservoir (40) being fluidly connected to the first gun (40a), a pressure system (50) for providing a gas pressure acting on the material in the reservoir (40), the pressure system (50) having a pressure regulator (51) capable of adjusting the gas pressure acting on the material and a pressure sensor (52) for detecting the gas pressure acting on the material, a temperature sensor (70) for detecting the temperature of the material, and a control unit (60) in which a material-specific function is stored, specifying a set point for the gas pressure depending on the detected temperature of the material. The present invention also relates to a method for determining the material-specific function.

Description

[Technical field]

[0001] The present invention relates to an apparatus for applying a liquid material to a plurality of parts, the apparatus including a first material gun capable of applying material to the parts. Additionally, the present invention includes a method for determining a material specific function for use in operating the apparatus. [Background technology]

[0002] From WO2019 / 120919 such an apparatus is known having eight material guns with a reservoir for containing a liquid material. A gas pressure is provided by a pressure system and acts on the substance contained in the reservoir. The eight guns (material guns) are mounted around a rotatable gun carrier, which is mounted rotatably about a vertical main axis of rotation. Each of the eight guns is connected to a reservoir by a conduit, through which the material under gas pressure can pass from the reservoir to the gun. During operation of the apparatus, the gun carrier rotates at high speed about the main axis of rotation and parts in the form of can lids for beverage cans, on which the liquid material is applied as a sealant, are supplied to the apparatus in large quantities per unit of time. The material from the reservoir is applied to the individual can lids via the guns while the gun carrier rotates. New can lids are continuously supplied to the apparatus and can lids coated with the material are continuously discharged. Summary of the Invention [Problem to be solved by the invention]

[0003] An electromagnetic flow meter is arranged between the reservoir and each gun. The flow meter is attached to the gun carrier and therefore rotates with the gun carrier about the main axis of rotation. The flow meter detects the flow rate delivered to each gun. By using the flow meter, it is intended that a constant film weight per part is obtained. On the one hand, this means that only the required amount of material is used. On the other hand, the application amount or film weight per part must also not be too small, otherwise the intended effect of the material would not be ensured.

[0004] The effort required to obtain a constant application volume or a constant application weight with an individual flow meter is relatively large. A flow meter must be provided for each gun, which complicates the structure of the device. The flow meter must be designed so that the centrifugal forces acting during the rotation of the gun carrier do not adversely affect its functionality.

[0005] In the case of devices for applying liquid materials without the above-mentioned flowmeter, the application amount can be monitored according to a simple method described in WO2019 / 120919 and known from other prior art. In this case, during operation of the device, individual parts to which material has been applied are randomly selected. For these parts, the application amount is determined by measurement. Between the random samples, which may be several hours apart, the device operates from start to finish without any control of the application amount. There is therefore a risk that between two random samples, the application weight may change unnoticed, for example due to the external environment, rendering the coated parts unusable during this time. Furthermore, if a random sample shows that the application amount is outside the defined tolerance range, ongoing operation of some devices known from the prior art must be interrupted and appropriate readjustments must be made to the device.

[0006] SUMMARY OF THE PRESENT DISCLOSURE It is therefore an object of the present invention to provide an apparatus for applying a liquid material to a number of parts which is of simple construction, operates reliably and operates as uninterruptedly as possible. [Means for solving the problem]

[0007] This object is solved by a device according to claim 1. Example embodiments of the invention can be taken from the dependent claims of claim 1.

[0008] According to the invention, the pressure system of the device comprises a pressure regulator, by means of which the gas pressure acting on the material can be regulated. Furthermore, the pressure system comprises a pressure sensor for detecting the gas pressure. The device comprises a temperature sensor for detecting the temperature of the material and a control unit. The control unit is stored with a material-specific function that specifies a setpoint value for the gas pressure, at which the gas pressure depends on the detected temperature. Based on the setpoint value, the control unit can calculate a signal for controlling or activating the pressure regulator. Depending on the temperature detected during operation of the device, the gas pressure acting on the material may be increased or decreased. Compressed air may be used to generate the gas pressure. This means that air can be used as gas.

[0009] By varying the gas pressure, the flow through the material gun (gun) can be influenced. The invention is based on the finding that, in particular for water-based sealants such as Darex WBC4721, a product of Henkel, which can be used as application material, the temperature of the sealant affects its viscosity, which in turn affects the flow rate through the gun of the device. Thus, when using a material whose viscosity increases with decreasing temperature, the decrease in flow rate (coating amount or film weight) can be mitigated or completely compensated for by increasing the gas pressure when the temperature is decreased. The invention allows the flow rate to remain constant or nearly constant even if the temperature of the material varies. The temperature of the material may vary throughout the day. For example, the air temperature may be higher at midday than in the morning or evening due to strong solar radiation. The invention allows to avoid the need to readjust individual guns when the temperature changes (for example, if the gun is equipped with a nozzle, to change the nozzle cross-sectional area of ​​the nozzle by axially moving the nozzle needle) in order to adjust the flow resistance or flow cross-sectional area in the nozzle to the changed conditions.

[0010] In one embodiment of the present invention, more than 100 parts and guns can be coated with liquid material, for example liquid sealant, per minute. This is therefore high speed application, or mass production with very high throughput. The time it takes to coat one part is only a moment. According to a preferred embodiment of the present invention, if the device is equipped with one or more guns, for example eight guns, more than 1000 parts, even more than 1500 parts, can be coated with liquid material per minute.

[0011] In one embodiment, the function is monotonically decreasing. As the temperature increases, the gas pressure set point decreases. Such a function can be used to maintain constant film weight per part for liquid materials whose viscosity decreases with increasing temperature or increases with decreasing temperature. Depending on the flow resistance through the gun or through the conduit system between the reservoir and the gun, an increase in viscosity increases the flow resistance and increases the gas pressure. Preferably, the gas pressure set point is determined such that the coating weight (or film weight portion) remains constant.

[0012] The function depends on the material being applied by the device. For example, if the viscosity of the material decreases significantly with increasing temperature, then if the device provides a constant application speed (constant flow rate through the gun) at different temperatures, then the function of gas pressure set point will have a significant negative slope. Thus, different functions may be stored in the control unit for different materials. For example, if material A is being applied by the device, the operation of the device will require the function f stored for material A. A should be used.

[0013] The function may be a straight line with a constant slope. Alternatively, the function may also have an asymptotic or other formed path. The function is intended to identify only one gas pressure setpoint for each detected temperature value. The function does not necessarily have to be a functional equation stored or programmed in the control unit. The function may also be a table of pairs of values ​​(temperature, gas pressure setpoint). If, during operation of the device, the detected temperature is between two temperature values ​​of an adjacent pair of values, the control unit may also determine the corresponding setpoint by weighted interpolation of the corresponding setpoints. The function may therefore simply be understood as a stored or programmed calculation criterion, where given a temperature value, the gas pressure setpoint is just determined. Preferably, the control unit is in the form of a programmable logic controller (PLC).

[0014] In one embodiment, the temperature sensor is located in the reservoir. In this way, the temperature of the material in the reservoir is measured. The temperature sensor can alternatively be located as close as possible to the first gun or even in the gun. If the temperature sensor is located in the reservoir, the temperature of the material can only be measured once in the middle of the reservoir, even if the device comprises several guns. This simplifies the design of the device according to the invention.

[0015] Preferably, the control unit calculates a difference from the setpoint gas pressure and the detected gas pressure (actual gas pressure). This difference can be used to calculate or determine a signal that can activate a pressure regulator. Preferably, this is an electrical signal that can be provided by the control unit as an output signal to the pressure regulator.

[0016] At least a second gun may be provided, the reservoir being in fluid communication with the first gun as well as the second gun.

[0017] In one embodiment, the first and second guns are connected to a gun carrier which is mounted rotatably about a main axis of rotation. Preferably, the main axis of rotation extends in a vertical direction. The gun carrier may have a substantially rotationally symmetric shape and may have a holding arm for each gun around its periphery. The guns are preferably evenly distributed around the periphery of the gun carrier. For example, in the case of eight guns, the angular distance between two adjacent guns in the circumferential direction is 45°.

[0018] In one embodiment, the reservoir or at least a first portion of the reservoir is fixed and does not rotate with the gun carrier. In this case, the reservoir is rotatably connected to the gun carrier. The gun carrier may house a second portion of the reservoir, in which case the second portion of the reservoir rotates with the gun carrier. A pressure-tight connection may be provided between the first fixed portion of the reservoir and the rotatable second portion, allowing relative rotational movement between the first and second portions of the reservoir.

[0019] The gun carrier may be non-rotatably connected to a rotating plate which rotates together with the gun carrier about a main axis of rotation. The rotating plate comprises a part carrier and at least a second part carrier, the first part carrier being associated with a first gun and the second part carrier being associated with a second gun. The first part carrier and the second part carrier may each be mounted rotatably about a respective axis of rotation. The respective axes of rotation may be parallel to the main axis of rotation. Preferably, the distance between the axes of rotation of the first part carrier corresponds to the distance between the axis of rotation of the second part carrier and the main axis of rotation. In operation of the device with rotating gun carrier / rotating plate, the part carrier (also referred to as chuck) can rotate about its own axis to apply liquid material in multiple revolutions (e.g. 2-3 revolutions) of the parts.

[0020] A further problem inherent to the invention, namely to provide a method by which a material-specific function for a control unit of the above-mentioned device can be determined simply and with sufficient accuracy, is solved by claim 9. Examples of embodiments of the invention can be taken from the dependent claims of claim 9.

[0021] According to the present invention, different temperatures of the material are predetermined via a heating unit. The gas pressure is adjusted depending on the predetermined temperature so that the application amount dispensed through the first gun is the same for each of the different temperatures. A function is determined based on the adjusted gas pressure and the predetermined temperature.

[0022] The heating unit may thus be used to set a first temperature, which may represent the lower limit of the temperature range in which the temperature of the material is expected during operation of the device. Furthermore, a target film weight per part is set to the amount at which the part should be coated. At this first temperature, the gas pressure is adjusted so that the first gun (or a gun identical in structure to the gun of the device) applies the target applied film weight. The gas pressure may be adjusted manually via a pressure regulator. Thus, a first pair of values ​​is obtained, which includes the first temperature and the gas pressure (first gas pressure) associated with the first temperature. A second temperature is set after determining the first pair of values ​​of the material by the heating unit, which may supply different amounts of heat to the material via the regulating means or dissipate different amounts of heat from the material, the second temperature being, for example, 3 to 5° higher than the first temperature. As the viscosity of the material changes when the temperature changes, and therefore also the flow resistance through the first gun, the gas pressure is (manually) readjusted to achieve the target film weight again. This creates a second pair of values ​​(second temperature / second gas pressure). In this way, further pairs of values ​​can be determined by further increasing the temperature and adjusting the corresponding gas pressure to obtain the same target membrane weight in each case.

[0023] The pair of values ​​can be used in the next step of the regression analysis to determine a regression line or, more generally, a regression function. The regression line F=m*T+a function has a coordinate intercept a (nominal value of the gas pressure at a temperature of 0°) and a slope m. Exemplary values ​​of the coordinate intercept lie in the range between 20 and 25 psi. Exemplary values ​​of the slope m lie in the range between -0.1 and -0.2 psi / °C. At this point, it should be emphasized that the values ​​a, m depend on the material applied from the first gun. Different values ​​of m, a will result for different materials. The function thus determined can finally be implemented in the control unit, for example by a programming process.

[0024] The heating unit may comprise a double tube with an inner tube and an outer tube surrounding the inner tube, the inner tube passing the material through the first gun and the outer tube passing a heat medium that heats or cools the material. The heat medium may be water. The double tube provides a simple means of bringing the material to the desired temperature before entering the first gun. By using the double tube, time-consuming temperature adjustment (tempering) of the material in the reservoir can be avoided. It should be noted here that the method according to the invention does not necessarily require the entire device to be used. It is sufficient that only the gun or a gun of the same construction is used, whereby the temperature of the material upstream of the gun can be adjusted by the heating unit. Without being bound by this theory, it is considered that the possible difference between the temperature of the material in the reservoir during operation of the device and the temperature of the material downstream of the heating unit during the method of determining the function is negligibly small. The method according to the invention therefore provides a simple way of determining with sufficient accuracy the function of the setpoint of the gas pressure as a function of the temperature measured in the reservoir in an embodiment of the device according to the invention.

[0025] When determining the function, the temperature of the material can be detected between the double pipe and the first gun. It is easy to arrange a corresponding temperature sensor upstream from the first gun. As already mentioned above, any difference between the temperature of the material just before the gun and the temperature in the reservoir of the device can be ignored to a good approximation. [Brief description of the drawings]

[0026] The invention will now be explained in more detail with reference to the embodiments shown in the drawings. [Figure 1] In FIG. 1, an apparatus for applying a liquid material is shown. [Diagram 2] FIG. 2 shows the control circuitry of the device of FIG. [Diagram 3] FIG. 3 shows a schematic system for determining the function of the control unit of the device of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] 1 shows diagrammatically an apparatus 1 for applying a liquid material to a plurality of parts 100 (in this case in the form of round metal can lids, e.g. for food cans, beverage cans or beer cans). The apparatus 1 comprises a gun carrier 10 mounted for rotation about a main rotation axis 2. A rotating plate 20, which accommodates the parts 100, is non-rotatably connected to the gun carrier 10. The gun carrier 10 and the rotating plate 20 therefore form a group which is rotatable about the main rotation axis 1.

[0028] The gun carrier 10, which is preferably substantially rotationally symmetrical, has holding arms 11 for a first gun 30a and a second gun 30b, respectively. The first gun 30a and the second gun 30b are intended to denote a plurality of guns uniformly distributed around the circumference of the gun carrier 10. The gun 30a is associated with a first part carrier 21a, which is mounted rotatably about its own axis of rotation 3. The gun 30b is associated with a second part carrier 21b, which is rotatable about its own axis of rotation. During operation of the device 1, the assembly of the gun carrier 10 and the rotating plate 20 rotates about the main axis of rotation 2. At the same time, the part carriers 21a, 21b and the parts 100 arranged thereon rotate about their respective axes of rotation 3. During rotation about the main axis of rotation 2, uncoated parts are continuously fed to the device 1 and coated parts are continuously discharged.

[0029] Not shown in Figure 1 are counter pads that press components 100 against each component carrier. Proximity sensors can be provided below the counter pads for detection of components 100. If the proximity sensor indicates the presence of a component, each gun 30a, 30b receives an open signal that opens a nozzle in the gun. In the absence of an open signal, the guns 30a, 30b remain closed.

[0030] The apparatus 1 includes a reservoir 40 in which the material to be applied is stored. In the embodiment shown, the reservoir 40 rotates with the gun carrier 10. A reservoir connection 41 is provided between the reservoir 40 and the gun carrier 10, connecting the reservoir 40 to the gun carrier 10. From the reservoir 40, the material is delivered via pressure lines 12 to the individual guns 30a, 30b.

[0031] The pressure system 50 of the apparatus 1 ensures that the material in the reservoir 40 is under a constant gas or air pressure. The pressure system 50 includes a pressure regulator 51 and a pressure sensor or pressure gauge 52 that measures the pressure in a pressure conduit 53 between the pressure regulator 50 and the reservoir 40. The pressure regulator 51 is supplied with compressed air 4 from a compressed air system, not shown. The pressure regulator 51 and the pressure sensor 52 may be part of a single device.

[0032] The apparatus 1 further comprises a control unit 60 connected to the pressure regulator 51 via a signal line 61. Furthermore, a signal line 62 is provided between the pressure sensor or pressure gauge 52 and the control unit 60. A signal line 63 connects the control unit 60 to a temperature sensor 70 arranged in the reservoir 40. The temperature sensor 70 measures the temperature of the material located in the reservoir 40.

[0033] The task of the control unit 60 will be explained with reference to FIG. 2. FIG. 2 shows the set pressure p DDuring operation of the device 1, the control unit 60 receives a signal or measured temperature value T from the temperature sensor 70. A function f(T), stored in the control unit (see transmission block 65), converts the measured temperature T into a setpoint value p of the gas / air pressure. D Then, the control unit 60 converts this set value p D (Desired pressure) Measured pressure p R (actual pressure) and calculates the difference Δp between these two pressure values. The control unit 60 determines a signal from the pressure difference Δp (see transmission block 64) and transmits this to the pressure regulator 51. In the control circuit of FIG. 2, the pressure regulator 51 is 1 where the conversion block 51 is represented by 1 converts the signal received from the control unit into a pressure value.

[0034] A method for determining the function f(T) stored or programmed in a control unit according to the invention will now be described with reference to figure 3. Components similar or identical to those in figure 1 are provided with the same reference symbols.

[0035] The heating unit 80 may include a double tube 81 (shown here only diagrammatically) having an inner tube and an outer tube surrounding the inner tube. The inner tube is connected to or forms part of the conduit 12, and material from a reservoir 90 passes through the conduit 12 and the inner tube towards a first gun 30a. The gun 30a is the gun of the apparatus 1, or at least a gun of the same construction.

[0036] A heat transfer medium, preferably heated water, flows through the outer tube. The water heats and, if cooling water is used, cools the material flowing through the inner tube of the heating unit. Arrow 82 indicates the water entering the outer tube. Arrow 83 indicates the water leaving. Here, a temperature sensor 71, located between the heating unit 80 and the first gun 30a, allows the temperature of the material before it enters the gun 30a to be measured.

[0037] Reservoir 90 may be a different reservoir than reservoir 40 of device 1. However, reservoir 90 may be or represent an assembly of reservoir 40 of device 1 and gun carrier 10.

[0038] The material is heated (or cooled) to a certain temperature, depending on the amount and temperature of the inflowing water 82. In the method of the invention, when determining the function f(T), a certain target film weight is predefined, which expediently corresponds to the film weight with which the part 100 should be coated by the device 1. Given the temperature and the predefined target film weight or application amount, the adjusting means 5, which may be a manual actuator, is used to adjust the pressure regulator so as to obtain the desired target application amount at the gun 30a. The temperature and the adjusted gas pressure detected by the pressure sensor constitute a first pair of values ​​I. By changing the parameters of the inflowing water 82, the material can be brought to further different temperatures. In each case, the gas pressure must be readjusted so that the specified target film weight is obtained again. Thus, further pairs of values ​​II to VI (any number of pairs is possible) can be formed, from which the function f(T) can be calculated by regression analysis. This function f(T) is only valid for a specific material and can be stored in the control unit 60 of the device 1. For another material having different properties, especially with respect to temperature dependent viscosity, the above procedure must be carried out again. [Explanation of symbols]

[0039] 1 device 2 Main Rotating Axis 3 Rotation Axis 4. Compressed Air 10 Gun Carrier 11 Holding Arm 12 Conduit 20 Rotating Plate 21 component carrier (21a first component carrier, 21b second component carrier) 30 Gun (30a 1st Gun, 30b 2nd Gun) 40 Reservoir 41 Reservoir connection 50 Pressure System 51 Pressure Regulator 51 1 Conversion block for pressure regulator 51 52 Pressure Sensor / Pressure Gauge 53 Pressure Conduit 54 Adjustment means 60 Control Unit 61 Signal Line 62 Signal Line 63 Signal Line 64 conversion blocks 65 Conversion Blocks 70 Temperature Sensor 71 Temperature Sensor 80 Heating Unit 81d double tube 82 Inflow water 83 Runoff 90 Reservoir 100 parts

Claims

1. An apparatus (1) for applying a liquid material to multiple parts (100), The material can be applied to the part (100) using at least a first gun (30a), A reservoir (40) holds the material and is fluidly connected to the first gun (40a), A pressure system (50) that provides gas pressure acting on the material located in the reservoir (40), the pressure system (50) comprising a pressure regulator (51) on which the gas pressure acting on the material can be adjusted and a pressure sensor (52) for detecting the gas pressure acting on the material, A temperature sensor (70) for detecting the temperature of the material, A control unit (60) stores a material-specific function that identifies a set value for the gas pressure that depends on the detected temperature of the material, and Device (1) provided.

2. The function outputs a set value that decreases as the temperature increases. The apparatus (1) according to claim 1.

3. The aforementioned function is a straight line. The apparatus (1) according to claim 1 or 2.

4. The temperature sensor (70) is located inside the reservoir (40) and detects the temperature of the material located inside the reservoir (40). The apparatus (1) according to claim 1 or 2.

5. The control unit (60) determines a signal from the difference between the set value and the detected gas pressure, and the pressure regulator (51) can be activated by the signal. The apparatus (1) according to claim 1 or 2.

6. At least a second gun (30b) is provided, and the reservoir (40) is fluidly connected to the second gun (30b). The apparatus (1) according to claim 1 or 2.

7. The first gun (30a) and the second gun (30b) are connected to a gun carrier (10) that is rotatably mounted around the main rotation axis 2. The apparatus (1) according to claim 6.

8. The reservoir (40) or at least a portion of the reservoir (40) is fixed to and rotatably connected to the gun carrier (10). The apparatus (1) according to claim 7.

9. The gun carrier (10) is connected in a manner that it is rotatably fixed to a rotating plate (20) having a first component carrier (21) and at least one second component carrier (21), the first component carrier (21) being assigned to the first gun (30a), the second component carrier (21) being assigned to the second gun (30b), and the first component carrier (21a) and the second component carrier (21b) are each mounted so as to be rotatable about their respective axes of rotation (3). The apparatus (1) according to claim 7.

10. A method for determining the material-specific function of the control unit (60) of the apparatus (1) according to claim 1 or 2, A method wherein different temperatures of the material are predetermined via a heating unit (80), the gas pressure which depends on the predetermined temperature is set such that the film weight per component released by the first gun (30a) is the same for the different temperatures in each case, and the function is determined based on the set gas pressure and the predetermined temperature.

11. The heating unit (80) comprises a double tube having an inner tube and an outer tube surrounding the inner tube, through which the material passes through the first gun (30a) and through which a heat transfer medium for heating or cooling the material passes. The method according to claim 10.

12. The temperature between the double tube (81) and the first gun is detected. The method according to claim 11.

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