阅读说明：本技术 用于确定借助活塞泵输送的体积的方法和起双重作用的能气动驱动的用于实施方法的活塞泵 (Method for determining the volume delivered by means of a piston pump and double-acting pneumatically drivable piston pump for carrying out the method ) 是由 U.默斯利 H.费利克斯 A.霍费尔 于 2019-07-24 设计创作，主要内容包括：本发明提出一种用于确定液态的介质、尤其是得到加热的粘合剂的、由起双重作用的气动驱动的活塞泵有效地输送给负载的体积V<Sub>eff</Sub>的方法。此外,本发明提出一种用于执行所述方法的活塞泵(3)。(The invention relates to a volume V for determining a liquid medium, in particular a heated adhesive, which is effectively fed to a load by a double-acting pneumatically driven piston pump eff The method of (1). The invention further relates to a piston pump (3) for carrying out the method.)

1. Method for determining the volume V of a liquid medium, in particular a heated adhesive, which is effectively delivered to a load by a double-acting pneumatically driven piston pump _effWherein the piston pump is provided with a leak, characterized in that, when a constant pressure acts on the drive of the piston pump and at least one double stroke of the piston pump is performed from one dead point to the other dead point thereof and back to one dead point:

a. measuring a leakage time t for a stroke of the piston pump from its bottom dead center to its top dead center in the event that the piston pump is unable to deliver a medium to a load _{L auf}，

b. Measuring the dead end of the piston pump when the piston pump is unable to deliver the medium to the loadLeakage time t of the stroke of a point up to its bottom dead center _{L ab}，

c. For a stroke of the piston pump from the bottom dead center to the top dead center, a volume V of the medium of the piston pump is obtained which is conveyed in a theoretically leakless manner _aufAnd the leakage time t _{L auf}The quotient between the two is,

d. for the stroke of the piston pump from the top dead center to the bottom dead center, a volume V of the piston pump which is theoretically delivered without leakage is determined _abAnd time of leakage t _{L ab}The quotient between the two is,

e. measuring the time t for the stroke of the piston pump from the bottom dead center to the top dead center when delivering a medium to a load _aufAnd measuring the time t for the stroke of the piston pump from the top dead center to the bottom dead center _ab，

f. Effectively delivered volume V _effAccording to

2. Method according to claim 1, wherein the effectively transported volume V of the transported medium with respect to its mass is determined _effAnd in accordance with

3. The method of claim 2, wherein the delivered mass of the medium is continuously calculated as the medium is delivered to the load by: the calculated volume V effectively delivered _effMultiplied by the density D.

4. Method according to one of claims 1 to 3, wherein the method steps are repeated after each change of the temperature setting of the medium to be delivered to the load and/or after each change of the liquid medium, in particular of the heated adhesive, and/or after each change of the pressure acting on the drive of the piston pump.

5. Method according to any one of claims 1 to 4, wherein the leak time t is measured automatically before starting production, in particular before starting production _{L auf}And t _{L ab}And/or total leakage time t _Leck。

6. The method according to any one of claims 1 to 5, wherein the leakage time and/or density of each media type, in particular adhesive type, is preserved and the temperature is preserved for later use when produced under comparable conditions without the need for a renewed determination.

7. Method according to any one of claims 1 to 6, wherein the leak time t for the output pressure measurement is corrected by means of a test-based calculation model upon a change in the pressure acting on the drive of the piston pump _{L auf}And t _{L ab}Or its total leakage time t _Leck。

8. Method according to one of claims 1 to 7, wherein a message, in particular relating to the wear of the piston pump, is output when a large deviation of the currently measured leak time from the saved value of the leak time is detected.

9. Method according to one of claims 1 to 8, wherein the reversal position of the piston pump and/or an intermediate position of the piston between its reversal points is detected by means of a Hall sensor.

10. The method of claim 9, wherein the effective delivered volume and/or delivered mass is calculated from knowledge of the position of the piston.

11. Double-acting pneumatically drivable piston pump (3) for carrying out the method according to one or more of claims 1 to 10, having a piston (18) which is not designed to be sealed with respect to a cylinder (19), having a piston rod (11) which is not designed to be sealed with respect to a guide (19), and having two non-return valves (20, 21), wherein one of the non-return valves (20 or 21) is open and the other non-return valve (21 or 20) is closed in the direction of movement of the piston (18).

12. Piston pump according to claim 11, wherein the check valves (20, 21) are designed differently.

Technical Field

The invention relates to a method for determining the volume of a liquid medium, in particular a heated adhesive, which is effectively delivered to a load by a double-acting pneumatically driven piston pump. The invention further relates to a dual-action, pneumatically drivable piston pump for carrying out the method.

Background

In the field of adhesive application, in particular in the field of the transport of viscous hot-melt adhesives, there is a desire to know the amount of adhesive applied as accurately as possible. It should be possible to ascertain for each product as much as possible whether the correct amount of adhesive has been applied. From which statistical information, trend displays and an assessment of whether a product is manufactured with the required quality can be derived. For many products, the amount of adhesive applied is very small, so that these conclusions cannot be applied to each individual product processed, but only to the average of a certain number of products. The following requirements arise therefrom, namely: the accuracy of the measured binder volumetric or mass flow rate should be better than about ± 7%.

A device for determining an output for obtaining a delivery volume of heated adhesive is known from WO 2016/010597 a1, wherein the device has a pneumatically driven piston pump which serves a dual function. In order to detect the delivery volume of the piston pump, a position sensor for the piston rod of the piston pump is provided. The delivered volume is thus calculated based on knowledge of the respective piston position.

An adhesive dispensing system and a method relating thereto are known from EP 2732884 a 2. The system has a diagnostic module for determining, inter alia, the volume flow delivered by the pump. Leak testing is used for testing the tightness of the pump. The pump is a pneumatically driven piston pump that serves a dual purpose.

A reciprocating piston pump with an electronically monitored air valve and piston is described in EP 1907806B 1. The pump comprises a piston and, in addition, a sensor for detecting the position of the piston.

The piston pump is a positive displacement delivery pump due to its structure. In practice, pneumatically driven piston pumps are used which have a dual action, in which a certain leakage between piston and cylinder is intentionally produced, and the guide of the piston rod adjacent to the pressure chamber of the piston pump is not designed to be sealed.

In order to be able to deliver a medium in liquid form, in particular to obtain a volume flow of heated adhesive that is as continuous as possible, the piston pump delivers the medium in both directions of travel of the piston. It is a piston pump that serves a dual purpose. To be able to achieve this, two non-return valves are provided with different designs. During the reversal process at the bottom dead center and the top dead center of the piston, during the actuation of the check valve, a slight volume flow loss occurs. This loss is not as great at top dead center as at bottom dead center. This loss depends in particular on the viscosity and the flowability of the liquid medium or of the binder used.

In order to minimize wear, avoid maintenance work and achieve as long a service life as possible, the piston of the pump is constructed in an unsealed configuration. Thus, a certain leakage is made between the piston and the cylinder. This leakage depends above all on the viscosity and flow properties of the liquid medium/liquid adhesive, the size of the annular gap around the piston and the speed of the piston movement.

Likewise, the guide of the piston rod adjacent to the pressure chamber is also designed in an unsealed manner. A certain leakage is made between the piston rod and the guide means. This leakage-volume flow is preferably conducted back into the reservoir/adhesive tank. This leakage depends above all on the viscosity and flow behavior of the liquid medium/adhesive, the size of the annular gap around the piston rod and the speed of the stroke movement, and furthermore on the consumption of the liquid medium/adhesive or how many valves of the application device are opening.

The speed of the piston is first determined by the pressure of the compressed air, which acts on the drive of the piston pump.

Generally, piston pumps have no means for detecting the position of the piston. Only in the switching position is a sensor present, which controls the drive of the piston pump and causes the switching of the stroke direction. In principle, the piston position can be detected by two hall sensors.

It is important for the user of the piston pump to know the quality of the output or of the adhesive applied for each product of the liquid medium.

Disclosure of Invention

The object of the invention is to specify a method for precisely determining the volume which is effectively delivered to a load by a double-acting pneumatically driven piston pump with leakage. The object of the invention is, furthermore, to specify a piston pump which is designed to be advantageous for carrying out the method.

This object is achieved by a method having the features of claim 1 and, in addition, by a dual-action pneumatically drivable piston pump having the features of claim 9. Improvements of the invention are the subject of the dependent claims.

The invention relates to a method for determining the volume flow V of a liquid medium, in particular a heated adhesive, which is effectively supplied to a load by a pneumatically driven dual-acting piston pump _effWherein the piston pump is provided with a leak, characterized in that, when a constant pressure acts on the drive of the piston pump and at least one double stroke of the piston pump is performed from one dead point thereof to the other dead point thereof and back to the one dead point:

a. measuring a leakage time t for a stroke of the piston pump from its bottom dead center to its top dead center in the event that the piston pump is unable to deliver a medium to a load _{L auf}，

b. Measuring a leakage time t for a stroke of the piston pump from its top dead center to its bottom dead center in the event that the piston pump is unable to deliver a medium to a load _{L ab}，

c. For a stroke of the piston pump from the bottom dead center to the top dead center, a volume V of the medium of the piston pump is obtained which is conveyed in a theoretically leakless manner _aufAnd the leakage time t _{L auf}The quotient between the two is,

d. for the stroke of the piston pump from the top dead center to the bottom dead center, a volume V of the piston pump which is theoretically delivered without leakage is determined _abAnd time of leakage t _{L ab}The quotient between the two is,

e. for the slave of the piston pump when delivering the medium to the loadMeasuring time t of travel from bottom dead center to top dead center _aufAnd measuring the time t for the stroke of the piston pump from the top dead center to the bottom dead center _ab，

f. Effectively delivered volume V _effAccording to

Multiplied by the number of double strokes.

In this method, the leakage time is therefore determined as a physical variable which can be easily determined with the same operating conditions which are then to be used for production. With regard to the use of the method in connection with heated adhesives of the adhesive type, the most important operating conditions are the adhesive temperature and the pressure of the compressed air for the drive of the piston pump.

Since the pneumatically driven double-acting piston pump has a leak, in particular the piston and the non-return valve of the pump represent a certain leak, the piston pump always moves slightly in the ready-to-operate state even without consuming the liquid medium/adhesive. In order to take all losses into account, the time is measured during which the piston pump performs one or more complete double strokes. This leak time is used together with the pressure of the air to calculate an effective leak. The advantage is that the determination of the leakage time can be obtained efficiently without having to transport the liquid medium/liquid binder and thus without losing the medium/binder. The leakage time is therefore the time which elapses until the piston pump is ready to operate and has performed one or more complete double strokes without the liquid medium/liquid adhesive being dispensed.

The leak time of the double stroke is divided into a time for the up stroke (movement of the piston from the bottom dead center to the top dead center) and a time for the down stroke (movement of the piston from the top dead center to the bottom dead center). The time for these two stroke movements is not the same. The effective volume delivered for each direction of travel can be calculated in a simple manner from these two times by means of a linear relationship.

In addition to the detection of the volume which is effectively delivered by the piston pump with leakage, it is often important in practice to know also the mass of the liquid medium which is delivered by the piston pump, in particular the mass of adhesive which is applied per product. The quality is preferably obtained in two steps. First, the volume of the liquid medium delivered per time unit, in particular the volume of the adhesive and the amount of product processed, are determined by means of the calculated leakage. In a second step, the mass is obtained with the previously obtained density of the medium/binder in liquid state. Therefore, information about leakage and density must be obtained before the mass delivered can be calculated.

It has been shown that there are two simple methods that must be performed before a calculation can be made. On the one hand, the leakage time described above should be obtained. On the other hand, the density of the liquid medium/binder should be achieved.

In particular when using liquid adhesives, the density depends on the temperature of the adhesive and the type of adhesive. The volume effectively delivered depends on the manufacturing tolerances of the piston pump and may depend on the existing wear. In order to be able to take this into account, a largely freely selectable duration which should comprise a plurality of complete stroke cycles of the piston pump delivers the adhesive and at the same time the amount is calculated according to the method described here. In order to be able to calculate the quantity in particular, the leakage time must first be measured. The delivered adhesive was collected and weighed. After the delivered mass is input, a correction factor can be determined, which is used to calibrate the calculation. This correction factor can be expressed as the density of the adhesive.

With the two measured variables, the leakage time and the correction factor for the mass calculation, the mass delivered can be calculated to ± 7% with precision.

Once production is performed with a changed temperature setting or other liquid medium/other adhesive type, two measurements of leak time and correction factor are repeated to be able to continue to comply with the desired ± 7% accuracy of the calculation.

If the air pressure of the drive for the piston pump is changed, this effect can be easily compensated for by suitable calculations. This calculation is performed empirically, among other things. Therefore, no new calibration is necessary when the air pressure of the piston pump changes.

The determined leak time and correction factor are preferably stored meaningfully in terms of adhesive type and temperature, so that they can be reused for subsequent production under comparable conditions without the need for renewed determination. The acquisition of the data field can also be carried out first and stored according to the type of adhesive, so that the user is not hampered by the alignment process during production.

In order to produce additional benefits, the wear of the piston pump can be determined in the large deviation between the currently measured leakage time and the saved value.

The measurement of the leak time can be performed automatically before production starts. The user can program the clock face times for the end and start of his production. The melting device for melting the adhesive is then switched on before the start of the predefined production in time in order to reach the operating temperature before the start of the production. The control unit can be programmed in such a way that the switching-on takes place somewhat earlier, in order to be able to automatically measure the leakage time at the operating temperature reached before the start of production. The user will then not notice this measurement process. As long as the measurement of the leak time is not completed, there is no production release for the higher-level control mechanism. The measurement of the leak time should also be able to be started manually by the operator.

If only the end position of the piston pump can be measured, the intermediate position of the piston cannot be determined accurately. As a remedy for the smaller resolution of the metered adhesive quantity, the time elapsed since the last switch can be used. Thus, the amount of adhesive delivered by the plunger and the intermediate position of the plunger can generally be interpolated with sufficient accuracy.

By measuring the position of the piston of the pump, a still greater accuracy of the determination of the amount of adhesive applied per product processed can be achieved.

In particular, it is provided that the reversal position of the piston pump and/or an intermediate position of the piston between its reversal points is detected by means of a hall sensor.

The effective delivered volume V is preferably calculated from knowledge of the position of the piston _effAnd/or the mass m delivered.

Calculating the applied mass of the adhesive in the sense described above represents a particularly simple possibility. Additional revenue can be generated for the user with little, if any, overhead consisting largely of overhead for the software. An improvement of the adhesive-coated measuring scheme can be achieved easily and with little expenditure.

In particular, it is provided that the volume V to be effectively delivered during delivery is determined _effDuring the period of time m of the transported medium and in accordance with

The density D of the medium is calculated.

Preferably, the delivered mass of the medium is continuously calculated while the medium is delivered to the load by: the volume calculated according to the above method is multiplied by the determinative density D.

In particular, the method steps are repeated after each change in the temperature setting of the medium to be fed to the load and/or after each change in the liquid medium, in particular the heated adhesive, and/or after each change in the pressure acting on the drive of the piston pump. In particular, the leak time t is measured automatically before the production begins, in particular before the production begins _{L auf}And t _{L ab}And/or total leakage time t _Leck。

In particular, the leak time and/or correction factor for each media type, in particular adhesive type, and the temperature are saved for later use in production under comparable conditions without renewed determination.

Correction for pressure changes acting on the drive of the piston pump, in particular, by means of a calculation model based on testsLeakage time t of output pressure measurement _{L auf}And t _{L ab}Or its total leakage time t _Leck。

In particular, a fault message, in particular relating to wear of the piston pump, is output when a large deviation of the currently measured leakage time from the stored value of the leakage time is detected.

The piston pump used in the method according to the invention and in a development of the method is in particular designed as a dual-action pneumatically drivable piston pump having a piston which is not designed to be sealed with respect to the cylinder, having a piston rod which is not designed to be sealed with respect to the guide means, and having two non-return valves, wherein one of the non-return valves is open and the other non-return valve is closed in the direction of movement of the piston.

The non-return valve is designed in particular differently.

Further features of the invention are indicated in the dependent claims, the description of the figures and the figures themselves, wherein it is to be noted that all individual features and all combinations of individual features are essential to the invention.

Drawings

The invention is illustrated by way of example, but not limited to, in the figures.

Fig. 1 shows an application unit for hot adhesive, having an adhesive tank and an adhesive pump mounted in the adhesive tank,

figure 2 shows in cross-section the adhesive pump shown in figure 1 together with the overflow channel,

figure 3 shows a partial region of the piston pump in the upward piston stroke,

figure 4 shows a partial region of the piston pump in a representation of the piston pump during the downward piston stroke,

fig. 5 shows a diagram for explaining the leakage behavior (leakvolumes dependent on the stroke time) of a pneumatically driven piston pump which has a dual action when the piston moves from bottom dead center into top dead center and when it moves from top dead center into bottom dead center,

fig. 6 shows a diagram for illustrating the measured leakage times as a function of the pressure acting on the drive of the piston pump, which is shown for different viscosities of the heated adhesive and thus of the liquid medium, wherein the curve is calculated from the measured points.

Detailed Description

Fig. 1 shows an adhesive tank 1 for receiving, for example, EVA-based, viscous hot melt adhesives (schmelzklebstuffs), the heating element 2 of the adhesive tank 1 serves to heat the adhesive, melt it and bring it to its processing temperature (verarbeitungsten), the piston pump 3 is inserted into the adhesive tank 1 and is fixed to it, the piston pump 3 is a pump which serves a dual function and therefore acts in both stroke directions (wrksame) of the piston pump, the piston pump 3 is driven pneumatically, an orifice plate 4 is arranged in the inflow region of the adhesive from the adhesive tank 1 to the piston pump 3, said orifice plate serves to trap (Zur ü ckhaldung) the incompletely melted adhesive in the solid state, the adhesive reaches a suction chamber 5 for the adhesive below the piston pump 3 through the orifices of the orifice plate 4, from there the adhesive is sucked into the piston pump 3 and is discharged under pressure through a pressure connection 6, the adhesive reaches a distributor 8 for the adhesive load downstream of the pressure connection 6, and the adhesive reaches a distributor 8.

Fig. 2 shows the structure of the piston pump 3. The piston pump has an upper pneumatic part with a piston 10 for a drive device. The piston 10 is fixedly connected to a piston rod 11, which represents an active element for delivering the adhesive under pressure. This pneumatic region of the piston pump 3 furthermore has a pressure distributor 36 for the pneumatic system for driving the pump, a manually adjustable pressure regulator 12, a pressure gauge (Manometer) 13, a solenoid valve 14, a ring magnet 38 and a pressure sensor 39. The pressure sensor 39 is used to measure the air pressure P acting on the drive of the piston pump 3. A pressure sensor 39 is mounted behind the pressure regulator 12. The pressure sensor 39 is required in the automatic correction calculation when the air pressure P changes. The two hall sensors 16, 17 are used to determine the piston position of the piston in the reversal point and its intermediate position. By means of the piston position, the delivered volume and the delivered mass of the piston pump can be calculated for increasing the accuracy or resolution of the calculation.

The electronics of the piston pump 3 furthermore have processor-free printed electronics (Elektronikprint) 15.

The piston 18 is provided with an axial passage (durchgan) 28, in the region of which a non-return valve 20 with an associated valve seat is arranged, in addition, a through-opening 30 for the adhesive is provided in the transition region of the piston 18 to the region of the piston rod 11 with a reduced diameter, the piston 18 is not guided in a sealed manner in a housing 19 or a cylinder bore 22 formed in the adhesive delivery region, the piston pump 3 furthermore has an upper non-return valve 20 and a lower non-return valve 21, the lower non-return valve 21 is assigned to the suction chamber 5, so that the adhesive from the suction chamber 5 can pass from the side of the non-return valve 21 into the adhesive delivery chamber of the piston pump 3 when the non-return valve 21 is in the defined position, and can pass from the side of the non-return valve 20 to an outlet 356 for the adhesive (Abg 25) and from there to a pressure connection 359 for the adhesive load, if the upper non-return valve 20 is in the defined position.

A dynamic seal 33 without a pressure difference is arranged between the pneumatic element of the piston pump 3 and the adhesive supply.

Fig. 3 shows the situation when the piston 10 is transferred from the bottom dead center to the top dead center, because of the force-and-flow relationship (Strömungsverhältnisse), the ball 23 of the lower check valve 21 is lifted from the ball seat and the ball 24 of the other check valve 20 is in contact with the ball seat associated with this ball 24, as a result of which adhesive can be sucked in accordance with arrow 25 from the adhesive tank 1 and through the check valve 21 in the open position into the cylinder chamber of the adhesive supply region of the piston pump 3, while, as a result of the upward stroke movement of the piston 18, adhesive can be discharged in accordance with arrow 35 through the laterally arranged pressure channel 34 and the pressure connection 6 connected to this pressure channel in the flow direction, in this upward movement of the piston 18, a leakage flow in accordance with arrow 26 occurs in the annular gap between the piston 18 and the housing 19 due to the unsealed arrangement of the piston 18 and with the cooperating wall in the region of the piston 22, in addition, in the outflow region of the adhesive, a leakage flow occurs between the piston rod 11 and the housing 19, in accordance with the arrow 27, back into the overflow channel 29, and overflow channel 31, connected to the overflow channel 29, and overflow channel 29, which overflow of the piston rod 11, which is created.

Thus, during the stroke of the piston rod 11 and thus of the pistons 10 and 18 from the bottom dead center to the top dead center, adhesive is simultaneously delivered to the outlet 9 and is sucked from the adhesive tank 1. Leakage losses occur between the piston rod 11 and the housing 19 and between the piston 18 and the housing 19.

Fig. 4 shows the situation when the piston rod 11 is moved in the opposite direction, thus when the piston rod 11 and thus the pistons 10 and 18 are moved from the top dead center to the bottom dead center. Here only the adhesive is delivered. The adhesive is not sucked from the adhesive tank 1. The adhesive flows according to arrow 37 up through the passage 28 of the piston 18, through the through-hole 30 into the annular space between the piston rod 11 and the housing 19 and from there through the pressure channel 34 according to arrow 35 to the outlet 9. Only leakage losses occur between the piston rod 11 and the housing 19. The flow between the piston 18 and the housing 19 has no effect on the amount of adhesive delivered.

In detail, in such a top-down movement of the piston rod 11, the ball 23 comes into contact with the ball seat in its lower position, whereby no inflow from the adhesive tank 1 is possible. The adhesive flows up on the piston 18 inside. The ball 24 of the upper check valve 20 is lifted from the ball seat (aneben), whereby the adhesive is delivered to the pressure connection 6 through the through hole 30. A leakage according to arrow 27 occurs between piston rod 11 and housing 19, and thus between the pressure chamber and space 31, in which there is ambient pressure.

The screw plug is indicated with reference numeral 32.

After each change of temperature setting and after each change of adhesive, the following procedure is repeated according to the preferred method. The following process is carried out with a constant pressure acting on the pneumatic drive of the piston pump.

1. In the case where the piston pump cannot supply the adhesive to the load, the time t for a complete stroke of the piston pump from the bottom dead center to the top dead center is measured _{L auf}. The time t _{L auf}Referred to as the leak time of the upward movement of the piston.

2. In the case where the piston pump cannot supply the adhesive to the load, the time t for a complete stroke of the piston pump from the top dead center to the bottom dead center is measured _{L ab}. This time t _{L ab}Referred to as the leak time of the downward movement of the piston.

3. Total leakage time t for a complete double stroke of the piston _LeckBy two leak times t for upstroke and downstroke _{L auf}And t _{L ab}To be obtained by addition of (a).

4. For the upstroke, the ratio m between the volume delivered and the time for a complete stroke movement from the bottom dead center to the top dead center is determined _auf. For this purpose, the volume V to be transported in a theoretically leak-free manner _aufDivided by the leakage time t _{L auf}。

5. For the lower stroke, the ratio m between the volume delivered and the time for a complete stroke movement from the top dead center to the bottom dead center is determined _ab. For this purpose, the volume V to be transported in a theoretically leak-free manner _abDivided by the leakage time t _{L ab}。

6. During operation, and therefore during the supply of the medium to the load, the time elapsed is measured for each complete stroke movement of the piston pump. Determining the time t for a stroke from the bottom dead center to the top dead center _auf. Determining the time t for a stroke from the top dead center to the bottom dead center _ab。

7. Calculating the effective delivered volume V _effThe method comprises the following steps: for each ascending stroke, the theoretical volume V to be delivered _aufMinus the ratio m _aufMultiplied by time t _aufAnd for each lower lift from the theoretical delivery volume V _abMinus the ratio m _abMultiplied by time t _ab。

8. The adhesive is delivered for any duration t and collected in a collection container. During this time period t, the effective delivered volume V of adhesive is calculated according to the method described above _eff. The mass m of the collected adhesive was measured on a balance. From which the mass m delivered is divided by the volume V effectively delivered _effThe density D is determined.

9. Continuously calculating the mass delivered during operation of the piston pump by: volume V to be calculated according to the above method _effMultiplied by the density D.

The values obtained from the calibration process can be stored in a data matrix regarding the temperature setting, the adhesive type and the adhesive viscosity so that no new calibration process has to be carried out after each change.

Fig. 5 shows how the leak time for the double stroke is divided into the time for the upward stroke and the time for the downward stroke for the piston pump used. The time for the two stroke movements is not the same. The effective volume to be delivered can be calculated in a simple manner for each stroke direction by a linear relationship with these two times. Fig. 5 shows the measurement points in the upward movement of the piston in the more steep curve on the left. For a movement from bottom dead center to top dead center, the piston takes about 5 seconds and the leakage volume exceeds about 40 units. For the movement from top dead center to bottom dead center, a much longer time, i.e. nearly 30 seconds, is required, as indicated by the measuring points extending along the less inclined line.

Fig. 6 shows various curves for measurements made when using adhesives of different viscosities, where each curve represents one viscosity. The lowermost curve indicates the case of minimum viscosity, and correspondingly the curve above this curve indicates a higher viscosity adhesive. For each curve, the leakage time in seconds is shown as a function of the pressure P acting on the piston of the drive. The points shown in fig. 6 were measured and the curve was calculated.

Taking into account the above-mentioned numbers 1 to 9, it is possible to use (anwenden) calculation models when the pressure P acting on the drive of the piston pump changes. The calculation compensates for the effect of the pressure P on the amount of adhesive delivered. For this purpose, the measured leakage time t is measured _{L auf}And t _{L ab}And (6) carrying out correction. The new corrected leakage time is again used as an input value for the above-described calculation method. The calculation model can be developed by means of a large number of tests and is suitable for a specific piston pump. For other pumps, other specific values apply.

Thus, the quality of the adhesive is obtained in two steps. First, the volume of adhesive delivered per time unit and the quantity of product processed are obtained by means of the calculated leakage. In a second step, the mass is obtained with the first obtained density of the binder. Thus, before the delivered mass can be calculated, information about the leakage and about the density must be obtained. According to this way of handling, the user is able to know the quality of the adhesive applied for each product.

List of reference numerals

1 adhesive pot

2 heating element

3-piston pump

4-hole plate

5 suction chamber

6 pressure joint

7 adhesive filter

8 pressure distributor

9 outlet

10 piston

11 piston rod

12 pressure regulator

13 pressure gauge

14 spiral tube valve

15 printed electronic device

16 Hall sensor

17 Hall sensor

18 piston

19 casing

20 stop check valve

21 lower check valve

22 cylinder hole

23 sphere

24 sphere

25 arrow head

26 arrow head

27 arrow head

28 channel

29 overflow channel

30 straight through hole

31 space

32 spiral plug

33 dynamic seal

34 pressure channel

35 arrow head

36 pressure distributor

37 arrow head

38 ring magnet

39 pressure sensor