Patent Grant
9481007
This invention relates to a system and method for the controlled and accurate application of adhesives and/or sealants to substrate materials. Specifically, this invention is directed to increasing the quality of an adhesive application process on a substrate such as a bag.
Adhesives are used in many industries to adhere one substrate to another. The effectiveness of the adhesive to bond the substrates hinges on the proper application of the adhesive during the application process. For example, the temperature of the adhesive, the amount of adhesive applied to the substrate, the consistency of the adhesive across the substrate, and the position of the adhesive applied on the substrate, all affect the quality of the adhesive bond. It is critical to meet the desired specifications for the application of the adhesive to prevent the production of defective products.
The packaging industry relies on proper adhesive application in the production of bags, such as a pinch bottom bag which is commonly used for packaging a wide variety of items such as pet food. An adhesive is applied to the bottom end of the bag along a portion of the bottom edge. The adhesive bottom edge is folded over and the adhesive seals the bottom end of the bag. An adhesive is similarly applied to the top end of the bag along a portion of the top edge. The adhesive is dried. The bags are shipped to a customer. The customer fills the bags with product, and seals the top end of the bag by heating up the pre-applied adhesive and folding the adhesive top edge over to seal the top end. If the adhesive is not properly applied to the bag ends then the bag ends will not seal properly and the product within the bags may spill out of the bag or spoil. The defective non-compliant bags increase the cost of manufacturing the bag. It also can result in costly rework, returns, and claims due to poor quality, along with other associated expenses and the potential for lost business and lost customers.
One type of adhesive dispenser used in such applications is shown in U.S. Pat. No. 6,746,712. A flow meter system is described that measures the flow of the adhesive and generates data regarding total adhesive used for the purpose of optimization. This system addresses one common problem in the industry directed to calculating and instructing the adhesive equipment to apply a calculated amount of total adhesive onto each individual bag.
However, little improvement has been done over the years to ensure proper application of the adhesive to a substrate. Thus, the industries rely on quality control checks to monitor the process. Monitoring the application of the adhesive is normally done by random sampling or visual checks during production.
The accuracy of such monitoring systems is low due to the limited capacity of the available methods used in the industry, external influences and human errors. For example, a mass flow meter is used to measure the amount of total adhesive applied to an individual bag. However, while the calculated amount of adhesive is applied to the bag, the mass flow meter or monitoring systems are not capable of verifying that the adhesive was applied evenly and consistently across the desired range on each bag. In one situation, the deposit of adhesive is too heavy at the beginning of the application process on the bag but it quickly thins out by the end of the application process on each bag. The bag would appear to be within the specifications because the total mass of the adhesive applied would be within the specification but in reality the application was not consistent across the width of the bag and the quality would be compromised.
Another problem associated with the application of adhesive is the positioning of the adhesive on the bag. The bags run through a production line and the adhesive is applied to the bag as it passes by the nozzle that dispenses the adhesive. If the bags are not properly aligned, then the adhesive would be applied on an angle, too high or too low along the edge, or there would be a void of adhesive due to a folded edge. Once the adhesive is applied to the bag there are no checks in place to verify the proper placement of the adhesive.
If the adhesive is applied inadequately to the bag, rejection of the bag is generally the result. Additionally, many processes that apply adhesives operate at high speeds which increase the number of rejected bags prior to shutting down the system to make corrections. By the time an operator recognizes and reacts to a non-compliant adhesive application the time delay is significant, resulting in increased waste of non-compliant bags. The time delay dramatically increases the economic costs associated with these rejected bags which is typically absorbed by the manufacture and results in reduced quality, reduced profits, and a reduced ability to compete.
There is a need to for a more accurate monitoring system that is able to provide a quicker response time to an error in the application of the adhesive. Additionally, there is a need to provide a monitoring system that monitors the entire process including monitoring the temperature of the adhesive prior to the application, the application of the adhesive consistently across the desire range of the substrate, and the positioning of the adhesive on each substrate at the end of the process. Additionally, there is a desire to reduce costs associated with the adhesive process including costs associated with returning and reworking non-compliant final product and reduced use of raw materials. Furthermore, there is a desire for reporting capabilities of a monitoring system for quality control purposes.
The present invention is directed to a system for regulated and controlled application of adhesive to substrates. The system includes a reservoir tank for containing a supply of adhesive, at least one applicator nozzle, conduit system for guiding the flow of adhesive from the reservoir tank to the nozzle, an application sensor located between the reservoir tank and the nozzle, a mass flow meter located between the application sensor and the nozzle; and a monitoring unit with an associated data processing program. The monitoring unit is operable to control pressure and temperature in the conduit system in response to the signals received from the mass flow meter. The monitoring unit is further operable to regulate consistent and even application of adhesive to a substrate.
The present invention is further directed to a method for regulating application of an adhesive to a substrate. The method includes the steps of inputting total target amounts of adhesive to deposit on a bag and bag dimensions into a monitoring unit. A graphical interface may be employed. The monitoring unit is employed to calculate bag area of the application of adhesive based on bag dimensions, and calculate target incremental deposits of adhesive to be applied on the bag at incremental measurements. The next step is measuring mass flow rate of an adhesive through a mass flow rate meter. The monitoring unit is used to calculate a measured incremental mass flow rate based on measurements transmitted by the mass flow rate meter and compare the measured incremental mass flow rate to the target incremental deposit to determine whether the measured incremental mass flow rate equals the target incremental deposit defining a result. The next step is to adjust the mass flow rate of the adhesive through the mass flow meter by adjustment of the pressure or temperature in response to the results.
The present invention is also directed to a method for the controlled application of adhesive to substrates including providing an adhesive application device including a reservoir tank for containing a supply of adhesive, a mass flow meter located between the tank and the nozzle, the reservoir tank and the nozzle being fluidly connected by a conduit system capable of transporting the adhesive, and a monitoring unit with an associated data processing program, the monitoring unit being operable to receive mass flow rate signals from the mass flow meter, and the monitoring unit being operable to control a pump and heating element. The next steps are employing the mass flow rate meter to measure the mass throughput of the adhesive defining measured mass flow data, and transmitting the measured mass flow data to the monitoring unit. The final steps include controlling the amount of adhesive, and controlling consistent and even application of the adhesive on the substrate at a plurality of points along the substrate by continuous monitoring the mass of adhesive to be applied and selectively adjusting the output of the pump and heating element response to the signals.
The present invention is directed to a method and system for regulating and controlling adhesive application. The system is a control system associated with an adhesive application system which applies adhesive to a substrate such as a bag. The control system performs a variety of functions including monitoring various variables in the application process, reducing defects during the application process by adjusting the process as a result of the monitoring data, and reporting monitoring results. While varieties of the present system may be used in a wide variety of industries, the system is particularly useful in formation of both ends 15, top and bottom, (15a,15b) of the pinching bottom bag process, as shown in
The steps of applying (2),(4) the adhesive 17 to the bag 11 include the use of an adhesive system 10.
Starting from the hot-melt tank 22, the adhesive 17 is delivered by an adhesive equipment 32 through a pipe system 7, which preferably comprises rigid and/or flexible pipes and may be cooled or heated, through the mass flow meter 34 to at least one applicator nozzle 42 where the adhesive 17 is applied to a substrate material or bag 11, disposed on a continuous or intermittent conveyor device 13. The adhesive equipment 32 includes various instruments (not shown), control panel (not shown) and equipment such as a heating element (not shown) and intermittent or continuous pump 27. The adhesive equipment melts the adhesive to a desired temperature, maintain the temperature of the molten adhesive and control the delivery and flow of the adhesive through the system to the application site or nozzle 42. For example, the pump 27 is used to generate pressure in the pipe system 7 to regulate flow of adhesive. While
The mass throughput of the adhesive 17 is measured by the mass flow meter 34 which is preferably positioned between the adhesive equipment 32 and the at least one applicator nozzle 42. The quantity of adhesive 17 flowing through the mass flow meter 34 is determined and transmitted to the control unit 12. The mass flow meter 34 may be regarded as part of an automatic control circuit which monitors the actual mass throughput of the adhesive 17 and signals changes to the control unit 12.
With additional reference to
The adhesive 17 starts off as pellets in a container 29 which is transferred into a hot-melt tank 22 by a vacuum feed system 30. The level and temperature of the adhesive 17 within the hot-melt tank 22 are monitored and adjusted to meet the target level and temperature to avoid viscosity issues or lack of raw material during the application process. The level component 24 includes level sensor 26, a level logic program 28, and a vacuum feed system 30 to monitor and adjust the adhesive 17 prior to use. The sensor 26 identifies the amount of adhesive 17 in the hot-melt tank 22 by measuring the level of adhesive 17 in the hot-melt tank 22. The sensor 26 sends the measured level to the logic program 28 through a transmission line 8. The logic program compares the previously programmed set-point level to the measured set-point level. If the levels are inconsistent, then the logic program 28 sends a signal through a control line 9 to the vacuum feed system 30 to draw adhesive 17 from the supplied container into the hot-melt tank 22. In reference to a low level measurement by the sensor 26, once the sensor measures the tank level at the target level, then the logic program instructs the vacuum feed system 30 to cease from drawing any further adhesive 17 to the reservoir tank 22. The temperature/level component 24 continually checks and adjusts the tank level throughout the application process.
When the adhesive 17 exits the hot-melt tank 22 and enters into the adhesive application system which directs the adhesive 17 from the hot-melt tank 22 to the bag 11. Adhesive equipment 32 measures the temperature and pressure in the adhesive system by use of sensors (not shown). The adhesive equipment verifies the target temperature of the adhesive 17 and the target pressure in the adhesive application system, such as the piping system 7, is satisfied. Additionally, the flow rate of the adhesive 17 through the system is controlled by the control unit 12 and adhesive equipment 32. If the control unit 12 determines that the flow rate of the adhesive is too slow, then the control unit 12 sends a signal to the adhesive equipment 32 through a control line 9. The adhesive equipment 32 receives the control signal and processes it to activate the pump 27 and increase the pressure in the lines 7 and increase the flow rate, and/or a signal is sent to a defective detection device 50 such as an alarm to alert the operator of a noncompliant event. Once the control unit 12 determines that the flow rate is within the target range, a signal is sent to the adhesive equipment 32 and the pump 27 is maintained or returns to the original state prior to the noncompliant event and/or a signal is sent to deactivate the alarm.
The adhesive 17 travels from the tank 22 to a mass flow meter 34. The mass flow meter 34 sends the flow rate measurements to the control unit 12 to determine if the correct amount of adhesive 17 is being applied along the designated adhesive path 35 on the bag. The control unit 12 includes a graphical interface 19 which allows for an operator to input various specifications, such as bag specifications and adhesive requirements, for the application of adhesive 17 on a series of bags. The control unit 12 can also display range limitations entered on the graphical interface 19. The control unit 12 may also display alarms and alerts on the graphical interface 19. Initially, the operator inputs information into the control unit, such as bag dimensions 14, width of adhesive strip 35 to be applied 16, the target total deposit of adhesive 17 to be applied 18 and high limit and low limit of the total target deposit 20. Additional information such as adhesive density may be pre-programmed into the control unit 12, to assist with the necessary calculations performed by the control unit 12. The control unit 12 uses this information to set the target range for this particular series of bags. For example, the control unit 12 calculates the area of the adhesive 17 needed per bag by multiplying the width of the bag (length of the adhesive strip 35) by the width of the adhesive strip 35.
The control unit 12 calculates the targeted total deposit of the adhesive 17 for each bag and the high and low limits based on the customer specifications entered into the control unit 12. Specifically, the customer enters the target deposit (D) of adhesive applied over a specific area; the target range including the minimum acceptable amount of adhesive (min) over a specific area, and the maximum acceptable amount of adhesive (max) over a specific area; the width of the bag which is the length of the adhesive path (L) and the width of the adhesive path (W). The control unit 12 calculates the target total deposit of adhesive (T) to be applied to each bag using the following equation:
T=D*L*W
Similarly, the calculated target range for each bag is calculated to determine the minimum calculated range (MN) and maximum calculated range (MX), as follows:
MN=min*L*W
MX=max*L*W
The calculated target deposits (T, MN and MX) are used to determine if the measured deposits during the application process meet the required customer standards. The calculated target deposits of adhesive 17 per bag are divided into equal target incremental deposit defining calculated target incremental deposits (ID, MNI, MXI) along each incremental distance (I) of the bag. The target incremental deposits (ID, MNI, MXI) are used to compare the measured deposits from the mass flow meter 34 delivered along each increment. The comparison is used to correct out of range errors and to verify that the adhesive 17 is being applied equally and consistently across the adhesive path. For example, the customer enters the target deposit (D) of adhesive applied over a specific area (i.e. D=0.9 grams/15 in2); the target range including the minimum acceptable amount of adhesive (min) over a specific area (min=0.7 grams/15 in2) and the maximum acceptable amount of adhesive (max) over a specific area (max=1.1 grams/15 in2); the width of the bag which is the length of the adhesive path (L) (L=30 in.) and the width of the adhesive path (W) (W=1.5 in.). The control unit 12 calculates the target total deposit of adhesive (T), the minimum calculated range (MN) and maximum calculated range (MX), as follows:
T=D*L*W=(0.9 grams/15 in2)*(30 in.)*(1.5 in.)=2.7 grams
MN=min*L*W=(0.7 grams/15 in2)*(30 in.)*(1.5 in.)=2.1 grams
MX=max*L*W=(1.1 grams/15 in2)*(30 in.)*(1.5 in.)=3.3 grams
Therefore, the target total deposit of adhesive per bag is 2.7 grams and the allowable range is between 2.1 grams and 3.3 grams. The control unit then divides these calculated amounts into equal incremental deposits (ID, MNI, MXI) along each incremental (I) distance of the bag, as shown below:
ID=T/I
MNI=MN/I
MXI=MX/I
For example, if the customer inputs the control unit will collect information from the mass flow meter at 3 points along the adhesive path per bag then the incremental value is 3 (I=3). The control unit 12 calculates and compares the application of adhesive three times along the adhesive path for each bag. Therefore, the target total deposit of adhesive per bag and the allowable range of adhesive deposit per bag is divided by the increment 3. Thus, the target incremental deposit (ID) is calculated to be 0.9 grams. The incremental allowable range is between MNI=0.7 grams to MXI=1.1 grams of adhesive. Therefore, the total target amount of adhesive applied to the bag is 2.7 grams and the adhesive is monitored by the control unit 12 at three points along the adhesive path and each point has a target incremental amount of adhesive of 0.9 grams in accordance with this example.
Based on the preprogrammed amounts, the control unit 12 calculates the amount of adhesive that must flow through the mass flow meter 34 for a specific amount of time in order to deliver an incremental deposit (ID). For example, based on the above-example, if the application of adhesive to each bag takes a total time (Tt) of 9 seconds, then 2.7 grams of adhesive must pass thorough the mass flow meter in 9 seconds to satisfy the target total deposit (T) per bag. Therefore, the incremental deposit (ID) of 0.9 grams of adhesive must pass through the mass flow meter in an incremental time (It) of 3 seconds based on an incremental value of 3 (I=3), as shown below:
Tt=It/I
The incremental deposit (ID) of 0.9 grams of adhesive is applied to each bag at three points (I=3) along the adhesive path to delivery a target total deposit (T) of adhesive of 2.7 grams per bag. The control unit 12 collects the measured mass flow rate of the adhesive 17 through the mass flow meter 34 for a specific increment of time (It) (i.e. 3 sec.). The control unit 12 receives the measured mass flow rate data and the flow logic program 38 compares the measured amount of adhesive traveling through the mass flow meter 34 for the increment of time (It) to the calculated target incremental deposit (ID). If the measured value equals the calculated value then the system is determined to be within the specification, and no adjustments are necessary and the adhesive 17 travels through nozzle 42 and is applied to a bag 11 at step (2). If the measured value is not equal to the calculated value then a signal is sent from the control unit 12 to a flow control loop 40 of the adhesive equipment 32. The flow control loop 40 adjusts the pressure in the piping system to increase or decrease the mass flow rate of the adhesive 17, such that the measured value is equal to the calculated value. The control unit 12 continuously performs comparisons to the calculated value and the target value which equates to three comparisons per bag (in this example) to verify that the total adhesive 17 applied to the bag is equally distributed across the bag at three different positions such as the lead edge, middle and trail edge. The comparisons and adjustments provide a consistent application of adhesive 17 across the bag edge. While three comparisons are discussed herein, it is contemplated that a plurality of comparisons may be performed in shorter integrals across each bag by the control system 10 to provide consistent application of the adhesive 17. Similarly, if the measured value is not equal to the target value then the control unit 12 compares the measured value to the target incremental deposits minimum (MNI) and maximum range (MXI). If the measured value is outside of the range then the control unit 12 will send a signal to adjust the pressure in the system and additionally will send a signal to alert the operator of a non-compliance using external alarms.
As shown in
The adhesive 17 is applied to the top end in the same manner as the bottom end. The control system 10 performs the same functions as above-described with the bottom end application but further includes a positioning detections device 44.
The adhesive 17 travels from the hot-melt tank 22 to the mass flow meter 34. The mass flow meter 34 transmits the measured mass flow rate data to the control unit 12 and the control unit 12 compares the calculated measured deposit amounts to the target deposit amounts. Adjustments are made as necessary and described above. The adhesive 17 travels from the mass flow meter 34 through the nozzle 42.
The control system 10 includes a variety of action plans to alert the operator of the non-conformance in the application process when the control system 10 identifies a non-conformance. The control system 10 can activate a visual alert, such as a light stack including color coded lights to indicate all clear, target not met, or out of acceptable range limits. The system 10 can also activate an audio alert, such as and alarm, buzzer, or audio instructions for the operator. Additionally, the system 10 can activate a mechanism to reject the non-conforming bag 11 and remove it from the production line. Further, the control system 10 can activate an E-stop to shut down the production line to allow the operator to make adjustments, remove non-conforming bags, or redirect the bags as needed. The control system 10 is capable to activating individual alerts or a combination of alerts.
The control system 10 of
Having described the preferred embodiments herein, it should now be appreciated that variations may be made thereto without departing from the contemplated scope of the invention. Accordingly, the preferred embodiments described herein are deemed illustrative rather than limiting, the true scope of the invention being set forth in the claims appended hereto.
This application is a continuation of International Patent Application No. PCT/US2010/061211 filed Dec. 20, 2010, which claims priority to U.S. Patent Application Ser. No. 61/288,400 filed Dec. 21, 2009, the contents of both of which are incorporated herein by reference.
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| Number | Date | Country | |
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| Child | 13528441 | US |
