Patent Publication Number: US-6342264-B1

Title: Method and apparatus for dispensing material onto substrates

Description:
FIELD OF INVENTION 
     This invention relates to dispensing and dispensing systems for applying materials to substrates. In particular, this invention relates to the dispensing of adhesives, sealants, caulks, fluxes, encapsulants, and paints. This invention is especially suited to those dispensing applications which require assurance that the material has been deposited onto the substrate and which includes a means for having redundant dispensing so that production may continue in the event of a failure. 
     BACKGROUND OF THE INVENTION 
     Applying a liquid material, in particular, an adhesive, by means of an applicator to a substrate in a controlled manner is well known. Applicators, otherwise known as dispensers, guns, or valves, particularly to apply materials to a substrate for adhesion (adhesives, fluxes, etc.) and sealing (paints, encapsulants, etc.). It is also known to provide detection systems (ultraviolet, infrared, vision, etc.) to determine if the material has properly been dispensed. If the material has not been properly dispensed, the substrate may be rejected and/or the line shut down. However, in many applications, failure to properly apply the material to the substrate may cause damage to the substrate and/or cause the substrate or its contents to interfere with the line thereby causing unnecessary down time. For example, in the packaging of beverages, the failure to properly seal the case or carton, may result in the cans spilling from the container onto the conveyor and/or the production floor. The cans may rupture, thereby spilling their contents or may jam the conveying system or otherwise interfere with the transportation of other properly sealed containers. This results in unnecessary down time in cleaning up this accident. 
     Accordingly, there is a need to provide dispensing systems which not only accurately apply material to a substrate, but in the event of a failure, provide a means for maintaining production, until the failure of the dispenser may be rectified at the scheduled down time of the line thereby maintaining production. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a method and apparatus for dispensing material onto a substrate wherein upon the failure of a dispenser, another dispenser will automatically perform the function of the failed dispenser. This has the advantage of maintaining production until the failed dispenser may be serviced at a more convenient time, such as at the end of a normal production shift. This may be accomplished, by utilizing a standby or secondary dispenser should the first gun fail. 
     These and other objects, features, and advantages can be accomplished by causing a dispenser to dispense a first pattern of material onto a substrate; causing another dispenser to dispense a second pattern of material onto the substrate; and upon the detection of the failure of material to be dispensed by one of the dispensers, automatically causing the other dispenser to dispense both first and second patterns of material onto the substrate. 
     These and other objects, features, and advantages can also be accomplished by a method for depositing a material pattern onto a substrate comprising the steps of: dispensing material from a first dispenser so as to deposit a first portion of the pattern of material on the substrate; then dispensing material from a second dispenser to deposit a second portion of the pattern of material on the substrate; sensing the material dispensed from said first and second sensors; and upon determining the absence of the first or second portion of the pattern of material dispensed, automatically causing one of said dispensers to deposit both the first and second portions of the pattern of material to be deposited onto a subsequent substrate. 
     These and other objects, features, and advantages can be further accomplished by a method for dispensing material comprising the steps of: determining a first actuation sequence; determining a second actuation sequence; determining a third actuation sequence; controlling the actuation of a first dispenser, for dispensing material, in accordance with the first actuation sequence; controlling the actuation of a second dispenser for dispensing material, in accordance with the second actuation sequence; detecting the failure of the first dispenser to dispense the material; and controlling the actuation of the second dispenser in accordance with the third actuation sequence. 
     These and other objects, features, and advantages can be further accomplished by a method for dispensing adhesive onto a substrate in a pattern having a plurality of discrete adhesive deposits comprising the steps of: a) alternating the actuation of two adhesive dispensers, to dispense discrete streams or drops of adhesive onto the substrate in a pattern; b) sensing the dispensed adhesive; and c) upon the detection of a failure to dispense adhesive, causing a de-activation of the dispenser failing to dispense the adhesive and causing the other dispenser to be actuated to dispense the discrete streams or drops of adhesive from the discharge orifice in order to maintain said pattern. 
     These and other objects, features, and advantages can be further accomplished by a method of dispensing adhesive onto a substrate comprising the steps of: a) dispensing the adhesive from a first dispenser onto a substrate to produce a first dispensed pattern while maintaining a second dispenser in a standby condition; b) cycling the dispensers from standby to dispense and from dispense to standby after one of the following: i) a period of time, ii) a number of gun firings, or iii) a number of substrates; and c) upon receiving a signal indicating the failure to detect the proper amount of adhesive dispensed, automatically de-activating the dispenser while causing the dispenser in standby to be actuated to dispense the adhesive onto the substrate to produce the first dispensed pattern on at least a subsequent substrate. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The following is a brief description of the drawings in which like parts may bear like reference numerals and in which: 
     FIG. 1 is a diagrammatic view according to one embodiment of the invention, illustrating a portion of an adhesive dispensing system; 
     FIG. 1A is a diagrammatic view according to an alternative mounting arrangement of one set of guns according to the invention, illustrating a portion of an adhesive dispensing system; 
     FIG. 2 is a partial enlarged elevational view of the dispensing system of FIG. 1; 
     FIGS. 3A-3D are various adhesive dispensing patterns; 
     FIG. 4 is another embodiment of a dispensing system according to the invention; and 
     FIG. 5 is another embodiment of a dispensing system according to the invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     With reference to FIGS. 1 and 2, a portion of an adhesive dispensing system is shown generally as reference No.  10 . The adhesive dispensing system  10  includes at least a pair of dispensers  12  and  14 . Other pairs of dispensers may also be included, such as for example  16  and  18 . Each dispenser, may include a valve operated module  20 , commonly referred to as a gun module. The gun module  20  may also include a nozzle  22  attached to the outlet of the gun module. The gun module may, for example, be a pneumatically operated valve, such as for example, a Nordson® Model H-200, Model H-400, or Model CF®-200 gun modules manufactured and sold by Nordson Corporation, Westlake, Ohio. The gun module  20  may alternatively be electrically driven and may be, for example, a Nordson Model E-700, E-350, or other electric gun modules manufactured and sold by Nordson Corporation. The gun modules may dispense the material as an extruded bead, drops, droplets, a spray, a swirl spray, etc. 
     The dispensers  14  and  16 , may for example, be positioned above a moving conveyor  24  which transports a substrate  26 . For example, the substrate may be a carton, a box, a web, a circuit board or some other object which requires a material to be dispensed onto it. While the material to be deposited is described herein as an adhesive, other materials may be dispensed, such as for example, gasketing materials, sealants, caulks, coatings, fluxes, encapsulants, and paints. While it is preferred that the material to be dispensed is a hot melt adhesive it need not be as other types of non-hot-melt-adhesive may be used instead, including a water base adhesive, commonly known as “cold glue”, as well as epoxies. 
     The gun modules of each dispenser may be attached to a manifold or service block  28 . Typically the manifold  28  includes internal passageways for supplying the adhesive to each dispenser. The manifold in turn is typically coupled to a source of adhesive (not shown), such as for example, an applicator unit, drum unloader, etc. for supplying the material to the manifold. The manifold  28  may also be coupled to a source of pressurized air (not shown) to provide air to the dispensers in pneumatically driven modules. In hot melt applications, the manifold will also include internal heaters, transferring heat to the hot melt adhesive, so as to maintain the liquified hot melt adhesive at its proper application temperature. 
     The actuation of the dispensers  12  and  14  are commonly controlled by a controller  30 , via output signals shown generally as lines  32  and  34 . In a pneumatic dispenser, the controller  30  provides the electrical power necessary to drive the air solenoid in such a manner as to control the opening and closing of the dispenser in accordance with a desired dispensing pattern. 
     In other words, the outputs  32 ,  34  of the controller control the actuation of the air solenoids (not shown) which in turn provide air to drive the opening and/or the closing of the piston of the pneumatic valve. The outputs generated by the controller therefore controls the dispensers in such a manner that the appropriate pattern of material is deposited onto the substrate. The desired pattern is programmed into a controller, sometimes referred to as a pattern controller, in order to obtain the desired pattern necessary for a particular application. 
     In electrical guns, a solenoid, integral to the gun, drives an armature. Typically, the armature is the plunger or needle which mates at one end with the valve seat to thereby control the flow of the adhesive from the nozzle. Electric guns are typically driven by higher voltage and power requirements than those necessary to drive the typical air solenoid. Therefore, the controller for an electric gun will include not only the pattern controls, but also the circuitry to provide the necessary power to drive the armature properly. Typically, the controller for an electric gun is referred to as a gun driver. 
     Typically a detector, for example a photo-detector (not shown) is positioned up stream of the dispensers  12 ,  14  to detect the approaching substrate  26 . The detector provides a signal to the controller  30  which is used in conjunction with the stored pattern. The determination of and storage of the appropriate pattern  36  necessary to produce the desired dispensed pattern of adhesive on a substrate is well known. Typically the stored pattern for a gun takes into account the speed of the substrate, the inherent on and off delays, etc. See for example, U.S. Pat. Nos. 4,166,246; 4,380,967; and 4,500,937 hereby incorporated by reference herein. 
     Therefore, the first dispenser or gun  12  is driven via the output  34  according to a pattern  36  stored in the controller  30 . Based on this pattern, the controller generates signals which in turn causes the gun to open and close to produce the desired pattern on the substrate. 
     The second dispenser or gun  14  of this pair, may be maintained in a standby condition. However when actuated, dispenser  14  will be driven by the controller in a manner in accordance with a second pattern  60  stored in the controller. 
     A sensor  40  is mounted in such a manner as to sense the material dispensed from dispenser  12 . The sensor  40 , may be positioned for example, between the nozzle  22  and the substrate  26 , thereby monitoring the material as it is being dispensed. Alternatively, a sensor  40   a  (indicated in phantom) may be mounted in such a manner as to monitor the dispensed material on the substrate. The sensor  40  generates a sensor signal  44  which corresponds to the presence or absence of the dispensed material, and is inputted to controller  30 . The sensor signal  44  received by the controller is compared to a reference to determine if material is being dispensed properly. When it is determined that the first dispenser has either failed to dispense adhesive or that the pattern is not complete, the controller will cause the output  32  to de-activate the first dispenser  12  while causing the second dispenser  14 , to be removed from its standby condition and to be actuated according to the second pattern  60  stored in the controller  30 . The sensor  40 , may be, for example, an infrared detector, an ultrasonic detector, an optical sensor, etc. depending upon the type of adhesive being dispensed. 
     Upon the detection of a failure of the material to be dispensed by the first dispenser  12 , the second dispenser  14  may begin its dispensing either with the next substrate  26  or, depending upon the placement of the sensing equipment, the speed of response, etc., the second dispenser  14  may begin to dispense material immediately onto the substrate, thereby placing at least some of the material onto the present substrate. While this latter method may result in the substrate not receiving a complete pattern or the proper amount of material, this may have, in certain circumstances, the benefit of allowing the substrate to be processed easier to a repair station while maintaining production. For example, in the sealing of beverage cartons, if the flap of the carton does not seal, the cans may fall from the container onto the conveyor and/or the production floor. This may cause a stoppage of the line until the cans and the container are removed. However, by causing the second dispenser  14  to immediately dispense adhesive onto the substrate, the amount of adhesive dispensed (while not necessarily enough to keep the container closed during normal shipment and handling), may be sufficient to keep the container closed long enough to be removed from the main conveyor line and sent to a repair station for proper gluing. This eliminates the potential opening of a container on the conveyor line thereby preventing unnecessary down time to the main processing line. 
     The materials that may be dispensed, including hot melt adhesives, may make it necessary in normal operation to cycle the second gun  14  to dispense material to prevent problems associated with a stagnate material. In such case, the guns may occasionally be alternated so that the first gun  12  may be placed in standby and the second gun  14  may now be the gun used for dispensing the adhesive onto the substrate. The rotation or cycling of the guns from a dispensing mode to a standby mode by be preprogrammed based on the passage of time, the number of substrates dispensed, gun firings, etc. 
     Generally, the outlet of nozzles  22 ,  22   a  of the first and second dispensers  12 ,  14  will be in line substantially with one another, in the direction of movement of the substrate, so that each is able to dispense the same pattern of material. The guns may be mounted in any number of ways to accomplish this. For example, with reference to FIG. 1A, the guns  12 ,  14  may be mounted to a manifold  28  wherein the manifold is in line with the direction of the movement of the substrate. However, there may be circumstances in which the exact placement of the adhesive may not be that critical and as a result the first and second dispensers may be somewhat offset. 
     Furthermore, the first and second dispensers may be configured to operate to dispense a portion of the pattern desire for each substrate. For example, with reference to FIGS. 3A-3D, if the pattern to be dispensed is a bead  46 , the first dispenser may dispense the first half of the bead  48  and the second half of the bead  50  may be dispensed by the second dispenser. Alternatively, the guns may be cycled ON/OFF through the course of a dispensing cycle to dispense various portions of the pattern. For example, the first dispenser may dispense various segments of the bead  52 , while the second dispenser dispenses other segments, thereby producing a completed bead. Similarly, the pattern could include a number of spaced apart segments or beads, commonly known as a stitching pattern wherein a number of beads or segments  56  are dispensed by one dispenser and the other beads  58  are dispensed by the second dispenser, see for example FIGS. 3C and 3D. 
     In cycling between the first  12  and second  14  guns to produce the pattern of adhesive to a substrate, a sensor  40   a  may monitor the dispensed pattern on the substrate as before or a first  40  and second  40   b  sensor may be used to dispense the material dispensed from the orifice of the first and second dispensers prior to its contacting the substrate. 
     Upon the sensing or the detecting of the failure of one of the first  12  or second  14  dispensers to dispense the material  42  properly, the other sensor is controlled to produce the pattern on the substrate that would have resulted from both guns. For example with reference to FIG. 3C, if the first dispenser is dispensing adhesive beads  56 , and the second dispenser is dispensing a second set of adhesive beads  58 , upon the detection that these patterns are not being dispensed properly, such as the absence of one or more of beads  56 , such as when the first gun has failed, will be de-activated and the second gun will now be controlled to produce the complete pattern of dispensed beads  56  and  58 . In other words, if the pair of guns  12 ,  14  were dispensing one of the patterns of FIGS. 3A-3D for example, and one failed, the other gun would be controlled to produce the desired pattern. 
     This may be accomplished, for example, by storing the a pattern  36  in the pattern controller to control the first dispensing gun  12 , and a second pattern  60  in the pattern controller to control the second dispensing gun  14 . A third pattern  62 , could be stored in the pattern controller such as to drive the first dispensers so that it will be able to produce the complete pattern that would normally be attained with both guns. A fourth pattern  63  could be stored in the pattern controller such as to drive the second dispenser so that it will be able to produce the complete pattern. Upon the detection that one of the dispensers has failed to properly dispense the material, the failed dispenser will be de-activated and the properly actuating dispenser will be then driven according to the complete pattern stored, either the third  62  or the fourth  63  pattern. 
     With reference to FIG. 4, it has been known to utilize two dispensing guns  64 ,  66  to feed one dispensing orifice/nozzle  68 . For example, U.S. Pat. No. 5,589,226, incorporated herein by reference, utilizes a pair of dispensing guns in order to provide faster cycling rates to produce smaller beads and/or smaller spacing between the beads or dots. In such an arrangement, the first and second dispensing guns are each controlled by a controller  30   a  with respect to a first  36   a  and second pattern  60   a  respectively. Upon the detection  70  that one of the dispensing guns  64 ,  66  has failed to properly dispense material, such as the absence of a bead, the other dispensing gun will be controlled by another stored pattern, such as third pattern  62   b  or fourth  63   a  as above, so as to be able to continue dispensing material. However, this will necessitate a reduction in the line speed. A signal  69  is sent to the controller  72  controlling the line speed so that the line speed controller  72  will produce an appropriate control signal  74  to the motor drive  76  of the conveyor  24   a  in order to reduce the line speed. Reducing the line speed may be necessary in order to allow the gun to have sufficient time to open and close in order to properly dispense material onto the substrate in the desired pattern. This allows the production to continue, albeit, at a reduced speed, until the failure can be corrected. 
     While the nozzles associated heretofore have been illustrated as a single orifice nozzle, they need not be. The nozzles, could in fact be slot nozzles, or multi-orifice nozzles for producing various patterns onto the substrate. However, the nozzles of the first and second dispensers will be generally need to be substantially the same, so as to be able to each provide the required pattern should one fail. 
     This invention may also be used for many other applications, including beer production. With reference to FIG. 5, for example, in the bottling of beer, once the bottle  80  has been filled with beer  82 , a dispenser  84  dispenses a shot of water  86  into the bottle of beer. This causes the beer to foam thereby producing gas which in turn evacuates the bottle of air prior to capping. A sensor  88  may be disposed between the orifice or nozzle  90  of the dispenser  84  and the mouth  92  of the bottle, if the sensor  88  fails to verify the shot of water dispensed from the first dispenser  84 , a second dispenser  94  could be activated to dispense the shot of water as the bottle  80  passed beneath it in order to ensure that the water was actually dispensed into the beer, thereby ensuring that air has been evacuated from the bottle prior to capping. 
     While certain representative embodiment details have been shown for the purposes of illustrating the invention, it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the scope of the invention. For example, upon the detection of a failure of one of the guns, an alarm may be indicated.