EP0359943A2 - Vorrichtung zum Sprühen von Schmelzklebern - Google Patents

Vorrichtung zum Sprühen von Schmelzklebern Download PDF

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Publication number
EP0359943A2
EP0359943A2 EP89113745A EP89113745A EP0359943A2 EP 0359943 A2 EP0359943 A2 EP 0359943A2 EP 89113745 A EP89113745 A EP 89113745A EP 89113745 A EP89113745 A EP 89113745A EP 0359943 A2 EP0359943 A2 EP 0359943A2
Authority
EP
European Patent Office
Prior art keywords
air
adhesive
plunger
flow
stream
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP89113745A
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English (en)
French (fr)
Inventor
Robert J. Woodlief
Charles H. Scholl
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Nordson Corp
Original Assignee
Nordson Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Nordson Corp filed Critical Nordson Corp
Publication of EP0359943A2 publication Critical patent/EP0359943A2/de
Withdrawn legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
    • B05B1/00—Nozzles, spray heads or other outlets, with or without auxiliary devices such as valves, heating means
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
    • B05B7/00—Spraying apparatus for discharge of liquids or other fluent materials from two or more sources, e.g. of liquid and air, of powder and gas
    • B05B7/02—Spray pistols; Apparatus for discharge
    • B05B7/08—Spray pistols; Apparatus for discharge with separate outlet orifices, e.g. to form parallel jets, i.e. the axis of the jets being parallel, to form intersecting jets, i.e. the axis of the jets converging but not necessarily intersecting at a point
    • B05B7/0807—Spray pistols; Apparatus for discharge with separate outlet orifices, e.g. to form parallel jets, i.e. the axis of the jets being parallel, to form intersecting jets, i.e. the axis of the jets converging but not necessarily intersecting at a point to form intersecting jets
    • B05B7/0815—Spray pistols; Apparatus for discharge with separate outlet orifices, e.g. to form parallel jets, i.e. the axis of the jets being parallel, to form intersecting jets, i.e. the axis of the jets converging but not necessarily intersecting at a point to form intersecting jets with at least one gas jet intersecting a jet constituted by a liquid or a mixture containing a liquid for controlling the shape of the latter
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
    • B05B7/00—Spraying apparatus for discharge of liquids or other fluent materials from two or more sources, e.g. of liquid and air, of powder and gas
    • B05B7/02—Spray pistols; Apparatus for discharge
    • B05B7/12—Spray pistols; Apparatus for discharge designed to control volume of flow, e.g. with adjustable passages

Definitions

  • This invention relates to apparatus for spraying hot melt adhesive, and, more particularly, to an apparatus for spraying droplets of molten thermo­plastic adhesive onto a substrate for subsequent bonding with another substrate.
  • Hot melt thermoplastic adhesives have been widely used in industry for adhering many types of products, and are particularly useful in applications where quick setting time is advantageous.
  • One appli­cation for hot melt adhesive which has met with considerable commercial success is the fabrication of cartons wherein the quick setting time of the hot melt adhesive is useful in assembling the flaps of a carton in high speed cartoning lines.
  • a number of dispensers have been employed to deposit hot melt adhesive onto the flaps of cartons, or on other substrates where quick setting time is required.
  • one type of adhesive dispenser is a gun formed with an adhesive passageway connected to a nozzle having a discharge orifice. The adhesive is pumped through the gun and ejected from the dis­charge orifice of the nozzle in the form of a rela­tively thick bead of molten thermoplastic adhesive which is applied to the substrate. Another substrate is then placed into contact with the first substrate to "flatten" or spread out the adhesive bead over a larger surface area so that an acceptable bond is produced between the substrates.
  • One disadvantage of adhesive dispensers which discharge an adhesive bead is that a relatively large quantity of adhesive is required to obtain the desired bond.
  • Molten thermoplastic adhesive is highly viscous and does not readily spread over the surface of one substrate even when a second substrate to be bonded thereto is pressed against the adhesive bead.
  • a relatively large quantity of adhesive is required in forming the bead to ensure the surface area of the bond between the substrates is sufficient to adhere the substrates together.
  • the hot melt adhesive is transmitted under pressure to the discharge orifice of a nozzle.
  • the hot melt adhesive is ejected into the ambient air, it atomizes and forms a spray or mist of tiny droplets which are deposited onto the sub­strate.
  • These small droplets cover a larger surface area than a single adhesive bead, and since bond strength is dependent in part on the surface area covered by the adhesive, a lesser quantity of adhesive in droplet form can be employed than is required with an adhesive bead.
  • thermoplas­tic material in tiny droplets onto a substrate
  • the nozzle in order for the adhesive to completely atomize before it reaches the substrate, the nozzle must be posi­tioned a relatively large distance from the substrate. As a result, the small droplets are exposed to ambient temperatures and tend to cool before they reach the substrate. It has been found that with some types of hot melt adhesives the droplets either harden before they contact the substrate or fail to retain suffi­cient specific heat after they reach the substrate to permit bonding to another substrate.
  • nozzles of the type designed to spray thermoplastic adhesive in atomized form can produce elongated strings or fibers of adhesive instead of droplets when the nozzle is first turned on and/or when the nozzle is shut off. These strings of adhesive tend to clog the nozzle and/or are deposited in that form onto the substrate.
  • a stream of hot melt adhesive ejected from the discharge orifice of a nozzle is impinged by a stream of atomizing air which contacts the outside of the adhesive stream to form droplets of adhesive whose size is controlled by varying the velocity and flow rate of the atomizing air so that such droplets retain sufficient heat when they are deposited on a substrate to subsequently bond to another substrate placed in contact therewith.
  • a stream of pattern-­shaping air which is controlled separately from the stream of atomizing air, is directed against the adhesive droplets before they reach the substrate to variably control the size and shape of the pattern of adhesive droplets on the substrate.
  • One aspect of this invention is predicated upon the elimination of cut-off drool in the operation of the apparatus, i.e., the elimination of elongated fibers or strands of adhesive formed at the discharge orifice of the nozzle when the flow of adhesive is shut off.
  • This is achieved in the instant invention by valves which control the discharge of adhesive from the nozzle of the spraying apparatus and the supply of atomizing air and pattern-shaping air to the discharge orifice of the nozzle.
  • the apparatus is formed with an applicator head having an adhesive passageway within which a plunger is axially movable between an open position which permits passage of adhesive to the nozzle and out its discharge orifice, and a closed position in which the flow of adhesive is blocked.
  • a plunger control valve is mounted within a pilot air line connected to the applicator head which controls the movement of the plunger between the open and closed position.
  • Atomizing air is supplied to the nozzle through an atomizing air passageway which has an atomizing air regulating valve connected therein.
  • Pattern-shaping air is supplied to the nozzle area through a pattern-shaping air passageway having a pat­tern-shaping air regulating valve connected therein which is adjustable separately from the atomizing air regulating valve.
  • Both the atomizing air regulating valve and pattern-shaping air regulating valve commu­nicate with a common supply line carrying heated or unheated air.
  • This common supply line has a pilot-­operated air supply valve located upstream relative to the regulating valves. Opening and closing of the pilot-operated air supply valve is controlled by an air control valve which communicates with a source of pressurized, pilot air.
  • Movement of the plunger in the adhesive supply passageway, and the flow of air through both the atomizing air passageway and pattern-shaping air passageway are synchronized so that atomizing and pattern-shaping air is supplied to the area of the discharge orifice of the nozzle both before the stream of adhesive is ejected from the discharge orifice and after the flow of adhesive is terminated.
  • the air control valve which operates the air supply valve is an "unrestricted in-metered out" type of valve , i.e., it allows an unrestricted flow of pilot air to flow in one direction therethrough so that the air supply valve is pressurized and quickly opens to permit the flow of a stream of atomizing air and a stream of pat­tern-shaping air toward the discharge orifice of the nozzle.
  • the air control valve meters the flow of air in the opposite direction so that the air supply valve is slowly depressurized and thus and slowly closes to stop the flow of atom­izing and pattern-shaping air after the flow of adhesive through the adhesive passageway has stopped. This eliminates "cut-off drool" or the formation of strings of adhesive at the discharge orifice of the nozzle.
  • the plunger control valve which supplies pilot air to axially move the plunger between the open and closed position operates in the opposite manner from the air control valve, i.e., such valve is a "metered in-unrestricted out" type of valve.
  • the plunger control valve meters the supply of pilot air therethrough to the plunger to delay movement of the plunger from a closed to an open position so that the flow of adhesive through the discharge orifice of the nozzle begins after the atomizing and pattern air flow has been initiated.
  • the plunger control valve is "unre­stricted out", i.e., the pilot air flowing to the plunger is allowed to bleed in the opposite direction through the plunger control valve along an unrestrict­ed path so that a spring can quickly return the plunger to a closed position before the flow of air from the atomizing and pattern-shaping air passageways is discontinued.
  • Another aspect of this invention is pred­icated upon controlling both the size of the droplets formed from the adhesive stream, and the pattern of droplets deposited on a substrate.
  • This is achieved by the air flow regulating valves in both the atomiz­ing air passageway and the pattern-shaping air pas­sageway which are controlled separately from one another to vary the air flow therein. Heated or unheated air is supplied through the air supply valve to each of the regulating valves, and such regulating valves are individually adjustable to direct a select­ed portion of the air flow into the atomizing air passageway and the pattern air passageway.
  • the air discharged from the atomizing air passageway impacts the outside of the stream of adhesive discharged from the nozzle so that the adhesive stream is broken up into blobs or droplets having a diameter of preferably about 1/4-7/16 inches.
  • the width of the pattern of these droplets on a substrate is primarily controlled by the pattern-­shaping air which contacts the droplets after they are formed but well before they reach the substrate.
  • the ratio of the flow rate and velocity of the atomizing air to the pattern-shaping air is adjustable by operation of the air regulating valves. Generally, as the ratio of the velocity and flow rate of the atomizing air to the pattern-shaping air is adjusted so that the velocity and flow rate of the atomizing air increases while that of the pattern-­shaping air decreases, a relatively narrow spray pattern is produced on a substrate which contains relatively small adhesive droplets. On the other hand, if the ratio of the velocity and flow rate of the atomizing air to the pattern-shaping air is adjusted so that the velocity and flow rate of the atomizing air decreases while that of the pattern-­shaping air increases, a relatively wide spray pattern is produced on a substrate which contains relatively large adhesive droplets.
  • the applicator head is adapted to mount to the gun body of a hand held spray gun having an air control valve and a plunger control valve each connected to a source of pressurized air through a trigger operated supply valve.
  • the applica­tor head is mounted to the gun body and connected to the air control valve and plunger control valve for operation as described above.
  • a rod supported mounting block is provided for connection to the applicator head.
  • the mounting block supports the air control valve, the plunger control valve and carries a supply line for adhesive, all of which are connected to the applicator head as in the hand held spray gun applica­tion. Pilot air to the air control valve and plunger control valve is supplied through lines connected to a controller, e.g., a programmable control device, which is capable of automatically controlling the flow of pilot air to the mounting block, and, in turn, the applicator head.
  • a manifold is provided which is adapted to support a number of individual applicator heads and control the flow of pilot air and adhesive to each.
  • the supply of pilot air and adhesive to the manifold is con­trolled by a programmable controller so that adhesive is discharged from each of the applicator heads at the desired intervals of time and with the desired pat­tern.
  • the adhesive spray apparatus 10 is adapted for hand held operation and comprises a spray gun 12 having a handle 14 connected to a gun body 16.
  • a trigger 18 carried on a pivot 20 mounted to the gun handle 14 is connected by an actuator 22 to a trigger rod 24 movable axially within the gun body 16.
  • the end of the trigger rod 24 opposite the trigger 18 is mounted to a connector plate 26 which, in turn, contacts a valve plunger 28.
  • a three-way cartridge valve 30 is carried by the gun body 16 and is operatively connected to the valve plunger 28.
  • One side of the cartridge valve 30 is connected to a source of actuating air (not shown) through a feed line 32.
  • Branch lines 34, 36 extend outwardly from the cartridge valve 30 at outlet ports 38 and 40, respectively, formed therein.
  • the cartridge valve 30 is a commercially available item and forms no part of this invention per se.
  • the trigger 18 In order to open the cartridge valve 30 to permit the flow of air from feed line 32 into each of the branch lines 34, 36, the trigger 18 is first pulled to the left as viewed in Fig. 1 carrying the trigger rod 24 and connector plate 26 in the same direction. Movement of the connector plate 26 rela­tive to the valve plunger 28 opens an internal seat (not shown) of the cartridge valve 30 allowing the passage of air from the feed line 32 through cartridge valve 30 and into each of the branch lines 34, 36. The cartridge valve 30 is placed in the closed posi­tion by releasing trigger 18 so that a spring (not shown) returns the trigger rod 24 and connector plate 26 to their original positions with respect to the valve plunger 28. See Fig. 1.
  • the flow of air through the cartridge valve 30 into branch lines 34, 36 provides pilot air which controls the flow of adhesive, and the flow of atomiz­ing and pattern-shaping air, as discussed in detail below.
  • the structure for obtaining the air flow, and for obtaining the adhesive flow, is described sepa­rately below.
  • the gun body 16 is connected to a service body 41 which mounts an applicator head 44.
  • the service body 41 carries adhesive heaters and other electrical compo­nents which form no part of this invention per se and are not described herein.
  • a support block 42 is connected to the applicator head 44 having an air supply valve 46 located at its base which receives heated or unheated air from a supply line 48.
  • the air supply valve 46 comprises a plunger 50 which extends between a pilot air chamber 52 and an air inlet chamber 54 both formed in the support block 42.
  • the pilot air chamber 52 is formed with a port 55 connect­ed to a pilot air supply line 57, which, in turn, is connected to the branch line 36 from cartridge valve 30.
  • a seal 56 is interposed between the chambers 52, 54 and is formed with a bore within which the plunger 50 is axially slidable.
  • the end of plunger 50 located within the pilot air chamber 52 carries a head plate 58, and the opposite end of plunger 50 located within the air inlet chamber 54 mounts a plunger head 60.
  • the plunger head 60 is adapted to engage a seat 62 formed in the air inlet chamber 54 at the entrance to a passageway 64 in the support block 42.
  • the passageway 64 is connected at the abutting faces of support block 42 and applicator head 44 to an air supply passageway 66 formed in the applicator head 44.
  • An O-ring 67 is positioned between the abutting faces of support block 42 and applicator head 44 to form a seal therebetween.
  • pilot air is supplied from the cartridge valve 30 into each of the branch lines 34 and 36.
  • a pilot air control valve 68 is connected between the branch line 36 and the pilot air supply line 57.
  • the pilot air control valve 68 a commercially available "unrestrict­ed in-metered out" type of actuating valve, i.e., the flow of pressurized, pilot air is allowed to flow in an unrestricted path in one direction through valve 68, but the air flow in the opposite direction through valve 68 is metered.
  • the pilot air control valve 68 When supplied with pressurized air from branch line 36, the pilot air control valve 68 allows an unrestricted flow of pilot air there­through which is transmitted through the pilot air supply line 57 to the pilot air chamber 52 of valve 46. Pressurization of the pilot air chamber 52 moves the head plate 58 of plunger 50 to the left as viewed in Fig. 1, thereby unseating the plunger head 60 from the seat 62 in air inlet chamber 54. As a result, air supplied to the air inlet chamber 54 through supply line 48 is allowed to enter the passageway 64 in support block 42 and flow to the air supply passageway 66 in the applicator head 44.
  • pilot air control valve 68 is operable to meter the flow of air there­through which gradually bleeds back in the opposite direction from the pilot air chamber 52 of valve 46 and through the pilot air supply line 57.
  • a spring 72 mounted within the air inlet chamber 54 of air supply valve 46 forces the plunger head 60 of plunger 50 into engagement with the seat 62 to close the flow of air from the air inlet chamber 54 into passageways 64, 66.
  • the applicator head 44 comprises an upper cylinder 74 connected to a base 76 within which the air supply passageway 66 is formed.
  • the base 76 is formed with a stepped bore 78 having an upper end which mounts a sleeve 80, and a smaller diameter, lower end forming an adhesive flow passageway 82.
  • the sleeve 80 is formed with an annular slot 84 extending radially inwardly from the outer surface thereof which communicates with the air supply passageway 66 formed in the base 76.
  • An atomizing air branch line 88 is connected to the annular slot 84, and a pattern-shaping air branch line 90 is also connected to the annular slot 84.
  • These branch lines 88, 90 receive air from the air passage­way 66 via the annular slot 84 for transmission to a nozzle 92 and air cap 94 mounted to the base 76 as described below.
  • the base 76 is formed with a threaded bore 96 which receives an atomizing air regulating valve 98 therein.
  • the regulating valve 98 has a chamber 100 connected to a discharge orifice 102.
  • a plunger 104 is carried by the regulating valve 98 which includes a rod 106 extending axially therethrough.
  • the outer end of the rod 106 is connected to a cap 108 exteriorly of the valve 98.
  • the inner end of rod 106 has a tapered edge 110 which is adapted to mate with a seat 112 formed in the regulating valve 98 at the intersection of chamber 100 and discharge orifice 102.
  • An annular slot 114 is formed in the outer surface of regulating valve 98 which is connected to the atomizing air branch line 88 carrying air from supply line 57. Radial passageways 116 connect the annular slot 114 to the chamber 100 of the regulating valve 98 upstream relative to the discharge orifice 102.
  • the flow of air from branch line 57 through the flow path defined by passageways 64, 66, branch line 88, slot 114, passageways 116 and chamber 100 is controlled as it passes through discharge orifice 102 by rotating the cap 108 and thus moving the rod 106 axially within the regulating valve 98.
  • Axial move­ment of the rod 106 varies the space between the tapered edge 110 of rod 106 and the seat 112 at the entrance to the discharge orifice 102 which, in turn, controls the flow rate of air passing therebetween.
  • Atomizing air is ejected from the discharge orifice 102 of regulating valve 98 into a connector passageway 118 formed in the base 76 of applicator head 44.
  • This connector passageway 118 terminates in an annular chamber 120 formed at the upper end of a threaded bore 122 in base 76 within which the nozzle 92 is mounted.
  • the nozzle 92 is formed with a plural­ity of radial passageways 124 having upper ends which communicate with the annular chamber 120.
  • the opposite, lower end of the radial passageways 124 terminate at the tip 126 of the nozzle 92 within an annular atomizing air discharge passageway 128 formed between the outer surface of the nozzle tip 126 and a facing surface 130 of the air cap 94.
  • atomizing air discharged from the atomizing air discharge passageway 128 impacts a stream of adhesive ejected from the nozzle 92 to break up such adhesive into droplets for deposition onto a substrate.
  • pattern-shaping air is transmitted to the nozzle 92 in a manner similar to the atomizing air described above.
  • the structure and operation of pattern-shaping air regulating valve 132 is identi­cal to that of atomizing air regulating valve 98 and is not repeated herein.
  • the same reference numerals are used on regulating valve 132 to designate the same structure as in regulating valve 98, with the addition of a "prime" to the reference numbers for the pat­tern-shaping air regulating valve 132.
  • the discharge orifice 102′ of pattern-­shaping air regulating valve 132 communicates with a connector passageway 134 formed in the base 76 of applicator head 44.
  • the connector passageway 134 terminates at an annular chamber 136 formed in the base 76 which, in turn, is connected to a plurality of radial passageways 138 formed in the nozzle 92.
  • the radial passageways 138 are connected to an annular chamber 140 formed around the periphery of nozzle 92.
  • the chamber 140 communicates with one end of a pair of pattern air-shaping passageways 144 formed in air cap 94.
  • the opposite end of the pattern air-shaping passageways 144 terminate at at least one orifice 146 formed in each air horn 148 of air cap 94.
  • pattern-shaping air is ejected from the discharge orifice 146 of each pattern air-shaping passageway 144 and impacts the droplets of hot melt adhesive formed by the atomizing air ejected from the atomizing air discharge passageway 128.
  • This pattern-shaping air controls the width of the pattern of adhesive deposited onto a substrate, i.e., the height and width of the pattern of droplets on the substrate.
  • both regu­lating valves 98, 132 are connected to the common air supply passageway 66 and thus the total flow of air in the system is divided among the atomizing air and pat­tern-shaping air branch lines 88, 90.
  • the upper cylinder 74 is formed with the stepped bore 156 having a lower end connected by an adhesive connector passageway 150 to a supply line 152 from a source of adhesive (not shown). See also Fig. 1.
  • This lower end of stepped bore 156 mounts the upper portion of sleeve 80 thus forming a flow path for molten hot melt adhesive from passageway 150 in upper cylinder 74 into the adhesive flow passageway 82 in base 76 of applicator head 44.
  • the upper end of stepped bore 156 mounts a packing cartridge 158 formed with a recess 162.
  • a compression spring 163 is received within the recess 162, and mounts to the upper end 164 of a plunger 165 which is carried by the packing cartridge 158 and is axially movable there­along.
  • a header plate 166 is mounted at the top of plunger 165 by a nut 168 forming an air chamber 171 between the packing cartridge 158 and header plate 166.
  • the outer edge of header plate 166 seals against an inner wall 169 of a cap 170 forming the top of applicator head 44. Pilot air is supplied by a feed line 153 connected to a passageway 154 formed in the upper cylinder 74 beneath the header plate 166 of plunger 165 and into air chamber 171. See also Figs. 1 and 2.
  • the lower end 172 of plunger 165 extends downwardly from the upper cylinder 74 through the adhesive flow passageway 82 in base 76 to the nozzle tip 126 of nozzle 92.
  • An adhesive discharge passage­way 178 (shown closed) is formed in the nozzle 92 having an upper end connected to the adhesive flow passageway 82 in base 76 and a discharge orifice 180 at the nozzle tip 126.
  • the nozzle tip 126 is tapered at the discharge orifice 180 to mate with the tapered tip 184 formed in the lower end 172 of plunger 165 to control the flow of adhesive therethrough.
  • the flow of adhesive through the spray apparatus 10 is obtained by axial movement of the plunger 165 relative to the discharge orifice 180 in the nozzle 92, and movement of the plunger 165 is controlled as follows. Air entering the branch line 34 through operation of valve 30, as described above, flows to a plunger control valve 186 connected to branch line 34. In turn, the plunger control valve 186 controls the flow of pilot air into the feed line 153 and through the passageway 154 formed in the upper cylinder 74 beneath the header plate 166 of plunger 165.
  • the plunger control valve 186 is a standard, commercially available "metered in-unrestricted out" type of actuating valve.
  • the flow of pilot air from branch line 34 is metered in one direction through the plunger control valve 186 into feed line 153 and through the passageway 154 and then beneath the plunger header plate 166.
  • the header plate 166 is forced upwardly from the top of the upper cylinder 74 toward the cap 170 thereabove.
  • the tapered tip 184 of plunger 165 is lifted upwardly from the tapered seat in nozzle tip 126 so that adhesive flowing through the adhesive discharge passageway 178 in nozzle 92 is ejected from the discharge orifice 180 of nozzle tip 126.
  • the plunger 165 places the compression spring 163 in compression against the lower guide 160.
  • the plunger control valve 186 is operable to permit the unre­stricted flow of air in the opposite direction there­through, i.e., the air contained beneath the header plate 166, in air chamber 171, within passageway 154 and within feed line 153 is allowed to bleed back through plunger control valve 186 without restriction and then vents to atmosphere through the three-way cartridge valve 30.
  • the compression spring 163 forces the plunger 172 downwardly as viewed in Fig. 3 so that its tapered tip 184 seats within the discharge orifice 180 of the nozzle tip 126.
  • the plunger control valve 186 and pilot air control valve 68 connected to branch lines 34 and 36, respectively, operate so that atomizing air and pattern-shaping air are supplied to the area of the nozzle tip 126 both before the adhesive flow through the nozzle 92 is initiated, and after the adhesive flow therethrough is terminated.
  • the pilot air control valve 68 is an "unrestricted in-metered out” type of valve whereas the plunger control valve 186 is a "metered in-unrestricted out” type of valve.
  • pilot air is quickly supplied by the pilot air control valve 68 to the air supply valve 46 which, in turn, allows atomizing air and pattern-shaping air to flow to the area of the nozzle tip 126 as described above.
  • the plunger control valve 186 is "metered in” so that pressurization of the air chamber 171 in upper cylin­der 74 is slightly delayed. The axial, upward move­ment of the plunger 165, and subsequent discharge of adhesive from nozzle 92, therefor occurs after atomiz­ing air and pattern-shaping air are present at the nozzle tip 126.
  • the "unrestricted out” plunger control valve 186 ensures that the flow of adhesive from nozzle 92 is terminated before the pilot air within the pilot air chamber 52 of air supply valve 46 is bled off by the "metered out” pilot air control valve 68, thus allowing air supply valve 46 to close and stop the air flow to the atomizing and pattern-shaping air lines.
  • valves 68, 186 in this manner substantially eliminates cut-off drool, i.e., the formation of strands or thin fibers of adhesive in the area of the nozzle tip 126. No excess adhesive is allowed to remain in the area of the discharge orifice 180 of the nozzle tip 126 after the flow of adhesive is discontinued because the atomizing air and pat­tern-shaping air continues for some period of time after the flow of adhesive is shut down. Similarly, no start-up drool or formation of strand-like fibers of adhesive is obtained when the flow of adhesive is initiated because the atomizing air and pattern-shap­ing air is directed to the nozzle tip 126 prior to the time the adhesive flow begins.
  • an adhesive stream 188 is ejected from the discharge orifice 180 of nozzle tip 126 and encounters the atomizing air ejected from the atomizing air discharge passageway 128.
  • the atomizing air expands radially outwardly from the discharge passageway 128 and impacts the exterior surface of the adhesive stream 188 with sufficient flow rate and velocity so that the adhesive stream 188 is broken up into globules or droplets 190 for deposi­tion onto a substrate 192.
  • These droplets 190 are then impacted by pattern-shaping air ejected from the discharge orifices 146 in the air horns 148 to control the width of the pattern of adhesive droplets 190 deposited onto the substrate 192.
  • An important aspect of this invention is the versatility of the operation of applicator head 44 in accommodating a number of different types of hot melt adhesives to obtain the desired size and pattern of adhesive droplets 190.
  • Thermoplastic adhesives have a relatively long "open time", i.e., the time in which they remain sufficiently molten to bond one substrate to another, but the open time of different types of thermoplastic adhesive varies from one to another.
  • some thermoplastic adhesives are pressure sensitive and thus have an extended open time wherein the adhesive can provide an effective bond even after it cools.
  • the applicator head 44 of this invention is operable to spray various types of hot melt adhesives in droplet form such that the individual droplets 190 are large enough to retain their specific heat once deposited onto a substrate 192 for a sufficient time period to permit a second substrate to be adhered to the first substrate 192.
  • This is achieved in the instant invention by the provision of separate control valves 98 and 132 for the atomizing air and pattern-­shaping air, respectively.
  • the flow rate of the atomizing air and its velocity are primarily responsible for the size of the adhesive droplet produced for a given nozzle design.
  • An increase in flow rate and velocity of the atomizing air tends to decrease the size of the adhesive droplets 190 because the adhesive stream 188 is impacted more violently by the higher velocity atomizing air which breaks it up into smaller droplets 190.
  • a decrease in the flow rate and velocity of the atomizing air tends to produce droplets 190 of larger size because of the reduced turbulence or violence of the impact between the slower moving atomizing air and adhesive stream 188.
  • the size of the droplets 190 can be adjusted for different types of hot melt adhesives to match or correspond to the open time thereof so that the droplets 190 are large enough to retain their specific heat once deposited onto the substrate 192 for a sufficient time to create an effective bond with another substrate.
  • hot melt adhesives with limited open time should be sprayed in relatively large droplets 190 and the size of the droplets 190 can be decreased as the open time of the adhesive increases or when using pressure sensitive adhesives.
  • the velocity and flow rate of the pattern-­shaping air is adjustable primarily by adjustment of pattern-shaping air regulating valve 132 to control the width of the pattern of droplets 190 deposited onto the substrate 192.
  • pattern-shaping air regulating valve 132 to control the width of the pattern of droplets 190 deposited onto the substrate 192.
  • the pattern of droplets 190 tends to widen.
  • the flow rate and velocity of the pattern-shaping air decreases, the resulting pattern of droplets 190 narrows on the substrate 192.
  • the ratio of the flow rate and velocity of atomizing air to pattern-shaping air would be adjusted instead of adjusting only one of the atomizing air stream or the pattern-shaping air stream while maintaining the other constant.
  • adjustment of the ratio of atomizing air to pattern-shaping air so that the velocity and flow rate of the atomizing air increases while the velocity and flow rate of the pattern-­shaping air decreases results in the formation of a relatively narrow spray pattern on substrate 192 consisting of relatively small droplets 190.
  • Adjust­ment of the ratio of atomizing air to pattern-shaping air so that the velocity and flow rate of the atomiz­ing air decreases while the velocity and flow rate of the pattern-shaping air increases results in the formation of a relatively wide spray pattern on substrate 192 consisting of relatively large droplets 190.
  • thermoplastic adhesives which are commercially available, and the differing requirements of the types of applications for which such adhesives are utilized, it is contem­plated that the ratio of the flow rate and velocity of atomizing air to pattern-shaping air for a particular application would be determined by experimenting with the settings of the atomizing air regulating valve 98 and pattern-shaping air regulating valve 132.
  • the particular configuration of the nozzle 92 employed in the applicator head 44 affects the velocity of the atomizing air and the pattern-shaping air depending upon the dimensions of the annular atomizing air passageway 124 and the two pattern-­shaping air orifices 146 in the air horns 148 of the air cap 94.
  • Adhesive Eastman A148 adhesive Adhesive Temperature: 375°F Adhesive Flow Rate: 300 g/min Nozzle Spacing: 12" from substrate Atomizing Air Flow Rate: 2.76 scfm Pattern-Shaping Air Flow Rate: 3.22 scfm
  • the stream of adhesive discharged from the spray nozzle was impacted in this Example 1 by a stream of atomizing air having a flow rate of 2.76 scfm.
  • the pattern of droplets 190 obtained by the stream of pattern-shaping air at a flow rate of 3.22 scfm was approximately 14" in width.
  • the size of the droplets 190 was considered sufficient to insure that they would have sufficient open time for the desired application.
  • Adhesive Eastman A148 adhesive Adhesive Temperature: 375°F Adhesive Flow Rate: 300 g/min Nozzle Spacing: 12" from substrate Atomizing Air Flow Rate: 3.47 scfm Pattern-Shaping Air Flow Rate: 3.21 scfm
  • Example 2 the same adhesive and adhesive flow rate was employed as in Example 1. The difference in this example is that the flow rate of the atomizing air was increased relative to the flow rate of the pattern-shaping air. This produced adhesive droplets 190 which were slightly smaller in transverse dimension, and also the pattern width decreased so that the droplets 190 were more tightly grouped together, than in Example 1.
  • a schematic illus­tration is provided of the adaptability of applicator head 44 to different dispensing systems.
  • the applica­tor head 44 is useful for hand-held types of opera­tions as shown in Figs. 1-3 and at the top of Fig. 4, and for more automated applications as shown in intermediate and lower segments of Fig. 4 wherein the applicator head 44 mounts to different support means which supply pilot air, adhesive and heated air to the applicator head 44.
  • Fig. 4 illustrates the applicator head 44 in combina­tion with the spray gun 12 shown in Fig. 1 and discussed in detail above. This combination would be utilized in hand held applications for applicator head 44 such as certain types of assembly operations.
  • the spray gun 12 is eliminated and replaced by a mounting block 200 supported by a rod 202.
  • the mounting block 200 carries the service block 41 which, in turn, mounts the applicator head 44 in a position to support the support block 42.
  • the service block 41 is formed with a port 204 to receive pilot air for the plunger 165 of applicator head 44 and a port 209 for hot melt adhesive.
  • a port 206 is formed in support block 42 to receive air for the atomizing and pat­tern-shaping passageways of applicator head 44, and a port 208 is also formed in support block 42 to receive pilot air for operating an air supply valve (not shown) such as the air supply valve 46.
  • an air supply valve not shown
  • a manifold 210 is illustrated which is supported on a mounting rod 212.
  • the manifold 210 is adapted to mount several applicator heads 44 on either of its sides, each of which are operated by a programmable controller (not shown).
  • ports are provided to mount two applicator heads on one side and one applicator head on the opposite side.
  • the manifold 210 is formed with ports 214 adapted to connect to the port 154 of applicator head 44 to supply pilot air for moving the plunger within applicator head 44. Hot melt adhesive is transmitted into the passage 150 of applicator head 44 from ports 216.
  • the manifold 210 is formed with ports 218 which connect to the port 66 in applicator head 44 to supply air for the atomizing air and pattern-shaping air passageways thereof.
  • the manifold 210 has suitable passageways (not shown) which connect control air supply line 215 with ports 214, hot melt adhesive supply line 219 with ports 216 and shaping and atomizing air supply line 219 with ports 218.

Landscapes

  • Nozzles (AREA)
  • Application Of Or Painting With Fluid Materials (AREA)
  • Coating Apparatus (AREA)
EP89113745A 1988-09-21 1989-07-25 Vorrichtung zum Sprühen von Schmelzklebern Withdrawn EP0359943A2 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US24736688A 1988-09-21 1988-09-21
US247366 1988-09-21

Publications (1)

Publication Number Publication Date
EP0359943A2 true EP0359943A2 (de) 1990-03-28

Family

ID=22934649

Family Applications (1)

Application Number Title Priority Date Filing Date
EP89113745A Withdrawn EP0359943A2 (de) 1988-09-21 1989-07-25 Vorrichtung zum Sprühen von Schmelzklebern

Country Status (7)

Country Link
EP (1) EP0359943A2 (de)
JP (1) JPH02135165A (de)
KR (1) KR900004410A (de)
AU (1) AU4109489A (de)
BR (1) BR8904392A (de)
CA (1) CA1336373C (de)
NO (1) NO893140L (de)

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0584973A2 (de) * 1992-08-27 1994-03-02 Nordson Corporation Spritzpistole für Substratbeschichtung
US5409733A (en) * 1992-07-08 1995-04-25 Nordson Corporation Apparatus and methods for applying conformal coatings to electronic circuit boards
US5423935A (en) * 1992-07-08 1995-06-13 Nordson Corporation Methods for applying discrete coatings
EP0682986A2 (de) * 1994-05-11 1995-11-22 F.LLI TALAMONTI MACCHINE S.n.c. Sprühpistole zum Klebstoffauftrag
EP0850694A1 (de) * 1996-12-27 1998-07-01 ITW Oberflächentechnik GmbH Ventil für eine Sprühbeschichtungseinrichtung mit mindestens zwei Fluidwegen
EP0978322A3 (de) * 1998-08-05 2003-09-10 Nordson Corporation Ausgabevorrichtung mit einer Düse zur Abflussregelung einer erwärmten Flüssigkeit durch Verwendung von nicht erwärmter Druckluft
WO2011069135A1 (en) * 2009-12-04 2011-06-09 Mt Industries, Inc. Hand held skin treatment spray system with proportional air and liquid control
WO2011041148A3 (en) * 2009-10-01 2011-07-21 3M Innovative Properties Company Self-contained, sprayable, silyl terminated adhesive systems
US8784390B2 (en) 2009-12-04 2014-07-22 Sunless, Inc. Skin treatment spray nozzle system for automatic spray gantry
US9278367B2 (en) 2012-09-17 2016-03-08 Sunless, Inc. Precision pumping system for spray treatment cycles
US20160108511A1 (en) * 2013-05-06 2016-04-21 Hp Pelzer Holding Gmbh Spray-coating method

Cited By (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5409733A (en) * 1992-07-08 1995-04-25 Nordson Corporation Apparatus and methods for applying conformal coatings to electronic circuit boards
US5423935A (en) * 1992-07-08 1995-06-13 Nordson Corporation Methods for applying discrete coatings
US5683036A (en) * 1992-07-08 1997-11-04 Nordson Corporation Apparatus for applying discrete coatings
EP0584973A2 (de) * 1992-08-27 1994-03-02 Nordson Corporation Spritzpistole für Substratbeschichtung
EP0584973A3 (de) * 1992-08-27 1995-06-14 Nordson Corp Spritzpistole für Substratbeschichtung.
EP0682986A2 (de) * 1994-05-11 1995-11-22 F.LLI TALAMONTI MACCHINE S.n.c. Sprühpistole zum Klebstoffauftrag
EP0682986A3 (de) * 1994-05-11 1997-12-17 F.LLI TALAMONTI MACCHINE S.n.c. Sprühpistole zum Klebstoffauftrag
EP0850694A1 (de) * 1996-12-27 1998-07-01 ITW Oberflächentechnik GmbH Ventil für eine Sprühbeschichtungseinrichtung mit mindestens zwei Fluidwegen
EP0978322A3 (de) * 1998-08-05 2003-09-10 Nordson Corporation Ausgabevorrichtung mit einer Düse zur Abflussregelung einer erwärmten Flüssigkeit durch Verwendung von nicht erwärmter Druckluft
WO2011041148A3 (en) * 2009-10-01 2011-07-21 3M Innovative Properties Company Self-contained, sprayable, silyl terminated adhesive systems
CN102686319A (zh) * 2009-10-01 2012-09-19 3M创新有限公司 独立喷涂型甲硅烷基封端的粘合剂系统
CN102686319B (zh) * 2009-10-01 2016-02-24 3M创新有限公司 独立喷涂型甲硅烷基封端的粘合剂系统
WO2011069135A1 (en) * 2009-12-04 2011-06-09 Mt Industries, Inc. Hand held skin treatment spray system with proportional air and liquid control
US8486030B2 (en) 2009-12-04 2013-07-16 Sunless, Inc. Hand held skin treatment spray system with proportional air and liquid control
US8784390B2 (en) 2009-12-04 2014-07-22 Sunless, Inc. Skin treatment spray nozzle system for automatic spray gantry
US9278367B2 (en) 2012-09-17 2016-03-08 Sunless, Inc. Precision pumping system for spray treatment cycles
US20160108511A1 (en) * 2013-05-06 2016-04-21 Hp Pelzer Holding Gmbh Spray-coating method

Also Published As

Publication number Publication date
BR8904392A (pt) 1990-04-17
NO893140D0 (no) 1989-08-03
AU4109489A (en) 1990-03-29
KR900004410A (ko) 1990-04-12
NO893140L (no) 1990-03-22
CA1336373C (en) 1995-07-25
JPH02135165A (ja) 1990-05-24

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