Modular Solenoid-operated Dispenser

Abstract

A solenoid-operated dispenser for dispensing liquid materials. The dispenser comprises a heated service module which contains static parts, a gun module which contains all of the movable parts of the dispenser, and a solenoid coil module, all three modules of which are resiliently held in an assembled relationship by a single threaded nut.

Description

This invention relates to a dispenser or a gun for dispensing liquids in the form of beads, ribbons, or stripes in a desired pattern under high speed production conditions. More particularly, the invention relates to equipment for applying molten adhesives or so-called "hot melts" to substrates used in packaging, sealing or assembling a variety of products.

Liquid adhesives, or so-called "hot melts," are commonly used where there is a need for a very short setting time for the material to set up and bond together two parts of a package or two parts of an assembly. Typically, they are solid at room temperature and must be heated before they become molten so that they can be supplied to and dispensed from a gun. When heated to molten form, the materials change to a relatively viscous liquid which may be supplied to a dispensing gun at a relatively high pressure and then dispensed from the nozzle of the gun in the form of a continuous bead or ribbon or an intermittent deposit. The flow of material from the gun is controlled by a valve located internally of the gun adjacent the nozzle orifice.

A common production problem encountered with hot melt dispensing guns in high production facilities is that of interrupting the production facility for relatively long periods of time in order to clean the gun of hot melt material which has become lodged therein or to replace worn out parts. Generally, cleaning requires disconnection of the service lines, including the electrical service lines to the heater of the gun, disconnection of the liquid supply lines for supplying the molten material to the gun, and disconnection of the power lines for operating the gun. If the gun is a pneumatically operated gun, the power line is an air line to the gun; and if the gun is solenoid-operated, the power line is an electrical one. After disconnection of all lines, the gun generally must be broken apart in order to disconnect it from its mounting so as to enable a new or clean gun to replace it. All of this disconnection and disassembly is generally time consuming and expensive because of the resulting loss of a production facility on which the gun is one relatively small component.

In U.S. Pat. No. 3,570,725 issued Mar. 16, 1971, and assigned to the assignee of this application, there is disclosed a modular type of pneumatically operated gun in which the gun may be removed from a service module as a separate unit and replaced without any time-consuming disconnection of the service lines and disassembly of the gun. That modular gun has been well received in hot melt production facilities and has eliminated many of the problems set forth hereinabove. There is still, though, a need for a solenoid-operated modular gun to accomplish the same objectives and eliminate the time-consuming disassembly and reassembly problem normally associated with the cleaning and replacement of solenoid-operating hot melt dispensing guns in high speed production facilities.

It has therefore been one objective of this invention to provide a modular solenoid-operated dispensing system in which the gun portion of the dispenser may be easily and quickly replaced in the event that the gun portion needs to be cleaned or a component needs to be replaced.

Still another object of this invention has been to provide a solenoid-operated dispensing apparatus for dispensing hot melt or viscous liquids in which the solenoid coil of the gun may be easily and quickly replaced in the event that it fails while the remainder of the gun and system is fully operative.

The invention of this application which accomplishes these objectives comprises a three-module dispensing apparatus made from a service module, a gun module, and a solenoid module. All three modules are resiliently held in an assembled relation by a resilient washer and a single threaded connector. The service module houses all of the essentially static components of the dispenser and includes an electrical heater for heating the service module and subsequently transmitting heat through contacting surfaces to the gun module so that the molten material contained in the gun remains in the molten state. The gun module contains all the movable components of the dispensing apparatus and is generally tubular in configuration. Over this tubular gun module the solenoid coil module is mounted and is resiliently held in an assembled relation by a resilient washer and a single threaded connector which also holds the gun module mounted within an aperture of the service module.

The primary advantage of this modular construction of solenoid-operated dispenser is that it enables the solenoid module to be quickly replaced in the event that it fails or the gun module to be easily and quickly replaced in the event that it becomes clogged or breaks down because of excessively worn parts. After replacement of a worn or clogged gun with a new clean one, or replacement of a failed coil, the failed gun or solenoid coil may be torn down and rebuilt without interruption of a production facility upon which the gun or coil had previously been in use. This construction also has the advantage of facilitating repair and cleaning of the dispensing apparatus.

These and other objects and advantages of this invention will be more readily apparent from the following description of the drawings illustrating one preferred embodiment of the invention in which:

FIG. 1 is an exploded perspective view of a dispensing apparatus incorporating the invention of this application; and

FIG. 2 is a cross sectional view of the apparatus.

Referring to FIG. 1, it will be seen that the dispenser 10 of this application is assembled from three modules which are easily assembled and disassembled for purposes of cleaning or repairing the unit. Specifically, this dispenser 10 comprises a service module 11, a gun module 12, and a solenoid coil module 13. These three modules are all resiliently held in an assembled relation by a resilient washer 14a and a single nut 14 threaded over one end 15 of the gun module 12, as is explained more fully hereinafter.

The service module 11 serves as a mounting block for the gun and solenoid coil modules as well as for an electrical control enclosure 16. This service module 11 is generally fixedly mounted, by a means not shown, upon a slide block or some other fixed fastening located in a predetermined location relative to a substrate upon which molten liquid material is dispensed from the gun.

The service module is comprised of a stepped block 17 which has two vertical bores through it. One of these bores 18 is counterbored and is adapted to receive an electric heating element 19. The other bore receives and supports the gun module 12.

Electrical power to the coil 20 of the solenoid 13 is supplied via electrical leads 21 which are housed within the conventional electrical enclosure or so-called junction box 16. This box is fixedly mounted upon the top of the service module block 17. The enclosure within the box 16 also houses an electrical thermostat 22 which controls the flow of electric power to the heater 19 and consequently determines the temperature of the block 17. Heat from the block 17 in turn is transmitted through the contacting surfaces of the service module block 17 and the gun module into molten material contained interiorly of the gun.

The gun module 12 comprises a cylinder assembly 30, a nozzle assembly 31, a valve 32 for controlling the flow of pressurized molten material from the nozzle 31, and a valve plunger 33 for controlling actuation of the valve 32.

The cylinder assembly is made from four components, all of which are brazed together to form a sealed and joined unit. These components comprise an annular flange 35, a spring chamber sleeve 36, a non-magnetic plunger guide sleeve 37, and a magnetic inlet fitting 38. The spring chamber sleeve 36 has a through bore 40 which is counterbored at the lower end and provides a large open chamber for the reception of a valve control spring 41. This bore 40 is also counterbored at its upper end, as indicated at 42, so as to provide a seat for the lower end of the plunger guide sleeve 37. At its upper end, the plunger guide sleeve 37 receives the lower end 45 of the molten material inlet fitting 38. There is preferably a conventional copper shading ring 46 mounted within an annular recess machined from the lower end of the inlet fitting 38. The upper end 15 of the inlet fitting is externally threaded for reception of a resilient washer 14a and the nut 14 which resiliently holds the three modules in an assembled relation, as is explained more fully hereinafter.

The nozzle assembly 31 of the dispensing gun is conventional and comprises a radially flanged gun seat through which there extends an axial bore 50. This axial bore is counterbored so that the lower small diameter end section may receive and be brazed to a carbide valve seat 51. The radial flange 53 of the nozzle gun seat is bolted to the flange 35 of the cylinder assembly by machine screws 55. There is preferably a metal O-ring 56 located between the lower end of the cylinder assembly and the flange 53 of the nozzle gun seat to prevent leakage of molten material between the two.

The valve of the gun is formed by an axial needle 57, the lower end of which terminates in a semispherical end 58 which seats over and closes an axial passage 59 of the valve seat 51. This passage 59 is counterbored and fluted so that molten material may flow around the needle within the larger upper end section of the bore.

At its upper end, the needle 57 is externally threaded and is received within an internally threaded bore 65 of the plunger 33. A lock nut 66 secures the needle in an axially adjusted position within the plunger.

Intermediate its ends, the needle supports a spring collar 70. This collar has a central hub 71 threaded over the threaded section of the needle and four arms 72 which extend radially from this hub 71 and support the lower end of the compression spring 41. At its upper end this spring rests against a shoulder 73 in the bore 40 of the spring chamber sleeve 36. There is preferably a lock nut 75 threaded over the needle to lock the spring collar 70 in an adjusted position.

The plunger 33 is made from a magnetic stainless steel or other ferrous material so that it acts as the armature of the solenoid coil 20 within the cylinder. A gap 80 between the lower end of the inlet fitting 38 and the top surface of the plunger 33 permits the plunger to be moved upwardly by magnetic flux of the solenoid coil 20. When the plunger is in its uppermost position, the valve 32 is open so that pressurized molten material contained within the valve chamber 50 may exit through the passage 59.

In order for the molten material supplied to the gun via the inlet fitting 38 to flow through the axial passage 81 of the fitting 38 downwardly to the valve chamber 50, there are four radial grooves 84 and four intersecting longitudinal grooves 85 machined from the surface of the plunger. The radial grooves 84 in the top surface of the plunger are axially aligned with and intersect the longitudinal grooves 85 in the peripheral surface of the plunger so that each groove forms a continuous flow path along the exterior of the plunger from the lower end of the passage 81 into the spring chamber 40 of the sleeve 36 and subsequently into the valve chamber 50 of the nozzle gun seat 34.

The solenoid coil module 13 comprises a tubular spool 90 of Teflon or a similar dielectric material upon which the wire of the coil 20 is wound. The ends of this wire terminate in the leads 21 which extend into the electric enclosure 16. A magnetic metal casing completely encloses the coil 20 and spool 90. This casing comprises a steel sleeve 91 over which there is fitted a steel cap 92 and a lower flux retainer disc 93. The disc 93 and the sleeve 91 both have a cutout recess 94, 95 on one side through which the leads 21 extend.

The lower retainer flux ring 93, the sleeve 91, and the cap 92 are all sealed and permanently joined together around the coil 20 so as to form a complete subassembly which may be assembled over the cylinder of the gun or removed therefrom as a complete unit. This module 13 is held in an assembled relation over the barrel of the gun module 12 by the nut 14 threaded over the end 15 of the fitting 38 and the resilient washer 14a. The purpose of the resilient washer 14a is to accommodate relative thermal deflections among the service module 11, the gun module 12, and the solenoid module 13.

In operation, if the gun should become clogged or should fail for any reason, all that is required to remove it from the service module 11 so as to permit its replacement on the service module is to remove the nut 14 and resilient washer 14a from over the inlet fitting of the gun barrel. Upon removal of this nut and washer, the complete gun module 12 may be dropped downwardly through the bore 96. The coil will automatically be removed from over the barrel as a consequence of this disassembly. Alternatively, if the coil should fail, all that is required to remove it is to remove this same nut 14 and resilient washer 14a and lift them from over the cylinder. In this way the solenoid coil module may be replaced or the gun module may be replaced with a minimum of lost production time. After the gun module or the solenoid module has been removed from the service module, it may be cleaned or disassembled while the production line upon which it had previously been operating continues to function.

It is to be noted that in addition to the removability of the solenoid module 13 and/or the gun module 12 by simply unthreading and removing the nut 14 from over the threaded section 15 of the gun inlet fitting 38, the internal mechanism of the gun may be removed from the barrel while the nut 14 retains the solenoid and the gun barrel in an assembled relation on the service module 11. This type of disassembly is sometimes desirable if the spring 41 should become broken or if the gun should become broken or clogged at the valve seat. In that event, all that is required is to remove the bolts 55 and drop the nozzle assembly 31 together with the needle 57, the spring 41, and the plunger 33. Any one of these components may then be replaced or repaired and the unit reassembled with a minimal loss of production time.

It is also to be noted that when one gun replaces another, there is no alignment problem associated with properly locating the nozzle relative to the substrate upon which it is intended to dispense molten material. As a consequence of having the service module fixed relative to that substrate, the dispensing guns automatically become properly aligned when located in the service module.

While we have described only a single preferred embodiment of our invention, persons skilled in this art will appreciate changes and modifications which may be made without departing from the spirit of our invention. Therefore, we do not intend to be limited except by the scope of the following appended claims.

Claims

1. Apparatus for dispensing a liquid from a pressurized source comprising

a service module having essentially only static parts, said service module including a mounting block having a gun module contacting surface of substantial area, said mounting block being adapted to be secured to a support,

a readily removable gun module attachable to and mountable upon said service module mounting block, said gun module including essentially all of the movable parts of said dispensing apparatus, said gun module including a discharge nozzle and a valve for controlling flow of viscous liquid from said nozzle, said gun module further including a cylinder and a movable plunger mounted within said cylinder, said plunger being operatively connected to said valve so as to effect opening and closing of said valve upon actuation of said plunger, said gun module having a service module mounting block contacting surface of substantial area,

heater means contained within said service module for heating said service module mounting block, said service module mounting block being operable to transmit heat through said contacting surface into said gun module so as to heat liquid contained within said gun module, and

a solenoid coil module mounted over said cylinder of said gun module, said solenoid coil module including an electrical solenoid coil for controlling movement of said plunger within said cylinder,

said solenoid coil module being removable and replaceable on said dispensing apparatus without disassembly of said gun module and said gun module being removable and replaceable on said service module without disassembly of said gun module,

said solenoid coil module and said gun module being jointly secured to said

2. The dispensing apparatus of claim 1 in which said heating means is an electrical heater mounted within said service module mounting block, said service module further including a thermostat for controlling the flow of

3. The dispensing apparatus of claim 2 in which said service module mounting block has an aperture therein for the reception of said gun module, said gun module being mounted within said aperture, with at least a portion of said cylinder extending outwardly from said aperture, said solenoid coil module being mounted over said cylinder outwardly of said

4. The dispensing apparatus of claim 3 in which said solenoid coil module and said gun module are jointly secured to said service module mounting

5. The dispensing apparatus of claim 1 in which said gun module further includes a liquid inlet fitting axially aligned with and secured to said cylinder, and liquid passage means extending from said inlet fitting through said plunger into a valve chamber located interiorly of said gun

6. Apparatus for dispensing a viscous liquid from a pressurized source comprising

a service block module having essentially only static parts, said service block module including a mounting block adapted to be secured to a support, heating means contained within said service module mounting block,

a readily removable gun module attachable to and mountable upon said service module mounting block, said gun module including essentially all of the movable parts of said dispensing apparatus, said gun module including a discharge nozzle, a valve for controlling flow of viscous liquid from said nozzle, and spring means for biasing said valve to a closed position, said gun module further including a cylinder and a movable plunger mounted within said cylinder, said plunger being operatively connected to said valve so as to effect opening and closing of said valve upon actuation of said plunger,

a solenoid coil module mounted over said cylinder of said gun module, said solenoid coil module including an electrical solenoid coil for controlling movement of said plunger within said cylinder, and

a single threaded connector for jointly securing said solenoid coil module

7. The dispensing apparatus of claim 6 in which said service module mounting block has an aperture therein for the reception of said gun module, said gun module being mounted within said aperture, with at least a portion of said cylinder extending outwardly from said aperture and said solenoid coil module being mounted over said cylinder outwardly of said

8. The dispensing apparatus of claim 7 in which said gun module further includes a liquid inlet fitting axially aligned with and secured to said cylinder, and liquid passage means extending from said inlet fitting through said plunger into a valve chamber located interiorly of said gun module.