US3426945A - Apparatus for dispensing adhesive - Google Patents

Description

Feb. 11, 1969 c, HARRMAN 3,426,945 1 APPARATUS FOR DISPENSING ADHESIVE Sheet F1196. June 26 1967 INVENTOR; A//en C. Harri/nan 4%;

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Feb. 11, 1969 A, c. HARRIMAN APPARATUS FOR DISPENSING ADHESIVE Filed Juhe 26, 1967 an 1k E. MM 0 new m FIG-9 FIG-l0 United States Patent Claims ABSTRACT OF THE DISCLOSURE Disclosed herein is a fluid dispenser suitable for use with thermoplastic materials. The device includes a melting chamber in which fluid is stored. The chamber has a base in which a pumping unit is contained, the pumping unit being adapted to pump fluid from the chamber to and out of a discharge orifice. The construction of the pump unit is such that after it causes a predetermined volume of fluid to be dispensed from the discharge orifice some of the residual, undispensed fluid is withdrawn back towards the pump, away from the orifice, thus tending to minimize drip and leakage between dispensing cycles.

SUMMARY OF THE INVENTION The instant invention is directed to an apparatus 101. dispensing a fluid by pumping the fluid through and towards the discharge orifice of a conduit so as to dispense fluid therefrom. The pumping of fluid towards the orifice is then stopped and the flow of fluid in the conduit is reversed so as to withdraw the fluid into the conduit and away from the discharge orifice the effect of which being that the tendency of fluid to drip or leak from the orifice between pumping cycles is minimized.

The apparatus includes a conduit having a discharge orifice at one end thereof, first pumping means associated with said conduit for pumping fluid through said conduit towards and out of said discharge orifice, and a valve disposed along said conduit between said first pump means and said discharge orifice. The conduit is normally filled with fluid, the valve being open, and the first pump means is then operated to cause fluid to be dispensed from the discharge orifice. The valve then is closed to block the conduit and a second pumping means is then operated to draw a portion of the fluid that remained in that portion of the conduit between the valve and orifice back through and out of the conduit so that when the unit is idle, fluid will not be at the tip of the orifice, thus minimizing drip and leakage therefrom. Means are provided for returning the first pump mean-s to its idle position and for refilling the first pump means while the valve is closed and the second pump means is operating.

Th subject of the instant invention may be used in conjunction with any environment in which a fluid, such as molten thermoplastic adhesive, is to be dispensed. By way of example, it may be incorporated into an apparatus such as that disclosed in U.S. patent application Ser. No. 610,097, filed Jan. 18, 1967, in pumping a measured charge of molten thermoplastic adhesive through dispensing outlets disclosed therein onto a shoe part.

The invention will now be described in greater detail with reference to the accompanying drawings wherein:

FIGURE 1 is a plan view of the illustrative embodiment of the instant invention;

FIGURE 2 is a front elevation of the device;

FIGURE 3 is a sectional view of the device taken along the line 33 of FIGURE 1;

FIGURE 4 is a sectional view taken along the line 44 of FIGURE 1;

FIGURE 5 is a plan view in section of the pumping units taken along the line 5-5 of FIGURE 4 and illus 3,426,945 Patented Feb. 11, 1969 trating the position of the members of the pumping units prior to the beginning of the pumping cycle;

FIGURE 6 is a view similar to that of FIGURE 5 illustrating the pumping units with the valves having been rotated to a position wherein fluid may be dispensed from the pumping units;

FIGURE 7 is a view similar to FIGURE 5 illustrating the positions of the members of the pumping units after fluid has been discharged therefrom;

FIGURE 8 is a view similar to that of FIGURE 7 and illustrating the shifting of the valves so as to enable the pumping units to be refilled and to enable the fluid to be withdrawn from the discharge outlet;

FIGURE 9 is a substantially schematic view of the nozble with a portion thereof broken away to illustrate the withdrawal of fluid from the discharge orifice;

FIGURE 10 is a view similar to that of FIGURE 9 illustrating the tendency for fluid to drip from the nozzle; and

FIGURE 11 is a schematic of the control system for operating the pumping unit in the proper sequence.

Referring to FIGURES 1-4, the device includes a pot 10 having a loading chamber 12 and a pump chamber 14. The chambers 12 and 14 are separated by a relatively coarse screen 16 which is secured to upstanding walls 18 that are formed at the interior of the pot 10. A top plate 20 is secured to and covers the pump chamber 14 of the pot 10. A cover 22 overlies the loading chamber 12 and is connected to the top plate 20 by means of a hinge 24 to provide access to the loading chamber 12. A knob 26 is secured to the cover plate 22. In loading the device, the cover 22 is raised and the material to be dispensed, such as a thermoplastic material, is loaded into the loading chamber 12. As may be seen from FIGURES 3 and 4, heaters 28, 30 are provided about the pct 10 to melt the material whereupon it may flow through the screen 16 and into the pumping chamber 14. The screen 16 serves to preclude entry of unmelted large solid particles into the pumping chamber 14.

In the illustrative embodiment of the invention there are two distinct pumping units 32 and 34 (see FIGURES 4 and 5). For the purpose of simplicity of explanation, only the pumping unit 32 will be described in detail, the operation of the other pumping unit 34 being described only to illustrate the differences therebetween. Referring to FIG- UrR'E 3, a plug 36 is disposed within the pump chamber 14 and is secured to the base 38 of the pct 10. A number of conduits 40 are formed within the plug 36 and serve to communicate the pump chamber 14 with the pumping unit 32 that is disposed within the base 38. The pumping unit 32 includes a primary conduit 42 having a first portion 43 and a second portion 44. A rotary valve 46 serves to connect the first and second portions 43 and 44 in a manner later described. A supply conduit 48 which is in communication with the pump chamber 14 by means of the plug 36 is also formed so .as to be in communication with the valve 46. A pair of bores 50 and 52 that intersect respectively, the first and second portions 43 and 44 of the primary conduit 42 are formed within the base 38 of the pot 10. Associated with each of the bores 50 and 52 are the plungers 54 and 56. Each of the plungers 54 and 56 is secured to a piston 58 that is slidable within a counterbore 60, such that movement of each of the pistons 58 along its counter-bore '60 will effect movement of the plungers 54 and 56 axially within their respective bores 50 and 52. Movement of the plungers 54, 56 towards the primary conduit 42 will hereinafter be referred to as forward and movement of the plungers 54, 56 away from the primary conduit 42 will be referred to as rearward.

The rotay valve 46 of the pumping unit 32 is formed at the lower end of a shaft 62 that is rotatable within a bore 64 formed within the base 38 of the pot 10. The

bore 64 is in communication with and connects the portions 48 and 44. The valve 46 comprises a conduit 66 formed along the diameter of the lower part of the shaft 62 and a kenf 68 that is in communication with the conduit 66. The valve 46 is caused to be rotated between two positions, the first of which, illustrated in FIGURE 6, wherein the kerf 68 and conduit 66 of the valve 46 are so aligned as to effect communication between the first and second portions 43, 44 of the conduit 42 with the supply conduit 48 being blocked, and a second position, illustrated in FIGURE 5, wherein the valve 46 has been rotated (clockwise, as seen in FIGURE to effect closure of the passage between the first and second portions 43 and 44 and effect communication between the supply conduit 48 and the second portion 44 of the conduit 42 by means of the kerf 68.

When the pump 32 is in idle position, as illustrated in FIGURE 6, the valve 46 is rotated to its first position and the piston 58 and plungers 54 and 56 are in a rearward position. The first and second portions 43, 44 of the conduit 42 and bores 50 and 52 are filled with molten thermoplastic material, as are the conduit 66 and kerf 68 of the valve 46. The pistons 58 are then urged forwardly, !by means later described, to move the plungers 54 and 56 forwardly within their respective bores 52 and 54 thus pumping the fluid material to the outlet 70 at the end of the first portion 43 of the conduit 42. The fluid that is in the first bore 50 flows out of the first bore 50, into the first portion 43 of the conduit 42, and into a hose 69 that serves as an extension of and is in communication with the first portion 43 of the conduit 42 by means of the fitting 70. At the end of the hose 69 is a dispensing nozzle 71 having a discharge orifice 7 3 through which the fluid is dispensed (see FIGS. 8, 9, By way of example a nozzle of the type disclosed in US. patent application Ser. No. 610,097, filed Jan. 18, 1967 may be used. The fluid in the second bore 52 flows out of the second bore 52 through the second portion 44 of the conduit 42, through the valve 46, into the first portion 43 where it joins the flow from the first bore 50. After the fluid has so been pumped to the nozzle 71, plungers 54 and 56 and valve 46 are in the configuration illustrated in FIG- URE 7.

After completion of the pumping operation, the valve 46 is caused to be rotated to the configuration illustrated in FIGURE 8, from which it may be seen that the kerf 68 serves to communicate the second portion 44 of the conduit 42 and the supply conduit 48, with communication between the first and second portions 43, 44 being blocked. With the valve 46 so rotated, the pistons 58 are caused to be moved rearwardly to their idle positions, as shown in FIGURE 5, to retract the plungers 54 and 56 within their respective bores 50 and 52. Retraction of the plunger 54 is retracted, a portion of the fluid material that is contained within the first portion 43 of the conduit 42, the hose 69 and nozzle 71, and that had not been dispensed the second portion 44 of the conduit 42 and the bore 52, thus refilling this portion of the pump unit 32 in readiness for operation of the succeeding cycle thereof. As the plunger 54 is retracted, a portion of the fluid material that is contained within the first portion 43 of the conduit 42, the hose 69 and nozzle 71, and that had not been dispensed through the nozzle 71, is drawn back through the hose 69 and first portion 43 of the coduit 42 and into the bore 50. The volume of fluid material that is so withdrawn is equal to the displacement of the plunger 54 within the bore 50. The bore 50 thus serves as a storage unit for the withdrawn fluid. Thus, retraction of the plunger 54 will cause a predetermined volume of fluid material to be withdrawn from the discharge orifice 73 of the nozzle 71. It should be noted that when the invention is used with fluids of a relatively high viscosity the tendency for the fluid to drip from the nozzle 71 will be less than if a fluid of lower viscosity is used. For this reason, when using the less viscous fluids the displacement of the plunger 54 should be increased so that a greater volume of fluid will be withdrawn from the discharge orifice 73 of the nozzle 71. The effect of this is to insure that even if there is a tendency for the fluid to flow out of the nozzle the length of time required for the fluid to flow from the point to which it was withdrawn to the outlet of the nozzle will be greater than the time elapsed between operating cycles of the pumping unit 32 so that before the fluid can actually drip from the nozzle the pumping unit 32 is again operated to forcibly and intentionally dispense the fluid. FIGURE 10 is illustrative of fluid beginning to flow from its withdrawn position to the discharge orifice 73 of the nozzle 71. The 'valve 46 may then be rotated to the position shown in FIGURE 6 in readiness for a new cycle of operation.

Referring to FIGURES 1, 2 and 3 the drive means for effecting actuation of the plungers 54 and 56 includes an air-operated motor 72 that is pivotally secured at one end thereof to a bracket 74 which in turn is secured to the frame 76 on which the pot 10 is mounted. The motor 72 has an upwardly extending piston rod 78 and a clevis 80 secured to and extending upwardly from the free end of the piston rod 78. The clevis 80 is pinned to one end of a lever 82, the other end of the lever 82 being secured to a shaft 84 that is rotatably mounted in trunnions 86 that extend upwardly from the top plate 20. Secured to the shaft 84 are a pair of downwardly extending arms 88, the lower ends of which extend into slots 90 formed in the pistons '58. The top plate 20 is provided with slots 92 to enable the arms 88 to extend downwardly therethrough and slots 94 are formed in the base 38 and extend lengthwise of the bores 60 so as to enable the downwardly extending ends of the arms 88 to engage the pistons 58. It may thus be seen that actuation of the motor 72 to lower the piston rod 78 may cause the shaft 84 to rotate (clockwise as seen in FIGURE 3) thus causing the lower ends of the arm 88 to urge the pistons 58 forwardly, thereby effecting forward movements of the plungers 54 and 56 in a pumping stroke. Conversely, upward movements of piston rod 78 will effect a swinging of the arm 88 in a counter-clockwise direction (as seen in FIGURE 3) to retract the pistons 58 and plungers 54 and 56 rearwardly to their normally idle positions. The length of the stroke of the plungers 54, 56 may be varied by means of a stop screw 96 that is adjustably rotatable within the lever 82 and is adapted to abut the head of a bolt 98 fastened to the cover plate 20. The screw 96 serves to limit the extent of movement of the lever 82 and consequently the arm 88 which in turn governs the stroke and displacement of the plungers 54, 56.

The structure and operation of the pump unit 34 is substantially identical to that of the pump unit 32. In the drawings those parts of the pump unit 34 that are substantially identical to and perform the same function as corresponding parts of the pump unit 32 are denoted by identical numerals followed by a prime mark For example, the pistons of the pump unit 32 designated as 58 are referred to in the pump unit 34 as 58. The valve 100 of the pump unit 34 is of slightly different construction than that of the pump unit 32. In the illustrative embodiment of the invention this is necessitated as a result of the particular drive mechanism utilized to effect rotation of the valves 46 and 100. The mode of operation and function of the valves 46 and 100, however, is the same.

The rotation of the valves 46 and 100 is effected by means of an air-actuated motor 102 that is pivotally connected to the bracket 74 and has an upwardly extending piston rod 104 the end of which is pivotally connected to one end of a bell crank lever 106. The *bell crank lever 106 is pivotally mounted on a bracket 108 that is secured to the top plate 20 (see FIGURES l, 2, and 3). The other end of the bell crank lever 106 is pivotally connected to the end of a forwardly extending rod 110. The other end of the rod 110 is pivotally connected at the pivot pin 112 to the ends of actuating levers 114 and 114'. The actuat ing lever 114 is secured to the upper end of the cylinder 62 and the actuating lever 114 is secured to the upper end of the cylinder 62 which is journaled for rotary movement in the top plate by means of bearings 116. It may thus be seen that when the piston rod 104 of the motor 102 is urged upwardly the shafts 62 and 62 Will be rotated to a position wherein the valves 46 and 100 that are formed integrally with the bottom portions of the cylinders 62, 62' are in to their first position as illustrated in FIGURE 6. Conversely, when the piston rod 104 of the motor 102 is urged downwardly the valves 46 and 100 will be rotated to their aforesaid second position illustrated in FIGURE 5. It should be noted that the cylinders 62 and 62' and consequently the valves formed therein rotate in opposite directions; that is, when the valves 46 and 100 rotate from their first position to their second position the valve 46 rotates clockwise, whereas the valve 100 rotates counter-clockwise as seen in FIGURE 5. Conversely, when the valves are rotated from their second to their first positions the valve 46 rotates counter-clockwise and the valve 100 rotates clockwise.

The difference in directions of rotations of the valves 46 and 100 necessitates a different configuration in the passageways of the valves 46 and 100*. Thus the kerf 118 of the valve 100 although serving the same purpose as that of the kerf 68 of the valve 46 does not intersect the passageway 120 formed in the valve 100.

Referring again to the pumping unit 32, when it is in an idle position and in readiness to pump fluid material therefrom the fluid material contained within the first portion 43 of the conduit 42 does not extend to the tip of the outlet 70, the volume which is unoccupied by the fluid being equal to the volume of fluid that had been withdrawn during the previous cycle of operation by means of rearward movement of the plunger 54 within the bore 50. Thus in order to dispense a predetermined volume of fluid from the nozzle 71 the volume of fluid that is pumped through the first portion 43 of the conduit 42 must be equal to that volume which is desired to be discharged plus the volume which had been previously withdrawn. The plunger 54 and bore 50 supply the volume of fluid necessary to completely fill the first portion 43 of the conduit 42 and the plunger 56 has a displacement equal to the volume of the fluid that is to be discharged from the orifice 73. Thus the displacement of the plunger 54 governs the extent of withdrawal of fluid within the first portion 43 of the conduit 42 and the displacement of the plunger 56 governs the volume of fluid that is actually dispensed from the orifice 73 of the nozzle 71.

Actuation of the motors 72 and 102 to operate respectively the plungers 54, 56 and the rotary valve 46 in the aforementioned sequence is effected by a pneumatic circuit ilustrated schematically in FIGURE 11. A source of compressed air S is connected by means of the line 122 to the inlet of a valve 124. The outlet of the valve 124 is connected by means of the line 126 and the line 128 to the rod end of the motor 72. The head end of the motor 102 is also connected to the outlet of the valve 124 by means of the line 126 and line 130. A restriction 132 is provided in the line 128 for restricting the flow of air therethrough to the motor 72. It may thus be seen that when the valve 124 is shifted from its normally closed position to a position wherein compressed air may flow from the source S thereof through the line 122, the valve 124, the line 126 and then into both of the lines 128 and 130 to urge the piston rod 78 of the motor '72 downwardly thereby urging the plungers 54, 56' forwardly in a pumping stroke and urging the piston rod 104 of the motor 102' upwardly to cause the valve 46- to shift to its second position wherein the aforementioned pumping stroke is permitted. The restrictor valve 132 located in the line 128 insures that the motor 102 will be actuated before actuation of the motor 72 so that the valve 46 will have been rotated to its second position before initiation of the pumping stroke. After the pumping stroke has been completed and the fluid has been dispensed from the discharge orifice 73 of the nozzle 71 the motors 72 and 102 are reversed to rotate the valve 46 to its first position thus enabling the withdrawal of fluid from the discharge orifice 73 of the nozzle 71 and the refilling of the pump unit 32 for a succeeding cycle of operation. The reversal of the motors 72 and 102 is effected by means of flow of compressed air from the source S through the line 134, the valve 136, the line 138 and into the line 140 which is connected to the head end of the motor 72 and into the line 142 which isconnected to the rod end of the motor 102. The valve 136 which is normally closed is actuated by a cam. or other suitable means to enable the compressed air to follow the aforementioned path into the lines 140 and 142 to cause the piston rod 104 of the motor 102 to be retracted downwardly thereby rotating the valve 46 to its first position and causing the piston rod 78 of the motor 72 to be urged upwardly thereby drawing the plungers 54, 56 rearwardly. A restrictor valve 144 is located in the line 140 to insure that the motor 72 is not actuated until after the motor 102 has been actuated and the valve 46 has been rotated to its first position. Each of the valves 124 and 136 are of such construction that air that is exhausted from either end of either motor may flow through the lines associated therewith and to its associated valve and be exhausted to the atmosphere.

The foregoing disclosure is to be understood as defining only an illustrative embodiment of the invention, the scope of which is defined in the appended claims.

-I claim:

1. A fluid dispensing system comprising: a source of fluid; a primary conduit having a discharge orifice, a first portion and a second portion, the first portion being between the discharge orifice and the second portion; a first fluid storage unit in communication with said first portion; a second storage unit in communication with said second portion; a movable valve in the primary conduit, located between said first and second portions, so constructed as to permit communication between said portions when in a first position and to block communication between said portions when in a second position; means providing communication between the source and the second storage unit when the valve is in said second position; means for initially maintaining the valve in said first position with the primary conduit and the storage units filled with fluid; means for thereafter forcing the fluid from both storage units into the primary conduit to thereby dispense fluid from the discharge orifice; means for thereafter moving the valve from its first position to its second position; and means for thereafter drawing fluid from the primary conduit into the first storage unit and for drawing fluid from the source into the second storage unit.

2. The system as defined in claim 1 wherein said first storage unit comprises: a first bore in communication with said first portion; and a first plunger mounted in the first bore for movement between a rearward position remote from said first portion and a forward position that is closer to said first portion; wherein said second storage unit comprises: a second bore in communication with said second portion; and a second plunger mounted in the second bore for movement between a rearward position that is remote from said second portion and a forward position that is closer to said second portion; wherein both plungers are initially maintained in their rearward positions; wherein said means for forcing the fluid from both storage units into the primary conduit comprises means for moving both plungers from their rearward to their forward positions; wherein the means for drawing fluid from the primary conduit into the first storage unit comprises means for moving the first plunger from its forward position to its rearward position; and wherein the means for drawing fluid from the source into the second storage unit comprises means for moving the second plunger from its forward position to its rearward position.

3. The system as defined in claim 1 further comprising:

a supply conduit connecting the source and the valve; and wherein said valve is so constructed as to permit communication between the supply and the second storage unit when the valve is in said second position to thereby constitute said means providing communication between the source and the second storage unit.

4. The system as defined in claim 1 further comprising:

a supply conduit connecting the source and the valve; wherein said first storage unit comprises: a first bore in communication with said first portion; and a first plunger mounted in the first bore for movement between a rearward position remote from said first portion and a forward position that is closer to said first portion; wherein said second storage unit comprises: a second bore in communication with said second portion; and a second plunger mounted in the second bore for movement between a rearward position that is remote from said second portion and a. forward position that is closer to said second portion; wherein said valve is to constructed as to permit communication between the supply and the second bore when the valve is in said second position to thereby constitute said means providing communication between the source and the second storage unit; wherein both plungers are initially maintained in their rearward positions; wherein said means for forcing the fluid from both storage units into the primary conduit comprises means for moving both plungers from their rearward to their forward positions; wherein the means for drawing fluid from the primary conduit into the first storage unit comprises means for moving the first plunger from its forward position to its rearward position; and wherein the means for drawing fluid from the source into the second storage unit comprises means for moving the second plunger from its forward position to its rearward position.

5. A fluid dispensing system comprising:

a base member;

a primary conduit formed within said base member and having a discharge orifice formed at one end thereof;

a. supply conduit formed within said base member, said supply conduit having one end thereof in communication with said primary conduit at a common juncture intermediate the ends of said primary conduit and the other end thereof adapted to be in communication with a source of fluid;

a first bore formed within said base member and being in communication with the other end of said primary conduit;

a first plunger slidably contained for reciprocating movement within said first bore so as to be capable of pumping fluid into and out of said other end of said primary conduit;

valve means disposed at said common juncture and being operable between a first position wherein communication is established between said other end of said primary conduit and said discharge orifice while communication between said supply conduit and said common juncture is blocked and a second position wherein communication between said other end of said primary conduit and said discharge orifice is blocked and communication between said supply conduit and said other end of said primary conduit is established;

a second bore formed within said base member and being in communication with said primary conduit at a point intermediate said discharge orifice and said common juncture;

a second plunger slidably contained for reciprocating movement within said second bore so as to be capable of pumping fluid into and out of said one end of said primary conduit;

means for operating said first and second plunger, while said valve means is in said first position, so as to cause fi-uid to be pumped into said primary conduit and out of said discharge orifice;

means for thereafter switching said valve to said second position thereof; and

means for thereafter operating said first and second plungers to pump fluid out of said primary conduit whereby at least a portion of the fluid contained within that portion of said primary conduit between said orifice and said common juncture may be withdrawn into said second bore and fluid may be caused to flow from said supply thereof, through said supply conduit, through said valve, through said other end of said primary conduit and into said first bore.

References Cited FOREIGN PATENTS 482,247 4/ 1952 Canada.

SAMUEL F. COLEMAN, Primary Examiner.

US. Cl. X.R.

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