US3394888A - Dispensing gun - Google Patents

Description

JulyO, 1968 L. F. DASSE ET AL 3,394,888

DISPENSING GUN Filed March '7, 1967 3,394,888 DISPENSING GUN Lester F. Dasse, St. Joseph, and Richard J. Ott, New Buffalo, Mich, assignors to Respond Inc., Baroda, Mich., a corporation of Michigan Continuation-in-part of applications Ser. No. 374,438, June 11, 1964, and Ser. No. 540,874, Apr. 7, 1966. This application Mar. 7, 1967, Ser. No. 621,241

Claims. (Cl. 239-424) ABSTRACT OF THE DISCLOSURE The dispensing gun disclosed is especially suitable for spraying lubricants onto surfaces of die casting diesv Particular dimensional relationships between elements within the spray nozzle are set forth. An adjustable check valve is positioned for controlling the rate at which the lubricant or fluid is dispensed.

Specification This application is a continuation-in-part of applications Ser. No. 374,438 filed June 11, 1964 now abancloned, and Ser. No. 540,874 filed Apr. 7, 1966.

While certain features of the present invention are adaptable for use in a wide variety of installations for performing different functions, one use for which spray guns incorporating features of the present invention are especially suitable is the spraying of lubricants onto surfaces of die casting dies. For such use, the spray head should be able to spray effectively a wide variety of materials ranging from low viscosity hydrocarbons and water soluble lubricants to high viscosity materials including slurries of mixtures of heavy oils loaded with particles of aluminum pigment or graphite in flaked form.

Heretofore suggested spray heads which have been proposed for use in connection with a die casting operation have usually been constructed so as to require the lubricant to be forced through the nozzle under relatively high pressure and introduced into an air stream which is delivered at a similar or only relatively slightly higher pressure, and such heretofore suggested spray heads usually incorporate needle valve adjustments, elastomeric seals and various combinations of relatively moving elements which require expensive machine finishes and close tolerances in order to perform. As a result, such heretofore proposed spray heads have been very expensive and have required frequent removal for cleaning and repair so that a die caster may suffer substantial losses as a result of down time. Prior to the present invention it was found that down time caused by maintenance was one of the most important factors causing die casters to delay in or refrain from automating their die casting machines.

It is an important object of the present invention to provide a novel dispensing gun or spray head which is relatively inexpensive to manufacture and maintain and which is highly reliable.

Another object of the present invention is to provide a novel spray gun which is of relatively simple construction and which does not require expensive machining or the holding of close tolerances while still being capable of delivering a spray reliably and relatively uniformly and in finely divided particles.

Still another important object of the present invention is to provide a novel dispensing gun or spray head of the above-described type which is capable of efiiciently and reliably spraying a wide variety of materials such as those used as die casting lubricants and which is capable of functioning properly with significantly reduced States Patent 0 "ice maintenance and down time costs in a relatively hostile environment such as is present in the vicinity of die casting dies.

A further object of the present invention is to provide a novel dispensing gun or spray mechanism capable of selectively delivering a blast of air and a mixture of air and liquid whereby the gun may be selectively used for such purposes as spraying a lubricant on a die casting die and for cooling the die by a blast of air.

Another object of the present invention is to provide a novel spray gun utilizing air under pressure for spraying a liquid or the like and incorporating simple, economical and effective means for controlling the rate at which the liquid is dispensed substantially independently of the air under pressure.

Still another object of the present invention is to provide a novel spray gun of the above described type capable of projecting a spray or jet of lubricant in a desired pattern for a relatively great distance in order to promote proper and uniform coating of die casting dies and the like and to enable the lubricant to be projected into relatively deep cavities in such dies.

Other objects and advantages of the present invention will become apparent from the following description and the accompanying drawings wherein:

'FIG. 1 is a perspective view showing a dispensing gun or spray head incorporating features of the present invention and further schematically showing the dispensing gun connected with sources of air under pressure and liquid to be dispensed;

FIG. 2 is an enlarged fragmentary partial sectional view taken generally along line 22 in FIG. 1;

FIG. 3 is a perspective view similar to FIG. 1 but shows a slightly modified form of the present invention; and

FIG. 4 is an enlarged fragmentary partial sectional view taken generally along line 4-4 in FIG. 3.

Referring now more specifically to the drawings wherein like parts are designated by the same numerals throughout the various figures, a spray head 10 incorporating features of the present invention is shown in FIGS. 1 and 2. In this embodiment the spray head is supported by any suitable means 12 and is connected by a line 14 with a source 16 of air under pressure. The spray head is also connected by a line 18 with a source 20 of liquid 22 to be sprayed.

Air may be delivered from the source 16 under any desired pressure and may, for example, be delivered at about p.s.i. A valve 24 is connected in the air line 14 'and is adapted to be actuated by a solenoid or other suitable control means 26 for starting or stopping the flow of air, as desired.

The source 20 of liquid may comprise a pressurized chamber or any other suitable means for delivering the liquid under a relatively low pressure to the spray gun. This pressure need be only suflicient to overcome frictional losses in the line 18 and the static head which may exist if the spray gun 10 is located above the source 20'. As examples only, the pressure applied to the liquid may be on the order of 10 to 30 p.s.i. In other words, with air pressures of the magnitude previously indicated, the liquid pressure at the source would be only about 10% to 30% of the air pressure. A check valve 28 is provided in the liquid line 18 to resist draining of the line between the gun and the reservoir 20.

The spray head 10 comprises a main body member 30 having an enlarged chamber 32 formed in one end portion thereof and defined by a cylindrical wall 34. A nozzle element 36 is threaded into an end portion of the cham- 'ber 32 as at 38. An inner end of the nozzle member 36 is formed with a tapering or flaring passageway portion 3 40 forming a restricted Venturi throat and merging with a discharge passageway 42 which is of substantially uniform diameter as will be described more in detail below.

The high pressure air line 14 communicates with an inlet port 44 in the body member 30, which port in turn communicates with the chamber 32. The liquid supply line 18 is connected with a fitting 46 threaded or otherwise secured in an opening 48 formed in the body member 30, which opening communicates with a chamber 50. The fitting 46 provides an inlet port 52 having an inner end defined by a valve seat 54 which is engaged by a ball valve element 56 disposed in the chamber 50. As will be discussed more in detail below, the ball 56 serves as a check valve to retain liquid in the spray head at the end of a spray operation. Movement of the ball is also adjustably controlled so as to provide simple yet highly effective means for controlling the rate of flow of the liquid through the spray head.

In this embodiment a spring 58 is positioned in the chamber 50 for engagement with the ball 56 and yieldably urges the ball against the seat 54. In addition, a screw 60 is threaded through the body member 30 so as to project into the chamber 50 with an end 62 thereof positioned adjacent the ball 56. The end 62 provides a rigid abutment positively limiting the distance which the ball 56 may lift above the seat 54. The ball thus serves to restrict free flow of the fluid through the inlet port 52 and thereby controls the rate at which the liquid may be dispensed by the spray gun. The screw 60 has an enlarged head 64 at its outer end for facilitating adjustment. A nut 65 releasably secures the screw in the desired position. Adjustment of the screw toward and away from the ball also adjusts the positive abutment 62 and the distance which the ball can lift from the seat. In other words, the rate at which liquid may be discharged can be adjusted by turning the screw 60 and adjusting the position of the positive abutment 62.

Passageway means is provided through the body 30 for directing liquid from the chamber 50 to the discharge nozzle member passageway 42. The passageway means comprises a bore 66 formed in the body member 30 and extending from the chamber 50. In addition, a tube 68 has one end mounted in a seat or counterbore 70 in the body member and an opposite end 72 concentric with and positioned in the nozzle passageway 42. The tube 68 has an internal diameter substantially equal to the diameter of the passage 66 except that a short outlet end portion 74 is preferably cut away or beveled so that the end 72 of the tube presents a relatively thin edge which promotes mixing of the liquid with the air.

While the previously described parts of the spray gun do not require expensive machining or the holding of close tolerances, certain other relationships between parts are necessary to assure maximum efficiency and proper uniform atomization of the liquid material being sprayed. More specifically, the area of the passageway 42 transverse ctross-section A1, is related to the tube 68 outside diameter transverse cross-sectional configuration A2 for providing a restriction or a restricted throat R determined in accordance with the formula The cross-sectional area of the inlet port 44 into the head chamber 32 is preferably at least substantially equal to or greater than twice the area of the restriction R.

Another relationship which must be substantially maintained pertains to the position of the tubing end edge 72 within the passageway 42. This passageway has an overall axial length L11 between its junction 76 with the conical surface 40 of the Venturi and the outer end 78 of the nozzle. The tube is positioned so that the distance L2 between the end edge 72 of the tube and the outer end 78 4 of the nozzle is related to the distance or length L1 in accordance with the formula Experiments has shown that changes in the position of the tubing will greatly affect the efiiciency of the spray head. For example, varying the position of the tubing as much as plus or minus one-eighth inch, has caused variations of 30% to 40 in the suction applied at the end of the tubing when using air at 100 p.s.i. It has further been found that the basic nozzle dimensions may be increased or decreased, but the aforesaid relationships must be maintained for maximum efiiciency.

When operating the spray head, the air valve 24 is opened so as to admit air under relatively high pressure to the chamber 32 in the spray gun. The air then flows through the restriction or throat means R and out through the passageway 42 so that an area of reduced pressure or suction is created at the end 72 of the tube 68. This suction, of course, is transmitted through the tube and the passageway 66 to the chamber 50 so that the ball 56 is lifted against the action of the spring 58. In addition the liquid which is supplied to the conduit 18 at a relatively low pressure as indicated previously herein is drawn upwardly to the inlet port 52. The position of the ball 56 which is determined by the stop 62 restricts the inlet port 52 in a manner so as to control the rate at which the liquid can fiow therethrough. At the same time the rounded surface of the ball provides a deflecting surface or means for spreading the liquid radially around the chamber 50 for aiding in breaking up the flow of the liquid and facilitating free passage of the liquid through the chamber 50, the tube 68 and atomization of the liquid as it emerges from the tube into the air stream in the passageway 42. .As previously indicated, the rate at which the liquid is discharged can be varied by adjusting the screw 60 and thereby adjusting the distance which the ball 56 is permitted to lift from the valve seat 54. The screw 60 may even be tightened sufiiciently to secure the ball 56 in the closed position in the event it is desired to discharge an air blast without spraying liquid.

In FIGS. 3 and 4 there is shown a slightly modified form of the present invention which is essentially identical to the structure described above and as indicated by the application of identical reference numerals with the sufiix a added to corresponding parts. This embodiment differs in that the spray gun 10 is especially adapted to be held in the hand of an operator. Thus, a hand grip member 80 is connected to the body member 30. In the embodiment shown, the air and fluid conduits or lines 14a and 18a comprise flexible hoses in order to permit an operator to manipulate the gun. The line 18a is connected with the grip member 80 which has a passageway 82 extending therethrough and communicating with the inlet port 52a.

The construction or arrangement of the interior of the spray head 10a including the air and liquid passageways, ports, valves and the like are identical to those described above except that the spring for urging the ball element 56a against the seat may be omitted. In fact, the spring may be omitted from the previously described embodiment if desired, but such omission may be undesirable in many installations since the ball valve element might not seal sufficiently against the valve seat when operation of the gun is discontinued to prevent either the liquid from draining back in the supply line 18 or preventing the liquid from being forced out through the gun in the event a slight pressure is maintained in the line as indicated hereinabove.

When the spring is omitted from the gun as indicated above, draining of the liquid supply line may be prevented by providing a check valve assembly 84 in the liquid supply reservoir 20a as shown in FIGS. 3 and 4.

In this embodiment the check valve assembly has a main body 86 with fiuid inlet means 88 and 90 communicating with a valve seat 92 against which a ball valve element 94 is urged by a compression spring 96. The liquid supply source 20a may be pressurized or, in many installations, and particularly for hand operations, the reservoir need not be pressurized and the suction created within the nozzle will be suflicient to draw the liquid from the reservoir to the spray head.

While preferred embodiments of the present invention have been shown and described herein, it is obvious that many structural details may be changed without departing from the spirit and scope of the appended claims.

The invention is claimed as follows:

1. A spray gun comprising body means, first and second inlets into said body means respectively for air under pressure and for a material to be sprayed, first and second chambers in said body means respectively communicating with said first and second inlets, an outlet passageway having a predetermined length between inner and outer ends and a predetermined cross-sectional area and communicating with said first chamber, tube means communicating with said second chamber and having a terminal end located within said passageway, said tube means having a predetermined outside cross-sectional area defining with said passageway and annular restriction of smaller cross-sectional area between said first chamber and the outlet end of the passageway, a valve member at said second inlet for opening and closing said second inlet, said valve member opening in response to suction created upon movement of air through said restriction, and means limiting opening movement of said valve member for controlling the flow of material to be sprayed through said second inlet, said terminal end of the tube means being located within said passageway substantially in accordance with a relationship wherein A1 is said predetermined area of the passageway and A2 is said predetermined area of the tube means.

3. A spray gun, as defined in claim 1, wherein said valve member is disposed in said second chamber and presents a surface for deflecting material passing from said second inlet into said second chamber.

4. A spray gun, as defined in claim 4, comprising spring means disposed in said second chamber and yieldrably biasing said valve member for closing the second inlet.

5. A spray gun, as defined in claim 1, wherein said means for limiting opening movement of said valve member comprises an adjustable screw member presenting an abutment for engagement with the valve member.

References Cited UNITED STATES PATENTS 1,234,378 7/1917 Parkin 239-424 1,512,132 10/1924 Pfahl 239-4163 1,704,498 3/1929 Deming 239-4162 2,925,148 2/1960 Mosher 239417.5

3,301,486 1/1967 Brock 239371 FOREIGN PATENTS 1,198,019 6/1959 France.

EVERETT W. KIRBY, Primary Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 ,394 ,888 July 30, 1968 Lester F. Dasse et al.

It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shmm below:

Column 4, line 9, "30% to 40" should read 30% to 40% Column 6, line 18, claim reference numeral "4" should read 3 Signed and sealed this 6th day of January 1970.

(SEAL) Attest:

Edward M. Fletcher, J r.

Attesting Officer Commissioner of Patents WILLIAM E. SCHUYLER, JR.

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