US2772683A

US2772683A - Mask-cleaning machine

Info

Publication number: US2772683A
Application number: US299540A
Authority: US
Inventors: Szczepanski Harry
Original assignee: Individual
Current assignee: Individual
Priority date: 1952-07-18
Filing date: 1952-07-18
Publication date: 1956-12-04
Anticipated expiration: 1973-12-04

Description

Dec. 4, 1956 H. szczEPANsK 2,772,683

MASK-CLEANING MACHINE Filed July 18, 1952 3 Sheets-Sheal io Mm Ma x " /Z. mm

Dec. 4, 1956 Filed July 18, 1952 H. SZCZEPANSKI 2,772,683

MASK-CLEANING MACHINE SSheets-Sheet 2 /nven for Harry Szczepansk/ Affome Dec. 4, 1956 H. SZCZEPANSKI 2,772,683

MASK-CLEANING MACHINE Filed July 18, 1.952 3 Sheets-Sheet 5 f PRESSURE PRESSURE 5/ :l5 0 REGULATOR GAUGE PRESSURE 49 REGULATOR fi TIMER G FOOT 65 VALVE SPRAYING TANK 3-WAY CHECK VALVE VALVE FLUI D TANK 62 lnvemor Harry $zczepanski -ya A,

' Affornex United States Patent MASK-CLEANING MACHINE Harry Szczepauski, Grand Rapids, Mich.

Application July 18, 1952, Serial No. 299,540

4 Claims. (Cl. 134-44) The present invention provides a mask-cleaning machine for use in conjunction with spray painting equipment. Quantity production painting of intricate designs is done with the aid of a shield having cut-out areas corresponding to the areas to be painted on the products. The mask and product are placed in proper relationship, and a spray nozzle is directed at the opposite side of the mask from the object to be painted. With this arrangement, the only portions of the object receiving paint will be those opposite the open areas in the mask. Many instances occur in which a portion of the mask is completely surrounded by a cutaway part, and becomes an island requiring structural support from the adjacent areas. To avoid interfering with the passage of paint, these areas are conventionally supported by bridging. This structure is usually in the form of wire displaced a substantial amount from the plane of the mask. With the bridging displaced in this fashion, it is possible to work around the obstruction presented by it, and thus assure that an adequate and uniform layer of paint is applied to the product. During the use of these masks, a layer of paint progressively builds up on the bridging and around the edges of the cutaway areas to a point where the shape of the clear area is distorted. As the paint accumulates on the bridging, it becomes increasingly difiicult to assure that the-re are no areas on the painted surfaces that have been blocked off by the presence of the enlarged bridging. The greater the thickness of the bridging, the more attention must be given to displacement of the guns to spray on either side of it, or the more dispersion of spray from adjacent nozzles is required.

Due to the problems resulting from the build-up of paint on the mask structure, it is conventional practice to periodically clean them through exposing them to solvents of various descriptions. The particular solvent used will of course be selected for the type of paint being handled by the spraying operation, but solvents apparently have a rather uniform characteristic of being highly inflammable. Several types of machines are known to the prior art involving the exposure of masks to a spray of solvent, the spray being motivated by a system of pumps driven by electric motors. The presence of electrical wiring, motors, switches, and similar equipment in a machine utilizing highly inflammable solutions presents a considerable fire hazard; The attention that must be given to such mechanical and electrical installations to minimize the fire hazard considerably increases the cost of the unit in the first instance, and also the maintenance of it in a safe condition. It must also be notedthat the possibility of failure of an electrical system is never completely eliminated, even though great precautions are taken. As long as it is necessary to operate highly inflammable solvents in the presence of electrical systems, a substantial fire hazard is present. This situation is generally recognized by insurance underwriters.

The present inventionprovides a machine for cleaning masks in which there are no electrical systems involved,

2,772,683 Patented Dec. 4, 1956 and in which there is a minimum of mechanical equipment of any description. The force utilized by the present invention to motivate the sprays and the other Working components is derived from compressed air. The majority of factories and other locations where high production spray painting is performed are already equipped with compressed air, for it must be utilized in check valve in the drain, and an arrangement for supplying air pressure over the surface of the liquid in the container so as to drive the solvent through the conduit and to the sprays. After the period of application of air pressure is over, the pressure is released and the solution drains down back into the container and is ready for another cycle of operation.

This invention provides a reciprocating mask-supporting rack, and an arrangement for automatically controlling a spraying cycle which begins after the rack has reached its fully inserted position. An arrangement is also provided by the present invention for purging the machine of a particular solvent that may have previously been in use. With the purging system, it is possible to use the solventmoving system in such a fashion that the entire solution content of the machine is discharged through a hose which may be placed in communication with some other conta-iner.

The several features of the present invention will be discussed in detail through an analysis of. the embodiments illustrated in the accompanying drawings. In these drawlngs:

Figure 1 presents a front elevation of one modification of a machine embodying the present invention, with a portion of the housing broken away to show the interior construction.

Figure 2 presents a section on the plane 2-2 of Figure 1, and constitutes a sectional elevation taken from the side.

Figure 3 shows a section taken on the plane 3-3 of Figure 1.

Figure 4 presents a schematic diagram of the relationship of the components of the embodiment of the present invention illustrated in Figures 1-3.

Figure 5 presents a section taken on the plane 55 of Figure 2, on an enlarged scale.

Figure 6- shows an'enlarged illustration of the self-moving nozzles utilized in the machine illustrated in the previous views.

Referring to Figure 1, a series of masks 10 is shown supported on a vertically-reciprocating rack 11 mounted upon aset of rods 12 slideably mounted in bearings 13. The bearings 13 are mounted on a plate 14 secured to the housing 15 of the machine. The piston rod 16 is vertically reciprocated by an air cylinder 17, and is connected to the rack rods 12 by the end fitting 18.

A spray chamber is defined within the machine by the inner wall 19, the bottom 20, and on the other sides by the walls of the housing 15 and the cover 21. The construction of the cover 21 and the housing 15 at the point where these components come together is indicated at Figure 5. It is preferable that

horizontal flanges

22 and 23 upon the cover and housing respectively also be provided with

vertical flanges

24 and 25, with the flange 24 on the cover extending to a point below the. lower ext-remity of the corresponding flange upon the housing. This arrangementinhibits any tendency of spray from the central area within the chamber to work its way out between the cover and housing. It is also very preferable to provide an insert 26 of non-ferrous material (preferably brass) to inhibit any tendency to generate a spark as tools or other equipment are brought in contact with the cover or housing during periods in which the cover is open.

A central opening 27 in the cover 21 provides for the insertion of the masks within the spray chamber as the rack 11 moves downwardly under the action of the air cylinder 17. In the modification shown in Figures 1 and 2, a seal 28 is provided on the rack 11 to close off any possible openings between the rack 11 and the top 21 after the rack is in the fully down position. After the rack has reached this position, sets of

spray heads

29 and 30 on opposite sides of the chamber begin to pro ject solvent at the masks 10 under the action of equipment to be discussed hereinafter. After the spraying cycle has been completed, the solvent accumulates at the bottom of the chamber and returns to the tank or container 31 via the conduit 32. A check valve 33 prevents any passage of liquid or air in a direction opposite to the arrow 34. If desired, the spray chamber may be ventilated by the application of suction to the conduit 35 communicating with the housing at the manifold 36 through the louvers 37.

The particular spray head used in the machine illustrated in Figures 1 and 2 is illustrated in detail in Figure 6. The

spray head systems

29 and 30 are mounted upon the conduit-s 38 and 39, respectively, and each contain a length of flexible conduit as indicated at 41) in Figure 6. A nozzle 41 of conventional design is positioned at the outer extremity of the flexible conduit 40, and the reaction at this nozzle from the propulsion of the spray tends to make the head position somewhat unstable. As the axis of spray deviates from a straight line, a tendency is established for the spray head to move laterally and bend the conduit 40. This lateral movement usually results in reversing the relative position of the spray axis and the inner end of the flexible conduit 40, and produces a random oscillating movement. The flexible conduit 40 can be satisfactorily constructed from a section of suitable rubber tubing 43 reinforced by a helical wire spring 44.

Referring to Figure 4, a schematic diagram is presented illustrating the relationship between the components of the machine. An air inlet located at any convenient part of the machine supplies compressed air to the conduit 45. A conduit 46 supplies air to the lower portion of the air cylinder 17 via the pressure regulator 47. Another conduit 48 supplies air through the pressure regulator 49 to the timing unit 50, a pressure gauge 51 being associated with the pressure regulator to indicate the pressure established thereby. A foot valve 52 communicates with the main air line via the conduit 53, and also communicates with the timer 50 through the conduit 54. The timer 50 supplies compressed air to the conduit 55 for a predetermined duration of time established by the setting of the adjusting screw 56 in response to actuation of the foot valve 52, the duration of the foot valve actuation being of no importance. The setting of the pressure regulator 49 is such that higher pressure is supplied to the conduit 55 and to the upper end of the air cylinder 17 through the conduit 57 than is supplied to the lower end of the air cylinder 17 by the conduit 46. Consequently, actuation of the foot valve 52 immediately creates a higher pressure above the piston than below, and causes the piston rod 16 to move downwardly. The rack-actuated valve 58 blocks the conduit 59 until the rack 11 is in .its fully down position and inserted in the spray chamber, at which time the air pressure of the conduit 55 is supplied to the tank 31 through the conduit 59. Referring back to Figure l for a moment, the valve 58 (not shown in Figure 1) is operated by the actuator 61 associated with the air 4 cylinder 17 As the end fitting 18 reaches the fully down position, the actuator 61 is contacted and is urged in a downward direction. Such movement opens the valve 58. The valve 58 may be of any conventional form.

Application of pressure to the tank 31 causes the solvent contained therein to move through the conduit 62 through the valve 63 normally through the conduit 64 to the spray heads within the chamber indicated at 65. The valve 63 may also be set for removing from the machine all of the solvent contained within the fluid tank 31 by a proper setting of the valve. Such an arrangement directs the fluid from the conduit 62 through the discharge conduit 66 normally positioned with its discharge end 67 supported upon a suitable bracket 68 within the chamber 65. The purpose of this arrangement is to prevent accidental misplacement of the valve 63 from resulting in discharging the contents of the tank 31 out on the floor surrounding the machine. When it is desired to discharge the contents of the tank 31, the flexible conduit 66 is withdrawn from its position in the tank and directed into another container.

On completion of the duration of the surge of compressed air established by the timer 50, the pressure to the fluid tank ceases. Due to the conventional construction within the timer 50, a valve 71 establishes a line of exhaust from the fluid tank back through the check valve 70 and the conduit 69 through the timer 50, and from there either into the atmosphere through a vent 42 or through a suitable conduit into the interior of the spraying chamber. The latter arrangement is preferable if a ventilation system similar to that shown in Figure 2 is utilized. The presence of the check valve 70 prevents application of pressure to the tank before the operation of the rack-actuated valve 58.

The particular details of the present invention illustrated in the accompanying drawings and discussed herein are for illustrative purposes only and are not to be considered as a limitation upon the scope of the appended claims. In these claims, it is my intention to claim the entire invention disclosed herein except as I am limited by the prior art.

I claim:

1. A mask-cleaning machine, comprising: means forming a spray chamber; rack means for supporting masks in said spray chamber; spray means disposed within said chamber to direct spray at masks supported by said rack means; a solvent container disposed below said chamber; drain means connecting the bottom of said chamber with said container, said drain means including a one-way valve preventing flow from said container; conduit means connecting said container with said spray means to supply solvent thereto; air-pressure supply means including control means and adapted to apply pressure to said container to induce flow of solvent to said spray means, said airpressure supply means including air release valve means, timing means actuating said air release valve means to exhaust the air pressure from said container on completion of a solvent-spraying action; and purging means including selector valve means in the conduit means connecting said container with said spray means and adapted to divert flow therefrom, said purging means including an extensible discharge conduit connected to said selector valve means, the end of said discharge conduit being normally disposed within said spray chamber for discharge thereinto and extendable therefrom for discharge externally of said chamber.

2. A mask-cleaning machine, comprising: means forming a spray chamber; rack means for supporting masks in said spray chamber; spray means disposed within said chamber to direct spray at'masks supported by said rack means; a solvent container disposed below said chamber; drain means connecting the bottom of said chamber with said container, said drain means including a one-way valve preventing flow from said container; conduit means connecting said container with said spray means to supply solvent thereto; air-pressure supply means including control means and adapted to apply pressure to said container to induce flow of solvent to said spray means, said airpressure supply means including air release valve means, timing means actuating said air release valve means to exhaust the air pressure from said container on completion of a solvent-spraying action; and purging means including selector valve means communicating with said container, said purging means including an extensible discharge conduit connected to said selector valve means the end of said discharge conduit being normally disposed within said spray chamber for discharge thereinto and extendable therefrom for discharge externally of said chamber.

3. A mask-cleaning machine, comprising: means forming a spray chamber having an opening in the top thereof; rack means for supporting masks in said spray chamber, said rack means having a portion adapted to close said opening; rack-withdrawing means adapted to withdraw said rack means together with supported masks from said spray chamber through said opening, said rack-withdrawing mean including a member secured to said rack and slideably mounted with respect to said spray chamber, and also including air cylinder means provided with piston means and adapted to reciprocate said member; spray means disposed within said chamber to direct spray at masks supported by said rack means; a solvent container disposed below said chamber; drain means connecting the bottom of said chamber with said container, said drain means including a one-way valve preventing flow from said container; conduit means connecting said container with said spray means to supply solvent thereto; first air-pressure supply means, said first air-pressure supply means including control means and adapted to apply pressure to said air cylinder means to position said rack in said chamber and to said container to induce flow of solvent to said spray means, said air-pressure supply means including air release means adapted to exhaust the air pressure from said container and from said air cylinder on the side of said piston appropriate to induce inward movement of said rack means on completion of a solvent-spraying action; rack-actuated valve means preventing flow of air to said container until said rack portion has substantially closed said opening; one-way by-pass air exhaust means around said rack-actuated valve means; and biasing means urging said piston in a direction to withdraw said rack, said biasing means including second I 4. A mask-cleaning machine, comprising: means forming a spray chamber having an opening; rack means for supporting masks in said spray chamber, said rack means having a portion adapted to close said opening; rackwithdrawing means adapted to withdraw said rack means together with supported masks from said spray chamber through said opening, said rack-withdrawing means including a member secured to said rack and slideably mounted with respect to said spray chamber, and also in cluding air cylinder means provided with piston means and adapted to reciprocate said member; spray means disposed within said chamber to direct spray at masks supported by said rack means; a solvent container disposed below said chamber; drain means connecting the bottom of said chamber with said container, said drain means including a one-way valve preventing flow from said container; conduit means connecting said container with said spray means to supply solvent thereto; airpressure supply means including control means and adapted to apply pressure to said air cylinder means to position said rack in said chamber and to said container to induce fiow of solvent to said spray means, said air pressure supply means including air release means adapted to exhaust the air pressure from said container and from said air cylinder on the side of said piston means appropriate to induce inward movement of said rack means on completion of a solvent-spraying action; rack-actuated valve means preventing flow of air to said container until said rack portion has substantially closed said opening; one-way by-pass air exhaust means around said rackactuated valve means; and biasing means urging said piston in a direction to Withdraw said rack, said biasing means being adapted to apply forces less in magnitude than those applied by air pressure to induce inward movement of said rack.

References Cited in the file of this patent UNITED STATES PATENTS 1,122,887 Engel Dec. 29, 1914 1,667,119 Kehoe Apr. 24, 1928 2,080,745 Roche May 18, 1937 2,239,110 Mahoney Apr. 22, 1941 2,243,446 Terlesky May 27, 1941 2,322,729 Holman June 22, 1943 2,471,506 Wiswall May 31, 1949 2,554,389 Stevens May 22, 1951 2,570,021 Beach Oct. 2, 1951 2,618,281 Ornas Nov. 18, 1952 2,619,974 Daley Dec. 2, 1952 FOREIGN PATENTS 672,273 France Sept. 16, 1929