US3793778A

US3793778A - Sand blast apparatus

Info

Publication number: US3793778A
Application number: US00014167A
Authority: US
Inventors: R Price
Original assignee: Individual
Current assignee: Individual
Priority date: 1970-02-25
Filing date: 1970-02-25
Publication date: 1974-02-26
Anticipated expiration: 1991-02-26

Abstract

A method and the apparatus for selectively mixing sand or other solid polishing materials (such as glass beads) with a stream of pressurized fluids such as air, and then propelling them through an orifice wherein the solid material is basically under gravity feed actuation and the amount of sand that is allowed to mix with the air is controlled by a combination of a mechanical valve and the reaction of the solid material under the force of gravity to air turbulence within the pressurized system.

Description

O I v United States Patent 1191 1111 3,793,778 Price Feb. 26,1974

[54] SAND BLAST APPARATUS 861,138 7/1907 Newell 51/3 [76] nvento Richard Price 2116 w. t psc 3,032,929 5/l962 Glesener 5l/l2 X Ave., Baltimore, Md. 21230 I Primary Examiner-Donald G. Kelly [22 Filed: Feb. 25, 1970 [2i] Appl. No.: 14,167 7 ABSTRACT I A method and the apparatus for selectively mixing [52] US. Cl. 51/12 sand other Solid polishing materials (such as glass [51] Int. Cl. B24c 5/02, B240 7/00 beads) with a Stream of pressurized fluids such as i [58] held of Search 51/8 321 and then propelling them through an orifice wherein i the solid material is basically under gravity feed actua- [56] References C'ted tion and the amount of sand that is allowed to mix UN T STATES PATENTS with the air is controlled by a combination of a me- 968,350 8/1910 Harrison; 51/11 1.1x h ni al al and the reaction of the solid material 885,069 4/1908 Mullikin under the force of gravity to air turbulence within the 2,305,976 12/1942 McKnight..... pressurized system.

346,650 8/1886 Freeman 699,405 5/1902 Newhouse 51/12 3 Claims, 3 Drawing Figures i SAND BLAST APPARATUS BACKGROUND OF INVENTION This equipment is one of a series of similar pieces of equipment designed for selectively applying abrasives or other solid material in a fluid such as air or liquid wherein the abrasive is variously admitted to the fluid air stream by venturi action, gravity action, pressure action, mechanical valve action, and similar actions whereby there is a regulating of the mixture between the air and the solid particles.

Prior Art The Prior Art consists largely of a venturi or pressure or a gravity method of mixing the sand with a stream of air. Examples of this are shown in U.S. Pat. Nos. 2,766,558 by Black; 3,032,929 by Glesener; 1,706,222 by Fatscher; 2,938,305 by Bipes; 2,372,957 by Keefer; and 671,303by Warren. The Warren apparatus seems to be basically a mechanically controlled gravity flow device with a method of pressure equalization. The Keefer device has a curved throat which joins with an enlarged or venturi type chamber area indicating that it appears to operate by a vacuum or pressure differential principle and Bipes appears to have a pressure assist to that general principle and Fatscher again uses the venturi or suction-pressure differential principle while Glesener and Black work on a mixing chamber where air, sand are mixed and further adjusted by suction for the feed of the sand/air mixture. Most of these devices stated above use quite a bit of the working power of the air to move the sand from the position of storage into the position where it is mixed with air in the high velocity chamber prior to expelling it through an orifice. Of course, this is true except for the simple gravity-feed devices. The gravity-feed devices require a delicate balance between the air pressure and the gravity pressures which must be adjusted by the various valves. The gravity pressure then differs as the amount of sand is used. In the subject invention, air turbulence is used to provide a back pressure to support the sand and to resist the action of gravity and as such, this tends to equalize the amount of sand mixed with air at a particular time and does not unnecessarily waste energyof the air in moving the sand. Also, this device has three distinct modes of operation which give an advantage of flexibility of operation; adjustable sand orifice, adjustable air orifice and no adjustable orifices.

SUMMARY OF THE INVENTION This invention consists of a device which, when attached to a supply of air pressure, and the air pressure is adjusted for optimum results, allows a gravity operation of sand or other abrasive against a sand valve regulator and against a turbulence in the air pressure tube and by the combination of the action of the valve, the air pressure, the turbulence created by the flow of air, allow for a propelling 'of the abrasive material with a substantial savings in volume and air pressure necessary to achieve the same amount of propelling. Thus, the device, for example, will allow sand blasting to occur preferably with a simple air compressor such as one-third horsepower 1$ h.p.) operating at 35 to40 lbs. pressure through a 5/32 inch to 7/32 inch orifice.

orifice in order to achieve the same rate of sand abrasive action. (See Empire Abrasive Equipment Corp., 3063 Miller Street, Philadelphia, Pa. 19134, catalogue page 19.)

DESCRIPTION OF THE DRAWINGS FIG. 1 is a partial cross-section, elevational view of the subject invention.

FIG. 2 is an alternative of FIG. 1 in an elevational drawing showing one modification; that is, one of no air control valve and showing it in the operative and alternative inoperative position.

FIG. 3 is an elevational view of a third modification of the subject device showing a simplified version of FIG. 1 wherein there are no valves for either the sand or the air, and on-off operation is achieved by placing the device in the alternative position.

A listing of the parts involved in this device is as follows: 10 is the low-pressure abrasive gun; 12 is the abrasive container; 14 is the sand or other abrasive or polishing material such as glass beads; 16 is the throat or container adapter for attaching the sand cup; 18 is Y the abrasive-valve handle; 20 is the abrasive conduit to Under all of the existing conventional forms of sand blasting equipment, it would be necessary, in order to achieve the same delivery of abrasive sand, to go to as much as 3 h.p. and to lbs. air pressure with 3 to 5 cu. ft. per minute and approximately the same size allow the sand to enter the valve chamber area;'22 is the valve orifice. The air supply valve handle is 24; the air supply valve orifice is 26; the threads or other devices (shown but not claimed) for attaching the inven-' 'tion to the supply of air is 28; air supply is 30. The nozzle is 32; with the nozzle orifice 34. Within the tube, the air transit tube, there are three parts to this air chamber marked as a, b, and c.

In the preferred embodiment of the subject invention, you have a supply of sand 14, or otherabrasive or polishing material contained in airtight chamber 12, which is attached to an adapting conduit 16 and this sand by gravity, is forced down to the conduit area of 20. The T-shaped air chambers a, b, and c are connected so that air pressure from a source is usually about 35 to 40 lbs. pressure per sq. in. at 2 to 3 cu. ft. per minute, is regulated through the valve handle 24 and valve orifice 26 into chamber a. There the air will flow, and assuming sand valve 18 to have its orifice 22 closed, and then proceed straight down a to c and on out through orifice 34. As a matter of interest, this procedure of the air flowing down from a through c takes place in a slightly spiral manner, as a rule. It is believed that this is due to the Coriolis force, having to do with earths gravity; however, by further observation, it is shown that the air also proceeds not only from a to c but a portion of it goes up one side wall of the conduit area B and comes down the other sidewall, making, in effect, an incursive letter e shape. Thus the air sets up a turbulence just below the valve orifice 22 where a portion of this air passing from 30 to 34 must turn around as it goes up the little side aisle b. When valve orifice 22 is open to allow some sand to drift down by gravity, the first thing that must be overcome is a little bit of backpressure due to the fact that the air flowing up one side of tube b and down the other, and turning around right at the entrance of the orifice 22. This action tends to clean out the orifice and blow the sand back against gravity. With 40 lbs. of pressure, this is merely a slight backpressure and not sufficient to prevent the gravity flow of one to 4 or 5 inches of sand pressure. However, with an air pressure of 60 or lbs., and all other conditions being the same, the turbulence just below the valve would be sufficient to suspend the one to inches of sand and not let it come down, even through a fully opened orifice. It is this action and reaction of the air of turning around just below this valve that it is believed is partly responsible for the good performance and ease of cleaning this device because now the device can operate at almost 0 work conditions insofar as the amount of air that must be used to move the sand into the proper propelling path of channel c and on through orifice 34. Of course, at this point it is clearly seen that by restricting orifice 34, the volume of air or air and sand or other particulate matter can be matched to the volume output of your pump and thus in one modification (FIG. 2) all that is needed is a valve 18 for the sand tube to adjust the ratio of sand to air, that is desired. For an inoperative position, merely move the cup to position 36 (FIG. 2) cutting off the supply of sand without changing position of the abrasiveflow rate valve 18. The air going through the orifice 34 being matched to the pump capacity (equal to or less than) and being the only other operation necessary to turn the air supply pump (not shown) on and off at the beginning or ending of a complete work period. A still further simplification is shown in FIG. 3 whereby adjusting the size of the opening in throat 20 in a fixed amount and setting the orifice to match the pump capacity, a fixed sand-to-air ratio mixture can be operated by simple attachment to an air supply and the sand blasting operation is merely activated or stopped by placing the cup in the upper or lower position.

What I claim is:

1. In adevice for propelling particulate abrasive material by means of fluid pressure flow the improvement comprising;

a. a first fluid pressure flow path conduit of substantially uniform cross section with an inlet opening at one end and a substantially smaller outlet opening at the opposite end, and a third opening spaced from said two ends at the side of said conduit, b. a second conduit of shorter length than said first conduit but of same cross sectional of diameter located perpendicular to said first conduit and having one end connected to said third opening in said first conduit, and having the remaining end detachably connected to an enlarged closed chamber, for the storage of particulate matter, whereby said fluid flow is turbulently directed substantially in a cursive e path having the top of the e" located substantially at the junction of the chamber and said second conduit, and whereby said fluid flow path means can be oriented to selectively receive by gravity introduction the particulate matter and expelled at said first conduit exit end. 2. In a device for propelling particulate material of the character designated in claim 1 wherein said second conduit has a valve athwart the fluid path for selectively connecting said flow path with said enlarged chamber. 4

3. In a device for propelling particulate material of the character designated in claim 1 wherein said outlet opening is one-third to'one-twentieth the diameter of said first conduit.

Claims

1. In adevice for propelling particulate abrasive material by means of fluid pressure flow the improvement comprising; a. a first fluid pressure flow path conduit of substantially uniform cross section with an inlet opening at one end and a substantially smaller outlet opening at the opposite end, and a third opening spaced from said two ends at the side of said conduit, b. a second conduit of shorter length than said first conduit but of same cross sectional of diameter located perpendicular to said first conduit and having one end connected to said third opening in said first conduit, and having the remaining end detachably connected to an enlarged closed chamber, for the storage of particulate matter, whereby said fluid flow is turbulently directed substantially in a cursive ''''e'''' path having the top of the ''''e'''' located substantially at the junction of the chamber and said second conduit, and whereby said fluid flow path means can be oriented to selectively receive by gravity introduction the particulate matter and expelled at said first conduit exit end.

2. In a device for propelling particulate material of the character designated in claim 1 wherein said second conduit has a valve athwart the fluid path for selectively connecting said flow path with said enlarged chamber.

3. In a device for propelling particulate material of the character designated in claim 1 wherein said outlet opening is one-third to one-twentieth the diameter of said first conduit.