US1858475A - Sand blasting machine - Google Patents

Description

May 17, 1932. F. H. WOLEVER SAND BLASTING MACHINE Original .Filed Feb. 4, 1924 m m m m Patented May 17, 1932 FRANKLIN H, WOIIEVER, OF CHICAGO, ILLINOIS SAND BLASTING MACHINE Original application filed February 4, 1924, Serial No. 690,387. Divided and this application filedOctober This invention relates to improvements in sand blasting apparatus of that type that employs air at a high pressure as a medium of propelling sand or other abrasives at high velocity through a. nozzle against metallic or any other substance to be treated.

Among the common faults with sand blast apparatus now in commercial use may be summed up the following; lack of positive sand flow, which causes intermittent volume variations of sand flow and varying velocities; inconveniently located manual controls remote from operative points; lack of proper provisions for ready access to vital parts of the operative mechanism to remove obstructions; lack of' means for establishing sand flow after the sand blast has been shut off without experimentation with the sand and air valves, and inconvenient means for filling the sand tank after it has been emptied.

The various features of novelty whereby my invention is characterized will hereinafter be pointed out with particularity in the claim; but, for a fullflunderstanding of my invention and of its objects and advantages, reference may be had to the following detailed description taken inconnection with 'A the accompanying drawings, wherein:

Figure 1 is a vertical central section through an apparatus arranged in accordance with my invention, only the end portions of the tank being shown; Fig. 2 is a section on line 22 of Fig. 1; and Fig. 3 is a section, on an enlarged scale, on line 33 of Fig. 1.

Referring to the drawings H is a sand tank to which clean sand is delivered through a pipe 12; the sand first entering a. receiving chamber H at the top of the tank. The sand is fed in the operation of the machine through the hopper bottom of the tank and through asand measuring'apparatus J and thence through the nozzle hose K to the manually operated jet nozzle K by which the blasting sand is directed at suitable velocity and volume onto the work.

Said pipe 12 leads tangentially into the side of the receiver, as shown in Figs. 1 and 2. The speed of the sand thereby is reduced and the sand is agitated as it enters the said receiver by impact against a series of radial Serial No. 310,412.

trolled by a cone shaped valve 56, which controls the flow of sand from the receiver to the tank. Said valve is vertically movable and seats upwardly against a ring 57, which, as herein shown, iswithin' the to of the tank H in axial alignment with the receiver and constitutes a continuation thereof. The ring is fixed in any suitable manner to the top .wall it of said tank, and its lower seating face is formed by an annular tapered body of resilient substance 58, such as rubber, to produce an. air tight joint between the conevshaped valve and said'seat, fora purpose presently to appear. The said valve has a vertical stem which extends upwardly through a tubular guide'60 carried by a spider within the receiver,and through a neck 61 having'at its upper end a stem guide 62. n expansion spring .63'is interposed between an upper face on said neck and a shoulder 64 on the stem above the neck (formed by a threaded nut) and acts normally to hold the cone-like valve againstits tapered seat.

A discharge outlet 66 at the upper end of said neck'permits dust and light particles from the'agitated sand in said receiver to be withdrawn if a suitable suction device is connected to the outlet. Thus the sand is subjected to a final cleaning action before it is discharged into thefsand tank. When the sand tank is to be filled, the jet pump is set in operation to raise the sand from the sand pit into the receiver H and the agitation of the sand as-it enters the receiver, due .to its impact against the wings 55, serves to allow the speed of the sand and to cause the sand to drop by gravity and the dust and lighter particles to be separated from the sand by the action of the draft of air through the pipe 66, due to the low pressure in the chamber C, so that the sand is prepared in readiness for entrance into the tank in a cleanly condition. 1

The seating strength of the spring 63 can be so regulated, as by the nut 64, that a given weight of sand overcomes it and opens the cone-like valve to allow the sand to flow by gravity into the tank below. The said spring 63, regulated as it is, cooperates with gravity to control the sand flow until the tank has been filled, and after the operation of the sand jet pump has been stopped, the. .said spring acts to hold the valve hard against its seat to provide a joint against the escape of air through the filling valve thus described during the sand blast operation.

An air vent is established from the tank while the tank is-beingfilled through a vent pipe 68', the top of which opens near the top wall ofth'e tank. Said vent pipe extends downwardly through the hopper bottom of the tank and is provided exteriorto the tank with a branch 69 which discharges into the air. As herein shown, and for a purpose hereinafter to be described, the said branch opens into a chamber 7 O, which can be fastened to the tank structure. Said chamber is provided at its bottom with an outlet or vent opening 71 which is adapted to be open when the said tank is being filled, so as to equalize the tank pressure with the operating pressure. To this end, the vent or equalizing pipe extends beyond the outlet branch 69 to form an extension for a purpose presently to appear.

After the sand tank is filled, the sand is discharged in measured quantities therefrom through the nozzle K under the control of a suitable volume and pressure control means.

The embodiment of said control means illustrated is made as follows:

75 designates a rotative measuring bowl which is axially below the discharge nozzle 76 of the sand tank at the conical lower end of the tank. As shown, the nozzle is formed as an integral part of the casing 77 of a meas uring device and the smaller discharge of the said tank is flanged for attachment to the upper flattened end of said casing, with the tank discharge h in line with said nozzle. The

measuring bowl is fixedto and rotates with a vertical stub shaft 78 which 1s rotatively mounted in a bearing 79 that is carried by and is partly enclosed in a shell 80 of suitable form to protect said hearing from dust and sand. The bearing is further protected at the point where the hub of the bowl and the bearing members meet by a skirt 80 which is arranged in overlapping relation to the upper conical end of said shell 80. Fixed to the lower end of said shaft 78 is a beveled gear wheel 81 thatmeshes with a beveled pinion 82. Said pinion is fast to the inner end of a shaft 83 that is mounted to rotate in a bearing 84 which is carried by the casing 77. The lower, tapered end 85 of the measuring the nozzle K.

chamber 104 of said casing.

device casing has the form of a neck 86 that can be made integral with a fitting 87, herein shown to be the casing of a sand pump, through the medium of which sand is delivered from the measuring device casing to the sand discharge tube and nozzle, as will hereinafter be described.

The shaft 83 is fixed to a worm gear 88 which meshes with a worm 89 that is fixed to and rotates withthe shaft of an air turbine 90. Said worm gears are enclosed in a suitably shaped sand proof casing to protect them from sand and dust. 91 designates the casing of the air turbine 90, one side of which casing is open to one branch 106 of a pressure pipe 92. Saidpipe 92 has a flanged, axial connection atits lower and with the tapered receiving end 93 of the said pump casing 87., there being a pressure chamber 9 1 formed in said tapered formation 93 between the adjacent end ofthe pipe 92 and a transverse wall or portion 95 in said sand pump casing87.

Connected to theend of the pipe 92; remote from the sand pump isa pipe 97 for "deliveringair under pressureto the pipe 92, for

the. double purpose of furnishing air to operate the turbine and for operating the sand pump by which the sand is forced through Said pipe 97 has a cut-ofi and controlling valve 98. The pipe 97 commun icates with the pipe 92 through one lateral branch of a fitting 99, another branch of the fitting being connected directly to the conduit 92. Said fitting is valve controlled to shut ofl air pressure from the pipe 97 when the'sand tank is being filled and when the blasting operation is discontinued. A valve 100 for this purpose is shown as being closed.

Said valve 100 is a tapered faced closure to engage alike-shaped seat in a diaphragm of the fitting 99. The stem 101 of said valve extends through a stuffing box at the top of the fitting, and is connected by a coupling 102 with the lower end of a stem 103. The stem 103 extends upwardly through a chamher 104 made of upper and lower casing members and is connected to a diaphragm 105 which extends across said chamber, with the margin thereof confined between the margins of the members of the two part casing ina known manner. Said stem 103 extends through a stuffing box in the lower casing member to maintain air tight in the lower The stem is surrounded in its part between said dia phragm andthe top member of the casing by a spiral expansion spring 107 the normal tendency of which is to closesaid valve 100. The upper end of the stem 103, above the casing 10 1,'carries a disc valve 103 to close the vent opening 71 in the equalizing chamber 70 before referred to.

Located within the conduit 92, abreast the air turbine, is a partition 105 which is free at its upper and'lower ends from the conduit wall and, in efiect, provides two branch conduits 106, 107, the former of which directs air to the vanes of the turbine, and the latter of which shunts air from the turbine blades and directs it to the sand pump beneath the measuring mechanism. The said branches 106, 107 are adaptedto be separately controlled to vary the volume of air passing therethrough by any suitable control or throttle means such, for instance, as by means of studs 108, 109 that are threaded through the opposite walls of the conduit and are adapted at their inner ends to approach and recede from the partition 105.

The sand pump embraces, in addition to the parts already described, a tube 110 which lies axially within the casing 87 and is fixed at its rear end in a central opening in the partition 95. Said tube, therefore, affords free passage for air centrally through the pump chamber. The sand falls around the tube 110 in front of the partition 95. Said partition has in its lower part a plurality of openings 112. Air, under pressure, therefore, passes through said tube and through said openings 112 and acts with an aspirator effect to forcibly discharge the sand from the pump casing through the nozzle. The nozzle has a restricted throat near its outer end afforded by a liner 114 made of a substance to resist wear. The said liner is flare-d at both ends and restricted between its ends so as to thereby impose a resistance to sand discharge and to increase the velocity of the sand projected from the nozzle.

Located at, and preferably carried by the nozzle piece is a cut-off and control valve, designated as a whole by 115. As shown, its casing is provided with a collar 116 which is clamped about the hose K at the point where it laps over the nozzle piece K to thereby fasten the valve in place and to clamp the hose on the nozzle piece. The casing of said control valve is formed with three tubular branches 117, 118, and 119. The branch 117 opens to the atmosphere. The

branch 118 is connected by a flexible hose 120 and a pipe 121 with the lower chamber 104 of the diaphragm casing 104. The branch 119 is connected by a flexible hose 122 and a pipe 123 with the main pressure pipe 97 just inside its valve 98. 124 is a plug that is rotatively seated in said casing and is provided with an actuating handle 125. Said plug is provided with two curved internal ports 126, 127, the ends of which are spaced angular distances apart equal to the angular spacings of the ports in the branches of the casing, the spacings being 90 as herein shown.

In the adjustment of the parts as shown, the lower chamber 104 of the diaphragm chamber 104 is open, through the port 127 in the plug, to atmosphere, so that the spring thereby to the air turbine and the sand pump.

Such air line pressure is also operative to closethe valve disc 103 against the sand tank vent opening 71. These are the operative positions of the parts for sand blasting. 128

designates a branch I which leads from the extension of the equalizing pipe 68 and communicates with the casing 77 enclosing the sand volume control mechanism, where pres sure in-said casing and the tank can be equalized .during the sand blasting operation of the machine. J

It is desirable that means he provided for limiting the effect of the sand head in the tank H, so as to thereby reduce the feed velocity of the sand from said tank to the measuring device. This result can be efiected by arranging a cone-like shelf or diaphragm 180 within the sand tankabove its discharge nozzle 76, and supporting it centrally in said tank by brackets 131 from the wall of the tank.

This central "support or shelf will modify the flow line of the sand in the manner indicated in the drawings, and reduce the head pressure of the sand at the outlet nozzle to an extent represented by the area of said shelf.

In order that free access may be had to the outlet of the tank to remove clogging obstructions, a hood 132 is arranged below said shelf transversely across the conical lower end of the tank. The hood can be supported on opposite walls of the tapered portion of the tank. At oneend of said hood the tank wall is provided with a hand hole 133, covered by a suitable closure. Through the hand hole any suitable implement can be inserted into the restricted outflow of the tank to clear the outflow of any obstruction that may lodge there. The presence of said hood, to the extent that its side margins intercept the normal flow line from the margins of said shelf 130 further reduces the sand head pressure at the tank outlet. j

I To start sand blasting, the compressed air valve 98 is turned on and the operator takes the nozzle K in his hand and turns the control valve plug to a suitable stop (not shown) which registers the port 126 with the proper casing ports to connect the pressure pipe 97 to the chamber 104 beneath the diaphragm.

The increased area. of surface of the diaphragm over the net surface of the valve causes the valve 100 to lift and to thereby compress spring .107and to also cause the disc valve 103 to seat against and close the vent port 71 through which the tank pressure was theretofore equalized with atmosphere.

The sand tank is now sealed ofi from the atmosphere and compressed air now flows 5 through valve 98 through the opening controlled by the valve 100, and thence through the branch passages 106 and 107 of the conduit 92. A portion of the air. is passed through the passage 106'over the vanes of 10 the turbine to drive the same and another portion is diverted through the branch pas- "sage 107 to the chamber 94 at the rear of the nozzle sand'pump, and thence through nozzle hose K and the nozzle K. The air pressure I5 built up in the chamber 94 of the sand pump carries the sand deliveredto the pump casing through the hose and discharges it fromnozzle K onto the work.

The small area of the nozzle K as compared tothe area of intake air passages 110, 112 builds up pressure in chambers 94 and 77, which is soon equalized in the tank by flow of air from said chamber 77 through,

the equalizing branch 128 and pipe 68 to the tank. This pressure also serves to seat the sand feed control cone: valve 56 more tightly than by the action of the spring 63 alone. As soon as pressure is equalized in the tank, the casing 77 and the said pump, sand will begin to flow from the tank onto cup 75, which is being driven by the turbine '90 at a rate of speed due to the control of the branch 106 which delivers air to said turbine. Rotation of the bowl acts to centrifugally throw the sand delivered thereto outwardly and cause it to fiow to the restricted outlet or passage of the casing 77, from whence itis forced to the discharge or blasting nozzle K. Obviously the more rapidly the bowl is rotated the greater will be the volume of sand delivered down through the nozzle 76 of the sand tank. The control of the speed of this bowl, through controlling its driving turbine by the ac- 45 tion of the valve 109 or equivalent throttling means, has the effect to vary the volume of sand delivered to the sand pump below in a given time. Likewise, the operation. of the valve 108 or an equivalent control for the high pressure branch 107 serves to control the velocity at which air is delivered to the chamber 94 of the sand pump. With 97 to the conduit 92 and to the pressure chamber 104- of the diaphragm casing and to When sand from the tank H has been exhausted, the valve 115 at the nozzle K is turned by its handle 125, so as to close communication from the feed or pressure pipe establish communication from said diaphragm chamber 104 to the atmosphere. The spring 107 then becomes active on the diaphragm to close the valve 100 and to open the equalizing port 71 so as to equalize the pressure in the tank with the atmosphere. The tank H is then charged through the pipe 12, after which the hand valve 115 is adjusted to open the valve 100 to connect the feed pressure pipe to the conduit 92, whereupon the machine is again in position for sand blasting operation. 7

The present application is a division of my prior application Serial Number 690,387 85 filed February 4:, 1924.

A sand blasting apparatus comprising a storage tank for blasting sand provided with a discharge opening, a sand pump to receive sand from said discharge opening, a hose connected with the discharge end of said pump, a jet nozzle connected to the free end of said hose, a pressure air line, a conduit connecting said, air line to the inlet side of said'sand pump, a pressure closed valve in said conduit to cut off air pressure to said sand pump, a diaphragm connected to said latter valve, a casing to enclose it, and a manually controlled valve connected to said air line and to said casing and adapted in one adjustment to transfer pressure from the air line to said casing below said valve diaphragm to open the air line valve against the pressure of said line and in another adjustment close the air line to said diaphragm casing and to open said casing to the atmosphere.

In testimony whereof, I sign thisspecification.

FRANKLIN H. WOLEVER.

these controls it will be obvious that the sand I can be accurately varied to suit different kinds of work. With a constant feed pressure in the pipe.97 it will be obvious that the valves 108 and 109 will permit a considerable range of relative volume and velocity of air delivered to the turbine and to the pump through the branches 106, 107, with a corresponding variation, as stated, with respect to the volume and velocity of the sand discharged from the nozzle K onto 65 the work.

volume and velocity discharge at the nozzle

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