US2779085A - Scaler - Google Patents

Description

Jlan. 29, 1957 w. l.. scHoENGARTH 2,779,085

SCALER 2 Sheets-SheefI l Filed Dec. 3l, 1954 `Iam. 29, 1957 w. L. SCHOENGARTH 2,779,085

SCALER Filed Dec. 31, 1954 2 Sheets-Sheet 2 Ti s--l @o 92 45e@ Se l 5c,

AT TOEN EYS United States Patent O SCALER Walter L. Schoengarth, Redding, Calif.

Application December 31, 1954, Serial No. 479,051

3 Claims. (Cl. 29-81) This invention relates to a tool for removing scale, slag, rust, carbon, paint and the like from metallic or other surfaces.

Summarized briey, the invention is a hand held power tool in which, through the medium-of a motion translating linkage extending from an electric motor, high speed reciprocation is imparted to a piston within a cylinder or pneumatic chamber, in a manner to impart a corresponding high speed movement to a plurality of plunger picks which, when directed against Ithe surface to be cleaned, rapidly remove scale, rust, other eiects of corrosion, paint, and the like. The picks are individually slidable in provided bores, so that, while all the picks are moved toward and away from the work simultaneously, the lengths of their strokes will be governed by the conformation of the work surface. Thus, if some of .the picks encounter a particularly hard formation on the work while others strike relatively soft areas, the latter picks are permitted to travel further inwardly of the work without adverse eiects, so as to facilitate the cleaning operation and so as, further, to particularly adapt the device for use on uneven surfaces such as those occurring at the location where an electric weld or the like has been used to unite metals.

In accordance with the invention, the reciprocating motion of the picks results from the creation, at the back ends of the same, of alternating air pressure and vacuum conditions resulting from the reciprocation of the piston. Within the pneumatic chamber, between the picks and piston, a novelly formed valve assembly is so designed that an outlet valve opens when the picks are moved outwardly and an inlet valve opens when the picks are to be moved inwardly. The valve assembly is so designed as to hold the picks in their retracted positions, during the initial part of the pressure stroke of the piston, for a minute periodlof time, in a manner that causes a pressure to be built up against the picks with a resultant increase in the rapidity of their outstroke.

One important object is to provide a tool as stated which will be manipulable with a high degree of facility, will be light in weight, durable, and efcient in removing diierent types of residues carried by both even and uneven Work surfaces.

Another object is to provide a tool that will be safe in operation, compact, and capable of manufacture at relatively low cost considering the benefits to be obtained from use thereof.

Other objects Will appear from the following description, the claims appended thereto, and from the annexed drawing, in which like reference characters designate like parts throughout the several views, and wherein:

Figure 1 is a top plan View of a tool formed in accordance with the present invention, in which a portion has been shown in longitudinal section;

Figure 2 is an enlarged longitudinal sectional view 0n line 2--2 of Figure l, the picks being shown in retracted position;

Figure 3 is a view on the same cutting plane as Figure 2 showing the head end of the device applied to a pieceof work, the picks being shown in their extended position or outstroke; i

Figure 4 is a transverse sectional View on line v4--24 of Figure 2;

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Figure 5 is a transverse sectional view on line 5-5 of Figure 3;

Figure 6 is an exploded perspective View of the pick y control valve assembly; and

Figure 7 is an exploded perspective View of a vacuum relief valve.

The tool constituting the present invention includes a pistol grip handle 10 cast integrally with a cylindrical, hollow casing 12 formed intermediate its ends with a transverse partition 14 dividing the same into a motor compartment 16 and a driving linkage compartment 18. At one end, the casing is integral with a reduced axial extension 20 of cylindrical formation, providing a piston compartment or pneumatic chamber 22 communicating with compartment 18.

Fixedly mounted in the motor compartment 16 is a conventional electric motor 24, to which power is supplied through a line cord 26. Mounted in the handle is a trigger type switch 28 (Figure 4), where-by the motor can be turned on or oil by the linger of a hand gripping the handle in a natural manner during use of the tool.

The shaft 30 of the motor extends axially of the casing and is journalled in a bearing 32 provided in the partition 14. Shaft 30 extends into the compartment 18, and is there secured to a beveled drive gear or pin 34 meshing with a bevel gear 36 carried by a stub shaft journalled in a bearing 38 mounted on one side wall of the compartment 18. A pitman 40 is connected to the gear 36 and is connected through the medium of a pin 42 tto a piston 44 having piston rings 46 in wiping engagement with the wall of the piston chamber 22. Thus, on operation of the motor the piston 44 is given high speed reciprocating movement between the respective positions shown in Figures 2 and 3.

On reciprocation of the piston, alternating pressure and vacuum conditions occur within chamber 22 to the left of the piston in Figure 2, the piston creating high pressure within the chamber 22 when shifted through its out stroke to the left in Figure 2 from the position thereof shown in this figure, and creating a vacuum when retracted toV its Figure 2 position from its Figure 3 position.

Meansis provided to admit air into chamber 22 should the created Vacuum be excessive. This means comprises a vacuum relief valve generally designated 48, the parts of which are shown in Figure 7. A restricted bore 50 communicates at one end with the chamber 22, and at its other end opens int-o a counterbore 52 on the bottom of which is seated a' concavo-convex spring washer 54 of the spider type. Connected by a rivet to the center of washer 54 is a valve disc 56 normally seating against the inner end of a nut 58. A second nut 60 cooperates with nut 58 in holding therebetween a dust screen 62, the nuts lbeing threaded into the complementarily tapped outer end portion of the counterbore, said counterbore being formed in a boss 64 integrally formed upon the outer surface of the extension 20 of the casing.

Normally, the spring washer 54 holds pin 56 firmly seated against nut 58, and this will be true even when the piston moves through its vacuum stroke and creates a Vacuum condition within the pneumatic chamber '22. Should, however, the vacuum created be such -as to Similarly, occasion may arise for permitting the escape of air from the. chamber 22, should the piston, when v moving through its pressure stroke to its Figure' 3 position, create a'pressure"condition beyond av predetermined;-

value within the chamber. To this end, there is provided a pressure reliefvalve shown in seated andv unseated positions in Figures 2 and 3 respectively. A restricted bore 68 communicates at one end with'the chamber, and at its other end opens into a counterbore '70. A ball element 72, is normally biased by spring 74 to a seated position closing the bore 68, and holding the spring under proper tension are nuts 76 between which is interposed a dust screen 78, said nuts being threaded into the outer end portion of the counterbore. The counterbore is formed in an obliquely extended boss 66 integrally formed upon the outer surface of the extension Zii.

At its outer end, extension is counterbored as at 80, thus forming a circumferential internal shoulder at the base ofthe counterbore Si).v Seated against said shoulder is a plunger pick control valve assembly generally designated 82. In Figure 2,A the partsr of said assembly are shown in the position assumed thereby when the piston is at the end of its vacuum stroke. In Figure 3 the parts are shown in their position when the piston is at the end of its pressure stroke. The parts of the valve assembly are shown per se in the exploded perspective view of Figure 6.

Assembly S2 includes at its inner end, that is, the end thereof faced toward the chamber 22, a concave-convex spring washer 84 of the spider type, the ends of which bear against the marginal portion of a valve disc 86. Disc 86 is normally forced by the pressure of the spring to a seated position against a larger valve disc 88. The disc 86 can be appropriately termed a suction valve disc, for the reason that when unseated, it is unseated due to the creation of a vacuum condition in the chamber 22, of a Value sufiicient to overcome the restraint of spring 84 and thereby draw the disc 86 to the right to its Figure 2 position. This causes the vacuum to be extended to the left in Figure 2 beyond disc 86 into plunger pick bores to be described hereinafter for retracting the plunger picks. Disc SS, on the other hand, can be appropriately termed as a pressure valve disc. Disc 88 is normally seated against the mentioned internal shoulder when there is a vacuum condition within chamber 22. However, it is unseated and moves to the position shown in Figure 3 when a pressure condition is created in chamber 22, so as to cause said pressure to be transmitted past the disc S8 to the plunger pick bores.

The value -disc 88 is formed with a peripheral series of notches 96, the marginal area of the disc 88 in which the notches are formed normally seating, in the retracted piston position, against the internal shoulder of extension 20. The notches are thus closed, and air under pressure cannot be ydirected therethrough under these circumstances.

Disc 88 4is also formed with an annular series of slot like portsA 92 formed in the center portion of the disc 88, in communication with a shallow circular recess 91 ofA the disc.

The ports 92 are closed by the suction valve disc during the pressure stroke of the piston, the suction valve disc being urged into and iilling the shallow recess 91 under pressure from the spring washer 84 under these operating conditions as shown in Figurev 3.

A second spring washer of the spider type designated at94.bears against. the disc 88, tendingto urge the same.

into engagement with. the4 internal shoulder of the casingl extension 2i). At its periphery, the washer 94, is engaged against the marginal part of a plunger pick head plate 96 of a diameter corresponding to that of the counterbore Stb, and formed with a plurality of openings. 98 each of which has a small notch 100 in communication therewith. A center opening 98 is provided, together with an annular series4 of said openingsas shown, to particular. ac lvantage'V in. E igure. 6,.

A plunger;v pick housing, 102., of cylindrical, formation is .externally threaded` atits. inner end,l to engage. in a complementarily threaded outer end portion of the counterbore 80. Exteriorly of the counterhore, the plunger pick housing is integrally formed with a collar 104 having diametrically opposite notches adapted to receive a Spanner wrench or similar tool to.l facilitate the connection of the housing 102 to the casing extension 20. A jam nut 106 is threaded upon the housing 102, against the outer end of extension 20 to insure the firm retention of the housing 102 in its assigned position relative to the casing extension.

Formed in the housing 102 is a plurality of end to end, longitudinal, parallel plunger pick bores 108 registering With the openings 98 of the plate 96, said plate 96 abutting against the inner end, of the plunger pick housing 102 as shown in Figure 2. Slidably reciprocable:

within the pick bores 108 are plunger picks 110, these being of elongated, cylindrical formation andzterminab ing at their outer, projecting ends in points 112. It will be understood, in this regard, that although conical points are shown on the picks, said points can be of any desired design and may be of the chisel type or, for thatV matter, of any other type found suitable for accom'- plishing the particular task with maximum eiciency. The plunger picks, in this connection, are interchangeable, so that the one tool can be provided with a number of diiferent sets of picks, each having a different typey the diameters of the pick bores, and by reason of this.

arrangement, there is created, as soon as the extension 114 of each pick moves during the retraction of the pick into the associated opening 98, a bui-fer space or air cushion surrounding the back end of the pick and designated at 115 in Figure 2. The purpose of this is to reduce shocks that might otherwise occur were the picks drawn back at high speed into engagement with the head plate 96. The air buffer spaces, it will be noted, are completely closed when the extensions 114 move into openings 9S, so as to cause air to be compressedV in said spaces to cushion the blow of the pick during its retraction, except for the provision of the small notches 100 communicating with the openings 98. These provide a small relief port for each air buffer space which, at the conclusion of the retraction of the pick, permits the `delayed escape of air from the air buier space so as to promote the cushioning action.

The picks are also reduced to a slight extent in diameter at their forward end portions as at 116, and formed in the main or large diameter portions of the picks are small, narrow, longitudinal slots 11S that open at one end upon the shoulder defined by the reduced diameter forward end portions 116.

The purpose of reducing the forward end portions of the picks in diameter relative to the diameter of the pick bores 1% is to provide an air buffer space not only at the back of the pick, but also at the front, so that again, shocks are not transmitted, when the picks are moved through their outstrokes, to the associated parts of the tool. The slots 118, in this connection, move intocornmunication with radial bores (Figure 4) communieating the center pick bore with the pick bores of the annular series. The slots 113 communicate with the bores 120 immediately prior to movement of the picks to the full limit of their outward strokes, to provide an Communicating between the pick bores of the annular series and the outer surface of the pick housing are radial passages 122, and extending about the pick housing, at the location where the bores 122 open at their outer ends, is a cylindrically shaped lter screen 124. This is of a porous fiber, through which air can escape at a limited rate, thus relieving the air butter spaces at the outer ends of the picks. The filter screen is encased by a filter cup 126, having circumferentially spaced, longitudinally extending slots 128 and openings 130 alternating with said slots (Figure l). The provision of the slots deines spring tongues on the cup, facilitating the application or removal of the same, and at the inner ends of the tongues, inwardly turned lips 132 are formed, engaging in circumterentially extending grooves formed in the outer surface of the pick housing to hold the cup in place.

In use, the tool is disposed adjacent a piece of work W having, for example, a deeply penetrating area of rust R varying in depth over its entire area. To remove the rust, the tool is positioned as shown in Figure 3, and when the motor is turned on, the piston 44 will reciprocate at high speed. Alternating pressure and vacuum conditions arc thus created in the chamber 22. When the piston moves through its pressure stroke from its Figure 2 to its Figure 3 position, air is compressed in the chamber 22, and overcomes the restraint of the spring 94 which ilattens somewhat as shown in Figure 3, causing the pressure valve disc 88 to be unseated. The compressed air is thus forced through the peripheral series of notches 90, and impinges against the inner end surfaces of the several plunger picks. The plunger picks are thus forced into their outstroke from their Figure 2 to the Figure 3 positions, against the area to be cleaned. It is important to note that some of the picks may move further than other picks, depending upon the contour of the work surface and the resistance encountered by the picks when they strike the work.

When the piston moves from its Figure 3 position to its Figure 2 position in its vacuum stroke, a vacuum condition is created in chamber 22, and at this time, valve disc 88 will seat as shown in Figure 2, while the restraint of spring 84 will be overcome causing the spring 84 to be flattened, thus drawing the suction Valve disc 86 off its seat and permitting the suction to be communicated through the ports 92 of valve disc 88, to the plunger pick bore. As a result, vacuum is created in each plunger pick bore, causing the pick thereof to be retracted to its Figure 2 position.

The valve assembly 82 has a particularly valuable characteristic, in that when the piston begins to move into its pressure stroke, spring 94 does not yield immediately. Instead, for a relatively minute period of time, the spring holds valve disc 88 in a seated position, causing pressure to be built up to the right of the valve disc in Figure 2. Further movement of the piston 44 through its pressure stroke causes spring 94 to' flex, so that the.

pressure is now transmitted to the plunger pick bores, causing the picks to be given a stroke of increased rapidity.

During the use of the tool, the same can be twisted or otherwise manipulated, to bring the picks to bear against different areas during the high speed reciprocation of the same.

The tool is particularly adapted for cleaning surfaces having uneven contours, concavities, conveXities, or other conformations which normally present diiiculties when a multiplicity of power operated cleaning elements are directed thereagainst in unison.

It is believed apparent that the invention is not necessarily confined to the specific use or uses thereof described above, since it may be utilized for any purpose to which it may be suited. Nor is the invention to be necessarily limited to the specic construction illustrated and described, since such construction is only intended to be illustrative of the principles, it being considered that the 6 invention comprehends any minor change in construction that may be permitted within the scope of the appended claims.

What is claimed is:

1. In a tool for cleaning residues, foreign deposits and the like from a work surface of the type comprising; a casing having a piston chamber, a piston reciprocating in the chamber to create alternating pressure and vacuum conditions therein and means for reciprocating the piston; a pick housing carried by the casing and having a plurality of pick bores communicating with said chamber; picks mounted in said bores for slidable reciprocation responsive to the creation of said alternating conditions in the piston chamber; and a valve assembly mounted in said chamber between the piston and pick bores and arranged to prevent communication between the chamber and pick chambers for a predetermined time interval during the initial movement of the piston in its pressure creating stroke, said assembly opening to communicate the chamber and bores during the remainder of the pressure stroke of the piston,

2. In a tool for cleaning residues, foreign deposits and the like from a work surface of the type comprising; a casing having a piston chamber, a piston reciprocating in the chamber to create alternating pressure and vacuum conditions therein and means for reciprocating the piston; a pick housing carried by the casing and having a plurality of pick bores communicating with said chamber; picks mounted in said bores for slidable reciprocation responsive to the creation of said alternating conditions in the piston chamber; and a valve assembly interposed between the piston and the pick bores, said valve assembly including a pressure valve disc unseating during the pressure receiving stroke of the piston to permit pressure to be transmitted from the chamber to the pick bores, and a vacuum valve disc unseating during the vacuum creating stroke of the piston to cause the creation of a vacuum in the pick bores responsive to the creation of a vacuum in said chamber.

3. In a tool for cleaning residues, foreign deposits and the like from a work surface of the type comprising; a casing having a piston chamber, a piston reciprocating in the chamber to create alternating pressure and vacuum conditions therein and means for reciprocating the piston; a pick housing carried by the casing and having a plurality of pickbores communicating with said charnber; picks mounted in said bores for slidable reciprocation responsive to the creation of said alternating conditions in the piston chamber; and a valve assembly interposed between the piston and the pick bores, said valve assembly including a pressure valve disc unseating during the pressure receiving stroke of the piston to permit pressure to be transmitted from the chamber to the pick bores, and a vacuum valve disc unseating during the vacuum creating stroke of the piston to cause the creation of a vacuum in the pick bores responsive to the creation of a vacuum in said chamber, the respective valve discs being spring loaded to resiliently and yieldably resist movement to their unseated positions,

References Cited in the le of this patent UNITED STATES PATENTS 848,459 Grant Mar. 26, 1907 974,267 Hennessy Nov. 1, 1910 1,024,395 Canty Apr. 23, 1912 1,408,176 HDoubler Feb. 28, 1922 1,585,740 Saulia May 25, 1926 1,813,546 Schindler .Tuly 7, 1931 1,857,138 Campbell May 10, 1932 2,070,552 Ohlsson Feb. 9, 1937 2,091,408 Lewis Aug. 31, 1937 2,343,137 Douglas Feb. 29, 1944 2,672,677 Arx Mar. 23, 1954

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