US3535983A

US3535983A - Tandem piston filer/sander tool

Info

Publication number: US3535983A
Application number: US772512A
Authority: US
Inventors: Kenneth A Mchenry
Original assignee: Chicago Pneumatic Tool Co LLC
Current assignee: Chicago Pneumatic Tool Co LLC
Priority date: 1968-11-01
Filing date: 1968-11-01
Publication date: 1970-10-27
Anticipated expiration: 1987-10-27

Description

States tent Inventor Kenneth A. Mclllenry Clinton, New York Appl. No. 772,512

Filed Nov. 1, 1968 Patented Oct. 27, 197 0 Assignee Chicago Pneumatic Tool Corny New York, New York a corporation of New Jersey TANDEM PISTON FlLER/SANDER TOOL 4 Claims, 6 Drawing Figs.

US. Cl 91/309, 91/313,91/329, 51/170.3,173/170 Int. Cl F011 25/06, F011 15/18 Field of Search ..91/ 179 (Cursory), 304,, 329, 309, 313:(1nquired purser) 173; 51/1703 (Cursory) References Cited UNITED STATES PATENTS 1,243,199 10/1917 Miller 91/329 2,333,316 11/1943 Klossner 91/304 2/1953 Sprague et al 9l/304 Primary ExaminerPaul E. Maslousky AttorneyStephen J. Rudy ABSTRACT: A pneumatically powered reciprocating tool having utilization in various fields, but finding special use in the automotive industry as a surface working tool. It includes a housing having appropriate hand grips for maneuvering the tool. The housing supports a tool carrier-plate adapted to accommodate a reciprocable tool, such as a filer or sandpaper carrier. The carrier-plate is reciprocable by means of a pair of pneumatically operable pistons axially coupled in tandem relation so as to move in unison. Operating air is fed to the tool through a manipulative throttle valve and is caused to be ap plied alternately to a pair of opposed end faces of the pistons by means of a pneumatically shiftable distributing valve. The latter is caused to be shifted for this purpose by means of a pushrod valve which moves as a unit with the pistons. Reciprocation of the pistons and, as a consequence of the carrierplate, and automatic operation of the distributing and pushrod valves continues until the operator releases the throttle valve to closed condition.

Patented Oct. 27, 1970 Sheet 1 of 2 ATTORN EY TANDEM PISTON FILER/SANDER TOOL BACKGROUND OF THE INVENTION This invention relates to the art of reciprocating surface working tools of a type driven by means of a pair of pneumatically operable pistons.

The general object of the present invention is to provide a reciprocating surface working tool having a simplified operating mechanism in which a pair of tandem pistons are alternately pneumatically operable to reciprocate a tool carrier-plate.

A particular feature of the tool of the present invention is its simplified mechanism in which the application of pneumatic operating fluid is automatically applied, upon operation of a throttle valve, alternately to each of the pistons as long as the throttle valve is held open.

Another special feature of the tool lies in the tandem arrangement of its reciprocating pistons as well as in the arrangement of a pair of valves which operate automatically as a consequence of movement of the pistons to cause application of operating air alternately to the pistons. The tandem ar rangement of the pistons enables both pistons to move in unison as operating air is applied to one or the other of them. This arrangement enables a simplified housing to be used having a desirable narrow structure.

The particular arrangement of the valves and pistons has a further distinct advantage in that the tool has a positive and immediate starting operation regardless of the last stopped position of the pistons.

SUMMARY OF THE INVENTION In accordance with the invention. there is provided a pneumatically powered surface working tool comprising a pair of axially aligned piston chambers, a partition block separating the chambers from one another, a separate piston reciprocable in each chamber, a surface working tool carrier-plate having its longitudinal axis parallel to the line of travel of the pistons, means coupling the pistons in tandem relation with each other and to the carrier-plate for movement of the pistons and carrier-plate in unison, a distributing valve pneumatically shiftable to cause operating air flow alternately to the piston chambers, and a push-rod valve having movement as a unit with the pistons controlling pneumatic shifting of the distributing valve.

BRIEF DESCRIPTION OF THE DRAWINGS In the accompanying drawings:

FIG. 1 is a view in longitudinal section of a tandem piston pneumatic surface working tool embodying the invention;

FIG. 2 is a bottom plan view of FIG. 1;

FIG. 3 is a left or front end view of FIG. 1 with some parts broken away:

FIG. 4 is a schematic view showing the mechanism of the tool in its last stopped condition, in which condition the pistons have stopped about midway of their stroke to the right;

FIG. 5 is a schematic view showing the pistons at the end of their stroke to the right, and showing the distributing valve in a shifted position preparatory to causing application of live air to the left piston member to efi'ect a leftward stroke of the pistons; and

FIG. 6 is a schematic view showing the pistons at the end of their leftward stroke and showing the distributing valve in a shifted position preparatory to causing application of live air to the right piston member to effect a rightward stroke of the pistons.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT In the accompanying drawings is disclosed a pneumatically powered reciprocating surface working tool. It includeds an elongated housing 11 having a main hand-grip 12 bolted upon its rearward area and having an auxiliary hand-grip 13 mounted upon its forward area. A manipulative throttle valve 14 is incorporated in the housing. The valve is operable to feed operating air from a live air supply connected inlet 15 to piston and valve mechanism 16 incorporated in the body of the housing to cause reciprocation of a tool carrier-plate 17 located externally at the bottom of the housing. An abrasive tool, such as a file 18, is shown bolted to the underside of the carrier-plate. It is understood that a sandpaper carrier (not shown) or other appropriate reciprocable operating tool may be selectively affixed to the carrier-plate 17 in lieu of the file 18.

Angle or L-brackets l9 bolted to opposite sides of the housing have inturned legs 21 upon which a pair of longitudinally extending ofiset shoulders 22 of the carrier-plate are supported as the carrier-plate is relatively reciprocated. The housing has a flat bottomed surface 23 to the forward area of which is bolted a pair of parallel guide blocks 24, which blocks are separated from one another by a space defining a longitudinal track 25 for guiding a forward pilot member 26 of the carrier-plate. A second pair of guide blocks 20 is similarly bolted to the rear underface of the housing, and provides a similar track 27 for a rear pilot member 28 of the carrierplate. Tracks 24 and 27 are axially aligned. The forward pilot member 26 is of L-form having one leg riveted to the top forward surface of the carrier-plate and slidable in the track 25. An upright leg 31 of the pilot member projects with a slide fit through a longitudinal bottom slot 32 of the housing into the forward area of a forward piston chamber 33. The other pilot member 28, also of L-form has a leg riveted to the top rear surface of the carrier-plate and is slidable in track 27. It also has an upright leg 35 projecting with a slide fit through a rear longitudinal bottom slot 36 of the housing into the rear area of a rear piston chamber 37. Piston

chambers

33 and 37 are axially aligned.

A pair of axially aligned

pistons

38, 39, is arranged in the housing. The

pistons

38 and 39, respectively operable in the forward and rear piston chambers, are coupled in tandem relation and are reciprocable in unison to transmit reciprocating movement through the

pilot members

26 and 28 to the carri er-plate 17. Each piston has a bossed end 21 abutting the inner face of the upright leg of the corresponding pilot member. A push-rod valve 42 having longitudinal sliding operation in a valve block 43 separating the piston chambers has one end projecting into the forward piston chamber 33 that abuts at all times an opposed face of piston 38. The opposite end of valve 42 projects into the rear piston chamber 37 and at all times abuts the opposed face of the rear piston 39. In this arrangement, the push-rod valve 42 maintains both pistons at all times in fixed axial spaced relationship to one another and in abutment with the

pilot members

26 and 28.

An air distributing spool valve 46 is pneumatically shiftable back and forth in the valve block 43 to cause feeding of inlet air alternately to the piston chambers. As best seen in the schematic showing of FIG. 4, the distributing valve 46 has obtained a shifted position in which it permits flow of inlet air to the rear piston chamber 37 to drive the rear piston 39 and, as a consequence, the carrier-plate l7 rearwardly to the right. The distributing valve 46 has a reversely shifted position, as best seen in FIG. 5, in which it permits flow of inlet air to the forward piston chamber 33 to drive the forward piston 38 and, as a consequence, the carrier-plate forwardly to the left. As each piston is pneumatically driven, it acts through the

pilot members

26 and 28 and through the connecting carrier-plate I7 to draw the other piston together with the pushrod valve 42 along with it.

The pushrod valve 42 controls pneumatic shifting of the distributing valve. It moves in unison with the pistons. As it moves, it controls alternate application of inlet air and exhaust to the left end 62 of the distributing valve 46 to effect shifting of the latter from one position to the other.

A particular advantage of the tool, as will be brought out later herein in a summary of its operation, is that its piston and valve mechanism 16 will start operating immediately upon application to it of inlet air, regardless of its last stopped condition. The tool does not require shaking or maneuvering in any manner to reposition its valves or pistons to enable it to commence operating.

In summary of the operation of the tool, reference is now directed particularly to the several schematic views of FIGS. 4-6. When last stopped, the piston and valve mechanism 16 of the tool obtained the condition shown in FIG. 4. Operation of the the tool is begun by manipulating the throttle valve 14 to open condition; and operation of the tool continues automaticaily as long as the throttle valve remains open. In FIG. 4, the distributing valve 46 is positioned at the left end of its chamber in abutment with an end stop 47; and the pistons are midway of their stroke toward the right or rearward direction. Air from the inlet passage 10, which is connected with the throttle valve 14, now enters the distributing valve chamber over

branch passages

49 and 50 to apply pressure against the lands 51, 52, and 53, causing the valve to remain pneumatically unbalanced in its left position. The vent 66 serves to subject the small diameter end of the distributing valve to atmosphere pressure. Inlet air now flowing to the right end of the distributing valve chamber flows over a passage 54 to move piston 39 to the right. The carrier-plate l7. piston 38 and pushrod 42 follow in unison the movement of piston 39. Air trapped in the left or forward piston chamber 33 is exhausted over a passage 55 communicating at this time around an annulus 56 of the distributing valve with an exhaust passage 57. After a predetermined extent of movement of the piston 39 to the right, an annulus 58 of the pushrod 42 uncovers and communicates a passage 59 with a passage 61 to cause application of inlet air to the left end 62 of the distributing valve. This pneumatically unbalances the distributing valve causing it to shift to its right position in abutment with the stop 63, as in FIG. 5, and the piston stroke or movement of the pistons toward the right then stops in the FIG. position.

In the FIG. 5 position the shifted distributing valve now communicates the passage 54 from the piston chamber 37 around the annulus 56 with exhaust passage 57 and connects passage 55 from the left piston chamber 33 around the annulus 64 with the branch inlet passage 49. Inlet air now being applied over the branch passage 49 forces the forward or left piston 38 to the left causing the carrier-plate 17, the right or rear piston 39 and the pushrod 42 to move to the left in unison with it. After a predetermined extent of movement of the pushrod to the left, as indicated in FIG. 6, the annulus 58 of the pushrod 42 uncovers and communicates the passage 61 with exhaust passage 65 to allow air pressure at the left end of the distributing valve 62 to escape. The distributing valve accordingly becomes pneumatically unbalanced in a leftward direction and is forced to its position at the left end of its chamber in abutment with the stop 47, as in FIG. 6. As a consequence of the distributing valve shifting to the left, the passage 55 from the left piston chamber 33 is connected by annulus 56 to exhaust 57, and the right piston chamber 37 is again connected over the passage 54 with the inlet branch 50 causing termination of the piston stroke to the left. This shifting of the distributing valve 46 and consequent reciprocation of the

pistons

38 and 39 continues automatically until the operator releases the throttle valve to closed condition.

It is to be noted that here the

piston chambers

33 and 37 are defined by means of a bore extending axially through the housing 11, intermediately of the ends of which bore the partition block 43 is tightly fitted. The opposite ends of the bore are respectively headed by means of a removable cap 67 and an end portion of handgrip 12.

I claim:

1. A pneumatically powered surface working tool comprising a housing having a pair of axially aligned piston chambers, a valve block contained entirely within the housing partitioning the chambers from one another, a separate piston reciprocable axially in each chamber, a surface working tool carrier-plate having its longitudinal axis parallel to the line of travel of the pistons, means coupling the pistons in tandem relation with each other to the carrier plate for reciprdcation of both pistons and earner-plate in unison and for restraining the carrier-plate against angular movement, a distributing valve within the valve block pneumatically shiftable to cause operating air flow alternately to the piston chambers, and a pushrod valve in the valve block having movement as a unit concurrently with both pistons controlling pneumatic shifting of the distributing valve.

2. A pneumatically powered surface working tool comprising a housing having a pair of axially aligned piston chambers, a partition block intermediately of the housing spacing the chambers from one another, a separate piston reciprocable in each chamber, a surface working tool carrier-plate located externally of the housing having its longitudinal axis parallel to the line of travel of the pistons, means coupling the pistons in tandem relation to each other to the carrier-plate for reciprocation of both pistons and the carrier-plate for reciprocation of both pistons and the carrier-plate as a unit, an operating air supply inlet passage in the housing, and valve means arranged in the partition block having communication with the inlet passage for causing flow of operating air alternately to the piston chambers, wherein the piston chambers are defined by portions of a bore which extends axially through the housing, the partition block is fitted intermediately of the ends of the bore, a removable cap heads one end of the bore. and a removable handle heads the opposite end of the bore.

3. A pneumatically powered surface working tool as in claim 2, wherein the coupling means includes a bracket mounted to one end of the carrier-plate and projecting through a longitudinal slot of the housing into the v piston chamber into engagement with one of the pistons. a second bracket mounted to an opposite end of the carrier-plate projecting through a second longitudinal slot of the housing into the other piston chamber into engagement with the other piston, and a pushrod slidable in the block maintaining the pistons in a fixed axially spaced relation to each other.

4. A pneumatically powered surface working tool comprising a pair of axially aligned piston chambers, a valve block partitioning the chambers from one another, a separate piston reciprocable in each chamber, a surface working tool carrierplate having its longitudinal axis parallel to the line of travel of the pistons, means coupling the pistons in tandem relation with each other to the carrier-plate for reciprocation of both pistons and carrier-plate in unison, and a distributing valve within the block pneumatically shiftable to cause operating air flow alternately to the piston chambers, the coupling means including a pushrod valve controlling pneumatic shifting of the distributing valve, the pushrod valve being axially slidable in the partition block and having its ends at all times in abutment with opposed inner faces of the pistons, and a pair of brackets each fixed to an opposite end area of the carrierplate and each bracket being at all times in abutment with the outer end face of a separate one of the pistons.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 35,983 Dated t er 27, 1970 Kenneth A. McHenry Inventor(s) It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shovm below:

Column 1, line 72, "includeds" should read includes Column 3 line 8, "of the the tool" should read of the tool line 54, "inlet branch 50" should read inlet branch passage 50 Column 4, lines 27 and 28, cancel "for reciprocation of both pistons and the carrier-plate".

Signed and sealed this 20th day of April 1971.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. WILLIAM E. SCHUYLER, JR. Attesting Officer Commissioner of Patents USCOMM-DC 003764 59 FORM PO-IOSD (10-69) us, r-ovnuuzm rnm'rmc ornc: 1 an mun-an