US800329A - Pneumatic tool. - Google Patents

Description

No. 800,329. PATENTBDSEPT. 26, 1905.

J. A. SHEPARD." PNEUMATIG TOOL. APPLICATION FILED DIEU.3, 1902.

2 SHEETS-SHEET 1.

WITNESSES:

ton, the exhaust-passages from the front end hereinafter and more ,NITEDJ fsfrnirns PATENT OFFICE.

JAMES A. SHEPARD, OF MONTOUR FALLS, NEW YORK, ASSIGNOR TO THEGENERAL'PNEUMATIO TOOL COMPANY, OF MONTOUR FALLS,

NEW YORK.

PNEUMATIC Tool..

Patented Sept. 26, 1905.

Application filed December 3, 1902. Serial No. l3 3,'75l0.

To all whom t may concern/.-

reciprocation of the piston being governed by van automatic valve the shifting'of which is controlled by the piston.

The object of my improvements is to so construct and arrange the admission and exhaust ports and passages and the automatic valve that the piston may be thrown forward with the full pressure of the live air upon-,it` and with a free exhaust from infront of thev pisof the cylinder being of such number and capacity as to permit of the passage of the Iair from infront of the piston without the least back pressure, to so arrange the said ports and passages that the piston will be returned with a slower stroke, and to so time the shifting of the valve as to cutoff the exhaust and admit air to the rear of the piston before it reaches the end of its rearward stroke in order to provide a cushion to prevent shock at this end of the piston-stroke. This and other novel features in the construction of my hammer will be fully described particularly pointed out in the claims. l

I attain my object by means of the construction and arrangement of the several parts of the hammer, as illustrated in the accompanying drawings, in whichl Figure 1 represents a transverse section of the hammer on linell in Fig. 5; Fig. 2, asimilar section on line 22 in Fig. 5;` Fig. 3, asect-ion on line 3 3 in Fig. 5; Fig. 4, a detail showing a section of the valve-box removed; Fig. 5, a plan View of the outer face of said valvebox; Fig. 6, a detail showing a transverse section of the valve, "and Figs. 7 and 8 details showing myimproved locking deviceby which theI parts of the hammer are secured together.

i throttle-valve. .boxis provided with four annular grooves,

Like characers of reference designate like parts in the several views.

A represents the barrel orcylinder of the tool, and B thev handle, these parts beingl united by meansof the coupling-sleeve O, which is screwed into the handle B, as indiicated. f In order" to hold these parts from jarring loose when the tool is in operation, l

provide the outer rim of the handle B with lserrations, as shown in Fig. 7 andinthe externall shoulder or liange on sleeve O in an inclined notch cut therein with slightlydove` ltailed sides is inserted a dog or lockingblo'ck D, provided with serrations to cor- Lrespond with those on vthe rim of handle B. ,Inl assembling the parts after the sleeve O isv Iset up tight .in handle B'the block D is in# serted, after which the sleeve O is given a slight backward turn to bring the teeth on I`block D into close engagement with those on- .handle B. The block is then held in place by ereason of theangle which its sides make with the horizontal faces of the teeth on handle B, and' it cannot be removed except by forcing.V the sleeve forward again to release the teeth.

Within the ,chamber formed between the endfof cylinder A andthe handle B is an annularvvalve-box E, the bore ofwhich is in axial alinement with that of the cylinder. This' valve-box is of smaller external diameter than3 the insideV diameters of. the sleeve O- and the handle B at thisI point, thereby forming an annu1ai--exhaustchamber F all around the valve-box, from which the exhaust-air passes: by way of port d. Fastened between the rear' face of valve-box E and the end of the cham-A ber F in handle B is a cap G, which fits over and around the cylindrical projection I at the rear of the valve-box, thereby forming two chambers- J and K, in thelatter'of which' reciprocates the enlarged head of the valve L. Surrounding cap Glin handle B is a'chambery H, intowhich leads the air-supply from the The inner wall of the valvewhich will hereinafter be designatedjas grooves l, 2, 3, and 4, beginning at the outer end of` the valve-box, as` indicated'in Fig." Hand the valve L is provided Awith/a groove Zof 'ajwidtlrY `suficientto placetwo'of the grooves in the:

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valve-box into communicationjwithonefanJ vIo other. This valve L is hollow and is provided with a series of holes or small ports at fr and s. (See Fig. 6.)

M is the piston, which is grooved at m for a purpose hereinafter to appear. rl `he end of the piston is provided with an annular bore P to receive the sleeve O, which projects from the block N, which closes the outer end of cylinder A. By this construction air will be trapped between the end of the piston and the block when the shank Q of a working tool is not in place in said block or has been thrown out to the extent of its stroke by the hammer In order that the shank Q, may be retained in block N when manipulating the hammer, l provide a split ring R in groove a, this ring after being sprung into said groove projecting inwardly,so as to engage the groove g in shank Q, this groove q being made of sufficient width to allow for the vibrations or reciprocations of the tool when struck by the piston. It will be understood that the groove n is of sufiicient diameter to allow for the spreading apart of the ring R when the shank Q, is forced into or out of the block N when inserting or removing it from the hammer.

I have shown the ring R and the groove n of such size that the ring R will be principally contained in the groove n, so that when the shank Q, of the working tool is withdrawn the ring R will be retained in the groove n. Also the groove n is shown in the bushing N. Obviously the groove n may be cut directly into the wall of the cylinder where a `bushing is not used to form the end of the cylinder. Also the groove n may be made shallow, while the groove g in the shank of the working tool Q may be made deeper, so that the ring R will be retained in the groove q. I do not, therefore, limit my invention to the precise arrangement shown in the drawings, but desire to cover, broadly, the use ot' the elastic ring and any arrangement of grooves suitable for a tool of lthe type described.

Referring next to the ports and passages by which air is admitted to and exhausted from the cylinder and the valve-box, Fig. 5 represents a plan view of either the outer face of the valve-box E or the inner face or end of cylinder A and shows the number and location of the several longitudinal passages in the valve-box and cylinder-walls leading from the cylinder to the grooves and chambers in and around the valve-box. rl`he admission-passages leading from chamber H to groove Z in valve-box E are indicated by a, there being four of these passages, as shown in Fig. 5. From groove 4 passages lead to ports near the outer end of the cylinder, these ports being in line with the inner end of sleeve O. (See Figs. l and There are four of these passages ,and they are of larger diameter than any of the other passages in order that the exhaust may be free from the outer end of the cylinder. From the inner end of the cylinder passages e lead to groove Q in the valvebox, and from groove 3 radial passages w lead out into exhaust-chamber F. 'lhere are l'our of these passages c, preferably ol slightly smaller diameter than passages o.

Referring to Fig. 2, wherein are shown the ports and passages for operating` valve li, f

indicates a passage running from chamber .l to the two ports .r/ and t, positioned as `shown, and vf is a passage leading' from chamber l( to a port slightly in advance of port /1f. From the port in line with port /t a passagej, (indicated in broken lines in Fig. 2,) leads to one of the exhaust-passages c. From the chamber l( a restricted passage /if (sec Fig. 3) leads to exhaust-chamber F, by which the outer end of this chamber K is always open to the exhaust.

Having thus pointed out thc locations ol the different ports and passages, the operation of the tool will be understood as follows: With the valve and piston in the positions shown in Figs. l and 2 the air will pass from chamber H through passages a and groove l in the valve-box to the rear of the piston, throwing the piston outward with the full force of the air. The air from in 'frontol the piston is exhausted by way of passages I), grooves 4 and 3 in the valve-box, and passages c into the exhaust-chamber F, whence it passes out through port (Z, the grooves 4. and 3 being placed in communication during this period by groove Z on the valve. As the pasges ZJ are large and numerous and the passage from the groove 4 to groove 3 around the valve is of corresponding area, the air will be exhausted from in front of the piston without back pressure and the full force of the live air-pressure will be expended upon the piston in delivering the blow at the end ol the piston-stroke.

Referring to Figs. Z and 3, when the rear end of the piston on its outward stroke has passed port g the live air from the supply will pass into passage f and thence to chamber J, where it will act upon the enlarged head of the valve to throw the valve outward into position for the return stroke of the piston. The air from in front o1 this enlarged head of the valve in chamber l( passes out through the small passage into exhaustchamber F. As soon as the valve is shifted into the position shown in Fig. 3 the live air from passages aand groove 1 will pass through the ports r into the interior of the valve and thence through the ports s to groove Ll and passages which carry it to the front end of the cylinder to throw the piston to the rear. During this rearward stroke of the piston the air is exhausted by way of passages 1 and grooves 2 and 3, which are now in communication by way of groove l on the valve to the passages c, leading to exhaust-chamber F. ln order that the force of the air for the return stroke may be reduced so as to give a slower return movement to the piston, ports r and s IOO IOS

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in the valve are restricted infarea, and Y.the

exhaust-passages e are also made smaller in diameter than the passages b. i i' Reducing the capacity of the passages 'e also .insures at all times some pressure at the rear -properly restrain the exhaust from the rear of the piston I make those portions of the passages e which are in the wall of the cylinder smaller in diameter andthe passages less in number than the portions of said passages which are in the valve-block. Bythis means a valve-block having ports e of suicient capacity to properly exhaust the air from the rear of a piston having a long stroke when used with a barrel of extremely short stroke will be properly modified in its action to suit Vthe needs of the shorter stroke, and perfect interchangeability of these partsin hammers o f all sizes is thus secured. LOne handle with a standard valve-block and valve may therefore be applied to cylinders of different strokes, and the number of standard parts for the purpose of interchangeability will be reduced to a minimum, resulting not only in economy in manufacture, but also in convenience in use.

Just before thepiston reaches the position shown in Fig. 2 passages f and j' will-be placed in communication by wayof port t and the groove m on the piston, thereby opening the chamber J to the exhaust,- since the passage j leads into one of the exhaust-passages 0, and as soon as the forward end of the piston has uncovered the port leading-to passage t' the liveair vwill Apass therethrough to the chamber K in front of the enlarged head of the valve L, thereby throwing the valve to the rear and closing off the exhaust from passages e and admitting air through passages t to throw the piston forward again.A As this shifting of the valve and the cutting off of the exhaustthrough passages e takes place before As the chamber K is open to the exhaust' at all times through the restricted passage-Za, the air after being admitted through passage z' to throw the valve to the rear will slowly escape through the saidpassage la; but the valve will stillbe held firmly seated in its rear-A ward position by reason of the live air which is now admitted to the cylinder between vthe forward face of the valve and the piston.'V It willtherefore ber'readilyunderstood that no Y iiuttering of the valve can take place at either stroke, since the valve will be held firmly seated by. the pressure either of the live air admitted between it and the piston'as soon as, it has been shifted to the rear or of the air behind it in chamberJ when the valve is in its forward position, the air from chamber K at this time having been exhausted throughI the passage la and the air in chamber J being trapped' therein during the return stroke of. the piston until the port has been placedfin communication with the exhaust-passage j by way of the groove m 'on the piston. It will be noted that there are three differential areas on the Valve L, the forward` face `of the valve being exposed directly to the ad- `of the piston when the port g is uncovered tov force the valve forward against the air-pressure in the cylinder, and the intermediate annular face at the forward side of the enlarged head of the valve, which is always exposed to vthe exhaust byway of restricted passage 7c vand intermittently exposed to the pressure of the air passing from. the. forward end of the` cylinder through passage t' when the piston is approaching the end of its rearward stroke.

Moreover, the valve when shiftingk travels inV the same direction in whichvthe piston is moving. From an inspection of Figs. 1. to 5 it will be seen that by reason ofthe axial. alinement of` roo the valve-box with the cylinder and the.

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inder at full pressureto drive the piston forwardand with reduced pressure atthe frontf end of the cylinder for the return stroke of thepiston. In Fig. 5 I have shown four admission-passages a inthe vvalve-box, four large passages 'b leading therefrom to the forward' end of the cylinder, and .four passages of intermediate size e for the exhaust from the rear end of the cylinder. Passages fdl, and j, which are utilized for shifting the valve, are of still smaller. diameter, as veryllittle air is required forI this purpose. p' p indicate sockets ,for dowel-pins, by which` thevalvebox and cylinder. arejfastened together in proper alinement. It will be eyident that by varying the. size and number/of the passages a, b, and e I may'attain Aany desired regulation in the, speed of. the piston travel in either. direction.

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On the outward stroke of the piston after the blow has been delivered and the forward end of the piston has closed the ports into passages b the air in front of the piston and between it and block N will be compressed by reason of the sleeve O and groove P, already referred to, so as to prevent a blow from the piston upon block N, and this provision for cushioning the forward end of the piston will also prevent a blow upon said block N when the shank of a tool is not in place within the socket.

I am aware that valved pneumatic hammers have been constructed with ports of diderent capacity, whereby the movement of the piston in one direction will be more rapid than in the opposite direction. Heretofore this has been accomplished by contracting the admission-ports, and is open to the objection that the piston is controlled by air under only slight pressure and the speed at which the piston makes its rearward stroke will be much more influenced by the amount of rebound from the working tool than by the quantity of air delivered through the ports. This is particularly noticeable when the hammer is used for driving rivets and also when the direction of the blow is upward. Vhile the rivet is soft and yields readily there will be very little rebound and a comparatively slow return of the piston. As the rivet cools the rebound increases, greatly increasing the velocity with which the piston returns, and consequently the number of blows struck in a given period and the recoil of the hammer. I have found in some cases that the rebound will cause a pressure beneath the piston less than atmospheric pressure. By my improvement the velocity of the rearward stroke is largely controlled by the exhaust from behind the piston, since the piston cannot return except against a heavy pressure until the pe riod necessary to exhaust the air behind it has elapsed. rIhe speed is therefore very nearly uniform under all conditions and is not sensibly affected by the position of the hammer or the amount of rebound. I do not claim, broadly, the use of ports of differing capacity leading to the respective ends of the cylinder; but the scope of my invention is restricted to the use of exhaust-ports of differing capacity in a valved hammer leading i' rom the respective ends of the cylinder and means for varying the exhaust function of the valve by varying the construction of the cylinders only.

Having thus described my improvements and pointed out the particular features which I deem to be novel and important, what I claim as my invention, and desire to secure by Letters Patent, is-

1. In an impact-tool, the combination of a cylinder, a reciprocating piston therein, and avalve to control the movements of the piston, said valve having differential pressure areas,

of which one of the smaller areas is constantly exposed to the intermittent pressure ol the motive fluid in the cylinder acting on one side of the piston, the greater area being intermittently exposed to the pressure of the niotive fluid acting upon the same side of the piston, and au intermediate area being intermittently exposed to the pressure oi the motive iiuid acting upon the opposite side ol the piston.

2. In an impact-tool, the combination of a cylinder, a reciprocating piston therein, and a valve to control the movements of the piston, said valve having differential pressure areas, of which one of the smaller areas is constantly exposed to the intermittent pressure of the motive fiuid in the cylinder acting on one side of the piston, the greater area being intermittently exposed to the pressure of the motive iuid acting upon the same side of the piston, and an intermediate area being intermittently exposed to the pressure of the motive iiuid acting upon the opposite side ofthe piston, the admission to said 4last two areas being controlled by the piston through passages leading thereto from the cylinder.

3. In an impact-tool, the combination oi a cylinder, a reciprocating piston therein, and avalve to control the movements of the piston, said valve having differential pressure areas, of which one of the smaller areas is constantly exposed to the intermittent pressure of the motive iiuid in the cylinder acting upon one side of the piston, the greater area heilig intermittently exposed to the pressure of the niotive iiuid acting upon the saine side of the piston, the admission and exhaust to and from said area taking place through passages controlled by the piston, and a third and intermediate area being intermittently exposed to the pressure of the motive Huid acting upon the opposite side of the piston, admission to this last area being by way of a passage controlled by the piston, and exhaust therefrom being open at all times through a contracted passage.

4. In an impact-tool, the combination of a cylinder, a reciprocating piston therein, a valve-box in axial alinement therewith, adifferential pistonvalve therein, the forward face of which controls the admission of motive fluid to the cylinder at the rear of the piston and is constantly exposed to the intermittent pressure of the motive fluid on that side of the piston, the rear face of said valve being of larger area and intermittently exposed to the pressure of the motive iiuid acting upon the same side of the piston and to the exhaust by way of passages controlled by the piston, an intermediate face on said valve being intermittently exposed to the pressure of the motive fluid acting upon the forward end of the piston by way of a passage opened by the piston during its rearward stroke, exhaust from said face being open at all times through IOO IOS

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a contracted passage, and ports and passages leading to and from the ends of the cylinder controlled said valv-e. y

5. In an impact-tool, the combination of a cylinder, a reciprocating piston" therein, a

grooved valve-.box in axial alinement therewith, a cylindrical extension ofA larger ,bore at the rear of the valve-box, a cap-piece surrounding said `e'xtenslon and separatlng it -from the source of motive-fluid supply, a

grooved piston-valve having an enlargedhead 4reciprocating in the valve-box and its extension, passages leading from each side of the i valve-head to the cylinder whereby admission and exhaust vof the motive fluid to and from the opposite faces of said head are controlled by the piston, portsand passages leading from the ends of the cylinder to grooves in the head to the cylinder and the exhaust-outlet whereby admission and exhaust of the motive iuid to and from said chambers are controlled by the piston, the first groove in the valvebox nextl the `cylinder being connected with the source of Huid-su pply and being opened directly to the cylinder when the valve is retracted, thesecond and fourth grooves in the valve-box being connected by passages with the cylinder at its rear and forward ends respectively, and the third groove being connected with the exhaust-outlet, ports in the valve'whereby the first and fourth grooves are placed in communication through the valve when in its forward position, and a groove on the valve whereby the second and fourth grooves are placed in alternate communication with thethird groove.

7. In an impact-tool, the combination of a cylinder, a reciprocating piston therein, a valve-box havingagrooved bore in axial alinement therewith, a plurality of passages of comparatively large diameterv leading to one of said grooves from one end of the cylinder,

I .one or more passages of smaller capacity leading from the other endof the cylinder to another of said grooves, admissionand exhaust v passages leading to and from other of said grooves, and a valve to control the intercommunication 'of said grooves shifted by the motive iuid acting upon the valve through passages controlled by the piston, the motive fluid being admitted directly to the cylinder for one'stroke of the piston and by wayof; l

contracted ports'leading through a chamber in the valve for the return stroke.

8. In an impact-tool, the combination of a cylinder, a reciprocating piston thereingzports and passages of different capacity leading to" avalve-chamber from opposite ends of the cylinder, a valve in said chamber whereby the `motive fluid is admitteddirectly to one endgof the cylinder and indirectly through contracted passages to the other end, the passages from'-I the' two ends of the cylinder being placed by thevalve in alternate communication with a common exhaust-outlenwhereby the piston may be moved at high velo'city and without back pressure ,in one direction and at a slower and restrained speed in the oppositedirection.

9. Inan impact-tool, the combination of a Cylinder, `a piston reciprocating therein, -a valve-chamber, one or more passages leading from a source of fluid-supply to a circumferential port or row of ports in the valve-chamber, and a valve in said chamber whereby said port or ports are uncovered to admit the motive iiuid directly to one side vof the piston when the valve is moved in one direction,` and whereby said port or ports are placed in communication with the other side of the piston by way of a port or ports leading to a chamber within the valve and thence by ports and passages to thecylinder when the valve is moved to its other position.

10. In an impact-tool, the combination ofv a cylinder, a piston reciprocating therein, a valve-chamber provided with a ser1es of c1rcumferentlal grooves or ports, passages leading'therefrom to the source of motive supply,

to the exhaust-outlet, and `to the cylinder at each sideof the piston, and a hollow grooved valve reciprocating in said chamber, wherebyl certain of the grooves or ports in the chamber are placed in intercommunication through ports leading to and from the interior of the valve, and others of said groovesv or ports are placed in intercommunication by the groove IOO IIO

on the valve, as the valve is shifted from one position to the other.

11. In an impact-tool, the combination with I thecylinder, piston and controlling-valve, of a block or bushing'closing the outer end of the cylinder and adapted to receive the shank of the working tool, a sleeve projecting into the cylinder from said block, an annular bore in the endof the piston to fit said sleeve, and a port or ports in said cylinder at or near the inner extremity of said sleeve leading to the chamber of the controlling-valve, as and for the purpose set forth.

12. In a tool of the type described, the combination, with the barrel and handle, of a coupling-sleeve having an external flange with a notch or recess running across its outside periphery, a locking block or dog fitted in s aid recess and provided with serrations adapted to be brought into engagement with correspending serrations on the rim of the handle when the parts are assembled.

13. In a tool of the type described, the combination, with the barrel and handle, ot' a coupling-sleevehaving an external flange With a notch or recess running across its outside periphery, a locking block or dog fitted in said recess and provided with serrations, the contact-faces of which are set at an incline to the guiding sides of the notch or recess, and co1'- responding teeth on the rim of the handle to be engaged thereby when the parts are assembled.

14. In a tool of the type described, alocliing device for the screw-coupling whereby the handle and cylinder are united comprising la block or dog movably mounted in a socket or recess in one member of the coupling and provided with .serrations adapted to engage corresponding serrations upon the other member, the interlocking faces of said serrations Where they come into contact being set at an angle to the guiding sides of said socket in opposition to the line of Withdrawal of the locking-block, whereby the coupling members must be set up tighter by a partial rotation in order to release said block.

15. In an impact-tool, the combination of a cylinder, a reciprocating' piston therein, a valve to control said piston operated by fluidpressure, a passage or passages or comparatively large capacity leading' from the lorward end of the cylinder to the valve and thence to the exhaust, a passage or passages ol less eapaeity leading from the rearward end ol the cylinder to the valve and thence to the exhaust, wheeby the piston may he moved at high velocity and with slight back pressure toward the working tool and at a slower and restrained speed against hack pressure away from the working tool, an appreciable pressure being maintained at all times at the rear of the piston.

In testimony whereoil I have al'lixed my signature in presence of two witnesses.

JAMES A. SHEPARD.

I/Vitnesses:

Jos. VVoLvERToN, W. H. SHEPARD.

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