US1888790A - Power hammer - Google Patents

Description

c. B. coATEs POWER HAMMER Nov. 22, 1932.

Filed Feb. 16, 1928 @M www A TTORNE Y.

Patented Nov. 22j,

Unirse stares Param OFFICE CHARLES B. COATES, OF CLEVELAND, OHI, ASSIGNOR TO CHICAGO PNEUMATIC TOOL COMPANY, OF NEN YORK, N. Y., A CORPORATION F NEW JERSEY POWER HAMMER Application led February 16, 1928. Serial No. 254,845.

i Thisinvention rela-tes to powerr hammers generally but has been developed with particular attention to portable or hand operated hammers,such as are actuated by an electric motor attached to the hammer or by a ilexible shaft driven by a more remote source of power. i

One object of the invention is to increase the efficiency of power hammers generally.

Another object is to simplifythe construction and to reduce the lubrication problem. Another object is to cut down the weight and size of the portable power hammer. @ther objects will. beapparent from the detail-ed description which follows. l

In order to illustrate the invention one concrete embodiment thereof is shown in the accompanying drawing in which:

Fig. 1 is a side lelevational view largely in vertical section to show the details of the hammer; f Y

F ig. 2 is a fragmentary vertical sectional view 0fl the hammer and associated parts showing th-e relative positions at the end of the power stroke.

' In the embodiment of the invention chosen for the purpose of illustration the hammer consists ofa barrel 3 bored out axially to providea piston chamber within which reciprocates a free hammerV piston 4, the movement of which is controlled andactuated by a cylinder 5 of substantial length whichV telescopes over barrel 3 with aclose sliding iit and has limited reciprocal movement relative to the barrel.

is closed and cooperates with the top of barrel 3 to provide a chamber 6 of relatively large diameter as compared with piston chamber 3a.

to By preference barrel 3 extends within a shell 7 to which it is iiXedly secured in any suitable manner, as by a threaded connection at 8. The lower end of shell 7 may be split and provided with a clamping bolt 9 to lock barrel 3 securely in place. The proximate end of the barrel may have a bushing 10 pressed therewithin to receive the shank end of a working tool, such as a drill bit or chisel A, and to dispose the shank in position to receive the blows of hammer piston 4. The

The upper end of cylinder 5A 'the bulk and weight of the tool to a minimum.

To this end a crank shaft 12 is disposed trans'- versely within shell 7- closely adjacent the upper end of barrel 3, the shaft being journaled in bearings 13 and 14 at oppositesides of shell 7. The connection between the crank shaft 12 and cylinder v5 preferably takes the form of a Scotch yoke7 spaced loops or yoke portions 5a having aligned openings being formed upon the closed head portion of cylinder 5.

i TWhile shaft 12 may be arranged to be driven directly from any suitable source of power, it is preferable in a tool of the portable type'havingits own pow-er means to provide for gear reduction between the power shaft and the crank shaft. To this end crank shaft 12 is provided with a large gear 15 ar,- ranged to mesh with pinion teeth upon a power shaft 1G projecting within shell 7. Strength issecured by forming gear 15 integral with shaft 12 and compactness is at'- tained by makingthe gear cup-shaped and at least partlyl enclosing bearing 14 for `the proximate. end of the shaft. A counter balance 17 may be provided on a ring having a press fit upon shaft 12 adjacent gear 15.

llVhile power shaft 16 may be driven by a flexible shaft or other suitable means, it is preferable in small portable hammers to make the same an extension of the rotor shaft for an electric motor 18 supported in a Casing 19 secured to shell 7. By preference a transfer 90 plate 20 is interposed between motor casing 19 and shell 7 and this transfer plate may close an opening in shell 7 in line with shaft 12 and through which the latter may be withdrawn. In this construction the ltransfer plate supports bearing 14. v The tool is com# pl-eted by a handle 21, which in the present instance is secured both tomoto'r casing 19 and shell 7. The power cable 22 to motor 18 may be connected to handle 21 which may 100 stroke, ports b are closed and the air in chamber G is compressed causing hammer piston 4 to be forced downwardly by the air pressure on its upper end. rl`he area of the compression chamber 6 is so much larger than the area of the piston that the latter moves much farther' and faster on its downward stroke thandoes cylinder 5and it approaches the shank of the workingv tool with con,- siderable pressure back of it. d ust before the blow is struck (Fig. 2) piston 4 uncovers one or more radial ports 3b with which a corresponding number of ports 5c in cylinder 5 register when the cylinder is at the lower limit of its stroke. rlhis relieves the pressure in chamber 6 and the upper portion of piston chamber '3a by permitting the same to discharge into the space within shell Y. As cylinder 3 begins its rearward stroke ports 5c pass out of register with ports 3b and the suction produced in chamber 6 in cooperation with the atmospheric pressure, which has access to the lower end of piston l through ports ll, causes the return movement of piston l which continues until the suction pressure in chamber 6 is broken by the uncovering of ports 5b whereupon piston -t is ready for its power stroke, thus completing the cycle.

The described arrangement of axially spaced ports 5?) and 5c in cylinder 5 in conjunction with the enclosed space atatmospheric pressure within shell 7 notonly insures positive movement of piston l in both directions but keeps all dust and dirt out of the reciprocating parts of the hammer. The differential areas of hammer piston 4l and cylinder 5 as well as the proper positioning of ports 5b, 5c and SZ) are very important in securing efficient operation of the hammer. ln a practical embodiment of the invention as disclosed the stroke of cylinder 5 is {B- of an inch while the stroke of piston 4: is from 1/2 to fig. The blows are rapid and are much-more powerful than it has been possible to secure with piston driven hammers of this general type.

` The compactness and short stroke of the moving parts assist materially in reducing both wear and lubrication troubles. ln order to maintain a tight seal between cylinder 5 and fixed barrel 3, as well as to insure proper 4 lubrication of the same, the barrel is providedv at a point always covered by cylinder 5 with a deep groove 23 of substantial width, which is filled with suitable packing material 2li, such as cotton, which is saturated with lubricant;

While the invention has been herein disclosed in what is now considered to be its preferred form, it is to be understood that the invention is not limited to the specific details thereof, but covers all changes, modifications and adaptations within the scope of theappended claims.

l claim as my invention:

1. A power hammer comprising a barrel, a piston slidable therein, a cylinder enclosing said barrel and having a bearing upon the exterior of the latter, and means for reciprocating said cylinder upon said barrel.

2. A power hammer comprising a fixed barrel, a piston slidable therein, a cylinder i,

cooperating with said barrel to provide an expanding and contracting chamber above said barrel.

3. A power hammer 'comprising a fixed barrel, a piston slidable therein, a cylinder cooperating with said barrel to provide an expanding and contracting chamber above said barrel, and means for admitting air to said chamber in one position of said parts.

t. A power hammer comprising a fixed barrel, a piston slidable therein, a cylinder cooperating with said barrel to provide an expanding and contracting chamber above said barrel, and means for releasing air from said chamber in one position of said parts.

l5. A ower hammer comprising a fixed barrel, a piston slidable therein, a cylinder cooperating with said barrel to provide an expanding and contracting chamber above said barrel, and means controlled jointly `by said piston and by said cylinder for releasing air from said chamber in one position of-said parts.

6. A power hammer comprising a fixed barrel, a piston slidable therein, a cylinder cooperating with said barrel to provide an expanding and contracting chamber above said barrel, and cooperating means on said cylinder and said barrel forestablishing com- Yitc ila

mimication with said chamber and surround- Y ings in certain positions of said parts.

7. A power hammer comprising a barrel, a piston slidable therein, a cylinder of substantial length having a closed end and sleeved over said barrel with a close sliding tit, means for reciprocating said cylinder upon said barrel, and means including ports in said cylinder for establishing communication with the'chamber formed by the closed end of the cylinder in certain positions of the latter.

8. A power hammer comprising a barrel, a piston slidable therein, a cylinder of substantial length having a closed end and sle-eved over said barrel with a close sliding lit, means for reciprocating said Ycylinder iis upon said barrel, said barrel having an annular groove in its exterior in a position to be covered at all times by said cylinder, and lubricant in said groove.

9. A power hammer comprising a shell, a barrel secured within said shell, a hammer piston reciprocable within said barrel, a cylinder of substantial length having a closed end and sleeved over said barrel with a close sliding fit, means for reciprocating said cylinder over said barrel for expanding and contracting the chamber formed therebetween by the closed end of the cylinder, and means controlled by said cylinder for establishing conimunication between said chamber and the interior of said shell. i

10. A power hammer comprising a` shell, a barrel secured within said shell, a hammer piston reciprocable within saidbarrel, a cylinder of substantial length having a closed end and sleeved over said barrel with a close sliding fit, means for reciprocating said cylinder over said barrel for expanding and contracting the chamber formed therebetween by the closed end of the cylinder, and means including axially spaced ports in said cylinder for establishing communication between said chamber and the interior of said shell in a plurality of positions of said cylinder.

11. A power hammer comprising a shell, a barrel secured within said shell, a hammer piston recipiocable within said barrel, a cylinder of substantial length having a closed end and sleeved over said barrel with a close sliding fit, means for reciprocating said cyl-Y inder over said barrel for expanding and contracting the chamber formed therebetween by the closed end of the cylinder, said barrel having one or more radial ports therein under control of said piston, and said cylinder having one or more ports arranged to register with said barrel ports in one position of said cylinder.

12. A power hammer comprising a shell, a barrel secured within said shell, a cylinder sleeved over said barrel with a close sliding fit, a crank shaft journaled in said casing transversely above said barrel and closely adjacent thereto, a driving connection between said shaft and said cylinder, and means for rotating said shaft.

13. A power hammer comprising a shell, a barrel secured within said shell, a cylinder sleeved over said barrel with a close sliding fit, a crank shaft journaled in said shell transversely above said barrel and closelyY adjacent thereto, a Scotch yoke connection between said shaft and said cylinder, and a power shaft entering said shell and arranged to rotate said crank shaft. j

14E. A power hammer comprising a shell, a barrel secured within said shell, a free hammer piston reciprocable in said barrel, a reciprocable member cooperating with said barrel for actuating said piston, a shaft extend- 'ing ltransversely above said barrel and closely adjacent thereto, a driving connection between-"said shaft andsaid member, 'bearings for said shaft onopposite sides of said shell, a powershaft projecting within said shell, and driving connection between said first named shaft and' said power shaft including acup shaped gear on said first named shaft at least partly enclosing one of said bearings. 1,15.` In apower hammer, in combination, a shell having an end opening and a side opening, a barrel insertable within said shell shaft and driving connection for said cylinder insertable through said side opening.

16. In a power hammer, in combination, a shell having an end opening and a side opening, a barrel insertable within said shell through said open end `and adapted and arranged to close said open end and to be fixedly secured therein, a reciprocable cylinder on said barrel withdrawable with the latter through said end opening, a crank shaft and driving connection for said cylinder insertable through said side opening, a transfer plate secured to said shell for closing said opening and providing a bearing for said shaft, and a motor secured to said plate and arranged to drive said shaft.

17. A power hammer comprising a fixed barrel, a hammer piston slidable therein, a cylinder in telescoping relation with said barrel to provide an expanding and contracting chamber above the latter to edect movement of said piston, and means disposed in the telescoping-zone of said barrel and of said cylinder for lubricating the same.

18. A power hammer comprising cylindrical members in telescoping relation, the inner of 'said members being fixed and the outer member movable to provide an expanding and contracting chamber above said fixed member, and a hammer piston slidable within said inner member and moved as a result of the variations in said chamber, one of said members having a recess for lubricant in its telescoped portion.

19. A power hammer comprising cylindrical members in telescoping relation, the inner of said members being fixed and the outer member movable to provide an expanding and contracting chamber above said fixed member, a hammer piston slidable within said inner member and moved as a result of the variations in said chamber, one of said members having anannular recess in its telescoped portion, and packing material saturated with lubricant filling said recess.

20. A power hammer having concentric members engaging one another with a sliding lit and arranged for relative movement in an' axial direction, certain portions of said members being retained in telescoping relation in all positions of relative movement, the inner member being fixed and the outer member movable thereon to provide an expanding and contracting chamber above said fixed member, a hammer piston slidable Within said inner member and moved as a result of variations in said chamber, said inner member having an annular recess in its exterior Within its continuously telescoped portion, and packing material saturated With lubricant filling said recess. vSigned by me at Cleveland, in the county of Cuyahoga and State of Ohio this 8th day of February, 1928.

A CHARLES B. COATESU

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