US1191948A - Power-hammer. - Google Patents

Description

c. B. coATIis.

-POWER HAMMER.

APPLICATION FILED Nov. 9, 1914.

Patented July 25, 1916.

2 SHEETS-SHEET l- Z3 I Z6 C. `B. COATES..

POWER HAMMER.

APPLICATION' FILED Novl 9, I9I4.

Patented July 25, 1916. I

2 SHEETS-SHEET 2.

CHARLES B. coATEs, `or ciiIcAs'o, -1`LLINoIs POWER-HAMMER.

referably, though not necessarily, operated y an electric motor as the prime mover and adapted to hammering purposes such as chipping, drilling or riveting by means of a chisel, drill, rivet set, or the like, to one end` of which the striking member of the drill imparts its blow. I Y

The object of my invention is to provide a simple, eflicientand reliable machine of this character, characterized 'more particularly by the employment of a hollow cylinderdirectly reciprocatedl by the electricor other j typeofmotor and containing the hammering piston, the construction and 'arrangement ofthe parts being such as to cause such piston to deliver quick, snappy land powerful blows upon the inner end -of the.v

shank of the workingtool inserted into the front .end of the barrel Within which th hollow cylinder is reciprocated:

Another object of my lnventlon is 'to p'rovide simple and efficient means for blowing out the cuttings, etc., in a holebeing drilled,

such means being adaptedto pump or force air from the front end of the barrel into and through the hollow working tool. I also provide means wherebythis pumping mechanism iscompelled to draw its supply of air direct from the atmosphere and prevent itl from drawing it through'the wo'rking tool which is objectionablel owing to the fact that such air would be charged with the dust and dirt created by the drilling operation.

Other features of advantage and utility in my power hammer will be apparent from the description hereinafter given.

In the drawings Figure l is a central sectional elevationof my power hammer; Figs. 2, 3 and l sections of the barrel and contained' parts showing the hollow 'cylinderl and the piston in its dierent positions; Fig. 5 a longitudinal sectionl of the .working tool shown in the foregoing figures; Fig. 6 a.

sectional v'elevation of a modified form` of construction of barrel showing a .diHerent means for blowing outthe hole and employing the working tool-with a boref'e'xtending Specication of Letters Patent.

" Patented-amy 25, 1916.

Application tiled November, 1914. Serial No. 870,986.

the-flill length; Figs. 7 8, 9 and 10n views similarto Fig. 6 but showing the hollow cyllnder and piston in.their`,diiferent positions occupied during a cycle ofl operation; Fig.

11 aL longitudinal section of the working tool shown in Figs. 6to lO'and Fig. 12 -a section `.on the line 12v-12 of Fig. 6.

My hammer is a power hammer operated preferably directly lby a prime mover located 'in the hammer structure itself and while any suitable motor may be employed as such prime mover, I prefer an electric mo- 'tor because it is thev most convenient;y and compact and' also the most desirable because electric current `which is available everywhere can be supplied thereto at4 any distancewthrough cables. My .invention will therefore be described in connection with an electric motorlocated in the hammer' structure itself as the prime mover withoutdintention orlimitation thereto.

Referring first to the construction illus-` l.trated in Figs. 1 to 5, the machine comprises essentially' the motor structure and its housing or casing at the' upper .or rearwardv end` of the tool and a barrel Yconnected therewith and; containingthe working parts, one of which is operated. directly bythe motor, the barrel also being adapted to receive the v'working tool at its lower or forward end.

Referring to the details of the construction showin-the motor which is here an electric motor of any .desired type is-provided with a casing or housing 1 in which are contained and supported the usual electric motor elements such as the stator 'orifield structure. 2, the rotor or armature 3 and the brushes 4, (as in the case of -a direct current 0r a single phase commutator type.) The armature shaft is journaled' at its ends respectively in the' removable end .head or cap l"11 and the end'head 1b whichv is here shown as-integral with the'casing'l, the armature shaft at this' end projecting through thislatter end head. For the con-v venient handling ofthe tool, a handle 5 is provided in which a'switch is mounted for the control of the 'current to actuate the motor. As shown a rod 16 with a thumb-piece 7 mounted in the grasping portion o f the handle, with its outer end in convenient reach of the thumb or finger of the operator, with the result that the movement of the rod is communicated by -means of a bell .crank 8 to a switch contact 9. When the are of course electrically insulated from the" handle-and the metallic structure of the tool.

Referring to the operating connections between the armature shaft and the hollow cylinder of the'machine or tool hereinafter v specifically described, a counterbalanced center crank 12 is arranged at one side of the motor casing and inclosed by a crank case 13 secured to the motor casing. One of the bearings 14 of the crank is mounted inthe crank case 13 and the other in the end head or plate '1b of the motor casing. In the present instance one of the crank disks I 12av is formed asa gear. which meshes witha pinion 3a secured to or formed on the outer. or exposed end of the armature sha-ft. 1n the present instance this armature pinion is cutdirectly'on the armature shaft itself.

`The -hammer barrel 16'v which may be of suitable dimensions, is adapted to be secured in the lower end of the crank case 13. In the present instance -this barrel is screwythreaded at its upper end in order to .screw into the crank case which is split at its `end and provided with a clampingbolt 17 engaging two similar lugs 13a (one of which is shown in Fig. 1) for the purpose of providing 'a clamp to prevent the barrel from unscrewing.- The/lower end of' the barrel is provided with/.an opening in which by preference isarrangeda bushing y18 to receive the-shank of the chisel or l drin 19.

The crank 12 is provided with a connecting rod or pitman 20 provided lon one'end with a suitable bearing lto lit the crank pin of the crank and on theother end with a v bearing to it'a pin 21 which passes through the parallel lugs 21a on the upper end of a cylinder 22. This cylinderv is hollow, being closed at its upper end preferably by an integral head and closed at its lower end preferably'by a removable head 23 screw-threaded onto the lower end. lof the cylinder body. l Thisl cylinder taken as a whole is reduced in diameter as to its intermediate portionin order to form an annular space 24 between the inner walls of the barrel and the said intermediate `portion of the hollow cylinder.v

In practice and as shown, the upper end'of the cylinder is turned to form a sliding fit in the bore of the barrel. The cylinder head 23 is likewise turned to form a sliding fit in the bore of the barrel so that when it isincorporated with the cylinder body, the cylinder structure has a sliding lit within the" memes barrel by reason of the provision of end ,i

heads thereof as described. The cylinder is provided with two sets of holes 25 and 26 passing throughits walls and communicating between the interior of the cylinder and the annular space 24. I prefer that each `set shall consist of ya series .of holes although one hole if yof proper area or carrying capacity would be suflicient. The two sets of holes are arranged in two parallel planes and at such distance from the ends of the cylinder that the'piston 27 located therewithin shall be enabled to trap the air at the ends of the cylinder and -be compressed thereby as required in the operation of the machine. The piston 27'is a hammering piston, the same being provided with a head which fits the bore of the cylinder 22 and with a stem or extension27a which lits a central bore in the cylinder head 23. lt will be understood that both the head and the stem have sliding fits in the bores in which they travel.

Describing a cycle o-foperation and beginning with the parts in their relative positions shown in Fig. 1 at which time the cylinder 22 is slightly below the uppermosty position and ison its downward stroke, the space 28 behind or above the piston 27 and the space 29 below or in front of such piston are in communication through the holes 25 and 26 and the annular airspace 24 act-l ing as a by-pass between said air spaces 28 and 2 9 so that the air pressure therein is the same. .The cylinder 22 is now being forced downwardly, that is forwardly, by means of the electric motor and the crank and the piston 27 being free in the cylinder lags therebehind in its downward movement owing to its inertia, but when the cylyinder is moved downwardly suiliciently far in relation to the piston 27 so that 'the holesv 25 are cut off by the piston from further com-f munication with the air space 28, the air in such lspace is compressed between the rearward end of the piston andthe upper head of the cylinder. When this compression isy sulicient to overcome the inertia of the piston, the latter then travels in unison with the cylinder, this condition being illus- .trated in Fig. 2. When the crank reaches its lowermost position', the movement of the cylinder momentarily stops and the compressed air in the space 28 drives the piston' downwardly and `'causes its stem 27El to delever a sharp and snappy blow en /the end of the shank of the chisel or drill, as shown in Fig. 3. It isto be noted'that the holes 25 and'26 are now all in communication with the air spaces 24,- 28 and -29v`so that there is no back pressure below the piston head nor any reduction in pressureaboveit tok 'retard the blow.

In Fig. 4 the cylinder is shown as starting upwardly with the piston slightly above hose 34.

vcavity 29 is now being compressed. When the upper endof the stroke of the cylinder is reached the piston is restored to the position shown in Fig. 1 by the expansion of This conpletes a cycle of operation of the machine.

While inl theforegoing description I have referred to the outer or forward end of the tool it.will be understood that this is the proper description when the tool is held inthis 'downward position asy shown in the drawings. However, it is Obvious that the tool is capable of working in any desired position, even 1n an inverted position, inasmuch as the 'action depends'largely on the vinertia of the piston. i

If desired the tool or machine may be provided withl a blowing arrangement for blowing out the dust and cuttings from the hole, the necessary compressed air for this purpose being produced by the machine in itsyoperation. In Fig. 1 I have shown one form of such blowing arrangement and an# other form is shown in Figs. 6 to 12.

Referring to the form illustrated in Fig.- 1, the .lower end of the barrel is provided with an inlet port 30 communicating directly with the atmosphere and governed by a check valve 31. This end of the barrel vis also provided with an outlet port 32 which is governed by an outlet or discharge valve 33. The 'discharge port communicates by means of a suitable flexible pipe or hose with the drill steel 19 which in this particular instance has a central boreor passage 19a which extends from the cutting end lof the t'ool toward the inner or shank end thereof as illustrated in "Fig 5 but not entirely through the tool. The upper end of this passage which isadapted to communicate with the In the present instance I attach the delivery end vof the hose to the drill steel in a removable manner. .and by the means l illustrated in Fig. 5, although other means i Yto which nipple the, hose is attached. The y might be adopted' for thepurpose. As shown a'yielding bushing or collar 35i preferably made of rubber, fits over the drill steel at a point adjacent the port 19" and a bushing or nipple 36 is passed through an opening in one side. ofv such rubber collar,

rubber collar is held i'n place by means of a split ring which is clamped onto the collar by means v of theclamping bolt 3.8,passing through the In Eigsf lugs V39. Y Y y 6 to l12 I have shown a modified has a lateral passage or port 19"- ment ofthe cylinder 22 the stem 'lags behind or strap 37 surrounding the same form of construction as respects` the blowing arrangement, the construction and mode of operation of the hammering elements of the machine being the same as in the vform above described. In this modied form the 'front end of thebarrel is provided'on its 1nter1or with an annular screw-threaded flange 40 into which' the intermediate por.- tion of a bushing 41 screws. The upper end of this bushing 1s provided` with .a marginalv flange 41a provided with a: series of ports 4'1". This lange'tightly fits the inner walls of the barrel and forms an annular space orv chamber 42 between such marginal flange 41a and the annular flange 40. This chamber is provided with a series of inlet ports 43 and the series of ports 41" is governed by a suitable check valve such as the flat ring 44 which is adapted to rise to open the ports 41" on the suction stroke of the cylinder 22 l and to close on the otheror, forward stroke thereof. yThe bushing 41 has a central re-A stricted bore 45whi'ch is of the same diameter as the stem of the piston so that the latter has a sliding fit therein for a-purpose hereinafter explained. In this instance the working tool 46 has a central bore or pas` sage 46"L thatthe space within the bushing 41 communicates with such passage and-is adapted to convey any compressed air therein tothe end of the tool.

Referring "o the Operation ofthe blowing Starting With the position arrangement, and of the parts as shown in Fig. 6, the cylinder 22 is now on its downward or forward movement, with the result that the air in front is forced from the barrel and through the working tool tothe hple'being d illed or the work being done. .The maxima of the compressing movement of the cylinder 22 is substantially shown in Fig. 7 and although the cylinder `22 moves forwardly slightly more than-therein shown the stem `of the piston lmoves rapidly forwardly to deliver its blow and in doing so passes through the port 'or passage 45 in the bushing 41,`thereby closing -thel space in front of the piston from the space in the forwardyend of the bushing. On the return or upward moveiston and its as hereinbe ore explained andv thereby keeps the port 45 closed during substantially the entire period of the upward-movement of the cylinder this time the fresh air from the atmosphere is drawn inwardly'through'the ports 43 and 41" 'and into the forward end of the barrel l'n advance ofthe cylinder 22 and inrear ofkkthe bushing 41. Not until this supply or charge of fresh air is suckedv 1nto the barrel does the stem ofthe piston clear the port 45.. The object and purpose of this construction is to assure the pumping of fresh air and the preventing of any suckwhich extends the entire. length so i s0 that at ing of air mingled with dust upwardly through the working tool with the obvious disadvantages.

l claim:

j 1. In a power hammer, the combination of a barrel, a power operated hollow cyl- `inder slidably fitting therein and having complete circumferential contact with the interior walls of the barrel, said cylinderv having ports in two different points intermediate its length and communicating. with the interior of the cylinder, means a'iording communication between the two ports, said barrel walls being imperio-rate with respect to the external atmosphere where traversed by thecylinder; and-a piston movable in the ing a stem projecting through one end of the cylinder and adapted to deliver its blow upona working tool. I

3. In a power hammer, the combination of a barrel, a power operated hollow cylinder rcciprocable therein and having its intermediate portion reduced in diameter to form mei eee 'an annular air space between it and the `inner walls of the barrel, said barrel walls being imperfora'te where traversed by the l cylinder, and thecylinder having ports in two different points intermediate its length communicating between its interior and said annular space, and a piston movable 1n the cylinder, and having a stem. projecting through one end of the cylinder and adapted to deliver its blow upon a working tool.

4. ln a power hammer, the combination of a barrel, a power operated hollow cylinder reciprocable therein and having-its intermediate portion reduced in diameter to form an annular air space between it and the inner walls of the barrel, said barrel walls being imperforate where traversed by the cylinder, and the cylinder having ports in two different points intermediate its length communicating between its interior and said annular space, and a piston movable .in the cylinder and having a stem projecting through one end ofthe cylinder and adapted to deliver its blow upon a working tool, said ports being arranged at a d-istance from the ends of the `cylinder' to provide air compression spaees for the piston after closing the ports'land such ports together with the annular space forming a by-pass for the yair on opposite sides of the piston when the latter is ina position between the two ports.

CHARLES B. COATES.

llllfitnesses: i I

' LAWRENCE E. MCGAN'N, Jr.,

ROBERT T. DoBBERx/IAN.

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