US1867254A - Pneumatic tool operating apparatus - Google Patents

Description

July 12, 1932. E, CURT| PNEUMATIC TOOL OPERATING APPARATUS Filed Feb. 27, 1928 INVENTOA.` r- Curl/o' E BY 'l 977mb' m ATTORNEYS.

Patented Jul'y 12, 1932 UNITED ERNESTO oUR'rI, or MILAN,Y ITALY PNEUMATIG 'root oPEnATrNG APPARATUS Application led February 27, 1928, Seria1vNo.257,441, and in Italy February 28, 1927.

The invention relates to aerodynamic machines of the kind in which the air pump or better the pneumatic driver supplies compressed air, the amount of which is-limited to the requirements of the machine tool or tools connected theretoby pipings. In the connecting piping of all machines of this kind heretofore known there is a succession of compression and suction phases corresponding to the successioniof the pneumatic phases in the driver,that is Vto say, the air which in the compression phase is forced towards the tool, is afterwards sucked back into the piping. This is a serious inconvenience and a useless, and harmful, recuperation of fluid because, owing tothe fact that itis more diicult to suck a fluid column in a piping than to compress it, the machine tools must be installed relatively near to the driverin order to avoid an excessive length of such pipings; the piping must not exceed a certain limit in length, because beyond such a limit the suction is no longer practicable.

The driving arrangement for pneumaticv 25.' tools according to the invention fullyobviates these inconveniences and essentially distinguishes itself by the fact that in the piping connecting the machine tools to the driver the air is actuated only in the direction from the driver towards the machine tools and this pressure impulse brings about thetools operative stroke, whereas the idle stroke is'operated either by another pneumatic pressure impulse or by a mechanical agent, for instance connecting the two together, D the tool proper.

The driver A, the piston 1- of which may' 50.' be actuated in any convenient manner isy a spring, that comes into action as soon as the'v fitted with a valve 2 through which the outer air is drawn in and with a valve B `through which the compressed airis forced into the connecting piping C; this compressed air cannot return into the pump body, because the valve 8 is closed during the suction phase.`

The air is delivered by the pipingy C into a chamber of the machine tool B, in which a distributor 5 is adapted to slide. The distributor 5 is constantly acted upon by a spring 6 tending to force it towards theair inlet so that the incoming air, with its pressure, forcesthe distributor 5 to the left against the action of the spring.- The various parts are soedesigned that in this backward stroke of the distributor 5 one of the ports 7 provided in the distributor wall registers with i the port 8 opening into the body 9 in which th striking vmass 10 is adapted to reciproca e. ln the hollow distributor 5 a partition 1l is provided by which the distributor chamber is divided in two,`namely one portion receiving the air supplied by the piping C r and the other intended to receive the air f5 that discharges itself from the body 9 through` the opening 12 after having performed work. Beside the ports 7 already mentioned, further ports 13l are provided in the distribu-` tor wall, adapted to communicate, in the manner that will be' described hereinafter, Vwith the chamberl 14 of the machine tool 8, the lower end of the chamber 14- opening `into the chamber 9 for the purpose of bringing the striking mass 10 back vinto its highest 8.5. position. The distributor 5 Yis firmly' provided with yet another set of portsl adapted to set the ldischarge ports 12 into communication with the rear chamber of the distributor and therewith .the outlet to the at- QQ- mosphere, which takes place through the ports 16 of the chamber in which the distributor is slidably mounted. y

Beside the rectilinear reciprocating motion, the distributor' 5 is adapted to perform a revolving motion; it can revolve during the forward motion caused by the spring 6 when the air pressure ceases. In the example shown, the distributor 5 is slipped on aV spindle` 17 solid with a ratchet wheel 18 cooperating with a'ratchet 19. The wheel 18, and-therewith the spindle, can revolve in one direction only, namely when the distributor 5 pushed by the air pressure, moves in backward direction. During this stroke, due to the screw-threading with which the spindle 17 is provided, the distributor 5 and the spindle 17 Vare kinematically coupled up with one another so that, as the spindle can turn, the Adistributor slides without revolving.V On the return stroke on the contrary,due to thev ratchet 19, the screwthreadedspindle 17 is prevented from turning so that the distributor 5, beside its axial movement,`is obliged to revolve through a fraction of a turn so as tobring awport 15 intoregist-er with an outlet port 12, anda port 13 into register with the chamber `14: opening into the chamber 9 below the striking mass 10.

To ensureproper registration of ports 7 with ports 8 or vof ports 13 and 15l with passages 14 and 12 it is suicient to provide the gear wheel 18 with six teeth whenthere are nine Y Y The pawl 19 will snap into the tooth-spacel ports.

of one of the teeth in any case, provided an accurate registration exists between one, of the ports of thev valve and the Corresponding ports 12, or 8 etc. lof the body B.

Even-granting that a certain angular oil'- set may exist due to tlie'friction of the shaft 17 in its bearings, yet since the pawl 19 cannot possibly stop half-way of the tooth-flank butV must necessarily engage one tooth or the 35v other the corresponding ports will always register with one another.

This fact Vhas been positively ascertained in actual Apractice because the springfthat for urges th'epawl 19 acts upon this-pawl and therewith also on the gear wheel 18 in such amanner Vas to correctthe eventual olf-set caused by friction.

After the above description, the working of the arrangement will readily be under-V stood.

Let the piston 1 be moved upwardly; the suction valve 2 will close and the delivery valve 3 will open. The compression impulse will transmitY itself through piping C vand reach the forward chamber of the distributor; forcing the latter to the left asV shown in Fig. 1 and when insuch extreme position all ports 13 are closed while one of the ports 7 communicates with the port 8 so that the impulse will simultaneously with the initial a consequence, the compressed air delivered by the piping C will impinge against the underface of the striking mass 10 and force it upwardly into its rest position, and thusv oblige the air enclosed in 'the chamber9 to escape tothe atmosphere through 12-15-16L Y It will readily be understood that in the successive compression phases of the piston 1 the compressedair will find opena port 8 and so on. f

Since in order-to raise the striking mass 10 a small air pressure is suflicient, the Vwall of the body in which the striking-mass is reciprocating is provided with openings 21 through whichthe compressed air can freely escape.

As regards the cross-sectional area of the` ports 21, it is to be noted that in order to raise the piston 10, a relatively small pressure is sufficient, because theupward stroke of the piston-.is not an operative stroke. Accordingly, the pressure that remains in the chamber underlying thepiston v1() (difference between the pressure ofthe fluid entering through 14: and the pressure Vof the fluid` fluid to discharge itself to atmosphere; Fork thisreason, even if in the chamber underlying the piston a certain pressure is left in excess of atmospheric pressure, it is readily overcome by the pressurey exerted in downward direction on the operative stroke.

The modied construction according to Fig. 2 differs from the foregoing one in that the striking mass 10 is brought lback into its normal posit-ion',ready for receiving .the impulse, by a spring 22 insteadrof by pneumatic action.V Of course the adoption vof this mechanical means involves some'modifications also in the distributor 5" inasmuch as Vits revolving movement is novlonger required. In

this case the distributor comprises an inletY chamber 23'and an outlet chamber 24 and is placed under the action of a spring v6 tending to move the distributorin opposite direction to that of the air impulse. When an air impulse takes place, the distributor moves backwardly and causes the inlet chamber*L 23 to communicate with the inlet` opening 8 the striking Ymass 10v being ythus sharplyY forced downwardly and the spring 6 compressed. As soon as the compression action of the piston 1 ceases, the striking mass 10 rises and causes the -air to discharge itself through the outlet opening 12 which is now in communication with the outlet chamber 24 of the distributor 5. The initial conditions are thus restored and the described cycle repeats itself over again.

From the abovesaid it will be apparent that in the connecting piping C, C, rather than a travelling motion in the direction from the driver or pulsator towards the machine tool, there takes place a series of extremely quick compression impulses that transmit themselves to the distributor and to the .striking mass. In order that the antagonistic spring 6, 6 may readily exercise its action as soon as the compression impulse ceases, the vent or narrow bleed opening 6 is provided, this opening setting the inside of the connecting piping into communication with the atmosphere and allowing the discharge of the over-pressure that remains in said piping.

In a general way, the details may be varied as will be found convenient without departing from the spirit and scope of the invention.

What I claim is 1. In combination a pneumatic driver including a piston and a valve controlled compressed air supply pipe, a machine tool connected to the supply pipe and including a piston, and a rotatably mounted distributor also movable in one direction in the tool in response to each pressure applying impulse of the driver piston and provided with ports certain of which control the admission of compressed air to the piston in the tool so that the latter is given its operative stroke simultaneously with the pressure applying impulse of the driver piston, the remaining ports of the distributor acting to control the application of asecond impulse on a tool piston for returning the latter to its original position during the rotation of said distributor.

2. An arrangement as claimed in claim 1, wherein spring means is provided for acting on the distributor in a direction opposite the pressure applying impulse of the compressed air.

3. An arrangement as claimed in claim 1, wherein the tool is provided with a chamber having ports communicating with the respective ends of the piston, and the distributor being mounted in the chamber so that its ports may be successively and alternately brought into registration with the ports in the chamber which communicate with the piston, substantially as and for the purposes set forth.

4. In combination a pneumatic driver including a piston and a valve controlled compressed air supply pipe, a machine tool connected tothe supply pipe including a casing providing a cylinder having a chamber adjacent one end of the cylinder and also provided with ports establishing communiv cation with the respective ends of the cylinder, a piston in the cylinder, a distributor mounted to reciprocate and partially turn in said chamber and provided with ports which are adapted to register at times with the ports leading to the respective ends of the cylinder, said distributor being movable in one direction in response to each pressure applying impulse of the driver piston to alternately move the tool piston in opposite directions, and spring means acting on the distributor in a direction opposite the pressure applying impulses.

5. An arrangement as claimed in claim 1, wherein the distributor includes a stem hav ing a spiral thread, a body having the ports therein mounted on the thread on the stem, and pawl and ratchet mechanism for permitting rotation of the stem in only one direction, substantially as and for the purposes set forth. Y

ERNESTO" CRTI.

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