US2552840A - Automatically reversible air-driven tapping unit - Google Patents

Description

AUTOMATICALLY REVERSIBLE AIR-DRIVEN TAPPING UNIT D s -f wwmmww wif@ N Aa/.U R EAHB d' 0 VYa. T mim T Nov A T SHC. V. DD @w mw ww. mw Nxmu 3 Sheets-Skaai 2 s. A. BURKE ET A1.

AUTOMATICALLY REVERSIBLE AIR-DRIVEN TAPPING UNIT Filed' Mgy 7, 1948 May 15, 1951 H/woLa HANsEM BY cm. v//vguLL/IRD QMff/r ATTORNEYS.

May 15, 1951 s. A. BURKE ETAL AUTOMATICALLY REVERSIBLE AIR-DRIVEN TAPPING UNIT Filed May 7, 1948 5 Sheets-Sheet 5 INVENTORS STA NLEY/q uR/ff. HAROLD c/-lA/vsf/v, BY CAL V/N/.IBULQ/mo. W744i/ MW r M( TTRNE YS.

Patented May 15, 1951 AUTOMATICALLY REVERSIBLE AIR-DRIV EN TAPPING UNIT Stanley A. Burke and Harold C. Hansen, Westield, and Calvin P. Bullard, East Longmeadow,

Mass.

Application May 7, 1948, Serial No. 25,546

11 Claims. (Cl. 121-34) The invention relates to an air driven mechanical device for driving a tool such as one used for tapping, drilling, reaming or threading. More particularly, it relates to an air driven device which is reversible in rotation in accordance with the work conditions as they develop in the course of an operation.

Objects and advantages of the invention will be set forth in part hereinafter and in part will be obvious hereirom, or may be learned by practice With the invention, the same being realized and attained by means of the instrumentalities and combinations pointed out inthe appended claims.

The invention consists in the novel parts, constructions, arrangements, combinations and improvements herein shown and described.

The accompanying drawings, referred to herein and constituting a part hereof, illustrate one embodiment of the invention, and together with the description, serve to explain the principles of the invention.

Of the drawings:

Fig. 1 is a side elevation of a device embodying the invention and showing attached thereto a conventional tapping tool;`

Fig. 2 is a longitudinal central section through the main body of the device but with certain portions in elevation;

Fig. 3 is a fragmentary horizontal section, somewhat enlarged, taken on the line 3-3 of Fig. 2 but omitting the air driven rotor to more clearly show certain valve arrangements;

Fig. 4 is a transverse section taken along the line 4 4 of Fig. 3;

Fig. 5 is a view similar to Fig. 4 but showing the relation of the parts to each other after their positions have been shifted from those shown in Fig. 4;

Fig. 6 is a longitudinal central section in the same plane as Fig. 2 and showing the rotor housing only Fig. '7 is a transverse section taken along the line 'l-'l of Fig. 6;

Fig. 8 is a transverse section taken along the line 8-8 of Fig. 6;

Fig.` 9 is a transverse section taken along the The present invention has for its object the provision of a novel and improved tool for use in drilling, cutting and otheroperations where a reversible drive is useful, the direction of rotation of the motor depending on whether the cutting means is being moved into or out of the work. A further object is the provision of a motor driven reversible tool in which the direction of rotation of the motor and of the cutting means driven thereby is `automatically controlled by the axial direction of the thrust imposed on the motor or cutting tool. Still another object is the provision of a novel and improved motor driven tool in which power is applied to the motor only so long as normal axial thrust is applied thereto, whereby the motor automatically stops when the cutting tool is disengaged from the work or when the cutting tool is over loaded. A further object of the invention is the provision of such a tool which is extremely rapid in operation, is capable of rapid reversal without the manipulation of any additional control means by the operator, and may be manually moved toward and from the work or mechanically mounted for such movement. The invention further provides a compressed air-powered tool which attains the objects set forth. is compact, may be operated continuously and requires but little service for its continued eiicient operation.

In general, the invention comprises a tool including a motor which is preferably driven by compressed air and drives a rotary cutter, such as a tap, die or drill in either direction of rotation, the direction of rotation being controlled by means, such as, air supply valves, these means or additional means also serving to control the supply of power to the motor so that the motor may be operated or not depending on the conditions. The direction of rotation of the motor is primarily and normally controlled by the thrust imposed on the tool during its operation, although this direction of rotation may be changed at will, if desired, so as to allow the tool to rotate continuously in either direction so long as power is supplied thereto, for instance,

4ounder control of a separate manually controlled air valve. The tool and its power controlling means, such as the valves are preferably constructed so that rotation of the motor is automatically stopped on overloads, such as might occur when a tap has fully threaded a blind hole.

Referring now to the drawings, the main body of the device comprises acylinder I0 which is closed at the rear end by-ra wall Il and at the front end by a threaded plug I 2. Somewhat nearer the rear end, a portion of the periphery of cylinder ID is enlarged into the form of a rectangular block I3 on one face of which maybe secured the handle Lor grip member I4, and in which the various valve ports, to be describedA later, are formed. The bore of cylinder I is provided with a tightly fitted liner I in the bore of which are slidably mounted various operating parts of the device. To prevent rotation of the slidable members and maintain their longitudinal alignment a spline I6 is provided along the entire length of the-bore in4 liner I5 with cooperating keyways provided in each of thesliding members.

The power means for driving the cutting tool attached to the device, as a tap, drill, etc., is a reversible, compressed air motor of the Vvane type and as embodied consists ofa rotor housing I1 which is slidably mounted within the rear half of liner I5 (right in Fig. 2) and held against rotation by spline I6. An eccentric bore zI8' in housing I'I extends from the rear end (right in Fig. 2) of the housing to near the front end where it terminates at an end wall I9. The rear end of eccentric bore I8 is closed by a disc 21)e which.

is slidably mounted within liner I5 but keyed thereto to prevent rotationby spline I6.

. As thusl constructed the cavity formed by end Wall |9,'bore I8 and closure disc 20 provides the space within which the air motor rotor may `be rotatably mounted. The rotor, as embodied, consiste of a'rotor hub 2| secured to a rotor shaft. 22 and is provided with a plurality of radially extending varies 23 which are slidably mounted in equally spaced radial slots along the length of hub 2|. Vanes A23 may be urged outwardly by leaf springs 231 interposed between base of the vanes and the bottom of the vane slots in rotor hub 2|. Rotor hub 2 I, by means of its shaft 22 is. concentrically mounted with respect to rotor housing I1 and therefore is eccentric in relation to housing bore I8 within which the hub rotates. The diameter of hub 2| is such that it has a line contact with the bore I8 along its full length, leaving a crescent shaped chamber between the hub and the bore at all other points. The vanes 23 Yare adapted to project into this crescent shaped chamber and have a sliding Contact at all times with the surface of bore I8 thus dividing the chamber into segments er pockets with increasing and decreasing volume as the hub rotates. Compressed air when admitted into one of these pockets between the varies 23 at a point wherethe pocket -i's of minimum volume expands andby reaction against the forward vane rotates the rotor hub 2| and its shaft vr22 until theforwardvane reaches a'poin't Where the pocket is at its maximum volume when further travel Tof the vane. opens the pocket to appropriate exhaust ports. The rotation thus produced presents successive .pockets tothe compressed air source'and results in continuous. rotation at a. high rate of speed.

f Rotor shaft 22 is rotatably mounted with respect to housing II by means of' a ball bearing 24 carried in a recess in the forwardend of housing I'I and a ball bearing 25 carried in a recess formed in `a ring support 26 which is slidably mounted in the bore of liner I5 adjacent to closure disc 20 but held against rotation by .spline |36. *A .rearwardext'ension of irotor shaft 22 is further journalled in an anti-friction sealingY` bushing Z'I'fixed in a boss 28 formed on -the rear end` of main body cylinder I8. Both ball bearings: 24, 25 are provided with sealing discs 29 on the side towards the rotor hub 2| to prevent the escape of compressedair from the air motor other than by escape ports purposely provided therefore. 1

In ordery to converttherelatively low torque high speed of rotor shaft., 22,-toa`higher torque lower speed tool spindle 30, arranged along the same axis as the rotor shaft, a planetary gear reduction unit is provided therebetween. As embodied a small drive gear 3| is provided on the forward end of rotor shaft 22 and this meshes With two diametrically opposite pinions 32 journalled on pins carried by a rotatable pinion casing 34. The tool spindle v36 "is keyed in a reduced hub portion 35 of pinion casing 34 and secured thereto by means of spindle head 3S and threadedjam nuts 31 carried by the spindle landi-clamping thru the inner race of ball bearing 38.

The non-rotatable 'member of the planetary gear-unit consists-of an internal gear 39 formed on a portion of thebore-4IJ of a sleeve 4|. The pinion casing, 34 is sopositioned within the bore 45 that the pinions 32 mesh with internal gear 36 ofusleeve 41|. Since sleeve 4I is held against rotation by spline I6 of liner I5 any rotation of rotor drive gear 3-I is transmitted at higher torqueand lower speed topinion rcasing 34 and the attached tool spindle .30. The internal gear sleeve 4| Vis .slidably .mounted within liner i5 and held in fixed relation torotor housing Il by having its inner end telescoped over a reduced portion of housing I1 and abutting a housing shoulder 42, and beingiixed at its outer end onY the outer race of ball bearing 38, as well as other means described hereafter.

The forward end of tool spindle 30 passes thru cylinder plug I2 where it 'may bejournaled within an anti-frictionlsealing bush-ing 43 and at its end provided with a removable adapter plug 44 upon which any conventional tool chuck 45 and cutting tool, as tap 46,'may `be secured in driving connection.

Rotational mounting of the tool spindle 30 and attached pinion casing 34' is attained by ball bearing 38 carried in 'the' forward end of internal gear sleeve 4|', and ball'bearing 41 which is xed in a recess in the rearward end ofpinion .casing 34. The inner race of bearing 41 is clamped on the forward end of rotor shaft 22 Vbetween shaft shoulder 48 and spacer 49. .This clamping action is derived from jam: nuts 58 which are threaded on the rearward end of rotor shaft 22 and act thru all the parts directly mounted onthe shaft between shaft-'shoulder 48 and nuts 58.

From the description thus far and an inspection of thedrawings (Fig. 2')- it is clear that allv slides ineither axial direction within `liner I5 but thru apertures 53 and Aa .groove 54 formed in liner I5. a

One vobject. of they device isV to provide a mechanism. whereby thethrustgiven the device by the operator to urge the tool into or out of the work may be utilized to control automatically, by valve means, the rotation in either direction or the non-rotation of the air motor, and hence the cutting tool. As embodied a flexible hose 55 is connected at one end to a source of compressed air (not shown) and at the other to the outer end of the device handle I4. Leading from the latter connection is an air passage 55 which communicates with a shallow cavity 51 formed equally by registering recesses in the handle base 58 and that face of cylinder block portion I3 to which the handle is firmly attached. The cavity 51 functions as a distributor head toltwo sets of inlet ports 6I) and 6I. Inlet ports (i0 are associated with the forward drive action of the cutting tool (counter-clockwise as viewed from the front of the device or as viewed in Figs. 4 and 5) and inlet ports 6I are associated with the reverse drive action as for withdrawing the cutting tool out of the work (clockwise). Inlet ports 60, (forward drive) shown as three in number, lead upwardly from the right side of cavity 5'I (as viewed in Figs. 4 and 5) and through both the block portion I3 and the body liner I5. Ports 60, When properly in register with three valve po-rts 62 formed in rotor housing II permit compressed air to enter the right side of eccentric bore I8 (Fig. 5) and, as previously explained, act upon vanes 23 of rotor 2| to cause rotation of the rotor in a counter-clockwise direction. Inlet ports 6I (reverse drive) lead upwardly from the left side of cavity 57 (Figs. 4 and 5) and thru block portion I3 and liner I5. When inlet ports 6I are in register with three valve ports E3 formed in housing I'I compressed air is admitted to eccentric bore I8 and causes rotor 2| to rotate clockwise. It is to be noted that the two sets of valve ports 62 and 63 in the sldable housing I1 are disposed directly opposite each other on opposite sides of the housing and the three ports in one set are equally spaced from each other. However, in the case of the two sets of inlet ports 6i) and 6|, ports 60 are not opposite ports 6I but nearer the rear (right in Fig. 3) of the device by a distance equal to at least four times the diameter of a port.

the' tapping tool reaching the bottom of a blind hole or an overloading of the mechanism due to a broken tool, etc., the air motor is automatically stopped even before the operator can react to the conditions and bring the motor to a stop manually. As embodied a relatively strong compression ,I valve ports |52.

, to the device by the operator.

spring 68 is nested within the rear spring 52 between ring support 26 and end wall II but it is shorter than spring 52 by a distance equivalent to that necessary to register intake ports 5u and It is adapted to be engaged and compressed by the ring support 26 in the course of the rearward travel of the ring support and resists further relative movement of the operating unit unless additional thrust effort is applied This additional thrust effort occurs when, for any reason, the normal feeding of the tool into the work is arrested by adverse or other conditions and continuing push by the operator occurs. The spring 68 is then compressed and valve ports 62 move stoppage.

Thus when the device body II] is shifted to the left (Figs. 2 and 3) relative to the housing I'I forward drive inlet ports 53 register with valve ports 62 and the rotor 2| rotates counter-clockwise as viewed in Fig. 5 and the expanded air in the rotor pockets is exhausted through three exhaust valve ports 54 in housing Il which are then in register with exhaust ports G5 in liner I5 and body block portion 3. Both the exhaust ports 64 and exhaust valve ports @5 are on the opposite side of the device from inlet ports and 62.

Clockwise (reverse) rotation of the rotor is produced when the main body I0 is shifted to the right (Figs. 2 and 3) relative to housing II until the head of an adjustable screw '10, which is threaded into body plug I2, strikes the forward end of the internal gear sleeve 4I of the slidable operating unit. VThe inlet or reverse ports 6I and valve ports 53 are thus brought into register and, on the opposite side of the device, three exhaust valve ports 65 in housing I'I are registered with three exhaust ports 61 formed in the main body I Il and liner I5 and the air motor is then drivable in reverse direction. Screw 'Ill may be turned to move it to the right (Fig. 2) so as to hold'the slidable unit with the valves G3 in register thereby causing continuous rotation in a clockwise direction.

; Preferably eachof` the exhaust valve `ports 64 Means are also provided in the device to enable it to be run continuously, as for instance in production drilling, still retaining the `overload stopping feature but not the reversing feature. As embodied the adjustable screw l0 threaded into the body plug I2 may Ibe screwed inwardly to force the slidable operating unit rearwardly (against balancing spring 52) until forward inlet ports Bil are in register with valve ports 32. The air motor, in this position, will then run continuously as long as compressed air is supplied thereto or until such conditions arise where the body IIJ moves forward relative to the operating unit (as in overload), compressing spring 5B and shutting off air supply by de-registering intake ports Iii) and valve ports 82 as previously described. V

If desired, when using the device as adjusted for continuous running, a conventional trigger Vtype air valve (not shown) may form part of the handle I4.

The device as a whole is so constructed that it may be used as an attachment for a machine tool as for instance a turret lathe. When used in this manner the side or top faces of body lblock portion I3 may serve as bolting surfaces for brackets or supports (not shown) forming part of the machine tool. Recessed passages 1I, in communication with each of the two sets of exhaust ports 65 and 61 are formed in the two side faces of block portion I3 so that if these sides are usedas bolting surfaces the exhaust air circuit is not blocked.

Operation In a right hand thread tapping operation in a blind hole the device is operated as follows: outer end of tapping tool 46 is placed in the hole entrance and the operator presses the device to wards the work (left in Figs. 1 and 2). The tool 46, `not yet rotating, and the sldable operating in which means are provided for stopping the supply of power to the motor on overloads.

REFERENCES CITED The following references are of record in the le of this patent: lo

10 UNITED STATES PATENTS Number Name Date STANLEY A- BURKE 1,660,201 Lee Feb. 21, 192s HAROLD C- HANSEN- 2,257,892 van Sitten oct. 7, 1941 CALVIN P. BULLARD. 5 2,388,741 Hays 1 Nov. 13, 1945 2,414,638 Dobie Jan. 21, 1947

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