US2231864A - Attachment for drilling machines - Google Patents

Description

Feb. 18, 1941. s ABEL 2,231,864

ATTACHMENT FOR DRILLING MACHINES Filed Aug. 25, 1938 2 Sheets-Sheet 1 Feb. 18, 1941. F. s. ABEL ATTACHMENT FOR DRILLING MACHINES Filed Aug. 23, 1938 2 Sheets-Sheet 2 ll unH H 3 FRA/VfiS-ABEL WWW Patented Feb. 1941 PATENT OFFICE ATTACHMENT FOR DRILLING MACHINES Frank S. Abel, La Grange, 111., assignor of thirty-- three and one-third per cent to Cora B. Korrer,

Fond du Lac, Wis.

Application August 23,

6 Claims.

breaking of drills during-.tlf'progress of the drilling operation.

There are two general causes of drill breakage during drilling. One of these is the application of excess pressure to the drill in a direction axial thereof. The other is the catching of the drill when it enters the work or when it cuts through the side opposite to the side that it enters. The first named cause is related to the resistance of the drill to longitudinal bending. Excess pressure will cause a drill, especially a long and relatively thin drill, to bend between the chuck and the work. This bending may cause the drill to work oil from the line of intended drilling resulting in improper drilling, and the rotation of a drill in a hole that is not true almost invariably results in breaking the drill. The bending may also strain the drill beyond its elastic limit and the drill will be permanently bent and useless.

The second cause is related to the torsional strength of the drill. When the drill point first begins to cut into the work, or when it cuts through the work, it tends to stick and catch and the body of the drill is subjected to a twisting strain between the chuck and the point of catching. This strain, especially in long drills, is very apt to exceed the strength of the drill, and many drills are broken by the twisting strain that is imposed when the point sticks. In this connection it may be pointed out that. a short body has much greater torsional strength than a longer body of the same diameter.

One object of the present invention is the provision of a novel attachment for drilling machines that will transmit both the thrust and the rotative force of the chuck to the drill at a point closely adjacent the surface of the work.

Another object is the provision of such an attachment that has novel means for supporting a drill against bending throughout a major portion of its length adjacent and above the point at which the drill enters the work.

Still another object is the provision of an auxiliary connection between a chuck and a drill mounted therein that will permit feed of the drill 1938, Serial No. 226,379

turn mechanism that will, when the feed pressure of the machine is released, withdraw the drill from the work, and return the assembly to its starting position ready for the next operation.

In the accompanying drawings: Figure 1 is an elevation of the attachment mounted on the chuck of a machine. Figure 2 is a sectional elevation. Figure 3 is'a sectional view on line 3-3 of Figure 2. Figure 4 is a sectional view on line 4-4 of Figure 2.

Figure 5 is a sectional view online 55 ofFig ure 2.

Figure 6 is a sectional view onure 2.

Figure 7 is a broken elevation of the cylindrical body member of the device.

Figure 8 is a fragmentary elevation of the member that controls the depth gauge.

Figure 9 is an enlarged fragmentary elevation of the hollow drill-supporting and driving shaft. Figure 10 is a sectional view on line l0--lll of Figure 9.

Figure 11 is a sectional view on line ll-ll of Figure 9.

Figure 12 is a sectional view on line l2-l2 of Figure 10.

Figure 13 is a perspective view of the member that is used to connect the drill to the hollow driving and supporting shaft.

Describing the drawings more particularly, in Figures 1 and 2 a machine chuck is illustrated at l5, such chuck being illustrated as a well known standard type, but which may be, of any other construction. Suitably secured to the chuck l5 for rotation therewith is a cylindrical casing or body member l6 thatcomprises an annular side wall I! that extends between a rim l8 engaged with the chuck and a head I9 that closes the outer or forward end of the casing. The rim l8 and the head It are slightly larger in diameter than the wall l1, and they formshoulders 20 at each end of the wall. Between the shoulders '20, the wall is provided with an axially extendingslot 2|.

The head I9 has. a. central ,bore 22 that is in line with the center of the chuck l5, for slidably receiving a hollow drill-supporting and drivingshaft 23 that extends from a point within the casing l6, through thebore 22, and outward to a point beyond the end of the head IS. The outer surface of theshaft 23 is fluted, theflutes 24 corresponding in pitch to the flutes of the drills line 6-6 of Figused with the attachment, and the head l3 bears lugs that extend into thebore 22 and engage in the flutes of theshaft 23.

At its outer end, theshaft 23 has a threadedcounterbore 25 in which is mounted a disk-like member 21 that connects theshaft 23 with a drill D mounted in the chuck I I5 and extending through the casing l6 andshaft 23. Themember 21 is preferably made of a hard, fibrous material that will not damage a drill but that is suillciently rigid to key together theshaft 23 and a drill extending through it. Rawhide is a material excellently suited for this purpose. Afelt washer 28 is placed in the assembly with themember 21. Themember 21 has acentral opening 23, as has thewasher 28, for the reception of the body of a drill, andtongues 30, that correspond in size and shape to the configuration of the drill flutes, extend into the opening for engagement in the flutes.

The connectingmember 21 is rigidly secured with relation to theshaft 23 by ajam plug 3| that is threaded into thecounterbore 23 and presses themember 21 and washer 23 tightly against the inner end of the bore. Advantageously, the plug has anangular flange 32 for engagement by a wrench, and the plug is provided with astud 33 that extends beyond the end of theshaft 23 for supporting a thrust member. Theplug member 3| is bored from end to end to provide passage for a drill extending from the end of theshaft 23.

The thrust member supported upon thestud 33 consists of aball rest 34, bored to receive a drill, and faced off at one side to provide chip clearance. The ball rest is surmounted by acup 35, the wall of which surrounds thestud 33 to which it is rotatably secured, as by the screw andchannel connection 36.Ball bearings 31 may be inserted between the end of thestud 33 and thecup 35.

From the above, it will be seen that theshaft 23, by reason of the engagement of thelugs 25 in itsflutes 24, will be rotated with the casing I3 and chuck l5, and that a drill D extending from the chuck through the assembly to theball rest 34 will be locked for rotation with theshaft 23 by reason of the engagement of the tongues of themember 21 and washer 23 in its flutes. Because theflutes 24 of theshaft 23 correspond in pitch to the flutes of the drill, theshaft 23 may movie axially of the assembly by performing a spiral motion with relation to both the head l3 of the casing and the drill, and as the drilling progresses and the chuck, casing and drill advance, theshaft 23, being held against advance by thestationary ball rest 34 that rests upon the surface of the work, will be turned by the lug and flute connections, resulting in relative spiral motion between it and the other parts, and theshaft 23 will be progressively received into the casing It.

The effect of this construction and arrangement is to rigidly key together the drill at the point where it enters the work, and the chuck, so that the drill is not driven only through its direct connection with it at a point remote from the work, but is also driven at a point close to the work through the casing I3,shaft 23 and mem--ber 21. This auxiliary drive relieves the body of the drill of the twisting strain throughout the greater portion of its length, and subjects only that portion of the drill that is between themember 21 and the point to such strain. As mentioned above, a short body is much more resistant to twisting strains than a long body, and

the auxiliary driving of the forward portion of the drill results in avoiding a great deal of breakage due to the sticking of the drill in the work.

The pressure exerted by the chuck along the axis of the drill is similarly transmitted from the chuck through the casing andshaft 23, and is delivered to the drill by themember 21, and therefore the drill is relieved of such pressure between the chuck and themember 21 between which it is rigidly held. Inasmuch as the drill is adequately supported below themember 21 by theball rest 34 and the bore in the work, there is little danger of the drill being flexed even by a heavy pressure. In addition to bridging the thrust from the chuck to the drill at a point near the work, the drill is supported against bending through a great portion of its length by theshaft 23 and theball rest 34.

To lubricate the cutting edges of the drill and the moving parts, anoil hole 42 leading into the interior of theshaft 23 is provided. Oil may be introduced through this hole into the flutes of the drill within theshaft 23, and as the drilling progresses the oil seeps past themember 21 and to the drill point, its passage being controlled by the feltwasher 23 which is constructed to closely conform to the cross section of the drill to act as a wiper as the drill moves spirally through it. By this means, adequate lubrication, is p ovided, not only for the cutting action of the drill, but also for the meeting surfaces of the drill andshaft 23 and ball rest 34 respectively.

The following mechanism provides an automatic and easily adjustable depth gauge, and also a means for automatically raising the drill out of the work when the feed pressure of the machine is released. I

Adjacent its inner end, and within the cylindrical casing IS, theshaft 23 carries acollar 38 that rotates with the shaft, and acoil spring 39 is interposed between thecollar 33 and anannular shoulder 40 formed by the inner periphery of the rim l3 at the upper end of the wall H. Thespring 33 is of sufficient strength to exert a force great enough to raise the drill, assembly, and chuck by thrusting against therim 40 andcollar 33, the thrust being exerted through theshaft 23 and ball rest 34 upon the surface of the work. An antifriction device such as theball race 4| may be interposed between thecollar 38 and the end of thespring 39.

Below thecollar 33 and spaced therefrom is a collar 43 that is mounted upon and rotates with theshaft 23. Anonrotary collar 44 rests upon the collar 43 and carries apin 45 that extends radially from the periphery of the collar through theslot 2| in the wall H of the cylindrical casing to a point beyond the outersurface of such wall.

Anannular member 46 is rotatably mounted between theshoulders 20 of the casing l6 and surrounding the wall I1, and said annular member has an axially extending slot 41 that is somewhatwider than theslot 2| with which it is adapted to register. Rack teeth 48 are arranged along one side of the slot 41 for thepin 45 to engage, whereby the position of theshaft 23 with axial relation to the casing |6 may be fixed.

The edge of the slot 41, upon the same side as are the teeth 43, and adjacent its upper end is extended upwardly and at an angle across the slot to form an inclined cam surface 43. Adjacent the foot of the slot 41, the opposite edge is extended downwardly at an angle to form a second oppositely extending inclined cam surface 50. The upper cam surface 43 forms a means of tripwhich theteeth 44 engage the pin. a tongue 52' depends from its lower edgeand extends into apocket 53 in the underlying upper surface of the head IS. Aspring 54 .within thepocket 53 bears upon the side of thetongue 52 to urge it toward the end of the pocket. I

Astop sleeve 55 is rotatably mounted about the upper portion of theannular member 46 and this sleeve is provided with a dependingarcuate fin 56 extending over and along the surface of themember 46 to a point overlying the surface of the head IS. Thefin 56 has an edge 560. that is inclined to the axis of the assembly and to theslots 2| and 41 across which it is adapted to be moved as the-sleeve 55 is turned, thereby providing an adjustable stop for limiting the travel of thepin 45 along theslots 2| and 41.

A series of holes 51- is provided in the surface of theannular member 46 to receive alocking stud 58 extending inwardly from the inner surface of thefin 56 to positively lock the fin in its adjusted position upon themember 46. Thefin 56 is sufliciently resilient to permit it to be sprun outwardly to disengage thestud 58 from the respective holes 51, so that the fin may be adjusted.

A series ofpockets 59 is provided in the outer surface of the head I!) in the path ofspring lug 60 extending from the edge of thefin 56, so that the fin may be releasably and temporarily secured in adjusted position with relation tolthe head I9. Thepockets 59 and thelug 60 are so formed that the lug, when engaged in a pocket, will ride out of it quite easily when a turning force is applied between the head and the fin.

To adjust the device, thefin 56 is turned upon themember 46 until itsedge 56a crosses the slot 47 at the proper point to stop travel of thepin 45 when the desired depth of drilling has been reached. The fin is rigidly secured to the annular automatic return is to be used, without gauging the depth for less than the full travel of the drill that the assembly permits, thecollar 55 is turned so that theedge 56a of thefin 56 is clear of the slot 41, this adjustment of parts being shown in Figure 1. At the start of the drilling, theshaft 23 will be in its most extended position and thecollars 4|, 42, 43 within the casing will be at their outer limits of travel, thepin 45 also being at its outermost position. As the drilling progresses, the chuck and'the casing assembly, will approach the work as the drill advances, and theshaft 23 will be progressively received into the casing I6. This movement results in therelative upward travel of thepin 45 along theslots 2| and 41. When thepin 45 reaches theupper cam surface 49, its further travel'moves the member 46 (to the right as seen in Figure 1). This turning of themember 46 places the lower oppositely inclined cam surface in across theslot 2|. The upward motion of thepin 45 continues until it comes into contact with the end of the slot 41 at 6|, when further relative motion between thepin 45 andmember 46 is prevented,this stopping the feed of the drill into the work since the thrust of the chuck is then transmitted through themember 46,pin 45, andshaft 23 to the ball rest 34 that rests upon the surface of the work. When the feed pressure of the machine is released, the thrust of thespring 39, exerted between theshaft 23 and the upper end of the casing l6, will raise the casing l6, withdrawing the drill from the work. As the casing ismoved upwardly, there will be relative downward motion by thepin 45 since it is supported upon theshaft 23 which is being thrust out of the casing. When the pin comes into contact with thelower cam surface 56. themember 46 is turned vback to the position it occupied at the start of the operation, and the assembly is then in condition for another drilling operation.

When the depth of the drilling is to be limited to a distance less than the full travel that the assembly will permit, thecollar 55 is rotated upon themember 46 until thepointer 64 indicates the required depth upon thescale 62. This adjustment will place theinclined edge 56a of thefin 56 across the slots "and 2| at the point that is proper to stop the relative movement of thepin 45 in the slots when the drill has been projected the required distance. locked in adjusted position with relation to themember 46 by the engagement of thestud 58 in a. hole 51, and releasably held with relation to the head I 9 by the spring lug in engaging in apocket 59,-and the edge 51 being inclined in the manner of theupper cam surface 49, when thepin 45 strikes theedge 56a, thefin 56, and with it themember 46, will be turned in exactly the same manner as above described in full length drilling by thecam surface 49. This turning places the lower cam surface across the slots, asln full length drilling, so that upon return of the pin, the assembly will be placed in starting position. After the pin has turned themember 46, its travel is stopped by theedge 56a, and thereafter the release of the feed pressure of the machine will enable thespring 39 to operate to withdraw the drill from the work, the withdrawal also operating to return the pin to the lower end of the slot where it will engage cam surface 50 and turn the assembly back to starting position.

In either full length or gauged depth drilling, if a drill too short to extend beyond the ball rest 34 is used, or if it is desirable for any reason to extend the drill beyond the ball rest before drilling is begun, thepin 45 is seated upon one of the teeth 48, the tooth being selected to adjust the extension of theshaft 23 from the casing to the required relation to the length of the drill. Upon starting the drill, the pin, during its relative upward motion, will engage the bottom of the next higher tooth which it will move aside, and themember 46 andfin 56 will be thereby turned, lacing theupper cam surface 59 across the slot 2 I. The upward relative motion of thepin 45 in theslots 2| and 41 will then continue until the pin strikes the cam surface (in full length drilling) or the edge 56:: of the fin (in gauged depth drilling), which will turn the fin and annular The fin being securely 35 member and then stop further progress of the drill'as above described. Upon release of the feed pressure, the drill will be raised, the pin moving downward with relation to themember 4! un- Q' til it reaches the bottom of the slots, when the raising of the drill will be stopped, and from where the pin may be raised to again be seated upon the proper tooth 48 for another operation.

In each of these operations, the turning motion of the fin upon the head It is permitted by thespring lug 60 snapping into and out of the pockets at as it moves over the surface of the head. Themember 46 and thenn 5!, however, are securely held together by the stud I and holes 51 until the adjustment is manually changed.

It will be understood that although the attachment is illustrated and described as being mounted upon a geared chuck, it may be used with any other type of chuck, for example, the Morse taper chuck, or any other sort of rotary power head that is suitable for drilling, by providing it with a suitable means for engaging th chuck ,or head.

The attachment that has been described will effectively protect drills from breakage due either to excess feed pressure or to twisting strains that are developed when the drill catches in the work. It is especially useful with the modern high speed drills that are extremely hard and heat resistant, but which are relatively brittle. The use of such drills is of great advantage, since they are capable of being driven at high speeds and rapid cutting, resulting in great savings of time, but such drills are expensive, and unless they are protected against strains developedin drilling, they are subject to a high breakage rate, which, when combined with their cost, detracts from their desirability. The use of this attachment reduces the breakage rate materially and therefore cuts From the foregoing it is thought that the construction, operation and many advantages of the herein described invention will be apparent to those skilled in the art without further description, and it will be understoodthat changes in the size, shape, proportions and minor details may be resorted to without sacrificing any of the advantages and without departing from the spirit of the invention as set forth in the accompanying claims.

What I claim is: Y

1. A safety attachment for drills comprising a casing for mounting on the chuck of a machine for rotation therewith, a hollow shaft slidably mounted in the casing and adapted to surround a drill mounted in a chuck upon which the casing is mounted, a key device carried by the casing and engaging the hollow shaft for driving said shaft with the casing, and means mounted adjacent the end of the hollow shaft for engaging a drill extending through the shaft and driving it with the shaft, said means permitting axial motion between the shaft and a drill so engaged and driven by it.

2. A safety attachment for drills according to claim 1 wherein the casing has a forward head provided with a bore through which the hollow shaft extends, the outer surface of the shaft is provided with flutes corresponding in pitch to the flutes of drills to be used with the attachment, and the head of the casing is provided with lugs that engage in the flutes of the shaft, and themeans mounted adjacent the end of the shaft for enga ing the drill comprise tongues that engage in the flutes of such drill.

3. A safety attachment for drills according to claim 1 wherein themall of the casing has an axially arranged slot, a pin is mounted upon the shaft within the casing and extends outward through the slot, and a movable stop is mounted upon the casing for adiustably limiting the movement of the pin along the slot and thereby limiting relative movement between the shaft and the casing.

4. A safety device for drills comprising a hollow cylindrical casing for mounting on the chuck of a machine, said casing having a side wall provided with an axially arranged slot and a forward head having a central bore, a fluted hollow shaft extending from a point beyond the head of the casing through the bore and into the interior of the casing, lugs carried by the head within the bore and engaged in the flutes of the hollow shaft, a spring mounted within the casing and engaged with the casing and the shaft for uiging the latter outwardly, means rigidly carried by the shaft adjacent its outer end for engaging the'fl'utes of a drill extending through the shaft, a bearing member rotatably mounted on the end of the shaft for engaging the work, a radially disposed pin rotatably mounted on the shaftwithin the casing and extending through the slot in the wall thereof to-a point beyond the outer surface of the wall, an annular member surrounding the cylindrical casing and rotatable thereon, said wall having a slot for registration with the slot in the wall of the casing and one side of the slot being provided with a pluralityof teeth for engaging the pin mounted on the shaft, a stop sleeve mounted about the surface of the annular member and having an inclined surface movable across theslots as the sleeve is rotated for limiting the movement of the pin along the slots, and means for securing the sleeve in adjusted position.

5. A safety attachment for drills according to claim 1 wherein the wall of the casing has an axially arranged slot, a pin is mounted upon the shaft within the casing and extends outwardly through the slot, an annular member is rotatably mounted about the casing and is provided with a slot for registering with the slot in the casing, and the ends of the slot are provided with oppositely inclined cam surfaces for engagement by the pin to turn the member as the pin approaches the respective endsof the slot.

6. A safety attachment for drills according toclaim 4 wherein the annular member, at the respective ends of the slot is provided with oppositely inclined cam surfaces extending across the slot for engagement by the pin as it approaches the respective ends of the slot, and the annular member is'adjustably keyed to theadjustable FRANK s. ABEL.-

' stop sleeve.

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