US2950636A - Safety drivers for gun drills - Google Patents

Description

Aug 30, 1960 E. D. oPPENHElMER SAFETY DRIVERS FOR GUN DRILLS Filed July 13, 1956 m uw um f Q s .\J l.- H .l HUF HNHNNNIHMMH wulllh huw MMO/M m mw Q [Ln w, n@ mm WN mw n ml MN %N M am ww Q ,w M w QQ A @A E \|4 Q I IIUHHI ||||l| I |l|| IIIHIIMNWIII It l MW. mw uw @Q w ,f QQ mf L 'U S @n .Nulml mm NQ Q WQ@ SQQNN wm m @NQ 5m, QQ SUT NQ W N b Q Q s Q @www QQ Q RN NN K R S .k n A. *LIM United States Patent O fiice SAFETY DRIVERS Fon GUN DRlLLs Edgar D. Oppenheimer, Milford, Conn., assignor to Eldorado Tool & Mfg. Corp., Milford, Conn., a corporation of 'Connecticut Filed July 13, 1956, Ser. No. 597,635

8 Claims. (Cl. 77--29) The present invention relates to driving devices, and it particularly relates to driving devices for a type of boring or drilling mechanism known as a gun drill.

The present invention will be particularly directed to gun drills in which the relatively fragile drill or boring device is rotated, whereas the work consisting of a piece of metal is held fixed. But it is understood that the present invention has a particular application to vertical and horizontal drilling or boring mechanisms, and it has quite wide application outside of this specific application.

The present invention will be particularly directed to the manner in which the fragile drill device is mounted and held during the drilling operation and the manner in which the base of the drill is carried by the spindle.

ln connection with gun drills, the work piece is frequently finished before the drilling operation and represents a considerable expenditure of labor, and it is important that the drilling operation take place with as high a rate as possible of finished perfect pieces which will pass inspection, without any substantial number of broken drills or damaged work pieces, and without any likelihood that the work will be operated on by a damaged drilling member during part or all of the drilling operation. t

Another object of the present invention is to provide a safety system which may provide automatic warning or automatic shut-od of the machine, which will give assurance of a higher percentage of perfect finished work pieces and a negligible number of damaged work pieces resulting from imperfections or breaking of the drills or other dificulties during the drilling operation.

Another object is to eliminate or decrease the possibility of breakage of the gun drill in the work due to operator or machine failure or resulting from undue wear or chipping of the cutting edge, all without substantially increasing the amount of labor involved or Vthe expense of the drilling operation.

A particular object of the present invention is to provide a safety arrangement for gun drills of the character described in which there will be maximum protection of the drill from both excessive torque and excessive thrust, and in which, in case of development of either excessive torque or excessive thrust, should either be provided -a signal or an automatic control should be actuated to stop the machine.

A further object of the present invention is to provide a safety device for gun drills of the character described, in which, in spite of the fact that the gun drill is rotated at a relatively high speed with liquid coolant being transmitted to the drill throughout the operation, such safety device will be operated in the presence of the coolant and not be aiected by the high speed operation.

Still further objects and advantages will appear in the more detailed description set forth below, it being understood, however, that this more detailed description is not given by way of limitation, since various changes therein may be made by those skilled in the art Without departing from the scope and spirit of the present invention.

In accomplishing the above objects, it has been Jfound 2,950,636 Patented Aug. 30, 1960 vide a friction drive as between the holder and the carrier for the drill.

In one preferred form of the invention, the rotating spindle nose adapter is provided with a two-step plug oarn'er or driver, to which or upon which the drill shank is connected.

In the preferred form of the invention, the friction drive or contact and the torque is achieved by a wedging Contact or a contact over a Hat or conical surface which will give the full necessary torque at the tip of the drill without consuming an excessive portion of the thrust exerted hydrostatically on the driver.

In la preferred construction, a friction plate is provided which is desirably formed of hardened steel, which serves as friction contact member and which is clamped in position by a threaded cap on the rotating spindle nose adapter.

A small clearance is provided in the chuck so that part of the coolant will always flush through the chuck arrangement and prevent any entry of chips or dirt into the chuck arrangement, whereas the major portion, or substantially all of the liquid coolant, will pass through the drill and then be returned through a groove or the exterior to the drill to the. end of the work piece, where it is discharged. If desired, small sub-drivers or small sub-adapters may be provided to enable ready changing of 4drills Without changing the safety drivers or without opening the driver assemblies.

Where it is not possible to secure constant manual supervision of the machine, which would enable the operator to stop the machine upon excessive load on the drill, a variety of simple mechanical, optical, electrical or audio safety arrangements may be provided.

In one preferred form of the invention a bell crank lever may operate in annular groove adjacent the safety driver and will be connected to actuate a limit switch.

=In another arrangement, a push rod may extend entirely through the spindle and may be connected to operate a switch at the pulley end of the spindle. Both devices may operate a warning buzzer, or shut 0E the machine automatically.

With the Iforegoing and other objects in view, the invention consists of the novel construction, combination and arrangement of parts as hereinafter more specifically described, and illustrated in the accompanying drawings, wherein is shown an embodiment of the invention, but it is to be understood that changes, variations and modifications can be resorted to which fall within the scope of the claims hereunto appended.

In the drawings wherein like reference characters denote corresponding parts throughout the several views:

Fig. l is a longitudinal sectional view of one embodiment of the present invention, showing the spindle, spindle housing, together with the safety driver and base portion of the drill.

Fig. 2 is an enlarged showing of the safety driver illustrated in small scale at the right of Fig. l.

Fig. 3 is a side elevational View, partly in section, ofthe drill base and plug, removed from the safety driver assembly, slightly modied to show a sub-driver arrangement.

Fig. 4 is a side elevational view of the safety driver assembly of Fig. l modified to provide an alternative safety indicator arrangement.

Referring to Figs. l and 2, there are shown a spindle housing A, a spindle B, and an interior through push rod C for operating the limit switch arrangement D.

Thespindle'B is driven by the pulley E, and it in turn drives the safety driver arrangement F to which the present Adriver adapter G, which in turn receives in arecess the hardened inserti-I.. e Y .-The 'nsert ineturnV has a ,recess receiving the spindle driver plug I which has the rearwardlyextending, reduced .end portion K Vand the forwardly extending portion'L which carries the gun drill M. The plug I is hydrostati- .cally forced against the hardened friction plate N, which is held in positionby the internally threaded cap l. i Referring specifically to Fig. l, the spindle housing A carries the ball bearing rings and 11, ywhich permit rotation of the spindle B, upon which is mounted the pulley E at itsleft end. j -The spindle B is boredV longitudinally at 12 to receive Ythe shaft'or pusher rod C. VThis rod is a safety device which will be described more fully.

` The pulley E is press-fitted, 'or otherwise held upon the reduced diameter portion 13 of the spindle B by means of the threaded cap 14.- The spindle B is in turn clamped to the inner race of the ball bearing 10 by the nut 15.V

At the other side, the shoulder 16 will be held against the inner race ofthe ball bearing 11. spindle has a flange-17 to which is attached the plate 18 of the spindle nose adapter G by the bolts 19.

The adapter Gf` is shouldered at 20 to receive the sleeve 21 which has an inlet connection 22 for the coolant supply 23. This coolant may consist of a lubricant or cooling oil or other specially designed liquid.

The coolant may also be introduced through the hollow spindle B from the rear of the machine, in which case the `radial feed 23 may bey omitted.

The liquid will flow into the peripheral groove 24 in the spindle nose adapter G and then ow through the radial passageways 25 into the central recess 26. The

adapter, as shown best in Fig. 2, has a central recess 27 in which is litted the hard insert 28 held in position by Vmeans of the set screw 29 fitting in the groove or at 30 (see Fig. 2). f

The insert 28 has a longitudinal passage 45, which communicates with the through passage 26 to receive vthe coolant. i The rearwardly extendingrmember K will closely fit in the passage with small clearance 46. The pressure of the coolant will be exerted upon the face 47 as well as on the shoulder 47a near the end of the reduced diameter portion 48. Y

thedrill M andreturn through the flute of such drill Q, bringing back any chips or waste material which may be discharged adjacent the adapter.

. 4 grooves 51 may be replaced by bores spaced Well inside of the outer periphery of the plug J.

In the preferred form, the plug I has a main cylindrical section 55 which has a reduced diameter section 56 with e. beveled forward section 57 having the friction beveled face or frusto-conical gripping face 58. Less preferably, a at transverse contact face may be employed in lieu of the conical face.v

This 'contact face 458 acts upon'thre conical face 59 oftheA friction plate N.

The friction plate N has an annular nose 60 lwhich ts into the periphery `of the recess 61, and also has a flange 62 which is'clamped between the face 63 and the hase 64 of the cap P.

'Ihe cap P has the openings 65 to receive a wrench to tighten it upon the thread 66 and clamp the hardened friction plate in position. The angle of` the driving contact 58--59 will afcorresponding Y Afect the amount Vof drivngtorque available, andthe ma- The end of the f YThe coolant Will flow through the central bore 49 into The leakage through the clearance 46 will permit flow of'oil'orcoolant into the recess or chamber 50 which receives the plugJ.V

Any leakage from the chamber 50 will pass through the grooves-51 in the plugl and through the space or annular passage 52 and then to the exterior, as indicated by the arrow 53, discharging and preventing entrance of any dirt or chips.

As a'result, although the chamber 50 will be lled with oil, such pressure will be substantially atmospheric, due

to the release of anyexcess liquid through the grooves 51.

'The grooves 51 also balance the coolant pressure in the chamber 50 on either side of plug I.

Sometimes at higher rotational speeds it is necessary to provide additional venting for the chamber or space 50 and additional grooves may be provided in the plug I or relief otherwise may be provided into the chamber 50. yInsome instances, particularly athigh rotational velocities of the dn'll M, the centrifugal pressure of the liquid that lls up the chamber 50 may press against the exterior of the face 54 to add to the thrust applied to the face 47 to give extra pressure eifect.

Where it is Ydesired Yto use centrifugal pressure, the

terial selected for these contact faces `designed `so as to increase the Vcoeflicient of friction. The angle should not be larger than 85fI and may range from 0 to 85 with an optimum value between 45 and 60.

By referring to Figs. 1, 2 `and 3, it -will 'bc noted that the contact face 58 is carried upon a relatively thin disc. The thinness of the disc will give less weight to the plug, but `at the same time the disc must be suiciently rigid to carry the thrust and torque applied.

In order to enable rapid change of drills without opening up the driver assembly or changing the safety driver K-I-L,v ya sub-driver R may be utilized as shown in Fig. 3. In Fig. 3 there is shown a driver extension 80 having an external groove 81 and 'a forwardly extending cup 82. Y

The cup 82 has a recess 83 to receive the extension 84 'of the sub-driver R. A threaded tip 85 is received in the tapped` socket `86. The head 87 will permit use of ya -wrench in installing and removing the drill and sub-driver assembly.

The safety device C of Fig. 1 constitutes `a push rod having -a reduced forward diameter portion 100 and a reduced rearwardly extending portion 1101. The rearward portion 101 is encircled by a spring 102 which normally biases the push rod C in the direction 103. The nut 104:1 will 'act `as `a stop in the forward position. Y

The tip 104 will fbe normally spaced from a plunger member 105 of a'limit switch D.

If the driver is forced inwardly, there will Ibe a con- .tactbetween the forwardly extending rod 106 `and the end 48 of the member K. This will result in contact between the elements 104 rand 105 actuating the limit Switch D to give a signal or to stopthe machine.

VThe slot'106b in the head 10651 permits'holding of the rod C when the nuts 104er is tightened up thereon.

The O-ring 107 will seal the member 100 in the passageway 108'in the spindle nose adapter G.

In the Yalternative safety arrangement shown in Fig. 4, the groove 81 will carryV the nose 120 of the bell crank lever I121. The bell crank lever 121 is pivotally mounted at 122.

The arm 123 carries an `adjust-able contact rod 124 Whichis held in any predetermined position by means of the nut 125. The rod 124 will contact the recipro- -cating member 126 of the limitswitch 127 to stop the sure of the coolant most satisfactorily to give the necessary thrust as against a reduced diameter piston surface, while using a larger diameter conical thrust surface to achieve the desired torque.

The device `as shown will eliminate or decrease the possibility of breaking drill in the work due to operator or machine failure or because of undue wear or chipping of the cutting edge.

Even though the drill is relatively fragile, there will be less breakage and a greater production of perfect Work pieces and a minimum of scrap.

The safety driver device of the present application is particularly suited to high production machines, and especially for fully automatic, -multi-spindle machines.

The safety device of the present application will protect the drill from excessive vtorque and excessive thrust, and not only will limit these forces -but furthermore can signal the operator and/ or provide an automatic control in case of overload.

The safety driver device of the present invention will accommodate itself to a wide variety of coolant pressures with varying drill diameters, and will also accommodate a wide variety of feed rates and Work materials with varying conditions of wear at the cutting edge,

The hardened plate N may be made integral instead of separate from the cap P so that the plug will be pressed directly against the inside face of the cup.

Instead of a separate cylindrical insert H to carry the rearward extension K of the plug J, the element G may itself carry the extension K, as well as the periphery of the plug l.

As many changes could be made in the above safety drivers for gun drills, and many widely different embodiments of this invention could be made without department from the scope of the claims. It is intended that all matter contained `in the above description shall be interpreted as illustrative and not in a limiting sense.

Having now particularly described and ascertained the nature of the invention, and what manner the same is to be performed, what is claimed is:

l. A drill having a rotating carrier with a chamber having a small diameter chamber and a large diameter chamber, a conduit to feed coolant under pressure into said small chamber and a drill shank carrying plug having a small diameter piston in said small chamber and a large diameter piston in said large chamber, said large piston and large chamber having cooperating annular frusto conical friction contact faces to cause said drill to rotate with said carrier, said faces being forced together by the pressure of said coolant on said small piston in said small chamber.

2. A driving arrangement for a boring and drilling mechanism comprising a rotary carrier having a cylinderlike chamber system, a plug driver including a rearwardly extending plug guide member positioned in said chamber system, a forwardly extending drill shank carried by said driver, said driver acting as a piston aud a conduit to supply coolant under pressure to drive said driver against one end of said chamber and hold it there under friction upon rotation so that the driver and carrier will turn together, the contacting friction faces of said driver and the end of the chamber being annular and extending around the interior periphery of the chamber.

3. The arrangement of claim 2, said plug having a stepped peripheral portion with a conical contact face and said chamber also having a conforming conical contact surface.

4. The arrangement of claim 2, said plug and drill shank having pasageways therethrough to pass the coolant through said chamber to the work being drilled and bored.

5. The arrangement of claim 2, a safety stop device actuated by movement of said plug through said chamber upon excessive load on said drill shank in the direction against coolant pressure.

6. The arrangement of claim 2, said driver having a small central face on said guide member acted upon by said coolant pressure to cause the friction contact.

7. The arrangement of claim 2, the chamber system having a small chamber to receive the guide member and large chamber to receive the driver with small clearance so as to limit leakage of coolant past the periphery of the guide member.

8. A drill arrangement having a separate housing, a rotatable spindle, bearings rotatably mounting said spindle in said separate housing, a rotating spindle driver adapter carried by said rotatable spindle, a rotatable drill driven by said spindle, said adapter having a large `diameter piston chamber at the side adjacent the drill and a smaller diameter piston chamber communicating therewith at the side away from the drill, both having the same axis as the spindle, a spindle driver plug carrying said drill having a large diameter at piston disk mounted to reciprocate in said large piston chamber and -a small diameter elongated plug piston connected to the flat piston disk and extending in the direction away from the drill and received in and mounted to reciprocate in said smaller piston chamber, a conduit rto feed coolant under pressure into said chambers and to press the piston disk and plug piston toward the ends of the chambers adjacent the drill, the periphery of the interior of said large chamber at the drill side and the periphery of flat piston disk at the drill side having contacting bevelled driving faces which cause -the disk and the drill to turn with the spindle when said driving faces are pressed together by saidcoolant pressure.

References Cited in the le of this patent UNITED STATES PATENTS 1,317,711 Landgra Oct. 7, 1919 1,760,310 Miller May 27, 1930 2,237,692 Stewart Apr. 8, 1941 2,483,613 Benbow Oct. 4, 1949 2,562,170 Busemeyer July 31, 1951 FOREIGN PATENTS 586,385 Great Britain Mar. 17, 1947

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