US2706433A - Drill bit slotter - Google Patents

Description

April 19, 1955 R. s. MAYO DRILL BIT SLOTTER 3 Sheets-Sheet l Filed Sept. 3, 1952 IN VENTOR Robert 5 .Mayo. BY 6 P ATTORNEY April 19, 1955 Filed sep 1952- R. s. MAYO DRILL BIT SLOTTER 3 Sheets-Sheet 3 4 ,ZNVENTOR ATTORNEY United States Patent C) DRILL BIT SLOTTER Robert S. Mayo, Lancaster, Pa. Application September 3, 1952, Serial No. 307,670 9 Claims. (Cl. 90-15) This invention relates to metal cutting machines and more particularly to cutting machines of the class mtended for slotting metal stock, such as drill bits, by means of a driven rotary cutter.

An important object of the invention is to provide a machine of the above character in which the cont nuously-driven rotary cutter is automatically fed 1nto engagement with the work and having means under the control of the workman for instantly arresting the travel of the cutter without the necessity for halting its rotation. For accomplishing this object, the invention contemplates the provision of a cutter carriage having a continuouslydriven nut mounted thereon adapted to travel along a helically-threaded shaft for feeding the rotary cutter into engagement with the work and manual control means for selectively locking or releasing said shaft for rotation to control the travel of the cutter carriage therealong.

Another object of the invention is to provide a machine of the above character which is especially suitable for milling slots in the points of drill bits for fitting such drill bits with extremely hard, wear-resistant bodies for enhancing the cutting action and lengthening the effective life of such drill bits. As examples of drill bits provided with such wear-resistant bodies reference is made to the patents of Joseph V. Emmons No. 1,887,372, granted November 8, 1932, and No. 1,977,845, granted October 23, 1934.

Another object of the invention is to provide a portable machine of the above character that is comparatively small in size and simple in construction, and which may be readily accommodated within the space limitations and to the available power sources of small machine shops usually found at mines and excavation projects.

Other objects and advantages will be apparent from the following detailed description of a preferred embodiment of the invention, reference being had to the accompanying drawing, in which:

Figure 1 is a perspective view of a drill slotting machine;

Figure 2 is side elevation of the machine;

Figure 3 is an end elevation of the machine;

Figure 4 is a cross-sectional view taken on the line 44 of Fig. 3; and

Figure 5 is a transverse cross-sectional view taken on the line 55 of Fig. 2.

In the drill slotting machine shown in the drawings, the frame comprises an elongated, rectangular bed plate 1, a rectangular top plate 2 vertically spaced thereabove and four upright slide rods 3 extending between the bed plate and top plate. Adapted to travel up and down along the slide rods is a hollow box-shaped cutter carriage 4 having apertured lugs 5 at its corners encircling the guide rods. A horizontal cutter shaft 6 is journaled in antifriction bearings 7 in the opposite side walls 4a of the carriage and one end of the cutter shaft is axially recessed to provide a chuck for receiving a spindle 8 carrying a milling cutter 9. The outer end of the spindle is axially supported in centered relation by a tapered pin 10a held in a bracket 10. This bracket is slidably adjustable upon a stud shaft 11 projecting outwardly from a side of the carriage and overlying and extending parallel to the spindle 8.

For rotating the cutter shaft 6 and also for imparting vertical travel to the carriage 4 a drive shaft 12 is supported in antifriction bearings 13 in the side walls 4a of the carriage so as to extend parallel to the cutter shaft. A small spur gear 14 on the drive shaft 12 engages a ice 2 large spur gear 15 on the cutter shaft 6, the gear ratio being approximately 1:4. A pulley 16 isdemountably mounted upon a projecting end of the drive shaft, the arrangement being such that a gear, hand-crank or other type of driving coupling may be substituted for the ulley.

p Also fixedly carried on the drive shaft 12 is a worm 17 which meshes with a worm wheel 18 forming the lower end of a nut 19 which latter is centrally threaded and mounted to travel along a helically-threaded carriage feed shaft 20. The feed shaft 20 is supported in antifriction bearings 21 mounted in the top plate 2 and extends vertically downward into the interior of the carriage 4. The wall closing the upper side of the cutter carriage is formed with a downwardly-directed boss 22 which is provided with an oversize clearance opening 22a to allow passage for the feed shaft 20, and the feed shaft is held in centered relation to the opening in the boss 22 by antifriction bearings 23 interposed between the nut and the boss. The arrangement is such that the nut is vertically movable with and as a part of the carriage but is rotatable relative thereto.

From the foregoing description it will be apparent that when rotation is imparted to the pulley 16 the drive shaft 12, through the spur gears 14 and 15, will rotate the cutter shaft 8 and milling cutter 9, and will, simultaneously, through the worm 17 and worm wheel 18, rotate the nut 19 to raise or lower the carriage along the feed shaft 20.

The drive shaft 12, as has earlier been suggested, is adapted to be driven from any convenient source of power or even by a hand crank in lieu of the pulley 16 where no electrical or mechanical power is available. As one means for driving the drive shaft 12, an electric motor M is shown supported on a bracket B on the cutter carriage and operatively connected to the pulley 16 by a belt 24. The motor is driven so as to continuously rotate the drive shaft 16. As a safety measure, control switches (not shown) may be suitably provided in the path of the carriage to automatically cut off the motor when the carriage reaches the top and bottom limits of its travel along the slide rods 3.

For affording a manual control for instantly halting the travel of the carriage at any position along its path of travel, the carriage feed shaft 20 is extended above the top plate 2 and has fixed upon its upper end a collar 25 elongated to define a laterally projecting crank 26. A removable pin 27 is adapted to be inserted in a verticallydisposed opening 28 in the collar with its end footing within a recess 29 in the top plate 2 and located, in one position of the collar, in line with the opening 28. Thus,

- when the pin seats in the recess 29 the feed shaft 20 is held against rotation and when the pin is removed the feed shaft is free to rotate.

Any suitable type of clamp for holding a drill bit D to be slotted may be used in conjunction with the slotting machine just described. By Way of example there is shown on the drawing a drill bit holder 30 shiftably adjustable on a block 30a secured to the bed plate 1. The drill bit holder comprises a pair of clamps 31 located at laterally spaced apart positions and each clamp includes a fixed lower jaw 32 and a releasable upper jaw 33, the jaws being cradled for limited angular adjustment. The drill bit D may be shifted relative to the cutter and turned about its axis for adjusting the position of the drill bit before it is finally clamped in fixed relation to the path of travel of the cutter. The angular adjustment of the drill bit on the drill holder is desirable to allow cutting a slot in the bit even when the wings of the drill bit are out of relation with the flats of the hexagon or octagon constituting the side faces of the drill shank.

The operation of the drill slotting machine just described is as follows: The electric motor M having been connected to a source of current rotation is imparted to the drive shaft 12 by the belt transmission 24. Rotation of the drive shaft imparts slower rotation to cutter shaft 6 by reason of the reduction afforded by the-interengaging small and large spur gears 14 and 15 on the drive shaft and cutter shaft, respectively. Slow motion is simultaneously transmitted to the nut 19 from drive shaft 12 through the intermediary of worm 17 and worm wheel 18, the direction of rotation of the nut preferably being such as to cause the cutter carriage 4 to normally climb the helically-threaded shaft 20.

The drill bit D to be slotted having previously been clamped in the holder 30 and suitably positioned so that the path of travel intersects the drill point at the desired location and angle relative to the axis of the drill, the pin 27 is dropped into the opening 28 and when the collar 25 secured to the upper end of the feed shaft 20 rotates so as to bring this opening into alignment with the recess 29 in the top plate 2, the pin will drop into this recess and lock the feed shaft against further rotation.

The nut 19 will begin to climb the feed shaft carrying with it the milling cutter 9, which latter when it comes in contact with the drill bit will continue its upward travel, cutting a transverse slot in the drill point. The machine operator may desire to arrest travel of the cutter carriage without stopping rotation of the cutter or to instantly arrest travel of the carriage regardless of Whether the cutter continues to operate depending upon contingencies encountered during the milling operation. This may readily be accomplished by the operator by lifting the pin 27 out of the opening 28 which frees the feed shaft 20 for rotation in unison with the nut 19.

It will be appreciated that in order for the feed shaft 20 to rotate freely when the pin 27 is removed, the antifriction bearings 21 serve the important purpose of reducing drag upon the feed shaft 20. Likewise, the full weight of the cutter carriage resting upon the nut 19 produces substantial bearing friction between the threads of the nut and the threads of the feed shaft which tends to couple the nut and feed shaft together for rotation as a unit.

After the cutter carriage 4 has traveled upwardly a distance such that the milling cutter 9 has formed a slot entirely through the drill bit D, or alternatively, to a desired depth within the drill bit, the motor M may be shut off, the pin 27 released, and the feed shaft 20 reversely rotated by the operator by turning the crank 26 to return the shaft to its starting point, ready to begin another drill slotting operation.

While I have described the slotting of the drill bit by feeding the milling cutter upwardly relative to the drill bit, this is merely by way of suggestion and the cutter may be fed downwardly toward the drill bit if that is found more satisfactory. Also, instead of being fed vertically, the cutter carriage may be mounted to travel in a horizontal direction.

It is to be understood that various changes in construction and design may be made in the preferred embodiment of the slotting machine described and illustrated herein without departing from the spirit of the invention as set forth in the following claims.

I claim:

1. In a machine of the class described, the combination with a traversible carriage, a cutter shaft rotatably supported upon the carriage and means for rotating the cutter shaft, of means for traversing said carriage, said traversing means comprising a rotatable, helicallythreaded shaft supported against endwise displacement, a nut rotatably associated with the carriage and mounted for travel upon said helically-threaded shaft, means for rotating the nut and control means for selectively releasing or locking said helically-threaded shaft against rotation.

2. In a machine of the class described, the combination with a traversible carriage, a cutter shaft rotatably supported upon the carriage and means for rotating the cutter shaft, of means for traversing said carriage, said traversmg means comprising a rotatable, helically-threaded shaft supported against endwise displacement, a nut rotatably associated with the carriage and mounted for travel upon said helically-threaded shaft, a rotatable drive shaft, means for transmitting rotation between the drive shaft and the nut and control means for selectively releasing or locking the helically-threaded shaft against rotation.

3. In a machine of the class described, the combination with a traversible carriage, a cutter shaft rotatably supported upon the carriage and means for rotating the cutter shaft, of means for traversing said carriage, said traversing means comprising a rotatable, helicallythreaded shaft supported against endwise displacement, a nut rotatably associated with the carriage and mounted for travel upon said helically-threaded shaft, a rotatable drive shaft, transmission means comprising a worm and worm wheel for transmitting motion between the drive shaft and the nut and control means for selectively releasing or locking the helically-threaded shaft against rotation.

4. A machine of the class described comprising a machine frame including a plurality of vertical guide members, a carriage traversible along the guide members, a transverse cutter shaft rotatably supported upon the carriage, a vertically disposed helically-threaded shaft rotatably supported against endwise displacement upon the machine frame, a rotatable nut upon the carriage and mounted for travel upon said helically-threaded shaft, a transverse drive shaft rotatably mounted upon the carriage, power transmission means between the drive shaft and the cutter shaft and between the drive shaft and the nut and control means for selectively releasing or locking the helically-threaded shaft against rotation.

5. A machine of the class described comprising a machine frame including a plurality of vertical guide members, a carriage traversible along the guide members, a transverse cutter shaft rotatably supported upon the carriage, a vertically-disposed, helically-threaded shaft rotatably supported against endwise displacement upon the machine frame, a rotatable nut upon the carriage supporting the weight of the carriage and mounted for travel upon the helically-threaded shaft, a transverse drive shaft rotatably mounted upon the carriage, a pinion on the drive shaft engaging a pinion upon the cutter shaft for transmitting motion between the drive shaft and cutter shaft and a worm on the drive shaft and a worm wheel on the nut for transmitting motion between the drive shaft and the nut and control means for selectively releasing or locking the helically-threaded shaft against rotation.

6. A machine as set forth in claim 5 wherein the control means comprise a sleeve secured to the helicallythreaded shaft and a releasable locking pin intermediate the shaft and a recess upon the machine frame.

7. A machine as set forth in claim 5 including antifriction bearings for rotatably supporting the helicallythreaded shaft and for rotatably supporting the nut.

8. A machine of the class described comprising a machine frame having a bed plate, a top plate and a plurality of vertical guide members extending therebetween, a carriage traversible along the guide members, a transverse cutter shaft rotatably supported upon the carriage, a rotary cutter mounted on the cutter shaft, a vertically-disposed, helically-threaded shaft rotatably supported upon the top plate against endwise displacement and having its upper end projecting upward therethrough, a hand crank fixed to the projecting upper end of the helically-threaded shaft, a nut rotatably mounted upon the carriage and operatively engaging the helicallythreaded shaft for travel therealong a transverse drive shaft rotatably mounted upon the carriage, transmission gearing between the drive shaft, the cutter shaft and the nut for imparting rotation to the cutter shaft and the nut, and means for selectively releasing or locking said handle and helically threaded shaft against rotation.

9. A machine as set forth in claim 8 including workclamping means for holding the work in fixed position relative to the rotary cutter.

References Cited in the file of this patent UNITED STATES PATENTS 1,200,703 Bolkovac Oct. 10, 1916 2,188,447 Smith Jan. 30, 1940 2,276,757 Baines Mar. 17, 1942

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