US 2935906 A
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Description (OCR text may contain errors)
y 1960 R. w. AN'DREASSON 2,935,906
011. TUBE DRILL Filed July 1, 1957 ez INVENTOR.
United States invention relates to Tan oil tube drill and has particularly to do with that type of drill in WhlCh a passage is providedwithin the drill to carry coolant to the drilling-tip. v I
It has long been a problem to provide a proper drill for drilling oil holes in crank shafts, for example, or other such that machines must frequently be reversed to'avoid overloading or stopped for drill replacement.
The' present invention con-templates. the use of a drill which is formed from tubing in a manner in' which the flute is straight-formed by crushingin the opposite sides of the tube, after which the fluted; tube is twisted to provide the spiral shape, leaving passages within the. tube in each spiral land. This type of tube, while successful for certain types of drilling in orbrass, has been found'to be weak for drilling steel'fo'r other hard metals. 1 I
. It is an object of the present invention to utilize this inexpensive method of forming a drill and still provide adrill which is strong enough to accomplish its purpose.
This is done by providing on lthe outside of the drill a hardened coating which has suflicient strength rigidify the jdrilland prevent bending 'or twisting which will destroy the accuracy of thedrill and alsoto'provide the hard wearing surfaceywhich is a further advantage. It is another object to provide such a drill with a tip which is so adapted that it will provide a strengthening effect to the drill itself and prevent opening up which might otherwise occur in the shaped drill due to the dead-center action which tends to split a formed drill of this kind.
Another object of the invention is a provision for coolant access from the interior of the drill to the exterior of the tip.
Other objects and features of the invention having to do with details of construction will be apparent in the following description and claims.
Drawings accompany the disclosure, and the various views thereof may be described as;
Figure 1, an elevation of a completed drill with an applied shank. I
Figure 2, a view of the tube from which the drill is formed.
Figure 3, the tube in progress of manufacture showing the straight flutes in general configuration.
Figure 4, the drill after being twisted.
Figure 5, a sectional view on line 5-5 of Figure 1.
Figure 6, an end view on line 6 of Figure 7.
Figure 7, an illustration of the manner in which the tip is assembled to the drill shank.
Figure 8, an enlarged view of the assembled end and shank.
The drill is preferably formed of a tube of hardenable steel shown at 20, such as SAE 1020-1030 steel, which can be surface hardened by a carburizing process. As shown in Figures 3 and 4, the opposite sides of the tube are fashioned together in a suitable die to create flute deep, small holes. The problem'of'drill breakage'is 2,935,906 Patented May 10, 1960 .2 portions 22 and leaving land portions shown generally at 24.
In the embodiment shown, the walls of the tube are brought together from opposite sides; and if desired, the inner apices of the, flutes may be brazed together to provide additional strength. This, however, is not a requisite of the formation. The land portions consist of a margin 2r6with relieved portions 28.
In Figure 4, the drill is shown in twisted helical form .Wherein helical flutes and helical lands are provided. In twisting the body, the contacting portions of the web arebrought in. close relation, thus defining two independent passages in the drill body.
In the. method of forming, the tube may be either formed in cross section prior to. twisting or twisted at the same time that the cross section is being rolled into it. .After thedrillbody has been rolled, to the proper shape, it will be seen that the passages within the tube resulting from. the rolling operation aresegmental in shape at 30, each passage forming in cross section substantially a segment of the circle. Thus, all available area within the tube is utilized for the passage of coolant.
When the tool body is completed, a suitable shank 40 is"attached with suitable oil receiving holes, not shown, to co-operate with a fixture which provides oil and coolant. Prior to the'attachment of the tool shank and the by a carburizing operation which hardens the surface of thefto'ol to a' considerable extent relative to the core. However, a preferred method and embodiment of fastening the shank of the drill is to provide it with a bonded coating, such as that disclosed, for example, in the .1. United States Cole Patent 2,694,647, issued November The particular fuse coating which is preferred in connect-ion with this treatmentis acoating which has preferablyjciifremely hard metals, such as tungsten carbide andchromium bo'ride, but any useof the process disclosed'in this patent which applies a relatively hard surface to the drill shank is contemplated.
Another process which can 'be used is that known to the trade as Colrnonoy coating, which is a coating of metal sprayed onto the shank. It has been found that applying a coating of this type, as shown at 50 in Figure 5, greatly increases the resistance of the tube against torsional distorsion and bending. Drills so treated have been found to be very superior to drills otherwise formed; and in addition, they have a wearing quality against abrasion which is greatly increased over a normal drill shank.
Referring now to the tip construction, a tip 60 is shown in Figures 6, 7 and 8. This tip 60 is formed of a solid cutting tool steel or other equivalent material and is fluted at 62, each flute terminating in a cutting edge 64. The shank end of the tip is provided with a pair of dentate cusps 66 which engage recesses 68 formed in the outer walls of the end of the drill shank (see Figure 7). These cusps are brazed into the drill shank along with the other contacting surfaces of the drill shank and the drill end. The combination provides torque transfer at the outer walls which avoids a tendency to wedge open the drill.
The openings 30 may have their outlet through a surface recess 70 which is worked into the surface of the flute of the drill and to a depth that it will communicate with the segmental openings 30 when the drill end is joined, thus admitting egress and ingress of the coolant and lubricant.
With this arrangement, it" is unnecessary to the cutting end of the device and the resulting combination of the elements is stronger and less expensive than a tool where internal drilling is required,
Another construction, shown in Figured, which may be used, is the utilization of a hole 80 on eachland ofthe shank 20 just adjacent the tip 60} The cpolant has an outward reaction which tends to lubricate the drill and float it away from the side walls of the hole on a film of liquid and the flow is then downward to the tip and back. The margin 26 with the relieved surface 28 forms a flow path for the coolant on the'outer diameter of the drill to the cutting edges of the tip.
The steps in the making of the tool .in resume constitute first selecting a tube of proper steel asabpve indicated forming straight flutes in the tube withgashag'ged di twisting the tube by a orsion a p i at q of er u n i to e providing a inspf ext m ly, age
1 register with the flutes andlands at the end of t e tu the surfaces of the flutes of the tip being recessed inwardly adjacent the tube to communicate with the interior passages of the tube, and a thin, hard coating on all of y the surfaces of said tube molecularly bonded thereto to material on the outside of the tube molecularly bonded to the surface thereof, and subsequently fashioning a cutting end and attaching the cutting chi @Q the drill shank with a brazing operation or other equivalent,
The combination of the bonded coating and the burizing process can be utilized also to obtain resistance to torque and bending. a 1 i I claim:
l. A drill comprising a tube fashioned so that opposite parts of the tube will come into substantial engagement with each other leaving a lengthwise interior passage extending on each side of said engagement, Said tube being fashioned into twisted helical form having spiral flutes and lands, and a drill tip secured at hi end of the tube to receive a coolant from the passages within the tube, said tip having a plurality of cusp-like axial extensions on the end adjacent the tube to interengage axial recesses in the walls of said tube, means bonding the tip to the tube, said tip having flutes and lands which register with the flutes and lands at the end of the tube, the surfaces of the flutes of the tip being recessed inwardly adjacent the tube to communicate with the interior passages of the tube.
2. A drill comprising a tube fashioned so that opposite pasts of the tube will come into substantial en! gagernent with each other leaving a lengthwise interior create resistance to bending and torque stresses and to provide a hard wearing surface on said drill.
3. A device as defined in claim 2 in which the coating is that resulting from a carburizing process.
4. A device asdefined in claim 2 in which the coating is a combination of a carburized surface and a molecularly bonded surface relatively harder than saidftube.
5. A drill adapted to have coolant delivered to the cutting-tip through internal passages which comprises a helical web portion formed by the walls of the tube squeezed together, the remainder of the drill body comprising helical lands on either side of flute passages formed by the walls of said tube surrounding passages parallel with said web. portion, a separate, solid cutting tip aflixed to said body, and openings in the walls of said tu e Q 1 h ds f e la a j n the p c n t said passages and the outer surface of said tip to permit coolant to flow out and around said tip and back through said flutes.
References Cited the. file of this patent UNITED STATES PATENTS 2,6 98 ,10 Staufier -L Jan. 4,1955