US3545554A - Drill bit with staggered teeth - Google Patents

Description

United States Patent Inventor App], No.

Filed Patented Assignee Allen E. Bar-dwell Princeton, New Jersey Dec. 3, 1968 Dec. 8, 1970 Trident Industries Inc.

Princeton, New Jersey a corporation of Delaware, by mesne assignments DRILL BIT WITH STAGGERED TEETH References Cited UNITED STATES PATENTS 5/1915 Buscavage 3/1917 Lane 6/1957 Stokes 8/196] Pennington I1 12/1964 Cleary Primary Examiner-James A. Leppink Attorney-Kingsland, Rogers, Ezell, Eilers & Robbins 8 Claims, 5 Drawing Figs.

US. Cl 175/398, 175/412, 175/414 Int. Cl F2 lc 13/00, F2lc 13/06 Field of Search 175/379, 398, 399, 412, 414

ABSTRACT: A drill bit for gravity drop drills and other percussion drills in which teeth extend outwardly from the end of i the bit different distances, that is, the teeth are of or are at different drilling heights.

1 DRILL arr WITH STAGGERED TEETH BACKGROUND or THE INVENTION 1 Field of The Invention The present invention relates generally. to percussiondrilling, as in rotary air hammer drilling and in cable drop I drilling, and more particularly to a novel drill bit incorporating opposing teeth which are staggered vertically or are set at or i are of different drilling heights, that is, one tooth extends outwardly from the end of the bit further than the other.

2. Description of the Prior Art As is stated in applicant's copending U.S'. Pat. application Ser. No. 661,560, filed Aug. 18, 1967, there'has long existed the need fora percussion drill bit which will reduce materially the recrushing of rock material previously cut and which will materially increase the inches per hour drilled over standard SUMMARY or THE INVENTION Broadly, a preferred embodiment of the present novel percussion drill bit includes a streamlined shaft or housing sup porting two spaced opposed blocklike teeth at the lower end, a which may be of the expandable type'as illustrated in the drawings. Each tooth includes an elongated cutter insert of carbide or other suitable material. The .teethmay be of tooled steel. One tooth extends outwardly from th'e end of the bit further than the other, hence, is of greater drilling height, or has such greater effective drilling height, than the other, which increases the cutting effect of the bit byincreasing the unit load and, consequently, the cutting rate per hour of the drill.

This novel arrangement also substantially eliminates pinching by carbide inserts, hence, reduces breakage to a nominal percentage by drilling an oversized hole allowing the remaining or opposing carbide to be free from pinchingand breakage that could occur in a tight hole. The staggered principle causes a larger hole diameter to be drilled as the lead tooth kicksv outwardly upon impact with hole bottom.This larger diameter hole prevents the two opposing carbides from pinching in a tight hole. The high unit load created by one carbide, rather than two, results in faster drilling.

Thus, an object of the present invention is to provide a novel drill bit which is constructed to increase the cutting effect thereof over other bits, hence, to increase the drilling rate per hour of the drill-of which it forms apart. 1

Other objects are to provide a novel drill bit which reduces carbide insert breakage to a nominal percentage, which is constructed to include the principles of the present invention. The bit 10 includes a shaft 12 having athreaded, reduced upper end 14 and a lower end 16 having two cavities or chambers 18 open at the ends and bottom and separated by a depending partition or wall 20.

A tooth 22 of block form including a round hole 24 with an enlarged leading portion 26 and having an insert 28 of carbide or other suitable material and of the configuration shown in the drawings is mounted in one cavity 18. A second tooth 30 extending a lesser distance outwardly from the end of the bit,

- hence, of shorter drilling height than the tooth 22, but otherwise the same except for a threaded hole 32 instead of the hole 24 is mounted in the other cavity 18. Successful experimental teeth 22 have ranged from one-eighth inch to one-half inch greater in drilling height as defined above than associated teeth 30. With much less the carbides tend to stick and with much more the crushing effect of tooth 30diminishes sharply. The teeth 22 and 30 can be of the sameheight, of course, with the former shirnmed or otherwise positioned to extend below the latter to attain a greater effective drilling height. The teeth I 22 and 30 may be of .solid good tool steel. The tooth 30 will crush cut rock. A heavy bolt 34 with a head 36 extends through the hole 24, a hole 38 in the partition 20, and threadedly engages the hole 32 to maintain the teeth 22 and '30 in operative positions. The hole 38 is a little larger than the diameter of the bolt 34 to prevent undue impact on or contact with the bolt 34 in drilling to prevent stressing or binding of the bolt 34. It is understood that variations may be made in the f teeth wear in drilling.

It will be further understood that the novel aspect of the present improvement of incorporating teeth of selected dif- 3 ferent drilling heights or positions extending different distances from the end of the bit may be incorporated in stationary teeth as well as adjustable teeth-Additionally, it may be included in percussion and other drill bits having more than two drill teeth, as three or four. For greatest'effectiveness in a highly effective, which is adapted to function "at its increased drilling rate for extended intervals, which is of sturdy construction, which is adapted to multidrilling usage, and which otherwise fulfills the objects and advantages sought therefor.

BRIEF DESCRIPTION OF THE DRAWINGS DESCRIPTION OF PREFERRED EMBODIMENT Referring to the drawings more particularly by reference numerals, 10 indicates generally a cable percussion drill bit four-tooth bit, for example, the teeth should be in the form of an X" and not at The present novel drill bit is highly effective in achieving the sought objectives. Faster trouble free drilling under comparable conditions are attained'than with other bits.

It is apparent that there has been provided a drilling bit which fulfills the objects and advantages sought therefor.

It is tobe understood that the foregoing description and the accompanying drawing have been given by way of illustration and example. It is also to be understood that changes in form of the elements, rearrangement of parts, and substitution of equivalent elements, which will be obvious to those skilled in the art, are contemplated as within the scope of the present in vention which is limited only by the claims which follow.

Iclaim:

l. A percussion drill bit including a main body, at least two active drill teeth secured in said main body, one drilling tooth extending a-greater distance outwardly from the end of the bit than the other and being of greater drilling effectiveness than the other, said one drilling tooth being the primary drilling element and effective determinent of hole cross section, the other of said at least two active drill teeth being a secondary drilling element operating within the hole cross section basi- 5. The drill bit of claim 2 in which at least the tooth of eighth inch more than the other. greater effectiveness drilling has a carbide drilling insert 8. The drill of claim 1 in which said one drill tooth extends 6 The drill ofclaim l in which said teeth ar adj stabl outwardly from the end of the bit between substantially one- 7. The drill of claim 1 in which the said one drill tooth ex eighth and One-half inch'more than the otherstends outwardly from the end of the bit suhstantially one-

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