US2939684A - Cutter for well drills - Google Patents

Description

June 7, 1960 Ly/e Z. Pay/7e INVENTOR.

ATTORNEY June 7, 1960 L. L. PAYNE 2,939,684

CUTTER FOR WELL DRILLS Filed March 22, 1957 2 Sheets-Sheet 2 -II mill/7.

Zy/e Z. Pay/7e INVENTOR. 311%AM ATTORNEY United States Patent 21,939,684 CU'ITER FOR WELL DRILLS Lyle L. Payne, Houston, Tex., assignor to Hughes T Company, Houston, Tex., a corporation of Delaware Filed Mar. '22, 1957, Ser. No. 647,788

7 Claims. (Cl. 255-349 ,The base metal of the cutter body is conventionally tough and strong but is notsufliciently abrasion resistant to provide adequate distintegrating action upon the wall of the well bore to maintain full gage of the bore thoughout the useful life ofthe remainderof the cutter. To overcome this dimculty, it has been pr posed toIsuperpo e a layer of wear resistant metal upon he outer ends of the heel teeth and the adjacent metal of thecutter uch layer comprising a carbide, such as paiticles of u asten carbide, ecured inplace by a matrix of suitabl m t l such as mild steel applied by a torch so that the m rix me al wets the s rface of the base met l of th cutter and the carbi es t us providing an effective interbond to hold the particles in Place to serve their intended purpose.

To facilitate application ofthe layerof wear resistant metal upon the cutter body it has also been proposed'to provide radially extending ribs of the base metal on the gage surface of the cutter and 'to'then apply wear resistant material and matrix metal bonded to the base metal and of a depth that the gage surface is flush with the crests of the ribs.

Such prior art structures have-been found to be inadequate, especially when drilling hard rock formations, to assure maintenance of gage, or diameter of the bore hole,

I throughout the useful life of the remainder of the cutter.

Thus, for some time prior to withdrawing and replacing the bit a tapered hole is being drilled; Then the'succeeding bit, which is of full gage, must ream the tapered hole before it reaches bottom. This reaming operation is time consuming and also effects destructive action upon the new hit and especially upon the gage cutting portion thereof whereby the useful life of the bit is'materially reduced. in some cases the new hit is rendered unfit for advancing the bore and another new bit is required before further drilling is resumed.

The principal 'difiic =ty arises from initial chipping or breaking away of the wear resistantmaterial at the outermost portion of the gage surface. fiance the composite wear resistant material and its matrix metal are relatively brittle the chipping action is progressive thus causing socalled heeling over or reduction of gage beginning at the point of maximum diameter of the roller cutter and ultimately leading to complete dest uction of the gage surface. This of course gives rise to under gage hole as well as early failure of the cutter.

It is therefore the primary object of the invention to provide a structure'whi'ch' minimizes the difficulties to which reference has just been made.

The invention comprehends the provision of a gage cutter 1 and integral with the heel teeth 5 "ice fac mpr sing areal deposits of wear esistant material k d p by rib f ba e m al of he cu ter body extending transversely of the direction of the principal destructive forces to which the gage cutting portion of the cutter is subjected when in normal use. Such forces are directed substantially radially inwardly along the gage surface. i

An ther obj ct is to p o d a sag cut ng structur which may be em odi d in ny typ of rollin cu ter havin a sag cu ting fun i n- Still another an more specific object is. t provide a rolling cutter having bottom. cutting elements wh ch cu th ou r bot om po ion. of. the we bore nd a Web inter onne ting the outer e ds ot said elem n ..the ou surface of aid web e ng a sage urface having spaced an ular ri s. of the a metal o the cutter andwea r is an materiai fill ng the p c e ween suc es ive ribs and bonded thereto.

T ese and. her o je ts; w be mo e ully pparen f m th f wing r p n and he accompanying drawings in which; 1 I

Fig. 1 is a side elevational view of a cone type cutter em yin th n ent ig-2 s a iew showing in e e ati n the sage f he rcut a p ion f th ea ist nt, material being.

broken away to enhance the showing of the structure;

Fig. 3 is a sectional view, taken'on line 3-3 Fig, 2;

Fig.4 is a sectional view ta ken'on line 4 4- in Fig; 2; Fig; 5 is a side elevational'view of a side roller type of cutter embodying the invention. Theinvention as shown in Figs. 1 and 2 comprisesa cone type cutter jl contoured internally as shown generally at 2 (Fig. 2) to receive bearing elements and a mounting shaft (not shown) upon which the cutter revolves as is well lgnown in the art. The cutter body 1 is symmetrical about its axis of rotation and is provided on'its arcuate bottom cutting portion 3 with rows of cutter teeth 4 and 5 the latter of which are known as heel teeth and an individual tooth is referenced at 6. The base metal of the cutter 1 and the teeth thereon is an' alloy steel and may be fortified against abrasion by suitable heat treatment or selective placement ofwear resistant material especially upon the flanks or ends of the teeth. Since such specific structure is relatively conventional and is not specifically concerned in the present invention, a general reference only is made thereto. The gage surface or gage cutting portion lti'compr ses an intermpted web 11 which is'a component part of the at their outer ends. it is to be noted that the gage surface 510 is generally conical, or frusto-conical, and intersects the bottom cutting portion 3 at 12, the maximum diameter of the cutter. It is at this point, which rolls at the juncture of the bottom and the side wall of a well bore that the most excessive stresses and abrading action are incurred. Because of the rolling action of the cutter the stresses are directed substantially radially inwardly of the cutter and initiate breakdown of gage structure at the point 12.

Reference to the web 11 as interrupted means that :at

intervals the web is cut away between successive h'eel teeth 6 as shown by the notches 13. Preferably theflside walls 14 of each of these notches follow the flanks of the two teeth inwardly therefrom. Also the gage snrface is recessed inwardly from each of the notches 13 .as shown at 15 This notching and recess-ing enhances ventilation of the gage structure to minimize grinding action upon formation material which has been severed and which tends to wedge between the gage surface and the wall of the hole being drilled. This yentilation is further enhanced by radial grooves 16 in the gage surfaceQ-Wwhich grooves are approximately or slightly deeper than the wear resistant portion of the gage surfacelt).

Patented June 7, 1960' ber which depends upon the amount of ventilation necessary for the type of formation being drilled.- Especially if there is an odd number of heel teeth 6 in the row 5, the

*number of teeth interconnected by uninterrupted portions of the web 11-will vary.

An important aspect of the invention resides in that portion of the gage surface 10 intermediate the notches 13 and the grooves 16. As best seen in Figs. 2 and 3 this feature of construction is effected by cutting a plurality of concentric grooves 20, 21, and 22 in the outer face of the web 11 leaving upstanding concentric ribs 23, 24, and 25 of a height that their crests lie upon, or substantially upon, the finished gage surface 10 of the cutter. v

A body of wear resistant metal 216 is then deposited in each of the groove segments and bonded to the bottoms of the segments and the side walls of the ribs 23, 24, and

"25 as best seen in Fig. 4. Preferably, though not limited thereto, the body of metal 26 comprises particles of a carbide, such as tungsten carbide, interbonded with each other and with the adjacent base metal of the cutter 1 by means of a suitable matrix metal such as mild steel or a suitable alloy.

It is here noted that the-outermost groove 20 extends to the point 12 of the cutter and that hence the outermost body of metal 26 engages the bottom of the well bore at .the juncture of the bottom with the side wall of the bore. While it is uncertain as to the reason for the superior qualities of the cutter thus far described it is believed that the rib 23 of basemetal of the cutter serves to stabilize the adjacent body of wear resistant metal against chipping or breaking away. In any event if excessive weight is applied and chipping or breaking away occurs suchchipping or breaking extends only to the adjacent rib of base metal and does not extend a major portion or all the way across the gage cutting portion 10.

drills, a series of substantially longitudinally crested heel Fig. 5 is similar to Fig. 1 but shows a rolling cutter of the type usable as side cutters on cross roller bits or as cutters on reaming bits to maintain gageof the hole cut thereby. Like parts are identified by like but primed reference characters.

By way of summary it is pointed out that the bottom cutting portion and the gage cutting portion 10 of the cutter 1 are referred to as generally conical. While generally conical, or frusto-conical, surfaces are illustrated and described it is to be understood that reference is had proved roller cutter for well drills and more particularly 7 a cutter having as a component part a gage cutting structure which facilitates the maintenance of gage throughout the usefullife of the cutter.

The invention claimed is:

1. A rotary drill cutter comprising a frusto-conical body having a series of circumferentially spaced longitudinally extending heel teeth on one end thereof, a circumferential web joining the outer ends of at least some of said teeth andv forming an outwardly facing frusto conical gage surface, a plurality of concentric grooves in the face of said web, and a wear resistant material filling said grooves and bonded to the sides and bottoms thereof.

2. A rotary drill cutter comprising a frusto-conical body having a series of circumferentially spaced longimaterial filling said .4 outer face, a plurality of concentric grooves in said-outer face of the web transecting said radially extending grooves, and a wear resistant material filling each of said concentric grooves and bonded to the sides and bottoms thereof.

3. In an approximately conical shaped cutter for well drills, a series of substantially" longitudinally crested heel teeth thereon, a circumferential web joining the outer ends of said teeth and forming an outwardly facing frustoconical gage surface, said web having a crest extending to approximately the same height as said heel teeth, a plurality of concentric grooves in the face of said web, and a wear resistant material filling said grooves and bonded to the base metal of the cutter.

4. In an approximately conical shaped cutter for well drills, a series of substantially longitudinally crested heel teeth thereon, a circumferential web joining the outer ends of said teeth and forming an outwardly facing frustoconical gage surface, said web having a crest extending to approximately the same height as said heel teeth, a plurality of concentric grooves in the face of said web, the outermost of said grooves extending to the crest of the web, and a wear resistant'material filling said grooves and bonded to the base metal of the cutter.

5. In an approximately conical shaped cutter for'well :drills, a series of substantially longitudinally crested heel teeth thereon, a circumferential web joining the outer ends of said teeth and forming an outwardly facing frustoconical gage surface, said web being cut away between successive heel teeth at spaced intervals whereby the teeth are interconnected in groups, a plurality of concentric grooves in the face of said web, and a wear resistant grooves and bonded to the base metal of the cutter. i

6. In an approximately conical shaped cutter for well teeth thereon, a circumferential Web joining the outer ends of said teeth and forming an outwardly facing frustoconical gage surface, said web having: its crest extending to substantially the height of said heel teeth, said web being cut away between successive heel teeth at spaced intervals whereby the teeth are interconnected in groups, a plurality of concentric grooves in the face of said web, the outermost of said grooves extending to the crest of the web, and a wear resistant material filling each of said grooves and bonded to the base metal of the cutter.

7. A rotary drill cutter for earth boring drills comprising a body having a pair of integral oppositely extending frusto-conical portions symmetrical about a common axis of rotation and having a common base intermediate the ends of the cutter body, one of said frusto-conical portions having a series of circumferentially spaced, longitudinally extending heel teeth thereon, the. other of said frusto-conical portions forming a gage surface, a web integral with said frusto-conical portions located at the common base, connected to said heel teeth and forming an extension of the gage surface, a plurality of concentric grooves in said gage surface and web, and a wear resistant material filling said grooves and bonded to the cutter Morlan Dec. 18,

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