US 2374552 A
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Description (OCR text may contain errors)
April 24, 1945- M. F. MAR|N| I 2,374,552
. COUNTERSINKING TooL Filed July 15, 1944 IN VEN TOR.
Patented Apr. 24, 1945 UNITED STATES PATENT 'OFFICE l QOUNTERSNKING TOOLl Mario F. Marini, Swedesboro, N. J. Application `July 15, 1944, Serial No. 545,031 2 claims. (c1. w-ras) The pre-sent invention relates to countersinking tools or reamers and it relates more particularly to a newand improved countersinking tool or broaching bit.
An object of the present invention is to provide a new and improved countersinking tool or reamer or broacher. Another object of the present invention is to provide a new and improved countersinking tool or reamer or broacher which will be positively guided in the hole being worked.
Other objects and advantages of the present invention rwill be apparent in the following vdetailed description, appended claims andaccoml panying drawing.
lng the countersinking operation so that the bevel formed very often is not uniform and is offcenter Arelative to the axis of the hole.
Accordingly, the present invention contemplates a new and improved countersinking tool or' reamer or broacher which will be positively guided axially of the hole so that the final bevel formed will bel accurate and properly centered.
Generally speaking. the present invention cornprehends a cuntersinking tool having inclined cutting-edges of appropriatetaper and having a guide detachably connected forward of the cutting-edges; the guide being adapted to t Within the hole with slight clearance so as to prevent wobbllng or other lateral movement of the cutting-edges during the countersinking operation. The present invention further contemplates the useof a plurality of diiTerent-diametered guides whereby the same broacher can be used for different-sized holes. For the purpose of illustrating the invention,
there are shown in the accompanying drawing forms thereof which are at present preferred, since the same haveA been found in practice to give satisfactory and reliable results, although it is to be understood that the various instrumentalities 4oi' which the invention consists can be variously arranged and organized and that the invention is not limited to the precise arrangement/s and organizations of the instrumentalities as herein shown and described.
Referring to the accompanying drawing in which like reference characters indicate like parts throughout:
Figure l represents a perspective view of one embodiment of the present invention as it appears in'uSeI Darts being broken away better to reveal the construction thereof.
Figure 2 represents an exploded elevational view of the embodiment of Figure l.
Figure 3 represents a bottom plan view of the countersinking tool of Figure 2, as it appears when the guide and nut are removed.
Figure 4 represents a view partly in perspective and partly in cross-section of the guide of Figures 1 and 2.
Figure 5 represents a fragmentary view partly in elevation and partly in cross-section showing the countersinking tool of Figure l as it appears in use inra larger-diametered hole and with a larger-diametered guide.
Figure 6 represents a fragmentary view partly in elevation and partly in cross-section showing another embodiment of the present invention as Y gripped by .the chuck I3 Vof a drill-press or the like (not shown).
A plurality l for example four) of taperedcutting-edges Il are formed at the lower end of the body portion II;the cutting-edges Il being relieved as at I5 in conventional manner.
A post I6 extends from the forward or lower face Il of the body portion II generally (along the axis of said counterbore III. The post I6 (which ha's a relatively small transverse dimension) has a square (or other non-circular) stem portion I8 which is nearest the body portion II and an externally screw-threaded stern portion I9 formed at the outer end of thesquare portion i8; the sides of the square portion I3 being formed as generally tangential extensions of the screw-threaded portion I9 as shown particularly in Figure 3.
A generally cylindrical guide 20 is adapted to be removably mounted upon the post I6 of the counterbore I 0. tured; the .aperture having a square cross-section as at 2| (adapted to fit snugly about the square portion I8 of the post i6) andhaving a circular cross-section at itslower or outer end as at 22 (adapted to t about the screw-threaded portion I9 of said post I6 with a slight clearance).
The guide 20 has an axial dimension somewhat less than the length of the post I6 so that, when the guide is tted upon the post. enough of the screw-threaded portion I9 of saidA post I E Vwill protrude to permit a nut 23 to be screw-threadedly mounted thereon to lockthe guide 20 in position as shown in Figure l.` In the embodiment of Figures l to 5, the guide 2li has a diameter generally the same as the baximum diameter of the lower face I'I of the counterbore I0; this diameter being very slightly less than the diameter of. the opening to be countersunk.
The guide 20 is axially aper- Thus, when the countersinking tool of the present invention is inserted Iwithin the hole or openv ing 24 to be roamed or broached or countersunk as shown in Figure l. the guide thereof will fit snugly within said opening 24 with relatively slight Iclearance. Thus, the forward or Working end of the countersinking tool will be kept from -4 wobbling or other undesirable lateral movement or shifting during-the countersinking operation and will be maintained in Iposition generally axially of the opening so that the bevel formedthereby will be accurate anduniform throughout.
- It is apparent that the counterbore Illof Figure l can be used to countersink aplurality of different-'diametered openings due to the upward and outward ilare of the cutting-edges I4. That is, with relatively smaller-diametered openings (i. e. openings only slightly larger in diameter than the lower face Il), the bevel will be formed by the lower smaller portions of the cutting edges Iii while with relatively larger-diametered'openings (i. e. openings slightly smaller in diameter than the maximum diameter of the body portion I I), the bevel will be formed by the larger upper vmost portions of the cutting edges I4.
Thus, where the countersinking tool is to be used in the relatively smallerdiametered`open ing 24 as stated hereinabove, the guide employed will be like that shown in Figures l, 2, and 4; that is, a guide having generally the same diameter as the lower face I1 as stated'hereinabove When, on the other hand, vthe countersinking l' ting-edges may be made with a 60 taper as shown in the drawing or, instead, may be made with a 45 taper or a 65 taper or any other desired taper. The number of cutting-edges and the shape thereof may also be varied through wide limits depending upon the type of operation to be done and the nature of the 'materialto be worked.
- The countersinking tool of thepresent invention, when used with a proper-diametered guide.
ispositively centered in the opening and insures an-even chamfer or bevel and even removal of burrs regardless of whether it is manipulated by adrillpress or a brace-and-bit or any other suitable tool.
tool is intended to be used in a' larger-diametered Opening 24a -asshown in Figure 5, a. Ingen diametered guide 2li-a is employed; the guide 20-a having a diameter greater than that of the face il and slightly less than that of the openf.
ing 24-a so that, again, the countersinking tool is maintained in proper axial alignment with the opening during the forming of the bevel by the upper portions of the cutting-edges I4.
In Figure 6 I have shown another embodiment of the present invention. The embodiment of Figure 6- includes a counterbore I Ila having a body portion iia, cutting edges Il a and a lower` face ii-a similarto those described in .connection with the embodiment oi Figure 2 but having an axial post 2E .extending downwardly from the face i'i-a. The post 25 is externally screw-threaded generally through its length with a right-hand thread.
Upon the post 25 there tachably mounted a guide 26 which is provided with an axial internally screw-threaded opening adapted'to receive said post 25. It is apparent that right-hand rotation of the countersinking tool during the counterboring operation will tend to tighten the 'guide 26 upon the post 25.
While the guide 2S of Figure 6 has a diameter generally the same as that oi the lower face I'i-a,
' so that the countersinking tool is adapted for use withthe smaller-diametered opening 24 as shown lin Figure 6, it is apparent that the guide 26 could be made with a larger diameter to permit the countersinking tool to be used in the larger-diametered opening 24a. i.
The novel countersinking tool of the present invention is adapted quickly and easily to form bevels or chamfers in openings as described hereinabove and also to remove burrs on the inner edge of holes such as might be formed, for. ingstance, in cutting pipes orthe like.
The size and vshape of the cutting-edges can be varied considerably. Thus, for example, the Cutlis adapted to be de' cylindrical The present invention may be embodied in other specic forms without departing from the spirit or essential attributes thereof, and it is thereforeA desired that the present embodiments be consid--v ered inall respects as illustrative' and not reof circumferentially-spaced tapered cutting-edges formed at the forward end of said body portion, said cutting-edges being adapted to form a bevel 'at the end of a hole or the like when said tool is axially rotated,l a reduced post extending axially -from the forward" end of said body portion, said *post having a non-circular portion, a generally centering-guide adapted non-rotatably to t over said non-circular portion, .and'means for fastening said centeraxially-apertured ing-guide upon said post, said centering-guide being adapted to enter said hole ahead of said cutting-edges and having a diameterrslightly less than that of the hole, whereby it will'centersad tool generally axially of said hole during the cutting operation and will tend topreventlateral shifting of said cutting-edges.
2. A countersinking tool or the like comprising a generally cylindrical body portion, a reduced shank extending axially rearward from said body portion and adapted to be gripped by a chuck or the like for rotation of said tool, a plurality of circumferentially-spaced tapered cutting-edges formed at the forward end of said body portion, said cutting-edges being adapted to form a bevel at the end of a hole or the like when said tool is axially rotated, a reduced post extending axially from the forward end of said body-portion', said post having a generally polygonal cross-section adjacent said body portion and being screwthreaded -at its outer end, a generally cylindrical axially-apertured centering-guide adapted nonrotatably to t over the polygonal vportion of said post, and a" nut adapted screw-threadedly to engage with the end of said post and to lock said centering-guide thereon,` said centering-guide` being adapted to enter said hole ahead of said cutting-edges and having a diameter slightly less than that of the hole, whereby it will center said tool" generally axially of said hole during a cutting operation and will tend to prevent lateral shifting of said cutting-edges.
MARIO F. MARINI.