US3244033A - Counterbore pilot - Google Patents

Description

April 5, 1966 s. w. JARDINE COUNTERBORE PILOT Filed April 19, 1965 FIGS l NVENTOR United States Patent 3,244,033 COUNTEREGRE PILOT George W. Jardine, 12 Lake Road, Walthsrn, Mass. Filed Apr. 19, 1965, Ser. No. 449,011 Claims. (Cl. 7758) The present invention is a continuation-in-part of application Ser. No. 273,160 filed April 15, 1963 and now abandoned.

This invention relates to boring holes in steel, aluminum and other metal bodies and, more particularly, the invention is concerned with an improved counterbore pilot for counterboring of the class in which a counterbore tool with a centering pilot is caused to pass all the way or a part of the way through a metal body having a previously formed pilot hole therein, whereby a thin disc or slug section is formed just before completion of the counterboring operation when boring all the way through the material.

In machine operations of this class where holes are continuously counterbored in successive workpieces, difficulty arises in connection with handling the discs or slug sections which are formed around the counterbore pilot at the end of each counterboring operation, especially when counterboring thin materials. These slug sections are of annular shape and tend to jam on the counterbore pilot. The jamming action is brought about, to a large extent, by the pressure of counterboring which may tend to force portions of relieved material against the pilot and, in some cases, pressure may cause material to roll over onto the pilot. As a result of these conditions, the slug section does not drop off the pilot readily and much production time is lost by the machine operation in dislodging the slug section from the pilot. In some cases it may even be necessary to stop the machine before the slug section can be removed.

I have discovered that this difiiculty can be completely eliminated by reaming the pilot hole in the slug section during the last part of the counterboring operation so that it is made slightly larger than its original size in diameter and hence the slug is free to drop off the pilot without interference.

As one suitable means of accomplishing this reaming operation, I have devised a counterbore pilot member with center cutting means which is located at the base of the pilot and which functions as an inner reamer member for removing small portions of the slug section immediately surrounding the pilot.

By means of this arrangement, I am enabled to increase the size of the pilot :hole in the slug section and jamming or sticking of the slug section on the pilot is overcome. Thus the slug section readily drops off from the pilot. It is also found that by enlarging the pilot hole in the slug section there is prevented any tendency for material to become rolled over onto the pilot in an undesirable manner.

The nature of the invention and its other objects and novel features will be more fully understood and appreciated from the following description of a preferred embodiment of the invention selected for purposes of illustration and shown in the accompanying drawings, in which:

FIGURE 1 is a view illustrating in cross section a W011ipiece in which a counterbore tool is shown in elevation with the improved counterbore pilot of the invention engaged in a counterboring operation;

FIGURE 2 is an end elevational view of a counterbore tool and counterbore pilot with cutters wherein the circumference of a counterbored hole is indicated at d;

FIGURE 3 is a detail elevational view of an improved 3,244,633 Patented Apr. 5, 1966 counterbore pilot member formed with slug reaming means of the invention;

FIGURE 4 is a cross section taken on the line 44 of FIGURE 3;

FIGURE 5 is a detail cross sectional view of a slug section resulting from a cut completed by an operation such as that shown in FIGURE 1; and

FIGURE 6 is a plan view of a slug section.

Referring more in detail to the drawings, FIGURE 1 illustrates diagrammatically the operation of slug reaming by the improved pilot of the invention in combination with a counterbore tool being turned through a metal body M in which a pilot hole of a desired diameter has already been formed. This illustration does not necessarily represent any particular style or make of counterbore tool. Any standard make tool of this class, including the spiral groove and the angled cutter type may be used with this improved pilot.

The counterbore tool comprises a shank portion 2 on which is supported a cutter head 4 having a plurality of cutting edges 6, 8 and 10 or more according to the style or size of counterbore used. It will be understood that the shank portion 2 is engaged in a chuck or other well known holding device forming part of a drill press or other power driving member. As is customary with counterbore tools of the class indicated, I provide in a centrally located bore 12 in the cutter head 4, a pilot element 16.

The pilot element or shank portion 16 consists of a reduced cylindrical end which is adapted to fit snugly in the bore 12 and which is formed with a flat surface 18 designed to prevent turning of the pilot in the counterbore tool as is customary with other types of pilots. At its outer end, the pilot or guide portion 20 is formed to a cylindrical shape and may be the same size as the shank portion or enlarged as shown in the drawing which part is chosen of a diameter corresponding to the diameter of the pilot hole in the metal workpiece M already formed. This improved pilot is interchangeable as is customary with other pilots.

In accordance with one preferred embodiment of the invention, I provide on the cylindrical pilot 20 at a point immediately adjacent to the relief groove 14, reamer means 22 which may, for example, consist of a conically tapered body portion formed as an integral part of the pilot and having a plurality of cutting edges as 24, 26 and 28 or more if needed to equal the number of cutting edges on the particular make or size of the counterbore tool used. The pilot cutting edges are of a size such that when the guide portion 20 is fully seated against the cutter head 4, they will project forwardly a short distance beyond the cutting edges 6, 8 and 10 of the cutter head 4.

The projecting relationship of cutting edges 24, 26 and 28 is more clearly illustrated in FIGURE 1 wherein it will be observed that the cutting edges noted are shown projected through the bottom surface of the slug section S of the metal body M at 38 while the extreme outermost portions of the cutting edges 6, 8 and 10 are just beginning to cut through the bottom of the metal body M. The cutting edges 24, 26 and 28 may also, in a preferred form, extend outwardly in an angularly disposed manner such that a slug remaining will result in a conically shaped hole.

In carrying out the counterboring operation of the invention, the tool is engaged by inserting the guide portion 20 in the pilot hole already formed in the workpiece M. Thereafter, the counterbore tool 4, through its cutting edges 6, 8 and 10 removes material to form a new hole of the overall diameter of the cutter 4 and during this period, the conical reamer 22 follows the pilot all the way through the material and enlarges the pilot hole in the slug section when the material is counterbored all the way through.

As the pilot starts to pass completely through the material, there is formed a slug section S, which is of annular shape as better shown in FIGURE 6, and which is of a tapering thickness extending radially outward from its center portion. As the pilot goes through the member M the reamer member 22 starts to cut portions of the slug section S immediately surrounding the pilot, and the original pilot hole in the slug section is slightly enlarged as at 30 (FIGURES '5 and 6). As noted therein the opening 30 has a conical shaped surface 32.

It is pointed out that as the pilot passes through the slug section, the conical reamer 22 tends to keep the tool on centerfor the last small fraction of the boring operation until the slug section 'has actually been cut away from the member M by'the cutting edges 6, 8 and it). Thereafter, the enlarged conical opening allows the slug to readily drop off from over the end of the pilot tip 2i) and the tool is "ready for the next counterboring operation.

'For counterboring part way through the material or spot facing a part size reamer on the pilot would prevent the formation of a burr at the bottom of the counterbored hole.

As noted above, the reamer means 22, may be con structed as an integral part of the pilot, especially on small to medium size pilots and may consist of angled collars which result in the formation'of a conically shaped hole. However, it should be understood that the reamer me'ans'22 is intended to be illustrative of various other arrangements, for example, an arrangement where the pilot cutters may be separately formed and fitted onto the pilot in any suitable manner or onto a shell pilot, collar or disc with cutter-tips overlapping the counterbore cutters or onto the counterbore tool in some desired manner.

While I have shown preferred forms of the invention, it will be understoodthat various other modifications may be resorted to in keeping with the spirit of the appended claims.

I claim:

1. For counterboring a sheet metal workpiece in which a pilot hole of desired diameter has already been fon'ned, a counterbore tool comprising a shank portion adapted to be received in a tool holding device,'a cutter head supported on the shank portion, a plurality of cutting edges provided on said cutter head for removing material in said counterboring of'said sheet metal workpiece, said edges projecting radially of said cutter head and defining therebetween a series of passages through which the material removed by said counterboring passes all the way through the cutter head, said cutter head formed with an axial recess defining therein a centrally located bore, a pilot for said tool, the pilot having at its rearward end a shank portion, said shank portion removably received in said bore whereby said pilot is interchangeably mounted on said tool, said bore and shank portion locked against relative rotation, a cylindrical guide portion formed at the forward end of said pilot, said forward guide portion having a smooth, non-boring surface and proportioned for a piloting fit in the pilot hole already formed in the sheet metal workpiece whereby it will guide and center said tool in said hole continuing until said counterboring is almost done, and reamer means formed on the rearward end of said pilot guide portion proximate said cutter head, said reamer means presenting cutting edges extending outwardly of said cylindrically guide portion to a diameter greater than that of'the tool shank portion and extending outwardly also of the innermost portion of said cutting edges for reaming, from the protruding slug section formed around said pilot guide portion upon the completion of said counterboring, small portions of said slug section which immediately surround the pilot, whereby to increase the size of the pilot hole in the protruding slug section, to overcome jamming or sticking of the slug section on the pilot, and to enable the slug section readily to drop off from the pilot.

2. For counterboring a sheet metal workpiece in which a pilot hole of desired diameter has already been formed, a counterbore tool comprising a shank portion adapted to be received in a tool holding device, a cutter head supported on the shank portion, a plurality of cutting edges provided on said cutter head for removing material in said counterboring of said sheet metal workpiece, said edges projecting radially of said cutter head and defining therebetween a series of passages through which the material removed by said counterboring passes all the way through the cutter head, said cutter head formed with an axial recess defining therein a centrally located bore, a pilot for said tool, the pilothaving at its rearward end a shank portion, said shank portion removably received in said bore whereby said pilot is interchangeably mounted on said tool, said bore and shank portion locked against relative rotation, a cylindrical guide portion formed at the forward end of said pilot, said forward guide portion having a smooth, non-boring surface and proportioned for a piloting fit in the pilot hole already formed in-the'sheet metal workpiece whereby it will guide and center said tool in said hole continuing until said counterboring is almost done, and a reamer member provided at't'he rear'of-said forward guide portion and adjacent to said cutter head, said reamer member presenting cutting edges extending outwardly of said cylindrical guide portion to a diameter greater than that of the tool shank portion and extending outwardly also of the innermost portion of said cutting edges for reaming, from the protruding slug section formed around said pilot guide portion upon the completion of said counterboring, smallportions of said slug section which immediately surround the pilot, whereby to increase the size of the pilot hole in the protruding slug section, to overcome jamming or sticking of the slug section on the'pilot, and to enable the slug section readily'to drop off from the pilot, and said reamer member cutting edgesextending outwardly in an angularly disposed manner so as by their reaming to produce a conically-shaped hole, whereby to keep the tool on center during the last fraction of the counterboring operation until the slug section has actually been cut away from the sheet 'metal Workpiece.

3. In a tool for counterboring a sheet metal workpiece in which the pilot hole of desired diameter has already been formed, the improvement which comprises, in combination with a tool shank portion adapted to be received in a tool holding device, a cutter head supported on the shank portion, a plurality of cutting edges, provided on said'cutter head for removing material in said counterboring from said sheet metal workpiece, said edges proiecting radially of said cutter head and defining therebetween a series of passages through which the material removed by said counterboring passes all'the way through the cutter head, said cutter head formed with an axial recess defining therein a centrally located bore, a pilot for said tool, the pilot having at its rearward end a shank portion, said shank portion removably received insaid bore whereby said pilot is interchangeably mounted on said tool, said bore and shank having means engaging to prevent their relative rotation, a cylindrical guide portion formed at the forward end of said pilot, said forward guide portion having a smooth, non-boring surface and proportioned for a piloting fit in the pilot hole already formed in the sheet metal workpiece whereby it will guide and center said tool in said hole continuing until said counterboring is almost done, and a reamer member formed on said forward guide portion, said reamer member comprising a series of center cutting means formed on the rearwardmost portion of the cylindrical surface of said guide portion and proximate said cutter head cutting edges, said reamer member cutting means extending outwardly from and to overlie at least the innermost portions of said cutter head cutting edges and being angularly dis-r posed relative to said edges such that chips cut by said reamer member will readily clear said cutting edges.

4. For counterboring a sheet metal workpiece in which a pilot hole of desired diameter has already been formed, a counterbore tool comprising a shank portion adapted to be received in a tool holding device, a cutter head supported on the shank portion, a plurality of cutting edges provided on said cutter head for removing material in said counterboring of said sheet metal workpiece, said edges projecting radially of said cutter head and defining therebetween a series of passages through which the material removed by said counterbon'ng passes all the way through the cutter head, said cutter head formed with an axial recess defining therein a centrally located bore, a pilot for said tool, the pilot having at its rearward end a shank portion, said shank portion removably received in said bore whereby said pilot is interchangeably mounted on said tool, said bore and shank portion locked against relative rotation, a cylindrical guide portion formed at the forward end of said pilot, said forward guide portion having a smooth, non-boring surface and being formed to a diameter corresponding to the diameter of the pilot hole already formed in the sheet metal workpiece and which is substantially the diameter at least of said rearward shank portion, a reamer member provided on said forward guide portion adjacent to said cutter head, said reamer member comprising a plurality of cutting elements projecting outwardly of the relatively reduced cylindrical surface of said forward guide portion and spaced by flutedefining portions of said reduced surface extending therebetween, said cutting elements reducing gradually angularly to said surface for clearance and shaped at their radial faces to present cutting edges flaring rearwardly outwardly from said surface and defining an acute angle, said flaring edges of said cutting elements functioning to remove from the slug section formed around said pilot guide portion in said counterboring, small portions of said slug section which immediately surround the pilot, whereby to slightly enlarge the original pilot hole in said workpiece and with a conical-shaped surface, to overcome jamming or sticking of the metal workpiece on the pilot, and to enable the slug section received on the pilot guide portion in said counterboring readily to drop off from said pilot.

5. In a tool for counterboring a sheet metal workpiece in which a pilot hole of desired diameter has already been formed, the improvement which comprises, in combination with a tool shank portion adapted to be received in a tool holding device, a cutter head supported on the shank portion, a plurality of cutting edges provided on said cutter head for removing material in said counterboring from said sheet metal workpiece, said edges projecting radially of said cutter head and defining therebetween a series of passages through which the material removed by said counterboring passes all the way through the cutter head, said cutter head formed with an axial recess defining therein a centrally located bore, a pilot for said tool, the pilot having at its rearward end a shank portion, said shank portion removably received in said bore whereby said pilot is interchangeably mounted on said tool, said bore and shank having means engaging to prevent their relative rotation, a cylindrical guide portion formed at the forward end of said pilot, said forward guide portion having a smooth, non-boring surface and proportioned for a piloting fit in the pilot hole already formed in the sheet metal workpiece whereby it will guide and center said tool in said hole continuing until said counterboring is almost done, different sizes of said pilot guide portion being mountable with said pilot shank portion whereby said pilot is interchangeable, and a reamer member formed on said pilot guide portion, said reamer comprising a series of center cutting means formed rearwardly around the cylindrical surface of said guide portion proximate said cutter head cutting edges, said center cutting means defining therebetween a series of passages through which chips of material cut by said means pass through the reamer member to said cutter head.

References Cited by the Examiner UNITED STATES PATENTS 2,230,645 2/1941 Jones l451l6 2,826,104 3/ 1958 Morin 7766 FOREIGN PATENTS 551,811 4/1923 France. 203,866 9/1923 Great Britain.

WILLIAM W. DYER, JR, Primary Examiner.

G. A. DOST, Assistant Examiner.

Claims (1)

1. FOR COUNTERBORING A SHEET METAL WORKPIECE IN WHICH A PILOT HOLE OF DESIRED DIAMETER HAS ALREADY BEEN FORMED, A COUNTER TOOL COMPRISING A SHANK PORTION ADAPTED TO BE RECEIVED IN A TOOL HOLDING DEVICE, A CUTTER HEAD SUPPORTED ON THE SHANK PORTION, A PLURALITY OF CUTTING EDGES PROVIDED ON SAID CUTTER HEAD FOR REMOVING MATERIAL IN SAID COUNTERBORING OF SAID SHEET METALS WORKPIECE, SAID EDGES PROJECTING RADIALLY OF SAID CUTTER HEAD AND DEFINING THEREBETWEEN A SERIES OF PASSAGES THROUGH WHICH THE MATERIAL REMOVED BY SAID COUNTERBORING PASSES ALL THE WAY THROUGH THE CUTTER HEAD, SAID CUTTER HEAD FORMED WITH AN AXIAL RECESS DEFINING THEREIN A CENTRALLY LOCATED BORE, A PILOT FOR SAID TOOL, THE PILOT HAVING AT ITS REARWARD END A SHANK PORTION, SAID SHANK PORTION REMOVABLY RECEIVED IN SAID BORE WHEREBY SAID PILOT IS INTERCHANGEABLY MOUNTED ON SAID TOOL, SAID BORE AND SHANK PORTION LOCKED AGAINST RELATIVE ROTATION, A CYLINDRICAL GUIDE PORTION FORMED AT THE FORWARD END OF SAID PILOT, SAID FORWARD GUIDE PORTION HAVING A SMOOTH, NON-BORING SURFACE AND PROPORTIONED FOR A PILOTING FIT IN THE PILOT HOLE ALREADY FORMED IN THE SHEET METAL WORKPIECE WHEREBY IT WILL GUIDE AND CENTER SAID TOOL IN SAID HOLE CONTINUING UNTIL SAID COUNTERBORING IS ALMOST DONE, AND REAMER MEANS FORMED ON THE REARWARD END OF SAID PILOT GUIDE PORTION PROXIMATE SAID CUTTER HEAD, SAID REAMER MEANS PRESENTING CUTTING EDGES EXTENDING OUTWARDLY OF SAID CYLINDRICALLY GUIDE PORTION TO A DIAMETER GREATER THAN THAT OF THE TOOL SHANK PORTION AND EXTENDING OUTWARDLY ALSO OF THE INNERMOST PORTION OF SAID CUTTING EDGES FOR REAMING, FROM THE PROTRUDING SLUG SECTION FORMED AROUND SAID PILOT GUIDE PORTION UPON THE COMPLETION OF SAID COUNTERBORING, SMALL PORTIONS OF SAID SLUG SECTION WHICH IMMEDIATELY SURROUND THE PILOT, WHEREBY TO INCREASE THE SIZE OF THE PILOT HOLE IN THE PROTRUDING SLUG SECTION, TO OVERCOME JAMMING OR STICKING OF THE SLUG SECTION ON THE PILOT, AND TO ENABLE THE SLUG SECTION READILY TO DROP OFF FROM THE PILOT.

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