US2511650A - Expanding reamer - Google Patents

Description

June 13, 1950 E. s. ROBINSON 2,511,650

EXPANDING REAMER Filed Oct. 22, 1948 351E213 Efiua- W was H ATTORNEYS Patented June 13, 1950 UNITED STATES PATENT OFFICE EXPANDING REAMER Ernest 8. Robinson, Brentwood, Md. Application October 22, 1948, Serial No. 55,929

2 Claims. 1

This invention relates to reamers and has more particular reference to reamers adapted to form undercut openings in the bottom of holes.

One object of the invention is to provide a reamer having one or more pivoted cutters adapted to be swung outwardly by a wedge member to form a irusto-conical undercut at the bottom of a hole.

Another object of the invention is to provide a reamer, as above characterized, wherein the body of the reamer is hollowed to form a housing for the wedge member.

Another object of the invention is to provide a reamer, as above characterized, wherein the cutters are readily removable for sharpening or replacement.

Another object of the invention is to provide a reamer, as above characterized, wherein the wedge member is normally held in a protracted position by resilient means.

A further object of the invention is to provide a reamer, as above characterized, which is simple and rugged in construction, economical in manufacture and eiiicient in operation.

Other objects and advantages oi the invention will appear in the following specification when considered in connection with the accompanying drawing, wherein:

Fig. 1 is a front elevational view of a reamer constructed in accordance with the present invention;

Fig. 2 is a side elevational view with parts broken away, of the reamer shown in Fig. 1, and showing the manner in which it is operated:

Fig. 3 is a partial side elevational view, similar to Fig. 2, with parts broken away, and showing the wedge member in protracted position; and

Fig. 4 is an enlarged horizontal sectional view taken on the line l4 of Fig. 1.

Referring now to the several figures hi the drawing, there is shown a reamer comprising a mandril It provided with a central chamber I I, which extends longitudinally thereof, a slidable wedge member l2, and a coiled spring I! mounted in the chamber, and a pair of cutters II, II pivotaily mounted on the mandril adjacent the open end of the chamber.

The lower portion of the mandril III is provided with an oppositely disposed pair of slots II, I I, in

which the cutter members ll, II are pivotally mounted on pins II, It extending across the respective slots It, I I. The upper end of the mandril is provided with a squared shoulder or head 2| adapted to engage the socket of any ordinary bit stock or similar boring device.

The wedge member it comprise a cylindrical stem 2! having a piston-like shoulder 22 formed on its upper end and a trusto-conical shoulder 23 formed on its lower end. The upper shoulder 22 is of less diameter than the internal diameter of the cylindrical chamber l I to permit the wedge member to freely slide therein. The frusto-conical shoulder 21 forms the wedge for engaging the inner edges of the cutters to force them outwardly.

The cutter member I is generally rectangular in outline and cross section. Its outer side wall is cut away to form a longitudinally extending cutting edge 24 and its inner side wall is provided with a longitudinally extending rounded groove 25 which normally engages the stem II of the wedge member. The cutter member Ills similar in construction to the cutter member I 4 and has an outer longitudinally extending cutting edge It and a longitudinally extending rounded groove 21 formed on its inner wall.

The bottom edges or walls of the two cutter members I4, I! are tapered downwardly and outwardly, as indicated at 28, 29, respectively, so that when the bottoms oi the cutter members engage the bottom of the hole which is being undercut, they will lie flat on the bottom of the hole, as shown in Fig. 2.

The normal position of the cutters and the wedge member is shown in Fig. 3. As there shown. the cutters are housed in their respective slots with their cutting edges even with the edges of the slot. The wedge member is protracted by the spring with the bottom edge of the upper shoulder 22 resting on the inner upper edges of the cutter members. In this position the spring II is not tensioned.

The coiled spring II is loosely mounted in the upper end of the chamber II with its top end engaging the top of the chamber and with its bottom end engaging the top end of the shoulder 22 of the wedge member I2. The spring normally holds the wedge member in a protracted position with the bottom edge oi the shoulder 22 engaging the top inneredges of the cutter members.

It will be noted that the cutter members extend well below the bottom oi the mandril (see Figs. 1, 2 and 3). This allows the shavings or chips created by the reaming process to collect between the exposed ends of the cutter members at the bottom of the hole. In addition, a pair of elongated rounded recesses 30, ll are formed on the outer surface of the mandril, each posi- 3 tioned circumferentially in front of the cutting edges of the cutter members.

The manner in which the reamer is operated is believed to be obvious. It is inserted in a prebored hole in a piece of wood or other suitable material, the hole being of slightly larger diameter than the diameter of the reamer, until the bottom of the wedge member rests in the bottom of the hole. As pressure is applied on the mandril with the reamer rotating, the cutter members will be forced increasingly outward to form a frusto-conical undercut extending upwardly from the bottom of the hole. This is illustrated in Fig. 2, where there is shown in cross section a block of wood 32 having three semi-cylindrical holes I3, 34 and 35 formed therein. The hole 33 has not been undercut, the hole 34 has been undercut, while the reamer is shown (partly in cross section) in hole 35 completing an undercut therein.

From the foregoing, it readily will be seen that there has been provided a reamer for forming undercuts in the bottom of holes which is simple and rugged in construction, economical in manufacture, and eflicient in operation, and having cut-' ters which may readily be removed for sharpening or replacement.

What is claimed is:

1. An expanding reamer for forming a frustoconical undercut at the bottom of a bored hole comprising a cylindrical mandrel adapted to be inserted in the hole and having a cylindrical axial bore extending through its lower end, and terminating short of its upper end; the lower end por- 4' tion of the mandrel having longitudinally extending and circumferentially spaced, radial slots; longitudinally extending cuttingblades pivotally mounted at their upper.ends in said slots and projecting below the lower end of said mandrel with their upper inner end portions extending slightly into the bore; a frusto-conical wedge member coacting with the inner edges of said blades and having a stem projecting into said bore; a piston-like shoulder member on the upper end of said stem slidably mounted in said bore and confined therein by the inwardly projecting upper ends of said blades; a compression coil spring loosely mounted in the bore and abutting the upper end of said piston-like shoulder normally projecting the frusto-conical wedge below the lower ends of said blades.

2. An expanding reamer, as set forth in claim 1,

wherein the mandrel has longitudinally extendins recesses in" its outer wall in front of the cutting edges of the blades to receive shavings.

ERI IEST S. ROBINSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 752,724 Taylor Feb, 23, 1904 762,458 Willard June 14, 1904 833,240 Potter Oct. 16, 1906 2,214,484 Seal Sept. 10, 1940 2,401,074 Huelster May 28, 1946

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