US2577986A

US2577986A - Expansion bit

Info

Publication number: US2577986A
Application number: US677486A
Authority: US
Inventors: Harry C Wilson
Original assignee: ROBERT H CLARK
Current assignee: ROBERT H CLARK
Priority date: 1946-06-18
Filing date: 1946-06-18
Publication date: 1951-12-11
Anticipated expiration: 1968-12-11

Description

Dec. 11, 1951 c w 2,577,986

EXPANSION BIT Filed June 18, 1946 2 SHEETS-SHEET l I N VENTOR ATTORNEY H. C. WILSON EXPANSION BIT Dec. 1l, l951 2 SHEETS-SHEET 2 Filed June 18, 1946 ATTORNEY Patented Dec. 11, 1951 2,577,986 EXPANSION .311

Harry 0. Wilson Sherman Oaks, Califl, assignor 'to Robert H. Clark, Los Angeles, Calif.

Application June 18, 1946, Serial No. 677,486

8 Claims. (01. 145'127) This invention has to do with a bit and it .is more particularly concerned with an adjustable bit of the type commonly known as an expansion bit. A general object of the present invention is to provide an improved, simplified and inexpensive construction for expansion bits.

The present invention is concerned primarily with improvements in an expansion bit such as is the subject of my copending application entitled Expansion Bit, Serial No. 566,838, new Patent No. 2,496,427, filed December 6, 1944.

It is an object of my present invention to provide a simplified and improved clamp plate in an expansion bit of the character referred to which plate serves to .hold the cutter to the body and is itself formed with a cutting lip and a marginal spur which parts cooperate in cutting the central portion of the bore. An outstanding feature of the clamp plate that I have provided is that it is a thin, light part that minimizes the obstruction to the free flow of cuttings and which is easily and inexpensively manufactured.

It is a further object of my present invention to provide an improved, highly efiicient cutter for an expansion bit. By my present invention I provide a cutter which is an elongate part clamped between the body and the clamp plate to have a projecting portionthat cuts, which cutter is formed of sheet metaland has a bent or deflected outer end portion with a cutting blade disposed to cut at a most advantageous angle.

The various objects and features of my invention will be fully understood from the following detailed description of a typical preferred form and application of my invention, throughout which description reference is made to the accompanying drawings, in which:

Fig. 1 is a view showing the bit of the present invention in a typical brace by which it may be operated. Fig. 2 is an enlarged view of the working or lower end portion of the bit, being an enlargement of a partof Fig. 1. Fig.3 is a plan section taken as indicated by line 3--3 on Fig. 2. Fig. 4 is a perspective view of the clamp .plate of the present invention showing it disposed in .a substantially horizontal plane and showing it viewed from its upper side to illustrate the .manner in which it is shaped. Fig. '5 is a perspective view of the cutter that Lhaveprovided being a view showing the forward or leading :side of the cutter. Fig. 6 is a bottom plan view of the tool, being a view taken as indicated byline 6 -6 on Fig. 2. Fig. 7 is a side elevation :of the bit taken as indicated by line 1-'! :on Fig. 3. Fig. 8 is a side elevation of the bit .takenasindicated by line 8-8 'on Fig. 2. Fig. 9 is a vertical sectional view taken as indicated by line 9-9 on Fig. 8 showing the construction at the center of the bit and Fig. 10 is a sectional view taken as indicated by line l0-l 0 on Fig. 9.

The bit'of the present invention is particularly useful for drilling holes in wood or the like-and in Fig. 1 of the drawings I have shown it in a typical brace such as is commonly employed for operating a bit or drill, and inFig. 7 I have shown it in process of drilli g a hole through a board B. 1

The bit involves, generally, a body ill, means II for mounting the body in a machine or operating tool, a'main cutter l2, means 13 for mounting the cutter on the body so thatit projects downwardly and outwardly therefrom, a leador feed screw l4 projecting from the lower end of the body and a core cutter I5 on the lower end of the body.

The body in its preferred form is an elongate block of metal such as steel, having anouterside which is round or turned to be concentric with the longitudinal axis of the bit. The upper end 2! of the body is pitched to extend upwardly and inwardly at an angle. The lower end 22 of the body is preferably a fiat part or surface disposed in a plane pitched at a substantial angle relative to the axis .ofthe bit or relative to a plane normal to the axisof the bit. In the case illustrated the bottom 22 is pitched at an angle of about to a plane normal tothe axis of the bit. One side of the body is cut awayso that the body has a fiat side 23 extending parallelwith the axis of the bit. The cut in the side of the body is'made deep so that there is .a substantial opening or clearance at the side of the body-at or adjacent the face 23 to accommodate chips or cuttings.

The body has a central longitudinal opening formed through it. The upper end portion .24 of the opening is somewhat larger than the lower end portion so that the opening receives or accommodates parts of different diameters as will be hereinafterdescribed.

The means Ll provided for mounting-thebody A 3 stem with a finished lower end portion 28 which fits tightly into the upper end portion 24 of the body opening. The stem in this case has an extension 29 of reduced diameter fitting the small or reduced lower portion 25 of the body opening. The extension 29 projects below the lower end of the body to form the lead screw l4. Where the stem and body are formed separately as just described they may be secured together in any suitable manner. For instance, it is practical and economical to sweat them together with silver solder so that they, in effect, form a solid unit.

The cutter i2 is an elongate blade-carrying part carried by the body In to project downwardly and outwardly therefrom. The mounting means I3 serves to hold the cutter in position so that it is rigidly or firmly held in the desired position of adjustment relative to the body. In accordance with my present invention the cutter I2 is formed of a plate or sheet of metal and it has a shank portion 30 shaped or formed to be V-shaped or channel-shaped incross sectional configuration and it has an outer active or tip portion 3| that projects from the body and which is dressed to have a forwardly facing cutting edge 32 and which is provided at its outermost end with a downwardly projecting lip or spur 33.

A cutter carrying channel 35 is provided in the bottom face 22 of the body l0 and the means I3 clamps the shank of the cutter in the channel 35. With my improved construction the shank 30 being V-shaped in cross sectional configuration has spaced or diverging flange-like side parts X and Y. The channel 35 in the body I0 is formed so that it is V-shaped and receives the shank of the cutter so that the side Y thereof bears against one side of the channel while the side X is substantially parallel with the bottom 22 of the body and so that the outer edges 36 of the side X and Y respectively are in bearing engagement with the other side of the channel.

The cutter is arranged in the channel in the manner above described so that the edge 36 of side X of the cutter faces in the direction that the cutter operates or is such as to advance and form a leading edge as the cutter is operated. The tip portion of the cutter is a highly important feature of the present invention since it is bent or turned back at a point outward of the body In in a direction opposite to that in which the cutter moves into the work so that the side Y which continues from the shank portion to and along the tip portion, instead of extending straight out from the body, extends out and then rearwardly relative to the direction of rotation of the body. The projecting portion of the side X is dressed to present the sharp or keen cutting edge 32, it being preferred to form this edge by grinding or otherwise dressing the side part X of the cutter at both its upper end lower sides. The side Y of the cutter continues from the shank portion to the tip portion where it gradually dies out or'diminishes in vertical extent until it terminates at the outermost end of the cutter. As the strip of material out of which the cutter is formed is shaped or bent to gain the tip construction just referred to the side X of the cutter widens somewhat as it approaches the extreme outer end of the cutter, thus presenting ample stock behind the cutting edge so that the cutter can be repeatedly sharpened. The extreme outer end of the cutter, that is, the tip portion thereof, is merely bent down so that the spur 33 depends from the outer end of the 4 side X of the cutter. It is to be understood that the spur can be pitched to give it proper clearance and that it can be sharpened or dressed so that it presents a. sharp leading or cutting edge 33.

It is to be observed from the drawings and it will be apparent from Figs. 3 and S of the drawings, how the cutting edge 32 presented by the cutter is at the forward leading portion of the side X as the cutter is rotated to advance into the work and it will be noted that the edge 32 instead of being a simple straight cutting edge has a straight portion a projecting substantially radially from the body while the main cutting portion 1) of the edge is joined to the part a by a suitably curved part and then projects outwardly and rearwardly relative to the direction of rotation of the tool. The extent of the edge portion a will vary depending upon the setting of the tool and unless the cutter is set to extend or project a substantial distance from the body the blade portion a will be entirely within the channel within the body so that the pitched portion 11 of the blade is the only part that is active or which projects to cut. By pitching the main cutting portion b of the cutting edge outwardly and rearwardly the cutter has a desirable efficient shearing action that will cut wood by making acurl or shaving rather than acting to bite into the wood to tear or remove it in chunks.

In practice it is desirable to provide the cutter with means by which the user may determine the extent to which it is projecting from the body. This may be done by providing a scale on one side or face of the cutter, preferably the side Y, to cooperate with the end edge 8| that occurs where the channel 35 intersects the curved exterior 20 of the body, which edge may be straightened for the purpose of proper cooperation with the scale.

The means l3 for mounting the cutter involves the channel 35 provided in the bottom 22 of the body, as described, a clamp plate 44 arranged at the lower end of the body to engage the outer or under side of the cutter side X as clearly shown in Figs. 2, 7, 8, 9 and 10 of the drawings, and a screw 10 retaining the plate. The channel above described is preferably formed immediately adjacent the extension of the stem 23 in which case it is slightly offset from the center of the tool and it extends in the direction that the bottom 22 is pitched downwardly relative to the axis of the tool so that it carries the cutter with the top portion thereof outward of and below the lower end of the body opposite the lowermost portion of the body. Further, it will be apparent from the drawings that the channel is made deep enough to all but completely receive the shank of the cutter, with the result that a portion of the side X of the cutter shank projects slightly beyond or below the bottom 22 of the body to be engaged by the plate 44. The clamp plate 44 is, in accordance with my present invention, a fiat plate or body of sheet metal that can be stamped punched, or otherwise formed into the desired shape and in its preferred form it has, an outer curved surface 45 concentric with the axis of the bit and of the same size and curvature as the outer size 20 of the body ID. The top side or face 46 of the clamp plate opposes the end 22 of the body to be parallel therewith or substantially parallel therewith while the lower side or bottom 41 is parallel with the top side 46. The plate 44 has a central round opening 48 that passes the extension 29 of the stem 26; the round opening being located to'pass the extension ofthe stem which is concentric with the central axis of the bit and with the outer curved surface d5 of the plate.

In accordance with my invention I provide the plate M with a cutting lip 50 and a depending spur 5| which forms the core cutter l5. To form or establish the lip 55.! a cut is made in the clamp plate from its outer curved surface to the central opening ts and the portion of th plate at one side or defining one side of the cut is deflected or bent down so that it forms the lip which is defiected somewhat downward from the lower side or bottom 4? of the plate. The lip 58 faces in the direction that the tool turns or in the same direction as the cutting edge 32 and it is dressed away at 52 to establish a forward cutting edge 55. The out just referred to is made in the plate 4.6 so that it occurs at the fiat. side 23 of the body H! with the result that the lip 50 projects from the flat side of the body as will be seen in Figs. 3 and 8 of the drawings, so that there is clearance or space above the lip to accommodate cuttings or chips made by the edge 55. At the other side of the cut, that is, forward of the lip 50, the plate is cut away as by dressing away the plate so that it has a flat edge 60 coinciding with the fiat side 23 of the body, which fiat sided portion has its lower side bevelled away at El to further provide chip clearance.

The spur of the core cutting means I 5, that is, the spur 5| on the plate 4-! is formed or established by making a transverse fiat cut 65 at the lowermost portion of the plate, which cut is made to come close to the very edge of the lowermost part of the plate but is spaced from it enough to leave the depending spur as shown in Figs. 2, 7 and 9 of the drawings. By forming the spur at the lowermost portion of the plate and by doing so by means of a simple machine cut across the bottom of the plate, I am able to form an effective spur or core cutting projection as a part of or integral with the simple sheet metal plate without resorting to expensive forming or drawings operations such as are ordinarily required in the formation of such a part. It is to i be observed that the spur 5|, being located at the lowermost point of the plate 44, occurs at the lowermost part of the body I from which the main cutter projects so that the spur occurs adjacent the cutting edge 32 and it is to be observed that the spur is located about 90 around the periphery of the plate 44 from the cutting edge 55 of the lip. By locating the spur ad- J'acent the edge 32 of the main cutter to cut slightly forward thereof, as shown throughout the drawings, the spur serves to make a out between the surfaces cut by the edges 55 and 32 With the result that the cutter as a whole cuts through a body of wood or the like making two distinct chips or curls as it operates.

The means It includes, in addition to the plate 44, a screw 70 which extends through the body downwardly at an angle from the upper end portion thereof to project from the bottom face 22 and thread into an opening H provided in the plate. A bore '52 is provided in the body to extend from the beveled upper end thereof diagonally downward in a direction normal to the bottom end face 22 and intersecting the central axis of the bit, and thus passing through the tool the bore 12 passes through the body and also through a portion of the stem and its extension, as will be seen in Fig. 9. The screw has a head 14 at the upper end of the body and its lower end is provided with a thread to engage in the threaded opening II .in'the plate 44. It will be apparent that as th screwis tightened the plate is drawn toward the face .22 of the body so that it clamps or -,bears .against the side X of the cutter clamping th cutter tightly in the channel in the body. The'feed screw I4 is formed by continuing the projection 29 beyond the lower end of the body and thevprojecting portion of the extension is tapered and threaded while the extreme tip end is flattened or made somewhat diamond shaped as shown in the drawings.

From the foregoing description and from the drawings it will beobserved that I have provided a cutter that projects from the body I ii and which has a simply formed yet highly effective cutting edge arranged at a most advantageous angle. The cutter is formed of sheet metal and is carried in thechannel of the body so that'the side X of the cutterlies substantially in theplane of cut of the edge 32, and it is readily dressed back from the edge to present a thin sharp cutting part that will out wood in a most eflicient manner and far better than will a cutter that is blunt and does not present a sharp chisel-like edge. It is also to be observed that by forming the cutter of sheet metal it can be readily turned back so that its tip portion extends ata most advantageous angle and likewise it can be readily bent down at its extreme outer end to form the spur 33.

.It will also be apparent from the present disclosure that the plate 44 that I have provided not only serves as a simple, effective means of holding the cutter in engagement with the body but it is also easily formed from a plate or body of sheet metal andcan be readily worked or shaped to present the lip and the spur 5|. In manufacture the plate that I have provided can be made easily and quickly and in operation it cuts in a most satisfactory manner, serving to cut a core or central opening from the extension of the shank outward to the point where the main cutter starts to cut. The extent to which the main cutter cuts or, that is, the size of the hole made by the bit, will be deiermined by. the adjustment of the main cutter or, in other words, by the amount of the main cutter that projects outward beyond the wall 29 of the body.

Having described only a typical preferred form and application of my invention, I do not wish to be limited or resLricted to the specific details herein set forth, but wish to reserve to myself any variation or modifications that may appear to those skilled in the art and fall within the scope of the following claims:

Having described my invention, I claim:

1. A bit of the character described including, a central body with a lower end face in a plane inclined to a plane normal to the axis of the bit, there being a downwardly opening channel in the lower end face of the body, a cutter carried in the channel to project from one side of the body and to a point below the lower end of thebody, a plate opposing said lower end face and retainin the cutter in the channel, and means securing the plate to the body, the cutter being V-shaped in cross section and having its projecting portion turned back from the direction of cut.

2. A bit of the character described including, a stem, a fixed rigid central body on the lower end of the stem and having a, channel in its lower end, a cutter carried in the channel to project from one side of the body and to a point below the lower end of the body, a plate retaining the cutter in the channel, means securing the plate to the body, the cutter being V-shaped in cross section and having its projecting portion turned back from the direction of cut, the leading longitudinal edge of the cutter being sharpened to cut, the plate being a sheet metal disc notched from the edge and pro jecting down adjacent the notch to form a forwardly facing lip with a sharpened forward edge.

3. A bit of the character described including, a central stem, a central body permanently fixed on the lower end of the stem to be rigid therewith and having a channel in its lower end, a cutter carried in the channel to project from one side of the body and to a point below the lower end of the body, a plate separate from the body and stem and opposing the lower end of the body to retain the cutter in the channel, means securing the plate to the body, the plate being a sheet metal disc notched from the edge and depending down adjacent the notch to form a depending forwardly facing lip with a sharpened forward edge.

4. A cutter for an expansion bit including a continuous strip of sheet metal having a shank portion uniformly V-shaped in cross section throughout its length, there being a tip portion projecting from the shank portion and widening as it projects from the shank portion, the leading edge of the tip portion being sharpened.

5. A cutter for an expansion bit including, a strip of sheet metal having a straight elongate shank portion V-shaped in cross section throughout its length to have substantially equal side portions with the outer edge of one side portion sharpened, the strip having a tip portion extending from the shank portion at anangle thereto with a sharpened edge continuous with the sharpened end of the shank portion.

6. A cutter for an expansion bit including, a strip of sheet metal having a straight elongate shank portion V-shaped in cross section throughout its length to have substantially equal side portions with the outer edge of one side portion sharpened, the strip having a tip portion extending from the shank portion at an angle thereto with a sharpened edge continuous with the sharpened end of the shank portion and forming an obtuse angle therewith, the tip portion fiattening and becoming wider than the shank portion as it projects therefrom,

7. A cutter holding clamp for an expansion bit including a substantially round sheet metal plate with a central screw passing opening and an eccentric retainer receiving opening and having a notch-like opening extending into it from its peripheral edge, the notch-like opening having side edges that extend in from the periphery of the plate, the plate having a portion adjacent one of the edges of the notch-like opening projecting below the bottom side of the plate and being sharpened forming a cutting lip.

8. A cutter holding'clamp for an expansion bit including a substantially round sheet metal plate with a central screw passing opening and also having a threaded retainer receiving opening eccentric to the central opening. there being a notch in the plate from the edge and communicating with the central opening, one side edge of the notch being offset downwardly from the plane of the plate and sharpened forming a cutting lip.

HARRY C. WILSON.

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

UNITED STATES PATENTS Number Name Date 567,977 Hagerty Sept. 22, 1896 843,832 Lingol Feb. 12, 1907 916,527 Beugler Mar. 3 1909 1,056,670 Hayden Mar. 18, 1913 1,283,414 Kitchen Oct. 29, 1918 1,576,676 Ruble Mar. 16, 1926 1,585,000 Thomson May 18, 1926 FOREIGN PATENTS Number Country Date 533,808 Germany Sept. 18, 1931