US1807998A - Reversible self-sharpening chisel - Google Patents

Description

June 2, 1931.

J. l. M CORD REVERSIBLE SELF SHARPENING CHISEL Filed Dec. 26, 1929 v INVENTOR cfohn I.M== Cord BY M .QQJJQ;

ATTORNEY Patented a... 2, 1931 UNITED STATES;

JOEN' I. HOODED, 01 P550 ROBLES, CALIFORNIA, ASSIGNOB OI ONE-FOURTH 1'0 BAY IB- LYON, OI PASO ROBLES, CALIFORNIA Y mn'asmnn snnr-snnnrnme cmsnn Application filed December 26, 1929. Serial No. 416,481.

This invention relates to ground workin implements, and particularly to the chise points adapted for use on sub-soilers, road plows and chisel cultivators, my improved 5 point being particularly useful where dry work is necessary or hard ground must be penetrated.

All such chisels as are now in use as far as I am aware are constructed in such a manner that as soon as the cutting edge becomes dull and wears down the chisel has a decided tendency to work out of the ground, and of course does not then function as it should. This condition is reached so quickly that chisels cannot be used without being resharpened for even one hour of continuous work. The labor and overhead costs due to the continuous resharpening and refitting operations necessary, and the consequent tie-up of the machine, are therefore considerable.

The rincipal object of my invention is to avoid t e above very objectionable features by so shapingl the chisel as to cause the same 5 to proper y old inthe ground for a long time as compared to the chisel, and so .that when t becomes dull and the point resent type of e cutting edge has been worn back, reversing of the chisel changes this dull edge into a sharp one. This last edge in turn becomes dull in time and upon again reversing the chisel or returning the same to its original position a sharp point is again pressed into the groun My im roved chisel can therefore be efiicientl use until the available wearing portion 0 the same is entirely worn away, wlthout any manual resharpening or other attention being necessa except to reverse the setting of the chisel v4o when required.

'To enable this reversing of the chisel to be easily carried out I haveprovided what I believe is a novel and automatic but easily releasable locking connection between the chisel and its supporting standard.

A further object of the invention isto r0- vide a simple and inexpensive device an yet one which will be exceedi ly effective for "the purpose for which it isl gesigned.

These objects I accomplish by means of such structure and relative arrangement of parts .as will fully appear by a erusal of the following specificatlon and claims.

In the drawings similar characters of reference indicate corresponding parts inthe several views:

Fig. 1 is a perspective view of my improved chise Fig. 2 is a side elevation of the chisel in its normal ground engaging position and before any wear has taken lace.

Fig. 3 1s a similar view s owing the chisel as somewhat worn awa and the cutting edge dulled from continue use in said original position.

Fig. 4 is a similar view of the chisel part1 in section showing the chisel as in the combtion illustrated in Fig. 3 but reversed in positionrelative to the ground.

Fig. 5 is a fragmentary longitudinal plan PATEN errea 7 section of the chisel showlng the locking con- I chisel-may be considered as constituting a relatively thick base portion 1 and a relatively thin point portion 2; said portions being however the same width in a transverse plane from end to end as shown in Fig. .1. The base portion is provided with a tapered socket 3 into which removably fits a similarly shaped tongue 4 which projects with a slight downward angle from the supporting standard 5 of any suitable character. This tongue is disposed so that the chisel will extend toward the ground at a relatively small slope or angle and is symmetrical in form relative to its longitudinal axis so that v the chisel will havesubstantially the same slope whether in its normal or reversed position. The chisel is reinovably locked on' the tongue by a special device which will be 7 7 full described later.

T e trouble w1th the ordinary chlsel points is that there is so much friction underneath the same that the oint is forced out of the ground as. soon as .t e initial chisel or wedgeshaped cutting edge A. becomes dulled and practically reversed as to its angular relation to theground. I

This objectionable feature I have entirely eliminated by forming the under side of the point portion, for substantially the full length of the same, with a curvature B which 1s concave relative to a straight line G extending between the bottom of the base and the bottom of the point at the ti or edge A; said curved portion bein entire y above said line. On the upper surface of the chisel on the other hand the point portion is formed with a convex curve D, extending rearwardly from the cutting edge a certain distance, and then with a reversed or concave curve or fiat bend E. The convex curve D is mainly above and the :bend or concave curve E is below, a straight line F drawn from the top of the edge A to the back of the base at the top. Thisarrangement or shape of the upper and lower contours of the chisel is what gives my improved chisel its advantages over the ordinary form ofchisel. By reason of the concave curvature of the under surface of the point portion, there is no material friction on the under side of the chisel in operation such as would tend to raise the point and cutting edge out of the ground. This in turn keeps all the weight of the chisel on the cutting edge, and this remains true as the edge wears back along the point, owing to the length of said concave curvature. The holding of the point in the proper digging position in the ground is aided by the raised or convex top curvature D, whose frictional contact with the ground tends to causethe forward portion of the chisel to be depressed. Also, this raised tortion being sub ected to a relatively great friction, it wears down as the cutting edge wears back. Therefore by the time the chisel has worn back until the setting of the cutting edge relative to the ground is substantially parallel to the ground, as shown at H, the height or thickness of the chisel at that point has also been reduced a certain amount, so that the thickness of the chisel at the cutting edge wherever this may be, is maintained substantially constant.

The bend. or curve E- serves two ends. The

- upper surface of the chisel havin a downward slope from the base towar the cut-' ting edge, relative to the direct. line F between the ends of the chisel, enables the oint portion of the chisel. to enter the groun at a flatter angle as is desired, while maintainin .thedesired convex curvature at the front on of the chisel, than would otherwise be ossible. Also when the chisel is reverse position this'curve or bend E takes the place of and serves the same purpose as does the curve or undercut B when the chisel is disposed in its normal position. This .will be A evident from a' comparison of Fig. .4 (the chisel when reversed) with Fig. 2 (the chisel in its normal position) The point of major depression of the bend E is disposed some curve B. Thus when the chisel is worn down considerably or as far is the edge '11, and the chisel is then reversed, said bend E occupies approximately the same position relative to the newcutting edge H as the curve B occupies relative to the original cutting edge A. The chisel is preferably maintained in its reverse position only long enough to reverse the angle of the cutting edge to one having the same relative setting to the chisel as that originally provided. Upon this condition being reached the chisel is again returned to its original or normal position.

The means for locking the tongue to the chisel is constructed as follows:

Extending lengthwise of and'disposed in a recess 6 formed in one side of the tongue is a flat spring 7 ,secured to the tongue at the end nearest the outer end of the same and normally projecting outwardly from the recess at its opposite or free end, as shown in Fig. 5,

The free end of the sprin is adapted to project into either one of t e opposed recesses 8 formed in the sides of the socket-3,

pressed until it reaches the corresponding. end of the recess 8 wlfen'it will snap out into said recess, and will thus prevent withdrawing movement of the hisel from the tongue.

Such withdrawal ho ever can be easily accomplished when desired by de ressing the sprin by' means of a nail or ot or tool inserted through the corresponding hole 9 and holding the spring depressed while the is drawn outwardly suflicient to move the free end of the spring beyond the adjacent end of the socket recess.

From the foregoing description it will be readily seen that I have fiproduced such a device as substantially ful Is the objects of the invention as set forth herein. I While this specification sets forth in detail the present and preferred construction of the device, still in practice such deviations from such detail may be resorted to as do not form a de arture from the spirit of the invention, as efined by the appended claims. Having thus described my invention what I- claim as new and useful and desire to secure by Letters Patent is:

1. A chisel for ground working implements chisel p comprising a base portion adapted for attachment to a standard and a oint portion having a transversely exten ng cutting edge;

said point portion having its under surface" concavely curved from the cutting edge rearwardly acertain distance, and having its upper surface formed with a convex curvature comprising a base portion adapted for attachment to a standard and a point portion having a transversely extending cutting edge; sald point portion having its under surface 5 concavely curved from the cutting edge rearwardly a certain distance, and having its upper surface formed with a convex curvatureextending rearwardly from the cutting edge, said convex curvature merging into a concave curve disposed some distance rearwardly of the plane of the concave curvature on the under side of the point.

3. A chisel for ground working im lements comprising a base rtion adapte for at- 15 tachment to a stan ard and a point portion having a transversel extending cutting edge; said point portion aving its under surface concavely curved from thecutting edge rearwardly a certain distance, and having its up- 20 per surface formed with a convex curvature extending rearwardly from the cuttingedge, said convex curvature mergin into a concave curve disposed entirely be ow a straight line projected from the cutting edge to the 25 rear end ofthebase at theto In testimony whereof I a x m si ature,

J CH3 1. 0C RD.

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