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Publication numberUS3336081 A
Publication typeGrant
Publication dateAug 15, 1967
Filing dateAug 2, 1965
Priority dateAug 2, 1965
Publication numberUS 3336081 A, US 3336081A, US-A-3336081, US3336081 A, US3336081A
InventorsEricsson Samuel S
Original AssigneeEricsson Samuel S
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Percussion tool with replaceable point
US 3336081 A
Abstract  available in
Previous page
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Claims  available in
Description  (OCR text may contain errors)

Aug. 15, 1967 5.5. ERICSSON PERCUSSION TOOL WITH REPLACEABLE POINT Filed Aug. 2, 1965 SAMUEL $1 ER/CSSON N VE /V T 0/? BUCKHOR/V, BLORE, KLAROU/ST a SPAR/(MAN ATTORNEYS United States Patent 3,336,081 PERCUSSION TOOL WITH REPLACEABLE POINT Samuel S. Ericsson, Lake Oswego, Oreg. (3320 SE. 50th Ave., Portland, Oreg. 97206) Filed Aug. 2, 1965, Ser. No. 476,480 1 Claim. (Cl. 299-91) ABSTRACT OF THE DISCLOSURE This invention relates to impact or percussion-driven tools such as are used with pneumatically or electrically powered hammers for breaking up pavement, concrete and other hard materials and, more particularly, to such a tool having a replaceable point.

Percussion tools have been available with replaceable points. One such tool is disclosed in Coski Patent No. 3,027,953. Such tools have been formed, however, with a replaceable point having a maximum diameter greater than the diameter of the shank. A replaceable point so constructed will often catch on the concrete or pavement being broken up, thereby to become separated from the shank or otherwise to cause the operator inconvenience and trouble.

It is thus an object of the present invention to provide a percussion tool having a replaceable point that will not come 01f in use.

It is a further object of the present invention to provide such a tool with a replaceable point that can be loosened and replaced quickly and easily, when desired by the operator.

' The percussion tool of the present invention has a shank and a replaceable sharpened point. The shank, however, instead of being of constant cross section, gradually increases in diameter toward the end which is adapted to receive the sharpened point. This enlarged diameter forms a shoulder near the end of the shank, and the shank thereafter tapers inwardly from the shoulder. The sharpened point has a corresponding inwardly recessed tapered surface, so that it can engage with the tapered surface on the shank. By virtue of the shoulder formed on the shank, the maximum diameter of the sharpened point is substantially equal to the maximum diameter of the shank. Thus, I have minimized the possibility of the sharpened point catching on the work, or otherwise causing trouble by reason of a lateral protrusion.

It has been found that if the shank is tapered at an angle of about degrees with respect to its longitudinal axis, the impact of the percussion force is transmitted satisfactorily to the sharpened point, yet the latter is easily and quickly removed from the shank whenever necessary. The inwardly recessed surface of the sharpened point is also desirably made to taper at an angle of about 5 degrees with respect to the longitudinal axis of the tool, thereby to correspond with the taper on the shank.

Other features and advantages of the present invention will become apparent from the following description of a typical embodiment, wherein like numerals refer to like parts, and wherein;

FIG. 1 is an exploded perspective view of the percussion tool of the present invention showing the shank and sharpened point disassembled;

FIG. 2 is an exploded side view of the work-entering end of the tool shown in FIG. 1 with parts disassembled, and with the sharpened point shown partly in section; and

FIG. 3 is a side view of the work entering end of the tool showing the parts assembled together.

Referring to the drawings, the percussion tool 10 of the invention has a shank 11, the upper end 12 of which is adapted to be held in the jaws of a pneumatically or electrically powered hammer (not shown). The end 12 is formed to fit the jaws of the hammer. As shown it has a hexagonal shape, although it may be of any suitable shape to engage in the hammer, and terminates in a collar 13. Between the collar 13 and the end 20 of the shank adapted to receive the sharpened point, the shank has a body portion 14 of circular cross-section, as shown. The cross-section of the body portion 14 is of constant diameter for a portion of the length of the shank from the collar 13, but thereafter gradually increases in diameter to a shoulder 15 of maximum diameter adjacent the point receiving end 20. For example, if the body portion 14 of the shank has a diameter of 1% inches in its constant diameter portion, such diameter may be enlarged to 1 inches at the shoulder 15. The diameter of the shank is thereafter sharply reduced to form a neck 16, joining the end 20 and shoulder 15.

The point receiving end 20 is formed with a frustoconical surface 21 that preferably defines a small acute, included angle of about 5 degrees with respect to the longitudinal axis AA of the shank. The inwardly tapered surface 21 of the shank is shown terminating in a blunt surface 22, which is perpendicular to the longitudinal axis AA, although the surface 22 could be rounded if desired.

A sharpened point 25 is adapted to fit on the tapered surface 21 of the shank 11. The point 25 has an outer diameter at its upper end substantially equal to the diameter of the shoulder 15 and is formed with an opening 26 defined in part by a frusto-conical wall 27, which has a complementary taper of about 5 degrees also with respect to the longitudinal axis A-A of the tool. The open ing 26 in the point 25 terminates in a convex curved surface 30.

The opening 26 and shank end 20 are so dimensioned that the shank end 20 is received within the opening 26 without bottoming out, which is important, of course, both from the standpoint of transmitting forces from the shank to the point and also in retaining the point upon the shank. In this regard, it should be noted that the -5 degree taper permits the percussive force to be transmitted by the shank to the point, yet the point can be easily and quickly removed from the shank as desired. The wall 27 is made sufiiciently thick to withstand the forces expected in use. The point terminates in a conventional sharpened cutting point 29.

When the sharpened point 25 is placed in position on the tapered end of the shank 11 and interfittingly engages therewith, it will be seen from FIG. 3 that the upper end of the wall 28 of the point 25 does not protrude laterally of the shank, and there is a minimum of likelihood of the point catching on the Work.

The shank and point 25 may be formed of any suitable steel, capable of being normalized and heat-treated to a suitable hardness.

In the foregoing description, the invention has been described with reference to a certain particular embodiment, although it is to be understood that the specific details shown are merely illustrative and that the invention may be carried out in other ways without departing from the true spirit and scope of the appended claim.

I claim:

A replaceable point type of percussion tool, comprismg:

3 a sharpened point and a shank,

said shank having one end adapted to be struck, the other end being adapted to receive said sharpened point, said shank gradually increasing in diameter from said one end toward said other end to provide a shoulder of maximum diameter intermediate said ends; said shank tapering inwardly from said shoulder to said other end at a small acute angle with the longitudinal axis of said shank to define thereby a point engaging portion, said sharpened point having an opening having an inwardly recessed frusto-conical surface tapering at a complementary angle to said small acute angle and terminating in a convex curved surface, said point 4. engaging portion of said shank and said opening in said sharpened point being so dimensioned that said opening receives said shank without permitting said shank to bottom in said opening, the maximum diameter of said sharpened point being substantially equal to the maximum diameter of said shoulder on said shank.

References Cited UNITED STATES PATENTS 2,454,771 11/1948 Carr 175419 FOREIGN PATENTS 867,381 2/1953 Germany.

ERNEST R. PURSER, Primary Examiner.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US2454771 *May 8, 1944Nov 30, 1948Sarah Jane CarrDrill bit assembly
DE867381C *Nov 10, 1951Feb 16, 1953Wilhelm KarnebogenSpitzeisen fuer Abbauhaemmer
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3655244 *Jul 30, 1970Apr 11, 1972Int Tool SalesImpact driven tool with replaceable cutting point
US4007795 *Feb 13, 1976Feb 15, 1977Skil CorporationAttachment for a rotary-hammer tool
US4621870 *May 8, 1985Nov 11, 1986Santrade LimitedSupport for a cutting tool for cutting hard material
US4893875 *Dec 16, 1988Jan 16, 1990Caterpillar Inc.Ground engaging bit having a hardened tip
US4911504 *Jul 20, 1988Mar 27, 1990Kennametal Inc.Cutter bit and tip
US5494382 *Apr 19, 1994Feb 27, 1996Amic Industries LimitedDrill bit
US5685381 *Nov 1, 1995Nov 11, 1997Kennametal South Africa (Proprietary) LimitedDrill rod and drill bit with rocking connection
US6257673Oct 27, 1999Jul 10, 2001Ramco Construction Tools, Inc.Percussion tool for boom mounted hammers
US6938961 *Mar 21, 2003Sep 6, 2005Cutting Edge Technologies, LlcApparatus for breaking up solid objects
US8118371Jun 25, 2009Feb 21, 2012Schlumberger Technology CorporationResilient pick shank
US8201892Dec 10, 2007Jun 19, 2012Hall David RHolder assembly
US8215415 *Jul 8, 2002Jul 10, 2012Hawera Probst GmbhChisel
US8292372Dec 21, 2007Oct 23, 2012Hall David RRetention for holder shank
US8322796Apr 16, 2009Dec 4, 2012Schlumberger Technology CorporationSeal with contact element for pick shield
US8342611Dec 8, 2010Jan 1, 2013Schlumberger Technology CorporationSpring loaded pick
US8449040Oct 30, 2007May 28, 2013David R. HallShank for an attack tool
US8500210 *Jun 25, 2009Aug 6, 2013Schlumberger Technology CorporationResilient pick shank
US8678517 *Oct 20, 2010Mar 25, 2014Sandvik Intellectual Property AbReduced volume cutting tip and cutting bit incorporating same
US8701799Apr 29, 2009Apr 22, 2014Schlumberger Technology CorporationDrill bit cutter pocket restitution
US20040195008 *Mar 3, 2004Oct 7, 2004Broom Gilbert R.Method and apparatus for tapping a blast furnace
US20050098355 *Sep 8, 2004May 12, 2005Broom Gilbert R.Method and apparatus for boring through a solid material
US20120098326 *Apr 26, 2012Sandvik Intellectual Property AbReduced Volume Cutting Tip and Cutting Bit Incorporating Same
WO1990001105A1 *Jul 13, 1989Feb 8, 1990Kennametal IncCutter bit and tip
U.S. Classification299/113, 175/414, D15/139, 125/40
International ClassificationB25D17/02, B25D17/00
Cooperative ClassificationB25D17/02
European ClassificationB25D17/02