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United States Patent 3,807,804
Kniff April 30, 1974

IMPACTING TOOL WITH TUNGSTEN CARBIDE INSERT TIP

Abstract

An impacting tool in which a massive hard carbide element is fitted to a steel holder which is reciprocated to drive the element against a formation to be broken. The massive carbide element can be press fitted in the steel holder or shrink fitted therein or brazed thereto and, furthermore, the carbide element can be fitted to a steel sleeve adapted for being secured to a steel holder as by threading or brazing.


Inventors: Kniff; Thomas J. (Bedford, PA)
Assignee: Kennametal Inc. (Latrobe, PA)
Appl. No.: 05/288,292
Filed: September 12, 1972


Current U.S. Class: 299/113
Current International Class: B25D 17/00 (20060101); B25D 17/02 (20060101); E21c 013/01 ()
Field of Search: 299/91,94 175/410,413 279/96,103 29/525

References Cited

U.S. Patent Documents
3268260 August 1966 Snipe
3356418 December 1967 Healey et al.
2161062 June 1939 Killgore
Primary Examiner: Purser; Ernest R.
Attorney, Agent or Firm: Crosby; Melvin A.

Claims



What is claimed is:

1. In an impacting tool; steel holder means, a blind cylindrical bore extending into said holder means from the working end thereof, and an impact member in the form of a single cylindrical piece of cemented hard metal carbide material fixed in said bore and having a pointed end protruding from the working end of said holder means, the axially inner end of said impact member bearing directly on the bottom of said bore in load transmitting relation thereto.

2. An impacting tool according to claim 1 in which said material comprises cemented tungsten carbide.

3. An impacting tool according to claim 1 in which said impact member is brazed in said bore.

4. An impacting tool according to claim 1 in which said impact member is cemented in said bore.

5. An impacting tool according to claim 1 in which the pointed outer end of said member comprises a first portion at the point having a wide angle and a second portion adjacent thereto having a narrow angle.

6. An impacting tool according to claim 1 in which said impact member is press fitted into said bore.

7. An impacting tool according to claim 6 in which said bore has an undercut at the bottom to receive any shavings taken by said impact member when it is pressed into said bore.

8. An impacting tool according to claim 6 in which said impact member has a tenon formed on the end in said bore to provide a space to receive any shavings taken by said member when it is pressed into said bore.

9. An impacting tool according to claim 1 in which said holder means comprises a first axial portion at the working end through which said bore extends, and a second axial portion connected to said first portion and having a region forming the bottom of said bore.

10. An impacting tool according to claim 9 in which said portions are connected by welding.

11. An impacting tool according to claim 9 in which said portions are threaded together.
Description



The present invention relates to an impact tool, especially to a heavy duty impact tool adapted for being driven by a motor against a formation or rock to be broken.

Impacting tools are known in which an arrangement is provided for driving an impact tool against a rock or formation to be broken or reduced. Reciprocating motors can be employed for reciprocating the impact tool and the motor can either be fluid operated or pneumatically operated. Such impact tools are also adapted for being dropped under the influence of a weight against a region to be impacted thereby.

In the past, hard steel has been employed as the impact tool, or at least the working end of the impact tool, has been formed of hard steel or has been hard faced.

While hard steel and hard facing produces a more wear resistant working end on the impact tool, such treatment of steel leaves a great deal to be desired in the way of wear resistance and hardness.

Such impact tools have been provided with small inserts of hard cemented metal carbide material and this greatly improves the wear resistance of the working end of the tool but, nevertheless, the steel in which the carbide elements are mounted tends to wear away leaving the elements exposed and will sometimes mushroom and create difficulties.

With the foregoing in mind, the present invention proposes the provision of an impact tool of the nature referred to which avoids the drawbacks referred to above in connection with prior art impact tools.

A particular object of the present invention is the provision of an impact tool in which only a single massive wear resistant element is provided as opposed to the provision of multiple wear resistant elements.

Still another object is the provision of an impact point arrangement for an impact tool which can be fitted to a worn impact tool, or detachably mounted on an impact tool formed in such a manner as to receive the point.

The foregoing objects as well as still other objects and advantages of the present invention will become more apparent upon reference to the following detailed specification taken in connection with the accompanying drawings in which:

FIG. 1 is a fragmentary view partly in section showing the working end of an impact tool according to the present invention.

FIG. 2 is a view like FIG. 1 but shows a modification.

FIG. 3 is a view like FIG. 1 but shows still another modification.

FIG. 4 is a fragmentary sectional view showing how a pocket could be formed in the steel holder of the tool for receiving shavings when the hard wear resistant tip is pressed into the holder.

FIG. 5 is a view similar to FIG. 4 but shows another manner of forming the pocket for receiving shavings.

BRIEF SUMMARY OF THE INVENTION

According to the present invention, a steel member of substantial size is provided which is adapted for being impelled forcibly in the axial direction against a formation or a rock which is to be reduced or broken up. According to the present invention, a massive piece of hard cemented metal carbide, such as cemented tungsten carbide, is mounted in the working end of the steel member and provides a hard wear resistant tip by means of which the tool impacts on the formation or rock. The steel member thus forms a holder and is referred to herein in this manner.

The carbide can be pressed into the steel holder or shrink fitted therein or brazed in position or otherwise secured to the steel holder so as to be fixed thereto. The end of the piece of carbide disposed in the steel holder takes a bearing directly on the holder and is, thus, efficient for transferring the energy from the holder into the work engaged by the outer end of the carbide piece.

The carbide piece can be mounted directly in the holder, or it can be mounted in steel retaining ring which is welded to the end of a steel holder or threadedly engaged therewith.

DETAILED DESCRIPTION OF THE INVENTION

Referring to the drawings somewhat more in detail, in FIG. 1, 10 indicates a steel body adapted to reciprocate in the direction of arrow 12 so as to drive the working end thereof against a formation or rock. The body 10 forms a holder for a hard wear resistant tip and the lower end of the holder is formed with an axial bore 14 and mounted therein is a massive tip element 16 formed of hard wear resistant material, in particular, cemented metal carbide, especially cemented tungsten carbide.

The tip element 16 has a cylindrical portion closely fitting in bore 14 and outwardly beyond the lower end of holder 10 tapers inwardly along a first region 18 at one angle and then tapers inwardly more sharply along a second region 20 to a point.

The holder 10 commencing at about the lower end of the cylindrical region of tip element 16 tapers outwardly at a first angle along a region 22 and then outwardly at a lesser angle along a region 24 to the outer periphery of the holder.

The carbide tip element 16 can be press fitted into bore 14, or holder 10 can be heated for receiving tip element 16 thereby providing for a shrink fit of the tip element in the holder or the tip element can be brazed into the holder by placing it in bore 14 with braze material in surrounding relation thereto and heating the holder and tip element to brazing temperature.

It will be appreciated that the upper end of tip element 16 at 26 takes a firm solid bearing on the surface at the bottom of bore 14 for an efficient transfer of energy from holder 10 into tip element 16.

As will be seen in FIG. 2, a tip element 16 can be fixed in a steel support ring 28 and the steel support ring 28 welded, as by welding 30 to the lower end of a steel holder 32 which has been cut off to receive the ring 28. Preferably, both ring 28 and holder 32 are cut off to provide an annular V-shaped recess in which the welding material 30 is received.

Tip element 16 in FIG. 2 extends completely through ring 28 and it will be noted that the upper end 26 thereof takes a full and solid bearing on the lower end of holder 32.

In FIG. 3, tip element 16 is fitted in a steel ring 34 which is provided with threads 36 at the upper end adapted threadedly to engage threads 38 formed on holder 40. When ring 34 is torqued up tight on holder 40, the upper end 26 of tip element 16 will take a firm bearing on the downwardly facing lower end of holder 40.

It has been mentioned that tip element 16 can be press fitted into the holder and FIG. 4 shows how a holder 42 could be provided with a pocket 44 adjacent the bottom of the bore in which tip element 16 is pressed so that any shavings taken from the holder by the tip element during the pressing of the tip element into the bore in the holder will be received in the pocket 44 and will not be disposed between the inner end 26 of tip element 16 and the bottom wall of the bore in the holder.

FIG. 5 shows a manner in which a tip element 16a could be provided with a region thereof at the inner end at 46 somewhat reduced in diameter thereby to provide a pocket 48 for receiving any shavings taken by the tip element as it is pressed into the holder. Both of FIGS. 4 and 5 show arrangements wherein the inner end of the tip element takes a full solid bearing on the bottom of the bore in the holder when the tip element is pressed into the holder. The pockets of FIGS. 4 and 5 are not required for the FIGS. 2 and 3 modifications because the rings shown therein in which the tip elements are mounted can be freed of shavings before assembly with the holder.

All of the modifications illustrated and described are characterized in the use of a single massive piece of cemented carbide, preferably tungsten carbide, to form the working end of the impact tool.

By way of example, such a carbide tip element might be 13/4 inches in diameter by about 5 inches long and could weigh as much as about 6 pounds.

Greatly increased utility of the impact tool results from the use of the hard metal carbide insert element according to the present invention with the tool having greater penetrating power and substantially longer life.

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