AU605842B2

AU605842B2 - Cutting tool

Info

Publication number: AU605842B2
Application number: AU13351/88A
Authority: AU
Inventors: Barend Johannes Liebenberg
Original assignee: Individual
Current assignee: Individual
Priority date: 1988-03-22
Filing date: 1988-03-22
Publication date: 1991-01-24
Anticipated expiration: 2008-03-22
Also published as: AU1335188A

Description

1.8 060Z99 ZL "'~111U zAxMAn sibdou w 1ii q Sopqo 1.25 1.6ml~ ZAXMAflIStdONW1)NFH0J9G1D9V 'Id 01 1.25 .4 16_ -m liiI m rn 1.2 I1.4 11 .6 -II jlirli~ i. 605842 S F Ref: 54204 FORM COMMONWEALTH OF AUSTRALIA PATENTS ACT 1952 COMPLETE SPECIFICATION

(ORIGINAL)

FOR OFFICE USE: Class Int Class Complete Specification Lodged: Accepted: Published: Priority: Related Art:

I'

s Name and Address of Applicant: AJdress for Service: Barend Johannes Liebenberg Roo1bekkie Street Presldentsdam, Springs Transvaal Province REPUBLIC OF SOUTH AFRICA Spruson Ferguson, Patent Attorneys Level 33 St Martins Tower, 31 Market Street Sydney, New South Wales, 2000, Australia Complete Specification for the invention entitled: Cutting Tool The following statement is a full description of this inventior, including the best m~thod of performing it known to me/us 5845/3 L 2 This invention relates to a coal pick. Coal picks require sharp or keen cutting edges to do their v,ork effectively. Hard cutting inserts have been used to provide long effective life of the cutting edges.

It is an object of this invention to provide for the easy and quick replacement of the cutting insert of a coal pick.

According to a first embodiment of the invention, there is disclosed herein a coal pick comprising: a) an insert holder having a shank part, a taper slot defined by a a pair of opposed, flat surfaces tapering down towards the bottom of the taper slot, and having a groove in one of the flat surfaces extending in a direction towards the bottom of the siot; and b) a cutting insert having a truncated, wedge-shaped body defined between opposed, flat surfaces tapering in a longitudinal direction of the So wedge-shaped body, a cutting edge at the thick end of the wedge-shaped J15 body, and a longitudinal ridge extending along one of the flat surfaces of the wedge-shaped body but stopping short of the cutting edge, the wedge-shaped body of the cutting insert being wedgable operatively in the taper slot of the insert holder with the longitudinal ride of the wedge-shaped body received by the groove of the insert holder, and the shank part of the insert holder being engageaule with a coal pick box.

In accordance with a second embodiment of the invention, there is disclosed herein a cutting insert for use in the coal pick of the first embodiment, the cutting insert comprising a truncated, wedge-shaped body defined between opposed, flat surfaces tapering in a longit,:dinal direction of the wedge-shaped body, a cutting edge at the thick end of the wedge-shaped body, and a longitudinal ridge extending along one of the flat surfaces of the wedge-shaped body but stopping short of the cutting edge, the wedge-shaped body being wedgeable in the taper slot of the insert holder.

In accordance with a third embodiment of the invention, there is disclosed herein an insert holder for use in the coal pick of the first embodiment, the insert holder comprising a shank part, a taper slot defined by a pair of opposed flat surfaces tapering down towards the bottom of the taper slot, and a groove in one of the flat surfaces extending in a direction towards the bottom of the slot, KLN/25651 1 o L -1

A

-3- The ridge may extend along the middle of one of the flat surfaces.

The degree of taper of the truncated wedge-shaped body may be slightly more than 60, say, 6 1/2° If desired, the degree of taper of the slot in the insert holder may be slightly smaller than the degree of taper of the trurnated wedge-shaped body of the cutting insert. The degree of taper of the slot may be and thus the difference between the tapers of the cutting insert body and the slot may be about 1/20. Such slight difference in taper ensures that the opposing taper faces of the taper slot of the insert holder are urged apart resiliently by the taper body of the insert when it seats snugly in the taper slot while in use.

The coal pick insert holder may have a shank shaped and dimensioned so that it may be held in a coal pick box.

The orientation of the taper slot relative to the coal pick shank may be such that the cutting edge of the cutting tool insert, while in use, has an angle of attack such that there is at least a component of force urging the insert into the slot.

There may be a clearance space between the bottom of the slot and the thin end of the body of the insert when the body is wedged in the slot for use.

The invention will now be described by way of example, with reference to the accompanying diagammatic drawings.

In the drawings, Fig. 1 shows a side elevation of a coal pick incorporating the 0 0 invention; Fig. 2 shows a front elevation at II-II in Fig. 1; Fig. 3 shows a plan corresponding to Fig. 1; Fig. 4 shows a detailed section side view at IV-IV in KLN/25651 i. i~ ;i t.

FIGURE 5 FIGURE 6 FIGURE 7 FIGURE 8 FIGURE 9 FIGURE 10 Figure 5 of a replaceable insert in a taper slot, to a larger scale than shown in Figure 1; shows a sectional view at V-V in figure 4; shows a side view of the cutting insert in accordance with anothtr aspect of the invention; shows a front view at VII-VII in Figure 6; shows a plan view corresponding to Figure 6; shows an end view at IX-IX in Figure 6; and shows a sectional end elevation at X-X in Figure 8.

000 0 oo a 0 0000 o so 00 00 000 0 Q Referring to the drawings, reference numeral refers generally to a coal pick which includes an insert holder 11 having a taper slot 12 defined by a pair of opposed flat surfaces 14 and 16 tapering down towards the bottom of the taper slot. The coal pick 10 also includes a cutting insert 18 in the form of a tooth having a cutting edge 18.1. The tooth 18 has a truncated wedge-shaped body defined between opposed flat surfaces 20.1 and 20.2 tapering in a longitudinal direction and seating snugly against the faces 14 and 16 of the taper slot 12. The tooth 18 has a longitudinal ridge 18.2 extending along the middle of the leading face 20.1 of the body 20, which fits snugly into a mating groove 16.1 provided in the flat surface 16 II~ i 000000 o 0o 0 000 0 00 00 0 o 0 0 0 0 0 0 0 0 0 0 0 0 0 0 oO f0 0 0 0 S0 0 0 00 0 0 0 0 00 0 0 00 0 0 4 0 4 defining the leading face of the taper slot 12, and extending in a direction towards the bottom of the slot. The ridge 18.2 prevents the tooth 18 from being laterally displaced out of the slot.

The length of the ridge 18.2 is matched to the depth of the mating groove 16.1 so that the inner end of the ridge 18.2 abuts against the bottom of the groove defined by a shoulder 16.11, so as to leave a clearance space 22 between the inner end of the body 20 and the bottom of the slot 12. Such a clearance space 22 permits the insertion of an extraction tool in the form of a flat-nosed lever whereby the tooth 18 may be levered out of the slot 1.2, when the tooth 18 needs to be replaced.

The slot 12 is orientated in such a way that the angle of attack of the tooth 18 will be such that the reactive force, while cutting, will be in the direction as indicated by arrow 24 and will have a component in the direction of arrow 24.1 which urges the tooth 18 into the slot 12.

The insert holder 11 further has a shank part 26 shaped and dimensioned so that it can be gripped by a coal pick box to permit cutting by the cutting edge 18.1 of the insert 18.

The degree of taper of the slot 12 in the insert holder 11 is slightly smaller than that of the body 20 of the tooth 18. The degree of taper of the body 20 is of the order of about 6 0, and the degree of taper of the slot 12 is about 60. Such a slight difference in the degree of S taper ensures that the opposing taper faces 14 and 16 of the slot 12 in the insert holder 11 are urged apart resiliently i by the taper body 20 of the insert 18 when the body 20 seats snugly in the taper slot 12 while working. The shank part 26 is held in the coal pick box (not shown) by means of one or more keys (not shown) engaging with the grooves 26.1 in the shank part 26.

It is an advantage of coal picks of this invention for the cutting of coal, that teeth 18 may be easily replaced when worn, by merely levering them out of the slots 12 of the coal picks 10 by means of simple hand tools. New teeth 18 may then easily be inserted by hand.

The teeth will then become firmly wedged into the slots 12 when the coal picks start working again.

In other words, worn teeth 18 may be replaced with little trouble, without the necessity of having the -7 coal picks 10 removed bodily from coal pick boxes.

The Applicants believe that such an arrangement will bring about a substantial saving in time in the replacement of worn teeth 18, over previous practice where it is necessary to remove the coal picks 10 bodily in order to replace the cutting edges.

Claims

1. A coal pick comprising: a) an insert holder having a shank part, a taper slot defined by a pair of opposed, flat surfaces tapering down towards the bottom of the taper slot, and having a groove in one of the flat surfaces extending in a direction towards the bottom of the slot; and b) a cutting insert having a truncated, wedge-shaped body defined between opposed, flat surfaces tapering in a longitudinal direction of the wedge- .shaped body, a cutting edge at the thick end of the wedge-shaped body, and a longitudinal ridge extending along one of the flat surfaces of the wedge-shaped body but stopping short of the cutting edge, the wedge-shaped body of the cutting insert being wedgable operatively in the taper slot of the insert holder with the longitudinal ridge of the wedge-shaped body S';received by the groove of the insert holder, and the shank part of the insert holder being engagable with a coal pick box.

A coal pick according to claim 1 wherein the angle of taper of the taper slot of the insert holder is less than that of the flat surfaces of the wedge-shaped body with the result that the flat surfaces of the insert holder are urged resiliently apart when the wedge-shaped body of the cutting insert is wedged into the taper slot,

3. A coal pick according to claim 2 wherein the angle of taper of the taper slot is 6" and that of the flat surfaces of the cutting insert is 61z, 9

4. A coal pick according to any one of the preceding claims wherein the orientation of the taper slot of the insert holder, relative to the shank part thereof, is such that the cutting edge of the cutting insert in use has an angle of attack such that there is at least a component of force urging the wedge-shaped body of the cutting insert into the taper slot.

A coal pick according to any one of the preceding claims wherein there is a clearance space in use between the bottom of the taper slot of the insert holder and the thin end of the wedge-shaped body of the cutting insert.

6. A cutting insert for use in a coal pick according to any one of the preceding claims, the cutting insert comprising a truncated, wedge-shaped body defined between opposed, flat surfaces tapering in a longitudinal direction of the wedge-shaped body, a cutting edge at the thick end of the wedge-shaped body, and a longitudinal ridge extending along one of the flat surfaces of the wedge-shaped body but stopping short of the cutting edge, the wedge-shaped body being wedgable in the taper slot of the insert holder.

7. A cutting insert according to claim 6 wherein the angle of taper of the flat surfaces of the wedge-shaped body is 61/2.

8. An insert holder for use in a coal pick according to any one of claims 1 to 5, the insert holder comprising a shank part, a taper slot defined by a pair of opposed, flat surfaces tapering down towards the bottom of the taper slot, and a groove in one of the flat surfaces extending in a direction towards the bottom of the slot. tr ("t 10

9. An insert holder according to claim 8 wherein the groove stops at a shoulder short of the bottom of the taper slot, the shoulder serving to limit wedging movement of the cutting Insert into the taper slot.

An insert holder according to claim 8 or claim 9 wherein the angle of taper of the flat surfaces of the insert holder is 6°.

11. A coal pick substantially as hereinbefore descrie'd with reference to the accompanying drawings.

12. A ,utting insert for use in the coal pick of claim 11, the cutting insert being substantially as hereinbefore described with reference to the accompanying drawings.

13. An insert holder for use in the coal pick of claim 11, the insert holder being substantially as hereinbefore described with reference to the accompanying drawings, DATED this SECOND day of OCTOBER 1990 Barend Johannes Liebenberg Patent Attorneys for the Applicant SPRUSON FERGUSON KLN/25651