WO1996008599A1

WO1996008599A1 - Improvements in mounting pick holders in cutter heads of mining machines

Info

Publication number: WO1996008599A1
Application number: PCT/AU1995/000518
Authority: WO
Inventors: Kieron Denz; Allan D. Clair
Original assignee: Cutincoal Pty. Limited
Priority date: 1994-09-15
Filing date: 1995-08-21
Publication date: 1996-03-21
Also published as: ZA957557B; AUPM815494A0

Abstract

The invention relates to mounting means for pick holders (8) in a cutter head (13) of a mining machine, said pick holder (8) comprising a head (9) with a shoulder (10) thereon and a cylindrical, cone shaped body (11) extending from the shoulder which terminates in a shank (12) whereby the pick holder (8) is secured in a corresponding bore in the cutter head (13), said mounting means comprising an elastomeric sleeve (19) positioned at least between the major mating surfaces of the pick holder (8) and the cutter head (13). The sleeve (19) can be initially moulded onto the surface of the cylindrical cone shaped body (11) and shoulder (10).

Description

IMPROVEMENTS IN MOUNTING PICK HOLDERS IN CUTTER HEADS OF MINING MACHINES

The present invention is concerned with pick holders of the type used for the purpose of mounting a pick on the rotary cutter head of a mining machine.

The mining machines with which such pick holders are used include a circular elongated cutter head having spiral rows of picks mounted thereon. The picks are housed in a holder secured on the head which is rotatably driven from an appropriate power source and the picks are brought into contact with a mining seam. As the cutter head is rotated the picks cut coal or other material from the seam. The number of picks and holders on a cutter head varies, a typical head would have from 100 to 300 picks mounted thereon. Mining machines of the aforesaid type are well known in the mining industry and are generally referred to as continuous or long wall miners. The holder comprises a head with a shoulder thereon and a cylindrical body extending therefrom which seats in a corresponding recess in the cutter head and which terminates in a shank whereby the holder is fixed to a cutter head.

The holder has a first axial bore therein so dimensioned so as to accommodate the shank of a pick which is retained in the holder by a securing clip on the pick which seats in an internal circumferential groove in the first axial bore.

A second smaller diameter axial bore extends from the bottom of the first axial bore through to the bottom of the pick holder thereby providing a seat for the pick shank. The second bore accommodates a knockout punch whereby the pick can be removed from the holder. Pick holders of the type described are well known in the mining industry. In the working environment of a mine it is difficult if not impossible to inspect and clean every bore on the cutter head. In consequence pick holders are often placed into dirty or worn bores. As the cutter head rotates each pick contacts the cutting seam and the shock loads transmitted through the pick and pick holder to the holder seat in the cutter head. Any slight movement between the pick holder and the seat causes wear between the mating surfaces. In consequence the pick holder works loose in its seat and as a result more rock and coal dust enters and is ground in the space between the mating surfaces which increases wear. Eventually the loose pick holder is noticed by the mine maintenance staff who will re-tighten the holding nut or replace the holder with a new one.

As wear between the mating surfaces increases the chances of properly mounting the holder on the head becomes less as time goes by and there comes a time when the only option is to replace the cutter head and fit it with new pick holders. This is a costly operation and there has been a need to provide means whereby the life period of a pick holder can be prolonged.

In the case of pick holders having a tapered body, a metal to metal taper lock fit between the pick holder and its mounting is not possible. This leads to point contact which increases wear and flogging of the receiving female taper and as the result of repeated flogging the mounting snaps off necessitating repair or a cutter head change.

The present invention provides a simple and relatively inexpensive method of overcoming the mentioned problems.

The invention comprises mounting means for mounting pick holders in a cutter head of a mining machine, said pick holder comprising a head with a shoulder thereon and a cylindrical body extending from the shoulder which terminates in a shank whereby the pick holder is secured in a corresponding bore in the cutter head, said mounting means comprising an elastomeric sleeve positioned at least between the major mating surfaces of the pick holder and the cutter head. Preferably the sleeve is made of polyurethane and preferably it is moulded to the surface of the head and body of the pick holder. It will be appreciated however that the sleeve can be manufactured separately and fitted to the pick holder.

A preferred embodiment of the invention will now be described with reference to the accompanying drawing in which the single figure is a sectional view of a pick, pick holder and relevant portion of a cutter head in accordance with the invention.

The pick designated generally by the reference 1 comprises a cone shaped head 2 having a pick point 3 and a shank 4 extending therefrom. The head is provided with a circumferential extraction groove 5 and a securing clip 6 accommodated in a circumferential groove 7. The pick holder designated generally by the reference 8 comprises an enlarged head 9 provided with a shoulder 10. A tapered cone shaped body 11 extends from the head and terminates in a threaded shank 12 whereby the holder is fixed to a mounting 13 on the cutter head with the aid of a nut 14 and washer 14a.

The holder has a first axial bore 15 so dimensioned to accommodate the shank 4 of a pick 1 therein. The bore is provided with a circular groove 16 which accommodates the securing clip 6 mounted on the shank 4 of the pick 1.

A second smaller diameter axial bore 17 extends from the bottom of the axial bore 15 through to the back of the pick holder. Preferably the bore 17 is tapered as shown. The second bore accommodates a knockout punch (not shown) whereby the pick can be removed from its holder.

A cone shaped bore 18 complementary to the body 11 is formed in the mounting 13.

An elastomeric sleeve 19 is positioned on the body 11 and in use the sleeve 19 is sandwiched between the mating surfaces of the body 11 and the bore 18 in the mounting 13. Preferably the sleeve 19 is moulded on the surface of the body 11 and shoulder 10.

In relation to new pick holders the shoulder 10 and body 11 are machined about

4 mm under size and polyurethane about 4 mm thick is moulded to the mating faces. This allows the holder to be pulled back tightly to the mounting bore 18. The polyurethane accommodates any imperfections between the mating surfaces and leads to a better and long lasting interfit of the mating parts.

In relation to worn mounting bores 18 a range of oversize pick holders can be manufactured with the polyurethane sleeve cast in different colours to identify a selected range of sizes. In this way existing pick holders can be converted or reconditioned by remachining the taper and shoulder and then coated with polyurethane as described herein.

The use of the elastomeric sleeve provides a high resistance to wear and impact loads so that the working life of the pick holder, mounting and the cutter head is greatly prolonged with a consequence of considerable savings for the mine operator.

Claims

CLAIMS:

1. Mounting means for mounting pick holders in a cutter head of a mining machine, said pick holder comprising a head with a shoulder thereon and a cylindrical body extending from the shoulder which terminates in a shank whereby the pick holder is secured in a corresponding bore in the cutter head, said mounting means comprising an elastomeric sleeve positioned at least between the major mating surfaces of the pick holder and the cutter head.

2. Mounting means as claimed in claim 1 wherein said sleeve is formed of polyurethane

3. Mounting means substantially as hereinbefore described with reference to the accompanying drawings.