GB2178782A

GB2178782A - Improvements in cutter-bit assemblies

Info

Publication number: GB2178782A
Application number: GB08618685A
Authority: GB
Inventors: Norbert Hesse; Oswald Breuer
Original assignee: Gewerkschaft Eisenhutte Westfalia GmbH
Current assignee: Gewerkschaft Eisenhutte Westfalia GmbH
Priority date: 1985-08-06
Filing date: 1986-07-31
Publication date: 1987-02-18
Also published as: FR2586060B1; DD247484A5; FR2586060A1; DE3528176A1; GB2178782B; GB8618685D0

Abstract

A cutter-bit assembly is composed of a cutter-bit 2 with a shank 9 fitting into a pocket 3 of a holder 1.The shank 9 has a recess 10 at the rear which engages on a curved inner face 11 in the pocket 3 and a depending claw 14 which locks beneath a projection 23 at the base of the 24 pocket 3. A curved front face 13 of the shank 9 forms an arcuate gap 24 with a rear inner face of a front wall of the pocket. A wedge element 16 locates in the gap 24 to engage on the inner face of the front wall and fits around the front wall. A pressure piece 21 locates in the gap 24 to engage between the element 16 and the front face 13 of the shank 9. Clamping sleeves 20, 22 additionally secure the element 16 and the pressure piece 21. <IMAGE>

Description

SPECIFICATION Improvements in cutter-bit assemblies The present invention relates to cutter-bit assemblies for use in mining ortunnelling.

Cutter-bitassembliesofvariousdesignsarewidely used in mining and tunnelling operations. Normally, such assemblies are composed of a holder secured to a cutting appliance or machine, such as a coal plough, and a separate cutter-bit which is inserted into a pocket in the holder. To secure the cutter-bitwithin the holder it is known to employ a wedging element which jams a shank of the cutter-bit in the pocket. To secure the element in position a deformable lug ortab can be bent around a front wall ofthe pocket. During use of the assembly, however, especially when the assembly is subject to impact stress, deformation and wear can cause the loosening ofthewedge and the cutter-bit and chattering and damage can then occur.

The service life ofthe cutter-bits can be improved significantly ifthe means used to securethe cutterbits in the holders is made more reliable. With this in mind, the present invention seeks to provide improved cutter-bit assemblies.

According to the invention, a cutter-bit assembly comprises a holder defining a pocket, a cutter-bit having a shank mounted in the pocket, an arcuate tapered gap between the shank and an inner face of the pocket, part-resilient locking means fitted in the gap to return the shank in the pocket and a depending claw on the shank which locates beneath a projection in the pocket of the holder.

In a preferred construction, the invention provides a cutter-bit assembly comprising a holder defining an open pocket, a cutter-bit having a shank mounted in the pocket and a blade with a cutting edge disposed outside the pocket, an arcuate tapered gap between the shank and an innerface ofthe pocket and nearest the cutting edge, a removable element located in the gap to engage on the inner face ofthe pocket and a removable pressure piece located in the gap to engage on the element and on a face ofthe shank and a depending portion on the shank which engages in hook-like fashion beneath a projection in the pocket.

In a manner generally known persethe element and pressure piece can both be arcuate and the major end region ofthe element can be turned-over as a lip orflange orotherwise pre-shapedto engageovera frontwall ofthe pocket, which has the curved inner face defining the arcuate gap, and can lie in a shallow recess. This forms a reliable stop and preferably additional retention means is provided in the form of a clamping sleeve which engages in bores in the front wall and in another region, conveniently the minor end region, ofthe element.A lateral clamping sleeve can also be provided forthe pressure piece which is preferably a tough elastic component urging the claw tightly underthe associated projection in the pocket.

At the rear ofthe shankthere is preferably some form of shaped abutment with a rear wall ofthe pocketto provide additional support. For example, a curved recess in the shank can engage on a curved surface of a pin ora rearwall.

During use of an assembly constructed in accordance with the invention the cutting forces are transferred directly to the holder by virtue ofthe pressure piece and the wedge element is only subjected to moderate force. The means which locksthe shank in the pocket also ensures that the cutter-bit is reliably held in position even when subjected to high forces particularly impacts. The cutter-bit can be removed for replacement or re-sharpening by releasing the pressure piece and wedge eiement.

The invention may be understood more readily and various other aspects and features of the invention maybecomeapparentfrom consideration ofthefol- lowing description.

An embodiment ofthe invention will now be described, by way of example only, with reference to the accompanying drawing, which is a part-sectional side view of a cutter-bit assembly constructed in accordance with the invention.

As shown in the drawing, a cutter-bit assembly is composed of a holder 1 and a cutter-bit 2 retained in the holder 1 with means described hereinafter. The holder 1 is fixed or detachably mounted to some appliance, e.g. a mineral winning machine such as a plough orto a tunnel driving machine orthecutting means thereof. The cutter-bit 2 is a shaped metal plate with a shank portion 9 received in the holder 1 and a blade portion 8 outside the holder 1 which has a hard-metal insert(notshown) atitsfrontend (atthe left-hand side ofthe drawing) which forms a cutting edge. The holder 1 is of generally rectangularcon figuration with a pocket 3 open from the top to receive the shank 9 of the cutter-bit 2. The pocket 3 is defined by parallel side walls and is partially open to thefront, rear and the bottom.More particularly, the holder 1 has an apertured rear wall 4 an apertu red front wall 5 and an apertured basewall 6. The inner faces of the front and rearwalls 5,4 are curvilinear i.e. convex. A hook-like projection 23 extends into the pocket 3 from the base. The shank 9 ofthe cutter-bit 2 is provided with a semi-circular recess 10 at its rearwhich engages on the curved inner face 11 ofthe rearwall 4.

The lower rear region of the shank 9 beneath the recess 10 forms a projection or nose 12 which engages in hook-like manner beneath the rear wall 4.

When the shank 9 is inserted into the pocket 3the recess 10 can be engaged on the face 11 and the cutter-bit2 can be swivelled into the pocket3 about the face 1 1.The shank 9 has a depending claw 14, which also engages beneath the projection 23 in hook-like mannerwhen the cutter-bit2is located in the pocket 3.

Thefrontface 13 oftheshank9 is concave and an arcuatewedge shaped gap 24 Is defineu by the inner face of the front wall 5 of the holder 1 andthefront face 13 of the shank 9. This gap 24 receives wedging means which serves to secure the cutter-bit shank 9 in the pocket 3. The wedging means includes an arcuate-shaped element 16 and a pressure piece 21 which collectivelyfittightl / n t.-e gp 24to -thesP k9 in the pocket 3. The element 16 engages around the innerface ofthe wall 5. The major region orthickest end region ofthe element 16 has a lip 17 orthe like which engages in a recess in the front of the wall 5 thereby to form a stop. A bore 18 extends through the minor or narrowest end region of the element 16 and aligns with a bore 20 in the wall 5. A clamping sleeve 19 is engaged through the bores 18, 20 to lockthe element 16 in place.

The lateral dimension of the gap 24 is such thatthe curved front face 13 ofthe shank9 is offset from the element 1 6which embracesthewall S. This creates a further arcuate space 15 between the element 16 and the face 13 which is fitted with the pressure piece 21.

This component 21 is preferably made from atough, durable, elastic or resilient plastics material such as 'Vulkollan'which itself is secured buy a lateral clamping sleeve 22. When fitted as shown the pressure piece 21 ofthe wedging means 16, 21 urges the shank 9 rearwardlyto lock the claw 14againstthe projection 23 and the recess lOon the face 11. The rearwardlydirected cutting forces acting on the blade 8 arethen transmitted to the holder via the projection 23 andthe rearwall 4withoutsubjectingthe element 16to any stress orstrain.

Claims

1. Acutter-bitassemblycomprising a holderde- fining an open pocket, a cutter-bit having a shank mounted in the pocket and a blade with a cutting edge disposed outside the pocket, an arcuatetapered gap between the shank and an innerface of the pocket and nea rest the cutting edge, a removable element located in the gap to engage on the innerface ofthe pocket and a removable pressure piece located in the gap to engage on the element and on a face ofthe shank and a depending portionontheshankwhich engages in hook-like fashion beneath a projection in the pocket.

2. An assembly according to claim 1, wherein the pressure piece is resilient.

3. An assembly according to claim 1 or2, wherein the pressure piece is secured with a lateral clamping sleeve.

4. An assembly according to claim 1,2 or3, wherein the element has a majorfront region which engages in the recess in a front wall ofthe pocket adjacent the cutting edge to form a stop.

5. An assembly according to any one of claims 1 to 4, wherein borings provided in the element and the wall ofthe pocket receive a clamping sleeve.

6. An assembly according to claim 4wherein the element has a minor inner region which has a through bore which aligns with a bore in thefrontwall ofthe pocket beneath the recess and a clamping sleeve is fitted into the bores.

7. An assembly according to any one of claims 1 to 6, wherein the pressure piece is made from a dur- able resilient material.

8. Acutter-bitassemblycomprising a holderdefining a pocket, a cutter-bit having a shank mounted in the pocket, an arcuate tapered gap between the shank and an innerface of the pocket, part-resilient locking means fitted in the gap to retain the shank in the pocket and a depending clawontheshankwhich locates beneath a projection in the pocket of the holder.

9. An assembly according to any one of claims 1 to 8, wherein the shank has a curved recess opposite the gap which engages on a further curved innerface in the pocket.

10. An assembly according to any one of claims 1 to 8, wherein the shank and the pocket have rear abutment means opposite the gap.

11. A cutter-bit assembly substantially as described with reference to, and as illustrated in,the accompanying drawing.