CA1170284A

CA1170284A - Cutter bit assembly

Info

Publication number: CA1170284A
Application number: CA000404554A
Authority: CA
Inventors: Gerhard Merten; Oswald Breuer; Norbert Hesse; Bernd Steinkuhl
Original assignee: Gewerkschaft Eisenhutte Westfalia GmbH
Current assignee: Gewerkschaft Eisenhutte Westfalia GmbH
Priority date: 1981-06-06
Filing date: 1982-06-04
Publication date: 1984-07-03
Also published as: AU545638B2; GB2100774B; PL236783A1; FR2507244B1; DE3209410A1; PL136339B1; GB2100774A; ES273600Y; DE3209410C2; FR2507244A1; SU1309916A3; AU8436682A; CS236479B2; ES273600U

Abstract

ABSTRACT OF THE DISCLOSURE
A cutter bit assembly comprises a holder and a cutter bit. The holder is formed with a pocket into which the cutter bit can be inserted. The cutter bit is retained within the pocket by means of an arcuate wedge inserted into a tapered gap formed between respective curved support faces formed on the cutter bit and the holder.

Description

i 1 70284 BACKGROUND TO THE INVENTION
. _ _ . . , This invention relates to a cutter bit assernbly, and in particular to a cutter bit assembly for a mineral winning machine such as a coal plough.
A known coal plough cutter bit assembly has a holder defining a poclcet in which a body portion of a cutter bit is received. ~he cutter bit may have a pro~ection which hooks into a recess in an end wall of the holder, while the other end of the cutter bit body is held in place by a detachable securing device. The detachable securing device may be a liner which is inserted into a gap between opposed surfaces of ~he cutter bi~ body and the holder. A known ~ype of liner is constituted by a thln metal plate which is loosely inserted i.nto this gap.
The plate~(liner) is held in place by, for example, a dowel sleeve whlch is driven through aligned bores in the liner and the cutter bit body.~ ~In order to release the cutter bit from the holder, l~ ls~first nécessary to release the dowel;sleeve and to remove the liner.~ The cutter bit can then be moved forward in the pocket a~sufficlent distance 0 to unhook the~projection of the cutter bit~body from the recess in the end wali of the hoider.~ The~reafter, the cutter bit can be sw~mg laterally out of the pocket o~

, "~ .

~ 1 70~8~
",.~.

the holder, the open end of which pocket is di~ected towards the face belng won. An assembly of this type is described in DE-PS 1291708.

In another kno~n cutter bit assembly of this type, the dowel sleeve is replaced by a locking plate. The locking plate is bent over towards the outer face of the holder (or the cutter bit body) to hold the liner in place.
(See DE-OS 2 355 554).
In the known types of cutter bit assembly, the parts of the holder which support the cutter bit body~
undergo deformatioD and wear durlng use. This is because o~ the jolting of ~he cutter bit body against the support faces of the holder. The wear of the support surfaces of the holder (and the wear of the associated parts of the cutter bit body) is unclesirable, as it resu].ts in a loose ~; :
fit of the cutter bit within the holder~.
The aim of the invention is to provide a cutter b~it assembly whose cuttor bLt~ce ~be:~flnnly~and~eliab~ly~
secured in its~ holder; and~which~can,~ when~necessary, be 20 ~ ~uickly~and easily ret~ightened.
SUMMARY OF;THE I-NVENTION
The present inventlon~provides a cutter~bit assembly cornprlsing~a~holder and a~cutter bi~, the holder being~formed wi~L~h a~pocket into- which ~the cutter :

'. ., ~ . .

.
.

1 3 7028~

bit is insertable, wherein the cutter bit is, in use, retained witllin the poc~et by means of an arcuate wedge inserted into a gap formed between respective curved support faces formed on the cutter bit and the holder.
Advantageously, the curved support faces are formed at respective first ends of the cutter bit and the holder. Preferably, the cutter bit is formed with a projection~which is engageable with a complementarily~
shaped portion of the holder to help retain the cutter bit within the pocket, the projection and the comple-mentarily-shaped porti.on being formed on respective end portions of the cutter bit and the holder remote from said first ends.
In a preferred embodiment the cutter bi.t support lS face~is conc ve and the holdel support face is convex.
Convenlently, the centres~ of curva~ture~of the~two support faces are offset from one another~t~s~o that,~when the cutter bit~ls~ fulIy inserted~into~the pocket, the support faces deflne~a tapered~gap lnto~whlch~the arcuate wedge is insertable. Advantageously,~ the holder support face is~formed on a web posi~tioned at~said first end of the holder, and~the holder lS formed wlth~an aperture, the aperture belng~posltloned ad~acent to~the web ln such a ~anner that, when the cutter ~it is fully inserted Into , ' ;
::

, , :

, ' , ~; ::

1 ~ 7~2~1 the pocket, the arcuate wedge can be inserted through said aperture and into the gap between the curved support faces.
With the aid of the arcuate wedge, the cutter bit S can be firmly clamped within the pocket of the holder.
Moreover, if necessary, it can be retightened during use, this being accomplished by, for example, hc~mmer blows applied to the readily accessible thick er-d of the wedge.
The use of the arcuate wedge results in relatively large wedge support faces, so that excessively high specific sur~ace pressures on the wedge and its support faces are avoided.
Advantageously, the cl1rved support face of the holder extends over an arc of at least 130, and lS preferably be~tween 150 and 170. The arcuate wedge can be designed to be self-locking, so that a~y movement of the wedge out of~the tapered gap cannot occur during use. Moreover, the arrangement may be such that the ~

:
clamping force of the wedge is actually increased by the operational Eorces~ whic~ tend to force the cutter bit furthér into the pocket.
In a preferred embodiment, the thin end portion of the arcuate~wedge is of reduced cross-section, said reduced cross-section end portion having a thîckness .
., ~
, .
~ .

~ 7 ~ 7(~2~
, , which is s~aller than the width of the gap formed between the adjacent portions of the support faces when the cutter bit is fully inserted into the pocket. Advantageously, said red~tced cross-section end porti.on o~ the arcuate wedge is formed with at least one slot terminating at, and extending substantially at right-angles to, the free end of said portion. This slotted end portion defines --thin tongues which can be bent over against the adjacent web of the holder~to secure the wedge to the holder.
Consequently, a separate locking member (such as a dowel sleeve or a locking plate) is not required. The reduced cross-section of this cnd ~ortion ~acilit~tes the bending over of the tongues.
Preferably, the arcuate wedge extends over an arc which is at least~10 larger than the arc of the curved~support face~of the holder.
Advantageously, the end portlans o~the~cutter bit and the holder~retnote from said first ends arè
fo~ned;~wlth~respective~ complementarlly curved`support surfaces, sald support~sur~aces be~ng engagea~ble when the cutter blt is~fully inserted lnto the~pocket.
Preferably, the~cutter blt lS provlded with a concave support~surf~ace and~the holde~r~ls provided wlth a convex support surface.~ With this arrangement, large , .~ ,, .
.
~ . .

7~2 8 .
support surfaces can be provided on the cutter bit and the holder, so that e~cessively high specific surface pressures can be avoided at this end of the assembly.
Conveniently, the cutter bit has a cutter bit body and at least one cutting edge, the cutter bit body being insertable into the pocket in the holder, and the or each cutting edge being positioned outwardly of the pocket when the cutter bit body is fully inserted into the pocket. In a preferred embodiment, the cutter bit :
has two cutting edges, the cutter bit being of ; symmetrical construction having its two cutter edges syn~letrically di.sposed with respect to a median plane of the cutter body, and wi.th its concave support Lace and its concave support surface symmetrically~disposed :: :
with respect to said.median~plane. In ~this case, the cutter blt is~reversible ln~the~ h~o~lder.~
In ano~ther pre~erred~embodlment,~a~cylindrlcal rod associated~with~said end~portlon~of~the~holder constitutes the support surface o~f the~ho~lder~
Advantageously, the~ two ends of the~cyllndrlcal rod are held within complementarily-shaped;apertures formed in ~: ;
the holder. ~Prèferably~, the~two ends o~f the cylindrical rod are press-fitted into ~heir apertures, and the cyl mdrical r~od is supported by~a cylindrical support .~,, ~ : :

. . ... , . ~,.. ,, . i , ~ .

~ ~ 7~28~
, g surface forrned in said end portion of the holder.
Conveniently, the holder is made by casting, and the cylindrical rod is made of stainless steel.
BRIEF DESCRIPTION OF THE DRAWINGS
_ _ ......... ..... ..... _ ~
Three forms of cutter bit assembly, each of which is constructed in accordance with the invention, will now be described, by way of exarnple, with reference to the accompanying clrawings, in which:-FIG. 1 is a part-sectional side elevation of the first form of cutter bit assembly, and shows the cutter bit separated from its holder;
FIG. 2 is a perspective view of a wedge which forms part of the assembly of Fig. l;
FIG. 3 is a cross-section taken on the line :
III-III of Fig. l:
.:
FIG. 4 lS a transverse~ross~-section~of the~

assembly of ~igs. l to 3;

FIG. 5 is a view looking in the direction of the arrow V s~hown in Fig. 4;

FIG. 6 lS a part-sectional slde elevat~on of the ; ~ secood forrn of cutter blt assembly;

FIG. 7 ls~a part-sectional side ~elevatlon of the s~ third for~n of cutter bit assembly; ~and : ~

...
,~

,~ - 10 -FIG. 8 is a plan view of the holder of the assembly of Fig. 7.
DESCRIPTION OF PREFERRED EMB0D:tMENTS
Referring to the drawings, Figs. 1 to 5 show a cutter bit assembly cornprising a holder 10 and a cutter bit 11. The cutter bit 11 has a cutting edge 12 which is constltuted by a hard-metal insert. In a known manner, the holder 10 can be fitted, either permanently or in a detachable manner, to a coal plough or other winning machine.
The holder 10 is provlded with a pocket 13 which accommodates the cutter bit 11, the pocket being open at ~ the side (that is to say towards the ~ace to be~won).
; One end wall 14 of the pocket 13 is formed wlth a recess 15,~ the recess being positioned ad~acent to the-base 18 of the~holder l0 (that lS to say~remote from the open side of the~pocket). The other end;~of the pocket`~13 is provlded~wl~th a web 17,~ the web and the~base~ 18~definlng an end aperture~16. ~
The~cutter bit ll is of p]ate~ ke const~ruction, :: `
and is formed with~a projection l9 at the rear~end~(that is to say the end theréof~remote~ from the cutting edgè
12). When the cutter bit~ll;is~inaerted lnto the pocket 3, the projectlon l9 hooks round the`end wall 14 and :

~ ~ 7~28~
-into the recess 15 (see Fig. 4), thereby preventing the cutter bit from falling out of the pocket. The cutter bit 11 is formed with a convex end face 20 which, when the cutter bit is inserted fully into the pocket 13, is supported against a cornplementary concave face 21 formed on the end wall 14.
The front end (that is to say the ~nd adjacent to the cuttin~ edge 12) of the cutter bit 11 is formed with a concave recess 72. The recess 22 de~ines a support face for an~ar~uate weclg~ 23. Tlle re~ar face 24 of the web 17 defines a concave support face for the wedge 23. As shot~n in Fig. 4, the centre point 25 of the face 24~ is off-set slightly outwardly with respect .:
to the centre point~26 of the;face 22, so that the two faces 22 and 24 deilne a gap whlch tapers;from the end communicating with the~end~aperture 16. The~ace 24 of the web 17 extends over~an~arc of approxlmately~150 to 170.
As sho~n best in Flgs.~2: and 4,~the~wedge 23 extends over an arc~whlch lq approxlmately 10~to 40 greater than the arc~o~ the~ace 24. Lhe; end zone~27 , : ;
of the wedge 23 is~o~ reduced thickness~ as compared with the rest o the wedge. The;~e~nd zone 2~7 is~ also provided~
with an arcuate slot 28, this~ slot dividing the end zone ::
.
. . ..... ~ .~

:

11 ~ 7~8~

to form two thin tongues 29.
In order to position the cutter bit 11 within the holder 10, the cutter bit is introduced, with a rotary movement, into the pocket 13 from the open side.
~len the projection 19 hooks round the end wall 14 and into the recess 15, and the concave end face 20 of the cutter bit 11 is supported by the face 21 of the holder end wall 14 ~ the wedge 23 is driven into position through the end apertnre 16 and into the tapered gap between the faces 22 and 24. This can be done by hammer blows applied to the thick end 30 of the wedge 23. In thls way, the cutter hLt 11 is firmly fixed within the pocket 13 of the hoIder 10. In order to reta m the wedge 23 ln thls position, one of the tongues 29 is bent back over the web 17 (see Flgs. 4 and'~5). If:the cutter ; blt ll becomes loosened during use, lt can be re~-fixed within the pocket 1~3 by drlvlng the;wedge 23~f~urther into the tapered gap defined by he~faces~22 and~24.
The other tongue 29~can then be bent back over the web 17 to retain the wedge 2~3 in;~thls new;posl~ion.~ ~
In order to release tile cutter bit ll, it is necessary only to drive the wedge 23 out of the tapered gap in the opposite direc~tion to which it was driYen in.
~rior to driving ou~t~the wedge 23, the tongue (or ~ : ' :
: ~ : , ;
, .. ,,, . .. ~, .. . .

2 ~ 4 tongues) 29 must be lifted O~lt of the bent-back position. The wedge 23 can be driven out of the tapered gap by hammer blows applied to the tongues 29, or by means of a special tool (not sho~n) introduced into the reduced end portion of the tapered gap.
Alternatively~ the end 30 of the wedge 23 may be gripped by a tool, and the wedge pulled out at the end aperture 16.
Fig. 6 shows a modified forrn of cutter bit assembly having a holder 10' and a cutter bit 11'. This assen~bIy is similar to that of Flgs. 1 to 5, so like ~ .
reference numerals have been used for like parts, and .
~ only the modified parts wi].l be described in detail.
:
Thus, the end wail of the holder~lO' of the Flg. 6 embodiment defines a convex support~face~21', which extends substantially the entire depth oL the holder,~
The c~ontours of~the~face 21' correspond~substantlally with ~those~of~arcuatc face of~he~wedg-~2~3 that~ es~
agalnst the~ concave recess~22 forme~d~at~the~other~end 20 : ~o the holder;10'.~The cutter blt~ s ~forrned~with ` a rear face 20'~ which lS~ of~comp;lementary concave shape to the face ~21'. Thls arrangement~permlts the use of a cutter bit having a~siDgle ~cutting edgeJ or (as~shown in F~g. 6) a~cutter blt 11' having; tVO CUttillg edges 12 ., ~ . .

,, ,,, , ,:: , -,, ~ ,.

7~28~

and 12~. The cutter bit 11' is of symmetrical construction with respect to its median plane 31. Thus, the cutting edges 12 and 12' and the faces 20' and 22 are d:isposed syrnmetric~lly with respect to the plane 31.
In the assembled position, t~le rear face 20' of the cutter bit 11~ is supported by the convex support face 21' defined by the end wall 14'of the holder 109, and the front face 22 of the cutter bit is supported by the wedge 23. Because of its s~nrnetrical shape, the cutter bit 11' can also be inserted into the holder 109 so that its face 20' is supported by the wedge 23, and its face 22 is supported by the face 21' of the end wall 14'.
In either case, the po.inted end portlon 19' deflned by the face 20' (or 22) and the;base 32 of the~cutter~blt ll~ constltutes a pro~ectlon~. When ~the~;cutter bit 11 is inserted into the pocket 13 of the holder 10~, one of the portl~ons:l~9'~eng.~ges ~the lowe~ po~tion~of the~
: convex face 21~ of~the~holder end~wall:~l4~ thereby~
:~ preventing~the cutter bit;ll' from~falling out o the pocket.~ In other wor-s,~ the~pointed~ ~d~p~ort~ors~l9' ; fulfill the s~ne func~ion~as Lhe~pro~ectlon 19 of the cutter bit~ll of the embodirnent of:Flgs. 1 to~ 5~. ~
Figs.~7 and 8 show another modified form of cutter bit assembly:having a ilolder 10" and a cutter ~ .

~ ~7(~8~

bit 11". This assernbly is also sirnilar to that of Figs. 1 to 5, so like reference n~nerals have been used for llke parts, and only the modified parts ~
be described iTl detail. The main clifference between this embodiment and that of ~igs. 1 to 5 is that the rear cutter bit support face (that is to say the support face positioned in the region of the end wall 14" of the holder 10") is constitutecl by a cylindrical rod 33. The t~o ends of the rod ~3 are held in correspondingly-shaped apertures 34 fo~ned ln the opposite side walls35 of the holder 10", and the rod ;.s supportcd by a concave. part-cylindrical supl)o-rt face 36 ormed in the end wall 14". The rear end portion of the cutter blt 11"
is formed with a concave, part-cylindrical support face 20" which bears against the rod 33 when the cutter bit is fully inserted into the holder 10". The support face ~;~ ; 20" eng~ges the r~od 33 over all arc of approxirrlately 160 to 180. I,n this ernbodiment, the curved face 20"
deflnes a projection 19" wi~th~the~base af~the cutter bit 11". Thls~projection 19"~is e~quivalent to the~
projec~ion l9 of the embodiment~of Figs. 1 to 5, and engages behlnd the lower curved portion of~the rod 33, thereby proventing the cutter bit ll"~from falllng out f the holder 10".

~ .
....... , ,. , . ~ - , , ,, - .-. :

.' ' ~ ' .. ' , ' : ' . ' . ~
, , l ~ 70~84 The holder 10" is preferably produced by casting, whereas the rod 33 is preferably rnade of stainless steel.
The rod 33 is, advantageously, arranged to be a press fit within the apertures 34. Although the holder 10"
is intended primarily for use with a cutter bit held in position by the arcuate wedge ~3, it could also be used with a cutter bit which llses other forms of fixing.

:

, ~: ::

' ~, .

.

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:-

1. A cutter bit assembly comprising a holder and a cutter bit, the holder being formed with a pocket into which the cutter bit is mounted, wherein the cutter bit is retained within the pocket by means of an arcuate wedge positioned in a gap formed between respective curved support faces formed on the cutter bit and the holder.

2. An assembly according to claim 1, wherein the curved support faces are formed at respective first ends of the cutter bit and the holder.

3. An assembly according to claim 2, wherein the cutter bit is formed with a projection which engages with a complementarily-shaped portion of the holder to help retain the cutter bit within the pocket, the projection and the complementarily-shaped portion being formed on respective end portions of the cutter bit and the holder remote from said first ends.

4. An assembly according to claim 2, wherein the cutter bit support face is concave and the holder support face is convex.

5. An assembly according to claim 4, wherein the centres of curvature of the two support faces are offset from one another, so that, when the cutter bit is fully inserted into the pocket, the support faces define a tapered gap.

6. An assembly according to claim 5, wherein the holder support face is formed on a web positioned at said first end of the holder.

7. An assembly according to claim 6, wherein the holder is formed with an aperture, the aperture being positioned adjacent to the web in such a manner that, when the cutter bit is fully inserted into the pocket, the arcuate wedge can be inserted through said aperture and into the gap between the curved support faces.

8. An assembly according to claim 1, wherein the curved support face of the holder extends over an arc of at least 130°.

9. An assembly according to claim 8, wherein the curved support face of the holder extends over an arc of between 150 and 170°.

10. An assembly according to claim 1, wherein the thin end portion of the arcuate wedge is of reduced cross-section, said reduced cross-section end portion having a thickness which is smaller than the width of the gap formed between the adjacent portions of the support faces when the cutter bit is fully inserted into the pocket.

11. An assembly according to claim 10, wherein said reduced cross-section end portion of the arcuate wedge is formed with at least one slot terminating at, and extending substantially at right-angles to, the free end of said portion.

12. An assembly according to claim 1, wherein the arcuate wedge extends over an arc which is at least 10° larger than the arc of the curved support face of the holder.

13. An assembly according to claim 4, wherein the end portions of the cutter bit and the holder remote from said first ends are formed with respective complementarily curved support surfaces, said support surfaces being engageable when the cutter bit id fully inserted into the pocket.

14. An assembly according to claim 13, wherein the cutter bit is provided with a concave support surface and the holder is provided with a convex support surface.

15. An assembly according to claim 14, wherein the cutter bit has a cutter bit body and at least one cutting edge, the cutter bit body being insertable into the pocket in the holder, and said at least one cutting edge being positioned outwardly of the pocket when the cutter bit body is fully inserted into the pocket.

16. An assembly according to claim 15, wherein the cutter bit has two cutting edges, the cutter bit being of symmetrical construction having its two cutter edges symmetrically disposed with respect to a median plane of the cutter body, and with its concave support face and its concave support surface symmetrically disposed with respect to said median plane.

17. An assembly according to claim 15, wherein a cylindrical rod associated with said end portion of the holder comprises the support surface of the holder.

18. An assembly according to claim 17, wherein the two ends of the cylindrical rod are held within complementarily-shaped apertures formed in the holder.

19. An assembly according to claim 18, wherein the two ends of the cylindrical rod are press-fitted into their apertures.

20. An assembly according to claim 17, wherein the cylindrical rod is supported by a cylindrical support surface formed in said end portion of the holder.

21. An assembly according to claim 17, wherein the holder is made by casting, and the cylindrical rod is made of stainless steel.