ECCENTRICALLY SUPPORTED TOOLS FOR EXCAVATING MINERALS, COUNTERBALANCED WITH REFERENCE TO COUNTERWEIGHTS

OUTILS EXCENTRES POUR L'EXCAVATION DES MINERAIS AVEC CONTREPOIDS

English Abstract

ABSTRACT
A propelled eccentric drive for superimposing a percussive action onto drilling,milling, ripping and compacting operations having tools which are
compensated/counterbalanced with reference to predetermined
counterweights.

Claims

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THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. An assembly for drilling, milling, ripping and/or compacting materials
which includes a tool on a rotatable carrier connected to an eccentric
drive, the mass of the tool being compensated with reference to a
predetermined counterweight on the eccentric drive.
2. An assembly according to claim 1 in which the combined mass of the tool
together with an associated carrier is compensated with reference to the
predetermined counterweight.
3. An assembly according to claim 1 or claim 2 in which the tool for drilling,
milling, ripping and/or compacting is interchangeable with a similar tool
having its mass compensated with reference to the predetermined
counterweight before installation.
4. An assembly for drilling, milling, ripping and/or compacting materials
which includes a rotatable tool on an eccentric drive in which the degree of
oscillation by the tool is adjustable in relation to a fixed reference point.
5. An assembly according to claim 4 in which the tool is both radially and
tangentially adjustable in relation to the reference point.
6. An assembly according to claim 4 or claim 5 in which the mass of the tool
is compensated with reference to a predetermined counterweight on the
eccentric drive.
7. A method of balancing an assembly for drilling, milling, ripping and/or
compacting materials by means of a tool mounted on an eccentric drive,
which includes the step of compensating the mass of the tool with
reference to a predetermined counterweight on the eccentric drive.
8. A method according to claim 7 in which the tool is dynamically balanced.

Description

2~l~8~ ~
DE5CPIIPTION OF SYSTEM AND 17~A~INGS
V3rious Syst~ms exiSt for superimposing a percussive action on tools for use in
drilling, milling, ripping and similar operations. l~ese have th~ ~eneral
advantage that they requlre a minimal forward thrust during use, making them
considerably li0ht~r and mor~ sconomical to use than machines ~ormerly us~d
f~r the same purpose~ The pres~nt invention, d~erib~d with rr~ference to
diagrammatic illlJstra~ions only, has the si~nific~nt advantage tl~at
counterweights for counterb~lsncing the eccentrically driven tools on which ths
perGussive a~tion is suparimposed ns~d not be adJusted, se~ ~r corr~ted ~lh
r~fer0nce to th~ tools, which is generally difficult on site. The tools th~mselv~s
are compensated instead, wlth r~f~rance to the assem~y on which they are
~nstalled, and m~re particularly with raference ~o th3 counte~eiglrts ~f th~
assembly.
1 he as8embly may incl~de a rapidly rotatabl~, eccentric drive shaft for
producing th~ r~quir~d superimposed petcu~siv~ forc~s, the shaR being
optionally supported by a sin~le b~aring, or by a pair of bearin~s. The tools ofthe assembly may be slowly, ~re~ly rot~table wi~hout additional propulsion, or
they may be separately propelled and slowly r~ta~bl~. A tool for use in an
assembly according to the inv~ntion may be constibJted by a singl~ or a split,
interchangeabl3 sl~ve. In other embodiments o~ the i~ention t~e sleeve may
constitute a carrier for separately interchang~abte twls.
An assembly aec~rding to the pr~s~nt invention is shown in ngure 1 WhiCh
includes a sl~ve having a diameter of 300mm and a width of 300mm, equipped
wi~h 20 to ~0 milling tools. The sleeve may b~ driv8n at 3000rpm by m8ans of a
motoi rated at between 4kW and SkW. A reducti~n y~a~ arrar~ement causes
the sl~8ve to rotate at ~pproximat~ly 1 50rpm while oscillating at ~n amplitude of

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5mm Th~ ntion allows other similar means of propulsion t~ be used. In a
furth~r ~mbodim~nt of ths invention (not illustrated~ the sleeve is rotat~bl0 a~appr~ximately 150rpm in opposition to th~ dir~ction of rotati~n of the eccentricdrive sha~t through frictional engagement ~etween the sle~ve and an adjacent
work area.
The scvere p~rcussi~ action by the rotatin~ tool at comparative~ small
applications of thrus~ is at~ributable to the hi~h r~ational speed of the
eccentrically m~unted tool mass. Count~rbalancin0 ~nsures smooth nJnning
conditions.
A compacting tool ac~or~ing to ~he inv~ntion may indud~ a cylindrical drum of
circular or triangular cross-section, the drurn havin~ planar suffaces in the la~ter
case.
A sleeve constituting a carrier for various tools may b~ provided for performingmillin~ or ripping op~rations in a single st~p, or in multipis steps. In yet a fur~her
emb~diment of the inventi~n (not illustrated) a rotata~le cutting disk may be
provid~d for working In ~xtremely hard rock formations whils ap,olying a thrust
~f s~veral hundred kilograrns only, compared to betw~en ZO ~nd 30 tonnes
required ~or ~ther pri~r machinery. The ass~mbii~s d4scrib~d above g~n~raliy
operat~ whil6 transferring or no vibration to the machine propelling the
rotat~ble tooi. Even quartzitic and oth~r hard rock may be mill~d in this mannerwi~hout ad~itional cooling.
The assernbly shown in fl~ure :2 and defined in clairn~ 4 an~ 5 has the ~naral
advantage that no s~parats propulsi~n for tools intendcd for use in millin0
ope~ations is rsquir~d. More particularly the cutting paths ~ ind~idual tools ar~
adjustabl0 for cutting greater ~epths into mason~, for e2wnple, witho~
ad~usting the eccentricity of an associated tool c~rrier.
Fi~ure ~ shows ons of several possibl~ embodiments o~ the ir~n~;~n, in wh~h
referenc~ n~lmeral 1 denotes a drivs motor which propels an ecc~ntric drive
sha~t ~ which is supported on two bearings 3. A r~duction ge~r arrangement 4,
which incl~Jdes an internally toothed ring ~ear m~shing with a pinion connectsd
to ~he motor 1 is provided for rotatin~ a tool c~rri~r 5 at a slower speed than th0
shaft 2. Th~ tool carrier 5 is support~d on th~ eccentric drive sh~ Z by means
. . . . , . . . ., ~ . . ..

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of bearings 6, and is freely rotatabl~ about lhe shaft. Re~erence numeral 7
denotes the central axis of the eccentriG port~on of the driY~ shaft 2. Referen~e
numeral 8 d~not~s a s0~ of pra-sat count~ i0hts s~cur~d t~ th~ shaft ~. In the
presen~ embodiment o~ th~ inv~ntion th~ mass of ~ slidabiy locatabl~,
replaceabl~ sleeve 9, equipped with tools 10 and ~ in9 means, is
compansat~d with reference to the count~rweights 8 b~fors bsing mounted on
the carrier 5.
I:)ynamic balancing of the tooJs before installation on the eccentric drive is
d~sirabl~ to minimis~ any stresses acting on the bearings mentioned above
over ~xtended operating int~rvsls whila k~epin~ ener~y demands as low as
possibl~. .
In flg~lre 2 reference nurneral 11 denotes a milling tool for us0 in ripping or
planin~ operations. A bolt 12 or a similar fastening device is slide~ble in a slot
13 in the tool 11, and in its unsecured c~n~ition is displacsabl~ in relation to the
tool. When the ~olt 12 is position~d as shown in figure 2 the tool 11 produces
th~ small~st possible radial displacemen~ of th0 t~eth 15 during operati~n. On
the other h~nd when the bolt 12 is pos~ioned at the point i~nt~ d by reference
numeral 14 the r~dial amplitude of the oscillatin~ t~th 15 during operation is
maximised. Reference numeral 16 identrfi~s ths centrai axis of an eocentric
drivs shaR corresp~nding to the shaft 2 in figure 1, h~ving corr~sponding
counterwei~hts. A fix~cl ref~rance point for the purposes of adjustin~ the tool
11 may be located o~Jtside th~ spaG~ occupi~d by the tool itself, particularly if
the to~l is semi-circular or oth~rwiss shaped f~r the purposes ~ saving space.
The bolt 12 may ~llow r~dial and tangential displacement in relation to ths shaft
16. The assembly of figure 2 m~y b~ ad~pted for u~e in compact;ng operations
by providing means for propellin~ a tool ~orresponding to the tool 11 in a
gorward direction at optionally variable speeds.
Refer~nce numeral 16 serves to idant`fy an eccentric drive shaR corresponding
to that shown in fi~ure 1, while excludin~ the driv~ motor 1. The balt 1~ as
shown in figura 2, and at the position indioated by reference numeral 14, shows
the allowable range of adjustment f~r th~ cutting t~eth 15, bearing in mind thatths bolt 12 may be secured b~tween ei~er of thes~ extremes while located in
the slot 13. By option~liy adjusting ths tool 11 in a t~n~ential direction the
ds~r~e ~f ~scillation by th~ tools 15 may b~ further modi~ied. Thls may ser.~ to~chi~v~ a desir0d oscillation wh~n a machine equipped with the tools 15

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opsratcs from a stationary location. By setting th~ bolt 12 in the pos~ion shownin flgure 2 ~hs cu~ting t~sth 15 d~scrib~ small circular paths 12a whe~eas the
t~eth descri~ lar~sr cuttins paths 14a when the bolt 12 i~ located in ths
~orresponding position 14. Thc amplitud~ of oscill~t;ons d~scrib~d by th~ axis
7 ~emains unaffected.

Representative Drawing