CA2054760A1 - Bottom blade for grass cutting unit - Google Patents

Abstract

ABSTRACT

A wedge-shaped blade/block assembly for a reel-type grass cutter has a tongue (56) in the blade (50) engaging a groove (68) in the bottom block. Abutments (58,60,70,72) above and below the tongue (56) resist vertical forces on the cutting edge (54). A series of generally horizontal bolts acting through the tongue (56) and groove (68) hold the blade firmly in engagement with the bottom block yet permit ready replacement of the blade when worn.

Description

k . ~ r ' ---i~ 711 ~ - ^' 130TTOM BI~ E R ~R4SS ~U1'2INC~ u~Lr ~ ~ ~j 4 7 ~ n ., ~ a3 ,, ,, ~
rhis i3~vention relates tt~ gras~ cu~ting uniCs of the t~pe havin~ ~
a ro~a~ing cut~er reel ~nd is hlore pa~cul~rlY concer~ted wit~ .
bot~o~ bla;de Fo~ use in such a c:utt~ng urlit.
A con~iaon bot~om bloclc a~%embly comprises ~ sub~ta~tial botto~ ,t~; :
bloclc o~ gle section to which 1~3 bolted a bo~tom bl~de in the f'or~ ,;jt , o~ relativ~ly th~n ~;trlp~ Typi~all~, thc blade is b~lted to the bottc1m 4,',~
blc)clc fro~ b~neath and ext~nd~ forwardly ~o nn upturned lip ~hich J~
provides ~he cutt~ng edgeA ~his arrange~nt, although co~mon~ ha~ a ~ i number of gi~nificant d~awbacks. Wi~h ~ pr7rtion of the rela~fvely ~hin .
blade ~fectively cantile~eL~ed forw~rdly of the bottom block7~ there is~
ten~e~cy ~or the blade cutting ~d~ to deflect vertic~ 7~ Up~ard deflectlo~ can lead to pre~ature ~ea~ of the ~o~tom blade and cu~ter $
reel whil~ downwa~d de~lection ca~8es the cu-tting unit to jam more . .
easily. It h~ been proposed ~o add sti~fening pi~ces to the b~tom .
block asse~bly, but this has not b~e~ to~all~7~7~atisfactc7r~. It has .'~
further ~ n.proposed to fo~ th~ bott~ blade inte~r~lly ~lth the .
bottom blo~k, but since thei bottom bl~d~ re~uires periodic r~placement .~ ~?i, :~
on ~ea~, an inteer~l arrangemen~ is too Costly ~nless very ~hin ~ ~r 9 sectia~s ar~ used for ~he bottom blo~k, in h~hicb ~ase the problem o~ .r~. .
lack o~ r~gidity is e.~ac~rba~ed. . ~;;.
I~ is a f~rther proble~ with cert~ no~m designs tha~ the b~l~s !;i secur~ng the bottom blade t~ ~he blo~k ~e positioned flush ~i~h the botto~ surf~ce of the blade. ~t is accor~ingly dir~icult tO achieve ~ i: `
ood purchase ~n the bolt ~or ~emoval, Qnd ~nfastening th~ bolt~ ca~ ,',7,, b~ a t~d~ou~ process, particularly i~ nificant wear has oc~ur~ed.
I~ læ a~ oba~ct of this invention ~o p~ovide an improved botto~ J
block a~se~bly ~or a ~ra~s cut~i~g ~nit in which de~lection o~ th~
cutting ed~e ~s c~n~iderably red~ced.
rth~r object ~f this inv~n~ion to provide a~ i~p~oY~d .` '`;i .`~
bot~o~ block 8s8embly in wh~ch the bl~de and bottom block as~ h~ld : r rigidl~ ~o~o~her in ~s~ but ç~n ~e re~di~y separated ~he~ ~ w~nn .
b~t~o~ b~ade hs~ to be ~epl~ced. . r~

r ~ ; rt 6 ~
.~ cco~l~ the preserlt lnventio~ CoDsiSts in a bt~tto~ ~lock .s a~sembly ~o~ a grass c~ltting ~it havin~ ~ rotating cuttf~r reel, the .
a~se~bl~r co~p~i~ing an elongat~ bottom block a~pted for mountin~ 't' '~
horizc~n~tly in the g~ass cut~ciLng unit an~ ~n elong~te blade seo~red ^ At to the l;~m block and adap~d in use to preses~t a t~ansverse cutti~g~
edge f~ oope~ation ~qith the rotating ~e~; wherein the blade ,~
co~p~ises a ~lcened moun~ing portior~ ote fro~ the cutt~ ed~
; s~ po~tion p~oviding ~irs~ and secon~ de abutinents spaced in a t ' '-' gener~lly ~e~tlc~l direction and each ex~ending along the length of .. the blade, ~herein th~ bottom block is provided with ~i~st and second .; bloc~ abut~ents po~itioned ~r eog~ge~ent ~ith the respecti~ blade . nbut~ents ~nd wherein f~s~ene~ me~ns ~re provided whi~h act al~ng a ; line e~ten ~ between the blade abut~ents to d~nw togethe~ the blade; ,~
and the bok3~ block, Pre~e~bl~ the blade and ~e bo~o~ bloc~ ~re provided ~ith ;~
re~pective c`~mplement~ril~ engagin~ p~t~ servi~6 to pravent rslative i r ~r~
3 d~plac~ent i~ a generally ~rtical di~c~ion. t ,.'~
Suit~bly, ~aid comple~ent~rily eng~ par~s co~prise J~
' ~' re$pec'c~veily ~ tongue and ~ ~oov~
Ad~a~tageo~sl~, thc bl~le and ~he botto~ block pres~nt s~ooth ~ upper su~ es wl~ich ar~ contiguo~s. ;;;
.; ~ae ~ ion will now ~e descr~.~ed by way o~ exawPle w~th . .~ ? ~k .~, r~f~ n~e .t~, the ~ccompanyin~ drawi~ in which:- r Fi~e i :l~ a perspec~:lv~ vie~,1 of~ a first botto~ block ~ssen~ly !
, according ~o the p~ior ar~
.~ , Fi~, ~2 i5 i3. persp9~:'cive vie~ ~ a ~econd bot~com block ass~bly~
'. ; eLcco~ g; tO the prior ~t, ,.,Xti~
. Flg~re 3 is a pe~spec~ve vie~,r o~ ~ botto~ blook asse~ly ~ ~?~
. ~i acco~ ~b ~e prei~ent inv~ntion ~d, 4 is a transvQ~se section on ~he bot~ block ~ssembly Fi~ure 3 - . ~ere ~: ~hown isl Fi~re 1 a co~ntis~nal ~ottom block asse~bly :~
h~ving a bottom block 10 of sub~ gle cross fiection a~d a bottom bl~e 12 in ~he f'or~ ~ a ~ela'cively ~hin striP. ~e blade i~
~ecu~ed to a ~tto~ block th~o~,gh sc~, ~vet~ or c~ther su~table A' ~ ~ P
fa~ten~. de~es at ~che locations sho~n at ~4~ The for~a~d por~ion oP ~ ~

I

''~Y3l ~ 3 - 2 0 5 ~7 G 0 ~
. th~ bl~de i~ for~ed wi~h a lip servin~ ~ produce a transverse cut~ln~
edge 16 ~o~ c~peratic,n with the cutter ~eel. In ~ltçrnative "; constru~tio~s~ h ~uttin~ ~dg~ ~,f appropriate l~nd width ~n b~ defined .
; ;j; in a gener~lly flat blade by ~ tr?3nsverse grwve spaeed a siho~t .
; ,-; dl~tance ~ the blad~ edge~ ~ t' .
.. ,~, ~n al~ër~kive know~ con~Cc~uctiOn i~ shown ~n Figure 2. In ~hi ;~ case, ~he assembly is fvrmed intqgr~lly ~ elatively thin ~teri~ ,.
; de~ining a.bla~e 18 h~ving a ~ ing e~g~ 20 and a block 2z o~
. t~ian~ seç~io~. To provld~ f~ness, a ~ille~ pla~e 24 i.~ ~.
someti~s ih~ert~d a~ the ba~e of the blo~k 22., . ~ .
;! ~ Bo~h ~he degcribed k~,town constructio~ su~r ~rvm th~ ~ .. ~.~ ;.
.~ disadvant~2 ~ha~ ~he cuttin~ ~dge is pro~ided on a relatively ~hin ,~
blade which i~ cantile~ered ~ro~ a tr~nsve~te llne oF ~upport. I~ the ' .
Figure 1 ct~os~r~ction, it will be recognlsed th~t the bl~tle 12 c~n be , ,t deflected ~p*ardl~ about ~he toe 2~ of the botto~ block and ~ownw~rdly;
, about the ~ne de~ined b~ f~st~ning locnt~ons 14. In the c~se o~ the Figure 2 ~rrsnge~ent, ~pward and downt~ard defle~io~ can oc~r abou~
t........... the ~r~nsvër8e li~e 28 sep~a~ing ~he blade 18 ~nd the block 2~ ~

.r .~ A~ has been men~ioncd pr~iou~ly, vertical d~lection o~ the i ~ i cutting edge Can s~riou~ly ~duce cut~in~ performance. ~,2j~
., Turnln~ now to Fig~r~ 3 ~nd 4, eher~ is illus~rated an i,~p~o~ed ; , ;~ botto~ bk a~sembl~ ~cco~din~ to th~ ihv~ntion. ~i ~"
.~ ~he b~o~ bl~de 50 ~ of gener~lly tri~ngular section ha~ing sti~
~ -. the apex ~ uptu~ned lip 5~ prov~din~ a c~ting edge 54. ~he base o~
i r"; ' the tr~ sect~ton is formed with ~ tDngue 56 e~te~di~ .r~.l .. i .; ~. lon~itudi~ y o~ the blade ~nd deli~ing ~n upper blad~ ~butment . e~
.~ qr~ac~ 5~ ~nd Q lower ~lade ~but~ent ~ur~ce ~0. These ab~t~ent ! ; ` sur~aces ~e ~ener~lly co~pla~ar and ~re inclined at a slight an~le t~ : t, -~
~; , the v*~t~e~ t interval~ ng the l~ng~h~ the bottom blad~ is, ~ provided ~ith threa~ed bllnd ~per~u~es 6~ which ex~end thr~ugh the !. '~
1~ T?~ to~gue 56~ . ; .. ~
The ~o~om bl~ck 64 h~ a tr~nc8~ed ~rian~lar sectîon with n cen~al v~id 6~. The ~or~ar~ edge o~ the block ls pr~ided ~ith a ~
groo~e ~8 sepRrating upper aDd lower ~ k 8~ut~en~ surfaCe~ 70 and 72 re~pe~t~Ye~y. As is ~h~wn in the drau~nge, ~h~ ~r~ove ~8 ~d block , '71~
t~ "~:' ,~;',;~, ; ' :,'~-~`
. , , . . ~ .

~ - 4 - ~3 i~ 3, 7 ~3 D ~

abutment sU~ces ïO, 7Z are ~haped and di~el~sioned so as to provid~ a' i-~
eomple~ent~r~ e~gage~ent with the ton~ue 56 and blade abu~m~nt ~. ~;
sur~ace~ 58,-~9 0~ the botto~ bl~de. .............................................. :~
P~i~3 o~ ~pertu~es 74 And 76 are pr~vid~d in t~e botto~ block and aligned ~l~h ~he r~pective blind aper~ur8s fi2 in ~he bottom blade. A ~
series of bol~s 78 extend Wh~ w gh these ~pertur~s and threadlly eng~ge' th~ bo~to~ ~lade so ~s to draw togsther the blade and bot~o~ block. I~' ~ r',i will be noted ~h~t in the regio~ of tlle head Or bol~ 7~, the bot~o~
block 64 iS re~essed to provlde ready n~ce~s to ~he bolt.
A~ the ~hiekne3~ o~ the ~lade incren~es pr~gressive1y fr~m ~he . ~ ~.
cutt~ng ~dB~ 54 tow~rd~ the b~to~ blo¢k ~4, ~he rigidity o~ the bl~de ~.
i~ signi~i~antly incr~ased. ~ore~ver, ~he ~ertic~l spacing ~ the ;
mating abut~ent surfaces ~n th~ blade ~nd bo~tom block together wi~h the tensi~n in the bolt 78 acting gener~ horizontally, p~avide sub~tanti~l res~st~ce to ver~ical de~lection o~ the blado ~elative th~ bl~ek. Thus a do~nw~rd ~OrCQ W a~ ~he cutting ed~e 54 w~ll be resi.~ted ~ ten~ion in the b~l~ 78 an~ engagement be~wecn ub~t~e~
sur~ace~ 60 ~nd 72 whilst Q~ ~pward force P will be resisted by ~he ; -~
bolt ten~lon and e~gagem~t between ~but~ent sur~ces 5~ and 70. ~' Becau$e the ~otto~ bloek assemblg~ according to th~s inveneion i~genersl~ d~e shap~d, opti~u~ use can be made of the a~,~ilable sp~c~5 between the euttin~ ~el ~nd gro~nd ~v as to g~e ~axi~um r~idi~g ~n ,.
'che ~s6e~bly both ~o~sionally and in bend. The smooth and conti~uo~S
upper surface~ o~ ~he blade and of the block also pro~ote ef~cien~ ~.
dl~chargalo~ cut g~a3s~
Main~e~ance procedure~ ar~ simplified in a numb~r Or respec~s~
Sl~e the bot~o~ bl~de is o~ in~reas~d ~nher~t sti~ness as co~p~red' to bl~aes; ~or example, as shown i~ Fi~ure 1, it becomes p~s~ible to ' use ~ewer f~tener de~ice~. Since ~he ~astener devices e.ttend gener~lly horizon~ , tha~ is to ~y a~ an ~ngle to t}~e horiz~ntal ~ ~ . i o~ le~ ~ha~ 45 ~d prefbrably 30 dr less, they ~o not n~d ~o '; ~ ~ ~ ~
be ~inish~d ~sh wi~h the underside o~ ~he ~ssembly. A mor~ pos~tive ~ ~; . :
p~r~h~e o~ th~ref~re b~ pro~ided. Noreover, the~e i~ no posgibili~ ~ .
of th~ h~ad o~ the bolt o~ o~her ~a~ene~ being ~orn thro~gh conta~
w~th tb~ g~ d, the~eby fur~le~ in~rea~ing the diF~iculti~ o~ ' 3~'r~ov~ s~

` 4 s;. .~
~ i Q ' I

I~~ 5 ~ 2 0 ~ ~ 7 ~
The t~g4e anr~ grc~ve f`or~ ions ~n ~h~ blade and botto~ bloc~ . . .
~5~1L'V'd ~he ~erbl purpv~e of p~rv idin~ ~ po~:iti~ k4~r . Thi R pre~nts ~ny displaee~ent durin~ U5* in ~he ve~tic~l dirs~tion and can also serve on asse~bly of the blad~ and bo~ block to st~aighten ouc any '. ,~
minor dist~r~ions in the bo~o~ blade. It will be und~rstoo~ that the ~ ~:`3 positian3 oF the tongu~ ~nd 6roove can be reversed. whils~ ~th~r complement~ry ~ormations could be employ~d, l~us a so~ries o~
proj~tln~ d~els could s~rve the same purpo~e or, ~ith appr~priately . -close tolerences. the bol~ 78 could ~erv~ additionally as locat~ng .;~
el ments. I~ ~ppropriate csse~, there need be no such comple~entQr~lY
eng~ging p~r~s ~erving to pre~en~ ve~t~cal displsce~en~, with th~ ~WD ~;;,?3,~~l~d~ ~bu~he~t~ ~hen b~in~ ~ontiguous and sim~larly the two b~oc~
abutments.,, ' ', ~ 'fL;'i~ .

': ~ ' ' ' " ' ' ' .'.':~

' ~' ' . , ,~J!~

(~

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Claims (8)

1. A bottom block assembly for a grass cutting unit having a rotating cutter reel, the assembly comprising an elongate bottom block adapted for mounting horizontally in the grass cutting unit and an elongate blade secured to the bottom block and adapted in use to present a transverse cutting edge for cooperation with the rotating reel; wherein the blade comprises a thickened mounting portion remote from the cutting edge, said portion providing first and second blade abutments spaced in a generally vertical direction and each extending along the length of the blade, wherein the bottom block is provided with first and second block abutments positioned for engagement with the respective blade abutments and wherein fastener means are provided which act along a line extending between the blade abutments to draw together the blade and the bottom block.

2. A block assembly as claimed in Claim 1, wherein the blade and the bottom block are provided with respective complementarily engaging parts serving to prevent relative displacement in a generally vertical direction.

3. A block assembly as claimed in Claim 2, wherein said complementarily engaging parts comprise respectively a tongue and a groove.

4. A block assembly as claimed in Claim 3, wherein said line of action of the fastener means passes through said tongue and said groove.

5. A block assembly as claimed in any one of the preceding claims, wherein said fastener means comprise a plurality of screw threaded fasteners spaced longitudinally of the assembly and each acting along a line inclined at less than 45° to the horizontal.

6. A block assembly as claimed in Claim 6, wherein said line is inclined at 30° or less to the horizontal.

7. A block assembly as claimed in any one of the preceding claims, being of wedge form.

8. A block assembly as claimed in any one of the preceding claims, wherein the blade and the bottom block present smooth upper surfaces which are contiguous.