[SPECIFICATIONl
[Title of the invention]
Cutting insert having a corner recess
[Technical field]
The present invention relates to a cutting insert, more particulmly, to a cutting insert having a structure being capable of effectively controlling diips generated on a woik-piece at the time of paforming a cutting {»X)cess ftion and with effective heat dissipation is provided.
Due to the specific shape of the chip forming groove and a smooth tnmsiticm betweoi diffaioit portions of (he diip forming groove, however, an effective control of chip orientation dq)ends on the positioning of the cutting insot in the tool.
Under tiie above conditi(»is, the diips fonned by tiie cutting edge will be deflected in the ' direction toward, rather tiian away fiom the woik-piece due to the cutting insert posittmied in the tool at negative rake angles. Consequently, the woik-piece and (he tool may be damagdd by the chijps.
In particular, to machine mild steel noating dnps f/tidi are difficult to control ((hat is, not bait easily (he serrated fitting insot is required, hi addition, tte cutting insert which can remove &e daps easily and minimize a cuttii lotd wider the madiining o(Hidititrusiuiithed cm ti» cutting tool.
Detailed structure of tiie side cutting ece pcntimis 110, 120, 130 and 140 and tiie coma: cutting edge portions 210,220,230 and 240 of ttie otiting insot 100 ccMtructed as described above is desoibedbeiow. hi the descripticmbdow, for the sake ofconvenieno erne side cutting edge portion 130 and one comer cutting edge portion 230 are illustrated as an exane.
Comer gMftmg gjg ppniw
The coma-cutting edge portions 210,220,230 and 240 of the cutting insert 100 aconding to the present invention have the same configuration. FIG. 3 is a partial perspective view of "X" part in FIG. 2 and shows a structure of one comer fitting edge pcnticm 230.
And, FIG. 4 is a secticmal view taken along ttie line A-A in FIG. 2, and FIG. 3 and shows a section of one comer cutting edge p(ntion 230.
Tlie comer cutting edge portion 230 formed at an interaectiim p(n1ion of two adjacent side

cutting edge portions 130 and 140 has a comer cutting edge 231 formed at a fiont end Ihoieof. A land portion 232 and a comer bottom sur&ce 234 having a cotain width are sequoitially formed on an vtpper surface of an inside of the coma cutting edge 231. Tlie hdg of the comer bottom sur&ce 234 is smaller than that of the comer cutting edge 231, and the land p(»tion 232 and the ccnna* bottom sun&ce 234 are connected by a downward inclined surftce 233 fomied tiierebetweoi.
A first protrusion 236 having a cotain widfli is formed at an inno* side of the comer bottom sur&ce 234 toward the insert central hole. A height of Ae first jnotnision 236 is larger than tiiat of the comer bottom sur&ce 234, but is smaller than that of tiie comer cutting ed 231. On the othor hand, ttie first protrusion 236 and &e comer bottom sur&ce 234 are ccmnected by a first iq>ward inclined sur&ce 235.
A second i»Y)tnision 238 having a certain width is fimned at an inward side of the first protrusion 236. A height of the second protrusion 236 is larger dian that of the oomec cutting edge 231, A second iQ)ward inclined sur&ce 237 connects the first protnisicm 236 and the second protmsion 238. An iq)ward grooved sur&ce 239 connected to dK seating sur&ce 1A is fimned on at an inard side of the second protrusion 238.
Here, the land portion 232, the downward inclined sur&ce 233, (he comer bottom sur&ce 234, the first iq)ward inclined sur&ce 235, the first {nntnision 236, the second iqiward inclined sin&ce 237, the second protrusion 238 and the upward grooved sur&ce 239 are disposed sequentially on a diagonal line onssing the comer cutting edge 231 and a center potion of the cutting insert 100.
Si4 putting edgg portJQp
The side cutting edge pcMtion 130 formed at an ititersec(j<»i between the i>per sur&ce 1 and the side sur&ce 2 has a sen»ted shi fimned along the entire lengdi thereof
That is, raised portions and deiM«ssed p(»ti(»is are alteniativdyfinmed on an upper ni the side cutting ed portion 130 aloqg the entire lengdL Ihe seoaticm of the side cutting edge is obtained by the raised portions and the depressed pcntions finmed cm the upper side of the side cutting

edge portion 130,
A dail configuration of the above side cutting edge portion 130 is desoribed as follows.
FIG. 5 is a sectional view taken along the line B-B in FIG. 2 and sws a dq»es»ed pcntion formed on the side oitting edge portion 130. And, FIG. 6 is a secti(»ial view taken along line C-C in FIG. 2 and shoin a raised portion formed on the side oitting edge portion.
The side cutting edge descends and ascoids repeatedly stsarting fiom the comer cutting edge 231, and so the side cutting edge portion 130 has a serrated tapc in v/ladi dqnessed p and a h 131-2 of the raised portion 130-2 is equal to that that of the comer cutting edge (indicated by the dotted horizontal line in FIG. 6).
In the depressed portion 130-1, one that is adjacent to tiie comer cutting edge 231, fiirtfaer comprises an iq)ward indined sur&ce 136-1 and an extended |»otnision 137-1 disposed at tfie fimtt of the upward grooved sur&ce 135-1. Here, the extended protrusion 137-1 is extended frcnn the second

protrusion 238 of the coraei- cutting edge portion 230 in parallel to the side cutting edge 'l3l-l. However, the heit of the extmded protrusion 137-1 is snyaller than that of the d&aond protrusidn 238.
On the other hand, coma* lidges 240 are formed at botders of flie comer cutting ed 231 and the dejBiessed portion 130-1 adjacait to the comw cutting edge 231. H&e, eadi of flie comer rid] 240 is extoided from the side cutting edge 131-1 toward an inside and has the hdgjit equal to or smaller than tiiat of the side cutting edge 131-1 of the dquessed portion 130-1 and higher tiian that of tiie comer bottom sur&ce 234.
Here, it is preferable diat ooma ridg 240 is extended toward ttie first protrasion 236 of fhs coma-cutting edge portion 230 but is short of the first inotrusion 236 so that a gap is formed between e coma ridge 240 and the first {HOtcusion 236.
Below, function of ttie cutting insert according to ttte pteseat invention as le,,230 in FIG. 3), a dose-diied reoes is fomied by the comer cutting edge 231-1, tiie downward ijtidiaed sur&ce 233 adjwxnt to Hoc pomer cutting edge, the comer bottom sur&oe 234, the first piotrucm 236 extended to ajjcenter of (he cutting insert along the diag(»id line, and the ccmer ridges 240 extended fixun ends of tiie conr cutting ed 231-1 toward the first inotnision 236. Due to the above structure it is possible to control the dap effidmtly and mininoize a cutting load under the condition of a smaU depth of cut so that tfie 1 of the cutting insert can be increased. Preferably, at tiiis tim tiie first protiusiiHi 236 hia a hei largo: than fliat of the conur bottom sutfiice 234 by 0.01 mm to 0.05 nun.
The second trusion 238 exteiided in (he diagcnial direction of the cutting insert and having a heit larger than that of ttie first inx)tcusind i»otnMon 238 and exteotod in i»ralld to the idde cutting 131-1 or at an ang|le witii rented to the side cutting edge, The extonded pKrtnist(»i 137-1 htts a heigiht smaller.tfaan tfiat of the second prottusiward indined surfiice, a first protrusion, a second iq>wanl indined sur&oe, a xcond protrusion, an iq>ward grooved surfiice and the seating sur&ce are sequentially formed sequentially on the comer cutting edge p(xtion along a diagonal line directed fixnn the comer cutting edge to Ifae central hole, and
tiie coma- bottom sur&ce has tiie smallest height along the diagonal line.
[claim 2]
The cutting insot acconling to daim 1, iiviieridn the first protradcm has a hdg}
that of the comer cutting edge and the secoi protrusion has a 1 larger tiian that of pomer
cutting edge.
[Claims 3]
The cutting insert aoo(»ding to daim 1, wfaerdn the side G«rtting edge is repeatedly desoeiMled and ascended starting fix)m tiw corns cutting edge so &at tfie dde cutting e( have a serrated stu in wtddi raised portions and dqnessed portions are altemativdy disposed.
[claim4]
The cuttiiig insert acocHxitng to claim 3, wfaerdn the raised p(Mti(»s and the depressed of tiie side cutting edge are extended fixnn the side cutting edge toward an inside, and followed by a land portion, a downward indined sur&xs, a side bottcHn surftoe and an iq)wani grooved sac&oo disposed sequentially on tiie side cutting edge portion.

Claims 5
ITie culling insert according to claim 4, wherein the side bottom surface of the raised portion has a width larger than that of the side bottom surface of the depressed portion.
Claim 6
the cutting insert according to claim 4 or claim 6, wherein the depressed portion adjacent to llie corner cutting edge has an upward inclined surface and an extended protrusion disposed at the front of the upward grooved surface, and the extended protrusion is extended from the second protrusion in parallel to the side cutting edge and has the height smaller than that of the second protrusion.
: Claim 7
The cutting insert according to claim 4 or claim 6, wherein a corner ridge is formed at a border of the corner cutting edge and the depressed portion adjacent to the corner cutting edge, the corner ridge has the height equal to or smaller than that of the side cutting edge and higher than that of the corner bottom surface.
Claims 8
The cutting insert according to claim 7, wherein the corner ridge is extended toward the first protrusion but is short of the first protrusion to have a gap therebetween.