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  • TPHCM, THANG 9/2009

  • Cac bc thc hin giai mt bai toan iu khin khi nen c banYu cu: Thit k mach iu khin khi nen hoat ng theo biu trang thai sau: u tin ta a phi vao. Khi tac ng vao nut nhn Start thi pittng A i ra tin hanh kep cht vi ap sut p = 5 bar. Khi kep u ap sut, pittng B dich chuyn ban may gia cng ranh. Sau o pittng B a ban may lui v va pittng A cung lui v thao chi tit ra.May phay ranh

  • Cac bc thc hin giai mt bai toan iu khin khi nen c banT yu cu hoat ng cua qui trinh cng ngh, ta thit lp c biu trang thai nh sau: Quan sat biu trang thai nhn thy:C cu chp hanh bao gm hai xy lanh A va B (tac dung kep). Cng tc hanh trinh S1, S2, S3, S4 c s dung xac inh vi tri cua cac xy lanh khi dui ra hay co lai. Cac cng tc hanh trinh nay chinh la cac van con ln.

    Xy lanh A

    S2

    S1

    Nhp thc hien

    Xy lanh B

    S4

    S3

    1

    2

    3

    4

    5 = 1

    Start

  • T hai kt qua nhn inh trn ta co c s nh hinh ve di y:La chon thit bi iu khin va c cu chp hanh

    S3

    S4

    B-

    B+

    R

    B

    A

    P

    S

    Xy lanh B

    S1

    S2

    A-

    A+

    R

    B

    A

    P

    S

    Xy lanh A

  • Bc tip theo cn phai xac inh cac iu kin xy lanh A, B dui ra va co lai. Tt ca chui hoat ng co 4 nhip thc hin, nhip th 5 trung vi nhip th nht co nghia la bc sang thc hin nhip th 5 la bt u lp lai qui trinh hoat ng, do o kt hp iu kin cua nhip 1 va nhip 5. Cu th, nhip 5 co cng tc hanh trinh S1 bi cham va nhip 1 la phai nhn nut Start: kt hp lai chinh la iu kin nhip th 1 c thc hin.

    Nhip 1: Xy lanh A dui ra vi iu kin A+ = Start ^ S1Xy lanh A dui ra cham vao cng tc hanh trinh S2: y chinh la iu kin nhip th hai c thc hin.Nhip 2: Xy lanh B dui ra vi iu kin B+ = S2Xy lanh B dui ra cham vao cng tc S4 tai cui hanh trinh: y chinh la iu kin nhip th 3 c thc hin.Nhip 3: Xy lanh B co laiB- = S4Xy lanh B co lai tac ng vao cng tc hanh trinh S3: y chinh la iu kin nhip th 4 c thc hin.Nhip 4: Xy lanh A co laiA - = S3

  • Ta tin hanh ni dy cho h thng iu khin trn:Ban u hai xy lanh A va B u co lai nn ca B cua van iu khin 5/2 ni vi ng cp khi cho xy lanh i v, ca A ni vi ng cp khi tac ng cho xy lanh i ra. Ca P ni vi ngun cp khi.Do hai xy lanh vi tri co lai tai thi im ban u nn hai cng tc hanh trinh (van con ln) S1 va S3 bi cham do o lam cho van ap lc 3/2 i vi tri, luc nay ca s 1 thng vi ca s 2 nh hinh ve minh hoa.

    50

    S3

    S4

  • Mach iu khin bng khi nen

    50

    S3

    S4

    B-

    B+

    R

    B

    A

    P

    S

    Xy lanh B

    S1

    S2

    A-

    A+

    R

    B

    A

    P

    S

    Xy lanh A

    1

    2

    3

    S4

    1

    2

    3

    S2

    1

    2

    3

    Start

    1

    2

    3

    S1

    1

    2

    3

    S3

  • PHNG PHP THIT K MCH IU KHIN KH NNCac phng phap thiet ke mach ieu khien bang kh nen co the giai quyet hau het cac van e trong ieu khien he thong kh nen.

    Cac phng phap thiet ke mach kh nen eu ap dung cac phng phap thiet ke so. Tuy nhien khong co mot phng phap nao toi u nhat, v moi phng phap eu co u iem va nhc iem rieng. Phng phap thiet ke theo tang Phng phap thiet ke theo nhp (tuan t)

  • PHNG PHAP THIET KE MACH IEU KHIEN THEO TANGThit k theo tng c coi phng phap c ng dung rng rai nht trong vic thit k khi nen trong ca 2 phng phap iu khin bng khi nen va in-khi nen vi co th d dang thc hin va hiu hoat ng cua mach. Nguyn tc thit k mach theo tngCach chia tng va xac inh tin hiu u tng Khai quat mach ao tngCac bc giai mt bai toan iu khin theo tng

  • Thit k mach iu khin theo tng la phng phap thit k thanh tng tng ring. mi tng hoan thanh mt hoc mt s bc cua chu ky iu khin. Trong thiet ke mach ieu khien theo tang can thoa man hai nguyen tac:Tn hieu vao cac bc trong cung mot tang khong c trung nhau. Do o khi co cac tn hieu vao giong nhau ta phai xet en viec chia tang. Tai thi iem bat ky ch co duy nhat mot tang ieu khien hoat ong. NGUYEN TAC THIET KE MACH THEO TANG

  • CACH CHIA TNG VA XAC INH TIN HIU U TNG Chia chu ky hoat ng cua cac c cu chp hanh thanh cac tng vi iu kin: Khng co xy lanh nao va i ra va i v trong mt tng hoc c cu quay va chuyn ng thun chiu va ngc chiu trong cung mt tng. A+ : xy lanh A i raA- : xy lanh A i v thi iu kin trong vic chia tng la khng co ky hiu cua mt xy lanh nao lp lai trong cung mt tng. Vi du: co 3 xy lanh A, B, C hoat ng tun t nh sau: Start, A+, B+ / B-, A-, C+ / C-Tng: I / II / III

  • A+A-B+B-

    S3

    S4

    B-

    B+

    R

    B

    A

    P

    S

    Xy lanh B

    S1

    S2

    A-

    A+

    R

    B

    A

    P

    S

    Xy lanh A

    Xy lanh A

    S2

    S1

    Nhp thc hien

    Xy lanh B

    S4

    S3

    1

    2

    3

    4

    5 = 1

    I

    II

    Tang

    Start

  • CACH CHIA TNG VA XAC INH TIN HIU U TNGAp dung cac nguyn tc chia tng nh nu trn: chui hoat ng cua hai xy lanh c chia lam 2 tng: tng I: A+, B+; tng II: B-, A-.

    Co th s dung vong tron chia thanh nhiu phn vic chia tng va xac inh tin hiu u tng c thun tin va d dang hn.

    Xy lanh A

    S2

    S1

    Nhp thc hien

    Xy lanh B

    S4

    S3

    1

    2

    3

    4

    5 = 1

    I

    II

    Tang

    Start

  • CACH CHIA TNGA+A-B+B-IIIIII

    Xy lanh A

    S2

    S1

    Nhp thc hien

    Xy lanh B

    S4

    S3

    1

    2

    3

    4

    5 = 1

    Start

  • CACH CHIA TNGA+B+B-A-IIIIIIC+C-

    Xy lanh C

    S6

    S5

    Xy lanh A

    S2

    S1

    Nhp thc hien

    Xy lanh B

    S4

    S3

    1

    2

    3

    4

    5

    Start

    7 = 1

    6

  • A+B+B-C+IIIIIIC-A-

    Xy lanh A

    S2

    S1

    Nhp thc hien

    Xy lanh B

    S4

    S3

    1

    2

    3

    4

    5

    Start

    Xy lanh C

    S6

    S5

    7 = 1

    6

  • CACH CHIA TNG VA XAC INH TIN HIU U TNGVic xac inh tin hiu u tng rt quan trong, cac tin hiu nay chinh la cac iu kin chuyn tng vi tai mt thi im chi c phep mt tng co khi.Cac tin hiu u tng thng la cac cng tc hanh trinh (van con ln i vi h thng iu khin bng khi nen). Tin hiu u tng n chinh la tin hiu cui cung c tac ng cua tng th n-1. Tin hiu u tng 1 chinh la tin hiu cui cung cua tng n kt hp vi nut nhn Start.

  • CACH CHIA TNG VA XAC INH TIN HIU U TNGTin hiu u tng I = tin hiu cui cung c tac ng cua tng 2 kt hp vi nut nhn Start.E1 = S1^ StartTin hiu u tng II = tin hiu cui cung c tac ng cua tng I.E2 = S4

    Xy lanh A

    S2

    S1

    Nhp thc hien

    Xy lanh B

    S4

    S3

    1

    2

    3

    4

    5 = 1

    I

    II

    Tang

    Start

  • KHAI QUAT MACH AO TNGNguyn tc hoat ng cua mach ao tng:Ban u, mach ao tng se cp khi cho tng th n.Sau khi nhn nut Start, mach ao tng se cp khi cho tng th I, tng nay, ngun khi se cung cp cho cac chuyn ng trong tng I iu khin c cu chp hanh (co th iu khin trc tip hoc thng qua cac cng tc hanh trinh).

    Tin hiu u tng II se c tac ng khi tng I kt thuc, tng II co khi va ngun khi nay cung cung cp cho cac chuyn ng trong tng II. Tin hiu u tng III se c tac ng khi tng II kt thuc, tng III co khi . Va c tip tuc nh th cho n tng th n, va chu trinh lai quay tr lai tng I.Mach ao tng: bao gm cac van ao tng (thc cht la cac van ao chiu 4/2 hoc 5/2 co duy tri).

  • MACH CHUN 2 TNG C BANS lng van ao chiu lun bng s tng tr i 1 Mach 2 tng (n=2), nh vy se co 1 (n-1 = 1) phn t nh. E1 la tin hiu u tng I, E2 la tin hiu u tng II.Ban u, khi t ngun se cung cp cho tng 2, sau khi co tin hiu E1 tac ng, van 5/2 i vi tri lam cho khi c dn ln cung cp cho tng I, khi tng II thoat ra ngoai.Mach chun 2 tng c ban

  • MACH CHUN 2 TNG C BANMach chun 2 tng vi cach ni dy cho cac tin hiu u tng

    50

  • MACH CHUN 3 TNG C BANMach 3 tng (n=3), nh vy se co 2 (n-1 = 2) phn t nh. E1 la tin hiu u tng I, E2 la tin hiu u tng II, E3 la tin hiu u tng III.

  • MACH CHUN 3 TNG C BANMach chun 3 tng vi cach ni dy cho cac tin hiu u tng

    50

  • MACH CHUN 4 TNG C BAN

  • MACH CHUN 4 TNG C BAN

    50

  • CAC BC GIAI MT BAI TOAN IU KHIN THEO TNG Bc 1: T yu cu cua h thng iu khin, ta xac inh cac bin cn thit la cac cng tc hanh trinh va vi tri lp t, cac cam bin cn thit s dung, cac nut nhn hay cn gat la chon (Start nut khi ng, Stop nut dng, iu khin t ng Auto hay bng tay Man).Bc 2: T quy trinh cng ngh, xy dng biu trang thai (biu din cac phn t trong mach, mi lin h gia cac phn t va trinh t chuyn mach cua cac phn t. Cu th xac inh co bao nhiu c cu chp hanh va trinh t hoat ng). Bc 3: Tin hanh vic chia tng, co th ghep cac tng lai vi nhau nhm muc ich ti u hoat ng cua h thng nhng phai am bao ung nguyn tc cua vic chia tng. Xac inh chui hoat ng co bao nhiu tng v cac tin hiu u tng tng ng.Bc 4: Lp quy trinh thc hin cho cac tng v cac bc trong tng. Xac inh cac iu kin cac c cu chp hanh hoat ng ng vi quy trinh thc hin trn. Bc 5: Thit k mach iu khin bng khi nen s dung cac mach ao tng chun nh trinh bay trn.

  • BI TP P DNGH thng iu khin may dp chi tit vi yu cu cng ngh nh sau: Xy lanh A thc hin cng vic dp chi tit va xy lanh B co nhim vu y san phm ra khoi khun (loi san phm). Chu ky hoat ng cua may dp nh sau:Ngi cng nhn a phi cn dp vao khun, sau o nhn cng tc hoat ng START.Xy lanh A dui ra va thc hin chuyn ng i xung dp chi tit.Sau khi dp xong chi tit thi xy lanh A co lai tr v vi tri ban u.Khi xy lanh A v vi tri ban u thi xy lanh B i ln y chi tit va dp ra khoi khun.V sau khi y xong chi tit thi xy lanh B quay tr v lai vi tri ban u.Chu k hoat ng kt thuc va mt chu ky k tip hoat ng Hoat ng cua may dp

  • Bc 1: Vi yu cu ra la iu khin 2 xy lanh A v B theo chu tr