17: Cong dung va ploai may cap? Trinh bay ctao chung cua may cap? Pham vi SD? Qua trinh lam viec cua may cap? Phan tich qua trinh dao dat vao thung cap? Nang suat may va cac BP nang cao nang suat may.

* Cong dung:

May cap lam nhiem vu dao va van chuyen dat nhu may ui, kha nang van chuyen dat xa hon may ui ma nang suat van cao. Chieu day lop dat cat tu 0,12 den 0,53m. Cu ly van chuyen doi voi may cap khong tu hanh tu 300 den 500 met, may cap tu hanh den 7500m.

Trong xay dung cac cong trinh dan dung, cong nghiep, giao thong van tai, thuy loi, may cap thuong duoc dung de dao va dap nen duong, xay dung san bay va van chuyen vat lieu voi khoi luong lon va tuong doi tap trung.

* Phan loai:

Phan loai may cap: Dang may cap keo theo hoac nua tu hanh; May cap tu hanh

May cap thuong duoc phan loai theo cac cach sau:

+ Theo hinh thuc di chuyen: may cap tu hanh, ban tu hanh va may cap khong tu hanh.

+ Theo dac diem cua bo di chuyen: loai banh xich va loai banh lop.

+ Theo dung tich thung chua: loai nho (toi 2,5 m3), loai trung binh (tu 2,5 den 10 m3), loai lon (> 10 m3).

+ Theo kha nang dua dat vao thung chua: loai tu do va loai cuong buc.

+ Theo phuong phap do dat: do dat tu do ve phia truoc va phia sau, do dat cuong buc va ban cuong buc, do dat qua khe ho.

+ Theo dac tinh thiet bi dieu khien: dieu khien bang co hoc, dieu khien bang thuy luc.

b. Cau tao va nguyen ly lam viec cua may cap

+ Loai may cap khong tu hanh:

Doi voi may nay co hai bo phan rieng biet: bo phan may keo va bo phan thung cap chuyen. De dieu khien bo phan thung cap co hinh thuc dieu khien co hoc (cap) va dieu khien bang thuy luc

+ May cap tu hanh (hinh 4-24)

Loai nay khac voi loai khong tu hanh o cho khong co bo phan dau keo tach rieng.

cau tao may cap tu hanh:1- Dau may keo MAZ-529E; 2- Truc do cang; 3- Cang quay; 4- Xy lanh thuy luc nang ha thung chua; 5- Cua dong mo; 6- Thung chua; 7- Thanh sau thung chua; 8- Xy lanh thuy luc mo cua thung chua; 9- Banh xe sau.

+ Qua trinh lam viec cua may cap.

Qua trinh lam viec cua may cap gom cac giai doan chu yeu sau:

- Giai doan dao-tich dat: thung cap duoc ha xuong nho he thong xi lanh thuy luc de luoi cat bap vao nen dat voi chieu day cat thich hop. May tiep tuc di chuyen ve phia truoc voi toc do cham, dat se duoc cat va tich vao thung. Khi da day dat, thung duoc nang len, nap thung dong lai.

- Giai doan van chuyen thuan tuy: may cap di chuyen voi toc do lon nhat tuy thuoc vao kieu may.

- Giai doan do va rai dat: nap thung duoc mo ra, thung cap ha thap xuong cho phu hop. Dat duoc day ra ngoai (voi may cap do cuong buc), neu la kieu do tu do thi thung cap se duoc nang len roi nghieng ve phia truoc hoac phia sau tuy thuoc vao cau tao cua thung.

Trong qua trinh ay, giai doan dao-tich dat vao thung chua la quan trong. No anh huong rat lon den nang suat cong tac.

Hinh 4-25. Chu ky cong tac may cap va qua trinh xa dat

1. Dau may keo co so; 2. Thung cap; 3. Nap trhung; 4. Khop cau; 5. Tam chan phia sau; 6. Cap dong mo lap thung; 7. Xi lanh nang ha thung; 8. Banh sau; 9. Luoi san; 10. Bang gat dat.

c. Thi cong bang may cap

+ Cach dao dat

Tuy theo moi loai dat dao ma co hinh thuc cat dat khac nhau (hinh 4.26). Luc dau an luoi cat den do sau toi da co the duoc, sau nang dan luoi cat len de phu hop voi suc keo cua may. Cach dao nay co cu ly cat dat la ngan nhat. Neu cung mot dieu kien thi cong thi cach dao dat nay cho nang suat cao hon ca.

+ Cac so do di chuyen:

Tuy theo dia hinh lam viec va tinh chat cua cong trinh ma co cac so do di chuyen trong qua trinh dao, van chuyen

- So do di chuyen hinh E-lip: khi dung may cap de dao kenh muong hoac xay dung cac cong trinh ma truc dao song song voi truc dap. Cach di chuyen theo so do nay, cu mot chu ky lam viec (dao-van chuyen- dap- quay ve noi dao) gan giong hinh E-lip. Theo so do nay

may cap phai quay may 1800 hai lan va bao gio cung di theo mot chieu, do do banh xe di chuyen thuong bi mon lech mot ben. Muon khac phuc nhuoc diem nay can thay doi luon huong van chuyen cua may cap

la giam duoc khoang 1520% thoi gian so voi so do hinh E -lip, dong thoi khong xay ra tinh trang bi mon lech mot ben cua banh xe.

- So do hinh chu chi (dich dac): voi cong trinh dao dap kenh muong chay dai, cac may cap co the noi duoi nhau chay doc cong trinh: dao-van chuyen-do dat theo so do chu chi.

d. Nang suat va bien phap nang cao nang suat cua may cap

+ Cach tinh nang suat cua may cap

Nang suat may cap lam viec trong 1 gio duoc thinh theo cong thuc:

m3/h

Trong do: q- dung tich thung xuc chuyen (m3);

kd- he so lam day thung;

kx- he so toi xop cua dat;

ktg- he so su dung thoi gian (ktg=0,85 0,90);

Tck- thoi gian mot chu ky lam viec (dao tich dat - van chuyen - do dat - quay ve noi dao, (giay).

Qua cong thuc tren ta thay: nang suat cua may cap phu thuoc vao he so lam day gau (kd) xac dinh qua ty so kd/ kx va phu thuoc vao thoi gian 1 chu ky lam viec cua may.

+ Nhung bien phap nang cao nang suat

Muon nang cao nang suat cua may cap truoc het can phai tang he so lam day thung (Kd) va rut ngan thoi gian mot chu ky (Tck) lam viec.

- Bo tri may cap khi dao dat tren duong xuoi doc tu 100 de loi dung them trong luong may va tang luc keo.

- Tuy theo loai dat ma co the ap dung cac hinh thuc cat dat (nhu noi o phan tren) de lam tang kha nang xuc duoc day thung.

- Tien hanh dao tich dat theo hinh thuc cai rang luoc (hinh 4-28). Theo cach nay, dat duoc dao theo tung ranh. Ranh no dao cach ranh kia bang chieu dai luoi cat chinh cua may cap. Luot dau tien (lan I) ranh dao bang toan bo luoi cat cua thung xuc chuyen, con cac lan sau (lan II, III...) mot nua quang duong dao thi luoi cat chinh lam viec va chi cat go dat do tao boi cac ranh dao lan truoc... Cach dao nay co the xuc day co ngon ma lai phu hop luc dao giam dan do cong suat dong co con phai phan phoi cho luc keo di chuyen ngay mot tang do tai trong tang.

Cung trong phuong phap dao, kinh nghiem cho thay: sau khi xuc dat vao thung chua chung 3040%,so vong quay cua dong co may keo giam xuong, ta se nang thung len ngay. Luc do dat bi tac va do trong luong rieng dat don ca lai phia thanh sau. Sau do lai tiep tuc ha thung xuong dao va lay them khoang 2030% dat nua thi lai nang thung len. Ta cu dao nhu vay 3, 4 lan thi day thung. Cach dao nay nang suat kha cao.

- Bo tri noi dao dat, noi do dat cho hop ly de viec dao va do duoc nhanh chong khong phai cho doi.

- Muon nang cao chi tieu lam viec cua may cap (ca ve mat kinh te va ky thuat) thi phai dung loai may co dung tich thung lon hon, pham vi van chuyen dat rong hon, khoi luong dao va dap lon hon. Dieu nay duoc xac lap tren bieu do tuong quan giua do dai van chuyen voi nang suat may cap