镐型截齿截槽非对称的峰值截割力计算

为了能够对平面截割截槽非对称条件下镐型截齿垂直截割煤岩时的峰值截割力P_c'进行预测,基于截槽非对称模型,通过理论推导得到了截割孔半径r、截深h_1,h_2及煤岩左、右崩裂角Φ_1,Φ_2关系的一般表达式。提出了r相对截深h_1,h_2可忽略时截槽对称的峰值截割力P_c的新的计算公式;基于截槽非对称与截槽对称条件下的峰值截割力与表面接触半径的等效概念,即通过换算等效截深hequ,并利用截槽对称的峰值截割力P_c推导得出了截槽非对称的峰值截割力P_c'计算公式。所得到的截槽非对称(h_1h_2=h)的镐型截齿垂直截割的峰值截割力P_c',能够考虑截齿半锥角θ、煤岩抗拉强度σ_t、脆性指数m以及齿岩摩擦因数f等参数对其的影响;在保持h_2=h不变的条件下,得到P_c'与h_1/h_2的变化近似呈线性关系的结果。理论计算结果得到了试验结果的验证。

Calculation of peak cutting force of conical picks under conditions of dissymmetrical slotting

In order to forecast the peak cutting force P′c of vertical cutting of conical picks under the conditions of plane cutting and dissymmetrical slotting (h1＜h2),the general formula of the relationship among the cutting hole radius r,the cutting depth h1 and h2,left burst angle Φ1 and right burst angle Φ2 of coal and rock are theoretically deduced based on dissymmetrical cutting model.When r is negligible compared to cutting depth h1 and h2,the new calculation formula of the peak cutting force Pc is first put forward under the condition of symmetrical slotting.And based on the equivalent peak cutting force and the surface contact radius under the conditions of symmetrical and the dissymmetrical slotting,through introducing the equivalent cutting depth h equ,the calculating formula of peak cutting force P′c under the condition of dissymmetrical slotting is derived with the aid of calculating formula of peak cutting force Pc under the condition of symmetrical slotting.The main conclusions are drawn that the peak cutting force P′c of vertical cutting of conical picks under the conditions of dissymmetrical slotting (h1＜h2=h) is related to half-cone angle θ of picks,the tensile strength σt and brittleness index m of coal and rock and friction coefficient f between picks and rocks,and also has a linear relationship with h1/h2 when keeping h2 constant (h2=h).The theoretical results are very close to the experimental results.