Pliers having greater holding force

A pair of pliers, comprising:

• an elongated shank;
• a substantially convex fixed jaw locked onto at least one end of the shank;
• a movable jaw pivotally mounted on the at least one end of the shank and movable relative to the fixed jaw;
• wherein
• the fixed jaw has a surface provided with a plurality of locking teeth;
• the movable jaw has a surface provided with a first toothed face and a second toothed face;
• the first toothed face of the movable jaw is provided with a plurality of first engaging teeth;
• the second toothed face of the movable jaw is provided with a plurality of second engaging teeth;
• a workpiece is clamped between the locking teeth of the fixed jaw, the first engaging teeth of the first toothed face of the movable jaw and the second engaging teeth of the second toothed face of the movable jaw;
• each of the locking teeth of the fixed jaw has an angle (D) ranged between 90° and 92°;
• each of the first engaging teeth of the first toothed face of the movable jaw has an angle (B) ranged between 93° and 97°;
• each of the second engaging teeth of the second toothed face of the movable jaw has an angle (B) ranged between 93° and 97°;
• a line (L1) passing apexes of the first engaging teeth of the first toothed face of the movable jaw and a line (L2) passing apexes of the second engaging teeth of the second toothed face of the movable jaw have an included angle (H) ranged between 134° and 136°;
• the apex of one of the locking teeth of the fixed jaw and the workpiece have a first contact point (P1) and a first tangent line (L3);
• the apex of one of the first engaging teeth of the first toothed face of the movable jaw and the workpiece have a second contact point (P2) and a second tangent line (L4);
• the apex of one of the second engaging teeth of the second toothed face of the movable jaw and the workpiece have a third contact point (P3) and a third tangent line (L5);
• a line (L6) passing the first contact point (P1) and a center (O) of the workpiece and a line (L8) passing the third contact point (P3) and the center (O) of the workpiece have an included angle (G) ranged between 160° and 176°;
• the first tangent line (L3) and a face of a contacting one of the locking teeth of the fixed jaw have an included angle (A) ranged between 37° and 45° to prevent the workpiece from being slipped from the fixed jaw due to a deformation of the workpiece;
• the second tangent line (L4) and a face of a contacting one of the first engaging teeth of the first toothed face of the movable jaw have an included angle (E) ranged between 40° and 55°;
• the third tangent line (L5) and a face of a contacting one of the second engaging teeth of the second toothed face of the movable jaw have an included angle (C) ranged between 45° and 60°;
• the first contact point (P1) of the locking teeth of the fixed jaw and the second contact point (P2) of the first engaging teeth of the first toothed face of the movable jaw have a larger friction with a surface of the workpiece by a special angle design of the fixed jaw and the movable jaw to enhance a clamping force of the fixed jaw and the movable jaw on the surface of the workpiece, so that the workpiece is clamped by the fixed jaw and the movable jaw exactly and closely;
• each of the locking teeth of the fixed jaw, the first engaging teeth and the second engaging teeth of the movable jaw is designed to have an obtuse angle to enhance the strength of the locking teeth, the first engaging teeth and the second engaging teeth.