Standard twist drill is a very common drilling tool. It is simple, easy to grinding, but make it really good grinding, sharpening methods and techniques to master for beginners vocational school students, but also as easy matter. Factories have such a situation, the workers work more than ten years, less wear good twist. What is the reason? The key is the methods and techniques. The means to acquire, the problem will be solved. Students craft lesson already learned a standard twist-related knowledge, sharpening standard twist drill requires basically back down: ① angle of 118 ° ± 2 after 2º② hole edge angle α0 of 10 ° -14 ° ③ chisel edge angle is 50 ° -55 ° ④ two main cutting edge and the drill axis length and angle to form two equal ⑤ two main flank to grinding smooth. There is not enough light theory, we must allow students to stand before the grinder hands, hands blindly grinding. Hands-on guide students sharpening methods and techniques, so no matter how good the theoretical knowledge of students, you let him go first grinding a standard twist drill, in all likelihood are not drilling. Why? Theory has not yet serve as a guide for practice. Students have not mastered the skills and techniques sharpening. Common standard twist drill only two main flank grinding and grinding chisel edge, but after grinding to ensure the angle, horizontal and two main cutting edge bevel of equal length, about high. After grinding chisel edge, the bit during drilling cutting light, normal chip, does have a certain degree of difficulty. First, to help students build up confidence, confidence in the decision power. Master the methods and techniques in the future, sharpening a twist drill eligibility criteria and also difficult. Second, we must explicitly tell them to look less grinding, sharpening blind, the more wear the blind, to wear over a long drill, I do not know these. Less grinding see more analysis, more understanding, theory will slowly guide practice. Less grinding, is less wear when you do not receive, not grinding. This can save wasted blind sharpening to be concentrated on how to wear something. Look, is reading this knowledge, diagrams, see teachers grinding action, look good sharpening twist eligibility criteria, see all kinds of defects have sharpening twist. Meditation, the intention, this is very important. Twist to make them "good" and "bad" has a basic understanding. "Less grinding" First, "do not wear" That got bit hurried grind, grind must be blind. Sharpening good position before placing order for the next step, "sharpened" playing solid foundation, this step is very important. Teacher demonstration process, you can practice summed up the methods and techniques to explain and demonstrate the form of plain formulas, students often listen to understand, blow sister dressed leather wish guillotine J Po Wan stains barium acres gluttonous spasm of jealousy? To do the normal operation demonstration, step-action demonstrations, slow motion demonstration, so that the students easy to accept. Here the use of four formulas to guide the grinding process. Better. Formulas one: "settle tread edge against." This is the first step in the relative position of the drill bit and the wheel, often students are not on the cutting edge by grinding wheel began to settle on sharpening up. This is certainly not good grind. Here, "edge" is the main cutting edge, "settle" refers to part of the main cutting edge sharpening in a horizontal position. "Tread" means the wheel surface. "Fuck" is meant to slowly move closer. At this time the drill also can not touch the wheel. Two formulas: "drill shaft helical release front corner." This refers to the relationship between the position of the drill axis and the wheel surface. "Front corner" that angle 118 ° ± 2º half, about 60 ° in this position is very important, a direct impact on the size and angle drill main cutting edge shape and chisel edge bevel. To prompt the students to remember a common 30 °, 60 °, 90 ° in 60 ° angle triangle, the students easy to grasp. Formulas I and II are the formulas refers to the relative position of the front drill grinding, both to be balanced, do not settle gracefully angled edge while ignoring, or gracefully settle diagonal axis while ignoring the edge. In practice it will often these errors. Contact with the wheel is now ready to drill in the correct position under the circumstances. Three formulas: "from the edge toward the back ground behind." This refers to the entire flank from start slowly grinding bit edge. This facilitates cooling and grinding. Firmly entrenched formulas I, II, based on the drill bit gently touching the wheel this time, were relatively small amount of sharpening, to observe the uniformity of sparks when sharpening, the pressure is adjusted in a timely manner, and pay attention to the drill bit cool. When cooled resumed sharpening, to continue gracefully formulas I, II position, which is often difficult to grasp beginner, often involuntarily changes its position is correct. Four formulas:. "Bobbing tail not Alice" This action drill grinding process is also very important, when students tend to have sharpened the "bobbing" into a "turned up and down," another main cutting edges of the drill is destroyed. Gao Qiao at the same time can not drill the tail above the centerline of the wheel level, otherwise it would blunt the blade can not cut. Four sentences in the above formulas, based on the basic grasp of the essentials of the action, be timely to remind students to pay full attention after the drill angle, can not wear too large or too small. It can be a bit too much after the horn and the other branch is too small angle drill for students after the bench test drilling. Students will find, when too large angle drill after drill, was triangular or pentagonal orifice, severe vibration, the chip was needle; after crossing the small angle drill for drilling axial force is large, easy to cut, drill severe fever not drilling. Comparison, observation, repeated "less wear look" test drilling and grinding to the chisel appropriate, students can quickly master the correct twist drill grinding method, better control of the posterior horn size. When the test drill, drill chip light, no vibration, no expansion of the aperture, you can better drill grinding into other types of exercise.