Manufacturing Processes and Procedures, Mechanical Manufacturing Technologies

Manual grinding twist drill inspection method

Source of the problem. CNC precision machining

The quality and efficiency of drill hole expansion depends to a large extent on the sharpness of the drill bit. The manual sharpening of the twist drill is based on the two-handed operation of the two eyes. For example, the two main cutting edges are the two-edge rotating grinding method, which edge is more (shorter) and more points are ground until the two eyes do not see the error. Then according to the method of reference teaching, the drill is erected in front of the eyes, two blades are one after the other, two eyes (usually monocular) look flat, which edge is high and which edge is short. Since the drilling edge produces parallax one after the other, it is necessary to use comparative methods to compare multiple 180° rotations. To find out which edge is high (short), we can grind this edge, or regrind it as described above ( To ensure symmetry, check again as above. Until after careful inspection, basically do not see the error (other aspects, after the corner, the top angle is also acceptable), the two major cutting edge grinding is completed, then continue to grind behind the steps or get back to use. CNC precision machining

2. Specific measures

Here we introduce a method for checking the lengths of two major cutting edges. This method is different from the previous method. That is to find a comparison method for reference objects (different from the previous model comparison method, because the model has many limitations and deficiencies). This reference is the straight edge of the bright aluminum door or window or the clear edge of the front building.

Specific methods: two eyes (or monocular) front view, look at the drill bit erected in front of the eyes, the two main cutting edges of the drill bit symmetrically, forward to find the front side of the reference material bright side (reference light top as far as possible with the line of sight), the drill (The two intersection points where the two main cutting edges intersect with the two edge cutting edges are outer points.) The outer edges are aligned with the reference line in front (coincidence), ie, the eye, outer tip, and reference line form a three-point line, as shown in the drawing. CNC precision machining

Three points and one line

Then turn the drill bit 180° according to the original axis line to see if the two outer tips of the bit are still coincident with the reference straight line, and then determine the height of the two edges. After turning the original axis to 180°, the two outer tips are always referenced to the front. If the straight line coincides, then the two main cutting edges of the drill must be equal symmetrically (provided that the two main cutting edges are centered around the same axis, in the same position, they are alternately grinded after rotating 180°, that is, the half angle is equal). After we use this method to judge, the probability of ultimate success is much higher than the traditional method. This method has also won the unanimous approval of many lathes and fitters. At the same time, we conducted an experiment and the experiment process was as follows: CNC precision machining

(1) Preparation. Prepare a few φ10mm old drills, grind only the two main cutting edges, do not repair the chisel edge, use them in the φ7mm bottom hole on the basis of the hole expansion, expand the hole with φ10H8 plug gauge to plug, found that not Go to find one of the drills as a model, and then use this drill to drill holes. The requirement is that the hole drilled meets φ10 (+0.133, +0.1) mm (a grinding plug gauge, one head is φ10.1mm, another One head is φ10.133mm). The drill has passed the sharpening and drilling tests several times before it meets the requirements. At the same time with both eyes observation and drilling test, which edge height (short) is found and marked, that is, the drill bit After wear, the outer diameter is ≤ φ10mm, and the drill tip is ≥ 0.05mm away from the center. CNC precision machining

(2) Test process and results. In the teaching process, 13 students were randomly selected to conduct tests (without knowing the new method). The 13 students were asked which edge height of the drill bit and which edge was short. As a result, 5 persons were incorrect and 8 persons were correct. After teaching the new method, continue to distinguish. Let them look through the window and use the top edge of the same high-rise building as a reference, and then the 13 people adopt new methods to judge. As a result, 2 people are wrong and 11 people are correct. Although the above old method has been practiced for a week, the probability of success of the students is only 61.5%. With the new method, students are taught on the spot and the probability of success of the students is as high as 84.6%. CNC precision machining

3. Conclusion

It can be judged which of the two major cutting edges of the drill bit is high and which is short, which is a step closer to the goal of grinding the drill bit with two equal major cutting edges. It is easy to ensure the work quality and improve the working efficiency by grinding the drill bit with two equal height main cutting edges. CNC precision machining

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china cnc machining parts manufacturer

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