Problems and solutions in the machining and measurement of reamer teeth

1. Machining and measuring methods and errors of reamer teeth

Generally, the teeth of the reamer are indexed and milled by the miller on the indexing head, and there are also small reamers that are grinded and indexed equally by grinding the cutter on the ring gear. That is to say, the miller is not on the center line of the reamer when setting the tool, and only changes the rake angle of the teeth without changing the uniformity of the division, which means that it has little effect on the measurement of the diameter of the two edges of the reamer. . But if the runout of the indexing head is installed with the reamer or the correction runout of the indexing head is incorrect or changed greatly, the milled teeth are not equally divided teeth, and the line between the two teeth does not pass through the axis of the reamer. In any case, it is measured The size of is not the diameter but the chord length.

Another situation is that when the tool is grinded on the rake face of the teeth, the grinding allowance is inconsistent, which affects the uniform distribution of the teeth and also causes measurement errors. If the cutter tooth is on the end face of the reamer, the problem will generally be found when visually inspecting the end surface; if the cutter tooth is in the middle of the reamer and blocked by the front guide, it is impossible to accurately visually detect the runout error of the milling indexing head. The influence of uneven error on the rake face of the cutting edge is greater. However, when the tool does not have a small relief angle of the cylindrical blade (the cylindricity of the cylindrical blade is generally between 0.8 and 1.2 mm), the true diameter of the reamer can be accurately measured, and it can be solved by paying attention.

2. Reamer measurement error solutions and ideas

(1) If there is a slight reduction in the size tolerance of the two blades measured by a micrometer compared with the dimension tolerance shown in the figure, it is not necessarily that the working diameter of the reamer is out of tolerance. Correct it first, and then measure and judge.

(2) When the measured size between the two blades is larger than the size tolerance indicated in the figure, it must be that the diameter of the reamer is larger and needs to be repaired, because any chord length will not be larger than the diameter.

(3) If the reamer has 4 blades or 6 blades, one pair of blades is within the qualified size range, and the other pairs of blades are too small in size, it does not necessarily mean that the reamer is unqualified. You must find the runout on the deflection instrument. If the runout of a few blades is qualified, the reamer must be a qualified product. If the runout is unqualified, it is possible that the teeth of the cutter are ground low, or the reamer is bent and deformed.

(4) Generally speaking, for the reamer within φ20mm, the error measured by the micrometer of the cutter teeth should be further speculated if the error is between 0~0.025mm, analyze the reasons, and do not easily judge that the reamer is unqualified.

(5) Milling cutter tooth opening and tool grinding tooth opening. The tool setting is not on the center of the workpiece, which will only affect the rake angle of the tooth, and will not affect the diameter measurement too much (for the corresponding equally divided tooth) .

(6) The eccentricity of the teeth of the small reamer has a great influence on the diameter measurement, so special attention should be paid to eliminate the cause to avoid misjudgment.

(7) Try it on the sample with the same material and heat treatment as the part, measure the reamed hole, compare the measurement result with the required size, and see if it is within the qualified range.