1、 Boring requirements
1. Before boring, carefully check whether the tooling, the positioning benchmark of the workpiece and each positioning element are stable and reliable.
2. Before boring, check whether the repeated positioning accuracy and dynamic balance accuracy of the equipment (spindle) meet the requirements of process processing and manufacturing.
3. During the trial boring of horizontal boring, the dynamic runout value of the gravity overhang of the boring bar must be checked, and the cutting parameters should be reasonably corrected to reduce the influence of centrifugal shear vibration.
4. Reasonably allocate the layer boring allowance according to the rough boring, semi fine boring and fine boring steps, and the rough boring allowance is about 0.5mm; The allowance of semi fine boring and fine boring is about 0.15mm, so as to avoid the phenomenon of tool letting caused by excessive allowance in semi fine boring, which affects the adjustment accuracy of fine boring allowance.
5. For difficult to machine materials and high-precision boring (tolerance ≤ 0.02mm), fine boring steps can be added, and the boring allowance is not less than 0.05mm to avoid elastic tool yield on the machining surface.
6. In the process of boring tool setting, attention must be paid to avoid the impact between the working part of the boring tool (blade and tool base) and the tool setting block, which will damage the blade and the guide groove of the tool base, so that the adjustment value of the boring tool will change and affect the machining accuracy of the aperture.
7. In the process of boring, pay attention to maintain sufficient cooling, increase the lubrication effect of the machined parts, and reduce the cutting force.
8. Strictly remove chips in each processing step to prevent chips from participating in secondary cutting and affecting the machining accuracy and surface quality of aperture.
Check the wear degree of the cutting tool (blade) at any time during the boring process, and replace it in time to ensure the machining quality of the aperture; It is forbidden to replace the blade in the fine boring step to prevent error 12 After each step of processing, the process quality control requirements must be strictly implemented, and the actual processing aperture must be carefully detected and recorded, so as to facilitate the analysis, adjustment and improvement of boring processing.
2、 Tool wear
In boring, the continuous cutting of tools is prone to wear and damage, which reduces the dimensional accuracy of hole machining and increases the surface roughness value; If you want to learn NC programming, you can help you in group 304214709. At the same time, the calibration of fine-tuning feed unit is abnormal, which leads to adjustment error, deviation of machining aperture and even product quality failure.
3、 Blade edge wear changes
1. Machining error
The machining error of boring is reflected in the changes of size, shape and position and surface quality after hole machining. The main influencing factors are:
(1) The length diameter ratio of the cutter bar is too large or the overhang is too long
(2) The blade material does not match the workpiece material
(3) Unreasonable boring amount
(4) Unreasonable allocation of allowance adjustment
(5) The offset of the initial hole position leads to the periodic change of the allowance
(6) The workpiece material is high rigidity or low plasticity, and the cutting tool or material shows the trend of cutting
2. Surface quality
(1) Boring fish scale shaped or threaded cuts on machined surfaces is a common surface quality phenomenon:
(2) Caused by the mismatch between the feed and speed of the tool
(3) Caused by rigid vibration of boring and tool wear
3. Adjustment error
In the boring process, because the operator needs to adjust the cutting amount of the distribution layer, it is easy to cause the machining dimensional accuracy deviation due to improper operation in the process of adjusting the distribution feed allowance.
4. Measurement error
Improper use of measuring tools and wrong measurement methods during and after boring are common quality hidden dangers in boring.