Common problems and solutions of tools in deep hole machining

In the process of deep hole machining, problems such as dimensional accuracy, surface quality and tool life of the workpiece often occur. How to reduce or even avoid these problems is an urgent problem to be solved. aluminum part
1. There are problems: the aperture increases, and the error is large
1) Cause
The design value of the outer diameter of the reamer is too large or the reaming cutting edge has burrs; the cutting speed is too high; the feed rate is improper or the machining allowance is too large; the reamer leading angle is too large; the reamer is bent; Adhering to the chip edge; the swing of the reaming cutting edge is out of tolerance during sharpening; the selection of cutting fluid is inappropriate; the oil stain on the surface of the taper shank is not wiped clean or the taper surface is damaged when the reamer is installed; the flat tail of the taper shank is installed in an offset position The rear taper shank of the machine tool spindle interferes with the cone; the spindle is bent or the spindle bearing is too loose or damaged; the reamer is inflexible; it is not on the same axis as the workpiece and the force of both hands is uneven when reaming by hand, causing the reamer to shake left and right.

2) Solutions
Appropriately reduce the outer diameter of the reamer according to the specific situation; reduce the cutting speed; appropriately adjust the feed rate or reduce the machining allowance; appropriately reduce the entering angle; straighten or scrap the bent unusable reamer; Qualified; control the swing difference within the allowable range; choose a cutting fluid with better cooling performance; before installing the reamer, the reamer taper shank and the internal oil stains of the machine tool spindle taper hole must be wiped clean, and the taper surface is polished with oil stone; Grind the flat tail of the reamer; adjust or replace the spindle bearing; re-adjust the floating chuck and adjust the coaxiality; pay attention to correct operation.
2. There is a problem: the aperture shrinks
1) Cause
The design value of the outer diameter of the reamer is too small; the cutting speed is too low; the feed rate is too large; the main declination angle of the reamer is too small; Shrinkage; when reaming steel parts, if the allowance is too large or the reamer is not sharp, it is easy to produce elastic recovery, so that the aperture is reduced and the inner hole is not round, and the aperture is unqualified. CNC machining steel part
2) Solutions
Replace the outer diameter of the reamer; appropriately increase the cutting speed; appropriately reduce the feed rate; appropriately increase the main declination angle; select an oily cutting fluid with good lubricating performance; When selecting the size of the knife, the above factors should be considered, or the value should be selected according to the actual situation; for experimental cutting, take the appropriate allowance and sharpen the reamer.
3. There is a problem: the reamed inner hole is not round
1) Cause
The reamer is too long, the rigidity is insufficient, and vibration occurs during reaming; the main declination angle of the reamer is too small; the reaming cutting edge is narrow; the reaming allowance is biased; the inner hole surface has gaps and cross holes; The spindle bearing is loose, there is no guide sleeve, or the clearance between the reamer and the guide sleeve is too large, and the workpiece is deformed after being removed due to the thin-walled workpiece being clamped too tightly.
2) Solutions
The reamer with insufficient rigidity can use the reamer with unequal pitch, and the installation of the reamer should adopt rigid connection to increase the leading angle; select the qualified reamer to control the hole position tolerance in the pre-processing process; adopt the unequal pitch For the reamer, use a longer and more precise guide sleeve; select qualified blanks; when using an equal-pitch reamer to ream more precise holes, the clearance of the machine tool spindle should be adjusted, and the matching clearance of the guide sleeve should be higher or appropriate. the clamping method to reduce the clamping force. cnc machining part
4. There is a problem: the inner surface of the hole has obvious facets
‍1) Cause
The reaming allowance is too large; the rear angle of the cutting part of the reamer is too large; the reaming cutting edge is too wide; the surface of the workpiece has pores, sand holes and the spindle swing is too large.
2) Solutions
Reduce the reaming allowance; reduce the clearance angle of the cutting part; sharpen the width of the margin; select the qualified blank; adjust the machine tool spindle.
5. There is a problem: the surface roughness value of the inner hole is high
1) Cause
The cutting speed is too high; the selection of cutting fluid is not appropriate; the main declination angle of the reamer is too large, and the reaming cutting edges are not on the same circumference; the reaming allowance is too large; the reaming allowance is uneven or too small, and the local surface is not reamed ;The swing of the cutting part of the reamer is out of tolerance, the cutting edge is not sharp, and the surface is rough; the cutting edge of the reamer is too wide; the chip removal is not smooth during reaming; the reamer is excessively worn; Edge; edge has built-up edge; due to material, not suitable for zero or negative rake angle reamers.
2) Solutions
Reduce the cutting speed; select cutting fluid according to the processing material; appropriately reduce the main declination angle, correctly sharpen the reaming cutting edge; appropriately reduce the reaming allowance; improve the position accuracy and quality of the bottom hole before reaming or increase the reaming allowance ; Select qualified reamer; sharpen the width of the blade; reduce the number of reamer teeth according to the specific situation, increase the space of the chip groove or use a reamer with an inclination angle to make the chip removal smooth; replace the reamer regularly, and grind it when sharpening. The cutting area is ground off; the reamer should take protective measures to avoid bumps during sharpening, use and transportation; for the bumped reamer, use extra-fine whetstone to repair the bumped reamer, or replace the reamer Knife; Trim with whetstone to pass, and use a reamer with a rake angle of 5°-10°.
6. There is a problem: the service life of the reamer is low
1) Cause
The material of the reamer is not suitable; the reamer is burnt during sharpening; the selection of cutting fluid is not suitable, the cutting fluid cannot flow smoothly, and the surface roughness value of the cutting part and after grinding of the reaming cutting is too high.
2) Solutions
Select the reamer material according to the processing material, and can use a cemented carbide reamer or a coated reamer; strictly control the amount of sharpening and cutting to avoid burns; often choose the correct cutting fluid according to the processing material; Pressure cutting fluid, after fine grinding or grinding to meet the requirements.
7‍. There is a problem: the position accuracy of the reamed hole is out of tolerance
1) Cause
The guide sleeve is worn; the bottom end of the guide sleeve is too far from the workpiece; the length of the guide sleeve is short, the accuracy is poor, and the spindle bearing is loose.
2) Solutions
Regularly replace the guide sleeve; lengthen the guide sleeve to improve the matching accuracy of the guide sleeve and the reamer clearance; timely repair the machine tool and adjust the spindle bearing clearance.
8. There is a problem: the reamer teeth are chipped
1) Cause
The reaming allowance is too large; the hardness of the workpiece material is too high; the swing of the cutting edge is too large, and the cutting load is uneven; the main angle of the reamer is too small, which increases the cutting width; when reaming deep holes or blind holes, there are too many chips , and it has not been removed in time and the teeth have been cracked during sharpening.
2) Solutions
Modify the pre-machined aperture size; reduce the hardness of the material or use a negative rake angle reamer or a carbide reamer; control the swing within the qualified range; increase the entering angle; pay attention to timely removal of chips or use a reamer with an inclination angle ; Pay attention to the sharpening quality.
9. There is a problem: the reamer handle is broken
1) Cause
The reaming allowance is too large; when reaming taper holes, the allocation of rough and fine reaming allowances and the selection of cutting amount are not appropriate; the chip space of the reamer teeth is small, and the chips are blocked.
2) Solutions
Modify the pre-machined aperture size; modify the allowance distribution, and select the cutting amount reasonably; reduce the number of reamer teeth, increase the chip space or grind the tooth gap by one tooth.
‍10. There is a problem: the center line of the hole after reaming is not straight
1) Cause
The drilling deflection before reaming, especially when the hole diameter is small, the original curvature cannot be corrected due to the poor rigidity of the reamer; the main declination angle of the reamer is too large; poor guidance makes the reamer easy to deviate during reaming direction; the reverse taper of the cutting part is too large; the reamer is displaced at the gap in the middle of the interrupted hole; when reaming by hand, the force is too large in one direction, forcing the reamer to deflect to one end and destroying the verticality of the reamed hole.
2) Solutions
Increase the reaming or boring process to correct the hole; reduce the main declination angle; adjust the appropriate reamer; replace the reamer with the guide part or lengthen the cutting part; pay attention to correct operation.