In the process of deep hole drilling, problems such as dimension accuracy, surface quality and tool life often occur. How to reduce or even avoid these problems is an urgent problem to be solved. The following is a summary of 10 common problems and solutions in deep hole drilling.
1. The larger the aperture, the greater the error.
(1) Causes
The design value of reamer outer diameter is too large or the cutting edge of reamer has burrs; cutting speed is too high; feed quantity is inappropriate or machining allowance is too large; the main deflection angle of reamer is too large; the reamer is bent; chips are adhered to the reamer edge; the sway difference of reamer edge is too bad during grinding; the choice of cutting fluid is inappropriate; the surface oil of taper shank when reamer is installed The contamination is not clean or the conical surface is bumped; the flat tail of the conical shank is offset and loaded into the spindle of the machine tool, and the conical shank interferes; the spindle is bent or the bearing of the spindle is too loose or damaged; the reamer is not flexible; the force of both hands is uneven when the reamer is different from the workpiece and the reamer hole, which makes the reamer sway left and right.
(2) Solutions
Reduce the reamer's outer diameter appropriately according to the specific conditions; reduce the cutting speed; adjust the feed or reduce the processing allowance appropriately; reduce the main deflection angle appropriately; straighten or scrap the unusable reamer that bends; carefully trim it to qualified with oil stone; control the swing error within the allowable range; select the cutting fluid with better cooling performance; install the reamer. Before the cutter, the oil stain inside the reamer taper shank and the taper hole of the machine tool spindle must be wiped off, and the conical surface should be polished with asphalt; the flat tail of the reamer should be polished; the spindle bearing should be adjusted or replaced; the floating chuck should be adjusted and the coaxiality should be adjusted; and the correct operation should be paid attention to.
2. Aperture reduction
(1) Causes
The design value of reamer outer diameter size is small; cutting speed is too low; feed is too large; reamer main deviation angle is too small; cutting fluid selection is not appropriate; the wear part of reamer is not worn off during grinding, and the elastic recovery reduces the aperture; when reaming steel parts, the surplus 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, aperture unqualified.
(2) Solutions
Replacement of reamer outer diameter size; appropriate increase of cutting speed; appropriate reduction of feed; appropriate increase of main deviation angle; selection of lubricating oil cutting fluid; regular exchange of reamers, correct grinding of reamer cutting parts; design reamer size, should consider the above factors, or take values according to actual conditions; experimental cutting, Take the appropriate allowance and sharpen the reamer.
3. The hinged inner hole is not round.
(1) Causes
The reamer is too long, rigid enough and vibrates when reaming; the main deviation angle of the reamer is too small; the cutting edge of the reamer is narrow; the reamer allowance is too large; the surface of the inner hole has notches and intersecting holes; the surface of the hole has sand holes and air holes; the bearing of the main shaft is loose, there is no guide sleeve, or the clearance between the reamer and the guide sleeve is too large, and the clamping of the thin-walled workpiece is too tight. Workpiece deformation after unloading.
(2) Solutions
The reamers with insufficient rigidity can adopt reamers with unequal tooth spacing, and the installation of reamers should adopt rigid connection to increase the main deviation angle; select qualified reamers to control the hole position tolerance in the pre-processing process; adopt unequal tooth spacing reamers with longer and more precise guide sleeves; select qualified blanks; adopt reamers with equal tooth spacing to ream more precisely. When the holes are dense, the clearance of the machine tool spindle should be adjusted, and the matching clearance of the guide sleeve should be higher or appropriate clamping method should be adopted to reduce the clamping force.
4. There are obvious edges on the inner surface of the hole.
(1) Causes
Excessive reaming allowance, too large reamer cutting back angle, too wide reaming edge band, too large air hole, sand hole and spindle swing difference on workpiece surface.
(2) Solutions
Reduce reaming allowance; reduce the back angle of cutting part; grinding edge width; select qualified blanks; adjust machine tool spindle.
5. High Surface Roughness of Inner Hole
(1) Causes
Excessive cutting speed; inappropriate choice of cutting fluid; too large main deviation angle of reamer, reaming edge not on the same circumference; too large reaming allowance; uneven or too small reaming allowance, local surface not reamed; excessive swing difference of reamer cutting part, not sharp edge, rough surface; too wide reaming edge; no chip removal when reaming hole Excessive wear and tear of reamer; reamer bruises with burrs or breaking edges; edges with debris tumors; due to material relations, it is not suitable for reamers with zero or negative rake angles.
(2) Solutions
Reduce cutting speed; Choose cutting fluid according to the processing material; Reduce the main deviation angle properly, grind the cutting edge correctly; Reduce the reaming allowance properly; Improve the accuracy and quality of reaming front and bottom hole or increase reaming allowance; Choose qualified reamer; Grind blade width; Reduce the number of reamer teeth according to the specific situation, increase the capacity chip. Groove space or the use of reamers with inclined edges to smooth chip removal; regular replacement of reamers to grind the grinding area when grinding; reamers in the grinding, use and transportation process, should take protective measures to avoid bruising; for the damaged reamers, the use of extra-fine tar stones to repair the bruised reamers, or replace reamers; repair with tar stones; The reamer with front angle of 5 -10 is used to qualify.
6. Low service life of reamers
(1) Causes
Reamer material is not suitable; reamer burns in grinding; cutting fluid selection is not appropriate, cutting fluid can not flow smoothly, cutting location and surface roughness after reamer grinding are too high.
(2) Solutions
Carbide reamer or coated reamer can be used to select reamer materials according to processing materials; cutting parameters should be strictly controlled to avoid burns; cutting fluids should be selected correctly according to processing materials; chips in chip grooves should be removed regularly, and cutting fluids with sufficient pressure should be used to finish grinding or grinding.
7. Excess accuracy of hinged hole position
(1) Causes
Wear of guide sleeve; too far from the workpiece at the bottom of guide sleeve; short length of guide sleeve, poor accuracy and loosening of spindle bearing.
(2) Solutions
Regular replacement of guide sleeve; lengthening guide sleeve to improve the matching accuracy between guide sleeve and reamer clearance; timely maintenance of machine tools, adjustment of spindle bearing clearance.
8. Reamer teeth cracking
(1) Causes
Reaming hole allowance is too large; workpiece material hardness is too high; cutting edge swing difference is too large, cutting load is not uniform; reamer main deviation angle is too small, so that cutting width increases; reaming deep hole or blind hole, too much chips, and not timely clearance and grinding tool teeth have been grinded.
(2) Solutions
Modify the pre-processed aperture size; reduce material hardness or change to negative front angle reamer or carbide reamer; control the swing difference within the eligible range; increase the main deflection angle; pay attention to timely removal of chips or the use of inclined edge reamer; pay attention to grinding quality.
9. Hinge handle broken
(1) Causes
Excessive reaming allowance, inappropriate distribution of rough and fine reaming allowance and selection of cutting parameters when reaming taper hole, small chip space of reamer teeth and chip blockage.
(2) Solutions
Modify the pre-machined aperture size, modify the allowance allocation, select the cutting parameters reasonably, reduce the number of reamer teeth, increase the chip space or grind the clearance of the cutter teeth.
10. The center line of reaming rear hole is not straight
(1) Causes
Drilling hole deviation before reaming, especially when the aperture is small, can not correct the original bending because of the poor rigidity of reamer; the main deviation angle of reamer is too large; the poor guidance makes reamer easily deviate from the direction in reaming; the chamfer of cutting part is too large; the reamer displaces at the gap in the middle of the discontinuous hole; the reamer is used in one direction when reaming a hand hole. Too much force forces the reamer to deflect to one end, which destroys the verticality of the reamer.
(2) Solutions
Increase the reaming or boring process correction hole; reduce the main deviation angle; adjust the appropriate reamer; replace the reamer with the guide part or lengthen the cutting part; pay attention to the correct operation.