Ten common problems in deep hole processing and their solutions
In the process of deep hole machining, there are always some problems such as dimension precision, surface quality and tool life. How to reduce or avoid these problems is a problem that we need to solve urgently.
1. The bigger the aperture, the bigger the error
1) cause
The design value of external diameter of reamer is too large or the reamer cutting edge has burr; the cutting speed is too high; the feed or machining allowance is too large; the main deflection angle of Reamer is too large; the Reamer is bent; the reamer cutting edge is adhered with chip; When the reamer is installed, the surface of the taper shank is not clean with oil or the taper face is bruised, the taper shank's flat tail offset is installed into the spindle of the machine tool and the taper shank conic interference; Spindle bending or spindle bearing too loose or damaged; Reamer floating is not flexible; with the workpiece and different Axis and hand reaming hole force uneven, so that reamer shaking left and right.
2) solutions
Reduce the outside diameter of Reamer, reduce the cutting speed, adjust the feed or reduce the machining allowance, reduce the main deflection angle, straighten or discard the bent reamer which can not be used Before installing reamer, it is necessary to clean the oil in the reamer taper Shank and the taper hole of the machine tool spindle, and repair the flat end of the reamer Adjust or replace the spindle bearing; re-adjust the floating Chuck, and adjust the coaxiality; pay attention to the correct operation.
2. Aperture reduction
1) cause
The design value of the external diameter of Reamer is too small; the cutting speed is too low; the feed is too large; the main deflection angle of Reamer is too small; the selection of cutting fluid is not suitable; the worn part of Reamer is not ground when the reamer is sharpened, and the elastic recovery reduces the aperture; when the Reamer is reamed, surplus is too large or not sharp reamer, easy to produce elastic recovery, reducing the aperture and the hole is not round, the aperture is not qualified.
2) solutions
Change the outside diameter of Reamer, increase the cutting speed, decrease the feed, increase the main deflection angle, choose the oil cutting fluid with good lubricity, exchange reamer regularly, correct edge grinding reamer cutting part, design reamer size, the above factors should be taken into account, or according to the actual situation; for experimental cutting, take appropriate allowance, will reamer sharpening.
3. The hole is not round
1) cause
The main deflection angle of the Reamer is too small; the cutting edge of the reamer is narrow; the tolerance of the reaming hole is too narrow; there are notches and cross holes on the surface of the inner hole; there are sand holes and air holes on the surface of the hole; the main shaft bearing is loose and there is no guide sleeve, or reamer and guide sleeve fit clearance is too large and because of thin-walled workpiece clamping too tight, after the workpiece deformation.
2) solutions
Reamers with insufficient rigidity can be reamers with unequal pitch, reamers should be installed with rigid connection to increase the main deflection angle, qualified reamers should be selected to control the hole position tolerance in the pre-machining process, and unequal pitch reamers should be used, using longer and more precise guide sleeve, selecting qualified blank, reaming more precise hole with equal-pitch reamer, the clearance of machine tool spindle should be adjusted, the clearance of guide sleeve should be higher or suitable clamping method should be adopted, reduce clamping force.
4. The inner surface of the hole has distinct edges
1) cause
Reaming hole allowance is too large; reamer cutting part back angle is too large; reaming cutting edge is too wide; workpiece surface has air hole, sand hole and spindle swing is too large.
2) solutions
Reduce the tolerance of reaming hole; reduce the back angle of cutting part; adjust the width of grinding edge band; select qualified blank; adjust the spindle of machine tool.
5. High Surface roughness
1) cause
The cutting speed is too high, the cutting fluid is not suitable, the main deflection angle of reamer is too large, the reaming cutting edge is not on the same circumference, the reaming hole allowance is too large, the reaming hole allowance is not uniform or too small, the local surface is not reamed; Reamer cutting part pendulum error, cutting edge is not sharp, rough surface; reamer cutting edge with too wide; reamer excessive wear; reamer impact, the edge with Burr or collapse; edge with debris; due to material, not Suitable for zero rake angle or negative rake angle reamers.
2) solutions
Cutting speed is reduced, cutting fluid is selected according to processing material, main deflection angle is reduced properly, cutting edge is ground correctly, reaming allowance is reduced properly, position accuracy and quality of bottom hole before reaming are improved or reaming allowance is increased, qualified reamer is selected To reduce the number of reamers, increase the space of the chip-holding groove or adopt reamers with edge obliquity to smooth chip removal; to replace reamers regularly, and to remove the grinding area when grinding; to remove the grinding area of reamers during grinding, using and transportation, protective measures should be taken to avoid the impact; for the reamers that have been damaged, repair the damaged reamers or replace the reamers with extra fine oilstone; for the reamers that have been reamers that have been damaged, use the reamers with 5 & DEG;-10 & DEG; Rake Angle.
6, reamer service life is low
1) cause
The reamer material is not suitable; the Reamer Burns during grinding; the cutting fluid is not properly selected, the cutting fluid does not flow smoothly, and the value of the Surface roughness at the cutting point and after reaming the reamer is too high.
2) solutions
Choose reamer material according to processing material, can use hard alloy reamer or coating reamer; strictly control cutting quantity of edge grinding to avoid burn; often choose cutting fluid correctly according to processing material; often remove chip in chip slot, with sufficient pressure of cutting fluid, after fine grinding or grinding to meet the requirements.
7. The position accuracy of the reaming 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 precision is poor and the spindle bearing is loose.
2) solutions
Replace the guide sleeve regularly, lengthen the guide sleeve, improve the matching precision between the guide sleeve and the reamer clearance, maintain the machine tool in time, adjust the spindle bearing clearance.
8. REAMER tooth collapse
1) cause
Reaming hole allowance is too large, workpiece material hardness is too high, cutting edge pendulum difference is too large, cutting load is not uniform; Reamer Main deflection angle is too small, so that the cutting width increases; reaming deep hole or blind hole, too many chips, and not in time to clear and grinding teeth have been grinding crack.
2) solutions
Modify the size of pre-machined Hole; reduce the hardness of material or use a negative rake reamer or carbide reamer; control the swing within the qualified range; increase the main deflection angle; pay attention to the timely removal of chips or use reamer with edge inclination angle; pay attention to the quality of grinding.
9. Reamer handle broken
1) cause
When reaming taper hole, the distribution of Coarse and fine reaming allowance and the selection of cutting parameters are not suitable, the space of chip holding of reamer teeth is small and the chip is blocked.
2) solutions
Modify the size of pre-machining Hole, modify the allowance distribution, reasonable selection of cutting parameters, reduce the number of reamer teeth, increase the capacity space or tooth clearance grinding a tooth.
10. The center line of the hole behind the reaming is not straight
1) cause
The deviation of the hole before reaming, especially when the hole diameter is small, can not correct the original bending degree because of the poor rigidity of the Reamer, the main deflection angle of the reamer is too large, the direction of the reamer is not good, so the reamer is easy to deviate from the direction in reaming, and the reverse cone of the cutting part is too large The reamer is displaced at the gap in the middle of the discontinuous hole, and the hand reamer is forced to tilt in one direction, which destroys the verticality of the hole.
2) solutions
Add reaming or boring process to correct hole; reduce main deflection angle; adjust suitable reamer; replace reamer with guide part or lengthen cutting part; pay attention to correct operation.
