Common problems and solutions in deep hole machining

1. Aperture reduction

Reason: the design value of reamer outside diameter is small; Cutting speed is too low; Excessive supply; The main Angle of reamer is too small; Improper selection of cutting fluid; The worn part of the reamer is not worn off when grinding, and the elastic recovery reduces the aperture. When reaming steel parts, the allowance is too large or the reamer is not sharp, easy to produce elastic recovery, so that the hole diameter is reduced and the inner hole is not round, the hole diameter is not qualified.

Solution: change the outside diameter of the reamer; Increase the cutting speed appropriately; Appropriate reduction of feed; Increase the main declination Angle appropriately; Choose oil cutting fluid with good lubricating property; Regular exchange of reamer, correct grinding reamer cutting parts; When designing the size of the reamer, the above factors should be considered, or the value should be determined according to the actual situation. For experimental cutting, take the appropriate allowance and sharpen the reamer.

2. Pore diameter increases

Causes: the reamer diameter is too large or the cutting edge of the reamer has burrs;Excessive cutting speed; Improper feeding or excessive processing allowance; Excessive main Angle of reamer bending; The cutting edge of the hinge adheres to the chip tumor;When grinding, the cutting edge of the hinge is out of tolerance. Improper selection of cutting fluid; When reamer is installed, the surface of taper handle is not cleaned or the taper surface is bruised; The flat tail offset of the taper shank is loaded into the conical interference of the taper shank behind the spindle of the machine tool; Spindle bending or spindle bearing too loose or damaged; Reamer float is not flexible; When not coaxial with the workpiece and hand reaming, both hands force is not uniform, so that the reamer shaking from side to side.

Solution: reduce the outer diameter of the reamer appropriately according to the specific situation; Reduce cutting speed adjust feed or reduce machining allowance; Properly reduce the main deflection Angle straightening or scrap bending reamer which can not be used; Carefully trim with whetstone to qualified; The control swing is within the allowable range;Select cutting fluid with better cooling performance; Before installing the reamer, the oil inside the taper shank of the reamer and the taper hole of the machine tool spindle must be wiped clean, and the taper surface with bumps must be polished with oil stone; Reamer flat tail adjustment or replacement of spindle bearing; Readjust floating chuck head and adjust coaxiality; Pay attention to correct operation.

3. The inner hole hinged out is not round

Causes: excessive length of reamer, insufficient rigidity, vibration during reaming; The main Angle of reamer is too small; Narrow cutting edge band;Reaming allowance deviation; The inner hole surface has gaps and cross holes; There are sand holes and air holes on the surface of holes. The spindle bearing is loose without guide sleeve, or the clearance between the reamer and guide sleeve is too large, and the workpiece is deformed after being removed due to too tight clamping of the thin-wall workpiece.

Solution: the lack of rigidity of the reamer can be used not equal pitch reamer, reamer installation should use rigid connection, increase the main deflection Angle; Select the qualified reamer, control the hole position tolerance of the preprocessing procedure;Adopt unequal pitch reamer, adopt longer and more precise guide sleeve; Select qualified blank; When using equal pitch reamer to ream more precise hole, the clearance of machine tool spindle should be adjusted, the fit clearance of guide sleeve should be higher or proper clamping method should be adopted to reduce the clamping force.

4. The accuracy of reamed holes is out of tolerance

Cause: guide sleeve wear; The bottom end of the guide sleeve is too far away from the workpiece; Short length of guide sleeve, poor accuracy and loose spindle bearing.

Solution: replace the guide sleeve regularly; Lengthening guide sleeve can improve the precision of fit between guide sleeve and reamer clearance. Timely maintenance of machine tools, adjust the spindle bearing clearance.

5. High surface roughness value of inner hole

Causes: cutting speed is too high; Improper selection of cutting fluid; The main Angle of the reamer is too large, and the cutting edge of the reamer is not on the same circumference. Excessive reaming allowance; Uneven or too small reaming allowance, local surface not reamed; The reamer cutting part is out of swing, the edge is not sharp, the surface is rough; Excessive width of cutting edge belt; Poor chip removal during reaming; Excessive wear of reamer; The reamer is bruised, and the cutting edge is left with burr or chipping edge; There are chip nodules on the edge; Due to material, it is not suitable for zero Angle or negative Angle reamer.

Solution: reduce the cutting speed; Select cutting fluid according to deep hole machining material; Properly reduce the main Angle, correct cutting edge grinding hinge;Reduce reaming allowance appropriately; Improve the position accuracy and quality of the bottom hole before reaming or increase the reaming allowance; Select qualified reamer;The width of the grinding blade belt; Reduce the number of teeth of the reamer according to the specific situation, increase the space of the chip holding groove or use the reamer with the edge Angle, so that the chip removal is smooth; Change the reamer regularly and grind the grinding area when grinding the edge; In the process of grinding, using and transporting the reamer, protective measures should be taken to avoid collision. For banged reamers, repair or replace the banged reamers with extra fine whetstone; With oil stone renovation to qualified, USES the anterior horn 5 ° to 10 ° of the reamer.

6. The inner surface of the hole has obvious edges

Causes: excessive reaming allowance; The rear Angle of the reamer cutting part is too large;Excessive width of cutting edge belt; The workpiece surface has blowhole, sand hole and the spindle pendulum is too big.

Solution: reduce reaming allowance; Reduce the back Angle of cutting part; The width of the grinding blade belt; Select qualified blank; Adjust the machine spindle.

7. The center line of the hole is not straight after reaming

Causes: the deviation of the borehole before reaming, especially when the hole diameter is small, cannot correct the original bending degree due to the poor rigidity of the reamer; The reamer main deflection Angle is too large; Poor guide makes the reamer easy to deviate from the direction in reaming;Cutting part inverted cone is too large; Displacement of the reamer at the clearance of the intermittent hole; When reaming by hand, excessive force in one direction forces the reamer to deflect towards one end, damaging the verticality of reaming.

Solution: add reaming or boring process correction hole; Decrease the main declination Angle; Adjust the appropriate reamer; Replace reamer with guide part or lengthened cutting part; Pay attention to correct operation.

8. Low service life of reamer

Causes: improper reamer materials; Burn the reamer while sharpening the blade; The cutting fluid selection is not suitable, the cutting fluid is not able to flow smoothly, the cutting place and the hinge cutting edge grinds the surface roughness value is too high.

Solution: according to the choice of reamer materials reamer materials, can use carbide reamer or coated reamer; Strictly control cutting parameters to avoid burn; Often choose cutting fluid correctly according to machining material; Often clear chip groove chip, with enough pressure cutting fluid, through fine grinding or grinding to meet the requirements.

9, reamer blade tooth collapse

Causes: excessive reaming allowance; The workpiece material hardness is too high; Excessive cutting edge swing leads to uneven cutting load. The main Angle of reamer is too small, which increases the cutting width. When reaming deep holes or blind holes, there are too many chips, which are not cleared in time, and the cutter teeth have been worn and cracked when grinding.

Solution: modify the hole size of pre-machining; Reduce the hardness of the material or change to negative front Angle reamer or carbide reamer; The control swing is within the qualified range; Increase the main declination Angle; Pay attention to remove the chip or use the Angle reamer with edge; Pay attention to the cutting edge grinding quality.

10. The handle of reaming tool is broken

Causes: excessive reaming allowance; When reaming taper holes, coarse and fine reaming allowance allocation and cutting parameters selection are not appropriate; Reamer tooth chip space is small, chip plug.

Solution: modify the hole size of pre-machining; Modify allowance allocation, reasonable choice of cutting parameters; Reduce the number of teeth in the reamer, increase the chip space or grind the clearance of the cutter teeth.