10 common problems in deep hole processing

In the process of deep hole processing, there are often problems such as the dimensional accuracy of the workpiece, surface quality and tool life, how to reduce or even avoid these problems, is our current problem to be solved, the following summarizes the 10 common problems and solutions in deep hole processing.

1

The aperture increases, the error is large

1) Cause

The design value of the outside diameter of the reamer is too large or the cutting edge of the reamer has burrs; Cutting speed is too high; Improper feed amount or excessive processing allowance; Reamer main deflection Angle is too large; The reamer bends; There are chip nodules sticking on the cutting edge of reamer. During grinding, the swing difference of the cutting edge is out of whack; Cutting fluid selection is not appropriate; When installing the reamer, the oil on the surface of the taper handle is not wiped clean or the cone surface is bruised; The flat tail of the taper shank is offset into the conical interference of the rear taper shank of the machine tool spindle; Spindle bent or spindle bearing too loose or damaged; Reamer floating is not flexible; It is not coaxial with the workpiece and the hand reaming force is not uniform, so that the reamer shakes around.

2) Solution

Reduce the outside diameter of the reamer appropriately according to the specific situation; Reduce cutting speed; Adjust the feed rate appropriately or reduce the processing allowance; Appropriately reduce the main declination Angle; Unserviceable reamer that has been straightened or scrapped for bending; Carefully trim with a whetstone; Control the swing difference within the allowable range; Select cutting fluid with good cooling performance; Before installing the reamer, the oil inside the reamer taper handle and the spindle taper hole of the machine tool must be wiped clean, and the bump on the cone surface should be polished with oil stone; Trim flat reamer tail; Adjust or replace the main shaft bearing; Readjust the floating card head and adjust the coaxiality; Pay attention to correct operation.

2

Aperture reduction

1) Cause

The design value of the outside diameter of the reamer is too small; Cutting speed is too low; Excessive feed; The main deflection Angle of reamer is too small; Cutting fluid selection is not appropriate; The wear part of the reamer is not worn off during sharpening, and the elastic recovery reduces the aperture. When reaming steel parts, the margin 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.

2) Solution

Change the outside diameter of the reamer; Appropriately increase the cutting speed; Appropriately reduce the feed rate; Appropriately increase the main declination Angle; Select oily cutting fluid with good lubrication performance; Regular exchange of reamer, correct sharpening of reamer cutting parts; When designing the reamer size, the above factors should be considered, or the value should be based on the actual situation; For experimental cutting, take the appropriate margin and sharpen the reamer.

3

The hinged inner hole is not round

1) Cause

The reamer is too long, the rigidity is not enough, and the vibration occurs during reamer. The main deflection Angle of reamer is too small; Hinge cutting edge belt narrow; Deviation of reaming allowance; The surface of the inner hole has notches and cross holes; There are sand holes and stomata on the surface of holes. The main shaft 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 unloading due to the tight clamping of the thin-walled workpiece.

2) Solution

The reamer with unequal pitch can be used for the reamer with insufficient rigidity, and the installation of the reamer should adopt rigid connection to increase the main deflection Angle; Select qualified reamer to control hole position tolerance in pre-machining process; The use of unequal pitch reamer, the use of longer, more precise guide sleeve; Selection of qualified blanks; When the same pitch reamer is used to reamer more precise holes, the spindle clearance of the machine tool should be adjusted, and the matching clearance of the guide sleeve should be required to be higher or appropriate clamping method should be adopted to reduce the clamping force.

4

The inner surface of the hole has a distinct edge

1) Cause

Excessive reaming allowance; The rear Angle of the cutting part of the reamer is too large; Hinge cutting edge belt is too wide; The surface of the workpiece has pores, sand holes and the spindle swing difference is too large.

2) Solution

Reduce reaming allowance; Reduce the back Angle of the cutting part; Grinding edge band width; Select qualified blank; Adjust the machine spindle.

5

The surface roughness of the inner hole is high

1) Cause

Cutting speed is too high; Cutting fluid selection is not appropriate; The main deflection Angle of the reamer is too large, and the cutting edge of the reamer is not in the same circle; Reaming margin is too large; The reaming allowance is uneven or too small, and the local surface is not reamed to; The swing of the cutting part of the reamer is abnormal, the cutting edge is not sharp, and the surface is rough; Hinge cutting edge belt is too wide; Chip discharge is not smooth when reaming; Excessive reamer wear; The reamer is injured, the cutting edge has burrs or broken edges; There are chip nodules at the cutting edge; Not suitable for zero or negative front Angle reamers due to material.

2) Solution

Reduce cutting speed; Select the cutting fluid according to the processing material; The main declination Angle should be reduced properly and the cutting edge should be sharpened correctly. Appropriately reduce the reaming allowance; Improve the position accuracy and quality of the bottom hole before reaming or increase the reaming margin; Selection of qualified reamer; Grinding edge band width; According to the specific situation, reduce the number of reamer teeth, increase the space of chip slot or adopt the reamer with the Angle of edge to make the chip removal smooth; Replace the reamer regularly and remove the grinding area when sharpening; During the sharpening, use and transportation of the reamer, protective measures should be taken to avoid injury; The damaged reamer should be repaired or replaced with extra fine oil stone. Trim with a whetstone and use a reamer with a front Angle of 5°-10°.

6

The service life of the reamer is low

1) Cause

Reamer material is not suitable; The reamer is burned during sharpening; The cutting fluid selection is not appropriate, the cutting fluid does not flow smoothly, and the surface roughness value of the cutting place and the surface roughness after grinding of the reaming cutting tool is too high.

2) Solution

The reamer material can be selected according to the processing material, carbide reamer or coated reamer can be used; Strictly control the cutting amount of grinding to avoid burns; The cutting fluid is often correctly selected according to the machining material; Often remove the chips in the chip tank, with enough pressure cutting fluid, through fine grinding or grinding to meet the requirements.

7

The precision of the reamed hole position is out of tolerance

1) Cause

Guide sleeve wear; The bottom end of the guide sleeve is too far from the workpiece; Short guide sleeve length, poor accuracy and loose main shaft bearing.

2) Solution

Replace guide sleeve regularly; Lengthening guide sleeve to improve the matching accuracy of guide sleeve and reamer clearance; Timely maintenance of machine tools, adjust spindle bearing clearance.

8

Reamer teeth cracked

1) Cause

Excessive reaming allowance; Workpiece material hardness is too high; The swing difference of cutting edge is too large, and the cutting load is not uniform; The main deflection Angle of the reamer is too small, which increases the cutting width. When reaming deep holes or blind holes, there are too many chips, which are not removed in time, and the teeth of the tool are worn and cracked during sharpening.

2) Solution

Modify the premachined aperture size; Reduce material hardness or switch to negative front Angle reamer or carbide reamer; Control the swing difference within the qualified range; Increase the main deflection Angle; Pay attention to remove chips in time or use Angle reamer with edge; Pay attention to sharpening quality.

9

Reamer handle is broken

1) Cause

Excessive reaming allowance; When reaming taper holes, the allocation of coarse and fine reaming allowance and the selection of cutting parameters are not appropriate. Reamer tooth chip space is small, chip blocking.

2) Solution

Modify the premachined aperture size; Modify the allowance allocation and select the cutting quantity reasonably; Reduce the number of reamer teeth, increase the chip space or sharpen the gap between cutter teeth to remove one tooth.

10

The center line of the reaming hole is not straight

1) Cause

The deflection of the hole before reaming, especially when the aperture is small, can not correct the original bending degree due to the poor rigidity of the reamer; Reamer main deflection Angle is too large; Poor guidance, so that the reamer is easy to deviate from the direction in the reamer; The cutting part of the taper is too large; The reamer displaces in the middle gap of the intermittent hole; When reaming by hand, excessive force in one direction forces the reamer to tilt towards one end, destroying the verticality of the reaming.

2) Solution

Add reaming or boring process correction holes; Reduce the main declination Angle; Adjust the appropriate reamer; Replace a reamer with a guide part or a lengthening cutting part; Pay attention to correct operation.