I. Basic Concepts of Internal and External Tube Chamfers

1.External chamfer: An inclined slope machined on the outer edge of a cut tube end. It primarily removes sharp external burrs to prevent scratching matching pipe fittings and sealing rings during assembly, and forms an external groove for welding.

2.Internal chamfer: An inclined slope machined on the inner edge of a tube end. It clears inward curled burrs inside the tube, avoids damage to internal rubber seals caused by burrs, prevents blockage of medium flow, and reduces eddy current resistance during fluid transportation.

3.General functions of both chamfers: Eliminate sharp edges, reduce stress concentration, and improve the performance of assembly, welding and sealing.

II. Processing Difficulties of Internal and External Tube Chamfers

1.Limited Operating Space for Internal Chamfering

The interior of the tube is enclosed with no direct visual access to the inner wall cutting process when the cutter extends into the tube. This often leads to incomplete burr removal and inconsistent chamfer depth, and post-inspection is difficult to implement.

2.Different Processing Defects Caused by Tube Wall Thickness

Thin-walled tubes are prone to extrusion deformation and out-of-round tube ends under clamping and cutting forces. Thick-walled tubes require larger cutting allowances, generating massive heat during continuous cutting. This results in rough machined surfaces and drastically accelerated tool wear.

3.Difficulties in Stable Control of Dimension and Coaxiality

Deviations in chamfer angle and uneven unilateral depth frequently occur during processing. Separate machining of internal and external chamfers easily causes misalignment with obvious steps at the tube end, which severely impairs sealing and welding forming quality.

4.Distinct Machining Characteristics of Various Materials

Stainless steel suffers severe work hardening during cutting, leading to rapid tool abrasion. Ductile soft materials such as aluminum and copper tend to have chips adhering to the tool tip, producing filamentary burrs. Plastic tubes are heat-sensitive; cutting heat melts the tube wall and causes adhesion to cutters.

5.Insufficient Rigidity of Internal Hole Cutters, Poor Machining Stability

Cutters for internal chamfering feature slender shanks constrained by tube inner diameter. Vibration easily arises during cutting and leaves chatter marks; in severe cases, tool tip chipping occurs. Simultaneous internal and external chamfering also carries risks of cutter interference.

6.High Difficulty in Consistency Control for Mass Production

Tubes inherently have minor dimensional defects such as slight ovality and bending, making full alignment during clamping and positioning hard to achieve. Equipment commissioning is complicated when switching tubes of different diameters and wall thicknesses, and manual machining cannot guarantee uniform chamfer specifications across all workpieces.