Round tube flaring machinescan produce horn‑mouth(bell‑mouth)shapes when equipped with matching conical flaring mandrels,which is one of its standard tube‑end forming functions.It cannot form horn‑mouth only by adjusting parameters;dedicated dies are required.
Usable situations
1.Standard hydraulic round‑tube flaring machine:install conical horn‑mouth mandrel,can form 30°,45°,60°and other tapered bell‑mouth ends for carbon‑steel,galvanized round tubes.Widely used for pipe socket assembly,pre‑weld flaring for guardrail and handrail pipes.
2.For small‑diameter copper and aluminum tubes:dedicated flaring equipment can make high‑sealing‑performance horn‑mouth for refrigeration pipeline connections.
3.Automatic models maintain better batch uniformity;semi‑automatic versions are more dependent on manual centering.
Main limitations
1.Deformation ratio restriction
Single‑pass cold forming has safe expansion limit.Excessive flaring angle or too‑large diameter difference will cause tube‑end cracking,wall‑thickness thinning.Large‑opening horn‑mouth needs multi‑stage progressive flaring dies.
2.Wall‑thickness constraints
Ultra‑thin‑wall pipes:easy wrinkling and uneven horn‑mouth surface.
Over‑thick‑wall pipes:exceed machine tonnage,incomplete forming or die damage.
3.Material impact
Ordinary carbon‑steel galvanized pipes perform best.Galvanized layers may peel locally at flaring position,requiring anti‑rust treatment.High‑hardness alloy pipes accelerate die wear.
4.Shape limitation
Only for simple conical horn‑mouth.Complex curved‑surface bell shapes cannot be realized by ordinary ram‑type flaring machines;spinning‑type tube‑end forming equipment is needed instead.
Common defects
-Tube‑end cracking:excessive single‑pass deformation,sharp die corner.
-Oval horn‑mouth:misalignment between pipe and mandrel,unstable clamping.
-Uneven taper surface:worn mandrel or insufficient pressure holding time.
Practical tips
1.Select conical mandrel matching target horn‑mouth angle and final diameter.
2.Ensure pipe and mandrel are co‑axial,increase clamping stability.
3.For large‑angle horn‑mouth,adopt multi‑step flaring process instead of one‑shot forming.
4.Test‑form sample pieces first,inspect for cracks,ovality and taper before mass‑production.
Conclusion
The round tube flaring machine can process conventional conical horn‑mouth/bell‑mouth shapes with proper conical mandrels.It is not suitable for ultra‑large opening deformation and complex curved horn‑mouth profiles.Control expansion ratio and wall‑thickness scope to avoid cracking and wrinkling.
References
1.APA 7th
Wang,Q.(2024).Horn‑mouth forming process analysis of round tube flaring machine.
2.MLA 9th
Wang,Qiang."Horn‑Mouth Forming Process Analysis of Round Tube Flaring Machine.
3.GB/T 7714‑2015
WANG Q.Horn‑mouth forming process analysis of round tube flaring machine.
