Neometrix / Metal Forming Machines / Tube Bending Machine / NMX-PBM-93

NMX-PBM-93 · ENGINEERED-TO-ORDER CLASS — PART · TOOLING · MACHINE · SAFETY · BUILD · PROVE

Tube Bending Machine. Hold the wall. Hit the angle.

Name: Tube Bending Machine
Brand: Neometrix
SKU: NMX-PBM-93

A tube bending machine turns a straight length of tube or pipe into a bent part to a drawing: it clamps the tube, swings it round a die, and feeds and turns it for the next bend. Neometrix engineers it as a system around the part: the choice of tooling, the hydraulic drive, the bend table, the guarding and the proof.

So the machine has to keep the wall round and even through every bend, reach the angle after the tube springs back, and repeat it, part after part.

Discuss a bending machine Capability note (PDF)

A tube bending machine on a plain white studio background: a long low pale grey steel bed on plain feet with a round grooved bend die and a clamp block at one end, a pressure die block on a short hydraulic cylinder with a bright chrome rod, a carriage on a rail holding a long bright stainless tube that is already bent in a smooth curve, a pale grey hydraulic power unit behind joined by two bright hoses, a plain blank control cabinet on an arm, a clear guard panel beside the bend head, and no people

Fig · 01 — A tube bending machine: a bed with a bend die and clamp, a pressure die on its cylinder, a carriage holding the tube, and a hydraulic power unit behind, with a tube already bent — illustrative render.

The result

a bent part that matches the drawinground, even in the wall, and at the angle

The tooling

clamp, bend die, pressure die, wiper and mandrelcut to the tube, not to the machine

The drive

hydraulic, from one power unitclamp, pressure die, bend and mandrel in turn

The control

a bend table, run bend by bendlength, rotation and angle for every bend

Status

engineered to orderno delivered bending machine claimed

ISO 9001ISO 14001ASME B31.3 reference for process pipingPFI ES-24 reference for pipe bending

Overview

What a bend does to the tube, and what the machine has to do about it.

Because a bend stretches one wall and squeezes the other, and a bending machine is judged by what it leaves in the part.

A set of bending tooling laid out on a plain white studio background: a thick round grooved bend die of bright steel standing on edge, a flat clamp die block, a pressure die block, a wiper die with a thin sharp edge, a long bright steel mandrel rod with five round ball segments linked on its end, and one short bright stainless tube bent into a smooth curve, and no people

Fig · 02 — The tooling that holds the wall: a bend die, a clamp die, a pressure die, a wiper die and a mandrel with ball segments, beside a bent tube — illustrative render.

Hold the wall. Hit the angle.

What the machine is for

It bends tube and pipe to a drawing. A clamp grips the tube, a bend die turns it, a carriage feeds it, and a rotation axis turns it between bends so that each bend lies in its own plane. It serves piping shops, boiler and heat-exchanger shops and maintenance workshops.

What a bend does to the tube

The outside of a bend is stretched, so its wall gets thinner. The inside is squeezed, so its wall can wrinkle. The round section tends to flatten into an oval. The tighter the bend, the more of each there is.

Why the wall has to be held

A tube bent with nothing inside it and nothing beside it will do all three. So the tooling holds it. A pressure die pushes the tube into the bend die. A wiper die supports the inside just behind the bend. A mandrel inside the tube keeps it round. A boost on the pressure die helps the tube through the bend and limits the thinning.

Why the tooling is cut to the tube

The clamp, the dies and the mandrel are cut to the outside diameter and the radius. A thin wall and a tight bend ask for the full set. A thick wall and an easy bend may need less. The tooling is chosen from the part, and not from the machine.

Why the tube springs back

When the bend arm lets go, the elastic part of the bend relaxes and the angle opens a little. So the machine has to bend further than the angle it wants. How much further depends on the material, the wall and the radius, so it is learned from trial bends and kept in the bend table.

Why a bend table drives the machine

Each bend is described by a length, a rotation and an angle. The machine runs them in order: feed to the length, turn to the plane, bend to the angle. The table is kept with the part number, so that the next batch starts where the last one ended.

Why a hydraulic drive

Hydraulics give a large, smooth and controllable force from a compact unit. One power unit can close the clamp, set the pressure die, drive the bend arm and move the mandrel, each in its own step, and hold each one where it is.

Why every first part is checked

The first part of a batch is checked against the drawing for angle, length and plane, and for the wall and the section at the bend. A machine that bends well and is never checked cannot say so.

The method

Part, tooling, machine, safety, build and prove.

Six steps in a fixed order. The tooling and the proof are the two that a quick job skips.

1 · Part

The tube and the drawing are noted: the material, the outside diameter and wall, the bend radius, the number of bends, the straight lengths between them, and what the part is for.

2 · Tooling

The clamp, bend, pressure and wiper dies and the mandrel are chosen for the tube and the radius, and the need for a mandrel is decided from the wall and the bend.

3 · Choose the machine

The size of machine, the drive and the axes are chosen to carry the part with force to spare, and the bed is made long enough for the longest straight.

4 · Make it safe

Guarding covers the swing of the bend arm and the carriage and stops the machine when it is opened. An emergency stop is fitted, and trapped hydraulic pressure can be released.

5 · Build

The bed, the bend head, the carriage, the power unit and the controls are built and fitted, with the hydraulics flushed and the axes aligned.

6 · Prove

Trial bends are run on the customer's own tube, the springback table is written, the first part is checked against the drawing, and the record is handed over with the machine.

Which defect, which cure

What you see	What causes it	What the machine does about it
Wrinkles on the inside of the bend	the inside wall is squeezed more than it can carry	a wiper die close behind the bend, and a mandrel inside the tube
A thin wall on the outside	the outside wall is stretched	a boost on the pressure die, and a radius the wall can bear
A flattened section	the round section collapses as it turns	a mandrel with ball segments fitted to the bore, and a lubricant
An angle that opens after release	the elastic part of the bend relaxes	an overbend taken from the springback table
Marks and scratches	the tube drags over a dry die	a lubricant, clean dies and a wiper die set true
A bend in the wrong plane	the rotation between bends is wrong	a rotation axis read from an encoder, and a bend table checked on the first part

The step people underrate is the trial bend. A springback table written from the customer's own tube is worth more than one taken from a book.

Work content

What the machine contains, element by element.

Read it as a checklist: a machine missing a row will bend tube, but it will not hold the wall or hit the angle.

A hydraulic pipe bending machine for larger pipe with its power unit on a plain white studio background: a heavy welded pale grey steel frame with a large grooved bend die and a swinging bend arm driven by a thick hydraulic cylinder with a bright chrome rod, a thick steel pipe lying across the frame and bent part way into a curve, a pale grey hydraulic power unit with a motor, a pump block, a reservoir and a small heat exchanger beside it joined by bright braided hoses, a plain blank control box, and no people

Fig · 03 — A hydraulic pipe bender with its power unit: a heavy frame, a bend die and a bend arm on a thick cylinder, a pipe part way through its bend, and the motor, pump and reservoir beside it — illustrative render.

Element	What it does	What matters
Bed and frame	carry the bend head	a rigid fabricated bed, long enough for the longest straight, with a rail for the carriage and a stiff mounting for the bend head
Bend head	bends the tube	a bend arm turning on its pivot with a clamp die and a bend die, driven by a hydraulic cylinder or motor, with an encoder on the arm
Pressure die and boost	push the tube into the bend	a pressure die on its own cylinder, with a boost that follows the tube through the bend and limits the thinning
Wiper die and mandrel	hold the wall	a wiper die set close behind the bend, and a mandrel on a rod with ball segments, drawn back after the bend
Carriage and rotation	feed and turn the tube	a carriage on a rail that holds the tube and feeds it, and a rotation axis that turns it between bends
Hydraulic power unit	supplies the drive	a motor and pump, a reservoir, filters, relief valves and valves for the clamp, the pressure die, the bend and the mandrel, with a heat exchanger where the duty needs one
Controller	runs the bend table	a controller that holds the length, rotation and angle of every bend, runs them in order, and keeps the springback correction with the part number
Measurement	checks the part	encoders on the bend arm, the carriage and the rotation, and a check of the first part against the drawing
Guarding and emergency stop	protect the operator	interlocked guards around the swing and the carriage, an emergency stop, and a way to release trapped pressure
Tooling set	forms the part	clamp, bend, pressure and wiper dies and mandrels cut to the tube and the radius, with a spare set for the next size
Lubrication	keeps the surface and eases the bend	a lubricant on the mandrel and the wiper die, applied the same way every time
Testing & documentation	prove the machine first	trial bends on the customer's own tube, the springback table, the guards and the stop exercised, and a record the customer can inspect

The elements that decide the result are the wiper die and mandrel and the bend table, and the one that decides whether the result lasts is the springback table. The first two hold the wall and reach the angle, and the third lets the next batch start where the last one ended.

Full specification — expand

System	A fabricated bed and bend head with a clamp die, a bend die and a bend arm; a pressure die with a boost; a wiper die and a mandrel; a carriage and a rotation axis; a hydraulic power unit with a reservoir, filters, relief valves and valves for the clamp, the pressure die, the bend and the mandrel; a controller that holds the bend table; encoders; interlocked guarding and an emergency stop; a tooling set cut to the tube and the radius; and trial bends and documentation before handover
The One Idea	Hold the wall. Hit the angle.
Why The Wall Has To Be Held	A bend stretches the outside of the tube, so the wall thins there, and squeezes the inside, so the wall can wrinkle, and the round section tends to flatten; the pressure die, the wiper die and the mandrel keep the wall round and even through the bend
Why The Machine Bends Past The Angle	When the bend arm lets go, the elastic part of the bend relaxes and the angle opens a little, so the machine bends further than the angle it wants, by an amount learned from trial bends on the customer's own tube and kept in the bend table
Standards	ASME B31.3 covers process piping, and PFI ES-24 covers pipe bending methods and tolerances. This page prints none of their limits or tolerances, and no edition year: those come from the standard the customer names. Approval of a bent part rests with the customer and the authority they name; none is claimed here
Configurations	A rotary-draw tube bender, a hydraulic pipe bender, and a bending cell with loading and checking
Scope Boundary	This page is the hydraulic tube and pipe bending machine, which bends tube and pipe round a die. It is not a hydraulic press, which forms a part between dies (see hydraulic press machine), not a stretch forming machine, which stretches a section or a sheet over a form (see stretching and stretch forming machine) and not a hydraulic power pack, which supplies an industrial machine (see hydraulic power pack). It does not decide the code class of a pipe, and it does not replace the fabricator's own procedure. Hot and induction bending, where the pipe is heated, is a different process. No certification or accreditation is claimed here
Status	Neometrix engineers hydraulic tube and pipe bending machines to order, and no delivered hydraulic tube and pipe bending machine is claimed.

Configurations

One method, three ways to build the machine.

The method, the safety design, the tooling logic and the proof are shared. What changes is the size of the tube, how much of the tooling it needs, and how much of the shop's flow the machine carries.

Rotary-draw tube bender

A mandrel, a wiper die and a pressure die boost, with feed and rotation axes

For tube where the wall is thin or the bend is tight: the full set of tooling, a carriage and a rotation axis, and a controller that runs the bend table.

Hydraulic pipe bender

A heavier frame and die set for larger pipe, with the angle read from an encoder

For larger and thicker-walled pipe: a stiff frame, a hydraulic cylinder or motor on the bend arm, a die set cut to the pipe, and angle control that allows for springback.

Bending cell with loading and checking

A bender with an infeed rack, a checking station and the bend data kept

For a shop that bends batches: tube loaded from a rack, bent to the table, and checked at a station against the drawing, with the data kept for the next batch.

And the part that is not equipment at all, yet decides all three: the tooling and the bend table. They are written from the customer's own tube, drawings and bends, not from the machine.

The drawings

A reference set, drawn as real CAD sheets.

Two sheets of one reference configuration: the hydraulic circuit of a tube bending machine, and its general arrangement with three details. They show the power unit and the four functions of the bend head, the bend head in plan, the machine in elevation, the section of the tube at the bend, springback and the bend table. They carry tags and letters only. Every force, pressure, size, radius, angle limit and time is fixed by design for the customer's parts.

Fig · 04 — Sheet 01, the hydraulic circuit: one power unit feeding the clamp, the pressure die with its boost relief valve, the bend arm with its encoder and the mandrel, in the style of the graphical symbols of fluid power. Reference configuration, tags only.

Reference drawing sheet two, the general arrangement and details of a tube bending machine. A plan of the bend head shows the bend die with the tube in its groove, the clamp die and the pressure die with their cylinders, the wiper die, and the mandrel with ball segments. An elevation shows the bed, the rail, the carriage and the rotation drive, the bend head, the power unit, the control cabinet with its emergency stop and the interlocked guard. An item list numbers thirteen parts. Detail A is the section of the tube at the bend, round before and oval after, with a thin outside wall. Detail B is springback, the angle after release against the angle commanded, with the overbend. Detail C is the bend table of length, rotation and angle for each bend. A title block stamped reference configuration, not for construction

Fig · 05 — Sheet 02, the general arrangement and details: the bend head in plan, the machine in elevation, the section at the bend, springback and the bend table. Reference configuration, letters only.

Every real machine is drawn for its own tube, its bends and its shop. These sheets are the arrangement and the order of working that a project set starts from. Approval of any drawing rests with the customer and the authority they name; none is claimed here.

PDF · two sheets

Reference drawings — schematic and arrangement

PDF · capability sheet

Tube bending machine — what Neometrix engineers

Where it is used

Wherever a bent tube is a part, and the wall at the bend has to carry its load.

The common thread is a drawing, a tube that has to keep its shape through the bend, and a shop that cannot afford a part that was almost right.

Piping fabrication shops

Process, power and marine piping, where a bent pipe saves a weld at every turn and has to fit the run first time.

Boiler and heat-exchanger shops

Where tube is bent into coils and returns, and the wall at the bend must still carry the pressure.

Maintenance and repair workshops

Where a replacement line is made from a pattern or a drawing, and has to fit without being forced.

Frame and structural tube makers

Where the part is judged by its shape and its finish, and the section has to stay round through the bend.

Watch

See it in motion.

A short walkthrough video of the Tube Bending Machine.

FAQ

Common questions.

Longer answers, for readers who want the reasoning.

Q · 01 What does a tube bending machine actually do?

It turns a straight length of tube or pipe into a bent part to a drawing. A clamp grips the tube. A bend die, turned by a bend arm, draws it round a radius. A carriage feeds the tube to the next bend, and a rotation axis turns it so that each bend lies in its own plane. A hydraulic power unit drives the clamp, the pressure die, the bend and the mandrel in turn, and a controller runs the bend table of length, rotation and angle. The machine does not choose the design of the part. That comes from the customer's drawing, and the machine is built, tooled and proved to carry it.

Q · 02 Why does the wall have to be held, and how is it held?

Because a bend stretches the outside wall of the tube and squeezes the inside wall. The outside thins, the inside can wrinkle, and the round section tends to flatten into an oval, and the tighter the bend the worse each one gets. So the tooling holds the wall. A pressure die pushes the tube into the bend die and gives the reaction to the bending moment. A wiper die supports the inside just behind the bend, which stops the wrinkling. A mandrel inside the tube keeps it round, and its position matters, because a mandrel set too far back lets the section flatten. A boost on the pressure die helps the tube through the bend and limits the thinning. A lubricant keeps the surface and eases the draw.

Q · 03 What is springback, and how is it corrected?

Springback is the difference between the angle the machine bends to and the angle the part keeps when the bend arm lets go. A bend is partly elastic, and the elastic part relaxes, so the angle opens a little. The correction is to bend further than the angle wanted, and the amount depends on the material, the wall and the radius. It cannot be taken reliably from a book, so it is learned. Trial bends are run on the customer's own tube, the result is measured, and the overbend is written into the springback table beside the part number. The next batch of the same tube starts from that table, and a change of material or wall is a reason to run the trial bends again.

Q · 04 Why a hydraulic drive, and what does the controller hold?

Because hydraulics give a large, smooth and controllable force from a compact unit, and they hold a position without drifting. One power unit closes the clamp, sets the pressure die, drives the bend arm and moves the mandrel, each in its own step and each held where it is. The controller holds the bend table: for every bend, the length to feed, the rotation to the next plane and the angle to bend to, with the springback correction. Encoders on the bend arm, the carriage and the rotation tell it where each axis is, so that the bend table is run the same way on the first part and on the last. The table is stored with the part number, so a repeat batch is a recall and not a new set-up.

Q · 05 Is this the same as a hydraulic press, a stretch forming machine or a power pack?

No, and the differences are worth stating precisely. The hydraulic press machine page covers the general frame press, which forms, straightens and assembles a part between dies. The stretching and stretch forming machine page covers stretching a section or a sheet over a form. The hydraulic power pack page covers the supply for an industrial machine. This page is the hydraulic tube and pipe bending machine, which bends a tube or pipe round a die. It does not replace any of them, and it does not claim what they claim a second time.

Q · 06 Has Neometrix built one of these?

We would rather answer this plainly than let a page imply otherwise. Neometrix engineers hydraulic tube and pipe bending machines to order, and no delivered hydraulic tube and pipe bending machine is claimed. What stands behind the offer is adjacent: Neometrix engineers a general frame press (see the hydraulic press machine page), a stretch forming machine (see the stretching and stretch forming machine page) and a hydraulic power pack (see the hydraulic power pack page). The pump, valves, cylinders, motors, encoders and controller parts are catalogue items, bought in, not invented. What Neometrix engineers is the machine around them: the frame, the bend head, the tooling, the hydraulic circuit, the guarding, the controls and the proof. So the honest position is that the machine is engineered to order, the neighbouring disciplines are in the building, and the first bending machine of this exact kind will be tooled and proved on the customer's own tube rather than taken off a shelf.

Q · 07 Which standard applies, and what can the machine not do?

ASME B31.3 covers process piping, and PFI ES-24 covers pipe bending methods and tolerances. This page prints none of their limits or tolerances, and no edition year: those come from the standard the customer names. The machine bends tube and pipe cold, round a die. It does not decide the code class of a pipe, it does not replace the fabricator's own procedure, and it does not do hot or induction bending, where the pipe is heated, which is a different process. This page claims no certification or accreditation. No force, pressure, size, radius or quantity figure is printed here, and approval of a bent part rests with the customer and the authority they name; none is claimed here.

Q · 08 What do you need from us to quote?

Six things, and most of them describe your parts rather than the machine. First, the tube: the material, the outside diameter and the wall. Second, the bends: the radius, the number of bends per part and the angles, ideally as a drawing or a bend table. Third, the straights: the longest length the machine must carry and the shortest it must grip. Fourth, the quality: the tolerance on angle and length, and the limits you set on ovality and wall at the bend. Fifth, the batch: how many parts, how often, and how many sizes. Sixth, the shop: the space, the power and whether you want loading and checking built in. From that we come back with a machine concept, a tooling list and test plan you can check, and a budgetary price.

The neighbouring pages, and how they differ from this one.

Three neighbours: one forms between dies, one stretches over a form, one supplies a machine.

↗ The press

Hydraulic Press Machine

The general frame press that forms, straightens and assembles between dies - where this page bends a tube round a die.

↗ The stretch

Stretching and Stretch Forming Machine

Stretches a section or a sheet over a form - a different way to curve a part from drawing a tube round a die.

↗ The supply

Hydraulic Power Pack

The hydraulic supply for an industrial machine - where this page is a machine that carries its own power unit.

Browse all Neometrix product lines.

Get a quotation

Tell us the tube,
and the bend it has to make.

The projects desk replies within two working days with a machine concept, a tooling list and test plan you can check, and a budgetary quotation. Write to [email protected] or use the form.

Enquire — tube bending machine Capability sheet (PDF) +91 7777 876 876

ISO 9001 / 14001 ENGINEERED-TO-ORDER CLASS — HYDRAULIC TUBE AND PIPE BENDING MACHINE PART · TOOLING · MACHINE · SAFETY · BUILD · PROVE — HOLD THE WALL. HIT THE ANGLE. ENGINEERED IN NOIDA · INDIA