Tube Forming Machines

Tube forming differs from tube fabrication, which is the manufacturing of tubing, and is considered to be a secondary process to tube fabrication. The machines that perform tube forming processes must be able to maintain a high level of accuracy due to the complexity of the various shapes required. As a result, tube forming machines are generally either dedicated machines or automated manufacturing cells. While dedicated machines are built for a specific job and thus, cannot accommodate any design changes, automated manufacturing cells are able to provide high production rates as well as the ability to be versatile in design. Some examples of applications and industries that utilize tube forming machinery include: marine, for use in exhaust products, heat exchangers, piping systems and more; automotive, to be used for structural components, coolant systems, exhaust manifolds and more; industrial manufacturing, for applications such as various automation equipment and tubing assemblies; and medical, for use in complex components such as glass capillary tubes, epidural needles and arthroscopic drivers.

There is a large variety of tube forming machine types, since there is such a range of tube forming processes available. Some common examples of tube machinery include bending machines, tube cutting machines and tube end forming machines. Bending machines, also referred to as tube bending equipment or tube benders, are used for the primary function of curving and twisting lengths of tube. The particular method used to bend the tube often varies depending on the intended application; some common types of bending include rotary, mandrel, and roll bending. Not only able to be performed on tubing however, pipe benders are also available for a similar process on piping. Also known as tube cutters, tube cutting machines are used for the purpose of producing a square or circular end that is free from burrs. Tube cutting machines must be very precise because if too much pressure is applied to the cutting wheel at one time, deformation or burring of the tube end may occur. In addition to producing an end, tube cutting allows for various lengths of tubing to be produced, depending on the needs of the specific application. More specifically intended for the production of an end, tube end forming machines are vital equipment for many industries. Other functions of tube end forming machines include end reduction, flanging, chamfering, end expansion roll beading, notching, and flaring.

Additional examples of commonly used types of tube forming machinery include tube swaging machines, tubing rollers, tube mills and tube notchers. Tube swaging machines, often referred to as simply swaging machines, are used for the purpose of permanently joining tubes together by putting the tubing under high pressure or by pressing them into a die. Unlike most types of metalworking, which rely upon heat to form the metal, tube swaging machines are more likely to use cold metalworking processes instead in order to form the metal as desired. Tubing rollers, or tube rollers, are more of a tube fabrication machine than a tube former as they are used in order to roll strips of metal into tubing. Tube rollers can provide a variety of tubing types such as large diameter tubing, small diameter tubing and even some forms of piping. Tube mills or tube mill equipment are essentially the same as tube rollers as they also produce tubing or piping by means of taking a strip of metal and continuously roll forming that metal strip until the edges of the strip meet together at a weld. Tube mill is a much more common term to describe this type of tube forming machine than tubing roller or tube roller. Lastly, tube notchers are essential tube forming machinery because they provide the important function of creating a notch, which is a cut that is vertically down and perpendicular to the surface, in the tubing or pipe.

Some less common types of tube forming processes include threading, hydroforming, tube flaring, coining and nitinol heat setting. For the process of tube threading, machines are used in order to produce raised helical ribs on the end of the tube. The purpose of external tube threading is to allow the tubing to be easily connected to other pieces of tubing with internal threading. Hydroforming, while not specifically a tube forming process, is used by tube forming machines in order to enable severe shape deformation of the tube. As a forming process, hydroforming utilizes fluid pressure in order to shape the tubing to the die and is used because it produces strong tubes of uniform thickness. A type of end forming process, tube flaring is performed by tube end forming machines and shapes the end of the tubing into a funnel shape that is then able to be easily held by a threaded fitting. Requiring the use of a power press, coining is a tube forming process in which custom tooling and dies are used to coin, which means to flatten, the tubing. Angles or radii can both be achieved by tube coining machinery at the corners of the tube end by means of the tooling design. Finally, nitinol heat setting is a very specific process that is performed on nickel titanium, a shape-memory metal alloy consisting of 50% nickel and 50% titanium. In nitinol heat setting, the tubing is forced through a die into the desired shape and then baked at high temperatures a number of times in order to create a heat-set shape.

Tube Forming Machines Types

• Bending machines are CNC machines used to bend metal tubes.
  
• CNC machining is a type of machine used in the draw bending process that is quick, reliable, dependable, fast and flexible and produces precise, repeatable high quality bends. CNC machines are simple to set up and program and are capable of having a large quantity of specifications entered into the system to produce complex bending geometries.
  
• Hydroforming is a process in which fluid pressure is used to form the tube to the die, allowing for severe shape deformation. Hydroforming typically produces strong parts of uniform thickness.
• Pipe bender are a type of machinery used in the forming of pipe into various shapes, specifically bends which are angles of 2º to 90º, under normal conditions.
• Swaging machines use high pressure to permanently join tubes.
  
• Threading is the process in which raised helical ribs are formed on the end of a tube. Threading can be accomplished by either keeping the tube stationary and rotating the machinery or by rotating the tube on stationary machinery.
  
• Tube benders are machines used in order form tubing into the shape or the die which is an angle, the range of which is from 2º to 90º, also known as a right angle.
• Tube bending equipment includes all those machines used to bend, swag, and form tubes.
• Tube cutting machines are used in the tube forming process of cutting, which is the act of removing a piece from the main part of tubing or piping.
• Tube end forming is a process in which the end of a tube is formed to exacting specifications for a particular use.
• Tube end forming machines increase or decrease the diameter of a pipe at its end.
• Tube machinery refers equipment that is used in the forming of tubes, or the process of altering tubing into complex shapes.
• Tube mills are a type of tube forming machinery that takes a continuous strip of metal or other material and continuously roll forms that material until the edges of the strip meet together at the weld station.
• Tube notchers are a type of tube forming machine that functions to produce notches, which are a vee-shaped indentations, in tubing or pipe.
• Tube swaging machines use high pressure to connect tubes together at a permanent joint.
• Tubing rollers also known as tube rollers, are a type of tube forming machinery used similarly to tube benders, thus creating an angle in the tube or pipe of up to 90º.

Tube Forming Machines Terms

Ampco - An aluminum-bronze wear surface used for mandrels and wiper dies for bending stainless steel, specifically.
 
Ball - A component of the mandrel assembly that supports the arc of the bend of a tube in order to keep it from flattening after it has passed through the point of bend.
 
Bend Data - A term that refers to the basic elements of motion that must be programmed into the controller of a CNC tube-bending machine in order for the tube to be bent.
 
Bend Die - Sometimes called the "bend form" or the "radius die," it is the primary tool of a rotary-draw tube-bending machine, against which the tube is placed and drawn around to produce a bend.
 
Bend Radius - A general term referring to the arc of the bend itself but which does not precisely specify the radius. Bend radius can refer to the inside radius, the centerline radius or some arbitrary reference point, though it is typically measured from the centerline.
 
Bender - A mechanical device that is used to form a bend or arc in a straight length of material. Bender also refers to a company that performs this service.
 
"C" Style Tooling - A drop-in segmented tooling that has either a set of dies that only reduces or fingers that only expand.
 
Cold Drawing - A tube bending process that does not involve the use of heat. Cold drawing is used to obtain smooth surface finishes, reduce the wall and/or the outside diameter and achieve closer tolerances.
 
Crush Bending - A non-mandrel tube bending process in which the tube is stretched over a crush knob located in the cavity of the bend die, eliminating any wrinkling or buckling that may occur in the tube in the absence of a mandrel. Crush bending is typically used on non-round tube bends.

Degree of Bend (DOB) - Sometimes called the "angle," it is the measurement of the degree to which the tube is bent.
 
Drop-in Style I/O Segmented Tooling - Six- or eight-segment dies and fingers in a housing, a self-contained barrel, which can be quickly and simply dropped into or removed from a machine to provide a quick changeover to another tool set. The dies are close on the outside of the tube, and the fingers are open on the inside of the tube.
 
"E" Style Tooling - Ram forming tooling that consists of clamping dies and ram tools. The clamping dies are used to hold the tube during the forming cycle.
 
Elongation - The increase of the length of a material during the bending process, expressed as a percentage of the initial length.

Hot Bending - Any tube forming process that uses heat.
 
Inside Diameter (I.D.) - The diameter of the inside of the tube.
 
Mandrel - A part of the tube-bending assembly that provides support to the inside of the tube in order to prevent the tube from buckling or necking.  A mandrel may not be necessary if the wall is thick enough.
 
Outside Diameter (O.D.) - The diameter of the outside of the tube.

Plug Drawing - A cold finishing operation that produces a precise outside diameter and wall tube. In plug drawing, the tube is drawn through a die over a plug.
 
Press Bending - An inexpensive and fast method of bending that is suitable only for applications in which tube walls are relatively heavy and centerline radii are large. Press bending produces reduced bend quality, because it is impossible to fixture mandrel tooling inside the tube or wiper tooling to control the flow of material.
 
Ram Bending - A process in which a tube is placed in a die and hydraulic ram. The ram, containing half of the dies, presses into the tube and pushes it around the radius.
 
Roll Bending - A quick and effective method of bending a tube by feeding it through a triangular arrangement of rollers. Roll bending forms extremely thick walls and large radii from the material that exceeds the capability of rotary draw benders.
 
Rotary Draw Bending - A principal method of tube bending in which the material is drawn around a rotating bend form or die. The forward tangent is rotated, while the back tangent is held in place by a pressure die, allowing for the use of mandrel and wiper tooling.
 
Sink Drawing - A cold finishing operation in which a tube is pulled through a die without using a mandrel. Sink drawing is used to obtain the exact desired diameter and/or to improve mechanical properties of the tube.
 
Sizing - Forming the end of the tube to meet preset specifications of roundness and concentricity.
 
Springback - The response of the tube after the stress of the bending process has been removed. Tubes can be bent over the specified DOB, so that they will open up to the desired degree or bend.
 
Tangent - The excess material on either end of the arc or bend of a tube that can be cut off after the bending process.

Tube Flaring - An end forming method in which the end is formed into a funnel shape so that it is able to be held by a threaded fitting.
 
Wall - The thickness of the tube or pipe wall, usually expressed as "nominal" or "minimum."
 
Wiper Die - Also called "shoes," it is used to prevent the wrinkling of the tube during the bending process. A wiper die is necessary when the resistance of the tube to compression is high.
 
Wrinkle - An unwanted fold, crease or ripple formed on the pipe surface during the bending process.