Tube Bender

An efficient and effective cleaning of straight or bent tubes, particularly their inner surface, poses an engineering challenge. Though, conventionally methods of using hot water and alkaline agents have been in use, the results are far from satisfactory. Varying shapes, diameters and `openings of tubes make effective cleaning a very slow and difficult process due to viscosity of the lubricant used for protecting the metal. The technology that employed dip tanks of water solutions or spray techniques resulted to very low output, thus necessitating the needs of an alternate effective and economical system. That prompted the developments of solvent cleaning systems to derive the benefits of increased production of efficiently cleaned components.

A hermetically sealed closed circuit system that uses an appropriate solvent is ideal for washing of industrial components on a mass scale. The quality of cleaning and the subsequent drying of the components is of highest possible level. Further, the unit cost of cleaning is also very low. Such systems are designed to remove the toughest and thickest of contaminants. By making use of heated sprays and immersions in a definite sequence with the accompanied application of ultrasonic techniques during immersion and vapor rinsing, closed circuit sealed solvent system deliver efficient results of very effective cleaning. Moreover, the use of heated blow-cycles accompanied with vacuum drying delivers absolutely dry components, irrespective of their positioning in the system.

Washing with a mixture of hot water and alkaline soap is not as effective; rather it is just about fifteen percent as effective as washing with a solvent like Perchloroethylene (also called PERC) because the latter successfully breaks the surface tension between the metal and the soil six times more efficiently than the former. This characteristic helps the ultrasonic action (that is applied to the solvent that is still in submersion) to further break away the surface tension between the part and the impurities sticking around it, thus ridding the part of its soil and rinsing away the same. Every cycle of the cleaning operation is confined within the same sealed chamber that may have one or more baskets of loaded tubes conveniently oriented within that chamber.

At the very beginning of the cycle, the door gets closed , followed by jets of hot solvent under moderate pressure that are sprayed on to the parts. The action of cleaning is performed by the sprayed jets of solvent under pressure. This action successfully removes up to 90% of soil from the parts. The solvent, that has dissolved soil in it, is simply drained out of the process area, while the process of spraying is continued, and is diverted to a distillation device that forms a part of the system, and boils the solvent to a vaporous state. The soil continues to remain in the still and is removed subsequently whereas the vapor is sent to a chiller for condensation to get a clean solvent in liquid form and is used subsequently. During the whole operation of the system the process of distillation is continued.

In the second stage, the tubes are fully submerged in the process chamber.
Simultaneously, an ultrasonic mechanical application removes the left over contaminations from the internal and external surface of the tubes.

The final stage of cleaning involves direct vaporization of parts by means of solvent vapors within the chamber. The vapors that come from the still are not sent to the chiller straightaway for final condensation, but are diverted to the process chamber. Here they are used for providing the final rinsing to the parts and get condensed thereon, thus removing any leftover pollutants on the parts. Finally the parts are moved to a dryer. This action facilitates recovery of almost the whole of solvent from the parts. To full fill the norms of environmental regulations charcoal filters need to be employed in some of the machines.

Inclusion of tubes in many products is an engineering practice that can’t be avoided. Tubes form an essential part of any refrigeration system. These are again necessarily used in heater cores and exhaust manifolds. Unless their interior is cleaned thoroughly, the efficiency of the system will be adversely affected. The conventional practice of cleaning them with soap and water is inefficient as it fails to clean to the desired level, particularly the internal surface of the tube. Apart from the technique or the system employed, it is the medium employed, that is water and soap that just is incapable of delivering the much needed degree of cleanliness.

In the advanced system described here there is no need to shift parts from one bath to another as it is the solvent that comes to the process chamber. Visualize the advantage of this action. As there is no shifting of parts from one bath to another, there is absolutely no chance of the bath getting contaminated, which can’t be avoided in the conventional system of cleaning.

A fixture indexing system involving conveyors necessitates the incorporation of nests for holding the parts in a particular predefined angle and position to facilitate the direction of spray to the internal sidewalls for an efficient cleaning. Consequently, you have to make fixtures for holding the tube, depending on its diameter. That in effect means having different nests for different sized tubes. This is necessary not only for adequate cleaning, but also for efficient drainage to get the desired level of drying.

When using the process of submersion for cleaning, it’s important to have alkaline cleaning medium of appropriate strength, lest it should harm the not so tough metals used for making certain tubes. In such cases it becomes a tricky affair to drain out water from inside the tubes before a basket of tubes could be moved from one bath to another for performing the next action of rinsing, cleaning or drying. If you decide to use single piece-flow, the different designs of fixtures for nests needs to be changed that slows down the production process.

In the light of above it can be well concluded that a system that employs solvent in a closed circuit is the most effective and adaptable. It can successfully be employed for many applications of which tube cleaning is one.

Any manufacturing process necessarily involves the application of some machines or tools for its execution. Of the total time that is needed for execution of one cycle of manufacturing operation, a not so insignificant part of time is taken in making the necessary adjustments of the machine to be operated or the material to be processed. In manufacturing or engineering practices, this time is referred to as “setting time/set-up time”. As can be understandable, cutting down of this time would make available more time for effective production that leads to an increased output.

The process of bending tubes and pipes is very sensitive and time consuming. CNC tube bending machines were primarily devised to cut down on set up time and to maximize production. As with any other engineering product, continuous technological developments have constantly been pouring to improve upon the design and features of a CNC machine. The looks and functions of the latest machines are very much different than the ones which were originally designed a few decades ago.

There are many manufacturers of CNC bending machines and every machine or model has some outstanding feature to suit a customer’s specific needs. Some of the manufacturers have recently introduced CNC tube bending machines with electrical servo-drives on all axes and these come with a single or multi stack version.

CNC tube bending machines with multistack benders enables bending without changing the tool. If you are unable to use multistack tool for reasons of safety, you may try an automatic clamp die changing system that can easily house up to eight clamp dies.

The CNC tube bending machines perform excellent bending operations that can be programmed and offer boosting via the transport carriage in conjunction with the boosting in the area of pressure die. The boosting helps to minimize thinning of wall on the outer bend that further facilitates narrow bending. You can easily achieve a radius of less than 1 x OD. The Other operational features and specifications of a CNC tube bending machine may include any or all of the following:

* An MMI multi-control 2020 system
* TFT monitor
* Touch-screen
* Plausibility verification
* XYZ coordinates recalculation into bending parameters
* Flexible programming
* Multitasking
* 3-D displays
* Integrated modem
* Access to the world- wide web

The integrated modem and access to the internet work successfully provides the best remote maintenance and technology support.

The CNC tube bending machine is provided with a bending template that facilitates the bending of pipe as per requirements. The straight portion of the pipe is supported on a pipe that support-rail carries. Its height can be adjusted to suit a particular position. The height adjustment is achieved by a drive. This enables the adjustment of the pipe-supporting rail to a height that is dictated by the CNC control unit. Before actually bending the pipe, the height to which the pipe has already been moved is checked by a functioning program that in turn is governed by a full set of tool data that has been fed to the control unit.

Many generations have been adopting different techniques for bending of metals and other materials. We have all been informed of the use of metals, particularly steel for construction of buildings thru ages. Present day construction of buildings employs a large volume of steel in different forms.

Modern architecture and construction engineers would find it difficult to create even simple buildings or staircases in the absence of curved metal beams, pipes, tubes or angles and channels.

Construction of all those skyscrapers, airports and museums that you often see and get impressed by their unique designs, necessarily need curved steel for being made in that shape and design. Walking down the street did you ever wonder how a tough looking metal like steel be made to bend to suit man’s requirements without having to make any compromises on its characteristics of strength and sturdiness.

It may be a bit difficult to guess the shape of steel used for construction of any building as it is not visible, being covered by concrete and other materials. But how about imagining the handle bar of a bicycle or an exhaust pipe of you car? Here is an opportunity for you to get an exposure to different techniques or rather present day engineering practices followed for bending of materials, particularly metals.

Rolling technique for bending of metals:

One of the least expensive best known methods of bending metals is by rolling. The technique can be applied to metals, plastics and glass. Rolling employs the application of pre-made dies of specified size that adjusts to steel tube, pipe, angle, channel, bar or steel beam that revolves at the same peripheral speed but turning in opposite direction. As the metal is passed thru the rolls, an appropriate pressure is applied to bend the tube or beam to the required radius.

Rolling is considered worthwhile and effective when you want to achieve higher bends, and the process can be successfully employed for producing bends up to 360 degrees. This is the most common practice adopted for bending of steel and getting it to coils. Another good in everyday life example in everyday life is a spiral staircase.

tube bending

There are different types of rolling processes. Hot rolling is possible above the temperature of re-crystallization. Steel is most often hot rolled whereas non-ferrous metal structures are cold rolled.

As this technique of rolling uses readymade dies and often required little set-up time, it works out more economical than most other techniques. It is a preferred way of achieving the results.

Mandrel to bend metal

The practice of using mandrels to achieve bending is fairly well known. In this case a metal shaft often called mandrel is fitted inside the steel tube or pipe. As the mandrel is moved, it bends the metal around an appropriate sized die to get the specified radius.

Mandrel is ideally suitable for bending of pipes or tubes with large wall thickness or those requiring a tight radius as it are detrimental to metal ripping.  Mandrels can be used for bending of steel tubing up to 180 degrees. This gives uniform bend all the way up and down the pipe or tube. Obviously, this process is not very helpful for bending of metal beams or sheets; nevertheless this is the most frequently technique employed for bending of exhaust pipes, molten glass and in very few cases for jewelry.

Press to bend metal

Here is another method for bending metals. Here the material to be bent, be it a pipe, tube or a channel, is fed thru a press which applies pressure along the predefined points on the material till the require angle of bend is achieved.

This method is often employed for bending of heavier beams, channels, bars, pipes and tubes (of 24inches or more) that do not require a very tight bend or radius. This is not as frequently practiced a method as rolling or the one employing the use of mandrels, but is largely used for bending of load bearing steel structures often employed in civil construction and engineering. All the tall buildings and long bridges that one often sees necessarily are required to use steel bent thru this process. Roofing of such large buildings and malls would be other applications of such steel.

Table forming to bend metal

Table forming is anther technique for bending of metals. The steel pipe, or beam or tube is laid out straight and its ends are pulled by using an appropriate sized die to achieve the needed radius.

This method is generally adopted for bending of smaller and heavier steel tubes, pipes, bars, channels, and steel beams that need a tight radius.

So, next time you watch a new building or even equipment that you might be using in your everyday life, allow you imagination run wild and keep guessing how and by which technique it could have been made to look in its present bent shape!