The use of coiled tubing is becoming more popular within Automotive and HVAC industries. The benefits are known: Coiled tubing brings logistical savings, less wasted material and it allows faster production.

The interesting matter is that today there are available coiled tubing that have traditionally been supplied on straight lengths due to large diameter or material characteristics. This means, that small diameter steel tubing (4-12 mm) as well as large diameter (15-25 mm) aluminium and copper tubing can already be supplied on coils. Some manufacturers are even joining tubes together just to make longer coils. Such tubes are typical for Automotive Industry where they are used for making brake, fuel, power steering and air-conditioning parts.

Picture 1. Large Aluminium tube coil

Picture 2. Large automotive brake-line tubing coil

Such a large coils have set new requirements for decoiling and tube cut-off systems. To better meet these new requirements, T-DRILL has developed a completely new chipless cut-off product and dedicated decoiling equipment that can fully meet al these challenges.

Chipless tube cut-off basics

Chipless cut-off has unquestionable advantages what comes to tube cutting. The method makes no chips and noise level is low if compared to other tube cut-off methods.

T-DRILL's tube cut-off method is also chipless. It is rotary cutting with so called "Pull-apart" system. This means that first the cutting disk is penetrating tube wall about 95%. After that the cut-length is separated by pulling it apart. This eliminates the I.D. reduction that would happen if the blade would go through the tube wall.

With this feature, the secondary operations are easier to carry out since the cutting quality is usually good enough for the secondary operations without deburring or chamfering tube ends. The method also allows easy chaining of different processes like cutting + endforming/bending. And yes, tubes requires no washing since the lubricant is biological and evaporative. Brazing or welding can be done even if there is still some left.

The totally new idea that T-DRILL is introducing now is the feeding system which is based on Linear Motor technology.

Linear Motor Principles

Linear Motors provide direct linear motion without mechanical linkages, such us ball screws. A permanent magnet linear motor can be thought of as permanent magnet rotary motor, whose stator and rotor has been cut along a radial plane and unrolled, so that it provides linear thrust. The same forces of electromagnetism that produce torque in rotary motor are used to produce direct linear force in linear motors. The result is a flat linear motor that produces linear force, as opposed to torque, because the axis of rotation no longer exists.

The Motors are typically supplied as construction kits. They include:

• The primary part contains the 3 phase coils.
• The secondary part contains the magnets.
• Machine carrier
• Linear measurement system

Drawing 1.Linear Motor principles

Linear Motors offer the following advantages over conventional solutions:

DIRECT DRIVE - No backlash from leadscrews or other mechanical gearing and linkages.

NON-CONTACT - Force is generated through an air gap, so there is no metal-to-metal contact and no wear.

SIMPLICITY - Only one moving part, no mechanical linkages.

TRAVELS - No travel limits, as long as flatness and straightness are maintained.

VELOCITY - Linear motors provide low to high velocities. From 1 micron per second to 350 m / min

ACCELERATION - Up to 10 G's and more.

SMOOTHNESS - Provides smooth operation because they don't rely on mechanical linkages.

ACCURACY AND REPEATABILITY - Submicron accuracy when coupled with an appropriate feedback device. ±0.5µm positioning accuracy achievable.

STATIC FORCE - Static force up to 22000 N/motor

MAINTENANCE - Just about maintenance free.

LIFE EXPECTANCY - Under normal specified operating conditions, life expectancy can be indefinite.

TCC-25-LM - Linear Motor Cut-Off machine

T-DRILL new chipless cut-off machine - TCC-25 LM - is using the above described Linear Feeding system for cutting tubes to length. This new technology provides very fast and accurate cut-off for various cut-lengths (< 6000 mm). It also has the power that is needed to feed and straighten tubes up to diameter 25 mm or coiled steel tubing up to 12 mm diameter.

Until now T-DRILL has used pneumatic hitch-feeding system. But the thing within T-DRILL is to move ahead and meet challenges. So, finally it was the time to do consider about using Linear Motors for tube cut-off and now it is done. With TCC-25-LM. Finally the heavy use of pneumatic air can be put to history.

Picture 3. T-DRILL TCC-25-LM Linear Motor based chipless cut-off

With tube cutting operation it is impossible to use full capacity from Linear Motors that they could provide. Like cut-length tolerance is set "only" to +/-0.01 mm. But the reality still is +/- 0.1 mm since there are limitations that just tube cutting process will set. The same concerns feeding speed and accelerations. By experience T-Drill has found out that 3 m/s feeding speed and acceleration 25 m/s2 are normally the maximum values - which, if keeping in mind the cut-quality and length tolerances - are very high compared to any other method.

Picture 4. Tube feeding system based on Linear Motor technology

Multiple different cut-lengths automatically with high accuracy

What makes TCC-25 LM special is the ability to cut several cut-lengths automatically based on touch screen parameters. These different lengths will be separated automatically after cutting operation by the diverting table.

The automatic cutting of different lengths is useful function when there is an assembly that requires several cut lengths from the same tube diameter. Another useful application is to have single TCC-25 LM for cutting different length tubes for several bending or endforming machines that are all making different parts.

Picture 5. Multiple cut-lengths automatically based on touch screen input

User friendly controls

The operator interface is touch screen control panel. It includes advanced functions and diagnostics which are making TCC-25 LM very easy to use - Even for non-skilled operator. From this control panel the operator can change tube cutting and general machine settings parameters.

Picture 6. Touch screen controls

Straightener with quick changeable rolls and digital read-outs

In order to make tube straightening as easy as possible, T-DRILL has developed straightener that allows quick change of straightening rolls. Another improvement is the use of digital read-out for adjustment of the rolls. Everyone who has been dealing with tube straightening knows how tricky thing it van be to adjust tube straightener. T-DRILL is now using digital read-outs for straightener setting. This will give lot of help already when the basic setup can be recorded.

Another matter is "quick changeable rolls". This is important feature if there is a need to change tube diameter often. This system is just matter of "pushing a button" to release straightening roll for changing it to another one

Picture 7. Quick changeable straightening rolls

Picture 8. Digital read-out helps with straightening setting

Horizontal decoiler for heavy coils

Linear Feeding, just like any other "hitch feed" method is based on three operations: Acceleration, feeding and stopping. In order handle this kind of "Feed-Stop-Feed-Stop" operation, the decoiling equipment needs to be able to accept all these high accelerations and stoppages while still keeping the tube tight to avoid coil jamming and tube damages. The new decoiler design meets all those requirements

Picture 9. Dedicated decoiling equipment for heavy coils

Auxiliary equipment

TCC-25 LM can be equipped with NDT (Non Destructive Testing) or color detecting equipment. NDT equipment can be used for detecting defects and/or joints on coiled tubing. The advanced software will remove these bad sections from the coiled tubing automatically during cutting process. It also makes sure that in such a cases the wasted tubing will be minimized.

Picture 10. Non Destructive Testing (NDT) Equipment

If needed, the tubes can be marked or labeled by ink-jet/laser printer.

Cut-off with integrated endforming using Linear Motor technology

Beside normal cut-to-length systems, T-DRILL has used the Linear Motor technology for cut-off machines with integrated endformer. While all the Linear Motor feeding benefits are explained earlier, there is one important matter that needs to be explained when thinking of in-line cutting and endforming. This is change over time. Linear Motor based feeding is accurate enough, that machine can automatically cut and endform multiple cut lengths. Until now this kind of length setting has been time consuming work to do - sometimes it has taken an hour to carry out. With T-DRILL's Linear Motor based cut-off & endforming system, it takes no extra time at all.

Picture 11. Chipless Linear Motor based tube cut-off with integrated endformer

Summary

It is likely that the industries will be using coils more frequently instead of straight length tubes. Coil sizes will also become larger. Tube diameters on coils will also be larger and coiled steel tubing will be coming to use more.. With TCC-25-LM Linear Motor based cut-off, dedicated decoiling system, new straightener with quick changeable rolls and advanced software T-DRILL can meet the most of these demanding cut-off applications.

For further information please contact:

T-DRILL Oy
- Tel:+358-6-4753 333
- Fax: +358-6-4753 300
- WWW: http://www.t-drill.fi
- Email.