Tubo Roll and Pipe Roll Bending Machines

The tube roll and pipe roll forming industries will benefit greatly from buying Kaast tube rolls and pipe rolls. Kaast is manufacturing high-quality tube rolls and pipe rolls for both tube rolling and pipe rolling producers worldwide, with great service to back it up.

Our angle roll bending machines outperform the angle rolls made by other manufacturers, leaving our customers highly satisfied with their Kaast angle rolling machine purchases. At Kaast we take pride in providing the finest-quality tube rolling, pipe rolling and angle rolling machine tools at very competitive prices, with a dedication to our customers first.

Pipe and tube ring roll benders comprise 3 rolls on separate shafts that roll the pipe through the rolls while the top roller exerts downward pressure on the top roll to deform the pipe. Ring Roll, Pipe and Tube benders are available in 2 or 3 driven roll machines, with either manual adjustment or hydraulic adjustment of the top roll.

Common use of Tube Rollers and Pipe Rollers

Ring roll bending is used for bending pipe and tube to large Center Line Radius, i.e. to large circumferences, and roll bending is typically used for awning manufacture, drum rolls, frames for barbecues, and other round items with a large Center Line Radius.

How to bend Tubes and Pipes

Pipe rollers have the same sort of shoe, or die, arrangement as benders, but have the pair of metal rollers on the bottom. They have ball bearings inside so they roll smoothly. The top single shoe is fixed to a shaft so it turns with a wheel. As you feed the pipe through, you slowly shape the metal pipe into a smooth long curve. You feed some pipe into the machine and lower the top roller while feeding it through.

This is a slow, deliberate process in which you adjust the roller down each time. The curve you get will not have any bumps, because the roller is rolling out the bumps as it curves the metal pipe. The pipe itself actually gets longer as you run it through the roller, depending upon the bend you are making.

Profile Rolling Quick reference

Advice for bending

To achieve a reduced bending radius in only one pass, do the following:

1. Insert the material between the rolls and have the Iower rolls in tangential position (fig. 1)
2. Have the profile backward (fig. 2)
3. Raise the right Iower roll a little (fig. 3)
4. Have the material about 50/80 cm. forward (fig. 4)
5. By the inverse rotation have the material backward (fig. 5)
6. Raise the right Iower roll again (fig. 6)
7. Repeat the bend beginning which will be more marked (fig. 7)

lf necessary, repeat once or twice until you have the required diameter.

To obtain complete circles with bent ends as per (fig. 1) you can instead do the following:

1. Cut the bar to be bent about 10/20 cms. longer: (fig. 2)
2. Bend the part until the ends meet (fig. 3)
3. Cut the ends that are not bent (fig. 4)
4. Pass the ring between the rolls until the ends meet (fig. 6)

The result will be an almost perfect circle with an exact diameter.

Recommended bending materials

All materials can be bent by our machines, but results will be determined by their nature. For example, steel tends its original position, due to elasticity.

Unless resistance is uniform, the diameter of circles will be uneven. Unless bar size is consistent, the circle diameters obtained will also be irregular (even if the differences are no more than a few tenths of a millimeter).

In the case of angle or other sections which need straightening, corrections may be found to be irregular as the straightener may exert too much or too little pressure.

To the extent feasible, workpieces should be clean, free from rust and oil, and dry. Finally, we recommend that only straight bars be used, as distorted bars may over or under-bend and the results will be affected.

Preparation of workpieces

All materials bent edgewise and sections having a flange bent edgewise should preferably be chamfered to make it easier to insert the workpiece between the rollers. When sections require straightening as well as bending, another chamfer is sometimes needed so that the section can leave the straightener.

Example of section prepared with chamfer

T-section prepared for bending with outside flange.

Ángulo-section prepared for bending with internal flange.

Flat-section prepared for edgewise bending.

Ángulo-section prepared for bending with outside flange (notice the two chamfers: the large one to leave the roller, the small one to leave the straightener).

Setting up the rolls

The three rolls of our bending machines do not have the same diameter, the small one must be set up on the central shaft (inside the bend) and the other two on lower shafts.

It is necessary that the rolls are set on the machine in the right position according to the type of profile you have in mind to bend.

This will prevent excessive efforts and unnecessary twist. When bending normal sections like “T” iron or angle iron, the leg on the edge must never reach the key settled on the driving shaft.

If you wish to get a better bending result, insert a spacer between the two half-rolls with an exact thickness and diameter to support the edge’s bent leg.

Moreover it is necessary inside radiused walls of profiles to find a roll with radiused corner, when bending.

In sectional bending, the groove of the roll must be settled as wide as the thickness of the profile which has to run slightly pressed.

In bending flat iron on the edge, the groove of the upper roll must be prearranged 2-3-4 mm. larger than the thickness of the material.

Bending general instructions

The following is the recommended procedure for operating the bending machine:

1. Insert the bar between the rolls from left to right, and check that the grooves are aligned. During this operation, the rolls must be in a rest position, without bending the section.
2. Act on the left handwheel, keeping the bar between the rolls in order to have the bar in a horizontal position, and support it by a stand.
3. Remove the bar and turn the right handwheel to achieve the estimated correct setting for the desired radius.
4. Start up the motor and bring the section near the rolls (from left hand to right). The three rolls will draw the workpiece forward and move it without the need for manual intervention. If this does not occur, either the rolls are too close, or the chamfer is not long enough. However, you can overcome this difficulty as follows.
5. Lower the right roll until the section is bent (does not matter if little) for a length of about 15 cm. Operate the reversing gear, move the workpiece backward and lift the right roll. Execute the bending again, and if necessary repeat this operation until the bar enters the rolls in the desired position. Items 4 and 5 are surplus using hydraulic models.

How to get the desired diameter

Prepare three or four cut down sizes of the workpiece to be bent, with a length of about 40–50 cm. Insert one into the machine and execute a test bending.

There are two possible results:

1. The radius is correct: no problem is encountered and work can continue.
2. The radius is too wide or too narrow: suitably correct the right roll and insert another cut down size; repeat the test until you get the desired radius.

For these tests use rectilinear cut down sizes; never use bent pieces nor bent pieces successively straightened.

We repeat that precision and continuity in the radius depends only on evenness and homogeneity of the workpiece. As this is sometimes difficult to get, bent pieces have to undergo a successive correction.

Position 1

Bending of flat sections in edgewise position

To obtain a small circle, we suggest having the workpiece suitably chamferred. The rolls have to be settled as per positions shown in Figures A, B, C and D, and this is according to the quality, the sizes of material and the diameter you wish.

Please note;

• Fig. A: is only fit for thick sections.
• Fig. B: is only fit for flat, high and thin sections.
• Fig. C: in this position are shown the rolls settled to obtain small diameter circles.
• Fig. D: this position must be avoided as rim speeds of rolls have very different values: in the points of touch with the profile.

In case during bending there are some vibrations, we suggest taking off the small key from one of the three rolls; it is better from the right lower one.

In case of fig. a, b, c, the groove of upper roll must be settled 2-3-4 mm. larger than the thickness of material. This value is inversely proportional to the bending radius.

Position 2

Bending section flat on flat

The rolls must be in normal position with the disks of each roll joined each other.

In case of continuous work we advise to equip the machine with rolls having a groove as large and deep as the section to be bent. In this kind of work, the ends not fully bent may cause some difficulty. This inconvenience can be repaired in several ways according to the case. Please contact us.

Positions 3 and 32

Bending of square sections

Set the rolls in normal position as previously stated, (pos. 2).

In case of continuous work it is good to equip the machine with rolls having a groove as large and deep as the sections to be bent.

To obtain small circles, it is necessary to chamfer the workpiece, to make it easier to insert it between the rolls (the above operation is not necessary for hydraulic models).

When bending square sections, if the machine is too noisy, this is due to rim speeds which do not correspond to the internal and external circumferences of the circle in work. To overcome this difficulty, we suggest mounting a smaller diameter roll on the upper shaft of the machine, that is, proportional to internal and external circumferences of the circle. It is even possible to avoid the vibrations by taking off the key from one of the three rolls, possibly from the lower right roll.

In case of pos. 3, with very small bending radii, we suggest using an upper roll with a groove of 2-3-4 mm. larger than the thickness of the profile.

This value is inversely proportional to the bending radius.

Position 4

Bending of round sections

It is better if the machine is equipped with rolls having a groove which corresponds to the diameter of the bar to be bent; as per round tubes. (Pos. 11).

Having to bend several sizes of round sections, to save money, we may supply 2 rolls having a ‘V’ groove, as per the drawing below.

Position 5

Bending of “L” or angle section leg out

As already told, the section must be inserted between the rolls from left to right, and eventually chamfered (page 3).

The rolls must be set up as shown in fig. a. The normal closed rolls will be set on the central shaft and the opened rolls on the side shafts, taking care that the radial corner is in correspondence with the internal radius of the section.

To set up the roll in this way, read suggestions given above, under the heading “Setting up the rolls”.

For all asymmetrical sections in general, and angle sections particularly, it is indispensable to use the straighteners to correct any twist which might have happened when bending (fig. b).

Standard straighteners are used for the leg out flange position.

Left straightener must be aligned with the workpiece, or at least exert a slight pressure. The right straightener should be projecting more, that is, forcing more on the sections until the exact correction is obtained (fig. c).

If difficulty is encountered in passing the workpiece over the right straightener, keep the right straightener back, nearer to the machine and have it advanced by a wrench, when profile has reached and overcome it. Another twisting may be easily adjusted by mounting 2 larger diameter flanges on the lower rolls, to support the section sidewards. Fig. d shows the defect and its correction.

In some cases, you may note a light flattening in correspondence with the leg bent on the edge. To avoid this inconvenience, it is necessary to insert a spacer as thick as the flange, and have such a diameter to support it during bending. Fig. e shows the defect and its correction.

Position 6

Bending of “L” or angle section leg in

This is one of the most difficult bending works, and the machine must be equipped with additional straighteners, as per the figure on page 19. These straighteners are supplied on demand only.

The rolls must be settled keeping into account the advice given above, under the header “Setting up the rolls”: the spacer will be mounted on the central shaft, with extra straighteners, and it must be inserted into the groove of the female roll, as shown in fig. a.

The section must always be inserted between the rolls from left to right, and eventually chamfered (page 3).

The position of the profile, in respect of the machine, must be with a leg facing the central roll and the other facing the machine.

As bending begins, it will be noted that the profile comes out twisted (fig. b): now the “C” roll must be lowered and the “D” roll must be moved ahead until the distortion is completely corrected (figure on page 19).

After this operation, go on bending and watch that the section emerges exactly squared (fig. c).

Another twisting can sometimes be corrected by replacing standard rolls with a conical roll, avoiding the profile is shut by 90°, and a flange having a larger diameter supporting the section sidewards. Fig. d shows the defect and its correction.

In some cases, a slight flattening on the back of section may be noted, in correspondence to the leg submitted to edge bending. To avoid this inconvenience it is necessary to insert a spacer as thick as the leg, and to have such a diameter to support it during bending. Fig. e shows the defect and its correction.

Positions 7, 8 and 25

Bending of “T” section

As usual, we have to consider the rules given above under the headings “Preparation of workpiece” and “Setting up the rolls”.

Bending of this section is possible in any position:

• Leg Out, pos. 7
• Leg In, pos. 8
• Side leg, pos. 25

If a strict squareness is required between the flatwise bent leg and the bending plane, it is necessary to set up the tensioning brace rods on the shaft’s ends. They are supplied on demand.

Positions 9 and 10

Bending of “U” section — Legs out pos. 9 / Legs in pos. 10

It is necessary to equip the machine with rolls expressly manufactured taking into account the sizes of section. For desultory works, it is possible to use standard rolls.

Position 22

Bending of “U” section — Side legs

This is one of the bending positions which requires more power than the others, because resisting moment, according to this neutral axis, increases remarkably.

Standard rolls can be used, but they have to be settled so that mate rolls are against the machine as per drawing.

The basis Of “U” profile bent on edge leans on male roll.

The female roll will have the back facing the legs of profile, and it will act as a guide.

Positions 11 and 12

Bending of round tubes

For this kind of work, there are no particular difficulties. However, it will be necessary to mount rolls on the machine which have a groove corresponding to the diameter of the tube to be bent.

It is possible to execute helicoidal coils, whose pitch may be determined by moving the right straightening roll when the material comes out.

To obtain coils with straight ends it is necessary to have a hydraulic adjustment model.

Positions 15, 16 and 17

Bending of square or rectangular tubes

It is necessary to equip the machine with rolls which have a groove corresponding to the external sizes of the profile to be bent.

How you may see in the following pictures, using rolls composed by several rings, it is possible to bend different sizes of profiles, saving on charges.

View ring rolls, angle rolls, profile rolls, tube rolls or Consigue una cotización