Pre-bending and bending process

Bending process of three-roll section bender

Three different types of machines

Pyramidal machines

bending process of pyramidal profile bending machines

Its upper roller can move vertically up and down to pressurize the lower roller, so it cannot be pre-bent.

3-roll profile bending machine
3-roll Pyramidal profile bending machine

Single pinch machines

Single pinch profile bending machine requires inserting the profile metal twice to pre-bending both ends.

bending process of single pinch profile bending machines
bending process of single pinch profile bending machines

single pinch profile bending machines are generally only suitable for light-capacity applications. They work by pinching the profile between two vertically opposed rolls while the third bending roll moves upward to contact then bend the profile. These tend to be older machines which in most applications require removal and reinsertion of the profile to prebend both ends so although cost-effective they are more labor-intensive in a production setting than their modern counterparts.

Double-pinch machines

When 3-roll profile bending machines are double-pinch machines, its three rollers are all drive rollers, available in light to very heavy capacities and do not require the operator to remove, flip, and then try to square the profile a second time after pre-bending. Profiles can be bent to the required diameter immediately following pre-bending because the material can be kept in the machine.

bending process of 3-roll section bending machine
bending process of double-pinch profile bending machine

Side rolls positioned to the right and left of the top roll and are on the same axis. The axis of each roll helps make the bend. The back-side roll also functions as a back-gauge to square the profile for proper alignment which eliminates the need for someone to assist the operator.

3-roll profile bending machine
3-roll profile bending machine

All BIT series profile bending machines adopt double-pinch bending

Bending process of four-roll section bender

Four-roller profile bending machines have a top roll, the pinching roll, and two side rolls. These plate rolling machines produce the fastest and most accurate bends.

bending process of four-roll section bending machine
bending process of four-roll section bending machine

The flat metal profile is placed in the machine on either side and “pre-bent” on the same side. The side rolls do the work of bending. The pinching roll holds the profile.

Profile held securely in place between the top and bottom rolls, while the side rolls move vertically to create the bend. Bottom roll moves up to hold the profile surface securely against the top roll while the side roll is raised to form an accurate pre-bend, minimizing the flat zone on the profile edge.
Plate feeding can take place on either side of a four-roll profile bending machine.

4-roll profile bending machine
4-roll profile bending machine

Side rolls positioned to the right and left of the bottom roll and on their own axes. The independent axis of each roll helps make a perfect bend. The back-side roll (at the far side of the feeding point) also functions as a back-gauge to square the profile for proper alignment which eliminates the need for someone to assist the operator.

Profile is kept square without slipping during both pre-bending and rolling because of the constant secure clamping of top and bottom rolls.

Four-roll machines do not require the operator to remove, flip, and then try to square the plate a second time after pre-bending.A profilecan be rolled to the required diameter immediately following pre-bending because the material can be kept in the machine.
Bending the back edge takes place after the cylinder is rolled allowing for a one-direction, single-pass operation.

Note: BIT series profile bending machine can work horizontally or vertically.

Pre-bending and bending process of BIT series profile bending machine

Preliminary bending in section bending
Preliminary bending in section bending

Prebending and bending process in 4 steps

Preliminary bending in section bending
Preliminary bending in section bending

Step 1: As shown in Figure 3-6, the right roller is in the lower limit position. The left roller is lifted and the main roller will be clamped to each other.

Pre-bending and bending process step
Pre-bending and bending process step 2

Step 2: As shown in Fig. 3-7, the right roller slowly rises, starts rolling, and performs pre-bending between the main roller and the left roller.

Pre-bending and bending process step 2
Pre-bending and bending process step 3

Step 3: As shown in Figure 3-8, the left roller is down and the right roller is raised. The material is sent to the left and the three rolls begin rolling, pre-bending between the main roll and the right roll.

Pre-bending and bending process step
Pre-bending and bending process step

Step 4: As shown in Figure 3-9, pre-bending and rolling ends.

Pre-bending and bending process of profile bending machine
Pre-bending and bending process of profile bending machine

Important link

List of our products:profile bending machine
Must know section bending information:practical guide to the section bending of various metal profiles