What Is Press Brake: The Ultimate FAQ Guide

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What Is Press Brake?

What Is Press Brake

A press brake is a mechanical processing tool that is mainly used for sheet metal bending and forming.

The upper tool is usually named punch and the lower tool is called die.

Press brake machines utilize matching upper and lower dies to process flat sheets, usually metal sheets, into workpieces of different shapes and angles by means of different pressure generators.

During the bending process, the top die is fixed horizontally between side uprights by clamps, and the bottom die is mounted on the worktable.

The workpiece is fixed on the lower die, and then the punch is driven by the press generator to bend the sheet metal.

The molds have different shapes and the bending angles can be set in advance. Hence, different shapes and angles of metal sheets can be produced massively.

What Is NC Press Brake?

What Is NC Press Brake

NC press brake machines are early conventional bending machines.

NC press brakes use the torsion bar to connect the Y-axis on both sides of the ram (left Y1 and right Y2) and to drive hydraulic cylinders on the uprights.

Then the ram is able to move up and down synchronously to bend metal sheets.

NC press brake is very suitable for low-cost, easy-to-operate workpiece bending but not high-precision and high-volume production

Since the NC press brake is mechanically synchronized, it cannot provide real-time feedback on the bending error and automatically adjust the error.

This will lead to poor bending accuracy.

In addition, the NC press brake drives cylinders up and down through the torsion shaft, and the long-term load will lead to the deformation of the torsion shaft.

What Is CNC Press Brake?

CNC is the abbreviation for Computer Numerical Control.

CNC press brakes are essentially mechanical tools that integrate a computer numerical control system with hydraulic press brakes.

Generally speaking, CNC press brake is driven by a hydraulic or electrical system.

After equipping with the computer numerical control system, the press brake is able to effectively and precisely bend metal materials into various desired profiles.

Hydraulic press brakes occupy the vast majority of bending equipment use share. It is the most widely used bending equipment in the bending industry.

The hydraulic press brake is powered by the hydraulic system. Y1 and Y2 axis control oil cylinders directly drive the ram to do the synchronous movement.

Hydraulic press brake has a long history of utilization and mature technology development.

During the bending operation, it is stable and reliable and is very suitable for large volume, heavy tonnage workpiece processing.

The purely electric CNC press brake is driven by the electric motor and does not use hydraulic devices or oil cylinders, so there is no problem with oil leakage.

Also, the motor only starts when bending is required and automatically shuts off when not in use.

This will reduce energy consumption and bending costs.

Electric press brake can provide accurate and fast bending operations.

However, an electric press brake is more suitable for dealing with smaller tonnages.

CNC press brake can be divided into two types according to the movement of the upper tools (punch) and lower tools (die).

Down moving:

It includes a fixed worktable (bottom), which fixes the lower tools (dies) on the table.

The upper tools (punch) are subjected to a downward force, and the upper and lower dies act together on the sheet metal to complete the bending process.

Up moving:

This type of press brake has the same parts as the first type of bending machine.

However, in this type, the upper part is fixed and the bottom part is the moving counterpart.

The bending preparation time of the CNC press brake is very fast, because there is a CNC system that accurately calculates the position of the ram and back gauge.

The CNC press brake also can checks for errors during the bending process, switching between different bending modes, positioning desired bending angles and length.

Additionally, the CNC system is able to calculate the correct bending sequence, repeating the bending action several times until the sheet metals are produced into profiles.

Overall, the CNC press brake is programmable for the entire bending process and is able to provide high precision, customized bending.

What Are the Types of Press Brake?

According to the different force application methods, press brakes can be primarily divided into mechanical press drive, hydraulic press drive, and pneumatic and servo press drive.

Although different types of press brake vary in characteristics, the main difference consists in the power running the machine.

Mechanical press brake:

Mechanical press brake

The main parts of the mechanical press brakes include workbench, ram, electric motor, flywheel, clutch and brakes.

The flywheel is driven by the electric motor.

Furthermore, the flywheel is connected to the gear shaft through the clutch and then to keep the motion of the ram.

The brakes stop the movement of the gear shaft as soon as the drive shaft is disconnected from the flywheel.

Mechanical press brakes are relatively simple in components, so they are relatively easy to handle in maintenance and operation.

Additionally, mechanical press brake is able to deal with large tonnages, even two to three times higher than the rated value.

While mechanical press brakes are not very accurate. Because when the bending operation starts, the ram needs to complete the entire cycle.

The speed of the ram cannot be controlled either. This can be dangerous for the operator and may affect bending accuracy and waste workpieces.

Hydraulic press brake:

The hydraulic press brake drives the ram movement by two synchronized hydraulic oil cylinders.

Because of the high precision and safety of the hydraulic press brakes, they have a long history and are widely used in industrial production.

The safety device of the hydraulic press brake - light curtain makes the movement of the ram can be stopped at any time, and also can reverse the operation stroke and control the speed.

Hydraulic press brakes with CNC system can intelligently handle the bending of different materials, including thickness, length, tonnage, angle, etc.

Hydraulic press brakes are also divided into torsion shaft press brake, mechanical hydraulic press brake and electro-hydraulic press brake.

The disadvantage of the hydraulic press brake is that the bending cannot exceed the tonnage range of the rated value.

Pneumatic press brake:

Pneumatic press brake

The power source of the pneumatic press brake is mainly compressed air or gas. The air pressure generated by the gas is used to apply tonnage to the ram for bending.

The machine delivers compressed air to the cylinder or pipe connected to the pressure mechanism. When filled with gas, the pressure drives the tooling downward.

When the movement is over, the gas is discharged through the exhaust valve and the brakes return to the initial position.

The power provided by pneumatic press brake cannot be compared with hydraulic press brake.

But the pneumatic press brake is very fast and clean during operation.

Servo press brake:

The power of the servo press brake mainly comes from two synchronous servo motors.

The servo motors provide energy through belts and pulleys. The flexibility of the servo press brake is very high.

The stroke and speed of the ram are accurately controlled by the servo motors. Usually, the servo press brake is suitable for bending a small amount of customized workpieces.

Additionally, the tonnages that the servo press brake can carry are also relatively small.

However, the running sound of the servo press brake is very low and will not produce noise during operation.

When the bending starts, the servo motors come into running, otherwise, the servo motors will be closed. This may save power energy and reduce production costs.

Moreover, the servo press brake is not equipped with oil cylinders, so the problems of oil leakage and cleaning do not need to be considered.

What Is Finger Press Brake?

Finger Press Brake

The finger press brake is also called box and pan brake. It is usually used to bend specially shaped workpieces or workpieces that are already semi-finished.

As you can see from the name, box and pan brakes are used to make pans, boxes and other items.

Finger press brake mainly contains clamping with many parts (fingers) of different sizes.

If different shapes of workpieces need to be manufactured, it is only necessary to remove or replace these fingers according to the bending needs.

Be sure to check that the parts on the clamping are held in place by screws before performing the bending.

When bending a piece of sheet metal, bending of different widths and shapes can be achieved by simply adjusting the size of the top die.

After bending, the formed parts also need to hold in place with screws, rivets or welding. After long-term use, finger press brake is easy to wear.

Regularly lubrication and maintenance are necessary.

What Is Horizontal Press Brakes?

Horizontal Press Brakes

The horizontal press brake is suitable for high-precision bending, straightening, punching and shearing.

It can not only bend, fold, punch and notch sheet metal, bar and tube, but also can straighten defective profiles, shear and pierce metal plates and pipes.

Additionally, completely enclosed parts can be produced by using press brake.

Horizontal press brakes are able to bend tubes into different angles and shapes. Those parts and pieces can be used to manufacture furniture, cars, metal containers, railings and so on.

The horizontal press brake can cut sheet metal even faster than the shearing machine.

Horizontal press brake can also punch and drill holes for pipes, metal plates or profiles.

Shearing, widening and narrowing the ends of pipes, then connecting different size tubes, and using them for the production of furniture, water supply system, cars and so on.

A horizontal press brake has a wide range of functions and can perform various types of bending.

Accordingly, there are many kinds of tooling matching the special functions of the horizontal press brake.

How Does Press Brake Work?

How Does Press Brake Work

The basic working principle of the press brake is to drive the ram to move through a different mechanism of power devices.

Under the preset bending angle, the upper tooling and the lower tooling are able to bend the sheet metal into different profiles.

Basically, the main parts of the press brake are: workbench, ram, the top die is called punch, the bottom tool is called die

Driving mechanism: flywheel or electric motor, clutch and brakes.

The sources of force driving the ram’s motion are mechanical, hydraulic, pneumatic press and servo motor. No matter what the power system of the brake is, the basic principle of bending is the same.

Only the force is different, that is, the tonnage is different.

The larger the tonnage, the thicker the bendable material.

The bending operator needs to place the sheet metal on the bottom die and initiate the bending program for bending.

Take the mechanical press brake as an example.

After the ram and worktable are equipped with corresponding punches and dies, the machine can be started. The electric motor drives the rotation of the flywheel.

Then the flywheel is connected with the drive shaft through the clutch.

After that, the drive shaft connects the rotating flywheel with the ram and drives the ram to do upward and downward motions.

At that time, the workpiece is fed on the bottom die.

After the upper die and the bottom die jointly press the sheet metal, a workpiece is formed.

The hydraulic press brake mainly drives the ram to move synchronously through two oil cylinders on the side uprights.

The hydraulic press brake can stop and adjust the stroke and tonnage during the bending process.

However, different from the hydraulic press brake, the mechanical press brake must complete the whole stroke after the stroke starts.

Even the stroke can pause. but it cannot be reversed.

What Is Press Brake Punch and Die?

Press Brake Punch and Die

Press brake dies are very important for bending sheet metal.

The dies of the press brake include the upper die (punch) and the bottom die (die).

In the bending process, only the matched punches and dies work together on the metal plate can the final profile be produced.

In the bending process, extrusion and friction occur between the dies and the sheet metal. Long-term bending will cause wear to the die.

Because when the dies bend the metal plate, the huge pressure makes the temperature of the contact surface very high.

This will cause damage to the dies.

Press brake toolings can not deal with metal plates with high hardness and thickness, especially cylindrical workpieces.

What Are Press Brake Dies Made of?

Therefore, when selecting the die material of the press brake, we should pay attention to the hardness, heat resistance and wear resistance of the die material.

The hardness, thickness, length and ductility of metal plates should be considered as well.

Matching plate materials should be selected for the dies.

Generally, the bottom die is used according to the standard of 5 ~ 6T, and the length is longer than the metal plate.

When the material is harder and the thickness is larger, the dies with wider grooves shall be used.

When selecting the punches, the angle of the workpiece should be determined according to the shape of the product, so as to select the appropriate punches.

There are many kinds of materials for press brake punches and dies.

At present, steel is the preferred material for making press brake dies.

For example, carbon tool steel, low alloy tool steel, high carbon high chromium or medium chromium tool steel, medium carbon alloy steel, high-speed steel, matrix steel, cemented carbide, steel bonded cemented carbide, etc.

These high-quality steels are made by special heat treatment, with high hardness, not easy to wear and strong load capacity. But it must not exceed the limited pressure that the dies can bear during bending.

Types of Press Brake Punches and Dies:

90 degree dies, acute angle dies, beading dies, box-forming dies, channel-forming dies, corrugating dies, curling dies, four-way die blocks, gooseneck dies, hemming dies, multiple-bend dies, radius dies, rocker-type dies, rotary bending dies, seaming dies, tube, and pipe forming dies, u-bend dies, and V-dies.

What Are Press Brake Used for?

Press Brake Bending

Press brake is mainly used for the bending and forming of metal plates. In the past, workers can only bend metal plates by pounding them manually.

With the continuous development of science and technology, mechanical press brakes, hydraulic press brakes and electric press brakes have entered the market one after another.

Currently, press brakes are widely used in various fields of processing and production to improve production efficiency.

Press brakes are mainly used for metal processing and manufacturing in aerospace, automobile, marine industry, agriculture, energy, military, transportation and other fields.

Why Is It Called a Brake Press?

In Old English, "brecan", "break", "brake" and "breach" are cognate words. "break" is "breken" in Middle English, which means "destroy, break, fragment and bend".

While "brake" develops from "breken" and "break". Therefore, their meaning is also very similar.

In the middle ages, people used "brake" to represent a tool used to pound and crush grain. Later, "brake" gradually became synonymous with “machine”.

Therefore, people called the machine used for pressing as "press brake".

"Press" in Medieval English means "press, strike, hit, pound".

Later, people used "press" to represent a machine used to squeeze clothes or juice.

Therefore, "press" means a tool that can apply force to an object.

"Press brake" in modern machines means a machine that applies force to bend metal plates.

Reference:

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