Press brake is widely used in the sheet metal industry and manufacturing industry. However, every year, the use of the press brake causes an endless number of accidents.
Many employers or users do not pay attention to the safety training of the press brake. Many press brake manufacturers also lack enough safety protection devices.
The main danger of using the press brake is that the operator will bypass the safety guards and enter the bending area of the machine.
In addition, the clamp and the rapid movement of the backgauge may also cause danger to the operators.
When installing a new press brake, upgrading the machine, and renovating the machine, the risk factors of the press brake must be evaluated again.
The dwell time of mechanical and flywheel press brake is relatively long, which cannot be achieved if modern light curtain protection technology is used.
The stop time of the hydraulic press brake is shorter, and more protection measures can be adapted.
The Potential Danger of Press Brake
When using the press brake, the common injuries are crushing injury and contact with the operating point of the machine.
For example, set and adjust the machine, press brake bending, clean the machine blockage, lubricate the machine, and maintain it.
Common hazards include touching the foot switch during operation, being pressed during bending, and hurting caused by failing to close the relevant parts.
It may also be pinched by the backgauge and may be injured when changing the punch and die.
Basic Protection Operation
First of all, employees need to receive relevant training before taking up their posts to operate the bending machine.
Train operators on safe operation procedures, equipment knowledge, and functions of protective devices of the press brake.
How to identify hazards and emergency control the machine. Strictly supervise the employees to follow the operation rules.
Before bending operation, it is necessary to wear personal protective equipment, such as gloves and goggles.
The surrounding of the machine shall be kept clean and will not affect the operation of the bending machine.
The machine should be commissioned to prevent malfunctions and contamination. When bending, pay attention and do not leave the bending machine unattended.
Light Curtain Protection
The common protection device of the press brake is infrared light curtain protection. The light curtain is actually a product testing equipment, which was later used for machine protection.
The light curtain is a kind of photoelectric induction equipment, which is used to prevent the human body from contacting dangerous areas.
The light curtain can be installed near the toolings of the hydraulic press brake. The light curtain system is composed of a light curtain emitter and a receiver.
The light curtain system is part of the machine control circuit because it needs to be connected to the safety monitoring relay and the magneto starter.
The light curtain creates a sealed protective area near the toolings through an infrared beam.
If the operator's hand passes through the work area, the press brake will stop bending after receiving the signal, or will not continue working until the operator's hand is removed.
The light curtain can not only protect people in the working area but also protect people near the operating area.
After the LED emitter and receiver of the light curtain sense the object, the interruption of the light plane will start the output signal.
The bending will stop whether it senses the worker or other objects, or the next cycle will be carried out after removing the objects.
The installation, type and emergency braking function of the light curtain make the safe distance between the light curtain and the press brake uncertain.
When the press brake bends the workpiece, the light curtain may receive an incorrect signal.
Therefore, the light curtain also has a function of automatically closing the light curtain system just before the punch bends the workpiece.
The light curtain also has a floating blank function. The bending stroke does not need to be stopped. The light curtain system works during the whole bending stroke and the light curtain cycle.
Moreover, when the operator moves the workpiece outside, he will not put his hand into the working area of the light curtain, so the light curtain can work normally.
On both sides of the press brake, the infrared beams emitted by the light curtain system in front of the working area are synchronous and parallel.
The light curtain is divided into programmable and non-programmable. For the programmable light curtain system, the flange of the workpiece can be input into the program.
This can cancel the light beam blocked by the workpiece, and the ram can reach the up dead point without stopping.
The non-programmable light curtain cannot cancel the interference light beam, which will cause the operator to close the light curtain, thus bringing danger to the operator.
In addition, when bending very small workpieces, the operator needs to manually adjust the workpieces, so the light curtain does not work when the operator stands in front of the working area.
Two-Handed Control Device
This is an effective device to protect hands from injury. Vertical control device with two manual control buttons.
The operator must press both control buttons at the same time to start the press brake. If the button is not pressed, the machine will stop working.
After manually pressing and holding the button, it stops when the mold falls to a certain position.
Then the operator can feed the workpiece and use the foot switch instead of the manual control button to bend the workpiece.
The two-hand control device enables the operator to feed the workpiece at a distance from the operating point between the punch and the die.
This will protect the operator's hand from the hurt of the punch and die.
The function of this device is to prevent the operator's hand from approaching the operating point when the machine is bent.
The side guards are movable guards on both sides of the machine. The side guards prevent the operator from reaching into the work area or rear gauge from both sides of the machine.
This will prevent the operator's hands from being injured
The rear guard prevents access to the machine from the rear. The operator can be prevented from being collided by the rear gauge.
The shell of the press brake and the interlocking press barrier can also be set at a certain safety distance.
This can avoid damage to the press brake by personnel and objects, and also avoid injury to the operator.
There are also some factors harmful to the operator during the installation of the tools. The tools may suddenly fall and hit the operator's hand. Or the sudden movement of the machine ram.
Before installing the toolings or other tools, the ram needs to be locked at the closed height position and the ram needs to be raised to the highest position.
The installation of other tools also needs to adjust the position before turning off the corresponding switch.
The press brake needs regular maintenance and personal protective equipment should be worn during operation.
The press brake must be equipped with corresponding protective devices and some obvious warning signs.
The manufacturer of the bending machine needs to provide the bending machine operation training materials for the customer.
The employer needs to provide professional pre-job operation training for operators and formulate strict press brake operation rules for operators.
A press brake is a complex machine, and the use of the press brake requires special attention to safety issues.
What are the safety rules about press brake tonnage?
The tonnage of the press brake must be determined according to the thickness of the metal plate and the shape and size of the bending.
The tonnage can be determined by referring to the press brake tonnage table on the machine. Excessive tonnage can bring danger to the operator and damage the workpiece and machine.
When the tonnage reaches the maximum, the length of the workpiece shall not be too short, and at least one-third of the length of the workbench shall be reached.
What safety method can best protect a press brake operator？
There are many methods to protect the operator of the press brake. Different methods are used in different situations.
For modern NCN press brake, it can be equipped with light curtain protection and other induction devices.
Many old mechanical press brakes cannot use this method. In this case, pullbacks and restraints can be used. The purpose is to prevent the operator's hand from entering the operating point.
This method requires the wrist strap to be fixed on the operator's wrist. When the machine is started, the operator's remote hand is pulled away from the operating point.
After the operator replaces a new mold, it is necessary to visually check and adjust the pull-back device before bending. Then the mold will not interfere with the pull-back device.
The restraint is to prevent the operator's hand from reaching the operating point through the anchoring device and the rope wrist strap.