A complete analysis of the operation and application of bending machines: a key guide to metal processing

The core working principle of the bending machine is based on the action of force, which is what we often call tonnage. Simply put, the greater the tonnage, the greater the thickness of the material it can bend, and vice versa. At the same time, the bending length is also a key factor, which determines the maximum length of the bendable metal sheet.

The bending machine is mainly composed of an upper punch and a lower punch. The upper and lower dies on the slider cooperate with each other to achieve the bending operation of the metal sheet. Dies and punches of different shapes and specifications can produce profiles of various angles and shapes.

In terms of power drive, the cylinders on the left and right columns are responsible for driving the slider to move. When working, the slider moves downward, thereby applying pressure to the metal sheet placed on the die. The stroke of the slider is controlled by the hydraulic and electrical systems to ensure the accuracy of the movement. The body of the bending machine adopts a two-vertical steel plate structure. This sturdy design, combined with the cylinder and hydraulic and electrical control systems, ensures high precision during repeated bending operations. In addition, there is a workbench at the bottom of the bending machine to carry and support the metal sheet to be processed.

In order to prevent the workbench and slider from deforming due to long-term overload, the hydraulic bending machine is also equipped with a compensation device, which can effectively compensate for the deformation of the workbench and slider during the force process, thereby ensuring the stability and accuracy of the bending operation.

At the beginning of the specific bending process, the metal plate will be placed freely on the lower die. As the upper die gradually applies pressure, the bending arm and the radius of curvature will gradually decrease, allowing the metal plate to accurately fit the V-groove of the lower die. When the stroke ends, the upper and lower dies perfectly form a V-groove, and a complete bending operation is completed.

2. Types of bending machines

In actual applications, common types of bending machines are rich and varied, mainly including mechanical bending machines, manual bending machines, hydraulic bending machines, servo electric bending machines and CNC (computer numerical control) bending machines.

With the rapid development of science and technology, modern bending machines have successfully integrated advanced computer technology and hydraulic system principles and have become high-tech machines.

With the powerful power of modern computer technology, CNC bending machines have greatly improved the accuracy and efficiency of bending operations. The CNC controller it is equipped with can easily realize complex bending operations, providing strong support for high-precision and diversified production needs.

Hydraulic bending machines have emerged in the metal processing industry with their excellent versatility and precision. Its unique hydraulic system can provide stable and controllable bending force, which not only greatly reduces the intensity of manual labor, but also ensures the stability and reliability of bending quality.

Selection of a suitable location

The installation location of the bending machine must first ensure that there is enough space so that the operator can operate and move freely and smoothly.

The area must be equipped with an appropriate power supply to ensure the normal operation of the bending machine. At the same time, a good ventilation system is also essential, which helps the equipment to dissipate heat during operation and extend the service life of the equipment.

Use a level to carefully measure the installation ground and make sure that the ground is flat. Only a flat ground can prevent unnecessary movement of the machine during operation, thereby ensuring bending accuracy and operational safety.

Preparation of lifting equipment

Since the bending machine is a large equipment with a large weight, a crane is required to complete the lifting, unloading and transportation work. When choosing a crane, make sure that its rope is strong enough and of appropriate length to ensure that each bending machine can be lifted safely and stably. During the lifting operation, firmly fix the chain to the front lifting hole of the machine and use a crane with a safety device to minimize safety risks.

Machine leveling

After placing the bending machine steadily on the horizontal ground, use a level to test the levelness at positions A1 and A2 respectively. According to the standard, a deviation of 1-2 mm is allowed per meter. If the test finds that the deviation is too large, it is necessary to adjust the horizontal bolts at the bottom of the bending machine to make it reach the specified levelness requirements. Regularly performing such level adjustments plays a vital role in ensuring the bending accuracy of the bending machine.

Electrical connection

It is recommended that the electrical connection work be performed by professional electricians. Before connecting, carefully check whether the electrical circuit of the bending machine is damaged or short-circuited. For the electrical connection of the three-phase system, be sure to ensure that the connection position is correct. When connecting the bending machine to a three-phase power supply, pay special attention to checking whether the direction of the pump rotation drive motor is correct. If the motor is rotating in the wrong direction, it is necessary to carefully change the phase of the oil inlet circuit, but strictly avoid changing the internal circuit. After completing the phase adjustment, restart the oil pump motor and check the direction of the motor again to ensure its normal operation. Before checking the direction of motor rotation, make sure that the bending machine is clean and level.

Hydraulic system installation and debugging

In the hydraulic drive system of the bending machine, the AC servo motor is responsible for driving the slider to move and accurately adjusting the hydraulic oil through the variable speed pump. The drive device is installed on the crossbeam and connected to the machine body through the guide rail to ensure the stability and accuracy of the operation. The bending machine control system can accurately adjust the position of the crossbeam by accurately controlling the drive motor, so that it can move up and down according to the set requirements.

The grating ruler installed on both sides of the bending machine can read the signal in real time and feed it back to the control system, so as to realize the accurate monitoring and control of the bending process. The control circuit, oil filling valve and servo valve in the oil cylinder are independent of each other and are uniformly managed by the DNC controller. This advanced hydraulic or electro-hydraulic servo system can not only significantly improve the bending accuracy, but also effectively reduce energy consumption and production costs.

Attach great importance to the cleaning of the hydraulic system. Keeping the oil tank and hydraulic oil clean is the key to ensure the normal operation of the hydraulic system. When replacing the hydraulic oil, you should first carefully wipe the inside of the tank with a soft towel, and then use clean gasoline to thoroughly clean the tank. After cleaning, open the valve that stores the dirty oil, drain the dirty oil completely, and wipe off the stains remaining on the surface of the tank again.

The operating temperature of the hydraulic oil of the bending machine has strict requirements, which should not be too low or too high. If the temperature is below zero or above 70 degrees, it is necessary to install an oil heater or cooler in time to control the oil temperature within a suitable range. When filling the hydraulic oil, it should be operated through the air filter. After the filling is completed, operate the bending machine to discharge the bubbles that may exist in the hydraulic circuit to ensure the stable operation of the hydraulic system.

Installation and debugging of the back gauge of the bending machine

The back gauge of the bending machine is mainly used for precise positioning of the workpiece. When positioning the workpiece, gently place the workpiece on the lower die and slowly push it into the machine. At this time, the back gauge's finger will accurately dock with the workpiece. Through the control system, the axis of the back gauge can be flexibly moved in different directions. The X axis can move forward and backward, the R axis can move up and down, and the Z axis is responsible for moving left and right. Each axis of the back gauge is driven by an independent motor to ensure the accuracy and reliability of the movement. The Z axis and R axis can also be adjusted manually, but it should be noted that this operation can only be performed from the back of the machine.

The application of linear guides and ball screws allows each axis of the back gauge to move freely and smoothly. When moving in the X axis direction, the force is limited to 150N to prevent collisions caused by excessive impact force, thereby protecting the safety of equipment and workpieces.

Equipment inspection

Visual inspection: Check the electrical system thoroughly, carefully check whether the switch can be opened and closed normally, whether the controller display is normal, whether there is any abnormality in the appearance of the motor, and whether the grounding is firm and reliable. At the same time, check whether the oil level in the oil tank is within the normal range, and whether there are any leaks or looseness in the various components of the hydraulic system. After completing the above inspections, let the machine run idly, adjust the stroke of the bending machine to the maximum limit, and closely observe whether the machine runs smoothly, whether the motor rotates smoothly, and whether there are any abnormal sounds.

Assembly and calibration of tools: Before installing the punch and die set, be sure to stop the machine to ensure safe operation. Then, carefully install the lower die and upper die. It is important to note that the upper and lower dies of the bending machine must be accurately aligned, which is the key to achieving higher bending accuracy. When aligning the upper and lower dies, drive the slider downward to slowly approach the lower die, leaving a distance equal to the thickness of the workpiece. Next, use the lower die bolt and the upper die fixture to manually fine-tune the position of the upper and lower dies to ensure that the two are fully aligned. After the alignment is completed, push the slider upward to prepare for subsequent operations.

Safety equipment inspection

Safety devices: Carefully check whether all safety devices are in normal working condition, such as whether the light curtain can sensitively detect object obstruction, and whether the emergency stop button can quickly cut off the power supply and stop the machine after being pressed.

Personal protective equipment: The operator must ensure that he wears appropriate personal protective equipment (PPE) before operation, such as protective gloves, safety glasses and steel-toed boots with anti-smashing function, etc., to effectively protect his own safety.

Operation manual review

Before operating the bending machine, the operator should carefully review the operation manual to have a deep understanding of the various functions, performance limitations and safety features of the machine. At the same time, it is necessary to be familiar with the operation methods and precautions of the specific bending machine model and its control device, so as to know them well.

Set up the machine

Select the appropriate punch and die: Accurately select the appropriate punch and die according to the required bending angle and material thickness. During the selection process, carefully check whether the die is worn or damaged. If there is a problem, it must be replaced in time. Ensure that there are no defects such as cracks and dents on the surface of the die to ensure the bending quality.

Install and calibrate the tool: Use a clamp or hydraulic clamping system to firmly fix the tool on the bending machine table. If necessary, use shims or adapters to adjust the position of the tool. After installation, align the tool with the back gauge accurately to ensure high precision of the bending operation.

Adjust the back gauge: According to the size of the workpiece, the position of the back gauge is accurately adjusted through the control system to ensure that the workpiece can be accurately positioned during the bending process.

Programming (for CNC bending machines)

Enter parameters in the control panel: Skillfully use the software interface to accurately enter key information such as bending angle, bending length and tool parameters into the CNC system.

Develop a bending plan: Use CNC software to carefully create multiple bending sequences, optimize the bending process by rationally planning the bending sequence and parameters, so as to reduce errors, improve production efficiency and bending accuracy.

Trial run: Before officially performing the bending operation, perform a trial run. Carefully observe the operating status of the machine, check whether the tool is installed correctly, ensure that the machine can work properly, and whether the various parameter settings are as expected.

Start the bending process

Material placement: Carefully place the metal sheet on the bending machine, ensuring that it is fully aligned with the back gauge and reference points to avoid bending deviations caused by improper sheet placement.

Start the bending machine: Use the foot pedal or the command button on the control panel to start the machine, slowly press the punch against the metal sheet, and start the bending operation. For hydraulic and CNC bending machines, make sure that the hydraulic system is pressurized and ready before starting.

Supervision and adjustment

Observe the bending process: During the bending process, the operator should closely observe the pressure of the punch on the metal sheet, gradually lower the slide, ensure that the punch is pressed smoothly on the metal sheet, and steadily apply pressure to achieve the desired bending angle. After the bending is completed, release the pressure and lift the slide in time. At the same time, always pay attention to whether there is any abnormal noise, vibration or deviation during the bending operation. If any problem is found, the operation should be stopped immediately and the fault should be checked.

Check the bending angle: Carefully remove the bent metal sheet and use professional measuring tools to check whether the bending angle and size meet the pre-set specifications. If there is any deviation, necessary adjustments need to be made, and it is decided whether the bending process needs to be repeated according to the situation to ensure product quality.

Post-bending inspection

Inspect the finished workpiece: Perform a comprehensive inspection on the finished workpiece after bending to check whether there are defects, such as cracks, incorrect angles, misalignment, etc. Once a problem is found, analyze the cause in time and take corresponding improvement measures.

File adjustment: Carefully record any change information during the operation, including parameter adjustment, mold replacement, etc., to provide reference for subsequent production settings, continuously improve the operation process, and reduce the probability of errors.

After completing the bending operation, when shutting down the bending machine, you should first switch to manual mode, then step on the pedal and slowly lower the slider to align the upper and lower molds accurately. Next, press the stop button to turn off the main motor. At the same time, set the switch parameter to 0 to ensure that the equipment is in a safe shutdown state. In case of emergency, you can immediately press the emergency stop button. At this time, although only the axis and pump will be turned off, it will not affect the recovery of subsequent programs. After releasing the button, you can restart the machine.

Operator protection and training

Operator safety is always the top priority when using a bending machine. Employers must provide operators with comprehensive and systematic training on machine safety protocols.

The training content includes an in-depth understanding of the dangerous points during machine operation, such as operating points, pinch points, possible entanglement risks caused by rotating parts, and possible injuries caused by flying chips and sparks.

The operator should be familiar with the various safety features of the machine and how to quickly and accurately perform emergency stop procedures in an emergency.

The importance of correct use of personal protective equipment (PPE) is emphasized, and operators are always wearing protective equipment such as safety goggles, gloves, ear protection devices and steel-toed boots during operation.

Safety features and equipment

Modern bending machines are equipped with a range of advanced safety features designed to protect the operator's safety in all aspects.

Mechanical guards can effectively prevent operators from accidentally contacting moving parts and avoid personal injury.

As a high-precision safety detection device, the light curtain can detect in real time whether the operator has entered the danger zone. If the light curtain is blocked, the machine will stop running immediately to ensure the safety of personnel.

The emergency stop button is set in an easy-to-operate position. In an emergency, the operator can quickly press the button to stop the machine in the shortest time and avoid further expansion of the accident.

The two-hand control device requires the operator to use both hands to operate at the same time, so as to ensure that the hands are away from the dangerous area and reduce the risk of operation.

Set up cognitive barriers around the bending machine, such as railings, chains or cables, and post obvious warning signs to prevent people from crossing the dangerous area without knowing it.

Daily inspection

Daily inspection of the bending machine is the basic work to ensure its normal operation. The inspection content includes checking whether the parts of the machine are loose or damaged, whether the hydraulic system has leakage, and whether there is abnormal noise during operation. Once a problem is found, it should be handled in time to avoid the problem from expanding and affecting the production progress and equipment life.

Weekly inspection

During the weekly inspection, focus on lubricating the moving parts to ensure smooth operation and reduce wear. At the same time, carefully check whether the hydraulic hoses and joints are damaged, aging, etc. If there are hidden dangers, replace them in time.

Lubrication and hydraulic system maintenance

When lubricating guides, bearings, screws, hydraulic components, etc., it is necessary to strictly follow the guidelines provided by the manufacturer, select the appropriate lubricant and lubrication method to ensure lubrication effect.

Regularly check the hydraulic system for leaks, keep the hydraulic oil level within the normal range, and replace the filter regularly at the prescribed time interval to ensure the cleanliness of the hydraulic oil and the normal operation of the system.

Electrical system maintenance

Maintenance of the electrical system is essential for the safe operation of the bending machine. Regularly check electrical components, wires and connections to ensure that they are not loose or damaged. Keep the electrical system clean and prevent dust or debris from entering to avoid electrical failures.

Once a loose connection is found, it must be tightened in time to avoid equipment failure or safety accidents due to poor electrical contact.

Maintenance plan and manufacturer's guide

In order to ensure that the bending machine always maintains optimal performance, the maintenance plan and guidelines provided by the manufacturer must be strictly followed. These guidelines contain important information such as specific maintenance items, recommended lubricant types, safety precautions, and troubleshooting tips.

When maintaining the hydraulic oil circuit, check the oil level regularly, use the type of hydraulic oil recommended by the manufacturer, and change the oil at the prescribed intervals. Every time you change the oil, be sure to clean the oil tank to ensure the cleanliness of the hydraulic system. At the same time, pay attention to keeping the hydraulic system running within the ideal operating temperature range to avoid affecting the performance of the equipment due to excessively high or low oil temperature.

Comply with standards and regulations

In the process of using the bending machine, it is necessary to ensure compliance with industry standards and regulations for safety and reliability. For example, it is necessary to strictly comply with the General Duty Clause 1910.212 of OSHA (Occupational Safety and Health Administration), which clearly requires employers to provide adequate protection for known machine hazards to ensure the life safety and health of employees.

Follow relevant industry standards, such as ANSI B11.3 Safe Approach Guide and ANSI B11.19 Design Standard, to ensure that the operation and maintenance of the bending machine meet the requirements of the specifications and improve the safety and reliability of the production process.

For operators, in-depth understanding of the working mechanism of the bending machine, strict implementation of installation and operating specifications, and emphasis on daily maintenance and safety protection can not only protect their own personal safety, but also significantly improve the service life and production efficiency of the equipment. In the current era of rapid technological changes, bending machines incorporate advanced CNC technology, hydraulic systems and intelligent control methods, which requires practitioners to continue learning, keep up with the pace of technological development, give full play to the advantages of the equipment, and meet the increasingly diverse and high-precision requirements. production needs.

Whether it is a manufacturing company committed to improving product quality or a professional focusing on technical research, the knowledge and application of bending machines should be regarded as key points. By continuously optimizing operating procedures and strengthening equipment management, we can create more high-quality products in the field of metal processing and promote the continuous progress and innovative development of the industry.