How to use a hydraulic press brake properly?

Hydraulic press brake is an important piece of metal sheet processing equipment. It can bend various metal sheets with high-precision operation. It can not only process workpieces with complex shapes to meet a variety of design needs, but also ensure mass production, accuracy and consistency of workpieces. At the same time, it also improves work efficiency, saves working time and production costs.

So how to use this efficient machine? This article will explain to you the working principle of the hydraulic bending machine and teach you how to use the hydraulic bending machine correctly.

Working principle of hydraulic press brake

Understanding the working principle of a hydraulic press brake is fundamental to its proper use. At its core, a hydraulic press brake utilizes the synchronized movement of hydraulic cylinders to drive the ram, which performs the crucial task of bending and shaping sheet metal. The hydraulic cylinders, situated on each side of the uprights, are connected to the ram through piston rods. This connection allows for the controlled up and down movement of the ram, enabling precise metal bending.

Hydraulic Press Brake

Utilizing the correct press brake setup

In press brake operations, the setup phase is pivotal, influencing costs and production efficiency. Swift and accurate setups, especially on older machines, are key to reducing costs and optimizing output. Operators must prioritize learning efficient setup techniques, emphasizing both speed and precision.

This part mainly includes the following 10 steps:

Step1: Review the Drawing

Thoroughly understand part specifications, ensuring knowledge of material type, flange dimensions, angles, and more, crucial for precision in hydraulic press brake operations.

Step2: Select the Tooling

Align tooling choice with the drawing requirements, considering air bending, bottom bending, coining, or special applications, tailored to the nuances of hydraulic press brake technology.

Step3: Determine Tonnage

Estimate tonnage using available charts, ensuring accuracy to avoid part inaccuracies and damage to the hydraulic press brake system.

Step4: Select the Hydraulic Press Brake

Choose the most suitable hydraulic press brake based on the job at hand, considering tons-per-inch limits for optimal performance unique to hydraulic systems.

Step5: Determine Tooling Position

Optimize tonnage by determining whether off-center loading is viable, adhering to machine builder guidelines, particularly critical for hydraulic press brake setups.

Step6: Install the Tooling

Align upper and lower tooling accurately, a time-consuming but critical step in the hydraulic press brake setup process.

Step7: Program the Hydraulic Press Brake

Whether manual or CNC, program the hydraulic press brake accurately for the desired bend, ensuring proper training for operators in hydraulic system nuances.

Step8: Make a Test Bend

Validate the setup by conducting a test bend on a scrap part before using production blanks, a crucial step in hydraulic press brake operations.

Step9: Correct the Program

Adjust the program during the testing phase, avoiding changes after forming an acceptable part with the hydraulic press brake system.

Step10: Run Parts

Once setup is perfected, proceed to run production parts using the hydraulic press brake, adhering to testing review procedures established by supervisors for hydraulic systems.

Basic operation methods

1. Power On and Oil Pump Start

Start by turning on the power and key switch on the control panel. Commence the oil pump, listening for the distinctive sound of rotation. It’s important to note that the machine is not yet in motion.

2. Stroke Adjustment

Prioritize stroke adjustment, a critical step to prevent damage during operation. The stroke is the distance the ram travels during its movement, and proper adjustment is crucial to ensure accurate and precise bending of the metal workpiece. Before using the machine, conduct a test run, adjusting the stroke through quick electrical adjustments and manual fine-tuning.

3. Correct selection of bending molds

Bending molds include molds and punches of normal shapes and sizes, which are suitable for most standard bending tasks. These are the basis of bending work, and various types should be fully prepared to adapt to various bending requirements.

Bending Workpieces bending tools-3

Machining Special Molds for Complex Works Special Molds: Special molds are considered very important when bending sheets of special shapes and sizes. These molds are designed for complex or non-standard bending tasks and help complete special design requirements.

Punch and die

4. Correctly Configured Backgauge

Manual front positioning is generally used for lower precision front positioning bending. Manual front positioning is an economical and practical choice for small-scale or customized work. It allows the operator to manually adjust the position of the sheet to accommodate bending jobs that do not require high precision.

Backgauge

CNC backgauge: To ensure the precision of the CNC backgauge system, the CNC backgauge system controls the position of the plate through computer or CNC system programming to achieve high precision and high repeatability of single and multi-axis, which requires large-scale and high-speed Ideal for precision tasks.

Correctly Configured Backgauge

5. Notch Selection

Notch refers to a cut or groove made in the edge or surface of a material, often to aid in bending or to accommodate other components. The general rule of thumb is to choose a notch width that is around eight times the material thickness for air bending. For example, if the plate width is 4mm, select a 32mm notch.

It can provide enough clearance for the material during the bending process. The material needs space to flow and avoid contact with the tooling, preventing damage and ensuring a clean and accurate bend.

6. Set Up the Lower Compensation System

The lower compensation system can ensure the consistent angle and curvature of the bent workpiece; the manual adjustment system allows the operator to compensate for the bending of the machine tool bottom mold through manual adjustment, which is suitable for working environments where bending specifications are not frequently changed. 

Set Up the Lower Compensation System

The automatic compensation system can be automatically controlled by the CNC system and adjust the displacement required for deflection compensation to compensate for the angle and curvature of the workpiece caused by the deformation of the machine bed, thereby ensuring consistent accuracy for each bend.

Set Up the Lower Compensation System

7. Choose the Fixture Correctly

The quick-change clamping system can greatly shorten the mold replacement time and improve production efficiency. It is especially suitable for production lines that require frequent mold replacement.

Choose the Fixture Correctly

The hydraulic clamping system provides a more stable and safer mold clamping method. It ensures that the mold is firmly fixed during the bending process, thereby reducing the risk of accidents that may occur due to mold movement.

Choose the Fixture Correctly

8. Bending

Initiate the bending process by stepping on the foot switch at the back of the machine. This sets the hydraulic press brake into motion, with the synchronized movement of the hydraulic system and the CNC-controlled slider guiding the bending operation. 

Operators have the flexibility to step on the pedal to initiate bending and release it when the desired bend is reached. This control mechanism allows for better adaptability to the specific requirements of each bending task and facilitates a safer working environment.

After starting the bending machine, try bending a single workpiece and measure the angle and position determination data. If there are no problems in all aspects of the workpiece, batch bending will be carried out.

Rules for safety operation

  1. Wear Protective Gear: Ensure proper safety attire.
  2. Pre-Startup Inspection: Check motor, switch, wires, and buttons.
  3. Positioning Device Check: Verify contact ratio, solidity, and alignment.
  4. Return to Initial State: Revert to the original procedure if the upper slide plate and positioning axes are not in their initial states.
  5. Non-Loading Start: Allow 1-2 minutes without loading after startup.
  6. Coordination and Command: When multiple people operate, the main operator must be identified and the main operator shall control the use of the foot switch. Other personnel are not allowed to use it.
  7. Bend Sheet Safety: When bending sheets, ensure proper compaction to prevent the plate from perking and causing harm to the worker.
  8. Power Cutoff for Adjustments: Cut off power when adjusting the sheet die.
  9. Material Change Caution: Avoid contact with the lower die when changing the open slot.
  10. Prohibited Areas During Operation: Never stand behind the working machine.
  11. One-Side Bending Prohibition: Strictly avoid bending on one side.
  12. Immediate Correction for Misalignment: Stop and correct if workpiece or die is not straight.
  13. Avoid Certain Materials: Refrain from bending ultra-thick/chilled steel or high alloy steel.
  14. Regular Die Check: Periodically check the contact ratio of upper and lower dies.
  15. Immediate Shutdown for Exceptions: Stop and inspect promptly in case of an exception.
  16. Protection Before Shutdown: Place a wood block on the lower die before shutdown.
  17. Proper Shutdown Sequence: Exit the control system first, then cut off power.

Maintenances of hydraulic press brake

Before initiating the machine, clear foreign matter and metal debris, and inspect the die installation, electric switch, cable, and fasteners. Prior to maintenance or cleaning procedures, lower the upper die and shut down the machine. When commencing startup or other operations, switch the upper die to manual operation status to guarantee safety.

The maintenance scope includes the following three parts:

Hydraulic oil-line

Weekly, inspect oil volume, and if it drops to the fluid window after hydraulic system maintenance, add hydraulic fluid. For new machines, replace hydraulic fluid after 2000 hours, then every 4000-6000 hours, and clean the fluid tank. Keep hydraulic fluid temperature within 35°C to 60°C.

Filter

Replace or clean the filter whenever changing hydraulic fluid. If the filter triggers an abnormal alarm or the fluid appears dirty, replace the filter. Check and clean the air filter every three months, with replacement recommended annually.

Hydraulic parts

Monthly, clean hydraulic parts (base plate, valve, motor, pump, fluid pipe) to prevent dirt entry. After one month of use, check for hydraulic tube deformation; replace if necessary. After two months, tighten all connection fittings promptly.

Mastering the proper use of a hydraulic press brake involves a comprehensive understanding of its working principles, correct setup, basic operation methods, safety rules, and diligent maintenance practices. By adhering to these guidelines, operators can harness the full potential of this powerful metal fabrication tool, ensuring precision, efficiency, and, most importantly, a safe working environment. 

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