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  • Adjustment of bending parameters of CNC press brake

Press Brake FAQs

  • How to adjust the size of the press brake?
  • How to adjust the angle of the press brake?
  • How to compensate deflection of press brake machine?
  • The press brake can’t go up and down. What’s the matter?
  • How to bend an arc with a press brake?
  • Comparison between grating ruler and magnetic grating ruler of press brake
  • Up and down moving type of press brake, which is better?
  • What is the problem that the downward speed of the hydraulic press brake suddenly slows down during operation?
  • The bending angle of the press brake is different
  • How long to change the hydraulic oil of the press brake?
  • List of hazard sources and risk assessment form of press brake
  • List of minimum bending radius of common metal materials
  • How many press brake controllers are there? How to choose?
  • How to choose between open loop and closed loop press brake?
  • What is a three cylinder press brake?
  • What is a four cylinder press brake?
  • What is the difference between three cylinder press brake and two cylinder press brake?
  • Why can’t the press brake machine return?
  • What are the functions of three motors of ordinary press brake machine?
  • What are the functions of the three relief valves on the press brake?
  • What if the press brake doesn’t go up when it comes down?
  • The press brake is normal up and down, but it is not pressurized!
  • Where does the number of backgauge axis (X,Y,Z,R) of press brake refer to?
  • How does the X-axis of press brake return to the origin?
  • Why the Y-axis of press brake does not return?
  • How many times to bend a large arc and how to calculate the bending angle?
  • How to adjust the stroke of the press brake?
  • The pressure at both ends of the hydraulic press brake is not the same. How to adjust it?
  • The cylinder stroke on both sides of the press brake is different. How to adjust it?
  • How to program CNC press brake?
  • How to adjust the downward speed of the press brake?
  • How to calculate the size and angle of sheet metal bending?
  • How to calculate the nominal pressure required by the press brake according to the thickness and length of the steel plate to be bent?
  • How to calculate the unfolded dimension of sheet metal bending?
  • How is the bending coefficient of sheet metal calculated
  • What is the relationship between bending factor and plate thickness, bending angle and bending radius?
  • How to calculate the bending coefficient of sheet stainless steel?
  • How to calculate the tolerance of sheet bending machine?
  • What is the reason why the middle of the folded workpiece is bent?
  • Why can’t the hydraulic press brake go up and down?
  • How can the angle of the press brake be adjusted if it cannot be pressed at right angles
  • How to fold different angles with a press brake?
  • How to disassemble the oil cylinder of the press brake?
  • The press brake cannot be started
  • How to eliminate the bending indentation of stainless steel press brake die
  • How to adjust the downward speed of the press brake machine?
  • What’s wrong with the unstable pressure of the press brake?
  • Why can’t the press brake machine rise?
  • What about the deformation of the press brake ram?
  • How does press brake bend a cone?
  • How to use press brake to fold a large circular arc?
  • What’s the matter with the slow down speed of the press brake?
  • What if the downward speed of the press brake is fast?
  • The downward speed of the hydraulic press brake becomes slow and the upward jitter!
  • What happened to the hydraulic oil leakage on one side of the press brake?
  • The two cylinders of the press brake are not synchronized
  • What if the workpiece interferes with the press brake machine?
  • Can the press brake machine fold the U-groove?
  • Environmental requirements of CNC press brake
  • What happened to the abnormal noise of the press brake oil pump motor?
  • A simple method for electric heating of hydraulic oil of press brake
  • What’s wrong that the press brake punch can’t lower to the bottom?
  • How to select the size of the lower V groove for sheet metal bending according to the plate thickness
  • How to break the lock of the press brake?
  • How to determine the bending radius of sheet metal?
  • How to solve the problem that the press brake pressurizes too slowly? How to pressurize quickly
  • What hydraulic oil does the press brake use?
  • How many years to change the press brake hydraulic oil?
  • What determines the sheet metal bend radius?
  • Stress relief of stainless steel 304 after bending
  • What are the corresponding protective devices of the press brake?
  • How to adjust CNC press brake?
  • What is the reason for the noise of press brake?
  • How to solve the oil leakage of oil cylinder of the press brake?
  • How to repair the scratches on mirror stainless steel?
  • How much can the bending tolerance of the press brake be controlled?
  • What is the minimum bending size of the press brake?
  • Where is the pressure relief after pressurization of the press brake adjusted?
  • How to choose electro-hydraulic servo synchronous cnc press brake?
  • How to fold a semicircle with a pres brake?
  • How is the inner radius of sheet metal bending determined?
  • How to calculate the bending radius of sheet metal?
  • How to set bending radius and bending deduction in SolidWorks?
  • The most complete sheet metal bending allowance table
  • How to set the K factor, bending deduction, bending allowance and bending calculation in SolidWorks? What’s their relationship?
  • How does the press brake accurately control the bending angle?
  • What is the reason why the blade of press brake can’t rise?
  • Which axes do the 3 + 1 axis and 4 + 1 axis of the press brake refer to respectively?
  • What does the Y value limit of press brake mean?
  • Function of time relay in press brake circuit
  • What is the difference between electro-hydraulic servo press brake and torque synchronous press brake?
  • What hydraulic pump is generally used for press brake?
  • How do you know what material the lower die of the press brake is?
  • When the press brake steps up, it cannot stop and automatically slides down
  • How to understand the N + 1 axis of press brake machine?
  • How to change the tool of press brake?
  • What material is generally used for press brake dies? What is the hardness?
  • Do you need to grind the top punch of press brake?
  • How to level the tools of press brake?
  • What is the problem that the press brake tools are not in a straight line?
  • How to repair the crack of stainless steel bending tool?
  • How to select the material of press brake die?
  • What is the problem of automatic tool drop of ordinary press brake?
  • How does the press brake go down slowly?
  • What is the difference between the acute punch and gooseneck punch of press brake?
  • The press brake tool has dents. How to repair it?
  • What is the quenching hardness of general press brake die?
  • Calculation formula of press brake die price
  • What is the general angle of the press brake dies?
  • How to select arc radius punch and die of press brake?
  • How to calculate the bending angle of the press brake?
  • What are the factors that determine the service life of press brake die?
  • How to select the top punch of the press brake?
  • Golden section size of press brake dies
  • Anti rust treatment of press brake dies
  • Comparison chart of press brake die combination
  • The press down pressure of the press brake machine is not enough, but the rising pressure is normal

Press Brake Hub

  • What is CNC press brake and it’s working principle
  • Brief introduction of synchronous system of CNC press brake
  • Workpiece bending diagram of press brake
  • Installation of CNC press brake
  • Operation of CNC press brake
  • Adjustment of bending parameters of CNC press brake
  • Bending accuracy of CNC press brake
  • Safety protection of CNC press brake
  • Press brake punch and die installation
  • Adjustment of CNC press brake
  • Hydraulic oil of CNC press brake
  • Lubrication of CNC press brake
  • Repair and maintenance of CNC press brake
  • Main structure of CNC press brake
  • Explanation of CNC press brake axis
  • Operating environment of press brake
  • Press brake punch and die selection
  • Adjustment of press brake’s mechanical part
  • Causes and solutions of common faults of press brake

Guillotine Shear Hub

  • Purpose and characteristics of the guillotine shear
  • Main structure of the guillotine shear
  • Hydraulic system of the guillotine shear
  • Lifting and installation of the guillotine shear
  • Lubrication of the guillotine shear
  • Operation and adjustment of the guillotine shear
  • Safety and maintenance of the guillotine shear
  • Guillotine Shear: Common Faults and Troubleshooting
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  • Adjustment of bending parameters of CNC press brake

Adjustment of bending parameters of CNC press brake

Table of Contents
  • Stroke adjustment
    • Top dead center adjustment
    • Variable speed point adjustment
    • Bottom dead center adjustment
  • Working pressure adjustment of hydraulic system
    • Calculation of pressure by formula method
    • Calculation of pressure by table lookup method
    • Working pressure adjustment
  • Convex amount of worktable

During the working process, the positions of the top dead center, speed change point and bottom dead center of the CNC press brake must be adjusted according to the process requirements of bending the workpiece;

Adjust the working pressure of the hydraulic system according to the actual bending force.

Stroke adjustment #

Top dead center adjustment #

The top dead center position can be adjusted by programming the “opening” item of the controller to change the upper and lower positions.

See “CNC system operation manual” for details.

Variable speed point adjustment #

The variable speed point is the position of the ram when it is switched from no-load speed to working speed. The position adjustment of the shift point can be changed by programming the “shift point” item of the controller.

Bottom dead center adjustment #

After the ram completes the working stroke, change their lower dead center position respectively through the programming of “Y-axis value” item of the controller.

Working pressure adjustment of hydraulic system #

The pressure required for bending can be calculated by table lookup method or formula method, and table lookup method is preferred.

Calculation of pressure by formula method #

The required bending pressure can be calculated from the following bending formula:

bending formula

Where:

  • F – load (KN)
  • S – plate thickness (mm)
  • L – bending length (m)
  • V – opening distance (m)
  • σ b – tensile strength (N/mm²)

The new international standard unit of force is Newton.

  • 1kgf ≈ 10N
  • 1tf ≈ 10000N=10kN
  • 1MPa ≈ 10bar

For example:

Plate material: 16Mn, σ b = 530N/mm²,  plate thickness: S = 15mm, plate length: L = 10000mm = 10m

Lower die opening distance: V = 8 × S=8 × 15 = 120mm

Calculated bending force F1 = 1.42×10000×530×15²/(1000×120) ≈ 14000 (KN)

Considering the influence of various factors, 10% reserve shall be added to calculate the bending force.

Therefore, F2=1.1 × F1 = 1.1 × 14000=15400(kN)

Calculation of pressure by table lookup method #

The bending pressure table is shown in Figure below.

Calculation of pressure by table lookup method

The value of bending force in the table is given when σ b = 450N/mm², and its unit is KN/m.

In the table,

  • S – plate thickness (mm)
  • V – opening width of lower die (mm, 8 × plate thickness)

You can use the bending pressure table to determine the required bending pressure.

For example:

It can be seen from the table that at the intersection of plate thickness S = 15mm and opening distance V = 120mm, the bending force per meter is F3 = 1200kN/m

Since σ b = 530N/mm², check table C ≈ 1.18. (530/450≈1.18)

Calculate bending force: F1=F3 × L × C=1200 × 10 × 1.18 ≈ 14000 (kN)

The required bending force shall be calculated by adding 10% reserve.

Therefore, the required bending force: F2=1.1 × F1=1.1 × 14000=15400 (kN)

Working pressure adjustment #

If the calculated bending force F2 of a bending length is less than the machine output force P in the above table, the working pressure of the hydraulic system should be reduced in order to reduce the oil temperature and improve the service life of the hydraulic components.

The working pressure Q of the hydraulic system can be calculated by the following formula:

Q=28 × F2/P(MPa)

The working pressure of the hydraulic system can be adjusted by the machine tool controller.

During adjustment, check the corresponding P value in the bending pressure table according to the actual bending force and input it into the computer.

Convex amount of worktable #

The workbench and ram are supported at two points on the whole length.

Under the action of loading force P, deformation will occur, and its deformation amount is f (see Figure below).

Convex amount of worktable

In order to solve this problem, the machine adopts the movable “convex” of the worktable to compensate the deformation of the worktable and ram and improve the accuracy of the angle and straightness of the workpiece.

The adjustable convex amount of the worktable ranges from 0 to 2.0mm.

During operation, determine the convex value according to the actual bending load force (or the angle difference between the two ends of the workpiece and the middle), and then input it into the controller for operation.

There is a small hole and a group of numbers at the end of the convex adjustment motor, which are the reference positions of the measurement hole and the convex zero point respectively, which provides convenience for users to determine the convex zero point.

Related:

  • Causes and solutions of common faults of press brake
  • Brief introduction of synchronous system of CNC press brake
  • Operation of CNC press brake
  • Repair and maintenance of CNC press brake
  • Adjustment of press brake's mechanical part
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Updated on September 23, 2022
Operation of CNC press brakeBending accuracy of CNC press brake

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Table of Contents
  • Stroke adjustment
    • Top dead center adjustment
    • Variable speed point adjustment
    • Bottom dead center adjustment
  • Working pressure adjustment of hydraulic system
    • Calculation of pressure by formula method
    • Calculation of pressure by table lookup method
    • Working pressure adjustment
  • Convex amount of worktable
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