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  • Brief introduction of synchronous system 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
  • Accuracy check of the guillotine shear
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  • Brief introduction of synchronous system of CNC press brake

Brief introduction of synchronous system of CNC press brake

The electro-hydraulic synchronization system of the CNC press brake is composed of the following eight parts:

① Drive assembly
② Pressure control valve unit
③ Closed loop control valve unit
④ Closed loop proportional valve amplifier
⑤ Hydraulic cylinder
⑥ Position detection system
⑦ CNC system
⑧ Electrical system, etc

The position synchronization of the two piston cylinders during the stroke and the positioning of the stroke end point are realized by the electro-hydraulic synchronous servo system, which has high synchronization accuracy and repeated positioning accuracy.

See the below figure for the working principle of the press brake synchronization system.

the working principle of the press brake synchronization system

Fig. 2 Schematic diagram of synchronous control

The oil output from the drive assembly enters the hydraulic cylinders on both sides through the pressure control valve unit and the closed-loop control valve unit, drives the ram to move downward (or upward), and is detected and fed back to the CNC system and the electrical system through the position detection system at both ends of the ram, and then the CNC system gives the processing signal to the closed-loop proportional valve amplifier, and then the closed-loop control valve unit distributes the oil to the hydraulic cylinders at both ends, so as to achieve the purpose of synchronization at both ends of the ram.

It has high synchronization accuracy and repeated positioning accuracy.

For the hydraulic system principle and action sequence of hydraulic components of the CNC press brake machine, please refer to the hydraulic schematic diagram of the CNC press brake (Fig. 3) and the action sequence table attached to the upper right corner.

hydraulic schematic diagram of CNC press brake

Fig.3 Hydraulic schematic diagram of the CNC press brake

For the layout of the hydraulic components, please refer to figure 4 of the pressure control valve group of the hydraulic system and figure 5 of the closed-loop control valve group. The component serial number and code in the figure are the same as those in Figure 3.

pressure control valve group of the hydraulic system

Fig4. Pressure control valve group of the hydraulic system

closed-loop control valve group

Fig.5 closed-loop control valve group

When the machine is working, the ram needs to go through eight stages to complete one stroke:

  • 1: Fast downward;
  • 2: Slow downward;
  • 3: Press and maintain the pressure;
  • 4: Pressure relief;
  • 5: Fast upward;
  • 6: Decelerate upward;
  • 7: Slow to dead center;
  • 8: Stop at top dead center.

Phase 1

Operate the down button to power on 4Y3 and 4Y5.

When 4Y3 is powered on, port a and port t of lift valve (III-2) are connected, port P is closed, so that the upper chamber of cartridge valve (III-5) is connected with the oil tank, and open cartridge valve (III-5); When 4Y5 is powered on, ports P and B of proportional servo valve (III-1) are connected, ports A and T are connected, and the throttle port is the maximum.

At this time, due to the opening of (III-5) valve, the oil in the lower chamber of the two oil cylinders quickly returns to the oil tank through port A and T of (III-5) valve and (III-1) valve, and the oil pressure required to support the ram is lost at the same time.

Due to the self weight of the ram, the piston drops rapidly, the volume change rate of the upper chamber of the oil cylinder is greater than the flow of the oil pump, the upper chamber of the oil cylinder generates negative pressure, and the oil in the oil tank is pressed into the upper chambers of the two oil cylinders through the filling valve (IV). The ram forms a rapid downward operation under no-load.

Phase 2

When the ram moves down quickly to reach the set value, give 4Y5 a new parameter value through CNC system to reduce the throttle port of the proportional servo valve (III-1) to slow down.

Phase 3

Work advance boost: 4Y3 is powered off, 1Y2 is powered on, 4Y5 is powered on, and the proportional servo valve (III-1) is connected at ports P-B and A-T.

4Y3 loses power, the lifting valve (III-2) resets (Port P-A is connected and port T is closed), so that the valve (III-5) is also closed at the same time, the oil circuit in the lower chamber of the oil cylinder is cut off, and the pressure required to support the ram is quickly generated, so that the ram cannot fall freely;

1Y2 is powered on, the port P-A and port B-T of reversing valve (II-7) is connected. Close the control port of the charging valve, close the charging valve, and cut off the passage between the upper chamber of the oil cylinder and the oil tank.

At this time, the oil output by the oil pump enters the upper chamber of the oil cylinder through the fine oil filter (II-9) and port P-B of the proportional servo valve (III-1), and the proportional overflow valve (II-5) establishes pressure through the electromagnet 1Y1, forcing the ram to move downward against the supporting force and material pressing force of the lower chamber of the oil cylinder, and the oil in the lower chamber of the oil cylinder returns to the oil tank through port P-A of the overflow valve (II-5) and port A-T of the proportional servo valve (III-1).

In this way, the pressing and boosting process is completed.

Phase 4

When the pressing is completed, 1Y2 remains powered on, 1Y1 loses power and 4Y5 is powered on.

When 1Y1 is powered off, the system oil begins to relieve pressure, while 4Y5 is powered on, and P, A, B and T port of the proportional servo valve (III-1) are closed to achieve the force balance of the upper and lower cavities of the oil cylinder.

Phase 5

After pressure relief, 1Y2 is powered off and 1Y1 and 4Y5 are powered on.

1Y2 de energized directional valve (II-7) is reset, port P-B is connected and port A-T is connected.
Because port P-B is connected, the charging valve (IV) is opened to connect the oil return path between the upper chamber of the oil cylinder and the oil tank; 4Y5 is energized, and port P-A and port B-T of proportional servo valve (III-1) are connected.

At this time, the oil output by the oil pump flows into the lower chamber of the oil cylinder through the fine filter (II-9), port P-A of the proportional servo valve (III-1), the one-way valve (IV-11) and the valve (III-5), and the proportional overflow valve (II-5) establishes pressure through the electromagnet 1Y1 to make the ram move upward rapidly, and the hydraulic oil in the upper chamber of the oil cylinder returns to the oil tank through the charging valve (IV).

Phase 6&7

When the ram rises to a certain position, 1Y1 continues to be powered on, while changing the electrical signal of 4Y5 to change the opening of the proportional servo valve (III-1) and close it slowly, so as to slow down the rise and slow down to the top dead center.

Phase 8

When the ram reaches the top dead center, 1Y1 loses power and the ram stops running, so that the machine tool completes a full stroke.

Under the control of the synchronous servo system of a press brake machine, the ram of the CNC press brake can always be parallel to the workbench in the process of rapid approach, working stroke, end point positioning and return.

When the ram tilts under the action of various disturbances and eccentric loads, the position detection system at both ends of the ram detects and feeds back the deviation value to the computer, and adjusts the parameters such as the flow and pressure of the oil entering the oil cylinder through the proportional servo valve to keep the positions of the two pistons synchronized, so as to keep the ram parallel to the workbench.

Related:

  • Causes and solutions of common faults of press brake
  • Repair and maintenance of CNC press brake
  • Main structure of CNC press brake
  • Adjustment of press brake's mechanical part
  • Adjustment of bending parameters of CNC press brake
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Updated on December 19, 2021
What is CNC press brake and it’s working principleWorkpiece bending diagram of press brake

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