The Difference between Torsion-bar Press Brake and Electro-Hydraulic Press brake

There are many kinds of Press brakes on the market today, and the configurations and corresponding systems are also varied. Among them, the torsion-bar bending machine and the electro-hydraulic press brake are often pulled out for comparison due to their similar functions, but different parts, systems, prices, and other aspects. So how to choose a “never-backward” high-performance, cost-effective, and easy-to-use bending machine among many bending machines? Next, we will introduce to you the difference between the torsion-bar bending machine and the electro-hydraulic press brake from various angles.

Different structural principles

The design principles of the two models are different, resulting in different structures for the synchronization of the two sides of the bending slide. The torsion bar bending machine adopts the torsion bar linkage of left and right pendulums to form the synchronous mechanism of torsion bar force application to achieve the synchronization of the bending slider. Up and down to move both sides of the cylinder. Therefore, the torsion bar bending machine is a mechanical forced synchronization method, which cannot automatically check and adjust the parallelism of the slider. Electro-hydraulic bending machine is installed on the slider or bed with a scale, and the CNC bending machine system can analyze the synchronization of the two sides of the slider at any time through the information fed back by the scale. If there is an error, the CNC system will be adjusted through the proportional hydraulic servo valve to synchronize the travel of both sides of the slider. The numerical control system, hydraulic control valve group, and scale constitute the feedback closed-loop control of the electro-hydraulic bending machine.

torsion-bar for torsion-bar bending machine

Grating ruler for electro-hydraulic press brake

Workpiece precision

The parallelism of the slider determines the angle of the workpiece. The torsion axis bending machine keeps the slider mechanically synchronized with no real-time error feedback. The machine itself cannot be automatically adjusted, resulting in poor machining accuracy. In addition, its biasing capacity is poor because the torsion bar bending machine forces the synchronizing mechanism to move up and down on both side cylinders through the torsion bar. Electro-hydraulic bending machines control the synchronization of the slider by means of a proportional hydraulic valve group, with real-time feedback of the error from the scale. If an error occurs in the grating feedback, the system is adjusted through the proportional valve to keep the slider synchronized and improve the machining accuracy.

Bending process

Running Speed

There are three points in a machine’s work that determine its operating speed: (1) slider speed, (2) backstop speed, and (3) bending step. The torsion bending machine uses 6:1 or 8:1 cylinders, and the hydraulic synchronous bending machine uses 13:1 or 15:1 cylinders, which are slow and fast. Therefore, the rapid descending speed and return speed of the electro-hydraulic bending machine is much higher than that of the torsion bar bending machine When the slider of the torsion bar bending machine is descending, the speed, although it has the function of fast descending and decelerating, the speed of fast descending and return speed is only 80mm/s, and the speed conversion is not smooth. The rear block running speed is only 100mm/s. When the slider of the electro-hydraulic bending machine is descending, the speed has the function of fast descending and slow descending, and the fast descending and returning speed can be up to 200mm/s, and the speed conversion is smooth, which greatly improves production efficiency. At the same time, the rear stopper running speed of 400mm/s. (In the figure below, the left figure is the torque cylinder) Bending machine (the right figure is the electro-hydraulic bending machine cylinder)

Operating speed comparison

Mechanical Strength

Due to its own design, the torsion-bar bending machine cannot bend under eccentric load. If bending under an eccentric load for a long time, the torsion bar will deform. The hydraulic synchronous numerical control bending machine does not have such problems. The Y1 and Y2 axes on the left and right sides operate independently, so they can bend under eccentric load.

torsion-bar of torsion-bar bending machine

Schematic diagram of electro-hydraulic press brake

Practical Operation

Most of the torsion axis bending machines are not equipped with CNC systems, not to mention V-axis compensation, so when processing according to the drawings, we can only rely on the experience of the old workers who first set out to try to fold. Do not meet the standard also continue to try, this process not only produces a waste of material but also recruits operators with a small range of choices and high salaries. Of course, if necessary, you can also choose to add a manual compensation system. Electro-hydraulic bending machine is controlled by a professional CNC system with V-axis compensation, which is easy to operate and requires low experience for workers. With simulation bending function. No need to release samples, only need to correct the drawings to enter the step, direct bending.

Manual compensation system (upper right) and electric shaft compensation (lower left)


The greater the number of control axes, the less effective it is. Generally only X and Y axes are controlled. Electro-hydraulic bending machine is not controlled by the range of axes, at least 3 +1 axis, that is, the automatic programming can meet the high requirements, such as 4 +1 axis, 5 +1 axis, 6 +1 axis, 7 +1 axis, 8 +1 axis, such as multi-axis linkage processing, the workpiece first clamped in the bending machine, the automatic tool changer, the rotary spindle can be carried out in the head, rotary table and other operations, to complete the multi-processing, multi-surface composite processing, not only the high degree of finish, and the efficiency has been greatly improved. The efficiency is also greatly improved.

Multi-axis Selection Commonly Used in electro-hydraulic press brakes

Advanced Selection

The torsion axis bending machine can be equipped with some better configurations on the basis of the original machine, such as common quick clamps, manual compensation, lifting and stopping fingers, ball screw and linear guide rear stop, oil cooler, light curtain protection, and so on. An electro-hydraulic bending machine can not only be equipped with the above basic configuration but also can be equipped with a variety of advanced accessories. For example, on the basis of ordinary quick clamps with better TYOKKO type quick clamps or AMADA type quick clamps. The lifting and lowering of the gear fingers are not only possible manually but also by means of an electrically operated Z-tooth finger running on the guideway by means of an AC motor. The light curtain protection can also be replaced by more sensitive and safe laser protection. In addition, the servo pump control system can be equipped with many advantages such as energy saving, low noise, fast stamping speed, higher precision, and less fuel consumption. Manipulator that can greatly improve productivity; hydraulic clamping system; follow-up feeding and laser angle detector.

Common Selection of Torsional Shaft Bending Machine (Left) and Electro-electro-hydraulic press Brake (Right)

The main difference between an electro-hydraulic press brake and a torsion-bar bending machine lies in whether there is a feedback closed loop and whether there is compensation by an electro-hydraulic press brake. The two should be clearly distinguished. The torsional shaft bender mechanically adjusts the stroke of the oil cylinder, while the hydraulic bender controls the stroke by hydraulic pressure. The torsional bending machine is controlled by the balance shaft, while the electro-hydraulic press brake is synchronized by servo-proportional valves on both sides. electro-hydraulic press brake refers to a combination of electrical and hydraulic advantages. It has the advantages of high control precision, fast response speed, large output power, flexible signal processing, and easy realization of feedback on various parameters. The working efficiency of one electro-hydraulic press brake can be equal to that of two to three torsion-bar bending machines.

To sum up, the bending machine is selected according to the actual processing requirements. The hydraulic servo synchronous bending machine has high precision, real-time error feedback, and strong anti-deflection load capability of the bending slider. The torsional axis synchronous bending machine has low precision, no error feedback, and poor anti-deflection load capability of bending slide block. The hydraulic servo bending machine is more complex and more expensive than the torsional axis synchronous bending machine. According to the above introduction, you can choose the appropriate bending machine from the following specific aspects.

1. Precision requirements for processing workpieces (precision deviation of torsional axis bending machine).

2. Daily working time of the machine (electro-hydraulic press brake has high efficiency, which can shorten working hours and reduce labor costs).

3. Whether the machine operator is an old employee (the twisting axle bending machine can only be debugged through experience, and it is not easy for the novice to operate, while the electro-hydraulic press brake is controlled by the system and is simple and convenient).

4. Whether or not to purchase an over-twisted shaft bending machine before to understand the failure rate. Frequent failures will reduce work efficiency and delay the construction period (the failure rate of electro-hydraulic press brake is extremely low).

Twisted shaft bending machineelectro-hydraulic press brake
Workpiece precisionThere is no too high requirement for workpiece precision.High requirements for workpiece precision and attention to detail
YieldThe demand for workpieces is small and the requirement for work efficiency is not high.There is a large demand for workpieces, which requires high work efficiency.
Practical OperationThere are many situations requiring manual operation, which is slightly inconvenient.Intelligent numerical control, complete functions, easy to use
Applicable companyThe new company was primarily a groping attempt at the beginning.Large-scale old brands with equal emphasis on output and quality
PriceThe price is lower, some accessories need to be matched separately.The price is on the high side, but the function is complete and the quality is good. Generally speaking, the cost performance is very high.

Learn more about shearing machines, bending machines, and other sheet metal equipment. For the best price, please contact us.

Fengli Machinery Group Machine) Work) Work) (Industrial Blades)


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