Hybrid CNC Press Brake: Development and Applications

1. Overview:

With the increasingly fierce market competition and the rising cost of labor, the market demand for high-efficiency, energy-saving, and environmentally friendly sheet metal manufacturing equipment is becoming higher and higher. Reducing product manufacturing costs is a problem that enterprises must face. “Energy saving and emission reduction, green environmental protection” has become their preferred theme.

The power consumption of equipment has become an important part of enterprise production costs. Therefore, reducing the energy consumption of press brakes is one of the effective ways for enterprises to reduce costs and enhance their product competitiveness.

As industrial technology continues to advance, and market competition becomes increasingly fierce, the traditional hydraulic CNC press brake has increasingly prominent defects such as throttling heat generation and high reactive power consumption due to barriers in control principles.

In order to meet market needs, improve product competitiveness in the same industry, and help more sheet metal manufacturing companies transform and upgrade, our company has continuously increased its R&D efforts in the field of high-end press brakes, constantly exploring technological innovation.

In this context, the new generation of bending control technology, hybrid CNC press brake, came into being. This model is the result of many years of research and development and promotion of energy-saving and intelligent sheet metal forming machine tools.

Among them, the hybrid CNC press brake is a product that was developed earlier and has been widely used in the market.

2. Product Overview:

The hybrid CNC press brake (see Figure 1) is equipped with two independent stainless steel oil tanks, which have a simple and compact structure and are easy to clean, reducing secondary pollution to hydraulic oil.

Figure 1 – Appearance of Hybrid CNC Press Brake

In order to achieve high-efficiency and smooth bending efficiency, the main cylinder adopts a special speed-increasing cylinder structure design.

The CNC system drives the oil cylinder through two servo power units and controls the synchronous operation of the press brake oil cylinder by detecting and feeding back through a grating ruler (or magnetic ruler), realizing high-precision processing of workpieces.

This model has the characteristics of high speed, energy saving and power saving, low noise and environmental protection.

Figure 2 – Electro-Hydraulic Synchronous CNC Press Brake
Figure 3 – Hybrid CNC Pump-Controlled Press Brake

3. Technical Innovation and Advantages

1. Control Principle and Comparison

(1) Electro-Hydraulic Synchronous CNC (Valve-Controlled) System Principle and Existing Problems

The structure of the Electro-Hydraulic Synchronous CNC Press Brake (see Figure 2) controlled by a common three-phase asynchronous motor controlling a quantitative hydraulic pump, and changing the flow rate through the proportional pressure valve by restricting the overflow valve to achieve the accuracy requirements of synchronous double-cylinder bending processing is known as “valve-controlled.”

This technology has the disadvantages of energy loss and high heat generation. Energy loss in the hydraulic system reduces the overall efficiency of the system, increases oil temperature, changes the quality of the oil, and may cause the press brake to malfunction.

In order to maintain thermal equilibrium in the oil, it is usually necessary to increase the amount of hydraulic oil.

However, this method results in increased costs for waste oil treatment, as well as possible pollution effects on the environment.

In addition, the Electro-Hydraulic Synchronous CNC Press Brake produces a considerable amount of noise which can cause noise pollution in the surrounding environment.

(2) Hybrid CNC (Pump-Controlled) System Principle

The Hybrid CNC (Pump-Controlled) Press Brake (see Figure 3) consists of a power unit and a control valve group connected to the numerical control system.

The power unit includes a servo motor, a unidirectional quantitative pump connected to the servo motor, and an independent oil tank. The control valve group includes an overflow valve, a relief valve, a check valve, a directional valve, a back pressure valve, a lift valve, a safety valve, and a filling valve.

By controlling the speed of the servo motor in the power unit through the numerical control system, the displacement speed of the executing element (oil cylinder) can be controlled by adjusting the displacement of the oil pump.

By setting the torque of the servo motor through the numerical control system, the output force of the left and right executing elements (oil cylinders) can be controlled.

The displacement sensor (grating ruler or magnetic ruler) reads the displacement of the left and right executing elements (oil cylinders), and feeds back this information to the numerical control system.

After comparison by the numerical control system, the left and right power units are controlled to achieve closed-loop control of synchronous and positioning of the left and right executing elements (oil cylinders).

The displacement sensor constitutes an internal feedback loop to improve the control accuracy of the system.

(3) Comparison of Electro-Hydraulic Synchronous CNC (Valve-Controlled) and Hybrid CNC (Pump-Controlled):

High Efficiency: When running at 90% load for 2 hours, the efficiency of the machine is improved by 6%-10%.

Energy Saving: When running at 90% load for 2 hours, energy savings can be increased by 43%~50%.

Low Noise: When running at 90% load for 2 hours, the noise level is reduced by 10~13db, which greatly optimizes the working environment.

Environmental Protection: When running at 90% load for 2 hours, hydraulic oil consumption can be reduced by 50% to 75%.

Temperature Control: When running at 90% load for 2 hours, the temperature of the oil is well controlled, which is beneficial to the operation of the whole machine.

Simple and Elegant Installation: There is no external pipeline required for installation.

Through the comparison of these two control methods, we can clearly see that the Hybrid CNC (Pump-Controlled) system has the characteristics of high efficiency, energy saving, low noise, and environmental protection.

2. Unique Acceleration Cylinder Structure

The most unique technology of Ruite Machine Tool’s Hybrid CNC Press Brake is the use of an acceleration cylinder specifically designed for sheet metal press brakes with independent patented technology (patent number: ZL201721644984.2).

Traditional electro-hydraulic synchronous CNC press brakes mainly rely on the weight of the slider itself to achieve fast downward movement, as the main hydraulic cylinder is a single-acting piston cylinder. This design makes it difficult to achieve higher operating speeds.

However, by changing the internal design structure of the single-acting piston cylinder and transforming it into an acceleration cylinder, the speed of the oil cylinder can be greatly increased without being restricted by the weight of the slider. This greatly improves the efficiency of the bending process.

The Hybrid CNC Press Brake has better synchronization, true energy efficiency, simple structure, and faster speed. The use of a unidirectional quantitative pump and an acceleration cylinder are the two key elements that make up the biggest characteristic of the Dual-Servo Hybrid (Pump-Controlled) System of Ruite Machine Tool.

Compared with a bidirectional quantitative pump, a unidirectional quantitative pump has better economic performance, while the acceleration cylinder shows its stable and efficient characteristics.

4. Industry Applications and Promotion

With the accumulation of more and more application experiences, technological improvements, and optimizations, Hybrid CNC Press Brake has been widely used in sheet metal manufacturing enterprises, mainly serving industries such as shipbuilding, rail transportation, electrical switch cabinets, building decoration, 5G communications, etc.

The Hybrid CNC Press Brake is an energy-saving and environmentally friendly product, and its technical superiority has been fully demonstrated in practical production applications.

It not only responds to the call of the country to build a green social environment that is energy-saving and environmentally friendly but also meets the increasingly high-precision and high-efficiency production needs of enterprises.

It has been highly praised by users and has the trend of partially replacing traditional CNC press brakes in the future market, with very broad prospects.

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