Metal forming refers to the process of using active power to deform metal materials and obtain the required shape parts within the limit of tooling and die.
Metal forming parts mainly include forgings, stamping parts, sheet metal parts, etc., which consume 70% of the total amount of metal materials such as sheet metal, pipe, bar, wire and profile.
There are more than 10 million employees in the whole metal forming industry, creating 2 trillion yuan of industrial added value every year, purchasing 80 billion yuan of forming technology and equipment, and consuming 100 billion yuan of tooling.
In the three metal forming industries of forging, stamping and sheet metal making, production process, technical equipment, tooling and raw materials are indispensable.
Among them, the metal forming machine based technical equipment provides forming energy, which plays a key role in ensuring product quality, improving production efficiency, reducing operators, controlling production costs, environmental protection and energy saving, sustainable development and other aspects.
In today’s era, network, information and intelligence not only change our work and life style, but also subvert the manufacturing and metal forming industry.
At present, the construction of automation, information and intelligence in metal forming enterprises is an urgent task, and the adoption of intelligent machine tools is a prerequisite for the use of automatic production, the construction of information chemical plants and the realization of intelligent manufacturing
On the contrary, without intelligent machine tools, it is difficult or impossible to realize the automation, informatization and intelligence of enterprises.
Therefore, it is a compulsory course for metal forming enterprises to adopt intelligent machine tools or carry out the intelligent transformation of machine tools.
In the intelligent metal forming machine, the intellectualization of the main drive is very important
The core to solve the intelligent main drive of metal forming machine tool is to use servo main drive.
Based on the application industry of metal forming machine tools, this paper analyzes and prospects the servo mode of the main driving mode of metal forming machine tools in forging, stamping and sheet metal manufacturing industries, so that each metal forming machine tool enterprise can plan its own development direction, help each metal forming parts manufacturing enterprise choose to purchase machine tools, improve product quality, reduce production cost and improve comprehensive competition power.
With the development of metal forming machine tools, it is imperative for forging machine tools, stamping and sheet metal making machine tools, mechanical machine tools and hydraulic machine tools to develop in the direction of servo main drive.
The advantage of using servo drive in metal forming machine has been fully proved by the production practice of various industries
The servo-driven metal forming machine is not only of good processability but also of energy saving.
It is easy to realize automation integration, information networking and intelligent control.
It is a must for future metal-forming enterprises.
Among the four kinds of forming machine tools for forging production, the forging hammer has developed from steam-driven and air-driven to the most commonly used electro-hydraulic drive.
Some machine tool enterprises have developed the mechanical servo-driven forging hammer (Fig. 1), which completely subverts the concept of traditional forging hammer using fluid medium transmission, and is a revolutionary change in the driving mode of forging hammer.
Screw press has developed from flywheel friction drive to the most commonly used frequency conversion (or permanent magnet) motor direct drive. At present, some enterprises have developed mechanical servo-electric direct drive mode (Fig. 2), with higher efficiency and better performance.
Mechanical press, commonly known as die forging press, the drive motor is also upgraded from ordinary asynchronous AC motor to servo motor drive mode (Fig. 3), eliminating the deceleration and braking structure, making the press structure simpler, easier to maintain, and even cheaper.
It is difficult to manufacture heavy forging machine tools at present because of the restriction of servo motor power.
Forging hydraulic press developed from hydraulic press to the most commonly used hydraulic press
The hydraulic press has also developed from the traditional servo valve control mode (with accumulator) to the servo pump control mode (without accumulator) (Fig. 4), which greatly improves the energy efficiency and stroke times of the hydraulic press.
In the performance comparison between the hydraulic press and mechanical press, the comprehensive competitiveness is improved.
In addition, the forging machine, roll forging machine and cross wedge rolling mill also adopt the mechanical servo direct drive mode (Fig. 5 and Fig. 6), with simple structure, easy manufacturing, low energy consumption and superior performance.
Fig. 1 Mechanical servo linear hammer
Fig. 2 Mechanical servo screw press
Fig. 3 Servo cold forging press
Fig. 4 Hydraulic servo cold forging press
Fig. 5 Servo roll forging machine
Fig. 6 Servo cross wedge mill
Among the two main types of forming machine tools in stamping production, the servo drive of the mechanical press (Fig. 7, FIG. 8, FIG. 9 and FIG. 10) will gradually replace the traditional asynchronous motor drive, thus completing a revolution in stamping machine tools and production technology.
In Europe, the United States, Japan stamping industry, mechanical servo press has been widely used
It is reported that the world’s top stamping machine companies such as Schuler and Komatsu no longer recommend the use of traditional mechanical presses for large press users;
According to the information learned by China Forging Association, the stamping workshop of the main engine plant of the joint venture of the world’s top automobile companies in China will no longer use the traditional mechanical press in the future.
The hydraulic servo direct drive technology of hydraulic press (FIG. 11) will also promote the technical reform of hydraulic press, reduce energy consumption, improve the impact times, further improve the comprehensive performance of the hydraulic press, so as to broaden the application scope of the hydraulic press.
Fine blanking press is developing from servo valve controlled hydraulic press (with accumulator and large oil tank) to servo pump controlled hydraulic press (without accumulator, only with small oil tank), and even to mechanical servo drive (currently only used for small presses below 200t).
The development ideas of hot stamping press and fine blanking press are the same, and they are also developing from valve controlled hydraulic press to pump controlled servo drive mode, and even to mechanical servo drive mode (Fig. 12 and FIG. 13).
Fig. 7 Servo single point press
Fig. 8 Servo two point press
Fig. 9 Double servo multi station press
Fig. 10 Servo press
Fig. 11 Hydraulic servo press
Fig. 12 Servo fine blanking machine
Fig. 13 Servo hot stamping press
Among the two major types of machine tools for sheet metal processing, the CNC punch has developed from the rudimentary step punch to the mechanical CNC punch, then to the hydraulic servo CNC punch, and finally to the most popular mechanical servo CNC punch (FIG. 14)
Not only more energy saving, reduce vibration and noise, but also greatly improve the adaptability of CNC punch.
It not only can be used for blanking, but also can achieve more sheet forming, improve the service life of the die, and strengthen its own process advantages compared with laser cutting.
In all kinds of metal forming machine tools, the development of numerical control punch is rapid.
In just a few decades, four generations of CNC punch have changed. What will the future CNC punch look like?
It’s worth looking forward to.
Another key machine tool for sheet metal processing, CNC press brake machine, like CNC punch press, has experienced from CNC hydraulic, CNC hydraulic servo press brake machine to today’s widely used CNC servo hybrid press brake machine in just a few decades (FIG. 15).
It is not only environment-friendly and energy-saving, but also machine tool technology is good, easy to realize automation, intelligent production.
In addition, we should pay attention to that in the small CNC press brake machine, the use of CNC mechanical servo drive (Figure 16) has become a trend.
Compared with the previous generations of press brake, in addition to the advantages of the servo hybrid press brake, the drive structure is more simple, easy to maintain, and the manufacturing cost is lower.
Fig. 14 Servo CNC punch
Fig. 15 Hybrid drive press brake machine
Fig. 16 Servo press brake machine
The two major types of metal tube and wire forming machines, tube bending machine and wire bending machine, have also developed from the early ordinary hydraulic main drive and hydraulic servo feed to the pure mechanical servo main drive and mechanical servo feed fully electric mode (FIG. 17) And Figure 18), so that the machine structure is more simple, easier to achieve automation, easy to maintain, safe and reliable operation, can achieve energy saving, green production.
Fig.17 Fully electric pipe bending machine
Fig. 18 All-electric multifunctional forming machine
All in all,
- The main drive of the metal forming machine is servo, which makes the performance of the equipment better and the technology better;
- It is more suitable for automatic production, information management and data diagnosis;
- More energy conservation, environmental protection, human green, sustainable development.
Among them, mechanical servo direct drive is the most advanced drive mode.
Restricted by the servo control system, servo motor manufacturing technology and cost, it is still very difficult for large metal forming machine to adopt mechanical servo direct drive
A set of mechanical transmission structure is still needed between the motor and the slider, but they are all mechanically rigid connected, with high energy transfer efficiency, high motion control accuracy, simple structure and easy manufacturing and maintenance.
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