Intelligent hydraulic presses are classified as advanced manufacturing equipment, primarily aimed at the design, manufacturing, and usage processes of hydraulic presses. They integrate advanced intelligent technologies such as information sensing, decision-making, and secure execution, forming a human-machine system that combines human expertise with intelligent machinery. This system optimizes the organization and allocation of resources like products, tools, environments, and workers, expanding, extending, and partially replacing human physical and mental labor in hydraulic forming processes.

What are the development trends and key technologies of intelligent hydraulic presses?

1.Development Trends

• Intelligence: The slider movement curve can be optimized online based on different production processes and die requirements (such as blanking, drawing, sheet extrusion, and progressive die stamping). Special working characteristic curves can be designed to handle complex and high-precision processing, achieving "free movement" of the slider.

  
  

• High Efficiency: The stroke rate of the slider can be set within a wide range, with convenient speed and stroke adjustments. The slider can work at the minimum stroke based on forming processes, and using multi-station and automatic feeding technology can significantly improve production efficiency.

  
  

• High Precision: Through servo control technology, the movement of the hydraulic press can be precisely controlled. Generally, a slider displacement detection device is installed, allowing for accurate control of the slider's position. The movement characteristics of the slider can be optimized to reduce springback during processes like drawing, bending, and stamping, thus improving the precision of the workpiece.

  
  

• Multifunctionality: For new processes such as isothermal forging and superplastic forming, an adjustable heating environment can be created using the space between the slider and the die. This allows for the integration of forging, stamping, and heat treatment processes into a single machine, ensuring product quality and multi-functional operation.

  
  

• Low Noise: The intelligent hydraulic press simplifies the transmission system, reducing noise. By setting low-noise movement curves for the slider, blanking noise can be minimized. Compared to traditional blanking processes, the new two-step blanking process can reduce noise by at least 10 dB.

  
  

• Energy Efficiency: Servo hydraulic presses adopt direct drive, greatly reducing transmission components, lubrication, and maintenance. When the slider stops, the motor also stops, significantly reducing energy consumption.

  
  

• What You See Is What You Get (WYSIWYG): Modern software technology enables process operation simulation, allowing users to plan and optimize the entire manufacturing process on a computer, making the user experience and operation more intuitive.

Compared to traditional hydraulic presses, intelligent hydraulic presses have a broader range of applications and higher product added value. They can be used in various precision forming processes such as metal sheet stamping, isothermal forging, powder compaction, rubber vulcanization, fiberboard hot pressing, straightening, press-fitting, and injection molding.

2. Key Technologies

The primary key technologies for developing intelligent hydraulic presses are as follows:

• Development of Servo Motor Direct-Drive for the Hydraulic Press Main Pump:Currently, there are many technical challenges in using high-power servo motors to directly drive hydraulic pumps. The speed adjustment range of the hydraulic pump must be very wide, and the pump should be able to operate normally even at speeds below 10 rpm. Typical hydraulic pumps have a minimum speed of 600 rpm, making it difficult to meet the requirement for a wide range of speed adjustments.

  
  

• High-Power AC Servo Motors and Drive Control Systems:At present, switched reluctance motors (SMRs) are primarily used. These motors offer advantages such as simplicity, reliability, efficient four-quadrant operation over a wide range of speeds and torques, fast response, and low cost. As the performance of drive control systems improves and prices decrease, the realization and promotion of high-power AC servo drive technology are facilitated, making it feasible to use AC servo drives in forging equipment. However, SMRs have drawbacks such as large torque fluctuations, significant vibration, non-linear characteristics of the system, high control costs, and low power density. The key focus of research is to develop high-power AC servo motor control technology and related application technologies with independent intellectual property rights.

• Dedicated Control System:Closed-loop control of the hydraulic press’s pressure and position is achieved by adjusting the servo motor’s speed. Traditional hydraulic presses control pressure and position through proportional valves and proportional servo valves. A dedicated pump control system algorithm must be developed to ensure high stability and accuracy of the hydraulic system across a pressure range of 1 to 25 MPa. Most existing hydraulic presses are controlled by PLCs, but intelligent hydraulic presses use closed-loop control for hydraulic pressure and speed, requiring complex calculations that are difficult to meet with conventional systems. Therefore, a specialized control system using an industrial PC must be developed.

   

• Energy Recovery and Management System:To minimize energy loss, the potential energy generated by the downward movement of the slider and the energy released during cylinder decompression must be recovered and reused. In terms of energy management, instantaneous power can be several times greater than average power, so in large intelligent hydraulic presses, energy allocation must be carefully managed to avoid impacting the power grid.

  
  

• Forming Process Optimization Based on Intelligent Hydraulic Presses:The forming process varies depending on the material and shape of the part. For example, in reverse extrusion forming of magnesium alloy cup-shaped parts, the slider must undergo four different speeds during one working cycle. The process control system must meet these specific action requirements. The combination of intelligent hydraulic presses with various forming process optimizations enables the understanding of the best process paths, enhancing their performance. Studying the forming mechanism of different processes and establishing optimized parameters suited to each process is crucial for improving product quality, increasing production efficiency, and reducing costs.

   

• Optimized Design of the Intelligent Hydraulic Press Frame:Compared to traditional hydraulic presses, intelligent hydraulic presses offer advantages such as energy savings, noise reduction, and multifunctionality. Therefore, more factors need to be considered in their frame design, including potential impacts of thermal processing, extreme operating conditions, working frequency, and part complexity.

  
  

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