Servo press: analysis of the core equipment of intelligent precision manufacturing

1. Core definition and structural composition
The servo press is a type of pressure processing equipment that uses a servo motor as the power core and converts rotational motion into reciprocating linear motion of the executive component (slider) through a precision transmission mechanism. It can flexibly realize various processes such as pressing, stamping, forming, riveting, and straightening. Its core structure is composed of three major modules, which combines mechanical rigidity and electronic control accuracy to provide hardware support for complex process requirements.

1. Servo drive unit

As the power source, the core is an AC permanent magnet synchronous servo motor, which is matched with a high-precision ball screw or servo pump (hydraulic servo press) to achieve power transmission. The motor has a fast response speed and can adjust the speed and torque in real time through the servo drive to accurately match the pressure and flow output required by the process. Among them, the mechanical transmission type uses ball screw direct drive, which has higher positioning accuracy; the hydraulic type drives the oil pump through a servo motor, canceling the traditional overflow circuit, significantly reducing energy consumption and noise. The oil pump mostly uses an internal gear pump, and the noise is 5-10dB lower than that of traditional hydraulic machines.

2. Execution and carrying mechanism

The actuator takes the slide block as the core and ensures motion straightness through guide rail guidance. The parallelism of the slide block can be controlled at ≤0.02mm/m to avoid workpiece deformation caused by pressure bias. The load-bearing frame adopts a C-shaped or gantry structure, which is welded and annealed to eliminate stress and ensure rigidity and stability under large-tonnage pressure. Some high-end models are equipped with eight-sided slide guides and gap adjustment mechanisms to adapt to multi-specification molds and precision processing needs. They can withstand tonnage ranging from 10 to 1,000 tons to meet different industry scenarios.

3. Control system and auxiliary units

It adopts a "PLC+servo driver" fully closed-loop control architecture and a touch-screen human-machine interface (HMI) to realize parameter visualization setting and real-time monitoring. The core is equipped with a pressure sensor (accuracy ≤ ±0.5% FS) and a displacement sensor (magnetic scale/grating scale), with a sampling frequency of up to 20kHz, which feeds back data at millisecond speed and dynamically adjusts the motor action. Safety configuration includes overload protection, light barrier protection, and emergency stop button. Some models support remote control and automatic fault diagnosis. The software level can store more than 5 million press fitting curves and support process parameter programming and secondary development.

2. Working principle and core advantages

1. Working principle

After receiving the command from the control system, the motor converts the rotary motion into linear motion of the slider through the ball screw (mechanical model) or servo pump (hydraulic model). During operation, the pressure and displacement sensors collect data in real time and form a closed-loop comparison with the preset parameters. The servo driver dynamically adjusts the motor speed and torque to accurately control the slider's travel position, movement speed and output pressure. For example, in the press-fitting process, multi-section curve control of "high speed in idle stroke - low speed close to the workpiece - constant pressure in the pressing section - pressure holding delay - high speed in return stroke" can be realized, and the whole process data can be traced.

2. Core technical advantages

Compared with traditional pressure equipment, servo presses have generational advantages in terms of accuracy, energy consumption, flexibility, etc. The core highlights are as follows:

- High-precision closed-loop control: pressure repetition accuracy reaches ±0.5% FS, and displacement repetition accuracy ±0.005mm. Combined with high-frequency data sampling, it can capture tiny defects in workpiece assembly, such as bearing interference deviations, part cracks, etc. In an application at an auto parts factory, the press assembly pass rate can be increased to more than 99.9%.

- Significant energy saving and noise reduction: Electric energy is only consumed during the power stage, and the motor is at low speed or shut down during no-load and pressure maintenance. It saves 30%-70% of energy compared with traditional hydraulic presses. The operating noise is less than 70dB. The oil temperature and calorific value are only 10%-30% of traditional equipment. No additional cooling system is required.

- Flexible process adaptation: Stroke, speed, and pressure can be programmed steplessly, supporting multiple complex motion curves, adapting to diverse needs from soft material fitting to hard metal interference press fitting. When changing models, only preset parameters need to be called, greatly shortening debugging time.

- Intelligent traceability: generate and store pressure-displacement curves in real time, which can be seamlessly integrated with the MES system to realize full life cycle traceability of production batches and process data, provide data support for quality analysis and process optimization, and meet the needs of Industry 4.0.

3. Typical application scenarios

With its precise control and flexible adaptation characteristics, servo presses have deeply penetrated into the field of high value-added manufacturing and become the core equipment in segmented scenarios:

1. Automobile manufacturing industry

It is the core equipment of automobile manufacturing and is widely used in processes such as powertrain press-fitting (motor bearings, transmission gears), body structure riveting, and brake pad assembly. Domestic enterprises such as Jinan Yijiu's servo presses have been equipped with OEMs such as Tesla and BYD to achieve high-precision control of pressure ≤ 1% FS and have a service life of more than 12 million times, meeting the needs of high-tempo mass production. International brands such as Schuler of Germany have advantages in the field of large-scale body stamping lines.

2. Home appliances and electronics industry

Suitable for precision assembly of 3C electronic components (chip wire bonding, connector press-fitting), and household appliance parts forming (refrigerator compressor parts, kitchen appliance liner stamping). Its micron-level positioning accuracy can avoid damage to precision components, and its flexible curve control can adapt to the assembly needs of parts made of different materials. In an application in an electronics factory, it can reduce the component press-fitting defect rate to less than 0.03%.

3. Hardware and jewelry processing

Used for precision pressing of hardware accessories, jewelry forming, coin/medal embossing and other processes. With its controllable pressure and uniform force characteristics, complex patterns can be pressed on the metal surface. The pattern clarity and consistency far exceed that of traditional equipment. It not only supports mass production, but also can meet customized processing needs through parameter fine-tuning and reduce mold loss.

4. Precision machining

It is indispensable in scenarios such as aerospace parts alignment, precision bearing assembly, and tooling fixture positioning and press-fitting. For example, in the processing of aerospace parts, the constant pressure holding function of the servo press can achieve precise forming of complex components and meet strict tolerance requirements. Some high-end models also support multi-station collaborative operation to improve processing efficiency.

4. Technical Parameters and Key Selection Points

Servo press selection needs to focus on process requirements and intelligent adaptation. The core technical parameters and selection points are as follows: pressure control accuracy is preferred to choose models with ≤±1%FS, displacement accuracy must meet ±0.01mm and above, and the sampling frequency should not be less than 10kHz to ensure defect capture capabilities; the stroke speed can Choose a 0.1-50mm/s stepless speed-adjustable model as needed, and give priority to high-beat models (10-15 times/minute) in mass production scenarios; tonnage coverage requires a combination of workpiece material and processing technology. It is recommended to use a 50-ton or above model for metal interference pressing, and a 10-30-ton model for precision electronic assembly.

In addition, it is necessary to pay attention to software integration capabilities, and give priority to models that support OPC UA protocols and can be connected with MES systems to facilitate data traceability; select special solutions based on industry scenarios. For example, the automotive industry can choose models with preset press-fitting process libraries, and the electronics industry focuses on low-noise and non-destructive press-fitting functions; at the same time, evaluate the full life cycle costs, and give priority to models with an energy saving rate of ≥50% and maintenance-free design to reduce long-term operating costs.