I. Development Background of Hydraulic Riveting Machines
With the transformation of China's national economic development approach toward structural adjustment and optimization, a focus on environmental benefits, and the enhancement of industrial standards, the transition and accelerated development of the hydraulic riveting industry have become inevitable. By upgrading traditional riveting machines with servo technology or adopting new servo hydraulic riveting machines, supplemented by other clean production methods, the industry aims to achieve energy conservation, emission reduction, green forging, and cleaner production.
II.Development Trends of Servo Hydraulic Riveting Machines
Traditional riveting machines use hydraulic systems driven by three-phase asynchronous motors operating at constant speeds, regardless of the machine's operational state. This results in significant energy waste, especially during pressure intensification and relief cycles. Excess hydraulic oil is returned to the tank via relief valves, leading to further energy loss and increased oil temperature. Additionally, these systems often employ 1:4 intensifier cylinders to achieve high pressure. However, such cylinders are difficult to manufacture, prone to failure, and frequently lead to pressure deficiencies in user equipment, with lengthy repair cycles.
As a new type of hydraulic riveting equipment, servo riveting machines, when equipped with servo hydraulic systems, can maximize efficiency and eliminate the need for intensifier systems. Features like real-time online pressure curve output, production reports, pressure control, depth control, and excellent control and stability have made them increasingly favored and recognized by enterprises. They are ideal for precision spin riveting processes in industries such as automotive, household appliances, motors, aviation, and electronics. Replacing traditional hydraulic and pneumatic riveting machines with servo riveting machines is the future trend.
III. Working Principle of Servo Hydraulic Riveting Machines
Servo riveting machines utilize AC servo motors to drive displacement and rotation, enabling precise pressure assembly and accurate pressure-displacement control. By integrating servo and hydraulic technologies, these machines combine internal gear pumps with integrated synchronous servo motors. Based on the actual pressure and flow requirements under varying working conditions, the PLC and servo driver intelligently adjust the servo motor speed according to feedback from pressure sensors. This ensures the machine delivers the precise pressure and flow needed.
The servo system employs full closed-loop control, intelligently adjusting the motor speed according to the pressure and flow demands of the riveting process. As a result, there is no overflow loss or energy waste, leading to significant energy savings.
IV.Features of Servo Hydraulic Riveting Machines
Compared to traditional hydraulic riveting machines, servo hydraulic riveting machines offer the following innovations:
No Intensifier System
Intensifier systems, which rely on cylinders that are difficult to manufacture and prone to high failure rates, often lead to pressure deficiencies and extended maintenance periods. Direct-drive servo hydraulic riveting machines eliminate the need for intensifier cylinders. Instead, they rely on the broad speed range of synchronous servo motors, intelligently adjusting speed based on riveting pressure requirements. This improves production efficiency and reduces energy consumption.
Servo-Integrated Technology
Compared to conventional synchronous servo systems, this technology adopts an integrated design, resulting in a more compact structure. It eliminates the need for additional electrical cabinets to house drivers, saving space. The plug-and-play setup reduces complex wiring work, enhancing the user experience.
Energy-Saving System
Traditional riveting machines use three-phase asynchronous motors that drive fixed-displacement pumps at constant speeds. In contrast, direct-drive servo hydraulic systems combine internal gear pumps with integrated synchronous servo motors and employ dual closed-loop control. They supply only the required amount of hydraulic oil, eliminating overflow loss and energy waste, thus achieving significant energy savings.
Digital Control System for Riveting Tonnage
The system includes a newly added Human-Machine Interface (HMI) for setting and displaying parameters. Through data communication between the HMI and PLC, the same riveting machine can handle different rivet types, truly enabling multipurpose functionality. Additionally, it allows real-time monitoring of equipment faults and PLC input/output point information, facilitating maintenance.
Low Noise and Low Oil Temperature
Conventional asynchronous motors generate continuous high noise. In servo hydraulic systems, noise varies with motor speed. The cooling fan's start-stop function can be automatically controlled, remaining off during low-load operation to further reduce noise. Since servo hydraulic riveting machines do not require high-pressure overflow and the oil pump remains at zero speed during idle periods, oil temperatures are significantly lower compared to traditional riveting machines.
