Have you ever considered the game-changing potential of servo press technology in manufacturing? In this article, we’ll explore how these advanced machines are revolutionizing the industry, offering unparalleled precision, efficiency, and versatility. Our expert insights will reveal the key advantages of servo presses and how they can transform your production process. Get ready to discover the future of metal forming and take your manufacturing to the next level.
The stamping industry has witnessed a revolutionary advancement with the introduction of servo-driven presses, addressing the inherent limitations of conventional mechanical presses. This innovation leverages high-precision servo motors as direct power sources, resulting in unparalleled control over slider motion and overall press operation.
Servo presses offer a multitude of advantages, including:
These features position servo presses as the third-generation stamping technology and the current benchmark in the industry’s evolution.
The programmable nature of servo motors enables advanced motion control capabilities, allowing for:
This level of control makes servo presses ideal for a wide range of applications, including:
The integration of AC servo motor drive technology represents a significant focus in advanced forging equipment research and development. This technology is rapidly becoming the new standard for high-performance presses globally, offering:
As industries such as aerospace, automotive, high-speed rail, marine engineering, nuclear power, renewable energy, and defense sectors demand increasingly complex and high-performance components, the need for advanced stamping equipment continues to grow. Traditional mechanical presses, with their fixed stroke lengths, limited pressure control, and inflexible slider motion characteristics, struggle to meet these evolving requirements.
Servo presses effectively address these challenges by offering:
A servo press is an advanced stamping machine that utilizes servo motor technology to achieve precise control over the pressing operation. At its core, a servo press incorporates a feedback control system that accurately regulates mechanical displacement and acceleration throughout the stamping process.
The key components of a servo press include:
The servo system allows for unprecedented control over the press’s performance parameters:
This level of control offers several advantages over conventional mechanical or hydraulic presses:
Servo presses represent a significant advancement in metal forming technology, enabling manufacturers to achieve higher precision, productivity, and process optimization in their stamping operations.
The structure of an AC servo press comprises three primary components: the main drive system, the actuator, and the auxiliary mechanism. The main drive system is responsible for transferring energy from the servo motor to the actuator, utilizing various transmission modes such as gear, belt, screw, or hydraulic systems.
The actuator, which drives the reciprocating motion of the slider to execute the forging process, typically employs either a crank slider mechanism or a crank wedge mechanism. This component is crucial for translating the rotational motion of the servo motor into the linear force required for forging operations.
To enhance reliability and expand process capabilities, the AC servo press incorporates an auxiliary mechanism. This subsystem includes components such as balance cylinders for counteracting the weight of the slide, brakes for emergency stops and holding positions, jacking devices for maintenance and die changes, and position detection devices for precise control and monitoring.
The main drive system of servo presses can be categorized into two types based on the servo motor’s driving mode: direct drive and drive with a reducer. Direct drive systems utilize low-speed, high-torque servo motors directly coupled to the actuator. This configuration offers advantages such as simplified structure, high transmission efficiency, and low noise operation. However, the limited torque output of direct drive systems typically restricts their application to small tonnage servo presses, generally under 300 tons.
In contrast, the majority of commercial servo presses employ a main drive system featuring a deceleration mechanism coupled with a force-increasing mechanism. This approach allows for the use of high-speed, low-torque servo motors to power large tonnage presses, often exceeding 1000 tons. Three primary transmission structures are prevalent in this configuration:
These structures effectively amplify the motor’s torque while reducing speed, enabling precise control over large forces. The ability to utilize high-speed servo motors with reducers not only allows for greater press capacities but also offers improved dynamic response and energy efficiency. This design philosophy represents the current trend in servo press development, as it combines the benefits of servo technology with the force requirements of industrial forging and stamping operations.
Table 1 Comparison of project parameters
| Project | Robot automatic line | Automatic line of single arm manipulator | Crossbar double arm transmission high speed line | Single slider multi station production line | |
|---|---|---|---|---|---|
| Single line automation cost | About 12 million yuan | About 20 million yuan | About 30 million yuan | About 15 million yuan | |
| Line speed / SPM | 5~10 | 6~12 | 10~15 | 12~25 | |
| Production applicability | Multi variety and small batch | Multi variety, medium batch | Multiple varieties and large quantities | Variety, mass | |
| Production flexibility | high | commonly | commonly | low | |
| Production stability | low | commonly | high | ||
| Mold change time/min | 15 | 15 | 5 | ５ | |
| Requirements for press | Operation mode | Single time | Single time | Single, continuous | continuity |
| Press spacing / M | 6.5~8 | 6~9 | 4.5~7 | ／ | |
| Slider stroke | Small | more | large | large | |
| Mold height | Small | more | large | large | |
As shown in Table 1, the beat of the cross bar double arm transmission high-speed line is between 10 to 15 strokes per minute (SPM). By using a servo press, the beat of the high-speed line can be increased to a maximum of 18 SPM.
As illustrated in Figure 1, the servo press has the ability to set different curves depending on the specific situation.
Fig. 1 Servo press can set different curves
Figure 2 displays the power flow during the acceleration and deceleration phases.
Fig. 2 Current flow direction of servo motor during operation
As depicted in Figure 3, the low drawing speed reduces the impact on the die, leading to an improvement in die life and a reduction in die cost.
Fig. 3 Schematic diagram of drawing speed
Reducing the size of equipment can decrease the investment in plant, infrastructure, and other facilities. As shown in Figure 4, using the four-sequence press as an example, a traditional mechanical press production line consists of one multi-link press and three eccentric presses, requiring a foundation length of approximately 25 meters. In comparison, a production line consisting of four servo presses would only require a foundation length of approximately 16 meters.
Fig. 4 Comparison between traditional mechanical press and servo press
The stroke length can be set to the minimum required for production, and the appropriate forming speed for the processing content can be maintained.
1) Full stroke mode → bottom dead center precision can reach ± 0.02mm.
2) Half stroke mode (pendulum mode) → bottom dead center accuracy can reach ± 0.02mm, improving SPM.
3) Reverse mode → lower dead center accuracy up to ± 001mm.
The closed-loop feedback control ensures the accuracy of the bottom dead center, reducing the formation of burrs in the product and preventing the generation of defective products.
Servo unique auto die height correction function:
The position change of the slider can be measured and corrected to ±0.01mm of the preset value through the use of a linear grating scale in each stroke, ensuring a high degree of accuracy in the bottom dead center.
Linear grating ruler position ↓
The servo bottom dead center has an automatic correction function which ensures the accuracy of the bottom dead center at ±0.01mm even after prolonged production, thereby ensuring a high yield of products.
The low noise mode, which reduces the contact speed between the slider and the sheet metal, significantly reduces noise compared to a traditional mechanical press.
Additionally, the die experiences minimal vibration, leading to an extended service life.
Users can use this feature to create a customized slider movement mode that is suitable for their processing technology, thereby improving the accuracy and stability of the products.
This leads to an extended die life and productivity, as well as quiet blanking and the ability to process a wider range of materials, including magnesium alloys.
The servo press can be used for processes such as blanking, stretching, embossing, and bending, and can provide performance curves for different materials. The ability to pause the slider while maintaining pressure improves the quality of the formed workpiece.
The traditional mechanical press’s energy-consuming components like the flywheel and clutch have been eliminated, resulting in fewer driving parts and a simplified mechanical transmission structure.
The need for lubricating oil is reduced and the stroke is controllable. The reduced motor consumption leads to a significant decrease in operating costs.
The servo punch is mainly utilized in production processes such as drawing, blanking, bending, cold forging, embossing, and die testing.
Thanks to its utilization of PLC control, digital technology, and feedback control methods, the servo punch offers advanced precision control. This includes the ability to control the position of the press slider.
The monitoring system and compensation control enable the position of the slider to be controlled with an accuracy of ±0.01mm. The motion mode can be programmed, allowing for control of the slider’s speed and trajectory.
This reduces stamping speed, noise, and vibration, improving the stamping work environment and extending the lifespan of the die.
Additionally, the output force of the slider can be controlled with a precision of ±1.6% of the maximum output force. This allows for the formation of large panels using high-strength steel and aluminum alloy plates in the automobile industry.
Difficult-to-form materials such as magnesium alloy, aluminum alloy, and titanium alloy can be made easier to form through the combination of die design and peripheral system control.
Toggle type servo structure
Crankshaft direct drive servo structure
Figure 5 depicts the Schuler double servo bottom drive multi-station press.
Fig. 5 Schuler double servo bottom drive press
The double servo bottom drive press is powered by two separate groups of servo motors, one on the left and one on the right. These motors drive the four guide columns on each side, allowing for the movement of the sliding block.
The independent transmission mechanisms on both the left and right sides enable the table to have large dimensions on both sides, making it suitable for large tables and high tonnage presses, as shown in Figure 6.
Fig. 6 Double servo multi station press
The double servo bottom drive press uses the precise control of two groups of servo motors to achieve synchronous movement of the slider on both the left and right sides.
In the event of an eccentric load on the slider, the parallelism of the slider can be adjusted through electrical control, making it more flexible and adaptable to meet user requirements.
Compared to ordinary presses, the bottom drive press has better eccentric load strength and precision curves. While still meeting accuracy requirements, it offers improved resistance to eccentric loads and a larger area for eccentric load application.
As competition in the manufacturing industry intensifies, there is a growing demand for servo presses capable of producing high-precision, high-quality products with enhanced efficiency. This demand is driven by the servo press’s unique advantages, which align closely with the future trajectory of forging machine development.
Servo presses offer a multitude of benefits, including:
The servo press’s ability to dynamically adjust stroke and forming speed allows for fine-tuned control over the forming process. This precise control ensures exceptional accuracy at the bottom dead center, significantly reducing the occurrence of product burrs. Furthermore, the reduced die vibration resulting from optimized motion profiles extends die life, lowering tooling costs and improving overall equipment effectiveness (OEE).
The innovative design of servo presses represents a paradigm shift from traditional mechanical presses. By eliminating components such as the flywheel, clutch, and brake, servo presses not only reduce machine operating costs but also minimize maintenance requirements and improve reliability. This simplification of the drive train allows for more compact designs and easier integration into smart manufacturing environments.
As Industry 4.0 and smart manufacturing initiatives gain momentum, servo presses are poised to play an increasingly critical role in key manufacturing sectors. Their adaptability and precision make them particularly valuable in industries such as:
Moreover, the data collection and analysis capabilities inherent in servo press systems align well with the trend towards predictive maintenance and real-time process optimization, further enhancing their appeal in precision manufacturing fields.
First, consider the required accuracy of the servo press.
Accuracy refers to the precision with which the press achieves specified pressure and position setpoints. It is influenced by several factors, including driver resolution, pressure transducer sensitivity, servo motor precision, and overall system response time.
As servo motor and driver control technologies have matured and become more integrated, the repeatability of servo presses has significantly improved. This has expanded their application across various industries and processes.
For applications demanding high accuracy, careful attention must be paid to the press configuration. Key components to evaluate include:
Second, consider the structural design of the servo press.
Manufacturers offer various servo press structures to suit different applications. Common configurations include:
The selection of press structure should be based on factors such as workpiece size, required access, available floor space, and process requirements.
Servo presses can perform a wide range of functions, including:
Each function may require specific structural features or capabilities. For example, a deep-draw operation might necessitate a press with a longer stroke and higher tonnage capacity compared to a simple stamping application.
When selecting a servo press, it’s crucial to analyze your specific product and process requirements. Consider factors such as:
By carefully evaluating these factors and matching them to the available servo press options, you can ensure optimal performance, efficiency, and quality in your metal forming operations.
The stamping industry stands on the cusp of a significant transformation driven by the advent of servo press technology. This innovation promises to substantially enhance the competitiveness of stamping companies and catalyze development across various sectors of the stamping industry.
While the potential of servo press technology is immense, its widespread adoption faces challenges. The technology remains capital-intensive and, in some cases, operationally unstable due to the incomplete mastery of core servo press technology by many manufacturers. This technological gap creates a barrier for smaller, low-margin stamping companies, particularly in the context of the current economic slowdown and the reduced profitability in automobile-centric manufacturing sectors.
However, as economic conditions improve, the demand for servo presses is projected to surge. Industry leaders are expected to develop cost-effective and reliable servo press solutions within the next 5-10 years, which will likely boost the overall competitiveness of the stamping industry. The integration of AC servo motors in press drives represents a paradigm shift, offering unprecedented levels of flexibility, intelligence, and operational efficiency. This technological leap aligns with the trajectory of next-generation forming equipment development.
The servo press market is poised for rapid evolution. As related technologies mature and competition with imported products intensifies, we anticipate a significant reduction in the market price of servo technology. This price adjustment, coupled with technological advancements, is expected to accelerate the adoption of servo presses across a broader spectrum of forming equipment applications.
Key factors that will influence the future landscape of servo press technology include:
As the technology matures and becomes more accessible, servo presses are set to redefine productivity, precision, and versatility in metal forming processes, ultimately reshaping the competitive landscape of the global stamping industry.
As the founder of MachineMFG, I have dedicated over a decade of my career to the metalworking industry. My extensive experience has allowed me to become an expert in the fields of sheet metal fabrication, machining, mechanical engineering, and machine tools for metals. I am constantly thinking, reading, and writing about these subjects, constantly striving to stay at the forefront of my field. Let my knowledge and expertise be an asset to your business.
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