Technical Observation and Thinking of Stamping and Sheet Metal Manufacturing Industry

I have successively participated in the 2018 and 2019 National Stamping and Sheet Metal Manufacturing Enterprise Directors Conference and China International Metal Forming Exhibition hosted by China Forging Association. Through participating in the conference and visiting the exhibition, I have a deeper understanding and thinking about the development status of new technologies and new equipment in the stamping and sheet metal fabrication industries. The following are some of the most impressive aspects of the conference and visit.

Servo technology is gradually popularized and applied

With the increasingly fierce competition of automobile products, the shape of stamping products is becoming more and more complex, the stamping process is diversified, the mold structure is complicated, and the materials are lightweight and diversified; Customized, refined quality requirements for various sheet metal parts and precision blanking and deep drawing parts are also getting higher and higher. The application of advanced stamping technology is inseparable from the technological progress of equipment. In recent years, servo stamping and sheet metal production equipment have begun to be widely used in response to the needs of products and processes.

In the mid-1990s, the servo press came into being and developed rapidly due to its superior performance. In China, the development of servo presses is in the ascendant, and has been widely popularized and applied in major automobile OEMs. According to incomplete statistics, there are currently more than 50 large-scale servo press production lines in the country, and there are countless applications of small and medium-sized servo presses.

Initially, people were skeptical about the advantages and energy saving aspects of servo presses, and they were not sure whether the price/performance ratio of servo presses was reasonable. After nearly 20 years of development and application of servo press technology, the advantages of servo presses have been continuously discovered and proven, and new technologies have been continuously improved and developed according to product and process requirements, and supported by some actual data. Servo press technology has been a continuing hot topic in recent years.

Functions and advantages of servo presses

The product formability is improved and the quality is improved. Servo presses combine mechanical reliability with hydraulic flexibility. According to different products and process requirements, different motion curves can be output, and the stroke and speed of the slider can be adjusted to meet different process and quality characteristic requirements, and can effectively solve the quality risk caused by material changes and greatly reduce the return loss. Stretch and die cut separate rip band.
Improve production efficiency and maximize economic benefits. In the full stroke mode: the individual programming control of the slider movement at the same or lower forming speed greatly shortens the cycle time and improves the efficiency. In swivel stroke mode: Allows free programming of the slide stroke height. Through the counter-rotation of the torque motor, the eccentric drive of the carriage moves in an oscillating manner, which can significantly increase efficiency and save energy. According to Schuler’s experience in the stamping production of servo presses, compared with ordinary presses, the production efficiency of some small and medium-sized progressive dies and multi-station dies is increased by an average of 70% by using servo presses.
Save energy. The servo press is equipped with an energy feedback management system, which can save energy by 20% to 30%.
Reduce noise and improve mold life. Due to better control of the momentary speed of contact with the mold, it can effectively reduce the impact and vibration on the mold, reduce noise, improve the life of the mold and press, and improve the harsh working environment of the stamping factory in the past.
The structure of the press is simple, the failure rate is low, and it is easier to maintain, as shown in Figure 1.
The overall height of the press is reduced, and the compact structure occupies a small area, which reduces the requirements and restrictions on the height of the stamping workshop, and reduces the investment cost of the stamping workshop.
When installing and testing the mold of ordinary presses, the “inching operation” used requires high operating skills, and the control is inaccurate, while servo presses can perform micro-operations of 0.01mm each time when adjusting the mold. Make the adjustment operation of the mold simple, convenient, fast and accurate.
The servo press can be combined with the automatic device, the control is more flexible and the efficiency is maximized. The movement of the slider is programmed and controlled by a servo motor with high dynamic performance, so that it can easily and quickly adapt to the parameters of the mold and automation process, so that the slider and the automation device can be optimally coordinated, and the efficiency can be improved while ensuring the quality. . Some servo presses are equipped with an “optimized program curve generator”, which can automatically optimize the operating parameter curve of the slider and the automation system according to the mold and parameters. At present, the highest beat of the automatic line of large servo press reaches 18 times/min.
Servo presses make stamping production easier to realize automation, informationization and intelligence.

New Technology and Application of Servo Press

Realize follow-up process integration. The production of parts often involves many processes, which require different processes to complete. Execution one by one requires additional tooling and equipment, which wastes a lot of time and reduces production efficiency. Servo presses allow free programming of stroke heights and motion sequences according to user requirements for maximum flexibility. Processes such as welding or lasers can also be used to integrate processes such as welding or lasers directly and reliably into an efficient stamping cycle, such as Weld nuts, weld bolts, thread forming, component welding, riveting, etc.
It can realize plate forging that cannot be done by traditional presses.
A new type of punching press with servo direct drive technology: a highly dynamic drive motor and one or two toggle levers. The absence of mechanical linkages, a lubrication-free and wear-free drive system greatly improves process reliability and part quality.
Schuler’s dual-servo technology (Figure 2): It is mainly used for large-table multi-station and independent presses of more than 1,000 tons. It is characterized by dual-servo motor drive, the driving device is placed below, and the slider is moved to achieve synchronization. control. Significantly improve the anti-eccentric load capacity of the press, the deflection of the press is reduced by 30%, the single-process load capacity is higher, the mold is protected, and the quality of the parts is improved; more flexibility is provided for the multi-station layout; the active slider parallel control, the pressure The overall height of the machine is lower, the sealing is better, and it meets the environmental protection requirements such as noise prevention and oil-free.

Domestic servo presses have made great progress, but the research and development of low-speed high-torque servo motors and the core technology of control systems are still in their infancy, which restricts the development of servo presses in my country. At present, there are more than 50 large-scale servo press production lines in use in China, foreign brand presses account for 90% of the share, Schuler alone accounts for 50% of all large-scale servo presses, and domestic brand presses only account for 10%. The core servo motors and control systems of these domestic servo presses all rely on imports. These core technologies are controlled by a few companies in Germany and Japan, and the prices are high. The technology development of domestic manufacturers lags behind, and they have not broken through the technical barriers of Europe, America and Japan, so they can only rely on imports. With the increasing demand for servo presses, my country urgently needs to develop core components such as high-torque servo motors and control systems.

Laser technology can do anything

Laser technology is “omnipotent” and can be called a universal “light knife”. Laser has the characteristics of high brightness, high directionality, high monochromaticity, and high coherence. Laser technology has been widely used in aerospace, rail transit, automobile manufacturing, shipbuilding, construction machinery, agricultural machinery, elevator manufacturing, kitchen appliances, Various industries such as electronics and electrical. Laser technology can complete marking, cutting, welding, cladding and quenching, surface heat treatment, 3D printing, hole making, cleaning and other processes. At present, domestic laser technology has made great progress and has broken the monopoly of foreign high-end laser equipment companies.

cutting aspect

The cutting thickness of thick plate is up to 50mm for stainless steel and 40mm for carbon steel.
The maximum positioning speed of the high-speed cutting machine can reach more than 200m/min.
The high-power cutting machine can achieve more than 15kW in China.
Ultra-large-format cutting machine, large-size parts can be cut and formed at one time. The width can reach 5m, and the length can reach 8-50m.
Fully automatic flexible processing production line (Figure 3), consisting of multiple laser cutting machines and automation systems, fully automatic loading and unloading and process transmission, the entire processing process realizes informatization and intelligent control, breaking foreign monopoly.
Automatic optical fiber three-dimensional pipe cutting machine can realize three-dimensional cutting of various sections and holes of various pipe fittings.
The uncoiling laser cutting line replaces the uncoiling blanking line, saves mold investment, is more suitable for flexible production of multiple varieties and small batches, and breaks foreign monopoly.
Robotic 3D laser cutting machine, fiber laser and industrial robot are highly integrated, flexible processing can be completed at one time. It is mainly used for the cutting of automobile panels, instead of plasma cutting, trimming dies and punching dies, which can improve the quality of parts and save mold costs.
Three-dimensional five-axis laser cutting machine for thermoformed parts – high-strength steel laser cutting and forming, breaking the foreign monopoly.
Three-dimensional five-axis laser cutting, welding and 3D printing integrated equipment, multiple functions, realized by one machine.

Welding

The laser-arc hybrid welding system combines the advantages of laser welding and arc welding, and is suitable for welding difficult-to-weld materials and thick metal plates, and is suitable for welding processing of carbon steel, stainless steel, titanium alloy, aluminum alloy and other materials.
Han’s Laser Intelligent Equipment Group has successively launched ultra-high power laser welding equipment such as 15kW, 16kW and 20kW, which can realize high-quality welding, single-side welding and double-side welding of 20mm stainless steel.
Tailored laser welding production line: realize the splicing of different materials, different thicknesses, and different strength materials.
Remote welding-welding without filler, realizing automatic welding in some narrow space areas.
Automatic laser welding of auto body parts, powertrain and transmission system components can effectively ensure the welding quality of key auto parts.

Cladding and Quenching

⑴Laser cladding: improve wear resistance, hardness, corrosion resistance, surface repair.
⑵Laser quenching: surface quenching strengthening and surface heat treatment of gears, shafts and molds.

3D laser printing

Powder-spreading 3D printing equipment, which can print stainless steel, titanium alloy, cobalt-chromium alloy and other materials, has high forming precision, and the dimensional accuracy can reach 20-100μm. It can form thin-walled parts with complex structure and wall thickness less than 0.2mm, medical, It is widely used in automobile and mold industries.
Powder-feeding additive-subtractive material composite manufacturing equipment, automatic switching between 3D printing and cutting processing, realizing the organic combination of additive manufacturing and subtractive manufacturing, complex curved surface 3D printing and five-axis machining, one-time forming, suitable for engine blades and structural parts , Mold manufacturing, etc.

laser cleaning

The high-energy laser beam is used to irradiate the surface of the workpiece, so that the dirt, rust or coating on the surface evaporates or peels off instantly. It can be used for industrial mold cleaning, rust, paint removal, etc. Quick and quick cleaning, no damage to the substrate, good accessibility.

At present, despite the rapid development of domestic laser equipment, most of the core components such as laser generators need to be imported. Domestic laser equipment R&D manufacturers and related scientific research units need to increase the research and development of core components such as lasers.

Automation, informatization, and intelligence are the needs of users and the direction of equipment development

The stamping industry is in the middle of the industrial chain. Under the background of rising raw material prices, rising labor costs, cost reduction by OEMs, and higher quality requirements, stamping companies in the middle of the industrial chain, especially small and medium-sized stamping companies, take the road of specialization and automation. The direction for enterprises to survive and develop in a highly competitive environment. Automation is one of the important ways for enterprises to reduce labor costs, improve product quality, and then improve competitiveness, and it is also the basis for realizing informatization and intelligence. Both parts manufacturers and equipment manufacturers are paying more and more attention to the development and application of automation, informatization and intelligence.

On-line monitoring of forming cracks of stamping parts: use sensing technology, optical photography technology, etc. to monitor temperature, lubrication conditions, parts status, etc., to judge whether parts are cracked, to ensure efficient operation of automatic stamping lines and reliable quality.
Equipment automation and intelligent control technology: various sensor detection of equipment, such as tonnage detection indication, mold loading height indication, control, equipment auxiliary vision system, etc.;
Mold digitalization and intelligent technology: sensor and signal processing technology, algorithm and industrial special software development and application, stamping CAE precision simulation technology research, body panel stamping die surface lean design (springback compensation, A surface reconstruction, press and mold deformation and other problems), the establishment of a digital design simulation platform for dynamic debugging of automotive molds, etc.
Intelligent manufacturing information cloud platform: equipment access, management, remote data collection, data storage graphic configuration, data display, data analysis, user management, etc.
Peripheral automation equipment of the press: various forms of automatic loading and unloading manipulators, automatic uncoiling feeders, line side material warehouses, mold warehouses, pneumatic blanking (waste) conveying systems, etc. These peripheral auxiliary process automation devices reflect the concept Artfully and crafted.

CAE virtual analysis technology is becoming more and more mature and widely used

The finite element analysis of sheet metal forming is an indispensable means for the development of modern sheet metal enclosure fabrication and processes. Analyze robustness. Some plate simulation analysis software has added new functions on the basis of the original.

Tribo Form: Factors and conditions affecting forming such as mold material, roughness, forming speed, and lubrication conditions are all taken into account, making the analysis results closer to reality and more accurate.

Robustness analysis: Use CAE software to conduct 6σ stability analysis, use big data to analyze the results of parameters within a certain range of variation, predict risks, improve and optimize forming conditions in advance, ensure the quality and cycle of subsequent production preparations, and obtain robust and reliable results in advance Results and scenarios.

Consider the interfaces and conversions between various software to make the software more convenient and faster to use.

Unfortunately, most of the simulation analysis software we use is imported software, and China is facing the embarrassing situation of lack of independent CAE software. The state should encourage and support capable universities, scientific research institutions, enterprises and institutions to develop domestic CAE software with core independent property rights, otherwise our sheet metal forming technology and industry will still be controlled by others.

Other technical developments and perspectives

Automobile lightweight technology and equipment have developed rapidly

In order to meet the requirements of energy saving and environmental protection, whether it is the national emission standards for fuel vehicles or the development of electric vehicles, vehicle lightweight is the only way. At present, the main ways to reduce the weight of automobiles are still two directions of efforts: materials and structures. In terms of lightweight materials, the application of high-strength plates, pipes, aluminum plates, and composite materials is still the main path. The development of future technology and equipment will still mainly focus on these new materials and new technologies. Typical examples include high-strength plate thermoforming, internal High pressure forming, roll forming, aluminum alloy forming, etc. At present, thermoforming and internal high pressure forming equipment have been localized, breaking the foreign monopoly situation. With the increase in demand, the research and development of new materials including composite materials, new process development and related equipment technology will usher in a stage of rapid development.

Increased demand for fine blanking parts

Due to the advantages of high section quality, high dimensional accuracy, good interchangeability and low production cost, fine blanking parts are more and more widely used in automobile, electronics and other industries. The competitiveness of the company still needs to be improved, and the fine blanking process, molds and equipment need to be improved and developed urgently. The development and application of fine blanking transfer die, the research and application of plate forging technology, and the precision stamping forming technology with more complex shapes and higher precision will be the key research and development directions in the field of fine blanking.

The process is more tightly integrated

Stamping, sheet metal fabrication, and precision extrusion (volume forming) are increasingly interconnected and interpenetrated, and many parts use stamping and extrusion composite processes. At the same time, many products and enterprises are closely combined with stamping and learn what is sheet metal fabrication processes.

In terms of technology and equipment technology: Jiangsu Zhongxing Xitian has developed the first multi-station press for punching and forging composite processing in Jiangsu Province with independent property rights (Figure 4), which combines stamping and forging processes and dies under forming Point finish material thickening and volume shaping. The structure of the press ensures rigidity and adopts servo control.

Agricultural machinery stamping product upgrade

my country is in a critical period of transformation from traditional agriculture to modern agriculture, which is both an opportunity and a challenge for the development of the domestic agricultural machinery industry. On the one hand, the demand for agricultural machinery in modern agriculture has increased significantly, coupled with government subsidy policies, the agricultural machinery industry has ushered in unprecedented development opportunities; on the other hand, large-scale, efficient, and complex agricultural equipment and core components required by modern agriculture still rely on imports International capital has entered the field of agricultural machinery in my country in a large scale. At the same time, people’s requirements for traditional agricultural machinery have changed from focusing on practicality in the past to not only focusing on practicality, but also focusing on visual effects and operating comfort, and put forward higher requirements for the shape and quality of agricultural machinery cab covers. Agricultural machinery companies need both products and processes, and the combination of stamping and sheet metal production processes to meet the needs of agricultural machinery sheet metal production and stamping parts in the new era.

The joint development and design of stamping technology and stamping equipment by equipment manufacturers and parts manufacturers has become the common wish of both parties. According to the product process requirements and characteristics, the equipment factory and the stamping factory cooperate to jointly research and develop suitable processes, molds, equipment, automation systems, etc. This requires equipment companies to have talents and capabilities in process development, and the requirements for equipment companies will become higher and higher.