In order to solve the increasingly prominent energy and environmental issues, the new energy industry is receiving more and more attention from all over the world. The lithium battery industry has developed rapidly as a national key support for new energy projects. In the past two years, the synergistic effects of various central and local support policies have gradually emerged. China’s new energy vehicle market has seen unexpected growth and growth, and has driven the rapid growth of upstream and downstream enterprises in the industrial chain, especially the lithium battery industry. The further increase in sales of energy vehicles, the industry expects that lithium batteries will enter the stage of tight supply in 2018, strong demand puts higher requirements on the technology, process and performance of lithium batteries, further highlighting the lack of capacity. At present, most of the internationally used laser welding technology to weld the battery cells and protective plates of lithium batteries. With the continuous development of the manufacturing industry, vigorously develop high-end manufacturing technology, how to improve the technical level of laser technology in the field of lithium battery manufacturing, how to upgrade and optimize the overall performance of laser welding equipment, has become the focus of research of various manufacturers. In the moving platform part, the linear motor has better dynamic performance than the ball screw, more precise positioning accuracy and repeat positioning accuracy, higher stability and lower maintenance cost. Replacing the ball screw motion platform with a linear motor drive platform has become an inevitable trend.
Laser welding technology features and difficulties:
Laser welding is a fusion manufacturing process that turns raw materials such as positive and negative materials, separators and electrolytes into zero. It is the key process in the entire lithium battery production process. Laser welding uses the excellent directionality and high power density of the laser beam to work. Laser welding has the following characteristics: high laser power density, high melting point, refractory metal or two materials can be welded; small spot light spot, fast heating speed, short action time, small heat affected zone, negligible thermal deformation; laser welding It belongs to non-metal welding, no mechanical stress and mechanical deformation; laser welding device is easy to be connected to the computer, can be accurately positioned, and realize automatic welding. Lithium battery modules can greatly reduce contact resistance, reduce energy consumption, and improve battery safety, reliability and service life through efficient and precise laser welding. However, laser welding requires high precision assembly of the weldment and requires that the position of the laser beam on the workpiece cannot be significantly offset. If the assembly accuracy of the weldment and the positioning accuracy of the laser beam do not meet the requirements, it is easy to cause welding defects and affect the welding quality. The characteristics of laser welding technology and the structural performance of lithium batteries place higher and more precise requirements on the motion platform of laser welding equipment.
Technical characteristics and difficulties of the two-axis linkage linear motor platform:
The essence of a linear motor is to flatten the rotary motor and connect it directly to the drive load. It replaces all mechanical transmissions such as ball screws, racks and gears, belts and pulleys, and gearboxes, eliminating backlash and mechanical transmission-related problems. The utility model has the advantages of simple structure, wide speed regulation range, excellent dynamic performance, high positioning precision, safety and reliability, low running noise, no wear, maintenance-free and unlimited travel.
The dual-axis linear motor platform of Ling monkey can reach 5g acceleration and repeat positioning accuracy up to 1μm. Based on the deep optimization structure design, the unique self-written control algorithm is used to track the detection speed fluctuation and make subsequent compensation to make the double-axis linear motor. Under the condition of high speed and small arc motion, the speed fluctuates below 3%, and the trajectory deviation is on the micrometer level. Fully meet the requirements of lithium battery laser welding for platform accuracy, acceleration, speed and other performance.
Recently, a laser welding equipment manufacturer's equipment movement platform uses a screw rod module, but the welding quality of the equipment is not guaranteed when the acceleration is 1g and the speed is mentioned at 100mm/s. The two-axis linkage linear motor is now required. The platform replaces the screw platform module and explicitly requests the following error test report including the arc angle. However, the customer does not understand the linear motor motion platform, so he seeks a solution from our company.
After several technical exchanges with the customer, the first version of the two-axis linkage linear motor motion platform module was designed after fully understanding the characteristics information of the customer equipment, but the required circular motion angle of the motion platform of the motion platform is small, and The speed and accuracy requirements are high. After the optimization of the structure of the two-axis linear motor platform, the customized algorithm is used to control the coupling of the upper and lower axes. After detailed system testing, the customer's needs are finally met, and the customer's needs are upgraded and optimized. Laser welding equipment makes its equipment welding speed, precision and stability in the leading position in the same industry.
Customer requirements are as follows:
Linear motor demand list
Customer Name: A laser welding equipment integration application industry: Lithium battery laser welding
Contact Phone: E-mail:
movement
Axis movement mode: □ horizontal √ □ vertical
Speed planning curve: □1/3-1/3-1/3 trapezoidal wave □1/2-1/2 triangle wave
Total travel stroke: 270mm for the upper shaft and 300mm mm for the lower shaft
Total running time: 1.8ss
Maximum operating speed: 0.5 m/s
Maximum operating acceleration: 3g m/s2
Load weight: 30 kg
Precision
Positioning accuracy: ±5 μm
Repeat positioning accuracy: ±1 μm
Resolution: 0.1 μm
Amplifier and power supply
Maximum current: 6.3 A
Voltage: 220 VAC □50 Hz √ □60Hz
Use environment
Ambient temperature: room temperature °C
Maximum allowable temperature rise: 130 °C
Whether it is in a dust-free environment: □Yes □No
Whether to allow water cooling or air cooling: □ Yes □ No √
Whether it is a vacuum environment: □Yes □No
Overall hardware design and verification
System Configuration:
The two-axis linkage linear motor motion platform is mainly composed of four parts: linear motor, detection feedback, drive control and protection device. The motion platform adopts a coreless linear motor, and the motion is smooth without cogging force; the detection feedback is composed of grating or magnetic grid, Hall, and temperature control; the platform module is a high-invasive driver, and the protective device is composed of an organ shield. High-performance towline, photoelectric sensor, and excellent rubber hard limit are formed to fully protect the safety and reliability of the motion platform. The effect of the model is shown in Figure 2:
Figure 1: Model of a two-axis linkage module
The main performance parameters of the two-axis linear motor are shown in Figure 3:
Figure 2: Performance parameters of the two-axis linkage module
Verification Test
According to the movement characteristics and trajectory of the customer equipment, in order to ensure the stability and reliability of the customer equipment during the operation, we have repeatedly verified the requirements and issued relevant verification reports. The parameters of the sports platform are in line with customer requirements. And done a fatigue test equivalent to 1.5 years of continuous operation of the equipment, no abnormalities in all parameters.
After many technical exchanges, structural optimization, and test verification, the Monkey Dual-axis linear motor motion platform met the customer's requirements in only two weeks, met the delivery conditions and debugged and installed on-site at the customer's site until the customer's equipment was completely completed. Shipment, we also actively track the operation status of our products in the customer equipment terminal and various data, providing reliability reports for customer equipment in real time.
The customer's "non-standard private order" two-axis linkage linear motor motion platform module adopts independently developed BUM series ironless linear motors. The linear motors have high thrust, low motion quality and no cogging. The effect, non-magnetic attraction, etc., especially when walking the curved arc track, can achieve low speed fluctuation under high speed and small arc angle. After using the two-axis linkage linear motor motion platform, the welding speed is increased by 50%, the welding quality at the arc corner is improved, the performance of the customer's overall equipment is upgraded and optimized, and the sales of the customer equipment are increased. The sales of motor modules have truly achieved a win-win value.
In addition to the above applications, the linear motor platform module also has an ultra-thin cross-snake motion platform module for use in the medical industry. Its overall size is only a ballpoint pen size; visual inspection in the 3C industry and rapid on the dispensing platform Mobile four-axis linear motor module; LPS series single-axis platform module for machine tool and fast handling industry; SP standard series single-axis platform module that can completely replace screw directly.
With the increasingly demanding requirements of the manufacturing industry, modern advanced manufacturing equipment is moving toward high speed, high precision, fast response, and large stroke. This inevitably requires a responsive, high-speed, lightweight drive system. Because the traditional feed mode—“rotary motor + ball screw” requires intermediate transmission links such as couplings and lead screws, the overall system is not rigid enough and the elastic deformation is severe. Moreover, because the accuracy of the lead screw in the "indirect transmission" is difficult to be improved, and there is a disadvantage of the back gap, the conventional feed system cannot meet the above requirements. Relatively speaking, the linear motor has the advantages of simple structure, convenient installation, no contact, no wear, and the like, and is superior to the rotating motor in other performance indexes such as accuracy, repeated positioning accuracy, rigidity, working life and the like. Its main promotion and high-speed, high-precision rotary motors can not meet the requirements of the occasion. Modern linear motor technology is becoming more and more mature, and it is bound to replace the traditional "rotary motor + screw" transmission mode.
