Raising the technological level of laser technology in the field of lithium battery manufacturing has become the focus of current research by various manufacturers.

In order to solve the increasingly prominent problems of energy and environmental protection, the new energy industry is increasingly drawing attention from countries around the world. Lithium battery industry as a national key support for new energy projects has developed rapidly. In the past two years, the synergy effects of various supporting policies of the central government and local governments have gradually emerged. China's new energy vehicle market has exceeded expectations and growth, and has driven the rapid growth of upstream and downstream enterprises in the industrial chain, especially the lithium battery industry. With the further increase in the sales of energy vehicles, the industry expects that lithium batteries will enter the tight supply phase in 2018. The strong demand puts higher requirements on the product technology, process, and performance of lithium batteries, further highlighting the lack of production capacity. At present, most of the world adopts advanced laser welding technology to weld lithium battery cell cores and protection plates. With the continuous development of the manufacturing industry, vigorously developing high-end manufacturing technologies, how to improve the technological level of laser technology in the field of lithium battery manufacturing, and how to upgrade and optimize the overall performance of laser welding equipment have become the focus of current research by various manufacturers. In the motion platform part, the linear motor has better dynamic performance than the ball screw, more precise positioning accuracy and repeated positioning accuracy, higher stability, and lower maintenance costs. It has become an inevitable trend to replace the ball screw motion platform with a linear motor transmission platform.

Laser welding is a fusion manufacturing process in which raw materials such as anodes and cathodes, separators, and electrolytes are integrated and is a key process in the entire lithium battery production process. Laser welding works by using the laser beam's excellent directionality and high power density. Laser welding has the following characteristics: High laser power density, can weld high melting point, refractory metal or two kinds of materials; Focusing spot is small, heating speed is fast, action time is short, heat affected area is small, thermal deformation is negligible; laser welding Non-metallic welding, no mechanical stress and mechanical deformation; laser welding device is easy to computer online, accurate positioning, automatic welding. The lithium battery module can greatly reduce the contact resistance, reduce the energy consumption, and improve the safety, reliability and service life of the battery through efficient and precise laser welding. However, laser welding requires that the weldment has high assembly accuracy and that the position of the laser beam on the workpiece must not be significantly shifted. If the accuracy of the weldment assembly and the laser beam positioning accuracy 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 put forward higher and more precise requirements for the motion platform of laser welding equipment.

The essence of the linear motor is to lay the rotary motor flat and connect it directly to the drive load. It can replace all mechanical transmission parts such as ball screws, racks and gears, belts and pulleys, and reduction gearboxes, eliminating backlash and problems associated with mechanical transmission. The utility model has the advantages of simple structure, wide speed range, excellent dynamic performance, high positioning accuracy, safety and reliability, low running noise, no wear, maintenance free and infinite travel.

The monkey's dual-axis linear motor linear motor has an acceleration of 5g and repeatability of positioning up to 1μm. Based on the depth-optimized structural design, it uses a unique, self-authoring control algorithm to track the detection speed fluctuations and make subsequent compensations to make the biaxial linear motors. Under the conditions of high speed and small circular arc movement, the speed fluctuation is below 3%, and the trajectory deviation is even at the micron level. Fully meet the lithium battery laser welding platform accuracy, acceleration, speed and other performance requirements.

Recently, there is a screw module for the equipment movement platform of a laser welding equipment manufacturer. However, the welding quality of the equipment cannot be guaranteed when the acceleration is 1g and the speed is 100mm/s. Now a dual-axis linear motor is required. The platform replaces the screw platform module and explicitly provides a follow-up error test report including a circular angle of rotation. However, the customer does not understand the linear motor motion platform, and therefore seeks a solution from our company.

After several technical exchanges with customers, after the complete understanding of the characteristic information of the customer equipment, a preliminary version of the dual-axis linear motor motion platform module was designed. However, the required circular arc angle of the motion track of the motion platform is required to be small, and Its speed and accuracy are relatively high. After our company optimizes the structure of the double-shaft linkage linear motor platform, the custom-written algorithm controls the coupling of the upper and lower two axes. After detailed system testing, it finally meets the needs of customers and upgrades and optimizes the customer's requirements. Laser welding equipment, its equipment welding speed, accuracy and stability in the same industry leading position.

Customer requirements are as follows:

Linear Motor Requirements Table

Customer Name: Laser welding equipment integrated application industry: Lithium battery laser welding

Contact Phone: Email:

movement

Axis movement mode: □ horizontal √ □ vertical

Speed planning curve: □ 1/3-1/3-1/3 trapezoidal wave √ 1/2-1/2 triangle wave

Total movement stroke: Upper shaft 270mm, lower shaft 300mm mm

Total operating time: 1.8ss

Maximum operating speed: 0.5 m/s

Maximum operating acceleration: 3g m/s2

Load weight: 30 kg

Accuracy

Positioning accuracy: ±5 μm

Repeatability: ±1 μm

Resolution: 0.1 μm

Amplifiers and Power Supplies

Maximum current: 6.3 A

Voltage: 220 VAC 50 50 Hz √ □ 60Hz

Use environment

Ambient temperature: Room temperature °C

Maximum allowable temperature rise: 130 °C

Is it in a dust-free environment: □Yes √ □No

Whether to allow water cooling or air cooling: □Yes □No √

Is it a vacuum environment: □Yes √ □No

Overall hardware design and verification

The two-axis linkage linear motor motion platform consists of four parts: linear motor, detection feedback, drive control, and protection device. The motion platform uses a coreless linear motor, smooth motion without cogging force; detection feedback consists of a grating or magnetic grid, Hall, temperature control; this platform module is a high-gear drive, protective device by the organ shield, High-performance drag chains, photoelectric sensors, and excellent rubber hard limit composition, fully protect the safety and reliability of the motion platform. The model effect is shown in Figure 2:

Fig. 1: Two-axis linkage module model

The main performance parameters of the double-shaft linkage linear motor are shown in Figure 3.

Figure 2: Two-axis linkage module performance parameters

According to the movement characteristics and trajectory of the customer's equipment, in order to ensure the stability and reliability of the customer's equipment in the course of operation, we have done a number of needs verification and issued a relevant verification report, the parameters of the sports platform are in line with customer needs , And done the equivalent of 1.5 years of continuous fatigue testing equipment, all parameters are no exceptions.

After several technical exchanges, structural optimization, and test verification, the Monkey Monkey twin-axis linkage linear motor motion platform has met customer requirements in just two weeks, fulfilled the delivery conditions and real-time debugging and installation at the customer's site until the customer's equipment is completely In shipment, we also actively tracked the operation status of our products at customer equipment terminals and various data, and provided reliability reports for customer equipment in real time.

The customer's "non-standard private customized" dual-axis linear motor motion platform module uses the independently developed BUM series ironless linear motor on both the upper and lower axes. This series of linear motors has high thrust, low moving mass, no tooth slot Effect, non-magnetic attraction and other characteristics, especially when taking a curved arc track, can achieve low-speed fluctuations at high speed and small arc angle. After using the double-shaft linkage linear motor motion platform, the welding speed is increased by 50%, and the welding quality at the circular arc corner is improved. The performance of the customer's overall equipment is upgraded and upgraded, and the sales volume of the customer equipment is also increased. The sales of motor modules have truly achieved a win-win result.

In addition to the above application, the linear motor platform module also has an ultra-thin cross-snake motion platform module applied in the medical industry. Its overall size is only the size of a ballpoint pen; the visual inspection in the 3C industry and the rapidity in the dispensing platform Mobile 4-axis linkage linear motor module; LPS series single-axis platform module in machine tool and fast-moving industries; SP standard series single axis platform module that can completely replace the screw rod, etc.

With the increasingly demanding requirements of the manufacturing industry, modern advanced manufacturing equipment is developing toward high speed, high precision, quick response, and large travel. This inevitably requires a responsive, high-speed, and lightweight drive system. Since the traditional feed method, "rotary motor + ball screw" requires intermediate transmission links such as couplings and screws, the overall system rigidity is insufficient and the elastic deformation is severe. And because of the disadvantages of the "indirect drive" in which the accuracy of the screw is difficult to increase and there is a backlash, the conventional feed system cannot meet the above requirements. In contrast, linear motors have the advantages of simple structure, easy installation, no contact, no wear, etc., and are superior to rotary motors in accuracy, repeatability, stiffness, working life and other performance indicators. Its main promotion and high-speed, high-precision rotary motors can not meet the requirements of the occasion. The modern linear motor technology has become increasingly sophisticated, and it is bound to replace the traditional "rotary motor + screw" transmission mode.