Recently, Haosen has succeeded in trial production of the hairpin motor stator using the new generation X-pin winding technology and has overcome key technical difficulties. It has outstanding leading advantages in various technical directions of the X-pin hair pin motor stator production line, is leading the innovation of the new generation hair pin motor stator manufacturing process, is paving the way for the industry, and is helping OEMs and Tier1s deliver high-quality cost-effective products. Haosen has already achieved X-pin stator sampling and mass production capabilities, and the research and development of mass production equipment has been completed.

X-pin, Evolution Direction of Hair Pin Motor Winding Technology

X-pin is named after the overlapping of two copper wires at its solder joint in an "X" shape. In the hair pin motor market, the current common winding forms are mainly Hair-pins, followed by I-pins. The common feature of these two winding forms is that the welding end needs to keep a straight line segment, which directly increases the height of the stator winding end.

However, the X-pin removes the straight line segment, which is reducing the height and volume of the stator end, more conducive to customers' spatial layout of the electric drive system and the complete vehicle. Compared with Hair-pins and I-pins, the heat loss of the stator copper wire is reduced as well as the volume and weight, which not only increases the power density, but also maintains the current flexible electromagnetic concept of the motor, which makes the "heart" of the electric vehicle and the kinetic energy stronger. Moreover, the X-pin stator production process does not require the cutting process, which has great technical advantages and can save cost for customers.

Manufacturing Difficulties and Haosen Innovative Solutions

Since there are many advantages, why hasn't X-pin technology been widely used on the market yet? At present, the development of X-pin is limited, and the reason lies in the process manufacturing end.

Firstly, the complexity of the X-pin stator wire sequence requires a variety of wire cut sections. Haosen innovates pin angle rapid forming technology, develops a new X-pin wire cut process, shapes multiple wire cut sections, meets consistency requirements, and achieves the transformation of intermittent production mode into continuous production mode, with an efficiency increase of 30%.

Secondly, there is no straight line segment at the welding end of the X-pin, and there is no gripping point for the twisting die during twisting, which has weak binding force on the copper wire and makes it difficult to control the twisting forming. Moreover, there is no cutting process to eliminate errors, and the accuracy of twisting directly affects the welding quality, bringing about high requirements for mechanical structure and motion control. In response, Haosen innovates the X-pin stator twisting and flaring technology, reshapes the mechanical structure of the twisting equipment, and configures a precise electrical control program. The flatness accuracy of the twisting is less than ± 0.5mm, ensuring the consistency of the copper wire after the twisting process and preparing for welding.

The third difficulty lies in the welding process. Taking Hair-pin as an example, welding involves melting a straight copper rod to form a solder joint, while X-pin forms a molten pool inward at the overlap of the copper wire. The welding area is very close to the insulation paint. How to effectively avoid damaging the paint during the welding process while ensuring the strength of the solder joint is a continuous challenge for the industry to make a break through.

Haosen promotes independent research and development, breaks through technological barriers, innovates efficient and stable welding technology for X-pin stators, adopts a flexible laser welding architecture concept, and integrates an independently developed advanced visual guidance system. The success rate of pre-welding visual guidance has reached 99.9%, significantly improving welding reliability. This technology can ensure that welding heat does not damage the paint, and make the pulling force of the solder joint reaches over 300N without blowing the protective gas. It will not break the wire under impact and in vibration. It can also ensure that the flow area of the solder joint is greater than 75% of the cross-sectional area of the copper wire, effectively giving full play to the performance of the motor.

X-pin stator welding auxiliary tooling technology has been innovated. The clamping method of conventional welding tooling is often rotary disc clamping. After cancelling the straight line segment, the space for clamping operation is very small, and the requirements for welding tooling design are very high. Haosen optimized the clamping method, proposed a new solution, and developed an integrated welding tooling to effectively clamp each solder joint copper wire, while avoiding laser damage to the bottom layer of copper wire paint. With self-developed pre welding visual guidance technology and post welding visual inspection technology, the X-pin stator welding quality is stable and the pass rate is high.

In addition, focusing on the technical pain points of low filling rate in the trickling process of the hair pin motor stator, which affects the insulation of the product, Haosen innovates efficient and flexible insulation technology to achieve continuous heating operation during the copper wire trickling process in X-pin stator production with precise heating temperature control, and trickling filling rate has reached 99.8%, which is still under continuous optimization.

The X-pin stator intelligent manufacturing technology independently developed by Haosen provides a strong support for the evolution of the hair pin motor technology. Haosen will work with industry partners to actively promote the application of X-pin technology in the new energy vehicle market, jointly develop new products with customers, provide customers with higher quality and more cost-competitive products, and achieve mass production of products as soon as possible. Haosen will adhere to technological innovation as always, inject Haosen power into the upgrading and development of the industry with more advanced technology and more stable solutions.