In the manufacturing of modern home appliances, industrial machinery, and other equipment, assembly is no longer a task requiring a large amount of time and manpower. As 3C products become smaller and smaller, and users demand higher quantities and faster product updates, the level and speed of manual assembly are far from meeting the requirements. Therefore, automated assembly lines have emerged.
Of all assembly tasks, tightening screws is the most labor-intensive and tedious. A single everyday mobile phone requires hundreds of screws for structural tightening. The lithium batteries in new energy vehicles have thousands of screws, and most importantly, the angle, torque, and other parameters of each screw must be precise. If this were done manually, the labor costs would be limitless, and the risk of product defects would increase significantly. Therefore, a tightening system is an essential piece of equipment in all assembly processes.
Currently, tightening systems on the market are generally divided into servo tightening systems and coreless motor tightening systems.
Servo tightening system:
A servo tightening system is an automatic tightening system that allows the torque, angle, and other outputs of a regular screwdriver to change arbitrarily according to an input signal (or a fixed value). The so-called servo tightening system mainly relies on the precise pulse positioning of a servo motor to perform precise tightening work. It can be understood that the servo motor rotates by a corresponding angle after receiving a pulse to achieve torque and positioning control. The pulses emitted by the servo motor after rotation correspond to the received pulses, ultimately achieving feedback of torque and other values during the tightening process, realizing closed-loop control.
The basic servo tightening system consists of three parts: a controller, cables, and a servo screwdriver.
1. Controller
It includes a built-in power supply, servo driver, display screen, and main control board. Its main functions are to issue commands to the screwdriver, drive the servo motor, and display feedback values.
2. Cables
Its main functions are to transmit instructions and provide feedback data.
3. Servo screws
In addition to the accessories of a regular screwdriver, it also has a built-in servo motor, whose main function is to perform tightening operations according to instructions and to provide feedback on torque, angle and other values.
Main applications: Servo tightening systems are mainly used in assembly applications that require high precision, zero error, and data feedback. Their disadvantage is due to the characteristics of servo motors, which make them unsuitable for tightening applications that require large inertia and high torque.
Hollow cup motor tightening system:
The key feature of the coreless motor tightening system stems primarily from the coreless nature of the coreless motor. As is well known, conventional linear motors, stepper motors, and servo motors all require a rotor with an iron core. The coreless nature of the coreless coreless motor makes it significantly smaller and lighter than ordinary motors. Furthermore, its performance is superior to that of ordinary iron-core motors; while the energy conversion rate of ordinary iron-core motors is around 70%, coreless motors can reach 90%. Its response speed also far exceeds that of iron-core motors.
This characteristic makes the electric screwdriver in the coreless motor tightening system very lightweight. Currently, the coreless motor tightening system on the market is mainly based on the structure of a screw gun, which can also provide feedback on tightening data when equipped with an encoder and controller.
However, due to the higher cost of coreless motors, the tightening system of coreless motors is naturally more expensive than that of servo tightening systems. The cost of a coreless motor tightening system from foreign brands is generally around 30,000 to 40,000 yuan. Therefore, manufacturers that do not have high requirements for torque usually choose the cheaper servo tightening system.
Main applications: Suitable for high-torque applications such as the automotive industry. Well-known brands like Mato and Atlas Copco use coreless motors in their tightening systems, primarily targeting the automotive industry. However, in terms of precision requirements, it still doesn't reach the level of a servo motor.
A complete tightening system, in addition to the basic tightening system, also needs to be equipped with a feeder, PLC, computer, and display screen. This allows it to be combined into a complete automatic tightening system for an automated production line.
