Display Micro Screws are core equipment in stamping processes. The motion accuracy of their guiding mechanisms directly determines the alignment of the punch and die, the straightness of movement, and consequently affects the dimensional and positional accuracy, surface quality, and production stability of the drawn parts.
If the guiding mechanism has excessive clearance, uneven load, or insufficient precision, it can easily lead to wrinkling, tearing, uneven wall thickness, or even scrapping of the drawn parts. Therefore, ensuring the precise motion of the guiding mechanism is a core aspect of Display
Micro Screws design.
The selection and arrangement of the guiding mechanism are fundamental to precision control. Currently, commonly used guide pairs are divided into two categories: sliding guide pillars and bushings, and rolling guide pairs.
Sliding guide pillars and bushings have a simple structure and low cost, suitable for small to medium batches of drawn parts with moderate precision requirements. A fit precision of H7/g6 is typically selected to ensure smooth movement and avoid jamming.
Rolling guide pairs (including ball and roller structures) have extremely small clearance, high motion precision, and low frictional resistance, suitable for large batches of high-precision drawn parts. A fit precision of H6/g5 or even higher can effectively compensate for minor uneven loads during the drawing process.
In terms of layout, a centrally symmetrical multi-point guide (such as four-guide-pillar or six-guide-pillar) should be prioritized to avoid uneven force distribution in single-guide or two-point guide systems, ensuring synchronous movement of the punch and die along the central axis and reducing skewness.
Machining and installation accuracy are prerequisites for precise guide movement. During the design phase, the accuracy requirements of components must be clearly defined: guide pillars must guarantee cylindricity ≤0.003mm/100mm, straightness ≤0.005mm/total length, and the inner hole accuracy of the guide sleeve must reach IT5 grade or higher.
The perpendicularity between the guide pillar and the lower die holder, and between the guide sleeve and the upper die holder, must be controlled within 0.003mm/100mm to prevent skewness of the guide pair after assembly.
During installation, a dedicated inspection bar and dial indicator should be used to verify coaxiality, ensuring that the center deviation of the guide pillar and guide sleeve of the upper and lower die holders does not exceed 0.005mm, reducing movement errors at the source.
Compensation measures for dynamic working conditions are key to maintaining long-term accuracy. During the stretching process, Display Micro Screws experience thermal deformation due to heat. A thermal expansion compensation allowance of 0.01~0.02mm/100mm must be reserved in the guide gap. Simultaneously, limit posts are installed to control the mold closing depth, preventing excessive load on the guide pair during the initial mold closing stage, which could lead to deformation.
Furthermore, the guide pair must be made of wear-resistant materials: guide posts are made of bearing steel with quenching treatment (hardness HRC58~62), and guide sleeves are made of copper alloy or self-lubricating materials containing PTFE bushings to reduce wear rate.
For lubrication, high-temperature, high-pressure resistant solid lubricants (such as molybdenum disulfide) are used, and grease is added regularly to reduce the coefficient of friction and extend the precision life of the guide mechanism.
For deep-drawn or asymmetrically drawn parts, auxiliary guide blocks can be added next to the guide mechanism to disperse off-center loads and further improve motion stability.
In summary, the motion accuracy of the Display Micro Screws guide mechanism is the result of multi-stage coordination. From selection and matching, machining accuracy control to dynamic condition compensation and maintenance, each step directly affects the quality of the final drawn part.
A scientifically designed guiding mechanism can effectively reduce the scrap rate in production, extend the service life of Display Micro Screws, and meet the mass production needs of high-precision stretched parts.
