In the multi-station continuous stamping process of metal contact pieces, coaxiality is a core indicator for ensuring the functional stability of the metal contact piece. Excessive coaxiality deviation can lead to misalignment of contact parts, increased contact resistance, and even electrical connection failure. To solve this problem, a systematic guarantee solution needs to be constructed from four dimensions: mold design, process control, equipment precision, and inspection feedback.
The precision of mold design is the fundamental guarantee of coaxiality. Multi-station continuous stamping dies must adopt a high-rigidity structure, such as an insert-type template construction. By dividing the die cavity into independent modules and embedding them into the mold frame, the impact of overall mold deformation on coaxiality can be effectively reduced. Simultaneously, the positioning system should employ a combination design of double locating pins and a reference surface. The locating pins restrict horizontal freedom, while the reference surface constrains vertical displacement. Together, they ensure that the coaxiality deviation between the mold and the press spindle is controlled within a minimal range after mold installation. Furthermore, the mold's guiding mechanism must use high-precision guide pillars and guide sleeves, such as ball bearing guide pillar mold frames. Their fitting clearance is much smaller than that of ordinary guide pillars, significantly reducing minor offsets during the stamping process.
The stability of process parameters directly affects the dynamic performance of coaxiality. Stamping speed needs to be optimized based on material properties and part structure. While high-speed stamping improves efficiency, it may cause uneven material flow due to inertia, leading to coaxiality fluctuations. Low-speed stamping, while beneficial for controlling deformation, may affect accuracy due to material springback. Therefore, the optimal stamping speed range needs to be determined through trial molding and maintained constant during continuous production. Simultaneously, the blank holder force must be precisely matched to the material thickness and hardness. Insufficient blank holder force will cause material slippage, while excessive blank holder force may cause excessive local deformation; both will compromise coaxiality. Furthermore, the accuracy of the feeding system is crucial. Servo feeders, through encoders, provide real-time feedback on the feeding position, controlling feeding errors to a minimal range and preventing misalignment of subsequent processing references due to feeding deviations.
Equipment accuracy is the hardware support for coaxiality. The rigidity of the stamping press must meet the requirements of high-strength continuous stamping, and the straightness and repeatability of its slide movement trajectory must reach extremely high standards. If a punch press has clearances or wear, it can cause the slide to shift during the stamping process, leading to systematic coaxiality deviations in the parts. Therefore, regular precision inspection and maintenance of the punch press are necessary. This includes measuring the slide's movement trajectory using a laser interferometer and promptly adjusting or replacing worn parts. Furthermore, the flatness of the die mounting surface must be strictly controlled. Even slight unevenness or tilting on the mounting surface can cause elastic deformation of the die under stamping pressure, resulting in worsened coaxiality.
Inspection feedback is a closed-loop guarantee for coaxiality. During production, online inspection technology should be used to monitor coaxiality in real time. For example, non-contact measurements of key parts using laser scanners or vision inspection systems can quickly identify coaxiality deviation trends. When inspection data exceeds the allowable range, the system automatically triggers process adjustments or shutdown for maintenance to prevent batch defects. Simultaneously, a comprehensive traceability system must be established to record the die status, process parameters, and inspection data for each batch of parts. When coaxiality problems occur, data analysis can quickly pinpoint the cause, distinguishing between die wear, equipment malfunction, and material fluctuations, allowing for targeted improvement measures.
Material consistency indirectly affects coaxiality. If the material thickness is uneven or the hardness fluctuates significantly, the material flow during stamping will be non-uniform, leading to unpredictable part deformation. Therefore, raw materials must be rigorously inspected to ensure that their thickness tolerances, hardness uniformity, and other indicators meet requirements. Furthermore, the surface quality of the material also needs attention; surface scratches or oxide layers may cause changes in friction during stamping, thus affecting the stability of material flow.
Environmental factors are equally important to manage. Fluctuations in workshop temperature and humidity can cause thermal expansion and contraction of materials or changes in mold dimensions. For example, material expansion at high temperatures may reduce the stamping gap, causing excessive local deformation; material contraction at low temperatures may lead to insufficient stamping, both of which can compromise coaxiality. Therefore, workshop temperature and humidity must be controlled within a stable range, for example, by maintaining a constant temperature and humidity environment through an air conditioning system to reduce the interference of environmental factors on the stamping process.
Personnel skills and operating procedures are the soft guarantee for coaxiality. Operators must be familiar with the mold installation, debugging, and maintenance procedures. For example, special tools must be used when changing molds to avoid deformation caused by rough handling. During production, the mold condition must be checked regularly to promptly identify and handle any abnormalities. In addition, standardized work instructions must be established to clearly define the operating requirements and quality standards for each workstation, ensuring that all operators follow uniform standards and reducing the impact of human factors on coaxiality.
