The requirements for mold design and production are: accurate size, smooth surface; reasonable structure, high production efficiency, easy automation; easy manufacturing, high life, low cost; the design meets the process requirements and is economical and reasonable. The mold structure design and parameter selection must consider factors such as rigidity, guidance, unloading mechanism, positioning method, gap size, etc. The vulnerable parts on the mold should be easy to replace. For plastic molds and die-casting molds, it is also necessary to consider a reasonable pouring system, the flow state of molten plastic or metal, and the position and direction of entering the cavity. In order to improve productivity and reduce runner pouring losses, multi-cavity molds can be used, and multiple identical or different products can be completed in one mold at the same time. High-efficiency, high-precision, and high-life molds should be used in mass production.
The stamping mold should use a multi-station progressive die, and a carbide insert progressive die can be used to increase the life. In small-batch production and new product trial production, simple molds with simple structure, fast manufacturing, and low cost should be used, such as combined dies, thin plate dies, polyurethane rubber molds, low-melting-point alloy molds, zinc alloy molds, superplastic alloy molds, etc. The mold has begun to use computer-aided design (CAD), that is, to optimize the design of the mold through a complete set of computer-centered systems. This is the development direction of mold design.
Mold manufacturing is divided into flat punching dies and cavity dies with space according to structural characteristics. The punching die uses the precise size matching of the punch and the die, and some even have no gap matching. Other forging dies such as cold extrusion dies, die-casting dies, powder metallurgy dies, plastic dies, rubber dies, etc. are cavity dies, which are used to form three-dimensional workpieces. The cavity mold has size requirements in the three directions of length, width and height, and the shape is complex and difficult to manufacture. Mold production is generally single-piece and small-batch production, with strict and precise manufacturing requirements, and precision processing equipment and measuring devices are often used.
Flat punching dies can be initially formed by electrospark machining, and then the precision can be further improved by forming grinding, coordinate grinding and other methods. Forming grinding can be done by optical projection curve grinders, or surface grinders with reduction and repair grinding wheel mechanisms, or by special forming grinding tools on precision surface grinders. Coordinate grinders can be used for precise positioning of molds to ensure precise apertures and hole spacing. Computer numerical control (CNC) continuous track coordinate grinders can also be used to grind punches and dies of any curved shape. Cavity molds are often processed by copy milling machines, EDM and electrolytic machining. Combining copy milling with CNC and adding a three-way translation head device to EDM can improve the processing quality of the cavity. Adding aeration electrolysis to electrolytic machining can improve production efficiency.
