Principles and technical requirements for precision casting
Precision casting for molding
The temperature of the injection wax injection is mostly below the melting point. At this moment, the mold is a slurry or paste coexisting with liquid and solid. In the slurry -shaped mold guess, the amount of liquid phase is significantly exceeded, so it still retains the activity of liquid. Under this situation, the appearance of the melting mold has a lower roughness, and it is not easy to show the appearance disadvantages caused by the turbulent and splash. The temperature of the paste molding mold is lower than the slurry mold. It has lost its movement. Although the disadvantage of the appearance is rare, it has a high appearance roughness.
When the mold is injected, the low mold temperature and pressure type work temperature should be selected as much as possible under the condition of ensuring good filling. The larger the choice of pressure, the better. Although the pressure of the melting model of the pressure is small, the pressure and pressure injection speed are too large, which will make the melting mold appearance not smooth, producing "bubble" (the inflated under the molten molten skin bubbles), together , Make the mold spatter showing the disadvantages of cold partitions. In the process of molding, in order to prevent the mold adhesion of the mold and improve the smoothness of the melting mold, the typical agent should be used, especially for the rosin base mold.
Melving mold casting kneading molding
Kneading molding and kneading the mold under low temperature plasticity, under high pressure to mold to reduce and prevent the melting mold shortening. The horizontal material when kneading is semi -solid or solid. This mold is relatively hard under normal conditions, but it can move under high pressure. Its characteristics are large viscosity. Therefore, the details of the pressure when kneading depends on the viscosity of the mold and the resistance of the activity in the injection hole and the cavity. The greater the viscosity of the mold, the smaller the pores, the larger the cavity scale, and the smaller the cross -sectional area, and the longer the mold itinerary, the greater the resistance during the mold activity, the higher the problem of kneading. Sending semi -solid modes knead the molding molding, the solidification time of the fuse is shortened. Therefore, the output rate is particularly suitable for the production of castings with thick cross -section.
During the lathe processing, the effect of the heart is usually used. The three -claws of the lathe may be tightly tightened, and then the mechanical parts are processed. Together, for the effect of not loosening and reducing the internal radial force during the stress, the clamping force must be greater than the cut force of the mechanical. The clamping force has increased with the increasing cutting force, and decreased by it. This operation can stabilize mechanical parts during processing. However, after the three -claws may be loosened, the processed mechanical parts will be far from the original. Some present polygons, and some show oval shapes, with large errors.
Technical requirements for precision casting
Precision casting manufacturers believe that, regarding small castings, the production line of high -voltage -free modeling machines with horizontal or vertical types can be selected for small castings or vertical types.
Regarding the mid -parts, a variety of box high -voltage modeling machine production lines and gas -rushing modeling lines are selected. With the requirements of fast and high -precision modeling production lines, the core method can be selected: cold core box, hot core box, shell core and other core methods. Essence
The medium -batch large -scale castings can consider using the resin to use hard sand shapes and cores.
Single -type small -scale heavy casting, craftsmanship is still an important way. The craftsmanship can be more flexible for various cluttered requirements, and it is not required to require many craft equipment. Can use water glass sand, VRH method water glass sand, organic ester water glass from hard sand, sticky sticky type, resin from hard sand and cement sand types; Quickly put into production.
Batch or long -term production products are more appropriate to use multi -box modeling and box -chopping modeling method. Although molds and sandboxes have begun to contribute high, they can be compensated in terms of saving work hours and improving product quality. Low -voltage casting, die casting, centrifugal casting and other casting methods, because the price of equipment and molds is expensive, it is only suitable for mass production. Conditions should be suitable for examples such as large -scale machine tools. Generally, the group core modeling method is generally selected, the appearance and sandbox are not made, and the core is set in the pit.
Different corporate production conditions (including equipment, venues, employee quality, etc.), habit, and experience in gathered are different. They should consider what products and not suitable for these conditions according to these conditions. The accuracy requirements and costs have different casting accuracy, and the initial capital contribution and production rate are not consistent, and the economic benefits are also different at the end. Therefore, it is necessary to take into account all aspects and deal with the selected casting methods to make preliminary capital budgets to determine the casting force method that can be found in the casting requirements.