Investment casting is widely used in production, mainly because paste molds are smaller than liquid molds, with faster solidification speed and higher productivity. In the production process of wax molds and precision castings, the dimensional stability and degree of deformation of wax molds have a significant impact on the quality of precision castings. The parts that are prone to deformation are blocked by the wax injection mold from the first program to restrict shrinkage deformation. After opening the door, the root is attached to the door, and after pressing the wax for cooling, water and other effective measures are taken to ensure that the wax mold is in good condition. Numerous production practices have proven that these preventive measures are effective and necessary.
Investment casting is widely used in production, mainly because paste molds are smaller than liquid molds, with faster solidification speed and higher productivity. In the production process of wax molds and precision castings, the dimensional stability and degree of deformation of wax molds have a significant impact on the quality of precision castings. The parts that are prone to deformation are blocked by the wax injection mold from the first program to restrict shrinkage deformation. After opening the door, the root is attached to the door, and after pressing the wax for cooling, water and other effective measures are taken to ensure that the wax mold is in good condition. Numerous production practices have proven that these preventive measures are effective and necessary.
1. Set obstacles inside the wax mold to limit the shrinkage deformation of the precision casting right page structure. Due to the need to ensure good door rotation, two ф 10.5mm hole requires coaxiality. The original production process was to press the wax, cool the mold in water for 30 minutes, and then remove the wax mold. Pins for precision castings pass through ф The two holes with a diameter of 10.5mm are not coaxial, and the pin shaft cannot be inserted, requiring 100% correction without any deformation patterns, greatly increasing the workload of correction and seriously delaying production progress. In response to this situation, the process has been improved, and through calculation, 10 ф 10.80-0.1mm pin shaft, then according to the correct page wax mold, the pin shaft is ф Insert a 10.5mm hole into the wax mold, then place it in water and cool it for 30 minutes. There are two methods to make these wax molds: one is to repair the wax mold and directly stick it to the back of the tree, and the other is to stick the wax mold to the top of the tree and stretch it. The inspection of the pin shaft in precision casting production only shows a slight deviation in one of the two holes, while the rest fully meets the requirements. The right page has a deviation, which can be slightly corrected to meet the requirements. After classification, it was found that the first method met the production requirements without adhesion and stretching, and can be put into mass production.
The measure of sticking the gate after the root opening of the gate is a DNl50 flange structure with symmetrical structure and uniform wall thickness. If the door is opened directly, because the door is thick and large, forming a wall thickness difference with the wax mold body, not only is it difficult to remove the wax mold from the mold, but it also deforms the mold due to improper methods; In addition, during the cooling process of the wax mold, uneven wall thickness causes shrinkage deformation. Therefore, in summary, for DNl50 flanges, a pre-set gate root (height: 1.0-1.5mm) is used, and then the gate is glued to avoid uneven wall thickness caused by excessive gate thickness on the wax mold, leading to asynchronous shrinkage deformation.
3. Wax cooling method: After pressing the wax, attention should also be paid to the selection of cooling method, usually using air or cold water for cooling. Cooling in cold water can force the shape of wax molds, and some three end or two end flanges, such as the body of DN40 flange gate valves, are cooled in a water tank under normal production conditions, resulting in a very different distance between the two flange wax molds L1 and L2, which can reach 2.0-2.5 millimeters.