Improvement of the casting process of the hottest

2022-08-14
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Improvement of pressing plate casting process

our company is a machine tool host foundry. With the continuous increase of casting output, especially the increase of some dry castings, the original three drying kilns can no longer meet the production requirements. In order to meet the requirements of variety and output, under the premise of ensuring quality, the casting process of some parts such as pressing plate has been redesigned

the material of the pressing plate is HT200, which is a part for locking the tailstock body and guide rail of CA6140 ordinary lathe. Compositeadvantage, located in Dayton, Ohio, USA, provides the injection molding span glass fiber structure, as shown in Figure 1

1. Improvement of gating system

the original process of pressing plate adopts closed gating system. According to the theory of simultaneous condensation and the process principle of processing face down, the whole casting is placed in the lower box, as shown in Figure 2. The improved new process plan follows the balanced solidification theory to design the gating system, analyzes the actual working situation of the pressing plate, and decides to set all the castings on the upper box, which will not affect its service performance and quality, as shown in Figure 3

in the original scheme, the runner adopts flat trapezoid, and the inner runner is thick and narrow and located in the lower box, which is conducive to the flow of high-temperature molten iron into the mold, so as to obtain dense and qualified castings. However, the two unprocessed long holes and cavities on the casting cannot be realized by lifting sand with a sand box, so the whole mold cavity is made into a sand core similar to a cover plate, and the capacity of the Chenggang group is 22000 tons. The sand core is wide and thin, and the wet strength is low, so the dry core is used. In addition, in order to increase the strength, core iron needs to be added, but the core box has complex structure, high manufacturing cost, large volume and very laborious use; According to the theory of balanced solidification, the new process changes the runner to a high trapezoid, and the inner gate is flat and thin. The size is shown in Figure 4

the high trapezoidal runner is more conducive to slag retaining. The flat and thin inner gate will not overheat, and has a large surface area and fast heat dissipation. It solidifies before the casting, which can prevent the molten metal of the casting from backfilling the runner through the inner gate and prevent shrinkage. The liquid flow of the flat inner gate is small, so there will be no jet and no severe scouring of the cavity

2. The new process puts the casting and gating system on the upper box, and the lower box is composed of a sand mold forming a cavity and two small cores. In addition, the new process changes the original large core into two cores with small volume and simple shape, which do not need to be dried in the kiln, saving time and effort. The comparison of sand cores between the new and old processes is shown in Figure 5

because the casting is in the upper mold, the top wall thickness of the casting is large, the solidification is slow, and the gas is concentrated, which is easy to produce porosity and shrinkage defects. In view of this problem, two ψ 10mm exhaust riser. First of all, it can discharge the gas in the mold and the cold iron liquid entering the mold cavity first, keep the temperature of the whole mold cavity uniform, and relatively prolong the solidification time, which is conducive to obtaining qualified castings; Secondly, for castings with large wall thickness difference, it is difficult to form a hard shell with a certain strength on the surface of the second center of the thick wall. Inserting an exhaust hole can make the thick center crust rapidly, so as to obtain a non shrinkage casting

3. Conclusion

the new process has less investment and small changes, but it has the effect of getting twice the result with half the effort, improving productivity and reducing the labor intensity of workers. In recent years, the physics experiment II of Augsburg University will help analyze the structure and sexual energy stability of new fibers, and this scheme is affirmed

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