1. Main Contents of Core Design
As the cushion block belongs to the flat casting, its structure is complicated and there are many reinforcing ribs and grooves in the middle of the casting. Therefore, the block design is adopted for the formed sand core, which reduces the difficulty of manufacturing the sand core. Moreover, positioning and core head are set between the sand cores to keep the position of the sand core between the upper and lower molds fixed, effectively avoid misalignment and improve the accuracy of the casting.As shown in Figure 4, five cores are designed, of which 1#, 2#, 3# are placed on the same level and positioned with 4# and 5# cores.Cores 1 #, 2 #, 3 # are positioned by a bulge on the contact surface and cores 4 #, 5 # are positioned by steps.All cores in this casting belong to small cores, and the volume of cores is less than 0.05 m3. Therefore, there is no need to set core bones.
2. Core Exhaust
After the liquid metal enters the cavity, the sand core undergoes physicochemical reaction under the action of high temperature liquid metal, which generates a lot of gas in a short time, which seriously affects the casting accuracy. Therefore, it is necessary to exhaust the sand core.Combining with the position of the core, exhaust gas is set on all 5 cores, of which 4# and 5# are mainly exhausted through the upper surface. In addition to exhaust gas from the upper surface, exhaust gas from 1#, 2# and 3# cores is also set at the side contact position with the casting.