Production conditions and technical requirements
Casting material: HT200
Casting shape: there are two bosses on the ground, hollow in the middle and arc-shaped frame in the upper. The structure is shown in Figure 1.
Fig. 1 Structural diagram of shaft support
Ground thickness 5mm, boss height 7mm
Casting weight: 5kg
The shaft bracket is used to support the shaft parts. There are two bosses on the bottom. The middle part is hollow and irregular in shape, and the upper semicircular groove is used for the placement of shaft parts.
Main technical requirements:
The shaft support is a small thin-wall casting. According to its purpose, the shaft bracket should have certain mechanical properties and can bear certain load. HT200 casting can meet the application requirements;
The overall dimension accuracy of the shaft support body is not high, but the parallelism and thickness of the bottom surface and the height gauge of the boss shall meet the assembly requirements, and shall have a certain surface finish to meet the aesthetic requirements;
The semicircular groove matched with shaft parts shall be machined after casting to meet the dimensional matching requirements.
Casting process type:
Sand casting, three box molding
Mold design and parting surface selection:
The design mold is shown in Figure 2. The middle hollow structure and upper semicircular structure of the casting are made with a mold core.
Fig. 2 Schematic diagram of model, parting surface and box surface
According to the casting structure and shape, three boxes are selected for molding. The casting box surface is the mold parting surface, as shown by the dotted line in Figure 2.
The middle hollow and upper semicircular structure of the casting need to be made of core, and a total of two cores are required.
The shape of the sand core used to create the middle hollow structure is the same as that of the hollow part of the casting.
There shall be a fixing device at the rectangular plane to fix the sand core in the upper box molding sand after mold lifting. The fixing device shall avoid the sprue and have less interference with the transverse sprue;
The core used to make the upper semicircular structure is semi cylindrical, and its diameter shall be less than the size of the casting semicircular structure, leaving a machining allowance of 3mm.
The middle of the rectangular longitudinal section of the semi-cylindrical shall be equipped with a fixing device to fix the core in the lower box molding sand after mold lifting.
Pouring position selection:
Considering that the main body of the casting is a hollow thin-wall structure, the gate is set above the center of the rectangular plane of the shaft support, and the liquid metal flows down evenly along the frame wall by setting a transverse gate.
The resin self hardening sand mold is used to maximize the graphitization expansion to realize the self feeding of castings;
The gating system is used as the main riser, and several air holes are pierced at the molding sand of the upper box.
The castings are small castings, which are directly molded in three boxes in a small sand box. After making the sprue, the mold is lifted, the core is installed and the transverse sprue is made, and then the box is closed for pouring.
- 3mm machining allowance shall be reserved for the large plane at the end and the upper parts of the two bosses;
- 3mm machining allowance shall be reserved in the direction of semicircular structure;
- Other parts are not required.
No cast hole:
Because the internal hollow structure of the casting can be cast through the installation of sand core, there is no need to design no casting hole on the mold.
Formwork lifting slope:
The casting is a small casting. According to its dimensional parameters, the draft angle in the table shall be 2.20 °.
The casting is a small casting, and its casting shrinkage mode is to hinder shrinkage, and the casting shrinkage rate is 0.8% ~ 1.0%.