The whole gating system adopts the form of variable cross-section, that is, the gating system gradually shrinks from the DC channel to the internal channel, so as to ensure that the zinc alloy liquid continuously fills the gating system and minimize the eddy current entrainment.
The gate area of the nozzle outlet is 10% larger than that of the outlet.
(1) straight run
1)直浇道断面收缩率在5% ~ 10%之间。
1) The reduction of sprue section is between 5% and 10%.
2) From the straight gate to the transverse gate, the cross-sectional area is reduced by 10% - 30%. When the turning radius r < 10 mm, it decreases by 30%; when r > 15 mm, it decreases by 10%. The larger the turning radius, the smaller the resistance and the smaller the pressure loss.
3) Design defects often appear in production. The problems are as follows: (1) the increase of the cross-sectional area of the DC channel results in the mixing of air and liquid metal, which increases the chance of porosity in the casting. Make liquid metal flow unstable.
Type 1: double DC channel.
Type 2: small casting pen point DC channel.
The connection between the flow channel and the inner flow channel is usually trapezoid cross-section with an angle of 10 ° ~ 45 °.
The runner section shape (geometry) shall be taken into account when designing the runner. For a given cross-sectional area of the runner, the selected geometry should have the minimum perimeter, because with the increase of the perimeter of the runner, the speed loss and temperature loss of the liquid metal increase, and the filling time increases, which is not conducive to filling.
(3) Triangle connection area design
The main function of triangle area is to divide a main channel into two tributaries, or fill a cavity, or fill several areas with a cavity. The geometry and size of the triangle area are well designed, which makes the cross-sectional area of the gate gradually reduce to the direction of liquid metal flow. The branches bend into an elliptical curve to reduce resistance. Using fillets to control the pressure loss in 10-20%; reducing the distance of liquid metal flowing through the triangle; reducing the amount of air trapped in the branch channel.
Cross section area of main river channel / cross section area of two tributaries = 1.3 ~ 1.5.
(4) Internal gate and buffer
When the runner part decreases gradually, the speed increases. In order to reduce the high-speed impact of the liquid metal on the end of the gate, a buffer is set to reduce the impact, while accepting the cold liquid metal and blocking the gas.
The above is a detailed introduction to the casting form of Shandong Aluminum alloy die casting. For more information, please click http://www.jnhjgs.cn