Difficulties in synchronous filling control of multiple cavities in differential pressure casting molds for wheel hubs | Balance of flow channels in aluminum casting molds
Unbalanced multi cavity flow channels in differential pressure casting molds for wheel hubs can cause fluctuations in batch casting yield of 46%, leading to concentrated outbreaks of single cavity defects.
The deviation of the cross-sectional area of the sprue in each cavity is greater than 7%, the distribution of aluminum liquid is uneven, and the filling time difference can reach up to 0.32s. Filling the cavity first is prone to gas entrapment.
When the channel angle R is less than 4mm, the flow resistance of the aluminum liquid increases sharply, and the local flow velocity increases by 65%, resulting in oxidation inclusion defects caused by turbulent flow.
If the position deviation of the diversion cone exceeds 1.5mm, the flow rate of the two channels will be unbalanced, and the probability of exceeding the tolerance of the wall thickness of the same side cavity casting will increase by 41%.
Multiple cavity molds share a cooling circuit, and the temperature of the distal cavity mold is 18 ℃ higher than that of the proximal end. The solidification timing cannot be synchronized, and the shrinkage point position changes randomly.
The surface roughness of the runner is greater than Ra1.6, the flow resistance of aluminum liquid increases, the adhesion rate of oxide scale increases by 34%, and the gate is blocked for a long time.
Differential pressure casting molds for wheel hubs are the preferred choice for expanding production in head hub factories. Compared with gravity casting molds, low-pressure die-casting molds (LPDC), counter pressure casting molds (CPC), motorcycle wheel hub casting molds, and low-pressure casting molds for wheel hubs are more suitable for batch stable production. They cover different process routes. Structural casting molds, aluminum alloy wheel hub molds, aluminum casting forming molds, low-pressure casting tooling molds, and multi cavity solutions are commonly used for cost reduction and efficiency improvement of small and medium-sized wheel hubs. Zhejiang Xinfeng Machinery has recorded the trial of multi cavity differential pressure molds, and the adjustment of flow channel balance accounts for 52% of the total trial time. Many molds have not undergone flow channel simulation in the early stage and rely on on-site polishing and trial and error to extend the delivery cycle. Many customers blindly increase the number of cavities in order to improve single-mode output. For differential pressure molds with more than 4 cavities, the difficulty of balancing and debugging the flow channel increases exponentially, and the overall yield rate decreases by 9%. Channel balance can be divided into geometric balance and dynamic balance. Simple dimensional symmetry cannot offset the differences in heat dissipation, and a differentiated cooling scheme is required. Many overseas purchasers will require two cavities for the first mock examination or four cavities for the first mock examination, so as to reduce the mold opening and closing cycle cost shared by a single casting. Mexican auto parts customers have the most stringent requirements for multi cavity consistency. Excess material accumulation in the flow channel requires the installation of a slag collection bag, with a volume not less than 11% of the total flow channel volume, to capture cold materials and oxidized slag in the early stage. The differential pressure process relies on the slow pushing of aluminum liquid through pressure difference, and the flow channel design cannot simply copy the high-pressure die-casting diversion scheme. The priority of flow rate control is higher than that of charging. In the B2B platform RFQ, the unit price of multi cavity differential pressure molds has increased by 55% compared to single cavity molds. The customer base has sufficient budget, and the technical communication cycle is longer, making it suitable for technical content drainage.
FAQ
1. Question: What is the upper limit for controlling the cross-sectional area deviation of multi cavity sprues?
Answer: The deviation of the cross-sectional area of each cavity runner should be controlled within 7% as much as possible.
2. Question: What is the recommended rounded corner R value for the minimum channel angle?
Answer: The channel angle R should not be less than 4mm to reduce the risk of turbulence in aluminum liquid.
3. Question: What is the minimum reference ratio for the volume of the slag collection bag?
Answer: The volume of the slag collection bag shall not be less than 11% of the volume of the supporting flow channel.
4. Question: What is the change trend of good products of the first mock examination four cavity differential pressure mold?
Answer: After 4 cavities, the difficulty of debugging increases, and the yield tends to decline.
5. Question: What are the recommended standards for surface roughness of flow channels?
Answer: The roughness of the inner wall of the flow channel should be controlled within Ra1.6 to reduce slag accumulation.
6. Question: What is the allowable range of temperature difference for multi cavity molds?
Answer: It is recommended to control the temperature difference of each cavity mold within 18 ℃.
