LPDC mold slider core pulling structure, design points and failure reasons
Sliding block core pulling is an important structure for expanding the forming ability of LPDC molds, which is used for lateral tilting of castings.
1、 Quantitative matching of slider stroke, locking force, and lateral clamping force
The effective stroke of the slider needs to have a safety margin of 3-5mm more than the depth of the reverse buckle to prevent core pulling from scratching the surface of the casting. For every 1mm increase in the depth of the reverse buckle, the lateral clamping force increases by about 12%. The hydraulic slider locking pressure is usually set at 60% -75% of the mold system pressure. If the locking force is insufficient, the aluminum liquid pressure will push the slider back during filling, resulting in burrs and a defect rate of over 30%. The sliding block has a clearance of 0.02-0.04mm on one side, which is too small and causes thermal expansion and jamming; The gap is too large, and the aluminum liquid enters the mating surface, biting the slider. The inclined angle of the slider is commonly 10 ° -15 °. If the angle is too small, the wedge self-locking and core pulling resistance will be high; If the angle is too large, the stability of the locking mode will decrease. When designing the core pulling structure, Xinfeng Machinery calculates the lateral thrust of the filling type and matches the specifications of the oil cylinder.
2、 Sliding block cooling and exhaust matching scheme
The slider belongs to an independent movable insert and also requires a cooling channel. If the slider's hot joint is not cooled, it is easy to stick to aluminum and deform at high temperatures. About 42% of the slider's early failure is due to lack of cooling. The parting surface of the slider must be independently arranged with exhaust grooves, and the reverse position is often the last filling area where gas is easy to accumulate. The exhaust depth is 0.08-0.15mm. The wear-resistant plate of the slider is made of high hardness wear-resistant steel to reduce repeated sliding wear. After the wear-resistant plate wears out, it can be replaced directly without the need for overall repair of the slider body.
3、 Differences in overseas customers' demands for core pulling structures
Southeast Asian customers try to avoid slider structures as much as possible, prefer to modify product reverse buttons, simplify molds, and reduce procurement and maintenance costs. The multi lateral installation of the North American car shell is reversed, and the product structure cannot be changed. The slider is a must-have and requires synchronous motion timing simulation. European customers require the slider to have a position sensor to confirm the signal of core pulling in place, and to interlock with the die-casting machine for safety to prevent mold collision. Middle Eastern construction machinery castings have large reverse dimensions and high lateral thrust, so priority should be given to increasing the specifications of the oil cylinder to ensure reliable mold locking.
4、 Typical Failure Modes of Long term Production of Sliding Blocks
Aluminum material enters the clearance between the sliding blocks, and after cooling, it locks the sliding blocks. The machine is stopped for disassembly and cleaning, and a single shutdown can take up to 1-2 hours. The wear-resistant plate has been worn for a long time, the clearance between the fittings has increased, the slider position has shifted, the reverse buckle size exceeds the tolerance, and the casting assembly has failed. Insufficient cooling of the slider, continuous high temperature, material thermal deformation, failure of inclined plane locking mold, periodic lateral flash.
5、 Long tail traffic layout ideas
Sliding blocks and core pulling belong to the category of complex structural design searches, and the target audience is mold designers. Keywords: LPDC mold slide core design, low pressure casting side under cut; Question class: How to calculate LPDC slide locking force; Comparison class: Angle lifter vs Hydraulic slide for LPDC die. Suitable for complex mold topics, undertaking non-standard structure mold opening consulting traffic.
6、 Common misconceptions in the industry
Misconception 1: The smaller the gap between the sliders, the less likely it is for aluminum to run away. After being heated and expanded, the gap disappears, causing direct jamming, mold collision, and damage to the mold. Misconception 2: The greater the clamping force, the safer it is. If the clamping force exceeds the standard and the inclined surface is under pressure for a long time, plastic deformation and loss of slider accuracy are likely to occur. Misconception 3: The slider does not require cooling. If the slider continues to stick to aluminum at high temperatures and deform, it is a high-frequency fault point.
FAQ
Q: Is the angle range commonly used for slider slopes? A: 10 ° -15 °, balance locking stability and core pulling resistance. Q: How much is recommended for slider coordination with unilateral clearance? A：0.02–0.04mm， Balancing smooth sliding and anti slip aluminum. Q: Why should there be a margin reserved for the slider stroke? A: Add 3-5mm to the depth of the reverse buckle to avoid scratching the reverse buckle surface of the casting. Q: What is the most common failure of sliders? A: Aluminum liquid enters the gap and bites, causing the wear position of the wear-resistant plate to shift. Q: Do European customers have additional requirements for sliders? A: Position signal sensor, and safety interlock anti-collision mold for die-casting machine. Q: Should shallow reverse buckle give priority to inclined top or hydraulic slider? A: Shallow reverse buckle with small travel priority inclined top, deep reverse buckle with large lateral force selected slider. Q: What is the depth control of the slider exhaust groove? A：0.08–0.15mm， The inverted position is prone to gas accumulation. Q: Do sliders need to be cooled? A: It is recommended to provide cooling for the hot section slider to avoid deformation caused by aluminum sticking at high temperatures.
