The die-casting mold’s side slider positioning and wedging device are core components that ensure the precise operation of the side core-pulling mechanism. Their design quality directly impacts the core’s positioning accuracy, the stability of the core-pulling motion, and the mold’s service life. The side slider must be precisely positioned during the core-pulling and resetting process to prevent displacement due to vibration or inertia. The wedging device, on the other hand, must withstand the lateral pressure of the molten metal during the die-casting process to prevent the slider from retreating and causing dimensional deviations in the casting. Therefore, the design of these two devices must balance positioning accuracy, structural strength, and ease of operation, ensuring the reliability of the side core-pulling mechanism.
The core function of the side slider positioning device is to secure the slider in position after core pulling and when returning to its original position. Common positioning methods include spring-ball positioning, dowel pin positioning, and stopper positioning. The spring-ball positioning system is simple, with a spring pushing a steel ball into a dowel groove on the slider to achieve positioning. It is suitable for applications with low core pulling forces and short strokes. The dowel groove depth is typically 0.5-1mm, and the steel ball diameter is 3-5mm. The spring preload should be moderate to ensure reliable positioning without hindering slider movement. The dowel pin positioning system uses a pneumatic or hydraulic cylinder to drive a dowel pin into the slider’s pin hole. It is suitable for long-stroke, high-precision core pulling mechanisms. The clearance between the dowel pin and the pin hole is 0.01-0.03mm, ensuring positioning accuracy within 0.02mm. The stopper positioning system uses a stopper fixed to the template to contact the step surface of the slider to achieve position control. It is suitable for heavy-duty sliders. The stopper must be made of hardened 45 steel (hardness 40-45HRC), and the contact area must be at least 80% of the slider step area to prevent localized wear.
The design of the positioning device must take into account the slider’s motion inertia and vibration. For high-speed core-pulling mechanisms (speeds > 50 mm/s), the positioning device must have a buffering function. Rubber pads or spring plates can be installed at the positioning contact points to reduce impact loads. The positioning point should be set close to the slider’s center of gravity or force center to avoid torque generated during positioning that may cause the slider to skew. For example, a long slider requires two symmetrical positioning devices, with a spacing of 2/3 the slider length. In addition, the positioning device must be easy to adjust. For example, the spring-steel ball positioning can adjust the spring preload with an adjusting screw, and the positioning pin positioning can adjust the positioning pin height with a shim to ensure that positioning accuracy is maintained even after mold wear.
The main function of the wedge clamping device is to lock the side slider during mold closing, resisting the lateral pressure of the molten metal on the core and preventing the slider from moving. Common wedge clamping devices include wedge blocks and wedge pins. The wedge block is the most widely used. Its working surface aligns with the slider’s bevel, and the bevel angle is typically 2°-3° greater than that of the guide post (e.g., 20° for the guide post and 22° for the wedge block), ensuring full compression of the slider during mold closing. The wedge block is typically made of Cr12MoV with a quenching hardness of 55-60 HRC. The contact area with the slider must be greater than 70% of the slider’s pressure-bearing area, and the contact surface roughness must be below Ra0.8μm to reduce wear caused by long-term friction. The wedge block must be securely fixed to the fixed die using bolts and dowel pins. The bolt strength grade must be at least 8.8, and the dowel pin-hole fit must be H7/m6.
The strength design of the wedge clamp must meet the requirements for withstanding the maximum lateral force. Lateral force Fside = P × A (P is the specific pressure of the molten metal, and A is the lateral projected area of the core). The wedge clamp strength verification formula is σ = Fside / (B × L) ≤ [σ], where B is the wedge clamp width, L is the contact length, and [σ] is the allowable stress of the material (1500 MPa for Cr12MoV). For example, for a lateral force of 50,000 N, a wedge clamp width of 50 mm, and a contact length of 80 mm, σ = 50,000 / (50 × 80) = 12.5 MPa, which is far below the allowable value and meets the strength requirements. For large molds, a modular wedge clamp can be used. This segmented design reduces machining complexity, while reinforcing ribs are provided between the segments to improve overall rigidity. A clearance of 0.03-0.05 mm should be maintained between the wedge clamp and the slider to prevent interference during mold closing while ensuring effective locking.
