A method and system for partial extrusion compression of a mold for a motorcycle accessory

Abstract

The application discloses a kind of mould local extrusion supplementing methods and systems of motorcycle accessories, it is related to metal die casting forming technical field, comprising: using casting simulation software determines supplement target position and selects corresponding driving sleeve type pressurizing structure;After injection, wait according to extrusion delay time determined based on temperature field;Control external hydraulic source to supply oil to sealed hydraulic cavity and promote sleeve type pressurizing structure to supplement target position Apply boost pressure;After advancing to preset stroke, pressure is maintained and unloading retreats to original position.The application realizes the accurate control of supplement position and extrusion opportunity, effectively eliminates local thick part shrinkage hole defect, and improves casting quality.

Description

Technical Field

[0001] This invention relates to the field of metal die casting technology, specifically to a method and system for local extrusion and shrinkage compensation in the molds of motorcycle parts. Background Technology

[0002] In the die-casting production of motorcycle parts (such as engine lower cylinder blocks and crankcases), due to the complex structure and uneven wall thickness of the castings, localized thicker areas are prone to forming hot spots, resulting in shrinkage cavities and porosity defects. Existing technologies typically use extrusion pins within the mold for localized shrinkage compensation, but this method has the following problems: First, the extrusion pin position is fixed, making it difficult to flexibly adjust the compensation area based on the predicted shrinkage cavity location for different castings or different batches of the same casting; second, the timing of extrusion initiation relies heavily on experience, making it difficult to accurately match the semi-solid state of the molten metal, leading to compensation failure; third, the extrusion pin is prone to jamming at high temperatures, and there is a lack of effective real-time monitoring and anti-jamming mechanisms, resulting in high maintenance costs. Therefore, there is an urgent need for a mold-based local extrusion compensation method and system that can flexibly select the compensation area based on the predicted shrinkage cavity location, precisely control the extrusion timing, and has safety monitoring functions. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art. This invention provides a method and system for local extrusion and shrinkage compensation of motorcycle parts. By setting a sleeve-type pressure structure in the mold, and based on solidification simulation for precise point selection and shrinkage compensation, adaptive delay control and real-time status monitoring, efficient and high-quality molding processing of motorcycle parts can be achieved.

[0004] This invention provides a method for partial extrusion and shrinkage compensation in the mold of motorcycle parts, comprising the following steps: The solidification process of motorcycle parts was numerically simulated using casting simulation software. Based on the simulation results, the area where the temperature field was in the solid-liquid coexistence range and the area that was finally solidified was determined as the feeding target location. Based on the corresponding area of ​​the feeding target location on the mold cavity, the corresponding driven sleeve-type pressure structure in the upper mold body was determined. After the mold is closed, the molten metal is injected into the mold cavity under high pressure to complete the filling. After the die casting machine finishes the injection action, it outputs an injection end signal to the PLC controller. After receiving the injection end signal, the PLC controller starts timing and waits for the preset extrusion delay time. This extrusion delay time is determined based on the time required for the temperature field at the target location to drop to the solid-liquid coexistence temperature range in the simulation results. After the extrusion delay time is reached, the PLC controller controls the external hydraulic source to supply oil to the oil passage inside the mold. The hydraulic oil enters the sealed hydraulic cavity between the sleeve-type pressurizing structure and the upper mold body, pushing the sleeve-type pressurizing structure to move towards the lower mold body. The extrusion end face of the sleeve-type pressurizing structure directly applies pressurizing pressure to the molten metal at the feeding target position. After the sleeve-type pressurizing structure advances to the preset stroke, the PLC controller controls the hydraulic source to maintain pressure, and then the PLC controller controls the hydraulic source to unload, and the sleeve-type pressurizing structure returns to its original position.

[0005] Furthermore, the solidification process of the motorcycle parts is numerically simulated using casting simulation software. Based on the simulation results, the region where the temperature field is in the solid-liquid coexistence range and is the last to solidify is determined as the feeding target location. The corresponding driven sleeve-type pressurization structure in the upper mold body is determined based on the corresponding region of the feeding target location on the mold cavity. The predicted volume and location coordinates of shrinkage cavities and porosity in each region during the solidification process were obtained using casting simulation software. The compensation coverage area of ​​each sleeve-type pressurizing structure is established with the axial position of each sleeve-type pressurizing structure as the center and the effective compensation radius of the sleeve-type pressurizing structure as the radius; Spatially superimpose and compare the shrinkage and loosening prediction locations of each shrinkage coverage area with the shrinkage and loosening prediction locations of each area, and select one or more sleeve-type pressurization structures with the shortest distance between the center of the shrinkage coverage area and the shrinkage and loosening prediction location as the driving object. The PLC controller controls an external hydraulic source to synchronously supply oil to the oil passages of the selected sleeve-type pressurization structure.

[0006] Furthermore, the step of spatially superimposing and comparing each feeding coverage area with the predicted shrinkage and porosity location of each area, and selecting one or more sleeve-type pressurization structures with the shortest distance between the center of the feeding coverage area and the predicted shrinkage and porosity location as the driving object includes: A two-dimensional domain of action for each sleeve-type pressurization structure is established with the center of the compensation coverage area as the origin and the outer boundary of the compensation coverage area as the effective boundary. Project the spatial coordinates of the predicted shrinkage and porosity positions onto the two-dimensional action plane, and determine one by one whether the projection point of each predicted shrinkage and porosity position falls within the two-dimensional action area of ​​each sleeve-type pressurization structure. When the projection point of the same shrinkage and loosening prediction position falls into the two-dimensional action domain of multiple sleeve-type pressurizing structures at the same time, the distance between the projection point and the center of the compensation coverage area of ​​each sleeve-type pressurizing structure is calculated, and the sleeve-type pressurizing structure with the smallest distance is selected as the corresponding driving object of the shrinkage and loosening prediction position.

[0007] Furthermore, the establishment of the compensation coverage area of ​​each sleeve-type pressurizing structure, centered on the axial position of each sleeve-type pressurizing structure and with the effective compensation radius of the sleeve-type pressurizing structure as the radius, includes: The pressure transmission attenuation curves of each sleeve-type pressurizing structure under different extrusion strokes were obtained by casting simulation software. Taking the center of the extrusion end face as the starting point and the critical position where the pressure transmission attenuates to the point where it is insufficient to drive the flow of molten metal as the boundary, the initial value of the effective feeding radius of each sleeve-type pressurizing structure was determined. For each determined initial effective shrinkage radius, the radius is gradually reduced and enlarged proportionally to form multiple radius candidate values. For each radius candidate value, the shrinkage coverage area corresponding to the shrinkage hole and loosening prediction position is re-executed. The number of shrinkage hole and loosening prediction positions falling into the corresponding shrinkage coverage area under each radius candidate value is counted. The minimum value among the radius candidate values ​​whose coverage number meets the preset threshold is taken as the final effective shrinkage radius.

[0008] Furthermore, the method for determining the preset itinerary includes the following steps: The volume of the hot spot that needs to be compensated is obtained from the 3D model of the motorcycle parts; Multiply the volume of the hot spot by the solidification volume shrinkage rate of the alloy used in the component to obtain the theoretical shrinkage compensation volume; Divide the theoretical compensation volume by the extrusion end face area of ​​the sleeve-type pressure structure and multiply by the safety factor to obtain the preset stroke value.

[0009] Furthermore, obtaining the volume of the hot spot area requiring shrinkage based on the 3D model of the motorcycle parts includes: Temperature field data and solid fraction data of each grid cell at the hot spot of motorcycle parts were obtained by casting simulation software during the solidification process. Using a solid fraction of 90% as the solidification cutoff condition, multiple temperature gradient layers with solid fractions gradually increasing from the extrusion end face of the sleeve-type pressurized structure towards the center of the hot spot were extracted from the temperature field of the hot spot. Calculate the solidification shrinkage volume corresponding to each temperature gradient layer. For these multiple temperature gradient layers, accumulate the solidification shrinkage volume sequentially from the extrusion end face to the center of the hot spot. After each layer is accumulated, calculate the difference between the current accumulated value and the theoretical compensation volume. When the difference is in a stable state, configure the corresponding accumulated value as the volume of the hot spot that needs compensation.

[0010] The present invention also provides a local extrusion and shrinkage compensation system for a mold of motorcycle parts. The shrinkage compensation system is used to execute the shrinkage compensation method and includes an upper mold body, a lower mold body, multiple sleeve-type pressurizing structures, a PLC controller and multiple solenoid directional valves. The upper mold body has multiple mounting through holes in the middle that extend from the back to the cavity surface. These mounting through holes are arranged in an array on the upper mold body and each corresponds to a different area of ​​the mold cavity. Each sleeve-type pressure structure is slidably installed in each mounting through hole. The upper end of each sleeve-type pressure structure and the upper end wall of the corresponding mounting through hole form a closed hydraulic cavity. Multiple independent oil passages are opened inside the upper mold body. One end of each oil passage is connected to each closed hydraulic cavity, and the other end extends to the back of the upper mold body and is provided with an independent oil passage interface. The lower end face of each sleeve-type pressure structure forms an extrusion end face at the cavity surface of the upper mold body. An external hydraulic power source is connected to each oil circuit interface through oil pipes. Each oil circuit interface is equipped with an independent solenoid directional valve on the pipeline between it and the external hydraulic power source. The signal input terminal of the PLC controller is connected to the injection end signal output terminal of the die casting machine. Each control output terminal of the PLC controller is connected to the signal input terminal of each solenoid directional valve. The inlet and outlet ports of each electromagnetic directional valve are connected to the outlet and return lines of an external hydraulic power source, respectively. The working ports of each electromagnetic directional valve are connected to the corresponding oil circuit interfaces on the back of the upper mold body via oil pipes.

[0011] Furthermore, the length of the guide section of each sleeve-type pressurizing structure is greater than the length of the guide hole section of the corresponding mounting through hole. When the sleeve-type pressurizing structure is in the retracted position, the guide section is located inside the guide hole section of the mounting through hole and slides with the inner wall of the guide hole section. The lower end face of the sleeve-type pressurizing structure is flush with the cavity surface of the upper mold body.

[0012] Furthermore, an oil distribution block is fixed on the back of the upper mold body, and each oil circuit interface is centrally located on the oil distribution block. The oil distribution block has internal oil channels that correspond one-to-one with each oil circuit interface. One end of each internal oil channel is connected to the corresponding oil circuit interface, and the other end extends to the side of the oil distribution block and is provided with a pipe joint.

[0013] Furthermore, a sliding bearing is provided between the side wall of each sleeve-type pressurizing structure and the inner wall of the guide hole of the corresponding mounting through hole, and the sleeve-type pressurizing structure slides in cooperation with the inner wall of the guide hole through the sliding bearing.

[0014] This invention provides a method and system for local extrusion and shrinkage compensation in the mold of motorcycle parts. By numerically simulating the solidification process using casting simulation software, the final solidification region in the solid-liquid coexistence temperature field is accurately identified as the shrinkage compensation target. Based on a spatial superposition comparison algorithm, the nearest sleeve-type pressure structure is automatically selected as the driving object. This eliminates the shrinkage compensation blind zone caused by the positional deviation of the traditional fixed extrusion pin, significantly improving the accuracy of the shrinkage compensation position and thus improving the molding quality of motorcycle parts. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a flowchart of the mold local extrusion and shrinkage control method according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of a motorcycle parts partial extrusion and shrinkage compensation mold according to an embodiment of the present invention; Figure 3 This is a cross-sectional view of the motorcycle parts mold partial extrusion and shrinkage compensation system according to an embodiment of the present invention; Figure 4 This is an exploded view of the partial extrusion and shrinkage compensation system for motorcycle parts molds according to an embodiment of the present invention. Detailed Implementation

[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] Example 1: like Figure 1 As shown, this embodiment provides a method for localized extrusion and shrinkage compensation in the mold of motorcycle parts. This method solves the shrinkage cavity defect problem in locally thick areas of complex castings by precisely controlling the timing and position of extrusion. The shrinkage compensation method mainly includes the following steps: Step S1 involves using casting simulation software to numerically simulate the solidification process of motorcycle parts. Based on the simulation results, the region where the temperature field is within the solid-liquid coexistence range and is the last to solidify is identified as the feeding target location. The corresponding driving sleeve-type pressure structure in the upper mold body is then determined based on the corresponding region on the mold cavity. Specifically, during the mold design and process debugging phase, casting simulation software such as ProCAST and MagmaSoft is used to perform filling and solidification simulation analysis on specific motorcycle parts (such as engine lower cylinder blocks and crankcases). Due to uneven casting wall thickness and slow cooling rates in thicker areas, these areas often become hot spots for final solidification and are also high-risk areas for shrinkage cavities and porosity defects. The simulation software can predict the specific three-dimensional coordinates and volume of these defects. In this embodiment, the region where the temperature field is within the solid-liquid coexistence range and is the last to solidify is identified as the key target point requiring external intervention for feeding. Simultaneously, based on multiple pre-arrayed sleeve-type pressurizing structures on the mold, a mapping relationship between simulated spatial coordinates and physical actuators is established, thereby selecting the sleeve-type pressurizing structure that can effectively cover the compensation target position as the execution unit for subsequent actions. This point selection method based on digital simulation significantly improves the accuracy of the compensation position compared to the traditional point-fixing method that relies on experience and trial and error.

[0019] Step S2: After the mold is closed, molten metal is injected into the mold cavity under high pressure to complete the filling. After the die-casting machine finishes the injection action, it outputs an injection end signal to the PLC controller. Specifically, after the die-casting machine closes and locks the mold, the injection punch pushes the molten metal at high speed to fill the cavity. When the injection stroke reaches the set end point or the pressurization stage begins, the die-casting machine control system generates an electrical signal (i.e., the injection end signal) and transmits it to the PLC controller in real time. This signal marks the end of the filling process and the beginning of the solidification and cooling process. It is the reference zero point for the entire local extrusion and feeding timing control, ensuring that subsequent delays and extrusion actions are strictly synchronized with the actual solidification state of the casting.

[0020] In step S3, after receiving the injection end signal, the PLC controller starts timing and waits for the preset extrusion delay time. This extrusion delay time is determined based on the time required for the temperature field at the target location to drop to the solid-liquid coexistence temperature range as shown in the simulation results. This is the core control link for achieving precise extrusion in this embodiment. The extrusion delay time is not a fixed empirical value, but a dynamic parameter directly bound to the thermodynamic evolution law of the target location. From a microscopic perspective, the solidification of molten metal is a process from liquid to solid-liquid coexistence (pasty region) and then to complete solidification. If extrusion is performed too early while the molten metal is still in a fully liquid state, the pressure cannot be effectively transmitted and it is easy to cause molten metal to splash or flash; if extrusion is performed after the molten metal has completely solidified, the dendrite skeleton has formed a rigid connection, and external force cannot deform it to fill the shrinkage gaps. Therefore, only when the temperature at the target location drops exactly to the solid-liquid coexistence temperature range does the molten metal have the best plastic flow characteristics, and only then can the pressure applied be most effectively used to compact the dendrite gaps and eliminate shrinkage porosity. By simulating the arrival time of the temperature window and converting it into a delay parameter that can be executed by the PLC, the extrusion action is fundamentally guaranteed to occur within the optimal process window.

[0021] In step S4, after the extrusion delay time is reached, the PLC controller controls the external hydraulic source to supply oil to the oil passage inside the mold. The hydraulic oil enters the sealed hydraulic cavity between the sleeve-type pressure structure and the upper mold body, pushing the sleeve-type pressure structure to move towards the lower mold body. The extrusion end face of the sleeve-type pressure structure directly applies pressure boosting to the molten metal at the target shrinkage location. Specifically, when the timer reaches the preset extrusion delay time, the PLC controller issues a command to open the corresponding solenoid reversing valve, and high-pressure hydraulic oil is injected into the sealed hydraulic cavity through the independent oil passage inside the upper mold body. Driven by hydraulic force, the sleeve-type pressure structure moves downward along the axial direction, and its bottom extrusion end face passes through the cavity surface, directly embedding and compressing the molten metal in a semi-solid state. This "direct contact" pressure application structure avoids the pressure attenuation problem caused by the force transmission through an intermediate medium in traditional extrusion pins, ensuring that the boosting pressure can act on the core area of ​​the hot spot without damage, forcing the solute-rich liquid metal to fill the tiny pores caused by solidification shrinkage.

[0022] In step S5, after the sleeve-type pressurizing structure advances to the preset stroke, the PLC controller controls the hydraulic source to maintain pressure. Subsequently, the PLC controller controls the hydraulic source to unload, and the sleeve-type pressurizing structure returns to its original position. Specifically, when the sleeve-type pressurizing structure descends to the pre-calculated end of the stroke, the system switches to the pressure-holding state, maintaining a constant pressure for a period of time to ensure stable feeding effect and prevent molten metal backflow. After the pressure holding period ends, the PLC controller controls the reversing valve to switch to the return oil position, the hydraulic chamber is depressurized, and the sleeve-type pressurizing structure retracts upward under the action of the return spring or return cylinder until its extrusion end face is flush with the upper mold cavity surface again, completing a complete feeding cycle and preparing for the next die-casting production. Through the above-mentioned main logic of "simulated positioning - delay waiting - hydraulic extrusion - pressure holding and retraction", this embodiment constructs a closed-loop local extrusion feeding control method, providing a basic execution framework for more refined point selection algorithms, safety monitoring, and stroke calculation in subsequent embodiments.

[0023] Specifically, in step S1, casting simulation software is used to numerically simulate the solidification process of motorcycle parts. Based on the simulation results, the area where the temperature field is in the solid-liquid coexistence range and the area that is finally solidified is determined as the feeding target position. The process of determining the corresponding driven sleeve-type pressure structure in the upper mold body based on the corresponding area of ​​the feeding target position on the mold cavity includes the following sub-steps.

[0024] The predicted volume and location coordinates of shrinkage cavities and porosity in various regions during solidification are obtained through casting simulation software. For example, using simulation platforms such as ProCAST or MagmaSoft, the three-dimensional model of the casting, alloy thermophysical parameters, and mold boundary conditions are input to calculate the three-dimensional spatial distribution data of defects that may occur due to insufficient feeding at the end of solidification. This data includes not only the center coordinates of the defects but also the predicted volume of the defects, providing a data foundation for subsequent quantitative matching.

[0025] The feeding coverage area of ​​each sleeve-type pressurizing structure is established with its axial position as the center and its effective feeding radius as the radius. The effective feeding radius refers to the maximum range within which the sleeve-type pressurizing structure can effectively transmit pressure and eliminate shrinkage under specific process conditions. This parameter is not a fixed geometric dimension but a dynamic process parameter related to factors such as alloy type, extrusion pressure, and the semi-solid rheological properties of the molten metal. For example, for the highly fluid aluminum alloy ADC12, a larger effective feeding radius can be taken under higher extrusion pressures; while for magnesium alloys or low-pressure conditions, the value needs to be reduced accordingly. By transforming discrete physical execution units into continuous mathematical coverage areas, a mapping between hardware capabilities and software models is achieved.

[0026] The system spatially overlays and compares the coverage areas of each feeding region with the predicted locations of shrinkage cavities and porosity in each region, selecting one or more sleeve-type pressurizing structures with the shortest distance between the center of the feeding coverage area and the predicted location of shrinkage cavities and porosity as the driving object. Specifically, the system automatically calculates which sleeve-type pressurizing structures' feeding coverage areas each predicted shrinkage point falls into. If a predicted point is included by multiple coverage areas, the sleeve-type pressurizing structure with the smallest center-to-center distance is selected first. The physical significance of adopting the "shortest distance" principle is that extrusion feeding essentially fills gaps by forcing the flow of molten metal. The shorter the flow path, the smaller the pressure loss along the way, the higher the effective pressure ratio reaching the hot spot core, and the more reliable the feeding effect. At the same time, applying pressure at close range can also reduce disturbance to the surrounding solidified areas and reduce the risk of generating new defects. If a predicted shrinkage point is not included by any coverage area, the system can output an early warning prompt to adjust the mold design or increase the number of pressurizing units.

[0027] The PLC controller controls an external hydraulic source to synchronously supply oil to the oil circuit channels of the selected sleeve-type pressurizing structure. When there are multiple shrinkage prediction points corresponding to different sleeve-type pressurizing structures, the PLC controller can simultaneously activate multiple solenoid directional valves to achieve multi-point parallel shrinkage compensation. If multiple prediction points correspond to the same sleeve-type pressurizing structure, that structure only needs to operate once to cover multiple defect risk areas. This on-demand allocation and synchronous execution strategy significantly improves production efficiency and energy utilization compared to traditional full-array blind operation or single-point sequential operation methods.

[0028] Specifically, the step of spatially superimposing and comparing each feeding coverage area with the predicted location of shrinkage orifice and porosity in each area, and selecting one or more sleeve-type pressurization structures with the shortest distance between the center of the feeding coverage area and the predicted location of shrinkage orifice and porosity as the driving object includes: A two-dimensional domain of action for each sleeve-type pressurization structure is established with the center of the compensation coverage area as the origin and the outer boundary of the compensation coverage area as the effective boundary. Project the spatial coordinates of the predicted shrinkage and porosity positions onto the two-dimensional action plane, and determine one by one whether the projection point of each predicted shrinkage and porosity position falls within the two-dimensional action area of ​​each sleeve-type pressurization structure. When the projection point of the same shrinkage and loosening prediction position falls into the two-dimensional action domain of multiple sleeve-type pressurizing structures at the same time, the distance between the projection point and the center of the compensation coverage area of ​​each sleeve-type pressurizing structure is calculated, and the sleeve-type pressurizing structure with the smallest distance is selected as the corresponding driving object of the shrinkage and loosening prediction position.

[0029] Using the center of the shrinkage coverage area of ​​each sleeve-type pressurizing structure as the origin and the outer boundary of the shrinkage coverage area as the effective action boundary, a two-dimensional action domain is established on the cavity surface for each sleeve-type pressurizing structure. The spatial coordinates of the predicted shrinkage cavity and porosity position are projected onto the plane of this two-dimensional action domain along a direction perpendicular to the cavity surface to obtain the coordinates of the projection points of each predicted shrinkage cavity and porosity position. Then, it is determined whether each projection point falls within the two-dimensional action domain of each sleeve-type pressurizing structure: if the projection point is within the boundary range of the two-dimensional action domain, it is determined that the sleeve-type pressurizing structure has a shrinkage compensation effect on the predicted shrinkage cavity and porosity position; if the projection point is outside the two-dimensional action domain, it is determined that it does not have a shrinkage compensation effect. When the projection point of the same predicted shrinkage cavity and porosity position falls within the two-dimensional action domain of multiple sleeve-type pressurizing structures, the Euclidean distance from the projection point to the center of the shrinkage coverage area of ​​each sleeve-type pressurizing structure is calculated, and the sleeve-type pressurizing structure with the smallest distance is selected as the final corresponding driving object for the predicted shrinkage cavity and porosity position.

[0030] Furthermore, in this embodiment, a certain hole shrinkage prediction position falls within the two-dimensional action domain of three sleeve-type pressurizing structures. After calculation, the center distance between it and the second sleeve-type pressurizing structure is the shortest. Therefore, the second sleeve-type pressurizing structure is selected as the driving object for the hole shrinkage prediction position.

[0031] By establishing a two-dimensional domain and projecting the predicted position of the shrinkage cavity onto this plane for judgment, the problem of position comparison in three-dimensional space is simplified to the judgment of point domain relationships in a two-dimensional plane, reducing computational complexity. When the same predicted position of the shrinkage cavity falls into the two-dimensional domain of multiple sleeve-type pressurizing structures, the minimum distance is used as the selection criterion to determine the unique corresponding driving object. This avoids excessive shrinkage caused by repeated driving of the same shrinkage cavity position by multiple sleeve-type pressurizing structures, and also avoids interference between multiple sleeve-type pressurizing structures when they act simultaneously.

[0032] Specifically, the establishment of the compensation coverage area of ​​each sleeve-type pressurizing structure, centered on the axial position of each sleeve-type pressurizing structure and with the effective compensation radius of the sleeve-type pressurizing structure as the radius, includes: The pressure transmission attenuation curves of each sleeve-type pressurizing structure under different extrusion strokes were obtained by casting simulation software. Taking the center of the extrusion end face as the starting point and the critical position where the pressure transmission attenuates to the point where it is insufficient to drive the flow of molten metal as the boundary, the initial value of the effective feeding radius of each sleeve-type pressurizing structure was determined. For each determined initial effective shrinkage radius, the radius is gradually reduced and enlarged proportionally to form multiple radius candidate values. For each radius candidate value, the shrinkage hole and loosening prediction position is re-judged for the shrinkage coverage area. The number of shrinkage hole and loosening prediction positions falling into the corresponding shrinkage coverage area under each radius candidate value is counted. The minimum value among the radius candidate values ​​whose coverage number meets the preset threshold is taken as the final effective shrinkage radius.

[0033] Before establishing the feeding coverage area for each sleeve-type pressurizing structure, the pressure transmission attenuation curves of each sleeve-type pressurizing structure under different extrusion strokes are first obtained using ProCAST casting simulation software. Specifically, different extrusion strokes of 1mm, 2mm, 3mm, 4mm, and 5mm are set in the simulation software, and the pressure values ​​transmitted from the center of the extrusion end face to the surrounding molten metal are recorded under each condition. The critical pressure value (10% of the casting pressure in this embodiment) at which the pressure transmission attenuates to a level insufficient to drive the flow of molten metal is taken as the critical position, and the distance from the center of the extrusion end face to this critical position is determined as the initial value of the effective feeding radius under the extrusion stroke condition. Then, this initial value of the effective feeding radius is gradually reduced and increased by a factor of 0.7, 0.8, 0.9, 1.1, 1.2, and 1.3 to form multiple radius candidate values. The falling-in judgment of the shrinkage cavity and porosity prediction positions is re-executed for the feeding coverage area corresponding to each radius candidate value, and the number of shrinkage cavity and porosity prediction positions falling into the corresponding feeding coverage area under each radius candidate value is counted. The minimum value among the candidate radii that meet the preset threshold (in this embodiment, the preset threshold is 80% of the total number of predicted hole locations) is taken as the final effective shrinkage radius. In this embodiment, the initial effective shrinkage radius is 6mm. After scaling verification, the coverage reaches the preset threshold when the radius is 5.4mm (0.9 times). Therefore, 5.4mm is taken as the final effective shrinkage radius.

[0034] The initial value of the effective compensation radius is determined by simulating the pressure transmission attenuation curve. This initial value is then verified and corrected using scaling validation. Finally, the minimum value among candidate values ​​that meet a preset threshold for coverage quantity is taken as the effective compensation radius. This transforms the boundary definition of the compensation coverage area from empirical estimation to quantitative verification based on simulation data. A radius that is too large may lead to overly lenient judgment of the compensation coverage area, potentially selecting sleeve-type pressurization structures with insufficient actual compensation effect. Conversely, a radius that is too small may miss some predicted orifice locations, resulting in the corresponding sleeve-type pressurization structures not being selected and thus not receiving compensation. This verification method ensures that the effective compensation radius is as accurate as possible while guaranteeing sufficient coverage of orifice locations, improving the objectivity and accuracy of establishing the compensation coverage area.

[0035] Furthermore, before the sleeve-type pressurizing structure advances to the preset stroke in step S4, the preset stroke is determined by the following steps.

[0036] The volume of the hot spot requiring shrinkage is obtained from the 3D model of the motorcycle parts. This volume can be extracted directly from casting simulation software or obtained through geometric measurements of the abrupt wall thickness change area using CAD software.

[0037] Specifically, obtaining the volume of the hot spot area requiring shrinkage based on the 3D model of the motorcycle parts includes: Temperature field data and solid fraction data of each grid cell at the hot spot of motorcycle parts were obtained by casting simulation software during the solidification process. Using a solid fraction of 90% as the solidification cutoff condition, multiple temperature gradient layers with solid fractions gradually increasing from the extrusion end face of the sleeve-type pressurized structure towards the center of the hot spot were extracted from the temperature field of the hot spot. Calculate the solidification shrinkage volume corresponding to each temperature gradient layer. For the multiple temperature gradient layers, accumulate the solidification shrinkage volume sequentially from the extrusion end face to the center of the hot spot. After each layer is accumulated, calculate the difference between the current accumulated value and the theoretical compensation volume. When the difference no longer changes or begins to increase, use the accumulated value when the difference no longer changes as the volume of the hot spot that needs compensation.

[0038] Specifically, the temperature field data and solids fraction data of each grid cell in the hot spot region of the lower cylinder block of a motorcycle engine were obtained using ProCAST casting simulation software during the solidification process. Using a solids fraction of 90% as the solidification cutoff condition, multiple temperature gradient layers were extracted from the temperature field of the hot spot region, showing a progressively increasing solids fraction from the extrusion end face of the sleeve-type pressurized structure towards the center of the hot spot. In this embodiment, a total of 5 temperature gradient layers were extracted from the extrusion end face to the center of the hot spot, with solids fraction ranges of 0~20%, 20%~40%, 40%~60%, 60%~80%, and 80%~90%, respectively. The solidification shrinkage volume corresponding to each temperature gradient layer was calculated. In this embodiment, the solidification shrinkage volumes corresponding to each layer were 2.1 mm³, 1.8 mm³, 1.5 mm³, 1.0 mm³, and 0.6 mm³, respectively. The solidification shrinkage volume of each layer is accumulated sequentially from the extrusion end face to the center of the hot spot: After adding the first layer, the accumulated value is 2.1 mm³, which is 4.45 mm³ different from the theoretical shrinkage requirement of 6.55 mm³; after adding the second layer, the accumulated value is 3.9 mm³, with a difference of 2.65 mm³; after adding the third layer, the accumulated value is 5.4 mm³, with a difference of 1.15 mm³; after adding the fourth layer, the accumulated value is 6.4 mm³, with a difference of 0.15 mm³; after adding the fifth layer, the accumulated value is 7.0 mm³, and the difference becomes -0.45 mm³, meaning that the accumulated value has exceeded the theoretical shrinkage requirement. When accumulating to the fourth layer, the difference of 0.15 mm³ no longer changes and is a positive value, so the accumulated value of 6.4 mm³ for the fourth layer is taken as the volume of the hot spot area that needs shrinkage.

[0039] Traditional methods directly treat the entire volume of the hot spot as the object of shrinkage calculation. However, in the central region of the hot spot, the shrinkage channel is interrupted in the later stage of solidification, and the molten metal has lost its fluidity. The shrinkage in this area cannot be compensated by the advancement of the extrusion end face. Directly including the entire area in the shrinkage calculation will lead to an overestimation of the stroke. If the extrusion end face continues to advance beyond the actual shrinkage boundary, it will over-extrude the solidified metal, causing flash or even mold damage. This embodiment uses a layered accumulation method of solid fraction, with the difference no longer changing as the cutoff condition. It excludes the temperature gradient layer far from the extrusion end face and where the shrinkage channel is interrupted from the shrinkage calculation range, and only includes the shrinkage volume of the gradient layer with unobstructed shrinkage channels in the calculation. This makes the determination of the stroke match the actual shrinkage physical process and avoids over-extrusion.

[0040] Multiplying the volume of the hot spot by the solidification volume shrinkage rate of the alloy used in the component yields the theoretical shrinkage compensation volume. Solidification volume shrinkage rate is an inherent thermophysical property of alloy materials, representing the proportion of volume reduction per unit volume of liquid metal during complete solidification. For example, the typical solidification volume shrinkage rate of ADC12 aluminum alloy is approximately 6% to 7%, and that of AZ91D magnesium alloy is approximately 4% to 5%. The theoretical shrinkage compensation volume is the additional volume of molten metal required to compensate for this natural shrinkage.

[0041] Dividing the theoretical compensation volume by the extrusion end face area of ​​the sleeve-type pressure structure and multiplying by a safety factor yields the preset stroke value. This calculation model can be expressed by the following formula: ; in, This indicates the preset stroke value, which is the axial distance that the extrusion end face of the sleeve-type pressurizing structure needs to move downward. Indicates the volume of the hot spot; Indicates the solidification volume shrinkage rate of an alloy; This represents the area of ​​the extrusion end face of the sleeve-type pressure structure; This represents the safety factor.

[0042] Regarding safety factor The physical meaning of the safety factor is primarily used to compensate for various non-theoretical factors that deviate from ideal conditions in actual working situations. These include: the viscous flow resistance of molten metal flowing through the dendritic skeleton in a semi-solid state, frictional losses between the extrusion end face and the cavity wall, elastic deformation and leakage of the hydraulic system, and deviations between simulated predictions and actual solidification behavior. If the stroke is calculated solely based on the theoretical feeding volume, the actual feeding amount is often insufficient due to the aforementioned losses, and shrinkage defects cannot be completely eliminated. Therefore, the safety factor... Values ​​greater than 1 are typically chosen, such as 1.2 to 1.5. Specific values ​​can be calibrated based on alloy flowability, mold complexity, and historical production data. By introducing a safety factor, purely theoretical geometric calculations are transformed into robust control parameters adapted to engineering practice, ensuring the stability and reliability of the feeding effect under different batches and environmental conditions.

[0043] Specifically, in step S4, after the PLC controller controls the external hydraulic source to supply oil to the oil passage of the selected sleeve-type pressurizing structure, the PLC controller collects the hydraulic pressure value in the oil passage in real time. This monitoring action is carried out throughout the entire downward movement of the sleeve-type pressurizing structure. During normal extrusion and feeding process, because the molten metal at the feeding target location is in a paste-like region where solid and liquid coexist, it has certain rheological plasticity and compressibility. The pressure build-up in the hydraulic chamber is a relatively gentle and gradual process, and its pressure rise rate is usually maintained within a stable range that matches the flow resistance of the molten metal.

[0044] Specifically, this invention also introduces anomaly detection logic based on the rate of change. When the hydraulic pressure rises at a rate exceeding a preset threshold within a unit of time after the start of oil supply, the PLC controller controls the solenoid directional valve to switch to the return oil position for unloading and outputs an alarm signal. The preset threshold is primarily based on the upper limit of historical pressure curve statistics under normal extrusion conditions and the rated safety margin of the hydraulic system. For example, in ADC12 aluminum alloy die-casting, the pressure rise rate during normal extrusion is typically between 5 MPa / s and 15 MPa / s, while the instantaneous rise rate during a jamming fault often exceeds 50 MPa / s or even higher. By setting the preset threshold within a reasonable range (e.g., 30 MPa / s), the system can accurately identify abnormal mechanical blockages within milliseconds and immediately cut off the power source pressure relief protection, thereby effectively preventing serious equipment accidents such as mold surface crushing, sleeve breakage, or hydraulic component rupture caused by forced extrusion. This monitoring method, which is based on dynamic rate of change rather than absolute pressure value, can detect potential faults earlier than traditional pressure limit protection, significantly improving the system's operational safety in harsh high-temperature environments.

[0045] Furthermore, in step S5, the pressure holding control stage after the sleeve-type pressurizing structure advances to the preset stroke, this application abandons the fixed-duration pressure holding mode commonly used in traditional technologies, and instead adopts an adaptive pressure holding strategy based on motion state feedback. Specifically, the PLC controller determines the pressure holding duration based on the advancing speed of the sleeve-type pressurizing structure and the preset stroke. In actual production, affected by factors such as alloy melt temperature fluctuations, changes in mold thermal equilibrium state, and differences in lubrication conditions, the apparent viscosity and flow resistance of the molten metal in the semi-solid state are not constant. This directly leads to batch-to-batch and even mold-to-mold dispersion in the actual advancing speed of the sleeve-type pressurizing structure under the same hydraulic driving force. If a fixed holding time is used, a faster actual advance speed indicates good molten metal flow and low filling resistance. In this case, maintaining the original holding time for an extended period could lead to localized overpressure, causing flash in the casting or elastic deformation of the mold. Conversely, a slower actual advance speed indicates high molten metal viscosity or narrow feeding channels. Insufficient holding time prevents the liquid metal from fully filling the dendrite gaps, resulting in underpressure feeding and difficulty in eliminating shrinkage defects. Therefore, this embodiment dynamically derives the optimal holding time under the current operating conditions by using real-time acquired advance speed and preset stroke as variables. For example, the holding time can be inversely proportional to the advance speed, or obtained through lookup interpolation using a pre-calibrated speed-time mapping table. This dynamic calculation mechanism ensures that regardless of fluctuations in operating conditions, the pressurization applied to the hot spot region remains within the optimal window—sufficient to compact shrinkage without overloading—achieving robust control of process quality. Subsequently, after the sleeve-type pressurizing structure advances to the preset stroke, the PLC controller controls the hydraulic source to maintain pressure for the determined holding time. After the dynamically calculated pressure holding time ends, the PLC controller controls the solenoid directional valve to switch to the oil return position, causing the sleeve-type pressurization structure to retract.

[0046] Specifically, after the PLC controller unloads the hydraulic power source, it controls the solenoid directional valve to switch to the return oil position. The hydraulic oil in the sealed hydraulic chamber flows back to the return oil circuit of the external hydraulic power source through the oil circuit channel. The sleeve-type pressurizing structure moves upward and retracts under the action of external reset force. During this retraction process, accurately determining whether the sleeve has truly returned to its initial position is crucial, because if the sleeve does not fully reset and the extrusion end face protrudes from the upper mold cavity surface, it will directly lead to mold crushing or casting scrap during the next mold closing. To this end, this application adopts a non-contact detection scheme based on hydraulic parameter feedback. That is, when the extrusion end face of the sleeve-type pressurizing structure is flush with the upper mold cavity surface, the PLC controller detects that the pressure in the hydraulic chamber has dropped to the return oil back pressure value through the pressure sensor set in the hydraulic chamber, and then determines that the sleeve-type pressurizing structure has fully retracted.

[0047] Specifically, the return oil back pressure value does not refer to the zero-pressure state after the hydraulic system is completely unloaded, nor is it the high-pressure value during operation. Rather, it is a steady-state pressure characteristic value with specific physical significance that lies between the two. Its formation mechanism is as follows: When the sleeve-type pressurizing structure moves upward under the drive of the return spring or return cylinder, the hydraulic oil in the sealed hydraulic chamber is discharged and flows back to the oil tank through the oil passage. At this time, due to the friction resistance along the oil passage, the throttling effect of the return port of the electromagnetic reversing valve, and the mechanical reaction force of the reset mechanism itself, a low-level dynamic equilibrium pressure is maintained in the hydraulic chamber. Once the extrusion end face of the sleeve-type pressurizing structure accurately reaches and aligns with the upper mold cavity surface, its axial movement is mechanically limited and forcibly terminated. The volume of the hydraulic chamber no longer changes, and the oil discharge flow stops. At this point, the value collected by the pressure sensor will stabilize within a specific range determined only by the static resistance of the return oil pipeline and the reset force. This range is the return oil back pressure value. Conversely, if the sleeve fails to return to its original position due to jamming or obstruction by foreign objects, the pressure in the hydraulic chamber will exhibit continuous fluctuations, abnormal increases, or an inability to stabilize within that specific range. Therefore, by comparing the real-time detected pressure with the preset return oil back pressure range, the PLC controller can accurately infer the mechanical positioning state of the sleeve without relying on any additional position sensing elements.

[0048] This back pressure-based judgment mechanism offers significant advantages over traditional technologies. In the die-casting production environment of motorcycle parts, molds operate at temperatures exceeding 200°C to 300°C for extended periods, accompanied by mold release agent spraying, molten metal splashing, and high-frequency vibration. If conventional linear displacement sensors (such as LVDTs) or proximity switches are used to detect sleeve positions, these precision electronic components are highly susceptible to failure due to thermal degradation, signal drift, or contamination. Furthermore, additional deep holes need to be drilled in the mold body to install the sensor, which not only weakens the mold's strength but also increases the difficulty of cooling water circuit layout and the risk of leakage. This embodiment cleverly reuses the pressure monitoring function already present in the hydraulic system, transforming "mechanical position detection" into "hydraulic state recognition," completely avoiding the introduction of fragile electronic sensing components into the high-temperature core area. Simultaneously, since pressure sensors are typically installed on the back of the upper mold body or on the oil distribution block, away from the cavity surface, their ambient temperature is relatively low, resulting in significantly higher operational stability than direct-contact position sensors.

[0049] By numerically simulating the solidification process using casting simulation software, the final solidification region in the solid-liquid coexistence range of the temperature field is accurately identified as the feeding target. Based on the spatial superposition comparison algorithm, the nearest sleeve-type pressure structure is automatically selected as the driving object. In principle, this eliminates the feeding blind zone caused by the position deviation of the traditional fixed extrusion pin, significantly improving the accuracy of the feeding position and thus improving the molding quality of motorcycle parts.

[0050] Example 2: Please refer to Figures 2-4 This embodiment provides a local extrusion and shrinkage compensation system for motorcycle parts molds. This system is used to execute the shrinkage compensation method, providing a material carrier for precise local extrusion and shrinkage compensation. The shrinkage compensation system includes an upper mold body 2, a lower mold body 1, multiple sleeve-type pressurizing structures 3, a PLC controller, and multiple solenoid directional valves.

[0051] Specifically, the upper mold body 2 has multiple mounting through holes extending from the back to the cavity surface in its middle. These mounting through holes are arranged in an array on the upper mold body 2 and each corresponds to a different area of ​​the mold cavity. This array layout is not random but is pre-designed based on the thermal distribution patterns of typical motorcycle parts (such as the lower cylinder block of an engine), ensuring that each mounting through hole covers a potential area prone to shrinkage cavities, such as the crankshaft support beam, oil filter mounting base, or high-pressure oil passage intersection. Each sleeve-type pressurizing structure 3 is slidably disposed within its respective mounting through hole, and a sealed hydraulic cavity is formed between the upper end of each sleeve-type pressurizing structure 3 and the upper wall of the corresponding mounting through hole. This sealed hydraulic cavity is the core unit for power conversion. Its upper boundary is formed by the sealing structure at the top of the mounting through hole or the upper mold body 2 itself, and its lower boundary is formed by the stepped surface of the sleeve-type pressurizing structure 3 or the piston head. The sidewalls are sealed by the fit between the precision-machined hole wall and the outer circle of the sleeve. When high-pressure hydraulic oil is injected into the cavity, the hydraulic pressure is directly converted into a downward axial thrust of the sleeve-type pressurizing structure 3. Multiple independent oil passages are opened inside the upper mold body 2. One end of each oil passage connects to a sealed hydraulic cavity, and the other end extends to the back of the upper mold body 2 with an independent oil passage interface. This independent oil passage design of "one cavity, one passage, one interface" ensures that each sleeve-type pressurizing structure 3 can be addressed and controlled independently without interference, thus realizing the flexible feeding capability of activating specific pressurizing units as needed based on simulation results. The lower end face of each sleeve-type pressurizing structure 3 forms an extrusion end face at the cavity surface of the upper mold body 2. This extrusion end face directly participates in the formation of the cavity surface in the mold-closed state, and during the extrusion action, it acts as a force-applying medium in contact with the molten metal.

[0052] An external hydraulic power source is connected to each oil circuit interface via oil pipes. Each oil circuit interface is equipped with an independent solenoid directional valve on the pipeline between it and the external hydraulic power source. The signal input terminal of the PLC controller is connected to the injection end signal output terminal of the die-casting machine, and each control output terminal of the PLC controller is connected to the signal input terminal of each solenoid directional valve. The inlet and outlet ports of each solenoid directional valve are connected to the outlet and return oil circuits of the external hydraulic power source, respectively. The working ports of each solenoid directional valve are connected to the corresponding oil circuit interface on the back of the upper mold body 2 via oil pipes. Through the above electrical-hydraulic connection, the PLC controller can precisely schedule any combination of sleeve-type pressurizing structures 3 to perform extrusion actions based on the die-casting machine's timing signals and the independent control logic of each channel.

[0053] Furthermore, the guide section length of each sleeve-type pressurizing structure 3 is greater than the guide hole section length of the corresponding mounting through hole. When the sleeve-type pressurizing structure 3 is in its retracted position, the guide section is located within the guide hole section of the mounting through hole and slides against the inner wall of the guide hole section. The lower end face of the sleeve-type pressurizing structure 3 is flush with the cavity surface of the upper mold body 2. This dimensional fit relationship has significant engineering implications. The guide section length being greater than the guide hole section length means that even when the sleeve-type pressurizing structure 3 descends to its maximum working stroke limit position, a considerable portion of its guide section remains within the guide hole section of the mounting through hole, maintaining effective guiding support at all times. This avoids the risk of lateral load and jamming caused by guide slippage, especially under harsh working conditions involving tens of megapascals of compressive force and thermal deformation, ensuring the smoothness and reliability of the movement. At the same time, when retracting to the original position, the extrusion end face is strictly flush with the cavity surface. This prevents the end face from protruding, which could cause the mold to crush or leave indentations on the casting surface during mold closing. It also avoids the end face from being concave, which could cause incomplete filling of the molten metal or the formation of flash. This precise control of geometric relationships is the foundation for ensuring mold life and the appearance quality of the casting.

[0054] To optimize the hydraulic circuit layout and improve maintenance convenience, an oil distribution block is fixed to the back of the upper mold body 2. All hydraulic circuit interfaces are centrally located on this block. The block contains internal oil channels corresponding to each interface, with one end connected to the corresponding interface and the other end extending to the side of the block with a pipe connector. Specifically, the oil distribution block acts as an integrated hub connecting the internal hydraulic circuits and external hydraulic lines. Without it, multiple oil pipes would need to be directly inserted deep into the back of the upper mold body 2, resulting in limited assembly space, difficult operation, and a limited bending radius that makes them prone to fatigue and damage. The oil distribution block transforms the dispersed internal interfaces into standardized pipe connectors centralized on the side, significantly simplifying external piping and making the back of the mold cleaner and more compact. More importantly, when replacing or repairing a hydraulic circuit component, only the corresponding connector on the oil distribution block needs to be removed, or the entire block can be removed without any machining or disassembly of the upper mold body 2, significantly reducing maintenance difficulty and downtime.

[0055] To address the reliability issues of moving parts under high-temperature and heavy-load conditions, sliding bearings are installed between the side walls of each sleeve-type pressure structure 3 and the inner walls of the guide holes of the corresponding mounting through holes. The sleeve-type pressure structure 3 slides against the inner walls of the guide holes through the sliding bearings. In die-casting production, the temperature of the upper mold body 2 is usually maintained above 200℃. Due to direct contact with molten metal and repeated frictional heat generation, the local temperature of the sleeve-type pressure structure 3 may be even higher. If a traditional direct steel-to-steel fit is used, the gap may easily disappear and seize due to the difference in thermal expansion coefficients, or lubrication failure may exacerbate wear. This embodiment introduces sliding bearings (such as copper-based self-lubricating bearings or wear-resistant alloy bearings inlaid with graphite). Utilizing their low coefficient of friction, good thermal conductivity, and self-lubricating properties, they effectively isolate the direct metal-to-metal contact between the sleeve and the mold body, absorb the dimensional changes caused by thermal deformation, significantly reduce the probability of jamming, and extend service life. In addition, as independent wear parts, the sliding bearings can be replaced separately after wear exceeds the limit, without scrapping the expensive upper mold body 2, further demonstrating the modular and maintainable design concept of the system.

[0056] Through the aforementioned hardware architecture, this embodiment constructs a highly modular, independently controllable, and adaptable local extrusion and feeding execution system suitable for harsh working conditions. The array-distributed sleeve-type pressurization structure 3, combined with independent oil circuits, provides a flexible physical execution end for digitally selected feeding. Precise guiding and sliding bearing design ensures operational reliability under high-frequency, high-temperature operations. The integrated oil distribution blocks and leveling reset mechanism balance ease of maintenance with casting quality. This system serves as the material basis for the aforementioned method embodiment, enabling the stable implementation of a precise feeding strategy based on solidification simulation in industrial settings.

[0057] Specifically, in this embodiment, taking the die-casting production of the lower cylinder block of a certain model of motorcycle engine as an example, the local extrusion and shrinkage compensation method and system for molds described in the aforementioned embodiments are comprehensively applied to further illustrate the specific implementation and technical effects of the technical solution of this application in actual industrial scenarios. The lower cylinder block of the engine is die-cast from ADC12 aluminum alloy material, and its overall structure is box-shaped with a main wall thickness of about 3.5mm. However, the width of the support beam area used to install the crankshaft in the middle reaches 20mm to 22mm, which is a typical local thick and hot spot. Moreover, high-pressure oil passages are arranged inside this area, requiring extremely high airtightness.

[0058] Specifically, in the process preparation stage, the solidification process of the lower cylinder block was first numerically simulated using ProCAST casting simulation software. The simulation results showed that the area slightly below the center of the crankshaft support beam was the final solidification region, where the temperature field remained within the solid-liquid coexistence range for a relatively long time. Furthermore, a shrinkage cavity risk zone with a volume of approximately 120 mm³ was predicted to exist in this region, about 8 mm below the cavity surface. Based on the point selection logic described in Example 2, the system established a feeding coverage area centered on the axes of the arrayed sleeve-type pressurizing structures 3. Through spatial superposition and comparison, the No. 3 sleeve-type pressurizing structure located directly above the crankshaft support beam was determined as the driving object, as its axis has the shortest horizontal distance to the predicted shrinkage cavity center (only 2 mm), enabling effective feeding with minimal flow resistance.

[0059] Regarding the extrusion parameter settings, based on the simulated temperature field evolution curve, the temperature at the target location for compensation drops to the solid-liquid coexistence temperature range of the ADC12 alloy (approximately 570°C to 590°C) after 4.5 seconds from the end of the filling process. Therefore, the extrusion delay time is set to 4.5 seconds. Simultaneously, based on the stroke calculation model in Example 2, the volume V_hot of the hot spot is known to be 120 mm³, the solidification volume shrinkage rate ε of the ADC12 aluminum alloy is taken as 6.5%, the extrusion end face area A of the No. 3 sleeve-type pressure structure 3 is 78.5 mm² (corresponding to a diameter of 10 mm), and the safety factor K is taken as 1.3 based on the alloy's fluidity and mold complexity. Substituting these values ​​into the formula, the preset stroke L is calculated to be approximately 12.9 mm. In actual production, to facilitate execution by the PLC controller, this preset stroke is rounded down to 13.0 mm.

[0060] During production, after the die-casting machine completes filling and outputs an injection end signal to the PLC controller, the system automatically waits for 4.5 seconds. Subsequently, the PLC controller opens the corresponding solenoid directional valve, allowing high-pressure hydraulic oil to enter the sealed hydraulic chamber above the No. 3 sleeve-type pressurizing structure 3 via the oil distribution block and independent oil circuit channel. This pushes the structure downwards and applies increased pressure to the semi-solidified crankshaft crossbeam molten metal. During this process, the PLC controller monitors the oil circuit pressure rise rate in real time, ensuring it remains within the normal range (approximately 8 MPa / s) and does not trigger the anti-jamming alarm. When the sleeve-type pressurizing structure 3 advances to a preset stroke of 13.0 mm, the system dynamically calculates the holding pressure duration based on the current forward speed (15 mm / s), which is approximately 0.87 seconds, and maintains a constant pressure during this period. After the pressure holding is completed, the reversing valve switches to the return oil position, and the sleeve-type pressurizing structure 3 retracts under the action of the return spring. After the PLC controller detects that the hydraulic chamber pressure has stabilized and dropped to the return oil back pressure value of 0.3MPa, it determines that it has been completely reset and is flush with the cavity surface of the upper mold body 2. The entire feeding cycle time is precise and controllable.

[0061] By adopting the technical solution of this application, the internal quality of the lower cylinder block of this motorcycle engine has been significantly improved. X-ray flaw detection revealed that shrinkage cavities and porosity defects in the crankshaft support beam area have been largely eliminated, with the defect level improved from level 3 to below level 1. More importantly, in subsequent high-pressure oil passage airtightness tests, the product leakage rate decreased from over 12% under traditional processes to below 0.5%, significantly improving the first-pass yield. This achievement is essentially due to the precise point selection based on solidification simulation and the time-delay control based on the temperature field, ensuring that the extrusion action occurs strictly within the semi-solid window period when the molten metal's plasticity is optimal. Furthermore, through direct contact pressure application and an adaptive pressure holding strategy, the boost pressure can be transferred seamlessly and fully to the hot spot core, forcing the solute-rich liquid metal to completely fill the dendrite interstices, thus fundamentally solving the problem of localized shrinkage porosity in complex thin-walled box-type castings.

[0062] Furthermore, the embodiments of the present invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for partial extrusion and shrinkage compensation using a mold for motorcycle parts, characterized in that, Includes the following steps: The solidification process of motorcycle parts was numerically simulated using casting simulation software. Based on the simulation results, the area where the temperature field was in the solid-liquid coexistence range and the area that was finally solidified was determined as the feeding target location. Based on the corresponding area of ​​the feeding target location on the mold cavity, the corresponding driven sleeve-type pressure structure in the upper mold body was determined. After the mold is closed, the molten metal is injected into the mold cavity under high pressure to complete the filling. After the die casting machine finishes the injection action, it outputs an injection end signal to the PLC controller. After receiving the injection end signal, the PLC controller starts timing and waits for the preset extrusion delay time. This extrusion delay time is determined based on the time required for the temperature field at the target location to drop to the solid-liquid coexistence temperature range in the simulation results. After the extrusion delay time is reached, the PLC controller controls the external hydraulic source to supply oil to the oil passage inside the mold. The hydraulic oil enters the sealed hydraulic cavity between the sleeve-type pressurizing structure and the upper mold body, pushing the sleeve-type pressurizing structure to move towards the lower mold body. The extrusion end face of the sleeve-type pressurizing structure directly applies pressurizing pressure to the molten metal at the feeding target position. After the sleeve-type pressurizing structure advances to the preset stroke, the PLC controller controls the hydraulic source to maintain pressure, and then the PLC controller controls the hydraulic source to unload, and the sleeve-type pressurizing structure returns to its original position.

2. The method for partial extrusion and shrinkage compensation of motorcycle parts according to claim 1, characterized in that, The solidification process of motorcycle parts is numerically simulated using casting simulation software. Based on the simulation results, the region where the temperature field is in the solid-liquid coexistence range and is the last to solidify is determined as the feeding target location. Furthermore, based on the corresponding region on the mold cavity of the feeding target location, the corresponding driven sleeve-type pressurization structure in the upper mold body is determined, including: The predicted volume and location coordinates of shrinkage cavities and porosity in each region during the solidification process were obtained using casting simulation software. The compensation coverage area of ​​each sleeve-type pressurizing structure is established with the axial position of each sleeve-type pressurizing structure as the center and the effective compensation radius of the sleeve-type pressurizing structure as the radius; Spatially superimpose and compare the shrinkage and loosening prediction locations of each shrinkage coverage area with the shrinkage and loosening prediction locations of each area, and select one or more sleeve-type pressurization structures with the shortest distance between the center of the shrinkage coverage area and the shrinkage and loosening prediction location as the driving object. The PLC controller controls an external hydraulic source to synchronously supply oil to the oil passages of the selected sleeve-type pressurization structure.

3. The method for partial extrusion and shrinkage compensation of motorcycle parts as described in claim 2, characterized in that, The step of spatially superimposing and comparing each shrinkage coverage area with the predicted shrinkage and loosening position of each area, and selecting one or more sleeve-type pressurization structures with the shortest distance between the center of the shrinkage coverage area and the predicted shrinkage and loosening position as the driving object includes: A two-dimensional domain of action for each sleeve-type pressurization structure is established with the center of the compensation coverage area as the origin and the outer boundary of the compensation coverage area as the effective boundary. Project the spatial coordinates of the predicted shrinkage and porosity positions onto the two-dimensional action plane, and determine one by one whether the projection point of each predicted shrinkage and porosity position falls within the two-dimensional action area of ​​each sleeve-type pressurization structure. When the projection point of the same shrinkage and loosening prediction position falls into the two-dimensional action domain of multiple sleeve-type pressurizing structures at the same time, the distance between the projection point and the center of the compensation coverage area of ​​each sleeve-type pressurizing structure is calculated, and the sleeve-type pressurizing structure with the smallest distance is selected as the corresponding driving object of the shrinkage and loosening prediction position.

4. The method for partial extrusion and shrinkage compensation of motorcycle parts as described in claim 2, characterized in that, The compensation coverage area of ​​each sleeve-type pressurizing structure, centered on its axial position and with its effective compensation radius as the radius, includes: The pressure transmission attenuation curves of each sleeve-type pressurizing structure under different extrusion strokes were obtained by casting simulation software. Taking the center of the extrusion end face as the starting point and the critical position where the pressure transmission attenuates to the point where it is insufficient to drive the flow of molten metal as the boundary, the initial value of the effective feeding radius of each sleeve-type pressurizing structure was determined. For each determined initial effective shrinkage radius, the radius is gradually reduced and enlarged proportionally to form multiple radius candidate values. For each radius candidate value, the shrinkage coverage area corresponding to the shrinkage hole and loosening prediction position is re-executed. The number of shrinkage hole and loosening prediction positions falling into the corresponding shrinkage coverage area under each radius candidate value is counted. The minimum value among the radius candidate values ​​whose coverage number meets the preset threshold is taken as the final effective shrinkage radius.

5. The method for partial extrusion and shrinkage compensation of motorcycle parts according to claim 1, characterized in that, The method for determining the preset travel route includes the following steps: The volume of the hot spot that needs to be compressed is obtained from the 3D model of the motorcycle parts; Multiply the volume of the hot spot by the solidification volume shrinkage rate of the alloy used in the component to obtain the theoretical shrinkage compensation volume; Divide the theoretical compensation volume by the extrusion end face area of ​​the sleeve-type pressure structure and multiply by the safety factor to obtain the preset stroke value.

6. The method for partial extrusion and shrinkage compensation of motorcycle parts according to claim 5, characterized in that, The process of obtaining the volume of the hot spot that needs to be compensated based on the 3D model of the motorcycle parts includes: Temperature field data and solid fraction data of each grid cell at the hot spot of motorcycle parts were obtained by casting simulation software during the solidification process. Using a solid fraction of 90% as the solidification cutoff condition, multiple temperature gradient layers with solid fractions gradually increasing from the extrusion end face of the sleeve-type pressurized structure towards the center of the hot spot were extracted from the temperature field of the hot spot. Calculate the solidification shrinkage volume corresponding to each temperature gradient layer. For these multiple temperature gradient layers, accumulate the solidification shrinkage volume sequentially from the extrusion end face to the center of the hot spot. After each layer is accumulated, calculate the difference between the current accumulated value and the theoretical compensation volume. When the difference is in a stable state, configure the corresponding accumulated value as the volume of the hot spot that needs compensation.

7. A local extrusion and shrinkage compensation system for a motorcycle part mold, characterized in that, The feeding system is used to perform the feeding method as described in any one of claims 1 to 6, and includes an upper mold body, a lower mold body, multiple sleeve-type pressurizing structures, a PLC controller, and multiple solenoid directional valves; The upper mold body has multiple mounting through holes in the middle that extend from the back to the cavity surface. These mounting through holes are arranged in an array on the upper mold body and each corresponds to a different area of ​​the mold cavity. Each sleeve-type pressure structure is slidably installed in each mounting through hole. The upper end of each sleeve-type pressure structure and the upper end wall of the corresponding mounting through hole form a closed hydraulic cavity. Multiple independent oil passages are opened inside the upper mold body. One end of each oil passage is connected to each closed hydraulic cavity, and the other end extends to the back of the upper mold body and is provided with an independent oil passage interface. The lower end face of each sleeve-type pressure structure forms an extrusion end face at the cavity surface of the upper mold body. An external hydraulic power source is connected to each oil circuit interface through oil pipes. Each oil circuit interface is equipped with an independent solenoid directional valve on the pipeline between it and the external hydraulic power source. The signal input terminal of the PLC controller is connected to the injection end signal output terminal of the die casting machine. Each control output terminal of the PLC controller is connected to the signal input terminal of each solenoid directional valve. The inlet and outlet ports of each electromagnetic directional valve are connected to the outlet and return lines of an external hydraulic power source, respectively. The working ports of each electromagnetic directional valve are connected to the corresponding oil circuit interfaces on the back of the upper mold body via oil pipes.

8. The local extrusion and shrinkage compensation system for motorcycle parts according to claim 7, characterized in that, The length of the guide section of each sleeve-type pressurizing structure is greater than the length of the guide hole section of the corresponding mounting through hole. When the sleeve-type pressurizing structure is in the retracted position, the guide section is located inside the guide hole section of the mounting through hole and slides with the inner wall of the guide hole section. The lower end face of the sleeve-type pressurizing structure is flush with the cavity surface of the upper mold body.

9. The local extrusion and shrinkage compensation system for motorcycle parts according to claim 7, characterized in that, An oil distribution block is fixed on the back of the upper mold body. All oil circuit interfaces are centrally located on the oil distribution block. The oil distribution block has internal oil channels that correspond one-to-one with each oil circuit interface. One end of each internal oil channel is connected to the corresponding oil circuit interface, and the other end extends to the side of the oil distribution block and is equipped with a pipe joint.

10. The local extrusion and shrinkage compensation system for motorcycle parts according to claim 7, characterized in that, Each sleeve-type pressurizing structure has a sliding bearing installed between its side wall and the inner wall of the guide hole of the corresponding mounting through hole. The sleeve-type pressurizing structure slides in contact with the inner wall of the guide hole through the sliding bearing.

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