A die-casting die with inserts and a die-casting production process

Abstract

The application relates to the technical field of metal casting, and provides a die-casting die with inserts and a die-casting production process. The die-casting die with inserts comprises a die body, a fixed inserting rod and a positioning block. The die body comprises a first die core and a second die core. After the first die core and the second die core are combined, a die cavity is formed in the die body. The fixed inserting rod is connected to the first die core. One end of the fixed inserting rod extends towards the die cavity and is sleeved with an insert. One end of the insert is used for abutting against the inner wall of the die cavity, and the other end of the insert is provided with a limiting groove. The positioning block is detachably connected to the end of the fixed inserting rod away from the first die core, and the positioning block is clamped into the limiting groove and used for abutting against the insert. The material of the positioning block has a melting point lower than the pouring temperature of the pouring metal liquid, so that the positioning block can melt and disappear under the action of the residual heat of the castings after pouring. The application can improve the axial movement and deviation of the inserts in the existing die-casting process due to the impact force during the metal liquid filling process.

Description

Technical Field

[0001] This application relates to the technical field of metal casting, and in particular to a die casting mold with inserts and a die casting production process. Background Technology

[0002] In the die-casting process of metal products, thicker sections often exhibit slow solidification rates, leading to internal defects such as shrinkage cavities and cracks, severely impacting the product's structural strength and processing quality. Existing technologies typically employ core-pulling processes or external feeding structures to address this issue; however, these methods have structural limitations, making it impossible to achieve core-pulling or effective feeding in certain specific areas, thus hindering defect elimination. Therefore, a common solution is to pre-place a dense metal insert within the mold cavity. This insert fuses with the molten metal during die casting, becoming part of the final casting and replacing the as-cast structure that is prone to shrinkage cavities, thereby ensuring the density and strength of the machined area.

[0003] However, a critical technical problem has emerged in practical applications: during the molten metal pouring process, the molten metal flowing into the mold cavity exerts an impact and scouring effect on the inserts, potentially causing axial movement and deviation from the preset position. This affects the welding quality and the final casting accuracy, leading to defects such as hole misalignment and abnormal strength during processing, and even product scrap. Furthermore, since the materials of the inserts and the positioning structures within the mold used to install them are usually different, they have different coefficients of thermal expansion. Thermal stress can easily be generated during molten metal injection and cooling, which may also cause displacement of the inserts within the positioning structures of the mold cavity, resulting in decreased processing accuracy.

[0004] Therefore, ensuring the stability of inserts during the casting process under high pressure and rapid filling conditions has become a key technical problem that urgently needs to be solved. Summary of the Invention

[0005] In order to improve the problem that inserts in the existing die casting process may move axially or be misaligned due to impact force during the filling of molten metal, resulting in a decrease in the final casting accuracy or even scrap, this application provides a die casting mold with inserts and a die casting production process.

[0006] This application provides a die-casting mold with inserts, employing the following technical solution: A die-casting mold with inserts, comprising: The mold body includes a first mold core and a second mold core. After the first mold core and the second mold core are closed, a mold cavity is formed inside the mold body. A fixed insert rod is connected to the first mold core. One end of the fixed insert rod extends toward the mold cavity and is fitted with an insert. One end of the insert is used to abut against the inner wall of the mold cavity, and the other end is provided with a limiting groove. A positioning block is detachably connected to the end of the fixing rod away from the first mold core, and the positioning block is engaged in the limiting groove to abut against the insert; The material of the positioning block has a melting point lower than the pouring temperature of the molten metal, which allows the positioning block to melt and disappear under the residual heat of the casting after pouring; and the positioning block has a hollow structure, which makes the time from contact with the molten metal to complete melting longer than the time it takes for the molten metal to form a solidification constraint shell on the outer periphery of the insert.

[0007] By adopting the above technical solution, the insert is axially limited at both ends by abutting against the inner wall of the mold cavity at one end and being engaged in the limiting groove by a positioning block at the other end. This effectively resists axial movement caused by fluid impact and thermal expansion during the molten metal filling stage. The melting point of the positioning block is lower than the pouring temperature of the molten metal, allowing it to be gradually melted away by the residual heat of the casting during the heat preservation stage after pouring, ultimately leaving no extra structure inside the casting. This facilitates the axial removal of the fixing rod laterally without the need for complex lateral core pulling or disassembly mechanisms. At the same time, by pre-setting the heat capacity of the positioning block, the complete melting time of the positioning block is longer than the formation time of the solidification constraint shell around the insert. This ensures that the positioning block maintains its structural integrity to maintain its limiting function during the filling stage and the early solidification stage. Only after the solidification shell has tightened the insert and taken over the limiting function does the positioning block completely melt, achieving an orderly switch between support and melting.

[0008] Optionally, the outer surface of the positioning block is provided with a delayed melting layer, the melting point of which is higher than the melting point of the positioning block but not higher than the pouring temperature of the molten metal.

[0009] By adopting the above technical solution, the delayed melting layer is coated on the outer surface of the positioning block substrate. When the molten metal initially contacts the positioning block, the delayed melting layer, due to its higher melting point, preferentially protects the positioning block from being immediately eroded, thereby increasing the structural retention time of the positioning block and further ensuring the positioning block's limiting ability during the molten metal filling stage. After the delayed melting layer melts, the substrate continues to melt under the continuous residual heat and eventually disappears completely.

[0010] Optionally, the fixing rod includes a coaxial and interconnected insertion rod segment and a connecting rod segment. The insertion rod segment is used to insert into the insert, a portion of the connecting rod segment extends into the limiting groove, and the positioning block is sleeved on one end of the connecting rod segment and detachably connected to the connecting rod segment.

[0011] By adopting the above technical solution, the fixed insertion rod is divided into two parts: the insertion rod section and the connecting rod section. The insertion rod section is responsible for the radial positioning and support of the insert, while the connecting rod section is responsible for bearing the positioning block. The two sections are coaxially connected. After the positioning block is completely melted, there is no radial interference between the connecting rod section and the inner cavity of the insert, and it can be smoothly pulled out along the axial direction.

[0012] Optionally, the positioning block includes two mesh sheets spaced apart along the axial direction of the fixed insert rod, a connecting cylinder and several support rods connected between the two mesh sheets; the connecting cylinder is sleeved outside the connecting rod segment and is detachably connected to the connecting rod segment.

[0013] By adopting the above technical solution, two mesh sheets are spaced apart along the axial direction and respectively abut against the two side walls of the limiting groove, enhancing the axial resistance to movement. The connecting sleeve is sleeved outside the connecting rod section, providing a base for the installation connection between the mesh sheets and the fixed insert rod. The hollow structure of the mesh sheets significantly reduces the material usage and heat capacity of the positioning blocks, allowing them to be melted by residual heat more quickly during the heat preservation stage. On the other hand, it allows the molten metal to pass through the mesh of the mesh sheets and fill the limiting groove, which is beneficial for the molten metal to fully contact the positioning blocks.

[0014] Optionally, the positioning block includes a connecting ring and a limiting abutment ring coaxially sleeved and fixed outside the connecting ring. The connecting ring is a solid structure, and the connecting ring is detachably connected to the connecting rod segment. The outer diameter of the connecting ring is smaller than the outer diameter of the plug-in rod segment. The limiting abutment ring is a hollow structure.

[0015] By adopting the above technical solution, the connecting ring serves as the structural basis for the load-bearing limiting abutment ring. The solid structure of the connecting ring ensures the reliability of the connection with the connecting rod segment, and the outer diameter of the connecting ring is not greater than the outer diameter of the insertion rod segment. This ensures that even if the connecting ring is not completely melted due to its solid structure, it will not cause radial interference with the inner wall of the insert after the positioning abutment block melts and the fixing rod is pulled out. The limiting abutment ring has a hollow structure, which is conducive to the complete melting of the limiting abutment ring.

[0016] Optionally, an annular constriction neck is connected between the limiting abutment ring and the connecting ring.

[0017] By adopting the above technical solution, an annular neck is provided at the connection between the limiting ring and the connecting ring. The annular neck has the smallest cross-section, and during the heat preservation process, the annular neck is preferentially melted, so that the limiting ring and the connecting ring are separated. This is conducive to the rapid and complete melting of the limiting ring. Even if the connecting ring is not completely melted, it can be pulled out together with the fixed insert rod without affecting demolding.

[0018] Optionally, the mold cavity includes a molding injection cavity and a liquid inlet cavity. The liquid inlet cavity includes a plurality of gating channels spaced apart. One end of each gating channel is connected to the outside, and the other end is connected to the molding injection cavity. The liquid inlet cavity is arranged in a plurality of spaces around the molding injection cavity.

[0019] By adopting the above technical solution, multiple liquid inlet cavities are distributed around the molding cavity at intervals, so that the molten metal can enter the mold cavity from multiple directions at the same time to fill it. On the one hand, this makes the impact force on the insert from all directions more balanced, reducing the risk of the insert being displaced due to unilateral load during the filling process. On the other hand, it improves the uniformity of the molten metal filling, which is conducive to the synchronous solidification of the molten metal around the insert and promotes the uniform formation of the solidification constraint shell.

[0020] Optionally, a connecting groove is provided on the outer wall of the insert, and the connecting groove is annular.

[0021] By adopting the above technical solution, the annular connecting groove on the outer wall of the insert is filled with molten metal after the molten metal is filled. After solidification, an annular rib is formed in the groove that is mechanically interlocked with the insert, thereby enhancing the axial and circumferential bonding force between the insert and the casting.

[0022] Optionally, the material of the positioning block is compatible with molten metal metallurgy.

[0023] By adopting the above technical solution, the material of the positioning block is incorporated into the casting matrix after melting. Since the positioning block material is metallurgically compatible with the molten metal, it will not form harmful phases or brittle compounds in the casting, and will not affect the mechanical properties and microstructure quality of the casting in the molten area of ​​the positioning block.

[0024] This application also provides a die-casting production process, which adopts the following technical solution: The method of using a die-casting mold with inserts as described above includes the following steps: S1: Before die casting begins, prepare a solid insert and fit the insert onto the insertion rod section of the fixed insert, so that one end of the insert abuts against the inner wall of the mold body; then install the positioning block onto the connecting rod section of the fixed insert, and the positioning block is inserted into the limiting groove of the insert to axially limit the insert; S2: Close the mold body and pour molten metal into the mold cavity. The molten metal gradually wraps around the insert and the positioning block. The surface of the insert is fused with the molten metal and the molten metal forms a solidified constraint shell around the insert. S3: After pouring, keep the mold body in the closed state and keep it warm for a preset time, using the residual heat of the casting to completely melt the positioning block; S4: After the heat preservation is completed, start the cooling process to solidify the casting; S5: After cooling is complete, open the mold, pull out the fixing rod along the axial direction, and then take out the casting.

[0025] By adopting the above technical solution, the axial positioning of the insert is implemented by the positioning block before casting to ensure the stability of the insert position during the filling stage and the early stage of solidification. After casting is completed, the positioning block is naturally melted and disappeared during the heat preservation stage by the residual heat of the casting itself. No additional device or mechanism is required, the process is simple, and the fixing rod can be directly pulled out along the axial direction after the positioning block melts, making demolding operation simple.

[0026] In summary, this application includes at least one of the following beneficial effects: 1. This application achieves axial positioning of the insert during the molten metal filling stage by setting a low-melting-point positioning block at the end of the fixed insert rod and cooperating with the insert limiting groove, effectively preventing axial movement and displacement of the insert during high-pressure filling, and improving the forming accuracy and welding quality of the casting. 2. The positioning block in this application is designed with a hollow structure, which can melt and disappear naturally under the residual heat of the casting, without the need for secondary heating or additional disassembly mechanism. The process is simple and the cost is low. The fixing rod can be directly pulled out along the axial direction, making demolding operation convenient. 3. This application ensures reliable positioning during the filling stage and thorough melting during the heat preservation stage by pre-setting the heat capacity of the positioning block and setting a delayed melting layer, thus ensuring the positioning accuracy of the insert without affecting the integrity of the final structure of the casting. Attached Figure Description

[0027] Figure 1 This is a partial cross-sectional view of a die-casting mold with inserts according to Embodiment 1 of this application; Figure 2 This is an exploded structural diagram of the first mold core and the second mold core in Embodiment 1 of this application; Figure 3 This is a partial cross-sectional view of the first mold core and the second mold core when they are joined together in Embodiment 1 of this application; Figure 4 This is a cross-sectional view of the positioning component in Embodiment 1 of this application; Figure 5 This is an exploded structural diagram of the positioning component and insert in Embodiment 2 of this application; Figure 6 This is a cross-sectional view of the positioning component in Embodiment 2 of this application; Explanation of reference numerals in the attached drawings: 1. Mold body; 11. First mold core; 12. Second mold core; 13. Mold cavity; 131. Molding injection cavity; 132. Gating channel; 14. Gating pipe; 2. Positioning component; 21. Fixed insert rod; 211. Insert rod segment; 212. Connecting rod segment; 22. Positioning stop block; 221. Mesh sheet; 222. Connecting cylinder; 223. Support rod; 224. Connecting ring; 225. Limiting stop ring; 226. Annular neck; 3. Insert; 31. Limiting groove; 32. Connecting groove. Detailed Implementation

[0028] The following is in conjunction with the appendix Figure 1 -Appendix Figure 6 This application will be described in further detail.

[0029] Example 1

[0030] Embodiment 1 of this application provides a die-casting mold with inserts.

[0031] Reference Figure 1 and Figure 2 A die-casting mold with inserts includes a mold body 1 and a positioning assembly 2. The mold body 1 includes a moving mold and a fixed mold arranged opposite to each other. A first mold core 11 is embedded and fixed on the end face of the moving mold near the fixed mold, and a first groove is formed on the end face of the first mold core 11. A second mold core 12 is embedded and fixed on the end face of the fixed mold near the moving mold, and a second groove is formed on the end face of the second mold core 12. After the moving mold and the fixed mold are closed, the first groove and the second groove merge to form a mold cavity 13.

[0032] The mold cavity 13 includes a molding injection cavity 131 and a liquid inlet cavity. The molding injection cavity 131 serves as the molding space for the final casting, and the liquid inlet cavity guides external molten metal into the molding injection cavity 131. The liquid inlet cavity includes multiple spaced-apart pouring channels 132. Multiple pouring pipes 14 are fixed externally to the mold body 1, with each pouring channel 132 corresponding to one pouring pipe 14. One end of each pouring channel 132 connects to one end of a pouring pipe 14, and the other end connects to the molding injection cavity 131. In this embodiment, the pouring pipes 14 are fixed to the second mold core 12. The multiple liquid inlet cavities are circumferentially spaced around the molding injection cavity 131, allowing molten metal to enter the molding injection cavity 131 simultaneously from multiple directions. In this embodiment, there are two liquid inlet cavities, spaced circumferentially along the molding injection cavity 131. In other embodiments, the number of liquid inlet cavities can be three or four or more, adjustable according to the casting structure and the position of the insert 3.

[0033] Reference Figure 3 and Figure 4The positioning component 2 includes a fixing rod 21 and a positioning block 22. The fixing rod 21 passes through the first mold core 11, with one end threadedly fixed inside the first mold core 11 and the other end extending toward the mold cavity 13. In other embodiments, the specific types of the first mold core 11 and the second mold core 12 can be interchanged, and the fixing rod 21 can also be set on the fixed mold, as long as one end of the fixing rod 21 extends toward the mold cavity 13.

[0034] The fixed insert 21 includes a coaxial and integrally connected insert segment 211 and a connecting segment 212. The insert 3 is cylindrical, and the insert segment 211 is the main body of the fixed insert 21, used to insert into the inner cavity of the insert 3 for radial positioning and support. The outer diameter of the insert segment 211 matches the inner diameter of the inner cavity of the insert 3, that is, the outer diameter of the insert segment 211 is slightly smaller than the inner diameter of the inner cavity of the insert 3, so that the insert 3 can be smoothly fitted onto the insert segment 211. The cross-sectional shape of the insert segment 211 is usually circular, matching the cross-section of the inner cavity of the insert 3. In other embodiments, when the inner cavity of the insert 3 has a non-circular cross-section (such as a square, polygonal, or irregular cross-section), the cross-sectional shape of the insert segment 211 is also set accordingly to match the shape, so as to achieve circumferential positioning of the insert 3. The connecting segment 212 is located at the end of the insert segment 211 away from the first mold core 11 and is coaxial with the insert segment 211. The outer diameter of the connecting rod segment 212 is smaller than the outer diameter of the plug-in rod segment 211. The outer surface of the end of the connecting rod segment 212 away from the plug-in rod segment 211 may be provided with a connecting structure such as an external thread segment or a groove to achieve a detachable connection with the positioning block 22.

[0035] In this embodiment, the plug-in rod segment 211 and the connecting rod segment 212 are integrally formed structures. In other embodiments, the two can also be connected separately by threaded connection or interference fit, which facilitates the replacement of connecting rod segments 212 of different specifications to adapt to different positioning blocks 22 or inserts 3.

[0036] Reference Figure 3 and Figure 4 The insert 3 is prefabricated from metal material and can be an alloy tube made by forging or extrusion. Its internal structure is dense and free of shrinkage cavities. The insert 3 is fitted onto the insertion rod section 211 of the fixed insert rod 21. The end of the insert 3 closest to the first mold core 11 abuts against the inner wall of the mold cavity 13. A circular limiting groove 31 is formed at the end of the insert 3 furthest from the first mold core 11. The size of the limiting groove 31 matches that of the positioning block 22. After the positioning block 22 is engaged in the limiting groove 31, the outer wall of the positioning block 22 abuts against the inner wall of the limiting groove 31, working together with the inner wall of the mold cavity 13 to axially limit the insert 3. A portion of the connecting rod section 212 extends into the limiting groove 31 at the end of the insert 3 after the insert 3 is installed in place.

[0037] A connecting groove 32 is formed on the outer wall of the insert 3, and the connecting groove 32 is arranged in a ring around the circumference of the insert 3. One or more connecting grooves 32 can be provided, spaced apart along the axial direction of the insert 3. In this embodiment, only one connecting groove 32 is provided. When molten metal fills the mold cavity 13, the molten metal enters the connecting groove 32, and after solidification, forms an annular rib that mechanically interlocks with the insert 3 within the groove, enhancing the axial and circumferential bonding strength between the insert 3 and the casting. The cross-sectional shape of the connecting groove 32 can be a rectangular groove, a dovetail groove, or an arc-shaped groove, etc.

[0038] Reference Figure 3 and Figure 4 In this embodiment, the positioning block 22 includes two mesh sheets 221 spaced apart axially along the fixed insertion rod 21, a connecting cylinder 222 connected between the two mesh sheets 221, and several support rods 223. The two mesh sheets 221 are fixedly connected to both ends of the connecting cylinder 222, forming an annular shape. The axial distance between the two mesh sheets 221 matches the axial width of the limiting groove 31, allowing the two mesh sheets 221 to abut against the inner sidewall of the limiting groove 31. The connecting cylinder 222 is a thin-walled hollow cylinder, fitted over the connecting rod segment 212, and detachably connected to the connecting rod segment 212 via a threaded connection. In other embodiments, the connecting cylinder 222 and the connecting rod segment 212 can also be detachably connected via snap-fit ​​or interference fit. In this embodiment, the connecting cylinder 222 is made of a metal material with a melting point lower than the pouring temperature of molten metal, and can melt and disappear along with the mesh sheets 221 and support rods 223 during the heat preservation stage. Several support rods 223 are connected between two mesh sheets 221 and are arranged at intervals around the circumference of the connecting cylinder 222. The number of support rods 223 can be adjusted according to the required limiting force.

[0039] Furthermore, the material of the positioning block 22 is metallurgically compatible with the molten metal. After the positioning block 22 material melts, it can form a solid solution or eutectic structure with the molten metal matrix, without generating harmful brittle intermetallic compounds or segregated phases in the casting, thus not affecting the quality of the casting structure. The outer surface of the positioning block 22 is also provided with a delayed melting layer, the melting point of which is higher than the melting point of the positioning block 22 matrix material but not higher than the pouring temperature of the molten metal. When the molten metal initially contacts the positioning block 22, the delayed melting layer, due to its significantly higher melting point, preferentially remains solid, providing structural protection for the positioning block 22, delaying the exposure and erosion of the positioning block 22 matrix, and providing additional time margin for the positioning block 22 to maintain structural integrity during the filling stage. The delayed melting layer can be applied to the surface of the positioning block 22 matrix by spraying, hot-dip galvanizing, or electroless plating.

[0040] Specifically, the limiting groove 31 is located at one end of the insert 3 near the thick-walled region of the casting. During the die casting process, the thick-walled region of the casting has a large volume of molten metal, sufficient heat storage, and a low solidification and cooling rate; the overall melting point of the positioning block 22 is lower than the pouring temperature of the molten metal. Arranging the positioning block 22 near one end of the thick-walled region of the casting is beneficial for the positioning block 22 to continuously obtain sufficient residual heat during the heat preservation stage, which helps the positioning block 22 to melt.

[0041] In this design, the filling time of the molten metal into the mold cavity is set as t1, the time from contact with the molten metal to complete melting of the positioning block 22 is set as t2, and the time for the molten metal to form a solidified constraint shell around the insert 3 is set as t3. The positioning block 22 has a hollow structure, such that t2 > t3. The complete melting time t2 of the positioning block 22 must satisfy t2 > t3 > t1, meaning that the positioning block 22 can only completely lose its limiting ability after the insert 3 has been clamped by the solidified shell. The heat capacity of the positioning block 22 can be preset by material selection, adjustment of the total mass of the positioning block 22, and selection of the thickness and material of the delayed melting layer.

[0042] In other embodiments, to improve the heat preservation effect, an insulation layer or other insulation structure may be added to the outside of the mold body 1.

[0043] The installation position and quantity of the positioning components 2 are determined according to the actual needs of subsequent processing of the casting. In this embodiment, two sets of positioning components 2 are provided, and two inserts 3 are also provided accordingly.

[0044] In other embodiments, the positioning component 2 may contain only a fixed insert rod 21, with one end of the fixed insert rod 21 tapering to a frustum shape; the insert 3 is directly sleeved and snapped onto the fixed insert rod 21, and the insert 3 and the fixed insert rod 21 are connected by friction.

[0045] The implementation principle of a die-casting mold with inserts in Embodiment 1 of this application is as follows: Before die casting, insert 3 is fitted onto the insertion rod section 211 of the fixed insertion rod 21, with one end of insert 3 abutting against the inner wall of mold cavity 13; then, positioning block 22 is screwed onto connecting rod section 212, with positioning block 22 abutting against the inner bottom wall of limiting groove 31, thus achieving axial positioning of insert 3. After mold closing, molten metal is poured into mold cavity 13 through pouring pipe 14. During the filling process, positioning block 22, with its preset heat capacity and the protection of delayed melting layer, maintains structural integrity during the filling stage, maintaining axial positioning of insert 3; the molten metal quickly forms a solidified constraint shell on the outer periphery of insert 3, replacing positioning block 22 and taking over the constraint function of insert 3. After pouring, the mold is kept closed, and the residual heat of the casting is used to gradually and completely melt and disappear during the heat preservation stage, with its material integrated into the casting matrix. After the heat preservation is completed, start the cooling process. After cooling is complete, open the mold, pull out the fixed rod 21 directly along the axial direction, and take out the casting.

[0046] Example 2

[0047] Embodiment 2 of this application provides a die-casting mold with inserts.

[0048] Reference Figure 5 and Figure 6 The difference between Embodiment 2 and Embodiment 1 lies in the different structural forms of the positioning block 22.

[0049] In this embodiment, the positioning block 22 includes a connecting ring 224 and a limiting ring 225 coaxially sleeved and fixed outside the connecting ring 224. The connecting ring 224 is a solid circular ring structure, sleeved on the connecting rod segment 212 of the fixed insertion rod 21. The connecting ring 224 can be detachably connected to the connecting rod segment 212 through threaded engagement or interference fit. The outer diameter of the connecting ring 224 is smaller than the outer diameter of the insertion rod segment 211, ensuring that when the limiting ring 225 of the positioning block 22 melts and the fixed insertion rod 21 is pulled out axially together with the connecting ring 224, the connecting ring 224 will not cause radial interference with the inner wall of the insert 3.

[0050] In this embodiment, the connecting ring 224 may also be made of the same low-melting-point material as the limiting abutment ring 225, so that it melts away together with the limiting abutment ring 225 during the heat preservation stage. In other embodiments, the connecting ring 224 may be made of mold steel or the same high-temperature resistant alloy as the fixing rod 21, with a melting point higher than the pouring temperature of the molten metal. It will not melt during the pouring and heat preservation stages and will be carried out together with the fixing rod 21 when it is pulled out.

[0051] The outer diameter of the limiting ring 225 is matched with the radial dimension of the groove opening of the limiting groove 31, so that the limiting ring 225 can form an axial abutment with the side wall of the limiting groove 31. The limiting ring 225 has a hollow structure, which is conducive to rapid melting during the heat preservation stage. The limiting ring 225 can also be a mesh woven structure, a perforated thin ring, or a honeycomb structure.

[0052] An annular neck 226 is integrally formed between the limiting ring 225 and the connecting ring 224. The cross-sectional area of ​​the annular neck 226 is the smallest area in the limiting ring 225, thus forming a weak point on the limiting ring 225. During the heat preservation stage, the annular neck 226, due to its smallest cross-section, is preferentially melted under the action of residual heat, causing the limiting ring 225 to separate from the connecting ring 224. After losing the support of the connecting ring 224, the limiting ring 225 can quickly and independently melt completely.

[0053] Example 3

[0054] Embodiment 3 of this application provides a die casting production process, which uses a die casting mold with inserts as described in Embodiment 1 or Embodiment 2.

[0055] Includes the following steps: S1: Before die casting begins, prepare a solid insert 3. The insert 3 can be a dense metal cylinder pre-made by forging or extrusion. Place the insert 3 onto the insertion rod section 211 of the fixed insert 21, so that one end of the insert 3 abuts against the inner wall of the mold cavity 13 of the mold body 1, achieving axial positioning of one end of the insert 3. Then, install the positioning block 22 onto the connecting rod section 212 of the fixed insert 21, fixing the positioning block 22 to the end of the connecting rod section 212 by screwing or snapping. The positioning block 22 snaps into the limiting groove 31 of the insert 3, and the positioning block 22 abuts against the side wall of the limiting groove 31, forming an axial limit for the insert 3.

[0056] S2: Close the first mold core 11 and the second mold core 12. After closing the mold, pour molten metal into the mold cavity 13 simultaneously through multiple injection chambers using the gating pipe 14. The molten metal gradually fills the molding injection cavity 131, covering the outer wall of the insert 3 and the positioning block 22.

[0057] During the filling stage, the positioning block 22 continuously provides axial restraint for the insert 3. After filling is completed, the surface of the insert 3 melts under the action of the high-temperature molten metal, achieving fusion between the insert 3 and the casting substrate. After the molten metal comes into contact with the outer wall of the insert 3 and the relatively cool inner wall of the mold, the temperature rapidly drops below the liquidus line, forming a solidified constraint shell on the outer periphery of the insert 3, where t3>t1. The solidified constraint shell forms radial clamping and axial friction restraint on the insert 3 from the outside, replacing the axial restraint function of the positioning block 22.

[0058] S3: After pouring is completed, maintain the closed-die state of the mold body 1. Keep the closed-die state and maintain the heat preservation time t, where the range of the heat preservation time t is 30 - 90 s. During the heat preservation stage, the latent heat of solidification released during the solidification process of the casting and the sensible heat remaining temperature of the molten metal continuously transfer heat to the positioning abutting block 22 through heat conduction.

[0059] Since the melting point of the material of the positioning abutting block 22 is lower than the pouring temperature of the molten metal, and the positioning abutting block 22 is designed as a hollow structure with a relatively small total mass and requires less heat for melting, the waste heat of the casting is sufficient to completely melt the positioning abutting block 22 within the heat preservation time. The complete melting time t2 of the positioning abutting block 22 satisfies the relationship of t1 < t3 < t2 ≤ t3 + t, that is, the positioning abutting block 22 completely melts and disappears only after the solidification shell has formed and taken over the limiting function.

[0060] S4: After the heat preservation ends, start the cooling treatment to solidify and cool the whole casting to the demolding temperature. The cooling treatment can be realized through the cooling pipes arranged in the mold body 1. Setting cooling pipes in the mold body 1 is an existing technology in the art and will not be elaborated here.

[0061] S5: After cooling is completed, perform the mold-opening treatment, move the moving mold away, so that the first mold core 11 and the second mold core 12 are separated. Axially extract the fixed plug 21. At this time, the low-melting-point part in the positioning abutting block 22 has completely melted and disappeared and merged into the casting. If the scheme where the connecting ring 224 in Embodiment 2 is made of a high-temperature-resistant material is adopted, the connecting ring 224 is axially taken out together with the fixed plug 21. After extracting the fixed plug 21, take out the casting, and the connecting ring 224 needs to be removed before the next die-casting.

[0062] After that, subsequent machining of the casting can be carried out as needed. Due to the use of the prefabricated insert 3 with a dense structure in the machining area of the casting, defects such as gas shrinkage holes are not likely to occur during machining, the machining quality is good, and the product yield rate is greatly improved.

[0063] The above are all the preferred embodiments of this application, and the protection scope of this application is not limited thereby. Therefore, all equivalent changes made according to the structure, shape, and principle of this application should be covered within the protection scope of this application.

Claims

1. A die-casting mold with inserts, characterized in that, include: The mold body (1) includes a first mold core (11) and a second mold core (12). After the first mold core (11) and the second mold core (12) are closed, a mold cavity (13) is formed inside the mold body (1). A fixed insert (21) is connected to the first mold core (11). One end of the fixed insert (21) extends toward the mold cavity (13) and is fitted with an insert (3). One end of the insert (3) is used to abut against the inner wall of the mold cavity (13), and the other end is provided with a limiting groove (31). The positioning block (22) is detachably connected to the end of the fixing rod (21) away from the first mold core (11), and the positioning block (22) is snapped into the limiting groove (31) to abut against the insert (3). The material of the positioning block (22) has a melting point lower than the pouring temperature of the molten metal, so that the positioning block (22) can melt and disappear under the residual heat of the casting after pouring; and the positioning block (22) has a hollow structure, so that the time from contact with the molten metal to complete melting of the positioning block (22) is greater than the time for the molten metal to form a solidified constraint shell on the outer periphery of the insert (3).

2. The die-casting mold with inserts according to claim 1, characterized in that, The outer surface of the positioning block (22) is provided with a delayed melting layer, the melting point of which is higher than the melting point of the positioning block (22) but not higher than the pouring temperature of the molten metal.

3. A die-casting mold with inserts according to claim 1, characterized in that, The fixed insert (21) includes a coaxial and interconnected insert rod segment (211) and a connecting rod segment (212). The insert rod segment (211) is used to insert into the insert (3). A part of the connecting rod segment (212) extends into the limiting groove (31). The positioning block (22) is sleeved on one end of the connecting rod segment (212) and is detachably connected to the connecting rod segment (212).

4. A die-casting mold with inserts according to claim 3, characterized in that, The positioning block (22) includes two mesh sheets (221) spaced apart along the axial direction of the fixed insert (21), a connecting cylinder (222) connected between the two mesh sheets (221), and several support rods (223); the connecting cylinder (222) is sleeved outside the connecting rod segment (212) and is detachably connected to the connecting rod segment (212).

5. A die-casting mold with inserts according to claim 3, characterized in that, The positioning block (22) includes a connecting ring (224) and a limiting ring (225) coaxially sleeved and fixed outside the connecting ring (224). The connecting ring (224) is a solid structure. The connecting ring (224) is detachably connected to the connecting rod segment (212). The outer diameter of the connecting ring (224) is smaller than the outer diameter of the plug-in rod segment (211). The limiting ring (225) is a hollow structure.

6. A die-casting mold with inserts according to claim 5, characterized in that, An annular constriction neck (226) is provided between the limiting abutment ring (225) and the connecting ring (224).

7. A die-casting mold with inserts according to claim 1, characterized in that, The mold cavity (13) includes a molding injection cavity (131) and a liquid inlet cavity. The liquid inlet cavity includes a plurality of injection channels (132) spaced apart. One end of the injection channel (132) is connected to the outside and the other end is connected to the molding injection cavity (131). The liquid inlet cavity is provided with a plurality of channels spaced apart around the molding injection cavity (131).

8. A die-casting mold with inserts according to claim 1, characterized in that, The insert (3) has a connecting groove (32) on its outer side wall, and the connecting groove (32) is annular.

9. A die-casting mold with inserts according to claim 1, characterized in that, The material of the positioning block (22) is compatible with molten metal metallurgy.

10. A die-casting production process, employing a die-casting mold with inserts as described in any one of claims 3-6, characterized in that, Includes the following steps: S1: Before die casting begins, prepare a solid insert (3), and fit the insert (3) onto the insertion rod section (211) of the fixed insert (21), so that one end of the insert (3) abuts against the inner wall of the mold body (1); then install the positioning block (22) onto the connecting rod section (212) of the fixed insert (21), and the positioning block (22) is inserted into the limiting groove (31) of the insert (3) to axially limit the insert (3); S2: Close the mold body (1), and then pour molten metal into the mold cavity (13). The molten metal gradually wraps around the insert (3) and the positioning block (22). The surface of the insert (3) is fused with the molten metal, and the molten metal forms a solidified constraint shell on the outer periphery of the insert (3). S3: After the casting is completed, keep the mold body (1) in the closed state and keep it warm for a preset time, and use the residual heat of the casting to completely melt the positioning block (22); S4: After the heat preservation is completed, start the cooling process to solidify the casting; S5: After cooling is complete, open the mold, pull out the fixing rod along the axial direction, and then take out the casting.

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