Aluminum alloy wheel low-pressure casting mold and casting method

Abstract

The invention relates to the technical field of metal casting, and discloses an aluminum alloy wheel low-pressure casting mold and a casting method.The aluminum alloy wheel low-pressure casting mold comprises a top mold, a side mold and a bottom mold, the top mold is provided with a top mold core, the top mold core comprises a left mold core, a right mold core, a front mold core and a rear mold core which are alternately arranged in the circumferential direction, and the left mold core and the right mold core are in sliding connection; first wedge-shaped faces are arranged on the left-right mold core and the front-back mold core, dovetail grooves are formed in the first wedge-shaped faces in the vertical direction, a center sliding block used for adjusting the top mold core is further included, dovetail protruding blocks corresponding to the dovetail grooves are arranged on the center sliding block, and the dovetail protruding blocks and the dovetail grooves are matched in an inserted mode and connected in a sliding mode. According to the method, the shape of the wheel blank rim is thickened without considering the draft angle, the operation of removing the thickened part of the rim through subsequent machining turning to form the concave rim is omitted, the workload of the machining procedure is reduced, the production efficiency is guaranteed, and the metal utilization rate is increased; meanwhile, the problem that internal defects of the wheel blank are exposed is avoided, and the wheel quality is guaranteed.

Description

Technical Field

[0001] The invention relates to the technical field of metal casting, and in particular to a low-pressure casting mold and a casting method for an aluminum alloy wheel. Background Art

[0002] Aluminum alloy wheels have significant advantages such as light weight, energy saving and fuel saving, durability, excellent heat dissipation performance, excellent control and comfort, etc., and have been widely recognized and used in the passenger car market. When aluminum alloy wheels are manufactured, in order to facilitate the adaptation of more vehicle models, the wheel back cavity design usually reserves the maximum space, making the angle of the rim line of some aluminum alloy wheels close to vertical, and even some aluminum alloy wheels have a concave rim line. This type of rim is called a concave rim in the industry (such as the attached Figure 1 as shown).

[0003] It is well known in the industry that during the casting process of aluminum alloy wheels, the wheel blank needs to have a certain process draft angle to enable the wheel blank to be demolded smoothly. In order to facilitate demolding of wheels with concave rim shapes, the wheel blank rim shape can only be thickened to meet the process requirements of the draft angle. Subsequently, the thickened rim part is removed by machining to form a concave rim. In the above manufacturing method, the rim part of the wheel blank needs to undergo a large amount of turning operations, which increases the workload of the machining process and restricts the improvement of production efficiency; and a large amount of turning operations will produce more aluminum by-products, reduce metal utilization, and increase production costs; at the same time, the dense layer on the surface of the wheel blank is processed away, which reduces the structural strength of the rim and easily exposes internal defects, affecting the quality of the wheel.

[0004] Based on this, developing a low-pressure casting mold and casting method for aluminum alloy wheels for application in actual production is an issue that needs to be solved urgently. Summary of the invention

[0005] The purpose of the present invention is to provide a low-pressure casting mold for an aluminum alloy wheel in view of the above problems, so as to solve the problems that when the existing low-pressure casting mold for a wheel is used for the production of wheels for vehicles with concave rims, the workload of the machining process is large, the production efficiency is low, the metal utilization rate is low, the production cost is high, and the wheel quality cannot be effectively guaranteed.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is: A low-pressure casting mold for an aluminum alloy wheel comprises a top mold, a side mold and a bottom mold, wherein the top mold is provided with a top mold core as a rim molding structure, the top mold core comprises left and right mold cores and front and rear mold cores alternately arranged in a circumferential direction, the left and right mold cores and the front and rear mold cores are slidably connected, the left and right mold cores and the front and rear mold cores are provided with a first wedge-shaped surface, the first wedge-shaped surface is inclined outward from bottom to top, a dovetail groove is vertically provided on the upper edge of the first wedge-shaped surface, and a central slider for adjusting the top mold core is also included, a dovetail protrusion is provided on the central slider corresponding to the dovetail groove, and the dovetail protrusion is plug-fitted with the dovetail groove and slidably connected.

[0007] Preferably, a driving mechanism is provided corresponding to the center slider for adjusting the lifting and lowering of the center slider, the driving mechanism includes a power motor fixedly connected to the die-casting machine, the output end of the power motor is connected to a ball screw, a through screw hole is provided on the center slider corresponding to the ball screw, and the ball screw is threadedly connected to the through screw hole.

[0008] Preferably, the top mold is fixedly connected to the top mold plate, and the top mold core is horizontally slidably connected to the top mold plate. A guide groove is provided on the top mold plate, and guide keys are respectively provided at the top ends of the left and right cores and the front and rear cores corresponding to the guide grooves. The left and right cores and the front and rear cores are slidably matched with the guide keys through the guide grooves.

[0009] Preferably, the mold also includes a push rod for ejecting and demolding the wheel blank, the upper end of the push rod is connected to the push rod plate, the lower end of the push rod passes through and is slidably connected to the top template, the driving mechanism is connected to the push rod plate in a transmission manner, the ball screw is a forward and reverse screw, and the threads at its upper and lower ends have opposite rotation directions. A threaded hole is opened on the push rod plate corresponding to the upper end of the ball screw, the upper end of the ball screw is screwed into the threaded hole, and the lower end of the ball screw passes through the top template and is screwed into the through screw hole of the center slider.

[0010] Preferably, the pitch of the thread at the upper end of the ball screw is smaller than the pitch of the thread at the lower end thereof.

[0011] Preferably, the left and right core structures are crescent-shaped as a whole, and the front and rear cores are trapezoidal in structure as a whole. The waists of the trapezoidal structures of the front and rear cores and the inner sides of the crescent-shaped structures of the left and right cores are provided with second wedge-shaped surfaces correspondingly, and the front and rear cores and the left and right cores are slidably connected via the second wedge-shaped surfaces.

[0012] Preferably, the inclination angle of the first wedge surface of the front and rear cores is greater than the inclination angle of the first wedge surface of the left and right cores, so that the retraction speed of the front and rear cores is greater than the retraction speed of the left and right cores.

[0013] Preferably, the upper end of the push rod passes through the push rod plate, a return block is provided at the top of the push rod, a stop block is provided in the middle of the push rod, and the stop block is provided between the top template and the push rod plate.

[0014] Preferably, the stopper is positionally adjustable and connected to the ejector rod, so that the distance of the ejector rod's idle stroke is adjustable.

[0015] A casting method using the above casting mold comprises the following steps: S1. Mold closing step: the top mold, the side mold and the bottom mold are molded together to form a cavity for casting a wheel blank. During this process, the center slider on the top mold moves downward, and the dovetail protrusion on the center slider slides with the dovetail grooves on the left and right cores and the front and rear cores, and drives the left and right cores and the front and rear cores to be in an open state. At this time, the left and right cores and the front and rear cores are surrounded to form a molding structure corresponding to the rim part of the wheel blank, completing the mold closing action; S2. Mold opening step: after the wheel blank is cast, the side mold is opened, the top mold rises and carries the wheel blank away from the bottom mold, completing the mold opening action; S3. Demolding step: the center slider on the top mold moves upward, and the dovetail protrusion slides with the dovetail groove on the first wedge surface, driving the left and right cores and the front and rear cores to translate inward, so that the radial size of the top mold core shrinks, separates from the rim part of the wheel blank, and avoids the space where the concave rim interferes with the demolding of the top mold core, thus completing the demolding action. The beneficial effects of the present invention are: In the present invention, the top mold core that is separately arranged is slidably connected with the dovetail protrusion of the center slider through the dovetail groove provided on the first wedge surface, so that the peripheral volume of the top mold core can be adjusted. When the cast wheel blank is a concave rim that does not meet the process requirements of the draft angle, the left and right cores and the front and rear cores can be translated inward to achieve the overall inward shrinkage of the top mold core in the circumferential direction, and avoid the space where the concave rim interferes with the demolding of the top mold core, so that the core shrinkage and demolding of the top mold can be completed smoothly. The present invention thickens the wheel blank rim shape without considering the draft angle, eliminates the operation of removing the thickened part of the rim through subsequent machining to form a concave rim, reduces the workload of the machining process, ensures production efficiency and improves metal utilization; at the same time, it avoids the problem of machining off the dense layer on the surface of the wheel blank and exposing internal defects, and ensures the structural strength of the rim.

[0016] The configuration of the power mechanism in the present invention can simultaneously drive the ejector core to complete the retracting and opening actions and the continuous actions of the ejector rod ejecting the wheel blank through a set of power systems, which simplifies the power configuration of the mold, facilitates the inspection and maintenance of the mold, and saves the assembly space of the mold, is beneficial to the heat dissipation of the mold, and is convenient for the layout of water cooling and air cooling pipelines, as well as process adjustment and improvement. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0018] Figure 1 It is a schematic diagram of the structure of the concave rim of the wheel blank.

[0019] Figure 2 It is a structural schematic diagram of the mold clamping state of the present invention.

[0020] Figure 3 It is a structural schematic diagram of the mold opening state of the present invention.

[0021] Figure 4 It is a structural schematic diagram of the demoulding state of the present invention.

[0022] Figure 5 It is a schematic diagram of the three-dimensional structure of the left and right cores in the present invention.

[0023] Figure 6 It is a schematic diagram of the three-dimensional structure of the front and rear cores in the present invention.

[0024] Figure 7 It is a schematic diagram of the three-dimensional structure of the central slider in the present invention.

[0025] Figure 8 It is a top view of the top mold core in the open state in the present invention.

[0026] Fig. 9 It is a top view of the top mold core in the retracted state in the present invention.

[0027] In the figure: 10--top mold; 11--left and right cores; 12--front and rear cores; 13--center slider; 131--dovetail protrusion; 132--through screw hole; 14--first wedge surface; 141--dovetail groove; 15--power motor; 16--ball screw; 17--guide key; 18--second wedge surface; 20--side mold; 30--bottom mold; 40--top mold plate; 41--guide slide groove; 50--top rod plate; 51--top rod; 511--return block; 512--stop block; 52--threaded hole. DETAILED DESCRIPTION

[0028] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0029] like Figure 1-9As shown, a low-pressure casting mold for an aluminum alloy wheel includes a top mold 10, a side mold 20 and a bottom mold 30. The top mold 10 is provided with a top mold core as a rim molding structure. The top mold core is a split structure including a left and right core 11 and a front and rear core 12. The left and right cores 11 and the front and rear cores 12 are alternately arranged in the circumferential direction, and the left and right cores 11 and the front and rear cores 12 are slidably connected. A central slider 13 is provided corresponding to the top mold core for adjusting the position of the top mold core. Specifically, a first wedge-shaped surface 14 is provided on the left and right cores 11 and the front and rear cores 12. The first wedge-shaped surface 14 is inclined outward from bottom to top. A dovetail groove 141 is vertically provided on the first wedge-shaped surface 14. A dovetail protrusion 131 is provided on the central slider 13 corresponding to the dovetail groove 141. The dovetail protrusion 131 is plug-fitted and slidably connected with the dovetail groove 141. The vertical lifting movement of the center slider 13 can drive the left and right cores 11 and the front and rear cores 12 to move back and forth in the horizontal direction, thereby forming the movement of the left and right cores 11 and the front and rear cores 12 to shrink and open, thereby realizing the core shrinking and demoulding of the wheel blank.

[0030] During casting, the center slider 13 is located at the bottom of the top mold 10, and the dovetail protrusion 131 on the center slider 13 slides with the dovetail groove 141 on the left and right cores 11 and the front and rear cores 12, and drives the left and right cores 11 and the front and rear cores 12 to be in an open state. At this time, the left and right cores 11 and the front and rear cores 12 are combined to form a molding structure corresponding to the rim of the wheel blank. The top mold 10, the side mold 20 and the bottom mold 30 are combined to form a mold cavity for casting the wheel blank, and then the wheel blank casting is obtained through processes such as aluminum liquid filling, cooling and pressure holding. During demolding, the side mold 20 is opened, the top mold 10 is raised, and the wheel blank is separated from the bottom mold 30. At this time, the center slider 13 moves upward, and the dovetail protrusion 131 slides with the dovetail groove 141 on the first wedge surface 14, driving the left and right cores 11 and the front and rear cores 12 to translate inward, so that the radial size of the top mold core shrinks, separates from the rim part of the wheel blank, and avoids the space where the concave rim interferes with the demolding of the top mold core, thus successfully completing the demolding action of the wheel blank.

[0031] In this embodiment, the top mold core that is separately set is slidably connected with the dovetail protrusion 131 of the center slider 13 through the dovetail groove 141 opened on the first wedge surface 14, so that the outer volume of the top mold core can be adjusted. When the cast wheel blank is a concave rim and does not meet the process requirements of the draft angle, the left and right cores 11 and the front and rear cores 12 are translated inward to smoothly complete the core shrinking and demolding of the top mold 10. In this embodiment, there is no need to thicken the wheel blank rim shape to meet the process requirements of the draft angle, and the operation of removing the thickened part of the rim through subsequent machining to form a concave rim is eliminated, which reduces the workload of the machining process, ensures production efficiency and improves metal utilization; at the same time, it avoids the problem of machining off the dense layer on the surface of the wheel blank and exposing internal defects, ensuring the structural strength of the rim.

[0032] As a preferred embodiment, a driving mechanism is provided corresponding to the central slider 13, which is used for the lifting and lowering adjustment of the central slider 13 to realize the automatic core shrinking action of the top mold core. The driving mechanism includes a power motor 15 fixedly connected to the die casting machine, and the output end of the power motor 15 is connected to a ball screw 16. A through screw hole 132 is provided on the central slider 13 corresponding to the ball screw 16, and the ball screw 16 is screwed to the through screw hole 132. The power motor 15 drives the ball screw 16 to rotate forward and reverse, driving the central slider 13 to realize the lifting and lowering movement, thereby forming the inward shrinking or opening action of the top mold core.

[0033] Preferably, the top mold 10 is fixedly connected to the top mold plate 40, and the top mold core is horizontally slidably connected to the top mold plate 40. Specifically, a guide slot 41 is provided on the top mold plate 40, and guide keys 17 are respectively provided at the top ends of the left and right cores 11 and the front and rear cores 12 corresponding to the guide slots 41. The left and right cores 11 and the front and rear cores 12 achieve smooth horizontal movement through the sliding cooperation between the guide slots 41 and the guide keys 17, thereby ensuring the movement accuracy.

[0034] Preferably, the mold further comprises a push rod 51 for ejecting the wheel blank from the mold, the upper end of the push rod 51 is connected to the push rod plate 50, and the lower end of the push rod 51 penetrates and is slidably connected to the top mold plate 40. During demoulding, the top mold plate 40 drives the push rod 51 downward, so that the lower end of the push rod 51 penetrates the top mold 10 and presses against the wheel blank, and the top mold plate 40 continues to move downward, driving the push rod 51 to push the wheel blank away from the top mold 10, thereby completing the demoulding of the casting.

[0035] Furthermore, in order to save power configuration, the driving mechanism is connected to the ejector plate 50, and a set of power configuration is used to realize the continuous action of mold core shrinking and demolding and ejection of the ejector 51. Specifically, the ball screw 16 is a forward and reverse screw, and the threads at its upper and lower ends have opposite rotation directions. A threaded hole 52 is opened on the ejector plate 50 corresponding to the upper end of the ball screw 16. The upper end of the ball screw 16 is screwed to the threaded hole 52, and the lower end of the ball screw 16 passes through the ejector plate 40 and is screwed to the through screw hole 132 of the center slider 13. When the mold is closed, Figure 2 As shown, the power mechanism drives the ball screw 16 to rotate forward, and the lower end of the ball screw 16 drives the central slider 13 downward to drive the left and right cores 11 and the front and rear cores 12 to open. At the same time, the upper end of the ball screw 16 drives the ejector plate 50 upward and drives the ejector 51 upward away from the casting cavity; when demolding, as shown in FIG. Figure 4 As shown, the ball screw 16 reverses, and its lower end drives the central slider 13 upward, driving the ejector core to retract and separate from the wheel blank. At the same time, the upper end of the ball screw 16 drives the ejector plate 50 downward, driving the ejector 51 downward to eject the wheel blank from the ejector mold 10. In this embodiment, the power mechanism can simultaneously drive the ejector core to complete the retracting and opening actions and the ejector 51 to eject the wheel blank, simplifying the power configuration of the mold, facilitating inspection and maintenance operations, saving assembly space for the mold, facilitating heat dissipation of the mold, and facilitating the layout of water cooling and air cooling pipelines to improve the casting process.

[0036] Preferably, the pitch of the upper thread of the ball screw 16 is smaller than the pitch of the lower thread, so that the downward speed of the ejector plate 50 is lower than the upward speed of the center slider 13, so as to meet the requirement of a smaller stroke of the ejector 51 relative to the center slider 13. At the same time, the smaller pitch of the upper end of the ball screw 16 can provide a more linear thrust for the ejector 51, ensuring the stability of the wheel blank ejection action. More preferably, the pitch of the upper thread of the ball screw 16 is less than 50% of the pitch of the lower thread.

[0037] Preferably, if Figure 5-9 As shown, the left and right cores 11 are in a crescent-shaped structure as a whole, and the front and rear cores 12 are in a trapezoidal structure as a whole. The waist of the trapezoidal structure of the front and rear cores 12 and the inner side of the crescent-shaped structure of the left and right mold cores are provided with a second wedge-shaped surface 18 corresponding to each other, and the front and rear cores 12 are slidably connected with the left and right mold cores through the second wedge-shaped surface 18. During demoulding, the left and right cores 11 and the front and rear cores 12 slide inwardly along the second wedge-shaped surface 18 at the same time under the drive of the central slider 13, so that the radial dimension of the top mold core is shrunk as a whole, and the active demoulding of the rim part of the top mold 10 is realized.

[0038] Preferably, the inclination angle of the first wedge surface 14 of the front and rear cores 12 is greater than the inclination angle of the first wedge surface 14 of the left and right cores 11, so that the retraction speed of the front and rear cores 12 is greater than the retraction speed of the left and right cores 11, avoiding interference problems when the components move, ensuring the stability of the retraction and opening actions of the top mold core, and at the same time reducing the processing accuracy requirements of each component, saving mold processing and manufacturing costs.

[0039] Preferably, the upper end of the ejector rod 51 passes through the ejector rod plate 50, a return block 511 is provided at the top of the ejector rod 51, a stop block 512 is provided in the middle of the ejector rod 51, and the stop block 512 is provided between the ejector mold plate 40 and the ejector rod plate 50. When closing the mold, the ejector rod plate 50 moves upward and contacts the return block 511, driving the ejector rod 51 to move upward and return synchronously; when demolding, the ejector rod plate 50 moves downward, and when it contacts the stop block 512, it pushes the ejector rod 51 to move synchronously to eject the wheel blank. The implementation method of this city provides a return block 511 and a stop block 512, so that the ejector rod plate 50 drives the ejector rod 51 to move with a certain distance of idle travel, further improving the coordination of the ejector mold core and the ejector rod 51.

[0040] Furthermore, the stopper 512 is connected to the ejector rod 51 in an adjustable manner, so that the idle stroke distance of the ejector rod 51 is adjustable, so as to facilitate mold debugging. The present invention also provides a casting method based on the above-mentioned aluminum alloy wheel low-pressure casting mold, the method comprising the following steps: S1. Mold closing step: the top mold 10, the side mold 20 and the bottom mold 30 are molded together to form a cavity for casting a wheel blank. During this process, the center slider 13 on the top mold 10 moves downward, and the dovetail protrusion 131 on the center slider 13 slides with the dovetail groove 141 on the left and right cores 11 and the front and rear cores 12, and drives the left and right cores 11 and the front and rear cores 12 to be in an open state. At this time, the left and right cores 11 and the front and rear cores 12 are surrounded to form a molding structure corresponding to the rim part of the wheel blank, and the mold closing action is completed; S2 mold opening step, after the wheel blank is cast, the side mold 20 is opened, the top mold 10 is raised and carries the wheel blank out of the bottom mold 30, completing the mold opening action; S3. Demolding step: the center slider 13 on the top mold 10 moves upward, and the dovetail protrusion 131 slides with the dovetail groove 141 on the first wedge surface 14, driving the left and right cores 11 and the front and rear cores 12 to translate inward, so that the radial dimension of the top mold core shrinks, separates from the rim part of the wheel blank, and avoids the space where the concave rim interferes with the demolding of the top mold core, thus completing the demolding action.

[0041] When producing wheels with concave rims, this casting method thickens the rim shape of the wheel blank without considering the draft angle, eliminating the operation of removing the thickened part of the rim through subsequent machining to form the concave rim, reducing the workload of the machining process, ensuring production efficiency and improving metal utilization; at the same time, it avoids machining away the dense layer on the surface of the wheel blank and exposing internal defects, thereby ensuring the structural strength of the rim.

[0042] Preferably, the step S1 also includes: when the mold is closed, the power mechanism drives the ball screw 16 to rotate forward, and the lower end of the ball screw 16 drives the center slider 13 downward to drive the left and right cores 11 and the front and rear cores 12 to open. At the same time, the upper end of the ball screw 16 drives the ejector plate 50 upward and drives the ejector 51 upward away from the casting cavity.

[0043] Preferably, the step S3 also includes: when demolding, the ball screw 16 reverses, and its lower end drives the central slider 13 upward, driving the ejector mold core to retract and separate from the wheel blank; at the same time, the upper end of the ball screw 16 drives the ejector plate 50 downward, driving the ejector 51 downward to eject the wheel blank from the ejector mold 10.

[0044] In the above casting method, the power mechanism can simultaneously drive the ejector core to complete the retraction and opening actions and the ejector rod 51 to eject the wheel blank, which simplifies the power configuration of the mold, facilitates inspection and maintenance operations, saves mold assembly space, is beneficial to mold heat dissipation, and facilitates the layout of water cooling and air cooling pipelines to improve the casting process. The above disclosure is only a specific embodiment of the present invention, but the present invention is not limited thereto. For ordinary technicians in this field, without departing from the principle of the present invention, any modifications made should be deemed to belong to the protection of the present invention.

Claims

1. A low-pressure casting mold for an aluminum alloy wheel, comprising a top mold (10), a side mold (20) and a bottom mold (30), characterized in that: The top mold (10) is provided with a top mold core as a rim molding structure, the top mold core comprising left and right mold cores (11) and front and rear mold cores (12) arranged alternately in the circumferential direction, the left and right mold cores (11) and the front and rear mold cores (12) being slidably connected to each other, the left and right mold cores (11) and the front and rear mold cores (12) being provided with first wedge-shaped surfaces (14), the first wedge-shaped surfaces (14) being inclined outward from bottom to top, and a dovetail groove (141) being vertically provided on the first wedge-shaped surfaces (14), and further comprising a central slider (13) for adjusting the top mold core, the central slider (13) being provided with a dovetail protrusion (131) corresponding to the dovetail groove (141), the dovetail protrusion (131) being plug-fitted and slidably connected to the dovetail groove (141).

2. The low-pressure casting mold for an aluminum alloy wheel according to claim 1, characterized in that: A driving mechanism is provided corresponding to the central slider (13) for adjusting the lifting and lowering of the central slider (13), the driving mechanism comprising a power motor (15) fixedly connected to the die-casting machine, the output end of the power motor (15) being connected to a ball screw (16), a through screw hole (132) being provided on the central slider (13) corresponding to the ball screw (16), and the ball screw (16) being screwed to the through screw hole (132).

3. The low-pressure casting mold for an aluminum alloy wheel according to claim 1, characterized in that: The top mold (10) is fixedly connected to the top mold plate (40), and the top mold core is horizontally slidably connected to the top mold plate (40). A guide slot (41) is provided on the top mold plate (40), and guide keys (17) are respectively provided at the top ends of the left and right mold cores (11) and the front and rear mold cores (12) corresponding to the guide slots (41). The left and right mold cores (11) and the front and rear mold cores (12) are slidably matched with the guide keys (17) through the guide slots (41).

4. The low-pressure casting mold for an aluminum alloy wheel according to claim 2, characterized in that: The mold further comprises a push rod (51) for ejecting and demoulding the wheel blank, the upper end of the push rod (51) being connected to a push rod plate (50), the lower end of the push rod (51) penetrating and slidably connected to a top mold plate (40), the driving mechanism being transmission-connected to the push rod plate (50), the ball screw (16) being a forward and reverse rotating screw, the threads at the upper and lower ends of which are in opposite directions, a threaded hole (52) being provided on the push rod plate (50) corresponding to the upper end of the ball screw (16), the upper end of the ball screw (16) being screwed to the threaded hole (52), and the lower end of the ball screw (16) penetrating the top mold plate (40) and being screwed to a through screw hole (132) of a center slider (13).

5. The low-pressure casting mold for an aluminum alloy wheel according to claim 4, characterized in that: The pitch of the thread at the upper end of the ball screw (16) is smaller than the pitch of the thread at the lower end thereof.

6. The low-pressure casting mold for an aluminum alloy wheel according to claim 1, characterized in that: The left and right mold cores (11) are in a crescent-shaped structure as a whole, and the front and rear mold cores (12) are in a trapezoidal structure as a whole. The waist of the trapezoidal structure of the front and rear mold cores (12) and the inner side of the crescent-shaped structure of the left and right mold cores are provided with second wedge-shaped surfaces (18) correspondingly, and the front and rear mold cores (12) and the left and right mold cores are slidably connected via the second wedge-shaped surfaces (18).

7. The low-pressure casting mold for an aluminum alloy wheel according to claim 1, characterized in that: The first wedge-shaped surfaces (14) of the front and rear cores (12) have an inclination angle greater than the inclination angle of the first wedge-shaped surfaces (14) of the left and right cores (11), so that the retraction speed of the front and rear cores (12) is greater than the retraction speed of the left and right cores (11).

8. The low-pressure casting mold for an aluminum alloy wheel according to claim 4, characterized in that: The upper end of the push rod (51) passes through the push rod plate (50), a return block (511) is provided at the top of the push rod (51), a stop block (512) is provided in the middle of the push rod (51), and the stop block (512) is provided between the top template (40) and the push rod plate (50).

9. The low-pressure casting mold for an aluminum alloy wheel according to claim 8, characterized in that: The stopper (512) is positionally adjustable and connected to the push rod (51), so that the distance of the idle stroke of the push rod (51) is adjustable.

10. A casting method using the aluminum alloy wheel low-pressure casting mold according to claim 1, characterized in that: The steps include: S1. A mold closing step, in which the top mold (10), the side mold (20) and the bottom mold (30) are closed to form a mold cavity for casting a wheel blank, the center slider (13) on the top mold (10) moves downward, the dovetail protrusion (131) on the center slider (13) slides with the dovetail groove (141) on the left and right cores (11) and the front and rear cores (12), and drives the left and right cores (11) and the front and rear cores (12) to be in an open state, at which time the left and right cores (11) and the front and rear cores (12) are closed to form a molding structure corresponding to the rim portion of the wheel blank, and the mold closing action is completed; S2. Mold opening step: after the wheel blank is cast, the side mold (20) is opened, the top mold (10) is raised and carries the wheel blank out of the bottom mold (30), completing the mold opening action; S3. Demolding step: the center slider (13) on the top mold (10) moves upward, and the dovetail protrusion (131) slides with the dovetail groove (141) on the first wedge surface (14), driving the left and right cores (11) and the front and rear cores (12) to move inward, so that the radial size of the top mold core shrinks, separates from the rim portion of the wheel blank, and avoids the space where the concave rim interferes with the demolding of the top mold core, thereby completing the demolding action.

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