A method of casting a vehicle caliper

Abstract

The application relates to a casting method of an automobile caliper, and belongs to the casting technical field. The casting method comprises the following steps: preparing a sand core assembly, preparing a salt core, preheating a mold, and spraying a coating on the surface of a forming cavity of the mold. The upper sand core is buckled to the lower sand core to fix the salt core to form a combined core, the combined core is placed into a lower mold device of a casting mold, and the mold is closed. After an aluminum alloy solution is injected, the aluminum alloy solution is cooled to form a casting; the casting is taken out from the casting mold, a sand shaking process and a riser removal process are carried out; the salt core in the caliper blank is washed to form an oil passage; the caliper blank is subjected to heat treatment, and the production of the automobile caliper is completed. The sand core assembly and the salt core form the combined core, the combined core has the high-temperature structural stability of the sand core assembly, can have the effect that the salt core forms a smooth wall surface at the built-in oil passage of the caliper blank, the salt core has the easy cleaning property and no sand particle residue at the built-in oil passage, and the oil passage has high consistency in connection.

Description

Technical Field

[0001] This invention relates to the field of casting technology, and more particularly to a casting method for automotive calipers. Background Technology

[0002] With the development of the automotive industry, caliper assemblies have become an important component of the braking system in vehicles, especially in high-horsepower vehicles where fixed calipers are used. Fixed calipers have multiple pistons arranged on both sides of the brake disc. During operation, brake fluid is distributed to the pistons through lines on the caliper body. The pistons push the brake pads to clamp the brake disc, thus achieving immediate braking. Existing automotive calipers are manufactured using gravity casting molds, with the internal hydraulic lines and cylinder space formed using sand core molding. For example, publication number CN104791401A discloses a disc brake caliper body manufactured using sand casting with an iron mold and its production method.

[0003] Fixed automotive calipers have internal hydraulic passages for the movement of pistons on both sides. These passages need to be integrally molded during the caliper casting process. However, automotive calipers manufactured using sand core casting not only have a large surface roughness in their internal hydraulic passages, but also face significant challenges in cleaning the corresponding areas of the hydraulic passages. If residual sand particles from these areas detach and enter the pistons, there is a risk of damage to the caliper assembly. Therefore, improvements are needed. Summary of the Invention

[0004] To overcome the problems existing in related technologies, this invention provides a casting method for automotive calipers, which solves the technical problems of large roughness of the internal oil passages, high cleaning difficulty, and sand residue in sand core casting.

[0005] According to a first aspect of the present invention, a method for casting automotive calipers is provided, the casting method comprising:

[0006] Fabricate sand core components, which include complementary lower and upper sand cores;

[0007] The salt core is manufactured, and the salt core includes a cylinder body and oil passage pipes distributed at both ends of the cylinder body. The oil passage pipes are curved in a cylindrical shape, and the two ends of the oil passage pipes intersect with the two sides of the cylinder body respectively.

[0008] The mold is preheated, and a coating is sprayed onto the surface of the mold cavity.

[0009] To fabricate the composite core, the salt core is removed from the heating equipment at the heat preservation temperature. The cylinder body is embedded with the lower sand core, and then the upper sand core is fastened to the lower sand core to fix the cylinder body. The oil passage pipe extends out from both ends of the composite core, and the two sides of the cylinder body extend beyond the sand core assembly.

[0010] After the combined core is put into the lower mold device of the casting mold, the mold is closed, and both ends of the salt core and the oil channel pipe are suspended in the forming cavity of the casting mold;

[0011] After the aluminum alloy solution is injected, the casting is formed by cooling;

[0012] The casting is taken out of the casting mold, and the sand shaking process and the riser removal are performed to obtain the caliper blank;

[0013] The salt core in the caliper blank is washed to form an oil channel;

[0014] The caliper blank is heat treated to complete the production of the automobile caliper.

[0015] In an embodiment, the cylinder part includes two parallel intermediate columns and at least two connecting rods connecting the two intermediate columns;

[0016] The intermediate column includes an intermediate rod and a shaped end at both ends of the intermediate rod, the diameter of the shaped end is larger than the diameter of the intermediate rod, part of the shaped end is embedded in the sand core assembly, the end of the shaped end exceeds the sand core assembly, and the oil channel pipe intersects the end of the shaped end.

[0017] In an embodiment, the end of the shaped end has a radially protruding annular rib, the oil channel pipe intersects the annular rib, and the connecting rod connects the annular rib.

[0018] In an embodiment, the projection of the oil channel pipe on the plane where the two intermediate columns are located is in the shape of U, and at least part of the oil channel pipe is bent relative to the plane where the two intermediate columns are located.

[0019] In an embodiment, the method for manufacturing the salt core includes:

[0020] The salt core is heated, the heating temperature ranges from 400 degrees Celsius to 520 degrees Celsius, and the heating is maintained for 2.5 hours to 3.5 hours;

[0021] The salt core is cooled to a holding temperature and is held, wherein the thermal expansion coefficient of the salt core at the holding temperature and the thermal expansion coefficient of the sand core at the normal temperature are substantially the same.

[0022] In an embodiment, the lower sand core includes a lower matching surface, a lower embedded part, and a lower positioning groove recessed from the lower matching surface, the upper sand core includes an upper matching surface, an upper embedded part, and an upper positioning groove recessed from the upper matching surface, the lower matching surface and the upper matching surface are attached to each other, the lower embedded part and the upper embedded part are at least two bosses and grooves that are complementarily embedded, and the lower positioning groove and the upper positioning groove define the cylinder part.

[0023] In an embodiment, after the aluminum alloy solution is injected, the casting is formed by cooling, which includes:

[0024] The lower mold device is provided with at least one forming groove and pouring channels located on both sides of the forming groove, the pouring channels are provided with three intermediate molten pools in the flow direction and injection ports corresponding to each intermediate molten pool, the injection ports are arranged towards the direction of the sand core assembly and are misaligned with the cylinder body part.

[0025] In an embodiment, the aluminum alloy solution is cooled to form a casting after injection, including:

[0026] The cooling mechanism is started to control the mold temperature at 360-400°C;

[0027] The mold is controlled to maintain pressure for 350-370 seconds.

[0028] In an embodiment, the caliper blank is heat treated, including:

[0029] The caliper blank is solution treated at a heating temperature of 530-550°C for 5-8.5 hours;

[0030] The solution transfer time is controlled to be less than or equal to 30 seconds;

[0031] The caliper blank is aged at an aging temperature of 160-175°C for 6-7.5 hours.

[0032] In an embodiment, the salt core in the caliper blank is flushed, including:

[0033] The flushing medium is aligned to flush the salt core in the caliper blank;

[0034] The salt core in the caliper blank is dissolved, and the caliper blank forms corresponding oil passage and cylinder space.

[0035] The technical scheme provided by the embodiment of the present application can include the following beneficial effects: the sand core assembly and the salt core form a combined core, which has high-temperature structural stability of the sand core assembly and the effect of forming a smooth wall surface of the salt core at the built-in oil passage of the casting, and the salt core at the built-in oil passage also has the advantages of easy cleaning and no sand particle residue. The cylinder body part of the salt core is supported by the sand core assembly, which reduces the volume of the corresponding area of the salt core, thereby reducing the high-temperature deformation of the salt core, and the combined core has a convenient assembly structure. The salt core corresponds to the cylinder space and the built-in oil passage of the casting, and the oil passage has high consistency. BRIEF DESCRIPTION OF DRAWINGS

[0036] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0037] Figure 1is a flow chart showing a casting method according to an embodiment.

[0038] Figure 2 is a structural schematic diagram of a combined core according to an embodiment.

[0039] Figure 3 is an exploded structural schematic diagram of a combined core according to an embodiment.

[0040] Figure 4 is a structural schematic diagram of a salt core according to an embodiment.

[0041] Figure 5 is a front structural schematic diagram of a salt core according to an embodiment.

[0042] Figure 6 is a schematic diagram of a combined core in a lower mold device according to an embodiment.

[0043] In the figure, the sand core assembly 10; the lower sand core 11; the lower mating surface 111; the lower positioning groove 112; the lower fitting part 113; the upper sand core 12; the upper mating surface 121; the upper positioning groove 122; the top recess 123; the triangular protrusion 124; the salt core 20; the oil channel pipe 21; the arc-shaped area 211; the bevel area 212; the elbow area 213; the middle column 22; the middle rod 221; the forming end 222; the annular protruding rib 2221; the connecting rod 23; the middle rod 231; the cylinder part 24; the lower mold device 30; the pouring channel 31; the middle melt pool 311; the injection inlet 312; the forming groove 32; the lateral channel 33; the side melt pool 331. DETAILED DESCRIPTION

[0044] In the description of the present application, it needs to be understood that if the terms "upper", "lower", "left", "right", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, therefore the terms describing the positional relationship in the drawings are only used for exemplary illustration, and cannot be understood as a limitation on the present application, for those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0045] As shown in Figures 1 to 3 The present application provides a casting method of an automobile caliper, the casting method comprising the following steps:

[0046] S101, a sand core assembly 10 is made, the sand core assembly 10 includes a lower sand core 11 and an upper sand core 12 which are complementary matched. The lower sand core 11 and the upper sand core 12 are two-part independent sand core structural members, a positioning cavity is formed at the matched part of the lower sand core 11 and the upper sand core 12, the outer peripheral wall of the sand core assembly 10 corresponds to the recessed area of the automobile caliper, and the recessed area of the automobile caliper is hereinafter referred to as a mounting cavity. Optionally, the sand core assembly 10 is made of coated sand.

[0047] S102, a salt core 20 is made, the salt core 20 includes a cylinder part 24 and oil passage pipes 21 which are distributed at both ends of the cylinder part 24, the oil passage pipes 21 are curved and columnar, and the two ends of the oil passage pipes 21 respectively intersect with the two sides of the cylinder part 24. The salt core 20 is used for forming the cylinder space of the castings and the built-in oil passage for the flow of brake oil, wherein the cylinder part 24 is used for forming the corresponding cylinder space, and the oil passage pipes 21 are used for forming the corresponding built-in oil passage.

[0048] After the salt core 20 and the sand core assembly 10 are completed, they need to be inspected, and the salt core 20 and the sand core assembly 10 are assembled to form a combined core.

[0049] S103, the mold is preheated, and paint is sprayed on the surface of the forming cavity of the mold. The mold is heated to be at a suitable casting temperature, and optionally, the mold is preheated by flame baking or using the waste heat of the mold production or by a heating coil.

[0050] S104, the combined core is made, the salt core 20 is taken out from the heating equipment at a holding temperature, the cylinder part 24 is embedded into the lower sand core 11, and then the upper sand core 12 is buckled to the lower sand core 11 to fix the cylinder part 24, the oil passage pipes 21 are taken out from both ends of the combined core, and the two sides of the cylinder part 24 exceed the sand core assembly 10. The salt core 20 needs to be stored in the heating equipment before casting processing, and the heating equipment heats the salt core 20, so that the thermal expansion coefficient of the salt core 20 and the thermal expansion coefficient of the sand core assembly 10 are basically the same or close to each other. In the casting process, the salt core 20 and the sand core assembly 10 expand uniformly when the metal liquid is poured, so as to improve the forming quality.

[0051] The lower sand core 11 is placed on a workbench, the salt core 20 is matched and placed on the lower sand core 11, and then the upper sand core 12 is buckled to the lower sand core 11. The matched part of the lower sand core 11 and the upper sand core 12 forms a recessed positioning cavity, and the cylinder part 24 is embedded and fixed in the positioning cavity. The cylinder part 24 of the salt core 20 is supported and limited by the sand core assembly 10, the volume of the salt core 20 exposed outside the sand core assembly 10 is reduced, so as to reduce the high-temperature deformation amount of the salt core 20, and the combined core has a convenient assembly structure.

[0052] S105, the combined core is put into the lower mold device 30 of the casting mold, and the two ends of the salt core 20 and the oil passage pipe 21 are suspended in the forming cavity of the casting mold. Specifically, the lower mold device 30 has a forming groove 32, and the lower sand core 11 is put into the forming groove 32, and the combined core is erected and connected to the lower mold device 30. The space between the combined core and the forming cavity can be injected with molten metal, and the molten metal forms a solid structure part corresponding to the casting.

[0053] S106, after the aluminum alloy solution is injected, the casting is formed by cooling; the salt core 20 is partially suspended outside the sand core assembly 10, the space in the forming cavity is filled with molten metal, and the combined core is wrapped by the molten metal. Wherein, the molten metal is cooled to form the casting, preferably, the mold is a gravity casting mold, so as to reduce the impact of the molten metal on the combined core, reduce the deformation amount of the combined core, especially reduce the deformation amount of the salt core 20.

[0054] S107, the casting is taken out from the casting mold, and the sand shaking process and the riser removal are performed to obtain the caliper blank. After the mold is opened, the casting is taken out, and the casting is vibrated by the sand shaking equipment to remove the coated sand corresponding to the sand core assembly 10. The salt core 20 in the middle part is broken or broken, so that the combined core part corresponding to the casting is hollow. Then, the riser and the handle part corresponding to the pouring channel 31 are cut off, so as to reserve the corresponding caliper blank.

[0055] S108, the remaining salt core 20 in the caliper blank is washed to form an oil passage. The caliper blank is washed by a washing equipment, specifically, the salt core 20 part in the caliper blank is washed by the washing equipment, wherein the salt core 20 corresponding to the built-in oil passage is washed by the washing equipment, and the salt core 20 in the caliper blank is dissolved in the washing process, so as to realize the penetration of the built-in oil passage, and the built-in oil passage prepared by the salt core 20 has high smoothness and does not leave sand.

[0056] S109, the caliper blank is heat treated to complete the production of the automobile caliper.

[0057] The sand core assembly 10 and the salt core 20 form a combined core, which has high temperature structure stability of the sand core assembly 10 and can form a smooth wall surface at the built-in oil passage of the caliper blank, and the salt core 20 has easy cleaning and no sand residue at the built-in oil passage.

[0058] As shown in Figures 2 to 4 In an embodiment, the cylinder part 24 includes two parallel intermediate columns 22 and at least two connecting rods 23 connecting the two intermediate columns 22. The intermediate column 22 corresponds to the piston mounting part of the formed automobile caliper, and the connecting rod 23 connects the intermediate column 22, so that the cylinder part 24 forms a structure similar to a "mouth" character, a "day" character or a "eye" character.

[0059] For the convenience of the salt core 20 preparation, the salt core 20 and the sand core assembly 10 are assembled. The intermediate column 22 includes an intermediate rod 221 and a shaped end 222 at both ends of the intermediate rod 221, and the diameter of the shaped end 222 is larger than that of the intermediate rod 221. The shaped end 222 corresponds to the mounting position of the shaped piston, and the intermediate rod 221 connects the two shaped ends 222 into one body and is embedded in the positioning cavity defined in the sand core assembly 10 to constitute the peripheral positioning of the intermediate column 22. Part of the shaped end 222 is embedded in the sand core assembly 10 to constitute the axial positioning. Therefore, the intermediate column 22 can realize axial and peripheral positioning, and the sand core assembly 10 and the salt core 20 have high assembly precision. The shaped end 222 is embedded in the sand core assembly 10 to form a tight contact of the bonding surface, avoid the metal liquid from entering, and can form the side wall of the recessed area of the automobile caliper.

[0060] The end of the shaped end 222 exceeds the sand core assembly 10, and the oil channel pipe 21 intersects to the end of the shaped end 222. After the casting is completed, the end of the shaped end 222 is located in the casting, and after the sand shaking process of the casting is completed, part of the shaped end 222 and the oil channel pipe 21 are located in the casting, which need to be flushed and dissolved by a flushing device to obtain a relatively smooth wall surface and reduce the flow resistance of the oil liquid.

[0061] Optionally, the connecting rod 23 includes a middle rod 231 located between the two intermediate columns 22, and the middle rod 231 can be provided as a flat rod body.

[0062] In a preferred embodiment, the end of the shaped end 222 has a radially protruding annular rib 2221, the oil channel pipe 21 intersects the annular rib 2221, and the connecting rod 23 connects the annular rib 2221. The annular rib 2221 is an annular structure, the connecting rod 23 intersects the annular rib 2221, and correspondingly, an annular groove and a connecting channel corresponding to the annular groove are formed in the casting, which facilitates the oil liquid to pass through.

[0063] Further preferably, the shaped end 222 at each end has two annular ribs 2221, one of which is embeddedly connected with the sand core assembly 10, and the other is suspended, and the annular ribs 2221 and the connecting rod 23 are connected to form a continuous and connected channel structure, and correspondingly, the pistons on both sides of the automobile caliper are connected through the channel structure.

[0064] As Figures 3 to 5As shown, in one embodiment, the projection of the oil passage 21 onto the plane containing the two intermediate pillars 22 is U-shaped, and at least a portion of the oil passage 21 is bent relative to the plane containing the two intermediate pillars 22. The intermediate pillars 22 are arranged in parallel, and the plane containing the intermediate pillars 22 is referred to as the reference plane. The projection of the oil passage 21 onto the reference plane is U-shaped, thereby connecting the two ends of the intermediate pillars 22, so that the final internal oil passage of the casting can form a continuous oil passage connecting both sides. That is, an approximately annular flow oil passage is formed inside the casting.

[0065] In a direction perpendicular to the reference plane, the oil pipe 21 is bent and inclined relative to the reference plane to improve the structural strength and bending and torsional strength of the oil pipe 21, thereby maintaining the structural stability of the oil pipe 21. For example, on the midpoint perpendicular to the reference plane, the oil pipe 21 has an approximately V-shaped or C-shaped structure.

[0066] In one specific embodiment, the oil passage 21 includes a U-shaped bend 213, arc-shaped areas 211 distributed at both ends of the bend 213, and a beveled area 212 bending from the arc-shaped areas 211. The beveled areas 212 intersect at the forming end 222. The extending direction of the beveled areas 212 is inclined relative to the plane where the two intermediate pillars 22 are located. The bend 213 intersects the plane where the two intermediate pillars 22 are located. The projections of the bend 213, arc-shaped areas 211, and beveled areas 212 onto the reference plane are approximately U-shaped. On the midpoint plane perpendicular to the reference plane, the oil passage 21 has an approximately V-shaped structure.

[0067] In a further preferred embodiment, the inclined side region 212 is inclined downward toward the reference plane, the end of the bend region 213 protrudes upward toward the reference plane, and the arc region 211 is an arc-shaped surface to connect the inclined side region 212 and the bend region 213, which has high bending and torsional strength and high structural stability.

[0068] In one embodiment, the salt core 20 is fabricated in step S102, which includes the following steps:

[0069] like Figures 1 to 3 As shown, the salt core 20 is heated to a temperature range of 400°C to 520°C and held for 2.5 to 3.5 hours. Heating the salt core 20 allows it to be adapted for aluminum alloy casting mold production. The heating temperature can be adjusted according to the salt core 20; for example, it can be set to 400°C, 420°C, 460°C, or 520°C. The salt core 20 is held at the corresponding temperature for the corresponding duration to improve its structural stability.

[0070] After the salt core 20 is heated, the salt core 20 needs to be preheated or kept at a temperature before the salt core 20 and the sand core assembly 10 are combined to enter the mold, so as to improve the fluidity of the molten metal around the salt core 20. In this step, the salt core 20 is cooled to a temperature and kept at the temperature, and the thermal expansion coefficient of the salt core 20 at the temperature is substantially the same as the thermal expansion coefficient of the sand core at the normal temperature.

[0071] In this step, the temperature of the salt core 20 can be adjusted to adapt the expansion coefficient of the salt core 20 to the expansion coefficient of the sand core assembly 10, so that the expansion coefficients of the combined core are substantially the same, thereby keeping the expansion consistency of the combined core and improving the casting precision. In addition, the temperature of the salt core 20 is high, and the stability of the flow of the molten metal around the combined core can be kept. For example, the sand core assembly 10 is made of conventional coated sand material, and the temperature of the salt core 20 can be configured to be 100-120 degrees Celsius.

[0072] In step S101, the sand core assembly 10 is made, and the sand core assembly 10 clamps and fixes the salt core 20. In an embodiment, the lower sand core 11 includes a lower matching surface 111, a lower fitting part 113, and a lower positioning groove 112 recessed from the lower matching surface 111, the upper sand core 12 includes an upper matching surface 121, an upper fitting part, and an upper positioning groove 122 recessed from the upper matching surface 121, and the lower matching surface 111 and the upper matching surface 121 are attached to each other.

[0073] The lower sand core 11 and the upper sand core 12 are block structures, and the outer surfaces of the lower sand core 11 and the upper sand core 12 correspond to the cavity walls of the molding cavity. The lower fitting part 113 and the upper fitting part are at least two complementary fitting bosses and grooves, so that the fitting positions of the lower sand core 11 and the upper sand core 12 are accurate, and the assembly precision and consistency of the two are high. For example, the lower fitting part 113 is two recessed fitting counterbores, and the lower positioning groove 112 is located between the two fitting counterbores. The upper fitting part is two protruding fitting bosses, and the fitting bosses and the fitting counterbores are inserted and fitted. The lower fitting part 113 and the upper fitting part can not only complementarily fit and position, but also increase the strength of the lower positioning groove 112 and the upper positioning groove 122 for limiting the cylinder part 24.

[0074] Further preferably, the top of the upper sand core 12 includes a recessed top groove 123 and two protruding triangular bosses 124 on one side of the top groove 123. The top groove 123 can be positioned in cooperation with the upper mold device of the mold, and the thickness of the top of the upper sand core 12 can be reduced. The heights of the bosses on the two sides of the top groove 123 are different, which can change the flow direction of the molten metal in the cavity, and the molten metal wraps the salt core 20 from the two sides to the two sides of the molding cavity, so as to reduce the impact of the molten metal on the salt core 20.

[0075] In step S106, the aluminum alloy solution is injected and cooled to form a casting, wherein the mold includes a lower mold device 30 and an upper mold device, and the upper mold device and the lower mold device 30 are combined and matched.

[0076] The lower mold device 30 is provided with at least one forming groove 32, which is a groove structure, and the groove wall of the forming groove 32 is basically the same as the outer peripheral wall of the automobile caliper. The combined core is placed in the forming groove 32, and the lower sand core 11 and the lower mold device 30 are assembled and connected. The upper mold device and the upper sand core 12 are matched and positioned, so that the positioning connection can be performed. Among them, the oil channel pipe 21 of the salt core 20 is located in the forming cavity and is suspended, and forms two ends inside the casting after the metal liquid is poured.

[0077] As shown in Figures 1 to 3 , Figure 6 , the lower mold device 30 is provided with pouring channels 31 and lateral channels 33 on both sides of the forming groove 32, which can guide the metal liquid into the forming cavity. Among them, the pouring channel 31 and the lateral channel 33 are connected through the uniform injection port 312 to form an annular flow channel structure. The pouring channel 31 and the lateral channel 33 inject metal liquid from opposite sides, which can improve the filling efficiency of the metal liquid, especially in the gravity casting mold using multiple injection positions, which can improve the metal liquid flow and reduce the impact force on the combined core, thereby reducing the problem of deformation of the combined core under impact.

[0078] As preferred, the lower mold device 30 is configured with a double-cavity structure, which can produce two automobile calipers at the same time. The lateral channel 33 is provided with two, and the pouring channel 31 is located in the middle position to deliver the metal liquid to the two forming cavities.

[0079] Specifically, the pouring channel 31 is provided with three intermediate molten pools 311 and corresponding injection ports 312 for each intermediate molten pool 311 along the flow direction, and the injection port 312 is located away from the salt core 20 and is disposed towards the sand core assembly 10. The intermediate molten pool 311 is a concave molten pool structure, and the depth of the intermediate molten pool 311 is greater than the depth of the flow channel, so that the metal liquid can be buffered at the intermediate molten pool 311 and the shrinkage amount during the cooling process of the casting in the forming cavity can be compensated.

[0080] The three intermediate molten pools 311 correspond to the three injection ports 312 respectively, and the direction of the injection port 312 is towards the sand core assembly 10 and avoids directly impacting the salt core 20, thereby reducing the expansion amount of the salt core 20 and improving the stability of the casting forming.

[0081] The lateral channel 33 and the pouring channel 31 are distributed on both sides of the forming cavity, so as to fill the same forming cavity from both sides. Not only the filling time is short, but also the impact force on the combined core is reduced, and the impact force directions on both sides of the combined core are opposite, part of the impact force is offset, so that the deformation of the combined core can be reduced.

[0082] The lateral channel 33 is provided with three side edge melt pools 331 and side gates corresponding to each side edge melt pool 331, the side gates are arranged towards the sand core assembly 10 and are staggered with the cylinder body 24. The structure and principle of the lateral channel 33 and the pouring channel 31 are similar, the side edge melt pool 331 can cold shrink the automobile caliper part, the solidification time of the side edge melt pool 331 is longer than that of the forming cavity, which can improve the forming quality of the automobile caliper. The lateral channel 33 and the pouring channel 31 have the functions of flow channel and melt pool supplement, which greatly improves the forming effect of the automobile caliper.

[0083] As shown in Figures 1 to 3 Further, the upper die device is provided with a riser corresponding to the side edge melt pool 331 and the intermediate melt pool 311 to further prolong the cooling time of the corresponding area.

[0084] After the aluminum alloy solution is injected in step S106, the cooling forming is a casting, which specifically includes the following cooling steps:

[0085] The cooling mechanism is started to control the mold temperature at 360-400°C;

[0086] The mold pressure is controlled for 350-370 seconds.

[0087] The metal liquid is injected into the forming cavity from the lateral channel 33 and the pouring channel 31 respectively, and the filling is completed. The cooling mechanism cools the mold, which can shorten the cooling forming time of the metal liquid and avoid the influence of too fast cooling on the forming quality of the automobile caliper. The volume and weight of the automobile caliper can be adapted to different pressure holding time and mold temperature. The mold temperature can be controlled at one of 360°C, 380°C, 390°C and 400°C, and the mold pressure holding time is controlled at one of 350 seconds, 355 seconds, 360 seconds, 365 seconds and 370 seconds, so that the automobile caliper has stable forming quality.

[0088] The heat dissipation speed and temperature of the thick-walled aluminum alloy casting of the automobile caliper can avoid slow solidification caused by high temperature and prevent internal porosity caused by low temperature. The appropriate pressure holding time ensures that the intermediate melt pool 311 part can continue to supplement before the metal liquid completely solidifies.

[0089] After the mold is opened, the casting is taken out and the sand shaking process is performed, so that the corresponding part of the casting on the sand core assembly 10 is removed. Further, part of the salt core 20 can be removed by vibration fracture or by flushing medium to remove the corresponding part of the cylinder body 24.

[0090] Then, the excess material handle and riser of the casting are removed, and the caliper blank is obtained.

[0091] Further, the salt core 20 in the caliper blank is flushed, which includes the following steps:

[0092] The flushing medium is used to flush the salt core 20 in the caliper blank, and the salt core 20 in the caliper blank is dissolved, and the caliper blank forms corresponding oil passage and cylinder space. The salt core 20 can be dissolved in the flushing medium, so as to leave the oil passage and the cylinder space in the caliper blank. The cylinder space is used to install the piston, and the oil passage is used to flow the fluid, so that a smooth oil flow space can be realized.

[0093] The forming end 222 corresponds to the cylinder space, the connecting rod 23 and the oil passage pipe 21 correspond to the hole-shaped oil passage in the formed caliper blank, the forming end 222 corresponds to the counterbore-shaped cylinder space, the oil passage and the cylinder space form a fluid flow path similar to an annular shape, so that the piston installed in the cylinder space can be driven to move.

[0094] After the caliper blank is cleaned, deburring is performed, and then the caliper blank is subjected to heat treatment, and the heat treatment step includes:

[0095] The caliper blank is subjected to solid solution treatment, the heating temperature is 530-550°C, and the holding time is 5-8.5 hours; the solid solution treatment can make the caliper blank obtain a supersaturated solid solution, so as to improve the mechanical properties of the material. The heating temperature is 530°C, 540°C, or 550°C, and the holding time can be set to 5 hours, 6 hours, 6.5 hours, 7 hours, 8 hours, or 8.5 hours.

[0096] The solid solution transfer time is controlled to be less than or equal to 30 seconds; the caliper blank is taken out from the solid solution treatment furnace, and the solid solution transfer time is controlled to be within 30 seconds, so that the performance of the caliper blank reaches the best. For example, the solid solution transfer time is set to 20 seconds, 23 seconds, 25 seconds, 28 seconds, 30 seconds, etc. Controlling the solid solution transfer time minimizes the cooling delay after solid solution, avoids the alloy elements from being precipitated in advance due to temperature drop during the transfer process, destroys the “supersaturated solid solution” state, and ensures the subsequent aging strengthening effect.

[0097] The caliper blank is subjected to aging treatment, and the aging treatment temperature is 160-175°C, and the holding time is 6-7.5 hours. The aging treatment temperature of the caliper blank is set to 160°C, 163°C, 168°C, 170°C, 172°C and 175°C, so that the best performance state of the corresponding aluminum alloy casting can be achieved, and the hardness and strength of the material are high. The holding time under the corresponding aging treatment temperature can be 6 hours, 6.5 hours, 6.8 hours, 7 hours, 7.2 hours and 7.5 hours, which can ensure the complete precipitation of the strengthening phase and avoid the reduction of production efficiency caused by overaging, and the hardness, elastic modulus and strength of the caliper blank are significantly improved. Compared with low-temperature aging, the aging time can be shortened by 30%-50%. The aging treatment process scheme is suitable for automobile caliper thick-walled structural parts and aluminum alloy castings with medium and high strength requirements. For example, for a 2024 aluminum alloy thick-walled casting, the tensile strength after the process treatment is 420-460 MPa, the yield strength is 320-360 MPa, the hardness (HV) is 125-135, and the elongation is 8%-10%.

[0098] It is to be understood that the application is not limited to the precise construction that has been described above and shown in the accompanying drawings, and that various modifications and changes can be made by those skilled in the art without departing from the scope of the application. The application is intended to cover any adaptations or variations of the present application following in the spirit of the application and including those that are within the scope of the patent laws.

Claims

1. A casting method of an automobile caliper, characterized by, The casting method comprises: manufacturing a sand core assembly, the sand core assembly comprising a lower sand core and an upper sand core which are complementarily matched; manufacturing a salt core, the salt core comprising a cylinder part and oil passage pipes which are distributed at two ends of the cylinder part, the oil passage pipes being curved in a curve column shape, and the two ends of the oil passage pipes intersecting with two sides of the cylinder part respectively; preheating a mold and spraying paint on a forming cavity surface of the mold; manufacturing a combined core, the salt core being taken out from a heating device at a holding temperature, the cylinder part being embedded in the lower sand core, the upper sand core being buckled to the lower sand core to fix the cylinder part, the oil passage pipes being penetrated from two ends of the combined core, and two sides of the cylinder part exceeding the sand core assembly; placing the combined core into a lower mold device of a casting mold and closing the mold, wherein the two ends of the salt core and the oil passage pipes are suspended in a forming cavity of the casting mold; injecting an aluminum alloy solution and cooling to form a casting; taking the casting out of the casting mold, performing sand shaking process and removing risers to obtain a caliper blank; flushing the salt core in the caliper blank to form oil liquid passages; performing heat treatment on the caliper blank to complete production of an automobile caliper.

2. The casting method according to claim 1, characterized by, The cylinder part comprises two intermediate columns which are arranged in parallel and at least two connecting rods which connect the two intermediate columns; The intermediate column comprises an intermediate rod and forming ends which are located at two ends of the intermediate rod, the forming ends have diameters which are greater than that of the intermediate rod, part of the forming ends are embedded in the sand core assembly, and the ends of the forming ends exceed the sand core assembly, and the oil passage pipes intersect with the ends of the forming ends.

3. The casting method according to claim 2, characterized in that, The ends of the forming ends have radially protruding annular ribs, the oil passage pipes intersect with the annular ribs, and the connecting rods connect the annular ribs.

4. The casting method according to claim 2, characterized by The projection of the oil passage pipes on the plane where the two intermediate columns are located is in a U shape, and at least part of the oil passage pipes are curved relative to the plane where the two intermediate columns are located.

5. The casting method according to claim 1, characterized by, The manufacturing of the salt core comprises: heating the salt core, the heating temperature ranges from 400 degrees Celsius to 520 degrees Celsius, and the heating is maintained for 2.5 hours to 3.5 hours; cooling the salt core to a holding temperature and performing holding, wherein the thermal expansion coefficient of the salt core at the holding temperature and the thermal expansion coefficient of the sand core at normal temperature are substantially the same.

6. The casting method according to claim 1, characterized by, The lower sand core comprises a lower matching surface, a lower embedded part and a lower positioning groove which is recessed from the lower matching surface, the upper sand core comprises an upper matching surface, an upper embedded part and an upper positioning groove which is recessed from the upper matching surface, the lower matching surface and the upper matching surface are matched with each other, the lower embedded part and the upper embedded part are at least two bosses and grooves which are complementarily embedded, and the lower positioning groove and the upper positioning groove define the cylinder part.

7. The casting method according to claim 1, characterized by, The injection of the aluminum alloy solution and the cooling to form the casting comprise: The lower mold device is provided with at least one forming groove and pouring channels which are located at two sides of the forming groove, the pouring channels are provided with three intermediate molten pools and injection ports which correspond to each intermediate molten pool and are arranged at intervals along a flowing direction, and the injection ports are arranged in a direction towards the sand core assembly and are arranged in a staggered manner with the cylinder part.

8. The casting method according to claim 7, characterized in that, The injection of the aluminum alloy solution and the cooling to form the casting comprise: controlling the mold temperature to be at 360 degrees Celsius to 400 degrees Celsius by starting a cooling mechanism; controlling the mold to maintain pressure for 350 seconds to 370 seconds.

9. The casting method according to claim 1, characterized by, The heat treatment of the caliper blank includes: solid solution treatment of the caliper blank, heating temperature is 530-550 ℃, holding time is 5-8.5 hours; controlling the solid solution transfer time to be less than or equal to 30 seconds; aging treatment of the caliper blank, aging treatment temperature is 160-175 ℃, holding time is 6-7.5 hours.

10. The casting method according to claim 1, characterized by, The flushing of the salt core in the caliper blank includes: flushing the salt core in the caliper blank by the flushing medium; dissolving the salt core in the caliper blank, and forming corresponding oil passage and cylinder space in the caliper blank.

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