Brake drum, production device and forming method

Abstract

The invention discloses a brake drum, a production device and a forming method, the brake drum comprises a ductile iron shell, a plurality of convex parts and a plurality of concave parts are arranged on the inner wall of the ductile iron shell in the circumferential direction of the ductile iron shell, and the total volume of the convex parts is the same as the total volume of the concave parts; and the gray cast iron layer is in pouring connection with the inner wall of the ductile iron shell, and at least part of the outer side of the gray cast iron layer is connected to the protruding part and the concave part so that clamping of the gray cast iron layer and the ductile iron shell can be formed. According to the brake drum, on the premise that the overall weight is not increased, the machining cost is controlled, and the overall strength and rigidity of the brake drum are effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of brake drums, and more specifically to a brake drum. In addition, the present invention also relates to a production device and a molding method for manufacturing the brake drum. Background Art

[0002] The brake drum is an important component in the automobile braking system. It is used to produce a braking effect by rubbing against the brake shoe, allowing the car to stop as needed to ensure driving safety and braking performance. How to improve the performance of the brake drum has always been a hot topic in the industry.

[0003] In the high-strength and high-thermal-conductivity new material solid-liquid composite brake drum and its preparation method, the processing form of the brake drum is as follows: the outer side of the brake drum is cast on the production line of coated sand and sand shell filled with iron particles, and then the inner layer of gray cast iron is cast by centrifugal casting. This method specifically relies on improving the composition of the casting liquid to improve the performance of the structure, but increases the higher processing cost.

[0004] In a bimetallic iron-iron composite brake drum and a manufacturing method thereof, the brake drum is processed as follows: after the outer iron shell is manufactured by shell mold or static pressure casting, a composite inner layer of wear-resistant gray cast iron is cast by centrifugal casting. The thickness of the inner layer of wear-resistant gray cast iron is set to improve the strength and rigidity of the brake drum. This method increases the weight of the brake drum.

[0005] In summary, how to improve the strength and stiffness of the brake drum while controlling the cost and not increasing the weight of the brake drum is a problem that needs to be solved urgently by those skilled in the art. Summary of the invention

[0006] In view of this, the purpose of the present invention is to provide a brake drum. By arranging protrusions and recesses on the ductile iron shell, the gray cast iron layer forms a snap-fit ​​structure with the ductile iron shell after casting. Without increasing the weight of the brake drum, the cost can be controlled and the strength and rigidity of the brake drum can be improved.

[0007] Another object of the present invention is to provide a production device and a molding method for manufacturing the above-mentioned brake drum.

[0008] In order to achieve the above object, the present invention provides the following technical solutions:

[0009] A brake drum, comprising:

[0010] A ductile iron shell, wherein the inner wall of the ductile iron shell is provided with a plurality of protrusions and a plurality of recesses along its circumference, and the total volume of the plurality of protrusions is the same as the total volume of the plurality of recesses;

[0011] The gray cast iron layer is connected to the inner wall of the ductile iron shell by casting, and at least part of the outer side of the gray cast iron layer is connected to the protrusion and the recess to form the engagement between the gray cast iron layer and the ductile iron shell.

[0012] Preferably, a plurality of the protrusions are arranged on the circumference of the inner wall of the ductile iron shell, and a recess is arranged between two adjacent protrusions;

[0013] The center lines of the adjacent protrusions and the center lines of the adjacent recesses are located on both sides of the inner wall surface of the ductile iron shell.

[0014] Preferably, the inner wall of the ductile iron shell is provided with at least one protrusion and at least one recess along its axial direction, and the center line of at least one protrusion coincides with the center line of at least one recess;

[0015] The recessed portion is arranged between two adjacent raised portions.

[0016] Preferably, the inner layer of the grey cast iron layer is provided with a 0.5-1 mm reinforcing coating, and the reinforcing coating covers the inner layer of the grey cast iron layer.

[0017] The present invention also provides a production device for manufacturing the brake drum described in any one of the above items, wherein the mold comprises:

[0018] An upper mold, comprising an upper sand box and a punch, wherein the punch is used to extend into the inner cavity of the upper sand box, and a molding space for a first sand mold shell is formed between the outer edge of the punch and the inner cavity of the upper sand box, and the first sand mold shell is bonded to the inner cavity of the upper sand box;

[0019] A lower mold, comprising a lower sand box and a concave mold, wherein the lower sand box is used to extend into the concave mold, a molding space for a second sand mold shell is formed between an inner edge of the concave mold and an outer edge of the lower sand box, and the second sand mold shell is bonded to the outer edge of the lower sand box;

[0020] The outer circumference of the second sand mold shell is provided with a groove for forming the raised portion and a convex rib for forming the recessed portion, and the upper sand box and the lower sand box are connected to form a molding cavity surface of the ductile iron shell;

[0021] A pouring cup connected to the molding cavity surface for injecting molten ductile iron;

[0022] A clamp connected to the ductile iron shell and used to connect the ductile iron shell to a centrifugal casting machine so as to cast and compound the gray cast iron layer into the ductile iron shell through the rotation of the ductile iron shell;

[0023] The pouring ladle nozzle is connected to the inner cavity of the ductile iron shell and is used for pouring molten grey iron.

[0024] Preferably, the clamp is clamped on the outer side of the large end of the ductile iron shell, the clamp is connected to an adjustment shaft for adjusting the axial position of the clamp, and the axial direction of the clamp is arranged parallel to the axial direction of the ductile iron shell;

[0025] The adjusting shaft has a threaded portion for connecting to the centrifugal casting machine. The threaded portion is matched with a nut, which is threadedly connected to the threaded portion and is used to be pressed onto the centrifugal casting machine.

[0026] Preferably, the large opening end of the ductile iron shell is provided with an end cover plate, and the end cover plate is used to prevent the molten iron in the ductile iron shell from spraying out;

[0027] The three groups of clamps are evenly distributed on the outside of the ductile iron shell, and two groups of clamps are provided with placement grooves for the end cover plates, and there is an unlocking distance between the other group of clamps and the ductile iron shell;

[0028] The part of the clamp close to the large opening is connected to a clamping rotor via a rotating shaft, and is used to clamp the end cover plate or move away from the end cover plate;

[0029] The clamping rotor is pressed against the end cover plate as the ductile iron shell rotates to form a clamping lock, or the clamping rotor is turned over as the end cover plate is unlocked from the unlocking distance.

[0030] Preferably, the clamping rotor is an eccentric rotor, a first end of the eccentric rotor is in contact with the clamp, and a second end of the eccentric rotor is in contact with the end face cover plate;

[0031] The rotating shaft is connected to the clamp through a rotor bracket, and the rotating shaft is arranged close to the first end of the eccentric rotor.

[0032] Preferably, the pouring ladle nozzle comprises a vertical portion, an inclined portion and a horizontal portion, the vertical portion is open at the top and connected to the horizontal portion through the inclined portion, and the horizontal portion extends into the inner cavity of the ductile iron shell through the large opening end thereof;

[0033] The inner bottom wall surface of the horizontal portion is provided with a slope surface, and the slope surface gradually becomes gentler in the direction away from the large end;

[0034] The inner bottom wall surface of the horizontal portion is provided with a first iron injection hole, a second iron injection hole, a third iron injection hole, and a fourth iron injection hole at intervals, and the areas of the first iron injection hole, the second iron injection hole, the third iron injection hole, and the fourth iron injection hole decrease and increase.

[0035] The present invention further provides a molding method, which is used for being applied to any of the above-mentioned production devices to process the brake drum, and the molding method comprises:

[0036] Install the pouring cup into the molding cavity surface;

[0037] The molten ductile iron is smelted and spheroidized and then poured into the pouring cup, and the ductile iron shell is cast at a pouring temperature of 1400-1430° C.;

[0038] Spray water on the upper sand box and the lower sand box for 3 to 5 minutes to cool them to room temperature, and open the mold to take out the formed ductile iron shell;

[0039] Connect the fixture to the outer side of the large end of the ductile iron shell and the centrifugal casting machine, and press the end surface pressing plate against the large end surface of the ductile iron shell;

[0040] The pouring ladle nozzle is connected to the inner cavity of the ductile iron shell, and gray iron liquid with the chemical composition of 3.6%-3.75% C, 1.8%-2.2% Si, 0.75%-0.9% Mn, S≤0.12%, P≤0.08%, Cu≤0.4%, 0.25-0.4% Cr, and 0.2%-0.4% Mo is poured into the inner cavity of the ductile iron shell to form the gray cast iron layer.

[0041] The brake drum provided by the present invention comprises a ductile iron shell and a gray cast iron layer connected to the inner wall of the ductile iron shell by casting, wherein the inner wall of the ductile iron shell is provided with a plurality of protrusions and a plurality of recesses along its circumference, and the outer side of the gray cast iron layer is at least partially connected to the protrusions and the recesses. Due to the arrangement of the protrusions and the recesses, when the gray cast iron layer is cast to form, the gray cast iron layer and the inner wall of the ductile iron shell can form a snap-fitting relationship, so as to improve the strength and rigidity of the brake drum and increase the service life of the brake drum.

[0042] The total volume of several protrusions is the same as the total volume of several recessed portions. Recessed portions and protrusions are arranged on the ductile iron shell. The gray cast iron layer can fill the recessed portions or surround the protrusions correspondingly during casting. The weight of the overall brake drum structure is not increased. Therefore, the strength and rigidity of the brake drum can be improved without increasing the weight of the brake drum, thereby ensuring the use effect of the brake drum.

[0043] The beneficial effect of the present invention is that by arranging the protrusions and the depressions on the ductile iron shell, the gray cast iron layer forms a snap-fit ​​structure with the ductile iron shell after casting, thereby improving the strength and rigidity of the brake drum without increasing the weight of the brake drum and the cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0045] Figure 1 A schematic diagram of the structure of the brake drum provided by the present invention;

[0046] Figure 2 for Figure 1 AA section view;

[0047] Figure 3 A schematic diagram of the structure of the upper mold provided by the present invention;

[0048] Figure 4 This is a schematic diagram of the structure of the lower mold provided by the present invention;

[0049] Figure 5 A schematic diagram of a processing mold for a ductile iron shell provided by the present invention;

[0050] Figure 6 A schematic diagram of a clamping die for a ductile iron shell provided by the present invention;

[0051] Figure 7 for Figure 6 A cross-sectional view of

[0052] Figure 8 A schematic diagram of the connection between the clamp and the clamping rotor provided by the present invention;

[0053] Fig. 9 A schematic diagram of the structure of the compression rotor provided by the present invention;

[0054] Fig.10 This is a schematic diagram of a processing mold for the gray cast iron layer provided by the present invention.

[0055] Figure 1-Figure 10 , the reference numerals include:

[0056] 1-brake drum; 2-upper mold; 3-lower mold; 4-pouring cup; 5-pouring cup sand shell; 6-molding cavity surface; 7-top screw; 8-lock buckle; 9-rotating shaft; 10-clamping rotor; 11-ductile iron shell; 12-gray cast iron layer; 13-clamp; 14-nut; 15-centrifugal pouring machine; 16-end cover plate; 17-pouring ladle nozzle; 18-rotor bracket; 19-adjusting shaft; 111-protrusion; 112-recess; 131-placing groove; 171-vertical part; 172-inclined part; 173-horizontal part; 1731-first iron injection hole; 1732-second iron injection hole; 1733-third iron injection hole; 1734-fourth iron injection hole;

[0057] 21-upper sand box; 22-punch; 23-first sand mold shell; 211-sand injection hole; 31-die; 32-lower sand box; 33-second sand mold shell; 331-convex rib; 332-groove; 81-inclined surface. DETAILED DESCRIPTION

[0058] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0059] The core of the present invention is to provide a brake drum, which can control the processing cost without increasing the overall weight and effectively improve the overall strength and rigidity of the brake drum. Another core of the present invention is to provide a mold and a molding method for manufacturing the above brake drum.

[0060] The brake drum provided by the present invention comprises a ductile iron shell 11 and a gray cast iron layer 12. The inner wall of the gray cast iron layer 12 is cast connected to the ductile iron shell 11 to form a brake drum. Figure 1 .

[0061] Please refer to Figure 2 The inner wall of the ductile iron shell 11 is provided with a plurality of protrusions 111 and a plurality of recesses 112 along its circumference, where the circumference refers to one circumference of the inner wall of the ductile iron shell 11. By providing the protrusions 111 and the recesses 112, when the gray cast iron layer 12 is connected to the inner wall of the ductile iron shell 11, a portion embedded in the recesses 112 and a portion clamped with the protrusions 111 can be formed, so that after the gray cast iron is poured into the ductile iron shell 11, the gray cast iron layer 12 and the ductile iron shell 11 are clamped, so as to achieve the effect of improving the overall strength and rigidity of the brake drum and ensure the service life of the brake drum.

[0062] In addition, the gray cast iron layer 12 and the ductile iron shell 11 are engaged with each other, so that the gray cast iron layer 12 and the ductile iron shell 11 can better transmit force, thereby ensuring the reliable use effect of the brake drum.

[0063] There is no limitation on the specific structural forms of the recessed portion 112 and the raised portion 111, such as an arc structure or a square structure, as long as the requirements can be met.

[0064] The total volume of the plurality of recesses 112 is the same as the total volume of the plurality of recesses 112 . When the density of molten iron remains unchanged, the weight of the overall brake drum does not increase after the gray cast iron layer 12 and the ductile iron shell 11 are cast and connected, thereby ensuring the use effect of the brake drum without increasing material costs.

[0065] In a specific embodiment, the number of the protrusions 111 and the number of the recesses 112 are the same. In this case, the volume of each protrusion 111 and each recess 112 is the same to ensure that the total volume of all the protrusions 111 and all the recesses 112 is the same; or the volume of each protrusion 111 and each recess 112 is not the same, as long as the total volume of all the protrusions 111 and the total volume of all the recesses 112 are the same.

[0066] In another specific embodiment, the number of protrusions 111 and recesses 112 are inconsistent, and the volume of each protrusion 111 and each recess 112 are inconsistent, and the total volume of all protrusions 111 and the total volume of all recesses 112 are ensured to be the same.

[0067] At least part of the outer side of the gray cast iron layer 12 is cast and connected to the protrusion 111 and the recess 112. At least part of the outer side of the gray cast iron layer 12 may be only partly cast and connected to the protrusion 111 and the recess 112, and the remaining part is connected to the inner wall. Figure 2 or the entire outer side is used to connect with the raised portion 111 and the recessed portion 112, in which case the recessed portion 112 and the raised portion 111 are connected to form a wavy structure.

[0068] On the basis of the above-mentioned embodiment, a plurality of protrusions 111 are arranged on the inner wall of the ductile iron shell 11 in the circumferential direction, and a recessed portion 112 is arranged between two adjacent protrusions 111. Figure 2 As shown, the protrusions 111 and the recesses 112 are arranged at intervals on the inner wall of the ductile iron shell 11, and the corresponding gray cast iron layer 12 will also form recesses and protrusions arranged at intervals on its surface after casting, so that the gray cast iron layer 12 and the ductile iron shell 11 form a snap-fitting relationship after casting and connection, so as to form a cam structure, so as to achieve the effect of improving the overall strength and rigidity of the brake drum and ensure the service life of the brake drum.

[0069] In this case, the protrusions 111 and the recesses 112 can be set to an arc structure, and the total volume of several protrusions 111 and the total volume of several recesses 112 are equal, so as to improve the strength and rigidity of the brake drum without increasing the weight of the brake drum and increase its service life.

[0070] The center lines of the adjacent protrusions 111 and the center lines of the concave portions 112 are located on both sides of the inner wall surface of the ductile iron shell 11. Figure 2 As shown, the protrusions 111 and the recesses 112 are arranged at intervals along the circumferential direction of the inner wall of the ductile iron shell 11, so that the gray cast iron layer 12 and the ductile iron shell 11 are cast and connected to form a convex structure, thereby improving the strength and rigidity of the brake drum.

[0071] On the basis of any of the above embodiments, the inner wall of the ductile iron shell 11 is provided with at least one protrusion 111 and at least one recess 112 along its axial direction, and the center line of at least one protrusion 111 coincides with the center line of at least one recess 112. In this case, at least one protrusion 111 and at least one recess 112 are provided in the axial direction of a certain section of the inner wall of the ductile iron shell 11, and the protrusions 111 and the recesses 112 are connected or arranged at intervals, and the outer side of the gray cast iron layer 12 is also formed with protrusions and recesses arranged at intervals or connected, so that the gray cast iron layer 12 and the ductile iron shell 11 are engaged after being cast and connected, so as to improve the strength and rigidity of the brake drum. The connection in the above process refers to forming a wavy structure of the protrusions 111 and the recesses 112, so that the outer periphery of the gray cast iron layer 12 is connected to the recesses 112 and the protrusions 111.

[0072] The center line of at least one protrusion 111 coincides with the center line of at least one recess 112, that is, one, two or three protrusions 111 may be provided in the axial direction of a certain section of the inner wall of the ductile iron shell 11, and one, two or three recesses 112 may be provided correspondingly, and the center lines of these protrusions 111 and recesses 112 coincide.

[0073] A recessed portion 112 is disposed between two adjacent protrusions 111 . The adjacent protrusions 111 herein may refer to adjacent protrusions 111 disposed axially in a certain section of the inner wall of the ductile iron shell 11 , or may refer to adjacent protrusions 111 disposed in two certain sections of the inner wall of the ductile iron shell 11 .

[0074] The arrangement of the protrusions 111 and the recesses 112 can be flexibly set according to actual conditions to ensure that the total volume of all the protrusions 111 and all the recesses 112 is equal, so as to improve the rigidity and strength of the brake drum without increasing the weight.

[0075] On the basis of any of the above embodiments, the inner layer of the gray cast iron layer 12 is provided with a reinforcing coating of 0.5~1 mm, and the reinforcing coating covers the inner layer of the gray cast iron layer 12. After the gray cast iron layer 12 is cast, a coating is added to the inner surface of the gray cast iron layer 12 by laser cladding technology to further improve the strength and hardness of the brake drum, which can effectively prevent the generation of cracks, prevent the cracks from spreading, and improve the service life of the brake drum.

[0076] It should be noted that after the gray cast iron layer 12 is poured to form a blank, the surface of the blank is first processed by mechanical processing to grind the blank smooth. This process reserves space for strengthening the coating.

[0077] If the inner diameter of the blank is D1, and the actual inner diameter requirement of the finished gray cast iron layer 12 is D2, the inner diameter of the blank will be changed to D3 after mechanical processing, D3>D2>D1, and the difference between D3 and D2 is the space reserved for the reinforcing coating. By reserving space for the reinforcing coating, the weight of the entire brake drum will not be affected when adding the reinforcing coating, and the strength of the brake drum can be improved without increasing the weight, thereby increasing the service life of the brake drum.

[0078] Taking a specific implementation as an example, if the inner diameter requirement for the finished gray cast iron layer 12 is D2=410mm, the blank formed by casting is D1=404mm, leaving a machining allowance of 3mm. After machining, the inner diameter of the blank becomes D3=412mm. At this time, space for the strengthening coating has been left. A 1mm strengthening coating is added to the blank after machining through laser cladding technology. The inner diameter of the blank after coating becomes 410mm, which meets the inner diameter machining requirement of the finished gray cast iron layer 12.

[0079] On the basis of any of the above embodiments, the present invention further provides a mold for manufacturing the brake drum 1 of the above embodiments, and the mold includes an upper mold 2 and a lower mold 3 .

[0080] Among them, Figure 3 As shown, the upper mold 2 includes an upper sand box 21 and a punch 22. The punch 22 is used to extend into the inner cavity of the upper sand box 21. A casting space for a first sand mold shell 23 is formed between the outer edge of the punch 22 and the inner cavity of the upper sand box 21. The first sand mold shell 23 is bonded to the inner cavity of the upper sand box 21.

[0081] The inner cavity of the upper sand box 21 is provided with a spiral groove with a groove depth of no more than 0.5 mm to increase the bonding force between the inner cavity of the upper sand box 21 and the first sand mold shell 23, to ensure that the first sand mold shell 23 formed in the inner cavity of the upper sand box 21 will not fall off during the mold opening process, and to ensure reliable bonding between the first sand mold shell 23 and the inner cavity of the upper sand box 21.

[0082] The specific molding process of the first sand mold shell 23 is as follows:

[0083] The outer edge of the punch 22 is polished and smoothed to make the surface roughness of the punch 22 not greater than Ra6.3;

[0084] Before sandblasting, a release agent is sprayed on the punch 22 to prevent sticking.

[0085] The upper mold 2 is heated to 180-220 degrees Celsius, and sand is injected into the space between the inner cavity of the upper sand box 21 and the punch 22 through the sand injection hole 211 of the upper sand box 21 with the sand injection time of 3-5 seconds and the sand injection pressure of 0.4-0.6Mpa;

[0086] After a period of heat preservation, the coated sand injected through the sand injection hole 211 tightly combines the sand and gravel into one through the resin inside, and has a certain hardness and strength. Then, the mold is opened, the punch 22 is removed, and the first sand mold shell 23 is left in the inner cavity of the upper sand box 21. This iron mold sand coating method can form a first sand mold shell 23 with a thickness of 6-8mm. By reducing the thickness of the first sand mold shell 23, the coated sand consumed in manufacturing the ductile iron shell 11 is reduced, and the material cost can be greatly reduced compared to shell casting.

[0087] like Figure 4 As shown, the lower mold 3 includes a lower sand box 32 and a die 31 . The lower sand box 32 is used to extend into the die 31 . A casting space for a second sand mold shell 33 is formed between the inner edge of the die 31 and the outer edge of the lower sand box 32 . The second sand mold shell 33 is bonded to the outer edge of the lower sand box 32 .

[0088] A spiral groove with a depth of no more than 0.5 mm is provided on the outer edge of the lower sand box 32 to increase the bonding force between the lower sand box 32 and the second sand mold shell 33 formed by its outer edge, to ensure that the second sand mold shell 33 will not fall off during the mold opening process, and to ensure reliable bonding between the second sand mold shell 33 and the outer edge of the lower sand box 32.

[0089] The specific molding process of the second sand mold shell 33 is as follows:

[0090] The inner edge of the die 31 is polished and smoothed to make the surface roughness of the inner edge of the die 31 not greater than Ra6.3;

[0091] Before sandblasting, spray a mold release agent on the concave mold 31 to prevent mold sticking;

[0092] The lower mold 3 is heated to 180-220 degrees Celsius, and sand is injected into the space formed by the inner side of the concave mold 31 and the outer side of the lower sand box 32 with the operating parameters of sand injection time 3-5 seconds and sand injection pressure 0.4-0.6Mpa;

[0093] After the sand injection is completed, the temperature is kept for a period of time so that the injected coated sand can tightly combine the sand and gravel into one through the resin inside, and have a certain hardness and strength. Then the mold is opened, the concave mold 31 is removed, and the second sand mold shell 33 is left on the outer edge of the lower sand box 32. This iron mold sand coating method can form a second sand mold shell 33 with a thickness of 6-8mm. By reducing the thickness of the second sand mold shell 33, the coating sand consumed in manufacturing the ductile iron shell 11 is reduced, which can greatly reduce the material cost compared to shell casting.

[0094] In the above process, during the pouring of the first sand mold shell 23 and the second sand mold shell 33, there is no need to cyclically add steel shots, which increases the cooling speed, avoids quality problems such as looseness and slag inclusion in the subsequent processed castings, and ensures the subsequent processing and molding quality of the brake drum.

[0095] Please refer to Figure 5After the first sand mold shell 23 and the second sand mold shell 33 are formed, the lower sand box 32 and the upper sand box 21 are connected to form the molding cavity surface 6 of the ductile iron shell 11, and the lower sand box 32 and the upper sand box 21 are connected and fastened by the lock buckle 8 and the top screw 7. Specifically, the lock buckle 8 is sleeved on the surface of the upper sand box 21 and the lower sand box 32, and the top screw 7 passes through the lock buckle 8 to press the upper sand box 21 and the lower sand box 32 to realize the process of mold closing. In this process, an inclined surface 81 can be set on the lock buckle 8 so that the lock buckle 8 can close the surface of the upper sand box 21 and the lower sand box 32 to facilitate mold closing.

[0096] Afterwards, the pouring cup 4 is installed on the upper sand box 21 (the pouring cup sand shell 5 has been formed in the pouring cup 4), and a sealant is set at the joint of the pouring cup 4 and the upper sand box 21 to prevent leakage. Then, molten iron is poured into the molding cavity surface 6 through the pouring cup 4 to obtain the ductile iron shell 11. After molding, the lock buckle 8 and the top screw 7 are released, and the ductile iron shell 11 can be demolded from the molding cavity surface 6 to complete the molding process of the ductile iron shell 11.

[0097] The second sand mold shell 33 of the lower mold 3 is provided with a groove 332 and a convex rib 331. Figure 4 As shown, the grooves 332 and the ribs 331 are arranged to correspond to the raised portions 111 and the recessed portions 112 on the inner wall of the ductile iron shell 11 , so that the inner wall of the ductile iron shell 11 after processing has raised and recessed features, so as to facilitate the formation of the gray cast iron layer 12 .

[0098] After processing the ductile iron shell 11, the ductile iron shell 11 and the centrifugal casting machine 15 are connected by the clamp 13, the rotation of the ductile iron shell 11 is realized by the centrifugal casting machine 15, and gray iron liquid is poured into the inner cavity of the ductile iron shell 11 through a casting ladle pouring nozzle connected to the inner cavity of the ductile iron shell 11. Combined with the rotation of the ductile iron shell 11, the gray cast iron layer 12 will be compounded on the inner wall of the ductile iron shell 11 to complete the casting of the gray cast iron layer 12.

[0099] Based on the above embodiments, please refer to Figure 6 , Figure 7 The clamp 13 is clamped on the outer side of the large end of the ductile iron shell 11 to ensure reliable clamping of the ductile iron shell 11, ensure reliable stability during casting, avoid the production of scrapped products with black skin, ensure the finished product effect of the gray cast iron layer 12, so as to further ensure the finished product rate of the brake drum.

[0100] In addition, the fixture 13 is clamped on the outside of the large end of the ductile iron shell 11 to ensure the reliability of the rotation of the ductile iron shell 11, avoid the situation where the diameter of the large end outer edge expands after casting and the size is difficult to control, and ensure the effect of drum forming.

[0101] The clamp 13 is connected to the adjusting shaft 19, and the adjusting shaft 19 is used to adjust the axial position of the clamp 13. The axial direction of the clamp 13 is set parallel to the axial direction of the ductile iron shell 11. The clamp 13 can be adjusted by the adjusting shaft 19 to be clamped on the outside of the large end of the ductile iron shell 11. Specifically, the outside refers to the position of the reinforcement belt of the ductile iron shell 11, which can realize the positioning and clamping of the ductile iron shell 11 for different brake drums. Specifically, for different brake drums, the distance from the reinforcement belt of the ductile iron shell 11 to the flange is different (the distance here is the axial distance). By adjusting the axial position of the clamp 13, it is ensured that a set of clamps 13 can clamp the large end of the ductile iron shell 11 of different brake drums without replacing the clamp 13, thereby ensuring the production efficiency of the brake drum.

[0102] It should be noted that the clamp 13, whether it is a pneumatic clamp or a hydraulic clamp, has a certain operating stroke. The large end diameter of the ductile iron shell 11 can be reliably clamped within this operating stroke, that is, the radial position of the clamp 13 can be adjusted. Combined with the setting of the adjustment shaft, the processing requirements of ductile iron shells 11 of different heights (axial) and different diameters (radial) can be met. There is no need to replace the clamp 13. The position of the clamp 13 can be flexibly adjusted according to the specific size of the ductile iron shell 11, thereby improving the production efficiency of the brake drum.

[0103] The adjusting shaft 19 has a threaded portion for connecting to the centrifugal casting machine 15, and the threaded portion is matched with a nut 14, which is threadedly connected to the threaded portion and used to be pressed on the centrifugal casting machine 15. Specifically, the axial position of the clamp 13 is changed by the depth of the threaded portion extending into the centrifugal casting machine 15, so as to be suitable for the compression of the large end of the ductile iron shell 11 of different brake drums. After adjusting the insertion depth of the threaded portion, the nut 14 is connected to the part where the threaded portion extends out of the centrifugal casting machine 15, and the nut 14 is pressed on the centrifugal casting machine 15 to limit the movement of the threaded portion, so as to ensure that the clamp 13 reliably clamps the ductile iron shell 11.

[0104] Based on any of the above embodiments, please refer to Figure 6 , Figure 7 An end cover plate 16 is provided at the large mouth end of the ductile iron shell 11. The end cover plate 16 is used to prevent the molten iron in the ductile iron shell 11 from spraying out. The molten iron here is the gray iron molten iron used to cast the gray cast iron layer 12. Through the setting of the end cover plate 16, the molten iron is restricted in the inner cavity of the ductile iron shell 11. Through the rotation of the ductile iron shell 11, the gray cast iron layer 12 is formed on the inner wall of the ductile iron shell 11.

[0105] The three sets of clamps 13 are evenly distributed on the outer side of the ductile iron shell 11, and two sets of clamps 13 are provided with placement grooves 131 for the end cover plates 16. Figure 8The slot 131 at the top of the fixture 13 has a width greater than the thickness of the end cover plate 16, so that the end cover plate 16 can be placed in the slot 131 to form an initial positioning; further, the portion of the fixture 13 close to the large end is connected to a clamping rotor 10 via a rotating shaft 9. When the ductile iron shell 11 rotates, the clamping rotor 10 can rotate in the positive direction relative to the rotating shaft 9 to be pressed against the end cover plate 16 to form a secondary positioning to prevent molten iron from spraying out.

[0106] There is an unlocking distance between the other set of clamps 13 and the ductile iron shell 11, so that the end cover plate 16 can be removed from the large end of the ductile iron shell 11 to facilitate the mold removal. The unlocking distance here is as follows: Figure 6 As shown, the placement groove 131 of the topmost clamp 13 does not contact the end cover plate 16; in addition, this unlocking distance can also facilitate the end cover plate 16 to be unlocked from the large end of the ductile iron shell 11. Specifically, when unlocking is required, the end cover plate 16 is clamped by a manipulator and lifted up to a height of H to move out of the placement groove 131, and the end cover plate 16 and the clamping rotor 10 are in contact and clamped, so the clamping rotor 10 can be rotated in the opposite direction with the movement of the end cover plate 16 to remove the clamping rotor 10 and release the limit on the end cover plate 16, so as to further move the clamping rotor 10 to the right to remove the end cover plate 16. The right and top positions in the above process are based on Figure 6 In terms of the orientation, in a specific application, the end cover plate 16 is clamped by a manipulator, so the movement route of the manipulator is relative to Figure 6 It is certain to ensure that each movement of the manipulator can accurately reach the clamping position corresponding to the end cover plate 16, ensure the stability and reliability of the clamping, and ensure that the movement of the manipulator will not interfere with other components.

[0107] Based on any of the above embodiments, please refer to Figure 8 , Fig. 9 The compression rotor 10 is an eccentric rotor, the center of mass of the eccentric rotor is point B, the first end of the eccentric rotor contacts the fixture 13, and the second end of the eccentric rotor contacts the end face cover plate 16; the first end of the eccentric rotor is specifically connected to the fixture 13 through the rotor bracket 18, the rotating shaft 9 is connected to the rotor bracket 18, and the eccentric rotor is connected to the rotating shaft 9 to form a rotation connection. The rotating shaft 9 is arranged near the first end of the eccentric rotor. When the centrifugal casting machine 15 drives the ductile iron shell 11 to rotate, the eccentric rotor can rotate forward around the rotating shaft 9 under the action of centrifugal force and eccentricity to compress the end face cover plate 16.

[0108] Based on any of the above embodiments, please refer to Fig.10The pouring ladle nozzle 17 includes a vertical portion 171, an inclined portion 172 and a horizontal portion 173. The vertical portion 171 is open at the top and is connected to the horizontal portion 173 through the inclined portion 172. The horizontal portion 173 extends into the inner cavity of the ductile iron shell 11 through the large mouth end of the ductile iron shell 11 to deliver molten gray iron into the inner cavity of the ductile iron shell 11. The gray cast iron layer 12 is cast and formed on the inner wall of the ductile iron shell 11 through the rotation of the ductile iron shell 11 to complete the casting of the brake drum.

[0109] The inclined portion 172 can have a guiding effect to allow the molten iron to flow through the vertical portion 171 to the horizontal portion 173 , and further to be delivered to the inner cavity of the ductile iron shell 11 through the iron outlet on the horizontal portion 173 .

[0110] Furthermore, the inner bottom wall surface of the horizontal portion 173 is provided with a slope surface, and the slope surface gradually becomes gentler in the direction away from the large end, so as to further improve the diversion effect and ensure the flow effect of the molten iron.

[0111] The inner bottom wall of the horizontal portion 173 is sequentially arranged with a first iron injection hole 1731, a second iron injection hole 1732, a third iron injection hole 1733, and a fourth iron injection hole 1734, wherein the first iron injection hole 1731 is arranged closest to the inclined portion 172. The areas of the first iron injection hole 1731, the second iron injection hole 1732, the third iron injection hole 1733, and the fourth iron injection hole 1734 decrease and increase, or in other words, the openings of the first iron injection hole 1731, the second iron injection hole 1732, the third iron injection hole 1733, and the fourth iron injection hole 1734 gradually become larger. Through this arrangement, the flow of molten iron flowing through the four iron injection holes tends to be consistent, so that the flow of molten iron in the horizontal portion 173 is uniform and flows out through the four iron injection holes, thereby ensuring the uniform flow of molten iron and further ensuring the casting effect of the gray cast iron layer 12.

[0112] Taking a specific implementation as an example, if the area of ​​the fourth iron injection hole 1734 is S4, the area of ​​the third iron injection hole 1733 is S3, the area of ​​the second iron injection hole 1732 is S4, and the area of ​​the first iron injection hole 1731 is S1, then S4:S3:S2:S1=(1.7-2.2):(1.5-1.8)(1.2-1.5):1.

[0113] Based on any of the above embodiments, the present invention also provides a molding method of the above mold, please refer to Figure 5 , Figure 7 , Fig. 9 , the molding methods include:

[0114] Install the pouring cup 4 into the molding cavity surface 6;

[0115] The molten iron is smelted and spheroidized and then poured into the pouring cup 4, and the ductile iron shell 11 is cast at a pouring temperature of 1400-1430°C;

[0116] The upper sand box 21 and the lower sand box 32 are sprayed with water for 3 to 5 minutes to reduce the sand box temperature to room temperature, and then the mold is opened to take out the blank structure of the formed ductile iron shell 11;

[0117] Connect the two ends of the clamp 13 to the large end of the formed ductile iron shell 11 and the centrifugal casting machine 15, and press the end surface pressure plate to the large end surface of the ductile iron shell 11;

[0118] Connect the pouring ladle nozzle and the inner cavity of the ductile iron shell 11, pour gray iron water to form a gray cast iron layer 12, the chemical composition of the gray iron water here is: 3.6%-3.75% C, 1.8%-2.2% Si, 0.75%-0.9% Mn, S≤0.12%, P≤0.08%, Cu≤0.4%, 0.25-0.4% Cr, 0.2%-0.4% Mo. By adding molybdenum, the thermal fatigue strength is improved to ensure the service life and performance of the brake drum at high temperature. The high carbon metallographic phase is formed by setting 3.6%-3.75% C, the wear resistance of the brake drum is improved, and the mechanical properties of the brake drum are optimized.

[0119] After the chemical composition of the above-mentioned specific gray iron water is processed and applied in practice, the brake drum formed has a tensile strength of not less than 250Mpa, a hardness of not less than 200HBW, a pearlite content of ≥90%; and phosphorus eutectic + carbide <5%.

[0120] When the ductile iron shell 11 is heated by the high-frequency induction heater, a two-stage heating method is adopted. Specifically, the wall thickness of the L1 segment reinforcement belt is thicker. The head is first inserted into the heater and heated for 15 seconds. Then, the L2 segment is heated for the second time as a whole. Fig.10 Through this secondary heating method, the temperature of the front and rear sections of the ductile iron shell 11 is uniform, so as to ensure the metallographic stability of the subsequent gray iron casting, form less carbides, reduce the defects of the gray iron casting layer, ensure the molding effect of the gray iron casting layer, and ensure the mechanical properties and service life of the brake drum.

[0121] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0122] The above is a detailed introduction to a brake drum, a production device and a molding method provided by the present invention. This article uses specific examples to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method and core ideas of the present invention. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present invention, the present invention can also be improved and modified in a number of ways, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A brake drum, characterized in that: include: A ductile iron shell (11), wherein the inner wall of the ductile iron shell (11) is provided with a plurality of protrusions (111) and a plurality of recesses (112) along its circumference, and the total volume of the plurality of protrusions (111) is the same as the total volume of the plurality of recesses (112); The grey cast iron layer (12) is connected to the inner wall of the ductile iron shell (11) by casting, and at least a part of the outer side of the grey cast iron layer (12) is connected to the raised portion (111) and the recessed portion (112) to form a snap fit between the grey cast iron layer (12) and the ductile iron shell (11).

2. The brake drum according to claim 1, characterized in that: A plurality of protrusions (111) are arranged in the circumferential direction of the inner wall of the ductile iron shell (11), and a recess (112) is arranged between two adjacent protrusions (111); The midlines of the adjacent protrusions (111) and the midlines of the adjacent recesses (112) are located on both sides of the inner wall surface of the ductile iron shell (11).

3. The brake drum according to claim 1, characterized in that: The inner wall of the ductile iron shell (11) is provided with at least one protrusion (111) and at least one recess (112) along the axial direction thereof, and the center line of at least one protrusion (111) and the center line of at least one recess (112) coincide with each other; The recessed portion (112) is provided between two adjacent raised portions (111).

4. The brake drum according to claim 1, characterized in that: The inner layer of the grey cast iron layer (12) is provided with a 0.5-1 mm reinforcement coating, and the reinforcement coating covers the inner layer of the grey cast iron layer (12).

5. A production device, characterized in that: Used for manufacturing the brake drum (1) according to any one of claims 1 to 4, the mold comprising: An upper mold (2) comprises an upper sand box (21) and a punch (22), wherein the punch (22) is used to extend into the inner cavity of the upper sand box (21), and a molding space for a first sand mold shell (23) is formed between the outer edge of the punch (22) and the inner cavity of the upper sand box (21), and the first sand mold shell (23) is bonded to the inner cavity of the upper sand box (21); A lower mold (3) comprises a lower sand box (32) and a concave mold (31), wherein the lower sand box (32) is used to extend into the concave mold (31), and a molding space for a second sand mold shell (33) is formed between an inner edge of the concave mold (31) and an outer edge of the lower sand box (32), and the second sand mold shell (33) is bonded to the outer edge of the lower sand box (32); A groove (332) for forming the raised portion (111) and a convex rib (331) for forming the recessed portion (112) are provided on the outer periphery of the second sand mold shell (33); the upper sand box (21) and the lower sand box (32) are connected to form a molding cavity surface (6) of the ductile iron shell (11); A pouring cup (4) connected to the molding cavity surface (6) for injecting molten ductile iron; A clamp (13) is clamped on the outside of the ductile iron shell (11) and is used to connect the ductile iron shell (11) and the centrifugal casting machine (15) so as to cast and compound the gray cast iron layer (12) into the ductile iron shell (11) by rotating the ductile iron shell (11); A pouring ladle nozzle (17) is connected to the inner cavity of the ductile iron shell (11) and is used for pouring molten grey iron.

6. The production device according to claim 5, characterized in that: The clamp (13) is clamped on the outer side of the large opening end of the ductile iron shell (11), the clamp (13) is connected to an adjustment shaft (19) for adjusting the axial position of the clamp (13), and the axial direction of the clamp is arranged parallel to the axial direction of the ductile iron shell (11); The adjusting shaft (19) has a threaded portion for connecting to the centrifugal casting machine (15), the threaded portion being matched with a nut (14), the nut (14) being threadedly connected to the threaded portion and being used to be pressed onto the centrifugal casting machine (15).

7. The production device according to claim 6, characterized in that: An end cover plate (16) is provided at the large opening end of the ductile iron shell (11), and the end cover plate (16) is used to prevent molten iron in the ductile iron shell (11) from spraying out; The three groups of clamps (13) are evenly distributed on the outside of the ductile iron shell (11), and two groups of clamps (13) are provided with placement grooves (131) for the end surface cover plate (16), and an unlocking distance is provided between the other group of clamps (13) and the ductile iron shell (11); The portion of the clamp (13) close to the large opening is connected to a clamping rotor (10) via a rotating shaft (9) and is used to clamp the end cover plate (16) or move away from the end cover plate (16); The clamping rotor (10) is pressed against the end cover plate (16) as the ductile iron shell (11) rotates to form a clamping lock, or the clamping rotor (10) is turned over as the end cover plate (16) is unlocked from the unlocking distance.

8. The production device according to claim 7, characterized in that: The clamping rotor (10) is an eccentric rotor, a first end of the eccentric rotor is in contact with the clamp, and a second end of the eccentric rotor is in contact with the end surface cover plate (16); The rotating shaft (9) is connected to the clamp (13) via a rotor bracket (18), and the rotating shaft (9) is arranged close to the first end of the eccentric rotor.

9. The production device according to claim 8, characterized in that: The pouring ladle nozzle (17) comprises a vertical portion (171), an inclined portion (172) and a horizontal portion (173); the vertical portion (171) is open at the top and is connected to the horizontal portion (173) via the inclined portion (172); the horizontal portion (173) extends into the inner cavity of the ductile iron shell (11) through the large opening end thereof; The inner bottom wall surface of the horizontal portion (173) is provided with a slope surface, and the slope surface gradually becomes gentler in a direction away from the large end; The inner bottom wall of the horizontal portion (173) is provided with a first iron injection hole (1731), a second iron injection hole (1732), a third iron injection hole (1733), and a fourth iron injection hole (1734) at intervals, and the areas of the first iron injection hole (1731), the second iron injection hole (1732), the third iron injection hole (1733), and the fourth iron injection hole (1734) decrease and increase.

10. A molding method, characterized in that: Used for being applied to the production device according to any one of claims 5 to 9 to process the brake drum (1), the molding method comprising: Installing the pouring cup (4) into the molding cavity surface (6); The molten ductile iron is smelted and spheroidized and then poured into the pouring cup (4), and the ductile iron shell (11) is cast at a pouring temperature of 1400-1430° C.; Spraying water on the upper sand box (21) and the lower sand box (32) for 3 to 5 minutes to cool them to room temperature, and opening the mold to take out the formed ductile iron shell (11); The clamp (13) is connected to the outer side of the large end of the ductile iron shell (11) and the centrifugal casting machine (15), and the end surface pressing plate is pressed against the large end surface of the ductile iron shell (11); The pouring ladle nozzle (17) is connected to the inner cavity of the ductile iron shell (11), and gray iron liquid with a chemical composition of 3.6%-3.75% C, 1.8%-2.2% Si, 0.75%-0.9% Mn, S≤0.12%, P≤0.08%, Cu≤0.4%, 0.25-0.4% Cr, and 0.2%-0.4% Mo is poured into the inner cavity of the ductile iron shell (11) to form the gray cast iron layer (12).

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