A brake drum, a casting tooling fixture, and a casting method

Abstract

The application discloses a brake drum, comprising: a steel shell layer in a cylindrical configuration, a first end of which is processed into a flange structure, and a transition circular arc is arranged on the inner wall of the steel shell layer close to the first end and faces the central axis of the steel shell layer, and a blocking ring is arranged on the second end of the steel shell layer extending towards the central axis; and a gray cast iron layer which is cast into the inner wall of the steel shell layer, the two ends of the gray cast iron layer in the axial direction respectively contact the transition circular arc and the blocking ring, and the gray cast iron layer and the steel shell layer are metallurgically combined through a fusion layer. The inner surface of the steel shell layer is melted by high-temperature molten iron through the centrifugal casting mode, so that the steel shell layer and the gray cast iron layer are metallurgically combined, thereby improving the bonding strength of the two-layer metal structure and reducing the cracking failure risk of the brake drum. The application also provides a pouring tool clamp and a pouring method of the brake drum.

Description

Technical Field

[0001] This invention relates to the field of brake drum equipment technology, and in particular to a brake drum, a casting fixture and casting method. Background Technology

[0002] Brake drums are components in braking systems used to generate braking force that impedes the movement or tendency of a vehicle. With the development of automotive design technology, vehicles are now designed for numerous high-tonnage, high-speed, and long-duration continuous driving conditions. Traditional pure gray iron brake drums often experience problems such as lateral fracture (bottoming out) or longitudinal cracking (explosion) during use. To address these issues, bimetallic composite brake drums have emerged as a replacement for pure gray iron drums. These composites improve the strength of the brake drum and reduce the risk of fracture by combining two metals. However, bimetallic composites require layered production and the combination of two metals, making the production process difficult to control. This can lead to problems such as severe eccentricity of the brake drum blank, large dynamic imbalance, and loose bonding between the steel and iron in the brake drum. In severe cases, this can directly affect the structural integrity and braking accuracy of the brake drum, posing a risk of brake failure.

[0003] Therefore, how to improve the strength and service life of brake drums and reduce the defect rate of brake drum production is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a brake drum with high strength, long service life and low defect rate.

[0005] Another object of the present invention is to provide a casting fixture for producing the above-mentioned brake drum.

[0006] Another object of the present invention is to provide a casting method for producing brake drums using the above-mentioned casting tooling fixture.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A brake drum, comprising:

[0009] The steel shell is cylindrical in shape. The first end of the steel shell is machined into a flange structure. The inner wall of the steel shell is provided with a transition arc near the first end. The protrusion of the transition arc faces the central axis of the steel shell. The second end of the steel shell extends towards the central axis and is provided with a blocking ring.

[0010] A gray cast iron layer is cast into the inner wall of the steel shell layer. The two ends of the gray cast iron layer in the axial direction respectively contact the transition arc and the blocking ring, and the gray cast iron layer and the steel shell layer are metallurgically bonded by a fusion layer.

[0011] Preferably, in the above-mentioned brake drum, the thickness of the blocking ring is not less than 5mm, and the distance between the inner circumference of the blocking ring and the inner wall of the gray cast iron layer is 3mm-15mm.

[0012] Preferably, in the above-mentioned brake drum, the thickness of the fusion layer does not exceed 1 mm, and the minimum thickness of the gray cast iron layer is not less than 6 mm.

[0013] Preferably, in the above-mentioned brake drum, the fusion layer is formed by mixing the molten steel shell inner wall with liquid gray cast iron and then cooling.

[0014] Preferably, in the above-mentioned brake drum, the steel shell layer is formed in one step by a spinning and rolling process.

[0015] A casting fixture for producing brake drums as described in any of the above embodiments, the casting fixture comprising:

[0016] The flange includes an annular axial positioning plate and a radial positioning plate, the axial positioning plate being parallel to and spaced apart from the radial positioning plate. The axial positioning plate is used to fit against the outer plane of the flange structure, and the radial positioning plate is used to be inserted into the inner circle of the flange structure with a gap.

[0017] An expansion sleeve is disposed within the annulus of the axial positioning disk and the radial positioning disk. A push rod is connected to the inclined side of the expansion sleeve facing the inner circle of the radial positioning disk. The inner side of the expansion sleeve is connected to the piston rod. The piston rod drives the expansion sleeve to move axially and pushes the push rod to move toward the inner circle surface of the radial positioning disk.

[0018] A floating positioning column is disposed between the axial positioning disk and the radial positioning disk. The floating positioning column and the push rod are floatingly connected by a buffer spring. When the push rod moves toward the inner circular surface of the radial positioning disk, it pushes one side of the floating positioning column to extend out of the outer circumference of the radial positioning disk. At least three floating positioning columns are evenly arranged in the circumferential direction of the radial positioning disk.

[0019] Preferably, in the above-mentioned casting fixture, the floating positioning column is T-shaped and fitted with a return spring, and the axial positioning plate and the radial positioning plate have stepped grooves that abut against the other side of the return spring.

[0020] Preferably, in the above-mentioned casting fixture, the end of the floating positioning column facing away from the top rod has an arc shape.

[0021] Preferably, in the above-mentioned casting fixture, both the buffer spring and the return spring are rectangular mold springs. The effective stroke of the buffer spring is 10mm-15mm and the elastic force is 40kg-60kg. The effective stroke of the return spring is 5mm-10mm and the elastic force is 15kg-25kg.

[0022] Preferably, the casting fixture also includes a claw joint that is connected to the piston rod in a driving manner. The claw joint is provided with a plurality of pressure claws that rotate in the circumferential direction. When the piston rod extends, it drives the claw joint to move and causes the pressure claws to engage and press in the circumferential direction.

[0023] Preferably, in the above-mentioned casting fixture, the first end of the pressure claw is rotatably connected to the claw joint via a first rotating pin, the second end of the pressure claw is used to fasten and press the flange structure, and the first end and the second end of the pressure claw are rotatably connected to the fixed frame via a second rotating pin.

[0024] Preferably, in the above-mentioned casting fixture, the mounting hole on the claw joint through which the first rotating pin passes is a rectangular hole or an oblong hole.

[0025] Preferably, in the above-mentioned casting fixture, the outer wall of the radial positioning disk is initially spaced 1mm-1.5mm from the inner circular surface of the flange structure.

[0026] A casting method for producing brake drums using the casting fixture described in any of the above embodiments, the casting method comprising at least the following steps:

[0027] Fixing: The flange structure of the formed steel shell layer is centered and clamped using the casting fixture;

[0028] Preheating: The formed steel shell layer is preheated to 800℃~1000℃, and flux is sprayed on the inner wall of the steel shell layer after heating is completed;

[0029] Casting: Set the speed of the centrifuge to 600r / min-800r / min and pour molten iron into the inner wall of the steel shell layer. The pouring temperature of the molten iron is 1400℃~1550℃ and the melting depth of the inner wall of the steel shell layer is 0.3mm-1mm.

[0030] Molding: Maintain centrifugal rotation and cool to solidify and shape.

[0031] Preferably, in the above casting method, during the casting step, the molten iron is discharged and cast through a plurality of casting holes, and the first casting hole of the molten iron is 50mm-65mm away from the axial upper edge of the gray cast iron layer.

[0032] As can be seen from the above technical solution, the brake drum provided by the present invention includes a steel shell layer, a gray cast iron layer, and a fusion layer. Specifically, the steel shell layer has a cylindrical structure to form the external structure of the brake drum. The first end of the steel shell layer is machined into a flange structure for subsequent production and installation. The inner wall of the steel shell layer has an arc-shaped transition arc near its first end. The protrusion of the transition arc faces the central axis of the steel shell layer, so that the transition arc is closer to the central axis than other areas of the side wall of the steel shell layer. Correspondingly, the second end of the steel shell layer extends towards the central axis and is provided with a blocking ring. The blocking ring and the transition arc are connected. The arc-shaped structure forms a concave area that bears the molten iron. Based on this, the gray cast iron layer is set on the inner wall of the steel shell layer by casting. The two ends of the gray cast iron layer in the axial direction respectively contact the transition arc and the blocking ring. In particular, the gray cast iron layer and the steel shell layer achieve metallurgical bonding through a fusion layer. That is, during the casting process of the gray cast iron layer, the inner wall of the steel shell layer melts and forms a structural layer with atomic diffusion and tight connection with the molten iron. This makes the brake drum present a three-layer structure in the thickness direction of the side wall. Moreover, the metallurgically bonded gray cast iron layer and the steel shell layer have high bonding strength and are not prone to bottoming out or cracking. The brake drum provided by this invention features a transition arc and a blocking ring designed on the inner wall of the steel shell structure to form a recessed structure on the inner wall of the steel shell, providing space for the casting of the gray cast iron layer. At the same time, during casting, the inner wall of the steel shell is melted to form a fusion layer with the molten iron. The fusion layer enables the metallurgical bonding between the gray cast iron layer and the steel shell layer, thereby improving the integrity and structural strength of the brake drum and extending its service life. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 This is a schematic diagram of the cross-sectional structure of the brake drum provided in an embodiment of the present invention;

[0035] Figure 2 This is a schematic cross-sectional view of the casting fixture clamping the steel shell layer according to an embodiment of the present invention.

[0036] Figure 3 for Figure 2 Detailed drawing of the floating positioning column area;

[0037] Figure 4 This is a schematic diagram of the claw-type connector area structure provided in an embodiment of the present invention;

[0038] Wherein, 10-steel shell layer; 110-flange structure; 120-transition arc; 130-blocking ring; 20-gray cast iron layer; 30-fusion layer;

[0039] 410 - Axial positioning disc; 420 - Radial positioning disc; 510 - Expansion sleeve; 520 - Push rod; 530 - Floating positioning pin; 540 - Buffer spring; 550 - Return spring; 60 - Piston rod; 710 - Claw joint; 7110 - Mounting hole; 720 - Pressure claw; 730 - First rotating pin; 740 - Second rotating pin; 750 - Fixing bracket. Detailed Implementation

[0040] The core of this invention is to disclose a brake drum with high strength, long service life and low defect rate.

[0041] Another object of the present invention is to provide a casting fixture for producing the above-mentioned brake drum.

[0042] Another object of the present invention is to provide a casting method for producing brake drums using the above-mentioned casting tooling fixture.

[0043] To enable those skilled in the art to better understand the present invention, embodiments of the present invention will be described below with reference to the accompanying drawings. Furthermore, the embodiments shown below do not limit the scope of the invention as described in the claims. Additionally, the complete contents of the configurations shown in the embodiments below are not limited to those necessary for the solution of the invention described in the claims.

[0044] like Figure 1As shown, the brake drum provided in this embodiment of the invention includes a steel shell layer 10, a gray cast iron layer 20, and a fusion layer 30. Specifically, the steel shell layer 10 has a cylindrical configuration to form the external structure of the brake drum. The first end of the steel shell layer 10 is machined into a flange structure 110 for subsequent manufacturing and installation. The inner wall of the steel shell layer 10 has an arc-shaped transition arc 120 near its first end. The protrusion of the transition arc 120 faces the central axis of the steel shell layer 10, so that the transition arc 120 is closer to the central axis than other areas of the side wall of the steel shell layer 10. Correspondingly, the second end of the steel shell layer 10 also extends towards the central axis and is provided with a blocking ring 130. The blocking ring 130 and the transition arc 120 are connected. Arc 120 forms a recessed area structure to support molten iron. Based on this, the gray cast iron layer 20 is set on the inner wall of the steel shell layer 10 by casting. The two ends of the gray cast iron layer 20 in the axial direction respectively contact the transition arc 120 and the blocking ring 130. In particular, the gray cast iron layer 20 and the steel shell layer 10 are metallurgically bonded through the fusion layer 30. That is, during the casting process of the gray cast iron layer 20, the inner wall of the steel shell layer 10 melts and forms a structural layer with atomic diffusion and tight connection with the molten iron. This makes the brake drum present a three-layer structure in the thickness direction of the side wall. The metallurgically bonded gray cast iron layer 20 and steel shell layer 10 have high bonding strength and are not prone to bottoming out or cracking.

[0045] The brake drum provided in this embodiment of the invention features a transition arc 120 and a retaining ring 130 designed on the inner wall of the steel shell layer 10 structure to form a recessed structure on the inner wall of the steel shell layer 10, providing space for the casting of the gray cast iron layer 20. At the same time, during casting, the inner wall of the steel shell layer 10 is melted to form a fusion layer 30 with the molten iron. The fusion layer 30 can achieve metallurgical bonding between the gray cast iron layer 20 and the steel shell layer 10, thereby improving the integrity and structural strength of the brake drum and extending its service life.

[0046] Furthermore, based on the above embodiments, the thickness of the blocking ring 130 is not less than 5mm, so as to avoid the molten iron from burning through the end of the steel shell layer 10 during the pouring process of the gray cast iron layer 20 if the thickness of the blocking ring 130 is too thin. At the same time, it is preferable that the inner circumference of the blocking ring 130 is 3mm-15mm away from the inner wall of the gray cast iron layer 20. On the one hand, this prevents the risk of molten iron splashing due to the blocking ring 130 being too low, and on the other hand, it avoids the problem of the blocking ring 130 being too high, which would affect the pouring and waste steel plates.

[0047] Furthermore, in order to improve service life while ensuring structural strength, the thickness of the fusion layer 30 is preferably no more than 1 mm, so as to ensure that the minimum thickness of the gray cast iron layer 20 is not less than 6 mm, thereby ensuring that the brake drum has sufficient area to cooperate with the friction pads and thus ensuring its service life and braking effect.

[0048] Furthermore, in the brake drum provided in this embodiment of the invention, the fusion layer 30 is formed by mixing the inner wall of the molten steel shell layer 10 with liquid gray cast iron and then cooling it. Specifically, the partial chemical composition of the steel shell layer 10 is: C (carbon): ≤0.12%, Si (silicon): ≤0.25%, Mn (manganese): ≤1.2%, S (sulfur): ≤0.02%, P (phosphorus): ≤0.03%; while the partial chemical composition of the gray cast iron layer 20 is: C: 3.2-3.7%, Si: 1.5-2.10%, Mn: 0.5-1.1%, S: ≤0.12%, P: ≤0.15%, Cr (chromium): 0.2-0.6%; and the partial chemical composition of the fusion layer 30 is: C ≤3.0%, Si: ≤2.0%, Mn ≤1.2%, S: ≤0.1%, Cr: ≤0.3%.

[0049] It should be further explained that the steel shell layer 10 is mainly composed of ferrite, which gives the steel shell layer 10 strong toughness, while the metallographic structure of the gray cast iron layer 20 has more than 95% pearlite. Pearlite is a mechanical mixture composed of ferrite and cementite, which gives the gray cast iron layer 20 high hardness, tensile strength and wear resistance.

[0050] Furthermore, in the brake drum provided in this embodiment of the invention, the ultimate pull-out strength of the fusion layer 30 in the pull-out test is ≥200MPa, while the tensile strength of the gray cast iron layer 20 is ≥220MPa, and the hardness is 190HBW-240HBW.

[0051] Furthermore, in the brake drum provided in this embodiment of the invention, the steel shell layer 10 is formed in one step by a spinning and rolling process to meet its complex sidewall structure requirements.

[0052] Based on the above embodiments, during the pouring of the gray cast iron layer 20, the steel shell layer 10 needs to be concentrically set with the pouring head to avoid problems such as eccentricity of the brake drum blank, large dynamic balance, non-roundness of the friction surface, and black skin scrap caused by eccentric installation. To ensure the concentricity of the steel shell layer 10 and the pouring head during production, such as... Figure 2 and Figure 3As shown, this embodiment of the invention also provides a casting fixture for producing the brake drum provided in any of the above embodiments. Specifically, the casting fixture includes an axial positioning plate 410, a radial positioning plate 420, a shrink sleeve 510, and a floating positioning column 530. The axial positioning plate 410 and the radial positioning plate 420 are both annular structures, and the axial positioning plate 410 and the radial positioning plate 420 are parallel and spaced apart. The axial positioning plate 410 is used to conform to the outer plane of the flange structure 110 for axial positioning of the steel shell layer 10, while the radial positioning plate 420 is used to be fitted into the inner circle of the flange structure 110 for radial positioning of the steel shell layer 10. It should be noted that the radial positioning plate 420 is only used for pre-positioning of the steel shell layer 10, so it is fitted with the inner circle of the flange structure 110 with a clearance to enable quick assembly. In addition, the radial positioning plate 420 preferably adopts a split three-piece structure to facilitate processing and assembly. Each piece of the structure is connected and fixed to the axial positioning plate 410 by bolts.

[0053] It should be further explained that the axial positioning plate 410 and the radial positioning plate 420 are aligned concentrically with the casting head through other structures, such as mounting bases. The mounting bases serve to provide centering support and rotate synchronously with the casting head, which will not be described in detail here.

[0054] The expansion sleeve 510 is disposed within the annular structure of the axial positioning disk 410 and the radial positioning disk 420. Specifically, the side of the expansion sleeve 510 facing the radial positioning disk 420 is designed as a bevel structure, and a push rod 520 is connected to the bevel structure. It should be noted that the push rod 520 can directly connect to the expansion sleeve 510, or it can be embedded in a dovetail groove opened on the side of the expansion sleeve 510. At the same time, the inner side of the expansion sleeve 510 is connected to the piston rod 60 for transmission, and the piston rod 60 is used to drive the expansion sleeve 510. The piston rod 60 moves axially. When the expansion sleeve 510 moves away from the piston rod 60, it pushes the push rod 520 through the inclined structure, causing the push rod 520 to move towards the inner surface of the radial positioning disk 420. Simultaneously, the floating positioning pin 530 is positioned between the axial positioning disk 410 and the radial positioning disk 420, and the floating positioning pin 530 is floatingly connected to the movable end of the push rod 520 via a buffer spring 540. The push rod 520 moves towards the inner surface of the radial positioning disk 420... During the process, the floating positioning column 530 is driven to move by compressing the buffer spring 540. It should be noted that when the floating positioning column 530 is not pushed by the push rod 520, the end of the floating positioning column 530 away from the push rod 520 is within the outer circumference of the radial positioning disk 420, allowing the radial positioning disk 420 to smoothly engage with the inner circle of the flange structure 110. When the push rod 520 moves to its limit position towards the inner surface of the radial positioning disk 420, the end of the floating positioning column 530 away from the push rod 520 is pushed and extends... When the radial positioning plate 420 is inserted into the inner circle of the flange structure 110, the floating positioning column 530 will press against the flange structure 110 from the inner circle stop position. At the same time, at least three floating positioning columns 530 are evenly arranged in the circumferential direction of the radial positioning plate 420. The simultaneous pressing of the three points can determine a unique geometric circle, thereby ensuring the concentricity of the connection between the flange structure 110 and the radial positioning plate 420, that is, between the flange structure 110 and the casting head.

[0055] It should be noted that the floating positioning pins 530 are evenly arranged in the circumferential direction of the radial positioning disk 420, which specifically means that the included angle between any two adjacent floating positioning pins 530 is equal. More than three floating positioning pins 530 can also be set to improve the centering accuracy.

[0056] It should be further noted that, in one embodiment of the present invention, the axial travel of the expansion is approximately 100 mm, while the radial travel of the push rod 520 on the radial positioning plate 420 is approximately 10 mm.

[0057] Based on the above embodiments, in order to keep the floating positioning post 530 in a state of retraction within the radial positioning disc 420 under normal conditions, and to allow the positioning end of the floating positioning post 530 to retract into the outer circumference within the radial positioning disc 420 after a single positioning is completed and the brake drum is removed, in a preferred embodiment of the present invention, the floating positioning post 530 has a T-shaped structure, and a return spring 550 is sleeved on the floating positioning post 530 in the axial direction. Correspondingly, stepped grooves are opened on the axial positioning disc 410 and the radial positioning disc 420. The two sides of the return spring 550 abut against the stepped groove and the wider end of the floating positioning post 530, respectively. With the help of the return spring 550, the floating positioning post 530 is reset when the piston rod 60 drives the expansion sleeve 510 to move after the brake drum production is completed.

[0058] In order to further improve the positioning effect of the floating positioning column 530 on the flange structure 110, in a specific embodiment of the present invention, the end of the floating positioning column 530 facing away from the top rod 520 is an arc shape, and the radius of the arc of the end of the floating positioning column 530 facing away from the top rod 520 is close to or the same as the radius of the stop of the flange structure 110, so as to increase the contact area between the floating positioning column 530 and the flange structure 110 and improve the tightening effect.

[0059] Furthermore, in the casting fixture provided in this embodiment of the invention, both the buffer spring 540 and the return spring 550 are rectangular mold springs, which have good stability and high temperature resistance. Meanwhile, the effective stroke of the buffer spring 540 is 10mm-15mm, and the elastic force range is 40kg-60kg, which is sufficient to lift the floating positioning column 530 for the steel shell layer 10 with a mass of about 30kg. The effective stroke of the return spring 550 is 5mm-10mm, and the elastic force range is 15kg-25kg, which only needs to be sufficient to pull the floating positioning column 530 back to its original position under the action of the elastic force.

[0060] Furthermore, such as Figure 4 As shown, the casting fixture provided in this embodiment of the invention also includes a claw joint 710 that is connected to the piston rod 60. The claw joint 710 is rotatably provided with a plurality of pressure claws 720 in its circumferential direction. The protruding ends of the plurality of pressure claws 720 in the circumferential direction form a pressing surface for pressing the flange structure 110. When the piston rod 60 extends, it drives the claw joint 710 to move, thereby driving the pressure claws 720 to rotate and clamp in the circumferential direction. When the casting fixture clamps the flange structure 110 on the steel shell layer 10, the pressure claws 720 will clamp from the inside of the flange structure 110 to fix the steel shell layer 10.

[0061] It should be noted that, preferably, three pressure claws 720 are evenly arranged in the circumferential direction of the claw joint 710 to ensure the pressing effect while simplifying the fixture structure.

[0062] To further optimize the above technical solution, in a specific embodiment of the present invention, the first end of the pressure claw 720 is rotatably connected to the claw connector 710 through the first rotating pin 730, while the second end of the pressure claw 720 is used for the action of fastening and pressing. At the same time, the first end and the second end of the pressure claw 720 are rotatably connected to the fixing frame 750 through the second rotating pin 740. When the piston rod 60 pushes the claw connector 710 to move, the first end of the pressure claw 720 is raised, and the pressure claw 720 rotates around the second rotating pin 740 as the rotation center to realize the action of fastening and pressing of the second end of the pressure claw 720.

[0063] Based on the above embodiments, it is preferable that the mounting hole 7110 on the claw connector 710 through which the first rotating pin 730 passes is a rectangular hole or an oblong hole, so that the first rotating pin 730 can move freely in the mounting hole 7110, thereby avoiding the problem of jamming during the rotation of the pressure claw 720.

[0064] Furthermore, in a specific embodiment of the present invention, the outer wall of the radial positioning disk 420 is initially spaced 1mm-1.5mm from the inner circular surface of the flange structure 110, so as to improve the centering accuracy of the pre-positioning while facilitating assembly.

[0065] This invention also provides a casting method for producing brake drums using the casting fixtures provided in any of the above embodiments. Specifically, the casting method includes at least the following steps:

[0066] S01: Fixing: Use casting fixtures to center and clamp the flange structure of the formed steel shell layer;

[0067] S02: Preheating: Preheat the formed steel shell to 800℃~1000℃, and spray flux on the inner wall of the heated steel shell.

[0068] S03: Casting: Set the speed of the centrifuge to 600r / min-800r / min and pour molten iron into the inner wall of the steel shell. The pouring temperature of the molten iron is 1400℃~1550℃, and the melting depth of the inner wall of the steel shell is 0.3mm-1mm.

[0069] S04: Molding: Maintain centrifugal rotation and cool to solidify and form.

[0070] Furthermore, in step S02, the steel shell layer is preheated to reduce the temperature difference between the steel shell layer and the molten iron, so as to facilitate the formation of a fusion layer. The flux is a chloride or fluoride to increase the wettability of the steel shell layer surface.

[0071] Furthermore, in step S03, the centrifuge action can make the casting more compact and cause the slag in the molten iron to float on the surface of the molten iron, which can be removed during machining and reduce the slag inclusion defects in the brake drum.

[0072] Furthermore, in step S03, molten iron is discharged and poured through several pouring holes, and the first pouring hole of molten iron is 50mm-65mm away from the axial upper edge of the gray cast iron layer. The injection of molten iron through the pouring hole can make the molten iron spread inward under the action of centrifugal force, forming the effect of molten iron rolling and stirring in the steel shell layer, so that the inoculant can be fully melted.

[0073] The terms "first," "second," "left side," and "right side," etc., used in the specification, claims, and accompanying drawings of this invention are used to distinguish different objects, not to describe a specific order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units may include steps or units not listed, but rather steps or units not listed.

[0074] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A casting fixture, characterized in that, For use in the production of brake drums, the brake drum comprising: The steel shell layer (10) is cylindrical. The first end of the steel shell layer (10) is processed into a flange structure (110). The inner wall of the steel shell layer (10) is provided with a transition arc (120) near the first end. The protrusion of the transition arc (120) faces the central axis of the steel shell layer (10), and the second end of the steel shell layer (10) extends towards the central axis and is provided with a blocking ring (130). A gray cast iron layer (20) is cast into the inner wall of the steel shell layer (10). The two ends of the gray cast iron layer (20) in the axial direction respectively contact the transition arc (120) and the blocking ring (130), and the gray cast iron layer (20) and the steel shell layer (10) are metallurgically bonded by the fusion layer (30). The casting fixture includes: The axial positioning disk (410) and the radial positioning disk (420) are arranged parallel to each other and spaced apart. The axial positioning disk (410) is used to fit against the outer plane of the flange structure (110), and the radial positioning disk (420) is used to be inserted into the inner circle of the flange structure (110) with a gap. An expansion sleeve (510) is disposed within the annulus of the axial positioning disk (410) and the radial positioning disk (420). The expansion sleeve (510) has a push rod (520) on one side of its inclined surface facing the inner circle of the radial positioning disk (420). The inner side of the expansion sleeve (510) is connected to the piston rod (60) for transmission. The piston rod (60) drives the expansion sleeve (510) to move axially and pushes the push rod (520) to move toward the inner circle surface of the radial positioning disk (420). A floating positioning column (530) is disposed between the axial positioning disk (410) and the radial positioning disk (420). The floating positioning column (530) and the push rod (520) are floatingly connected by a buffer spring (540). When the push rod (520) moves toward the inner circular surface of the radial positioning disk (420), it pushes one side of the floating positioning column (530) to extend out of the outer circumference of the radial positioning disk (420). At least three floating positioning columns (530) are evenly arranged in the circumferential direction of the radial positioning disk (420).

2. The casting fixture as described in claim 1, characterized in that, The thickness of the blocking ring (130) is not less than 5mm, and the distance between the inner circumference of the blocking ring (130) and the inner wall of the gray cast iron layer (20) is 3mm-15mm.

3. The casting fixture as described in claim 1, characterized in that, The thickness of the fusion layer (30) is no more than 1 mm, the minimum thickness of the gray cast iron layer (20) is not less than 6 mm, and the chemical composition of the fusion layer (30) is: C≤3.0%, Si:≤2.0%, Mn≤1.2%, S:≤0.1%, Cr:≤0.3%.

4. The casting fixture as described in claim 1, characterized in that, The fusion layer (30) is formed by mixing the inner wall of the molten steel shell layer (10) with liquid gray cast iron and then cooling it.

5. The casting fixture as described in claim 1, characterized in that, The steel shell layer (10) is formed in one step by a spinning and rolling process.

6. The casting fixture as described in claim 1, characterized in that, The floating positioning column (530) has a T-shaped configuration and is fitted with a return spring (550). The axial positioning plate (410) and the radial positioning plate (420) have stepped grooves that abut against the other side of the return spring (550).

7. The casting fixture as described in claim 6, characterized in that, The end of the floating positioning column (530) facing away from the top rod (520) has an arc shape.

8. The casting fixture as described in claim 6, characterized in that, Both the buffer spring (540) and the return spring (550) are rectangular mold springs. The effective stroke of the buffer spring (540) is 10mm-15mm and the elastic force is 40kg-60kg. The effective stroke of the return spring (550) is 5mm-10mm and the elastic force is 15kg-25kg.

9. The casting fixture as described in claim 1, characterized in that, It also includes a claw joint (710) that is connected to the piston rod (60) for transmission. The claw joint (710) is provided with a plurality of pressure claws (720) for circumferential rotation. When the piston rod (60) extends, it drives the claw joint (710) to move and causes the pressure claws (720) to engage and press in the circumferential direction.

10. The casting fixture as described in claim 9, characterized in that, The first end of the pressure claw (720) is rotatably connected to the claw joint (710) via a first rotating pin (730), and the second end of the pressure claw (720) is used to fasten and press the flange structure (110). The first end and the second end of the pressure claw (720) are rotatably connected to the fixing frame (750) via a second rotating pin (740).

11. The casting fixture as described in claim 10, characterized in that, The mounting hole (7110) on the claw connector (710) through which the first rotating pin (730) passes is a rectangular hole or an oblong hole.

12. The casting fixture as described in claim 1, characterized in that, The outer wall of the radial positioning disc (420) is initially spaced 1 mm to 1.5 mm from the inner circular surface of the flange structure (110).

13. A casting method, characterized in that, The production of brake drums using the casting fixture according to any one of claims 1-12, wherein the casting method includes at least the following steps: Fixing: The flange structure of the formed steel shell layer is centered and clamped using the casting fixture; Preheating: The formed steel shell layer is preheated to 800℃~1000℃, and flux is sprayed on the inner wall of the steel shell layer after heating is completed; Casting: Set the speed of the centrifuge to 600r / min-800r / min and pour molten iron into the inner wall of the steel shell layer. The pouring temperature of the molten iron is 1400℃~1550℃ and the melting depth of the inner wall of the steel shell layer is 0.3mm-1mm. Molding: Maintain centrifugal rotation and cool to solidify and shape.

14. The casting method as described in claim 13, characterized in that, In the casting step, the molten iron is discharged and cast through several casting holes, and the first casting hole of the molten iron is 50mm-65mm away from the axial upper edge of the gray cast iron layer.

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