Rear band-type brake structure of large die casting machine

Abstract

The utility model discloses a rear band-type brake structure of a large die-casting machine, which belongs to the technical field of die-casting machines and comprises two brake pads which are arranged oppositely, the brake pads correspond to opening and closing oil cylinders one by one, and the opening and closing oil cylinders can drive the two brake pads to be close to each other or far away from each other during operation. Arc-shaped open grooves are formed in the opposite ends of the two brake pads, and when the two brake pads abut against each other, the two arc-shaped open grooves are matched to form a through hole structure; first teeth are arranged on the inner wall of the arc-shaped open groove. The first teeth are provided with rectangular cross sections, and chamfers or fillets are arranged at the tooth roots of the first teeth. A piston rod is arranged at the output end of the opening-closing oil cylinder; one end of the piston rod far away from the opening-closing oil cylinder is connected with the brake pad; a connecting block is arranged at one end, far away from the closing oil cylinder, of the piston rod and is connected with the outer side wall of the brake pad. The band-type brake is simple in structure, accurate in operation, more stable and smooth in operation in the band-type brake process, low in abrasion degree of parts, long in service life and higher in working efficiency.

Description

Technical Field

[0001] The utility model belongs to the technical field of die-casting machines, and in particular relates to a rear brake structure of a large die-casting machine. Background Art

[0002] With the development of automobile integrated molding technology, the design of super-large die-casting machines is also constantly improving. The corresponding automobile castings brought about by automobile integration tend to be larger, and the requirements for casting quality are gradually increasing. This requires super-large die-casting machines with greater clamping force to achieve. The locking components have a great influence on the operating stability of super-large die-casting machines during the clamping process. The traditional rear brake structure mainly relies on a single brake opening and closing cylinder plus a connecting rod to drive the brake pad to move the brake tightening lever. The brake tightening process will cause the running speed of the two brake pads to be different, the running stability is low, and the probability of brake failure is high.

[0003] The utility model patent with announcement number CN202894275U discloses a brake structure of a direct pressure die-casting machine, which includes two brake pads arranged opposite to each other around the outside of the large column of the die-casting machine and a cylinder driving the two brake pads to move. The inner sides of the two brake pads in contact with the large column are provided with brake teeth, and the outer circumference of the large column is provided with column teeth meshing with the brake teeth; the cross section of the gate teeth along the axial direction of the large column is rectangular; the cross section of the column teeth along the axial direction of the large column is rectangular. This structure reduces or even completely avoids the brake from bearing radial force, so the brake is not easy to be damaged and has a longer service life; the brake has higher working efficiency, more reliable action, and fewer failures, so the size can be made smaller, saving space.

[0004] The utility model patent with announcement number CN209077760U discloses a brake structure of a two-plate die-casting machine, including a brake frame, a brake cylinder and a brake block, a guide column is inserted into the brake frame, the brake block is slidably arranged on the brake frame, and the brake cylinder drives the brake block to slide back and forth relative to the brake frame to hold the guide column or detach from the guide column; it also includes a limit bumper, a first proximity switch, a second proximity switch and a limit indicator rod, the first proximity switch and the second proximity switch are respectively fixed relative to the brake frame, and the limit bumper and the limit indicator rod are respectively fixed relative to the brake block; when the brake block slides to hold the guide column, the limit bumper touches the first proximity switch; when the brake block slides to a certain position away from the guide column, the limit indicator rod touches the second proximity switch; when the system on the two-plate die-casting machine receives the feedback signal of the first proximity switch or the second proximity switch, the system controls the brake cylinder to stop working. The utility model has the characteristics of simple and reasonable structure, reliable and stable performance, and precise positioning.

[0005] However, the brake structure of the above-mentioned die-casting machine still has the problem of poor transmission of driving force, which causes the brake piece to jam and misalign, and aggravates the wear and aging of components. Utility Model Content

[0006] The utility model aims to provide a rear brake structure of a large die-casting machine with a simple structure and precise operation, wherein the brake process runs more stably and smoothly, the parts have low wear, long service life and higher working efficiency.

[0007] The technical solution adopted by the utility model to achieve the above-mentioned purpose is:

[0008] A rear brake structure of a large die-casting machine comprises two brake pads arranged opposite to each other, the brake pads and the opening and closing oil cylinders are arranged one by one, and the operation of the opening and closing oil cylinders can drive the two brake pads to move closer to or away from each other; arc-shaped slots are arranged at opposite ends of the two brake pads, and when the two brake pads are in contact, the two arc-shaped slots cooperate to form a through-hole structure; first teeth are arranged on the inner wall of the arc-shaped slot; the cross section of the first teeth along the axial direction of the arc-shaped slot, that is, along the length direction of the brake pad, is rectangular, and the root of the first teeth is provided with chamfers or fillets;

[0009] Furthermore, two oppositely arranged brake pieces are arranged around the outside of the large bar, that is, the large bar is inserted into the space formed by two oppositely arranged arc-shaped slots on the two brake pieces, and the two brake pieces are close to each other to clamp the large bar. The outer side of the large bar is provided with second teeth, and when the two brake pieces are close to each other and fit with the large bar, the second teeth can mesh with the first teeth.

[0010] The output end of the opening and closing oil cylinder is equipped with a piston rod, and the end of the piston rod away from the closing oil cylinder is connected to the brake pad; the end of the piston rod away from the closing oil cylinder is equipped with a connecting block, and the connecting block is connected to the outer wall of the brake pad.

[0011] The above technical solution is adopted, and the operation of the two brake pads is controlled by the relatively arranged opening and closing cylinders to achieve the tightening of the large lever, making the braking process more stable and smooth. The tooth shape of the first tooth adopts a rectangular tooth, and a chamfer or a rounded corner is provided at the root of the tooth, so that the force cross-section of the first tooth when it is subjected to the axial force of the large lever during the meshing process with the second tooth is rectangular, which reduces the radial force on the first tooth. The first tooth is not easy to be damaged and has a longer service life than the sawtooth tooth. There is a straight tooth contact between the brake pad and the large lever, the action process of the brake is smoother, there are fewer failures, and the work efficiency is higher.

[0012] In addition, the piston rod cooperates with the brake pad through the connecting block, which can reduce the sense of frustration of the brake pad operation when the opening and closing cylinder is started or closed, improve the stability of the brake pad operation, and reduce the wear of the brake pad during operation. The setting of the piston rod is not only used to transmit the power of the opening and closing cylinder to the brake pad and drive the brake pad to move back and forth, but also provides a guiding role during the movement of the brake pad, improves the accuracy of the running direction of the brake pad, ensures that the two relatively set brake pads exert the same force on the large bar, and the large bar is balanced in force, which can also ensure that the multiple first teeth on the two brake pads are balanced in force, further reducing the wear of the first teeth.

[0013] According to an implementation mode of the present invention, an outer side wall of the gate piece is provided with a mounting groove, and the connecting block is arranged inside the mounting groove.

[0014] According to one embodiment of the utility model, the connecting block is a multi-layer structure, including a fixed layer and a contact layer connected inside and outside, the end of the fixed layer away from the contact layer is embedded in the interior of the mounting groove and connected to the outer wall of the gate piece, the contact layer is exposed outside the mounting groove and cooperates with the piston rod.

[0015] Furthermore, the contact layer may be made of a material with a certain degree of flexibility, such as silicone, rubber, etc.

[0016] Therefore, in the process of the piston rod transmitting power to the brake pad, the connecting block realizes a buffering effect, which can prevent the brake pad from getting stuck, misaligned or tilted due to sudden imbalance of force when it starts to move or stops moving due to force changes, thereby improving the stability of the braking process.

[0017] In addition, since the piston rod is indirectly connected to the brake pad through the connecting block, it also helps to reduce noise. The connection block replaces the embedded connection between the end of the piston rod and the brake pad. The two are not in direct contact, which can also prevent the piston rod from suddenly receiving the thrust of the opening and closing cylinder or the thrust suddenly withdrawing. The end of the piston rod produces abnormal noise or friction, which helps to prevent the piston rod from being misplaced or deflected.

[0018] According to an implementation mode of the utility model, two gate pieces cooperate with the limiting assembly at the same time to limit and guide the operation direction of the gate pieces; the limiting assembly includes limiting plates arranged at both ends of the gate pieces, and the gate pieces cooperate movably with the limiting plates.

[0019] Furthermore, a through hole is provided in the middle of the limiting plate, which is a ring-shaped structure, and the large bar can be inserted into the through hole.

[0020] In this way, the limiting plate can be used to limit the two brake pads to move only in the horizontal direction, approaching or moving away from each other, thereby achieving the braking of the large bar; and the brake pads can be prevented from moving up and down and being misplaced during the movement.

[0021] According to an implementation mode of the present invention, a slide groove is arranged at one end of the limiting plate facing the gate piece, and a protrusion is arranged at the end surface of the gate piece, and the protrusion is slidably matched with the slide groove.

[0022] In this way, the gate piece slides with the two upper and lower limit plates during movement, which can limit the gate piece and guide it at the same time. This not only reduces the resistance during the movement of the gate piece, but also improves the accuracy of the moving direction of the gate piece.

[0023] According to an embodiment of the utility model, the limiting assembly includes two limiting arc plates arranged opposite to each other, and the two limiting arc plates are symmetrically arranged on the peripheries of the two brake pieces; and the two piston rod sleeves are respectively and correspondingly arranged inside the two arc plates.

[0024] Furthermore, the curvature of the limiting arc plate matches the curvature of the outer side wall of the gate piece.

[0025] In this way, the two relatively arranged limit arc plates can prevent the gate piece from moving outward excessively, thereby limiting the range of movement of the gate piece. The sleeve structure of the piston rod and the limit arc plate also limits and guides the operating direction of the piston rod, ensuring the accuracy of the running track of the gate piece.

[0026] According to one implementation mode of the utility model, the gate pad cooperates with the electric eye sensing rod, the sensing end of the electric eye sensing rod is arranged opposite to the gate pad, and is used to monitor the position of the gate pad; the electric eye sensing rod is connected to the control system, and the control system controls the operation of the opening and closing cylinder according to the information feedback from the electric eye sensing rod.

[0027] Furthermore, the opening and closing cylinder is connected to the hydraulic system, the hydraulic system is connected to the control system, and the control center controls the operation of the hydraulic system to achieve regulation of the operating state of the opening and closing cylinder.

[0028] Furthermore, the electric eye sensing rod and the proximity switch are arranged in a one-to-one correspondence, the proximity switch is fixedly arranged on the outer wall of the limit arc plate, and the proximity switch is connected to the electric eye sensing rod and the control system respectively, and the proximity switch can receive the position information detected by the electric eye sensing rod and feed the information back to the control system. After receiving the information fed back by the proximity switch, the control system controls the hydraulic system to adjust the operating state of the opening and closing cylinder. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of a top view of a rear brake structure of a large die-casting machine according to an embodiment of the utility model;

[0030] Figure 2 for Figure 1 The schematic cross-sectional structure diagram of the rear brake structure of the large die-casting machine along the AA line is shown;

[0031] Figure 3 for Figure 2 A schematic diagram of the partial enlarged structure of the first tooth in the B area of ​​the middle brake pad;

[0032] Figure 4 for Figure 2 Schematic diagram of the partial enlarged structure of part C in the middle.

[0033] Reference numerals: brake pad 10; first tooth 11; mounting groove 12; opening and closing cylinder 13; piston rod 14; connecting block 15; fixing layer 16; contact layer 17; electric eye sensing rod 18; proximity switch 19; limit plate 21; limit arc plate 22. DETAILED DESCRIPTION

[0034] The technical solution of the utility model is further described in detail below in combination with the specific implementation mode and the accompanying drawings. It should be understood that the specific embodiments described here are only used to explain the utility model, and are not used to limit the utility model.

[0035] Example 1

[0036] Figure 1~Figure 4 The rear brake structure of a large die-casting machine according to an embodiment of the utility model is schematically shown. As shown in the figure, the device includes a limit frame, and the limit frame includes two limit plates 21 arranged opposite to each other up and down, and two limit arc plates 22 arranged opposite to each other left and right. The two limit arc plates 22 are connected by relatively arranged connecting plates, and the limit plates 21, the limit arc plates 22 and the connecting plates are connected to each other to form a box-like or box-like structure with a hollow interior. Among them, a through hole is provided in the middle of the limit plate 21, which is a ring structure, and a large bar can be inserted into the inside of the through hole.

[0037] The interior of the limit frame is provided with two brake pieces 10 arranged opposite to each other. The brake pieces 10 are arranged one by one with the opening and closing oil cylinders 13. The operation of the opening and closing oil cylinders 13 can drive the two brake pieces 10 to move closer to each other or away from each other. The opposite ends of the two brake pieces 10 are provided with arc-shaped slots. When the two brake pieces 10 are in contact, the two arc-shaped slots cooperate to form a through-hole structure; the two brake pieces 10 arranged opposite to each other are arranged around the outside of the large bar, that is, the large bar is inserted into the space formed by the two arc-shaped slots arranged opposite to each other on the two brake pieces 10, and the two brake pieces 10 are close to each other to clamp the large bar.

[0038] The main structure of the opening and closing oil cylinder 13 is arranged outside the limit arc plate 22, and the output end of the opening and closing oil cylinder 13 is provided with a piston rod 14, and the end of the piston rod 14 away from the closing oil cylinder 13 passes through the limit arc plate 22 and is connected to the gate plate 10. Specifically, the limit arc plate 22 is provided with a guide hole, and the piston rod 14 is inserted inside the guide hole. The end of the piston rod 14 away from the closing oil cylinder 13 is provided with a connecting block 15, and the connecting block 15 is connected to the outer wall of the gate plate 10.

[0039] In this way, the operation of the two brake pads 10 is controlled by the relatively arranged opening and closing cylinders 13, so as to achieve the tightening of the large lever and make the braking process more stable and smooth. The piston rod 14 cooperates with the brake pad 10 through the connecting block 15, which can reduce the sense of frustration of the operation of the brake pad 10 when the opening and closing cylinder 13 is started or closed, improve the stability of the operation of the brake pad 10, and reduce the wear of the brake pad 10 during operation. The setting of the piston rod 14 is not only used to transmit the power of the opening and closing cylinder 13 to the brake pad 10 and drive the brake pad 10 to move back and forth, but also to provide a guiding effect during the movement of the brake pad 10, improve the accuracy of the running direction of the brake pad 10, ensure that the two relatively arranged brake pads 10 exert the same force on the large lever, and the large lever is balanced in force, and can also ensure that the multiple first teeth 11 on the two brake pads 10 are balanced in force, further reducing the wear of the first teeth 11.

[0040] The outer side wall of the brake pad 10 is provided with a mounting groove 12, and the connecting block 15 is arranged inside the mounting groove 12. Further, the connecting block 15 can be set as a multi-layer structure, including a fixing layer 16 and a contact layer 17 connected inside and outside, and one end of the fixing layer 16 away from the contact layer 17 is embedded in the inside of the mounting groove 12 and connected to the outer side wall of the brake pad 10, and the contact layer 17 is exposed outside the mounting groove 12 and cooperates with the piston rod 14.

[0041] Furthermore, the contact layer 17 may be made of a material with a certain degree of flexibility, such as silicone, rubber, etc.

[0042] Therefore, in the process of the piston rod 14 transmitting power to the brake pad 10, the connecting block 15 realizes a buffering effect, which can prevent the brake pad 10 from getting stuck, misaligned or tilted due to sudden imbalance of force when it starts to move or stops moving due to force changes, thereby improving the stability of the braking process.

[0043] Furthermore, since the piston rod 14 is indirectly connected to the brake pad 10 through the connecting block 15, it is also helpful to reduce noise. The connection block 15 replaces the embedded connection mode between the end of the piston rod 14 and the brake pad 10, and the two are not in direct contact, which can also prevent the piston rod 14 from generating abnormal noise or friction when the piston rod 14 suddenly receives the thrust of the opening and closing cylinder 13 or the thrust is suddenly withdrawn, which helps to prevent the piston rod 14 from being misplaced or deflected.

[0044] In addition, two gate pieces 10 are arranged inside the limiting frame, and two relatively arranged limiting plates 21 and two relatively arranged limiting arc plates 22 form a limiting assembly for the gate pieces 10. The two gate pieces 10 cooperate with the limiting assembly at the same time, and are used to limit and guide the operating direction of the gate pieces 10; the limiting assembly includes limiting plates 21 arranged at both ends of the gate pieces 10, and the gate pieces 10 and the limiting plates 21 are movably matched. Specifically, the limiting plate 21 is provided with a slide groove at one end facing the gate piece 10, and the end face of the gate piece 10 is provided with a protrusion, and the protrusion is slidably matched with the slide groove. The slide groove can be arranged along the moving direction of the gate piece 10, which is helpful to guide the moving direction of the gate piece 10 and improve the brake accuracy. The curvature of the limiting arc plate 22 is adapted to the curvature of the outer wall of the gate piece 10.

[0045] In this way, the limiting plate 21 can be used to limit the two brake pads 10 to move only in the horizontal direction, approaching or moving away from each other, so as to achieve the brake of the large bar; it can prevent the brake pad 10 from moving up and down and being misplaced during the movement. During the movement, the brake pad 10 slides with the two limiting plates 21 arranged above and below, which can not only limit the position of the brake pad 10 but also guide the brake pad 10. In this way, it can not only reduce the resistance during the movement of the brake pad 10, but also improve the accuracy of the moving direction of the brake pad 10. The two limiting arc plates 22 arranged relatively to each other can prevent the brake pad 10 from moving excessively outward, so as to limit the moving range of the brake pad 10. The sleeve structure of the piston rod 14 and the limiting arc plate 22 also limits and guides the operating direction of the piston rod 14, thereby ensuring the accuracy of the running trajectory of the brake pad 10.

[0046] Furthermore, the inner wall of the arc-shaped slot is provided with a first tooth 11; the cross section of the first tooth 11 along the axial direction of the arc-shaped slot, that is, along the length direction of the brake pad 10 is rectangular, and the root of the first tooth 11 is provided with a chamfer or a fillet; the outer side of the large bar is provided with a second tooth, and when the two brake pads 10 are close to each other and fit with the large bar, the second tooth can mesh with the first tooth 11. The tooth shape of the first tooth 11 adopts a rectangular tooth, and a chamfer or a fillet is provided at the root, so that the force cross section of the first tooth 11 when it is subjected to the axial force of the large bar during the meshing process with the second tooth is rectangular, which reduces the radial force of the first tooth 11, and the first tooth 11 is not easy to be damaged, and has a longer service life than the sawtooth tooth. There is a straight tooth contact between the brake pad 10 and the large bar, and the action process of the brake is smoother, with fewer failures and higher work efficiency.

[0047] The gate piece 10 cooperates with the electric eye sensing rod 18, and the sensing end of the electric eye sensing rod 18 is arranged opposite to the gate piece 10, which is used to monitor the position of the gate piece 10; the electric eye sensing rod 18 is connected to the control system, and the control system controls the operation of the opening and closing cylinder 13 according to the information fed back by the electric eye sensing rod 18. In order to improve the accuracy of the gate piece 10 during movement, each gate piece 10 can be provided with two electric eye sensing rods 18, and the two electric eye sensing rods 18 are symmetrically arranged on the upper and lower sides of the corresponding piston rod 14, so that the position of the upper and lower halves of the gate piece 10 can be monitored in real time through the electric eye sensing rod 18, so as to monitor the state of the gate piece 10 during movement in real time, and the situation can be discovered in time when an accident occurs and responded to at the first time.

[0048] Furthermore, the opening and closing cylinder 13 is connected to the hydraulic system through a pipeline, and the hydraulic system is connected to the control system. The control center controls the operation of the hydraulic system, adjusts the oil pressure inside the opening and closing cylinder 13, and realizes the regulation of the operating state of the opening and closing cylinder 13.

[0049] Furthermore, the electric eye sensing rod 18 and the proximity switch 19 are arranged in a one-to-one correspondence, the proximity switch 19 is fixedly arranged on the outer wall of the limit arc plate 22, and the proximity switch 19 is respectively connected to the electric eye sensing rod 18 and the control system, and the proximity switch 19 can receive the position information detected by the electric eye sensing rod 18 and feed the information back to the control system. After receiving the information fed back by the proximity switch 19, the control system controls the hydraulic system to adjust the operating state of the opening and closing cylinder 13.

[0050] For example, when the brake is engaged, the control system regulates the operation of the hydraulic system, and then regulates the two opening and closing cylinders 13 to operate synchronously, driving the two brake pads 10 to move in the same direction. During this process, the electric eye sensor rod 18 monitors the position of the brake pads 10. When the two brake pads 10 move relative to each other and reach the limit position, the proximity switch 19 receives the position data detected by the electric eye sensor rod 18, and feeds the data back to the control system. After analyzing the data, the control system issues a stop operation command to the hydraulic system. The hydraulic system regulates the two opening and closing cylinders 13 to stop operating synchronously, and the two brake pads 10 stop moving and stop engaging the brake. The two brake pads 10 fit tightly with the large bar, and the first teeth 11 mesh with the second teeth. At this time, the rear brake structure can lock the large bar and the tail plate (not shown in the figure).

[0051] Correspondingly, after the brake process is completed, the control system controls the operation of the hydraulic system, and then controls the two opening and closing cylinders 13 to operate synchronously, driving the two brake pads 10 to move in the opposite direction. During this process, the electric eye sensor rod 18 continues to monitor the position of the brake pads 10. When the two brake pads 10 move in the opposite direction and reach the limit position, the proximity switch 19 receives the position data detected by the electric eye sensor rod 18 and feeds the data back to the control system. After analyzing the data, the control system issues a stop operation command to the hydraulic system. The hydraulic system controls the two opening and closing cylinders 13 to stop operating synchronously, and the two brake pads 10 stop moving.

[0052] The data information of the limit position of the brake pad 10 moving inward and outward can be input into the system in advance, which is convenient for the accuracy of the monitoring of the electric eye sensing rod 18. The control system is electrically connected to the hydraulic system, and the hydraulic system is connected to the oil circuit of the opening and closing cylinder 13 through a pipeline, so that the control system and the hydraulic system can be structurally separated from the limit frame and the brake pad 10 and the opening and closing cylinder 13 inside it, thereby reducing the interference inside the equipment and ensuring the smooth operation of the brake.

[0053] In addition, an air flow channel may be configured inside the gate piece 10, which passes through both ends of the gate piece 10 longitudinally and can be connected to the space outside the gate piece 10 laterally. In this way, the air pressure at both ends of the gate piece 10 can be kept consistent during the inward or outward movement of the gate piece 10, which can further improve the stability of the gate piece 10 during movement and prevent the gate piece 10 from bending, deforming, tilting or bumping during movement.

[0054] The conventional operations in the operating steps of the present invention are well known to those skilled in the art and will not be described in detail here.

[0055] The embodiments described above provide a detailed description of the technical solution of the utility model. It should be understood that the above is only a specific embodiment of the utility model and is not intended to limit the utility model. Any modifications, supplements or similar substitutions made within the scope of the principles of the utility model should be included in the protection scope of the utility model.

Claims

1. A rear brake structure of a large die-casting machine, characterized in that: The invention comprises two brake pads (10) arranged opposite to each other, wherein the brake pads (10) and the opening and closing oil cylinders (13) are arranged one by one, and the operation of the opening and closing oil cylinders (13) can drive the two brake pads (10) to move closer to each other or away from each other; arc-shaped grooves are provided at opposite ends of the two brake pads (10); when the two brake pads (10) are in contact, the two arc-shaped grooves cooperate to form a through-hole structure; the inner wall of the arc-shaped groove is provided with a first tooth (11); the first tooth (11) has a rectangular cross section, and the root of the first tooth (11) is provided with a chamfer or a rounded corner; The output end of the opening and closing oil cylinder (13) is provided with a piston rod (14), and the end of the piston rod (14) away from the opening and closing oil cylinder (13) is connected to the gate plate (10); the end of the piston rod (14) away from the opening and closing oil cylinder (13) is provided with a connecting block (15), and the connecting block (15) is connected to the outer wall of the gate plate (10); the outer wall of the gate plate (10) is provided with a mounting groove (12), and the connecting block (15) is arranged inside the mounting groove (12).

2. The rear brake structure of a large die-casting machine according to claim 1, characterized in that: The connecting block (15) is a multi-layer structure, comprising a fixing layer (16) and a contact layer (17) connected inside and outside, wherein one end of the fixing layer (16) away from the contact layer (17) is embedded in the interior of the mounting groove (12) and connected to the outer side wall of the brake pad (10), and the contact layer (17) is exposed outside the mounting groove (12) and cooperates with the piston rod (14).

3. The rear brake structure of a large die-casting machine according to claim 1, characterized in that: The two gate pieces (10) cooperate with the limiting assembly to limit and guide the operating direction of the gate pieces (10); The limiting assembly comprises limiting plates (21) arranged at both ends of the gate piece (10), and the gate piece (10) is movably matched with the limiting plates (21).

4. The rear brake structure of a large die-casting machine according to claim 3, characterized in that: The limiting plate (21) is provided with a sliding groove at one end facing the gate piece (10), and the end surface of the gate piece (10) is provided with a protrusion, and the protrusion is slidably matched with the sliding groove.

5. The rear brake structure of a large die-casting machine according to claim 3, characterized in that: The limiting assembly comprises two limiting arc plates (22) arranged opposite to each other, wherein the two limiting arc plates (22) are symmetrically arranged on the peripheries of the two brake pads (10); and the two piston rod (14) sleeves are respectively and correspondingly arranged inside the two arc plates.

6. The rear brake structure of a large die-casting machine according to claim 1, characterized in that: The gate piece (10) cooperates with an electric eye sensing rod (18), and a sensing end of the electric eye sensing rod (18) is arranged opposite to the gate piece (10) for monitoring the position of the gate piece (10); The electric eye sensing rod (18) is connected to a control system, and the control system controls the operation of the opening and closing oil cylinder (13) according to information fed back by the electric eye sensing rod (18).

7. The rear brake structure of a large die-casting machine according to claim 6, characterized in that: The opening and closing oil cylinder (13) is connected to a hydraulic system, the hydraulic system is connected to the control system, and the control system controls the operation of the hydraulic system to achieve regulation of the operating state of the opening and closing oil cylinder (13).

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