Rotary table brake device and machine tool

Abstract

The utility model relates to the field of machine tools, in particular to a rotary table brake device and a machine tool, the rotary table brake device comprises a base, a rotating shaft, a working table, a brake assembly, a braking oil way and a reset structure, the brake assembly comprises a brake disc, a brake cylinder body, a brake piston and a brake pad, and a cavity is formed between the brake disc and the brake cylinder body; the brake piston is located in the cavity and divides the cavity into a first cavity and a second cavity which are not communicated, a preset gap is formed between the upper end of the brake disc and the lower side portion of the brake piston, one side of the brake pad is fixed to the rotating shaft, and the other side of the brake pad is located in the preset gap. The braking oil way is communicated with the first cavity to achieve braking of the rotary table, the reset structure is located in the second cavity or connected with the second cavity to achieve reset after braking, the rotary table braking device is simple and compact in overall structure, accurate braking can be achieved during braking, rapid and stable recovery can be achieved during resetting, and the service life of the rotary table is prolonged. And the stability and reliability of machine tool turntable operation are effectively improved.

Description

Technical Field

[0001] This utility model relates to the field of machine tools, and more specifically, to a rotary table braking device and a machine tool. Background Technology

[0002] In the machine tool industry, the structural design of the hydraulic braking system of a machine tool's rotary table directly affects the machine tool's braking stability and machining accuracy. Traditional rotary table braking systems mainly consist of pneumatic braking structures composed of clamps. However, in large rotary tables, using a braking system composed of clamps and brake shafts results in high clamp costs, and pneumatic clamp braking is unstable. Therefore, the structural design of the machine tool's rotary table braking system directly affects the machine tool's braking stability and machining accuracy. Utility Model Content

[0003] The purpose of this utility model is to provide a turntable braking device and machine tool. By utilizing the stable pressure transmission characteristics of the hydraulic system and combining the designed braking components, brake oil circuit and reset structure, it effectively solves the problems of high cost and unstable braking of traditional pneumatic braking structures.

[0004] To achieve the above objectives, this utility model provides the following technical solution:

[0005] On one hand, the present invention provides a turntable braking device, comprising: a base, a rotating shaft rotatably disposed within the base, and a worktable fixedly disposed above the rotating shaft. The device is characterized by further comprising a braking assembly, a braking oil circuit, and a reset structure. The braking assembly includes a brake disc, a brake cylinder, a brake piston, and brake pads. The brake disc is fixedly disposed above the base, and the brake cylinder is fixedly disposed above the brake disc. A cavity is formed between the brake disc and the brake cylinder. The brake piston is located within the cavity and divides the cavity into a non-communicating first chamber and a second chamber. A radial limiting structure is provided between the brake piston and the brake cylinder. A preset gap exists between the upper end of the brake disc and the lower side of the brake piston. One side of the brake pad is fixed to the rotating shaft, and the other side of the brake pad is located within the preset gap. The worktable covers the upper part of the brake cylinder.

[0006] The first chamber is located between the brake cylinder and the brake piston, the second chamber is located between the brake disc and the brake piston, the brake tightening oil circuit is disposed on the base, and the brake tightening oil circuit communicates with the first chamber through the brake disc and the brake cylinder, the reset structure is located in or connected to the second chamber, and the reset structure is used to push the brake piston to keep the brake piston and the brake disc at a preset gap.

[0007] In some embodiments, the reset structure includes a release oil passage disposed on the base, and the release oil passage passes through the brake disc and communicates with the second chamber.

[0008] In some embodiments, the reset structure includes an elastic structure disposed within the second chamber, wherein the elastic structure comprises a plurality of elastic structures, which are evenly distributed along the circumference of the second chamber.

[0009] In some embodiments, the vertical height of the second chamber is greater than the vertical height from the lower end of the brake piston to the upper end of the brake pad within the preset gap.

[0010] In some embodiments, annular sealing structures are provided between the inner periphery of the brake cylinder and the outer periphery of the brake piston, and between the inner periphery of the brake piston and the brake disc and the brake cylinder, respectively, and the annular sealing structures separate the first chamber and the second chamber.

[0011] In some embodiments, a skeleton oil seal is provided between the top of the outer periphery of the brake cylinder and the inner periphery of the worktable; the radial limiting structure includes multiple structures, and the inner periphery of the brake cylinder is provided with multiple axial grooves that match the radial limiting structure. The radial limiting structure is disposed in the axial groove, and the multiple radial limiting structures are evenly distributed along the outer periphery of the brake piston.

[0012] In some embodiments, the braking oil passage and the releasing oil passage are evenly distributed along the circumference of the base, and there are at least three braking oil passages and at least three releasing oil passages.

[0013] In some embodiments, the turntable braking device further includes a bearing disposed between the base and the rotating shaft. The bearing has an outer bearing ring and an inner bearing ring that are rotatable relative to each other. The outer bearing ring is fixedly connected to the base, and the inner bearing ring is fixedly connected to the rotating shaft.

[0014] On the other hand, this utility model provides a machine tool, including the aforementioned rotary table braking device, which is disposed on the machine bed.

[0015] In some embodiments, the machine tool further includes a hydraulic station and hydraulic valves. The hydraulic station is connected to the braking and releasing oil circuits of the turntable braking device via the hydraulic valves. The hydraulic valves are used to control the oil inlet and outlet of the braking and releasing oil circuits.

[0016] The beneficial effects of this utility model are as follows: The rotary table braking device of this utility model, through the designed braking components, evenly distributed braking oil circuit and reset structure, enables the rotary table braking device to achieve precise braking during braking, and the braking force during braking is adjustable. It can also quickly and stably recover during reset, effectively improving the stability and reliability of the machine tool rotary table operation. At the same time, the overall structure of the rotary table braking device is simple and compact, the component cost is low and the hydraulic components can be selected in a variety of ways, effectively reducing procurement and maintenance costs. Attached Figure Description

[0017] The present invention will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings:

[0018] Figure 1 This is a sectional view of the turntable braking device of this utility model;

[0019] Figure 2 This is a partial schematic diagram of the cross-sectional view of the turntable braking device of this utility model;

[0020] Figure 3 This is a top view of the brake assembly in the turntable brake device of this utility model;

[0021] Figure 4 This is a cross-sectional view of the turntable braking device of this utility model from another direction;

[0022] Figure 5 This is a cross-sectional view of the turntable braking device of this utility model.

[0023] The attached figures are labeled as follows:

[0024] 1-Base, 2-Rotating shaft, 3-Worktable, 4-Brake assembly, 5-Brake tightening oil circuit, 6-Reset structure, 7-Bearing, 41-Brake disc, 42-Brake cylinder body, 43-Brake piston, 44-Brake pad, 45-Annular sealing structure, 46-Skeleton oil seal, 61-Release oil circuit, 62-Elastic structure, 71-Bearing outer ring, 72-Bearing inner ring, 431-First chamber, 432-Second chamber, 433-Radial limiting structure, 434-Preset gap, 435-Axial groove Detailed Implementation

[0025] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present invention.

[0026] It should be noted that in the description of this utility model, the orientation descriptions, such as up, down, front, back, left, right, etc., are based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0027] In the description of this utility model, "several" means one or more, "multiple" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. If "first" or "second" is used in the description, it is only for the purpose of distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0028] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" and "second" may explicitly or implicitly include one or more features.

[0029] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the term "connection" should be interpreted broadly. For example, it can be a fixed connection or a movable connection, a detachable connection or a non-detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection or a connection that can communicate with each other; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two elements, an indirect connection, or an interaction between two elements.

[0030] The following disclosure provides many different implementation methods or examples for different solutions to implement this utility model.

[0031] like Figures 1 to 5As shown, the turntable braking device provided by this utility model includes a base 1, a rotating shaft 2 rotatably disposed within the base 1, and a worktable 3 fixedly disposed above the rotating shaft 2. The worktable 3 is used to mount workpieces for the required processing. The turntable braking device also includes a brake assembly 4, a brake oil circuit 5, and a reset structure 6. The brake assembly 4 includes a brake disc 41, a brake cylinder 42, a brake piston 43, and brake pads 44. The brake disc 41 is fixedly disposed above the base 1, and the brake cylinder 42 is fixedly disposed above the brake disc 41. A cavity is formed between the brake disc 41 and the brake cylinder 42. The brake piston 43 is located within the cavity and divides the cavity into a non-communicating first chamber 431 and a second chamber 432. A connection is provided between the brake piston 43 and the brake cylinder 42. The system has a radial limiting structure 433, a preset gap 434 between the upper end of the brake disc 41 and the lower side of the brake piston 43, one side of the brake pad 44 is fixed on the rotating shaft 2, and the other side of the brake pad 44 is located within the preset gap 434. The worktable 3 is placed above the brake cylinder body 42. The first chamber 431 is located between the brake cylinder body 42 and the brake piston 43, and the second chamber 432 is located between the brake disc 41 and the brake piston 43. The brake tightening oil passage 5 is provided on the base 1 and is connected to the first chamber 431 through the brake disc 41 and the brake cylinder body 42. The reset structure 6 is located in or connected to the second chamber 432. The reset structure 6 is used to push the brake piston 43 so that the brake piston 43 and the brake disc 41 maintain the preset gap 434.

[0032] The base 1 serves as the mounting foundation for the entire turntable braking device. The rotating shaft 2 enables the turntable to rotate, and the worktable 3 is a work platform for carrying various processed parts. The brake disc 41 is fixedly mounted above the base 1 and provides a braking friction surface for the brake pads 44. The brake cylinder 42 is fixedly mounted above the brake disc 41, forming a cavity between the brake disc 41 and the brake cylinder 42 to accommodate the up-and-down movement of the brake piston 43 within the cavity. The brake piston 43, as the direct component for braking, is located within the cavity and divides the cavity into a non-communicating first chamber 431 and a second chamber 432. One side of the brake pads 44 is fixed to the rotating shaft 2 and can move synchronously with the rotation of the rotating shaft 2. The other side is located within a preset gap 434 between the upper end of the brake disc 41 and the lower part of the brake piston 43. Under normal conditions, the brake pads 44 and the brake disc 41 maintain a certain gap, allowing the rotating shaft 2 to rotate freely.

[0033] Meanwhile, the braking oil circuit 5 is located on the base 1 for easy connection to the hydraulic oil source. The braking oil circuit 5 connects to the first chamber 431 via the brake disc 41 and the brake cylinder 42. When the braking oil circuit 5 delivers hydraulic oil into the first chamber 431 and it accumulates rapidly, the hydraulic oil exerts pressure on the brake piston 43, causing the brake piston 43 to move downward along the axial direction. The brake piston 43 squeezes the brake pads, causing the brake pads 44 to approach and press against the brake disc 41, thereby generating sufficient friction to prevent the rotating shaft 2 from rotating and stably achieving braking of the turntable. The reset structure 6 is located in or connected to the second chamber 432. After the braking action is completed, the reset structure can push the brake piston 43 upward to maintain a preset gap 434 between the brake piston 43 and the brake disc 41, so that the turntable can smoothly resume rotation. During the operation of the turntable braking device, the radial limiting structure 433 can effectively reduce the radial offset or sway of the brake piston 43 when it is affected by external force, so that the brake piston 43 can move up and down more accurately along the axial direction, and achieve stable braking and reset actions.

[0034] The reset structure 6 can be implemented in various ways; in some implementations, such as Figure 1 and Figure 2 As shown, the reset structure 6 in this embodiment includes a release oil passage 61, which is disposed on the base 1 and connects the brake disc 41 to the second chamber 432. When a reset operation is required, hydraulic oil begins to enter the second chamber 432 through the release oil passage 61. As the hydraulic oil accumulates in the second chamber 432, it exerts an upward thrust on the lower surface of the brake piston 43. Simultaneously, during the braking process, hydraulic oil flows out of the first chamber 431, which is used to push the brake piston 43 downward to achieve braking, through methods such as oil leakage, causing the pressure to gradually decrease. Under the action of the pressure difference between the upper and lower sides of the hydraulic oil, the brake piston 43 begins to move upward and quickly separates from the brake pad 44. During this process, the gap between the brake piston 43 and the brake disc 41 gradually increases until it returns to the preset gap 434. At this point, the turntable can rotate freely and stably complete the reset operation.

[0035] During braking, the pressure difference between the hydraulic oil in the first chamber 431 and the second chamber 432 directly determines the downward thrust on the brake piston 43. This downward thrust is transmitted to the brake pads 44, which is then converted into friction between the brake pads 44 and the brake disc 41, i.e., the braking force. When a greater braking force is required, the flow rate and pressure of the braking oil circuit 5 or the releasing oil circuit 61 can be adjusted bidirectionally to further increase the pressure of the hydraulic oil in the first chamber 431 or decrease the pressure of the hydraulic oil in the second chamber 432, thereby increasing the pressure difference between the first chamber 431 and the second chamber 432 and achieving the purpose of increasing the braking force.

[0036] In some implementations, such as Figure 1 , Figure 2 and Figure 4 As shown, the reset structure 6 includes an elastic structure 62 disposed within the second chamber 432. Multiple elastic structures 62 are evenly distributed along the circumference of the second chamber 432. When the turntable is in a braking state, the brake piston 43 moves downwards under the pressure of hydraulic oil, compressing the elastic structures 62 within the second chamber 432. When the braking action is completed and a reset operation is performed, the compressed elastic structures 62 utilize their stored elastic potential energy to push the brake piston 43 upwards, quickly separating from the brake pads 44. During this process, the gap between the brake piston 43 and the brake disc 41 gradually increases until it returns to the preset gap 434. At this point, the turntable can rotate freely, stably completing the reset operation.

[0037] Meanwhile, the elastic structure 62 can be composed of various components with elastic properties. The elastic component 62 can store elastic potential energy when compressed by external force and release the potential energy after the external pressure disappears, restoring its original shape, thereby generating an elastic force to push the brake piston 43 to reset. Multiple elastic structures 62 are evenly distributed along the circumference of the second chamber 432. During the process of the brake piston 43 compressing the elastic structure 62 downward, the evenly distributed elastic structure 62 can make the brake piston 43 experience uniform resistance in the circumferential direction, further making the downward movement of the brake piston 43 more stable, avoiding problems such as piston tilting and jamming caused by uneven local force, and improving the stability of the braking action.

[0038] Ideally, the release oil circuit 61 and the elastic structure 62 can be used simultaneously, working together to improve the turntable's reset performance. Because the hydraulic thrust of the release oil circuit 61 and the elastic force of the elastic structure 62 coexist, even under special circumstances, such as slight fluctuations in the hydraulic system causing instability in the thrust of the release oil circuit 61, or the elasticity of the elastic structure 62 decreasing due to long-term use, the other force can still function, allowing the brake piston 43 to reset smoothly and quickly separate from the brake pad 44, maintaining the gap between the brake piston 43 and the brake disc 41 back to the preset gap 434, ensuring the turntable can rotate freely. Simultaneously, the thrust generated by the hydraulic oil injected through the release oil circuit 61 can be precisely adjusted according to actual conditions. By controlling parameters such as the flow rate and pressure of the hydraulic oil, sufficient upward thrust can be quickly applied to the brake piston 43, achieving rapid initiation of the reset action. The elastic force released by the elastic structure 62 is relatively stable, continuously providing uniform upward assistance throughout the reset process. The combination of the two allows for rapid reset in the initial stage by leveraging the thrust of releasing the oil circuit 61, while the elasticity of the elastic structure 62 ensures the stability of the reset in the subsequent process. This avoids problems such as component impact or vibration that may occur due to excessive reset speed, thus achieving a fast and stable reset operation of the turntable and effectively improving the stability and reliability of the machine tool turntable operation.

[0039] In some implementations, such as Figure 2 As shown, the vertical height of the second chamber 432 is greater than the vertical height from the lower end of the brake piston 43 to the upper end of the brake pad 44 within the preset gap 434. This can prevent the brake piston from contacting the brake disc before contacting the brake pad during braking, thus avoiding the loss of braking.

[0040] In some implementations, such as Figure 2 As shown, annular sealing structures 45 are respectively provided between the inner circumference of the brake cylinder body 42 and the outer circumference of the brake piston 43, and between the inner circumference of the brake piston 43 and the brake disc 41 and the brake cylinder body 42. The annular sealing structures 45 separate the first chamber 431 and the second chamber 432. The annular sealing structure 45 located between the inner circumference of the brake cylinder body 42 and the outer circumference of the brake piston 43 can prevent hydraulic oil from leaking or flowing during the up and down movement of the brake piston 43. The annular sealing structure 45 provided between the inner circumference of the brake piston 43 and the brake disc 41 and the brake cylinder body 42 can further ensure the sealing of the hydraulic oil between the first chamber 431 and the second chamber 43, avoiding unnecessary oil flow.

[0041] In some implementations, such as Figure 2 As shown and Figure 3As shown, a skeleton oil seal 46 is provided between the top of the outer periphery of the brake cylinder body 42 and the inner periphery of the worktable 3. The skeleton oil seal 46 can effectively reduce the entry of external impurities such as dust, metal shavings, and cutting fluid into the brake cylinder body 42, reducing contamination of the hydraulic oil and affecting the normal operation of the hydraulic system. The radial limiting structure 433 can cooperate more precisely with the brake cylinder body 42, enhancing the restriction effect on the radial movement of the brake piston 43. The radial limiting structure 433 includes multiple structures. The inner periphery of the brake cylinder body 42 is provided with multiple axial grooves 435 that match the radial limiting structure 433. The radial limiting structure 433 is set in the axial grooves 435. The multiple radial limiting structures 433 are evenly distributed along the outer periphery of the brake piston 43, so that the radial limiting structure 433 can cooperate more precisely with the brake cylinder body 42. This ensures that when the brake piston 43 is subjected to force, the radial limiting force on each part of its circumference is uniform, further improving the straightness and stability of the brake piston 43 during axial movement.

[0042] In some implementations, such as Figure 4 As shown, the braking hydraulic lines 5 and 61 are evenly distributed along the circumference of the base 1, with at least three braking hydraulic lines 5 and at least three 61. The even distribution of at least three braking hydraulic lines 5 allows hydraulic oil to enter the first chamber 431 simultaneously through multiple evenly distributed paths. This makes the pressure exerted by the hydraulic oil on the upper surface of the brake piston 43 more uniform in the circumferential direction, reducing uneven force on the brake piston 43 caused by excessive or insufficient local pressure. This, in turn, affects the uniformity of contact and the stability of friction between the brake pads 44 and the brake disc 41, effectively improving the stability and reliability of the brakes and ensuring that the turntable can stop rotating smoothly and quickly. Similarly, the even distribution of at least three 61 circumferential paths allows hydraulic oil to enter the second chamber 432 simultaneously through multiple evenly distributed paths. This makes the upward thrust exerted by the hydraulic oil on the lower surface of the brake piston 43 more uniform in the circumferential direction, ensuring that the brake piston 43 can return to its original position smoothly and quickly.

[0043] In some implementations, such as Figure 4 As shown, the turntable braking device also includes a bearing 7, which is disposed between the base 1 and the rotating shaft 2. The bearing 7 has an outer bearing ring 71 and an inner bearing ring 72 that can rotate relative to each other. The outer bearing ring 71 is fixedly connected to the base 1, so that the position of the bearing 7 on the base 1 is relatively fixed, providing stable support for the normal operation of the entire bearing 7. The inner bearing ring 72 is fixedly connected to the rotating shaft 2, so that the bearing 7 can move synchronously with the rotation of the rotating shaft 2.

[0044] In another aspect, this utility model also provides a machine tool, including a bed and a column mounted on the bed, and further including the rotary table braking device described above, wherein the rotary table braking device is mounted on the bed. Since this machine tool has the aforementioned rotary table braking device, it also has the corresponding effect of the rotary table braking device, which will not be described in detail here.

[0045] In some embodiments, the machine tool further includes a hydraulic station and hydraulic valves. The hydraulic station is connected to the braking oil circuit 5 and the releasing oil circuit 61 of the turntable braking device via hydraulic valves. The hydraulic valves control the oil inlet and outlet of the braking oil circuit 5 and the releasing oil circuit 61. The hydraulic station, hydraulic valves, and turntable braking device together constitute a complete hydraulic control system. The hydraulic station is the power core of the entire hydraulic system, providing hydraulic oil with a certain pressure and flow rate to the hydraulic braking device. The hydraulic valves control and coordinate the pressure and flow rate of the oil inlet and outlet of the braking oil circuit 5 and the releasing oil circuit 61, thereby achieving precise braking and resetting and improving the stability and flexibility of braking and resetting.

[0046] Although embodiments of the present invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A turntable braking device, comprising a base (1), a rotating shaft (2) rotatably disposed within the base (1), and a worktable (3) fixedly disposed above the rotating shaft (2), characterized in that, It also includes a brake assembly (4), a brake oil circuit (5), and a reset structure (6). The brake assembly (4) includes a brake disc (41), a brake cylinder (42), a brake piston (43), and brake pads (44). The brake disc (41) is fixedly disposed above the base (1), and the brake cylinder (42) is fixedly disposed above the brake disc (41). A cavity is formed between the brake disc (41) and the brake cylinder (42). The brake piston (43) is located in the cavity and divides the cavity into non-continuous sections. The brake cylinder has a first chamber (431) and a second chamber (432). A radial limiting structure (433) is provided between the brake piston (43) and the brake cylinder (42). A preset gap (434) is provided between the upper end of the brake disc (41) and the lower side of the brake piston (43). One side of the brake pad (44) is fixed on the rotating shaft (2), and the other side of the brake pad (44) is located in the preset gap (434). The worktable (3) is placed on top of the brake cylinder (42). The first chamber (431) is located between the brake cylinder (42) and the brake piston (43), the second chamber (432) is located between the brake disc (41) and the brake piston (43), the brake tightening oil passage (5) is disposed on the base (1), and the brake tightening oil passage (5) communicates with the first chamber (431) through the brake disc (41) and the brake cylinder (42), the reset structure (6) is located in or connected to the second chamber (432), and the reset structure (6) is used to push the brake piston (43) so that the brake piston (43) and the brake disc (41) maintain a preset gap (434).

2. The turntable braking device according to claim 1, characterized in that: The reset structure (6) includes a release oil passage (61), which is disposed on the base (1) and connects the brake disc (41) to the second chamber (432).

3. The turntable braking device according to claim 1 or 2, characterized in that: The reset structure (6) includes an elastic structure (62) disposed in the second chamber (432). The elastic structure (62) includes a plurality of elastic structures (62) which are evenly distributed along the circumference of the second chamber (432).

4. The turntable braking device according to claim 1 or 2, characterized in that: The vertical height of the second chamber (432) is greater than the vertical height from the lower end of the brake piston (43) to the upper end of the brake pad (44) within the preset gap (434).

5. The turntable braking device according to claim 1 or 2, characterized in that: An annular sealing structure (45) is provided between the inner circumference of the brake cylinder (42) and the outer circumference of the brake piston (43), and between the inner circumference of the brake piston (43) and the brake disc (41) and the brake cylinder (42), respectively. The annular sealing structure (45) separates the first chamber (431) and the second chamber (432).

6. The turntable braking device according to claim 1 or 2, characterized in that: A skeleton oil seal (46) is provided between the top of the outer periphery of the brake cylinder (42) and the inner periphery of the worktable (3); the radial limiting structure (433) includes a plurality of them, and the inner periphery of the brake cylinder (42) is provided with a plurality of axial grooves (435) that match the radial limiting structure (433). The radial limiting structure (433) is disposed in the axial groove (435), and the plurality of radial limiting structures (433) are evenly distributed along the outer periphery of the brake piston (43).

7. The turntable braking device according to claim 2, characterized in that: The braking oil passage (5) and the releasing oil passage (61) are evenly distributed along the circumference of the base (1), and there are at least 3 braking oil passages (5) and at least 3 releasing oil passages (61).

8. The turntable braking device according to claim 1 or 2, characterized in that: It also includes a bearing (7), which is disposed between the base (1) and the rotating shaft (2). The bearing (7) has an outer bearing ring (71) and an inner bearing ring (72) that can rotate relative to each other. The outer bearing ring (71) is fixedly connected to the base (1), and the inner bearing ring (72) is fixedly connected to the rotating shaft (2).

9. A machine tool, comprising a bed and a column disposed on the bed, characterized in that, It also includes the turntable braking device as described in any one of claims 1 to 8, wherein the turntable braking device is disposed on the bed.

10. The machine tool according to claim 9, characterized in that, It also includes a hydraulic station and hydraulic valves. The hydraulic station is connected to the brake oil circuit (5) and release oil circuit (61) of the turntable brake device through the hydraulic valves. The hydraulic valves are used to control the oil inlet and outlet of the brake oil circuit (5) and release oil circuit (61).

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