Internal support type self-centering precision casting ball valve clamp

Abstract

The utility model discloses an inner supporting type self-centering precision casting ball valve clamp, and belongs to the technical field of valve body machining equipment. The device comprises a fixing sleeve; a cylinder body of the cylinder is fixed at the bottom of the fixing sleeve, and a piston rod of the cylinder can extend into an inner cavity of the fixing sleeve; the connecting rod mechanisms correspond to the sliding holes in a one-to-one mode, one side end of each connecting rod mechanism is hinged to a piston rod of the air cylinder, and the other side end of each connecting rod mechanism is inserted into the corresponding sliding hole in a sliding mode; the clamping jaw assemblies correspond to the connecting rod mechanisms one to one, each clamping jaw assembly comprises a lifting rod and a clamping assembly, the lifting rods are fixed to the tops of the side ends of the connecting rod mechanisms, and the clamping assemblies are fixed to the upper ends of the lifting rods. According to the device, a workpiece with an irregular outer surface can be clamped, the height of the clamping assembly can be adjusted through the lifting rod to adapt to the size of the workpiece, the clamping stability is improved, the clamping assembly is prevented from being abraded, and the machining precision is prevented from being affected.

Description

Technical Field

[0001] The utility model relates to the technical field of valve body processing equipment, specifically to a valve body fixture, and more specifically to an inner support type self-centering precision casting ball valve fixture. Background Art

[0002] The weight of the precision casting ball valve blank is generally more than one hundred kilograms, and the size deviation is large, and there are many riser features, resulting in the characteristics of difficult precise positioning and large load in the design of the precision casting ball valve fixture. In addition, most of the existing precision casting ball valve fixtures are special fixtures, and one fixture can only meet the clamping of valve bodies of one size specification, without flexible adjustment performance, which is easy to cause waste. See Figure 1 , the riser of the ball valve blank is at one end of the valve body flange surface, and the overall shape is irregular. If an outer clamping fixture is used for clamping, not only the clamping force is uneven, but also the stability is low, which is easy to cause wear to the ball valve.

[0003] Most of the three-jaw chuck self-centering fixtures on the market at present are for clamping and positioning small-diameter workpieces, and generally clamp from the outside of the workpiece. According to the power source, they are divided into manual, pneumatic, electric and hydraulic drive. Generally, through the combination of bevel gear transmission and screw transmission, the jaws are driven to move radially to clamp the workpiece. The advantages are self-centering, high centering accuracy, fast workpiece clamping and simple and convenient operation; high clamping accuracy, uniform clamping force, strong reliability and applicability. Disadvantages: It is impossible to clamp irregular valve bodies with many outer surface features; and as the use time increases, it is easy to wear and cause deformation of the jaw ends, thereby reducing the machining accuracy of the workpiece. Content of the Utility Model

[0004] In view of this, the utility model aims to provide an inner support type self-centering precision casting ball valve fixture to at least solve to a certain extent the technical problems in the prior art that irregular valve bodies with many outer surface features cannot be clamped, and the jaws are easy to wear and deform, thereby reducing the machining accuracy of the workpiece.

[0005] In order to achieve the above purpose, the utility model adopts the following technical scheme:

[0006] An inner support type self-centering precision casting ball valve fixture, comprising:

[0007] A fixed sleeve, on the side wall of which a plurality of sliding holes are circumferentially and evenly spaced;

[0008] A cylinder; the cylinder body of the cylinder is coaxially arranged with the fixed sleeve and fixed at the bottom of the fixed sleeve, and the bottom end of the piston rod of the cylinder is slidably connected in the cylinder body, and the top end extends into the inner cavity of the fixed sleeve;

[0009] A plurality of link mechanisms, the plurality of link mechanisms corresponding to the plurality of the sliding holes one by one, each of the link mechanisms being slidably connected in the sliding hole along the radial direction of the fixed sleeve, and the first ends thereof being hinged to the piston rod of the air cylinder;

[0010] A plurality of claw assemblies, the plurality of claw assemblies corresponding to the plurality of link mechanisms one by one, each of the claw assemblies including a lifting rod and a clamping assembly, the lifting rod being fixed to the second end of the link mechanism, and the clamping assembly being fixed to the upper end of the lifting rod.

[0011] The beneficial effects that the utility model can achieve: The device can drive a plurality of link mechanisms to move through the air cylinder, drive a plurality of claw assemblies to move synchronously for clamping work, realize the self-centering function, and the link mechanism is slidably connected with the fixed sleeve through the sliding hole, improving the movement stability and bearing capacity of the link mechanism. The device can clamp workpieces with irregular outer surfaces, and can adjust the height of the clamping assembly through the lifting rod to adapt to the size of the workpiece, improving the clamping stability, avoiding wear of the clamping assembly, and avoiding affecting the machining accuracy.

[0012] Preferably, the link mechanism includes a slide bar and a connecting rod, the sliding hole includes a slide bar sliding hole and a connecting rod sliding hole which are arranged up and down and communicated, the length direction of the slide bar is arranged along the radial direction of the fixed sleeve and the first end thereof is slidably inserted into the slide bar sliding hole; the lifting rod is fixed to the top of the second end of the slide bar; the first end of the connecting rod is hinged to the piston rod of the air cylinder and the second end thereof passes through the connecting rod sliding hole and is hinged to the first end of the slide bar.

[0013] Preferably, a long-strip connecting rod movable groove is formed at the bottom of the slide bar and is arranged along the radial direction of the fixed sleeve, the second end of the connecting rod is hinged to the inner wall of the first end of the long-strip connecting rod movable groove, and the first end can abut against the bottom wall of the long-strip connecting rod movable groove to be received in the long-strip connecting rod movable groove.

[0014] Preferably, a rotating groove is formed at the bottom of the slide bar and is arranged along the length direction thereof, and the second end of the connecting rod is hinged in the rotating groove.

[0015] Preferably, the lifting rod includes a slide seat and a threaded rod, the slide seat is fixed to the top of the second end of the slide bar, the lower end of the threaded rod is threadedly connected to the top of the slide seat, and the clamping assembly is fixed to the upper end of the threaded rod.

[0016] Preferably, the clamping assembly includes a sliding sleeve, a first limiting block, and an elastic adjusting assembly. A first stop block is fixed to the top of the threaded rod. The sliding sleeve is slidably sleeved on the threaded rod below the first stop block and can abut against the inner side wall of the workpiece. The first limiting block is arranged perpendicular to the sliding sleeve, with one end fixed to the top of the sliding sleeve and the other end extending away from the center of the fixed sleeve. The elastic adjusting assembly is installed on the threaded rod between the sliding sleeve and the sliding seat.

[0017] Preferably, the elastic adjusting assembly includes a first tension spring and a first adjusting nut. The first tension spring is sleeved on the threaded rod below the sliding sleeve, and its top end is fixed to the sliding sleeve. The first adjusting nut is threadedly connected to the threaded rod corresponding to the lower part of the first tension spring and is fixedly connected to the bottom end of the first tension spring.

[0018] Preferably, it further includes a pressing assembly for assisting in pressing the workpiece. The pressing assembly includes a mounting frame, a lifting screw rod, and a floating pressing block. The mounting frame is fixed to the outer side wall of the fixed sleeve. The lifting screw rod is arranged along the axial direction of the fixed sleeve, and its lower end is threadedly connected to the mounting frame. The floating pressing block is installed at the top end of the lifting screw rod.

[0019] Preferably, the floating pressing block includes a second limiting block, a second tension spring, and a second adjusting nut. A second stop block is fixed to the top end of the lifting screw rod. The second limiting block is slidably sleeved on the lifting screw rod below the corresponding second stop block. The second tension spring is sleeved on the lifting screw rod below the second limiting block, and its top end is fixed to the second limiting block. The second adjusting nut is threadedly connected to the lifting screw rod below the second tension spring and is fixedly connected to the bottom end of the second tension spring.

[0020] Preferably, a positioning tray is further provided. The positioning tray is fixed to the top of the fixed sleeve and is provided with a central hole communicating with the inner cavity of the fixed sleeve. The top end of the sliding seat passes through the central hole and extends above the positioning tray. The bottom of the workpiece to be clamped is positioned and connected in the positioning tray.

[0021] As can be seen from the above technical solutions, compared with the prior art, the present utility model discloses an internal support type self-centering precision casting ball valve fixture. The air cylinder drives the connecting rod mechanism to drive the movement of the claw, realizing the internal support type self-centering clamping of the workpiece, with accurate positioning, convenient operation, large clamping force and high stability. The connecting rod mechanism is slidably connected to the fixed sleeve through a sliding hole, improving the stability and bearing capacity of the movement of the connecting rod mechanism. The positioning tray is used to position the bottom of the workpiece, facilitating the positioning of the workpiece. This device can clamp workpieces with irregular outer surfaces, and can adjust the height of the clamping component through the lifting rod to adapt to the size of the workpiece, improving the clamping stability, avoiding wear of the clamping component and affecting the machining accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present utility model. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on the provided drawings.

[0023] Figure 1 FIG. 1 is a schematic structural diagram of a working state of an internal support type self-centering precision casting ball valve fixture provided by the present utility model.

[0024] Figure 2 FIG. 2 is a three-dimensional structural diagram of an internal support type self-centering precision casting ball valve fixture provided by the present utility model.

[0025] Figure 3 FIG. 3 is a top view structural diagram of an internal support type self-centering precision casting ball valve fixture provided by the present utility model.

[0026] Figure 4 FIG. 4 is a sectional structural diagram of an internal support type self-centering precision casting ball valve fixture provided by the present utility model.

[0027] Figure 5 FIG. 5 is a three-dimensional structural diagram of a connecting rod mechanism and a claw assembly provided by the present utility model.

[0028] Figure 6 FIG. 6 is a three-dimensional structural diagram of a claw assembly provided by the present utility model.

[0029] Figure 7 FIG. 7 Figure 2 is an enlarged structural diagram of part A in FIG. 6.

[0030] In the figure: 1. Fixed sleeve, 11. Slide bar slide hole, 12. Connecting rod slide hole, 2. Cylinder, 21. Cylinder block, 22. Piston rod, 3. Link mechanism, 31. Slide bar, 311. Rotating groove, 32. Connecting rod, 4. Claw assembly, 41. Lifting rod, 411. Slide block, 412. Threaded rod, 42. Clamping assembly, 421. Slide sleeve, 422. First limit pressing block, 423. Elastic adjusting assembly, 4231. First tension spring, 4232. First adjusting nut, 5. Pressing assembly, 51. Mounting bracket, 52. Lifting screw rod, 53. Floating pressing block, 531. Second limit pressing block, 532. Second tension spring, 533. Second adjusting nut, 6. Positioning disc, 7. Workpiece. Detailed implementation mode

[0031] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0032] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0033] In the present invention, unless otherwise clearly defined and limited, the terms "installation", "connection", "connection", "fixation", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0034] Please refer to Figures 1-7 , the embodiment of the present invention discloses an inner support type self-centering precision casting ball valve fixture, including:

[0035] A fixed sleeve 1, and a plurality of slide holes are circumferentially and evenly spaced on the side wall of the fixed sleeve;

[0036] Cylinder 2; the cylinder block 21 of cylinder 2 is coaxially arranged with the fixed sleeve 1 and fixed at the bottom of the fixed sleeve 1. The bottom end of the piston rod 22 of cylinder 2 is slidably connected inside the cylinder block 21, and the top end extends into the inner cavity of the fixed sleeve 1;

[0037] A plurality of link mechanisms 3, the plurality of link mechanisms 3 correspond to the plurality of sliding holes one by one. Each link mechanism 3 is slidably connected in the sliding hole along the radial direction of the fixed sleeve 1, and its first end is hinged to the piston rod 22 of the cylinder 2;

[0038] A plurality of jaw assemblies 4, the plurality of jaw assemblies 4 correspond to the plurality of link mechanisms 3 one by one. Each jaw assembly 4 includes a lifting rod 41 and a clamping assembly 42. The lifting rod 41 is fixed to the second end of the link mechanism 3, and the clamping assembly 42 is fixed to the upper end of the lifting rod 41.

[0039] This device can drive a plurality of link mechanisms 3 to move through the cylinder 2, drive a plurality of jaw assemblies 4 to move synchronously for clamping work, realize the self-centering function. The link mechanism 3 is slidably connected to the fixed sleeve 1 through the sliding hole, improving the movement stability and bearing capacity of the link mechanism 3. This device can clamp the workpiece 7 with an irregular outer surface, and can adjust the height of the clamping assembly 42 through the lifting rod 41 to adapt to the size of the workpiece 7, improving the clamping stability, avoiding wear of the clamping assembly 42, and avoiding affecting the machining accuracy.

[0040] Specifically, the link mechanism 3 includes a slide bar 31 and a link 32. The sliding hole includes a slide bar sliding hole 11 and a link sliding hole 12 arranged up and down and communicating with each other. The length direction of the slide bar 31 is arranged along the radial direction of the fixed sleeve 1, and its first end is slidably inserted into the slide bar sliding hole 11; the lifting rod 41 is fixed to the top of the second end of the slide bar 31; the first end of the link 32 is hinged to the piston rod 22 of the cylinder 2, and its second end passes through the link sliding hole 12 and is hinged to the first end of the slide bar 31. Through the cooperation of the slide bar 31 and the slide bar sliding hole 11, the bearing capacity of the link 32 is reduced, avoiding damage to the link 32 due to excessive pressure.

[0041] More specifically, two sliders are symmetrically formed on the inner side wall of the slide bar sliding hole 11, both of which are arranged along its axial direction. Sliding grooves are formed on the side wall of the slide bar 31 and are slidably matched with the two sliders respectively, improving the stability of the slide bar 31 during the sliding process.

[0042] Specifically, a rotating groove 311 is formed at the bottom of the slide bar 31 along its length direction. The second end of the link 32 is rotatably connected to the inner side walls of the two sides of the rotating groove 311 through a rotating shaft.

[0043] Specifically, the lifting rod 41 includes a sliding seat 411 and a threaded rod 412. The sliding seat 411 is fixed to the top of the second end of the sliding bar 31. The lower end of the threaded rod 412 is threadedly connected to the top of the sliding seat 411, and the clamping assembly 42 is fixed to the upper end of the threaded rod 412. The threaded connection between the sliding seat 411 and the threaded rod 412 is convenient for adjustment and has high stability.

[0044] Specifically, the clamping assembly 42 includes a sliding sleeve 421, a first limiting pressing block 422, and an elastic adjusting assembly 423. A first stop block is fixed to the top end of the threaded rod 412. The sliding sleeve 421 is slidably sleeved on the threaded rod 412 below the first stop block and can abut against the inner side wall of the workpiece. The first limiting pressing block 422 is arranged perpendicular to the sliding sleeve 421, with one end fixed to the top of the sliding sleeve 421 and the other end extending away from the center of the fixed sleeve 1. The elastic adjusting assembly 423 is installed on the threaded rod 412 between the sliding sleeve 421 and the sliding seat 411.

[0045] More specifically, the elastic adjusting assembly 423 includes a first tension spring 4231 and a first adjusting nut 4232. The first tension spring 4231 is sleeved on the threaded rod 412 below the sliding sleeve 421, and its top end is fixed to the sliding sleeve 421. The first adjusting nut 4232 is threadedly connected to the threaded rod 412 corresponding to the lower part of the first tension spring 4231 and is fixedly connected to the bottom end of the first tension spring 4231. When adjusting the height of the threaded rod 412 so that the first limiting pressing block 422 contacts the top wall of the workpiece 7, it is impossible to accurately control the pressing force of the first limiting pressing block 422. Therefore, during the adjustment process, the first limiting pressing block 422 or the workpiece 7 may be damaged due to excessive pressing force. The elastic adjusting assembly 423 is provided to enable the first limiting pressing block 422 to automatically adjust the pressing force under the elastic action of the spring, preventing damage to the workpiece 7 or the clamping assembly 42 caused by improper adjustment.

[0046] Specifically, it further includes a pressing assembly 5 for assisting in pressing the workpiece 7. The pressing assembly 5 includes a mounting frame 51, a lifting screw 52, and a floating pressing block 53. The mounting frame 51 is fixed to the outer side wall of the fixed sleeve 1. The lifting screw 52 is arranged along the axial direction of the fixed sleeve 1, and its lower end is threadedly connected to the mounting frame 51. The floating pressing block 53 is installed at the top end of the lifting screw 52. It further limits the workpiece 7 to prevent the workpiece 7 from moving and improves the machining accuracy.

[0047] More specifically, the floating pressing block 53 includes a second limiting pressing block 531, a second tension spring 532, and a second adjusting nut 533. A second stop block is fixed to the top end of the lifting screw rod 52. The second limiting pressing block 531 is slidably sleeved on the lifting screw rod 52 below the corresponding second stop block. The second tension spring 532 is sleeved on the lifting screw rod 52 below the second limiting pressing block 531, and its top end is fixed to the second limiting pressing block 531. The second adjusting nut 533 is threadedly connected to the lifting screw rod 52 below the second tension spring 532 and is fixed to the bottom end of the second tension spring 532. This enables the second limiting pressing block 531 to automatically adjust the pressing force under the elastic action of the second tension spring 532, preventing the pressing force from being too small to firmly clamp or too large to damage the workpiece 7 or the pressing assembly 5.

[0048] Specifically, a positioning tray 6 is further provided. The positioning tray 6 includes a bottom plate and side plates. A central hole communicating with the inner cavity of the fixed sleeve 1 is opened in the middle of the bottom plate. The top end of the sliding seat 411 passes through the central hole and extends above the bottom plate. The bottom wall of the valve body abuts against the bottom plate, and the lower flange surface abuts against the inner side wall of the side plate, so that it is positioned and connected in the positioning tray 6. The positioning tray 6 is provided with a positioning notch, and the riser at the lower end of the valve body is clamped in the positioning notch, which can not only achieve the precise positioning of the valve body, but also prevent the valve body from rotating to a certain extent.

[0049] Working principle:

[0050] When the investment casting ball valve blank is transported above the fixture, the riser at its lower end is placed corresponding to the positioning notch of the positioning tray in the positioning tray. The operator opens the air valve to allow air to enter the rodless cavity of the cylinder 2. When a certain pressure is reached, it pushes the piston rod to move linearly, drives the three claw assemblies 4 to move simultaneously through the connecting rod 32 and the slide bar 31, makes the three claw assemblies 4 approach the investment casting ball valve blank simultaneously, and internally supports the investment casting ball valve blank. Adjust the position of the clamping assembly according to the workpiece specifications to ensure that the workpiece can be internally supported and clamped. When the clamping force reaches the predetermined value, keep the air pressure in the air cylinder stable to ensure that the workpiece 7 is firmly clamped. After the claw assembly 4 completes stable internal support and clamping, adjust the pressing assembly 5 to the appropriate position to complete the clamping of the workpiece 7.

[0051] In this specification, each embodiment is described in a progressive manner. The key point of each embodiment is to illustrate the differences from other embodiments. The same or similar parts among the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the description of the method part.

[0052] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present utility model. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present utility model. Therefore, the present utility model will not be limited to these embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An internally supported self-centering precision casting ball valve fixture, characterized in that, Comprising: A fixed sleeve (1), on the side wall of which a plurality of sliding holes are circumferentially and evenly spaced; A cylinder (2); the cylinder block (21) of the cylinder (2) is coaxially arranged with the fixed sleeve (1) and fixed at the bottom of the fixed sleeve (1), and the bottom end of the piston rod (22) of the cylinder (2) is slidably connected in the cylinder block (21), and the top end extends into the inner cavity of the fixed sleeve (1); A plurality of link mechanisms (3), the plurality of link mechanisms (3) corresponding one by one to the plurality of sliding holes, each link mechanism (3) being slidably connected in the sliding hole along the radial direction of the fixed sleeve (1), and the first end of each being hinged to the piston rod (22) of the cylinder (2); A plurality of claw assemblies (4), the plurality of claw assemblies (4) corresponding one by one to the plurality of link mechanisms (3), each claw assembly (4) including a lifting rod (41) and a clamping assembly (42), the lifting rod (41) being fixed to the second end of the link mechanism (3), and the clamping assembly (42) being fixed to the upper end of the lifting rod (41).

2. The internal support type self-centering precision casting ball valve fixture according to claim 1, characterized in that, The link mechanism (3) includes a slide bar (31) and a connecting rod (32), the sliding hole includes a slide bar sliding hole (11) and a connecting rod sliding hole (12) arranged up and down and communicating with each other, the length direction of the slide bar (31) is arranged along the radial direction of the fixed sleeve (1), and the first end thereof is slidably inserted into the slide bar sliding hole (11); the lifting rod (41) is fixed to the top of the second end of the slide bar (31); the first end of the connecting rod (32) is hinged to the piston rod (22) of the cylinder (2), and the second end thereof passes through the connecting rod sliding hole (12) and is hinged to the first end of the slide bar (31).

3. The internal support type self-centering precision casting ball valve fixture according to claim 2, characterized in that, On the inner side wall of the slide bar sliding hole (11), two sliders are symmetrically formed and are both arranged along its axial direction, and on the side wall of the slide bar (31), chutes are provided which are slidably engaged with the two sliders respectively.

4. The internal support type self-centering precision casting ball valve fixture according to claim 2, wherein On the bottom of the slide bar (31), a rotating groove (311) is provided along its length direction, and the second end of the connecting rod (32) is hinged in the rotating groove (311).

5. The internal support type self-centering precision casting ball valve fixture according to claim 2, characterized in that, The lifting rod (41) includes a sliding seat (411) and a threaded rod (412), the sliding seat (411) is fixed to the top of the second end of the slide bar (31), the lower end of the threaded rod (412) is threadedly connected to the top of the sliding seat (411), and the clamping assembly (42) is fixed to the upper end of the threaded rod (412).

6. The internal support type self-centering precision casting ball valve fixture according to claim 5, characterized in that, The clamping assembly (42) includes a sliding sleeve (421), a first limiting pressing block (422) and an elastic adjusting assembly (423), a first stop block is fixed to the top end of the threaded rod (412), the sliding sleeve (421) is slidably sleeved on the threaded rod (412) below the first stop block and can abut against the inner side wall of the workpiece, the first limiting pressing block (422) is arranged perpendicular to the sliding sleeve (421), one end of which is fixed to the top of the sliding sleeve (421), and the other end extends in a direction away from the center of the fixed sleeve (1); the elastic adjusting assembly (423) is installed on the threaded rod (412) between the sliding sleeve (421) and the sliding seat (411).

7. The internal support type self-centering precision casting ball valve fixture according to claim 6, characterized in that, The elastic adjustment component (423) includes a first tension spring (4231) and a first adjusting nut (4232). The first tension spring (4231) is sleeved on the threaded rod (412) below the sliding sleeve (421), and its top end is fixed to the sliding sleeve (421); the first adjusting nut (4232) is threadedly connected to the threaded rod (412) corresponding to the lower part of the first tension spring (4231) and is fixedly connected to the bottom end of the first tension spring (4231).

8. The inner support type self-centering precision casting ball valve fixture according to claim 7, characterized in that It further includes a pressing component (5) for assisting in pressing the workpiece. The pressing component (5) includes a mounting frame (51), a lifting screw rod (52), and a floating pressing block (53). The mounting frame (51) is fixed on the outer side wall of the fixed sleeve (1). The lifting screw rod (52) is arranged along the axial direction of the fixed sleeve (1), and its lower end is threadedly connected to the mounting frame (51). The floating pressing block (53) is installed at the top end of the lifting screw rod (52).

9. The internal support type self-centering precision casting ball valve fixture according to claim 8, characterized in that, The floating pressing block (53) includes a second limiting pressing block (531), a second tension spring (532), and a second adjusting nut (533). A second stop block is fixed at the top end of the lifting screw rod (52). The second limiting pressing block (531) is slidably sleeved on the lifting screw rod (52) corresponding to the lower part of the second stop block. The second tension spring (532) is sleeved on the lifting screw rod (52) below the second limiting pressing block (531), and its top end is fixed to the second limiting pressing block (531). The second adjusting nut (533) is threadedly connected to the lifting screw rod (52) below the second tension spring (532) and is fixed to the bottom end of the second tension spring (532).

10. A kind of inner support type self-centering precision casting ball valve fixture according to claim 5, characterized in that, A positioning tray (6) is further provided. The positioning tray (6) is fixed on the top of the fixed sleeve (1), and a central hole communicating with the inner cavity of the fixed sleeve (1) is opened thereon. The top end of the sliding seat (411) passes through the central hole and extends above the positioning tray (6); the bottom of the workpiece (7) to be clamped is positioned and connected in the positioning tray (6).

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