Modularized metal precise guide plate

Abstract

The invention discloses a modularized precise metal guide plate, and relates to the technical field of osteotomy guide plates, the modularized precise metal guide plate comprises a fixed guide module and a corresponding test module, the fixed guide module is fixed on a bone through a fixed seat, the corresponding test module is connected with the fixed guide module through an extension rod, and after a vertical kirschner wire is driven through a semicircular hole, the test module is connected with the fixed guide module; adjusting a connecting plate according to a size mark, then moving a simulation block, moving an arc frame along with the simulation block, freely releasing a sliding rod in the moving process, after the lower end of the sliding rod corresponds to an indication frame, pressing a pressing rod, taking down a corresponding test module, locking the arc frame through a sliding hole block, and driving a kirschner wire with a corresponding angle into an angle hole; and then the fixed guide module is taken down, and the swing saw cutting work is completed according to the guidance of the kirschner wire.

Description

Technical Field

[0001] This invention relates to the field of osteotomy guide technology, specifically to a modular metal precision guide. Background Technology

[0002] In the field of foot and ankle deformity correction, such as flat feet, high arches, or hallux valgus, wedge osteotomy is the main technique for correcting bony deformities such as calcaneal varus, medial wedge tilt, or first metatarsal rotation, restoring the normal biomechanical structure of the foot. Wedge osteotomy relies on the precision of the osteotomy angle during surgery; an accurate angle ensures proper deformity correction. However, current surgical methods primarily depend on the surgeon's preoperative planning and intraoperative experience. In practice, surgeons often remove a portion of bone based on experience, then adjust the procedure according to the post-operative appearance: insufficient bone removal requires further osteotomy, while excessive removal necessitates adjustments. Repeated procedures prolong the operation time, potentially affecting osteotomy precision and impacting deformity correction and functional recovery. To improve precision, personalized 3D-printed osteotomy guides are currently designed based on preoperative CT data. These guides enable highly precise individualized osteotomy, but their high cost hinders DIP / DRG medical insurance cost control.

[0003] In summary, the current wedge osteotomy procedure has the following technical problems: Because different patients have different bone sizes, at the same angle, in order to ensure that the intersection of the angle osteotomy surface and the vertical osteotomy surface is located on the distal surface of the bone, the distance between the starting point of the angle osteotomy and the vertical osteotomy surface increases with the increase of bone size. Therefore, the fixed angle osteotomy guide plate is not suitable for the different bone thicknesses of patients, which will cause the intersection of the angle osteotomy surface and the vertical osteotomy surface to fail to penetrate the bone, resulting in the inability to cut the bone block, or cutting too much bone block far below the bone. Summary of the Invention

[0004] In view of the above-mentioned problems in the existing technology, the present invention provides a modular metal precision guide plate.

[0005] To achieve the above-mentioned technical objectives and effects, the present invention is implemented through the following technical solution:

[0006] A modular metal precision guide plate includes a fixed guiding module and a corresponding testing module. The fixed guiding module includes a frame assembly, a central positioning assembly, and a moving assembly. The central positioning assembly is mounted on the frame assembly, and the moving assemblies are located on both sides of the central positioning assembly. The moving assemblies are slidably connected to the frame assembly. The corresponding testing module includes a measuring assembly and a corresponding assembly. An extension rod connects the measuring assembly and the central positioning assembly. The corresponding assembly is slidably connected to the measuring assembly, and an extension rod connects the corresponding assembly and the moving assembly.

[0007] Furthermore, the frame assembly includes side frames and upper rods. Two side frames are provided, and fixed seats are fixedly connected to the front and rear sides of the two side frames. Two upper rods are fixedly connected to the upper side of one side frame. A lower groove is provided between the side frame and the upper rods. A middle groove is provided between the two upper rods on one side frame. A rotating groove is opened at one end of the side frame near the middle groove. A pressure rod is provided at the middle groove. A rotating frame is fixedly connected to the end of the pressure rod away from the rotating groove. A rotating shaft is fixedly connected in the middle of the rotating frame. The rotating shaft is rotatably connected to the upper rod. A rotating seat is provided at the end of the pressure rod away from the rotating frame. A vertical shaft is fixedly connected to the lower side of the rotating seat. The vertical shaft is rotatably connected to the pressure rod. A rotating plate is fixedly connected to the rotating seat.

[0008] The lower side of the pressure plate has several slots.

[0009] Furthermore, the center positioning component includes a fixing hole block, and the fixing hole block is provided in the middle of the lower groove. The fixing hole block is fixedly connected to the side frame and the upper rod.

[0010] The extension rod connected to the measuring component is slidably connected in the middle of the fixed hole block.

[0011] Furthermore, the moving component includes an arc frame and sliding hole blocks. The arc frame has a plurality of angle holes arrayed on it. The angle holes point radially toward the center of the slide along the circle of the arc frame. There are two slides, which are symmetrically arranged. The two slides have semi-circular holes at close range, and the two semi-circular holes form a hole equivalent to the angle holes. Sliding hole blocks are fixedly connected to both sides of the arc frame. The sliding hole blocks are slidably connected in the lower groove. A locking block is fixedly connected to the sliding hole block at the position corresponding to the middle groove. The locking block engages with the locking groove.

[0012] The extension rod connected to the corresponding component is slidably connected in the middle of the sliding hole block.

[0013] Furthermore, the sliding hole block has a square structure, and the shape of the sliding hole block corresponds to the lower groove; this prevents the sliding hole block from rotating within the lower groove.

[0014] Furthermore, the measuring component includes a measuring column and a sliding frame. A transverse groove is opened in the middle of the upper side of the measuring column. Fixing blocks are fixedly connected to both sides of one end of the measuring column at the transverse groove. A square hole is opened at the connection position between the measuring column and the fixing block. The extension rod connected to the fixing block is slidably connected in the square hole.

[0015] The measuring column has a vertical groove on one side of the other end of the horizontal groove. A sliding frame is slidably connected to the measuring column at the position of the vertical groove. A slider is fixedly connected to the sliding frame. The slider is slidably connected in the vertical groove. Connecting plates are fixedly connected to both sides of the sliding frame. The connecting plates are slidably connected to both sides of the measuring column. The measuring column has dimension markings on the corresponding side of the connecting plate. An indicator frame is connected to the connecting plate on one side of the fixed block of the measuring column. The indicator frame is matched with the corresponding component.

[0016] Furthermore, a friction strip is fixedly connected inside the vertical groove, and the friction strip abuts against the slider; this makes it necessary for the user to exert force to move the slider inside the vertical groove, and the position stabilizes after the force is removed.

[0017] Furthermore, the corresponding component includes a simulation block, which corresponds to the arc frame. The simulation block has corresponding holes that correspond to the angle holes. A sliding plate is fixedly connected to the simulation block. The sliding plate is slidably connected in the transverse groove. Side holes are opened on both sides of the simulation block. The extension rod connected to the sliding hole block is slidably connected in the side holes.

[0018] Furthermore, the corresponding component also includes a slide cylinder, which is slidably connected to the corresponding hole. The slide cylinder has a sliding hole in the middle. A limit ring is fixedly connected to the upper end of the slide cylinder. The limit ring cooperates with the simulation block. A slide rod is slidably connected in the sliding hole. The lower end of the slide rod abuts against the measuring column. The lower end of the slide rod cooperates with the indicator frame. A sliding plate is fixedly connected to the upper end of the slide rod. The slide plate is slidably connected in the sliding hole. The sliding hole is a stepped hole that cooperates with the slide plate and the slide rod. An air hole is opened on the slide plate.

[0019] The beneficial effects of this invention are:

[0020] A modular metal precision guide plate first fixes the fixed guide module to the skeleton via a fixing base. The corresponding test module and the fixed guide module are connected by an extension rod. After inserting a vertical Kirschner wire through a semi-circular hole, the bone thickness is obtained. The reference size mark of the connecting plate is adjusted, and then the simulation block is moved. At the same time, the arc frame moves with it. During the movement, the slide bar is released freely. After the lower end of the slide bar aligns with the indicator frame, the pressure bar is pressed and the corresponding test module is removed. The arc frame is locked through the sliding hole block. Kirschner wires of the corresponding angle are inserted through the angle hole. Then the fixed guide module is removed, and the oscillating saw cutting work is completed according to the guidance of the Kirschner wires.

[0021] Of course, any product implementing this invention does not necessarily need to achieve all of the advantages described above at the same time. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the overall structure of the modular metal precision guide plate described in an embodiment of the present invention;

[0024] Figure 2 This is a schematic diagram of the structural connection between the side frame and the arc frame according to an embodiment of the present invention;

[0025] Figure 3 This is a schematic diagram of the side frame and fixing hole block according to an embodiment of the present invention;

[0026] Figure 4 This is a schematic diagram of the upper rod structure according to an embodiment of the present invention;

[0027] Figure 5 This is a schematic diagram of the upper rod and the pressure rod according to an embodiment of the present invention;

[0028] Figure 6 This is a schematic diagram of the structure of the pressure bar, rotating frame, and rotating shaft according to an embodiment of the present invention;

[0029] Figure 7 This is a schematic diagram of the slot structure of the pressure rod according to an embodiment of the present invention;

[0030] Figure 8 This is a schematic diagram of the structure of the pressure rod and the rotating seat according to an embodiment of the present invention;

[0031] Figure 9 This is a schematic diagram of the structure of the rotary base, vertical shaft, and rotating plate according to an embodiment of the present invention;

[0032] Figure 10 This is a schematic diagram of the structure of the arc frame and sliding hole block according to an embodiment of the present invention;

[0033] Figure 11 This is a schematic diagram of the structure of the arc frame, sliding hole block, and locking block according to an embodiment of the present invention;

[0034] Figure 12 This is a schematic diagram of the structure of the measuring column, sliding frame, simulation block, and sliding cylinder described in an embodiment of the present invention;

[0035] Figure 13 This is a schematic diagram of the measuring column and fixing block according to an embodiment of the present invention;

[0036] Figure 14 This is a schematic cross-sectional view of the measuring column described in an embodiment of the present invention;

[0037] Figure 15 This is a schematic diagram of the structure of the sliding frame and slider according to an embodiment of the present invention;

[0038] Figure 16 This is a schematic diagram of the structure of the simulation block and the sliding plate described in an embodiment of the present invention;

[0039] Figure 17 This is a schematic diagram of the other side of the measuring column, sliding frame, simulation block, and sliding cylinder described in an embodiment of the present invention;

[0040] Figure 18 This is a schematic diagram of the structure of the slide cylinder and slide rod according to an embodiment of the present invention;

[0041] Figure 19 This is a schematic diagram of the structure of the slide cylinder and the limiting ring according to an embodiment of the present invention;

[0042] Figure 20 This is a schematic diagram of the structure of the slide bar and slide plate according to an embodiment of the present invention;

[0043] Figure 21 This is a schematic diagram of the extension rod described in an embodiment of the present invention;

[0044] Figure 22 This is a schematic diagram of the second structure of the side frame according to an embodiment of the present invention;

[0045] Figure 23 This is a schematic diagram of the third structure of the side frame according to an embodiment of the present invention;

[0046] Figure 24 This is a schematic diagram of the fourth structure of the side frame according to an embodiment of the present invention;

[0047] Figure 25 This is a cross-sectional schematic diagram of the fourth structure of the side frame described in an embodiment of the present invention.

[0048] The attached diagram lists the components represented by each number as follows:

[0049] 1-Side frame, 101-Fixed base, 102-Upper rod, 103-Lower groove, 104-Middle groove, 105-Rotating groove, 106-Pressure rod, 107-Card slot, 108-Rotating frame, 109-Rotating shaft, 110-Rotating base, 111-Vertical shaft, 112-Rotating plate, 113-Fixed hole block, 120-Arc frame, 121-Angle hole, 122-Sliding hole block, 123-Card block, 124-Semicircular hole, 2-Extension rod, 3-Measuring column, 3 00-Horizontal groove, 301-Fixing block, 302-Side hole, 303-Dimension mark, 304-Vertical groove, 305-Friction strip, 310-Sliding frame, 311-Slider, 312-Connecting plate, 313-Indicator frame, 320-Simulation block, 321-Slide plate, 322-Corresponding hole, 323-Side hole, 330-Sliding cylinder, 331-Sliding hole, 332-Limiting ring, 333-Sliding rod, 334-Sliding plate, 335-Air hole. Detailed Implementation

[0050] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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 are within the scope of protection of the present invention.

[0051] Example 1

[0052] like Figure 1-25 As shown

[0053] The present invention discloses a modular metal precision guide plate, comprising a fixed guiding module and a corresponding testing module. The fixed guiding module includes a frame assembly, a central positioning assembly, and a moving assembly. The frame assembly is provided with the central positioning assembly, and the moving assemblies are provided on both sides of the central positioning assembly. The moving assemblies are slidably connected to the frame assembly. The corresponding testing module includes a measuring assembly and a corresponding assembly. An extension rod (2) is connected between the measuring assembly and the central positioning assembly. The corresponding assembly is slidably connected to the measuring assembly, and an extension rod (2) is connected between the corresponding assembly and the moving assembly.

[0054] The frame assembly includes side frames (1) and upper rods (102). Two side frames (1) are provided, with fixed seats (101) fixedly connected to the front and rear sides of each side frame (1). Two upper rods (102) are fixedly connected to the upper side of each side frame (1). A lower groove (103) is provided between the side frame (1) and the upper rods (102). A middle groove (104) is provided between the two upper rods (102) on one side frame (1). A rotating groove (105) is opened at one end of the side frame (1) near the middle groove (104). A pressure rod (106) is provided at the position of the middle groove (104). The pressure rod (106) is fixedly connected to a rotating frame (108) at the end away from the rotating groove (105). A rotating shaft (109) is fixedly connected in the middle of the rotating frame (108). The rotating shaft (109) is rotatably connected to the upper rod (102). A rotating seat (110) is provided at the end of the pressure rod (106) away from the rotating frame (108). A vertical shaft (111) is fixedly connected to the lower side of the rotating seat (110). The vertical shaft (111) is rotatably connected to the pressure rod (106). A rotating plate (112) is fixedly connected to the rotating seat (110). Several slots (107) are arranged on the lower side of the pressure plate.

[0055] The center positioning component includes a fixing hole block (113), and the fixing hole block (113) is provided in the middle of the lower groove (103). The fixing hole block (113) is fixedly connected to the side frame (1) and the upper rod (102). The extension rod (2) connected to the measuring component is slidably connected in the middle of the fixing hole block (113).

[0056] Example 2

[0057] like Figure 10-11 As shown

[0058] The moving component includes an arc frame (120) and a sliding hole block (122). The arc frame (120) has a plurality of angle holes (121) arranged in an array. The angle holes (121) point radially toward the center of the slide along the circle of the arc frame (120). There are two slides, which are symmetrically arranged. The two slides have semi-circular holes (124) at close range. The two semi-circular holes (124) form a hole equivalent to the angle holes (121). The sliding hole blocks (122) are fixedly connected to both sides of the arc frame (120). The sliding hole blocks (122) are slidably connected in the lower groove (103). The sliding hole blocks (122) are fixedly connected to the corresponding positions of the sliding hole blocks (122) and the middle groove (104). The locking blocks (123) are engaged with the locking groove (107). The extension rod (2) connected to the corresponding component is slidably connected in the middle of the sliding hole block (122).

[0059] The sliding hole block (122) has a square structure, and the shape of the sliding hole block (122) corresponds to the lower groove (103); to prevent the sliding hole block (122) from rotating in the lower groove (103);

[0060] Example 3

[0061] like Figure 12-21 As shown

[0062] The measuring assembly includes a measuring column (3) and a sliding frame (310). A horizontal groove (300) is formed in the middle of the upper side of the measuring column (3). Fixing blocks (301) are fixedly connected to both sides of one end of the horizontal groove (300). A square hole (302) is formed at the connection point between the measuring column (3) and the fixing blocks (301). An extension rod (2) connected to the fixing block (113) is slidably connected within the square hole (302). A vertical groove (304) is formed on one side of the other end of the horizontal groove (300). The measuring column (3) is positioned at the vertical groove (304). A sliding frame (310) is slidably connected, and a slider (311) is fixedly connected to the sliding frame (310). The slider (311) is slidably connected in the vertical groove (304). A connecting plate (312) is fixedly connected to both sides of the sliding frame (310). The connecting plate (312) is slidably connected to both sides of the measuring column (3). The measuring column (3) has a dimension mark on the corresponding side of the connecting plate (312). An indicator frame (313) is connected to the fixing block (301) side of the measuring column (3) on the connecting plate (312). The indicator frame (313) is correspondingly matched with the corresponding component.

[0063] A friction strip (305) is fixedly connected inside the vertical groove (304), and the friction strip (305) abuts against the slider (311); so that the slider (311) needs to be controlled by the user to move in the vertical groove (304), and the position is stable after the force is removed after the movement.

[0064] The corresponding component includes a simulation block (320), which corresponds to the arc frame (120). The simulation block (320) has a corresponding hole (322) that corresponds to the angle hole (121). A sliding plate (321) is fixedly connected to the simulation block (320). The sliding plate (321) is slidably connected in the transverse groove (300). Side holes (323) are opened on both sides of the simulation block (320). The extension rod (2) connected to the sliding hole block (122) is slidably connected in the side hole (323).

[0065] The corresponding component also includes a slide cylinder (330), which is slidably connected in the corresponding hole (322). The slide cylinder (330) has a sliding hole (331) in the middle. A limit ring (332) is fixedly connected to the upper end of the slide cylinder. The limit ring (332) cooperates with the simulation block (320). A slide rod (333) is slidably connected in the sliding hole (331). The lower end of the slide rod (333) abuts against the measuring column (3). The lower end of the slide rod (333) cooperates with the indicator frame (313). A sliding plate (334) is fixedly connected to the upper end of the slide rod (333). The slide plate (321) is slidably connected in the sliding hole (331). The sliding hole (331) is a stepped hole that cooperates with the slide plate (321) and the slide rod (333). An air hole (335) is opened on the slide plate (321).

[0066] Example 4

[0067] like Figure 22-25 As shown

[0068] The side frame (1) is designed in different styles.

[0069] In summary, the present invention provides a modular metal precision guide plate. First, the fixed guide module is fixed to the bone through the fixed base (101). The corresponding test module and the fixed guide module are connected through the extension rod (2). After the vertical Kirschner wire is driven through the semi-circular hole (124), the bone thickness is obtained. The connecting plate (312) is adjusted according to the reference size mark (303). Then, the simulation block (320) is moved, and the arc frame (120) moves along with it. During the movement, the slide rod (333) is released freely. After the lower end of the slide rod (333) corresponds to the indicator frame (313), the pressure rod (106) is pressed. The corresponding test module is removed. The arc frame (120) is locked through the sliding hole block (122). Kirschner wires of the corresponding angle are driven through the angle hole (121). Then, the fixed guide module is removed. The oscillating saw cutting work is completed according to the Kirschner wire guidance, achieving infinitely adjustable precision cutting.

[0070] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0071] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A modular metal precision guide plate, characterized in that: The system includes a fixed guidance module and a corresponding testing module. The fixed guidance module includes a frame assembly, a central positioning assembly, and a moving assembly. The frame assembly has a central positioning assembly, and the moving assemblies are located on both sides of the central positioning assembly. The moving assemblies are slidably connected to the frame assembly. The corresponding testing module includes a measurement assembly and a corresponding assembly. An extension rod connects the measurement assembly and the central positioning assembly. The corresponding assembly is slidably connected to the measurement assembly, and an extension rod connects the corresponding assembly and the moving assembly.

2. The modular metal precision guide plate as described in claim 1, characterized in that: The frame assembly includes side frames and upper rods. There are two side frames, and fixed seats are fixedly connected to the front and rear sides of the two side frames. Two upper rods are fixedly connected to the upper side of one side frame. A lower groove is provided between the side frame and the upper rods. A middle groove is provided between the two upper rods on one side frame. A rotating groove is opened at one end of the side frame near the middle groove. A pressure rod is provided at the middle groove. A rotating frame is fixedly connected to the end of the pressure rod away from the rotating groove. A rotating shaft is fixedly connected in the middle of the rotating frame. The rotating shaft is rotatably connected to the upper rod. A rotating seat is provided at the end of the pressure rod away from the rotating frame. A vertical shaft is fixedly connected to the lower side of the rotating seat. The vertical shaft is rotatably connected to the pressure rod. A rotating plate is fixedly connected to the rotating seat. The lower side of the pressure plate has several slots.

3. The modular metal precision guide plate as described in claim 2, characterized in that: The central positioning component includes a fixing hole block, and the fixing hole block is provided in the middle of the lower groove. The fixing hole block is fixedly connected to the side frame and the upper rod. The extension rod connected to the measuring component is slidably connected in the middle of the fixed hole block.

4. The modular metal precision guide plate as described in claim 3, characterized in that: The moving component includes an arc frame and sliding hole blocks. The arc frame has a plurality of angle holes arranged in an array. The angle holes point radially toward the center of the slide along the circle of the arc frame. There are two slides, which are symmetrically arranged. The two slides have semi-circular holes at close range, and the two semi-circular holes form a hole equivalent to the angle holes. Sliding hole blocks are fixedly connected to both sides of the arc frame. The sliding hole blocks are slidably connected in the lower groove. A locking block is fixedly connected to the sliding hole block at the position corresponding to the middle groove. The locking block engages with the locking groove. The extension rod connected to the corresponding component is slidably connected in the middle of the sliding hole block.

5. The modular metal precision guide plate as described in claim 4, characterized in that: The sliding hole block has a square structure, and its shape corresponds to the lower groove; this prevents the sliding hole block from rotating within the lower groove.

6. The modular metal precision guide plate as described in claim 5, characterized in that: The measuring assembly includes a measuring column and a sliding frame. A horizontal groove is opened in the middle of the upper side of the measuring column. Fixing blocks are fixedly connected to both sides of one end of the measuring column. A square hole is opened at the connection position between the measuring column and the fixing block. The extension rod connected to the fixing block is slidably connected in the square hole. The measuring column has a vertical groove on one side of the other end of the horizontal groove. A sliding frame is slidably connected to the measuring column at the position of the vertical groove. A slider is fixedly connected to the sliding frame. The slider is slidably connected in the vertical groove. Connecting plates are fixedly connected to both sides of the sliding frame. The connecting plates are slidably connected to both sides of the measuring column. The measuring column has dimension markings on the corresponding side of the connecting plate. An indicator frame is connected to the connecting plate on one side of the fixed block of the measuring column. The indicator frame is matched with the corresponding component.

7. The modular metal precision guide plate as described in claim 6, characterized in that: A friction strip is fixedly connected inside the vertical groove, and the friction strip abuts against the slider; this makes it necessary for the user to exert force to move the slider in the vertical groove, and the position is stable after the force is removed.

8. The modular metal precision guide plate as described in claim 7, characterized in that: The corresponding component includes a simulation block, which corresponds to the arc frame. The simulation block has corresponding holes that correspond to the angle holes. A sliding plate is fixedly connected to the simulation block. The sliding plate is slidably connected in the transverse groove. Side holes are opened on both sides of the simulation block. The extension rod connected to the sliding hole block is slidably connected in the side holes.

9. The modular metal precision guide plate as described in claim 8, characterized in that: The corresponding component also includes a slide cylinder, which is slidably connected to the corresponding hole. The slide cylinder has a sliding hole in the middle. A limit ring is fixedly connected to the upper end of the slide cylinder. The limit ring cooperates with the simulation block. A slide rod is slidably connected in the sliding hole. The lower end of the slide rod abuts against the measuring column. The lower end of the slide rod cooperates with the indicator frame. A slide plate is fixedly connected to the upper end of the slide rod. The slide plate is slidably connected in the sliding hole. The sliding hole is a stepped hole that cooperates with the slide plate and the slide rod. An air hole is opened on the slide plate.

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