A compact pneumatic switching mechanism

Abstract

The utility model relates to punch die switching mechanism technical field, concretely relates to a compact pneumatic switching mechanism, it includes by upper to lower setting in proper order cylinder, cylinder connecting plate, base, drive block, sliding block, reset structure, the cylinder is installed on the base, drive block is located below the base, and drive block reciprocates along horizontal direction under the action of cylinder and cylinder connecting plate, reset structure sets up on the sliding block, sliding block and drive block sliding connection, and sliding block reciprocates along vertical direction under the action of drive block and reset structure. The utility model is especially suitable for the die environment of compact horizontal space, has the advantages of compact horizontal space structure, reset reliable and convenient installation. Space utilization is high, and sliding block reset reliability is strong, and stability is high, and compact structure installation is convenient. The utility model can solve how to realize the efficient layout of pneumatic switching mechanism in limited space, and satisfy the technical problem of structural stability and compactness requirement.

Description

Technical Field

[0001] This utility model belongs to the technical field of stamping die switching mechanism, specifically relating to a compact pneumatic switching mechanism. Background Technology

[0002] Pneumatic switching mechanisms are widely used in stamping dies. A traditional pneumatic switching mechanism typically includes a fixed base, a slider, a drive block, and a cylinder. The slider is movably arranged above the drive block, and the cylinder is arranged laterally on the side of the drive block. Due to the structural characteristics of the products formed, fender stamping dies have very strict requirements for lateral space, and ordinary pneumatic switching mechanisms cannot meet these requirements.

[0003] The pneumatic switching mechanism of existing fender stamping dies typically has the following problems:

[0004] 1) Large space occupation: Because the cylinder of the pneumatic switching mechanism is arranged laterally on the side of the drive block, it occupies a lot of space laterally, making it difficult to meet the installation requirements of stamping dies with compact lateral space.

[0005] 2) Low reliability of slider reset: The slider reset structure, such as nitrogen spring, lacks a forced reset design and is prone to slider reset failure due to inertia or friction.

[0006] 3) Insufficient slider stability: The slider's return stroke relies on a single spring, which can easily lead to jamming or falling.

[0007] 4) Loose structure: The design of the fixing base is redundant and the connecting parts are scattered, resulting in a bulky overall size.

[0008] Because the existing pneumatic switching mechanism uses a horizontally placed cylinder, the horizontal space is large, the overall volume is bulky, and the mold space utilization rate is low. In addition, the slider reset structure relies on the reset spring, which is prone to fatigue failure after long-term use, resulting in low reliability and insufficient stability of slider reset. Utility Model Content

[0009] The purpose of this invention is to provide a compact pneumatic switching mechanism that can solve the technical problems of how to achieve an efficient layout of the pneumatic switching mechanism in a limited space, as well as the low reliability and insufficient stability of the slider reset.

[0010] To achieve the above objectives, this utility model provides the following technical solution:

[0011] This utility model discloses a compact pneumatic switching mechanism, comprising, from top to bottom, a cylinder, a cylinder connecting plate, a base, a drive block, a slider, and a reset structure. The cylinder is mounted on the base, and the drive block is located below the base. A stroke hole is formed on the base, through which the cylinder connecting plate passes. One end of the cylinder connecting plate is connected to the side of the cylinder, and the other end is connected to the side of the drive block. The drive block reciprocates horizontally under the action of the cylinder and the cylinder connecting plate. The reset structure is disposed on the slider. The slider is slidably connected to the drive block, and the slider reciprocates vertically under the action of the drive block and the reset structure.

[0012] As a preferred embodiment, the reset structure is a reset nitrogen spring and / or a buckling mechanism. The reset nitrogen spring is disposed vertically inside the slider, the bottom of the buckling mechanism is mounted vertically on the slider, and the top of the buckling mechanism extends upward into the drive block.

[0013] As a preferred embodiment, the undercut mechanism includes an undercut block and a linkage device. The undercut block includes an undercut part, a mounting part, and a connecting part. The undercut part is located inside the drive block, the mounting part is disposed on the slider, the connecting part is used to connect the undercut part and the mounting part, and the linkage device is connected to the undercut part.

[0014] As a preferred embodiment, the slider includes an upper slider and a lower slider connected to each other. The upper slider is slidably connected to the drive block, and the lower slider is located below the upper slider. The upper end of the upper slider is provided with a sliding part that cooperates with the drive block. The left side of the upper slider is provided with a movable groove, and the connecting part of the undercut block is located in the movable groove. The upper end of the lower slider is provided with a mounting groove, and a nitrogen gas groove is provided inside. The mounting part of the undercut block is set in the mounting groove, and the reset nitrogen spring is set in the nitrogen gas groove.

[0015] As a preferred embodiment, the drive block includes a body, a drive part, and a limiting part. The left side of the body is provided with a clearance groove corresponding to the movable groove. The limiting part is located at the end of the clearance groove. The undercut part of the undercut block is located in the clearance groove and cooperates with the limiting part. The drive part is located below the body and cooperates with the sliding part.

[0016] As a preferred embodiment, the pneumatic switching mechanism further includes a fixed base, which is installed below the base. The fixed base has a hollow structure inside, and the drive block, slider, and reset structure are all disposed inside the cavity. The bottom of the fixed base has an opening, and when the slider is lifted, the end of the slider extends through the opening to the outside of the fixed base.

[0017] Furthermore, the mounting base has a notch on its right side, forming an inverted L-shape, with the horizontal edge of the L-shape installed below the base. This saves space, improves space utilization, and avoids interference with the fender.

[0018] Furthermore, the top front and rear sides of the fixing base are provided with stepped structures to form stepped bosses, and screw holes and locating pin holes are provided on the stepped bosses. This allows for quick and precise connection with the fender mold.

[0019] The beneficial effects of this utility model are:

[0020] This invention provides a compact pneumatic switching mechanism, which is particularly suitable for mold environments with compact lateral space. It has the advantages of compact lateral space structure, reliable resetting and convenient installation.

[0021] (1) High space utilization: The cylinder is installed longitudinally and combined with the L-shaped fixed seat, which reduces the overall lateral volume by more than 30%;

[0022] (2) High reliability of slider reset: The forced reset mechanism avoids the fatigue problem of traditional springs, and the reset success rate reaches 100%;

[0023] (3) High slider stability: The built-in reset nitrogen spring provides double protection to prevent the slider from falling off and assist the slider return stroke;

[0024] (4) Compact structure and easy installation: The outer frame step design simplifies the positioning of screws and pins, and reduces the installation time by 50%.

[0025] Therefore, this invention can solve the technical problem of how to achieve an efficient layout of a pneumatic switching mechanism within a limited space, while meeting the requirements of structural stability and compactness. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the main structure of the pneumatic switching mechanism;

[0027] Figure 2 This is a schematic cross-sectional view of the slider in the lifting state;

[0028] Figure 3 This is a schematic diagram of the slider's retracted state.

[0029] Figure 4 This is a partial three-dimensional schematic diagram of the pneumatic switching mechanism;

[0030] Figure 5 This is a schematic diagram of a partial explosion of the pneumatic switching mechanism;

[0031] Figure 6 A three-dimensional schematic diagram of the mounting base;

[0032] Figure 7 This is a schematic diagram of the pneumatic switching mechanism installed in the mold.

[0033] Explanation of reference numerals in the attached figures:

[0034] Cylinder assembly: 1-Cylinder; 12-Cylinder connecting plate; 13-Cylinder connecting rod;

[0035] Base structure: 30-base, 31-stroke hole;

[0036] Fixed base structure: 2-fixed base, 21-opening, 22-notch, 23-step structure;

[0037] Sliding structure: 5-lower slider (51-mounting groove, 52-nitrogen tank); 9-upper slider (91-moving groove, 92-sliding part);

[0038] Drive structure: 10-Drive block, 11-Body, 15-Drive part, 13-Limiting part, 14-Allowing groove;

[0039] Reset structure: 3-Inverted mechanism; 4-Reset nitrogen spring;

[0040] Inverted locking mechanism: 6-Inverted locking block (61-Inverted locking part, 62-Mounting part, 63-Connecting part);

[0041] 7-Screw hole; 8-Positioning pin hole; 20-L Angle iron; 100-Switching mechanism; 200-Fender. Detailed Implementation

[0042] To make the technical problem solved by this utility model, the technical solution adopted, and the technical effect achieved clearer, the technical solution of this utility model will be further described below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only for explaining this utility model and not for limiting it. Furthermore, it should be noted that, for ease of description, only the parts related to this utility model are shown in the accompanying drawings, not all of them.

[0043] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this utility model and for 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. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Specifically, the terms "first position" and "second position" refer to two different positions.

[0044] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections or detachable connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal connections between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0045] This utility model belongs to the field of mechanical design technology, specifically relating to a compact pneumatic switching mechanism, particularly suitable for mold environments with limited lateral space. Addressing the problems in the background art, this utility model aims to provide a solution with a compact lateral space structure, reliable resetting, and convenient installation, as detailed below:

[0046] 1) By optimizing the cylinder layout and mounting structure, the lateral space occupied by the switching mechanism is significantly reduced;

[0047] 2) A forced reset design is adopted to ensure the reliability of the reset action of the buckling mechanism;

[0048] 3) The slider integrates a reset nitrogen spring and a borrow space design to improve slider stability;

[0049] 4) The fixed base has an outer frame stepped structure on the side to simplify the mold connection process and reduce the space volume.

[0050] This utility model provides a compact pneumatic switching mechanism, comprising, from top to bottom, a cylinder 1, a fixed base 2, a cylinder connecting plate 12, a base 30, a drive block 10, a slider, and a reset structure; the cylinder 1 is mounted on the base 30, and the drive block 10 is located below the base 30; the base 30 has a stroke hole 31, the cylinder connecting plate 12 passes through the stroke hole 31, one end is connected to the side of the cylinder 1, and the other end is connected to the side of the drive block 10, the drive block 10 reciprocates horizontally under the action of the cylinder 1 and the cylinder connecting plate 12; the reset structure is disposed on the slider; the slider is slidably connected to the drive block 10, and the slider reciprocates vertically under the action of the drive block 10 and the reset structure.

[0051] The reset structure is a reset nitrogen spring 4 and / or a buckling mechanism 3. The reset nitrogen spring 4 is arranged vertically inside the slider. The bottom of the buckling mechanism 3 is mounted vertically on the slider, and the top of the buckling mechanism 3 extends upward into the drive block 10.

[0052] The undercut mechanism 3 includes an undercut block 6 and a linkage device. The undercut block 6 includes an undercut part 61, a mounting part 62, and a connecting part 63. The undercut part 61 is located inside the drive block 10. The mounting part 62 is disposed on the slider. The connecting part 63 is used to connect the undercut part 61 and the mounting part 62. The linkage device is connected to the undercut part 61.

[0053] The slider includes an upper slider 9 and a lower slider 5 connected to each other. The upper slider 9 is slidably connected to the driving block 10, and the lower slider 5 is located below the upper slider 9. The upper end of the upper slider 9 is provided with a sliding part 92 that cooperates with the driving block 10. The left side of the upper slider 9 is provided with a movable groove 91, and the connecting part 63 of the undercut block 6 is located in the movable groove 91. The upper end of the lower slider 5 is provided with a mounting groove 51, and a nitrogen groove 52 is provided inside. The mounting part 62 of the undercut block 6 is set in the mounting groove 51, and the reset nitrogen spring 4 is set in the nitrogen groove 52.

[0054] The drive block 10 includes a body 11, a drive part 15, and a limiting part 13. The left side of the body 11 is provided with a relief groove 14 corresponding to the movable groove 91. The limiting part 13 is located at the end of the relief groove 14. The undercut part 61 of the undercut block 6 is located in the relief groove 14 and cooperates with the limiting part 13. The drive part 15 is located below the body 11 and cooperates with the sliding part 92.

[0055] The fixing seat 2 is installed below the base 30. The fixing seat 2 has a hollow structure inside, and the drive block 10, slider, and reset structure are all housed within the cavity. The bottom of the fixing seat 2 has an opening 21, through which the end of the slider extends to the outside of the fixing seat 2 when the slider is lifted. The right side of the fixing seat 2 has a notch 22, forming an inverted L-shape, with the horizontal edge of the L-shape installed below the base 30. This saves space and improves space utilization; it also avoids interference with the fender. The top front and rear sides of the fixing seat 2 have stepped structures 23, forming stepped bosses with screw holes and locating pin holes. This allows for quick and precise connection with the mold.

[0056] The technical solution of this utility model will be further described below with reference to the accompanying drawings and specific embodiments.

[0057] like Figures 1 to 3 As shown, the pneumatic switching mechanism includes the following core components: cylinder, L-shaped fixed seat, inverted mechanism, reset nitrogen spring, upper slider, lower slider, drive block, L-angle iron, cylinder connecting plate, cylinder connecting rod, and pad.

[0058] Cylinder assembly: The cylinder assembly includes a cylinder 1, a cylinder connecting plate 12, and a cylinder connecting rod 13. One end of the cylinder connecting rod 13 is connected to the cylinder 1, and the other end is connected to the cylinder connecting plate 12. The cylinder connecting plate 12 is arranged vertically, and its upper end is connected to the drive block 10.

[0059] Longitudinal cylinder mounting: The cylinder is vertically mounted on the top of the base, with the cylinder, drive block, and slider in the same direction, reducing the space occupied by the switching mechanism in the length direction. Generally, in switching mechanisms, the cylinder and drive seat are in the same direction, while the slider is arranged perpendicularly to the drive seat, thus the switching mechanism occupies a large space in the length direction. The cylinder 1 is fixed to the top of the L-shaped fixed base 2 using two L-shaped angle irons 20 and bolted together to ensure horizontal movement. Alternatively, the cylinder 1 can be mounted on the side of the L-shaped fixed base 2 in the width direction, adjusting its position according to the mold space.

[0060] like Figure 6 As shown, the fixing seat adopts an L-shaped integrated structure, reducing the lateral space requirement while enhancing overall rigidity. The outer frame edge of the fixing seat has stepped bosses for screw holes and locating pin holes, enabling quick and precise connection with the mold. The L-shaped fixing seat 2 is integrally formed from high-strength steel, with an internal hollow structure. Its short side connects to the cylinder 1, and its long side is fixed to the mold outer frame via pins.

[0061] Internal layout of the L-shaped fixing seat: The lower slider 5 and the upper slider 9 are installed in the internal cavity of the L-shaped fixing seat 2. The lower slider 5 and the upper slider 9 are connected by screws, and the two sliders are guided through the internal cavity of the L-shaped fixing seat 2. In addition, the drive block 10 can reciprocate horizontally within the internal cavity of the L-shaped fixing seat 2. The drive block 10 is connected to the cylinder through the cylinder connecting plate 12 and the cylinder connecting rod 13, thereby transmitting the power provided by the cylinder. The lower slider 5 and the upper slider 9 are connected by screws to form a whole. The undercut mechanism 3 is fixed to the lower slider 5 by screws. The undercut mechanism 3 has clearance fit with the upper slider 9 and the drive block 10 respectively, and the upper slider 9 has sliding fit with the drive block 10.

[0062] Screw holes 7 and locating pin holes 8 are provided on the outer frame steps of the fixed seat. During installation, the stepped surface fits against the mold surface to ensure connection accuracy and further reduce the space occupied by the switching mechanism in the mold. Because the fender part is C-shaped, the process of adding a charging port opening in the mold needs to avoid the reinforcing ribs of the pressure core, and the space requirements are very strict. Figure 7 This switching mechanism can avoid the fender pressure core, has a more compact structure, and can ensure the normal operation of the switching function without damaging the pressure core structure and the strength of the mold, thereby meeting the purpose of realizing the overall function of the mold and achieving maximum application value.

[0063] A reset nitrogen spring is installed inside the slider: the reset nitrogen spring 4 is embedded inside the lower slider 5, using the groove on the side wall of the lower slider 5 as a buffer space. One end of the reset nitrogen spring 4 is connected to the lower slider 5, and the other end is fixed to the L-shaped fixing seat 2 to provide reset force. The reset nitrogen spring is installed inside the slider using its own buffer space as a nitrogen buffer device, which not only assists its return stroke but also prevents the slider from falling.

[0064] like Figure 4 , 5 As shown, the reverse mechanism is a forced reset mechanism: The reverse mechanism includes a reverse block and a mechanical linkage device (such as a cam or lever). The reverse block achieves the forced reset of the slider through the mechanical linkage device, which can also prevent the slider from falling during the reset process, avoid excessive reliance on nitrogen spring reset, and improve the service life and stability of the pneumatic switching mechanism.

[0065] The lower slider 5 and the upper slider 9 are connected by screws to form a whole. The forced reset buckle mechanism 3 is fixed to the lower slider 5 by screws. During the return stroke, the slider as a whole is linked with the cylinder piston rod through the forced reset buckle mechanism 3. When the cylinder 1 extends, it pushes the buckle to unlock. When it retracts, it is forced to reset through the cam inclined surface, thus completing the action of the forced reset mechanism.

[0066] Slider lifting process:

[0067] Cylinder 1 retracts to the left, causing cylinder connecting rod 13 to move to the left, which in turn causes cylinder connecting plate 12 and drive block 10 to move to the left. Drive block 10 and upper slider 9 are connected by inclined sliding engagement. Under normal circumstances, upper slider 9 and lower slider 5 move downward together under the push of inverted mechanism 3 and reset nitrogen spring 4 until the bottom plane of drive block 10 contacts the top plane of upper slider 9. Drive block 10 then holds upper slider 9 to stop its downward movement. At the same time, inverted mechanism 3 and lower slider 5 also stop their downward movement. If reset nitrogen spring 4 fails and cannot push upper slider 9 and lower slider 5 downward, the inverted block will continue to drive upper slider 9 and lower slider 5 downward under the action of linkage device (such as cam or lever) to complete the lifting action until the bottom plane of drive block 10 contacts the top plane of upper slider 9. Drive block 10 then holds upper slider 9 and lower slider 5 to stop their downward movement, thus achieving the purpose of inverted mechanism 3 forcibly lifting the slider. After that, the drive block 10 continues to move to the left to its limit position under the action of the cylinder 1. At this time, the bottom plane of the drive block 10 is completely aligned with the top plane of the upper slider 9, and the slider lifting process is completed.

[0068] Slider retraction process:

[0069] Cylinder 1 extends to the right, causing cylinder connecting rod 13 to move to the right, which in turn causes cylinder connecting plate 12 and drive block 10 to move to the right until the inclined surface of drive block 10 just contacts the inclined surface of upper slider 9, at which point the thrust of drive block 10 on upper slider 9 disappears. Under normal circumstances, the upper slider 9 and the lower slider 5 move upward under the action of the inverted mechanism 3 and the reset nitrogen spring 4. At this time, if the reset nitrogen spring 4 fails and cannot push the upper slider 9 and the lower slider 5 to move upward, the inverted block will unlock under the action of the linkage device (such as a cam or lever) and continue to drive the upper slider 9 and the lower slider 5 to move upward so that they retract, thereby achieving the purpose of the inverted mechanism 3 forcibly driving the slider to retract. The inverted part on the inverted block cooperates with the limiting part at the end of the drive block 10 to play a limiting role, restricting the drive block 10 from moving to the right alone during this process, thereby ensuring that the drive block 10 moves to the right and the upper slider 9 and the lower slider 5 move upward synchronously, until the drive block 10 continues to move to the right to the limit position and the upper slider 9 and the lower slider 5 move to the limit position of upward movement, at which point the slider retraction process is completed.

[0070] In this invention, the inverted mechanism 3 and the reset nitrogen spring 4 both serve to lift and reset the slider. They can be used individually or together, providing dual protection.

[0071] This utility model has the following advantages compared to the prior art:

[0072] (1) High space utilization: The cylinder is installed longitudinally and combined with the L-shaped fixed seat, which reduces the overall volume by more than 30%;

[0073] (2) High reliability of reset: The forced reset mechanism avoids the fatigue problem of traditional springs, and the reset success rate reaches 100%;

[0074] (3) Improved slider stability: The built-in reset nitrogen spring provides double protection to prevent the lower slider from falling off and assist in the return stroke;

[0075] (4) Easy installation: The outer frame step design simplifies the positioning of screws and pins, reducing installation time by 50%.

[0076] The embodiments described above are merely illustrative of several implementations of this utility model, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of this utility model patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this utility model, and these all fall within the protection scope of this utility model. Therefore, the protection scope of this utility model patent should be determined by the appended claims.

Claims

1. A compact pneumatic switching mechanism, characterized in that: The system includes, from top to bottom, a cylinder (1), a cylinder connecting plate (12), a base (30), a drive block (10), a slider, and a reset structure. The cylinder (1) is mounted on the base (30), and the drive block (10) is located below the base (30). A stroke hole (31) is provided on the base (30), and the cylinder connecting plate (12) passes through the stroke hole (31), with one end connected to the side of the cylinder (1) and the other end connected to the side of the drive block (10). The drive block (10) reciprocates horizontally under the action of the cylinder (1) and the cylinder connecting plate (12). The reset structure is provided on the slider. The slider is slidably connected to the drive block (10), and the slider reciprocates vertically under the action of the drive block (10) and the reset structure.

2. The compact pneumatic switching mechanism according to claim 1, characterized in that: The reset structure is a reset nitrogen spring (4) and / or a buckling mechanism (3). The reset nitrogen spring (4) is arranged vertically inside the slider. The bottom of the buckling mechanism (3) is installed vertically on the slider. The top of the buckling mechanism (3) extends upward into the drive block (10).

3. A compact pneumatic switching mechanism according to claim 2, characterized in that: The undercut mechanism (3) includes an undercut block (6) and a linkage device. The undercut block (6) includes an undercut part (61), an mounting part (62), and a connecting part (63). The undercut part (61) is located inside the drive block (10). The mounting part (62) is mounted on the slider. The connecting part (63) is used to connect the undercut part (61) and the mounting part (62). The linkage device is connected to the undercut part (61).

4. A compact pneumatic switching mechanism according to claim 3, characterized in that: The slider includes an upper slider (9) and a lower slider (5) connected to each other. The upper slider (9) is slidably connected to the drive block (10), and the lower slider (5) is located below the upper slider (9). The upper end of the upper slider (9) is provided with a sliding part (92) that cooperates with the drive block (10). The left side of the upper slider (9) is provided with a movable groove (91), and the connecting part (63) of the undercut block (6) is located in the movable groove (91). The upper end of the lower slider (5) is provided with an installation groove (51), and a nitrogen groove (52) is provided inside. The installation part (62) of the undercut block (6) is set in the installation groove (51), and the reset nitrogen spring (4) is set in the nitrogen groove (52).

5. A compact pneumatic switching mechanism according to claim 4, characterized in that: The drive block (10) includes a body (11), a drive part (15), and a limiting part (13). The left side of the body (11) is provided with a clearance groove (14) corresponding to the movable groove (91). The limiting part (13) is located at the end of the clearance groove (14). The undercut part (61) of the undercut block (6) is located in the clearance groove (14) and cooperates with the limiting part (13). The drive part (15) is located below the body (11) and cooperates with the sliding part (92).

6. A compact pneumatic switching mechanism according to any one of claims 1 to 5, characterized in that: The pneumatic switching mechanism also includes a fixed seat (2), which is installed below the base (30). The fixed seat (2) has a cavity structure inside, and the drive block, slider, and reset structure are all set inside the cavity. The bottom of the fixed seat (2) has an opening (21), and when the slider is lifted, the end of the slider extends through the opening (21) to the outside of the fixed seat (2).

7. A compact pneumatic switching mechanism according to claim 6, characterized in that: The fixing seat (2) has a notch (22) on the right side, forming an inverted L shape, with the horizontal side of the L shape installed below the base (30).

8. A compact pneumatic switching mechanism according to claim 7, characterized in that: The fixed base (2) has a stepped structure (23) on the front and rear sides of the top, forming a stepped boss. Screw holes and positioning pin holes are opened on the stepped boss.

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