Center positioning rod of hole opener with stable positioning and easy maintenance and hole opening cutter head using the same

Abstract

The utility model provides a center positioning rod of a hole opener with stable positioning and easy maintenance, which is an elastic compressible and reset spring telescopic rod. The center positioning rod of the hole opener includes a bottom rod, a middle rod, a top rod and a compression spring; the middle rod is provided with a second hollow cavity for embedding the compression spring, and the two ends of the compression spring elastically press the bottom rod and the top rod respectively; the bottom rod and the middle rod are coaxially detachably connected, and the bottom rod and the middle rod slide against each other when the bottom end of the bottom of the bottom rod is compressed; the middle rod is coaxially and detachably threaded with the top rod of the jack; the bottom end structure of the bottom of the bottom rod is bullet-shaped or inverted cone-shaped or hemispherical. The utility model also provides a hole opening tool head, including the center positioning rod of the hole opener, a main drill bit and a tool handle as described above, the bottom surface of the bottom of the tool handle is provided with a blind hole, and the top of the top rod can be plugged into the blind hole. The utility model improves the stability of the center positioning and hole opening of the hole opening tool head and is convenient for maintenance.

Description

Technical Field

[0001] The utility model relates to the technical field of hole openers, in particular to a center positioning rod of a hole opener which is stable in positioning and easy to maintain and a hole opening cutter head using the same. Background Art

[0002] A hole opener is used to open holes in walls or other hard panels. The hole opener generally includes a drilling rig and a hole opening cutter head installed on the rotating head of the drilling rig. The main drill bit of the hole opening cutter head is generally cylindrical, and the wall-breaking end of the main drill bit of the hole opening cutter head is generally provided with diamond drill teeth. The main drill bit of the hole opening cutter head utilizes the principle of diamond cutting and breaking rocks to drill holes. During the drilling operation, inaccurate positioning is often encountered. The reason is that the contact area between the main drill bit of the hole opening cutter head and the drilling surface is large, and the main drill bit of the hole opening cutter head is difficult to drill in quickly. During the long drilling positioning process, the main drill bit of the hole opening cutter head will deviate from the predetermined position due to vibration, resulting in poor accuracy of the drilling position. Therefore, the Chinese utility model patent with patent application number 201721731602.X discloses a diamond drill bit that can improve the accuracy of drilling position, the diamond drill bit includes a diamond main drill bit, a centering drill bit and a drill shank, after the centering drill bit is inserted into the square blind hole at the head end of the drill shank, the centering drill bit needs to be fixed by bolts, and the centering drill bit is provided with a cutting thread, and the centering drill bit protrudes from the end face of the diamond main drill bit for cutting the wall. During positioning, the centering drill bit is driven by the square blind hole and drills the hole forcefully through the cutting thread on the centering drill bit, the cutting thread of the centering drill bit will wear out after long-term use, so the centering drill bit needs to be replaced; in addition, the centering drill bit will still produce certain vibrations when cutting and drilling under force, so it cannot meet the requirements of more stable and accurate hole opening. Utility Model Content

[0003] In view of this, it is necessary to propose a center positioning rod of a hole opener with stable positioning and easy maintenance and a hole opening cutter head using the same to overcome several shortcomings of the above-mentioned background technology and solve the following technical problems:

[0004] How to improve the center positioning of the hole opening cutter head and the stability of the hole opening and facilitate the maintenance of the center positioning rod of the hole opener.

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

[0006] The utility model provides a center positioning rod of a hole opener with stable positioning and easy maintenance. One end of the center positioning rod of the hole opener can be detachably installed in the center mounting hole of a hole opening cutter head as an accessory of the hole opener. The other end of the center positioning rod of the hole opener is used for pressing and positioning on an object to be opened. The center positioning rod of the hole opener is a spring telescopic rod that can be elastically compressed and reset. The center positioning rod of the hole opener comprises a bottom rod, a middle rod, a top rod and a compression spring. The middle rod is provided with a second hollow cavity for embedding the compression spring. The compression spring is inserted into the middle cavity. The two ends of the spring elastically press the bottom rod and the top rod respectively; the bottom rod is coaxially detachably connected to the middle rod, and the bottom rod and the middle rod slide displaced with each other when the bottom end of the bottom of the bottom rod is pressed; the middle rod is coaxially and detachably threadedly connected to the jack top rod; the top of the top rod is used to be detachably installed in the central mounting hole of the hole opening tool head of the hole opener; the bottom end structure of the bottom of the bottom rod is used to position and press against the object to be opened; the bottom end structure of the bottom of the bottom rod is bullet-shaped, inverted cone-shaped or hemispherical.

[0007] Furthermore, the structure of the bottom rod is in the shape of a nail with a nail cap, and the bottom rod includes a nail cap portion and a nail column portion; the bottom end surface and the top end surface of the middle rod are respectively provided with a nail through hole and a spring threaded hole, and the nail through hole and the spring threaded hole both penetrate into the second hollow cavity; the outer diameter of the nail cap portion of the bottom rod is larger than the inner hole diameter of the nail through hole, and the diameter of the nail column portion of the bottom rod is smaller than the inner hole diameter of the nail through hole, and the nail column portion of the bottom rod extends into the nail through hole; the spring threaded hole is provided with an internal thread, and the bottom end portion of the top rod is provided with an external thread, and the portion of the bottom end portion of the top rod provided with the external thread is screwed and installed with the spring threaded hole provided with the internal thread.

[0008] Furthermore, a circular shaft limiting annular platform is protruded from the middle of the push rod, and the circular shaft limiting annular platform surrounds the virtual central axis of the push rod; the circular shaft limiting annular platform is used to limit the direction in which the push rod extends into the central mounting hole.

[0009] The utility model further provides a hole-drilling cutter head using a center positioning rod of a hole-drilling device with stable positioning and easy maintenance as described in any of the above items, as an accessory of the hole-drilling device, used for drilling holes in cooperation with a drilling machine of the hole-drilling device, characterized in that the hole-drilling cutter head comprises the center positioning rod of the hole-drilling device, a main drill bit and a shank, the main drill bit is a cylindrical drill bit structure provided with a first hollow cavity, and a drill opening for drilling a hole is provided on the bottom surface of the bottom of the main drill bit; the shank serves as an intermediate connecting piece between the drilling machine and the main drill bit, the top of the shank is used for installation on the rotating part of the drilling machine, a blind hole is provided on the bottom surface of the bottom of the shank, and the top of the top rod extends into the first hollow cavity of the main drill bit and can be inserted into the blind hole in a pluggable manner; the blind hole is located at the center of the bottom surface of the bottom of the shank;

[0010] When the central positioning rod of the hole opener does not press the object to be opened, the bottom end of the bottom of the bottom rod protrudes from the drilling end surface of the main drill bit.

[0011] Furthermore, the blind hole has a circular opening, the top of the push rod is cylindrical, and an elastic damping member is provided between the blind hole and the top of the push rod.

[0012] Furthermore, the elastic damping member is an elastic rubber ring; a plurality of mounting grooves are arranged around the top of the top rod member; each mounting groove is sleeved with an elastic rubber ring; the outer ring diameter of the elastic rubber ring when installed in the mounting groove is larger than the diameter of the blind hole, so that when the top of the center positioning rod of the hole opener is inserted into the blind hole, the elastic rubber ring is squeezed by the inner wall surface of the blind hole and the bottom surface of the corresponding mounting groove.

[0013] Furthermore, the tool handle is provided with a vent hole, which passes through the inner wall of the blind hole; when the top of the center positioning rod of the hole opener is inserted into the blind hole, the air in the blind hole is squeezed and discharged through the vent hole, and when the top of the center positioning rod of the hole opener is pulled outward in the blind hole, the outside air enters the blind hole through the vent hole.

[0014] Furthermore, a circular shaft limiting annular platform is protruding from the middle of the push rod component, which surrounds the virtual center axis of the push rod component, and the outer diameter of the circular shaft limiting annular platform is larger than the inner diameter of the blind hole; the circular shaft limiting annular platform is used to limit the direction in which the push rod component extends into the blind hole.

[0015] The beneficial effects of the utility model are:

[0016] When the hole opener performs positioning pre-drilling through the hole opening cutter head equipped with the above-mentioned hole opener center positioning rod, the bottom rod is pressed against the wall through the bottom end of the bottom of the bottom rod by the compression spring, so that the wall is pressed against and rotated by the bottom end of the bottom of the bottom rod, so that a pit for center positioning is left on the wall, and at the same time, the main drill bit performs accurate and stable pre-grooving on the wall, and the center positioning rod of the hole opener performs center drilling in the wall or other hard plate body and performs accurate and stable pre-grooving through the cylindrical main drill bit; when the main drill bit is close to the wall, the bottom end of the bottom of the bottom rod that previously protruded from the bottom surface of the main drill bit elastically shrinks, so that the center positioning rod of the hole opener obtains the pit for center positioning, and will not affect the accurate positioning of the pre-grooving corresponding to the main drill bit due to excessive center positioning drilling and drilling vibration, and will not make the center positioning rod of the hole opener easily damaged; the three-stage combined installation method of the center positioning rod of the hole opener is convenient for replacing accessories and storage, and can make the center positioning rod of the hole opener act as a spring telescopic rod to achieve elastic compressible reset. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of a half-section structure of the center positioning rod of the hole opener with stable positioning and easy maintenance in the front view of the utility model;

[0018] Figure 2It is a partial structural schematic diagram of the front view of the installation groove of the center positioning rod of the hole opener with stable positioning and easy maintenance of the utility model;

[0019] Figure 3 It is a schematic diagram of the installation structure of the elastic rubber ring involved in the utility model in the front view direction;

[0020] Figure 4 It is a structural schematic diagram of the bottom rod member involved in the utility model in a front view;

[0021] Figure 5 It is a half-section structural schematic diagram of the middle rod member involved in the utility model in the front view direction;

[0022] Figure 6 It is a half-section structural schematic diagram of the top rod member involved in the utility model in the front view direction;

[0023] Figure 7 It is a half-section structural schematic diagram of the hole-opening cutter head of the utility model in the front view direction;

[0024] Figure 8 It is a schematic diagram of a half-section structure of the main drill bit involved in the utility model in the front view direction;

[0025] Fig. 9 It is a schematic diagram of a half-section structure of a main drill bit involved in the utility model in a top view;

[0026] Fig.10 It is a schematic diagram of a half-section structure of the main drill bit involved in the utility model when viewed from the bottom;

[0027] Fig.11 It is a structural schematic diagram of the knife handle involved in the utility model in a front view;

[0028] Fig.12 This is a schematic diagram of the structure of the knife handle involved in the utility model when viewed from above;

[0029] Description of reference numerals:

[0030] Main drill bit 1; tool handle 2; hole opener center positioning rod 3; elastic rubber ring 4; blind hole 21; mounting groove 31; bottom rod 32; middle rod 33; top rod 34; compression spring 35; outer ring diameter R1 of elastic rubber ring 4 mounted in mounting groove 31; nail cap part 321; nail column part 322; nail through hole 331; spring threaded hole 332; circular shaft limiting annular platform 36; first hollow cavity 11; second hollow cavity 333; mounting threaded hole 12. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solution and advantages of the utility model clearer, the technical solution of the utility model will be further clearly and completely described below in combination with the embodiments of the utility model. It should be noted that the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the utility model.

[0032] It should be understood that the directions or positional relationships indicated by terms such as "upper", "lower", "front", "back", "left", and "right" are based on the directions or positional relationships shown in the accompanying drawings and are only for the convenience of describing the present invention and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they should not be understood as limitations on the present invention.

[0033] The terms "first", "second", "third", "fourth", etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the definition of "first", "second", "third", "fourth" features may explicitly or implicitly include one or more of the features.

[0034] Example 1

[0035] like Figure 1-6 As shown:

[0036] The present embodiment provides a center positioning rod of a hole opener with stable positioning and easy maintenance. One end of the center positioning rod 3 of the hole opener is detachably mounted in the center mounting hole of the hole opening cutter head as an accessory of the hole opener. The other end of the center positioning rod 3 of the hole opener is used to press and position on the object to be opened (such as a wall or a plate). The center positioning rod 3 of the hole opener is an elastically compressible and resetting spring telescopic rod. The center positioning rod 3 of the hole opener includes a bottom rod 32, a middle rod 33, a top rod 34 and a compression spring 35. The middle rod 33 is provided with a second hollow cavity 333 for embedding the compression spring 35. The two ends of the compression spring 35 elastically press the bottom rod 32 and the top rod 34 respectively; the bottom rod 32 is coaxially detachably connected with the middle rod 33, and the bottom rod 32 and the middle rod 33 slide displaced with each other when the bottom end of the bottom of the bottom rod 32 is pressed; the middle rod 33 is coaxially and detachably threadedly connected with the jack top rod 34; the top of the top rod 34 is used for detachably mounting in the central mounting hole of the hole opening cutter head of the hole opener; the bottom end structure of the bottom of the bottom rod 32 is used for positioning and pressing against the object to be opened; the bottom end structure of the bottom of the bottom rod 32 is bullet-shaped, inverted cone-shaped or hemispherical.

[0037] Optimally, the structure of the bottom rod 32 is in the shape of a nail with a nail cap, and the bottom rod 32 includes a nail cap portion 321 and a nail column portion 322; the bottom end surface and the top end surface of the middle rod 33 are respectively provided with a nail through hole 331 and a spring threaded hole 332, and the nail through hole 331 and the spring threaded hole 332 both penetrate into the second hollow cavity 333; the outer diameter of the nail cap portion 321 of the bottom rod 32 is larger than the inner hole diameter of the nail through hole 331, and the diameter of the nail column portion 322 of the bottom rod 32 is smaller than the inner hole diameter of the nail through hole 331, and the nail column portion 322 of the bottom rod 32 extends into the nail through hole 331; the spring threaded hole 332 is provided with an internal thread, and the bottom end portion of the top rod 34 is provided with an external thread, and the portion of the bottom end portion of the top rod 34 provided with the external thread is screwed and installed with the spring threaded hole 332 provided with the internal thread.

[0038] Optimally, a circular shaft limiting annular platform 36 is protruded from the middle of the push rod 34, and the circular shaft limiting annular platform 36 surrounds the virtual central axis of the push rod 34; the circular shaft limiting annular platform 36 is used to limit the direction in which the push rod 34 extends into the central mounting hole.

[0039] Example 2

[0040] Embodiment 2 is an optimized design of any technical solution in Embodiment 1;

[0041] like Figure 1-Figure 12 As shown:

[0042] The present embodiment proposes a hole punching cutter head using a center positioning rod of a hole opener with stable positioning and easy maintenance as described in any technical solution of Embodiment 1, as an accessory of the hole opener, used to cooperate with the drilling rig of the hole opener to drill holes, the hole punching cutter head comprises the center positioning rod 3 of the hole opener, a main drill bit 1 and a shank 2, the main drill bit 1 is a cylindrical drill bit structure provided with a first hollow cavity 11, and a drill hole for drilling holes is provided on the bottom surface of the bottom of the main drill bit 1; the shank 2 serves as an intermediate connecting piece between the drilling rig and the main drill bit 1, the top of the shank 2 is used to be installed on the rotating part of the drilling rig, and a blind hole 21 is provided on the bottom surface of the bottom of the shank 2, and the top of the push rod 34 extends into the first hollow cavity 11 of the main drill bit 1 and can be plugged into the blind hole 21; the blind hole 21 is located at the center of the bottom surface of the bottom of the shank 2;

[0043] When the hole opener center positioning rod 3 is not pressing against the object to be drilled, the bottom end of the bottom of the bottom rod 32 protrudes from the drilling end surface of the main drill bit 1, that is, protrudes from the bottom surface of the main drill bit 1.

[0044] Optimally, the blind hole 21 has a circular opening, the top of the push rod 34 is cylindrical, and an elastic damping member is provided between the blind hole 21 and the top of the push rod 34 .

[0045] Optimally, the elastic damping member is an elastic rubber ring 4; a plurality of mounting grooves 31 are arranged around the top of the top rod member 34; each mounting groove 31 is sleeved with an elastic rubber ring 4; an outer ring diameter R1 of the elastic rubber ring 4 when installed in the mounting groove 31 is larger than a diameter of the blind hole 21, so that when the top of the hole opener center positioning rod 3 is inserted into the blind hole 21, the elastic rubber ring 4 is squeezed by the inner wall surface of the blind hole 21 and the bottom surface of the corresponding mounting groove 31.

[0046] Optimally, the tool handle 2 is provided with a vent hole, which passes through the inner wall of the blind hole 21; when the top of the center positioning rod 3 of the hole opener is inserted into the blind hole 21, the air in the blind hole 21 is squeezed and discharged through the vent hole, and when the top of the center positioning rod 3 of the hole opener is pulled outward in the blind hole 21, the outside air enters the blind hole 21 through the vent hole.

[0047] Optimally, a circular shaft limiting annular platform 36 is convexly provided in the middle of the push rod 34, and the circular shaft limiting annular platform 36 surrounds the virtual center axis of the push rod 34, and the outer diameter of the circular shaft limiting annular platform 36 is larger than the inner diameter of the blind hole 21; the circular shaft limiting annular platform 36 is used to limit the direction in which the push rod 34 extends into the blind hole 21.

[0048] Specifically, a mounting threaded hole 12 is provided on the top surface of the top of the main drill bit 1 , and the mounting threaded hole 12 is used for docking and mounting with the tool handle 2 ; an external thread is provided on the outer side of the bottom of the tool handle 2 .

[0049] Specifically, when the nail head of the nail column portion 322 of the bottom rod 32 is worn, a grinder can be used to grind the nail head, or the top rod 34 can be unscrewed and removed from the spring threaded hole 332, and then the compression spring 35 can be taken out (in this way, the damaged compression spring 35 can be replaced), and then the bottom rod 32 can be removed from the spring threaded hole 332, thereby replacing a new bottom rod 32.

[0050] The use process of the cutter head device of the utility model is as follows:

[0051] Install the top of the handle 2 of the cutter head device on the rotating part of the drill (such as a hand drill) and lock it, mark the location on the wall, and place the bottom end of the bottom of the center positioning rod 3 of the hole opener opposite the positioning mark on the wall. Turn on the drill to leave a pit corresponding to the position of the positioning mark and an annular groove pre-drilled by the main drill bit 1 on the wall. Pull out the center positioning rod 3 of the hole opener by hand, and use the main drill bit 1 to drill a hole deep into the wall along the annular groove left by pre-drilling.

[0052] The above-mentioned embodiments only express several implementation methods of the utility model, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the patent of the utility model. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the utility model, and these all belong to the protection scope of the utility model. Therefore, the protection scope of the utility model patent shall be based on the attached claims.

Claims

1. A center positioning rod for a hole opener with stable positioning and easy maintenance, wherein one end of the center positioning rod (3) of the hole opener is detachably mounted in the center mounting hole of a hole opening cutter head as an accessory of the hole opener, and the other end of the center positioning rod (3) of the hole opener is used for pressing and positioning on an object to be opened, characterized in that: The hole opener center positioning rod (3) is an elastic compressible and resetting spring telescopic rod, and the hole opener center positioning rod (3) comprises a bottom rod (32), a middle rod (33), a top rod (34) and a compression spring (35); the middle rod (33) is provided with a second hollow cavity (333) for embedding the compression spring (35), and the two ends of the compression spring (35) elastically press the bottom rod (32) and the top rod (34) respectively; the bottom rod (32) and the middle rod (33) are coaxially detachably connected, and the bottom rod (32) and the middle rod (33) slide in a displaced manner relative to each other when the bottom end of the bottom of the bottom rod (32) is compressed; The middle rod (33) is coaxial with the jack top rod (34) and is detachably threaded; the top of the top rod (34) is used to be detachably mounted in the central mounting hole of the hole opening cutter head of the hole opener; the bottom end structure of the bottom of the bottom rod (32) is used to position and press against the object to be opened; the bottom end structure of the bottom of the bottom rod (32) is bullet-shaped, inverted cone-shaped or hemispherical.

2. The center positioning rod of the hole opener with stable positioning and easy maintenance according to claim 1 is characterized in that: The structure of the bottom rod (32) is in the shape of a nail with a nail cap, and the bottom rod (32) comprises a nail cap portion (321) and a nail column portion (322); the bottom end surface and the top end surface of the middle rod (33) are respectively provided with a nail through hole (331) and a spring threaded hole (332), and the nail through hole (331) and the spring threaded hole (332) both penetrate into the second hollow cavity (333); the outer diameter of the nail cap portion (321) of the bottom rod (32) is larger than the outer diameter of the nail through hole ( The inner hole diameter of the bottom rod (32) is smaller than the inner hole diameter of the nail through hole (331), and the nail column (322) of the bottom rod (32) extends into the nail through hole (331); the spring threaded hole (332) is provided with an internal thread, and the bottom end of the top rod (34) is provided with an external thread. The bottom end of the top rod (34) is screwed and installed with the external thread and the spring threaded hole (332) provided with the internal thread.

3. The center positioning rod of the hole opener with stable positioning and easy maintenance according to claim 1 is characterized in that: A circular shaft limiting annular platform (36) is protruded from the middle of the push rod (34), and the circular shaft limiting annular platform (36) surrounds the virtual central axis of the push rod (34); the circular shaft limiting annular platform (36) is used to limit the direction in which the push rod (34) extends into the central mounting hole.

4. A hole-opening cutter head using the stable and easy-to-maintain center positioning rod of a hole opener as claimed in any one of claims 1 to 3, as an accessory of the hole opener, used for drilling holes in cooperation with a drilling rig of the hole opener, characterized in that: The hole-opening cutter head comprises the hole-opening device center positioning rod (3), a main drill bit (1) and a shank (2); the main drill bit (1) is a cylindrical drill bit structure provided with a first hollow cavity (11); the bottom surface of the bottom of the main drill bit (1) is provided with a drill hole for opening a hole; the shank (2) serves as an intermediate connecting piece between a drilling machine and the main drill bit (1); the top of the shank (2) is used to be installed on the rotating part of the drilling machine; the bottom surface of the bottom of the shank (2) is provided with a blind hole (21); the top of the push rod (34) extends into the first hollow cavity (11) of the main drill bit (1) and can be inserted into the blind hole (21) in a pluggable manner; The blind hole (21) is located at the center of the bottom surface of the bottom of the handle (2); When the hole opener center positioning rod (3) does not press against the object to be opened, the bottom end of the bottom of the bottom rod (32) protrudes from the drilling end surface of the main drill bit (1).

5. The hole-opening cutter head for the center positioning rod of the hole-opening tool with stable positioning and easy maintenance according to claim 4, characterized in that: The blind hole (21) has a circular opening, the top of the push rod (34) is cylindrical, and an elastic damping member is provided between the blind hole (21) and the top of the push rod (34).

6. The hole-opening cutter head for the center positioning rod of the hole-opening tool with stable positioning and easy maintenance according to claim 5, characterized in that: The elastic damping member is an elastic rubber ring (4); a plurality of mounting grooves (31) are arranged around the top of the top rod member (34); each mounting groove (31) is sleeved with an elastic rubber ring (4); the outer ring diameter (R1) of the elastic rubber ring (4) when installed in the mounting groove (31) is larger than the diameter of the blind hole (21), so that when the top of the hole opener center positioning rod (3) is inserted into the blind hole (21), the elastic rubber ring (4) is squeezed by the inner wall surface of the blind hole (21) and the bottom surface of the corresponding mounting groove (31).

7. The hole-opening cutter head for the center positioning rod of the hole-opening tool with stable positioning and easy maintenance according to claim 6, characterized in that: The knife handle (2) is provided with a ventilation hole, and the ventilation hole penetrates the inner wall surface of the blind hole (21); when the top of the hole opener center positioning rod (3) is inserted into the blind hole (21), the air in the blind hole (21) is squeezed out through the ventilation hole; when the top of the hole opener center positioning rod (3) is pulled outward from the blind hole (21), the outside air enters the blind hole (21) through the ventilation hole.

8. The hole-opening cutter head for the center positioning rod of the hole-opening tool with stable positioning and easy maintenance according to claim 5, characterized in that: A circular shaft limiting annular platform (36) is protrudingly provided in the middle of the push rod (34), the circular shaft limiting annular platform (36) surrounds the virtual central axis of the push rod (34), and the outer diameter of the circular shaft limiting annular platform (36) is greater than the inner diameter of the blind hole (21); the circular shaft limiting annular platform (36) is used to limit the direction in which the push rod (34) extends into the blind hole (21).

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