A multi-stage stepped drill bit and axial force self-adaptive balancing device thereof

Abstract

The present application relates to the technical field of cutters, and discloses a multistage stepped drill bit and an axial force self-adaptive balancing device thereof, which comprises a drill handle fixedly installed at one end of a drill bit body, the cross section of the drill handle is arranged in a regular hexagon, one end of the drill handle is provided with a rotating shaft fixedly connected with a driving source, three clamping blocks for clamping the drill handle are slidably installed at the end of the rotating shaft, the clamping blocks are arranged in a circle, and an elastic rod is fixedly connected between every two adjacent clamping blocks, the multistage stepped drill bit is used for driving six telescopic rods to synchronously perform centripetal movement and shrinkage by means of a rotating sleeve, and the rollers can abut against six surfaces of the drill handle, when the drill handle moves, the corresponding rollers are offset, the corresponding rotating rods are rotated, the rollers at the other end of the corresponding rotating rods are reversely offset by the lever principle, the drill handle is assisted to keep linear movement, and no matter in which direction the drill handle moves, the movement of the drill handle can be effectively guided, and the axial force borne by the drill bit is kept balanced.

Description

Technical Field

[0001] This invention relates to the field of cutting tool technology, specifically to a multi-stage stepped drill bit and its axial force adaptive balancing device. Background Technology

[0002] Multi-stage stepped drill bits, also known as step drills, tiered drills, or pagoda drills, are specially designed drilling tools. Their cutting section consists of multiple concentric cylinders with progressively increasing diameters, forming a stepped structure. They are primarily used for efficiently machining holes of different diameters, with significant advantages, especially in thin sheet materials. The drill bit integrates multiple cutting edges of different diameters, each corresponding to a fixed hole diameter. The steps are smoothly connected by tapered transition sections, reducing cutting resistance and dispersing stress, preventing drill bit jamming. A single stepped drill can continuously enlarge holes of multiple diameters, eliminating the need for repeated drill bit changes and improving efficiency. The axial force of the drill bit refers to the resultant cutting force generated along the drill bit's axis during drilling. Its balance is crucial for ensuring drilling accuracy and drill bit life; imbalance can lead to drill deviation, drill bit breakage, or even equipment damage.

[0003] Multi-stage stepped drill bits are often used for drilling holes in sheet metal. When the drill bit penetrates the sheet metal, the material's resistance to the drill tip drops sharply. Due to the mechanical gap and elastic deformation between the drill bit and the feed system, the sudden release of stored elastic potential energy after the resistance drops can cause the drill bit to cut into the sheet metal uncontrollably with an excessive feed rate. The axial force on the drill bit will become unbalanced, resulting in impact-induced axial movement. Moreover, the greater the axial force applied to the drill bit, the greater the accumulated elastic potential energy before penetration, and the greater the amplitude of the drill bit's axial movement when the resistance changes abruptly, leading to drilling deviation or equipment damage. To address this, we propose a multi-stage stepped drill bit and its axial force adaptive balancing device. Summary of the Invention

[0004] The purpose of this invention is to provide a multi-stage stepped drill bit and its axial force adaptive balancing device to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: an axial force adaptive balancing device, comprising a drill shank fixedly installed at one end of a drill bit body, the drill shank having a cross-section of a regular hexagon, one end of which is provided with a rotating shaft fixedly connected to a drive source, three clamping blocks for clamping the drill shank being slidably installed at the end of the rotating shaft, the clamping blocks being arranged circumferentially, an elastic rod being fixedly connected between every two adjacent clamping blocks, a first wedge block being fixedly installed on each clamping block, the inclined surface of each first wedge block being set in an inclined arc shape, a sleeve being threaded onto the rotating shaft, one end of the sleeve being tapered and fitted onto the drill shank, a first wedge ring cooperating with the first wedge block being fixedly installed on the inner wall of the sleeve, six telescopic rods being provided inside the sleeve, the six telescopic rods being connected end to end and forming a regular hexagon, and two rollers for limiting the drill shank being provided on one side of each telescopic rod.

[0006] Preferably, three sliding rods limited by elastic rods are slidably installed at the end of the rotating shaft. Each sliding rod abuts against a corresponding elastic rod on one side, and one end of each sliding rod is fixedly connected to a corresponding telescopic rod. A connecting rod is fixedly installed at one end of each clamping block, and one end of each connecting rod is also fixedly connected to a corresponding telescopic rod.

[0007] Preferably, a second wedge block is fixedly installed on each of the telescopic rods, and the inclined surface of each second wedge block is also set as an inclined arc shape. A second wedge ring that cooperates with the second wedge block is fixedly installed on the inner wall of the sleeve.

[0008] Preferably, a rotating rod is rotatably connected between every two corresponding rollers, and the center point of each rotating rod is rotatably connected to a corresponding telescopic rod.

[0009] Preferably, a plurality of arc-shaped plates are fixedly installed at one end of the sleeve. The arc-shaped plates are arranged in a circle. A plurality of limiting strips are fixedly installed on the inner wall of each arc-shaped plate. The limiting strips are also arranged in a circle and are parallel to the axial force of the drill bit. A plurality of limiting grooves for limiting the limiting strips are provided on the rotating shaft. The limiting grooves are arranged in a circle and their length is greater than the length of the limiting strips.

[0010] Preferably, the arc-shaped plate is made of an elastic material, and one end of each arc-shaped plate is raised. A push ring for limiting the arc-shaped plate is slidably installed on the sleeve.

[0011] Preferably, each face of the drill shank is fixedly equipped with a vertical locking bar, each vertical locking bar is arranged parallel to the axial force of the drill bit, and each clamping block is provided with a vertical locking groove on one side for limiting the vertical locking bar.

[0012] Preferably, each surface of the drill shank is provided with a plurality of transverse slots, each transverse slot is perpendicular to the axial force of the drill bit, and each clamping block is fixedly installed with a transverse clamping strip that cooperates with the transverse slot on one side.

[0013] Preferably, a pressure sensing plate for controlling the feed amount of the shaft is fixedly installed at the end of the shaft, and one side of the pressure sensing plate abuts against the end of the drill shank.

[0014] A multi-stage stepped drill bit, wherein the drill bit body is provided with the aforementioned axial force adaptive balancing device, and the drill bit body is provided with two chip removal grooves, each of which is spirally arranged.

[0015] Compared with the prior art, the beneficial effects of the present invention are:

[0016] This invention utilizes a rotating sleeve to drive six telescopic rods to synchronously retract in a centripetal motion. The rollers can abut against the six surfaces of the drill shank, ensuring that each surface of the drill shank receives uniform force. When the drill shank shifts, it pushes the corresponding roller to deflect and causes the corresponding rotating rod to rotate. The roller at the other end of the corresponding rotating rod will deflect in the opposite direction due to the lever principle, helping the drill shank maintain a straight path. At the same time, the second wedge ring limits the second wedge block, the elastic rod limits the sliding rod, and the clamping block limits the connecting rod, preventing the drill shank from causing all rollers and the telescopic rods to shift as a whole. Regardless of the direction in which the drill shank shifts, it can effectively guide the shifting of the drill shank and keep the axial force on the drill bit balanced.

[0017] This invention utilizes three clamping blocks to hold a hexagonal drill shank. Regardless of how the drill shank is inserted, the plane of the clamping blocks always abuts against the plane of the drill shank, increasing the contact area and improving the stability of the drill shank clamping. Furthermore, the vertical groove limits the vertical clamping bar, and the horizontal groove limits the horizontal clamping bar, further enhancing the clamping strength of the clamping blocks on the drill shank. The vertical clamping bar is parallel to the axial force of the drill bit, while the horizontal groove is perpendicular to the axial force of the drill bit, ensuring that the drill shank is well limited in both the horizontal and vertical directions. This reduces the elastic deformation amplitude of the drill shank when the drill bit body encounters resistance. When the drill shank moves, the good clamping effect of the clamping blocks can also reduce the amplitude of the movement of the drill shank.

[0018] This invention utilizes a push ring to limit the arc-shaped plate, pressing one end of the arc-shaped plate against the rotating shaft, causing the limiting strip to insert into the corresponding limiting groove, further locking the sleeve position, preventing the threads from loosening, or preventing the sleeve from rotating due to excessive elastic potential energy when the drill shank moves. This ensures that the first and second wedge rings inside the sleeve always limit the first and second wedge blocks, maintaining a stable clamping and guiding of the drill shank. Attached Figure Description

[0019] Figure 1This is a schematic diagram of the overall structure of the present invention;

[0020] Figure 2 This is a schematic diagram of the drill shank structure of the present invention;

[0021] Figure 3 This is a schematic diagram of the internal structure of the sleeve of the present invention;

[0022] Figure 4 For the present invention Figure 3 Enlarged schematic diagram of the inner A region structure;

[0023] Figure 5 This is a schematic diagram of the sleeve structure of the present invention;

[0024] Figure 6 This is a schematic diagram of the clamping block structure of the present invention;

[0025] Figure 7 This is a schematic diagram of the telescopic rod structure of the present invention;

[0026] Figure 8 This is a schematic diagram of the roller structure of the present invention;

[0027] Figure 9 For the present invention Figure 8 Enlarged schematic diagram of the inner B region structure.

[0028] In the diagram: 1. Drill bit body; 2. Chip removal groove; 3. Drill shank; 4. Rotary shaft; 5. Sleeve; 6. Clamping block; 7. First wedge block; 8. First wedge ring; 9. Elastic rod; 10. Pressure sensing plate; 11. Sliding rod; 12. Telescopic rod; 13. Rotating rod; 14. Roller; 15. Connecting rod; 16. Second wedge block; 17. Second wedge ring; 18. Vertical clamping strip; 19. Vertical clamping groove; 20. Horizontal clamping strip; 21. Horizontal clamping groove; 22. Arc plate; 23. Limiting strip; 24. Limiting groove; 25. Push ring. Detailed Implementation

[0029] 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.

[0030] Please see Figure 1-9This invention provides a technical solution: an axial force adaptive balancing device, comprising a drill shank 3 fixedly installed at one end of a drill bit body 1 (the drill bit body 1 is an existing stepped drill bit, so this invention will not elaborate further). The drill shank 3 has a hexagonal cross-section, and one end of it is provided with a rotating shaft 4 fixedly connected to a drive source. Three clamping blocks 6 for clamping the drill shank 3 are slidably installed at the end of the rotating shaft 4. The clamping blocks 6 are arranged circumferentially. Regardless of how the drill shank 3 is inserted, when the clamping blocks 6 clamp the drill shank 3, each clamping block 6 can make direct contact with the drill shank 3. Compared with traditional circular drill shanks and arc-shaped clamping blocks, this increases the contact area and improves the clamping stability. Vertical locking strips 18 are fixedly installed on each surface of the drill shank 3, and each vertical locking strip 18 is parallel to the axial force of the drill bit. Each clamping block 6 has a vertical groove 19 on one side for limiting the vertical clamping strip 18. Each surface of the drill shank 3 has several horizontal grooves 21, each perpendicular to the axial force of the drill bit. Each clamping block 6 has a horizontal clamping strip 20 fixedly installed on one side, cooperating with the horizontal grooves 21. The limiting effect of the vertical grooves 19 on the vertical clamping strip 18 and the limiting effect of the horizontal grooves 21 on the horizontal clamping strip 20 further improves the clamping strength of the clamping blocks 6 on the drill shank 3. Furthermore, the vertical clamping strip 18 is parallel to the axial force of the drill bit, while the horizontal grooves 21 are perpendicular to the axial force of the drill bit, ensuring that the drill shank 3 is well limited in both the horizontal and vertical directions, reducing the elastic deformation amplitude of the drill shank 3 when the drill bit body 1 encounters resistance. When the resistance to the drill bit body 1 decreases and the drill shank 3 moves erratically, the good clamping effect of the clamping block 6 can also reduce the erratic movement of the drill shank 3. An elastic rod 9 is fixedly connected between every two adjacent clamping blocks 6. A first wedge block 7 is fixedly installed on each clamping block 6. The inclined surface of each first wedge block 7 is set as an inclined arc. A sleeve 5 is threaded on the rotating shaft 4. One end of the sleeve 5 is tapered and is fitted onto the drill shank 3. A first wedge ring 8 that cooperates with the first wedge block 7 is fixedly installed on the inner wall of the sleeve 5. A pressure sensing plate 10 for controlling the feed amount of the rotating shaft 4 is fixedly installed at the end of the rotating shaft 4. One side of the pressure sensing plate 10 abuts against the end of the drill shank 3. In the initial state, the elastic force of the elastic rod 9 pushes the two adjacent clamping blocks 6 to both sides, so that the clamping blocks 6 The sleeve 5 is opened to facilitate the insertion of drill shanks 3 of different sizes, ensuring that the inclined surface of each first wedge block 7 is in contact with the inclined surface of the first wedge ring 8. After the drill shank 3 is inserted into the sleeve 5, the sleeve 5 is rotated. Since the sleeve 5 is connected to the rotating shaft 4 by threads, the sleeve 5 drives the first wedge ring 8 to rotate, continuously moving towards the rotating shaft 4. Through the cooperation between the inclined surfaces of the first wedge block 7 and the first wedge ring 8, the three clamping blocks 6 will move synchronously towards the center until the clamping blocks 6 abut against the straight surface of the drill shank 3, thus completing the clamping of the drill shank 3. During the use of the drill bit, the resistance experienced by the drill bit body 1 continuously increases, and the amplitude of the elastic deformation of the drill shank 3 also continuously increases. The pressure sensed by the pressure sensing plate 10 increases accordingly. When the end of the drill bit body 1 penetrates the plate, the resistance it experiences decreases instantaneously.The pressure sensed by the pressure sensor plate 10 decreases instantaneously, releasing elastic potential energy. The axial force on the drill bit becomes unbalanced, causing the drill bit body 1 and drill shank 3 to move erratically. The pressure sensor plate 10 then controls the rotating shaft 4 to reduce the feed rate, decreasing the axial force on the drill bit and preventing excessive erratic movement that could lead to misalignment of the holes in the sheet metal.

[0031] Furthermore, the sleeve 5 is equipped with six telescopic rods 12, which are connected end to end and form a regular hexagon. Each telescopic rod 12 has two rollers 14 on one side for limiting the drill shank 3. A rotating rod 13 is rotatably connected between each pair of corresponding rollers 14. The center point of each rotating rod 13 is rotatably connected to the corresponding telescopic rod 12. Three sliding rods 11, which are limited by elastic rods 9, are slidably installed at the end of the rotating shaft 4. One side of each sliding rod 11 abuts against the corresponding elastic rod 9. One end of each sliding rod 11 is fixedly connected to the corresponding telescopic rod 12. A connecting rod 15 is fixedly installed at one end of each clamping block 6. One end of each connecting rod 15 is also fixed to the corresponding telescopic rod 12. The connection is as follows: each telescopic rod 12 is fixedly equipped with a second wedge block 16, and the inclined surface of each second wedge block 16 is also set as an inclined arc. A second wedge ring 17 that cooperates with the second wedge block 16 is fixedly installed on the inner wall of the sleeve 5. In the initial state, the elastic rod 9 is in the extended state. The elastic rod 9 pushes two adjacent clamping blocks 6 to move in opposite directions. The clamping blocks 6 drive three of the telescopic rods 12 to perform synchronous centrifugal motion through the connecting rod 15. At this time, the elastic rod 9 does not apply pressure to the sliding rod 11. The elasticity of the telescopic rod 12 itself causes it to extend. The six telescopic rods 12 will perform centrifugal motion and extend synchronously, and the three sliding rods 11 always abut against the corresponding elastic rod 9. Each second wedge block 16 The inclined surface of the sleeve 5 always abuts against the second wedge ring 17. When the sleeve 5 is rotated, the three clamping blocks 6 will drive the three connecting rods 15 and the three telescopic rods 12 to move centripetally. During the contraction of the three elastic rods 9, they will also push the three sliding rods 11 and the three telescopic rods 12 to move centripetally, so that the six telescopic rods 12 can move centripetally and contract synchronously, preventing uneven elasticity among the telescopic rods 12 from causing asynchronous contraction or jamming. During the contraction of the telescopic rods 12, the second wedge ring 17 always abuts against the second wedge block 16, further assisting the six telescopic rods 12 to contract synchronously. After the sleeve 5 has finished rotating, the six telescopic rods 12 will push the roller 14 to abut against the six surfaces of the drill shank 3, so that each of the drill shank 3... The drill bit is able to be evenly stressed, ensuring the balance of the axial force. When the drill shank 3 moves, it will tilt and push one of the corresponding rollers 14 to deflect, causing the corresponding rotating rod 13 to rotate. The roller 14 at the other end of the corresponding rotating rod 13 will deflect in the opposite direction due to the lever principle, helping the drill shank 3 to maintain straight movement. At the same time, the second wedge ring 17 limits the second wedge block 16, the elastic rod 9 limits the slide rod 11, and the clamping block 6 limits the connecting rod 15, preventing the drill shank 3 from causing all rollers 14 and the telescopic rod 12 to deflect as a whole. No matter which direction the drill shank 3 moves, it can effectively guide the movement of the drill shank 3 and keep the axial force on the drill bit balanced.

[0032] Furthermore, several arc-shaped plates 22 are fixedly installed at one end of the sleeve 5. The arc-shaped plates 22 are arranged in a circle, and several limiting strips 23 are fixedly installed on the inner wall of each arc-shaped plate 22. The limiting strips 23 are also arranged in a circle and are parallel to the axial force of the drill bit. Several limiting grooves 24 are provided on the rotating shaft 4 to limit the limiting strips 23. The limiting grooves 24 are arranged in a circle and their length is greater than the length of the limiting strips 23. The arc-shaped plates 22 are made of elastic material, and one end of each arc-shaped plate 22 is raised. A push ring 25 for limiting the arc-shaped plates 22 is slidably installed on the sleeve 5. When the sleeve 5 is not rotating, the push ring 25 does not move. The arc-shaped plate 22 is positioned, with its end remaining raised. The limiting strip 23 is not inserted into the limiting groove 24, thus not obstructing the rotation of the sleeve 5. After the sleeve 5 has rotated, the push ring 25 is pushed to coincide with the arc-shaped plate 22, and the raised end of the arc-shaped plate 22 is pressed against the rotating shaft 4, causing the limiting strip 23 to be inserted into the corresponding limiting groove 24. This further locks the position of the sleeve 5, preventing the threads from loosening or the sleeve 5 from rotating due to excessive elastic potential energy when the drill shank 3 moves. This ensures that the first wedge ring 8 and the second wedge ring 17 inside the sleeve 5 always limit the first wedge block 7 and the second wedge block 16, maintaining a stable clamping and guiding of the drill shank 3.

[0033] The present invention provides a multi-stage stepped drill bit, including a drill bit body 1, the drill bit body 1 being provided with the aforementioned axial force adaptive balancing device, and the drill bit body 1 being provided with two chip removal grooves 2, each chip removal groove 2 being spirally arranged to facilitate faster discharge of chips and debris.

[0034] Specifically, firstly, the push ring 25 is pushed away from its position coinciding with the arc-shaped plate 22, and the sleeve 5 is rotated away from the rotating shaft 4. The elastic force of the elastic rod 9 pushes the two adjacent clamping blocks 6 to both sides, causing the clamping blocks 6 to open. The clamping blocks 6 drive three of the telescopic rods 12 to perform synchronous centrifugal motion. The elasticity of the telescopic rods 12 causes them to extend. All six telescopic rods 12 will perform centrifugal motion and extend synchronously. Then, the drill shank 3 is inserted into the sleeve 5, with one end abutting against the pressure sensing plate 10. Then, the sleeve 5 is rotated towards the rotating shaft 4. As the sleeve 5 drives the first wedge-shaped ring 8 to rotate, it will continuously move towards the rotating shaft 4. The first wedge ring 8 pushes the three first wedge blocks 7 and the three clamping blocks 6 to move centripetally in sync. The vertical locking strip 18 will be inserted into the corresponding vertical locking slot 19, and the horizontal locking strip 20 will be inserted into the horizontal locking slot 21. At the same time, the three clamping blocks 6 will drive the three connecting rods 15 and the three telescopic rods 12 to move centripetally. The three elastic rods 9 will push the three sliding rods 11 and the three telescopic rods 12 to move centripetally, so that the six telescopic rods 12 will retract centripetally in sync. During the retraction of the telescopic rods 12, the second wedge ring 17 always abuts against the second wedge block 16, further assisting the six telescopic rods 12 to retract synchronously. Finally, the six telescopic rods 12 push the rollers 14 to abut against the six sides of the drill shank 3, and the three clamping blocks 6 abut against the straight surface of the drill shank 3, completing the clamping of the drill shank 3. Then, the push ring 25 is pushed to the position coinciding with the arc plate 22, and one end of the arc plate 22 is raised and pressed against the rotating shaft 4, so that the limiting strip 23 is inserted into the corresponding limiting groove 24, further locking the position of the sleeve 5. During the use of the drill bit, the resistance experienced by the drill bit body 1 continuously increases, and the amplitude of the elastic deformation of the drill shank 3 also continuously increases. The pressure sensed by the pressure sensing plate 10 increases accordingly. When the end of the drill bit body 1 penetrates the plate, the resistance it experiences... As the force decreases instantaneously, the pressure sensed by the pressure sensing plate 10 also decreases instantaneously. At this moment, the elastic potential energy is released, the axial force of the drill bit is unbalanced, and the drill bit body 1 and the drill shank 3 move sideways. The pressure sensing plate 10 will control the rotating shaft 4 to reduce the feed rate, thereby reducing the axial force on the drill bit. At the same time, the drill shank 3 will push the corresponding roller 14 to deflect and cause the corresponding rotating rod 13 to rotate. The roller 14 at the other end of the corresponding rotating rod 13 will deflect in the opposite direction, assisting the drill shank 3 to maintain straight-line movement. No matter which direction the drill shank 3 moves, it can effectively guide the movement of the drill shank 3 and keep the axial force on the drill bit balanced.

[0035] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0036] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An axial force adaptive balancing device, comprising a drill shank (3) fixedly installed at one end of a drill bit body (1), characterized in that: The drill shank (3) has a hexagonal cross-section, with a rotating shaft (4) fixedly connected to a drive source at one end. Three clamping blocks (6) for holding the drill shank (3) are slidably mounted on the end of the rotating shaft (4). The clamping blocks (6) are arranged circumferentially, and an elastic rod (9) is fixedly connected between every two adjacent clamping blocks (6). A first wedge block (7) is fixedly mounted on each clamping block (6), and the inclined surface of each first wedge block (7) is set as an inclined arc. A sleeve (5) is threaded on the shaft (4). One end of the sleeve (5) is tapered and is fitted onto the drill shank (3). A first wedge ring (8) that cooperates with the first wedge block (7) is fixedly installed on the inner wall of the sleeve (5). Six telescopic rods (12) are provided inside the sleeve (5). The six telescopic rods (12) are connected end to end and form a regular hexagon. Each telescopic rod (12) has two rollers (14) on one side for limiting the drill shank (3). The end of the rotating shaft (4) is slidably mounted with three sliding rods (11) limited by elastic rods (9). Each sliding rod (11) abuts against the corresponding elastic rod (9) on one side. One end of each sliding rod (11) is fixedly connected to the corresponding telescopic rod (12). One end of each clamp (6) is fixedly mounted with a connecting rod (15). One end of each connecting rod (15) is also fixedly connected to the corresponding telescopic rod (12).

2. The axial force adaptive balancing device according to claim 1, characterized in that: Each of the telescopic rods (12) is fixedly installed with a second wedge block (16), and the inclined surface of each second wedge block (16) is also set as an inclined arc. A second wedge ring (17) that cooperates with the second wedge block (16) is fixedly installed on the inner wall of the sleeve (5).

3. The axial force adaptive balancing device according to claim 2, characterized in that: A rotating rod (13) is rotatably connected between each pair of corresponding rollers (14), and the center point of each rotating rod (13) is rotatably connected to the corresponding telescopic rod (12).

4. The axial force adaptive balancing device according to claim 1, characterized in that: A plurality of arc-shaped plates (22) are fixedly installed at one end of the sleeve (5). The arc-shaped plates (22) are arranged in a circle. A plurality of limiting strips (23) are fixedly installed on the inner wall of each arc-shaped plate (22). The limiting strips (23) are also arranged in a circle and are set parallel to the axial force of the drill bit. A plurality of limiting grooves (24) for limiting the limiting strips (23) are provided on the rotating shaft (4). The limiting grooves (24) are arranged in a circle and their length is greater than the length of the limiting strips (23).

5. An axial force adaptive balancing device according to claim 4, characterized in that: The arc plate (22) is made of elastic material, and one end of each arc plate (22) is raised. A push ring (25) for limiting the arc plate (22) is slidably installed on the sleeve (5).

6. The axial force adaptive balancing device according to claim 5, characterized in that: Each face of the drill shank (3) is fixedly equipped with a vertical locking strip (18), each vertical locking strip (18) is arranged parallel to the axial force of the drill bit, and each clamping block (6) is provided with a vertical locking groove (19) on one side for limiting the vertical locking strip (18).

7. An axial force adaptive balancing device according to claim 6, characterized in that: Each of the drill shank (3) has several transverse slots (21) on each surface. Each transverse slot (21) is perpendicular to the axial force of the drill bit. Each of the clamping blocks (6) has a transverse clamping strip (20) fixedly installed on one side to cooperate with the transverse slot (21).

8. The axial force adaptive balancing device according to claim 7, characterized in that: A pressure sensing plate (10) for controlling the feed amount of the shaft (4) is fixedly installed at the end of the shaft (4), and one side of the pressure sensing plate (10) abuts against the end of the drill shank (3).

9. A multi-stage stepped drill bit, characterized in that: The drill bit body (1) is provided with an axial force adaptive balancing device including any one of claims 1 to 8, and the drill bit body (1) is provided with two chip removal grooves (2), each of the chip removal grooves (2) being spirally arranged.

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