Variable position drill chuck

Abstract

The present application belongs to the technical field of drill rod clamping device, solves the problem that the low precision of drill rod opening and closing leads to the problem that the drill rod centering is low, and provides a variable position drill rod clamping device, which comprises a support frame, a drill rod clamping assembly and a constraint assembly, the drill rod clamping assembly is arranged in the mounting groove on the support frame through a driving element, the constraint assembly comprises a main body, a displacement rod and a compression block, the main body is connected with the support frame, the main body is provided with a limiting block with a guide groove, the displacement rod is connected with the compression block and a sliding column which is slidably embedded in the guide groove, the compression block and the main body are provided with a compression block reset spring which provides a reset force to the compression block, the displacement rod and the compression block are provided with a displacement rod reset spring which provides a reset force to the displacement rod, and the sliding column has an initial position, a grab rod position, a reset position, a guard rod position and a zero position in the guide groove in sequence. The device can automatically switch between two mechanical limiting states, reduces the cost and improves the centering of the drill rod.

Description

Technical Field

[0001] This invention relates to the field of rod clamping device technology, and specifically to a variable position rod clamping device. Background Technology

[0002] During downhole anchor bolt support, when drilling holes for the drill pipe is required, the drill pipe is quite long, and the drill box alone cannot completely guarantee its alignment. Therefore, a clamping mechanism is needed to protect the drill pipe and keep the swing amplitude of the drill pipe head within a certain range. After the drill pipe is drilled, it needs to be withdrawn with the drill box for subsequent anchoring processes. At this time, the clamping mechanism needs to hold the drill pipe and pull it out of the borehole.

[0003] Existing clamping mechanisms are divided into general clamping mechanisms and large-aperture clamping mechanisms. Both use hydraulics as the driving force. When hydraulically driven clamping mechanisms open and close, the control precision is relatively low. If the hydraulic cylinder drive time is too long, the clamping force of the clamping mechanism is too large, failing to provide a rod protection function. If the hydraulic drive time is too short, the strokes on the left and right sides of the hydraulic cylinder are inconsistent. If drilling is performed under these conditions, the concentricity between the drill rod's drilling point and the drill box center will be low, and the drill rod is prone to swaying during drilling, affecting the hole formation rate and the service life of the drill rod. When using clamping mechanisms, the concentricity of the drill rod during drilling is manually controlled by the operator. That is, the operator manually adjusts the clamping position based on experience to control the concentricity of the drill rod during drilling. However, manual adjustment of the clamping position often requires multiple adjustments. For inexperienced operators, if the adjusted clamping position deviates too much, it will also increase the probability of drill rod damage.

[0004] To address the above issues, some scholars and downhole workers have proposed several improvement methods: 1) Adjusting the alignment of the clamp by modifying the process flow. First, the clamp is fully closed. After full closure, the alignment is good, but it cannot protect the rod. At this point, the cylinder is reversed, and the clamp mechanism opens a certain distance, which can protect the rod. However, this method takes a long time, and the size of the clamp opening cannot be guaranteed during the opening process, and the accuracy is not very high; 2) Changing the power source of the clamp, changing the clamp from hydraulic drive to electric drive. This method improves the accuracy of clamp opening and closing, but the use of electric components downhole requires explosion-proof treatment, and the motor is large, reducing the compactness of the clamp structure; 3) Using a servo hydraulic cylinder instead of a general hydraulic cylinder for driving. The servo hydraulic cylinder can better guarantee the accuracy of clamp opening and closing and has a higher structural compactness. However, the servo hydraulic cylinder has high requirements for hydraulic oil quality. The downhole environment is harsh, and the oil is easily contaminated. Using a servo hydraulic cylinder increases the operating cost of the clamp mechanism and reduces its operational reliability. Summary of the Invention

[0005] In order to solve the above-mentioned technical problems, or at least partially solve the above-mentioned technical problems, this disclosure provides a variable position clamping device.

[0006] A variable position clamping device, comprising:

[0007] A support frame, on which mounting slots are provided;

[0008] The drill bit clamping assembly is slidably disposed in the mounting groove. The drill bit clamping assembly includes two horizontally symmetrically arranged drill bit clamping blocks. Each of the two drill bit clamping blocks has a chuck for clamping the drill rod on one side opposite to the other side. A driving component is provided between the other side of the two drill bit clamping blocks and the support frame. The driving component drives the drill bit clamping blocks to reciprocate.

[0009] A constraint assembly is disposed between the opposite sides of two clamping blocks. The constraint assembly includes a main body, a displacement rod, and a compression block. The main body is connected to the support frame. A limiting block is fixed to the main body. A guide groove with its ends connected is disposed in the limiting block. One end of the displacement rod is connected to the compression block. A sliding column is disposed at the other end of the displacement rod. The sliding column is slidably embedded in the guide groove. The clamping blocks drive the compression block to move. The compression block drives the displacement rod to move. The displacement rod drives the sliding column to move along the guide groove. A compression block return spring is disposed between the compression block and the main body. The compression block can move relative to the main body in the axial direction of the compression block return spring. The compression block return spring provides a return force to the compression block. A displacement rod return spring is disposed between the displacement rod and the compression block. The displacement rod return spring provides a return force to the displacement rod.

[0010] The sliding trajectory of the sliding column in the guide groove has an initial position, a grab bar position, a reset position, a guard bar position, and a zero position. The initial position and the zero position are on the same horizontal line and are both higher than the guard bar position. The guard bar position is higher than the reset position, and the reset position is higher than the grab bar position.

[0011] Optionally, the limiting block includes a first limiting block and a second limiting block. The first limiting block has a first groove, and the second limiting block has a second groove. The first groove and the second groove are the same shape, forming a closed guide groove. One end of the sliding column is slidably embedded in the first groove, and the other end is slidably embedded in the second groove.

[0012] Optionally, the spring constant of the compression block return spring is greater than that of the displacement rod return spring.

[0013] Optionally, the width of the guide groove is 1.1 to 1.5 times the diameter of the slide column.

[0014] Optionally, the horizontal distance between the center position of the slide block when it passes the initial position and the center position of the slide block when it passes the grab bar position is the maximum displacement of the compression block, and the horizontal distance between the center position of the slide block when it passes the initial position and the center position of the slide block when it passes the grab bar position is greater than twice the horizontal distance between the center position of the slide block when it passes the grab bar position and the center position of the slide block when it passes the guard bar position.

[0015] Optionally, the guide groove includes an inner wall and an outer wall;

[0016] The area from the initial position to the grab bar position is the downward guide zone. When passing the grab bar position, the outer circumference of the sliding column is tangent to the bottom inflection point arc of the inner sidewall.

[0017] When the two clamping blocks open for the first time and the opening and closing width is at its maximum, the sliding column is in its initial position. At this time, the compression block separates from the clamping block, and the compression block return spring and the displacement rod return spring are in their natural length state.

[0018] When the two clamping blocks close for the first time, and the opening and closing width between the two clamping blocks is less than the diameter of the drill rod, the sliding rod is in the gripping rod position. At this time, the compression block is in contact with the clamping block, the compression block return spring is in a compressed state, and the displacement rod return spring is in a compressed state.

[0019] Optionally, the downward guide zone includes a vertical section and an inclined section, with the portion of the outer wall located in the vertical section parallel to the vertical centerline of the limiting block, and the portion of the outer wall located in the inclined section inclined toward the vertical centerline of the limiting block.

[0020] Optionally, the grab lever position to zero is the upward guide zone;

[0021] The upward guide area includes a first upward area and a second upward area. The first upward area is from the gripper position to the reset position, and the second upward area is from the guard bar position to the zero position. When passing the reset position, the outer circumference of the sliding column is tangent to the arc of the top inflection point of the inner wall in the first upward area. When passing the guard bar position, the outer circumference of the sliding column is tangent to the arc of the bottom inflection point of the outer wall in the second upward area. The horizontal distance from the center position of the sliding column when passing the reset position to the vertical center line of the limit block is less than the horizontal distance from the center position of the sliding column when passing the guard bar position to the vertical center line of the limit block.

[0022] The sliding column moves from the zero position to the initial position through the top inflection point of the inner wall;

[0023] The inner wall portions located in the downward guide area and the upward guide area are inclined toward the vertical center line of the limiting block, while the outer wall portion located in the upward guide area is inclined toward the vertical center line of the limiting block.

[0024] Optionally, when the two clamping blocks open for the second time, the compression block return spring is in a compressed state, and the compression block return spring provides a force toward the compression block to the displacement rod, the displacement rod return spring is in a compressed state, and the displacement rod return spring provides an upward force to the displacement rod, at which time the slide is in the reset position;

[0025] When the two clamping blocks close for the second time, the clamping blocks drive the compression block to move. The compression block and the compression block return spring drive the displacement rod to move. The displacement rod drives the sliding column to move along the guide groove to the guard rod position. At this time, the compression block return spring is in a compressed state, and the displacement rod return spring is in a compressed state.

[0026] When the two clamping blocks open for the third time, the compression block return spring provides a force toward the compression block to the displacement rod, and the compression block return spring is in a compressed state. The displacement rod return spring provides an upward force to the displacement rod. At this time, the sliding column is in the zero position, and the displacement rod return spring is in its natural length state.

[0027] Optionally, when the slide bar moves from the zero position to the initial position, the compression block return spring provides a force toward the compression block to the displacement rod, and the displacement rod return spring provides a downward force to the displacement rod.

[0028] The technical solution provided in this disclosure has the following advantages compared with the prior art:

[0029] This disclosure provides a variable-position drill bit clamping device. This device features a limiting block with a guide groove connected end-to-end. The sliding column moves along the guide groove under the coordinated action of the compression block return spring and the displacement rod return spring. Mechanical limiting ensures precise control of the clamping opening and closing amount, realizing the conversion between the clamping assembly and the guard rod. This achieves automatic switching between two mechanical limiting states without external sensor intervention, eliminating manual adjustment, improving drill rod alignment accuracy and hole formation pass rate, and reducing cost and failure rate. Furthermore, by setting the elastic coefficients of the compression block return spring and the displacement rod return spring to have a difference, it ensures that the displacement rod can still accurately return to its initial position even under vibration, improving the anti-interference capability of this constraint assembly. This constraint assembly can be bolted or welded to existing clamping mechanisms, enabling disassembly and connection of this constraint assembly to existing clamping mechanisms that require manual adjustment of the clamping opening and closing amount, facilitating the modification of existing clamping mechanisms. Attached Figure Description

[0030] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0031] Figure 1 This is a schematic diagram of the structure of the clamping assembly according to the present invention in its initial position;

[0032] Figure 2 This is a schematic diagram of the clamping assembly according to the present invention when it is in the gripping rod position;

[0033] Figure 3 This is a schematic diagram of the structure of the clamping assembly according to the present invention when it is in the guard rod position;

[0034] Figure 4 This is an exploded view of the constraint assembly according to the present invention;

[0035] Figure 5 This is a simplified force diagram of the constraint component according to the present invention;

[0036] Figure 6 This is a schematic diagram of the structure of the second limiting block according to the present invention;

[0037] Figure 7 This is a flowchart illustrating the five states of the clamping assembly according to the present invention.

[0038] The components are as follows: 1. Support frame; 11. Drive component; 2. Clamping block; 21. Clamp; 3. Constraint assembly; 31. Bolt; 32. Cover plate; 33. First limiting block; 34. Main body; 35. Second limiting block; 351. Initial position; 352. Grab rod position; 353. Reset position; 354. Guard rod position; 355. Zero position; 356. Inner side wall; 357. Outer side wall; 36. Compression block reset spring; 37. Displacement rod; 371. Sliding column; 38. Pin; 39. Displacement rod reset spring; 310. Compression block; 311. Set screw. Detailed Implementation

[0039] The technical solutions of the embodiments of the present invention will be clearly and completely described 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 implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] It should be noted that the structures, proportions, sizes, etc., shown in the accompanying drawings of this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed in the specification, and are not intended to limit the conditions under which the present invention can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportional relationships, or adjustments to the size, without affecting the effects and objectives that the present invention can produce, should fall within the scope of the technical content disclosed in the present invention. It should be noted that in this specification, relational terms such as "first" and "second" are only used to distinguish one entity from several other entities, and do not necessarily require or imply any actual relationship or order between these entities.

[0041] Reference Figures 1 to 6 As shown, the present invention discloses a variable position clamping device, including a support frame 1, a clamping assembly and a constraint assembly 3.

[0042] Reference Figure 1 As shown, the support frame 1 is shaped like a "door" and has an installation groove inside. Four driving components 11 are installed in the installation groove. The four driving components 11 are symmetrically arranged on the two side walls of the installation groove. The drill bit clamping assembly is slidably installed in the installation groove. The drill bit clamping assembly includes two horizontally symmetrically arranged drill bit clamping blocks 2. Each of the two drill bit clamping blocks 2 has a chuck 21 for clamping the drill rod on one side opposite to the other side. The other side of the two drill bit clamping blocks 2 is connected to the driving component 11. The opposite driving component 11 drives the two drill bit clamping blocks 2 to move closer or further away.

[0043] Reference Figure 1 and Figure 4 As shown, the constraint assembly 3 is disposed between the opposite sides of the two clamping blocks 2. The constraint assembly 3 includes a main body 34, a displacement rod 37, and a compression block 310. The main body 34 is connected to the support frame 1. Specifically, the main body 34 is connected to the top of the mounting groove. The main body 34 has an internal accommodating space. A limiting block is provided in the main body 34 and is fixed thereto. A guide groove with its ends connected is provided in the limiting block. One end of the displacement rod 37 is hinged to the compression block 310 by a pin 38, and both ends of the pin 38 are connected to set screws 311. The set screws 311 are used to limit the position of the pin 38. The other end of the displacement rod 37 is provided with a sliding post 371, which is slidably embedded. Specifically, within the guide groove, the limiting block includes a first limiting block 33 and a second limiting block 35. The first limiting block 33 has a first groove, and the second limiting block 35 has a second groove. The first and second grooves are identical in shape, forming a closed guide groove. One end of the sliding column 371 is slidably embedded in the first groove, and the other end is slidably embedded in the second groove. The first and second grooves restrict the movement trajectory of the sliding column 371. When the driving member 11 drives the clamping block 2 to move, the clamping block 2 can drive the compression block 310 to move. The compression block 310 drives the displacement rod 37 to move, and the displacement rod 37 drives the sliding column 371 to move along the guide groove. (Refer to...) Figure 5As shown, a compression block return spring 36 is provided between the compression block 310 and the main body 34. The compression block 310 can move relative to the main body 34 in the axial direction of the compression block return spring 36. The compression block return spring 36 provides a return force to the compression block 310, so that the compression block 310 moving towards the inside of the main body 34 returns to its initial position to prepare for the next working process. A displacement rod return spring 39 is provided between the displacement rod 37 and the compression block 310. The displacement rod return spring 39 provides a return force to the displacement rod 37, thereby controlling the movement direction of the displacement rod 37. Of course, a cover plate 32 is also provided on the main body 34. The cover plate 32 is connected to the main body 34 by bolts 31, thereby ensuring the smooth movement of the compression block 310.

[0044] Among them, reference Figure 6 and Figure 7 As shown, the sliding trajectory of the sliding column 371 in the guide groove has an initial position 351, a grab bar position 352, a reset position 353, a guard bar position 354, and a zero position 355. The initial position 351 and the zero position 355 are on the same horizontal line and are both higher than the guard bar position 354. The guard bar position 354 is higher than the reset position 353, and the reset position 353 is higher than the grab bar position 352.

[0045] Continue to refer to Figure 6 As shown, the guide groove includes an inner wall 356 and an outer wall 357. The initial position 351 to the grab bar position 352 is the downward guide zone. When passing the grab bar position 352, the outer circumference of the sliding column 371 and the bottom inflection arc of the inner wall 356 are intersected. Tangent, the upward guide zone is from the lever position 352 to the zero position 355. For details, please refer to... Figure 1 As shown, when the two clamping blocks 2 open for the first time and the opening width is at its maximum, the sliding column 371 is in the initial position 351. At this time, the compression block 310 is not in contact with the clamping blocks 2, and the compression block return spring 36 and the displacement rod return spring 39 are in their natural length state; refer to Figure 2 As shown, when the two clamping blocks 2 close for the first time, and the opening and closing width between the two clamping blocks 2 is less than the drill pipe diameter, the sliding column 371 is in the gripping position 352. At this time, the compression block 310 is in contact with the clamping block 2, the compression block return spring 36 is in a compressed state, and the displacement rod return spring 39 is in a compressed state. When the two clamping blocks 2 open for the second time, the compression block return spring 36 is in a compressed state, and the compression block return spring 36 provides a force toward the compression block 310 to the displacement rod 37. The displacement rod return spring 39 is in a compressed state, and the displacement rod return spring 39 provides an upward force to the displacement rod 37. At this time, the sliding column 371 is restricted to the reset position 353 under the action of the compression block return spring 36 and the displacement rod return spring 39. Figure 3As shown, when the two clamping blocks 2 close for the second time, the clamping blocks 2 drive the compression block 310 to move. The compression block 310 and the compression block return spring 36 drive the displacement rod 37 to move. The displacement rod 37 drives the sliding column 371 to move along the guide groove to the guard rod position 354. At this time, the compression block return spring 36 is in a compressed state, and the displacement rod return spring 39 is in a compressed state. When the two clamping blocks 2 open for the third time, the compression block return spring 36 provides a force towards the compression block 310 to the displacement rod 37, and the displacement rod return spring 39 provides an upward force to the displacement rod 37. At this time, the sliding column 371 is at the zero position 355. At the zero position 355, the displacement rod return spring 39 is in its natural length state. That is to say, when the sliding column 371 reaches the zero position 355, the displacement rod... The return spring 39 is not under force. As the slide column 371 moves from the guard rod position 354 to the zero position 355, the compression block return spring 36 provides a force toward the compression block 310 to the displacement rod 37, and the displacement rod return spring 39 provides an upward force to the displacement rod 37. Since the elastic coefficient of the compression block return spring 36 is greater than that of the displacement rod return spring 39, that is, the force provided by the compression block return spring 36 toward the compression block 310 to the displacement rod 37 is greater than the upward force provided by the displacement rod return spring 39 to the displacement rod 37, the slide column 371 continues to move along the guide groove to the initial position 351. During the process of the slide column 371 moving from the zero position 355 to the initial position 351, the displacement rod return spring 39 provides a downward force to the displacement rod 37.

[0046] The downward guide zone includes a vertical section and an inclined section. The portion of the outer wall 357 located in the vertical section is aligned with the vertical centerline of the limiting block. Parallel, the outer wall 357 located in the inclined section faces the vertical centerline of the limiting block. Specifically, since the sliding column 371 relies solely on the compression block return spring 36 and the displacement rod return spring 39 for driving force during its movement from the zero position 355 to the initial position 351, the sliding column 371 requires sufficient movement space. This means the groove width in the vertical section must be greater than the groove width in other sections, and the portion of the outer wall 357 located in the vertical section must align with the vertical centerline of the limiting block. A parallel setting requires less effort compared to an inclined setting.

[0047] Continue to refer to Figure 6 As shown, the upward guide zone includes a first upward zone and a second upward zone. The first upward zone is from the grab bar position 352 to the reset position 353, and the second upward zone is from the guard bar position 354 to the zero position 355. When passing the reset position 353, the outer circumference of the sliding column 371 and the inner sidewall 356 are located at the top inflection point arc of the first upward zone. Tangent to each other, when passing the guardrail position 354, the outer circumference of the sliding column 371 and the outer side wall 357 are located at the bottom inflection point arc of the second upward zone. Tangent, the sliding column 371 passes through the center position of the circle at the reset position 353 to the vertical center line of the limit block. The horizontal distance is less than the distance from the center of the sliding column 371 at position 354 of the guard rod to the vertical center line of the limit block. The horizontal distance of the sliding column 371 from the zero position 355 through the top inflection point of the inner wall 356. After moving to the initial position 351, the portion of the inner wall 356 located in the downward guide area and the upward guide area both face the vertical centerline of the limiting block. Inclined, the portion of the outer wall 357 located in the upward guide area faces the vertical centerline of the limiting block. tilt.

[0048] As can be seen, this device, by setting a limiting block with a guide groove connected end to end, allows the sliding column 371 to move along the guide groove under the coordinated action of the compression block return spring 36 and the displacement rod return spring 39. Mechanical limiting ensures precise control of the clamping opening and closing amount, realizing the conversion of the clamping assembly from a guard rod to a gripping rod. That is, it achieves automatic switching between two mechanical limiting states without external sensor intervention, eliminating manual adjustment, improving the drill rod alignment accuracy and hole formation pass rate, reducing costs and failure rate. Furthermore, by setting the elastic coefficients of the compression block return spring 36 and the displacement rod return spring 39 to have a difference, it ensures that the sliding column 371 can still accurately return to the initial position 351 even in a vibration environment, improving the anti-interference capability of this constraint assembly 3. Moreover, this constraint assembly 3 can be connected to the existing clamping mechanism by bolts or welding, thus realizing the disassembly and connection of this constraint assembly 3 to the existing clamping mechanism, facilitating the modification of existing clamping mechanisms that require manual adjustment of the clamping opening and closing amount.

[0049] To ensure that the slide bar 371 can move stably along the guide groove, the width of the guide groove is 1.1 to 1.5 times the diameter of the slide bar 371.

[0050] Continue to refer to Figure 6 As shown, the horizontal distance from the center of the circle when the sliding rod 371 passes the initial position 351 to the center of the circle when the sliding rod 371 passes the grab bar position 352 is... The maximum displacement of the compression block 310 is the horizontal distance between the center position of the sliding column 371 when it passes the initial position 351 and the center position of the sliding column 371 when it passes the grab bar position 352. The horizontal distance between the center of the sliding column 371 when it passes the grab bar position 352 and the center of the sliding column 371 when it passes the guard bar position 354 is greater than twice the distance between the center of the sliding column 371 when it passes the grab bar position 352 and the center of the sliding column 371 when it passes the guard bar position 354. Specifically, when the drill pipe being gripped is a B22 drill pipe, the anchor bolt is generally a 20mm bolt. To ensure that both the drill pipe and the anchor bolt can be gripped at the grab position 352, the guard position 354 protects the drill pipe. The value is 5mm. It should be greater than 10mm.

[0051] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A variable-position clamping device, characterized in that, include: Support frame (1), with mounting grooves provided on the support frame (1); The drill bit clamping assembly is slidably disposed in the mounting groove. The drill bit clamping assembly includes two horizontally symmetrically arranged drill bit clamping blocks (2). Each of the two drill bit clamping blocks (2) has a chuck (21) for clamping the drill rod on one side opposite to the other side. A drive member (11) is provided between the other side of the two drill bit clamping blocks (2) and the support frame (1). The drive member (11) drives the drill bit clamping blocks (2) to reciprocate. The constraint component (3) is located between the opposite sides of the two clamping blocks (2). The constraint component (3) includes a main body (34), a displacement rod (37), and a compression block (310). The main body (34) is connected to the support frame (1). A limiting block is fixed to the main body (34). A guide groove with the ends connected is provided in the limiting block. One end of the displacement rod (37) is connected to the compression block (310). The other end of the displacement rod (37) is provided with a sliding column (371). The sliding column (371) is slidably embedded in the guide groove. The clamping blocks (2) drive the compression block (310) to move. The compression block (310) drives the displacement rod (37) to move, and the displacement rod (37) drives the sliding column (371) to move along the guide groove. A compression block return spring (36) is provided between the compression block (310) and the main body (34). The compression block (310) can move relative to the main body (34) in the axial direction of the compression block return spring (36). The compression block return spring (36) provides a return force to the compression block (310). A displacement rod return spring (39) is provided between the displacement rod (37) and the compression block (310). The displacement rod return spring (39) provides a return force to the displacement rod (37). The spring constant of the compression block return spring (36) is greater than that of the displacement rod return spring (39); Among them, the sliding trajectory of the sliding column (371) in the guide groove has an initial position (351), a grab bar position (352), a reset position (353), a guard bar position (354) and a zero position (355). The initial position (351) and the zero position (355) are on the same horizontal line and are both higher than the guard bar position (354). The guard bar position (354) is higher than the reset position (353), and the reset position (353) is higher than the grab bar position (352).

2. The variable position clamping device according to claim 1, characterized in that, The limiting block includes a first limiting block (33) and a second limiting block (35). The first limiting block (33) has a first groove, and the second limiting block (35) has a second groove. The first groove and the second groove are the same shape, forming a closed guide groove. One end of the sliding column (371) is slidably embedded in the first groove, and the other end is slidably embedded in the second groove.

3. The variable position clamping device according to claim 1, characterized in that, The width of the guide groove is 1.1 to 1.5 times the diameter of the sliding column (371).

4. The variable position clamping device according to claim 1, characterized in that, The horizontal distance from the center of the slide bar (371) when it passes the initial position (351) to the center of the slide bar (371) when it passes the grab bar position (352) is the maximum displacement of the compression block (310). The horizontal distance from the center of the slide bar (371) when it passes the initial position (351) to the center of the slide bar (371) when it passes the grab bar position (352) is greater than twice the horizontal distance from the center of the slide bar (371) when it passes the grab bar position (352) to the center of the slide bar (371) when it passes the guard bar position (354).

5. A variable position clamping device according to any one of claims 2 to 4, characterized in that, The guide groove includes an inner wall (356) and an outer wall (357); The initial position (351) to the gripper position (352) is the downward guide zone. When passing the gripper position (352), the outer circumference of the sliding column (371) is tangent to the bottom inflection arc of the inner sidewall (356); When the two clamping blocks (2) open for the first time and the opening and closing width is the largest, the sliding column (371) is in the initial position (351). At this time, the compression block (310) separates from the clamping block (2), and the compression block return spring (36) and the displacement rod return spring (39) are in the natural length state. When the two clamping blocks (2) close for the first time, and the opening and closing width between the two clamping blocks (2) is less than the diameter of the drill rod, the sliding rod (371) is in the gripping rod position (352). At this time, the compression block (310) is in contact with the clamping block (2), the compression block return spring (36) is in a compressed state, and the displacement rod return spring (39) is in a compressed state.

6. A variable position clamping device according to claim 5, characterized in that, The downward guide zone includes a vertical section and an inclined section. The portion of the outer wall (357) in the vertical section is parallel to the vertical center line of the limiting block, while the portion of the outer wall (357) in the inclined section is inclined toward the vertical center line of the limiting block.

7. A variable position clamping device according to claim 6, characterized in that, The area from the lever position (352) to the zero position (355) is the upward guide zone; The upward guide area includes a first upward area and a second upward area. The first upward area is from the gripper position (352) to the reset position (353), and the second upward area is from the guard rod position (354) to the zero position (355). When passing the reset position (353), the outer circumference of the slide column (371) is tangent to the arc of the top inflection point of the inner wall (356) in the first upward area. When passing the guard rod position (354), the outer circumference of the slide column (371) is tangent to the arc of the bottom inflection point of the outer wall (357) in the second upward area. The horizontal distance from the center position of the slide column (371) when passing the reset position (353) to the vertical center line of the limit block is less than the horizontal distance from the center position of the slide column (371) when passing the guard rod position (354) to the vertical center line of the limit block. The sliding column (371) moves from the zero position (355) through the top inflection point of the inner wall (356) to the initial position (351). The inner wall (356) located in the downward guide area and the upward guide area are inclined toward the vertical center line of the limiting block, and the outer wall (357) located in the upward guide area is inclined toward the vertical center line of the limiting block.

8. A variable position clamping device according to claim 7, characterized in that, When the two clamping blocks (2) open for the second time, the compression block return spring (36) is in a compressed state, and the compression block return spring (36) provides a force toward the compression block (310) to the displacement rod (37). The displacement rod return spring (39) is in a compressed state, and the displacement rod return spring (39) provides an upward force to the displacement rod (37). At this time, the sliding rod (371) is in the reset position (353). When the two clamping blocks (2) close for the second time, the clamping blocks (2) drive the compression block (310) to move. The compression block (310) and the compression block return spring (36) drive the displacement rod (37) to move. The displacement rod (37) drives the slide column (371) to move along the guide groove to the guard rod position (354). At this time, the compression block return spring (36) is in a compressed state, and the displacement rod return spring (39) is in a compressed state. When the two clamping blocks (2) open for the third time, the compression block return spring (36) provides a force toward the compression block (310) to the displacement rod (37). The compression block return spring (36) is in a compressed state, and the displacement rod return spring (39) provides an upward force to the displacement rod (37). At this time, the sliding column (371) is in the zero position (355), and the displacement rod return spring (39) is in its natural length state.

9. A variable position clamping device according to claim 8, characterized in that, When the slide bar (371) moves from the zero position (355) to the initial position (351), the compression block return spring (36) provides a force toward the compression block (310) to the displacement rod (37), and the displacement rod return spring (39) provides a downward force to the displacement rod (37).

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