CN113458917B

CN113458917B - Accurate guidance steering wheel shell anchor clamps of polishing

Info

Publication number: CN113458917B
Application number: CN202111037501.3A
Authority: CN
Inventors: 雷声洪; 卢小玲
Original assignee: Chengdu Zhili Technology Development Co ltd
Current assignee: Chengdu Zhili Technology Development Co ltd
Priority date: 2021-09-06
Filing date: 2021-09-06
Publication date: 2021-11-16
Anticipated expiration: 2041-09-06
Also published as: CN113458917A

Abstract

The application provides an accurate guidance steering wheel shell anchor clamps of polishing includes: a mandrel and a connecting block; the mandrel penetrates through the connecting block, and the relative positions of the connecting block and the mandrel along the circumference are kept fixed; the rear end of the mandrel is used for connecting a machine tool. The front section of the mandrel penetrates into the main shell from the front end of the main shell of the steering engine; the connecting block is positioned in the second seat hole of the main shell, and the outer wall of the connecting block is attached to the inner wall of the second seat hole; the position of the mandrel, which corresponds to the conical hole of the main shell, is provided with a conical frustum, and the conical frustum is matched with the conical hole; the inclined hole of the main shell body is provided with a screw in a penetrating way and used for connecting the core shaft. The connecting block periphery is equipped with positioning screw, and positioning screw passes the through hole of installing in main casing body upper cover plate. The integral grinding processing of the steering engine shell can be finished by one-time clamping, so that the grinding quality can be effectively improved, and the shape precision of the steering engine shell can be ensured; meanwhile, the deformation of the shell of the steering engine can be avoided, and the yield is improved, so that the cost is reduced.

Description

Accurate guidance steering wheel shell anchor clamps of polishing

Technical Field

The invention belongs to a steering engine production and processing technology used in the field of accurate guidance, and particularly relates to a polishing clamp for an accurate guidance steering engine shell.

Background

The steering engine is widely applied in the field of accurate guidance, and the requirement on the aspects of guidance accuracy flight stability and the like is very strict due to the accurate guidance, so that the requirement on the processing quality of a steering engine shell for accurate guidance is very high. As shown in fig. 6 and 7, the steering engine housing mainly includes a main housing, a base, and a plurality of cover plates, and in order to improve the overall processing quality of the outer wall of the steering engine housing, the main housing, the base, and the cover plates are generally required to be integrally polished after being assembled. Because the whole steering wheel shell is tubular structure, and is the thin wall part, the very clamping of being not convenient for. The existing clamping mode usually utilizes copper foil or gauze to wrap the outer wall of a steering engine shell, then a clamping jaw of a machine tool is used for clamping, one end of the steering engine shell is firstly processed, and then the other end of the steering engine shell is processed. However, in this way, clamping is performed twice, so that the polishing reference cannot be completely unified, and the final polishing precision is very affected. On the other hand, the mode that the jack catch directly clamps the steering engine shell easily leads to the steering engine shell to warp, finally leads to scrapping, increases the cost of manufacture.

Disclosure of Invention

In order to solve the defects of the prior art, the invention provides the precise guidance steering engine shell polishing clamp, the overall polishing of the steering engine shell can be finished by one-time clamping, the processing reference is ensured, the polishing quality is improved, and the shape precision of the steering engine shell is ensured; the steering engine shell is clamped through the inside, so that the deformation of the steering engine shell is avoided, the yield is improved, and the cost is reduced.

In order to realize the purpose of the invention, the following scheme is adopted:

a grinding clamp for an accurate guidance steering engine shell comprises a main shell of a cylindrical structure and a base arranged at the rear end of the main shell; a first seat hole, a second seat hole and a through hole are sequentially formed in the main shell from back to front, a conical hole is formed in the front end of the through hole, a plurality of inclined holes are formed in the front section of the main shell along the circumference, and the inclined holes are perpendicular to the side wall of the conical hole; the main casing body is evenly provided with four cover plates corresponding to the circumference of the second seat hole section, and the cover plates are provided with through holes for penetrating through the rudder shaft.

The clamp includes: a mandrel and a connecting block; the mandrel penetrates through the connecting block, and the relative positions of the connecting block and the mandrel along the circumference are kept fixed; the rear end of the mandrel is used for connecting a machine tool.

The front section of the mandrel penetrates into the main shell from the front end of the main shell; the connecting block is positioned in the second seat hole, and the outer wall of the connecting block is attached to the inner wall of the second seat hole; a cone frustum is arranged at the position of the mandrel corresponding to the cone hole and matched with the cone hole; the inclined hole is provided with a screw for connecting the core shaft.

The periphery of the connecting block is provided with a positioning screw rod which passes through the through hole of the cover plate.

Furthermore, second seat hole cross-section is rectangular hole structure, and corresponding connecting block is rectangle block structure, and during the use, the apron is installed behind the main casing body, and the bottom surface of apron and the outer wall contact of connecting block.

Furthermore, the bottom of a threaded hole for penetrating a positioning screw rod of the connecting block is provided with a positioning hole, the front end of the positioning screw rod is provided with a positioning rod, and the positioning rod penetrates through the positioning hole; the head of the positioning screw rod is positioned in the through hole; the head of the positioning screw rod is of an arc-shaped structure and is positioned in the main shell.

Further, the outer wall of dabber has the keyway along the axis processing in opposite directions, and the inside key that is equipped with of connecting block, key and keyway sliding fit, key are the cylinder structure, and the cross-section of keyway is semi-circular structure.

Furthermore, the rear end of the mandrel is provided with a limiting disc for limiting the connecting position of the machine tool clamping jaw and the mandrel, and a gap is formed between the limiting disc and the front end face of the main shell.

Furthermore, the device also comprises a limiting block, wherein the limiting block is arranged at the front end of the mandrel; during the use, the stopper is located first seat downthehole, and stopper outer wall and the laminating of first seat downthehole wall.

Further, the stopper passes through locking screw to be connected in the front end of dabber, and first seat hole inner wall has the sand grip, and the stopper outer wall corresponds the sand grip and sets up flutedly, recess and sand grip cooperation, and the stopper adopts the rubber materials preparation, is extrusion contact between stopper and the first seat hole inner wall to eliminate clearance each other.

Furthermore, a circular ring is arranged on one side of the limiting block, which is positioned on the base, and the circular ring is connected with the limiting block through a spring; when the device is used, the base is in contact with the circular ring, and the spring is in a compressed state.

Furthermore, a plurality of counter bores are uniformly formed in the limiting block along the circumference.

The invention has the beneficial effects that:

1. utilize dabber and connecting block to carry out the centre gripping to the steering wheel shell to utilize the dabber to replace the jack catch of steering wheel shell and lathe to link to each other, a clamping can accomplish the whole processing of polishing to the steering wheel shell, has guaranteed the unity of the benchmark of processing, greatly improves the quality of polishing, guarantees the shape precision of steering wheel shell simultaneously.

2. Through dabber, connecting block and stopper, carry out the centre gripping to the steering wheel shell from inside, avoid the steering wheel shell to warp, improve the yield to reduce cost. But also provides good support for the cover plate part by utilizing the connecting block, and prevents the cover plate from deforming.

3. Because steering wheel shell is tubular structure, the position that usually keeps away from the clamping end is farther, and when the rotation was polished, vibration amplitude is also bigger. In order to reduce the vibration amplitude of the rear end of the steering engine shell, a limiting block is specially arranged, the connecting rigidity between the rear end of the main shell and the mandrel is enhanced by the limiting block, so that the vibration amplitude of the rear end of the steering engine shell is reduced, and the polishing quality and the shape precision of the steering engine shell are further improved.

4. A plurality of connecting structures are arranged between the main shell and the mandrel, and more stable relative position structures are arranged between the main shell and the mandrel, so that the shaking of the steering engine shell in the polishing process is reduced, and the polishing quality is improved.

Drawings

The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.

Fig. 1 shows a constitutional diagram of the present application.

Figure 2 shows a cross-sectional view of the connecting block when connected to the mandrel.

Fig. 3 shows a block diagram of the clamping of the steering engine housing.

Fig. 4 shows an overall cross-sectional view of the steering engine housing in its clamped position.

Fig. 5 shows an enlarged view at a in fig. 4.

Fig. 6 shows a connection state diagram of the steering engine housing and the clamp.

Fig. 7 shows an internal structure view of a steering engine housing.

The labels in the figure are: the device comprises a main shell body-1, a first seat hole-11, a convex strip-111, a second seat hole-12, a through hole-13, a conical hole-14, an inclined hole-15, a base-2, a cover plate-3, a through hole-31, a mandrel-4, a conical frustum-41, a key groove-42, a limiting disc-43, a connecting block-5, a positioning hole-51, a key-52, a limiting block-6, a groove-61, a counter bore-62, a positioning screw rod-7, a positioning rod-71, a locking screw-8, a circular ring-9 and a spring-91.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the following detailed description of the embodiments of the present invention is provided with reference to the accompanying drawings, but the described embodiments of the present invention are a part of the embodiments of the present invention, not all of the embodiments of the present invention.

It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.

In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings or orientations or positional relationships that the products of the present invention are usually placed in when used, and are only for convenience of describing the present invention and simplifying the description. The terms "first," "second," and the like are used solely to distinguish one from another and are not to be construed as indicating or implying relative importance. The terms "parallel", "perpendicular", etc. do not require that the components be absolutely parallel or perpendicular, but may be slightly inclined.

In the description of the present invention, it should also be noted that, unless otherwise explicitly specified or limited, the terms "disposed," "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; either directly or indirectly through intervening media, or through both elements. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

Example 1

As shown in fig. 1 and 2, the grinding clamp for the shell of the precision guidance steering engine comprises: a mandrel 4 and a connecting block 5; the mandrel 4 penetrates through the connecting block 5, the relative positions of the connecting block 5 and the mandrel 4 along the circumference are kept fixed, and the connecting block 5 can slide along the axis of the mandrel 4 but cannot rotate around the axis of the mandrel 4; the rear end of the mandrel 4 is used for connecting a machine tool.

As shown in fig. 6 and 7, the steering engine housing clamped by the clamp of the present application includes a main housing 1 having a cylindrical structure and a base 2 disposed at the rear end of the main housing 1. A first seat hole 11, a second seat hole 12 and a through hole 13 are sequentially formed in the main shell 1 from back to front, a conical hole 14 is formed in the front end of the through hole 13, a plurality of inclined holes 15 are formed in the front section of the main shell 1 along the circumference, and the inclined holes 15 are perpendicular to the side wall of the conical hole 14; the main casing 1 corresponds the circumference of the 12 sections of second seat hole and evenly is equipped with four apron 3, and apron 3 has through hole 31 for wear to establish the rudder axle.

Specifically, as shown in fig. 3 and 4, in use, the front section of the spindle 4 penetrates into the main housing 1 from the front end of the main housing 1. The connecting block 5 is positioned in the second seat hole 12, and the outer wall of the connecting block 5 is attached to the inner wall of the second seat hole 12. The position of the mandrel 4 corresponding to the conical hole 14 is provided with a conical frustum 41, and the conical frustum 41 is matched with the conical hole 14 so as to improve the coaxiality of the mandrel 4 and the main shell 1, thereby ensuring the cylindricity of the shell of the steering engine after polishing and preventing eccentricity. The inclined hole 15 is provided with a screw for connecting the mandrel 4, so that the main housing 1 and the mandrel 4 are connected for the first time.

Specifically, as shown in fig. 1, fig. 2 and fig. 5, a positioning screw 7 is disposed on the periphery of the connecting block 5, the positioning screw 7 penetrates through a through hole 31 of the cover plate 3, the positioning screw 7 is used to keep the relative positions between the connecting block 5 and the cover plate 3 as well as between the connecting block and the mandrel 4 fixed, the front ends of the positioning screws 7 are pressed against the outer wall of the mandrel 4, and the distances between the front ends of all the positioning screws 7 and the axis of the mandrel 4 are the same, so as to ensure that the mandrel 4 and the connecting block 5 are coaxial, thereby ensuring that the connecting block 5 is coaxial with the main housing 1, and making the distances between the outer wall of the connecting block 5 and the bottom surface of the cover plate 3 the same.

Preferably, as shown in fig. 1, 2 and 5, the cross section of the second seat hole 12 is a rectangular hole structure, the corresponding connecting block 5 is a rectangular block structure, and the connecting block 5 is matched with the rectangular hole through the rectangular block to prevent the connecting block 5 from rotating relative to the main casing 1, when in use, after the cover plate 3 is installed on the main casing 1, the bottom surface of the cover plate 3 is in contact with the outer wall of the connecting block 5, so as to facilitate the installation of the connecting block 5, therefore, the connecting block 5 is in clearance fit with the second seat hole 12, and a relative rotation gap exists, and the cover plate 3 is used for further pressing the connecting block 5 to eliminate the clearance influence between the connecting block 5 and the second seat hole 12 and prevent the connecting block 5 from rotating relative to the main casing 1; also utilize connecting block 5 to support apron 3 simultaneously, improve apron 3's stress intensity, apron 3 takes place to warp when preventing to polish.

Preferably, as shown in fig. 2 and 5, the connecting block 5 has a positioning hole 51 at the bottom of the threaded hole for passing the positioning screw 7, the positioning screw 7 has a positioning rod 71 at the front end thereof, and the positioning rod 71 passes through the positioning hole 51. The matching precision between the positioning rod 71 and the positioning hole 51 is higher than that of the threaded connection between the positioning screw 7 and the connecting block 5, so that the gap of the threaded connection between the positioning screw 7 and the connecting block 5 is eliminated, and the stability of the relative position of the positioning screw 7 and the connecting block 5 is improved. Further preventing the connecting block 5 from being displaced relative to the positioning screw 7. The head of the positioning screw rod 7 is positioned in the through hole 31 so as to improve the stability of the relative position between the cover plate 3 and the positioning screw rod 7, improve the stability of the relative position between the cover plate 3 and the connecting block 5 through the positioning screw rod 7, further improve the stability of the relative position between the cover plate 3, the connecting block 5 and the mandrel 4, prevent the polishing, lead to vibration due to relative movement, and improve the stability during integral rotation.

Further preferably, as shown in fig. 2 and 5, the head of the positioning screw rod 7 is in an arc-shaped structure, and the head of the positioning screw rod 7 is still in the main housing 1 after the steering engine housing is ground, so that the heads of the positioning screw rod 7 are prevented from being ground together during grinding.

Preferably, as shown in fig. 1 and 2, the outer wall of the mandrel 4 is processed with key grooves 42 along the axis in opposite directions, a key 52 is arranged inside the connecting block 5, the key 52 is in sliding fit with the key grooves 42 to prevent the connecting block 5 from rotating relative to the mandrel 4, the key 52 is of a cylindrical structure, the cross section of each key groove 42 is of a semicircular structure, and compared with the conventional key groove with a rectangular cross section, the rectangular structure is reduced, stress concentration is avoided, and therefore the structural strength of the mandrel 4 is improved.

Preferably, as shown in fig. 1, 3 and 6, a limiting disc 43 is arranged at the rear end of the spindle 4 and used for limiting the connection position of the jaws of the machine tool and the spindle 4, and a gap is formed between the limiting disc 43 and the front end surface of the main housing 1 to play a role of an overrun groove of a grinding wheel, so that the grinding wheel can completely cover the main housing 1, meanwhile, the limiting disc 43 is also used for preventing the distance between the jaws of the machine tool and the main housing 1 from being too small, the clamping position of the jaws on the spindle 4 can be directly determined through the limiting disc 43, repeated adjustment is avoided, and the clamping efficiency of the machine tool on the clamp is improved.

Example 2

As shown in fig. 1 and 3, the precise guidance steering engine shell grinding clamp further comprises a limiting block 6, and the limiting block 6 is arranged at the front end of the mandrel 4; when the steering engine is used, the limiting block 6 is positioned in the first seat hole 11, the outer wall of the limiting block 6 is attached to the inner wall of the first seat hole 11, and the steering engine shell is of a long-tube-shaped structure and is far away from one end clamped by a machine tool, so that the swinging amplitude is large during rotation, and the shape precision of the polished steering engine shell is seriously influenced; the rear end of the steering engine shell is supported by the mandrel 4 through the limiting block 6, so that the stability of interconnection between the mandrel 4 and the steering engine shell is improved, the swing amplitude of the rear end of the steering engine shell is reduced, and the processing quality is improved.

Preferably, as shown in fig. 1, 3 and 7, the stopper 6 is connected to the front end of the core shaft 4 by a locking screw 8, the inner wall of the first seat hole 11 has a plurality of ribs 111, the plurality of ribs 111 are uniformly arranged along the circumference, and the extending direction of the ribs 111 is the same as the axial direction of the main housing 1. The 6 outer walls of stopper correspond sand grip 111 and have seted up recess 61, and recess 61 cooperates with sand grip 111 to prevent to take place relative rotation between stopper 6 and the main casing body 1.

Further preferably, stopper 6 adopts the rubber materials preparation, utilizes rubber materials can be compressed and have elastic characteristic, makes to be extrusion contact between stopper 6 and the 11 inner walls of first seat hole to eliminate clearance each other, and rubber materials is lighter than the metal material quality, effectively reduces the weight of centre gripping rear steering wheel shell rear end, further reduces the amplitude of oscillation of steering wheel shell rear end.

Preferably, as shown in fig. 1 and 6, a circular ring 9 is arranged on one side of the limiting block 6, which is located on the base 2, the circular ring 9 is connected with the limiting block 6 through a spring 91, and a locking screw 8 penetrates through the circular ring 9 and the spring 91; when in use, the base 2 is in contact with the ring 9, and the spring 91 is in a compressed state; after the base 2 is mounted on the main housing 1, the spring 91 is compressed, so that the outer periphery of the limiting block 6 is pressed, and the peripheral side of the limiting block 6 is further pressed against the inner wall of the first seat hole 11; meanwhile, when the steering engine shell rotates at a high speed, the deformation of the limiting block 6 can be reduced by utilizing the pressure exerted by the spring 91, so that the structure of the steering engine shell is more stable, and the characteristics are favorable for improving the polishing quality of the steering engine shell.

Preferably, as shown in fig. 3 and 4, the limiting block 6 is uniformly provided with a plurality of counter bores 62 along the circumference, so that the weight of the limiting block 6 is further reduced, the overall weight of the rear end of the steering engine shell during polishing is reduced, the swinging amplitude of the rear end of the steering engine shell is reduced, and the polishing quality of the steering engine shell is improved.

The specific implementation mode is as follows: during clamping, the spindle 4 is inserted into the main housing 1 from one end of the through hole 13, and the main housing 1 is fixed to the spindle 4 by screws through the inclined holes 15. The connection block 5 is inserted from the rear end of the main housing 1 such that the connection block 5 is located at the installation position of the cover plate 3.

Installing cover plate 3, utilizing cover plate 3 to fix connecting block 5 in advance, installing positioning screw 7 makes the position between connecting block 5 and dabber 4 fixed, then screws up the mounting screw of cover plate 3 completely, utilizes cover plate 3 to carry out final fixed with connecting block 5 to guaranteed the stability of relative position between cover plate 3, dabber 4 and the connecting block 5, also borrow this to make main casing body 1 and dabber 4 realize that the second is said and be connected.

And installing a limiting block 6, drawing the limiting block 6 into the first seat hole 11 through a locking screw 8, and connecting the limiting block 6 to the core shaft 4 by using the locking screw 8. Make the rear end relative position of dabber 4 and main casing body 1 more stable through stopper 6 to realize the third between main casing body 1 and the dabber 4 and be connected. Finally, the base 2 is installed. When polishing, the clamping jaw of the machine tool is used for clamping the rear end of the mandrel 4.

The foregoing is only a preferred embodiment of the present invention and is not intended to be exhaustive or to limit the invention. It will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the scope of the invention.

Claims

1. A grinding clamp for an accurate guidance steering engine shell comprises a main shell (1) in a cylindrical structure and a base (2) arranged at the rear end of the main shell (1); a first seat hole (11), a second seat hole (12) and a through hole (13) are sequentially formed in the main shell (1) from back to front, a conical hole (14) is formed in the front end of the through hole (13), a plurality of inclined holes (15) are formed in the front section of the main shell (1) along the circumference, and the inclined holes (15) are perpendicular to the side wall of the conical hole (14); four cover plates (3) are uniformly arranged on the main shell (1) corresponding to the circumference of the section of the second seat hole (12), and the cover plates (3) are provided with through holes (31) for penetrating through a rudder shaft; its characterized in that, anchor clamps of polishing include: a mandrel (4) and a connecting block (5); the mandrel (4) penetrates through the connecting block (5), and the relative positions of the connecting block (5) and the mandrel (4) along the circumference are kept fixed; the rear end of the mandrel (4) is used for connecting a machine tool;

the front section of the mandrel (4) is used for penetrating into the main shell (1) from the front end of the main shell (1); the connecting block (5) is positioned in the second seat hole (12), and the outer wall of the connecting block (5) is attached to the inner wall of the second seat hole (12); a conical frustum (41) is arranged at the position of the mandrel (4) corresponding to the conical hole (14), and the conical frustum (41) is matched with the conical hole (14); a screw is arranged in the inclined hole (15) in a penetrating way and is used for connecting the core shaft (4);

a positioning screw rod (7) is arranged on the periphery of the connecting block (5), and the positioning screw rod (7) penetrates through a through hole (31) of the cover plate (3);

the outer wall of dabber (4) is processed along the axis in opposite directions has keyway (42), and connecting block (5) are inside to be equipped with key (52), key (52) and keyway (42) sliding fit, and key (52) are the cylinder structure, and the cross-section of keyway (42) is semicircular structure.

2. The grinding clamp for the shell of the precise-guidance steering engine according to claim 1, wherein the section of the second seat hole (12) is in a rectangular hole structure, and the corresponding connecting block (5) is in a rectangular block structure; the cover plate (3) is arranged behind the main shell (1), and the bottom surface of the cover plate (3) is in contact with the outer wall of the connecting block (5).

3. The grinding clamp for the shell of the precise-guidance steering engine according to claim 1, wherein a positioning hole (51) is formed in the bottom of a threaded hole for the positioning screw (7) to penetrate through in the connecting block (5), a positioning rod (71) is arranged at the front end of the positioning screw (7), and the positioning rod (71) penetrates through the positioning hole (51); the head of the positioning screw rod (7) is positioned in the through hole (31); the head of the positioning screw rod (7) is of an arc-shaped structure, and when the positioning screw rod is used, the head of the positioning screw rod (7) is positioned in the main shell (1).

4. The grinding clamp for the shell of the precise-guidance steering engine according to claim 1, wherein a limiting disc (43) is arranged at the rear end of the mandrel (4) and used for limiting the connecting position of a machine tool jaw and the mandrel (4), and a gap is formed between the limiting disc (43) and the front end face of the main shell (1) in use.

5. The grinding clamp for the shell of the accurate-guidance steering engine according to claim 1, characterized by further comprising a limiting block (6), wherein the limiting block (6) is arranged at the front end of the mandrel (4); during the use, stopper (6) are located first seat hole (11), and stopper (6) outer wall and the laminating of first seat hole (11) inner wall.

6. The grinding clamp for the shell of the accurate-guidance steering engine according to claim 5, wherein the limiting block (6) is connected to the front end of the mandrel (4) through a locking screw (8), a protruding strip (111) is arranged on the inner wall of the first seat hole (11), a groove (61) is formed in the outer wall of the limiting block (6) corresponding to the protruding strip (111), the groove (61) is used for being matched with the protruding strip (111), the limiting block (6) is made of a rubber material, and when the grinding clamp is used, the limiting block (6) is in extrusion contact with the inner wall of the first seat hole (11) so as to eliminate a gap between the limiting block (6) and the inner wall of the first seat hole (11).

7. The grinding clamp for the shell of the accurate-guidance steering engine according to claim 5, wherein a circular ring (9) is arranged on one side, located on the base (2), of the limiting block (6), and the circular ring (9) is connected with the limiting block (6) through a spring (91); when in use, the base (2) is contacted with the circular ring (9), and the spring (91) is in a compressed state.

8. The precise-guidance steering engine shell grinding clamp as claimed in claim 5, wherein the limiting block (6) is uniformly provided with a plurality of counter bores (62) along the circumference.