CN215788358U

CN215788358U - Clamping device for medium and large complex pitched roof

Info

Publication number: CN215788358U
Application number: CN202122295885.0U
Authority: CN
Inventors: 孙柏林; 罗昕雨; 秦云凡; 王巍; 邓伟; 程宝欣
Original assignee: Chengdu Aerospace Mould&plastics Co ltd Chengdu Mould Branch
Current assignee: Chengdu Aerospace Mould&plastics Co ltd Chengdu Mould Branch
Priority date: 2021-09-18
Filing date: 2021-09-18
Publication date: 2022-02-11
Anticipated expiration: 2031-09-18

Abstract

The utility model discloses a clamping device for a medium and large complex lifter, and relates to the technical field of clamping tools; the clamping device comprises a base, a fixed seat and a movable seat, wherein the fixed seat and the movable seat are oppositely arranged at two ends of the base; an adjusting guide rail is arranged on the base, the adjusting guide rail extends from the movable seat to the fixed seat, and the movable seat is connected to the adjusting guide rail in a sliding manner; the movable seat is provided with a jacking mechanism, and one end of the jacking mechanism facing the locking mechanism is provided with a jacking end so as to be capable of jacking and fixing a workpiece through the locking mechanism and the jacking end; through implementing this technical scheme, can effectively solve the big technical problem of the current oblique top clamping alignment degree of difficulty, simple structure and installation are convenient, can follow oblique top side clamping, are applicable to the quick clamping of the complicated oblique top of well large-size shape/mold insert, can effectively improve machining efficiency.

Description

Clamping device for medium and large complex pitched roof

Technical Field

The utility model relates to the technical field of clamping tools, in particular to a clamping device for a large and medium-sized complex pitched roof.

Background

The lifter is a common part in an automotive interior part die, a conventional middle-large complex lifter shown in figure 5 has the three reverse buckling areas of A/B/C, clamping surfaces need to be designed for the three areas in advance in the machining process, a plane opposite to the locking plate is machined for the three areas by taking the locking plate as an example, drilled screw holes are reserved, clamping positions are reserved for opening the thick back front side respectively, the three areas are machined by clamping for three times after the thick back side and the front side are machined.

The existing inclined top processing and clamping mode at least has the following defects: firstly, at least 10 times of clamping are needed for processing three areas of the same lifter, the operation is complex and the processing efficiency is low; secondly, as clamping positions are reserved for the inclination area, the processing stress effect is not ideal; when the front face is machined, the back face area cannot be locked, an adding equal-height welding clamping mode is needed, four sides of the material ordering size of the clamping mode need to be increased to form a machining area, the clamping alignment difficulty is high every time, the precision completely depends on the meter calibration level of an operator, accumulated errors are accumulated in reprocessing because the meter calibration difficulty is very high every time, the precision cannot be basically guaranteed, and the product quality and the machining efficiency are seriously influenced.

SUMMERY OF THE UTILITY MODEL

Aiming at the technical problems, the utility model aims to provide a clamping device for a middle-large complex lifter, which can effectively solve the technical problem of high alignment difficulty of the existing lifter clamping, has a simple structure, is convenient to install, can clamp from the side surface of the lifter, is suitable for quick clamping of the middle-large complex lifter/insert and can effectively improve the processing efficiency.

The technical scheme adopted by the utility model is as follows:

a clamping device for middle and large complex pitched roof comprises a base, a fixed seat and a movable seat, wherein the fixed seat and the movable seat are oppositely arranged at two ends of the base, and the fixed seat and the movable seat are respectively provided with a groove for accommodating a spring

The fixed seat is fixed on the base, a rotating column and a positioning hole for the rotating column to pass through are arranged on the fixed seat, a locking mechanism is arranged at one end of the rotating column facing the movable seat, and a locking piece used for fixing the rotating column on the fixed seat is arranged at the other end of the rotating column;

an adjusting guide rail is arranged on the base, extends from the movable seat to the fixed seat, and is connected to the adjusting guide rail in a sliding manner;

the movable seat is provided with a jacking mechanism, and a jacking end is arranged at one end of the jacking mechanism facing the locking mechanism so as to jack and fix a workpiece through the locking mechanism and the jacking end.

Preferably, in the above technical scheme, a radially protruding positioning step is arranged in the positioning hole, a plurality of axially extending positioning grooves are arranged on the positioning step at intervals, a radially recessed positioning surface is arranged at a position where the rotary column extends into the positioning hole, a plurality of axially extending positioning protrusions are uniformly arranged on the positioning surface, and the positioning protrusions can be engaged with the positioning grooves, so that the rotary column can pass through the positioning hole to realize radial positioning; according to the technical scheme, the rotating column can rotate in the positioning hole to adjust the angle of the locking mechanism, so that the workpiece clamping precision is guaranteed, the positioning groove formed in the positioning step in the positioning hole is meshed with the positioning boss on the rotating column, and the rotating column can be prevented from radially rotating after being fixed by the locking piece, so that the workpiece clamping and machining precision is further guaranteed.

Preferably, in the above technical solution, a rotary scale mark is arranged on a side surface of the fixed seat, the rotary scale mark is uniformly arranged on the outer side of the rotary column with the axis of the rotary column as a center, and a guide matched with the rotary scale mark is arranged on the rotary column; so can effectively guarantee the positioning accuracy of column spinner, this technical scheme clamping device can directly fix a position the work piece through locking mechanism after adjusting the column spinner location angle, avoids proofreading and alignment repeatedly and has the big technical problem of the alignment degree of difficulty, and the work piece clamping accuracy is controlled by the device, and the precision can effectively be ensured.

Preferably, in the above technical solution, the adjusting guide rail is disposed below a top plane of the base, a connecting block is disposed at the bottom of the movable seat, and a lower end of the connecting block can be embedded into the adjusting guide rail and slide along the adjusting guide rail; so can effectively guarantee the smooth stability of connecting block slip on adjusting the guide rail, and the movable block constitutes its bearing capacity with the connecting block and can effectively guarantee with the connecting block for the tight mechanism in top is fixed stable to the work piece.

Preferably, in the technical scheme, strip-shaped holes are formed in the connecting block on two sides along the sliding direction of the movable seat, a plurality of locking holes are formed in the base along the sliding direction of the movable seat, connecting pieces are arranged in the strip-shaped holes, and the connecting pieces can penetrate through the strip-shaped holes and the locking holes to fix the connecting block; this technical scheme has adjusted the fixed position of sliding seat earlier before the clamping work piece, removes the sliding seat through the connecting block promptly, and the rethread connecting piece correspondence passes bar hole and locking hole in order to fix the connecting block on the base, so adjust the sliding seat fixed to relative fixing base within range suitable with the clamping work piece, and this structural design is simple, need not to dispose extra actuating mechanism, and can effectively guarantee its clamping stability after adjusting the completion.

Above-mentioned technical scheme is preferred, the connecting piece is the bolt to make connecting block and base assembly stable, and convenient to detach readjust the position.

Preferably, in the above technical scheme, the tightening mechanism is a pneumatic tightening mechanism or a hydraulic tightening mechanism.

Preferably, in the above technical solution, the locking mechanism includes a fixed positioning block fixed at an end of the rotary column and a movable positioning block detachably connected to the fixed positioning block, the movable positioning block is provided with a connecting end at a side facing the tightening end, and the connecting end is used for fixing a workpiece; according to the technical scheme, the workpiece can be fixed on the movable positioning block simultaneously in the process of adjusting the clamping precision, the workpiece and the movable positioning block are integrally fixed on the fixed positioning block after the clamping precision of the device is adjusted, repeated meter calibration and alignment in the process of clamping the workpiece are not needed, and the labor intensity is reduced.

Above-mentioned technical scheme is preferred, fixed locating piece with the activity locating piece is the rectangular block and fixed through arranging in screw and pin all around, utilizes screw locking pin location to be convenient for install and assemble stably.

Above-mentioned technical scheme is preferred, the retaining member is fixing nut, be provided with on the column spinner with fixing nut internal thread matched with external screw thread, just the tip of column spinner is provided with the outer hexagonal of being convenient for to rotate, and the column spinner tip is screwed up to outside work piece of so accessible, and rethread fixing nut screws up the column spinner after the adjustment column spinner angle and fixes on the fixing base.

The utility model has at least the following beneficial effects:

1. aiming at the processing characteristics of a large-size complex inclined ejection structure, the clamping device can effectively utilize the locking mechanism on the fixed seat and the jacking mechanism on the movable seat to ensure the clamping stability of the clamping device, and utilize the rotating column to adjust the clamping precision of the workpiece, firstly utilize the rotating column to adjust the device precision and then clamp and fix the workpiece, the clamping precision is ensured by using a clamp, repeated meter correction and alignment in the clamping process are not needed, the clamping precision of the workpiece is controlled by the clamping device structure, and the precision can be effectively ensured.

2. The rotating column of the clamping device is fixed in the positioning hole of the fixing seat, and can be engaged with the positioning protrusion on the positioning surface of the rotating column through the positioning groove in the positioning hole to realize radial positioning between the rotating column and the positioning hole, so that after the angle of the rotating column is adjusted, the positioning stability of the rotating column can be ensured through the engagement structure and the locking part, the mounting precision can be ensured through the engagement angle between the positioning protrusion and the positioning groove and the scale on the side surface of the fixing seat, the clamping stability and precision of a workpiece can be further ensured, no additional driving mechanism is needed, the structure is simple, and the design is ingenious and reasonable.

3. The clamping device is suitable for quick clamping of medium and large complex pitched roofs/inserts, the actual utilization rate of a machine tool can be greatly improved by using the clamping device, the machining efficiency is improved, the labor intensity of operators is greatly reduced, the alignment precision is not controlled by the skill level of operators any more, the workpiece clamping time is greatly shortened, the comprehensive use precision of the clamping device can be controlled within 0.02mm, the workpiece machining quality is controlled, the part manufacturing period is shortened, and the clamping device has good popularization and practical values.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention, and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.

FIG. 1 is a schematic structural diagram of a clamping device according to an embodiment of the utility model;

FIG. 2 shows a schematic structural view of a spin column in an embodiment of the present invention;

FIG. 3 is a schematic cross-sectional view of a mounting bracket according to an embodiment of the utility model;

FIG. 4 is a schematic view illustrating the assembly of the spin column and the fixing base according to the embodiment of the present invention;

fig. 5 shows a schematic view of a pitched roof in the background of the utility model.

In the figure: 1-a base; 11-a locking hole; 12-a connector; 2-a fixed seat; 21-positioning holes; 211-positioning step; 212-a positioning groove; 22-rotation scale line; 3-a movable seat; 4-spin columns; 41-outer hexagon; 42-a positioning surface; 43-positioning protrusions; 5-a locking member; 6-adjusting the guide rail; 61-wear resistant block; 7-a jacking mechanism; 71-tightening the end; 8-a locking mechanism; 81-fixing a positioning block; 82-a movable positioning block; 821-a connecting end; 9-connecting blocks; 91-strip shaped holes; 10-inclined top.

Detailed Description

The utility model is further described with reference to the following figures and specific embodiments.

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. The components of embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.

Referring to fig. 1 to 4, the present embodiment provides a clamping device for a middle-large complex lifter, for clamping a lifter 10 in the background art, the clamping device includes a base 1, a fixed seat 2 disposed at a right end of the base 1, and a movable seat 3 disposed at a left end of the base 1, the fixed seat 2 and the movable seat 3 are disposed opposite to each other, wherein the fixed seat 2 is fixed on the base 1, and the fixed mode may be welding or integral molding; the fixed seat 2 is provided with a rotary column 4 and a positioning hole 21 for the rotary column 4 to pass through, the rotary column 4 transversely passes through the positioning hole 21 and is matched with the positioning hole 21 in a clinging manner to support stress, the positioning hole 21 has a guiding effect on the rotary column 4, so that the rotary column 4 can rotate more easily, the left end of the rotary column 4 facing the movable seat 3 is provided with a locking mechanism 8, the right end of the rotary column 4 is provided with a locking part 5 for fixing the rotary column 4 on the fixed seat 2, wherein the locking part 5 can be a fixed nut, the right end of the rotary column 4 is provided with an external thread matched with the internal thread of the fixed nut, and the right end of the rotary column 4 is provided with an external hexagonal socket cap 41 convenient to rotate, so that the end of the rotary column 4 can be screwed up through an external workpiece, the rotary column 4 is screwed up and fixed on the fixed seat 2 through the fixed nut after the angle of the rotary column 4 is adjusted, and the rotation angle of the rotary column 4 can be adjusted, the rotating column 4 can also be positioned and fixed in the positioning hole 21, so that the requirements of multi-surface processing, adjustment and clamping of the large and medium complex pitched roof 10 are met.

Critically, as shown in fig. 2 to 4, in this embodiment, a radially protruding positioning step 211 is disposed in the positioning hole 21 of the fixing base 2, a plurality of axially extending positioning grooves 212 are disposed on the positioning step 211 at intervals, a radially recessed positioning surface 42 is disposed at a position where the rotary column 4 extends into the positioning hole 21, a plurality of axially extending positioning protrusions 43 are uniformly disposed on the positioning surface 42, and the positioning protrusions 43 can be engaged with the positioning grooves 212, so that the rotary column 4 can pass through the positioning hole 21 to achieve radial positioning; so this embodiment can pass through the column spinner 4 rotation in the locating hole 21 in order to adjust 8 angles of locking mechanism, and then guarantee work piece clamping precision, and the location recess 212 that sets up on the location step 211 in the locating hole 21 meshes with the location boss on the column spinner 4 mutually, can avoid it to produce radial rotation after retaining member 5 fixes column spinner 4 to further guarantee work piece clamping and machining precision.

It is worth explaining that, when adjusting the angle of the rotating column 4, the embodiment needs to withdraw the positioning surface 42 of the rotating column 4 from the positioning step 211, and after the angle of the rotating column 4 is adjusted, the rotating column 4 is pushed towards one side of the positioning step 211, so that the positioning protrusion 43 of the rotating column 4 is embedded into the positioning groove 212 to realize the radial positioning of the rotating column 4, and then the rotating column 4 is fixed on the right side of the fixing seat 2 through the fixing nut, so as to ensure the radial and axial fixing of the rotating column 4.

Correspondingly, this embodiment is equipped with rotatory scale mark 22 in the left side of fixing base 2, rotatory scale mark 22 uses the axle center of column spinner 4 to evenly arrange in the outside of column spinner 4 as the center, set up on column spinner 4 with rotatory scale mark 22 matched with index (not shown), so can effectively guarantee the positioning accuracy of column spinner 4, this embodiment clamping device can directly fix a position the work piece through locking mechanism 8 after adjusting 4 location angle of column spinner, avoid proofreading and alignment repeatedly and have the big technical problem of the alignment degree of difficulty, work piece clamping accuracy receives device control, the precision can effectively be ensured.

In order to adjust the proper position of the movable seat 3 on the base 1, the base 1 is provided with an adjusting guide rail 6 in the embodiment, the adjusting guide rail 6 extends from the movable seat 3 to the fixed seat 2, and the movable seat 3 is connected to the adjusting guide rail 6 in a sliding manner; in order to facilitate the adjustment and fixation of the movable seat 3, the adjusting guide rail 6 is arranged below the top plane of the base 1 in the embodiment, the bottom of the movable seat 3 is provided with a connecting block 9, the movable seat 3 can be welded, screwed or integrally formed with the connecting block 9, the connecting block 9 is arranged on the base 1, the lower end of the connecting block 9 can be embedded into the adjusting guide rail 6 and can slide along the adjusting guide rail 6, and the adjusting guide rail 6 is provided with a wear-resistant block 61; so can effectively guarantee the smooth stability of connecting block 9 slip on adjusting guide rail 6, and the movable block constitutes its bearing capacity with connecting block 9 and can effectively guarantee with connecting block 9T type structure for tight mechanism 7 in top is fixed stable to the work piece.

Further, in this embodiment, strip-shaped holes 91 are formed in two sides of the connecting block 9 along the sliding direction of the movable seat 3, a plurality of locking holes 11 are arranged in the base 1 along the sliding direction of the movable seat 3, connecting pieces 12 are arranged in the strip-shaped holes 91, the connecting pieces 12 may be bolts, and the connecting pieces 12 can penetrate through the strip-shaped holes 91 and the locking holes 11 and are connected with the locking holes 11 through threads to fix the connecting block 9; this embodiment is adjusted earlier the fixed position of sliding seat 3 before the clamping work piece, removes sliding seat 3 through connecting block 9 promptly, and rethread connecting piece 12 corresponds and passes bar hole 91 and locking hole 11 in order to fix connecting block 9 on base 1, so adjust sliding seat 3 fixed to relative fixing base 2 suitable within ranges with the centre gripping work piece, and this structural design is simple, need not to dispose extra actuating mechanism, and can effectively guarantee its clamping stability after adjusting the completion.

In the illustrated embodiment, the movable seat 3 is provided with a tightening mechanism 7, one end of the tightening mechanism 7 facing the locking mechanism 8 is provided with a tightening end 71 so as to enable the locking mechanism 8 and the tightening end 71 to tighten and fix the workpiece, the tightening mechanism 7 provided in this embodiment is a pneumatic tightening mechanism, and the side wall of the movable seat 3 is further provided with an air inlet hole communicated with the pneumatic tightening mechanism; of course, the present invention is not limited to this, and in some embodiments, the tightening mechanism 7 may also be a hydraulic tightening device or other mechanical tightening devices, and is within the scope of the present invention.

The locking mechanism 8 of the embodiment includes a fixed positioning block 81 fixed at the end of the rotary column 4 and a movable positioning block 82 detachably connected with the fixed positioning block 81, the fixed positioning block 81 may be in threaded connection with the end of the rotary column 4 or welded or integrally formed, the movable positioning block 82 is provided with a connecting end 821 at one side facing the tightening end 71, and the connecting end 821 corresponds to the side mounting hole of the lifter 10 and can be used for fixing a workpiece; in the process of adjusting the clamping precision, the workpiece can be fixed on the movable positioning block 82 at the same time, and after the clamping precision of the device is adjusted, the workpiece and the movable positioning block 82 are integrally fixed on the fixed positioning block 81, so that repeated meter calibration and alignment in the process of clamping the workpiece are not needed, and the labor intensity is reduced; preferably, the fixed positioning block 81 and the movable positioning block 82 are rectangular blocks and fixed by screws and pins arranged on the periphery, and the pins are locked by screws to be positioned so as to facilitate installation and stable assembly.

With reference to fig. 1 to 5, the clamping device of the present embodiment is specifically implemented as follows:

the movable seat 3 on the adjusting guide rail 6 is moved according to the size of a workpiece of the inclined top 10, the movable seat 3 is adjusted to a proper range and is fixed by the connecting piece 12, the rotating column 4 is driven to rotate according to the requirement of a processing surface of the inclined top 10, specifically, the positioning surface 42 of the rotating column 4 is required to be withdrawn from the positioning step 211, after the angle of the rotating shaft is adjusted by combining the rotating scale mark 22 on the side surface of the fixed seat 2, the rotating column 4 is pushed axially, so that the positioning protrusion 43 is embedded into the positioning groove 212 to realize meshing, and then the rotating column 4 is fixed on the fixed seat 2 by using a fixing nut to realize the accurate positioning of the rotating column 4 in the radial direction and the axial direction; the installation angle of the fixed positioning block 81 positioned at the end part of the rotating column 4 is determined; fixing the connecting end 821 of the workpiece and the movable positioning block 82, fixing the movable positioning block 82 on the fixed positioning block 81, and locking the movable positioning block 82 and the fixed positioning block 81 by using screws and pins; finally, the pneumatic jacking mechanism 7 is started, the jacking end 71 of the pneumatic jacking mechanism is utilized to jack the workpiece, the workpiece is jacked obliquely 10, the angle of the device is adjusted before the workpiece is clamped, and the program machining can be started directly without aligning and calibrating the meter after the clamping is finished;

after the machining is finished, the pneumatic jacking mechanism 7 can be loosened, the screw between the movable positioning block 82 and the fixed positioning block 81 is loosened, the workpiece is taken down, if the workpiece needs to be machined in multiple angles, the rotating column 4 is adjusted to rotate and position, and then the process is repeated.

From above, this embodiment clamping device is to the complicated oblique top 10 structure processing characteristics of big shape, can effectively utilize on fixing base 2 locking mechanical system 8 and the sliding seat 3 to push up locking mechanical system 7 and guarantee its clamping stability, and utilize the column spinner 4 to adjust work piece clamping precision, utilize the column spinner 4 to fix the work piece with the device precision adjustment back reloading clamp earlier, the clamping precision uses anchor clamps to guarantee, need not again the clamping in-process to proofread and correct repeatedly, the work piece clamping precision receives clamping device structural control, and the precision can effectively be ensured.

It should be noted that, in the above embodiment, the clamping device is used for clamping the large complex lifter 10, but the clamping device is not limited to this, and may also be applied to other inserts requiring multi-surface machining, and all are within the protection scope of the present invention; the clamping device can greatly improve the actual utilization rate of the machine tool, improve the processing efficiency, greatly reduce the labor intensity of operators, ensure that the alignment precision does not depend on the control of the skill level of operators, is simple and convenient to use, stably control the single-side clamping time within 2 minutes, greatly shorten the workpiece clamping time, control the comprehensive use precision of the clamping device within 0.02mm, and has high clamping precision, so that the processing quality of workpieces is controlled, the part manufacturing period is shortened, and the clamping device has better popularization and application values and is suitable for popularization and application.

The present specification and figures are to be regarded as illustrative rather than restrictive, and it is intended that all such alterations and modifications that fall within the true spirit and scope of the utility model, and that all such modifications and variations are included within the scope of the utility model as determined by the appended claims without the use of inventive faculty.

Claims

1. The utility model provides a clamping device that is used for complicated oblique top of well big shape which characterized in that: comprises a base, a fixed seat and a movable seat which are oppositely arranged at two ends of the base, wherein

2. The clamping device for the medium and large complex pitched roof according to claim 1, characterized in that: the positioning hole is internally provided with a positioning step which protrudes along the radial direction, the positioning step is provided with a plurality of positioning grooves which extend axially at intervals, the part of the rotating column which extends into the positioning hole is provided with a positioning surface which is recessed along the radial direction, the positioning surface is evenly provided with a plurality of positioning protrusions which extend axially, and the positioning protrusions can be meshed with the positioning grooves, so that the rotating column can realize radial positioning after penetrating through the positioning hole.

3. The clamping device for the medium and large complex pitched roof according to claim 2, characterized in that: the side of fixing base is equipped with rotatory scale mark, rotatory scale mark with the axle center of column spinner is the even arrangement in the outside of column spinner the last index that sets up and rotatory scale mark matched with of column spinner.

4. The clamping device for the medium and large complex pitched roof according to claim 1, characterized in that: the adjusting guide rail is arranged below the plane of the top of the base, the bottom of the movable seat is provided with a connecting block, and the lower end of the connecting block can be embedded into the adjusting guide rail and slides along the adjusting guide rail.

5. The clamping device for the medium and large complex pitched roof according to claim 4, wherein: the connecting block is followed the both sides of sliding direction of sliding seat are provided with the bar hole, the base is followed sliding direction of sliding seat arranges and is provided with a plurality of locking hole, the downthehole connecting piece that has arranged of bar, the connecting piece can pass the bar hole and lock the hole with fixed the connecting block.

6. The clamping device for the medium and large complex pitched roof according to claim 5, wherein: the connecting piece is a bolt.

7. The clamping device for the medium and large complex pitched roof according to claim 1, characterized in that: the jacking mechanism is a pneumatic jacking mechanism or a hydraulic jacking mechanism.

8. The clamping device for the medium and large complex pitched roof according to claim 1, characterized in that: the locking mechanism comprises a fixed positioning block fixed at the end part of the rotary column and a movable positioning block detachably connected with the fixed positioning block, a connecting end is arranged on one side of the movable positioning block facing the tightening end, and the connecting end is used for fixing a workpiece.

9. The clamping device for the medium and large complex pitched roof according to claim 8, wherein: the fixed locating piece with the activity locating piece is the rectangular block and fixed through arranging screw and pin all around.

10. The clamping device for the medium and large complex pitched roof according to claim 1, characterized in that: the retaining member is fixing nut, be provided with on the column spinner with fixing nut internal thread matched with external screw thread, just the tip of column spinner is provided with the outer hexagonal of being convenient for it is rotatory.