CN216002011U

CN216002011U - Drawing compasses that chalk is difficult for fracture for junior high school mathematics

Info

Publication number: CN216002011U
Application number: CN202023263139.5U
Authority: CN
Inventors: 郭修臣; 陈秀丽; 梁光荣; 范志敏
Original assignee: Individual
Current assignee: Individual
Priority date: 2020-12-31
Filing date: 2020-12-31
Publication date: 2022-03-11
Anticipated expiration: 2030-12-31

Abstract

The application discloses compasses of drawing of chalk difficult fracture for junior high school mathematics, including center post, fixed knot structure, drawing structure and regulation structure, the first fixed column of center post top rigid coupling, fixed knot structure includes the second fixed column, second fixed column rigid coupling in center bottom of the column portion, second fixed column surface sliding connection sliding sleeve, sliding sleeve bottom rigid coupling slipmat, second fixed column side rigid coupling sliding plate. This application is rational in infrastructure, be convenient for the injecing of drawing compasses position through first spring and second spring isotructure, prevent that the drawing compasses from taking place to remove when using, can remove and injecing the position of chalk cover through removing lagging and first screw post isotructure, thereby be convenient for adjust the circular shape radius of drawing, can adjust the position of extension plate through third screw post and reference column isotructure, be convenient for draw the longer circular of diameter, improve the application scope of drawing compasses, the teaching of the mathematics of being convenient for.

Description

Drawing compasses that chalk is difficult for fracture for junior high school mathematics

Technical Field

The application relates to a drawing compass, in particular to a drawing compass with a chalk not prone to fracture for junior high school mathematics.

Background

In mathematics and drawing, compasses are used for drawing circles or strings, are usually used for drawing by ruler compasses, and are used for drawing.

At present need draw the compasses and carry out circular drawing in junior middle school mathematics teaching process often, but current compasses need draw the radius of regulation length with the ruler in advance, utilize the radius to carry out the drawing of circle, and operating procedure is loaded down with trivial details, extravagant teaching time, and at the in-process of drawing, two feet of compasses take place to remove easily, the going on of drawing the circle of not being convenient for. Therefore, the drawing compasses are provided for solving the problems that chalks for junior high school mathematics are not easy to break.

Disclosure of Invention

A drawing compass with a chalk not prone to fracture for junior middle school mathematics comprises a central column, a fixing structure, a drawing structure and an adjusting structure, wherein the top of the central column is fixedly connected with a first fixing column;

the fixed structure comprises a second fixed column, the second fixed column is fixedly connected to the bottom of the central column, the surface of the second fixed column is connected with a sliding sleeve in a sliding mode, the bottom of the sliding sleeve is fixedly connected with an anti-skid pad, the side face of the second fixed column is fixedly connected with a sliding plate, the sliding plate is connected to the surface of a limiting column in a sliding mode, the limiting column is fixedly connected to the bottom of an inner cavity of the sliding sleeve, the bottom of the inner cavity of the sliding sleeve is fixedly connected with a first spring, the side face of the first spring is provided with a second spring, and the second spring is fixedly connected to the bottom end of the second fixed column;

the drawing structure comprises a rotating sleeve, the rotating sleeve is rotatably connected to the surface of a central column, one side of the rotating sleeve is fixedly connected with a fixed sleeve, the surface of the fixed sleeve is slidably connected with a movable sleeve plate, the top of the movable sleeve plate is in threaded connection with a first threaded column, the bottom of the movable sleeve plate is fixedly connected with a second threaded column, the surface of the second threaded column is in threaded connection with a first threaded sleeve, the bottom of the first threaded sleeve is fixedly connected with a chalk sleeve, and the surface of the chalk sleeve is in threaded connection with a fixed nut;

the adjusting structure comprises a third threaded column, the third threaded column is in threaded connection with the inner wall of the fixed sleeve, one end of the third threaded column is fixedly connected with an extension plate, one side of the extension plate is rotated to be connected with a rotating plate, one side of the rotating plate is fixedly connected with a reference column, the reference column is in sliding connection with the inner wall of the fixed sleeve, the other side of the rotating plate is fixedly connected with a fourth threaded column, the surface of the fourth threaded column is in threaded connection with a second threaded sleeve, and one side of the second threaded sleeve is fixedly connected with a mounting plate.

Furthermore, the sliding plate is provided with four limiting ports distributed in a rectangular structure, four limiting columns distributed in a rectangular structure are fixedly connected to the bottom of the inner cavity of the sliding sleeve, and the top ends of the limiting columns penetrate through the limiting ports and are fixedly connected to the top of the inner cavity of the sliding sleeve.

Furthermore, the top end of the first spring is fixedly connected with the bottom of the limiting column, the bottom end of the first spring is fixedly connected with the bottom of the inner cavity of the sliding sleeve, and the first spring is sleeved on the surface of the limiting column.

Furthermore, the top end of the second spring is fixedly connected to the bottom of the second fixed column, and the bottom end of the second spring is fixedly connected to the bottom of the inner cavity of the sliding sleeve.

Furthermore, the outer surface of the central column is fixedly connected with two symmetrically distributed fixing sleeves, and the fixing sleeves are provided with thread grooves and four sliding grooves distributed in a rectangular structure.

Furthermore, the third threaded column is in threaded connection with the fixed sleeve through a threaded groove, four positioning columns distributed in a rectangular structure are fixedly connected to one side of the rotating plate, and the positioning columns are connected to the side wall of the sliding groove in a sliding mode.

Furthermore, the top of the movable sleeve plate is provided with a threaded opening, the top end of the movable sleeve plate penetrates through the threaded opening and extends to the upper part of the movable sleeve plate, and the top end of the movable sleeve plate is fixedly connected with a rotating handle.

Furthermore, the surface of the chalk sleeve is provided with two symmetrically distributed clamping seams, and the surface of the chalk sleeve is provided with an external thread.

Further, the extension plate is provided with a rotating cavity and four communicating ports distributed in a rectangular structure, the rotating cavity is communicated with the communicating ports, and one end of the positioning column penetrates through the communicating ports and extends to one side of the extension plate.

Further, the mounting panel has second screw thread post with the equal rigid coupling in removal lagging bottom, just the equal threaded connection in second screw thread post surface has first screw sleeve, scale mark has all been carved with on fixed sleeve and reference column surface.

The beneficial effect of this application is: the application provides a drawing compass with a chalk not prone to fracture for junior middle school mathematics.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without inventive exercise.

FIG. 1 is a schematic overall perspective view of an embodiment of the present application;

FIG. 2 is a schematic diagram of the overall internal structure of an embodiment of the present application;

FIG. 3 is a schematic overall side view of an embodiment of the present application;

FIG. 4 is a schematic illustration of a side view of an extension plate according to an embodiment of the present disclosure;

FIG. 5 is a schematic top view of a sliding sleeve according to an embodiment of the present application;

FIG. 6 is an enlarged view of a portion of the structure of FIG. 2 according to an embodiment of the present disclosure;

fig. 7 is a schematic view of a portion of the enlarged structure at B in fig. 2 according to an embodiment of the present application.

In the figure: 1. center post, 2, first fixed column, 3, second fixed column, 4, sliding sleeve, 5, slipmat, 6, sliding plate, 7, spacing post, 8, first spring, 9, second spring, 10, rotating sleeve, 11, fixed sleeve, 12, removal lagging, 13, first screw post, 14, second screw post, 15, first screw sleeve, 16, chalk cover, 17, fixation nut, 18, third screw post, 19, extension plate, 20, rotor plate, 21, reference column, 22, fourth screw post, 23, second screw sleeve, 24, mounting panel.

Detailed Description

In order to make the technical solutions better understood by those skilled in the art, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only partial embodiments of the present application, but not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

It should be noted that the terms "first," "second," and the like in the description and claims of this application and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It should be understood that the data so used may be interchanged under appropriate circumstances such that embodiments of the application described herein may be used. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.

In this application, the terms "upper", "lower", "left", "right", "front", "rear", "top", "bottom", "inner", "outer", "middle", "vertical", "horizontal", "lateral", "longitudinal", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings. These terms are used primarily to better describe the present application and its embodiments, and are not used to limit the indicated devices, elements or components to a particular orientation or to be constructed and operated in a particular orientation.

Moreover, some of the above terms may be used to indicate other meanings besides the orientation or positional relationship, for example, the term "on" may also be used to indicate some kind of attachment or connection relationship in some cases. The specific meaning of these terms in this application will be understood by those of ordinary skill in the art as appropriate.

Furthermore, the terms "mounted," "disposed," "provided," "connected," and "sleeved" are to be construed broadly. For example, it may be a fixed connection, a removable connection, or a unitary construction; can be a mechanical connection, or an electrical connection; may be directly connected, or indirectly connected through intervening media, or may be in internal communication between two devices, elements or components. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art as appropriate.

It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present application will be described in detail below with reference to the embodiments with reference to the attached drawings.

Referring to fig. 1-7, a drawing compass with a hardly breakable chalk for mathematics in junior middle schools comprises a central column 1, a fixing structure, a drawing structure and an adjusting structure, wherein a first fixing column 2 is fixedly connected to the top of the central column 1;

the fixing structure comprises a second fixing column 3, the second fixing column 3 is fixedly connected to the bottom of the central column 1, the surface of the second fixing column 3 is connected with a sliding sleeve 4 in a sliding mode, the bottom of the sliding sleeve 4 is fixedly connected with an anti-skid pad 5, the side face of the second fixing column 3 is fixedly connected with a sliding plate 6, the sliding plate 6 is connected to the surface of a limiting column 7 in a sliding mode, the limiting column 7 is fixedly connected to the bottom of an inner cavity of the sliding sleeve 4, the bottom of the inner cavity of the sliding sleeve 4 is fixedly connected with a first spring 8, a second spring 9 is arranged on the side face of the first spring 8, and the second spring 9 is fixedly connected to the bottom end of the second fixing column 3;

the drawing structure comprises a rotating sleeve 10, wherein the rotating sleeve 10 is rotatably connected to the surface of a central column 1, one side of the rotating sleeve 10 is fixedly connected with a fixed sleeve 11, the surface of the fixed sleeve 11 is slidably connected with a movable sleeve plate 12, the top of the movable sleeve plate 12 is in threaded connection with a first threaded column 13, the bottom of the movable sleeve plate 12 is fixedly connected with a second threaded column 14, the surface of the second threaded column 14 is in threaded connection with a first threaded sleeve 15, the bottom of the first threaded sleeve 15 is fixedly connected with a chalk sleeve 16, and the surface of the chalk sleeve 16 is in threaded connection with a fixed nut 17;

the adjusting structure includes third

screw thread post

18, 18 threaded connection of third screw thread post is in 11 inner walls of fixed sleeve, 18 one end rigid coupling extension plates 19 of third screw thread post, 19 one sides of extension plates are rotated and are connected

rotor plate

20, 20 one side rigid coupling reference columns 21 of rotor plate, 21 sliding connection of reference columns in 11 inner walls of fixed sleeve, 20 opposite side rigid coupling fourth screw thread posts 22 of rotor plate, 22 surperficial threaded connection second screw thread sleeves 23 of fourth screw thread post, 23 one side rigid coupling mounting panels 24 of second screw thread sleeves.

The sliding plate 6 is provided with four limiting ports distributed in a rectangular structure, four limiting columns 7 distributed in a rectangular structure are fixedly connected to the bottom of the inner cavity of the sliding sleeve 4, and the top ends of the limiting columns 7 penetrate through the limiting ports and are fixedly connected to the top of the inner cavity of the sliding sleeve 4; the top end of the first spring 8 is fixedly connected with the bottom of the limiting post 7, the bottom end of the first spring 8 is fixedly connected with the bottom of the inner cavity of the sliding sleeve 4, and the first spring 8 is sleeved on the surface of the limiting post 7; the top end of the second spring 9 is fixedly connected to the bottom of the second fixed column 3, and the bottom end of the second spring 9 is fixedly connected to the bottom of the inner cavity of the sliding sleeve 4; two symmetrically distributed fixing sleeves 11 are fixedly connected to the outer surface of the central column 1, and the fixing sleeves 11 are provided with thread grooves and four sliding grooves distributed in a rectangular structure; the third threaded column 18 is in threaded connection with the fixed sleeve 11 through a threaded groove, one side of the rotating plate 20 is fixedly connected with four positioning columns 21 distributed in a rectangular structure, and the positioning columns 21 are connected to the side wall of the sliding groove in a sliding manner; the top of the movable sleeve plate 12 is provided with a threaded hole, the top end of the movable sleeve plate 12 penetrates through the threaded hole and extends to the upper part of the movable sleeve plate 12, and the top end of the movable sleeve plate 12 is fixedly connected with a rotating handle; the surface of the chalk sleeve 16 is provided with two symmetrically distributed clamping seams, and the surface of the chalk sleeve 16 is provided with an external thread; the extension plate 19 is provided with a rotating cavity and four communicating ports distributed in a rectangular structure, the rotating cavity is communicated with the communicating ports, and one end of the positioning column 21 penetrates through the communicating ports and extends to one side of the extension plate 19; mounting panel 24 and the equal rigid coupling in removal lagging 12 bottom have second screw thread post 14, just the equal threaded connection in second screw thread post 14 surface has first threaded sleeve 15, scale mark has all been carved with on fixed sleeve 11 and the reference column 21 surface.

When the chalk box is used, electrical elements appearing in the chalk box are externally connected with a power supply and a control switch when the chalk box is used, firstly, chalk is put into the chalk sleeve 16 to enable the chalk to expose a short section, then the fixing screw cap 17 is rotated to enable the fixing screw cap 17 to slide downwards along the chalk sleeve 16 so as to limit the position of the chalk, prevent the chalk from falling or breaking, facilitate the round drawing on a blackboard by using the chalk, then, a movable sleeve plate 12 is slid according to the radius of the round to be drawn so as to drive the second threaded columns 14 to move in the same direction, so as to drive the first threaded sleeves 15 to move in the same direction, so as to drive the chalk sleeve 16 to move in the same direction, so as to adjust the structures of the movable sleeve plate 12 to the radius of the circle to be drawn according to the scale marks on the fixed sleeve 11, then, the first threaded columns 13 are rotated by using the rotating handle, so as to enable the bottoms of the first threaded columns 13 to be tightly attached to the surface of the fixed sleeve 11, thereby limiting the position of the moving sleeve plate 12 and the like, thereby limiting the position of the chalk sleeve 16 and the like, then adjusting and limiting the position of the moving sleeve plate 12 on the other side in the same way, thereby enabling the distance between the two chalk sleeves 16 to be the same as the diameter of a circle, then rotating the first threaded sleeve 15 below the moving sleeve plate 12, thereby enabling the first threaded sleeve 15 to move along the second threaded column 14, enabling the bottom end of the chalk sleeve 16 below the moving sleeve plate 12 to be higher than the chalk sleeve 16 below the mounting plate 24, then placing the sliding sleeve 4 and the anti-slip mat 5 at the blackboard, then pressing the first fixed column 2, thereby enabling the central column 1 to move towards the blackboard, thereby driving the second fixed column 3 to move in the same direction, thereby driving the sliding plate 6 to move in the same direction along the limiting column 7, thereby compressing the first spring 8 and the second spring 9, thereby enabling the sliding sleeve 4 and the anti-slip mat 5 to be tightly attached, thereby limiting the position of the central column 1 and other structures, preventing the central column 1 from moving in the process of drawing a circle, facilitating the process of drawing a circle, then rotating the fixed sleeve 11, thereby driving the rotating sleeve 10 to rotate around the central column 1, thereby driving the movable sleeve plate 12 to rotate, thereby driving the chalk sleeve 16 to rotate, thereby driving the chalk to rotate, thereby drawing a circle on the blackboard, avoiding the need of drawing straight lines with different lengths by using a ruler in advance when drawing different diameters, reducing the time for drawing a circle, when drawing a circle with a larger radius, firstly rotating the first threaded sleeve 15 below the movable sleeve plate 12, thereby enabling the first threaded sleeve 15 to move upwards along the second threaded column 14, thereby driving the chalk sleeve 16 to move upwards, then rotating the extension plate 19, thereby driving the third threaded column 18 to rotate, thereby enabling the third threaded column 18 to move along the fixed sleeve 11, thereby adjusting the position of the mounting plate 24, then the second screw sleeve 23 is rotated to adjust the angle of the chalk sleeve 16 under the mounting plate 24, so that the chalk sleeve 16 is parallel to the sliding sleeve 4, then the first screw sleeve 15 under the mounting plate 24 is rotated to move the first screw sleeve 15 along the second screw post 14, so that the chalk sleeve 16 moves in the same direction, so that the bottom end of the chalk sleeve 16 under the mounting plate 24 is higher than the bottom end of the chalk sleeve 16 under the movable sleeve plate 12, then the chalk sleeve 16 and the chalk under the mounting plate 24 are used for drawing a circle with a larger radius, and when the chalk sleeve 16 under the mounting plate 24 is used for drawing, the connecting structure between the extension plate 19 and the rotating sleeve 10 can be stronger through the positioning post 21 and the like, so that the painting is more stable, the circle drawing is facilitated, the circle drawing time is reduced, and the teaching of mathematics in the beginning is facilitated.

The application has the advantages that:

1. the structure is simple, the drawing compasses can be pressed on the blackboard through the structures such as the sliding sleeve, the non-slip mat and the like, the limiting of the positions of the drawing compasses is facilitated through the structures such as the first spring, the second spring and the like, the drawing compasses are prevented from moving when being used, and the circular drawing is prevented from being influenced;

2. the chalk sleeve is reasonable in structure, the chalk sleeve can be conveniently rotated through the rotating sleeve, the fixing sleeve and the like, so that circular drawing can be conveniently performed on the drawing board, the position of the chalk sleeve can be moved and limited through the movable sleeve plate, the first threaded column and the like, so that the radius of the drawn circle can be conveniently adjusted, chalk can be conveniently fixed through the chalk sleeve and the fixing nut, the chalk is prevented from being easily broken due to the fact that the exposed length of the chalk is too long, and circular drawing is convenient;

3. this application easy operation can adjust the position of extension plate through third screw thread post and reference column isotructure, is convenient for draw the longer circular of diameter, improves the application scope of drawing compasses for draw the circular shape time, prevent extravagant mathematics teaching classroom's time, the teaching of the mathematics of being convenient for.

The above description is only a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. The utility model provides a drawing compasses that junior middle school mathematics is difficult for fracture with chalk which characterized in that: the device comprises a central column (1), a fixing structure, a drawing structure and an adjusting structure, wherein the top of the central column (1) is fixedly connected with a first fixing column (2);

the fixing structure comprises a second fixing column (3), the second fixing column (3) is fixedly connected to the bottom of the central column (1), the surface of the second fixing column (3) is connected with a sliding sleeve (4) in a sliding mode, the bottom of the sliding sleeve (4) is fixedly connected with an anti-slip pad (5), the side face of the second fixing column (3) is fixedly connected with a sliding plate (6), the sliding plate (6) is connected to the surface of a limiting column (7) in a sliding mode, the limiting column (7) is fixedly connected to the bottom of an inner cavity of the sliding sleeve (4), the bottom of the inner cavity of the sliding sleeve (4) is fixedly connected with a first spring (8), a second spring (9) is arranged on the side face of the first spring (8), and the second spring (9) is fixedly connected to the bottom end of the second fixing column (3);

the drawing structure comprises a rotating sleeve (10), the rotating sleeve (10) is rotatably connected to the surface of a central column (1), one side of the rotating sleeve (10) is fixedly connected with a fixed sleeve (11), the surface of the fixed sleeve (11) is in sliding connection with a movable sleeve plate (12), the top of the movable sleeve plate (12) is in threaded connection with a first threaded column (13), the bottom of the movable sleeve plate (12) is fixedly connected with a second threaded column (14), the surface of the second threaded column (14) is in threaded connection with a first threaded sleeve (15), the bottom of the first threaded sleeve (15) is fixedly connected with a chalk sleeve (16), and the surface of the chalk sleeve (16) is in threaded connection with a fixed nut (17);

the adjusting structure comprises a third threaded column (18), the third threaded column (18) is in threaded connection with the inner wall of the fixed sleeve (11), one end of the third threaded column (18) is fixedly connected with an extension plate (19), one side of the extension plate (19) is rotated to be connected with a rotating plate (20), one side of the rotating plate (20) is fixedly connected with a positioning column (21), the positioning column (21) is in sliding connection with the inner wall of the fixed sleeve (11), the other side of the rotating plate (20) is fixedly connected with a fourth threaded column (22), the surface of the fourth threaded column (22) is in threaded connection with a second threaded sleeve (23), and one side of the second threaded sleeve (23) is fixedly connected with a mounting plate (24).

2. The drawing compass, which is not easy to break with chalk for junior middle school mathematics, according to claim 1, is characterized in that: four limiting ports distributed in a rectangular structure are formed in the sliding plate (6), four limiting columns (7) distributed in a rectangular structure are fixedly connected to the bottom of the inner cavity of the sliding sleeve (4), and the top ends of the limiting columns (7) penetrate through the limiting ports and are fixedly connected to the top of the inner cavity of the sliding sleeve (4).

3. The drawing compass, which is not easy to break with chalk for junior middle school mathematics, according to claim 1, is characterized in that: the top end of the first spring (8) is fixedly connected with the bottom of the limiting column (7), the bottom end of the first spring (8) is fixedly connected with the bottom of the inner cavity of the sliding sleeve (4), and the first spring (8) is sleeved on the surface of the limiting column (7).

4. The drawing compass, which is not easy to break with chalk for junior middle school mathematics, according to claim 1, is characterized in that: the top end of the second spring (9) is fixedly connected to the bottom of the second fixing column (3), and the bottom end of the second spring (9) is fixedly connected to the bottom of the inner cavity of the sliding sleeve (4).

5. The drawing compass, which is not easy to break with chalk for junior middle school mathematics, according to claim 1, is characterized in that: the outer surface of the central column (1) is fixedly connected with two symmetrically distributed fixing sleeves (11), and the fixing sleeves (11) are provided with thread grooves and four sliding grooves distributed in a rectangular structure.

6. The drawing compass, which is not easy to break with chalk for junior middle school mathematics, according to claim 5, is characterized in that: third screw thread post (18) are through thread groove and fixed sleeve (11) threaded connection, rotor plate (20) one side rigid coupling has four reference column (21) that are the distribution of rectangle structure, just reference column (21) sliding connection is in the sliding tray lateral wall.

7. The drawing compass, which is not easy to break with chalk for junior middle school mathematics, according to claim 1, is characterized in that: the top of the movable sleeve plate (12) is provided with a threaded opening, the top end of the movable sleeve plate (12) penetrates through the threaded opening and extends to the upper part of the movable sleeve plate (12), and the top end of the movable sleeve plate (12) is fixedly connected with a rotating handle.

8. The drawing compass, which is not easy to break with chalk for junior middle school mathematics, according to claim 1, is characterized in that: the chalk sleeve is characterized in that two symmetrically distributed clamping seams are formed in the surface of the chalk sleeve (16), and external threads are formed in the surface of the chalk sleeve (16).

9. The drawing compass, which is not easy to break with chalk for junior middle school mathematics, according to claim 1, is characterized in that: the extension plate (19) is provided with a rotating cavity and four communicating ports distributed in a rectangular structure, the rotating cavity is communicated with the communicating ports, and one end of the positioning column (21) penetrates through the communicating ports and extends to one side of the extension plate (19).

10. The drawing compass, which is not easy to break with chalk for junior middle school mathematics, according to claim 1, is characterized in that: mounting panel (24) and the equal rigid coupling in removal lagging (12) bottom have second screw thread post (14), just the equal threaded connection in second screw thread post (14) surface has first threaded sleeve (15), scale mark has all been carved with on fixed sleeve (11) and reference column (21) surface.