阅读说明：本技术 一种数学教学用自动画图装置 (Mathematics teaching is with automatic drawing device ) 是由 代美丽 安莉 庄波 于 2021-02-04 设计创作，主要内容包括：本发明公开了一种数学教学用自动画图装置,涉及教学用具技术领域,其包括环形外轨,环形外轨的内壁固定设置有环形齿条,环形外轨的前侧壁左右端均固定设置有L形支撑杆,两个L形支撑杆的相对侧固定设置有安装座。该数学教学用自动画图装置,通过在环形外轨内设置的旋转长条板,当伺服电机的输出轴带动旋转长条板在环形外轨内旋转时,进而可以实现带动两个滑筒做环形运动,此时两个滑筒内粉笔安装座上夹持的粉笔可以随着圆筒旋转一百八十度在黑板上画出两个半圆线,两个半圆线刚好可以形成一个圆形,进而可实现在黑板上画出标准的圆形,相对与老师手动画圆,能够避免画出的圆形存在偏差,导致学生理解出现偏差等,使学生更容易理解等。(The invention discloses an automatic drawing device for mathematical education, and relates to the technical field of teaching aids. This automatic drawing device is used in mathematical education, through the rotatory rectangular board that sets up in the annular outer rail, when servo motor's output shaft drives rotatory rectangular board when annular outer rail internal rotation, and then can realize driving two slide cartridges and be the annular motion, the chalk of centre gripping can be along with the rotatory one hundred eighty degrees of drum two semicircle lines of drawing on the chalk mount pad in two slide cartridges this moment, two semicircle lines just can form a circular, and then can realize drawing out standard circular on the blackboard, relative and the manual drawing circle of mr, the circular existence deviation that can avoid drawing, lead to the student to understand the deviation etc. that appears, make the student understand etc. more easily.)

1. The utility model provides a mathematics teaching is with automatic drawing device, includes annular outer rail (1), its characterized in that: the inner wall of the annular outer rail (1) is fixedly provided with an annular rack (2), the left end and the right end of the front side wall of the annular outer rail (1) are fixedly provided with L-shaped supporting rods (3), opposite sides of the two L-shaped supporting rods (3) are fixedly provided with mounting seats (4), the rear side of each mounting seat (4) is fixedly provided with a servo motor (6), an output shaft of each servo motor (6) is fixedly provided with a rotary strip plate (7), the upper side and the lower side of each rotary strip plate (7) are respectively provided with a strip-shaped sliding groove (10), the two strip-shaped sliding grooves (10) are internally provided with sliding barrels (11) in a sliding manner, the left side and the right side of the front side wall of each mounting seat (4) are respectively provided with a first switch (22) and a second switch (23), the upper side and the lower side of the front side wall of each mounting seat (4) are respectively provided with a display screen (24) and a digital button, and the left side of circle groove (26) and two rectangular spout (10) intercommunication, middle part fixed mounting has double-shaft motor (27) in circle groove (26), two output shafts of double-shaft motor (27) are all fixed and are provided with rotary rod (28), two spiral line (29), two have all been seted up with the part that two rectangular spout (10) correspond on rotary rod (28) the equal threaded connection of part of seting up spiral line (29) has a screw thread section of thick bamboo (30), two on rotary rod (28) the left side wall of screw thread section of thick bamboo (30) all is through connecting block and two slide cartridge (11) fixed connection.

2. The automatic drawing device for mathematical education as set forth in claim 1, wherein: the handle (5) is fixedly arranged at the bottom end of the front side of the mounting seat (4), and an arc-shaped groove is formed in the rear side wall of the handle (5).

3. The automatic drawing device for mathematical education as set forth in claim 1, wherein: gear grooves (8) are formed in the upper end and the lower end of the rotary strip plate (7), gears (9) are installed in the gear grooves (8), and the two gears (9) are meshed with the annular rack (2).

4. The automatic drawing device for mathematical education as set forth in claim 1, wherein: the chalk holder is characterized in that a threaded groove (12) formed in the front side wall of the sliding barrel (11) is connected with a screw rod (13) in an internal thread mode, a spring (14) is fixedly arranged at the rear end of the screw rod (13), the rear end of the spring (14) is fixedly connected with a T-shaped circular sliding block (15), the T-shaped circular sliding block (15) is arranged in a T-shaped circular sliding groove (16) in a sliding mode, and the T-shaped circular sliding block (16) is arranged on the front side wall of the chalk holder (17).

5. The automatic drawing device for mathematics teaching of claim 4, wherein: the chalk mounting structure is characterized in that a mounting groove (18) is formed in the rear side wall of the chalk mounting seat (17), an extrusion pad (19) is fixedly arranged on the side wall of the mounting groove (18), and chalk (20) is arranged in the mounting groove (18).

6. The automatic drawing device for mathematical education as set forth in claim 1, wherein: the first switch (22) and the second switch (23) are in a circle drawing mode and an ellipse drawing mode respectively, and the first switch (22) and the second switch (23) are both button switches.

7. The automatic drawing device for mathematical education as set forth in claim 1, wherein: the intelligent control device is characterized in that an intelligent control module (21) and a storage battery (31) are fixedly mounted in the mounting seat (4), a charging socket (32) is fixedly mounted on the top side wall of the mounting seat (4), and the type of the charging socket (32) is a USB-C port.

8. An automatic drawing device for mathematics teaching according to claim 1, 6 or 7, characterized in that: two the preceding lateral wall that the left side of rectangular spout (10) is located rotatory rectangular board (7) all is provided with centimetre scale mark (33), and the scale initial point of two centimetre scale marks (33) is the centre of a circle department of annular outer rail (1).

9. An automatic drawing device for mathematical education as claimed in claim 1 or 7, wherein: the output of charging socket (32) is connected with the input of battery (31) electricity, the output of battery (31) is connected with the input of intelligent control module (21) electricity, the output of intelligent control module (21) is connected with the input electricity of servo motor (6), double-shaft motor (27) and display screen (24), the output of switch (22), switch two (23) and digital button key (25) is connected with the input electricity of intelligent control module (21).

Technical Field

The invention relates to the technical field of teaching aids, in particular to an automatic drawing device for mathematical teaching.

Background

Mathematics is a subject of researching concepts such as quantity, structure, change, space, information and the like, is a universal means for strictly describing abstract structures and modes of things by human beings, can be applied to any problem in the real world, all mathematical objects are artificially defined essentially, and in this sense, the mathematics belongs to formal science, but not natural science, different mathematicians and philosophers have a series of opinions on the exact range and definition of the mathematics, and the mathematics plays an irreplaceable role in human historical development and social life and is also an essential basic tool for learning and researching modern scientific technology.

In the high school teaching process, the drawing is one of the necessary knowledge, general mr does not also can draw with the help of drawing utensil when drawing circle or ellipse, but because the circle or the ellipse that draw have certain deviation, can lead to the student to understand the deviation etc. and current drawing device still needs mr manual operation to go to draw when using, can reduce the availability factor, and traditional drawing device structure is too single, or can only draw circularly, or can only draw the ellipse, and circular or oval size also conveniently adjusts, not only extravagant mr's the time of going to school when the operation, can delay the course process simultaneously, bring inconvenience for mr and study in the study of studying.

Therefore, there is a need for an automatic drawing device for mathematical education to solve the above problems.

Disclosure of Invention

Technical problem to be solved

The invention provides an automatic drawing device for mathematical education, aiming at overcoming the defects of the prior art, and solving the problems that when a teacher draws a circle or an ellipse, the drawn circle or ellipse has certain deviation, so that the student understands the deviation, and the like.

(II) technical scheme

In order to achieve the above purposes, the technical scheme adopted by the invention is as follows: an automatic drawing device for mathematics teaching comprises an annular outer rail, wherein an annular rack is fixedly arranged on the inner wall of the annular outer rail, L-shaped supporting rods are fixedly arranged at the left end and the right end of the front side wall of the annular outer rail, mounting seats are fixedly arranged at the opposite sides of the two L-shaped supporting rods, a servo motor is fixedly arranged at the rear side of each mounting seat, a rotary strip plate is fixedly arranged on an output shaft of the servo motor, strip-shaped sliding grooves are respectively formed in the upper side and the lower side of the rotary strip plate, sliding cylinders are respectively arranged in the two strip-shaped sliding grooves in a sliding manner, a first switch and a second switch are respectively arranged at the left side and the right side of the front side wall of each mounting seat, a display screen and a digital button key are respectively arranged at the upper side and the lower side of the front side wall of each mounting seat, a circular groove is formed in one side of the rotary strip plate close to the right, two output shafts of biax motor are all fixed and are provided with the rotary rod, two the spiral line has all been seted up with the part that two rectangular spouts correspond on the rotary rod, two the equal threaded connection of part of seting up the spiral line on the rotary rod has a screw thread section of thick bamboo, two the left side wall of a screw thread section of thick bamboo all is through connecting block and two smooth section of thick bamboo fixed connection.

Preferably, a handle is fixedly arranged at the bottom end of the front side of the mounting seat, and an arc-shaped groove is formed in the rear side wall of the handle.

Preferably, gear grooves are formed in the upper end and the lower end of the rotary strip plate, gears are mounted in the gear grooves, and the two gears are meshed with the annular rack.

Preferably, a threaded groove formed in the front side wall of the sliding cylinder is connected with a screw rod in a threaded manner, a spring is fixedly arranged at the rear end of the screw rod, the rear end of the spring is fixedly connected with a T-shaped circular sliding block, the T-shaped circular sliding block is arranged in the T-shaped circular sliding groove in a sliding manner, and the T-shaped circular sliding block is arranged on the front side wall of the chalk mounting seat.

Preferably, the first switch and the second switch are respectively in a circle drawing mode and an ellipse drawing mode, and both the first switch and the second switch are button switches.

Preferably, an intelligent control module and a storage battery are fixedly mounted in the mounting seat, a charging socket is fixedly mounted on the top side wall of the mounting seat, and the type of the charging socket is a USB-C port.

Preferably, the left side of two rectangular spouts is located the preceding lateral wall of rotatory rectangular board and all is provided with centimetre scale mark, and the scale initial point of two centimetre scale marks is the centre of a circle department of annular outer rail.

Preferably, charging socket's output is connected with the input electricity of battery, the output of battery is connected with intelligent control module's input electricity, intelligent control module's output is connected with the input electricity of servo motor, double-shaft motor and display screen, the output of switch one, switch two and digital button key is connected with intelligent control module's input electricity.

(III) advantageous effects

The invention has the beneficial effects that:

1. this automatic drawing device is used in mathematical education, through the rotatory rectangular board that sets up in the annular outer rail, when servo motor's output shaft drives rotatory rectangular board when annular outer rail internal rotation, and then can realize driving two slide cartridges and be the annular motion, the chalk of centre gripping can be along with the rotatory one hundred eighty degrees of drum two semicircle lines of drawing on the chalk mount pad in two slide cartridges this moment, two semicircle lines just can form a circular, and then can realize drawing out standard circular on the blackboard, relative and the manual drawing circle of mr, the circular existence deviation that can avoid drawing, lead to the student to understand the deviation etc. that appears, make the student understand etc. more easily.

2. The automatic drawing device for mathematical education can realize the homodromous or reverse sliding of the two sliding cylinders in the two strip chutes through the circular groove formed on the rotary strip plate and the matching of the double-shaft motor, the rotary rod, the spiral threads and the thread cylinders arranged in the circular groove, further can select the diameter when drawing circles or ellipses according to the actual requirement, and can realize that chalks clamped on the chalk mounting seats in the two sliding cylinders can draw two half arcs on a blackboard along with one hundred eighty degrees of rotation of the cylinders under the control of the intelligent control module to control the positive or reverse rotation of the double-shaft motor through the homodromous or reverse sliding of the two sliding cylinders in the two strip chutes, the two half arcs just can form an ellipse, further can realize the drawing of a standard ellipse on the blackboard, and realize that the drawing device can draw a circle and an ellipse, the practicability is improved, the drawing device does not need to be replaced, and the use by teachers is facilitated.

3. The automatic drawing device for the mathematical education is characterized in that a sliding barrel, a thread groove, a screw rod, a spring, a T-shaped circular sliding block, a T-shaped circular sliding groove, a chalk mounting seat, a mounting groove and an extrusion pad are arranged in a matched mode, chalk can be mounted in the chalk mounting seat through the rear end of the sliding barrel, the chalk can be mounted and fixed through the chalk mounting seat, then a small section of the rear end of the chalk can be exposed by rotating the screw rod to facilitate drawing operation, the chalk can be in close contact with a blackboard under the pushing of the spring, the situation that drawing is unclear can be avoided, the screw rod can be rotated again after the small section of the chalk is used up, the screw rod is screwed into the sliding barrel to continuously push out the small section of the rear end of the chalk, the rear end of the chalk can be in contact with the blackboard, meanwhile, the chalk can be protected, the sliding barrel at the exposed part of the longer part of the chalk can be prevented from being broken and the like, can avoid causing the use experience not good etc..

Drawings

FIG. 1 is a schematic front view of the present invention;

FIG. 2 is a schematic left-side view of a partial cross-sectional structure of the present invention;

FIG. 3 is a front sectional view of the rotating strip plate of the present invention;

FIG. 4 is a front view of a partial cross-sectional structure of a rotating strip plate according to the present invention;

FIG. 5 is a schematic perspective partial cross-sectional view of a slide cartridge according to the present invention;

FIG. 6 is a schematic top view of the present invention;

FIG. 7 is a schematic top sectional view of a chalk holder according to the present invention;

fig. 8 is a front view of the mounting base of the present invention.

In the figure: 1 annular outer rail, 2 annular racks, 3L-shaped supporting rods, 4 mounting seats, 5 handles, 6 servo motors, 7 rotating strip plates, 8 gear grooves, 9 gears, 10 strip sliding grooves, 11 sliding cylinders, 12 threaded grooves, 13 threaded rods, 14 springs, 15T-shaped circular sliding blocks, 16T-shaped circular sliding grooves, 17 chalk mounting seats, 18 mounting grooves, 19 extrusion pads, 20 chalks, 21 intelligent control modules, 22 switch I, 23 switch II, 24 display screens, 25 digital button keys, 26 circular grooves, 27 double-shaft motors, 28 rotating rods, 29 spiral threads, 30 threaded cylinders, 31 storage batteries, 32 charging sockets and 33 cm scale marks.

Detailed Description

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 only a part of the embodiments of the present invention, and not all of the 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 invention.

As shown in fig. 1 to 8, the present invention provides a technical solution: an automatic drawing device for mathematics teaching comprises an annular outer rail 1, wherein the annular outer rail 1 can be attached to a blackboard, so that the device can be conveniently attached to the blackboard for drawing operation, an annular rack 2 is fixedly arranged on the inner wall of the annular outer rail 1, L-shaped support rods 3 are fixedly arranged at the left end and the right end of the front side wall of the annular outer rail 1, mounting seats 4 are fixedly arranged at the opposite sides of the two L-shaped support rods 3, the mounting seats 4 are connected with the annular outer rail 1 through the two L-shaped support rods 3 to form an integral frame of the device and support a plurality of parts of the device, meanwhile, the L-shaped support rods 3 can not only play a role in connecting the annular outer rail 1 and the mounting seats 4, but also set the L-shaped support rods 3 into an L shape and cannot block a rotating sliding barrel 11, so that the normal use of the drawing device can be ensured, a servo motor 6 is fixedly arranged at the rear side of the mounting seats 4, an output shaft of the servo motor 6 can drive the rotary strip plate 6 to rotate, so that chalks 20 on the rear sides of two cylinders 11 on the rotary strip plate 6 can draw lines on a blackboard, the rotary strip plate 7 is fixedly arranged on the output shaft of the servo motor 6, strip sliding grooves 10 are respectively formed in the upper side and the lower side of the rotary strip plate 7, sliding cylinders 11 are respectively arranged in the two strip sliding grooves 10 in a sliding manner, the sliding cylinders 11 can stably slide through the strip sliding grooves 10, the two sliding cylinders 11 can slide in the two strip sliding grooves 10 in the same direction or in opposite directions through circular grooves 26 formed in the rotary strip plate 7, and through the matching of a double-shaft motor 27, a rotating rod 28, spiral threads 29 and a threaded cylinder 30 which are arranged in the circular grooves 26, so that the diameters of circles or ellipses can be selected according to actual requirements, a first switch 22 and a second switch 23 are respectively arranged on the left side and the right side of the front side wall of, the upper side and the lower side of the front side wall of the mounting seat 4 are respectively provided with a display screen 24 and a digital button key 25, the display screen 24 can display input diameter data when drawing a circle or an ellipse, the right side of the inside of the rotary strip plate 7 is provided with a circular groove 26, the left side of the circular groove 26 is communicated with the two strip chutes 10, the middle part of the inside of the circular groove 26 is fixedly provided with a double-shaft motor 27, two output shafts of the double-shaft motor 27 are fixedly provided with rotary rods 28, the parts of the two rotary rods 28 corresponding to the two strip chutes 10 are respectively provided with a spiral thread 29, the parts of the two rotary rods 28 provided with the spiral threads 29 are respectively in threaded connection with a thread cylinder 30, the left side walls of the two thread cylinders 30 are respectively in fixed connection with the two slide cylinders 11 through connecting blocks, the two output shafts of the double-shaft motor 27 can drive the two rotary rods 28 to rotate, the two rotary rods 28 are in threaded connection with the thread cylinders 30 through, further, the distance between the two cylinders 11 can be adjusted to be equal to the diameter and length of the circle or the ellipse to be drawn by approaching or separating the two threaded cylinders 30 to each other, and the diameter of the circle or the ellipse to be drawn can be selected according to actual requirements.

The front side bottom end of mount pad 4 is fixed and is provided with handle 5, and the arc recess has been seted up to the rear side wall of handle 5, makes things convenient for the hand to grip through the handle 5 that sets up, and then conveniently carries out the drawing operation with the rear side wall of annular outer rail 1 and blackboard laminating, and the arc recess can increase hand and 5 friction of handle, can avoid taking place to slide etc..

Gear grooves 8 have all been seted up at the upper and lower both ends of rotatory rectangular board 7, all install gear 9 in two gear grooves 8, and two gear 9 all with the meshing of annular rack 2, through the meshing of gear 8 and the annular rack 2 that sets up, stability more when can making rotatory rectangular board 7 along with servo motor 6's output shaft is rotatory.

A screw 13 is connected with the inner thread of a thread groove 12 arranged on the front side wall of the sliding barrel 11, a spring 14 is fixedly arranged at the rear end of the screw 13, the rear end of the spring 14 is fixedly connected with a T-shaped circular sliding block 15, the T-shaped circular sliding block 15 is arranged in a T-shaped circular sliding groove 16 in a sliding manner, the T-shaped circular sliding block 16 is arranged on the front side wall of a chalk mounting seat 17, the screw 13 can be screwed into the sliding barrel 11 by rotating the screw 13, at the moment, the rear end of the chalk 20 can be exposed to a small section to facilitate drawing operation, the chalk 20 can be in close contact with the blackboard under the pushing of the spring 14, the situation that the drawing is not clear can be avoided, the screw 13 can be rotated again after the exposed small section of the chalk 20 is used up, the screw 13 is screwed into the sliding barrel 11 to push the rear end of the chalk 20 out of the small section continuously, and then the rear end of the chalk 20 can be kept in contact with, and further, the chalk 20 can be well protected, and the phenomenon that the chalk 20 is broken when drawing can be avoided.

Mounting groove 18 has been seted up to the rear side wall of chalk mount pad 17, and the lateral wall of mounting groove 18 is fixed and is provided with extrusion pad 19, is provided with chalk 20 in the mounting groove 18, can insert the one end of chalk 20 through the mounting groove 18 that sets up, realizes fixed the centre gripping of chalk 20, and can avoid chalk 20 to take place to drop etc. through the extrusion pad 19 that sets up, can guarantee that the firm centre gripping of chalk 20 is fixed in mounting groove 18.

The first switch 22 and the second switch 23 are respectively in a circle drawing mode and an ellipse drawing mode, the first switch 22 and the second switch 23 are both button switches, and the first switch 22 and the second switch 23 are respectively in the circle drawing mode and the ellipse drawing mode, so that different commands for drawing circles or ellipses can be sent by the intelligent control module 21 after the first switch 22 and the second switch 23 are pressed, and the operation of drawing circles or ellipses is further realized.

An intelligent control module 21 and a storage battery 31 are fixedly installed in the installation seat 4, a charging socket 32 is fixedly installed on the top side wall of the installation seat 4, the type of the charging socket 32 is a USB-C port, and the storage battery 31 can be charged conveniently by setting the charging socket 32 to be the type of the USB-C port which is a common type.

The left side of two rectangular spouts 10 is located the preceding lateral wall of rotatory rectangular board 7 and all is provided with centimetre scale mark 33, and the scale initial point of two centimetre scale marks 33 is the centre of a circle department of annular outer rail 1, diameter when being convenient for observe the drawing through the centimetre scale mark 33 that sets up etc. simultaneously all sets up the initial point of two centimetre scale marks 33 in the centre of a circle department of annular outer rail 1, can make the scale interval on the centimetre scale mark 33 and the circle or the oval diameter adaptation of drawing.

The output end of the charging socket 32 is electrically connected with the input end of the storage battery 31, the output end of the storage battery 31 is electrically connected with the input end of the intelligent control module 21, the output end of the intelligent control module 21 is electrically connected with the input ends of the servo motor 6, the double-shaft motor 27 and the display screen 24, and the output ends of the first switch 22, the second switch 23 and the digital button keys 25 are electrically connected with the input end of the intelligent control module 21.

The method comprises the following operation steps:

s1, when in use, the drawing device is picked up by holding the handle 5, the rear side wall of the annular outer rail 1 is contacted with a blackboard, when a circle needs to be drawn, the diameter of the circle needs to be drawn can be input by pressing the digital button key 25, the input diameter can be displayed through the display screen 24, then the first switch 22 can be pressed by a thumb, the first switch 22 transmits a signal to the intelligent control module 21, the intelligent control module 21 can control the operation of the double-shaft motor 27, then the two output shafts of the double-shaft motor 27 can drive the two rotating rods 28 to rotate, at the moment, the rotating rods 28 are connected with the threads of the thread cylinders 30 through the spiral threads 29, the two thread cylinders 30 can be driven to mutually approach or separate in the circular groove 26, the distance between the two cylinders 11 can be adjusted to the diameter length of the circle needed to be drawn, then the intelligent control module 21 can control the operation of the servo motor 6, and the output shaft of the servo motor 6 can rotate one, the chalk clamped on the chalk mounting seats 17 in the two sliding cylinders can draw two semicircular lines on the blackboard along with the one hundred eighty degrees rotation of the cylinder 11 at the moment, and then the two semicircular lines are drawn on the blackboard along with the one hundred eighty degrees rotation of the cylinder 11 at the moment, and the two semicircular lines just can form a circle at the moment, so that the standard circle can be drawn on the blackboard;

s2, when an ellipse needs to be drawn, the long diameter and the short diameter of the ellipse needs to be drawn can be input by pressing the digital button key 25, then the switch II 23 can be pressed by the thumb, the signal is transmitted to the intelligent control module 21 by the switch II 23, the intelligent control module 21 can control the operation of the double-shaft motor 27, then two output shafts of the double-shaft motor 27 can drive the two rotating rods 28 to rotate, at the moment, the rotating rods 28 are in threaded connection with the threaded cylinders 30 through the spiral threads 29, the two threaded cylinders 30 can be driven to mutually approach or separate in the circular grooves 26, further, the distance between the two cylinders 11 can be adjusted to the length of the long diameter of the ellipse needing to be drawn, then the intelligent control module 21 can control the output shaft of the servo motor 6 to firstly rotate ninety degrees, meanwhile, the intelligent control module 21 can control the two output shafts of the double-shaft motor 27 to reversely rotate, and further can drive, when the output shaft of the servo motor 6 drives the rotary strip plate 7 to rotate at ninety degrees first, the two cylinders 11 are just close to the position where the distance is equal to the short diameter of the ellipse to be drawn, then the output shaft of the servo motor 6 continues to rotate at ninety degrees, and simultaneously the two output shafts of the double-shaft motor 27 rotate in opposite directions to drive the two cylinders 11 to be away from each other until the distance is equal to the long diameter of the ellipse to be slid out, the chalks 20 on the rear sides of the two cylinders 11 can just draw two semiellipses on the blackboard, the step is repeated in opposite directions, two semielliptical lines are drawn on the blackboard again, and the two semielliptical lines can just form an ellipse with the long diameter and the semidiameter being just equal to the input length data;

s3, the chalk 20 can be installed in the chalk installation seat 17 through the rear end of the sliding barrel 11, the chalk 20 can be installed and fixed through the chalk installation seat 17, then the screw 13 is rotated to enable the screw 13 to be screwed into the sliding barrel 11, at the moment, the rear end of the chalk 20 is exposed to a small section to facilitate drawing operation, the chalk 20 can be in close contact with a blackboard under the pushing of the spring 14, the situation that drawing is not clear can be avoided, when the exposed small section of the chalk 20 is used up, the screw 13 can be rotated again, the screw 13 is screwed into the sliding barrel 11 to enable the rear end of the chalk 20 to be pushed out to the small section continuously, the rear end of the chalk 20 can be kept in contact with the blackboard, and the rest can be done until the chalk 20 is used up.

The above-mentioned embodiments, objects, technical solutions and advantages of the present invention are further described in detail, it should be understood that the above-mentioned embodiments are only illustrative of the present invention and are not intended to limit the present invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the protection scope of the present invention.