A clamp-type blackboard writing aid for teaching

Abstract

The present invention discloses a clamp-based teaching blackboard writing auxiliary device. The auxiliary device includes a fixed shell, a side of the fixed shell away from the cover plate is fixedly connected to a load-bearing plate, a side of the load-bearing plate close to the cover plate is provided with a holding groove for placing chalk, a push plate is slidably connected in the fixed shell, a thrust spring is fixedly connected between the push plate and the fixed shell, a limit assembly is provided on the fixed shell through the sliding of a vertical rod, the limit assembly is provided with a first clamping plate, the sliding groove is fixedly connected to a connecting rod through the sliding plate, and the connecting rod is fixedly connected to a second clamping plate symmetrical to the first clamping plate. The present invention utilizes a first ratchet and a limit card plate to intermittently move the limit cone upward, adjusts the distance between the first clamping plate and the second clamping plate, and intermittently extends the chalk, thereby achieving the purpose of adjusting the extension amount of the chalk, and at the same time utilizes the second ratchet and the ratchet bar to cooperate to prevent the chalk from retracting during the writing process, and utilizes the fixed shell to prevent the hand from directly contacting the chalk.

Description

Technical Field

[0001] The present invention relates to the technical field of teaching tools, and in particular to a clamping-based teaching blackboard writing auxiliary device. Background Art

[0002] The main components of chalk are calcium carbonate and calcium sulfate. If the hand holds the chalk for a long time to write, the calcium sulfate in the chalk will burn the skin of the hand. When using the chalk, the chalk will be stuck in the card holder, and the chalk will be written by holding the card holder. As the length of the chalk is gradually shortened as it is used, the card holder needs to be released to fix the chalk again and adjust the extension of the chalk. The adjustment operation of the extension of the chalk in this process is cumbersome and inconvenient, resulting in a waste of time and affecting the efficiency of writing. Summary of the invention

[0003] The present invention provides a clamping-based teaching blackboard writing auxiliary device to solve the problems raised in the background technology.

[0004] In order to achieve the above object, the present invention adopts the following technical scheme:

[0005] A clamping-based teaching blackboard auxiliary device comprises a fixed shell, the fixed shell is rotatably connected with a cover plate, a torsion spring is fixedly connected between the cover plate and the fixed shell, a bearing plate is fixedly connected to the side of the fixed shell away from the cover plate, a holding groove for placing chalk is arranged on the side of the bearing plate close to the cover plate, a push plate is slidably connected in the fixed shell, a thrust spring is fixedly connected between the push plate and the fixed shell, a sliding groove connected to the holding groove is arranged on the bearing plate, a transmission gear is rotatably connected in the sliding groove, a limit assembly is arranged on the fixed shell through a vertical rod sliding, the limit assembly is provided with a first clamping plate, the sliding groove is fixedly connected with a connecting rod through the sliding plate, and the connecting rod is fixed A second clamping plate symmetrical to the first clamping plate is connected, the limiting assembly and the connecting rod are both provided with a toothed plate meshing with the transmission gear, elastic protrusions for increasing friction are equidistantly distributed on the opposite sides of the first clamping plate and the second clamping plate, a fixing frame is fixedly connected to the top of the fixed shell, the fixing frame is rotatably connected to a swinging plate, a torsion spring is fixedly connected between the swinging plate and the fixing frame, a pressing rod for pushing the swinging plate to rotate is slidably connected to the fixed shell, a first pawl is rotatably connected to the side of the swinging plate away from the pressing rod, a torsion spring is fixedly connected between the first pawl and the swinging plate, and the limiting assembly changes the distance between the first clamping plate and the second clamping plate through the pressing rod to release the chalk.

[0006] Furthermore, the limiting assembly includes a fixed rod, which is slidably connected to the vertical rod of the fixed shell, a spring is fixed between the fixed rod and the fixed shell, the lower end of the fixed rod is fixed to the first clamping plate, the upper part of the fixed rod is fixed to the limiting block, and the fixed rod located between the first clamping plate and the limiting block is equidistantly fixed to the limiting cone.

[0007] Furthermore, the fixing frame is slidably connected to a limit rod, a spring is fixed between the limit rod and the fixing frame, a trapezoidal groove cooperating with the limit rod is provided at the lower part of the pressing rod, the limit rod contacts and cooperates with the limit block to limit the upward movement of the fixing rod.

[0008] Furthermore, the fixed shell is provided with a slide groove, a pressing piece is fixedly connected to the top of the fixed shell, a moving frame fixed to the push plate is slidably connected in the slide groove, the moving frame is slidably connected to a lower pressure frame, the lower pressure frame is fixedly connected to a connecting frame slidably connected to the moving frame, the connecting frame is fixedly connected to a positioning rod slidably matched with the moving frame, a blind hole is provided in the top of the fixed shell, the positioning rod cooperates with the blind hole of the fixed shell, and is used for limiting and fixing the moving frame, and a spring is provided between the moving frame and the connecting frame.

[0009] Furthermore, a mounting frame located between the fixing frame and the slide slot is fixedly connected in the fixing shell, the mounting frame is rotatably connected with a limit clamping plate for limiting downward movement of the fixing rod, and the mounting frame is fixed with a spring sheet for supporting the limit clamping plate.

[0010] Furthermore, a second pawl is symmetrically rotatably connected to the lower part of the movable frame, a torsion spring is fixedly connected to the second pawl and the movable frame, and ratchet bars for limiting the second pawl are fixedly connected to both sides of the slide groove in the fixed shell.

[0011] Furthermore, the upper part of the supporting plate is rotatably connected to a lower pressure plate, a tension spring is fixed between the lower pressure plate and the fixed shell, a protrusion is provided on the side of the lower pressure plate close to the push plate, the lower pressure plate contacts and cooperates with the push plate for the lower pressure plate to swing, the lower pressure plate is fixed with a push rod for pushing the limiting card to swing, the fixed frame is rotatably connected to a swing rod for pushing the first ratchet to swing, and a spring is connected between the swing rod and the fixed frame.

[0012] Furthermore, it also includes sliding rods distributed in the circumferential direction, the sliding rods are slidably connected to the fixed shell, and the sliding rods are fixed with clamping plates for centering chalk.

[0013] Furthermore, it also includes a positioning frame for limiting the position of chalk, the positioning frame is fixedly connected to a side of the push plate away from the thrust spring, and the containing groove is fixedly connected to a baffle for limiting the movement of the positioning frame.

[0014] Furthermore, the axis lines of the first clamping plate, the clamping plate and the positioning frame coincide with each other.

[0015] The present invention has the following advantages:

[0016] As described above, the present invention relates to a clamp-based teaching blackboard writing auxiliary device, which uses a first ratchet and a limiting card plate to intermittently move the limiting cone upward, adjusts the distance between the first clamp and the second clamp, and makes the chalk extend intermittently, so as to adjust the extension amount of the chalk, and uses the second ratchet and the spine to prevent the chalk from retracting during the writing process, and uses a fixed shell to prevent the hand from directly contacting the chalk, so as to protect the hand skin; uses a circumferentially arranged clamping plate to limit the chalk, so as to avoid the chalk shaking off the trajectory during the adjustment of the length of the chalk, causing it to shake during writing, and uses a baffle to limit the positioning frame, so as to remind the personnel to replace the chalk and continue to use it. The teaching blackboard writing auxiliary device described in the present invention makes it easy to adjust the extension amount of the chalk, saves time, and thus improves the efficiency of writing fonts. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the three-dimensional structure of the present invention.

[0018] Figure 2 It is a schematic diagram of the cross-sectional three-dimensional structure of the present invention.

[0019] Figure 3 It is a schematic diagram of the three-dimensional structure of the chalk length adjusting part of the present invention.

[0020] Figure 4 It is a schematic diagram of the three-dimensional structure of the first clamping plate and the second clamping plate of the present invention.

[0021] Figure 5 It is a schematic diagram of the three-dimensional structure of the swing plate, the pressing rod and the first pawl of the present invention.

[0022] Figure 6 It is a schematic diagram of the three-dimensional structure of the limiting component of the present invention.

[0023] Figure 7 It is a schematic diagram of the three-dimensional structure of the pressing member, the movable frame and the lower pressing frame of the present invention.

[0024] Figure 8 It is a schematic diagram of the cross-sectional three-dimensional structure of the mobile frame of the present invention.

[0025] Fig. 9 It is a schematic diagram of the three-dimensional structure of the spine and the clamping plate of the present invention.

[0026] Fig.10 It is a schematic diagram of the three-dimensional structure of the mounting frame, the limiting clamping plate and the spring sheet of the present invention.

[0027] Fig.11 It is a schematic diagram of the three-dimensional structure of the lower pressing plate, the push rod and the swing rod of the present invention.

[0028] Parts names and serial numbers in the figure:

[0029] 1-fixed shell, 2-cover plate, 3-bearing plate, 4-holding groove, 5-push plate, 6-thrust spring, 7-sliding groove, 8-transmission gear, 9-limiting assembly, 91-fixed rod, 92-limiting round table, 93-limiting block;

[0030] 10-first clamping plate, 11-connecting rod, 12-second clamping plate, 13-fixed frame, 14-limiting rod, 15-swinging plate, 16-pressing rod, 17-first ratchet, 18-sliding groove, 19-pressing member, 20-moving frame;

[0031] 21-downward pressing frame, 22-connecting frame, 23-positioning rod, 24-mounting frame, 25-limiting card plate, 26-spring sheet, 27-second pawl, 28-spike strip, 29-downward pressing plate, 30-push rod;

[0032] 31-swing rod, 32-sliding rod, 33-clamping plate, 34-positioning frame, 35-baffle. DETAILED DESCRIPTION

[0033] The preferred technical solutions of the present invention are described in detail below with reference to the accompanying drawings.

[0034] Example 1

[0035] This embodiment 1 describes a clamp-based teaching blackboard writing auxiliary device, such as Figure 1-Figure 11 shown.

[0036] The teaching blackboard writing auxiliary device includes a fixed shell 1, the front part of the fixed shell 1 is rotatably connected with a cover plate 2, a torsion spring is fixedly connected between the cover plate 2 and the fixed shell 1, a bearing plate 3 is installed on the rear part of the fixed shell 1 by bolts, a holding groove 4 for placing chalk is arranged on the front side of the bearing plate 3, a push plate 5 is slidably connected to the bottom of the fixed shell 1, a thrust spring 6 is fixedly connected between the right side of the push plate 5 and the right wall of the fixed shell 1, a sliding groove 7 connected to the holding groove 4 is arranged on the left part of the bearing plate 3, a transmission gear 8 is rotatably connected to the upper part of the sliding groove 7, a limiting assembly 9 is provided on the fixed shell 1 through a vertical rod sliding, the limiting assembly 9 is provided with a first clamping plate 10, the sliding groove 7 is fixedly connected with a connecting rod 11 through the sliding plate, the connecting rod 11 is fixedly connected with a second clamping plate 12, the first clamping plate 10 and the second clamping plate 12 are symmetrical up and down, and are used to limit the chalk, and the push plate 5 is pushed with the thrust spring 6. The chalk in the movable containing groove 4 moves toward the first clamping plate 10, so that the chalk is between the first clamping plate 10 and the second clamping plate 12 and contacts it. The limiting assembly 9 and the connecting rod 11 are both provided with a toothed plate meshing with the transmission gear 8. The first clamping plate 10 and the second clamping plate 12 are equidistantly provided with elastic protrusions for increasing friction force on the opposite sides. A fixing frame 13 is fixedly connected to the top of the fixed shell 1, and the fixing frame 13 is located on the left side of the sliding groove 7. The lower part of the fixing frame 13 is rotatably connected to a swing plate 15, and a torsion spring is fixedly connected between the swing plate 15 and the fixing frame 13. The left part of the upper side surface of the fixed shell 1 is slidably connected to a pressing rod 16 for pushing the swing plate 15 to rotate, and the right part of the swing plate 15 is rotatably connected to a first pawl 17, and a torsion spring is fixedly connected between the first pawl 17 and the swing plate 15. The limiting assembly 9 is changed by the pressing rod 16 to change the distance between the first clamping plate 10 and the second clamping plate 12 for releasing the chalk.

[0037] The limiting assembly 9 includes a fixing rod 91, which is slidably connected to the vertical rod of the fixing shell 1. The vertical rod of the fixing shell 1 is sleeved with a spring fixedly connected to the fixing rod 91 and the fixing shell 1. The lower end of the fixing rod 91 is connected to the first clamping plate 10 by bolts. The upper part of the fixing rod 91 is fixedly connected to the limiting block 93. The fixing rod 91 is equidistantly welded with a limiting cone 92, and the limiting cone 92 is located between the first clamping plate 10 and the limiting block 93.

[0038] The upper part of the fixing frame 13 is slidably connected to the limiting rod 14, and a spring is fixed between the limiting rod 14 and the fixing frame 13. The lower part of the pressing rod 16 is provided with a trapezoidal groove that cooperates with the left end of the limiting rod 14. The right end of the limiting rod 14 contacts and cooperates with the limiting block 93 to limit the upward movement of the fixing rod 91.

[0039] The upper side of the fixed shell 1 is provided with a slide groove 18, and the slide groove 18 is located on the right side of the slide groove 7. A pressing piece 19 is fixedly connected to the upper side of the fixed shell 1, and the pressing piece 19 is located on the right side of the slide groove 18. A moving frame 20 fixedly connected to the push plate 5 is slidably connected in the slide groove 18, and the moving frame 20 is slidably connected with a lower pressing frame 21. The lower pressing frame 21 is fixedly connected to a connecting frame 22 slidably connected to the moving frame 20, and the connecting frame 22 is fixedly connected to a positioning rod 23 slidably matched with the moving frame 20. A blind hole is provided at the top of the fixed shell 1, and the blind hole of the fixed shell 1 is located on the right side of the slide groove 18. The positioning rod 23 cooperates with the blind hole of the fixed shell 1 for limiting and fixing the moving frame 20. Pressing the pressing piece 19 squeezes the lower pressing frame 21, drives the connecting frame 22 to make the positioning rod 23 disengage from the blind hole of the fixed shell 1, and releases the limiting of the moving frame 20 and the push plate 5. A spring is provided between the moving frame 20 and the connecting frame 22, and the spring is sleeved on the outside of the positioning rod 23.

[0040] A mounting frame 24 located between the fixing frame 13 and the slide groove 18 is connected inside the fixing shell 1 by bolts. The mounting frame 24 is rotatably connected to a limiting clamping plate 25. The limiting clamping plate 25 cooperates with the limiting round table 92 to limit the downward movement of the fixing rod 91, so that the adjusted spacing between the first clamping plate 10 and the second clamping plate 12 is maintained. Combined with the thrust spring 6 and the push plate 5, the extension amount of the chalk is controlled. The mounting frame 24 is connected to a spring sheet 26 for supporting the limiting clamping plate 25 by bolts.

[0041] The lower parts of the front and rear walls of the movable frame 20 are rotatably connected with the second pawl 27 , and the second pawl 27 and the movable frame 20 are fixedly connected with a torsion spring. Two ratchet bars 28 for limiting the second pawl 27 are fixedly connected to the top of the fixed shell 1 , and the slide groove 18 is located between the two ratchet bars 28 .

[0042] The upper part of the front side surface of the supporting plate 3 is rotatably connected with a lower pressure plate 29, and the lower pressure plate 29 is located on the right side of the push plate 5. A tension spring is equidistantly fixed between the upper side surface of the lower pressure plate 29 and the top inside the fixed shell 1. A protrusion is provided at the lower part of the lower pressure plate 29, and the protrusion of the lower pressure plate 29 contacts and cooperates with the push plate 5 for the lower pressure plate 29 to swing. The lower pressure plate 29 is connected to a push rod 30 for pushing the limit card plate 25 to swing through bolts. The fixed frame 13 is rotatably connected with a swing rod 31 for pushing the first ratchet 17 to swing, and a spring is connected between the swing rod 31 and the fixed frame 13.

[0043] In addition, the present invention also proposes a method for using the clamp-type teaching blackboard writing auxiliary device, which is implemented based on the clamp-type teaching blackboard writing auxiliary device and specifically includes the following steps:

[0044] In the initial state, the upper end of the positioning rod 23 is located in the blind hole of the fixed shell 1, and the thrust spring 6 is in a compressed state. The user opens the cover 2 and puts the truncated cone-shaped chalk into the containing groove 4. The user presses the pressing piece 19 to squeeze the lower pressing frame 21, driving the connecting frame 22 to make the positioning rod 23 disengage from the blind hole of the fixed shell 1, and releases the limit on the movable frame 20 and the push plate 5. Under the action of the thrust spring 6, the push plate 5 is pushed to drive the chalk in the containing groove 4 to move toward the first clamping plate 10, so that the chalk is between the first clamping plate 10 and the second clamping plate 12 and contacts them. At this time, the limit rod 14 cooperates with the limit block 93 to limit the upward movement of the fixed rod 91. The user holds the fixed shell 1 and moves it to write with the chalk. As the chalk is written, the extension amount of the chalk gradually shortens.

[0045] When adjusting the extension amount of the chalk, the user presses the pressing rod 16 to move downward, and the limiting rod 14 moves to the left into the trapezoidal groove of the pressing rod 16 under the action of the spring on it, releasing the limit on the limiting circular table 92. At the same time, the pressing rod 16 squeezes the left part of the swing plate 15 to swing downward, and the torsion spring of the swing plate 15 is tightened accordingly, and the right part of the swing plate 15 swings upward and pushes the limiting circular table 92 upward through the first ratchet 17. The limiting circular table 92 pushes the left part of the limiting clamping plate 25 to swing upward, and the right part of the limiting clamping plate 25 squeezes the spring sheet 26 downward. After the limiting clamping plate 25 is separated from the limiting circular table 92, the limiting clamping plate 25 is pushed to reset and contact the next limiting circular table 92 for limiting position under the action of the spring sheet 26. The limiting circular table 92 moves upward and drives the first clamping plate 10 to move upward through the fixing rod 91. The first clamping plate 10 moves upward to facilitate The toothed plate and the transmission gear 8 are used to drive the second clamping plate 12 to move downward. At this time, the distance between the first clamping plate 10 and the second clamping plate 12 is enlarged. Under the action of the thrust spring 6, the push plate 5 is pushed to drive the chalk to move out, and the adjustment of the chalk extension amount is completed. The user releases the pressing rod 16, and the swing plate 15 swings and resets under the action of the torsion spring thereon to make the first pawl 17 move downward. Under the action of the torsion spring of the first pawl 17, the first pawl 17 swings and contacts the lower side of the next limiting circular table 92. The swinging reset of the swing plate 15 will push the pressing rod 16 to move upward. The pressing rod 16 moves upward to push the limiting rod 14 to contact and limit the upper side of the limiting circular table 92. Under the action of the spring of the fixing rod 91, the first clamping plate 10 has a tendency to move downward, and the limiting clamping plate 25 cooperates with the limiting circular table 92 to limit the downward movement of the fixing rod 91. As the extension amount of the chalk is gradually adjusted, the push plate 5 and the movable frame 20 are pushed to the left by the thrust spring 6, and the movement of the movable frame 20 drives the parts thereon to move. The second pawl 27 contacts and cooperates with the ratchet bar 28 to limit the push plate 5 from moving right, thereby preventing the chalk from retracting during writing.

[0046] When the chalk needs to be replaced, the user presses down the lower pressure frame 21 to push the second pawl 27 to swing downward, so that the second pawl 27 is disengaged from the ratchet 28 downward, and the user pushes the movable frame 20 to move away from the first clamping plate 10 to restore the movable frame 20 to its initial position. At this time, the positioning rod 23 re-enters the blind hole of the fixed shell 1 to limit the movable frame 20.

[0047] After the movable frame 20 is reset, the protrusion of the lower pressure plate 29 is squeezed, so that the left part of the lower pressure plate 29 swings downward, and the right part of the limiting clamping plate 25 is squeezed through the push rod 30, so that the left part of the limiting clamping plate 25 swings upward to release the limit on the limiting circular table 92. The user presses the pressing rod 16 downward, and the limiting rod 14 moves to the left under the action of the spring thereon to release the limit on the limiting circular table 92. The lower pressure plate 29 swings downward, and the first pawl 17 swings upward away from the limiting circular table 92 through the swing rod 31. The fixed rod 91 pushes the first clamping plate 10 to move and reset under the action of the spring thereon, and the second clamping plate 12 moves and resets accordingly.

[0048] Example 2

[0049] On the basis of Example 1, Figure 4 As shown, it also includes a circumferentially distributed sliding rod 32, the sliding rod 32 is slidably connected to the left part of the fixed shell 1, and the sliding rod 32 is fixedly connected to a clamping plate 33, and the clamping plate 33 is used for centering the chalk.

[0050] like Figure 2 As shown, it also includes a positioning frame 34 for limiting the position of chalk. The positioning frame 34 is connected to the left side of the push plate 5 by bolts. The positioning frame 34 cooperates with the containing groove 4 to limit the position of chalk. The containing groove 4 is fixed with a baffle 35 for limiting the movement of the positioning frame 34. The axis center lines of the first clamping plate 10, the clamping plate 33 and the positioning frame 34 coincide.

[0051] The chalk is centered by the circumferentially distributed clamping plates 33. During the process of adjusting the extension of the chalk, the circumferentially arranged clamping plates 33 and the positioning frames 34 are used to cooperate to keep the center of the chalk unchanged and prevent the trajectory of the chalk from deviating. After the positioning frame 34 moves to the left and contacts the baffle 35, the user replaces the chalk.

[0052] It should be understood that the above description is only for exemplary purposes and is not meant to limit the present invention. Those skilled in the art will appreciate that variations of the present invention will be included within the scope of the claims herein.

Claims

1. A clamp-type teaching blackboard writing auxiliary device, characterized by: The invention comprises a fixed shell (1), the fixed shell (1) is rotatably connected with a cover plate (2), a torsion spring is fixedly connected between the cover plate (2) and the fixed shell (1), a bearing plate (3) is fixedly connected to the side of the fixed shell (1) away from the cover plate (2), a holding groove (4) for placing chalk is arranged on the side of the bearing plate (3) close to the cover plate (2), a push plate (5) is slidably connected to the fixed shell (1), a thrust spring (6) is fixedly connected between the push plate (5) and the fixed shell (1), the bearing plate (3) is provided with a sliding groove (7) connected with the holding groove (4), a transmission gear (8) is rotatably connected in the sliding groove (7), a limit assembly (9) is slidably arranged on the fixed shell (1) through a vertical rod, the limit assembly (9) is provided with a first clamping plate (10), the sliding groove (7) is fixedly connected with a connecting rod (11) through the sliding plate, the connecting rod (11) is fixedly connected with a symmetrical connecting rod (11) with the first clamping plate (10) The second clamping plate (12), the limiting assembly (9) and the connecting rod (11) are all provided with toothed plates meshing with the transmission gear (8), the first clamping plate (10) and the second clamping plate (12) are equidistantly provided with elastic protrusions for increasing friction force on the opposite sides thereof, a fixing frame (13) is fixedly connected to the top of the fixed shell (1), the fixing frame (13) is rotatably connected to a swinging plate (15), a torsion spring is fixedly connected between the swinging plate (15) and the fixing frame (13), the fixed shell (1) is slidably connected to a pressing rod (16) for pushing the swinging plate (15) to rotate, a first ratchet (17) is rotatably connected to the side of the swinging plate (15) away from the pressing rod (16), a torsion spring is fixedly connected between the first ratchet (17) and the swinging plate (15), and the limiting assembly (9) changes the distance between the first clamping plate (10) and the second clamping plate (12) through the pressing rod (16) to release the chalk; The limit assembly (9) comprises a fixed rod (91), the fixed rod (91) is slidably connected to a vertical rod of a fixed shell (1), a spring is fixedly connected between the fixed rod (91) and the fixed shell (1), the lower end of the fixed rod (91) is fixedly connected to a first clamping plate (10), the upper part of the fixed rod (91) is fixedly connected to a limit block (93), and the fixed rod (91) located between the first clamping plate (10) and the limit block (93) is fixedly connected to a limit truncated cone (92) at equal distances.

2. According to claim 1, a clamp-type teaching blackboard writing auxiliary device is characterized by: The fixing frame (13) is slidably connected to a limiting rod (14), a spring is fixedly connected between the limiting rod (14) and the fixing frame (13), a trapezoidal groove matching with the limiting rod (14) is arranged at the lower part of the pressing rod (16), and the limiting rod (14) contacts and matches with the limiting block (93) to limit the upward movement of the fixing rod (91).

3. The clamp-type teaching blackboard writing auxiliary device according to claim 1 is characterized in that: The fixed shell (1) is provided with a slide groove (18), a pressing piece (19) is fixedly connected to the top of the fixed shell (1), a moving frame (20) fixedly connected to the push plate (5) is slidably connected in the slide groove (18), the moving frame (20) is slidably connected to a lower pressing frame (21), the lower pressing frame (21) is fixedly connected to a connecting frame (22) slidably connected to the moving frame (20), the connecting frame (22) is fixedly connected to a positioning rod (23) slidably matched with the moving frame (20), a blind hole is provided in the top of the fixed shell (1), the positioning rod (23) matches with the blind hole of the fixed shell (1) and is used for limiting and fixing the moving frame (20), and a spring is provided between the moving frame (20) and the connecting frame (22).

4. The clamp-type teaching blackboard writing auxiliary device according to claim 3 is characterized by: A mounting frame (24) located between the fixing frame (13) and the slide groove (18) is fixedly connected in the fixing shell (1), the mounting frame (24) is rotatably connected to a limiting clamping plate (25) for limiting the downward movement of the fixing rod (91), and the mounting frame (24) is fixedly connected to a spring sheet (26) for supporting the limiting clamping plate (25).

5. The clamp-type teaching blackboard writing auxiliary device according to claim 4 is characterized in that: The lower part of the movable frame (20) is symmetrically rotatably connected with a second pawl (27), the second pawl (27) and the movable frame (20) are fixedly connected with a torsion spring, and ratchet bars (28) for limiting the second pawl (27) are fixedly connected to both sides of the sliding groove (18) in the fixed shell (1).

6. The clamp-type teaching blackboard writing auxiliary device according to claim 4 is characterized in that: The upper part of the bearing plate (3) is rotatably connected to a lower pressure plate (29), a tension spring is fixedly connected between the lower pressure plate (29) and the fixed shell (1), a convex block is arranged on one side of the lower pressure plate (29) close to the push plate (5), the lower pressure plate (29) contacts and cooperates with the push plate (5) for swinging the lower pressure plate (29), the lower pressure plate (29) is fixedly connected to a push rod (30) for pushing the limit clamping plate (25) to swing, the fixed frame (13) is rotatably connected to a swing rod (31) for pushing the first ratchet (17) to swing, and a spring is connected between the swing rod (31) and the fixed frame (13).

7. The clamp-type teaching blackboard writing auxiliary device according to claim 1 is characterized by: It also comprises sliding rods (32) distributed in the circumferential direction, the sliding rods (32) are slidably connected to the fixed shell (1), and the sliding rods (32) are fixedly connected with a clamping plate (33) for centering chalk.

8. The clamp-type teaching blackboard writing auxiliary device according to claim 7 is characterized in that: It also includes a positioning frame (34) for limiting the position of chalk. The positioning frame (34) is fixedly connected to a side of the push plate (5) away from the thrust spring (6). The containing groove (4) is fixedly connected to a baffle (35) for limiting the movement of the positioning frame (34).

9. The clamp-type teaching blackboard writing auxiliary device according to claim 8 is characterized in that: The axis centers of the first clamping plate (10), the clamping plate (33) and the positioning frame (34) coincide with each other.

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