Auxiliary device for drawing circle

Abstract

The invention relates to a circle drawing auxiliary device which comprises a base, a base rod with one end fixedly connected to the base, a center rod perpendicular to the base rod and with the middle end rotationally connected to the other end of the base rod, a driving assembly installed on the base rod and with the driving end in transmission connection to the upper end of the center rod, and at least one circle drawing mechanism. The circle drawing mechanism comprises a straight ruler plate parallel to the base rod, one end of the straight ruler plate is fixedly connected to the lower end of the center rod, the clamping cylinder is slidably connected to the straight ruler plate in the length direction of the straight ruler plate, the second limiting rod is connected to the straight ruler plate in a threaded mode, and the clamping cylinder is of a lower opening structure and used for allowing chalk to be inserted. The end of the second limiting rod abuts against the clamping cylinder. The problems that in the prior art, a circle drawing mode has limitation, a circle is difficult to draw at the high position of a blackboard, and circle drawing is possibly incomplete and has radius changes can be solved.

Description

Technical Field

[0001] The present invention relates to the technical field of teaching aids, and particularly to a circle-drawing assisting device. Background Art

[0002] In teaching activities, teachers will draw circles on the blackboard fixed against the wall for teaching demonstrations. Usually, teachers will draw circles manually or by combining a ruler and a compass. Both circle-drawing methods have the following problems:

[0003] 1. It is difficult for a standing teacher to draw circles at higher positions on the blackboard, and the height is insufficient.

[0004] 2. Phenomena such as incomplete circles and radius changes may occur when drawing circles. For example, when drawing circles manually, it is difficult to keep the radius consistent. When using a compass, it is difficult to make the compass rotate one full circle in one movement, and excessive force will cause the radius between the leg and the center leg to expand. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a circle-drawing assisting device to improve the limitations of the existing circle-drawing methods, which are difficult to draw circles at higher positions on the blackboard, and the drawn circles may be incomplete or have radius changes.

[0006] The present invention is realized through the following technical solutions:

[0007] A circle-drawing assisting device includes a base, a base rod with one end fixedly connected to the base, a center rod perpendicular to the base rod and rotatably connected to the other end of the base rod at the middle, a driving component installed on the base rod and with its driving end drivingly connected to the upper end of the center rod, and at least one set of circle-drawing mechanisms. The circle-drawing mechanism includes a ruler plate parallel to the base rod and with one end fixedly connected to the lower end of the center rod, a clamping cylinder slidably connected to the ruler plate along the length direction of the ruler plate, and a second limiting rod threadedly connected to the ruler plate. The clamping cylinder has a lower opening structure for inserting chalk, and the end of the second limiting rod abuts against the clamping cylinder.

[0008] Further, the base rod includes a fixed rod with one end fixedly connected to the base, an extension rod with one end detachably connected to the other end of the fixed rod, and a sliding sleeve slidably connected to the extension rod along the length direction of the extension rod. The extension rod is parallel to the fixed rod, and the middle end of the center rod is rotatably connected to the sliding sleeve. The driving component is installed on the extension rod.

[0009] Further, a pressure application hole is formed in the upper side of the sliding sleeve, a rotation hole coaxial with the pressure application hole is formed through the bottom of the pressure application hole, the side wall of the central rod abuts against the hole wall of the rotation hole, and the central rod is fixedly connected with a central plate rotatably connected in the pressure application hole; the base rod further includes a pressure application sleeve and a spring both sleeved on the central rod, the pressure application sleeve is threadedly connected to the sliding sleeve through the pressure application hole and abuts against the upper side of the central plate, the upper end of the spring abuts against the lower side of the central plate, and the lower end abuts against the bottom of the pressure application hole.

[0010] Further, at least three first balls located on the same circumference are rotatably connected to the upper side of the central plate, and a first annular groove coaxial with the central rod is formed in the lower side of the pressure application sleeve, and the spherical surfaces of the first balls abut against the first annular groove.

[0011] Further, a second annular groove is coaxially formed in the bottom of the pressure application hole, a third annular groove is coaxially formed in the bottom of the second annular groove, at least three second balls circumferentially and uniformly distributed are rotatably connected to the third annular groove, a bottom ring is also rotatably connected to the second annular groove, the lower end of the bottom ring abuts against the spherical surfaces of the second balls at the same time, and the lower end of the spring abuts against the bottom ring.

[0012] Further, the clamping cylinder includes a transverse slider slidably connected to the straight ruler plate, a fixed cylinder with a lower opening structure and an upper end fixedly connected to the transverse slider, and an elastic clamping cylinder installed in the fixed cylinder for clamping chalk.

[0013] Further, the clamping cylinder further includes a linear driving member installed in the fixed cylinder, a placement plate fixedly connected to the driving end of the linear driving member on the upper side, and a pressure sensor installed on the lower side of the placement plate. The pressure sensor is communicatively connected to the linear driving member, and the elastic clamping cylinder is installed on the lower side of the pressure sensor.

[0014] Further, the clamping cylinder further includes an elastic clamping sleeve fixedly connected to the inner wall of the opening end of the fixed cylinder for clamping chalk.

[0015] Further, at least two sets of circle drawing mechanisms are provided, and each circle drawing mechanism is circumferentially and evenly distributed around the central rod.

[0016] Further, the driving assembly includes a toothed plate slidably connected to the base rod in the length direction and a gear meshing with the toothed plate. The gear is coaxially and fixedly connected to the upper end of the central rod.

[0017] The beneficial effects of the present invention are as follows:

[0018] The circle-drawing assisting device is provided with a base and a base rod installed on the base and forming a cantilever structure. The user only needs to press the base against the lower end of the blackboard, and then drive the clamping cylinder to rotate through the driving component to complete the circle-drawing operation, which improves the problem that it is difficult for a standing teacher in the prior art to draw a circle at a higher position on the blackboard due to insufficient height. Moreover, under the indirect drive of the central rod, the clamping cylinder continuously makes a circular motion, which can maintain the continuity of the circle-drawing operation and can improve the problems such as incomplete circle-drawing and radius change that may occur in the prior art.

[0019] Other advantages, objects and features of the present invention will be described to some extent in the subsequent specification, and to some extent, will be obvious to those skilled in the art based on the study of the following text, or can be taught from the practice of the present invention. The objects and other advantages of the present invention can be realized and obtained through the following specification. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Is an isometric view of the present invention;

[0021] Figure 2 Is a partial structural schematic diagram of the present invention;

[0022] Figure 3 Is of the present invention Figure 2 Partial enlarged view of A therein;

[0023] Figure 4 Is a partial cross-sectional view of the present invention from the first perspective;

[0024] Figure 5 Is a partial cross-sectional view of the present invention from the second perspective;

[0025] Figure 6 Is of the present invention Figure 5 Partial enlarged view of B therein;

[0026] Figure 7 Is a partial cross-sectional view of the circle-drawing mechanism of the present invention.

[0027] In the figure: 1. Base; 11. First suction cup; 12. Handle; 2. Base rod; 21. Fixed rod; 22. Extension rod; 221. Slide hole; 222. Card slot; 223. First threaded hole; 23. Slide sleeve; 231. Pressure application hole; 232. Rotation hole; 233. Second annular groove; 234. Third annular groove; 235. Second ball; 236. Bottom ring; 237. Clamping block; 238. Intermediate jack; 24. Pressure application sleeve; 241. First annular groove; 25. Spring; 26. Connecting bolt; 27. First limiting rod; 28. Support rod; 3. Central rod; 31. Central plate; 311. First ball; 312. Central jack; 32. Extension cylinder; 33. Second suction cup; 4. Driving assembly; 41. Rack; 42. Gear; 5. Straight ruler plate; 51. Slide groove; 52. Second threaded hole; 6. Clamping cylinder; 61. Horizontal slider; 62. Fixed cylinder; 63. Elastic clamping cylinder; 631. Top plate; 632. Reed; 64. Linear drive; 65. Object placing plate; 66. Pressure sensor; 67. Elastic clamping sleeve; 68. Control switch; 7. Second limiting rod; 8. Chalk. Detailed implementation manners

[0028] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some but not all of the embodiments of the present invention. Usually, the components of the embodiments of the present invention described and illustrated in the accompanying drawings here can be arranged and designed in various different configurations.

[0029] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed present invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0030] It should be noted that: Similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0031] In the above description of the present invention, it should be noted that the orientation or positional relationship indicated by terms such as "one side", "the other side", etc. is the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of the present invention is usually placed during use. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be construed as a limitation of the present invention. In addition, terms such as "first", "second", etc. are only used for descriptive distinction and cannot be understood as indicating or implying relative importance.

[0032] In addition, terms such as "identical" do not require the components to be absolutely identical, but there can be minor differences. The term "vertical" only means that the positional relationship between components is more vertical relative to "parallel", and does not mean that the structure must be completely vertical, but can be slightly inclined.

[0033] Please refer to Figures 1-3 , the present invention provides a technical solution: a circle-drawing assisting device, including a base 1, a base rod 2 fixedly connected to one end of the base 1, a central rod 3 perpendicular to the base rod 2 and rotatably connected to the other end of the base rod 2 at the middle end, a driving assembly 4 installed on the base rod 2 and having a driving end drivingly connected to the upper end of the central rod 3, and at least one set of circle-drawing mechanisms. The circle-drawing mechanism includes a straight ruler plate 5 parallel to the base rod 2 and fixedly connected to the lower end of the central rod 3 at one end, a clamping cylinder 6 slidably connected to the straight ruler plate 5 along the length direction of the straight ruler plate 5, and a second limiting rod 7 threadedly connected to the straight ruler plate 5. The clamping cylinder 6 has a lower opening structure for inserting a chalk 8, and the end of the second limiting rod 7 abuts against the clamping cylinder 6.

[0034] During use, first move the clamping cylinder 6 as needed so that it slides on the straight ruler plate 5 until it slides to a position where the distance from the central rod 3 is the required radius. Then, by tightening the second limiting rod 7, the second limiting rod 7 abuts against the clamping cylinder 6 to prevent the clamping cylinder 6 from sliding relative to the straight ruler plate 5. Then, insert the chalk 8 into the clamping cylinder 6. After that, the teacher holds the base 1 and places the base 1 at the lower end position of the blackboard, and moves the base 1 until the central rod 3 reaches the center of the circle at the specified position. At this time, the clamping cylinder 6 holding the chalk 8 is located on the circumference of the circle to be drawn. Finally, the driving assembly 4 can be used to drive the central rod 3 to rotate, and the rotating central rod 3 drives the circle-drawing mechanism to rotate, so that the chalk inserted into the clamping cylinder 6 makes a circular motion on the blackboard to complete the circle-drawing operation.

[0035] Through the above circle-drawing method, the teacher only needs to keep pressing the base 1 at the lower end position of the blackboard, and then can complete the circle-drawing operation by driving the driving assembly 4, which improves the problem that it is difficult for a standing teacher in the prior art to draw a circle at a higher position on the blackboard due to insufficient height. Moreover, under the indirect drive of the central rod 3, the clamping cylinder 6 continuously makes a circular motion, which can maintain the continuity of the circle-drawing operation and can improve the problems of incomplete circle-drawing and radius change that may occur in the prior art.

[0036] It should be noted that the lower side of the clamping cylinder 6 is higher than the lower side of the base 1, so that after the chalk 8 is inserted into the clamping cylinder 6, the chalk 8 can extend out of the clamping cylinder 6 for circle-drawing operation.

[0037] Among them, at least three first suction cups 11 are fixedly connected to the lower side of the base 1, specifically, there can be three, four, five, six, etc., so as to adsorb on the blackboard through each first suction cup 11, reducing the workload of the user. A handle 12 is fixedly connected to the upper side of the base 1, so as to facilitate the smooth use and movement of the base 1 through the handle 12.

[0038] On the basis of the above embodiment, length scales are engraved on the side surface of the straight ruler plate 5. A sliding groove 51 is opened on the lower side of the straight ruler plate 5, and the upper end (closed end) of the clamping cylinder 6 is adapted to and slidably connected to the sliding groove 51 to realize the sliding installation of the clamping cylinder 6, and the cross section of the sliding groove 51 is in a stepped shape or a dovetail shape to prevent the clamping cylinder 6 from detaching from the straight ruler plate 5.

[0039] A plurality of second threaded holes 52 are penetrated and opened on the other side surface of the straight ruler plate 5, and the second limiting rods 7 are threadedly connected to the straight ruler plate 5 through the second threaded holes 52 to abut against the moved clamping cylinder 6, preventing the clamping cylinder 6 from moving and maintaining the drawing circle radius.

[0040] Please refer to Figures 2-4 , in this embodiment: The base rod 2 includes a fixed rod 21 fixedly connected to one end of the base 1, an extension rod 22 detachably connected to the other end of the fixed rod 21, and a sliding sleeve 23 slidably connected to the extension rod 22 along the length direction of the extension rod 22. The extension rod 22 is parallel to the fixed rod 21, and the middle end of the central rod 3 is rotatably connected to the sliding sleeve 23, and the driving assembly 4 is installed on the extension rod 22.

[0041] Before drawing a circle, the distance between the sliding sleeve 23 and the base 1 can be changed by sliding the sliding sleeve 23 relative to the extension rod 22, so as to change the position of the drawn circle relative to the base 1 and realize drawing circles at different positions along the length direction of the base rod 2. Moreover, in this embodiment, one end of the extension rod 22 is detachably connected to the fixed rod 21, so that the extension rod 22 can be detached. At this time, the extension rod 22, the driving assembly 4, the sliding sleeve 23, the central rod 3 and the circle drawing mechanism can be used as a whole for drawing circles, improving convenience.

[0042] Among them, the base rod 2 further includes a plurality of connecting bolts 26, and each connecting bolt 26 is connected to both the fixed rod 21 and the extension rod 22 at the same time to realize the detachable connection between the fixed rod 21 and the extension rod 22.

[0043] A sliding hole 221 is formed through the extension rod 22, and clamping grooves 222 are formed on both inner walls of the sliding hole 221. The sliding sleeve 23 is fixedly connected with two clamping blocks 237 respectively adapted to and slidably connected to the two clamping grooves 222. The stable sliding installation between the sliding sleeve 23 and the extension rod 22 can be realized through the clamping blocks 237. Moreover, a plurality of first threaded holes 223 are formed in the side wall of the extension rod 22, and the first threaded holes 223 are arranged along the length direction of the extension rod 22 and are all communicated with one of the clamping grooves 222.

[0044] The base rod 2 further includes a first limiting rod 27. The first limiting rod 27 is threadedly connected to the extension rod 22 through the first threaded hole 223, and the first limiting rod 27 abuts against the sliding sleeve 23 to prevent the sliding sleeve 23 from continuously sliding relative to the extension rod 22 and keep the central position formed by the central rod 3 unchanged during the process of drawing a circle. Moreover, during the movement, with the limitation of the first limiting rod 27, the movement is facilitated and the positions of all components are ensured to remain unchanged.

[0045] On the basis of the above embodiment, the lower end of the central rod 3 is threadedly connected with an extension cylinder 32, and the lower end of the extension cylinder 32 is fixedly connected with a second suction cup 33. When the extension rod 22 is removed and the extension rod 22, the driving assembly 4, the sliding sleeve 23, the central rod 3 and the circle drawing mechanism are used as a whole to draw a circle, the second suction cup 33 adsorbs on the blackboard as the center point to improve the stability of drawing a circle. At the same time, the height of the central support point formed by the central rod 3 and the extension cylinder 32 can be changed by rotating the extension cylinder 32 relative to the central rod 3 to ensure that the chalk 8 touches the blackboard.

[0046] Please refer to Figures 2-6 In this embodiment: a pressure application hole 231 is formed in the upper side of the sliding sleeve 23, a rotating hole 232 coaxial with the pressure application hole 231 is formed through the bottom of the pressure application hole 231, the side wall of the central rod 3 abuts against the hole wall of the rotating hole 232, and the central rod 3 is fixedly connected with a central plate 31 rotatably connected in the pressure application hole 231. The base rod 2 further includes a pressure application sleeve 24 and a spring 25 both sleeved on the central rod 3. The pressure application sleeve 24 is threadedly connected to the sliding sleeve 23 through the pressure application hole 231 and abuts against the upper side of the central plate 31, the upper end of the spring 25 abuts against the lower side of the central plate 31, and the lower end abuts against the bottom of the pressure application hole 231.

[0047] When the teacher holds the base 1 and places the base 1 at the lower position of the blackboard and moves the base 1 until the central rod 3 reaches the center of the circle at the specified position, or before that, the spring 25 can be compressed by rotating the pressure application sleeve 24, the pressure application sleeve 24 presses the central rod 3 downward, and the central rod 3 indirectly drives the clamping cylinder 6 clamping the chalk 8 to move downward to ensure that the chalk 8 touches the blackboard. Continuously rotating the pressure application sleeve 24 downward can increase the pressure of the chalk 8 on the blackboard and improve the clarity of drawing a circle.

[0048] Of course, as another usage mode, when the chalk 8 is consumed during the process of drawing a circle, the clamping cylinder 6 clamping the chalk 8 can be indirectly driven to move downward by rotating the pressure sleeve 24 to ensure that the chalk 8 touches the blackboard.

[0049] On the basis of the above embodiment, the sliding sleeve 23 is provided with an intermediate jack 238 that can communicate with any one of the first threaded holes 223, so that the first limiting rod 27 is inserted into the connected first threaded hole 223 and the intermediate jack 238 at the same time, realizing the stable position limitation of the sliding sleeve 23.

[0050] Moreover, the central plate 31 is provided with a central jack 312 that is on the same horizontal plane as the intermediate jack 238. After the circle drawing is completed, when carrying and moving, by inserting the first limiting rod 27 into the connected first threaded hole 223, intermediate jack 238, and central jack 312 at the same time, the central rod 3 is prevented from rotating.

[0051] Please refer to Figures 2-6 In this embodiment: at least three first balls 311 located on the same circumference are rotatably connected to the upper side of the central plate 31, and a first annular groove 241 coaxial with the central rod 3 is provided on the lower side of the pressure sleeve 24, and the spherical surfaces of the first balls 311 are in contact with the first annular groove 241.

[0052] In this embodiment, a distance is formed between the lower side of the pressure sleeve 24 and the upper side of the central plate 31, so that the central plate 31 supports the pressure sleeve 24 through the first balls 311.

[0053] Moreover, the first annular groove 241 is an arc groove to fit the spherical surface of the first ball 311.

[0054] When the pressure sleeve 24 is rotated to press the central plate 31, the first balls 311 roll under the action of friction and roll smoothly in the first annular groove 241 to smoothly rotate the pressure sleeve 24 and reduce friction noise.

[0055] In this embodiment: a second annular groove 233 is coaxially provided at the bottom of the pressure hole 231, a third annular groove 234 is coaxially provided at the bottom of the second annular groove 233, at least three second balls 235 evenly distributed in the circumferential direction are rotatably connected to the third annular groove 234, the second annular groove 233 is also rotatably connected to a bottom ring 236, and the lower end of the bottom ring 236 is in contact with the spherical surfaces of the second balls 235 through a spherical groove, and the lower end of the spring 25 is in contact with the bottom ring 236.

[0056] When the pressure sleeve 24 is rotated to press the central plate 31, the central plate 31 presses the spring 25, the spring 25 compresses and presses the bottom ring 236. At this time, the bottom ring 236 can rotate smoothly under the action of friction, and the second balls 235 achieve rolling friction to reduce friction and friction noise.

[0057] Among them, the second annular groove 233 is a U-shaped groove, and the third annular groove 234 is an arc-shaped groove.

[0058] Please refer to Figures 5-7 , in this embodiment: The clamping cylinder 6 includes a transverse slider 61 slidably connected to the straight ruler plate 5, a fixed cylinder 62 with a lower opening structure and an upper end fixedly connected to the transverse slider 61, and an elastic clamping cylinder 63 installed in the fixed cylinder 62. The elastic clamping cylinder 63 is used to clamp the chalk 8.

[0059] When the chalk 8 is inserted into the clamping cylinder 6, the chalk 8 is inserted into the elastic clamping cylinder 63, and the chalk 8 is clamped by the elastic clamping cylinder 63. During the process of drawing a circle, the lower end of the chalk 8 extends out of the fixed cylinder 62.

[0060] Among them, the upper end of the transverse slider 61 fits and slides in the chute 51 of the straight ruler plate 5, and the lower end extends downward out of the chute 51.

[0061] On the basis of the above embodiment, the elastic clamping cylinder 63 includes a top plate 631 and at least three reed pieces 632 circumferentially distributed on the same circumference. The top plate 631 is installed in the fixed cylinder 62, and the upper ends of the reed pieces 632 are fixedly connected to the edge ends of the top plate 631, and the lower ends are bent inward and extend in an arc-shaped structure.

[0062] Each reed piece 632 can be made of spring steel, stainless steel, and other elastic alloy materials.

[0063] When the chalk 8 is inserted into the elastic clamping cylinder 63, each reed piece 632 squeezes and clamps the chalk 8. During the process of drawing a circle, the upper end of the chalk 8 abuts against the top plate 631.

[0064] In this embodiment: The clamping cylinder 6 further includes a linear driving member 64 installed in the fixed cylinder 62, a placing plate 65 fixedly connected to the driving end of the linear driving member 64 on the upper side, and a pressure sensor 66 installed on the lower side of the placing plate 65. The pressure sensor 66 is communicatively connected to the linear driving member 64, and the elastic clamping cylinder 63 is installed on the lower side of the pressure sensor 66.

[0065] Among them, the linear driving member 64 can be a linear driving mechanism such as a linear motor, an electric cylinder, or a cylinder. And it can be powered by an internal battery. The specific power supply method is a conventional technical means in this field, and no detailed description is made here.

[0066] In the prior art, when using a compass to draw a circle, the distance between the two legs of the compass remains unchanged. The chalk 8 draws a trajectory on a plane to form a circle. During this process, the chalk 8 is consumed and becomes shorter. The distance between the bottom of the chalk 8 and the center of the circle will decrease. Originally, the distance between the two legs of the compass is fixed, but after the chalk 8 becomes shorter, it is equivalent to a change in the structure of the compass. The leg with the chalk 8 will tilt towards the center of the circle, resulting in a smaller radius of the drawn circle.

[0067] For the problems of the above prior art, in this embodiment, during the process of drawing a circle, the straight ruler plate 5 is parallel to the blackboard.

[0068] Before drawing a circle, the chalk 8 abuts against the blackboard. Due to the reaction force of the blackboard, the upper end of the chalk 8 abuts against the top plate 631, and the top plate 631 generates a pressure value on the pressure sensor 66, and this pressure value is the threshold value. During the process of drawing a circle, the upper end of the chalk 8 abuts against the top plate 631, and always applies pressure to the pressure sensor 66 through the top plate 631. When the chalk 8 is consumed, the pressure value measured by the pressure sensor 66 decreases. At this time, the linear drive member 64 is started to continuously drive the placement plate 65 and the elastic cartridge 63 to move forward, pushing the chalk 8 out of the fixed cylinder 62, and the chalk 8 relatively maintains the length extending out of the fixed cylinder 62, so as to ensure that the radius of the drawn circle remains unchanged.

[0069] The clamping cylinder 6 further includes a control switch 68 and a controller (not shown in the figure). The control switch 68 is installed on the base 1 and is communicatively connected to the controller. The controller is used to process the signal of the pressure sensor 66 and control the movement of the linear drive member 64. The controller can automatically adjust the extending length of the chalk 8 according to the feedback signal of the pressure sensor 66 through a preset algorithm to ensure that the pressure of the chalk 8 on the blackboard is consistent.

[0070] Specifically, the control switch 68 has two modes: "automatic" mode and "manual" mode.

[0071] In the "automatic" mode, when the chalk 8 gradually becomes shorter during the process of drawing a circle, the pressure of the chalk 8 on the blackboard will gradually decrease. The pressure sensor 66 monitors the pressure of the chalk 8 on the blackboard in real time and converts the pressure value into an electrical signal and transmits it to the controller. The controller judges the consumption situation of the chalk 8 according to the feedback signal of the pressure sensor 66. If the pressure value is lower than the set threshold value, the controller will drive the linear drive member 64 to make the elastic cartridge 63 extend forward to compensate for the consumed length of the chalk 8. If the pressure value is higher than the set threshold value, the controller will drive the linear drive member 64 to make the elastic cartridge 63 retract backward to keep the pressure consistent.

[0072] In the "manual" mode, the user can manually adjust the extending length of the chalk 8 through the control switch 68 according to the consumption state of the chalk 8.

[0073] Among them, the threshold value can be the pressure value obtained by the pressure sensor 66 when the chalk 8 just abuts tightly against the blackboard. The clamping cylinder 6 further includes a panel (not shown in the figure) installed on the base 1. The panel is communicatively connected to the pressure sensor 66 and the controller to display the pressure value and input the initial pressure value, that is, the threshold value, through the panel.

[0074] On the basis of the above embodiment, a plurality of vertical grooves are vertically formed on the inner wall of the fixed cylinder 62. The edge end of the placement plate 65 is fixedly connected with a vertical block plate, and each vertical block plate is adapted to and vertically slidably connected to each vertical groove to limit the vertical movement of the placement plate 65.

[0075] Please refer to Figure 7 , in this embodiment: The clamping cylinder 6 further includes an elastic clamping sleeve 67 fixedly connected to the inner wall of the open end of the fixed cylinder 62. The elastic clamping sleeve 67 is used to clamp the chalk 8.

[0076] The elastic clamping sleeve 67 can be made of rubber material to clamp the chalk 8 at the open end of the fixed cylinder 62. The clamping part is close to the lower end of the chalk 8, which can reduce the possibility of the chalk 8 breaking during the process of drawing a circle.

[0077] Moreover, the elastic clamping sleeve 67 has an arc-shaped structure to guide the insertion of the chalk 8 and the extension of the elastic cartridge 63 through the arc-shaped surface.

[0078] Please refer to Figures 1-4 , in this embodiment: There are at least two drawing circle mechanisms, and each drawing circle mechanism is circumferentially and uniformly distributed around the central rod 3. In the figure, two drawing circle mechanisms are shown, and the two straight ruler plates 5 are in the same plane.

[0079] During the process of drawing a circle, by installing a plurality of chalks 8 through each drawing circle mechanism at the same time, the plurality of chalks 8 can perform the drawing circle operation simultaneously, improving the drawing circle efficiency and reducing the effect problems of the chalk 8 due to drawing a circle.

[0080] Please refer to Figures 1-3 , in this embodiment: The driving component 4 includes a toothed plate 41 slidably connected to the base rod 2 along the length direction and a gear 42 meshed with the toothed plate 41. The gear 42 is coaxially and fixedly connected to the upper end of the central rod 3.

[0081] When driving the central rod 3 to rotate through the driving component 4, manually pull the toothed plate 41 to drive the gear 42 meshed with the toothed plate 41 to rotate, and the rotation of the central rod 3 can be realized.

[0082] On the basis of the above embodiment, a plurality of support rods 28 are fixedly connected to the extension rod 22 of the base rod 2. An installation groove is formed on the back surface of the toothed plate 41. The installation groove is a stepped groove or a dovetail groove, and the end of the support rod 28 is adapted to and slidably connected to the installation groove to realize the stable support of the toothed plate 41.

[0083] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered by the scope of the claims of the present invention.

Claims

1. A circle-drawing auxiliary device, characterized in that: It includes a base (1), a base rod (2) with one end fixedly connected to the base (1), a central rod (3) perpendicular to the base rod (2) and rotatably connected to the other end of the base rod (2) at the middle, a driving assembly (4) installed on the base rod (2) and with its driving end drivingly connected to the upper end of the central rod (3), and at least one set of circle-drawing mechanisms. The circle-drawing mechanism includes a straight ruler plate (5) parallel to the base rod (2) and with one end fixedly connected to the lower end of the central rod (3), a clamping cylinder (6) slidably connected to the straight ruler plate (5) along the length direction of the straight ruler plate (5), and a second limiting rod (7) threadedly connected to the straight ruler plate (5). The clamping cylinder (6) has a lower opening structure for inserting a piece of chalk (8), and the end of the second limiting rod (7) abuts against the clamping cylinder (6).

2. The circle-drawing assisting device according to claim 1, wherein: The base rod (2) includes a fixed rod (21) with one end fixedly connected to the base (1), an extension rod (22) with one end detachably connected to the other end of the fixed rod (21), and a sliding sleeve (23) slidably connected to the extension rod (22) along the length direction of the extension rod (22). The extension rod (22) is parallel to the fixed rod (21), and the middle end of the central rod (3) is rotatably connected to the sliding sleeve (23). The driving assembly (4) is installed on the extension rod (22).

3. The circle-drawing assisting device according to claim 2, wherein: An applying pressure hole (231) is formed on the upper side of the sliding sleeve (23), and a rotating hole (232) coaxial with it is formed through the bottom of the applying pressure hole (231). The side wall of the central rod (3) abuts against the hole wall of the rotating hole (232), and the central rod (3) is fixedly connected with a central plate (31) rotatably connected in the applying pressure hole (231). The base rod (2) further includes a pressure-applying sleeve (24) and a spring (25) both sleeved on the central rod (3). The pressure-applying sleeve (24) is threadedly connected to the sliding sleeve (23) through the applying pressure hole (231) and abuts against the upper side of the central plate (31). The upper end of the spring (25) abuts against the lower side of the central plate (31), and the lower end abuts against the bottom of the applying pressure hole (231).

4. The circle-drawing assisting device according to claim 3, characterized in that: At least three first balls (311) located on the same circumference are rotatably connected to the upper side of the central plate (31), and a first annular groove (241) coaxial with the central rod (3) is formed on the lower side of the pressure-applying sleeve (24). The spherical surfaces of the first balls (311) all abut against the first annular groove (241).

5. The circle-drawing assisting device according to claim 3, wherein: A second annular groove (233) is coaxially formed at the bottom of the applying pressure hole (231), a third annular groove (234) is coaxially formed at the bottom of the second annular groove (233), at least three second balls (235) evenly distributed in the circumferential direction are rotatably connected to the third annular groove (234), a bottom ring (236) is also rotatably connected to the second annular groove (233), the lower end of the bottom ring (236) simultaneously abuts against the spherical surfaces of the second balls (235), and the lower end of the spring (25) abuts against the bottom ring (236).

6. The circle-drawing auxiliary device according to claim 1, characterized in that: The clamping cylinder (6) includes a transverse slider (61) slidably connected to the straight ruler plate (5), a fixed cylinder (62) with a lower open structure and its upper end fixedly connected to the transverse slider (61), and an elastic clamping cylinder (63) installed in the fixed cylinder (62), and the elastic clamping cylinder (63) is used for clamping the chalk (8).

7. The circle-drawing auxiliary device according to claim 6, wherein: The clamping cylinder (6) further includes a linear driving member (64) installed in the fixed cylinder (62), a placing plate (65) fixedly connected to the driving end of the linear driving member (64) on the upper side, and a pressure sensor (66) installed on the lower side of the placing plate (65), the pressure sensor (66) is communicatively connected to the linear driving member (64), and the elastic clamping cylinder (63) is installed on the lower side of the pressure sensor (66).

8. The circle-drawing assisting device according to claim 6, wherein: The clamping cylinder (6) further includes an elastic clamping sleeve (67) fixedly connected to the inner wall of the open end of the fixed cylinder (62), and the elastic clamping sleeve (67) is used for clamping the chalk (8).

9. The circle-drawing assisting device according to any one of claims 1-8, characterized in that: There are at least two sets of the circle drawing mechanisms, and each of the circle drawing mechanisms is circumferentially and uniformly distributed around the central rod (3).

10. The circle-drawing assisting device according to any one of claims 1-8, characterized in that: The driving assembly (4) includes a toothed plate (41) slidably connected to the base rod (2) along the length direction and a gear (42) meshing with the toothed plate (41), and the gear (42) is coaxially and fixedly connected to the upper end of the central rod (3).

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