A magnetic circle drawing precision instrument

Abstract

The present invention relates to the technical field of teaching tools, and in particular to a magnetic circle drawing accuracy instrument, comprising a center body and a radius ruler; wherein the center body has a plane that can contact a plate body, a cavity for setting a magnetic body is provided on the center body, a circle center positioning mechanism is provided at the center position of the center body, the circle center positioning mechanism is used to set a pen for drawing the center of a circle, a 360-degree angle scale is fixed to the center body, the radius ruler rotates freely around the center line of the center body, and one end of the radius ruler has a connection unit for setting a circle drawing pen for drawing an arc line. The magnetic circle drawing accuracy instrument obtained by the present invention uses magnetism to adsorb it on a blackboard and mark the center position of the circle. The scale on the radius ruler can realize drawing a circle of any precise radius length. The radius ruler can measure and intercept an arc of any angle in combination with the angle scale. It is easy to operate and can quickly draw an accurate and clear circle.

Description

Technical Field

[0001] The invention relates to the technical field of teaching tools, in particular to a magnetic circle drawing precision instrument. Background Art

[0002] The current teaching aid for drawing on the blackboard is usually a compass, the compass body of which is mainly composed of two rods, one of which is equipped with a rubber cone or a small suction cup at the top, and the other rod can be loaded with chalk. The upper ends of the two rods are hinged, and the lower ends can be separated or closed at will to adjust the radius of the drawn arc. In daily teaching use, the existing teaching aid compass has many shortcomings:

[0003] 1. There is no length scale, so the radius of the circle cannot be displayed. If you want to draw a circle with a given radius, you must use a ruler;

[0004] 2. There is no angle scale, so it is impossible to draw, measure, or intercept arcs of any angle;

[0005] 3. The rubber cone of the compass is not fixed firmly to the center of the circle, and it is easy to shift when drawing a circle, especially on a smooth whiteboard. It is often more likely to shift. One hand is often required to hold down the rubber cone to prevent it from shifting, and the other hand is used to rotate the circle. The speed of drawing a circle is slow and it is difficult to operate with one hand. Because the center of the circle is not fixed firmly, it is easy to shift and it is difficult to use force, which often causes the handwriting of the circle to be thin and light, and not clear enough;

[0006] 4. Chalk installation is troublesome, and the length of chalk becomes shorter after use, and it is not easy to adjust the length of chalk;

[0007] The above defects will cause the compass to greatly reduce the teaching quality and efficiency in actual use. In view of the above defects, it is urgently needed to provide a circle drawing instrument that can quickly and accurately draw circles or arcs of any angles to improve the drawing efficiency of the draftsman, thereby improving the teaching quality and efficiency. Summary of the invention

[0008] The purpose of the present invention is to solve the deficiencies of the above-mentioned technology and to provide a magnetic circle drawing accuracy instrument which can draw an arc of any angle on a board and accurately read the radius of the arc or circle.

[0009] In order to achieve the above-mentioned purpose, the present invention is designed to provide a magnetic circle drawing accuracy instrument, which includes a center body and a radius ruler; wherein the center body has a plane that can contact with a plate body, and a cavity is provided on the center body for setting a magnetic body, so that the plane in contact with the plate body can be adsorbed on the plate body by magnetic force when in use; a circle center positioning mechanism is provided at the center position of the center body, and the circle center positioning mechanism is used to set a pen for drawing the center of the circle, and make the center line of the pen coincide with the center line of the center body; the center body is fixed with a 360-degree angle scale, and the scale has a plane, and the corresponding angle is marked on the plane of the scale, The plane of the scale is perpendicular to the center line of the center body and the center point of the angle scale is located on the center line of the center body; the radius ruler is adjustably connected to the center body and the center line of the radius ruler in the length direction intersects perpendicularly with the center line of the center body, the radius ruler rotates freely around the center line of the center body, one end of the radius ruler is provided with a connecting unit for setting a circle drawing pen for drawing arc lines, when in use, the circle drawing pen is directed toward the plate body, and the center line of the pen in the length direction intersects perpendicularly with the center line of the radius ruler in the length direction; the radius ruler is marked with a length scale with the intersection of the center line of the radius ruler and the center line of the circle drawing pen as the starting point 0.

[0010] The central body is provided with a cavity in which a magnetic body is arranged. The cavity is used to place a magnet, and the magnet can make the central body adsorbed on the blackboard.

[0011] The central body is provided with a rotating body which can rotate relative to the center line of the central body. The rotating body is rotationally connected to the central body, and the center line of the rotating body coincides with the center line of the central body.

[0012] The rotating body is provided with a structure for connecting the radius ruler, which is an adjustable connection. On the one hand, the radius ruler can be fixed, and on the other hand, the radius ruler can be moved relative to the center body along its length direction through certain adjustments. The adjustable connection can be achieved by connecting the radius ruler to the rotating body through an adjusting bolt, and the radius ruler can be fixed or pulled by adjusting the tightness of the bolt. In order to better achieve the adjustment function, a compression spring can be provided at the lower end of the adjusting bolt, and a pressure plate can be provided at the lower end of the compression spring. The pressure plate presses on the radius ruler. The pressure acting on the radius ruler can be adjusted by rotating the adjusting bolt. When adjusted to an appropriate position, a moderate fixing pressure can be generated. On the one hand, it can prevent the radius ruler from moving in the beam ruler hole during the circle drawing operation, resulting in a change in the radius length. On the other hand, when the radius length needs to be adjusted, the radius ruler can be pulled to change the radius length with a little force. The adjustable connection can also be provided with a magnetic material at the contact point, and the other is fixed to the magnetic material by mutual attraction. Only when an external force is applied, the two will be displaced; or other connection methods used in life, such as snap-on type. Another form: a guide rail can also be arranged on the radius ruler, the rotating body is slidably connected to the guide rail, and the guide rail is arranged along the length center line of the radius ruler.

[0013] The radius ruler is marked with a length scale with the intersection of the center line of the radius ruler and the center line of the circle drawing pen as the starting point 0, and the radius length is obtained by observing the scale value located at the center line of the center body. A groove or a long hole is provided on the center line of the radius ruler along its length direction. Through the angle of the center body angle scale indicated by the groove or the long hole, the angle of the rotation of the rotating body driven by the radius ruler can be observed, thereby realizing the function of measuring or dividing the arc.

[0014] The center positioning mechanism includes a handle and a pen clip; the handle and the pen clip are fixed as one body, and the handle and the central body are slidably connected. When an external force is applied to the handle toward the plate body, the pen clip moves toward the plate body; the pen clip can fix chalk, and the chalk locates the center of the circle on the plate body; the chalk is located on the center line of the central body. The center positioning mechanism also includes a reset mechanism, and the reset mechanism has the following structure: it includes a tension spring, one end of the tension spring is connected to the pen clip, and the other end of the tension spring is connected to the central body at the handle; under the action of an external force, the pen clip moves toward the plate body under the action of the handle, and the tension spring is stretched at the same time. After the external force disappears, the pen clip is reset under the action of the tension spring. Or the structure of the reset mechanism includes a compression spring, which is arranged in a cavity of a connecting piece. The handle passes through the cavity of the connecting piece. The end of the connecting piece away from the pen clip is fixed to the central body as a whole, and there is a compression plate on the handle in the cavity. The two ends of the compression spring act between the connecting piece near one end of the pen clip and the compression plate. Under the action of external force, the handle compresses the compression spring toward the pen clip. After the external force disappears, the pen clip is reset under the action of the compression spring. The pen clip can be loaded with a circle center positioning chalk or a whiteboard writing refill. When the handle is not pressed, the chalk does not contact the board. If the center position of the circle needs to be located after drawing a circle, the handle can be held, gently pressed and rotated, and the chalk at the lower end will clearly mark the center position of the circle on the blackboard. The handle can pass through the slot or long hole on the radius ruler.

[0015] The connecting unit comprises an outer pen shell, an inner pen shell, an inner spring and an outer spring; the outer pen shell and the inner pen shell are cylindrical, the outer pen shell is sleeved outside the inner pen shell, the center lines of the two coincide, both ends of the inner pen shell are longer than the outer pen shell, and the outer diameter of the inner pen shell is smaller than the inner diameter of the through hole of the outer pen shell; an annular protrusion is arranged on the inner side wall of the lower end of the outer pen shell, and the wall thickness of the lower end part of the outer side wall of the inner pen shell gradually increases from top to bottom, the maximum outer diameter of the outer side wall of the enlarged part of the inner pen shell is larger than the inner diameter of the annular protrusion of the outer pen shell, and the enlarged part of the inner pen shell is at least two forks, wherein the fork refers to the lower end of the inner pen shell along the vertical Several long grooves penetrating the wall thickness are arranged in the direction, so that the end of the inner pen shell is divided into several sheet structures, which are elastic; an outer spring is sleeved on the middle and lower part of the inner pen shell, the lower end of the outer spring abuts against the annular protrusion of the outer pen shell, the upper end of the outer spring is fixed to the middle part of the inner pen shell, a stop convex point is arranged on the outer wall of the inner pen shell above the outer spring, a limiting convex point is arranged on the inner side wall of the top end of the outer pen shell, the limiting convex point is located above the stop convex point, and the inner diameter of the limiting convex point is smaller than the outer diameter of the stop convex point, and the inner pen shell is made of elastic material; an inner spring is arranged at the top end of the inner pen shell, and the inner spring is compressed after the circle drawing pen is installed. The inner spring always applies pressure to the circle drawing pen (chalk), so that the chalk has the force to extend outward. The upper end of the inner pen shell presses it under the action of external force, so that the inner pen shell and the outer pen shell move relative to each other, and the inner pen shell moves toward the plate body. At the same time, the outer spring is stressed, and the lower end of the inner pen shell and the annular protrusion at the lower end of the outer pen shell are displaced. The clamping force on the chalk in the inner pen shell disappears. Under the action of the inner spring, the chalk is further exposed until it touches the plate body, and then the hand is released, and the inner pen shell is reset under the action of the outer spring. The inner side wall of the outer pen shell can also have an annular protrusion to prevent the inner pen clip from falling out. The above designs all solve the problem of the trouble of installing the chalk, and the problem that the length of the chalk cannot be adjusted as the length of the chalk becomes shorter after use. The present design can adjust the length of the chalk by pressing the end of the inner pen shell and extend it to a length suitable for drawing.

[0016] According to the magnetic circle drawing precision instrument described above, it also includes two pieces of chalk, one piece is fixed to the pen clip and used for drawing the center of the circle, and the other piece is installed inside the inner pen shell and used for drawing the circle, namely, the circle drawing pen.

[0017] In order to prevent the radius ruler from falling off when moving, an anti-falling mechanism is fixed on the other end, which can be a nut fixed on the other end, or a block can be fixed.

[0018] The magnetic circle drawing precision instrument replaces the chalk and automatic pen under the circle center locator with a water-based pen for writing on a whiteboard, so that it can be used on a whiteboard, solving the problem that many schools now replace blackboards with whiteboards for health and dust-free considerations, making it difficult to draw circles accurately on whiteboards.

[0019] For the convenience of use and production, the angle scale is preferably a circular ring, with angles engraved on the front of the ring, evenly distributed on it, and marked with corresponding numbers to facilitate reading of the angles. The angle scale has nothing to do with the upper and lower positions of the radius ruler. It is sufficient to ensure that the drawing and reading are not affected. It is best if the upper one is made of transparent material, otherwise it may block the reading of the scale of the lower component.

[0020] The magnetic circle drawing precision instrument obtained by the present invention is loaded with chalk, which is then adsorbed on the blackboard by magnetism during use, and the position of the center of the circle is marked. The scale on the radius ruler can be used to draw a circle with any precise radius length. The radius ruler combined with the angle scale can measure and intercept arcs of any angle. The end of the radius ruler is designed with chalk that can be automatically ejected by pressing. The length is adjustable and the operation is convenient. It can quickly draw an accurate and clear circle. The automatic pen can be replaced with a whiteboard writing pen so that it can be used on a whiteboard. The above-mentioned circle drawing instrument greatly facilitates the drawing work and improves the drawing efficiency of the user. The chalk and automatic pen under the circle center locator can be replaced with a whiteboard writing water-based pen so that it can be used on a whiteboard, solving the problem that many schools now replace blackboards with whiteboards for health and dust-free considerations, and it is difficult to accurately draw circles on whiteboards. In short, it has the following advantages:

[0021] 1. It can be firmly fixed on the blackboard by magnetic adsorption, effectively avoiding the displacement of the center of the circle when drawing a circle. It can be operated with one hand, the operation is simple, the circle drawing speed is fast, and the circle trace is clear.

[0022] 2. Using a radius ruler marked with length scale, the radius length of the circle to be drawn can be accurately adjusted, so that a circle of any radius can be accurately drawn.

[0023] 3. There are angle scales on the angle sheet, which can display the rotation angle of the radius ruler, mark and intercept arcs of any angle, and measure and divide angles.

[0024] 4. The unit for setting the pen can directly load the whole piece of chalk from the bottom. It is easy to install and durable. Pressing the tail of the pen will automatically pop out the chalk. The length of the chalk tip can be freely adjusted, which is easy to use.

[0025] 5. There is a circle center positioning mechanism in the center, which can mark the center position of the circle after drawing it, effectively avoiding the problem that the traditional compass cannot leave a clear mark at the center of the circle, which easily causes the center position to be unclear.

[0026] 6. Implement an operation that can easily and accurately draw a circle on a whiteboard. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a front schematic diagram of the present invention;

[0028] Figure 2It is a side schematic diagram of the present invention;

[0029] Figure 3 It is a schematic diagram of the AA′ section;

[0030] Figure 4 is a schematic cross-sectional view of the connection unit when it is not pressed;

[0031] Figure 5 A schematic diagram of a cross section of a connection unit when it is pressed;

[0032] Figure 6 is a schematic diagram of the centrosome of the present invention;

[0033] Figure 7 A schematic diagram of a circle divided into three equal parts. DETAILED DESCRIPTION

[0034] The present invention will be further described below by way of embodiments in conjunction with the accompanying drawings.

[0035] Embodiment 1:

[0036] like Figure 1-Figure 7 As shown, the present embodiment describes a magnetic circle drawing accuracy instrument, which includes a center body 1 and a radius ruler 2; wherein the center body 1 has a plane that can contact with a plate body, and a cavity 3 in which a magnetic body 10 is arranged on the center body 1, so that the plane in contact with the plate body can be adsorbed on the plate body by magnetic force when in use; a circle center positioning mechanism 4 is arranged at the center position of the center body 1, and the circle center positioning mechanism 4 is used to set a pen for drawing the center of the circle, and make the center line of the pen coincide with the center line of the center body 1; the center body 1 is fixed with a 360-degree angle scale 5, the scale 5 has a plane, and the corresponding angle is marked on the plane of the scale 5, and the scale The plane of 5 is perpendicular to the center line of the center body 1 and the center point with the angle scale is located on the center line of the center body 1; the radius ruler 2 is adjustably connected to the center body 1 and the center line of the radius ruler 2 in the length direction intersects the center line of the center body 1 perpendicularly, the radius ruler 2 rotates freely around the center line of the center body 1, one end of the radius ruler 2 is provided with a connecting unit 8 for setting a circle drawing pen for drawing arc lines, when in use, the circle drawing pen is directed toward the plate body, and the center line of the pen in the length direction intersects the center line of the radius ruler 2 in the length direction perpendicularly; the radius ruler 2 is marked with a length scale with the intersection of the center line of the radius ruler 2 and the center line of the circle drawing pen as the starting point 0.

[0037] The plane where the central body 1 contacts the board body is the base 28 of the central body 1, and the base 28 is screwed and fixed to the central body 1. Above the base 28 is the cavity 3, and the cavity 3 is provided with a magnetic body 10. In order to make the central body 1 more firmly adsorbed on the blackboard, the magnetic body 10 is arranged close to the base 28, and the magnetic body 10 is fixed at the fixed position 29 which is evenly distributed. The magnetic body can be a whole ring, or multiple pieces can be dispersed and fixed on the base 28.

[0038] A rotating body 11 is arranged on the central body 1 and can rotate relative to the center line of the central body 1 . The rotating body 11 is rotationally connected to the central body 1 , and the center line of the rotating body 11 coincides with the center line of the central body 1 .

[0039] A connecting structure is provided between the radius ruler 2 and the rotating body 11. The connecting structure is that two ruler holes for the radius ruler 2 to pass through are symmetrically arranged on both sides of the center of the rotating body 11. The radius ruler 2 passes through the two ruler holes on the rotating body 11, and adjusting bolts 9 are respectively provided on the two ruler holes. A compression spring 18 is provided at the end of the adjusting bolt 9, and a pressure plate 27 is provided at the lower end of the compression spring 18. The pressure plate 27 is pressed on the radius ruler 2. Rotating the adjusting bolt 9 can adjust the pressure acting on the radius ruler 2. Adjusting it to an appropriate position can generate a moderate fixed pressure. On the one hand, it can prevent the radius ruler 2 from moving in the ruler hole during the circle drawing operation to cause the radius length to change. On the other hand, when the radius length needs to be adjusted, the radius ruler 2 can be pulled with a little force to change the radius length.

[0040] A long hole 6 is provided on the center line of the radius ruler 2 along its length direction. Through the angle of the scale plate 5 of the center body 1 indicated by the long hole 6, the angle of rotation of the rotating body 11 driven by the radius ruler 2 can be observed, thereby realizing the function of measuring or dividing the arc.

[0041] The circle center positioning mechanism 4 includes a handle 13 and a pen clip 12; the handle 13 and the pen clip 12 are fixed as one body, and the handle 13 is slidably connected to the central body 1. When an external force is applied to the handle 13 toward the plate body, the pen clip 12 moves toward the plate body; the pen clip 12 can fix a chalk, and the chalk locates the circle center on the plate body; the chalk is located on the center line of the central body 1. The circle center positioning mechanism 4 also includes a reset mechanism, and the reset mechanism includes a compression spring 15, which is arranged in a cavity of a connecting member 14, and the handle 13 passes through the cavity of the connecting member 14, and the end of the connecting member 14 away from the pen clip 12 is fixed as one body with the central body 1, and there is a pressing plate 16 on the handle 13 in the cavity, and the two ends of the compression spring 15 act between the connecting member 14 near the end of the pen clip 12 and the pressing plate 16.

[0042] The connecting unit 8 includes an outer pen shell 19, an inner pen shell 20, an inner spring 24, and an outer spring 21; the outer pen shell 19 and the inner pen shell 20 are cylindrical, the outer pen shell 19 is sleeved outside the inner pen shell 20, the center lines of the two coincide, both ends of the inner pen shell 20 are longer than the outer pen shell 19, and the outer diameter of the inner pen shell 20 is smaller than the inner diameter of the through hole of the outer pen shell 19; an annular protrusion 22 is provided on the inner side wall of the lower end of the outer pen shell 19, and the wall thickness of the lower end part of the outer side wall of the inner pen shell 20 gradually increases from top to bottom, and the maximum outer diameter of the outer side wall of the inner pen shell 20 of the enlarged part 23 is greater than the inner diameter of the annular protrusion 22 of the outer pen shell 19, and the enlarged part of the inner pen shell 20 The inner pen shell 20 has at least two forks 23; an outer spring 21 is sleeved on the middle and lower part of the inner pen shell 20, the lower end of the outer spring 21 is against the annular protrusion 22 of the outer pen shell 19, and the upper end of the outer spring 21 is fixed to the middle part of the inner pen shell 20, and a stop convex point 25 is provided on the outer wall of the inner pen shell 20 above the outer spring 21, and a limit convex point 26 is provided on the inner side wall of the top of the outer pen shell 19, the limit convex point 26 is located above the stop convex point 25, and the inner diameter of the limit convex point 26 is smaller than the outer diameter of the stop convex point 25, and the inner pen shell 20 is made of elastic material; an inner spring 24 is provided at the top of the inner pen shell 20, and the inner spring 24 is compressed after the circle drawing pen is loaded.

[0043] The scale piece 5 is a circular ring, and angles are engraved on the front of the circular ring, evenly distributed on it, and marked with corresponding numbers.

Claims

1. A magnetic circle drawing accuracy instrument, characterized by: It comprises a central body and a radius ruler; wherein the central body has a plane that can contact with a plate body, and a cavity on which a magnetic body is arranged, so that the plane that contacts with the plate body can be adsorbed on the plate body by magnetic force when in use; a circle center positioning mechanism is arranged at the center position of the central body, and the circle center positioning mechanism is used to set a pen for drawing the center of a circle, and make the center line of the pen coincide with the center line of the central body; a 360-degree scale is fixed to the central body, and the scale has a plane, and corresponding angles are marked on the plane of the scale, and the plane of the scale is perpendicular to the center line of the central body and the center point with the angular scale is located on the center line of the central body; the radius ruler is adjustably connected to the central body and the center line of the radius ruler in the length direction is The radius ruler is arranged on the plate body, intersecting perpendicularly with the center line of the central body, and the radius ruler rotates freely around the center line of the central body. One end of the radius ruler has a connection unit for setting a circle drawing pen for drawing an arc line. When in use, the circle drawing pen is directed toward the plate body, and the center line of the pen in the length direction intersects perpendicularly with the center line of the radius ruler in the length direction. The radius ruler is marked with a length scale with the intersection of the center line of the radius ruler and the center line of the circle drawing pen as the starting point 0. A rotating body is arranged on the central body, and the rotating body is rotationally connected to the central body, and the center line of the rotating body coincides with the center line of the central body. The radius ruler is connected to the rotating body, and the center line of the radius ruler in the length direction intersects perpendicularly with the center line of the rotating body. At least one ruler hole for the radius ruler to pass through is arranged on the rotating body. The ruler passes through the ruler hole, and an adjusting bolt is arranged at the upper end of the ruler hole, a compression spring is arranged at the end of the adjusting bolt in the ruler hole, and a pressure plate is arranged at the lower end of the pressure block, and the pressure plate is pressed on the radius ruler; the center positioning mechanism includes a handle and a pen clip; the handle and the pen clip are fixed as a whole, and the handle and the central body are slidably connected. Under the action of an external force applied to the handle toward the plate body, the pen clip moves toward the plate body; the pen clip can fix chalk, and the chalk locates the center of the circle on the plate body; the chalk is located on the center line of the central body; the center positioning mechanism also includes a reset mechanism, and the structure of the reset mechanism is: including a tension spring, one end of the tension spring is connected to the pen clip, and the other end of the tension spring is connected to the central body at the handle; or the structure of the reset mechanism includes a compression spring, and the compression spring is arranged in a cavity of a connecting member, The handle passes through the cavity of the connecting piece, and the end of the connecting piece away from the pen clip is fixed to the central body as a whole, and a pressure plate is provided on the handle in the cavity, and the two ends of the pressure spring act between the connecting piece near one end of the pen clip and the pressure plate; the connecting unit comprises an outer pen shell, an inner pen shell, an inner spring, and an outer spring; the outer pen shell and the inner pen shell are cylindrical, the outer pen shell is sleeved outside the inner pen shell, the center lines of the two coincide, both ends of the inner pen shell are longer than the outer pen shell, and the outer diameter of the inner pen shell is smaller than the inner diameter of the through hole of the outer pen shell; an annular protrusion is provided on the inner side wall at the lower end of the outer pen shell, and the wall thickness of the lower end part of the outer side wall of the inner pen shell gradually increases from top to bottom, the maximum outer diameter of the outer side wall of the enlarged part of the inner pen shell is larger than the inner diameter of the annular protrusion of the outer pen shell, and the enlarged part of the inner pen shell is at least two forks;An outer spring is sleeved in the middle and lower part of the inner pen shell, the lower end of the outer spring abuts against the annular protrusion of the outer pen shell, the upper end of the outer spring is fixed to the middle part of the inner pen shell, a stop convex point is arranged on the outer wall of the inner pen shell above the outer spring, a limit convex point is arranged on the inner side wall of the top end of the outer pen shell, the limit convex point is located above the stop convex point, and the inner diameter of the limit convex point is smaller than the outer diameter of the stop convex point, and the inner pen shell is made of elastic material; an inner spring is arranged at the top end of the inner pen shell, and the inner spring is compressed after the circle drawing pen is installed; the scale piece is a circular ring body, and angles are engraved on the front of the circular ring body, which are evenly distributed on it and marked with corresponding numbers. ;

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