High-precision drawing compass

Abstract

The application relates to the technical field of compasses, in particular to a high-precision drawing compass, which comprises a rule foot, a marking foot, a shell, a grinding disc and a rolling roller; the rule foot is rotationally connected with the marking foot; the shell is installed on the marking foot; a uniform array of trapezoidal grooves is arranged on the side wall surface of the grinding disc; the included angle between the trapezoidal groove and the axis of the grinding disc is 15-30 degrees; a rotating shaft one is fixedly installed in the shell; the grinding disc is fixedly installed on the rotating shaft one and is used for grinding pencil cores; a driving wheel is fixedly installed on the rotating shaft one; the rolling roller is installed in the shell and is used for fixing the pencil core powder ground by the grinding disc on a drawing plane to form a handwriting trace; and the height of the lowest point of the driving wheel is equal to the height of the bottom end of the shell. The application solves the problem that the drawn circle is not accurate due to the change of the length of the marking foot of the compass with the drawing process.

Description

Technical Field

[0001] This invention relates to the field of compass technology, specifically a high-precision drawing compass. Background Technology

[0002] Most existing compasses are herringbone shaped and use pencil lead as the drawing tool. When drawing with such a compass, the pencil lead gradually wears down and shortens as the drawing progresses. Consequently, the length of the drawing leg decreases, resulting in a shorter radius of the circle drawn and ultimately leading to inaccurate circles. Furthermore, this problem worsens as the radius of the circle increases.

[0003] When teaching mechanical design and drafting in universities, students are required to design and draw actual equipment or parts, which involves high-precision fits and therefore requires high drawing accuracy. Mechanical assembly drawings often involve numerous features such as fillets, holes, and shafts that require compasses for drawing. Furthermore, the paper used for assembly drawings is often A3 size, which is relatively large. If the compass's stroke length is shortened, resulting in inaccurate circles, the overall drawing accuracy will be compromised, ultimately leading to inaccurate drawings. Summary of the Invention

[0004] The purpose of this invention is to provide a high-precision drawing compass that solves the problem of inaccurate circles drawn due to changes in the length of the compass's strokes during the drawing process.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A high-precision drawing compass includes compass feet, scribing feet, a housing, a grinding disc, and a roller. The compass feet are rotatably connected to the scribing feet. The housing is rotatably mounted on the scribing feet for loading pencil lead. A rotating shaft is rotatably mounted inside the housing. The grinding disc is fixedly mounted on the rotating shaft for grinding pencil lead. Trapezoidal grooves are evenly arrayed on the side wall of the grinding disc. Each trapezoidal groove is opened along a cylindrical helix on the side wall of the grinding disc. The angle between the tangent of the cylindrical helix and the generatrix of the cylindrical surface of the grinding disc passing through the tangent point is 15-30°. A drive wheel is fixedly mounted on the rotating shaft. A roller is mounted at the lower end inside the housing. The axial length of the roller is equal to the thickness of the grinding disc. The roller is used to fix the pencil lead powder ground by the grinding disc onto the drawing surface to form strokes. The vertical height of the lowest point of the drive wheel and the roller is equal, and this height is equal to the vertical height of the bottom surface of the housing. A pushing device is provided at the top of the housing for pushing the pencil lead to the grinding disc.

[0007] Based on this scheme, the present invention uses a grinding disc to grind the pencil lead housed in the outer casing, thereby grinding the rod-shaped pencil lead into toner. This toner falls downward onto the drawing surface (i.e., the paper surface), and the roller drags across the paper surface during the drawing process. Thus, through the pressure of the roller, the toner is fixed onto the drawing surface, becoming the strokes. In this way, the pencil lead is not used as part of the strokes, thereby avoiding the problem of stroke shortening due to lead consumption.

[0008] It is worth noting that the angle between the trapezoidal groove and the axis of the grinding disc should be selected within the range of 15° to 30°. Specifically, when the angle is less than 15°, the grinding disc will generate greater vibration when grinding the pencil lead, which may cause the pencil lead to break due to frequent alternating stress; when the angle is greater than 30°, the number of trapezoidal grooves grinding the pencil lead at the same time will be too small, resulting in a reduction in the output of toner, which in turn leads to unclear and discontinuous writing.

[0009] It is important to emphasize that in actual design, more detailed consideration should be given to the different types of pen refills used to determine the optimal value of the included angle. For example, for mechanical pen refills, which have a smaller diameter, generally between 0.5 and 1 mm, they are prone to breakage when subjected to vibration. Therefore, a larger angle should be selected between the trapezoidal groove and the axis of the grinding disc to reduce excessive vibration during grinding. On the other hand, for ordinary pencil refills, which have a larger diameter, typically around 2 mm, they are more resistant to vibration. In this case, a smaller angle can be selected between the trapezoidal groove and the axis of the grinding disc to improve grinding efficiency and ensure clear and continuous handwriting.

[0010] In addition, trapezoidal grooves are made on the side wall of the grinding disc to avoid sharp angles at the bottom of the grooves that could easily trap toner, thus facilitating the toner to fall out of the trapezoidal grooves and ensuring the efficiency of toner utilization.

[0011] Preferably, the pushing device includes an annular boss, an end cap, a compression spring, and a push plate; the top of the outer shell has a mounting hole, the annular boss is fixedly installed around the outlet at the top of the mounting hole, the end cap is installed at the top of the outer shell, the inner side wall of the annular boss has an internal thread, and the outer side wall of the lower end of the end cap has an external thread, the end cap and the annular boss are connected by the engagement of the external thread and the internal thread; the bottom end of the end cap has a cylindrical receiving groove, one end of the compression spring is fixedly installed at the bottom end of the receiving groove, and the push plate is fixedly installed at the other end of the compression spring for pushing the pencil lead, and the push plate is disc-shaped, the elastic modulus of the compression spring is 0.05~0.2N / m; a protective unit is provided inside the upper part of the outer shell to share the pressure of the compression spring borne by the pencil lead.

[0012] By designing this technical solution, the pencil lead can be pushed evenly and continuously towards the grinding disc under the action of the compression spring and the push plate as the circular drawing progresses, rather than simply falling onto the grinding disc due to gravity. This ensures that the pencil lead can be stably ground throughout the entire circular drawing process, thereby making the toner output to the paper surface even during the drawing process, which helps to ensure the continuity and clarity of the drawing strokes.

[0013] It should be noted that the elastic modulus of the compression spring should be selected from 0.05 to 0.2 N / m. This is because the pencil leads used in existing compasses are generally 15 to 20 mm in length and 0.5 to 2 mm in diameter. If the elastic modulus of the compression spring is greater than 0.2 N / m, the spring will break the pencil lead within a 15 mm stroke, preventing the invention from properly pushing the pencil lead. Conversely, if the elastic modulus of the compression spring is less than 0.05 N / m, the elastic force accumulated within the limited 15 to 20 mm stroke will be insufficient to ensure the pencil lead is consistently pressed against the grinding disc sidewall with sufficient force throughout the grinding process, thus making it difficult to guarantee stable toner production.

[0014] Preferably, the protection unit includes a support plate, a telescopic sleeve, a drive gear, a transmission gear, a crown gear, a drive cylinder, and a protective ring; the support plate is fixedly installed inside the outer shell, and a through hole is provided on the support plate; the telescopic sleeve is fixedly installed on the top of the support plate, and the telescopic sleeve is coaxial with the through hole; the telescopic sleeve is composed of multiple sleeve units nested sequentially, and each sleeve unit is provided with a limit groove, and adjacent limit grooves cooperate with each other to restrict the telescopic sleeve from rotating about its axis; the drive gear is fixedly installed on a rotating shaft, and the transmission gear... The gear is mounted on the inner wall of the outer casing, and the transmission gear and the drive gear cooperate with each other. The crown gear is sleeved on the telescopic sleeve, and the crown gear and the transmission gear cooperate with each other. The drive cylinder is fixedly mounted on the top of the crown gear, and the drive cylinder cooperates with the receiving groove. The drive cylinder is provided with an internal thread II. The protective ring is fixedly mounted on the outer side of the top of the telescopic sleeve. The push plate abuts against the top of the protective ring. The outer wall of the protective ring is provided with an external thread II that cooperates with the internal thread II. The pitch of the internal thread II and the external thread II are equal, and the pitch is 0.5-4mm.

[0015] This design limits the axial pushing force of the compression spring and pusher plate on the pencil lead, thus preventing the lead from breaking due to prolonged exposure to the large thrust of the compression spring. Specifically, this design uses a protective ring to distribute the thrust of the compression spring on the pencil lead, avoiding the situation where the pencil lead's strength alone is insufficient to resist the spring's thrust. This optimizes the stress conditions on the pencil lead and prevents breakage. Simultaneously, the protective ring, driven by gears and a screw, continuously moves downwards as the drawing progresses, ensuring a continuous supply of lead to the grinding disc and guaranteeing toner output.

[0016] It should be added that the pitch of the internal and external threads should be 0.5–4 mm to ensure smooth engagement under the drive wheel without jamming. Specifically, the selection should be based on factors such as the shape of the threads. If the pitch is less than 0.5 mm, the friction required to engage the threads will be too great, making it difficult for the drive wheel to drive the drive cylinder smoothly. If the pitch is greater than 4 mm, the friction and tightness of the fit between the threads will be insufficient, potentially causing the protective ring to wobble and resulting in unnecessary vibration and damage to the pencil lead.

[0017] Preferably, the drive cylinder includes a fixed part and an elastic part; the outer wall of the fixed part has three U-shaped mounting grooves, the front and rear sides of the U-shapes are respectively connected to the outer and inner side walls of the fixed part, the elastic part is fixedly installed on the lower side wall of the mounting groove, the internal thread is provided on the inner side wall of the elastic part, the top end of the elastic part has a slope, the inclination angle of the slope is ~°, the outer diameter of the fixed part is the same as the diameter of the receiving groove; the return spring is sleeved on the telescopic sleeve, and the upper end of the return spring is fixedly installed on the bottom end of the protective ring, and the other end of the return spring abuts against the top of the crown gear.

[0018] When the original pencil lead is used up and needs to be replaced, the end cap can be removed from the outer casing. At this time, the drive cylinder can be disengaged from the receiving groove, causing the elastic part of the drive cylinder to open outwards so that its internal thread is no longer in the position of the retaining protective ring. Then, under the action of the return spring, the protective ring can pop outwards to achieve reset. Simultaneously, the outward popping of the return spring occurs as the end cap is removed. Therefore, in effect, the compression spring and the return spring are in a resisting state during this process, thus preventing parts from dislodging due to the rapid rebound of the return spring.

[0019] The inclination angle of the inclined plane should be between 45° and 60°. If the inclination angle is less than 45°, the bottom end of the end cap will exert an excessive force along the axis of the drive cylinder on the elastic part during the process of pushing the inclined plane to make the elastic part retract towards the center of the drive cylinder. This may cause plastic deformation of the elastic part, resulting in the elastic part failing to function properly. If the inclination angle is greater than 60°, the vertical space occupied by the inclined plane on the elastic part will be too long. This means that the elastic part will have a large section with a relatively thin thickness, which will affect the strength of the elastic part and make it more susceptible to deformation due to compression.

[0020] Preferably, a second rotating shaft is rotatably installed inside the outer casing, the roller is fixedly installed on the second rotating shaft, the side of the roller abuts against the side of the grinding disc, a driven gear is fixedly installed on the second rotating shaft, and an internal gear that cooperates with the driven gear is fixedly installed on the drive wheel.

[0021] By setting driven gears and internal gears, the drive wheel can drive the rollers to rotate, thus giving the rollers a rolling motion on the paper surface. This rolling motion allows the rollers to better traverse the tiny protrusions on the paper, avoiding the tearing and damage caused by simply dragging the rollers over these protrusions. It should be noted that the rollers have a difference in linear velocity along their axial length, so the dragging of the rollers on the paper surface still occurs. Therefore, the rollers will still drag on the toner, thus still creating ink marks on the drawing surface.

[0022] In addition, due to the specific meshing method of the driven gear and the internal gear, the linear velocity directions of the roller and the grinding disc are opposite at the point of contact. As a result, they slide relative to each other at this point, which generates local vibration. This vibration helps to shake off the toner adhering to the grinding disc and the roller, thereby improving the utilization rate of the toner.

[0023] It should also be noted that the preferred range for the transmission ratio between the internal gear and the driven gear is 3 to 6. When the transmission ratio is greater than 6, the rotational speed of the roller will be too high, causing the toner to be thrown outward by the roller and resulting in splashing. This reduces the amount of toner in the roller's crushing area, affecting the drawing effect. When the transmission ratio is less than 3, the rotational speed of the roller is too slow, so the dragging motion of the roller on the paper surface still dominates. This can lead to the problem of the roller simply dragging the paper on small protrusions, causing the paper to be torn and damaged.

[0024] Preferably, a toner cartridge is fixedly installed inside the outer casing. The toner cartridge has an inlet at the top and an outlet at the bottom. The grinding disc and the roller are both installed inside the toner cartridge. The roller is installed at the outlet. The inlet is aligned with the through hole in the vertical direction. Feed grooves are evenly arrayed on the side wall of the roller.

[0025] Based on this design, the toner can be accurately guided to the rollers by the toner cartridge, and then evenly and continuously fed out by the feed troughs on the rollers. This allows the toner to fall concentrated on the area of ​​the paper surface that is being rolled by the rollers, thereby improving the concentration of the toner and resulting in clearer handwriting on the paper. At the same time, this also avoids the situation where toner scattered on the paper surface affects the cleanliness of the paper.

[0026] Preferably, a stabilizing disc is fixedly installed at both ends of the roller, the outer diameter of the stabilizing disc is equal to the maximum outer diameter of the roller, and the side wall of the stabilizing disc abuts against the side wall of the grinding disc.

[0027] Because the roller has a feeding groove, its overall shape is polygonal. This means the roller's radius changes periodically. This shape causes the scribe lines to vibrate vertically as the roller rotates, resulting in instability during the drawing process and hindering user control and drawing accuracy. Furthermore, this phenomenon causes periodic changes in the scribe line length, leading to unintended results and affecting the accuracy of the final drawing. By using a stabilizing disc, the outline of the roller's contact area with the paper remains circular, thus avoiding these problems.

[0028] Preferably, the lower end of the discharge port is provided with a downward extension, the thickness of the extension and the side wall thickness of the toner cartridge are equal to the width of the feeding groove, and the wall surface of the extension adjacent to the roller is tangent to the movement trajectory of the outermost edge of the roller.

[0029] The extension section functions similarly to a cover, its purpose being to: block the opening of the feed chute that is transferring toner during the rotation of the rollers; and, together with the stabilizing plate blocking both ends of the feed chute, prevent toner from falling out prematurely, thus ensuring that the toner falls concentrated in the area crushed by the rollers; simultaneously, the sum of the thickness of the extension section and the thickness of the toner cartridge's side wall equals the width of the feed chute. This ensures that at any given time, one feed chute will be blocked by the extension section and the toner cartridge, preventing toner from falling downwards, thus creating a relatively enclosed space. This ensures that toner is only fed out with the rotation of the rollers, preventing paper contamination due to toner leakage and contributing to the clarity of the drawn graphics. It is particularly important that the wall surface of the extension section adjacent to the rollers should be tangent to the movement trajectory of the outermost edge of the rollers. This ensures a tight fit between the rollers and the extension section, further preventing toner leakage.

[0030] Based on the above description, the advantages of this invention compared to the prior art are mainly reflected in the following aspects:

[0031] 1. To solve the problem of inaccurate circles drawn due to the changing length of the compass's legs as the drawing progresses, a grinding disc and rollers are incorporated. The grinding disc grinds the pencil lead housed inside the casing, turning the rod-shaped lead into powder. This powder falls onto the drawing surface (the paper), where the rollers compress and drag it to form the lines. This method prevents the pencil lead from being part of the lines, thus avoiding the problem of shortened lines due to lead consumption.

[0032] 2. This invention ensures that the pencil lead continuously presses against the side of the grinding disc to produce ink, thereby guaranteeing the clarity and continuity of the lines drawn by this invention. To this end, a pressure spring and a push plate are incorporated. Under the action of the spring and push plate, the pencil lead is pushed evenly and continuously towards the grinding disc as the circular drawing progresses, rather than simply falling onto the grinding disc due to gravity. This ensures that the pencil lead is stably ground throughout the entire circular drawing process, resulting in an even distribution of ink to the paper during the drawing process, thus contributing to the continuity and clarity of the drawn lines.

[0033] 3. The elastic force from the compression spring on the pencil lead has been optimized to prevent breakage due to excessive pressure. To this end, a protective ring and a drive cylinder have been incorporated. The protective ring distributes the spring's thrust across the pencil lead, avoiding the situation where the pencil lead's strength alone is insufficient to resist the spring's force. This optimizes the stress conditions on the pencil lead and prevents breakage. Furthermore, the protective ring, driven by gears and a screw, continuously moves downwards as the drawing progresses, ensuring a continuous supply of lead to the grinding disc and consistent toner output. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0035] Figure 2 for Figure 1 A schematic diagram of the structure of the drawing part connected to the bottom of the middle stroke;

[0036] Figure 3 for Figure 2 A frontal sectional view;

[0037] Figure 4 for Figure 3 Enlarged view of section A;

[0038] Figure 5 for Figure 2 The diagram shows the structure after removing the outer shell and end caps.

[0039] Figure 6 for Figure 5 The back view;

[0040] Figure 7 for Figure 5 The right view;

[0041] Figure 8 for Figure 7 Enlarged view of section B;

[0042] Figure 9 This is a schematic diagram of the drive cylinder.

[0043] In the diagram: 1. Gauge foot; 2. Scribing foot; 3. Outer shell; 4. End cap; 5. Drive wheel; 31. Internal thread one; 32. Drive cylinder; 33. Protective ring; 34. Return spring; 35. Telescopic sleeve; 36. Support plate; 37. Transmission gear; 41. Compression spring; 42. Push plate; 43. External thread one; 51. Internal gear; 52. Toner cartridge; 53. Grinding disc; 54. Roller; 55. Drive gear; 32 1. Crown gear; 322. Fixing part; 323. Elastic part; 324. Mounting groove; 331. Internal thread two; 332. External thread two; 351. Limiting groove; 521. Feed port; 522. Discharge port; 531. Trapezoidal groove; 532. Rotating shaft one; 541. Stabilizing disc; 542. Feeding groove; 543. Rotating shaft two; 544. Driven gear; 3231. Inclined surface; 5221. Extension part. Detailed Implementation

[0044] The technical solutions of the present invention will now be fully described with reference to the accompanying drawings of the embodiments of the present invention.

[0045] Example 1:

[0046] like Figures 1 to 9 The image shows a first specific embodiment of the present invention.

[0047] Several points need to be explained in advance: First, the pencil lead used as the source of toner in this embodiment is a 0.9mm 2B automatic pencil lead with a length of 15mm, and the included angle between the trapezoidal groove 531 and the axis of the grinding disc 53 is 18°; Second, the compression spring 41 and the return spring 34 are the same type of spring, and their elastic modulus is 0.05N / m; Third, the scribe foot 2 of this invention is rotatably connected to the outer shell 3, and a locking screw is installed at the rotatable hinge point; Fourth, the material of the lower end of the outer shell 3 is made of transparent polypropylene, so that the user can observe the position of the roller 54 through the outer shell 3, thereby accurately grasping the radius of the circle being drawn; Fifth, the height of the lowest point of the drive wheel 5 is equal to the height of the bottom end of the outer shell 3, thereby ensuring that the bottom end of the outer shell 3 can be used as the positioning point during the drawing process, limiting the tilt of the scribe foot 1 and the scribe foot 2, thereby stably achieving high-precision drawing.

[0048] Before drawing the diagram, the end cap 4 is removed from the outer casing 3. At this time, the return spring 34 is in its natural state, the telescopic sleeve 35 is in its extended state, and the three elastic parts 323 of the drive cylinder 32 are all open outwards. Therefore, the inner thread 331 does not engage with the outer thread 332 on the protective ring 33. Afterwards, an automatic pencil lead is inserted into the telescopic sleeve 35, and then the end cap 4 is reinstalled onto the outer casing 3 using a threaded connection. During the process of reinstalling the end cap 4 back onto the outer casing 3, the sidewall of the receiving groove presses against the inclined surfaces 3231 on the three elastic parts 323 of the drive cylinder 32, causing the elastic parts 323 to converge towards the center of the drive cylinder 32 until the inner thread 331 engages with the outer thread 332. At this point, the pencil lead loading is complete.

[0049] When this invention is in operation, firstly, the guide foot 1 and the scribe foot 2 of this invention are opened. Then, the positioning pin on the guide foot 1 is inserted into the paper surface. Next, the locking screw between the outer shell 3 and the scribe foot 2 is loosened, allowing the outer shell 3 to rotate on the scribe foot 2. At this time, the outer shell 3 is placed on the paper surface so that the bottom end of the outer shell 3 is in contact with the paper surface, that is, the plane where the bottom end of the outer shell 3 is located is parallel to the paper surface. Next, the opening angle of the guide foot 1 and the scribe foot 2 is adjusted so that the roller 54 falls at the radius of the circle to be drawn. Then, the locking screw is tightened again to fix the outer shell 3 and the scribe foot 2.

[0050] Subsequently, the invention is rotated on the paper with the positioning pin of the guide foot 1 as the center. As a result, the drive wheel 5 rotates, driving the grinding disc 53 to rotate to grind the automatic pen lead. The automatic pen lead is continuously pressed against the side of the grinding disc 53 under the pushing force of the compression spring 41 and the push plate 42, thereby continuously producing ground toner.

[0051] It should be added that during the process of the pusher plate 42 pushing the automatic ink refill, the pusher plate 42 simultaneously presses against both the ink refill and the protective ring 33. Therefore, the pushing force of the pusher plate 42 acts on both simultaneously. In other words, the protective ring 33 shares some of the pushing force of the pusher plate 42, thus preventing the automatic ink refill from being subjected to excessive pressure and preventing it from breaking. Furthermore, the protective ring 33 gradually moves downwards as the drive wheel 5 rotates, thereby sharing the pressure on the automatic ink refill while ensuring normal toner output. Specifically, the process of the protective ring 33 moving downward is as follows: the drive wheel 5 rotates and drives the drive gear 55 to rotate, which in turn causes the drive cylinder 32 to rotate under the action of the transmission gear 37 and the crown gear 321. At the same time, the limiting groove 351 on the telescopic sleeve 35 prevents it from rotating, so the protective ring 33 cannot rotate. Then, with the help of the engagement of the external thread 2 332 and the internal thread 2 331, the drive cylinder 32 can drive the protective ring 33 to move downward gradually. Thus, the compression spring 41 and the push plate 42 can also gradually push the automatic pen refill to the grinding disc 53 below.

[0052] Furthermore, the drive wheel 5 also drives the internal gear 51 to rotate, which in turn causes the driven gear 544 to rotate the roller 54. This allows the roller 54 to roll on the paper surface, enabling it to better traverse the tiny protrusions and avoid tearing caused by simply dragging the roller over these protrusions. It should be noted that the roller 54 exhibits a difference in linear velocity along its axial length, so the roller 54 still drags on the paper surface. Therefore, the roller 54 continues to drag on the toner, allowing it to still apply toner to the drawing surface to form ink marks.

[0053] Furthermore, due to the specific meshing method of the driven gear 544 and the internal gear 51, the linear velocity directions of the roller 54 and the grinding disc 53 are opposite at the point of contact, so the two slide relative to each other at this point, thereby generating local vibration. This vibration helps to shake off the toner adhering to the grinding disc 53 and the roller 54, thereby improving the utilization rate of the toner.

[0054] As the drawing process continues, the automatic pen refill gradually wears down, the protective ring 33 gradually moves downward, the telescopic sleeve 35 gradually retracts from its extended state, and the return spring 34 is also gradually compressed. Until the telescopic sleeve 35 retracts to its minimum length, the push plate 42 can no longer push the automatic pen refill downward, and the drive wheel 5 can no longer rotate because the protective ring 33 cannot continue to move downward. Therefore, the invention will no longer be able to draw any strokes. The extension 5221 on the toner cartridge 52 also cooperates with the stabilizing disc 541 and the feed chute 542 to prevent residual toner in the toner cartridge 52 from leaking out and contaminating the paper. In short, at this point, the invention will be unable to draw any strokes, and the user will need to replace the pen refill.

[0055] Therefore, the operation of removing the end cap 4 at the beginning of this embodiment is repeated. At this time, as the end cap 4 is removed, the elastic part 323 of the drive cylinder 32 opens outward, causing the mating relationship between the internal thread 331 and the external thread 332 to come into contact. Then, under the elastic force of the return spring 34, the protective ring 33 is pushed outward, and the telescopic sleeve 35 returns to its extended state. The upwardly pushed protective ring 33 receives a buffering reaction force from the compression spring 41, thereby avoiding the problem of part dislocation. Based on the above process, after the end cap 4 is removed from the outer shell 3, the present invention actually restores the initial state of this embodiment. Therefore, automatic pen refills can continue to be loaded into the telescopic sleeve 35. The newly loaded automatic pen refills can continue to push the old automatic pen refills that are not completely consumed downward, thereby realizing the continued reuse of the present invention.

[0056] Example 2:

[0057] Based on Embodiment 1, this embodiment takes the shape of the feeding groove 542 on the roller 54 as a "V" shape, with one side of the "V" shape parallel to the radius of the roller 54. For ease of description, the side of the "V" shape parallel to the radius of the roller 54 is called the straight side, and the other side is called the inclined side.

[0058] In this configuration, when the invention rotates counterclockwise (the invention is based on...), Figure 3 When the viewing angle moves from right to left, the feeding trough 542 uses its "V"-shaped straight edge to scrape out the toner from the toner cartridge 52. At this time, the force exerted on the toner by the straight edge is along the tangential direction of the roller 54. Thus, at the moment when the straight edge is misaligned with the inner wall of the toner cartridge 52, a shearing force perpendicular to the inner wall of the toner cartridge 52 can be applied to the toner, without any component force in other directions. This allows the remaining small particles in the toner to be ground to the maximum extent, forming fine toner particles that are discharged, thereby avoiding the problem of the outlet 522 being blocked due to the long-term accumulation of these small particles. This method of use is more suitable for ordinary pencil leads because the diameter of ordinary pencil leads is usually 2mm. When subjected to grinding, their edges are easily broken into small particles. The particle size of these small particles is generally in the range of 0.4 to 0.7mm, which is much larger than the particle size of the toner obtained from grinding, and may block the outlet 522, affecting the normal drawing of this invention.

[0059] When the invention is rotated clockwise (the invention is...), Figure 3 When the viewing angle moves from left to right, the straight edge of the "V" shape of the feed trough 542 acts as a platform for carrying toner. This platform is parallel to the horizontal plane when it initially receives toner. Since the angle of repose of toner particles is typically between 40 and 50 degrees, this means that the toner can only fall from the straight edge after the roller 54 has rotated 40 to 50 degrees. During this rotation, the vertical height of the toner has decreased by 64% to 77%, allowing the toner to be transported directly to the crushing area of ​​the roller 54. This facilitates concentrated and accurate toner drop, improving toner utilization and ensuring a cleaner paper surface, thus guaranteeing clearer drawings. This method is particularly suitable for automatic pen refills because their diameter is generally 0.5 to 0.9 mm, which is relatively small. The amount of toner ground in a given time is limited, making it crucial to ensure high toner utilization.

[0060] It should be emphasized that, based on the content described above, although the beneficial effects of the present invention have been explained in detail and corresponding specific embodiments have been provided, those skilled in the art can still achieve the same technical effects by making conventional substitutions, modifications, or other alterations to the given technical solutions without creative effort, provided they fully understand the working principle of the present invention. However, such modifications should not be considered as exceeding the scope of the present invention. Specifically, the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A high-precision drawing compass, characterized in that, include: The system comprises a guide foot, a scribing foot, a housing, a grinding disc, and a roller. The guide foot and scribing foot are rotatably connected. The housing is rotatably mounted on the scribing foot for loading pencil lead. A rotating shaft is rotatably mounted inside the housing. The grinding disc is fixedly mounted on the rotating shaft for grinding pencil lead. Trapezoidal grooves are evenly arrayed on the side wall of the grinding disc. Each trapezoidal groove is opened along a cylindrical spiral line on the side wall of the grinding disc. The angle between the tangent of the cylindrical spiral line at a tangent point and the generatrix of the cylindrical surface of the grinding disc passing through that tangent point is 15-30°. A drive wheel is fixedly mounted on the rotating shaft. A roller is mounted at the lower end inside the housing. The axial length of the roller is the same as the thickness of the grinding disc. The roller is used to fix the pencil lead powder ground by the grinding disc onto the drawing surface to form a stroke. The vertical height of the lowest point of the drive wheel and the roller is equal, and this height is equal to the vertical height of the bottom surface of the housing. A pushing device is provided at the top of the housing for pushing the pencil lead to the grinding disc. The pencil lead inside the casing is ground by a grinding disc, so that the stick-shaped pencil lead is ground into powder. This powder falls onto the drawing surface, and the roller drags on the paper during the drawing process. Thus, by the pressure of the roller, the powder is fixed onto the drawing surface and becomes the writing. The pushing device includes an annular boss, an end cap, a compression spring, and a push plate. The top of the outer casing has a mounting hole. The annular boss is fixedly installed around the outlet at the top of the mounting hole. The end cap is installed on the top of the outer casing. An internal thread is formed on the inner sidewall of the annular boss, and an external thread is formed on the outer sidewall of the lower end of the end cap. The end cap and the annular boss are connected by the engagement of the external and internal threads. The bottom of the end cap has a cylindrical receiving groove. One end of the compression spring is fixedly installed at the bottom of the receiving groove, and the push plate is fixedly installed at the other end of the compression spring to push the pencil lead. The push plate is disc-shaped, and the elastic modulus of the compression spring is 0.05–0.2 N / m. A protective unit is provided inside the upper part of the outer casing to share the pressure of the compression spring on the pencil lead. The protection unit includes a support plate, a telescopic sleeve, a drive gear, a transmission gear, a crown gear, a drive cylinder, and a protective ring. The support plate is fixedly installed inside the outer shell and has a through hole. The telescopic sleeve is fixedly installed on the top of the support plate and is coaxial with the through hole. The telescopic sleeve is composed of multiple sleeve units nested sequentially. Each sleeve unit has a limit groove, and adjacent limit grooves cooperate to restrict the telescopic sleeve from rotating around its axis. The drive gear is fixedly installed on a rotating shaft, and the transmission gear rotates... The drive gear is mounted on the inner wall of the outer casing, and the transmission gear and the drive gear cooperate with each other. The crown gear is sleeved on the telescopic sleeve, and the crown gear and the transmission gear cooperate with each other. The drive cylinder is fixedly mounted on the top of the crown gear, and the drive cylinder cooperates with the receiving groove. The drive cylinder is provided with an internal thread II. The protective ring is fixedly mounted on the outer side of the top of the telescopic sleeve. The push plate abuts against the top of the protective ring. The outer wall of the protective ring is provided with an external thread II that cooperates with the internal thread II. The pitch of the internal thread II and the external thread II are equal, and the pitch is 0.5-4mm.

2. The high-precision drawing compass according to claim 1, characterized in that: The drive cylinder includes a fixed part and an elastic part; the outer wall of the fixed part has three U-shaped mounting grooves, the front and rear sides of the U-shapes are connected to the outer and inner side walls of the fixed part respectively, the elastic part is fixedly installed on the lower side wall of the mounting groove, the internal thread is provided on the inner side wall of the elastic part, the top of the elastic part has a bevel, the inclination angle of the bevel is 45-60°, the outer diameter of the fixed part is the same as the diameter of the receiving groove; the high-precision drawing compass also includes a return spring, the return spring is sleeved on the telescopic sleeve, and the upper end of the return spring is fixedly installed on the bottom end of the protective ring, the other end of the return spring abuts against the top of the crown gear.

3. A high-precision drawing compass according to claim 1, characterized in that: A second rotating shaft is rotatably installed inside the outer casing. The roller is fixedly installed on the second rotating shaft. The side of the roller abuts against the side of the grinding disc. A driven gear is fixedly installed on the second rotating shaft. An internal gear that cooperates with the driven gear is fixedly installed on the drive wheel. The transmission ratio between the internal gear and the driven gear is 3 to 6.

4. A high-precision drawing compass according to claim 3, characterized in that: A toner cartridge is fixedly installed inside the outer casing. The toner cartridge has an inlet at the top and an outlet at the bottom. The grinding disc and the roller are both installed inside the toner cartridge. The roller is installed at the outlet. The inlet is aligned with the through hole in the vertical direction. Feeding grooves are evenly arrayed on the side wall of the roller. The feeding grooves are V-shaped grooves, and one side of the "V" is parallel to the radius of the roller.

5. A high-precision drawing compass according to claim 3, characterized in that: Stabilizing discs are fixedly installed at both ends of the roller. The outer diameter of the stabilizing disc is equal to the maximum outer diameter of the roller, and the sidewall of the stabilizing disc abuts against the sidewall of the grinding disc.

6. A high-precision drawing compass according to claim 4, characterized in that: The lower end of the discharge port is provided with a downward extension. The sum of the thickness of the extension and the thickness of the side wall of the toner cartridge is equal to the width of the feeding groove. The wall of the extension adjacent to the roller is tangent to the movement trajectory of the outermost edge of the roller.

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