阅读说明：本技术 一种自带刻度的圆规 (Compasses with scales ) 是由 韩景 黄永泉 于 2020-06-22 设计创作，主要内容包括：本发明涉及一种自带刻度的圆规,包括圆规头,圆规头上可转动地设有针脚和铅脚,所述针脚底部设有一圆规针,所述铅脚底部设有一铅芯；所述圆规头上设有一安装口,所述安装口内可水平旋转地设有刻度件,所述刻度件上标有刻度,所述刻度件螺纹连接一定位机构,所述定位机构包括螺纹连接于刻度件的螺杆、连接于螺杆底部的定位板,所述定位机构可做升降运动。本发明涉及圆规领域,刻度件随着针脚和铅脚的拉动而转动,刻度件可显示圆规针和铅芯的距离,采用螺杆螺纹传动的结构,针脚和铅脚不容易移动,解决了圆规依赖量具测量半径进行画圆,画圆效率慢,携带量具不便,以及因量具误差造成画圆不准确的技术问题。(The invention relates to a pair of compasses with scales, which comprises a compass head, wherein a stitch and a lead foot are rotatably arranged on the compass head, a compass needle is arranged at the bottom of the stitch, and a lead core is arranged at the bottom of the lead foot; the head of the compass is provided with a mounting opening, a scale piece can be arranged in the mounting opening in a horizontal rotating manner, scales are marked on the scale piece, the scale piece is in threaded connection with a positioning mechanism, the positioning mechanism comprises a screw rod connected with the scale piece in a threaded manner, and a positioning plate connected to the bottom of the screw rod, and the positioning mechanism can be in lifting motion. The invention relates to the field of compasses, wherein a scale part rotates along with the pulling of a pin and a lead pin, the scale part can display the distance between a compass needle and a lead core, and the pin and the lead pin are not easy to move due to the adoption of a screw thread transmission structure, so that the technical problems that the compasses rely on a measuring tool to measure the radius to draw circles, the circle drawing efficiency is low, the measuring tool is inconvenient to carry, and the circle drawing is inaccurate due to the error of the measuring tool are solved.)

1. The utility model provides a from compasses of taking scale, includes the compasses head, the overhead rotatory stitch and the plumbous foot of being equipped with of compasses, the stitch bottom is equipped with a compasses needle, plumbous sole portion is equipped with a lead, its characterized in that: the top of the pin is provided with a first connecting part, the first connecting part is provided with a first positioning hole, the top of the lead pin is provided with a second connecting part, the second connecting part is provided with a second positioning hole, and the first connecting part and the second connecting part are respectively provided with a convex point; the compass head is provided with a mounting hole, the mounting hole is internally provided with a scale piece in a horizontal rotation manner, the scale piece is marked with scales, the compass head is provided with an indication mark pointing to the scales, the scale piece is in threaded connection with a positioning mechanism, the positioning mechanism comprises a screw rod in threaded connection with the scale piece and a positioning plate connected to the bottom of the screw rod, the positioning mechanism can do lifting motion, the middle part of the positioning plate is provided with a vertically arranged long hole, the positioning plate is symmetrically provided with small holes at two sides of the long hole, two bumps are respectively inserted into the two small holes, the two bumps are respectively inserted into the two small holes in a rotatable and transversely movable manner, the first connecting part is rotatably abutted against one surface of the positioning plate, the second connecting part is rotatably abutted against the other surface of the positioning plate, the compass head is provided with a fixing piece and at least one fixing hole, the fixing piece penetrates through the first positioning hole, the long hole, the second positioning hole and the fixing hole.

2. The compasses with scales of claim 1, wherein: the scale part comprises a nut in threaded connection with the screw rod and a scale ring which is rotatably sleeved on the outer side wall of the thread.

3. The compasses with scales of claim 2, wherein: the inner side wall of the scale ring is provided with at least one rib, and the outer side wall of the nut is provided with a plurality of anti-slip strips matched with the rib.

4. The compasses with scales of claim 2, wherein: the nut top surface is the bellied cambered surface structure that makes progress, the nut bottom is the bellied cambered surface structure that makes progress, installing port bottom and top are equipped with the arc groove that corresponds with the nut.

5. The compasses with scales of claim 1, wherein: the small hole is a long round hole.

6. The compasses with scales of claim 1, wherein: the inside mounting hole that is located of the compasses head is equipped with a cavity that open side down, be equipped with the opening that switches on in cavity and mounting hole in the compasses head, the locating plate is located the opening below, the screw rod run through the opening connect in the scale piece, the fixed orifices switches on in the cavity.

7. The compasses with scales of claim 1, wherein: the compasses top of head portion is equipped with a handheld portion, be equipped with the lift groove in the handheld portion perpendicularly, the lift groove switches on in the installing port, the screw rod extends to in the lift groove.

8. The compasses with scales of claim 1, wherein: the compasses are characterized in that a locking cover is arranged at the position, located at the mounting port, of the compasses head, at least two clamping points are arranged on the locking cover, clamping grooves corresponding to the clamping points are formed in the compasses head, and the clamping points are detachably inserted into the clamping grooves.

9. The compasses with scales of claim 1, wherein: the fixing piece is a screw which is fixed on the head of the compass through a nut.

10. The compasses of any of claims 1 to 9, wherein: an automatic core-discharging mechanism is detachably arranged on the lead foot, and the lead core is arranged on the automatic core-discharging mechanism.

Technical Field

The invention relates to the field of compasses, in particular to a pair of compasses with scales.

Background

The compasses are used for drawing circles or arcs, are usually used for drawing by a ruler, usually comprise a compasses head, and a stitch and a lead foot which are rotatably arranged on the compasses head, when the compasses draw circles, the stitch and the lead foot are pulled away by hands, the length of the stitch and the lead foot is the radius of the circle by measuring through a caliper, the compasses draw the circles on paper, the distances between the stitch and the lead foot are measured on the compasses, the stitch and the lead foot are in an inclined state, errors are easy to occur, the circle is not accurately drawn, some rulers have inaccurate printing conditions, errors exist in measurement, accurate circles are difficult to draw, the measured stitch and lead foot are likely to deviate, the situation that a circle drawn in the drawing process has different radiuses, namely the drawn circle is not enough, when a small circle is drawn, the distances between the stitch and the lead foot are difficult to achieve accuracy, and the distance between the stitch and the lead foot is likely to change under stress, the circle drawn by the method is inaccurate, and the circle is drawn by the method, so that measuring steps are increased, and the circle drawing efficiency is low. Some compasses are provided with scales, the distance between the pin and the lead pin can be positioned through the scales, however, the compasses with the scales are not accurate.

Chinese patent application No.: 201821370508.0, a compass is disclosed, which comprises a compass handle, a compass neck, a positioning foot, a drawing foot, the compass handle is connected on the compass neck, the upper part of the positioning foot and the upper part of the drawing foot are connected by a pivot, and the rotating shaft extends along the horizontal direction, the lower end of the positioning foot is a compass tip, the lower end of the drawing foot is a painting brush, the compass neck is fixedly arranged at the top end of the drawing foot, the upper end part of the compass neck is a ball head, the lower part of the compass handle is provided with a spherical inner cavity matched with the ball head, the ball head can be embedded in the spherical inner cavity in a universal rotation way, the compass handle can rotate in a universal way relative to the compass neck, when in use, a finger only needs to hold the compass handle, through continuous twisting of the wrist, the compass can complete a circle drawing once, compared. When the compasses draw circles, the distance between the compass point and the painting brush needs to be positioned by the ruler, the measuring tool is inconvenient to carry, the circle drawing speed is slow, the situation that the distance between the compass point and the painting brush is inaccurate can exist, and the circle drawing efficiency is low.

Chinese patent application No.: 201820773204.2, discloses a compasses with scale, including the pivot that has the needle point, the calibrated scale that has the nib, the middle part of needle point and the middle part of calibrated scale pass through the hinge and articulate together, the calibrated scale is the shape of falling L, the upper portion of calibrated scale is provided with the scale, the position that the pivot corresponds the scale is provided with transparent reading area, is provided with coupling mechanism between the calibrated scale that the upper portion of pivot and scale place. The compasses can directly draw a circle with a designated radius by measuring a required radius value on the compasses through the arranged dial with scales. However, when the compasses draw circles, the rotating shaft is in an inclined state, the rotating shaft is held by a hand to rotate and is not easy to rotate, and in addition, the rotating shaft and the scales are easy to rotate during rotation, so that the condition of inaccurate circle drawing is easily caused.

Chinese patent application No.: 201620095082.7, a compasses with scale is provided, including compasses handle, compasses shell, first compasses stabilizer blade, second compasses stabilizer blade, compasses point and pencil, the compasses handle is connected in the center of compasses shell roof, and the compasses shell is all connected to the upper end of first compasses stabilizer blade, the upper end of second compasses stabilizer blade, and the lower extreme of first compasses stabilizer blade is connected to the compasses point, and the lower extreme of second compasses stabilizer blade is connected to the pencil, still include first bevel gear, second bevel gear, first gear, second gear, third gear, fourth gear, first gear shaft, second gear shaft, third gear shaft, fourth gear shaft and fifth gear shaft in the compasses shell. The compasses are provided with the first bevel gear, the second bevel gear, the first gear, the second gear, the third gear and the fourth gear, the mutual matching structure of the five gears is complex, the production and installation are not easy, the production cost is high, the gears are more, the transmission error among the gears is larger, and the actual circle drawing precision is not high.

Disclosure of Invention

Therefore, in order to solve the problems, the invention provides a pair of compasses with scales. The compasses solve the technical problems that the compasses draw circles depending on the radius measured by the measuring tool, the circle drawing efficiency is low, the measuring tool is inconvenient to carry, and the circles are not accurately drawn due to the error of the measuring tool.

In order to achieve the purpose, the invention adopts the following technical scheme:

a compass with scales comprises a compass head, wherein a stitch and a lead foot are rotatably arranged on the compass head, a compass needle is arranged at the bottom of the stitch, a lead core is arranged at the bottom of the lead foot, a first connecting part is arranged at the top of the stitch, a first positioning hole is formed in the first connecting part, a second connecting part is arranged at the top of the lead foot, a second positioning hole is formed in the second connecting part, and salient points are respectively arranged on the first connecting part and the second connecting part; the compass head is provided with a mounting hole, a scale piece is arranged in the mounting hole in a horizontal rotating manner, scales are marked on the scale piece, an indication mark pointing to the scales is arranged on the compass head, the scale piece is in threaded connection with a positioning mechanism, the positioning mechanism comprises a screw rod in threaded connection with the scale piece and a positioning plate connected to the bottom of the screw rod, the positioning mechanism can do lifting motion, a vertically arranged long hole is arranged in the middle of the positioning plate, small holes are oppositely arranged on two sides of the long hole on the positioning plate, two bumps are respectively inserted into the two small holes, the two bumps are respectively inserted into the two small holes in a rotatable and transversely movable manner, the first connecting part is rotatably abutted against one surface of the positioning plate, the second connecting part is rotatably abutted against the other surface of the positioning plate, and a fixing part and at least one fixing hole are arranged on the compass head, the fixing piece penetrates through the first positioning hole, the long hole, the second positioning hole and the fixing hole.

Further:

the scale part comprises a nut in threaded connection with the screw rod and a scale ring which is rotatably sleeved on the outer side wall of the thread.

The inner side wall of the scale ring is provided with at least one rib, and the outer side wall of the nut is provided with a plurality of anti-slip strips matched with the rib.

The nut top surface is the bellied cambered surface structure that makes progress, the nut bottom is the bellied cambered surface structure that makes progress, installing port bottom and top are equipped with the arc groove that corresponds with the nut.

The small hole is a long round hole.

The inside mounting hole that is located of the compasses head is equipped with a cavity that open side down, be equipped with the opening that switches on in cavity and mounting hole in the compasses head, the locating plate is located the opening below, the screw rod run through the opening connect in the scale piece, the fixed orifices switches on in the cavity.

The compasses top of head portion is equipped with a handheld portion, be equipped with the lift groove in the handheld portion perpendicularly, the lift groove switches on in the installing port, the screw rod extends to in the lift groove.

The compasses are characterized in that a locking cover is arranged at the position, located at the mounting port, of the compasses head, at least two clamping points are arranged on the locking cover, clamping grooves corresponding to the clamping points are formed in the compasses head, and the clamping points are detachably inserted into the clamping grooves.

The fixing piece is a screw which is fixed on the head of the compass through a nut.

An automatic core-discharging mechanism is detachably arranged on the lead foot, and the lead core is arranged on the automatic core-discharging mechanism.

By adopting the technical scheme, the invention has the beneficial effects that:

according to the compasses, the scale part is arranged on the compasses, when the compasses are used, the stitch and the lead foot are pulled, the first connecting part and the second connecting part respectively rotate by taking the first positioning hole (or the second positioning hole) as a circle center, the convex point on the first connecting part rotates and transversely moves along the small hole, the convex point on the second connecting part rotates and transversely moves along the small hole, the two convex points oppositely move, the positioning mechanism is respectively jacked upwards in the rotating process of the two convex points, the positioning mechanism moves upwards, the positioning mechanism is connected to the scale part in a threaded manner, the screw rod moves upwards and simultaneously drives the scale part to rotate, and the numerical value on the scale part is the numerical value of the distance between the compass needle and the lead core; the locating piece is arranged on the long hole on the locating mechanism in a penetrating way, the long hole can move up and down relative to the locating piece, the long hole has a limiting effect, meanwhile, the two convex points can rotate respectively and can move transversely in the two small holes, the convex points also have a limiting effect, when the numerical value of the scale ring is zero, the two feet of the compass are in a closed state, the locating piece is propped against the upper end of the long hole, the two convex points are propped against one end of the small hole close to the long hole respectively, when the two feet of the compass are opened, the locating piece moves upwards relative to the head of the compass, the locating piece drives the two feet to move upwards, meanwhile, the small hole rotates and transversely moves along the direction far away from the long hole, when the numerical value of the scale ring is the maximum value, the two feet of the compass open the maximum angle, the locating piece, the salient points and the positioning parts can be protected, and the salient points and the positioning parts are prevented from being deformed or worn due to excessive stress; in the lifting process of the positioning mechanism, the circle center of the fixing hole (or the circle center of the first positioning hole or the circle center of the second positioning hole) and the connection point of the circle centers of the two convex points form a stable structure of an isosceles triangle all the time, so that the positioning mechanism is stable in vertical lifting, the symmetrical movement of the stitch and the lead foot can be realized, the distance between the compass needle and the lead core is consistent with the numerical value of the scale ring, the error of circle drawing is small, and in the process of circle drawing and rotation of the compass, the angle between the stitch and the lead foot cannot be changed, so that a relatively accurate circle can be drawn; only the mode that the screw rod drives the scale piece to rotate is adopted, namely a transmission mode, the structure is simple, the mode of screw rod transmission is adopted, the accuracy is high, in the process of circle drawing and rotation of the compasses, the angle between the pin and the lead pin cannot be changed, and a relatively accurate circle can be drawn; the first connecting part can be rotatably abutted against one surface of the positioning plate, the second connecting part can be rotatably abutted against the other surface of the positioning plate, and the structure ensures that the pins and the lead pins are not easy to deviate when rotating; furthermore, if the scale of the scale part can not be adjusted to zero after being assembled, when the compasses are assembled, the screw rod is in threaded connection with the scale part, the positioning mechanism is lifted to the position that the first positioning hole, the second positioning hole and the fixing hole are overlapped, the fixing part needs to be inserted into the first positioning hole, the second positioning hole and the fixing hole for fixing, at the moment, the indication mark points to the numerical value 0 of the scale part, the assembly difficulty of the method is higher, after the assembly is finished, the indication mark can be drawn or pasted on the head of the compasses, the indication mark pointing to 0 of the assembly method is difficult to be arranged at the center line of the compasses, the reading of a user is inconvenient, errors are easy to generate, the attractiveness of the compasses is influenced, the allocation method has the possibility that the angle deviation of the scale part is larger, the scale part can not be seen by people from the mounting hole, at the moment, the assembly needs to be reassembled, and the assembly is inconvenient, the scale part comprises, The scale ring can be rotatably sleeved on the outer side wall of the thread, the stitch and the lead foot can be kept in a closed state after the compasses are assembled, the scale ring and the nut can relatively rotate by rotating the scale ring, so that 0 scale of the scale ring is aligned with the indication mark, and the scale ring can be manually reset to zero; furthermore, the friction force between the scale ring and the nut is increased due to the matching of the ribs and the anti-slip strips, so that the scale ring and the nut are not easy to move relatively, and the accuracy of measurement is ensured; the top surface of the nut is of an upward-convex cambered surface structure, the bottom of the nut is of a downward-convex cambered surface structure, and when the nut rotates, friction between the nut and the cambered groove can be reduced; furthermore, the small hole is a long round hole, so that the convex point can transversely move in the small hole, the convex point transversely moves horizontally relative to the small hole, and the measurement error is reduced; furthermore, the screw rod can be lifted in the lifting groove and the through hole, the inner walls of the lifting groove and the through hole not only have a guiding function, but also have a horizontal supporting function on the screw rod, so that the acting force between the nut and the screw rod can be reduced, the abrasion between the nut and the screw rod can be reduced, and the screw rod can be prevented from being deformed; furthermore, the lock cover of the compass head can be fixed through the clamping point and the clamping groove, the whole structure of the compass is simple, the compass head is composed of the compass head, the pin, the lead foot, the scale part and the positioning mechanism, the assembly and disassembly are easy, when a certain part is damaged, the assembly and disassembly can be carried out, and the production cost is low; furthermore, detachably is equipped with an automatic mechanism of loosing core on the lead foot, but the length of the automatically regulated plumule of the mechanism of loosing core, do not need the length of artifical manual regulation plumule, improved the efficiency of drawing the circle, and the automatic mechanism of loosing core prevents that plumule overlength or plumule from being short excessively to lead to the actual distance of plumule lower extreme and compasses needle lower extreme and the distance on the scale spare to produce certain error, and the setting of the automatic mechanism of loosing core makes the compasses can draw more accurate circle.

Drawings

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

FIG. 2 is a cross-sectional view of FIG. 1;

FIG. 3 is a rear view of FIG. 1;

FIG. 4 is a schematic view of the opened state of the compasses;

FIG. 5 is a cross-sectional structural view of FIG. 4;

FIG. 6 is a schematic view of the exploded state structure of the present invention;

FIG. 7 is a schematic view of another exploded view of the present invention;

FIG. 8 is a top plan view of the scale member in an enlarged exploded state from above;

FIG. 9 is a schematic structural view of an automatic core-ejecting mechanism arranged on the compasses;

FIG. 10 is an exploded view of the compass and the automatic core ejection mechanism.

Detailed Description

The invention will now be further described with reference to the accompanying drawings and detailed description.

Referring to fig. 1 to 8, the compasses provided with scales in this embodiment include a compass head 1, a stitch 2 and a lead pin 3 are rotatably disposed on the compass head 1, a compass needle 20 is disposed at the bottom of the stitch 2, a lead core 30 is disposed at the bottom of the lead pin 3, a first connecting portion 21 is disposed at the top of the stitch 2, a first positioning hole 211 is disposed on the first connecting portion 21, a second connecting portion 31 is disposed at the top of the lead pin 3, a second positioning hole 311 is disposed on the second connecting portion 31, and salient points 4 are respectively disposed on the first connecting portion 21 and the second connecting portion 31; the compasses head 1 is provided with a mounting port 11, a cavity 12 with a downward opening is arranged below the mounting port 11 in the compasses head 1, and a through port 13 communicated with the cavity 12 and the mounting port 11 is arranged in the compasses head 1; a locking cover 10 is arranged on the position, located at the mounting port 11, of the compass head 1, at least two clamping points 101 are arranged on the locking cover 10, clamping grooves 102 corresponding to the clamping points 101 are formed in the compass head 1, the clamping points 101 are detachably inserted into the clamping grooves 102, viewing ports 100 are respectively and oppositely arranged on the locking cover 10 and the compass head 1, and the viewing ports 100 are communicated with the mounting port 11; the scale piece 5 is horizontally and rotatably arranged in the mounting hole 11, the scale piece 5 comprises a nut 51 and a scale ring 52 which is rotatably sleeved on the outer side wall of the thread, scales are marked on the scale ring 52, an indication mark 14 pointing to the scales is arranged on the head 1 of the compass, three ribs 521 are arranged on the inner side wall of the scale ring 52, a positive integer of anti-slip strips 511 matched with the ribs 521 are arranged on the outer side wall of the nut 51, the top surface of the nut 51 is of an upward convex arc surface structure, the bottom of the nut 51 is of a downward convex arc surface structure, and arc grooves 111 corresponding to the nut 51 are arranged at the bottom and the top of the mounting hole 11; the scale part 5 is in threaded connection with a positioning mechanism 6, the positioning mechanism 6 comprises a screw rod 61 in threaded connection with the nut 51 and a positioning plate 62 connected to the bottom of the screw rod 61, the positioning plate 62 is positioned below the through hole 13, the screw rod 61 penetrates through the through hole 13 to be connected to the scale part 5, the top of the compass head 1 is provided with a handheld part 15, a lifting groove 151 is vertically arranged in the handheld part 15, the lifting groove 151 is communicated with the mounting hole 11, and the screw rod 61 extends into the lifting groove 151; locating plate 62 middle part is equipped with the slot hole 621 of vertical setting, it is equipped with aperture 622 to lie in slot hole 621 both sides opposition on locating plate 62, two bumps 4 are inserted respectively and are located two apertures 622, but two bumps 4 are rotatable and lateral shifting's the inserting of lateral shifting respectively and locate two apertures 622, aperture 622 is the slotted hole, the rotatable one of them face of leaning on in locating plate 62 of first connecting portion 21, the rotatable another side of leaning on in locating plate 62 of second connecting portion 31, be equipped with mounting 16 and two fixed orificess 17 on the compasses head 1, fixed orifices 17 switches on in cavity 12, mounting 16 passes first locating hole 211, the slot hole 621, second locating hole 311 and fixed orifices 17, mounting 16 is the screw, the screw passes through nut 161 and is fixed in compasses head 1.

The small hole 622 is an oblong hole which is of a known structure, and the two salient points 4 can move left and right relative to the oblong hole, which is not described in detail herein.

The fixing element 16 may also be a screw or other component, and the fixing element 16 fixes the first positioning hole 211, the second positioning hole 311 and the fixing hole 17, which are known components and will not be described herein again.

The scale member 5 can be directly provided with scales on the nut 51 without the scale ring 52, and the structure is difficult to return to zero and position the scale ring 52 when the compasses are installed and is set according to the situation.

The threads on the screw 61 are trapezoidal threads, so that the screw has the characteristics of good strength, good alignment, adjustable clearance, good process performance and the like, is a known structure, and is not described in detail herein.

The engagement between the card slot 102 and the card point 101 is fixed by a known technique, and will not be described herein.

The vertical dimension of the small hole 622 is slightly larger than the diameter of the salient point 4, and usually ranges from 0.1mm to 0.2mm, and is set according to the situation; the dimension of the long hole 621 in the transverse direction is slightly larger than that of the fixing member 16 in the transverse direction, and generally ranges from 0.1mm to 0.2mm, and is set according to the situation; the lifting groove 151 is cylindrical, and the radius of the lifting groove 151 is slightly larger than the radius of the screw 61, generally ranging from 0.1mm to 0.2mm, and is set according to the situation.

The above-mentioned snap-fit of the snap-in point 101 and the snap-in groove 102 is a known technical means, and the detachable connection can be realized by utilizing the micro-elasticity of plastics, which is not described herein again.

When the numerical value of the compass graduated ring 52 is zero, two feet of the compass are in a closed state, the positioning piece 16 abuts against the upper end of the long hole 621, and the two salient points 4 respectively abut against one end of the small hole 622 close to the long hole; when the numerical value of the scale ring is the maximum value, the two feet of the compass are in the maximum opening angle, the positioning piece 16 abuts against the lower end of the long hole 621, and the two salient points 4 respectively abut against one end of the small hole 622 far away from the long hole 621; in the process that the two legs of the compasses are opened to the maximum distance from the closed state, the graduated ring 52 rotates for a circle; the compasses can be arranged according to the conditions without adopting the mode.

The use mode of the invention is as follows:

when the compasses are installed, the parts of the compasses head 1, the pin 2, the lead pin 3, the scale part 5 and the positioning mechanism 6 need to be installed and combined, the lock cover 10 on the compasses head 1 is in a detachable state, the scale part 5 is placed in the installation opening 11, and then the clamping point 101 on the lock cover 10 is inserted into the clamping groove 102 on the compasses head 1 for fixing; the salient point 4 of the first connecting part 21 is inserted into one of the small holes 622 on the positioning plate 62, the salient point 4 of the second connecting part 31 is inserted into the other small hole 622 on the positioning plate 62, the first connecting part 21 abuts against one surface of the positioning plate 62, the second connecting part 31 abuts against the other surface of the positioning plate 62, the pin 2 and the lead pin 3 are in a closed state, the positioning mechanism 6 is inserted into the cavity 12 from the lower part of the compass head 1, the thread on the positioning mechanism 6 is inserted into the screw hole of the nut 51 until the first positioning hole 211, the second positioning hole 311 and the two fixing holes 17 are overlapped, at this time, the pin 2 and the lead pin 3 are in a closed state, the screw is inserted into the first positioning hole 211, the long hole 621, the second positioning hole 311 and the two fixing holes 17, the nut 161 is locked and fixed, the pin 2 and the lead pin 3 are kept closed, and the scale ring 52 is rotated by hand, so that the scale ring 52 and the, aligning the 0 scale of the scale ring 52 with the indication mark 14 and manually zeroing; in the whole assembling process, the pin 2 and the lead pin 3 are kept closed, and the pin 2 and the lead pin 3 can be fixed by hands; in this way, the installation and the disassembly are simple, the maintenance and the replacement are easy, the graduated ring 52 can be adjusted and calibrated manually, and the scales of the graduated ring 52 and the indication marks 14 are easy to be positioned by naked eyes and are not easy to deviate, so that the drawn circle is accurate; during the use, the stitch 2 and the lead foot 3 are pulled by hands, the stitch 2 and the lead foot 3 respectively rotate by taking the first positioning hole 211 (or the second positioning hole 311) as a circle center, the stitch 2 and the lead foot 3 do opposite motions, the salient point 4 on the first connecting part 21 rotates and transversely moves along the small hole 622, the salient point 4 on the second connecting part 31 rotates and transversely moves along the small hole 622, the two salient points 4 oppositely move, the positioning mechanism 6 is respectively jacked upwards in the rotating process of the two salient points 4, the positioning mechanism 6 upwards moves, the positioning mechanism 6 is in threaded connection with the scale part 5, the screw rod 61 upwards moves and simultaneously drives the scale part 5 to rotate, the numerical value on the scale part 5 is the numerical value of the distance between the compass needle 20 and the lead core 30, and the step of measuring the compass needle 20 and the lead core 30 by the ruler is omitted, and the circle drawing efficiency is improved.

Referring to fig. 9 and 10, a fixing portion 71 may be disposed on the lead foot 3, an automatic core-ejecting mechanism 7 may be detachably connected to the fixing portion 71 by a screw thread, the lead 30 is disposed on the automatic core-ejecting mechanism 7, the automatic core-ejecting mechanism 7 is a known device, and chinese patent application No. may be adopted: 201620210748.9, the disclosed smart pencil for propelling lead; also can adopt other structures, no longer describe herein, adopt automatic mechanism 7 of loosing core, but the length of automatically regulated plumule 30 does not need the length of artifical manual regulation plumule 30, has improved the efficiency of drawing the circle, and can prevent that plumule 30 overlength or plumule 30 are too short to lead the actual distance of plumule 30 lower extreme and the 20 lower extremes of compasses needle and the distance on the scale 5 to produce certain error, and the setting of automatic mechanism 7 of loosing core makes the compasses can draw more accurate circle.

While the invention has been particularly shown and described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.