Round mapper for circle cutting

Abstract

The utility model provides a circle mapper for circle cutting, which comprises a body, a sliding chute is arranged in the middle of the body, a circle center positioning component is arranged in the sliding chute, the circle center positioning component can translate along the track of the sliding chute or is in positioning connection with the sliding chute, one end of the body is provided with a paper cutting component, and the other end of the body is connected with the paper cutting component. The paper cutting assembly comprises a blade capable of stretching out or retracting back. When the circle center positioning assembly is connected with the sliding groove in a positioning mode, the body can rotate around the central axis of the circle center positioning assembly. Extension or retraction of the blade is controlled through movement of the hand pushing block, the circle center positioning assembly on the body is matched, the circle cutting stability and precision can be improved, and operation is easy.

Description

TECHNICAL FIELD

[0001] The utility model relates to technical field of drawing tool, specifically, relate to a circular drawing device for cutting circle. BACKGROUND

[0002] The circular drawing device is a drawing tool for drawing a circle, and a common circular drawing device includes a compass.

[0003] The existing patent application document with the publication number CN107662232A discloses a paper cutter capable of cutting a circle. The side end of the paper cutter is provided with an openable fixing support. When a circular pattern needs to be cut, the support on the paper cutter can be opened, and the paper cutter can be cut along the support to obtain a complete circular pattern.

[0004] The existing paper cutter capable of cutting a circle has unstable center positioning, large cutting error, and needs to be improved. CONTENT OF THE UTILITY MODEL

[0005] In view of the defects in the prior art, the utility model aims at providing a circular drawing device for cutting circle.

[0006] According to the circular drawing device for cutting circle, the center positioning assembly can be positioned on the slide groove, and the body can rotate around the center axis of the center positioning assembly.

[0007] Preferably, a scale is arranged on the body, and the scale takes the position of the blade as the starting point of the scale.

[0008] Preferably, the center positioning assembly comprises a positioning column with a base, a fixing seat, a positioning sheet and an adjusting cap.

[0009] The fixing seat comprises a base arranged below the slide groove and a hollow column body with external threads, the fixing seat is rotationally sleeved on the positioning column, and the base of the fixing seat is arranged on the base of the positioning column.

[0010] The positioning sheet is arranged above the slide groove, the adjusting cap is arranged on the upper surface of the positioning sheet, and the positioning column and the hollow column body of the fixing seat pass through the slide groove and the positioning sheet in sequence upwards.

[0011] The internal threads of the adjusting cap are threadedly connected with the external threads of the hollow column body of the fixing seat, so that the fixing seat, the base and the positioning sheet are tightly matched or loosely matched with the slide groove.

[0012] The top of the positioning column extends upwardly through the hollow column of the fixing base and the adjusting cap.

[0013] Preferably, the positioning column is a hollow column extending through from top to bottom, and a push cap is fixedly connected to the top of the positioning column. The top surface of the push cap is made of transparent material, and the top of the push cap is provided with a central mark.

[0014] Preferably, the end of the body is connected with a plastic cover, and the end of the body is further provided with a long arm, and the long arm extends into the internal region of the plastic cover and is provided with a containing area.

[0015] The paper cutting assembly comprises a cutter head assembly and a hand pushing block. The cutter head assembly is installed in the containing area of the long arm, and the hand pushing block is movably arranged on the plastic cover. The bottom of the hand pushing block extends into the interior of the plastic cover, and the bottom of the hand pushing block is formed with a driving slope.

[0016] The cutter head assembly comprises a cutter holder seat, a cutter holder cover and a cutter blade holder. The cutter holder seat and the cutter holder cover form a middle cavity accommodating the cutter blade holder. A compression spring is arranged between the cutter blade holder and the cutter holder seat. The extension direction of the compression spring is the direction in which the cutter blade holder moves away from or approaches the bottom of the cutter holder seat. The cutter blade holder partially extends out of the middle cavity. The part of the cutter blade holder located in the middle cavity is fixed with a cutter blade. The bottom of the cutter holder seat is provided with a cutter outlet allowing the cutter blade to extend out or retract. The part of the cutter blade holder extending out of the middle cavity is formed with a driven slope. The driving slope and the driven slope are in contact.

[0017] Preferably, the hand pushing block moves on the plastic cover, and the driving slope and the driven slope move relative to each other, thereby pushing the cutter blade holder to move in the direction approaching the bottom of the cutter holder seat, the cutter blade extends out of the cutter outlet, and the compression spring is compressed.

[0018] The hand pushing block is reset, the compression spring is reset, and the cutter blade holder moves upwardly under the action of the compression spring to retract the cutter blade from the cutter outlet.

[0019] Preferably, the plastic cover is provided with a positioning portion, and the paper cutting assembly further comprises a rotating cover fixed on the positioning portion.

[0020] Preferably, the plastic cover is provided with a slot, and the bottom of the hand pushing block extends into the interior of the rotating cover through the slot.

[0021] Preferably, the hand pushing block located in the interior of the plastic cover is provided with a pin hole, and a split pin is inserted into the pin hole of the hand pushing block to prevent the hand pushing block from falling off.

[0022] Preferably, one end of the cutter blade holder is provided with a mandrel, and the cutter blade is clamped by the mandrel and a mandrel cover. The mandrel and the mandrel cover are fixedly connected by a screw.

[0023] Compared with the prior art, the utility model has the beneficial effects as follows:

[0024] 1、 the utility model discloses a hand -pushing piece's movement is controlled the extension or retraction of blade, cooperate the centring component on the body, help to improve the stability and precision of cutting circle, and simple operation. BRIEF DESCRIPTION OF DRAWINGS

[0025] Other features, objects and advantages of the utility model will become more apparent through reading the following detailed description of the non-restrictive embodiments with reference to the accompanying drawings:

[0026] Figure 1 It is the schematic diagram of the overall structure of cutting circle circular drawing device that the utility model mainly embodies;

[0027] Figure 2 It is the exploded view of the overall structure of cutting circle circular drawing device that the utility model mainly embodies;

[0028] Figure 3 It is the sectional view of the overall structure of tool head subassembly that the utility model mainly embodies;

[0029] Figure 4 It is the shaft side schematic diagram of the overall structure of tool head subassembly that the utility model mainly embodies;

[0030] Figure 5 It is the schematic diagram of the bottom structure of circular drawing device that the utility model mainly embodies;

[0031] Figure 6 It is the axial section schematic diagram of the overall structure of cutting circle circular drawing device that the utility model mainly embodies;

[0032] Figure 7 It is the cutting circle schematic diagram of circular drawing device that the utility model mainly embodies;

[0033] Figure 8 It is the schematic diagram of the overall structure of drawing circle circular drawing device that the utility model mainly embodies;

[0034] Figure 9 It is the exploded view of the overall structure of drawing assembly that the utility model mainly embodies;

[0035] Figure 10 It is the axial section schematic diagram of the overall structure of drawing circle circular drawing device that the utility model mainly embodies;

[0036] Figure 11 It is the drawing circle schematic diagram of circular drawing device that the utility model mainly embodies.

[0037] In the drawing:

[0038] Body 1 Cap 26 Blade holder 53

[0039] Chute 11 Plastic cover 3 Mandrel 531

[0040] Backrest 12 Slot 31 Mandrel cover 532

[0041] Long arm 13 Guide slot 32 Screw 533

[0042] Accommodation area 131 Extension plate 33 Blade 534

[0043] Slide 132 Groove 331 Driven slope 535

[0044] Hook 1321 Limiting baffle 34 Compression spring 54

[0045] Lock block 141 Rotating cover 35 Mounting hole 61

[0046] Pressing part 142 Screw 36 Notch 611 Projection 143 Positioning part 37 Upper positioning collet 62 Bottom cover 144 Hand pushing block 41 Positioning buckle 621 Screw 145 Driven slope 42 Hopper-shaped positioning clamp 622 Spring 146 Bore 43 Lower positioning collet 63 Middle baffle 15 Cotter pin 44 Annular outer edge wall 631 Positioning column 21 Knife holder seat 51 Split type clamp 632 Anti-skid pad 22 Knife outlet 511 Circle 100

[0047] Fixed seat 23 Knife holder cover 52 Circle 200

[0048] Positioning piece 24 Anti-skid projection 521 Drawing pen 201

[0049] Adjusting cap 25 DETAILED DESCRIPTION

[0050] The utility model will be described in detail below in combination with specific embodiments. The following embodiments will help those skilled in the art to further understand the utility model, but do not limit the utility model in any form. It should be pointed out that, for those skilled in the art, without departing from the concept of the utility model, a number of changes and improvements can be made. These all belong to the protection scope of the utility model.

[0051] As Figures 1 to 11 shown, according to the utility model provides a kind of cutting circle, drawing circle replaceable circular plotter, including body 1, the middle part of body 1 is equipped with chute 11, chute 11 is equipped with center positioning assembly, center positioning assembly can be along the track of chute 11 translation or with chute 11 positioning connection.

[0052] One end of the main body 1 is detachably fitted with a paper cutting assembly, which includes an extendable or retractable blade 534.

[0053] Alternatively, a drawing component may be detachably mounted on one end of the main body 1, and the drawing component may be detachably clamped with a drawing pen 201.

[0054] Alternatively, a paper-cutting component may be detachably installed at one end of the main body 1, and a drawing component may be detachably installed at the other end of the main body 1.

[0055] It should be noted that the technical solution of this application uses a center positioning component to determine the rotation center of the circular drafting device, and the paper cutting component and / or drawing component are detachably installed at the end of the main body 1 to realize the paper cutting function or drawing function of the circular drafting device. When the center positioning component is positioned and connected with the slide 11, the main body 1 can rotate around the central axis 531 of the center positioning component.

[0056] It needs to be further explained that,

[0057] In one feasible implementation: the paper cutting component and the drawing component of this application can be designed as separate replaceable part modules. When the paper cutting function is required, the paper cutting component part module is fixedly connected to the end of the body 1. When the drawing function is required, the paper cutting component part module is first removed, and then the drawing component part module is fixedly connected to the end of the body 1.

[0058] In another feasible implementation: the paper cutting component and the drawing component are detachably mounted at both ends of the body 1.

[0059] In another feasible implementation: the paper cutting component and the drawing component are integrated into a single part module, and the part module having the paper cutting component and the drawing component is detachably connected to the end of the body 1.

[0060] It should be further noted that, in the above three embodiments, only the installation positions of the paper cutting component and the drawing component are different. The combination of the paper cutting component and the drawing component in other positions all fall within the protection scope of the technical solution of this application.

[0061] like Figures 1 to 7 As shown, specifically, the circular drafting device includes a body 1, with a groove 11 in the middle of the body 1. A center positioning component that allows a view of the bottom is disposed within the groove 11. A plastic cover 3 is detachably connected to one end of the body 1. The plastic cover 3 is provided with a paper cutting component for mounting the blade 534, and / or a drawing component for fixing the drawing pen 201. More specifically, the plastic cover 3 is arched and snapped into the end of the body 1. The end of the body 1 with the plastic cover 3 has a raised backrest 12, the outer contour of which is adapted to the arched plastic cover 3.

[0062] Further, the center positioning assembly comprises a positioning column 21 with a base, a fixing seat 23, a positioning sheet 24 and an adjusting cap 25. The fixing seat 23 comprises a base arranged below the sliding groove 11 and a hollow column body with external threads, the fixing seat 23 is coaxially arranged on the positioning column 21, and the base of the fixing seat 23 is arranged on the base of the positioning column 21. The positioning sheet 24 is arranged above the sliding groove 11, the adjusting cap 25 is arranged on the upper surface of the positioning sheet 24, and the hollow column body of the positioning column 21 and the fixing seat 23 passes through the sliding groove 11 and the positioning sheet 24 in sequence from bottom to top. The internal threads of the adjusting cap 25 are threadedly connected with the external threads of the hollow column body of the fixing seat 23, so that the fixing seat 23 and the base and the positioning sheet 24 are tightly or loosely fitted with the sliding groove 11; the top of the positioning column 21 extends upwardly and passes through the hollow column body of the fixing seat 23 and the adjusting cap 25.

[0063] In a preferred embodiment, the positioning column 21 is a hollow column body penetrating from top to bottom, the top of the positioning column 21 is fixedly connected with a press cap 26, the top surface of the press cap 26 is made of transparent material, and the top of the press cap 26 is provided with a center mark. The position of the center positioning point can be visually observed during use. In addition, an anti-skid pad 22 is arranged at the bottom of the positioning column 21.

[0064] Further, the body 1 and the plastic cover 3 are detachably fixedly connected through a lock assembly. The lock assembly comprises a lock block 141, a pressing part 142, a protrusion 143, a spring 146, a middle baffle 15 and a groove 331. The middle baffle 15 is fixedly installed in the body 1, the lock block 141 is slidingly arranged in the body 1, the spring 146 is arranged between the lock block 141 and the middle baffle 15, and the extension direction of the spring 146 is the same as the sliding direction of the lock block 141. The pressing part 142 is fixedly connected with the lock block 141, one end of the pressing part 142 extends out of the body 1, the protrusion 143 is arranged on the pressing part 142 and / or the lock block 141, and the groove 331 is arranged on the plastic cover 3. Under the elastic force of the spring 146, the protrusion 143 is locked with the groove 331, and the plastic cover 3 is fixedly connected with the body 1; under the action of external force, the pressing part 142 moves into the body 1, so that the protrusion 143 is locked with the groove 331, and the plastic cover 3 is detachable from the body 1. In order to improve the stability of the detachable structure, the lock assembly is arranged on both sides of the width of the body 1. Specifically, the outer end of the lock block 141 is provided with the pressing part 142 which extends out of the side wall of the body 1. The middle of the bottom of the body 1 is provided with the middle baffle 15, and the spring 146 is arranged between the middle baffle 15 and the inner end of the lock block 141; the edge of the pressing part 142 is provided with the protrusion 143, and the two sides of the arched plastic cover 3 are provided with the extension plate 33, and the extension plate 33 is provided with the groove 331 matched with the protrusion 143. In order to prevent the lock assembly from falling off during use, the bottom of the body 1 is provided with a bottom cover 144, and the bottom cover 144 is fixedly connected with the body 1 through the screw 36145. When the groove 331 is engaged with the protrusion 143, the plastic cover 3 is connected with the body 1, and when the pressing part 142 is subjected to inward external force, the lock block 141 moves horizontally towards the middle baffle 15, and the protrusion 143 moves out of the groove 331. When the groove 331 is matched with the protrusion 143, the plastic cover 3 is matched with the body 1, and the arched plastic cover 3 can be separated from the body 1 by pulling horizontally.

[0065] Further, the end of the body 1 is provided with a long arm 13, the long arm 13 extends into the plastic cover 3, the outer wall of the long arm 13 is provided with a sliding strip 132 extending along the length direction of the body 1, the inner wall of the plastic cover 3 is provided with a guide groove 32 matched with the sliding strip 132. The end of the guide groove 32 close to the body 1 is provided with a limiting block 34, the end of the sliding strip 132 away from the body 1 is provided with a hook portion 1321, the hook portion 1321 and the limiting block 34 are limited in the length direction of the body 1. In order to prevent the arched plastic cover 3 from falling off when it is loosely matched with the body 1 during incomplete disassembly (when replacing the cutter head assembly), the outer end of the guide groove 32 is provided with a limiting block 34, and the free end of the sliding strip 132 is provided with a hook portion 1321 matched with the limiting block 34. Because the arched plastic cover 3 has a certain flexibility, when complete disassembly is needed (when replacing the function group), the side wall of the arched plastic cover 3 is moderately bent outward, so that the limiting block 34 and the hook portion 1321 are completely separated.

[0066] Further, the end of the body 1 is provided with a long arm 13, the long arm 13 extends into the plastic cover 3, the outer wall of the long arm 13 is provided with a sliding strip 132 extending along the length direction of the body 1, the inner wall of the plastic cover 3 is provided with a guide groove 32 matched with the sliding strip 132. The end of the guide groove 32 close to the body 1 is provided with a limiting block 34, the end of the sliding strip 132 away from the body 1 is provided with a hook portion 1321, the hook portion 1321 and the limiting block 34 are limited in the length direction of the body 1. In order to prevent the arched plastic cover 3 from falling off when it is loosely matched with the body 1 during incomplete disassembly (when replacing the cutter head assembly), the outer end of the guide groove 32 is provided with a limiting block 34, and the free end of the sliding strip 132 is provided with a hook portion 1321 matched with the limiting block 34. Because the arched plastic cover 3 has a certain flexibility, when complete disassembly is needed (when replacing the function group), the side wall of the arched plastic cover 3 is moderately bent outward, so that the limiting block 34 and the hook portion 1321 are completely separated.

[0067] In one possible implementation, the cutting assembly includes a cutter head assembly, a push block 41, and a rotating cover 35. The top of the plastic cover 3 includes a slot 31 for inserting the push block 41, and a positioning portion 37 for fixing the rotating cover 35, which is fixed on the positioning portion 37 by a screw 36. The bottom of the push block 41 extends to the inside of the rotating cover 35 through the slot 31 and is opposite to the cutter head assembly. The push block 41 inside the plastic cover 3 is provided with a pin hole 43, and the pin hole 43 of the push block 41 is inserted with a split pin 44 to prevent the push block 41 from falling off. After the push block 41 is inserted into the arched plastic cover 3, the pin hole 43 of the push block 41 is inserted with the split pin 44 to prevent the push block 41 from falling off. The bottom of the push block 41 forms an active slope 42, and the surface opposite to the active slope 42 on the cutter head assembly is provided with a driven slope 535. When the push block 41 moves horizontally, the active slope 42 pushes the driven slope 535, causing the blade 534 on the cutter head assembly to extend out of the bottom of the body 1, enabling cutting of a circle. Specifically, the cutter head assembly includes a cutter holder seat 51 and a cutter holder cover 52, and a middle cavity is formed between the cutter holder seat 51 and the cutter holder cover 52. The middle cavity contains a blade holder 53, one end of the blade holder 53 is provided with a mandrel 531, and the blade 534 is clamped by the mandrel 531 and a mandrel cover 532, and the mandrel 531 and the mandrel cover 532 are connected by a screw 533. In addition, the other end of the blade holder 53 outside the middle cavity forms the driven slope 535, and a compression spring 54 is arranged between the inner wall of the blade holder 53 at the lower part of the driven slope 535 and the bottom wall of the cutter holder seat 51. The bottom of the cutter holder seat 51 is provided with a blade outlet 511. The active slope 42 pushes the driven slope 535 downward, driving the blade holder 53 to move downward relative to the cutter holder seat 51, so that the lower edge of the blade 534 is exposed at the blade outlet 511. The blade 534 in this embodiment can be replaced with different styles as needed. In order to facilitate disassembly and replacement, anti-slip protrusions 521 are arranged at both ends of the cutter holder cover 52. In addition, a scale is arranged on the body 1 starting from the position of the blade 534, which facilitates radius positioning according to the size of the circle to be cut. In use, the blade 534 is pushed downward by pushing the push block 41, the adjusting cap 25 is loosened, the center positioning assembly is slid to the desired radius position, the adjusting cap 25 is tightened again to lock the center positioning assembly and anchor the radius size. One hand presses the cap 26 downward to position the center, and the other hand holds the rotating cover 35 to rotate the body 1 around the center positioning assembly to cut a circle 100.

[0068] In one possible implementation, when the product only has a circle cutting function, the plastic cover 3 can be fixedly installed at the end of the body 1.

[0069] As Figures 8 to 11Further, the drawing assembly further comprises an upper positioning sleeve 62 and a lower positioning sleeve 63, the plastic cover 3 is provided with a mounting hole 61, the upper positioning sleeve 62 and the lower positioning sleeve 63 are clamped with the side wall of the mounting hole 61, the upper positioning sleeve 62 and / or the lower positioning sleeve 63 are provided with elastic clamping pieces for clamping the drawing pen 201, and the elastic clamping pieces allow the drawing pen 201 to pass through the upper positioning sleeve 62 and the lower positioning sleeve 63.

[0070] In a feasible embodiment: regarding the drawing assembly, the top of the plastic cover 3 is provided with a mounting hole 61 for clamping the upper positioning sleeve 62 and the lower positioning sleeve 63. The edge of the mounting hole 61 is provided with a notch 611. The upper positioning sleeve 62 comprises an annular outer ring and a funnel-shaped positioning clamping piece 622 arranged inside the annular outer ring; the annular outer ring is provided with an outwardly turned positioning buckle 621, which is matched with the notch 611, so as to realize the clamping of the upper positioning sleeve 62 with the arched plastic cover 3. The lower positioning sleeve 63 comprises an annular outer edge wall 631 clamped with the mounting hole 61, the other end of the annular outer edge wall 631 extends to the inner side of the mounting hole 61 and is upwardly turned to form a split clamping piece 632, which forms a columnar structure surrounding the outer circumferential surface of the drawing pen 201. The plurality of U-shaped structures formed by the entire lower positioning sleeve 63 can realize the circumferential clamping of the drawing pen 201, adapt to various sizes and structures of the pen, and can ensure the clamping force to ensure that the drawing pen 201 does not move up and down during use. Preferably, the central axes 531 of the upper positioning sleeve 62 and the lower positioning sleeve 63 are collinear, which improves the stability of clamping the drawing pen 201. In addition, the body 1 is also provided with another scale ruler with the position of the drawing pen as the starting point, which facilitates the radius positioning according to the size of the to-be-drawn circle. In use, the adjusting cap 25 is loosened, the center positioning assembly is slid to the required radius position, and the adjusting cap 25 is tightened again. One hand presses the cap 26 downward to realize the center positioning, and the other hand holds the drawing pen 201 to drive the body 1 to rotate around the center positioning assembly to complete the drawing of the circle 200.

[0071] In the description of the present application, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0072] The specific embodiments of the present application are described above. It needs to be understood that the present application is not limited to the specific embodiments described above, and various changes or modifications can be made by those skilled in the art within the scope of the claims, which does not affect the essential content of the present application. In the case of no conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims

1. A circular drafting device for tangent circles, characterized in that, The device includes a main body, a groove in the middle of the main body, a center positioning component in the groove, the center positioning component being able to translate along the trajectory of the groove or be positioned and connected to the groove, and a paper cutting component at one end of the main body, the paper cutting component including a blade that can extend or retract. When the center positioning component is connected to the slide groove positioning, the body can rotate around the central axis of the center positioning component.

2. The circular drafting device for cutting circles as described in claim 1, characterized in that, The main body is provided with a scale, and the scale starts from the position of the blade.

3. The circular drafting device for cutting circles as described in claim 1, characterized in that, The center positioning assembly includes a positioning post with a base, a fixing seat, a positioning piece, and an adjusting cap; The fixing seat includes a base disposed below the slide groove and a hollow column with external threads. The fixing seat is rotatably sleeved on the positioning column, and the base of the fixing seat is disposed on the base of the positioning column. The positioning piece is positioned above the slide groove, the adjusting cap is positioned on the upper surface of the positioning piece, and the hollow column of the positioning post and the fixing seat passes through the slide groove and the positioning piece in sequence upwards. The internal thread of the adjusting cap is threadedly connected to the external thread of the hollow column in the fixed seat, so that the fixed seat, the base and the positioning piece are either tightly fitted or loosely fitted with the slide groove. The top of the positioning column extends upward through the hollow column of the fixing seat and the adjusting cap.

4. The circular drafting device for cutting circles as described in claim 3, characterized in that, The positioning post is a hollow column that runs vertically through the top and bottom. A cap is fixedly connected to the top of the positioning post. The top surface of the cap is made of transparent material, and a center mark is provided on the top of the cap.

5. The circular drafting device for cutting circles as described in claim 1, characterized in that, A plastic cover is connected to the end of the main body, and a long arm is also provided at the end of the main body. The long arm extends into the inner area of ​​the plastic cover and is provided with a receiving area. The paper cutting assembly includes a blade assembly and a push block. The blade assembly is installed in the receiving area of ​​the long arm, and the push block is movably mounted on the plastic cover. The bottom of the push block extends into the interior of the plastic cover, and the bottom of the push block forms an active ramp. The cutter head assembly includes a cutter holder, a cutter holder cover, and a blade holder. A central cavity for accommodating the blade holder is formed between the cutter holder and the cutter holder cover. A compression spring is provided between the blade holder and the cutter holder, and the compression spring extends or retracts in the direction that the blade holder moves away from or towards the bottom of the cutter holder. A portion of the blade holder extends out of the central cavity, and a blade is fixed to the portion of the blade holder located within the central cavity. The bottom of the cutter holder is provided with an outlet that allows the blade to extend or retract. A driven ramp is formed on the portion of the blade holder extending out of the central cavity, and the active ramp contacts the driven ramp.

6. The circular drafting device for tangent circles as described in claim 5, characterized in that, The push block moves on the plastic cover, the active ramp and the driven ramp move relative to each other, pushing the blade holder to move towards the bottom of the blade holder seat and extending the blade from the blade outlet, and the compression spring is compressed. The push block resets, the compression spring resets, and the blade holder moves upward under the action of the compression spring to retract the blade from the cutting edge.

7. The circular drafting device for cutting circles as described in claim 5, characterized in that, The plastic cover is provided with a positioning part, and the paper cutting assembly also includes a rotating cover, which is fixed on the positioning part.

8. The circular drafting device for cutting circles as described in claim 5, characterized in that, The plastic cover has a slot, and the bottom of the push block extends through the slot into the interior of the rotating cover.

9. The circular drafting device for tangent circles as described in claim 8, characterized in that, The push block located inside the plastic cover has a pin hole, and a cotter pin is inserted into the pin hole of the push block to prevent the push block from falling off.

10. The circular drafting device for cutting circles as described in claim 5, characterized in that, One end of the blade holder is provided with a spindle, and the blade is clamped by the spindle and the spindle cover. The spindle and the spindle cover are fixedly connected by screws.

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