CN105825765A - Flexibly drawn straight line three-side projection demonstration board - Google Patents

Abstract

A linear three-sided projection demonstration board with flexible traction, which is composed of a projection board, a projection connection mechanism, and a linear projection mechanism; the projection connection mechanism driven by a flexible rope ensures that the front projection and the horizontal projection connection of the linear moving point are vertical X-axis, the front projection and side projection of the moving point of the straight line ensure the vertical Z-axis; the retractable linear projection mechanism is adopted to make the projection length of the straight line changeable to meet the conditions of various positions of the straight line in space; the scale is provided on the translation frame and value, so that the distance from the horizontal projection of the reference moving point to the X-axis is equal to the distance from the side projection to the Z-axis. When in use, loosen the three projection caps by hand, move the three moving points one by one to the designated position and then tighten the projection caps. The present invention replaces seven constant teaching aids with one dynamically changeable physical teaching aid, and the dynamic demonstration effect is significantly improved.

Description

Linear three-sided projection demonstration board for flexible traction

technical field

The invention relates to teaching and demonstration teaching aids, in particular to a flexible traction linear three-sided projection demonstration board used in engineering drawing courses.

Background technique

In the engineering drawing course, the spatial position of the straight line is determined by the projection on the three projection planes, that is, the front projection, horizontal projection and side projection of the straight line. The straight line is represented by a straight line segment containing two endpoints, and the same The connection line between the front projection and the horizontal projection of the endpoint is vertical to the X axis, and the connection line between the front projection and the side projection is vertical to the Z axis. The distance from the horizontal projection to the X axis is equal to the distance from the side projection to the Z axis. There are seven situations for the position of the space line relative to the projection surface, which are the normal line, the horizontal line, the lateral horizontal line, the normal vertical line, the plumb line, the lateral vertical line and the oblique line. In the teaching of engineering drawing courses, front projection, Horizontal and side projections demonstrate these seven straight lines, respectively. At present, these seven kinds of straight lines are demonstrated by using seven physical model teaching aids or drawing their three-sided projection diagrams on the blackboard. If physical model teaching aids are used, each teaching aid is fixed, and its disadvantage is that it is bulky, and it is inconvenient to carry, carry, move and hang. If it is used to draw its three-sided projection on the blackboard, it will take more time. , takes up a lot of space on the blackboard, and the dynamic presentation effect is not good. affect the quality of teaching.

Contents of the invention

In order to solve the above problems, the present invention provides a flexible traction linear three-sided projection demonstration board. The flexible traction linear three-sided projection demonstration board adopts the form of one end point of the straight line being fixed and the other end point movable, and the projection connection driven by flexible traction Mechanism and linear projection mechanism can not only conveniently, flexibly and quickly place 7 kinds of straight positions, but also ensure that the connection line between the front projection and horizontal projection of the end points of the straight line is vertical to the X axis, and the connection line between the front projection and side projection of the straight line end points is vertical Z axis. To solve the above-mentioned problems of the prior art.

The technical solution adopted by the present invention to solve the technical problem is: the flexible traction linear three-sided projection demonstration board includes a projection board, a projection connection mechanism, and a linear projection mechanism.

The projection board is provided with X axis, YH axis, Yw axis and Z axis, and the X axis, YH axis, Yw axis and Z axis divide the projection board into an orthographic projection plane, a horizontal projection plane, a side projection plane and a YHYw plane. There is an angle dividing line on the YHYw surface. Let the end points of the straight line segment be the fixed point and the moving point. The fixed point is a fixed point, and the orthographic projection surface, horizontal projection and side projection of the fixed point are set in the middle of the respective projection surfaces. The vertical X-axis of the connection line between the fixed-point orthographic projection and the horizontal projection is set as the left fixed-point projection connection; the vertical Z-axis of the connection between the fixed-point orthographic projection surface and the side projection is set as the upper fixed-point projection connection; the fixed-point horizontal projection The distance to the X axis is equal to the distance from the side projection of the fixed point to the Z axis. The line from the horizontal projection of the fixed point to the corner line is set as the lower fixed point projection line, and the line from the side projection of the fixed point to the corner line slide is set as the right fixed point. Projection connection. X-axis, YH-axis, Yw-axis, Z-axis, left fixed-point projection connection line, right fixed-point projection connection line, upper fixed-point projection connection line, lower fixed-point projection connection line and the cut-off surface of the angle dividing line are rectangular slots.

The projection connection mechanism includes a translation frame, a hanging wheel, a hanging wheel shaft, a pulley, a pulley shaft, a flexible rope, a rope frame and a rope frame screw. There are two translation racks, namely the upper translation rack and the left translation rack. The right half of the upper translation frame and the lower half of the left translation frame are provided with scales and values, so as to refer to the position of the side projection and side projection. The translation frame is a C-shaped bar structure, and the two ends of the translation frame are hooked on the projection board. The translation frame is provided with a bar-shaped positioning groove, and a slide groove is arranged on the positioning groove, and the slide groove is narrower than the positioning groove. The upper end of the left translation frame is provided with a hanging wheel shaft, and a hanging wheel is sleeved on the hanging wheel shaft, and the hanging wheel rides on the top of the projection plate. At the back of the projection board, pulley shafts are provided at both ends of all translation frames, and pulleys are set on the pulley shafts. The pulleys are provided with two slideways, and each slideway is wound with a flexible rope. There are four flexible ropes. Two flexible ropes are wound on the pulley, and the two ends of each flexible rope are respectively fixed on the rope holders on both sides of the projection board. There are eight rope racks, and the rope racks are symmetrically fixed on the corners of the four sides of the projection board by the rope rack screws. Each flexible rope goes around the pulley and turns to another pulley of the same translation frame, and then turns to connect with the rope frame, forming a Z or reverse Z shape; the fixation and direction of the other flexible rope opposite to it are symmetrical to the previous flexible rope , the winding directions of the two flexible ropes and the same pulley are opposite; to ensure that the translation frame can move in translation on the projection board.

The linear projection mechanism includes a fixed point, a moving point and a projection connection line. The fixed point includes a fixed point front projection, a fixed point horizontal projection and a fixed point side projection. Each projection is composed of a fixed point bearing, a fixed point cap, a fixed point shaft, a fixed point coil spring and a linear projection. The projection surface A fixed-point bearing is installed in the fixed-point slot on the upper surface, and the inner ring of the fixed-point bearing has a fixed-point cap, and a fixed-point opening is arranged on the fixed-point cap. A fixed-point shaft is fixedly installed, and a fixed-point coil spring is installed on the fixed-point shaft. The inner end of the fixed-point coil spring is connected to the fixed-point shaft, and the outer end of the fixed-point coil spring is connected to a linear projection. The linear projection is a flexible thin strip, which is divided into linear front projection. , straight-line horizontal projection and straight-line side projection, the straight-line projection is wound on the fixed-point coil spring, and the straight-line projection protrudes onto the projection plate through the fixed-point opening to connect with the moving point. The linear projection is always stretched straight on the projection plate under the pulling of the fixed-point coil spring, and the length is variable. The moving point includes the moving point front projection, the moving point horizontal projection and the moving point side projection, and each projection is composed of a slider, a projection clamp, a pin, a moving point shell, a moving point coil spring, a moving point projection connection line and a moving point cap . The slider is a combination of a cuboid and a cylinder. There is a cylindrical through hole in the cylinder of the slider. There are two projection clamps in the through hole. The projection clamp is a half-step cylindrical shape. The contact surface between the two projection clamps The linear projection is clamped inside, and the two projection clamps are connected by pins to form a stepped cylinder. The projection clamp can rotate in the cylindrical hole of the slider; the cuboid of the slider is placed in the positioning groove of the translation frame, and the slider can be placed in the positioning groove Slide inside; the cylinder on the slider is put into the chute of the translation frame. The outside of the cylinder of the slider in the front projection is connected to the inner ends of two parallel moving point coil springs, and the outer ends of the two moving point coil springs in the front projection of the moving point are respectively connected to the left moving point projection connection line and the upper moving point projection connection line , the outer cylinder of the horizontal projection and side projection of the moving point is connected to the inner end of a moving point coil spring, the outer side of the horizontally projected moving point coil spring is connected to the left moving point projection line, and the outer side of the side projected coil spring is connected to the upper moving point Point projection connection. The truncated surface of the moving point coil spring is circular. The outer side of the three projections of the moving point is covered with a moving point shell, which is provided with a round hole, and the moving point projection connection line passes through the hole to another moving point projection, and the moving point projection connection line is pulled by the moving point coil spring , always stretched straight on the projection board, and variable in length. The moving point cap is divided into a moving point front projection cap, a moving point horizontal projection cap and a moving point side projection cap. The moving point cap is screwed on the screw hole of the slider cylinder through threads, and the moving point projection is fixed and locked on the mobile frame. .

The projection surface is white, the projection connection lines and fonts are black, the translation frame is made of transparent materials, the moving and fixed points are made of red, and the linear projection is made of eye-catching colors.

The beneficial effects of the present invention are: adopting the projection connection mechanism driven by a flexible rope, so that the front projection and the horizontal projection connection line of the straight line moving point can ensure the vertical X axis, and the front projection and side projection of the straight line moving point can ensure the vertical Z axis; The retractable linear projection mechanism enables the projection length of the straight line to be changed to meet the conditions of various positions of the straight line in space. The present invention replaces seven constant teaching aids with one dynamically changeable physical teaching aid, and the dynamic demonstration effect is significantly improved.

Description of drawings

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

Fig. 1 is a front perspective view showing the overall structure.

Fig. 2 is a rear perspective view showing the overall structure.

Fig. 3 is a front view.

FIG. 4 is a left side view taken along AA on FIG. 3 .

Fig. 5 is a rear view taken along line BB in Fig. 4 .

Fig. 6 is a partial enlarged view of the moving point in Fig. 5 .

FIG. 7 is a rear view taken along CC in FIG. 4 .

Fig. 8 is an oblique sectional view taken along DD in Fig. 3 .

FIG. 9 is a partial sectional view taken along EE in FIG. 8 .

Figure 10 is an example of horizontal line projection.

Figure 11 is an example of orthographic projection.

Figure 12 is an example of a horizon projection.

Figure 13 is an example of a plumb line projection.

Fig. 14 is an embodiment of normal perpendicular projection.

Figure 15 is an example of a side perpendicular projection.

In the figure 1. projection board, 2. upper translation frame, 3. left moving point projection connection, 4. hanging wheel shaft, 5. left translation frame, 6. moving point front projection cap, 7. straight line front projection, 8. fixed point Front projection cap, 9. Upper fixed point projection connection, 10. Z axis, 11. Up moving point projection connection, 12. Chute, 13. Right fixed point projection connection, 14. Fixed point side projection cap, 15. Straight side Projection, 16. Scale, 17. Moving point side projection cap, 18. Yw axis, 19. Rope frame, 20. Rope frame screw, 21. Angle line, 22. YH axis, 23. Lower fixed point projection connection line, 24 .X axis, 25. Left fixed point projection connection line, 26. Fixed point horizontal projection cap, 27. Straight line horizontal projection, 28. Moving point horizontal projection cap, 29. Pulley shaft, 30. Pulley, 31. Moving point coil spring, 32 .Projection clamp block, 33. Flexible rope, 34. Hanging wheel, 35. Moving point shell, 36. Slider, 37. Positioning slot, 38. Pin, 39. Fixed point slot, 40. Fixed point shaft, 41. Fixed point coil spring , 42. fixed-point bearing, 43. fixed-point opening.

detailed description

Fig. 1 to Fig. 5 and Fig. 7 represent the connection and positional relationship of the overall structure composition and parts of the present invention, also are the embodiment of oblique line.

Figure 6 shows the composition of the moving point structure and the connection and positional relationship of the components.

Figure 8 shows the structural composition of the linear projection mechanism and the connection and positional relationship of the components.

Figure 9 shows the connection and positional relationship of fixed-point structure components and components.

In FIG. 1 to FIG. 9 , the flexible traction linear three-sided projection demonstration board includes a projection board 1 , a projection connection mechanism, and a linear projection mechanism.

The linear three-sided projection demonstration board with flexible traction includes a projection board 1, a projection connection mechanism, and a linear projection mechanism.

X-axis 24, YH-axis 22, Yw-axis 18 and Z-axis 10 are provided on projection board 1, and X-axis 24, YH-axis 22, Yw-axis 18 and Z-axis 10 divide projection board 1 into positive projection plane and horizontal projection plane , side projection plane and YHYw plane. Corner dividing line 21 is provided on YHYw surface. Let the end points of the straight line segment be the fixed point and the moving point. A fixed point is a fixed point, and the orthographic projection surface, horizontal projection and side projection of a fixed point are located in the middle of the respective projection surfaces, and the orthographic projection surface, horizontal projection and side projection of a fixed point are respectively provided with a fixed-point groove 39, and the fixed-point groove 39 is a stepped circle hole. The vertical X-axis 24 of the vertical projection surface of the fixed point and the horizontal projection is set as the left fixed-point projection connection 25; the vertical Z-axis 10 of the vertical projection surface and the side projection of the fixed point is set as the upper fixed-point projection connection 9; The distance from the horizontal projection of the fixed point to the X-axis 24 is equal to the distance from the side projection of the fixed point to the Z-axis 10, the horizontal projection of the fixed point to the angle line 21 is set as the lower fixed point projection line 23, and the side projection of the fixed point is to the angle line The line of 21 is set as the right fixed-point projection connection line 13. X-axis 24, YH-axis 22, Yw-axis 18, Z-axis 10, left fixed-point projection connection 25, right fixed-point projection connection 13, upper fixed-point projection connection 9, lower fixed-point projection connection 23 and angle division line 21 Faces are rectangular slots.

The projection connection mechanism includes a translation frame, a hanging wheel 34 , a hanging wheel shaft 4 , a pulley 30 , a pulley shaft 29 , a flexible rope 33 , a rope frame 19 and a rope frame screw 20 . Translation frame has two, is respectively upper translation frame 2 and left translation frame 5. The right half of the upper translation frame 2 and the lower half of the left translation frame 5 are provided with a scale 16 and a numerical value, with reference to the side projection and the position of the side projection. The translation frame is a C-shaped strip structure, and the two ends of the translation frame are hooked on the projection board 1 . The translation frame is provided with a strip positioning groove 37, and the positioning groove 37 is provided with a chute 12, and the chute 12 is narrower than the positioning groove 37. The upper end of the left translation frame 5 is provided with a hanging wheel shaft 4, and the hanging wheel shaft 4 is covered with a hanging wheel 34, and the hanging wheel 34 rides on the projection board 1 upper end. At the back of the projection board 1, pulley shafts 29 are respectively provided at both ends of all translation frames, and pulleys 30 are sleeved on the pulley shafts 29. The pulleys 30 are provided with two slideways, and each slideway is respectively wound with a flexible rope 33. There are four ropes 33 in total, and two flexible ropes 33 are wound on each pulley 30 , and the two ends of each flexible rope 33 are respectively fixed on the rope frames 19 on both sides of the projection board 1 . There are eight rope racks 19, and the rope racks 19 are symmetrically fixed on the corners of the four sides of the projection board 1 by the rope rack screws 20. Every flexible rope 33 turns to another pulley 30 of the same translation frame after walking around the pulley 30, and then turns to be connected with the rope frame 19, becomes Z or reverse Z shape; The first flexible rope 33 is symmetrical, and the winding directions of the two flexible ropes 33 and the same pulley 30 are opposite; so as to ensure that the translation frame can move in translation on the projection board 1 .

The linear projection mechanism includes fixed point, moving point and projection connection line, fixed point includes fixed point front projection, fixed point horizontal projection and fixed point side projection, each projection is made up of fixed point bearing 42, fixed point cap, fixed point shaft 40, fixed point coil spring 41 and linear projection , fixed-point bearing 42 is installed in the fixed-point slot 39 on the projection surface, and fixed-point cap is arranged on the outer ring of the inner ring of fixed-point bearing 42, and fixed-point cap is provided with fixed-point opening 43, and fixed-point cap is divided into fixed-point frontal projection cap 8, fixed-point horizontal projection cap 26 and Fixed-point side projection cap 14, fixed-point bearing 42 inner rings are fixedly installed with fixed-point shaft 40, fixed-point coil spring 41 is installed on the fixed-point shaft 40, the inner end of fixed-point coil spring 41 is connected with fixed-point shaft 40, and the outer end of fixed-point coil spring 41 is connected with fixed-point coil spring 40. Linear projection connection, the linear projection is a flexible thin strip, divided into linear front projection 7, linear horizontal projection 27 and linear side projection 15, the linear projection is wound on the fixed-point coil spring 41, and the linear projection protrudes to the projection board through the fixed-point opening 43 1, connected with the moving point. The linear projection is always stretched straight on the projection board 1 under the pulling of the fixed-point coil spring 41, and the length is variable. Moving point comprises moving point frontal projection, moving point horizontal projection and moving point side projection, and each projection is connected by slide block 36, projection clip 32, pin 38, moving point shell 35, moving point coil spring 31, moving point projection Composed with a dot cap. The slide block 36 is a combination of a cuboid and a cylinder. There is a cylindrical through hole in the cylinder of the slide block 36. Two projection clamps 32 are arranged in the through hole. The projection clamp 32 is a half-step cylinder, and the two projection clamps 32 Clamp the linear projection in the contact surface between them, two projection clamping blocks 32 are connected into stepped cylinder by pin 38, projection clamping block 32 can rotate in the cylindrical hole of slide block 36; The cuboid of slide block 36 is put into the translation frame In the positioning groove 37, the slider 36 can slide in the positioning groove 37; the cylinder on the slider 36 is put into the chute 12 of the translation frame. The outside of the cylinder of the slide block 36 of the front projection is connected with the inner ends of two parallel moving point coil springs 31, and the outer ends of the two moving point coil springs 31 of the front projection of the moving point are respectively connected to the left moving point projection connecting line 3 and the upper moving point. Point projection connecting line 11, the cylinder outside of the sliding block 36 of moving point horizontal projection and side projection is connected with the inner end of a moving point coil spring 31, and the outside of the moving point coil spring 31 of horizontal projection is connected with the left moving point projection connecting line 3, The outer side of the coil spring projected on the side is connected with the projection connecting line 11 of the upper moving point. The sectional surface of the moving point coil spring 31 is circular. The outside of the three projections of the moving point is covered with a moving point shell 35, and the moving point shell 35 is provided with a circular hole. Under the pull of pulling, always straighten on the projection board 1, and the length is variable. The moving point cap is divided into a moving point frontal projection cap 6, a moving point horizontal projection cap 28 and a moving point side projection cap 17, and the moving point cap is screwed on the screw hole of the slider 36 cylinder by threads to fix and lock the moving point projection on the mobile rack.

The projection surface is white, the projection connection lines and fonts are black, the translation frame is made of transparent materials, the moving and fixed points are made of red, and the linear projection is made of eye-catching colors.

When demonstrating the present invention, loosen point frontal projection cap 6, moving point horizontal projection cap 28 and moving point side projection cap 17 with hand rotation, move moving point frontal projection to designated position and tighten moving point frontal projection cap 6, to lock straight line The position of the frontal projection 7; move the horizontal projection of the moving point to the specified position and then tighten the horizontal projection cap 28 of the moving point to lock the position of the horizontal projection 27 of the straight line; read the scale value of the horizontal projection of the moving point on the left translation frame 5 again, Move the side projection of the moving point to the corresponding scale value position of the upper translation frame 2, and then tighten the side projection cap 17 of the moving point. When the moving point projection coincides with the fixed point projection, the fixed point projection cap can be pulled out to avoid interference between the fixed point and the moving point. This operation can demonstrate various positions of the straight line.

Figure 10 is an example of horizontal line projection.

Figure 11 is an example of orthographic projection.

Figure 12 is an example of a horizon projection.

Figure 13 is an example of a plumb line projection.

Fig. 14 is an embodiment of normal perpendicular projection.

Figure 15 is an example of a side perpendicular projection.

Claims (1)

1. A linear three-sided projection demonstration board for flexible traction, comprising a projection board, a projection connection mechanism, and a linear projection mechanism, characterized in that: the projection board is provided with an X axis, a YH axis, a Yw axis and a Z axis, and the X axis, The YH axis, the Yw axis and the Z axis divide the projection board into a positive projection plane, a horizontal projection plane, a side projection plane and a YHYw plane; the YHYw plane is provided with an angle dividing line; the end points of the straight line segments are set as fixed points and moving points; the fixed points are For a fixed point, the orthographic projection plane, horizontal projection and side projection of the fixed point are set in the middle of the respective projection planes, and the orthographic projection plane, horizontal projection and side projection of the fixed point are respectively provided with fixed-point slots, and the fixed-point slots are stepped circular holes; The vertical X-axis of the connection line between the orthographic projection surface and the horizontal projection is set as the left fixed-point projection connection; the vertical Z-axis connection of the fixed-point orthographic projection surface and the side projection is set as the upper fixed-point projection connection; the fixed-point horizontal projection is to X The distance of the axis is equal to the distance from the side projection of the fixed point to the Z axis. The line from the horizontal projection of the fixed point to the angle line is set as the lower fixed point projection connection line, and the line from the side projection of the fixed point to the angle line slide is set as the right fixed point projection connection. line; X-axis, YH-axis, Yw-axis, Z-axis, left fixed-point projection connection line, right fixed-point projection connection line, upper fixed-point projection connection line, lower fixed-point projection connection line and the cut-off surface of the angle division line are rectangular slots; projection connection The line mechanism includes a translation frame, a hanging wheel, a hanging wheel shaft, a pulley, a pulley shaft, a flexible rope, a rope frame and a rope frame screw; there are two translation frames, which are the upper translation frame and the left translation frame; There are scales and values on the lower half of the left translation frame, so as to refer to the position of horizontal projection and side projection; the translation frame is a C-shaped bar structure, and the two ends of the translation frame are hooked on the projection board; There is a bar-shaped positioning groove, and a chute is opened on the positioning groove, and the chute is narrower than the positioning groove; the upper end of the left translation frame is provided with a hanging wheel shaft, and the hanging wheel shaft is covered with a hanging wheel, and the hanging wheel rides on the top of the projection board; In the back, pulley shafts are respectively provided at both ends of all translation frames, and pulleys are sheathed on the pulley shafts. The pulleys are provided with two slideways, and each slideway is wound with a flexible rope. There are four flexible ropes, and each pulley is wound with a flexible rope. Two flexible ropes, the two ends of each flexible rope are respectively fixed on the rope holders on both sides of the projection board; there are eight rope holders, and the rope holders are symmetrically fixed on the corners of the four sides of the projection board by rope holder screws; The flexible rope goes around the pulley and turns to another pulley of the same translation frame, and then turns to connect with the rope frame to form a Z or reverse Z shape; The winding direction of the flexible rope and the same pulley is opposite; to ensure that the translation frame can move in translation on the projection board; the linear projection mechanism includes a fixed point, a moving point and a projection connection line, and the fixed point includes a fixed point front projection, a fixed point horizontal projection and a fixed point side projection. Each projection is composed of a fixed-point bearing, a fixed-point cap, a fixed-point shaft, a fixed-point coil spring and a linear projection. A fixed-point bearing is installed in a fixed-point slot on the projection surface. The inner ring of the fixed-point bearing is covered with a fixed-point cap. There is a fixed-point opening on the fixed-point cap. The fixed-point cap is divided into fixed-point front projection cap, fixed-point horizontal projection cap and fixed-point side projection cap. The inner ring of the fixed-point bearing is fixed with a fixed-point shaft, and a fixed-point coil spring is installed on the fixed-point shaft. The inner end of the fixed-point coil spring is connected with the fixed-point shaft. Connected, the outer end of the fixed-point coil spring is connected with the linear projection, the linear projection is a flexible thin strip, divided into linear front projection, linear horizontal projection and linear side projection, the linear projection is wound on the fixed-point coil spring, and the linear projection extends through the fixed-point opening Go out to the projection board and connect with the moving point; the straight line projection is always stretched straight on the projection board under the pull of the fixed-point coil spring, and the length is variable; the moving point includes the front projection of the moving point, the horizontal projection of the moving point and the side of the moving point Projection, each projection is composed of a slider, a projection clamp, a pin, a moving point shell, a moving point coil spring, a moving point projection connection line and a moving point cap; the slider is a combination of a cuboid and a cylinder, and the inside of the cylinder of the slider There is a cylindrical through hole, and there are two projection clamps in the through hole. The projection clamp is a half-step cylindrical shape. The contact surface between the two projection clamps clamps the linear projection. The two projection clamps are connected by pins. Stepped cylinder, the projection clamp can rotate in the cylindrical hole of the slider; the cuboid of the slider is placed in the positioning groove of the translation frame, and the slider can slide in the positioning groove; the cylinder on the slider is placed in the chute of the translation frame Inside; the outside of the cylinder of the front projection slider is connected to the inner ends of two parallel moving point coil springs, and the outer ends of the two moving point coil springs in the front projection of the moving point are respectively connected to the left moving point projection connection line and the upper moving point projection The connection line, the outer cylinder of the horizontal projection and side projection of the moving point is connected to the inner end of a moving point coil spring, the outer side of the horizontally projected moving point coil spring is connected to the left moving point projection connection line, and the outer side of the side projected coil spring is connected The projection connection line of the upper moving point; the truncated surface of the moving point coil spring is circular; the outer side of the three projections of the moving point is covered with a moving point shell, and a round hole is arranged on the moving point shell, and the moving point projection connection line passes through the hole to the other A moving point projection, the moving point projection connection line is always stretched straight on the projection board under the pull of the moving point coil spring, and the length is variable; the moving point cap is divided into a moving point front projection cap, a moving point horizontal projection cap and a moving point projection cap. The side projection cap of the moving point, the moving point cap is screwed on the screw hole of the slider cylinder through threads, and the moving point projection is fixed and locked on the mobile frame; the projection surface is white, the projection connection and font are black, and the translation frame is Transparent materials, moving and fixed points in red, and linear projections in eye-catching colors.