CN209794993U - Teaching large-diameter compasses - Google Patents

Abstract

the utility model discloses a teaching large-diameter compasses, which comprises a rotating shaft, a main ruler, an auxiliary ruler, a steel needle, chalk inserting legs, a rotating sleeve, a compression spring and a nut, wherein the bottom of the outer wall of the rotating sleeve is provided with a plurality of supporting frames at intervals along the circumferential direction, and the free end of each supporting frame is respectively fixed with a holding piece; the nut is connected on the screw thread portion and the bottom of the nut abuts against the upper end face of the main scale, and the steel needle is sleeved on the second stepped hole in a sliding mode. By adopting the structure, after the circle center is fixed on the blackboard by the steel needle, the steel needle is fixed on the blackboard through the support frame, so that the circle center can not shift in the process of drawing a circle, and the rotating shaft and the chalk inserting leg are perpendicular to the blackboard surface, thereby effectively improving the stability of drawing the circle.

Description

Teaching large-diameter compasses

Technical Field

The utility model relates to a compasses field especially relates to teaching major diameter compasses.

Background

In the geometry is drawn, the compasses are in mathematics and drawing, be the instrument that is used for drawing circle or arc, the compasses that general teaching was used all include location foot and activity foot, the activity foot can rotate around the location foot, install the chalk on the activity foot, current location foot is the steel needle form generally, the compasses that this kind of teaching was used is at glass, it is wooden, plastics, skid easily on the blackboard of cement nature or the magnetite nature blackboard, unable fine location of centre of a circle and skid easily, and use the easy wear blackboard on the blackboard of teaching, because the location is inaccurate, the compasses that the teacher used all is difficult to the standard of drawing the figure, bring very big difficulty for the teaching.

Disclosure of Invention

An object of the utility model is to provide a teaching major diameter compasses that can effectively fix a position the centre of a circle.

In order to achieve the above purpose, the utility model adopts the following technical scheme:

the teaching large-diameter compasses comprise a rotating shaft, a main ruler, an auxiliary ruler, a steel needle and a chalk inserting leg, wherein the auxiliary ruler is sleeved on the main ruler in a sliding mode and is positioned on the main ruler through a locking piece, and the chalk inserting leg is vertically fixed at the bottom of the auxiliary ruler; the rotary shaft is characterized by further comprising a rotary sleeve, a compression spring and a nut, wherein a plurality of support frames are arranged at the bottom of the outer wall of the rotary sleeve at intervals along the circumferential direction, a suction piece is fixed at the free end of each support frame, a first stepped hole with a small upper part and a large lower part is arranged on the middle shaft part of the rotary sleeve along the axial direction of the rotary sleeve, the lower part of the rotary shaft is rotatably sleeved in the first stepped hole, a retaining ring is arranged at the bottom of the rotary shaft, and the retaining ring is limited at the shaft shoulder of the first stepped hole; the upper part of the rotating shaft is provided with a threaded part and a rotation stopping part from top to bottom, one end of the main scale is provided with a connecting hole matched with the shape of the rotation stopping part, the rotation stopping part is in sleeve fit with the connecting hole, the compression spring is sleeved on the rotating shaft, and two ends of the compression spring are respectively limited on the lower end surface of the main scale and the upper end surface of the rotating sleeve; the nut is connected to the threaded part, and the bottom of the nut abuts against the upper end face of the main scale; the middle shaft part of pivot is equipped with big end down's second shoulder hole along its axial, the steel needle slides and cup joints on the second shoulder hole, and the top of steel needle extends to the top of pivot and is equipped with first stopper, and the lower part of steel needle is equipped with the second stopper, and the second stopper is spacing in the shaft shoulder department of second shoulder hole.

The cross sections of the rotation stopping part and the connecting hole are square with the shapes matched with each other.

the chalk leg comprises a fixing sleeve, an expansion sleeve and chalk, a plurality of expansion gaps are formed in the side wall of the expansion sleeve at equal intervals along the circumferential direction, the top of the expansion sleeve is fixed to the bottom of the auxiliary ruler, the chalk is inserted into the expansion sleeve, and the fixing sleeve is sleeved outside the expansion sleeve and used for clamping the chalk.

The holding piece is a magnet or a sucker.

The utility model adopts the above technique, have following intentional effect:

1. After the circle center is fixed on the blackboard by the steel needle, the steel needle is fixed on the blackboard through the support frame, so that the circle center can not shift in the process of drawing a circle, and the rotating shaft and the chalk inserting leg are perpendicular to the blackboard surface, thereby effectively improving the stability of drawing the circle.

2. After the chalk is consumed, the nut is screwed down or the main ruler is slightly pressed down by hand, so that a certain contact force between the chalk and the blackboard can be ensured.

Drawings

The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments;

FIG. 1 is a perspective view of the teaching compasses of the present invention;

FIG. 2 is a front view of the teaching compasses of the present invention;

Fig. 3 is a sectional view taken along line a-a of fig. 2.

Detailed Description

As shown in one of fig. 1-3, the teaching large-diameter compasses of the utility model comprises a rotating shaft 1, a main ruler 2, an auxiliary ruler 3, a steel needle 4 and a chalk inserting leg 5, wherein the auxiliary ruler 3 is sleeved on the main ruler 2 in a sliding manner and is positioned on the main ruler 2 through a locking piece 6, and the chalk inserting leg 5 is vertically fixed at the bottom of the auxiliary ruler 3; the rotating shaft further comprises a rotating sleeve 7, a compression spring 8 and a nut 9, a plurality of support frames 10 are arranged at the bottom of the outer wall of the rotating sleeve 7 at intervals along the circumferential direction, a suction piece 11 is fixed at the free end of each support frame 10, a first stepped hole with a small upper part and a large lower part is arranged on the middle shaft part of the rotating sleeve 7 along the axial direction of the rotating sleeve, the rotating sleeve 7 at the lower part of the rotating shaft 1 is connected in the first stepped hole, a baffle ring 101 is arranged at the bottom of the rotating shaft 1, and the baffle ring 101 is limited at the shaft shoulder of the first stepped hole; the upper part of the rotating shaft 1 is provided with a threaded part 102 and a rotation stopping part 103 from top to bottom, one end of the main scale 2 is provided with a connecting hole matched with the rotation stopping part 103 in shape, the rotation stopping part 103 is in sleeve fit with the connecting hole, the compression spring 8 is sleeved on the rotating shaft 1, and two ends of the compression spring 8 are respectively limited on the lower end surface of the main scale 2 and the upper end surface of the rotating sleeve 7; the nut 9 is connected to the threaded part 102, and the bottom of the nut 9 abuts against the upper end face of the main ruler 2; the middle shaft part of the rotating shaft 1 is provided with a second stepped hole which is big end down along the axial direction, the steel needle 4 is sleeved on the second stepped hole in a sliding mode, the top of the steel needle 4 extends to the upper part of the rotating shaft 1 and is provided with a first limiting block 401, the lower part of the steel needle 4 is provided with a second limiting block 402, and the second limiting block 402 is limited at the shaft shoulder of the second stepped hole.

The cross sections of the rotation stopping part 103 and the connecting hole are respectively square with the shape matched with each other. This arrangement ensures that no relative movement occurs between the main scale 2 and the spindle 1.

the chalk inserting leg 5 comprises a fixing sleeve 51, an expansion sleeve 52 and chalk 53, a plurality of expansion gaps are formed in the side wall of the expansion sleeve 52 at equal intervals along the circumferential direction, the top of the expansion sleeve 52 is fixed at the bottom of the auxiliary ruler 3, the chalk 53 is inserted into the expansion sleeve 52, and the fixing sleeve 51 is sleeved outside the expansion sleeve 52 and used for clamping the chalk 53. The chalk 53 is clamped by adopting the expansion and fixing way of holding the fixing sleeve tightly, the clamping is reliable and stable, and the replacement is also convenient.

the utility model discloses in, holding piece 11 is the magnet of high magnetic force for the magnetism blackboard. In addition, the holder 11 may be a suction cup on a nonmagnetic blackboard.

The utility model discloses a theory of operation: 1. adjusting the radius: moving the auxiliary ruler 3 according to the radius of the drawn circle and locking and positioning; 2. centering: after the steel needle 4 moves towards the direction close to the blackboard to determine the center position of the circle, the support frame 10 moves towards the blackboard and is fixedly sucked on the blackboard, and then the main ruler 2 is turned to draw the circle on the blackboard.

After the circle center of the steel needle 4 is fixed on the blackboard through the support frame 10, the circle center can not be displaced in the process of drawing a circle, and the rotating shaft 1 and the chalk inserting leg 5 are perpendicular to the blackboard surface, so that the stability of drawing the circle is effectively improved.

In addition, when the chalk 53 is consumed, the nut 9 is tightened or the main scale 2 is lightly pressed by hand downward, so that a certain contact force between the chalk 53 and the blackboard can be ensured.

Claims (4)

1. The teaching large-diameter compasses comprise a rotating shaft, a main ruler, an auxiliary ruler, a steel needle and a chalk inserting leg, wherein the auxiliary ruler is sleeved on the main ruler in a sliding mode and is positioned on the main ruler through a locking piece, and the chalk inserting leg is vertically fixed at the bottom of the auxiliary ruler; the method is characterized in that: the rotary shaft is characterized by further comprising a rotary sleeve, a compression spring and a nut, wherein a plurality of support frames are arranged at the bottom of the outer wall of the rotary sleeve at intervals along the circumferential direction, a suction piece is fixed at the free end of each support frame, a first stepped hole with a small upper part and a large lower part is arranged on the middle shaft part of the rotary sleeve along the axial direction of the rotary sleeve, the lower part of the rotary shaft is rotatably sleeved in the first stepped hole, a retaining ring is arranged at the bottom of the rotary shaft, and the retaining ring is limited at the shaft shoulder of the first stepped hole; the upper part of the rotating shaft is provided with a threaded part and a rotation stopping part from top to bottom, one end of the main scale is provided with a connecting hole matched with the shape of the rotation stopping part, the rotation stopping part is in sleeve fit with the connecting hole, the compression spring is sleeved on the rotating shaft, and two ends of the compression spring are respectively limited on the lower end surface of the main scale and the upper end surface of the rotating sleeve; the nut is connected to the threaded part, and the bottom of the nut abuts against the upper end face of the main scale; the middle shaft part of pivot is equipped with big end down's second shoulder hole along its axial, the steel needle slides and cup joints on the second shoulder hole, and the top of steel needle extends to the top of pivot and is equipped with first stopper, and the lower part of steel needle is equipped with the second stopper, and the second stopper is spacing in the shaft shoulder department of second shoulder hole.

2. The teaching large diameter compass of claim 1, wherein: the cross sections of the rotation stopping part and the connecting hole are square with the shapes matched with each other.

3. The teaching large diameter compass of claim 1, wherein: the chalk leg comprises a fixing sleeve, an expansion sleeve and chalk, a plurality of expansion gaps are formed in the side wall of the expansion sleeve at equal intervals along the circumferential direction, the top of the expansion sleeve is fixed to the bottom of the auxiliary ruler, the chalk is inserted into the expansion sleeve, and the fixing sleeve is sleeved outside the expansion sleeve and used for clamping the chalk.

4. The teaching large diameter compass of claim 1, wherein: the holding piece is a magnet or a sucker.