CN211138815U

CN211138815U - Compasses

Info

Publication number: CN211138815U
Application number: CN201920900451.9U
Authority: CN
Inventors: 刘晓燕; 王永林; 闫向洲
Original assignee: Individual
Current assignee: Individual
Priority date: 2019-06-07
Filing date: 2019-06-07
Publication date: 2020-07-31
Anticipated expiration: 2029-06-07

Abstract

A compasses belongs to teaching tools and solves the problems of inaccurate drawing and unreliable operation of the rubber bowl adsorption compasses; the technical scheme is as follows: comprises a central disc, a positioning cylinder, a positioning foot, a pull rod, a chalk clip and the like; the central disc takes a circular magnet as a main body, two pull rod holes are formed in the positioning cylinder, the pull rods are matched with the pull rod holes, and the pull rods are inserted into the two pull rod holes in a seamless mode and pulled; the positioning cylinder is also provided with a positioning screw hole and a positioning screw rod; a positioning pin is arranged below the positioning cylinder, a chalk clamp seat is arranged at one end of the pull rod, and the chalk clamp is fixedly embedded in the chalk clamp seat; the inner hole of the circle center disc is aligned with the circle center of a drawn circle, the positioning pin is inserted into the inner hole of the circle center disc, the pull rod is pulled to adjust the radius of the circle to be drawn, and the circle can be drawn by slightly pressing the positioning cylinder with one hand and rotating the pull rod with the other hand; when the line segment is cut, the circle center disk is not used, and the distance between the positioning foot and the chalk clip is equal to the length of the cut line segment. The drawing device is suitable for iron blackboards, and is accurate in drawing and reliable in operation.

Description

Compasses

Technical Field

Belong to the teaching articles for use field, especially relate to mathematical education apparatus.

Background

The existing blackboard is mostly an iron blackboard, the traditional compasses with iron points can not be used on the iron blackboard, and the colloid exhaust bowl of the existing exhaust adsorption type compasses has two problems, namely, the center of the colloid exhaust bowl is difficult to ensure to be exactly positioned at the center of a circle to be drawn, so that the position of the center of the circle to be drawn is incorrect. Secondly, the angle of the joint of the colloid exhaust bowl and the compass arm can be changed due to the change of the stress direction in the rotating process, so that the radius of the drawn circle is changed, and the drawn circle is not standard. The combined effect of the two aspects makes the mapping more non-canonical. Meanwhile, the exhaust bowl has the problem of unreliable operation in use, the prior patent application 201810743717.3 has a complex structure and high cost, is not suitable for students in the teaching process, and can be a vulnerable part when placed in a classroom for convenient teaching.

Disclosure of Invention

The utility model aims at providing a compasses convenient to use on iron blackboard.

The utility model adopts the technical proposal that: the compasses consist of a center disk, a positioning cylinder, a positioning foot, a pull rod, a positioning screw rod, a chalk clip and the like; the blackboard eraser is characterized in that the circular center plate takes a circular magnet as a main body, and a buckling concave position is reserved on the ring surface close to the blackboard, so that the circular center plate adsorbed on the blackboard can be conveniently taken down; the circular ring of the circular center plate is in a circular truncated cone shape, the small bottom surface of the circular truncated cone-shaped circular ring is close to the blackboard, the diameter of the small bottom surface of the circular truncated cone-shaped circular ring is equal to the diameter of the lower end of the positioning foot, and the included angle between the generatrix of the circular truncated cone-shaped circular ring and the axis is 30-70 degrees, so that the circular truncated cone-shaped circular ring of the circular center plate not only meets the function of controlling the positioning foot not to slide, but also meets the circular truncated cone-shaped space required in the rotating process of the positioning foot; the positioning barrel is of a cylindrical barrel structure, two pull rod holes are formed in the positioning barrel, the two pull rod holes are horizontally symmetrical to the center line of the positioning barrel, the pull rods are matched with the pull rod holes, and the pull rods are inserted into the two pull rod holes in a seamless penetrating mode and pulled; the positioning cylinder is also provided with a positioning screw hole and a positioning screw rod, and the positioning screw rod is screwed to fix the position of the pull rod relative to the positioning cylinder, so that the radius of the drawn circle is determined; a truncated cone-shaped positioning foot is arranged below the positioning cylinder, and the lower bottom of the truncated cone-shaped positioning foot is replaced by a spherical crown which is internally tangent to a truncated cone and is not more than a hemisphere; a chalk clamp seat is arranged at one end of the pull rod, the chalk clamp seat is cylindrical and concave, the inner diameter of the chalk clamp seat is equal to the outer diameter of the chalk clamp, and the chalk clamp is fixedly embedded into the chalk clamp seat; the chalk clamp is characterized in that a scale mark for marking the length is arranged on the upper surface of the pull rod by taking the position corresponding to the center of the chalk clamp seat as a starting point, a plus x mark is arranged on the side surface of the positioning cylinder towards the chalk clamp direction, wherein x is half of the outer diameter of the positioning cylinder, and the radius of a circle to be drawn is obtained by adding x to the number of scales at the joint of the pull rod and the positioning cylinder.

Furthermore, the surface of the annular magnet of the central disc, which is close to the blackboard, is attached with a colloid material for increasing friction, so that the static friction coefficient of the central disc and the blackboard surface is larger than 0.5.

Furthermore, the chalk clamp consists of a clamping sleeve and a tightening sleeve, the clamping sleeve is in a cylindrical shape with one open end and one closed end, the outer diameter of the closed end is equal to the inner diameter of the chalk clamp seat, the chalk clamp seat is embedded in the clamping sleeve, 3-6 axial gaps are arranged at equal intervals at the open end, the open end has an opening and closing function, and the clamping sleeve is sleeved with a locking sleeve.

The utility model discloses the beneficial effect who gains is: on an iron blackboard, an inner hole of a circle center disc is aligned with the circle center of a drawn circle, and when the circle center disc is adsorbed on the blackboard by a magnet, the colloid material generates enough static friction force to fix the positioning disc; then inserting a positioning pin into an inner hole of the central disc, pulling the pull rod to enable the scale at the junction of the pull rod and the positioning cylinder and the radius of the positioning cylinder to be equal to the radius of a circle to be drawn, screwing the positioning screw to position the pull rod, and lightly pressing the positioning cylinder with one hand and rotating the pull rod with the other hand to draw the circle; when the chalk clip is used for drawing and cutting line segments by a ruler and a compass, a circle center disc is not used, and the pull rod is pulled to ensure that the distance between the positioning foot and the chalk clip is equal to the length of the cut line segment; the whole compasses are simple and reliable in structure, the problem that the blackboard surface is pricked and damaged by the traditional compasses with iron points and the iron points slip is effectively solved, errors of the circle center and the radius do not exist in the rotation process of drawing circles, the drawing is accurate, and the operation is reliable.

Drawings

FIG. 1 is a schematic structural view of the present invention; in the figure, 1, a circle center disc, 2, an inner hole of the circle center disc, 3, a buckling concave position, 4, a positioning cylinder, 5, a positioning screw rod, 6, a positioning foot, 7, a pull rod, 8, a scale mark, 9, a chalk clamp and 10, a locking sleeve.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings 1 and the embodiments

According to the attached drawing 1, a circular magnet is taken as a main body of a circular center plate (1), an annular hole (2) of the circular center plate is in a circular truncated cone shape, the small bottom surface of the circular truncated cone-shaped annular hole is close to a blackboard, the diameter of the small bottom surface of the circular truncated cone-shaped annular hole is equal to 4 mm, the included angle between the generatrix of the circular truncated cone-shaped annular hole and the axis is 45 degrees, a buckling concave position (3) is reserved on the annular surface of the circular center plate close to the blackboard, a positioning cylinder (4) is in a cylindrical cylinder structure with the outer diameter of 4 cm, two pull rod holes are formed in the positioning cylinder (4), the two pull rod holes are horizontally symmetrical to the center line of the positioning cylinder (4), a pull rod (7) is matched with the two pull rod holes, and the pull rod (; the positioning cylinder (4) is also provided with a positioning screw hole and a positioning screw rod (5), and the positioning screw rod (5) is screwed to fix the position of the pull rod (7) relative to the positioning cylinder (4); the position of the junction between the positioning cylinder (4) and the pull rod (7) is marked with '+ 2', the radius of the drawn circle is obtained by adding 2 cm to the scale number of the junction, a truncated cone-shaped positioning pin (6) is arranged below the positioning cylinder (4), and the lower bottom surface of the truncated cone-shaped positioning pin (6) is replaced by a spherical crown inscribed in the truncated cone; one end of the pull rod (7) is provided with a chalk clamp seat which is cylindrical and concave, the inner diameter of the chalk clamp seat is equal to the outer diameter of the chalk clamp (9), and the chalk clamp (9) is fixedly embedded into the chalk clamp seat; and the upper surface of the pull rod (7) is provided with scale marks (8) for marking the length by taking the position corresponding to the center of the chalk holder as a starting point, and the unit length of the scale marks (8) is 1 cm.

Furthermore, the surface of the annular magnet of the central disc (1) close to the blackboard is attached with a colloid material for increasing friction, so that the static friction coefficient of the central disc and the blackboard surface is larger than 0.5.

Furthermore, the chalk clamp (9) is composed of a clamping sleeve and a tightening sleeve (10), the clamping sleeve is in a cylindrical shape with one open end and one closed end, the outer diameter of the closed end is equal to the inner diameter of the chalk clamp seat, the chalk clamp seat is embedded in the clamping sleeve, 3-6 axial gaps are arranged at the open end at equal intervals, the open end has an opening and closing function, and the clamping sleeve is sleeved with the locking sleeve (10).

Those not described in detail in this specification are within the skill of the art.

Claims

1. A compasses consists of a center disk, a positioning cylinder, a positioning foot, a pull rod, a positioning screw rod and a chalk clip; the blackboard is characterized in that the circular center plate takes a circular magnet as a main body, and a buckling concave position is reserved on the ring surface close to the blackboard; the circular center disc annular hole is in a circular table shape, the small bottom surface of the circular table-shaped annular hole is close to the blackboard, the diameter of the small bottom surface of the circular table-shaped annular hole is equal to the diameter of the lower end of the positioning pin, and the included angle between the generatrix of the circular table-shaped annular hole and the axis is 30-70 degrees, so that the circular table-shaped annular hole of the circular center disc not only meets the function of controlling the positioning pin not to slide, but also meets the circular table-shaped space required in the rotating process of the positioning pin; the positioning cylinder is of a cylindrical structure, two pull rod holes are formed in the positioning cylinder, the two pull rod holes are horizontally symmetrical to the center line of the positioning cylinder, the pull rods are matched with the pull rod holes, and the pull rods are inserted into the two pull rod holes in a seamless penetrating mode and pulled; the positioning cylinder is also provided with a positioning screw hole and a positioning screw rod; a positioning pin is arranged below the positioning cylinder; one end of the pull rod is provided with a chalk clamp seat which is cylindrical and concave, the inner diameter of the chalk clamp seat is equal to the outer diameter of the chalk clamp, and the chalk clamp is fixedly embedded into the chalk clamp seat; the chalk clamp is characterized in that a scale mark for marking the length is arranged on the upper surface of the pull rod by taking the position corresponding to the center of the chalk clamp seat as a starting point, a plus x mark is arranged on the side surface of the positioning cylinder towards the chalk clamp direction, wherein x is half of the outer diameter of the positioning cylinder, and the radius of a circle to be drawn is obtained by adding x to the number of scales at the joint of the pull rod and the positioning cylinder.

2. The compass of claim 1, wherein: the surface of the annular magnet of the central disc, which is close to the blackboard, is attached with a colloid material for increasing friction, so that the static friction coefficient of the central disc and the blackboard surface is larger than 0.5.

3. The compass of claim 1, wherein: the chalk clamp is composed of a clamping sleeve and a tightening sleeve, the clamping sleeve is in a cylindrical shape with one open end and one closed end, the outer diameter of the closed end is equal to the inner diameter of a chalk clamp seat, the chalk clamp seat is embedded in the clamping sleeve, 3-6 axial gaps are arranged at equal intervals at the open end, the open end has an opening and closing function, and the clamping sleeve is sleeved with a locking sleeve.