CN2257601Y - Quick protractor - Google Patents

Abstract

The utility model relates to a protractor which can be used for quickly and accurately measuring angles. The position of the center of a circle of the existing protractor is additionally provided with a rotary supporting arm to make the center of a circle on one side of the supporting arm. The supporting arm is rotated for directly indicating the accurate degree of an angle to be measured.

Description

Quick protractor

The utility model relates to a kind of angle measurer of the size that takes measurement of an angle, the protractor of the size that especially can take measurement of an angle rapidly and accurately.

At present, known protractor is a semicircular surface plate, and the diameter of semicircle is a bottom line, and the mid point of diameter is the center of circle, and semi-circular arc is marked with 180 ° angle index.When the number of degrees of measured angular, the summit at angle is overlapped with the center of circle, a limit at angle is overlapped with bottom line, corresponding numeral is the number of degrees of institute's angle measurement on the indicated circular arc in another limit.But, when the length of the tested arm of angle during, just need the general size of estimating angle less than the protractor arc radius, make accuracy too poor; Perhaps the limit that prolongs institute's angulation by an other ruler is intersected the circular arc of it and protractor, measuring the number of degrees at angle exactly, but this using method is a complexity carry on a shoulder pole again mistake between; When we will mark an angle, can only be after marking a limit, the throughput hornwork is determined a point on another limit, connects this point and center of circle with ruler then, marks another limit at angle, this equally also is that complexity is time-consuming again.

The purpose of this utility model provides a kind of protractor, and it not only can measure the number of degrees at angle quickly and accurately, can also directly mark desired angle fast.

The purpose of this utility model is achieved in that at the circle centre position of protractor installs an axle that freely rotates, fixing on the axle on the support arm, make the center of circle on a limit of support arm, on support arm, begin outwards to mark length number by the center of circle, simultaneously also begin to mark length number to both sides by the center of circle on the base, when the number of degrees of measured angular, the base of protractor is overlapped with a limit at angle, the center of circle overlaps with the summit at angle, rotating support arm, make it to overlap with another limit at angle, then the indicated number of degrees of support arm are the number of degrees at angle; When drawing an angle, successively on the base of protractor, the draw limit at angle, make the summit at angle overlap ' one limit with the center of circle and overlap with the base of protractor, at this moment rotating support arm is pointed on the angle that will draw support arm, gets final product along draw another limit at angle of support arm then.

Owing to adopt such scheme, the number of degrees of measured angular or the angle of drawing quickly and accurately, and this protractor compared with former protractor, only increased a support arm, and simple in structure.

Below in conjunction with accompanying drawing the utility model is further specified.

Fig. 1 is a synoptic diagram of the present utility model.

Among the figure: 1, protractor plate face 2, protractor base 3, rotation axis

4, limit 6, the angle index of support arm 5, use when measuring

Among the figure: in protractor plate face＜1〉semicircle subscript upper angle scale＜6; On the base＜2 locate to put on length number; Rotary support arm＜4 are being installed on the position of center of circle O〉be fixed on rotation axis＜3〉on, make rotation axis＜3〉central point in support arm＜4 measuring limit＜5 on, in measuring this edge＜5〉go up to light and outwards mark length number successively from O.During measurement, only need measuring limit＜5 and base＜2 overlap with two limits of measured angle and can directly read the angle number.

Claims (1)

1, a kind of quick protractor, its plate face is marked with garden heart O, radian number＜6 〉, it is characterized in that: connect rotating support arm＜4 at garden heart place, make the garden heart in support arm＜4〉limit＜5 on.

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