CN2290834Y - Protractor - Google Patents

Abstract

The utility model relates to a protractor which is composed of a pin shaft which is connected with two straight rules which are provided with the same size and shape and are provided with graduation marks. The straight rules can be rotated around the pin shaft under the external force, and a clamping jaw is respectively formed at both ends of the pin shaft. The angle of a flat object or a three-dimensional space object can be conveniently measured, and the protractor is not limited by the shape of the object. Simultaneously, the utility model has the advantages of small size, simple structure, convenient operation, etc. The protractor is an ideal measuring instrument.

Description

A kind of protractor

The utility model relates to a kind of protractor.

Protractor of the prior art mainly is made of a semicircular bodies, and is evenly distributed with the scale mark of angle at the semicircular bodies periphery.When surveying the object angle, earlier the semicircular body horizontal edge is alignd with a limit of object, according to the indication of the scale on the another side place semicircular body peripheral position of object, the angle that can read this object.Though this kind angle gage structure is simple, use its limitation, because its angle of Measuring Object in the plane, and be only limited to the angle of regular object on the plane.And to the object on the space, promptly two of testee limits just are difficult for accurately measuring its angle not at grade, and are especially powerless especially to the irregularly shaped object in the space.In addition, this kind protractor can not directly be delineated out with this angle after measuring angle, could draw out and will use as the instrument of ruler class.

Task of the present utility model provides a kind of protractor, and it can be measured space object easily, especially measure the angle of space irregularly shaped object, and can disposable the angle of measuring be drawn out.

For finishing above-mentioned task, the solution that the utility model adopts is: two sizes that it is connected by bearing pin, shape is identical and the ruler that has a scale mark is formed, described ruler can rotate around bearing pin under external force, and forms jaw respectively at the two ends of bearing pin.

Following relational expression is satisfied in the distribution of above-mentioned ruler high scale: $\mathrm{\α}=2\mathrm{arctg}\frac{d}{2L}$

Wherein: α be two rulers when opening inner side edge along formed angle;

D is the transverse width of ruler;

L is two rulers when opening the α angle, and inboard joining B of ruler and bearing pin draw the distance between the intersection point A of vertical line to the ruler inner side edge.

Two above-mentioned rulers are rotatable under external force 0-360 degree in same plane.

Because the angle that the utility model adopts structure that two rulers sway to come measurement plane object or three dimensions object, so it is not subjected to the restriction of body form, range of application is very extensive.Simultaneously it also to have a volume little, simple in structure, easy to use, advantages such as accurate measurement are a kind of desirable measuring appliances.

Below in conjunction with drawings and Examples the utility model is further described.

Accompanying drawing 1 is the utility model visual texture synoptic diagram

Accompanying drawing 1 has provided appearance structure of the present utility model, and it comprises two rulers 1 and a bearing pin 2.The size and the shape of two rulers 1 equate that all bearing pin 2 links together them at the position, a termination of approaching ruler 1.This kind connection is the connection on the symmetric points of two rulers 1, and periphery was on same straight line when promptly two rulers 1 were closed.Two rulers 1 can rotate around bearing pin 2 under external force, and can be arbitrarily angled in the rotation between the 0-360 degree.Bearing pin 2 can be made by the nuts and bolt structure, adjusts elasticity between two rulers so easily.All have scale mark 3 on two rulers 1, this scale mark is not equidistant arrangement, is engraved on the ruler 1 but calculate numeric indicia in following relational expression.Its relational expression is as follows: establishing two rulers, 1 opening angle is α, and the horizontal directive tendency of ruler is d, and bearing pin 2 is vertical profile line in ruler 1, with ruler 1 inboard intersection point be A, two rulers, 1 inner side edge is B, then AB=L along joining.Relational expression according to trigonometric function:

For: $\mathrm{tg}\left(\frac{1}{2}\mathrm{\α}\right)=\frac{\frac{1}{2}d}{L}$

Then $\mathrm{\α}=\mathrm{arctg}\frac{d}{2L}$

Be α=f (L) or L=f (α)

α and L have funtcional relationship one to one as can be seen from above-mentioned formula, can calibrate scale mark on the ruler 1 according to following formula.

During use, earlier two rulers 1 are separately formed the jaw shape around bearing pin 2.Be the inboard periphery through testee of two ruler iron with jaw then, and the inner side edge edge of two rulers 1 is pasted mutually with testee, take off protractor this moment, and then two rulers, 1 inner side edge is the angle of testee along the pairing scale mark of joining.When measuring the obtuse angle, this obtuse angle is aimed in the outside of the inboard of an available ruler 1 and another ruler 1, then reads the number of complementary angle as stated above earlier, spends the formula that subtracts complementary angle with 180 again and obtains this obtuse angle.In addition, with can draw arbitrarily angled on the plane of this protractor.

Claims (3)

1, a kind of protractor is characterized in that: two sizes that its bearing pin connects, and the identical and ruler that have a scale mark of shape is formed, and described ruler can rotate around bearing pin under external force, and forms jaw respectively at the two ends of bearing pin.

2, according to the protractor described in the claim 1, it is characterized in that: following relational expression is satisfied in the distribution of described ruler high scale: $\mathrm{\α}=2\mathrm{arctg}\frac{d}{2L}$

Wherein: α be two rulers when opening inner side edge along formed angle;

D is the transverse width of ruler;

L is two rulers when opening the α angle, and inboard joining B of ruler and bearing pin are in ruler

Side draws the distance between the intersection point A of vertical line.

3, according to the protractor described in the claim 1, it is characterized in that: two rulers are rotatable under external force 0-360 degree in same plane.

Images