SU75507A1 - A device for drawing arcs of circles of large radii - Google Patents

Description

Instruments for drawing arcs of circles of large radii are known, having a flexible ruler and a mechanism graduated with radii of curvature, which communicate to both ends of the ruler the necessary equal angles with the line connecting the ends of the ruler.

The proposed device differs from the existing ones in that the mechanism for the ruler curvature is made in the form of a double, series-connected hinge parallelogram, equipped with a limb at the end for measuring the angle between the direction of the ruler ends and the line connecting these ends, and graduated in curvature radii.

FIG. 1 shows a top view of the device with a finite radius of the arc; in fig. 2 - top view of the device at an infinite arc radius; in fig. 3 is a side view of the device.

The device consists of the actual line and the installation mechanism. The role of the mechanism consisting of two hinged parallelograms 1 and 2 consists in transmitting to the ends of a ruler 3 equal (in absolute value) bending moments, and consequently, to the radius of the circle along which the ruler bends, is achieved by rotating the right end of the ruler relative to 4 (Fig .). The turn is made by the handle 5 with the clamping device 6, which allows to fix the handle on the limb.

The left end of the ruler is connected to the limb by a hinged mechanism, which allows free end displacement relative to the limb, but excluding the possibility of their relative rotation.

Special holders are attached to the ruler, with which it is pressed by the fingers to the drawing while drawing the arc. If it is necessary to fix the mechanism to ensure the invariance of the distance between the ends of the ruler, a screw clamping device can be installed on one of the intermediate hinges 7 and 5 of the mechanism, in which three rods converge. By clamping this joint (after setting the pointer to the desired position), the mechanism is turned into a fixed system.

To ensure the correct circular shape, the bend of the ruler is very

move freely relative to the limbus. Therefore, the design of the hinges of the mechanism should be such that the friction in them is minimal. In order to reduce the influence of friction in the mechanism on the shape of the bend of the ruler, its rigidity should be as large as possible.

Subject invention

A device for drawing arcs of circles of large radii with an elastic ruler and a mechanism graduated within radii of curvature, telling both ends of the ruler the necessary equal angles with the line connecting the ends of the ruler, characterized in that the mechanism is designed as a double-connected articulated parallelogram fitted at the end a limb for measuring the above angle and graded in radii of curvature.

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