FR2556655A1 - Device for drawing an involute of a circle - Google Patents

Abstract

Device for producing an involute of a circle. The invention relates to a device capable of drawing an involute of a circle quickly and sufficiently accurately for ordinary use. It consists of a cylinder A of axis I around which a flexible strip F fixed to the cylinder A is wound or unwound. When unwound with a slight pulling action, the point J of the strip F describes a curve D known as the involute of the circle. The device according to the invention is particularly intended for surveyors, draughtsmen, students, sheet metal workers and mechanical engineers.

Description

 The present invention relates to instruments used by designers of all kinds, surveyors, sheet metal workers, adjusters, verifiers, mechanics, students or gardeners such as compass boxes, angle finders, plotting devices various, useful for drawing, sketching, machining, cutting, reading or graphic calculation.

 In the current state of the art, this tracing is done by points, by corrections had by arcs of a circle locally approaching the curve called involute of a circle.

The device according to the invention makes it possible, theoretically, to obtain a curve called an involute of a circle with a precision which is entirely acceptable and compatible with the demand or the need for graphic art in the usual cases.

 The circle developer can be traced with a single gesture over all or part of its length and thus does not have questionable connections or repeats with breaks. All points on the curve are found in their exact locations.

de toute ou partie de la développante de cercleYpour tous les usages di rectos ou indirects, tels que l'étude ou l'usinage des engrenages ainsi que le calcul graphique d'une développante entiere ou partielle. Pour se faire, Si le diamètre à développer n'est pas égal à celui de l'outil realisé, le dessin peut etre exécuté à une échelle de raccordement.The object of the invention is the tracing, cutting, verification

of all or part of the involute of circle Y for all direct or indirect uses, such as the study or machining of gears as well as the graphic calculation of an entire involute or partial. To do so, if the diameter to be developed is not equal to that of the tool produced, the drawing can be executed on a connecting scale.

 The invention provides a number of different diameters and judiciously chosen to make optimum use of the possibilities offered in the scale of sizes, in order to reduce the material required.

 The device which is the subject of the invention is based on the association of a fixed (C) or adjustable (extendable or retractable) circle on which a material (F), whatever its nature or composition, is wound, non-stretchable under weak pulls, of negligible thickness.

This material is fixed at one of its ends (A) on the circle and has at its other movable end (J) a tracer, verifier, reliever or machinist object.

 The previous description is already known and is sometimes used to explain the curve in question. The originality of the principle stated in the present invention consists in creating a practical instrument having a center materialized on both sides (I) (point or axis) so that it can be used concretely as if it were a "compass "describing a curve instead of a circumference. Thus, several curves or parts of curves can be drawn or described from the rotation of the assembly; curves of opposite direction are possible after turning over of the whole of the described instrument.

 The device of the present invention allows the involute of the circle to pass through the movable point (J) of the end of the material while keeping the cylinder (H) fixed and simultaneously unrolling the flexible part (F) while imparting to it a sufficient traction so that the developed part is permanently straight and tangent to the cylinder, like a straight line which rolls without sliding on a fixed circumference (very definition of the involute of the circle).

- un cylindre support (H) muni d'un axe (I) permettant de centrer la
pièce (H) soit sur une de ses faces, soit sur l'autre, - une lame souple fixée à un bout sur une génératrice du cylindre (A), - un outil quelconque fixé à l'extrémité mobile (J) de la lame sou
ple (F).The device consists of Dar:

- a support cylinder (H) provided with an axis (I) allowing to center the
part (H) either on one of its faces, or on the other, - a flexible blade fixed at one end to a generator of the cylinder (A), - any tool fixed to the movable end (J) of the blade penny
ple (F).

The flexible blade can be replaced by a nylon, steel, resistant wire or other cable, depending on the nature of the work required and the diameter considered.

 Application of the device to the manufacture of a template (G) of an involute of a circle which, also having a materialized axis (I), can be used for the same purpose: the pencil of the designer or the tool of the worker n ' having only to follow the contour (D).

Claims (8)

1 - Device to obtain a template reproducing the route  of a curve called involute of a circle, characterized in that it  consists of a flat cylinder (H) of medium thickness (E) fitted  an axis with its two faces (I), of determined diameter, on which  comes to wind a flexible blade (F) (not extensible) fixed to a  tip on a generator (A); at the other movable end of the blade  being attached a tool (J), generally a drawing point, mechanical pencil  or ink tracing equipment. 2 - Device according to claim 1, characterized in that the tool  can also be a cutting, cutting, welding, machining or  measuring; the tools can be conventional or more efficient,  such as optical solutions or lasers. 3 - Template obtained with the device of claims 1 and 2, charac-  terized by a plate (G) cut or simply traced according to the dice  veloppante of circle (D) of the base circumference (C) having an axis  materialized (I) on each side. 4 - Template according to claim 3, characterized in that it can be  made of opaque or transparent materials, wholly or by  tial. 5 - Template according to claims 3 and 4, characterized in that the cir  basic conference (C) can have several dimensions and that these  dimensions can be superimposed or not. 6 - Template according to claims 3, 4 and 5, characterized in that it can  be graduated on all its parts. 7 - Template according to claims 3, 4, 5 and 6, characterized in that it  can be used with other systems, for enlargements or  decreases for example. 8 - Template according to claims 3, 4, 5, 6 and 7, characterized in that  that it can be used by electronic tracking systems on  screens or the like, assisted or not by computer.