JPS5914000B2 - parabola plotter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel parabola drawing device that can easily draw a parabola when a principal axis, a focal point, and a point on the parabola are given.

When designing the shape of a lighting device that uses reflection, it is often necessary to draw a parabola given a principal axis, a focal point, and a point on the parabola.

In such cases, the conventional method is to calculate the coordinates of several points on the parabola to be drawn, and then connect the plotted points smoothly using a curved ruler, or as shown in Figure 1. As shown in , one end is fixed at a point Ta on the T ruler T, the other end is fixed at a given focal point F,
Using a thread U whose length is Ta110PF (where P is a given point on a parabola), while moving the T ruler T in a direction perpendicular to the main axis The conventional method was to draw a parabola by moving the pencil so that it was in contact with the ruler T and the thread U was kept under tension.

However, the former method is troublesome and takes a long time, and it is easy to make mistakes.The latter method is difficult to set the thread in a predetermined state, the thread easily comes off the pencil, and the accuracy of the drawn parabola is high. had bad drawbacks.

The present invention has been made for the purpose of eliminating the above-mentioned drawbacks of the prior art, and has been successfully achieved in providing a parabola drawing device that can quickly draw a parabola through simple operations and has an extremely simple structure. It is something.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below based on the drawings.

FIG. 2 is a diagram showing the arrangement of each device when drawing a parabola on a drawing paper using the device according to the present invention.

In the figure, reference numeral 10 denotes a conventional trafting machine, which has a straight edge 11 in the horizontal direction (lateral direction).
can be translated in the vertical direction (up and down).

Reference numeral 1 denotes a non-stretchable tape, one end of which is held by a first tape end holding device 20 fixed at the focal point of the parabola, and the other end a second tape end fixed to the tip of the straightedge 11. It is held by a holding device 30 and is hooked to a line drawing device 40 that moves along the straight edge 11 along the way.

A more detailed explanation will be given based on FIG. 3, which shows an enlarged view of the main parts of the above-mentioned apparatus.

The first tape end holding device 20 has a base plate 21 made of a transparent material, and a reel 22 is attached to the base plate 21 with a thumbscrew 23 as shown in FIG.

The reel 22 is attached to the thumbscrew 23 when the thumbscrew 23 is loosened.
The base plate 2 can be rotated around the base plate 2 in any rotational phase position by tightening the thumbscrew 23.
Fixed to 1.

The reel 22 has flange portions 2 at both ends as shown in FIG.
2a*22b, the flange portion 22a,
Tape 1 is wound between 22b.

The tape 1 is wound with its ends sandwiched between the slits 22c of the reel 22, and can be easily pulled out to a required length with the thumbscrew 23 loosened.

The base 21 also includes a guide cylinder 24 made of a transparent material.
is fixed.

The guide cylinder 24 has flange portions 24a at both upper and lower ends.

24b, and has a relatively small diameter leg portion 24c protruding from the lower surface, and this leg portion 24c is attached to the base plate 21.
The base plate 21 is fixed to the base plate 21 by being firmly fitted into a through hole formed in the base plate 21 .

The guide cylinder 24 is attached to the lower end surface of the leg portion 24c of the guide cylinder.
A hair cross line 24f is drawn that intersects on the center line of the second tape end holding device 30 (see FIG. 3).
has a fixing plate 31 fixed to the straightedge 11.

The lower surface of the fixing plate 31 has a dovetail groove 31a as shown in FIG.
is provided, and the fixing plate 31 is fitted with the trapezoidal cross-section mounting bracket 12 fixed to the end of the straight edge 11 to attach the straight edge 11 to the trafting machine 10 through this dovetail groove 31a. It is fixed by a set screw 32 and a nut 33.

The truncated conical head 32a of the set screw 32 fits into the dovetail groove 31.
It is accommodated in a tapered hole 3Ib formed in the fixing plate 31 so as to partially interfere with the fixing plate 31, and is engaged with the mounting fitting 12 by a notch 32b formed in the part thereof to prevent rotation. ing.

Therefore, when the nut 33 is tightened, the locking screw 3
2 is pulled upward, and the fixing plate 31 is fixed to the mounting bracket 12 by imitation of the head 32a.

Furthermore, the fixing plate 31 has a tapered hole 31c at its free end protruding from the straightedge 11, and has a slit-like notch 31d bored from the side end surface and communicating with the tapered hole 31c.

Therefore, as shown in FIG.
with the tapered hole 31 folded to form a loop.
c and the notch 31d, and then firmly fit the taper pin 34 into the tapered hole 31c.
a is sandwiched and fixed between the taper hole 31c and the taper pin 34.

The line drawing device 40 has a sliding plate 41 that slides along the edge 11a of the straightedge 11.

The sliding plate 41 has a linear edge portion 41a that slides on the edge 11a of the straightedge 11, and has a protrusion 41b with a circular cross section protruding at right angles to the plate surface approximately in the center as shown in FIG. have.

A drawing instrument insertion hole 41c is bored in the center of the projection 41b.

The drawing tool insertion hole 41c is a stepped hole, and when a drawing tool 55 such as a pen or pencil is inserted into the large diameter hole, the tip of the drawing tool 55 protrudes downward from the small diameter hole at the tip and the drawing paper is It is configured to come into contact with etc.

A guide roller 42 is rotatably fitted into the protrusion 41b, and is prevented from being pulled out by a nut 43 screwed into a male threaded portion 41d provided at the tip of the protrusion 41b.

The guide roller 42 is different from the guide cylinder 24 in that the diameter D2 of its body 42d is equal to the diameter D1 of the body 24d of the guide cylinder 24, and that it has flanges 42a and 42b at both ends. The same is true.

Further, the distance E1 between the body 42d of the guide roller 42 and the linear edge 41a of the sliding plate 41 is equal to the distance E2 between the slit-like notch 31d of the second tape edge holding device 30 and the edge 11a of the straightedge. It is configured to be.

Note that the sliding plate 41, guide roller 42, and nut 43 are preferably made of transparent material.

A method of drawing a parabola using the apparatus configured as described above will be explained based on FIGS. 2 and 3.

After locking the horizontal movement of the trafting machine 10 and setting the trafting machine 10 so that the straightedge 11 moves only in the direction perpendicular to the edge 11a, the main axis The drawing 50 is fixed so as to be parallel to the edge 11a.

The cross line 2 of the guide cylinder 24 is placed at a given focal point.
Align the intersection of 4f and attach the base plate 21 to the weight 51.
Fix it by etc.

Loosen the thumbscrew 23 and pull out the tape 1 from the reel 22.
After the guide cylinder 24 and the guide roller 421 are hooked up, the drawer end 1a is fixed to the fixing plate 31.

With the edge 41a of the sliding plate 41 in contact with the edge 11a of the straightedge 11, and with the small hole of the drawing tool insertion hole 41c of the sliding plate 41 positioned above a point on a given parabola, insert the tape. 1 is wound onto a reel 22, and when the tape 1 becomes tense, the thumb screw 23 is tightened to fix the reel 22.

With the above preparations complete, the only thing left to do is to insert a drawing tool 55 such as a pen or pencil into the drawing tool insertion hole 41c, and then move the straightedge 11 up and down using the trafting machine 10 while keeping the tape 1 in a tensioned state. By moving the drawing tool 55, the desired parabola is drawn.

The reason why the desired parabola is drawn by the above operation will be explained based on FIG. 7.

In FIG. 7, a circle centered on the focal point F indicates the body 24d of the guide cylinder, and a circle centered on a point P on the parabola indicates the body 42d of the guide roller.

R1 is the lowest point of the guide cylinder body 24d, and R1' is the point at which the tape 1 leaves the guide cylinder body 24d.

R2 is the point at which the tape 1 starts contacting the guide body 42dl, and R2' is the point at which the tape 1 separates.

Further, S indicates the fixed end of the tape 1, and g indicates a point descending from S by the radius r of the guide roller body in a direction perpendicular to the edge 11a of the straightedge.

Since the radius of the guide cylindrical body 24d and the radius of the guide roller 42d are made equal, the length R'1R2 of the straight portion of the tape 1 passed between them is always equal to the distance between their centers, that is, the radius of the guide roller 42d. It is equal to the distance FP between a given focal point F and a point P on the parabola.

Furthermore, since the tape 1 that is passed between the guide roller body 42d and the fixed plate 31 is parallel to the edge 11a of the straightedge, the length R2'S of the straight part of the tape 1 is always a line segment. Equal to PS'.

However, the total length of the tape 1 from point R1 to point S is always constant because the tape 1 does not expand or contract. Since the sum of the lengths is constant πr, the length L−πr of the straight portion of the tape 1 is also constant.

Therefore, the sum of the line segment FP and the line segment PS' is always constant, which means that the guide roller 42 can perform exactly the same movement as conventionally used to draw a parabola using a T-square and a thread. It shows what the drawing tool 55 attached to the center does.

This embodiment has been described in detail above.
, the means for fixing the fixed plate 31 to the straightedge 11, the means for regulating the relative position between the guide roller 42 and the straightedge 11, the means for positioning the line drawing tool, etc. However, the present invention is not limited to this embodiment, and various changes can be made in details.

For example, the guide roller 42 does not necessarily have to be rotatably mounted, but it is also possible to allow the tape 1 to slide on a fixed guide cylinder, or the sliding plate 41 can be eliminated, as shown in FIG. As shown in FIG. 3, it is also possible that the guide roller 42 itself contacts the straightedge through the flange portion 42b and rolls on the edge 11a thereof.

Also, the straight edge 11 is rj for the ruler of the rafting machine.
<It is also possible to use a T ruler.

It is also possible to change the tape 1 to thread, string, etc.

In summary, the parabola drawing device according to the present invention has a straightedge that moves in parallel on a plane on which a parabola is to be drawn in a direction perpendicular to its linear edge, and a body with a circular cross section, the center axis of which is perpendicular to the straight edge. Guide roller 4 that moves parallel to the edge of the ruler
A second guide body, a drawing tool such as a pencil that protrudes downward at the center axis position of the second guide body and contacts a plane on which a parabola is to be drawn, and a body portion having the same radius as the body portion of the first guide body. a second guide body such as a guide cylinder 24 having a cross line 24f, a second guide body holding plate such as a base plate 21 for holding the second guide body, a second guide body holding plate such as a base plate 21 for holding the second guide body, A reel rotatably attached to the guide body holding plate, a means such as a thumbscrew 23 capable of blocking the rotational movement of the reel at any rotational phase position, and a string-like body such as tape 1 wound around the reel; a fixing plate that is fixed to the straightedge and holds the drawn end of the string-like body apart from the edge of the straightedge by a distance equal to the distance between the edge of the straightedge and the body of the first guide body; 31
The invention is characterized in that it includes a draw-out end holder, and although it has a simple structure, it can draw a parabola quickly and accurately with extremely simple operations, and the design of equipment that utilizes parabolas; This has an excellent effect of improving drafting efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory diagram showing an example of a conventional parabola drawing method. FIG. 2 is an explanatory diagram showing the arrangement of each device in a drawing operation using an apparatus according to an embodiment of the present invention. FIG. 3 is a front view of main parts showing one embodiment of the present invention, and FIGS. 4, 5, and 6 are cross-sectional views of IV-IV, V-V, and Vl-Vl in FIG. 3, respectively. It is. FIG. 7 is an explanatory diagram showing the operating principle of the device shown in FIG. 3. FIG. 8 is a diagram corresponding to FIG. 6 in another embodiment of the present invention. 1: Tape (string-like body), 10 Nidrafting machine,
11: Straight ruler, 11a: Edge, 12: Mounting bracket, 20:
First tape end holding device, 21: Base plate, 22:
Reel, 23: thumbscrew, 24 guide cylinder, 24d body of guide cylinder, 30: second tape end holding device, 31:
Fixed plate, 32: Set screw, 33: Nut, 34: Taper pin, 40: Line drawing device, 41: Sliding plate, 41b: Projection,
41c: Wire drawing tool insertion hole 42 Ni guide roller, 42d body of Ni guide roller, 43: Nut, 55: Wire drawing tool. 201-

Claims (1)

[Scope of Claims] 1. A device that draws a parabola when a point on a parabola, a principal axis, and a focal point of the parabola are given, and moves the parabola in parallel on the plane on which the parabola is to be drawn in a direction perpendicular to its linear edge. a straightedge, a first guide body having a body with a circular cross section and whose center line moves parallel to the edge t of the straightedge, and a parabolic shape that projects downward at the center line position of the first guide body a drawing tool that touches the plane on which to draw;
a second guide body having a body having the same radius as the body of the first guide body; means for clearly indicating the center line position of the second guide body; a second guide body holding plate that holds the second guide body; A reel rotatably attached to the second guide body holding plate, a means capable of blocking the rotational movement of the reel at an arbitrary rotational phase position, and a string-like body wound around the reel; a drawer end holder fixed to the arrangement ruler and holding the drawer end of the string-like body separated from the edge of the straight ruler by a distance equal to the distance between the edge of the straight ruler and the body of the first guide body; A parabola plotting device characterized by comprising: