JPH0780390B2 - Oval drafter - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an ellipse drafter that draws an ellipse.

[Conventional technology]

FIG. 11 shows what is called a Swadi ellipse drafting machine. The spur gear 4 has twice as many teeth as the spur gear 5, and the spur gear 4,
Reference numeral 5 meshes with the intermediate spur gear 2. The angles of the arms 1 and 3 are variable, and thus the distance between the spur gears 4 and 5 can be changed. The angles of the arms 1 and 3 are fixed after setting the distance between the spur gears 4 and 5 to a desired value. The arm 7 of the drawing means 8 rotates together with the spur gear 5 and can be freely inserted and removed.
Secure with screws not shown. Arm 1 with spur gear 4 stationary
When is rotated once, the drawing means 8 draws an ellipse (at this time, the gear 5 and the arm 7 rotate twice).

FIG. 12 is a special case of the Swadi ellipse drafting machine. 9, 10 and 13 are bevel gears, respectively, and 14
Is a bevel gear with half the number. The bevel gears 10 and 13 rotate together with a horizontal shaft 19, and the bevel gear 9 is fixed to a support base 18 and is stationary. The vertical axis 15 rotates with the bevel gear 14. Supports 18 with the frames 11 and 12 centered on the shaft of the bevel gear 9
When it is rotated once around, the tip of the drawing means 17 draws an ellipse having a major radius (a + b) and a minor radius (ab). here,
a is the distance between the bevel gear 9 and the vertical axis 15, b is the distance between the vertical axis 15 and the tip of the drawing means, and the magnitudes of these distances a and b can be arbitrarily changed.

[Problems to be Solved by the Invention]

The conventional ellipse drafter cannot draw an ellipse unless both the major axis and the minor axis are known, and the ellipse can be drawn only by knowing the angle and the major axis (or the minor axis). There wasn't.

The present invention has been made in view of such circumstances, and it is possible to draw an ellipse only by giving an angle and a major axis (or a minor axis), and it is possible to draw ellipses of different sizes at the same angle. An object is to provide an easy ellipse drafting machine.

[Means for Solving the Problems]

The ellipse drafting machine according to the present invention comprises a center member rotated about the center of an ellipse to be drawn, and a first beam supported by the center member in a direction parallel to the plane of the paper on which the ellipse is drawn. A second beam support which is supported by the first beam and is movable in the length direction of the first beam; and a second beam support which rotates in a plane parallel to the paper surface. Possible second beam extending in a direction parallel to the plane of the paper, drawing means supported by the second beam, linking the first beam and the second beam, When the first beam is rotated together with the central member,
A transmission unit that rotates the second beam twice while the first beam rotates once; and a predetermined ratio with respect to the amount of movement when the second beam support is moved in the length direction of the first beam. And a means for moving the drawing means in the lengthwise direction of the second beam by a movement amount that forms the predetermined ratio, and the predetermined ratio is variable.

[Action]

When drawing an ellipse with this ellipse drafting machine, the first beam is rotated together with the central member about the center of the ellipse to be drawn. Then, the second beam makes two revolutions while the central member and the first beam make one revolution, so that the drawing means draws an ellipse on the paper surface according to the same principle as the conventional ellipse drafting machine.

Here, the distance between the central agent and the center of rotation of the first beam and the center of rotation of the second beam is a, the distance between the center of rotation of the second beam and the drawing means is b, and the major axis of the ellipse to be drawn is If R is R, the minor radius is r, and the angle is α, then R = (a + b) (1) r = (ab) (2) sin α = (ab) / (a + b) (3).

Next, in this ellipse drafter, angle α and major radius R
The procedure for drawing an ellipse when given is explained.

The distance a is changed by moving the second beam support in the lengthwise direction of the first beam, and the distance b is changed by moving the drawing means in the lengthwise direction of the second beam. When the two-beam support is moved in the lengthwise direction of the first beam, the drawing means is moved in the lengthwise direction of the second beam by an amount of movement that forms a predetermined ratio with respect to the amount of movement. From the relationship of equation (3), when the predetermined ratio is held constant, the value of the angle α of the ellipse becomes constant even if a and b change. That is, when the predetermined ratio is kept constant, the value of the ellipse angle α does not change even if the distances a and b are changed by moving the second beam support and the drawing means.

Therefore, after first maintaining the predetermined ratio at a value corresponding to the given angle α, the second beam support is moved in the length direction of the first beam to set the distance (a + b) to the given major radius R. If combined, an ellipse with a given angle α and major radius R can be drawn by the drawing means.

Similarly, when drawing an ellipse based on the angle α and the short radius r, the second beam support is held in the longitudinal direction of the first beam after the predetermined ratio is held at a value corresponding to the angle α. It is sufficient to move and match the distance (ab) with the given major radius R.

〔Example〕

 Hereinafter, the present invention will be described based on embodiments shown in the drawings.

1 to 10 show an embodiment of the present invention. In this embodiment, a fixed plate 2 is fixed to the lower end of the fixed arm 1, and the fixed arm 1 is fixed to the scale support portion of a drafter (not shown) via the fixed plate 2. . A center support member 3 is fixed to the upper end of the fixed arm 1, and the center support member 3 is integrally provided with a boss portion 3a. On the inner peripheral surface of the boss portion 3a, as shown in FIG. 3, a cylindrical portion integrally provided with the bonding material 4 is formed.
The outer peripheral surface of 4a is rotatably fitted. The cylindrical portion 4a
A central hole provided in a disc-shaped major axis angle scale plate 5 is fitted on the outer peripheral surface near the upper end of the shaft portion 6a of the central knob 6 on the inner peripheral surface of the cylindrical portion 4a. It is fitted. The center knob 6, the coupling material 4, and the long-axis angle scale plate 5 are fixed to each other by being fastened to the lock nuts 7 and 8 so that they rotate integrally. A central arm 9 is fixed to the lower end of the binding member 4, and a central needle 11 is attached to the lower end of the central arm 9 via a needle support member 10. The needle support member 10 is adjustable in position with respect to the central arm 9 so that the position of the central needle 11 can be aligned with the axis of the central knob 6. When drawing an ellipse, the position of the central needle 11 is adjusted. Center knob 6
Align with the axis of.

As shown in FIG. 2, an angle scale 5a is provided on the upper surface of the major axis angle scale plate 5. As best shown in FIG. 4, a slit 3b is provided near the upper portion of the boss portion 3a of the center support member 3, and the slit 3b of the center support member 3 is directed to one side of the portion. The non-threaded portion 12a of the shaft portion of the lock knob 12 is penetrated, and the male screw portion 12b provided at the tip of the shaft portion of the direction lock knob 12 is screwed into the other. Thereby, the central knob 6, the coupling member 4, the long-axis angle scale plate 5, and the central arm 9 can rotate with respect to the central support member 3 when the central lock knob 12 is not tightened, but when the direction lock knob 12 is tightened. The binding member 4 is locked.

One end of a first beam 13 is fixed near the upper end of the central arm 9, and the first beam 13 is perpendicular to the axis of the central knob 6 (parallel to the paper surface 14 on which an ellipse is to be drawn). Direction). Further, as shown in FIG. 1, the first beam 13 is provided with a scale 13a. Reference numeral 15 is a second beam support, and this second beam support 15 is provided with a dovetail-shaped beam fitting groove 15a as shown in FIG. The first beam 13 has a dovetail cross-sectional shape corresponding to the beam fitting groove 15a, and the second beam support 15 is fitted to the first beam 13 in the beam fitting groove 15a. As a result, the second beam support 15 is supported by the first beam 13 so as to be slidable along the length direction of the first beam 13.

A shaft support portion 15b is provided under the second beam support body 15, and the first shift pulley 1 is attached to the shaft support portion 15b.
A shaft portion 16a provided integrally with 6 is rotatably fitted. A first synchromesh rope 17 is wound around the first shift pulley 16 once. Then, the first synchromesh rope 17 has the first beam 13 at both ends thereof.
And is stretched in the length direction of the first beam 13. As a result, when the first shift pulley 16 is rotated, the pulley of the first synchromesh rope 17 is
By shifting the part wound around 16
16 and thus the second beam support 15 slides along the first beam 13.

As shown in FIG. 7, the screw 20 is provided with screw portions 20a and 20b at two locations, a tip portion and a head side portion, and there is no thread between these screw portions 20a and 20b. A screw portion 20c is provided. The threaded portion 20a at the tip portion is the second beam support 1
5 is screwed in, and the wedge 21 has a screw 20 on the non-screw part 20c.
Is movably fitted in the axial direction. The slope of the wedge 21 faces the lower surface of the first beam 13.
A first shift lock knob 22 is screwed into the screw portion 20b on the head side of the screw 20, and the tip of the lock knob 22 is brought into contact with the rear end of the wedge 21.

As shown in FIG. 5, the second beam support 15
A female screw is formed in a direction parallel to the central knob 6 on the shaft supporting portion 15c provided on the upper part of the shaft coaxially with the shaft supporting portion 15b,
A male screw portion 23a provided on a part of the outer circumference of the upper shaft 23 is screwed into the female screw. The lower end side of the upper shaft 23 is fitted to the inner circumference of the shaft portion 16a of the first shift pulley 16 so as to be rotatable with respect to the shaft portion 16a. A disc-shaped retaining plate 24 is attached to the lower end of the upper shaft 23, and the retaining plate 24 faces the lower end of the shaft portion 16a. An upper interrupting lever 19 is fixed to the upper end of the upper shaft 23, and when the lever 19 is rotated, the upper shaft 23 is moved to the first position by screwing the female screw of the shaft supporting portion 15b and the male screw portion 23a. It moves up and down with respect to the two-beam support 15.

A case 25 is fixed to the lower end of the second beam support 15. At the lower end of the shaft portion 16a of the first shift pulley 16, a first disc 26 is fixed coaxially with the pulley 16. Most of the first circular plate 26 is housed inside the case 25, but a part of the outer periphery of the first circular plate 26 projects outside the front and rear of the case 25. Further, on the outer peripheral portion of the lower surface of the first circular plate 26, an annular concave portion 26a which is recessed from other portions of the lower surface.
Is provided.

As shown in FIG. 1 and FIG.
A rack 27 is supported by 25 so as to be movable in a direction parallel to the first beam 13. As shown in FIG. 8, the case 25 is provided with a boss portion 25a. A pinion 28 is rotatably supported by the boss portion 25a, and the pinion 28 is engaged with the rack 27 inside the case 25. The end of the pinion 28 opposite to the rack 27 projects outside the case 25, and the end forms an elliptical angle setting knob 28a. The case 25 has a boss portion 25b.
The male screw portion 29a provided on the elliptical angle lock knob 29 is screwed into the boss portion 25b, and the tip of the male screw portion 29a faces the rack 27.

As shown in FIGS. 5, 8 and 9, a friction axle 30 extending parallel to the rack 27 and extending in the radial direction of the first disc 26 is rotatably supported on the case 25. Most of the friction axle 30 has a non-circular cross section (see FIG. 5). Further, the first friction wheel 31 cannot rotate with respect to the friction axle 30 and the friction axle 30 cannot rotate.
The first friction wheel 31 is supported so as to be movable in the axial direction of 30, and an annular groove 31a is provided in the boss portion of the first friction wheel 31. Further, in the friction axle 30, the second friction wheel 32 cannot rotate with respect to the friction axle 30 and cannot move in the axial direction of the friction axle 30 below the annular recess 26a of the first disk 26. Supported by. A fork 33 is fixed to the rack 27, and a forked portion of the fork 33 has a groove 31 of the first friction wheel 31.
is fitted to a. The fork 33 has an angle indicating projection 3
3a is provided, and the angle indicating protrusion 33a is provided on the case 25.
It slightly projects to the outside from an elongated hole 25c (see FIG. 1) provided in the horizontal direction. The case 25 is provided with elliptic angle scales 340 on both sides of the elongated hole 25c.

As shown in FIG. 3, the upper shaft 23 has a collar portion.
23b is provided, and a thrust bearing 35 and a first spring 36 are interposed between the flange portion 23b and the first shift pulley 16, and the spring 36 causes the first disc 26 to have a first friction. Car 31
It is urged to press. Since the annular recess 26a is provided on the outer peripheral portion of the first disc 26, the second friction wheel 3
2 does not always contact the first disc 26.

At the lower end of the case 25, a male screw portion 37a provided near the upper end of the outer circumference of the sleeve 37 is screwed coaxially with the upper shaft 23. A lower connecting lever 38 is fixed to the sleeve 37, and when the lever 38 is rotated, the sleeve 37 moves up and down with respect to the case 25. At the lower end of the sleeve 37, a swiveling pulley 39 having teeth on its outer peripheral surface is rotatably supported with respect to the sleeve 37. The pulley
A pulley holder 40 is fixed to the lower end of 39.
A lower shaft 41 is rotatably fitted to the inner peripheral surface of the sleeve 37. The upper end of the lower shaft 41 penetrates into the case 25, and the lower end penetrates the pulley to extend into the holder. There is. Here, the lower shaft 41 is also rotatable with respect to the pulley 39 and the pulley holder 40.

A collar portion 41a is provided near the upper end of the lower shaft 41, and a second disc 42 is fixed to the upper surface side of the collar portion 41a. Most of the second disc 42 is housed in the case 25, but a part of the outer periphery of the second disc 42 is projected to the outside in the front and rear of the case 25. Further, on the outer peripheral portion of the upper surface of the second circular plate 42, an annular convex portion projecting from other portions of the upper surface.
42a is provided. The lower surface of the brim portion 41a and the pulley
A thrust bearing 43 and a second spring 44 are interposed between the spring 39 and 39, and the spring 44 urges the second disc 42 to press the annular convex portion 42a of the second friction wheel 32. There is. The first friction wheel 31 is restricted in its moving range on the friction wheel shaft 30 so as not to always contact the second disc 42.

A second shift pulley 45 is fixed to the lower end of the lower shaft 41 in the pulley holder 40. As shown in FIG. 5, a dovetail-shaped beam fitting groove 40a is provided in the lower portion of the pulley holder 40 in a direction perpendicular to the central knob 6. In the beam fitting groove 40a, a second beam 46 having a dovetail cross-sectional shape corresponding to the groove is supported slidably in the direction vertical to the central knob 6. As shown in FIG. 1, a second synchromesh rope 47 is wound around the second shift pulley 45 once, and both ends of the synchromesh rope 47 are fixed to the second beam 46. And is stretched in the length direction of the second beam 46. As a result, when the second shift pulley 45 is rotated, the portion of the synchromesh rope 47 wound around the pulley 45 shifts, and the second beam 46 moves in the direction perpendicular to the central knob 6. The second beam 46 is provided with a scale 46a. A pencil assembly 48 is attached to one end of the second beam 46 as a drawing means in a direction parallel to the center knob 6. The pencil assembly 48 allows the pencil lead to be taken in and out. In the present invention, it goes without saying that other kinds of drawing means such as a drawing pen using ink can be used as the drawing means.

As shown in FIGS. 5 and 10, the bolt 20
Similarly to the bolt 49, the bolt 49 is provided with screw portions 49a and 49b at two locations, a tip portion and a head side portion.
A non-screw portion 49c is provided between 9a and 49b. The threaded portion 49a at the tip is screwed to the pulley holder 40. A wedge 50 is fitted to the non-screw portion 49c so as to be movable in the axial direction of the bolt 49, and an inclined surface of the wedge 50 faces the lower surface of the second beam 46. A second shift lock knob 51 is screwed into a screw portion 49b on the head side of the bolt 49, and the tip of the knob 51 is brought into contact with the rear end of the wedge 50.

As shown in FIG. 10, the pulley holder 40 is provided with a hole 40b in contact with the lower shaft 41 in a direction perpendicular to the lower shaft 41, and two lock pieces 52 are provided in the hole 40b. ,
53 are inserted and these locking pieces sandwich the lower shaft 41 between them. A non-screw portion of a shaft portion 54a integrally provided with the lock knob 54 is passed through the lock piece 53, and a screw portion provided at a tip portion of the shaft portion 54a is fitted into the lock piece 52. Therefore, when the lock knob 54 is tightened, the lock pieces 52 and 53 hold the lower shaft 41, and the lower shaft 41 is locked to the pulley holder 40.

As shown in FIGS. 1 and 3, an upper end portion of a sleeve 57 is fixed to the center support member 3 via connecting plates 55 and 56. As shown in FIGS. 1 and 5, a coupling plate 59 is fixed to a lower end portion of the sleeve 57 via a coupling plate 58, and the coupling plate 59 is used for the sleeve 37.
Is rotatably connected to the sleeve 37. The sleeve 57 extends in a direction parallel to the central knob 6, and an intermediate shaft 60 is rotatably fitted to the inner peripheral surface of the sleeve 57. An intermediate pulley 61 having teeth on the outer circumference is fixed to the upper end of the intermediate shaft 60, and an intermediate pulley 62 having teeth on the outer circumference is fixed to the lower end of the intermediate shaft 60. .

As shown in FIGS. 1 and 3, a central pulley 63 having teeth on its outer periphery is fixed to the boss portion 3a of the central support member 3. Here, the intermediate pulley 61,6
2 and swivel pulley 39 have the same number of teeth, center pulley 6
The number of teeth of 3 is twice that of the pulleys 39, 61 and 62. A timing belt 64 is wound around the center pulley 63 and the intermediate pulley 61,
A timing belt 65 is wound around 62 and the turning pulley 39.

Next, the usage of this ellipse drafting machine will be described.

First, the fixing plate 2 is attached to the scale support portion of the drafter, and the scale support portion is fixed at a predetermined position with respect to the paper surface 14, whereby the fixing arm 1 is fixed at an appropriate position and direction.

When the central knob 6 is pinched with a finger and rotated in this state, the central arm 9 and the first beam 13 rotate integrally with the central knob 6. Then, since the central pulley 63 is fixed to the fixed arm 1 and then to the paper surface 14, the intermediate pulley 61 around which the timing belt 64 is wound is rotated between the central pulley 63 and the intermediate pulley 61, and thus the intermediate shaft.
The intermediate pulley 60 and the intermediate pulley 62 rotate, and further, the rotary pulley 39 and the pulley holder 40 and the second beam 46 around which the timing belt 65 is wound between the intermediate pulley 62 and the intermediate pulley 62 rotate. Since the number of teeth of the central pulley 63 is twice the number of teeth of the swiveling pulley 39, while the central arm 9 and the first beam 13 make one revolution, the second beam 46 makes two revolutions. Therefore, according to the same principle as the conventional ellipse drafting machine, the pencil assembly 48 can
Draw an ellipse on.

Here, the distance between the center needle 11 and the lower shaft 41 is a, and the lower shaft is
When the distance between 41 and the pencil assembly 48 is b, the major radius of the ellipse drawn is R, the minor radius is r, and the angle is α, the above equations (1), (2), and (3) hold.

In this ellipse drafter, the angle α of the ellipse drawn is
For the following reason, it depends on the position of the first friction wheel 31 in the radial direction of the first disc 26.

When the first disc 26 is rotated, the first shift pulley 16 rotates integrally with the first disc 26, so that the second beam support member
15 slides along the first beam 13 and the distance a changes.

Further, the first disc 26 rotates while the first disc 26 is pressed against the first friction wheel 31 by the spring 36 and the second disc 42 is pressed against the second friction wheel 32 by the spring 44. Then, this rotation is transmitted to the second disc 42 via the first friction wheel 31, the friction axle shaft 30, and the second friction wheel 32, and the second disc 42 also rotates in the opposite direction to the first disc 26. To do.

Further, when the second disc 42 is rotated in this way, the second shift pulley 45 rotates integrally with the second disc 42, so that the second beam 46 slides together with the pencil assembly 48, The distance b changes.

Here, the ratio of the rotation angle of the first disk 26 and the rotation angle of the second disk 42 is determined by the position of the first friction wheel 31 in the radial direction of the first disk 26, First disc 26
The value of (rotational angle of the second disc 42 / rotational angle of the first disc 26) becomes smaller as it moves toward the inner peripheral side of the disc (this is true even when the first disc 26 is rotated by the same angle). As the first friction wheel 31 moves toward the inner peripheral side of the first disc 26, the diameter of the arc of the locus drawn by the contact point between the first disc 26 and the first friction wheel 31 becomes smaller, and the friction axle 30 and The rotation angle of the second friction wheel 32, and thus the second disc.
Because the rotation angle of 42 becomes smaller).

Therefore, when the first friction wheel 31 is held at a fixed position, when the first disc 26 is rotated and the second beam support 15 is moved along the first beam 13 to change the distance a. The second beam 46, and thus the pencil assembly 48, moves in the length direction of the second beam 46 to a position where the distance b changes by a change amount that forms a constant ratio with respect to the change amount of the distance a. In this case, since the ratio of the amounts of change in a and b is constant, even if a and b change, the value of the angle α of the ellipse becomes constant due to the relationship of equation (3). Therefore, as described above, the angle α of the ellipse is determined by the position of the first friction wheel 31.

Then, when the rack 27 is moved by rotating the pinion 28 by rotating the ellipse angle setting knob 28a, the fork 33 and the first friction wheel 31 move in the radial direction of the first disc 26 together with this. The position of the first friction wheel 31, and thus the angle α of the ellipse, can be set by rotating the ellipse angle setting knob 28a. Further, the angle α of this ellipse can be read by the angle scale 34 designated by the position of the angle indicating projection 33a.

Next, the procedure for drawing an ellipse based on the major axis R and the angle α with this ellipse drafting machine will be described in detail.

First, when the scale support part of the drafter is first set on the paper surface 14, the "0 degree" of the scale of the major axis angle scale plate 5 is aligned with the scale indicator line 66 provided on the support material as shown in FIG. In this state, the first beam 13 is oriented in the horizontal direction on the paper surface 14 (hereinafter referred to as "0 degree direction"). Then, when the major axis direction of the ellipse to be drawn is "0 degree direction", the direction lock knob 12 is tightened at that position, and the central arm 9 and thus the first beam 13 is locked in the "0 degree direction" with respect to the paper surface 14. To do. Also, when the major axis direction of the ellipse to be drawn is at an angle with respect to the “0 degree direction”, the center knob 6 with the direction lock knob 12 loosened.
By rotating and adjusting the angle on the scale 5a of the major axis angle scale plate 5 to the scale support line 66 provided on the center support member 3, the direction of the central arm 9 and thus the first beam 13 is adjusted to the angle. After that, the direction lock knob 12 is tightened to lock the central arm 9 and thus the first beam 13 at that angle with respect to the paper surface 14.

Next, the second beam 46 is directed to a position aligned with the first beam 13 when viewed from the plane direction (this state is shown in FIG. 1).

Next, by rotating the upper intermittent lever 19, the upper shaft
Rotate 23 and resist upper spring 23 from upper shaft 23
And the first shift pulley 16 and then the first disc 26 are pushed up by the retaining plate 24,
26 is separated from the first friction wheel 31 or the lower interrupt lever 38
By rotating the sleeve 37 by rotating
Second disk by lowering 37 against case 25
42 is moved down, the second disc 42 is separated from the second friction wheel 32, and the first disc 26 and the second disc 42 are separated from each other with the linking relationship between the first disc 26 and the second disc 42 cut off. The distances a and b are set to 0 by rotating the plate 42 and aligning the zero points of the scales 13a and 46a of the beams 13 and 46 with predetermined portions.

Also, rotate the ellipse angle setting knob 28a to rotate the angle indicating protrusion 33a.
Is matched with a predetermined angle α of the elliptical angle scale 34, and then the elliptic angle lock knob 29 is tightened, and the tip of the male screw portion 29a is pressed against the rack 27 to lock the rack 27.

Next, the upper interrupting lever 19 and the lower interrupting lever 38 are rotated so that the spring 36 causes the first disc to move to the first friction wheel 31 and the spring 44.
With the second disc 42 pressed against the second friction wheel 32 respectively, when the first disc 26 is rotated in a predetermined direction, the second beam support 15 slides along the first beam 13, As the distance a increases, the second beam 46 slides and the distance b increases. Then, when the distance (a + b) matches the major radius R, the rotation of the first disc 26 is stopped, the first shift lock knob 22 is tightened, the wedge 21 is pressed against the first beam 13, and the second beam support 15 The first beam 13
The second shift lock knob 51 is tightened, the wedge 50 is pressed against the second beam 46, and the second beam 46 is locked to the pulley holder 40. This gives the distance a,
b is fixed respectively.

Next, the central needle 11 is pierced at the center of the ellipse, the direction lock knob 12 is loosened, the central knob 6 is held, and the central arm 9 is rotated together with the central knob 6. Thereby, an ellipse having an angle α and a major radius R is drawn by the pencil assembly 48 (at this time, the lock knob 54 is loosened, and the pulley holder 40 and the swivel pulley 39 can freely rotate with respect to the lower shaft 41. Keep it.
Also, after piercing the center needle 11 at the center of the ellipse,
The distance (a + b) may be adjusted to the major radius R).

Further, when an ellipse is drawn based on the short radius r and the angle α instead of the long radius R, instead of adjusting the distance (a + b) to the long radius R of the ellipse in the above procedure, the distance (ab) is changed to the short radius of the ellipse. It may be adjusted to the radius r.

Further, like the conventional ellipse drafting machine, when it is desired to draw an ellipse based on the major radius R and the minor radius r, not based on the angle α, the distances a and b are calculated from the equations (1) and (2). A =
The ellipse may be drawn as (R + r) / 2, b = (R-r) / 2. In this case, the upper interrupt lever 19 or (and)
By rotating the lower connecting lever 38, the linking relationship between the first disk 26 and the second disk 42 is cut so that the second beam support 15 and the second beam 46 can move independently of each other. Also, in this case, the distances a and b are the scales 13a and 13b of the beams 13 and 46.
It can be adjusted by 46a.

Although the above-mentioned embodiment is used by being attached to the scale support portion of the drafter, the ellipse drafting machine of the present invention may be configured to be used without being stuck to the scale support portion of the drafter. Needless to say.

〔The invention's effect〕

As described above, the ellipse drafting machine according to the present invention can draw an ellipse only by being given an angle and a major axis (or a minor axis), and it is easy to draw ellipses of different sizes at the same angle. An excellent effect can be obtained.

[Brief description of drawings]

FIG. 1 is a front view showing an embodiment of an ellipse drafting machine according to the present invention, FIG. 2 is a plan view showing the vicinity of the central knob in the embodiment, and FIG. 3 is a vertical cross section showing the vicinity of the central knob in the embodiment. 4 and 5 are plan views showing the center support member and the direction lock knob in the above embodiment, and FIG. 5 is VV of FIG.
6 is a plan view of the portion shown in FIG. 5, FIG. 7 is a sectional view taken along line VII-VII of FIG. 6, and FIG. 8 is a line VIII-VIII of FIG. 9 is a sectional view taken along line IX-IX in FIG. 8, and FIG.
FIG. 11 is a plan view showing a conventional elliptical drafter, and FIG. 12 is a front view showing another conventional elliptical drafter. 1 ... Center knob (center member), 9 ... Center arm (center member), 13 ... First beam, 14 ... Paper surface, 15 ... Second beam support, 16 ... First shift pulley, 17 …… First Synchromesh Rope, 26 …… First Disc, 27 …… Rack, 28 …… Pinion, 30 …… Friction Axle, 31 …… First Friction Wheel, 32 …… Second Friction Wheel, 33 ...... Fork, 36 ...... First spring, 39 ...... Swivel pulley, 42 ...... Second disc, 44 ...... Second spring, 45 ...... Second shift pulley,
46 …… second beam, 47 …… second synchromesh rope, 48 …… pencil assembly, 61,62 …… intermediate pulley, 63 …… center pulley, 64,65 …… timing belt.

Claims (1)

[Claims] 1. A center member rotated about a center of an ellipse to be drawn, a first beam supported by the center member in a direction parallel to a paper surface on which the ellipse is to be drawn, A second beam support body supported by the first beam and movable in the longitudinal direction of the first beam, and rotatably supported by the second beam support body in a plane parallel to the paper surface. A second beam extending in a direction parallel to the plane of the drawing, a drawing means supported by the second beam, the first beam and the second beam, and the central member And when the first beam is rotated,
A transmission unit that rotates the second beam twice while the first beam rotates once; and a predetermined ratio with respect to the amount of movement when the second beam support is moved in the length direction of the first beam. And a means for moving the drawing means in the lengthwise direction of the second beam by a movement amount that forms the predetermined ratio, and the predetermined ratio is variable.