JPH0751396B2 - Balancer for Ruler on Universal Parallel Ruler - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a universal parallel ruler, in which the ruler is attached to the head substrate by its own weight when the ruler is free from the head substrate on an inclined drawing board. The present invention relates to a ruler balancing device for maintaining a stable stationary state without rapidly rotating in a falling direction.

[Conventional technology]

In this type of device, as shown in FIG. 8, a circular eccentric cam 22 is fixed to a vertical axis 20 to which a ruler is connected, an L-shaped lever 34 is rotatably supported by a shaft 36, and One end of the coil spring S is connected to one of the levers 34, and the tension of the coil spring S causes the other of the levers 34 to elastically contact the outer peripheral surface of the eccentric cam 22 via a rotating body 48 composed of a roller. It is known that the other end of S is connected to one end of a screw rod 50 which can be moved and adjusted in the longitudinal direction by the rotation of the molding 52. When the head is fixed on the inclined drawing plate and the vertical axis 20 is freely rotated with respect to the head substrate, the vertical axis 20 tries to rotate rapidly in the clockwise direction in FIG. 8 due to the weight of the ruler connected thereto. However, due to the elastic force from the rotating body 48, the eccentric cam 22 is given a counterclockwise rotational torque, and this rotational torque and the rotational torque of the vertical axis 20 due to the weight of the ruler may be offset. Since the elasticity of the spring S and the shape of the cam 22 are set on the vertical axis 20, the vertical axis 20 maintains a balanced state without rapidly rotating due to the weight of the ruler. The spring S
The amount of elasticity of can be adjusted by rotating the molding 52.

[Problems to be solved by the invention]

From the +90 degrees of the ruler to -90 due to the weight of the ruler on the vertical axis 20
The torque change with the rotation of a degree becomes a sine curve. Therefore, the torque generated in the eccentric cam 22 due to the elasticity of the spring S also needs to change in a sine curve as the ruler rotates.

The force acting on the cam 22 of the spring S is F, and the eccentric cam of the rotating body 48 is
A shortest distance between the extension line of the action direction with respect to 22 and a straight line parallel to the line and passing through the rotation center of the eccentric cam 22 is 1 (that is, the radius of the cam as a torque generating element), and is generated in the eccentric cam 22 by the spring S. When the rotational torque is T, T = Fl ∴ l = T / F From the above equation, the eccentric cam 22 rotates along with its sine curve at the time of elevation of the drawing board (for example, at a tilt angle of 60 degrees). The shape of the eccentric cam 22 is determined so that the ruler balancing torque having the torque characteristics of

In this way, the cam for the elevation of the drawing is formed, but when the drawing board is tilted at an angle close to the horizontal direction, the rotating torque acting on the vertical axis becomes small due to the weight of the ruler.
In response to this, it is necessary to weaken the force of the spring S. This operation is performed by rotating the molding 52 and moving the screw 50 to the right in FIG. When the force of the spring S is thus weakened, the characteristic of the torque T of the eccentric cam 22 changes as shown in FIG. 11 (b). In addition, tilt the board horizontally and
When the force of the spring S is weakened, as shown in FIG.
The characteristics of the torque T of 22 changed, and the ruler was moved from the +90 degree position to −
When it rotates in the 90 ° direction, the spring force on the cam 22 becomes zero in the middle, and as shown in FIG.
There is a problem that it is not elastically contacted with 22 and a gap d is formed between the rotating body 48 and the cam 22, which makes it impossible to balance the ruler.

The present invention aims to solve the above problems.

[Means for solving problems]

In order to solve the above problems, the present invention provides a lever 34 for imparting a rotating torque for a ruler balance to an eccentric cam 22 to which a ruler is connected. Connecting the spring means 42 having
By means of this, a rotational torque is applied to the lever 34, and the spring means 42 is supported by a spring holder 46 which is displaceable in the longitudinal direction thereof.

[Action]

When the drawing plate is steeply inclined and it is desired to exert a strong balance torque on the eccentric cam 22, the spring holder 46 is moved from the eccentric cam 22 so that the strong elastic region of the spring means 42 acts on the eccentric cam 22. Adjust the movement in the direction of separation. When the drawing plate 2 is in the gently inclined state, the spring holder 46 is moved and adjusted in the direction of approaching the lever 34, and the spring means 42 is contracted as a whole. As a result, the weak elastic region of the spring means 42 acts on the eccentric cam 22 via the lever 34. As a result, there is no gap between the eccentric cam 22 and the rotating body 48.

〔Example〕

Hereinafter, the configuration of the present invention will be described in detail with reference to the embodiments shown in the accompanying drawings.

Reference numeral 2 is a drawing plate, which is fixed to a support frame of a drafting table which can be fixed at a desired inclination angle. Reference numeral 4 denotes a horizontal rail arranged on the upper side of the drawing board 2, to which a horizontal cursor 6 is movably attached. An upper end of a vertical rail 8 is connected to the horizontal cursor 6. The lower end of the vertical rail 8 is movably mounted on the drawing board 2 via a tail roller. Reference numeral 12 denotes a vertical cursor movably attached to the vertical rail 8, to which a substrate 18 of a head 16 is connected via a well-known double hinge mechanism 14.

In FIG. 2, reference numeral 20 denotes a vertical axis rotatably supported by the head substrate 18, a circular eccentric cam 22 and a handle 24 are fixed to an upper portion of the vertical axis 20, and a ruler mounting plate 26 is provided below the vertical axis 20. Is fixed. A horizontal ruler 30 and a vertical ruler 32 are fixed to the ruler mounting plate 26. 34 is an L-shaped lever,
An intermediate portion thereof is rotatably supported on the substrate 18 by a shaft 36. A screw is provided on the rising portion formed on the head substrate 18.
38 is rotatably supported so as not to move in the axial direction, and a graduated molding 40 is fixed to one end of the screw 38.
Reference numeral 46 denotes a spring holder screwed to the screw 38, and the lower surface of the spring holder slidably contacts the head substrate 18. When the molding 40 is rotated, the spring holder 46 is configured to move along the screw 38 in a direction toward or away from the lever 34 according to the rotation direction of the screw 38. 42 is a spring means composed of a plurality of coil springs a, b, c, d having different lengths and spring constants. One side of the spring means 42 is engaged with the spring holder 46 and the other side is a lever 34. Is engaged with the vertical portion of the.

The flexible spring force characteristic X of the spring means 42 approximates a quartic curve as shown in FIG. As shown in FIG.
If there is one strong spring S1 and one weak spring S2 with a long stroke, at the spring action exchange point Z shown in FIG.
Since the spring force changes greatly, the number of springs having different lengths and spring constants is increased to smooth the change characteristic curve X of the spring means with respect to the amount of deflection of the spring means, as shown in FIG. It is desirable that the curve be a multi-order curve. At one end of the horizontal portion of the lever 34, a rotating body 48 composed of rollers is rotatably supported, and the rotating body 48 is elastically contacted with the outer peripheral surface of the cam 22 by the pulling force of the spring means 42. .

It should be noted that the internal structure of the head 16 shown in FIG. 2 shows a basic configuration with details omitted, and includes a ruler mounting plate 26 and a substrate 18.
The known angle fixing mechanism, index mechanism, etc. between and are omitted.

Next, the operation of this embodiment will be described. When the drawing board 2 is tilted at a desired angle and the vertical cursor 12 is fixed to the vertical rail 8 and the vertical axis 20 is freely rotated with respect to the head substrate 18, the vertical axis 20 is determined by the weight of the rulers 30 and 32. 20th, 3rd
In the figure, a rotational torque is generated in the clockwise direction, and the horizontal ruler 30 tries to fall rapidly from the state parallel to the horizontal rail 4 in the clockwise direction around the rotation center of the vertical axis 20 along the drawing board 2. To do. The rotation torque generated on the vertical axis 20 is almost maximum when the horizontal ruler 30 is horizontal to the horizontal rail 4 at zero degrees, and is almost minimum when the ruler is plus and minus 90 degrees. It changes with a sine curve.
Therefore, if the vertical axis 20 is provided with a rotational torque having a sine curve characteristic that cancels out the rotational torque due to the weight of the rulers 30 and 32, the ruler 30 and 32 can be statically balanced on the drawing board 2 at an arbitrary rotation angle. . Eccentric cam 22 by spring means 42
The rotational torque T applied to is: T = F × l where F is the spring force acting on the cam 22 via the rotating body 48 of the spring means 42, and 1 is the eccentric cam 22 due to the elastic force of the rotating body 48.
Is a radius as an element that generates a rotating torque. In this embodiment, the flexural spring force change characteristic has a multi-order curve X (fourth order).
(See the figure) When using spring means 42 similar to
The shape of the eccentric cam 22 is determined based on the radius 1 so that the balance torque generated on the vertical axis 20 with the rotation of the sine curve becomes a sine curve. When the inclination angle of the drawing board 2 is changed, the rotational torque applied to the vertical axis 20 changes depending on the weight of the rulers 30 and 32. When the inclination of the drawing board 2 is set to a steep angle, the ruler drop rotation torque increases, and when the inclination of the drawing board 2 is gentle, the ruler drop rotation torque becomes small. When the drawing board 2 is inclined at 60 degrees to the floor,
Rotate the mall 40 and adjust the distance of the spring holder 46 to the lever 34 with the preset scale, and adjust the horizontal ruler 30
The spring use area is set so that the sine curve torque T is obtained in the eccentric cam 22 when is rotated from +90 degrees to −90 degrees. The sine curve torque T substantially coincides with the constant drop rotation torque when the drawing board 2 is 60 degrees, both act on the vertical axis 20 in the opposite direction, and the rulers 30 and 32 balance.

When the drawing board 2 is tilted at 6 degrees to the floor,
40 is rotated to bring the spring holder 46 closer to the lever 34, and the distance to the lever 34 is adjusted by a preset scale, and the use range of the spring characteristic is set to H in FIG. To obtain the torque for use T '. This torque T '
Is almost a sine curve, which is approximately the same as the ruler drop rotation torque, and the balance of the ruler is maintained.

The spring means whose deflection / spring force change characteristic is a multi-order curve characteristic is a combination of a plurality of types of springs having different spring constants, or a combination of a plurality of springs having different lengths,
Alternatively, it can be configured by a combination of a plurality of springs having different spring constants and lengths.

In this embodiment, four springs a, b, c, d
The order curve characteristic X shown in FIG. 7 and FIG. 7 was obtained. However, the order curve characteristic X is not particularly limited to the configuration obtained by a plurality of springs, and as shown in FIG. A taper-shaped conical coil spring 80 may be used. In addition, as shown in FIG. 13a, the leaf spring 82 having a width that decreases in one direction.
The above-mentioned multi-order curve characteristic X can also be obtained by a so-called bamboo coil spring formed by winding. FIG. 14 shows a coil spring 84 in which the winding diameter is the same and the leads change in one direction.
Therefore, the above-mentioned multi-order curve characteristic X can also be obtained by this spring.

〔effect〕

As described above, according to the present invention, the eccentric cam is pressed through the roller by using the spring means having the characteristic of several orders, so that the spring force of the spring means is small even when the inclination of the drawing board is gentle. By using the area, the roller can be elastically contacted with the eccentric cam, and the rotating torque for the ruler balance can be applied to the eccentric cam, and there is a gap between the roller and the eccentric cam, making it impossible to balance. There is an effect that can prevent the situation.

[Brief description of drawings]

1 is a sectional view taken along line BB, FIG. 2 is a sectional view taken along line AA, FIG. 3 is a plan view, FIG. 4 is an explanatory view, FIG. 5 is a plan view, and FIG.
Drawing is explanatory drawing, Drawing 7 is explanatory drawing, Drawing 8 is a top view, Drawing 9 is an explanatory view, Drawing 10 is a top view, Drawing 11 is an explanatory view, Drawing 12 is an outline drawing, Drawing 13 Is an external view, and FIG. 14 is an external view. 2 …… Drawing board, 4 …… Horizontal rail, 6 …… Horizontal cursor, 8 …… Vertical rail, 12 …… Vertical cursor, 16 …… Head, 18 …… Board, 20…
… Vertical axis, 22 …… Eccentric cam, 24 …… Handle, 28 …… Ruler mounting plate, 30 …… Horizontal ruler, 32 …… Vertical ruler, 34 …… Lever, 36…
… Axis, 38 …… Screw, 40 …… Mole, 42 …… Spring means, 44 ……
Pin, 46 …… Spring holder, 48 …… Rotating body

Claims (1)

[Claims] 1. A vertical axis 20 is rotatably supported on a head substrate 18 which is supported so as to be movable in parallel on the drawing board, and a ruler mounting plate 28 is fixed to a lower portion of the vertical axis 20 to fix the vertical axis 20 of the vertical axis 20. Handle on top 24
In the device fixed, the eccentric cam 22 is fixed to the vertical axis 20, and the lever 34 is rotatably supported on the head substrate 18,
A spring holder 46 is provided on the head substrate 18 so as to be movable and adjustable with respect to the lever 34, and the spring holder 46 and the lever are provided.
A spring means (42) having a characteristic of changing the spring force with respect to the amount of deflection and having a degree-of-order curve approximation characteristic is installed between the portion of the lever (34) and the portion that is eccentric with respect to the center of rotation, and the lever (34) is used by the elastic force of the spring means (42). One side of the eccentric cam 22
A balancer for a ruler in a universal parallel ruler, which is elastically contacted with the outer peripheral surface of the.