JP2524855B2 - 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 an equilibrium device for a ruler that prevents the ruler from rapidly rotating in the falling direction so that the ruler maintains a stable stationary state.

[Conventional technology]

A circular eccentric cam is fixed to the vertical axis rotatably supported on the substrate of the head, and a roller urged by a spring is repelled on the outer peripheral surface of the eccentric cam to balance the ruler connected to the vertical axis. Such a device is disclosed in JP-A-60-52399. In this device, a plurality of springs are selectively acted on the rollers according to the inclination of the drawing board. Further, in another embodiment, the spring fulcrum for one spring is changed according to the inclination of the drawing board, and the resilience of the spring with respect to the roller is proportionally changed by these configurations.

Japanese Patent Laid-Open No. 59-199299 discloses a head that is movable to an arbitrary position while maintaining a predetermined orientation on a drawing board, and a longitudinal axis that is rotatably supported by a substrate of the head and that is connected with a ruler. A rotating body fixed to the vertical axis, and a second rotating body rotatably supported by a substrate of the head that rotates in association with rotation of the rotating body, and one of which is supported by the head substrate. A spring connected to the eccentric part of the second rotary body and applying a rotational torque to the second rotary body in a direction opposite to the rotational direction due to the weight of the straight edge ruler; There is disclosed an equilibrium device for a ruler in a universal parallel ruler in which the point of action of the second rotary body is movable in the radial direction of the second rotary body.

The structure in which the means for proportionally changing the elastic force of the roller with respect to the spring and the action point of the spring can be moved in the radial direction of the second rotating body have a ruler when the balance force with respect to the ruler is adjusted according to the inclination of the drawing plate. The balance state of the ruler is obtained by keeping the similarity of the sine curve characteristics of the rotational torque for balance from changing.

[Problems to be solved by the invention]

The configuration of proportionally changing the spring force using a plurality of springs is complicated and expensive. In addition, the technical idea of changing the fulcrum for one spring requires the use of a U-shaped special shaped spring having high strength, which is expensive.

Further, in the configuration in which the action point of the spring can be changed in the radial direction of the second rotating pair, when the ruler is rotated 360 degrees, the second rotating body also rotates 360 degrees. , The spring connected to the second rotating body is the spring of the second rotating body.
It was necessary to connect them so as not to block 0 degree rotation, and there was a defect that the configuration became complicated.

The present invention aims to eliminate the above defects.

[Means for solving problems]

In order to solve the above-mentioned problems, the present invention rotatably supports a vertical axis 22 on a head substrate 18 which is supported for parallel movement on a drawing board, and a ruler mounting plate 28 is fixed to a lower portion of the vertical axis 22. Then, in the device in which the handle 24 is fixed to the upper part of the vertical axis 22,
An eccentric cam 22 is fixed to the vertical axis 22, a lever 34 is rotatably supported on the head substrate 18, and one end of the head substrate 18 is supported by a portion eccentric with respect to the rotation center of the lever 34. The other end of the coil spring 42 is attached to the eccentric cam 22 by the elastic force of the coil spring 42 so that one of the levers 34 passes through the rotating body 48.
So as to elastically contact the outer peripheral surface of the coil spring 42.
The connecting portion to the lever 34 is movable and adjustable along the direction in which the amount of eccentricity of the lever 34 with respect to the rotation center changes.

[Action]

The lever 34 is biased in the rotational direction by the tensile elastic force of the coil spring 42, and one end of the lever 34 is elastically attached to the outer peripheral surface of the eccentric cam 22 fixed to the vertical axis 20 to which the ruler is connected via the rotating body 48. Contact. On the eccentric cam 22, due to the elastic contact force from the rotating body 48, a rotating torque for ruler balancing is generated in a direction opposite to the rotating torque of the vertical axis 20 generated by the weight of the ruler. The rotation torque for this ruler balance is
It can be changed by moving the connecting portion for the lever 34 along the direction in which the amount of eccentricity with respect to the rotation center of the lever 34 changes. Even if the connecting portion changes, the sine curve characteristic of the rotary torque for ruler balance accompanying the rotation of the vertical axis 20 changes within a range where the similarity does not collapse. The ruler can be held in a balanced state in accordance with the inclination angle of.

Since the spring for biasing the lever 34 uses the commercially available inexpensive coil spring 42, the structure can be simplified, and the lever 34 is interlocked with this even if the vertical axis 20 rotates 360 degrees. Since it does not rotate 360 degrees and only swings within a set angle range, it is not necessary to provide a special structure for connecting the coil spring 42 to the lever 34.

〔Example〕

The configuration of the present invention will be described in detail below with reference to an embodiment of a track type universal parallel ruler shown in the accompanying drawings. still,
The present invention is not particularly limited to the track type universal parallel ruler.

Reference numeral 2 is a drawing plate, which is fixed to a support frame of a drafting table that can be releasably fixed at an inclination angle of a bar. 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 attached to the drawing board 2 via the tail roller.
It is mounted so that it can run freely. 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 28 is fixed to a lower portion of the vertical axis 20. Has been done. A horizontal ruler 30 and a vertical ruler 32 are fixed to the ruler mounting plate 28. 37 is an L-shaped lever, the middle part of which is rotatably supported by the substrate 18 by a shaft 36.
A screw 38 is rotatably supported by a pair of rising portions formed on the lever 34 so as not to move in the axial direction.
A graduated molding 40 is fixed to one end of 38. 42
Is a coil spring whose one end engages with a pin 44 protruding from the substrate 18, and the other end of which is engaged with a shaft portion 46a of a top 46 screwed to the screw 38. A rotating body 48 formed of a roller is rotatably supported at one end of the lever 34, and the rotating body 48 is driven by the tension force of the coil spring 42 to move the cam.
It makes elastic contact with the outer peripheral surface of 22. When the ruler 30 is horizontal to the horizontal rail 4, the longitudinal direction of the spring 42 is set to be perpendicular to the screw 38.

It should be noted that the internal structure of the head 16 shown in FIG. 2 shows a basic configuration in which details are omitted.
The known angle fixing mechanism and the index mechanism between 18 and the like are omitted.

 Next, the operation of this embodiment will be described.

When the vertical plate 20 is tilted and the vertical cursor 12 is fixed to the vertical rail 8, the vertical axis 20 is released from the base plate 18 and the vertical axis 20 is allowed to rotate freely.
The rotating torque generated on the vertical axis 20 due to the weight of
Is horizontal with respect to the horizontal rail 4, and the state is zero degrees, the maximum is almost obtained at this zero degree. That is, ignoring the weight of the ruler 32, when the ruler 30 is changed from +90 degrees to −90 degrees, the rotational torque of the vertical axis 20 changes in a sine curve.
Therefore, if the vertical axis 20 is provided with a rotation torque having a sine curve characteristic that cancels the rotation torque due to the weight of the ruler 30, the ruler 30 can be statically balanced on the drawing board 2 at an arbitrary rotation angle.

In FIG. 5, the rotational torque T applied to the eccentric cam 22 by the coil spring 42 is: T = F × l where F is the elastic force of the rotating body 48 due to the force of the spring 42, and 1 is the elastic force of the rotating body 48. It is a radius as an element for generating the rotational torque of the cam 22 by the force F. In this embodiment, the ruler 30
That is, the shape of the cam 22 is determined so that the torque T becomes a sine curve when the cam 22 is rotated, and the radius 1 is determined. When the inclination angle of the drawing board 2 is changed, the ruler drop rotation 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 the ruler drop rotation torque decreases when the inclination of the drawing board 2 is moderated. When the spring force F0 is adjusted by changing the amount of deflection when the inclination angle of the drawing plate 2 is changed, if the spring force is strengthened, the spring force F0 becomes F0 + A (A is the increment of the spring force), When weakened, it becomes F0-A (A is the decrease in spring force). The rotational torque T of the eccentric cam due to the spring force when the spring F0 is adjusted to be weakened from the state of FIG. 7 (a) is T = (F0−A) · l1 / l2 × l, and the characteristic of this torque T Does not become a sine curve as shown in FIG. 7 (b). The reason is that when the spring 42 is adjusted in the flexing direction, the flexing spring force change characteristic of the spring 42 moves in parallel.

When the spring force F0 is increased, T = (F0 + A) · 10 / l2 × l. However, as mentioned above, the vertical axis depends on the weight of the ruler 30.
The characteristic of the rotational torque acting on 20 is a sine curve.
Therefore, if the rotational torque of the eccentric cam 22 due to the spring force for balancing with the rotary sulcus is not a sine curve, the ruler 30, that is, the vertical axis 20 cannot be perfectly balanced. In this embodiment, when the molding 40 is rotated, the screw 38
The top 46 moves along with the top 46, and the movement of the top 46 moves the point of action of the coil spring 42 on the lever 34 in the direction in which the radius l1 as the rotational torque generating element of the lever 34 changes, whereby the spring force F The deflection / spring force change characteristic straight line changes in proportion to the characteristic straight line before adjustment.

In this embodiment, the elastic force of the rotating body 48, that is, the spring force, is F, the spring force of the coil spring 42 is F0, and the center of rotation 36 of the lever 34.
, And the distance between the top 46 and l1 and the distance between the center of rotation 36 and the contact point between the rotating body 48 and the cam 22 are l2, F = (F0 × l1) / l2 = F0 × l1 / l2 When you rotate the mall 40 from and change l1,
The change characteristic of the spring force F with respect to the deflection is shown in Fig. 4 (a).
It changes proportionally as shown in (b). Therefore, the cam
The rotation torque T of the spring 42 of 22 changes in a sine curve with the rotation of the ruler 30, and the vertical axis 20, that is, the balance of the ruler 30 is maintained.

In the above description, the weight of the vertical ruler 32 is neglected, but in reality, the vertical axis 20 has the ruler mounting plate 28 and the ruler 3
Since the weights of 0 and 32 act, the maximum point and the minimum point of the rotational torque due to these total weights are angles slightly rotated clockwise in FIG. 3 as compared with the case where the weight of the ruler 32 is ignored. .

In FIG. 6, the straight line A is the characteristic of the spring force F when l1 / l2 = 1, B is l1 / l2 = 1/2, C is l1 / l2 = 1/10, and D is l1 =
This is a characteristic of the spring force F of 0, and these are in a proportional change relationship with each other.

In the present embodiment, when the torque is adjusted as described above, the spring is not displaced in the longitudinal direction thereof, but the lever of the spring is used.
Since the action point on 34 is displaced in the direction in which the radius of the lever 34 as the torque generating element changes, the drawing plate 2 approaches zero degrees even for the cam 22 made for the steep slope. Sometimes a gap does not occur between the rotating body 48 and the cam 22.

〔effect〕

Since the present invention is configured as described above, the ruler can be balanced with a simple configuration.

[Brief description of drawings]

1 is a sectional view taken along the line BB, FIG. 2 is a sectional view taken along the line AA, FIG. 3 is a plan view, FIG. 4 is an explanatory view, FIG. 5 is an explanatory view, and sixth.
The figure is an explanatory diagram, and FIG. 7 is an explanatory diagram. 2 ... Drawing board, 4 ... Horizontal rail, 6 ... Horizontal cursor, 8 ...
… Vertical rail, 12 …… Vertical cursor, 16 …… Head, 18 ……
Substrate, 20 …… vertical axis, 22 …… eccentric cam, 24 …… handle,
28: Ruler mounting plate, 30: Horizontal ruler, 32: Vertical ruler,
34 …… Lever, 36 …… Shaft, 38 …… Screw, 40 …… Maul, 42
...... Coil spring, 44 ...... pin, 46 ...... top, 48 ...... rotating body.

Claims (1)

(57) [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, and 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,
The other end of the coil spring 42 whose one end is supported by the head substrate 18 is eccentric to the center of rotation of the lever 34, and the elastic force of the coil spring 42 causes one of the levers 34 to rotate.
So as to make elastic contact with the outer peripheral surface of the eccentric cam 22 via 48,
A ruler balancing device in a universal parallel ruler, characterized in that the connecting portion of the coil spring 42 to the lever 34 can be moved and adjusted along a direction in which the amount of eccentricity with respect to the rotation center of the lever 34 changes. .