JPH0414640B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention provides that when a scale is placed on an inclined drawing board in a free state with respect to a non-rotating member of a head, the scale falls along the drawing surface in a falling direction. The present invention relates to a balance adjustment mechanism in a scale balance device for maintaining a stable stationary state without sudden rotation.

[Conventional technology]

Conventionally, various structures have been devised for scale balance devices for universal parallel rulers, but an eccentric cam is linked with the rotation of the scale, an elastic body is brought into elastic contact with this eccentric cam, and by this elastic contact force, Generally, the eccentric cam is configured to generate a rotational force in the opposite direction to the rotational force in the falling direction due to the scale's own weight, thereby balancing the scale.

[Problem that the invention seeks to solve]

A universal parallel ruler is usually mounted on a tiltable drawing board. Therefore, when the inclination of the drawing board is close to vertical, the falling force of the scale due to its own weight increases; on the other hand, when the inclination angle of the drawing board is gentle, the falling force of the scale decreases. Therefore, the force for balancing the scale must be varied as the inclination angle of the drawing board changes. In conventional equipment,
Adjustment of this balance force requires changing the spring force of the elastic body acting on the eccentric cam. In this case, since the adjustment of the balance force involves the expansion and contraction of the spring, there was a problem in that if the spring was stretched to increase the spring force, the spring would become fatigued. The present invention aims to eliminate the above-mentioned defects.

[Means to solve problems]

In order to achieve the above object, the present invention provides scale 3
An elastic means is applied to the rotating body 40, which rotates in conjunction with the rotation of the heads 0 and 32 relative to the support substrate 18, to apply a rotational force to the rotating body 40 in a direction that balances the falling rotation of the scales 30 and 32 in the direction of gravity. In the scale balance device for a universal parallel ruler, the rotary body 40 is formed into a cylindrical shape, the outer peripheral portion of the rotary body 40 is rotatably supported on the head support substrate 18, and the inner wall of the rotary body 40 is rotatably supported. A feed screw 42 is installed in the diametrical direction, a bridge member 50 is disposed in the hollow part of the rotating body 40 so as to be movable along the feed screw 42, and a molding 44 is installed on the feed screw 42.
The bridge member 50 is screwed onto the molding 44 so as to be interlocked with the movement of the molding 44 along the feed screw 42 but not with the rotational movement of the molding 44.
, and the operating end of the elastic means is connected to the bridge member 50.

[Effect]

In the above configuration, the rotational torque for scale balance of the rotating body 40 is determined by the amount of eccentricity on the rotating body 40 of the point of action of the elastic means that acts on the rotating body. Even if the elasticity of the elastic means is constant, as the amount of eccentricity increases, the torque of the rotating body 40, that is, the force for balancing the ruler increases, and as the amount of eccentricity decreases, the torque of the rotating body 40 decreases. This amount of eccentricity can be adjusted by rotating the molding 44 and
This can be done by moving the bridge member 50 along the axis 2 and moving the point of action of the elastic means on the rotating body 40 along the radial direction of the rotating body 40.

〔Example〕

The configuration of the present invention will be described in detail below based on embodiments shown in the accompanying drawings.

Reference numeral 2 denotes a drawing board, which is supported by a support frame of a drafting table which can be tilted so that a desired angle of inclination can be set between horizontal and vertical. 4 is a horizontal rail fixed to the upper edge of the drawing board 2, and a horizontal cursor 6 is movably attached to this rail. Said horizontal cursor 6
The upper end of the vertical rail 8 is connected to the upper end of the vertical rail 8. The lower end of the vertical rail 8 is movably placed on the drawing board 2 via a tail roller. 12 is a vertical cursor movably attached to the vertical rail 8, and the head 1 is connected to this via a known double hinge mechanism 14.
Six support substrates 18 are connected. A tubular double shaft 20 is fixed to the tube portion of the support substrate 18 with a nut. Reference numeral 22 denotes a tubular main shaft, the outer peripheral surface of which is rotatably fitted into the inner peripheral surface of the multi-shaft 20, and a mounting plate 24 is fixed to the upper part of the main shaft 22. A handle 26 is provided on the mounting plate 24.
is fixed. 28 is a scale mounting plate fixed to the flange of the main shaft 22, and the scales 30, 32 are fixed to this. 34 is a tubular body fixed to the mounting plate 24, and a tubular first rotating body 36 is rotatably fitted on the outer peripheral surface of this tubular body. A belt pulley 36a having teeth for a timing belt is fixed to the lower part of the rotating body 36. A screw hole is formed in the side wall of the rotating body 36, and the rotating body 36 is fixed to the tube body 34 by a fixing screw 38 that is threaded into the screw hole. 40 is a second rotating body, and the upper cylinder body 4
0a and a lower cylindrical body 40b, the cylindrical body 40a
and 40b are fixed by screws 41, 43 (see FIG. 5). A feed screw 42 is installed and fixed in the intermediate portion of the rotating body 40 in the diametrical direction of the rotating body 40, and an adjustment molding 44 is screwed into the screw 42. An inner ring of a ball bearing 46 is fitted and fixed in a concave groove formed on the outer periphery of the rotary body 40, and an outer ring of the ball bearing 46 is fitted and supported on the inner wall surface of a hole formed through the support substrate 18. has been done. A pair of curved guide surfaces 46 and 48 are formed on the cylindrical body 40b, and the guide surfaces 46 and 48
The outer circumferential curved surface of a bridge member 50 that rotatably fits into the recessed portion of the molding 44 is disposed inside the molding 44 to face each other. The guide surfaces 46 and 48 prevent the bridge member 50 from falling due to its own weight. A long hole 52 is provided in the bottom wall of the cylindrical body 40b along the feed screw 42, and a protrusion of the bridge member 50 is disposed in the long hole 52 so as to be movable along the long hole 52. A metal terminal 54a connected to one end of a flexible and bendable wire rope 54 is rotatably fitted into the protrusion of the bridge member 50. A belt pulley 40C having teeth for a timing belt is formed on the outer periphery of the rotating body 40.
A timing belt 56 is stretched between the belt pulley 36a and the belt pulley 36a. 58 is a coil spring, one end of which is a screw 60 protruding from the support substrate 18.
The rope 54 is connected to the other end. A pair of rope guides 62 and 64 are rotatably supported on the support substrate 18, and 66 is a tension pulley for the belt, which is rotatably supported on a bracket fixed to the support substrate 18. The metal terminal 54a, that is, one end of the rope 54 is connected to the bridge member 50.
Assuming that the coil spring 58 is removed from the rope and placed at the end E where the rope direction is restricted by the rope guides 62 and 64, the initial position of the coil spring 58 is set so that the tension on the rope 54 by the coil spring 58 is exactly zero, and The spring 58 has a spring constant corresponding to the rotational torque generated in the first rotating body 36 due to the weight of the scale mounting plate 28, scales 30, 32, etc. Note that the belt pulley 36a may be fixed to the scale mounting plate 28. In addition, the above coil spring 5
8. The rope 54 constitutes elastic means that applies a rotational torque for balance to the rotating body 40. This resilient means is not particularly limited to the structure shown.

Next, the operation of this embodiment will be explained.

In a state where the drawing board 2 is tilted at a predetermined angle and the scale mounting plate 28 is freely rotatable with respect to the support substrate 18, the scale mounting plate 28, the scale 3
A rotational torque T about the main shaft 22 is generated in the first rotating body 36 due to its own weight of 0.0, 32, etc. The magnitude of this rotational torque T and the rotational torque T' acting on the second rotary body 40 due to the elasticity of the coil spring 58 are set to be the same, and their directions are opposite. Therefore, the scale mounting plate 28 is the inclined drawing plate 2.
There is no sudden rotation with respect to the support substrate 18 on the top. By rotating the handle 26, the scale mounting plate 28 can be rotated 360 degrees.
Therefore, the scales 30 and 32 are attached to the support substrate 1 of the head.
Even if the scales 30 and 32 are set at a desired angle with respect to the tilted drawing board 2 and the handle 26 is released, the scales 30 and
Maintain a stable stationary position relative to the head at the top. When the second rotating body 40 rotates as the scales 30 and 32 rotate, the coil spring 5 of the rotating body 40
The rotational torque T' due to 8 changes in a sine curve as shown in FIG. Since the rope 54 does not get caught on the rotating body 40 even if the second rotating body 40 rotates 360 degrees or more, the scale mounting plate 28 can be rotated any number of times.

Next, the operation for adjusting the magnitude of the rotational torque T' will be explained.

When the molding 44 is rotated, the molding 44 moves along the feed screw 42, thereby causing the bridge member 50 to move along the feed screw 42. As the bridge member 50 moves, one end 54a of the rope 54 moves in the radial direction of the second rotating body 40. As the one end 54a of the rope moves relative to the rotating body 40, the distance between the center of the rotating body 40 and the point of action of the spring, that is, the radius as a rotational torque generating element changes, and the rotational torque T' of the rotating body 40 changes. Change.
When the inclination angle of the drawing plate 2 is changed, the value of the load W applied to the center of gravity of the scale mounting plate 28 due to the weight of the scales 30, 32, etc. changes in accordance with this change. When the drawing board 2 is vertical, the above load W
is maximum, and when drawing board 2 is horizontal, the above load W
becomes zero. Therefore, when the inclination angle of the drawing board 2 is changed, by adjusting the rotation of the molding 44, the coil spring 58 is adjusted in response to the rotational torque T generated in the first rotating body 36 by the load W. The magnitudes of the rotational torques T' generated in the second rotating body 40 due to the tensile load can be matched.

Note that the first rotating body 36 and the second rotating body 40
They may be interlocked by meshing gears, and the coupling mechanism between the rotating bodies 36 and 40 is not particularly limited to the illustrated belt transmission mechanism. Further, the second rotating body 40 may be formed of a single cylindrical body 70, as shown in FIG.

As described above, in the present invention, the point of action of the elastic means on the rotating body that rotates in conjunction with the rotation of the scale can be moved in the radial direction of the rotating body, so that the balance force of the rotating body can be easily applied to the inclination angle of the drawing board. Moreover, since this adjustment operation does not involve displacement of the elastic means in the direction of expansion and contraction, the elastic means can be operated within a predetermined expansion and contraction range, and fatigue of the elastic means can be prevented. be able to.

[Brief explanation of drawings]

Fig. 1 is a plan view, Fig. 2 is a plan view, Fig. 3 is a sectional view, Fig. 4 is a sectional view, Fig. 5 is a sectional view taken along line A-A, and Fig. 6 is a sectional view showing another embodiment. 7 are explanatory diagrams. 2...Drawing board, 4...Horizontal rail, 6...Horizontal cursor, 8...Vertical rail, 12..., Vertical cursor, 1
6...Head, 18...Support board, 20...Multi-shaft, 22...Main shaft, 24...Mounting plate, 26...Handle, 28...Scale mounting plate, 32, 33...
...Scale, 36...First rotating body, 36a...
Belt pulley, 40... Second rotating body, 42...
Feed screw, 44... Molding, 50... Bridge member, 5
4... Rope, 56... Timing belt, 58
...Coil spring.

Claims (1)

[Claims] 1 Support substrate 18 for heads of scales 30 and 32
A resilient means, the other end of which is connected to the support substrate 18, is applied to the rotating body 40, which rotates in conjunction with the rotation of the scales 30 and 32, to apply a rotational force to the rotating body 40 in a direction that balances the falling rotation of the scales 30 and 32 in the direction of gravity. In the scale balance device for a universal parallel ruler, the rotary body 40 is formed into a cylindrical shape, the outer peripheral portion of the rotary body 40 is rotatably supported on the head support substrate 18, and the rotary body 40 is A feed screw 42 is installed in the inner wall in the diametrical direction, a bridge member 50 is disposed in the hollow part of the rotating body 40 so as to be movable along the feed screw 42, and a molding 44 is screwed onto the feed screw 42, The bridge member 50 is connected to the molding 44 so as not to be interlocked with the rotational movement of the molding 44 but to be interlocked with the movement of the molding 44 along the feed screw 42, and the bridge member 50 is subjected to the action of the elastic means. A balance adjustment mechanism characterized by connected ends.