JPH0473399B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a scale balancing device for a universal parallel ruler.

[Conventional technology]

Similar devices include Utility Model Application Publication No. 59-131893;
Those shown in No. 59-131894 and No. 59-131895 are known.

The above publication states that when the connection point of the elastic means to the rotating body is moved to the swing fulcrum of the elastic means for applying a balancing force to the rotating body with which the scale is linked, the elasticity of the elastic means becomes zero. discloses a technical idea that the scale can be perfectly balanced by setting the initial elasticity of the elastic means.

The elastic means includes a coil spring, a rope, a cylindrical elastic device, a curved spring, and the like.

[Problem that the invention seeks to solve]

To achieve perfect balance of the above scales,
If conventional elastic means were used, the device would become large, making it unsuitable for miniaturization. An object of the present invention is to provide a balance device suitable for downsizing.

[Means to solve problems]

In order to achieve the above object, the present invention has the following features on the drawing board 2:
A head 16 that can be moved to any position while maintaining a predetermined orientation, and a support substrate 18 for the head 16.
Scale mounting plate 28 rotatably mounted on the side
and scales 30 and 32 attached to the scale mounting plate 28,
A substantially middle portion of a support arm 54 is rotatably supported on the support substrate 18 side, and one side of the support arm 54 is attached to an eccentric portion of a rotating body 38 that interlocks with the scale mounting plate 28. is slidably engaged in conjunction with the diametrical displacement of the rotary body 38, so that a biasing force acts on the rotary body 38 in a direction opposite to the direction of rotation of the rotary body 38 due to the weight of the scales 30, 32, etc.; When a spring 56 is suspended between the eccentric portion of the rotary body 38 and the other side of the support arm 54, and the connection point of the spring 56 with the rotary body 38 is moved above the rotation center of the support arm 54. , the initial elasticity of the spring is set so that the elasticity of the spring is approximately zero.

[Effect]

When the head 16 is held stationary on the inclined drawing board 2 and the scales 30 and 32 are allowed to rotate freely relative to the head support substrate 18 side, the weight of the scales 30 and 32 exerts a rotational torque on the rotating body 38 in the direction of gravity. occurs, and the scales 30 and 32 try to rotate along the inclination of the drawing board 2 in the falling direction. On the other hand, the tensile force of the spring 56 connected to the support arm 54 acts on the rotating body 38, and rotational torque is generated in the rotating body 38. This rotational torque cancels out the rotational torque of the rotating body 38 in the direction of gravity, and the scales 30 and 32 are in a balanced state. In conjunction with the rotation of the rotating body 38, the support arm 54 rotates about its rotation center, and the spring 56 similarly swings about this rotation center as a swing fulcrum. Therefore, the rotation or swing fulcrum of the spring 56 is set at a constant position.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure 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 fixed to a support frame of a tiltable drafting table so that it can be fixed at a desired inclination angle between horizontal and vertical. 4 is a horizontal rail arranged on the upper side of the drawing board 2, and a horizontal cursor 6 is movably attached to this rail. The upper end of the vertical rail 8 is connected to the horizontal cursor 6. The lower end of the vertical rail 8 is movably placed on the drawing board 2 via a tail roller. A vertical cursor 12 is movably attached to the vertical rail 8, and a support substrate 18 of the head 16 is connected to this via a known double hinge mechanism 14.
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 circumferential surface of which is rotatably fitted into the inner circumferential surface of the multi-shaft 20. A mounting plate 24 is fixed to the upper part of the main shaft 22 with a nut, and a handle 26 is fixed to the mounting plate 24. A scale mounting plate 28 is attached to the lower end flange of the main shaft 22.
is fixed, and the scale 3 is fixed to the scale mounting plate 28.
0 and 32 are fixed. Reference numeral 34 denotes a tube body fixed to the mounting plate 24, and a first rotating body 36 is fixed to the outer peripheral surface of the tube body 34 with a screw 39 so as to be able to adjust the rotation angle with respect to the tube body 34. The rotating body 3
A gear 37 is formed on the lower pulley portion 6. Reference numeral 38 designates a tubular second rotary body, the outer circumference of which is rotatably supported by the support substrate 18 via a ball bearing. A timing belt 48 is stretched between teeth 45 formed on the pulley portion of the second rotating body 38 and teeth 37 of the first rotating body 36 . 42 is a screw shaft installed in the diametrical direction of the rotating body 38, and this has a molding 4.
4 are screwed together, and a piece member 46 is inserted into the recessed part of the molding 44.
are mated. The bridge member 46 is supported by a linear guide along the screw shaft 42 of the rotating body 38, and is configured to move along the screw shaft 42 in conjunction with the molding 44. 50 is a belt tension pulley rotatably attached to the bracket 52. Reference numeral 54 denotes a support arm, and an L-shaped portion 54a is vertically disposed approximately at the center of the support arm.
A horizontal portion of the character-shaped portion 54a is rotatably supported by a shaft 55 on a portion of the support substrate 18 located below the rotating body 38. A circumferential groove of the shaft portion of the bridge member 46 is fitted into one of the forked portions 54b of the support arm 54 so as to be slidable along the forked portion 54b. A coil spring 56 is suspended between a pin 57 protruding from the other end of the support arm 54 and a circumferential groove in the shaft portion of the bridge member 46 . When the shaft of the bridge member 46, that is, the connection point of the coil spring 56 to the rotating body 38, is moved onto the shaft 55, that is, on the rotation center axis of the coil spring 56, the initial tensile force of the coil spring 56 becomes zero. It is set as follows.

Next, the operation of this embodiment will be explained.

When the horizontal scale 30 is approximately parallel to the horizontal rail 4, the scales 30, 3 on the scale mounting plate 28
The rotational torque about the main shaft 22 due to the weight of the 2nd grade is maximum. At this time, the second rotating body 38
The rotation angle of the second rotating body 38 is adjusted so that the radius of the spring 56 as a rotational torque generating element is maximized. If the drawing board 2 is tilted, the scales 30, 32 and the scale mounting plate 28
Due to the weight of the main shaft 2, the scale mounting plate 28
2, a rotational moment is generated in the direction of rotation of the hour hand in FIG. The rotational moment of the scale mounting plate 28 is transmitted to the second rotating body 38 via the first rotating body 36 and the timing belt 48 . On the other hand, the tensile force of the coil spring 56 applies a rotational moment to the second rotating body 38 in a direction that offsets the rotational moment due to the weight of the scale 30 and the like. This allows the scale mounting plate 28 to remain stationary at any rotation angle. Incidentally, as the rotating body 38 rotates, the support arm 54 and the coil spring 56 rotate about the shaft 55.

Next, the operation of adjusting the distance between the spring connection point and the center of rotation of the second rotating body 38 will be described.

When the molding 44 is rotated, the molding 44 moves along the screw shaft 42, and in conjunction with the molding 44,
The bridge member 46 moves on the rotating body 38 in its radial direction. As the bridge member 46 moves along the screw shaft 42, the distance between the connection point of the coil spring 56 and the center of rotation of the rotating body 38 changes. scale 30,
When the inclination angle of the drawing board 2 is changed, the value of the load applied to the scale mounting plate 28 due to the weight of the scale mounting plate 32 changes in accordance with this change. Therefore, drawing board 2
When the inclination angle of the second rotating body 38 is changed, the amount of eccentricity of the coil spring 56 with respect to the rotating body 38 is adjusted by adjusting the rotation of the molding 44.
Adjust the amount of rotational torque in the balance direction.

〔effect〕

As described above, in the present invention, the swinging fulcrum of the spring is set at the center point of the support arm, and one of the support arms and the eccentric part of the rotating body are connected by the spring, so that the swinging fulcrum of the spring is set at the center point of the support arm. This has the advantage that the spring can be brought closer to the rotating body, the spring force of the spring can be used efficiently, and the device can be made smaller.

[Brief explanation of the drawing]

Figure 1 is a sectional view, Figure 2 is a plan view, Figure 3 is A
4 is a sectional view taken along line B-B, FIG. 5 is an external view of the support arm, and FIG. 6 is a plan view. 16...Head, 18...Support substrate, 20...
Multi-shaft, 22...Main shaft, 24...Mounting plate, 26...
Handle, 28... Scale mounting plate, 34... Tube body, 36... Rotating body, 38... Rotating body, 42...
Screw shaft, 44... Molding, 46... Bridge member, 54
... Support arm, 55 ... Axis, 56 ... Coil spring.

Claims (1)

[Claims] 1 A head 16 that can be moved to any position on the drawing board 2 while maintaining a predetermined orientation, and the head 1
In the flexible parallel ruler equipped with a scale mounting plate 28 rotatably attached to the support substrate 18 side of No. 6 and scales 30 and 32 attached to the scale attachment plate 28, a support arm 54 is attached to the support substrate 18 side. , and one of the support arms 54 is attached to an eccentric portion of a rotary body 38 that interlocks with the scale mounting plate 28 so that the eccentric portion is interlocked with the displacement of the rotary body 38 in the diametrical direction. The scale 30 of the rotating body 38 is slidably engaged with the scale 30,
A spring 56 is suspended between the eccentric portion of the rotary body 38 and the other side of the support arm 54 so that a biasing force acts on the rotary body 38 in a direction opposite to the direction of rotation due to the weight of the rotary body 32, etc.; The initial elasticity of the spring is set so that when the connection point of the spring 56 with the rotary body 38 is moved to the center of rotation of the support arm 54, the elasticity of the spring becomes almost zero. Scale balance device.