JPH0456759B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention provides a universal parallel ruler in which when the scale is placed in a free rotating state relative to the non-rotating member of the head on an inclined drawing board, the scale does not suddenly rotate in the falling direction along the drawing board and maintains a stable stationary state. The present invention relates to a scale balance device for maintaining scale balance. In FIG. 4, a spring 6 attached to the non-rotating member side of the head is attached to the rotating body 4 to which the scale 2 is connected, and the tensile force of the spring 6 is applied to the eccentric part of the rotating body 4, so that the scale 2 In a scale balance device that cancels out the rotational torque of the rotating body 4 due to the weight, when the scale 2 is at approximately +90 degrees, the tensile force of the spring 6 is zero, and the rotating body 4 is centered around the multiple axis 8 due to the weight of the scale 2. Set the rotation torque to zero. In the above configuration, when the rotating body 4 is rotated so that the scale 2 becomes zero degrees as shown in FIG. 4B, a tensile load of the spring acts on the rotating body 4, for example, 5 kg. At this time, the rotational torque of the rotating body 4 due to the spring 6 becomes maximum. Furthermore, when the rotating body 4 is rotated in the direction of rotation of the hour hand until the scale 2 reaches -90 degrees (see Figure 4C), the spring force becomes 10 kg,
The rotational torque due to the spring force of the rotating body 4 becomes zero. In this case, a load of 10 kg is applied between the rotating body 4 and the multiple shaft 8 due to the spring force. This increases the pressure load of the rotating body 4 on the multiple shaft 8, which adversely affects the durability of the head and the angular accuracy of the ruler 2. However, as shown in FIGS. 4d to 4f, a gear 9 is rotatably supported by a shaft 10 on a non-rotating member of the head, and teeth provided on the outer periphery of each of the rotating bodies 4 are meshed with the gear 9. In the configuration in which the spring 6 is attached to the eccentric part of the scale 2, the scale 2 is +
At 90 degrees, the spring force is zero and the torque of gear 9 is set to zero. When scale 2 is at zero degrees,
The spring force becomes 5 kg, and the torque of gear 9 becomes maximum. When the gear 9 is rotated until the scale 2 reaches -90 degrees as shown in FIG. 4f, the spring force becomes 10 kg, but the rotational torque of the gear 9 due to the spring force is zero. In this case, since only the rotating body torque of the gear 9 acts on the rotating body 4, the pressure load due to the spring 6 acting between the rotating body 4 and the multiple shaft 8 is zero. As is clear from the above description, if the rotating body to which the scale is connected is engaged with the gear provided on the non-rotating member of the head and a spring force is applied to the gear,
The pressure load due to the spring force between the rotating body and the multiple shafts can be reduced. However, if the diameter of the gear of the rotating body 4 is small, the force F that acts on the rotating body 4 in the balancing direction must be increased. When the above F becomes large, this F causes the rotating body 4 to
The frictional force between the In order to reduce the above F, it is necessary to make the diameter of the rotating body 4 as large as possible. However, since the gear 9 must rotate at the same time as the rotating body 4, the larger the diameter of the rotating body 4 is, the larger the diameter of the gear 9 must be, and the storage space for the gear 9 becomes larger. Put it away. The purpose of the present invention is to provide a scale balance device that solves the above problems.
A two-stage intermediate gear is interposed between the rotating body 4 and the gear 8, so that the diameter of the rotating body can be increased without increasing the diameter of the gear. The configuration of the present invention will be described in detail below based on embodiments shown in the accompanying drawings. In FIG. 1, reference numeral 10 denotes a drawing board, which is fixed to a support frame of a drafting table which is tiltable so that a desired angle of inclination can be fixed between horizontal and vertical. 12 is a horizontal rail arranged on the upper side of the drawing board 10, and a horizontal cursor 14 is movably attached to this rail. The horizontal cursor 14 has a vertical rail 16
are connected at the top. The lower end of the vertical rail 16 is movably placed on the drawing board 10 via a tail roller. A vertical cursor 18 is movably attached to the vertical rail 16, and a support substrate 24 of the head 22 is connected to this via a known double hinge mechanism 20. In FIG. 2, reference numeral 26 denotes a tubular double shaft rotatably supported by the support substrate 24, and a tubular spacer 28 and a protractor 30 are fixed to the flange of the double shaft 26 with screws. The protractor board 30 is a baseline brake (not shown)
It is releasably fixed to the support substrate 24 by. 32 is a main shaft, and its outer peripheral surface is rotatably fitted to the inner peripheral surface of the compound shaft 26. A handle 34 is fixed to the upper part of the main shaft 32,
A scale mounting plate 38 is fixed to the lower part of the main shaft 32 via a spacer 36. Scales 40 and 42 are fixed to the scale mounting plate 38. A first gear 44 is formed on the scale mounting plate 38 over a range of approximately 240 degrees around the rotation center of the main shaft 32. 46 is the second
The gear 46 is connected to a disk 50 that is rotatably supported by a shaft 48 on the support substrate 24. A rope 52 is connected between the disk 50 and the gear 46.
A space for arranging the is formed over a predetermined range. A threaded shaft 54 is installed in the bracket formed on the gear 46 in the diametrical direction of the gear 46, and a molding 56 is screwed onto the threaded shaft 54. A bridge member 58 is rotatably fitted into the recessed portion of the molding 56. The bridge member 58 is a gear 46
is regulated by a guide along the screw shaft 54,
It is configured to move in conjunction with the movement of the molding 56 along the screw shaft 54. The bridge member 58 has a metal terminal 5 connected to one end of the rope 52.
2a is fitted. Reference numeral 60 denotes a guide pulley that is rotatably supported by the support substrate 24, and the rope 52 is hung on the guide pulley. The other end of the rope 52 is connected to one end of a spring 62, and the other end of the spring 62 is engaged with a screw fixed to the support substrate 24. 64 is a shaft fixed to the support substrate 24, and an intermediate gear 66 consisting of a two-stage gear is rotatably supported on this. The small diameter gear 66a of the intermediate gear 66 meshes with the second gear 46, and the large diameter gear meshes with the first gear 44. In this embodiment, if the diameter of the first gear 44 is A, the diameter of the large diameter gear 66b is B, the diameter of the second gear 46 is C, and the diameter of the small diameter gear 66a is D, then A:B
=C:D is set. Next, the operation of this embodiment will be explained. When the fixation of the scale mounting plate 38 to the support substrate 24 is released and the scale mounting plate 38 is in a free rotating state, if the drawing board 10 is tilted, the scale mounting plate 38 will be rotated on multiple axes due to the weight of the scales 40, 42, etc. 26, a rotational torque E is generated in the counterclockwise direction of rotation of the hour hand in a plane parallel to the surface of the drawing board 10 in FIG. On the other hand, due to the tensile elasticity of the spring 62, a rotational torque F is generated in the second gear 46 in the direction of rotation of the hour hand in FIG.
is transmitted to the first gear 44 via the intermediate gear 66 as a torque in the direction of rotation of the hour hand. The rotational torque due to the weight of the scales 40, 42, etc. of the first gear 44 and the rotational torque due to the spring 62 are in opposite directions, so they cancel each other out. Then,
It does not suddenly rotate relative to the support substrate 24 and maintains a stationary and stable state. As described above, the ratio A:B between the diameter A of the first gear 44 and the diameter B of the large diameter gear 66b is the same as the diameter C of the second gear 46 and the diameter B of the small diameter gear 66b.
6a and the diameter D is the same as C:D, the rotational angular displacement of the first gear 44 and the rotational angular displacement of the second gear 46 are the same, and the rotational angular displacement of the first gear 44 and the second gear 46 are the same. The sine curve of the rotational torque due to the weight of the scales 40, 42, etc. of the gear 44 of No. 1, and the spring 6
2, the sine curve of the rotational torque accompanying the rotation of the second gear 46 is synchronized. If two-stage gear 6
In order to synchronize the sine curve of the rotational torque due to the spring 46 of the second gear with the sine curve of the rotational torque due to the weight of the scales 40, 42, etc. of the first gear 44 without providing the second gear 46, must be the same as the diameter of the first gear 44. In this case, if the diameter of the first gear 44 is increased, the diameter of the second gear 46 must also be increased accordingly. When the first gear 44 is made small in diameter,
Since the radius required for the rotational torque of the gear 44 becomes smaller, it is necessary to increase the balance rotational torque of the gear that meshes with the first gear 44. As shown in FIG. 3, the balancing force F acting on the first gear 44 acts as a reaction force G on the gear 44, and the resultant force J of this reaction force G and the force H due to the weight of the scale mounting plate 38, etc. It acts between the double shaft 26 and the main shaft 32 as a result. This resultant force J acts as a frictional force between the main shaft 32 and the compound shaft 26. In order to reduce the resultant force J, the diameter of the first gear 44 must be increased. If the diameter of the gear 44 is large, the rotational torque of the gear 44 due to the balance force F acting on the gear 44 can be increased. Therefore, with a small balancing force F, the scale 40 of the first gear 44,
It is possible to generate a rotational torque in the first gear 44 that balances the rotational torque due to the weight of the gear 42 and the like. If the tensile force of the spring 62 is F1, the radius of the first gear 44 is R1, and the radius of the second gear 46 is R2, then R1×F=R2×F1 Since R2<R1, F<F1. That is, the spring 62 becomes a strong spring, and the amount of displacement thereof is reduced, so that the durability of the spring 62 is improved. The value of the load W applied to the center of gravity on the scale mounting plate 28 side due to the weight of the scales 30, 32 changes as the inclination angle of the drawing board 10 changes. Therefore, when the inclination angle of the drawing plate 10 is changed, the amount of eccentricity of the rope 52 with respect to the gear 46 is adjusted by adjusting the rotation of the molding 56, and the rotational torque of the second gear 46 in the balance direction is adjusted. Adjust the size. In FIG. 3, the coil spring 62 and the rope 52 have one end connected to the non-rotating portion of the head 22 and the other end connected to the eccentric portion of the second gear 46. The spring means is configured to apply a rotational torque that changes approximately in a sine curve as the rotation changes. Since the present invention is configured as described above, it has the effect of being able to achieve the object stated at the beginning.

[Brief explanation of the drawing]

1 is a plan view, FIG. 2 is a sectional view, FIG. 3 is a bottom view, and FIG. 4 is an explanatory view. 2...Scale, 4...Rotating body, 6...Spring,
10...Drawing board, 12...Horizontal rail, 14...Horizontal cursor, 16...Vertical rail, 18...Vertical cursor, 22...Head, 24...Support board, 26...
...double axis, 28...spacer, 30...protractor,
32...Main shaft, 34...Handle, 36...Spacer, 38...Scale mounting plate, 40, 42...
...Scale, 44...First gear, 46...Second
gear, 50... board, 52... rope, 54...
Screw shaft, 56... Molding, 58... Bridge member, 60
... Guide pulley, 62 ... Spring, 64 ... Shaft, 66 ... Two-stage intermediate gear.

Claims (1)

[Claims] 1 a head 22, a main shaft 32 rotatably supported on the non-rotating member side of the head 22, and a main shaft 32;
a scale mounting plate 38 fixed to the lower part of the main shaft 32, a handle 34 fixed to the upper part of the main shaft 32, and a scale 4 mounted to the scale mounting plate 38.
0.42, a first gear 44 is provided integrally with the main shaft 32 with its center aligned with the rotation center of the main shaft 32;
a second gear 46 rotatably supported on the non-rotating member side of the head 22;
The other end is connected to the non-rotating part side of the second gear 46.
The small diameter gear 66a and the large diameter gear 66b are coaxially formed, and the small diameter gear 66a and the large diameter gear 66b are formed coaxially. Gear 66a
meshes with the second gear 46 and the large diameter gear 6
6b meshes with the first gear 44 so that the rotational torque of the second gear 46 is transmitted to the first gear 44 in a direction that offsets the rotational torque due to the weight of the scales 40, 42, etc. a two-stage intermediate gear 66 rotatably supported on the non-rotating portion side of the head 22;
The first gear 44 and the second gear 46 are set such that the diameter ratio between the large diameter gear 66b and the second gear 46 and the small diameter gear 66a are substantially the same.
A scale balance device characterized in that the scales rotate in synchronization.