JPH0667680B2 - Scale balance device for universal parallel ruler - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scale balance device for balancing the rotational force due to the weight of the scale in a universal parallel ruler.

2. Description of the Related Art As conventional devices, there are Japanese Utility Model Publication No. 52-28605 and Japanese Utility Model Publication 59
The devices described in Japanese Patent Laid-Open No. 131893 and Japanese Patent Laid-Open No. 61-104898 are known.

In the device of Japanese Utility Model Publication No. 52-28605, a cam member, which rotates integrally with the scale, is brought into contact with a driven member as a braking device via a spring elastic force to balance the rotational force due to the weight of the scale.

The device of Japanese Utility Model Laid-Open No. 59-131893 balances the rotating force due to the weight of the scale by winding a rope with tension elastic force around a rotating member that rotates together with the scale.

In the device disclosed in Japanese Patent Laid-Open No. 61-104898, a rotating body having an axis different from the axis of rotation of the scale is interlocked with the scale, and a spring elastic force is applied to the rotating body so that the scale is driven by its own weight. It balances the rotational force.

Problems to be Solved by the Invention In this type of scale balance device, when the drawing board to which the universal parallel ruler is attached is inclined, the rotational force due to its own weight becomes zero when the scale faces directly above and below, Whether or not the rotational force gradually increases as it rotates from directly above to the horizontal direction, reaches its maximum at the horizontal position, and gradually decreases as it rotates from the horizontal direction to just below, providing a smooth balance. Is a problem.

In the device of Japanese Utility Model Publication No. 52-28605, since a driven member of a cam member that rotates integrally with the scale is brought into contact with the scale member as a braking device via spring elasticity, smooth braking is difficult and the scale rotation operation becomes heavy. There is the actual development Sho 59-1318
The device of No. 93 wraps a rope with tension spring elasticity around a rotating member that rotates integrally with the scale, and pulls the rope as it rotates, so it is good when the scale rotates horizontally from directly above, Since the tensile force continues to increase from the horizontal direction to the position just below, there is a problem that it becomes difficult to balance the rotational force due to the weight of the scale.
The device of the 4898 gazette rotates a rotary body that has an axis center at a position different from the rotary shaft of the scale in conjunction with the scale, and applies a spring elastic force to this rotary body to rotate the scale by its own weight. However, there is a problem in that the device is complicated and the interlocking device is burdened because the device is balanced.

SUMMARY OF THE INVENTION Therefore, according to the present invention, a winding member and a cam member are provided on a rotating member of a scale operating head portion that rotates integrally with a scale, and a pulling member is provided on the winding pulley so that the winding member can be wound. At the same time, the cam member is provided with a follower member which is movably engaged at one end side thereof and is movable along the longitudinal direction according to the cam shape, while the non-rotating member is provided with a balance rod swingably about a fulcrum shaft. The other end side of the tension member and the other end side of the driven member are connected to both sides of the balance rod with a fulcrum shaft in between, respectively, to give tension spring elasticity to the tension member or the driven member, and the self-weight of the rotation angle of the scale. The present invention provides a scale balance device for a universal parallel ruler that balances the rotational force of the.

When the working scale rotates horizontally from directly above, the tension member is retracted according to the rotation of the take-up pulley, and the spring elastic force proportional to the retracted amount is applied to the rotation member, and the rotation force due to the weight of the scale is applied. When the scale is balanced against each other and rotates from the horizontal direction to the position directly below, the pulling amount of the tension member increases, but the cam member causes the driven member to exceed the pulling amount of the tension member via the balance rod and pulling direction. To gradually reduce the spring resilience acting on the tension member to counterbalance and counterbalance the rotational force due to the scale's own weight.

EXAMPLE The apparatus of the present invention will be described in detail with reference to the following examples. Reference numeral 1 is a bearing base of a scale operating head unit connected to a cursor or a pulley base that moves in parallel along the plane of the drawing board. It constitutes a non-rotating member, and its bearing portion rotatably supports the hollow shaft rod 2. A rotating member 3 according to the present invention is integrally fixed to the upper part of the shaft rod 2 with screws, and a scale support base 4 is integrally fixed to the lower part with screws. A handle 5 for operating the scale is integrally fixed to the upper part of the rotating member 3, while a scale mounting plate 6 is fixed to the tip of the scale support base 4, and the scale mounting plate 6 at the lower part is fixed by the handle 5. It is configured so that the scale attached to can be rotated. Further, a graduation plate 7 that can be fixed to the bearing base 1 at any time by a fixing lever 8 is rotatably attached to the bearing portion and faces a vernier plate 9 fixed to the scale support base 4 side. The scale fixing plate 10 and the indexing plate 11 are integrally fixed to the protractor 7, and the scale fixing plate 10 can be fixed to the scale support base 4 at any time by a scale fixing lever not shown in the figure. The plate 11 is configured to be fixed to the scale support base 4 by engaging indexing claws 12 in grooves at predetermined angles. The indexing claw 12 includes an interlocking piece 13 and an axle rod 2 that interlock with each other along the lower surface of the scale support base 4.
And a lever rod 14 penetrating into the hollow portion of the rotating member 3,
And a lever 15 provided on a side portion of the handle 5 are interlocked with each other, and are provided on the indexing plate 11 so that they can be engaged and disengaged. 16, 17
Is a cover body that rotates integrally with the scale mounting plate 6, and a loupe 18 is provided at a portion facing the vernier plate 9. 19
Is a scale mounting screw.

Here, the rotating member 3 according to the present invention is provided with a winding pulley 20 having a substantially circular arc shape, and a cam member 21 having a concave groove shape integrally provided downward. One end of a tension member 22 is attached to the winding pulley 20 so that the tension member 22 can be wound, and the other end of the tension member 20 is attached to one side of a balance rod 24 through a tension spring 23 so that its length can be adjusted. There is. In the case of the embodiment, the balance rod 24 is screwed with a hollow outer screw-shaped adjusting rod 26 so as to be able to move forward and backward, and a pulling rod 27 that is integrally moved forward and backward with the adjusting rod 26 and is rotatably fitted in the hollow portion. It is provided and the other end of the tension member 22 is attached. The balance rod 24 has an intermediate portion swingably provided on a fulcrum shaft 25 provided upright on the bearing base 1. The other end of the driven member 28 of the cam member 21 is swingably provided on the other end of the balance rod 24. In the case of the embodiment, the bearing 29 rotatably provided at the tip of the driven member 28 is engaged in the concave groove of the cam member 21, and the tension member 22 and the driven member 28 receive the tensile force of the tension spring 23. Are balanced. Reference numeral 30 is a guide member for guiding the driven member 28 so as to be swingable and movable in the longitudinal direction. Further, in the case of the embodiment, the tension member 22 is a spring elastic member that applies a tension force in the bending direction.
31 is provided. That is, a lever 33 that swings around a support shaft 32 erected on the bearing base 1 is provided, and a tension roller 34 at the tip of the lever 33 is rotatably abutted on one side of the tension member 22. Support shaft 35 standing on the bearing base 1 of the lever 33
A spring elastic member (31) stretched between and is pulled in the bending direction. Therefore, in this case, when the tensile force applied to the tensile member 22 is weak, the tensile force of the spring elastic member 31 causes the tensile member 22 to bend, and when the tensile force increases, the tensile member 22 becomes linear, Depending on the strength of the pulling force applied from the winding pulley 20 to the tension member 22,
The amount of movement of 22 in the winding direction can be adjusted.

As shown in FIG. 5 to FIG. 7, the take-up pulley 20 and the cam member 21 are moved along with the rotation of the scale (scale mounting plate 6) from a position right above to a position right below via a horizontal position.
Since it rotates 0 °, at a minimum, this 180 ° configuration is sufficient. In the case of the embodiment, first, the winding pulley 20 is
In the figure, the cam member 2 has a 180 ° semi-circular arc shape of ABC.
1 indicates that the 90 ° portion between B and C is 1/4 circular arc, C-
The 90 ° part between D is formed in an oval shape with a gradually increasing radius of gyration. Therefore, in this case, when shifting from FIG. 5 in which the scale is rotated from directly above to FIG.
The tension member 22 is wound along the circular arc of the winding pulley 20, receives the tensile force of the tension spring 23 and the spring elastic member 31 in proportion to the winding amount, and balances by canceling the rotational force due to the weight of the scale. It will be. Also, at this time,
Since the cam member 211 has a constant radius of rotation, the balance rod 24 is kept stationary. Next, when the scale rotates from the horizontal position to the position right below and shifts from FIG. 6 to FIG. 7, the tension member 22 is further wound by the arc extending from B to C of the winding pulley 20. Since the member 21 shifts the driven member 28 from right to left in the figure along the shape in which the radius of rotation gradually increases from C to D, the balance rod 24 includes the tension member 22 with the fulcrum shaft 25 as the center. The end is fed in the winding direction, and the tensile force of the tension spring 23 is gradually weakened to balance the rotational force due to the weight of the scale. In this case, it is preferable to adjust the position of the fulcrum shaft 25 of the balance rod 24 so that the distance between the connecting portion with the driven member 28 and the distance between the connecting portion with the tension member 22 is approximately three times or more larger. In order to reduce the movement ratio of the tension member 22 to the movement amount of the driven member 28 by adjusting the position of the fulcrum shaft 25 of the balance rod 24, the shape of the take-up pulley 20 is changed as shown by the broken line in FIGS. 5 to 7. B from B to C
To C ', the radius of gyration is formed to be extremely small, and the winding amount of the tension member 22 from the horizontal position of the scale of FIG. 6 to the position where the scale of FIG. be able to. Further, with this configuration, the amount of increase in the radius of gyration of the cam member 21 between C and D can be reduced accordingly.

As described above, according to the present invention,
A winding pulley and a cam member are provided on a rotating member that rotates integrally with the scale, and a pulling member is provided on the winding pulley so that it can be wound. A non-rotating member is provided with a balance rod swingable about a fulcrum shaft, and the other end of the tension member and the other end of the driven member are provided on both sides of the balance rod. Since the fulcrum shafts are connected to each other, the tension spring elasticity is applied to the tension member or the driven member, and the rotation force due to the weight of the rotation angle of the scale is balanced, the scale is horizontal from directly above. When it is rotated toward, the tension member is retracted according to the rotation of the take-up pulley, and the spring elastic force proportional to the retracted amount is applied to the rotation member, and the scale is opposed to the rotational force due to the weight of the scale. When the balance member is rotated and rotated from the horizontal direction to the position directly below, the pulling amount of the tension member increases, but the cam member causes the driven member to move in the pulling direction beyond the pulling amount of the tension member through the balance rod. , Gradually reduce the spring resilience acting on the tension member,
The effect of providing a scale balance device that can balance against the rotational force due to the self-weight of the scale and that can operate reasonably smoothly without making a major design change to the scale operation head part of the conventional universal parallel ruler There is.

[Brief description of drawings]

FIG. 1 is a plan view showing an essential part of an embodiment of the device of the present invention, FIG. 2 is a cross-sectional view taken along the line AA ′ in FIG. 1, and FIG. 3 is shown in FIG. FIG. 4 is a vertical sectional view showing a main part of FIG. 1 in a vertical section, and FIGS. 5 to 7 show operating modes of the device of the present invention. It is a schematic explanatory drawing explaining. 1 …… Bearing base (non-rotating member) 2 …… Shaft rod 3 …… Rotating member 4 …… Scale support base 5 …… Handle 6 …… Scale mounting plate 20 …… Winding pulley 21 …… Cam member 22 …… Tension member 23 …… Tension spring 24 …… Balance rod 25 …… Support shaft 28 …… Follower member 31 …… Spring elastic member 33 …… Lever 34 …… Tension roller

Claims (4)

[Claims] 1. A winding member and a cam member are provided on a rotating member that rotates integrally with a scale, a pulling member is provided on the winding pulley so that the winding member can be wound, and one end of the cam member is engaged with the cam member so as to be driven. A driven member movable along the longitudinal direction according to the cam shape is provided, while a non-rotating member is provided with a balance rod capable of swinging about a fulcrum shaft, and the other end side of the tension member and the other end side of the driven member are provided. Scale balance in a free parallel ruler, which is formed by connecting fulcrum shafts on both sides of the balance rod, applying tension spring elasticity to the tension member or the driven member, and balancing the rotation force due to the weight of the rotation angle of the scale. apparatus 2. A scale balance device in a free parallel ruler according to claim 1, wherein the pulley and the cam member are formed in a shape corresponding to a rotational force due to the weight of the rotational angle of the scale. 3. A scale balance device in a universal parallel ruler according to claim 1 or 2, wherein tension spring elasticity is applied to the tension members. 4. Claims (1), (2) or (3)
The scale balance device in the universal parallel ruler, wherein the relative position between the fulcrum shaft and the balance rod is movable.