JPH0432760B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a scale balancer for an arm type universal parallel ruler.

Conventionally, flexible parallel rulers that apply the principle of parallel movement of parallelograms have two types: an arm type in which a belt is stretched between pulleys placed at the end of the arm, such as this device, and a parallel ruler that uses links to There is a pantograph style that has a quadrilateral shape. When comparing the arm type and pantograph type, in order to achieve accuracy with the arm type, only the diameter of the pulley needs to be managed, and this pulley diameter can be easily improved with lathe work. However, the pantograph type is link 4.
High precision management of the positions of the pivot joints is required, and achieving this precision is difficult. In addition, in the pantograph type, parallel links are used until they become close to each other and the quadrilateral shape collapses, so when the shape of the links collapses, an error occurs in the accuracy of translation. The arm type is also superior in this respect. However, in terms of strength, the links of the pantograph type can be made as strong as desired, whereas the belt used for the arm type is moved by being hung on a pulley, so it must be made of a stretchable material.
This stretchable material will also stretch due to external stress. The elongation of the belt in the above-mentioned arm type appears when the arm type universal parallel ruler is used on a drawing board in an upright position.

This will be explained with reference to the explanatory diagrams of FIGS. 1 and 2.

When the head 4 is supported by hand to prevent it from falling downward while the drawing board 2 is in a substantially vertical position, the main shaft 6 of the head is held in a position where the weight of the scales 8, 10 and the scale mounting plate 12 causes the first In the figure, rotational torque is generated in the direction of rotation of the hour hand. This rotational torque is applied to the head pulley 1 via a known scale fixing mechanism such as an angle brake 14 or an index mechanism (not shown).
6. The head pulley 16 tends to rotate in the direction of rotation of the hour hand in FIG. 1 due to the rotational torque caused by the weight of the scales 8, 10, etc., and this rotational force is transmitted to the belt 20 between the intermediate pulley 18 and the head pulley 16. The belt 20 tends to rotate due to the torque of the pulley 16 in the direction of rotation of the hour hand in FIG. Intermediate pulley 18 is belt 2
2 to the fixed pulley 24 and is in a non-rotating state, one side 20a of the belt 20 receives pressure in the direction of extension, and the other side of the belt 20 receives pressure in the direction of contraction, and this pressure causes As a result, the belt 20 stretches. On the other hand, the intermediate pulley 18 is also rotated by the rotational torque of the head pulley 16.
As shown in the figure, the hour hand is trying to rotate in the direction of rotation. A base shaft 30 is fixed to a base 28 fixed to the drawing board 2 via a vise-type fixture 26, and a fixed pulley 24 is fixed to the base shaft 30. The fixed pulley 2
One side 22a of the belt 22 between 4 and the intermediate pulley 18
is subjected to pressure in an elongating direction by the rotational torque of the intermediate pulley 18, and the other side of the belt 22 is subjected to pressure in a contracting direction, causing the belt 22 to elongate. Due to the elongation of the belts 20, 22, the scales 8, 10 slightly move about the main shaft 6 in the direction of rotation of the hour hand in FIG. 1, resulting in an error in drawing accuracy.

If a weight type scale balancer is installed at the head of the arm type universal parallel ruler, the problem of belt elongation can be solved. That is,
A balance weight is attached to the opposite side of the scale mounting plate 12, and the weight of this balance weight 12 cancels out the rotational torque in the hour hand rotation direction in FIG. 1 due to the weight of the scales 8, 10, etc. applied to the main shaft 6. For example, when the head 4 is stationary, no rotational torque is generated in the head pulley 16, so the belt 2
The problem of elongation of 0.22 does not occur. However, this configuration has the disadvantage that the balance weight increases the weight of the head 4, and a large force is required to support the head 4 from falling by hand. Also, do not support head 4 with your hands.
If the head 4 is supported by a known weight type head balance device, the weight for supporting the head must be made heavier by the weight of the balance weight. A problem arises in that a large inertial force is generated when moving the head 4, making it difficult to operate the head 4. There are other scale balancers that use spring force to bias the scale mounting plate 12 in the opposite direction to the direction of rotation due to the weight of the scales 8 and 10, using the head pulley 16 as a fulcrum. , the rotational torque due to the weight of the scales 8 and 10 is transmitted to the head pulley 16 via the balance spring, and eventually the belt 2
The problem of elongation of 0.22 cannot be solved. However, as mentioned above, the arm-type flexible parallel ruler is superior in that it is easy to process the pulley with high precision, and the shape of the parallelogram does not collapse during operation. If the problem of belt elongation can be solved, it will be possible to provide an arm type universal parallel ruler that is superior to the pantograph type in all respects. SUMMARY OF THE INVENTION An object of the present invention is to provide an arm-type universal parallel ruler for elevation drawing boards that solves the problem of belt elongation.

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

In FIG. 3, reference numeral 30 denotes a drawing board, which is fixed to a support frame (not shown) of a drafting table so that it can be set at a desired angle with respect to the floor. 32 is drawing board 30
This is a vise-type fixture fixed to the upper edge of the board, to which a base 34 is rotatably pivoted about an axis 36 parallel to the surface of the drawing board 30. A reference shaft 38 is fixed to the base 34, and a fixed pulley 40 is fixed to this. A pulley cover 42 is rotatably fitted to the base shaft 38 via a ball bearing, and a first
One end of arm 44 is fixed. A cylindrical body 46 is rotatably fitted to the base shaft 38 via a ball bearing, the upper end flange of this cylindrical body is fixed to the pulley cover 42, and the lower end of the cylindrical body 46 is provided with an intermediate cylindrical body. A balance cam 48 is fixed. 50 is a cylindrical body rotatably fitted to the outer peripheral surface of the cylindrical body 46 via a ball bearing;
A rope pulley 52 is formed at the upper end of this, and a scale balance cam 5 is formed at the lower end of the cylinder 50.
4 is fixed. A cylindrical body 56 is rotatably fitted to the cylindrical body 50 via a ball bearing. A rope pulley 58 is formed at the upper end of this cylindrical body, and a head balance cam 60 is formed at the lower end of the cylindrical body 56. It is formed. 62 is the base 3
4, the intermediate portions of levers 64, 66, 68 are rotatably fitted onto the outer peripheral surface of this shaft, and the levers 64, 66, 68 are rotatably supported at one end thereof. Rollers 70, 72, 74 face the peripheral surfaces of the balance cams 60, 54, 48.
Reference numeral 76 denotes a spring adjustment screw that is slidably inserted into a bearing 78 fixed to the base cover 34. A threaded portion of the handle 80 is screwed into one end of the spring adjustment screw 76, and a plate member is attached to the other end of the screw 76. 82 is fixed. One end of each of the coil springs 84, 86, 88 is hooked to the U-shaped metal fitting fixed to the plate member 82, and the coil springs 84, 86,
Each other end of 88 is connected to each other end of the levers 66, 64, and 68. A pulley cover 90 is connected to the other end of the first arm 44, and a tube portion of the pulley cover 90 is rotatably fitted to the intermediate shaft 92 via a ball bearing. The intermediate shaft 92
A boss of an intermediate pulley 94 consisting of a double-type belt pulley is fixed to the holder, and an endless steel belt 96 is hung with an appropriate tension between the upper pulley portion of the intermediate pulley 94 and the fixed pulley 40. It has been passed. An idle pulley 98 is rotatably supported on the outer peripheral surface of the intermediate portion of the intermediate pulley 94 via a ball bearing.

The idle pulley 98 may be rotatably attached to the pulley cover 90. 100 is a second arm, and a lower pulley cover 102 is connected to one end of the second arm, and a tube portion of the cover 102 is rotatably fitted to the intermediate shaft 92 via a ball bearing. The pulley cover 102 includes a pulley 1
04 is formed, and a rope-like member 106 made of an endless head balancing wire rope is stretched between the pulley 104 and the pulley 58 with an appropriate tension. 110 is a head, and a tube body 114 is attached to the tube portion of the substrate 112 of this head.
is fixed, and the second arm 100 is fixed to the outer peripheral surface of the upper part of the tube body 114 via a ball bearing.
A tube portion of a pulley cover 116 connected to the other end is rotatably fitted. A head pulley 112a is formed on the substrate 112, and the pulley 112
An endless steel belt 118 is stretched between a and the intermediate pulley 94 with an appropriate tension. A main shaft 120 is rotatably fitted into the tube body 114, and a plate member 122 is fixed to the upper part of the main shaft 120. Said board member 1
A rope pulley 122a is formed on the outer periphery of 22. 124 is a handle of the head 110, which is fixed to the board member 122. A scale mounting plate 126 is fixed to the lower end of the main shaft 120, and a scale is removably fixed to the mounting plate 126. Reference numeral 132 denotes a protractor which is rotatably fitted into the tubular body 114, and is releasably fixed to the substrate 112 by a known baseline adjustment device. The scale mounting plate 126 can be releasably fixed to the protractor plate 132 at every 15 degrees by operating a known index mechanism using an index lever 136. Further, the scale mounting plate 126 can be releasably fixed to the protractor plate 132 at any angle by operating the angle fixing lever 140 using a known angle fixing device. The pulley 1
A rope-like member 142 made of an endless scale balancing wire rope is stretched between the pulleys 98 and 58 with an appropriate tension. , a rope-like member 144 made of an endless wire rope for scale balancing is strung around.

Next, the operation of this embodiment will be explained.

Grasp the handle 124 of the head 110 with your hand,
When the head 110 is moved along the surface of the drawing board 30, the substrate 112 of the head 110 is moved by the belts 118, 96.
A known translation guide mechanism consisting of pulleys 112a, 94, and 40 translates the drawing board 30 while maintaining a predetermined angle. If the scale mounting plate 126 is fixed to the substrate 112 using a known indexing mechanism, the scale will translate on the drawing board 30 while maintaining a predetermined angle. When the drawing board 30 is tilted in the upright direction and you release your hand from the handle 124 of the head 110, the first arm 44 will move under its own weight and the second arm 1
Due to the weight of the drawing board 30 and the weight of the head 110, etc., the drawing board 30 tries to rapidly rotate about the base shaft 38 along the inclination of the drawing board 30 in the falling direction. The rotational torque of the first arm 44 in the falling direction about the base shaft 38 is transmitted to the balance cam 48, and the balance cam 48 tends to rotate about the base shaft 38. On the other hand, a roller 74 comes into elastic contact with the cam surface of the balance cam 48 due to the tensile force of a coil spring 88, and the balance cam 48 has a rotational torque of approximately the same magnitude in the opposite direction to the falling direction of the first arm 44. Rotational torque for balance is generated. This balancing rotational torque cancels out the rotational torque in the falling direction due to the weight of the first arm 44 and the like applied to the balance cam 48, and the first arm 44 maintains a stationary state on the inclined drawing board 30. On the other hand, the second arm 100
depends on its own weight and the weight of the head 110,
It attempts to rapidly rotate around the intermediate shaft 92 in the falling direction. The rotational torque in the falling direction about the intermediate shaft 92 of the second arm 100 is transmitted to the head balancing cam 60 via the rope-like member 106. The roller 70 comes into elastic contact with the cam surface of the cam 60 due to the tensile force of the coil spring 86, and due to this elastic contact force and the shape of the cam 60,
A balancing rotational torque of approximately the same magnitude is generated in the cam 60 in the opposite direction to the rotational torque due to the weight of the head 110 and the like. This balancing rotational torque cancels out the rotational torque in the falling direction of the second arm due to the weight of the head 110 and the like applied to the balance cam 60, and the second arm 100 remains stationary on the inclined drawing board 30.

Next, when the fixation of the scale mounting plate 126 to the base plate 112 is released and the scale mounting plate 126 is allowed to rotate freely relative to the base plate 112, the weight of the scale and the weight of the scale mounting plate 126 cause the scale to Drawing board 3 centered on body 114
Trying to fall suddenly along 0. Rotational torque of the main shaft 120 connected to the scale due to the weight of the scale, etc. is transmitted to the plate member 122. Board member 122
The rotational torque in the scale falling direction is the rotational torque of the pulley 122.
a, rope-shaped member 142, idle pulley 98,
Rope-shaped member 144, pulley 52, and cylinder 5
0 and is transmitted to the scale balance cam 54. On the other hand, a rotational torque for scale balance is generated in the scale balance cam 54 due to the cam shape and the elastic contact force of the roller 72 due to the tensile force of the coil spring 84. The magnitude of the rotational torque for the scale is set to be approximately the same as the rotational torque applied to the cam 54 in the scale falling direction, depending on the weight of the scale, and the rotational torque applied to the cam 54 in the scale falling direction is set to be approximately the same as the rotational torque applied to the cam 54 in the scale falling direction. Since the directions of the balance rotation torques are set in opposite directions, they cancel each other out, and the cam 54 maintains a stationary state. Therefore, the scale has a slope of 30
Even if it is in a free rotation state with respect to the head substrate 112, it does not suddenly rotate in the falling direction and remains stationary. Therefore, the rotational torque of the main shaft 114 in the scale falling direction is hardly transmitted to the head pulley 112a, and therefore the belts 118, 96
The tensile force due to the rotational torque of the main shaft 114 is hardly applied to the main shaft 114.

As described above, the present invention transmits the rotational torque due to the weight of the scale of the head pulley to the pulley on the drawing board side through the rope-like member, and provides this pulley with a balancing rotational torque that offsets the rotational torque. This has the effect that rotational torque due to the weight of the scale, etc. is not transmitted to the belt, and elongation of the belt can be prevented.

[Brief explanation of drawings]

The drawings show preferred embodiments of the present invention; FIG. 1 is an explanatory view, FIG. 2 is an explanatory sectional view, FIG. 3 is a sectional view, and FIG. 4 is a plan view. 2...Drawing board, 4...Head, 6...Main shaft, 8,
10...Scale, 12...Scale mounting plate, 1
4... Angle brake, 16... Head pulley, 1
8... Intermediate pulley, 20... Belt, 22... Belt, 24... Fixed pulley, 26... Vise type fixture, 30... Drawing board, 32... Vise type fixture, 34
... Base cover, 36 ... Shaft, 38 ... Base shaft,
40...Fixed pulley, 42...Pulley cover, 4
4...First arm, 46...Cylinder, 48...Intermediate balance cam, 50...Cylinder, 52...Rope pulley, 54...Scale balance cam, 56
... Cylinder body, 58 ... Rope pulley, 60 ... Balance cam for head, 62 ... Shaft body, 64, 66,
68... Leverage, 70, 72, 74... Coro, 76
... Spring adjustment screw, 78 ... Bearing, 80 ... Handle, 82 ... Plate member, 84, 86, 88 ...
Coil spring, 90...Pulley cover, 92
...Intermediate shaft, 94...Intermediate pulley, 96...Steel belt, 98...Idle pulley, 102...
...Lower pulley cover, 104...Pulley, 106
... Rope-shaped member, 110 ... Head, 112 ...
...Substrate, 114...tube, 112a...pulley,
116...Pulley cover, 118...Belt, 1
20...Main shaft, 122...Plate member, 122a...
Rope pulley, 124... Handle, 126...
Scale mounting plate, 132... Protractor board, 136...
Index lever, 138... Index mechanism, 144... Rope-like member.

Claims (1)

[Claims] 1 A base shaft 38 fixed to a base 34 that can be fixed to a drawing board, and a fixed pulley 4 fixed to the base shaft 38
0, a first arm 44 whose one end is rotatably connected to the base shaft 38 and whose other end is rotatably connected to the intermediate shaft 92, and a pair of pulley parts fixed to the intermediate shaft 92. A pulley 94, a second arm 100 whose one end is rotatably connected to the intermediate shaft 92 and whose other end is rotatably connected to the tube 114 of the head 110, and a head pulley fixed to the tube 114 . 112a and the head pulley 11
2a and the intermediate pulley 94, an endless belt 96 stretched between the intermediate pulley 94 and the fixed pulley 40, and the tubular body 114 of the head 110. An arm type flexible parallel ruler consisting of a main shaft 120 that is rotatably supported and has a handle 124 fixed to its upper end and a scale mounting plate 126 fixed to its lower end, and a first pulley 12 on the main shaft 120 side.
2a is fixed, and the second
A pulley 52 is rotatably attached to the intermediate shaft 9.
An idle pulley 98 is provided rotatably about 2, and a rope-like member 14 is provided between the first pulley 122a and the idle pulley 98 and between the idle pulley 98 and the second pulley 52.
2,144, and the first pulley 12
2a and the second pulley 52 in the rotational direction,
The second pulley 52 is connected to the first pulley 12.
A scale balancer characterized in that a balance rotation torque is provided to offset the rotation torque due to the weight of the scale described in 2a.