JPH0440B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a head bullet that, when the head is raised relative to the drawing surface, bounces the head in the upward direction so that the head does not fall suddenly even if the hand is released from the head at the raised position. The present invention relates to an elastic force adjustment device for a firing device.

In this type of device, it is desirable to maintain the head in a floating state when the head is raised or floated from the drawing surface, and to maintain this close contact state when the head is brought into close contact with the drawing surface. Conventionally, in this type of device, a spring 6 is elastically applied in the upward direction to a link 4 (see Fig. 1) that supports the head 2, and the elastic force of the spring 6 itself is changed to increase the elastic force of the link 2. By changing the rotational torque in the counterclockwise rotational direction about the rotation center 8, the elastic force that lifts the head 2 connected to the link 2 from the plane of the drawing board is adjusted.

The operating principle of this configuration will be explained below.

Incidentally, as shown in FIG. 2, since the rotation range, that is, the usage range of the link 4 is small, the radius a as a rotational torque generating element assumed to rotate the link 2 about its rotation center 8 is smaller than the radius a of the head 2.
Since there is almost no difference between when the head is in close contact with the drawing board and when it is floating from the drawing board, the explanation will be made assuming that the radius a1 when the head is in close contact with the drawing board and the radius a2 when the head is floating are equal.

If K is the spring constant of the spring 6 and S is its deflection, then the spring force F=K×S The torque T acting on the link 4 is Torque T=F×a=K×S×a This formula shows that the torque T is This shows that it is proportional to the amount of deflection S of the spring 6.

The relationship between torque T and spring deflection S is the fifth
This is as shown in the graph shown in the figure.

The following two conditions are required for a head firing device.

(1) When the head 2 is brought into close contact with the drawing board with the drawing board standing perpendicular to the floor surface, the rotational torque of the link 4 shall be zero.

(2) When the drawing board is horizontal to the floor, sufficient rotational torque exists in the link 4 to hold the head 2 in a position where it floats above the drawing surface.

From the above two conditions, when the drawing board is vertical, when the drawing board is tilted about 60 degrees, and when it is horizontal,
The usable range of the spring deflection S is as shown in FIG. As can be seen from FIG. 5, when the drawing board is vertical, the torque To of the link with the head in the floating state and in the close state is zero and the same. When the drawing board is inclined at about 60 degrees, the torque T2 of the link when the head is in close contact with the head is approximately twice the torque T1 of the link when the head is floating. When the drawing board is horizontal,
The torque T4 of the link when the head is in close contact is approximately 4/3 times the torque T3 of the link when the head is floating. That is, the magnification increases as the drawing board becomes more vertical. In the figure, A indicates a point that satisfies the above condition (1), and B indicates a point that satisfies the above condition (2).

As a result of the above, the following problems arise in the conventional device. The difference in link torque when the head is in close contact with the drawing surface and when it is floating is too large. or,
The link torque is greater when the head is in close contact with the drawing surface than when the head is floating. From the above, if the head is floated only by the link, the head will not come into close contact with the drawing surface due to its own weight, but if the head is set so that it comes into close contact due to its own weight, the head will not come into contact with the drawing surface due to the torque of the link. Can no longer float.

Further, the magnification of the torque when the head is in close contact with that when the head is floating differs depending on the inclination angle of the drawing board.
Therefore, although there is a possibility that the conventional device can be adapted to a specific drawing board inclination angle by applying a frictional force to the link, it is not possible to deal with other drawing board inclination angles.

The purpose of the present invention is to eliminate the above-mentioned conventional defects, and as shown in FIG. The structure is such that the elastic force applied to the head 2 can be adjusted by changing the distance. With this configuration, the following holds true: Spring force F=K×S Torque T=F×a=KSa. The relationship between the torque T and the deflection S of the spring 8 is as shown in FIG.
1 is the change characteristic of torque T with respect to deflection S when the drawing board is horizontal, L2 is the change characteristic of torque T when the drawing board is tilted at about 60 degrees, and L3 is the change characteristic of torque T when the drawing board is vertically erected. It is a changing characteristic. In the graph,
A indicates a point that satisfies the condition (1) above, and B indicates a point that satisfies the above condition (1).
The points that satisfy the condition (2) are shown, and the shaded area shows the usage range of the spring 6.

As is clear from the above graph, by using a spring with a small spring constant K, it is possible to reduce the difference in torque between when the head is in close contact with the head and when it is floating. However, in the conventional device, the spring constant K is determined from the above conditions (1) and (2). Also, the point that the link torque is greater when the head is in close contact than when the head is floating is different from the conventional device, but if the difference in torque between the head when it is floating and when it is in close contact can be reduced, it will be possible to have the head float and be in close contact. . Furthermore, by using a spring with a small spring constant K, it is possible to reduce the extent to which the magnification of the torque of the link when the head is floating relative to when the head is in close contact differs depending on the inclination angle of the drawing board. In order to reduce the difference in torque between the links when the heads are in close contact and when the heads are floating, the radius a should be made shorter when the heads are in close contact than when the heads are floating. This can be done by setting the fulcrum 12 of the spring 6 in the shaded area as shown in FIG. In the figure, a1 is the radius when the float is in close contact, and a2 is the radius when the head is floating. When this configuration is adopted, the relationship between the torque T of the link and the deflection S of the spring 6 is as shown in the graph of FIG. 7, and the curve L
1 is the characteristic of the torque T with respect to the spring deflection S when the drawing board is horizontal, L2 is the torque characteristic when the drawing board is tilted at 60 degrees, and L3 is the torque characteristic when the drawing board is set vertically.

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 freely so as to be fixed at a desired angle of inclination. 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. Reference numeral 12 denotes a vertical cursor movably attached to the vertical rail 8, and a support substrate 1 of the head 16 is connected to the vertical cursor via a known head lifting/lowering support device 14.
8 are connected.

A straight ruler 2 is mounted on the ruler mounting plate 20 of the head 16.
2 and 24 are attached. The head lifting/lowering support device 14 consists of links 26 and 28, and one side of the plate-shaped link 26 is rotatable in a plane perpendicular to the two planes of the drawing board by pivot shafts 30 and 32. Support member 1 fixed to the vertical cursor 12
It is pivotally supported by 2a. One end of the link 28 is rotatably supported by a shaft 34 on the support member 12a within a plane perpendicular to the two surfaces of the drawing board. The rising portion of the support substrate 18 is connected to the pivot shaft 30,
is rotatably connected to both sides of the other end of the link 26 by pivot shafts 36 and 38 parallel to 32;
The lower part of the support substrate 18 is connected to the link 28 by the shaft 41.
It is rotatably connected to the other end. Said link 2
6 and 28 constitute a known parallelogram link mechanism. 40 is a horizontal rail 4 on the upper plate of the link 26.
A recess 42 is a molding hole formed in the link 26, and a threaded rod 44 is disposed in the recess 40, and the tip of the threaded rod 44 is formed in the link 26. It is rotatably fitted into the hole 43. A molding 46 rotatably disposed within the hole 42 is fixed to one end of the threaded rod 44. Both side surfaces of the molding 46 are configured to slidably abut against the wall surface of the hole 42, and the threaded rod 44 is prevented from moving in its longitudinal direction by the wall surface of the hole 42. 48 is the recessed portion 40
This is a piece member disposed inside the body, and its screw hole is screwed into the threaded rod 44. Both side surfaces of the bridge member 48 are slidably in contact with the guide surfaces of the recessed portion 40 in a direction parallel to the horizontal rail 4, and the upper end surface of the bridge member 48 is slidably and resiliently contacted with the bottom surface of the recessed portion 40, This allows the bridge member 48 to connect to the threaded rod 44.
It is prevented from rotating in conjunction with the rotation of . 4
Reference numeral 9 denotes a cylinder whose lower end is supported by a shaft 51 on the wall surface of the notch of the support member 12a so as to be rotatable about an axis parallel to the plane of the drawing board 2, and is slidably disposed within the cylinder 49. The cylindrical rod 54 is urged by the elastic force of the coil spring 50 in a direction to protrude from the cylindrical body 49. The upper end protrusion of the rod 54 is rotatably fitted into a recess formed in the plate member 48.

Next, the operation of this embodiment will be explained.

When the handle 16a of the head 16 is grasped by hand and pulled up in the upward direction, the links 26 and 28 swing in the counterclockwise direction of rotation of the hour hand in FIG. 26,
The open end side of the head 28 rises relative to the two surfaces of the drawing board, and the head 16 rises while remaining substantially parallel to the two surfaces of the drawing board. When you release your hand from the handle 16a when the head 16 is in an arbitrary raised position, the weight of the head 16 causes a rotational torque T' to be applied to the link 26 in the direction of rotation of the hour hand in FIG. Occur. This rotational torque T' and the rotational torque T acting on the link 26 via the bridge member 48 due to the elasticity of the spring 50 are approximately the same in magnitude, and are opposite in direction. Therefore, head 1
6, when you let go of it, it will be almost balanced at any elevated position and will not fall due to its own weight. Incidentally, the elastic force of the rod 54 may be applied to the link 28 in the direction in which the head 16 floats.

Next, the operation of adjusting the distance between the center of rotation of the link 26 and the point of action of the spring 50 will be described.

When the molding 42 is rotated, the screw shaft 44 is rotated. As a result, the bridge member 48 moves along the guide surface of the recessed portion 40, and the other end of the rod 54 moves in the direction of the head on the link 26 in conjunction with the bridge member 48. By moving the piece member 48, the link 2
The distance between the center of rotation of 6 and the point of impact of the rod changes. Link 2 depending on the head's own weight etc.
The value of the load W applied to 6 changes as the inclination angle of the drawing board changes. Therefore,
When changing the inclination angle of drawing board 2,
2, the rotational torque T' generated on the link 26 by the load W is
The magnitude of the rotational torque T generated in the link 26 can be matched by the elastic force of the spring 50.

The cylindrical body 49, the rod 54, and the coil spring 50 constitute spring means for biasing the link 26 in the upward direction.

Since the present invention is configured as described above, the point of action of the spring means on the link can be changed with respect to the rotation center of the link, and the effect that this point of action can be prevented from shifting with respect to the link is achieved. exists.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram, Figure 2 is an explanatory diagram, Figure 3 is an explanatory diagram, Figure 4 is an explanatory diagram, Figure 5 is an explanatory diagram, Figure 6 is an explanatory diagram, Figure 7 is an explanatory diagram, 8 is an overall plan view, FIG. 9 is a cross-sectional view, FIG. 10 is a cross-sectional view taken along the line A-A, and FIG. 11 is a cross-sectional view taken along the line B-B. 2...Drawing board, 4...Horizontal rail, 8...Vertical rail, 12...Vertical cursor, 26...Link, 44
...Screw rod, 46...Mall, 50...Spring, 4
9... cylinder body, 54... rod.

Claims (1)

[Claims] 1. A horizontal rail 4 provided at the upper edge of the figure, a vertical rail 8 movably connected to the horizontal rail 4 at right angles, and a vertical cursor 12 movably attached to the vertical rail 8. A link 26 is pivotably supported on the vertical cursor 12 in a plane perpendicular to the drawing board 2, and a link 26 is connected to the open end side of the link 26 so as to move in conjunction with the movement of the link 26. Head 1
6, a screw rod 44 is rotatably supported on the link 26, a recess 40 is formed in the link 26 along the longitudinal direction of the screw rod 44, and a recess 40 is formed in the recess 40 along this. The bridge member 48 is arranged so as to be able to slide freely and not rotate,
While screwing the bridge member 48 to the screw rod 44,
one of the spring means for biasing the link 26 in the upward direction is rotatably connected to the vertical cursor 12;
The other of the spring means is rotatably connected to the bridge member 48, and the bridge member 48 is movable relative to the center of rotation of the link 26 by rotation of the screw rod 44. An elastic force adjustment device for a head elastic device in a parallel ruler.