JPH0120996B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a drafting head equipped with a device for electronically reading the rotation angle of the drafting head, which is smaller than the unit angle scale marked on the protractor, and displaying the angle. The present invention relates to an encoding disk mounting device.

Recently, drawing heads used for manual drawing work on drawing boards have also been equipped with devices that electronically read the rotation angle of the drawing head and display the rotation angle. This device incorporates an optical encoding disk for converting the amount of rotation of the drawing head into a periodic sinusoidal electrical signal. This optical encoding disk must be fixed to the aluminum alloy protractor while maintaining its flatness with high accuracy, and must be fixed to the aluminum alloy protractor to maintain its flatness with high precision. Since it must withstand severe temperature changes, it is made of a synthetic resin film, and the encoding disk made of this synthetic resin film is fixed to the lower surface of the dial using screws and adhesive. Encoding disks made of the materials listed above will not be damaged even when the protractor expands or contracts due to temperature changes, but synthetic resin films may suffer from a decrease in flatness accuracy due to bending, etc. There is a big drawback.

Therefore, in order to avoid the above-mentioned drawbacks, if the encoding disk is made of glass material, there will be a large difference between the thermal expansion coefficient of the aluminum alloy material that is the material of the dial and the thermal expansion coefficient of the glass material. Therefore, there are major difficulties in the method of combining them.

SUMMARY OF THE INVENTION An object of the present invention is to provide an encoding disk mounting device for a drafting head in which the glass encoding disk does not break even when sudden temperature changes occur. To achieve this objective, the present invention has a protractor with an angular scale and a straightedge that is selectively integrated with a handle shaft that stands perpendicular to the drawing board and is rotatable. , and has a drafting head board fixed to the lower end of the handle shaft, an angle detector fixed to the drafting head board, and an encoding disk mounted in a fixed positional relationship with respect to the protractor. In the one incorporated in the drafting head, the encoding disk is formed in an annular shape from a glass material, and a disk mounting ring made of a stainless steel material is arranged inside the annular encoding disk, The feature is that the inner diameter surface of the encoding disk and the outer diameter surface of the disk attachment ring are bonded at several points on the circumference, and the disk attachment ring is screwed onto the protractor. shall be.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to FIGS. 1 to 3. FIG. 1 shows a longitudinal section of an encoding disk mounting device 1 for a drafting head, which is an embodiment of the invention. The drawing head 2 is connected to a vertical rail (not shown) that is movable in the left-right direction on the drawing board along a horizontal rail attached to the upper edge of the drawing board (not shown) by a connecting member (not shown) equipped with a hinge mechanism. There is. This drawing head 2 is movable on the drawing board along a vertical rail. At the center of the drafting head 2, a cylindrical handle shaft 3 stands perpendicular to the drafting board.
A knob (not shown) is fixed to the upper end of the holder. This knob allows the operator to translate the entire drawing head 2 on the drawing board or to rotate the handle shaft 3. An outward flange 4 is formed at the lower end portion of the handle shaft 3, and this outward flange 4
A drafting head board 5 is disposed in contact with the lower surface of the drawing head board 5, and this drafting head board 5 is screwed onto the outward flange 4 with screws 6. This drafting head board 5 is formed with a ruler attachment part 7 for attaching a straightedge (not shown), and an angle detector 8.
An angle detector support plate 9 is fixed to the tip thereof.

Furthermore, a ratchet wheel operating plate 10 is disposed on the drafting head base plate 5 and is capable of sliding in a straight line relative to the drafting head base plate 5.

The handle shaft 3 is fitted into a non-rotatable bearing 11 so as to be rotatable. This bearing metal 11 is supported by the above-mentioned connecting member in an unrotatable state. Thick outward flanges 12 and 13 are formed at the upper and lower ends of the bearing metal 11. The bearing metal 11 is connected to the connecting member at the upper outward flange 12, and an annular fixed plate 15 for fixing the protractor plate 14 is attached to the lower outward flange 13.
is fixed with screws 16.

An aluminum alloy protractor 14 is disposed on the lower surface of the stationary plate 15, with almost all of its upper surface slidingly in contact with each other. The thermal expansion coefficient of this aluminum alloy is approximately 23.5×10 ^-6 .

The protractor board 14 is provided with a 360° standard minute scale with a unit angle scale of 1°. When the ratchet wheel 17 comes into contact with the lower surface of the protractor 14, the screw 1
It is fixed to the protractor board 14 by 7a. By engaging and disengaging the claw member 18 provided at the tip of the ratchet wheel operation plate 10 with the ratchet wheel 17, the relative rotation between the protractor board 14 and the drafting head board 5 is enabled or disabled. Become.

An annular groove 19 having a dovetail-shaped cross section is formed on the upper surface of the inner diameter side of the protractor 14, and a nut 21 in a fixed relationship with the protractor fixing lever 20 is screwed into the annular groove 19. The enlarged diameter head 23 of the matching bolt 22 is assembled. Since the bolt 22 is held in place by the fixed platen 15, when the protractor plate 14 rotates, the groove wall surface of the annular groove 19 comes into sliding contact with the enlarged diameter head 23 of the bolt 22.

A ring mounting groove 24 having a rectangular cross section, opening downward, and an annular overall shape is formed on the lower surface side of the protractor 14 and near the outer periphery. A disk mounting ring 25 is arranged in this ring mounting groove 24 . The disk mounting ring 25 is made of stainless steel, which has a thermal expansion coefficient (=9.9 to 10.5×10 ⁻⁶ ) close to the thermal expansion coefficient (=9×10 ⁻⁶ ) of the glass material constituting the encoding disk 26. It is configured. The inner diameter surface 25a of the disk mounting ring 25 contacts the inner diameter side groove wall surface 19a of the ring mounting groove 24, and the upper surface 25b of the disk mounting ring 25 contacts the groove upper wall surface 19b of the ring mounting groove 24. The outer diameter surface 25c is the outer diameter side groove wall surface 1 of the ring mounting groove 24.
It is a little far from 9c. Further, the disk mounting ring 25 is screwed onto the protractor 14 by a plurality of screws 25a' screwed together in the direction of its longitudinal axis.

The encoding disk 26 is fitted onto the disk attachment ring 25, and the inner diameter surface 26a of the encoding disk 26 and the outer diameter surface 2 of the disk attachment ring 25 are connected to each other.
5c, adhesive A is filled in spots at a plurality of places, and the disk attachment ring 25 and the encoding disk 26 are joined by this adhesive. The upper surface 2 on the inner diameter side of this encoding disk 26
6b comes into contact with the lower outer peripheral edge 14a of the protractor 14, thereby maintaining the levelness of the entire encoding disk 26.

As shown in FIG. 2, this encoding disk 26 has a large number of transparent slits 27 formed at its outer periphery with an angular pitch of 1 degree.
Opaque portions 28 adjacent to these slits 27
is formed by depositing chromium on a glass surface. A semicircular annular opaque portion 29 is formed by vapor deposition of chromium in a portion that corresponds to the inner circumferential side of the many slits 27. Many slits 27
Alternatively, the opaque portion 28 is an optical pattern for reading angles in units of minutes smaller than the unit angle scale of the protractor 14, and the semicircular opaque portion 29 is an optical pattern for reading the rotational direction of the drafting head board 5. be. An angle detector 8 rotates integrally with the drafting head board 5 above and below these optical patterns. In the above embodiments, stainless steel was used as the material for the disk mounting ring, but the material may have a temperature expansion coefficient in the range of 8.0 x 10 ^-6 to 13 x 10 ^-6 . It is possible to use any material found in . Materials that fall under this category include, for example, cast iron (temperature expansion coefficient
10.6×10 ^-6 ), platinum (9.0×10 ^-6 ), wrought iron (same
12.6×10 ^-6 ), nickel (12.6×10 ^-6 ), steel (11.0×10 ^-6 to 12.0×10 ^{-6 )} , etc.

As described above, according to the encoding disk mounting device according to the above embodiment, a disk attachment ring made of stainless steel or the like having a temperature expansion coefficient close to that of a glass encoding disk is attached to the encoding disk. Since the disk attachment ring is attached with adhesive and screwed onto the protractor, the encoding disk will not break even if there is a sudden change in temperature.

In addition, since the encoding disk and the disk mounting ring are jointed in spots with adhesive, the difference in expansion or contraction due to the difference in temperature expansion coefficient between glass and stainless steel materials can be absorbed by the encoding disk. The cracking resistance of the encoding disk is further improved by adjusting the clearance between the inner diameter side of the disc and the outer diameter side of the disk mounting ring.

Next, another embodiment of the present invention will be described based on FIG. In this embodiment, an outward flange 31 is formed at the upper end of a stainless steel disk attachment ring 30, and a glass encoding disk 32 is formed on the lower surface side 31a of this outward flange 31.
With the upper surface side 32a in contact, the encoding disk 32 is externally inserted into the disk attachment ring 30 with a slight clearance, and the inner diameter surface 32b of the encoding disk 32 and the disk attachment ring 3 are fitted.
The outer diameter surface 30a of 0 is joined in spots with the adhesive 33. The outward flange 31 accurately maintains the flatness of the encoding disk 32 and prevents the adhesive 33 from leaking to the lower surface of the protractor disk 34. Therefore, after screwing the disk attachment ring 30 onto the protractor 34, the encoding disk 32 is attached.
This can be easily done even when the encoding disk 32 is placed coaxially with respect to the protractor 34, and then the encoding disk 32 is bonded to the disk attachment ring 30 using a sol-like adhesive.

The upper surface side 31b of the outward flange 31 is a protractor 34
Groove upper wall surface 3 of the annular groove 35 formed on the lower surface side of
5a. Further, the intermediate diameter annular portion 36 of the encoding disk 32 abuts against the lower outer peripheral edge portion 37 of the protractor 34 .

The disk attachment ring 30 is screwed onto the protractor plate 34 with screws 38.

As described above, according to the present invention, the glass encoding disk does not break even if a sudden temperature change occurs, and since it is made of glass, the flatness of the optical pattern can be maintained with high precision. can.

[Brief explanation of drawings]

FIG. 1 is a main longitudinal cross-sectional view of a drafting head having an encoding disk mounting device according to the present invention, FIG. 2 is a plan view of a joint structure between an encoding disk and a disk attachment ring, and FIG. FIG. 7 is a longitudinal cross-sectional view of an encoding disk mounting device according to another embodiment of the invention. 1... Drafting head encoding disk mounting device, 2... Drafting head, 3... Handle shaft, 5...
... Drafting head board, 8 ... Angle detector, 14 ...
Protractor board, 25...Disk mounting ring, 25
a'...Biss, 26...Encoding disk, 26a
...Inner diameter surface, A...Adhesive.

Claims (1)

[Claims] 1. A protractor with an angular scale and a straightedge, which are selectively integrated into a handle shaft that stands perpendicular to the drawing board and is freely rotatable, are attached and fixed at the lower end of the handle shaft. The above-mentioned drafting head is incorporated in a drafting head having a drafting head board, an angle detector fixed to the drafting head board, and an encoding disk mounted in a fixed positional relationship with respect to the protractor. The encoding disk is formed into an annular shape made of glass material, and a disk attachment ring made of stainless steel is placed inside the annular encoding disk, and the disk is attached to the inner diameter surface of the encoding disk. This is a drawing head encoding disk mounting device in which the disk mounting ring is bonded to the outer diameter surface of the drawing head at several points on the circumference, and the disk mounting ring is screwed onto the protractor.