JPS5844201B2 - Angle measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an angle measuring device, in particular a telescope holder for holding a reference telescope so as to be rotatable about the vertical axis of the machine, and a device for reading the rotation angle of this holder. The present invention relates to an angle measuring device having a scale.

An example of such an angle measuring device is a transit, but the present invention is not limited to such applications.

Conventionally, in this type of device, a rotating shaft provided in a fixed relationship with a telescope holder is fitted into a fixed shaft provided on a support base, and a conical support surface is formed at the upper end of the fixed shaft. By interposing a steel ball between the conical support surface and the holder support surface formed on the lower surface of the telescope holder, the telescope holder and the weight applied thereto are rotatably supported and the rotation axis is prevented from wobbling. For this purpose, the lower end of the rotating shaft is rotatably fitted into the fitting recess of the support base.

A scale plate having an angle scale is attached to the telescope holder concentrically with the rotation axis, and an index plate is provided opposite to the scale plate.

Of course, it is also possible to attach an indicator plate to the telescope holding part side and provide a scale plate opposite thereto, and in the present invention, the terms scale plate and indicator plate are used interchangeably in this way.

The index plate attached to the telescope holder is attached to a holder rotatably fitted around the outer periphery of the fixed shaft so that it can rotate independently of the rotation of the telescope holder.

In such conventional devices, in order to allow the telescope holder to rotate precisely and smoothly, the holder support surface that contacts the steel ball and the conical support surface on the fixed shaft are very hard. It is necessary to have a finished surface close to a mirror surface, and it is necessary to perform hardening treatment such as quenching on both the rotating shaft and fixed shaft, and then perform precision processing such as polishing or lamps.
Therefore, the processing cost becomes extremely high in terms of equipment costs, processing time, defect rate, etc.

Therefore, if it were possible to use standard type rolling bearings, such as angular contact ball bearings that can handle both radial and thrust loads, which are currently available in the market with high quality at low prices, it would be possible to significantly reduce processing costs. Become.

However, if the steel ball part in the conventional structure is replaced with an ordinary ball bearing and the telescope holder is supported on a fixed shaft by the ball bearing, the angle measurement error may become unacceptably large. , it becomes impractical.

In view of the above-mentioned circumstances, the present invention provides an angle measuring device having a structure in which angle measurement errors can be kept within an allowable range even when a general bearing for both thrust and radial loads is used.

That is, the angle measuring device according to the present invention includes a telescope holder that holds a reference telescope so as to be rotatable about the vertical axis of the machine, and a telescope holder that is provided concentrically with respect to the rotation center of the holder and that is In the type having a scale plate that rotates together with the scale plate, and an index plate that is provided opposite to the scale plate and can rotate around the rotation axis of the holding part, the holding part is rotated around the rotation axis of the holding part. The rotating shaft is fitted with the inner ring of the bearing for both thrust and radial loads, and a part of the outer ring of the bearing is connected to the mechanical support part concentrically to the rotational axis of the holding part. The indicator plate is fitted into a support recess provided in the support recess, and the indicator plate is rotatably fitted into the remaining part of the support recess.

In the conventional structure, the causes of angle measurement errors are (1)
Eccentricity error of the rotation axis, that is, runout due to ball transfer, (
ii) Eccentricity errors in the inner and outer diameters of the fixed shaft, and (iii) a gap between the inner diameter of the index plate holder and the fixed shaft. (ii) The value of each book can be reduced to about 1.5μ by precision processing.

Therefore, in the case of a 20 second reading transit with a scale plate diameter of 11071a, the total angle measurement error is approximately 12.7", which exceeds the allowable value of 10" according to the JIS standard.

In the structure of the present invention, since the indicator plate is supported by the outer ring of the bearing instead of the outer periphery of the fixed shaft, it is possible to completely eliminate the possibility that the error shown in (11) above will enter as an angle measurement error.
As a result, the total error can be greatly reduced, and even in a case corresponding to the above example, the error can be suppressed to γ tolerance using a commercially available bearing.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows an example in which the present invention is applied to a telescope, in which a telescope 1 is supported by a horizontal ear shaft 12 on a telescope holding member 2 so as to be rotatable within a vertical plane.

Below the holding member 2, a vertical rotation shaft 6 is provided in fixed relation, similar to conventional structures.

A vertical fixed shaft 5 is formed in the support base 11 of the machine, a rotating shaft 6 of the telescope holder is inserted into the fixed shaft 5, and a thrust and radial load is applied between the rotating shaft 6 and the fixed shaft 5. ball bearings 13 are arranged.

That is, the inner ring 14 of the bearing 13 is tightly fitted into the rotating shaft 6, and the outer ring 15 of the bearing 13 is fitted into a counterbore formed concentrically on the upper end surface of the fixed shaft 5.

The outer ring 15 may be bonded to the fixed shaft 5 if necessary.

In order to prevent the rotating shaft 6 from wobbling, the lower end of the rotating shaft 6 is rotatably fitted into a receiving hole 11a provided in the support base portion 11.

A receiver 9 is fitted onto the outer periphery of the outer ring 15 of the bearing 13, and a lower portion of the receiver 9 is rotatably fitted onto the outer periphery of the fixed shaft 5.

The receiver 9 has an indicator plate 8 at a position opposite to a scale plate 10 fixed to the telescope holder.

In the structure described above, the receiver 9 supporting the index plate 8
Since the radial position of the fixed shaft 5 is determined only by the bearing 13 fitted to the rotating shaft 6, eccentric errors in the inner and outer diameters of the fixed shaft 5 do not affect the angle measurement value.

Furthermore, in the above embodiment, it was explained that the outer ring of the bearing is glued to the fixed shaft as necessary, but a suitable lubricant, such as a self-lubricating Teflon sheet, etc., is applied between the outer ring of the bearing and the upper end surface of the fixed shaft. may be placed.

In this case, the receiver 9 and the outer ring 15 of the bearing may be in a fixed relationship.

[Brief explanation of drawings]

The drawing is a sectional view of a transit showing an embodiment of the present invention. 1... Telescope, 2... Holding part, 5...
...Fixed axis, 6...Rotating axis, 8...
・Indicator plate, 9...Bracket, 10...Scale plate, 13...Bearing, 14...Inner ring, 1
5... Outer ring.

Claims (1)

[Claims] 1. A reference telescope is held in such a way that the vertical axis of the machine can be centered. In the angle measuring device, the holding part has a scale plate that rotates together with the holding part, and an indicator plate that is provided opposite to the scale plate and can rotate around the rotation axis of the holding part. It has a rotating shaft that is concentric with the center, and this rotating shaft is fitted into the inner ring of a thrust and radial load bearing, and a part of the outer ring of the bearing is connected to a mechanical support stand concentrically with the rotating axis of the holding part. An angle measuring device, characterized in that the indicator plate is fitted into a support recess provided in the section, and the indicator plate is rotatably fitted into the remaining part. 2. The angle measuring device according to item 1, wherein a part of the rotating shaft of the holding part is rotatably fitted into a recess provided in the machine support part. 3. The angle measuring device according to item 1 or 2 above, wherein a commercially available bearing is used as the bearing. 4. The angle-side fixing device according to any one of Items 1 to 3 above, wherein the outer ring of the bearing is fixed to a support base. 5. The angle measuring device according to any one of items 1 to 3 above, characterized in that a lubricant is disposed between the outer ring of the bearing and the support base. 6. An angle measuring device according to claim 5, wherein the lubricant is a sheet of self-lubricating material.