JP4195147B2 - Center coordinate measurement target - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a center coordinate measurement target attached to a hole such as a bolt hole provided in a large structure that constitutes a bridge or the like in order to obtain the center coordinate of the hole.
[0002]
[Prior art]
In order to measure whether a large structure is created according to the design document, a target for central coordinate measurement is attached to a hole opened in the large structure, and the target for central coordinate measurement is measured by a distance measuring instrument. A method for obtaining the center coordinates of a hole and obtaining the shape of a large structure from the center coordinates of the hole is known. As a conventional center coordinate measurement target used in this method, for example, according to Japanese Patent Application Laid-Open No. 10-38573, a columnar insertion portion to be inserted into a hole established in a large structure is provided at the rear portion. There is known one having a retroreflective surface provided with an index located on the central axis of the front part.
[0003]
[Problems to be solved by the invention]
In the conventional center coordinate measurement target known from the above publication, when measuring with a ranging finder, the measurement is performed by aligning the crosshair on the ranging finder side with the index written on the retroreflective surface. Do. Therefore, the index of the retroreflective surface must be made coincident with the central axis of the hole. Since the index is located on the central axis of the insertion portion, the central axis of the insertion portion may be made to coincide with the central axis of the hole. Therefore, it is desirable that no gap is generated between the outer peripheral surface of the insertion portion and the inner peripheral surface of the hole. On the other hand, since the hole opened in the large structure is a bolt hole or a rivet hole, the diameter error may be relatively large, so that the variation of the diameter of the actually opened hole becomes large. In order to insert the insertion portion into any of the holes, the thickness of the insertion portion must be made thinner than the diameter of the smallest hole. However, when the insertion portion is made thinner in this way, a gap is formed between the inner peripheral surface of most holes and the outer peripheral surface of the insertion portion, and the center coordinate measurement target is in a state where the central axis of the insertion portion does not coincide with the central axis of the hole. Is attached to the hole. As a result, a measurement error occurs due to the deviation of the central axis.
[0004]
In view of the above problems, an object of the present invention is to provide a center coordinate measurement target that can make the center axis of the insertion portion coincide with the center axis of the hole even if the diameter of the hole varies.
[0005]
[Means for Solving the Problems]
In order to solve the above problems, the present invention has a retroreflective surface having an insertion portion inserted into a hole provided in a large structure at a rear portion and an index located on the central axis of the insertion portion. In the center coordinate measurement target provided in the portion, a synchronization member having a tapered portion formed at the tip in the insertion portion is provided so as to be urged forward by a spring, and is arranged at equal intervals in the circumferential direction of the insertion portion. At least three centripetal protrusions are provided, the tail end of the centripetal protrusion is inclined to contact the tapered portion of the synchronization member, and the distance between the center axis of the insertion portion and the tip is set to It is characterized by projecting from the outer peripheral surface of the insertion portion so as to be able to advance and retreat in synchronization with each other so as to be equal to each other, and an annular permanent magnet is provided on the back surface of the index.
[0006]
The tip of the centripetal protrusion protrudes from the outer peripheral surface of the insertion portion in synchronism so that the distance from the center axis of the insertion portion to the tip becomes equal to each other. The center of is located on the central axis of the insertion portion. Therefore, even if a gap is generated between the outer peripheral surface of the insertion portion and the inner peripheral surface of the hole, the centripetal protrusion protrudes and the tip of each centripetal protrusion abuts the inner peripheral surface of the hole. The central axis of the insertion portion coincides with the axis.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Referring to FIG. 1, reference numeral 1 denotes a center coordinate measurement target according to the present invention (hereinafter referred to as a target in the column of the embodiment of the present invention), which is a bolt hole formed at both ends of a bridge member B which is a large structure. Attached to each. Then, the coordinates of each target 1 are measured by the ranging finder M, and it is verified whether the bridge member B is processed as designed by using the coordinates of each target 1 as the bolt hole coordinates. The bridge member B is made of so-called H-shaped steel.
[0008]
With reference to FIGS. 2 and 3, a columnar insertion portion 2 whose tip is processed into a tapered shape is provided at the rear portion of the target 1, and the front side of the insertion portion 2 has a diameter larger than that of the insertion portion 2. The target portion 3 is formed. An annular permanent magnet 4 is attached to the back surface 30 of the target portion 3, and the insertion portion 2 is inserted into a bolt hole H formed in the bridge member B, and the back surface 30 of the target portion 3 is placed on the surface of the bridge member B. , The back surface 30 is attracted to the surface of the bridge member B by the magnetic force of the permanent magnet 4 so that the insertion portion 2 does not come out of the bolt hole H unless the finger is applied to the step portion 3a and pulled forward. Yes. On the other hand, an opening 31 that extends in a tapered shape toward the front is formed in the target portion 3, and a prism sheet 32 is attached to the bottom of the opening 31 to form a retroreflective surface. The virtual reflection surface of the prism sheet 32 is a retroreflection surface, and the bottom of the opening 31 is formed so that the position of the virtual reflection surface in the front-rear direction coincides with the back surface 30. On the surface of the prism sheet 32, as shown in FIG. 4, a circle 32a as an index and a crosshair 32b are drawn. The intersection of the center of the circle 32a and the cross line 32b is set so as to be located on the central axis of the insertion portion 2. In the present invention, three centripetal protrusions 21 are provided in the insertion portion 2 at equal intervals in the circumferential direction. In the insertion portion 2, the synchronization member 5 having a tapered portion 51 formed at the tip is sealed in a state of being biased forward by a spring 52. Each centripetal protrusion 21 is held so as to be movable forward and backward with respect to the insertion portion 2, and the tail end 21 a of the centripetal protrusion 21 is inclined and is in contact with the tapered portion 51 of the synchronization member 5. Accordingly, the urging force of the spring 52 acts on the tail end portion 21a of each centripetal protrusion piece 21 from the taper portion 51, and each centripetal protrusion piece 21 is always urged outward. When the tip of the centripetal protrusion 21 is pushed, a pushing force acts on the tapered portion 51 from the tail end portion 21 a, and the synchronization member 5 is returned backward against the biasing force of the spring 52. Since the synchronization member 5 is held so as to move back and forth in a state where the central axis of the synchronization member 5 coincides with the central axis of the insertion portion 2, each centripetal protrusion 21 moves forward and backward in synchronization, and each centripetal protrusion The center of the circumscribed circle passing through the tip of 21 is always located on the central axis of the insertion portion 2. Then, even if a relatively wide gap is formed between the outer peripheral surface of the insertion portion 2 and the inner peripheral surface of the bolt hole H as shown in FIG. The tip of each centripetal protrusion 21 abuts against the inner peripheral surface of the bolt hole H. Then, the center axis of the insertion portion 2 coincides with the center axis of the bolt hole H, and the intersection of the center of the circle 32a drawn on the prism sheet 32 and the cross line 32b is located on the center axis of the bolt hole H. Will do. In this state, if the coordinates of the target 1 are measured by collimating the cross line 32b with the distance measuring finder M, the coordinates of the target 1 become the center coordinates of the bolt hole H. Therefore, even if the outer diameter of the insertion portion 2 is formed so as to be relatively small so that it can be inserted into any bolt hole H in consideration of the machining accuracy of the bolt hole H, the central axis of the insertion portion 2 is the bolt hole H. The center coordinates of the bolt hole H can be accurately measured without deviating from the center axis of the bolt hole H.
[0009]
【The invention's effect】
As is clear from the above description, the present invention provides a centripetal protrusion on the insertion portion, and therefore, a gap is formed between the inner peripheral surface of the hole formed in the large structure and the outer peripheral surface of the insertion portion. Even so, the center coordinate measurement target can be mounted so as to coincide with the center axis of the hole, and when measuring the hole coordinates using a distance measuring instrument, a measurement error due to the mounting error of the center coordinate measurement target occurs. Absent.
[Brief description of the drawings]
FIG. 1 is a diagram showing the configuration of an embodiment of the present invention. FIG. 2 is a rear perspective view of a target. FIG. 3 is a cross-sectional view showing a target mounting state. ]
1 (for center coordinate measurement) target 2 insertion part 3 target part 5 synchronization member 21 centripetal protrusion 32 prism sheet

Claims (1)

In the center coordinate measuring target having a retroreflective surface at the front part, which has an insertion part to be inserted into a hole opened in a large structure at the rear part and an index located on the central axis of the insertion part, A synchronization member having a tapered portion at the tip is provided in the insertion portion so as to be urged forward by a spring , and at least three centripetal protrusions are provided at equal intervals in the circumferential direction of the insertion portion, The tail end of the projecting piece is inclined to contact the tapered portion of the synchronizing member, and the centripetal projecting piece is synchronously inserted so that the distance from the center axis to the tip of the inserting section becomes equal to each other. The center coordinate measuring target is characterized in that it protrudes from the outer peripheral surface of the indicator so as to freely advance and retract, and an annular permanent magnet is provided on the back surface of the indicator.

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