JPH0521163B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for measuring the amount of elongation suitable for strain control of steel wires, particularly for strain control of PC steel stranded wires.

(Background Art) Conventionally, in order to measure the strain of a steel wire, it is common to use a strain gauge bonded to the steel wire.

However, when measuring the elongation of stranded wires, a strain gauge is glued to one of each strand, but if the strands are thin, gluing becomes difficult, and the elongation of the entire stranded wire varies from the elongation of a few strands. Conversion may be required, making it difficult to obtain accurate results. Furthermore, in the case of irregularly shaped wires, it was not possible to bond the gauge when the pitch of the unevenness was small.

Another common method for measuring the elongation of a wire is to glue a strain gauge to a rod-shaped measuring piece and clamp both ends of the measuring piece to the steel wire, thereby measuring the amount of elongation of the wire. However, this method is suitable when only a relatively small tensile load is applied, but when a large load is applied, such as with a PC steel wire, it is difficult to fix the steel wire and the measurement piece. This method could not be used to measure the elongation of PC steel wires because errors were likely to occur and the amount of elongation could not be measured accurately. For this reason, the elongation of PC steel wire has conventionally been measured using a load cell, but this method has problems such as troublesome installation and high cost.

On the other hand, in the PC method, it goes without saying that it is desirable to measure the elongation of each stranded wire in order to manage the tension of the PC steel wire.
Because it is difficult to measure the load on each individual item, the reality is that the load on several dozen items is measured at once using a large-capacity load cell.

Therefore, in the conventional method, even if tension is applied unevenly to each PC steel wire and the amount of elongation of each PC steel wire is uneven, it is not possible to directly measure the amount of elongation of each PC steel wire. However, the tension of the PC steel wire cannot be managed properly, leading to problems such as some of the PC steel wires breaking.

(Object of the Invention) This invention was devised in order to solve the above-mentioned problems in the method of measuring the amount of elongation of a PC steel wire, and it is an object of the present invention to reliably and easily attach a strain gauge to each PC steel wire. It can be installed and accurately measure the elongation of PC steel wire even under heavy loads, and it is small and can be used in narrow spaces.
The purpose of this invention is to provide a method for measuring the amount of elongation of a PC steel wire that allows for proper tension management of the PC steel wire.

(Structure and Effects of the Invention) Hereinafter, the present invention will be described in detail with reference to the drawings.

Figure 1 shows one of the sleeves used in this invention.
This is a sectional view of an embodiment, in which a flat part 3 is formed near the center of the outer surface of a sleeve body 1 having a hole 2 into which a steel stranded wire or the like is inserted, and a bonding part for a strain gauge 4 is formed. 5 is an insertion hole for the lead wire 6 of the gauge 4.

After the strain gauge 4 is bonded to the sleeve 6 as shown in FIG. 1, the sleeve 6 is crimped and fixed at any position of the stranded wire 7 by extrusion, as shown in FIG. 2. At this time, the plane part 3 is not deformed by the extrusion process, and the hole 5 is designed so that the cutting depth of the plane part 3 into the main body 1 and the insertion hole are determined so that the lead wire 6 will not be crushed and the resistance value will not change. Adjust the size of 5.

In the embodiment of FIG. 3, the sleeve 1' has approximately the same dimensions as the compression grip used in the anchor, and the strain gauge 4' may be bonded after extrusion.

The stress distribution of the sleeve crimped to the wire as described above is as shown in Figure 4, and is low at both ends and high at the center, so it is necessary to keep the gluge bonding position almost constant at the center of the sleeve. Therefore, the sleeve structure shown in the first figure is preferable from the point of view of specifying the bonding position.

FIG. 5 shows the measurement sleeve 1 attached to a plurality of stranded PC steel wires under simultaneous tension, with reference numeral 9 a compression grip and 10 a support plate.

(Effects of the Invention) This invention has the above-mentioned configuration, and the measurement sleeve is integrated with the PC steel wire, so that even if a large tension is applied to the PC steel wire and plastic elongation occurs in the steel wire, no slipping occurs. The amount of elongation can be measured accurately.

The load on the PC steel wire can be immediately converted from the elongation obtained with the above gauge using a load-elongation diagram.

The measuring sleeve can be made small and easy to install, allowing it to be used in narrow spaces that were previously impossible, such as when tensing multiple PC steel wires at the same time.
It is possible to measure the elongation of 11 PC steel wires at a time.

Long-term measurement is possible by applying anti-rust treatment, resin coating, etc., and it can be widely applied to wire ropes, parallel steel wire groups, composite wires, etc.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of one embodiment of the measuring sleeve used in the present invention, FIGS. 2 and 3 are conceptual diagrams showing its crimp-fixed state, FIG. 4 is a stress distribution diagram inside the measuring sleeve, and FIG. The figure is a conceptual diagram of one application example. 1: Measuring sleeve, 3: Flat part, 4: Strain gauge, 5: Lead wire insertion hole, 7: PC steel stranded wire, 8: Press part, 9: Compression grip, 10: Support plate.

Claims (1)

[Claims] 1. A single measuring sleeve is crimped and fixed to a PC steel wire by extrusion processing, and a strain gauge glued near the center of the outer periphery of the measuring sleeve is used to
PC characterized by measuring the amount of elongation of PC steel wire
Method for measuring elongation of steel wire. 2. The amount of elongation of the wire according to claim 1, wherein the measuring sleeve has a flat part near the center of the outer periphery that remains unprocessed during crimping, and a strain gauge is bonded to the flat part. Measuring method.