JPS6150064A - Diagnosis of defect in square pilar - Google Patents

Abstract

PURPOSE:To handily detect a defect due to decay by white ants or the like within a square pilar, by determining the center of an internal defect from the propagation time of ultrasonic waves to connecting with a smooth curve points of contact obtained by drawing a perpendicular line to each external tangent from the center of the defect. CONSTITUTION:An ultrasonic wave transmission element abuts at peripheral positions M1 and M1' of an internally decayed square pilar to measure ultrasonic propagation time and determine the propagation time sequentially between the positions M2-M2',...M7-M7'. Likewise, the propagation time between the positions N1-N1'...N7-N7' is measured and the intersection between measurement lines indicating the longest propagation time gives the center of the defect. Then, a transducer is fixed near the mid-point of one side is fixed and then, moved farther along the adjacent side to find an external tangent to an internal defect from the rapid increase point of the propagation time. Then, points of contact obtained by drawing a perpendicular line to each external tangent from the center of the defect are connected by a curve to present the shape of the defect thereby detecting the defect.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a defect diagnosis method for diagnosing the shape and position of a defect inside a rectangular column using ultrasonic waves.

[Prior Art] The present applicant previously proposed a method for detecting defects in the center of the water column using relatively low-frequency ultrasonic waves (Japanese Patent Application No. 59-59042).
) was proposed. Therefore, this method will be briefly explained below.

FIG. 7 is a cross section of a wooden electrical silicon with a rotten part 1-1 in the center, and the outer circumference is divided into 16 equal parts 2. The positions P+, P2 .・・・・・・P +s. Then, the transmitting probe is brought into contact with the position P1 and the receiving probe is brought into contact with the position P2, and the propagation time is measured. Next, set the sending contact to +tl″
The propagation time is measured again with only the position R and the mouth position signal contact at position P3. As described above, only the receiving probe is placed at position Pi while the position of the transmitting probe is fixed.

Measure the propagation time while changing to Ps, P6 and P7. At this time, the relationship between the straight line distance &a L between both probes and the propagation time is shown in FIG.

At 83 in the plot in Figure 8, the receiving probe positions are P+, F2, F3, respectively from the smaller L.
Corresponding to F4, F5, Ps, F7 and 'Ps. As a result, it can be seen that when moving from F5 to F6 (the propagation time suddenly becomes longer). This is because there is a decayed part H in the middle of the ultrasonic propagation path connecting Pl and F6. As shown in the figure, the point in contact with the decayed part H is approximately the midpoint F of the line connecting Pl to the midpoint Q1 between F5 and F6.
Represented as 1.

Similarly to the above, the propagation time is measured while changing the position of the receiving probe to F4, Ps, . . . using F3 as the transmitting probe 28. If we do so, we can find the inflection point as in Figure 8, so we can find the approximate point F2 that is in contact with the decayed part H.
is required. Similarly, Ps, F7, F9
, pH, P+3. When measuring from P+5, P
+, F2..., Fg are obtained, and by connecting these with a straight line, the result shown in FIG. 9 can be obtained jq.

(Problems to be Solved by the Invention) Although the method described above is an effective diagnostic method for round materials, as is clear from a comparison of FIGS. 7 and 8,
However, since this method is only for diagnosing rot on circular wooden columns, it cannot be used for diagnosing internal defects on rectangular columns, and there has been a desire to develop a method for diagnosing decay in rectangular columns.

[Means for solving problems]

The method for diagnosing defects in a rectangular column according to the present invention involves measuring the ultrasonic propagation time between two pairs of pairs at several points in one cross section of the rectangular column, and determining that the propagation time at J5 between eight pairs of pairs is m long. The first step is to find the center of the defect from the intersection of the measurement lines, and fix one of the ultrasonic transmitter or the receiver near the midpoint of one side in the one cross section, and fix the ultrasonic transmitter or the receiver at a position close to the probe in the adjacent section. The other of the ultrasonic transmitter or the receiver is sequentially moved away from the center of the defect, and the second process is performed without finding the external tangent from the point where the propagation time rapidly increases to the internal defect. It is characterized in that defect detection is performed by a third process in which the defect shape is represented by connecting several contact points with a smooth curve by drawing a perpendicular line to the external tangent.

〔Example〕

Embodiments of the present invention will be described below with reference to FIGS. 1 to 6.

Figure 2 is a cross section showing an example of a rectangular column with internal decay.
For the following explanation, position symbols arranged at equal intervals on the outer periphery are written.

First, ultrasonic transmitters are brought into contact with positions M1 and M+' and the ultrasonic propagation time is measured. Next, the propagation time i11 between M2 and ~12'. lI, and sequentially M3 to M3'.

~14~~14', . . . M7~M7' are measured.

Mako, N1 ~ I'h',
N2 ~ N2', ... N
7 to N2' are similarly measured. The relationship between these positions and propagation time is shown in FIGS. 3(a) and 3(b). From now on, M4 to M4' and N4 to N
The maximum decay is on a', and the intersection of both lines is the center of decay Q
It can be seen that it is. That is, the ultrasonic waves cannot propagate through the decayed parts and take a long detour, but the ultrasonic waves take the longest detour in M4 to Ma' and N4 to N4'. In addition, in the case of a column with no decayed parts as shown in Figure 5, the propagation time becomes shorter when passing near the center of the tree ring, as shown in Figure 6, and Figures 3 (a) and (b) ) shows the opposite characteristics. Therefore, the presence of internal decay can be known from the characteristics shown in FIGS. 3(a) and 3(b).

Next, one of the probes is set to, for example, M
4 and the other at N7'. Next, while leaving Ml on the -5 side as it is, the other side was set to N61 and measured, and thereafter Ns', N4'
...N+', as we move away from the U-order M4, the propagation time of the planes becomes as shown in Fig. 4, and a sudden change in the propagation time appears in the middle. This is because the straight line connecting the probes crosses the decayed area, and this is the outer tangent of the internal decay. Therefore, the center of decay Q
By drawing a perpendicular line to this tangent line, the contact point J1 with the decayed part can be maintained. Next, move one probe to N, l.
If the measurement is carried out by fixing it at M7' and moving the other one away from M7' sequentially, point J2 of point 1a with the decayed part can be found in the same way as in the previous case. Thereafter, points J3 and Ja on the outer periphery of internal decay are determined by measuring each side in the same manner. And these four points J+, J2,
Due to the smooth curve connecting J3 and J4, the shape of the decay shape is fixed as shown in Figure 1.

〔Effect of the invention〕

As explained above, the method for diagnosing defects in rectangular pillars according to the present invention includes a first process of finding the center of an internal defect from the propagation time of ultrasonic waves, a second process of finding the circumscribed line to the internal defect, and a second process of finding the circumscribed line to the internal defect. By the third process of drawing a perpendicular line from the center to each external tangent line and connecting the stopping points with a smooth curve, it is possible to easily detect defects such as decay inside a rectangular column, and also to diagnose decay caused by termites, etc. It can also be used for

[Brief explanation of the drawing]

1 to 6 are diagrams for explaining the present invention. FIG. 1 is a diagram showing the shape of a defect in a rectangular column obtained by the present invention, and FIG. A diagram showing the shape, FIG. 3(a). (b) shows two of the rectangular pillars with internal defects shown in Fig. 2, respectively.
A diagram showing the relationship between the ultrasonic method 11G time and its 1111 fixed position between a pair of neighbors, FIG. 4 is a diagram showing the sharp increase point between propagation +1J found in the second process of this invention, and FIG. 5 is a diagram showing the cross-sectional shape of a rectangular column (10) with no internal defects, and FIG. Figures 7 to 9 are diagrams for explaining the diagnosis method for circular pillars previously proposed by the applicant, and Figure 7 shows the defect shape of the circular pillar targeted for diagnosis. A diagram representing
FIG. 8 is a diagram showing the relationship between the distance between the probes and the ultrasonic propagation time, and FIG. 9 is a diagram showing the defect shape of the circular pillar determined by the present diagnostic method. M1~M7 r M+'~My', N+~Ny, N
1 to N7'...Measurement point, H...Defect. Ward Ofu 0 N7'N6'N5'N4'N3'N2" N
l'Mt M2 M3 M4 M5 M6 M7
Figure 6〃S Figure 8

Claims (1)

[Claims] In a method of diagnosing internal defects in a rectangular column using ultrasound, the ultrasonic propagation time between two pairs of neighbors in one cross section of a rectangular column is measured at several locations, and the propagation time is the longest between each pair of neighbors. The first step is to find the center of the defect from the intersection of the measurement lines, and fix one of the ultrasonic transmitter or the receiver near the midpoint of one side in the one cross section, and measure the center of the defect from a position close to the probe on the adjacent side. A second step of sequentially moving the other of the ultrasonic transmitter or receiver away from the other to find the external tangent to the internal defect from the point where the propagation time increases; and also by drawing a perpendicular line from the center of the defect to each external tangent. The third point represents the defect shape by connecting several contact points with a smooth curve.
A method for diagnosing defects in rectangular columns, characterized in that defects are detected through the process of: