JP2000146565A - Shape measurement of plate type article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To measure a plate type article easily without hanging it with a crane by obtaining the maximum amount of deflection from the dimension of the plate type article on a supporting fixture and distributed load acting thereon, multiplying the obtained value by a predetermined amount of elastic deformation, and subtracting it from a measured current shape. SOLUTION: The current shape of a plate type article 9 supported by a plurality of supporting fixtures is measured by a shape measuring device 3. The measured result is sent to a computing part 5 by a controller 4 as the data of the shape (height) corresponding to a location. The supporting fixtures have a load detector respectively. A load measuring part 2A sends a detected load to the computing part 5 as data. The computing part 5 obtains distributed load acting on the plate type article 9 from the weight and the area thereof. A maximum amount of deflection is obtained from the dimension of the plate type article 9 and the obtained distributed load. The value is multiplied by the amount of elastic deformation of the predetermined and standardized plate type article 9, the measured current shape is subtracted, and the shape which is not made to act upon by external force except the effect of gravity or the like is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring a shape of a plate-like article deformed by its own weight, such as a large-sized metal plate, in a state where no external force is applied.

[0002]

2. Description of the Related Art In the field of shipbuilding and the like, large structures and hulls are manufactured using large-sized steel plates. In the case of a ship, a steel plate is formed into a curved surface by bending or the like, assembled into a structure such as a block, and then mounted to be built as a ship. Since these bent steel plates are assembled in a direction different from the direction at the time of bending, the direction in which the own weight works also differs. Since a large-sized steel sheet is deformed by its own weight, the shape of the steel sheet at the time of assembly generally differs from the shape at the time of bending.

[0003] In particular, a steel plate placed on a jig such as a support base is deformed as shown in FIG. 3 due to its own weight. in this case,
Since gravity acts almost perpendicularly to the plate surface, out-of-plane deformation such as warpage or bending is likely to occur in the steel plate. Generally, a large-sized steel sheet is deformed due to gravity during bending. For this reason, the curved surface that has been bent does not match the shape of the other parts when assembled, and welding work may be difficult. Therefore, in order to estimate the shape of the steel plate at the time of assembling, it is necessary to know the original shape that is not deformed by an external force such as gravity.

Therefore, conventionally, for the purpose of eliminating deformation due to gravity, as shown in FIG. 4, a steel plate is suspended by a crane to reduce the gravity component acting perpendicularly to the plate surface.
Observing the shape was done.

For materials other than steel plates, see JP-A-9-2
Japanese Patent No. 64702 proposes a method for measuring the amount of warpage of a sheet glass requiring flatness by a small number of workers to reduce the manufacturing cost of the sheet glass. In this method, first, the lower end portion of the plate glass is placed on a pair of support tables, and the upper end portion of the plate glass is held by a pair of holding tools to support the plate glass in an inclined state. Next, the sheet glass is held vertically by an air cylinder, and the warp detecting device is moved along the surface of the vertical sheet glass to detect the warpage of the sheet glass.

[0006]

However, in the method of observing the shape by suspending the steel plate with a crane as described above (FIG. 4),
Hanging a large steel plate with a crane is a rather large task. Further, in a normal rope hanging as shown in FIG. 4, a compressive force acts between the two hanging members as indicated by an arrow in the figure, and a bending stress is generated in the steel plate. As a result, there is a problem that the steel plate is bent and deformed, and the original shape cannot be observed.

Further, the technique described in Japanese Patent Application Laid-Open No. 9-264702 aims at measuring the shape of sheet glass, and when applied to a large-sized steel sheet, the framework of the apparatus itself becomes a large-scale facility. . This increases equipment costs,
A large installation space is required. Further, the steel plate to be measured is not always flat, and especially when used in the front and rear portions of the hull, it is often processed into a curved surface. Therefore, there is a problem that a device having a flat plate as a measuring object as in the related art cannot handle a plate-shaped article having a curved surface.

According to the present invention, the original shape of a plate-shaped article placed on a supporting jig and deformed by its own weight can be determined by simple measurement without using a crane or a large-scale facility. It is an object of the present invention to provide a method for measuring the shape of a plate-like article that is possible.

[0009]

SUMMARY OF THE INVENTION The present invention relates to a shape measuring method for a plate-like article for measuring a height-direction displacement of a rectangular plate-like article whose periphery is placed on a plurality of support jigs. Measure the current shape of the plate-shaped article on the support jig, obtain the distributed load acting on the plate-shaped article from the weight and area of this plate-shaped article, and obtain the dimensions of the plate-shaped article and the obtained distribution. Finding the maximum amount of deflection from the load, multiplying this value by the previously determined amount of elastic deformation of the plate-like article, and subtracting from the measured current shape, the shape of the plate-like article It is a measuring method.

The present invention removes the influence of gravity or the like from the current shape of a plate-like article placed on a plurality of support jigs.
A shape in a state where no external force acts, that is, an original shape is obtained.

[0011] Gravity acts as a distributed load proportional to the mass distribution of the plate-like article. This distributed load is a uniform distributed load when the plate thickness is constant, that is, an evenly distributed load, and the size per unit area is a value obtained by dividing the weight of the plate-like article by the area. Here, the weight of the plate-like article is equal to the sum of the loads acting on the support jig, and that value can be used.

The deformation when the plate-like article supported only at the periphery receives these distributed loads is expressed by an approximate expression based on superimposition of possible shapes determined by the supporting method. This approximation formula is a function using the position coordinates of the plane as a variable, and it is convenient to express the approximation by a two-dimensional Fourier series or the like.

An approximate expression representing the deformation of the plate on which the uniformly distributed load acts is standardized. For example, if the maximum value is standardized to 1, the deformation of the plate can be immediately obtained only by multiplying the maximum deflection amount. The maximum bending amount can be known from the result of the large bending analysis.

The amount of elastic deformation obtained in this way is the current shape, that is, the measured shape as a result of adding to the original shape. Therefore, the original shape is obtained by subtracting this elastic deformation amount from the measured shape.

[0015]

FIG. 1 shows the configuration of a system used in the present invention. The current shape of the plate-like article 9 supported by the plurality of support jigs 1 is measured by the shape measuring device 3. As the shape measuring device 3, a non-contact type shape measuring device such as a laser distance meter that can scan in the horizontal direction can be used. The shape measurement result is transmitted to the arithmetic unit 5 by the controller 4 as data of the shape (height) corresponding to the place.

Each of the plurality of support jigs 1 has a load detector. The load detector can be easily implemented by incorporating a load cell in the upper or lower part of the support jig 1 or attaching a strain gauge to the side surface of the support jig 1. The load measurement unit 2 transmits the detected load as data to the calculation unit 5. When the weight of the plate-like article 9 is separately measured, the load detector and the load measuring unit 2 may be omitted.

In the arithmetic section 5, based on these data,
The arithmetic processing described below is performed. Here, the shape of the plate-like article is represented by z = f (x, y), taking (x, y) coordinates in a horizontal plane and setting the height direction z.

The maximum bending amount is obtained by using a chart or the like representing the maximum bending amount of the plate. FIG. 2 shows the maximum amount of deflection when four sides are supported in a rectangular plate. The horizontal axis of the figure is the fourth power of the ratio of the short side b of the plate to the plate thickness t, the uniformly distributed load p,
And the reciprocal of Young's modulus E, and the vertical axis represents the ratio between the maximum flexure amount δmax and the plate thickness t.

The ratio of the long side a of the plate to the short side is a / b.
Is displayed as a parameter. In the figure, a /
Although two curves of b = 1.0 and 2.0 are shown, a chart having a curve between them can be used if necessary. Note that if a / b is 2.0 or more, the effect of a / b becomes small, and therefore it may be equal to a / b = 2.0.

Further, when two sides of a rectangular plate are supported, it can be considered that four sides are no longer effective for supporting the other two sides. Therefore, the maximum deflection amount δmax in this case corresponds to the case of a / b = ∞, and can be actually obtained using the curve of a / b = 2.0 as described above.

Assuming that the weight of the plate-like article is W, the distributed load p is given by p = W / S, where S is the area of the plate-like article when the plate thickness is constant. This distributed load p and the ratio of the length of the short side to the plate thickness b /
If the value obtained by multiplying t by the fourth power and dividing by the Young's modulus E is plotted on the horizontal axis, the ratio between the maximum flexure amount δmax and the plate thickness t can be obtained immediately from this figure.

Next, when the four sides of the plate are supported by jigs, the elastic deformation F (x, y) of the plate-like article due to the distributed load p
Is represented by the following approximate expression. F (x, y) = δmax · sin (πx / a) · sin (πy / b) (1) Note that the maximum value of sin (πx / a) · sin (πy / b) on the right side is 1
And is standardized as it is.

To further increase the degree of approximation,
It is expressed by the following equation using the Rie series. F (x, y) = Σ_mΣ_nc_mnsin (mπx / a) sin (nπy / b) × δmax / Σ_mΣ_nc_mn (2) c_mn= (Mn)^-1(m^Two/ a^Two+ N^Two/ b^Two)^-2 Where Σ_m, Σ_nIs only odd numbers of m and n (m = 1,3, ..., M, n = 1,
3, ..., N). The series censored order M, N is
Determine according to the required accuracy. In addition, 1 / Σ on the right side _mΣ_nc
_mnIs a coefficient for normalization. Thus, δ on the right side
Except for max, the maximum value is 1 and standardized.

The measured current shape f (x, y) has the elastic deformation F (x, y) added to the original shape.
Therefore, the original shape is obtained as f (x, y) -F (x, y) by subtracting the amount of elastic deformation from the measured shape.

[0025]

According to the present invention, the maximum amount of deflection is determined from the dimensions of the plate-like article on the support jig and the distributed load acting thereon, and this value is multiplied by a previously determined amount of elastic deformation to measure. The original shape is calculated by subtracting from the current shape. Accordingly, the original shape of the plate-like article can be obtained by simple measurement without using a crane or large-scale equipment.

[Brief description of the drawings]

FIG. 1 is a diagram showing a system configuration used for implementing the invention.

FIG. 2 is a diagram illustrating a maximum deflection amount (supported on four sides) of a rectangular plate.

FIG. 3 is a diagram showing a state of a plate-like article on a support jig in the related art.

FIG. 4 is a view showing a state of a plate-like article suspended by a crane according to a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Support jig 2 Load measuring part 3 Shape measuring device 4 Controller 5 Operation part 9 Plate-shaped article

Claims (1)

[Claims] 1. A plate-like article shape measuring method for measuring a height-direction displacement of a rectangular plate-like article whose periphery is placed on a plurality of support jigs. While measuring the current shape of the plate-shaped article, the distributed load acting on the plate-shaped article is determined from the weight and area of the plate-shaped article, and the maximum bending amount is determined from the dimension of the plate-shaped article and the obtained distributed load, A method for measuring the shape of a plate-shaped article, wherein the value is multiplied by a predetermined standardized elastic deformation amount of the plate-shaped article and subtracted from the measured current shape.