JPH05249015A - Method for bending proof test of ceramic - Google Patents

Abstract

PURPOSE:To provide a method for bending proof test for enabling proof for defects of a whole ceramic test piece. CONSTITUTION:A plurality of ceramic test pieces 4 are placed on a surface of an elastic belt 2, and a load roller 1 provided to apply a predetermined load to the surface of the elastic belt 2 is rotated while it is relatively moved along a lengthwise direction of the elastic belt 2. Thus a plurality of ceramic test pieces 4 are continuously interposed between the load roller 1 and the elastic belt 2 supported by a support roller 3, and a bending load is applied to the ceramic test piece 4 by the load roller 1 to have a bending proof test performed. Since the bending load can be applied to the entire test piece 4, proof for defects of the entire test piece 4 is possible.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bending strength assurance test method for ceramics.

[0002]

2. Description of the Related Art Structural ceramic parts that receive a load are usually commercialized after undergoing a load (stress) guarantee test. This is because the ceramic material has a large strength variation mainly due to pores and defects, and the reliability of the strength is low. The above-mentioned guarantee test is performed by applying a load slightly higher than the actual stress in a state as close as possible to the actual load as a part, and immediately after removing the load,
As a result, the destroyed low-strength parts are removed (see "Fine Ceramics Evaluation Technology Collection, Comprehensive Technical Data", Realize Co., Ltd., issued 1987.25).

Specifically, a load is applied to the test piece by a plane bending test method, a radial bending test method, or the like. In the plane bending test method, as shown in FIGS. 6 and 7, a ceramics test piece 92 is placed on a pair of rod-shaped supports 91, 91, and one rod-shaped pusher 9 is placed at the center of the rod-shaped supports 91, 91.
There is a three-point bending test method in which a load is applied with No. 3, and a four-point bending test method in which a load is applied with two bar-shaped pushing tools 93 in the center of the above-mentioned bar-shaped supporting tools 91, 91. In addition, as shown in FIGS. 8 and 9, the radial bending test method includes a ring-shaped support 9
4, a ceramics test piece 95 is placed on top of it, and a rod-shaped pusher 96 is used to apply a load to the pin-on-ring test method, or a ring-shaped pusher 97 is used instead of the rod-shaped pusher 96.
There is a ring-on-ring test method in which a load is applied at.

[0004]

However, in the bending load system of two-point support or ring-shaped support as described above, stress load cannot be applied to the outside of the support point. For this reason, it is not possible to guarantee defects in the outer peripheral portion of the ceramics test piece. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a bending strength assurance test method for ceramics, by which a load is applied to the entire ceramics test piece and it is possible to guarantee defects in the entire ceramics test piece. And

[0005]

In order to solve the above-mentioned problems, a method for testing the bending strength guarantee of ceramics of the present invention is to place a ceramic test piece on the surface of a plate-like elastic body placed on a rigid support, By rotating a load roller arranged on the surface of the plate-like elastic body so that a predetermined load can be applied thereto while relatively moving in one direction on the surface of the plate-like elastic body, the ceramics can be rotated between them. The test piece is sandwiched, and a bending load is applied to the ceramic test piece by the loading roller.

[0006]

In the method for guaranteeing bending strength of CERAX of the present invention, the load roller arranged so that a predetermined load can be applied on the surface of the plate-like elastic body is rotated on the surface of the plate-like elastic body. Is relatively moved in one direction, and the ceramics test piece placed on the surface of the plate-like elastic body is sandwiched between the plate-like elastic body and the load roller. As a result, the ceramic test piece is brought into close contact with the load roller by the elastic force of the plate-shaped elastic body supported by the rigid support body, and the bending load is applied to the same curvature as the outer circumference of the load roller according to the load of the load roller. In addition, a bending strength assurance test is performed. At this time, a bending load is applied to the ceramic test piece over the entire load roller, so that it is possible to guarantee defects in the entire ceramic test piece.

[0007]

EXAMPLES The present invention will be specifically described below with reference to examples. (Embodiment 1) In this embodiment, a bending strength assurance test is carried out on a large number of ceramics piezoelectric plate ceramics test pieces 4 used in a laminated piezoelectric actuator. The thickness of the ceramic test piece 4 was t = 0.
It has a disk shape of 5 mm and an outer diameter: b = 20 mm.

As shown in the perspective view of FIG. 1, the test apparatus used for this test comprises a load roller 1, an elastic belt 2 as a plate-like elastic body, and a supporting roller 3 as a rigid supporting body. There is. The load roller 1 has a shaft center 1 at its center.
A cylindrical core 12 made of aluminum in which 1 is inserted
And an outer surface portion 13 made of a high hardness steel material that is integrally formed on the surface of the core portion 12 by heat treatment (see FIG. 2).
), Its radius: R ₁ is 250 mm, width is 200 mm
belongs to. The shaft core 11 is rotatably supported by a support base (not shown).

The radius R ₁ of the load roller 1 can be set as follows. When the bending moment is M, the elastic modulus of the ceramic test piece 4 is E ₄ , and the second moment of area is I, the following equation (1) is obtained from the relational expression of material mechanics.
Is given. 1 / (R ₁ + t) = M / E ₄ · I (1) Further, from other relational expressions of material mechanics, required guarantee test stress: σ
Then, the following equations (2), (3), and (4) are given.

[0010] ^{I = b · t 3/12} ... (2) Z = b · t 2/6 ... (3) M = σ · Z ... (4) _{where, σ = 100MPa, E 4 =} 100GPa, t =
When set to 0.5 mm, the above formulas (1), (2),
(3), (4) than the radius: calculating the _{R 1, R 1 = E 4} · I / M-t = E 4 · (b · t 3/12) / (σ · b · t 2/6) _{-t = t · E 4 / 2σ} -t = (0.5mm) (100GPa) / (2 × 100MPa) - a (0.5m m) ≒ 250.

The elastic belt 2 is a rubber belt main body (spring hardness 70 Hs, width 200 mm) 21 with a cord.
And a coating layer 22 of a single rubber formed on the surface of the rubber belt body 21 (see FIG. 2), and a width of 200
mm endless belt. The rubber hardness of the coating layer 22 is 80 Hs in spring hardness, and the rubber hardness of the coating layer 22 is 70 to 90 H in spring hardness.
It can be set to about s. The elastic belt 2 needs to have an elastic modulus for deforming the ceramics test piece 4 and bringing it into close contact with the load roller 2. Further, the total thickness T of the elastic belt 2 is set to 12 mm so that the elastic belt 2 itself can elastically deform and contribute to the deformation of the ceramics test piece 4.

The support roller 3 is made of aluminum, and a drive shaft 31 connected to a motor (not shown) is inserted in the center of the support roller 3. The radius R ₃ of the supporting roller ₃ is 50.
It is 0 mm. The supporting roller 3 radius: R ₃ is, the larger the ceramic test piece 4 through the elastic belt 2 in order to uniformly adhere to the load rollers may, be set to more than 2 times the radius of at least the load roller Is preferred.

The axial distance L between the load roller 1 and the support roller 3 is set to 760 mm. The distance L between the axes can be set as follows. That is, when the amount of deflection of the elastic belt 2 is α, the above-mentioned inter-axis distance: L is given by the following equation. L = R ₁ + R ₃ + T + t−α Here, by attaching a strain gauge to the surface of the load roller 1 and changing the inter-axis distance: L variously, the amount of deflection of the elastic belt 2: α change. From the strain measurement result at this time, the deflection amount required for the specified strain amount: ε ₀ : α
Can be asked. Specifically, R ₁ = 250m
m, R ₃ = 500 mm, T = 12 mm, t = 0.5 mm
As a result of measurement at the time of, as shown in FIG. 3, the relationship between the deflection amount α and the generated strain ratio, if the axial distance: L is set so that the deflection amount α becomes 1.7 mm or more, the prescribed strain is set. As shown in FIG. 3, the amount of deflection can be obtained, and even if the amount of deflection: α is increased, the increase in strain is small. Therefore, in order to reliably apply bending stress to the test piece 4, in the present embodiment, the axial distance: L
Was set to 760 mm, and the amount of deflection: α was set to 2.5 mm.

A bending strength guarantee test was carried out using the test apparatus having the above-mentioned structure. On the surface of the elastic belt 2, six ceramic test pieces 4 were evenly arranged in the width direction of the elastic belt 2 to form one row, and the intervals between the rows were 20 mm, and a large number of ceramic test pieces 4 were arranged. The support roller 3 was rotated by the operation of a motor (not shown), and the elastic belt 2 was moved at a feed rate of 180 mm / min. At this time, the load roller 1 also rotated synchronously. The ceramic test pieces 4 placed side by side on the surface of the elastic belt 2 are continuously sandwiched between the elastic belt 2 and the load roller 1, so that the elastic force of the elastic belt 2 causes the ceramic test pieces 4 to be closely attached to the load roller 1. According to the load applied by the load roller 1, a bending load is applied up to the same curvature as the outer circumference of the load roller 1, and a bending strength guarantee test can be performed.

According to the bending strength assurance test method of CERAX of this embodiment, a bending load can be applied to the entire ceramic test piece 4, and it is possible to guarantee defects such as the outer peripheral portion of the test piece 4. Further, the bending strength guarantee test can be carried out simultaneously and continuously with respect to a plurality of ceramics test pieces 4, and the test capability is significantly improved as compared with the conventional test method. The specific testable number is (6
Number of sheets) × (1800 mm / min) / (20 mm) = (5
40 sheets / min). (Embodiment 2) In the above-mentioned Embodiment 1, an example in which the elastic belt 2 is moved in the longitudinal direction with respect to the load roller 1 whose position is fixed has been described. The load roller 1 is moved on the surface of the elastic belt 2 while applying a predetermined load to the roller 1.

As shown in FIG. 4, the apparatus of this embodiment comprises a load roller 1, an elastic belt 2 as a plate-like elastic body, and a rigid plate 5 as a rigid support made of aluminum. .. The load roller 1 is similar to that of the first embodiment and is connected to a load applying device (not shown), and the load applying device is movable in the longitudinal direction of the elastic belt 2 at a predetermined speed. The elastic belt 2 is made of the same material as in Example 1 and is an end belt.

On the surface of the elastic belt 2, six ceramic test pieces 4 are evenly arranged in the width direction of the elastic belt 2 to form one row on the surface of the elastic belt 2, and the distance between each row is 20 mm. A large number of columns of 4 were arranged. 180 mm feed speed while applying a predetermined load: P ₁ to the load roller 1.
/ Min, the surface of the elastic belt 2 was moved in its longitudinal direction. As a result, the same bending strength guarantee test as in Example 1 could be carried out.

The load applied to the load roller 1 is P
₁ is set according to the required amount of deflection of the elastic belt 2: α, and a calculation example of the amount of deflection is set to 1.7 to 2.5.
The case of setting to mm will be described below. First, when the contact width between the load roller 1 and the elastic belt 2 is 2a, as shown in FIG. 5, a ² = R ₁ ^2- (R ₁ -α) ² and R ₁ = 250 mm, α = 1 From 7 to 2.5 mm, a = 29 to 35. Here, the vertical load per unit length of the load roller 1 is P, the Poisson ratio of the load roller 1 is ν ₁ , the elastic modulus of the load roller 1 is E ₁ , and the Poisson ratio of the elastic belt 2 is:
In the Hertz's formula, where ν ₂ and the elastic modulus of the elastic belt 2 are E ₂ , a = 2 [(P / π) {(1-ν ₁ ² ) / E ₁ + (1-ν
₂ ² ) / E ₂ } / (1 / R ₁ + 1 / R ₂ )] ^1/2 R ₁ = 250 mm, R ₂ = ∞, ν ₁ = 0.3, ν ₂ =
Substituting 0.45, E ₁ = 210 GPa, E ₂ = 6 MPa, and a = 29 to 35, P≈19.9 to 29.0 N / mm, and multiplying this by the width 200 mm of the load roller 1 yields P ₁ ≈ 3.98 to 5.79 kN (406 to 591 kg
f).

[0019]

As described in detail above, the bending strength guarantee test method for ceramics of the present invention can apply a bending load to the entire ceramic test piece, so that it is possible to guarantee defects in the entire test piece. Further, according to the test method of the present example, it is possible to simultaneously and continuously perform a bending strength guarantee test on a plurality of ceramics test pieces, and the test capability is significantly improved as compared with the conventional test method. ..

[Brief description of drawings]

FIG. 1 is a perspective view schematically showing a test apparatus according to a first embodiment.

FIG. 2 is an enlarged sectional view of the device.

FIG. 3 is a diagram showing a relationship between a flexure amount of a rubber belt and a generated strain ratio in the above apparatus.

FIG. 4 is a perspective view schematically showing a test apparatus according to a second embodiment.

[FIG. 5] In the above device, the amount of deflection of the elastic belt: α
It is a figure explaining the relationship between and the contact width 2a.

FIG. 6 is a front view illustrating a plane bending test method according to a conventional test method.

FIG. 7 is a plan view illustrating a plane bending test method according to a conventional test method.

FIG. 8 is a front view illustrating a radial bending test method according to a conventional test method.

FIG. 9 is a plan view illustrating a radial bending test method according to a conventional test method.

[Explanation of symbols]

1 is a load roller, 2 is an elastic belt as a plate-like elastic body,
3 is a support roller as a rigid support, 4 is a ceramic test piece, and 5 is a rigid plate as a rigid support.

Claims (1)

[Claims] 1. A load arranged so that a ceramic test piece is placed on the surface of a plate-like elastic body placed on a rigid support, and a predetermined load can be applied to the surface of the plate-like elastic body. By rotating the roller while relatively moving in one direction on the surface of the plate-like elastic body, the ceramic test piece is sandwiched between the two, and a bending load is applied to the ceramic test piece by the load roller. Bending strength assurance test method for characteristic ceramics.