JPH0672042U - Spherical seat pressure plate device for compression tester with a part of spherical surface cut off - Google Patents

Abstract

(57) [Abstract] [Purpose] In the compression test of non-uniform materials with poor elastic deformation, such as concrete and stone, it is easy to cause local fracture before complete fracture, and spherical seat is perfect. When the spherical seat is operated smoothly, the spherical seat rapidly tilts in an avalanche direction in the direction of this local fracture and induces total surface failure to exhibit an abnormally low fracture strength. By eliminating such defects. [Structure] At least 30% of a notch for reducing the contact area is provided mainly in the center of at least one spherical surface portion (3, 4) of the male and female members (1, 2) forming a spherical surface.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a spherical seat pressure plate device for a compression tester in which a part of the spherical surface is cut off.

[0002]

[Prior art]

 The spherical seat device shown in FIG. 2 is known. The male and female members 41 and 42 forming the spherical seat 45 are in contact with each other over the entire surface of the spherical surface portions 43 and 44 having irregularities.

[0003]

[Problems to be solved by the device]

 In the compression test of non-uniform materials with poor elastic deformation such as concrete and stone, it is customary to cause local failure before total failure. Therefore, when the spherical seat operates completely smoothly like the conventional spherical seat device, the spherical seat rapidly tilts avalanche in the direction of this local fracture, inducing total surface fracture and exhibiting an abnormal low fracture strength. Let's do it.

In the case of a compression test, especially a concrete compression test, it may be required experimentally to use a pressure plate having a completely smooth spherical seat, but in a commercial test, it is usually required. Average strength of the specimen area is required. In view of this point, the present invention intends to provide a spherical seat device having a simple structure and eliminating such a defect.

[0005]

[Means for Solving the Problems]

 The spherical seat pressure plate device for a compression tester according to the present invention, in which a part of the spherical surface is removed, has at least 30% of notches for reducing the contact area mainly in the center of at least one of the male and female members forming the spherical surface. Set up.

[0006]

[Action]

 Adhesion due to slight non-parallelism between the upper and lower surfaces of the test piece is canceled by the use of a spherical seat pressure plate that operates sufficiently smoothly. The upper and lower pressure-resistant surfaces are in close contact with the upper and lower surfaces of the test piece, and the compression test starts loading smoothly. When a certain load is reached, the spherical stress increases, the oil film on the spherical surface disappears, and friction increases. In addition, since the average effective radius of the spherical surface is large, the spherical and spherical seat surfaces of both males and females are integrated, and compression continues until the initial state. For this reason, the average strength of the test piece is shown without being affected by local fracture, and abnormal low-strength fracture is prevented.

[0007]

【Example】

 Reference numeral 1 is a male member, 2 is a female member, and the convex spherical surface portion 3 of the male member 1 and the concave spherical surface portion 4 of the female member 2 form a spherical seat 5. A notch 6 formed by cutting off the convex spherical surface portion is provided mainly at the center of the convex spherical surface portion 3 in order to reduce the contact area.

The female member 2 is provided with a supporting spherical surface portion 7 concentric with the concave spherical surface portion 4 and having a radius larger than the radius on the outer peripheral surface thereof. A ring-shaped cover 8 has a supported spherical portion 9 having the same radius as the radius of the supporting spherical portion 7 on the inner side of the upper portion, and a plurality of bolt holes 10 are bored at an equal center angle in parallel with the axis. . Reference numeral 11 is an upper pressure plate, and 12 is a lower pressure plate. Both plates face each other vertically, and a test body 13 is sandwiched between them to press them.

Then, the cover 8 is fitted into the female member 2, and the supported spherical surface portion 9 thereof is brought into contact with the supporting spherical surface portion 7 of the female member 2. Then, the male member 1 is placed on the upper pressure plate 11, the convex spherical surface portion 3 thereof is put in the concave spherical surface portion 4 of the female member 2, and the bolt 14 is inserted into the bolt hole 10 of the cover 8 from above so that the upper pressure plate 11 Screw into. When these bolts 14 are properly tightened, the concave and convex spherical surface portions 3 and 4 of the male and female members 1 and 2 are slidably in close contact with each other. Reference numeral 2 is a rotation stopping screw.

Next, the mounting screw shaft 15 which stands upright from the female member 2 on its axis is inserted into the shaft hole 17 of the upper stage 16 of the testing machine, and the set screw 19 is inserted into the screw hole 18 opened to the side. Is screwed in and the tip thereof is engaged with the neck groove 20 of the screw shaft 15, and the female member 2 is set on the lower surface of the upper stay 16.

The test body 13 is placed between the upper and lower pressure plates 11 and 12 and pressurized. The upper and lower pressure plates contact the upper surface and the lower surface of the test body 13, respectively, but if both surfaces are not exactly parallel, the upper pressure plate 11 is tilted by the spherical seat 5 and the line of action of the force is applied to the test body. Align with the 13 axis.

When the load reaches a constant value, the spherical stress in the spherical seat 5 increases, and the oil film on the spherical surface disappears. Therefore, friction increases. Further, the average effective radius r ₁ of the spherical seat 5 is also larger than the average effective radius r _{2 in the} case of not having this notch because of the notch 6. Then, due to these actions, the male and female members 1 and 2 are integrated, and the compression is continued in the initial state. Therefore, it is hardly affected by the local fracture, and therefore, the abnormal low-strength fracture is prevented, and the average strength of the test body 13 can be measured.

[0013]

[Effect of device]

 According to the present invention, at least one of the male and female members forming the spherical seat is provided with a notch of at least 30% mainly in the center for the purpose of reducing the contact area, so that the spherical surface is reached when a certain load is reached. The stress can be increased to eliminate the oil film, the average effective radius of the spherical seat can be increased, and the influence of local fracture can be eliminated as much as possible, and the average strength can be measured.

[Brief description of drawings]

FIG. 1 is a cut side view showing a specific example of a spherical seat pressure plate device for a compression tester in which a part of a spherical surface according to the present invention is cut away.

FIG. 2 is a cut side view of a conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Male member 2 Female member 3 Convex spherical surface portion 4 Concave spherical surface portion 5 Spherical surface seat 6 Notch portion 7 Supporting spherical surface portion 8 Cover 9 Supported spherical surface portion 10 Bolt hole 11 Upper pressure plate 12 Lower pressure plate 13 Test body 14 Bolt 15 Screw shaft 16 Upper stay 17 Shaft hole 18 Screw hole 19 Set screw 20 Neck groove r ₁ Average effective radius r ₂ Average effective radius

Claims (1)

[Scope of utility model registration request] 1. A notch of at least 30% is provided mainly in the center of at least one spherical surface portion (3, 4) of at least one of the male and female members (1, 2) forming a spherical surface for the purpose of reducing the contact area. A spherical seat pressure plate device for a compression tester, in which a part of the spherical surface is cut off.