JPH01244365A - Centrifugal soil testing apparatus - Google Patents

Abstract

PURPOSE:To fix an arm and a bucket as a unitary body during the test and to prevent a minute movement, by providing a position holding device, and operating a position fixing device when the bucket receiving centrifugal force becomes horizontal with the tip of the arm. CONSTITUTION:When a test is started and centrifugal force reaches a specified amount after the start of the rotation of a driving shaft 1, a bucket 3 becomes a horizontal state as the tip of an arm and continues the rotation. When the bucket 3 reaches this state, oil pressure is applied to a pushing device 20. Then, a ram is extended, and a pushing plate 20a is strongly pushed to the side surface of the bucket. Since the reaction is supported with a supporting table 19, the bucket 3 is apparently fixed to the arm as a unitary body through an upper position holding device (comprising the pushing plate 20a, the pushing device 20 and the supporting table 19).

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a centrifugal force type soil testing device that can perform soil testing while applying centrifugal force to soil.

[Conventional technology]

When designing and constructing the foundations of structures, dams, roads, etc. that are made of soil, it is very important to know the properties of soil, and therefore chemical tests, physical tests, strength tests, etc. Various tests are conducted depending on the purpose. The centrifugal soil testing device that is the subject of this article is designed to apply centrifugal force to the soil, thereby increasing the apparent weight of the stop and reproducing the actual condition in the laboratory, allowing various tests to be carried out. It is what was done.

For example, the foundation (±) of the above structure is under pressure commensurate with the weight of the structure and the weight of the soil, so if you want to investigate the properties of the foundation in that state, you can arbitrarily adjust the centrifugal force applied to the test. It can be used to reproduce the pressure conditions in real soil and can be carried out in the laboratory.

A conventional centrifugal force type soil testing device is shown in FIGS. 3 and 4.

In the figure, reference numeral 1 denotes a drive shaft, which is rotatably fitted and supported by a main bearing 5 supported by a foundation 9. An arm 2 is fixedly attached to the main bearing 5 at its center, and a bucket 3 (3') is attached to a hinge 16 at the tip of the arm 2.
It is rotatably attached via the The bucket 3 is a sample box 4 that stores the soil to be tested or a structural model.
(Four pieces are placed on the drive shaft. A power transmission device 6 is installed at the bottom of the drive shaft 1, and the rotation of the motor 7 is transmitted to the drive shaft 1 via the transmission shaft 8 to achieve the required rotation. It is designed to give

A rotary hydraulic joint 11 is attached to the upper end of the drive shaft, and serves to transmit the hydraulic pressure sent from the external hydraulic piping 15 (or IF) to the piping inside the rotating shaft 1. By supplying hydraulic pressure to the hydraulic jack 13, a desired test load is applied to the test specimen 14.

Additionally, an electrical slip ring 12 is installed at the lower end of the drive shaft to accommodate the test load or test object.

The input/output signals obtained by electrically converting the stress, displacement, etc. received can be taken out to the outside.

The entire device is shielded from the outside by a protective wall 1o to ensure safety against unexpected accidents.

In addition, one set of buckets 3 and 3' can be set at the tip of the image of arm ■, so two sets of specimens can be tested at the same time, but if you want to test only one set, you can place the counter in the other set of sample boxes. Attach weights to maintain balance during rotation.

Before the drive shaft 1 rotates (before the test), the bucket 3 hangs down as shown by the dotted line in the figure (the same applies to the sample box). The motor is driven and the drive shaft 1 is connected via the power transmission device.
When the bucket 3 begins to rotate, the bucket 3 receives a centrifugal force and begins to rotate once again while maintaining a horizontal state, and a predetermined centrifugal force acts on the test specimen 14 in the sample box 4, so the test specimen 14 in that state Various tests are carried out on 14.

[Problem to be solved by the invention]

The bucket 3 hangs from the arm 2 via the hinge 18 until the drive shaft 1 rotates, but when the drive shaft 1 rotates, it eventually swings up horizontally in the axial direction of the arm 2 due to the centrifugal force and is fully extended. In this state, it continues to rotate together with arm 2. However, since the bucket 3 is rotatably connected to the arm 2 via a hinge, there is always some looseness at the hinge, which may cause fluctuations in rotational speed or other factors such as the test load on the sample box 4 or test specimen 14. There is a problem in that minute positional movement (backlash) occurs due to application, which adversely affects test accuracy.

The present invention aims to solve the above problems.

(Means for solving the problem) In order to ensure that the above-mentioned play in the hinge joint does not occur during the test, a position holding device is installed so that the bucket, which has been subjected to centrifugal force, is positioned horizontally at the tip of the arm. Activate the fixing device to fix the arm and bucket so that they do not move.

When the test is completed, the fixation of the bucket is released and the drive shaft stops rotating, leaving the bucket hanging from the arm again.

[For production]

With the above configuration, the arm and bucket can be integrally fixed during the test, and minute movement can be prevented.

〔Example〕

An embodiment of the present invention is shown in FIGS. 1 and 2.

The position holding device includes a support stand 19, a pressing device 20 (in this case, a hydraulic actuator such as a hydraulic jack), and a pressure contact plate 2.
It consists of 0a, etc. Other elements are the same as the conventional example.

The support stand 19 is fixed by the tip of the arm 2 and the mounting port 22, and is configured such that the tip faces the side surface of the bucket 3 at a predetermined distance, and between the tip and the side surface of the bucket 3 there is a pressure plate attached to the tip of the ram. A pressing device 20 with 20 is inserted.

The pressing device 20 is fixedly attached to the tip of the support base 19. Further, 20b and 20C indicate hydraulic piping, and the pressing device 20
The hydraulic actuator is designed to supply or discharge hydraulic pressure to the hydraulic actuator.

21 is an excitation device, which is attached to the bucket 3 and is attached to the sample box 4 (
A test load (in this case, earthquake motion) is applied to the test specimen (or test specimen).

Note that before the test, the pressure contact plate 20a and the side surface of the bucket 3 were separated as shown by the dotted line in the figure. After paddy was harvested and the test started,
When the drive shaft 1 begins to rotate and the centrifugal force reaches a predetermined level, the bucket 3 becomes horizontal like the tip of the arm and continues to rotate. When bucket 3 is in this state.

Hydraulic pressure is supplied to the pressing device 20. Then, the ram expands, and the pressure contact plate 20a is strongly pressed against the side surface of the bucket.

Since the reaction force is supported by the support stand 19, the bucket 3 is apparently fixed integrally with the arm 2 via the position holding device (pressing plate 20a, pressing device 20, support stand 19).

In this way, even if a test load is applied to the sample box 4 (or the test specimen) by the vibrating device 21 or other unnecessary external forces are applied, the hinge joint will not undergo slight positional movement, allowing for highly accurate testing. It can be performed.

When the test is completed, the supply of hydraulic pressure to the pressing device 2o is stopped and the system is switched to discharge.The pressing plate 20a and the side surface of the bucket 3 are separated from each other, and their positions are released, so when the rotation of the drive shaft 1 stops, the bucket 3 is removed. is restored to the state where it hangs from arm 2.

Note that it is effective to use two position holding devices as a pair to press and hold the bucket from both sides as shown in the figure.

〔Effect of the invention〕

During the test, by operating the position holding device between the arm and the bucket, the joint between the two can be seemingly fixed as one body, so even if a test load or other unnecessary external force is applied, slight movement will not occur. , it is possible to perform highly accurate tests.

[Brief explanation of the drawing]

FIG. 1 is a partially enlarged plan view showing one embodiment of the present invention, and FIG.
The figure is a view taken along the ■-■ line in Figure 1, Figure 3 is an overall elevational view showing the conventional device, and Figure 4 is a view taken along the line ■-■ of Figure 1.

Claims (1)

[Claims] A drive shaft that is supported by a set of bearings and rotates in an upright state, a pair of left and right arms that are fitted and fixed to the drive shaft, and a pair of buckets that are rotatably connected to the tips of the arms.
a sample box placed on the bucket and storing soil or other test material as a test object therein; a support stand fixed to the arm; a pressing device attached to the support stand; A centrifugal force type soil testing device comprising a position holding device that presses the device against the side of the bucket while the testing machine is rotating to fix or release relative movement of the arm and the bucket.