JPS588740B2 - Wedge type impact load test device with displacement control mechanism - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a wedge-type impact load testing device with a displacement control mechanism for measuring dynamic material properties of industrial materials.

Various industrial materials are often subjected to impact loads during use, and therefore, prior to designing equipment to be used in such environments, it is necessary to carefully consider dynamic materials that have a high rate of decay. Understanding the characteristics is extremely important in practical terms.

For example, in recent years, ASME Boiler and Press
ure Vessel Coades, Section
In Section I and Section X, it is mandatory to understand the dynamic fracture toughness value.

One method for determining this dynamic fracture toughness value is
There is a test method called the Jid test, in which the Jid value at the starting point of a stable crack is determined by drawing a diagram called an R-curp as shown in Figure 7A, which will be described later. In order to draw this R curve, it is necessary to apply different displacements A, B, C, and D to several test pieces, as shown in FIG. 1 of the attached drawings, for example.

Therefore, the device used for the JID test is required to be an impact loading device that can control the displacement given to the test piece.

However, conventional impact loading devices such as drop weight type, pendulum type, or rotating disk type have difficulty in controlling this displacement.
Therefore, it is difficult to apply it to the JID test.

On the other hand, as shock loading devices that can control displacement, there are currently examples of large-scale hydraulic devices being used. In addition to requiring a device, it also requires a sophisticated displacement mechanism, which has the drawback of making the device large-scale and expensive.

The present invention is to provide a low-cost impact load testing device that has a simple structure and is capable of displacement control, which eliminates the drawbacks of displacement control in a mechanical type and the disadvantages of large scale and high cost in a hydraulic type. Its purpose is to

In order to achieve this object, the present invention includes an impact force generating device including a falling weight and a falling weight receiver, an impact force transmitting device including a wedge that moves up and down integrally with the falling weight receiver, and an impact force transmitting device that engages with the wedge. a displacement device including a tension rond that applies the displacement caused by the wedge to the left and right, a displacement setting device including a position-adjustable setting nut and a mouth-dossel, and both ends supported by the displacement device and the displacement setting device. The present invention is characterized by comprising a test piece to which a strain or stress is applied according to the displacement, and a detection and measurement device that detects and measures the load on the test piece generated in response to the displacement.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the accompanying drawings showing one embodiment thereof.

As shown in FIGS. 2 to 4, the impact load test device according to the present invention mainly consists of five devices: an impact force generation device, an impact force transmission device, a displacement device, a displacement setting device, a test piece, a detection and measurement device, and a test piece. It consists of

The features and configuration of each of these devices will be explained below.

The first feature of the impact load test device according to the present invention is that the impact force generation source in the impact force generating device is a dropping weight type which is extremely simple in structure.

As shown in Fig. 2, this device consists of a falling weight 1 for generating an impact force by falling naturally, and a falling weight receiver 2 for catching the falling weight 1 and generating an impact force. , and a falling weight guide rod 3 having a falling weight receiver 2 fixed to the lower end for guiding the falling weight 1 and transmitting the generated impact force. It has a hole through which it can move and a connecting part for supporting it at a predetermined height with a stopper 4 at the upper end, and by arbitrarily changing the length, the falling distance of the falling weight 1 can be adjusted. A pipe-shaped falling weight stopper 6 is provided so as to penetrate and be fixed to the falling weight 1 so that it can be freely selected within the height range of the fixed bed 5.

Next, the second feature of the impact load test device according to the present invention is:
In the impact force transmission device and displacement device, the impact force generated by the falling weight 1 is not directly transmitted to the test piece 7, but by providing a wedge 8 in the middle, the structure is expected to amplify the generated impact force. It's what I did.

As shown in FIGS. 2 and 3, the structure of this device is mainly a wedge 8 connected to a falling weight guide rod 3 and movable in the vertical direction, and contact with this wedge 8. A tension rod 9 slides in a direction perpendicular to the direction of movement of the wedge 8 as it moves up and down, and transmits the impact force amplified by the wedge 8 to the test specimen 1; 9 and a first block 10 for incorporating the block 9.

This combination of the wedge 8 and the tension rod 9 is as shown in FIG. The wedge 8 and the tension rod 9 are in contact with each other, and the wedge 8 and the tension rod 9 are connected to the first base so that the axis X-X of the wedge 8 and the axis Y-Y of the tension rod 9 are orthogonal to each other. It is incorporated in 10.

Further, the angle θ of the wedge 8 can be appropriately selected depending on the desired degree of amplification of the impact force, but in the device of the present invention, it is preferably in the range of about 7.5 to 10'.

In addition, in order to avoid an increase in frictional resistance due to fatigue at the contact point 14 between the contact pin 13 provided on one side of the groove-shaped through hole of the tension rod 9 and the wedge 8, the wedge 8 is
and the contact pin 13 are made of high hardness material.

Furthermore, a high-hardness roller-shaped wedge receiver 15 is provided on the sliding surface between the wedge 8 and the first block 10, and a sliding sliding surface between the tension rod 9 and the first block 10 is provided. Also, a ball bearing 16 exclusively for linear motion is provided to reduce friction loss.

Next, the third feature of the impact load test device according to the present invention is:
In the displacement setting device, the displacement to be applied to the test piece 7 is set by a combination of the displacement setting nut 17 and the wedge 8.

As shown in FIG. 2, this device mainly consists of a displacement setting nut 17, a load measuring load cell 19 to which a strain gauge 18 is attached, and a displacement setting nut 17.
7 and a second block 20 for incorporating and supporting the load cell 19, the wedge 8, and the tension iron 9.
It is composed of etc.

This displacement setting nut 17 is screwed into the load cell 19 from behind the load cell 19 passing through the second block 20, that is, from the end opposite to the test piece mounting jig 21 with respect to the second block 20. Therefore, after the test piece 7 is installed between the tension rod 9 and the load cell 19, by rotating the displacement setting nut 17, they slide together in their axial direction, and their As a result, the position of the contact point 14 of the wedge 8 on the contact pin 13 provided on the tension rod 9 before being loaded can be moved and changed from side to side, and based on this, the wedge 8 also moves up and down.

Therefore, when the displacement setting nut 17 is rotated to bring the contact point 14 of the tension rod into contact with the wedge 8, and the wedge 8 is completely pulled out in the direction of fall due to the falling weight 1, the contact point 14 is brought into contact with the wedge 8. From point 14 to the highest point 2 of wedge 8
The horizontal distance up to 2 is the displacement given to the specimen 7,
It becomes possible to arbitrarily set the displacement within the range of the height h of the wedge 8.

Next, as shown in FIG. 4, the detection and measurement device in the impact load test apparatus according to the present invention includes a clip gauge 23 for detecting the displacement of the test piece 7, and a clip gauge 23 for measuring the load that caused the displacement. strain gauge 18 affixed to the load cell 19, first and second amplification devices 24 and 25 for amplifying the outputs generated by the clip gauge 23 and the strain gauge 18, respectively, and for storing the respective output signals. It consists of a two-channel digital memorizer 26, a synchroscope 27 for visualizing and recording the aforementioned output signals, and an X-Y recorder 28 for graphing both of these output signals. , it is necessary to use one with a sufficiently high response frequency in order to cope with shocking phenomena.

Note that some of these components may be replaced with others depending on conditions, or some may be omitted.

The device of the present invention is constructed as described above, and its operation is as follows.
An impact load test device used in the Jid test, which is an example, will be described next.

First, the test piece 7 has a tension rod 9 and a load cell 1.
9, but this test piece 7 is attached between the fifth
As shown in the figure, predetermined positions at both ends of the test piece 7 are fixed by pins 29 to predetermined positions of each test piece device jig 21 fixed to the tension rod 9 and the load cell 19, respectively.

Next, by rotating the displacement setting nut 17 and moving the tension rod 9 left and right, the wedge 8 is moved up and down to set the displacement so that a predetermined displacement position is obtained.

Next, a clip gauge 23 is attached to the displacement detection part of the test piece 7, and the falling weight 1 is fixed by being connected to the upper end of the falling weight stopper 6 and the stopper 4, which is set at a predetermined height.

In this way, after the test preparation is completed, the stopper 4 is pulled to both ends to release the connection, and the falling weight 1 is allowed to fall naturally and falls into the falling weight receiver 2, that is, by colliding with the falling weight stopper 6, Creates a shock load.

The impact force generated by this falling weight receiver 2 is
The force is transmitted to the wedge 8 through the tension rod 9, and the wedge 8 is impulsively pulled in the direction of fall, causing the highest point 22 of the wedge 8 to be pulled out of the contact pin 13 set on the tension rod 9.

Due to this movement of the wedge 8, the tension pad 9 slides in the Y-Y axis direction, and the test piece 7 is subjected to an impact force amplified by the wedge 8.

At this time, as shown in Fig. 3, the impact force S generated by the falling weight 1 is greatly amplified by the wedge effect;
This amplified tensile impact force F of the tension rod 9 is:
From the relationship with the angle θ of the wedge 8, F=S/tanθ.

Also, the speed in the direction in which the wedge 8 is pulled out is VK,
Assuming that there is no loss, the impact loading speed VT on the test piece 7 is VT=VKtanθ.

This impact loading speed can be arbitrarily set by changing the height of the falling weight 1.

The strain and stress applied to the test piece 7 in this way are detected by the clip gauge 23 and the strain gauge 18 attached to the load cell 19.
The output signals of are amplified by amplifiers 25 and 24 and stored in a digital memorizer 26, and the stored signals are later read out and visualized by a synchroscope 27, and are also recorded by an X-Y recorder 28. Record to end this test cycle.

Generally, in such an impact load test, there is a problem of inertia force appearing in the load-displacement curve at the time of initial loading, but in the impact load test device according to the present invention, the optimal falling weight 1 is determined depending on the test material and test temperature. By selecting the weight and fall height, the effect can be reduced to a negligible level.

Note that FIG. 6 shows an example of a load-displacement curve obtained by conducting a Jid test using the apparatus of the present invention.

Since the device of the present invention is constructed and operates as described above,
Despite the loading method using the falling weight 1, which is structurally very simple, it is possible to obtain a significantly increased impact force due to the transmission of the impact force via the wedge 8, and therefore,
Even small-sized testing machines can be used to test industrial materials with relatively large test specimen cross-sectional areas, and as mentioned above, the combination of wedge 8 and displacement setting nut 17 makes it very easy to test. It is possible to control the amount of displacement applied to the test piece 7, and thereby, the amount of displacement applied to the test piece 7 can be controlled.
For example, it has become possible to perform a dynamic fracture toughness Jid test.

Note that FIG. 7A is an example of an R curve showing the test results.

As mentioned above, this figure is a diagram for determining the fracture toughness value Jid of a material, and is usually called an R curve.
The blunted straight line P represents the fatigue crack tip Bll of 2) whose front view is shown in Figure 2.

(Fig. 7F) and the R line P1 (Fig. 7F) indicating the growth of a stable crack formed at the tip, and the Jid value defined as the J value at the point of stable crack initiation. is a diagram for determining the intersection point P2 of the two straight lines.

The method for obtaining this diagram is shown below.

First, as shown in the load-(load point) displacement curve in Figure 7C, several test pieces are loaded at high speed to different displacements, and the area K under the load-displacement curve is calculated for each of them. .

Next, as shown in FIG. 7D, the test piece was heated and colored, then fractured, and the fatigue pre-crack length a was measured from the fracture surface.

, test piece width W, test piece thickness H, and crack growth amount Δa, respectively.

The J value is then calculated from the relationship, and is plotted as shown in FIG. 7E in relation to the measured crack growth amount Δa with the vertical axis as the vertical axis and the horizontal axis as the J value.

And the R line P1 and the blunted straight line P.

is determined by referring to the experimental points, and the intersection point P is determined as shown in Figure 7F.
Jid is determined as 2.

Based on the above procedure, in order to obtain the dynamic fracture toughness value Jid, it is necessary to apply a predetermined displacement at high speed in the process shown in Figure 1C, and the wedge-type test device with this displacement control mechanism is effective. It is.

Further, although the above embodiments have been described with respect to a specially shaped test piece, the present invention is not limited to this, and the present invention can also be applied to a normal tensile test piece as shown in FIG.

Generally, in metal material testing, relationships between various properties of the material and temperature are often determined, but the impact load testing device according to the present invention uses a simple thermostatic chamber 30 as shown in FIG. Furthermore, by providing an electric furnace (not shown), low-temperature or hot tests can be conducted in the range of -196°C to 400°C, making the apparatus of the present invention extremely useful. The test device is compact overall and has a simple structure, so it is very economical as an impact loading device with a displacement control mechanism, and it does not have the difficulty of displacement control, large size, and high cost of conventional devices. In addition, it has the effect of being widely applicable to various tests and industrial materials, and furthermore, the dynamic material properties obtained using the device of the present invention are academically extremely important. The interesting results and the effects that provide guidance cannot be overlooked.

[Brief explanation of the drawing]

Fig. 1 is a load-displacement diagram in the Jd test, Fig. 2 is a longitudinal cross-sectional view of an embodiment of the impact load test device according to the present invention, and Fig. 3 is an enlarged cross-section near the contact point between the wedge and the tension rond. Fig. 4 is a system conceptual diagram of the load-displacement measuring device of the above-mentioned embodiment, Fig. 5 is a sectional view taken along line 1 - 2 of Fig. 2, and Fig. 6 is a system diagram of the load-displacement measuring device according to the above embodiment. Figure 7A is a load-displacement diagram for an example of the JID test conducted using the impact load test device according to the present invention.
Diagram showing the R curve obtained in an example of the id test, 7th
Figures B1 and B2 are side and front views of the test piece, Figures 7C and D
, E, and F are simplified diagrams for explaining the procedure of FIG. Fig. 8 is a longitudinal cross-sectional view of the main part when the impact load test apparatus according to the present invention is applied to a tensile test, and Fig. 9 is a longitudinal cross-sectional view of the main part when the shock load test apparatus according to the present invention is equipped with a constant temperature bath. It is. 1... Falling weight, 2... Falling weight receiving, 3...
... Falling weight guide rod, 4 ... Stopper, 5
...Fixed bed, 6... Falling weight prevention, 7
...Test piece, 8...Wedge, 9...
...Tension rod, 10...First block, 11...Groove-shaped through hole, 12...
・Side surface, 13...Contact pin, 14...
Contact point, 15... Roller wedge receiver, 16...
...Linear motion ball bearing, 17... Displacement setting nut, 18... Strain gauge, 19...
...Load cell, 20...Second block,
21...Test piece device jig, 22...Top top of wedge 8, 23...Clip gauge, 2
4...First amplifier device, 25...Second amplifier device, 26...2 channel digital memorizer, 27...Synchroscope, 28...
...X-Y recorder, 29...Pin, 3
0... Constant temperature bath.

Claims (1)

[Scope of Claims] 1. An impact force generating device including a falling weight and a falling weight receiver; an impact force transmitting device including a wedge that moves up and down integrally with the falling weight receiver; a displacement device including a tension rond that applies the displacement generated by a wedge; a displacement setting device including a position-adjustable setting nut and a cord cell; An impact load testing device comprising: a test piece to which a strain or stress is applied; and a detection and measurement device that detects and measures the load on the test piece generated in response to the displacement. 2. The engagement between the wedge and the tension rod is such that the wedge is brought into contact with one side of a groove-shaped through hole formed in the tension rod via a contact pin. Shock load test equipment.