JPS625632Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a strain detector that detects strain in a test piece based on changes in actuator stroke in a material testing machine that performs fatigue tests on materials. This invention relates to a strain detector suitable for attaching and detaching test pieces.

Conventionally, in strain detectors equipped with an inductive transducer that detects the axial strain of a test piece via a lever by changing the stroke of an actuator that applies a load to the test piece, it is difficult to measure displacement compared to the actuator stroke. It has been made extremely small to improve detection accuracy, so if the actuator stroke moves significantly when attaching or detaching a test piece, etc.
If the lever is beyond its movable range, there is a risk of damage. For this reason, conventionally, the operation of attaching and detaching the strain detector and the operation of attaching and detaching the test piece are performed in parallel, but this operation becomes complicated and inefficient.

The present invention was devised to solve these conventional difficulties, and its purpose is to avoid overstroke even when the actuator is operated with a stroke that exceeds the displacement of the strain detector, and to enable the testing machine to detect strain. To provide a strain detector in which a test piece can be attached and detached while the instrument is attached.

The present invention applies the axial strain of the test piece to the end of the lever that swings in conjunction with the strain of the test piece, one end of which swings in conjunction with the strain of the test piece, from a fixed position during the test. An auxiliary lever is provided that can swing only in the direction of compression of the piece and return to the normal position using a spring force, and the lever and the test piece are interlocked via this auxiliary lever, thereby preventing overstroke. It is designed to avoid this.

The present invention will be described below based on an embodiment of a horizontal material testing machine.

In FIG. 1, reference numeral 1 is a material testing machine main body, and this material testing machine main body 1 has a test piece 3 attached to a fixed part 2 through a pressure platen 4 in a tensile direction as shown by arrow A in FIG. An actuator 5 that applies a repeated load with the pressure platen 4 side and the compression direction facing the fixed part 2 side.
is provided. And this material testing machine main body 1
A strain detector 6 is attached to detect the strain in the axial direction of the test piece 3.

As shown in FIGS. 1 and 2, the strain detector 6 includes an inductive transducer 8 having a movable core 7, a saddle 9, and a stopper 1 having a damper 10a.
0, arm 11, guide rod 12, catch 13, first
It is composed of a lever 14, a second lever 15, and the like.

Inductive transducer 8 with movable core 7
is held by a saddle 9 on which a stopper 10 is protruded, and this saddle 9 is attached to a guide rod 12 fixed to the material testing machine main body 1 via a catch 13 via a screw 9a. It is fixed so that it can be moved in position. As shown in FIG. 1, an arm 11 is provided at the lower end of the saddle 9 to protrude in parallel with the induction transducer 8 and the stopper 10. A first lever 14 is optionally attached. The upper end of this first lever 14 is connected to the movable iron core 7 via an adjusting screw 17 as shown in FIG.
The spring 18 causes the first
It is biased counterclockwise in the figure.

A substantially L-shaped second lever 15 is swingably attached to the lower end of the first lever 14 via a shaft 19, as shown in FIGS. 1 and 3.
The lever 15 is biased clockwise in FIG. 3 by a spring 20 whose one end is latched to the arm 11, and is also biased clockwise in FIG. 3 by a stopper 21 attached to the lower end of the first lever 14. It is installed so that it can swing only in the compression direction of the test piece 3, and is prevented from swinging clockwise beyond the state shown. A sloped portion 15 is provided on the back side of the lower end of this second lever 15.
a is provided, and the front surface of the lower end of the second lever 15 comes into contact with a transmission ring 22 provided on the pressure platen 4, as shown in FIGS. The signal is transmitted to the 14th side.

In FIG. 1, the dashed line X--X indicates the axis of the material testing machine.

Next, the effect will be explained.

When detecting strain, first move the saddle 9 to the guide rod 1 depending on the length of the test piece 3 held on the fixed part 2.
2, and the second lever 15 is brought into contact with the transmission ring 22 of the pressure platen 4 against the spring 18 so that the first lever 14 becomes almost vertical. Then, the movable core 7 is displaced by the adjustment screw 17 to determine the zero point of the transducer 8.

The actuator 5 moves the arrow A shown in FIG.
When a load is applied to the test piece 3 in the direction and strain occurs in the test piece 3, the first lever 14 with the shaft 16 as a fulcrum is displaced together with the second lever 15 by the transmission ring 22, and due to the displacement of the movable iron core 7. Inductive transducer 8 outputs.

When attaching or detaching the test piece 3 to the fixed part 2, the stroke of the actuator 5 moves significantly toward the material testing machine main body 1 side. Then, the first lever 14 swings clockwise in FIG. 1 through the transmission ring 22 against the spring 18, and finally
The lever 15 and the transmission ring 22 come out of contact.
As a result, the first lever 14 is reversed (swung counterclockwise) to the stopper 10 by the biasing force of the spring 18, and this contact reaction force is alleviated by the damper 10a. At this time, the transmission ring 22 is connected to the second lever 1
5 reaches the rear inclined portion 15a side.

When the test piece 3 is attached to the fixed part 2 and the actuator 5 is moved to the test piece 3 side, the transmission ring 22
A pressing force is applied to the back surface of the second lever 15, and the second lever 15 uses the shaft 19 as a fulcrum and the spring 2
0 in the direction of arrow B shown in FIG. 3, resulting in the state shown by the chain line in FIG. When the transmission ring 22 passes the second lever 15 position, the second lever 1
5 returns to the solid line position shown in FIG. 3 by the biasing force of the spring 20.

As explained above, according to this embodiment, even if the test device actuator is operated with a stroke exceeding the movable displacement of the strain detector, this stroke is mechanically avoided to prevent damage and the strain detector Since the strain detector is protected, it is possible to attach and detach the test piece or move the actuator stroke significantly while the strain detector is attached to the test machine, and settings for test pieces of different lengths can be easily moved. Since it can be adjusted, test efficiency can be improved.

In the above embodiment, the case where the strain detector 6 is attached to the horizontal testing machine has been described, but the strain detector 6 may be attached to the vertical testing machine, or the second lever 15 may be provided with a sensor. , the passage of the stroke of the actuator 5 may be detected by this sensor.

The present invention has been described above based on a preferred embodiment. According to the present invention, overstroke is avoided even when the actuator is operated with a stroke exceeding the displacement of the strain detector, and the strain detector is mounted on the testing machine. The test piece can be attached and detached without changing the position.

[Brief explanation of the drawing]

Figure 1 is a front view showing one embodiment of the present invention;
The figure is a plan view of the strain detector shown in FIG. 1, and FIG. 3 is an enlarged view of the second lever portion. 1... Material testing machine main body, 2... Fixed part, 3...
Test piece, 4... pressure plate, 5... actuator,
6... Strain detector, 7... Movable iron core, 8... Inductive transducer, 14... First lever, 15...
...Second lever, 16, 19...Shaft, 18, 20...
... Spring, 21 ... Stopper, 22 ... Transmission ring.

Claims (1)

[Scope of utility model registration request] An induction type transformer that detects the axial strain of the test piece by changing the stroke of the actuator that applies a load to the test piece via a lever whose one end swings in conjunction with the strain of the test piece, with the longitudinal center as an axis. In a strain detector equipped with a deducer, an end of the lever on the side that is connected to the test piece is configured to be able to swing only in the direction of compression of the test piece from a home position and return to the home position by a spring force. A strain detector characterized in that an auxiliary lever is provided, and the lever and the test piece are interlocked via the auxiliary lever.