JPS6337233A - Material tester - Google Patents

Abstract

PURPOSE:To prevent the application of overload with good response, by a method wherein the load applied to a crosshead is detected to judge an overload state and, when said load exceeds a tolerant value, the driving of crosshead is stopped or performed in a load reducing direction. CONSTITUTION:A crosshead 3 is mounted to screw rods 2, 2 and a grasping jig 6 is provided through a load cell 5 while a grasping jig 7 is provided to a table 1. A test piece 8 is grasped by the grasping jigs 6, 7 and load is applied to said test piece 8. At this time, the displacement of the crosshead 3 is detected on the basis of the number of rotations of the screw rod 2 by an encoder 11 to be inputted to a measuring control unit 15. The load of the test piece 8 is detected by the load cell 5 and inputted to the measuring control apparatus 15 and a comparator 16 through a load amplifier 13. The comparator 13 judges whether a load signal is within a tolerant set value and, at the time of an overload state, the stop signal of the servo motor 10 of the crosshead 3 or a drive signal for driving the crosshead 3 in a load reducing direction is outputted to a servo amplifier 3.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a material testing device, and particularly to a rod-type material testing device equipped with an overload prevention function.

[Prior Art] Generally, a rod-type material testing device has a closed-loop control system using a servo mechanism, and the displacement of the crosshead is controlled by feedback. Also,
It is also equipped with an overload prevention function to prevent overload from being applied to the test piece or load cell when moving the crosshead. For example, when a load signal is manually input to the measurement unit and the load signal indicates an overload condition, a limit switch installed on an analog recorder that records the load elongation curve is activated, and the servo amplifier of the load device is activated to stop the load. I try to follow orders. In addition, the A/D converter in Le 1 measuring section converts the load signal into a digital signal, and the CPU manually outputs a command to stop the load when it determines that the load has reached a set value indicating an overload condition. I try to do that.

[Problems to be solved by the invention] Conventional overload prevention +) When outputting a command to the servo amplifier to stop the crosshead by one means,
There is a problem in that as the number of circuits increases, H leakage occurs in response time.

[Means for Solving the Problems] In order to solve the above problems, the present invention provides the following material testing device.

That is, the material testing device according to the present invention is a material testing device that applies a load to a test piece by displacing the crosshead using a crosshead drive mechanism, and the load signal output from the load detector is manually input, and the load signal is determined to be within the allowable range. The present invention is characterized by the provision of a comparator device that determines whether or not the value is within a set value, and outputs a drive command to the crosshead drive mechanism to stop the drive or drive the crosshead drive mechanism in a direction to reduce the load if the tolerance value is exceeded.

1 action] Directly use load No. 13 output from the load detector to determine whether or not there is an overload condition, and send a drive command signal to the crosshead drive mechanism to stop the drive or drive in the direction of load reduction! j-
response is faster. Further, since the means for determining whether or not there is an overload state is configured as a comparator circuit, the number of circuits can be reduced.

[Embodiment] Fig. 1 is a diagram showing the configuration of an embodiment of the present invention, in which screw rods 2, 2 equipped with feed screws are erected on a table 1 of the testing machine main body, and screw rods 2, 2 are provided with feed screws. 1 is partially supported by a yoke 4. A crosshead 3 having a nut screwed onto the feed screw is attached to the screw rods 2, 2, and is moved downward by -F by rotation of the screw rods. An upper grip 6 is provided on the crosshead 3 via a load cell 5.

A lower gripping shell 7 is provided on the table 1, and a test piece 8 is held by these gripping tools 6,7.

A servo motor 10 is installed inside the table 1.

The screw rods 2, 2 are driven by the servo motor 10, the crosshead 3 moves up and down, and a load is applied to the test piece 8.

The displacement of the crosshead 3 is determined by detecting the rotational speed of the screw rod 2 by the encoder 11, and this displacement detection number 48 is output to the measurement control device 15 and the servo amplifier 12. The measurement control device 15 calculates the actual displacement of the crosshead 3 from this displacement detection signal and the pitch of the feed screw. The displacement detection signal output from the encoder 11 to the servo amplifier 12 is used as a feedback signal.
It is compared with a command signal output from the measurement control device 15 to the servo amplifier 12, and the crosshead 3 is subjected to follow-up control based on the output signal from the servo amplifier 12. The load applied to the test piece due to the displacement of the crosshead 3 is transferred to the load cell 5.
A load signal is output to the measurement control device 15 via the load amplifier 13.

Further, the load amount can be additionally controlled by comparing the load signal manually inputted to the measurement control device 15 with the command signal as a feedback signal.

The load signal from the load amplifier 13 is transmitted to the measurement control device 15.
At the same time, the comparator 16 is also manually powered. Comparator 16 determines whether this load signal is VRI or VH.
Determine whether or not it is within the allowable setting value set by 2,
When it is determined that there is an overload condition that deviates from the allowable set value, a command signal is output to the servo amplifier 12 to stop the servo motor.

The operation of this comparator 16 will be explained with reference to FIGS. 2(a) to 2(f). The voltages at each part of the comparator 16 on the VH2 side are determined as shown in FIG. Human power Vl is set value v
When V1 is larger than 2, V3 becomes 1, and when Vl is smaller than v2, it becomes +V ((b) in the same figure). Diode D1
Accordingly, v4 becomes as shown in the same figure (C). If the polarities of ■2 and DI shown in figure (a) are changed and the configuration is configured on the VRI side, the output characteristics shown in figure (b) and (c) will become the same as figure (d).
)(e). Therefore, in the configuration of the comparator 16 shown in FIG. 1, its human output characteristics are as shown in FIG. 1(f). In other words, load amplifier +3
When the human power from is within the set value, the servo amplifier 12
The feedback signal to becomes zero, and the crosshead 3 moves in response to the signal from the measurement control device 15, but when the input exceeds the set value, a stop +1- signal is output, and the movement of the crosshead 3 is stopped. . At this time, as shown in Fig. 2(f), the polarity of the feedback signal changes depending on the polarity of the overload, so the crosshead 3 moves in the direction in which the load decreases without stopping, depending on the polarity. You may also do so.

[Effects of the Invention] As is clear from the explanation in Section L, the material testing device according to the present invention is effective because when an overload is applied, a drive command is immediately output to the crosshead moving mechanism to stop the drive or to reduce the load. , 1F can now be prevented from being overloaded with a good response. In addition, the circuit configuration can be simplified and the allowable load value can be easily set.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the configuration of the embodiment, Fig. 2 (a) to (f)
FIG. 2 is a diagram illustrating the operation of a comparator. 3...Crosshead 5...Load cell lO
... Servo motor 12 ... Servo amplifier 13
...Load amplifier 15...Measurement control device 16
···comparator

Claims (1)

[Claims] (1) In a material testing device that applies a load to a test piece by displacing the crosshead using a crosshead drive mechanism, it is determined whether the load signal output from the load detector is within the allowable set value and the allowable value is determined. 1. A material testing device comprising a comparator device that outputs a drive command to the crosshead drive mechanism to stop the drive or drive the crosshead drive mechanism in a direction to reduce the load when the load exceeds the load.