JPH0676957B2 - Material testing machine - Google Patents

Description

The present invention relates to a material testing machine, and more particularly to a material testing machine having an overload preventing function.

[Prior Art] In a conventional material testing machine, as shown in FIG. 5, a certain set value (105 in the figure indicates a load overload condition against a full-scale load in a load detector such as a load cell).
%) To prevent overload. That is, as shown in the flow chart of FIG. 6, every time the load Lt-elongation value is sampled, the load value Lt is compared with the load self-scale allowable value, for example, 105% value, and when the load value is large, the load device Is given to the load stop command.

[Problems to be Solved by the Invention] However, in the above-described conventional overload prevention method, in order to determine whether or not a preset overload set value has been reached and issue a stop command for the load device, the load increase When the speed is very high, there is a problem that the load cell is damaged before the overload prevention function operates due to a time lag until the load device stops.

Therefore, it is an object of the present invention to provide a material testing machine which can surely prevent overload even when the rate of increase in load is very fast and does not damage a load detector such as a load cell.

[Means for Solving Problems] In order to solve the above problems, the present invention employs the following configurations.

That is, the material testing machine according to the present invention, in a testing machine for detecting the load applied to the specimen by the load device by the load detecting means such as a load cell, the change amount of the load in the range of a preset load value or more. The load change amount detecting means for detecting, the reference change amount setting means for outputting a reference signal of a predetermined level, and the output signals of the load change amount detecting means and the reference change amount setting means are compared, and the output of the load change amount detecting means is compared. If the signal is larger than the output signal of the reference change amount setting means, a load stop command signal is output to the load device, and the output signal of the load change amount detecting means is smaller than the output signal of the reference change amount setting means, And a comparing means for outputting a load stop command signal to the load means when the detected load of the detecting means reaches the allowable upper limit value of the full-scale load of the load detecting means. And wherein the door.

[Operation] By the load change amount detecting means, the unit time of the load is reached until the load exceeds the load value set arbitrarily (for example, around 80% of the full scale load) and reaches the full scale allowable value of the load detecting means. The amount of change per hit is detected. By comparison means
When it is determined that this change amount is larger than the change amount set by the reference change amount setting means in consideration of the time lag of the load device, the comparison means outputs a stop command to the load device.
Even when the output signal of the load change amount detecting means is smaller than the output signal of the reference change amount setting means, when the detected load of the load detecting means reaches the allowable upper limit value of the full scale load of the load detecting means. Outputs a load stop command signal to the load means. Since the load device is stopped by this command, overload can be surely prevented even when performing a test with a high load increasing speed.

[Embodiment] FIG. 1 is a block diagram showing a configuration of the present invention. In a material testing machine 1, a load change amount detecting means 4 for detecting a load change amount from a load signal from a load cell 2 and a predetermined change amount. The reference change amount setting means 5 for outputting a level reference signal is compared with the output signals from these means, and when the comparing means determines that the load change amount exceeds the reference level, a stop command is output to the load device 8. And a comparison means 6 for

A concrete configuration of the embodiment is shown in the block diagram of FIG.
The weight signal from the load cell 2 is amplified by the weight amplifier 10 and input to the A / D converter 11. Here, the A / D converted load sampling value is input to the CPU 12, the signal processed by the CPU 12 is output to the recorder 13, and the recorder 13 records the load elongation curve during the test.

The CPU 12 is registered with the procedure for checking the load increase speed. That is, as shown in FIG. 3, the set level for checking the load increase rate is Lv (Lv is around 80% of the full scale load), and the sampling load Lt is Lv.
Check the increasing speed in the range from the point where the value exceeds the limit to the value of 105% of the full scale load (allowable limit). The processing procedure is performed according to the flowchart shown in FIG.
If the sampling load Lt exceeds the set level Lv and is within the range of 105% of the full scale load or less, whether the difference between the current sampling load Lt and the previous sampling load Lt-1 is larger than the set change amount ΔI. Is judged. The change amount ΔI is arbitrarily variably set by the reference change amount setting means 5, but is set to a value slightly larger than the elastic modulus value of the material of the test piece, and the time lag until the load device is stopped is taken into consideration. When the sampling load difference L _t −L _t−1 is larger than ΔI, a stop command is immediately output to the load device 8. When the load change rate is within the allowable value in the load increase speed check range (Lv or more), the stop command is output to the load device 8 when the value reaches 105% of the full-scale load as in the conventional case.

By outputting the stop command to the load device 8 in this manner, it is possible to prevent an overload and avoid a situation in which the load cell is damaged.

[Effects of the Invention] As is apparent from the above description, the material testing machine according to the present invention can reliably prevent overload even when a test with a very high load increasing rate is performed. It was

[Brief description of drawings]

FIG. 1 is a block diagram illustrating the configuration of the present invention, FIG. 2 is a block diagram showing the specific configuration of an embodiment, FIG. 3 is a diagram showing load curves for explaining the process of the present invention, and FIG. Is a flow chart showing a processing procedure, and FIGS. 5 and 6 are views for explaining a conventional processing method. 2 ... Load cell, 5 ... Standard change amount setting means 8 ... Load device, 12 ... CPU

Claims (1)

[Claims] 1. A test machine in which a load applied to a sample by a load device is detected by a load detection means such as a load cell, and a load change amount detection for detecting a load change amount in a range equal to or more than a preset load value. Means, the reference change amount setting means for outputting a reference signal of a predetermined level, and the output signals of the load change amount detecting means and the reference change amount setting means are compared, and the output signal of the load change amount detecting means sets the reference change amount. When it is larger than the output signal of the means, a load stop command signal is output to the load device, and the output signal of the load change amount detecting means is smaller than the output signal of the reference change amount setting means, and the detected load of the load detecting means is A material testing machine comprising: a comparing means for outputting a load stop command signal to the load means when the allowable upper limit of the full case load of the load detecting means is reached.