SU1249390A1 - Device for hydraulic machine for performing fatigue testing - Google Patents

Abstract

The invention relates to studies of the strength properties of materials. The purpose of the invention is to expand the functionality by automatically adjusting the load levels for a given program. The device contains serially connected force-measuring transducer 1, 2 and adder 3, the second input of which is connected to the third output of the programmer 4, the first and second outputs of which are connected respectively to the first inputs of the complexors 5 and 6, the second inputs are parallel-connected and connected to the output of the adder 3, and the outputs are respectively with the R and S inputs of the trigger 7, the output of the second is connected to the control element 8 of the two-position electrically controlled valve 9, the hydraulic lines of the are used to connect to the pump station 10 and b by the machine 11 pathogen. 12. When the load applied to the test object is reached, the value is greater than max, or less than min. the comparator 5 or 6 is activated and through the trigger 7 and the valve 9 the opening or closing of the drain line and the regulation of the magnitude of the applied load is controlled. 2 nl. CL 4; about 00 with FIG. 1

Description

The invention relates to the study of the strength properties of materials, ES in particular, to low-cycle fatigue tests, namely to control devices of a hydraulic fatigue testing machine.

The purpose of the invention is to expand the functional possibilities when using the device in machines with a two-way electro-controlled valve.

The goal is achieved due to a new feedback circuit structure including comparators, which are pulsed as threshold elements with an adder connected at their inputs, and a trigger at the output, which provides separate control of extreme load levels, as well as an average level according to a given law for a given load oscillation amplitude.

FIG. 1 is a block diagram of a control device for a hydraulic fatigue testing machine; in fig. 2 --- graphs of the dependence of the load signal P, with a programmatic change of the signals of the RMLX task (a), Rimim (b) IDRSr (c).

The control unit of the fatigue testing machine contains a force-measuring transducer 1 with an amplifier 2 connected to the ei o output, the output of which is connected to the first input of the adder 3, prog | 1a.matter

4 and two comparators 5 and 6 in the form of threshold elements, the second inputs of which are paralleled and connected to the output of the adder 3. The programmer 4 has three outputs for setting the maximum, minimum and average load levels respectively, the first two outputs of the programmer 4 connect with the first The inputs correspond to the first comparators 5 and 6, and the third output - with the second input of the adder 3. The device also contains a trigger 7, the inputs R and S of which are a key} 1Ы to the outputs of the comparators

5 and 6, and the output of the trigger 7 is connected to the control element 8 of a two-way electrically-controlled valve 9, the hydraulic lines of which are used for connection with the pump station 10 and the power actuator 11 12.

The control device of the hydraulic fatigue testing machine works as follows.

At the outputs of the programmer. The signals are set that correspond to the required load levels: at the first output, the signal Rmcx, corresponding to the maximum level at g) is narrow; at the second output, the Pmin signal corresponds to the minimum level of load; at the third output - the signal drsr. O, corresponding to the average level of load equal to Рср. (Rmax- {Rycho / g,

At the initial moment, the test object is not loaded, and the load signal at the output y; or the body 2 is equal to zero, respectively

at the output of the adder 3 and at the second inputs of the comparators 5 and 6 there is the same signal (since d Pcp. 0). With such a ratio of signals at the inputs of the comparators, i.e. when P (Rmnn. a comparator b is triggered, the signal from the output of which is fed to the input S of trigger 7 and sets it to state 1. At this, control element 8 opens a; 1-controlled valve 9, the working fluid from the pump station 10

About under pressure comes to the energizer hydraulic test mashina 12, due to which there is an increase in the load applied to the test object. The measurement of the load is carried out using a scoop transducer 1 with an amplifier 2, the signal from the output of which through the adder 3 is fed to the second inputs of the comparators 5 and 6. When the signal Pt increases to a value of sec. triggered comparator 5, the signal from the output of which

0 enters the input R of the trigger 7, transfers it to the “O” state, and the electrically controlled valve 9 closes the pump main, supplying pressurized fluid to the exciter 11, and opens the drain main, thereby reducing the load applied to the test object. When the signal P / decreases to P (P-lia triggers the comparator 6 and the loading cycle of the test object repeats.

The separate regulation of the maximum and minimum load levels is carried out by changing the Pmax and Pv.n reference signals to the first inputs of the comparators 5 and 6 from the first and second outputs of the programmer 4, respectively.

The transition to the test mode with another average load level or programming of the average level according to a given law is realized by means of changing the RF signal, the second input is received.

sum.mator 3 s third1 on the output of the programmer 4.

From) the test mode with the new values of the reference signals Rchaks, rmin and ARp is similar. Other programming options are possible with a combination of task signals.

The use of the invention allows for fatigue testing with automatic adjustment of load levels according to a predetermined program, which provides

0 increase the reliability of tests.

Claims (1)

Invention Formula A hydraulic control device for fatigue testing, which maintains the programmer of load levels, a force-measuring transducer, an amplifier under the output of its output, two co-meters, the first input of each connected to the output of the programmer, and an electrically-controlled valve, whose hydraulic lines serve to communicate with the pumping station and the machine’s energizer, characterized in that, in order to expand its functionality when using a device in machines with a two-position electro-controlled valve, it is equipped with an adder , the amplifier output is connected to one of the inputs, and the second are connected to the output in parallel the inputs of the comparators, and the trigger, whose inputs are connected to the outputs of the comparators, and the output to the valve control element, the programmer has three outputs for setting the maximum, minimum and average load levels respectively, the first two outputs of the programmer are connected to the first input of the corresponding comparator, and the third output - with a different input of the adder, and each of the comparators is made in the form of a threshold element.