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Universal Testing Machine Description

2017-05-22

Universal Testing Machine Description



Universal testing machine, with tensile, bending, compression, shear, ring stiffness and other testing functions of the material testing machine, mainly for metal, non-metallic materials, mechanical properties test, universal testing machine is used for the various industries, scientific research units, universities, engineering quality Supervision stations and other departments of the ideal testing equipment.

 

The definition of universal testing machine

Universal testing machine is also called tensile testing machine, or universal tester, double screw series, control, measurement, operation integration structure, integration of contemporary advanced technology in one, with high precision, wide speed range, compact structure, easy operation, Stable performance and so on. So this tensile testing machine is suitable for drawing, compression, bending and creep testing of materials and articles such as plastic, waterproof material, textiles, paper products and rubber. And universal testing machine is directly used for flat compression (compression recovery), ring stiffness ( Anti-external load), creep ratio, ring tensile strength and other tests.

Universal material testing machine is a combination of modern electronic technology and mechanical transmission technology, universal tester is to give full play to the mechanical and electrical characteristics of their own large-scale precision test equipment, can be a variety of materials for stretching, compression, bending, stripping, cutting, etc. A number of performance tests, and a wide range of measurement, high precision, fast response and so on. Reliable, high efficiency, the test data can be real-time display records, print.

 

Universal testing machine main components:

Universal material testing machine is composed of measuring system, drive system, control system and computer (computer system type tensile testing machine) and other structures.

 

Universal testing machine classification:

If the universal testing machine on the market in accordance with the use of classification, can be assigned to determine the mechanical properties of the testing machine. According to the use of the test machine can be divided into two types of testing machine:

 

1. Universal test machine for measuring mechanical properties

In addition to the universal testing machine, the A-static load testing machine includes a tensile tester, a pressure tester, a torsion testing machine, a composite stress tester, a creep testing machine, and a durable test machine. Strength testing machine, relaxation test machine and the hardness of the Brinell, Rockwell and Vickers hardness. B-dynamic load testing machine: including impact testing machine, fatigue testing machine and the hardness of the impact of Brinell and Shore hardness.

tensile testing machine supporting equipment: high and low temperature test chamber, high temperature furnace, low temperature box, all kinds of equipment.

Tensile test high temperature furnace: supporting the use of hydraulic universal testing machine and electronic universal testing machine for its samples to provide high temperature environment. Electric furnace shell made of stainless steel, furnace bile using the upper, middle and lower three heating, three temperature controller were controlled three sets of heating wire, the furnace temperature uniformity. Using PID fuzzy control mode, the test temperature overshoot is small, high control accuracy, is the institutions of higher learning, scientific research institutions, factories and mines research unit of high-performance materials test equipment. Can be used in accordance with the use of environmental requirements and any combination of the host, can complete a variety of metal, non-metallic high temperature tensile test, and can achieve a variety of special industries (such as plastic, rubber) and other requirements. Do at room temperature test only need to remove the high temperature furnace, can fully meet the GB / T4338-2006, HB5195-1996 in the round bar samples, rectangular specimens, pipe, etc., in the special ambient temperature strength test.

 

Universal test machine for process test

Universal testing machine process test machine: including the cup sudden test machine, spring testing machine, bending test machine and wire torsion testing machine. measuring system

Force measurement

Measured by force sensors, amplifiers and data processing systems, the most commonly used force sensors are strain gauge sensors.

The so-called strain gauge sensor, that is, by the strain gauge, elastic components and some accessories (compensation components, protective cover, wiring socket, the composition of the load), can be a kind of mechanical power into the device. Strain gauge pull, pressure sensors at home and abroad a wide range, mainly cylindrical force sensor, spoke force sensor, S double hole type sensor, cross beam sensor and other types.

It is known from the material mechanics that under a small deformation condition, the strain of a certain elastic element is proportional to the force of the elastic element and is proportional to the deformation of the elasticity. In the S-type sensor, for example, when the sensor is subjected to the action of the pulling force P, since the strain gage is attached to the surface of the elastic member, since the strain of the elastic member is proportional to the magnitude of the external force P, the strain gauge is connected to the measuring circuit By measuring its output voltage, which measured the size of the force.

 

 

For the sensor, the general use of differential full-bridge measurement, is about to paste the strain gauge bridge,

R1, R2, R3, R4, the actual resistance of the four equal (or 8) strain gauge, that is, R1 = R2 = R3 = R4, when the sensor by external force (tension or pressure), the sensor elastic components produce strain And the resistance value changes, the change values were R1, R2, R3, R4, the original balance of the bridge, is now unbalanced, the bridge has a voltage output, set E

E = [R1R2 / (R1 + R2) 2] R1 / R1-R2 / R2 + R3 / R3 - R4 + R4) U

Where U is the voltage of the external power supply bridge

Further simplification Yes

E = [R2 / 4R2] (R1 / R- R2 / R +R3 / R -R4 / R) U

Will Ri / Ri = Ki on behalf of the above formula

Then ΔE = [UK / 4] (1 - 2 + 3 - 4)

In simple terms, the force P causes the deformation of the strain gauge in the sensor, resulting in the imbalance of the bridge, which causes the sensor output voltage to change. We can know the size of the force by measuring the change of the output voltage.

In general, the sensor output signal is very weak, usually only a few mV, if we directly on the signal measurement, is very difficult, and can not meet the high-precision measurement requirements. So the amplifier must be amplified by this amplifier signal, amplified signal voltage up to 10V, this time the signal for the analog signal, the analog signal through the multi-channel switch and A / D conversion chip into a digital signal, and then data processing, At this point, the measurement of force come to an end.

 

 

Deformation universal testing machine measurement

Measured by a deformation measuring device, which is used to measure the deformation of the specimen during the test.

The device has two chucks, through a series of transmission mechanism and installed in the top of the measuring device [photoelectric encoder] together, when the distance between the two chucks change, driving the photoelectric encoder shaft rotation, photoelectric The encoder will have a pulse signal output. And then by the processor to deal with this signal, you can get the deformation of the sample.

 

Operating procedures:

the main switch connected to power.

according to the sample, the use of measuring range, hanging on the pendulum or take the thallium and adjust the buffer valve handle, alignment mark.

according to the sample shape and size of the corresponding chuck into the upper and lower jaws.

in the digger on the drum, the volume of good recording paper (checkered paper), this is only when necessary.

start the pump motor, unscrew the valve to make the test paper up 10 mm, and then close the valve, if the test bench has been in the raised position when you do not have to open the oil pump, only the oil valve can be closed.

will be one end of the specimen caught in the jaw.

start the pump to adjust the pointer alignment plate zero.

start under the jaw motor, the lower jaw up and down to the appropriate height, the other end of the specimen caught in the next jaw, should pay attention to the sample vertical.

put down the painted pen on the putter into the drawing preparation state (need to be painted).

press the test required loading speed, slowly unscrew the oil valve for loading test.

After the specimen is broken, close the oil valve and stop the pump motor.

The record needs the value and will be depicted.

Open the return valve, unloading the passive needle back to zero.

Remove the specimen after fracture.

compression and bending test can refer to the above items to operate.

 

Universal test machine care

installed

The universal test machine is installed in a clean, dry and homogeneous house, taking into account the possibility of a long long beam bending test on the machine and the possibility of using a mirror extension to test, so the test machine should be left around Enough spare area.

 

take over

In the installation of the main body and the dynamometer connected to the tubing, the tubing should first be washed with diesel, do not leave any impurities in the tube to ensure that the oil in the clean.

It should be noted that the joint washer is complete, if not complete should access the machine with a new gasket installed to prevent high pressure oil leakage.

oil specifications selection introduced

High quality medium viscosity mineral oil should be used in hydraulic drive. The oil must contain water, acid and other mixture, should not be decomposed at ordinary temperature, not thick, and before pouring into the machine, the oil must be filtered. Due to improper oil, will make the valve and oil circuit blockage and the machine may produce vibration, which will affect the normal operation of the test machine.

 

irrigation and oil release

Uncover the dynamometer on the left side of the iron gate, you can see the wire mesh filter, filling the oil through the oil filter into the tank, a poured into the oil about 28 liters to the tank outside the oil Bit indicator shall prevail, the oil specifications used can refer to the oil specifications selection introduced.

Before starting the use of the test machine, must be from the tank to the oil pump tubing in the middle of the installation of the middle of the balloon, the bolt and the pipe into a straight line, that tank and oil pump between the oil flow, such as carved with the pipe When it is closed.

The oil on the left side of the left side of the nozzle can be on the use of the oil according to the decision of the climate, such as the oil began to be mixed when the dirty should not be used when the new oil, want to wipe the bottom of the tank or something fall out First put the net oil, remove the lower left of the dynamometer can be covered, after the need to be good.

 

4. electrical connection

The electrical device of the test machine is equipped with a dynamometer. The magnetic starter is operated by a button and has a small transformer. The input power supply is 380 volts, the output voltage is 6 volts and 6.3 in the upper right side of the dynamometer V small indicator light one.

The test machine factory wiring power supply 380 volts, magnetic starter coil is 380 volts, from the power supply leads, through the dynamometer before the cover connected to the wiring board. All wiring can refer to the manual with the electrical circuit, then Good power and open the fuel tank and the pump access to the bolt, the other parts after the inspection is completed, you can start the dynamometer table on the button, try to run the pump motor to observe the direction of the flywheel rotation and flywheel arrow direction, if not meet should be replaced The power connector to make it the same, and then start the next jaw lift motor, check the next clamp under the action of the lifting of the button is consistent with the text shown on the button, and then check the overtravel and overload button is combined.

 

5. Lubrication

The gland on the main body is provided with an oil filling hole through which the oil is lubricated, and the thread of the lower clamp body is lifted and lowered according to the use condition so as to avoid abrasion.

After the installation of the main body through the base above the oil probe needle hole, with a funnel to the oil tank into the oil, into the oil depth of 30 mm to detect the oil probe.

The ball bearing at both ends of the ball bearing, usually not allowed to try to lubricate the oil, so as not to produce sludge within a long time to prevent the accuracy of the precise mechanism, if the use of a long time must be removed when the internal oil can be washed with a small amount of high-quality lubrication Oil, but enough to prevent its corrosion, installed after a standard dynamometer re-check it.

The pump does not have a screw plug, installed, the first time it will be unscrewed to the pump into a large number of internal oil, such as internal oil due to the use of the course of time is not bad, the pump can be screwed out of the screw out, , If the machine is often used once a month should be changed.


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