How to distinguish superior and inferior products of universal tensile testing machine?

Universal tensile testing machine is suitable for testing various physical and mechanical properties of plastic sheet, pipe, profile, plastic film, rubber, wire and cable. It is an indispensable testing equipment for material development, physical property test, teaching research, quality control and so on. As an important part of the instrument, the fixture of Yuanfeng tensile testing machine needs different fixtures for different materials, which is also a test equipment Whether it can be carried out smoothly and the accuracy of test results is an important factor.

1. Software and hardware: the high-quality tensile testing machine adopts brand computer, and the control system software is Windows XP operating system platform, which has the characteristics of fast running speed, mild interface, simple operation, etc. it can meet the test and measurement needs of different materials, and can measure the physical properties of various materials according to national standards, international standards or industry standards.

2. Ball screw: there are ball screw and trapezoidal screw currently used in tensile testing machine. Generally speaking, the trapezoidal lead screw has large clearance, large friction force and short service life. At present, some manufacturers in the market will use trapezoidal screw instead of ball screw in order to save costs and obtain greater profits.

3. Motor: high quality tensile testing machine motor adopts AC servo speed control system, Panasonic AC servo motor, stable and reliable performance, transformer test has over-current, over-voltage, overload and other protection devices. At present, there is also an electronic universal testing machine on the market, which adopts ordinary three-phase motor or variable-frequency motor. This motor adopts analog signal control, with slow control response and inaccurate positioning. Generally, the speed range is narrow. If there is high speed, there is no low speed, or if there is low speed, there is no high speed, and the speed control is not accurate.

4. Sensor: the sensor is an important part of the accuracy and force stability of the tensile testing machine. At present, the types of sensors on the market are S-type and spoke type. The accuracy of the sensor is affected by the poor accuracy of the internal resistance strain gauge, the poor aging resistance of the adhesive used in the fixed strain gauge, and the poor material of the sensor.

5. Transmission system: there are mainly two kinds of transmission part of tensile testing machine: one is arc synchronous gear belt, precision screw drive; the other is ordinary belt drive. The first transmission mode has stable transmission, low noise, high transmission efficiency, high precision and long service life. The second transmission mode can not guarantee the synchronization of the transmission, so the accuracy and stability are not as good as the first transmission system.

Purchase of tensile testing machine:

1. The first consideration should be given to the range of material tension to be tested.

The range of pulling force determines the sensor used and the structure of the pulling machine, but it has little effect on the price (except the door type). For general flexible packaging manufacturers, the tension range of 100 Newton is enough. Therefore, it is also decided to adopt the single arm type. The structure corresponding to the single arm type is the door type structure, which is suitable for relatively large pulling force, such as one ton or more. So flexible packaging manufacturers basically do not need.

2. The problem of test travel.

According to the needs of flexible packaging film, test performance and requirements, the stroke can be 600-1500mm. If the material elongation exceeds 1000%, the stroke can be 1000 or 1200mm.

3. Standard configuration problem.

There are three basic configurations of intelligence: host, microcomputer and printer. If the microcomputer has strong function, it can print directly. In addition, it can also be equipped with ordinary computer. With the help of computers, complex data analysis can be carried out, such as data editing, partial amplification, report format adjustment, and group style statistical analysis. If equipped with a computer, the manufacturer should add the corresponding control system.

4. Output results.

The output results of test results can be set arbitrarily: maximum force value, elongation, tensile strength, constant force elongation, constant elongation force value, yield strength, elastic modulus and maximum test force. This can be said to be the most comprehensive result of microcomputer operation. The products of some foreign manufacturers can generally export these 8 items. Some domestic manufacturers can output 5-6 items, while others can only output the maximum force value, average value and minimum value.

5. In the experimental project.

Flexible packaging requires a multi-purpose pulling machine, that is, on the basis of different fixtures, it can be used for stretching, compression, bending, tearing, shearing, 180 degree peeling and 90 degree peeling tests. In addition to the above items, there are some high-end tensile machines on the market, which can also test the friction coefficient because of their high sensor accuracy (some up to 1.350000 times).

6. Main mechanical configuration of the product:

There are screw drive and rack drive. The former is expensive for high precision and high repeatability; the latter is cheap for low precision and low repeatability. Lead screw plays a decisive role in the measurement of tension accuracy. General ball screw, trapezoidal screw, general screw. Among them, the ball screw has the highest accuracy, but its performance depends on the operation of the computer servo system, and the price of the whole set is relatively expensive. Using general lead screw and trapezoidal lead screw can achieve the required accuracy of soft packaging, that is, 0.1-1% accuracy. Transmission, there are gear transmission and chain transmission, the former is expensive, for high precision; the latter is cheap, for low precision. Sensor, the main cost is life, photoelectric induction is one of the more advanced technology, generally more than 100000 times, import and domestic joint venture manufacturers can achieve better technology is Jiangdu Tianyuan test Machinery Co., Ltd

7. Test speed.

Some of the market equipment is in the range of 10 ~ 500 mm / min, and some in the range of 0.001 ~ 500 mm / min. the former generally uses the ordinary speed control system, which has low cost and rough influence on the accuracy; the latter uses the servo system, which is expensive and has high accuracy. For soft packaging enterprises, the servo system with speed range of 1 ~ 500 mm / min is enough, so that it does not affect the accuracy and the price is within the reasonable range.

8. Measurement accuracy.

The accuracy includes force measurement accuracy, velocity accuracy, deformation accuracy and displacement accuracy. These precision values can reach up to plus or minus 0.5. But for general manufacturers, 1% accuracy is enough. In addition, the force resolution can almost reach 400000.