SU949453A1 - Thermoelectric device for checking metals and alloys - Google Patents

Description

The invention relates to the field of non-destructive control, namely, devices designed to determine the chemical composition and structure of metals and alloys by the value of thermoEMF and can be used in the metallurgical and engineering industries to control product quality.

A thermoelectric device for monitoring metals and alloys is known, which contains two electrodes, one of which is heated by a heater, and measuring device 1,

A disadvantage of this device is the dependence of the temperature difference between the cold and hot electrodes on the ambient temperature and on the temperature fluctuations of the cold electrode, which leads to a change in the thermo-emf in the measuring circuit and a decrease in the measurement accuracy. The same result is caused by the temperature fluctuations that are uncontrolled in the process of operation at the junctions of the electrodes with the wires.

The closest technical solution to the invention is a thermoelectric device for controlling metals and alloys, containing

cold and hot electrodes, a heating element located on the hot electrode, a thermometer meter connected to the connecting wires, and a differential thermocouple connected between the hot and cold electrodes and connected to the thermal control circuit. The thermoregulation scheme maintains between 10 electrodes a constant temperature difference, which increases the measurement accuracy, influencing the measurement result of random thermo-emf arising from temperature differences.

15 at the joints of dissimilar metals, eliminated by making electrodes and connecting wires of the same material 2J. However, the connection of the contacts of the thermal sensor (thermocouple junctions) with the electrodes makes it difficult to move them during operation — and thus has an effect on the degree of clamping between electrodes and controlled

25 product. The branches of the thermocouple themselves under the movement of the electrodes are subjected to mechanical loads and can fail. When moving the electrodes, as well as replacing them can

Claims (2)

30 changes the conditions of heat transfer at the points of contact, which leads to a violation of temperature control. Ultimately, the reliability of the device and measurement accuracy are reduced. The purpose of the invention is to improve the reliability of the device and measurement accuracy. The goal is achieved by the fact that in a thermoelectric device for controlling metals and alloys, containing two electrodes, a heating element connected to a thermo-EMF meter, a differential thermocouple and a thermoregulation circuit connected to the heating element and thermocouple, the electrodes are placed in separate metal blocks to which thermocouple junctions, and the junction of the electrode and thermocouple are placed in a metal block, separate from the first two, at. This heating element is inserted inside one of the blocks of electrodes. The drawing shows a diagram of the proposed device. The device contains electrodes 1 and 2, covered with electrically insulated and electrically insulated into metal blocks 3 and 4. The electrodes are connected by wires to the meter 5 of the thermo-emf. The blocks of the differential thermocouple 6 are connected to blocks 3 and 4. The ends of the thermocouple are connected via wires to the thermal regulation circuit 7, to which the heating element 8 located in the metal block 4 is also connected. The electrodes and TepMoriapbi are electrically insulated and placed in the metal block 9. Blocks 3, 4, and 8 are fixed in the housing 10. The electrodes are spring-loaded with springs 11. The device operates as follows. The heating element 8 preheats the metal block 4. Thermocouple 6 supplies to the thermal regulation circuit 7 an emf proportional to the temperature difference between blocks 3 and 4. In this case, the thermoregulation circuit sets the operation mode of the heating element at which between blocks 3 and 4 and, consequently, between the electrodes 1 and 2 placed in them, a constant predetermined temperature difference is maintained. The device is pressed by the ends of the electrodes 1 and 2 to the surface of the controlled product while the electrodes move in blocks 3, 4 and 9 and after the body 10 rests on the surface of the product, constant contact with the product is obtained, supported by springs 11. The thermo-EMF meter 5 - EMF, which is judged by the chemical composition of the controlled product In the proposed device, the thermocouple is not subjected to mechanical loads and does not interfere with the movement of the electrodes, it has a constant thermal conductivity. tact with blocks 3 and 4. and maintains a constant temperature difference between them. This contact also does not change when the electrode is replaced. Due to the high thermal conductivity of the metal block 9, the same temperature is created at the junction of the electrodes with the wires. At the same time, the temperature of unit 9 can be any (for example, follow room temperature changes) - the thermo-emf arising in the joints, caused by the difference in the metals in contact, are always directed towards each other and are mutually compensated. Placing a heating element inside a heated block increases its efficiency and reduces the heating of surrounding parts by dissipating heat. The replacement time of the heating element is determined by seconds, which allows for continuity of operation of the device. Thus, the increased reliability of the device and measurement accuracy. In this case, it is also possible to achieve such advantages as size reduction, the ability to perform the device in the form of a remote sensor operating in a stable temperature mode and connected with it by a cable of a thermoregulation unit and measurement of thermo-emf. Simplified maintenance and repair. A thermoelectric device for monitoring metals and alloys, comprising two electrodes connected to a thermo-EMF meter, a heating element, a differential thermocouple, and a thermal control circuit that is different from the heating element and the thermocouple. In order to improve device reliability and measurement accuracy, the electrodes are placed into separate metal blocks to which the junctions of the thermocouple are connected, and the junction points of the electrodes and the thermocouple are placed into a metal block separate from the first two, while the heating element is inserted inside one of the electrode blocks. Sources of information taken into account during the examination 1. Akimov G., V., Pevzner L.Ye. Thermoelectric method of steel grading. Factory Laboratory, 1939, VIII, p. 1273. 2. USSR author's certificate No. 345426, cl. C 01 N 27/14, 1969 (prototype).