Analyses based on the workpiece temperature on heat preservation heat treatment technique of thermocouple

Abstract: in the heat treatment of workpiece, are generally go through the process of heating, heat preservation, cooling, the thermal insulation is the second step in the heat treatment process, also is an important part. At this time must be able to accurately monitor the key technical parameters of the workpiece heat treatment, in order to accurately control process, to prevent the workpiece is unqualified, meet the expected requirements of heat treatment.

the merits of the heat treatment process directly affect the work performance is good or bad, if you want to make a reasonable heat treatment process system, not only need theory knowledge as the basis, should also be combined with the actual production situation to optimize adjustment.

in impeller heat treatment, for example, based on thermal insulation technology of workpiece surface temperature can be accurately detected workpiece temperature changes in the process of heating, and combining with the furnace sample ring mechanics performance reports, science to develop a system of heat treatment process, used to real-time monitor the heat treatment process, improve the quality of heat treatment, the performance of components conform to the technical requirements.

1。 Technology application background

at present, our country most of the heat treatment of domestic enterprises on remains to be improved and improving heat treatment process, such as the workpiece heat insulation timing is based on the temperature of the heat treatment furnace, if there exists large volume of heat treatment furnace and furnace temperature during the process of heating and heat preservation of many factors such as uneven, furnace temperature actually does not reflect the actual temperature of workpiece. Work-piece temperature lags behind the furnace temperature, the actual temperature less than the temperature of constant temperature time. In the actual production in furnace temperature and workpiece temperature there is a larger temperature difference. Therefore, if as heat treatment furnace temperature holding time on the basis of is flawed.

2。 ” Heat preservation & throughout; The definition of

countries & other; Five-year & throughout; Planning of textbooks for heat treatment of heat preservation is defined as: & other; For large or furnace charging quantity is large, need to determine the mean temperature and heat preservation time, respectively. Bulk both temperature and time on the meter to the temperature in the production to the workpiece surface integral color uniform and the time needed for the same as the wall color; Refers to the time of heat preservation to maintain constant temperature time used ever since. For small and medium-sized pieces, basic can do the core and surface of synchronization to heat up, therefore, generally don't have to be calculated separately; When the furnace charging is, after the furnace temperature to the temperature time is the time of heat preservation. The heat preservation time commonly used T = akD is calculated. ”

in the latest national standard GB / 7232 & ndash; 2012 in terms of metal heat treatment process, definition of insulation: & other; Artifacts or heating medium in the process of temperature keeping a certain time of operation, the constant temperature constant temperature keeping time and temperature respectively according to the time of heat preservation and thermal insulation temperature. ” So based on workpiece surface temperature of heat preservation heat treatment is feasible.

so far, the holding time is not a reliable and accurate calculation method, generally by the test and production experience to determine the reasonable temperature. This article tells the story of based on real-time monitoring of the workpiece surface temperature in the heat treatment process of operation.

3。 Practical application

in the actual process of heat treatment heating and temperature measurement system is used to real-time monitor the temperature of the workpiece in different positions, and analyzes the temperature of the temperature control instrument to collect, to draw the workpiece in the actual temperature data and temperature - in the process of heat treatment Time curve, can more accurately determine the heat preservation time, workpiece cooling time, according to the state to develop more specification of the heat treatment process.

1) Temperature measuring system, the selection of temperature measuring system is: the temperature measuring element instrument ( Nickel chrome & ndash; Nickel silicon thermocouple) , intelligent temperature control instrument, and other connecting parts. One end of the thermocouple connection intelligent temperature controller, the other end of the contact inside the closed impeller, as shown in figure 1.

the symmetric, impeller and the thermocouple measurements for two root, respectively, on both sides of impeller. The thermocouple in the distribution of the impeller shows that heat treatment is shown in figure 2.

( 2) Heat treatment of solid solution + aging heat treatment application process, heat treatment process as shown in table 1. Figure 3 for an impeller of workpiece heating process of the solid solution temperature - Time curve; Figure 4 - for impeller of workpiece heating process of the aging temperature Time curve. Due to the small sample, heating up fast, so don't give too much analysis, two temperature measuring point can be seen from the figure despite local heating speed, but in general is conform to the trend of unification, uneven heating obviously is caused by the uneven temperature in the furnace. In order to make any part of the workpiece, especially the core area can achieve full of Mr Obama's body and the requirement of the equalization of the workpiece to set temperature insulation again after the proper time.

( 3) Inspection analysis of solid solution + performance analysis of the workpiece after aging heat treatment. Figure 5 for the test report home page; Table 2 for related mechanical properties report data. Performance test report showed that the impeller heat treatment to achieve requirements, meet the use performance of the workpiece.

4。 Conclusion

( 1) Application of the technology can be real-time monitoring of the workpiece in the process of heat treatment temperature, provides reference for later workpiece heat treatment process.

( 2) Based on mechanics performance test, the application of the technology to meet the workpiece using performance requirements. The technology in other artifacts can also be applied in the field of heat treatment.

( 3) Optimization process, original process parameters accurately, saving the unnecessary energy consumption.

( 4) If the timing of furnace temperature heat preservation, heat treatment for different size of workpiece to be effective thickness calculation or test many times to get the right time to process, so the application of this technology can greatly solve the problem.