Heating device suitable for energetic material performance test and safe temperature control method

Abstract

The invention provides a heating device suitable for energetic material performance testing and a safe temperature control method, and relates to the field of material performance testing. The device mainly comprises a heat insulation shell, a heating module, a heat preservation layer and a temperature controller. The heat insulation shell is used for reducing heat exchange between the heating module and the external environment. The heating module can uniformly heat the to-be-tested sample at different temperatures; the heat preservation layer is arranged between the heat insulation shell and the heating module and is used for reducing heat loss; and the temperature controller is used for setting test conditions, programming a temperature rise gradient, monitoring and performing over-temperature alarm. The device has the advantages of being high in temperature control accuracy, small in temperature fluctuation, capable of working for a long period, high in safety and the like, can be widely applied to stability and aging tests of energetic materials, and can realize uniform heating, accurate temperature control and long-term stable working; the device is especially suitable for vacuum stability tests, methyl violet tests, Vieier tests, accelerated aging tests, differential heat and explosion point tests and the like.

Description

Technical Field

[0001] The present invention relates to the field of material property testing, and particularly to a heating device suitable for testing the properties of energetic materials and a safety temperature control method. Background Art

[0002] In the research, production, and use processes of energetic materials, it is crucial to test their stability and aging properties. Existing technologies usually adopt methods such as traditional socket hole heating and heating plate heating.

[0003] Among them, traditional socket hole heating is the most common heating method in the prior art. A heating tube is installed at the center position of the metal heating module, and there are a certain number of socket holes on the upper surface, into which test tubes containing samples can be inserted to heat the samples. The uniformity of this heating method is poor. The larger the size of the metal heating module, the more obvious the non-uniform heating situation will be. The fundamental reason is that the heating tube is installed at the center position of the heating module, and the heat flows from the center to the socket holes, forming a temperature gradient, that is, the temperature of the central part is the highest, and the farther away from the heating tube, the lower the temperature. This heating method causes the temperature fluctuation range of each socket hole to exceed ±2°C, resulting in uneven heating during the test and poor accuracy of the test results.

[0004] The heating plate heating method heats through embedded electric heating elements. When powered on, the electric heating elements generate heat, causing the surface temperature of the heating plate to rise, thereby achieving the heating effect. Since it uses a surface heating method, this will lead to uneven heating of the specimen, resulting in local overheating of the sample, affecting the accuracy of the test results, and it is also possible for the sample to explode due to local overheating during the test.

[0005] Since a large amount of samples are required for stability and aging tests, 2 - 5 g of explosives need to be added to each socket hole, and a total of up to 50 g of specimens can be placed in 10 socket holes. Therefore, the test safety is particularly important. Especially for the aging test of energetic materials, this type of test usually requires the heating module to work continuously for several weeks or even several months. During the heating process, if the heating module overheats severely, it may cause the samples to be tested to explode directly, resulting in serious consequences. And the existing heating modules have relatively single functions in over-temperature alarm, presenting serious safety hazards.

[0006] Therefore, the present invention aims to propose a new technical solution to make the samples heated evenly, the test results accurate, the test process safe, and the temperature control stable for a long time. Summary of the Invention

[0007] In view of the above problems, the present invention provides a heating device suitable for testing the properties of energetic materials and a safety temperature control method, which can solve the problems of poor heating uniformity, low accuracy of test results, risks in the test process, and poor long-term temperature control stability.

[0008] The technical solution is as follows:

[0009] A heating device and a safety temperature control method applicable to the performance test of energetic materials, characterized by comprising: a heat-insulating outer shell, a heating module, a heat-insulating layer, and a temperature controller.

[0010] The heat-insulating outer shell includes a negative-pressure interlayer, a pressure sensor, and a vacuum pumping interface, which are used to provide good heat-insulating performance and reduce the heat exchange between the heating module and the external environment.

[0011] The negative-pressure interlayer is a double-layer jacket with a hollow structure, and the internal hollow environment is under negative pressure.

[0012] The pressure sensor is installed on the negative-pressure interlayer, and there is a vacuum pumping interface on the jacket. This interface can be externally connected to a vacuum pump and a check valve. The internal environment of the negative-pressure interlayer is evacuated by the vacuum pump to form a vacuum heat-insulating layer, and the check valve is installed to prevent the vacuum pump oil from being sucked back into the negative-pressure interlayer.

[0013] Further explanation, the formation of the vacuum heat-insulating layer can avoid the loss of heat from the heating module to the heat-insulating outer shell. In the present invention, the vacuum degree is set to be from -50 kPa to -60 kPa, and the pressure sensor monitors the vacuum degree in the negative-pressure interlayer in real time. Once the monitored pressure is higher than -50 kPa, the system will automatically start the vacuum pump for vacuum pumping operation. When the vacuum degree drops to about -60 kPa, the vacuum pump stops working.

[0014] After the test is completed, if it is necessary to cool down and turn off the instrument or to reduce the test temperature for another test, the vacuum pump can be disconnected, and the atmosphere environment in the negative-pressure interlayer will reach one atmosphere. In this way, the vacuum heat-insulating function fails, and the heating module cools down rapidly.

[0015] The heating module is made of a metal material and includes a sample seat hole, a heating tube installation hole, a temperature sensor, and an arc-shaped groove, which are used to uniformly heat the test sample at different temperatures.

[0016] There are 10 sample seat holes on the upper end surface of the heating module, and the diameter of the seat hole is 28 mm, which just allows the sample test tube to be inserted; there are 10 heating tube installation holes on the lower end surface, which just allow the heating tube to be inserted. The diameter of the entire heating module reaches 255 mm, and the size is quite large. If the traditional seat hole heating method is used, the uniformity of sample heating will become very poor, and the accuracy of the test results will be reduced.

[0017] Such as Figure 2As shown, there is 1 heating tube beside each sample holder hole, and 10 holder holes correspond to 10 heating tubes. For each holder hole, there are 2 heating tubes on both sides of it to heat it simultaneously. Compared with the way of using 1 or multiple heating tubes to heat from the central position in the whole heating module, the temperature control stability has been significantly improved. Moreover, since the heating tubes are relatively close to the holder holes, the heating rate and efficiency will be greatly increased, avoiding the temperature fluctuations caused by the heat lag of the holder holes due to the temperature gradient.

[0018] The arc-shaped groove is located around the sample holder hole, with a width of 2 - 3 mm and a depth of 100 mm.

[0019] In the above heating method, the inner wall of the holder hole in the middle of the two heating tubes is heated quickly, and the temperature will be slightly higher. And the heating method of the heating tubes belongs to pulse heating, with a heating time base of once per 1 s, which will cause the temperature of the holder hole to fluctuate, reaching ±0.8°C. The present invention designs an arc-shaped groove to avoid the concentrated action of heat and achieve the effect of heat diversion. In this case, the heat flow is mainly divided into 4 strands, allowing the heat to act on the inner wall of the holder hole at the same heat flow gradient and the same rate simultaneously. Finally, the temperature control stability can reach ±0.15°C.

[0020] In order to explore the limit of temperature control, during the research process of the present invention, the number of arc-shaped grooves is changed from 4 to 8. Theoretically, the temperature control stability can be further improved, but actually the temperature control stability still remains at ±0.15°C without obvious change. Therefore, the present invention finally selects the design of 4 arc-shaped grooves, which can not only meet the requirements of temperature control stability but also reduce the complexity of mechanical processing.

[0021] The heat insulation layer is between the heat insulation outer shell and the heating module, filled with heat insulation materials, used to reduce heat dissipation, and has a good heat insulation effect.

[0022] The temperature controller includes: an over-temperature alarm system, a temperature sensor, a data acquisition device, and a temperature controller, used to set test conditions, program the heating gradient, monitor, and give an over-temperature alarm.

[0023] There are a total of 4 temperature sensors. Among them, 2 sensors are connected to the temperature controller for temperature control, and the other 2 sensors are connected to the data acquisition device for reading temperature, to collect the temperature of the heating module in real time and record it. Once one of the temperature control sensors fails, the other sensor connected to the temperature controller immediately takes over the temperature control, or the temperature controller immediately cuts off the heating. This design can avoid the over-temperature risk caused by the failure of the temperature control sensor.

[0024] The temperature controller makes the following analysis and countermeasures for the over-temperature risk during the temperature control process:

[0025] 1) During the heating process, if the output millivolt voltage of the main temperature control sensor suddenly reaches the maximum value, it indicates that the main temperature control sensor is open-circuited with the temperature controller, and the open-circuit alarm is activated. The secondary temperature control sensor immediately takes over the temperature control. If the secondary temperature control sensor also has the same problem, then the temperature controller immediately cuts off the heating.

[0026] 2) The power output curves of the heating module at different heating rates are pre-stored in the system (see Figure 3 ). If, during the heating process, the power output curve of the heating module deviates from the pre-stored curve by more than 15%, it indicates that the temperature sensor may have a problem, resulting in a change in its linearity, or the heating tube may be damaged, resulting in a change in its heating power. The temperature controller cuts off the heating and activates the alarm system, and the touch screen prompts to check the temperature sensor and the heating tube.

[0027] 3) If the deviation between the real-time temperature and the set temperature data of the two temperature sensors connected to the data acquisition device exceeds 5%, it indicates that the temperature sensor may have a problem. The temperature controller cuts off the heating and activates the alarm system, and the touch screen prompts to check the temperature sensor.

[0028] 4) If the real-time temperature of one of these four temperature sensors exceeds the set temperature by more than 5°C, the temperature controller cuts off the heating and activates the alarm system, and the touch screen prompts to check the temperature sensor.

[0029] The beneficial effects brought by the technical solution provided by the present invention at least include:

[0030] 1. The adiabatic shell of the present invention can provide good adiabatic performance, reduce the heat exchange between the heating module and the external environment, improve the temperature control stability of the heating module under long-term constant temperature conditions, ensure the accuracy of test results, and is particularly suitable for long-term stability and aging tests of explosives.

[0031] 2. The seat holes and heating tubes of the heating module of the present invention adopt an adjacent symmetric design, and an arc-shaped groove is designed around the seat holes, so that the heat acts on the inner wall of the seat holes at the same heat flow gradient and rate, ensuring that the samples in the seat holes are evenly heated, improving the accuracy of test results, improving the heating efficiency, and avoiding local overheating caused by uneven heating. It is particularly suitable for testing explosive samples such as explosives.

[0032] 3. The temperature controller of the present invention adopts multiple temperature control methods and establishes a perfect over-temperature monitoring logic, which fundamentally reduces the test risk. Since a large amount of samples are required for the stability and aging tests of explosives, and this type of test usually requires the heating module to work continuously for several weeks or even months, over-temperature is inevitable during long-term heating. The temperature controller of the present invention can effectively avoid over-temperature and ensure the safety of the test process. Description of the Drawings

[0033] Figure 1 Front view of the present invention;

[0034] Figure 2 Bottom view of the present invention;

[0035] Figure 3 It is a preset temperature curve graph.

[0036] Wherein: 1 is an adiabatic housing, 1-1 is a negative pressure interlayer, 1-2 is a vacuum pumping interface, 1-3 is a pressure sensor interface; 2 is a heating module, 2-1 is a sample holder hole, 2-2 is a heating tube mounting hole, 2-3 is a temperature sensor, 2-4 is an arc-shaped groove, 3 is a heat insulation layer, 4 is a temperature controller. Specific embodiments

[0037] The present invention can be embodied in many different forms of embodiments, and the protection scope of the present invention is not limited to the embodiments mentioned in the text.

[0038] As shown in the attached drawings, a heating device and a temperature control method applicable to the stability test of energetic materials include: an adiabatic housing (1), a heating module (2), a heat insulation layer (3) and a temperature controller (4).

[0039] The adiabatic housing includes a negative pressure interlayer (1-1), a vacuum pumping interface (1-2) and a pressure sensor interface (1-3); a pressure sensor and a solenoid valve are installed on a three-way interface on the pressure sensor interface (1-3) of the negative pressure interlayer, and their signal cables are all connected to a data acquisition device, and the pressure data can be displayed on a touch screen or a software interface in real time. A check valve is installed on the vacuum pump and is connected to the vacuum pumping interface (1-2) through a PU hose. The power supply cable of the vacuum pump is connected to the corresponding interface on the temperature controller (4), and the temperature controller (4) controls the opening and closing of the vacuum pump.

[0040] The heating module (2) is made of a metal material and includes a sample holder hole (2-1), a heating tube mounting hole (2-2), a temperature sensor (2-3) and an arc-shaped groove (2-4); there are 10 sample holder holes (2-1) on the upper end surface of the heating module (2), the hole diameter is 28 mm, just enough to accommodate the sample test tube to be inserted, and there are 10 heating tube mounting holes (2-2) on its lower end surface, just enough to accommodate the heating tube to be inserted; the temperature sensors (2-3) are grouped in pairs, with a total of 2 groups, and are fixed on the heating module (2) through M10 thermocouple clamps, and the signal cables are respectively connected to the temperature controller (4-3) of the temperature controller (4) and the data acquisition device (4-4); the arc-shaped groove (2-4) is located around the sample holder hole (2-1), asymmetrically distributed, with a notch width of 2-3 mm and a depth of 100 mm.

[0041] The heat insulation layer (3) is between the adiabatic housing (1) and the heating module (2), filled with heat insulation material, which can minimize heat loss.

[0042] The thermostat (4) analyzes the over-temperature risk during the temperature control process and has the following countermeasures:

[0043] 1) During the heating process, if the output millivolt voltage of the main temperature control sensor suddenly reaches the maximum value, it indicates that the main temperature control sensor is open-circuited with the thermostat, and the open-circuit alarm is activated. The slave temperature control sensor immediately takes over the temperature control. If the same problem occurs with the slave temperature control sensor, the thermostat immediately cuts off the heating.

[0044] 2) The power output curves of the heating module at different heating rates are pre-stored in the system (see Figure 3 ). During the heating process, if the deviation between the power output curve of the heating module and the pre-stored curve exceeds 15%, it indicates that the temperature sensor may have problems resulting in a change in its linearity, or the heating tube has suffered losses, resulting in a change in its heating power. The thermostat cuts off the heating and activates the alarm system, and the touch screen prompts to check the temperature sensor and the heating tube.

[0045] 3) If the deviation between the real-time temperature and the set temperature data of the two temperature sensors connected to the data acquisition device exceeds 5%, it indicates that the temperature sensor may have problems. The thermostat cuts off the heating and activates the alarm system, and the touch screen prompts to check the temperature sensor.

[0046] 4) If the real-time temperature of one of the four temperature sensors exceeds the set temperature by more than 5°C, the thermostat cuts off the heating and activates the alarm system, and the touch screen prompts to check the temperature sensor.

[0047] The heating device and temperature control method suitable for the stability test of energetic materials provided in the present invention mainly conduct the stability and aging performance tests of energetic materials. The specific operation steps are as follows:

[0048] 1. Set the target temperature. Turn on the machine and set the test temperature heating rate, test stop temperature, and test stop time.

[0049] 2. Set the alarm conditions. Set the alarm trigger conditions for the thermostat and the acquisition device on the software.

[0050] 3. Load the sample. Add the quartz test tube or metal test tube containing the test sample into the sample seat hole (2-1) of the heating module.

[0051] 4. Prepare a negative pressure environment for the adiabatic enclosure. Connect the signal cable of the pressure sensor to the thermostat (4), install a check valve on the vacuum pump, connect it to the vacuum interface (1-2) through a PU hose, and control the opening and closing of the vacuum pump by the thermostat (4).

[0052] 5. Start the heating program. Remotely start the heating program using the supporting software. The thermostat (4) operates according to the set test conditions. The real-time temperature curves of all sensors can be remotely viewed using the supporting software.

[0053] 6. During the test. The stability or aging test of the propellant explosive usually takes several days or months. It is required that the operator check whether there are any abnormalities in the real-time temperature curve at least every 10 hours and check whether the negative pressure in the negative pressure interlayer (1-1) meets the set conditions. Personnel are prohibited from approaching the heating module (2) during the test.

[0054] 7. Alarm triggered. Once the thermostat (4) gives an alarm, the buzzer will sound continuously to remind the operator to check the test. The operator cannot approach the heating module (2). The heating can be remotely cut off using the software. It is only allowed to check closely after the temperature of the heating module (2) drops to room temperature.

[0055] 8. Test completed. After the test is completed, the thermostat (4) will automatically turn off the heating and the vacuum pump. The solenoid valve on the vacuum interface (1-2) will open to let air into the negative pressure interlayer (1-1) to achieve rapid cooling.

[0056] 9. Shut down. After the heating module has cooled to room temperature, the sample tube can be removed from the sample seat hole (2-1). Clean the instrument after shutting down.

Claims

1. A heating device and a safe temperature control method suitable for energetic material performance testing, characterized in that: The device mainly comprises: a heat-insulating shell (1), a heating module (2), a heat-insulating layer (3) and a temperature controller (4); The heat-insulating housing (1) is used to provide good heat-insulating performance and reduce heat exchange between the heating module and the external environment; The heating module (2) is used to uniformly heat the sample to be tested at different temperatures; The thermal insulation layer (3) is filled with thermal insulation material between the thermal insulation shell (1) and the heating module (2) to reduce heat loss; The temperature controller (4) is used to set test conditions, program temperature gradients, monitor and alarm for over-temperature.

2. The heating device and safe temperature control method suitable for energetic material performance testing according to claim 1, characterized in that: The thermal insulation shell (1) comprises: a negative pressure interlayer (1-1), a vacuum extraction interface (1-2) and a pressure sensor interface (1-3).

3. The heating device and safe temperature control method suitable for energetic material performance testing according to claim 2, characterized in that: The negative pressure interlayer (1-1) is a double-layer jacket with a hollow structure, and the hollow environment is negative pressure.

4. The heating device and safe temperature control method suitable for energetic material performance testing according to claim 1, characterized in that: Each seat hole of the heating module (2) is provided with four arc-shaped grooves (2-4) around it for heat distribution.

5. The heating device and temperature control method for energetic material stability testing according to claim 1, characterized in that: The temperature controller (4) analyzes, determines and responds to the over-temperature risk during the temperature control process as follows: 1) During heating, if the output millivolt voltage of the main temperature control sensor suddenly reaches the maximum value, it is determined that the main temperature control sensor and the temperature controller are disconnected, the open circuit alarm is activated, and the secondary temperature control sensor immediately takes over the temperature control. If the secondary temperature control sensor also has the same problem, the temperature controller immediately cuts off the heating; 2) During heating, if the power output curve of the heating module deviates from the pre-stored curve by more than 15%, it is determined that there may be a problem with the temperature sensor, resulting in a change in its linearity or a loss in the heating tube, resulting in a change in its heating power. The temperature controller cuts off the heating and activates the alarm system, and the touch screen prompts to check the temperature sensor and the heating tube; 3) If the real-time temperature of the two temperature sensors connected to the data acquisition device deviates from the set temperature data by more than 5%, it indicates that there may be a problem with the temperature sensor. The temperature controller cuts off the heating and activates the alarm system, and the touch screen prompts to check the temperature sensor; 4) If the real-time temperature of one of the four temperature sensors exceeds the set temperature by more than 5°C, the thermostat cuts off the heating and activates the alarm system, and the touch screen prompts to check the temperature sensor.

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