1、 Execution standards

According to the equipment design and manufacturing, the acceptance of various indicators of the thermal vacuum test chamber should comply with GB/T32221-2015 "General Technical Conditions for Vacuum Thermal Environment Simulation Test Equipment for Spacecraft", QJ20126-2012 "Vacuum Container Specification for Spacecraft Space Environment Simulation Test Equipment", and QJ20127-2012 "Technical Requirements for Spacecraft Space Thermal Environment Test Equipment". The inspection tools and gauges required for final acceptance shall be provided free of charge by Party B. Any matters not covered shall be accepted in accordance with the national standard GJB-150 "Environmental Test Methods for Military Equipment".

2、 The purpose and characteristics of the equipment

This device is mainly used for High and low temperature tests, low-pressure discharge tests under high vacuum conditions on the lunar surface, and can also be used as a simulation test device for other small components in orbit.

This technical solution is one of the basis for designing and manufacturing the equipment. This equipment includes five aspects: thermal vacuum simulation container, vacuum protection system, high and low temperature protection system, thermal vacuum state control and display system, and auxiliary supporting system. The equipment developed based on this technical solution can truly simulate the cold and hot environment of a vacuum space, and can effectively control, monitor, and record the vacuum degree and temperature of the space. The device has the following characteristics.

The entire equipment vacuum system adopts a low-temperature pump as the main pump, with a screw dry pump as the front stage and pre pumping pump, which can achieve the required working vacuum degree for oil-free testing; In terms of temperature control, mechanical refrigeration is used to obtain a low-temperature background, and an intelligent PID temperature controller is used to control the heating current of the heating cage, thereby accurately controlling the temperature; The acquisition of low temperature adopts a unique mechanical refrigeration technology, which eliminates the cost of using liquid nitrogen refrigeration. The control system adopts a combination of industrial computer and PLC for joint control. The display interface of the industrial computer is clear and easy to understand, the PLC control is accurate and reliable, and the fault diagnosis is simple. In addition, different temperature curve formulas can be made according to the user's process requirements, stored in the industrial computer, and available for users to choose and call during the experiment, making it easy for users to master when conducting experimental operations. In summary, this equipment has high vacuum degree, easy temperature control and good uniformity, stable and reliable long-term operation, and can work continuously for more than 30 days. It is easy and convenient to operate and use. This device has certain specificity and universality, and is an essential equipment for space environment simulation experiments.

3、 Main technical indicators of the equipment system

(1) Internal dimensions of heat sink: φ 1000X1000mm (straight section)

(2) Vacuum box bracket: Bearing capacity: ≥ 60kg, the platform is sliding, with dimensions of 950mm in length and 700mm in width;

(3) Vacuum chamber size: φ 1100X1100mm (straight section)

(4) Ultimate no-load vacuum degree: ≤ 5X10-5Pa，

(5) Empty load vacuum degree:< 1X10-4Pa (room temperature) (arrived within 4 hours after opening the plug valve)

(6) Load vacuum degree ≤ 5X10-4Pa,

(7) Vacuum pumping rate: at room temperature inside the cabin, from atmospheric pressure to 20pa for no less than 10 minutes,

From atmospheric pressure to 5X10-4Pa, with a load of ≤ 150min

(8) Test temperature range: -70 ℃ to+150 ℃ (mechanical refrigeration+infrared heating cage)

(9) Temperature change rate: ≥ 1 ℃/min (rate of change measured on the acceptance specimen)

Average temperature rise from -70 ℃ to+85 ℃ throughout the entire process

Cooling average from+85 ℃ to -70 ℃ throughout the entire process

(10) Test piece heating power:

(11) Temperature uniformity: ± 3 ℃ (under stable temperature and vacuum conditions)

(12) Temperature control accuracy: ± 1 ℃ (measured under stable temperature)

(13) Temperature control method: PLC and manual coexist, all operations are implemented on the computer, with automatic instructions from the central computer, automatic display, automatic monitoring, automatic alarm and protection for branch circuits, and automatic fault diagnosis function. The industrial computer module management system has corresponding interlocking devices and can be programmed for temperature cycling tests.

(14) Temperature control points: a total of 20 (including 1 control point and 19 measurement points)

(15) Pollution analysis: Use a microbalance to test the amount of pollution. The frequency of the balance is 20MHz.

(16) Residual gas analysis: Monitor residual gases inside the container using a quadrupole mass spectrometer. Quality range: 200 quality quantity, H200M (Yingfukang Company)

(17) Low pressure discharge conditions: pressure maintenance can be achieved at a vacuum range of 1.33Pa and atmospheric pressure.

(18) Equipment noise: ≤ 75dB (1.5 meters from the ground and 1 meter from the controller) pre acceptance is tested on site

4、 Equipment configuration requirements

(1) Equipment configuration: All necessary peripherals (circulating water machine, air source, various flanges, etc.) need to be fully equipped

(2) Extraction system:

A main molecular pump: 3600L/s

B Pre stage pump: Vacuum pump from Germany Laibao or Beiyi Youcheng,

(German Leybold has a 5-month warranty and a 1-year warranty, while Beiyi Youcheng has a 3-month warranty and a 2-year warranty, optional)

(4) Vacuum measurement system: choose high-quality Pirani, ionization gauge, and digital vacuum gauge from China

(5) Heating and cooling system: Adopting a new technology of imported refrigeration water-cooled compressor unit, PID temperature control regulation is used, and a stable and reliable temperature control method is adopted, namely mechanical refrigeration+thermal cage temperature control. All other refrigeration system components are of good quality.

(6) Heat sink structure: Made of copper or stainless steel with minimal air release, and with uniform temperature distribution in the heat sink.

(7) Vacuum chamber: Stainless steel 1Cr18Ni9Ti or other better performing stainless steel should be used, and 8mm is recommended.

(8) Observation window: The main door has a 200mm observation window directly.

(9) Internal lighting: 100W

(10) Vacuum flange: Multiple 240mm flanges are opened on both sides of the container.

(11) Measurement location: Pirani and ionization gauge are installed at the front of the container.

(12) Container support plate: The size of the support plate should be as large as possible, and the stress point of the support plate should be on the tank body. The cold plate can be leveled.

(13) General control system: This equipment is a fully automatic control system.

(14) Equipment features: This equipment is a horizontal pure oil-free high vacuum system.

(15) Install a mechanical cold trap at the pumping port of the molecular pump (the molecular pump is only used under special conditions).

5、 Functional requirements for control management and data acquisition system

(1) Control management

Managed through PLC, the PC automatically controls the test of the tested object (can be programmed to perform temperature cycling tests). All working states of the vacuum subsystem, temperature cycling system, container re pressure, water circulation system, measurement system, etc. are controlled and managed, and there is a manual control system that is independent of the computer. Its functions are as follows:

Display the segmented curve of the test sample and the specific position of the current test throughout the entire process on the screen, with printing function.

Real time display of the working status of each component of the vacuum subsystem on the screen, overlaid with the vacuum degree obtained from data acquisition, and equipped with printing function.

Real time display of operating functions such as vacuum pump dry pump, molecular pump, gate valve, vent valve, low-temperature regeneration, ionization gauge baking, etc. on the screen.

Real time display of various parameters and curves of the cryogenic pump on the screen.

Real time display of various operational events on the screen, with safety protection measures such as subsystem fault alarm display and horn sounding.

It can achieve both vacuum testing and vacuum temperature composite testing, and both vacuum and temperature can be controlled by fixed values. It can automatically record temperature and vacuum values as required, and form graphics automatically. It is equipped with a USB interface for exporting data in Excel file format.

(2) Data collection

Equipped with 30 Pt-100 temperature sensors, the sensors can freely switch and control the heat sink and specimen temperature during the experiment.

The equipment control adopts an automatic control program.

40 plug-in columns are required, with a current of 10A.

The Y-27 connector has a total of 300 pins.

Real time collection, display of vacuum degree in the vacuum container and other locations of the vacuum subsystem, and overlay on the working condition map, with printing function.

Real time collection, display of temperature at different measuring points of the test sample, with printing function.

It has storage and printing functions for various pressures and temperatures that have occurred.

Real time display and output of dynamic curves of pollution and residual gas levels.

The software has independent intellectual property rights and is free to upgrade and maintain for life.

6、 Equipment composition design

1. The equipment mainly consists of the following parts:

(1) Vacuum simulation container (vacuum chamber and internal support)

(2) Vacuum protection system (vacuum pump, valve, pipeline, and vacuum measurement)

(3) Temperature protection system:

Low temperature refrigeration system: (Area temperature control refrigeration unit, heat sink, low-temperature valve and connecting pipe)

Heating and temperature control system: (heating cage, heating power supply)

(4) Control and monitoring system (cabinet, industrial computer, PLC).

(5) Auxiliary supporting systems (air pump, cooling circulating water machine, pollution monitoring)

7、 Technical content of equipment subsystem:

1. Vacuum simulation container

1.1 Structural form of vacuum container: horizontal cylindrical body, support frame directly landing, rear end with head welded to the body, front end with head gate.

1.2 Vacuum container material: Stainless steel 304, with a wall thickness of not less than 8mm.

1.3 Vacuum container size: φ 1100X1100mm (straight section size).

1.4 Vacuum container center to ground height: 1500mm

Install a heat sink inside the 1.5 cylinder, and install a heating cage inside the heat sink. The heating cage has guide rails and a test piece platform.

1.6 The gate flange is sealed with a low gas release rate fluororubber ring.

1.7 The container has good grounding, with a ground resistance of ≤ 0.1 Ω.

There is a glass observation window (with a diameter of 240) installed at the center of the entrance.

Above the cylinder, there are high and low vacuum measurements, thin film gauges, and two large flanges (diameter).

Install low-voltage 12V lighting fixtures and corresponding sealed joints (diameter) above the 1.10 container.

1.11 Install a sealed joint (diameter) of temperature sensor PT100 above the container.

There are two flanges (diameter 240, flange) on each side of the 1.12 cylinder for connecting test products.

The rear head of the 1.15 cylinder is equipped with two inlet and outlet main pipeline connection flanges (with a diameter of φ 150 and flanges) for heat sinks.

The rear head of the 1.16 cylinder is also equipped with a heating cage electrode lead connection flange (diameter of φ 150, flange)

The rear head of the 1.17 cylinder is equipped with an electrically operated gate valve of corresponding caliber and a 3600 liter/second pumping molecular pump (with a diameter of 400 and flange).

The rear head of the 1.18 cylinder is equipped with a flange (diameter φ 500) that connects to the low-temperature pump plug valve

Install the connecting flange (with a diameter of 100) of the pre extraction pipeline pre extraction valve at the appropriate position on the cylinder.

1.20 Install the connecting flange (KF40) of the vent valve at the appropriate position on the cylinder body

8、 Vacuum protection system

1. Vacuum pump

1.1 Main vacuum pump: a vacuum pump that reaches the maximum vacuum degree in the vacuum chamber, using domestically produced products, model: pumping speed 3600L/s

1.2 Auxiliary vacuum pump: a vacuum pump used to achieve a certain level of vacuum in the vacuum chamber, using * * company's mechanical pump, model: pumping speed 9L/s

2. Pipeline

All pipes are made of stainless steel metal, and some connections are made of stainless steel metal corrugated pipes.

3. Vacuum measurement

3.1 Film Gauge # 1: Full pressure low vacuum measurement, range 105Pa~102Pa, product of Shanghai Zhentai Instrument and Meter Company.

3.2 Resistance gauge: used to measure the low vacuum degree of the vacuum chamber, with a range of 105Pa~100Pa, a product of Chengdu Zhenghua Instrument and Meter Company.

3.3 Ionization gauge: used to measure the high vacuum degree of the vacuum chamber, with a range of 100Pa~10-5Pa, a product of Chengdu Instrument and Meter Company.

3.4 B-A gauge: Used to measure the ultra-high vacuum degree of vacuum chambers, ranging from 10-2Pa to 10-7Pa, a product of the Radio Department of Peking University.

4. Underframe

Connect the vacuum container with it, fix it directly on the ground, and make reasonable connections with other systems.

9、 Temperature guarantee system

The temperature guarantee system is divided into low-temperature heat sink, high-temperature heating system, and temperature control system

1. Low temperature system

Low temperature refrigeration unit: using German Bitzer compressor, CASCade mechanical refrigeration compressor unit, PID temperature control regulation, stable and reliable refrigeration method, and imported component refrigeration unit. To achieve the lowest background temperature for the heat sink, this low-temperature refrigeration unit has many advantages such as low cooling temperature, low power consumption, easy use, and reliable performance

This article is a technical proposal for a thermal vacuum test equipment (mechanical refrigeration), which is designed and written based on the proposed technical requirements for the thermal vacuum test equipment (mechanical refrigeration). The equipment is mainly used for high and low temperature tests under high vacuum conditions on the lunar surface. This plan extracts the technical requirements and other requirements for the thermal vacuum test equipment (mechanical refrigeration), provides our design for the equipment composition and related equipment technical content, and puts forward requirements for the equipment's usage conditions. In addition, it also clarifies some other content related to equipment support. It is one of the original documents for designing and manufacturing the equipment, and also one of the references for equipment delivery and acceptance.

Oil free vacuum system high and low temperature system control monitoring system

2. High temperature heating and temperature control system

The use of a power regulation module with technology, a temperature control instrument with PID self-tuning, and a heating cage with resistance heating method results in higher temperature control accuracy and greater safety factor. The temperature control system mainly controls the test temperature of the product through automatic temperature control instruments and temperature sensors.

The heating control part includes a heating cage, a vacuum sealed heating electrode, a transformer, a voltage regulating module, and a temperature control box

10、 Heat sink system

The main heat sink tube is made of copper plate and copper tube, with a ribbed coil structure. The outer surface is coated with bright nickel and the inner surface is coated with F26 special black paint. The heat sink is placed in a vacuum container to provide a cold black background for product testing. There are support frames and work platforms installed inside the container. The support frame passes through the heat sink and is fixed on the vacuum chamber shell.

1. Heat sink structure form: rib coil type

2. Effective size of heat sink: φ1000X1000mm;

3. Heat sink material: purple copper;

4. Working environment of heat sink: vacuum state

5. Heat sink bearing internal pressure:> 1.3Mpa

6. Total leakage rate of heat sink:< 5X10-10 Pam3/s

7. Absorption rate of the inner surface of the heat sink:> 0.90;

8. Inner surface of heat sink: coated with black paint F26;

9. Heat sink outer surface: bright nickel plating

10. Minimum temperature of heat sink wall:- 70℃

11. Gate heat sink: The gate is equipped with a heat sink to ensure temperature uniformity. The refrigeration unit provides refrigerant separately.

12. Workpiece mounting plate: used to fix workpieces. The installation board can be freely pushed in and out.

13. The workpiece mounting plate has fixing means to prevent the workpiece from vibrating and causing the mounting plate to move during operation. The size of the installation board is to be determined, with a load-bearing capacity of 100kg.

14. Connecting pipe: The external connecting pipe is made of copper pipe and connected by a bell mouth connection method. The internal connecting pipe is protected by a metal mesh corrugated pipe and sealed with a VCR type structure. Externally wrapped with polyethylene insulation pipe, with minimal cooling loss and no frost formation on the outside.

11、 Monitoring system

1. Auxiliary system

The auxiliary system includes air pump, cooling circulating water machine, overheating, etc.

2. Air pump

Provide original power for vacuum valves. (4~6kg/cm2) Low noise air compressor or other air source.

3. Cooling circulating water machine

Cooling molecular pumps and refrigeration units to save water resources. One vacuum unit and one refrigeration unit are used.