416
12 Integration and Assembly Technology of Lunar Lander
cylinder through the lug. The structure of the Chang’E-3 lunar lander was a crosssupport structure. The bottom of the tanks was assembled on the interface ring and the
upper part was connected with the structure through the rod. The virtual assembly
technology was applied in the tank assembly to simulate and analyze the process
of tank assembly. The assembly sequence of the tank and the 7500 N engine was
confirmed, and the risk in tank assembly process was identified. By planning and optimizing the lifting path of the tank, the implementation risk was effectively eliminated
and the four tanks were assembled symmetrically in success.
3. Assembly of Gas Tank Fixed in Clamp Band
Generally, the gas tank of common spacecraft is fixed by rods on base, while the gas
tanks of the Chang’E-3 lunar lander were fixed by the clamp band. During the process
of filling and deflation in gas tanks, the outer diameter of the tanks would be changed
with the inner pressure change. Therefore, the tanks should not be completely fixed
in assembly. In the tank assembly, the test of filling and deflation test was conducted
to verify the torque for the fixed fastener. At the same time, the film of special
material was put between the tank and the clamp band to meet the requirements of
the expansion and contraction of the tank.
4. Assembly of 7500 N Engine
Because the large engine was in the mid-bottom of the Chang’E-3 lunar lander, the
upper part was the main structure. The assembly method was not the same as the tank
assembly, which could not be assembled by ordinary lifting methods. At the same
time, there was alignment requirement for the 7500 N engine assembly. At early stage
of development, a new type of assembly process method was designed for the engine
assembly of the lunar lander. A reversed docking process method was proposed, in
which the large engine was aligned with the lunar lander by multiple lifting processes.
The 5-DOF park attitude adjustment device was designed to connect and assemble
the large engine with the lunar lander. At the same time, the alignment accuracy of
the engine was examined during assembly process to avoid deformation caused by
uneven force during the assembly process of the top and bottom fasteners on the
engine. At last, the high-precision assembly and alignment of the large engine was
achieved.
12.5.2 Instrument Assembly
The instrument assembly is the typical one in spacecraft system integration and
assembly. The assembly of the instrument was to connect the instrument with the
structure, measure the torque and prevent loosening. At the same time, according
to the performance and characteristics of the instrument, necessary process design
should be conducted to meet the different assembly requirements of different
instruments.
1. Assembly of Instrument with Alignment Requirement
12 Integration and Assembly Technology of Lunar Lander
cylinder through the lug. The structure of the Chang’E-3 lunar lander was a crosssupport structure. The bottom of the tanks was assembled on the interface ring and the
upper part was connected with the structure through the rod. The virtual assembly
technology was applied in the tank assembly to simulate and analyze the process
of tank assembly. The assembly sequence of the tank and the 7500 N engine was
confirmed, and the risk in tank assembly process was identified. By planning and optimizing the lifting path of the tank, the implementation risk was effectively eliminated
and the four tanks were assembled symmetrically in success.
3. Assembly of Gas Tank Fixed in Clamp Band
Generally, the gas tank of common spacecraft is fixed by rods on base, while the gas
tanks of the Chang’E-3 lunar lander were fixed by the clamp band. During the process
of filling and deflation in gas tanks, the outer diameter of the tanks would be changed
with the inner pressure change. Therefore, the tanks should not be completely fixed
in assembly. In the tank assembly, the test of filling and deflation test was conducted
to verify the torque for the fixed fastener. At the same time, the film of special
material was put between the tank and the clamp band to meet the requirements of
the expansion and contraction of the tank.
4. Assembly of 7500 N Engine
Because the large engine was in the mid-bottom of the Chang’E-3 lunar lander, the
upper part was the main structure. The assembly method was not the same as the tank
assembly, which could not be assembled by ordinary lifting methods. At the same
time, there was alignment requirement for the 7500 N engine assembly. At early stage
of development, a new type of assembly process method was designed for the engine
assembly of the lunar lander. A reversed docking process method was proposed, in
which the large engine was aligned with the lunar lander by multiple lifting processes.
The 5-DOF park attitude adjustment device was designed to connect and assemble
the large engine with the lunar lander. At the same time, the alignment accuracy of
the engine was examined during assembly process to avoid deformation caused by
uneven force during the assembly process of the top and bottom fasteners on the
engine. At last, the high-precision assembly and alignment of the large engine was
achieved.
12.5.2 Instrument Assembly
The instrument assembly is the typical one in spacecraft system integration and
assembly. The assembly of the instrument was to connect the instrument with the
structure, measure the torque and prevent loosening. At the same time, according
to the performance and characteristics of the instrument, necessary process design
should be conducted to meet the different assembly requirements of different
instruments.
1. Assembly of Instrument with Alignment Requirement