valve sleeve hole to ensure the requirement of fit clearance. There are many grooves
on the surface of the hole. Previously, it was difficult to measure the minimum
aperture and the wear of the measuring head by using the small-hole gauge. It was
easy to produce the error that the measured value was larger than the actual value,
resulting in the composite clearance between the valve sleeve and the valve core
less than the required value, which caused the valve core to stop swinging when the
gas steering engine was ignited. Later, the measurement method was improved by
using the small-hole scale combined with the grouping plug rod. At the same time,
changing the original method of measuring and matching only by assembly
workers, first by specialized personnel to measure and match, then by assembly
workers to self-test, inspectors to reexamine, find problems and coordinate treatment in time, improve the reliability of measurement, ensure the fit clearance.
The metallographic structure of each valve plate that makes up the valve sleeve
has an important influence on the mating clearance between the valve sleeve and the
spool. A batch of products had been faulted during ignition because of excessive
retained Austenite in the metallographic structure of valve plates. Later, monitoring
was strengthened during heat treatment of valve plates. After heat treatment, the
inspection requirement of metallographic structure was increased to ensure the
stability of the hole size and clearance of valve sleeve under gas working condition.
10.4.4 Shell Assembly Quality
The shell assembly consists of a combination valve sleeve and a shell. Shell
assembly is the key component of gas steering engine, which has a key characteristic and an important characteristic. The quality of shell assembly has an
important influence on the reliability and performance of gas steering engine. Due
to the high precision requirement, many processing and assembly procedures, and
complex influencing factors of shell components, the qualified rate of shell components in a long period of time is only about 60%. After tackling key technical
problems, these problems have been solved.
(1) Major Quality Problems
The coaxiality of 2 Â /3:5 mm hole to /2:5 mm hole exceeds the design
requirement. The qualified rate is 60 $ 70%. /2:5 mm hole cylinder exceeds the
design requirements. After vacuum quenching treatment, the /3:5 mm orifices of
left and right external valve plates shrink to form an inverted cone. The uneven
distribution of oxide skin on the surface of the hole affects the flexible and reliable
movement of the bushing.
(2) Improvement Measures
Improve the accuracy and quality of the valve plate. Improve the verticality of
/2:5 mm hole on the valve plate to the end surface, and ensure the coaxiality
10.4 Process Technology of Gas Steering Engine
191
on the surface of the hole. Previously, it was difficult to measure the minimum
aperture and the wear of the measuring head by using the small-hole gauge. It was
easy to produce the error that the measured value was larger than the actual value,
resulting in the composite clearance between the valve sleeve and the valve core
less than the required value, which caused the valve core to stop swinging when the
gas steering engine was ignited. Later, the measurement method was improved by
using the small-hole scale combined with the grouping plug rod. At the same time,
changing the original method of measuring and matching only by assembly
workers, first by specialized personnel to measure and match, then by assembly
workers to self-test, inspectors to reexamine, find problems and coordinate treatment in time, improve the reliability of measurement, ensure the fit clearance.
The metallographic structure of each valve plate that makes up the valve sleeve
has an important influence on the mating clearance between the valve sleeve and the
spool. A batch of products had been faulted during ignition because of excessive
retained Austenite in the metallographic structure of valve plates. Later, monitoring
was strengthened during heat treatment of valve plates. After heat treatment, the
inspection requirement of metallographic structure was increased to ensure the
stability of the hole size and clearance of valve sleeve under gas working condition.
10.4.4 Shell Assembly Quality
The shell assembly consists of a combination valve sleeve and a shell. Shell
assembly is the key component of gas steering engine, which has a key characteristic and an important characteristic. The quality of shell assembly has an
important influence on the reliability and performance of gas steering engine. Due
to the high precision requirement, many processing and assembly procedures, and
complex influencing factors of shell components, the qualified rate of shell components in a long period of time is only about 60%. After tackling key technical
problems, these problems have been solved.
(1) Major Quality Problems
The coaxiality of 2 Â /3:5 mm hole to /2:5 mm hole exceeds the design
requirement. The qualified rate is 60 $ 70%. /2:5 mm hole cylinder exceeds the
design requirements. After vacuum quenching treatment, the /3:5 mm orifices of
left and right external valve plates shrink to form an inverted cone. The uneven
distribution of oxide skin on the surface of the hole affects the flexible and reliable
movement of the bushing.
(2) Improvement Measures
Improve the accuracy and quality of the valve plate. Improve the verticality of
/2:5 mm hole on the valve plate to the end surface, and ensure the coaxiality
10.4 Process Technology of Gas Steering Engine
191