Spacecraft Manufacturing Technology
As an important part of the spacecraft thermal control protection system, the thermal control coating is like the skin of the human body, protecting the spacecraft from operating in various complex space environments.It is of great significance to ensure the normal operation of various parts and structures inside the spacecraft.
The performance of the thermal control coating mainly depends on the surface characteristics of the coating. The most important parameters are the solar absorption ratio αs and the hemispheric emission rate £H.Each material has a specific solar absorption ratio and hemispherical emissivity, and theoretically can be applied to a certain thermal environment to achieve a certain thermal control function.But the actual situation is: a single material often cannot meet the design requirements of spacecraft in terms of heat radiation performance, mechanical properties, specific gravity, and cost.For example, aluminum alloy is the most commonly used material in spacecraft. It has the advantages of low specific gravity, high strength, and relatively low cost. However, in some parts of stars and ships, the heat radiation performance of aluminum alloy cannot meet the demand.From the comprehensive consideration of thermal performance, mechanical performance, cost and other aspects, the best solution is to cover the surface with a layer of material with the required thermal radiation performance, that is, a thermal control coating, so as to achieve a balanced combination of multiple properties.
1.Material: 45 steel. 2.All chamfering C1. 3.Fire 45~52HRC on the left end face.
1.Part drawing analysis
1) This part is a thin-walled cylinder liner, which is characterized by very thin hole walls.
2) The part takes the ϕ90G6 hole as the reference A, and the coaxiality tolerance of the outer circle of ϕ100js5 to the reference A is ϕ0.01mm.
3) The parallelism tolerance of the right end facing datum B is 0.02mm.
4) The roundness tolerance of the ϕ90G6 hole and ϕ100js5 outer surface is 0.005mm.
5) Heat treatment: normalizing 190～207HBW, left end quenching: 45～52HRC.
6) Part material: 45 steel.
1) This part is a thin-walled part. Due to the poor rigidity, the cutting force and clamping force are prone to deformation during the turning process, which affects the dimensional accuracy and shape accuracy of the workpiece. Therefore, a reasonable choice of clamping method, tool geometric angle, cutting amount and adequate cooling and lubrication are the keys to ensuring machining accuracy.
2) The outer circle and inner hole of this part have high precision requirements, so they should be divided into rough and fine separation during processing.
Sleeves Mechanical processing process (unit: mm)
|Part Name||Blank species||Material||Production type|
|Sleeve||Round bar||45 # steel||Small batch|
|Process||Work step||Process content||Equipment||Tools, measuring tools, auxiliary tools|
|10||Blanking ϕ 120 × 26||Sawing machine|
|1||Use a self-centering chuck to clamp one end of the outer circle of the blank, align, clamp, and turn the end face into a flat surface.||45° elbow turning tool|
|2||Drill ϕ90G6 hole to ϕ50||ϕ50 twist drill|
|3||Boring the ϕ90G6 hole, leaving a grinding allowance of 0.50||Boring tool|
|4||Turning ϕ100js5 External grinding allowance 0.50||90° external turning tool|
|5||Turning size 14, left grinding allowance 0. 10||90° external turning tool|
|6||Turning hole and external round chamfer C1||45° elbow turning tool|
|7||U-turn, clamp the outer circle of ϕ100js5, turn the end face, leave a grinding allowance of 0.10, and ensure the total length is 18. 20||45° elbow turning tool|
|8||Turning ϕ110 outer circle to the required surface roughness Ra3. 2μm||90° external turning tool|
|9||Turning hole and external round chamfer C1||45° elbow turning tool|
|40||Heat treatment: quenching 45 ～ 52HRC||High frequency induction hardening|
|50||Inner hole grinder lathe|
|Inner hole grinding|
|1||Align the left end surface and inner hole, and grind the ϕ90G6 hole to the requirement， surface roughness Ra0. 8μm|
|2||Grind the left end face to the requirement, surface roughness Ra0. 8μm, guaranteed size 18|
|60||Cylindrical grinding||Cylindrical grinder|
|1||The work piece is sleeved on the taper mandrel, ground ϕ100js5 outer circle to the required surface roughness Ra0. 8μm||Taper mandrel ϕ90|
|2||Grinding size 14 left to the requirements, surface roughness Ra0. 8μm|
|1||Inspection of ϕ100js5 outer circle, ϕ90G6 inner hole size, roundness, cylindricity, coaxiality||Three coordinate measuring instrument, micrometer, etc.|
|2||Check surface roughness||Roughness Tester|
|80||Oiling, packaging, warehousing||Warehouse|