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.
Example . Sleeve
1.Material: 45 steel. 2.Hole and external round chamfer C1. 3.Quenching 45~50HRC.
1.Part drawing analysis
1) The axis of the outer circle of ϕ45 + 0.089 is used as the reference, and the coaxiality tolerance between the axis of the ϕ30H6 hole and the reference is ϕ0. 005mm.
2) The axial circular runout tolerance between the left end face and the datum is 0.005mm.
3) The material of the parts is 45 steel.
4) The quenching hardness is 45 ~ 50HRC.
1) The length of this piece is short, it can be processed with long material, and then cut off.
2) The part is in the roughing stage before heat treatment, and the end face, outer circle and hole can be directly processed in one clamping. After the heat treatment is the finishing stage, the outer circle is positioned to grind the hole, and then the outer circle is positioned to grind the outer circle to ensure the coaxiality requirement.
sleeves Machining process
|Part Name||Blank species||Material||Production type|
|Sleeve||Round steel||45 # steel||Small batch|
|Process||Work step||Process content||Equipment||Tools, measuring tools, auxiliary tools|
|10||Cutting ϕ 50 × 300||Sawing machine|
|20||Rough turning||Horizontal lathe|
|1||Clamp the outer circle of the blank, with a protruding length of 30 to 50, turning the end face until it is flat||45° elbow turning tool|
|2||Drilling ϕ 20||ϕ20 Twist drill|
|3||Boring to ϕ 29. 70||Boring tool|
|4||Turn the outer circle to ϕ45. 30||45° elbow turning tool|
|5||Internal and external round chamfering, turning to C1.3||45° elbow turning tool|
|6||Cut off, guarantee length 22.6||Cutting knife|
|7||Turn around. Clamp the outer circle and turn the end face to ensure the length 22. 1||45° elbow turning tool|
|8||Internal and external round chamfering, turning to C1.3||45° elbow turning tool|
|30||Heat treatment: quenching, 45 ~ 50HRC||Salt bath furnace|
|40||Grind the inner circle and end face||CNC Internal Grinding Machine|
|1||Clamp the outer circle, grind the ϕ30H6 hole to the requirement, surface roughness Ra0.8μm|
|2||Grind the left end face to the requirement, surface roughness Ra0. 8μm|
|50||Grinding the outer circle: Use the inner hole to locate, penetrate the taper mandrel, and grind the outer circle to the requirement of ϕ45 +0.0859, surface roughness Ra0. 8μm||CNC cylindrical grinder|
|70||Oiling, packaging, warehousing||Warehouse|