Views:5416 Author:Site Editor Publish Time: 2020-06-02 Origin:Site
Metal bellows is mainly used to compensate axial displacement, and can also compensate lateral displacement or combined axial and lateral displacement. It has the ability to compensate angular displacement, but metal bellows are generally not used to compensate angular displacement.
1. Metal bellows are classified by material
Bellows H80 H -60℃～+100℃ Low elasticity, large hysteresis and aftereffect, good brazing performance. It can be used as a measuring element in non-corrosive media and instruments with low accuracy.
2. Tin bronze
Bellows QSn6.5～0.1 X -60℃～+100℃ Elasticity, strength and corrosion resistance are good, hysteresis and elastic aftereffect are small, brazing is good, and it is widely used as a measuring element.
3. Beryllium bronze
Bellows QBe2 P -60℃～+150℃ has little hysteresis and elastic aftereffect, high elastic stability, corrosion resistance and non-magnetic. Mostly used in high-precision measuring instruments.
4. Stainless steel
Bellows 1Cr18Ni9Ti G -194℃～+400℃ Has high bending fatigue strength and corrosion resistance, good welding performance. Can be used as a measuring, sealing, connecting and compensating element in corrosive media.
Second, the manufacturing process of metal bellows
1. Heat treatment of bellows
Heat treatment is an indispensable and important process in the manufacturing process of bellows and in obtaining elastic properties of bellows.
The bellows material can be divided into work hardening type and dispersion strengthening type according to the strengthening method. Commonly used hardening materials include H80, QSn6.5-0.1, NiCu28-2.5-1.5, 1Cr18Ni9Ti and 00Cr17Ni14Mo2. After recrystallization annealing or quenching solution treatment, they form a single α solid solution or a single austenite, have excellent plastic deformation properties, can meet the requirements of diameter reduction, thinning and forming process, cold deformation during bellows forming During the process, the material is work hardened, GH4132, GH4169, etc. In the quenched solid solution state, they form a single supersaturated solid solution, which has excellent plasticity and can meet the plastic deformation performance of cold working. During the aging heat treatment after bellows forming, the dispersed strengthening phase precipitates to strengthen the material, thereby making the bellow Obtain excellent elasticity performance.
The purpose of the heat treatment of the bellows is twofold: one is to eliminate work hardening and restore plasticity during the manufacturing process of the bellows; the other is to strengthen the material and obtain elasticity.
The heat treatment of bellows has internal and external quality requirements. Intrinsic quality is to obtain a certain structure state, grain size and mechanical properties of the material after heat treatment; external quality is mainly the degree of surface oxidation after heat treatment.
2. Surface treatment of bellows
a. Surface treatment process of copper alloy
The surface treatment process of the copper alloy bellows includes degreasing, loose oxide scale, weak pickling, bright pickling and passivation.
b. Surface treatment process of stainless steel
The surface treatment process of stainless steel bellows is mainly for degreasing, loosening oxide scale and pickling.
3. The shaping process of bellows
After the bellows is formed, due to the elastic rebound, the wave pitch and wave shape of the bellows are different from the requirements of the suction meter, and they must be reshaped.
For bellows made of work hardened materials, manual and mechanical shaping methods are generally used. For the corrugated pipe of dispersion hardened material, put it into the aging fixture and age to shape the bellows to achieve the shaping effect.
4. Stabilization process of bellows
During the processing of the bellows, internal stress will be generated, making it springy and unstable in geometry. The purpose of stabilizing the bellows is to eliminate stress, stabilize performance, and stabilize geometric dimensions.
The stabilization treatment of bellows includes thermal stabilization treatment process and mechanical stabilization treatment process. Under normal circumstances, only heat stabilization treatment, mechanical stabilization treatment only when there are special requirements.