Hang Zhou Dawn Air Conditioning Co .,Ltd.

Reasonable manufacturing process
1 Tolerance control tube and pore
(1) when the heat exchange tubes in the procurement requirements of each heat exchanger tubes used in the drawing process should be used for the same stock (furnace batch) of raw materials, and checking on the same test approved by the trombone machine production, so as to ensure that each heat exchange with the same material, size and accuracy. Tube diameter to ensure uniform pore tube and tube plate gap, can guarantee the uniform diameter and fluid head bag expanding machine matching inflation, thereby prolonging the life of the first expansion. General tube and tube plate clearance requirements management control larvae L (O.3 ± O.05) mm range, while the fluid bag bulging head tube expander tube diameter and inner diameter tolerance should also be controlled (O.3 ± 0.05) ram range.
(2) tube plate
In order to heat exchanger tube plate and tube diameter pore within the same tolerance, the first arrival of tubes must be based on the actual diameter of tube plate pore size determines the precision of machining accuracy, as mentioned above, tube plate pores and uniform diameter tubes have been delivered the actual gap should control (O.3 ± 0.05) EITI range.
2 exchange pipe and plate processing and acceptance of
(1) Tube
① purchase required libraries into the plant before the tubes were relevant standards should be itemized inspection, precise measurement, the diameter and the tolerance range.
② Tube wear a tube shell before the actual measurement of the length of one-time cut and tubes, to avoid wearing tube feet to the grinding wheel machine. When using grinding wheel machine, the grinding wheel abrasive easy to splash people pore tube and tube plate gap, the silicate grains will be produced in the welding slag, causing risks to the welded joints.
③ Tube Expansion through the range of former District of rust should be handled outside pipe end to remove burrs, which is the first time by liquid bag inflation evaporator coils is especially important.
(2) tube plate
① tube sheet forgings should be qualified, the internal material should be uniform, Expanded Expansion had no effect on the quality of surface defects. The key for the device heat exchanger, as far as possible high-level forging, forgings, after acceptance of the relevant standards in addition, ultrasound should be done review.
② tube sheet and baffle plate pores processing must ensure concentricity. Bored with the same piece of the template to ensure that each heat exchange tube adopted by the board baffle plate and pore in the same center line, or will happen very difficult to wear tube.
③ tube sheet drilling roughness, the width of the tube sheet tube bridge according to GB151-1999 I-level requirement and acceptance.
④ pore precision from a self-pass rules and regulations only to test, and recorded. Such as requiring drilling (25.4 ± 0.05) mm, that is until the election rules 25.45mm, 25.3mm to pass rules, you can check-by-hole, hole should be made for the ultra poor marks in order to take special measures to compensate.
⑤ If the strength of expansion, expansion slot depth should ensure that (O.5 ± O.05) InlTl range. Expansion for the fluid bag approach, based on current scientific research and test results, the proposed width is 8mm, slot spacing of 8mm, usually double cell structure.
⑥ strictly before Expansion clean pores, remove the burr slot, does not allow close Expansion influential presence of impurities.
3 the connection tube and tube plate
(1) Expansion
Hydraulic fluid bag is recommended Expansion way to ensure uniform tightness Expansion. Expanding machine because of its fluid bag Expansion pressure is set by hand, computer-controlled operation and high precision, such as carbon steel tubes +25 × 2.5 paste inflation pressure is usually 1 10-120MPa, intensity of inflation pressures 170-180MPa. When the tubes with special specifications can be calculated, and then through simulation experiments confirm that inflation and the strength of its paste suitable for hydraulic expansion of the range, to ensure the reliability of the Expanded Joints.
(2) Welding
Commonly used welding with filler wire. Weld height H to ensure that no less than 1.4 times the wall thickness. Using double welding, and arc weld the second layer at least the first layer off from the arc spot weld 15. To remove the first layer of weld metal in particular, income from the arc point arc and possible defects.
(3) connection
Design drawings for the "strength of solder paste expansion +", we can use the following two ways:
① paste expansion (filled with water leak); strength welding (pressure test).
② strength welding (pressure test); paste expansion (pressure test). When the tube sheet holes overweight, should be affixed to inflation, and then welded, so as not to affect the weld quality when expanded joint. Design drawings for the "Expansion + seal weld strength", the proposed use of the following ways:
Post expansion (water containers and leak testing); seal welding (pressure test); strength of expansion (pressure test).
4 Conclusion
Because the basic materials of domestic condenser coils, precision and processing methods did not reach the optimal combination, resulting in relatively lower heat exchanger life. Expansion has been widely used and use the structure of welded heat exchanger, combined with China's national conditions, through a series of quality control measures, can produce high-quality, long life, customer satisfaction, the heat exchanger.