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The whole production process of plugging of marine heat exchanger

This product is the plugging of marine heat exchanger. It is made of CF8M, weighs 57.2kg and has an overall wall thickness of 8mm. The original process is formed by stamping steel plate and then welded with plate and pipe. It has low production efficiency, complex manufacturing process and high cost. In addition, it requires high flaw detection cost, and the appearance needs surface treatment to achieve good roughness, The dimensional accuracy can not meet the requirements of use. The integrated molding of precision casting saves expensive welding costs, meets the requirements of dimensional accuracy, and the surface roughness reaches more than Ra6.3, which can meet the use requirements of customers.

20210825020031 90693 - The whole production process of plugging of marine heat exchanger

The picture is a 3D picture of the product

Trial production process

Mold making

The die is integrally formed and made of forged aluminum 6061. The die size is about: length × wide × Height = 650mm × 650mm × 420mm, the upper core adopts pneumatic coring, and the mold shape is shown in the figure below:
20210825020248 14785 - The whole production process of plugging of marine heat exchanger

Module

A 20T single station wax jetting machine is used for wax jetting. The wax jetting temperature is 52 ℃, the wax jetting pressure is 3.5Mpa, the wax jetting time is 20 minutes and the pressure is maintained for 3 minutes. The electric hoist provided by the wax jetting machine is used for auxiliary mold opening, and the wax mold is water-cooled. The sponge is used to stand on tiptoe at the bottom in the wax turnover process, modification and group number. When assembling the tree, it is supported by the tree support, It is bonded with adhesive wax. The upper part of the die head is reinforced with four auxiliary lifting platforms to increase the lifting strength of the whole module. The tree assembly process diagram and process simulation are shown in the following figure:

20210825020428 38030 - The whole production process of plugging of marine heat exchanger

Shell making

The mold shell consists of 8 layers, including zircon sand on the surface layer, mullite sand on the transition layer of 50-100 mesh, mullite sand on the back layer of 30-60 mesh (one layer) and mullite sand on the back layer of 16-30 mesh (repeat five layers), and the drying time of each layer is 24 hours. Steel wire mesh is used to reinforce the mold shell after 5 layers of shell making. The traditional shell making operation is manual direct slurry bonding, rain or boiling sand spreading, but due to the large product, It is difficult to operate manually directly. To solve this problem, our company has developed a movable shell making auxiliary trolley for slurry coating. It can adjust the height and rotate 360 degrees in both directions, which greatly reduces the labor intensity of workers. In addition, for the blind cabin inside the shell, the process of filling dry sand after 4 layers is adopted, In order to avoid poor drying of the inner cavity and solve the difficulty of shell cleaning in the cleaning process. The drying method is hanging drying in the directional drying chamber to facilitate the drying of the inner cavity of the shell, as shown in the figure below:

20210825020547 28098 - The whole production process of plugging of marine heat exchanger

Electric steam dewaxing kettle is used for dewaxing, one for each furnace, and the dewaxing time is 15 minutes.

Shell roasting

Gas fired baking furnace is used for shell baking. The baking temperature is 1120 ℃ and the baking time is 1.5 hours. Due to the heavy shell, it is difficult to use the traditional fork shell furnace and pouring. During the trial production, we designed the shell baking tooling (welded by 50 * 50mm steel plate), The furnace shall be installed together with the shell to facilitate the taking and placing of the shell. The shell shall be installed and taken out by manual forklift (the teeth of the forklift shall be wrapped with fire-resistant cotton in advance to avoid high-temperature heating deformation), as shown in the following figure:
20210825020636 45334 - The whole production process of plugging of marine heat exchanger

Pouring

Subcontracting pouring is adopted in the pouring process. Since the overall wall thickness of the product is only 8mm, in order to ensure that the metal is fully filled with the mold, the pouring temperature is 1680 ℃ for rapid pouring. There is no problem of insufficient pouring after pouring. The castings after pouring are shown in the figure below:
20210825020720 87659 - The whole production process of plugging of marine heat exchanger

Clear

The post-treatment process is the normal process flow – Manual shell vibration → shot blasting → cutting → grinding → shot blasting → welding repair → heat treatment → shot blasting → acid pickling → shot blasting → passivation → machining → pressure test → detection → warehousing → packaging. Due to the heavy casting, the grinding process is assisted by self-made electric gourd grinding, and the turnover of products in the cleaning workshop is carried out by turnover vehicles:
20210825020809 73223 - The whole production process of plugging of marine heat exchanger

Summary

The silica sol process precision casting can produce castings with a weight greater than 50kg, the dimensional accuracy can meet the CT6 requirements of GB/T6414-1999, and the surface roughness can reach ra6.3. Special auxiliary tools are used in the shell making process, auxiliary tooling is used for shell baking, and hoisting tools are used in the cleaning process, The labor intensity of workers is reduced. The overall casting of welded products reduces the production cost. The trial production of castings has been completed and can initially meet the requirements of mass production

Source: Network Arrangement – China Flanges Supplier: www.epowermetals.com

(Yaang Pipe Industry is a leading manufacturer and supplier of nickel alloy and stainless steel products, including Super Duplex Stainless Steel Flanges, Stainless Steel Flanges, Stainless Steel Pipe Fittings, Stainless Steel Pipe. Yaang products are widely used in Shipbuilding, Nuclear power, Marine engineering, Petroleum, Chemical, Mining, Sewage treatment, Natural gas and Pressure vessels and other industries.)

If you want to have more information about the article or you want to share your opinion with us, contact us at sales@epowermetals.com

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