A hook body casting process

Abstract

The present invention provides a process for casting a hook body, which relates to the technical field of processing hook body castings. The process for casting the hook body mainly includes steps such as wax pattern preparation, wax pattern coating, mold shell preparation, melting and casting, sand cleaning, welding repair, heat treatment, etc. The present invention overcomes the deficiencies of the prior art, improves the stability of the casting process, reduces the defects on the surface of the hook body castings, ensures the mechanical properties of the castings, and extends the service life of the castings.

Description

Technical Field

[0001] The present invention relates to the technical field of processing of hook body castings, and specifically relates to a hook body casting process. Background Art

[0002] With the rapid development of society, the application of casting is becoming more and more extensive, and people's requirements for castings are also getting higher and higher. The hook body is a commonly used component in the automotive and petroleum fields, and most of its processing methods adopt casting preparation. However, due to the complex structure of the hook body, general casting is likely to cause certain shrinkage porosity defects on the surface or inside of the hook body, affecting the service life of the finished castings.

[0003] Traditional hook body casting mostly uses multiple molds for raw material casting and then demolding and installation. However, existing molds are prone to shrinkage during high-temperature casting and subsequent cooling processes, resulting in errors in the shaping of internal raw materials. At the same time, uneven heating is likely to cause defects such as pores or shrinkage holes on the surface of the castings, and subsequent heat treatment is also likely to cause surface defects of the castings, affecting the actual use effect. Summary of the Invention

[0004] Aiming at the deficiencies of the existing technology, the present invention provides a hook body casting process, which improves the stability of the casting process, reduces the defects on the surface of the hook body castings, ensures the mechanical properties of the castings, and improves the service life of the castings.

[0005] To achieve the above objectives, the technical solution of the present invention is realized through the following technical solutions:

[0006] A hook body casting process, the casting process includes the following steps:

[0007] (1) Wax pattern preparation: Inject low-temperature wax into the mold, keep it under pressure and then cool and take it out, and then perform wax trimming and mold assembly to obtain a wax pattern for standby;

[0008] (2) Wax pattern coating: Two surface layers, two transition layers, four backing layers and an external sealing slurry layer are sequentially arranged on the outside of the above wax pattern, and a layer of iron wire is tied to the outside of the first backing layer structure. Each layer structure is first coated with a compound slurry, then coated with sand, and then coated with a hardening solution, and the external sealing slurry layer is directly coated with a hardening solution after being coated with a slurry;

[0009] (3) Mold shell preparation: Place the wax pattern after drying the above coating in a water bath for heating, melt the wax pattern and then clean it, and then dry it to obtain a mold shell;

[0010] (4) Melting and casting: Place the above mold shell in a high-temperature furnace for roasting and then keep it warm, then melt the hook body steel raw material and pour out the molten steel for casting, and then cool it to room temperature, and demold to obtain a hook body casting for standby;

[0011] (5) Sand cleaning: Initially clean the surface of the cooled hook body casting, then perform flame cutting, and finally remove the remaining sand for standby;

[0012] (6) Welding repair: Preheat the casting after sand cleaning and then perform welding. After welding, cool it slowly and carefully grind the weld scars to obtain the welded repair casting for standby;

[0013] (7) Heat treatment: Place the welded repair casting in a furnace, heat it up to 900 - 920 °C for holding and normalizing treatment for 3.5 - 4.5 h, then cool it to room temperature, heat it up to 890 - 910 °C for quenching treatment for 3.5 - 4.5 h, then water-cool it to room temperature, heat it up to 570 - 590 °C for tempering for 3 - 4 h, then cool it again, and finally perform surface hanging and polishing treatment to obtain the hook body.

[0014] Preferably, for the first layer structure of the surface layer in step (2): the slurry is a slurry prepared from water glass with a viscosity of 25 - 40 s and quartz powder, the sand and gravel is quartz sand with a mesh size of 40 - 70, and the hardening liquid is ammonium chloride with a specific gravity of 1.07 - 1.1; for the second layer structure of the surface layer: the slurry is a slurry prepared from water glass with a viscosity of 20 - 30 s and quartz powder, the sand and gravel is quartz sand with a mesh size of 20 - 40, and the hardening liquid is ammonium chloride with a specific gravity of 1.07 - 1.1; for the first layer structure of the transition layer: the slurry is a slurry prepared from water glass with a viscosity of 25 - 35 s, quartz powder and refractory clay, the sand and gravel is quartz sand with a mesh size of 10 - 20, and the hardening liquid is aluminum chloride with a specific gravity of 1.17 - 1.30; for the second layer structure of the transition layer: the slurry is a slurry prepared from water glass with a viscosity of 25 - 35 s, quartz powder and refractory clay, the sand and gravel is quartz sand with a mesh size of 6 - 12, and the hardening liquid is aluminum chloride with a specific gravity of 1.17 - 1.30; for the first to fourth layer structures of the backing layer: the slurry is a slurry prepared from water glass with a viscosity of 45 - 55 s, quartz powder and refractory clay, the sand and gravel is ceramic particle sand, and the hardening liquid is aluminum chloride with a specific gravity of 1.17 - 1.30; for the external sealing slurry layer: the slurry is a slurry prepared from water glass with a viscosity of 45 - 55 s, quartz powder and refractory clay, and the hardening liquid is aluminum chloride with a specific gravity of 1.17 - 1.30.

[0015] Preferably, in step (4), the temperature for shell baking is 820 - 840 °C and the holding time is 1 - 2 h.

[0016] Preferably, the mass percentages of the raw materials of the hook body steel are: C: 0.25% - 0.28%, Si: 0.40% - 0.50%, Mn: 1.3% - 1.5%, Cr: 0.5% - 0.6%, Ni: 0.45% - 0.5%, Mo: 0.25% - 0.3%, Al: 0.03% - 0.05%, P: 0 - 0.03%, S: 0 - 0.03%, Cu: 0 - 0.03%, Ce: 0 - 0.74% and the balance is Fe.

[0017] Preferably, in step (4), the tapping temperature of the raw material of the hook body steel after melting is 1580 - 1600 °C, the casting temperature is 1530 - 1550 °C, and the temperature of the mold shell during casting is ≥ 350 °C.

[0018] Preferably, in step (7), the cooling method after normalizing treatment is air cooling, and the cooling method after tempering is air cooling.

[0019] Preferably, in step (7), the water temperature for water cooling during quenching treatment is ≤ 40 °C, and the time interval between quenching and tempering is ≤ 8 h.

[0020] The present invention provides a hook body casting process, and its advantages compared with the prior art are as follows:

[0021] (1) By applying eight layers of coatings to the outside of the wax mold, tying wire and sealing slurry, the present invention effectively improves the thermal stability of the casting mold, prevents deformation due to thermal shrinkage and expansion at the internal corners and fine parts of the mold during high-temperature casting, ensures the compactness of the casting, and at the same time, the heat and cooling are uniform, preventing damage to the surface of the casting and improving the yield.

[0022] (2) By performing normalizing, quenching and tempering treatments on the casting after welding, the present invention eliminates the internal stress of the casting, ensures the integrity of the hook body, and adopts different cooling methods to effectively improve the toughness of the casting. Specific Embodiments

[0023] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0024] Example 1:

[0025] A hook body casting process, the casting process includes the following steps:

[0026] (1) Wax mold preparation: Inject low-temperature wax at a temperature range of 48 - 52 °C under a pressure range of 0.3 - 0.5, keep the pressure for 5 - 10 s after injecting into the mold, take it out after water cooling to room temperature, and then perform wax trimming and mold assembly to obtain a wax mold for standby;

[0027] (2) Wax mold coating: Set multiple layers of structures on the outside of the above wax mold in sequence according to slurry, sand and hardening liquid, and the specific structures and drying times are shown in the following table:

[0028]

[0029]

[0030] A layer of iron wire is externally bound to the first layer of the back layer;

[0031] (3) Mould shell preparation: Place the wax mould after drying the above-mentioned coating in a water bath for heating. After melting the wax mould, clean it and then dry it to obtain the mould shell;

[0032] (4) Melting and casting: Roast the mould shell in the temperature range of 820 - 840 °C and keep it warm for 1 - 2 h. Then weigh and load the casting raw materials, add elements by power supply, deoxidize with aluminium, and adjust the composition so that the mass percentages of each component are C: 0.25% - 0.28%, Si: 0.40% - 0.50%, Mn: 1.3% - 1.5%, Cr: 0.5% - 0.6%, Ni: 0.45% - 0.5%, Mo: 0.25% - 0.3%, Al: 0.03% - 0.05%, P: 0 - 0.03%, S: 0 - 0.03%, Cu: 0 - 0.03%, Ce: 0 - 0.74% and the balance is Fe. Keep it calm for 3 - 5 minutes, remove the slag, tap the steel at 1580 - 1600 °C, and carry out casting in the temperature range of 1530 - 1550 °C, and control the temperature of the mould shell during casting ≥ 350 °C;

[0033] (5) Sand cleaning: Initially clean the surface of the hook body casting after the above cooling, then carry out flame cutting, and then carry out hanging and polishing treatment with 1.2 mm steel shot for 30 - 60 min to remove the remaining sand and reserve it;

[0034] (6) Welding repair: Preheat the casting after the above sand cleaning and then carry out welding. After welding, cool it slowly, and carefully grind the weld scar to obtain the welded repair casting for standby;

[0035] (7) Heat treatment: Place the welded repair casting in the furnace, heat it up to 900 - 920 °C for normalizing treatment for 3.5 - 4.5 h, then air cool it to room temperature, then heat it up to 890 - 910 °C for quenching treatment for 3.5 - 4.5 h, then water cool it to room temperature in an environment where the water temperature ≤ 40 °C. Within 8 h after quenching, heat it up to 570 - 590 °C for tempering for 3 - 4 h, then air cool it, and then carry out surface hanging and polishing treatment to obtain the hook body.

[0036] Example 2:

[0037] Carry out performance detection on the hooks produced in the same batch as above, and the results are shown in the following table:

[0038]

[0039]

[0040] To sum up, the finished product rate of the hook prepared in this application is high and the mechanical properties are excellent.

[0041] It should be noted that in this text, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising an..." does not exclude the existence of additional identical elements in the process, method, article or device comprising the said element.

[0042] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A hook body casting process, characterized in that, The casting process includes the following steps: (1) Wax pattern preparation: Inject low-temperature wax into the mold, keep it under pressure and then cool and take it out. Then repair the wax and assemble the mold to obtain a wax pattern for standby; (2) Wax pattern coating: Two surface layers, two transition layers, four backing layers and an external sealing slurry layer are sequentially arranged on the outside of the above wax pattern. And a layer of iron wire is tied outside the structure of the first backing layer. Each layer structure is first coated with a compounded slurry, then coated with sandstone, and then coated with a hardening solution. And the external sealing slurry layer is directly coated with a hardening solution after being coated with a slurry; The structure of the first layer of the surface layer: The slurry is a slurry prepared from water glass with a viscosity of 25-40 s and quartz powder. The sandstone is quartz sand with a mesh size of 40-70. The hardening solution is ammonium chloride with a specific gravity of 1.07-1.1; The structure of the second layer of the surface layer: The slurry is a slurry prepared from water glass with a viscosity of 20-30 s and quartz powder. The sandstone is quartz sand with a mesh size of 20-40. The hardening solution is ammonium chloride with a specific gravity of 1.07-1.1; The structure of the first layer of the transition layer: The slurry is a slurry prepared from water glass, quartz powder and refractory clay with a viscosity of 25-35 s. The sandstone is quartz sand with a mesh size of 10-20. The hardening solution is aluminum chloride with a specific gravity of 1.17-1.30; The structure of the second layer of the transition layer: The slurry is a slurry prepared from water glass, quartz powder and refractory clay with a viscosity of 25-35 s. The sandstone is quartz sand with a mesh size of 6-12. The hardening solution is aluminum chloride with a specific gravity of 1.17-1.30; The structures of the first to fourth layers of the backing layer: The slurry is a slurry prepared from water glass, quartz powder and refractory clay with a viscosity of 45-55 s. The sandstone is ceramic particle sand. The hardening solution is aluminum chloride with a specific gravity of 1.17-1.30; The external sealing slurry layer: The slurry is a slurry prepared from water glass, quartz powder and refractory clay with a viscosity of 45-55 s. The hardening solution is aluminum chloride with a specific gravity of 1.17-1.30; (3) Mold shell preparation: Place the wax pattern after drying the above coating in a water bath and heat it. Melt the wax pattern, clean it, and then dry it to obtain a mold shell; (4) Melting and casting: Place the above mold shell in a high-temperature furnace for roasting and then heat preservation. Then melt the raw material of the hook body steel, tap the steel and cast it, and then cool it to room temperature and demold to obtain a hook body casting for standby; (5) Sand cleaning: Roughly clean the surface of the above cooled hook body casting, then perform flame cutting, and then remove the remaining sand for standby; (6) Welding repair: Preheat the casting after the above sand cleaning and then perform welding. After welding, cool it slowly and carefully polish the weld scar to obtain a welded repair casting for standby; (7) Heat treatment: Place the above welded repair casting in a furnace, heat it up to 900-920 °C for holding and normalizing treatment for 3.5-4.5 h, then cool it to room temperature, then heat it up to 890-910 °C for quenching treatment for 3.5-4.5 h, then water-cool it to room temperature, then heat it up to 570-590 °C for tempering for 3-4 h, then cool it, and then perform surface hanging and polishing treatment to obtain a hook body.

2. The hook body casting process according to claim 1, characterized in that: In the step (4), the roasting temperature of the mold shell is 820-840 °C, and the heat preservation time is 1-2 h.

3. A hook body casting process according to claim 1, characterized in that: The mass percentages of the raw materials of the hook body steel are as follows: C: 0.25% - 0.28%, Si: 0.40% - 0.50%, Mn: 1.3% - 1.5%, Cr: 0.5% - 0.6%, Ni: 0.45% - 0.5%, Mo: 0.25% - 0.3%, Al: 0.03% - 0.05%, P: 0 - 0.03%, S: 0 - 0.03%, Cu: 0 - 0.03%, Ce: 0 - 0.74%, and the balance is Fe.

4. A hook body casting process according to claim 1, characterized in that: In the step (4), the tapping temperature after melting the raw materials of the hook body steel is 1580 - 1600 °C, the casting temperature is 1530 - 1550 °C, and the temperature of the mold shell during casting is ≥ 350 °C.

5. A hook body casting process according to claim 1, characterized in that: In the step (7), the cooling method after normalizing treatment is air cooling, and the cooling method after tempering is air cooling.

6. A hook body casting process according to claim 1, characterized in that: In the step (7), the water temperature for water cooling during quenching treatment is ≤ 40 °C, and the time interval between quenching and tempering is ≤ 8 h.

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