Riser and casting system suitable for rotary castings

Abstract

The utility model discloses a kind of riser and casting system suitable for rotary casting, base sand core is located in the inside of casting cavity, sand riser is shaped on base sand core and is communicated with casting cavity by riser neck, partition sand core is embedded in the inside of sand riser, the partition sand core bottom is matched with base sand core, heat preservation riser sleeve is set on the outside of sand riser;Casting system includes the riser and a ring pouring mechanism, ring pouring mechanism includes sprue, annular cross gate and multiple ingates, annular cross gate is symmetrically connected to the bottom of sprue and is set around casting, multiple ingates are evenly distributed along the inside of annular cross gate Circumferential, constitute the structure of molten iron injection from the bottom of casting.By the above-mentioned mode, the utility model can realize efficient feeding and riser fast and neat separation, realize smooth synchronous filling, avoid shrinkage and other casting defects, strengthen casting low-temperature toughness, wear resistance and corrosion resistance, suitable for complex medium and large casting.

Description

Technical Field

[0001] This utility model relates to the field of metal casting technology, and in particular to a riser and casting system suitable for rotary castings. Background Technology

[0002] In traditional casting production, risers are crucial. The core function of risers is to compensate for the solidification shrinkage of castings and prevent the formation of shrinkage cavities and porosity inside. Currently, conventional solutions include top risers, side (edge) risers, and internal risers, depending on the casting's structure, shape, and size. Alternatively, insulating riser sleeves, high-heat riser sleeves, and composite insulating and heat-generating riser sleeves can be used to improve feeding efficiency.

[0003] However, existing solutions generally suffer from delays: obstructed feeding channels often lead to shrinkage porosity and blowholes in the castings, resulting in casting scrap; or improper gating system design causes sand erosion in the mold cavity, leading to defects such as sand holes and chipping; in the smelting process, improper control of alloy composition results in poor graphite morphology and instability in the microstructure, causing unqualified casting performance. Furthermore, unreasonable settings in existing gating schemes lead to problems such as difficulty in separating post-processing risers and gates, and easy damage from contaminated material.

[0004] The lower housing of the gearbox transmission system in offshore wind turbines is the core load-bearing structure of the transmission system. Its operating conditions are extremely complex, requiring it to withstand enormous gear meshing loads, overturning moments caused by gravity and wind loads, and alternating fatigue stresses induced by long-term sea-time fluctuations. This places far more stringent requirements on the internal quality, mechanical properties, and fatigue life of the castings than on conventional industrial castings. However, existing casting methods have the following drawbacks: First, the feeding efficiency is low and the cost is high: For rotating structures such as thick flanges, lower housings, and planetary carriers, internal risers are commonly used for feeding, employing solid sand core risers or additional insulating riser sleeves. On the one hand, a single sand riser has low feeding efficiency for the same volume, making the casting prone to shrinkage porosity, while using high-heat insulating risers is too costly; on the other hand, excessively large risers designed to ensure feeding effect result in low casting yield and low product separation efficiency in the post-processing stage.

[0005] Traditional single-sided injection gating systems are prone to localized overheating within the mold cavity, which not only exacerbates the shrinkage tendency of the casting but also leads to excessive scouring and thermal erosion of the molding sand by molten iron, causing the sand mold to collapse and resulting in sand holes and sand inclusions on the surface of the casting.

[0006] Second, the material properties cannot meet the requirements of special working conditions: Conventional compositions affect the shrinkage porosity of castings, and excessively high temperatures can easily cause shrinkage porosity in castings. Furthermore, the composition system of conventional grades such as QT400-18 (e.g., C: 3.4~3.9%; Si: 2.2~2.9%) mainly focuses on conventional room temperature performance. Its graphite morphology and matrix structure have poor stability in low-temperature environments, which cannot guarantee the performance requirements of castings under special working conditions such as -20℃, -40℃, and even -60℃, and also results in a short service life.

[0007] Third, the post-processing separation efficiency is low and the damage rate is high: After the casting is unpacked, the separation of the traditional integral large riser relies entirely on manual processing. Because the riser is relatively thick, manual separation is very difficult. The grinding process is not only extremely time-consuming and difficult to operate, but it is also easy to cause unnecessary bumps and damage to the casting during this process. This greatly affects the efficiency of post-processing and significantly increases the scrap rate of the product.

[0008] Clearly, existing casting methods are no longer able to meet the manufacturing requirements of the aforementioned high-end marine equipment in terms of feeding effectiveness, performance stability, and post-processing efficiency. Utility Model Content

[0009] The main technical problem solved by this utility model is to provide a riser and casting system suitable for rotary castings. By combining a built-in partitioned sand core riser with a through-hole insulation sleeve, efficient feeding and rapid and neat separation of the riser can be achieved, improving post-processing efficiency by more than 90%. Combined with an outer ring bottom-pouring gating system, molten iron can be stably and synchronously filled into the mold, effectively avoiding casting defects such as shrinkage porosity. Through precise control and optimization of the casting composition, the low-temperature toughness, wear resistance and corrosion resistance of the casting can be enhanced. It is suitable for a variety of complex medium and large castings and has a wide range of application prospects.

[0010] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: providing a riser suitable for rotary castings, including a base sand core, a sand riser, a partition sand core, and an insulating riser sleeve. The base sand core is disposed inside the cavity of the casting. The sand riser is formed on the base sand core and communicates with the cavity of the casting through the riser neck. The partition sand core is embedded inside the sand riser. The bottom of the partition sand core is positioned and matched with the base sand core, and divides the inner cavity of the sand riser into at least two independent feeding chambers. The insulating riser sleeve is fitted on the outside of the sand riser.

[0011] In a preferred embodiment of this utility model, the partition sand core has a trapezoidal structure, and the bottom of the partition sand core achieves concave-convex positioning cooperation through the positioning protrusion provided thereon and the positioning groove provided on the base sand core.

[0012] In a preferred embodiment of this utility model, the sand riser is an elliptical trapezoidal truncated structure.

[0013] In a preferred embodiment of this utility model, the insulating riser sleeve is a through-hole elliptical cylindrical structure adapted to the outer contour of the sand riser.

[0014] In a preferred embodiment of the present invention, the sand riser includes a riser neck communicating with each feeding chamber, and the riser neck is funnel-shaped.

[0015] In a preferred embodiment of this utility model, side chills are laid diagonally on both sides of the riser neck, and a ring of bottom chills is also laid on the bottom end face of the casting. The side chills and bottom chills together guide the casting to solidify.

[0016] To solve the above-mentioned technical problems, another technical solution adopted by this utility model is: to provide a casting system, including the riser suitable for rotary castings and an annular pouring mechanism. The annular pouring mechanism includes a sprue, an annular runner and multiple ingates. The annular runner is symmetrically connected to the bottom of the sprue and arranged around the casting. The multiple ingates are evenly distributed along the inner circumference of the annular runner, forming a structure for injecting molten iron from the bottom of the casting.

[0017] In a preferred embodiment of the present invention, the ingate has a wide and thin annular cross-section, and the number is at least eight, which are symmetrically and evenly distributed along the annular horizontal runners on both sides.

[0018] In a preferred embodiment of the present invention, a filtration and slag collection unit is arranged on each of the annular horizontal pouring channels, and the filtration and slag collection unit includes a filter block and a slag collection bag.

[0019] In a preferred embodiment of this utility model, the casting material is QT400-18L.

[0020] The beneficial effects of this utility model are: Highly efficient feeding: The built-in partitioned sand core riser, combined with the through-hole insulation sleeve, forms an efficient thermal junction and feeding channel, ensuring good feeding effect; Easy separation: By using a pre-cut section of the partition sand core, the riser and casting can be separated quickly and neatly, improving post-processing efficiency to over 90%, avoiding defects such as dents and inclusions caused by traditional grinding, and reducing costs; Stable filling: The outer ring bottom pouring system enables stable and synchronous filling of molten iron, effectively avoiding casting defects such as shrinkage porosity, sand holes, cold shuts, and gas holes. Excellent performance: Precise control of QT400-18L composition and optimization of inoculation process, while maintaining high spheroidization rate and excellent graphite morphology, enhances low-temperature impact toughness, wear resistance and corrosion resistance; High versatility: It is suitable for the production of various medium and large-sized castings with complex structures and high quality requirements, and has broad application prospects. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort, wherein: Figure 1 This is a schematic diagram of a preferred embodiment of the riser and casting system of this utility model suitable for rotary castings; Figure 2 This is a bottom view of a preferred embodiment of the riser and casting system of this utility model suitable for rotary castings; Figure 3 This is a cross-sectional view of a preferred embodiment of the riser and casting system of this utility model suitable for rotary castings; Figure 4 This is a schematic diagram of a preferred embodiment of the present invention, which is suitable for the combination of base sand core and partition sand core. Figure 5 This is a schematic diagram of a preferred embodiment of the present invention suitable for the matching of the position of the sand core and the sand riser; The components in the attached diagram are labeled as follows: 1. Insulating riser sleeve; 2. Riser neck; 3. Base sand core; 31. Positioning groove; 4. Partition sand core; 41. Positioning protrusion; 5. Side chill; 6. Casting; 7. Cavity; 8. Outer contour forming sand core; 9. Sand riser; 10. Filter block; 11. Slag collection bag; 12. Bottom chill; 13. Straight sprue; 14. Annular horizontal sprue; 15. Ingate. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. The components of the embodiments of this utility model described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0023] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0024] This invention provides a riser suitable for rotary castings.

[0025] Please see Figures 1 to 5 In this embodiment, the riser suitable for rotary castings includes a base sand core 3, a sand riser 9, a partition sand core 4, and an insulating riser sleeve 1.

[0026] In detail, the outer shape of casting 6 is formed by the outer contour molding sand core 8, and the base sand core 3 is set inside the cavity 7 of casting 6, serving as the mounting base for the riser. The sand riser 9 is formed on the base sand core 3. The sand riser 9 has an elliptical trapezoidal structure. This shape maintains a moderate distance from the inner diameter of the rotary casting, fits well with the inner cavity of the casting, and has the characteristics of good heat preservation and easy separation and removal later. The sand riser 9 communicates with the casting cavity through the riser neck 2 at its bottom. The riser neck 2 is funnel-shaped, which can provide the smoothest channel for molten iron feeding within a limited space.

[0027] Most importantly, a partition sand core 4 is pre-embedded in the middle of the sand riser 9. This partition sand core 4 has a trapezoidal structure with a positioning protrusion 41 at its bottom, which engages with the corresponding positioning groove 31 on the base sand core 3 to ensure the accuracy and stability of the core assembly. The partition sand core 4 divides the inner cavity of the sand riser 3 into at least two independent feeding chambers. After the molten iron is poured, the partition sand core disintegrates, causing the riser to naturally break into two parts during cleaning, greatly facilitating removal and cleaning.

[0028] To ensure casting stability, an insulating riser sleeve 1 is fitted on the outside of the sand riser 9. The insulating riser sleeve 1 is a through-hole elliptical cylindrical structure that matches the outer contour of the sand riser 9, like putting an insulating coat on the sand riser 9. This can significantly reduce heat loss, prolong the liquid feeding time, and enhance the heat preservation effect.

[0029] To further optimize the solidification sequence during the casting process, side chills 5 are laid diagonally on both sides of the riser neck 2 to reduce the local hot spots on both sides of the chills and reduce the tendency of shrinkage porosity in this area; similarly, a ring of bottom chills 12 is also laid on the bottom end face of the casting 6 to cool it down, block the heat at the ingate, and facilitate the simultaneous solidification of the cavity.

[0030] The aforementioned side chills 5 and bottom chills 12 together constitute a chilling system, which guides the casting 6 to solidify from the bottom and the area away from the riser neck 2, pushes the solidification front towards the riser, ensures the unobstructed feeding channel, and thus perfectly realizes the solidification principle and effectively eliminates shrinkage defects.

[0031] Please see Figure 1 This utility model also provides a casting system, including a riser suitable for rotary castings and an annular pouring mechanism.

[0032] The annular pouring mechanism includes a straight pouring channel 13, the bottom of which is symmetrically connected to two annular horizontal pouring channels 14. On the inner side of each annular horizontal pouring channel 14, at least four ingates 15 are evenly distributed circumferentially.

[0033] In this embodiment, eight ingates 15 are arranged on both sides of the annular horizontal sprue 14, forming an enclosed, bottom-injection pouring mode that ensures stable water entry and prevents sand erosion. At the same time, the outlet end of the ingate 15 is embedded in the casting sand core for the same purpose, working together to ensure that the casting is completed as uniformly and synchronously as possible in the cavity, which is more conducive to the simultaneous solidification of the casting.

[0034] Furthermore, the inner gate 15 has a wide and thin annular cross-section, which can effectively reduce the flow rate of molten iron, reduce the scouring of the sand core, and achieve stable and synchronous filling.

[0035] To ensure the purity of molten iron, a filtration and slag collection unit is arranged on each annular horizontal pouring channel 14. The filtration and slag collection unit includes a ceramic filter block 10 and a slag collection bag 11, which can effectively block and adsorb oxide slag and floating slag in molten iron.

[0036] Based on the above structure, to facilitate post-processing, two square dividing blocks (not shown in the figure) are set on the horizontal pouring channel downstream of the filter slag collection unit, so that the pouring system can be neatly broken at this point during cleaning, which facilitates the separation of the pouring channel during post-processing.

[0037] In this invention, the preferred material for the rotary casting is low-temperature, high-toughness ductile iron QT400-18L. To ensure the casting's excellent performance, especially under low-temperature conditions, this invention strictly controls the smelting composition and microstructure, as follows: Firstly, key element control is crucial: to meet the requirements for low-temperature impact toughness, the control of P and Si is particularly important. Specifically, P ≤ 0.02% forms phosphorus eutectic, improving the fluidity of molten iron; Si ≤ 2.2% is used to strengthen ferrite, improve toughness, and suppress white cast iron formation.

[0038] Secondly, trace element control is crucial: Cu≤0.05% improves the product's corrosion resistance; Ni≤0.0056% homogenizes the matrix structure and improves low-temperature toughness; Cr≤0.02% refines graphite, increasing hardness and wear resistance; Mo≤0.01% inhibits the decomposition of pearlite and improves strength.

[0039] Furthermore, the microstructure and performance are guaranteed: the spheroidization rate of the casting is ≥90%, and the number of graphite nuclei is increased by controlling the inoculation process, with an inoculation amount of 0.05%. The graphite morphology is mainly type V or VI, and the graphite size is 5-7 grades.

[0040] The measured mechanical properties of the casting obtained are as follows: tensile strength Rm≥380MPa; yield strength RP0.2≥230MPa; elongation after fracture A≥15%; and its low-temperature impact energy (V-notch) at -20℃ meets the following requirements: single value>9J, average value>12J, which fully meets the requirements for low-temperature high toughness.

[0041] The working principle of the riser and casting system of this utility model suitable for rotary castings is as follows: During casting, molten iron enters the annular horizontal gating system through the straight gating system. After being purified by the slag collection unit, it smoothly and synchronously fills the mold cavity from the bottom through eight evenly distributed wide and thin ingates. During the solidification process of the casting, the bottom chill and the side chill guide it to solidify from bottom to top and from far to near; at the same time, the sand riser located inside the casting cavity is kept solidified last by the action of the heat-insulating riser sleeve, and the casting is fully fed through two independent feeding chambers; By fully feeding the aforementioned QT400-18L ductile iron castings, high-quality castings with dense structure, excellent mechanical properties, and low-temperature impact toughness without shrinkage defects were finally obtained.

[0042] This utility model features a built-in isolation sand core riser separation and cleaning process that is highly efficient and safe, with minimal damage to the casting body. It is suitable for medium to large-sized rotary castings. The specific operation procedure is as follows: Preliminary preparation: After the casting has cooled, first remove any residue from the gating system; Pre-drilling: Use a radial drilling rig to quickly pre-drill holes on both sides of the riser neck to provide a subsequent fracture control path; Gravity upsetting: Subsequently, by using a specific upsetting hammer to strike the casting with gravity, combined with the stress concentration effect of pre-drilled holes and the natural fracture surface formed by pre-embedded partition sand cores, the riser can be quickly and neatly separated from the casting along a predetermined path.

[0043] Compared to traditional methods that rely entirely on manual grinding or gas cutting for separation, this semi-automated separation process increases post-processing efficiency to over 90%. This method is not only highly efficient but also effectively avoids defects such as casting damage, inclusions of filler material, or over-grinding that occur with traditional methods, significantly improving operational safety.

[0044] The beneficial effects of this utility model on risers and casting systems suitable for rotary castings are: Highly efficient feeding: The built-in partitioned sand core riser, combined with the through-hole insulation sleeve, forms an efficient thermal junction and feeding channel, ensuring a good feeding effect; High post-processing separation efficiency: By utilizing the pre-set fracture surface of the partition sand core, the riser and casting are quickly and neatly separated, and the post-processing efficiency is increased to over 90%. This avoids the scrap problems such as damage, inclusion of material, and over-grinding that are easily caused by traditional manual grinding, thereby reducing production costs. Stable and synchronous filling: Through the outer ring, bottom pouring pouring system, the molten iron is filled in a stable and synchronous manner, which effectively avoids casting defects such as shrinkage porosity, sand holes, cold shuts and gas holes that are common in traditional processes; Performance enhancement: By combining precise control of the composition of ductile iron QT400-18L and optimizing the inoculation process, the castings maintain a high spheroidization rate and excellent graphite morphology while enhancing their low-temperature impact toughness, wear resistance and corrosion resistance, meeting the requirements for low-temperature and high-toughness applications. High versatility: Taking rotary castings as an example, the built-in isolation riser and the outer annular bottom pouring system can be widely used in the production of various medium and large castings with complex structures, high quality requirements and special performance requirements, and has broad application prospects.

[0045] The above description is merely an embodiment of this utility model and does not limit the patent scope of this utility model. Any equivalent structural or procedural transformations made using the content of this utility model specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this utility model.

Claims

1. A riser suitable for rotary castings, characterized in that, include: Base sand core, sand riser, partition sand core and insulation riser sleeve, The base sand core is set inside the cavity of the casting. The sand riser is formed on the base sand core and communicates with the cavity of the casting through the riser neck. The partition sand core is embedded inside the sand riser. The bottom of the partition sand core is positioned and matched with the base sand core, and divides the inner cavity of the sand riser into at least two independent feeding chambers. The heat insulation riser sleeve is fitted on the outside of the sand riser.

2. The riser suitable for rotary castings according to claim 1, characterized in that, The partition sand core has a trapezoidal structure, and the bottom of the partition sand core is positioned by a positioning protrusion on it and a positioning groove on the base sand core.

3. The riser suitable for rotary castings according to claim 1, characterized in that, The sand riser has an elliptical trapezoidal platform structure.

4. The riser suitable for rotary castings according to claim 1, characterized in that, The insulating riser sleeve is a through-hole elliptical cylindrical structure that is adapted to the outer contour of the sand riser.

5. The riser suitable for rotary castings according to claim 1, characterized in that, The sand riser includes a riser neck that communicates with each feeding chamber, and the riser neck is funnel-shaped.

6. The riser suitable for rotary castings according to claim 5, characterized in that, Side chills are laid diagonally on both sides of the riser neck, and a ring of bottom chills is also laid on the bottom end face of the casting. The side chills and bottom chills work together to guide the casting to solidify.

7. A casting system, characterized in that, include: The riser suitable for rotary castings as described in any one of claims 1-6, and the annular gating mechanism. The annular pouring mechanism includes a sprue, an annular runner, and multiple ingates. The annular runner is symmetrically connected to the bottom of the sprue and surrounds the casting. The multiple ingates are evenly distributed along the inner circumference of the annular runner, forming a structure for injecting molten iron from the bottom of the casting.

8. The casting system according to claim 7, characterized in that, The ingate has a wide and thin annular cross-section, and there are at least eight in number, which are symmetrically and evenly distributed along the annular horizontal runners on both sides.

9. The casting system according to claim 7, characterized in that, Each of the annular horizontal pouring channels is equipped with a filtration and slag collection unit, which includes a filter block and a slag collection bag.

10. The casting system according to claim 7, characterized in that, The casting material is QT400-18L.

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