Riser-free casting structure for V-method casting of ductile iron axle

Abstract

The utility model discloses a ductile iron axle V-method casting riser-free casting structure, an axle casting comprises an axle housing main body and flange parts positioned on two sides of the axle housing main body, a plurality of processing hole sites distributed in the circumferential direction are arranged on the flange parts, and a sand core is arranged in the axle casting; the positions, close to the flange part, of the two sides of the upper portion of the axle housing body are provided with follow-up external chillers. An internal chill is arranged in the sand core and is positioned in the middle of the flange part; an iron wire is arranged at the position corresponding to the machining hole position and is perpendicular to the end face of the flange part. According to the scheme, the ductile iron axle casting can be produced without risers through the V-method process, shrinkage cavities at the machining hole positions of the upper box are reduced, the shrinkage cavities can be accurately reduced by placing iron wires at the machining hole positions in the molding process, the blank quality is effectively improved, the product yield is increased, blank waste products are reduced, the product yield is increased, the machining time is saved, and the production period is shortened. The production cost is reduced.

Description

Technical Field

[0001] This utility model belongs to the field of casting technology, specifically relating to a riser-free casting structure for ductile iron axles using the V-process casting method. Background Technology

[0002] Axles are common automotive components, typically manufactured using ductile iron (DPI). Currently, axle production yields are low, with the main defect being shrinkage porosity in the M20 machining holes on both sides of the upper housing. This results in high casting time and economic costs, and difficulty in meeting supply demands. Shrinkage cavities in DPI refer to the voids formed during the solidification process of ductile iron parts due to uneven volume shrinkage. V-process casting, or vacuum-sealed molding, uses a plastic film to seal the sand box, employing a vacuum pump to extract air from the mold, creating a pressure difference between the inside and outside of the mold. This causes the dry sand to compact, forming the desired cavity. In the existing processes during product development, DPI axle products exhibit numerous shrinkage cavities and low yields. Therefore, for later mass production, it is urgent to improve the casting process to increase productivity and deliver products on time and at the lowest cost. Utility Model Content

[0003] The technical problem to be solved by this utility model is to provide a riserless casting structure for V-process casting of ductile iron axles, which solves the problems of excessive shrinkage cavities and low yield in the existing process. It realizes the riserless casting process by taking specific improvement measures to improve shrinkage cavities and porosity defects, thereby increasing the yield and product yield and reducing production and manufacturing costs.

[0004] According to the technical solution of this utility model, this utility model provides a riser-free casting structure for ductile iron axles using the V-process casting method. The axle casting includes an axle housing body and flange portions located on both sides of the axle housing body. The flange portions have multiple circumferentially distributed machining holes. A sand core is present inside the axle casting. Conformal external chills are provided on both sides above the axle housing body near the flange portions. An internal chill is provided inside the sand core, and the internal chill is located in the middle of the flange portion. Iron wires are provided at the locations corresponding to the machining holes, and the iron wires are perpendicular to the end faces of the flange portions.

[0005] Furthermore, multiple vertically arranged air vents are distributed above the axle casting.

[0006] Furthermore, it also includes a vertical gating section. The axis of the axle casting is transverse. The gating section is located on the front side of the axle housing body of the axle casting. The lower end of the gating section is connected to a transverse runner. The gating section is located in the middle of the runner. Both ends of the runner are connected to the axle casting through an ingate.

[0007] Furthermore, a foam ceramic filter screen is installed at the junction of the horizontal runner and the inner runner.

[0008] Furthermore, the cross-section of the ingate is flat.

[0009] Furthermore, the two ingates are connected to the sides of the axle housing body near the flanges, respectively. The ingates are horizontally positioned and their positions are directly opposite the axis of the axle casting.

[0010] Furthermore, the diameter of the wire is 3.5mm.

[0011] Furthermore, there are seven air outlets, one of which is located in the middle of the axle casting along its axial direction, and the other six are symmetrically arranged on both sides of the axle casting.

[0012] Furthermore, the diameter of the air outlet is 20mm.

[0013] Furthermore, the diameter of the gate is 75mm.

[0014] Compared with the prior art, the beneficial technical effects of this utility model are as follows:

[0015] This utility model relates to a riser-free casting structure for ductile iron axles using the V-process casting method. Utilizing internal and external chilling techniques, it enables riser-free production of ductile iron axle castings using the V-process. The greatest advantage of this utility model lies in its extremely high yield and high pass rate. Furthermore, this utility model reduces shrinkage cavities at the upper molded hole locations. Placing iron wire at the M20 machined hole locations during molding precisely reduces shrinkage cavities, effectively improving blank quality, increasing yield, reducing scrap, improving product yield, saving processing time, shortening the production cycle, and lowering production costs. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the riserless casting structure provided by this utility model.

[0017] Figure 2 This is a structural schematic diagram of the axle casting and the conformal external chill.

[0018] Figure 3 yes Figure 1 The structure shown is a right view with the central sand core hidden.

[0019] Figure 4 yes Figure 3 A schematic diagram of the internal chill placed on the right side of the sand core in the structure shown.

[0020] Figure 5 This is a schematic diagram of the left-side structure of the axle casting.

[0021] Figure 6 This is a structural diagram of a vehicle axle casting with iron wires placed in the machined holes.

[0022] Figure 7 yes Figure 6The right view of the structure shown.

[0023] Explanation of reference numerals in the attached figures:

[0024] 1. Axle casting; 11. Axle housing body; 12. Flange; 13. Machining holes; 2. Sand core; 3. Conformal external chill; 4. Internal chill; 5. Wire; 6. Vent; 71. Sprue; 72. Stream runner; 73. Ingate. Detailed Implementation

[0025] This invention provides a riserless casting structure for ductile iron axles using the V-process casting method, solving the problems of excessive shrinkage cavities and low yield in existing processes. Currently, the low yield of axle products is mainly due to shrinkage porosity in the M20 machining holes on both sides of the upper box. To address this issue, this invention studies and improves the process by placing internal and external chills, and inserting wires into the sand mold at the machining hole locations during molding, and designs a riserless casting structure. When using the improved V-process casting technology for ductile iron axles, the specific measures of this invention can improve shrinkage cavities and porosity defects, achieving a riserless casting process, while simultaneously increasing yield and product yield, and reducing manufacturing costs.

[0026] Please see Figures 1 to 7 This utility model discloses a riser-free casting structure for V-process casting of ductile iron axles, used for producing axle castings. Axles are existing automotive components. Simply put, the axle casting 1 mainly includes an axle housing body 11 and flange portions 12 located on both sides of the axle housing body 11. The flange portions 12 also have multiple circumferentially distributed machining holes 13 (specifically M20 machining holes). Similar to existing technologies, a sand core 2 is included within the axle casting 1 to form a hollow structure.

[0027] The main improvements of this utility model include: conformal external chills 3 (conformal external chills mean that the chills are external chills and conformal chills) are provided on both sides above the bridge housing body 11 near the flange portion 12; an internal chill 4 (more specifically, a conformal internal chill) is provided inside the sand core 2; the internal chill 4 is located in the middle of the flange portion 12 (more specifically, the internal chill 4 has an irregular shape, with a large volume located near the upper machining holes and near the rear heavy / complex structure; the internal chill 4 is provided at least on the right side of the flange portion 12, or, the internal chill 4 is provided on both the left and right sides); and an iron wire 5 is provided at the corresponding machining holes 13 (more specifically, the row of machining holes 13 above), the diameter of the iron wire 5 is, for example, 3.5 mm, and the iron wire 5 is perpendicular to the end face of the flange portion 12; in addition, this solution does not have a conventional riser structure.

[0028] More specifically, a plurality of vertically arranged vents 6 are distributed above the axle casting 1, which are formed through vents in the mold. After the molten iron fills the cavity area, it enters the vents. There are seven vents 6, one of which is located in the middle of the axle casting 1 in the axial direction, and the other six are symmetrically arranged on both sides of the axle casting 1. The vents 6 are generally cylindrical, and the diameter of the vents 6 is, for example, 20 mm. It also includes a vertical gating section 71, which is generally cylindrical and has a diameter of 75mm. The axis of the axle casting 1 is transverse. The gating section 71 is located on the front side of the axle housing body 11 of the axle casting 1. Molten iron is poured from the gating section 71. The lower end of the gating section 71 is connected to a transverse runner 72. The gating section 71 is located in the middle of the runner 72. Both ends of the runner 72 are connected to the axle casting 1 through an inner gating 73, thus forming an integral gating system.

[0029] In some preferred embodiments, a foamed ceramic filter screen is provided at the overlap of the horizontal runner 72 and the ingate 73. Furthermore, the ingate 73 has a flat cross-section. More specifically, the two ingates 73 are respectively connected to the sides of the axle housing body 11 near the flange portion 12. The ingates 73 are horizontally positioned, and their positions are directly opposite the axis of the axle casting 1 (rather than using a pressing-edge overlapping method), thus allowing for smoother molten iron flow and filling.

[0030] The design concept and principle of this utility model are as follows.

[0031] The riserless casting of ductile iron is related to factors such as casting structure, mold characteristics, and gating system. First, let's analyze the characteristics of molten iron. For ductile iron castings, from the moment the molten iron is poured into the mold, it shrinks as the temperature of the molten iron decreases; this is called liquid shrinkage. If austenite is formed during solidification, solidification shrinkage will also occur. If graphite nodules precipitate during the liquid or solidification phase, and since the density of graphite is only about 1 / 3 that of austenite, volume expansion will occur. Therefore, from a static analysis, when the casting modulus is ≥2.5cm, if the sum of the volume shrinkage during liquid cooling and the volume shrinkage during solidification is less than the volume increase due to graphitization expansion, riserless casting of ductile iron can be achieved. (The module of the axle casting in this embodiment is exactly 2.5cm.) To meet the above requirements, the following conditions must be met: a high-rigidity mold should be used, so that the cavity size remains unchanged or changes very little after the molten iron is solidified and sealed at the inlet and outlet; the highest possible carbon equivalent should be used, with appropriate inoculation, to ensure sufficient graphitization and maximize the volume increase of graphitization expansion, without causing graphite floating; multiple ingates should be used to disperse the molten iron into the cavity, and chills should be used to adjust the cooling and solidification of all parts of the casting as simultaneously as possible; a large amount of chills should be used to enhance the cooling of the casting, so that the outer layer of the casting cools and solidifies rapidly after the molten iron enters the cavity, completing part of the shrinkage before the liquid channels in the ingate and the core of the casting solidify and seal, forming a volume gap, and timely obtaining feeding liquid from the liquid channels, increasing the flow rate of the ingate (i.e., increasing the external feeding amount), and improving the feeding effect of the gating system; the pouring temperature should be appropriately reduced to reduce liquid volume shrinkage.

[0032] Based on the above technical requirements and after careful analysis of the actual production situation, it is concluded that the V-process can meet the condition of "high mold rigidity". Other conditions can be designed according to specific circumstances. Therefore, it is considered that the riserless casting process is feasible for this casting.

[0033] Specifically, this invention features an internal chill placed on the right side of the sand core. After the molten iron enters the sand mold, the cooling rate of the molten iron in the internal chill is faster than in other areas, reducing the likelihood of shrinkage defects in the blank at the M20 machining hole. A conformal external chill is placed in the upper box. After the molten iron enters the sand mold, the external chill rapidly cools the molten iron, further reducing shrinkage defects in the blank at the M20 machining hole. A φ3.5mm iron wire is placed at the M20 machining hole. When the wire melts during casting, the temperature of the molten iron at this location is lower than in other areas, resulting in a slightly faster cooling rate and reducing shrinkage at the M20 hole. The upper box of the sand core has no riser; instead, a φ75mm gating gate (straight sprue) and seven φ20 fine vents serve a dual purpose of venting and liquid shrinkage replenishment.

[0034] When casting ductile iron using a riserless process, the mold must be filled smoothly and stably at the lowest possible temperature within the shortest possible time. This invention's gating system employs a center-pour method, dispersing the molten iron into the mold cavity. A foam ceramic filter is placed at the overlap of the runner and ingate, serving not only as a filter but also to moderate the flow rate. After verification, the ingate cross-section was changed to a flat shape to prevent graphite expansion from causing molten iron backflow and to avoid the formation of hot spots. The overlap of the ingate was removed, minimizing the entire casting process. Furthermore, given the thin wall of the casting, the removal of the secondary overlap enhances the fluidity of the molten iron, further shortening the casting time. The temperature drop of the molten iron during casting is minimized, maximizing the reduction of the casting temperature. Combined with the molten metal flow characteristics of the V-process, the casting temperature was updated to 1400±10℃.

[0035] Chills can resolve most shrinkage cavities. Chills essentially reduce the modulus at the shrinkage cavity in the casting, thus mitigating the shrinkage. Chills are chilling agents placed inside, on the surface of, or within the mold cavity to accelerate localized cooling of the casting. They control the solidification sequence of the casting to obtain a qualified casting. Chills do not compensate for shrinkage; they only redirect the shrinkage porosity to other locations. Chills do not reduce the amount of molten iron shrinkage, but through relocation, they can bring the shrinkage closer to or force it to other parts of the casting or the riser area. According to the product quality requirements, as long as there are no shrinkage cavities in the machined holes and surfaces, the requirements are met, which is a prerequisite for using chills. The use of wire for some internal chills is designed in conjunction with the V-process. After using chills, all risers in the original gating system are removed, leaving only the vents required for the V-process. Furthermore, further adjustments to the raw material ratio, molten iron treatment, and chemical composition can be considered. By controlling the composition range and optimizing the smelting process, the shrinkage porosity tendency of the molten iron can be improved, enhancing its self-compensating ability and further eliminating shrinkage porosity.

[0036] In summary, a typical technical solution for the riserless casting structure of the V-process for ductile iron axles of this utility model is as follows: a casting process without risers is achieved by using a conformal external chill in the upper box, an internal chill in the sand core, and placing φ3.5 iron wire in the M20 machined holes; ultimately, this improves the yield of cast products, reduces waste, and shortens the production and delivery cycle; existing casting processes typically use conventional riser pouring, while this utility model achieves riserless pouring and eliminates shrinkage defects in the M20 machined holes; thus solving problems such as low yield and high defect rate.

Claims

1. A riserless casting structure for ductile iron axles using the V-process casting method, characterized in that, The axle casting (1) includes an axle housing body (11) and flange portions (12) located on both sides of the axle housing body (11). The flange portions (12) have multiple circumferentially distributed machining holes (13). The axle casting (1) contains a sand core (2). Conformable external chills (3) are provided on both sides above the axle housing body (11) near the flange portions (12). An internal chill (4) is provided inside the sand core (2) and is located in the middle of the flange portion (12). A wire (5) is provided at the location corresponding to the machining hole (13) and is perpendicular to the end face of the flange portion (12).

2. The riserless casting structure of ductile iron axle cast using the V-method according to claim 1, characterized in that, Multiple vertically arranged air vents (6) are provided above the axle casting (1).

3. The riserless casting structure of ductile iron axle cast using the V-method according to claim 2, characterized in that, It also includes a vertical gating section (71). The axis of the axle casting (1) is transverse. The gating section (71) is located on the front side of the axle housing body (11) of the axle casting (1). The lower end of the gating section (71) is connected to a transverse runner (72). The gating section (71) is located in the middle of the runner (72). Both ends of the runner (72) are connected to the axle casting (1) through an inner runner (73).

4. The riserless casting structure of ductile iron axle cast using the V-method according to claim 3, characterized in that, A foam ceramic filter screen is installed at the joint between the horizontal runner (72) and the inner runner (73).

5. The riserless casting structure of ductile iron axle cast using the V-method according to claim 3, characterized in that, The cross-section of the ingate (73) is flat.

6. The riserless casting structure of ductile iron axle cast using the V-method according to claim 5, characterized in that, Two ingates (73) are connected to the sides of the axle housing body (11) near the flange (12). The ingates (73) are horizontally set and the position of the ingates (73) is directly opposite to the axis of the axle casting (1).

7. The riserless casting structure of ductile iron axle cast using the V-method according to any one of claims 1-6, characterized in that, The diameter of the iron wire (5) is 3.5 mm.

8. The riserless casting structure of ductile iron axle cast using the V-method according to any one of claims 2-6, characterized in that, There are seven air outlets (6), one of which is located in the middle of the axle casting (1) in the axial direction, and the other six are symmetrically arranged on both sides of the axle casting (1).

9. The riserless casting structure of ductile iron axle cast using the V-method according to any one of claims 2-6, characterized in that, The diameter of the air outlet (6) is 20mm.

10. The riserless casting structure of ductile iron axle cast using the V-method according to any one of claims 3-6, characterized in that, The diameter of the gate (71) is 75 mm.

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