Design method for casting and pouring system of large wallboard component

Abstract

The invention belongs to the field of aluminum alloy casting processes, and relates to a design method of a pouring system for casting a large wallboard component. Firstly, the mold filling process of molten metal is not only driven by pressure in a low-pressure casting machine, but also driven by gravity, the mold filling capacity of the molten metal in the thin-wall structure is enhanced, and complete forming of the thin-wall structure is easy to achieve; secondly, the thick cross gate cannot form a complete whole during casting, so that the non-uniformity of residual stress in the casting process is greatly reduced, and the deformation in the casting process is reduced; and finally, the structure of a pouring system is simplified, modeling and assembling are simplified, a casting mold does not need to be overturned, the workload is reduced, and it is guaranteed that the position of a mold core is stable.

Description

Technical Field

[0001] The invention belongs to the field of aluminum alloy casting technology and relates to a pouring system design method for casting large wall plate-type components. Technical Background

[0002] Large wall panel castings include aircraft landing gear guards, aircraft fuselage boarding doors, cargo compartment doors, and various flat frames. The main manufacturing method for aviation wall panel components is to assemble aluminum alloy machined parts and sheet metal parts by riveting, screwing, etc. The process is complicated, the production cycle is long, and the cost is high. For components with larger contours, the rigidity of components manufactured by this method is poor. Typical structural forms of wall panel components are as follows: Figure 1 As shown, in recent years, with the development of aluminum alloy casting technology, the wall panels can be manufactured by first casting the blank as a whole and then machining it. When using castings, its structural features are as follows:

[0003] 1) The outer surface (aerodynamic surface) is a smooth curved surface, such as Figure 1 As shown in 2 in b; the blank thickness is 12-15mm, the thickness after processing is generally 2.5mm, and the inner surface distribution height is 50-60mm and the thickness is 1.5-2.5mm. Figure 1 As shown in 1 in a.

[0004] 2) On both sides along the length, one side has two protruding lugs, which enable the wall panel to open and close after the hinges are installed, and the other side has 2 to 3 thick bosses for installing the locking mechanism.

[0005] 3) The length varies from 1000mm to 2300mm, and the width varies from 600mm to 800mm.

[0006] Since it replaces the combination of machining and sheet metal, the metallurgical quality and body performance of the casting are required to be high, and it is produced using the precision resin sand mold low-pressure casting process.

[0007] In order to ensure the complete casting and obtain excellent metallurgical quality and mechanical properties of the casting, the conventional casting process adopts a side-standing casting posture, such as Figure 2 As shown in the figure, the slot gating system is distributed on the outer surface and reinforcement ribs of the casting, and the vertical tube in the gating system is located on the cross channel of the bottom pouring gating system. However, this gating system can ensure the complete molding of the outer surface and obtain good metallurgical quality, but the inner reinforcement ribs are difficult to form completely, and the under-casting parts must be repaired by welding to make the shape complete. In addition, this gating system design also has the following problems:

[0008] First, the workload of sand mold assembly is large. When assembling the mold, the main sand mold is placed horizontally, and the core that forms the reinforcement ribs on the reverse side of the casting is placed horizontally in the main sand mold. After being fixed, the whole mold is rotated 90° and placed on the bottom mold of the horizontal runner. The core is easy to loosen during the rotation process, resulting in uneven wall thickness.

[0009] Secondly, after cutting and cleaning, the castings will produce large deformations (5 to 10 mm). These deformations need to be corrected during the heat treatment stage to meet the design requirements. The correction workload is large and the labor intensity is high. Some castings, even after correction, do not meet the design requirements and are scrapped. Summary of the invention

[0010] In view of the problems existing in the design of conventional pouring systems for wall panel castings, the present invention proposes a novel pouring system design method, the purpose of which is to produce hatch castings with complete shape, qualified metallurgical quality and mechanical properties by adopting this pouring system in combination with resin sand mold low-pressure casting, and greatly reduce the deformation of the castings.

[0011] The technical solution of the present invention:

[0012] A casting pouring system design method for a large wall panel component includes the following steps:

[0013] 1) The casting posture is horizontal, with the pneumatic surface facing upward and the rib side facing downward;

[0014] 2) A slot-type pouring system is set on the outside of the pneumatic surface. The pouring system is distributed along the length of the casting with a spacing of 250-300 mm;

[0015] 3) Since the cross-sectional shape of the casting along the width direction is an upward convex arc, the slot-type pouring system is also designed to follow the arc shape, but at the top of the convex arc, the slot-type pouring system is separated with a separation interval of 30 to 40 mm; the pouring system beyond both sides of the casting only retains the vertical tube structure, which is bent downward 40 to 60 mm beyond the edge of the casting, perpendicular to the horizontal plane, and the end of the downward-bent vertical tube exceeds the lowest point of the casting by 80 to 100 mm;

[0016] 4) The bent vertical tube is connected to the side runners on both sides respectively. The side runners are disconnected in the middle position. If they interfere with the vertical tube, they are disconnected near the middle position. The two side runners are then connected together through a main runner. Below the main runner is a gate for low-pressure pouring.

[0017] The slot type runner is arranged on the outer surface and is located just above or near the reinforcing rib.

[0018] The top of each slot type runner is disconnected and 3 to 4 air outlet holes with a diameter of Φ3 to 5 mm are provided.

[0019] The cross-sectional shapes of the side runner and the main runner are both square.

[0020] The slot pouring system consists of a vertical tube and a slot, the slot width δ is 1.5 to 2 times the thickness w of the pneumatic surface of the casting, and the vertical tube diameter D is 3 to 4 times the slot width δ.

[0021] Both ends of the side runner should extend beyond the center of the vertical tube by 100 to 150 mm. The side length l of the side runner section is 1.1 to 1.3 times the diameter of the vertical tube. The side length 2 of the main runner is 1.5 to 1.8 times the diameter of the vertical tube, and the length is the distance between the outer sides of the two upper runners. The gate diameter d is the side length l of the main runner. 主 0.6~0.8 times of the original height, 80~100mm.

[0022] The inner surface of the main runner is painted with heat-insulating paint or a 3mm thick aluminum silicate fiber felt is pasted on the surface and baked to dry.

[0023] A pouring method of the pouring system,

[0024] 1) The siding casting has 2 or 3 pouring gates. When pouring, the pouring gate needs to be directly opposite to the rising liquid nozzle on the low-pressure pouring machine.

[0025] 2) The mold must be preheated. The mold temperature should not be lower than 60°C during pouring, and the maximum temperature should not be higher than 150°C. It is determined according to the size and wall thickness of the casting. The larger the casting and the thinner the wall thickness, the higher the mold temperature, and vice versa.

[0026] 3) During low-pressure pouring, a thermocouple is set on the main runner to measure the temperature change of the molten metal in the runner, such as Fig.10 As shown, when the temperature of the molten metal drops to 20-25°C above the alloy solidus, the pressure maintenance is stopped, and the unsolidified molten metal in the main runner flows back into the crucible to ensure that the main runner is disconnected in the middle.

[0027] The advantages of the present invention are as follows: first, the filling process of the molten metal is not only driven by the pressure in the low-pressure pouring machine, but also by gravity. The filling ability of the molten metal in the thin-walled structure is enhanced, and the complete forming of the thin-walled structure is easy to achieve; second, the thick cross runner cannot form a complete whole during pouring, which greatly reduces the unevenness of the residual stress in the casting process and reduces the deformation in the casting process; finally, the structure of the pouring system is simplified, the modeling and assembly are simplified, the casting mold does not need to be turned over, the workload is reduced, and the stability of the core position is guaranteed. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a typical structural form of wall plate castings, where a is the side with reinforcing ribs and b is the side with the outer surface.

[0029] Figure 2 This is a conventional pouring system design for wall panel castings. A is the slot runner distribution on the side with the reinforcement ribs, and b is the slot runner distribution on the side of the outer surface.

[0030] Figure 3 This is the distribution form of the pouring system for wall panel castings proposed by the present invention.

[0031] Figure 4 It is a schematic diagram of the connection between the slit runner and the cross runner of the present invention.

[0032] Figure 5 It is a schematic diagram of the bending of the slit type runner of the present invention.

[0033] Figure 6 It is the structural dimension of the slot type pouring system of the present invention.

[0034] Figure 7 The front landing gear guard plate casting is shown in the figure. a is the outline size, b is the casting reinforcement rib, and c is the schematic diagram of the casting longitudinal section wall thickness.

[0035] Figure 8 The structure of the pouring system for the front landing gear guard casting is shown in Figure 1. a is the distribution diagram of the casting slit runner, and b is the schematic diagram of the cross runner connection.

[0036] Fig. 9 It is the structural dimension of the slot runner of the front landing gear guard plate.

[0037] Fig.10 Schematic diagram of the location of the thermocouple for measuring the temperature of the main runner.

[0038] In the figure, 1 is the reinforcement rib of the casting, 2 is the outer surface of the casting, 3 is the vertical tube, 4 is the low-pressure pouring gate, 5 is the runner, 6 is the temperature measuring thermocouple, 7 is the side runner, 8 is the main runner, 9 is the gap, and 10 is the lug. DETAILED DESCRIPTION

[0039] The present invention is further described below in conjunction with the accompanying drawings and embodiments:

[0040] The distribution form of the pouring system is as follows Figure 3 The details are as follows:

[0041] The casting is poured in a horizontal position with the pneumatic surface facing upward and the rib side facing downward.

[0042] A slot-type pouring system is arranged on the outside of the pneumatic surface. The pouring system is distributed along the length direction of the casting with a spacing of 250 to 300 mm. The specific position should be arranged just above or near the reinforcing ribs.

[0043] like Figure 3As shown, the bent vertical tube 3 is connected to the side runners 7 on both sides respectively, and the side runners are disconnected at the middle position. If they interfere with the vertical tube, they are disconnected at a position close to the middle. The cross-sectional shape of the side runner is a square.

[0044] like Figure 4 As shown, the two side runners 7 are connected together by a main runner 8, and the cross-sectional shape of the main runner is also square; the low-pressure pouring gate 4 is located below the main runner.

[0045] like Figure 5 As shown in the figure, since the cross-sectional shape of the casting along the width direction is an upward convex arc, the slot-type pouring system is also designed to follow the arc shape, but at the top of the upward convex arc, the slot-type pouring system is separated, and the separation interval is 30-40 mm; the pouring system beyond the two sides of the casting only retains the vertical tube structure, which is bent downward 40-60 mm beyond the edge of the casting, perpendicular to the horizontal plane, and the end of the downward-bent vertical tube 3 exceeds the lowest point of the casting by about 80-100 mm, and the diameter d of the low-pressure pouring port 4 is the side length l of the main cross runner 主 0.6~0.8 times of the original height, 80~100mm.

[0046] like Figure 6 As shown, the slot pouring system consists of a vertical tube 3 and a slot 9. The slot width δ is 1.5 to 2 times the thickness w of the aerodynamic surface of the casting, and the vertical tube diameter D is 3 to 4 times the slot width δ. Both ends of the side runner 7 should extend 100 to 150 mm beyond the center of the vertical tube. The side length of the side runner section is l 侧 1.1 to 1.3 times the diameter of the vertical tube; the side length of the main runner 8 is l 主 It is 1.5 to 1.8 times the diameter of the vertical tube, and its length is the distance between the outer sides of the two upper side runners.

[0047] During low-pressure pouring, a thermocouple is set on the main runner to measure the temperature change of the molten metal in the runner. Figure 5 As shown in Figure 6, when the temperature of the molten metal drops to 20-25°C above the alloy solidus, the pressure maintenance is stopped, and the unsolidified molten metal in the main runner flows back into the crucible to ensure that the main runner is disconnected in the middle.

[0048] Example

[0049] The appearance structure of the front landing gear guard plate casting of a certain type of aircraft is as follows Figure 7 The casting is 2100mm long, 600mm wide, 12mm thick in the pneumatic profile, 50mm high and 2.5mm thick in the inner reinforcement ribs; there are 3 lugs on the inner side for installing hinges for opening and closing the guard plate, and the maximum height of the lugs is 280mm.

[0050] According to the present invention, the pouring system structure and distribution of the front landing gear guard plate casting are as follows: Figure 8 shown.

[0051] The specific dimensions of the front landing gear guard casting system are as follows:

[0052] 1) Distribution of pneumatic surface slot runner

[0053] like Figure 8 As shown in a, the casting length is 2100mm, the inner reinforcement ribs are composed of 6 grids along the length direction, each grid is 300mm, and the slot runners are distributed on the transverse reinforcement ribs, a total of 7 locations, with a spacing of 300mm, which are also located just above the 3 lugs.

[0054] 2) Distribution of side runner and main runner

[0055] like Figure 8 As shown in a, the side runner 7 is divided into two sections, the purpose of which is to reduce the large residual stress generated by the thick runner after solidification and cooling. The shorter runner connects three vertical tubes 3, and the longer runner connects four vertical tubes 3; Figure 8 As shown in b, the side runners are connected to the main runners 8, there are two main runners in total, and a low-pressure pouring gate 4 is set in the middle of the main runners.

[0056] 3) Slot runner size

[0057] like Fig. 9 As shown in the figure, the slot runner consists of a vertical tube 3 and a slot 9. The thickness of the pneumatic surface of the casting is 12 mm, and the slot width δ is 1.5 times the thickness of the curved surface at that location, which is 18 mm. The diameter D of the vertical tube is 3 times the slot width δ, i.e. 54 mm, and the distance between the vertical tube and the curved surface of the casting is set at 50 mm. The vertical tube extends to both sides and then goes vertically downward, and the downward distance is 100 mm lower than the lowest point of the lug. Figure 8 As shown in a.

[0058] 4) Side runner and main runner dimensions

[0059] like Fig.10 As shown, the cross section of the side runner 7 is a square with a side length of l 侧 It is 1.1 times the diameter of the vertical cylinder, that is, 60mm. The cross section of the two main runners 8 is a square with a side length of l 主 It is 1.5 times the diameter of the vertical cylinder, that is, 81mm.

[0060] 5) Low pressure gate size

[0061] like Fig.10 As shown, the low-pressure pouring gate 4 is circular, with a diameter equal to the side length l of the main cross runner section. 主 0.8 times of that, which is 65mm, and the height is 80mm.

[0062] The above pouring system is adopted, chiller is placed in the local thick area, the casting mold is a resin sand casting mold, and the low-pressure pouring process parameters are shown in Table 1. During pouring, a temperature measuring thermocouple is set on the main cross runner, the alloy material is ZL114A, and the solidification temperature range of the alloy is 550-610℃. When pouring, when the temperature measured by the thermocouple is 570℃, the pressure holding is stopped.

[0063] After cleaning, the poured castings were inspected by X-ray. The metallurgical quality of the castings reached the level of HB963 Class I parts. The thin-walled reinforcement ribs of the castings were fully formed. The maximum deformation of the castings was 2mm, which fully met the requirements of the technical indicators.

[0064] Table 1 Low pressure casting process parameters of front landing gear guard plate casting

[0065]

Claims

1. A casting pouring system design method for large wall panel components, characterized in that: The following steps are involved: 1) The casting posture is horizontal, with the pneumatic surface facing upward and the rib side facing downward; 2) A slot-type pouring system is set on the outside of the pneumatic surface. The pouring system is distributed along the length of the casting with a spacing of 250-300 mm; 3) Since the cross-sectional shape of the casting along the width direction is an upward convex arc, the slot-type pouring system is also designed to follow the arc shape, but at the top of the convex arc, the slot-type pouring system is separated with a separation interval of 30 to 40 mm; the pouring system beyond both sides of the casting only retains the vertical tube structure, which is bent downward 40 to 60 mm beyond the edge of the casting, perpendicular to the horizontal plane, and the end of the downward-bent vertical tube exceeds the lowest point of the casting by 80 to 100 mm; 4) The bent vertical tube is connected to the side runners on both sides respectively. The side runners are disconnected in the middle position. If they interfere with the vertical tube, they are disconnected near the middle position. The two side runners are then connected together through a main runner. Below the main runner is a gate for low-pressure pouring.

2. The casting pouring system design method for large wall panel components according to claim 1 is characterized in that: The slot type runner is arranged on the outer surface and is located just above or near the reinforcing rib.

3. The casting pouring system design method for large wall panel components according to claim 1 is characterized in that: 3 to 4 vent holes with a diameter of Φ3 to 5 mm are opened at the disconnected position of the top of each slit-type runner.

4. The casting pouring system design method for large wall panel components according to claim 1 is characterized in that: The cross-sectional shapes of the side runner and the main runner are both square.

5. The casting pouring system design method for large wall panel components according to claim 1 is characterized in that: The slot pouring system consists of a vertical tube and a slot, the slot width δ is 1.5 to 2 times the thickness w of the pneumatic surface of the casting, and the vertical tube diameter D is 3 to 4 times the slot width δ.

6. The casting pouring system design method for large wall panel components according to claim 1 is characterized in that: Both ends of the side runner should extend beyond the center of the vertical tube by 100 to 150 mm. The side length l of the side runner section is 1.1 to 1.3 times the diameter of the vertical tube. The side length 2 of the main runner is 1.5 to 1.8 times the diameter of the vertical tube, and the length is the distance between the outer sides of the two upper runners. The gate diameter d is the side length l of the main runner. 主 0.6~0.8 times of the original height, 80~100mm.

7. The casting pouring system design method for large wall panel components according to claim 1 is characterized in that: The inner surface of the main runner is painted with thermal insulation paint or a 3mm thick aluminum silicate fiber felt is pasted on the surface and baked dry.

8. The casting pouring system design method for large wall panel components according to claim 1 is characterized in that: The pouring method of the pouring system comprises the following steps: 1) The wall plate casting has 2 or 3 pouring gates. When pouring, the pouring gate needs to be directly opposite to the liquid riser on the low-pressure pouring machine; 2) The mold must be preheated. The mold temperature should not be lower than 60°C during pouring, and the maximum temperature should not be higher than 150°C. It should be determined according to the size and wall thickness of the casting. The larger the casting and the smaller the wall thickness, the higher the mold temperature, and vice versa. 3) When the parts are poured at low pressure, a thermocouple is set on the main runner to measure the temperature change of the molten metal in the runner; when the molten metal temperature drops to 20-25°C above the alloy solidus, the pressure is kept, and the unsolidified molten metal in the main runner flows back to the crucible to ensure that the main runner is disconnected in the middle.

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