A method of investment casting

Abstract

The application discloses a kind of investment casting methods, comprising: investment casting shell can constitute a recess integral, to the alloy metal liquid that pours cup mouth overflows is introduced, and the investment casting shell step of wax removal forming is supplemented to riser area.Due to investment casting shell can constitute a recess integral, to the alloy metal liquid that pours cup mouth overflows is introduced to riser area, supplement to improve the temperature of riser area, delay the solidification time of riser, increase the feeding capacity of riser to casting, effectively avoid the loose defect of casting hot node generation.Meanwhile, due to investment casting shell can constitute a recess integral, to the alloy metal liquid that pours cup mouth overflows is introduced to recess integral, so that the alloy metal liquid that overflows will be collected in the recess integral space of auxiliary tooling part constituted investment casting shell, solve the problem that too much alloy liquid is scattered on pouring table from pouring cup when investment casting shell is filled, reduce the security risk of construction.

Description

Technical Field

[0001] This invention relates to an investment casting method, belonging to the field of investment casting technology. Background Technology

[0002] A casting of a large casing-type investment casting, casting 1, has a structure consisting of an inner ring 11, a support plate 13, and an outer ring 12, as shown in the figure. Figures 1 to 2 As shown, the inner and outer rings have thicker mounting edges 14 at their top and bottom ends, and thinner ring walls with thicker lugs 15 (also called bosses) in the middle of the ring walls. When designing the gating system, a bottom-pouring gating system is generally used. Figure 3 and Figure 4 As shown, the molten alloy enters the bottom runner 23 through the central sprue 22 at the pouring cup 21, and then flows upwards from the mounting edge 14 below the inner ring 11 and outer ring 13 to fill the shell cavity. The flow path is as follows: Figure 3 and Figure 4 The arrow shown finally reaches the riser 24 of the mounting edge 14 above the inner ring 11 and outer ring 13; due to the large size of this type of casting, after designing the bottom-pouring gating system, the wax pattern module (see...) Figure 3 and Figure 4 The structure shown is larger. Since the temperature of the mold shell is much lower than that of the alloy liquid, the mold shell absorbs heat during the pouring and filling process, and the alloy liquid cools down. When the first stream of alloy liquid reaches the riser 24, the temperature of the alloy liquid has been greatly lost. The riser temperature is low and solidification is fast, which is not conducive to feeding the upper mounting edge 14 and lug 15, and can easily lead to shrinkage cavities and porosity defects.

[0003] Although the existing technology (a method for casting aluminum alloys disclosed in Chinese Patent Publication No. CN103736977A, which discloses the technology of setting up a gating system and an atmospheric pressure riser on a sand box) can improve the feeding capacity of the riser 24 by increasing its size and avoiding shrinkage cavities and porosity defects, increasing the riser requires more molten alloy and consumes more metal. At the same time, during the filling of the mold shell, there is a problem that too much molten alloy overflows from the riser and spills onto the pouring platform, which increases the safety hazards during construction. Summary of the Invention

[0004] To solve the above-mentioned technical problems, the present invention provides an investment casting method.

[0005] The present invention is achieved through the following technical solutions.

[0006] The present invention provides an investment casting method, comprising: a dewaxing and forming of an integral groove for the investment mold shell to introduce the molten alloy metal overflowing from the pouring cup into the riser, thereby increasing the temperature of the riser (24) region, and simultaneously collecting and accommodating the molten alloy metal overflowing from the riser and the pouring cup into the integral groove for the investment mold shell.

[0007] The dewaxing molding process specifically involves: heating and melting the entire wax model, pouring out the melted wax model liquid, removing the entire auxiliary tooling since the corresponding bolts of the wax model do not have a wax model structure, and forming the molded mold shell. The inclined boss at the relative riser of the molded mold shell forms a groove that connects to the pouring cup opening. The molded mold shell of the previously auxiliary tooling part forms a groove that connects the tops of all risers and the tops of the pouring cup opening.

[0008] Following the dewaxing and forming of the melt mold shell step, a subsequent alloy liquid pouring step is also included.

[0009] The alloy liquid pouring steps are as follows: After sintering and preheating the mold shell, the alloy liquid is poured in through the pouring cup. The alloy liquid flows from the pouring cup into the mold cavity through the sprue and the gating system, and then flows upward from the mounting edge below the inner and outer rings to fill the mold cavity. Finally, it reaches the riser at the mounting edge above the inner and outer rings. The alloy liquid overflowing from the pouring cup will flow to the riser area. At the same time, the alloy liquid overflowing from the riser and the pouring cup will collect in the groove space formed by the mold shell in the auxiliary tooling part.

[0010] Before the dewaxing and molding of the melt pattern shell, there are three steps that are carried out in sequence: making the casting wax pattern, installing the wax pattern and auxiliary tooling, and making the melt pattern shell.

[0011] The steps for making the casting wax model are as follows: using wax material to make a wax model according to the shape of the casting, the wax model includes two parts: the bottom pouring gating system and the shape of the casting. The bottom pouring gating system consists of a pouring cup, a sprue connected to the pouring cup, and a runner connected to the sprue. The runner is connected to the wax model of the casting shape, and a riser is set on the wax model at the corresponding mounting edge.

[0012] The installation steps of the wax model and auxiliary tooling are as follows: the auxiliary tooling includes an auxiliary cover plate, nuts, and bolts. The bottom of the auxiliary cover plate is a conical surface, and multiple spaced inclined bosses are integrally formed on the conical surface. The middle part of the auxiliary cover plate and the inclined bosses are provided with corresponding installation through holes. The nuts and bolts are fixed to the wax model at the riser and pouring cup mouth of the wax model in the shape of a casting through the installation through holes.

[0013] The steps for making the melting mold shell are as follows: except for the top surface of the auxiliary cover plate of the auxiliary tooling which is not coated with sand, the wax mold of the casting shape and the bottom pouring gating system as well as the auxiliary tooling are all coated with sand to prepare the sand mold shell.

[0014] The beneficial effects of this invention are as follows: Since the mold shell can form a groove as a whole, the molten alloy metal overflowing from the pouring cup will flow to the riser area, replenishing and increasing the temperature of the riser area, delaying the solidification time of the riser, increasing the riser's feeding capacity for the casting, and effectively avoiding porosity defects at the hot joints of the casting. At the same time, the groove as a whole collects and accommodates the molten alloy metal overflowing from the riser and pouring cup, so that the overflowing molten alloy metal will collect in the groove space formed by the mold shell in the auxiliary tooling part, solving the problem of too much molten alloy overflowing from the riser and scattering on the pouring platform during the filling of the mold shell, and reducing the safety hazards of construction. Attached Figure Description

[0015] Figure 1 This is a top view of the casting;

[0016] Figure 2 This is a schematic diagram of the main view section of the casting;

[0017] Figure 3 This is a top view of the wax model consisting of the casting and the bottom-pouring gating system;

[0018] Figure 4 This is a schematic front view cross-section of the wax model, which consists of the casting and the bottom-pouring gating system.

[0019] Figure 5 This is a front sectional view of the auxiliary tooling and wax model being installed as a whole;

[0020] Figure 6 This is a bottom view of the auxiliary cover plate of the auxiliary tooling;

[0021] Figure 7 yes Figure 6 Cross-sectional view along line AA;

[0022] Figure 8 This is a schematic cross-sectional view of the front view of the melt pattern shell;

[0023] In the figure: 1-casting; 11-inner ring; 13-support plate; 12-outer ring; 14-mounting edge; 15-lug; 21-pouring cup opening; 22-sprue; 23-glide runner; 24-riseer; 31-auxiliary cover plate; 32-nut; 33-bolt; 34-sloping boss; 41-molded mold shell; 42-groove integral. Detailed Implementation

[0024] The technical solution of the present invention is further described below, but the scope of protection is not limited to what is described.

[0025] like Figures 1 to 8 As shown.

[0026] This application discloses an investment casting method, comprising the following steps performed sequentially:

[0027] Step 1, making the casting wax model: using wax material to make a wax model according to the shape of casting 1. The wax model includes two parts: the bottom pouring gating system and the shape of casting 1. The bottom pouring gating system consists of a pouring cup 21, a sprue 22 connected to the pouring cup 21, and a runner 23 connected to the sprue 22. The runner 23 is connected to the wax model of the shape of casting 1, and a riser 24 is set on the wax model at the corresponding mounting edge 14.

[0028] Step 2, Installation of wax model and auxiliary tooling: The auxiliary tooling includes auxiliary cover plate 31, nut 32, and bolt 33. The bottom of the auxiliary cover plate 31 is a conical surface, and multiple spaced inclined bosses 34 are integrally formed on the conical surface. The middle part of the auxiliary cover plate 31 and the inclined bosses 34 are provided with corresponding installation through holes. The nut 32 and bolt 33 are fixed to the wax model at the riser 24 and the pouring cup mouth 21 of the wax model in the shape of casting 1 through the installation through holes.

[0029] Step 3, Fabrication of the casting mold shell: Except for the top surface of the auxiliary cover plate 31 of the auxiliary tooling which is not coated with sand, the wax mold of the casting 1 shape part and the bottom pouring gating system as well as the auxiliary tooling are all prepared by coating with sand to create the sand mold shell.

[0030] Step 4, Dewaxing and Molding of the Molded ...

[0031] Step 5, Alloy Molten Metal Pouring: After sintering and preheating the mold shell 41, the alloy molten metal is poured into the pouring cup 21. The alloy molten metal flows from the pouring cup 21 into the sprue 22 and glide sprue 23, flowing upwards from the mounting edge 14 below the inner ring 11 and outer ring 13 to fill the mold cavity. Finally, it reaches the riser 24 above the mounting edge 14 above the inner ring 11 and outer ring 13. The alloy molten metal overflowing from the pouring cup 24 will flow to the riser 24 area. At the same time, the alloy molten metal overflowing from the riser 24 or the pouring cup 21 will collect in the auxiliary process area. Within the space of the groove formed by the partially melted mold shell 41, the problem of excessive alloy liquid overflowing from the riser and scattering onto the pouring platform during the filling of the mold shell is solved, reducing the safety hazards during construction. The alloy liquid flows to the riser 24 through the groove formed by the inclined boss 34 on the mold shell 41 relative to the riser 24. On the one hand, it replenishes the riser 24 with alloy liquid, and on the other hand, it increases the temperature of the alloy liquid in the riser 24, thereby improving the feeding capacity of the riser 24 and reducing the tendency of shrinkage cavities and porosity. Thirdly, it prevents excess alloy liquid from scattering onto the pouring platform.

[0032] Since the mold shell 41 can form a groove 42, the molten alloy metal overflowing from the pouring cup 21 is introduced into the riser 24 to supplement and increase the temperature of the riser 24 area. At the same time, the groove 42 collects and accommodates the molten alloy metal overflowing from the riser 24 or the pouring cup 21. This ensures that the overflowing molten alloy metal will collect in the space of the groove 42 formed by the mold shell 41 in the auxiliary tooling part, which solves the problem of too much molten alloy overflowing from the riser and scattering on the pouring platform during the filling of the mold shell, and reduces the safety hazards during construction.

Claims

1. A method for investment casting, characterized in that, include, The following steps will be performed in sequence: Step 1: The steps for making the casting wax model are as follows: Use wax material to make a wax model according to the shape of the casting (1). The wax model includes two parts: the bottom pouring gating system and the shape of the casting (1). The bottom pouring gating system consists of a pouring cup (21), a sprue (22) connected to the pouring cup (21), and a runner (23) connected to the sprue (22). The runner (23) is connected to the wax model of the shape of the casting (1). A riser (24) is set on the wax model at the corresponding mounting edge (14). Step 2, the installation steps of wax model and auxiliary tooling are as follows: The auxiliary tooling includes auxiliary cover plate (31), nut (32) and bolt (33). The bottom of the auxiliary cover plate (31) is a conical surface. Multiple spaced inclined bosses (34) are integrally formed on the conical surface. The middle part of the auxiliary cover plate (31) and the inclined bosses (34) are provided with corresponding installation through holes. The nut (32) and bolt (33) are fixed to the wax model at the riser (24) and pouring cup mouth (21) of the wax model in the shape of casting (1) through the installation through holes. Step 3, the steps for making the melting mold shell are as follows: except for the top surface of the auxiliary cover plate (31) of the auxiliary tooling which is not coated with paint and sand, the wax mold of the casting (1) shape part and the bottom pouring gating system as well as the auxiliary tooling are all prepared by coating with paint and sand to make the melting mold shell. Step 4, the dewaxing molding process is as follows: heat and melt the entire wax model, pour out the melted wax model liquid, and remove the entire auxiliary tooling corresponding to the wax model bolt (33) since there is no wax model structure, and form the molded mold shell (41). The inclined boss (34) forms a groove in the molded mold shell (41) at the relative riser (24) to connect the pouring cup mouth (21). The molded mold shell (41) of the auxiliary tooling part forms a groove whole (42) that connects the top of all risers (24) and the top of pouring cup mouth (21). The groove (42) introduces the molten alloy metal overflowing from the pouring cup (21) into the riser (24), replenishing and increasing the temperature of the riser (24) area, while collecting and containing the molten alloy metal overflowing from the riser (24) and the pouring cup (21).

2. The investment casting method as described in claim 1, characterized in that: Following the dewaxing and forming of the melt mold shell step, a subsequent alloy liquid pouring step is also included.

3. The investment casting method as described in claim 2, characterized in that, The alloy liquid pouring step is as follows: After sintering and preheating the mold shell (41), the alloy liquid is poured in through the pouring cup (21). The alloy liquid enters from the pouring cup (21) and flows upward from the mounting edge (14) below the inner ring (11) and outer ring (13) through the straight runner (22) and the horizontal runner (23) to fill the mold shell cavity. Finally, it reaches the riser (24) above the mounting edge (14) above the inner ring (11) and outer ring (13). The alloy liquid overflowing from the riser (24) or pouring cup (21) will collect in the space of the groove (42) formed by the auxiliary tooling part of the mold shell (41).

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