Method for breaking off a gating channel of an investment precision cast part

Abstract

This invention discloses a method for vibrating and breaking the gate of a precision investment casting, which includes, in sequence, a forming process of a casting mold head and a casting wax model, a tree-building process of fixing the casting wax model on the casting mold head, a shell-making and wax-melting firing process, a forming process of pouring liquid metal into the casting mold shell to obtain a mold head and a casting blank with a connecting part, and a vibrating and breaking process of separating the casting blank from the casting mold head. The forming process of the casting wax model involves pressing wax material into a cavity set in a metal mold, cooling and removing the casting wax model. During the forming process of the casting wax model, a connecting part cavity connected to the casting wax model cavity needs to be set in the casting wax model cavity set in the metal mold. After cooling and removal, a casting wax model with a connecting part is formed, and an easily breakable recess is formed on the connecting part, which can be separated from the casting by vibration.

Description

Technical Field

[0001] This invention relates to the field of investment casting technology, specifically to a method for vibrating and breaking the gate of an investment casting. Background Technology

[0002] Investment casting, also known as lost-wax casting, uses wax to create a pattern. Several layers of refractory material are then coated onto the pattern to form a shell. The pattern is then melted and removed from the shell, resulting in a mold without a parting line. After high-temperature firing, the casting can be poured. Upon cooling, the desired casting is produced. To improve casting efficiency, multiple casting wax patterns are often connected to a mold head wax pattern to form a wax pattern assembly. This allows for final pouring, and after cooling, multiple castings are obtained. At this point, the castings are attached to the mold assembly, requiring cutting to separate them. However, the cutting process is cumbersome, easily damaging the casting. Furthermore, the cutting position cannot be kept perfectly consistent, resulting in varying sizes of mold residue remaining on the castings. This leads to inconsistent polishing levels and affects processing efficiency.

[0003] like Figure 1 As shown, Chinese Patent No. 201920339673.8 discloses a casting vibration breaking mechanism for separating a casting 3 from a mold head 1. The mold head 1 includes a mounting groove 11 and a main connecting rod 12 fixedly connected to the mounting groove 11. The main connecting rod 12 is provided with multiple parallel branch connecting rods 13. The tail of each branch connecting rod 13 is fixedly connected to the casting 3. A vibration breaking gate 14 is provided between the branch connecting rod 13 and the casting 3. The vibration breaking gate 14 is configured as a V-shaped vibration breaking groove 141 and is symmetrically arranged on both sides of each branch connecting rod 13. This patent installs the vibrating rod of the vibration drive mechanism 2 in the mounting groove 11 of the mold head 1, causing the vibrating rod of the vibration drive mechanism 2 to drive the mold head 1 to vibrate. The V-shaped vibration groove 141 makes the casting 3 at the tail of the branch connecting rod 13 vibrate with a large amplitude and high frequency, so that the casting 3 can automatically fall off the mold head 2, which improves the processing efficiency to a certain extent. However, this vibration separation method still has the following defects:

[0004] 1. In order to stand the module upright on the workbench or the ground during vibration separation, so that the module mounting groove 11 faces upward, the patent adopts a method of setting a casting plate on the free end of the mold head assembly away from the mold head mounting groove 11. This vibration separation method increases the material cost of investment casting and causes waste.

[0005] 2. When the casting breaks off due to vibration, the vibration rod of the vibration drive mechanism 2 is placed into the mounting groove 11 of the mold head. However, it is easy to slip during vibration, and the vibration rod can easily cause the mold head to tilt during vibration, thereby reducing the vibration breaking efficiency. At the same time, in order to make the vibration rod better connected to the mounting groove, the end of the vibration rod that is placed into the mounting groove 11 is provided with a pointed cone end. This vibration breaking connection method causes the pointed cone end of the vibration rod to get stuck into the mounting groove 11 under repeated vibration, making it difficult to remove.

[0006] 3. The structural design of the V-shaped vibration break groove 141 is unreasonable. The V-shape forms a sharp point in the wax injection mold, which is easy to wear. The mold shell also has a sharp point at this point, which is also easy to be washed away under the scouring of molten metal. Both of these factors increase the thickness of the minimum connection point, and the phenomenon of individual castings failing to break and falling off often occurs.

[0007] 4. The vibration-damped gate 14 is located on the side of the branch connecting rod 13 near the center point of the casting 3. In this way, after the casting is shaken, a section of the branch connecting rod 13 will remain on the casting. Subsequently, it is necessary to use a grinding tool to grind away the remaining section of the branch connecting rod 13, which increases the subsequent processing cost of the casting and is time-consuming and labor-intensive.

[0008] 5. By setting the cast plate to make hard contact with the worktable, the module is easy to slip between the module and the worktable. Summary of the Invention

[0009] Therefore, in view of the above problems, the present invention proposes a vibration method for separating investment castings from the mold head.

[0010] To achieve the above objectives, the technical solution of the present invention provides a method for vibrating and breaking the gate of a precision investment casting, which includes, in sequence, a forming process of a casting mold head and a casting wax model, a tree-building process of fixing the casting wax model on the casting mold head, a shell-making and wax-melting firing process, a forming process of pouring liquid metal into the casting mold shell to obtain a mold head and a casting blank with a connecting part, and a vibrating and breaking process of separating the casting blank from the casting mold head. The forming process of the casting wax model involves pressing wax material into a cavity set in a metal mold, cooling and removing the casting wax model. During the forming process of the casting wax model, a connecting part cavity connected to the casting wax model cavity needs to be set in the casting wax model cavity set in the metal mold. After cooling and removal, a casting wax model with a connecting part is formed, and an easily breakable recess is formed on the connecting part, which can be separated from the casting by vibration.

[0011] The vibration breakage process includes: a rotation and fixation process and a vibration separation process. The rotation and fixation process involves rotating the prepared mold head and the casting blank by 180 degrees so that the cup gate of the casting mold head faces downward. The end of the casting mold head away from the cup gate is connected to the vibration machine using a vibration connecting rod. The end of the vibration connecting rod connected to the mold head is provided with a U-shaped locking groove. During vibration, the U-shaped locking groove engages with the casting rod of the casting mold head to achieve vibration connection. The opening angle of the U-shaped locking groove is 10-30 degrees.

[0012] In the vibration separation process, under a predetermined vibration, the fragile recesses at the connecting parts of each casting break, causing the casting to separate from the connecting parts, thus obtaining each casting blank.

[0013] A further improvement is that the easily breakable recess is located near the casting blank.

[0014] A further improvement is that the cross-section of the connecting part gradually decreases towards the casting blank, forming an inverted trapezoidal structure, and the easily broken recess includes trapezoidal recesses respectively provided on the upper and lower sides of the connecting part and symmetrically arranged.

[0015] Further improvements include: the right opening angle b of the trapezoidal recess near the casting blank is 20-50 degrees; the distance from the right opening to the outside of the casting is 0.5-2mm; the width c from the vertex of the left opening to the vertex of the right opening of the trapezoidal recess is 1-3mm; the single-sided recess depth of the trapezoidal recess is one-quarter to two-fifths of the thickness of the connecting part; and the vertex of the left opening of the trapezoidal recess is provided with a radius of R0.5-2mm.

[0016] A further improvement is made in the tree-building process: the connecting part of the casting wax model is fixed to the casting mold head by heating, and the wax model group is formed on the casting mold head.

[0017] A further improvement is made in the shell-making, wax melting, and baking process, in which the wax mold group obtained in the tree-making process is repeatedly immersed in a slurry prepared with binder and refractory powder, and refractory granules are evenly sprinkled on the surface after each removal to form a hardened film shell on the surface of the wax mold group. Then, the wax mold group with the film shell is heated at high temperature to perform a melting and dewaxing operation, so that the wax mold melts and flows out from the gate to form a casting cavity, and a casting film shell is obtained after baking.

[0018] A further improvement is that an anti-slip pad is placed between the casting mold head and the worktable of the vibratory machine.

[0019] A further improvement is that the anti-slip mat is a rubber mat.

[0020] The present invention has the following beneficial effects:

[0021] 1. By setting a trapezoidal recess and providing a rounded corner (R) at the apex of the left opening of the trapezoidal recess, the cross-section of the connecting part of the casting gradually decreases towards the casting blank, forming an inverted trapezoidal structure. This structure not only increases the pouring flow rate during casting and prevents the molten metal from solidifying due to a slow flow rate, but also allows the casting and the connecting part to be easily separated at a uniform separation position. Consequently, the casting basically does not need to be polished afterward, greatly reducing the polishing work after the casting is shaken apart and significantly improving production efficiency.

[0022] 2. The U-shaped locking groove design solves the problem of the traditional vibrating rod's pointed tip getting stuck in the installation groove and being difficult to remove, reducing the chance of vibration slippage. In addition, the opening angle of the U-shaped locking groove is 10-30 degrees, which makes the casting mold head fit tightly and easy to remove, improving vibration breakage efficiency.

[0023] 3. An anti-slip pad is placed between the casting mold head and the worktable of the vibrator to prevent slippage between the mold and the worktable, reduce safety hazards, and improve vibration efficiency. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of a casting vibration breakage mechanism;

[0025] Figure 2 This is a schematic diagram of the casting mold head.

[0026] Figure 3 This is a schematic diagram of the wax module structure;

[0027] Figure 4 Cross-sectional view of the easily broken depression Figure 1 ;

[0028] Figure 5 This is a schematic diagram of the vibration connection rod.

[0029] Figure 6 Diagram showing the usage status of the vibration connection rod;

[0030] Figure 7 Cross-sectional view of the easily broken depression Figure 2 . Detailed Implementation

[0031] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings and examples. The following examples are only used to more clearly illustrate the technical solutions of the present invention and should not be construed as limiting the scope of protection of the present invention.

[0032] refer to Figures 1 to 6As shown, a method for breaking the gate of a precision investment casting includes, in sequence, a forming process of a casting mold head 10 and a casting wax model 20, a tree-assembly process of fixing the casting wax model 20 onto the casting mold head 10, a shell-making and wax-melting firing process, a forming process of pouring liquid metal into the casting mold shell to obtain a mold head and a casting blank with a connecting part, and a breaking process of breaking the casting blank from the casting mold head.

[0033] The forming process of the casting wax model 20 is to press wax material into the cavity set in the metal mold, cool and remove the casting wax model 20; when forming the casting wax model 20, a connecting cavity connected to the casting wax model cavity needs to be set in the casting wax model cavity set in the metal mold at the same time, and the casting wax model 20 with the connecting part 30 is formed after cooling and removal, and a fragile recess is formed on the connecting part 30 that can be separated from the casting by vibration.

[0034] The assembly process of fixing the casting wax model 20 onto the pouring mold head 10 involves heating and fixing the connecting parts of each casting wax model onto the pouring mold head, and then assembling them on the pouring mold head to form a wax model assembly.

[0035] In the shell-making, wax melting, and baking process, the wax model obtained in the tree-building process is repeatedly immersed in a slurry made of binder and refractory powder. After each removal, refractory granules are evenly sprinkled on the surface to form a hardened film shell on the surface of the wax model. The wax model with the film shell is then heated at high temperature to perform a melt-wax removal operation, causing the wax model to melt and flow out from the gate to form a casting cavity. After baking, a casting film shell is obtained.

[0036] The forming process of pouring liquid metal into a casting mold shell to obtain a mold head and a casting blank with a connecting part is as follows: the liquid metal is poured into the casting mold shell, the liquid metal is injected from the mold head shell of the casting mold shell, the liquid metal flows in sequentially from the mold head shell, and flows through the connecting parts of each casting shell of the casting mold shell to the casting shell. After the liquid metal cools and solidifies, it forms a mold head connected together and a casting blank with a connecting part 30.

[0037] The vibration separation process includes: a rotation and fixation process and a vibration separation process. The rotation and fixation process involves rotating the mold head and the casting blank by 180 degrees, so that the gating gate of the casting mold head faces downwards. The end of the casting mold head away from the gating gate is connected to a vibrating machine (not shown in the figure) using a vibration connecting rod 50. The end of the vibration connecting rod 50 connected to the mold head is provided with a U-shaped locking groove 60. During vibration, the U-shaped locking groove 60 engages with the casting rod of the casting mold head 10, thereby achieving vibration connection. A non-slip pad 70 can also be placed on the vibrating machine at the location of the gating gate of the casting mold head to increase the friction between the gating gate of the casting mold head and the vibrating machine, preventing the casting mold head from slipping during vibration. In this embodiment, the anti-slip pad 70 is preferably made of rubber. To improve vibration efficiency and reduce the probability of vibration slippage, the opening angle of the U-shaped locking groove is 10-30 degrees. The U-shaped locking groove solves the problem that the pointed end of the traditional vibration rod will get stuck in the installation groove and be difficult to remove, thus reducing the probability of vibration slippage. In addition, the opening angle of the U-shaped locking groove is 10-30 degrees, which makes the casting mold head fit tightly and easy to remove, improving vibration breakage efficiency. In this embodiment, the opening angle of the U-shaped locking groove is 10 degrees. A rounded corner can also be provided at the opening end of the U-shaped locking groove to reduce the possibility of the vibration connecting rod 50 breaking due to continuous collision with the casting mold head during vibration.

[0038] In the vibration separation process, under the predetermined vibration action, the fragile recesses of the connecting parts on each casting break, so that each casting blank is separated from the connecting part, and each casting blank is obtained. The casting blanks are cleaned to remove the residual shell and polished to finally obtain the desired casting.

[0039] To reduce the grinding work after the casting is shaken apart, the easily breakable recess is located near the casting blank; such as Figure 4 As shown in the embodiment, the cross-section of the connecting part gradually decreases towards the casting blank, forming an inverted trapezoidal structure. This structure can increase the pouring flow rate during casting to prevent the molten metal from solidifying during the pouring process. The cross-section of the connecting part can also be as shown in the figure. Figure 7 The elongated shape shown;

[0040] The easily breakable recess includes trapezoidal recesses 40 symmetrically arranged on the upper and lower sides of the connecting part. The structure of the trapezoidal recesses 40 symmetrically arranged on the upper and lower sides is the most easily broken by vibration. The angle b of the right opening of the trapezoidal recess 40 is 42 degrees, and the distance d from the vertex of the right opening of the trapezoidal recess to the outer side of the casting is 1 mm. This design prevents shrinkage cavities and porosity of the trapezoidal recess 40 during casting, avoiding defects in the casting. Furthermore, this opening angle reduces the strength of the trapezoidal recess 40 near the casting blank, making the easily breakable recess more likely to break under predetermined vibration.

[0041] The width c from the apex of the left opening to the apex of the right opening of the trapezoidal recess is 1.5mm. The single-sided recess depth of the trapezoidal recess is one-quarter to two-fifths of the thickness of the connecting part. In this embodiment, the thickness of the connecting part is 7mm, and the single-sided recess depth of the trapezoidal recess is 2mm. Therefore, the single-sided recess depth of the trapezoidal recess is two-sevenths of the thickness of the connecting part. This ensures that the fragile recess does not break during the casting process, while also allowing it to break under a predetermined vibration. The apex of the left opening of the trapezoidal recess is provided with a rounded corner of R0.5-2mm. In this embodiment, the rounded corner R of the apex of the left opening is 1mm. By providing a rounded corner at the apex of the left opening, stress concentration at the left opening can be avoided. However, no rounded corner is provided at the apex of the right opening, which will generate a large internal stress during vibration, making it particularly prone to stress cracking. Therefore, the rounded corner at the apex of the left opening ensures that the breakage occurs at the apex of the right opening.

[0042] Based on the aforementioned technical solution, the objective of this invention can be achieved as long as the right opening angle b of the trapezoidal recess near the casting blank is between 20 and 50 degrees, the distance from the right opening to the outside of the casting is between 0.5 and 2 mm, and the opening angle of the U-shaped locking groove is between 10 and 30 degrees.

[0043] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions above are merely illustrative of the principles of the present invention. Various changes and modifications can be made to the present invention without departing from its spirit and scope. All such changes and modifications fall within the scope of the present invention as claimed, which is defined by the appended claims and their equivalents.

Claims

1. A method for vibrating and breaking the gate of a precision investment casting, comprising, in sequence, a forming process of a casting mold head and a casting wax pattern, a tree-assembly process of fixing the casting wax pattern onto the casting mold head, a shell-making and wax-melting firing process, a forming process of pouring liquid metal into the casting mold shell to obtain a mold head and a casting blank with a connecting part, and a vibrating and breaking process of separating the casting blank from the casting mold head, characterized in that: The forming process of the casting wax model is to press wax material into the cavity set in the metal mold, cool and remove the casting wax model; when forming the casting wax model, a connecting cavity connected to the casting wax model cavity needs to be set in the casting wax model cavity set in the metal mold at the same time, and the casting wax model is cooled and removed to form a casting wax model with a connecting part, and a fragile recessed part is formed on the connecting part that can be separated from the casting by vibration. The vibration breakage process includes: a rotation and fixation process and a vibration separation process. The rotation and fixation process involves rotating the prepared mold head and the casting blank by 180 degrees so that the cup gate of the casting mold head faces downward. The end of the casting mold head away from the cup gate is connected to the vibration machine using a vibration connecting rod. The end of the vibration connecting rod connected to the mold head is provided with a U-shaped locking groove. During vibration, the U-shaped locking groove engages with the casting rod of the casting mold head to achieve vibration connection. The opening angle of the U-shaped locking groove is 10-30 degrees. In the vibration separation process, under a predetermined vibration, the fragile recesses at the connecting parts of each casting break, causing the casting to separate from the connecting parts, thus obtaining each casting blank.

2. The method for vibrating and breaking the gate of investment casting according to claim 1, characterized in that: The fragile recess is located near the casting blank.

3. The method for vibrating and breaking the gate of investment casting according to claim 1, characterized in that: The cross-section of the connecting part gradually decreases towards the casting blank, forming an inverted trapezoidal structure. The easily broken recess includes trapezoidal recesses respectively provided on the upper and lower sides of the connecting part and symmetrically arranged.

4. The method for vibrating and breaking the gate of investment casting according to claim 3, characterized in that: The trapezoidal recess has a right opening angle b of 20-50 degrees near the casting blank, and the distance from the right opening to the outside of the casting is 0.5-2mm. The width c from the vertex of the left opening to the vertex of the right opening of the trapezoidal recess is 1-3mm. The single-sided recess depth of the trapezoidal recess is one-quarter to two-fifths of the thickness of the connecting part. The vertex of the left opening of the trapezoidal recess has a rounded corner of R0.5-2mm.

5. The method for vibrating and breaking the gate of an investment casting according to claim 1, characterized in that: In the tree-building process, the connecting part of the casting wax model is fixed to the pouring mold head by heating, and the wax model group is formed by tree building on the pouring mold head.

6. The method for vibrating and breaking the gate of an investment casting according to claim 5, characterized in that: The shell-making, melting, and baking process involves repeatedly immersing the wax mold group obtained in the tree-building process into a slurry prepared from binder and refractory powder. After each extraction, refractory granules are evenly sprinkled on the surface to form a hardened film shell on the surface of the wax mold group. The wax mold group with the film shell is then heated at high temperature to perform a melting and dewaxing operation, causing the wax mold to melt and flow out from the gate to form a casting cavity. After baking, a casting film shell is obtained.

7. The method for vibrating and breaking the gate of an investment casting according to claim 1, characterized in that: An anti-slip pad is placed between the casting mold head and the worktable of the vibratory machine.

8. The method for vibrating and breaking the gate of an investment casting according to claim 7, characterized in that: The anti-slip mat is a rubber mat.

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