An investment casting process for a screw

Abstract

The application discloses a kind of screw's investment casting process, comprising: wax mould forming part has screw wax mould manufacturing step, screw wax mould manufacturing step uses first wax injection mould and support frame, support frame is placed in the cavity of first wax injection mould and wax is injected, obtains first connecting body;Shell forming part has shell manufacturing step, dewaxing step and baking step, shell manufacturing step is covered with sand mortar to the outer surface of first connecting body, screw wax piece of first connecting body is removed in dewaxing step, obtains second connecting body;Casting forming part has pouring step and shell vibration step, pouring step is injected into metal liquid to the inner cavity formed by shell and support frame, obtains third connecting body after cooling, shell vibration step is broken to the shell of third connecting body, obtains semi-finished product screw;Post-processing part, post-processing treatment to semi-finished product screw, obtains finished product screw.The application can reduce the phenomenon and quantity of screw bending deformation, reduce the difficulty of screw deformation finishing, thereby, improve yield.

Description

Technical Field

[0001] This invention relates to the technical field of screw manufacturing, and particularly to an investment casting process for screws. Background Technology

[0002] In the production of screws, screws can be manufactured by bar milling or by investment casting. The investment casting process for screws includes processes such as wax pressing, shell making, dewaxing, baking, pouring, and shell vibration. After a series of post-processing steps, the desired screw product is obtained.

[0003] However, in the wax pressing process, wax liquid is injected into the mold using a wax injection machine. After the wax liquid in the mold cools, a wax model is obtained. During the cooling process, the wax model will shrink, bend, and deform. Consequently, the finished screw produced later will also be bent and deformed. Moreover, the length of the screw is about 1 meter, making it more prone to bending during the manufacturing process. Therefore, a shaping process needs to be added in the post-processing stage, which increases the manufacturing cost of the screw. At the same time, it is difficult to adjust the bending deformation of the screw, resulting in a low yield rate of the screw. Summary of the Invention

[0004] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention proposes an investment casting process for screws that can reduce the phenomenon and amount of bending deformation in screws, reduce the difficulty of screw deformation repair, and thus improve the yield rate.

[0005] According to a first aspect of the present invention, a screw investment casting process includes: a wax pattern forming section having a screw wax pattern making step, wherein the screw wax pattern making step uses a first wax injection mold and a support frame, the support frame is placed in the cavity of the first wax injection mold and wax liquid is injected to obtain a first connector, the first connector including the support frame and a screw wax part enclosing the support frame; a mold shell forming section having a shell forming step, a dewaxing step and a baking step, wherein the shell forming step covers the outer surface of the first connector with slurry, and the dewaxing step removes the screw wax part of the first connector to obtain a second connector, the second connector including a mold shell and the support frame disposed in the inner cavity of the mold shell; a casting forming section having a pouring step and a shell vibration step, wherein the pouring step injects molten metal into the inner cavity formed by the mold shell and the support frame, and obtains a third connector after cooling, and the shell vibration step breaks the mold shell of the third connector to obtain a semi-finished screw; and a post-processing section for post-processing the semi-finished screw to obtain a finished screw.

[0006] According to some embodiments of the present invention, the support frame includes a rod portion and an overlapping portion disposed at one end of the rod portion, the rod portion extending axially along the screw wax element, and the overlapping portion being used to overlap the mold shell to prevent the support frame from detaching from the mold shell.

[0007] According to some embodiments of the present invention, the wax model forming part includes a collar wax model making step, wherein the collar wax model making step uses a second wax injection mold to inject liquid wax into the cavity of the second wax injection mold to obtain a collar wax part, wherein the collar wax part is fitted onto the end of the rod away from the overlapping part.

[0008] According to some embodiments of the present invention, the screw wax part includes a spiral portion and a gate portion connected to the spiral portion, and the overlapping portion is disposed on the gate portion.

[0009] According to some embodiments of the present invention, the casting step uses a casting furnace and a bracket, with the overlapping portion overlapping on the bracket, so that the second connector is erected, and the casting furnace pours molten metal into the inner cavity of the second connector.

[0010] According to some embodiments of the present invention, the shell-making step includes a zircon sand adhesion section, a fine sand adhesion section, and a coarse sand adhesion section. In the zircon sand adhesion section, the first connector is adhered to zircon sand once. In the fine sand adhesion section, the first connector is adhered to fine sand twice. In the coarse sand adhesion section, the first connector is adhered to coarse sand three times.

[0011] According to some embodiments of the present invention, after the first connector is adhered to coarse sand twice in the coarse sand adhesion section, a metal wire is wrapped around the outer surface of the first connector, and the first connector is then adhered to coarse sand once more to reinforce the mold shell.

[0012] According to some embodiments of the present invention, the calcination step uses a sintering furnace, the second connector is placed horizontally on a material rack, and the material rack is moved into the sintering furnace for calcination at a sintering temperature of 1120°C.

[0013] According to some embodiments of the present invention, the shell-vibrating step uses a shell-vibrating machine, in which the third connector is placed horizontally on a workbench, and the shell-vibrating machine is used to break the mold shell.

[0014] According to some embodiments of the present invention, the post-processing section includes a polishing step, a cutting step, a grinding step, an acid pickling step, and a quality inspection step.

[0015] The investment casting process for a screw according to an embodiment of the present invention has at least the following beneficial effects:

[0016] 1. The present invention, through the setting of a screw wax mold making step, places the support frame in the cavity of the first wax injection mold, so that the support frame is located at the center of the cavity of the first wax injection mold, and uses a wax injection machine to inject wax into the cavity of the first wax injection mold. After the wax cools, a first connection body is obtained formed by the screw wax part and the support frame. The screw wax part is wrapped in the support frame, and the support frame can support the screw wax part and improve the bending strength of the screw wax part.

[0017] 2. By setting up a support frame, the present invention occupies part of the cavity space of the first wax injection mold. The support frame replaces the wax as the axis of the screw wax part, reducing the amount of wax used and injected. Therefore, it greatly reduces the deformation caused by the cooling and shrinkage of the screw wax part, so that the size of the screw wax part remains stable.

[0018] 3. This invention incorporates a shell-making step, a dewaxing step, and a firing step. In the shell-making step, the first connector is placed in a slurry tank, and mortar adheres to its surface. The first connector is then suspended on a frame, and after air drying, the mortar solidifies within it. Therefore, in the shell-making step, the support frame can support and suspend the screw wax part, eliminating the need for additional hooks on the screw wax part. Next, in the dewaxing step, the screw wax part melts to form liquid wax, which flows out from the first connector, obtaining a mold shell. The mold shell and the support frame form a second connector, with the support frame located within the cavity of the mold shell.

[0019] 4. By setting a pouring step, the present invention pours molten metal into the inner cavity of the mold shell. After the molten metal cools, it forms a screw. During this process, the support frame is solid and the deformation is small. The support frame can improve the bending strength of the entire screw and reduce the bending deformation of the screw during cooling and forming.

[0020] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0021] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0022] Figure 1 This is a flowchart of an investment casting process for a screw according to an embodiment of the present invention;

[0023] Figure 2 This is a schematic diagram of the lower mold structure of the first wax injection mold in a screw investment casting process according to an embodiment of the present invention;

[0024] Figure 3 for Figure 2 A schematic diagram of the upper mold structure of the first wax injection mold in a screw investment casting process is shown.

[0025] Figure 4 for Figure 2 A schematic diagram of the structure of a screw wax part in an investment casting process is shown;

[0026] Figure 5 for Figure 2 The diagram shows a structural schematic of a support frame for a screw in an investment casting process.

[0027] Reference numerals: 100-First wax injection mold, 110-Upper mold, 120-Lower mold, 130-Support frame, 140-Rod part, 150-Overlapping part, 160-Screw wax part, 170-Spiral part, 180-Gate part, 190-First positioning groove, 200-Second positioning groove, 210-Cavity, 220-Ring wax part, 230-Insert. Detailed Implementation

[0028] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0029] In the description of this invention, it should be understood that the orientation descriptions, such as up, down, front, back, left, right, etc., are based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0030] In the description of this invention, "several" means one or more, "more than" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0031] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0032] The following describes a screw investment casting process according to an embodiment of the present invention with reference to the accompanying drawings.

[0033] Reference Figure 1 An investment casting process for a screw according to an embodiment of the present invention includes a wax pattern forming part, a mold shell forming part, a casting forming part, and a post-processing part.

[0034] The wax model forming part includes a screw wax model making step. The screw wax model making step uses a first wax injection mold 100 and a support frame 130. The support frame 130 is placed in the cavity 210 of the first wax injection mold 100 and wax liquid is injected to obtain a first connector. The first connector includes the support frame 130 and a screw wax part 160 that wraps the support frame 130.

[0035] It should be noted that the support frame 130 can be made of stainless steel.

[0036] Specifically, refer to Figure 4 and 5 The support frame 130 includes a rod portion 140 and an overlapping portion 150 disposed at one end of the rod portion 140. The rod portion 140 extends axially along the screw wax part 160, and the overlapping portion 150 is used to overlap the mold shell.

[0037] Therefore, the diameter of the rod 140 is 16mm and its length is greater than that of the screw wax part 160. The rod 140 can be coaxially arranged with the screw wax part 160, so that the rod 140 can support the screw wax part 160, improve the bending strength of the screw wax part 160, and reduce the problem of bending deformation of the screw wax part 160.

[0038] Meanwhile, in the subsequent dewaxing step, the overlapping part 150 can overlap with the mold shell, which can prevent the support frame 130 from detaching from the mold shell.

[0039] In the structure of the first wax injection mold 100, refer to Figure 2 and Figure 3 The first wax injection mold includes an upper mold 110 and a lower mold 120, and a cavity 210 is provided between the mating surfaces of the upper mold 110 and the lower mold 120.

[0040] Furthermore, a first positioning groove 190 and a second positioning groove 200 are formed between the mating surfaces of the upper mold 110 and the lower mold 120. The first positioning groove 190 and the second positioning groove 200 are located at the two ends of the cavity 210, respectively. The end of the rod portion 140 away from the overlapping portion 150 can overlap with the first positioning groove 190, and the overlapping portion 150 can overlap with the second positioning groove 200.

[0041] In addition, the lower mold 120 is provided with a number of inserts 230, which are distributed on both sides of the cavity 210, and the cavity 210 is formed between the upper mold 110, the lower mold 120 and the inserts 230.

[0042] By setting the insert 230, which is separate from the lower mold 120, the manufacturing difficulty and cost of the lower mold are reduced.

[0043] Specifically, refer to Figure 3 The screw wax part 160 includes a spiral part 170 and a gate part 180 connected to the spiral part 170. An overlapping part 150 is provided on the gate part 180. Therefore, the overlapping part 150 can improve the strength of the gate part 180. At the same time, the overlapping part 150 can overlap the mold shell, which can prevent the support frame 130 from detaching from the mold shell.

[0044] For example, the diameter of the spiral part 170 is 97 mm and the length is 824 mm.

[0045] In some embodiments of the present invention, reference is made to... Figure 4 The wax model forming part includes a ring wax model making step. The ring wax model making step uses a second wax injection mold to inject wax liquid into the cavity 210 in the second wax injection mold to obtain a ring wax part 220. The ring wax part 220 is fitted onto the end of the rod 140 away from the overlapping part 150.

[0046] For example, the outer diameter of the collar wax piece 220 is 20mm and the inner diameter is 16mm. The collar wax piece 220 can be fitted onto the end of the rod 140 of the support frame 130.

[0047] For the production steps of the collar wax model, use a wax injection machine to inject wax liquid into the second wax injection mold, prepare the collar wax part 220 in advance, and manually put the collar wax part 220 onto the end of the rod 140 away from the overlapping part 150.

[0048] If the ring wax part 220 does not wrap the end of the rod 140, and the end of the rod 140 is directly covered by mortar, then in the subsequent firing step, there will be no gap between the rod 140 of the support frame 130 and the mold shell. At the same time, the support frame 130 is metal and the mold shell is non-metal. Due to the difference in the coefficient of thermal expansion and contraction between metal and non-metal, the connection between the end of the rod 140 of the support frame 130 and the mold shell will break, thereby destroying the mold shell.

[0049] Therefore, by having the ring wax 220 wrap around the end of the rod 140, the end of the rod 140 can be prevented from being covered by mortar in the subsequent shell-making step. This ensures that there is a gap between the end of the rod 140 and the mold shell after the dewaxing step, and prevents the mold shell from being torn by the end of the rod 140 in the subsequent baking step.

[0050] The mold shell forming part includes a shell making step, a dewaxing step, and a baking step. The shell making step covers the outer surface of the first connector with mortar. The dewaxing step removes the screw wax part 160 of the first connector to obtain the second connector. The second connector includes a mold shell and a support frame 130 disposed in the inner cavity of the mold shell.

[0051] In some embodiments of the present invention, the shell-making step includes a zircon sand adhesion section, a fine sand adhesion section, and a coarse sand adhesion section. In the zircon sand adhesion section, the first connector is adhered to zircon sand once; in the fine sand adhesion section, the first connector is adhered to fine sand twice; and in the coarse sand adhesion section, the first connector is adhered to coarse sand three times. Thus, the desired mold shell is obtained, preparing for the subsequent casting step.

[0052] Specifically, the operator places the first connector into the zircon sand slurry bucket to adhere zircon sand once, removes it and hangs it on the material rack. The material rack is then moved to the fine sand adhesion section, and the first connector is placed into the fine sand bucket to adhere fine sand twice. After removing it, it is hung on the material rack, and the material rack is moved to the coarse sand adhesion section. Finally, the first connector is placed into the coarse sand bucket to adhere coarse sand three times to obtain the second connector.

[0053] It should be noted that after the first connector is coated with coarse sand twice in the coarse sand adhesion section, a metal wire is wrapped around the outer surface of the first connector, and the first connector is coated with coarse sand once more to reinforce the mold shell.

[0054] Specifically, the end of the metal wire can be wrapped around the overlap first, and then the metal wire can be wrapped along the surface of the first connector.

[0055] In addition, after the shell-making step is completed, the second connector is placed in a drying room and dried with a fan to solidify the mold shell.

[0056] In the dewaxing step, the second connector is placed in a steam generator, which heats the second connector. The screw wax component 160 and the collar wax component 220 in the second connector melt, and the wax flows out from the gate 180 to obtain the third connector.

[0057] It should be noted that at this time, there is a gap of about 3mm on one side between the rod 140 of the support frame 130 and the mold shell, which ensures that the rod 140 of the support frame 130 will not tear the mold shell during the baking step.

[0058] In some embodiments of the present invention, the calcination step uses a sintering furnace. The second connector is placed horizontally on a material rack, and the material rack is moved into the sintering furnace for calcination at a temperature of 1120°C. This ensures that the mold shell has sufficient strength while preventing the mold shell from cracking due to excessive temperature.

[0059] The casting process includes a pouring step and a shell-vibrating step. In the pouring step, molten metal is injected into the cavity formed by the mold shell and the support frame 130. After cooling, a third connector is obtained. In the shell-vibrating step, the mold shell of the third connector is broken to obtain a semi-finished screw.

[0060] In some embodiments of the present invention, the casting step uses a casting furnace and a bracket, with the overlapping portion 150 overlapping on the bracket, so that the second connector is set up vertically. The casting furnace pours molten metal into the inner cavity of the second connector. Therefore, the bracket directly supports the overlapping portion 150 without contacting the mold shell, which facilitates the vertical setting of the second connector, allowing the molten metal to fall naturally into the inner cavity of the second connector and wait for the molten metal to solidify.

[0061] In some embodiments of the present invention, the shell-vibrating step uses a shell-vibrating machine, in which the third connector is placed horizontally on a workbench and the shell-vibrating machine is used to break the mold shell.

[0062] Of course, a hammer can also be used to manually break the mold shell to obtain a semi-finished screw, depending on actual needs.

[0063] The post-processing section involves processing the semi-finished screw to obtain the finished screw.

[0064] In some embodiments of the present invention, the post-processing part includes a polishing step, a cutting step, a grinding step, an acid pickling step, and a quality inspection step.

[0065] Therefore, the lifting and polishing step uses a lifting and polishing machine. The semi-finished screw is placed into the lifting and polishing machine, which cleans away the mold shell remaining on the outer surface of the semi-finished screw.

[0066] Next, the cutting step uses a cutting machine to remove the gate portion 180 of the semi-finished screw.

[0067] In addition, a grinding machine is used in the grinding step to smooth the cut part of the semi-finished screw.

[0068] Furthermore, the pickling step uses a pickling tank, where the semi-finished screw is placed for pickling.

[0069] Finally, the quality inspection step checks the appearance and dimensions of the screw to confirm whether it is qualified.

[0070] Therefore, this embodiment has the following effects:

[0071] 1. The present invention, through the setting of a screw wax mold making step, places the support frame 130 in the cavity 210 of the first wax injection mold 100, so that the support frame 130 is located at the center of the cavity 210 of the first wax injection mold 100. The wax liquid is injected into the cavity 210 of the first wax injection mold 100 using a wax injection machine. After the wax liquid cools, a first connecting body is obtained formed by the screw wax part 160 and the support frame 130. The screw wax part 160 is wrapped in the support frame 130, and the support frame 130 can support the screw wax part 160 and improve the bending strength of the screw wax part 160.

[0072] 2. By setting up a support frame 130, the support frame 130 occupies part of the cavity 210 of the first wax injection mold 100. The support frame 130 replaces the wax as the axis of the screw wax part 160, reducing the amount of wax used and the amount injected. Therefore, it greatly reduces the deformation caused by the cooling and shrinkage of the screw wax part 160, so that the size of the screw wax part 160 remains stable.

[0073] 3. This invention incorporates a shell-making step, a dewaxing step, and a firing step. In the shell-making step, the first connector is placed in a slurry tank, and mortar adheres to its surface. The first connector is then suspended on a frame, and after air drying, the mortar solidifies on the first connector. Therefore, in the shell-making step, the support frame 130 can support and suspend the screw wax part 160, eliminating the need for additional hooks on the screw wax part 160. Next, in the dewaxing step, the screw wax part 160 melts to form liquid wax, which flows out from the first connector to obtain a mold shell. The mold shell and the support frame 130 form a second connector, with the support frame 130 located within the cavity of the mold shell.

[0074] 4. By setting a pouring step, the present invention pours molten metal into the inner cavity of the mold shell. After the molten metal cools, it forms a screw. During this process, the support frame 130 is solid and the deformation is small. The support frame 130 can improve the bending strength of the entire screw and reduce the bending deformation of the screw during cooling and forming.

[0075] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0076] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A screw investment casting process, characterized in that, include: The wax model forming part includes a screw wax model making step, which uses a first wax injection mold (100) and a support frame (130). The support frame (130) is placed in the cavity (210) of the first wax injection mold (100) and wax liquid is injected to obtain a first connector. The first connector includes the support frame (130) and a screw wax part (160) that wraps the support frame (130). The mold shell forming part has a shell making step, a dewaxing step and a baking step. The shell making step covers the outer surface of the first connector with mortar. The dewaxing step removes the screw wax part (160) of the first connector to obtain a second connector. The second connector includes a mold shell and a support frame (130) disposed in the inner cavity of the mold shell. The support frame (130) includes a rod (140) and an overlapping portion (150) disposed at one end of the rod (140). The rod (140) extends axially along the screw wax part (160), and the overlapping portion (150) is used to overlap the mold shell to prevent the support frame (130) from detaching from the mold shell. The shell-making step includes a zircon sand adhesion section, a fine sand adhesion section, and a coarse sand adhesion section. In the zircon sand adhesion section, the first connector is adhered to zircon sand once. In the fine sand adhesion section, the first connector is adhered to fine sand twice. In the coarse sand adhesion section, the first connector is adhered to coarse sand three times. After the first connector is coated with coarse sand twice in the coarse sand adhesion section, a metal wire is wrapped around the outer surface of the first connector, and the first connector is coated with coarse sand once more to reinforce the mold shell. The end of the metal wire is wrapped around the overlap, and then the metal wire is wrapped along the surface of the first connector. The casting part has a pouring step and a shell vibration step. The pouring step injects molten metal into the cavity formed by the mold shell and the support frame (130), and obtains a third connector after cooling. The shell vibration step crushes the mold shell of the third connector to obtain a semi-finished screw. The casting step uses a casting furnace and a bracket to overlap the joint (150) on the bracket, so that the second connector is erected. The casting furnace pours molten metal into the inner cavity of the second connector. In the post-processing section, the semi-finished screw is processed to obtain the finished screw.

2. The investment casting process for a screw according to claim 1, characterized in that, The wax model forming part has a ring wax model making step. The ring wax model making step uses a second wax injection mold to inject wax liquid into the cavity (210) in the second wax injection mold to obtain a ring wax part (220). The ring wax part (220) is fitted onto the end of the rod (140) away from the overlapping part (150).

3. The investment casting process for a screw according to claim 1, characterized in that, The screw wax part (160) includes a spiral part (170) and a gate part (180) connected to the spiral part (170), and the overlapping part (150) is disposed on the gate part (180).

4. The investment casting process for a screw according to claim 1, characterized in that, The roasting step uses a sintering furnace. The second connector is placed horizontally on a material rack, and the material rack is moved into the sintering furnace for roasting at a temperature of 1120°C.

5. The investment casting process for a screw according to claim 1, characterized in that, The shell-vibrating step uses a shell-vibrating machine to place the third connector horizontally on a workbench. The shell-vibrating machine is used to break the mold shell.

6. The investment casting process for a screw according to claim 1, characterized in that, The post-processing section includes a polishing step, a cutting step, a grinding step, a pickling step, and a quality inspection step.

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