Device for improving shell expansion during baking of photosensitive resin investment mold for precision casting

Abstract

Device for improving the shell expansion during baking of photosensitive resin investment mold for precision casting. The investment mold is provided with a first air extraction hole communicating with the internal hollow structure. The device includes a container, a sealing seat, an air extraction pipe, a negative pressure device, a control system and a driving mechanism. The container is filled with a plugging agent. The sealing seat is hermetically connected to the container, and the container is supported and fixed on the investment mold through the sealing seat. The air extraction pipe passes through the container and the sealing seat from top to bottom. The air extraction pipe is in sealed cooperation with the container. A second air extraction hole is provided on the wall of the air extraction pipe, and the second air extraction hole communicates with the inner cavity of the container. The driving mechanism is used to control the air extraction pipe to move only up and down. The control system is used to heat the plugging agent into a molten state. The investment mold and the container are evacuated through the negative pressure device, so that the cavity of the investment mold and the inner cavity of the container are in a negative pressure state. The first air extraction hole is blocked by the plugging agent in a molten state in the container passing through the sealing seat and finally solidifying. By utilizing the pressure difference between the inside and the outside of the investment mold, the problem of shell expansion during the baking process is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of investment precision casting, and particularly relates to a device for improving the roasting shell expansion of a photosensitive resin investment mold for precision casting. Background Art

[0002] With the development of 3D printing technology, 3D printed photosensitive resin investment molds prepared based on the principle of photocuring are increasingly widely used as models for casting precision casting. The photocured 3D printed photosensitive resin investment mold has the advantages of low surface roughness and high dimensional accuracy, but also has the disadvantage of a large coefficient of thermal expansion. During the high-temperature roasting process of the shell, due to expansion, a large pressure is exerted on the shell, resulting in the shell cracking and scrapping. Therefore, the industry has evacuated the internal structure of the photosensitive resin investment mold. While reducing the amount of photosensitive resin used, the wall of the photosensitive resin investment mold can be recessed inward when heated to reduce the risk of shell cracking; however, the air in the internal hollow structure of the photosensitive resin investment mold is in a closed state. When heated, the air will expand in volume, which will lead to the problem of shell expansion during the roasting process of the shell.

[0003] In view of this, the inventor of the present invention has conducted in-depth research on the above-mentioned defects in the prior art, and thus this case has arisen. Summary of the Invention

[0004] The purpose of the present invention is to provide a device for improving the roasting shell expansion of a photosensitive resin investment mold for precision casting. By using the pressure difference between the inside and outside of the investment mold, the investment mold shrinks inward during the roasting process of the shell, so that no expansion pressure is exerted on the shell wall, and fundamentally solves the problem of shell expansion during the roasting process of the photosensitive resin investment mold.

[0005] To achieve the above object, a device for improving the roasting expansion of a photosensitive resin investment casting mold has an investment casting mold with a cavity structure, and a first air extraction hole communicating with the cavity is provided on the wall of the investment casting mold. The device includes a container, a sealing seat, an air extraction pipe, a negative pressure device, a control system, and a driving mechanism; the inner cavity of the container is hollow, and a first through hole and a second through hole are respectively provided on the top wall and the bottom wall of the container, and the inner cavity of the container can be used to hold a plugging agent; the sealing seat is hermetically connected to the second through hole of the container, and through the sealing seat, the container is supported and fixed on the investment casting mold. An installation hole is provided on the sealing seat, and the installation hole, the second through hole, and the first air extraction hole are butt-jointed and communicated; the air extraction pipe sequentially passes through the first through hole, the second through hole, and the installation hole from top to bottom and is at least partially arranged in the inner cavity of the container. A second air extraction hole is provided on the wall of the air extraction pipe, and the second air extraction hole is communicated with the inner cavity of the container. The outer wall of the air extraction pipe is hermetically matched with the inner wall of the container by adding a plurality of sealing rings. The air extraction pipe is connected to the inside of the negative pressure device, and the air extraction pipe can only move up and down in the inner cavity of the container under the drive of the driving mechanism; the control system is used to heat the plugging agent into a molten state; when the air extraction pipe moves downward and passes through the first air extraction hole of the investment casting mold, at this time, the investment casting mold and the container are simultaneously evacuated through the negative pressure device, so that the inner cavity of the investment casting mold and the inner cavity of the container are in a negative pressure state; when the air extraction pipe moves upward until the molten plugging agent can sequentially pass through the second through hole of the container, the installation hole of the sealing seat, and finally the solidified plugging agent plugs the first air extraction hole of the investment casting mold.

[0006] With the above design, a closed space is formed among the sealing seat, the container, and the investment casting mold. During air extraction, the air extraction pipe moves downward under the drive of the driving mechanism until it passes through the first air extraction hole of the investment casting mold, and the second air extraction hole on the air extraction pipe is communicated with the inner cavity of the container. Thus, the investment casting mold and the container are simultaneously evacuated through the negative pressure device, so that the inner cavity of the investment casting mold and the inner cavity of the container are in a negative pressure state; after air extraction, the rigid pipe moves upward under the drive of the driving mechanism until the molten plugging agent can sequentially pass through the second through hole, the installation hole, and finally the solidified plugging agent plugs the first air extraction hole of the investment casting mold. The device of the present invention evacuates the investment casting mold and plugs the first air extraction hole with a plugging agent, so that the air pressure inside the investment casting mold is less than the external air pressure. During the shell roasting stage, when the investment casting mold is heated and softened, the investment casting mold contracts inward due to the air pressure difference, thereby eliminating the expansion pressure of the investment casting mold on the shell and fundamentally solving the problem of shell expansion of the photosensitive resin investment casting mold during the roasting process.

[0007] Furthermore, a tapered portion is provided at the bottom of the air extraction pipe, and its diameter gradually decreases from top to bottom.

[0008] With such a setting, if the rigid pipe is not provided with a tapered portion, the rigid pipe needs to move upward to disengage from the second through hole before the molten sealant can pass through, thereby sealing the first air extraction hole. However, with the provision of the tapered portion, the rigid pipe only needs to move upward until a gap for the molten sealant to pass through is formed between the tapered portion and the second through hole, greatly reducing the upward travel of the rigid pipe.

[0009] Furthermore, the first air extraction hole is provided as a tapered hole adapted to the tapered portion to better position the sealant and the rigid pipe. Brief Description of the Drawings

[0010] Specific descriptions given as non-limiting examples better explain what the present invention includes and how it can be implemented. In addition, this description refers to the accompanying drawings, in which:

[0011] Figure 1 is an exploded view of the device of the present invention;

[0012] Figure 2 is a schematic diagram when the device of the present invention is extracting air;

[0013] Figure 3 is a schematic diagram after the device of the present invention extracts air. Detailed Description of the Invention

[0014] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0015] In the description of the present invention, it should be understood that the orientation or positional relationships indicated by the terms "upper", "lower", "top", "bottom", "inner", "outer", etc. are based on the orientation or positional relationships shown in the accompanying drawings. These are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present invention; in the description of the present invention, "negative pressure equipment" often selects devices such as vacuum pumps and vacuum chambers.

[0016] In the claims and the specification, unless otherwise defined, the terms "first", "second", etc. are all used to distinguish different objects and are not used to describe a specific order.

[0017] Please refer to Figures 1 to 3, a device for improving the roasting expansion of the photosensitive resin investment casting mold 100. The investment casting mold 100 has a cavity 101 structure, and a first air extraction hole 102 communicating with the cavity 101 is provided on the wall of the investment casting mold 100. The device includes a container 1, a sealing seat 2, an air extraction pipe 3, a negative pressure device, a control system 4 and a driving mechanism 5; the inner cavity of the container 1 is hollow, and a first through hole 11 and a second through hole 12 are respectively provided on its top wall and bottom wall. The container 1 is also provided with an inlet 13, and a detachable sealing cover 14 is provided at the inlet 13. An appropriate amount of sealing agent can be injected from the inlet 13 of the container 1 and fall to the bottom of the container 1, and then the sealing cover 14 can be covered. Most of the sealing agent is wax. Please refer to Figure 1 , the control system 4 includes a heating module 41, a coil 43 and a constant temperature module 42. The coil 43 is placed at the sealing agent in the inner cavity of the container 1. The coil 43 is heated by the heating module 41 to make the sealing agent in a molten state. The constant temperature module 42 is used to keep the molten sealing agent at a constant temperature in the container 1.

[0018] The sealing seat 2 is hermetically connected to the second through hole 12 of the container 1. Through the sealing seat 2, the container 1 is supported and fixed on the investment casting mold 100. An installation hole 21 is provided on the sealing seat 2. The installation hole 21, the second through hole 12 and the first air extraction hole 102 are docked and communicated. In this example, the sealing seat 2 is a suction cup. Using the working principle of the suction cup, the container 1 is supported and fixed on the investment casting mold 100.

[0019] The air extraction pipe 3 includes a flexible pipe 33 and a rigid pipe 34 from top to bottom. The flexible pipe 33 and the rigid pipe 34 are connected by a quick connector 7, so that the movement between the flexible pipe 33 and the rigid pipe 34 is not restricted by each other; specifically, the quick connector 7 is provided with a through shaft hole. One end of the flexible pipe 33 is in interference connection with the shaft hole of the quick connector 7, and the other end is connected to the negative pressure device. One end of the rigid pipe 34 is movably connected to the shaft hole of the quick connector 7, and the other end of the rigid pipe 34 sequentially passes through the first through hole 11, the second through hole 12 and the installation hole 21 from top to bottom and is at least partially arranged in the inner cavity of the container 1. A second air extraction hole 31 is provided on the wall of the rigid pipe 34. The second air extraction hole 31 communicates with the inner cavity of the container 1. The outer wall of the rigid pipe 34 is hermetically matched with the inner wall of the first through hole 11 of the container 1 by adding a plurality of sealing rings 6. Please refer to Figure 1 , the driving mechanism 5 includes a micro motor 51 and a gear 52. The gear 52 is driven to rotate by the micro motor 51. An engaging portion 35 that cooperates with the tooth groove of the gear 52 is provided on the outer wall of the rigid pipe 34. By rotating the gear 52, the rigid pipe 34 is driven to move up and down, so that the rigid pipe 34 moves up and down under the drive of the driving mechanism 5, while the flexible pipe 33 remains stationary.

[0020] Preferably, a protective cover 8 is provided around the control system 4 and the driving mechanism 5 .

[0021] The specific working principle of the present invention is:

[0022] See also Figure 2 First, the rigid tube 34 moves downward under the drive mechanism 5 until it passes through the first exhaust hole 102 of the investment mold 100. At this time, the investment mold 100 and the container 1 are exhausted by the negative pressure device, so that the cavity 101 of the investment mold 100 and the inner cavity of the container 1 are in a negative pressure state, and the plugging agent in the container 1 is heated to a molten state through the control system 4. Of course, it should be noted that before exhausting, the plugging agent in the container 1 can also be heated to a molten state; then, please refer to Figure 3 The rigid tube 34 moves upward under the drive of the driving mechanism 5 until the molten plugging agent can pass through the second through hole 12 and the mounting hole 21 in sequence, and the finally solidified plugging agent blocks the first exhaust hole 102 of the investment mold 100; finally, the investment mold 100 is removed from the device, and the negative pressure operation of the investment mold 100 is completed.

[0023] Preferably, the bottom of the rigid tube 34 is provided with a tapered portion 32, and its diameter gradually decreases from top to bottom. If the rigid tube 34 is not provided with the tapered portion 32, the rigid tube 34 needs to move upward to be separated from the second through hole 12 to allow the molten plugging agent to pass through, thereby blocking the first air extraction hole 102. The provision of the tapered portion 32 allows the rigid tube 34 to move upward to form a gap between the tapered portion 32 and the second through hole 12 for the molten plugging agent to pass through, which greatly reduces the upward travel of the rigid tube 34. More preferably, the first air extraction hole 102 is provided as a tapered hole adapted to the tapered portion 32, so as to better position the plugging agent and the rigid tube 34.

[0024] The beneficial effects of the present invention are as follows: the present invention performs a vacuum treatment on the wrought pattern 100, and seals the first vacuum hole 102 with a sealing agent, so that the air pressure inside the wrought pattern 100 is lower than the external air pressure. During the shell firing stage, when the wrought pattern 100 is softened by heat, the air pressure difference is used to cause the wrought pattern 100 to shrink inward, thereby eliminating the expansion pressure of the wrought pattern 100 on the shell, fundamentally solving the shell expansion problem of the photosensitive resin wrought pattern 100 during the firing process.

[0025] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. Device for improving the roasting shell expansion of photosensitive resin investment casting patterns. The investment casting pattern (100) has a cavity (101) structure, and a first air extraction hole (102) communicating with the cavity (101) is provided on the wall of the investment casting pattern (100), characterized in that: The device includes a container (1), a sealing seat (2), an air extraction pipe (3), a negative pressure device (9), a control system (4) and a driving mechanism (5); the inner cavity of the container (1) is hollow, and its top wall and bottom wall are respectively provided with a first through hole (11) and a second through hole (12), and the inner cavity of the container (1) can be used to contain a plugging agent; the sealing seat (2) is hermetically connected to the second through hole (12) of the container (1), and through the sealing seat (2), the container (1) is supported and fixed on the investment casting mold (100), the sealing seat (2) is provided with a mounting hole (21), and the mounting hole (21), the second through hole (12) and the first air extraction hole (102) are docked and communicated; the air extraction pipe (3) sequentially passes through the first through hole (11), the second through hole (12) and the mounting hole (21) from top to bottom, and is at least partially arranged in the inner cavity of the container (1), the wall of the air extraction pipe (3) is provided with a second air extraction hole (31), and the second air extraction hole (31) is communicated with the inner cavity of the container (1), the outer wall of the air extraction pipe (3) is hermetically matched with the inner wall of the container (1) by adding a plurality of sealing rings (6), the air extraction pipe (3) is communicated with the inside of the negative pressure device (9), and the air extraction pipe (3) can only move up and down in the inner cavity of the container (1) driven by the driving mechanism (5); the control system (4) is used to heat the plugging agent into a molten state; when the air extraction pipe (3) moves downward and passes through the first air extraction hole (102) of the investment casting mold (100), at this time, the investment casting mold (100) and the container (1) are simultaneously evacuated by the negative pressure device (9), so that the cavity (101) of the investment casting mold (100) and the inner cavity of the container (1) are in a negative pressure state; when the air extraction pipe (3) moves upward to the molten plugging agent, it can sequentially pass through the second through hole (12) of the container (1), the mounting hole (21) of the sealing seat (2), and finally the solidified plugging agent blocks the first air extraction hole (102) of the investment casting mold (100).

2. The device for improving the baking expansion of the photosensitive resin investment mold for precision casting according to claim 1, wherein: The bottom of the air extraction pipe (3) is provided with a tapered portion (32), and its diameter gradually decreases from top to bottom.

3. The device for improving the roasting shell expansion of the photosensitive resin investment mold for precision casting according to claim 2, characterized in that: The first air extraction hole (102) is arranged as a tapered hole adapted to the tapered portion (32).

4. The device for improving the baking expansion of the photosensitive resin investment casting mold as described in claim 1, wherein: The sealing seat (2) is a suction cup, and by using the working principle of the suction cup, the container (1) is supported and fixed on the investment casting mold (100).

5. The device for improving the roasting expansion of the photosensitive resin investment mold for precision casting according to claim 1, characterized in that: The driving mechanism (5) includes a micro motor (51) and a gear (52), the gear (52) is driven to rotate by the micro motor (51), the outer wall of the air extraction pipe (3) is provided with an engaging portion (35) that cooperates with the gear (52), and the gear (52) rotates to drive the air extraction pipe (3) to move up and down.

6. The device for improving the baking expansion of the photosensitive resin investment casting mold according to claim 1, characterized in that: The control system (4) includes a heating module (41) and a coil (42), the coil (42) is placed at the plugging agent in the inner cavity of the container (1), and the coil (42) is heated by the heating module (41) to make the plugging agent in a molten state.

7. The device for improving the roasting shell expansion of the photosensitive resin investment casting pattern according to claim 6, characterized in that: The control system (4) further includes a constant temperature module (43), and through the constant temperature module (43), the molten plugging agent is kept at a constant temperature in the container (1).

8. The device for improving the roasting expansion of the photosensitive resin investment casting mold as described in claim 1, characterized in that: The exhaust pipe (3) includes a flexible pipe (33) and a rigid pipe (34) from top to bottom. The flexible pipe (33) and the rigid pipe (34) are connected by a quick connector (7). When the rigid pipe (34) moves up and down driven by the driving mechanism (5), the flexible pipe (33) remains stationary.

9. The device for improving the baking expansion of the photosensitive resin investment mold for precision casting according to claim 1, wherein: The container (1) is further provided with an inlet (13), and a detachable sealing cover (14) is provided at the inlet (13).

10. The device for improving the roasting expansion of the photosensitive resin investment casting mold as described in claim 1, characterized in that: The plugging agent is wax.

11. The device for improving the roasting shell expansion of the photosensitive resin investment casting pattern according to claim 1, wherein: A protective cover (8) is additionally provided around the control system (4) and the driving mechanism (5).

Images