Composite production process for exhaust pipe of engine of unmanned aerial vehicle

Abstract

The invention discloses a composite production process for an unmanned aerial vehicle engine exhaust pipe, and belongs to the field of exhaust pipes. Comprising the following steps that S1, a die is designed and manufactured, specifically, a die-casting die comprising a multi-point sequential filling runner system, an exhaust groove system with the depth being 0.10-0.15 mm, a combined cooling water channel and heating oil channel system and a multi-direction core pulling mechanism is manufactured; and S2, smelting and refining are conducted, specifically, the ADC12 aluminum alloy is placed in a smelting furnace at the temperature of 680 + / -20 DEG C to be smelted and subjected to heat preservation, and then rotary degassing refining is conducted. And in addition, combined production of the die-casting process and the welding process is combined, the machining and production steps are further simplified, the machining and production time is further shortened, the production efficiency is improved, and meanwhile the labor cost is reduced. The production steps are reduced, the overall production efficiency is obviously improved, and the production cost is obviously reduced. The method is particularly suitable for large-scale and standardized production of the exhaust pipe of the unmanned aerial vehicle engine, meanwhile, compared with a welding process, too many welding spots are avoided, and the overall strength and stability are improved.

Description

Technical Field

[0001] This application relates to the field of exhaust pipes, and more specifically, to a composite manufacturing process for exhaust pipes of drone engines. Background Technology

[0002] Most drone engines currently on the market are reciprocating piston engines. The exhaust pipe, as a crucial component, serves to reduce engine noise and guide exhaust gases to the outside of the drone. The design, size, and layout of the exhaust pipe must be coordinated with the engine; improper coordination can lead to reduced drone engine power, increased fuel consumption, and increased carbon buildup.

[0003] Currently, exhaust pipes are mainly formed through welding, which results in high costs and long production cycles, hindering large-scale mass production. Figure 1 The product shown is an example used in 50cc-60cc drone engines. The components consist of two stamped side covers, an exhaust chamber, a connector, and two pre-cut exhaust pipes. Two screws are used to assemble and weld the components through the pipes. This process presents challenges in ensuring high strength, resistance to deformation or breakage, and flawless welds with perfect sealing. Furthermore, the stamping process requires five stamping dies and five stamping steps, with weld lengths reaching approximately 900mm. The process is complex, time-consuming, inefficient, and costly in terms of materials and processing. The large number of welds also increases the probability of defective products.

[0004] Another method is casting, which involves casting the two parts of the exhaust pipe, connecting them with screws, and sealing them with O-rings. Due to limitations in casting technology, exhaust pipes are often designed to be large, thick-walled, and heavy, posing a challenge for drones that prioritize lightweight design. Furthermore, the O-ring seals are prone to aging and failure under prolonged high-temperature conditions, leading to exhaust pipe leaks and damage.

[0005] A composite manufacturing process for drone engine exhaust pipes is now provided. Summary of the Invention

[0006] The summary section of this application is intended to provide a brief overview of the concepts, which will be described in detail in the detailed description section below. This summary section is not intended to identify key or essential features of the claimed technical solutions, nor is it intended to limit the scope of the claimed technical solutions.

[0007] To address the technical problems mentioned in the background section, some embodiments of this application provide a composite production process for unmanned aerial vehicle (UAV) engine exhaust pipes, comprising the following steps: S1: Mold design and manufacturing, manufacturing a die-casting mold comprising a multi-point sequential filling flow channel system, an exhaust groove system with a depth of 0.10-0.15mm, a combined cooling water channel and heating oil channel system, and a multi-directional core-pulling mechanism; S2: Melting and refining, placing ADC12 aluminum alloy in a melting furnace at 680±20°C for melting and holding, followed by rotary degassing and refining; S3: Die-casting, transferring the refined aluminum liquid at a temperature of 640±15°C into the die-casting machine chamber, with a mold temperature of 180-250°C, a slow injection speed of 0.2-0.4 m / s, a fast injection speed of 3.0-5.0 m / s, and an injection specific pressure of 85. Under MPa conditions, die casting is performed, and the exhaust pipe body is formed by the movement of mold sliders in multiple different directions to form an inner cavity, air inlet, air outlet, and screw passage; S4: holding pressure and cooling, after holding pressure for 10 seconds, the exhaust pipe body is ejected after cooling in the mold for 15 seconds; S5: post-processing, the ejected exhaust pipe body is de-gated, flash is removed, and specific edges are milled flat; S1, S2, S3, S4, and S5 are the production of the exhaust pipe body; S6: two side covers are manufactured by stamping metal sheets; S7: the exhaust pipe body and side covers are laser welded and shot blasted.

[0008] In some implementations, the combined temperature control system in S1 is to set up cooling water channels in the thick part of the mold and heating oil channels inside the core of the thin-walled part of the casting, and to control the temperature difference of the mold by cooling and heating by an external mold temperature controller.

[0009] In some implementations, the multi-directional core-pulling mechanism in S1 is a four-directional hydraulic core-pulling mechanism.

[0010] In some implementations, the rotary degassing in S2 is performed using either high-purity nitrogen or argon.

[0011] In some implementations, the die-casting machine used in S3 is a cold chamber die-casting machine with a tonnage of 800 tons or more.

[0012] In some implementations, the laser welding process parameters in S5 are: laser frequency of 20-60Hz, power of 80-180W, welding speed of 2.0-6.0mm / s, and the gap between castings before welding is less than 0.1mm.

[0013] In some implementations, the power is 120-140W.

[0014] In some implementations, the mold steel material used in S1 is H13, and the heat treatment process is HRC46-48.

[0015] In some embodiments, the mold temperature in S3 is 200-240°C.

[0016] In some implementations, the welding speed is 4-5 mm / s.

[0017] The beneficial effects of this application are as follows: By setting up an integrated die-casting structure, the exhaust pipe of the drone engine produced using the die-casting process improves production efficiency while reducing material costs. Furthermore, the combined production of die-casting and welding processes further simplifies the processing steps and time, improving production efficiency while reducing labor costs. This invention reduces production steps, significantly improves overall production efficiency, and markedly reduces production costs. It is particularly suitable for the large-scale and standardized production of drone engine exhaust pipes, and compared to welding processes, it avoids excessive weld points, improving overall strength and stability. Attached Figure Description

[0018] The accompanying drawings, which form part of this application, are used to provide a further understanding of the application and to make other features, objects, and advantages of the application more apparent. The illustrative embodiments and descriptions of this application are used to explain the application and do not constitute an undue limitation of the application.

[0019] Furthermore, throughout the accompanying drawings, the same or similar reference numerals denote the same or similar elements. It should be understood that the drawings are schematic, and the elements are not necessarily drawn to scale.

[0020] In the attached diagram:

[0021] Figure 1 It is a production process diagram;

[0022] Figure 2 This is a schematic diagram of the three-dimensional structure of the exhaust pipe;

[0023] Figure 3 This is a schematic diagram of the sliding of regions A and B of the exhaust chamber;

[0024] Figure 4 This is a schematic diagram of the sliding of region C of the exhaust chamber.

[0025] Figure label:

[0026] 1. Exhaust pipe body; 2. Side cover; 3. Air outlet pipe; 4. Screw through pipe; 5. Connection port; 6. Air inlet. Detailed Implementation

[0027] Embodiments of this disclosure will now be described in more detail with reference to the accompanying drawings. While some embodiments of this disclosure are shown in the drawings, it should be understood that this disclosure can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of this disclosure. It should be understood that the accompanying drawings and embodiments of this disclosure are for illustrative purposes only and are not intended to limit the scope of protection of this disclosure.

[0028] It should also be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings. Unless otherwise specified, the embodiments and features described in this disclosure can be combined with each other.

[0029] It should be noted that the concepts of "first" and "second" mentioned in this disclosure are used only to distinguish different devices, modules or units, and are not used to limit the order of functions performed by these devices, modules or units or their interdependencies.

[0030] It should be noted that the terms "a" and "a plurality of" used in this disclosure are illustrative rather than restrictive, and those skilled in the art should understand that, unless otherwise expressly indicated in the context, they should be understood as "one or more".

[0031] This disclosure will now be described in detail with reference to the accompanying drawings and embodiments.

[0032] A composite manufacturing process for an unmanned aerial vehicle (UAV) engine exhaust pipe includes the following steps: S1: Mold design and manufacturing, manufacturing a die-casting mold comprising a multi-point sequential filling runner system, an exhaust groove system with a depth of 0.10-0.15mm, a combined cooling water channel and heating oil channel system, and a multi-directional core-pulling mechanism; S2: Melting and refining, melting and holding ADC12 aluminum alloy in a melting furnace at 680±20°C, followed by rotary degassing and refining; S3: Die-casting, transferring the refined molten aluminum at a temperature of 640±15°C into the die-casting machine chamber, with a mold temperature of 180-250°C, a slow injection speed of 0.2-0.4 m / s, a fast injection speed of 3.0-5.0 m / s, and an injection specific pressure of 85. Under MPa conditions, die casting is performed, and the exhaust pipe body is formed by the movement of mold sliders in multiple different directions to form an inner cavity, air inlet, air outlet, and screw passage; S4: holding pressure and cooling, after holding pressure for 10 seconds, the exhaust pipe body is ejected after cooling in the mold for 15 seconds; S5: post-processing, the ejected exhaust pipe body is de-gated, flash is removed, and specific edges are milled flat; S1, S2, S3, S4, and S5 are the production of the exhaust pipe body; S6: two side covers are manufactured by stamping metal sheets; S7: the exhaust pipe body and side covers are laser welded and shot blasted.

[0033] For the runner and venting systems, a slit gate or multi-point sequential filling system optimized based on mold flow analysis is adopted, along with sufficient overflow grooves and venting grooves (0.10-0.15mm deep) located at the cavity end and slider mating points. If necessary, concentrated venting blocks can be used to increase the venting area. This ensures that the molten metal fills the entire complex thin-walled cavity smoothly and sequentially, effectively venting gases and fumes from the coating that evaporate at high temperatures within the cavity, preventing air entrapment, turbulence, and cold shuts, and preventing defects such as porosity and incomplete filling in the venting pipe walls of the thin-walled structure.

[0034] For the temperature control and cooling system, closed-loop cooling water channels and single-point cooling water are designed in thick parts of the mold (such as the mounting base) and inside the core. Closed-loop heating oil channels are designed inside the core in thin-walled areas of the casting. The mold temperature is controlled by an external circulating mold temperature controller and cooling water. The combination of water and oil channels controls the temperature difference in the mold, reducing aluminum runoff, casting deformation, and cold shuts caused by temperature differences. The cooling water channels reduce local temperatures, avoid local overheating, improve production efficiency, reduce hot spots in the casting, and prevent shrinkage cavities. For the action mechanism, a four-way precision slider or hydraulic core-pulling mechanism is used to achieve one-time molding and smooth demolding of complex internal and external features of the vent pipe.

[0035] For the die casting of the exhaust pipe, aluminum alloy of grade ADC12 can be used. Due to its good fluidity, resistance to thermal cracking, and mechanical properties, it is suitable for the production of thin-walled parts. The holding temperature inside the melting furnace is 680±20°C to ensure uniform alloy composition and good fluidity, while avoiding overheating that could lead to gas absorption and oxidation. High-purity nitrogen or argon is used for rotary degassing or the introduction of refining agents. This process aims to remove hydrogen and inclusions from the molten aluminum, significantly reducing internal porosity in the casting. The temperature of the molten aluminum entering the mold and then transferring to the injection chamber is 640±15°C. Care must be taken to avoid excessively high temperatures causing sticking to the mold, while excessively low temperatures result in poor fluidity and incomplete filling.

[0036] Simultaneously, based on the product's projected area and the required injection pressure, a cold chamber die-casting machine of 800 tons or more is used. The injection speed is controlled as follows: slow injection speed: 0.2-0.4 m / s; fast injection speed: 3.0-5.0 m / s. Gas is slowly expelled from the pressure chamber, followed by rapid filling after breaking through the inner gate, ensuring complete molding of thin-walled areas. Preheating temperature before production: 180-220°C; mold temperature control during continuous production: 200-250°C. Preheating prevents rapid cooling of the molten aluminum, and maintaining a stable mold temperature during production ensures consistent filling and casting quality. A water-based release agent is used for demolding, automatically sprayed, with controlled spray volume and time, followed by air blowing. The blowing time is 3-10 seconds. This forms a protective film for easy demolding and cools the mold. Precise control avoids excessive moisture lowering the mold temperature or generating gas. Subsequently, the pressure is maintained for about 10 seconds based on the workpiece wall thickness, and then ejected after a cooling time of 15 seconds to ensure that the thin-walled structure of the exhaust pipe has sufficient strength to eject without deformation or cracking.

[0037] The die-cast workpiece undergoes subsequent processing: hydraulic fixtures or robots are used for punching and grinding to remove excess gating system material and overflow trough material. The edges to be welded are milled smooth to standardize the dimensions for the next laser welding process and to remove the oxide layer from the areas to be welded.

[0038] To prevent the formation of a thick aluminum oxide layer in the air at the welding area after processing, which could hinder the welding process, the workpiece must be moved to the next welding and forming process as soon as possible.

[0039] Welding Process: It is recommended to use automated laser CNC welding equipment to weld the sections to be welded on both sides of the exhaust pipe. This aims to achieve high processing efficiency, standardize the welded exhaust pipe, and reduce the defect rate. Depending on the material and actual wall thickness, the laser welding process uses a laser frequency of 20Hz-80Hz, a power of 80W-230W, and a welding speed of 2.0ms-8.0ms. Appropriate fixtures must be used to secure the workpieces; this is crucial for accurate alignment during automated welding. Ensure the fixture applies force evenly across the entire weld length to avoid localized misalignment leading to incomplete welds. Ideally, the gap between the two workpieces should be less than 0.1mm after the fixture is secured. Ensure the weld is smooth, continuous, and of high strength, without perforation, deformation, or incomplete welds.

[0040] After the welded workpieces pass visual inspection and sealing tests, they can be processed by shot blasting. Shot blasting results in a smooth and aesthetically pleasing appearance and enhances surface hardness. This completes the overall composite processing flow.

[0041] The combined temperature control system in vent pipe S1 consists of cooling water channels in the thicker parts of the mold and heating oil channels inside the core in the thinner-walled parts of the casting. Cooling and heating are respectively achieved through an external mold temperature controller to control the mold temperature difference. The multi-directional core-pulling mechanism in vent pipe S1 is a four-way hydraulic core-pulling mechanism. The rotary degassing in vent pipe S2 uses either high-purity nitrogen or argon. The laser welding process parameters in vent pipe S5 are: laser frequency 20-60Hz, power 80-180W, welding speed 2.0-6.0mm / s, and the gap between castings before welding is less than 0.1mm. The vent pipe power is 120-140W. The mold steel material used in vent pipe S1 is H13, with a heat treatment process of HRC46-48°C, to ensure that the mold has high hardness, high wear resistance, good thermal fatigue strength, and creep resistance under high temperature and pressure, extending the mold life. The mold temperature in vent pipe S3 is 200-240°C. The welding speed for the exhaust pipe is 4-5 mm / s.

[0042] The exhaust pipe manufactured using this process includes an exhaust pipe body 1, an outlet pipe 3, a connector 5, and a screw-through pipe 4. The air inlet is located on the connector and is connected to the internal cavity of the exhaust pipe body. By setting the exhaust pipe body 1, outlet pipe 3, connector 5, and screw-through pipe 4 into an integrated die-casting structure, it can be directly produced as a single piece. The two simple metal side covers 2 are stamped. In short, only one die-casting mold and one stamping mold are needed to produce one exhaust pipe body 1 and two side covers 2, which completes the material preparation for the whole. Compared with existing welding and screw connections, this process improves work efficiency, reduces production costs, and enhances the stability of the overall connection.

[0043] Specifically, during mold development and die casting, the mold slide can be used as follows: Figure 3 The movement of regions A and B, as shown, allows the internal cavity of the exhaust pipe body 1 to be formed. Simultaneously, using a mold slider that matches the shape of the intake port 6 channel, it is possible to... Figure 4 The C region shown moves back and forth, inserting itself through the middle of the integrated topological structure formed by the screw-through tube 4, thus dividing the overall topological structure. After the molten aluminum cools and solidifies, the slider is pulled out, forming two independent screw-through tubes 4 on the left and right, thereby forming the air inlet 6 channel of the connection port 5. This design avoids undercutting and allows for demolding. Furthermore, after the slider in the C region leaves, its upper and lower spaces can be connected without affecting the airflow within the exhaust pipe body 1. Similarly, the screw through holes within the screw-through tube 4 can be formed by the slider's movement. The exhaust pipe design fully accommodates and considers mold development and the die-casting process, thus eliminating undercutting defects and allowing all surfaces to be smoothly formed and demolded.

[0044] The above description is merely a selection of preferred embodiments of this disclosure and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention involved in the embodiments of this disclosure is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the above-described inventive concept. For example, technical solutions formed by substituting the above-described features with (but not limited to) technical features with similar functions disclosed in the embodiments of this disclosure.

Claims

1. A composite manufacturing process for an unmanned aerial vehicle (UAV) engine exhaust pipe, comprising the following steps: S1: Mold design and manufacturing, manufacturing die casting molds including multi-point sequential filling runner system, venting groove system with a depth of 0.10-0.15mm, combined cooling water channel and heating oil channel system and multi-directional core pulling mechanism; The runner system adopts a slot gate or a multi-point sequential filling gating system. The size and direction of the runner, sprue, and ingate need to be optimized through mold flow analysis. The venting system is equipped with sufficient overflow grooves and venting grooves at the end of the cavity and the sliding block mating area. If necessary, a centralized venting block can be used to increase the venting area. The cooling system is designed with closed-loop cooling water channels and single-point cooling water in the thick parts of the mold and inside the core. In the thin-walled parts of the casting, a closed-loop heating oil channel is designed inside the core. The mold temperature is controlled by an external circulating mold temperature controller and cooling water. S2: Melting and refining: ADC12 aluminum alloy is placed in a melting furnace at 680±20°C for melting and holding, followed by rotary degassing and refining. S3: Die casting. The refined aluminum liquid at a temperature of 640 ± 15°C is transferred into the die casting machine chamber. Die casting is carried out under the conditions of mold temperature of 180-250°C, slow injection speed of 0.2-0.4 m / s, fast injection speed of 3.0-5.0 m / s, and injection pressure of 85 MPa. The exhaust pipe body is formed into an inner cavity, air inlet, air outlet, and screw passage by moving the mold slider in multiple different directions. S4: Pressure holding and cooling. After holding pressure for 10 seconds, cool in the mold for 15 seconds and then eject the main body of the exhaust pipe. S5: Post-processing, removing gates and flash from the ejected exhaust pipe body, and milling specific edges; S1, S2, S3, S4, and S5 are the main components of the exhaust pipe. S6: Two side covers are manufactured by stamping metal sheets; S7: The exhaust pipe body and side cover are laser welded and shot blasted.

2. The composite manufacturing process for an unmanned aerial vehicle engine exhaust pipe according to claim 1, characterized in that: The combined temperature control system in S1 has cooling water channels in the thick part of the mold and heating oil channels inside the core in the thin-walled part of the casting. The external mold temperature controller is used to cool and heat the mold respectively to control the temperature difference.

3. The composite manufacturing process for an unmanned aerial vehicle engine exhaust pipe according to claim 1, characterized in that: The multi-directional core-pulling mechanism in S1 is a four-directional hydraulic core-pulling mechanism.

4. The composite manufacturing process for an unmanned aerial vehicle engine exhaust pipe according to claim 1, characterized in that: The rotary degassing in S2 uses either high-purity nitrogen or argon.

5. The composite manufacturing process for an unmanned aerial vehicle engine exhaust pipe according to claim 1, characterized in that: The die-casting machine used in S3 is a cold chamber die-casting machine with a capacity of 800 tons or more.

6. The composite manufacturing process for an unmanned aerial vehicle engine exhaust pipe according to claim 1, characterized in that: The laser welding process parameters in S5 are: laser frequency of 20-60Hz, power of 80-180W, welding speed of 2.0-6.0mm / s, and the gap between the castings before welding is less than 0.1mm.

7. The composite manufacturing process for an unmanned aerial vehicle engine exhaust pipe according to claim 6, characterized in that: The power is 120-140W.

8. The composite manufacturing process for an unmanned aerial vehicle engine exhaust pipe according to claim 1, characterized in that: The mold steel material used in S1 is H13, and the heat treatment process is HRC46-48°.

9. The composite manufacturing process for an unmanned aerial vehicle engine exhaust pipe according to claim 1, characterized in that: The mold temperature in S3 is 200-240°C.

10. The composite manufacturing process for an unmanned aerial vehicle engine exhaust pipe according to claim 6, characterized in that: The welding speed is 4-5 mm / s.

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