High-force spring thermoforming device and its thermoforming method for aerospace valves

Abstract

This invention provides a hot-pressing device and method for high-force springs used in aerospace valves, comprising: a base, a spring bushing, a pressure rod, and a locking sleeve. First, the bushing is placed in the base, followed by the alloy steel wire spring and the pressure rod. Then, the locking sleeve is screwed on for pre-fixation. A press-fitting machine is used to press the pressure rod to the hot-pressing height, and then the locking sleeve is tightened. The spring is then placed in a furnace for heat treatment, kept at that temperature, and air-cooled to room temperature. Finally, the press-fitting machine is used to press the pressure rod again, and the locking sleeve is removed to extract the spring. This invention, through tooling and the hot-pressing process, ensures that the spring's end face is uniformly subjected to axial force during the pressing process, avoiding friction between the spring's plating layer and the tooling during pressure and release. The base and locking sleeve ensure the hot-pressing dimensions, eliminating the need for external pressure input during heating. Multiple parts can be hot-pressed simultaneously, depending on the size of the furnace's uniform temperature. This method is suitable for the small-batch, multi-variety production of high-force springs for aerospace valves.

Description

Technical Field

[0001] This invention relates to the field of spring hot pressing technology, specifically to a high-force spring hot pressing device and its hot pressing method for aerospace valves. Background Technology

[0002] Currently, the compression and assembly process of high-force springs typically utilizes a mandrel-type screw tooling with a base. After passing through the spring and adding a washer, the spring is compressed to the desired height by tightening the lock nut. Measurement is then taken using calipers before the spring is heated in a furnace. This entire process is time-consuming and labor-intensive, the tooling has a short lifespan, the locking structure is prone to seizing, the plating surface is easily scratched, and disassembly and assembly are difficult. With the increasingly demanding tasks of aerospace research and production, these efficiency bottlenecks urgently need to be addressed.

[0003] While some hot pressing methods exist in other industries, these methods are not suitable for high-precision, high-elasticity, and low-winding-ratio plated springs, and the hot pressing process requirements differ, failing to meet the application needs of this specific professional field.

[0004] Therefore, the market needs a high-force spring hot pressing device and its hot pressing method for aerospace valves that can be applied to the hot pressing of plated springs with high precision, low winding ratio, small outer diameter, and a force of over 5000N, and achieve precise control of the hot-pressed spring dimensions. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the purpose of this invention is to provide a high-force spring hot-pressing device for aerospace valves and its hot-pressing method.

[0006] A high-force spring thermocompression device for aerospace valves according to the present invention includes: a base 1, a spring bushing 2, a pressure rod 3, a locking sleeve 4, and a spring 5;

[0007] The spring bushing 2 is placed in the base 1, the spring 5 is placed inside the bushing, the pressure rod 3 is located above the end face of the spring 5 and is embedded in the locking sleeve 4. After being pressed, it moves downward and contacts the spring bushing 2, and is fixed and limited by the locking sleeve 4 and the base 1.

[0008] Preferably, the base 1, spring bushing 2, pressure rod 3, locking sleeve 4, and spring 5 are all made of martensitic precipitation hardening stainless steel.

[0009] Both the base 1 and the locking sleeve 4 are hexagonal structures.

[0010] Preferably, after the pressure bar 3 is pressed to the hot pressing height by the pressure assembly machine, the height is locked by the base 1 and the locking sleeve 4. The tooling assembly process is not affected by the spring force, and the hot pressing size remains unchanged after the pressure assembly machine is depressurized.

[0011] Preferably, the surface roughness of the contact surface between the bushing 2 and the spring 5 is less than 3.2μm, the pressure rod 3 has a small boss for spring positioning, the height of which is greater than the diameter of the steel wire, and the top of the boss is rounded with a radius of R0.5 for spring positioning to prevent the edge of the boss from rubbing against the inner ring plating of the spring.

[0012] Preferably, the spring 5 is a chemically nickel-plated alloy steel wire compression spring with a winding ratio of less than 4, a force value greater than 5000N, and a perpendicularity requirement of ≤0.2mm.

[0013] According to the present invention, a high-force spring for aerospace valves is hot-pressed using the aforementioned high-force spring hot-pressing device. The hot-pressing method includes:

[0014] Step S1: Assemble a hot pressing device with springs;

[0015] Step S2: The hot-pressing device is subjected to hot-pressing treatment to obtain the hot-pressed spring;

[0016] Step S3: Inspect the quality of the spring after hot pressing.

[0017] Preferably, the gap between the spring 5 and the base 1 and the hot pressing height are adjusted by the spring bushing 2, thereby achieving control over the accuracy of the hot pressing dimensions.

[0018] The dimensional accuracy can be controlled within 0.1 mm.

[0019] Preferably, step S1 includes:

[0020] Step S1.1: Place the spring bushing 2 in the base 1, put in the spring 5 to be processed, install the pressure rod 3, and put on the locking sleeve 4. When the spring is not under force, pre-tighten and fix the spring bushing 2 and the locking sleeve 4.

[0021] Step S1.2: Place the hot pressing device in the center of the press base and press the pressure rod 3 until the pressure rod 3 contacts the spring bushing 2 and stops moving;

[0022] Step S1.3: Use a wrench to fix the hexagonal structure of base 1, and at the same time use a wrench to tighten the locking sleeve;

[0023] Step S1.4: Loosen the press and remove the hot press device with springs;

[0024] Repeat steps S1.1 to S1.4 to complete the assembly of all springs 5.

[0025] Preferably, step S2 includes:

[0026] Step S2.1: Turn on the box furnace and preheat the equipment to the process set temperature;

[0027] Step S2.2: Place the hot pressing device equipped with springs vertically and evenly in the workpiece tray;

[0028] Step S2.3: Place the workpiece tray into the uniform temperature zone of the box furnace for heat preservation;

[0029] Step S2.4: After the predetermined time, remove the workpiece tray and air cool it;

[0030] Step S2.5: Place the hot-pressed device with the spring into the center of the press base and apply assembly pressure to the pressure rod;

[0031] Step S2.6: Loosen the locking sleeve to the height of the pressure rod with a wrench, release the pressure in the press machine, and remove the hot pressing device;

[0032] Step S2.7: Unscrew the locking sleeve and remove the spring.

[0033] Preferably, step S3 includes inspecting the surface of the spring plating for defects such as scratches and cracks; and checking that the force, dimensions, and perpendicularity meet the requirements of the drawings.

[0034] Preferably, the hot pressing involves pressing the spring to below the minimum working height, with the heat treatment temperature being 50–100°C lower than the heat treatment temperature after electroless nickel plating, and the time being 5–7 hours.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] 1. This invention uses an inner bushing to precisely limit and control the hot pressing dimensions. The matching structure with different hardnesses avoids the tooling from seizing after heating. With the help of a reasonable heat treatment process, the heat treatment process after nickel plating of the spring is guaranteed to be stable, ensuring the reliability of the spring. The tooling can be reused, the dimensional accuracy remains unchanged, and the cost of use is reduced.

[0037] 2. To avoid wear on the spring plating during hot pressing, this invention uses an inner bushing and a pressure rod to position the spring. The pressure rod is loaded and pressed down to counteract the spring's elastic force before installation or disassembly. Compared with existing mandrel-type positioning fixtures, this avoids the torque of the locking nut during spring installation and disassembly, thus improving assembly efficiency. Attached Figure Description

[0038] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0039] Figure 1 This is a cross-sectional view of the spring hot pressing device, which is the main feature of this invention.

[0040] Figure 2 This is a cross-sectional view of the base, which is the main feature of this invention;

[0041] Figure 3 This is a top view of the base, which is the main feature of this invention.

[0042] Figure 4 This is a cross-sectional view that mainly illustrates the spring bushing of the present invention;

[0043] Figure 5 This is a top view that mainly illustrates the spring bushing of the present invention;

[0044] Figure 6 This is a cross-sectional view that mainly illustrates the push rod of the present invention;

[0045] Figure 7 This is a schematic diagram illustrating the spring, which is the main feature of this invention.

[0046] Figure 8 This is a cross-sectional view that mainly illustrates the locking sleeve of the present invention;

[0047] Figure 9 This is a top view of the locking sleeve, which is the main feature of this invention.

[0048] Reference numerals in the attached diagram: 1. Base; 2. Spring bushing; 3. Top rod; 4. Locking sleeve; 5. Spring. Detailed Implementation

[0049] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the scope of protection of the present invention.

[0050] This invention utilizes tooling combined with a hot-pressing process to ensure uniform axial force on the end face of the spring during compression. This avoids friction between the spring plating layer and the tooling during compression and release. The base and locking sleeve ensure the hot-pressed dimensions, eliminating the need for external pressure input during heating. Multiple parts can be hot-pressed simultaneously based on the uniform temperature and dimensions of the heating furnace. It is suitable for the production of small batches of high-force springs of various types for aerospace valves. It is particularly suitable for the hot-pressing of high-precision, low-winding-ratio, small-outer-diameter springs with a strength of 5000N or higher after plating, achieving precise control of the hot-pressed spring dimensions.

[0051] According to the present invention, a high-force spring thermocompression device for aerospace valves is provided, such as... Figure 1As shown, the fixture includes: a base 1, a spring bushing 2, a pressure rod 3, a locking sleeve 4, and a spring 5. The spring bushing 2 is placed in the base 1, the spring 5 is placed inside the bushing, and the pressure rod 3 is located above the end face of the spring 5 and embedded in the locking sleeve 4. When compressed, the pressure rod 3 moves downwards and contacts the spring bushing 2, and is fixedly positioned to the base 1 by the locking sleeve 4. After the pressure rod 3 is pressed to the hot-pressed height by the press-fitting machine, the height is locked by the base 1 and the locking sleeve 4. During tooling assembly, the fixture is not affected by the spring force, and the hot-pressed dimensions remain fixed after the press-fitting machine releases pressure. The base 1, spring bushing 2, pressure rod 3, locking sleeve 4, and spring 5 are all made of martensitic precipitation-hardening stainless steel, possessing sufficient strength to withstand the load of high-force springs used in aerospace valves during hot pressing without deformation. They also have a certain degree of corrosion resistance, do not rust when stored at room temperature, ensure surface finish, and will not damage the spring plating surface during use. The precipitation-hardening martensitic stainless steel materials used undergo heat treatment at different temperatures to achieve different hardness levels, such as... Figure 2 and Figure 8 As shown, the precipitation-hardening martensitic stainless steel materials used in the base 1 and the locking sleeve 4 undergo heat treatment at different temperatures to achieve different hardnesses, ensuring that the base 1 and the locking sleeve 4 will not seize up after hot pressing, while maintaining the same material strength and dimensions.

[0052] like Figure 2 and Figure 4 As shown, the spring bushing 2 is installed inside the base 1. The gap between the spring 5 and the base 1, as well as the hot-pressing height, are adjusted via the spring bushing 2, thereby controlling the dimensional accuracy of the hot-pressing process. This dimensional accuracy can be controlled to within 0.1 mm. Figure 3 and Figure 9 As shown, both the base 1 and the locking sleeve 4 are hexagonal structures, facilitating the fixing or disassembly of the base 1 and the locking sleeve 4 using a wrench. Figure 1 and Figure 6 As shown, the surface roughness of the contact surface between the bushing 2 and the spring 5 is less than 3.2 μm. The pressure rod 3 has a small boss for spring positioning, with a height greater than the wire diameter. The top of the boss has a rounded corner R0.5 for spring positioning and to prevent the boss edges from rubbing against the inner ring plating of the spring. The spring 5 is a chemically nickel-plated alloy steel wire compression spring with a winding ratio of less than 4, a force greater than 5000 N, and a perpendicularity requirement of ≤0.2 mm.

[0053] The hot pressing method of the high force value spring hot pressing device for aerospace valves of the present invention includes: first, placing the bushing into the base, placing the alloy steel wire spring and the pressure rod, then tightening the locking sleeve for pre-fixation, using a press-fitting machine to press the pressure rod to the hot pressing height and then tightening the locking sleeve, placing it in a furnace for heat treatment, keeping it at a certain temperature and then air cooling to room temperature, then using a press-fitting machine to press the pressure rod and then removing the locking sleeve to take out the spring.

[0054] A method for hot-pressing a high-force spring for aerospace valves according to the present invention includes:

[0055] Step S1: Assemble a hot pressing device with a spring. Step S1 includes:

[0056] Step S1.1: Place the spring bushing 2 in the base 1, put in the spring 5 to be processed, install the pressure rod 3, and put on the locking sleeve 4. When the spring is not under force, pre-tighten and fix the spring bushing 2 and the locking sleeve 4.

[0057] Step S1.2: Place the hot pressing device in the center of the press base and press the pressure rod 3 until the pressure rod 3 contacts the spring bushing 2 and stops moving.

[0058] Step S1.3: Use a wrench to fix the hexagonal structure of the base 1, and at the same time use a wrench to tighten the locking sleeve.

[0059] Step S1.4: Loosen the press and remove the hot press device with springs.

[0060] Repeat steps S1.1 to S1.4 to complete the assembly of all springs 5.

[0061] Step S2: The hot-pressing device is used to perform hot-pressing treatment to obtain the hot-pressed spring. The hot pressing involves compressing the spring to below its minimum working height, with the holding temperature being 50-100°C lower than the heat treatment temperature after electroless nickel plating, and the time being 5-7 hours. Step S2 includes:

[0062] Step S2.1: Turn on the box furnace and preheat the equipment to the process set temperature.

[0063] Step S2.2: Place the hot pressing device with springs vertically and evenly in the workpiece tray.

[0064] Step S2.3: Place the workpiece tray into the uniform temperature zone of the box furnace for heat preservation.

[0065] Step S2.4: After the predetermined time, remove the workpiece tray and air cool it.

[0066] Step S2.5: Place the hot-pressed device with the spring into the center of the press base and apply assembly pressure to the pressure rod.

[0067] Step S2.6: Loosen the locking sleeve to the height of the pressure rod with a wrench, release the pressure in the press machine, and remove the hot pressing device.

[0068] Step S2.7: Unscrew the locking sleeve and remove the spring.

[0069] Step S3: Inspect the quality of the hot-pressed spring. Step S3 includes inspecting the surface of the spring plating for defects such as scratches and cracks. The force, dimensions, and perpendicularity must meet the drawing requirements.

[0070] This invention employs a precise inner bushing to control the hot-pressing dimensions. The use of different hardness mating structures prevents the tooling from seizing up after heating. Combined with a reasonable heat treatment process, the heat treatment effect after nickel plating of the spring is stable, ensuring the reliability of the spring. The tooling is reusable with consistent dimensional accuracy, reducing operating costs. To prevent wear on the spring plating during hot pressing, an inner bushing and a pressure rod are used to position the spring. The pressure rod is loaded and pressed down to counteract the spring's elastic force before installation or disassembly. Compared to existing mandrel-type positioning tooling, this avoids the torque of the locking nut during spring assembly and disassembly, improving assembly efficiency.

[0071] In the description of this application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application 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 limitations on this application.

[0072] Those skilled in the art will understand that, besides implementing the system and its various devices, modules, and units provided by this invention in the form of purely computer-readable program code, the same functions can be achieved entirely through logical programming of the method steps, making the system and its various devices, modules, and units of this invention function in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, and embedded microcontrollers. Therefore, the system and its various devices, modules, and units provided by this invention can be considered as a hardware component, and the devices, modules, and units included therein for implementing various functions can also be considered as structures within the hardware component; alternatively, the devices, modules, and units for implementing various functions can be considered as both software modules implementing the method and structures within the hardware component.

[0073] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A method for hot-pressing a high-force spring for aerospace valves, characterized in that, The invention includes a high-force spring hot-pressing device for aerospace valves, the hot-pressing device comprising: a base (1), a spring bushing (2), a pressure rod (3), a locking sleeve (4), and a spring (5); The spring bushing (2) is placed in the base (1), the spring (5) is placed in the spring bushing (2), the pressure rod (3) is located above the end face of the spring (5) and is embedded in the locking sleeve (4). After being pressed, it moves downward and contacts the spring bushing (2). It is fixed and limited by the locking sleeve (4) and the base (1). The hot pressing method includes: Step S1: Assemble a hot pressing device with springs; Step S2: The hot-pressing device is subjected to hot-pressing treatment to obtain the hot-pressed spring; Step S3: Inspect the quality of the spring after hot pressing; Step S1 includes: Step S1.1: Place the spring bushing (2) in the base (1), put in the spring to be processed (5), install the pressure rod (3), put on the locking sleeve (4), and pre-tighten and fix the spring bushing (2) and the locking sleeve (4) when the spring is not under force; Step S1.2: Place the hot pressing device in the center of the press base and press the pressure rod (3) until the pressure rod (3) contacts the spring bushing (2) and stops moving; Step S1.3: Use a wrench to fix the hexagonal structure of the base (1), and at the same time use a wrench to tighten the locking sleeve; Step S1.4: Loosen the press and remove the hot press device with springs; Repeat steps S1.1 to S1.4 to complete the assembly of all springs (5).

2. The high-force spring hot-pressing method for aerospace valves according to claim 1, characterized in that, The base (1), spring bushing (2), pressure rod (3), locking sleeve (4), and spring (5) are all made of martensitic precipitation hardening stainless steel. Both the base (1) and the locking sleeve (4) are hexagonal structures.

3. The high-force spring hot-pressing method for aerospace valves according to claim 1, characterized in that, After the pressure bar (3) is pressed to the hot pressing height by the pressure machine, the height is locked by the base (1) and the locking sleeve (4). The tooling is not affected by the spring force during the assembly process. When the pressure machine is depressurized, the hot pressing size remains unchanged.

4. The high-force spring hot-pressing method for aerospace valves according to claim 1, characterized in that, The surface roughness of the contact surface between the spring bushing (2) and the spring (5) is less than 3.2 μm. The pressure rod (3) has a small boss for spring positioning and its height is greater than the diameter of the steel wire.

5. The high-force spring hot-pressing method for aerospace valves according to claim 1, characterized in that, The spring (5) is a chemically nickel-plated alloy steel wire compression spring with a winding ratio of less than 4, a force value greater than 5000N, and a perpendicularity requirement of ≤0.2mm.

6. The high-force spring hot-pressing method for aerospace valves according to claim 1, characterized in that, The gap between the spring (5) and the base (1) and the hot pressing height are adjusted by the spring bushing (2), thereby completing the control of the hot pressing dimension accuracy; The dimensional accuracy can be controlled within 0.1 mm.

7. The high-force spring hot-pressing method for aerospace valves according to claim 1, characterized in that, Step S2 includes: Step S2.1: Turn on the box furnace and preheat the equipment to the process set temperature; Step S2.2: Place the hot pressing device equipped with springs vertically and evenly in the workpiece tray; Step S2.3: Place the workpiece tray into the uniform temperature zone of the box furnace for heat preservation; Step S2.4: After the predetermined time, remove the workpiece tray and air cool it; Step S2.5: Place the hot-pressed device with the spring into the center of the press base and apply assembly pressure to the pressure rod; Step S2.6: Loosen the locking sleeve to the height of the pressure rod with a wrench, release the pressure in the press machine, and remove the hot pressing device; Step S2.7: Unscrew the locking sleeve and remove the spring.

8. The high-force spring hot-pressing method for aerospace valves according to claim 1, characterized in that, Step S3 includes inspecting the surface of the spring plating for scratches, cracks, or other defects; and verifying that the force, dimensions, and perpendicularity meet the drawing requirements. The hot pressing involves pressing the spring to below its minimum working height, with the holding temperature being 50–100°C lower than the heat treatment temperature after electroless nickel plating, and the time being 5–7 hours.

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