A precision machining method for an ultrathin-wall beryllium pipe part

Abstract

The application discloses a precision machining method for an ultrathin-wall beryllium pipe part and belongs to the technical field of pipe part machining. The method specifically comprises the following steps: rough turning a first outer circular surface and an inner hole, first-time aging treatment, semi-precision turning of the first outer circular surface, semi-precision milling of a second outer circular surface, second-time aging treatment, precision milling of the second outer circular surface and a circular arc transition surface, precision turning of the inner hole and an end surface, precision turning of the first outer circular surface and milling. The application avoids surface cracking or cracking and deformation of the ultrathin-wall beryllium pipe by designing special tooling and processing the outer circular surface of the beryllium pipe in regions.

Description

Technical Field

[0001] This invention belongs to the field of tubular parts processing technology, and particularly relates to a precision machining method for ultra-thin-walled beryllium tube parts. Background Technology

[0002] As a component made of rare and lightweight beryllium metal with high elastic modulus, high melting point, high specific stiffness, ultra-thin-walled beryllium tubes are the core components of major testing equipment and are the heart of such equipment.

[0003] Beryllium is a brittle metal material, which is prone to surface damage, cracks, and chipping during machining. Due to the thin walls, high precision requirements, poor structural rigidity, and weak strength of beryllium tube parts, as well as the strict requirements of the operating environment and the extremely high quality requirements of the parts, they are very susceptible to stress, heat, cutting, stress deformation, and cracking during machining. Currently, there are no corresponding precision machining technologies available abroad.

[0004] The existing machining method for tubular parts is as follows: blank → rough turning of inner hole → rough turning of outer diameter → aging treatment → finish turning of inner hole → finish turning of outer diameter. Using the existing machining method for tubular parts to process brittle ultrathin-walled beryllium tubes is prone to cracking and scrapping, and the product accuracy cannot meet the usage requirements. Therefore, there is an urgent need to develop a precision machining method for ultrathin-walled beryllium tube parts. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention proposes a precision machining method for ultra-thin-walled beryllium tube parts. By designing specialized tooling and machining the outer circular surface of the beryllium tube in sections, the surface cracking, fissures, or deformation of the ultra-thin-walled beryllium tube can be avoided.

[0006] This invention proposes a precision machining method for ultra-thin-walled beryllium tube parts. The outer circular surface of the beryllium tube includes two first outer circular surfaces, two arc transition surfaces, and one second outer circular surface. Each end of the second outer circular surface is connected to an arc transition surface, and the other end of each arc transition surface is connected to a first outer circular surface. Multiple reinforcing ribs with equal spacing are provided on the second outer circular surface.

[0007] The method includes the following steps:

[0008] Step S1: The pre-treated beryllium tube is assembled on two first fixtures using a double-center clamping method. The clearance between the two first fixtures and the beryllium tube is ≤0.05mm, and the perpendicularity between the two first fixtures and the outer circle of the beryllium tube is ≤0.05mm. Then, the beryllium tube is rough machined on the first outer circle surface and the inner hole.

[0009] The first tooling is an end cap with a central hole;

[0010] Step S2: Remove the first tooling and perform the first aging treatment on the beryllium tube that has been rough-machined on the first outer cylindrical surface and inner hole;

[0011] Step S3: Use the first tooling and the second tooling to fix the beryllium tube after the first aging treatment. The outer diameter runout of the fixed beryllium tube is ≤0.05mm. Then, the first outer diameter surface of the beryllium tube is semi-finish machined.

[0012] The second tooling is a mandrel with a central shaft hole. One end of the mandrel is provided with a clamping platform protruding from the outer periphery of the mandrel. The side of the clamping platform near the other end of the mandrel is provided with a first 60° conical surface. The other end of the mandrel is provided with a long step, and an external thread is provided at a position connected to the long step and away from the end face of the mandrel.

[0013] Step S4: The beryllium tube, which has been semi-finish-machined on the first outer cylindrical surface, is semi-finish-milled on the second outer cylindrical surface to form a plurality of equally spaced reinforcing ribs on the second outer cylindrical surface of the beryllium tube;

[0014] Step S5: Remove the first and second tooling, and perform a second aging treatment on the beryllium tube that has been semi-finish milled on the second outer cylindrical surface;

[0015] Step S6: Use the first tooling and the second tooling to fix the beryllium tube after the second aging treatment. The outer diameter runout of the fixed beryllium tube is ≤0.03mm. Then, perform precision milling on the second outer diameter surface and the arc transition surface of the beryllium tube after the second aging treatment.

[0016] Step S7: The third tooling is fitted onto the outer periphery of the beryllium tube fixed by the first and second toolings and bonded together. Wax is injected into the gap between the third tooling and the beryllium tube through the wax injection port of the third tooling. After the wax solidifies, the first and second toolings are removed to obtain the beryllium tube fixed by the third tooling. Then, the inner hole and end face of the beryllium tube are precision machined.

[0017] The third tooling is a cylindrical ring without clamping force. The inner surfaces of both ends of the cylindrical ring are provided with steps protruding from the inner surface of the cylindrical ring, forming stepped inner holes. Each step has multiple equally spaced first grooves, the depth of which is less than the height of the step. Multiple wax injection ports penetrating the side of the cylindrical ring are provided on its side. The clearance between the inner surface of the cylindrical ring and the beryllium tube is ≥0.05mm, and the diameter of the stepped inner hole is equal to the outer diameter of the beryllium tube.

[0018] Step S8: Remove the third tooling, then insert the fourth tooling into the inner hole of the beryllium tube with its inner hole and end face precision machined. The clearance between the fourth tooling and the beryllium tube is ≤0.05mm. Inject wax into the gap between the fourth tooling and the beryllium tube through one end of the second groove of the fourth tooling. After the wax solidifies, insert one end of the long step of the second tooling into the central shaft hole of the fourth tooling from one end of the 60° tapered hole of the fourth tooling, and use the first tooling to fix the other end of the beryllium tube, thus obtaining a beryllium tube fixed by the first tooling, the second tooling and the fourth tooling. Then, precision machine the first outer cylindrical surface of the beryllium tube.

[0019] The fourth tooling is a cylinder with a central shaft hole. The inner surface of one end of the fourth tooling is provided with a second 60° conical surface that matches the first 60° conical surface to form a 60° conical hole. The outer periphery of the fourth tooling is provided with a plurality of equally spaced second grooves. The depth of each second groove is less than half the difference between the outer diameter and the inner diameter of the fourth tooling.

[0020] Step S9: Remove the first tooling, the second tooling and the fourth tooling, and perform chemical milling on the beryllium tube that has been precision machined on the first outer cylindrical surface.

[0021] According to the precision machining method for ultra-thin-walled beryllium tube parts of the present invention, in step S1, the process parameters for rough machining the first outer cylindrical surface of the beryllium tube are as follows:

[0022] The tool tip radius is R0.1mm~R0.3mm, the depth of cut is 0.05~0.2mm, the rotation speed is 200~500r / min, the feed rate is 0.01~0.03mm / r, and the machining allowance is 0.1~0.3mm.

[0023] According to the precision machining method for ultra-thin-walled beryllium tube parts of the present invention, the process parameters for rough machining the inner hole of the beryllium tube in step S1 are as follows:

[0024] The tool tip radius is R0.1mm~R0.3mm, the depth of cut is 0.05~0.2mm, the spindle speed is 200~500r / min, the feed rate is 0.01~0.03mm / r, and the machining allowance is 0.05~0.15mm.

[0025] According to the precision machining method for ultra-thin-walled beryllium tube parts of the present invention, in step S3, the process parameters for semi-finish machining the first outer cylindrical surface of the beryllium tube are as follows:

[0026] The tool tip radius is R0.1mm~R0.2mm, the depth of cut is 0.05~0.15mm, the spindle speed is 200~300r / min, the feed rate is 0.01~0.03mm / r, and the machining allowance is 0.05~0.2mm.

[0027] According to the precision machining method for ultra-thin-walled beryllium tube parts of the present invention, in step S4, the process parameters for semi-finish milling the second outer surface of the beryllium tube after semi-finish turning of the first outer surface are as follows:

[0028] The cutting depth is 0.05-0.15 mm, the rotation speed is 500-800 r / min, the feed rate is 100-300 mm / min, and the machining is carried out layer by layer until the reserved machining allowance is 0.1-0.3 mm.

[0029] According to the precision machining method for ultra-thin-walled beryllium tube parts of the present invention, in step S6, the process parameters for precision milling the second outer cylindrical surface and the arc transition surface of the beryllium tube after the second aging treatment are as follows:

[0030] The cutting depth is 0.05–0.1 mm, the rotation speed is 600–1500 r / min, and the feed rate is 50–200 mm / min.

[0031] According to the precision machining method for ultra-thin-walled beryllium tube parts of the present invention, in step S7, the process parameters for precision machining the inner hole and end face of the beryllium tube are as follows:

[0032] The tool tip radius is ≤R0.1mm, the cutting depth is 0.05~0.1mm, the rotation speed is 600~1500r / min, and the feed rate is 50~200mm / min.

[0033] According to the precision machining method for ultra-thin-walled beryllium tube parts of the present invention, in step S8, the process parameters for precision machining the first outer cylindrical surface of the beryllium tube are as follows:

[0034] The tool tip radius is ≤R0.1mm, the cutting depth is 0.05~0.1mm, the rotation speed is 500~1000r / min, and the feed rate is 50~200mm / min.

[0035] According to the precision machining method for ultra-thin-walled beryllium tube parts of the present invention, in step S9, the beryllium tube with the first outer cylindrical surface precision machined is subjected to chemical milling treatment for 1-3 minutes.

[0036] The solution proposed in this invention has the following technical effects:

[0037] This invention avoids surface cracking, fissures, and deformation of ultra-thin-walled beryllium tubes by designing specialized tooling and processing the outer circumference of the beryllium tube in sections.

[0038] Furthermore, the ultrathin-walled beryllium tubes obtained using the method of this invention have a wall thickness ≤0.8mm, a form and position accuracy ≤0.02mm, and a dimensional accuracy ≤0.03mm, meeting the high-precision requirements of ultrathin-walled beryllium tubes and achieving an overall total leakage rate ≤0.5~2.5×10⁻¹¹ Pa. 3 / s, for product applications in harsh environments with an ultimate vacuum degree ≤3~8×10-8Pa. Attached Figure Description

[0039] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0040] Figure 1 This is a schematic diagram of the structure of a beryllium tube obtained by a precision machining method for ultra-thin-walled beryllium tube parts according to one embodiment of the present invention.

[0041] Figure 2 yes Figure 1 Enlarged schematic diagram of the central reinforcing rib.

[0042] Figure 3 This is a schematic diagram of the structure of the first tooling in a precision machining method for ultra-thin-walled beryllium tube parts according to an embodiment of the present invention.

[0043] Figure 4 This is a schematic diagram of the structure of the first tooling and the beryllium tube to be processed after assembly in a precision machining method for ultra-thin wall beryllium tube parts according to an embodiment of the present invention.

[0044] Figure 5 This is a schematic diagram of the structure of the second tooling in a precision machining method for ultra-thin-walled beryllium tube parts according to one embodiment of the present invention.

[0045] Figure 6 This is a schematic diagram of the structure after the first and second tooling are assembled with the beryllium tube to be processed in a precision machining method for ultra-thin-walled beryllium tube parts according to an embodiment of the present invention.

[0046] Figure 7 This is a schematic diagram of the third tooling in a precision machining method for ultra-thin-walled beryllium tube parts according to one embodiment of the present invention.

[0047] Figure 8 This is a schematic diagram of the structure after the first tooling, the second tooling and the third tooling are assembled with the beryllium tube to be processed in a precision machining method for ultra-thin wall beryllium tube parts according to an embodiment of the present invention.

[0048] Figure 9 This is a schematic diagram of the structure of the third tooling and the beryllium tube to be processed after assembly in a precision machining method for ultra-thin wall beryllium tube parts according to an embodiment of the present invention.

[0049] Figure 10This is a schematic diagram of the fourth tooling in a precision machining method for ultra-thin-walled beryllium tube parts according to one embodiment of the present invention.

[0050] Figure 11 This is a schematic diagram of the structure after the first tooling, the second tooling and the fourth tooling are assembled with the beryllium tube to be processed in a precision machining method for ultra-thin wall beryllium tube parts according to an embodiment of the present invention.

[0051] Wherein, 1-first outer circular surface, 2-circular arc transition surface, 3-second outer circular surface, 4-reinforcing rib, 5-first tooling, 6-second tooling, 7-clamping platform, 8-first 60° conical surface, 9-long step, 10-external thread, 11-third tooling, 12-step inner hole, 13-first groove, 14-wax injection port, 15-fourth tooling, 16-second 60° conical surface, 17-second groove, 18-water channel, 19-nut. Detailed Implementation

[0052] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0053] The purpose of this embodiment is to propose a machining method for high-precision ultra-thin-walled tube parts made of rare, lightweight, and brittle beryllium metal with a length ≥ 100 mm, wall thickness ≤ 0.8 mm, form and position accuracy ≤ 0.02 mm, and dimensional accuracy ≤ 0.03 mm. This method enables precision machining of ultra-thin-walled, high-precision beryllium tube parts, meeting the high-precision requirements of ultra-thin-walled beryllium tubes and achieving an overall total leakage rate of ≤ 0.5~2.5×10⁻¹¹ Pa. 3 / s, ultimate vacuum degree: ≤3~8×10-8Pa, required for strict environmental applications.

[0054] like Figure 1 As shown, the outer surface of the target ultrathin-walled beryllium tube includes two first outer circular surfaces 1, two arc transition surfaces 2, and a second outer circular surface 3; each end of the second outer circular surface 3 is connected to an arc transition surface 2, and the other end of each arc transition surface 2 is connected to a first outer circular surface 1; multiple reinforcing ribs 4 with equal intervals are provided on the second outer circular surface 3.

[0055] Specifically, the target ultrathin-walled beryllium tube has a wall thickness of ≤1.6mm on its first outer surface 1 and ≤0.8mm on its second outer surface 3. The target ultrathin-walled beryllium tube has a total of 6 reinforcing ribs 4, and the thickness of each reinforcing rib 4 is ≤0.8mm (e.g., ...). Figure 2 (As shown).

[0056] This embodiment proposes a precision machining method for ultra-thin-walled beryllium tube parts. The overall machining process is as follows: rough turning of the first outer cylindrical surface and inner hole → first aging treatment → semi-finish turning of the first outer cylindrical surface → semi-finish milling of the second outer cylindrical surface → second aging treatment → finish milling of the second outer cylindrical surface and arc transition surface → finish turning of the inner hole and end face → finish turning of the first outer cylindrical surface → chemical milling.

[0057] The specific processing method includes the following steps:

[0058] Step S1: The pre-treated beryllium tube is assembled on two first fixtures using a double-center clamping method. The clearance between the two first fixtures and the beryllium tube is ≤0.05mm, and the perpendicularity between the two first fixtures and the outer circle of the beryllium tube is ≤0.05mm. Then, the first outer circle and inner hole of the beryllium tube are rough machined.

[0059] Preferably, when rough machining the inner bore of the beryllium tube, a copper claw with an inner diameter equal to the outer diameter of the beryllium tube is used to fix the beryllium tube, so that the clamping force is evenly distributed on the surface of the beryllium tube, changing the line contact to a complete surface contact, increasing the contact area, reducing the clamping force per unit area, and thus avoiding clamping deformation and cracking of the beryllium tube during the rough machining process.

[0060] In this embodiment, a double-center clamping method is used to assemble the pre-treated beryllium tube onto two first toolings to avoid deformation caused by directly clamping the beryllium tube, while ensuring that the two end faces of the beryllium tube are perpendicular to the outer cylindrical surface when rough machining the first outer cylindrical surface.

[0061] Among them, such as Figure 3 As shown, the first tooling 5 is an end cap with a central hole. The structure of the beryllium tube assembled on the two first tooling 5 is as follows. Figure 4 As shown.

[0062] Preferably, the first tooling 5 is provided with multiple equally spaced water channels 18 on the outer circular surface and end face of the beryllium tube inner bore surface. These channels are used for the flow of adhesive when the beryllium tube is bonded to the first tooling to ensure a firm bond between the beryllium tube and the first tooling. They are also used for the flow of adhesive remover when the beryllium tube is separated from the tooling to ensure that the beryllium tube and the first tooling can be easily separated without damage to each other.

[0063] Step S2: Remove the first tooling and perform the first aging treatment on the beryllium tube that has been rough-machined on the first outer cylindrical surface and inner hole.

[0064] Preferably, the beryllium tube after rough machining of the first outer cylindrical surface and inner hole is subjected to multiple first aging treatments to fully release the internal stress and machining stress of the beryllium tube parts, thereby avoiding deformation of the beryllium tube parts caused by internal stress.

[0065] Step S3: Use the first tooling and the second tooling to fix the beryllium tube after the first aging treatment. The outer diameter runout of the fixed beryllium tube is ≤0.05mm. Then, the first outer diameter surface of the beryllium tube is semi-finished.

[0066] Among them, such as Figure 5 As shown, the second tooling 6 is a mandrel with a central shaft hole. One end of the mandrel is provided with a clamping platform 7 protruding from the outer periphery of the mandrel. The side of the clamping platform 7 near the other end of the mandrel is provided with a first 60° conical surface 8. The other end of the mandrel is provided with a long step 9. An external thread 10 is provided at a position connected to the long step 9 and away from the end face of the mandrel.

[0067] Step S4: The beryllium tube, which has been semi-finish-machined on the first outer cylindrical surface, is semi-finish-milled on the second outer cylindrical surface to form a plurality of equally spaced reinforcing ribs on the second outer cylindrical surface of the beryllium tube.

[0068] Step S5: Remove the first and second tooling, and perform a second aging treatment on the beryllium tube that has been semi-finish milled on the second outer cylindrical surface.

[0069] Preferably, the beryllium tube with the second outer cylindrical surface semi-finish milled is subjected to multiple second aging treatments to fully release the internal stress and processing stress of the beryllium tube part, thereby avoiding deformation of the beryllium tube part caused by internal stress.

[0070] Step S6: Use the first tooling and the second tooling to fix the beryllium tube after the second aging treatment. The outer diameter runout of the fixed beryllium tube is ≤0.03mm. Then, perform precision milling on the second outer diameter surface and the arc transition surface of the beryllium tube after the second aging treatment.

[0071] Preferably, the second outer circular surface 3 is first machined layer by layer and angle by angle to the preset size to ensure symmetry accuracy ≤0.02mm. Then, a ball end mill with Φ6mm-Φ10mm is used to complete the machining of the 6 reinforcing ribs at each angle.

[0072] Step S7: The third tooling is fitted onto the outer periphery of the beryllium tube fixed by the first and second toolings and bonded together. Wax is injected into the gap between the third tooling and the beryllium tube through the wax injection port of the third tooling. After the wax solidifies, the first and second toolings are removed to obtain the beryllium tube fixed by the third tooling. Then, the inner hole and end face of the beryllium tube are precision machined.

[0073] The third tooling 11 is a cylindrical ring without clamping force. The inner surfaces of both ends of the cylindrical ring are provided with steps that protrude from the inner surface of the cylindrical ring to form stepped inner holes 12. The steps are provided with multiple equally spaced first grooves 13. The depth of each first groove 13 is less than the height of the step. The side of the cylindrical ring is provided with multiple wax injection ports 14 that penetrate the side of the cylindrical ring. The clearance between the inner surface of the cylindrical ring and the beryllium tube is ≥0.05mm. The diameter of the stepped inner hole 12 is equal to the outer diameter of the beryllium tube.

[0074] In this embodiment, after the third tooling is fitted onto the outer periphery of the beryllium tube fixed by the first and second toolings, the first groove serves as a channel for adhesive. Adhesive is poured into the first groove to bond and fix the third tooling and the beryllium tube together. Preferably, the depth of the first groove is 3mm, and the height of the step is 5mm.

[0075] Step S8: Remove the third tooling, then insert the fourth tooling into the inner hole of the beryllium tube, which has been precision-machined in both the inner and end faces. The clearance between the fourth tooling and the beryllium tube is ≤0.05mm. Inject wax into the gap between the fourth tooling and the beryllium tube through one end of the second groove of the fourth tooling. After the wax solidifies, insert one end of the long step of the second tooling into the central shaft hole of the fourth tooling from one end of the 60° tapered hole of the fourth tooling. Then, use the first tooling to fix the other end of the beryllium tube, thus obtaining a beryllium tube fixed by the first, second, and fourth toolings. Finally, precision machine the first outer cylindrical surface of the beryllium tube.

[0076] The fourth tooling 15 is a cylinder with a central shaft hole. The inner surface of one end of the fourth tooling is provided with a second 60° conical surface 16 that matches the first 60° conical surface to form a 60° conical hole. The outer periphery of the fourth tooling is provided with a plurality of equally spaced second grooves 17. The depth of each second groove 17 is less than half the difference between the outer diameter and the inner diameter of the fourth tooling.

[0077] In this embodiment, the first 60° conical surface and the second 60° conical surface are perfectly matched, which can realize the automatic centering of the second tooling and the fourth tooling.

[0078] Step S9: Remove the first tooling, the second tooling and the fourth tooling, and perform chemical milling on the beryllium tube that has been precision machined on the first outer cylindrical surface to remove microcracks on the surface of the beryllium tube.

[0079] In some embodiments, the process parameters for rough machining the first outer cylindrical surface of the beryllium tube in step S1 are as follows:

[0080] The tool tip radius is R0.1mm~R0.3mm, the depth of cut is 0.05~0.2mm, the rotation speed is 200~500r / min, the feed rate is 0.01~0.03mm / r, and the machining allowance is 0.1~0.3mm.

[0081] In some embodiments, the process parameters for rough machining the inner bore of the beryllium tube in step S1 are as follows:

[0082] The tool tip radius is R0.1mm~R0.3mm, the depth of cut is 0.05~0.2mm, the spindle speed is 200~500r / min, the feed rate is 0.01~0.03mm / r, and the machining allowance is 0.05~0.15mm.

[0083] In some embodiments, the process parameters for semi-finish machining the first outer cylindrical surface of the beryllium tube in step S3 are as follows:

[0084] The tool tip radius is R0.1mm~R0.2mm, the depth of cut is 0.05~0.15mm, the spindle speed is 200~300r / min, the feed rate is 0.01~0.03mm / r, and the machining allowance is 0.05~0.2mm.

[0085] In some embodiments, the process parameters for semi-finish milling the second outer surface of the beryllium tube after semi-finish turning the first outer surface in step S4 are as follows:

[0086] The cutting depth is 0.05-0.15 mm, the rotation speed is 500-800 r / min, the feed rate is 100-300 mm / min, and the machining is carried out layer by layer until the reserved machining allowance is 0.1-0.3 mm.

[0087] In some embodiments, the process parameters for precision milling the second outer cylindrical surface and the arc transition surface of the beryllium tube after the second aging treatment in step S6 are as follows:

[0088] The cutting depth is 0.05–0.1 mm, the rotation speed is 600–1500 r / min, and the feed rate is 50–200 mm / min.

[0089] In some embodiments, the process parameters for precision machining the inner bore and end face of the beryllium tube in step S7 are as follows:

[0090] The tool tip radius is ≤R0.1mm, the cutting depth is 0.05~0.1mm, the rotation speed is 600~1500r / min, and the feed rate is 50~200mm / min.

[0091] In some embodiments, the process parameters for precision machining the first outer cylindrical surface of the beryllium tube in step S8 are as follows:

[0092] The tool tip radius is ≤R0.1mm, the cutting depth is 0.05~0.1mm, the rotation speed is 500~1000r / min, and the feed rate is 50~200mm / min.

[0093] In some embodiments, in step S9, the beryllium tube with the first outer cylindrical surface precision machined is subjected to chemical milling for 1-3 minutes.

[0094] In summary, the solution proposed in this invention has the following technical effects:

[0095] This invention avoids surface cracking, fissures, and deformation of ultra-thin-walled beryllium tubes by designing specialized tooling and processing the outer circumference of the beryllium tube in sections.

[0096] Furthermore, the ultrathin-walled beryllium tubes obtained using the method of this invention have a wall thickness ≤0.8mm, a form and position accuracy ≤0.02mm, and a dimensional accuracy ≤0.03mm, meeting the high-precision requirements of ultrathin-walled beryllium tubes and achieving an overall total leakage rate ≤0.5~2.5×10⁻¹¹ Pa. 3 / s, for product applications in harsh environments with an ultimate vacuum degree ≤3~8×10-8Pa.

[0097] Please note that the technical features of the above embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments have been described. However, as long as the combination of these technical features does not contradict each other, it should be considered within the scope of this specification. The above embodiments only illustrate several implementation methods of this application, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent. It should be pointed out that for those skilled in the art, several modifications and improvements can be made without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A method for precision machining of ultra-thin-walled beryllium tube parts, characterized in that, The outer surface of the beryllium tube includes two first outer surfaces, two arc transition surfaces, and one second outer surface; each end of the second outer surface is connected to an arc transition surface, and the other end of each arc transition surface is connected to a first outer surface; multiple reinforcing ribs with equal spacing are provided on the second outer surface. The method includes the following steps: Step S1: The pre-treated beryllium tube is assembled on two first fixtures using a double-center clamping method. The clearance between the two first fixtures and the beryllium tube is ≤0.05mm, and the perpendicularity between the two first fixtures and the outer circle of the beryllium tube is ≤0.05mm. Then, the beryllium tube is rough machined on the first outer circle surface and the inner hole. The first tooling is an end cap with a central hole; Step S2: Remove the first tooling and perform the first aging treatment on the beryllium tube that has been rough-machined on the first outer cylindrical surface and inner hole; Step S3: Use the first tooling and the second tooling to fix the beryllium tube after the first aging treatment. The outer diameter runout of the fixed beryllium tube is ≤0.05mm. Then, the first outer diameter surface of the beryllium tube is semi-finish machined. The second tooling is a mandrel with a central shaft hole. One end of the mandrel is provided with a clamping platform protruding from the outer periphery of the mandrel. The side of the clamping platform near the other end of the mandrel is provided with a first 60° conical surface. The other end of the mandrel is provided with a long step, and an external thread is provided at a position connected to the long step and away from the end face of the mandrel. Step S4: The beryllium tube, which has been semi-finish-machined on the first outer cylindrical surface, is semi-finish-milled on the second outer cylindrical surface to form a plurality of equally spaced reinforcing ribs on the second outer cylindrical surface of the beryllium tube; Step S5: Remove the first and second tooling, and perform a second aging treatment on the beryllium tube that has been semi-finish milled on the second outer cylindrical surface; Step S6: Use the first tooling and the second tooling to fix the beryllium tube after the second aging treatment. The outer diameter runout of the fixed beryllium tube is ≤0.03mm. Then, perform precision milling on the second outer diameter surface and the arc transition surface of the beryllium tube after the second aging treatment. Step S7: The third tooling is fitted onto the outer periphery of the beryllium tube fixed by the first and second toolings and bonded together. Wax is injected into the gap between the third tooling and the beryllium tube through the wax injection port of the third tooling. After the wax solidifies, the first and second toolings are removed to obtain the beryllium tube fixed by the third tooling. Then, the inner hole and end face of the beryllium tube are precision machined. The third tooling is a cylindrical ring without clamping force. The inner surfaces of both ends of the cylindrical ring are provided with steps protruding from the inner surface of the cylindrical ring, forming stepped inner holes. Each step has multiple equally spaced first grooves, the depth of which is less than the height of the step. Multiple wax injection ports penetrating the side of the cylindrical ring are provided on its side. The clearance between the inner surface of the cylindrical ring and the beryllium tube is ≥0.05mm, and the diameter of the stepped inner hole is equal to the outer diameter of the beryllium tube. Step S8: Remove the third tooling, then insert the fourth tooling into the inner hole of the beryllium tube with its inner hole and end face precision machined. The clearance between the fourth tooling and the beryllium tube is ≤0.05mm. Inject wax into the gap between the fourth tooling and the beryllium tube through one end of the second groove of the fourth tooling. After the wax solidifies, insert one end of the long step of the second tooling into the central shaft hole of the fourth tooling from one end of the 60° tapered hole of the fourth tooling, and use the first tooling to fix the other end of the beryllium tube, thus obtaining a beryllium tube fixed by the first tooling, the second tooling and the fourth tooling. Then, precision machine the first outer cylindrical surface of the beryllium tube. The fourth tooling is a cylinder with a central shaft hole. The inner surface of one end of the fourth tooling is provided with a second 60° conical surface that matches the first 60° conical surface to form a 60° conical hole. The outer periphery of the fourth tooling is provided with a plurality of equally spaced second grooves. The depth of each second groove is less than half the difference between the outer diameter and the inner diameter of the fourth tooling. Step S9: Remove the first tooling, the second tooling and the fourth tooling, and perform chemical milling on the beryllium tube that has been precision machined on the first outer cylindrical surface.

2. The precision machining method for ultra-thin-walled beryllium tube parts according to claim 1, characterized in that, In step S1, the process parameters for rough machining the first outer cylindrical surface of the beryllium tube are as follows: The tool tip radius is R0.1mm~R0.3mm, the depth of cut is 0.05~0.2mm, the rotation speed is 200~500r / min, the feed rate is 0.01~0.03mm / r, and the machining allowance is 0.1~0.3mm.

3. The precision machining method for ultra-thin-walled beryllium tube parts according to claim 1, characterized in that, In step S1, the process parameters for rough machining the inner bore of the beryllium tube are as follows: The tool tip radius is R0.1mm~R0.3mm, the depth of cut is 0.05~0.2mm, the spindle speed is 200~500r / min, the feed rate is 0.01~0.03mm / r, and the machining allowance is 0.05~0.15mm.

4. The precision machining method for ultra-thin-walled beryllium tube parts according to claim 1, characterized in that, In step S3, the process parameters for semi-finish machining the first outer cylindrical surface of the beryllium tube are as follows: The tool tip radius is R0.1mm~R0.2mm, the depth of cut is 0.05~0.15mm, the spindle speed is 200~300r / min, the feed rate is 0.01~0.03mm / r, and the machining allowance is 0.05~0.2mm.

5. The precision machining method for ultra-thin-walled beryllium tube parts according to claim 1, characterized in that, In step S4, the process parameters for semi-finish milling the second outer surface of the beryllium tube, which has undergone semi-finish turning of the first outer surface, are as follows: The cutting depth is 0.05-0.15 mm, the rotation speed is 500-800 r / min, the feed rate is 100-300 mm / min, and the machining is carried out layer by layer until the reserved machining allowance is 0.1-0.3 mm.

6. The precision machining method for ultra-thin-walled beryllium tube parts according to claim 1, characterized in that, In step S6, the process parameters for precision milling the second outer cylindrical surface and the arc transition surface of the beryllium tube after the second aging treatment are as follows: The cutting depth is 0.05–0.1 mm, the rotation speed is 600–1500 r / min, and the feed rate is 50–200 mm / min.

7. The precision machining method for ultra-thin-walled beryllium tube parts according to claim 1, characterized in that, In step S7, the process parameters for precision machining the inner bore and end face of the beryllium tube are as follows: The tool tip radius is ≤R0.1mm, the cutting depth is 0.05~0.1mm, the rotation speed is 600~1500r / min, and the feed rate is 50~200mm / min.

8. The precision machining method for ultra-thin-walled beryllium tube parts according to claim 1, characterized in that, In step S8, the process parameters for precision machining the first outer cylindrical surface of the beryllium tube are as follows: The tool tip radius is ≤R0.1mm, the cutting depth is 0.05~0.1mm, the rotation speed is 500~1000r / min, and the feed rate is 50~200mm / min.

9. The precision machining method for ultra-thin-walled beryllium tube parts according to claim 1, characterized in that, In step S9, the beryllium tube with the first outer cylindrical surface precision machined is subjected to chemical milling for 1-3 minutes.

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