A method of processing a metal piece with a closed flow channel

Abstract

A kind of processing method of metal piece with closed flow channel, the metal piece includes cylinder, and the peripheral wall of the metal piece is internally provided with circumferentially extending flow channel, it is characterized in that, sequentially include the following steps: step one, process annular cover;Step two, print out the blank in cylinder using additive manufacturing technology;Step three, annular groove is milled on the upper end surface of the blank, the mouth of the groove is upward, and at least partially compatible with annular cover;Step four, the annular cover obtained in step one is welded to the blank obtained in step three to close the mouth of the groove.The processing method of metal piece with closed flow channel involved in the present application makes the overall strength of the processed metal piece higher, and the process flow is shorter.

Description

Technical Field

[0001] This invention relates to the processing of metal parts, and more particularly to a method for processing metal parts with enclosed flow channels. Background Technology

[0002] Metal parts with enclosed flow channels are widely used in the automotive, petrochemical, military, and aerospace industries, such as automotive engines, petrochemical heat exchangers, and rocket engine expansion sections. Due to limitations in manufacturing processes, existing technologies typically involve separately machining the main structure and the enclosed flow channel component, and then mechanically connecting the enclosed flow channel component to the main structure.

[0003] Taking the rocket engine expansion section as an example, this metal component is a conical cylinder with a gas flow channel in the middle and a cooling water channel at the larger end. The traditional method for manufacturing the rocket engine expansion section is to first cast a conical cylinder, then constrain the machined gas flow channel and cooling water channel to the cylinder using clamps, which are then connected to the cylinder with bolts. Because the expansion section needs to withstand significant loads during rocket engine operation, and the gas flow channel and cooling water channel are prone to loosening between themselves and the cylinder, this can lead to inaccurate position monitoring results during rocket engine operation. Furthermore, drilling holes in the cylinder reduces the overall strength of the expansion section, affecting its pressure-bearing capacity. Moreover, this manufacturing method has a long process flow and high production costs.

[0004] Arc-wire additive manufacturing (AFM) is an advanced digital manufacturing technology that uses an electric arc or plasma arc as a heat source to melt metal wire. Under program or software control, it employs a layer-by-layer cladding principle to manufacture three-dimensional metal blanks that closely approximate the product's shape and size requirements from a line-surface-volume model. It boasts advantages such as low equipment cost, high material utilization, and high deposition efficiency. Therefore, AFM is suitable for the rapid prototyping of large metal components with complex structures. However, due to the process characteristics of AFM, which requires deposition on a substrate, it cannot achieve hollow structures. Therefore, for metal parts with flow channel structures, AFM alone is insufficient.

[0005] Furthermore, in arc filament additive manufacturing technology, the molten metal is formed in a free state. Due to the poor dimensional accuracy after solidification, auxiliary machining such as milling and turning is often required to ensure dimensional accuracy. For simple components, machining can be performed after the metal part is integrally formed; however, for some complex components, many areas cannot be machined once integrally formed. Therefore, machining areas that cannot be machined later and require high dimensional accuracy during the printing process can effectively improve the dimensional accuracy of the metal part. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a processing method for metal parts with closed flow channels, which is based on the above-mentioned technical status, so that the processed metal parts have higher overall strength, better pressure resistance, and shorter process flow.

[0007] The technical solution adopted by the present invention to solve the above-mentioned technical problem is as follows: a processing method for a metal part with a closed flow channel, wherein the metal part is cylindrical and the peripheral wall of the metal part is provided with a circumferentially extending flow channel, characterized in that it includes the following steps in sequence:

[0008] Step 1: Machining the ring-shaped cap;

[0009] Step 2: Use additive manufacturing technology to print a cylindrical blank;

[0010] Step 3: Mill an annular groove on the upper end face of the blank, with the opening of the groove facing upward and at least partially fitting the annular cover;

[0011] Step 4: Weld the annular cap obtained in Step 1 to the blank obtained in Step 3 to seal the opening of the groove.

[0012] To facilitate the processing of metal parts with multiple flow channels, the process also includes: Step 5: Using the upper end face of the single-flow-channel composite part obtained in Step 4 as a reference, Steps 1 to 4 are repeated sequentially until a multi-flow-channel composite part with a preset number of flow channels is obtained.

[0013] To facilitate the use of the metal parts or subsequent processing, the process also includes: Step 6, using the upper end face of the single-channel composite part obtained in Step 4 or the upper end face of the multi-channel composite part obtained in Step 5 as a reference, adding material upwards to a preset height.

[0014] To increase the cross-sectional area of ​​the flow channel, the cross-section of the flow channel is rectangular or trapezoidal, thereby allowing more fluid to flow through.

[0015] In order to provide sufficient wall thickness for the design of flow channels in certain parts of the metal part, the outer peripheral wall of the metal part is provided with an outwardly protruding part, and the flow channel is located inside the protrusion.

[0016] In order to make the annular cap and the blank fit together more tightly, the annular cap can be fitted into the opening of the groove.

[0017] Further design, in step one, the processing method of the annular cover is at least one of additive manufacturing, casting, and machining.

[0018] Laser welding is a highly efficient and precise welding method that uses a high-energy-density laser beam as a heat source. It offers advantages such as concentrated energy and a small heat-affected zone. By controlling the laser power and welding parameters, precise control of the weld penetration can be achieved, enabling single-sided welding with double-sided forming. Due to the superior forming quality of the back side of the laser weld, it is frequently used for welding enclosed structures such as rocket storage tanks and aircraft control wings. Therefore, in further design, the welding process in step four is laser welding.

[0019] To make the blank easier to form, the blank is processed on an additive substrate, and the composition of the metal part is the same as or similar to that of the additive substrate.

[0020] To ensure that the metal parts have good mechanical properties, the metal parts contain the following components in the following weight ratios, based on 100% weight: Cu: 5.3-5.8 wt%, Mn: 0.2-0.4 wt%, Ti: 0.02-0.15 wt%, Zr: 0.1-0.25 wt%, V: 0.05-0.15 wt%, Fe: ≤0.3 wt%, with the balance being Al.

[0021] Compared with the prior art, the advantages of the present invention are as follows: by first dividing the metal part into an annular cover and a blank for separate processing, then milling an annular groove with its opening facing upward on the upper end face of the blank, and finally welding the annular cover to the blank to close the opening of the groove, the advantages of rapid prototyping of complex metal components by additive and subtractive manufacturing are utilized, and the disadvantage of not being able to process hollow structures by partial welding of the metal component is improved, thereby improving the dimensional accuracy of the metal part, realizing the overall forming of the metal part with closed flow channels, making the processed metal part with closed flow channels have higher overall strength and better pressure resistance, and the process flow is shorter. Attached Figure Description

[0022] Figure 1 This is a flowchart of the metal part processing in an embodiment of the present invention;

[0023] Figure 2 This is a three-dimensional structural diagram of the first annular cover in an embodiment of the present invention;

[0024] Figure 3 This is a three-dimensional structural diagram of the second annular cover in an embodiment of the present invention;

[0025] Figure 4 This is a three-dimensional structural diagram of the first blank in an embodiment of the present invention;

[0026] Figure 5 for Figure 4 The first blank shown is a cross-sectional view;

[0027] Figure 6 for Figure 4The figure shows a three-dimensional structure of the first blank after the first groove has been milled.

[0028] Figure 7 for Figure 4 The cross-sectional view shown is of the first blank after the first groove has been milled.

[0029] Figure 8 This is a three-dimensional structural diagram of the single-channel composite in an embodiment of the present invention;

[0030] Figure 9 for Figure 8 Cross-sectional view of the single-channel complex shown;

[0031] Figure 10 for Figure 8 The single-channel composite shown is printed with a cross-sectional view after the second blank is produced.

[0032] Figure 11 for Figure 8 The cross-sectional view of the single-channel composite shown is obtained after printing the second blank and milling the second groove.

[0033] Figure 12 This is a three-dimensional structural diagram of the multi-channel composite in an embodiment of the present invention;

[0034] Figure 13 This is a cross-sectional view of the multi-channel composite in an embodiment of the present invention;

[0035] Figure 14 This is a three-dimensional structural diagram of the metal part in an embodiment of the present invention;

[0036] Figure 15 This is a cross-sectional view of the metal part in an embodiment of the present invention. Detailed Implementation

[0037] The embodiments of the present invention will be described in further detail below.

[0038] like Figures 1-15 The diagram shows the preferred embodiment of the invention.

[0039] In this embodiment, the metal component with a closed flow channel is the expansion section of a rocket engine. This metal component 100 is a conical cylinder with a smaller bottom and a larger top, and it extends axially. The lower diameter d of the metal component 100 is 330 mm, the upper diameter D is 860 mm, and the height h is 578 mm. The peripheral wall of the metal component 100 has a first protrusion 101 protruding outward in the middle. The distance h1 between the first protrusion 101 and the lower end of the metal component 100 is 286 mm. The interior of the first protrusion 101 has a closed gas flow channel 1010, and the cross-section of the gas flow channel 1010 is a rectangle with a length of 12 mm and a width of 5 mm. The peripheral wall of the metal part 100 has a second protrusion 102 protruding outward near its upper end surface. The distance h2 between the second protrusion 102 and the upper end surface of the metal part 100 is 3 mm. The interior of the second protrusion 102 has a closed cooling channel 1020. The cross-section of the cooling channel 1020 is trapezoidal with an upper base of 21 mm, a lower base of 29 mm, and a height of 24 mm. The term "closed channel" in this application refers to a channel whose cross-section is closed.

[0040] The metal part 100 uses ZCL2319C alloy wire (Fushun Donggong Metallurgical Materials Technology Co., Ltd., with a diameter of 1.2mm) as raw material. The chemical composition of the ZCL2319C alloy wire (by mass fraction) is: Cu: 5.62%, Mn: 0.28%, Ti: 0.17%, Zr: 0.18%, V: 0.12%, Fe: 0.11%, with the balance being Al.

[0041] The preparatory work for the metal part 100 with a closed flow channel in this embodiment before processing is as follows:

[0042] 1. Based on the model of the expanded section finished product, design an additive manufacturing model. In this additive manufacturing model, a 2mm machining allowance is reserved for the inner wall, a 2mm machining allowance is reserved for the outer wall, and a 5mm machining allowance is reserved for the upper and lower end faces.

[0043] 2. Plan the additive manufacturing path and the subtractive manufacturing path, and simulate them through computer simulation.

[0044] 3. Using 2319 board material with a composition similar to ZCL2319C as the additive manufacturing substrate, clean the substrate, clamp and position the substrate on the additive manufacturing equipment, and preheat the 2319 base plate.

[0045] The processing method of the metal part 100 with a closed flow channel in this embodiment includes the following steps in sequence:

[0046] Step 1: The first annular cover 21 and the second annular cover 22 are machined using machining technology. The first annular cover 21 includes an annular base 211 and two lugs 212 disposed opposite to each other on the outer annular side of the base. The dimensions of the base 211 are an outer diameter of 534 mm, an inner diameter of 524 mm, and a thickness of 4 mm. The dimensions of the lugs 212 are a length of 56 mm, a width of 17 mm, and a thickness of 4 mm. The dimensions of the second annular cover 22 are an outer diameter of 850 mm, an inner diameter of 808 mm, and a thickness of 4 mm. The aforementioned "outer diameter" and "inner diameter" are both diameters.

[0047] Step 2: After grinding and preheating the additive substrate, ZCL2319C alloy wire is selected as the raw material. Using additive manufacturing technology, a first blank 11 in the shape of a cone and extending along the axial direction is printed on the 2319 additive substrate. The height of the first blank 11 is 286mm (that is, the distance h1 between the first protrusion 101 and the lower end of the metal part 100). The arc wire additive manufacturing parameters are: wire feeding speed 6-7m / min, welding speed 8-10mm / s, and printing path: spiral growth from the small end upwards.

[0048] Step 3: Remove the additive manufacturing equipment and use a CNC milling machine with a milling cutter of R2.5 to mill a ring-shaped first groove 111 with its opening facing upward on the upper end face of the first blank 11. The first groove 111 has a cross-sectional length of 16mm and a width of 5mm.

[0049] Step 4: The first annular cover 21 is fitted into the opening of the first groove 111, and the first annular cover 21 is welded to the first blank 11 using laser welding technology, so that the first groove 111 and the first annular cover 21 form a closed gas flow channel 1010. The laser welding path is: annular welding along the butt joint gap, and the laser welding parameters are: laser power 3KW, welding speed 30mm / s.

[0050] Step 5: Using the upper end face of the single-channel composite part 10 processed in Step 4 as a reference, continue to print the second blank 12. The height of the second blank 12 is 289mm (that is, the height h minus the distance h1 between the first protrusion 101 and the lower end of the metal part 100, and the distance h2 between the second protrusion 102 and the upper end face of the metal part 100). The arc wire additive manufacturing parameters are: wire feeding speed 6-7m / min, welding speed 8-10mm / s, and the printing path is: spiral growth from the small end upwards.

[0051] Step 6: Remove the additive manufacturing equipment and use a CNC milling machine with a milling cutter of R2.5 to mill a ring-shaped second groove 121 with its opening facing upward on the upper end face of the second blank 12. The cross-section of the second groove 121 is trapezoidal, with the upper base of the trapezoid being 21mm, the lower base being 29mm, and the height being 28mm.

[0052] Step 7: The second annular cover 22 is fitted into the opening of the second groove 121, and the second annular cover 22 is welded to the second blank 12 using laser welding technology, so that the second groove 121 and the second annular cover 22 form a closed cooling channel 1020. The laser welding path is: annular welding along the butt joint gap, and the laser welding parameters are: laser power 3KW, welding speed 30mm / s.

[0053] Step 8: Using the upper surface of the multi-channel composite part 20 processed in Step 7 as a reference, continue to add material upwards by 3mm (i.e., the distance h2 between the second protrusion 102 and the upper surface of the metal part 100), so that the metal part 100 reaches the preset height.

[0054] Step 9: Use a CNC milling machine to machine a reference on the upper surface of the metal part 100 for subsequent processing.

[0055] Finished product testing

[0056] The metal part 100 processed by the method in this embodiment was subjected to X-ray inspection and tensile strength testing. The gas flow channel 1010 and cooling flow channel 1020 were subjected to water pressure and airtightness tests. The relevant test reference standards are as follows:

[0057] X-ray inspection: 100% of the products shall undergo X-ray inspection. X-ray flaw detection shall be carried out in accordance with Article 5 of NB / T47013.2-2015 "Non-destructive Inspection of Pressure Equipment", and the evaluation shall be carried out in accordance with Article 6.2. The internal quality grade of the product shall not be lower than the relevant requirements of weld quality Grade II.

[0058] Tensile strength test: The furnace-fired specimens were subjected to room temperature tensile test in accordance with GB / T228.1-2010. The tensile strength was required to be ≥410 MPa, yield strength ≥290 MPa, elongation after fracture ≥8%, and hardness HBS ≥100.

[0059] Water pressure test: Perform a water pressure test on the closed flow channel at a pressure of 6 MPa for a holding time of 1 minute.

[0060] Air tightness test: Perform a water pressure test on the closed flow channel at a pressure of 1 MPa for 10 minutes.

[0061] The test results are as follows:

[0062] The internal quality of this metal part is higher than Grade II of the weld quality. The room temperature tensile strength of metal part 100 is 440 MPa, the yield strength is 310 MPa, the elongation after fracture is 12%, and the hardness is HBS112. The gas flow channel 1010 and cooling flow channel 1020 of metal part 100 were held at 6 MPa for 1 minute without pressure release. The airtightness test of the gas flow channel 1010 and cooling flow channel 1020 of metal part 100 was conducted at 1 MPa for 10 minutes without pressure release.

Claims

1. A method of processing a metal member with a closed flow channel, said metal member (100) comprising a cylindrical shape, and a circumferentially extending flow channel being provided inside a peripheral wall of said metal member (100), characterized in that, The steps are as follows: Step 1: Machining the ring-shaped cap; Step 2: Use additive manufacturing technology to print a cylindrical blank; Step 3: Mill an annular groove on the upper end face of the blank, with the opening of the groove facing upward and at least partially fitting the annular cover; Step 4: Weld the annular cap obtained in Step 1 to the blank obtained in Step 3 to seal the opening of the groove; Step 5: Using the upper end face of the single-channel composite part (10) obtained in Step 4 as a reference, repeat Step 1 to Step 4 in sequence until a multi-channel composite part (20) with a preset number of channels is obtained. Step 6: Using the upper end face of the single-channel composite (10) obtained in Step 4 or the upper end face of the multi-channel composite (20) obtained in Step 5 as a reference, add material upwards to the preset height.

2. The method of claim 1 wherein, The cross-section of the flow channel is rectangular or trapezoidal.

3. The method of claim 1 wherein, The outer peripheral wall of the metal part (100) is provided with an outwardly protruding part, and the flow channel is located inside the protruding part.

4. The method of claim 1 wherein, The annular cap can be fitted into the opening of the groove.

5. The method of claim 1 wherein, In step one, the processing technology of the annular cover is at least one of additive manufacturing, casting, and machining.

6. The method of claim 1 wherein, The welding process in step four is laser welding.

7. The processing method according to any one of claims 1 to 6, characterized in that, The blank is processed on an additive substrate, and the composition of the metal part (100) is the same as or similar to that of the additive substrate.

8. The method of any one of claims 1-6, wherein, The metal part (100) comprises the following components in the following weight ratios, based on 100% by weight: Cu: 5.3-5.8 wt%, Mn: 0.2-0.4 wt%, Ti: 0.02-0.15 wt%, Zr: 0.1-0.25 wt%, V: 0.05-0.15 wt%, Fe: ≤0.3 wt%, with the balance being Al.

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