Method for machining half-and-half axial flow casing through forge piece

Abstract

The invention discloses a machining method for a forging half-and-half axial flow casing. The machining method comprises the following steps that S1, a cylindrical forging blank is obtained through forging; s2, rough machining is conducted on the forge piece blank; s3, the outer contour of the large end and the outer contour of the small end are sequentially machined to the design size through eccentric milling, the allowance of 1-2 mm is reserved on the boss end face of the forged piece blank, and the allowance of 1-2 mm is reserved on the longitudinal binding face of the forged piece blank; s4, the forging blank is subjected to heat treatment; s5, a runner and an inner groove of the forging blank are subjected to rough machining, the allowance of 1-2 mm is reserved for the runner, and the allowance of 1-2 mm is reserved for the inner groove; s6, the forging blank is linearly cut into a left half casing and a right half casing; s7, the longitudinal binding face is machined to the designed size, then the end face of the boss, the flow channel and the inner groove are machined to the designed size, and the forged half-and-half axial flow case is obtained; compared with the prior art, deformation is small, quality is stable and controllable, the design pattern requirement can be met, the machining period is short, and the new machine development period is greatly shortened.

Description

Technical Field

[0001] The invention relates to the technical field of aero-engines, and in particular to a method for processing a semi-axial flow casing using a forging. Background Art

[0002] In the compressor of small and medium-sized aircraft engines, the axial flow casing is its core component and plays a decisive role in the performance parameters of the aircraft engine. The axial flow casing is a thin-walled part with poor rigidity and easy deformation. Since the rotor blades and stator blades on the compressor are distributed alternately in sequence, when the axial flow casing adopts a half-and-half structure, the compressor rotor blade parts can be assembled separately as a component, and the compressor stator blades can be assembled separately as a component. By merging the half-open axial flow casing, the rotor assembly and the stator assembly can be assembled together, and the rotor blades and the stator blades can be distributed alternately in sequence. The non-adjustable stator blades can also be designed as a non-integral ring structure to realize the installation of all axial flow stage stator blades on one casing, and after the aircraft engine is assembled, the half-axial flow casing and the stator blades assembled on the half-axial flow casing can be opened to visually check the gap between the rotor and the stator blades to ensure the safety of the aircraft engine. This structural layout is simple to assemble, compact in space, and highly reliable, and is widely used in small and medium-sized aircraft engines.

[0003] At present, the axial flow casing blanks produced in batches are all castings, which have less machining allowance and have a relatively stable processing technology. However, due to the complex structure of the axial flow casing, the cycle from casting blanks to stable production of qualified blanks is too long, about 6 months to 1.5 years; therefore, in the pre-research stage of the engine, in order to shorten the development cycle, forging blanks are often used to process the finished axial flow casing, so as to test the feasibility of the engine design in advance. Compared with castings, forgings have a short production cycle, but a larger machining allowance, greater deformation of parts during roughing, and higher machining difficulty. In addition, forgings are cylindrical. If the outer boss and inner runner are processed in a conventional circular state during actual processing, the stress release deformation will be large after the parts are cut into two halves of the casing, and the flatness of the fitting surface of the two halves of the casing is poor and cannot meet the requirements of part assembly and sealing (the design requires flatness to be no more than 0.03mm). The longitudinal fitting surface needs to be further fine-machined. After the longitudinal fitting surface is fine-machined, the boss of the assembled two halves of the casing has a large deviation from the design theoretical position and cannot meet the design requirements. Therefore, how to reasonably arrange the process to ensure that after the outer contour of the part is processed, the part cutting and reassembly can ensure that the deviation between the outer boss of the part and the design theoretical position is minimal, and then ensure the size and position requirements of the subsequent boss is a difficult problem that needs to be overcome. Summary of the invention

[0004] The invention provides a method for processing a forged semi-axial flow casing, so as to solve the technical problems of long processing cycle or great processing difficulty of the existing semi-axial flow casing.

[0005] According to one aspect of the present invention, there is provided a method for processing a forged semi-axial flow casing, comprising the following steps: S1, forging to obtain a cylindrical forging blank; S2, rough machining the forging blank; S3, using eccentric milling to sequentially machine the outer contour of the large end and the outer contour of the small end to the designed size, wherein a 1mm-2mm margin is reserved for the boss end face of the forging blank, and a 1mm-2mm margin is reserved for the longitudinal fitting surface of the forging blank; S4, heat treating the forging blank; S5, rough machining the flow channel and the inner groove of the forging blank, wherein a 1mm-2mm margin is reserved for the flow channel, and a 1mm-2mm margin is reserved for the inner groove; S6, linearly cutting the forging blank into a left and a right half casing; S7, machining the longitudinal fitting surface to the designed size, and then machining the boss end face, the flow channel and the inner groove to the designed size to obtain the forged semi-axial flow casing.

[0006] As a further improvement of the above technical solution:

[0007] Furthermore, step S3 specifically includes the following steps: S31, supporting the large end of the forging blank and pressing the large end mounting edge, and then using eccentric milling to process the outer contour of the small end to the designed size, and during the processing, the boss end face on the forging blank close to the small end is reserved with a 1mm-2mm margin, and the longitudinal fitting surface on the forging blank close to the small end is reserved with a 1mm-2mm margin; S32, supporting the small end of the forging blank and pressing the small end mounting edge, and then using eccentric milling to process the outer contour of the large end to the designed size, and during the processing, the boss end face on the forging blank close to the large end is reserved with a 1mm-2mm margin, and the longitudinal fitting surface on the forging blank close to the large end is reserved with a 1mm-2mm margin.

[0008] Furthermore, between step S31 and step S32, there is also a step of marking the outer contour of the small end of the forging blank.

[0009] Furthermore, step S2 specifically includes the following steps: S21, clamping the forging blank to pre-roughen the small end of the forging blank, and then removing the inner hole, end face and outer circle of the forging blank close to the small end by rotating the forging blank to the maximum contour, and leaving at least 3mm margin; S22, supporting the small end of the forging blank and pressing the small end mounting edge to pre-roughen the large end of the forging blank, and then removing the inner hole, end face and outer circle of the forging blank close to the large end by rotating the forging blank to the maximum contour, and leaving at least 3mm margin.

[0010] Furthermore, in step S3, the specific steps of eccentric milling are as follows: first use a Φ16mm milling cutter for rough machining and reserve a 0.5mm-1mm margin, then use a Φ8mm milling cutter for fine machining, and finally use a Φ4mm and Φ2mm milling cutter to clean the corners of the part's outer contour or the boss connection.

[0011] Furthermore, in step S3, the processing parameters of various types of milling cutters are as follows: Φ16 milling cutter: linear speed is 80m / s-90m / s, feed rate is 200mm / min-230mm / min; Φ8 milling cutter: linear speed is 40m / s-50m / s, feed rate is 110mm / min-120mm / min; Φ4 milling cutter: linear speed is 30m / s-40m / s, feed rate is 50mm / min-60mm / min; Φ2 milling cutter: linear speed is 15m / s-20m / s, feed rate is 20mm / min-30mm / min.

[0012] Furthermore, in step S7, the specific steps of first processing the longitudinal fitting surface to the designed size are as follows: S71, support the large end of the forging blank on a milling machine, and press the back side of the large end mounting edge, align the diagonal surface runout of the forging blank to be less than 0.03mm, then provide auxiliary support to the small end, and press the small end, and finally mill the longitudinal fitting surface, and reserve a 0.05mm-0.1mm margin; S72, support the large end of the forging blank on a grinding machine, and press the back side of the large end mounting edge, align the diagonal surface runout of the forging blank to be less than 0.03mmm, then provide auxiliary support to the small end, and press the large end, and finally grind the longitudinal fitting surface, and ensure that the flatness of the longitudinal fitting surface is less than 0.02mm.

[0013] Furthermore, in steps S71 and S72, when the small end and the large end are compressed, a micrometer is used to check the change before and after compression, and ensure that the change before and after is less than 0.005 mm.

[0014] Furthermore, between step S1 and step S2, there is also a step of marking the forging blank.

[0015] Furthermore, between step S2 and step S3, there is also a step of re-marking the forging blank.

[0016] The present invention has the following beneficial effects:

[0017] The forging method for processing a semi-axial flow casing of the present invention first obtains a cylindrical forging blank by forging, and then roughly processes the forging blank, and then uses eccentric milling to sequentially process the outer contour of the large end and the outer contour of the small end to the designed size, so as to reserve a 1mm-2mm margin for the longitudinal fitting surface after the subsequent forging blank is cut, and then after the subsequent longitudinal fitting surface margin is removed, it is ensured that the boss has a minimum deviation from the designed theoretical position, and at the same time, a 1mm-2mm margin is reserved for the boss end face to eliminate the deviation in the subsequent processing steps; after the outer contour of the forging blank is processed in place, the forging blank is heat treated to eliminate the larger cutting stress caused by removing more margins; the outer contour has the largest processing margin and the largest processing deformation, therefore, the outer contour is processed first, and then the flow channel and the inner groove of the forging blank are roughly processed to process the outer contour When cutting the forging blank into the left and right half casings, ensure that the runner and the inner groove have sufficient margin, the parts have good rigidity, and can reduce processing deformation; reserve 1mm-2mm margin for the runner and 1mm-2mm margin for the inner groove, so that when the forging blank is subsequently wire-cut into the left and right half casings, the wire cutting amount can be reduced as much as possible while ensuring that the forging blank has sufficient rigidity, avoiding excessive stress release after the forging blank is cut into two halves, thereby affecting the processing of the longitudinal fitting surface and the position of the boss; finally, the longitudinal fitting surface is processed to the design size, and then the boss end face, runner and inner groove are processed to the design size to obtain the forged half-axial flow casing; the forged half-axial flow casing processed by this scheme has smaller deformation, stable and controllable quality, can meet the requirements of the design drawings, has a short processing cycle, greatly shortens the development cycle of new machines, has strong practicality, and is suitable for wide promotion and application.

[0018] In addition to the above-described purposes, features and advantages, the present invention has other purposes, features and advantages. The present invention will be further described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The drawings constituting a part of this application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0020] Figure 1 It is a flowchart of the steps of a method for processing a semi-axial flow casing with a forging according to a preferred embodiment of the present invention;

[0021] Figure 2 It is a structural schematic diagram of a forging blank in step S1 of a method for processing a semi-axial flow casing with a forging according to a preferred embodiment of the present invention;

[0022] Figure 3 It is a structural schematic diagram of a forging blank in step S21 of a method for processing a semi-axial flow casing with a forging according to a preferred embodiment of the present invention;

[0023] Figure 4 It is a structural schematic diagram of a forging blank in step S22 of a method for processing a semi-axial flow casing with a forging according to a preferred embodiment of the present invention;

[0024] Figure 5 It is a structural schematic diagram of a forging blank in step S3 of a method for processing a semi-axial flow casing with a forging according to a preferred embodiment of the present invention;

[0025] Figure 6 It is a structural schematic diagram of a forging blank in step S31 of a method for processing a semi-axial flow casing with a forging according to a preferred embodiment of the present invention;

[0026] Figure 7 It is a structural schematic diagram of a forging blank in step S32 of a method for processing a semi-axial flow casing with a forging according to a preferred embodiment of the present invention;

[0027] Figure 8 It is a structural schematic diagram of a forging blank in step S5 of a method for processing a semi-axial flow casing with a forging according to a preferred embodiment of the present invention;

[0028] Fig. 9 It is a structural schematic diagram of a forging blank in step S6 of a method for processing a semi-axial flow casing with a forging according to a preferred embodiment of the present invention;

[0029] Fig.10 It is a schematic structural diagram of a forging blank in step S71 of a method for processing a semi-axial flow casing with forgings according to a preferred embodiment of the present invention. DETAILED DESCRIPTION

[0030] The embodiments of the present invention are described in detail below with reference to the accompanying drawings. However, the present invention can be implemented in many different ways as defined and covered below.

[0031] like Figure 1-Figure 10 As shown, the processing method of the forging pair semi-axial flow casing of the present embodiment includes the following steps: S1, forging to obtain a cylindrical forging blank; S2, rough machining the forging blank; S3, using eccentric milling to sequentially machine the outer contour of the large end and the outer contour of the small end to the design size, wherein the boss end face of the forging blank reserves a 1mm-2mm margin, and the longitudinal fitting surface of the forging blank reserves a 1mm-2mm margin; S4, heat treating the forging blank; S5, rough machining the flow channel and the inner groove of the forging blank, wherein the flow channel reserves a 1mm-2mm margin, and the inner groove reserves a 1mm-2mm margin; S6, linearly cutting the forging blank into left and right half casings; S7, first machining the longitudinal fitting surface to the design size, and then machining the boss end face, the flow channel and the inner groove to the design size to obtain the forging pair semi-axial flow casing.

[0032] Specifically, the forging method of the present invention for processing a semi-axial flow casing is to first obtain a cylindrical forging blank by forging, and then rough-process the forging blank, and then use eccentric milling to sequentially process the outer contour of the large end and the outer contour of the small end to the designed size, so as to reserve a 1mm-2mm margin for the longitudinal fitting surface after the subsequent forging blank is cut, and then after the subsequent longitudinal fitting surface margin is removed, it is ensured that the boss has a minimum deviation from the designed theoretical position, and at the same time, a 1mm-2mm margin is reserved for the boss end face to eliminate the deviation in subsequent processing steps; after the outer contour of the forging blank is processed in place, the forging blank is heat treated to eliminate the larger cutting stress caused by removing more margin; the outer contour has the largest processing margin and the largest processing deformation, therefore, the outer contour is processed first, and then the flow channel and inner groove of the forging blank are rough-processed to process the outer contour. When contouring, ensure that the runner and the inner groove have sufficient margin, the rigidity of the parts is good, and the processing deformation can be reduced; a 1mm-2mm margin is reserved for the runner, and a 1mm-2mm margin is reserved for the inner groove, so that when the forging blank is subsequently wire-cut into the left and right half casings, the wire cutting amount can be reduced as much as possible while ensuring that the forging blank has sufficient rigidity, and avoid excessive stress release after the forging blank is cut into two halves, thereby affecting the processing of the longitudinal fitting surface and the position of the boss; finally, the longitudinal fitting surface is processed to the design size, and then the boss end face, runner and inner groove are processed to the design size to obtain the forged half-axial flow casing; compared with the existing technology, the forged half-axial flow casing processed by this scheme has smaller deformation, stable and controllable quality, can meet the requirements of the design drawings, has a short processing cycle, greatly shortens the development cycle of new machines, has strong practicality, and is suitable for wide promotion and application.

[0033] like Figure 5-Figure 7 As shown, in this embodiment, step S3 specifically includes the following steps: S31, supporting the large end of the forging blank and pressing the large end mounting edge, and then using eccentric milling to process the outer contour of the small end to the designed size, and in the process, the boss end face on the forging blank close to the small end is reserved with a 1mm-2mm margin, and the longitudinal fitting surface on the forging blank close to the small end is reserved with a 1mm-2mm margin; S32, supporting the small end of the forging blank and pressing the small end mounting edge, and then using eccentric milling to process the outer contour of the large end to the designed size, and in the process, the boss end face on the forging blank close to the large end is reserved with a 1mm-2mm margin, and the longitudinal fitting surface on the forging blank close to the large end is reserved with a 1mm-2mm margin. Specifically, the large end of the forging blank is clamped first to process the outer contour of the small end of the forging blank; then the small end of the forging blank is clamped to process the outer contour of the small end of the forging blank, and the processing accuracy is guaranteed by converting the processing reference.

[0034] In this embodiment, the step S31 and S32 further include the step of marking the outer contour of the small end of the forging blank. Specifically, after the outer contour of the small end of the forging blank is processed, the outer contour of the small end of the forging blank is marked to update the information and avoid confusion.

[0035] like Figure 3 and Figure 4 As shown, in this embodiment, step S2 specifically includes the following steps: S21, clamping the forging blank to pre-roughen the small end of the forging blank, and then using the maximum contour of the forging blank to rotate to remove the inner hole, end face and outer circle of the forging blank near the small end, and leaving at least 3mm margin; S22, supporting the small end of the forging blank and pressing the small end mounting edge to pre-roughen the large end of the forging blank, and then using the maximum contour of the forging blank to rotate to remove the inner hole, end face and outer circle of the forging blank near the large end, and leaving at least 3mm margin. Specifically, by pre-roughening the large end and the small end of the forging blank respectively, a processing benchmark is provided for subsequent processing, and the forging blank is rough-machined to leave at least 3mm margin to ensure smooth subsequent processing.

[0036] In this embodiment, in step S3, the specific steps of eccentric milling are as follows: first use a Φ16mm milling cutter for rough machining, and reserve a 0.5mm-1mm margin, then use a Φ8mm milling cutter for fine machining, and finally use a Φ4mm and Φ2mm milling cutter to clean the corners of the outer contour of the part or the boss connection. Specifically, first use a Φ16mm milling cutter to perform rough machining on the forging blank to improve machining efficiency, and reserve a 0.5mm-1mm margin for fine machining to avoid excessive deformation during rough machining, which will cause subsequent machining to fail, and then use a Φ8mm milling cutter for fine machining.

[0037] In this embodiment, in step S3, the processing parameters of various milling cutters are as follows: Φ16 milling cutter: linear speed is 80m / s-90m / s, feed rate is 200mm / min-230mm / min; Φ8 milling cutter: linear speed is 40m / s-50m / s, feed rate is 110mm / min-120mm / min; Φ4 milling cutter: linear speed is 30m / s-40m / s, feed rate is 50mm / min-60mm / min; Φ2 milling cutter: linear speed is 15m / s-20m / s, feed rate is 20mm / min-30mm / min. Specifically, during rough machining, the Φ16 milling cutter uses high linear speed and high feed rate to quickly remove the excess, and reduces the speed during fine machining and root cleaning to reduce cutting force, thereby reducing machining deformation.

[0038] like Fig.10As shown, in this embodiment, in step S7, the specific steps of first processing the longitudinal fitting surface to the designed size are as follows: S71, support the large end of the forging blank on a milling machine, and press the back side of the large end mounting edge, align the diagonal surface runout of the forging blank to be less than 0.03mm, then provide auxiliary support for the small end, and press the small end, and finally mill the longitudinal fitting surface, and reserve a 0.05mm-0.1mm margin; S72, support the large end of the forging blank on a grinding machine, and press the back side of the large end mounting edge, align the diagonal surface runout of the forging blank to be less than 0.03mmm, then provide auxiliary support for the small end, and press the large end, and finally grind the longitudinal fitting surface, and ensure that the flatness of the longitudinal fitting surface is less than 0.02mm. Specifically, when clamping the forging blank on the milling machine and the grinding machine, the runout of the diagonal surface of the forging blank is aligned to be less than 0.03mm, and the auxiliary support is adjusted to ensure that the small end mounting edge has reliable support, thereby ensuring that the forging blank is clamped reliably, thereby ensuring the processing quality during milling and grinding.

[0039] In this embodiment, in steps S71 and S72, when the small end and the large end are pressed, a micrometer is used to check the change before and after pressing, and ensure that the change before and after is less than 0.005 mm. Specifically, the change before and after pressing is checked by a micrometer to avoid processing and pressing deformation and ensure the uniformity of processing removal of excess.

[0040] In this embodiment, between step S1 and step S2, there is also a step of marking the forging blank. Specifically, by marking the forging blank, the new type of the workpiece is marked, the processing operation is guided, and the quality of the workpiece is ensured.

[0041] In this embodiment, between step S2 and step S3, the step of re-marking the forging blank is also included. Specifically, after the forging blank is roughly processed, the forging blank is re-marked to update the processing information.

[0042] In one embodiment, the specific processing steps of the forging of the semi-axial flow casing are as follows:

[0043] like Figure 2 As shown, a cylindrical forging blank is obtained by forging, and the forging blank is marked;

[0044] like Figure 3 As shown, the forging blank is clamped to pre-roughen the small end of the forging blank, and then the inner hole, end face and outer circle of the forging blank close to the small end are removed by rotating the forging blank with the maximum profile, and at least 3mm margin is reserved;

[0045] like Figure 4As shown, the small end of the forging blank is supported and the mounting edge of the small end is pressed to pre-roughen the large end of the forging blank, and then the inner hole, end face and outer circle of the forging blank close to the large end are removed with the maximum profile of the forging blank rotation, and at least 3mm margin is reserved;

[0046] Re-mark the forging blank;

[0047] like Figure 6 As shown, the large end of the forging blank is supported and the mounting edge of the large end is pressed, and then the outer contour of the small end is processed to the designed size by eccentric milling. In the process, a 1mm-2mm margin is reserved for the boss end face close to the small end of the forging blank, and a 1mm-2mm margin is reserved for the longitudinal fitting surface close to the small end of the forging blank;

[0048] Transfer the mark to the outer contour of the small end of the forging blank;

[0049] like Figure 7 As shown, the small end of the forging blank is supported and the mounting edge of the small end is pressed, and then the outer contour of the large end is processed to the designed size by eccentric milling. In the process, a 1mm-2mm margin is reserved for the boss end face close to the large end of the forging blank, and a 1mm-2mm margin is reserved for the longitudinal fitting surface close to the large end of the forging blank;

[0050] Heat treatment of forging blanks;

[0051] like Figure 8 As shown, the large end of the forging blank is supported to perform rough machining on the flow channel and inner groove of the forging blank, wherein a 1mm-2mm margin is reserved for the flow channel and a 1mm-2mm margin is reserved for the inner groove;

[0052] like Fig. 9 As shown, align the longitudinal fitting surface and cut the forging blank into left and right half casings;

[0053] like Fig.10 As shown, the large end of the forging blank is supported on the milling machine, and the reverse side of the large end installation edge is pressed, and the diagonal surface runout of the forging blank is found to be less than 0.03mm, and then the small end is auxiliary supported and pressed, and finally the longitudinal fitting surface is milled, and a 0.05mm-0.1mm margin is reserved;

[0054] On the grinding machine, support the large end of the forging blank and press the reverse side of the large end installation edge, find that the diagonal surface runout of the forging blank is less than 0.03mm, then provide auxiliary support for the small end and press the large end, and finally grind the longitudinal fitting surface and ensure that the flatness of the longitudinal fitting surface is less than 0.02mm;

[0055] Machine the bolt holes on the longitudinal mating surface to combine the left and right halves of the receiver;

[0056] Combined milling of angles and inner circles for subsequent alignment;

[0057] Rough machining of the flow channel and the stationary blade slot is performed several times and the spraying area is machined to the final state;

[0058] The left and right halves of the receiver are disassembled for painting and stabilization;

[0059] Then the two halves of the casing are assembled and rough-machined and then sprayed with coating;

[0060] Disassemble the casing into the left and right halves, and grind the large end face against the fitting surface;

[0061] Assemble the left and right halves of the receiver, machine the precision bolt holes on the longitudinal mating surface into place, and then replace the precision hole bolts;

[0062] Finish turning the two end faces, inner flow channel and stationary blade groove to the final size;

[0063] Then finish all bosses, guide vane holes and end holes;

[0064] Finally, the stationary blade retaining groove of the fitting surface is split and processed to complete the processing of the forging on the semi-axial flow casing.

[0065] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for processing a semi-axial flow casing by forging, characterized in that: The following steps are involved: S1, forging to obtain a cylindrical forging blank; S2, rough machining of forging blank; S3, use eccentric milling to process the outer contours of the large end and the small end to the designed size in sequence, wherein a 1mm-2mm margin is reserved for the boss end face of the forging blank, and a 1mm-2mm margin is reserved for the longitudinal fitting surface of the forging blank; S4, heat treating the forging blank; S5, rough machining the flow channel and inner groove of the forging blank, wherein a 1mm-2mm margin is reserved for the flow channel and a 1mm-2mm margin is reserved for the inner groove; S6, wire cutting the forging blank into left and right half casings; S7, the longitudinal fitting surface is machined to the design size, and then the boss end face, flow channel and inner groove are machined to the design size to obtain the forged half axial flow casing.

2. The method for processing a semi-axial flow casing by forging according to claim 1, characterized in that: Step S3 specifically includes the following steps: S31, support the large end of the forging blank and press the installation edge of the large end, then use eccentric milling to process the outer contour of the small end to the designed size, and during the processing, reserve a 1mm-2mm margin on the boss end face close to the small end of the forging blank, and reserve a 1mm-2mm margin on the longitudinal fitting surface close to the small end of the forging blank; S32, support the small end of the forging blank and press the small end mounting edge, then use eccentric milling to process the outer contour of the large end to the designed size. During the processing, leave a 1mm-2mm margin on the boss end face close to the large end of the forging blank, and leave a 1mm-2mm margin on the longitudinal fitting surface close to the large end of the forging blank.

3. The method for machining a semi-axial flow casing using a forging according to claim 2, characterized in that: The steps between step S31 and step S32 include: Mark the outer contour of the small end of the forging blank.

4. The method for machining a semi-axial flow casing using a forging according to claim 1, characterized in that: Step S2 specifically includes the following steps: S21, clamping the forging blank to pre-roughen the small end of the forging blank, and then removing the inner hole, end face and outer circle of the forging blank close to the small end with the maximum profile of the forging blank rotation, and leaving at least 3mm margin; S22, support the small end of the forging blank and press the small end mounting edge to pre-roughen the large end of the forging blank, and then use the maximum contour of the forging blank to rotate to remove the inner hole, end face and outer circle near the large end of the forging blank, and reserve at least 3mm margin.

5. The method for machining a semi-axial flow casing using a forging according to claim 1, characterized in that: In step S3, the specific steps of eccentric milling are as follows: First, use a Φ16mm milling cutter for rough machining and leave a 0.5mm-1mm margin, then use a Φ8mm milling cutter for fine machining, and finally use Φ4mm and Φ2mm milling cutters to clean the corners of the part's outer contour or the boss connection.

6. The method for machining a semi-axial flow casing using a forging according to claim 5, characterized in that: In step S3, the processing parameters of various milling cutters are as follows: Φ16 milling cutter: Linear speed is 80m / s-90m / s, feed rate is 200mm / min-230mm / min; Φ8 milling cutter: Linear speed is 40m / s-50m / s, feed rate is 110mm / min-120mm / min; Φ4 milling cutter: Linear speed is 30m / s-40m / s, feed rate is 50mm / min-60mm / min; Φ2 milling cutter: linear speed is 15m / s-20m / s, feed rate is 20mm / min-30mm / min.

7. The method for machining a semi-axial flow casing by forging according to any one of claims 1 to 5, characterized in that: In step S7, the specific steps of first processing the longitudinal bonding surface to the designed size are as follows: S71, support the large end of the forging blank on the milling machine, and press the reverse side of the large end installation edge, find that the diagonal surface runout of the forging blank is less than 0.03mm, then provide auxiliary support for the small end, and press the small end, and finally mill the longitudinal fitting surface, and reserve a margin of 0.05mm-0.1mm; S72, support the large end of the forging blank on the grinder, and press the reverse side of the large end mounting edge, align the diagonal surface runout of the forging blank to be less than 0.03 mm, then provide auxiliary support for the small end, and press the large end, and finally grind the longitudinal fitting surface, and ensure that the flatness of the longitudinal fitting surface is less than 0.02 mm.

8. The method for machining a semi-axial flow casing using a forging according to claim 7, characterized in that: In steps S71 and S72, when the small end and the large end are compressed, a micrometer is used to check the change before and after compression, and ensure that the change before and after is less than 0.005 mm.

9. The method for machining a semi-axial flow casing by forging according to any one of claims 1 to 5, characterized in that: The method further includes the following steps between step S1 and step S2: Mark the forging blank.

10. The method for machining a semi-axial flow casing using a forging according to claim 9, characterized in that: The method further includes the following steps between step S2 and step S3: Re-mark the forging blank.

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