Milling tool and method for machining thin-walled parts

Abstract

The present application relates to the technical fields of light alloy manufacturing, and particularly relates to a milling processing die and processing method for thin-walled parts; the milling processing die is fixedly connected with the first end face and the second end face of the thin-walled part, so that the thin-walled part is fixed to the milling processing die; the milling processing die is provided with a side face protection plate which circumferentially surrounds the side face of the thin-walled part. The processing die solves the problem of vibration of the side face in the radial direction from inside to outside and from outside to inside during milling processing, and can realize accurate processing of the side wall of the magnesium alloy thin-walled part compared with the prior art.

Description

Technical Field

[0001] This invention relates to the field of lightweight alloy manufacturing technology, and in particular to a milling mold and processing method for thin-walled parts. Background Technology

[0002] Large magnesium alloy thin-walled parts are in high demand in the aerospace field. Since they cannot be welded and the dimensions of casting processes cannot meet the precision requirements, the production of lightweight alloy hollow parts is currently mainly carried out by machine tool processing (turning, milling, etc.).

[0003] For high-precision, large magnesium alloy thin-walled parts, a common processing method is to perform precision machining on a machine tool to obtain more accurate internal structure and dimensions from the cast large magnesium alloy blank. Since clamping thin-walled parts from the outer wall can easily cause deformation, the machine tool fixing molds for thin-walled parts often use a method of supporting and fixing them inside the part's cavity. On the one hand, this type of mold fixing occupies the internal cavity space of the part, especially affecting the fine machining of the inner wall, such as milling. On the other hand, thin-walled parts are prone to vibration during radial machining. Existing mold defects dictate that the part can only be fixed at one end axially, leaving an opening at the other end for the lathe spindle to enter and exit. This lack of mold fixing at the opening end leads to particularly severe vibration, seriously affecting the machining accuracy of the equipment. Furthermore, for large magnesium alloy thin-walled parts, the vibration phenomenon on the sidewalls is even more severe due to the reduced radial cross-sectional curvature.

[0004] Currently, there is an urgent market need for machining equipment and methods for large magnesium alloy thin-walled parts to solve the problems of fixation and reduced machining accuracy due to vibration during machining. Furthermore, during the finishing of magnesium alloy materials, slow feed rates make the magnesium alloy prone to oxidation and even combustion, posing a serious safety hazard. Excessive feed rates increase the instability of the contact between the tool and the magnesium alloy, further exacerbating vibration. Therefore, there is an urgent need to improve the existing magnesium alloy machining processes. Summary of the Invention

[0005] Based on the above analysis, the present invention aims to provide a milling mold and processing method for thin-walled parts, in order to solve at least one of the problems in the prior art, such as poor mold fixing stability, easy vibration, and poor safety in magnesium alloy processing.

[0006] The objective of this invention is mainly achieved through the following technical solutions:

[0007] The present invention provides a milling die for a thin-walled part, the thin-walled part comprising: a first end face, a second end face, and a side face connecting the first end face and the second end face; the milling die is fixedly connected to both the first end face and the second end face of the thin-walled part, thereby fixing the thin-walled part to the milling die; the milling die is provided with a circumferentially surrounding and fitting protective plate on the side face of the thin-walled part.

[0008] Preferably, the milling die has a first pressure plate at one end that is pressed and connected to the first end face, and a first bottom fixing member at the other end that is pressed and connected to the second end face; the milling die also has a first pull rod; the outer circumferential edge of the first pressure plate and the outer circumferential edge of the first bottom fixing member are fixedly connected by the first pull rod.

[0009] Preferably, the first pull rod is provided with multiple circumferentially along the side; the guard plate surrounds the side circumferentially and is provided with multiple axially arranged first through holes; the first through holes correspond one-to-one with the first pull rods and pass through the first through holes.

[0010] Preferably, the side of the protective plate is also provided with a plurality of radially arranged second through holes, and the outer side of the thin-walled part is connected to the outside through the second through holes.

[0011] Preferably, the guard plate includes guard plate units spliced ​​along the axial direction of the thin-walled parts; the guard plate has an adjustable connection structure at the connection between the guard plate units.

[0012] Preferably, the height of the guard plate is set lower than the axial height of the thin-walled part blank.

[0013] Preferably, the wall thickness of the guard plate is greater than the wall thickness of the thin-walled part blank, and an axial gap is provided between the guard plate and the first pressure plate.

[0014] Preferably, the first pull rod is detachably fixedly connected to the first pressure plate and the first bottom fixing member.

[0015] Preferably, the first tie rod is symmetrically arranged relative to the axis center of the thin-walled part.

[0016] A method for machining thin-walled parts, using the milling mold described above.

[0017] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0018] (1) By setting a first pressure plate, a first bottom fixing member, a first tie rod and a guard plate in the milling mold, the present invention can achieve pressing and fixing of thin-walled parts, while greatly reducing the adverse effects of vibration on machining accuracy during side machining; it improves the defects of easy vibration and poor machining accuracy when machining the side of thin-walled parts from the inside to the outside in the prior art.

[0019] (2) The present invention fixes the guard plate radially by the first tie rod and presses it circumferentially around the side, which improves the rigidity of the side of the thin-walled part blank. When the milling cutter processes the first groove, the guard plate provides circumferential support force to the side. This support force is opposite to the force applied by the milling cutter, thus making the thin-walled part blank stable and less prone to vibration or deformation from the outside to the inside. On the one hand, the side of the guard plate and the arched structure of the guard plate can effectively disperse the force applied by the milling cutter. On the other hand, the circumferential support force provided by the guard plate to the side means that the guard plate applies force evenly at each point of contact with the side, thus preventing deformation of the side of the thin-walled part blank caused by local stress concentration. Therefore, when the thin-walled part blank is milled, the guard plate can provide support force in both radial directions, thereby reducing vibration and deformation in both radial directions.

[0020] (3) By setting the bottom of the guard plate to be fixedly connected to the first bottom fixing member, and the side of the guard plate to be attached to the side of the thin-walled part blank, the noise of the processing area during milling can be transmitted to the machine tool through the first bottom fixing member, reducing the noise from spreading into the air and reducing environmental noise.

[0021] (4) By setting through holes in the protective plate, the present invention facilitates the monitoring of the wall thickness of each area during milling; at the same time, the through holes improve ventilation and heat dissipation during side processing, which helps to prevent the blank processing surface from overheating, causing deformation or even damage and burning of the blank.

[0022] (5) This invention uses specially made vertical lathe machining molds and milling molds to process thin-walled parts with annular grooves on the end face. It adopts a "roughing-semi-finishing-finishing" processing method, which reduces the deformation and mechanical damage caused by the accumulated stress of thin-walled materials and improves the processing accuracy. Each processing includes one milling operation and one turning operation. This invention uses vertical lathe machining molds to gradually thin the outer circle of the side wall of the thin-walled part, and the rigidity of the side wall gradually weakens. In the subsequent milling operation, the rigidity of the side of the thin-walled part blank is improved by setting a guard plate in the milling mold. The guard plate can provide support force in both radial directions when the thin-walled part blank is milled, thereby reducing vibration and deformation in both radial directions. At the same time, in order to cope with the decrease in the rigidity of the side wall of the thin-walled part and avoid the deformation of the side wall during vertical lathe machining, this invention sets an internal support structure and an external support structure in the turning mold to fix the second end face, ensuring the dimensional accuracy of structures such as the side milling window.

[0023] (6) By providing a positioning block on the inner side of the cast thin-walled part blank, and using the line connecting the center of the positioning block in the radial plane as the reference in the first vertical lathe process, the present invention can greatly reduce the workload of machine tool alignment and zeroing in subsequent processes while meeting the accuracy requirements; and further utilizes the positioning block and the rotation axis to correct the position and determine the machining reference positioning line; and further utilizes the reference hole on the end face of the machining reference positioning line as the transmission medium of the original reference, ensuring the continuity of the reference and improving the machining accuracy.

[0024] (7) The present invention uses laser scanning imaging technology to preliminarily determine the wall thickness of each section of the casting, determine the correction position of the rotation axis centerline, and adjust and coordinate the wall thickness of each processing part based on the correction axis centerline to make the wall thickness of the part as uniform as possible before processing, so as to ensure that the processing allowance of each surface is uniform and the wall thickness is uniform to meet the requirements. While ensuring the accuracy of the reference scribing, it greatly reduces the workload of machine tool alignment and zeroing in subsequent processes.

[0025] (8) According to the different processing parts, the present invention adopts the method of processing in different areas, dividing the arc surface, and then planning the processing trajectory in each segmented area to process window by window, instead of fixing the thin-walled part blank, controlling the movement of the tool, reducing the displacement of the tool movement, avoiding the processing vibration caused by the excessive overhang of the tool, thereby ensuring the processing accuracy and improving the processing efficiency.

[0026] (9) The present invention provides an internal support structure and an external support structure in the machining mold. The second pressure plate provides a force for the thin-walled part to be pressed and tightened between the second pressure plate and the second bottom fixing member. The internal support structure and the second bottom fixing member provide a support force from the inside of the thin-walled part to the outside for the second end face. These two forces in opposite directions make the second pressure plate balanced, realize the fixation of the second end face, reduce the deformation and chatter of the second end face during machining by the machining tool, and improve the machining accuracy.

[0027] (10) The present invention can achieve stable pressing and fixing of the corners of thin-walled parts by setting a connecting pressure plate, an external support rod and a second tie rod on the external support structure of the machining mold, instead of using a long connecting pressure plate passing through the center area of ​​the second end face as in the prior art. Therefore, it also improves the defect of the thin-walled part fixing mold interfering with the machining of the lathe tool in the prior art.

[0028] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained through the embodiments described and the accompanying drawings, which are particularly pointed out. Attached Figure Description

[0029] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0030] Figure 1 This is a 45° top view of a large magnesium alloy thin-walled part with a groove on its thin-walled end face, according to one embodiment of the present invention.

[0031] Figure 2 This is a 45° bottom view of a large magnesium alloy thin-walled part with a groove on the thin-walled end face according to one embodiment of the present invention.

[0032] Figure 3 This is a 45° top view of a milling die for thin-walled parts according to one embodiment of the present invention;

[0033] Figure 4 This is a view of the installation method of a milling mold for thin-walled parts according to one embodiment of the present invention;

[0034] Figure 5 This is a cross-sectional view of plane AA of a view of the installation method of a milling mold for thin-walled parts in one embodiment of the present invention;

[0035] Figure 6 This is a view of the installation method of the machining mold for thin-walled parts according to one embodiment of the present invention;

[0036] Figure 7 This is a BB-section view of the installation method of the machining mold for thin-walled parts in one embodiment of the present invention;

[0037] Figure 8 This is a schematic diagram of a machining method for thin-walled parts according to one embodiment of the present invention;

[0038] Figure 9 This is a schematic diagram of a milling process for thin-walled parts according to one embodiment of the present invention;

[0039] Figure 10 This is a flowchart illustrating a processing method for a large magnesium alloy thin-walled part with an annular groove on its end face, according to one embodiment of the present invention.

[0040] Figure label:

[0041] Thin-walled part blank 1; side 101; first end face 102; second end face 103; window 1011; positioning block 1012; first groove 1013; annular groove 1031; milling mold 2; first pressure plate 201; guard plate 202; first bottom fixing part 203; first pull rod 204; second through hole 2021; first through hole 2022; external support structure 301; second bottom fixing part 303; internal support structure 305; second pressure plate 307; connecting pressure plate 3011; external support rod 3012; second pull rod 3013; inner support plate 3051; inner support rod 3052; on rotary worktable 4; three-jaw chuck 5; machine tool work platform 6; machining tool 7. Detailed Implementation

[0042] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which constitute a part of the present invention and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0043] It should be noted that in this invention, the axial direction is perpendicular to the two end faces of the thin-walled part, and the radial direction is parallel to the two end faces of the thin-walled part.

[0044] This invention discloses a large, thin-walled part with a groove on its end face, such as... Figure 1 and Figure 2 As shown, it includes: a first end face 102, a second end face 103 and a side surface 101 connecting the first end face 102 and the second end face 103; the first end face 102 is an unobstructed free end face, and the second end face 103 is a hollow annular end face; the inner side of the hollow annular surface of the second end face 103 is provided with an annular groove 1031.

[0045] like Figure 1 As shown, the side 101 is provided with multiple windows 1011, and at least one set of windows 1011 is symmetrically arranged relative to the axis center of the thin-walled part; after the thin-walled part blank is fixed by the milling mold, the milling cutter penetrates the thin-walled part blank through the first end face 102 to process the windows 1011 in the side 101 to obtain windows 1011 that meet the target size.

[0046] It should be noted that the blank of the thin-walled part is obtained by casting. The dimensional accuracy of the window 1011 and other dimensions in the blank obtained by casting cannot meet the requirements. Therefore, it is necessary to further process it with milling tools to obtain the specified shape and accuracy.

[0047] It should be noted that, Figure 2 The annular groove 1031 is obtained by machining the second end face 103 after the thin-walled part blank is fixed by a machining mold.

[0048] The side 101 of the thin-walled part is provided with a plurality of positioning blocks 1012, and at least one set of positioning blocks 1012 is symmetrically arranged relative to the axial center of the thin-walled part.

[0049] It should be noted that the side 101 of the thin-walled part blank 1 has multiple windows 1011, and the windows 1011 need to be machined one by one by rotating the part blank using milling. Therefore, it is necessary to determine the rotation angle of the part blank and the rotating platform connected to it in order to match the machining of the next window 1011 after the machining of adjacent windows 1011 is completed.

[0050] Specifically, a baseline for the thin-walled part is constructed using two symmetrically positioned locating blocks: the center line connecting the centers of a set of symmetrically positioned locating blocks 1012 is used as the machining baseline, with the initial position being when the machining baseline is placed vertically; by determining the angle between the line connecting the center of window 1011 and the part's axis and the machining baseline, the angle α required for the part blank and its connected rotating platform to rotate to the machining baseline position is determined; based on the α of adjacent windows 1011, the rotation angle of the part blank and its connected rotating platform relative to the initial position is determined when machining adjacent windows 1011.

[0051] like Figure 1 As shown, a plurality of spaced first grooves 1013 are provided on the side surface 101 near the first end face 102.

[0052] In practice, the first groove 1013 is obtained by a milling cutter machining from the outside to the inside on the side 101.

[0053] The thin-walled part has thin-walled characteristics. Specifically, the ratio of the wall thickness of the first end face 102, the second end face 103, and the side face 101 to the outer diameter of the thin-walled part is 1:200 to 1000.

[0054] It should be noted that vibration and deformation are mainly affected by the relative values ​​of wall thickness and part diameter. The smaller the relative ratio of wall thickness to part diameter, the more obvious the thin-walled characteristics of the part are, and the machining accuracy will be significantly reduced due to machining vibration and deformation.

[0055] Specifically, thin-walled parts can be made of any one of carbon steel, stainless steel, titanium alloy, aluminum alloy, or magnesium alloy.

[0056] On one hand, the present invention discloses a milling mold for thin-walled parts, which is used for side processing of thin-walled parts. The milling mold is simultaneously fixedly connected to the first end face 102 and the second end face 103 of the thin-walled parts, so that the thin-walled parts are fixed to the milling mold.

[0057] Specifically, such as Figure 3 , Figure 4 and Figure 5As shown: One end of the milling die 2 is provided with a first pressure plate 201 that is pressed and connected to the first end face 102, and the other end is provided with a first bottom fixing member 203 that is pressed and connected to the second end face 103.

[0058] Specifically, the first pressure plate 201 is a hollow ring structure, and the milling cutter enters the thin-walled part from the first end face 102 to mill inside the thin-walled part or to mill the outside of the thin-walled part.

[0059] Meanwhile, the milling die is also provided with a first tie rod 204; the outer circumferential edge of the first pressure plate 201 and the outer circumferential edge of the first bottom fixing member 203 are fixedly connected by the first tie rod 204, and the first bottom fixing member 203 is fixedly connected to the machine tool platform; the first tie rod 204 provides a clamping force along the direction of the first tie rod 204 to realize the pressing and fixing of thin-walled parts on the machine tool platform.

[0060] Multiple first tie rods 204 are arranged circumferentially along the side 101. A milling die has a guard plate 202 on the side 101 of the thin-walled part to limit radial vibration of the part. The guard plate 202 circumferentially surrounds the side 101 and has multiple axially arranged first through holes 2022. Each first tie rod 204 corresponds to one of the first through holes 2022. The first tie rods 204 pass through the first through holes 2022. The first tie rods 204 arranged circumferentially along the side 101 radially fix the guard plate 202. Simultaneously, after the guard plate 202 circumferentially surrounds and adheres to the side 101, a sufficiently large static friction force is generated, achieving axial fixation of the guard plate 202, thus securing the guard plate 202. When the milling cutter processes the inner wall of the side 101, the guard plate 202 can limit the radial outward deformation or vibration of the thin-walled part.

[0061] It should be noted that the milling machine tool processes the side 101 of the thin-walled part step by step from the inside to the outside of the thin-walled part. Therefore, the radial outward force applied to the side 101 can easily cause deformation or chattering of the side 101. When the wall thickness of the blank is thinned, the adverse effects of deformation or chattering on the machining accuracy will be further increased.

[0062] Compared with the prior art, the present invention, by setting a first pressure plate 201, a first bottom fixing member 203, a first tie rod 204, and a guard plate 202 in the milling mold, can not only press and fix thin-walled parts, but also greatly reduce the adverse effects of vibration on machining accuracy during side machining; thus improving the defects of easy vibration and poor machining accuracy in the side machining of thin-walled parts in the prior art.

[0063] Specifically, such as Figure 4 , Figure 5As shown, the first end face 102 of the thin-walled part is pressed and connected to the first pressure plate 201; the second end face 103 is pressed and connected to the first bottom fixing member 203; the two ends of the first pull rod 204 are respectively fixedly connected to the circumferential edges of the first pressure plate 201 and the first bottom fixing member 203; the first pull rod 204 is arranged along the circumferential edges of the first pressure plate 201 and the first bottom fixing member 203, and passes through the first through hole 2022, so that the guard plate 202 is radially fixed and is circumferentially pressed and connected to the side 101; the pressed guard plate 202 and the side 101 generate sufficient static friction force to achieve axial fixation of the guard plate 202 and the side 101.

[0064] Specifically, the side of the guard plate 202 is also provided with a plurality of radially arranged second through holes 2021. The outer side of the thin-walled part is connected to the outside through the second through holes. The second through holes are used for ventilation and heat dissipation of the side of the blank when the external equipment detects the wall thickness of the side 101 and processes it.

[0065] Compared with the prior art, the present invention enables the sidewall thickness to be measured during milling by setting a second through hole, and realizes ventilation and heat dissipation through the through hole, thus solving the problems of difficult thickness control and poor heat dissipation in the sidewall machining of thin-walled parts in the prior art.

[0066] It should be noted that heat dissipation is always a critical issue in the machining of thin-walled parts, especially magnesium alloy parts. Excessive heat accumulation can cause magnesium alloys to soften, deform, or even burn. Magnesium alloys are among the few metals that can react simultaneously with nitrogen and oxygen in the air, making temperature control particularly important during machining.

[0067] The guard plate consists of guard plate units spliced ​​along the axial direction of the thin-walled part.

[0068] Preferably, there are two guard plate units, which are spliced ​​together along the axial direction of the thin-walled part to form guard plate 202; the guard plate 202 has an adjustable connection structure 205 at the connection of the two guard plate units, so that the guard plate 202 can match the blanks of thin-walled parts with different outer diameters, and adjust the degree of pressing between the guard plate 202 and the side 101; when the pressing force is large enough, the guard plate 202 and the side 101 generate a sufficiently large static friction force to achieve axial fixation of the guard plate 202.

[0069] In order to process the first groove 1013 on the side 101, the height of the guard plate 202 is set lower than the axial height of the thin-walled part blank, and an axial gap is provided between the guard plate 202 and the first pressure plate 201.

[0070] Specifically, the milling cutter processes the first groove 1013 from the outside to the inside through the gap between the guard plate 202 and the first pressure plate 201.

[0071] Preferably, the wall thickness of the guard plate 202 is greater than the wall thickness of the thin-walled part blank.

[0072] It should be noted that the guard plate 202 is radially fixed by the first tie rod 204 and is circumferentially pressed against the side 101. At the same time, the wall thickness of the guard plate 202 is much greater than that of the thin-walled part blank, which improves the rigidity of the side of the thin-walled part blank. When the milling cutter processes the first groove 1013, the guard plate 202 provides circumferential support force to the side 101. This support force is opposite to the direction of the force applied by the milling cutter, thus making the thin-walled part blank stable and less prone to vibration or deformation from the outside to the inside.

[0073] On the one hand, the side of the guard plate 202 and the arched structure of the guard plate 202 can effectively disperse the force applied by the milling tool; on the other hand, the guard plate 202 provides circumferential support to the side 101, so that the guard plate 202 applies force evenly at each point of contact with the side 101, thus preventing deformation of the side of the thin-walled part blank caused by local stress concentration.

[0074] Compared with existing technologies, the protective plate 202, which surrounds and fits the side of the thin-walled part blank, can provide support in both radial directions during the milling of the side of the thin-walled part blank, thereby reducing vibration and deformation in both radial directions.

[0075] Specifically, the first pull rod is detachably and fixedly connected to the first pressure plate and the first bottom fixing component.

[0076] Preferably, the connection area between the first pull rod and the first pressure plate and the first bottom fixing member is provided with threads, and the first pull rod is fixedly connected to the first pressure plate and the first bottom fixing member by means of a nut that matches the threads.

[0077] Preferably, the first tie rod is symmetrically arranged relative to the axial center of the thin-walled part, so as to provide uniform pressure to the thin-walled part in the radial direction.

[0078] On one hand, this invention discloses a processing mold for a thin-walled magnesium alloy part with an annular groove on its end face, such as... Figure 3 and Figure 6 As shown, this includes the milling mold and turning mold used for machining the inner side wall of thin-walled parts.

[0079] Specifically, regarding the machining mold, the machining mold is used for machining the end face with an annular groove, and is fixedly connected to the first end face and the second end face of the thin-walled part, so that the thin-walled part is fixed to the machining mold.

[0080] Specifically, such as Figure 6 , Figure 7As shown, the machining mold also includes: a second pressure plate 307 and a second bottom fixing member 303; one end of the external support structure 301 is fixedly connected to the second bottom fixing member 303, and the other end is pressed and connected to the outer side of the second pressure plate 307; the inner side of the second pressure plate 307 is pressed and connected to the outer side of the second end face 103, and the external support structure 301 provides the thin-walled part with a force for tightening and pressing between the second pressure plate 307 and the second bottom fixing member 303 through the second pressure plate 307.

[0081] Meanwhile, one side of the internal support structure 305 is pressed and connected to the inner side of the second end face 103, and the other side is fixedly connected to the second bottom fixing member 303. The internal support structure 305 and the second bottom fixing member 303 provide the second end face 103 with a support force from the inside of the thin-walled part to the outside.

[0082] Specifically, the pressing areas of the second end face 103 and the second pressure plate 307 partially overlap, and the annular central edge of the second end face 103 has an area that is not covered by the second pressure plate 307 and is used to process the annular groove 1031.

[0083] Optionally, the internal support structure 305 completely overlaps with the area in the second pressure plate 307 used for processing the annular groove 1031, and the internal support structure 305 provides support for the processing area of ​​the annular groove 1031 from the inside of the second pressure plate 307.

[0084] It should be noted that the machining tool performs the machining of the annular groove 1031 from shallow to deep on the outer side of the second end face 103. At this time, the machining tool applies a pressing force to the second end face 103 from the outside to the inside. Under the action of this force, the second end face 103 will also deform or vibrate, which will affect the machining accuracy. When the wall thickness of the thin-walled part is smaller, the impact of deformation or vibration on accuracy is greater, and the machining difficulty of the part increases accordingly.

[0085] Compared with the prior art, the present invention provides an internal support structure and an external support structure. The second pressure plate provides a force to tighten and press the thin-walled part between the second pressure plate and the second bottom fixing member. The internal support structure and the second bottom fixing member provide a support force from the inside of the thin-walled part to the outside for the second end face. These two forces in opposite directions make the second pressure plate balanced, realize the fixation of the second end face, reduce the deformation and chatter of the second end face during machining, and improve the machining accuracy.

[0086] Specifically, in order to press-fit and fix thin-walled parts during machining, such as Figure 7As shown, the external support structure 301 is provided with a connecting pressure plate 3011, a second tie rod 3013 and an external support rod 3012; the connecting pressure plate 3011 is provided with a through hole; the second tie rod 3013 corresponds to the through hole one by one, one end of the second tie rod 3013 passes through the through hole and is fixedly connected to the connecting pressure plate 3011, and the other end is fixedly connected to the second bottom fixing member 303; a set of side surfaces through which the through hole passes are arranged parallel to the second pressure plate 307, and one side surface of this set of side surfaces presses against the outer edge of the second pressure plate 307.

[0087] When implementing, such as Figure 6 As shown, the second pressure plate 307 is an annular flat plate, and the connecting pressure plate 3011 is a cuboid connecting block, which is pressed against the outer edge of the annular flat plate.

[0088] Optionally, the end of the second pull rod 3013 is provided with a threaded structure, and the second pull rod 3013 passes through the connecting pressure plate 3011 and is fixedly connected to the connecting pressure plate 3011 by a nut.

[0089] It should be noted that the connecting pressure plate 3011 is pressed against the outer edge of the annular plate of the second pressure plate 307 and fixed to the second bottom fixing member 303 by the second tie rod 3013. Therefore, the connection point between the second tie rod 3013 and the second pressure plate 307 does not coincide with the stress point of the connecting pressure plate and the second pressure plate 307. The connecting pressure plate is subjected to reverse stress while pressing the second pressure plate 307, which makes the pressing and fixing method of the connecting pressure plate 3011 and the second pressure plate 307 easy to loosen.

[0090] Furthermore, in order to solve the problem of easy loosening and falling off when the connecting pressure plate 3011 and the second pressure plate 307 are pressed and fixed, the external support structure 301 is provided with an external support rod 3012; one end of the external support rod 3012 is fixedly connected to the connecting pressure plate 3011, and the other end is fixedly connected to the second bottom fixing member 303, and is set away from the thin-walled part relative to the second pull rod 3013.

[0091] Compared with the prior art, the present invention can achieve stable pressing and fixing of the corners of thin-walled parts by setting a connecting pressure plate 3011, an external support rod 3012, and a second tie rod 3013 in the external support structure 301, without having to use a long connecting pressure plate passing through the center area of ​​the second end face as in the prior art. Therefore, it improves the defect of interference of the thin-walled part fixing mold to the lathe tool processing in the prior art.

[0092] Specifically, to provide inner support for the second end face 103, the internal support structure 305 is provided with an inner support plate 3051 and an inner support rod 3052. The inner support plate 3051 is annular and is coaxially matched with the second end face 103, providing a support force to the second end face 103 from the inside that is opposite to the pressing force of the connecting pressure plate 3011. One end of the inner support rod 3052 is fixedly connected to the inner support plate 3051, and the other end is fixedly connected to the second bottom fixing member 303, providing the inner support plate 3051 with a support force from the inside out that is opposite to the pressing force of the connecting pressure plate 3011.

[0093] Optionally, the inner support plate 3051 and the processing area of ​​the annular groove 1031 are completely overlapped, providing a support force opposite to the pressing force of the connecting pressure plate 3011 for the processing of the annular groove 1031; this can greatly improve the deformation and vibration generated by the processing of grooves in thin-walled parts.

[0094] On the other hand, the present invention provides a method for processing a thin-walled part with an annular groove on its end face, using the aforementioned processing mold for the magnesium alloy thin-walled part with an annular groove on its end face, such as... Figure 10 As shown, it includes the following steps:

[0095] Step 1: Connect the center of the positioning blocks that are symmetrical about the axis as the reference positioning line of the hollow annular end face. Obtain the fitting image of the thin-walled part blank based on laser scanning fitting imaging. Correct the reference positioning line based on the fitting image of the thin-walled part blank. The thin-walled part blank has a side surface, an unobstructed free end face and a hollow annular end face. The inner surface of the side surface is provided with at least two positioning blocks that are symmetrical about the axis.

[0096] Specifically, laser scanning fitting imaging analysis software is used to synthesize a fitted image of the thin-walled part blank from the information of the cast part blank obtained by laser scanning; based on the fitted image of the part blank and the theoretical image of the thin-walled part blank, the deviation between the fitted image and the theoretical image of the thin-walled part blank at each radial section is obtained; and the deviation of each radial section is judged.

[0097] If the deviation of each radial section is less than or equal to the first threshold δ1, no adjustment is made and the reference positioning line is corrected.

[0098] If the deviation of each radial section is greater than the first threshold δ1, adjust the position of the axis of the theoretical image of the thin-walled part blank until the deviation of each radial section is less than or equal to the first threshold δ1, and record the position change value Δ(x, y, z) of the axis of the axis in the spatial coordinate system; in the same spatial coordinate system, obtain the coordinates of the axis of the corrected part blank by changing the axis of the axis of the part blank according to Δ(x, y, z); connect the center of the positioning block and the axis of the corrected part blank in the radial plane, and use the line connecting the two as the corrected reference positioning line.

[0099] In practice, the thin-walled part blank is a hollow thin-walled part blank with two end faces obtained by casting. During processing, the end faces are fixed to the rotating platform and can rotate freely around the axis; the two end faces are set parallel to the radial plane.

[0100] During implementation, the positioning blocks are cast together with the thin-walled part blank in the mold. They can be regular in shape and easy to find the center, such as a cuboid. Multiple sets of positioning blocks can be set, with each pair symmetrical to the central axis.

[0101] It should be noted that the positioning block's setting accuracy on the thin-walled part blank meets the initial alignment requirements, allowing the machining personnel to roughly judge the baseline position and easily adjust the rotation angle of the thin-walled part blank, so that the starting machining position of the thin-walled part blank is close to the machining area.

[0102] It should be noted that the thin-walled part blanks obtained by casting have uneven side wall thickness, which is not an ideal state of uniform wall thickness. If the original design axis is used for machining, products with uneven wall thickness will inevitably be obtained. Therefore, it is necessary to correct the position of the axis so that the thin-walled part blank can be rotated and machined with this position as the axis to obtain products with uniform wall thickness.

[0103] In practice, the spatial coordinate system often uses the axial direction of the thin-walled part as one coordinate axis and the radial direction as the plane containing the other two coordinate axes. The laser scanning fitting imaging analysis software can simultaneously display the fitted image of the part blank and the theoretical image of the thin-walled part blank, calculate the non-overlapping areas of the two, and assign different color labels. Through the color labels, the deviation of each radial plane of the thin-walled part can be intuitively obtained. By adjusting the position of the axis centerline of the fitted image of the part blank, the color labels of each radial plane deviation change, and then the position with the smallest relative radial plane deviation can be selected. This position is used as the corrected position of the axis centerline of the part blank, and the position change value Δ(x, y, z) is calculated. In the spatial coordinate system where the part blank is fixed during processing, the axis centerline is changed according to Δ(x, y, z) to obtain the corrected position of the axis centerline of the part blank. Any positioning block in a set of positioning blocks that are symmetrical about the axis centerline is selected, and the center of the positioning block and the corrected axis centerline of the part blank are connected in the radial plane. The line connecting the two is used as the corrected reference positioning line, thus completing the correction of the reference positioning line.

[0104] Step 2: Perform vertical machining on the two end faces and the outer circle of the side face of the thin-walled part blank after the reference positioning line has been corrected; the vertical machining leaves a margin.

[0105] Specifically, a three-jaw chuck is used to fix the thin-walled part blank from inside, and the free end face of the thin-walled part blank is fixed to the rotary table. The hollow annular end face is set near the end of the machining tool. The machining tool performs machining on the two end faces and the outer circle of the side of the thin-walled part blank from the hollow annular end face to the free end face.

[0106] When implementing, such as Figure 8 As shown, the workpiece blank is fixed on the rotary table 4 using a three-jaw chuck 5, so that it can rotate radially around the machine tool work platform 6. The machining tool 7 completes the outer circle machining of the side 101, the second end face 103 and the first end face 102 of the thin-walled part. At this time, the machine tool work platform 6 is a vertical lathe work platform and the machining tool 7 is a vertical lathe machining tool.

[0107] It should be noted that the three-jaw chuck is a commonly used internal clamping fixture on lathes. It has three jaws, and the distance between the three jaws can be adjusted to clamp and fix hollow parts of different inner diameters from inside the part.

[0108] It should be noted that the allowance for vertical machining mentioned in this article refers to the fact that the vertical machining has not been completed to the size of the formed component, and there is still room for further vertical machining.

[0109] It should be noted that the axis of rotation for machining thin-walled part blanks after completing the datum positioning line correction is the corrected position. Rotating the machining along this axis results in a more uniform wall thickness on the side of the thin-walled part blank. After vertical machining, the cross-sectional shape of the part blank changes compared to the original thin-walled part blank, the wall thickness is uniform, and the center of the part blank cross-section is located on the corrected axis.

[0110] Step 3: Based on the corrected reference positioning line, the side of the thin-walled part blank that has been machined by the vertical lathe is milled. The milling die is equipped with a guard plate that is circumferentially fixed to the side of the thin-walled part blank. The milling process leaves a margin, and two reference holes are set in the non-machined area of ​​the outer edge of the free end face of the thin-walled part blank relative to the axis. The center point of the reference hole is collinear with the corrected reference positioning line.

[0111] Specifically, the milling mold used for machining the inner side of thin-walled parts is fixed to the outside of the thin-walled part blank, with the hollow annular end face of the thin-walled part blank fixed to the rotary table, and the free end face set near the end of the milling tool; the milling tool performs milling on the side of the thin-walled part blank from the inner side to the outer side.

[0112] When implementing, such as Figure 9As shown, a milling die is used to fix the part blank on the rotary table 4, so that it can rotate radially around the machine tool working platform 6. One end of the milling die is provided with a first pressure plate 201 that is pressed and connected to the first end face 102, and the other end is provided with a first bottom fixing member 203 that is pressed and connected to the second end face 103. The machining tool 7 penetrates into the interior of the thin-walled part to complete the side 101 from the inside out, and removes the excess material from the window 1011. At this time, the machine tool working platform 6 is a milling machine working platform, and the machining tool 7 is a milling tool.

[0113] It should be noted that the side of the part blank has multiple windows, and the part blank needs to be rotated to process each window one by one. Therefore, it is necessary to determine the rotation angle of the part blank and the rotating platform connected to it when processing adjacent windows.

[0114] Specifically, obtain the line connecting the center of the side window and the axis of the part blank, and further obtain the angle between the line connecting the window center and the axis and the corrected reference positioning line; use this angle to calculate the rotation angle of the part blank and its connected rotary platform when machining adjacent windows.

[0115] During implementation, the initial position is taken as when the machining datum line is placed vertically; by determining the angle between the line connecting the center of the window and the axis of the workpiece blank and the machining datum line, the angle α that the workpiece blank and its connected rotating platform need to rotate to the position of the machining datum line is determined; based on the α of the adjacent windows, the rotation angle of the workpiece blank and its connected rotating platform relative to the initial position is determined when machining the adjacent windows.

[0116] Specifically, on the corrected reference positioning line, two reference holes (not shown in the figure) are distributed relatively from the axis line in the unmachined area of ​​the outer edge of the hollow annular end face of the thin-walled part blank.

[0117] It should be noted that the milling allowance mentioned in this article refers to the fact that the milling process has not reached the size of the formed component, and there is still room for further milling.

[0118] It should be noted that the positioning block is removed after milling, and the corrected datum positioning line needs to be continued to be transferred. Therefore, a datum hole is set as the transfer medium for the datum positioning line.

[0119] Preferably, the reference hole is the target machining hole for the thin-walled part.

[0120] Step 4: Stabilize the blank of the thin-walled part after milling.

[0121] Specifically, the thin-walled part blanks that have been milled are subjected to a heating-air cooling-reheating-furnace cooling process to remove residual stress from the turning and milling processes.

[0122] Step 5: Perform a second vertical turning process on the two end faces and the outer circle of the side face of the thin-walled part blank after the stabilization treatment is completed. The second vertical turning process leaves a margin.

[0123] Specifically, a three-jaw chuck is used to fix the thin-walled part blank from inside, and the free end face of the thin-walled part blank is fixed to the rotary table, with the hollow annular end face set near the end of the machining tool; the machining tool performs machining on the two end faces and the outer circle of the side of the thin-walled part blank from the hollow annular end face to the free end face.

[0124] like Figure 8 As shown, the workpiece blank is fixed on the rotary table 4 using a three-jaw chuck 5, so that it can rotate radially around the machine tool work platform 6. The machining tool 7 completes the outer circle machining of the side 101, the second end face 103 and the first end face 102 of the thin-walled part. At this time, the machine tool work platform 6 is a vertical lathe work platform and the machining tool 7 is a vertical lathe machining tool.

[0125] Step 6: Based on the reference hole, perform a second milling process on the thin-walled part blank that has completed the second vertical lathe machining. The milling die for the second milling process is equipped with a protective plate that is circumferentially fitted and fixed to the side of the thin-walled part blank. The second milling process leaves a margin.

[0126] Specifically, the milling mold used for machining the inner side of thin-walled parts is fixed to the outside of the thin-walled part blank, with the hollow annular end face of the thin-walled part blank fixed to the rotary table, and the free end face set near the end of the milling tool; the milling tool performs milling on the side of the thin-walled part blank from the inner side to the outer side.

[0127] When implementing, such as Figure 9 As shown, a milling die is used to fix the part blank on the rotary table 4, so that it can rotate radially around the machine tool working platform 6. One end of the milling die is provided with a first pressure plate 201 that is pressed and connected to the first end face 102, and the other end is provided with a first bottom fixing member 203 that is pressed and connected to the second end face 103. The machining tool 7 penetrates into the interior of the thin-walled part to complete the side 101 from the inside out, and removes the excess material from the window 1011. At this time, the machine tool working platform 6 is a milling machine working platform, and the machining tool 7 is a milling tool.

[0128] Specifically, the straight line connecting the center points of the reference holes is used as the reference positioning line for the second milling machining.

[0129] During implementation, the line connecting the center points of the reference holes is marked with a scribing device and used as the reference positioning line for the second milling machine machining; the line connecting the center of the side window and the axis of the part blank is obtained, and the angle between the line connecting the center of the window and the axis and the reference positioning line for the second milling machine machining is further obtained; the initial position is taken when the reference positioning line is placed vertically; by determining the angle between the line connecting the center of the window and the axis of the part and the machining reference line, the angle α that the part blank and its connected rotary platform need to rotate to the position of the machining reference line is determined; based on α of the adjacent windows, the rotation angle of the part blank and its connected rotary platform relative to the initial position is determined when machining the adjacent windows.

[0130] Step 7: Based on the reference point and the turning die for machining the thin-walled end face with the annular groove, perform a third vertical turning operation on the thin-walled part blank that has completed the second milling operation, and machine the outer circle of the thin-walled part blank to the target size and obtain the annular groove of the central annular end face.

[0131] Specifically, a machining mold for machining thin-walled end faces with annular grooves is used to fix the thin-walled part blank from the inside and outside. The free end face of the thin-walled part blank is fixed to the rotary table, and the hollow annular end face is set near the end of the machining tool. The machining tool performs machining on the two end faces and the outer circle of the side of the thin-walled part blank from the hollow annular end face to the free end face.

[0132] When implementing, such as Figure 6 , Figure 7 As shown, the machining mold includes: a second pressure plate 307, an external support structure 301, an internal support structure 305, and a second bottom fixing member 303; one end of the external support structure 301 is fixedly connected to the second bottom fixing member 303, and the other end is pressed and connected to the outer side of the second pressure plate 307; the inner side of the second pressure plate 307 is pressed and connected to the outer side of the second end face 103, and the external support structure 301 and the second pressure plate 307 provide a force for tightening and pressing the second end face 103 and the thin-walled part between the second pressure plate 307 and the second bottom fixing member 303; one side of the internal support structure 305 is pressed and connected to the inner side of the second end face 103, and the other side is fixedly connected to the second bottom fixing member 303, and the internal support structure 305 and the second bottom fixing member 303 provide a supporting force from the inside to the outside of the thin-walled part for the second end face 103.

[0133] During implementation, the machining tool processes the inner edge of the hollow annular end face from shallow to deep to obtain the annular groove on the central annular end face.

[0134] Step 8: Based on the reference hole, perform a third milling operation on the thin-walled part blank that has completed the third vertical lathe machining. The milling die for the third milling operation is equipped with a protective plate that is circumferentially fitted and fixed to the outer side of the thin-walled part blank. The milling operation leaves a margin. The third milling operation processes the window on the side of the thin-walled part blank to the target size.

[0135] Specifically, the milling mold used for machining the inner side of thin-walled parts is fixed to the outside of the thin-walled part blank, with the hollow annular end face of the thin-walled part blank fixed to the rotary table, and the free end face set near the end of the milling tool; the milling tool performs milling on the side of the thin-walled part blank from the inner side to the outer side.

[0136] When implementing, such as Figure 9 As shown, a milling die is used to fix the part blank on the rotary table 4, so that it can rotate radially around the machine tool working platform 6. One end of the milling die is provided with a first pressure plate 201 that is pressed and connected to the first end face 102, and the other end is provided with a first bottom fixing member 203 that is pressed and connected to the second end face 103. The machining tool 7 penetrates into the interior of the thin-walled part to complete the side 101 from the inside out, and removes the excess material from the window 1011. At this time, the machine tool working platform 6 is a milling machine working platform, and the machining tool 7 is a milling tool.

[0137] Specifically, the straight line connecting the center points of the reference holes is used as the reference positioning line for the third milling operation.

[0138] During implementation, the line connecting the center points of the reference holes is marked with a scribing device and used as the reference positioning line for the third milling machine machining; the line connecting the center of the side window and the axis of the part blank is obtained, and the angle between the line connecting the center of the window and the axis and the reference positioning line for the third milling machine machining is further obtained; the initial position is taken when the reference positioning line is placed vertically; by determining the angle between the line connecting the center of the window and the axis of the part and the machining reference line, the angle α that the part blank and its connected rotary platform need to rotate to the position of the machining reference line is determined; based on α of the adjacent windows, the rotation angle of the part blank and its connected rotary platform relative to the initial position is determined when machining the adjacent windows.

[0139] Specifically, such as Figure 3 , Figure 4 and Figure 5As shown: the milling die is fixedly connected to the first end face 102 and the second end face 103 of the thin-walled part; one end of the milling die is provided with a first pressure plate 201 that is pressed and connected to the first end face 102, and the other end is provided with a first bottom fixing member 203 that is pressed and connected to the second end face 103; at the same time, the outer circumferential edge of the first pressure plate 201 and the outer circumferential edge of the first bottom fixing member 203 are fixedly connected by a first tie rod 204 at corresponding positions, and the first bottom fixing member 203 is fixedly connected to the machine tool platform; the first tie rod 204 provides a clamping force along the direction of the first tie rod 204 to realize the pressing and fixing of the thin-walled part on the machine tool platform.

[0140] The milling die has a guard plate 202 on the side 101 of the thin-walled part to limit the radial vibration of the thin-walled part; the guard plate 202 surrounds the side 101 circumferentially and has a first through hole 2022; a first pull rod 204 passes through the first through hole 2022, and the first pull rod 204, which is arranged circumferentially along the side 101, enables the guard plate 202 to surround and fit the side 101 circumferentially, and limits the radial outward deformation or vibration of the thin-walled part when the milling cutter processes the inner wall of the side 101.

[0141] It should be noted that the milling cutter processes the side 101 of the thin-walled part from the inside out, applying a radially outward force to the side 101, which can easily cause deformation or chattering of the side 101. When the wall thickness of the blank becomes thinner, the adverse effects of deformation or chattering on machining accuracy will further increase.

[0142] Compared with existing technologies, this invention employs specially designed vertical lathe machining dies and milling dies to process thin-walled parts with annular grooves on the end faces. It uses a "roughing-semi-finishing-finishing" processing method, reducing deformation and mechanical damage caused by accumulated stress in the thin-walled material and improving processing accuracy. Each processing step includes one milling operation and one turning operation. The vertical lathe machining dies gradually thin the outer diameter of the sidewall of the thin-walled part, gradually reducing its rigidity. In subsequent milling operations, a protective plate is installed in the milling die to improve the rigidity of the side surface of the thin-walled part blank. The protective plate provides support in both radial directions during milling, thereby reducing vibration and deformation in both radial directions. Simultaneously, to address the decreased sidewall rigidity and prevent deformation during vertical lathe machining, this invention incorporates internal and external support structures in the turning die to fix the second end face, ensuring the dimensional accuracy of structures such as side milling windows.

[0143] On the other hand, by setting a first pressure plate, a first bottom fixing member, a first tie rod, and a guard plate in the milling mold, the present invention can not only press and fix thin-walled parts, but also greatly reduce the adverse effects of vibration on machining accuracy during side milling; it improves the defects of easy vibration and poor machining accuracy when milling the side of thin-walled parts from the inside to the outside in the prior art.

[0144] In addition, this invention uses laser scanning imaging technology to preliminarily determine the wall thickness of each section of the casting, determine the correction position of the rotation axis centerline, and adjust and coordinate the wall thickness of each processing part based on the correction axis centerline to the machining datum line, so as to make the wall thickness of the part as uniform as possible before processing, so as to ensure that the machining allowance of each surface is uniform and the wall thickness meets the requirements. While ensuring the accuracy of the datum scribing, it greatly reduces the workload of machine tool alignment and zeroing in subsequent processes.

[0145] In addition, by providing a positioning block on the inner side of the cast thin-walled part blank, and using the line connecting the center of the positioning block in the radial plane as the datum in the first vertical lathe process, the present invention can greatly reduce the workload of machine tool alignment and zeroing in subsequent processes while meeting the accuracy requirements; and further utilizes the positioning block and the rotation axis centerline to correct the position and determine the machining datum positioning line; and further sets a datum hole on the machining datum positioning line as the transmission medium of the original datum, ensuring the continuity of the datum and improving the machining accuracy.

[0146] In addition, after the blank is corrected by positioning reference line and axis, the present invention removes the deformation and precision error of the casting process by vertical lathe machining, so that the rotation axis of the blank coincides with the geometric center of its end face, and provides a reference for the next step of machining in combination with the positioning reference line.

[0147] Specifically, the method for obtaining the fitted image of the thin-walled part blank based on laser scanning fitting imaging in step 1 is as follows: using sensors densely distributed on the inner and outer surfaces of the thin-walled part blank as data sampling points, using laser scanning to obtain the coordinates of the sensors in the spatial coordinate system, and fitting a three-dimensional image of the thin-walled part blank based on the sensor spatial coordinate information.

[0148] Specifically, step 1, which involves correcting the reference positioning lines based on the fitted image of the thin-walled part blank, includes:

[0149] S101: Using laser scanning fitting imaging software, the centerline of the fitted image of the part blank and the theoretical image of the thin-walled part blank are coincident. The thickness of each region of the radial section of the part blank is compared, the deviation is automatically obtained, and the deviation is marked with color according to the size of the deviation.

[0150] S102: If the deviation of each radial section is less than or equal to the first threshold δ1, no adjustment is made and the reference positioning line is corrected.

[0151] If the deviation of each radial section is greater than the first threshold δ1, adjust the position of the axis of the theoretical image of the thin-walled part blank until the deviation of each radial section is less than or equal to the first threshold δ1, and record the position change value Δ(x, y, z) of the axis in the spatial coordinate system.

[0152] S103: Construct the same spatial coordinate system as the fitted image of the part blank and the theoretical image of the thin-walled part blank. In this coordinate system, obtain the coordinates of the corrected axis of the part blank by changing the axis of the part blank according to △(x, y, z).

[0153] S104: In the radial plane where the center of the positioning block of the part blank is located, connect the center of any positioning block and the axis of the corrected part blank, and use the line connecting the two as the corrected reference positioning line to complete the reference positioning line correction.

[0154] Preferably, the first threshold δ1 is 0.02 mm.

[0155] It should be noted that the determination of the first threshold δ1 is related to the accuracy of the dial indicator itself. The first threshold δ1 < 0.02 mm, which is outside the accuracy range of the dial indicator.

[0156] Specifically, the vertical lathe machining described in step 2 includes the following steps:

[0157] S201: Take the fixed thin-walled part blank, select 1 / 4 to 1 / 2 of the machining amount of the vertical lathe, and perform trial machining to obtain a trial machining blank sample;

[0158] S202: Inspect the eccentricity of the machined blank sample rotating about the axis of the calibrated part blank;

[0159] S203: Determine the degree of eccentricity;

[0160] If the eccentricity is less than the second threshold δ2, then machining is performed;

[0161] If the eccentricity is greater than the second threshold δ2, repeat S101-S104 to correct the axis of the part blank again until the eccentricity is less than the second threshold δ2.

[0162] Specifically, the eccentricity described in S202 is checked by a dial indicator, including the following steps: fixing the fixed end of the dial indicator to the machine tool platform, and contacting the test end with the side of the part blank until a reading is obtained; recording the change of the dial indicator reading during the part blank's rotation of one revolution.

[0163] Specifically, the eccentricity is evaluated by the change η in the dial indicator reading, and η satisfies: η = S max -S min , among which, S max S represents the maximum value of the dial indicator pointer reading. min This represents the minimum reading of the dial indicator.

[0164] Optionally, the second threshold δ2 is set to 0.02 mm.

[0165] It should be noted that the determination of the second threshold δ2 is related to the accuracy of the dial indicator itself. The second threshold δ2 < 0.02 mm, which is outside the accuracy range of the dial indicator.

[0166] To meet the requirements of magnesium alloy machining, the feed rate of the workpiece blank during the first machining operation is 0.4 mm / r to 0.6 mm / r. If it is lower than 0.4 mm / r, local overheating is likely to occur, leading to deformation or even spontaneous combustion of the magnesium alloy; if it is higher than 0.6 mm / r, it is difficult to meet the accuracy requirements.

[0167] To improve local heat dissipation, a cooling airflow of 0.6MPa to 0.8MPa is provided during the machining of the part blank.

[0168] It should be noted that water or oil-based cutting coolants will react with high-temperature magnesium alloys. Compared with the prior art, this invention uses a 0.6MPa to 0.8MPa airflow for cooling, which solves the problem of local heat dissipation and is conducive to further reducing the feed rate and improving machining accuracy and machining safety.

[0169] To reduce deformation during machining, the cutting depth of the workpiece blank should be 0.5 to 2. If the cutting depth of the workpiece blank is greater than 2, deformation is likely to occur when it is fixed by a common three-jaw chuck.

[0170] Specifically, the machining amount of the vertical lathe in step 2 is 2-4 mm.

[0171] Preferably, the machining allowance for the vertical lathe machining in step 2 is 3mm.

[0172] Specifically, step 3 involves milling, obtaining the angle between the line connecting the center of the side window of the part blank and the axis and the corrected reference positioning line, and using this angle to calculate the rotation angle of the part blank and its connected rotary platform when machining adjacent windows. This specifically includes:

[0173] S301: Connect the center of the window to the axis of the workpiece blank in its radial plane. Obtain the angle α between this line and the machining datum line using an angle measuring device. Based on the adjacent order of the windows, number them sequentially as the first window, ..., the nth window, and the corresponding angle α is numbered α1, ..., α2. n ;

[0174] S302: Calculate the difference Δα between any two adjacent windows and the machining baseline, which serves as the rotation angle of the part blank and its connected rotary platform during machining of adjacent windows; where Δα satisfies: Δα=α k -α k-1 , k≤n; k represents the window number, α k Let be the angle between the center of the k-th window and the line connecting the center of the part blank to the machining datum line in its radial plane.

[0175] Specifically, during the processing of adjacent windows, the rotation angle of the part blank and the rotating platform connected to it is adjusted by means of the angle scale on the rotating platform itself.

[0176] Specifically, step 3 involves obtaining the reference hole using a machine tool drilling equipment, and inserting a locating pin to correct the position of the reference hole, including:

[0177] S311: A first coordinate axis is set in the vertical horizontal plane, the rotation axis of the machine tool rotary platform is used as the second coordinate axis, and a third coordinate axis is set in the horizontal plane in a direction perpendicular to the first and second coordinate axes to construct a spatial coordinate system;

[0178] S312: Select one of the locating pins of the reference hole as the first locating pin, set a dial indicator on the machine tool spindle to contact the highest point of the side of the first locating pin, and record the dial indicator reading.

[0179] S313: Select the locating pin of another reference hole as the second locating pin, rotate the machine tool rotary platform 180° using its own scale, keep the coordinates of the machine tool spindle on the first and second coordinate axes unchanged, and make contact at the highest point on the side of the second locating pin. Record the dial indicator reading.

[0180] S314: Calibrate the reference hole based on two dial indicator readings;

[0181] If the difference between two dial gauge readings is less than the third threshold δ3, then the reference hole setting is deemed to meet the requirements.

[0182] If the difference between two dial indicator readings is greater than the third threshold δ3, then the original reference hole is enlarged based on the corrected reference positioning line, and matching positioning pins are used to repeat S312-S313 until the difference between two dial indicator readings is less than the third threshold δ3.

[0183] Specifically, the accuracy of the reference hole setting is evaluated by the change in the dial indicator reading η, and η satisfies: η = S max -S min , among which, S max S represents the maximum dial indicator reading from two separate dial indicator readings. min This represents the minimum dial indicator reading between two dial indicator readings.

[0184] Optionally, the third threshold δ3 is set to 0.02 mm.

[0185] It should be noted that the determination of the third threshold δ3 is related to the accuracy of the dial indicator itself. The third threshold δ3 < 0.02 mm, which is outside the accuracy range of the dial indicator.

[0186] Specifically, enlarging the original reference hole based on the corrected reference positioning line includes: repositioning the center of the enlarged reference hole on the corrected reference positioning line and then enlarging the hole; the enlarged diameter of the reference hole should be larger than the original reference hole, and the enlarged reference hole should completely cover the area of ​​the original reference hole, thereby eliminating the error caused by the deviation in the position setting of the original reference hole.

[0187] It should be noted that the distance between the center of the reference hole and the calibrated reference positioning line can be adjusted according to actual needs. Therefore, when taking the dial indicator reading in steps S312-S313, it is not necessary to take the coordinate reading of the third coordinate axis in the direction of the calibrated reference positioning line.

[0188] Specifically, the milling amount in step 3 is 1mm to 5mm.

[0189] Preferably, the milling amount in step 3 is 2mm to 3mm.

[0190] Specifically, the determination of the highest point on the side of the pin in S312 and S313 includes:

[0191] S321: A first coordinate axis is set in the vertical horizontal plane, the rotation axis of the machine tool rotary platform is used as the second coordinate axis, and a third coordinate axis is set in the horizontal plane in a direction perpendicular to the first and second coordinate axes. A spatial coordinate system is constructed with the center of the machine tool rotary platform as the origin.

[0192] S322: Select one of the reference holes and insert a matching locating pin. Set a dial indicator on the machine tool spindle to contact the top area of ​​one side of the locating pin and show a reading. Keep the coordinates of the first and second axes of the machine tool spindle unchanged. Move the machine tool spindle parallel to the third axis while keeping the dial indicator reading non-zero. Record the spatial coordinates when the dial indicator reading is at its minimum as the coordinates of the highest point on one side of the locating pin.

[0193] S323: Using the same method, obtain the coordinates of the highest point on the other end of the positioning pin. Compare the coordinates of the highest points at both ends, and take the larger value of the first coordinate axis as the coordinate of the highest point on the side of the pin.

[0194] It should be noted that the pins are generally selected from smooth and flat cylinders. Due to the limited accuracy of drilling the reference hole, the flatness of the hole is poor, and the positioning pin may not be horizontal after installation, so it cannot be used to further correct the reference hole.

[0195] Furthermore, in order to correct the longitudinal flatness of the reference hole opening, S311 and S312 also include a flatness correction for the reference hole opening:

[0196] S324: Compare the coordinates (x1, y1, z1) and (x2, y2, z2) of the highest points at both ends obtained in steps S322 and S323, and obtain the coordinate differences △x, △y, △z for each coordinate axis; where △x = |x1-x2|, △y = |y1-y2|, △z = |z1-z2|;

[0197] If Δx, Δy, and Δz are all less than the fourth threshold δ4, then the flatness of the opening of the reference hole is deemed to meet the requirements.

[0198] If any of the values ​​of △x, △y, and △z is greater than the fourth threshold δ4, then the hole is enlarged based on the corrected reference positioning line in the original reference hole, and the matching positioning pin is used to repeat S322-S323 until △x, △y, and △z are all less than the fourth threshold δ4.

[0199] Optionally, the fourth threshold δ4 is related to the machining accuracy of the machine tool.

[0200] Compared with existing technologies, this method uses segmented processing based on different processing areas. The arc surface is divided into sections, and then processing trajectories are planned in each section for processing window by window, instead of fixing the thin-walled part blank. This controls the movement of the tool, reduces tool displacement, and avoids processing vibration caused by excessive tool overhang, thereby ensuring processing accuracy and improving processing efficiency.

[0201] Specifically, the stabilization process described in step 4 further reduces residual stress from the pre-processing process, including the following steps:

[0202] S401: Heat treatment at 120±10℃ for 2h~6h, then air-cooled down to room temperature;

[0203] S402: Heat-treat at 120±10℃ for 2h~6h, then cool to room temperature with the furnace.

[0204] The thermal stress generated during the positive temperature-air cooling-positive temperature-furnace cooling process is superimposed on the original residual stress, exceeding the yield strength of the material and causing plastic deformation, thereby reducing the original residual stress and further improving the plasticity and machinability of the cylindrical part material.

[0205] Specifically, step S401 uses air cooling to quickly superimpose the thermal stress on the outer surface with the original residual stress, resulting in plastic deformation; step S402 uses furnace cooling to slowly lower the temperature, which can reduce the thermal stress on the outer and inner surfaces of the part blank caused by air cooling; overall, it achieves the effect of reducing the stress caused by rough machining.

[0206] It should be noted that the first vertical turning and milling are roughing processes. Due to the large amount of material removed, the accumulated stress during the machining process is relatively large, so stabilization treatment is required to remove the accumulated stress. The second vertical turning, second milling, and third vertical turning and third milling processes have smaller material removal and the workpiece is thinner, so it is not easy to accumulate stress.

[0207] Specifically, in the second machining step described in step 5, in order to meet the requirements of magnesium alloy machining, the feed rate of the part blank is 0.4mm / r to 0.6mm / r; if it is lower than 0.4mm / r, local overheating is likely to occur, leading to deformation or even spontaneous combustion of the magnesium alloy; if it is higher than 0.6mm / r, it is difficult to meet the accuracy requirements.

[0208] To improve local heat dissipation, a cooling airflow of 0.6MPa to 0.8MPa is provided during the machining of the part blank.

[0209] It should be noted that water or oil-based cutting coolants will react with high-temperature magnesium alloys. Compared with the prior art, this invention uses a 0.6MPa to 0.8MPa airflow for cooling, which solves the problem of local heat dissipation and is conducive to further reducing the feed rate and improving machining accuracy and machining safety.

[0210] To reduce deformation during machining, the cutting depth of the workpiece blank should be 0.5 to 2. If the cutting depth of the workpiece blank is greater than 2, deformation is likely to occur when it is fixed by a common three-jaw chuck.

[0211] Specifically, the second vertical machining in step 5 leaves a margin and does not machine the outer circle to the final size. The machining amount in the second vertical machining is 1 to 3 mm.

[0212] Preferably, the machining amount of the second vertical lathe machining in step 5 is 2mm.

[0213] Specifically, step 6 involves performing a second milling operation. This involves obtaining the angle between the line connecting the center of the side window of the workpiece blank and the axis, and the corrected reference positioning line. Using this angle, the rotation angle of the workpiece blank and its connected rotary platform during the machining of adjacent windows is calculated. This specifically includes:

[0214] S601: Connect the center of the window to the axis of the workpiece blank in its radial plane. Obtain the angle α between this line and the machining datum line using an angle measuring device. Based on the adjacent order of the windows, number them sequentially as the first window, ..., the nth window, and the corresponding angle α is numbered α1, ..., α2. n ;

[0215] S602: Calculate the difference Δα between any two adjacent windows and the machining baseline, which serves as the rotation angle of the part blank and its connected rotary platform during machining of adjacent windows; where Δα satisfies: Δα=αk -α k-1 , k≤n; k represents the window number, α k Let be the angle between the center of the k-th window and the line connecting the center of the part blank to the machining datum line in its radial plane.

[0216] Specifically, during the processing of adjacent windows, the rotation angle of the part blank and the rotating platform connected to it is adjusted by means of the angle scale on the rotating platform itself.

[0217] During implementation, record the angle scale of the rotating platform when the previous window was being processed, and rotate the angle scale of the rotating platform by Δα so that the window to be processed is in the processing position of the previous window.

[0218] Step 7 describes the third vertical lathe machining process, which involves machining the outer diameter of the thin-walled part blank to the target size and obtaining the annular groove on the central annular end face. This includes:

[0219] S701: Using the above-mentioned machining mold for machining thin-walled end faces with annular grooves, the free end face of the thin-walled part blank is fixed on the rotary table, and the hollow annular end face is positioned near the end of the machining tool.

[0220] S702: Using machining tools to machine the outer diameter of the side of a thin-walled part blank to the target size;

[0221] S703: Use a turning tool to machine the inner edge of the central annular end face of a thin-walled part blank to obtain an annular groove.

[0222] Specifically, S701, which describes fixing the free end face of the thin-walled part blank to the rotary table, includes:

[0223] S7011: One end of the external support structure is fixedly connected to the second bottom fixing member, and the other end is pressed and connected to the outer side of the second pressure plate; the inner side of the second pressure plate is pressed and connected to the outer side of the second end face.

[0224] S7012: One side of the internal support structure is pressed and connected to the inner side of the second end face, and the other side is fixedly connected to the second bottom fastener.

[0225] Compared with the prior art, the present invention sets up an internal support structure and an external support structure in the machining mold, and provides a force for the thin-walled part to be tightened and pressed between the second pressure plate and the second bottom fixing member through the second pressure plate. The internal support structure and the second bottom fixing member provide a support force from the inside of the thin-walled part to the outside for the second end face. These two forces in opposite directions make the second pressure plate balanced, realize the fixation of the second end face, reduce the deformation and chatter of the second end face during machining by the machining tool, and improve the machining accuracy.

[0226] To meet the requirements for magnesium alloy machining, the feed rate of the workpiece blank during the third machining operation was 0.2 mm / r.

[0227] 0.4mm / r; below 0.2mm / r, local overheating is likely to occur, leading to deformation or even spontaneous combustion of the magnesium alloy; above 0.4mm / r, it is difficult to meet the accuracy requirements.

[0228] To improve local heat dissipation, a cooling airflow of 0.7MPa to 0.8MPa is provided during the machining of the part blank.

[0229] It should be noted that water or oil-based cutting coolants will react with high-temperature magnesium alloys. Compared with the prior art, the present invention uses a wind-cooled airflow of 0.8MPa to 1.0MPa for cooling, which increases the air pressure, helps to solve the problem of local heat dissipation, and can reduce the feed rate, improve machining accuracy and machining safety.

[0230] To reduce deformation during machining, the cutting depth of the part blank is 0.2 to 0.5. Since the thickness of the part is reduced during the third machining, the cutting depth of the part blank is less than or equal to 0.5. At the same time, a machining mold for machining thin-walled end faces with annular grooves is used to fix the part and avoid deformation.

[0231] Step 8, the third milling process, machining the window on the side of the thin-walled part blank to the target size, includes:

[0232] S801: Using the milling die for machining the inner side wall of a thin-walled part, the hollow annular end face of the thin-walled part blank is fixed on the rotary table, with the free end face positioned close to the end of the machining tool.

[0233] S802: Connect the center of the window to the axis of the workpiece blank in its radial plane. Obtain the angle α between this line and the machining datum line using an angle measuring device. Based on the adjacent order of the windows, number them sequentially as the first window, ..., the nth window, and the corresponding angle α is numbered α1, ..., α2. n ;

[0234] S803: Calculate the difference Δα between any two adjacent windows and the machining datum line, which serves as the rotation angle of the part blank and its connected rotary platform during machining of adjacent windows; where Δα satisfies: Δα=α k -α k-1 , k≤n; k represents the window number, α k Let be the angle between the center of the k-th window and the line connecting the center of the part blank to the machining datum line in its radial plane.

[0235] S804: With the vertical state of the machining datum line as the initial position, set the machining area of ​​the milling tool to be in the horizontal plane below the axis, rotate the rotary platform by α1 degrees so that the line connecting the first window and the axis is in the initial position, the machining plane of the first window is in the machining area of ​​the milling tool, and mill the first window to the target size;

[0236] S805: Rotate the rotary platform by α2-α1 degrees so that the machining plane of the second window is in the machining area of ​​the milling tool, and mill the second window to the target size;

[0237] S806: Rotate the rotating platform by α3-α2, ..., α n -α n-1 The degree is adjusted so that the machining plane of the third window, ..., the nth window is in the machining area of ​​the milling cutter, and the third window, ..., the nth window is milled to the target size; the third milling machining of the thin-walled part blank is completed.

[0238] Specifically, S801, which describes fixing the free end face of the thin-walled part blank to the rotary table, includes:

[0239] S8011: The first pressure plate of the milling die is pressed and connected to the first end face, and the first bottom fixing part is pressed and connected to the second end face;

[0240] S8012: The outer circumferential edge of the first pressure plate is fixedly connected to the corresponding position of the outer circumferential edge of the first bottom fixing member by the first tie rod, and the first bottom fixing member is fixedly connected to the machine tool platform.

[0241] S8013: The first tie rod is passed through the first through hole provided around the side, and the first tie rod provided around the side achieves the circumferential wrapping of the guard plate to fit the side.

[0242] Compared with the prior art, the present invention, by setting a first pressure plate, a first bottom fixing member, a first tie rod, and a guard plate in the milling mold, can not only press and fix thin-walled parts, but also greatly reduce the adverse effects of vibration on machining accuracy during side machining; thus improving the defects of easy vibration and poor machining accuracy in the side machining of thin-walled parts in the prior art.

[0243] The third milling process also includes a step of using measuring equipment to check the wall thickness at various points on the side.

[0244] Meanwhile, the radially arranged second through hole on the guard plate allows the side wall thickness to be measured during milling, and ventilation and heat dissipation are achieved through the through hole, solving the problems of difficult thickness control and poor heat dissipation in the existing technology for side wall machining of thin-walled parts.

[0245] Specifically, such as Figure 3 , Figure 4As shown, the side of the protective plate 202 is provided with multiple second through holes 2021. Through the second through holes 2021, external equipment can be connected to detect the wall thickness at various points on the side 101.

[0246] During implementation, ultrasonic, laser, or X-ray equipment is used to detect the wall thickness at each point on the side 101.

[0247] The processing method for the thin-walled magnesium alloy parts further includes a step of inspecting the cracks and damage of the thin-walled parts after step 8. Specifically, the inspection is carried out using the radiographic testing method of GJ / B 1187A-2001, and the acceptance standard is the requirements for Class I castings in QJ20708 Rare Earth Heat-Resistant Cast Magnesium Alloys and Casting Specifications. The selected method is X-ray fluorescence flaw detection.

[0248] The processing method for the thin-walled magnesium alloy parts includes a micro-arc oxidation treatment step on the surface of the thin-walled magnesium alloy parts after the step of inspecting the cracks and damage of the thin-walled parts. Specifically, a high-voltage electric arc is used to generate a magnesium oxide layer with good heat resistance and hardness on the surface of the magnesium alloy, thereby improving the oxidation resistance, surface hardness and wear resistance of the magnesium alloy.

[0249] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method of processing a magnesium alloy thin-walled part, characterized by, The thin-walled part is processed by using a processing die, and the processing die of the thin-walled part comprises a milling processing die; The side surface of the part blank has a plurality of windows; The thin-walled part comprises a first end surface, a second end surface and a side surface connecting the first end surface and the second end surface; the first end surface is a free end surface without shielding, and the second end surface is a hollow annular end surface; an annular groove is arranged on the inner side of the hollow annular second end surface; The milling processing die is fixedly connected with the first end surface and the second end surface of the thin-walled part at the same time, so that the thin-walled part is fixed to the milling processing die; a guard plate is arranged on the side surface of the thin-walled part and circumferentially surrounds and adheres to the side surface; The milling processing die is used for milling the inner wall of the side surface of the thin-walled part, and a guard plate is arranged on the side surface of the thin-walled part and circumferentially surrounds and adheres to the side surface; The side surface of the guard plate is further provided with a plurality of second through holes arranged in the radial direction; the outer side surface of the thin-walled part is communicated with the outside through the second through holes; The inner side surface of the thin-walled part blank is provided with positioning blocks, and the inner surface of the side surface is provided with at least two positioning blocks which are symmetric about the center of the axis; the processing method comprises: The center of the positioning blocks symmetric about the center of the axis is connected as a reference positioning line of the hollow annular end surface, a fitting image of the thin-walled part blank is obtained based on laser scanning fitting imaging, and the reference positioning line is corrected based on the fitting image of the thin-walled part blank; the thin-walled part blank has one side surface, one free end surface without shielding and one hollow annular end surface; the information of the cast part blank obtained by laser scanning is synthesized into a fitting image of the thin-walled part blank by using a laser scanning fitting imaging analysis software; the deviations of the fitting image of the thin-walled part blank and the theoretical image of the thin-walled part blank in each radial cross section are obtained based on the fitting image of the part blank and the theoretical image of the thin-walled part blank; the deviations in each radial cross section are judged: If the deviations in each radial cross section are less than or equal to a first threshold value δ1, no adjustment is made, and the reference positioning line is completed; If the deviations in each radial cross section are greater than the first threshold value δ1, the position of the axis of the theoretical image of the thin-walled part blank is adjusted until the deviations in each radial cross section are less than or equal to the first threshold value δ1, and the position change value Δ(x, y, z) of the axis in the space coordinate system is recorded; the axis of the part blank is changed according to Δ(x, y, z) in the same space coordinate system to obtain the axis coordinate of the corrected part blank; the center of the positioning block and the axis of the corrected part blank are connected in the radial plane, and the connecting line is taken as the corrected reference positioning line.

2. The method of processing a magnesium alloy thin-walled part according to claim 1, characterized by, One end of the milling processing die is provided with a first pressing plate in pressure-fit connection with the first end surface, and the other end is provided with a first bottom fixing member in pressure-fit connection with the second end surface; the milling processing die is further provided with a first pull rod; the circumferential outer edge of the first pressing plate is fixedly connected with the circumferential outer edge of the first bottom fixing member through the first pull rod.

3. The method of processing a magnesium alloy thin-walled part according to claim 2, characterized by, A plurality of first pull rods are arranged circumferentially along the side surface; the guard plate circumferentially surrounds the side surface and is provided with a plurality of first through holes arranged in the axial direction; the first through holes correspond to the first pull rods one by one and pass through the first through holes.

4. The method of processing a magnesium alloy thin-walled part according to claim 3, characterized by, The shield plate comprises shield plate units which are spliced along the axial direction of the thin-walled part; and the shield plate is provided with a connecting structure with adjustable connecting gap at the connecting position between the shield plate units.

5. The method of processing a magnesium alloy thin-walled part according to claim 4, characterized by, The height of the shield plate is lower than the axial height of the thin-walled part blank.

6. The method of processing a magnesium alloy thin-walled part according to claim 5, characterized by, The wall thickness of the shield plate is greater than the wall thickness of the thin-walled part blank, and an axial gap is arranged between the shield plate and the first pressing plate.

7. The method of processing a magnesium alloy thin-walled part according to claim 3, characterized by, The first pull rod is detachably fixedly connected with the first pressing plate and the first bottom fixing member.

8. The method of processing a magnesium alloy thin-walled part according to claim 3, characterized by, The first pull rod is symmetrically arranged relative to the axial center of the thin-walled part.

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