CN116079356B

CN116079356B - Processing die and processing method for thin-walled parts with annular grooves on the end faces

Info

Publication number: CN116079356B
Application number: CN202310229959.1A
Authority: CN
Inventors: 马鹏飞; 安文洁; 宋毅; 张风磊; 石凡; 孟凡杰
Original assignee: Beijing Xinghang Electromechanical Equipment Co Ltd
Current assignee: Beijing Xinghang Electromechanical Equipment Co Ltd
Priority date: 2023-03-10
Filing date: 2023-03-10
Publication date: 2025-03-18
Anticipated expiration: 2043-03-10
Also published as: CN116079356A

Abstract

The present invention relates to the technical field of light alloy manufacturing, and in particular to a processing mold and processing method for a thin-walled part with an annular groove on the end face; the processing mold comprises: a milling processing mold for processing the inner wall of the side of the thin-walled part and a lathe processing mold for processing the thin-walled end face with an annular groove; the milling processing mold is provided with a protective plate surrounding the side surface in a circumferential direction on the side of the thin-walled part; the lathe processing mold is provided with an external support structure for pressing the outside of the central annular end face of the thin-walled part and an internal support structure for supporting the inside of the central annular end face of the thin-walled part, and the external support structure and the internal support structure are used to keep the thin-walled part stable when processing the annular groove. The processing mold solves the deformation and vibration of the second end face during lathe processing and the side vibration during milling processing, and realizes high-precision and stable processing of the side wall and end face of magnesium alloy thin-walled parts.

Description

Processing die and processing method for thin-wall part with annular groove on end face

Technical Field

The invention relates to the technical field of light alloy manufacturing, in particular to a processing die and a processing method for a thin-wall part with an annular groove on the end face.

Background

The large magnesium alloy thin-wall parts have wide requirements in the field of aviation, and the welding processing cannot be performed, and the casting process is difficult to meet the precision requirement in size, so that the production of the light alloy hollow parts mainly adopts machine tool processing (turning, milling and the like).

A common machining mode for high-precision large magnesium alloy thin-wall parts is to machine a cast large magnesium alloy blank to obtain a more accurate internal structure and size, because the thin-wall parts are clamped from the outer side walls to easily cause part deformation, a mode of supporting and fixing the thin-wall parts in a cavity is often adopted for the machine tool machining and fixing the thin-wall parts, on one hand, the mold fixing is extruded to occupy the inner cavity space of the parts, especially the fine machining of the inner walls of the parts is influenced, such as milling machining is particularly influenced, on the other hand, the thin-wall parts are easy to generate tremble during radial machining of the parts, the existing mold defect is determined to be fixed only at one axial end of the parts to be machined, and the other end is provided with an opening end for a lathe spindle to enter and exit, so that the die fixing is lack, the tremble is particularly serious, the machining precision of equipment is seriously influenced, and meanwhile, the tremble phenomenon of the side walls of the parts is more serious due to the reduction of the curvature of radial section of the large magnesium alloy thin-wall parts.

At present, a processing device and a processing method for a large magnesium alloy thin-wall part are urgently needed in the market, and the problems of fixation and reduction of processing precision caused by tremble during processing of the large magnesium alloy thin-wall part are solved. In addition, during the finish machining of the magnesium alloy material, the magnesium alloy is easy to oxidize and even burn due to the low feeding speed, the magnesium alloy machining always has serious potential safety hazard, the feeding speed is too high, and the tremble is further aggravated due to the increase of the contact instability of the cutter and the magnesium alloy, so that the improvement of the magnesium alloy machine tool machining process in the prior art is needed.

Disclosure of Invention

In view of the above analysis, the present invention aims to provide a processing die and a processing method for a thin-walled part with an annular groove on an end surface, which are used for solving at least one of the problems of poor die fixing stability, easy tremble, poor processing safety of magnesium alloy and the like in the prior art.

The aim of the invention is mainly realized by the following technical scheme:

the invention provides a processing die of a thin-wall part with an annular groove on a thin-wall end face, which comprises a milling die and a turning die, wherein the thin-wall part comprises a first end face, a second end face and a side face for connecting the first end face with the second end face;

The milling die is used for milling the inner wall of the side face of the thin-wall part, and a guard plate circumferentially encircling the attached side face is arranged on the side face of the thin-wall part;

The turning mold is used for turning the thin-wall end face of the thin-wall part, which is provided with the annular groove, and is provided with an external supporting structure for pressing the outer part of the hollow annular end face of the thin-wall part and an internal supporting structure for supporting the inner part of the central annular end face of the thin-wall part, and the external supporting structure and the internal supporting structure enable the thin-wall part to be kept stable during the annular groove machining.

Preferably, the turning mold is fixedly connected with the first end face and the second end face of the thin-wall part at the same time, so that the thin-wall part is fixed on the turning mold.

Preferably, the turning mold further comprises a second pressing plate and a second bottom fixing piece, one end of the external supporting structure is fixedly connected with the second bottom fixing piece, the other end of the external supporting structure is connected with the outer side face of the second pressing plate in a pressing mode, and the inner side face of the second pressing plate is connected with the outer side face of the second end face in a pressing mode.

Preferably, the second end surface is partially overlapped with the pressing area of the second pressing plate, and the annular center edge of the second end surface is provided with an area which is not blocked by the second pressing plate and is used for processing the annular groove.

The outer support structure is preferably provided with a connecting pressing plate, a second pull rod and an outer support rod, the connecting pressing plate is provided with through holes, the second pull rods are in one-to-one correspondence with the through holes, one end of each second pull rod penetrates through each through hole and is fixedly connected with the connecting pressing plate, the other end of each second pull rod is fixedly connected with the second bottom fixing piece, a group of side faces penetrating through the through holes are arranged in parallel with the second pressing plate, and one side face of the group of side faces is in pressing abutting joint with the outer edge of the second pressing plate.

Preferably, the external supporting structure is further provided with an external supporting rod, one end of the external supporting rod is fixedly connected with the connecting pressing plate, the other end of the external supporting rod is fixedly connected with the second bottom fixing piece, and the external supporting rod is arranged away from the thin-wall part relative to the second pull rod.

Preferably, one side of the inner supporting structure is connected with the inner side of the second end face in a pressing mode, and the other side of the inner supporting structure is fixedly connected with the second bottom fixing piece.

Preferably, the milling die is fixedly connected with the first end face and the second end face of the thin-wall part at the same time, so that the thin-wall part is fixed on the milling die.

Preferably, one end of the milling die is provided with a first pressing plate in press fit connection with the first end face, the other end of the milling die is provided with a first bottom fixing piece in press fit connection with the second end face, the milling die is further provided with a first pull rod, and the circumferential outer side edge of the first pressing plate is fixedly connected with the circumferential outer side edge of the first bottom fixing piece through the first pull rod.

The processing method of the thin-wall part with the annular groove on the end face of the thin wall uses the processing die.

Compared with the prior art, the invention has at least one of the following beneficial effects:

(1) According to the invention, a special vertical lathe processing die and a milling processing die are adopted to process the thin-wall part with the annular groove on the end face, and a processing mode of rough processing, semi-finishing and finishing is adopted, so that deformation and mechanical damage caused by accumulated stress of a thin-wall material are reduced, and the processing precision is improved; the invention adopts a vertical lathe processing die to gradually thin the outer circle of the side wall of the thin-wall part, the rigidity of the side wall is gradually weakened, a guard plate is arranged on the milling processing die in the subsequent milling processing, the rigidity of the side surface of a blank of the thin-wall part is improved, the guard plate can provide supporting force for two radial directions when the blank of the thin-wall part is milled, thereby reducing vibration and deformation in two radial directions, and simultaneously, the rigidity of the side wall of the thin-wall part is reduced to prevent the side wall from deforming during vertical lathe processing.

(2) According to the invention, the internal supporting structure and the external supporting structure are arranged in the turning mold, the second pressing plate provides the force for tightening and pressing the thin-wall part between the second pressing plate and the second bottom fixing piece, the internal supporting structure and the second bottom fixing piece provide the supporting force from the inside to the outside of the thin-wall part for the second end face, and the forces in the two opposite directions balance the stress of the second pressing piece, so that the second end face is fixed, the deformation and vibration of the second end face during the machining of the turning tool are reduced, and the machining precision is improved.

(3) According to the invention, the connecting pressing plate, the external supporting rod and the second pull rod are arranged on the external supporting structure of the turning mold, so that stable lamination fixation of corners of the thin-wall part can be realized, and the long connecting pressing plate passing through the center area of the second end surface is not needed to be adopted in the prior art, thus the defect that the thin-wall part fixing mold interferes with the machining of the lathe tool in the prior art is also overcome.

(4) According to the invention, the first pressing plate, the first bottom fixing piece, the first pull rod and the guard plate are arranged in the milling die, so that the pressing and fixing of the thin-wall part is realized, meanwhile, the adverse effect of tremble on the machining precision during side machining is greatly reduced, and the defects of easy tremble and poor machining precision in the prior art when the side of the thin-wall part is machined from inside to outside are overcome.

(5) According to the invention, the guard plate is radially fixed through the first pull rod and circumferentially surrounds and presses the side surface, so that the rigidity of the side surface of the thin-wall part blank is improved, the guard plate provides circumferential supporting force for the side surface when the milling cutter is used for machining the first groove, the supporting force is opposite to the force application direction of the milling cutter, so that the thin-wall part blank is stable and is not easy to shake or deform from outside to inside, on one hand, the side surface of the guard plate and the dome-shaped structure of the guard plate can effectively disperse the force application of the milling cutter, on the other hand, the guard plate provides circumferential supporting force for the side surface, and the guard plate uniformly applies force to each point contacted with the side surface, so that the deformation of the side surface of the thin-wall part blank caused by local stress concentration can be prevented, and therefore, the guard plate can provide supporting force for two radial directions when the thin-wall part blank is milled, and shake and deformation in two radial directions can be reduced.

(6) According to the invention, the bottom of the guard plate is fixedly connected with the first bottom fixing piece, and the side surface of the guard plate is in fit connection with the side surface of the thin-wall part blank, so that noise in a machining area during milling can be transmitted to a machine tool through the first bottom fixing piece, the noise is reduced from spreading into the air, and the environmental noise is reduced.

(7) Through the through holes in the guard plate, the wall thickness of each region is conveniently monitored by milling, and meanwhile, ventilation and heat dissipation during side surface machining are improved through the through holes, so that deformation caused by overheating of a machining surface of a blank, and even damage and burning of the blank are prevented.

(8) According to the invention, the positioning block is arranged on the inner side surface of the cast thin-wall part blank, the radial plane connecting line of the center of the positioning block is used as a reference in the first vertical lathe process, so that the workload of machine tool alignment and zero setting in the subsequent working procedure can be greatly reduced on the basis of meeting the precision requirement, the positioning block and the rotating shaft axis are further utilized to correct the position to determine the processing reference positioning line, the reference hole is further arranged on the end surface of the processing reference positioning line to be used as a transmission medium of an original reference, the continuation of the reference is ensured, and the processing precision is improved.

(9) The invention adopts the laser scanning imaging technology to preliminarily judge the wall thickness condition of each section of casting, determines the correction position of the rotating axis, adjusts and coordinates the wall thickness dimension of each processing part based on the corrected axis to the processing datum line, and ensures that the wall thickness of the part is uniform before processing as much as possible, so as to ensure that the processing allowance of each surface is uniform, the wall thickness uniformity meets the requirement, the datum scribing precision is ensured, and the work load of machine tool alignment and zero setting in the subsequent working procedure is greatly reduced.

(10) According to the invention, the arc surface is divided by adopting the subareas according to different processing parts, and then the processing tracks are planned in each division area to process one window by one instead of fixing a thin-wall part blank, so that the movement of the cutter is controlled, the movement displacement of the cutter is reduced, the processing tremble caused by the overlong overhanging of another cutter is avoided, the processing precision is ensured, and the processing efficiency is improved.

In the invention, the technical schemes can be mutually combined to realize more preferable combination schemes. Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention may be realized and attained by the embodiments of the invention particularly pointed out in the written description and drawings.

Drawings

The drawings are only for purposes of illustrating particular embodiments and are not to be construed as limiting the invention, like reference numerals being used to refer to like parts throughout the several views.

FIG. 1 is a 45-degree schematic top view of a large magnesium alloy thin-wall part with a groove on the thin-wall end face in one embodiment of the invention;

FIG. 2 is a 45-degree bottom view schematic diagram of a large magnesium alloy thin-wall part with a groove on the thin-wall end face in one embodiment of the invention;

FIG. 3 is a 45 top view of a thin-walled part milling die in accordance with one embodiment of the present invention;

FIG. 4 is a view showing an installation mode of a milling die for a thin-walled part according to an embodiment of the present invention;

FIG. 5 is a cross-sectional view taken along the plane A-A of a view of an installation of a milling tool for thin-walled parts in accordance with one embodiment of the present invention;

FIG. 6 is a view showing an installation mode of a thin-wall part turning mold in one embodiment of the present invention;

FIG. 7 is a cross-sectional view of the B-B side of an installation mode view of a turning mold for thin-walled parts in accordance with an embodiment of the present invention;

FIG. 8 is a schematic diagram of a turning mode of a thin-walled part according to an embodiment of the present invention;

FIG. 9 is a schematic diagram of a milling mode of a thin-walled part according to an embodiment of the present invention;

FIG. 10 is a flow chart of a method for processing a large magnesium alloy thin-wall part with an annular groove on the end face of the thin-wall part in an embodiment of the invention.

Reference numerals:

Part blank 1, side 101, first end face 102, second end face 103, window 1011, locating block 1012, first recess 1013, annular recess 1031, milling tool 2, first platen 201, guard 202, first bottom mount 203, first tie bar 204, connecting structure 205, second through hole 2021, first through hole 2022, outer support structure 301, second bottom mount 303, inner support structure 305, second platen 307, connecting platen 3011, outer support bar 3012, second tie bar 3013, inner support plate 3051, inner support bar 3052, rotary table 4, three-jaw clamp 5, machine tool table 6, and machining tool 7.

Detailed Description

The following detailed description of preferred embodiments of the invention is made in connection with the accompanying drawings, which form a part hereof, and together with the description of the embodiments of the invention, are used to explain the principles of the invention and are not intended to limit the scope of the invention.

In the invention, the axial direction is perpendicular to the two end face directions of the thin-wall part, and the radial direction is parallel to the two end face directions of the thin-wall part.

The invention discloses a thin-wall part with grooves on end surfaces, which is shown in fig. 1 and 2 and comprises a first end surface 102, a second end surface 103 and a side surface 101 for connecting the first end surface 102 with the second end surface 103, wherein the first end surface 102 is a free end surface without shielding, the second end surface 103 is a hollow annular end surface, and an annular groove 1031 is formed in the hollow annular inner side of the second end surface 103.

As shown in FIG. 1, a side 101 is provided with a plurality of windows 1011, at least one group of windows 1011 are arranged symmetrically relative to the center of the axis of the thin-wall part, after the thin-wall part blank is fixed by a milling die, the milling tool penetrates into the thin-wall part blank through a first end face 102, and the windows 1011 in the processing of the side 101 are processed to obtain the windows 1011 which meet the target size.

The thin-wall part blank is obtained by casting, and the dimensional accuracy of a window 1011 and the like in the blank obtained by casting cannot meet the requirement, so that a milling cutter is required to further process to obtain a specified shape and accuracy.

In fig. 2, the annular groove 1031 is obtained by fixing the thin-walled part blank with a turning mold and then machining the second end surface 103 with a turning tool.

The side 101 of the thin-wall part is provided with a plurality of positioning blocks 1012, and at least one group of positioning blocks 1012 are arranged symmetrically relative to the axis center of the thin-wall part.

The side 101 of the part blank has a plurality of windows 1011, and the windows 1011 need to be machined one by rotating the part blank by milling, so that it is necessary to determine the rotation angle of the part blank and its connected rotating platform after finishing machining the adjacent windows 1011 to match the machining of the next window 1011.

The method comprises the steps of constructing a datum line of a thin-wall part by using two positioning blocks which are arranged symmetrically relative to the axis center of the thin-wall part, taking a central connecting line of a group of positioning blocks 1012 which are arranged symmetrically as a machining datum line and taking the machining datum line as an initial position when the machining datum line is vertically arranged, determining the included angle between the central connecting line of a window 1011 and the part axis center and the machining datum line, further determining the angle alpha of the window 1011 to the machining datum line, at which the part blank and a rotating platform connected with the part blank need to be rotated, and determining the rotating angle of the part blank and the rotating platform connected with the part blank relative to the initial position when the adjacent window 1011 is machined based on the alpha of the adjacent window 1011.

As shown in fig. 1, the side surface 101 is provided with a plurality of first grooves 1013 spaced apart from each other on the side near the first end surface 102.

In practice, the first recess 1013 is obtained by milling the side 101 from the outside to the inside.

The thin-wall part has thin-wall characteristics, and 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-wall part is 1:200-1000.

It should be noted that chatter and deformation are mainly affected by the relative values of the wall thickness and the diameter of the part, and the smaller the relative ratio of the wall thickness to the diameter of the part is, the more remarkable thin-wall characteristic is exhibited by the part, and the machining accuracy is remarkably reduced due to machining chatter and deformation.

Specifically, the thin-wall part can be any one of carbon steel, stainless steel, titanium alloy, aluminum alloy and magnesium alloy.

In one aspect, the invention discloses a processing die of a magnesium alloy thin-wall part with an annular groove on the end face, which comprises a milling die and a turning die as shown in fig. 3 and 6.

Regarding the milling mold, the milling mold is used for processing the side inner wall of the thin-wall part and is fixedly connected with the first end face 102 and the second end face 103 of the thin-wall part, so that the thin-wall part is fixed on the milling mold.

Specifically, as shown in fig. 3, 4 and 5, one end of the milling die 2 is provided with a first pressing plate 201 in press-fit connection with the first end surface 102, and the other end is provided with a first bottom fixing member 203 in press-fit connection with the second end surface 103.

Specifically, the first pressing plate 201 has a hollow annular structure, and the milling cutter enters the thin-wall part from the first end face 102 for internal milling or external milling.

Meanwhile, the milling die is further provided with a first pull rod 204, the circumferential outer side edge of the first pressing plate 201 is fixedly connected with the circumferential outer side edge of the first bottom fixing piece 203 through the first pull rod 204, the first bottom fixing piece 203 is fixedly connected with the machine tool platform, and the first pull rod 204 provides a fastening force along the direction of the first pull rod 204 to achieve the press fit fixing of the thin-wall part on the machine tool platform.

The first pull rods 204 are circumferentially arranged along the side face 101, the milling mold is provided with guard plates 202 for limiting radial vibration of the thin-wall part on the side face 101 of the thin-wall part, the guard plates 202 circumferentially surround the side face 101 and are provided with first through holes 2022 which are axially arranged, the first through holes 2022 correspond to the first pull rods 204 one by one, the first pull rods 204 penetrate through the first through holes 2022, the first pull rods 204 circumferentially arranged along the side face 101 enable the guard plates 202 to be radially fixed, meanwhile, enough static friction force is generated after the guard plates 202 circumferentially surround and fit with the side face 101, axial fixation of the guard plates 202 is achieved, and further fixation of the guard plates 202 is achieved. Guard 202 limits radially outward deformation or chatter of the thin-walled part when the milling cutter is machining the inner wall of side 101.

The milling machine tool gradually processes the side face 101 of the thin-walled part from the inside to the outside of the thin-walled part, so that a radially outward force is applied to the side face 101, deformation or chatter of the side face 101 is liable to occur, and when the wall thickness of a processed blank becomes thin, adverse effects of deformation or chatter on processing accuracy are further increased.

Compared with the prior art, the milling die has the advantages that the first pressing plate 201, the first bottom fixing piece 203, the first pull rod 204 and the guard plate 202 are arranged in the milling die, so that the pressing fixation of the thin-wall part is realized, meanwhile, the adverse effect of tremble on the machining precision during side machining is greatly reduced, and the defects of easiness in tremble and poor machining precision in the side machining of the thin-wall part in the prior art are overcome.

Specifically, as shown in fig. 4 and 5, the first end surface 102 of the thin-walled part is in press fit connection with the first pressing plate 201, the second end surface 103 is in press fit connection with the first bottom fixing member 203, two ends of the first pull rod 204 are fixedly connected with the circumferential edges of the first pressing plate 201 and the first bottom fixing member 203 respectively, the first pull rod 204 is arranged along the circumferential edges of the first pressing plate 201 and the first bottom fixing member 203 and penetrates through the first through hole 2022, so that the guard plate 202 is radially fixed and circumferentially surrounds and presses the side surface 101, and sufficient static friction force is generated between the pressed guard plate 202 and the side surface 101 to axially fix the guard plate 202 and the side surface 101.

Specifically, the side surface of the guard plate 202 is further provided with a plurality of radially arranged second through holes 2021, which are used for ventilation and heat dissipation of the side surface of the blank when the external device detects and processes the wall thickness of the side surface 101.

Compared with the prior art, the invention has the advantages that the thickness of the side wall can be measured while milling is performed by arranging the second through hole, ventilation and heat dissipation are realized through the through hole, and the problems of difficult thickness control and unsmooth heat dissipation in the processing of the side wall of the thin-wall part in the prior art are solved.

It should be noted that, the processing of thin-wall parts, especially the processing and heat dissipation of magnesium alloy parts, is always a key problem, and excessive heat accumulation can cause softening deformation and even burning of magnesium alloy. Magnesium alloy is a few metals which can react with nitrogen and oxygen in air at the same time, and the temperature control is particularly important during processing.

Preferably, the guard plate 202 is formed by axially splicing two guard plate units, and a connecting structure 205 with adjustable connecting gaps is arranged at the joint of the two guard plate units, so that the guard plate 202 can be matched with thin-wall part blanks with different outer diameters, the pressing degree of the guard plate 202 and the side face 101 is adjusted, and when the pressing force is enough, the guard plate 202 and the side face 101 generate enough static friction force to realize the axial fixation of the guard plate 202.

To achieve machining of the first recess 1013 on side 101, the height of the shield 202 is lower than the height of the thin-walled part blank.

Specifically, the milling cutter machines the first recess 1013 from outside to inside through the gap between the shield 202 and the first platen 201.

Preferably, the wall thickness of the shield 202 is greater than the wall thickness of the thin-walled part blank.

It should be noted that, the guard plate 202 is radially fixed by the first tie rod 204 and circumferentially surrounds and is pressed with the side 101, meanwhile, the wall thickness of the guard plate 202 is far greater than that of the thin-wall part blank, so that the rigidity of the side surface of the thin-wall part blank is improved, and when the milling cutter is used for machining the first groove 1013, the guard plate 202 provides circumferential supporting force for the side surface 101, and the supporting force is opposite to the force application direction of the milling cutter, so that the thin-wall part blank is stable and is not easy to vibrate or deform from outside to inside.

On one hand, the side face 101 is in a circular arch shape in the radial direction, so that the force applied by the milling cutter can be effectively dispersed, on the other hand, the guard plate 202 provides circumferential supporting force for the side face 101, and the guard plate 202 uniformly applies force on each point of contact with the side face 101, so that the side face deformation of the thin-wall part blank caused by local stress concentration in the region rotated by 90 degrees relative to the force application point of the milling cutter can be prevented.

Compared with the prior art, the guard plate 202 is arranged around the side surface of the thin-wall part blank, and can provide supporting force for two radial directions when the side surface of the thin-wall part blank is milled, so that vibration and deformation in the two radial directions are reduced.

Specifically, the first pull rod is detachably fixedly connected with the first pressing plate and the first bottom fixing piece.

Preferably, the connecting area of the first pull rod and the first pressing plate as well as the first bottom fixing piece is provided with threads, and the first pull rod is fixedly connected with the first pressing plate and the first bottom fixing piece by means of nuts matched with the threads.

Preferably, the first pull rod is arranged symmetrically relative to the center of the axis of the thin-wall part, and provides uniform pressure for the thin-wall part in the radial direction.

Specifically, regarding the turning mold, the turning mold is used for machining an end surface provided with an annular groove, and is fixedly connected with the first end surface and the second end surface of the thin-wall part at the same time, so that the thin-wall part is fixed on the turning mold.

Specifically, as shown in fig. 6 and 7, the turning mold further comprises a second pressing plate 307 and a second bottom fixing member 303, one end of the external supporting structure 301 is fixedly connected with the second bottom fixing member 303, the other end of the external supporting structure is in press fit connection with the outer side face of the second pressing plate 307, the inner side face of the second pressing plate 307 is in press fit connection with the outer side face of the second end face 103, and the external supporting structure 301 provides a tightening force for tightening the press fit between the second pressing plate 307 and the second bottom fixing member 303 for the thin-wall part through the second pressing plate 307.

Meanwhile, one side of the inner supporting structure 305 is connected with the inner side of the second end face 103 in a pressing mode, the other side of the inner supporting structure 305 is fixedly connected with the second bottom fixing piece 303, and the inner supporting structure 305 and the second bottom fixing piece 303 provide supporting force for the second end face 103 from the inside to the outside of the thin-wall part.

Specifically, the second end surface 103 partially coincides with the press-fit area of the second pressing plate 307, and the annular center edge of the second end surface 103 is provided with an area which is not blocked by the second pressing plate 307 and is used for processing the annular groove 1031.

Alternatively, the inner support structure 305 is fully coincident with the region of the second platen 307 for machining the annular groove 1031, the inner support structure 305 providing support to the machining region of the annular groove 1031 from inside the second platen 307.

The machining of the annular groove 1031 by the turning tool is performed from shallow to deep outside the second end face 103, at this time, the turning tool gives the second end face 103 a pressing force from outside to inside, and under the action of the pressing force, the second end face 103 also generates deformation or tremble, so that the machining precision is affected, and when the wall thickness of the thin-wall part is smaller, the influence of the deformation or tremble on the precision is larger, and the machining difficulty of the part is correspondingly increased.

Compared with the prior art, the internal support structure and the external support structure are arranged, the second pressing plate is used for providing the force for tightening and pressing between the second pressing plate and the second bottom fixing piece for the thin-wall part, the internal support structure and the second bottom fixing piece are used for providing the supporting force from the inside to the outside of the thin-wall part for the second end face, the forces in the two opposite directions balance the stress of the second pressing piece, the second end face is fixed, the deformation and the vibration of the second end face during machining of the machining tool are reduced, and the machining precision is improved.

Specifically, in order to realize press-fit fixation of the thin-wall part during turning, as shown in fig. 7, the external support structure 301 is provided with a connecting pressing plate 3011, second pull rods 3013 and an external support rod 3012, the connecting pressing plate 3011 is provided with through holes, the second pull rods 3013 are in one-to-one correspondence with the through holes, one end of each second pull rod 3013 penetrates through each through hole and is fixedly connected with the connecting pressing plate 3011, the other end of each second pull rod 3013 is fixedly connected with the second bottom fixing piece 303, a group of side surfaces penetrating through each through hole are arranged in parallel to the second pressing plate 307, and one side surface of the group of side surfaces is in press-fit abutting joint with the outer edge of the second pressing plate 307.

In practice, as shown in fig. 6, the second pressing plate 307 is an annular plate, the connecting pressing plate 3011 is a cuboid connecting block, and is pressed on the outer edge of the annular plate.

Optionally, a threaded structure is disposed at the end of the second pull rod 3013, and the second pull rod 3013 is fixedly connected to the connecting pressing plate 3011 by a nut after penetrating through the connecting pressing plate 3011.

It should be noted that, the connecting press plate 3011 is pressed against the outer edge of the annular flat plate of the second press plate 307, and is fixed to the second bottom fixing member 303 by the second tie rod 3013, so that the connection point between the second tie rod 3013 and the second press plate 307 is not coincident with the stress point between the connecting press plate and the second press plate 307, and the connecting press plate is subjected to a reverse stress while pressing the second press plate 307, so that the pressing and fixing manner between the connecting press plate 3011 and the second press plate 307 is easy to loosen.

Further, in order to solve the problem that the connecting pressing plate 3011 and the second pressing plate 307 are fixed by pressing and are easy to loosen and fall off, the outer supporting structure 301 is provided with an outer supporting rod 3012, one end of the outer supporting rod 3012 is fixedly connected with the connecting pressing plate 3011, the other end of the outer supporting rod 3012 is fixedly connected with the second bottom fixing piece 303, and the outer supporting rod 3013 is far away from the thin-wall part.

Compared with the prior art, the invention can realize stable lamination and fixation of the corners of the thin-wall part by arranging the connecting pressing plate 3011, the external supporting rod 3012 and the second pull rod 3013 on the external supporting structure 301, and does not need to adopt a long connecting pressing plate passing through the center area of the second end surface like the prior art, thereby improving the defect that the thin-wall part fixing die in the prior art interferes with the lathe tool processing.

Specifically, to realize the inner support of the second end surface 103, the inner support structure 305 is provided with an inner support plate 3051 and an inner support rod 3052, the inner support plate 3051 is in a ring shape and is coaxially matched with the second end surface 103, the inner side provides the second end surface 103 with a support force opposite to the pressing force of the connecting pressing plate 3011, one end of the inner support rod 3052 is fixedly connected with the inner support plate 3051, the other end of the inner support rod 3052 is fixedly connected with the second bottom fixing piece 303, and the inner support plate 3051 is provided with a support force opposite to the pressing force of the connecting pressing plate 3011 from inside to outside.

Optionally, the inner support plate 3051 is completely overlapped with the processing area of the annular groove 1031, so as to provide a supporting force opposite to the pressing force of the connecting pressing plate 3011 for processing the annular groove 1031, and thus, the deformation and vibration generated by processing the groove of the thin-walled workpiece can be greatly improved.

On the other hand, the invention provides a processing method of a large magnesium alloy thin-wall part with an annular groove on the end surface, which uses the processing die of the magnesium alloy thin-wall part with the annular groove on the end surface, as shown in fig. 10, and comprises the following steps:

The method comprises the steps of 1, connecting the center of a positioning block which is symmetrical relative to the center of an axle center to serve as a reference positioning line of a hollow annular end face, obtaining a fitting image of a thin-wall part blank based on laser scanning fitting imaging, and correcting the reference positioning line based on the fitting image of the thin-wall part blank, wherein the thin-wall part blank is provided with a side face, a free end face without shielding and a hollow annular end face, and at least two positioning blocks which are symmetrical relative to the center of the axle center are arranged on the inner surface of the side face.

Specifically, the fitting image of the thin-wall part blank is obtained based on the fitting image of the part blank and the theoretical image of the thin-wall part blank, and the deviation of the fitting image of the thin-wall part blank and the theoretical image thereof in each radial section is judged:

If the deviation of each radial section is smaller than or equal to a first threshold delta ₁, the reference positioning line is not subjected to any adjustment, and the correction is completed;

If the deviation of each radial section is larger than a first threshold delta ₁, the position of the axial lead of the theoretical image of the thin-wall part blank is adjusted until the deviation of each radial section is smaller than or equal to a first threshold delta ₁, the position change value delta (x, y, z) of the axial lead of the part blank is recorded, the axial lead coordinates of the corrected part blank are obtained according to the delta (x, y, z) change in the same space coordinate system, and the connecting line of the center of the positioning block and the axial lead of the corrected part blank is used as a corrected reference positioning line.

When the method is implemented, the thin-wall part blank is a hollow thin-wall part blank with two end faces, which is obtained by casting, the end faces are fixed on a rotary platform and can freely rotate around an axle center during processing, and the two end faces are arranged in parallel to a radial plane.

In the implementation, the positioning blocks and the thin-wall part blank are cast and formed in a die, and can be of a structure which is regular in shape and convenient to find the center, such as a cuboid, and the positioning blocks can be provided with a plurality of groups which are symmetrical to the center of the shaft center.

It should be noted that, the setting precision of the positioning block on the thin-wall part blank meets the requirement of preliminary alignment, so that a processor can roughly judge the position of the datum line, the rotation angle of the thin-wall part blank is convenient to adjust, and the initial processing position of the thin-wall part blank is close to the processing area.

The thin-wall part blank obtained by casting has the phenomenon of uneven wall thickness on the side surface, which is not an ideal state with even wall thickness, and if the thin-wall part blank is processed by the original design axis, products with uneven wall thickness are necessarily obtained, so that the axis position of the thin-wall part blank needs to be corrected, and the thin-wall part blank can be processed by rotating the position as the axis to obtain the products with even wall thickness.

When the method is implemented, the space coordinate system usually adopts the axial direction of the thin-wall part as a coordinate axis, and the radial direction is the plane where the other two coordinate axes are located; the laser scanning fitting imaging analysis software can display a fitting image of the part blank and a theoretical image of the thin-wall part blank at the same time, calculate non-coincident areas of the fitting image and the theoretical image, give different color marks, visually acquire radial plane deviations of the thin-wall part through the color marks, adjust the axial lead position of the fitting image of the part blank, change the color marks of the radial plane deviations, screen out the position with the minimum radial plane deviations, take the position as the corrected axial lead position of the part blank, calculate position change values delta (x, y, z), obtain the corrected axial lead position of the part blank after the axial lead of the part blank is changed according to delta (x, y, z), select any positioning block in a group of positioning blocks which are symmetrical relative to the axial lead center, connect the positioning block center and the corrected axial lead of the part blank in a radial plane, take the connecting line of the positioning blocks and the corrected axial lead as the corrected reference positioning line, and finish the correction of the reference positioning line.

And 2, performing vertical lathe processing on the outer circles of the two end faces and the side faces of the thin-wall part blank subjected to reference positioning line correction, wherein the vertical lathe processing leaves a margin.

The three-jaw clamp is used for fixing the thin-wall part blank by the inner part of the thin-wall part blank, the free end face of the thin-wall part blank is fixed on the rotary workbench, the hollow annular end face is arranged near the turning tool end, and the turning tool is turned from the hollow annular end face to the free end face to face the two end faces and the side excircle of the thin-wall part blank.

In implementation, as shown in fig. 8, a part blank is fixed on a rotary workbench 4 by using a three-jaw clamp 5, so that the part blank can rotate around a machine tool working platform 6 in the radial direction, and a machining tool 7 finishes excircle machining of a side face 101, a second end face 103 and a first end face 102 of a thin-wall part, wherein the machine tool working platform 6 is a vertical lathe working platform, and the machining tool 7 is a vertical lathe machining tool.

It should be noted that the three-jaw clamp is an internal fixing clamp commonly used for lathes, and is provided with three jaw heads, so that the distance between the three jaw heads can be adjusted, and the hollow parts with different inner diameters can be clamped and fixed from the inside of the hollow parts.

The allowance for the vertical lathe machining described herein means that the vertical lathe machining is not finished to the size of the molding assembly, and that there is an allowance for further vertical lathe machining.

The axial lead of the thin-wall part blank subjected to the machining and rotation of the reference positioning line is the corrected position, the side surface of the thin-wall part blank obtained by the machining and rotation of the axial lead has more uniform wall thickness, the cross section shape of the part blank after the vertical lathe machining is changed compared with that of the original thin-wall part blank, the wall thickness is uniform, and the cross section center of the part blank is positioned on the corrected axial lead.

And 3, carrying out milling machine processing on the side surface of the thin-wall part blank processed by the vertical lathe based on the corrected reference positioning line, wherein a milling mold is provided with a guard plate which is circumferentially attached and fixed with the outer side of the side surface of the thin-wall part blank, the milling machine processing leaves allowance, two reference holes are dispersedly arranged in an outer edge non-processing area of the free end surface of the thin-wall part blank relative to the axial lead, and the center point of each reference hole is collinear with the corrected reference positioning line.

The milling die for machining the side inner wall of the thin-wall part is fixed by the outer part of the thin-wall part blank, the hollow annular end face of the thin-wall part blank is fixed on a rotary workbench, the free end face is arranged near a milling cutter end, and the milling cutter performs milling on the side face of the thin-wall part blank from the inner side face to the outer side face.

In implementation, as shown in fig. 9, a part blank 1 is fixed on a rotary workbench 4 by using a milling die, so as to realize radial rotation around a machine tool workbench 6, one end of the milling die is provided with a first pressing plate 201 in press fit connection with a first end face 102, the other end of the milling die is provided with a first bottom fixing piece 203 in press fit connection with a second end face 103, a machining tool 7 penetrates into the thin-wall part to finish machining of a side face 101 from inside to outside, and allowance is machined and removed on a window 1011, and at the moment, the machine tool workbench 6 is a milling machine workbench, and the machining tool 7 is a milling tool.

The side surface of the part blank is provided with a plurality of windows, and the windows are required to be processed one by rotating the part blank, so that the rotation angle of the part blank and a rotating platform connected with the part blank is required to be determined when adjacent windows are processed.

The method comprises the steps of obtaining the connecting line between the window center and the axis of the side face of the part blank, further obtaining the included angle between the connecting line between the window center and the axis and the corrected reference positioning line, and calculating the rotation angle of the part blank and the rotation platform connected with the part blank when the adjacent window is processed according to the included angle.

The method comprises the steps of taking a machining datum line as an initial position when the machining datum line is vertically placed, determining an included angle between a connecting line of the center of a window and the axis of a part blank and the machining datum line, further determining the rotation angle alpha of the part blank and a rotating platform connected with the part blank to the machining datum line when the window rotates to the machining datum line, and determining the rotation angle of the part blank and the rotating platform connected with the part blank relative to the initial position when the adjacent window is machined based on the alpha of the adjacent window.

Specifically, on the corrected reference positioning line, two reference holes (not shown in the figure) are arranged in a dispersed manner relative to the axis in the outer edge non-processing area of the hollow annular end face of the thin-wall part blank.

The term "allowance for milling" as used herein means that the milling is performed to the size of the molded component, and that there is an allowance for further milling.

The positioning block is removed after the milling machine processing, and the corrected reference positioning line needs to be continuously transferred, so that the reference hole is set as a transfer medium of the reference positioning line.

Preferably, the reference hole is a target machining hole of the formed thin-wall part.

And4, stabilizing the thin-wall part blank processed by the milling machine.

Specifically, heating, air cooling, reheating and furnace cooling are carried out on the thin-wall part blank processed by the milling machine, and residual stress in the turning and milling processes is removed.

And 5, carrying out secondary vertical lathe processing on the outer circles of the two end faces and the side faces of the thin-wall part blank subjected to the stabilization treatment, wherein a margin is reserved in the secondary vertical lathe processing.

As shown in fig. 8, the part blank 1 is fixed on the rotary workbench 4 by using the three-jaw clamp 5, so as to realize radial rotation around the machine tool workbench 6, and the machining tool 7 finishes the excircle machining of the side face 101, the second end face 103 and the first end face 102 of the thin-wall part, wherein the machine tool workbench 6 is a vertical lathe workbench, and the machining tool 7 is a vertical lathe machining tool.

And 6, carrying out secondary milling machine processing on the thin-wall part blank processed by the secondary vertical lathe based on the reference hole, wherein a milling mold for the secondary milling machine processing is provided with a guard plate which is circumferentially attached and fixed with the outer side of the side surface of the thin-wall part blank, and the secondary milling machine processing leaves a margin.

In implementation, as shown in fig. 9, a part blank is fixed on a rotary workbench 4 by using a milling die, so as to realize radial rotation around a machine tool workbench 6, one end of the milling die is provided with a first pressing plate 201 in press fit connection with a first end face 102, the other end of the milling die is provided with a first bottom fixing piece 203 in press fit connection with a second end face 103, a machining tool 7 penetrates into the thin-wall part to finish machining of a side face 101 from inside to outside, and allowance is machined and removed on a window 1011, and at the moment, the machine tool workbench 6 is a milling machine workbench, and the machining tool 7 is a milling tool.

Specifically, a straight line where the connecting line of the central point of the reference hole is located is used as a reference positioning line for the second milling machine processing.

The method comprises the steps of marking a connecting line of a center point of a reference hole by using marking equipment, then using the connecting line as a reference positioning line for processing by a second milling machine, obtaining connecting lines of a window center and an axis line on the side face of a part blank, further obtaining an included angle between the connecting line of the window center and the axis line and the reference positioning line for processing by the second milling machine, taking the vertical positioning line as an initial position, determining the included angle between the connecting line of the center of the window and the axis of the part and the processing reference line, further determining the angle alpha of the part blank and a rotating platform connected with the part blank to the processing reference line, and determining the rotating angle of the part blank and the rotating platform connected with the part blank relative to the initial position when processing the adjacent window based on the alpha of the adjacent window.

And 7, based on the datum point and the turning mold for machining the thin-wall end face provided with the annular groove, performing third vertical turning on the thin-wall part blank machined by the second milling machine, machining the outer circle of the thin-wall part blank to the target size, and obtaining the annular groove of the central annular end face.

The turning mold for machining the thin-wall end face provided with the annular groove is used for fixing the thin-wall part blank from the inside and the outside of the thin-wall part blank, the free end face of the thin-wall part blank is fixed on a rotary workbench, the hollow annular end face is arranged near a turning tool end, and the turning tool is turned from the hollow annular end face to the free end face to face the two end faces and the side excircle of the thin-wall part blank.

In implementation, as shown in fig. 6 and 7, the turning mold comprises a second pressing plate 307, an outer supporting structure 301, an inner supporting structure 305 and a second bottom fixing member 303, wherein one end of the outer supporting structure 301 is fixedly connected with the second bottom fixing member 303, the other end of the outer supporting structure 301 is in press fit connection with the outer side surface of the second pressing plate 307, the inner side surface of the second pressing plate 307 is in press fit connection with the outer side surface of the second end surface 103, the outer supporting structure 301 and the second pressing plate 307 provide tightening and press fit force between the second pressing plate 307 and the second bottom fixing member 303 for the second end surface 103 and the thin-wall part, one side of the inner supporting structure 305 is in press fit connection with the inner side of the second end surface 103, the other side of the inner supporting structure 305 and the second bottom fixing member 303 provide support force from the inner side of the thin-wall part to the outer side of the second end surface 103.

When the turning tool is used, the inner edge of the center of the central annular end face is machined from shallow to deep, and the annular groove of the central annular end face is obtained.

And 8, carrying out third milling machine processing on the thin-wall part blank subjected to third vertical turning processing based on the reference hole, wherein a milling die for the third milling machine processing is provided with a guard plate which is circumferentially attached and fixed with the outer side of the side surface of the thin-wall part blank, the milling machine processing leaves allowance, and the third milling machine processing is used for processing a window of the side surface of the thin-wall part blank to a target size.

Specifically, a straight line where the connecting line of the central point of the reference hole is located is used as a reference positioning line for the third milling machine processing.

The method comprises the steps of marking a connecting line of a center point of a reference hole by using marking equipment, then using the connecting line as a reference positioning line for processing by a third milling machine, obtaining connecting lines of a window center and an axis line on the side surface of a part blank, further obtaining an included angle between the connecting line of the window center and the axis line and the reference positioning line for processing by the third milling machine, taking the vertical positioning line as an initial position, determining the included angle between the connecting line of the center of the window and the axis of the part and the processing reference line, further determining the rotation angle alpha of the part blank and a rotation platform connected with the part blank to the processing reference line, and determining the rotation angle of the part blank and the rotation platform connected with the part blank relative to the initial position when processing the adjacent window based on the alpha of the adjacent window.

Specifically, as shown in fig. 3, 4 and 5, a milling die is fixedly connected with a first end face 102 and a second end face 103 of a thin-wall part, one end of the milling die is provided with a first pressing plate 201 in press fit connection with the first end face 102, the other end of the milling die is provided with a first bottom fixing piece 203 in press fit connection with the second end face 103, meanwhile, the circumferential outer side edge of the first pressing plate 201 is fixedly connected with the circumferential outer side edge of the first bottom fixing piece 203 through a first pull rod 204, the first bottom fixing piece 203 is fixedly connected with a machine tool platform, and a fastening force is provided along the direction of the first pull rod 204 by the first pull rod 204, so that press fit fixation of the thin-wall part on the machine tool platform is realized.

The milling die is provided with a guard plate 202 for limiting radial vibration of the thin-wall part on the side face 101 of the thin-wall part, the guard plate 202 circumferentially surrounds the side face 101 and is provided with a first through hole 2022, the first through hole 2022 is provided with a first pull rod 204 in a penetrating mode, the first pull rod 204 circumferentially arranged along the side face 101 enables the guard plate 202 to circumferentially surround and be attached to the side face 101, and deformation or vibration of the thin-wall part radially outwards is limited when the inner wall of the side face 101 is processed by a milling tool.

The milling machine tool machines the side face 101 of the thin-walled part from inside to outside, applies a radially outward force to the side face 101, and easily causes deformation or chatter of the side face 101, and when the wall thickness of the machined blank becomes thin, the adverse effect of deformation or chatter on the machining accuracy is further increased.

Compared with the prior art, on one hand, the invention adopts the special vertical lathe processing die and milling processing die to process the thin-wall part with the annular groove on the end face, adopts the processing mode of rough processing, semi-finishing and finishing, reduces the deformation and mechanical damage caused by the accumulated stress of the thin-wall material, and improves the processing precision; the invention adopts a vertical lathe processing die to gradually thin the outer circle of the side wall of the thin-wall part, the rigidity of the side wall is gradually weakened, a guard plate is arranged on the milling processing die in the subsequent milling processing, the rigidity of the side surface of a blank of the thin-wall part is improved, the guard plate can provide supporting force for two radial directions when the blank of the thin-wall part is milled, thereby reducing vibration and deformation in two radial directions, and simultaneously, the rigidity of the side wall of the thin-wall part is reduced to prevent the side wall from deforming during vertical lathe processing.

On the other hand, the first pressing plate, the first bottom fixing piece, the first pull rod and the guard plate are arranged in the milling die, so that the pressing and fixing of the thin-wall part is realized, meanwhile, the adverse effect of tremble on the machining precision during side machining is greatly reduced, and the defects that tremble is easy to occur and the machining precision is poor during the side milling of the thin-wall part in the prior art are overcome.

In addition, the invention adopts the laser scanning imaging technology to preliminarily judge the wall thickness condition of each section of casting, determines the correction position of the rotating axis, adjusts and coordinates the wall thickness size of each processing part based on the corrected axis to the processing datum line, ensures that the wall thickness borrowing amount of the part before processing is uniform as much as possible, ensures that the processing allowance of each surface is uniform, ensures that the wall thickness uniformity meets the requirement, and simultaneously greatly reduces the workload of machine tool alignment and zero setting in the subsequent working procedure while ensuring the datum line marking precision.

In addition, the positioning block is arranged on the inner side surface of the cast thin-wall part blank, the radial plane connecting line of the center of the positioning block is used as a reference in the first vertical lathe process, the workload of machine tool alignment and zero setting in the subsequent working procedure can be greatly reduced on the basis of meeting the precision requirement, the positioning block and the rotation axis correction position are further utilized to determine a processing reference positioning line, a reference hole is further arranged on the processing reference positioning line to serve as a transmission medium of an original reference, the continuation of the reference is ensured, and the processing precision is improved.

In addition, the deformation and precision errors in the casting process of the blank after the positioning datum line and the axis are corrected are removed through vertical lathe machining, so that the rotation axis of the blank coincides with the geometric center of the end face of the blank, and the datum is provided for the next machining by combining the positioning datum line.

The fitting image of the thin-wall part blank is obtained based on laser scanning fitting imaging in the step 1, and the method specifically comprises the steps of using sensors densely distributed on the inner surface and the outer surface of the thin-wall part blank as data sampling points, obtaining coordinates of the sensors in a space coordinate system by using laser scanning, and fitting a three-dimensional image of the thin-wall part blank according to the space coordinate information of the sensors.

Specifically, the correcting the reference positioning line based on the fitting image of the thin-wall part blank in the step 1 includes:

S101, utilizing laser scanning fitting imaging software to coincide the axial leads of a fitting image of a part blank and a theoretical image of a thin-wall part blank, comparing the thicknesses of all areas of the radial section of the part blank, automatically acquiring deviation and carrying out color identification according to the deviation;

S102, if the deviation of each radial section is smaller than or equal to a first threshold delta ₁, no adjustment is performed, and the reference positioning line is corrected;

if the deviation of each radial section is larger than a first threshold delta ₁, adjusting the position of the axis of the theoretical image of the thin-wall part blank until the deviation of each radial section is smaller than or equal to a first threshold delta ₁, and recording the position change value delta (x, y, z) of the axis of the space coordinate system;

S103, constructing a space coordinate system which is the same as a fitting image of the part blank and a theoretical image of the thin-wall part blank, and acquiring the axial lead coordinate of the corrected part blank according to delta (x, y, z) change in the coordinate system;

And S104, connecting the center of any positioning block with the axial lead of the corrected part blank in the radial plane of the positioning block center of the part blank, and taking the connecting line of the center of any positioning block and the axial lead of the corrected part blank as a corrected reference positioning line to finish the correction of the reference positioning line.

Preferably, the first threshold δ ₁ is 0.02mm.

The determination of the first threshold δ1 is related to the accuracy of the dial indicator itself, and the first threshold δ ₁ <0.02mm is beyond the accuracy range of the dial indicator.

Specifically, the vertical lathe processing in the step 2 includes the following steps:

S201, selecting 1/4-1/2 of the machining amount of the fixed thin-wall part blank from the vertical lathe, and performing trial machining to obtain a trial machining blank sample;

s202, detecting the eccentricity of the rotation of the sample of the trial-processed blank around the axis of the corrected part blank;

S203, judging the eccentricity;

if the eccentricity is smaller than a second threshold delta ₂, turning;

If the eccentricity is greater than the second threshold delta ₂, repeating S101-S104 to correct the axial lead of the part blank again until the eccentricity is less than the second threshold delta ₂.

The eccentricity is checked by a dial indicator, and the method comprises the following steps of fixing the fixed end of the dial indicator on a machine tool platform, enabling the test end to be in contact with the side face of the part blank until an indication number is reached, and recording the change of the indication number of the dial indicator in the process of rotating the part blank for one circle.

Specifically, the eccentricity is evaluated by using the change eta of the indicator index of the dial indicator, wherein eta is satisfied by eta=S _max-S_min, S _max is the maximum value of the indicator index of the dial indicator, and S _min is the minimum value of the indicator index of the dial indicator.

Optionally, the second threshold δ ₂ is set to 0.02mm.

The determination of the second threshold value δ ₂ is related to the accuracy of the dial indicator itself, and the second threshold value δ ₂ is less than 0.02mm and exceeds the accuracy range of the dial indicator.

In order to meet the requirement of magnesium alloy processing, the feeding amount of a part blank is 0.4 mm/r-0.6 mm/r in the first turning, is lower than 0.4mm/r, is easy to cause the deformation of the magnesium alloy and even spontaneous combustion due to local overheating, is higher than 0.6mm/r, and is difficult to meet the precision requirement.

In order to improve the local heat dissipation, air-cooled air flow of 0.6-0.8 MPa is given during the processing of a part blank.

Compared with the prior art, the invention adopts air-cooled air flow of 0.6-0.8 MPa to cool, solves the problem of local heat dissipation, is beneficial to further reducing the feed quantity and improving the processing precision and the processing safety.

In order to reduce the deformation during processing, the cutting depth of the part blank is 0.5-2, and the cutting depth of the part blank is more than 2, so that the part blank is easy to deform under the fixation of a common three-jaw clamp.

Specifically, the processing amount of the vertical lathe in the step 2 is 2-4 mm.

Preferably, the processing amount of the vertical lathe processing in the step 2 is 3mm.

Specifically, step 3, performing milling machine processing, by obtaining an included angle between a part blank side window center, an axis line and a corrected reference positioning line, and calculating a rotation angle of the part blank and a rotation platform connected with the part blank when processing an adjacent window by using the included angle, specifically including:

S301, connecting the center of the window with the axis of the part blank in a radial plane where the window is positioned, acquiring an included angle alpha between the connecting line and a machining datum line through angle measuring equipment, and numbering the window as a first window according to the adjacent sequence of the window;

S302, calculating a difference delta alpha between any adjacent window and a machining datum line, and taking the difference delta alpha as a rotation angle of a part blank and a rotating platform connected with the part blank when the adjacent window is machined, wherein delta alpha meets the requirements that delta alpha = alpha _k-α_k-1, k is less than or equal to n, k represents a window sequence number, and alpha _k is an included angle between a connecting line of the center of the kth window and the axis of the part blank and the machining datum line in a radial plane where the center of the kth window is located.

Specifically, when adjacent window processing, the rotation angle of part blank and rotary platform who connects adjusts, realizes adjusting through rotary platform from taking the angle scale.

Specifically, the reference hole in step 3 is obtained by using a machine tool tapping device, and the positioning pin is inserted to correct the reference hole, including:

s311, setting a first coordinate axis in the direction vertical to a horizontal plane, taking the rotation axis of a machine tool rotation platform as a second coordinate axis, setting a third coordinate axis in the direction vertical to the first coordinate axis and the second coordinate axis in the horizontal plane, and constructing a space coordinate system;

S312, selecting a locating pin of one of the reference holes as a first locating pin, arranging a dial indicator on a main shaft of the machine tool to be in contact with the highest position of the side surface of the first locating pin, and recording the reading of the dial indicator;

S313, selecting a locating pin of another reference hole as a second locating pin, rotating 180 degrees by utilizing the self scale of a machine tool rotating platform, keeping the coordinates of a machine tool spindle on a first coordinate axis and a second coordinate axis unchanged at the highest position of the side surface of the second locating pin, and recording the reading of a dial indicator;

S314, correcting the reference hole based on two readings of the dial indicator;

If the difference value of the readings of the dial indicator is smaller than a third threshold delta ₃, judging that the setting of the reference hole meets the requirement;

If the difference value of the two readings of the dial indicator is larger than a third threshold delta ₃, reaming is carried out on the original reference hole based on the corrected reference positioning line, and the matched positioning pins are selected to repeat S312-S313 until the difference value of the two readings of the dial indicator is smaller than the third threshold delta ₃.

Specifically, the accuracy of the reference hole setting is evaluated by using the change eta of the dial indicator index, eta is satisfied that eta=S _max-S_min, wherein S _max is the maximum value of the dial indicator index of two dial indicator readings, and S _min is the minimum value of the dial indicator index of two dial indicator readings.

Optionally, the third threshold δ ₃ is set to 0.02mm.

The determination of the third threshold value δ ₃ is related to the accuracy of the dial indicator itself, and the third threshold value δ ₃ is less than 0.02mm and exceeds the accuracy range of the dial indicator.

Specifically, reaming the original reference hole based on the corrected reference positioning line comprises the steps of carrying out reaming after repositioning the circle center of the reference hole after reaming on the corrected reference positioning line, wherein the diameter of the reference hole for reaming is larger than that of the original reference hole, and the reference hole after reaming completely covers the original reference hole area, so that errors caused by the position setting deviation of the original reference hole are eliminated.

It should be noted that, the distance between the center of the reference hole and the corrected reference positioning line can be adjusted according to actual needs, so that when the dial indicator is read in steps S312-S313, the coordinate reading of the third coordinate axis parallel to the direction of the corrected reference positioning line is not required.

Specifically, the milling machine in the step 3 is used for processing 1 mm-5 mm in processing amount.

Preferably, the machining amount of the milling machine in the step 3 is 2 mm-3 mm.

Specifically, the determining the highest position of the pin side in S312 and S313 includes:

S321, setting a first coordinate axis in the direction vertical to a horizontal plane, setting a third coordinate axis in the direction vertical to the first coordinate axis and the second coordinate axis in the horizontal plane by taking the rotation axis of the machine tool rotation platform as a second coordinate axis, and constructing a space coordinate system by taking the center of the machine tool rotation platform as an origin;

S322, selecting a locating pin of one of the reference holes to insert a matched locating pin, arranging a dial indicator on a main shaft of a machine tool, contacting with a top area of one end of the side surface of the locating pin, displaying the coordinate of a first coordinate axis and the coordinate of a second coordinate axis of the main shaft of the machine tool unchanged, moving the main shaft of the machine tool parallel to a third coordinate axis, and keeping the display number of the dial indicator to be different from zero;

s323, the same method is used for obtaining the coordinates of the highest point at the other end of the side face of the positioning pin, comparing the coordinates of the highest points at the two ends, and taking the coordinate with the larger coordinate value of the first coordinate axis as the coordinate of the highest position of the side face of the pin.

It should be noted that, the pin generally selects a cylinder with smooth and flat side surface, which is limited by the punching precision of the reference hole, the flatness of the hole is poor, and the positioning pin may be out of level after installation and cannot be further used for correcting the reference hole.

Further, in order to correct the longitudinal flatness of the reference hole opening, the flatness correction of the reference hole opening is further included between S311 and S312:

S324, comparing the highest point coordinates (x ₁,y₁,z₁) and (x ₂,y₂,z₂) of the two ends obtained in the two steps S322 and S323 to obtain coordinate differences Deltax, deltay and Deltaz of each coordinate axis, wherein Deltax= |x ₁-x₂|,△y＝|y₁-y₂|,△z＝|z₁-z₂ |;

If the delta x, the delta y and the delta z are smaller than a fourth threshold delta ₄, judging that the flatness of the open hole of the reference hole meets the requirement;

If any numerical value of Deltax, deltay and Deltaz is larger than a fourth threshold value Delta ₄, reaming is carried out on the original reference hole based on the corrected reference positioning line, and S322-S323 are repeated by using matched positioning pins until Deltax, deltay and Deltaz are smaller than the fourth threshold value Delta ₄.

Optionally, the fourth threshold δ ₄ is related to machine tool machining accuracy.

Compared with the prior art, the method has the advantages that according to the difference of machining positions, the arc surface is machined by dividing the arc surface by adopting the dividing regions, and then machining is performed by planning machining tracks in each dividing region one by one in a window mode, instead of fixing a thin-wall part blank, the movement of a cutter is controlled, the movement displacement of the cutter is reduced, machining tremble caused by overlong overhanging of another cutter is avoided, machining precision is guaranteed, and machining efficiency is improved.

Specifically, the stabilizing treatment process in step 4 further reduces residual stress in the preprocessing process, and includes the following steps:

S401, performing heat treatment for 2-6 hours at 120+/-10 ℃, and then performing air cooling to cool to room temperature;

s402, heat treatment is carried out for 2-6 hours at the temperature of 120+/-10 ℃, and then the furnace is cooled to room temperature.

The thermal stress continuously generated in the normal temperature-air cooling-normal temperature-furnace following cooling process is overlapped with the original residual stress, and the original residual stress is reduced due to plastic deformation caused by exceeding the yield strength of the material, so that the plasticity and the workability of the material of the cylindrical part are further improved.

Specifically, the step S401 is performed with air cooling to more rapidly realize superposition of external surface thermal stress and original residual stress and plastic deformation, the step S402 is performed with furnace cooling to more slowly reduce the thermal stress generated by air cooling on the external surface and the internal surface of the part blank, and the effect of reducing the stress generated by rough machining is realized as a whole.

The first vertical lathe machining and the milling machine machining belong to rough machining processes, and because the allowance for removal is large and the accumulated stress in the machining process is large, stabilization treatment is needed to remove the accumulated stress, the allowance for removal of the second vertical lathe machining, the second milling machine machining, the third vertical lathe machining and the third milling machine machining is small, and the machined blank piece is thinner, so that the accumulated stress is not easy to accumulate.

Specifically, in the second turning in the step 5, in order to meet the requirement of magnesium alloy processing, the feeding amount of a part blank is 0.4 mm/r-0.6 mm/r, is lower than 0.4mm/r, the magnesium alloy is easy to deform and even self-ignite due to local overheating, and is higher than 0.6mm/r, so that the precision requirement is difficult to meet.

Specifically, in the step 5, the allowance is reserved in the second vertical lathe processing, the outer circle is not processed to be of a forming size, and the processing amount of the second vertical lathe processing is 1-3 mm.

Preferably, the processing amount of the second vertical lathe processing in the step 5 is 2mm.

Specifically, step 6, performing a second milling machine process, by obtaining an included angle between a side window center of the part blank, a line connecting an axis and a corrected reference positioning line, and calculating a rotation angle of the part blank and a rotation platform connected with the part blank when processing an adjacent window by using the included angle, specifically including:

S601, connecting the center of a window with the axis of a part blank in a radial plane where the window is positioned, acquiring an included angle alpha between the connecting line and a machining datum line through angle measuring equipment, and numbering the window as a first window according to the adjacent sequence of the window;

S602, calculating a difference value delta alpha of an included angle between any adjacent window and a processing datum line, and taking the difference value delta alpha as a rotation angle of a part blank and a rotation platform connected with the part blank when the adjacent window is processed, wherein delta alpha meets the condition that delta alpha = alpha _k-α_k-1, and k is less than or equal to n.

When the window processing method is implemented, the angle scale of the rotating platform is recorded during the processing of the previous window, and the angle scale of the rotating platform is rotated by delta alpha, so that the window to be processed is positioned at the processing position of the previous window.

And 7, performing third vertical lathe processing to process the outer circle of the thin-wall part blank to a target size and obtain an annular groove of a central annular end face, wherein the third vertical lathe processing comprises the following steps:

s701, fixing the free end face of a thin-wall part blank on a rotary workbench by using the turning mold for machining the thin-wall end face provided with the annular groove, wherein the hollow annular end face is arranged near a turning tool end;

S702, machining the side excircle of the thin-wall part blank to a target size by using a turning tool;

S703, machining the inner edge of the central annular end face of the thin-wall part blank by using a turning tool to obtain an annular groove.

Specifically, S701, fixing the free end surface of the thin-walled part blank to the rotary table, includes:

S7011, one end of the external supporting structure is fixedly connected with the second bottom fixing piece, and the other end of the external supporting structure is connected with the outer side surface of the second pressing plate in a pressing mode;

S7012, one side of the internal supporting structure is connected with the inner side of the second end surface in a pressing mode, and the other side of the internal supporting structure is fixedly connected with the second bottom fixing piece.

Compared with the prior art, the internal support structure and the external support structure are arranged in the turning mold, the second pressing plate provides the force for tightening and pressing the thin-wall part between the second pressing plate and the second bottom fixing piece, the internal support structure and the second bottom fixing piece provide the supporting force from the inside to the outside of the thin-wall part for the second end face, the forces in two opposite directions balance the stress of the second pressing piece, the second end face is fixed, the deformation and vibration of the second end face during the machining of the turning tool are reduced, and the machining precision is improved.

In order to meet the requirement of magnesium alloy processing, the feeding amount of a part blank is 0.2 mm/r-0.4 mm/r in the third turning, is lower than 0.2mm/r, is easy to cause the deformation of the magnesium alloy and even spontaneous combustion due to local overheating, is higher than 0.4mm/r, and is difficult to meet the precision requirement.

In order to improve the local heat dissipation, air-cooled air flow of 0.7-0.8 MPa is given during the processing of a part blank.

Compared with the prior art, the invention adopts air cooling air flow of 0.8-1.0 MPa to cool, increases air pressure, is beneficial to solving the problem of local heat dissipation, can reduce the feeding amount, and improves the processing precision and the processing safety.

In order to reduce the deformation during processing, the cutting depth of the part blank is 0.2-0.5, and the thickness of the part is reduced by the third time of turning, wherein the cutting depth of the part blank is less than or equal to 0.5, and meanwhile, the part blank is fixed by a turning die for processing the thin-wall end face provided with the annular groove, so that the deformation is avoided.

And 8, processing a window on the side surface of the thin-wall part blank to a target size by the third milling machine processing, wherein the third milling machine processing comprises the following steps:

S801, fixing a hollow annular end face of a thin-wall part blank on a rotary workbench by using the milling die for machining the side inner wall of the thin-wall part, and arranging the free end face near a turning tool end;

s802, connecting the center of the window with the axis of the part blank in a radial plane where the window is positioned, acquiring an included angle alpha between the connecting line and a machining datum line through angle measuring equipment, and numbering the window as a first window according to the adjacent sequence of the window;

S803, calculating a difference value delta alpha of an included angle between any adjacent window and a processing datum line, and taking the difference value delta alpha as a rotation angle of a part blank and a rotation platform connected with the part blank when the adjacent window is processed, wherein delta alpha meets the condition that delta alpha = alpha _k-α_k-1, and k is less than or equal to n.

S804, setting a machining area of a milling cutter as a horizontal plane below an axle center by taking a vertical state of a machining datum line as an initial position, rotating a rotating platform by alpha ₁ degrees to enable a connecting line of a first window and an axle center to be in the initial position, enabling a machining plane of the first window to be in a machining area of the milling cutter, and milling the first window to a target size;

S805, rotating the rotating platform by alpha ₂-α₁ degrees to enable the machining plane of the second window to be located in the machining area of the milling cutter, and milling the second window to the target size;

And S806, rotating the rotating platform by alpha ₃-α₂,…,α_n-α_n-1 degrees to enable the machining plane of the nth window to be located in a machining area of the milling cutter, milling the nth window to a target size, and finishing the third milling machine machining of the thin-wall part blank.

Specifically, S801 describes fixing a free end surface of a thin-walled part blank to a rotary table, including:

s8011, a first pressing plate of a milling mold is connected with a first end face in a pressing mode, and a first bottom fixing piece is connected with a second end face in a pressing mode;

s8012, fixedly connecting the circumferential outer edge of the first pressing plate and the corresponding position of the circumferential outer edge of the first bottom fixing piece through a first pull rod, and fixedly connecting the first bottom fixing piece with a machine tool platform;

And S8013, penetrating the first pull rod into a first through hole formed in the circumferential surrounding side surface, and enabling the first pull rod arranged along the side surface to circumferentially surround and attach the guard board to the side surface.

Compared with the prior art, the milling die has the advantages that the first pressing plate, the first bottom fixing piece, the first pull rod and the guard plate are arranged in the milling die, so that the pressing and fixing of the thin-wall part is realized, meanwhile, the adverse influence of tremble on the machining precision during side machining is greatly reduced, and the defects that tremble is easy to occur and the machining precision is poor in the side machining of the thin-wall part in the prior art are overcome.

The third milling process further comprises the step of detecting the wall thickness of each part of the side surface by using measuring equipment.

Meanwhile, the second through holes are formed in the guard plate in the radial direction, so that the thickness of the side wall can be measured during milling, ventilation and heat dissipation are achieved through the through holes, and the problems that in the prior art, the thickness control is difficult and the heat dissipation is not smooth during machining of the side wall of the thin-wall part are solved.

Specifically, as shown in fig. 3 and 4, a plurality of second through holes 2021 are provided on the side surface of the guard plate 202, and the external device detects the wall thickness at each point of the side surface 101 through the second through holes 2021.

In practice, the wall thickness at each point of the side 101 is detected using ultrasonic, laser or X-ray equipment.

The processing method of the magnesium alloy thin-wall part further comprises a step of checking crack damage of the thin-wall part after the step 8, specifically, the method of GJ/B1187A-2001 'ray detection' is used for detection, the acceptance standard is QJ20708 'rare earth heat-resistant cast magnesium alloy and I castings in casting specifications' are used for acceptance, and the selection method is X-ray fluorescence flaw detection.

The processing method of the magnesium alloy thin-wall part comprises a micro-arc oxidation treatment step of the surface of the magnesium alloy thin-wall part after the step of checking crack damage of the thin-wall part, specifically, a magnesium oxide layer with good heat resistance and hardness is generated on the surface of the magnesium alloy by utilizing a high-voltage arc, and the oxidation resistance, the surface hardness and the wear resistance of the magnesium alloy are improved.

The present invention is not limited to the above-mentioned embodiments, and any changes or substitutions that can be easily understood by those skilled in the art within the technical scope of the present invention are intended to be included in the scope of the present invention.

Claims

1. The processing die of the thin-wall part with the annular groove on the end face is characterized by comprising a milling die and a turning die;

the thin-wall part comprises a first end face, a second end face and a side face for connecting the first end face and the second end face, wherein the first end face is a free end face without shielding, and the second end face is a hollow annular end face;

The turning mold is used for turning the thin-wall end face of the thin-wall part, which is provided with the annular groove, and is provided with an outer supporting structure for pressing the outer part of the hollow annular end face of the thin-wall part and an inner supporting structure for supporting the inner part of the central annular end face of the thin-wall part, and the outer supporting structure and the inner supporting structure enable the thin-wall part to be kept stable during the annular groove machining;

the turning mold is fixedly connected with the first end face and the second end face of the thin-wall part at the same time, and the thin-wall part is fixed on the turning mold;

The turning mold further comprises a second pressing plate and a second bottom fixing piece, wherein one end of the external supporting structure is fixedly connected with the second bottom fixing piece, and the other end of the external supporting structure is connected with the outer side face of the second pressing plate in a pressing manner;

The external supporting structure is provided with a connecting pressing plate, a second pull rod and an external supporting rod; the connecting press plate is provided with through holes, the second pull rods are in one-to-one correspondence with the through holes, one ends of the second pull rods penetrate through the through holes and are fixedly connected with the connecting press plate, and the other ends of the second pull rods are fixedly connected with the second bottom fixing piece;

One end of the external support rod is fixedly connected with the connecting pressing plate, the other end of the external support rod is fixedly connected with the second bottom fixing piece, and the external support rod is arranged opposite to the second pull rod and far away from the thin-wall part;

one side of the inner supporting structure is connected with the inner side of the second end face in a pressing mode, and the other side of the inner supporting structure is fixedly connected with the second bottom fixing piece;

the milling die is fixedly connected with the first end face and the second end face of the thin-wall part at the same time, so that the thin-wall part is fixed on the milling die;

The milling die is characterized in that one end of the milling die is provided with a first pressing plate in pressing connection with the first end face, the other end of the milling die is provided with a first bottom fixing piece in pressing connection with the second end face, the milling die is also provided with a first pull rod, and the circumferential outer side edge of the first pressing plate is fixedly connected with the circumferential outer side edge of the first bottom fixing piece through the first pull rod.

2. The working mold according to claim 1, wherein the second end face partially coincides with the press-fit area of the second platen, and the annular center edge of the second end face is provided with an area which is not shielded by the second platen and is used for working the annular groove.

3. A method for machining a thin-walled part having an annular groove in an end face, characterized by using the machining die according to claim 1 or 2.