CN113909366A - Wall thickness control method for 2195 aluminum lithium alloy integral box bottom spinning part with phi of 3350mm - Google Patents
Wall thickness control method for 2195 aluminum lithium alloy integral box bottom spinning part with phi of 3350mm Download PDFInfo
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- 238000009987 spinning Methods 0.000 title claims abstract description 279
- 238000000034 method Methods 0.000 title claims abstract description 71
- 229910001148 Al-Li alloy Inorganic materials 0.000 title claims abstract description 65
- 239000001989 lithium alloy Substances 0.000 title claims abstract description 58
- JFBZPFYRPYOZCQ-UHFFFAOYSA-N [Li].[Al] Chemical compound [Li].[Al] JFBZPFYRPYOZCQ-UHFFFAOYSA-N 0.000 title claims abstract description 55
- 238000003825 pressing Methods 0.000 claims description 28
- 238000010438 heat treatment Methods 0.000 claims description 7
- 238000003754 machining Methods 0.000 claims description 5
- 239000000463 material Substances 0.000 claims description 5
- 238000002360 preparation method Methods 0.000 claims description 5
- FCVHBUFELUXTLR-UHFFFAOYSA-N [Li].[AlH3] Chemical compound [Li].[AlH3] FCVHBUFELUXTLR-UHFFFAOYSA-N 0.000 claims description 3
- 238000002156 mixing Methods 0.000 claims description 3
- 238000004528 spin coating Methods 0.000 claims 1
- 238000003860 storage Methods 0.000 abstract description 9
- 238000004519 manufacturing process Methods 0.000 abstract description 5
- 230000000694 effects Effects 0.000 description 13
- 238000013461 design Methods 0.000 description 11
- 235000015842 Hesperis Nutrition 0.000 description 5
- 235000012633 Iberis amara Nutrition 0.000 description 5
- 230000007547 defect Effects 0.000 description 5
- 238000003466 welding Methods 0.000 description 4
- 238000001125 extrusion Methods 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 229910000716 2195 aluminium alloy Inorganic materials 0.000 description 1
- 241000219112 Cucumis Species 0.000 description 1
- 235000015510 Cucumis melo subsp melo Nutrition 0.000 description 1
- 229910000733 Li alloy Inorganic materials 0.000 description 1
- FJJCIZWZNKZHII-UHFFFAOYSA-N [4,6-bis(cyanoamino)-1,3,5-triazin-2-yl]cyanamide Chemical compound N#CNC1=NC(NC#N)=NC(NC#N)=N1 FJJCIZWZNKZHII-UHFFFAOYSA-N 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000010791 quenching Methods 0.000 description 1
- 230000000171 quenching effect Effects 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
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- 230000011218 segmentation Effects 0.000 description 1
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D22/00—Shaping without cutting, by stamping, spinning, or deep-drawing
- B21D22/14—Spinning
- B21D22/16—Spinning over shaping mandrels or formers
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
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- B21D53/88—Making other particular articles other parts for vehicles, e.g. cowlings, mudguards
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Abstract
A wall thickness control method for a phi 3350mm integral box bottom spinning part, in particular to a wall thickness control method for a phi 3350mm2195 aluminum lithium alloy integral box bottom spinning part, which belongs to the technical field of manufacturing of storage box shells. Specifically, the phi 3350mm2195 aluminum lithium alloy integral box bottom spinning part enables the box bottom spinning part to be spun section by section and attached to a die section by section through accurately designing a forming gap, accurately designing and controlling a spinning pass and a strong-normal spinning stroke and adopting a forming process of alternately performing positive-reverse spinning and combining strong-normal spinning, so that the forming quality and the wall thickness precision of the box bottom spinning part are improved, the thickness difference of the same annular wall of the phi 3350mm2195 aluminum lithium alloy integral box bottom spinning part is less than or equal to 0.8mm, and the difference between the actually measured wall thickness value and the theoretical wall thickness value is less than or equal to 0.5 mm.
Description
Technical Field
The invention relates to a wall thickness control method for a spun and pressed piece at the bottom of an aluminum lithium alloy integral box, in particular to a wall thickness control method for a spun and pressed piece at the bottom of an aluminum lithium alloy integral box with phi of 3350mm2195, and belongs to the technical field of manufacturing of a shell of a storage box.
Background
High carrying efficiency and high reliability are the constant pursuits of large and ultra-large carrier rockets (the diameter is more than or equal to 3350mm) and other aerospace vehicles. The integral manufacturing (the welding seams are reduced or eliminated as much as possible) of the light-weight high-strength arrow body structural material and the structural member is an effective way for realizing the light weight and high reliability of the aerospace craft.
The bottom of the storage box is used as a key section of the rocket body structure and is closely related to the reliability of aircrafts such as a carrier rocket. At present, the tank bottoms of the storage tanks of the overseas phi 5000mm grade main flow carrier rockets are integrally formed, the tank bottom structures of the storage tanks of the carrier rockets in service and in research in China are all formed by welding melon petals, the length of welding lines of the tank bottoms is nearly 1km, and the reliability of the aircrafts such as the carrier rockets is severely restricted by the existence of a large number of welding lines.
In order to meet the requirements of large and ultra-large carrier rockets (the diameter is more than or equal to 3350mm) and other aerospace craft on high carrying efficiency and high reliability, the method provides requirements for a manufacturing technology of 2195 aluminum lithium alloy storage box hemisphere shells with the diameter phi of 3350 mm.
Aiming at the bottom structure of a large and ultra-large 2195 aluminum lithium alloy storage box with the inner diameter of more than or equal to phi 3350mm, good comprehensive mechanical properties are generally obtained by T6 heat treatment (solid solution-quenching-aging) after the forming, and the bottom structure is inevitably deformed in the T6 heat treatment process, particularly in the quenching stage; in addition, the box bottom structure undergoes large deformation in the forming process, large residual stress is accumulated in the box bottom structure, the internal stress state of the box bottom structure is further worsened in the heat treatment process, and local deformation of the box bottom structure is easily caused, so that the forming path of the box bottom structure of the large and ultra-large 2195 aluminum lithium alloy storage box generally comprises the steps of forming raw materials into a box bottom spinning part, and then processing and thinning the box bottom spinning part to form the integral spinning box bottom.
The mainstream manufacturing process is integral spinning forming aiming at the bottom structure of a large and ultra-large 2195 aluminum lithium alloy storage tank with the inner diameter of more than or equal to phi 3350 mm. The box bottom structure can improve the structural strength to the maximum extent in the integral spinning process, and can obtain better profile degree and dimensional accuracy.
Aiming at the bottom structure of a large and ultra-large 2195 aluminum lithium alloy integral spinning box with the inner diameter of more than or equal to phi 3350mm, the forming difficulty is mainly that the deformation resistance of the 2195 aluminum lithium alloy is large, so that the uniformity of the wall thickness of a spinning part in the same ring direction is poor; meanwhile, as the circumferential diameter of the spinning part is increased, the actual wall thickness at the corresponding position is greatly deviated from the theoretical wall thickness value, and the thinning effect is more obvious as the actual wall thickness is closer to the position of the large port part. The above conditions seriously worsen the wall thickness precision of the box bottom spinning and pressing piece, reduce the machining allowance of the inner and outer molded surfaces of the preset box bottom structure, increase the risk of the out-of-tolerance wall thickness of the box bottom structure, and even cause the condition that the wall thickness does not meet the technical/tactical indexes and the component is directly scrapped.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: the method for controlling the wall thickness of the phi 3350mm2195 aluminum lithium alloy integral box bottom spinning part overcomes the defects of the prior art, and enables a box bottom spinning part to be spun section by section and attached to a die section by section through accurately designing a forming gap, accurately designing and controlling a spinning pass and a strong-normal spinning pass and adopting a forming process of alternately performing forward-reverse spinning and combining strong-normal spinning, so that the forming quality and the wall thickness precision of the box bottom spinning part are improved, the same annular wall thickness difference of the phi 3350mm2195 aluminum lithium alloy integral box bottom spinning part is less than or equal to 0.8mm, and the difference between an actual measured wall thickness value and a theoretical wall thickness value is less than or equal to 0.5 mm.
The purpose of the invention is realized by the following technical scheme:
a wall thickness control method for a 2195 Al-Li alloy integral box bottom spinning part with a diameter of phi 3350mm comprises the following steps:
designing a forming clearance of a spinning and pressing piece at the bottom of a box
According to the external surface generatrix equation of the spinning core mold and a thermal expansion difference compensation formula, the forming clearance of a spinning part at the bottom of the box is designed, and meanwhile, in order to improve the mold sticking effect of the spinning part at the bottom of the box, the clearance design adopts negative deviation, as shown in a formula (1):
ti＝[t0Sinαi+Xi(T-T0)(M-N)]K……………(1)
in the formula: t is tiIs a half cone angleαiDesigning a gap at the position; t is t0The thickness of the spinning plate blank; alpha is alphaiIs a half cone angle; xiIs a half cone angle alpha of a core moldiAbsolute value of abscissa of position; t is the spinning deformation temperature; t is0Is at room temperature; m is the linear expansion coefficient of 2195 Al-Li alloy at the spinning deformation temperature; n is the linear expansion coefficient of the core mould material at the spinning deformation temperature; k is a negative offset coefficient and is 0.90-0.95.
The formula (1) is only suitable for the gap design in the strong-ordinary spin forming and die attaching stages, and the gap design value in the ordinary spin forming and die attaching stages is consistent with the gap value at the end position of the strong-ordinary spin.
The room temperature plastic deformation capability of the 2195 aluminum lithium alloy is poor, so that hot spinning is required, the hot spinning temperature is relatively high, the core die and the plate blank are expanded in the spinning deformation process, the actual gap between the spinning roller and the core die is lower than the theoretical gap, and the actual wall thickness of the box bottom spinning part is lower than the theoretical value. The thermal expansion difference factor is considered in the gap design, so that the actual wall thickness of the spinning piece can be prevented from being greatly deviated from the theoretical wall thickness to the maximum extent, and meanwhile, the die attaching effect of the spinning piece can be effectively improved by adopting negative deviation, so that the forming quality and the forming precision of the spinning piece at the bottom of the box are improved.
(II) designing the forming track of the spinning part at the bottom of the box
The box bottom is an ellipsoid profile, and correspondingly, the outer profile of the spinning core die and the inner profile of the spinning part at the box bottom are also ellipsoid profiles. Selecting n semi-cone angle positions (n is less than or equal to 5), dividing a spinning core mould into (n +1) sections from a spinning starting position to a spinning finishing position, spinning the original spinning plate blank in sections, attaching the mould section by section, and finally forming the spinning part for the box bottom 2195 aluminum lithium alloy box bottom.
In the step (II), the spinning core mold region corresponding to the nth half cone angle position from the starting position is formed by adopting a strong-normal spinning combined method; and forming the spinning core mold region corresponding to the nth half cone angle position to the spinning finishing position by adopting a common spinning section.
In the step (II), the arc of the outer profile of the spinning core mould corresponding to the starting position to the 1 st half cone angle position is formedLong term called 2L1The corresponding segment is called segment 1; the arc length of the outer profile of the spinning core mold corresponding to the 1 st half cone angle position to the 2 nd half cone angle position is called 2L2The corresponding segment is called segment 2; by analogy, the arc length of the outer profile of the spinning core mold corresponding to the nth half cone angle position to the spinning end position is called 2Ln+1The corresponding segment is referred to as the (n +1) th segment. Mixing L with1、L2、……………Ln+1The thickness is controlled to be 300-520 mm.
In the step (II), the 1 st section to the (n +1) th section are divided into m (m is more than or equal to 2 and less than or equal to 4) equal parts. When the length value of the corresponding sectional arc is 300-410 mm, the value of m is 3; and when the length value of the corresponding sectional arc is 410-520 mm, the value of m is 4.
In the step (II), the elliptic arc of each segment is approximately regarded as a circular arc, and the central angle corresponding to the 1 st segment of the circular arc is called as omega1The central angle corresponding to the 2 nd arc is called omega2By analogy, the central angle corresponding to the (n +1) th segment of the circular arc is called as ωn+1。
In the step (II), after each subsection is equally divided into m sections, the mould sticking and forming of the subsection are realized through m passes, and all forming passes of the rotary pressing piece at the bottom of the box are shown as a formula (2):
in the formula: lambda is the number of all forming passes; m isiIs the number of equal parts of the ith segment; n is the selected number of half cone angle positions.
In the step (II), die attaching and forming are realized by m times aiming at the 1 st subsection, and the stroke of each time of forced rotation is L1And/m, starting the common rotation, wherein the stroke of the common rotation in each pass is L1The included angle between the ith pass common spin track and the spinning core die is (90-i omega)1M); aiming at the 2 nd subsection, die pasting and forming are realized through m times, and the stroke of each time of forced rotation is L2And/m, starting the common rotation, wherein the stroke of the common rotation in each pass is L2The included angle between the ith pass of the normal spinning track and the spinning core die is (90-omega)1-iω2(ii)/m; and by analogy, die attaching and forming are realized by m times aiming at the (n +1) th subsection, and the stroke of each time of strong rotation is Ln+1And/m, starting the common rotation, wherein the stroke of the common rotation in each pass is Ln+1The included angle between the ith pass of the normal spinning track and the spinning core die is (90-omega)1-ω2…-ωn-iωn+1/m)。
The method has the advantages that the 2195 aluminum lithium alloy box bottom spinning part is prepared by adopting the tracks of sectional spinning and die attaching section by section, the strong-normal spinning stroke can be accurately distributed and controlled, the wall thickness thinning effect caused by unreasonable strong-normal spinning stroke is avoided, and the method is favorable for ensuring the tire attaching degree and the wall thickness precision of the box bottom spinning part.
(III) preparing 2195 aluminum lithium alloy spinning plate blank
Preparing 2195 aluminum lithium alloy spinning plate blank according to the volume invariance principle, and setting the diameter of the spinning plate blank to be D0。
And (IV) clamping and fixing the 2195 aluminum lithium alloy spinning plate blank prepared in the step (III), and performing spinning deformation according to the gaps and the forming tracks designed in the step (I) and the step (II) until the 2195 aluminum lithium alloy spinning plate blank is formed into a box bottom spinning part.
In the step (IV), the full rotation process adopts a process of alternately performing forward rotation and backward rotation, namely the forward rotation process is adopted in the first pass, the backward rotation process is adopted in the second pass, the forward rotation process is adopted in the third pass, the backward rotation process is adopted in the fourth pass, and the like, the forming of the box bottom spinning part is realized through the multi-pass forward-backward rotation alternate process and the combination of strong rotation and normal rotation, the hidden troubles that the wall thickness is thinned due to the full forward rotation process and the defects that the full backward rotation is easy to bulge and extrude and the like are avoided, and the forming quality of the 2195 aluminum lithium alloy box bottom spinning part is improved.
And (V) demolding the 2195 aluminum lithium alloy box bottom spinning part formed in the step (IV), and sequentially carrying out T6 heat treatment and inner/outer surface machining on the box bottom spinning part to realize the preparation of the 2195 aluminum lithium alloy integral spinning box bottom with phi 3350 mm.
Compared with the prior art, the invention has the following beneficial effects:
(1) aiming at the difficult problem of wall thickness control of the phi 3350mm2195 aluminum lithium alloy integral box bottom spinning part, the thermal expansion difference compensation formula is combined with negative offset, a forming gap is accurately designed, and the wall thickness precision of the box bottom spinning part is favorably ensured; through the accurate design and control of the spinning pass and the strong-common spinning stroke, the spinning and pressing piece at the bottom of the box is subjected to segmented spinning and die attaching section by section, so that the forming quality of the spinning and pressing piece at the bottom of the box is favorably ensured; by adopting the forming process combining positive-reverse rotation alternate and strong-normal rotation, the drawing effect of the box bottom spinning part is avoided, and the high-quality forming of the phi 3350mm2195 aluminum lithium alloy integral box bottom spinning part is realized.
(2) The forming clearance is designed by considering the influence of the forming temperature, the actual wall thickness of the box bottom spinning part is prevented from being greatly deviated from a theoretical value, and a negative deviation coefficient is introduced, so that the wall thickness precision and the profile degree of the box bottom spinning part are improved.
(3) When the forming device is designed into a forming track, the whole molded surface is divided into a plurality of sections, and each section is equally divided, so that the box bottom spinning part is formed in sections and attached to the die section by section, the full-rotation strong rotation and the normal rotation stroke are accurately controllable, and the wall thickness precision of the box bottom spinning part is improved.
(4) According to the forming track designed by the invention, the included angle between the normal spin curve of each pass and the spinning core mold is accurate and controllable, the strong-normal spin matching between passes is ensured, and the wall thickness precision of the spinning and pressing piece at the bottom of the box is favorably improved.
(5) The full rotation process of the invention adopts the process of alternately performing forward rotation and backward rotation and combining strong rotation and normal rotation, reduces the wall thickness thinning effect of the spinning part at the bottom of the box, avoids spinning defects such as bulging, backward extrusion and the like, and is beneficial to improving the forming quality of the spinning part at the bottom of the box.
(6) The invention relates to a wall thickness control method of a phi 3350mm2195 aluminum lithium alloy integral box bottom spinning part, which realizes accurate design of forming gaps and tracks and accurate distribution and accurate control of full-rotation-strong-normal-rotation travel, and the obtained phi 3350mm2195 aluminum lithium alloy integral box bottom spinning part has better forming quality and forming accuracy, the thickness difference of the same annular wall is less than or equal to 0.8mm, and the difference between the measured wall thickness value and the theoretical wall thickness value is less than or equal to 0.5 mm.
Drawings
FIG. 1 is a schematic illustration of a gap setting position and segmentation;
FIG. 2 is a schematic view of the arc lengths of the segments;
FIG. 3 is a schematic diagram of the equal division of each segment m and the strong rotation stroke of each segment;
FIG. 4 is a schematic diagram of the central angle corresponding to each segmented arc;
FIG. 5a is a schematic view of a first segmented spin deformation;
FIG. 5b is a schematic view of the (n +1) th segmented spin-forming;
fig. 6 is a schematic view of a 2195 aluminum lithium alloy box bottom spinning part.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
A wall thickness control method for a 2195 Al-Li alloy integral box bottom spinning part with a diameter of phi 3350mm comprises the following steps:
(1) determine the forming clearance of the rotary pressing piece 3 at the bottom of the box
According to the external surface generatrix equation and the thermal expansion difference compensation formula of the spinning core mold 1, the forming clearance of the spinning and pressing member 3 at the bottom of the box is designed, and meanwhile, in order to improve the mold sticking effect of the spinning and pressing member 3 at the bottom of the box, the clearance is designed by adopting negative deviation, as shown in the formula (3):
ti＝[t0Sinαi+Xi(T-T0)(M-N)]K……………(3)
in the formula: t is tiIs a half cone angle alphaiDesigning a gap at the position; t is t0The thickness of the spinning plate blank 2; alpha is alphaiIs a half cone angle; xiIs a half cone angle alpha of a core moldiAbsolute value of abscissa of position; t is the spinning deformation temperature; t is0Is at room temperature; m is the linear expansion coefficient of 2195 Al-Li alloy at the spinning deformation temperature; n is the linear expansion coefficient of the material of the core mould 1 at the spinning deformation temperature; k is a negative offset coefficient and is 0.90-0.95.
The formula (3) is only suitable for the gap design in the strong-ordinary spin forming and die attaching stages, and the gap design value in the ordinary spin forming and die attaching stages is consistent with the gap value at the end position of the strong-ordinary spin.
Because 2195 aluminium-lithium alloy has poor room temperature plastic deformability, hot spinning must be adopted, and the hot spinning temperature is relatively high, which inevitably causes the core mould 1 and the slab 2 to expand in the spinning deformation process, so that the actual gap between the spinning roller and the core mould 1 is lower than the theoretical gap, and the actual wall thickness of the box bottom spinning part 3 is lower than the theoretical value. The thermal expansion difference factor is considered in the gap design, so that the actual wall thickness of the spinning part 3 can be furthest prevented from deviating from the theoretical wall thickness, and meanwhile, the die attaching effect of the spinning part 3 can be effectively improved by adopting negative deviation, and the forming quality and the forming precision of the spinning part 3 at the bottom of the box are improved.
(2) Determining the forming track of the rotary pressing piece 3 at the bottom of the box
The box bottom is an ellipsoid profile, and correspondingly, the outer profile of the spinning core die 1 and the inner profile of the box bottom spinning part 3 are also ellipsoid profiles. Selecting n semi-cone angle positions (n is less than or equal to 5), dividing the spinning core die 1 into (n +1) sections from the spinning starting position to the spinning finishing position, as shown in figure 1, spinning the original spinning slab 2 in sections, attaching the die section by section, and finally forming the spinning die 3 at the bottom of the box body 2195 aluminum lithium alloy box.
In the step (2), the region of the spinning core mold 1 corresponding to the nth half cone angle position from the starting position is formed by a strong-normal spinning combined method; and forming the region of the spinning core die 1 corresponding to the nth half cone angle position to the spinning finishing position by adopting a common spinning section.
In the step (2), the arc length of the outer surface of the spinning core die 1 corresponding to the position from the start-up position to the 1 st half cone angle position is called as 2L1The corresponding segment is called segment 1; the arc length of the outer surface of the spinning core mold 1 corresponding to the 1 st half cone angle position to the 2 nd half cone angle position is called 2L2The corresponding segment is called segment 2; by analogy, the arc length of the outer surface of the spinning core mold 1 corresponding to the nth half cone angle position to the spinning end position is called as 2Ln+1The corresponding segment is referred to as the (n +1) th segment. Mixing L with1、L2、……Ln+1The thickness is controlled to be 300-520 mm, as shown in figure 2.
In the step (2), the 1 st segment to the (n +1) th segment are divided into m (m is more than or equal to 2 and less than or equal to 4) segments, and the m is divided into equal parts as shown in figure 3. When the length value of the corresponding sectional arc is 300-410 mm, the value of m is 3; when the length value of the corresponding sectional arc is 410-520 mm, the length value does not contain 410mm, and the value of m is 4.
In the step (2), the elliptic arc of each segment is approximately regarded as a circular arc, and the central angle corresponding to the 1 st segment of the circular arc is called as omega1The central angle corresponding to the 2 nd arc is called omega2By analogy, the central angle corresponding to the (n +1) th segment of the circular arc is called as ωn+1As shown in fig. 4.
In the step (2), after each subsection is equally divided into m sections, the subsection is attached to a die and formed through m passes, and all forming passes of the rotary pressing piece 3 at the bottom of the box are shown as a formula (4):
in the formula: lambda is the number of all forming passes; m isiIs the number of equal parts of the ith segment; n is the selected number of half cone angle positions.
In the step (2), die attaching and forming are realized by m times aiming at the 1 st subsection, and the stroke of each time of forced rotation is L1And/m, starting the common rotation, wherein the stroke of the common rotation in each pass is L1The included angle between the ith pass common spin track and the spinning core die 1 is (90-i omega)1M); aiming at the 2 nd subsection, die pasting and forming are realized through m times, and the stroke of each time of forced rotation is L2And/m, starting the common rotation, wherein the stroke of the common rotation in each pass is L2The included angle between the ith pass common spin track and the spinning core die 1 is (90-omega)1-iω2(ii)/m; and by analogy, die attaching and forming are realized by m times aiming at the (n +1) th subsection, and the stroke of each time of strong rotation is Ln+1And/m, starting the common rotation, wherein the stroke of the common rotation in each pass is Ln+1The included angle between the ith pass common spin track and the spinning core die 1 is (90-omega)1-ω2…-ωn-iωn+1/m) as shown in fig. 3, 5a, 5 b.
The 2195 aluminum lithium alloy box bottom spinning and pressing piece 3 is prepared by adopting a track of sectional spinning and die attaching section by section, the strong-normal spinning stroke can be accurately distributed and accurately controlled, the wall thickness thinning effect caused by unreasonable strong-normal spinning stroke is avoided, and the box bottom spinning and pressing piece 3 is favorably ensured in tire attaching degree and wall thickness precision.
(3) Preparation of 2195 aluminium lithium alloy spinning slab 2
Preparing a 2195 aluminum lithium alloy spinning slab 2 according to a volume invariance principle, and setting the diameter of the spinning slab 2 to be D0。
(4) Clamping and fixing the 2195 aluminum lithium alloy spinning plate blank 2 prepared in the step (3), and carrying out spinning deformation according to the gaps and the forming tracks designed in the step (1) and the step (2) until the 2195 aluminum lithium alloy spinning plate blank 2 is formed into a box bottom spinning part 3, as shown in fig. 6.
In the step (4), the full rotation process adopts a process of alternately performing forward rotation and backward rotation, namely the forward rotation process is adopted in the first pass, the backward rotation process is adopted in the second pass, the forward rotation process is adopted in the third pass, the backward rotation process is adopted in the fourth pass, and the like, the forming of the bottom spinning piece 3 is realized through the multi-pass forward-backward rotation alternate process and the combination of strong and normal rotation, the wall thickness thinning effect caused by the full forward rotation process and the defects that the bulging, backward extrusion and the like are easily caused by the full backward rotation process are avoided, and the forming quality of the bottom spinning piece 3 of the 2195 aluminum-lithium alloy box is favorably improved.
(5) And (3) demolding the 2195 aluminum lithium alloy box bottom spinning and pressing piece 3 formed in the step (4), and sequentially carrying out T6 heat treatment and inner/outer surface machining on the box bottom spinning and pressing piece 3 to realize the preparation of the 2195 aluminum lithium alloy integral spinning box bottom with phi of 3350 mm.
Example (b):
in the embodiment, the internal profile generatrix equation of the spun-pressed part 3 at the bottom of the 2195 aluminum lithium alloy box is the same as the external profile generatrix equation of the spun-pressed core die 1, is elliptical and has no straight line segment; the major semi-axis of the elliptic surface is 1662mm, and the minor semi-axis is 1036.125 mm; the diameter phi of the small-end platform of the box bottom spinning and pressing piece 3 is 400mm, and the distance between the large-end port of the box bottom spinning and pressing piece 3 and the equator is 104mm, as shown in figure 6. The specific process of the wall thickness control method for the 2195 Al-Li alloy integral box bottom spinning part with phi of 3350mm comprises the following steps:
a wall thickness control method for 2195 Al-Li alloy integral box bottom spinning part with phi of 3350mm comprises the following steps:
step (1) designing a forming gap of a spinning and pressing piece 3 at the bottom of a box
According to the external surface generatrix equation and the thermal expansion difference compensation formula of the spinning core mold 1, the forming clearance of the spinning and pressing member 3 at the bottom of the box is designed, and meanwhile, in order to improve the mold sticking effect of the spinning and pressing member 3 at the bottom of the box, the clearance is designed by adopting negative deviation, as shown in a formula (5):
ti＝[t0Sinαi+Xi(T-T0)(M-N)]K……………(5)
in the formula: t is t0The thickness of the spinning plate blank 2 is 40 mm; alpha is alphaiFor half cone angles, 3 typical half cone angles are selected, namely 75 degrees, 60 degrees and 45 degrees respectively; xiIs a half cone angle alpha of a core mold 1iAbsolute values of abscissas of the positions, namely absolute values of the abscissas corresponding to the positions with half cone angles of 75 degrees, 60 degrees and 45 degrees are 656.5, 1129.7 and 1411.1 respectively; t is the spinning deformation temperature of 300-400 ℃; t is0At room temperature of 20 ℃; m is 2195 Al-Li alloy with linear expansion coefficient of 23 multiplied by 10 at the spinning deformation temperature of 300-400 DEG C-6(ii) a N is the linear expansion coefficient of 14 multiplied by 10 of the material of the core die 1 at the spinning deformation temperature of 300-400 DEG C-6(ii) a K is a negative offset coefficient and is 0.90-0.95; specifically, as shown in table 1:
TABLE 1
| Position of | Starting position A | B | C | D | End part E |
| Half cone angle alphai/° | 84.5 | 75 | 60 | 45 | / |
| Absolute value of abscissa Xi | 200 | 656.5 | 1129.7 | 1411.1 | / |
| T-T0/℃ | 280 | 280 | 330 | 350 | / |
| Negative coefficient of departure K | 0.95 | 0.93 | 0.93 | 0.91 | / |
| Design wall thickness ti/mm | 38.3 | 37.5 | 35.3 | 29.8 | 29.8 |
Step (2) designing a forming track of the rotary pressing piece 3 at the bottom of the box
The external profile of the spinning core die 1 and the internal profile of the spinning die 3 at the bottom of the box are ellipsoidal profiles. Selecting 3 half cone angle positions which are respectively 75 degrees, 60 degrees and 45 degrees, dividing the spinning core die 1 into 4 sections from the spinning starting position to the spinning finishing position, as shown in figure 1, spinning the original spinning plate blank 2 in sections, attaching the die section by section, and finally forming the spinning part 3 at the bottom of the box bottom 2195 aluminum lithium alloy box.
Forming in the area of the spinning core die 1 corresponding to the position from the start-spinning position to the position with the half cone angle of 45 degrees by adopting a strong-normal spinning combined method; and forming the area of the spinning core die 1 corresponding to the position from the half cone angle of 45 degrees to the spinning finishing position by adopting a common spinning hand.
The arc length of the outer surface of the spinning core die 1 corresponding to the position from the spinning starting position to the position of 75 degrees of the half cone angle is called 2L1The corresponding segment is called segment 1, L1463.2; the arc length of the outer surface of the spinning core die 1 corresponding to the position from the half cone angle of 75 degrees to the position from the half cone angle of 60 degrees is called 2L2The corresponding segment is called segment 2, L2Is 512.5; the arc length of the outer surface of the spinning core die 1 corresponding to the position from the half cone angle of 60 degrees to the position from the half cone angle of 45 degrees is called 2L3The corresponding segment is called segment 3, L3353.5; the arc length of the outer profile of the spinning core mold 1 corresponding to the position from the half cone angle of 45 degrees to the spinning end position is called 2L4The corresponding segment is called segment 4, L4It was 503.4.
Dividing the 1 st segment to the 4 th segment into 4, 3 and 4 equal parts respectively; central angles corresponding to the 1 st segment to the 4 th segment are respectively 10.6 degrees, 14.9 degrees and 35.8 degrees; the total number of forming passes was 15.
Aiming at the 1 st subsection, die sticking and forming are realized through 4 times, the stroke of each time of forced spinning is 115.8mm, then the normal spinning is started, the stroke of each time of normal spinning is 115.8mm, and the included angle between the i-th time of normal spinning track and the spinning core die 1 is (90-2.65 i); aiming at the 2 nd subsection, die sticking and forming are realized through 4 times, the stroke of each time of forced spinning is 128.1mm, then the normal spinning is started, the stroke of each time of normal spinning is 128.1mm, and the included angle between the i-th time of normal spinning track and the spinning core die 1 is (90-10.6-3.73 i); aiming at the 3 rd subsection, die sticking and forming are realized through 3 times, the stroke of each time of forced spinning is 117.8mm, then the normal spinning is started, the stroke of each time of normal spinning is 117.8mm, and the included angle between the i-th time of normal spinning track and the spinning core die 1 is (90-10.6-14.9-3.73 i); and aiming at the 4 th subsection, die sticking and forming are realized through 4 passes, the stroke of each pass of strong rotation is 125.9mm, then normal rotation is started, the stroke of each pass of normal rotation is 125.9mm, and the included angle between the track of the i-th pass of normal rotation and the spinning core die 1 is (90-10.6-14.9-14.9-8.95 i).
Step (3) preparing 2195 aluminum lithium alloy spinning plate blank 2
And preparing the 2195 aluminum lithium alloy spinning plate blank 2 according to a volume invariant principle, wherein the diameter of the spinning plate blank 2 is set to be phi 3900 +/-50 mm.
And (4) clamping and fixing the 2195 aluminum lithium alloy spinning plate blank 2 prepared in the step (3), and performing spinning deformation according to the gaps and the forming tracks designed in the step (1) and the step (2) until the 2195 aluminum lithium alloy spinning plate blank 2 is formed into a box bottom spinning part 3.
The full rotation process adopts a process of alternately performing forward rotation and backward rotation, namely, the forward rotation process is adopted in the first pass, the backward rotation process is adopted in the second pass, the forward rotation process is adopted in the third pass, the backward rotation process is adopted in the fourth pass, and the like, the forming of the box bottom spinning part 3 is realized through the multi-pass forward rotation and backward rotation alternate process and the combination of strong rotation and normal rotation, the hidden troubles of wall thickness thinning effect caused by the full forward rotation process and the defects of bulging, backward extrusion and the like easily caused by the full backward rotation are avoided, and the forming quality of the 2195 aluminum lithium alloy box bottom spinning part 3 is improved.
And (5) demolding the 2195 aluminum lithium alloy box bottom spinning and pressing piece 3 formed in the step (4), and sequentially carrying out T6 heat treatment and inner/outer surface machining on the box bottom spinning and pressing piece 3 to realize the preparation of the 2195 aluminum lithium alloy integral spinning box bottom with the diameter of 3350 mm.
In the embodiment, aiming at the difficult problem of wall thickness control of the phi 3350mm2195 aluminum lithium alloy integral box bottom spinning part, a thermal expansion difference compensation formula is combined with negative offset, a forming gap is accurately designed, and the wall thickness precision of the box bottom spinning part is improved; through the accurate design and control of the spinning pass and the strong-common spinning stroke, the spinning and pressing piece at the bottom of the box is subjected to segmented spinning and die attaching section by section, so that the forming quality of the spinning and pressing piece at the bottom of the box is improved; by adopting the forming process combining positive-reverse rotation alternate and strong-normal rotation, the drawing effect of the box bottom spinning part is avoided, and the high-quality forming of the phi 3350mm2195 aluminum lithium alloy integral box bottom spinning part is realized. The thickness difference of the same annular wall of the obtained 2195 aluminum lithium alloy integral box bottom spinning part with the phi 3350mm is less than or equal to 0.8mm, and the difference between the actually measured wall thickness value and the theoretical wall thickness value is less than or equal to 0.5 mm.
Those skilled in the art will appreciate that those matters not described in detail in the present specification are well known in the art.
Although the present invention has been described with reference to the preferred embodiments, it is not intended to limit the present invention, and those skilled in the art can make variations and modifications of the present invention without departing from the spirit and scope of the present invention by using the methods and technical contents disclosed above.
Claims (9)
1. A method for controlling the wall thickness of a 2mm 2195 aluminum lithium alloy integral box bottom spinning part is characterized by comprising the following steps:
s1, determining a forming gap of a box bottom spinning part;
s2, determining the forming track of the box bottom spinning part;
s3, preparing an aluminum lithium alloy spinning plate blank;
s4, clamping and fixing the aluminum lithium alloy spinning plate blank prepared in the S3, and carrying out spinning deformation on the aluminum lithium alloy spinning plate blank according to the forming gap determined in the S1 and the forming track determined in the S2 to obtain a box bottom spinning part;
s5, demolding the box bottom spinning part, and then sequentially carrying out T6 heat treatment and inner/outer surface machining on the box bottom spinning part to finish the preparation of the box bottom.
2. The control method according to claim 1, wherein the forming track of the box bottom spinning part is segmented spinning and die attaching segment by segment; the method specifically comprises the following steps: selecting n semi-cone angle positions (n is less than or equal to 5), dividing the spinning core mould into (n +1) sections from the spinning starting position to the spinning finishing position, and forming the spinning core mould from the spinning starting position to the spinning core mould corresponding to the nth semi-cone angle position by adopting a strong-common spinning combined method; and forming the spinning core mold region corresponding to the nth half cone angle position to the spinning finishing position by adopting a common spinning section.
3. The control method according to claim 2, characterized in that the gap of the rotary pressing piece at the bottom of the box at the strong-normal rotary sticking and forming stage adopts the following method:
ti＝[t0Sinαi+Xi(T-T0)(M-N)]K
in the formula, tiIs a half cone angle alphaiDesigning a gap at the position; t is t0The thickness of the spinning plate blank; alpha is alphaiIs a half cone angle; xiIs a half cone angle alpha of a core moldiAbsolute value of abscissa of position; t is the spinning deformation temperature; t is0Is at room temperature; m is the linear expansion coefficient of 2195 Al-Li alloy at the spinning deformation temperature; n is the linear expansion coefficient of the core mould material at the spinning deformation temperature; k is a negative offset coefficient and has a value range of 0.90-0.95.
4. The control method as claimed in claim 2, wherein the gap of the bottom spinning member in the normal spin coating and forming stage is consistent with the gap of the strong-normal spin finishing position.
5. The control method according to claim 2, wherein the arc length of the outer surface of the spinning core mold corresponding to the 1 st half cone angle position from the start position is set to 2L1The corresponding segment is called segment 1; setting the arc length of the outer profile of the spinning core die corresponding to the 1 st half cone angle position to the 2 nd half cone angle position as 2L2The corresponding segment is called segment 2; by analogy, the arc length of the outer profile of the spinning core mould corresponding to the nth half cone angle position to the spinning end position is set as 2Ln+1The corresponding segment is referred to as the (n +1) th segment. Mixing L with1、L2、……Ln+1The length of (A) is controlled to be 300-520 mm.
6. The control method according to claim 2, characterized in that the 1 st to (n +1) th stages are each divided by m (2. ltoreq. m.ltoreq.4) equally; when the length value of the corresponding sectional arc is 300-410 mm, the value of m is 3; and when the corresponding sectional arc length value is 410-520 mm and does not contain 410mm, the value of m is 4.
After each subsection is equally divided into m sections, the mould sticking and forming of the subsection are realized through m passes, and all forming passes of the rotary pressing piece at the bottom of the box are as follows:
in the formula: lambda is the number of all forming passes; m isiIs the number of equal parts of the ith segment; n is the selected number of half cone angle positions.
7. The control method according to claim 2, wherein the elliptical arc of each segment is approximately regarded as a circular arc, and the central angle corresponding to the 1 st segment of the circular arc is called ω1The central angle corresponding to the 2 nd arc is called omega2By analogy, the central angle corresponding to the (n +1) th segment of the circular arc is called as ωn+1；
Aiming at the 1 st subsection, die pasting and forming are realized through m times, and the stroke of each time of forced rotation is L1And/m, starting the common rotation, wherein the stroke of the common rotation in each pass is L1The included angle between the ith pass common spin track and the spinning core die is (90-i omega)1M); for the 2 nd subsection, die pasting and forming are realized through m times, and each timeThe stroke of the secondary strong rotation is L2And/m, starting the common rotation, wherein the stroke of the common rotation in each pass is L2The included angle between the ith pass of the normal spinning track and the spinning core die is (90-omega)1-iω2(ii)/m; and by analogy, die attaching and forming are realized by m times aiming at the (n +1) th subsection, and the stroke of each time of strong rotation is Ln+1And/m, starting the common rotation, wherein the stroke of the common rotation in each pass is Ln+1The included angle between the ith pass of the normal spinning track and the spinning core die is (90-omega)1-ω2…-ωn-iωn+1/m)。
8. The control method according to claim 1, wherein in the process of spinning and deforming the aluminum-lithium alloy spinning plate blank to obtain the spinning and pressing piece at the bottom of the box, a forward-backward spinning alternative process is adopted, namely a forward spinning process is adopted in the first pass, a backward spinning process is adopted in the second pass, a forward spinning process is adopted in the third pass, a backward spinning process is adopted in the fourth pass, and the like; the forming of the box bottom spinning part is realized by a multi-pass forward-backward spinning alternative process and the combination of strong-normal spinning.
9. A phi 3350mm2195 aluminium-lithium alloy integral box bottom spinning part, characterized in that the wall thickness of the box bottom spinning part is controlled by the control method of any one of claims 1 to 8.
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