CN113601111A - Method for processing multi-slot bushing - Google Patents
Method for processing multi-slot bushing Download PDFInfo
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- CN113601111A CN113601111A CN202110824573.6A CN202110824573A CN113601111A CN 113601111 A CN113601111 A CN 113601111A CN 202110824573 A CN202110824573 A CN 202110824573A CN 113601111 A CN113601111 A CN 113601111A
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- 238000000034 method Methods 0.000 title claims abstract description 48
- 238000012545 processing Methods 0.000 title claims abstract description 11
- 238000010438 heat treatment Methods 0.000 claims abstract description 37
- 239000000463 material Substances 0.000 claims abstract description 30
- 238000003754 machining Methods 0.000 claims abstract description 10
- 238000013461 design Methods 0.000 claims abstract description 4
- 238000005553 drilling Methods 0.000 claims abstract description 4
- 238000001125 extrusion Methods 0.000 claims description 81
- 238000001816 cooling Methods 0.000 claims description 13
- 238000003672 processing method Methods 0.000 claims description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 5
- 238000004519 manufacturing process Methods 0.000 abstract description 11
- 238000005728 strengthening Methods 0.000 description 47
- 229910000808 amorphous metal alloy Inorganic materials 0.000 description 10
- 239000007769 metal material Substances 0.000 description 10
- 230000000694 effects Effects 0.000 description 6
- 239000007787 solid Substances 0.000 description 6
- 230000001788 irregular Effects 0.000 description 5
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 4
- 238000005520 cutting process Methods 0.000 description 4
- 230000005489 elastic deformation Effects 0.000 description 4
- 229910052751 metal Inorganic materials 0.000 description 4
- 239000002184 metal Substances 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- 238000004080 punching Methods 0.000 description 4
- 230000002787 reinforcement Effects 0.000 description 4
- 239000010935 stainless steel Substances 0.000 description 4
- 229910001220 stainless steel Inorganic materials 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 3
- 230000003014 reinforcing effect Effects 0.000 description 3
- 238000013000 roll bending Methods 0.000 description 3
- 238000007493 shaping process Methods 0.000 description 3
- 238000004088 simulation Methods 0.000 description 3
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical group [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- 229910001069 Ti alloy Inorganic materials 0.000 description 2
- 238000000641 cold extrusion Methods 0.000 description 2
- 238000005260 corrosion Methods 0.000 description 2
- 230000007797 corrosion Effects 0.000 description 2
- 239000000314 lubricant Substances 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- CWQXQMHSOZUFJS-UHFFFAOYSA-N molybdenum disulfide Chemical compound S=[Mo]=S CWQXQMHSOZUFJS-UHFFFAOYSA-N 0.000 description 2
- 229910052982 molybdenum disulfide Inorganic materials 0.000 description 2
- 229910052759 nickel Inorganic materials 0.000 description 2
- 239000011148 porous material Substances 0.000 description 2
- 238000004881 precipitation hardening Methods 0.000 description 2
- 238000005096 rolling process Methods 0.000 description 2
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 101100333320 Neurospora crassa (strain ATCC 24698 / 74-OR23-1A / CBS 708.71 / DSM 1257 / FGSC 987) end-3 gene Proteins 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 description 1
- 238000005299 abrasion Methods 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 238000000137 annealing Methods 0.000 description 1
- 229910001566 austenite Inorganic materials 0.000 description 1
- 238000013475 authorization Methods 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 239000011651 chromium Substances 0.000 description 1
- 239000010941 cobalt Substances 0.000 description 1
- 229910017052 cobalt Inorganic materials 0.000 description 1
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 1
- 238000010622 cold drawing Methods 0.000 description 1
- 238000005097 cold rolling Methods 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 230000003111 delayed effect Effects 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 229910000734 martensite Inorganic materials 0.000 description 1
- 238000005554 pickling Methods 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 229910052761 rare earth metal Inorganic materials 0.000 description 1
- 150000002910 rare earth metals Chemical class 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
- 239000010936 titanium Substances 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
- 238000013519 translation Methods 0.000 description 1
- 229910052726 zirconium Inorganic materials 0.000 description 1
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23P—METAL-WORKING NOT OTHERWISE PROVIDED FOR; COMBINED OPERATIONS; UNIVERSAL MACHINE TOOLS
- B23P15/00—Making specific metal objects by operations not covered by a single other subclass or a group in this subclass
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Abstract
The invention provides a method for processing a multi-slot bushing, which comprises the following steps: (1) the material selected for preparing the multi-split bushing is 0Cr17Ni7 Al; (2) blanking 0Cr17Ni7Al bar stock based on the structural parameters of the extruded workpiece; (3) performing rough machining on the 0Cr17Ni7Al bar stock after blanking according to the design size of the multi-slot bushing; (4) performing heat treatment on the rough-machined bar stock by using a TH565 heat treatment system; (5) drilling and forming the heat-treated 0Cr17Ni7Al bar stock into a bushing; (6) the bushing slots form a multi-split bushing. The invention has high production efficiency and high processing precision, can improve the surface quality of the hole wall of the assembly hole of the extruded workpiece and improve the fatigue performance of the extruded workpiece.
Description
Technical Field
The invention discloses a method for processing a multi-slit bushing, belongs to the technical field of hole extrusion strengthening precision machining, and particularly relates to a method for processing a multi-slit bushing capable of improving extrusion strengthening of a typical structural member assembly hole of a large-scale wide-body passenger plane.
Background
The method for carrying out extrusion strengthening on the assembling hole of the extruded workpiece by using the slotted bush is a more advanced hole extrusion strengthening technology in the current aircraft manufacturing industry, and the technology can enable the hole wall of the assembling hole of the extruded workpiece to form a uniform residual stress field, so that the fatigue strength of the extruded workpiece can be improved, the fatigue gain is increased, and the fatigue life of the extruded workpiece is prolonged.
The slotted bush used in the hole extrusion strengthening technology is generally manufactured by a roll bending forming method, and the bush manufacturing method aims at the bush with a single slot and thin bush thickness. For example, the authorized publication number is: CN109108589B, a chinese patent document, provides a method for processing a slotted bushing, comprising the following steps: the method comprises the steps of carrying out heat treatment on a stainless steel plate which is not subjected to heat treatment before leaving a factory, adjusting the thickness by rolling and leveling on a roller press according to needs, calculating and arranging samples and cutting the samples into strip-shaped raw materials to be processed. The authorization publication number is: CN107881309B, the patent document provides a slotted bushing for hole extrusion strengthening and a strengthening method, the slotted bushing of the invention is made of amorphous alloy strip, and the amorphous alloy is iron-based amorphous alloy, zirconium-based amorphous alloy, nickel-based amorphous alloy, titanium-based amorphous alloy, cobalt-based amorphous alloy, rare earth-based amorphous alloy or copper-based amorphous alloy. The strengthening steps are as follows: determining an amorphous alloy strip for manufacturing the slotted liner; preparing a blank of the slotted bushing; installing a slotted bushing; and (4) extruding and strengthening. The provided slotted bush for extruding and strengthening the hole and the strengthening method simplify the manufacturing process, save the manufacturing tool, shorten the manufacturing period and reduce the manufacturing cost; for holes with ultra-large or ultra-small diameters, the processing difficulty of the slotted liner is reduced, and material hardening and cracking in the forming process are avoided. Application publication No. CN101530873 proposes a manufacturing process of a split bush, which includes the following steps: selecting 1Cr17Ni7 hard stainless steel as a material, carrying out acid pickling with the wall thickness of 0.1-0.3 mm, spraying a molybdenum disulfide dry film lubricant on a single surface, blanking, chamfering, deburring, punching to be concave, namely punching to be V-shaped, then rolling to be a circle A, sleeving the circle A on a tightened and rolled core rod, putting into a die, punching to obtain a circle B, sleeving the circle B on a shaping core rod, arranging the shaping core rod with the taper of 1-3 degrees, putting into the die, punching, shaping to obtain a circle C, arranging the taper of the circle C to be 1-3 degrees, and finally curling; the molybdenum disulfide dry film lubricant can be sprayed on the inner wall of the slotted bushing after edge curling; the method solves the problem that thin-wall hard materials are difficult to form, has stable size and realizes stable production.
However, for hard materials with multiple slots and large bushing thickness, the multi-slot bushing is difficult to manufacture by a roll bending forming method; the traditional single slot is opened, the wall thickness of the bushing is thin, the bushing is easy to deform due to the thin wall thickness after the hole extrusion strengthening, the bushing cannot be reused, and the cost of the hole extrusion strengthening process is seriously increased; after single-slit and thin-wall bushing holes are used for extrusion strengthening, the protruding ridge generated at the slit position of the bushing is high, the protruding ridge undercut phenomenon is easy to occur, the protruding ridge generated at the slit position of the bushing after the holes are extruded and strengthened is high, the reaming amount is large, the large reaming amount influences a residual stress field formed on the hole wall, and therefore the fatigue strength of an extruded workpiece cannot be obviously improved.
Disclosure of Invention
The purpose of the invention is as follows: aiming at hard materials with multiple slots and large bushing thickness, the multi-slot bushing is difficult to realize by using a roll bending forming method; the problems that a single-slotted-wall thin bushing hole is easy to deform in the extrusion strengthening process, the bushing cannot be reused, the height of a convex ridge generated at a slotted position after extrusion strengthening is large, the reaming amount is large, the influence on residual stress on the wall of the hole is large and the like are solved, so that the hole extrusion strengthening process cost is high, and the fatigue strength of an extruded workpiece is not remarkably improved. Therefore, the invention provides a method for processing a multi-slot bushing. The multi-split bushing processed by the method has high hardness and thick bushing wall, and the multi-split bushing is not easy to deform in the hole extrusion strengthening process, so that the multi-split bushing can be repeatedly used, and the cost of the hole extrusion strengthening process is reduced; the liner is provided with a plurality of straight slits, the height of a convex ridge generated at each slit position after the holes are extruded and reinforced is small, the reaming amount is small, the influence on the residual stress formed on the hole wall is small, a uniform residual stress field is formed on the hole wall, and the assembly performance requirement of a large-sized wide-body passenger plane can be met.
The technical scheme is as follows: in order to realize the purpose of the invention, the invention adopts the following technical scheme:
a multi-slot bushing processing method comprises the following steps:
(1) selecting a bar stock material for making a multi-split bushing
The multi-split liner material is selected to be 0Cr17Ni7 Al. 0Cr17Ni7Al is a semi-austenitic precipitation hardening stainless steel which retains the austenitic structure when solution treated to cool to room temperature and is therefore easy to shape and which, by appropriate treatment, eventually transforms to a martensitic structure to a high strength level. The material contains a large amount of chromium and nickel, and has the characteristics of high strength, high hardness, excellent fatigue performance, small deformation during heat treatment, good formability and corrosion resistance under an annealing condition and the like.
(2) Blanking of bar stock for preparing multi-slit bush based on structural parameters of extruded workpiece
(3) Roughly machining the blanked bar stock according to the design size of the multi-slit bush
(4) Heat treatment is carried out on the rough machined bar
The heat treatment adopts a TH565 heat treatment system, and the treatment process comprises the following steps: and (3) at 1050 ℃, cooling the mixture in water or air at 760 ℃ for 90 min/air to be less than or equal to 15 ℃ and at 565 ℃ for 90min, and cooling the mixture in air. The 0Cr17Ni7Al material has different hardness and elongation obtained by different heat treatment methods. After heat treatment is carried out by using a TH565 heat treatment system, the hardness HRC of the material is 38-43, and the elongation is 9%. The multi-split bushing after heat treatment has high hardness, and the multi-split bushing is not easy to generate plastic deformation in the hole extrusion strengthening process; the elongation of the material is large, and the deformation of the multi-slit bushing material is easy to control in the elastic deformation range, so that the multi-slit bushing can be reused.
(5) Drilling and forming the heat-treated bar into a lining
The multi-slotted bushing is matched with the solid extrusion core rod for use, and the hole extrusion strengthening of the multi-slotted bushing is realized. In the hole extrusion strengthening process, the solid extrusion core rod working ring extrudes the inner wall of the multi-slotted bushing, the multi-slotted bushing deforms and extrudes the wall of the assembling hole, and the hole extrusion strengthening of the multi-slotted bushing is realized.
Before the hole extrusion is strengthened, the multi-slit bushing is placed at the guide section of the solid extrusion core rod, the hoop is placed in the middle of the multi-slit bushing, and the diameter of the front end of the multi-slit bushing is changed by contracting the hoop.
The outer diameter of the multi-slit bushing is designed according to the diameter of a final hole of an assembly hole of an extruded workpiece, and the inner diameter of the multi-slit bushing is the same as the diameter of a working ring of the solid extrusion core rod.
(6) Multi-slit bush formed by bush cutting groove
And (4) cutting grooves on the formed bush to form a multi-slot bush, wherein the number of slots is even number of slots such as 4 slots, 6 slots, 8 slots and the like.
In the hole extrusion strengthening process, the solid extrusion core rod working ring extrudes the inner wall of the multi-slotted bushing, the inner wall of the multi-slotted bushing generates elastic deformation to extrude the hole wall of the assembling hole, metal material on the hole wall generates metal flow, the metal material flows to the slotted position of the bushing, and the hole wall forms a convex ridge. The number of the slots arranged on the multi-slot bushing is large, and the number of the convex ridges formed on the hole wall is large, so that the plastic deformation of the hole wall is large, and the residual stress field formed on the hole wall is large. And selecting the multi-slit bushings with corresponding slit number according to the actual extrusion condition and the initial hole diameter of the assembly hole of the extruded workpiece.
The thickness of the bushing affects the quality of the bushing and the reinforcing effect of the bushing hole extrusion. The material 0Cr17Ni7Al is treated by a TH565 heat treatment system, and the hardness HRC is 38-43. The multi-slit bush is formed after the bush is grooved, and the multi-slit bush is hard to generate plastic deformation at the slit position due to high hardness after heat treatment. Therefore, the processing method can process the multi-slot bushing with the bushing thickness larger than 0.3 mm. The processed bush has small thickness, and the slotting part is easy to generate plastic deformation in the slotting process of the bush, so that the precision of the multi-slotting bush is seriously influenced, and the extrusion strengthening effect of the bush hole is influenced.
The formed bush cutting groove forms a multi-slot bush, and the width of each slot arranged on the multi-slot bush is a range. The seam width is set to be small, and the multi-seam bushing cannot be installed in an assembly hole of an extruded workpiece; the width of the slot is set to be large, and the rigidity of the multi-slot bushing is influenced. The width range of the seam arranged on the multi-seam bushing is set according to parameters such as the final hole diameter, the initial hole diameter, the relative extrusion amount and the like of the assembly hole of the extruded workpiece.
Has the advantages that: the invention provides a method for processing a multi-slot bushing, which has the following advantages:
1. the multi-split bushing material is 0Cr17Ni7Al, is semi-austenite precipitation hardening stainless steel, and has the characteristics of high strength, high hardness, excellent fatigue performance, small deformation during heat treatment, good formability, corrosion resistance and the like.
2. The processing method can process the slotted bushing with large bushing thickness and various slotted numbers, and has wide applicability.
3. After the multi-slot bushing hole is extruded and reinforced, convex ridges are generated at the slot positions of the bushing, a plurality of slots are formed in the bushing, the height of the convex ridge generated at each slot position is small, the reaming amount is small, and the influence of a residual stress field on the hole wall is small.
4. The multi-split bushing has high hardness and high elongation after heat treatment, and is not easy to generate plastic deformation in the hole extrusion strengthening process, so that the multi-split bushing is repeatedly used.
Drawings
FIG. 1 is a schematic structural view of a four-split bush obtained in example 1 of the present invention;
FIG. 2 is a cross-sectional view of FIG. 1;
fig. 3 is a flow chart for determining multi-split liner split width using measurement. Wherein, (a) the projections of the outer diameter and the inner diameter of the bushing are concentric circles; (b) the central line of the concentric circle is translated left and right and up and down; (c) the concentric circles are divided into four parts on average; (d) the four parts are translated uniformly; (e) the circumscribed circle after the translation of the four parts; (f) and measuring the diameter of the circumscribed circle.
Wherein, the tail part is-1; middle part-2; front end-3; a stop hole-4; slotting-5; outer diameter-6; inner diameter-7.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and examples.
Example 1
A multi-slot bushing processing method comprises the following steps:
(1) selecting a multi-slit lining material of 0Cr17Ni7 Al;
(2) blanking 0Cr17Ni7Al bar stock based on the structural parameters of the extruded workpiece;
(3) performing rough machining on the 0Cr17Ni7Al bar stock after blanking according to the design size of the multi-slot bushing;
(4) performing heat treatment on the rough-machined bar stock by using a TH565 heat treatment system;
(5) drilling and forming the heat-treated 0Cr17Ni7Al bar stock into a bushing;
(6) the bushing slots form a multi-split bushing.
Fig. 1 is a schematic structural view of a four-split bush obtained in embodiment 1 of the present invention, where a tail portion 1 of the multi-split bush is connected to a hole extrusion strengthening jig, and before hole extrusion strengthening, a clamp is used to apply an external force to a middle portion 2 of the multi-split bush to close a split of a front end 3, and reduce the diameter of the front end 3, so that the outer diameter of the multi-split bush is smaller than the aperture of a mounting hole of an extruded workpiece, thereby placing the front end 3 of the multi-split bush in the mounting hole of the extruded workpiece.
FIG. 3 is a cross-sectional view of FIG. 2 with the inner diameter of the multi-split sleeve being a stepped bore, the extrusion mandrel work ring extruding the inner wall of the multi-split sleeve nose 3 as it moves to the multi-split sleeve nose 3; when the working ring of the extrusion core rod moves to the middle part 2 of the multi-slotted bush, the working ring of the extrusion core rod does not extrude the inner wall of the multi-slotted bush, the stroke of the working ring of the extrusion core rod is reduced, and the abrasion of the working ring of the extrusion core rod is delayed.
Example 2 examination of Heat treatment
The 0Cr17Ni7Al material has three typical heat treatment systems: TH565, RH510 and CH480, and the influence of different heat treatment modes on the material performance is examined as follows:
the TH565 heat treatment system is as follows: and (3) at 1050 ℃, cooling the mixture in water or air at 760 ℃ for 90 min/air to be less than or equal to 15 ℃ and at 565 ℃ for 90min, and cooling the mixture in air. After the heat treatment of the TH565 heat treatment system, the HRC of the material is 38-43, sigmab1370MPa, sigma0.21280MPa and 9 percent of elongation.
The RH510 heat treatment system is as follows: and at 1050 ℃, performing water or air cooling at 950 ℃ for 10-30 min, performing air cooling at 73 ℃ for 4-8 h, performing cooling treatment at 510 ℃ for 30-60 min, and performing air cooling. After the heat treatment of the RH510 heat treatment system, the HRC of the material is 44-48, sigmab1620MPa, sigma0.21510MPa and an elongation of 6%.
③ CH480 Heat treatment System: at 1050 ℃, water or air cooling, cold rolling or cold drawing (the deformation is about 60 percent), 480 ℃ for 60min, and air cooling. After heat treatment of the CH480 heat treatment system, the HRC of the material is 49, sigmab1820MPa, sigma0.21780MPa and elongation of 2%.
It can be seen that the mechanical properties of the 0Cr17Ni7Al material are greatly changed after heat treatment according to different heat treatment systems. In the process of extruding and strengthening the multi-slotted bushing hole, the deformation of the bushing material is controlled within an elastic deformation range, and the hardness and the elongation of the bushing material need to be considered. If the hardness of the bushing material is too high, cracks are easily generated, and the service life of the bushing is influenced. The material has large elongation and large elastic deformation range, the multi-slotted bushing is elastically deformed after being subjected to extrusion force, and the multi-slotted bushing returns to the original shape after the holes are extruded and reinforced, so that the multi-slotted bushing is repeatedly used. Based on this, TH565 was selected for the multi-split liner heat treatment schedule.
Example 3
The following formula exists in the process of hole extrusion strengthening:
D+2t＝D0+Ea＝D0(1+Er) Wherein, in the step (A),
d is the diameter of the working ring of the extrusion core rod;
D0the diameter of the initial hole of the extruded workpiece;
t is the thickness of the bushing;
Errelative extrusion amount;
the nominal pore diameter is 16/32in, 25.4mm for 1in, and 12.7mm for 16/32in, i.e. 12.7mm for the final pore diameter. The final hole diameter is 12.7mm, and the relative extrusion amount E isr5 percent of the initial hole diameter D of the extruded workpiece0For example, 12.12mm, the measurement was used to explore the slot width of the multi-slot liner.
Initial hole diameter D012.12mm, relative extrusion ErAt 5%, D +2t is 12.73 mm.
When the diameter D of the extrusion core rod working ring is 10mm, the thickness t of the lining is 1.365 mm;
when the diameter D of the extrusion core rod working ring is 10.5mm, the thickness t of the lining is 1.115 mm;
when the diameter D of the extrusion core rod working ring is 11mm, the thickness t of the bushing is 0.865 mm;
when the diameter D of the extrusion core rod working ring is 11.5mm, the thickness t of the lining is 0.615 mm;
when the diameter D of the extrusion core rod working ring is 12mm, the thickness t of the lining is 0.365 mm;
when the diameter of the working ring is larger than 12mm, the thickness of the lining is smaller than 0.365 mm.
In the process of hole extrusion strengthening, the wall thickness of the bushing is small, the bushing is easy to generate plastic deformation, and the bushing cannot be reused. The thickness of the bushing is large, the plastic deformation degree of the hole wall of the assembling hole is small, and the residual compressive stress field formed on the hole wall is small, so that the hole extrusion strengthening effect is influenced.
Because the inner diameter of the bushing is the same as the diameter of the solid extrusion core rod working ring, the outer diameter D +2t of the bushing is 12.73mm, and the outer diameter of the bushing is larger than the diameter D of the initial hole of the assembly hole of the extruded workpiece0And the bushing cannot be placed in an assembly hole of an extruded workpiece, so that the extrusion reinforcement of the structural part with the hole cannot be realized. Therefore, the sleeve is provided with the slots, the outer diameter of the multi-slot sleeve is contracted before the holes are extruded and strengthened, and the outer diameter of the multi-slot sleeve is reduced, so that the multi-slot sleeve is enabled to be moreThe outer diameter is smaller than the diameter of the assembly hole of the extruded workpiece, and the multi-split bush can be installed in the assembly hole. The multi-slotted bush is small in slotted width, and the outer diameter of the contracted bush cannot meet the assembly requirement. Thus, there is a range of slit widths provided on the multi-slit bush.
The outer diameter of the multi-slot bushing is 12.73mm, the inner diameter of the bushing is 11.5mm, the aperture of an assembly hole of an extruded workpiece is 12.12mm, and the slot width of the multi-slot bushing is obtained by using a measuring method by taking the slot number as 4 slots as an example. And projecting the outer diameter and the inner diameter of the multi-slotted bushing to obtain concentric circles with the outer diameter of 12.73mm and the inner diameter of 12.12 mm.
As shown in fig. 3, the central line of the concentric circle is used as a reference, the central line of the concentric circle is moved a certain distance up and down, left and right, the concentric circle is evenly divided into four parts, the four parts into which the concentric circle is evenly divided are moved, the distance between each part is 0, an irregular figure is formed, a circle is drawn to be circumscribed with the irregular figure by taking the center of the irregular figure as the center, the diameter of the circle circumscribed with the irregular figure is measured, when the diameter is smaller than 12.12mm, the diameter of the shrunk outer diameter of the multi-split bush is smaller than the initial hole diameter of the extruded workpiece, the multi-split bush can be placed in the assembling hole of the extruded workpiece, and the hole extrusion strengthening is completed. If the diameter of the circumscribed circle of the irregular figure is larger than 12.12mm, the diameter of the contracted outer diameter of the multi-slit bushing is larger than the diameter of the initial hole of the extruded workpiece, and the multi-slit bushing cannot be placed in the assembling hole of the extruded workpiece and cannot finish hole extrusion strengthening. When the moving distance of the central line of the concentric circle is 0-0.35 mm, the diameter of the contracted outer diameter of the multi-split bushing is larger than 12.12mm, and the contracted multi-split bushing cannot be placed in the assembly hole of the extruded workpiece. When the distance of the movement of the central line of the concentric circle is more than 0.4mm, namely the slotting width of the multi-slotting bush is more than 0.8mm, the diameter of the contracted outer diameter of the multi-slotting bush is less than 12.12mm, and the contracted multi-slotting bush can be placed in an assembly hole of an extruded workpiece, so that the hole extrusion strengthening of the multi-slotting bush is realized.
Example 4
The invention discloses a process for reinforcing an assembly hole by cold extrusion of a slotted bush, which is provided by Chinese patent document CN112662965A, wherein ABAQUS finite element simulation analysis software is used for simulating the assembly hole of a TC4 titanium alloy plate with the diameter of 60mm multiplied by 10mm and a central hole of 12.12mm, and a single slotted bush and a 4 slotted bush are used for simulating the cold extrusion reinforcing process of the hole with the extrusion amount of 5 percent.
Extracting a tangential residual stress field simulation result formed by an extrusion end, a middle layer and an extrusion end of the wall of the assembling hole of the TC4 titanium alloy structural member based on a single-slotted bushing and 4-slotted bushing hole extrusion strengthening simulation process to obtain the extrusion end of the wall of the assembling hole, wherein the maximum residual compressive stress formed by the wall of the hole after extrusion strengthening of the single-slotted bushing is 480MPa, and the depth of the residual compressive stress layer is 5.1 mm; the maximum residual compressive stress generated by the hole wall after the 4-slotted bushing is extruded and strengthened is 510MPa, the depth of the residual compressive stress layer is 5.8mm, and the residual compressive stress generated by the hole wall after the 4-slotted bushing is extruded and strengthened at the same position with the hole wall is larger than that of the single-slotted bushing. And assembling the hole extrusion end, wherein the depth of a residual compressive stress layer generated on the hole wall after the extrusion strengthening of the 4-slit bushing is 5.8mm, the depth of a residual compressive stress layer generated on the hole wall after the extrusion strengthening of the single-slit bushing is 4.6mm, and the residual compressive stress generated on the hole wall after the extrusion strengthening of the 4-slit bushing is larger than that of the single-slit bushing at the same position with the hole wall. The residual stress field formed by the hole wall after extrusion strengthening shows that the extrusion strengthening effect of the 4-slotted bushing is superior to that of a single-slotted bushing.
After the single-slotted bushing and the multi-slotted bushing are extruded and reinforced, convex ridges are generated on the hole wall of the assembling hole corresponding to the slotted bushing. The single-slit bushing is provided with a slit, and only one convex ridge is generated on the wall of the hole after extrusion strengthening; the multi-slit bushing is provided with a plurality of slits, and after extrusion strengthening, the hole wall generates a plurality of convex ridges. The holes extrude and reinforce the assembly holes of the structural parts made of the same material and with the same aperture, and the extrusion force is the same in the extrusion and reinforcement process. However, because of the existence of a plurality of slots, the extrusion force is averagely distributed to each slot, the extrusion force born by each slot is small, the plastic deformation of the bushing is small, and the metal flowing degree of the metal material of the hole wall is small. Metal flow occurs on the metal material of the hole wall, a part of the metal material flows to the seam of the bushing to form a convex ridge, and the multi-seam bushing can form a plurality of convex ridges due to a plurality of seams; a portion of the metal material flows radially along the bore wall, causing plastic deformation. The multi-slot bushing has the advantages that the convex ridge generated at the slot position is small, so that the reaming amount is small, and the residual compressive stress field formed on the hole wall is small. A single-slit bushing is provided with a slit, the extrusion force borne by the slit of the bushing is large, the plastic deformation generated at the slit is large, the single-slit bushing is easy to generate the plastic deformation at the slit, the precision of an assembly hole of an extruded workpiece and the extrusion strengthening effect are influenced, the single-slit bushing cannot be reused, and the hole extrusion strengthening process cost is increased. In the extrusion strengthening process of the single slotted bushing hole, the bushing is subjected to plastic deformation to extrude and assemble the hole wall of the hole, metal material on the hole wall generates metal flow after being subjected to extrusion force, and a part of metal material flows to the slotted position of the bushing to form a convex ridge; a portion of the metal material flows radially along the bore wall, causing plastic deformation. The single-slit bushing is only provided with one slit, the height of the convex ridge generated at the slit position is large, and the metal material at the root of the convex ridge is forced to be elongated, so that the root of the convex ridge is easy to generate fatigue cracks; the ridge height generated at the seam is large, which causes large reaming amount and large residual compressive stress field on the hole wall. Based on the quantity and height of the convex ridges generated by assembling the hole wall after the hole is extruded and reinforced, the extrusion and reinforcement effect of the hole of the multi-slotted bushing is superior to that of the single-slotted bushing.
In conclusion, the residual stress field, the number of the convex ridges and the height of the convex ridges formed on the hole wall after the hole is extruded and reinforced have the advantage that the extrusion and reinforcement effect of the multi-slotted liner hole is obviously better than that of the single-slotted liner.
Claims (7)
1. A processing method of a multi-slot bushing is characterized by comprising the following steps:
(1) selecting a bar material for preparing the multi-slit bush;
(2) blanking a bar stock for preparing the multi-slit bush based on the structural parameters of the extruded workpiece;
(3) roughly processing the blanked bar stock according to the design size of the multi-slit bush;
(4) heat treating the rough-machined bar
(5) Drilling the heat-treated bar stock to form a lining;
(6) the bushing slots form a multi-split bushing.
2. The method for machining a multi-split bushing according to claim 1, wherein: in the step (1), the material of the multi-slit bush is selected to be 0Cr17Ni7 Al.
3. The method for machining a multi-split bushing according to claim 1, wherein: in the steps (5) and (6), the thickness of the lining is more than 0.3 mm.
4. The method for machining a multi-split bushing according to claim 1, wherein: in the step (4), a TH565 heat treatment system is used for carrying out heat treatment on the multi-slotted bushing, wherein the TH565 heat treatment system is 1050 ℃, water or air cooling +760 ℃ for 90 min/air cooling is carried out until the temperature is less than or equal to 15 ℃ and +565 ℃ for 90min, and air cooling is carried out; the hardness HRC of the material after heat treatment is 38-43, and the elongation is 9%.
5. The method for machining a multi-split bushing according to claim 1, wherein: and (4) determining the width of each slot of the multi-slot bushing obtained in the step (6) according to the following formula:
D+2t＝D0+Ea＝D0(1+Er) Wherein, in the step (A),
d is the diameter of the working ring of the extrusion core rod;
D0the diameter of the initial hole of the extruded workpiece;
t is the thickness of the bushing;
Eris the relative squeeze amount.
6. The method for machining a multi-split bushing according to claim 1, wherein: in the step (6), the number of the slits is more than one even number.
7. The method for machining a multi-split bushing according to claim 1, wherein: in the step (6), the width between the slots is not less than n pi r/90 ≧ (c)1-c2) Z, wherein:
n is an included angle formed by the outer diameter and the inner diameter of the bush after being evenly divided and the central line;
r is the radius of the outer diameter of the bushing;
c1the circumference being the outside diameter of the bushing;
c2assembling the initial hole perimeter of the hole for the extruded workpiece;
z is the number of slots.
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