CN-121972529-A - Preparation method of circular reducing high-performance external gradient tissue aluminum magnesium alloy tube blank

CN121972529ACN 121972529 ACN121972529 ACN 121972529ACN-121972529-A

Abstract

The invention discloses a method for preparing a circular reducing high-performance aluminum-magnesium alloy tube blank with an outer gradient structure, which belongs to the technical field of metal plastic processing. The metal flows directionally under the guidance of the back pressure cavity, the large plastic strain accumulated on the outer side of the pipe wall realizes grain refinement, the strain quantity on the inner side is reduced, an outer gradient structure is formed, and the male die sliding plate vertically upwards resets to enable the pipe blank to go through the diameter expanding stage again. The scheme synchronously completes geometric forming and outer gradient tissue construction in single-pass machining, has high forming precision and strong gradient controllability, and the prepared pipe has the advantages of wear resistance of external fine crystals and good toughness of internal coarse crystals, is suitable for high-end fields such as aerospace and the like, has excellent die universality and maintainability, and greatly improves the production efficiency.

Inventors

XUE YONG
LI XINING
XU JIAN
ZHANG HUIFANG
WU ANG
ZHANG ZHIMIN

Assignees

中北大学

Dates

Publication Date: 20260505
Application Date: 20260401

Claims (5)

1. A preparation method of a circular reducing high-performance external gradient tissue aluminum magnesium alloy tube blank comprises the following steps: s1, die assembly and tube blank preparation, namely preparing an upper die assembly, a male die sliding plate, a supporting box body, a sliding assembly, a left fixed push rod, The right fixed push rod and the lower template, the upper die assembly is connected with the upper slide block of the press, the male die slide plate is fixedly connected with the upper die assembly, the male die slide plate is provided with a left support rod and a right support rod which extend downwards, the left support rod is provided with a left inner upper inclined plane and a left inner lower inclined plane, the right support rod is provided with a right inner upper inclined plane and a right inner lower inclined plane, the heights of the left inner upper inclined plane and the left inner lower inclined plane are lower than those of the right inner upper inclined plane and the right inner lower inclined plane, the supporting box body is used as a main body supporting frame and is fixed on the lower template, the lower template is connected with the press workbench, the top of the supporting box body is provided with a socket for the left support rod and the right support rod to be inserted downwards, and the sliding assembly comprises a left thrust slide block, The die comprises a right thrust sliding block, an upper die box, a lower die box, a die core, a left thrust ring and a right thrust ring, wherein the upper die box and the lower die box are buckled together, the radius of a left half die core is larger than that of a right half die core to form a shaft-shaped structure with a variable diameter in the middle, the die core is arranged in the upper die box and the lower die box, a thick-diameter cavity is formed in the left half section of the die core and a thin-diameter cavity is formed in the right half section of the die core after buckling, the thin-diameter cavity and the thick-diameter cavity are respectively arranged as semicircular grooves on the upper die box and the lower die box, and because the radius of the left half die core is larger than that of the right half die core, the radius of the thick-diameter cavity is larger than that of the thin-diameter cavity, a gap is formed between the die core and the thin-diameter cavity and the thick-diameter cavity for a pipe blank, The left thrust ring and the right thrust ring are sleeved on the mold core and are used for propping against the pipe blank when the pipe blank is pushed; the left thrust sliding block and the right thrust sliding block are respectively hooped on two sides of the upper die box body and the lower die box body, the middle part of the left thrust sliding block is provided with a left fixed push rod in a penetrating way, one end of the left fixed push rod is fixed on the inner wall of the supporting box body, the other end of the left fixed push rod stretches into the thick diameter cavity to prop against the left thrust ring, the middle part of the right thrust sliding block is provided with a right fixed push rod in a penetrating way, one end of the right fixed push rod is fixed on the inner wall of the supporting box body, the other end of the right fixed push rod stretches into the thin diameter cavity to prop against the right thrust ring, the left thrust sliding block is provided with a left outer upper inclined surface for being matched with a left inner lower inclined surface of the male die sliding plate and a left outer lower inclined surface for being matched with a left inner lower inclined surface of the male die sliding plate, and the right outer upper inclined surface for being matched with a right inner lower inclined surface of the male die sliding plate, the mould core is firstly placed in a semicircular groove of the lower die box body, the aluminium magnesium alloy tube blank is preheated, the preheated tube blank is sleeved on a right half section with a smaller radius of the mould core, and the left thrust ring is sleeved on the two ends of the tube blank respectively, The right thrust ring is used for buckling the upper female die box body on the lower female die box body to form a complete small-diameter cavity and a complete large-diameter cavity, then the left thrust sliding block and the right thrust sliding block are sequentially and respectively hooped on two sides of the buckled female die box body to complete the assembly of the sliding component, then the upper die component is fixedly connected with the male die sliding plate and then is arranged on the upper sliding block of the press machine through bolts, the position of the press machine is adjusted to lead the left supporting rod and the right supporting rod of the male die sliding plate to be aligned with the jack at the top of the supporting box body, one end of the left fixed pushing rod and one end of the right fixed pushing rod are respectively fixed at the corresponding positions of the inner wall of the supporting box body, the other end of the left fixed pushing rod penetrates into the holes of the left thrust sliding block and the right thrust sliding block to enable the left thrust ring to prop against the left fixed pushing rod, The right thrust ring is propped against the right fixed push rod; Starting a press machine, wherein the press machine drives an upper die assembly to drive a male die sliding plate to vertically move downwards, a left support rod of the male die sliding plate stretches into a supporting box body along a socket, a left inner lower inclined surface of the left support rod is firstly attached to a left outer upper inclined surface of a left thrust sliding block, vertical pressure is converted into horizontal right thrust, the left thrust sliding block is pushed to drive an upper die box body, a lower die box body and a die core to slide horizontally and rightwards, at the moment, a tube blank is kept fixed in position under the axial limit of a left fixed push rod, a right fixed push rod and a thrust ring, the die core is matched with a small-diameter cavity and a large-diameter cavity of the die box body, metal directionally flows towards the direction of the large-diameter cavity under the pressure, radial expansion deformation is realized on the tube blank, the outer diameter of the tube blank is gradually expanded along with the movement of the die box body, and the primary expansion is completed; S3, necking down and forming an outer gradient structure, namely continuously vertically downwards moving a male die slide plate, wherein the height of a left inner lower inclined surface is lower than that of a right inner lower inclined surface, a right supporting rod of the male die slide plate downwards moves along with the lower height and stretches into a supporting box body, the left inner lower inclined surface of the left supporting rod is far away from the left outer upper inclined surface of a left thrust slide block, the right inner lower inclined surface of the right supporting rod is attached to the right outer upper inclined surface of the right thrust slide block, the right thrust slide block is pushed to drive an upper concave die box body and a die core to horizontally slide leftwards, a tube blank enters a necking down deformation stage, the wall thickness of the tube blank is increased under the radial compression action, metal directionally flows towards a small-diameter cavity under the action of pressure, the metal outside the tube wall is directly contacted with the inner wall of the concave die box body, namely is extruded at a back pressure cavity, severe shearing and compression deformation are carried out, large plastic strain is accumulated to realize grain refinement, and the strain quantity of the metal inside the tube wall gradually decreases along with the increase of depth, and an outer gradient structure with the grain size gradually increased from the surface to the inside is finally formed; S4, circularly forming and demoulding, namely controlling the male die slide plate to vertically go upwards and return, attaching the left inner upper inclined surface of the left support rod with the left outer lower inclined surface of the left thrust slide block, converting the vertical pressure into horizontal rightward thrust, driving the upper and lower female die boxes and the die core to slide horizontally rightward again, and repeating the diameter expanding process as in the step S2, so that one stroke is finished, multiple horizontal reciprocating motions are realized, and multiple diameter expanding-necking cycles of the tube blank are realized.
2. The method for preparing the circular reducing high-performance external gradient tissue aluminum magnesium alloy pipe blank is characterized in that an ejection mechanism is arranged on a supporting box body, in the step S4, after the pipe blank is formed, the ejection mechanism integrated with the supporting box body is started, the sliding assembly is integrally ejected out of the supporting box body, an operator splits the upper die box body and the lower die box body, and takes out the formed aluminum magnesium alloy pipe material, so that the whole preparation process is completed.
3. The method for preparing the circular reducing high-performance external gradient tissue aluminum-magnesium alloy tube blank according to claim 1, wherein guide grooves are respectively formed in the positions, corresponding to the left thrust sliding block and the right thrust sliding block, of the outer walls of the upper die box body and the lower die box body, guide blocks are respectively arranged on the left thrust sliding block and the right thrust sliding block, the directions of the guide grooves are perpendicular to the moving paths of the upper die box body and the lower die box body, and the left thrust sliding block and the right thrust sliding block are matched with the guide blocks in a sliding mode through the matching of the guide grooves and are respectively clamped on two sides of the upper die box body and the lower die box body.
4. The preparation method of the circular variable-diameter high-performance external gradient tissue aluminum magnesium alloy tube blank is characterized in that one end of a left fixed push rod is fixed on the inner wall of a supporting box body through a fastener, multi-petal columnar strips extend out of the other end of the left fixed push rod along the axial direction, the multi-petal columnar strips are arranged at intervals in a ring shape, extend into a large-diameter cavity and directly act on a left thrust ring, and the right fixed push rod and the left fixed push rod are of the same structural design, but the radius of the right fixed push rod is smaller than that of the left fixed push rod.
5. The method for preparing the circular variable-diameter high-performance external gradient tissue aluminum-magnesium alloy tube blank according to claim 4, wherein two ends of the die core extend out of the upper die box body and the lower die box body, a left thrust sliding block and a right thrust sliding block are respectively provided with a central groove and a plurality of flap holes encircling the edges of the central grooves, the plurality of flap holes correspond to the shape and the number of columnar bars, the die core is embedded in the central groove through protruding parts at two ends, the columnar bars of the left fixed push rod and the right fixed push rod are embedded in the plurality of flap holes, in the step S1, the right thrust sliding block is sequentially hooped on two sides of the buckled die box body, the protruding parts at two ends of the die core are embedded in the central grooves of the two thrust sliding blocks, one ends of the left fixed push rod and the right fixed push rod are respectively fixed at the corresponding positions of the inner walls of the supporting box body, and the other ends penetrate into the plurality of flap holes of the left thrust sliding block and the right thrust sliding block, so that a left thrust ring is abutted against the left fixed push rod and a right thrust ring is abutted against the right fixed push rod.

Description

Preparation method of circular reducing high-performance external gradient tissue aluminum magnesium alloy tube blank Technical Field The invention belongs to the technical field of metal plastic processing, and particularly relates to a preparation method of a circular variable-diameter high-performance aluminum magnesium alloy tube blank with an outer gradient structure, which is suitable for one-step forming preparation of the aluminum magnesium alloy tube blank, can synchronously realize geometric forming of the tube blank and construction of an outer gradient fine grain structure, and is used for preparing the high-performance aluminum magnesium alloy tube blank with fine grains on the outer part and coarse grains on the inner part. Background The high-performance light aluminum-magnesium alloy tube blank has increasingly-growing application requirements in the fields of aerospace, transportation, high-end equipment manufacturing and the like due to the characteristics of light weight and high specific strength. In practical engineering application, the tube blank is often subjected to bending, torsion, abrasion and other composite loads, the outer part of the tube blank is required to have high wear resistance, high strength and high fatigue performance, and the inner part of the tube blank maintains good toughness, namely, an outer gradient structure of outer fine crystals and inner coarse crystals is required to be constructed. The traditional aluminum-magnesium alloy tube blank preparation process can only obtain uniform microstructure, and can not realize gradient distribution of the microstructure, and the traditional gradient structure tube blank preparation method is mainly dependent on subsequent heat treatment, surface modification or complex composite process, and has the problems of long process flow, high preparation cost, weak interface bonding strength, poor gradient structure controllability and the like. The gradient tissue tube blank prepared by rotary back extrusion can only realize an inner gradient structure of inner fine crystals and outer coarse crystals, which is contrary to the outer gradient performance requirement of actual engineering. At present, a method for integrating geometric forming and external gradient tissue preparation of a tube blank is lacking, synchronous construction of cyclic reducing and external gradient tissue of the tube blank cannot be realized in single plastic working, and high-efficiency and short-flow preparation requirements of high-performance external gradient tissue aluminum magnesium alloy tube blanks are difficult to meet. Therefore, the invention designs a preparation method of the circular reducing high-performance external gradient structure aluminum magnesium alloy tube blank, which realizes multiple 'diameter expansion-necking' circulation of the tube blank through one pressure stroke, builds the external gradient structure by utilizing severe plastic deformation of the necking stage, and solves the defects in the prior art. Disclosure of Invention The invention aims to solve the problems that the preparation process of an aluminum magnesium alloy tube blank in the prior art cannot synchronously realize geometric forming and outer gradient tissue construction, the preparation process is complicated and the gradient controllability is poor, and provides a preparation method of a cyclic reducing high-performance outer gradient tissue aluminum magnesium alloy tube blank. According to the method, a male die slide plate with a customized profile drives a sliding component to do horizontal reciprocating motion, so that a tube blank is subjected to repeated 'diameter expansion-necking' cyclic deformation, large plastic strain is accumulated on the outer side of a tube wall by utilizing radial compression and metal directional flow of necking stages, gradient distribution of grain sizes from the outside to the inside is realized, and finally, the high-performance aluminum-magnesium alloy tube blank with fine grains on the outside and coarse grains on the inside is prepared, and the die structure is high in integration degree, high in forming precision and strong in gradient tissue controllability. To achieve the above object, the solution of the present invention is: A preparation method of a circular reducing high-performance external gradient tissue aluminum magnesium alloy tube blank comprises the following steps: s1, die assembly and tube blank preparation, namely preparing an upper die assembly, a male die sliding plate, a supporting box body, a sliding assembly, a left fixed push rod, The right fixed push rod and the lower template, the upper die assembly is connected with the upper slide block of the press, the male die slide plate is fixedly connected with the upper die assembly, the male die slide plate is provided with a left support rod and a right support rod which extend downwards, the left support rod is provided with a left inner