WO2013044599A1

WO2013044599A1 - Method for achieving high-pressure shearing deformation in tube materials by wedge principle and apparatus therefor

Info

Publication number: WO2013044599A1
Application number: PCT/CN2012/070157
Authority: WO
Inventors: 王经涛; 李政; 王进; 安钰坤
Original assignee: 南京理工大学
Priority date: 2011-09-30
Filing date: 2012-01-10
Publication date: 2013-04-04
Also published as: CN102500632A; CN102500632B

Abstract

A method of achieving high-pressure shearing deformation in tube materials by the wedge principle and an apparatus therefor. The method involves: selecting a workpiece to be processed (3), and using constraining bodies to respectively constrain the inner wall and the outer wall of the workpiece (3); exerting an axial pressure on the constraining bodies, increasing the axial force by taking advantage of the force amplifying principle of the wedge, and converting to a positive pressure in a direction perpendicular to a contact surface with the workpiece (3), thereby obtaining a high hydrostatic pressure inside the workpiece (3); providing a torque to one of the constraining bodies such that the constraining body rotates around a central axis of the workpiece (3), while fixing the other constraining body; or providing a torque to the two constraining bodies at the same time in opposite directions, such that the two constraining bodies rotate relatively around the central axis of the workpiece (3); and under the action of a tangential frictional force between the constraining bodies and the inner and outer walls of the workpiece (3), materials inside of the workpiece (3) at different radial thicknesses rotate at different angular velocities, achieving shearing deformation of the workpiece (3). Using the completely new plastic processing method implemented by conventional pressure devices expands the function of the conventional pressure devices, the feasibility thereof is high, operation thereof has no specific requirements, and the required device is simple.

Description

Method and device for realizing high pressure shear of pipe by using tip principle

Technical field

The invention relates to the field of material processing engineering, in particular to a method and a device for realizing high-pressure shear plastic deformation of a tubular material by using a tipping principle, which are mainly applied to various metal and alloy materials, inorganic non-metal materials and polymer materials, etc. To achieve plastic deformation of these materials under high hydrostatic pressure conditions, thereby controlling and optimizing its microstructure and improving its performance.

Background technique

Severe plastic deformation The method of deformation (SPD) is a general term for a series of plastic processing techniques with large deformation. The SPD method refines the grain effect obviously, and can refine the internal structure of the material to sub-micron, nano-scale or even amorphous [R. Z. Valiev. Nature materials. 2004 (3): 511-516.; R. Z. Valiev, A. K. Mukherjee. Scripta mater. 2001 (44): 1747–1750.]. In recent years, the technology of preparing bulk nanostructured materials by SPD method has received widespread attention from experts and scholars in the field of materials science. At the same time, a large number of researches have promoted the continuous development of SPD technology in the preparation of bulk ultrafine crystals and nanocrystalline materials. R.Z., Ufa Aviation Technical University, Russia The research team led by Valiev believes that the preparation of ultrafine grained materials by SPD method should satisfy a number of conditions [R. Z. Valiev, R. K. Islamgaliev, I V. Alexandrov. Progress in Materials Science. 2000 (45): 103-189.], mainly includes: large plastic deformation, relatively low deformation temperature and high hydrostatic pressure inside the deformed material. Under the guidance of this principle, various SPD processes and methods have been proposed and developed.

The most popular SPD method at present is mainly cumulative rolling (accumulative Roll-bonding (abbreviated ARB) technology, equal-channel angular pressing (ECAP) technology, and high-pressure torsion (high-pressure torsion, referred to as HPT) Technology, etc. The ARB technology is shown in Figure 1. It can continuously prepare thin-plate ultrafine-grained structural materials, and is easy to implement on traditional rolling mills. The equipment is simple and practical. However, in the ARB process, in order to achieve good rolling compounding, lubricants are often not used, which is detrimental to the service life of the rolls. At the same time, the hydrostatic pressure that can be achieved due to the deformation of the material during the rolling process is not high enough, and cracking will occur after a certain amount of deformation is accumulated during the processing. [N. Tsuji, Y. Saito, S. H. Lee, et al. Advanced Engineering Materials. 2003 (5) :338-344.]. The ECAP technology is shown in Figure 2. The use of this technology for ultra-fine grain metal processing has great potential. However, for some difficult-to-machine alloys (such as magnesium alloys), ECAP often cracks. If the deformation temperature is increased, the life of the mold will be affected on the one hand, and the grain refining effect will be affected on the other hand. In addition, due to the limitation of the mold material, the deformation temperature cannot be increased without limitation. Moreover, in order to achieve large cumulative plastic deformation, ECAP requires multiple passes and the operation is complicated. Back pressure ECAP (back pressure equal-channel angular pressing, BP-ECAP for short) That is, the ECAP technology of applying back pressure in the exit channel of the mold, as shown in FIG. 3, can solve the cracking problem of the difficult-to-deform metal ECAP to a certain extent, thereby improving the microstructure and mechanical properties of the material; the applied back pressure is limited, and the still water is The pressure is generally maintained at several hundred megapascals [R. YE. Lapovok. Journal of materials science. 2005 (40) :341-346.]. If the applied back pressure is too high, ECAP cannot be achieved due to factors such as friction and mold strength. The HPT technology shown in Figure 4 is the most suitable condition for the preparation of ultrafine grained materials in accordance with the SPD method mentioned in the previous section. Among the existing SPD technologies, HPT technology has the strongest grain refinement capability. However, the thickness of the specimen that HPT can process is small [A. P. Zhilyaev, T. G. Langdon. Progress in Materials Science. 2008 (53) : 893-979.], the processed disc-shaped sample has a large strain gradient in the radial direction, the deformation is uneven, and the degree of grain refinement is not uniform.

Tóth et al [L.S. Tóth, M. Arzaghi, J.J. Fundenberger, B. Beausir: Scr. Mater. Vol. 60 (2009), p. 175] proposes a high-pressure tube method for tubular materials (high-pressure tube) Twisting, HPTT), as shown in Figure 5, the elastic core rod is placed inside the tubular workpiece, and the rigid disc is placed on the outer side (rigid Disk), both ends of the sample are fixed with a baffle. When the mandrel is pressurized, the radial expansion of the mandrel creates radial pressure on the inner wall of the tubular workpiece, while the rigid disk creates a radial pressure in the opposite direction to the outer wall of the tubular workpiece, thereby creating hydrostatic pressure in the tubular workpiece. At this time, the ring sleeve is rotated, and the tubular workpiece is sheared under the surface friction. This method is very good. The main problem is that the method of loading the sample is radial loading. That is to say, the method directly applies axial pressure to the mandrel, and the mandrel produces a diameter on the sample. To the pressure. In this loading mode, the pressure is not directly loaded in the axial direction of the tubular material, and the hydrostatic pressure of the specimen is derived from the elastic deformation of the mandrel after being pressed. Since the elastic deformation of the mandrel is unlikely to be large, it is difficult to produce high The hydrostatic pressure, therefore, provides limited friction and is only suitable for pure metals with lower strength. For materials with higher strength, the frictional force that can be generated does not reach the yield strength of the material, and slipping and the like are likely to occur, and the required deformation cannot be achieved.

Another problem with the method is that the baffle at the two ends of the tubular workpiece is a cantilever beam structure, and the constraint on the axial deformation of the sample is insufficient. When the hydrostatic pressure of the sample is high, the material is easily extruded from the gap, affecting Processing process.

The invention proposes a technology for realizing high-pressure shear deformation of a tubular material by using the tip principle, and the principle of the wedge applied by the technology is also called the wedge effect or the principle of the beveling force. This principle can be used with the Lamy's theorem (Lami's Theorem) to explain: in the same plane, when the resultant force of the three co-point forces is zero, the ratio of any one of the forces to the sine of the other two forces is equal [R.K. Bansal (2005). Laxmi Publications. p. 4.]. The small angled bevel of the tip or wedge can be seen as a force amplifying device. As shown in Figure 5, when a force is applied to the opposite end of the tip, the object in contact with the bevel forming the tip will be much larger than the applied force. Positive pressure [Sybil P. Parker, ed., McGraw-Hill, Inc., 1992, p. 2041.]. This design produces a higher hydrostatic pressure in the sample more effectively than the high pressure torsion method of the tubular material proposed by Tóth et al.

technical problem

It is an object of the present invention to provide a new severe plastic deformation method and apparatus therefor: a technique for achieving high pressure shear of a pipe using a tip end principle. The high hydrostatic pressure of the invention utilizes the force amplification effect of the tip principle, so that the technology satisfies many conditions that should be satisfied by the SPD method for preparing the ultrafine grain material, such as large plastic deformation amount and relatively low deformation temperature. And the high hydrostatic pressure inside the deformed material. The method avoids the complicated process of multi-channel operation such as ARB, ECAP and back pressure ECAP. At the same time, due to the different nature of the loading method, the method also overcomes the problems of insufficient hydrostatic pressure of Tóth et al. When processing materials, it can provide high hydrostatic pressure conditions similar to HPT technology, which is suitable for the processing of difficult-to-deform metals and alloys, to achieve the effect of controlling and optimizing the structure of the material and improving its performance.

Technical solution

The technical solution for achieving the object of the present invention is: a method for realizing high-pressure shearing of a pipe by using a tipping principle, first selecting a machined workpiece, the workpiece is a tapered pipe, and the inner wall and the outer wall of the workpiece are respectively restrained by the restraining body; Applying axial pressure to one end of the restraining body, using the pressure-increasing and force-increasing characteristics of the tipping principle (also called the wedge effect or the principle of the beveling force), a high pressure is generated in a direction perpendicular to the inner and outer walls of the workpiece, so that the workpiece is elastically deformed. Or slight plastic deformation, the deformation of the workpiece is hindered by the reverse frictional force with the deformation trend, thereby generating a high hydrostatic pressure in the workpiece; then providing a torque to a restraining body in contact with the inner and outer walls of the workpiece to surround the center of the workpiece The shaft rotates while fixing the other restraint body; or the opposite direction torque is provided to the two restraint bodies at the same time. Under the action of the frictional force between the restraining body and the inner and outer walls of the workpiece, the materials at different thicknesses in the radial direction of the workpiece have different angular velocities. Rotate to achieve shear deformation of the workpiece.

A device for realizing high-pressure shearing of a pipe by using a tipping principle, comprising a press having a constant pressure function, a torque reducer providing torque, and a mold having a transfer pressure, a constraining deformation, and a partial rotation function; the mold includes: fixed or a rotatable rigid mandrel and a rotatable or fixed rigid collar; the workpiece is coaxially placed in the rigid collar, the inner surface of the rigid collar is in contact with the outer wall of the workpiece, and the interior of the workpiece is coaxially provided with a rigid mandrel, rigid core The outer surface of the shaft is in contact with the inner wall of the workpiece, and the rigid mandrel and the rigid ring sleeve are respectively mounted along the central axis or placed on the upper and lower bottom plates of the press, and the displacement of the rigid ring sleeve and the rigid mandrel is limited, only along Move axially or around the central axis.

Beneficial effect

Compared with the prior art, the invention has significant advantages: (1) the processing procedure is simple. The method for realizing high-pressure shearing of pipe by using the tip principle of the invention is a severe plastic deformation method which can be realized in a single pass on a conventional pressure device having a constant pressure function. In contrast, such as cumulative rolling (ARB) method, multi-directional forging, equal-angle extrusion (ECAP) method and back pressure ECAP method, etc., often require a lot of repeated process passes to achieve high strain plastic deformation, labor consumption . The method utilizes the friction between the rigid ring sleeve, the tubular workpiece and the mandrel and the tubular workpiece, so that the rigid ring sleeve and the rigid mandrel rotate relative to each other, and the outer layer region of the tubular workpiece contacting the rigid ring sleeve is opposite to the mandrel. Shearing between the inner regions of the contact, thereby achieving severe plastic deformation under a single process pass. The true strain is 1~10 or even higher. As described in the foregoing technical solution, the method of the severe plastic deformation proposed by the present invention is simple in principle and easy to obtain, and can be realized in a general pressure processing factory and a plastic forming laboratory.

(2) It is easy to generate high hydrostatic pressure inside the tubular workpiece by using the beveling effect of the tipping principle, so that the material can be processed widely and the processing ability is strong. As described in the background art above, the high-pressure shearing method proposed by the present invention does not directly pressurize the tubular material axially, and does not restrain the end of the workpiece. Therefore, there is no central pressure that may occur after the workpiece is too long. Insufficient, pressure instability and other issues. Hydrostatic pressure can be generated more evenly inside the material up to 15 GPa. This is currently not possible with other processes including HPTT. Moreover, with the development of mold materials and the improvement of design, the hydrostatic pressure that can be provided will be higher. Plastic deformation under such high hydrostatic pressure conditions effectively suppresses the generation and development of material surfaces and internal cracks, thereby improving the workability of many difficult-to-machine materials such as magnesium alloys with poor plasticity. It is well known that materials such as magnesium alloys are densely packed due to the crystal structure, and the slip coefficient is limited, and the plasticity is often poor. When ARB or ECAP is processed on difficult-to-deform materials such as magnesium alloy, the sample often cracks. In order to avoid cracking, it is often necessary to increase the processing temperature, which will inevitably increase the processing cost. More importantly, as the processing temperature increases, the grain refining effect of the material becomes worse and the grains become coarser, which improves the material properties. The original intention is opposite. In contrast, the method can achieve plastic processing of many materials such as aluminum, copper, nickel, magnesium, titanium, tungsten and their alloys, and low carbon steel at room temperature or at a lower heating temperature, thereby controlling and improving. Its organizational structure improves its performance.

(3) The size of the tubular product that can be obtained is large. The method for realizing the high-pressure shearing of the pipe by using the tipping principle of the invention has a tubular shape, and the size thereof is limited only by the scale of the equipment. Even in the laboratory, the tubular material of ~100mm height can be obtained by this method, which has good performance and can be applied in many fields after a little subsequent treatment. In addition, the obtained tubular material is cut along the axial direction and is rolled. High performance sheeting is obtained.

DRAWINGS

Figure 1 is a schematic diagram of the principle of cumulative composite rolling (ARB) technology.

Figure 2 is a schematic diagram of the principle of equal channel angular extrusion (ECAP) technology.

Figure 3 is a schematic diagram of the principle of back pressure ECAP (BP-ECAP) technology.

Figure 4 is a schematic diagram of the principle of high voltage torsion (HPT) technology.

Figure 5 is a high-pressure tube twist Twisting-HPTT) Schematic diagram of the technical principle.

Figure 6 is a schematic diagram of the tip principle (or wedge effect, ramping force amplification principle). The so-called tip principle is shown in Figure 2. The input force is P, and the output force is N+N'=P/sinθ, where θ is half. Cone angle, when θ is small, the output force N+N'≈P/θ. This method of pressing the tubular workpiece by the principle of the inclined surface force is relatively uniform in loading, and the mold or the workpiece is not easily destabilized during the pressurization process.

7(a) to 7(d) are schematic diagrams showing the principle of the method for realizing high-pressure shearing of pipes by using the tip principle of the present invention, wherein 1-rigid mandrel, 2-rigid ring sleeve, 3-tube workpiece with taper h is the height of the tubular workpiece; r _i , r _e are the inner and outer radii of the lower end surface of the tubular workpiece; θ is the half cone angle; P is the main power provided by the press; T is the active torque provided by the power unit. The constrained reaction force and the constrained counter torque are not marked; the high pressure shear of the tubular specimen is achieved by applying the main power and the active torque shown in Figure 8 to the rigid collar and the mandrel or a combination thereof (the two main power directions are opposite in the figure). , respectively, acting on the rigid mandrel and the collar; the two active torques are opposite in direction, acting on the rigid collar and the mandrel respectively).

8(a) to (c) are schematic views of several constraint forms of the end portion of the workpiece of the present invention: the inner and outer walls of the workpiece are always constrained by a 1-rigid mandrel and a 2-rigid cuff, and (a) the end is unconstrained; (b) end semi-constraint; (c) end full constraint.

9 is a schematic view of a device for implementing a method for realizing high-pressure shearing of a pipe by using a tipping principle, wherein (a) is an exploded view: 90-upper head, 93-rigid mandrel, 95-tubular workpiece, 96-rigid ring sleeve, 97-ring sleeve gear, 98-thrust bearing, 100-mandrel base; in addition, the following features: 91-upper head lower square section Quadrangular prism, 92-rigid mandrel at the upper end of the square mandrel, 94-rigid mandrel at the lower end of the square section quadrangular prism, 99-core shaft base upper end square section recessed hole; (b) for assembly effect diagram.

Fig. 10 is a radial microhardness distribution diagram of an industrial pure aluminum tubular workpiece having a height of 30 mm, a half cone angle of 10°, a lower end surface radius r _i = 10 mm, and r _e = 14 mm after 25° shear deformation: From near the inner diameter to the outer diameter, the hardness changed from 48 HV (0.025kg) to 33 HV (0.025kg), showing a decreasing distribution trend, but higher than the sample 31 HV (0.025) which was not subjected to high-pressure shear deformation. Kg) hardness around.

Figure 11 is a cross-sectional optical microscopic metallographic diagram of a pure aluminum sample: (a) an initial extruded pure aluminum sample near the inner diameter of the anodic laminar polarized metallographic phase with an average grain size of about 40 μm; (b) high pressure shear After the deformation, the pure aluminum sample is close to the inner diameter of the anodic laminar polarized metallographic phase. The grain boundary of the deformed sample is not shown. No estimation of the average grain size is given, but it can be clearly seen that the grain is elongated and broken. Refined.

Embodiments of the invention

The material processing object of the present invention can be realized on a conventional extruder having a constant pressure function: the rigid ring is placed in the lower bottom plate or the lower pressing head plate. The tapered tubular workpiece is placed coaxially in a rigid collar that is connected to the upper or upper ram at a centered position and passes through the center of the tapered tubular workpiece. The rigid mandrel, the workpiece and the rigid ring sleeve are coaxially matched. After the rigid mandrel and rigid ring sleeve are coaxially assembled with the workpiece between the upper and lower plates (or indenters) of the press, displacement in the radial direction is not allowed (no horizontal displacement is allowed). The axial pressure provided by the press is then transmitted to the inner wall of the workpiece by a rigid mandrel or rigid collar attached to the upper and lower base plates (or rams). The inner wall of the workpiece is a small angle cone with respect to the axial direction. According to the principle of force amplification of the small angle slope (or wedge, cone, tip), the tubular workpiece generates a large pressure perpendicular to the inner or outer wall of the workpiece under the axial pressure. . The rigid ring sleeve and the mandrel constrain the radial deformation of the workpiece. At the same time, after the workpiece is pressed, there is a tendency to flow outward along the gap between the rigid collar and the mandrel. At this time, the friction generated by the contact surface between the workpiece and the rigid collar and the rigid mandrel, or the addition of a constraint at the end of the workpiece, hinders the flow of the substance. This design of applying high pressure to the inner and outer walls of the tubular workpiece while limiting its deformation and flow causes a high hydrostatic pressure (1 GPa to 15 GPa) to be accumulated inside the workpiece. Under high hydrostatic pressure conditions, although the shape change of the tubular workpiece is limited, it has a degree of freedom of rotation about the central axis. If one of the restraining bodies (the mandrel and the rigid collar, respectively) in contact with the inner wall or the outer wall of the workpiece is rotated about the central axis of the workpiece and the other is fixed, due to the large friction between the inner and outer walls of the workpiece and the device restraint There is a tendency for the material in the vicinity of the inner and outer walls of the workpiece to rotate or remain stationary with the binding body. Under high hydrostatic pressure conditions, in order to maintain the continuity of the material, the material of the tubular workpiece in different thickness layers in the radial direction will rotate at different angular velocities, that is, relative rotation occurs, and the material is sheared under the driving of friction.

The invention enables the tubular material to undergo shear plastic deformation under high hydrostatic pressure (up to ~15 GPa) (true should be up to 10~). Thereby, the plastic structure is controlled to control and optimize the structure of the material and improve its performance.

At the same time, the present invention only needs to install a simple combined mold composed of a rigid mandrel and a rigid ring sleeve on a conventional pressing device having a constant pressure function, that is, at a lower temperature (such as room temperature or lower). The heating temperature) achieves a new method of severe plastic deformation (SPD) processing - the use of the tipping principle (also known as the wedge effect or the principle of beveling force) to achieve high-pressure shearing of the pipe. The technology is highly feasible, there are no special requirements for operation, and the required equipment is simple and easy to obtain. At the same time, since the present invention is a new plastic working method realized by a conventional extrusion apparatus, the function of the conventional extrusion apparatus is expanded. The invention is suitable for experimental research and industrial production of bulk ultrafine crystal and nanocrystalline materials prepared by vigorous plastic deformation. With the present invention, high-performance metals, alloys, inorganic non-metallic materials, and polymer materials can be prepared. The method of using the tip of the tip to realize the high-pressure shearing of the pipe has a shape of a cone-shaped tube, which has high practical application potential and value.

The invention is further described in detail below with reference to the accompanying drawings.

Referring to Fig. 7(a), the present invention utilizes the tipping principle to realize the method of high pressure shearing of the pipe. First, the workpiece is processed, and the shape is a tapered pipe, and the inner wall and the outer wall of the workpiece are respectively restrained by the restraining body; then the inner wall is passed through the inner wall. The restraining body at the center applies axial main power to the inner wall of the workpiece (not shown in the constrained reaction force diagram). According to the principle of force amplification of the small angle inclined surface (or wedge, cone surface, tip), the workpiece is generated under the action of axial pressure. A large pressure perpendicular to the inner wall of the workpiece; the restraining body acts to restrain the radial deformation of the workpiece; at the same time, the friction generated by the contact surface between the workpiece and the rigid collar and the rigid mandrel, or the constraint at the end of the workpiece, hinders the substance Flow; this design that applies high pressure to the inner wall of the workpiece while limiting its deformation and flow causes a high hydrostatic pressure (1GPa~15GPa) to be accumulated inside the workpiece; then the active torque is supplied to the constraining body in contact with the outer wall of the workpiece (constrained anti-torque) Not shown in the figure), it rotates around the central axis of the workpiece, and at the same time, the constraint body that is in contact with the inner wall of the workpiece does not rotate, in the constraint The inner and outer walls of the workpiece frictional force, along the inside of the workpiece material at a radially varying thickness in different angular speed, in order to achieve the shear deformation of the workpiece.

Similarly, depending on the constraint body to which the active torque and the axial main power are applied, the implementation of the method principle also includes the manners of FIGS. 7(b), (c), (d) and the like. Moreover, the combination of these different implementations, such as the simultaneous application of axial main power to both constraints or the simultaneous application of active torque in opposite directions to the two constraints, will also achieve this principle. The specific text description and schematic diagram are omitted.

The invention utilizes a tipping principle to realize a device for high-pressure shearing of a pipe, comprising a press having a constant pressure function and a die having a transmission pressure, a constraining deformation and a rotating function; the mold comprises: a fixed or rotatable rigid mandrel 1 And a rigid sleeve 2 which can be rotated or fixed; the rigid mandrel 1 and the rigid collar 2 are respectively connected to the upper and lower bottom plates (or the upper and lower pressing heads) on the central axis of the press, and the tapered tubular workpiece 3 is the same The shaft is placed between the rigid mandrel 1 and the rigid cuff 2, and the outer wall of the rigid mandrel 1 and the inner wall of the rigid cuff 2 are respectively in contact with the inner and outer walls of the workpiece 3, and the taper of the contact surface is equal; the inner surface of the rigid cuff 2 is The outer surface of the rigid mandrel 1 is subjected to a special texturing treatment to control the friction with the workpiece 3 in accordance with the process requirements.

In the tubular material high-pressure shear deformation device of the present invention, at least one of the rigid mandrel 1 or the rigid cuff 2 is rotatable about a central axis, and the angle of rotation is not limited.

The tubular material high-pressure shear deformation device of the present invention can adopt a single-layer mold design, a pre-stress winding mold design or a pre-stress multi-layer mold design.

The specific implementation details and equipment operation of the new method of severe plastic deformation proposed in accordance with the present invention will be described below with reference to FIG. 7(a).

As shown in Fig. 7(a), the method of realizing the high-pressure shear of the pipe by the tipping principle (also called the wedge effect or the principle of the beveling force) is composed of a part including a 1-rigid mandrel and a 2-rigid ring. The mold, combined with a press with a pressure holding function, is realized on a 3-cone tubular workpiece.

First, the 2-rigid ring is placed in the lower or lower head pad. A 3-tapered tubular workpiece is placed concentrically in a rigid collar that is connected to the upper or upper ram at a centered position and passes through the center of the 3-tapered tubular workpiece. 1- rigid mandrel, 3-workpiece and 2-rigid ring set are coaxially matched. 1- The outer surface of the rigid mandrel is in contact with the inner wall of the 3-workpiece, and the inner surface of the 2-rigid collar is in contact with the outer wall of the 3-workpiece.

The press then presses the 1-rigid mandrel and maintains the pressure constant at a certain value. 1-In the process of axially lower displacement of the rigid core, axial pressure is generated on the inner wall of the 3-workpiece. According to the principle of small-angle inclined surface (or wedge surface, tapered surface, tip), the workpiece is axially pressurized. Under the action, it generates a huge pressure perpendicular to the inner wall; 1- rigid mandrel and 2-rigid ring sleeve constrain the 3-piece radial deformation; at the same time, 3-worker has a 1-rigid mandrel, 2-rigid ring The tendency of the gap to flow outward between the sleeves; thus, at the contact surface of the 3-workpiece with the 1-rigid mandrel and the 2-rigid collar, a frictional force in the opposite direction to the tendency of the material flow is generated, hindering the flow of the substance; The design of the high pressure of the inner wall of the workpiece, while limiting its deformation and flow, creates a high hydrostatic pressure inside the 3-workpiece (up to 15 GPa). Applying a tangential thrust to the 2-rigid collar, rotating it under the action of torque, while the 1-rigid mandrel does not rotate, in the 2-rigid collar and 3-workpiece and 1-mandrel and 3 - Under the action of the friction between the workpieces, the 3-piece will undergo shear deformation along the tangential direction. As the angle of rotation increases, the amount of shear deformation increases cumulatively, thereby effectively controlling and optimizing the microstructure of the material and improving its performance.

In addition, this principle can also be achieved by making certain changes to the equipment or mold and changing the pressure and rotating mold parts. As shown in Figure 7(d): Applying axial compression to the outer wall of the 3-workpiece using a 2-rigid collar, rotating the 1-rigid mandrel and fixing the 3-rigid collar provides similar shear plasticity to the tapered tubular material. Deformation effect. For the same reason, in the case of 7(b) and (c), the principle of the method of using the tip of the tip to realize the high-pressure shearing of the pipe is omitted.

On the other hand, according to the constraint of the end of the tubular workpiece, it can be divided into three cases as shown in Fig. 8: (a) the end is unconstrained; (b) the end semi-constraint; (c) the end full constraint. For the case where the 3-workpiece end is unconstrained, as shown in Fig. 8(a), the flow of the 3-workpiece end material will be completely limited by the frictional force in the opposite direction to the material flow tendency; for the 3-workpiece end In the case of semi-constraint, as shown in Fig. 8(b), the annular shoulder on the 1-mandrel and the annular shoulder on the 2-rigid ring respectively constrain the upper and lower ends of the 3-workpiece. There is a large gap between the annular shoulder and the 2-rigid ring sleeve to avoid rigid contact. Similarly, there is a large gap between the annular shoulder on the 2-rigid ring and the 1-rigid mandrel. The material flow at the same place is also limited by friction; for the case where the 3-piece end is fully constrained, as shown in Fig. 8(c), 4-, 5-ring washers are added to the upper and lower ends of the 3-workpiece, respectively. The 5-gasket uses a solid-state pressure transmitting medium, and the axial expansion of the inner and outer walls of the gasket will effectively hinder the material flow of the material at the end of the workpiece. In the foregoing, a detailed description of the principles of the present invention, for the sake of brevity, the four schematics used in Figure 7 all employ a simple design with unconstrained ends.

The present invention will be further described in detail below in conjunction with specific embodiments.

As shown in Fig. 9, the method principle realization device for realizing high-pressure shearing of pipe by using the tipping principle (also called wedge effect or the principle of beveling force increase) is shown. Figure 9(a) is an exploded view of the device, detailing the composition of the device.

90-upper head, 93-rigid mandrel, 95-tubular workpiece, 96-rigid ring sleeve, 97-ring sleeve gear, 98-thrust bearing, 100-mandrel base form the principle realization part of the whole device. The 96-rigid ring is placed on the lower bottom plate of the press and connected to the 98-thrust bearing between the bottom plate of the press. The 98-thrust bearing receives the axial pressure from the 96-rigid ring and reduces the axial pressure. The obstruction of the rotation of the 96-rigid ring around the shaft. The tapered 95-tube workpiece is placed concentrically in the 96-rigid collar. 91-The lower end of the upper indenter square prismatic prism and the 92-rigid mandrel upper end square section of the recess to achieve clearance fit, so that the 90-upper head and 93-rigid mandrel in the press axis position contact, and from the taper The center of the 95-tubular workpiece passes through, and the 90-upper head is bolted to the upper plate of the press. 93-rigid mandrel, 95-workpiece and 96-rigid ring set are coaxially matched. 93-Rigid mandrel, 96-rigid ring sleeve and 95-workpiece are coaxially assembled between the upper and lower plates of the press, and no displacement in the radial direction is allowed (no horizontal displacement is allowed). The 93-rigid mandrel then transfers the axial pressure provided by the press to the 95-worker inner wall through a 90-upper head attached to the upper plate of the press. 95-The inner wall of the workpiece is a small angle cone with respect to the axial direction. According to the principle of small angle inclined surface (or wedge surface, cone surface, tip), the 95-tubular workpiece will be produced perpendicular to the inner wall or outer wall of the 95-workpiece. It is much larger than the positive pressure of the axial load provided by the press. The 96-rigid collar and the 93-core shaft constrain the 95-workpiece radial deformation. At the same time, the 95-end of the workpiece is unconstrained, and the material has a tendency to flow outward along the gap between the 96-rigid collar and the 93-mandrel. This tendency is hindered by the friction in the opposite direction. This design adds a high hydrostatic pressure (1GPa~15GPa) inside the 95-workpiece. At the same time, the servo motor is used to drive the reducer gear set (the power unit adopts the conventional motor and gear set or the worm gear of the appropriate power and speed, the schematic diagram is omitted) to drive the 97-ring sleeve gear, and rotate it under the action of the torque. The rotation speed is 1~5rpm. Due to the friction, the material at the 95-work outer wall will have a tendency to rotate with the 97-rigid collar. The concave hole of the square end section of the upper end of the 92-rigid mandrel is constrained by the square cross section of the upper end of the 91-upper head, and the square prism of the lower end of the 94-rigid mandrel is constrained by the concave hole of the upper end of the 99-core shaft base, 95- The material at the inner wall of the workpiece will have a tendency to be fixed together with the 93-rigid mandrel; under high hydrostatic pressure conditions, the material will remain continuous, and the 95-tubular workpiece will rotate at different angular velocities along different layers of the radial thickness. That is, relative rotation occurs, and the material is shear-driven under the driving of friction.

In this embodiment, the 93-rigid mandrel adopts a design in which the upper and lower ends simultaneously constrain the rotational freedom. The constraining method adopts two sets of square-section quadrangular prisms and square-section recessed holes (91-, 92-, and 94-, 99-). The clearance fit is achieved. The F7/h6 base shaft clearance fit and the H7/g6 base hole clearance fit are used between the two sets of square-section quadrangular prisms and square-section recessed holes (91-, 92- and 94-, 99-). On the one hand, the 93-core shaft is easy to fix, on the other hand, the 93-core shaft is simultaneously subjected to force at both ends, and the fracture is broken due to excessive torque. In addition, the 90-upper head does not directly contact the 95-tubular workpiece, and the pressure is 93-rigid mandrel directly transmitted to the inner wall of the workpiece. This design is because the part directly in contact with the end face of the workpiece is subjected to a very bad force. It is necessary to add an annular gasket made of cemented carbide to increase the cost; on the other hand, when the end of the 95-workpiece is directly pressurized, due to friction The presence of pressure does not pass evenly to the middle of the 95-workpiece, causing insufficient pressure in the middle, often limiting the height of the 95-workpiece. The method for realizing high-pressure shearing of the pipe by using the tip principle of the patent can effectively overcome the above disadvantages.

When the 96-rigid ring sleeve is designed with prestressed winding mold, the inner layer selects materials with high hardness and toughness, such as die steel; the wound layer uses high toughness materials, such as spring steel wire or spring steel strip; the outer layer adopts toughness. Higher material, such as medium carbon steel. When the 96-rigid ring sleeve is designed with prestressed multi-layer ring sleeve, the inner layer selects materials with higher hardness and toughness, such as die steel; the other layers select materials with higher toughness, such as medium carbon alloy steel or die steel. The 92-rigid mandrel is inlaid with hard alloy, and the rest is made of die steel.

The specific materials are as follows: the mold steel is Cr5Mo1V steel; the spring steel is 65Mn steel; the medium carbon steel is 45 steel; the medium carbon alloy steel is 45Mn steel; the hard alloy is YG6A.

In this embodiment, the assembled effect of the device for achieving high pressure shear of the pipe using the tip principle is as shown in Fig. 9(b).

Through the scheme, preliminary experimental research on industrial pure aluminum, 6063 aluminum alloy and AZ31 magnesium alloy tubular workpiece was carried out.

The workpiece has a height of 30 mm, a half cone angle of 10°, a lower end surface radius r _i = 10 mm, and r _e = 14 mm.

The radial microhardness distribution of the industrial pure aluminum tubular workpiece after 25° shear deformation is shown in Figure 10: from near the inner diameter to near the outer diameter, the hardness is changed from 48 HV (0.025 kg) to 33. HV (0.025kg), showing a decreasing distribution trend, but higher than the initial sample 31 without high-pressure shear deformation Hardness around HV (0.025kg). The cross-section optical microscopic metallographic phase of the sample is shown in Figure 11: Figure 11 (a) The initial extruded pure aluminum sample is observed near the inner diameter of the anodic lamination, and the average grain size is about 40 μm; (b) high-pressure shear deformation After the pure aluminum sample is close to the bright field phase at the inner diameter, some grain boundaries are not shown in the bright field phase, and the average grain size is not given. However, it can be clearly seen that the grain is elongated, broken and refined. (c) The microstructure of the pure aluminum sample from the inner diameter to the outer diameter after high-pressure shear deformation.

In addition, the experimental results of 6063 aluminum alloy and AZ31 magnesium alloy are briefly summarized as follows:

The average grain size of 6063 aluminum alloy before high pressure shear is 80μm, the compression test yield strength is 156.8MPa; the high pressure shear deformation of 60o is achieved by the tipping principle of 2.5GPa hydrostatic pressure at 1rpm. The average strain reaches 3.1. The average grain size reached 746 nm, and the compression test yield strength increased to 402.6 MPa.

The plasticity of AZ31 magnesium alloy is poor, and we heat the mold at 100 °C. The average grain size before the high pressure shear was 27 μm, the compression test yield strength was 276.4 MPa; the high pressure shear deformation of the tubular material achieved by the tip principle of 90° at a rotational speed of 1 rpm at 3 MPa hydrostatic pressure, the average strain reached 4.7, the average grain size reached 640 nm, and the compression test yield strength increased to 396.5 MPa.

Claims

The invention relates to a method for realizing high-pressure shearing of a pipe by using a tipping principle, which is characterized in that: firstly, the processed workpiece is selected to have a tapered tubular shape, and the inner wall and the outer wall of the workpiece are respectively restrained by the binding body; then the shaft is applied to the binding body To the pressure, the axial pressure is increased by the force-increasing principle of the tip and converted into a positive pressure perpendicular to the contact surface of the workpiece to obtain a high hydrostatic pressure in the workpiece; then a torque is provided to a restraining body so that Rotating around the central axis of the workpiece and fixing the other binding body; or simultaneously providing the opposite directions to the two binding bodies such that they rotate relative to each other about the central axis of the workpiece; the tangential friction between the binding body and the inner and outer walls of the workpiece Under the action, the materials at different thicknesses in the radial direction of the workpiece rotate at different angular velocities, thereby achieving shear deformation of the workpiece.
The method for realizing high pressure shearing of a pipe using the tip principle according to claim 1, wherein the high hydrostatic pressure is 1 to 15 GPa.
A device for realizing high-pressure shearing of a pipe by using a tipping principle, comprising: a press having a constant pressure function and a die having a transmitting pressure, a constraining deformation, and a partial rotating function; the die includes an axially movable or a rotating rigid mandrel (1) and a rotatable or axially moveable rigid collar (2); the rigid mandrel (1) and the rigid collar (2) are respectively disposed on the upper and lower plates of the press, The workpiece (3) is coaxially placed in the rigid ring sleeve (2), the inner surface of the rigid ring sleeve (2) is in contact with the outer wall of the workpiece (3), and the inner portion of the workpiece (3) is coaxially provided with a rigid core shaft (1). The outer surface of the rigid mandrel (1) is in contact with the inner wall of the workpiece (3).
The apparatus for realizing high-pressure shearing of a pipe by the tipping principle according to claim 3, characterized in that the inner surface of the rigid collar (2) and the outer surface of the rigid mandrel (1) are subjected to texturing treatment.
The apparatus for realizing high-pressure shearing of a pipe by using a tipping principle according to claim 3, wherein at least one of the rigid mandrel (1) and the rigid collar (2) is axially movable to complete Pressurize action.
The apparatus for realizing high-pressure shearing of a pipe by using a tipping principle according to claim 3, wherein one of the rigid collar and the rigid mandrel is rotatable, or both can be rotated in opposite directions at the same time, the angle of rotation No limit.
The apparatus for realizing high-pressure shearing of a pipe using the tip principle according to claim 3, wherein the rigid ring sleeve (2) adopts a single-layer mold design, a pre-stressed winding mold design or a pre-stressed multilayer mold design.
The device for realizing high pressure shearing of a pipe using the tip principle according to claim 3, characterized in that the end constraint of the workpiece (3) can adopt an unconstrained, semi-constrained or fully constrained design.