CN106238488A - Different pressures cut the method and apparatus of continuous large plastometric set under composite strain path - Google Patents

Abstract

The invention relates to the technical field of plastic forming, in particular to a method and device capable of realizing continuous large plastic deformation under different compressive-shear composite strain paths. The invention introduces uniform shearing deformation into the material through the design of the bending die, and under the compression fit in other directions, it can conveniently realize pure shearing, one shearing and one pressing, one shearing and two pressings, one shearing and three pressings in the material, etc. Various deformation states. Moreover, through the single-pass deformation of the multi-bending section bending mold or the multi-pass deformation of the single-bending section bending mold, the accumulation of acute plastic deformation can be effectively realized. The invention can realize continuous deformation processing of metal plates and rods, and the prepared materials can have ultra-fine crystal or even partial nano crystal structure.

Description

Method and device for continuous large plastic deformation under different compression-shear composite strain paths

technical field

The invention relates to the technical field of plastic forming, in particular to a method and device capable of realizing continuous large plastic deformation under different compressive-shear composite strain paths.

Background technique

The large plastic deformation (SPD) processing technology is currently a commonly used plastic processing method for the preparation of high-performance metal materials and components. Compression-shear (referred to as compression-shear) composite deformation is a kind of SPD processing technology, which is often used to prepare materials with ultrafine crystals and even partial nanocrystals. During the forming process, shear deformation can effectively refine the grain structure and improve the performance of materials and components. Currently existing compression-shear processes mainly include high-pressure torsion (HPT), equal-channel extrusion (ECAP), rotary die extrusion (TE) and other processes, but they all have large extrusion force, limited material preparation size, and uniform deformation. Poor and other shortcomings. In addition, after shear deformation under high pressure, although the crystal grains are obviously refined, the requirements for the forming device are high, and a torsion unit needs to be added to the original pressure mechanism. The process is relatively complicated, and the shear deformation is only concentrated. on the sample surface.

In order to overcome the above disadvantages, Patent Publication No. CN102430609A proposes an equal-channel variable-section extrusion die, which can realize compression-shear deformation by using section torsion changes, but this method is only applicable to pipe processing. Patent Publication Nos. CN102699084A and CN104399771A both propose that cup-shaped parts and cylindrical parts with ring-shaped inner ribs can be processed by using the composite deformation process of rotation and extrusion, and the forming performance of materials can be significantly improved through material compression-shear deformation, and can significantly increase etc. Effective plastic strain and refined grain structure. Material preparation using compression-shear deformation, currently commonly used methods include the reciprocating extrusion process proposed by ECAP and CN 101966536A, but both have disadvantages such as large extrusion force, limited size of processed billet, uneven shear deformation, etc., and the mold processing is more complicated .

Contents of the invention

The purpose of the present invention is to provide a method and device that can realize continuous large plastic deformation under different compression-shear composite strain paths. The method and device are suitable for metal plates and bars. Through the design of the bending die, uniform Shear deformation, under compression and coordination in other directions, can easily realize various deformation states such as pure shear, one shear and one compression, one shear and two compression, one shear and three compression. Moreover, through multiple bending sections or multiple passes of deformation, the accumulation of acute plastic deformation can be effectively realized, and the continuous deformation processing of the material can be easily realized, and the prepared material can have an ultrafine crystal or even a nanocrystalline structure. Among them, one-shear-compression refers to the shear and compression deformation in the thickness direction. One shear and two compression refers to the shear and compression deformation in the thickness direction, as well as the lateral compression deformation, and one shear and three compression refers to the shear and compression deformation in the thickness direction, as well as the lateral and longitudinal compression deformation.

Technical scheme of the present invention is as follows:

A device for continuous large plastic deformation under different compression-shear composite strain paths. The device is equipped with an upper mold, a lower mold and a feeding mechanism. Fixed, the blank is located between the upper mold and the lower mold; the corresponding surfaces of the upper mold, the lower mold and the blank include: the upper flat section, the lower flat section, the curved section, the upper flat section and the lower flat section The transition is connected by a curved section, the upper flat section and the curved section adopt a rounded transition, and the lower flat section and the curved section adopt a rounded transition.

In the device for continuous large plastic deformation under different compressive-shear composite strain paths, the right extrusion die and the left extrusion die are respectively arranged on both sides of the billet.

In the device for continuous large plastic deformation under different compressive-shear composite strain paths, the length of the flat section corresponding to the mold and the blank is L ₁ =L ₃ =30-50 mm, and the bending between the upper flat section and the lower flat section is Segment length L ₂ =10~30mm, the included angle between the flat section and the curved section is θ=100~160°, the fillet R ₁ between the upper flat section and the curved section is 2~6mm, the lower flat section The fillet R ₂ between the segment and the curved segment = 1-5 mm.

The method for continuous large plastic deformation under different compression-shear composite strain paths of the device, the specific steps are as follows:

(1) Compression-shear deformation mold design, according to material preparation and processing needs, determine the main deformation parameters of the key bending section of the mold;

(2) Overall mold design, determine the parameters of other bending sections, mainly the size of the flat section, and the corresponding movement speed of each mold;

(3) Select a press for mold assembly with the molds designed in (1) and (2);

(4) Use the mold assembled in (3) to carry out compression-shear deformation processing of the billet, and perform single-pass or multi-pass deformation as required.

The method of continuous large plastic deformation under different compressive-shear compound strain paths, through the design of the mold device, introduces uniform shear deformation into the material, and under the compression fit in other directions, it can conveniently realize pure shear and one-dimensional deformation in the material. One-shear, two-shear or three-shear deformation states; through single-pass deformation of multi-bending section bending mold or multi-pass deformation of single-bending section bending mold, the accumulation of severe plastic deformation can be effectively realized, and it is convenient to realize the material Continuous deformation processing, the prepared material has ultrafine crystal or even nanocrystalline structure.

The method of continuous large plastic deformation under different compression-shear composite strain paths relies on the closed fit of the upper and lower mold bending sections to form uniform shear deformation in the processed material, and through the critical dimension of the compression-shear deformation zone, the thickness of the blank The directions introduce varying degrees of uniform shear deformation.

The method of continuous large plastic deformation under different compression-shear composite strain paths, in the case of using other molds to cooperate, realizes pure shear, one shear and one compression, one shear and two compression, or one shear and three compression deformation states in the deformation area of the mold. ; Among them, one shear and one compression refers to the shearing and compression deformation in the thickness direction; one shearing and two compressions refer to the shearing and compression deformation in the thickness direction, and lateral compression deformation; one shearing and three compressions refer to the shearing and compression deformation in the thickness direction , and lateral and longitudinal compression deformation.

The method of continuous large plastic deformation under different compressive-shear composite strain paths can be realized by arranging multiple bending sections on the mold, relying on single-pass deformation-multi-bending sections to accumulate deformation, or performing multi-pass processing on the blank Accumulated plastic deformation.

The method for continuous large plastic deformation under different compressive-shear composite strain paths is suitable for bar processing or plate processing, and for processing large-sized plates with different thicknesses, and the feeding method is continuous feeding processing, so as to realize plate and bar processing. continuous processing of materials.

Advantage of the present invention and beneficial effect are as follows:

(1) The present invention can conveniently realize multiple deformation states such as pure shear, one shear and one compression, one shear and two compressions, one shear and three compressions in the deformation zone through lateral die extrusion.

(2) The present invention introduces uniform compression and shear deformation in the main deformation zone through the cooperation of the upper and lower molds.

(3) The present invention can be applied to the processing of rods and plates, and the plates are basically not limited by the width and thickness of the plates.

Description of drawings

Figure 1 is a schematic diagram of the sheet metal compression shearing process.

Figure 2 is a schematic diagram of the bar compression shearing process.

Fig. 3 (a) is the AA section of Fig. 2 and the schematic diagram of the key dimensions of the present invention (including the lengths L ₁ , L ₂ and L ₃ of the flat section and the angle θ of the curved section, and the fillets R ₁ and R ₂ ); Fig. 3 (b) It is a schematic diagram of the BB section in Figure 2, the mold cavity size R ₃ and the blank diameter Φ.

Fig. 4 is a diagram of a device for realizing different deformation states.

Figure 5 shows the numerical simulation results of the sheet shear strain.

Figure 6(a) and Figure 6(b) are comparison diagrams of shear strain uniformity along the thickness direction (Line 1 in Figure 5) and along the transverse direction (Line 2 in Figure 5), where the abscissa Distance is the distance S( mm); the ordinate Shear strain is the shear strain γ ₁₂ .

In the figure, 1-upper die; 2-billet; 3-lower die; 4-right extrusion die; 5-left extrusion die; 6-flat section I; 7-curved section; 8-flat section II.

detailed description

In the specific implementation process, in order to overcome the shortcomings of the traditional compression-shearing process, such as large load, limited processing blank size, uneven shear deformation, continuous processing, and difficulty in adjusting the compression-shear composite deformation path, it is necessary to propose a method that can It is a compression-shearing process that realizes the preparation and processing of large-scale materials, and has the advantages of small load and uniform shear deformation. On the other hand, in order to effectively refine the material structure, the method and device should also realize the effective accumulation of severe plastic deformation and the adjustable compression-shear composite deformation path, so as to realize the ultrafine crystal or even nanocrystalline structure of the prepared material. The specific steps as follows:

(1) Design of compression shear deformation die. According to the material preparation and processing needs, determine the main deformation parameters of the key bending section of the mold. The main parameters include bending angle, fillet, length of flat section, etc.

(2) Overall mold design. It is necessary to determine the parameters of other bending sections, mainly the size of the flat section, and the design of molds in other directions according to the deformation state, as well as the corresponding movement speed of each mold.

(3) Select a suitable press for the molds designed in (1) and (2) to assemble the molds.

(4) Use the mold assembled in (3) to carry out the plate or plate compression shear deformation processing, and can flexibly perform single-pass and multi-pass deformation according to needs.

This method mainly relies on the closed fit of the main bending sections of the upper and lower molds, which can form a uniform shear deformation in the processed material. This method can introduce different degrees of uniform shear deformation in the thickness direction of the plate through the key dimension of the compression shear deformation zone. The method can conveniently realize various deformation states such as pure shearing, one shearing and pressing, one shearing and two pressings, and one shearing and three pressings in the deformation area of the mold under the condition of using other molds to cooperate. Accumulation of severe plastic deformation in this method can be achieved by arranging multiple bending segments on the mold, relying on single-pass deformation-multi-bending segments to accumulate deformation or performing multi-pass processing on the blank to accumulate deformation. This method is not only suitable for bar processing, but also for plate processing, where the size restriction on the plate is small, that is, large-sized plates with different thicknesses can be processed. The feeding mode of the method can be continuous feeding processing, which conveniently realizes continuous processing of plates and bars.

The processing and principle of the present invention will be described in detail below in conjunction with specific embodiments.

Example 1

The invention is not only suitable for bar processing, but also can be used for plate processing. This embodiment takes sheet material processing-shearing-pressing deformation as an example for illustration, and the mold equipment and sheet forming results are shown in Figure 1, Figure 5, Figure 6(a) and Figure 6(b). Referring to Fig. 1 and Fig. 3 (a), the device is provided with an upper die 1, a lower die 3 and a feeding mechanism, the upper die 1 is fixed to the upper die base, the lower die 3 is fixed to the lower die base, and the blank 2 is fixed to the feeding mechanism , the blank 2 is located between the upper mold 1 and the lower mold 3; the corresponding surfaces of the upper mold 1 and the lower mold 3 respectively and the blank 2 include: the flat section I6 located in the upper part, the flat section II8 located in the lower part, and the curved section 7 located in the upper part The transition between the flat section I6 and the lower flat section II8 is connected by a curved section 7, the upper flat section I6 and the curved section 7 adopt a rounded transition, and the lower flat section II8 and the curved section 7 adopt Rounded transitions.

In this embodiment, the specific steps of plate processing-shearing-compression deformation are as follows:

Step 1: Mold parameter design. The parameters in this embodiment are mainly as follows, the thickness H ₂ of the plate is preferably ≥5 mm, the length and width of the plate are not limited, and the thickness of the plate H ₂ =10 mm. The mold parameters are as follows (L ₁ , L ₂ , L ₃ , R ₁ , R ₂ , θ, flat section Ⅰ6, curved section 7, and flat section Ⅱ8 refer to Figure 3(a)), the flat section corresponding to the mold and the plate (flat section Ⅰ6, flat section Ⅱ8) length L ₁ =L ₃ =40mm, the length of the curved section 7 between the upper flat section Ⅰ6 and the lower flat section Ⅱ8 is L ₂ =15mm, and the angle between the flat section and the curved section is θ=150°, the rounded angle R ₁ between the upper flat section I6 and the curved section 7 =3mm, and the rounded angle R ₂ between the lower flat section II8 and the curved section 7 =2mm.

Step 2: Mold assembly. The mold device involved in this embodiment includes an upper mold, a lower mold and a feeding mechanism, wherein the upper mold 1 is fixed to the upper mold base, the lower mold 3 is fixed to the lower mold base, the blank 2 is fixed to the feeding mechanism, and the blank 2 is located on the upper mold base. Between mold 1 and lower mold 3.

Step 3: Initial compression-shear deformation. In the initial stage of forming, the mold needs to be subjected to the first step of compression-shear deformation, that is, the upper mold 1 is pressed down at a speed V ₁ (in this embodiment, V ₁ =4mm/s), and the blank 2 undergoes compression-shear deformation during the pressing process, and It fits with the lower mold 3 to complete the initial compression-shear deformation step, and the feeding mechanism does not move during this process.

Step 4: Continuous compression-shear deformation. In the continuous deformation process, the basic process is shown in step 3. The upper mold 1 is opened upwards, and the blank is fed with the help of the auxiliary mechanism. After the feeding is completed, the auxiliary feeding mechanism remains stationary, and the upper mold 1 is pressed down by the press to perform compression shearing. out of shape. Continuous compression-shear deformation can be achieved by repeating step 4.

As shown in Figure 5, it can be seen from the numerical simulation results of the plate compression shear deformation that the accumulation of uniform strain can be effectively realized through the reasonable design of the mold. As shown in Figure 6(a) and Figure 6(b), from the shear strain distribution diagrams along the thickness direction and at different distances in the cross section, it can be seen that the shear strain in the thickness direction can be obtained at other positions except the surface layer is affected by friction. The shear strain in the thickness direction is evenly distributed along the cross-section.

Example 2

As shown in Fig. 2, Fig. 3(a) and Fig. 3(b), in this embodiment 2, the bar compression-shearing process is also taken as an example to illustrate the basic process and principle of realizing the one-shear and two-compression stress state in the plate. The device is equipped with an upper mold 1, a lower mold 3 and a feeding mechanism. The upper mold 1 is fixed to the upper mold base, the lower mold 3 is fixed to the lower mold base, and the blank 2 is fixed to the feeding mechanism. The blank 2 is located between the upper mold 1 and the lower mold. Between 3; the corresponding surfaces of the upper die 1 and the lower die 3 and the blank 2 include: the upper flat section I6, the lower flat section II8, and the curved section 7, the upper flat section I6 and the lower flat section The transition between II8 is connected by the curved section 7, the rounded transition is adopted between the upper flat section I6 and the curved section 7, and the rounded transition is used between the lower flat section II8 and the curved section 7.

The mold parameters are as follows (L ₁ , L ₂ , L ₃ , R ₁ , R ₂ , θ, flat section Ⅰ6, curved section 7, and flat section Ⅱ8 refer to Figure 3(a)), the flat section corresponding to the mold and the plate (flat section Ⅰ6, flat section Ⅱ8) length L ₁ =L ₃ =40mm, the length of the curved section 7 between the upper flat section Ⅰ6 and the lower flat section Ⅱ8 is L ₂ =15mm, and the angle between the flat section and the curved section is θ=150°, the rounded angle R ₁ between the upper flat section I6 and the curved section 7 =3mm, and the rounded angle R ₂ between the lower flat section II8 and the curved section 7 =2mm.

In this embodiment, the parameters of the main bending section of the mold are the same as in Embodiment 1, and the process is basically the same. Here, only the differences between Embodiment 1 and Embodiment 2 will be described. The differences between Embodiment 2 and Embodiment 1 in:

(1) For bar processing, it is necessary to use a mold with a mold cavity to maintain the shape of the bar during the compression-shear deformation process.

(2) The mold fit is involved in the loading process, wherein the radius of the mold cavity R ₃ ≤ the diameter of the bar Φ, the pressing speed of the upper die V ₁ , and the different compression-shear strain paths are realized through the size ratio of the mold and the bar.

Example 3

In this embodiment 3, the basic process and principle of realizing the one-shear and three-compression stress state are also described by taking the compression-shear processing of a plate as an example, as shown in FIG. 4 . Referring to Figure 3(a) and Figure 4, the device is provided with an upper mold 1, a lower mold 3 and a feeding mechanism, the upper mold 1 is fixed to the upper mold base, the lower mold 3 is fixed to the lower mold base, and the blank 2 is fixed to the feeding mechanism , the blank 2 is located between the upper die 1 and the lower die 3, and the right extrusion die 4 and the left extrusion die 5 are arranged on both sides of the blank 2 respectively; : The upper flat section I6, the lower flat section II8, and the curved section 7, the upper flat section I6 and the lower flat section II8 are connected and transitioned by the curved section 7, the upper flat section I6 and the curved section 7 adopts rounded corner transition, and adopts rounded corner transition between the lower flat section II 8 and the curved section 7 .

The mold parameters are as follows (L ₁ , L ₂ , L ₃ , R ₁ , R ₂ , θ, flat section Ⅰ6, curved section 7, and flat section Ⅱ8 refer to Figure 3(a)), the flat section corresponding to the mold and the plate (flat section Ⅰ6, flat section Ⅱ8) length L ₁ =L ₃ =40mm, the length of the curved section 7 between the upper flat section Ⅰ6 and the lower flat section Ⅱ8 is L ₂ =15mm, and the angle between the flat section and the curved section is θ=150°, the rounded angle R ₁ between the upper flat section I6 and the curved section 7 =3mm, and the rounded angle R ₂ between the lower flat section II8 and the curved section 7 =2mm.

In this embodiment, the parameters of the mold are the same as those in Embodiment 1, and the process is basically the same. Here, only the differences between Embodiment 3 and Embodiment 1 will be described. The differences between Embodiment 3 and Embodiment 1 are:

(1) In order to realize the one-shear and three-compression stress state, it needs to be completed with the assistance of the movement speed V ₂ of the right extrusion die 4 and the left extrusion die 5, and the auxiliary effect of the pressure F at both ends of the billet.

(2) Die matching is involved in the loading process, wherein the thickness H ₁ of the right extrusion die 4 and the left extrusion die 5 ≤ the thickness H ₂ of the plate, the pressing speed V ₁ of the upper die and the right extrusion die 4, The lateral pressure velocity V ₂ of the left extrusion die 5 can achieve different ratios, thereby realizing different compression-shear strain paths (in this embodiment, V ₁ =3 mm/s, V ₂ =2 mm/s).

It should be noted that the material for deformation processing is not limited in the present invention. This process can not only process common metal materials (iron, magnesium, copper, aluminum, etc.), but also can be used for processing metal matrix composite materials.

Claims (9)

1. different pressures cut the device of continuous large plastometric set under composite strain path, it is characterised in that: this device is provided with Mould, lower mold and feed mechanism, upper mold fixes with upper bolster, and lower mold is fixed with die shoe, and blank is fixed with feed mechanism, Blank is between upper mold and lower mold；Upper die and lower die include with the corresponding surface of blank: superposed smooth section, be positioned at bottom Smooth section, bending section, superposed smooth section is connected transition with between smooth section of bottom by bending section, is positioned at Use round-corner transition between smooth section and the bending section on top, between smooth section and bending section of bottom, use fillet mistake Cross.

Different pressure the most according to claim 1 cuts the device of continuous large plastometric set under composite strain path, and its feature exists In, the both sides of blank are respectively provided with right side extrusion die and left side extrusion die.

Different pressure the most according to claim 1 cuts the device of continuous large plastometric set under composite strain path, and its feature exists In, smooth segment length L that mould is corresponding with blank₁=L₃=30～50mm, superposed smooth section be positioned at the smooth of bottom Bending section length L between Duan₂=10～30mm, smooth section is θ=100～160 ° with the angle of bending section, is positioned at top Smooth section and bending section between fillet R₁=2～6mm, the fillet R between smooth section and bending section of bottom₂=1～ 5mm。

4. the different pressures using one of claim 1～3 described device cut continuous large plastometric set under composite strain path Method, it is characterised in that specifically comprise the following steps that

(1) press-shear deformation Design of Dies, according to material preparation and processing needs, determines the primary deformable ginseng of mould key bending section Number；

(2) unitary mould design, determines meeting the tendency mutually of the parameter of other bending sections, the most smooth section of size, and each mould Dynamic speed；

(3) mould (1) and (2) designed, selection pressure machine carries out die assembly；

(4) utilize the mould assembled in (3) to carry out blank press-shear deformation processing, carry out single pass as required or multi-pass becomes Shape.

Different pressure the most according to claim 4 cuts the method for continuous large plastometric set under composite strain path, and its feature exists In, by the design of die device, introduce uniform detrusion in the material, under other direction compressed fit, it is possible to side Realize pure shear the most in the material, one cut a pressure, one cut two pressures or and cut three compressive strain states；Through too much bending section bending mould list Passage deformation or single bending section bending mould multi-pass deformation, effectively realize the accumulation of Sever Plastic Deformation, and facilitate implementation material The continuous modification processing of material, prepared material has Ultra-fine Grained even nanocrystalline structure.

Different pressure the most according to claim 4 cuts the method for continuous large plastometric set under composite strain path, and its feature exists In, rely on the Guan Bi of upper/lower die bending section to coordinate, rapidoprint is formed uniform detrusion, and passes through press-shear deformation The critical size in district, introduces uniform detrusion in various degree in sotck thinkness direction.

Different pressure the most according to claim 4 cuts the method for continuous large plastometric set under composite strain path, and its feature exists In: in the case of utilizing other moulds to coordinate, realize pure shear in die deformation district, one cut a pressure, one cut two pressures or and cut three Compressive strain state；Wherein, one cut a pressure refer to thickness direction shear and compression；One cut two pressures refer to thickness direction shear and Compression, and lateral compression deformation；One cuts three pressures refers to that thickness direction is sheared and compression, and laterally and longitudinally presses Compression deformation.

Different pressure the most according to claim 4 cuts the method for continuous large plastometric set under composite strain path, and its feature exists In: by arranging multiple bending section on mould, rely on single pass deformation-many bending sections to carry out accumulated deformation, or blank is entered The processing of row multi-pass can realize Sever Plastic Deformation accumulation.

The most according to claim 4, different pressures cut the method for continuous large plastometric set under composite strain path, it is characterised in that: The method is applicable to bar processing or sheet fabrication, carries out the sheet fabrication of large scale different-thickness, and feed profile is for even Continuous feeding processing, it is achieved sheet material and the Continuous maching of bar.