Multi-inclined-hole die arc-shaped material extrusion forming device and method

Abstract

The invention provides a multi-inclined-hole die arc-shaped material extrusion forming device and a multi-inclined-hole die arc-shaped material extrusion forming method. The method is characterized in that a plurality of discretely distributed mold holes are prefabricated in a mold according to a certain distribution characteristic, the axis of each prefabricated hole and the extrusion axis form a certain angle, and meanwhile, the stress state and the flow behavior distribution situation of an extrusion material at a mold orifice can be influenced by adjusting the thickness of the mold; therefore, local acting force on the mold disc is dispersed, accumulated shear deformation borne by the blank is further increased, quantitative regulation and control over the microstructure, the curvature radius and the change characteristics of the extruded arc-shaped material are achieved, and the service life of the mold is remarkably prolonged. According to actual requirements, key process parameters such as the number, the axis included angle, the geometrical shape, the inlet and outlet layout extrusion ratio and the arrangement form of the prefabricated holes can be flexibly set, and the requirements of personalized and customized arc-shaped materials can be met; the process flow is greatly reduced, the production efficiency is obviously improved, the production cost is reduced, the surface quality and the shape and size precision of a formed product are obviously improved, and a plurality of high-performance arc-shaped material products with curvature characteristics can be directly and simultaneously extruded and formed at one time.

Description

Technical Field

[0001] The invention relates to an extrusion forming method of an arc-shaped material, and in particular to an extrusion forming device and method of an arc-shaped material with a multi-inclined hole die. Background Art

[0002] Curved materials are favored for their unique appearance design, excellent performance such as high aerodynamic efficiency, and their ability to meet the diverse needs of structure and function. At present, they have been widely used in aerospace, transportation, national defense and military industry, medical equipment and other fields. Their usage has been gradually increasing in recent years, providing a strong guarantee for safety and comfort. The traditional forming method of curved materials is mainly a two-step method of forming first and then bending, such as press bending, bending, rolling bending and CNC bending. It has bottlenecks such as lengthy process flow, high cost, low efficiency, and difficulty in controlling the shape and size precision. In addition, the formed products are often accompanied by defects such as wrinkling, springback, and cross-sectional distortion.

[0003] Through the optimization of die structure design and loading mode, the extrusion process can directly form and manufacture high-performance curved products in one step. In recent years, it has gradually become one of the ideal choices for the forming and manufacturing of high-performance curved products. Curved material extrusion forming methods such as lateral differential extrusion, variable channel corner self-bending extrusion, and eccentric die structure extrusion continue to emerge and be applied. The lateral differential extrusion method uses two extrusion rods with different speeds to form a speed difference in the material extruded from the side, and can extrude a curved profile with adjustable curvature along the length direction in a single extrusion process. However, the lateral differential extrusion involves a forming method of multi-directional extrusion and side discharge, which requires precise control of the extrusion speed and its ratio, which puts higher requirements on production equipment and process control; the variable channel angle self-bending extrusion method designs a streamlined extrusion cavity structure with a deformed central axis to make the metal flow unevenly in the cavity, thereby directly extruding a curved profile. However, due to its complex cavity structure, it is difficult to achieve quantitative control of the curvature of the formed part, thereby limiting the process flexibility; the eccentric die structure extrusion method is to set a certain eccentricity between the punch axis and the outlet axis, so that the material at the outlet of the extrusion die forms a velocity gradient, thereby inducing the material to bend and deform, but when the eccentricity is greater than a certain value, the curvature of the curved profile no longer changes significantly.

[0004] In response to the problem of uncontrollable curvature in the manufacture of curved materials, an invention patent with patent number CN201611003122.1 and publication date March 15, 2019 discloses an extrusion device for manufacturing extruded parts with variable curvature. This method controls the module by setting a double-acting mold at the discharge port, so that during the extrusion process, friction is generated between the molded part and the part of the module protruding from the discharge port, resulting in a difference in flow rate on both sides of the discharge port, thereby achieving the control of the curvature radius of the curved material. In response to the problems of low efficiency and poor dimensional accuracy in the manufacture of curved materials by traditional bending processes, the invention patent with patent number CN202010085303.3 and publication date November 5, 2021 discloses a porous self-bending extrusion die for profiles. This method connects multiple guide cavities with different geometric characteristics to make the metal flow unevenly, thereby adjusting the metal flow and directly extruding multiple curved materials at one time. The curved materials are not subject to lateral torque, thereby preventing cross-sectional deformation of the curved materials. The utility model patent with patent number CN200920221504.0 and publication date June 16, 2010 discloses an eccentric extrusion molding device for pipe bending parts. This method adopts an eccentric structure design between the punch of the molding part of the mold and the discharge port, and extrudes and prepares pipe bending parts by controlling the eccentric distance. The wall thickness of the pipe bending parts is uniform and wrinkle-free, and the cross-section is not distorted.

[0005] At present, the extrusion process for component forming and manufacturing has become increasingly mature. In order to achieve coordinated control of shape and short process integration and expand its scope of application, the development of new extrusion forming technologies with high efficiency and low consumption that can meet the diverse needs of structure and function and have high adaptability to actual production has become an important development direction pursued in this field. Summary of the invention

[0006] In order to solve the problems of poor quality of formed parts, high cost and low production efficiency caused by the two-step method of forming first and then bending in the traditional arc-shaped material forming and manufacturing, and realize the quantitative control of the dimensional accuracy and curvature radius of the arc-shaped material, the present invention provides a multi-inclined hole die arc-shaped material extrusion forming device and method, which is particularly suitable for the forming and manufacturing of low-plasticity and difficult-to-deform metal arc-shaped materials, that is, a plurality of discretely distributed die holes are prefabricated on the die plate according to certain distribution characteristics, so that the concentrated force originally concentrated in the local area of ​​the die plate is effectively dispersed, and the service life of the mold is significantly improved; the prefabricated holes can be arranged in a linear, regular array or complex special-shaped characteristic form, and the axis of the prefabricated holes and the extrusion axis form a certain angle, and at the same time, the stress state and flow behavior distribution of the extruded material at the die mouth can be adjusted in combination with the adjustment of the die plate thickness, so as to realize the quantitative control of the microstructure, curvature radius and change characteristics of the extruded arc-shaped material; according to actual needs, the key process parameters such as the number of prefabricated holes, distribution characteristics, inlet and outlet layout extrusion ratio and axis angle can be flexibly set, and multiple high-performance arc-shaped material products with curvature characteristics can be directly extruded at one time.

[0007] The present invention is achieved through the following technical solutions: Device: The multi-inclined hole die arc material extrusion forming device comprises: a punch 1, an extrusion cylinder 2, a blank 3, a die plate 4, and a base 5.

[0008] Method: The method is achieved by the following steps: Step 1, prepare metal material and process it into a cylindrical blank 3 with a diameter of D and a height of h; Step 2: Place the cylindrical blank into a heating furnace and perform homogenization treatment at a temperature of T1 for a holding time of t1; Step 3: Place the extrusion cylinder 2 on the base 5, immerse the die plate 4, the blank 3, and the punch 1 into the water-based graphite respectively, and then put them into the extrusion cylinder 2 in sequence; Step 4: Place the entire device assembly into a heating furnace and heat it to a predetermined temperature T2, and keep it at a predetermined temperature for a specific time t2, take out the entire device assembly, and then place it on a press machine workbench; Step 5: The hydraulic press is activated. Under the pressure of the hydraulic press, the punch 1 starts to move downward by a distance of H. The blank 3 is subjected to three-dimensional compressive stress and shear stress, undergoes plastic deformation and starts to flow until it flows out through each outlet. Step 6: After extrusion, the hydraulic press is adjusted to return and the base 5 in the device assembly is removed, and the device assembly without the base 5 is placed on the workbench of the press again; Step 7: Move the hydraulic press to punch the formed part and the die plate 4 out of the extrusion cylinder 2 from top to bottom through the punch 1; Step 8: quickly remove the mold plate 4 from the formed part, and put the formed part into water for quenching treatment to ensure the accuracy of the microstructure.

[0009] The present invention adopts the above technical solution, so it has the following beneficial effects: 1. The present invention exhibits unique novelty in tooling design, which is reflected in the ingenious design concept of the die plate structure. That is, a number of discretely distributed die holes are prefabricated on the die plate according to certain distribution characteristics. The prefabricated holes can be arranged in a linear, regular array or complex special-shaped geometric form, and the axis of the prefabricated hole forms a certain angle with the extrusion axis. When the punch is loaded downward, a number of high-performance curved products with different curvature characteristics can be extruded at one time. Second, according to the actual needs and comprehensive factors such as the life of the mold, the key process parameters such as the number of prefabricated holes, distribution characteristics, inlet and outlet cross-sectional area ratio and axis angle can be flexibly set, so the design has a higher degree of freedom. At the same time, the thickness of the die plate can be adjusted to adjust the stress state of the extruded material at the die mouth and the distribution of the flow behavior, so as to achieve quantitative control of the curvature radius and change characteristics of the extruded arc material, and meet the diverse needs of personalization and customization; 3. Compared with the traditional two-step method of forming first and then bending, the present invention effectively connects and integrates the two previous independent processes, avoiding the probability of defects such as surface cracks, springback and cross-sectional distortion caused by factors such as residual stress, greatly shortening the process flow, significantly improving production efficiency, reducing production costs, and significantly improving the surface quality and shape and size accuracy of the formed products, so that the batch forming and manufacturing of arc-shaped products can be integrated into a short process; 4. During the extrusion forming process, the blank first flows into the die plate to produce shear deformation, which causes the initial refinement of the structure. Subsequently, since the axis of the prefabricated hole and the extrusion axis are at a certain angle, the process of the material flowing through the prefabricated hole is equivalent to equal channel angular extrusion, and then it is extruded and formed. Therefore, the accumulated shear deformation is significantly increased, which is more conducive to the deep refinement of the microstructure of the extruded arc material, and the microstructure structure can be quantitatively controlled by the axis inclination angle of the die hole and the local extrusion ratio, and the mechanical properties of the formed arc material can be optimized; 5. According to the cross-sectional shape and geometric features of the required arc-shaped products, several prefabricated holes with corresponding cross-sectional geometric features can be set on the die plate. The cross-sectional shape can be round, square or complex and special-shaped. At the same time, hollow materials can also be formed and manufactured to achieve the purpose of "one mold for multiple shapes" to form and manufacture a variety of complex cross-sectional arc materials at one time, without stopping to replace equipment or adding additional auxiliary processes, reducing the time and cost loss caused by frequent mold changes, and significantly improving production efficiency; Sixth, the present invention can design several prefabricated holes on the die plate into a variable cross-section channel structure according to actual needs, that is, the cross-sectional area of ​​the inlet and outlet of the prefabricated hole is different, which is equivalent to a variable cross-section angular extrusion method, and can realize a combination of multiple local deformation modes at different prefabricated holes in a one-time extrusion forming process. As the material flows through the variable cross-section channel, extrusion and shear deformation occur, and the microstructure morphology of the extruded product can be deeply refined through the local deformation ratio; 7. The present invention simultaneously arranges a plurality of prefabricated die holes which are discretely distributed according to a certain rule on the die plate, so that the concentrated force originally concentrated in a local area on the die plate is effectively dispersed, which significantly reduces the risk of damage and cracking of the die due to excessive stress concentration, and significantly reduces the total extrusion ratio, making it easier for the metal to be extruded and formed, and significantly improves the service life of the die; 8. When extruding low-plasticity and hard-to-deform materials, it is often necessary to reduce the extrusion ratio or increase the forming temperature to improve the extrusion forming performance, which is bound to bring certain challenges to the formulation of process plans and the implementation of actual production. The "one die with multiple holes" design concept of the present invention increases the extrusion die area, effectively reduces the overall extrusion ratio, and significantly improves the extrusion forming ability. In addition to conventional metal materials, it is also suitable for batch forming and manufacturing of arc-shaped materials with low plasticity and hard to deform. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a main cross-sectional view of the two-dimensional plane structure of the device of the present invention; Figure 2-1 It is a main cross-sectional view of the two-dimensional plane structure of the prefabricated hole mold plate distributed in a straight line in the present invention; Figure 2-2 It is a three-dimensional schematic diagram of the prefabricated hole mold plate distributed in a straight line in the present invention; Figure 3-1 It is a main cross-sectional view of the two-dimensional plane structure of the mold plate with prefabricated holes distributed in a circumference in the present invention; Figure 3-2 It is a three-dimensional schematic diagram of a mold plate with prefabricated holes distributed in a circumference in the present invention; Figure 4-1 It is a main cross-sectional view of a two-dimensional plane structure of a prefabricated hole mold plate with different cross-sectional shapes and distributed in a straight line in the present invention; Figure 4-2 It is a three-dimensional schematic diagram of a prefabricated hole mold plate with different cross-sectional shapes and distributed in a straight line in the present invention; Figure 5-1 It is a main cross-sectional view of a two-dimensional plane structure of a mold plate with prefabricated holes having different cross-sectional shapes and distributed circumferentially in the present invention; Figure 5-2 It is a three-dimensional schematic diagram of a mold plate with prefabricated holes having different cross-sectional shapes and distributed in a circumference in the present invention; Figure 6-1 It is a main cross-sectional view of a two-dimensional plane structure of a mold plate with variable cross-section channels and prefabricated holes distributed in a straight line in the present invention; Figure 6-2 It is a three-dimensional schematic diagram of a mold plate with variable cross-section channels and prefabricated holes distributed in a straight line in the present invention; Figure 7-1 It is a main cross-sectional view of a two-dimensional plane structure of a mold plate having a variable cross-section channel and prefabricated holes distributed in a circumference in the present invention; Figure 7-2 It is a three-dimensional schematic diagram of a mold plate with variable cross-section channels and circumferentially distributed prefabricated holes in the present invention. DETAILED DESCRIPTION

[0011] The design scheme of the present invention is described in detail below with reference to the accompanying drawings, which are only used to help understanding and cannot represent all the ideas of the invention.

[0012] Specific implementation method 1: Combination Figure 2-2 The present implementation method is described. The present implementation method includes a punch 1, an extrusion barrel 2, a blank 3, a die plate 4, and a base 5. The present implementation method is completed by the following steps: 1. Processing a metal blank 3 with a diameter of D and a height of h; 2. Putting the blank 3 into a heating furnace for homogenization treatment, heating it to T1 and keeping it warm for a period of time t1; 3. Cleaning impurities in the extrusion barrel 2; 4. Placing the extrusion barrel 2 above the base 5, lubricating the die plate 4, the blank 3, and the punch 1 with discharge ports distributed on the same straight line and with different inclination angles α with water-based graphite, and then placing them into the extrusion barrel 2 in sequence; 5. The assembly is placed in a heating furnace and heated to a predetermined temperature T2, and kept warm for a specific time t2, and the assembly is taken out and then placed on the workbench of the press; Sixth, the hydraulic press is mobilized, and the punch 1 starts to move under the pressure of the hydraulic press, and moves downward a distance of H, and the blank 3 is plastically deformed under pressure and begins to flow until it flows out through each outlet; Seventh, after extrusion, the hydraulic press is mobilized to return and the base 5 is removed, and the assembly is placed on the workbench of the press again after the base 5 is removed; Eighth, the hydraulic press is mobilized, and the formed part and the die plate 4 are punched out of the extrusion cylinder 2 from top to bottom through the punch 1. Ninth, the die plate 4 on the formed part is quickly removed, and the formed part is placed in water for quenching to ensure the accuracy of the microstructure.

[0013] Specific implementation method 2: The distribution pattern of the prefabricated holes on the mold plate 4 is different, and multiple prefabricated holes are distributed in a circle. The distribution patterns of different prefabricated holes on the specific mold plate are as follows: Figure 3-2 , 5-2 , as shown in 7-2, the specific operation is the same as that of the first specific implementation method.

[0014] Specific implementation method three: According to the different requirements for the cross-sectional shape and geometric characteristics of the arc profile, the cross-sectional shape and geometric characteristics of the prefabricated holes of the die plate are adjusted. The different prefabricated hole patterns of the specific die plate are as follows: Figure 4-2 As shown, the prefabricated hole shapes designed according to the requirements of the arc profile include but are not limited to circular, rectangular, I-shaped, etc. Different prefabricated hole shapes can be combined arbitrarily, and the specific operation is the same as the specific implementation method one.

[0015] Specific implementation method 4: The prefabricated hole on the mold plate 4 is a variable cross-section channel. The specific variable cross-section channel diagram of the mold plate is as follows: Figure 6-2 As shown, the specific operation is the same as that of the first specific implementation mode.

Claims

1. A device and method for extruding arc-shaped materials with multiple inclined hole dies, the specific steps of the method are as follows: step 1, prepare metal materials and process them into cylindrical blanks 3 with a diameter of D and a height of h; step 2, place the cylindrical blanks in a heating furnace and homogenize them at a temperature of T1, and keep them warm for a time of t1; step 3, clean the impurities in the extrusion barrel 2; step 4, place the extrusion barrel 2 on the base 5, immerse the die plate 4, the blank 3, and the punch 1 in water-based graphite respectively, and then place them in the extrusion barrel 2 in sequence; step 5, place the device assembly as a whole in a heating furnace, heat it to a predetermined temperature T2, and keep it warm for a specific time t2, take out the device assembly as a whole, and then It is placed on the workbench of the hydraulic press; step six, mobilize the hydraulic press, and the punch 1 starts to move downward under the pressure of the hydraulic press, the moving distance is H, the blank 3 is subjected to three-way compressive stress and shear stress, undergoes plastic deformation and begins to flow, until it flows out through each discharge port; step seven, after extrusion, mobilize the hydraulic press to return and remove the base 5 in the device assembly as a whole, and place the device assembly as a whole after removing the base 5 on the hydraulic press workbench again; step eight, mobilize the hydraulic press, and punch the formed part and the die plate 4 out of the extrusion cylinder 2 from top to bottom through the punch 1; step nine, quickly remove the die plate 4 on the formed part, and put the formed part into water for quenching treatment to ensure the accuracy of the microstructure.

2. The multi-inclined hole die arc-shaped material extrusion forming device and method according to claim 1, characterized in that: By effectively connecting and integrating the two previous independent processes, the probability of cracks, springback and cross-sectional distortion defects caused by factors such as residual stress is avoided, the process flow is greatly shortened, the production cost is reduced, and the surface quality and shape and size accuracy of the formed products are significantly improved, so that the batch forming manufacturing of arc-shaped products can be realized in a short process integration.

3. The multi-inclined hole die arc-shaped material extrusion forming device and method according to claim 1, characterized in that: A number of discretely distributed die holes are prefabricated on the die plate according to a certain distribution rule, and the axes of different prefabricated holes form certain angles α1, α2, α3...α with the extrusion axis. n , where α1≠α2≠α3≠…≠α n , so that when the punch moves downward, multiple high-performance arc-shaped products with curvature characteristics can be extruded simultaneously at one time.

4. The multi-inclined hole die arc-shaped material extrusion forming device and method according to claim 1, characterized in that: According to actual needs and comprehensive factors such as mold life, key process parameters such as the number a of prefabricated holes and the axis inclination angle α can be flexibly set, and must satisfy a≥2, 0°<α<90° to affect the stress state and flow behavior distribution of the extruded material at the die mouth, thereby dispersing the local force on the die plate and further increasing the cumulative shear deformation of the billet, thereby achieving quantitative control of the microstructure, curvature radius and change characteristics of the extruded arc material.

5. The multi-inclined hole die arc-shaped material extrusion forming device and method according to claim 1, characterized in that: According to the cross-sectional shape and geometric features of the required arc-shaped materials, several prefabricated holes with different geometric characteristic cross-sections can be set on the mold plate at the same time. The cross-sectional shape can be round, square, complex and special-shaped, etc., so as to form and manufacture solid materials or hollow materials, etc., so as to achieve the purpose of "one mold for multiple shapes" and form and manufacture a variety of complex cross-sectional arc-shaped materials at one time, without stopping to replace equipment or adding additional auxiliary processes, reducing the time and cost loss caused by frequent mold changes.

6. The multi-inclined hole die arc-shaped material extrusion forming device and method according to claim 1, characterized in that: The preformed holes on the die plate can be designed as variable cross-section channels according to actual needs. The upper and lower cross-sectional areas of the preformed holes are S1 and S2, respectively, where S1>S2. When the billet flows through the variable cross-section channel, extrusion and shear deformation occur, which is equivalent to the variable cross-section angular extrusion method. It can realize the combination of multiple local deformation modes at different preformed holes in a single extrusion forming process. The microstructure morphology of the extruded product can be deeply refined through the local deformation ratio.

7. The multi-inclined hole die arc-shaped material extrusion forming device and method according to claim 1, characterized in that: The "one mold, multiple holes" design concept increases the outlet area, effectively reduces the deformation ratio, and greatly improves the uniformity of extrusion flow, providing a more efficient and feasible solution for batch forming of arc-shaped materials with low plasticity, difficult deformation and curvature characteristics.

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