Extrusion casting and tailor-welded integrated forming method and die

Abstract

The present disclosure relates to the field of casting technology, and provides an extrusion casting and welding integrated molding method and mold. The extrusion casting and welding integrated molding method includes: determining the welding joint area of ​​the part to be cast, and making a transition part; placing the transition part in the mold, and dividing the mold cavity into multiple sub-cavities through the transition part; filling the multiple sub-cavities with molten metal and filling them into sub-parts, and melting and joining the sub-parts with the outer surface of the transition part to form a weld seam; demolding the parts, and performing reinforcement welding along the weld seam. The extrusion casting and welding integrated molding method provided by the present disclosure can avoid the metal liquid flow being too long by filling liquid into multiple sub-cavities at the same time, and can form a regular weld seam between the sub-parts and the transition part, thereby avoiding the disordered joining of the metal liquid flow front, and at the same time, the weld seam can also increase the bonding strength and plasticity through welding.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of casting, in particular to an extrusion casting and tailor-welding integrated forming method and die. BACKGROUND

[0002] At present, the wide application of aluminum alloy parts on the vehicle body shows great potential and broad prospects, especially in recent years, the casting forming technology of integrated large thin-walled vehicle body parts is applied more and more widely, among which, air trapping and shrinkage cavity defects are prone to occur during high-pressure casting, the yield is low, heat treatment cannot be realized, the overall mechanical properties are low, and the yield is not high; the parts formed by extrusion casting have fine organization and can be heat treated, and the mechanical properties are better, which has been applied in the production of small-sized thick-walled parts, however, in the manufacturing field of large integrated thin-walled parts, this process still faces challenges.

[0003] Such parts often have complex spatial modeling structures, which increases the flow resistance of the metal liquid during the forming process, making it difficult to achieve full filling; at the same time, due to the thin wall thickness of the parts, the heat exchange between the metal liquid and the mold is extremely violent, which easily causes the problem of too fast solidification speed, causing cold shut phenomenon, even if there are some methods of opening multiple gates for pouring, but the metal liquid flow front is prone to disorderly jointing problem, which is difficult to reinforce and joint in the later period. SUMMARY

[0004] In order to solve the above technical problems or at least partially solve the above technical problems, the present disclosure provides an extrusion casting and tailor-welding integrated forming method and die.

[0005] The first aspect of the present disclosure provides an extrusion casting and tailor-welding integrated forming method, comprising the following steps:

[0006] S1, determining a tailor-welding jointing area of a part to be cast, and making a transition part according to the shape of the part to be cast corresponding to the tailor-welding jointing area;

[0007] S2, placing the transition part in the mold, and dividing the cavity of the mold into multiple sub-cavities through the transition part;

[0008] S3, filling metal liquid into multiple sub-cavities and forming multiple sub-parts, and melting jointing between the sub-parts and the outer surface of the transition part to form a weld joint;

[0009] S4, demolding the sub-parts and the transition part, and welding along the weld joint.

[0010] Optionally, between the step S2 and the step S3, it further comprises:

[0011] preheating the mold as a whole;

[0012] locally heating the area of the mold corresponding to the transition part, and / or applying current to the transition part to heat the transition part to a semi-solid state and maintain the temperature.

[0013] Optionally, the step S3 specifically comprises:

[0014] S31, filling the metal liquid into the end of the sub-cavity away from the transition part until the metal liquid fills the entire sub-cavity in the direction towards the transition part.

[0015] Optionally, the step S31 specifically comprises:

[0016] Setting the piston of the squeeze casting equipment to fill the metal liquid into the plurality of sub-cavities at a preset speed, wherein the preset speed of the piston is between 0.05 m / s and 4.0 m / s.

[0017] Optionally, the step S31 further comprises:

[0018] S32, increasing the pressure of the piston of the squeeze casting equipment to a preset pressure and performing pressure holding and shrinkage before the metal liquid solidifies, wherein the preset pressure of the piston is between 80 MPa and 300 MPa.

[0019] Optionally, the step S3 specifically comprises:

[0020] Filling the mold with aluminum alloy metal liquid to form the sub-part.

[0021] Optionally, the step S1 specifically comprises:

[0022] S11, determining the tailor-welded joint area;

[0023] S12, determining the shape of the transition part according to the tailor-welded joint area;

[0024] S13, filling the mold with metal liquid having a higher strength than the sub-part after filling to form the transition part according to the determined shape.

[0025] A second aspect of the present disclosure provides a mold for processing the part to be cast according to the squeeze casting and tailor-welding integrated forming method of any one of the above;

[0026] The mold comprises an upper mold, a lower mold, and a plurality of squeeze slides, the plurality of squeeze slides are arranged on the lower mold and jointly form the cavity, the upper mold is provided with a plurality of gating systems, and the plurality of gating systems are in one-to-one correspondence with the plurality of sub-cavities.

[0027] Optionally, the upper die and the lower die are provided with heating devices at regions corresponding to the transition part.

[0028] Optionally, the gating system is arranged at an end of the corresponding sub-cavity away from the transition part.

[0029] Compared with the prior art, the technical scheme provided by the embodiments of the present disclosure has the following advantages:

[0030] The extrusion casting and tailor-welding integrated forming method provided by the present disclosure comprises the following steps: determining a tailor-welding joint area of a cast part, and manufacturing a transition part according to the shape of the cast part corresponding to the tailor-welding joint area; placing the transition part in a mold, and dividing a cavity of the mold into multiple sub-cavities through the transition part; filling the multiple sub-cavities with a molten metal and forming multiple sub-parts, and the sub-parts and the outer surface of the transition part are fusedly joined to form a weld joint; demolding the sub-parts and the transition part, and welding along the weld joint. By arranging the transition part in the mold, the cavity of the mold can be divided into multiple sub-cavities, and by simultaneously filling the multiple sub-cavities with the molten metal, the flow of the molten metal can be prevented from being too long, and defects such as cold shut and underfilling can be avoided, the metal liquid filling capacity of the complex thin-walled part is improved, the casting performance is improved, and the extrusion casting of the large-size or super-large-size integrated thin-walled part is facilitated. At the same time, a regular weld joint can be formed between the sub-parts and the transition part, the front of the molten metal flow is prevented from being disorderly joined, and the problem that the molten metal flow is difficult to be reinforcedly joined in the later stage is avoided. For the weld joint produced by casting, the aluminum alloy grains can be refined, the weld joint strength and plasticity can be increased, the reliability and consistency of the welded part can be ensured, and the overall mechanical properties of the part can be improved. BRIEF DESCRIPTION OF DRAWINGS

[0031] The accompanying drawings, which are incorporated into and form a part of the specification, illustrate one embodiment consistent with the present disclosure and, together with the description, serve to explain the principles of the disclosure.

[0032] In order to more clearly illustrate the technical scheme in the embodiments of the present disclosure or the prior art, the accompanying drawings needed to be used in the embodiments or the prior art description will be briefly introduced. Obviously, for those skilled in the art, other drawings can also be obtained from these drawings without creative labor.

[0033] Figure 1 A step diagram of the extrusion casting and tailor-welding integrated forming method of an embodiment of the present disclosure;

[0034] Figure 2 A structural schematic diagram of a mold of an embodiment of the present disclosure;

[0035] Figure 3 A flow schematic diagram of a molten metal of an embodiment of the present disclosure;

[0036] Figure 4 The installation schematic diagram of the extrusion slide of an embodiment of the present application;

[0037] Figure 5 The exploded view of the mold of an embodiment of the present application;

[0038] Figure 6 The structural schematic diagram of the sub-pieces and the transition piece after demolding of an embodiment of the present application;

[0039] Figure 7 The welding schematic diagram of the welding joint of an embodiment of the present application.

[0040] In the figure: 1, the piece to be cast; 11, the transition piece; 12, the sub-piece; 13, the welding joint; 14, the welding seam; 15, the pouring surplus block; 2, the mold; 21, the sub-cavity; 22, the upper mold; 23, the lower mold; 24, the extrusion slide; 25, the pouring system; 251, the barrel; 252, the pouring channel. DETAILED DESCRIPTION

[0041] In order to enable a more clear understanding of the above-mentioned objects, features and advantages of the present disclosure, the schemes of the present disclosure will be further described below. It should be noted that the embodiments of the present disclosure and the features in the embodiments can be combined with each other without conflict.

[0042] In the following description, a lot of specific details are set forth in order to give a thorough understanding of the present disclosure, but the present disclosure can also be implemented in other manners different from those described herein; obviously, the embodiments in the description are only some embodiments of the present disclosure, rather than all the embodiments.

[0043] The extrusion casting and tailor-welding integrated forming method and the mold will be described in detail below through specific embodiments:

[0044] Referring to Figures 1 to 7 Some embodiments of the present application provide an extrusion casting and tailor-welding integrated forming method, which comprises the following steps: S1, determining the tailor-welding joint area of the piece to be cast 1, and manufacturing the transition piece 11 according to the shape of the piece to be cast 1 corresponding to the tailor-welding joint area; S2, placing the transition piece 11 in the mold 2, and dividing the cavity of the mold 2 into multiple sub-cavities 21 through the transition piece 11; S3, filling the metal liquid into the multiple sub-cavities 21 through the pouring system 25 and forming multiple sub-pieces 12, and the sub-pieces 12 and the outer surface of the transition piece 11 are melt-joined to form the welding joint 13; S4, demolding the sub-pieces 12 and the transition piece 11, and welding along the welding joint 13.

[0045] In a specific implementation, the transition part 11 is arranged in the mold 2 to divide the cavity of the mold 2 into multiple sub-cavities 21, and the metal liquid can be filled into the multiple sub-cavities 21 at the same time, so that the metal liquid flow is not too long, and defects such as cold shut and insufficient pouring are avoided, the metal liquid filling capacity of the complex thin-walled part is improved, the casting performance is improved, which is helpful for extrusion casting of large or super-large integrated thin-walled parts; at the same time, a regular welding seam 13 can be formed between the sub-part 12 and the transition part 11, so as to avoid the problem that the metal liquid flow front is difficult to be reinforced and joined in the later stage due to disordered joining. For the welding seam 13 generated during casting, the aluminum alloy grains can be further refined by reinforcing welding, the welding seam 13 joint strength and plasticity are increased, the reliability and consistency of the welding position are ensured, and the overall mechanical properties of the part are improved.

[0046] It can be understood that the transition part 11 is directly formed as part of the cast part after casting, and since the transition part 11 and the pouring metal liquid are different in material, hardness or other aspects, when the metal liquid flows to the surface of the transition part 11, the sub-part 12 with a surface closely joined with the transition part 11 can be formed, but the strength of the welding position between the transition part 11 and the sub-part 12 can be lower than that of the integrally poured part, and the large-scale body part can be obtained by welding and reinforcing with the adjacent sub-part 12. The welding method can be friction stir welding to form a weld 14 with high connection strength at the welding seam 13 position to ensure the structural strength.

[0047] That is, the present disclosure divides a large overall cavity into multiple sub-cavities 21 with smaller volumes, so that the aluminum alloy metal liquid can easily fill the sub-cavities 21, eliminating the defects of the traditional method of filling from one end with a single cavity and a long flow path. The sub-cavities 21 have small internal volumes, the metal liquid flows easily, the resistance is small, and solidification and cold shut are not easy to occur; and the metal liquid flow is short in each sub-cavity 21, and the pressure is easily transmitted to the inside of the sub-cavity 21 during pressure compensation, thereby eliminating shrinkage and porosity defects, making the structure more fine, and the part strength higher. Secondly, by pre-setting the transition part 11, the metal liquid does not produce turbulent flow to cause complex joint tracks, so that the welding seam 13 shape is very regular, and the friction stir welding can be used to strengthen the welding seam 13.

[0048] Reference Figure 2 and Figure 3As shown, between step S2 and step S3, there is also: overall preheating the mold 2, locally heating the area of the mold 2 corresponding to the transition part 11, and / or, electrically heating the transition part 11 to heat the transition part 11 to a semi-solid state and keep warm, and the solid phase rate of the transition part 11 in the semi-solid state is greater than or equal to 40%. It can be understood that the semi-solid transition part 11 is beneficial to fusion welding between the adjacent sub-parts 12, thereby being able to improve the bonding strength and ensure the integration performance of the cast part.

[0049] Specifically, by applying high voltage to the transition part 11 to heat by its own resistance, or by locally heating the transition part 11 through the heating device on the mold 2, subsequent welding and bonding are facilitated.

[0050] In some embodiments, step S3 specifically includes: S31, filling the metal liquid at the end of the sub-cavity 21 away from the transition part 11 until the metal liquid fills the entire sub-cavity 21 in the direction towards the transition part 11.

[0051] Referring to Figure 3 As shown, after the metal liquid enters the inside of the sub-cavity 21 through the gating system 25, it flows in the direction towards the transition part 11 from the end away from the transition part 11, that is, the metal liquid flows in the direction of the arrow in the middle of the figure. Figure 3 The metal liquid in each sub-cavity 21 flows in the direction of the arrow in the middle of the figure towards the transition part 11 until it fills the entire sub-cavity 21, the filling process of the metal liquid in each sub-cavity 21 is short, the filling capacity is high, and the forming effect is good.

[0052] Specifically, step S31 specifically includes: setting the piston of the squeeze casting equipment to fill the metal liquid into the plurality of sub-cavities 21 at a preset speed, it can be understood that the piston can move at a constant speed to extrude the metal liquid, thereby ensuring that the metal liquid is completely pressed into the cavity of the mold 2. The preset speed of the piston is between 0.05 m / s and 4.0 m / s.

[0053] It can be understood that the squeeze casting and tailor-welded integrated forming method of the present disclosure is suitable for large thin-walled body parts. According to relevant textbooks and technical manuals, the filling speed (i.e. the speed of the piston extruding the metal liquid) during direct squeeze casting is generally selected to be between 0.05 m / s and 0.1 m / s, and the filling speed during indirect squeeze casting is generally selected to be between 0.5 m / s and 1.5 m / s, that is, the preset speed of the piston should be at least greater than or equal to 0.05 m / s, so as to ensure that the metal liquid fills smoothly.

[0054] Of course, when the piston moves to fill the metal liquid, the greater the wall thickness, the smaller the filling speed should be, the smaller the wall thickness, the greater the filling speed should be, the smaller the part, the smaller the filling speed should be, the larger the part, the greater the filling speed should be, for large thin-walled parts, the preset speed of the piston of the present disclosure should also be less than or equal to 4.0 m / s. In this way, the movement speed of the piston will not be too large, which can ensure that the metal liquid is filled while avoiding wasting the power driving the piston movement, thereby improving the filling efficiency and ensuring the filling effect.

[0055] Further, step S31 also includes: S32, before the metal liquid solidifies, the pressure of the piston of the extrusion casting device is increased to a preset pressure and pressure holding compaction is performed to perform solidification compaction treatment, which can eliminate shrinkage and porosity defects, increase the density of the part, and until the metal solidifies, it also helps to form a tightly bonded weld seam 13 between the metal liquid and the transition part 11. Wherein, the preset pressure of the piston is between 80Mpa and 300MPa.

[0056] According to the alloy type and the liquid forging coefficient, for the aluminum alloy extrusion casting process, the preset pressure P of the piston = k1*k2, wherein k1 = 80-100MPa, the direct extrusion casting coefficient k2 = 1-1.5, and the corresponding preset pressure is between 80MPa and 150MPa; the indirect extrusion casting coefficient k2 = 1.5-2, and the corresponding preset pressure is between 150MPa and 200MPa, that is, the preset pressure of the piston should be at least greater than or equal to 80MPa, which can ensure that the metal liquid fills smoothly.

[0057] Of course, for large thin-walled parts, the preset pressure of the piston of the present disclosure should also be less than or equal to 300MPa to complete the extrusion casting of large or super-large parts, which can adapt to more advanced equipment and ensure the filling efficiency of the metal liquid.

[0058] Of course, it should be pointed out that the transition part 11 will be able to divide the cavity into a plurality of sub-cavities 21, and the sub-cavities 21 have a shorter compaction flow, which is beneficial to pressure holding compaction and can improve the casting performance.

[0059] In some embodiments, between step S1 and step S2, the surface of the transition part 11 is cleaned to ensure that there is no oxide skin and oil stains and other impurities. In this way, the bonding performance between the transition part 11 and the sub-part 12 after pouring can be ensured.

[0060] In some embodiments, the step S3 specifically includes: filling with aluminum alloy metal liquid to form a sub-part 12, so that the aluminum alloy metal liquid can be filled sufficiently to ensure the product effect after filling.

[0061] Further, the step S1 specifically comprises: S11, determining a tailor-welding joint area; S12, determining the shape of the transition part 11 according to the tailor-welding joint area; and S13, forming the transition part 11 by using a molten metal with a strength higher than that of the sub-part 12 after filling to form a shape according to the determined shape.

[0062] That is, the present disclosure can obtain a transition part 11 with higher structural strength by changing the material of the transition part 11, specifically, a deformed aluminum alloy molten metal with a strength higher than that of a cast aluminum alloy, by arranging the transition part 11 at a specific position, the final obtained cast part can have structural and strength differences in spatial distribution, and further can impart different mechanical properties to different areas of the cast part, to meet the diversified design requirements, that is, the final formed cast part has certain strength gradient differences in spatial distribution, and further meets the strength customization demand.

[0063] In specific implementation, the tailor-welding joint area can be determined by CAE simulation analysis or based on design requirements, and the transition part 11 is designed according to the welding joint area.

[0064] Of course, the transition part 11 can also increase the structural strength in other ways, which is not limited in the present disclosure, and can be specifically set according to actual needs.

[0065] Specifically, the tailor-welding joint area in step S11 can be the flow convergence state and position of the multi-cavity molten metal in the mold 2, or can be different local areas based on the strength requirements of the cast part structure design space. Further, the transition part 11 is fixedly arranged on the lower mold 23 to prevent displacement during pouring, and further to ensure that the position of the transition part 11 can completely correspond to the tailor-welding joint area on the cast part, and further to ensure the structural performance of the cast part.

[0066] Some other embodiments of the present disclosure provide a mold 2 for processing a cast part 1 according to the extrusion casting and tailor-welding integrated molding method of any of the above embodiments.

[0067] Specifically, referring to Figure 4 and Figure 5 , the mold 2 comprises an upper mold 22, a lower mold 23 and a plurality of extrusion slides 24, the plurality of extrusion slides 24 are arranged on the lower mold 23 and jointly form a cavity, the upper mold 22 is provided with a plurality of pouring systems 25, the plurality of pouring systems 25 are in one-to-one correspondence with the plurality of sub-cavities 21 and are in communication with the plurality of sub-cavities 21, so as to pour the sub-cavities 21 through the pouring systems 25.

[0068] In specific implementation, the lower mold 23 forms a containing groove for containing the extrusion slide 24, and the extrusion slide 24 can slide in the containing groove to extrude a cavity for casting, thereby realizing extrusion casting of the part.

[0069] In some embodiments, the area on the lower mold 23 corresponding to the transition part 11 is provided with a heating device, such as a resistance rod, a high-frequency magnetic induction device, etc., to locally heat the transition part 11 so that the transition part 11 can be in a semi-solid state.

[0070] Referring to Figure 2 and Figure 3 , the gating system 25 is arranged at the end of the corresponding sub-cavity 21 away from the transition part 11, and the gating system 25 includes a feeding cylinder 251 and a gating channel 252 connected to the feeding cylinder 251, the gating channel 252 being in communication with the cavity, and the feeding cylinder 251 being used for feeding, and the gating channel 252 being arranged at the side of the sub-cavity 21 away from the transition part 11 to complete the filling of the entire sub-cavity 21 by the flow of the metal liquid.

[0071] Exemplarily, referring to Figure 2 , the cavity of the mold 2 is internally provided with a transition part 11, and can be divided into two sub-cavities 21, and two gating systems 25 are correspondingly arranged, and the two gating systems 25 are arranged at the two sides of the transition part 11 and away from the transition part 11, so that multi-end feeding of the metal liquid can be realized to increase the filling efficiency.

[0072] After the gating is completed, referring to Figure 6 and Figure 7 , the metal liquid in the gating channel 252 and part of the feeding cylinder 251 forms a gating excess block 15, and after the sub-part 12 and the transition part 11 are demolded, the gating excess block 15 is removed by a cutting device, and then the weld joint 13 is reinforced and welded to complete the overall tailor-welding to form the final gating part.

[0073] It should be noted that, in this document, relational terms such as“first” and“second”, and the like, are used solely to distinguish one entity or action from another entity or action, without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms“comprises”,“comprising”, or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element preceded by“comprises a” does not, without more constraints, foreclose the existence of additional identical elements in the process, method, article, or apparatus that comprises the element.

[0074] The foregoing is merely illustrative of the various implementations of the present disclosure and the general principles thereof. Numerous modifications can be made to these illustrations, and equivalents can be substituted therefor, without departing from the scope of the present disclosure. The specific embodiments commensurate with the specific application are intended to be illustrative only and not limiting of the scope of the application as set forth in the following claims.

Claims

1. A method for integrated extrusion casting and tailor welding, characterized in that: The steps include: S1. Determine a butt-welded joint region of a part to be cast, and fill the mold with molten metal having a higher strength than that of the part to be cast after filling according to the shape of the part to be cast corresponding to the butt-welded joint region to produce a transition part; S2, placing the transition component in the mold, and dividing the mold cavity into a plurality of sub-cavities by the transition component; preheating the mold as a whole; locally heating the area of ​​the mold corresponding to the transition part, and / or applying electricity to the transition part to heat the transition part to a semi-solidified state and keep the temperature; S3, filling the plurality of sub-cavities with molten metal and forming a plurality of sub-parts, wherein the sub-parts are melted and joined to the outer surface of the transition part to form weld seams; S4, demoulding the sub-component and the transition component, and welding them along the weld seam; Wherein, the step S3 includes: S31, filling the molten metal into an end of the sub-mold cavity away from the transition part until the molten metal fills the entire sub-mold cavity in a direction toward the transition part.

2. The method for integrated extrusion casting and tailor welding according to claim 1, characterized in that: The step S31 specifically includes: The piston of the squeeze casting equipment is set to fill the molten metal into the plurality of sub-cavities at a preset speed, wherein the preset speed of the piston is between 0.05 m / s and 4.0 m / s.

3. The method of integrated extrusion casting and tailor welding according to claim 1, characterized in that: After step S31, the following steps are further included: S32. Before the molten metal solidifies, increase the pressure of the piston of the squeeze casting equipment to a preset pressure and perform pressure maintenance and shrinkage compensation, wherein the preset pressure of the piston is between 80 MPa and 300 MPa.

4. The method for integrated extrusion casting and tailor welding according to claim 1, characterized in that: The step S3 specifically includes: Aluminum alloy liquid metal is used to fill the mold to form the sub-component.

5. A mold, characterized in that: The mold (2) is used to process the part to be cast (1) according to the extrusion casting and tailor-welding integrated molding method according to any one of claims 1 to 4; The mold (2) comprises an upper mold (22), a lower mold (23) and a plurality of extrusion sliders (24), wherein the plurality of extrusion sliders (24) are arranged on the lower mold (23) and together form the mold cavity, and the upper mold (22) is provided with a plurality of pouring systems (25), and the plurality of pouring systems (25) are connected to the plurality of sub-cavities (21) in a one-to-one correspondence.

6. The mold according to claim 5, characterized in that Heating devices are provided on the upper mold (22) and the lower mold (23) in areas corresponding to the transition part (11).

7. The mold according to claim 5, characterized in that The pouring system (25) is arranged at an end of the corresponding sub-cavity (21) away from the transition part (11).

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