Manufacturing method of die-cast joint

Abstract

The present invention provides a method for manufacturing a die-cast joint using die-cast members as materials (joining members), capable of manufacturing a die-cast joint that can be bent significantly without breaking, and capable of manufacturing die-cast joints having various external and internal shapes. [Solution] A method for manufacturing a die-cast joint with excellent flexibility includes a joining member preparation step of preparing a first joining member (10) that is a die-cast member and has a first planned joining surface (12) and a second joining member (20) made of a metal material and having a second planned joining surface (22), and a die-cast joint formation step of forming a die-cast joint (1) by diffusion bonding the first joining member (10) and the second joining member (20) together by pressing them relative to each other so that pressure is applied to the first planned joining surface (12) and the second planned joining surface (22) under temperature conditions that allow the first joining member (10) and the second joining member (20) to form the die-cast joint (1).

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a die-cast joint. By law Regarding. [Background technology]

[0002] Conventionally, a method for manufacturing a bonded body formed by bonding metal members has been known that includes a step of preparing two metal members and a step of forming a bonded body by heating the two metal members while pressing them together (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5198458 Summary of the Invention [Problem to be solved by the invention]

[0004] One widely known metal forming method is die casting, which allows for the production of metal parts with high dimensional accuracy in a short time (high cycle time) by forcing molten metal into a mold.

[0005] Metal members manufactured by die casting (hereinafter referred to as die-cast members) are often used as products either as they are or after undergoing simple machining or processing, taking advantage of their high dimensional accuracy.

[0006] Die-cast components are relatively hard and brittle due to the molding method used, which means that they are generally unable to bend significantly without breaking, limiting post-processing options and making it difficult to broaden the range of uses for die-cast components.

[0007] Furthermore, because die casting is also a type of mold casting, there are limitations to the shapes of parts that can be manufactured. For example, with current technology, it is impossible to manufacture parts with external shapes that cannot be removed from the mold or parts with complex internal shapes (such as heat exchange medium flow paths) using die casting alone.

[0008] For this reason, it is believed that by applying the above-mentioned method of manufacturing a joined body by joining multiple metal members to die-cast members, it will be possible to manufacture joined bodies with a variety of external and internal shapes. In this specification, joined bodies at least partly derived from die-cast members (using die-cast members as materials) will be referred to as "die-cast joined bodies" to distinguish them from die-cast members.

[0009] However, joining die-cast components is not common. The main reason for this is that in the technical field of die-casting, in order to take advantage of the high dimensional accuracy, technological development has been carried out in the direction of manufacturing die-cast components with shapes similar to the final product.

[0010] The present invention has been made in view of the above-mentioned problems, and aims to provide a method for manufacturing a die-cast joint using die-cast members as the material (joint member) that can be bent significantly without breaking (i.e., has excellent flexibility) and that can produce die-cast joints with various external and internal shapes. Another aim is to provide a die-cast joint that, unlike die-cast members, can be bent significantly without breaking. [Means for solving the problem]

[0011] The method for manufacturing a die-cast joint of the present invention is a method for manufacturing a die-cast joint with excellent flexibility, and is characterized by including a joining member preparation process for preparing a first joining member which is a die-cast member and has a first planned joining surface, and a second joining member which is made of a metal material and has a second planned joining surface, and a die-cast joint formation process for forming the die-cast joint by diffusion bonding the first joining member and the second joining member by pressing the first joining member and the second joining member relative to each other so that pressure is applied to the first planned joining surface and the second planned joining surface under temperature conditions which allow the first joining member and the second joining member to be diffusion bonded.

[0012] The die-cast joint of the present invention is a die-cast joint having excellent flexibility, and is characterized by being produced by the method for producing a die-cast joint of the present invention.

[0013] The die-cast joint body of the present invention is a joint body derived from a first joining member, at least a portion of which is a die-cast member, and is characterized in that no chill layer derived from the first joining member is present at the joining interface between the first joining member and another member, and the Vickers hardness of the outer surface derived from the first joining member is 70% or less of the Vickers hardness of the first joining member before joining. [Effects of the Invention]

[0014] The method for manufacturing a die-cast joint of the present invention is a method for manufacturing a die-cast joint with excellent flexibility, and includes a die-cast joint formation step of forming a die-cast joint by diffusion-bonding the first and second bonding members by pressing the first and second bonding members relative to each other so that pressure is applied to the first and second intended bonding surfaces under temperature conditions that allow the first and second bonding members to be diffusion-bonded. Therefore, the method for manufacturing a die-cast joint of the present invention is a method for manufacturing a die-cast joint that uses die-cast members as materials (bonding members) and can bend significantly without fracture (i.e., has excellent flexibility), and can also be used to manufacture die-cast joints with a variety of external and internal shapes (see also the examples described below).

[0015] The die-cast joined body of the present invention is a die-cast joined body that can be bent significantly without breaking, unlike die-cast members before joining (see also the examples described later). [Brief explanation of the drawings]

[0016] [Figure 1] 3 is a flowchart of a method for manufacturing a die-cast joint body according to the first embodiment. [Figure 2] 10 is a diagram illustrating a joining member preparing step S10 in the first embodiment. FIG. [Figure 3] 1A and 1B are views for explaining a die-cast assembly forming step S20 in the first embodiment and a die-cast assembly 1 according to the first embodiment. [Figure 4] 1 is a cross-sectional view showing a state in which the die-cast joined body 1 according to the first embodiment is placed in a bent state on the surface of a temperature control target O. FIG. [Figure 5] 10A and 10B are views for explaining a joining member preparing step S10a in the second embodiment. [Figure 6] 10A and 10B are views for explaining a die-cast assembly forming step S20a in the second embodiment and a die-cast assembly 2 according to the second embodiment. [Figure 7]10 is a perspective view showing a state in which a die-cast joined body 2 according to a second embodiment is disposed inside a tubular member T. FIG. [Figure 8] 1A and 1B are diagrams illustrating a die-cast joined body 3 according to an embodiment and a die-cast member 4 for comparison. [Figure 9] FIG. 2 is a schematic diagram showing a three-point bending test in the examples. [Figure 10] FIG. 10 is a diagram showing the results of a bending test of a die-cast joint 3 according to an example. [Figure 11] FIG. 10 is a diagram showing the results of a bending test on a die-cast member 4 for comparison. [Figure 12] 10 is a diagram showing the results of observation of the vicinity of the interface in a die-cast joint body 3a according to the example. FIG. [Figure 13] FIG. 10 is a diagram showing the results of observation of the vicinity of the interface in a bolted die-cast member. DETAILED DESCRIPTION OF THE INVENTION

[0017] The manufacturing method of a die-cast assembly and the die-cast assembly of the present invention will be described below based on the embodiments shown in the drawings. The drawings are schematic diagrams and do not necessarily strictly reflect the actual structure, configuration, proportions, etc. The embodiments described below do not limit the invention according to the claims. Furthermore, not all of the elements and combinations thereof described in the embodiments are necessarily essential to the present invention.

[0018] [Embodiment 1] FIG. 1 is a flowchart of a method for manufacturing a die-cast joint body according to the first embodiment. 2A and 2B are diagrams illustrating the bonding member preparation step S10 in embodiment 1. FIG. 2A is a perspective view of a first bonding member 10, FIG. 2B is a plan view of the first bonding member 10, FIG. 2C is a cross-sectional view taken along the line A1-A1 in FIG. 2A, FIG. 2D is a perspective view of a second bonding member 20, FIG. 2E is a plan view of the second bonding member 20, and FIG. 2F is a cross-sectional view taken along the line A2-A2 in FIG. 2E. The x-, y-, and z-axes shown in FIG. 2 and other figures are intended to make it easier to understand the correspondence between the figures, and do not limit the orientation of components, etc., during the manufacturing method or use of the product.

[0019] 3A and 3B are diagrams illustrating the die-cast assembly forming step S20 in embodiment 1 and the die-cast assembly 1 according to embodiment 1. FIG. 3A is a cross-sectional view showing the first and second joining members 10 and 20 being pressed relative to each other, FIG. 3B is a cross-sectional view of the manufactured die-cast assembly 1, and FIG. 3C is a plan view of the manufactured die-cast assembly 1. FIGS. 3A and 3B are cross-sectional views corresponding to FIGS. 2C and 2F. The thick arrow indicated by the symbol P in FIG. 3A indicates that the first and second joining members 10 and 20 are being pressed relative to each other.

[0020] 3(a) shows how the first joining members 10 are fixed and a moving force is applied to the second joining members 20 (pressure is applied from the second joining members 20 side), but a base or jig for placing or fixing the first joining members 10 is not shown. The two-dot chain line in FIG. 3(b) indicates the joining interface P, but this does not indicate that the joining interface P remains as a structural feature in the die-cast joined body 1, but rather serves to clearly indicate that the die-cast joined body 1 is manufactured from two members. The two-dot chain line indicated by the symbol P is the same as in FIG. 3(b) in other figures described below.

[0021] Fig. 4 is a cross-sectional view showing the die-cast joined body 1 according to embodiment 1 placed in a bent state on the surface of a temperature control target O. Fig. 4 is a cross-sectional view corresponding to Fig. 3(b).

[0022] 1. Manufacturing method of die-cast joint First, a method for manufacturing a die-cast assembly according to embodiment 1 will be described. The method for manufacturing a die-cast assembly according to embodiment 1 is a method for manufacturing a die-cast assembly 1 having excellent flexibility, and includes a joining member preparation step S10 and a die-cast assembly formation step S20 (see FIG. 1). "A die-cast assembly having excellent flexibility" refers to "a die-cast assembly having higher flexibility than the die-cast member that is the material of the die-cast assembly." Each step will be described below.

[0023] The joining member preparation step S10 is a step of preparing a first joining member 10 and a second joining member 20 (see FIG. 2). The first joining member 10 and the second joining member 20 will be described below.

[0024] The first joining member 10 is a die-cast member. The first joining member 10 has a first planned joining surface 12, a plate-shaped portion 14, and a protruding portion 16 (see FIGS. 2(a) to 2(c)). An internal structure forming recess 18 is formed in the plate-shaped portion 14. Note that the inner surface of the internal structure forming recess 18 does not come into contact with a second planned joining surface 22 (described below) in the die-cast joint formation step S20, and is therefore not included in the first planned joining surface 12.

[0025] In this specification, "die-cast member" refers to a metal member manufactured by die-casting. The manufacturing method for the die-cast member may be a so-called normal die-casting method or a special die-casting method, but a method that produces a chill layer (described below) on the surface is used. In this specification, "die-cast member" also includes members that have undergone relatively minor post-processing (e.g., deburring or drilling).

[0026] The first intended joining surface 12 is preferably a casting surface. In this specification, the term "casting surface" refers to a surface that has not been subjected to mechanical treatment or processing (e.g., cutting or polishing) to change the surface shape after production by die casting. Even if a surface has been subjected to processing such as cleaning, the surface can be treated as a casting surface as long as the processing does not change the surface shape. Furthermore, the first intended joining surface 12 may be surface-processed to the extent that the chill layer (described below) is not removed. From this perspective, the first intended joining surface 12 may be a surface that has been processed (e.g., cut) to a thickness of 0.2 mm or less from the casting surface. Furthermore, the first intended joining surface 12 may be processed by shot blasting or the like.

[0027] The plate-shaped portion 14 is a portion having a flat plate shape. The first intended joining surface 12 of the first joining member 10 is at least a part of one main surface of the plate-shaped portion 14 (a surface that is not a side surface of the plate-shaped portion).

[0028] In the first joining member 10, the thickness D1 along the direction perpendicular to the first planned joining surface 12 in the portion where the first planned joining surface 12 exists is preferably within a range of 0.3 mm to 6 mm.

[0029] The main component of the material constituting the first joining member 10 is preferably aluminum, magnesium, or zinc. For example, a "material whose main component is aluminum" can also be expressed as "aluminum or an aluminum-based alloy." The same applies to metal elements other than aluminum. A specific example of a material whose main component is aluminum is an ADC-based material (e.g., ADC12), which is an alloy for die-casting.

[0030] The protruding portion 16 is a columnar portion that protrudes from the plate-like portion 14. The protruding portion 16 can be used for alignment during diffusion bonding by combining with a receiving hole 24 of the second bonding member 20. The protruding portion 16 may be formed or added by post-processing after molding by die-casting, but is preferably molded integrally with the plate-like portion 14 by die-casting.

[0031] The internal structure forming recess 18 is a groove-like structure formed to form the internal structure 18a of the die-cast joined body 1. The internal structure forming recess 18 may be formed by post-processing after molding by the die-casting method, or may be molded together with the plate-like portion 14 by the die-casting method.

[0032] The second joining member 20 is made of a metal material. The second joining member 20 has a second intended joining surface 22 (see FIGS. 2(d) to 2(f)). The second joining member 20 has a flat plate-like shape as a whole, and has a receiving hole 24 formed at a position corresponding to the protruding portion 16 of the first joining member 10.

[0033] In the second joining member 20, it is preferable that the thickness D2 along the direction perpendicular to the second planned joining surface 22 at the portion where the second planned joining surface 22 exists is 0.05 mm or more, and is less than the thickness along the direction perpendicular to the first planned joining surface 12 at the portion where the first planned joining surface 12 exists in the first joining member 10.

[0034] The main component of the metal material constituting the second joining member 20 is not particularly limited, but is preferably copper, nickel, aluminum, zinc, or magnesium. For example, a wrought material can be used as the second joining member 20. When the second joining member 20 is made of a wrought material, it is possible to obtain effects such as imparting various properties to the die-cast joined body 1 to be manufactured, supporting bending of the die-cast joined body 1, and suppressing the occurrence of defects (e.g., blisters) during joining.

[0035] It is also preferable that the second joint members 20 are die-cast members. When the second joint members 20 are die-cast members, the main component of the material constituting the second joint members 20 is preferably aluminum, magnesium, or zinc.

[0036] The die-cast joint formation process S20 is a process in which the first joining member 10 and the second joining member 20 are pressed relative to each other so that pressure is applied to the first planned joining surface 12 and the second planned joining surface 22 under temperature conditions that allow the first joining member 10 and the second joining member 20 to be diffusion bonded, thereby forming the die-cast joint 1 (see FIG. 3(a)). The die-cast joint formation process S20 includes a pressing process S22 and a cooling process S24.

[0037] In this specification, "pressing the first and second joining members relative to each other" does not necessarily mean pressing the first joining members by fixing the first joining members and applying a moving force to the second joining members (applying a pressing force from the second joining member side), as shown in Fig. 3(a). It also includes pressing the first joining members by fixing the second joining members and applying a moving force to the first joining members (applying a pressing force from the first joining member side), or pressing the first and second joining members by applying a moving force to both the first and second joining members (applying a pressing force from both the first and second joining member sides).

[0038] Furthermore, the moving force (pressing force) required for pressing may be generated by a mechanism that applies pressure from the outside (such as a hydraulic press mechanism), or may be generated by thermal expansion of the first and second joining members.

[0039] The pressing process S22 is a process of pressing the first joining member 10 and the second joining member 20 relative to each other so that pressure is applied to the first intended joining surface 12 and the second intended joining surface 22 under temperature conditions that allow the first joining member 10 and the second joining member 20 to be diffusion bonded (see Figure 3(a)).

[0040] In this specification, "temperature conditions under which the first and second bonding members can be diffusion bonded" refer to temperature conditions under which diffusion bonding is promoted compared to room temperature (however, temperature conditions below the melting points of the materials constituting the first and second bonding members). Diffusion bonding is classified as a solid-state bonding method that bonds the members to be bonded without melting them, and is a method of achieving bonding by the diffusion of atoms at the bonding interface.

[0041] The temperature suitable for diffusion bonding varies mainly depending on the type of material constituting the first bonding member 10 and the second bonding member 20, and the shape and state of the members. For this reason, it is difficult to give a generally appropriate numerical value, but for example, when the first bonding member 10 and the second bonding member 20 are made of ADC12, an aluminum-based material, it is thought that a temperature of about 500 to 560°C can be used.

[0042] The optimum pressure to be applied in the pressing step S22 varies greatly depending on the type of material constituting the first and second joining members 10 and 20, the shape and state of the first and second joining members 10 and 20, the temperature during diffusion bonding, etc. For this reason, it is difficult to give a generally appropriate numerical value, but it is considered preferable to apply a pressure on the order of MPa (approximately 1 to 10 MPa).

[0043] In order to diffusion bond the first bonding member 10 and the second bonding member 20 and obtain a high bonding strength, it is necessary to maintain the above temperature and pressure for a certain period of time. The optimum value for this time (maintenance time) varies depending on the type of material constituting the first bonding member 10 and the second bonding member 20, the shape and state of the first bonding member 10 and the second bonding member 20, the temperature and pressure during diffusion bonding, etc. For this reason, it is difficult to give a generally appropriate numerical value, but for example, 1 to 10 seconds / cm 3 It is thought that the value can be set to about 1 / 2 cm. 3 In the calculation of "volume", the cumulative total of the volumes of the first joint members 10 and the second joint members 20 is used.

[0044] The cooling step S24 is a step of cooling the first joining members 10 and the second joining members 20 while promoting recrystallization so as to eliminate chill layers in the first joining members 10. The cooling step S24 varies depending on the type of material constituting the first joining members 10 and the second joining members 20, the shape and state of the first joining members 10 and the second joining members 20, the specifications of the equipment used, the cooling conditions, etc. For this reason, it is difficult to give a generally appropriate numerical value, but it is thought that, for example, a period of approximately 30 minutes to 1 hour in a vacuum can be used. Note that, in the cooling step S24 as well, it is preferable to continue pressing the first joining members 10 and the second joining members 20 relative to each other following the pressing step S22.

[0045] The pressing step S22 and the cooling step S24 may be carried out consecutively using the same device, or each step may be carried out using a different device.

[0046] The die-cast assembly forming step S20 is preferably carried out in a vacuum or an inert gas, and more preferably in a vacuum. However, all or part of the die-cast assembly forming step S20 (e.g., the cooling step S24) can also be carried out in the presence of air.

[0047] In the die-cast joint body forming step S20, the application of heat and pressure and subsequent cooling causes the disappearance of chill layers and promotes recrystallization throughout the entire structure of the first joint members 10, which are die-cast members.

[0048] The "chill layer" is a relatively hard, high-density region (surface structure) that forms on the surface of a die-cast component due to the die-casting molding method. The chill layer is formed when the molten metal injected into the cavity adheres to the mold surface and is rapidly cooled. The presence of the chill layer can be identified by observation using a scanning electron microscope (SEM) or the like (see the examples described below). In die-cast components, the boundary between the chill layer and the internal structure deeper than it is not necessarily clear, but the region from the surface of the die-cast component to a depth of approximately 0.3 mm can generally be considered the chill layer.

[0049] The chilled layer is a region formed by rapid cooling, and therefore has many defects in the atomic structure. Therefore, the chilled layer is considered to have a structure suitable for atomic diffusion, which is essential for diffusion bonding. In other words, the chilled layer can be considered to be a region that contains the driving energy that promotes diffusion bonding.

[0050] In addition to the chill layer, die-cast components also contain microvoids. Microvoids are tiny gaps (on the order of micrometers or less) that form in various places in die-cast components due to the die-casting molding process. Microvoids are thought to be structures that originate mainly from gases contained in the molten metal or air entrained in the molten metal. Like the chill layer, microvoids are also thought to be structures that contribute to the diffusion bonding of die-cast components. In the die-cast joint formation process S20, microvoids are thought to be eliminated (disappear) as recrystallization progresses.

[0051] The die-cast member has a hard and brittle property (and thus a property that makes it difficult to bend without breaking) due to the structure described above. However, by performing the die-cast assembly formation step S20, it is possible to change the hard and brittle property that is derived from the structure unique to the die-cast member.

[0052] When the second joint members 20 are also die-cast members, the same phenomenon as that of the first joint members 10 occurs in the second joint members 20 by performing the die-cast joint body formation step S20.

[0053] Through the above steps, the die-cast joint body 1 can be manufactured (see FIGS. 3(b) and 3(c)).

[0054] 2. Die-cast joint 1 Next, the die-cast joint 1 according to embodiment 1 will be described. The die-cast joint 1 is a die-cast joint with excellent flexibility, and is manufactured by the method for manufacturing a die-cast joint according to embodiment 1 (see FIG. 3). The die-cast joint 1 has a first portion 10a derived from the first joint member 10 and a second portion 20a derived from the second joint member 20 (see FIGS. 3(b) and 3(c)).

[0055] The die-cast assembly 1 also has an internal structure 18a (internal space) formed in the internal structure-forming recess 18. The internal structure 18a can be used, for example, as a flow path for circulating a temperature-regulating fluid (such as a refrigerant). The structure and purpose of the internal structure 18a are not limited to those described above, and may be, for example, a structure in which multiple flow paths branch and merge without meandering, or a honeycomb structure that achieves both light weight and strength.

[0056] The die-cast assembly 1 according to embodiment 1 (the present invention) can be bent significantly without fracture, whereas the die-cast members before being assembled into an assembly cannot be bent significantly without fracture (see the examples described below). This difference between the present invention and the prior art is due to the structure of the die-cast assembly and the die-cast members (particularly, the growth of metal crystal grains and the presence of chill layers). However, due to the nature of these structures, it is impossible to specify the position, proportion, characteristics, etc. of the structure in a general manner.

[0057] Furthermore, even if it is theoretically possible to measure the structural differences between die-cast assemblies and die-cast parts, it would require enormous time and cost to manufacture or purchase die-cast assemblies and die-cast parts made of various materials, conduct detailed measurements on each sample, and statistically process the measurements to identify significant indicators and numerical values ​​that distinguish between die-cast assemblies and die-cast parts. Furthermore, the sheer number and variety of conventional die-cast parts, combined with the low reproducibility of manufactured products due to the die-casting process, make it impossible to unambiguously determine statistically significant numerical values. Therefore, it is virtually impractical to directly and precisely define the specific configuration that distinguishes between die-cast assemblies and die-cast parts, i.e., the features of the present invention, in terms of the structure or characteristics of the product.

[0058] If we attempt to identify a preferred die-cast joint 1 according to the embodiment primarily based on its structure and physical properties, we can say that "the die-cast joint 1 is a joint derived from a first joining member 10, at least a portion of which is a die-cast member, and at the joining interface P between the first joining member 10 and another member (second joining member 20), there is no chill layer derived from the first joining member 10, and the Vickers hardness of the outer surface derived from the first joining member 10 is 70% or less of the Vickers hardness of the first joining member 10 before joining." Such a die-cast joint 1 also has excellent flexibility. It is more preferable that the Vickers hardness of the outer surface derived from the first joining member 10 is 60% or less of the Vickers hardness of the first joining member 10 before joining.

[0059] The die-cast joint 1 can be used as a product as is, but it can also be post-processed to be made into a product, taking advantage of its ability to bend significantly without breaking. Furthermore, because the die-cast joint 1 has excellent flexibility, it is a joint suitable for processing that utilizes plastic deformation (for example, press processing). Therefore, the die-cast joint 1 can also be subjected to processing other than bending, such as cutting and drilling, without any problems.

[0060] For example, the die-cast joint 1 can be used as a radiator (heat sink) or heater with an internal flow path, but if the surface of the temperature control target O to be temperature controlled is curved, the die-cast joint 1 can be properly bent to be tightly attached to the temperature control target O (see Figure 4).

[0061] 3. Method for manufacturing die-cast assembly according to embodiment 1 and effects of die-cast assembly 1 The manufacturing method of the die-cast joint according to embodiment 1 is a manufacturing method of the die-cast joint for manufacturing a die-cast joint 1 having excellent flexibility, and includes a die-cast joint formation step S20. Therefore, the manufacturing method of the die-cast joint according to embodiment 1 is a manufacturing method of the die-cast joint that can manufacture a die-cast joint 1 that can be bent significantly without breaking (i.e., has excellent flexibility) using a die-cast member as the material (joining member), and can manufacture die-cast joints 1 having various external and internal shapes.

[0062] Furthermore, according to the method for manufacturing a die-cast assembly according to the first embodiment, it is possible to manufacture a die-cast assembly 1 that is superior in electrical conductivity and thermal conductivity compared to the die-cast member (first joining member 10).

[0063] Furthermore, according to the manufacturing method of the die-cast joint body of embodiment 1, when the method includes a cooling process S24 in which the first joint member 10 and the second joint member 20 are cooled while promoting recrystallization so as to eliminate the chill layer in the first joint member 10, it becomes possible to promote recrystallization while eliminating (eliminating) the chill layer, and as a result, it becomes possible to manufacture a die-cast joint body 1 that can be bent more greatly without breaking.

[0064] Furthermore, according to the manufacturing method of the die-cast joint body of embodiment 1, when the first planned joining surface 12 is a casting surface, the manufacturing cost of the first joining member 10 can be reduced, and diffusion bonding can be promoted by utilizing the chill layer and minute irregularities present on the surface of the first planned joining surface 12.

[0065] Furthermore, according to the manufacturing method of the die-cast joint body of embodiment 1, when the first intended joining surface 12 is a surface that has been processed by removing a thickness of 0.2 mm or less from the casting surface, a chill layer remains on the surface of the first intended joining surface 12, making it possible to utilize the chill layer to promote diffusion bonding.

[0066] Furthermore, according to the manufacturing method of the die-cast joint body of embodiment 1, when the thickness of the first joint member 10 in the direction perpendicular to the first planned joint surface 12 at the portion where the first planned joint surface 12 exists is within the range of 0.3 mm to 6 mm, it is possible to ensure sufficient strength and to facilitate temperature control during diffusion joining.

[0067] Furthermore, according to the manufacturing method of the die-cast joint body of embodiment 1, when the thickness of the second joint member 20 in the direction perpendicular to the second planned joint surface 22 at the portion where the second planned joint surface 22 exists is 0.05 mm or more and is equal to or less than the thickness of the first joint member 10 in the direction perpendicular to the first planned joint surface 12 at the portion where the first planned joint surface 12 exists, it is possible to ensure sufficient strength and to facilitate temperature control during diffusion joining.

[0068] Furthermore, according to the manufacturing method of the die-cast joint body of embodiment 1, when the main component of the material constituting the first joint member 10 is aluminum, magnesium, or zinc, it is possible to manufacture a die-cast joint body that has never been seen before using aluminum-based, magnesium-based, or zinc-based materials that are commonly used as die-cast members.

[0069] Furthermore, according to the method for manufacturing a die-cast joint body of embodiment 1, when the main component of the metal material constituting the second joint member 20 is copper, nickel, aluminum, zinc, or magnesium, it is possible to manufacture a die-cast joint body that has never been seen before by taking advantage of the properties of each metal material (for example, the softness of copper, nickel, aluminum, and zinc, and the properties of zinc and magnesium against hydrogen, etc.).

[0070] Furthermore, according to the manufacturing method of the die-cast joint body of embodiment 1, when the second joining member 20 is a die-cast member, it is possible to manufacture a die-cast joint body that makes use of the properties of the second joining member 20 as a die-cast member.

[0071] The die-cast joined body 1 according to the first embodiment is a die-cast joined body that can be bent significantly without breaking, unlike the die-cast members (first joining members 10) before joining.

[0072] [Embodiment 2] Fig. 5 is a diagram illustrating the bonding member preparation step S10a in embodiment 2. Fig. 5(a) is a perspective view of the first bonding member 30, Fig. 5(b) is a plan view of the first bonding member 30, Fig. 5(c) is a cross-sectional view taken along A3-A3 in Fig. 5(a), Fig. 5(d) is a perspective view of the second bonding member 40, Fig. 5(e) is a plan view of the second bonding member 40, and Fig. 5(f) is a cross-sectional view taken along A4-A4 in Fig. 5(e).

[0073] Figure 6 is a diagram illustrating the die-cast assembly forming step S20a in embodiment 2 and the die-cast assembly 2 according to embodiment 2. Figure 6(a) is a cross-sectional view showing the first and second joining members 30 and 40 being pressed relative to each other, Figure 6(b) is a cross-sectional view of the manufactured die-cast assembly 2, and Figure 6(c) is a perspective view of the manufactured die-cast assembly 2. Figures 6(a) and 6(b) are cross-sectional views corresponding to Figures 5(c) and 5(f).

[0074] The thick arrows indicated by the symbol P in FIG. 6(a) indicate that the first joining members 10 and the second joining members 20 are being pressed relative to one another. Note that in FIG. 6(a), thick arrows pointing in four different directions centered on the symbol P are shown, but this does not indicate that a moving force (pressing force) is being applied in only four directions, but rather that a moving force (pressing force) is being applied in all directions from the inside of the first joining members 30. Note that FIG. 6(a) shows a state in which the second joining members 40 are fixed and a moving force is applied to the first joining members 30 (pressing force is applied from the first joining members 30 side), but a base, jig, etc. for fixing the second joining members 40 are not shown.

[0075] FIG. 7 is a perspective view showing the state in which the die-cast joined body 2 according to the second embodiment is disposed inside a tubular member T. As shown in FIG.

[0076] The method for manufacturing a die-cast joint body according to embodiment 2 is basically the same as the method for manufacturing a die-cast joint body according to embodiment 1, but differs in the shapes of the first and second joining members used. The method for manufacturing a die-cast joint body according to embodiment 2 will be described below, but explanations of matters similar to those in the method for manufacturing a die-cast joint body according to embodiment 1 may be omitted.

[0077] The method for manufacturing a die-cast assembly according to the second embodiment includes a joining member preparation step S10a and a die-cast assembly formation step S20a, which includes a pressing step S22a and a cooling step S24a. The flow of each step is the same as in the method for manufacturing a die-cast assembly according to the first embodiment, and therefore a flowchart is not shown.

[0078] The joining member preparing step S10a is a step of preparing the first joining members 30 and the second joining members 40 (see FIG. 5). The first joining members 30 and the second joining members 40 will be described below.

[0079] The first joining member 30 is a die-cast member having a tubular shape. The first joining member 30 has a first intended joining surface 32 (see FIGS. 5(a) to 5(c)). The first joining member 30 may have a structure such as a recess for forming an internal structure formed therein.

[0080] The second joint member 40 is a member made of a metallic material and has a tubular shape with a larger diameter than the first joint member 30. The second joint member 40 has a second intended joint surface 42 (see FIGS. 5(d) to 5(f)).

[0081] The die-cast joint formation process S20a is a process in which the first joining member 30 and the second joining member 40 are diffusion-bonded to form the die-cast joint 2 by pressing the first joining member 30 and the second joining member 40 relative to each other so that pressure is applied to the first planned joining surface 32 and the second planned joining surface 42 under temperature conditions that allow the first joining member 30 and the second joining member 40 to be diffusion-bonded (see Figure 6(a)).

[0082] 6(a), the die-cast joint body formation process S20a is not limited to pressing by fixing the second joint members 40 and applying a moving force to the first joint members 30 (applying a pressing force from the first joint members 30 side). The first joint members 30 may be fixed and pressed by applying a moving force to the second joint members 40 (applying a pressing force from the second joint members 40 side), or by applying a moving force to both the first joint members 30 and the second joint members 40 (applying a pressing force from both the first joint members 30 side and the second joint members 40 side).

[0083] In addition, the moving force (pressing force) may be generated by a mechanism that applies pressure from the outside (such as an isostatic pressing mechanism), or may be generated by thermal expansion of the first joining member 30 and the second joining member 40.

[0084] The pressing process S22a is a process of pressing the first joining member 30 and the second joining member 40 relative to each other so that pressure is applied to the first intended joining surface 32 and the second intended joining surface 42 under temperature conditions that allow the first joining member 30 and the second joining member 40 to be diffusion bonded (see Figure 6(a)).

[0085] The cooling step S24a is a step of cooling the first joining members 30 and the second joining members 40 while promoting recrystallization so as to eliminate chill layers in the first joining members 30.

[0086] Through the above steps, the die-cast joined body 2 can be manufactured (see FIGS. 6(b) and 6(c)).

[0087] The die-cast joint 2 is manufactured by the method for manufacturing a die-cast joint according to embodiment 2 (see FIG. 6). The die-cast joint 2 has a first portion 30a derived from the first joint member 30 and a second portion 40a derived from the second joint member 40 (see FIGS. 6(b) and 6(c)).

[0088] The die-cast joint 2 can be used, for example, as a lining for a tubular member T used in piping (especially in piping through which substances that induce deterioration of piping, such as hydrogen, are passed) (see FIG. 7). There are no particular limitations on the method for fixing the die-cast joint 2 to the inner surface of the tubular member T, but since the die-cast joint 2 has excellent flexibility, it is also possible to adhere the die-cast joint 2 and the tubular member T to each other using a method such as electromagnetic forming.

[0089] Furthermore, when the die-cast joint 2 is used as a lining for a tubular member T or the like through which hydrogen flows, it is preferable that at least one of the first joint member 30 and the second joint member 40 be made of a material that has a high ability to trap hydrogen or a material that is resistant to hydrogen embrittlement.

[0090] The method for manufacturing a die-cast assembly according to embodiment 2 differs from that for manufacturing a die-cast assembly according to embodiment 1 in the shapes of the first and second joining members used, but is a method for manufacturing a die-cast assembly 2 with excellent flexibility, and includes a die-cast assembly forming step S20a. Therefore, like the method for manufacturing a die-cast assembly according to embodiment 1, the method for manufacturing a die-cast assembly according to embodiment 2 is a method for manufacturing a die-cast assembly 2 using die-cast members as materials (joining members) that can be bent significantly without breaking (i.e., has excellent flexibility), and can also manufacture die-cast assembly 2 with a variety of external and internal shapes.

[0091] The method for manufacturing a die-cast joint body according to embodiment 2 is basically the same as the method for manufacturing a die-cast joint body according to embodiment 1, and therefore further has the corresponding effects among the effects possessed by the method for manufacturing a die-cast joint body according to embodiment 1.

[0092] The die-cast joined body 2 according to the second embodiment is a die-cast joined body that can be bent significantly without breaking, unlike the die-cast members (first joining members 30) before joining.

[0093] [Example] The inventors of the present invention have actually implemented the method for manufacturing a die-cast assembly of the present invention, manufactured die-cast assembly, and conducted experiments. The results of the experiments on the die-cast assembly will be described below.

[0094] 1. Manufacturing of die-cast joints Figure 8 is a diagram illustrating a die-cast assembly 3 according to an embodiment and a comparative die-cast member 4. Figure 8(a) is a plan view of the die-cast assembly 3 according to the embodiment, Figure 8(b) is a front view of the die-cast assembly 3 according to the embodiment, and Figure 8(c) is a front view of the comparative die-cast member 4. Note that the shape of the die-cast member 4 in plan view is the same as that of the die-cast assembly 3, so a plan view of the die-cast member 4 is omitted.

[0095] First, a die-cast assembly 3 was manufactured as a test piece (sample) for a bending test based on the manufacturing method of the die-cast assembly of the present invention (see FIG. 8). The die-cast assembly 3 has a first portion 50a derived from the first joining member (not shown) and a second portion 60a derived from the second joining member (not shown).

[0096] In the examples, a mixture of recycled ingots and virgin ADC12 ingots (Cu: 1.92%, Si: 10.26%, Mg: 0.26%) was used as the material for molding the first and second bonding members. The composition of the material is shown in Table 1. [Table 1]

[0097] The above materials were used to mold first and second joining members into flat plates measuring 100 mm in width, 100 mm in length, and 3 mm in thickness using a conventional die casting method. A DC250R casting machine manufactured by Shibaura Machine Co., Ltd. was used. The conditions for the conventional die casting method were a casting pressure of 102 MPa, a cycle time of 20 seconds, a filling speed of 1.65 m / s (high speed), 0.15 m / s (low speed), a mold temperature of 120°C, and a melting temperature of 690°C. Furthermore, Dieslick (registered trademark) No. 100S, purchased from Nichibei Co., Ltd., was used as a mold release agent.

[0098] Next, the first and second joining members were diffusion bonded in a stacked state. The diffusion bonding was performed using a hybrid diffusion bonding machine HHVS-30 / 30 / 35-RF manufactured by IHI Corporation. The temperature during diffusion bonding (pressing) was 560°C, the pressing force was 2 MPa, and the pressing force was held for 60 minutes. The diffusion bonding was performed under vacuum conditions (6.0 x 10 -2 The first and second joining members were not subjected to surface processing or treatment, and the surfaces to be joined were as-cast surfaces.

[0099] After joining, the die-cast joint 3 was cut to a width of 20 mm, producing a die-cast joint 3 with a width of 20 mm, length of 100 mm, and thickness of 6 mm (see Figures 8(a) and 8(b)). The bending test (three-point bending test) described below was conducted with reference to the Japanese Industrial Standards (JIS) "Metallic Material Bending Test Method JIS Z 2248:2006," and the shape of the die-cast joint 3 also conforms to the No. 1 test piece of the standard.

[0100] For comparison with the die-cast joint 3, a die-cast member 4 was also produced as a cast material (see Figure 8(c)). The die-cast member 4 was produced by molding a 6 mm thick flat plate-shaped member using the same material as the die-cast joint 3 using a standard die-casting method, and then cutting the member. The conditions for the standard die-casting method for the die-cast member 4 were as follows: casting pressure: 99 MPa, cycle time: 27 seconds, filling speed: 1.69 m / s (high speed), 0.15 m / s (low speed), mold temperature: 120°C, and melting temperature: 690°C.

[0101] Furthermore, for the purpose of SEM observation, a die-cast joined body 3a (not shown) was produced under different joining conditions from those of the die-cast joined body 3. In joining the die-cast joined body 3a, the temperature during diffusion joining (pressing) was 530°C, the pressing force was 2 MPa, and the pressing force was held for 70 minutes.

[0102] For comparison with the die-cast assembly 3a, a bolted die-cast member (not shown) was also produced by overlapping the first and second joining members and fastening them with bolts. Because the bolted die-cast member was not joined, the interface between the first and second joining members remained the same as the intended joining surface.

[0103] 2. Bending test and surface hardness measurement Fig. 9 is a schematic diagram showing the state of a three-point bending test in the example, in which the symbol S indicates a sample (die-cast joined body 3 or die-cast member 4). Figure 10 shows the results of a bending test on the die-cast assembly 3 according to the example. Figure 10(a) is a graph of the bending test results, Figure 10(b) is a photograph of the entire die-cast assembly 3 when it broke, and Figure 10(c) is a photograph of the fractured point and its vicinity when the die-cast assembly 3 broke. The vertical axis of the graph in Figure 10(a) represents the load (unit: N), and the horizontal axis represents the displacement (unit: mm), which is the amount of pressure applied by the pressure tool. "1 min" represents the time point 1 minute after the start of the test, "2 min" represents the time point 2 minutes after the start of the test, and "BP" represents the time point at which the fracture occurred. Figure 11 shows the results of a bending test on a comparative die-cast member 4. Figure 11(a) is a graph of the bending test results, Figure 11(b) is a photograph of the entire die-cast member 4 when it broke, and Figure 11(c) is a photograph of the fractured point and its vicinity when the die-cast member 4 broke. The vertical axis of the graph in Figure 11(a) represents the load (unit: N), and the horizontal axis represents the displacement (unit: mm), with "1 min" representing the time point one minute after the start of the test and "BP" representing the time point at which the die-cast member broke.

[0104] Next, a bending test was conducted on the manufactured die-cast joint 3 and die-cast member 4 as samples. A three-point bending test was used for the bending test, and the conditions were as follows: distance between supports L: 40 mm, pressure probe tip diameter R1: 5 mm, and support diameter R2: 5 mm (see Figure 9). The test machine used was A&D Co., Ltd.'s Tensilon universal material testing machine RTG-1310, and the crosshead displacement speed was 0.44 mm / min.

[0105] As a result, it was confirmed that the die-cast assembly 3 required a lower load to bend than the die-cast member 4 and could withstand approximately 1.5 times the displacement (see Figures 10 and 11). Therefore, it was confirmed that the die-cast assembly of the present invention can be bent to a greater extent without breaking compared to the die-cast member.

[0106] The three-point bending test is a test to measure the strength of the entire sample, not the strength of the bonded interface of the bonded body. However, in the die-cast bonded body 3, the base material (first part or second part) fractured before peeling at the bonded interface was observed (see Figures 10(b) and 10(c)). Because diffusion bonding is a bonding method that integrates components at the atomic structure level, as long as diffusion bonding is performed appropriately, the main issue with bending is the properties of the base material.

[0107] Furthermore, because the three-point bending test is a test in which measurements are taken by applying a local load to the sample and destroying it, the results obtained do not represent the actual limit of bending workability. The above results are meaningful in terms of comparing the die-cast assembly 3 with the die-cast member 4.

[0108] Next, the surface hardness of the die-cast assembly 3 and the die-cast member 4 was measured. A Matsuzawa Corporation Vickers hardness tester was used as the measuring machine. The test force was 5 kgf. As a result, the surface hardness of the die-cast assembly 3 was 65.5 HV, while the surface hardness of the die-cast member 4 was approximately 122.7 HV. This confirmed that the surface hardness was reduced by about half by performing diffusion bonding. In general, a lower surface hardness is advantageous for bending processing, and from this perspective, it was confirmed that the die-cast assembly of the present invention can be bent to a greater extent without fracture compared to die-cast members.

[0109] 3. SEM Observation Fig. 12 shows the results of observation of the vicinity of the interface in the die-cast joint 3a according to the example, where Fig. 12(a) is an SEM image showing the joint interface P1 of the die-cast joint 3a and its vicinity, and Fig. 12(b) is an image showing the results of elemental analysis of silicon. Figure 13 shows the results of observation of the vicinity of the interface of a bolted die-cast member, where Figure 13(a) is an SEM image showing the interface P2 and its vicinity of the bolted die-cast member, and Figure 13(b) is an image showing the results of elemental analysis of silicon.

[0110] Next, the interfaces of the die-cast joined body 3a and the bolted die-cast members were observed by SEM (see FIG. 12). SEM images were obtained using a JEOL JCM-6000Plus NeoScope (registered trademark) tabletop scanning electron microscope. Elemental analysis was also performed using an energy dispersive X-ray spectrometer, JEOL JED-2300(S).

[0111] The bolted die-cast components had a relatively simple structure as it was after casting, including the primary α phase, dendrite cells, and eutectic Si phase, and the grain size near the interface P2 was approximately 5 to 10 μm (see the area near the white arrow in Figure 13(a)). Furthermore, in the bolted die-cast components, silicon (Si) was uniformly distributed within the structure (see Figure 13(b)).

[0112] On the other hand, it was confirmed that the grain boundaries had disappeared in the die-cast bonded body 3a (see FIG. 12(a)). This is thought to be due to the annealing effect caused by heating and cooling. In addition, the darkest areas in FIG. 12(a) are caused by segregated silicon (Si crystals) (see FIG. 12(b)). It was confirmed that the silicon had become spherical, with some of it spanning the bonded interface P1. This is thought to indicate that interdiffusion of atoms had occurred across the interface.

[0113] From the disappearance of grain boundaries and the change in silicon distribution, it is believed that the chill layer specific to die-cast members has disappeared in the die-cast joint body 3a.

[0114] Although the present invention has been described based on the above-mentioned embodiments, the present invention is not limited to the above-mentioned embodiments. The present invention can be embodied in various forms without departing from the spirit of the present invention, and for example, the following modifications are also possible.

[0115] (1) The overall and partial shapes of the first and second joint members in the above embodiments are merely examples, and any shape may be used as long as it does not deviate from the scope of the present invention.

[0116] (2) In the first and second joining members, the presence or absence of the plate-like portion, the recess for forming the internal structure, the protrusion, the receiving hole, etc. can be determined as needed.

[0117] (3) The materials constituting the first and second joint members described in the above embodiments are merely examples, and materials containing metals other than those mentioned above as their main components may also be used.

[0118] (4) The method for manufacturing a die-cast member of the present invention may further include steps other than the joining member preparing step and the die-cast assembly forming step.

[0119] (5) The applications of the die-cast assembly produced by the method of the present invention for producing die-cast members are not limited to radiators, heaters, and linings of tubular members.

[0120] (6) The method for manufacturing a die-cast member according to the second embodiment is illustrated as manufacturing a die-cast assembly 2 having a round tube (round pipe) shape, but the present invention is not limited to this. The die-cast assembly manufactured by the method for manufacturing a die-cast member according to the present invention can have any cross-sectional shape, such as a square tube (square pipe).

[0121] (7) In the manufacturing method of the die-cast member according to the second embodiment, the second joining member 40 is prepared as a tubular member having a larger diameter than the first joining member 30, and a die-cast assembly 2 is manufactured in which the second portion 40a exists on the outer periphery. However, the present invention is not limited to this. In the manufacturing method of the die-cast member according to the present invention, the first joining member may be prepared as a tubular member having a larger diameter than the second joining member, and a die-cast assembly 2 in which the first portion exists on the outer periphery may be manufactured.

[0122] (8) In each of the above embodiments, the die-cast joint body is manufactured using one first joint member and one second joint member, but the present invention is not limited to this. There may be multiple first joint members, and there may also be multiple second joint members. In this case, the die-cast joint body to be manufactured will have multiple first portions derived from the first joint member and multiple second portions derived from the second joint member. [Explanation of symbols]

[0123] 1, 2, 3... die-cast joint, 4... comparative die-cast member, 10, 30... first joining member, 10a, 30a, 50a... first portion, 12, 32... first intended joining surface, 14... plate-shaped portion, 16... protruding portion, 18... recess for forming internal structure, 18a... internal structure, 20, 40... second joining member, 20a, 40a, 60a... second portion, 22, 42... second intended joining surface, 24... receiving hole, O... temperature control target, P... joining interface, T... tubular member

Claims

1. A method for manufacturing a die-cast joint body for manufacturing a die-cast joint body having excellent flexibility, comprising: a joining member preparing step of preparing a first joining member which is a die-cast member and has a first planned joining surface, and a second joining member which is made of a metal material and has a second planned joining surface; a die-cast joint formation process of forming the die-cast joint by pressing the first joint member and the second joint member relative to each other so that pressure is applied to the first planned joining surface and the second planned joining surface under a temperature condition where the first joint member and the second joint member can be diffusion-bonded, thereby diffusion-bonding the first joint member and the second joint member to form the die-cast joint, The die-cast joint body forming step includes: a pressing step of pressing the first bonding member and the second bonding member relatively to each other so that pressure is applied to the first planned bonding surface and the second planned bonding surface under the temperature condition that allows diffusion bonding of the first bonding member and the second bonding member; a cooling step of cooling the first joining member and the second joining member while promoting recrystallization so as to eliminate a chill layer in the first joining member.

2. 2. The method for manufacturing a die-cast joint body according to claim 1, wherein the first planned joining surface is a casting surface.

3. 2. The method for manufacturing a die-cast joint body according to claim 1, wherein the first intended joining surface is a surface obtained by removing a thickness of 0.2 mm or less from the casting surface.

4. The method for manufacturing a die-cast joint body described in claim 1, characterized in that in the first joint member, the thickness along the direction perpendicular to the first planned joint surface at the portion where the first planned joint surface exists is in the range of 0.3 mm to 6 mm.

5. The method for manufacturing a die-cast joint body described in claim 1, characterized in that in the second joint member, the thickness along the direction perpendicular to the second planned joint surface at the portion where the second planned joint surface exists is 0.05 mm or more, and is less than the thickness along the direction perpendicular to the first planned joint surface at the portion where the first planned joint surface exists in the first joint member.

6. 2. The method for manufacturing a die-cast joint body according to claim 1, wherein a main component of the material constituting the first joint member is aluminum, magnesium, or zinc.

7. 2. The method for manufacturing a die-cast joint body according to claim 1, wherein the main component of the metal material constituting the second joint member is copper, nickel, aluminum, zinc, or magnesium.

8. 2. The method for manufacturing a die-cast joint body according to claim 1, wherein the second joint member is a die-cast member.

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