Method for joining dissimilar metal components
The method addresses the issue of brittle intermetallic compound formation by using precise dimensional and temperature measurements to join dissimilar metals with high bonding strength, ensuring reliable connections.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- TOYOTA JIDOSHA KK
- Filing Date
- 2023-06-07
- Publication Date
- 2026-07-29
AI Technical Summary
Joining dissimilar metal components, such as non-ferrous and ferrous metals, results in the formation of brittle intermetallic compounds, leading to variations in joining strength and reduced reliability due to dimensional deformation caused by temperature changes.
A method involving a casting process using a mold to form a cast member, followed by precise measurement of external dimensions and surface temperature, and identification of a joining member with a lower thermal expansion coefficient, allowing for controlled joining of dissimilar metals.
Enables high bonding strength between dissimilar metal components by selecting a suitable joining member based on measured dimensions and temperature, preventing deformation and ensuring a strong joint.
Smart Images
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Abstract
Description
Technical Field
[0001] The present disclosure relates to a method for joining dissimilar metal members.
Background Art
[0002] For example, when connecting dissimilar metal members, such as a non-ferrous metal Made member and a member made of a ferrous metal (steel), if the two members are directly joined by welding or the like, a brittle intermetallic compound is formed at the joining interface. As a result, the variation in joining strength becomes large and the reliability of the joining decreases. Therefore, a method is known in which a casting product in which a ferrous metal member is cast in a non-ferrous metal member to integrate the two members is manufactured, and the casting product is joined to another member.
[0003] Patent Document 1 discloses a casting product that is joined to a mating member, and includes a plurality of joining chips that are joined at respective joining surfaces of the mating member at a plurality of locations, and a casting metal material that is made of a metal material different from the mating member and that casts while dispersing the plurality of joining chips and exposing at least one surface of each joining surface.
[0004] According to the technique described in Patent Document 1, since the plurality of joining chips that are dispersed and cast in the casting metal material are respectively joined to a plurality of locations of the mating member, the size of the joining chips can be reduced. As a result, it is described that the stress generated in the casting metal material due to the shrinkage accompanying the cooling of the casting metal material can be suppressed.
Prior Art Documents
Patent Documents
[0005]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0006] Here, when a cast component (cast metal material) is formed using a mold, the temperature of the cast component obtained immediately after the mold is opened changes over time. Non-ferrous metals Made When joining dissimilar metal components, such as a cast component and a ferrous metal joining component, there was a problem in that the dimensional deformation of the cast component due to temperature changes reduced the joint strength between the dissimilar metal components.
[0007] This disclosure was made to solve such problems and aims to provide a method for joining dissimilar metal members that can join dissimilar metal members with high bonding strength. [Means for solving the problem]
[0008] A method for joining dissimilar metal members according to one embodiment includes a casting step of forming a cast member using a mold, a dimension measurement step of measuring the external dimensions of the cast member inside the mold or the cast member removed from the mold, a temperature measurement step of measuring the surface temperature of the mold or the cast member, a joining member identification step of identifying a joining member having a hardness determined based on the external dimensions and surface temperature measured within a predetermined time after the mold is opened or the cast member is removed from the mold, and a joining step of joining at least a part of the identified joining member to the cast member, wherein the joining member is made of a dissimilar metal material having a lower coefficient of thermal expansion than the metal material constituting the cast member. [Effects of the Invention]
[0009] This disclosure provides a method for joining dissimilar metal members that can join dissimilar metal members with high bonding strength. [Brief explanation of the drawing]
[0010] [Figure 1] This is a diagram illustrating the method for joining dissimilar metal members according to Embodiment 1. [Figure 2] This is a flowchart showing a method for joining dissimilar metal members according to Embodiment 1. [Modes for carrying out the invention]
[0011] Embodiment 1 Embodiments of this disclosure will be described below with reference to the drawings. However, this disclosure is not limited to the embodiments described below. Also, for clarity, the following description and drawings have been simplified as appropriate.
[0012] First, Figure 1 is a diagram illustrating a method for joining dissimilar metal members according to Embodiment 1. As shown in Figure 1, in this embodiment, the method for joining dissimilar metal members involves joining the cast member 1 and the joining member 2, which is made of a different metal material from the cast member 1, by the difference in thermal expansion between the two.
[0013] The cast member 1 is made of a non-ferrous metal such as aluminum, magnesium, or zinc. In this embodiment, the cast member 1 is made of aluminum. The cast member 1 is cast into a predetermined product shape by a casting method such as die casting, gravity casting, or low-pressure casting. In this embodiment, the cast member 1 has a rectangular parallelepiped shape. Furthermore, the cast member 1 is provided with a hole 10 into which at least a portion of the joining member 2 is inserted.
[0014] The joining member 2 is made of a different metal material having a lower coefficient of thermal expansion than the metal material constituting the cast member 1. The joining member 2 is, for example, an iron-based metal including iron, such as various alloy steels or cast iron. In this embodiment, the joining member 2 is made of cast iron. The joining member 2 has a rod shape corresponding to the shape of the hole 10. In this embodiment, the joining member 2 has a cylindrical shape corresponding to the shape of the hole 10.
[0015] The cast member 1 is manufactured, for example, using the die-casting apparatus 100 shown in Figure 1. The die-casting apparatus 100 is a device that manufactures a cast member 1 corresponding to the shape of the cavity 30 by die-casting, in which high-temperature molten metal, such as molten aluminum, is filled into a cavity 30 formed by a mold 20, and then the molten metal is cooled and solidified.
[0016] The die-casting apparatus 100 includes a mold 20 for forming a cavity 30, an injection device for injecting molten metal into the cavity 30, a clamping device for opening and closing the mold 20 and clamping it, a depressurization device for supplying negative pressure into the cavity 30, and a transport device for removing the cast member 1 from inside the mold 20.
[0017] The mold 20 includes a fixed mold 21, a movable mold 22 that can be clamped and opened by moving relative to the fixed mold 21, and a casting pin 23 attached to the movable mold 22. The mold 20 is clamped together with the fixed mold 21 and the movable mold 22 to form a cavity 30 corresponding to the shape of the cast member 1 between the fixed mold 21 and the movable mold 22. A gate 31 and a runner 32 are further formed in the clamped mold 20. The casting pin 23 is a casting pin that forms a casting hole as a hole 10 in the cast member 1. The casting pin 23 has, for example, a cylindrical shape. The tip of the casting pin 23 protrudes into the cavity 30. The casting pin 23 may also be attached to the fixed mold 21.
[0018] The injection molding device comprises an injection sleeve 41, a plunger tip 42, a rod 43, and a plunger driving means. The injection sleeve 41 communicates with a runner 32 and is coupled to a fixed mold 21. A molten metal inlet 44 is formed at the rear end of the injection sleeve 41 for pouring molten metal into the injection sleeve 41. The plunger tip 42 is positioned inside the injection sleeve 41 so as to be able to move back and forth along the longitudinal direction of the injection sleeve 41. The plunger driving means drives the plunger tip 42 back and forth via a rod 43 connected to the plunger tip 42.
[0019] The movable mold 22 is provided with a vacuum valve 52 via a vacuum passage 51 whose one end opens into the cavity 30. A vacuum device including a vacuum pump is connected to the vacuum valve 52. When the vacuum valve 52 is opened, the die-casting device 100 is configured to supply negative pressure from the vacuum device into the cavity 30.
[0020] The mold clamping device relatively moves a movable die plate to which the movable mold 22 is fixed by the driving force of the mold clamping driving means with respect to a fixed die plate to which the fixed mold 21 is fixed. Thereby, the mold clamping device performs mold closing and mold opening for opening and closing the mold 20 and mold clamping of the mold 20.
[0021] After taking out the casting member 1 from inside the mold 20 to the outside of the mold 20, the conveying device conveys the taken-out casting member 1 along the conveying path outside the mold 20. As the conveying device, for example, a robot arm having an arm for gripping the casting member 1 can be used.
[0022] Furthermore, the die-casting device 100 includes a photographing camera 60 for photographing the casting member 1 taken out from inside the mold 20, a thermoviewer 70 for measuring the surface temperature of the casting member 1 taken out from inside the mold 20, and a control device 80 for controlling the operation of the die-casting device 100.
[0023] The photographing camera 60 may be, for example, a 2D camera for photographing a 2D image or a 3D camera for photographing a 3D image. The photographing camera 60 is provided above the conveying path. The photographing camera 60 is provided at a position where it can photograph the casting member 1 within a predetermined time (for example, within 10 seconds) after taking out the casting member 1 from inside the mold 20. The photographing camera 60 transmits the image data of the photographed image of the casting member 1 to the control device 80.
[0024] The thermoviewer 70 generates two-dimensional temperature distribution image data from data captured by a thermocamera 71, which is connected wirelessly or via a wired connection. The thermocamera 71 is positioned above the transport path, alongside the imaging camera 60. The thermocamera 71 is positioned to detect infrared light emitted from the cast member 1 within a predetermined time (e.g., within 10 seconds) after the cast member 1 is removed from the mold 20. Based on the data captured by the thermocamera 71, the thermoviewer 70 generates image data of a temperature distribution image showing the surface temperature distribution of the cast member 1. The thermoviewer 70 transmits the generated image data to the control device 80.
[0025] The die-casting apparatus 100 may have a thermograph instead of a thermoviewer 70. By having an image measuring device such as a thermoviewer 70 or a thermograph, the die-casting apparatus 100 can precisely measure the temperature of the cast member 1.
[0026] Here, the predetermined time from removing the cast member 1 from the mold 20 until taking the photograph is set according to the size of the cast member 1, etc. For example, if the temperature of the cast member 1 immediately after removal is 200 to 300°C, the predetermined time from removing the cast member 1 from the mold 20 until taking the photograph can be set to 30 seconds.
[0027] The control device 80 consists of a processor that performs various calculations, a computer equipped with memory such as ROM (Read Only Memory) and RAM (Random Access Memory), and input / output interfaces. The control device 80 functions as a die-casting control unit that controls the operation of the injection device, clamping device, depressurization device, and transport device by having the processor execute a casting program pre-stored in the memory, and also functions as a detection unit that detects the state of the cast member 1. In addition to the above-mentioned program, the memory stores multiple types of hardness information, surface temperature thresholds, and external dimension thresholds.
[0028] The control device 80 is connected to the injection device, clamping device, depressurization device, and conveying device, etc., by control lines. The control device 80 controls the operation of each of the injection device, clamping device, depressurization device, and conveying device, etc., by supplying control signals to each of them via the control lines. The control device 80 is also connected to the imaging camera 60 and the thermoviewer 70, respectively, by detection signal lines. The control device 80 detects the state of the cast member 1 from the detection signals supplied from the imaging camera 60 and the thermoviewer 70, respectively, via the detection signal lines.
[0029] The control device 80 may be connected to an input device operated by the operator, a display device that shows various values, etc. Furthermore, some or all of the functions of each part of the die-casting apparatus 100 may be implemented by hardware circuits.
[0030] The die-casting apparatus 100, in accordance with the control device 80, molds the cast member 1 with the mold 20 clamped, and then removes and transports the cast member 1 using a transport device with the mold 20 open. After that, the die-casting apparatus 100 detects the state of the molded cast member 1 using a photographic camera 60 and a thermal camera 71.
[0031] The control device 80 analyzes the image data received from the camera 60 and the thermoviewer 70, respectively. Based on the image data received from the camera 60, the control device 80 measures the external dimensions of the cast member 1. The control device 80 also measures the surface temperature of the cast member 1 based on the image data received from the thermoviewer 70.
[0032] The control device 80 may determine whether the cast member 1 is suitable to be joined to the joining member 2 based on the measured surface temperature and external dimensions. If the control device 80 determines that the cast member 1 is suitable, it may then identify the joining member 2, as described later. On the other hand, if the control device 80 determines that the cast member 1 is unsuitable, it may control the transport device to remove the cast member 1 from the transport path while it is being transported.
[0033] The control device 80 identifies the joining member 2 having a hardness determined based on the measured surface temperature and external dimensions. The control device 80 determines the hardness of the joining material by referring to the hardness information stored in memory. The control device 80 selects hardness information from among multiple types of hardness information stored in memory that corresponds to the combination of surface temperature and external dimensions.
[0034] The control device 80 then controls the transport device to set the cast member 1 in a suitable location where joining with the joining member 2 will take place. Once the cast member 1 is set, the control device 80 controls the insertion device for inserting the joining member 2 so that at least a portion of the identified joining member 2 is inserted into the hole 10 of the cast member 1. In this way, the control device 80 controls the joining of at least a portion of the identified joining member 2 to the cast member 1.
[0035] Referring to Figure 1 and Figure 2, an example of a method for joining dissimilar metal members according to this embodiment will be described. Figure 2 is a flowchart of the method for joining dissimilar metal members according to Embodiment 1. As shown in Figure 2, the method for joining dissimilar metal members according to this embodiment has steps S1 to S5.
[0036] In the casting process, the cast member 1 is formed using a mold 20 (step S1). The casting process includes, for example, a mold clamping process, a pouring process, an injection filling process, a solidification process, a mold opening process, and a removal process.
[0037] First, in the mold clamping process, the mold 20 is clamped by a mold clamping device (step S1-1). By clamping the mold 20, the cavity 30 is formed. Next, in the pouring process, a predetermined amount of molten metal is poured into the injection sleeve 41 from the pouring port 44 (step S1-2). If the molten metal is aluminum, the temperature of the molten metal is, for example, about 700°C.
[0038] Next, in the injection filling process, the plunger tip 42 is driven forward to inject and fill the cavity 30 of the mold 20 with molten metal from the injection sleeve 41 (step S1-3). The injection filling process may include a low-speed injection process in which the molten metal in the injection sleeve 41 is pressed at a low speed while the pressure reducing valve 52 is opened to reduce the pressure inside the cavity 30, and a high-speed injection process in which the molten metal in the injection sleeve 41 is pressed at a high speed to inject and fill the cavity 30 of the mold 20 with molten metal at a high speed. Performing the low-speed injection process suppresses air entrapment and increases the filling rate of the molten metal. Performing the high-speed injection process allows the molten metal to be quickly filled into the cavity 30 before it solidifies.
[0039] Next, in the solidification process, the molten metal filled in the cavity 30 is cooled and solidified (steps S1-4). This allows the cast member 1 corresponding to the shape of the cavity 30 to be formed. Holes 10 are formed in the cast member 1 formed in this way by the casting pins 23. In the solidification process, the molten metal is cooled to a temperature at which the cast member 1 can be removed (for example, about 200°C).
[0040] Next, in the mold opening process, after forming the cast member 1 as described above, the mold 20 is opened by the mold clamping device (step S1-5). Then, in the removal process, the cast member 1 is removed from the mold 20 by the conveying device (step S1-6). After that, the cast member 1 is conveyed to the next process by the conveying device. The cast member 1 removed from the mold 20 is quickly conveyed by the conveying device to the imaging area of the camera 60 and the detection area of the thermal camera 71.
[0041] In the dimensional measurement process, the camera 60 captures image data of the cast member 1 within a predetermined time after it has been removed from the mold 20. Then, in the dimensional measurement process, the control device 80 measures the external dimensions of the cast member 1 based on the image data captured by the camera 60 (step S2).
[0042] In the temperature measurement process, a thermal camera 71 detects infrared light emitted from the cast member 1 within a predetermined time after it has been removed from the mold 20. Then, in the temperature measurement process, the control device 80 measures the surface temperature of the cast member 1 based on the image data of the temperature distribution image generated by the thermal viewer 70 from the data captured by the thermal camera 71 (step S3).
[0043] In the joining member identification process, the control device 80 determines whether a cast member 1 is suitable to be joined to the joining member 2 based on the surface temperature and external dimensions measured within a predetermined time. The control device 80 determines that the cast member 1 is suitable if the measured surface temperature is below a preset surface temperature threshold and the measured external dimensions are below a preset external dimension threshold. If the control device 80 determines that the cast member 1 is suitable, it proceeds to the identification of the joining member 2.
[0044] In the joining member identification process, a joining member 2 having a hardness determined based on the external dimensions and surface temperature measured within a predetermined time is identified. In this embodiment, the memory of the control device 80 stores three types of hardness information, indicating one of the following: "highest hardness," "slightly higher hardness," or "normal hardness." Therefore, the control device 80 selects one type of hardness information from the three types of hardness information according to the combination of surface temperature and external dimensions. The hardness information shows a correlation such that, for example, the hardness increases as the external dimensions and surface temperature of the cast member 1 increase.
[0045] On the other hand, the control device 80 determines that the cast member 1 is unsuitable if the measured surface temperature exceeds a preset surface temperature threshold and the measured external dimensions exceed a preset external dimension threshold. When the control device 80 determines that the cast member 1 is unsuitable, the cast member 1 being transported is removed from the transport path by the transport device and transferred to the unsuitable product storage area.
[0046] Furthermore, each threshold can be set arbitrarily based on the results of experiments, for example, and stored in memory. The external dimension threshold and surface temperature threshold are reference values for determining whether the molded cast member 1 is suitable to be joined with the joining member 2.
[0047] In the joining process, at least a portion of the identified joining member 2 is joined to the cast member 1. In the joining process, a portion of the joining member 2 having the hardness indicated by the hardness information selected in the joining member identification process is inserted into the hole 10 of the cast member 1 using an insertion device. This allows the joining member 2 to be joined to the cast member 1.
[0048] In this embodiment, as shown in Figure 1, the remaining portion of the joining member 2 that protrudes from the cast member 1 after insertion is inserted into the hole 10 of the mating cast member 3. This allows the joining member 2 to be joined to the mating cast member 3. The mating cast member 3 has the same structure as the cast member 1, and is formed using a die-casting apparatus different from the die-casting apparatus 100 used for the cast member 1. However, the mating cast member 3 may be made of a non-ferrous metal composed of the same or similar type of metallic material as the cast member 1.
[0049] Here, the cast member 1 and the mating cast member 3 undergo dimensional deformation due to shrinkage caused by cooling, resulting in a reduction in the diameter of the hole 10 in each. Therefore, by cooling the cast member 1 and the mating cast member 3 with the joining member 2 inserted, the cast member 1, the mating cast member 3, and the joining member 2 can be completely joined. This cooling can be, for example, natural cooling. Through the above steps, a joined product 4 of dissimilar metal members can be obtained by joining the cast member 1 and the mating cast member 3 via the joining member 2.
[0050] In the method for joining dissimilar metal members according to this embodiment, before joining the joining member 2 to the cast member 1, the joining member 2 having an appropriate hardness for the state of the molded cast member 1 can be identified based on the results of measuring the external dimensions and surface temperature of the cast member 1, respectively. This prevents the joining member 2 from falling off the cast member 1 due to dimensional deformation caused by cooling when the joining member 2 is joined to the cast member 1. Therefore, the method for joining dissimilar metal members according to this embodiment makes it possible to join dissimilar metal members with high bonding strength.
[0051] This disclosure is not limited to the embodiments described above, and can be modified as appropriate without departing from the spirit of the invention. For example, in the above embodiment, the control device 80 performed the joining member identification process based on the external dimensions and surface temperature of the cast product measured within a predetermined time after the cast member 1 was removed from the mold 20, but the configuration is not limited to this. The control device 80 may also perform the joining member identification process based on the external dimensions of the cast member 1 inside the mold 20 and the surface temperature of the mold 20 measured within a predetermined time after the mold 20 was opened. In other words, the dimension measurement process, temperature measurement process, and joining member identification process may be performed after the mold opening process and before the removal process. In this case, the imaging camera 60 is positioned to be able to photograph the cast member 1 inside the mold 20. The thermal camera 71 is positioned to be able to detect infrared light emitted from the mold 20.
[0052] Furthermore, at least one of the imaging camera 60 and the thermoviewer 70 may have an image processing function in the control device 80.
[0053] Furthermore, to measure the external dimensions of the cast member 1, a non-contact sensor such as a laser displacement sensor may be used instead of the camera 60. To measure the surface temperature of the cast member 1, a non-contact sensor such as a radiation temperature sensor may be used instead of the thermal camera 71 and thermal viewer 70. Also, when measuring the surface temperature of the mold 20, a contact-type temperature sensor may be placed on the mold 20 instead of a non-contact sensor. [Explanation of Symbols]
[0054] 1. Cast member 2. Joining member 3. Mating cast member 4. Joined product 10. Hole 20 Mold 21 Fixed mold 22 Movable mold 23 Casting pin 30 Cavity 31 Gate 32 Runner 41 Injection sleeve 42 Plunger tip 43 Rod 44 Hot water inlet 51 Pressure reducing passage 52 Pressure reducing valve 60 Imaging camera 70 Thermal viewer 71 Thermal camera 80 Control device 100 die casting equipment
Claims
[Claim 1] The casting process involves shaping cast components using a mold, A dimensional measurement step for measuring the external dimensions of the cast member inside the mold or the cast member removed from the mold, A temperature measurement step for measuring the surface temperature of the mold or the casting member, A joining member identification step involves identifying a joining member having a hardness determined based on the external dimensions and surface temperature measured within a predetermined time after the mold is opened or after the cast member is removed from the mold, respectively. A joining step of inserting at least a portion of the identified joining member into the hole of the cast member and joining them, It has, A method for joining dissimilar metal members, wherein the joining member is made of a different metal material having a lower coefficient of thermal expansion than the metal material constituting the cast member.