Method for joining dissimilar metal member

Abstract

To provide a method for joining dissimilar metal members, capable of joining the dissimilar metal members with high joint strength.SOLUTION: A method for joining dissimilar metal members includes: a casting step of forming a casting member using a metal mold; a dimension-measuring step of measuring an external dimension of a casting member in a metal mold or a casting member taken out from inside a metal mold; a temperature-measuring step of measuring the surface temperature of the metal mold or the casting member; a joining member-identifying step of identifying a joining member having a hardness determined based on the external dimension and the surface temperature measured within a predetermined time after the mold is opened or after the casting member is taken out from inside the mold, after the casting member is formed; and a joining step of joining at least a portion of the identified joining member to the casting member. The joining member is composed of a metal material having a lower coefficient of thermal expansion than that of the metal material constituting the casting member.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a method for joining dissimilar metal members. [Background technology]

[0002] For example, when connecting dissimilar metal members, such as a non-ferrous metal member and a ferrous metal (steel) member, directly joining the two members by welding or the like generates brittle intermetallic compounds at the joining interface. As a result, the joint strength varies widely and the reliability of the joint decreases. Therefore, a method is known in which a cast product is produced by integrating the ferrous metal member and the non-ferrous metal member into one piece, and then the cast product is joined to another member.

[0003] Patent Document 1 discloses a cast product to be joined to a mating member, which is characterized by comprising: a plurality of joining tips that are joined to a plurality of locations on the mating member at the respective joining surfaces of the joining tips; and a cast metal material that is made of a different metal material from the mating member and that casts in the mating member while dispersing the plurality of joining tips and exposing at least one joining surface of each of the joining tips.

[0004] According to the technology described in Patent Document 1, multiple joining tips dispersed and cast into the cast metal material are joined to multiple locations of the mating member, so the size of the joining tips can be reduced. As a result, it is described that the stress generated in the cast metal material due to contraction caused by cooling of the cast metal material can be suppressed. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2015-186824 A Summary of the Invention [Problem to be solved by the invention]

[0006] When a cast member (cast metal material) is molded using a metal mold, the temperature of the cast member obtained immediately after the metal mold is opened changes over time. When joining dissimilar metal members, such as a non-ferrous cast member and a joining member made of an iron-based metal, there is a problem in that the dimensional deformation of the cast member due to temperature change reduces the joining strength between the dissimilar metal members.

[0007] The present disclosure has been made to solve such problems, and has an object to provide a method for joining dissimilar metal members that can join dissimilar metal members with high joining strength. [Means for solving the problem]

[0008] A method for joining dissimilar metal components in one embodiment includes a casting process for molding a cast component using a mold, a dimension measurement process for measuring the outer dimensions of the cast component in the mold or the cast component removed from the mold, a temperature measurement process for measuring the surface temperature of the mold or the cast component, a joining member identification process for identifying a joining member having a hardness determined based on the outer dimensions and surface temperature measured within a predetermined time after the mold is opened or after the cast component is removed from the mold after molding the cast component, and a joining process for joining at least a portion of the identified joining member to the cast component, wherein the joining member is made of a dissimilar metal material having a lower thermal expansion coefficient than the metal material constituting the cast component. Effect of the Invention

[0009] The present disclosure makes it possible to provide a method for joining dissimilar metal members, which can join dissimilar metal members with high joining strength. [Brief description of the drawings]

[0010] [Figure 1] 1A to 1C are diagrams illustrating a method for joining dissimilar metal members according to a first embodiment. [Diagram 2] 3 is a flowchart showing a method for joining dissimilar metal members according to the first embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] First embodiment Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. However, the present disclosure is not limited to the following embodiments. In addition, the following description and drawings are appropriately simplified for clarity of explanation.

[0012] First, Fig. 1 is a diagram for explaining a method for joining dissimilar metal members according to embodiment 1. As shown in Fig. 1, in the method for joining dissimilar metal members according to this embodiment, a joining member 2 is joined to a cast member 1 by utilizing a difference in thermal expansion between the cast member 1 and a joining member 2 made of a different metal material.

[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 part of the joining member 2 is inserted.

[0014] The joining member 2 is made of a different metal material having a lower thermal expansion coefficient than the metal material constituting the cast member 1. The joining member 2 is made of an iron-based metal including iron, such as various alloy steels and 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, by using a die-casting apparatus 100 shown in Fig. 1. The die-casting apparatus 100 is an apparatus for manufacturing the cast member 1 corresponding to the shape of the cavity 30 by die casting, in which a high-temperature molten metal made of molten aluminum or the like is filled into a cavity 30 formed by a die 20, and the molten metal is then cooled and solidified.

[0016] The die-casting apparatus 100 includes a mold 20 that forms a cavity 30, an injection device that injects molten metal into the cavity 30, a clamping device that opens and closes the mold 20 and clamps it, a pressure reducing device that supplies negative pressure into the cavity 30, and a conveying device that removes the cast part 1 from the mold 20.

[0017] The mold 20 has a fixed mold 21, a movable mold 22 that can be closed and opened by moving relative to the fixed mold 21, and a core pin 23 attached to the movable mold 22. The mold 20 forms a cavity 30 corresponding to the shape of the cast member 1 between the fixed mold 21 and the movable mold 22 by clamping the fixed mold 21 and the movable mold 22 together. A gate 31 and a runner 32 are further formed in the clamped mold 20. The core pin 23 is a core die that forms a core hole as the hole portion 10 in the cast member 1. The core pin 23 has, for example, a cylindrical shape. The tip portion of the core pin 23 protrudes into the cavity 30. The core pin 23 may be attached to the fixed mold 21.

[0018] The injection device has an injection sleeve 41, a plunger tip 42, a rod 43, and a plunger drive means. The injection sleeve 41 communicates with the runner 32 and is connected to the fixed mold 21. A molten metal supply port 44 for pouring molten metal into the injection sleeve 41 is formed at the rear end of the injection sleeve 41. The plunger tip 42 is disposed in the injection sleeve 41 so as to be movable forward and backward within the injection sleeve 41 along the longitudinal direction of the injection sleeve 41. The plunger drive means drives the plunger tip 42 forward and backward via a rod 43 connected to the plunger tip 42.

[0019] Movable die 22 is provided with a pressure reducing valve 52 via a pressure reducing passage 51 whose one end opens into cavity 30. A pressure reducing device including a vacuum pump is connected to pressure reducing valve 52. Die casting apparatus 100 is configured such that, when pressure reducing valve 52 is opened, negative pressure is supplied from the pressure reducing device into cavity 30.

[0020] The clamping device moves the movable die plate, to which the movable die 22 is fixed, relative to the fixed die plate, to which the fixed die 21 is fixed, by the driving force of the clamping drive means. In this way, the clamping device closes and opens the die 20 to open and close it, and clamps the die 20.

[0021] The transfer device removes the cast member 1 from within the die 20 to the outside of the die 20, and then transfers the removed cast member 1 along a transfer path outside the die 20. As the transfer device, for example, a robot arm having an arm for gripping the cast member 1 can be used.

[0022] Furthermore, the die-casting apparatus 100 has a camera 60 for photographing the cast member 1 removed from the mold 20, a thermoviewer 70 for measuring the surface temperature of the cast member 1 removed from the mold 20, and a control device 80 for controlling the operation of the die-casting apparatus 100.

[0023] The photographing camera 60 may be, for example, a two-dimensional camera that captures two-dimensional images, or a three-dimensional camera that captures three-dimensional images. The photographing camera 60 is provided above the transport path. The photographing camera 60 is provided at a position where it can capture an image of the cast member 1 within a predetermined time (for example, within 10 seconds) after the cast member 1 is removed from the mold 20. The photographing camera 60 transmits image data of the captured image of the cast member 1 to the control device 80.

[0024] The thermoviewer 70 generates two-dimensional temperature distribution image data from image data captured by a thermocamera 71 connected wirelessly or by wire. The thermocamera 71 is provided above the transport path in line with the image capture camera 60. The thermocamera 71 is provided in a position capable of detecting infrared light emitted from the cast component 1 within a predetermined time (e.g., within 10 seconds) after the cast component 1 is removed from the mold 20. The thermoviewer 70 generates image data of a temperature distribution image showing the distribution of the surface temperature of the cast component 1 based on the image data captured by the thermocamera 71. 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 the thermoviewer 70. By having an image measuring device such as the thermoviewer 70 or a thermograph, the die casting apparatus 100 can measure the temperature of the cast member 1 precisely.

[0026] Here, the predetermined time from when the cast member 1 is removed from the mold 20 until when it is photographed is set according to the size of the cast member 1, etc. The predetermined time from when the cast member 1 is removed from the mold 20 until when it is photographed can be, for example, 30 seconds when the temperature of the cast member 1 immediately after removal is 200 to 300°C.

[0027] The control device 80 is composed of a computer equipped with a processor that executes various calculations, memories such as a ROM (Read Only Memory) and a RAM (Random Access Memory), an input / output interface, etc. The control device 80 functions as a die-casting control unit that controls the operations of the injection device, the mold clamping device, the pressure reducing device, the transport device, etc., by the processor executing 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 programs, the memory stores multiple types of hardness information, a surface temperature threshold, an external dimension threshold, etc.

[0028] The control device 80 is connected to each of the injection device, the mold clamping device, the pressure reduction device, the transport device, etc. via control lines. The control device 80 controls the operation of each of the injection device, the mold clamping device, the pressure reduction device, the transport device, etc. by supplying control signals to each of the injection device, the mold clamping device, the pressure reduction device, the transport device, etc. via the control lines. The control device 80 is also connected to each of the photographing camera 60 and the thermoviewer 70 via detection signal lines. The control device 80 detects the state of the cast member 1 from detection signals supplied from each of the photographing camera 60 and the thermoviewer 70 via the detection signal lines.

[0029] An input device operated by an operator, a display device for displaying various values, etc. may be connected to the control device 80. Note that some or all of the functions of each part of the die casting apparatus 100 may be realized by a hardware circuit.

[0030] The die casting apparatus 100 molds the cast member 1 with the die 20 closed under the control of the control device 80, and then removes and transports the cast member 1 by the transport device with the die 20 open. Thereafter, the die casting apparatus 100 detects the condition of the molded cast member 1 by the photographing camera 60 and the thermo camera 71.

[0031] The control device 80 analyzes the image data received from the photographing camera 60 and the thermoviewer 70. The control device 80 measures the outer dimensions of the cast member 1 based on the image data received from the photographing camera 60. 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 or not the cast member 1 is suitable to be joined to the joining member 2 based on the measured surface temperature and outer dimensions. If the control device 80 determines that the cast member 1 is suitable, it may identify the joining member 2, which will be 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 during transport.

[0033] The control device 80 identifies the joining member 2 having a hardness determined based on the measured surface temperature and outer dimensions. The control device 80 determines the hardness of the joining material by referring to the hardness information stored in the memory. The control device 80 selects hardness information corresponding to the combination of the surface temperature and outer dimensions from the multiple types of hardness information stored in the memory.

[0034] Then, the control device 80 controls the transport device to set the cast member 1 in a suitable storage area where the joining member 2 will be joined. 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 manner, the control device 80 controls the joining of at least a portion of the identified joining member 2 to the cast member 1.

[0035] An example of the method for joining dissimilar metal members according to this embodiment will be described with reference to Fig. 2 in addition to Fig. 1. Fig. 2 is a flowchart showing the method for joining dissimilar metal members according to embodiment 1. As shown in Fig. 2, the method for joining dissimilar metal members according to this embodiment includes steps S1 to S5.

[0036] In the casting process, the cast member 1 is molded using a mold 20 (step S1). The casting process includes, for example, a mold clamping process, a molten metal pouring process, an injection and 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 molten metal pouring process, a predetermined amount of molten metal is poured into the injection sleeve 41 from the molten metal supply port 44 (step S1-2). When the molten metal is molten 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 molten metal in the injection sleeve 41 into the cavity 30 of the mold 20 (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 in 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 the molten metal at a high speed. By performing the low-speed injection process, the entrainment of air is suppressed, and the filling rate of the molten metal is increased. By performing the high-speed injection process, the molten metal can 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 (step S1-4). This allows the molding of a cast member 1 corresponding to the shape of the cavity 30. In the cast member 1 thus molded, a hole 10 is formed by a core pin 23. In the solidification process, the molten metal is cooled to a temperature (e.g., about 200°C) at which the cast member 1 can be removed.

[0040] Next, in the mold opening process, after the cast member 1 is molded 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 transport device (step S1-6). The cast member 1 is then transported to a subsequent process by the transport device. The cast member 1 removed from the mold 20 is quickly transported by the transport device to the imaging area of ​​the photographing camera 60 and the detection area of ​​the thermo camera 71.

[0041] In the dimension measurement process, the photographing camera 60 acquires image data of an image of the cast member 1 taken within a predetermined time after it is removed from the mold 20. Then, in the dimension measurement process, the control device 80 measures the external dimensions of the cast member 1 based on the image data of the image taken by the photographing camera 60 (Step S2).

[0042] In the temperature measurement process, the thermo camera 71 detects infrared light emitted from the cast member 1 within a predetermined time after it is 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 image data of a temperature distribution image generated by the thermo viewer 70 from the photographing data taken by the thermo camera 71 (step S3).

[0043] In the joining member identification process, it is determined whether or not the cast member 1 is suitable to be joined to the joining member 2 based on the surface temperature and outer dimensions measured within a predetermined time. The control device 80 determines that the cast member 1 is suitable if the measured surface temperature is equal to or lower than a preset surface temperature threshold and the measured outer dimensions are equal to or lower than a preset outer dimension threshold. If the control device 80 determines that the cast member 1 is suitable, it proceeds to identifying the joining member 2.

[0044] In the joining member identification process, a joining member 2 having a hardness determined based on the outer 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 either "highest hardness", "slightly high 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 the surface temperature and the outer dimensions. The hardness information indicates a correlation such that, for example, the harder the cast member 1 is, the larger the outer dimensions and the surface temperature are, respectively.

[0045] On the other hand, if the measured surface temperature exceeds a preset surface temperature threshold and the measured outer dimensions exceed a preset outer dimension threshold, the control device 80 determines that the cast member 1 is unqualified. If the control device 80 determines that the cast member 1 is unqualified, the conveying device removes the cast member 1 from the conveying path during conveying and transfers it to a unqualified item storage area.

[0046] For example, each threshold value may be set arbitrarily based on the results of experiments or the like and stored in memory. The threshold values ​​of the outer dimension and the surface temperature are reference values ​​for determining whether the molded cast member 1 is suitable as the cast member 1 to be joined to the joining member 2.

[0047] In the joining step, at least a portion of the identified joining member 2 is joined to the cast member 1. In the joining step, a portion of the joining member 2 having a hardness indicated by the hardness information selected in the joining member identifying step 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] 1, the remaining part of the joining member 2 protruding from the cast member 1 after the joining member 2 is inserted is inserted into a 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 a similar structure to the cast member 1 and is molded using a die-casting device 100 different from the die-casting device 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 type or family of metallic material as the cast member 1.

[0049] Here, the cast member 1 and the mating cast member 3 undergo dimensional deformation in which the diameter of the hole 10 decreases due to contraction associated with cooling. Therefore, by cooling the cast member 1 and the mating cast member 3 into which the joining member 2 has been inserted, the cast member 1, the mating cast member 3, and the joining member 2 can be completely joined. The cooling at this time may be, for example, natural cooling. Through the above steps, a joined product 4 of dissimilar metal members can be obtained in which the cast member 1 and the mating cast member 3 are joined via the joining member 2.

[0050] In the method for joining dissimilar metal members according to the present embodiment, before joining the joining member 2 to the cast member 1, the outer dimensions and surface temperature of the cast member 1 are measured, and the joining member 2 having an appropriate hardness for the state of the molded cast member 1 can be specified based on the results. 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, according to the method for joining dissimilar metal members according to the present embodiment, dissimilar metal members can be joined together with high joining strength.

[0051] The present disclosure is not limited to the above embodiment, and can be modified as appropriate without departing from the spirit of the present disclosure. For example, in the above embodiment, the control device 80 performs the joining member specifying step based on the outer dimensions and surface temperature of the cast product measured within a predetermined time after the casting member 1 is removed from the die 20, but the present disclosure is not limited to such a configuration. The control device 80 may perform the joining member specifying step based on the outer dimensions of the cast member 1 in the die 20 and the surface temperature of the die 20 measured within a predetermined time after the die 20 is opened. That is, the dimension measuring step, the temperature measuring step, and the joining member specifying step may be performed after the die opening step and before the removal step. In this case, the photographing camera 60 is provided at a position where the casting member 1 in the die 20 can be photographed. The thermo camera 71 is provided at a position where the infrared light emitted from the die 20 can be detected.

[0052] At least one of the photographing 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 photographic 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 thermo camera 71 and the thermoviewer 70. To measure the surface temperature of the mold 20, a contact temperature sensor may be disposed on the mold 20 instead of a non-contact sensor. [Explanation of symbols]

[0054] 1 Cast member 2 Joining member 3 Counterpart 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 supply port 51 Pressure reducing passage 52 Pressure reducing valve 60 Shooting camera 70 Thermoviewer 71 Thermocamera 80 Control device 100 Die casting equipment

Claims

[Claim 1] a casting process for forming a cast member using a metal mold; a dimension measuring step of measuring an outer dimension of the cast member in the mold or the cast member removed from the mold; a temperature measuring step of measuring a surface temperature of the mold or the cast member; a joining member specifying step of specifying a joining member having a hardness determined based on the outer dimensions and the surface temperature measured within a predetermined time after the mold is opened or the cast member is removed from the mold after molding the cast member; a joining step of joining at least a part of the identified joining member to the cast member; having The method for joining dissimilar metal members, wherein the joining member is made of a different metal material having a lower thermal expansion coefficient than the metal material constituting the cast member.

Images