Joint structure separation method and joint structure

Abstract

A joint structure separation method for separating a joint structure (11) into a first material (1) and a second material (2), the joint structure separation method comprising: a step of bringing a cutting element (24) into contact with a joint surface (3) between the first material (1) and the second material (2) from a heating body (21) side while an external stimulus is supplied to the heating body (21), the cutting element (24) including the heating body (21) that generates heat upon receiving supply of the external stimulus, a cooling body (23) that moves while maintaining a relative positional relationship with the heating body (21) and cools the first material, and a heat insulating body (22) disposed between the heating body (21) and the cooling body (23) and moving while maintaining a relative positional relationship with each of the heating body (21) and the cooling body (23); and a step of separating the first material (1) and the second material (2) by moving the cutting element (24) in an advancing direction in which the heating body (21) side is a front side.

Description

Method for Separating Joined Structure and Joined Structure

[0001] The present disclosure relates to a method for separating a joined structure formed of a first material made of thermoplastic plastic and a second material of any material, and to the joined structure.

[0002] For example, regarding members used in processing machines and the like, there is a movement toward using joined structures obtained by joining dissimilar materials from the viewpoint of weight reduction and the like. On the other hand, in recent years, in order to reuse each constituent member of the joined structure after use, development of techniques for separating and disassembling the joint portion of each constituent member has been promoted.

[0003] Patent Document 1 discloses a member peeling device including a heating wire and a cooling wire, as a device for separating a member in which one of the constituent members is an adhesive layer having thermoplasticity. In the technology disclosed in Patent Document 1, after a thermoplastic material is heated and cut by the heating wire, the cut portion is immediately cooled by the cooling wire, so that the member can be separated and disassembled while suppressing re-welding of the thermoplastic material.

[0004] Japanese Unexamined Patent Application Publication No. 2016-128193

[0005] However, the technology disclosed in Patent Document 1 has a problem in that heat is transferred from the heating wire to the cooling wire, so as cutting progresses, the cooling wire stops functioning, making stable separation and disassembly impossible.

[0006] The present disclosure has been made in view of the foregoing, and an object thereof is to obtain a method for separating a joined structure that enables stable separation and disassembly of a joined structure containing thermoplastic plastic.

[0007] To solve the above-mentioned problems and achieve the objective, the method for separating a bonded structure according to the present disclosure is a method for separating a bonded structure having a first material including a thermoplastic and a second material bonded to the first material into a first material and a second material. The method for separating a bonded structure comprises a step of bringing a cutting element, which includes a heating element that generates heat when an external stimulus is supplied, a cooling element that moves while maintaining its relative positional relationship with the heating element to cool the first material, and an insulating element that is placed between the heating element and the cooling element and moves while maintaining its relative positional relationship with each of the heating element and the cooling element, into contact with the bonded surface between the first material and the second material from the heating element side while an external stimulus is supplied to the heating element, and a step of moving the cutting element in a direction of travel with the heating element side facing forward to separate the first material and the second material.

[0008] This disclosure provides the advantage of obtaining a method for separating bonded structures that can stably separate and dismantle bonded structures containing thermoplastic plastics.

[0009] A perspective view showing an example of a joint structure separation method according to Embodiment 1. A top view showing an example of a joint structure separation method according to Embodiment 1. A top view showing an example of a joint structure separation method according to Embodiment 2. A cross-sectional view showing an example of a joint structure separation method according to Embodiment 2. A top view showing an example of a joint structure separation method according to Embodiment 3. A top view showing an example of a joint structure according to Embodiment 4. A cross-sectional view of a joint structure according to Embodiment 4. A top view showing another example of a joint structure according to Embodiment 4. A top view showing yet another example of a joint structure according to Embodiment 4. A top view showing an example of a joint structure according to Embodiment 5. A cross-sectional view of a joint structure according to Embodiment 5.

[0010] The joint structure separation method and the joint structure according to the embodiment will be described in detail below with reference to the drawings.

[0011] Embodiment 1. Figure 1 is a perspective view showing an example of a method for separating a joined structure according to Embodiment 1. The method for separating a joined structure according to Embodiment 1 is a method for separating a joined structure 11 consisting of a first material 1 made of thermoplastic plastic and a second material 2 of any material. The first material 1 and the second material 2 are joined at a joint surface 3.

[0012] A heating element 21, an insulating element 22, and a cooling element 23 are used to separate the joint structure 11. The heating element 21 generates heat upon receiving an external stimulus called a trigger. The insulating element 22 is positioned between the heating element 21 and the cooling element 23 to suppress the exchange of heat between the heating element 21 and the cooling element 23. The insulating element 22 is positioned in contact with or without contact with the heating element 21. Similarly, the cooling element 23 is positioned in contact with or without contact with the insulating element 22. That is, the insulating element 22 may be positioned in contact with each of the heating element 21 and the cooling element 23, or without contact, or in contact with only one of them. Furthermore, the insulating element 22 and the cooling element 23 move while maintaining their relative positional relationship with the heating element 21. In the following description, the heating element 21, the insulating element 22, and the cooling element 23 are collectively referred to as the cutting element 24.

[0013] As shown in Figure 1, the heating element 21 of the cutting element 24, while heated, comes into contact with the joining surface 3, melting the thermoplastic plastic of the first material 1 at the joining surface 3. Subsequently, by moving the cutting element 24 across the entire surface of the joining surface 3, the joined structure 11 is separated and dismantled into the first material 1 and the second material 2.

[0014] The method for separating the joined structure will be described in detail below with specific examples. Figure 2 is a top view showing an example of the method for separating the joined structure according to Embodiment 1. The first material 1 can be any material that includes a thermoplastic such as nylon 6 resin as a component. The second material 2 can be any material different from the first material 1, but for example, an aluminum alloy can be used. The surface of the second material 2 may be treated to improve its bonding properties with the thermoplastic. For example, laser treatment or blast treatment can be used as the surface treatment.

[0015] For the heating element 21, for example, a nichrome wire can be used. Nichrome wire has high electrical resistance and generates heat when it conducts electricity. Therefore, electricity can be used as a trigger. For the insulating element 22, for example, a bundle of glass fibers can be used. For the cooling element 23, for example, an aluminum wire can be used.

[0016] The heating element 21, the insulating element 22, and the cooling element 23 are arranged so that they move relative to each other. Figure 2 shows an example where the heating element 21, the insulating element 22, and the cooling element 23 are arranged in parallel, and the joining structure 11 is being cut.

[0017] When an electric current is applied from the power supply 31 to the nichrome wire, which is the heating element 21, the nichrome wire generates heat. When the nichrome wire is brought into contact with the joint surface 3 of the joint structure 11, which consists of the first material 1 and the second material 2, from the end face of the joint structure 11 while the nichrome wire is heated, the nylon 6, which is the first material 1, melts, and the area where the heating element 21 made contact can be separated into the first material 1 and the second material 2. After the heating element 21 has passed through a part of the joint surface 3, the insulating element 22 and the cooling element 23 follow the movement of the heating element 21 and pass through the separated area of ​​the joint surface 3 in this order. At this time, the cooling element 23 removes the heat remaining in the first material 1, so the first material 1 can be cooled and solidified quickly. This prevents the first material 1 from coming into contact with the second material 2 in a molten state and re-fusing. On the other hand, since the insulating body 22 is located between the heating body 21 and the cooling body 23, it suppresses the direct conduction of heat from the heating body 21 to the cooling body 23, thereby maintaining the cooling effect of the cooling body 23. The cutting element 24 crosses the entire joint surface 3 of the joint structure 11, allowing the joint structure 11 to be completely separated and dismantled into the first material 1 and the second material 2.

[0018] Although the description has described a configuration in which the joint structure 11, consisting of the first material 1 and the second material 2, is separated at its joint surface 3, the first material 1 may also be cut and separated from the inside.

[0019] Furthermore, although the joint structure 11 has been described as consisting of a first material 1 and a second material 2, it may also be configured in which another material is located between the first material 1 and the second material 2. For example, the joint structure 11 may have an adhesive layer or the like provided between the first material 1 and the second material 2.

[0020] Furthermore, the target of separation can also be a joint structure 11 having a third material of any material different from the second material 2 on the surface of the first material 1 opposite to the surface that joins with the second material 2. In this case, the joint structure 11 can be cut and separated by the cutting element 24 passing through either the interior of the first material 1 made of thermoplastic plastic, the joining surface 3 with the second material 2, or the joining surface between the first material 1 and the third material.

[0021] Furthermore, although a configuration for separating the planar joint structure 11 has been described, the joint structure 11 is not limited to a planar shape. It can be any shape, such as a two-dimensional curved surface, a shape having both a planar and a curved surface, or a shape having a three-dimensional curved surface.

[0022] Furthermore, while the use of nylon 6 resin as the first material 1 has been described, any thermoplastic can be used. Specifically, polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, polycarbonate, polystyrene, ABS (Acrylonitrile Butadiene Styrene), nylon 6, nylon 66, nylon 11, nylon 12, polyphenylene sulfide, polyetherimide, polyimide, polyetherketone, polyetheretherketone, polyaryleneetherketone, etc. can be used. Moreover, the material constituting the first material 1 does not have to be a thermoplastic alone, and may include a reinforcing material. Examples of reinforcing materials include inorganic fillers, carbon fibers, glass fibers, etc. In the case of fiber reinforcement, the fibers may be short fibers, long fibers, or continuous fibers. Thus, the first material 1 can be a fiber-reinforced plastic with a thermoplastic as the base material.

[0023] Furthermore, although the case where the heating element 21, the insulating element 22, and the cooling element 23 are linear has been described, they can be any shape. In addition, the cross-sectional shape of the heating element 21, the insulating element 22, and the cooling element 23 can be any shape such as circular, rectangular, or elliptical.

[0024] Furthermore, although the use of nichrome wire as the heating element 21 has been described, titanium, stainless steel, carbon fiber, etc. may also be used as the heating element 21. The electrical resistance of the heating element 21 is preferably 0.5 μΩ·m or more and 10 μΩ·m or less. By setting the electrical resistance of the heating element 21 to 0.5 μΩ·m or more and 10 μΩ·m or less, the amount of heat generated in the heating element 21 when electricity is passed through it can be set to an amount of heat that is able to melt the first material 1 without causing deformation of the first material 1. Moreover, the trigger supplied to the heating element 21 is not limited to electricity, and a method of directly applying heat to the heating element 21 by heat conduction from a heat source such as a heater may also be used.

[0025] Furthermore, although the use of a glass fiber bundle as the heat insulating body 22 has been described, foam material, metal wire, plastic wire, etc. may be appropriately selected and used for the heat insulating body 22. When using metal wire for the heat insulating body 22, it is preferable to apply an insulating coating to insulate it from the heating element 21 in order to avoid heat generation due to the current flowing from the heating element 21. In addition, an insulating wire may be placed between the heating element 21 and the heat insulating body 22 to avoid heat generation due to the current flowing from the heating element 21.

[0026] Furthermore, although the use of aluminum wire as the cooler 23 has been described, silver, copper, or carbon fiber may also be used. A material with high thermal conductivity and specific heat is preferred for the cooler 23. Additionally, a component utilizing the Peltier effect can also be used as the cooler 23. When using a component utilizing the Peltier effect as the cooler 23, an electric current is applied to the cooler 23 when the joint structure 11 is cut to activate the Peltier effect. It is also preferable that the electrical resistance of the cooler 23 is smaller than that of the heating element 21. By having a lower electrical resistance for the cooler 23 than that of the heating element 21, the heat generated by the current flowing through the cooler 23 can be suppressed from hindering the cooling of the first material 1 by the Peltier effect.

[0027] As described above, the method for separating a joined structure according to Embodiment 1 includes the step of bringing a cutting element 24, which comprises a heating element 21 that generates heat when an external stimulus is supplied, a cooling element 23 that moves while maintaining its relative positional relationship with the heating element 21 to cool the first material 1, and a heat insulating element 22 that is positioned between the heating element 21 and the cooling element 23 and moves while maintaining its relative positional relationship with each of the heating element 21 and the cooling element 23, into contact with the joining surface 3 of the first material 1 and the second material 2 from the heating element 21 side while an external stimulus is supplied to the heating element 21. Furthermore, the method for separating a joined structure according to Embodiment 1 includes the step of moving the cutting element 24 in a direction of travel with the heating element 21 side facing forward to separate the first material 1 and the second material 2. The method for separating a joined structure according to Embodiment 1 uses a cutting element 24 consisting of a heating element 21, an insulating element 22, and a cooling element 23. When the cutting element 24 is pressed against the joint surface 3 of a joined structure 11 consisting of a first material 1 made of thermoplastic plastic and a second material 2 of any material, the heating element 21 melts the first material 1, and the cooling element 23 further suppresses heat accumulation in the first material 1, so the first material 1 and the second material 2 can be separated and dismantled without re-fusion. The insulating element 22 suppresses the exchange of heat between the heating element 21 and the cooling element 23, so the cooling effect of the cooling element 23 can be maintained.

[0028] Embodiment 2. Figure 3 is a top view showing an example of a joint structure separation method according to Embodiment 2. Figure 4 is a cross-sectional view showing an example of a joint structure separation method according to Embodiment 2. Figure 4 shows a cross-section along the line IV-IV in Figure 3. The joint structure separation method according to Embodiment 2 uses a cutting element 24 in which a heating element 21, an insulating element 22, and a cooling element 23 are integrated by a connecting member 25. As shown in Figure 4, of the cutting element 24 integrated by the connecting member 25, the heating element 21 first comes into contact with the joint surface 3 between the first material 1 and the second material 2 while heated, melting the thermoplastic plastic of the first material 1. From this state, the cutting element 24 moves along the joint surface 3, separating and dismantling the first material 1 and the second material 2. Parts of each of the heating element 21 and the cooling element 23 are exposed and not covered by the connecting member 25. Therefore, when the joint structure 11 is separated and disassembled, a portion of each of the heating element 21 and the cooling element 23 comes into direct contact with the first material 1. As a result, heat transfer from the heating element 21 to the first material 1 and heat transfer from the first material 1 to the cooling element 23 are not hindered by the connecting member 25, ensuring that the melting and cooling of the first material 1 can be reliably performed. Alternatively, a portion of either the heating element 21 or the cooling element 23 may be exposed without being covered by the connecting member 25. In this case, it is possible to ensure that either heat transfer from the heating element 21 to the first material 1 or heat transfer from the first material 1 to the cooling element 23 is not hindered by the connecting member 25.

[0029] The method for separating the joined structures will be explained in detail below with specific examples. As shown in Figure 4, the heating element 21 and the insulating element 22, and the insulating element 22 and the cooling element 23 are in contact in part. For the connecting member 25, for example, glass fiber reinforced plastic can be used. The cross-sectional shape of the connecting member 25 can be, for example, trapezoidal. The connecting member 25 and the heating element 21, insulating element 22, and cooling element 23 can be joined by adhesive, for example. Alternatively, a filling material 26 may be used to fill the gaps between the heating element 21, insulating element 22, and cooling element 23. As the material for the filling material 26, for example, the adhesive used to bond the connecting member 25 to the heating element 21, insulating element 22, and cooling element 23 can be used. Part of the heating element 21, part of the cooling element 23, or both are not covered by the connecting member 25 and are configured to be in direct contact with the joined structure 11. By moving the cutting element 24, which is integrated by the connecting member 25, along the joint surface 3 of the first material 1 and the second material 2 in the order of the heating element 21, the insulating element 22, and the cooling element 23, the first material 1 and the second material 2 can be separated and disassembled. By using the cutting element 24 integrated by the connecting member 25, the relative positional relationship of the heating element 21, the insulating element 22, and the cooling element 23 can be reliably maintained, and the scattering of the heating element 21, the insulating element 22, and the cooling element 23 when the joint structure 11 is cut can be suppressed.

[0030] Although a configuration has been described in which the heating element 21 and the insulating element 22 are in contact in part, and the insulating element 22 and the cooling element 23 are in contact in part, the insulating element 22 does not necessarily have to be in contact with at least one of the heating element 21 and the cooling element 23.

[0031] Furthermore, although the use of glass fiber reinforced plastic as the material for the connecting member 25 has been described, any material such as metal, ceramic, and plastic may be used. The material for the connecting member 25 is preferably a ceramic or plastic material with low thermal conductivity in order to suppress the exchange of heat between the heating element 21 and the cooling element 23.

[0032] Furthermore, although the case where the cross-sectional shape of the connecting member 25 is trapezoidal has been described, it is sufficient that the cutting element 24 can be integrated, and the cross-sectional shape of the connecting member 25 may be any cross-sectional shape, such as a rectangle or a semi-ellipse. Preferably, the thickness of each of the upper and lower connecting members 25 is 1 / 2 or less of the thickness of the thickest of the heating element 21, the insulating element 22, and the cooling element 23.

[0033] Furthermore, although a configuration in which the connecting member 25 is arranged to sandwich the heating element 21, the insulating element 22, and the cooling element 23 has been described, it is sufficient if the heating element 21, the insulating element 22, and the cooling element 23 can be integrated, and a configuration in which the connecting member 25 is arranged to contact the heating element 21, the insulating element 22, and the cooling element 23 from one direction is also acceptable.

[0034] Furthermore, although a configuration in which one connecting member 25 spans the heating element 21, the insulating element 22, and the cooling element 23 has been described, it is also possible for the heating element 21 and the insulating element 22, and the insulating element 22 and the cooling element 23 to be integrated by separate connecting members 25.

[0035] Furthermore, although a configuration using adhesive as the filling material 26 has been described, any material that can fill the gap in the cutting element 24 is acceptable, and for example, foam, resin, metal, or fluid may be used. Preferably, a foam or resin with low thermal conductivity is used to suppress the exchange of heat between the heating element 21, the insulating element 22, and the cooling element 23. Moreover, it is sufficient if the heating element 21, the insulating element 22, and the cooling element 23 are integrated via the connecting member 25, and the configuration may not include the filling material 26.

[0036] The method for separating the joined structure according to Embodiment 2 uses a cutting element 24 in which the heating element 21, the heat insulating element 22, and the cooling element 23 are integrated by a connecting member 25. This ensures that the relative positions of the heating element 21, the heat insulating element 22, and the cooling element 23 are reliably maintained, and prevents the heating element 21, the heat insulating element 22, and the cooling element 23 from shifting when the joined structure 11 is cut.

[0037] Embodiment 3. Figure 5 is a top view showing an example of a method for separating a joined structure according to Embodiment 3. The cutting element 24 used in the method for separating a joined structure according to Embodiment 3 includes a gripping portion 27 for gripping the heating element 21, the insulating element 22, and the cooling element 23. As shown in Figure 5, the gripping portion 27 is located outside the joined structure 11 when cutting, and integrates the heating element 21, the insulating element 22, and the cooling element 23. For example, ceramic can be used as the material for the gripping portion 27. The gripping portion 27 can also be divided into a form that sandwiches the heating element 21, the insulating element 22, and the cooling element 23. During dismantling, a load is applied to the gripping portion 27 to hold down and integrate the heating element 21, the insulating element 22, and the cooling element 23, and the structure is moved while gripping it. The cutting element 24 having a gripping portion 27 allows the relative positional relationship of the heating element 21, the insulating element 22, and the cooling element 23 to be maintained, thereby suppressing the dispersion of the heating element 21, the insulating element 22, and the cooling element 23 when the joint structure 11 is cut. Furthermore, since the heating element 21, the insulating element 22, and the cooling element 23 can be handled as a single unit, work efficiency is improved. In addition, the operator of the joint structure separation method can handle the cutting element 24 without directly contacting the heating element 21, which can become hot, thus offering safety advantages.

[0038] Although the description has described the use of ceramic as the material for the gripping portion 27, any material such as plastic or glass fiber reinforced plastic may be used. Preferably, the material for the gripping portion 27 is an insulating material that does not conduct electric current.

[0039] Furthermore, regarding the structure of the gripping portion 27, although a form in which the object is gripped by sandwiching it between divided members and applying a load has been described, it is sufficient if the heating element 21, the heat insulating element 22, and the cooling element 23 can be integrated into one unit. For example, the gripping portion 27 may be constructed in which the heating element 21, the heat insulating element 22, and the cooling element 23 are integrated using adhesive between the divided members. Moreover, the gripping portion 27 is not limited to a structure having divided surfaces; for example, the heating element 21, the heat insulating element 22, and the cooling element 23 can be integrated by passing them through holes having the same diameter as the heating element 21, the heat insulating element 22, and the cooling element 23 provided in the gripping portion 27 and potting them with resin or the like.

[0040] The method for separating a joined structure according to Embodiment 3 uses a gripping portion 27 that integrates the heating element 21, the insulating element 22, and the cooling element 23 outside the joined structure 11. Therefore, in the method for separating a joined structure according to Embodiment 3, the relative positions of the heating element 21, the insulating element 22, and the cooling element 23 are easily maintained, so that the heating element 21, the insulating element 22, and the cooling element 23 do not become disorganized when the joined structure 11 is cut. In addition, the person performing the method for separating a joined structure according to Embodiment 3 can handle the heating element 21, the insulating element 22, and the cooling element 23 as a single unit, thus improving work efficiency.

[0041] Embodiment 4. Figure 6 is a top view showing an example of a joint structure according to Embodiment 4. Figure 7 is a cross-sectional view of the joint structure according to Embodiment 4. Figure 7 shows a cross-section along the line VII-VII in Figure 6.

[0042] The joint structure 11 according to Embodiment 4 has a configuration in which a cutting element 24, consisting of a heating element 21, an insulating element 22, and a cooling element 23, is embedded inside the joint structure 11, which consists of a first material 1 made of thermoplastic plastic and a second material 2 of any material. The heating element 21 generates heat when exposed to external stimuli. The cutting element 24 is positioned on the joint surface 3 between the first material 1 and the second material 2. The joint structure 11 is used with the cutting element 24 as an integrated unit. When separating and dismantling, the heating element 21 is heated and the cutting element 24 is moved in the direction of travel shown in Figure 6, thereby separating and dismantling the first material 1 and the second material 2.

[0043] FIG. 8 is a top view showing another example of the joined structure according to the fourth embodiment. Further, FIG. 9 is a top view showing still another example of the joined structure according to the fourth embodiment. As the first material 1, for example, nylon 6 resin can be used, and as the second material 2, for example, an aluminum alloy can be used. Joining of the first material 1 and the second material 2 can be achieved, for example, by melting the first material 1 and welding it to the second material 2. By arranging the cutting element 24 on the joining surface 3 of the second material 2 during welding, the first material 1, the second material 2 and the cutting element 24 can be integrated after welding. As shown in FIGS. 8 and 9, by exposing a part of the cutting element 24 to the outside of the joined structure 11, the exposed part of the cutting element 24 can be grasped.

[0044] As for the arrangement of the cutting element 24, for example, as shown in FIG. 6, the cutting element 24 may be arranged linearly inside the joined structure 11, or as shown in FIG. 8, it may be arranged to have a curved portion inside the joined structure 11. Further, as shown in FIG. 9, the cutting element 24 may be arranged so as to have a closed curved surface region. In this case, the cutting element 24 is preferably arranged at a position close to the end of the joining surface 3 of the joined structure 11. Specifically, the cutting element 24 is arranged at a position that passes through 90% or more of the joining surface 3 when moved in the traveling direction as shown in FIGS. 6, 8 and 9. Accordingly, when the cutting element 24 is moved, the cutting element 24 can pass through a wide range of the joining surface 3, so that the first material 1 and the second material 2 can be reliably separated and disassembled.

[0045] As shown in FIG. 8, by matching the direction of the cutting element 24 located outside the joined structure 11 with the traveling direction of the cutting element 24, the first material 1 and the second material 2 can be easily separated and disassembled simply by pulling the cutting element 24 out of the joined structure 11. Further, as shown in FIG. 9, when the cutting elements 24 are arranged to intersect on the joining surface 3, pulling out the cutting elements 24 reduces the closed curved surface region formed by the cutting elements 24 on the joining surface 3, so that the first material 1 and the second material 2 can be easily separated and disassembled.

[0046] In the above description, the case where nylon 6 resin is used as the first material 1 has been described, but any thermoplastic plastic can be used. The thermoplastic plastic may also be used as a base material and contain a reinforcing material. Specific examples of the reinforcing material that can be used include carbon fiber, glass fiber, and inorganic fiber. Furthermore, as the form of fiber reinforcement, short fibers, long fibers, and continuous fibers can be employed.

[0047] In addition, although a configuration in which the cutting element 24 located outside the joined structure 11 is not integrated has been described above, the cutting element 24 may be integrated by a gripping portion 27 or the like.

[0048] Furthermore, although a configuration in which the cutting element 24 is arranged at a position that passes through 90% or more of the joining surface 3 has been described above, the cutting element 24 only needs to be arranged so as to pass through a wide range of the joining surface 3, and may pass through less than 90% thereof. For example, the cutting element 24 may be arranged at a position that passes through 50% or more of the joining surface 3, or may be arranged at a position that passes through 75% or more of the joining surface 3.

[0049] In addition, regarding the method for joining the first material 1 and the second material 2, although a welding configuration has been described above, the first material 1 and the second material 2 may be integrated by another method. Specifically, an adhesive may be disposed between the first material 1 and the second material 2, and the joined structure 11 may be obtained by adhesion. In this case, the cutting element 24 may be positioned between the first material 1 and the adhesive.

[0050] The method for separating a joined structure according to Embodiment 4 uses the joined structure 11 with the cutting element 24 embedded therein. Therefore, the first material 1 and the second material 2 can be separated and disassembled at a required timing without using new parts, devices or the like.

[0051] Embodiment 5. FIG. 10 is a top view showing an example of the joined structure according to Embodiment 5. FIG. 11 is a cross-sectional view of the joined structure according to Embodiment 5. FIG. 11 shows a cross-section taken along line XI-XI in FIG. 10.

[0052] The joint structure 11 according to Embodiment 5 is composed of a first material 1 made of thermoplastic plastic and a second material 2 of any material. Inside the joint structure 11, a cutting element 24 consisting of a heating element 21 that generates heat when exposed to external stimuli, an insulating element 22, and a cooling element 23 is embedded, and in the top view shown in Figure 10, the cutting element 24 is not exposed to the outside of the joint structure 11. The first material 1 does not have to be thermoplastic plastic alone and may contain a reinforcing material. For example, the first material 1 may be a fiber-reinforced plastic with thermoplastic plastic as the base material.

[0053] As shown in Figure 11, the joining structure 11 has a recess 28 on its side so that the end of the cutting element 24 is not exposed. The cutting element 24 is provided with a gripping portion 27, which is not embedded in the joining structure 11 but is located in the recess 28. The end of the cutting element 24 is long enough to protrude from the joining structure 11 when stretched, but it is housed in the recess 28 provided in the joining structure 11 when folded. Furthermore, a cover 29 is provided in the recess 28 to protect the cutting element 24.

[0054] For the first material 1, for example, nylon 6 resin can be used, and for the second material 2, for example, an aluminum alloy can be used. First, a space that will become a recess 28 after joining is formed in the first material 1 and the second material 2 before joining. Next, with the cutting element 24, which is provided with a gripping portion 27, placed on the joining surface 3 of the first material 1 before joining, the second material 2 is placed after being heated to a point above the melting point of the first material 1. At this time, the gripping portion 27 is positioned in the recess 28. As a result, the first material 1 melts and the first material 1 and the second material 2 are joined, and a joined structure 11 with the cutting element 24 and gripping portion 27 is manufactured. Finally, a sheet-like cover 29 is attached so as to cover the recess 28 of the joined structure 11. The material of the cover 29 can be an aluminum alloy, and the attachment method can be, for example, adhesive.

[0055] During dismantling, the cover 29 is removed by cutting or other methods to allow access to the recessed portion 28 from outside the joint structure 11. Next, the gripping portion 27 is removed from the joint structure 11. In this state, a trigger supply source such as a power supply 31 is connected to the heating element 21, and the cutting element 24 is moved while the heating element 21 is heated, thereby separating and dismantling the first material 1 and the second material 2.

[0056] Although a configuration in which the cutting element 24 has a gripping portion 27 has been described, the cutting element 24 does not necessarily have to have a gripping portion 27.

[0057] Furthermore, although a configuration in which the gripping portion 27 is positioned in the recessed portion 28 and not embedded in the joining structure 11 has been described, a part of the gripping portion 27 may be embedded in the joining structure 11.

[0058] Furthermore, although the gripping portion 27 has been described as integrating all of the heating element 21, the insulating element 22, and the cooling element 23, the gripping portion 27 only needs to integrate at least two of the heating element 21, the insulating element 22, and the cooling element 23.

[0059] Furthermore, although a configuration in which the joining structure 11 has a cover 29 has been described, the joining structure 11 does not necessarily have to have a cover 29.

[0060] Furthermore, although the cover 29 is described as being made of an aluminum alloy, any material can be used. For example, the cover 29 can be made of metal, resin, or inorganic materials such as ceramics.

[0061] Furthermore, although the method of attaching the cover 29 has been described as adhesive, any other joining method can be used. For example, the cover 29 may be attached by adhesive, welding, or mechanical joining such as bolting.

[0062] Furthermore, although the cover 29 has been described as having a sheet-like shape, any shape of cover 29 can be used as long as it has a portion that covers the opening of the recessed portion 28.

[0063] The joint structure separation method according to Embodiment 5 uses a joint structure 11 in which a cutting element 24 is arranged in a recessed portion 28, so that the cutting element 24 is not exposed to the outside of the joint structure 11 when the joint structure 11 is in use. For this reason, the joint structure separation method according to Embodiment 5 can protect the cutting element 24 when the joint structure 11 is in use.

[0064] The configurations shown in the above embodiments are merely examples of the content, and can be combined with other known technologies. It is also possible to omit or modify parts of the configuration without departing from the gist of the invention.

[0065] 1. First material, 2. Second material, 3. Joining surface, 11. Joining structure, 21. Heating element, 22. Insulating element, 23. Cooling element, 24. Cutting element, 25. Connecting member, 26. Filling material, 27. Gripping part, 28. Recessed part, 29. Cover, 31. Power supply.

Claims

1. A method for separating a bonded structure having a first material containing a thermoplastic and a second material bonded to the first material, comprising the steps of: bringing a cutting element, which includes a heating element that generates heat upon receiving an external stimulus, a cooling element that moves while maintaining a relative positional relationship with the heating element to cool the first material, and a heat insulating element disposed between the heating element and the cooling element and moving while maintaining a relative positional relationship with each of the heating element and the cooling element, into contact with the bonded surface between the first material and the second material from the heating element side while the external stimulus is supplied to the heating element; and moving the cutting element in a direction of travel with the heating element side facing forward to separate the first material and the second material.

2. The method for separating a joined structure according to claim 1, characterized in that the heating element, the insulating element, and the cooling element are moved in an integrated state by a connecting member.

3. The method for separating a joined structure according to claim 2, characterized in that at least one portion of the heating element and the cooling element is exposed without being covered by the connecting member.

4. The method for separating a jointed structure according to any one of claims 1 to 3, characterized in that a gripping portion is provided on the cutting element for integrating the heating element, the insulating element, and the cooling element in a portion that does not come into contact with the jointed structure during separation of the first material and the second material.

5. The method for separating a junction structure according to any one of claims 1 to 4, characterized in that the external stimulus is an electric current.

6. The method for separating a bonded structure according to claim 5, characterized in that the electrical resistance of the heating element is 0.5 μΩ·m or more and 10 μΩ·m or less.

7. The method for separating a bonded structure according to any one of claims 1 to 6, characterized in that the cooling body cools the first material by the Peltier effect.

8. The method for separating a bonded structure according to claim 7, characterized in that the electrical resistance value of the cooling element is smaller than the electrical resistance value of the heating element.

9. A method for separating a jointed structure according to any one of claims 1 to 8, characterized in that at least one of the heating element, the insulating element, and the cooling element is separated in a linear manner from the first material to the second material.

10. A joining structure comprising: a first material including a thermoplastic; a second material joined to the first material; a cutting element having a heating element that generates heat upon receiving an external stimulus; a cooling element that moves while maintaining its relative positional relationship with the heating element to cool the first material; and a heat insulating element disposed between the heating element and the cooling element, which moves while maintaining its relative positional relationship with each of the heating element and the cooling element, wherein the cutting element is embedded in the joining surface between the first material and the second material, and a portion of each of the heating element, the heat insulating element and the cooling element is exposed to the outside of the first material and the second material.

11. The joining structure according to claim 10, characterized in that the cutting element has a gripping portion that integrates any two or all three of the heating element, the insulating element, and the cooling element on the outside of the first material and the second material.

12. The joint structure according to claim 10 or 11, characterized in that at least one of the first material and the second material is provided with a recess, and the end of the cutting element is housed in the recess.

13. The joint structure according to claim 12, characterized by comprising a cover that covers the recessed portion.

14. The joint structure according to claim 12 or 13, characterized in that the ends of the heating element, the insulating element, and the cooling element are bent and housed in the recessed portion.

15. The joint structure according to any one of claims 10 to 14, characterized in that the first material is a fiber-reinforced plastic with a thermoplastic as the base material.

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