Method for joining members comprising material containing thermoplastic resin

Abstract

Provided is a method for joining, by direct thermal welding, two members that comprise a material containing a thermoplastic resin, wherein deformation of the two members due to flowing of the thermoplastic resin can be reliably prevented.　This method includes, in sequence: a step in which a first member is placed on an upper surface of a first heat source; a step in which a site to be joined of a second member is placed on an upper surface of the first member; a step in which a heat-insulating material is placed on an upper surface of the site to be joined of the second member; a step in which a second heat source is placed on the heat-insulating material and the site to be joined of the second member; a step in which a downward load is imposed on the second heat source and the heat-insulating material; a step in which a resin flow prevention jig is placed on the upper surface of the first member so as to surround the site to be joined of the second member; a step in which a downward load is imposed on the resin flow prevention jig; and a step in which the first heat source is heated to a temperature lower than the weldable temperature of the thermoplastic resin and the second heat source is heated to a temperature higher than the weldable temperature of the thermoplastic resin and lower than the degradation temperature of the thermoplastic resin.

Description

Method for joining components made of a material containing a thermoplastic resin

[0001] FIELD OF THE DISCLOSURE The present disclosure relates to methods for joining components made of thermoplastic-containing materials, such as thermoplastic composite materials.

[0002] As a method for joining members made of a material containing a thermoplastic resin, direct heat welding has been proposed, in which the two members to be joined are heated to melt the thermoplastic resin contained in both members, and the two members are joined via the molten thermoplastic resin.

[0003] Patent Document 1 proposes a method for joining a first member and a second member, both of which are made of a material containing a thermoplastic resin, in which the first member is placed on a first heat source, the second member is placed on the first member, the second heat source is positioned above the second member, and the second heat source is then lowered to press its lower surface against the upper surface of the second member. In this case, the temperature of the first heat source is set to a temperature lower than the melting point of the thermoplastic resin, while the temperature of the second heat source is set to a temperature higher than the melting point and lower than the thermal decomposition temperature of the thermoplastic resin.

[0004] By setting the temperatures of the first heat source and the second heat source as described above, the portions of the members to be joined (the first member and the second member) that reach a temperature equal to or higher than the melting point of the thermoplastic resin are limited to the second member and the vicinity of the joining surfaces of both members. That is, the temperature of the first member, except for the vicinity of the joining surfaces, is kept below the melting point of the thermoplastic resin. Therefore, welding is ensured at the joining surfaces, while the flow of the thermoplastic resin is suppressed in other portions of the first member, preventing deformation of the members to be joined.

[0005] Furthermore, Patent Document 1 also proposes a method for preventing deformation of the members to be joined due to the flow of thermoplastic resin that inevitably occurs near the joining surfaces of the members to be joined.

[0006] The first measure involves providing a recess on the underside of the second heat source that is shaped to accommodate the portion of the second member to be joined (the portion above the joining surface). When the second heat source is lowered and the portion of its underside, excluding the recess, comes into contact with the upper surface of the first member, the portion of the second member to be joined is contained within a space surrounded by the inner surface of the recess and the upper surface of the first member. Therefore, even if a flow of the thermoplastic resin occurs near the joining surface, the flow is limited to this space, preventing deformation of the joined members.

[0007] The second measure involves placing a U-shaped jig on the top surface of the first member so that it surrounds the joint portion of the second member on three sides. When the second heat source is lowered and its bottom surface contacts the top surface of the joint portion of the second member, the joint portion of the second member is surrounded on three sides by the inner surface of the jig on the top surface of the first member. Therefore, even if flow of the thermoplastic resin occurs near the joining surface, the flow is stopped by the inner surface of the jig, preventing deformation of the joint members.

[0008] JP 2023-105471 A

[0009] As described above, Patent Document 1 proposes two measures to prevent deformation of the members to be joined due to the flow of thermoplastic resin that inevitably occurs near the joining surfaces.

[0010] However, the first method does not necessarily effectively prevent deformation of the workpieces when there is a difference in vertical dimension between the recess on the underside of the second heat source and the workpieces of the second member due to manufacturing tolerances or the like. That is, if the vertical dimension of the recess is larger than the vertical dimension of the workpieces, a gap will form between the upper inner surface (ceiling surface) of the recess and the top surface of the workpieces. Conversely, if the vertical dimension of the recess is smaller than the vertical dimension of the workpieces, the recess will not fully accommodate the workpieces, resulting in a gap between the underside of the second heat source and the top surface of the first member. Therefore, in either case, the thermoplastic resin that has become fluid near the joining surfaces will flow into the gap.

[0011] In the second method, the jig is simply placed on the top surface of the first member without moving horizontally, so deformation of the members to be joined cannot be prevented effectively. In other words, if the molten thermoplastic resin in the area of ​​the first member near the joining surface flows onto the top surface of the first member, and the flow pressure exceeds the surface pressure due to the jig's own weight, the jig is lifted, creating a gap between the jig and the top surface of the first member. Therefore, the thermoplastic resin that has become fluid near the joining surface flows out of the area surrounded by the jig through the gap.

[0012] As described above, the method proposed in Patent Document 1 leaves room for further improvement in terms of suppressing the outflow of the thermoplastic resin that has become fluid near the joining surface and preventing deformation of the joined members.

[0013] The present disclosure has been made based on the above considerations, and aims to provide a method for joining two members made of a material containing a thermoplastic resin by direct heat welding, which method can reliably prevent deformation of both members due to flow of the thermoplastic resin.

[0014] In order to solve the above problems, the disclosed method is for joining a first member and a second member, both made of a material containing a thermoplastic resin, and includes the steps of: (a) placing the first member on an upper surface of a first heat source; (b) placing the second member on the upper surface of the first member and bringing the portion of the second member to be joined into contact with the upper surface of the first member; (c) placing a heat insulating material on the upper surface of the portion of the second member to be joined so that its surface is in close contact with the surface of the second member; (d) placing a second heat source having a cutout portion on the upper surfaces of the heat insulating material and the portion of the second member to be joined so that the surface of the heat insulating material is in close contact with the inner surface of the cutout portion; (e) applying a downward load of a desired magnitude to the second heat source and the heat insulating material; (f) placing a first resin flow prevention jig and a second resin flow prevention jig on the upper surface of the first member so that they cooperate to surround the portion to be joined of the second member; (g) applying a downward load of a desired magnitude to the first resin flow prevention jig and the second resin flow prevention jig; (h) heating the first heat source to a predetermined first temperature and the second heat source to a predetermined second temperature, respectively; and (i) cooling the first member and the second member after a predetermined holding time has elapsed since the temperature of the first heat source reached the first temperature and the temperature of the second heat source reached the second temperature, wherein the second temperature is higher than the weldable temperature of the thermoplastic resin and lower than the deterioration temperature of the thermoplastic resin, and the first temperature is lower than the weldable temperature of the thermoplastic resin.

[0015] According to the present disclosure, when two components made of a material containing a thermoplastic resin are joined by direct heat welding, it is possible to obtain the excellent effect of reliably preventing deformation of both components due to the flow of the thermoplastic resin.

[0016] FIG. 1 is a schematic perspective view showing the arrangement of two members made of a material containing a thermoplastic resin and the equipment for joining them when joining is performed by the method of the first embodiment of the present disclosure. FIG. 2 is a schematic cross-sectional view at the center in the width direction (w direction in FIG. 1 ) of the members to be joined, showing a main part of the arrangement of two members made of a material containing a thermoplastic resin and the equipment for joining them when joining is performed by the method of the first embodiment of the present disclosure. FIG. 3 is a schematic perspective view showing a first stage of the procedure for arranging members and equipment for joining them when joining is performed by the method of the first embodiment of the present disclosure. FIG. 4 is a schematic perspective view showing a third stage of the procedure for arranging members and equipment for joining them when joining is performed by the method of the first embodiment of the present disclosure. FIG. 5 is a schematic perspective view showing a fourth stage (final stage) of the procedure for arranging members and equipment for joining them when joining is performed by the method of the second embodiment of the present disclosure. 1 is a schematic cross-sectional view taken at the center in the width direction (w direction in FIG. 4 ) of the members to be joined, showing a main portion of the arrangement of two members made of a material containing a thermoplastic resin and the equipment for joining them when joining them by the method of the second embodiment of the present disclosure; FIG. 2 is a schematic perspective view showing a first stage of the procedure for arranging members and equipment for joining them by the method of the second embodiment of the present disclosure; FIG. 3 is a schematic perspective view showing a third stage of the procedure for arranging members and equipment for joining them by the method of the second embodiment of the present disclosure; FIG. 4 is a schematic perspective view showing a fourth stage of the procedure for arranging members and equipment for joining them by the method of the second embodiment of the present disclosure; FIG. 5 is a schematic perspective view showing a fifth stage (final stage) of the procedure for arranging members and equipment for joining them by the method of the second embodiment of the present disclosure; andFIG. 10 is a schematic cross-sectional view at the center of the width of the members to be joined, showing the main parts of the arrangement of two members made of a material containing a thermoplastic resin and the equipment for joining them when joining using the method of the third embodiment of the present disclosure.

[0017] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings.

[0018] First, a joining method according to a first embodiment of the present disclosure will be described below with reference to FIGS. 1, 2, and 3A to 3D.

[0019] 1 and 2 show the arrangement of two members (members to be joined) made of a material containing a thermoplastic resin and the equipment for joining them when joining is performed by the method of the first embodiment of the present disclosure, with Fig. 1 being a schematic perspective view and Fig. 2 being a schematic cross-sectional view at the center of the members to be joined in the width direction (direction w in Fig. 1). Also, Figs. 3A to 3D are schematic perspective views showing first to fourth steps, respectively, of the arrangement procedure (described below) for the members and equipment shown in Fig. 1, and clearly showing the shapes of these members and equipment and their relative positions.

[0020] These figures show the state when a second member M2 made of a material containing thermoplastic resin is joined to an upper surface M1U of a first member M1 made of a material containing thermoplastic resin.

[0021] The material containing thermoplastic resin may be, for example, carbon fiber reinforced plastic (CFRP) made of a thermoplastic resin (e.g., polyether ether ketone (PEEK)) as a base material and carbon fiber as a reinforcing material, but any material containing thermoplastic resin may be used. However, it is preferable that the thermoplastic resin contained in the first member M1 and the second member M2 is the same.

[0022] The first member M1 and the second member M2 are each pre-formed using a molding die. In the illustrated embodiment, the first member M1 is a relatively large, flat, plate-like member (e.g., 2 to 3 mm thick), and the second member M2 is a relatively small, L-shaped, plate-like member (e.g., 2 to 3 mm thick) (see particularly Figure 3A).

[0023] 2 and 3A, the second member M2 has a to-be-joined portion M2W, which is joined to the upper surface M1U of the first member M1, and is a flat, plate-like portion corresponding to one side (the short side in the illustrated embodiment) of the L-shape. Meanwhile, the upright portion M2V, which corresponds to the other side (the long side in the illustrated embodiment) of the L-shape, is oriented perpendicular to the to-be-joined portion M2W. The to-be-joined portion M2W and the upright portion M2V are connected to each other via a circular-arc-shaped curved portion M2R.

[0024] The direction from the to-be-welded portion M2W through the curved portion M2R to the upright portion M2V (or the opposite direction) will be referred to as the longitudinal direction of the second member M2, and the direction perpendicular to this direction will be referred to as the width direction of the second member M2 (corresponding to the w direction in Figure 1). Also, for materials other than the second member M2, the direction that coincides with the width direction of the second member M2 will be referred to as the width direction, and the dimension in this direction will be referred to as the width.

[0025] As shown in FIGS. 2 and 3A, the first member M1 is placed on the upper surface H1U of the first heat source H1, and the second member M2 is placed on the upper surface M1U of the first member M1.

[0026] The first heat source H1 is a flat panel-like piece of equipment, and its upper surface H1U is formed to have a shape and size that allows the entire lower surface of the first member M1 to come into close contact with it.

[0027] A heater and a temperature sensor (both not shown) are embedded inside the first heat source H1. The temperature sensor is embedded so that its temperature measuring part is located immediately below the upper surface H1U of the second member M2, which is in contact with the lower surface of the joining portion M2W of the second member M2.

[0028] As shown in FIGS. 1 and 2 and FIGS. 3B and 3C, a second heat source H2 and a heat insulating material IS are placed on the upper surface of the joining portion M2W of the second member M2.

[0029] The second heat source H2 is a roughly rectangular parallelepiped component, the width of which is substantially equal to the width of the joining portion M2W of the second member M2, and a notch H2R is provided at its bottom. The notch H2R is a void that is open on the bottom surface, front surface, and both side surfaces in the width direction of the second heat source H2, and its height is equal to the height of the insulating material IS, which will be described later. Here, the front surface of the second heat source H2 is the surface that faces the upright portion M2V of the second member M2. The notch H2R is configured to accommodate a portion of the insulating material IS with the surface of the insulating material IS in close contact with its inner surface.

[0030] A heater and a temperature sensor (both not shown) are embedded inside the second heat source H2. The temperature sensor is embedded so that its temperature measuring part is located immediately above the lower surface of the second heat source H2.

[0031] Although not shown in the figure, the second heat source H2 is subjected to a downward load L when its lower surface is in contact with the upper surface of the joining portion M2W of the second member M2. Ｈ２ A load applying mechanism is attached to apply a downward load L (see the arrow in FIG. 2). Ｈ２ When the load is applied, as described above, the heat insulating material IS accommodated in the notch H2R provided in the lower part of the second heat source H2 is also subjected to a downward load L Ｈ２ will be loaded.

[0032] The insulating material IS is a roughly rectangular prism-shaped piece of equipment made of a material with high insulating properties, and has a width substantially equal to the joining portion M2W of the second member M2, and is configured so that a portion of it (preferably at least half of the vertical projected area) is accommodated in the cutout portion H2R of the second heat source H2.

[0033] 1 and 2 (i.e., the state in which joining is performed), the surfaces (front and bottom) of the insulating material IS opposite the cutout portion H2R of the second heat source H2 are shaped to closely contact the surfaces of the upright portion M2V, the curved portion M2R, and the joining portion M2W of the second member M2. This is to provide an insulating effect and control the conduction of heat applied from the second heat source H2 to the upper surface of the joining portion M2W in the longitudinal direction of the second member M2. Therefore, the height of the insulating material IS is set to a value that suppresses the heat conduction so as not to excessively increase the temperature of the upright portion M2V due to the above-mentioned heat conduction (specifically, to prevent at least the thermoplastic resin from becoming flowable).

[0034] Next, the core feature of the present disclosure for reliably preventing deformation of the members to be joined due to flow of the thermoplastic resin in the vicinity of the joining surface will be described below.

[0035] 1, 2, and 3D, a first resin flow prevention jig J1 and a second resin flow prevention jig J2 are placed on the upper surface M1U of the first member M1. More specifically, with respect to the upright portion M2V of the second member M2 as a reference, the first resin flow prevention jig J1 is placed on the same side as the joining portion M2W, and the second resin flow prevention jig J2 is placed on the opposite side of the joining portion M2W on the upper surface M1U of the first member M1 (see FIG. 2). Note that the first resin flow prevention jig J1 and the second resin flow prevention jig J2 are preferably made of a material with high thermal insulation properties.

[0036] The first resin flow prevention jig J1 is a member formed in a U-shape in a plan view, and is composed of a base portion J1B extending in the width direction and two arms J1A extending from both ends of the base portion J1B in the longitudinal direction of the second member M2. The first resin flow prevention jig J1 is formed to have a thickness greater than that of the joining portion M2W of the second member M2.

[0037] The first resin flow prevention jig J1 defines a space surrounded on three sides by its base J1B and two arms J1A, and the surfaces of the base J1B and the two arms J1A that face the space will be referred to as the respective inner surfaces.

[0038] At this time, the inner surface of the base J1B is formed so as to be in close contact with the longitudinal end face of the joining portion M2W of the second member M2, and so that its width is substantially equal to the width of the joining portion M2W of the second member M2.

[0039] Meanwhile, the inner surfaces of the two arms J1A are in close contact with the widthwise end surfaces of the welded portion M2W of the second member M2, with substantially no gaps present. Each of the two arms J1A extends to the opposite side of the welded portion M2W, relative to the upright portion M2V of the second member M2. Note that the state in which substantially no gaps exist does not exclude the presence of gaps that inevitably occur due to manufacturing tolerances of the second member M2.

[0040] The second resin flow prevention jig J2 is a generally rectangular parallelepiped member whose width is substantially equal to the width of the upright portion M2V of the second member M2. Both end faces of the second resin flow prevention jig J2 in the width direction are formed to closely contact the inner surfaces of the two arms J1A of the first resin flow prevention jig J1, which extend from opposite sides of the upright portion M2V of the second member M2, as described above. Furthermore, the surface of the second resin flow prevention jig J2 facing the second member M2 is shaped so as to closely contact the surfaces of the upright portion M2V and the curved portion M2R of the second member M2 with substantially no gaps in the state shown in FIG. 2 (i.e., the state during joining). Note that the substantially no gaps state does not exclude the presence of gaps that inevitably occur due to manufacturing tolerances of the second member M2.

[0041] The first resin flow prevention jig J1 and the second resin flow prevention jig J2 are configured as described above, and thus cooperate to surround the welded portion M2W of the second member M2 and its vicinity.

[0042] Although not shown in the figure, the first resin flow prevention jig J1 is subjected to a downward load L Ｊ１The second resin flow prevention jig J2 is provided with a load applying mechanism for applying a downward load L (see the arrow in FIG. 2). Ｊ２ The load applying mechanisms are attached to the second heat source H2 to apply a downward load L (see arrows in FIG. 2). Ｈ２ This is provided separately from the above-mentioned load applying mechanism for applying the load.

[0043] The heater lead wires and temperature sensor lead wires embedded inside the first heat source H1 and the second heat source H2, respectively, are connected to a general-purpose temperature controller (not shown), and the temperatures of the first heat source H1 and the second heat source H2 are controlled by the temperature controller as described below during the bonding process.

[0044] Furthermore, the downward loads applied to the second heat source H2, the first resin flow prevention jig J1, and the second resin flow prevention jig J2 by ​​their respective unique load application mechanisms are controlled by a controller (not shown).

[0045] Although not shown, a blower is provided to blow air over the first member M1 and the second member M2 in order to cool them after the joining is completed.

[0046] The first member M1 and the second member M2 are joined using the method of the first embodiment of the present disclosure using the above-mentioned first heat source H1, second heat source H2, first resin flow prevention jig J1, and second resin flow prevention jig J2, and details of this method are described below.

[0047] Here, the first member M1 and the second member M2 are assumed to contain the same thermoplastic resin, and the following two temperatures are focused on as temperatures that characterize the thermal properties of the thermoplastic resin: Deterioration temperature (Th): the temperature at which deterioration of the thermoplastic resin occurs Weldable temperature (Tm): the lowest temperature at which welding becomes possible, such as the melting point or glass transition temperature. Note that the relationship Th>Tm usually holds.

[0048] The joining method according to the embodiment of the present disclosure is intended to cause the temperature of the joining region between the first member M1 and the second member M2, located between the two heat sources, to reach the weldable temperature Tm of the thermoplastic resin by simultaneously setting the temperature (first temperature) T1 of the first heat source H1 lower than the weldable temperature Tm of the thermoplastic resin and setting the temperature (second temperature) T2 of the second heat source H2 higher than the weldable temperature Tm of the thermoplastic resin but lower than the degradation temperature Th of the thermoplastic resin. This allows the two members to be welded in the joining region, i.e., the region between the first joining surface (the portion of the upper surface M1U of the first member M1 facing the lower surface of the to-be-joined portion M2W of the second member M2) and the second joining surface (the lower surface of the to-be-joined portion M2W of the second member M2).

[0049] In the bonding method according to the first embodiment of the present disclosure, the temperatures measured by the temperature sensors embedded in the first heat source H1 and the second heat source H2 are controlled by the temperature controller described above to be the first temperature T1 and the second temperature T2, respectively.

[0050] During the joining process, the downward load L applied to the second heat source H2, the first resin flow prevention jig J1, and the second resin flow prevention jig J2 is Ｈ２ , L Ｊ１ and L Ｊ２ is controlled by the above-mentioned controller to have a desired magnitude.

[0051] The bonding according to the method of the first embodiment of the present disclosure is carried out by carrying out the following steps in this order:(a) a step of placing the first member M1 on the upper surface H1U of the first heat source H1 (first stage of the procedure for arranging members and equipment; see Figure 3A); (b) a step of placing the second member M2 on the upper surface M1U of the first member M1 and bringing its joining portion M2W into contact with the upper surface M1U of the first member M1 (first stage of the procedure for arranging members and equipment; see Figure 3A); (c) a step of placing the insulating material IS on the upper surface of the joining portion M2W of the second member M2 so that the surface of the insulating material IS is in close contact with the surface of the second member M2 (second stage of the procedure for arranging members and equipment; see Figure 3B). (d) placing the second heat source H2 on the upper surfaces of the insulating material IS and the joining portion M2W of the second member M2 so that the surface of the insulating material IS is in close contact with the inner surface of the cutout portion H2R (third stage of the procedure for arranging components and equipment; see Figure 3C); (e) controlling the specific load application mechanism with a controller so that the downward load applied to the second heat source H2 (and the insulating material IS) is of the desired magnitude; (f) placing the first resin flow prevention jig J1 and the second resin flow prevention jig J2 on the upper surface M1U of the first member M1 so that they cooperate to surround the joining portion M2W of the second member M2 (fourth stage (final stage) of the procedure for arranging components and equipment; see Figure 3D). (g) A step of controlling a load application mechanism specific to each jig by a controller so that the downward load applied to each of the first resin flow prevention jig J1 and the second resin flow prevention jig J2 is of a desired magnitude; (h1) A step of heating the first heat source H1 to a first temperature T1 (controlling the on / off of the heater embedded in the first heat source H1 by a temperature controller so that the temperature measured by the temperature sensor embedded in the first heat source H1 becomes the first temperature T1); (h2) A step of heating the second heat source H2 to a second temperature T2 (controlling the on / off of the heater embedded in the second heat source H2 by a temperature controller so that the temperature measured by the temperature sensor embedded in the second heat source H2 becomes the second temperature T2). (i) A step of cooling the first member M1 and the second member M2 (by blowing air onto them using a blower) after a predetermined holding time has elapsed since the temperature measured by the temperature sensor embedded in the first heat source H1 reaches the first temperature T1 and the temperature measured by the temperature sensor embedded in the second heat source H2 reaches the second temperature T2.

[0052] In the joining method described above, the to-be-joined portion M2W of the second member M2 and its vicinity are completely surrounded by the first resin flow prevention jig J1 and the second resin flow prevention jig J2. Furthermore, the first resin flow prevention jig J1 and the second resin flow prevention jig J2 are pressed against the upper surface M1U of the first member M1 by a downward load applied by the load application mechanism. Therefore, even if the thermoplastic resin becomes fluid near the lower surface of the to-be-joined portion M2W of the second member M2 and near the upper surface of the first member M1 facing this, the thermoplastic resin is prevented from flowing out to the surroundings, thereby preventing deformation of the to-be-joined members.

[0053] Furthermore, since a load applying mechanism that applies a downward load to each of the first resin flow prevention jig J1 and the second resin flow prevention jig J2 is provided separately from the load applying mechanism that applies a downward load to the second heat source H2, even if there is variation in the thickness (vertical dimension) of the joining portion M2W of the second member M2 due to manufacturing tolerances, the first resin flow prevention jig J1 and the second resin flow prevention jig J2 can be reliably pressed against the upper surface M1U of the first member M1. This more reliably prevents the thermoplastic resin, which has become fluid, from leaking out to the surrounding area.

[0054] Next, a joining method according to a second embodiment of the present disclosure will be described below with reference to FIGS. 4, 5, 6A to 6E, and 7. FIG.

[0055] 4 and 5 show the arrangement of two members (joined members) made of a material containing a thermoplastic resin and the equipment used to join them when joining them using the method of the second embodiment of the present disclosure. Fig. 4 is a schematic perspective view, and Fig. 5 is a schematic cross-sectional view of the center of the members in the width direction (direction w in Fig. 4). Also, Figs. 6A to 6E are schematic perspective views showing steps 1 to 5, respectively, of the arrangement procedure (described below) for the members and equipment shown in Fig. 4, and are intended to clearly show the shapes and relative positions of these members and equipment. Furthermore, Fig. 7 is a schematic perspective view showing the shapes and fastening mode of two clamping jigs used in joining using the method of the second embodiment of the present disclosure.

[0056] The joining method of the second embodiment of the present disclosure is a modification of the joining method of the first embodiment, which is modified to more reliably prevent deformation of the joined members due to the flow of thermoplastic resin near the joining surfaces.

[0057] The joining method of the second embodiment of the present disclosure differs from the joining method of the first embodiment in that a tightening jig is added to tightly attach each of the two resin flow prevention jigs to the second member M2. Therefore, the following are the same as those in the joining method of the first embodiment: The shapes and joining manner of the first member M1 and the second member M2 (joined members); The shapes, functions, and arrangement of the first heat source H1 and the second heat source H2 relative to the joined members; and The shapes and arrangement of the insulating material IS, the first resin flow prevention jig J1, and the second resin flow prevention jig J2 relative to the joined members. Therefore, redundant explanations of these will be omitted.

[0058] As shown in FIG. 4, in the joining method according to the second embodiment of the present disclosure, a first clamping jig CJ1 and a second clamping jig CJ2 are additionally provided.

[0059] As shown in Figure 5, the first clamping jig CJ1 is a member placed on the upper surface J1U of the first resin flow prevention jig J1 on the same side as the joining portion M2W with respect to the upright portion M2V of the second member M2 (see also Figures 6C and 6D).

[0060] As shown in Figures 4 and particularly 7, the first tightening jig CJ1 is a member formed in a U-shape when viewed in a plane, and consists of a base CJ1B extending in the width direction and two arms CJ1A each extending in the longitudinal direction of the second member M2 from both ends of the base CJ1B as a starting point.

[0061] The first tightening jig CJ1 defines a space surrounded on three sides by its base CJ1B and two arms CJ1A, and the surfaces of the base CJ1B and the two arms CJ1A that face the space will be referred to as their respective inner surfaces.

[0062] In this case, the inner surface of the base CJ1B is positioned outward from the inner surface of the base J1B of the first resin flow prevention jig J1, and the inner surfaces of the two arms CJ1A are positioned outward from the inner surfaces of the two arms J1A of the first resin flow prevention jig J1. Here, "outward" refers to the side away from the surface of the second heat source H2. This positions the inner surfaces of the base CJ1B and the two arms CJ1A apart from the outer surface of the second heat source H2, preventing the first clamping jig CJ1 from being excessively heated by heat conduction from the second heat source H2. Furthermore, as shown in FIG. 5 in particular, when the first clamping jig CJ1 is placed on the upper surface J1U of the first resin flow prevention jig J1, its lower surface is positioned away from the upper surface M1U of the first member M1.

[0063] A notch CJ1R is formed in the lower portion of the first clamping jig CJ1. The notch CJ1R is shaped so that its inner surface is in close contact with at least the upper surface J1U and the outer surface J1E (the longitudinal end surface of the second member M2) opposite the inner surface of the base J1B of the first resin flow prevention jig J1 (see FIG. 5). This allows a load to be applied to the first resin flow prevention jig J1 via the inner surface of the notch CJ1R of the first clamping jig CJ1, as described below.

[0064] As shown in Figure 5, the second clamping jig CJ2 is a member placed on the upper surface J2U of the second resin flow prevention jig J2 on the opposite side of the joining portion M2W with respect to the upright portion M2V of the second member M2 as a reference (see also Figures 6D and 6E).

[0065] 4 and 5, and particularly Fig. 7, the second clamping jig CJ2 is an L-shaped member when viewed from the side in the width direction, and has a notch CJ2R formed in its lower part. Note that, as can be seen particularly in Fig. 5, when the second clamping jig CJ2 is placed on the upper surface J2U of the second resin flow prevention jig J2, its lower surface is separated from the upper surface M1U of the first member M1, and the surface facing the upright portion M2V of the second member M2 is separated from the upright portion M2V of the second member M2.

[0066] The cutout portion CJ2R is formed in the widthwise center of the second clamping jig CJ2 so that its inner surface is in close contact with at least the upper surface J2U and the longitudinal end surface J2E of the second member M2 (see FIG. 5). This allows a load, as described below, to be applied to the second resin flow prevention jig J2 via the inner surface of the cutout portion CJ2R of the second clamping jig CJ2.

[0067] 6E and 7, the cutout portions CJ2R are formed at both widthwise ends of the second tightening jig CJ2 in a shape that accommodates downwardly each of the two arms CJ1A of the first tightening jig CJ1. Through holes CJ2H are formed in the second tightening jig CJ2 in these portions (see FIG. 7). Meanwhile, screw holes CJ1H are formed in the longitudinal end faces of each of the two arms CJ1A of the first tightening jig CJ1 that are accommodated in the cutout portions of the second tightening jig CJ2 in these portions (see FIG. 7).

[0068] 4, 6E, and 7, with the longitudinal end faces of the two arms CJ1A of the first tightening jig CJ1 in contact with the inner surfaces of the opposing notches CJ2R of the second tightening jig CJ2, two bolts B are inserted into the through holes CJ2H of the second tightening jig CJ2 and screwed into the screw holes CJ1H of the first tightening jig CJ1. As a result, the first tightening jig CJ1 and the second tightening jig CJ2 are brought into close contact with each other in the longitudinal direction of the second member M2. At this time, the first resin flow prevention jig J1 is pushed toward the second resin flow prevention jig J2 by ​​the first tightening jig CJ1 via its surface J1E, and the second resin flow prevention jig J2 is pushed toward the first resin flow prevention jig J1 by the second tightening jig CJ2 via its surface J2E. As a result, the inner surface of the base J1B of the first resin flow prevention jig J1 comes into close contact with the longitudinal end surface of the joining portion M2W of the second member M2, and the surface of the second resin flow prevention jig J2 facing the second member M2 comes into close contact with the surfaces of the upright portion M2V and the curved portion M2R of the second member M2, respectively, in the longitudinal direction of the second member M2. This makes it possible to more reliably prevent the thermoplastic resin from flowing out to the surrounding area than in the method of the first embodiment, even if the thermoplastic resin becomes flowable near the bottom surface of the joining portion M2W of the second member M2 and near the opposing top surface of the first member M1.

[0069] In the method of the first embodiment, a downward load is applied to each of the first resin flow prevention jig J1 and the second resin flow prevention jig J2 by ​​a load application mechanism independent of the load application mechanism for applying a downward load to the second heat source H2. However, in the method of the second embodiment, a downward load L is applied to each of the first clamping jig CJ1 and the second clamping jig CJ2 by ​​the load application mechanism. ＣＪ１ , L ＣＪ２ (See the arrow in FIG. 5) is applied to the second heat source H2. As in the case of the method of the first embodiment, a downward load L Ｈ２ (See the arrow in FIG. 5) is loaded.

[0070] The joining by the method of the second embodiment of the present disclosure is performed by carrying out the following steps in this order: (a) placing the first member M1 on the upper surface H1U of the first heat source H1 (first stage of the procedure for arranging members and equipment; see FIG. 6A ); (b) placing the second member M2 on the upper surface M1U of the first member M1 and bringing the joining portion M2W of the second member M2 into contact with the upper surface M1U of the first member M1 (first stage of the procedure for arranging members and equipment; see FIG. 6A ); and (c) placing the insulating material IS on the upper surface of the joining portion M2W of the second member M2 so that the surface of the insulating material IS is in close contact with the surface of the second member M2 (second stage of the procedure for arranging members and equipment; see FIG. 6B ). (d) a step of placing a second heat source H2 on the upper surfaces of the insulating material IS and the joining portion M2W of the second member M2 so that the surface of the insulating material IS is in close contact with the inner surface of the cutout portion H2R (second step in the procedure for arranging members and equipment; see Figure 6B); (e) a step of controlling the specific load application mechanism by a controller so that the downward load applied to the second heat source H2 (and the insulating material IS) is of the desired magnitude; (f) a step of placing a first resin flow prevention jig J1 and a second resin flow prevention jig J2 on the upper surface M1U of the first member M1 (third step in the procedure for arranging members and equipment; see Figure 6C); (F1) a step of placing a first tightening jig CJ1 on the upper surface J1U of the first resin flow prevention jig J1 (fourth step in the procedure for arranging members and equipment; see Figure 6D). (F2) A step of placing the second clamping jig CJ2 on the upper surface J2U of the second resin flow prevention jig J2 (the fifth step in the arrangement procedure of components and equipment;(See FIG. 6E) (F3) Step of bringing the first tightening jig CJ1 and the second tightening jig CJ2 into close contact with each other in the longitudinal direction of the second member M2 using bolts B; (g) Step of controlling the load application mechanism specific to each jig by a controller so that the downward load applied to each of the first tightening jig CJ1 and the second tightening jig CJ2 is of a desired magnitude; (h1) Step of heating the first heat source H1 to a first temperature T1 (controlling the on / off of the heater embedded in the first heat source H1 by a temperature controller so that the temperature measured by the temperature sensor embedded in the first heat source H1 becomes the first temperature T1); (h2) Step of heating the second heat source H2 to a second temperature T2 (controlling the on / off of the heater embedded in the second heat source H2 by a temperature controller so that the temperature measured by the temperature sensor embedded in the second heat source H2 becomes the second temperature T2). (i) cooling the first member M1 and the second member M2 (by blowing air onto them using a blower) after a predetermined holding time has elapsed since the temperature measured by the temperature sensor embedded in the first heat source H1 reaches a first temperature T1 and the temperature measured by the temperature sensor embedded in the second heat source H2 reaches a second temperature T2;

[0071] In the joining method described above, the first and second clamping jigs CJ1 and CJ2, which surround the to-be-joined portion M2W of the second member M2 and its vicinity, are brought into close contact with the second member M2 by the first clamping jig CJ1 and the second clamping jig CJ2, respectively, and are further pressed against the upper surface M1U of the first member M1 by a downward load applied by the load application mechanism. Therefore, even if the thermoplastic resin becomes fluid near the lower surface of the to-be-joined portion M2W of the second member M2 and near the upper surface of the first member M1 facing this, it is possible to reliably prevent the thermoplastic resin from flowing out to the surrounding area and, ultimately, to prevent deformation of the to-be-joined members.

[0072] Next, a joining method according to a third embodiment of the present disclosure will be described below with reference to FIG.

[0073] FIG. 8 is a schematic cross-sectional view at the center in the width direction of the members to be joined, showing the main parts of the arrangement of two members made of a material containing a thermoplastic resin and the equipment for joining them when joining them using the method of the third embodiment of the present disclosure.

[0074] The joining method of the third embodiment of the present disclosure is a modification of the joining method of the first embodiment so that it can be applied even when the portion of the second member to be joined is very thick.

[0075] In the joining method of the first embodiment, if the thickness of the second member to be joined exceeds a certain limit, the temperature of the joining region between the first and second members may not reach the temperature at which the thermoplastic resin can be welded unless the heat output of the second heat source is sufficient. Even if the second heat source has sufficient heat output, the temperature of at least a portion of the joining region (near the second heat source) may exceed the temperature at which the thermoplastic resin can be decomposed due to a temperature gradient that occurs in the joining region. One factor that causes this situation is that, in the joining method of the first embodiment, the temperature of the first heat source is set lower than the temperature at which the thermoplastic resin can be welded.

[0076] Therefore, in the joining method of the third embodiment, the configuration of the first heat source is modified compared to the joining method of the first embodiment so that the temperature of the joining area of ​​the first member and the second member can reach the temperature at which the thermoplastic resin can be welded.

[0077] 8, the first heat source H1m is configured to include a plurality of sections separated from each other by thermal insulation. More specifically, the first heat source H1m includes a high-temperature section H1mH located directly below the to-be-joined portion M2mW of the second member M2m in a state in which joining is being performed, an insulating section H1mIS arranged to surround the high-temperature section H1mH, and a low-temperature section H1mL arranged to surround the insulating section H1mIS.

[0078] The high-temperature section H1mH is a rectangular parallelepiped section, and has a heater and a temperature sensor (both not shown) embedded therein, similar to the first heat source H1 in the bonding method of the first embodiment.

[0079] In a plan view (not shown), the area occupied by the high-temperature section H1mH does not extend outside the area occupied by the welded portion M2mW of the second member M2m. In one embodiment, the area occupied by the high-temperature section H1mH is the same as the area occupied by the welded portion M2mW of the second member M2m. Preferably, the area occupied by the high-temperature section H1mH is smaller than the area occupied by the welded portion M2mW of the second member M2m. In this case, the former area is inside the latter area, and the outer edges of the former area and the latter area are separated from each other in all directions. By configuring the high-temperature section H1mH in this compact manner, as will be described later, the area of ​​the welded members exposed to temperatures higher than the weldable temperature of the thermoplastic resin can be reduced, thereby suppressing the flow of the thermoplastic resin.

[0080] The heat insulating section H1mIS is a hollow rectangular prism-shaped section having inner surfaces in close contact with each of the four sides of the rectangular parallelepiped high temperature section H1mH, and is made of a material with high heat insulating properties.

[0081] The low-temperature section H1mL is a section having an inner surface that is in close contact with each of the outer surfaces of the insulating section H1mIS, and similar to the first heat source H1 in the joining method of the first embodiment, a heater and a temperature sensor (both not shown) are embedded inside.

[0082] As described above, the to-be-joined portion M2mW of the second member M2m is significantly thicker than the to-be-joined portion M2W of the second member M2 in the joining method of the first embodiment, and to accommodate this difference in thickness, minor changes have been made to the shapes of the insulating material ISm and the second heat source H2m. That is, the height of the insulating material ISm is lower than that of the insulating material IS in the joining method of the first embodiment, and the height of the cutout portion of the second heat source H2m is also lower than that of the cutout portion of the second heat source H2 in the joining method of the first embodiment.

[0083] In the joining method of the third embodiment, not only the second heat source H2m but also the high-temperature section H1mH of the first heat source H1m is heated to a temperature (third temperature T3) that is higher than the weldable temperature of the thermoplastic resin but lower than the deterioration temperature. This ensures that even if the welded portion M2mW of the second member M2m is thick, the joining area between the first member M1 and the second member M2m located between the two heat sources is sufficiently heated to reach the weldable temperature of the thermoplastic resin. The third temperature T3 may be equal to or different from the second temperature T2.

[0084] On the other hand, the low-temperature section H1mL of the first heat source H1m is set to a temperature lower than the welding temperature of the thermoplastic resin, thereby preventing the thermoplastic resin from becoming flowable in areas of the first member M1 other than the joining area.

[0085] That is, bonding by the method of the third embodiment of the present disclosure is performed by performing steps (a) to (i) of the method of the first embodiment described above in this order, but step (h1) is modified as follows: (h1) a step of heating the high-temperature section H1mH of the first heat source H1m to a third temperature T3 (controlling the on / off of the heater embedded in the high-temperature section H1mH by a temperature controller so that the temperature measured by the temperature sensor embedded in the high-temperature section H1mH becomes the third temperature T3), and heating the low-temperature section H1mL of the first heat source H1m to the first temperature T1 (controlling the on / off of the heater embedded in the low-temperature section H1mL by a temperature controller so that the temperature measured by the temperature sensor embedded in the low-temperature section H1mL becomes the first temperature T1).

[0086] (Aspects of the Present Disclosure) A method of a first aspect of the present disclosure is for joining a first member and a second member, both of which are made of a material containing a thermoplastic resin, and includes the steps of: (a) placing the first member on an upper surface of a first heat source; (b) placing the second member on the upper surface of the first member and bringing a portion of the second member to be joined into contact with the upper surface of the first member; (c) placing a heat insulating material on the upper surface of the portion of the second member to be joined such that its surface is in close contact with the surface of the second member; (d) placing a second heat source having a cutout portion on the upper surfaces of the heat insulating material and the portion of the second member to be joined such that the surface of the heat insulating material is in close contact with the inner surface of the cutout portion; (e) applying a downward load of a desired magnitude to the second heat source and the heat insulating material; (f) placing a first resin flow prevention jig and a second resin flow prevention jig on the upper surface of the first member so that they cooperate to surround the portion to be joined of the second member; (g) applying a downward load of a desired magnitude to the first resin flow prevention jig and the second resin flow prevention jig; (h) heating the first heat source to a predetermined first temperature and the second heat source to a predetermined second temperature, respectively; and (i) cooling the first member and the second member after a predetermined holding time has elapsed since the temperature of the first heat source reached the first temperature and the temperature of the second heat source reached the second temperature, wherein the second temperature is higher than the weldable temperature of the thermoplastic resin and lower than the deterioration temperature of the thermoplastic resin, and the first temperature is lower than the weldable temperature of the thermoplastic resin.

[0087] In the method of the second aspect of the present disclosure, immediately after step (f), the method includes the step of: (F) placing a first clamping jig and a second clamping jig on the upper surface of the first member so as to cover the first resin flow prevention jig and the second resin flow prevention jig from above, respectively, and bringing the first clamping jig and the second clamping jig into close contact with each other using bolts; and the downward load applied to the first resin flow prevention jig and the second resin flow prevention jig in step (g) is carried out via the first clamping jig and the second clamping jig.

[0088] In the method of the third aspect of the present disclosure, the first heat source comprises a high-temperature section located directly below the portion to be joined of the second member, an insulating section arranged to surround the high-temperature section, and a low-temperature section arranged to surround the insulating section, and in step (h), the high-temperature section is heated to a temperature higher than the weldable temperature of the thermoplastic resin and lower than the transformation temperature of the thermoplastic resin, while the low-temperature section is heated to a temperature lower than the weldable temperature of the thermoplastic resin.

[0089] B Bolt CJ1 First tightening jig CJ2 Second tightening jig H1, H1m First heat source H1U, H1mU Top surface of first heat source H2 Second heat source H2R Notch of second heat source IS Heat insulating material L Ｈ２ , L Ｊ１ , L Ｊ２ , L ＣＪ１ , L ＣＪ２Load J1 First jig for preventing resin flow J2 Second jig for preventing resin flow M1 First member M1U Top surface of first member M2 Second member M2W Joined portion of second member T1 First temperature T2 Second temperature Th Temperature at which thermoplastic resin changes in quality Tm Temperature at which thermoplastic resin can be welded t Holding time

Claims

1. A method for joining a first member and a second member, both of which are made of a material containing a thermoplastic resin, comprising: (a) placing the first member on an upper surface of a first heat source; (b) placing the second member on the upper surface of the first member and bringing the portion of the second member to be joined into contact with the upper surface of the first member; (c) placing a heat insulating material on the upper surface of the portion of the second member to be joined so that its surface is in close contact with the surface of the second member; (d) placing a second heat source having a cutout on the heat insulating material and the upper surfaces of the portion of the second member to be joined so that the surface of the heat insulating material is in close contact with the inner surface of the cutout; (e) applying a downward load of a desired magnitude to the second heat source and the heat insulating material; (f) placing a first jig for preventing resin flow and a second jig for preventing resin flow on the upper surface of the first member so that they cooperate to surround the portion of the second member to be joined; (g) applying a downward load of a desired magnitude to the first resin flow prevention jig and the second resin flow prevention jig; (h) heating the first heat source to a predetermined first temperature and the second heat source to a predetermined second temperature, respectively; and (i) cooling the first member and the second member after a predetermined holding time has elapsed since the temperature of the first heat source reached the first temperature and the temperature of the second heat source reached the second temperature, wherein the second temperature is higher than the weldable temperature of the thermoplastic resin and lower than the deterioration temperature of the thermoplastic resin, and the first temperature is lower than the weldable temperature of the thermoplastic resin.

2. The method according to claim 1, comprising the step (F) immediately after step (f): (F) placing a first clamping jig and a second clamping jig on the upper surface of the first member so as to cover the first resin flow prevention jig and the second resin flow prevention jig from above, respectively, and bringing the first clamping jig and the second clamping jig into close contact with each other using bolts; and wherein the downward load is applied to the first resin flow prevention jig and the second resin flow prevention jig, respectively, in step (g) via the first clamping jig and the second clamping jig.

3. The method according to claim 1, wherein the first heat source comprises: a high-temperature section located directly below the portion of the second member to be joined; an insulating section arranged to surround the high-temperature section; and a low-temperature section arranged to surround the insulating section; and wherein in step (h), the high-temperature section is heated to a temperature higher than the weldable temperature of the thermoplastic resin and lower than the transformation temperature of the thermoplastic resin, while the low-temperature section is heated to a temperature lower than the weldable temperature of the thermoplastic resin.

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