JP2016068471A - Method for bonding metallic member and resin member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for bonding a metallic member and a resin member, which can achieve bonding between the resin member and the metallic member with sufficient strength.SOLUTION: Provided is a method for bonding a metallic member 11 and a resin member 12 by a hot pressing bonding method, comprising: overlapping a metallic member 11 and a resin member 12 containing reinforcing fibers; providing the members with heat and pressure locally by pressing by a pressing member 16 from the metallic member side to soften and melt the resin member 12; and thereafter solidifying the resin member. The method for bonding a metallic member 11 and a resin member 12 includes a solidification step for performing the solidification by continuing pressing by the pressing member 16 even after a heat supply from the pressing member 16 is terminated.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for joining a metal member and a resin member.

  Conventionally, weight reduction is required in the fields of automobiles, railway vehicles, airplanes, and the like. For example, in the field of automobiles, the use of high-tensile materials has made it possible to make steel sheets thinner, aluminum alloy materials have been used as substitutes for steel materials, and resin materials have also been increasingly used. In these fields, development of joining technology for metal members and resin members is important not only for reducing the weight of the car body, but also for increasing the strength and rigidity of the joining members and improving productivity. is there. So far, a so-called friction stir welding (FSW) method has been proposed as a method for joining a metal member and a resin member. As shown in FIG. 7, the friction stir welding method is a method in which a metal member 211 and a resin member 212 are overlapped, and the rotary tool 216 is rotated and pressed against the metal member 211 to generate frictional heat. In this method, the resin member 212 is melted and then solidified to join the metal member 211 and the resin member 212 together.

  In such a friction stir welding method, for example, a technique (Patent Document 1) is disclosed in which the shape and push-in amount of the rotary tool are set within a specific range from the viewpoint of joining strength and simple joining. Further, in the conventional friction stir welding method, at the end of the joining operation, it is general that the vicinity of the joint is released from the restrained state at the same time as the rotary tool is rotated and separated from the metal member.

  On the other hand, a technique for improving the strength of a resin member by adding a reinforcing fiber to the resin member is known. For example, in the field of compression molding methods, it is a fiber reinforced thermoplastic resin composite material composed of reinforced fibers and a thermoplastic resin from the viewpoint of preventing resin deterioration, improving productivity, and increasing strength and elastic modulus. A compression molding material in which reinforcing fibers having a specific fiber length are contained in a specific volume content and the same fiber axis direction is disclosed (Patent Document 2).

JP 2010-158885 A JP 2004-142165 A

  However, in the conventional friction stir welding method, when a conventional fiber reinforced resin member is used, the bonding strength may be reduced.

  The inventors of the present invention have intensively studied the phenomenon of such a decrease in bonding strength, and as a result, have found that the phenomenon is caused by springback of reinforcing fibers contained in the resin member. Specifically, as shown in FIG. 8A, the pressing member 216 is pressed into the metal member 211, and the region 221 directly below the pressing member of the resin member 212 and its outer peripheral region are melted by frictional heat, and then solidified. As a result, springback occurred in the melted and solidified region of the resin member 212. The spring back is a phenomenon in which the curved reinforcing fiber is released from the restraining force when the resin member 212 is melted and deforms so as to return straight. When such a springback occurs, as shown in FIG. 8B, bubbles are mixed in the melt-solidified region of the resin member 212 to form a bubble layer 222 that appears to be foamed. It is considered that the bond strength is lowered by the occurrence of the intralayer breakage in the low envelope layer 222.

  An object of this invention is to provide the joining method of the metal member and resin member which can achieve joining with sufficient intensity | strength of a resin member and a metal member.

The present invention
Thermo-pressure bonding in which a metal member and a resin member containing reinforcing fibers are superposed, heat and pressure are locally applied by pressing from the metal member side by the pressing member, and the resin member is softened and melted and then solidified A method of joining a metal member and a resin member by a method,
The present invention relates to a method for joining a metal member and a resin member, characterized by including a solidification step in which the solidification is performed by continuing the pressing by the pressing member even after the application of heat by the pressing member is stopped.

The present invention also provides
A first step of superposing the metal member and the resin member; and while rotating the rotary tool, the metal member is pressed against the metal member to generate frictional heat. The resin member is softened and melted by the frictional heat and then solidified. A method of joining a metal member and a resin member by a friction stir welding method including a second step of joining the metal member and the resin member,
The second step relates to a method for joining a metal member and a resin member, characterized in that the second step includes a solidification step of continuing the pressing by the rotary tool even after the rotation of the rotary tool is stopped and performing the solidification.

  According to the joining method of the present invention, even when the reinforcing fiber is contained in the resin member, the joining of the resin member and the metal member can be achieved with sufficient strength.

It is a schematic diagram which shows an example of a part of friction stir welding apparatus suitable for the joining method of the metal member and resin member concerning this invention. It is an enlarged view of the front-end | tip part of an example of the rotation tool as a press member used for the joining method of this invention. It is a schematic sectional drawing for demonstrating an example of the preheating process of this invention. It is a schematic sectional drawing for demonstrating an example of the indentation stirring process of this invention, a stirring maintenance process, and a solidification process. It is a schematic sectional drawing of an example of the joined body of the metal member and resin member which were joined by the method of the present invention. It is the schematic for demonstrating the measuring method of the joint strength in an Example. It is this schematic sketch for demonstrating the joining method of the metal member and resin member in a prior art. (A) is a schematic sectional drawing for demonstrating the joining method of the metal member and resin member in a prior art, (B) is the metal member and resin member in the joined_body | zygote obtained by the method of (A). It is an enlarged view of the joining boundary surface.

  In the joining method of the present invention, the metal member and the resin member are overlapped, and heat and pressure are locally applied by pressing from the metal member side or the resin member side by the pressing member, and the resin member is softened and melted. This is a hot-pressure joining method in which a metal member and a resin member are joined by solidification. The joining method employed in the joining method of the present invention is not particularly limited as long as it is a method of locally applying heat and pressure by a pressing member. For example, a friction stir welding method, an ultrasonic heating joining method, etc. It may be. Preferably, it is a method in which heat and pressure are locally applied from the metal member side by a pressing member, and a friction stir welding method is more preferably employed.

  As will be described in detail later, the friction stir welding method is a method in which a metal member and a resin member are overlapped and a rotating tool as a pressing member is rotated to press the metal member to generate frictional heat. In this method, the resin member is softened and melted by heat and then solidified to join the metal member and the resin member.

  The ultrasonic heating bonding method is a resin member / metal member produced by superposing a metal member and a resin member and causing the pressing member and the resin member to ultrasonically vibrate while pressing the resin member with the pressing member. In this method, the resin member is softened and melted by the frictional heat, and then solidified to join the metal member and the resin member.

  Hereinafter, although the joining method of the present invention employing the friction stir welding method will be described in detail with reference to the drawings, it is apparent that the effects of the present invention can be obtained by other methods as well. In the following description, the stop of rotation of the rotary tool means stop of application of heat by the pressing member in the ultrasonic heating joining method.

[Method of joining metal member and resin member by friction stir welding method]
The joining method (friction stir welding method) of the present invention will be specifically described with reference to FIGS. FIG. 1 is a schematic view showing an example of a part of a friction stir welding apparatus suitable for a method for joining a metal member and a resin member according to the present invention. FIG. 2 is an enlarged view of the tip of an example of a rotary tool used in the joining method of the present invention. FIG. 3 is a schematic sectional view for explaining an example of the preheating step of the present invention. FIG. 4 is a schematic cross-sectional view for explaining an example of the indentation stirring process, stirring maintaining process and solidification process of the present invention. FIG. 5 is a schematic cross-sectional view of an example of a joined body of a metal member and a resin member joined by the method of the present invention. In these drawings, common reference numerals indicate the same members.

(1) Joining Device First, FIG. 1 is a diagram schematically showing an example of a part of a friction stir welding device suitable for carrying out the joining method of the present invention. A friction stir welding apparatus 1 shown in FIG. 1 is configured as a device for friction stir welding a metal member 11 and a resin member 12, and includes a columnar rotary tool 16 as a pressing member.

  As shown in the figure, the rotary tool 16 is applied to the workpiece 10 with the metal member 11 on the top and the resin member 12 on the bottom, by a drive source (not shown) as indicated by an arrow A1. While rotating around the central axis X (see FIG. 2), it moves downward as indicated by an arrow A2. At this time, the rotary tool 16 applies pressure in the pressing region P (scheduled pressing region) on the surface of the metal member 11. Friction heat is generated by the pressing of the rotary tool 16, and the friction heat is conducted to the resin member 12 to soften and melt the resin member 12, and then the molten resin is solidified. As a result, the metal member 11 and the resin member 12 are joined.

  FIG. 2 is an enlarged view of the distal end portion of the rotary tool 16. In FIG. 2, the right half shows the appearance of the rotary tool 16, and the left half shows a cross section. As shown in FIG. 2, the columnar rotary tool 16 has a pin portion 16 a and a shoulder portion 16 b at the distal end portion (lower end portion in FIG. 2). The shoulder portion 16 b is a portion at the tip of the rotary tool 16 including the circular tip surface of the rotary tool 16. The pin portion 16a is a cylindrical portion having a smaller diameter than the shoulder portion 16b, which protrudes outwardly (downward in FIG. 2) from the circular tip surface of the rotary tool 16 on the central axis X of the rotary tool 16. is there. The pin portion 16a is for positioning the rotating tool 16 when the rotating tool 16 that is rotating is first brought into contact with the workpiece 10 and pressed.

  The material of the rotary tool 16 and the dimensions of each part are mainly set according to the metal type of the metal member 11 pressed by the rotary tool 16. For example, when the metal member 11 is made of an aluminum alloy, the rotary tool 16 is made of tool steel (for example, SKD61), the diameter D1 of the shoulder portion 16b is 10 mm, the diameter D2 of the pin portion 16a is 2 mm, and the pin portion 16a protrudes. The length h is set to 0.5 mm. For example, when the metal member 11 is made of steel, the rotary tool 16 is made of silicon nitride, PCBN (cubic boron nitride sintered body), etc., the diameter D1 of the shoulder portion 16b is 10 mm, and the diameter D2 of the pin portion 16a. Is set to 3 mm, and the protruding length h of the pin portion 16a is set to 0.5 mm. Needless to say, these are merely examples, and the present invention is not limited thereto. For example, the diameter D1 of the shoulder portion 16b is usually 5 to 30 mm, preferably 5 to 15 mm, but is not limited thereto.

  Below the rotary tool 16, a cylindrical receiving member 17 having the same diameter as the rotary tool 16 or a larger diameter than the rotary tool 16 is arranged coaxially with the rotary tool 16. The receiving member 17 is moved upward with respect to the work 10 as shown by an arrow A3 by a driving source (not shown). The upper end surface of the receiving member 17 abuts on the lower surface of the workpiece 10 (more specifically, the lower surface of the resin member 12) by the time the rotating tool 16 starts pressing the workpiece 10 at the latest. The support 17 sandwiches the workpiece 10 between the rotary tool 16 and supports the workpiece 10 from below against the pressing force during a pressing period by the rotary tool 16, that is, during friction stir welding. Note that the receiving tool 17 does not necessarily have to be moved in the direction of the arrow A3, and a method of moving the rotary tool 16 in the direction of the arrow A2 after placing the workpiece 10 on the receiving tool 17 can also be adopted.

  The friction stir welding apparatus 1 is attached to a drive control device (not shown) composed of an articulated robot or the like. The coordinate positions of the rotary tool 16 and the receiving tool 17, the rotational speed (rpm) of the rotary tool 16, the pressure (N), the pressurization time (second), and the like are appropriately controlled by the drive control device. Although not shown in FIG. 1, the friction stir welding apparatus 1 uses a spacer, a clamp, or the like for fixing the work 10 in advance and preventing the metal member 11 from floating when the rotary tool 16 is pressed. A jig is provided.

(2) Joining method The joining method of the metal member and the resin member by the friction stir welding method according to the present invention is at least the following steps:
A first step of superimposing the metal member 11 and the resin member 12; and while rotating the rotary tool 16, the metal member 11 is pressed to generate frictional heat, and the resin member 12 is softened and melted by the frictional heat. Then, the second step of solidifying and joining the metal member 11 and the resin member 12:
Is included.

First step:
In the first step, as shown in FIG. 1, the metal member 11 and the resin member 12 are overlapped at a desired joint portion.

Second step:
In the present invention, in the second step, the resin member 12 is softened and melted by pressing the surface of the metal member 11 while rotating the rotary tool 16, and then a predetermined solidification process is performed.

(Solidification process)
In the solidification step, first, the rotation of the rotary tool 16 is stopped, but the pressing by the rotary tool 16 is continued even after the rotation of the rotary tool 16 is stopped. As a result, the rotating tool 16 whose rotation has stopped is cooled while achieving the press-clamping of the metal member 11 and the resin member 12, so that the spring back can be sufficiently prevented and the bonding strength is improved. The press-clamping is a pressurizing process for generating a compression action on the resin member 12 by applying pressure. Even if the reinforcing fiber is released from the restraining force of the resin component due to the melting of the resin component in the resin member in the second step, in this step, the resin member 12 is compressed by the pressing by the rotating tool 16 whose rotation is stopped. Therefore, the deformation of the reinforcing fibers is suppressed, and the compression action on the resin member 12 is continued until the molten resin component is solidified, so that the spring back can be sufficiently prevented. When the pressing on the metal member is finished and the metal member is separated from the metal member while the rotary tool is rotated, a springback occurs in the melting region of the resin member 12 released from the compression action.

  The pressure applied by the rotary tool 16 whose rotation has been stopped is set from the viewpoint of preventing springback and avoiding excessive pressurization, and the value is usually 5 to 500 N, preferably 10 to 300 N. This pressing force is a total pressing force necessary to prevent the spring back of the region where the resin member 12 is melted by a series of processes, that is, the region where the spring back of the resin member 12 can occur. Do not stop by. For this reason, the pressing force per unit area of the pressing region that varies depending on the shape of the pressing member is not defined. The applied pressure during this step is usually constant, but may vary within the above range.

  The pressing by the rotating tool 16 whose rotation has been stopped is pressed by the rotating tool 16 on the surface of the metal member 12 when the melting point of the resin member 12 is Tm (° C.) from the viewpoint of further sufficiently preventing the springback. The temperature at the interface between the metal member 11 and the resin member 12 immediately below the region (≈the temperature of the molten region of the resin member 12) is less than Tm, preferably Tm-100 to Tm-10 ° C., more preferably Tm-100 to Tm. It is preferable to carry out until it reaches −20 ° C. In other words, after the interface temperature between the metal member 11 and the resin member 12 is lowered to the above temperature range, it is preferable to end the pressing by the rotary tool 16. If the interface temperature between the metal member 11 and the resin member 12 at the end of pressing by the rotary tool 16 is too high, springback cannot be prevented sufficiently.

  In the present invention, the interface temperature between the metal member 11 and the resin member 12 measured immediately after the end of pressing by the rotary tool 16, that is, immediately after the rotary tool 16 is separated from the metal member 11, may be within the above temperature range.

  The pressing time by the rotating tool 16 whose rotation has been stopped depends on the thickness of the metal member 11 and the type of material, the thickness of the resin member 12 and the type of material, the shape of the rotating tool 16, the type of material, etc. It cannot be determined. The pressing time by the rotating tool 16 whose rotation is stopped is the time from the time when the rotation of the rotating tool 16 is stopped until the time when the rotating tool 16 leaves the metal member 11.

  While the pressing by the rotary tool 16 is continued in the solidification step, it is preferable to forcibly cool the rotating tool 16 or the vicinity of the pressing surface 111 of the metal member 11. By this method, a decrease in the interface temperature between the metal member 11 and the resin member 12 is promoted, and the pressing time by the rotary tool 16 can be shortened, that is, a series of joining processes can be shortened. An example of the cooling method is a method of blowing an air flow.

  After performing the solidification step, that is, after the rotary tool 16 is separated from the metal member 11 and the pressing by the rotary tool 16 is finished, the cooling is usually performed to room temperature. The cooling method is not particularly limited, and examples thereof include a standing cooling method and an air cooling method.

  In the solidification process, prior to stopping the rotation of the rotary tool, the pressure is reduced to 5 to 80%, preferably 10 to 60% of the value immediately before the stop, together with the number of rotations as necessary. It is preferable to carry out the treatment. By such a pressure relaxation process, adhesion of the metal member 11 to the rotary tool 16 after the rotation of the rotary tool is stopped can be prevented.

  The value immediately before serving as a reference for lowering the pressure and the number of rotations is the pressure applied to the metal member 11 by the rotary tool 16 set immediately before the pressure relaxation process and the number of rotations. When the step is an indentation stirring step C2 to be described later, the applied pressure and the rotation speed are set in the indentation stirring step C2, and when the immediately preceding step is an agitation maintaining step C3 to be described later, the agitation maintaining step The pressing force and the rotational speed set in C3.

  In the second step, prior to the solidification step, at least a pushing agitation step C2 in which the rotary tool 16 is pushed into the metal member 11 to enter a depth that does not reach the joining boundary surface 13 between the metal member 11 and the resin member 12 is performed. Preferably it is done.

In the second step, it is preferable to perform a preheating step C1 for rotating the rotary tool 16 in a state where only the tip portion of the rotary tool 16 is in contact with the surface portion of the metal member 11 before the pushing and stirring step. It does not necessarily have to be done.
After the indentation stirring step and before the solidification step, a stirring maintaining step C3 is performed in which the rotary tool 16 continues to rotate at a position where the rotary tool 16 has entered to a depth that does not reach the joining boundary surface. Although it is preferable, this step is not necessarily performed.
Each step in the present invention may be performed by controlling the pressing force (pressing force) and pressing time of the rotating tool, and the amount of movement of the rotating tool in the pressing direction (to the bonding member after contacting the bonding member) The amount of insertion) and the movement time thereof may be controlled.

  Hereinafter, these steps will be described in detail.

(Preheating process C1)
In the preheating step C1, by bringing the rotary tool 16 and the receiving member 17 close to each other, as shown in FIG. 3, only the tip of the rotary tool 16 is placed on the surface portion (upper surface portion in the illustrated example) of the metal member 11. This is a step of rotating the rotary tool 16 in a contacted state. In the preheating step C1, the rotary tool 16 is rotated at a predetermined rotation speed (for example, 3000 rpm) for a first pressurizing time (for example, 1.00 seconds) with a first pressure (for example, 900 N).

  Specifically, in the preheating step C <b> 1, frictional heat is generated at the surface portion (upper surface portion in the illustrated example) of the metal member 11 by pressing of the rotary tool 16. The frictional heat is transmitted to the inside of the metal member 11, and the range of the pressing area P (the pressing area by the rotary tool 16) of the metal member 11 and the area in the vicinity of the pressing area P are preheated. Thereby, it becomes easy to push the rotary tool 16 into the metal member 11 in the next pushing and stirring step C2.

  The first pressurizing force and the first pressurizing time in the preheating step C1 are from the viewpoint of productivity in addition to the ease of pushing the rotary tool 16 and the ease of softening and melting of the resin member 12 as described above. The value is set and varies depending on, for example, the number of rotations of the rotary tool 16, the thickness of the metal member 11, the type of material, and the like. For example, when the aluminum alloy metal member 11 having a thickness of 1 mm or more and 2 mm or less is used, the first pressing force in the preheating step C1 is preferably a value of 700 N or more and less than 1200 N. The first pressurizing time is preferably 0.5 seconds or more and less than 2.0 seconds. The number of rotations of the rotary tool is preferably 2000 rpm or more and 4000 rpm or less.

(Indentation stirring step C2)
In the pushing and stirring step C2, the rotating tool 16 and the receiving member 17 are brought close to each other, thereby pushing the rotating tool 16 into the metal member 11 as shown in FIG. When the indentation stirring step C2 is performed after the preheating step C1, the rotary tool 16 and the receiving member 17 are brought closer to each other, thereby pushing the rotary tool 16 into the metal member 11 as shown in FIG. Thereby, the rotary tool 16 is advanced to a depth that does not reach the joint boundary surface 13 between the metal member 11 and the resin member 12. At this time, it is preferable that the lower part 110 of the metal member 11 is protruded and deformed toward the resin member 12 as shown in FIG. Thereby, about the molten resin 121 of the resin member surface melt | dissolved in the area | region directly under a rotating tool, the fusion | melting and the flow (arrow direction of FIG. 4) to the outer periphery area | region can be accelerated | stimulated.

  Specifically, in the indentation stirring step C2, the rotary tool 16 is moved at a second pressurizing time (for example, 1500 N) that is larger than the first pressurizing time and shorter than the first pressurizing time (for example, Rotate at a predetermined rotation speed (for example, 3000 rpm) for 0.25 seconds.

  In the indentation stirring step C2, the rotating tool 16 is pushed into the metal member 11 when the applied pressure is larger than that in the preheating step C1. That is, the rotary tool 16 enters deep inside the metal member 11. Preferably, when the rotary tool 16 is pressed, the joining boundary surface 13 between the metal member 11 and the resin member 12 moves to the support 17 side (lower side in the illustrated example) in the lower portion 110 of the metal member 11. The right lower part 110 projects and deforms toward the resin member 12 side. As a result, melting of the molten resin 121 on the surface of the resin member melted in the region immediately below the rotary tool at the joining boundary surface 13 is promoted, and flows beyond the region directly below to the outer peripheral region (see FIG. 4). Arrow direction). The molten resin spreads in a substantially circular shape centering on the region directly under the rotary tool. As a result, the contact area between the molten resin and the metal member 11 is expanded, and the melted and solidified region (bonding region) formed by solidifying the molten resin by cooling in the obtained bonded body is also expanded. Can be achieved with sufficiently good working efficiency and sufficient strength.

  If the rotary tool 16 is further pushed in (that is, if the applied pressure is too high and / or the pressurizing time is too long), the shoulder portion 16b of the rotary tool 16 exceeds the joining boundary surface. That is, the rotary tool 16 penetrates the metal member 11, and the outer peripheral portion of the rotary tool 16 contacts the resin member 12. Then, the metal member 11 is in a holed state in which the hole through which the rotary tool 16 has passed is opened, resulting in poor bonding.

  Therefore, in this indentation stirring step C2, the indentation of the rotation tool 16 is stopped when the shoulder portion 16b of the rotation tool 16 enters a depth that does not reach the joint boundary surface. In other words, the rotary tool 16 is advanced to a depth that does not reach the joint interface. As a result, in the next agitation maintaining step C3, frictional heat is generated at a reference position close to the resin member 12, a large amount of frictional heat is transmitted to the resin member 12, and softening and melting of the resin member 12 are promoted.

  The second pressing force and the second pressurizing time in the indentation stirring step C2 are set from the viewpoint of avoiding the opening of the metal member 11 as described above and the rotating tool 16 as close to the resin member 12 as possible. The value varies depending on, for example, the number of rotations of the rotary tool 16, the thickness of the metal member 11, the type of material, and the like. For example, when the aluminum alloy metal member 11 having a thickness of 1 mm or more and 2 mm or less is used, the second applied pressure in the indentation stirring step C2 is preferably a value of 1200 N or more and less than 1800 N. The second pressurization time is preferably 0.1 seconds or more and less than 0.5 seconds. The number of rotations of the rotary tool is preferably 2000 rpm or more and 4000 rpm or less.

(Stirring maintenance step C3)
The agitation maintaining step C3 stops the mutual approach between the rotary tool 16 and the receiving member 17 and, as shown in FIG. This is a step of continuing the rotation operation of the rotary tool 16 at the “position”). In the agitation maintaining step C3, the rotary tool 16 is moved to a third pressurization time (for example, 6.75) longer than the first pressurization time with a third pressurization force (for example, 500 N) smaller than the first pressurization force. Seconds) at a predetermined rotation speed (for example, 3000 rpm).

  In the stirring maintaining step C3, the rotating tool 16 is substantially maintained at the reference position by the applied pressure being smaller than that of the preheating step C1 (of course, being smaller than the pushing stirring step C2). Since the rotary tool 16 continues to rotate at the reference position close to the resin member 12, a large amount of frictional heat is generated, and most of the generated frictional heat moves to the resin member 12. Therefore, the resin member 12 is sufficiently softened and melted over a wide range beyond the range of the region immediately below the pressing region P.

  The third pressing force and the third pressurizing time in the stirring maintaining step C3 are set from the viewpoint of sufficient softening / melting and productivity in a wide range of the resin member 12 as described above, and the values thereof are, for example, It changes depending on the number of rotations of the rotary tool 16, the thickness of the metal member 11, the type of material, and the like. For example, when the aluminum alloy metal member 11 having a thickness of 1 mm or more and 2 mm or less is used, the third pressing force in the stirring and maintaining step C3 is preferably a value of 100 N or more and less than 700 N. The third pressurizing time is preferably a value of 1.0 second or more and less than 20 seconds, particularly a value of 3.0 seconds or more and 10 seconds or less. The number of rotations of the rotary tool is preferably 2000 rpm or more and 4000 rpm or less.

(3) Resin member The resin member 12 used in the joining method of the present invention contains a thermoplastic polymer and reinforcing fibers.

As the thermoplastic polymer constituting the resin member 12, any polymer having thermoplasticity can be used. Of these, thermoplastic polymers used in the field of automobiles are preferably used. Specific examples of such thermoplastic polymers include, for example, the following polymers and mixtures thereof:
Polyolefin resins such as polyethylene and polypropylene and acid-modified products thereof;
Polyester resins such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polylactic acid (PLA);
Polyacrylate resins such as polymethyl methacrylate resin (PMMA);
Polyether resins such as polyether ether ketone (PEEK) and polyphenylene ether (PPE);
Polyacetal (POM);
Acrylonitrile-butadiene-styrene copolymer resin (ABS);
Polyphenylene sulfide (PPS);
PA6, PA66, PA11, PA12, PA6T, PA9T, MXD6 and other polyamide-based resins (PA);
Polycarbonate resin (PC);
Polyurethane resin;
A fluoropolymer resin; and a liquid crystal polymer (LCP).

  As the thermoplastic polymer constituting the resin member 12, a polyolefin resin, particularly polypropylene, which is inexpensive and excellent in mechanical properties is preferably used.

  The molecular weight of the thermoplastic polymer is not particularly limited. For example, the molecular weight may be such that the MFR (melt flow rate value) at 230 ° C. is 2 to 200 g / 10 minutes, particularly 2 to 55 g / 10 minutes. .

  In this specification, the value measured by JIS K 7210 is used for the MFR of the polymer.

  The resin member 12 has a substantially flat plate shape as an overall shape in FIG. 1 and the like, but is not limited to this. When the resin member 12 is overlapped with the metal member 11 for bonding, the resin member 12 is directly below the metal member 11. As long as the portion has a substantially flat plate shape, it may have any shape.

  The thickness t (thickness before joining treatment; see FIG. 3) of the portion immediately below the metal member 11 in the resin member 12 is usually 2 to 10 mm, particularly 2 to 5 mm, but is not limited thereto.

  The reinforcing fiber contained in the resin member 12 is a fiber contained in the polymer in order to improve strength in the field of polymer-containing composite materials, and is generally classified into continuous fibers and discontinuous fibers. In the present invention, the reinforcing fiber particularly means a discontinuous fiber. This is because discontinuous fibers are considered to be prone to spring back, and in the present invention, even when such discontinuous fibers are contained, spring back can be sufficiently prevented.

  The reinforcing fibers are contained in the resin member in a randomly oriented form, and the average fiber length is usually 50 mm or less, particularly 0.1 to 50 mm, preferably 1 to 50 mm. The average fiber diameter of the reinforcing fibers is not particularly limited, and is, for example, 2 to 20 μm, preferably 6 to 15 μm. The type of reinforcing fiber is not particularly limited, and examples thereof include carbon fiber and glass fiber.

  The content of the reinforcing fiber is usually 1% by weight or more, particularly 10 to 50% by weight, preferably 20 to 50% by weight, more preferably 30 to 50% by weight, based on the total amount of the resin member.

  As the content of the reinforcing fiber, a value based on the amount of each material used at the time of manufacturing the resin member can be used, and a value measured by the following method can also be used. First, the resin member is heated by an electric furnace or the like above the decomposition temperature of the thermoplastic polymer and below the decomposition temperature of the reinforcing fiber, thereby removing the thermoplastic polymer and taking out only the reinforcing fiber. By measuring the weight before and after heating, the content of reinforcing fibers can be calculated as a ratio to the weight before heating. Alternatively, the content can be measured by measuring the specific gravity.

  The resin member 12 may further contain additives other than reinforcing fibers, such as stabilizers, flame retardants, colorants, foaming agents, and the like.

  The resin member 12 can be manufactured by subjecting a mixture containing a thermoplastic polymer and reinforcing fibers and a desired additive to a molding method such as an injection molding method or a press molding method.

The melting point Tm of the resin member 12 varies depending on the type of the resin member 12, and is usually 130 to 350 ° C.
As the melting point Tm of the resin member 12, a value measured according to JIS 7121 is used.

(4) Metal member Although the metal member 11 has a substantially flat plate shape as an overall shape in FIG. 1 and the like, it is not limited to this, and only the portion that overlaps the resin member 12 for bonding is provided. As long as it has at least a substantially flat plate shape, it may have any shape.

  The thickness T (thickness before the bonding treatment; see FIG. 3) of the substantially flat plate-shaped portion that overlaps the resin member 12 in the metal member 11 is usually 0.5 to 4 mm, but is not limited thereto.

As the metal constituting the metal member 11, any metal having a melting point higher than that of the thermoplastic polymer constituting the resin member 12 can be used. Among these, the following metals and alloys used in the automotive field are preferably used:
aluminum;
Aluminum alloys such as 5000 series and 6000 series;
steel;
Magnesium and its alloys;
Titanium and its alloys.

[Example 1]
(Resin member)
A resin member 12 having dimensions of 100 mm in length, 30 mm in width, and 3 mm in thickness was produced by an injection molding method using polypropylene pellets containing 40% by weight of carbon fibers (PP-CF40-11; manufactured by Daicel Polymer Co., Ltd.). In the resin member, the average fiber length of the carbon fibers was 3 mm, and the average fiber diameter was 7 μm. The melting point Tm of the resin member was 170 ° C.

(Metal member)
As the metal member, a flat plate member (thickness: 1.2 mm) made of a 6000 series aluminum alloy was used.
(Rotation tool)
As the rotating tool, a tool made of tool steel having dimensions of each part in FIG. 2 of D1 = 10 mm, D2 = 2 mm, and h = 0.5 mm was used.

(Joining method)
The joined body of the metal member 11 and the resin member 12 was manufactured by the following method.
First step:
The end of the metal member 11 and the end of the resin member 12 were overlapped as shown in FIG.

Second step:
First, as shown in FIG. 3, the rotary tool 16 was rotated in a state where only the tip portion of the rotary tool 16 was in contact with the surface portion of the metal member 11 (preheating step C1: pressure 900N, pressurization time 1. 00 seconds, tool rotation speed 3000 rpm).

Thereafter, as shown in FIG. 4, the rotary tool 16 was pushed into the metal member 11 to a depth not reaching the joining boundary surface 13 between the metal member 11 and the resin member 12 (pushing stirring step C2: pressure 1500N, (Pressurization time 0.25 seconds, tool rotation speed 3000 rpm).
Next, as shown in FIG. 4, the rotation operation of the rotary tool 16 was continued at a position where the rotary tool 16 was advanced to a depth that did not reach the joining boundary surface 13 (stirring maintenance step C3: pressurizing force 500 N, pressurization) (Time 6.75 seconds, tool rotation speed 3000 rpm).

  Next, after the rotation of the rotary tool 16 is stopped and the rotation of the rotary tool is stopped, the pressing on the surface of the metal member 11 by the rotary tool is continued with a predetermined pressure as shown in FIG. 4 (solidification process: (Pressure 200N, pressurization time 10 seconds). Immediately after the elapse of a predetermined pressurizing time, pressing by the rotary tool 16 was terminated, and the rotary tool 16 was separated from the metal member 11 as shown in FIG.

(Joint strength)
As shown in FIG. 6, the joined body of the metal member 11 and the resin member 12 was placed in the jig 100. The jig 100 is configured such that a downward force acts on the upper end portion of the resin member 12 by pulling the jig 100 downward. By fixing the jig 100 and pulling the metal member 11 upward, a downward force acts on the upper end portion of the resin member 12, and the shear strength of the joint portion is not affected by the strength of the base material of the resin member 12. S was measured.
A: 4.00 ≦ S;
○: 3.00 ≦ S <4.00 (no problem in practical use);
X: S <3.00.

(Measurement)
The interface temperature (rotational axis position of the rotary tool 16) between the metal member 11 and the resin member 12 immediately after the end of pressing by the rotary tool 16 was measured with a K-type thermocouple.

[Examples 2-7 and Comparative Examples 1-2]
A resin member and a metal member were joined and evaluated by the same method as in Example 1 except that the process conditions were changed as described in the table.
When the pressure relaxation process is performed in the solidification process, after the process C3 and before the rotation of the rotary tool 16, the pressing force is reduced to a predetermined value to rotate the rotary tool 16 at a predetermined rotational speed. Continued for hours.
In Examples 6 and 7, after the rotation of the rotary tool 16 is stopped in the solidification process, while the pressing of the rotary tool on the surface of the metal member 11 is continued, the tip of the rotary tool 16 and the vicinity of the contact portion with the metal member 11 are used. Then, an air flow having a temperature of 25 ° C. was blown at a predetermined flow rate.
In Comparative Examples 1 and 2, at the end of Step C3, the rotary tool 16 was kept rotating and separated from the metal member 11.

  The joining method according to the present invention is useful for joining a metal member and a resin member in the fields of automobiles, railway vehicles, aircraft, home appliances, and the like.

1: Friction stir welding apparatus 10: Workpiece 11: Metal member 12: Resin member 13: Joining interface between metal member and resin member 16: Rotating tool 17: Receiving tool 100: Jig for measuring joint strength 110: Directly below the rotating tool of the metal member 111: Push-in surface 121: Molten resin melted in the region immediately below the rotating tool

Claims (12)

Thermo-pressure bonding in which a metal member and a resin member containing reinforcing fibers are superposed, heat and pressure are locally applied by pressing from the metal member side by the pressing member, and the resin member is softened and melted and then solidified A method of joining a metal member and a resin member by a method,
A method for joining a metal member and a resin member, comprising: a solidification step in which the solidification is performed by continuing the pressing by the pressing member even after the application of heat by the pressing member is stopped.   When the melting point of the resin member is Tm (° C.), in the solidification step, until the interface temperature between the metal member and the resin member immediately below the region pressed by the press member becomes less than Tm (° C.), The joining method of the metal member and resin member of Claim 1 which continues a press.   In the solidification step, prior to stopping the application of heat by the pressing member, a pressure relaxation process is performed in which the pressure is reduced to a value of 5 to 80% of the previous pressure and the rotary tool is rotated. The joining method of the metal member and resin member of description. A first step of superposing the metal member and the resin member; and while rotating the rotary tool, the metal member is pressed against the metal member to generate frictional heat. The resin member is softened and melted by the frictional heat and then solidified. A method of joining a metal member and a resin member by a friction stir welding method including a second step of joining the metal member and the resin member,
The method of joining a metal member and a resin member, wherein the second step includes a solidification step of continuing the pressing by the rotary tool even after the rotation of the rotary tool is stopped and performing the solidification.   When the melting point of the resin member is Tm (° C.), in the solidification step, until the interface temperature between the metal member and the resin member immediately below the region pressed by the rotary tool becomes less than Tm (° C.), The joining method of the metal member and resin member of Claim 4 which continues a press.   6. The pressure relaxation process for rotating the rotary tool by reducing the applied pressure to a value of 5 to 80% of the immediately preceding applied pressure prior to stopping the rotation of the rotary tool in the solidification step. Joining method of metal member and resin member.   The said 2nd step is further provided with the pushing stirring process which pushes the said rotary tool into a metal member before the said solidification process, and makes it approach to the depth which does not reach the joining interface of a metal member and a resin member. The joining method of the metal member and resin member in any one of 4-6.   The said 2nd step is further equipped with the preheating process which rotates a rotary tool in the state which made only the front-end | tip part of the said rotary tool contact the surface part of the metal member before the said pushing stirring process. Joining method of metal member and resin member. In the preheating step, the rotary tool is rotated by a first pressurizing time while being pressed with a first pressing force,
9. The method according to claim 8, wherein in the indentation stirring step, the rotary tool is rotated by a second pressurization time shorter than the first pressurization time while pressing the rotary tool with a second pressurization force larger than the first pressurization force. A method of joining a metal member and a resin member. Stirring in which the rotation of the rotary tool is continued at a position where the second step is after the indentation stirring step and before the solidification step, so that the rotary tool enters a depth not reaching the joining boundary surface. A maintenance process,
The said stirring maintenance process WHEREIN: It rotates only for 3rd pressurization time longer than the said 1st pressurization time, pressing the said rotary tool with the 3rd pressurization force smaller than the said 1st pressurization force. A method of joining a metal member and a resin member.   The joining method of the metal member and resin member in any one of Claims 1-10 in which a reinforced fiber has an average fiber length of 0.1-50 mm.   The joining method of the metal member and resin member in any one of Claims 1-11 in which a resin member contains a reinforcement fiber in the ratio of 10 to 50 weight% with respect to this resin member whole quantity.

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