JP2018140444A - Point joining tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide frictional agitation point joining tool that prevents separation of two metal plates near a junction, securely obtains joining strength required at the junction and, moreover, is easy to handle on a manufacturing management.SOLUTION: A pin 3 side end face of a tool body 1 is a recessed face 2a gradually decreasing in diameter toward the other end, in a longitudinal direction, of the tool body 1. A portion where the side surface of the pin 3 is continuous with the tool body 1 is provided with a curved diameter-increasing part 3c increasing in diameter while gradually curving toward the tool body 1. The shape of the curved diameter-increasing part 3c is set such that when both metal plates 4, 5 are softened by frictional heat and welded, a softened metal portion 7b softened by the frictional heat forms a foamy flow that flows in a direction away from the pin 3 along the curved diameter-increasing part 3c, then, moves toward a first metal plate 4, and returns to the curved diameter-reducing part 3c along a side surface of the pin 3.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a spot welding tool used when performing friction stir spot welding.

  Conventionally, point joining by friction stirring is known as one method for joining superposed metal plates to each other. For this friction stir spot welding, a dedicated tool is used. For example, the spot welding tool disclosed in Patent Document 1 has a rod-shaped tool body and a pin projecting on the axial center of one end in the longitudinal direction of the tool body. Have. Then, the tool body is rotated around the axis with the protruding end of the pin facing the first metal plate side of the superimposed first and second metal plates, and the pin side of the tool body in the rotated state is moved to the first side. The two metal plates are agitated with frictional heat by being pushed into one metal plate, and are solid-phase bonded to each other.

  By the way, the end surface on the pin side in the tool body of Patent Document 1 has a flat shape, and when the friction stir spot welding is performed using this point joining tool, the vicinity of the joint portion between the first and second metal plates. It is generally known that deformation occurs in which the first metal plate is separated from the second metal plate.

  In order to avoid this, for example, in the point joining tool of Patent Document 2, the end surface on the pin side of the tool main body is a concave surface that gradually decreases in diameter as it goes to the other end in the longitudinal direction. By doing so, the first metal plate is pushed into the second metal plate side at the peripheral portion of the concave surface at the time of point joining, and the first metal plate is deformed away from the second metal plate in the vicinity of the joining portion. Can be suppressed.

JP 2010-23068 A JP 2005-161382 A

  However, if the concave surface of the tool body is pushed too much into the first metal plate, the peripheral portion of the concave surface becomes too close to the second metal plate, and the thickness of the joint portion at that portion decreases. Then, even if a joint portion having a joint diameter necessary for quality control is formed between both metal plates, a crack or breakage occurs in a portion where the thickness of the joint portion is reduced due to a load applied to the joint portion. There is a fear. Therefore, it is necessary to set the joining conditions severely so that excessive reduction in the plate thickness does not occur at the joint, which is complicated in production management.

  The present invention has been made in view of such a point, and the object of the present invention is to ensure that the two metal plates are not separated in the vicinity of the joint, and the necessary joint strength is obtained in the joint. It is possible to provide a friction stir spot welding tool that is easy to handle in production management.

  In order to achieve the above object, the present invention is characterized in that the combination of the dimension of the concave surface and the dimension of the pin in the tool body has been devised.

  Specifically, a rod-shaped tool main body and a pin projecting on an axial center at one end in the longitudinal direction of the tool main body are provided, and the first and second metal plates overlap with each other on the first metal plate side. The tool body is rotated about its axis with the protruding ends facing each other, and the two metal plates are agitated by frictional heat by pushing the pin side of the tool body into the metal plates, thereby solidifying each other. The following solution was taken for the point joining tool to be joined.

  That is, in the first invention, the end surface on the pin side of the tool body is a concave surface that gradually decreases in diameter toward the other end in the longitudinal direction of the tool body. The continuous portion is provided with a curved enlarged portion that gradually increases in diameter as it approaches the tool body, and the curved enlarged portion is formed when the two metal plates are welded by softening with frictional heat. The softened metal portion softened by the frictional heat flows in the direction away from the pin along the curved enlarged diameter portion, and then moves to the first metal plate side, along the side surface of the pin. It is set in the shape which forms the spiral flow which returns to a curved enlarged diameter part, It is characterized by the above-mentioned.

  According to a second invention, in the first invention, the protruding end of the pin is provided with a curved surface portion that gradually decreases in diameter as it is separated from the tool body, and a male screw connected to the curved surface portion is provided on a side surface of the pin. A portion is formed.

  According to a third invention, in the first or second invention, the concave surface is formed in a portion excluding an outer peripheral edge portion on an end surface on the pin side of the tool main body.

  In the present invention, in both metal plates, a part of the softened metal portion pushed away by the pin stays in the space formed by the concave surface, so that the first metal plate is interposed via the softened metal portion remaining in the space. On the other hand, a force toward the second metal plate is applied. As a result, the first metal plate is separated from the second metal plate in the vicinity of the joint between the first metal plate and the second metal plate even if the point joining tool is not pushed more than necessary into both metal plates. Can be prevented. In addition, even if the point joining tool is not pushed into both metal plates more than necessary, the joint thickness can be maintained and a joint having the necessary joint strength can be obtained. Therefore, for example, it is not necessary to severely manage joining conditions such as a pressing force, and handling is easy in production management.

  Further, at the time of point joining, after the softened metal portion pushed away by the pin passes through the side of the pin, it smoothly moves to the concave surface of the tool body by the curved enlarged diameter portion. This increases the momentum of the flow of the softened metal portion toward the second metal plate while leaving the pin by the concave surface, and more efficiently mixes the softened metal portion of the first metal plate and the softened metal portion of the second metal plate. Can be made. Further, the force for directing the first metal plate toward the second metal plate increases, so that the first and second metal plates can be prevented from being reliably separated in the vicinity of the joint.

  In particular, in the second invention, at the time of point joining, the softened metal portion in each metal plate is smoothly guided to the side of the pin by the curved surface portion, and flows intensely by the male screw portion on the side surface of the pin. . Therefore, the softened metal portion of the first metal plate and the softened metal portion of the second metal plate can be efficiently mixed in a short time, and the joining time can be shortened.

It is a front end side view of the tool for point joining concerning an embodiment of the present invention. It is a figure which shows the state just before a joining start in the procedure of carrying out the point joining of the two metal plates of a polymerization state using the tool for point joining which concerns on embodiment of this invention. It is a figure which shows the state immediately after starting the joining by making the tool for point joining approach a metal plate after the state of FIG. It is a figure which shows the state in the middle of joining by pushing the tool for point joining into the metal plate of a superposition | polymerization state after the state of FIG. (A) is a figure which shows the state in the middle of joining by pushing the tool for point joining into the superposition | polymerization state metal plate after the state of FIG. 4, (b) is A of (a). FIG. (A) is a figure which shows the state in the middle of joining by pushing the tool for point joining into the metal plate of a superposition | polymerization state after the state of FIG. 5, (b) is a figure of B of (a). FIG. It is a figure which shows the state just before ending a joining after pushing the tool for point joining into the metal plate of a superposition | polymerization state after the state of FIG. It is a figure which shows the state immediately after finishing the joining after separating the point joining tool from the polymerization state metal plate after the state of FIG. (A) is a front view of the tip side of a conventional friction stir spot welding tool A, and (b) is a front view of the tip side of conventional friction stir spot welding tools B and C. The experimental result in the point joining tool which concerns on embodiment of this invention, and the conventional point joining tools A and B is shown. The experimental result in the tool for point joining which concerns on embodiment of this invention, and the tool C for conventional point joining is shown. (A) is a cross section of the joint part joined by the point joining tool according to the embodiment of the present invention, (b) is a cross section of the joint part joined by the conventional point joining tool A, and (c) is a cross section. It is a photograph which shows the cross section of the junction part joined by the conventional tool B for point joining.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The following description of the preferred embodiment is merely exemplary in nature.

  FIG. 1 shows a point joining tool 1 according to an embodiment of the present invention. The point joining tool 1 is used for spot joining the first metal plate 4 and the second metal plate 5 (see FIGS. 2 to 8) that are overlapped with each other by friction stirring, and is attached to a joining device (not shown). Used.

  The point joining tool 1 is integrally formed of hot tool steel (SKD61), and includes a rod-shaped tool body 2 and a pin 3 projecting on an axis C at one end in the longitudinal direction of the tool body 2. And at the time of point joining, it rotates in the X direction around the axis C.

  The end surface of the tool body 2 on the pin 3 side is a concave surface 2 a that gradually decreases in diameter linearly toward the other end in the longitudinal direction of the tool body 2. The concave surface 2a is formed in a portion excluding the outer peripheral edge portion on the end surface of the tool body 2 on the pin 3 side.

  The projecting end of the pin 3 is provided with a curved surface portion 3a that gradually decreases in diameter as the distance from the tool body 2 increases.

  A male screw portion 3b connected to the curved surface portion 3a is formed on the side surface of the pin 3, and the male screw portion 3b is a reverse screw with respect to rotation in the X direction.

  Further, a curved diameter-enlarged portion 3 c that gradually increases in diameter as it approaches the tool body 2 is provided in a continuous portion of the side surface of the pin 3 with the tool body 2.

  Then, the first metal plate 4 and the second metal plate 5 are superposed, and the protruding end of the pin 3 faces the first metal plate 4 side of the superposed first metal plate 4 and second metal plate 5. The tool body 2 is rotated around the axis C, and the metal plates 4 and 5 are softened by frictional heat by pushing the pin 3 side of the tool body 2 into the metal plates 4 and 5. They are designed to be solid-phase bonded to each other.

  Here, in the point joining tool 1, the thickness of the first metal plate 4 is T1 (mm), the thickness of the second metal plate 5 is T2 (mm), and the set joining width Dn (see FIG. 8). ), The diameter of the tool body 2 is Dt (mm), the height Hp (mm) of the pin 3, the diameter Dp (mm) of the pin 3, and the depth of the concave surface 2a (of the concave surface 2a). The longitudinal dimension (L) (mm) in the tool body 2 was set based on the following idea.

  That is, the softened metal portion 7b softened by frictional heat in the first and second metal plates 4 and 5 moves while being agitated by the pin 3, but as shown in FIG. The more the portion 7b moves to the area outside the outer peripheral surface of the tool body 2, the thinner the joint 7 becomes. Therefore, it was considered that the softened metal portion 7b in the region Ra pushed away by the pin 3 should be kept in the region Rb formed by the concave surface 2a as much as possible in order to keep the thickness of the joint 7 thick.

  On the other hand, in order to suppress the deformation in which the first metal plate 4 is separated from the second metal plate 5 in the vicinity of the joint portion 7 between the first and second metal plates 4 and 5, the first metal plate 4 is formed at the peripheral portion of the concave surface 2a. However, the present invention is not limited to this, and the concave metal surface 7b of the region Ra that is pushed away by the pin 3 moves laterally toward the region Rb after moving the side of the pin 3 toward the region Rb. The deformation in which the first metal plate 4 is separated from the second metal plate 5 can also be suppressed by increasing the force Y (see FIG. 7) when moving from the region Rb toward the second metal plate 5 side along 2a. I thought I could do it.

  Therefore, it is considered that a configuration in which half of the softened metal portion 7b of the region Ra remains in the region Rb and the other half moves from the region Rb toward the second metal plate 5 side. A point joining tool 1 was designed.

  In addition, the dimension of Dt was 10 mm which is a standard dimension in friction stir spot welding.

  Further, Dp is generally set to 75% of the set junction width Dn because it is generally known that 75% of the set junction width Dn is an appropriate value.

  Note that the point joining tool 1 is also effective for numerical values whose dimensions vary by about ± 1% due to the processing capability of the tool for processing the point joining tool 1.

  In the embodiment of the present invention, the radius of curvature of the curved surface portion 3a is set to 2.9 mm, and the radius of curvature of the curved enlarged diameter portion 3c is set to 0.6 mm.

  Next, a method for spot joining the first metal plate 4 and the second metal plate 5 that are overlapped with each other with the tool 1 for spot joining will be described.

  First, as shown in FIG. 2, the 1st metal plate 4 and the 2nd metal plate 5 are piled up on the receiving stand 6 so that the 1st metal plate 4 may become an upper side.

  Next, the tool body 2 is brought into a posture in which the pin 3 faces downward (a posture in which the protruding end of the pin 3 faces the first metal plate 4), and the tool body 2 is moved in the X direction at a predetermined rotational speed by a rotation motor (not shown). Rotate.

  Next, the rotated tool body 2 is moved downward to approach the first metal plate 4 and the second metal plate 5.

  Thereafter, as shown in FIG. 3, the protruding end of the pin 3 comes into contact with the surface of the first metal plate 4. Then, the first metal plate 4 starts to be heated from the contact portion K.

  Thereafter, when the tool main body 2 is moved downward, the frictional heat generated between the pin 3 and the first metal plate 4 is transmitted through the first metal plate 4 as shown in FIG. As it expands, the pin 3 enters the softened metal portion 7b.

  Further, when the tool main body 2 is moved downward, as shown in FIGS. 5A and 5B, the flow that rises along the curved surface portion 3a and the male screw portion 3b in the softened metal portion 7b and the male screw portion. The flow around the pin 3 by 3b can be made and the stirring in the softened metal portion 7b is promoted. Further, the speed at which the heated metal portion 7a spreads is increased by promoting the stirring of the softened metal portion 7b.

  Thereafter, when the tool body 2 is further moved downward, as shown in FIGS. 6A and 6B, a partial region of the softened metal portion 7b rising along the curved surface portion 3a and the male screw portion 3b is obtained. The curved enlarged diameter portion 3c flows in a spiral shape. Then, in the softened metal portion 7b, the upward flow made by the curved surface portion 3a and the male screw portion 3b and the spiral flow made by the curved enlarged-diameter portion 3c are mixed to promote stirring of the softened metal portion 7b. At the same time, the spreading speed of the heated metal portion 7a is further increased.

  Further, when the tool body 2 is further moved downward, as shown in FIG. 7, the softened metal portion 7b contacts the entire concave surface 2a, and a spiral flow around the curved enlarged diameter portion 3c occurs in the softened metal portion 7b. In addition to being able to flow, a flow that moves toward the second metal plate 5 along the concave surface 2a while moving away from the pin 3 also occurs.

  Thereafter, the tool main body 2 is pressed into the first metal plate 4 and the second metal plate 5 with a predetermined pressurizing force and maintained for a predetermined time. Thereafter, as shown in FIG. Is moved upward and the softened metal portion 7b is solidified to form the joint 7.

Next, an experiment in which point bonding is performed using the point bonding tool 1 according to the embodiment of the present invention will be described.
-Experiment 1
Using the above-described spot welding tool 1 and tools A and B, two aluminum alloy plates (A5000 series) having a thickness of 1 mm were stacked and spot welding was performed by friction stirring while changing the welding conditions. In addition, each tool dimension, joining conditions, and the quality determination method are shown below. The set bonding width Dn was 4 mm.
<Dimensions for spot welding tool 1>
The diameter Dt of the tool body 2 is set to 10 mm, the height Hp of the pin 3 is set to 1.83 mm, the diameter Dp of the pin 3 is set to 3 mm, and the depth L of the concave surface 2a is set to 0.43 mm. Yes.
<Tool A dimensions>
The diameter Dt of the tool body 2 is set to 10 mm, the height Hp of the pin 3 is set to 1.2 mm, and the diameter Dp of the pin 3 is set to 3 mm. The concave surface 2a has a flat shape.
<Tool B dimension>
The diameter Dt of the tool body 2 is set to 10 mm, the height Hp of the pin 3 is set to 2.0 mm, the diameter Dp of the pin 3 is set to 3 mm, and the depth L of the concave surface 2a is set to 0.6 mm. Yes.
<Joint conditions>
Rotational speed of each tool: The joining condition obtained in the preliminary experiment conducted in advance is set to a management center value of 1500 rpm, and data is acquired at the rotational speed changed by ± 500 rpm from this value.
・ Pressure force of each tool: The joining condition obtained in the preliminary experiment conducted in advance is set as the management center value 4410N, and data is acquired with the pressure force changed by ± 490N from this value.
-Pressurizing time of each tool: Acquire data of pressing time changed by 0.5 s.
<Pass / fail judgment method>
Evaluation α: A case where the surface of the joint portion on the first metal plate 4 side is glossy is marked as ◯, and a case where the surface of the joint portion is rough (when the softened metal portion does not flow well) is marked as x.
Evaluation β: The distance between the first metal plate 4 and the second metal plate 5 in the vicinity of the joint portion was measured.
-Evaluation (gamma): The joint width (joint diameter) between the 1st metal plate 4 and the 2nd metal plate 5 was measured, and the case where it was 4.0 mm or more was set as (circle) and less than 4.0 mm.
<Result of Experiment 1>
FIG. 10 shows the experimental results. For the conditions where the evaluations α to γ are all ◯, colors are given in the figure. As can be seen from this result, the point joining tool 1 of the present invention can make the joining conditions wider than those of the tool A and the tool B.
-Experiment 2-
Using the tool 1 for point joining and the tool C, two aluminum alloy plates (A6000 series) having a thickness of 1.8 mm were stacked, and an experiment was carried out for spot joining by friction stirring while changing the joining conditions. In addition, each tool dimension and joining conditions are shown below. The set bonding width Dn was 5 mm.
<Dimensions for spot welding tool 1>
The diameter Dt of the tool body 2 is set to 10 mm, the height Hp of the pin 3 is set to 2.6 mm, the diameter Dp of the pin 3 is set to 3.75 mm, and the depth L of the concave surface 2a is set to 0.98 mm. doing.
<Tool C dimension>
As shown in FIG. 9B, the diameter Dt of the tool body 2 is 10 mm, the height Hp of the pin 3 is 2.75 mm, the diameter Dp of the pin 3 is 4 mm, and the depth of the concave surface 2a. L is set to 0.8 mm.
<Joint conditions>
-Number of rotations of each tool: The joining condition obtained in the preliminary experiment conducted in advance is set to a management center value of 2500 rpm, and data is acquired at the number of rotations changed by ± 500 rpm from this value.
-Pressurizing force of each tool: The joining condition obtained in the preliminary experiment conducted in advance is set as the management center value 4900N, and data is acquired with the pressing force changed by ± 490N from this value.
-Pressurizing time of each tool: Acquire data of pressing time changed by 0.5 s.
<Pass / fail judgment method>
Evaluation α: A case where the surface of the joint portion on the first metal plate 4 side is glossy is marked as ◯, and a case where the surface of the joint portion is rough (when the softened metal portion does not flow well) is marked as x.
Evaluation β: The distance between the first metal plate 4 and the second metal plate 5 in the vicinity of the joint portion was measured.
Evaluation δ: The bonding width (bonding diameter) between the first metal plate 4 and the second metal plate 5 was measured.
<Result of Experiment 2>
FIG. 11 shows the experimental results. The conditions in which the evaluation α, β, and δ are all ◯ are colored in the figure. As can be seen from this result, compared to the tool C, the point joining tool 1 of the present invention can widen the joining conditions even in the joining with a combination of plate thicknesses different from the experiment 1.

  FIG. 12 shows a cross-section in which two point aluminum alloy plates (A5000 series) having a thickness of 1 mm are spot-bonded using the point bonding tool 1 described above. The Dt of the point joining tool 1 is 10 mm, the height Hp of the pin 3 is 1.83 mm, the diameter Dp of the pin 3 is 3 mm, and the depth L of the concave surface 2a in the tool body 2 in the longitudinal direction is 0.43 mm. The joining conditions were a rotation speed of 1500 rpm, a pressure of 3920 N, and a pressurization time of 1.5 s.

  As can be seen from the result of FIG. 12A, there is no gap between the first metal plate 4 and the second metal plate 5 in the vicinity of the joint portion 7, and the first metal plate 4 has no thickness reduction portion. It has become.

  FIG. 12B shows a cross section in which the tool A is used and two aluminum alloy plates (A5052) having a thickness of 1 mm are overlapped and spot-bonded. The joining conditions were a rotation speed of 1500 rpm, a pressing force of 3920 N, and a pressing time of 1.5 s.

  As can be seen from the result of FIG. 12B, a large gap is generated between the first metal plate 4 and the second metal plate 5 in the vicinity of the joint.

  FIG. 12C shows a cross section in which the tool B is used and two aluminum alloy plates (A5000 series) having a thickness of 1 mm are overlapped and spot bonded. The number of revolutions was 1500 rpm, the applied pressure was 3920 N, and the pressurization time was 1.5 s.

  As can be seen from the result of FIG. 12C, a low-strength portion in which the plate thickness is greatly reduced is generated on the first metal plate 4 side.

As described above, according to the embodiment of the present invention, in the first and second metal plates 4 and 5, the second metal plate 5 side with respect to the first metal plate 4 by the part of the softened metal portion 7 b pushed away by the pin 3. Therefore, even if the point joining tool 1 is not pushed into the first and second metal plates 4 and 5 more than necessary, the force between the first metal plate 4 and the second metal plate 5 is increased. It is possible to prevent the first metal plate 4 from being separated from the second metal plate 5 in the vicinity of the joint 7 therebetween. Further, in the first and second metal plates 4 and 5, part of the softened metal portion 7b pushed away by the pin 3 remains in the space (region R _b ) formed by the concave surface 2a. Even if the tool 1 is not pushed into the first and second metal plates 4 and 5 more than necessary, the thickness of the joining portion 7 is kept thick, and the joining portion 7 having the necessary joining strength is obtained. be able to. Furthermore, since the inclination of the concave surface 2a can be reduced, there is no need to worry about excessive reduction in the thickness of the joint 7 due to the tool shape. Therefore, for example, it is not necessary to severely manage joining conditions such as a pressing force, and handling is easy in production management.

  Further, at the time of point joining, the softened metal portion 7b in each of the metal plates 4 and 5 is smoothly guided to the side of the pin 3 by the curved surface portion 3a, and flows intensely by the male screw portion 3b on the side surface of the pin 3. Become. Therefore, the softened metal portion 7b of the first metal plate 4 and the softened metal portion 7b of the second metal plate 5 can be efficiently mixed in a short time, and the joining time can be shortened.

  Further, during the point joining, the softened metal portion 7b pushed away by the pin 3 passes through the side of the pin 3 and then moves smoothly to the concave surface 2a of the tool body 2 by the curved enlarged diameter portion 3c. The concave surface 2 a increases the momentum in the flow of the softened metal portion 7 b toward the second metal plate 5 while being away from the pin 3, and the softened metal portion 7 b of the first metal plate 4 and the softened metal portion 7 b of the second metal plate 5. Can be mixed more efficiently, and the force for directing the first metal plate 4 toward the second metal plate 5 is increased so that the first and second metal plates 4 and 5 are located in the vicinity of the joint 7. Can be surely not separated.

  The present invention is suitable for a point joining tool used when performing friction stir spot joining.

DESCRIPTION OF SYMBOLS 1 Point joining tool 2 Tool main body 2a Concave surface 3 Pin 3a Curved surface part 3b Male thread part 3c Curve expansion part 4 1st metal plate 5 2nd metal plate 7 Joint part 7b Softening metal part C Axis center

Claims (3)

A rod-shaped tool main body and a pin projecting on the axial center of one end in the longitudinal direction of the tool main body are provided, and the protruding end of the pin faces the first metal plate side of the superimposed first and second metal plates The tool body is rotated around the axis in a posture to be pressed, and the two metal plates are softened by frictional heat by pushing the pin side of the tool body into the both metal plates, and are used for point joining. A tool,
The end surface on the pin side of the tool body is a concave surface that gradually decreases in diameter as it goes to the other end side in the longitudinal direction of the tool body,
The continuous portion of the side surface of the pin with the tool body is provided with a curved diameter-expanding portion that gradually increases in diameter while being closer to the tool body,
When the two metal plates are welded by softening the two metal plates with frictional heat, the softened metal portion softened by the frictional heat flows in a direction away from the pin along the curved widened portion. After that, it is set to a shape that moves to the first metal plate side and forms a spiral flow that returns to the curved enlarged diameter portion along the side surface of the pin. tool. In the point joining tool according to claim 1,
The protruding end of the pin is provided with a curved surface portion that gradually decreases in diameter as it moves away from the tool body, and a male screw portion connected to the curved surface portion is formed on the side surface of the pin. Joining tool. In the point joining tool according to claim 1 or 2,
The point joining tool, wherein the concave surface is formed in a portion excluding an outer peripheral edge portion of an end surface on the pin side of the tool main body.