JP2010023068A - Friction stir welding tool and spot welding method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To ensure the productivity equivalent to that of the conventional friction stir welding while ensuring the strength of a joined part by the friction stir welding by providing a spot welding method for permitting the raise of an upper plate during the welding and adequately limiting the raise by a friction stir welding tool. <P>SOLUTION: The friction stir welding tool 11 includes a columnar body shaft part 12, a shoulder face 12a formed on an end on one side of the body shaft part 12, and a pin part 13 projected on the shoulder face 12a and having a pin part of the diameter smaller than that of the shoulder face 12a, and is used for the point welding of an object to be welded in which a plurality of base plate materials including at least an upper plate and a lower plate are layered. There is provided a raise preventive unit 14 which is projected from an outer circumferential surface of the body shaft part 12 outwardly in the radial direction. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a technology of a friction stir welding tool used when performing spot welding by friction stir welding, and more specifically, a friction stir welding tool capable of preventing an upper plate of a point-joined workpiece from being lifted, and It is related with the technique of the used point joining method.

Conventionally, a technique for performing point joining by friction stir welding is known, and has attracted attention as a new joining technique that replaces spot welding joining and rivet joining.
However, for example, when an object to be joined (for example, an upper plate and a lower plate) is joined by point joining by friction stir welding (friction stir spot joining), there is a problem that the upper plate is deformed and floats in the vicinity of the joining point. . In order to solve this problem, techniques shown in the following Patent Documents 1 to 3 have been developed and are publicly known.

  In these conventional techniques, a pressing means for pressing the vicinity of the joining point of the workpiece is provided, and the vicinity of the joining point is pressed by the pressing means from the stage before the friction stir welding tool is brought into contact with the joining point. In addition, point joining is performed in a state where the upper plate and the lower plate are pressed. This solves the problem that the upper plate floats when performing friction stir spot welding.

These prior arts are based on the idea that the upper plate is not allowed to lift, and the behavior of the upper plate is tightly regulated by the pressing means. However, when the pressing means is pressed in the vicinity of the joining point, the progress of the plastic flow at the joined portion is inhibited, and a new problem has arisen that the time required for joining is increased. For this reason, compared with the conventional friction stir spot joining, productivity will fall significantly and it was difficult to apply the friction stir spot joining using a press means in an actual manufacturing process.
Japanese Patent No. 3516913 Japanese Patent No. 3471317 JP 2003-154472 A

  The present invention has been made in view of the present situation, and by allowing a point joining method that allows the floating of the upper plate during joining and appropriately restricts the amount of lifting by the friction stir welding tool, the friction stir point is provided. By joining, it is making it the subject to ensure the productivity equivalent to the conventional friction stir spot joining, ensuring the intensity | strength of a junction part.

  The problems to be solved by the present invention are as described above. Next, means for solving the problems will be described.

  That is, in claim 1, a cylindrical body shaft portion, a shoulder surface formed at one end of the body shaft portion, and a pin projecting from the shoulder surface and having a smaller diameter than the shoulder surface A friction stir welding tool used for spot joining of an object to be joined formed by laminating a plurality of plate-like materials including at least an upper plate and a lower plate, and a radial direction from an outer peripheral surface of the main body shaft portion It is provided with a lifting prevention portion projecting outward.

  In claim 2, the distance between the lower prevention part and the lower end face of the pin part is a positive value obtained by subtracting the thickness of the object to be joined, and The distance from the lower surface portion to the upper surface of the upper plate when the pin portion is press-fitted to the object to be joined is not more than the maximum allowable lifting amount of the upper plate. It arranges in the position which becomes.

  According to a third aspect of the present invention, a gap portion is formed in the lower surface portion from the outer peripheral surface of the main body shaft portion to the outer peripheral edge portion of the lifting prevention portion.

  According to a fourth aspect of the present invention, the lifting prevention portion is detachable from the main body shaft portion.

  According to a fifth aspect of the present invention, the lifting prevention portion is disposed on the main body shaft portion via a bearing.

  In the present invention, the bearing is a radial bearing.

  In Claim 7, It is a point joining method of the to-be-joined object formed by laminating | stacking the several plate-shaped raw material containing an upper board and a lower board at least, Comprising: A cylindrical main-body axial part and one side of the said main-body axial part A shoulder surface formed at the end of the body, a pin portion protruding from the shoulder surface, a pin portion having a smaller diameter than the shoulder surface, and a lifting prevention portion protruding radially outward from the outer peripheral surface of the body shaft portion A friction stir welding tool comprising: a friction stir welding tool is rotated around the axis of the friction stir welding tool, and is press-fitted into the joint portion of the workpiece from the upper plate side, and the workpiece is joined at the joint portion. On the other hand, in the vicinity of the joint portion, the upper plate is lifted and brought into contact with the lift prevention portion.

  According to an eighth aspect of the present invention, the lifting amount of the upper plate is set to a value equal to or less than the maximum allowable lifting amount of the upper plate.

  In claim 9, when the friction stir welding tool is press-fitted into the joined portion of the workpiece from the upper plate side while rotating around the axis, the lifting prevention portion is separated from the upper plate. It is what.

  As effects of the present invention, the following effects can be obtained.

  According to the first aspect of the present invention, the amount of lifting of the upper plate can be regulated with a simple configuration.

  According to the second aspect of the present invention, the plastic flow in the vicinity of the joint can be surely progressed, and the lifting amount of the upper plate can be appropriately regulated without reducing the productivity.

  According to the third aspect of the present invention, it is possible to prevent the burr from being welded to the floating prevention portion without disturbing the burr formation.

  According to the fourth aspect of the present invention, the floating amount of the upper plate can be easily adjusted. Further, the lifting prevention portion can be used for an existing friction stir welding tool.

  According to the fifth aspect of the present invention, it is possible to prevent the contact portion by the floating prevention portion of the upper plate from being damaged.

  According to the sixth aspect of the present invention, it is possible to prevent the contact portion by the floating prevention portion of the upper plate from being damaged with a simple configuration.

  According to the seventh aspect of the present invention, it is possible to regulate the lifting amount of the upper plate with a simple configuration.

  According to the eighth aspect of the present invention, it is possible to regulate the floating amount of the upper plate without reducing the productivity.

  According to the ninth aspect of the present invention, it is possible to properly regulate the lifting amount of the upper plate without reducing the productivity.

Next, embodiments of the invention will be described.
First, the overall configuration of the friction stir welding apparatus will be described with reference to FIG. FIG. 1 is a schematic diagram showing the overall configuration of the friction stir welding apparatus.
As shown in FIG. 1, the friction stir welding apparatus 1 uses a friction stir welding method to spot-join a workpiece 7 in which a plurality of plate-like members composed of, for example, an upper plate 7 a and a lower plate 7 b are stacked. The apparatus includes a main body 2, a rotating shaft 3, a motor 4, a motor support 5 and the like.

The rotary shaft 3 is rotationally driven by the motor 4 and the motor support portion 5 is supported to be displaceable in the vertical direction with respect to the main body portion 2, whereby the rotary shaft 3 can also be displaced in the vertical direction. It is configured.
A chuck 6 is provided at the lower end of the rotary shaft 3, and a friction stir welding tool 11, which is a tool for friction stir the workpiece 7, is attached to the chuck 6. That is, the friction stir welding apparatus 1 can rotate the friction stir welding tool 11 around the axis and can reciprocate the friction stir welding tool 11 in the vertical (axial) direction. It is said.

  Then, with the workpiece 7 placed on the receiving portion 8, the friction stir welding tool 11 is lowered while rotating, and the friction stir welding tool 11 is pressed against the workpiece 7 to a predetermined depth. By press-fitting and plastically flowing the structure of each material of the workpiece 7 (here, the upper plate 7a and the lower plate 7b) at the press-fitting location, the workpiece 7 (that is, the upper plate 7a and the lower plate 7b). The point is joined.

Next, the overall configuration of the friction stir welding tool according to the first embodiment of the present invention will be described with reference to FIG. FIG. 2 is a schematic diagram showing the overall configuration of the friction stir welding tool according to the first embodiment of the present invention.
As shown in FIG. 2, the friction stir welding tool 11 according to the first embodiment of the present invention includes a main body shaft portion 12, a pin portion 13, a lifting prevention portion 14, and the like.
The main body shaft portion 12 is a substantially cylindrical shaft member, and the upper end portion (not shown) of the main body shaft portion 12 is sandwiched by the chuck 6 so that the friction stir welding tool 11 is attached to the friction stir welding apparatus 1. It is to be attached. Moreover, the shoulder surface 12a is formed in the lower end surface of the main-body shaft part 12, and it is set as the structure which protrudes the pin part 13 smaller diameter than the shoulder surface 12a toward the downward direction from the shoulder surface 12a.

  Screws are formed on the outer peripheral surface of the pin portion 13, and the pin portion 13 is press-fitted while being rotated into the workpiece 7, thereby generating frictional heat in the vicinity of the press-fitted location and joining in the vicinity of the press-fitted location. While the object 7 is softened, it is a site | part which plays the role which plastically flows the softened to-be-joined thing 7 to the axial direction of the friction stir welding tool 11, and a rotation direction by the stirring action which arises with a screw | thread.

  The lifting prevention portion 14 is a collar-like portion that protrudes radially outward from the outer peripheral surface of the main body shaft portion 12, and contacts the lower surface portion 14 a of the lifting prevention portion 14 with the upper plate 7 a that is lifted during joining. By doing so, it becomes a part that plays a role of regulating the floating amount of the upper plate 7a. In the present embodiment, the collar-shaped lifting prevention portion 14 is illustrated, but for example, the lifting prevention is performed by several convex portions projecting radially outward from the outer peripheral surface of the main body shaft portion 12 in the radial direction. It is also possible to constitute the part, and the shape of the lifting prevention part 14 is not limited to the collar shape.

That is, the friction stir welding tool 11 according to the first embodiment of the present invention includes a columnar main body shaft portion 12, a shoulder surface 12a formed at one end of the main body shaft portion 12, and a shoulder surface 12a. A friction stir welding tool 11 used for point joining of an object to be joined 7 formed by laminating a plurality of plate-like materials including at least an upper plate 7a and a lower plate 7b. The structure is provided with a lifting prevention portion 14 projecting outward from the outer peripheral surface of the main body shaft portion 12 in the radial direction.
By adopting such a configuration, it is possible to regulate the lifting amount of the upper plate 7a with a simple configuration.

  Further, a gap portion 14 b is formed in the lower surface portion 14 a of the lifting prevention portion 14 from the main body shaft portion 12 toward the radially outer side. This gap portion 14b is formed between the outer peripheral surface of the main body shaft portion 12 and the outer peripheral edge portion of the floating prevention portion 14, and is a space for allowing the burr 9 generated in the vicinity of the joint portion 7e during joining. By ensuring a space in which the burr 9 can protrude, the burr 9 is prevented from coming into contact with the floating prevention portion 14 and being welded, and the plastic flow in the vicinity of the joint portion 7e is not hindered.

That is, in the friction stir welding tool 11 according to the first embodiment of the present invention, the lower surface portion 14 a of the lifting prevention portion 14 is between the outer peripheral surface of the main body shaft portion 12 and the outer peripheral edge portion of the lifting prevention portion 14. The gap 14b is formed.
By adopting such a configuration, the plastic flow in the vicinity of the joint portion 7e can be reliably advanced without disturbing the formation of the burr 9 and preventing the burr 9 from coming into contact with the rising prevention portion 14 and welding. is there.

Next, the overall configuration of the friction stir welding tool according to the second embodiment of the present invention will be described with reference to FIG. FIG. 3 is a schematic diagram showing the overall configuration of the friction stir welding tool according to the second embodiment of the present invention.
As shown in FIG. 3, the friction stir welding tool 21 according to the second embodiment of the present invention includes a main body shaft portion 22, a pin portion 23, a lifting prevention portion 24, and the like.
The main body shaft portion 22 is a substantially cylindrical shaft member, and the friction stir welding tool 21 is attached to the friction stir welding apparatus 1 by holding the upper end portion (not shown) of the main body shaft portion 22 between the chucks 6. It is to be attached. Further, a shoulder surface 22a is formed on the lower end surface of the main body shaft portion 22, and a pin portion 23 is projected from the shoulder surface 22a downward.

The lifting prevention portion 24 is configured by a base portion 24a and a convex portion 24b, and is configured to be detachable with respect to the main body shaft portion 22. In this respect, unlike the friction stir welding tool 11 according to the first embodiment. Yes.
The base portion 24a is formed in a cylindrical shape and is configured to be able to be inserted through the main body shaft portion 22. The base portion 24a is provided with fixing bolts (or set screws) 24c, 24c,... For fastening the lifting prevention portion 24 to the main body shaft portion 22, and the main body shaft portion 22 is inserted into the base portion 24a. In this state, by fixing the fixing bolts (or set screws) 24c, 24c,..., The floating prevention portion 24 is fixed to the main body shaft portion 22.

  Thereby, the collar-shaped convex part 24b protrudes from the outer peripheral surface of the main-body shaft part 22 toward the radial direction outer side. The upper plate 7a that is lifted at the time of joining is brought into contact with the lower surface portion 24d of the lift preventing portion 24, thereby serving as a part that plays a role in regulating the amount of lifting of the upper plate 7a.

  Moreover, since the lifting prevention part 24 can adjust an attachment position, it can respond to the change of the thickness of the to-be-joined thing 7, etc. FIG. Further, it is possible to divert and mount the anti-lifting portion 24 to an existing friction stir welding tool that does not include the anti-lifting portion.

  Furthermore, a gap portion 24e is formed in the lower surface portion 24d of the lifting prevention portion 24 from the main body shaft portion 22 toward the radially outer side. The gap portion 24e is a space for allowing the burr 9 generated in the vicinity of the bonding portion 7e to enter during bonding. By ensuring a space in which the burr 9 can protrude, the burr 9 comes into contact with the floating prevention portion 24. While preventing welding, it plays a role of preventing the plastic flow in the vicinity of the joint 7e from being hindered.

That is, in the friction stir welding tool 21 according to the second embodiment of the present invention, the lifting prevention part 24 is configured to be detachable from the main body shaft part 22.
By setting it as such a structure, the floating amount of the upper board 7a can be adjusted easily. Further, the lifting prevention unit 24 can be used for an existing friction stir welding tool.

Next, the overall configuration of the friction stir welding tool according to the third embodiment of the present invention will be described with reference to FIG. FIG. 4 is a schematic diagram showing the overall configuration of the friction stir welding tool according to the third embodiment of the present invention.
As shown in FIG. 4, the friction stir welding tool 31 according to the third embodiment of the present invention includes a main body shaft portion 32, a pin portion 33, a lifting prevention portion 34, a bearing 35, and the like.
The main body shaft portion 32 is a substantially cylindrical shaft member, and the friction stir welding tool 31 is attached to the friction stir welding apparatus 1 by sandwiching the upper end portion (not shown) of the main body shaft portion 32 with the chuck 6. Is. Further, a shoulder surface 32a is formed on the lower end surface of the main body shaft portion 32, and a pin portion 33 is projected from the shoulder surface 32a downward.

  The floating prevention portion 34 is disposed on the outer peripheral surface of the main body shaft portion 32 via a bearing 35, and constitutes a collar-like portion protruding from the main body shaft portion 32 toward the outer side in the radial direction. The upper plate 7a that is lifted at the time of joining is brought into contact with the lower surface portion 34a of the lift preventing portion 34, thereby serving as a part that regulates the amount of lifting of the upper plate 7a.

  Since each of the anti-lifting portions 14 and 24 according to the first embodiment and the second embodiment described above is fixed to the main body shaft portions 12 and 22, with the rotation of the main body shaft portions 12 and 22, Each lifting prevention part 14/24 is also configured to rotate. For this reason, the upper plate 7a that has been lifted may be damaged at the portions that contact the lift preventing portions 14 and 24.

  On the other hand, since the lifting prevention portion 34 according to the third embodiment is configured to be disposed on the body shaft portion 32 via the bearing 35, the lifting prevention portion 34 is stationary even when the body shaft portion 32 rotates. It can be maintained. Thereby, when the lifted upper plate 7a comes into contact with the lift preventing portion 34, the contacted portion is prevented from being damaged.

  Note that the reaction force acting in the axial direction received from the upper plate 7a lifted by the lift preventing portion 34 is sufficiently smaller than the pressing force applied to the upper plate 7a by the friction stir welding tool 31, and the thrust load is also a radial bearing. Therefore, a radial bearing is adopted as the bearing 35. Then, by adopting the radial bearing, the lifting prevention portion 34 can be made simple.

  Further, a gap 34b is formed on the lower surface 34a of the lifting prevention portion 34 using the lower portion of the space in which the bearing 35 is accommodated. The gap portion 34b is a space for allowing the burr 9 generated in the vicinity of the joint portion 7e during joining, and the plastic flow in the vicinity of the joint portion 7e is not hindered by ensuring a space in which the burr 9 can protrude. To play a role.

That is, in the friction stir welding tool 31 according to the third embodiment of the present invention, the lifting prevention portion 34 is disposed on the main body shaft portion 32 via the bearing 35.
By adopting such a configuration, it is possible to prevent the contact portion by the lifting prevention portion 34 of the upper plate 7a from being damaged.

In the friction stir welding tool 31 according to the third embodiment of the present invention, the bearing 35 is a radial bearing.
By adopting such a configuration, it is possible to prevent the contact portion by the lifting prevention portion 34 of the upper plate 7a from being damaged with a simple configuration.

Next, the joining state of the objects to be joined by the point joining method according to one embodiment of the present invention will be described with reference to FIGS. FIG. 5 is a schematic diagram showing a joining situation (before joining) according to the point joining method according to one embodiment of the present invention, and FIG. 6 shows a joining situation (part 1 during joining) by the point joining method according to one embodiment of the invention. FIG. 7 is a schematic diagram showing a joining situation (part 2 during joining) according to a point joining method according to an embodiment of the present invention, and FIG. It is a schematic diagram which shows (after joining).
In this embodiment, the point welding method in the case where the friction stir welding tool 11 according to the first embodiment is used will be described as an example. However, each friction stir welding tool 21 according to the second and third embodiments 21. Even when 31 is used, a similar point joining method can be applied.

As shown in FIG. 5, in this embodiment, the object 7 is composed of an upper plate 7a and a lower plate 7b, the thicknesses of the plates 7a and 7b are a and b, respectively, and the thickness of the object 7 is (a + b ), The situation where the upper plate 7a and the lower plate 7b are joined by the point joining method according to an embodiment of the present invention will be described as an example. In the present embodiment, the distance from the lower end surface 13a of the pin portion 13 to the lower surface portion 14a of the lifting prevention portion 14 is z.
In the present embodiment, the object 7 is composed of two layers, an upper plate 7a and a lower plate 7b. However, for example, even if the object is laminated in three or more layers, the object 7 of the present invention is used. The point joining method according to the embodiment can be applied, and the configuration of the workpiece to which the present invention is applied is not limited to the two-layer configuration.

  First, as shown in FIG. 6, the friction stir welding tool 11 is press-fitted from the state shown in FIG. 5 to a target predetermined depth where the distance between the lower end surface 13a of the pin portion 13 and the lower surface 7d of the lower plate 7b is c. To go. At this time, the distance from the upper surface 7c of the upper plate 7a to the lower surface portion 14a of the lifting prevention portion 14 (that is, the lifting allowance) is defined as d. At this time, the floating allowance d can be expressed by the following Equation 1.

That is, in the point joining method according to an embodiment of the present invention, when the friction stir welding tool 11 is rotated around the axis and pressed into the joint 7e of the article 7 from the upper plate 7a side, the lift prevention part 14 is pressed. Is in a state of being separated from the upper plate 14a.
By adopting such a configuration, the floating amount of the upper plate 7a can be regulated without reducing productivity.

  As shown in FIG. 7, when the friction stir welding tool 11 descends while rotating and the flow of the material is taken into account, the object to be joined 7 (that is, the upper plate) is generated by the frictional heat generated in the vicinity of the pin portion 13. 7 a and the lower plate 7 b) are softened, and a stirring action is generated by the screw formed on the pin portion 13, and plastic flow of the workpiece 7 softened around the pin portion 13 occurs. In the process of reaching the target predetermined depth c, the floating prevention unit 14 is not yet in contact with the upper plate 7a, and is maintained in a separated state. For this reason, the plastic flow in the vicinity of the joint 7e is not hindered, the plastic flow surely progresses, the structures of the upper plate 7a and the lower plate 7b are integrated and joined, and finally FIG. Transition to the state shown in.

Here, in the friction stir welding tool 11 according to the first embodiment of the present invention, the thickness of the upper plate 7a is a, the thickness of the lower plate 7b is b, the lower end surface 13a of the pin portion 13 and the lower surface 7d of the lower plate 7b, , C is the lifting allowance, z is the distance from the lower end surface 13a of the pin portion 13 to the lower surface portion 14a of the anti-lifting portion 14, and α is the maximum allowable lifting amount of the upper plate 7a. The value of z is determined so that the lifting allowance d satisfies the following mathematical formula 2 (that is, the arrangement (height) in the axial direction of the lifting prevention portion 14 is determined).
In other words, in the friction stir welding tool 11 according to one embodiment of the present invention, the amount of lifting of the upper plate 7a is determined by determining the value of z according to Equation 1 and Equation 2 below, and the upper plate 7a is allowed. The value of the lifting allowance d is equal to or less than the maximum value α of the lifting amount.

That is, the point joining method according to an embodiment of the present invention is a point joining method for an object to be joined 7 formed by laminating a plurality of plate-like materials including at least an upper plate 7a and a lower plate 7b. The main body shaft portion 12, the shoulder surface 12a formed at one end of the main body shaft portion 12, the pin portion 13 protruding from the shoulder surface 12a, and the outer peripheral surface of the main body shaft portion 12 radially outward. The friction stir welding tool 11 provided with the lifting prevention portion 14 projecting toward the joint is pressed into the joint 7e of the workpiece 7 from the upper plate 7a side while rotating around the axis of the friction stir welding tool 11, and joined. In the portion 7e, the upper plate 7a is lifted and brought into contact with the lifting prevention portion 14 in the vicinity of the bonding portion 7e while the workpiece 7 is bonded.
By adopting such a configuration, it is possible to regulate the lifting amount of the upper plate 7a with a simple configuration.

Further, in the friction stir welding tool 11 according to the first embodiment of the present invention, the lifting prevention portion 14 is determined from the distance (z-c) from the lower surface portion 14a to the lower end surface 13a of the pin portion 13 to be joined 7. The lower surface portion 14a when the distance obtained by subtracting the thickness (a + b) (that is, the lifting allowance d) is a positive value and the pin portion 13 is press-fitted to the workpiece 7 to a predetermined target depth. The distance from the upper plate 7a to the upper surface 7c (that is, the lifting allowance d) is arranged at a position where the distance is not more than the maximum allowable value α of the upper plate 7a.
By adopting such a configuration, the amount of lifting of the upper plate 7a can be regulated appropriately (that is, the lifting allowance d) without reducing productivity.

Then, when the friction stir welding tool 11 is raised after a predetermined holding time has elapsed, the state shifts to the state shown in FIG.
As shown in FIG. 8, in the point joining method according to one embodiment of the present invention, the amount of lifting of the upper plate 7a is limited by the lifting preventing portion 14, and this value d is free for the upper plate 7a. It is set to a smaller value than the amount of lift β when it is lifted.

  That is, in the point joining method according to an embodiment of the present invention, when the joining is started, the upper plate 7a and the lifting preventing portion 14 are not brought into contact with each other, and after the joining has progressed, the lifting of the upper plate 7a occurs. In addition, the upper plate 7a and the floating prevention portion 14 are brought into contact with each other so that the floating of the upper plate 7a is restricted. This prevents the progress of plastic flow at the joint 7e.

That is, in the point joining method according to an embodiment of the present invention, the amount of lifting of the upper plate 7a (that is, the amount of lifting d) is set to a value equal to or less than the maximum value α of the allowable amount of lifting of the upper plate 7a. I have to.
By adopting such a configuration, the amount of lifting of the upper plate 7a can be regulated appropriately (that is, the lifting allowance d) without reducing productivity.

Next, the joining result of the objects to be joined by the point joining method according to one embodiment of the present invention will be described with reference to FIG. FIG. 9 is a view showing a joining result obtained by the point joining method according to an embodiment of the present invention.
In addition, the joining result shown in FIG. 9 uses a material equivalent to A6022-T4 having a plate thickness of 0.9 mm (both upper and lower plates) as a test material, and spot-joined under the joining conditions of a pressure of 375 kgf and a rotational speed of 1800 rpm. The test results are shown. (1) Based on the result of joining by the point joining method of the prior art (without pressing), (2) The result of joining by the point joining method of the prior art (with pressing), (3) According to one embodiment of the present invention The result of joining by the point joining method is shown in comparison.

(Comparison of lifting amount)
As shown in FIG. 9 (a), in the case of (2) the prior art (with pressing), the amount of lifting can be made almost zero.
On the other hand, it can be seen that (3) in the point joining method according to one embodiment of the present invention, (1) the amount of lifting is reduced to about 1/10 compared to the prior art (without pressing). In addition, (3) In the point joining method according to one embodiment of the present invention, (2) the amount of lifting is larger than in the case of the conventional technique (with pressing), but in the present invention, there is a problem in quality. Since it is an idea to allow the upper plate to be lifted if it is not in the range, this difference in the amount of lift that naturally occurs is not a problem.

(Comparison of welding time)
As shown in FIG. 9B, in the case of (2) the prior art (with pressure), the time required for joining is about 3 times longer than that in (1) the prior art (without pressure). I understand that.
On the other hand, (3) In the point joining method according to an embodiment of the present invention, it can be seen that (1) the required joining time is approximately the same (about 1.1 times) as compared with the prior art (no pressing). . As described above, if almost the same productivity can be ensured as compared with the conventional technique (without pressing), the point joining method according to one embodiment of the present invention is introduced into the actual production line, and the conventional friction is achieved. It can be replaced with agitation spot welding.

(Comparison of tensile shear strength at joints)
As shown in FIG. 9C, in the case of (2) the prior art (with pressure), the tensile shear strength of the joint 7e is about 1.3 times that of (1) the prior art (without pressure). It turns out that it is strengthened to the extent.
On the other hand, (3) Even in the point joining method according to an embodiment of the present invention, the tensile shear strength of the joint 7e is strengthened by about 1.3 times compared with (1) the prior art (without pressing). I understand that. That is, according to the point joining method according to an embodiment of the present invention, even if the upper plate is allowed to lift in a range where there is no problem in quality, the tensile shear strength of the joint portion 7e is (2) conventional technology (pressing It can be seen that it can be strengthened as much as

  In other words, by adopting the point joining method according to one embodiment of the present invention, (1) while securing substantially the same productivity as in the case of the prior art (without pressing), (2) the prior art (with pressing). This makes it possible to reinforce the tensile shear strength of the joint 7e as in the case of.

The schematic diagram which shows the whole structure of a friction stir welding apparatus. The schematic diagram which shows the whole structure of the friction stir welding tool which concerns on the 1st Example of this invention. The schematic diagram which shows the whole structure of the friction stir welding tool which concerns on the 2nd Example of this invention. The schematic diagram which shows the whole structure of the friction stir welding tool which concerns on the 3rd Example of this invention. The schematic diagram which shows the joining condition (before joining) by the point joining method which concerns on one Example of this invention. The schematic diagram which shows the joining condition (part 1 during joining) by the point joining method which concerns on one Example of this invention. The schematic diagram which shows the joining condition (part 2 during joining) by the point joining method which concerns on one Example of this invention. The schematic diagram which shows the joining condition (after joining) by the point joining method which concerns on one Example of this invention. The figure which shows the joining result by the point joining method which concerns on one Example of this invention.

Explanation of symbols

7 Workpiece 7a Upper plate 7b Lower plate 11 Friction stir welding tool 12 Body shaft portion 12a Shoulder surface 13 Pin portion 14 Lifting prevention portion

Claims (9)

A cylindrical body shaft,
A shoulder surface formed at one end of the body shaft portion;
Protruding from the shoulder surface, a pin portion having a smaller diameter than the shoulder surface;
With
A friction stir welding tool used for spot joining of a workpiece formed by laminating a plurality of plate-like materials including at least an upper plate and a lower plate,
A lifting prevention portion projecting radially outward from the outer peripheral surface of the main body shaft portion;
A friction stir welding tool characterized by that. The lifting prevention part is
From the distance from the lower surface portion of the lifting prevention portion to the lower end surface of the pin portion,
The distance obtained by subtracting the thickness of the object to be joined is
A positive value, and
The pin portion is
When it is press-fitted to the target depth to the workpiece,
The distance from the lower surface to the upper surface of the upper plate is
Arranged at a position that is a distance equal to or less than the maximum allowable lifting amount of the upper plate,
The friction stir welding tool according to claim 1. In the lower surface portion,
A gap is formed between the outer peripheral surface of the main body shaft portion and the outer peripheral edge of the lifting prevention portion.
The friction stir welding tool according to claim 1 or 2, wherein the friction stir welding tool is provided. The lifting prevention part is
Removable with respect to the main body shaft,
The friction stir welding tool according to any one of claims 1 to 3, wherein the friction stir welding tool is provided. The lifting prevention part is
Disposed in the main body shaft through a bearing,
The friction stir welding tool according to any one of claims 1 to 4, wherein the friction stir welding tool is provided. The bearing is
Radial bearings
The friction stir welding tool according to claim 5. It is a point joining method of an object to be joined formed by laminating a plurality of plate-like materials including at least an upper plate and a lower plate,
A cylindrical body shaft,
A shoulder surface formed at one end of the body shaft portion;
Protruding from the shoulder surface, a pin portion having a smaller diameter than the shoulder surface;
A friction stir welding tool comprising a lifting prevention portion projecting radially outward from the outer peripheral surface of the main body shaft portion;
While rotating around the axis of the friction stir welding tool,
Press-fit from the upper plate side into the joint of the workpiece,
In the joint,
While joining the objects to be joined,
In the vicinity of the joint,
Raise the upper plate,
Abut against the lifting prevention part,
The point joining method characterized by the above-mentioned. The amount of lifting of the upper plate is
A value equal to or less than the maximum value of the allowable lift of the upper plate,
The point joining method according to claim 7 characterized by things. The friction stir welding tool,
When press-fitting into the joint portion of the workpiece from the upper plate side while rotating around the axis,
The lifting prevention part is
Spaced apart from the upper plate,
The point joining method according to claim 7 or 8, characterized in that.

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