JP2010214468A - Method and device for forming plate material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable a plate material made of alloy such as a magnesium alloy or metal to be formed at room temperature without using dies. <P>SOLUTION: A method for forming the plate material 1 made of alloy or metal into a three-dimensional shape includes pressing a tool 20 to the plate material 1 and moving the tool 20 relatively in the three-dimensional direction with respect to the plate material 1 while rotating it. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a plate material forming method and apparatus.

  Magnesium alloy has the lowest specific gravity among the metals used for structural members, is the lightest and at the same time has high strength, and is excellent in recyclability, electromagnetic shielding properties, aesthetics, etc. In view of the above, the adoption to mobile device casings and automobile members is expanding.

  However, unlike cubic metals such as aluminum and iron in the crystal structure, magnesium is a hexagonal metal, so it is difficult to perform plastic working at room temperature on a plate made of a magnesium alloy. It is processed by. However, such a process requires a mold for each of a variety of products produced in a variety of types and a large-scale apparatus for maintaining and controlling the material temperature at 200 to 300 ° C.

  In addition, aluminum alloys have been put into practical use in products in many fields, mainly automobiles, aircraft, railway vehicles, and ships, because of their high specific strength and high corrosion resistance.

  On the other hand, there is a problem that the market needs have shifted from small-quantity mass production to multi-variety small-quantity production, so that the cost of the product becomes too high in the conventional press molding. Therefore, it is necessary to develop a new thin plate processing method that can meet various needs of aluminum alloys.

  On the other hand, there is a sequential forming method (incremental forming) described in Patent Document 1 as a forming method for processing a metal plate at room temperature without requiring a mold. In this sequential forming method, a bar-shaped tool is pressed against a plate material, and the tool is moved relative to the plate material in a three-dimensional direction.

  Further, as a welding technique for magnesium alloy plates and aluminum alloy plates, there is a friction stir welding method (FSW: Friction Stir Welding). This is a method in which a tool is rotated while being inserted into a joined portion of a plate having a projection attached to a cylindrical tool tip, and the material softened by frictional heat generated at the tool shoulder is agitated and joined. .

JP2004-291066

  Since the sequential forming method described in Patent Document 1 is formed while the plate material is stretched little by little with a tool, the plate material can be formed into a complicated shape or a pointed shape that is difficult with conventional rolling or pressing.

  However, even with the conventional sequential forming method, there is still difficulty in room temperature processing of a plate material made of a difficult-to-process material such as a magnesium alloy.

  In the conventional sequential forming method, the tool comes into contact with the material through the forming oil, and the plate material is formed with the friction with the plate material being minimized.

  An object of the present invention is to make it possible to form a plate material made of an alloy such as a magnesium alloy, an aluminum alloy, a titanium alloy, or a metal at room temperature without using a mold.

  The invention according to claim 1 is a plate material forming method for forming a plate material made of an alloy or metal into a three-dimensional shape, and presses the tool against the plate material and moves the tool relative to the plate material in a three-dimensional direction while rotating the tool. It is what I did.

  The invention according to claim 2 is the invention according to claim 1, wherein the plate member is made of a magnesium alloy.

  The invention according to claim 3 is the invention according to claim 1, wherein the plate material is made of an aluminum alloy.

  The invention according to claim 4 is the invention according to claim 1, wherein the plate material is made of a titanium alloy.

  According to a fifth aspect of the present invention, in the invention according to any one of the first to fourth aspects, the plate material is formed by causing plastic flow due to frictional stirring caused by rotation of the tool to the plate material in contact with the tool. It is a thing.

  The invention according to claim 6 is the invention according to claim 5, in which the tool is in contact with the plate material without using molding oil.

  The invention according to claim 7 is the invention according to claim 5 or 6, further comprising a support for supporting the plate material on the back side of the plate material in contact with the tool.

  The invention according to claim 8 is the invention according to claim 7, wherein the receiving member is formed of a molded model of a plate material.

  The invention according to a ninth aspect is the invention according to any one of the first to eighth aspects, wherein the tool is pressed against a plate material and relatively moved over a circumference along a three-dimensional contour line to be formed of the plate material. This is repeated at various points in the height direction of the plate material.

  The invention according to claim 10 is a plate material forming apparatus for forming a plate material made of an alloy or metal into a three-dimensional shape, a plate material support device for supporting an outer edge portion of the plate material, a tool in contact with the plate material, and a tool rotation for rotating the tool. The apparatus includes a moving device that relatively moves the tool and the plate material in a three-dimensional direction.

  The invention according to claim 11 is the invention according to claim 10, wherein the plate material is made of a magnesium alloy.

  The invention according to claim 12 is the invention according to claim 10, wherein the plate material is made of an aluminum alloy.

  The invention according to claim 13 is the invention according to claim 10, wherein the plate material is made of a titanium alloy.

  The invention according to claim 14 is the invention according to any one of claims 10 to 13, wherein the moving device further includes a plate material moving device for moving the plate material in the orthogonal biaxial direction, and a tool in each of the orthogonal biaxial directions. And a tool moving device that moves in a direction orthogonal to each other.

  According to a fifteenth aspect of the invention, in the invention according to any one of the tenth to fourteenth aspects of the invention, there is further provided a receiving member that is disposed on the back side of the plate material that is in contact with the tool and supports the plate material.

  The invention according to claim 16 is the invention according to claim 15, wherein the receiver is made of a molded model of a plate material.

(Claims 1-4, 10-14)
(a) The formability of the plate material can be improved by pressing the tool against the plate material and moving the tool relative to the plate material in a three-dimensional direction while rotating the tool. Accordingly, a plate material made of an alloy such as a magnesium alloy, an aluminum alloy, a titanium alloy, or a metal can be formed at room temperature without using a mold (applicable to low-cost, high-mix low-volume production) and without heating.

(Claim 5)
(b) Forming the plate material by causing plastic flow due to friction stirring caused by rotation of the tool on the plate material in contact with the tool. By stirring and flowing the plate material in a solid phase, the forming limit depth of the plate material can be increased, and the moldability can be reliably improved. At the same time, the metal structure is refined at the processed portion of the formed plate material, and various mechanical properties are improved. For example, the crystal grains after processing the plate material become smaller, and as a result, dislocations do not move easily and become high strength, the crystal grains are easy to rotate, the ductility is improved, and the spring back after processing is reduced. .

(Claim 6)
(c) By making the tool come into contact with the plate material without using the molding oil, the plastic flow due to the frictional stirring described in (b) due to the rotation of the tool can be remarkably caused.

(Claims 7 and 15)
(d) When the supporter that supports the plate material is disposed on the back side of the plate material that comes into contact with the tool, the plastic flow due to the frictional stirring described in (b) due to the rotation of the tool can be remarkably caused.

(Claims 8 and 16)
(e) By using the receiving tool as a forming model of the plate material, the forming model can be used as the receiving tool of the above (d).

(Claim 9)
(f) The tool is pressed against the plate material and relatively moved over one circumference along the contour line of the solid shape to be formed of the plate material, and is repeated at various points in the height direction of the plate material. Accordingly, the plate material is formed while being gradually extended with a tool, and the plate material can be formed into a complicated shape or a pointed shape.

FIG. 1 is a cutaway perspective view showing an example of a molding apparatus. FIG. 2 is a perspective view showing another example of the molding apparatus in a cutaway manner. FIG. 3A is a schematic diagram showing an experimental apparatus in an experimental example of the present invention. FIG. 3B is a schematic diagram showing a forming pattern of a plate material in an experimental example of the present invention. FIG. 4 is a graph showing the tool rotation speed and the forming limit depth of the plate material. FIG. 5 is a photomicrograph showing the structure on the tool pushing side of the plate material. FIG. 6 is a photomicrograph showing the structure of the back side of the tool pressing of the plate material. FIG. 7 is an explanatory view showing the spring back after the plate material is formed. FIG. 8A is a graph showing the relationship between the tool moving speed and the half apex angle at which the plate material can be formed. FIG. 8B is a schematic diagram showing an angle formed by the central axis of the tool with respect to the forming surface of the plate material. FIG. 9 is an explanatory view showing the processing state and structure of the plate material. FIG. 10 is a graph showing changes in the processing state of the plate material depending on the tool moving speed and the half apex angle of the plate material. FIG. 11 is a graph showing a change in the structure of the tool pressing side of the plate material depending on the tool moving speed and the half apex angle of the plate material. FIG. 12 is a graph showing changes in the structure of the back side of the tool pressing of the plate material according to the tool moving speed and the half apex angle of the plate material. FIG. 13A is a chart showing molding conditions in a molding example in which the receiving device of the present invention is applied. FIG. 13B is an explanatory view showing a molding result in a molding example in which the receiving device of the present invention is applied. FIG. 14A is a chart showing molding conditions in the molding example of the concave space molding of the present invention. FIG. 14B is an explanatory view showing a molding result in the molding example of the concave space molding of the present invention. FIG. 15 is a graph showing the relationship between the tool moving speed and the half apex angle at which the plate material can be formed. FIG. 16 is a graph showing the relationship between the tool moving speed and the half apex angle at which the plate material can be formed. FIG. 17 is a graph showing the relationship between the tool rotation speed and the half apex angle at which the plate material can be formed. 18A and 18B are graphs showing the processing temperature during molding. FIG. 19 is a graph showing the relationship between the processing temperature and the moldable half apex angle. 20 (A) to 20 (D) are explanatory views showing the processing state of the plate material. FIGS. 21A to 21C are explanatory views showing the processing state of the plate material. FIG. 22 is a graph showing the theoretical relationship between the half apex angle and the equivalent strain and elongation. FIG. 23 is a graph showing the hardness of the processed part. FIG. 24 is a graph showing the tensile strength of the processed part. FIG. 25 is a graph showing the relationship between the tool movement speed and the tool rotation speed. FIG. 26 is a graph showing the tool rotation speed and the forming limit depth of the plate material. FIGS. 27A and 27B are explanatory views showing the processed state of the plate material. FIGS. 28A and 28B are graphs showing processing temperatures during molding. FIG. 29 is a graph showing the relationship between the tool rotation speed and the half apex angle. FIG. 30 is a graph showing the theoretical relationship between the half apex angle and the equivalent strain and elongation. FIGS. 31A and 31B are explanatory views showing the processing state of the plate material. FIGS. 32A and 32B are explanatory views showing the processing state of the plate material. FIG. 33 is a graph showing the relationship between the tool moving speed and the half apex angle. FIG. 34 is a photomicrograph showing the structure of the plate material. FIG. 35 is a graph showing the processing temperature during molding. FIG. 36 is a graph showing the hardness of the processed part. FIG. 37 is a graph showing the tensile strength of the processed part.

  A friction stir incremental forming apparatus 100 shown in FIG. 1 forms a plate 1 made of an alloy such as a magnesium alloy, an aluminum alloy, a titanium alloy or a metal into a three-dimensional shape, and supports the outer edge of the plate 1. It has the apparatus 10, the tool 20 which touches the board | plate material 1, the tool rotation apparatus 30 which rotates the tool 20, and the moving apparatus 40 which moves the tool 20 and the board | plate material 1 relatively in a three-dimensional direction. The plate material supporting device 10, the tool 20, the tool rotating device 30, and the moving device 40 of the present embodiment are configured as follows.

  The plate material support device 10 is a square frame-shaped material presser plate that supports the outer edge portion of the plate material 1 with the square frame-shaped support plate 12 attached to the upper surface of the table 11 being sandwiched between the upper surface of the support plate 12. 13

  The tool 20 has a rod shape arranged vertically with respect to the upper surface of the table 11. For example, the tip R surface is pressed against the surface of the plate 1 in the frame of the material pressing plate 13.

  The tool rotating device 30 rotates the tool 20 around the central axis at a high speed of, for example, 2000 rpm or more, preferably 7000 rpm or more.

  The moving device 40 includes a plate material moving device 41 that controls the position of the table 11 so as to move the plate material 1 in the orthogonal biaxial directions (X-axis and Y-axis directions), and the tool 20 orthogonal to each of the orthogonal biaxial directions. And a tool moving device 42 that moves in the direction (Z-axis direction).

  The friction stir incremental forming apparatus 100 is disposed on the back side of the plate 1 with which the tool 20 is in contact, and has a support 50 that supports the plate 1 at the same position as the X-axis and Y-axis direction positions of the tool 20. The receiving tool 50 of the present embodiment is supported by the table 11 and includes a forming model 51 that has formed all or a main part of the forming shape of the plate 1.

  The friction stir incremental forming apparatus 100 presses the tool 20 against the plate material 1 and moves the tool 20 relative to the plate material 1 in a three-dimensional direction following the forming model 51 while rotating the tool 20, thereby forming the plate material 1 into the forming model. It is formed into a three-dimensional shape following 51.

  At this time, the friction stir incremental forming apparatus 100 presses (or pushes) the tool 20 against the plate material 1 and rotates the tool 20 while rotating the tool 20 relative to one another along the contour line of the solid shape to be formed. Is moved at various points in the height direction of the plate 1. That is, based on the three-dimensional shape data to be formed of the plate material 1, the table 20 and the plate material 1 are moved in the X-axis and Y-axis directions by the plate material moving device 41 while pressing the tool 20 against the plate material 1 and rotating the tool 20. Then, after one cycle of machining is performed in which the tool 20 is moved along a contour line following the determined locus, the tool 20 is moved by a fixed feed pitch in the Z-axis direction, and the tool 20 is moved to the next contour line. Positioning on top and performing the next cycle of machining is repeated from the upper edge to the lower edge of the plate 1.

  The friction stir incremental forming apparatus 100 uses a table 11 as shown in FIG. 2 instead of the forming model 51 when the three-dimensional shape to be formed of the plate 1 is a symmetrical three-dimensional shape around the central axis of the plate 1. The top plate jig 60 supported by the can be used. The top plate jig 60 has a flat surface, a convex surface, or a concave surface that matches the top contour on the central axis of the three-dimensional shape to be molded of the plate material 1 and is disposed on the back side of the plate material 1 with which the tool 20 is in contact, and on the central axis of the plate material 1 The plate 1 is supported by The friction stir incremental forming apparatus 100 presses the tool 20 against the plate 1 around the central axis of the plate 1 and moves the tool 20 relative to the plate 1 in a three-dimensional direction while rotating the tool 20. Is formed into a three-dimensional shape symmetric about the central axis. Also in this case, like the friction stir incremental forming apparatus 100 of FIG. 1, the friction stir incremental forming apparatus 100 presses (or pushes) the tool 20 against the plate 1 and rotates the tool 20 while rotating the tool 20. The relative movement over one circumference along the contour line of the three-dimensional shape to be molded is repeated at various points in the height direction of the plate 1.

  In the friction stir incremental forming apparatus 100, the three-dimensional shape of the plate 1 to be formed is a symmetrical three-dimensional shape around the central axis of the plate 1, and the tool 20 is within the frame of the material pressing plate 13. When the plate material 1 is formed in a concave shape in the vertically lower side, it is possible to form a concave space in which neither the forming model 51 nor the top plate jig 60 is provided on the back surface side of the plate material 1 (for example, FIG. 14 (A), FIG. 14 ( B)).

  However, in the friction stir incremental forming apparatus 100, the plate 1 is made of an alloy or metal such as magnesium alloy, aluminum alloy, titanium alloy, etc., and the tool 1 is rotated by the tool rotating device 30 on the plate 1 in contact with the tool 20. The plate material 1 is formed by causing plastic flow based on friction stirring resulting from the above-described high-speed rotation of 20.

  When the tool 20 is in contact with the plate 1 without rotating through the molding oil (lubricating oil) and rotates as described above, the friction stirrer caused by the rotation of the tool 20 can be surely caused in the plate 1.

  Therefore, according to the friction stir incremental forming apparatus 100, the following effects can be obtained. The effects described below are supported by the experimental results described later.

  (a) The formability of the plate 1 can be improved by pressing the tool 20 against the plate 1 and moving the tool 20 relative to the plate 1 in a three-dimensional direction while rotating the tool 20. Thus, the plate material 1 made of an alloy such as a magnesium alloy, an aluminum alloy, a titanium alloy, or a metal can be formed at room temperature without using a mold (corresponding to low-cost, high-mix low-volume production) and without heating.

  (b) The plate material 1 is formed by causing plastic flow due to frictional stirring caused by the rotation of the tool 20 to the plate material 1 in contact with the tool 20. By stirring and flowing the plate material 1 in a solid phase, the forming limit depth of the plate material 1 can be increased, and the moldability can be reliably improved. At the same time, the metal structure is refined at the processed portion of the molded plate 1 and various mechanical properties are improved. For example, the crystal grains after processing of the plate 1 are reduced, and as a result, dislocations are difficult to move and the strength is increased, the crystal grains are easy to rotate, the ductility is improved, and the spring back after processing is reduced. Become.

  (c) By making the tool 20 contact the plate member 1 without using molding oil, the plastic flow due to the frictional stirring described in (b) due to the rotation of the tool 20 can be remarkably caused.

  (d) When the receiving member 50 that supports the plate material 1 is disposed on the back side of the plate material 1 with which the tool 20 is in contact, the plastic flow due to the frictional stirring described in (b) above due to the rotation of the tool 20 can be remarkably caused. .

  (e) By using the receiving tool 50 as the forming model 51 of the plate 1, the forming model 51 can be used as the receiving tool 50 of the above (d).

  (f) The tool 20 is pressed against the plate material 1 and relatively moved over one circumference along the contour line of the three-dimensional shape to be formed of the plate material 1 at various points in the height direction of the plate material 1. Accordingly, the plate material 1 is formed while being gradually extended by the tool 20, and the plate material 1 can be formed into a complicated shape or a pointed shape.

  Hereinafter, experimental results of the present invention will be described. In this experiment, for each of (I) magnesium alloy and (II) aluminum alloy, as shown in FIGS. 3 (A) and 3 (B), the outer edge portion of the plate material 1 as the test material is fixed to the support plate 12 and the material presser. The tool 13 is supported by pressing with the plate 13, the tip R surface of the rod-shaped tool 20 is pressed against the plate material 1, and the tool 20 is rotated at a high speed (tool rotation speed ω), while the tool 20 is contoured according to the locus K of the desired forming pattern. One cycle of machining (moving tool speed v) in the X axis and Y axis directions is performed over the entire circumference, and after this one cycle of machining, the tool 20 is moved by a constant feed pitch p in the Z axis direction. The tool 20 is positioned on the next contour line, and the next one cycle of processing is repeated. The molded shape and optical micrograph of the processed plate material 1 are collected, and the moldability is investigated.

  In this experiment, an NC machine tool was used, and the tool 20 attached and fixed to the NC machine tool was used. The tool 20 was made of SKH51 (high speed tool steel) and had a hemispherical surface with a diameter of 6 mm, a length of 70 mm, and a tip R3 mm. By making the tip of the tool 20 a hemispherical surface, the thin plate 1 can be formed into various shapes. The rotation and movement of the tool 20 were controlled by an NC code input to a computer connected to the NC machine tool.

  In this experiment, a 100 mm square flat plate 1 was formed in the shape of a square regular square pyramid with a bottom of 80 mm on one side. Forming was investigated by changing the tool rotation speed ω [rpm] and the tool moving speed v [mm / min] and obtaining the minimum half apex angle θ that can be formed. The tool 20 was moved according to the NC code input by the computer. First, molding was started from the bottom surface of the regular quadrangular pyramid, and the tool 20 was pushed 0.5 mm, and then turned once counterclockwise. The tool was pushed 0.5 mm in the Z direction during one revolution of the tool and moved inward by an arbitrary length according to the set half apex angle. For example, in the case of molding with a half apex angle of 45 degrees, it was moved inward by the same length as 0.5 mm, which is the pushing length in the Z direction. Thereafter, the tool moved along the inner path (2) that was slightly smaller than the path (1), and this was repeated until the height of the regular quadrangular pyramid reached 20 mm. When cracks occurred in the sample during molding, the molding was interrupted, and the indentation length in the path immediately before fracture was defined as the molding limit height (the limit height at which molding can be performed without fracture).

[I] Magnesium alloy For the test material, 0.5 and 0.7 mm thick AZ31 annealed material, 0.5 mm thick AZ61 annealed material, and 0.8 mm thick AZ80 extruded material are used as test materials. A 100 mm square plate was used. Table 1 shows the chemical composition of the test material, and Table 2 shows the physical properties of the test material.

(A) Relationship between tool rotation speed ω and forming limit height of plate 1 (Fig. 4)
FIG. 4 shows the relationship between the tool rotational speed ω and the forming limit height of the plate 1 when the tool moving speed v = 3000 mm / min and the half apex angle θ = 45 degrees for AZ31 having a thickness t = 0.5 mm. Is.

  According to FIG. 4, when the tool rotation speed ω of the tool 20 is set to 7000 rpm or more, the forming limit height of the plate material 1 can be drastically improved, and when the tool rotation speed ω is set to 8000 rpm or more, the forming limit height of the plate material 1 is greatly improved. It is recognized that it can be done.

  As shown in FIG. 4, in forming a magnesium alloy plate at room temperature, the forming method is improved by using the forming method of the present invention rather than the conventional incremental forming (ω = 0 rpm), and the forming limit height increases as the tool is rotated. Improved. This is probably because the material was softened by frictional heat by rotating the tool to some extent during molding, and the molding limit height was improved. However, since the tool rotation speed and the amount of heat input are in a proportional relationship, it seemed that the tool rotation speed and the forming limit height were simply proportional, but if the tool rotation speed was less than 8000 rpm, the tool rotation speed could be increased. The forming limit height does not change much, and the forming limit height is rapidly improved when the tool rotation speed is 8000 rpm or more, and the forming limit height of the experimental apparatus is reached. From this, it seems that there is a threshold in the tool rotation speed for plastic flow due to friction stirring, and it is not simply due to frictional heat with the tool, but formability is improved by causing plastic flow by stirring. It is thought that.

(B) Changes in the structure of the plate 1 (FIGS. 5 and 6)
5 and 6, for AZ31 having a plate thickness t = 0.5 mm, the tool moving speed v = 3000 mm / min, the half apex angle θ = 45 degrees, and the tool rotation speed ω of the tool 20 is 0 rpm, 7000 rpm, and 8000 rpm. FIG. 5 shows a structure on the tool pressing side of the plate 1 processed by the tool 20 (FIG. 5) and a structure on the back side of the tool pressing of the plate 1 (FIG. 6).

  According to FIGS. 5 and 6, it is recognized that the crystal grains of the plate material 1 become finer as the tool rotation speed ω is increased by processing, and that the tool push side of the plate material 1 becomes finer. The size of the crystal grains of the plate 1 before processing was about 10 μm or less at the time of rolling in the surface layer, and about 10 μm in other than the surface layer. The size of the crystal grains of the plate material 1 after processing is so fine that it is difficult to confirm in the surface layer, and it is 1 μm or less from the surface layer to 100 μm, and it is recognized that these fine crystal grains are generated by friction stirring. Further, since fine crystal grains are mixed even from the surface layer of the plate material 1 below 100 μm, it is considered that the structure subjected to frictional stirring is mixed to the back side of the plate material 1.

(C) Spring back after forming plate 1 (Fig. 7)
FIG. 7 shows a case where the tool movement speed v = 3000 mm / min, the half apex angle θ = 45 degrees, and the tool rotation speed ω of the tool 20 is 0 rpm, 7000 rpm, and 8000 rpm for AZ31 having a thickness t = 0.5 mm. 20 shows a state of the spring back after the plate material 1 processed by 20 is formed.

  According to FIG. 7, it is recognized that the spring back after the plate 1 is formed can be suppressed by increasing the tool rotation speed ω of the tool 20 and frictionally stirring the plate 1.

(D) Relationship between the tool moving speed v and the half apex angle θ in which the plate 1 can be formed (FIGS. 8 to 12, FIG. 15 and FIG. 16)
FIG. 8A shows the tool moving speed v of the tool 20 and the half apex angle θ (see FIG. 8) when the tool rotational speed ω of the tool 20 is 10,000 rpm for AZ31 having a plate thickness t = 0.5 mm. 8 (B)) is shown.

  According to FIG. 8A, it is possible to form a smaller half apex angle as the tool moving speed is reduced, and the minimum half apex angle θmin that can be formed at the moving speed v = 1000 to 2000 mm / min. = 25 degrees. It can be seen that if θ ≧ 55 degrees, molding can be performed under all conditions. In a range where θ is small, forming is possible by slowing down the tool moving speed v. It will be appreciated that it is necessary to select an appropriate tool moving speed v at each half apex angle θ.

  FIG. 9 shows a state of forming the plate 1 for AZ31 having a thickness t = 0.5 mm when the tool rotation speed ω of the tool 20 is 10,000 rpm, the tool moving speed v of the tool 20 is 1500 mm / min, and θ is 25 degrees. The material was not seized on the tool 20 and the state of the processed surface was good. Further, it is recognized that the crystal grains are refined on both the tool pressing side and the tool pressing back side of the plate 1.

  FIG. 10 shows the shape of the processed plate 1 in the forming condition range of the tool moving speed v and the half apex angle θ corresponding to FIG.

  FIGS. 11 and 12 show the tool pressing side structure of the processed plate 1 (FIG. 11) and the tool of the plate 1 in the molding condition range of the tool moving speed v and the half apex angle θ corresponding to FIG. The structure | tissue (FIG. 12) of an indentation back side is shown. It is recognized that the crystal grains of the plate 1 are refined under conditions where molding is possible.

  In FIGS. 10 to 12, when attention is paid to the tool moving speed v, the sample molded at v = 500 mm / min was too slow to move, so that it could not be formed well due to excessive stirring. Looking at the structure photograph, it can be seen that the surface on the tool indentation side is very rough, and the structure on both the tool indentation side and the tool indentation back side is fine compared to the sample with a moving speed of v = 3000 mm / min. It was not converted. In addition, looking at the tool after molding, characteristic tool seizure due to excessive stirring was observed. For this reason, it seems that the board | plate material 1 was also not able to be shape | molded accurately. On the other hand, the plate 1 molded at the moving speed v = 6000 mm / min was broken in the middle due to insufficient stirring because the moving speed was too fast. The refinement of crystal grains was also confirmed only in a very small region on the tool pushing side, which also indicates that stirring is insufficient.

  Next, when paying attention to the half apex angle, the plate material 1 molded with the half apex angle θ = 60 degrees could be formed up to the forming limit height of the experimental apparatus. However, since the half apex angle is large, the interval through which the tool passes is relatively wide, resulting in rough forming. For this reason, when forming with a large half apex angle, the pressing amount of the tool 20 must be finely cut accordingly. Although the structure of the processed part was not as fast as the moving speed v = 3000 mm / min, the structure was refined except for a part on the back side of the tool press. Further, when looking at the plate 1 formed with a half apex angle θ = 30 degrees, seizure of the tool 20 was observed. However, looking at the structure of the processed part, it can be seen that the crystal grains are finer and sufficiently stirred. From this, in order to prevent seizure of the tool 20, it is considered necessary to perform exchange and cleanup of the tool during molding, adjustment of the tool pressing amount, and the like. In particular, when forming by changing the half apex angle θ, the selection of the tool push-in amount seems to be important.

Similarly, FIG. 15 and FIG. 16 show the results of examining the range of the half apex angle θ that can be formed for AZ61 (plate thickness t = 0.5 mm) and AZ80 (plate thickness t = 0.8 mm) plates. The minimum half apex angle that can be molded was AZ61, and the minimum half apex angle θ _{min was} 30 degrees, and AZ80 was the minimum half apex angle θ _min = 40 degrees.

(E) Relationship between the tool rotation speed ω and the half apex angle θ of the plate 1 that can be formed (FIG. 17)
Fig. 17 shows the result of investigating the range of the half apex angle θ that can be formed by using a AZ31 plate with a thickness t = 0.5 mm, fixing the tool movement speed to v = 1500 mm / min, and changing the tool rotation speed. Show. As the tool rotation speed was increased, a smaller half apex angle could be formed, and at the tool rotation speed ω = 10000 rpm, formation was possible up to the minimum half apex angle θ _min = 25 degrees. For this reason, more heat input is required to form a smaller half apex angle, and as the heat input increases, the temperature of the material increases and the flow stress of the material decreases, causing plastic flow. It is thought that it becomes easy.

(F) Processing temperature during molding (Figure 18)
FIG. 18 shows the temperature change of the processed part when an AZ31 plate (plate thickness t = 0.5 mm) is formed. FIGS. 18 (A) and 18 (B) are both formed when the tool rotational speed ω = 10000 rpm. 18A shows a tool moving speed v = 3000 mm / min and a half apex angle θ = 45 degrees, and FIG. 18B shows a tool moving speed v = 1500 mm / min and a half apex angle θ = 30 degrees. It shows the temperature change when molding with. Under both conditions, the maximum reached 215 ° C and 343 ° C, and increased to above the recrystallization temperature. Furthermore, the processed part is greatly strained by stirring, and dynamic recrystallization seems to have occurred.

(G) Comparison with warm and hot forming (Figs. 19 and 20)
FIG. 19 shows the relationship between the processing temperature and the moldable half apex angle when incremental forming is performed warm and hot using an AZ31 plate (plate thickness t = 0.5 mm). In order to compare the warm and hot incremental forming with the molding method of the present invention, the tool moving speed v = 1500 mm / min which is the molding condition when the minimum half apex angle θ _min = 25 degrees can be formed. Incremental forming was performed at a tool rotation speed ω = 0 rpm. As can be seen from FIG. 18, at the recrystallization temperature of 180 ° C. or higher, which is the recrystallization temperature of the AZ31 alloy plate, molding was possible up to the minimum half vertex angle θ _min = 35 degrees. From this, it was found that the molding method of the present invention is a very effective method that does not require preheating of the plate, blank holder, or die to be molded. In addition, in the warm and hot incremental forming, the moldability is rapidly improved by heating to a temperature higher than the recrystallization temperature, which indicates that the moldability of magnesium is good at high temperatures. It has already been reported that the formability of AZ31 is improved at high temperatures even in deep drawing and stretch forming.

FIG. 19 shows a photograph of the appearance of a sample molded by incremental forming between warm and hot. Moreover, the external appearance photograph of the sample shape | molded by this invention shaping | molding method is also shown as a comparison. Looking at FIGS. 20B and 20C formed at a processing temperature T = 180 degrees, FIG. 20B formed at a half apex angle θ = 45 degrees is successfully formed. 20C formed with a half apex angle θ _min = 35 degrees in comparison with FIG. 20A formed with the minimum half apex angle θ = 25 degrees that can be formed by the forming method of the present invention. In addition, many rough skins were observed in the processed parts. In particular, in the final stage of molding, since the processing was performed while making a loud sound, rough skin at this stage is remarkable. Although a half apex angle θ _min = 35 degrees was obtained, it can be said that the molding was severe. Finally, looking at FIG. 20D, which was molded at a processing temperature T = 250 ° C. and a half apex angle θ = 30 degrees, it broke during the molding. In the case of molding at the processing temperature T = 180 ° C. with the same half apex angle, breakage occurred in the middle of the molding.

(H) Elongation / equivalent strain of machined part (Figs. 21 and 22)
Fig. 21 shows the appearance of a sample formed from AZ31 plate (thickness t = 0.5mm), AZ61 plate (thickness t = 0.5mm) and AZ80 plate (thickness t = 0.8mm) to the smallest half apex angle that can be formed. Show photos. The molding conditions of the sample shown in the photo are AZ31 for tool rotation speed ω = 10000 rpm, moving speed v = 1500 mm / min, minimum half apex angle θ = 25 degrees, AZ61 for tool rotation speed ω = 10000 rpm, moving speed v = 3000 mm The minimum half apex angle θ = 30 degrees at / min, AZ80 could be molded to the minimum half apex angle θ = 35 degrees at a tool rotation speed ω = 10000 rpm, moving speed v = 4500 mm / min. From the appearance photograph, it can be seen that in AZ61 and AZ80, the surface roughness of the processed part is remarkable, but the sample can be molded without distortion.

  FIG. 22 shows the theoretical relationship between the half apex angle, the equivalent strain, and the elongation. FIG. 22 shows how much strain is applied to the processed part and how much stretched by this forming method. For example, when forming with a half apex angle θ = 30 degrees, the length of the conical surface after forming is doubled before forming by the trigonometric function, so that the elongation of the processed portion becomes 100%. As the half apex angle θ becomes smaller, the conical surface has a steeper angle. Therefore, as shown in FIG. 22, the elongation of the processed portion also increases, and the applied equivalent strain also increases.

Table 3 shows the elongation values when the samples were molded with a half apex angle θ = 45 degrees and the minimum moldable half apex angle θ _min . The elongation at room temperature according to the tensile test of AZ31 was 26%, but the elongation of the processed part when molded at a half apex angle of 25 degrees was 137%, confirming a marked improvement in elongation. Similarly, for AZ61 and AZ80, the elongation at room temperature was 17% and 24%, respectively, and the elongation of the processed part reached 100% and 56% by this molding method, respectively.

  By the way, the processed part during molding by the molding method of the present invention has reached 300 ° C. or higher. Therefore, comparing the elongation in the high temperature range, it has been reported that the elongation of the AZ31-O wrought material used in this experiment extends to over 80% at 300 ° C. Since the forming method of the present invention can be formed up to 137% (AZ31-0.5 mm) of the processed part without preheating the sample, it can be seen that the forming method of the magnesium alloy plate is greatly improved. Magnesium is considered to be active in non-bottom slip at high temperatures, and at the same time, grain boundary slip contributes to plastic deformation. From this, it is considered that not only the high temperature but also the grain size is refined by the molding method of the present invention, and more grain boundary sliding is activated, leading to a significant improvement in moldability.

Table 4 shows the value of the equivalent strain when each sample was molded with a half apex angle θ = 45 degrees and a minimum moldable half apex angle θ _min . Further, the equivalent strain obtained from the tensile test of each sample was also shown, and the amount of strain applied during the molding and the tensile test was calculated. Note that the equivalent strain applied to the machined part at the time of forming is equivalent to the case where it is assumed that the thickness of the machined part is simply reduced and extended in a uniaxial direction, ignoring the distortion in the tool rotation direction. As a result, it was found that the strain applied at the time of molding in all the samples was larger than the breaking strain when the green material was pulled. In other words, the strain to the extent of breaking was already given before the tensile test of the processed part, and then the strain was further given a strain of 0.1 to 0.2 mm by the tensile test, leading to the breaking. In particular, the amount of strain of a sample that was formed by molding a AZ31 plate with a half apex angle of 25 degrees and performing a tensile test is 1 mm or more. This also shows that the moldability is greatly improved by the developed molding method.

(I) Changes in the hardness and structure of the processed part Formed using AZ31 plate with thickness t = 0.5mm, 0.7mm, AZ61 plate with thickness t = 0.5mm, and AZ80 plate with thickness t = 0.8mm A cross section hardness test was performed. All the molding conditions of the sample molded with a half apex angle θ = 45 degrees are unified to the tool rotation speed ω = 10000 rpm and the tool movement speed v = 3000 mm / min. Only the sample molded with the half apex angle θ = 25 degrees is the tool rotation speed. ω = 10000 rpm and tool moving speed v = 1500 mm / min. The Vickers hardness of each sample is shown in FIG.

(1) AZ31 plate (thickness t = 0.5mm)
The hardness of the raw material was 70.8HV0.1, and when molded with a half apex angle θ = 45 degrees, the hardness was 77.9HV0.1, an increase of about 10% compared to before molding. Looking at the structure of the processed part at this time, both the front side and the back side were made finer than before molding. However, when it was molded with a half apex angle θ = 25 degrees, it decreased to 65.6HV0.1. At this time, the structure of the processed part was not refined as in the case of forming at a half apex angle θ = 45 degrees compared to before forming. Moreover, since the hardness has decreased compared to before molding, the amount of heat input is probably larger than when molded with a half apex angle θ = 45 degrees, and the hardness decreased because the crystal grains became coarse after recrystallization. I think that the. In addition, since the processed part is more stirred as compared with the case of molding at a half apex angle θ = 45 degrees, it is considered that the hardness has decreased due to formation of a texture by stirring. The formation of texture by agitation has also been reported in the joints of FSW, and it seems that the hardness decreased because the formation of the texture occurred significantly compared to the case of forming with a half apex angle θ = 45 degrees. It is.

(2) AZ31 plate (thickness t = 0.7mm)
The hardness of the raw material was 73.7HV0.1, but when the half apex angle was formed at θ = 45 degrees, the hardness was 77.6HV0.1 and the thickness t = 0.5mm compared to before molding. Improved. Looking at the structure of the processed part, the structure after molding was refined on the front side of the tool press, but was not refined up to the back side as the plate thickness t = 0.5 mm. However, since the structure has become finer than before molding, it is considered that the hardness has increased as a result.

(3) AZ61 plate (thickness t = 0.5mm)
The hardness of the raw material was 93.2HV0.1, but when the half apex angle was formed at θ = 45 degrees, the hardness decreased to 80.7HV0.1. In the processed part structure, precipitates were confirmed on the tool indentation side and the tool indentation back side by machining. However, it is reported that Mg ₁₇ Al _{12 that} is precipitated by AZ61 does not affect the hardness, and as described above, it is thought that this is due to the formation of texture by stirring.

(4) AZ80 board (thickness t = 0.8mm)
Hardness of the raw material was the 84.5HV0.1, hardness the half apex angle is formed at theta = 45 ^o has to 96.6HV0.1 as seen in two samples hardness of AZ31 rise did. The microstructure of the machined part was confirmed to be refined on both the tool indentation side and the tool indentation back side, and was very remarkable on the tool indentation side. From this, it seems that the refinement of crystal grains led to an increase in hardness. Incidentally, AZ80 used in this experiment was an extruded material, but there was no difference in structure in the direction of extrusion and no difference in hardness.

(J) Tensile strength of the processed part and change in structure (Fig. 24)
A test piece was cut out from the conical surface of the molded sample, and a tensile test of the processed part was performed. The sample used for the test was the same sample as in the hardness test. FIG. 24 shows the tensile strength of each sample. Table 5 also shows the thickness of the sample of the processed part.

(1) AZ31 plate (thickness t = 0.5mm)
The tensile strength of the raw material was 260 MPa, and when it was molded at a half apex angle θ = 45 degrees, the tensile strength was 289 MPa, an increase of about 10% compared to before molding. Looking at the structure of the processed part at this time, both the front side and the back side were made finer than before molding. However, when it was molded at a half apex angle of θ = 25 degrees, it decreased to 216 MPa. At this time, the structure of the processed part was not refined as in the case of forming at a half apex angle θ = 45 degrees compared to before forming. Moreover, since the strength is lower than that before molding, it is considered that the strength is probably reduced by the formation of texture on the surface of the test piece by processing and the formation of texture by stirring. As can be seen from Table 5, the unevenness of the test piece surface by processing is less than half the thickness of the processed part compared to before molding, and it is considered that the slight unevenness of the surface affects the fracture. . The formation of texture by agitation is as described in the previous section. In this experiment, since the test piece was cut out with the tool feed direction as the tensile axis, the bottom surface slip easily occurred as reported, and it is considered that the tensile strength was lowered.

(2) AZ31 plate (thickness t = 0.7mm)
The tensile strength of the unprocessed material was 264 MPa, but when the half apex angle was molded at θ = 45 degrees, the tensile strength was slightly reduced to 242 MPa compared to before molding. Similarly, looking at the structure of the processed part, the structure after molding was refined on the front side of the tool press, but was not refined up to the back side. As can be seen from Table 5, since it is thicker than the sample with a plate thickness t = 0.5 mm, the back side is not miniaturized, and it seems that the strength has not been increased. In addition, it is thought that the strength was lowered due to the unevenness of the test piece surface by processing and the formation of texture by stirring.

(3) AZ61 plate (thickness t = 0.5mm)
The raw material had a tensile strength of 301 MPa, but when molded with a half apex angle of θ = 45 degrees, the tensile strength was almost the same as 299 MPa. In the processed part structure, precipitates were confirmed on the tool indentation side and the tool indentation back side by machining.

(4) AZ80 board (thickness t = 0.8mm)
The tensile strength of the unprocessed material was 335 MPa, but when the half apex angle was molded at θ = 45 degrees, the tensile strength was 306 MPa, which was lower than before molding. The microstructure of the machined part was confirmed to be refined on both the tool indentation side and the tool indentation back side, and was very remarkable on the tool indentation side. However, the strength is lower than before molding, as in the case of the two samples of AZ31. Further, there was no difference in tensile strength depending on the extrusion direction.

(Conclusion)
Succeeded in developing a friction stir incremental forming method that forms magnesium alloy sheets that are difficult to form at room temperature at room temperature, forming conditions of AZ31, AZ61, and AZ80 magnesium alloy sheets according to the present forming method, temperature during processing, Comparison with hot incremental forming, and the tensile strength and hardness of the processed plate material were investigated. As a result, the following was found.

  ・ There is a threshold value for the tool rotation speed, and when the threshold value is exceeded, the forming limit height increases rapidly.

  -Optimum molding conditions corresponding to the half apex angle to be molded existed.

  ・ The temperature of the processed part at the time of molding rose to a maximum of about 350 ° C and reached the recrystallization temperature or higher.

  ・ Conventional warm and hot incremental forming can only mold up to half apex angle θ = 35 degrees, but the developed molding method can form up to θ = 25 degrees at the minimum, and moldability is improved. Greatly improved.

  ・ Although the AZ31 alloy sheet had an elongation at break of 26% in a tensile test at room temperature, the elongation of the processed part when forming at a half apex angle of θ = 25 degrees is equivalent to 137%. Was found to improve dramatically. Similarly, AZ61 and AZ80 were able to be molded to an amount of elongation and strain that could not be molded at room temperature.

  ・ The hardness of the processed part after molding was improved when the AZ31 and AZ80 plates were molded at a half apex angle θ = 45 degrees compared to before molding. However, when the AZ31 plate was molded with a half apex angle θ = 25 degrees, and when the AZ61 plate was formed with a half apex angle θ = 45 degrees, a decrease in hardness was observed.

  It was found that the tensile strength when the AZ31 alloy plate was formed at a half apex angle θ = 45 degrees was improved by about 10% compared to the unprocessed material. When the AZ61 and AZ80 alloy plates were formed at a half apex angle of θ = 45 degrees, the tensile strength was kept at least 80% of the unprocessed material, so the tensile strength of the processed part was sufficient.

[II] Aluminum Alloy As a test material, an aluminum alloy A5052-H34 having a thickness of 0.5 mm was used, and a 100 mm square plate was used. Table 6 shows the chemical composition of the test material, and Table 7 shows the physical properties and mechanical properties of the test material.

(A) Relationship between tool movement speed and tool rotation speed (Fig. 25)
FIG. 25 shows the results of investigating the forming conditions by fixing the forming condition at the half apex angle θ = 45 degrees and changing the tool moving speed and the tool rotating speed. Unstable conditions such as ◯ for those that could be molded, x for those that could not be molded, and Δ for those that could not be molded. If the tool rotation speed was increased when the tool moving speed v was 4000 mm / min or less, molding was possible even if the tool moving speed was increased. However, at v = 500 mm / min, the processed part was excessively heated and stirred, and could not be molded. When the tool moving speed was v = 5000 mm / min or higher, forming was impossible despite the high tool rotating speed, and when the tool rotating speed ω = 10000 rpm, forming was impossible.

(B) Relationship between the tool rotational speed ω and the forming limit height of the plate 1 (FIGS. 26 to 28)
FIG. 26 shows the results of investigating the formable height by changing the tool rotation speed while fixing the tool moving speed v = 3000 mm / min and the half apex angle θ = 30 degrees. At the tool rotation speed ω = 0rpm, the NC machine tool stopped and could not be molded because of excessive load. From ω = 2000 rpm, the processed part was broken during the molding, and the molding could only be performed up to a molding height h of about 5 mm. However, when ω = 7000rpm or higher, the molding height improved dramatically, and processing was possible up to h = 20mm, the limit value of the molding height that can be set by the program used. From this, it is understood that the tool rotation speed is greatly related to the moldability, and it is considered that the moldability is improved by increasing the tool rotation speed.

  Therefore, paying attention to the frictional heat due to tool rotation, FIG. 28 shows the results of measuring the temperature of the machined part under the machining conditions of ω = 7000 rpm where the formability is dramatically improved and ω = 6000 rpm just before that. As a result, the maximum temperature during processing at ω = 6000 rpm and ω = 7000 rpm was 273.3 ° C. and 284.9 ° C., respectively, which did not reach the recrystallization temperature (330 ° C.).

(C) Relationship between the tool rotation speed ω and the half apex angle θ at which the plate 1 can be formed (FIGS. 29 to 32)
FIG. 29 shows the results of investigating the forming conditions by fixing the tool moving speed v = 3000 mm / min and changing the tool rotation speed and the half apex angle. In past experiments, it has been reported that A5052-H34 material and 0.6 mm thick incremental forming can be molded up to half apex angle θ = 30 degrees. In this experiment, no lubricating oil was used, but when forming was performed assuming that the tool rotational speed ω = 0rpm was incremental forming, the half apex angle θ was 45 °. When the tool rotation speed is increased, the half apex angle value that can be molded up to ω = 6000 rpm did not change substantially, but when ω = 7000 rpm or more, the half apex angle value can be molded to a small value of θ = 25 degrees. At ω = 10000 rpm, molding was possible up to θ = 20 degrees. This also shows that the tool rotation speed is greatly related to the formability.

  The theoretical relationship between the half apex angle, equivalent strain, and elongation is shown in FIG. This graph shows how much strain is given to the processed part by the molding method of the present invention and how much it is extended. The elongation of the machined part with θ = 45 ° forming is equivalent to approximately 41%, and the elongation of the machined part with θ = 20 ° forming is equivalent to about 192%. It seems to be connected. In addition, photographs of the sample after molding by incremental forming (ω = 0 rpm, θ = 45 degrees) and the sample after molding by the processing method of the present invention (ω = 10000 rpm, θ = 20 degrees) are shown in FIGS. 31 and 32, respectively. Show. A large difference was observed in the molding surface, and the processing method of the present invention was clean compared to the incremental forming. From these facts, it has been found that the processing method of the present invention dramatically improves the moldability in addition to a clean molding surface as compared with the incremental forming.

(D) Relationship between the tool moving speed v and the half apex angle θ in which the plate 1 can be formed (FIG. 33)
FIG. 33 shows the results of investigating the molding conditions with the molding conditions fixed at a tool rotational speed ω = 10000 rpm, the tool moving speed and the half apex angle being changed. When the tool moving speed v = 5000 mm / min or more, molding was not possible at all. Also, there is no difference in the moldable half apex angle at v = 2000-4000mm / min. When v = 1000mm / min or less, the tool moving speed is too slow regardless of the half apex angle, so the heat input / Molding was not possible due to excessive stirring. Although the tool moving speed is a factor in whether or not forming is possible, it is considered that the relationship with formability is weak.

(E) Microstructure observation and processing temperature (Figs. 34 and 35)
FIG. 34 shows a SIM image of a cross-sectional structure formed at a tool moving speed v = 3000 mm / min, a tool rotation speed ω = 7000 rpm, and a half apex angle θ = 45 degrees. 5 μm from the surface became equiaxed grains with a grain size of about 500 nm, and thereafter, the crystal grains became equiaxed grains with a grain size of about 1-2 μm toward the inside. No distortion due to dislocation accumulation was observed in the crystal grains as seen in the raw material. Compared to incremental forming without rotating the tool, the crystal grains were relatively large and the interior was equiaxed grains rather than elongated grains. Such a difference is considered to be a difference in frictional heat during tool rotation. FIG. 35 shows the measurement result of the processing part temperature during processing of the friction stir incremental forming. It can be seen that although the maximum temperature is 233 ° C and has not reached the recrystallization temperature (330 ° C), it is very high. Moreover, since many strains are introduced during molding, it is considered that the environment is likely to cause dynamic recrystallization. The process of miniaturization is the same as incremental forming, but the internal grains do not stretch and become equiaxed grains, not only the surface of the processed part but also the internal temperature is sufficiently high, so every time strain is introduced This is probably because dynamic recrystallization occurred. It is highly possible that the fine crystal grain region on the surface is narrower than the incremental forming material because the grain is grown due to the high temperature of the processing region. Moreover, the thing which was not the crystal grain shown by the white contrast in the vicinity was observed. Probably, the oxide film may have penetrated into the interior by stirring, but the details are unknown.

(F) Change in hardness and structure of machined part (Fig. 36)
The sample is a raw material as a comparative material, an incremental molding material (v = 3000 mm / min, ω = 0 rpm, θ = 45 degrees), and a tool rotation added to the incremental molding conditions (v = 3000 mm) in the processing method of the present invention. / min, ω = 7000 rpm, θ = 45 degrees), and the measurement method of the present invention processing method with the smallest half apex angle (v = 3000 mm / min, ω = 10000 rpm, θ = 20 degrees) The result is shown in FIG.

  The material subjected to incremental molding had a higher hardness than the raw material. Although the processed part is refined by dynamic recrystallization, the inside is deformed during processing and the crystal grains are stretched, so that a large amount of strain remains. From this, it is considered that the hardness of the processed part after the incremental molding was increased by work hardening.

  Both molded with friction stir incremental forming had a lower hardness than the raw material. In the friction stir welding as well, a decrease in the hardness of the processed part has been confirmed. Since the unprocessed materials A5052 and H34 have undergone stabilization after rolling, they contain a large amount of dislocations and are work hardened. From the structure photograph, it can be seen that there is a large amount of strain due to the difference in the intragranular contrast, which also indicates that the raw material is work-hardened. In the friction stir incremental forming, unlike the incremental forming, the tool is rotated at a high speed, so that the frictional heat between the tool and the material during molding increases. In the vicinity of the surface, equiaxed grains having a particle size of about 500 nm were formed, and thereafter, equiaxed grains of about 1-3 μm, which were larger than the vicinity of the surface. It is suggested that dynamic recrystallization occurred continuously in the whole material including the vicinity of the surface, and the crystal grains were refined. From these facts, it is considered that by performing friction stir incremental forming, dynamic recrystallization occurred in the processed part, the strain contained in the unprocessed material was relaxed, and the hardness was lowered.

(G) Tensile strength of the processed part and change in structure (Fig. 37)
Samples as raw material, incremental molding material (v = 3000 mm / min, ω = 0 rpm, θ = 45 degrees), processing method of the present invention (incremental molding conditions plus tool rotation (v = 3000 mm / min, ω = 7000 rpm, θ = 45 degrees)), and the results are shown in FIG.

  The unprocessed material had a maximum tensile strength of 286.2 MPa, and the one that had been incrementally molded had a reduced strength of 232.2 MPa. On the other hand, the friction stir processing method was 239.0 MPa, which was comparable to the incremental molding, although the strength was inferior to that of the raw material.

  Incremental forming material was expected to increase in strength due to work hardening and grain refinement, but was lower than that of unprocessed material. This is because the surface shape of the sample processing part is very bad, stress concentration occurs on a part of the surface, and the strength is lowered from the true value because it breaks from the stress. In the vicinity of the surface of the processed part, since the crystal grains were made fine, the surface was not polished when the tensile test piece was prepared so as not to change the structure.

  The strength of the material formed with the friction stir incremental forming material (v = 3000 mm / min, ω = 7000 rpm, θ = 45 degrees) was lower than that of the unprocessed material. Although the crystal grain in the processed part was refined, an increase in strength was considered, but the reverse behavior was exhibited. During friction stir incremental forming, dynamic recrystallization causes strain relaxation and crystal grain refinement. The decrease in the tensile strength is considered to be due to the effect of the decrease in strength due to the relaxation of strain more prominently than the increase in strength due to crystal grain refinement.

(Conclusion)
In this experiment, aluminum alloy A5052-H34 sheet was formed by friction stir incremental forming, which is a new processing method combining friction stir welding and incremental forming. Processing conditions, temperature measurement during processing, and a hardness test, a tensile test, and a structure observation in the processed part after molding were performed. The results are as follows.

  -There is a well-balanced condition between the tool movement speed and the tool rotation speed that enables forming.

  -Formability is determined by the tool rotation speed. When the rotation speed exceeds a certain rotation speed, the forming limit increases rapidly, and the moldable half apex angle becomes smaller by increasing the tool rotation speed.

  ・ The machining part temperature at the time of forming was the highest at the maximum temperature of 284.9 ° C when the tool moving speed v = 3000mm / min, the tool rotation speed ω = 10000rpm, and the half apex angle θ = 20 degrees among the measured conditions. The crystallization temperature (330 ° C) was not reached.

  ・ When fixed at a tool moving speed of v = 3000 mm / min, incremental forming can form up to a half apex angle of 45 degrees at room temperature, but friction stir incremental forming can form up to a minimum half apex angle of 20 degrees. . The elongation of the processed part was 41% at 45 degrees and 192% at 20 degrees, and formability was dramatically improved by friction stir incremental forming compared to incremental forming.

  ・ The hardness and tensile strength of the processed part after molding by friction stir incremental forming were lower than before molding, but at least the hardness was 75% or more before molding, and the tensile strength was kept 80% or more. It is considered that the hardness and tensile strength are sufficient.

  -The crystal grains of the material were refined by friction stir incremental forming, and the shape was equiaxed grains. In particular, the vicinity of the surface is refined to a grain size of about 500 nm, and the refinement of these crystal grains is thought to be due to dynamic recrystallization during processing.

  Next, when the plate 1 is formed by the tool 20 of the friction stir incremental forming 100, the receiving member 50 (the forming model 51) for supporting the plate 1 is arranged on the back side of the plate 1 in contact with the tool 20, and the forming depth of the plate 1 is increased. The result of investigating the influence on the thickness is shown.

  FIG. 13A (FIG. 13B) is a molding example in which the receiving member 50 (molding model 51) is arranged on the back side of the plate material 1, and FIG. 14A (FIG. 14B) shows the plate material 1. It is a shaping | molding example of the above-mentioned dent space shaping | molding which does not arrange | position the receptacle 50 on a back side. In each forming example, the plate material 1 is made of magnesium alloy AZ31, no forming oil, the tool rotational speed ω, the tool moving speed v, the feed pitch p in the Z-axis direction, and the half apex angle θ are shown in FIG. As described in FIG. 14 (A). According to FIG. 13 (A) (FIG. 13 (B)) and FIG. 14 (A) (FIG. 14 (B)), by arranging the receiving tool 50 (molded model 51) on the back side of the plate 1, the plate 1 It can be seen that the molding depth can be increased from 10 mm to 23 mm up to 2.3 times, and the moldability can be improved.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration of the present invention is not limited to this embodiment, and even if there is a design change or the like without departing from the gist of the present invention. It is included in the present invention.

  The present invention can form a plate material made of an alloy such as a magnesium alloy, an aluminum alloy, a titanium alloy, or a metal at room temperature without using a mold.

DESCRIPTION OF SYMBOLS 1 Board | plate material 10 Board | plate material support apparatus 20 Tool 30 Tool rotation apparatus 40 Movement apparatus 41 Board | plate material movement apparatus 42 Tool movement apparatus 50 Receptacle 51 Molding model

Claims (16)

In a method for forming a plate material in which a plate material made of an alloy or metal is formed into a three-dimensional shape,
A method for forming a plate material, wherein the tool is pressed against the plate material and moved relative to the plate material in a three-dimensional direction while rotating the tool.   The plate material forming method according to claim 1, wherein the plate material is made of a magnesium alloy.   The plate material forming method according to claim 1, wherein the plate material is made of an aluminum alloy.   The plate material forming method according to claim 1, wherein the plate material is made of a titanium alloy.   The method for forming a plate material according to any one of claims 1 to 4, wherein the plate material is formed by causing plastic flow due to frictional stirring caused by rotation of the tool to the plate material in contact with the tool.   The plate material forming method according to claim 5, wherein the tool is in contact with the plate material without forming oil.   The method for forming a plate material according to claim 5 or 6, wherein a receiving tool for supporting the plate material is disposed on the back side of the plate material in contact with the tool.   The plate material forming method according to claim 7, wherein the receiving member is formed of a plate material forming model.   9. The method according to claim 1, wherein the tool is pressed against the plate material and relatively moved over one circumference along the contour line of the three-dimensional shape to be formed of the plate material at various points in the height direction of the plate material. 2. A method for forming a plate material according to 1. In a plate material forming apparatus for forming a plate material made of an alloy or metal into a three-dimensional shape,
A plate material support device for supporting the outer edge of the plate material;
A tool in contact with the plate,
A tool rotating device for rotating the tool;
A plate forming apparatus comprising a tool and a moving device for relatively moving a plate in a three-dimensional direction.   The plate forming apparatus according to claim 10, wherein the plate is made of a magnesium alloy.   The plate forming apparatus according to claim 10, wherein the plate is made of an aluminum alloy.   The plate forming apparatus according to claim 10, wherein the plate is made of a titanium alloy.   The said movement apparatus has the board | plate material movement apparatus which moves a board | plate material to orthogonal two-axis direction, and the tool movement apparatus which moves a tool to the direction orthogonal to each of the said orthogonal two-axis direction of Claims 10-13 The board | plate material shaping | molding apparatus in any one.   The board | plate material shaping | molding apparatus in any one of Claims 10-14 which has a receptacle which is arrange | positioned on the back side of the board | plate material which the said tool contacts, and supports this board | plate material.   The plate material forming apparatus according to claim 15, wherein the receiving member is a plate material forming model.