JP5712448B2 - Metal part having protrusion, method for forming protrusion on metal member, and protrusion forming apparatus - Google Patents

Description

  The present invention relates to a high mechanical strength metal part having protrusions, a method for forming protrusions of the same material on the surface of a metal member by a friction stir processing technique, and a protrusion forming apparatus.

  Forming solid projections on the surface of metal members is widely used as positioning means, support means, fixing / fixing means, cooling means, portable information terminals such as mobile phones and mobile personal computers, home appliances, It has become an indispensable technology for automobile parts and railway vehicles. As a method for forming solid protrusions on the surface of a metal member, the protrusions are prepared in advance and welded, brazed, solid-phase bonded to the metal member, friction bonded, or pressed using a mold. Methods are known and used. The method of welding and brazing has a problem that it cannot be applied to magnesium, magnesium alloy and aluminum, and aluminum alloy, which tend to be used from the viewpoint of increasing manufacturing steps and cost and reducing weight. Has a problem that the dimensional accuracy is poor, and the pressing method cannot be applied when the metal member is downsized, thinned and complicated.

  As a technique for forming a solid protrusion on the surface of a metal member, an aluminum first object is placed on a second object (mold) having a recess, and the first object is brought into contact with a frictional heat generating stirring means. Friction stir molding that generates a frictional heat by causing a relative movement between the first object and a plastic flow in a non-molten state, thereby transferring a convex portion corresponding to a concave portion of the second object to the first object. Method (Patent Document 1) and a magnesium alloy part that forms a convex portion by plastically flowing a part of the raw material plate into a concave portion of the mold by heating the raw material plate between a pair of upper and lower molds. Has been proposed (Patent Document 2). The former friction stir molding method does not require a heat source and fills the concave portion formed in the mold disposed on the side opposite to the stirring means by using plastic flow generated by using frictional heat. Can be eliminated. However, the protrusions formed by this method have low mechanical properties (strength and ductility), and practical problems remain. The reason for this is that, according to the present inventors, the region where the structure is refined is the region where the first object is frictionally stirred by the frictional heat generating stirring means, and the second object is separated from the region. The recess formed in is located, and the structure of the protrusion is not miniaturized. Furthermore, it is difficult to form protrusions having a diameter of 3 mm or more and a height of 5 mm or more on a thin plate (up to 2 mm thick) by this method. The latter manufacturing method makes it possible to form convex portions on a magnesium alloy member that cannot be welded or brazed, and can solve the above-mentioned problems. However, in this method, a heater is incorporated in each of the upper mold and the lower mold, and plastic flow is generated by heating with a heater. In addition to requiring heat energy, the mechanical characteristics of the protrusions are Has the problem of low. The reason is that the plastic energy generated without using agitation has a small strain energy and the structure cannot be sufficiently refined.

JP 2002-256453 A JP 2004-337935 A

  The present inventors previously proposed a method for forming a solid protrusion to solve the above-mentioned problem in Japanese Patent Application No. 2008-183276. This method uses frictional heat generated by pressing the tip of the processing means having an opening at the tip on the surface of the metal member and rotating the metal member and the processing means in opposite directions. The temperature of the portion of the metal member in contact with the means is raised to develop plastic flow under low stress, and the metal member is guided to the opening of the processing means to form a protrusion. For this reason, the protrusion formed by this method has a cylindrical and smooth outer surface. For example, when forming a thread groove to be screwed on the outer surface, an additional step of forming the thread groove after forming the protrusion is added. There is a problem that the manufacturing time is remarkably increased by adding a thread groove forming step of several minutes to the protrusion forming time of several seconds. Further, in the case where the protrusion is formed in a cylindrical shape and a screw is formed on the inner surface, a drilling process and a thread groove forming process are required, and the manufacturing process increases and the manufacturing time becomes longer. Further, when the stopper portion for preventing rotation is formed on the outer peripheral surface of the protrusion or the cylindrical inner peripheral surface, there is a similar problem.

An object of the present invention is to provide a metal part which is made of the same material as that of the metal member, has a screwing and anti-rotation function, and has a protrusion having high mechanical strength.
Another object of the present invention is a method of forming a metal member having a hollow portion made of the same material as the metal member, having at least one opening and extending in the height direction, and forming protrusions having different outer shapes and inner shapes of the hollow portions substantially simultaneously. It is to provide.
Another object of the present invention is to form a protrusion on a metal member that is made of the same material as that of the metal member and that has a hollow portion that is open at least one and extends in the height direction, and the protrusion having a different outer shape and a different inner shape of the hollow portion is formed substantially simultaneously. To provide an apparatus.

  The feature of the metal part having a protrusion according to the present invention is that the metal member and the surface of the metal member are integrally formed of the same material as that of the metal member and have a protrusion, and the protrusion has a hollow portion that opens at least one side and extends in the height direction. In addition, the outer shape of the protrusion and the inner shape of the hollow portion are different, and the surface area of the protrusion and the metal member in the vicinity thereof is a finer structure than the other areas. The outer shape of the protrusion and the inner shape of the hollow portion are different from each other, for example, (1) one in which a thread groove is formed on either the outer surface of the protrusion or the inner surface of the hollow portion, and (2) the outer surface of the protrusion. Or a cross section perpendicular to the height direction of one of the projections on the inner surface of the hollow portion is a perfect circle and the other has a shape other than a perfect circle, (3) the projection of the outer surface of the projection or the inner surface of the hollow portion The cross section perpendicular to the height direction is substantially the same, and a protrusion, a groove, a notch, or the like is formed on either side. The metal part having the protrusion is suitable for use as a part having a protrusion used for a portable information terminal, a home appliance, an automobile part, a railway vehicle, or the like.

  The feature of the first method of forming the protrusion on the metal member of the present invention is that a step of preparing a processing jig in which a through hole having a thread groove is formed on the inner peripheral surface, and the processing jig is mounted on the metal member. A step of placing, a rotating tool having a smaller diameter guided to the through hole of the processing jig, contacting the metal member, and rotating with the rotating tool being pressed against the metal member, frictional heat between the rotating tool and the metal member There is a step of filling the metal member between the through hole of the processing jig and the rotary tool by the plastic flow of the metal member caused by the above. When a rotating tool is pressed against a metal member and the rotating tool is rotated, frictional heat is generated, and this frictional heat raises the temperature of the portion of the metal member that is in contact with the rotating tool, thereby causing plastic flow under low stress. When the metal member flows into the gap including the screw groove formed between the through hole and the rotary tool, and the rotation of the rotary tool stops when the surrounding area where the plastic flow of the metal member does not appear and becomes a stopper The temperature of the metal member decreases and the plastic flowed portion is cured, and a protrusion having a thread groove on the outer peripheral surface is formed on the metal member. When the plastic flowed part is hardened, the rotary tool is pulled out from the through hole, and at least one of the processing jig or metal member is rotated in the direction to release the threading of the processing tool screw groove and the protruding screw groove. Release the protrusion from the jig. Plastic flow occurs when the metal member is in a solid state, so that the structure of the metal member does not become coarse. On the other hand, the surface area of the protrusion and the metal member in the vicinity thereof is finer than other areas due to frictional stirring of the rotary tool. Therefore, superplastic flow occurs in the high temperature state during processing (the temperature of the melting point of the metal member expressed as 1/2 or more of the absolute value), the deformation stress is small, and the plastic fluidity Is very big. On the other hand, the mechanical strength of the protrusion when the temperature returns to room temperature after the end of processing can be increased.

  A feature of the second method of forming the protrusion on the metal member of the present invention is that a step of preparing a processing jig having a cylindrical portion having a thread groove on the outer periphery is provided, and the cylindrical portion of the processing jig is protruded. A step of placing a metal member having a hole through which the cylindrical portion penetrates, a rotating tool having a hole having a diameter larger than the cylindrical portion of the processing jig placed on the metal member and rotating The metal member is placed between the cylindrical portion of the processing jig and the hole of the rotating tool by the process of rotating the tool while pressing the metal member, and the plastic flow of the metal member caused by frictional heat between the rotating tool and the metal member. It is in the point provided with the process of filling. When a rotating tool is pressed against a metal member and the rotating tool is rotated, frictional heat is generated, and this frictional heat raises the temperature of the portion of the metal member that is in contact with the rotating tool, thereby causing plastic flow under low stress. The metal member flows into a gap including a screw groove formed between the cylindrical portion of the processing jig and the hole portion of the rotary tool. When the rotation of the rotary tool is stopped, the temperature of the metal member decreases and the plastic flowed portion is cured, and a hollow protrusion having a thread groove on the inner peripheral surface is formed on the metal member. When the plastic flowed portion is cured, the rotary tool is pulled away from the hollow protrusion, and at least one of the processing jig or the metal member is rotated in a direction to release the screw groove of the processing jig and the screw groove of the hollow protrusion, Release the protrusion from the processing jig. Even in this case, the mechanical strength of the hollow protrusion can be increased for the same reason as in the first method.

The feature of the third method of forming the protrusion on the metal member of the present invention is that a step of preparing a processing jig in which a through hole having a predetermined shape is formed, a step of placing the processing jig on the metal member, a processing A rotating tool having a shape formed in the through hole of the jig by rotation and having a shape different from that of the through hole, contacting the metal member, and rotating the rotating tool while pressing the metal member; The metal member is filled with the metal member between the through hole of the processing jig and the rotary tool by plastic flow of the metal member caused by the frictional heat of the metal member. When a rotating tool is pressed against a metal member and the rotating tool is rotated, frictional heat is generated, and this frictional heat raises the temperature of the portion of the metal member that is in contact with the rotating tool, thereby causing plastic flow under low stress. When the metal member flows into the gap formed between the through hole and the rotary tool, and the surrounding area where the plastic flow of the metal member does not occur becomes a stopper, the temperature of the metal member stops when the rotation of the rotary tool stops. As a result, the portion that has undergone plastic flow is hardened, and a protrusion having a hollow portion that is open at one end having a different outer shape and inner shape is formed on the metal member. Even in this case, the mechanical strength of the hollow protrusion can be increased for the same reason as in the first method.

  The metal member to which the method of forming protrusions on the metal member of the present invention is applied is not limited to these, but a magnesium alloy and an aluminum alloy are preferable. Examples of magnesium alloys include magnesium alloys containing at least one kind of aluminum Al, zinc Zn, zirconium Zr, manganese Mn, lithium Li, iron Fe, silicon Si, copper Cu, nickel Ni, calcium Ca, and rare earth elements. Examples of the aluminum alloy include an aluminum alloy containing at least one kind of copper Cu, manganese Mn, silicon Si, magnesium Mg, zinc Zn, nickel Ni, chromium Cr, and titanium Ti.

  The protrusion forming device of the present invention is characterized by a holding means for holding a metal member to be processed, a rotating tool means for generating frictional heat by rotating in contact with the metal member, and a rotating tool means. A processing jig for forming a cylindrical gap for filling the metal member by plastic flow, a means for rotating the rotary tool means, and at least one of the holding means and the rotary tool means along a line connecting the two means. It is in the point which comprises the means to move, and the means to press a rotary tool means on the metal member surface. According to this projection forming apparatus, it has a hollow portion at least one of which is opened by a plastic flow expressed by frictional heat between the rotating tool means and the metal member, and a gap shape formed by the processing jig and the rotating tool means, For example, it is possible to provide a metal part having a protrusion whose outer shape is different from the shape of the inner surface of the hollow portion in a very short time such as several seconds. This protrusion forming apparatus may be a single function apparatus that forms protrusions on a metal member, or may be an apparatus portion that performs one process among a plurality of processes of a progressive press apparatus.

The processing jig used in the projection forming apparatus of the present invention is required to have low heat resistance, wear resistance, and wettability (does not adhere to the workpiece), and specific materials include stainless steel (for example, SUS steel), tool steel (e.g. SK steel), superalloy (Ni-based, Fe-based, Co-based), ceramics (CBN (cubic boron _{nitride), ZrO 2, SiC, Si} 3 N 4, SiALON, Al 2 O 3 and their A composite material of metal and ceramics (for example, cermet).

The metal part having the projection according to the present invention has a hollow portion having at least one of the same material opened on the surface of the metal member, and has a projection having a different outer shape and an inner surface shape of the hollow portion. It has a non-rotating function and can be used for a wide range of applications, and the surface area of the protrusion and the metal member near it has a finer structure than other areas, realizing a protrusion with excellent mechanical properties. it can.
Further, according to the method of forming the protrusions on the metal member of the present invention, the plastic tool is used between the rotating tool and the processing jig by utilizing the plastic flow of the metal member due to the superplasticity generated by frictional heat and friction stirring between the rotating tool and the metal member. Since the method of filling the gap formed in the metal is used, it is possible to form protrusions with the same material as the metal member and having a fine structure in the surface region in a short time of several seconds, and it is possible to realize protrusions with excellent mechanical properties. .
Furthermore, the projection forming apparatus of the present invention has a hollow portion made of the same material as that of the metal member on the surface of the metal member without applying heat energy from the outside, at least one of which is open, and has an outer shape and an inner shape of the hollow portion. Different protrusions can be formed by plastic flow.

It is a schematic sectional drawing which shows the 1st Example of the metal component which has this invention protrusion. It is a schematic sectional drawing which shows the 2nd Example of the metal component which has this invention protrusion. It is the schematic sectional drawing and schematic plan view which show the 3rd Example of the metal component which has this invention protrusion. It is a schematic sectional drawing explaining the 1st Example of the method of forming protrusion on this invention metal member. It is a schematic enlarged view explaining the effect | action of the method of forming protrusion in this invention metal member. It is a general | schematic cross-sectional degree explaining the point with the high mechanical characteristic of the protrusion formed in the metal member by the method of this invention. It is a microscope picture which shows the structure | tissue state of the base part of the processus | protrusion formed in the metal member by the method of this invention. It is a schematic sectional drawing explaining the 2nd Example of the method of forming protrusion on this invention metal member. It is a schematic sectional drawing explaining the 3rd Example of the method of forming protrusion on this invention metal member. It is a schematic plan view which shows another Example of the metal component which has this invention protrusion. It is the schematic front view and side view which show an example of the protrusion formation apparatus used in order to perform the method of forming a protrusion in this invention metal member.

  The metal part having protrusions according to the present invention has a protrusion formed integrally on the surface of an aluminum alloy and a magnesium alloy with the same material as that of the metal member. At least one of the protrusions has a hollow portion extending in the height direction. In addition, the outer shape of the protrusion and the inner shape of the hollow portion are different, and the surface region of the protrusion and the metal member in the vicinity thereof has a finer structure than the other regions. The simplest method for forming hollow protrusions on the surface of a metal member is to place a processing jig and a rotary tool that determine the shape of the protrusion on one side of the metal member, and use plastic flow by frictional stirring of the rotary tool. It is a simple method. Magnesium and magnesium-based alloys are lightweight metal materials and tend to be widely used as metal parts such as portable information terminals, home appliances, automobile parts, and railway vehicles.

FIG. 1 is a schematic sectional view showing a first embodiment of a metal part having protrusions according to the present invention. A metal part 11 is composed of a plate-like metal member 111 and a protrusion 112 integrally formed on the surface of the metal member 111. . The protrusion 112 has a bottomed, cylindrical hollow portion with a thread groove 112a formed on the outer peripheral surface, and the bottom portion 111a is thinner than the metal member 111 because the protrusion is formed using a friction stir processing technique. . Since the protrusion 112 has a thread groove 112a formed on the outer peripheral surface, the shape of the inner peripheral surface is different from the shape of the outer peripheral surface. Metal parts 11 having the protrusion 112 for utilizing screwed when attached to another member, disconnect the coupling at the time of inspection and repair, there is the advantage that it is possible you bond again. In addition, since the inner peripheral surface including the bottom 111a of the protrusion 112 and the vicinity thereof have a finer structure than other regions, a protrusion having excellent mechanical characteristics can be realized. The bottom 111a contributes to improving the aesthetics of the surface opposite to the side on which the projection 112 of the metal member 111 is formed and maintaining high strength, but when the metal member 111 needs to be provided with a through hole, A structure in which the bottom 111a does not exist can be obtained at the expense of some beauty and strength.

  FIG. 2 is a schematic cross-sectional view showing a second embodiment of a metal part having protrusions according to the present invention. The metal part 11 is composed of a plate-like metal member 111 and a protrusion 113 integrally formed on the surface of the metal member 111. . The projection 113 has a cylindrical hollow portion without a bottom in which a thread groove 113a is formed on the inner peripheral surface, and a portion 111b adjacent to the projection 113 of the metal member 111 forms a projection using a friction stirring process technique. It is thinner than other parts. Since the protrusion 113 also has a thread groove 113a formed on the inner peripheral surface, the shape of the inner peripheral surface is different from the shape of the outer peripheral surface, and screwing is used for coupling with other members. It has the same advantages as the protrusions. In addition, since the outer peripheral surface of the protrusion 113 and the surface of the portion 111b and the vicinity thereof have a finer structure than other regions, a protrusion having excellent mechanical characteristics can be realized.

  FIG. 3 is a schematic cross-sectional view showing a third embodiment of the metal part having the projection of the present invention. The metal part 11 is composed of a plate-like metal member 111 and a projection 114 formed integrally with the metal member 111. The protrusion 114 has a bottomed cylindrical hollow portion and a prismatic outer peripheral surface, and as a result, as shown in FIG. 3B, an inner peripheral surface whose cross section perpendicular to the height direction of the protrusion forms a perfect circle. It has the outer peripheral surface 114b which makes a substantially square shape with 114a. The cylindrical space formed by the inner peripheral surface 114 a of the protrusion 114 has a bottom on the metal member side 111 side and a bottom portion 111 c thinner than the metal member 111 because the protrusion 114 is formed using the friction stirring process technique. . Since the protrusion 114 has a shape different from the shape of the inner peripheral surface 114a and the shape of the outer peripheral surface 114b, the protrusion 114 has an advantage of preventing rotation on a surface perpendicular to the height direction of the protrusion of the coupling portion using the protrusion 114. Yes. In addition, since the inner peripheral surface including the bottom 111c of the protrusion 114 and the vicinity thereof have a finer structure than other regions, a protrusion having excellent mechanical characteristics can be realized. The bottom 111c contributes to improving the aesthetics of the surface opposite to the side on which the protrusion 114 of the metal member 111 is formed and maintaining high strength. However, when it is necessary to provide a through hole in the metal member 111, A structure in which the bottom 111c does not exist can be obtained at the expense of some aesthetics and strength.

  FIG. 4 is a schematic sectional view for explaining a first embodiment of a method for forming a protrusion on a metal member. 111 is a plate-shaped metal member, 12 is a processing jig having a through-hole 121 with a thread groove 121a formed on the inner peripheral surface, 13 is a tip 13a having a smaller diameter than the through-hole 121 of the processing jig 12, for example, is substantially flat. In order to manufacture the metal part 11 having the protrusion 112 shown in FIG. 1 with a simple rotating tool, it is necessary to prepare them. When forming protrusions on the metal member 111, the metal member 111 is placed at a predetermined position on a processing table (not shown) and fixed by mechanical, electrostatic or vacuum suction, and the protrusion of the metal member 111 is fixed. The processing jig 12 is placed on the metal member 111 with the through-hole 121 of the processing jig 12 being positioned at a place to be formed (FIG. 4A). At this time, the rotary tool 13 is in a standby state in the vicinity of the through hole 121 of the processing jig 12. Next, the rotating tool 13 is guided into the through hole 121 of the processing jig 12 while rotating, and the tip 13a is pressed against the surface of the metal member 111 with a predetermined pressure. When the front end portion 13a of the rotary tool 13 is rotated and pressed against the surface of the metal member 111, the structure of the surface region of the metal member 111 that is in contact with the front end portion 13a of the rotary tool 13 is increased due to the temperature rise due to frictional heat. Is softened, is easily stirred by the rotation of the rotating tool 13 under pressure, enters a high strain processing state, and is refined by dynamic recrystallization or the like. The microstructure thus refined exhibits a superplastic phenomenon that facilitates plastic deformation at high temperatures. Due to the development of the superplastic phenomenon, plastic flow occurs, and further, even in a non-miniaturized region, it softens and plastically flows under high temperature conditions. As will be described later, the plastic flow flows toward the gap formed between the inner peripheral surface of the through-hole 121 of the processing jig 12 and the rotary tool 13, and fills the gap including the screw groove 121a so that the projection 112 is formed. It forms (FIG.4 (b)). The rotary tool 13 and the processing jig 12 are separated from the metal member 111, and the metal part 11 having the protrusion 112 shown in FIG. 1 is obtained (FIG. 4C). In order to separate the processing jig 12 from the metal member 111, the screw groove 121 a formed in the through hole 121 of the processing jig 12 and the screw groove 112 a of the hollow protrusion 112 formed on the surface of the metal member 111 thereby are screwed together. It is necessary to rotate both in the direction to release the screwing of both.

A method of forming a projection on a metal member shown in FIG. 4, by you pressing the rotary tool 13 to the other surface of the metal member 111 in FIG. 4 (b), it is possible to obtain a structure in which the bottom portion 111a is not present. In that case, it is necessary to set the interval between the through hole 121 of the processing jig 12 and the rotary tool 13 so that the rotary tool 13 is substantially filled by plastic flow when the rotary tool 13 passes through the metal member 111. .

The reason why the protrusions are formed by plastic flow will be described with reference to FIG. FIG. 5 is an enlarged view of FIG. 4B, and the surface region 111a of the metal member 111 in contact with the tip 13a of the rotary tool 13 develops a superplastic phenomenon, and the plastic flow is indicated by a black arrow. The state which has arisen in the direction Y111a is shown. On the other hand, the lower region where stirring does not occur is softened due to the temperature rise due to frictional heat, and plastic flow is generated in the white arrow direction Y112a by the pressing force of the rotary tool 13 (similar to normal hot forming). Surface area 111a of the metal member 111 expressing superplastic phenomena is that side it is pressed in the Y1 1 direction is surrounded by a surrounding region 111b that do not express the superplastic phenomena, upward rotation tool 13 Are pushed in the directions of arrows Y13 and Y12 by the front end portion 13a and the processing jig 12, and are pressed in the directions of the black arrows Y111a and white arrows Y112a, and the through holes 121 of the processing jig 12 indicated by the black arrows Y111b and white arrows Y112b between gap direction of the rotary tool 13 is only in the flow direction and. The flow into between gap in proportion to the time the friction stirring by the rotation tool 13 is continued continued, the height of the protrusion 112 is increased.

An important matter in the method of forming protrusions on the metal member of the present invention is the setting of processing conditions. When magnesium, a magnesium-based alloy, aluminum, and an aluminum-based alloy are processed as metal members to be processed at room temperature, the processing jig has a rotation speed of 200 to 20000 rpm, preferably 200 to 5000 rpm, and an indentation pressure of 50 kg / cm ² or more is preferable. .

The point that the mechanical characteristics of the protrusion formed on the metal member by the method of the present invention is excellent will be described with reference to FIG. The region of the metal member 111 that has been frictionally stirred by the rotating tool 13 is refined (expression of dynamic recrystallization or the like). Miniaturized region becomes easy plastic deformation at high temperature, resulting plastic flow superplastic phenomena is expressed, the gap including a thread groove formed with the through hole 121 of the jig 12 by the rotary tool 1 3 A projection 112 having a thread groove is formed. The areas indicated by hatching in the vicinity of the inner peripheral surface and the bottom surface of the protrusion 112 in FIG. 6 are areas having a structure refined by friction stirring. As the structure is refined, the mechanical properties generally improve. When a protrusion is formed on a metal member, stress concentration occurs at a connection portion between the metal member and the protrusion, and mechanical breakage often occurs at this portion. When the protrusion is formed by the method of the present invention, since the refined structure exists from the protrusion to the metal member beyond the connecting portion between the protrusion and the metal member, the mechanical strength can be improved.

  FIG. 7 is a photomicrograph showing the tissue state of the base portion of the protrusion formed by the method of forming the protrusion of the present invention (the connecting portion between the protrusion 112 and the bottom 111a in FIG. 6). From the photograph, it can be seen that the structure of the portion corresponding to the hatched region in FIG. 6 is miniaturized as compared with the others.

  When the impact value which is one of the mechanical properties of the protrusion formed by the method of forming the protrusion of the present invention was measured, the following result was obtained. The tester uses an Izod impact tester (WR = 3 kg · m) from Tester Sangyo Co., Ltd., and the impact value of the sample before forming the protrusion and the sample having the protrusion formed under the same conditions at room temperature (20 ° C). As a result of measurement, it was confirmed that in both cases of AZ31 and ZK60A, the case where the protrusion was formed had a larger value than the impact value of the material.

  An alternative technique is conceivable for forming the protrusions on the metal member shown in FIG. 4 in that screw grooves are formed on the outer peripheral surface of the protrusions. As an alternative technique, for example, the metal member 111 is placed on the processing jig 12 having the through-hole 121 in which the thread groove 121 a is formed on the inner peripheral surface, and the rotating tool is placed on the metal member 111 corresponding to the through-hole 121. A method of pressing while rotating 13 is conceivable. This alternative technique has the following problems compared to the method of the present invention. (1) Microstructural refinement by friction stirring and subsequent development of superplasticity occurs on the surface side of the metal member in contact with the rotating tool, thereby facilitating plastic flow and forming protrusions. The gap formed between the through hole 121 and the rotary tool 13 is smoothly filled by plastic flow. However, in the alternative technique, superplastic flow is developed in the entire plate thickness direction, and plastic flow is facilitated. As a result, there is a problem that it is difficult to form projections as designed. (2) In relation to the above (1), the present invention can form protrusions regardless of the thickness of the metal member, but the alternative technique has a problem that the protrusion cannot be formed unless the metal member is thin. If the plate pressure is small, there is a problem that the height and thickness of the protrusions are insufficient, and practical protrusions cannot be formed. (3) Since the protrusion formed on the metal member is used for coupling with other members, it is a normal usage that the back surface on which the protrusion is formed is the front side of an automobile, an electric product or the like. In the present invention, since the back side on which the protrusion is formed is a flat surface, there is no problem in aesthetics of the product. However, in the alternative technique, a hole formed with a rotating tool remains on the back side on which the protrusion is formed, and there is a problem in aesthetics. (4) In the present invention, since the rotary tool and the processing jig used for forming the protrusion are arranged on one side of the metal member, the alignment work is easy and the protrusion can be easily formed even when the metal member becomes large. In the alternative technique, since the rotary tool and the processing jig are located on both sides of the metal member, it is difficult to align them, and there is a problem that the projection forming apparatus becomes large when the metal member has a large size.

  FIG. 8 is a schematic cross-sectional view for explaining a second embodiment of a method for forming protrusions on a metal member. 111 is a plate-shaped metal member in which a through-hole 11a is formed in advance at a position where a protrusion is formed, 12 is a processing jig having a flat plate portion 12a and a cylindrical protrusion 122 having a thread groove 122a on the outer peripheral surface, and 13 is a processing tool. A metal part having a cylindrical hollow portion 13b having a diameter larger than the outer diameter of the protrusion 122 of the jig 12 and deeper than the height of the protrusion 122, the tip portion 13a being a substantially flat rotating tool, and having the protrusion 113 shown in FIG. When manufacturing 11, it is necessary to prepare these. When forming a protrusion on the metal member 111, the processing jig 12 is placed at a predetermined position on a processing table (not shown) with the protrusion 122 facing upward and fixed by mechanical, electrostatic or vacuum suction. The metal member 111 is placed on the processing jig 12 so that the projection 122 of the processing jig 12 penetrates through the through hole 11a (FIG. 8A). At this time, the rotary tool 13 is in a standby state above the protrusion 122 of the processing jig 13. Next, while rotating the rotary tool 13, the tip portion 13 a is pressed against the surface of the metal member 111 with a predetermined pressure so as to guide the projection 122 of the processing jig 12 into the cylindrical hollow portion 13 b. When the front end portion 13a of the rotary tool 13 is rotated and pressed against the surface of the metal member 111, the structure of the surface region of the metal member 111 that is in contact with the front end portion 13a of the rotary tool 13 is increased due to the temperature rise due to frictional heat. Is softened, is easily stirred by the rotation of the rotating tool 13 under pressure, enters a high strain processing state, and is refined by dynamic recrystallization or the like. The microstructure thus refined exhibits a superplastic phenomenon that facilitates plastic deformation at high temperatures. Due to the development of the superplastic phenomenon, plastic flow occurs, and further, even in a non-miniaturized region, it softens and plastically flows under high temperature conditions. The plastic flow flows toward the gap formed between the projection 122 of the processing jig 12 and the rotary tool 13, and fills the gap including the thread groove 122a to form the projection 113 (FIG. 8B). . Thereafter, the rotary tool 13 and the processing jig 12 are separated from the metal member 111, and the metal part 111 having the protrusion 113 shown in FIG. 2 is obtained (FIG. 8C). In order to separate the processing jig 12 from the metal member 111, the thread groove 122a formed in the protrusion 122 of the processing jig 12 and the thread groove 113a of the protrusion 113 formed on the surface of the metal member 111 by this are screwed. It is necessary to rotate both in the direction to release the screwing of both.

  In the outer peripheral surface of the protrusion 113 formed in this embodiment and the portion 111b where the thickness of the metal member 111 adjacent thereto is reduced, the region frictionally stirred by the rotary tool 13 is miniaturized and the mechanical characteristics are improved. It is an area. Therefore, a metal component having a protrusion having a hard mechanical strength can be obtained.

FIG. 9 is a schematic cross-sectional view for explaining a third embodiment of a method for forming protrusions on a metal member. 111 is a plate-shaped metal member, 12 is a processing jig having a substantially square through-hole 123, 13 has an outer diameter that can be guided to the through-hole 123 of the processing jig 12, and is higher than the depth of the through-hole 123. When the metal part 11 having the protrusions shown in FIG. 3 is manufactured using a rotary tool having a substantially flat tip portion 13a, it is necessary to prepare them.
When the protrusion 114 is formed on the metal member 111, the metal member 111 is placed at a predetermined position on a processing table (not shown) and fixed by mechanical, electrostatic or vacuum adsorption. The processing jig 12 is placed on the metal member 111 with the through-hole 123 of the processing jig 12 being aligned with the planned position where the material is to be formed (FIG. 9A). At this time, the rotary tool 13 is in a standby state above the through hole 123 of the processing jig 13. Next, the rotating tool 13 is guided into the through hole 123 of the processing jig 12 while rotating, and the tip end portion 13a is pressed against the surface of the metal member 111 with a predetermined pressure. When the front end portion 13a of the rotary tool 13 is rotated and pressed against the surface of the metal member 111, the structure of the surface region of the metal member 111 that is in contact with the front end portion 13a of the rotary tool 13 is increased due to the temperature rise due to frictional heat. Is softened, is easily stirred by the rotation of the rotating tool 13 under pressure, enters a high strain processing state, and is refined by dynamic recrystallization or the like. The microstructure thus refined exhibits a superplastic phenomenon that facilitates plastic deformation at high temperatures. Due to the manifestation of the superplastic phenomenon, plastic flow is facilitated, and further, even in a region that is not miniaturized, it softens and plastically flows under high temperature conditions. As will be described later, the plastic flow flows toward the gap formed between the inner peripheral surface of the through hole 123 of the processing jig 12 and the rotary tool 13, and fills the gap to form the protrusion 114 (FIG. 9). (B)). Thereafter, the rotary tool 13 and the processing jig 12 are separated from the metal member 111, and the metal part 111 having the protrusion 114 shown in FIG. 3 is obtained (FIG. 9C).

  Since the inner peripheral surface including the bottom portion 111c of the protrusion 114 formed in this embodiment and the vicinity thereof have a finer structure than other regions, a protrusion having excellent mechanical characteristics can be realized. Therefore, a metal part having protrusions with good mechanical strength can be obtained.

A method of forming a projection on a metal member shown in FIG. 9, by you pressing the rotary tool 13 to the other surface of the metal member 111 in FIG. 9 (b), it is possible to obtain a structure in which the bottom part 111c does not exist. In that case, it is necessary to set the interval between the through hole 123 of the processing jig 12 and the rotary tool 13 so that the rotary tool 13 is substantially filled by plastic flow when the rotary tool 13 passes through the metal member 111. .

  FIG. 10 is a schematic plan view showing a different embodiment of the metal part having the protrusion shown in FIG. (A) is an example in which the cross section perpendicular to the height direction of the protrusion has an inner peripheral surface 114a that forms a perfect circle and the outer peripheral surface 114b that forms an ellipse, and (b) is a cross section that forms a right angle to the height direction of the protrusion. (C) is a cross-section perpendicular to the height direction of the protrusion, in which an example includes an inner peripheral surface 114a and an outer peripheral surface 114b that form a perfect circle, and a part of the outer peripheral surface 114b has a portion 114c cut out by a straight line. (D) is an example in which a cross section perpendicular to the height direction of the protrusion forms a perfect circle. (E) shows an example in which a protrusion 114e is formed on a part of the outer peripheral surface 114b, and the cross section perpendicular to the height direction of the protrusion forms a perfect circle and is wider than the inner peripheral surface 114a. An example having an outer peripheral surface 114b having a cross shape is shown in FIG. Section forming a height direction and a right angle respectively show examples having an outer peripheral surface 114b forming the inner peripheral surface 114a and the hexagon forming a perfect circle. In (b), (c) and (d), a plurality of cut shapes, notches, and protrusions may be provided or combined. These are representative examples, and are not limited to these. The hexagonal outer peripheral surface 114b shown in (f) is an example of a polygon, and is not limited to this. For example, if it falls within the category of a polygon such as a quadrangular, octagonal, or dodecagonal shape. Either may be used. When the outer surface is made polygonal, there is an advantage that metal filling by plastic flow is sufficiently performed to every corner and a high-strength protrusion can be formed.

  FIG. 11 is a schematic front view and a side view showing an example of a protrusion forming apparatus used for executing the method of forming protrusions on the metal member of the present invention. In the figure, 51 is a base on which the apparatus is installed, 52 is a frame fixed to the base 51, 53 is a work holding head supported by the frame 52 so as to be movable in the XY direction on a horizontal plane, and 531 is a work holding head 53. A temperature / pressure sensor 54 embedded in the vicinity of the surface is driven by a drive motor (not shown) with a drive shaft that moves the work holding head 53 in the vertical direction. 55 is a work holder supported by the work holding head 53, 56 is a rotary tool shown in FIGS. 4, 8 and 9, 57 is a tool holder for holding the rotary tool 56, and 58 is a tool holder that supports the tool holder 57 and a tool holder. A tool holder drive motor that moves the tool 57 in the vertical direction, 581 is a constant speed / low load control device supported by the tool holder drive motor, 59 is supported by the frame 52, supports the tool holder drive motor 58, and rotates the tool 56. It is a tool rotation motor which rotates.

  When forming a protrusion on the metal member using the protrusion forming apparatus having such a configuration, the metal member and the processing jig are placed and fixed on the work holder 55, and the work holding head 53 is moved in the XY directions. The position where the protrusion of the metal member is formed is opposed to the rotary tool 56. Next, the tool holder 57 is moved downward by the tool holder drive motor 58 while rotating the rotary tool 56 by the tool rotation motor 59, and the rotary tool 56 is brought into contact with the metal member surface with a predetermined pressure. As a result, a plastic flow is generated on the surface of the metal member by frictional heat to form protrusions. When the protrusion is formed, the tool holder 57 is moved upward by the tool holder driving motor 58 to separate the rotating tool 56 from the metal member and the protrusion, and the tool rotating motor 59 is stopped to stop the rotating tool 56.

  Pressure control and position control can be used as a control method for bringing the rotary tool 56 into contact with the metal member surface at a predetermined pressure. Although pressure control has the advantage that stable boss height control is possible by a constant load, there is a drawback that the system configuration is complicated. Specifically, it is realized by mounting a strain gauge and a load cell on a stage and a rotating shaft. In addition, a change in the load applied during boss molding can be considered due to thermal effects, and this countermeasure is necessary. Position control can be realized by controlling the stage and the rotation axis with a servo motor or the like, and has an advantage that the control is relatively easy. However, if the thickness of the workpiece to be provided is not uniform, there is a drawback that the boss dimensional accuracy (height) is lowered. As a solution, there is a method in which the thickness is always controlled by a laser displacement meter and the position is adjusted for each boss molding.

  The method for forming protrusions on the metal member of the present invention, the protrusion forming apparatus, and the metal part having the protrusions manufactured thereby are not limited to the methods and configurations described in the embodiments, but are technical ideas of the present invention. Various modifications can be made within the range.

11 Metal parts,
111 metal members,
112, 113, 114 protrusion,
12 processing jigs,
13 Rotating tool,
112a, 113a13a thread groove,
114a inner peripheral surface,
114b outer peripheral surface

Claims (2)

A metal member having a hole through which the cylindrical part penetrates is placed on the side of the cylindrical part projecting from the cylindrical part having a cylindrical part having a thread groove on the outer periphery, and the cylindrical part of the processing jig part has a large-diameter hole portion from, placed so that the tip portion of the hole portion comes into contact with the Tan Taira rotational tool on the metal member, in a state where the rotary tool is pressed to the metal member is rotated, it is formed integrally with identical material to the surface of the metal member and the metal member, which is formed by the plastic flow of the metal member to which the tip is caused by the frictional heat of the metal member and the Tan Taira rotation tool projections Forming a threaded state with a threaded groove of the processing jig on the inner circumferential surface of the projection by the plastic flow and the round surface formed on the outer circumferential surface of the projection by the plastic flow, and screwing Thread groove formed in the direction to release, both open and extend in the height direction Wherein in a state where the inner shape different outer shape as the hollow portion of the projection is exposed circularity surface and the thread groove of the both shape and surface area of the metal member of the collision caused by other regions and has a hollow portion A metal part having a protrusion, characterized by having a finer structure. A step of preparing a processing jig having a cylindrical portion having a thread groove on the outer periphery;
Placing a metal member having a hole through which the cylindrical portion penetrates on the side of the processing jig on which the cylindrical portion protrudes;
It has a large-diameter hole portion from the cylindrical portion of the processing jig was placed so that the tip portion of the hole portion comes into contact with the Tan Taira rotational tool on the metal member, the metal the rotary tool A step of rotating in a state where the member is pressurized,
The plastic flow of the metal member caused by frictional heat of the metal member and the rotating tool, to the outer surface by filling the metal member between the hole of the said and the cylindrical portion of the processing tool rotating tool Forming a protrusion having a perfect circular surface and having a thread groove formed on the inner peripheral surface in a direction in which the thread groove of the processing jig is screwed and released;
The projections are opened from the processing jig, both have a hollow portion that opens and extends in the height direction, and the outer shape of the projection and the round shape of both shapes in a state where the inner shape of the hollow portion is different from each other, Exposing the thread groove,
A method for forming a protrusion on a metal member.

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