JP2003048083A - Rotary tool, and treating method and surface treatment method of member using the rotary tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent any non-filled defect by increasing the effect of pressing a base metal structure in plastic flow by the friction stirring and joining operation into a stock. SOLUTION: A protruded part 2 and a shoulder part 3 of a rotary tool 4 are formed of a steel such as tool steel and stainless steel of the hardness higher than that of an aluminum alloy, and a spiral groove 2a of the predetermined pitch is formed on an outer circumferential part of the protruded part 2. A spiral groove for guiding the base metal structure in plastic flow by the friction heat by the rotation of the tool into the protruded part 2 in a center part while pressing the base metal structure inside the stock is formed in an end face in contact with the work surface at the shoulder part 3, and the depth of the spiral groove becomes shallower toward a root part to the shoulder part 3 at the protruded part 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to, for example, a rotary tool for treating an aluminum alloy casting, a method for treating a member and a method for surface treatment using the rotary tool.

[0002]

2. Description of the Related Art Japanese Unexamined Patent Publication No. 10-183316 discloses
Disclosed is a surface treatment method for surface treatment of a casting such as a mating surface for a cylinder block of a cylinder head, in which a rotating tool provided with a protrusion on a shoulder portion of the tip is pushed in while rotating, and agitated in a non-molten state by heat. ing.

[0003]

In the surface treatment by friction stirring, the base metal structure plastically flows vertically and horizontally by the pressing force and the rotation moment of the rotating tool. If the material is not pushed into the material at the shoulder portion, the material filled in the rotational direction of the tool is reduced, and tunnel-shaped unfilled defects are likely to occur inside the surface modification region along the movement trajectory.

The present invention has been made in view of the above problems, and an object thereof is to provide a rotary tool capable of increasing the action of pushing a base material structure that plastically flows by friction stirring into the inside of a material and preventing unfilled defects, and a rotary tool. It is an object of the present invention to provide a treatment method and a surface treatment method for a member used.

[0005]

In order to solve the above-mentioned problems and to achieve the object, a rotary tool of the present invention has a large-diameter shoulder portion that comes into contact with a work surface and a small-diameter shoulder portion that projects from the shoulder portion. A rotary tool that includes a protrusion, inserts a portion of the shoulder portion and the protrusion into the work surface while rotating, and agitates without melting the work surface due to frictional heat generated between the protrusion and the work. Then, a spiral groove for guiding the work material stirred by the frictional heat generated by the rotation of the tool to the central portion is formed on the end surface of the shoulder portion that comes into contact with the work surface, and the depth of the spiral groove is set to the protrusion portion. It formed shallower as it approached.

Further, preferably, a spiral groove is formed in the protrusion.

In the method for treating a member using a rotary tool according to the present invention, the shoulder is provided using a rotary tool having a large-diameter shoulder portion that comes into contact with the work surface and a small-diameter protrusion portion that protrudes from the shoulder portion. A method of treating a member that is inserted into a work surface while rotating a part of the portion and the protruding portion and that is agitated without melting the work surface by friction heat generated between the work and the shoulder portion. A spiral groove for guiding the work material stirred by the frictional heat generated by the rotation of the tool to the central portion is formed on the end surface in contact with the work surface, and the depth of the spiral groove is formed to be shallower as it approaches the protrusion. The rotating tool is moved in a state of being substantially vertical to the work surface.

The surface treatment method for parts using a rotary tool of the present invention uses a rotary tool having a large-diameter shoulder part that comes into contact with the surface of a workpiece and a small-diameter projection part that projects from the shoulder part. In a surface treatment method of a member which is inserted into a work surface while rotating a part of the shoulder portion and a protruding portion, and which is stirred and modified without melting the work surface by frictional heat generated between the work portion and the work. Then, on the end surface of the shoulder portion in contact with the work surface, a spiral groove for guiding the work material stirred by frictional heat due to the rotation of the tool to the central portion is formed, and the depth of the spiral groove is projected. The rotating tool formed so as to be shallower is moved toward the work surface with respect to the work surface.

Preferably, the rotary tool is reciprocally moved with respect to the work surface.

Further, preferably, the rotary tool reciprocates along paths offset from each other in a state substantially perpendicular to the work surface.

[0011]

As described above, according to the first aspect of the invention, the work material stirred by the frictional heat generated by the rotation of the tool is guided to the central portion of the end surface of the shoulder portion of the rotary tool that comes into contact with the work surface. By forming a spiral groove and making the depth of the spiral groove shallower as it gets closer to the protrusion, it is possible to increase the action of pushing the base metal structure that plastically flows by friction stirring into the material, and to prevent unfilled defects. It can be prevented.

According to the second aspect of the present invention, by forming the spiral groove in the protruding portion, it is possible to further increase the action of pushing the matrix material structure that plastically flows by friction stirring into the material.

According to the third and fourth aspects of the present invention, a spiral groove is formed on the end surface of the shoulder portion which comes into contact with the surface of the work, and which guides the work material stirred by the frictional heat generated by the rotation of the tool to the central portion. An action of pushing the base metal structure that plastically flows by friction stirring into the material by moving the rotary tool formed so that the depth of the spiral groove becomes shallower as it approaches the protrusion, in a state substantially vertical to the work surface. Can be increased and unfilled defects can be prevented.

According to the fifth aspect of the present invention, by reciprocating the rotary tool with respect to the surface of the work, it is possible to process a large area while preventing the occurrence of unfilled defects due to the direction change of the rotary tool.

According to the sixth aspect of the present invention, the rotary tool reciprocates along paths that are offset from each other in a state substantially perpendicular to the work surface, thereby preventing the occurrence of unfilled defects due to the direction change of the rotary tool. In addition, it is possible to process a large area.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

The embodiment described below describes an example in which the present invention is applied to a surface treatment as an example of a means for realizing the present invention. The present invention can be applied to modifications or variations of the following embodiments without departing from the spirit of the invention.

FIG. 1 is a schematic view of a friction stirrer for carrying out a surface treatment method according to an embodiment of the present invention. FIG. 2 is an enlarged view of the vicinity of the rotary tool of FIG. FIG. 3 is a detailed view of the tip portion of the rotary tool. FIG. 4 is a detailed view of the tip portion of the rotary tool as seen from the direction of arrow I in FIG. FIG. 5 is a II-II sectional view of FIG. FIG. 6 is a diagram showing the relationship between the depth of the spiral groove formed in the shoulder portion and the distance from the scroll start end portion in comparison with the conventional example.

The surface treatment by friction stirring of this embodiment is
Aluminum alloy castings are targeted as an example of surface-treated members (hereinafter referred to as "workpieces"). In particular, it is intended to improve the thermal fatigue strength between adjacent ports (valve portions), pistons, brake discs, etc. It is used for the intended surface modification treatment, and the surface modification area of aluminum alloy castings is stirred in the atmosphere without being melted by frictional heat, and the metal structure is refined and eutectic silicon (Si) particles are made uniform. We aim to disperse and reduce casting defects,
It is possible to obtain more than the conventional remelt treatment in terms of material properties such as thermal fatigue (low cycle fatigue) life, elongation and impact resistance.

Here, the state of stirring without melting means
This means that the metal is softened and agitated by frictional heat at a temperature lower than the lowest melting point among the components or eutectic compounds contained in the base material.

As shown in FIGS. 1 to 6, the friction stirrer 1 has a shoulder portion 3 in which a large-diameter end surface of one end of a cylindrical shaft is formed with a spiral groove 3a that swivels in a scroll shape.
A rotary tool 4 integrally formed with or attached with a non-consumable protrusion 2 having a spiral groove 2a formed on the outer peripheral surface having a diameter smaller than that of the shoulder portion 3, and the protrusion 2 is rotated by rotating the rotary tool 4. A tool driving unit 5 that inserts the protrusion 2 into the surface modification area of the work while rotating and drives the work surface relative to the shoulder 3 while pressing the work surface, and a jig that positions and holds the work ( (Not shown).

The tool driving means 5 is a device which can rotate the rotary tool 4 by a motor or the like and can move the rotary tool 4 in all directions of up, down, left and right by a feed screw mechanism, a robot arm or the like. 4, the number of revolutions, the feed rate, and the pressing force (processing depth) that can be variably controlled are used. As another form of the tool driving means 5, the rotary tool 4 is rotatably supported on the main spindle of an NC machine tool such as a machining center, and the work is relatively vertically moved by a movable table or the like with respect to the rotary tool 4. 2 left and right
It may be moved three-dimensionally or three-dimensionally.

The protrusion 2 and the shoulder portion 3 of the rotary tool 4 are made of a steel material such as tool steel or stainless steel having a hardness higher than that of an aluminum alloy, and the outer periphery of the protrusion 2 has a spiral groove 2a with a predetermined pitch. Are formed.

On the end face of the shoulder portion 3 which is in contact with the surface of the work, a spiral groove 3a is formed which presses the base material structure that plastically flows due to the frictional heat generated by the rotation of the tool into the material and guides it to the protrusion 2 in the central portion. As shown in FIG. 6, the spiral groove 3a is formed so that the depth of the spiral groove 3a becomes shallower as it approaches the base portion 3c of the protrusion 2 with the shoulder portion 3.

The spiral groove 3a extends from the scroll start end 3b at the outer edge of the shoulder portion 3 to the rotational direction R of the tool.
It is formed by 3/4 or more turns, preferably 1 or 2 turns so as to turn toward the base portion 3c of the protrusion 2 with the shoulder portion 3 in the opposite direction.

In this embodiment, as shown in FIG. 7, AC4D, which is an aluminum alloy standardized by JIS, is used as an example of the surface-treated member, but the magnesium (Mg) content of the aluminum alloy is 0.2. ~ 1.
The composition ratio can be changed within a range of 5% by weight and a silicon (Si) content rate of 1 to 24% by weight, preferably 4 to 13% by weight. Besides, AC4B, AC2B, AC8A used for the piston, and the like can also be used. Upper limit of silicon content is 2
The reason for setting it to 4% is that even if the amount of silicon is increased further, the material properties and castability are saturated, and the agitation property is deteriorated.

Aluminum alloy castings containing magnesium are heat treated to precipitate Mg ₂ Si, which increases the strength. However, when the metal structure is refined by melting it as in the remelting process, magnesium having a low melting point (650 ° C.) may evaporate and the content may decrease. When the magnesium content decreases, the hardness and strength decrease even if heat treatment is performed, and desired material properties cannot be obtained.

On the other hand, the surface treatment by friction stir, since magnesium does not melt the metal structure nor evaporates, Mg ₂ of the aluminum alloy casting heat treatment
The strength is increased by depositing Si.

By adding silicon to the aluminum alloy, the castability (fluidity of molten metal, shrinkage property, and heat cracking resistance) is improved, but eutectic silicon acts as a kind of defect and mechanical properties (elongation). ) Is reduced.

Eutectic silicon is hard and brittle, and serves as a starting point for crack initiation and a propagation path, so that elongation is reduced. In addition, the fatigue life of a portion such as an intervalve portion that is repeatedly subjected to thermal stress is reduced. The metal structure has a morphology of eutectic silicon that is continuous along the dendrites, but by reducing the size of the eutectic silicon and distributing it uniformly, cracks due to stress concentration and the propagation of cracks that occur are suppressed. It becomes possible to do. [Cylinder Head Manufacturing Method] Next, a manufacturing process of the diesel engine cylinder head according to the present embodiment will be described.

FIG. 8 is a flowchart for explaining the manufacturing process of the diesel engine cylinder head of this embodiment.

As shown in FIG. 8, in step S1, a cylinder head as an intermediate is cast from an aluminum alloy. In step S2, the casting is taken out of the casting mold and the gate is removed. In step S3, the cast product taken out from the casting mold is subjected to T6 heat treatment mainly for sand removal. In step S4, surface treatment is performed on the valve portion of the casting by friction stirring. In step S5, the casting is subjected to T6 heat treatment again to increase hardness and strength. In step S6, finishing is performed.

As described above, by performing the surface treatment by friction stirring, the conventional premelting pretreatment and casting preheating are unnecessary, so that the manufacturing process can be simplified and the manufacturing cost can be reduced as compared with the conventional method. You can [Surface Treatment by Friction Stirring] Next, step S4 in FIG.
The friction stir processing in step will be described.

A disadvantage of the surface treatment using the rotary tool 4 having the protrusion 2 as in this embodiment is that the end hole of the protrusion 2 remains at the end of the processing path. In order to solve this, when processing the surface of the casting where the drilling of bolts such as the cylinder head is performed in a later process, use a protrusion with a diameter smaller than the hole diameter in the drilling Set to the position where drilling is performed. This allows the product to have no end holes.

Further, a spiral groove 3a is formed on the end surface of the shoulder portion 3.
By forming the base material structure that plastically flows into the material while guiding it to the protrusion 2 in the central portion, the rotary tool 4 is vertically erected with respect to the surface of the work and the direction of the work is changed. It can be moved in a continuous reciprocating route without being removed.

FIG. 9 is a view for explaining the surface treatment of the cylinder head of the in-line multi-cylinder diesel engine using the friction stir treatment of this embodiment.

As shown in FIG. 9, the cylinder head material H
Is a pair of intake port openings 14 corresponding to a plurality of cylinders.
And a pair of exhaust port openings 15. here,
Since the intake port opening 14 is required to be as large as possible in order to earn the intake amount, the space between the adjacent intake ports becomes narrow and thin.

Therefore, in the present embodiment, as an example of the processing path, it passes between the intake port openings 14 facing each other with respect to one cylinder, and is followed by the exhaust port opening 15.
Between the exhaust port opening 15 and the forward path Q1 passing through the space between the exhaust port opening 15 and the forward path Q1 in a rectangular shape at the end of the exhaust port opening 15 in the opposite direction. The surface of the cylinder head material H is agitated and reformed without being melted by the heat of the rotary tool through the return path Q2 that continuously moves so as to pass through between 14.

As described above, by forming the spiral groove 3a on the end face of the shoulder portion 3, the movement including the continuous direction change from the forward path Q1 to the backward path Q2 is achieved.
The rotary tool 4 can be turned in a state in which the rotary tool 4 stands upright substantially vertically with respect to the surface of the work, and the treatment can be continuously performed without being pulled out from the surface of the work.

In the surface treatment by the reciprocating movement,
Since the work surface is scraped off by the shoulder portion 3 in the forward pass and lowered, the pushing amount of the rotary tool in the return pass after the direction is changed in the forward pass is set to be larger than the pushing amount in the forward pass.

In the surface treatment of the cylinder head, the rotational speed of the rotary tool is 600 to 1000 rpm, and the feed rate is 3.
00-500 mm / min, protrusion length 5.8 mm,
When the protrusion diameter is 7 ± 1 mm and the shoulder diameter is 15 ± 1 mm, the processing depth is 6 to 6.5 mm, the processing width of the first reciprocating path is 7.5 to 8 mm, and the processing width of the second reciprocating path is 15 mm. It is preferable to set as follows. The projection diameter and the shoulder diameter are set so that 2 ≦ shoulder portion / projection portion <4. Further, the pushing amount of the material of the shoulder portion with respect to the treated surface is set to 1 mm or less.

[Brief description of drawings]

FIG. 1 is a schematic view of a friction stirrer for carrying out a surface treatment method according to an embodiment of the present invention.

FIG. 2 is an enlarged view of the vicinity of the rotary tool of FIG.

FIG. 3 is a detailed view of a tip portion of the rotary tool.

FIG. 4 is a detailed view of the tip portion of the rotary tool as seen from the direction of arrow I in FIG.

5 is a sectional view taken along line II-II of FIG.

FIG. 6 is a diagram showing a relationship between a depth of a spiral groove formed in a shoulder portion and a distance from a scroll start end portion in comparison with a conventional example.

FIG. 7 is a diagram showing a component ratio of the aluminum alloy of this embodiment.

FIG. 8 is a flowchart illustrating a manufacturing process of a cylinder head for a diesel engine of this embodiment.

FIG. 9 is a diagram illustrating surface treatment of a cylinder head of an in-line multi-cylinder diesel engine using the friction stir treatment of the present embodiment.

[Explanation of symbols]

1 Friction stirrer 2 protrusion 3 shoulder section 4 rotating tools 5 Tool driving means 14 Intake port opening 15 Exhaust port opening H cylinder head material

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Seiji Nomura             3-1, Shinchi, Fuchu-cho, Aki-gun, Hiroshima Prefecture Mazda             Within the corporation (72) Inventor Koji Hori             1-34-1 Kambara, Kambara-cho, Anbara-gun, Shizuoka Prefecture             Nippon Light Metal Co., Ltd. Group Technology Center             Within (72) Inventor Shinya Makita             1-34-1 Kambara, Kambara-cho, Anbara-gun, Shizuoka Prefecture             Nippon Light Metal Co., Ltd. Group Technology Center             Within F-term (reference) 4E067 AA05 BG00 CA01 DC07 EA07                       EB00

Claims (6)

[Claims] 1. A shoulder part having a large diameter that comes into contact with the surface of the work, and a protrusion having a small diameter that projects from the shoulder part. The shoulder part and the protrusion are inserted into the work surface while rotating. A rotary tool that stirs the work surface without melting the work surface due to friction heat generated between the work and the end surface of the shoulder portion that comes into contact with the work surface, and the work is stirred by the friction heat due to the rotation of the tool. A rotary tool, characterized in that a spiral groove for guiding a material to a central portion is formed, and the depth of the spiral groove is formed so as to become shallower toward the protruding portion. 2. The rotary tool according to claim 1, wherein a spiral groove is formed in the protrusion. 3. A rotating tool including a large-diameter shoulder portion that comes into contact with a work surface and a small-diameter protrusion portion that protrudes from the shoulder portion while rotating a part of the shoulder portion and the protrusion portion. A method of treating a member which is inserted into a work surface and stirred without melting the work surface by frictional heat generated between the work and the end surface of the shoulder portion that comes into contact with the work surface. Forming a spiral groove that guides the work material stirred by the frictional heat to the center part, and the depth of the spiral groove is shallower as it approaches the protruding part A method for treating a member, characterized in that the member is moved by. 4. A rotating tool including a large-diameter shoulder portion that contacts a surface of a work and a small-diameter protrusion portion that protrudes from the shoulder portion while rotating a part of the shoulder portion and the protrusion portion. A surface treatment method of a member which is inserted into a work surface and is stirred and modified without melting the work surface due to frictional heat generated between the work surface and an end surface of the shoulder portion that comes into contact with the work surface. In addition, a spiral groove that guides the work material stirred by frictional heat due to the rotation of the tool to the central portion is formed, and the depth of the spiral groove becomes shallower as it approaches the protruding portion, with respect to the work surface. A surface treatment method for a member, characterized in that the surface treatment is carried out. 5. The surface treatment method for a member according to claim 3, wherein the rotary tool is reciprocally moved with respect to the surface of the work. 6. The surface treatment method for a member according to claim 4, wherein the rotary tool reciprocates along paths offset from each other in a state substantially vertical to the work surface.