JP2003048084A - Rotary tool and manufacturing method thereof, and treatment method using the rotary tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase friction stir welding effect while maintaining the effect of stirring a base metal structure in plastic flow and pressing it inside a work. SOLUTION: A coefficient of friction is increased by forming very fine unevenness through the shot-peening of a working surface of a tool after the machining and before the heat treatment in manufacturing a rotary tool.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary tool used for joining and surface treatment of aluminum alloy castings, a manufacturing method thereof, and a processing method 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 conventional rotary tool, a material made of tool steel or stainless steel is machined into a desired shape, and then heat treatment such as quenching / tempering, nitriding, and induction hardening is performed. Although it was manufactured by applying it, since it is inserted into the surface of the work while being rotated, the reduction of the tool life due to the rise of the work temperature is a problem.

The present invention has been made in view of the above problems, and an object thereof is to provide a rotating tool capable of increasing the friction stirring effect while maintaining the stirring of the plastically flowing base material structure and the pushing operation into the work, and a method for manufacturing the same. Another object of the present invention is to provide a processing method using the rotary tool.

In order to solve the above-mentioned problems and to achieve the object, a rotary tool of the present invention is provided with a frictional heat generated between a rotating work and a work, which is brought into contact with the work. Is a rotary tool that stirs a work without melting it, and forms a spiral groove at least in the contact portion of the rotary tool with the work, and forms a concavo-convex surface of 100 microns or more and 1/2 or less of the groove pitch. did.

Further, preferably, the uneven surface is formed by a shot peening step between machining and heat treatment which is carried out when the rotary tool is manufactured.

Further, preferably, the uneven surface is formed by a shot peening step after the machining and heat treatment performed at the time of manufacturing the rotary tool.

A method of manufacturing a rotary tool according to the present invention is a method of manufacturing a rotary tool in which a workpiece is rotated while being brought into contact with the workpiece and the workpiece is agitated without being melted by frictional heat generated between the workpiece and the workpiece. Forming a spiral groove at least in a contact portion of the rotary tool with respect to the work,
By shot peening, an uneven surface having a size of 100 microns or more and ½ or less of the groove pitch is formed.

The processing method using the rotary tool of the present invention is a processing using the rotary tool, in which the workpiece is rotated and brought into contact with the workpiece while being agitated without being melted by frictional heat generated between the workpiece and the workpiece. A method, wherein a spiral groove is formed at least in a contact portion of the rotary tool with respect to the work, and the spiral groove has a diameter of 100 μm or more and a groove pitch of 1 /
The processing area of the work is agitated by the rotating tool having the uneven surface of 2 or less.

[0009]

As described above, according to the first aspect of the present invention, the rotation is brought into contact with the work while rotating, and the work is agitated without being melted by the frictional heat generated between the work and the work. By forming a spiral groove on the tool at least in the contact portion of the rotary tool with the work and forming a concavo-convex surface of 100 microns or more and 1/2 or less of the groove pitch, stirring of the plastic material base material structure and work The friction stir effect can be increased while maintaining the action of pushing the inside.

According to the second aspect of the present invention, the uneven surface is formed by the shot peening process between the machining and the heat treatment performed during the manufacture of the rotary tool, so that the machined surface of the tool can be easily made uneven. Can be formed into

According to the third aspect of the present invention, the uneven surface is formed in the shot peening step after the machining and heat treatment performed when manufacturing the rotary tool, so that the uneven surface is formed on the machined surface of the tool. At the same time, compressive residual stress can be applied to the corners of the tool tip and the root of the protrusion and the shoulder.

According to the fourth aspect of the present invention, at least when the rotating tool is manufactured, the rotating tool is brought into contact with the workpiece while being rotated, and the workpiece is agitated without being melted by the frictional heat generated between the workpiece and the workpiece. By forming a spiral groove in the contacting part with the work and forming an uneven surface of 100 μm or more and ½ or less of the groove pitch by shot peening, stirring of the plastically flowing base metal structure and pushing into the work The friction stirring effect can be increased while maintaining the action.

According to the fifth aspect of the present invention, there is provided a processing method using a rotating tool, which is brought into contact with a work while rotating and agitates the work without melting the work due to frictional heat generated between the work and the work. A spiral groove is formed at least in the contact portion of the rotary tool with respect to the work, and the processing area of the work is agitated by the rotary tool having a concavo-convex surface of 100 μm or more and 1/2 or less of the groove pitch, whereby plastic flow is achieved. The friction stir effect can be increased while maintaining the stirring of the base material structure and the pushing into the work.

[0014]

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 embodiments described below are examples in which the present invention is applied to surface treatment as an example of the 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. 3 and 4 are detailed views of the tip portion of the rotary tool.

The surface treatment by friction stirring of this embodiment is
An aluminum alloy casting is used as an example of a surface-treated member (hereinafter referred to as a work), and particularly between adjacent port openings (valve portions) formed in a cylinder head of an automobile.
It is used for the surface modification treatment for the purpose of improving the thermal fatigue strength of pistons, pistons, brake discs, etc., and by stirring the surface modification area of aluminum alloy castings in the air without melting it by friction heat, Finer, more uniform dispersion of eutectic silicon (Si) particles, reduction of casting defects, and more than conventional remelt treatment in material properties such as thermal fatigue (low cycle fatigue) life, elongation and impact resistance. be able to.

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 3, in the friction stirrer 1, a spiral groove is formed on the outer peripheral surface having a diameter smaller than that of the shoulder portion 3 in the flat shoulder portion 3 at one end of the cylindrical shaft body. And a rotary tool 4 on which the non-consumable protrusion 2 is integrally formed or mounted, and the rotary tool 4 is rotated to drive the protrusion 2 while rotating the protrusion 2 with respect to the surface modification region of the workpiece.
And a tool (not shown) for positioning and holding the work.

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 any of up, down, left and right directions 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. [Shape of Rotating Tool] The protruding portion 2 and the shoulder portion 3 of the rotating tool 4 are made of steel material such as tool steel and stainless steel having a hardness higher than that of an aluminum alloy, and the outer periphery of the protruding portion 2 has a spiral with a predetermined pitch. The groove is formed.

Here, in the rotary tool 4 having the shoulder portion 3 and the protruding portion 2 shown in FIG. 3, the structure of the base material structure which is plastically flown by friction stirring is pushed into the work by the shoulder portion 3, so that the structure shown in FIG. As illustrated in the cross section of the surface-modified region, plastic flow occurs near the surface of the work over a range L2 that is considerably wider than the required processing width L1.
Further, if the processing width is wide, the side wall of the port opening is deformed when processing a narrow area such as between the port openings (valve area) of the cylinder head, and as shown in FIG. There is also an inconvenience that an excessive machining allowance is required for the shape, which causes an increase in material cost and machining cost.

Therefore, as shown in FIG. 6, in order to process a narrow portion of the work, a taper portion 42 having a diameter increasing from at least the end portion 41 of the rotary tool 40 inserted into the work toward the opposite work side is provided. It is preferable to form the spiral groove 43 in the tapered portion 42.

The spiral groove 43 is formed in a direction in which the base material structure frictionally stirred with respect to the rotating direction of the tool is pushed into the work.

According to the rotary tool 40, the tapered portion 42
The matrix material that plastically flows is pushed in by the spiral groove 43 of
Since the shoulder portion does not cause plastic flow in the vicinity of the work surface, the processing width L can be narrowed as illustrated in the surface modification region cross section in FIG. 7, and the intervalve portion after the finish machining as shown in FIG. The minimum machining allowance for the shape is sufficient. [Rotary tool manufacturing method] Conventional rotary tools are produced by machining a material made of tool steel or stainless steel into a desired shape by machining, and then subjecting it to heat treatment such as quenching / tempering, nitriding, and induction hardening. Although it was manufactured, it is a problem that the tool life is shortened due to the rise of the work temperature because it is inserted while rotating on the work surface.

Therefore, in the present embodiment, after the machining during the rotary tool production and before or after the heat treatment, fine irregularities are formed by shot peening on the machined surface of the tool to increase the friction coefficient. The rotary tool can be applied to the shape having the protruding portion 2 and the shoulder portion 3 shown in FIG. 5 or the shape having the tapered portion 42 shown in FIG.

When shot peening is performed on the rotary tool shown in FIG. 9 after machining and before heat treatment, the tool material is not hardened before heat treatment, so that it is easy to form irregularities on the machined surface of the tool. Become.

The size of the shot is preferably 1/2 or less of the groove pitch so that irregularities can be formed on the surfaces of the spiral grooves 2a and 43 of the rotary tools 4 and 40.

If the size of the shot is small, the effect of increasing the coefficient of friction due to the formation of irregularities is reduced, so that 100
μm or more is desirable.

In shot peening before heat treatment,
Unevenness is formed on the entire spiral groove of the rotary tool using a small shot, and after heat treatment, bending peening is performed again using shot peening on the tool tip corner and the root of the protrusion 2 and the shoulder 3 using a large shot. A compressive residual stress with respect to may be applied.

When the rotary tool shown in FIG. 10 is subjected to shot peening after machining and after heat treatment, the irregularities are formed on the machined surface of the tool, and at the same time, at the tip of the tool and at the base of the protrusion and the shoulder. Since compressive residual stress can be applied, it is effective in extending the tool life.

The size of the shot is preferably 1/2 or less of the groove pitch so that the surface of the spiral grooves 2a and 43 of the rotary tools 4 and 40 can be uneven.

If the size of the shot is small, the effect of increasing the coefficient of friction due to the formation of irregularities is reduced, so that 100
μm or more is desirable. The hardness of the shot is equal to or higher than the tool hardness after heat treatment. [Workpiece Application Example] In this embodiment, as shown in FIG. 11, 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 used as an example. 0.
2 to 1.5% by weight, as a silicon (Si) content rate 1 to
The composition ratio can be changed within the range of 24% by weight, preferably 4 to 13% by weight. Besides, AC4B, AC2B, AC8A used for the piston, and the like can also be used. The reason for setting the upper limit of the silicon content rate to 24% is that even if the silicon content is increased further, the material properties and the castability are saturated, and the agitation property is deteriorated.

The aluminum alloy casting containing magnesium is heat-treated to precipitate Mg ₂ Si, so that the strength is increased. 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 crack 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 of 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. 12 is a flow chart for explaining the manufacturing process of the cylinder head for a diesel engine of this embodiment.

As shown in FIG. 12, 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, pre-processing for smoothing the rough casting surface of the casting is performed. In step S5, surface treatment is performed on the valve portion of the casting by friction stirring. In step S6, the casting is subjected to T6 heat treatment again to increase hardness and strength. In step S7, finishing is performed according to the finishing dimension. [Surface Treatment in Hot Water] Conventional friction stir processing is performed in the atmosphere, and the initial temperature of the work is room temperature.
Then, in order to quickly raise the temperature of the work to a temperature at which friction stirring can be performed and reduce the load on the tool due to the temperature rise, the work is preheated in the preheating furnace and then processed. However, there are cases where the preheating furnace cannot be installed due to space problems.

Therefore, in this embodiment, FIG. 13 and FIG.
As shown in FIG. 4, a predetermined temperature (50 to 10
Surface treatment by friction stirring is performed with only the work H or the work H and the rotary tool 4 immersed in a medium 12 such as warm water maintained at 0 ° C.).

When the work surface of FIG. 13 is immersed in warm water for treatment, the work H can be preheated by heat transfer from the warm water 12 and the work temperature can be kept constant, so that the occurrence of residual stress is suppressed as much as possible. On the other hand, when preheated in the preheating furnace, the temperature of the work taken out from the furnace gradually decreases, the temperature difference between the parts of the work increases, and residual stress easily occurs. In addition, since the preheating furnace is not required, it is possible to save space.

When the work surface in FIG. 14 is processed without being submerged in warm water, the work H can be preheated by heat transfer from the warm water 12 and the work temperature can be kept constant, so that the occurrence of residual stress is suppressed as much as possible. On the other hand, when preheated in the preheating furnace, the temperature of the work taken out from the furnace gradually decreases, the temperature difference between the parts of the work increases, and residual stress easily occurs.

Further, since the preheating furnace is not required, it is possible to save space, and particularly when hot water is used, the post-cleaning of the work is not required, so that the working process can be simplified.

Further, since the treated area on the surface of the work is not immersed in hot water, the surface is not cooled, so that the temperature difference of the whole work is reduced and the occurrence of residual stress is suppressed without suppressing the rise of the work temperature. be able to.

The surface treatment in the hot water is performed by immersing the work H in the hot water 12 and rotating the work H in the hot water 12 with a work transfer device as a work inserting means for positioning and holding the work H on a jig or the like. This is performed by a machining center or the like as the tool driving means 5 that stirs and modifies the work surface with a tool. [Workpiece supporting method] In the case of surface treatment by friction stirring, since the shoulder portion 3 of the rotary tool 4 is moved while being pressed against the workpiece surface, burrs are generated on the workpiece surface corresponding to the outer peripheral edge portion of the shoulder portion 3. It is necessary to perform a burr removal process to remove this burr.

However, as shown in FIG. 15, if the removed burrs are dropped and remain on the jig 9 for holding the work H or the movable table 10, the work H and the jig 9 or the like will be left when the next work is set. Burrs are caught between the movable table 10 and accurate positioning cannot be performed, and the processing depth may change to cause unfilled defects, or the work may be stopped due to an abnormal setting of the work.

Therefore, in the present embodiment, the work H is jig 9 with the taper pin 8 or the stepped pin which is provided so as to project vertically upward from the jig 9 shown in FIG.
Position and hold it in a state of floating from above. In the case of a stepped pin, a burr may remain on the step portion, so a configuration using a tapered pin is preferable.

As another method of supporting the work, FIG.
As shown in FIG. 7, the work H is held so that the work surface is directed to the side so that the work H is not lifted from the movable table 10 and the burr does not fall downward to affect the holding posture of the work H. As shown in FIG. 18, the work surface may be held vertically downward, and the work H may be held so that the burr does not drop and does not affect the holding posture of the work H.

Further, as the rotary tool 4 advances, the work surface is scraped at the tip of the shoulder portion 3, so that the amount of burrs generated increases. Therefore, as a method of reducing burrs themselves generated during the surface treatment, FIG. As shown in FIG. 19, the outer peripheral edge portion of the shoulder portion 3 may be chamfered or curved, and the chamfered portion 3d of the shoulder portion 3 may crush the work surface as the rotary tool 4 advances. This chamfer 3
It is preferable that d is larger than the pressing amount of the shoulder portion 3 with respect to the work surface. [Surface Treatment Method] The surface treatment by friction stirring is performed after pre-processing such as milling for smoothing the surface of the as-cast work (see FIG. 12).
Since the rotary tool scrapes the work at the tip of the shoulder as it advances along the processing path with respect to the work surface, if the work surface is rough, the amount of burrs increases, and This increases the burden and shortens the work life. The load on the shoulder portion is further increased when the surface of the as-cast work is directly processed or when the work is processed without preheating.

Further, in the case of directly processing an as-cast work, since the casting surface is rough, the amount of indentation of the rotary tool with respect to the work surface changes substantially, and unfilled defects easily occur inside the work. Become.

Therefore, in this embodiment, as shown in FIG. 20, a preheating rotation having only a shoulder portion 3 having a flat tip end without a protrusion 2 is provided for a pre-worked work H1 having a smooth casting surface. The friction stirrer rotary tool 4B including the shoulder portion 3 and the protrusion 2 to be inserted into the workpiece surface is moved so as to move the tool 4A in advance while being in contact with the workpiece surface and follow the preheater rotary tool 4A. Move it while inserting it into the surface.

In this structure, since the work surface can be preheated by the preheating rotary tool 4A before friction stirring, it is possible to prevent unfilled defects and prevent damage to the rotary tool (particularly the protrusion).

Further, as shown in FIG. 21, a preheating rotary tool 4A having only a shoulder portion 3 having a flat tip end without a protrusion 2 is attached to the work surface of the work H2 in the as-cast condition where the casting surface has not been treated. A friction stirrer rotary tool 4 having a shoulder portion 3 and a protrusion 2 to be inserted into the work surface so as to follow the preheater rotary tool 4A while being moved in advance while scraping.
B is moved while being inserted into the surface of the work.

With this construction, pre-processing is not required, and the cost can be reduced, and at the same time, the surface of the work can be preheated by the preheating rotary tool 4A before the frictional stirring while smoothing the casting surface, thus preventing unfilled defects. And rotary tools (especially protruding parts)
Can be prevented from being damaged.

The preheating and friction stirrer rotary tool 4 is used.
The surface treatment using A and 4B is performed by relatively moving each of the rotary tools 4A and 4B or the works H1 and H2, but the rotary tools 4A and 4B are used as the first and second tool driving means for a spindle such as a machining center. The workpieces positioned and held by the jig are moved relative to each other by a movable table or the like, so that processing can be continuously performed even in a processing path that requires a direction change.

Further, in the preheating rotary tool 4A, a recess may be formed on the end surface of the shoulder portion 3 in order to further improve the friction stirrability in the preheating stage. Further, as the preheating rotary tool 4A and / or the friction stirrer rotary tool 4B, the rotary tool 40 having the tapered portion 42 shown in FIG. 6 may be applied. [Movement trajectory of rotating tool] In surface treatment by friction stirring,
Although the terminal hole to which the shape of the protruding portion is transferred remains at the processing end portion, the terminal hole can be prevented from remaining if the portion to be subjected to the drilling process in the subsequent step is set as the terminal hole position. On the other hand, depending on the size of the processing area of the workpiece, it is necessary to reciprocate the processing paths of the rotary tool while offsetting each other to process the same portion twice or more.

Further, since the protrusion of the rotary tool is pushed into the work surface at the start of the surface treatment, as the number of times of pushing increases, a large load is repeatedly applied to the shoulder portion of the tool and the root of the protrusion to break the protrusion. The tool life is shortened, and unfilled defects are likely to occur near the portion where the tool is pushed.

Therefore, in this embodiment, the movement locus of the work associated with the surface treatment is set to a continuous one-stroke writing mode, and the number of times the rotary tool is pushed into the work surface per work is greatly reduced to one, thereby shortening the tool life. I was able to extend it.

22 and 23 are views 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. 22, the cylinder head material H includes a pair of intake port openings 1 corresponding to a plurality of cylinders.
4, a pair of exhaust port openings 15, and a plurality of tension bolt holes 2 for fastening to a cylinder block (not shown).
1 and. Here, since there is a demand for making the intake port opening 14 as large as possible in order to make the intake amount large, the space between adjacent intake ports becomes narrow.

In the present embodiment, as an example of the first processing path shown in FIG. 22, one end of the cylinder head material H is used as a starting point S to push the protrusion of the rotary tool onto the work surface, and from this starting point, the length of the cylinder head material H is increased. Toward the other end in the direction, so that the tension bolt hole 21 becomes an end point by continuously processing so as to pass between a pair of the exhaust port opening 15 and the intake port opening 14 that face each other for one cylinder. The processing route Q is set.

Specifically, with respect to the portion corresponding to the cylinder closest to the starting point S, the pair of intake port openings 14 are moved in the longitudinal direction toward the other end of the cylinder head material H. After that, the cylinder head material H is bent in the width direction and a pair of intake port opening 14 and exhaust port opening 15 are formed.
Between the centers of the pair of exhaust port openings 15 in the longitudinal direction toward the other end of the cylinder head material H, and then reciprocating. To move. Then, without removing the rotary tool from the surface of the work, the rotary tool is continuously moved in the same path with respect to the adjacent cylinders, and the tension bolt hole 21 formed at the other end of the cylinder head material H is set as the end point. To do.

Further, as a second processing path example shown in FIG. 23, the length of the cylinder head material H is set so as to pass between a pair of the exhaust port opening 15 and the intake port opening 14 facing each other for one cylinder. Direction outward from one end in the direction to the other end, and the first outward pass Q1 that ends in the tension bolt hole 21 and the other end of the cylinder head material H turns to a rectangular shape to form the first outward pass. The cylinder head material H is continuously processed from the other end to the one end in the longitudinal direction so as to pass in parallel between the pair of the exhaust port opening 15 and the intake port opening 14 offset in the direction opposite to Q1. The first return pass Q2 with the tension bolt hole 21 as the end point, and the first return pass Q2 after the first return pass Q2 is processed.
A pair of exhaust ports 15 and a pair of intake ports 1 facing each other from the cylinder adjacent to the direction change position to the return path Q2.
4 through the second reciprocating path Q3 to Q6 with the tension bolt hole 21 as the end point, the surface of the cylinder head material H is agitated without being melted by the heat of the rotary tool. To quality.

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,
With a projection diameter of 7 ± 1 mm and a shoulder diameter of 15 ± 1 mm, the processing depth is 6 to 6.5 mm, the processing width of the first pass is 7.5 to 8 mm, and the processing width of the second pass is 15 mm. It is preferable to set.

The projection diameter and the shoulder diameter are set so that 2 ≦ shoulder portion / projection <4. Also,
The indentation amount of the material of the shoulder part to the treated surface is 1
Set to mm or less. Furthermore, the rotary tool may have its axis centered about 1 ° with respect to the surface of the work, as opposed to the direction of travel of the tool. [Prevention of Deformation of Intervalve Portion] As described above, in the intervalve portion of the cylinder head material H, due to the difference in work rigidity due to the difference in cross-sectional shape of the port opening, the base material structure due to the pushing of the rotary tool 4 The vertical plastic deformation and horizontal plastic deformation due to the rotation moment are likely to occur, so in the past, considering the deformation of the port opening, an extra machining allowance to be deleted in the finishing process was taken into consideration. ing.

Further, when the intervalve portion is processed twice by the reciprocating path, the frictional heat due to the first forward processing is conducted in the second return processing area, so that the Young's modulus is lowered and the deformation occurs as the temperature rises. If the amount of deformation is excessive, the flow of the base material structure is promoted in the deformed direction, so that the base material structure filled on the side opposite to the deformed direction is reduced and the movement trajectory Q is formed inside the processing area. Tunnel-like unfilled defects are likely to occur along the line.

Therefore, in this embodiment, FIG. 24 and FIG.
5, the intake and exhaust port openings 14, 15
Insert the taper movable pin 17 that can be inserted into and removed from the port and becomes thinner toward the distal end into the port openings 14 and 15,
It is configured to suppress the deformation of the side wall of the.

The taper movable pin 17 has a taper shape that becomes thinner toward the tip end, and is devised so that it can be easily removed from the port opening.

Since the movable mechanism of the taper movable pin 17 is provided at a position near the tool driving means 5 of the rotary tool, it becomes a complicated mechanism. Therefore, as shown in FIG. 26 and FIG. 27, the cover member 18 having the taper pin protruding corresponding to the port opening position of the work is configured to separate the movable mechanism from the tool driving means 5 of the rotary tool. It can also be a simple mechanism.

Further, as shown in FIGS. 28 and 29, when the work is cast out from the mold, the port opening 14,
By performing the surface treatment with the sand core 19 for forming 15 left, it is possible to suppress the deformation of the side wall portion of the intervalve portion 16.

However, in the state where the sand core 19 is left, the sand may scatter during the surface treatment and the sand may be mixed into the inside of the treatment area. Therefore, the port openings 14 and 1 shown in FIGS.
Alternatively, the sand core 19 left on the cover 5 may be treated while being covered with the cover member 20 which is detachably attached to the port openings 14 and 15 by the movable mechanism. [Inspection method for defects of surface treatment member] Defects generated in the treatment area due to friction stirring are generally detected by visual observation by humans, but since destruction (cutting) inspection by sampling is the main, it is possible to inspect all of them. It is impossible, and if the size of the defect becomes small, it becomes difficult to detect it visually. Also,
In the case of the surface treatment by friction stirring as in the present embodiment, burrs are generated on the surface of the work, so that it becomes more difficult to visually detect defects in the portion covered with burrs.

Therefore, in the present embodiment, the position of the processing region is confirmed based on the difference in conductivity between the unprocessed tissue and the processed tissue, and the internal unfilled defect of the work is detected by ultrasonic inspection.

As shown in FIGS. 32 and 33, the conductivity of the treated region by friction stirring is higher than that of other untreated tissues. Therefore, by utilizing this characteristic, a conductivity sensor or the like is brought into contact with the surface of the work. While automatically moving to the periphery of the processing area, the conductivity of the workpiece around the processing area is detected.

Then, the region where the conductivity exceeds the predetermined threshold value is regarded as the processing region, and the region where the conductivity exceeds the predetermined threshold value and the inspection region are determined by comparing the region with the actual inspection of the work. If they match, the processing area is at an appropriate position, and if they do not match, it is determined that the processing area is displaced.

The threshold value of the electric conductivity is 38.5% IACS for the cylinder head made of aluminum alloy casting from FIG.
It is set to a degree.

The presence or absence of the internal unfilled defect of the workpiece and the processing position can be detected by ultrasonic inspection, and the processing depth can be confirmed by inspection of the processing region because it is determined by the pushing amount of the rotary tool.

The shape and manufacturing method of the rotary tool, the surface treatment in warm water, the method of supporting the work, the surface treatment method, the movement trajectory of the rotary tool, which are described item by item as the above embodiment,
The deformation prevention of the intervalve portion and the defect inspection method of the surface treatment member can be carried out by arbitrarily combining the respective methods.
A rotary tool 4 in which a spiral groove 43 is formed in the tapered portion 42 shown in FIG.
No. 0, the movable cover member is provided with the taper pin 8 shown in FIG. 16 in the warm water 12 shown in FIG. 18 for intake and exhaust port opening 1
It is a preferable mode to insert into Nos. 4 and 15 and preheat the workpiece along the processing path Q of the one-stroke writing mode shown in FIG. 22 with one rotary tool. Then, the processing area may be inspected by the conductivity and the internal unfilled defect may be inspected by ultrasonic waves.

[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 shape of a rotary tool having a protrusion and a shoulder.

FIG. 4 is a cross-sectional view of a surface modification region by a rotary tool having the tip shape of FIG.

5A and 5B are diagrams showing a comparison between valve-valve shapes before and after finishing using a rotary tool having a tip shape shown in FIG.

FIG. 6 is a detailed view of a tip shape of a rotary tool having a tapered portion 42.

FIG. 7 is a cross-sectional view of a surface modification region by a rotary tool having the tip shape of FIG.

FIG. 8 is a view showing a comparison between intervalve shapes before and after finishing using the rotary tool having the tip shape shown in FIG. 6;

FIG. 9 is a diagram illustrating a manufacturing process of a tool when shot peening is performed on a rotary tool after machining and before heat treatment.

FIG. 10 is a diagram illustrating a manufacturing process of a tool when shot peening is performed on a rotary tool after machining and after heat treatment.

FIG. 11 is a diagram showing a component ratio of the aluminum alloy of this embodiment.

FIG. 12 is a flowchart illustrating a manufacturing process of a cylinder head for a diesel engine of this embodiment.

FIG. 13 is a diagram illustrating a surface treatment method when a work surface is submerged in warm water for treatment.

FIG. 14 is a diagram illustrating a surface treatment method in the case of treating a work surface without submerging it in warm water.

FIG. 15 is a view showing a state in which a burr is sandwiched by a conventional work supporting method.

FIG. 16 is a diagram showing a method of supporting a work according to the present embodiment.

FIG. 17 is a diagram showing a method of supporting a work according to another embodiment.

FIG. 18 is a view showing a method for supporting a work according to another embodiment.

FIG. 19 is a view showing a surface treatment method using a rotary tool which chamfers the shoulder portion and suppresses the occurrence of burrs.

FIG. 20 is a diagram showing a surface treatment method using a preheating rotary tool and a friction stirring rotary tool after pre-processing for smoothing a work surface.

FIG. 21 is a diagram showing a surface treatment method using a rotary tool for preheating and a rotary tool for friction stirring that smoothes the surface of a work.

FIG. 22 is a diagram showing an example of a treatment route in the surface treatment of the present embodiment.

FIG. 23 is a diagram showing another example of a processing route in the surface treatment of this embodiment.

FIG. 24 is a diagram showing a state in which a tapered movable pin is inserted into a port opening to prevent deformation of an intervalve portion of a cylinder head when the surface treatment of the present embodiment is performed.

25 is a cross-sectional view taken along the line I-I of FIG. 24.

FIG. 26 is a view showing a state in which a cover member having a taper pin projecting from the port opening is inserted in order to prevent deformation of the valve-valve portion of the cylinder head when performing the surface treatment of the present embodiment.

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

FIG. 28 is a diagram showing a state in which a sand core is left in the port opening portion to prevent deformation of the valve portion of the cylinder head when the surface treatment of the present embodiment is performed.

29 is a sectional view taken along the line III-III in FIG. 28.

FIG. 30 is a view showing a state in which a cover member is attached while leaving a sand core in a port opening in order to prevent deformation of an intervalve portion of a cylinder head when performing a surface treatment of the present embodiment.

31 is a cross-sectional view taken along the line IV-IV of FIG. 30.

FIG. 32 is a diagram showing a change in conductivity when the processing region of the intervalve portion is located at an appropriate position.

FIG. 33 is a diagram showing a change in conductivity when a processing region is displaced from an appropriate position.

FIG. 34 is a diagram showing a comparison between the electric conductivity of the material subjected to the surface treatment by friction stirring and the base material of the present embodiment.

[Explanation of symbols]

1 Friction stirrer 2 protrusion 3 shoulder section 4,40 rotary tool 5 Tool driving means 14 Intake port opening 15 Exhaust port opening 16 valve area H work (cylinder head material)

Claims (5)

[Claims] 1. A workpiece is rotated and brought into contact with the workpiece,
A rotary tool for stirring a work without melting the work by frictional heat generated between the work and the work, wherein a spiral groove is formed at least in a contact portion of the rotary tool with the work, and the groove pitch is 100 μm or more and a groove pitch. A rotating tool having an uneven surface of ½ or less of the above. 2. The rotary tool according to claim 1, wherein the uneven surface is formed by a shot peening process between machining and heat treatment performed when manufacturing the rotary tool. 3. The uneven surface is formed by a shot peening process after machining and heat treatment performed when manufacturing the rotary tool.
The rotating tool described in. 4. A workpiece is rotated and brought into contact with the workpiece,
A method for manufacturing a rotating tool, wherein the rotating tool is agitated without being melted by frictional heat generated between the workpiece and the workpiece, wherein a spiral groove is formed at least in a contact portion of the rotating tool with the workpiece. A method for manufacturing a rotary tool, comprising forming an uneven surface having a diameter of not less than micron and not more than 1/2 of a groove pitch. 5. A workpiece is rotated and brought into contact with the workpiece,
A processing method using a rotating tool, which stirs a workpiece without melting it by frictional heat generated between the workpiece and the workpiece, wherein a spiral groove is formed at least in a contact portion of the rotating tool with the workpiece, The processing method is characterized in that the processing area of the work is agitated by the rotating tool having the uneven surface having a groove pitch of ½ or less of the groove pitch.