JP2001246458A - Surface treating method and treating member therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To deepen a treating range while preventing unfilling defect caused by the deformation of a base stock. SOLUTION: The surface of a cylinder head H is modified by stirring without melting with the heat of a rotating tool through a first pass P1 which is continuously treated from the one end part toward the other end part of a tension bolt hole 21 as the end point in the longitudinal direction of the cylinder head H so as to pass through the intervals among respective pairs of exhaust ports 15 and intake ports 14 mutually faced to one cylinder, and through second passes P2-P5 which are treated in order among pairs of the exhaust parts 15 and the intake parts 14 mutually faced from the cylinder adjoined to the end point of this first pass P1 after treating this first pass P1 to the respective tension bolt holes 21 as the end points.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art In recent years, the maximum compression pressure in a combustion chamber has been increased to 120 kgf with an increase in the output of a diesel engine of an automobile.
/ Cm ^{2 to} about 150 kgf / cm ^2, increasing the heat load on aluminum alloy castings such as cylinder heads that constitute the combustion chamber, and locally increasing the heat resistance to thermal fatigue and thermal stress. A remelt process is performed (for example, between adjacent ports (intervals)) (see FIG. 30). Also, the required remelt depth is larger than in the past.

FIG. 34 is a flow chart for explaining a manufacturing process of a conventional cylinder head for a diesel engine. FIG. 35 is a view for explaining the outline of the remelt process in the manufacturing process of FIG.

[0004] As shown in FIG. 34, in step T1, a cylinder head as an intermediate is cast. Step T2
Then remove it from the mold and remove the gate. Step T3
Then, the casting is subjected to a T6 heat treatment mainly for sand removal.
In step T4, pre-remelting processing is performed. In Step T5, the casting is preheated. In Step T6, a remelt process is performed on the inter-valve portion of the casting. In Step T7, the casting is subjected to T6 heat treatment again. In step T8, a finishing process is performed.

[0005] In the remelt treatment, as shown in FIG. 35, a sand casting is preheated, an electrode is brought close to a surface-treated region, and a TIG or plasma arc is generated between the electrode and the surface-treated member. By moving and melting the structure to be processed at a predetermined depth and solidifying it again, the metal structure is refined, and casting defects are reduced and elongation is increased. Furthermore, the residual stress due to the remelting process is released by performing the T6 heat treatment again after the remelting process. In the remelt treatment, the metal structure is refined by increasing the cooling rate during resolidification.

Another surface treatment method is disclosed in Japanese Patent Laid-Open No. 7-88.
No. 645 discloses that in the inter-valve portion, the A having a higher solidus than the base metal is used.
A structure is disclosed in which a high-strength layer is formed by overlay welding of an l-Cu-based alloy to improve bondability with a base material and improve thermal fatigue resistance.

[0007] Further, although this is a technical field different from the surface treatment technology, Japanese Patent No. 2712838 discloses that a probe is inserted and translated while rotating a joint surface of two members, and the metal structure near the joint surface is rubbed. A welding technique of plasticizing and bonding by heat is disclosed.

Japanese Patent Application Laid-Open Nos. Hei 10-183316 and 2000-15426 disclose a rotary tool provided with a protruding portion at a shoulder portion at a tip in a surface treatment of a casting such as a mating surface of a cylinder head with a cylinder block. A surface treatment method is disclosed in which the material is rotated while being pushed in, and is stirred in a non-molten state by heat.

[0009]

However, in the above remelting process, since the heat capacity of the inter-valve portion is small, the amount of heat input is increased in order to increase the processing depth in order to cope with an increase in the thermal load on the cylinder head. Even so, shoulder melting occurs due to over-melting, and there is a limit to the processable depth.
In addition, when the heat input is increased, the solidification time of the treated part is prolonged, and the effect of the refinement of the structure is reduced, and the number of pinhole defects is also increased. It is difficult to obtain improvement effects.

[0010] Further, if the heat input amount is increased, the member is likely to crack due to thermal stress during the remelting process.
Preheating of components is required. In addition, in the base material containing magnesium, magnesium evaporates and decreases during melting,
The T6 heat treatment after the remelt treatment may reduce the strength improvement margin, and may not provide the required mechanical properties.

In terms of quality, large variations in processing depth due to variations in the amount of heat input and misalignment due to magnetic blowing, etc., and pinhole defects in the processed part affect the gas content of the base material and the area ratio of the voids. Ensuring quality stability has become an issue due to the quality of the product.

In terms of productivity, since the processing section is melted, a shield gas for preventing oxidation of the molten portion is required. In addition, in order to prevent defects due to gas generated from surface oxides and impurities, A step of removing the casting surface before the treatment is added. Furthermore, cost reduction is an issue because post-heat treatment is required to release high tensile residual stress generated in the processing section.

Further, in the overlay welding described in the above-mentioned publication, the method of supplying the overlay member is problematic in terms of productivity, and in terms of quality, there is a problem of suppressing pinhole defects and ensuring stability of the base material dilution ratio. In addition, the problem caused by melting the base material has the same problem as the remelt treatment.

On the other hand, in the techniques described in JP-A-10-183316 and JP-A-2000-15426, in order to prevent a material from being deformed and to process a wide area with a small protrusion, a processing path and the like are required. It must be set appropriately.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a surface treatment method and a treatment member capable of deepening a treatment region while preventing unfilled defects due to deformation of a material.

[0016]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems and to achieve the object, a surface treatment method of the present invention comprises stirring a surface of a casting having a recess without melting it by the heat of a rotary tool. A surface treatment method for modifying the surface of the rotary tool in a region closest to the recess, wherein a flow of a material between the recess and the rotary tool is in a traveling direction of the rotary tool. On the other hand, a surface treatment is performed so as to be in the opposite direction.

Further, the surface treatment method of the present invention is a surface treatment method in which the surface of a casting having a recess is modified by stirring without melting the surface of the casting by the heat of a rotary tool. The surface treatment is performed so that the surface treatment path of the rotary tool in the region is such that the flow of the material between the recess and the rotary tool is in the same direction as the traveling direction of the rotary tool.

Further, the surface treatment method of the present invention is a surface treatment method in which the surface of a casting to be drilled is agitated without being melted by the heat of a rotary tool to modify the surface. Using a rotary tool having a diameter smaller than the diameter, surface treatment is performed such that the end point of the surface treatment path by the rotary tool is a position where the drilling is performed.

[0019] Preferably, the semiconductor device further includes a plurality of the recesses, and the space between the recesses is modified by the rotating tool.
The surface treatment path is set so that the modified regions overlap.

Preferably, an end point of the surface treatment path is set so as to pass through a start point of the surface treatment path.

[0021] Preferably, the casting is a cylinder head having a pair of intake ports and a pair of exhaust ports corresponding to a plurality of cylinders, and passes between the pair of exhaust ports and the pair of intake ports. After the continuous processing in the longitudinal direction of the cylinder head as described above, the surface processing is performed so as to pass between the pair of the exhaust port and the intake port from the cylinder adjacent to the position.

Further, the surface treatment member of the present invention has a recess, and the surface is agitated without being melted by the heat of the rotary tool, and the surface is agitated and modified. The surface treatment is performed so that the surface treatment path of the rotary tool in the region is such that the flow of the material between the recess and the rotary tool is in the opposite direction to the traveling direction of the rotary tool.

Further, the surface treatment member of the present invention has a recess, and the surface is agitated without being melted by the heat of the rotary tool, and the surface is agitated and modified. The surface treatment is performed so that the surface treatment path of the rotary tool in the region is such that the flow of the material between the recess and the rotary tool is in the same direction as the traveling direction of the rotary tool.

Further, the surface treatment member of the present invention is a treatment member which is subjected to drilling, and the surface of which is agitated and reformed without being melted by the heat of the rotary tool. The surface treatment is performed using a small-diameter rotary tool so that the end point of the surface treatment path by the rotary tool is a position where the drilling is performed.

[0025]

As described above, according to the invention of claim 1 or 7, when the surface of a casting having a recess is reformed by stirring without melting by the heat of a rotary tool, The surface treatment path of the rotating tool in the closest area of
By applying a surface treatment so that the flow of the material between the recess and the rotating tool is in the opposite direction to the traveling direction of the rotating tool, the unfilled defect due to deformation of the material is prevented, and the processing area is reduced. Can be deepened.

According to the second or eighth aspect of the present invention, when the surface of a casting having a recess is reformed by stirring without melting the surface of the casting by the heat of the rotating tool, the rotary tool in a region closest to the recess is used. The surface treatment path is subjected to surface treatment so that the flow of the material between the recess and the rotating tool is in the same direction as the traveling direction of the rotating tool. The processing area can be widened while preventing shoulder dripping at the edge.

According to the third or ninth aspect of the present invention, when the surface of the casting to be drilled is reformed by stirring without being melted by the heat of the rotary tool, the diameter of the hole is smaller than the diameter of the hole in the drilling. By performing surface treatment using a rotary tool such that the end point of the surface treatment path by the rotary tool is a position where drilling is performed, the product can be finished without leaving a terminal hole.

According to the fourth aspect of the present invention, a plurality of recesses are provided, the space between the recesses is reformed by the rotary tool, and the surface treatment path is set so that the reformed areas overlap. In addition, the processing area can be widened and deepened while preventing unfilled defects due to deformation of the material.

According to the fifth aspect of the invention, by setting the end point of the surface treatment path so as to pass through the start point of the surface treatment path, it is possible to finish the product without leaving an end hole.

According to the sixth aspect of the present invention, the casting is a cylinder head having a pair of intake ports and a pair of exhaust ports corresponding to a plurality of cylinders, and is provided between the pair of exhaust ports and the pair of intake ports. After continuous processing in the longitudinal direction of the cylinder head so as to pass through, the cylinder end adjacent to the position is subjected to surface treatment so as to pass between the pair of the exhaust port and the intake port, so that the port end of the cylinder head The processing region can be widened and deepened while preventing unfilled defects due to deformation of the portion.

[0031]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a schematic view of a friction stirrer for performing 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 in FIG. FIG. 3 is a detailed view of the rotary tool. FIG. 4 is a diagram showing a rotary tool having a spherical-type projection. FIG. 5 is a view showing a rotary tool having a cylindrical projection shape. FIG.
FIG. 3 is a view showing a rotary tool having a thread-cut type projection.

In the present embodiment, the surface treatment by friction stir
It is intended for aluminum alloy castings as an example of a surface-treated member, and is particularly used for surface modification of adjacent ports (intervals), pistons, brake disks, etc. formed in a cylinder head of an automobile. By agitating the surface modified region of the casting without melting it by frictional heat, the metal structure is refined, the eutectic silicon (Si) particles are uniformly dispersed, and casting defects are reduced.
Material properties such as thermal fatigue (low cycle fatigue) life, elongation, impact resistance and the like can be obtained more than conventional remelt treatment.

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

As shown in FIGS. 1 to 3, the friction stirrer 1 comprises a cylindrical rotary tool 4 having a spherical non-consumable projection 2 fixed or mounted on a shoulder 3 at the tip thereof, Tool driving means 5 is provided for relatively moving the tool 4 while pressing the surface reforming region of the member to be treated while rotating the tool 4 to rotate the protrusion 2.

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 or a robot arm. An apparatus capable of controlling the number of rotations, feed speed and pressing force of the apparatus is used. As another form, the rotating tool 4 may be rotatably supported, and the surface-treated member may be relatively moved in all directions, up, down, left, and right.

The protrusion 2 and the shoulder 3 of the rotary tool 4 are made of a steel material having a hardness higher than that of an aluminum alloy.
The shape of the protrusion 2 is formed as a spherical surface having a predetermined radius.
The rotary tool 4 has a first portion in which the protrusion 2 is formed on the shoulder 3.
A cylindrical shaft 6, a larger-diameter second cylindrical shaft 7 connected to the upper end of the first cylindrical shaft 6, and a larger diameter than the first cylindrical shaft 6 connected to the upper end of the second cylindrical shaft 7. The third cylindrical shaft 8 has a smaller diameter than the second cylindrical shaft 7. Third cylindrical part 8
Is attached to the tool driving means 5.

The shape of the protruding portion 2 includes a spherical type (FIG. 4), a cylindrical type (FIG. 5), a thread cutting type (FIG. 6), and the like. High stirring capacity is preferable.

In this embodiment, as shown in FIG. 7, AC4D, which is an aluminum alloy standardized by JIS, is used as an example of a member to be treated, 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 of 1 to 24% by weight, preferably 4 to 13% by weight. Besides, AC4B, AC2B, AC8A used for a piston, and the like can also be used. The upper limit of silicon content is 2
The reason for setting the content to 4% is that, even if silicon is further increased, material properties and castability are saturated, and agitation is deteriorated.

An aluminum alloy casting containing magnesium precipitates Mg ₂ Si by a heat treatment, thereby increasing the strength. However, when the metal structure is refined by melting as in a remelt treatment, magnesium having a low melting point (650 ° C.) may evaporate to reduce the content. When the magnesium content is reduced, the hardness and strength are reduced even if heat treatment is performed, so that 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 precipitating Si.

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

Eutectic silicon is hard and brittle, and serves as a starting point of crack generation and a propagation path, so that elongation is reduced. In addition, the fatigue life of a portion that is repeatedly subjected to thermal stress, such as an inter-valve portion, is reduced. In the metal structure, eutectic silicon is connected along the dendrite.However, cracking due to stress concentration and propagation of the generated cracks are suppressed by miniaturizing and uniformly dispersing the eutectic silicon. It is possible to do.

FIG. 8A is a diagram showing the processing depth according to the projection length, FIG. 8B is a diagram showing the projection length PL, and FIG. 8C is the maximum processing depth. It is a figure which shows Dmax. FIG. 9 is a diagram illustrating the processing depth according to the rotation speed and the feed speed of the rotary tool.

In this embodiment, the projection length PL is set to 80 to 90% of the required depth. The required depth is 1.1 to 1.2 times the length of the protruding portion, and can be set to about (0) to about 10 mm. Further, as shown in FIG. 8A, the maximum processing depth Dmax increases in proportion to the protruding portion length PL (1.1 to 1.2 times the protruding portion length), and the maximum processing width also increases. It increases in proportion to. Also, as shown in FIG.
The maximum processing depth Dmax is determined by the projection length PL, and it can be said that the influence of the number of rotations and the feed speed is small. Further, FIG.
The variation is smaller than the maximum processing depth by the remelt processing exemplified in (1), and the reliability can be improved.

In the case where the inter-valve portion of the cylinder head having a maximum compression pressure in the combustion chamber as high as about 150 kgf / cm ² as in this embodiment is subjected to surface treatment, the rotational speed of the rotary tool is increased to 1200 in consideration of productivity. It is preferable that the maximum processing depth Dmax is set to 4 mm or more (finishing allowance 1 mm or less) after finishing processing, at ~ 2400 rpm, feed rate 30 to 150 mm / min.

FIG. 10 is a diagram showing an example of an unfilled defect. FIG. 11 is a diagram illustrating a tilt angle of the rotary tool.

When the rotary tool is perpendicular to the processing surface under the above processing conditions (the tilt angle θ of the rotary tool is 0 °), it is possible to prevent unfilled defects occurring near the corner of the rotary tool shown in FIG. difficult. If the inclination angle θ is larger than 5 °, a deep groove is formed on the processing surface at the edge of the shoulder portion 3 of the rotary tool 4, and a lot of burrs are generated, so that the appearance is deteriorated, and a margin during finishing is reduced. It is not preferable because it increases. Therefore, as shown in FIG. 11, the rotary tool 4 is moved in a state in which the tilt angle θ is tilted in the direction opposite to the feed direction with respect to the surface of the surface treatment area in a range of 0 ° <θ ≦ 5 °, so that Filling defects can be suppressed, and the processing depth and feed rate can be further increased to improve productivity. [Method of Manufacturing Cylinder Head] Next, the process of manufacturing the cylinder head for a diesel engine according to the present embodiment will be described.

FIG. 12 is a flowchart illustrating the steps of manufacturing the cylinder head for a diesel engine according to the present 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 removed from the casting mold and the gate is deleted. In step S3, the casting removed from the casting mold is subjected to a T6 heat treatment mainly for sand removal.
In step S4, a surface treatment is applied to the inter-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 pre-remelting processing in step T4, the preheating of the casting in step T5, and the re-T6 heat treatment in step T4 in FIG. 34 are not required. Can be simplified and the manufacturing cost can be reduced. [Surface Treatment by Friction Stirring] Next, the friction stir processing of FIG. 12 will be described. <Surface Treatment of First Embodiment> FIGS.
It is a figure explaining a friction stir processing procedure of an interval between valves as an embodiment.

As a pre-process of the friction stir processing, as shown in FIG. 13, when the cylinder head H is cast, a line L1 connecting the centers of the adjacent intake port 14 and exhaust port 15 is formed.
The extra space 11 is provided at the extension of each port of the valve
And an intermediate body having a cast hole 12. The cast hole 12 may be machined with a drill or the like after casting, and is formed to have dimensions substantially the same as the diameter and length of the protrusion 2.

Next, as shown in FIG. 14, the projecting portion 2 is inserted into the cast hole 12 for positioning while being driven to rotate, and the shoulder portion 3 of the rotary tool 4 is pressed against the surface of the inter-valve portion 10. To determine the processing depth.

Subsequently, as shown in FIG. 15, a line L1 connecting the centers of the adjacent ports is set as the movement locus of the protrusion 2.
The protruding portion 2 is moved by the tool driving means 5 to the other surplus portion 11 while being stirred by friction along the movement locus, starting from the cast hole 12 of the one surplus portion 11. On this occasion,
An arc-shaped groove 16 is formed on the surface of the inter-valve portion along the line L1 by pressing the shoulder portion 3 of the rotary tool 4.

Further, as shown in FIG. 16, the protruding portion 2 is moved to the other excess portion 11 and then separated from the inter-valve portion 11. At this time, a terminal hole 13 is formed in the other excess portion 11 as an end point of the protrusion 2.

Finally, as shown in FIG.
And finish the intake port 14 and the exhaust port 15.

FIG. 18A is a diagram showing the direction of processing of the inter-valve portion by the remelting process, and FIG.
It is sectional drawing which shows the processing depth by the processing direction of (a).
FIG. 19A is a diagram showing the direction of the inter-valve portion processing by the friction stir processing of the present embodiment, and FIG.
It is sectional drawing which looked at the processing depth by the processing direction of (a) from the perpendicular direction with respect to the movement locus of a rotary tool. FIG. 20 is a cross-sectional view of the processing depth of the inter-valve portion by the friction stir processing of the present embodiment as viewed from a direction parallel to the movement locus of the protruding portion.

In the above-mentioned surface treatment, the line L1 connecting the centers of the adjacent intake port 14 and exhaust port 15 is defined by the protrusion 2
By traversing the intervalve portion 10 at the shortest distance as the movement trajectory of the
Therefore, the processing depth of the inter-valve portion 10 can be easily increased as compared with the remelting process performed at a right angle to the crack generation direction of the inter-valve portion 10 as shown in FIG. it can. The movement trajectory of the protruding portion 2 can be set not only in a line connecting the centers of adjacent ports, but also in other regions where cracks are likely to occur.

FIG. 21A is a cross-sectional view of the metal structure and the base material subjected to the surface treatment of the present embodiment.
(B) is a sectional view showing the metal structure and the base material of FIG. 21 (a) individually. FIG. 22A is a cross-sectional view showing a metal structure subjected to the surface treatment of the present embodiment, and FIG.
FIG. 2 is a cross-sectional view showing a metal structure subjected to a remelt treatment.

As shown in FIG. 21, fine eutectic silicon is uniformly dispersed by performing surface treatment by friction stirring, and a metal structure free from vacancy defects can be formed. Further, as shown in FIG. 22, a fine metal structure comparable to the remelt treatment can be formed. <Surface Treatment of Second Embodiment> As shown in FIG. 23, in the cross section of the processing area by the rotating tool whose protruding portion is clockwise rotated by the left-hand thread type, the material is pressed inside around the protruding portion of the tool. The portion where the flow of the material is in the same direction as the traveling direction of the rotary tool in the direction of rotation of the tool is a region where the plastic flow is shallow and the processing depth is shallow, and the area is small. The area in the opposite direction has a deep processing flow where the plastic flow is deep, and has a large area R
It becomes 2. The difference between the regions R1 and R2 is that the relative speed between the rotating tool and the material is rapidly and narrowly agitated in the same direction as the rotation of the tool, and is slowly and widely agitated in the opposite direction because the relative speed is low. Conceivable.

The shape of the protruding portion of the rotary tool is not limited to the thread cutting type, but can be applied to a spherical type (FIG. 4) or a cylindrical type (FIG. 5).

In the friction stir processing of the second embodiment, by utilizing this characteristic, a plurality of processing paths (FIG. 24) are overlapped so as to overlap the shallow region R2 of plastic flow so that the processing depth becomes substantially uniform. For example, in contrast to the first processing pattern for setting a reciprocating path, the second processing pattern for suppressing the outflow of the material by suppressing the processing depth by overlapping the region R1 having a deep plastic flow shown in FIG. Are used properly. Thus, a wide area can be processed by the rotary tool having a small protrusion, and in the first processing pattern,
As shown in FIG. 26, when the processing is performed so as to be as close to the port end as possible in the surface treatment of the cylinder head, if the processing is performed so that the narrow region R1 comes to the thinner side of the port end, the port as shown in FIG. End deformation can be avoided. In the first and second processing patterns, the maximum processing depth is overlapped so as to be substantially the same height, and the pushing amount of the shoulder portion of the rotary tool into the material is determined.

On the other hand, a drawback of surface treatment using a rotary tool having a projection is that a terminal hole of the projection remains at the end point of the processing path. Further, a defect is likely to occur at the processing start point, and in order to solve this, a processing path is set so as to pass through the start point. In the case of processing the surface of a casting in which drilling of bolts such as a cylinder head is performed in a later step, the end of the processing path is drilled by using a projection having a smaller diameter than the hole diameter in drilling. Set to position. Thereby, the terminal hole can be prevented from remaining in the product.

Next, the surface treatment of the cylinder head of an in-line multi-cylinder diesel engine using the friction stir processing of the second embodiment will be described.

As shown in FIG. 28, the cylinder head H
Has a pair of intake ports 14, a pair of exhaust ports 15 corresponding to a plurality of cylinders, and a plurality of tension bolt holes 21 for fastening to a cylinder block (not shown).
Here, there is a demand that the intake ports be made as large as possible in order to increase the amount of intake air, so that the space between adjacent intake ports becomes narrow and thin. The friction stir processing of the second embodiment is particularly effective for processing such a portion.

As an example of one processing path, FIG.
As shown in FIG. 7, tension is continuously processed from one end in the longitudinal direction of the cylinder head H to the other end so as to pass between a pair of the exhaust port 15 and the intake port 14 facing each other for one cylinder. A first path P1 ending at the bolt hole 21 and a pair of exhaust ports 15 and a pair of intake ports 14 facing each other from a cylinder adjacent to the end point of the first path P1 after the processing of the first path P1. Are sequentially processed and the second pass P2 having the tension bolt hole 21 as an end point
Through P5, the surface of the cylinder head H is stirred and reformed without being melted by the heat of the rotary tool.

As another example of the processing path relating to the first processing pattern, as shown in FIG. 29, the exhaust port 15 and the intake port
And a first forward pass Q1 ending at the tension bolt hole 21 by continuously processing from one end in the longitudinal direction of the cylinder head H to the other end so as to pass between the pair of the four heads.
The cylinder head H is arranged to pass between a pair of the exhaust port 15 and the intake port 14 in parallel in a direction opposite to the outward path Q1.
The first return path Q2 which is continuously processed from the other end in the longitudinal direction to the one end in the first direction and has the tension bolt hole 21 as an end point.
After the processing of the first return path Q2, the cylinder reciprocates between the pair of exhaust ports 15 and the pair of intake ports 14 facing each other from the cylinder adjacent to the end point of the first return path Q2, and the start point of the outward path in the return path. Qs, and the second reciprocating path Q having the tension bolt hole 21 as an end point.
After 3 to Q6, the surface of the cylinder head H is stirred and reformed without being melted by the heat of the rotary tool.

As described above, by setting a processing path for the cylinder head H, a wide area can be processed only at a necessary portion, so that the residual stress can be reduced and the processing time can be shortened. On the other hand, as shown in FIG.
When the remelting process is performed in the shape of a figure 8 between ports, port 1
It is necessary to process substantially the entire area between 4 and 15.

Further, since the processing time can be shortened, deformation of the material can be suppressed. On the other hand, when the remelt processing is performed in the shape of the figure 8, the processing path becomes short, but the material passes through the vicinity of the port, so that the material is easily deformed.

Further, in the reciprocating path, since the temperature distributions of the materials in the forward pass and the return pass are different, there is an advantage that the material is hardly deformed. When the processing is performed in the shape of the figure 8, the material resistance in the overlapping portion of the processing area decreases, and the material is easily deformed.

In the surface treatment of the cylinder head, the inclination angle θ of the rotating tool is 0 ° and the number of rotations is 600 to 1000 rpm.
m, feed speed 300-500 mm / min, protrusion length 5.8 mm, protrusion diameter 7 ± 1 mm, shoulder diameter 1
Assuming that 5 ± 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. In addition, each dimension is set as 2 <shoulder part / projection part <4 with respect to a protrusion part diameter and a shoulder part diameter. In addition, the amount of pushing of the material of the shoulder to the processing surface is set to 1 mm or less. [Heat Treatment After Surface Treatment] FIG. 31 is a diagram showing a comparison between the hardness when the T6 heat treatment is performed after the surface treatment by stirring and the hardness when the T6 heat treatment is not performed. FIG. 32 is a diagram comparing the mechanical properties of the case where only the T6 heat treatment is performed after the surface treatment by stirring and the case where the T6 heat treatment is performed after the remelt treatment. FIG. 33 is a diagram showing the relationship between the initial hardness and the thermal fatigue life, which change according to the difference in heat treatment.

In addition to the above-described surface treatment by friction stirring, when heat treatment is performed before finishing, compared with the case without heat treatment, both the surface treatment structure and the base material underneath as shown in FIG. Hv) can be increased.
In addition, as shown in FIG. 32, those obtained by performing only T6 treatment, those subjected to T6 heat treatment after remelting treatment, and those subjected to only friction stir treatment can obtain excellent tensile strength and elongation characteristics as compared with each mechanical property. it can.

As can be seen from FIG. 33, when no heat treatment is performed, the initial hardness is low and the elongation characteristics are high, so that the thermal fatigue life is increased and the strength against thermal shock is increased. Therefore, it is effective to use a portion requiring high thermal fatigue strength in a state where only the friction stir processing is performed and the elongation property is high.

On the other hand, in a portion where thermal fatigue and mechanical high cycle fatigue are superimposed, not only elongation but also strength is required. Therefore, in order to achieve both high strength and elongation, friction stirring is performed. It is effective to perform the treatment and the T6 heat treatment.
Further, even in the case where the vicinity of the treated structure is softened due to the influence of heat and the strength is reduced, the T6 heat treatment is effective for recovering the strength.

As an example of the heat treatment, JIS standard T6 heat treatment (solution treatment and aging treatment) is effective. In the solution treatment, the solution is kept at a solution solution temperature of 535 ° C. (± 5 ° C.) for 4 hours and then quenched with boiling water. The aging treatment is performed at an aging temperature of 18
After holding at 0 ° C. (± 5 ° C.) for 6 hours, air-cool.

[Brief description of the drawings]

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

FIG. 2 is an enlarged view of the vicinity of a pin-shaped tool in FIG.

FIG. 3 is a detailed view of a pin-shaped tool.

FIG. 4 is a view showing the shape of a spherical type tip pin.

FIG. 5 is a view showing the shape of a tip pin of a cylindrical type.

FIG. 6 is a view showing a shape of a tip pin of a thread cutting type.

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

8A is a diagram illustrating a processing depth according to a tip pin length, FIG. 8B is a diagram illustrating a tip pin length PL, and FIG. 8C is a diagram illustrating a maximum processing depth Dmax.

FIG. 9 is a diagram showing a processing depth according to the rotation speed and the feed speed of the pin-shaped tool.

FIG. 10 is a diagram showing an example of an unfilled defect.

FIG. 11 is a view showing an inclination angle of a pin-shaped tool.

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

FIG. 13 is a diagram illustrating a surface treatment procedure of an inter-valve portion.

FIG. 14 is a diagram illustrating a surface treatment procedure of an inter-valve portion.

FIG. 15 is a diagram illustrating a surface treatment procedure of an inter-valve portion.

FIG. 16 is a diagram illustrating a surface treatment procedure of an inter-valve portion.

FIG. 17 is a view for explaining a surface treatment procedure of an inter-valve portion.

18A is a diagram illustrating a processing direction of an inter-valve portion by a remelt process, and FIG. 18B is a cross-sectional view illustrating a processing depth in the processing direction of FIG.

FIG. 19A is a diagram showing a processing direction of an inter-valve portion by the friction stir processing of the present embodiment, and FIG. 19B is a drawing showing a processing depth in the processing direction of FIG. FIG. 4 is a cross-sectional view as viewed from a direction perpendicular to the direction.

FIG. 20 is a cross-sectional view of the processing depth of the inter-valve portion by the friction stir processing of the present embodiment, as viewed from a direction parallel to the movement locus of the pin-shaped tool.

21A is a cross-sectional view of a metal structure and a base material subjected to the surface treatment of the present embodiment, and FIG. 21B is a cross-sectional view showing the metal structure and the base material of FIG. is there.

FIG. 22 (a) is a cross-sectional view showing a metal structure subjected to the surface treatment of the present embodiment, and FIG. 22 (b) is a cross-sectional view showing the metal structure subjected to the remelt treatment.

FIG. 23 is a diagram illustrating characteristics of the friction stir processing according to the second embodiment, and is a view illustrating a traveling direction of a rotary tool and a cross section of a material processing region.

FIG. 24 is a diagram showing a cross section of a processing region of a material according to a first processing pattern in the friction stir processing of the second embodiment.

FIG. 25 is a diagram showing a cross section of a processing region of a material according to a second processing pattern in the friction stir processing of the second embodiment.

FIG. 26 is a diagram illustrating a bad example in the case of processing a port end;

FIG. 27 is a diagram illustrating a good example of processing a port end.

FIG. 28 is a diagram showing one example of a processing path, which is a surface processing of a cylinder head of an in-line multi-cylinder diesel engine using the friction stir processing of the second embodiment.

FIG. 29 is a diagram showing another example of a processing path, which is a surface processing of a cylinder head of an in-line multi-cylinder diesel engine using the friction stir processing of the second embodiment.

FIG. 30 is a diagram showing an example of a surface treatment of a cylinder head of an in-line multi-cylinder diesel engine using a conventional remelt process.

FIG. 31 is a diagram showing a comparison between hardness when a T6 heat treatment is performed after surface treatment by stirring and when no T6 heat treatment is performed.

FIG. 32: T6 heat treatment only, T after surface treatment by stirring
FIG. 6 is a diagram showing a comparison between tensile strength and elongation characteristics when a T6 heat treatment is performed after a remelt treatment when a 6 heat treatment is performed.

FIG. 33 is a diagram showing the relationship between initial hardness and thermal fatigue life, which changes according to the difference in heat treatment.

FIG. 34 is a flowchart illustrating a manufacturing process of a conventional cylinder head for a diesel engine.

FIG. 35 is a diagram illustrating an outline of a remelt process.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Friction stirrer 2 Projection part 3 Shoulder part 4 Rotary tool 5 Tool drive means 10 Inter-valve part 11 Extra part 12 Cast-out hole 13 Termination hole H Cylinder head

Claims (9)

[Claims] 1. A surface treatment method for agitating and reforming the surface of a casting having a recess without being melted by heat of a rotary tool, wherein the surface treatment of the rotary tool in a region closest to the recess. A surface treatment method comprising: performing a surface treatment such that a flow of a material between the recess and the rotating tool is in a direction opposite to a traveling direction of the rotating tool. 2. A surface treatment method for agitating and reforming the surface of a casting having a recess without being melted by heat of a rotary tool, wherein the surface treatment of the rotary tool in a region closest to the recess. A surface treatment method comprising: performing a surface treatment such that a flow of a material between the recess and the rotary tool is in the same direction as a traveling direction of the rotary tool. 3. A surface treatment method for agitating and modifying a surface of a casting to be drilled without being melted by heat of a rotary tool, wherein a rotary tool having a smaller diameter than a hole diameter in the drilling is used. Wherein the surface treatment is performed such that an end point of the surface treatment path by the rotary tool is a position where the drilling is performed. 4. The method according to claim 1, further comprising the step of modifying the space between the recesses with the rotary tool, and setting the surface treatment path so that the modified regions overlap each other. The surface treatment method according to claim 1. 5. The surface treatment method according to claim 1, wherein an end point of the surface treatment path is set so as to pass through a start point of the surface treatment path. 6. The cylinder head having a pair of intake ports and a pair of exhaust ports corresponding to a plurality of cylinders, wherein the cylinder head passes between the pair of exhaust ports and the pair of intake ports. 4. The method according to claim 1, wherein after performing continuous processing in the longitudinal direction of the cylinder head, surface processing is performed so as to pass between the pair of the exhaust port and the intake port from a cylinder adjacent to the position. 2. The surface treatment method according to claim 1. 7. A processing member having a recess, the surface of which is agitated and modified without being melted by the heat of the rotating tool, wherein the surface treatment of the rotating tool in a region closest to the recess. A processing member having a surface processed so that a flow of a material between the recess and the rotating tool is in a direction opposite to a traveling direction of the rotating tool. 8. A processing member having a recess, the surface of which is agitated and modified without being melted by the heat of the rotary tool, wherein the surface treatment of the rotary tool in a region closest to the recess. A processing member, wherein a path is subjected to a surface treatment so that a flow of a material between the recess and the rotary tool is in the same direction as a traveling direction of the rotary tool. 9. A processing member which is subjected to drilling and is reformed by agitating the surface without being melted by the heat of the rotary tool, using a rotary tool having a smaller diameter than the hole diameter in the drilling, A processing member, wherein a surface treatment is performed so that an end point of a surface processing path by the rotary tool is a position where the drilling is performed.