JP2003048064A - Surface treatment method, surface treatment apparatus and member applied with the surface treatment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform a friction-stirring treatment and a burr-removal work by using the same machine tool, to restrain variation of treated depth caused by thermal expansion of a rotary tool and to thereby prevent non-filling defect. SOLUTION: A machine tool 100 with a tool changer 101 is used. The tool changer 101 holds at least two rotary tools 4 each having the same shape and at least one burr-removal tool T. After treatment with the burr-removal tool T, the rotary tool 4 other than the tool 4 used just before is selected to alternately perform surface treatment and removal work of burrs caused by the surface treatment.

Description

Detailed Description of the Invention

[0001]

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

[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]

When a single rotary tool is used to continuously perform surface treatment by friction stirring, the higher the actual operating rate of the surface treatment equipment, the more the friction generated between the workpiece and the rotary tool. The heat is likely to be accumulated in the rotary tool, the thermal expansion amount of the tool itself or the spindle for mounting the tool is increased, and the position of the protrusion with respect to the work surface is changed.

Due to the influence of this change, although the NC control data is the same, the pushing amount of the rotary tool with respect to the work surface becomes larger in the warm state than in the cold state. As a result, the depth of the surface modified region varies, and the occurrence of internal unfilled defects is affected.

The present invention has been made in view of the above problems, and an object thereof is to perform friction stir processing and deburring processing using the same machine tool, and suppress variations in processing depth due to thermal expansion of a rotary tool. Surface treatment method that can prevent unfilled defects,
A surface treatment apparatus and a member subjected to the surface treatment are provided.

[0006]

In order to solve the above-mentioned problems and to achieve the object, a surface treatment method of the present invention provides a rotary tool detachably supported by tool supporting means of a machine tool on the surface of a work. A surface treatment method of inserting and modifying a work surface without melting the work surface by frictional heat generated by the rotation of the rotary tool, wherein the surface treatment area of the work is stirred by the rotary tool, and the rotation is performed. The tool is changed to a deburring tool that removes burrs from the work, and the surface treatment area is processed by the deburring tool.

Further, preferably, a plurality of rotary tools are provided, and a rotary tool different from the rotary tool used immediately after the treatment by the deburring tool is selected.

The surface treatment apparatus of the present invention inserts a rotary tool, which is detachably supported by tool supporting means of a machine tool, into a work surface, and melts the work surface by frictional heat generated by the rotation of the rotary tool. A surface treatment apparatus for agitating and modifying without modification, wherein a rotary tool driving means for agitating the surface treatment area of the work by the rotary tool and a deburring tool for removing the burr of the work are changed. The tool changing unit and the tool driving unit include a deburring tool driving unit that processes the surface treatment area with the deburring tool.

In the surface-treated member of the present invention, the rotary tool detachably supported by the tool supporting means of the machine tool is inserted into the member surface, and the frictional heat generated by the rotation of the rotary tool causes the surface of the member to rotate. A member which has been subjected to a surface treatment for stirring and modifying without melting, and a friction stirrer in which a surface treatment region of the member is stirred by the rotating tool, and the surface after friction stirring by the rotating tool. And a deburring section which is processed by changing to a deburring tool for removing burrs in the processing area.

[0010]

As described above, according to the inventions of claims 1, 3, and 4, the rotary tool detachably supported by the tool supporting means of the machine tool is inserted into the surface of the work, and the surface is friction-stirred. When processing, the surface treatment area of the work is agitated with a rotating tool, the rotating tool is changed to a deburring tool that removes burrs on the workpiece, and the surface treatment area is processed with the deburring tool, so that the same machine tool is used. The friction stir processing and the burr removal processing can be performed by using, and variations in processing depth due to thermal expansion of the rotary tool can be suppressed, and unfilled defects can be prevented.

According to the second aspect of the present invention, the rotary tool used immediately before is selected by having a plurality of rotary tools and selecting a rotary tool different from the rotary tool used immediately after the treatment with the deburring tool. To allow a sufficient cooling period.

[0012]

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 is an example as a means for realizing the present invention, and the present invention can be applied to a modified or modified form of the following embodiment without departing from the spirit of the present 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.

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 3, in the friction stirrer 1, a thread is formed on an outer peripheral surface having a diameter smaller than that of the shoulder portion 3 on a flat shoulder portion 3 at one end of a cylindrical shaft body. A rotary tool 4 on which the non-consumable protrusion 2 is integrally formed or attached, and the protrusion 2 is inserted into the surface modification region of the workpiece while rotating the rotary tool 4 to drive the protrusion 2 to rotate. Tool driving means 5 for relatively moving the work surface while pressing it with the shoulder portion 3, and a jig (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 or a robot arm. 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 shaft of a machine tool such as a machining center described later, and the work is relatively moved in the vertical direction and the horizontal direction with respect to the rotary tool 4. It may be moved two-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 protrusion 2 is formed in a thread shape with a predetermined pitch. Has been done.

In this embodiment, as shown in FIG. 4, 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.

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.

FIG. 5 (a) is a diagram showing the processing depth according to the protruding portion length, FIG. 5 (b) is a diagram showing the protruding portion length PL, and FIG. 5 (c) is the maximum processing depth. It is a figure which shows Dmax. FIG. 6 is a diagram showing the processing depth according to the rotation speed and the feed rate 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 10 mm. Further, as shown in FIG. 5A, the maximum processing depth Dmax is increased in proportion to the protrusion length PL (1.1 to 1.2 times the protrusion length), and the maximum processing width is also the protrusion diameter. Increases in proportion to. Further, as shown in FIG. 5B, the maximum processing depth Dmax is determined by the protrusion length PL, and it can be said that the influence of the rotation speed and the feed speed is small. Further, the variation is smaller than the maximum processing depth by the remelt processing illustrated in FIG. 6, and the reliability can be improved.

FIG. 7 is a view showing the basic shape of the vicinity of the port of the cylinder head material for a diesel engine before finishing, which is subjected to the surface treatment by friction stirring according to this embodiment.
FIG. 8 is a sectional view taken along line I-I of FIG. 7. FIG. 9 is a diagram showing a characteristic shape of the vicinity of the port of the cylinder head material for a diesel engine before finishing, which is subjected to the surface treatment by friction stirring according to the present embodiment. FIG. 10 shows II-I of FIG.
FIG.

Intervalve 1 with port openings on both sides
In No. 6, since volume expansion due to combustion of the engine and volume contraction due to cooling are repeated, cracks due to thermal fatigue are likely to occur. Therefore, by performing surface treatment on the intervalve portion 16 by friction stirring to realize a finer metal structure and a lower porosity area ratio, the proof stress against the occurrence and propagation of cracks due to thermal fatigue is increased, and thermal fatigue is increased. The strength can be improved.

However, the inter-valve portion 16 has a low work rigidity due to the presence of the port openings 14 and 15, and the rotary tool 4
Due to the pressing force and the rotation moment, the base material structures on the side surfaces of the openings 14 and 15 are plastically deformed in the vertical and horizontal directions, and the shapes of the port openings 14 and 15 change.

When the shapes of the port openings 14 and 15 change, the material that has plastically flowed due to friction stirring also moves to the port opening side, and the material filled in the exhaust port opening 15 side of the protrusion 2 decreases. Tunnel-shaped unfilled defects are likely to occur along the movement trajectory Q inside the surface modification region.

As shown in FIGS. 7 and 8, the surface modification region is located between the intake port opening 14 shown by the contour of the shoulder portion 3 of the rotary tool 4 and the movement locus Q to the exhaust port opening 15.
And the intake port opening 14 and the exhaust port opening 15
Is set between. Further, the port openings 14, 1 adjacent to the surface modification region are arranged so that the shoulder portion 3 of the rotary tool 4 contacts the work surface in the entire surface treatment process.
The shapes of the edges 14a, 14b, 15a, 15b of 5 are linearly formed along the movement trajectory of the rotary tool 4.

By thus forming the edges 14a, 14b, 15a, 15b of the port openings 14, 15 linearly, the apparent intervalvular portion 16 has the same width over the entire surface modified region. However, as shown in FIG.
The cross-sectional shape (wall thickness) of the intake port opening 14 is smaller than that of the exhaust port opening 15 due to the restriction of the port shape of the portion that is not machined. Due to the difference in work rigidity due to the difference in cross-sectional shape, the vertical plastic deformation of the base metal structure due to the indentation of the rotary tool 4 and the horizontal plastic deformation due to the rotation moment are less than the exhaust port opening 15. It tends to occur in the intake port opening 14.

As a result, the material that has plastically flowed due to the surface treatment by friction stirring easily fills the intake port opening 14 side where the base material is deformed, and the material that fills the exhaust port opening 15 side of the protruding portion 2. Is reduced, and tunnel-shaped unfilled defects are likely to occur along the movement locus Q inside the surface modification region.

This unfilled defect usually occurs in a tunnel shape along the movement locus Q of the rotary tool 4 and has a larger area (volume) than the cavity of the base metal, so that cracks due to thermal fatigue may occur. The proof stress against propagation increases, and the desired thermal fatigue strength cannot be obtained.

Therefore, in the present embodiment, with the port shown in FIGS. 7 and 8 as a basic shape, as shown in FIGS. 9 and 10, a movement locus Q having a width of about 4 mm and a height of about 5 mm is formed in the intake port opening 14. The two beams 17 and 18 orthogonal to each other are formed as extra portions that prevent deformation of the material of the opening 14 due to softening.

The beams 17 and 18 are formed at the same time when the work is cast by providing a transfer portion for forming the beam on the work casting mold, and this mold is placed on the upper side. Therefore, the beams 17 and 18 can be formed without increasing the number of manufacturing processes.

Due to the presence of the beams 17 and 18, the lateral deformation resistance of the side surface of the intake port opening 14 is significantly increased, and since the cantilever structure becomes a double-supported beam structure, the vertical deformation resistance is increased. It is also possible to suppress the deformation of the port opening and the occurrence of unfilled defects due to this deformation.

Further, since the beams 17 and 18 are removed together with the linear shape portion in the finishing process, no adverse effect on the intake efficiency occurs.

In the above example, the beam is provided only in the intake port opening 14 having a relatively low work rigidity, but it may be provided in the exhaust port opening 15 depending on the port shape. Also,
Regarding the width and height of the beams 17 and 18, the dimensions may be changed as necessary in consideration of the wall thickness of the port opening, or the beams 17 and 18 may be formed in a T shape instead of the orthogonal shape.

Further, if there is little influence on the productivity reduction in the finishing process, the port opening may be completely closed at the time of casting the work, or the port opening diameter φ1 shown in FIG. 7 may be reduced to finish. The shape may satisfy φ1 ≦ φ2 / 2 with respect to the subsequent port inner diameter φ2. In this case, since the shape of the port opening is circular and there is no linear portion, deformation can be reduced. [Cylinder Head Manufacturing Method] Next, a manufacturing process of the diesel engine cylinder head according to the present embodiment will be described.

FIG. 11 is a flow chart for explaining the manufacturing process of the diesel engine cylinder head of this embodiment.

As shown in FIG. 11, in step S1, a cylinder head as an intermediate body 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. [Surface Treatment by Friction Stirring] Next, step S in FIG.
The friction stir processing in No. 4 will be described.

In the surface treatment by friction stirring, the end hole having the projected shape transferred is left at the end point of the treatment, but the end hole is avoided if the end hole position is the portion to be drilled in the subsequent process. can do. However, the diameter of the protruding portion needs to be equal to or smaller than the diameter of the post-machining hole, and depending on the machining shape specifications and surface treatment specifications of the workpiece, the movement trajectory Q of the rotary tool 4
It is necessary to perform reciprocal movement while offsetting each other and to perform processing twice or more.

At this time, as described with reference to FIGS. 7 to 10, the cross-sectional shape (thickness) of the intervalve portion 16 is restricted to the intake port opening portion 14 rather than the exhaust port opening portion 15 due to the restriction of the port shape of the portion which is not machined. Is thin.
Due to the difference in work rigidity due to this difference in cross-sectional shape, the vertical plastic deformation of the base metal structure due to the indentation of the rotary tool 4 and the horizontal plastic deformation due to the rotation moment are
It occurs more easily in the intake port opening 14 than in the exhaust port opening 15.

In the second return path processing area, frictional heat due to the first forward path processing is conducted, so that the Young's modulus lowers and is easily deformed as the temperature rises, and the machining allowance in the subsequent step increases. At the same time, when the amount of deformation becomes excessive, the flow of the material is promoted in the deformed direction, so that the material filled on the side opposite to the deformed direction is reduced, and a tunnel is formed along the movement trajectory Q inside the surface modification region. Unfilled defects are likely to occur.

Therefore, in the present embodiment, a portion having high rigidity (exhaust port opening side) due to the shape of the intervalve portion is set as the processing region of the second return path, and the adverse effect of the Young's modulus lowering due to the temperature rise is adversely affected. The amount of deformation is reduced and the generation of unfilled defects is prevented.

As shown in FIG. 13, the processing path P2 of the second return path is set to a portion where the work rigidity is low (the intake port opening 1).
4 side), while the exhaust port opening 15 in the portion where the work rigidity is high maintains the original shape,
A region where the work rigidity is low is largely deformed, and the flow of the material due to this deformation causes an unfilled defect inside the surface modification region.

On the other hand, as shown in FIG. 12, when the processing path P2 of the second return path is set on the exhaust port opening 15 side of the portion having high work rigidity, both the portion having high work rigidity and the portion having low work rigidity have port openings. Nos. 14 and 15 generally maintain the original shape, and it is possible to suppress the occurrence of unfilled defects inside the surface modified region.

A drawback 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. Further, a defect is likely to occur even at the processing start point, and in order to solve this, the processing path is set so as to pass through the processing start point. Also,
When processing the surface of the casting such as the cylinder head where the drilling of bolts is performed in the subsequent process, use the protrusion with a diameter smaller than the diameter of the hole in the drilling, and set the end point of the processing route to the position where the drilling is performed. Set. This allows the product to have no end holes.

FIG. 14 is a diagram 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. 14, 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 the intake port opening 14 is required to be as large as possible in order to make the intake amount large, the space between the adjacent intake ports becomes narrow and thin.

Therefore, in the present embodiment, as an example of the processing path, the cylinder head material H is longitudinally passed so as to pass between a pair of the exhaust port opening 15 and the intake port opening 14 which face each other for one cylinder. In the opposite direction from the first outward path Q1 that is continuously processed from one end to the other end and ends at the tension bolt hole 21 and is folded back at the other end of the cylinder head material H. The tension bolt hole 21 is continuously processed from the other end in the longitudinal direction of the cylinder head material H toward one end so as to be offset and run in parallel between the pair of the exhaust port opening 15 and the intake port opening 14. First return pass Q2, which is the end point
Then, after the processing of the first return path Q2, the processing is sequentially performed while reciprocating between the pair of exhaust ports 15 and the pair of intake ports 14 facing each other from the cylinder adjacent to the turning position to the first return path Q2. 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 stirred and reformed without being melted by the heat of the rotary tool.

In the second reciprocating paths Q3 to Q6, the processing path offset to the intake port opening 14 side, which is a portion having a low work rigidity, is used as the outward path, and is offset to the exhaust port opening 15 side, a portion having a high work rigidity. The route becomes a continuous round trip route with the return route as the return route, and the processing regions of the forward route and the return route overlap.

Like this second round trip path Q3 to Q6, 2
By setting the processing path of the return path at the side of the exhaust port opening 15 which is a part with high work rigidity, deformation is generated not only in the part with high work rigidity but also in the intake port opening with low work rigidity. In addition, the generation of unfilled defects inside the surface modified region can be suppressed.

In the surface treatment of the cylinder head, the rotational speed of the rotary tool is 700 to 1100 rpm and the feed rate is 4
00 to 550 mm / min, the protrusion length is 5 to 6 mm,
It is desirable that the diameter of the protruding portion is 7 ± 1 mm and the diameter of the shoulder portion is 15 ± 1 mm so that the total processing width of the first pass and the second pass is equal to or less than the intervalve width of the material −2 mm.
The projection diameter and the shoulder diameter are set so that 2 ≦ shoulder portion / projection portion <4. Further, the pushing amount of the shoulder portion with respect to the material-treated surface is set to 0.3 mm or more. [Machine tool as tool driving means] When continuously performing surface treatment by friction stirring using a single rotary tool, the higher the actual operating rate of the surface treatment equipment, the more the friction generated between the workpiece and the rotary tool. The heat is likely to be accumulated in the rotary tool, the thermal expansion amount of the tool itself or the spindle for mounting the tool is increased, and the position of the protrusion with respect to the work surface is changed.

Due to the influence of this change, although the NC control data are the same, the pushing amount of the rotary tool with respect to the work surface becomes larger in the warm state than in the cold state. As a result, the depth of the surface modified region varies, and the occurrence of internal unfilled defects is affected.

On the other hand, in the case of the surface treatment by friction stirring, since the shoulder portion of the rotary tool is moved while being pressed against the work surface, burrs are generated on the work surface corresponding to the outer peripheral edge portion of the shoulder portion. It is also necessary to remove the burrs to remove the burr.

Therefore, in this embodiment, a machine tool having a tool changer is used, or a machine tool is provided with a tool changer to hold at least two rotary tools of the same shape and to remove the burr. At least one of them is held, and a rotating tool different from the rotating tool used immediately after the treatment by the deburring tool is selected, and the surface treatment by friction stirring and the deburring processing generated by this surface treatment are alternately performed. To run.

By this method, the waiting time per rotating tool can be extended from the burr removal processing time by the surface treatment time × the number of holdings of the rotating tool, and the temperature of the rotating tool can be lowered during the waiting time. It is possible to suppress the variation in the depth of the surface modification region due to the thermal expansion of the spindle.

FIG. 15 is a schematic front view of a machine tool as a tool driving means.

As shown in FIG. 15, the machine tool 100 is
A tool changer 101 that removably supports the rotary tool 4 and the burr removal tool T, and the rotary tool 4 or the burr removal tool T is selected according to an NC control program to rotate around the tool center axis and can move vertically. Spindle 102
And an XY table 103 that holds the work facing the tool and moves the work two-dimensionally relative to the tool, and is numerically controlled according to an NC control program stored in a controller (not shown). It The workpiece is the machining reference hole 22 (see FIG.
4) and positioned and held.

As a first processing example of this embodiment, the tool changer 101 includes five rotary tools 4A-4 having the same shape.
E, Milling cutter T1 as one burr removal tool
, And the processing time per work piece is about 6 minutes. The breakdown is 1 minute 20 seconds for work replacement, 4 minutes for surface treatment, 1 minute 20 seconds for deburring processing, the first rotating tool After using 4A, the tools are sequentially replaced in the procedure shown in FIG. 16 to continuously process 31 workpieces.

The number of rotary tools attached to the tool changer 101 is at least 20 after the use of a certain rotary tool until the next use of the rotary tool.
It is preferable that the time is longer than a minute and sufficient cooling is possible.

The surface of the rotary tool was directly measured by using a thermometer for each of the first, 11th, 21st and 31st workpieces processed by using the first rotary tool 4A immediately before the start of processing. The temperature was measured.

Further, as a second processing example of this embodiment,
The tool changer 101 holds one rotary tool 4 and one milling cutter T1, respectively, and the processing time per work piece and its breakdown are the same as those in the first processing example.
In the procedure shown in FIG. 7, the tool is exchanged alternately and 31 workpieces are continuously processed.

Similarly, for each of the first, eleventh, twenty-first and thirty-first workpieces processed by using the first rotary tool 4A, the rotary tool of the rotary tool is directly used immediately before the start of processing. The surface temperature was measured.

FIG. 18 shows the temperatures measured for the first, eleventh, twenty-first, and thirty-first workpieces after the 31st continuous treatment by the first and second treatment examples is completed. According to the first processing example, the processing depth is substantially constant, no internal unfilled defects occur, and the surface temperature of the rotary tool does not change significantly, and good results are obtained. Was given.

On the other hand, in the second processing example, the surface temperature of the rotary tool from the first to the eleventh and from the eleventh to the twenty-first rapidly increases, and the processing depth gradually increases accordingly. Internal unfilled defects occurred in the eye and the 31st work.

As in the first processing example, the processing time per rotating tool is the processing time per workpiece × the number of rotating tools (about 30 minutes), and the substantial waiting time of the rotating tools is about 6 minutes. When the amount is secured, the frictional heat accumulated in the rotary tool is radiated within the waiting time, the temperature after the eleventh work is almost constant, and the variation width of the processing depth is 0.15.
Although it is mm, there is no correlation with the tool temperature or the cumulative number of processes.

On the other hand, in the second processing example, since the waiting time of the rotary tool is only about 2 minutes, the next processing is started before the frictional heat accumulated in the rotary tool is radiated. Therefore, the surface temperature of the tool and the processing depth tend to increase with the passage of time until the cumulative number of processed objects reaches the 21st. The processing depth increases with the lapse of time because the amount of tool indentation increases due to thermal expansion.
The reason why the unfilled defects occurred only in the 21st and 31st parts was that the amount of pushing of the tool increased due to thermal expansion.

In the case of the second processing example, good results cannot be obtained under the same conditions as in the first processing example, but the moving path of the rotary tool is long (processing time is long), and the required processing is performed. When the depth is large and the work thickness in the surface modification region is large, it can be an effective processing procedure. Further, the rotary tool may be forcibly cooled by blowing air or the like. [Other processing example] As another processing example other than the surface treatment by the tool changer, the surface temperature of the rotary tool is measured by using a temperature sensor or the like immediately before the surface treatment by friction stirring is started, or by using a touch sensor or the like. Measure the amount of thermal expansion of the rotating tool and correct the pushing amount of the rotating tool according to these measured values, or prepare multiple NC control programs in advance, and select the appropriate NC corresponding to the measured value for each workpiece.
A surface treatment may be performed by selecting a control program.

By this method, even when the rotary tool thermally expands due to frictional heat, the tool indentation amount can be controlled to be substantially constant, and the variation in the depth of the surface modification region and the occurrence of internal unfilled defects can be suppressed. be able to.

As a concrete example of processing, the processing time for one work is about 7 minutes, and the details are as follows: (i) 1 minute and 20 seconds for changing the work, (ii) 1 for measuring the surface temperature of the rotary tool.
Min 10 seconds, (iii) 30 for measuring the thermal expansion of rotating tools
Second, the surface treatment is (iv) 4 minutes, and the processing sequence is (i) → (iv).

The surface temperature measurement of (ii) above is
A contact thermometer or the like is used as an axial center portion 3a of the outer peripheral side surface of the shoulder portion 3 of the rotary tool 4 shown in FIG. Further, the measurement of the thermal expansion amount of the rotary tool 4 in (iii) is performed by using a dial gauge or the like as the measurement site for the displacement amount of the step portion 3b formed on the outer peripheral side surface of the shoulder portion 3 of the rotary tool 4 shown in FIG. . The step portion 3b is the rotary tool 4
It is formed by grinding a portion that is as close as possible to the tip of the and is not inserted into the work. The tip of the protruding portion 2 of the rotary tool 4 and the end surface of the shoulder portion 3 are not used as measurement sites because the materials agitated by the surface treatment adhere to these sites and the value obtained by adding the film thickness of the material to the thermal expansion amount. Is measured.

FIG. 20 shows tool position measurement data based on the surface temperature and thermal expansion of the tool when 10 rotary workpieces are continuously processed by one rotary tool according to the above processing procedure,
It can be seen that the surface temperature of the rotary tool rises as the cumulative number of treatments increases, and the tool thermally expands and extends in the axial direction due to the temperature rise. Therefore, if the same NC control program is used, the amount of tool indentation changes due to the thermal expansion of the rotating tool, resulting in variations in the processing depth and internal non-filling defects.

Based on the above results, the rotary tool was attached to the spindle of the machine tool, and the vertical position of the thermal expansion measurement site was measured using a touch sensor or the like immediately before the start of the surface treatment by friction agitation. The tool pushing amount is corrected or a proper NC control program is selected and changed to control the tool pushing amount to a constant value.

Since the correlation shown by the following functional expression is recognized between the surface temperature of the tool and the amount of thermal expansion shown in FIG. 20, the surface temperature of the tool is used as a surrogate characteristic of the amount of thermal expansion of the tool. The measurement is performed before the processing is started, and the tool pressing amount is corrected according to the measured value, or an appropriate NC control program is selected and changed to control the tool pressing amount to be constant.

(ΔT−T) × α × L = ΔL where T: initial surface temperature of the rotary tool, ΔT: surface temperature of the rotary tool after temperature rise, L: initial length of the rotary tool, Δ
L: Length of rotary tool after temperature ΔT rises (after thermal expansion),
α: Coefficient of linear expansion of rotating tool Since a correlation coefficient R≈0.975 is recognized between the surface temperature and the amount of thermal expansion of the tool shown in FIG. 20, the coefficient of thermal expansion of the tool As a substitute characteristic, the tool surface temperature is measured before the surface treatment is started, and the tool pressing amount is corrected according to the measured value and the correlation coefficient, or the tool pressing amount is fixed by selecting / changing an appropriate NC control program. You may control to.

By using one or both of the above or both, even if the tool or the spindle of the machine tool thermally expands due to the temperature rise of the rotary tool, the processing depth can be stabilized. [Inspection Method for Defects of Surface-treated Member] Generally, a defect generated in the surface-modified region is detected by human visual observation. However, if the size of the defect becomes small, it becomes difficult to detect it visually. Further, in the case of the surface treatment by friction stirring as in this embodiment, burrs are generated on the surface of the work, so that it becomes more difficult to visually detect a defect in a portion covered with burrs.

Therefore, in the present embodiment, during the surface treatment by friction stirring, the power waveform of the spindle of the machine tool is monitored using a power meter, a frequency measuring instrument, etc., and the rotary tool is applied to the work surface by a computing device such as a personal computer. The amount of power consumed until the workpiece comes into contact with the workpiece and is pulled out from the workpiece surface is calculated, or the workpiece surface temperature before the surface treatment is started is measured in advance by a temperature sensor or the like.

Immediately after the processing, the relationship between the work temperature and the power consumption is analyzed using a personal computer or the like, and when the power consumption shows an abnormally high value, it is considered that a defect has occurred and a warning is issued.

Specifically, a predetermined size (for example, length 15
Using an aluminum alloy casting (0 mm × width 35 mm × thickness 20 mm) as a work, the rotary tool is attached to the spindle of the NC machine tool, and the movement trajectory of the rotary tool with respect to the work surface is 100 mm. Surface treatment by friction stirring is performed according to the treatment conditions shown in.

Further, when the processing is continuously performed under the above conditions,
Since the frictional heat generated is transmitted to the jig holding the work and the heat of the jig is conducted to the next work, the surface temperature of the work just before the start of the surface treatment is measured with a contact thermometer or the like.

Further, a power meter is attached to the power supply line to the spindle motor and the measured value is transferred to a personal computer, whereby the spindle power waveform shown in FIG. 22 is obtained.
Further, the power consumption amount when the spindle is idling (no load) is calculated in advance, and the spindle power waveform required for the surface treatment is calculated by integrating the spindle power waveform using the value as a reference value.

FIG. 23 shows the relationship between the measured value of the work surface temperature and the power consumption of the spindle before the start of the surface treatment for each work. When the defects in the surface modification region are visually inspected, 62. A defect was recognized in the work corresponding to the position of 2 ° C-113.18 KWs.

Therefore, the above visual inspection results and FIG.
When it is confirmed whether there is a correlation with the results shown in Fig.
As shown in FIG. 4, there is a high correlation with the measurement result of the work in which the power consumption is higher than the work surface temperature.

Therefore, each measured value of the work temperature and the power consumption exceeds the predetermined threshold value by using the substantially linear correlation between the work temperature and the spindle power consumption of FIG. In this case, it is possible to save man-hours by visual inspection by assuming that the work in the corresponding process has a defect and issuing a warning, and judge the quality of the work by remote control online on the assembly line. You can do it.

[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 diagram showing a component ratio of the aluminum alloy of this embodiment.

5A is a diagram showing a processing depth according to a tip pin length, FIG. 5B is a diagram showing a tip pin length PL, and FIG. 5C is a diagram showing a maximum processing depth Dmax.

FIG. 6 is a diagram showing a processing depth according to a rotation speed and a feed speed of a pin-shaped tool.

FIG. 7 is a diagram showing a basic shape near a port of a cylinder head material for a diesel engine before finishing, which is subjected to surface treatment by friction stirring according to the present embodiment.

8 is a cross-sectional view taken along the line I-I of FIG. 7.

FIG. 9 is a diagram showing a characteristic shape near a port of a cylinder head material for a diesel engine before finishing, which is subjected to a surface treatment by friction stirring according to the present embodiment.

10 is a cross-sectional view taken along the line II-II of FIG.

FIG. 11 is a flowchart illustrating a manufacturing process of the cylinder head for a diesel engine of the present embodiment.

FIG. 12 is a cross-sectional view of an intervalve portion showing a surface treatment example of the present embodiment.

FIG. 13 is a sectional view of an intervalve portion showing a comparative example with respect to the surface treatment of the present embodiment.

FIG. 14 is a diagram illustrating a surface treatment of a cylinder head of an in-line multi-cylinder diesel engine using the friction stir treatment of the present embodiment.

FIG. 15 is a schematic front view of a machine tool as a tool driving unit.

FIG. 16 is a diagram illustrating a first processing example of surface processing by a tool changer.

FIG. 17 is a diagram illustrating a second processing example of surface processing by a tool changer.

FIG. 18 is a view showing a temporal comparison of tool temperature and processing depth in the first processing example and the second processing example.

FIG. 19 is a diagram showing a temperature measurement portion and a position measurement portion of the rotary tool.

FIG. 20 is a diagram showing tool position measurement data based on the surface temperature and thermal expansion of a tool when 10 workpieces are continuously processed by one rotary tool.

FIG. 21 is a diagram showing a surface treatment condition by friction stirring.

FIG. 22 is a diagram showing a spindle power waveform during surface treatment by friction stirring.

FIG. 23 is a diagram showing the result of visual inspection of defects after friction stir processing.

FIG. 24 is a diagram showing a correlation between a work temperature immediately before friction stir processing and an integral value of a spindle power waveform.

[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 16 valve area 17,18 beams H cylinder head material

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) // B23K 20/12 310 B23K 20/12 310

Claims (4)

[Claims] 1. A rotary tool, which is detachably supported by a tool support means of a machine tool, is inserted into the surface of a work, and the work surface is agitated without being melted by frictional heat generated by the rotation of the rotary tool to modify the work. In the surface treatment method, the surface treatment area of the work is stirred by the rotary tool, the rotary tool is changed to a burr removal tool for removing burrs of the work, and the surface treatment area is changed by the burr removal tool. A surface treatment method comprising treating the surface. 2. The surface treatment method according to claim 1, further comprising a plurality of the rotary tools, and selecting a rotary tool different from the rotary tool used immediately before after the treatment with the deburring tool. 3. A rotary tool, which is detachably supported by a tool support means of a machine tool, is inserted into a work surface, and the work surface is agitated without being melted by frictional heat generated by the rotation of the rotary tool to modify the work surface. Which is a surface treatment apparatus, wherein the surface treatment area of the work is agitated by the rotary tool, a rotary tool driving means, a tool changing means for changing the rotary tool to a burr removal tool for removing a burr of the work, The tool driving means comprises a deburring tool driving means for processing the surface treatment area with the deburring tool. 4. A rotary tool, which is detachably supported by a tool support means of a machine tool, is inserted into the surface of a member, and the frictional heat generated by the rotation of the rotary tool is agitated without melting the surface of the member for modification. A member which has been subjected to a surface treatment, wherein the surface treatment area of the member is agitated by the rotary tool, and a burr removal tool for removing burr in the surface treatment area after friction agitation by the rotary tool. And a burr removing section which is processed by changing the above.