JP4370119B2 - Friction stir welding equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus that takes measures against heat of a rotary tool in friction stir welding, and more particularly, to a friction stir welding apparatus that can eliminate the thermal effect on a rotary tool during friction stir welding.
[0002]
[Prior art]
For example, Japanese Patent Application Laid-Open No. 7-505090 (Patent Document 1) discloses a novel method for joining long materials as a solid-phase joining method by friction stirring, which is substantially more effective than a workpiece. By inserting a rotating tool made of a hard material into the joint of the workpiece and moving it while rotating the rotating tool, plastic flow due to frictional heat generated between the rotating tool and the workpiece is caused. In the joining method for joining workpieces, such a friction joining method is capable of joining a joining member in a solid phase state while integrating a softened solid phase portion that is moved while rotating a rotary tool. There is an advantage that even a long material that has no distortion and is infinitely long in the joining direction can be continuously solid-phase joined in the longitudinal direction. Further, since the solid-phase bonding using the plastic flow of the metal by the frictional heat between the rotating tool and the bonding member, the bonding can be performed without melting. Further, since the heating temperature is low, deformation after joining is small. Since the joint is not melted, there are many advantages such as fewer defects.
[0003]
Next, a rotary tool used for friction stir welding will be described. As disclosed in Japanese Patent Publication No. 7-505090, friction stir welding includes a probe type and bobbin tool type rotary tool, and a probe type tool 20 includes a shoulder 21 and a shoulder 21 as shown in FIG. The shoulder 21 has a circular shoulder surface. Then, the probe type tool 20 is rotated from the surface of the joining line in a state where a plurality of mold materials are abutted or fitted, and the probe 22 is inserted into a hole (not shown) provided in the joining line of the workpiece. In addition, frictional heat is applied to the workpiece by the shoulder portion 21 slidably rotating on the joining lines of the plurality of mold materials, and the periphery of the probe 22 is plastically fluidized. In this state, the probe tool 20 is moved along the joining line. As a result, the surroundings of the joining line are plastically fluidized, and the two materials are stirred and kneaded along the joining line while receiving pressure, and move to the rear side of the probe. As a result, the plastic flowed material loses frictional heat on the rear side and rapidly cools and solidifies, so that both panel plates are joined together with the materials mixed together.
[0004]
The rotary tool is generally fixed to a machine spindle through a milling chuck (hereinafter referred to as a holder) used during end milling of a machine tool, and is rotated by receiving a rotational driving force from the machine spindle. Unlike a normal machine tool, the tool is not cooled by the coolant, but receives frictional heat input of 450 to 560 ° C., so that the holder is tempered, the strength is reduced, and the tool is joined as it is. If the work is continued, the holder may be cracked, distorted or even damaged.
[0005]
For this reason, the rotary tool is cooled in the prior art. The friction stir welding apparatus used for the friction stir welding is cooled for friction welding as disclosed in JP-A-10-52770 (Patent Document 2) and JP-A-11-10367 (Patent Document 3). Cool the rotary tool by circulating a coolant through the rotary tool, or spray the coolant on the outer surface of the rotary tool near the lower end or near the lower end of the rotary tool for friction stir welding. I was going. In addition, as disclosed in Japanese Patent Laid-Open No. 10-52770 (Patent Document 3), the cooling of the workpiece joint is performed not only on the lower end of the rotary tool but also on the upper surface of the joint of the workpiece. It was done by spraying on.
[0006]
However, if only the lower end of the rotary tool and the vicinity of the lower end are cooled, the life of the rotary tool itself can be extended. However, since the spindle that holds the rotary tool is not cooled, the heat generated by friction stir welding is reduced. In some cases, the bearing is transmitted to the spindle via the rotary tool and the bearing which rotatably supports the spindle is deteriorated. In addition, during friction stir welding, the temperature of the joined portion of the material to be joined rises significantly, so the temperature of the material to be joined becomes high and a temperature distribution occurs, which causes distortion of the joined material to be joined. There was sometimes. This phenomenon is particularly noticeable when the material to be joined is a thin and long member. Further, when water or the like is sprayed on the joint portion of the material to be joined, the joint portion may be corroded.
[0007]
In order to solve such a problem, in Japanese Patent Application Laid-Open No. 2001-204559 (Patent Document 4), a spindle cooling mechanism for cooling a spindle that supports a rotary tool that frictionally stir welds a material to be joined at one end is provided. Has proposed a technology comprising a refrigerant supply port that passes through the housing and supplies a refrigerant between the housing and the spindle and a refrigerant discharge port that discharges the refrigerant.
Further, the conventional technology supports a backing jig that receives the reaction force of the rotating tool of the joining member on the base, and has a refrigerant flow passage inside the base, and supplies the refrigerant to the refrigerant flow passage. And a refrigerant discharge means for discharging the refrigerant from the refrigerant flow passage.
[0008]
[Patent Document 1]
Japanese Patent Publication No. 7-505090 [Patent Document 2]
Japanese Patent Laid-Open No. 10-52770 [Patent Document 3]
JP 11-10367 A [Patent Document 4]
JP 2001-204559 A
[0009]
[Problems to be solved by the invention]
However, in the above prior art, cooling by the refrigerant passage built in the base with the backing member that contacts the back surface of the joining member means that the cooling heat is joined when the joining member is a thin plate like a single skin. Propagating to the frictional heat input surface of the member surface, and as a result, extra frictional heat input must be performed on the rotary tool side, resulting in an increase in the load on the rotary tool and an increase in the size of the drive source.
[0010]
In view of such a problem, the present invention does not unnecessarily cool the friction stir welding tool or its heat input surface in any case of a probe type or bobbin type tool, and also has good strength and strength of the rotary tool and holder. The purpose is to maintain the joining surface and maximize the joining ability of the tool.
[0011]
[Means for Solving the Problems]
The present invention relates to a friction stir welding tool including a pin that enters a joint portion of a workpiece, and a shoulder that is pressed against the joint surface of the workpiece, a holder that holds the friction stir welding tool, and the friction stirrer through the holder. In a friction stir welding apparatus comprising a machine main shaft to which a welding tool is connected,
The holder is formed of steel tempered at a temperature of 560 ° C. to 700 ° C. that is equal to or higher than the temperature range in which the workpiece can be plastically flowed, and the machine spindle is at a temperature that is lower than the temperature range in which the workpiece can be plastically flowed. It is characterized by being formed of steel tempered in.
In this case, the mechanical spindle is formed of steel tempered at a temperature lower than the temperature range in which the workpiece can be plastically flowed, specifically, steel tempered at a temperature of 250 ° C. or lower. Good.
A cooling means for maintaining the temperature of the mechanical spindle at a temperature of 250 ° C. or less may be provided between the holder and the mechanical spindle.
Specifically, the cooling means includes a hole provided in the machine main shaft, a shank for attaching the holder to the hole, and a refrigerant passage provided on the surface of the shank. the holder may be conductively constituting a cooling fluid to the refrigerant passage from the machine spindle side for supporting the, also the cooling fluid inlet passage provided in the shank portion a lower position of the holder, the shank portion than the rotation Engineering tool side You may comprise so that a cooling fluid can be conducted toward the side.
Furthermore, it is preferable that the discharge port of the cooling passage formed on the surface of the shank portion is formed in a gap between the holder flange portion located on the lower surface of the shank portion and the bottom surface of the machine spindle.
Specifically, the present invention is a steel in which the steel is tempered at a temperature between 560 ° C. and 700 ° C. when the workpiece is aluminum or aluminum alloy steel, for example, alloy tool steel, The main shaft is formed of steel tempered at a temperature of 250 ° C. or less, and a cooling means is interposed between the holder and the machine main shaft to maintain the machine main shaft side at a temperature of 250 ° C. or less, preferably 150 ° C. or less. Features.
[0012]
According to this invention, for example, the melting point of aluminum softened by friction stir welding is 660 ° C. Therefore, the softening temperature in the case of a joining material made of such an aluminum material is around 450 ° C., and the temperature range in which plastic flow is possible is It becomes 450 degreeC-560 degreeC which is more than the said softening temperature and is significantly lower than melting | fusing point. Therefore, the tempering temperature of the tool steel should be set to be higher than this temperature and lower than the quenching temperature. Specifically, the alloy tool steel should be tempered at a temperature between 560 ° C. and 700 ° C. .
However, since the alloy tool steel is hard, if it is composed of the alloy tool steel up to the machine spindle side, not only the cost of the material but also the time and cost for the cutting work are required.
Therefore, the present invention is such that the machine spindle side is formed of steel that is tempered at a temperature of 250 ° C. or less, and the machine spindle side between the holder and the machine spindle is 250 ° C. or less, preferably 150 ° C. or less. By interposing a cooling means to maintain and preventing heat propagation to the machine spindle side, the machine spindle can be used with existing ones, not only making special spindles unnecessary, but also reducing material costs etc. .
And in order to use the existing main spindle, it is not preferable that machining to the main spindle side requires a special main spindle.
[0013]
Therefore, the present invention provides a coolant passage on the surface of the shank portion of the holder that attaches the holder to the machine spindle hole, and prevents heat transfer from the rotary tool to the machine spindle side through the holder by the cooling fluid that conducts the coolant passage. It is configured as follows.
[0014]
In this case, if a system is adopted in which the cooling fluid can be conducted to the refrigerant passage from the side of the machine spindle supporting the holder, the cooling fluid can be easily introduced, and the cooling fluid is placed below the shank portion of the holder. the introduction passage is provided, if conductively constituting the cooling fluid from the rotating Engineering tool side toward the shank side, will be cooled the most exothermic high rotational engineering tool side, it enhances the thermal shielding effect.
[0015]
According to this invention, it is preferable that the passage of the cooling fluid is formed such that a groove is formed in a spline shape on the surface of the tapered shank of the holder and the cooling fluid is passed through the groove.
That is, if a groove is formed on the tool holder mounting surface of the machine spindle, in the case of an existing machine tool in the factory, modification of the holder mounting surface occurs, which is troublesome, but if a groove is formed on the taper shank surface of the holder, It is preferable because reworking on the machine tool side (grooving of the holder mounting surface) is unnecessary.
[0016]
Further, according to the present invention, a cooling passage is formed around the surface of the taper shank facing the holder housing hole of the machine spindle, and the flow direction of the refrigerant set by the cooling passage is upward from the holder housing hole. That is, when the coolant is flowed in a direction away from the rotary tool that generates frictional heat, the cooling heat is slowly propagated on the rotary tool side, and the effect of indirect cooling via the holder is further enhanced.
That is, when a refrigerant is passed through a rotary tool that is frictionally input as in the prior art, the cooling heat of the refrigerant propagates to the frictional heat input surface of the joining member surface, and as a result, excess frictional heat input is performed on the rotary tool side. It is necessary to increase the load of the rotary tool and increase the size of the drive source.
In contrast so as to face the large holder heat capacity in the present invention, moreover, by flowing a cooling heat refrigerant in the direction away from the rotating tool toward the rotation Engineering tool side to said shank portion, but the heat capacity is small frictional heat input temperature Heat can be cut off between the high rotating tool side and the machine spindle through the holder, between the rotating tool side in the temperature range of approximately 450 ° C or higher and the spindle side made of steel with a low tempering temperature. The heat can be cut off without causing unnecessary heat transfer. Therefore, temper softening on the main shaft side does not occur.
[0017]
Furthermore, since the discharge port of the cooling passage formed on the surface of the shank portion is formed in the gap between the holder flange portion located on the lower surface of the shank portion and the bottom surface of the machine spindle, further heat insulation can be achieved.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the embodiments shown in the drawings. However, unless otherwise specified, the dimensions, shapes, relative arrangements, and the like of the components described in this embodiment are merely illustrative examples and not intended to limit the scope of the present invention.
[0019]
1 and 2 are schematic views showing a schematic configuration of a friction stir welding apparatus according to first and second embodiments of the present invention, and FIG. 3 is a cross-sectional view taken along lines AA and BB in FIGS. It is.
In the figure, reference numeral 3 denotes a work to be joined, for example, a structure in which single skin panels are brought into contact with each other.
As shown in FIG. 4, the probe-type tool 20 is a probe-type rotary tool in which a probe 22 projects from the central axis of a cylindrical shoulder 21. The probe 20 is chucked by the holder 1, and the tapered shank 11 of the holder is used. Is attached to the tapered holder hole 31 of the main shaft 2.
A surface plate 4 is located on the back side of the work 3, and the work 3 is fixed in position by the surface plate 4.
[0020]
The main shaft 2 includes a main shaft main body 30 that is rotationally driven by the rotational force transmitted from the main shaft gear 32, and a pair of main shaft bearings 40 and 50 that rotatably support the main shaft main body 30 by bearings 60.
The lower spindle bearing 40 facing the holder hole 31 is provided with a spiral ring-shaped refrigerant passage 43 on the circumferential surface between the bearing inner cylinder 41 and the outer cylinder 42, and on the lower end side of the refrigerant passage 43. The refrigerant introduction port 44 is provided with a refrigerant discharge port 45 on the upper end side, and the refrigerant passage 43 is set so that the flow direction of the refrigerant is an upward flow from the holder hole 31 upward.
Further, the refrigerant introduction port 44 is provided in the middle of the holder hole 31, the refrigerant discharge port 45 is located above the holder hole 31, and the refrigerant passage 43 is located from the probe hole 20 in the middle of the holder hole 31. Form in a direction away from you.
The upper main shaft bearing 50 located above the main shaft gear 32 also has a refrigerant passage 51. However, the refrigerant passage 51 is a simple ring and does not have a cooling heat gradient. Mineral oil cooled with a coolant is used as the refrigerant.
[0021]
The holder 1 is fitted into a taper holder hole 31 of the main shaft 2 and includes a taper shank 11 that rotates and rotates as a unit, and a chucking portion 12 that grips the probe-type tool 20 by chucking.
[0022]
The mechanical spindle 50 is made of steel tempered at 1150 ° C. using steel tempered at a temperature of 250 ° C. or lower, for example, chromium molybdenum steel (SCM415), and then tempered at 150 ° C. to 200 ° C. .
[0023]
Then, a cooling medium such as air or liquid nitrogen is passed through the holder 1 so that the mechanical spindle 50 side is maintained on the surface of the holder 1 at a temperature of 250 ° C. or lower, preferably 150 ° C. or lower, and a discharge port. 72 is provided.
Specifically, a coolant passage 71 is provided on the surface of the holder shank portion 100 for attaching the holder 1 to the holder attachment hole 31A of the machine spindle 50. Specifically, the passage 71 for a cooling medium such as air is provided in the taper shank 100 of the holder. Eight spline-shaped grooves (grooves along the axial direction) are formed on the surface, and the cooling medium is configured to pass through the grooves of the refrigerant passage 71, and the refrigerant of the refrigerant passage 71 formed on the surface of the shank portion 100. A discharge port 72 is formed in a ring-shaped gap 72 between the holder flange portion 102 located on the lower surface of the shank portion 100 and the machine spindle bottom surface 59. As a result, it is possible to prevent the heat transfer from the probe-type tool 20 to the machine spindle 50 side via the holder 1 by the cooling fluid conducted through the refrigerant passage 71 to the refrigerant discharge port 72.
[0024]
FIG. 1 shows that the refrigerant introduction passage 58 provided on the central axis of the machine spindle is connected to the introduction passage 73 on the central axis of the taper shank 100, and in the middle of the passage, the refrigerant passage has a spline groove shape on the surface of the shank. The cooling medium is guided to the refrigerant passage 71 through the communication holes 74 that radiate outwardly, and is configured to be able to be released to the atmosphere from the ring-shaped gap 72 while cooling the holder 1.
[0025]
According to this embodiment, since the cooling fluid can be conducted to the refrigerant passages 58 and 71 to 74 from the machine main shaft side 50 supporting the holder 1, the introduction of the cooling fluid is facilitated.
[0026]
FIG. 2 shows a configuration in which a coolant introduction passage 75 is provided at a position below the shank portion 100 of the holder so that a cooling fluid (refrigerant) can be conducted from the proximity side of the rotary tool 21 to the shank portion 100 side. A refrigerant introduction passage 75 is provided in the vicinity of the chuck position, and is connected to the introduction passage 73 on the central axis of the taper shank 100, and spreads radially toward the spline groove-like refrigerant passage 71 on the surface of the shank portion 100 at an intermediate position. A cooling medium is guided to the refrigerant passage 71 through the communication hole 74 and can be discharged to the atmosphere from a ring-shaped gap (refrigerant discharge port) 72 while cooling the holder 1.
According to this embodiment, if the coolant introduction passage 75 is provided in the lower position of the shank portion of the holder 1 and the cooling fluid can be conducted from the proximity side of the rotary tool 21 toward the shank portion 100, the heat generation is highest. The probe-type tool 20 side is cooled, and the heat blocking effect is enhanced.
[0027]
Next, the holder 1 is
What was tempered at 150 to 200 ° C. after being quenched at 1150 ° C. using chromium molybdenum steel (SCM415) (Comparative Example 1),
What was tempered at 150 to 200 ° C. after being quenched at 1150 ° C. using nickel chromium molybdenum steel (SNCM420) (Comparative Example 2),
Furthermore, after quenching at 1150 ° C. using alloy tool steel (SKD61), tempering at 560 ° C. to 650 ° C. ( Example 1 ),
Further, the alloy tool steel (SKD6) was tempered at 1150 ° C. and then tempered at 560 ° C. to 650 ° C. (Example 2)
The four types of holders
A cooling medium such as air or liquid nitrogen is conducted to the refrigerant passage 71 and the discharge port 72 of the holder 1 so that the temperature of the holder mounting hole 31A on the side of the mechanical spindle 50 facing the holder 1 is 150 ° C. or less. While maintaining the tempering temperature, the moving feed speed of the friction stir welding probe, 0.05 to 2 m / min, and the rotation speed are appropriately selected within the range of 500 rpm to 15000 rpm, while the aluminum or aluminum alloy of the workpiece is selected. Friction stir welding was repeated over 500 m to 1000 m while frictional heat of 450 ° C. to 560 ° C. was applied to the joining surfaces of the steel.
As a result, it was confirmed that the holder 1 of the comparative example was deteriorated in strength, whereas the holder 1 and the mechanical spindle of the example were not deteriorated in strength.
[0028]
【The invention's effect】
As described above, according to the present invention, the friction stir welding tool and its heat input surface are not unnecessarily cooled, and the strength of the rotary tool and the holder and the good joining surface are maintained and the joining ability of the tool is improved. I can show it to the maximum.
[Brief description of the drawings]
FIG. 1 is a schematic view showing the overall configuration of a friction welding apparatus according to a first embodiment of the present invention.
FIG. 2 is a schematic view showing an overall configuration of a friction welding apparatus according to a second embodiment of the present invention.
3 is a cross-sectional view taken along lines AA and BB in FIGS. 1 and 2. FIG.
FIG. 4 is a basic configuration diagram of a probe-type rotary tool for friction stir welding according to a conventional technique.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Holder 2 Spindle 3 Workpiece 4 Surface plate 20 Rotating tool 43 Refrigerant passage 44 Refrigerant introduction port 45 Refrigerant discharge port 31 Holder hole 71 Refrigerant passage 72 Refrigerant discharge port

Claims (7)

A friction stir welding tool having a pin that enters the workpiece joint and a shoulder that press-contacts the workpiece joining surface, a holder that holds the friction stir welding tool, and the friction stir welding tool via the holder In a friction stir welding apparatus provided with a coupled mechanical spindle,
The holder is formed of steel tempered at a temperature of 560 ° C. to 700 ° C. that is equal to or higher than the temperature range in which the workpiece can be plastically flowed, and the machine spindle is at a temperature that is lower than the temperature range in which the workpiece can be plastically flowed. A friction stir welding apparatus characterized by being formed of steel tempered in step (b). The friction stir welding apparatus according to claim 1 , wherein the mechanical spindle is formed of steel tempered at a temperature of 250 ° C. or less. 3. The friction stir welding according to claim 1, further comprising a cooling unit that maintains a temperature of the machine spindle at a temperature of 250 ° C. or less between the holder and the machine spindle. 4. apparatus. It said cooling means comprises a hole provided in the machine main shaft, according to claim 3, a shank for mounting the holder to the bore, and a coolant passage provided in the surface of the shank, comprising the Friction stir welding equipment. 5. The friction stir welding apparatus according to claim 4, wherein a cooling fluid can be conducted to the refrigerant passage from a machine main shaft side supporting a holder. A cooling fluid inlet passage provided in the shank portion a lower position of the holder, the friction stir welding apparatus according to claim 4, characterized in that conductively constituting a cooling fluid toward the shank portion than the rotation Engineering tool side. Outlet of the cooling passage formed in the shank portion surface, claim 4 and 5, characterized in that it is formed in the gap between the holder flange and the machine spindle bottom located shank lower surface, or 6, wherein Friction stir welding equipment.

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