Friction stir welding method and apparatus

A friction stir welding (FSW) method and apparatus are provided by which power needed for FSW is reduced and a compact FSW tool can be used. In the FSW method, metal members are lapped one on another and a rotating probe of an FSW tool is inserted into a contact portion of the metal members. The contact portion is softened by frictional heat and stirred by the probe so that the metal members are welded together. A portion of the metal members surrounding the probe is heated by a heater.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a friction stir welding method and an apparatus by which a conductive material, such as aluminum (including aluminum alloy) or the like, and other magnetic materials are welded by friction stir welding (hereinafter friction stir welding is referred to as “FSW”).

2. Description of Related Art

In every case of a conventional FSW method, frictional heat is made use of by a FSW tool comprising a probe and a shoulder portion. The probe is inserted into a weld portion to be welded by FSW and the shoulder portion is urged against members to be welded, such as metal members, (hereinafter referred to as “weld object members”), while the FSW tool is rotated. For this reason, the FSW tool is needed to have a strong rigidity so as to withstand the urging force. Also, a large amount of power is needed so that the FSW tool is forcibly rotated so as to maintain the friction.

Moreover, with respect to the weld object members, a reinforcing means is needed in order for the weld object members to be supported against the urging force of the FSW tool.

Also, in order to obtain a desired frictional heat, a diameter of the probe is sometimes needed to be made larger than a size needed for stirring the weld object members. If weld object members, such as hollow members, have a bone member therein for reinforcement under the weld portion, there is a restriction that a thickness of the bone member must be made larger than the diameter of the probe. That is, there is a problem that the bone member must be selected corresponding to the diameter of the probe.

Likewise, if an integrated piping plate is to be manufactured by FSW, since the distance between adjacent fluid passage grooves of the integrated piping plate cannot be smaller than the diameter of the probe, the degree of the integration is restricted by the diameter of the probe.

Also, there is a restriction of the welding speed due to the welding speed being decided by the time needed for sufficient frictional heat to be generated by the FSW tool.

Also, there is a conventional FSW method in which an additional heating source other than the frictional heat generated by the FSW tool is provided at and around the weld portion to thereby enhance the welding speed. For example, as shown by perspective views ofFIGS. 10,11and12, a rotating probe53is inserted into a weld portion54between weld object members50,51, both made of aluminum, and a contact portion of the weld object members50,51making contact with the probe53is softened by the frictional heat and stirred by the probe53. In this state, a FSW tool52together with the probe53is moved along the weld portion54so that the weld object members50,51are welded together, wherein a front portion of the weld portion54in a moving direction X of the probe53is heated by an outside heating source (laser beam55inFIG. 10, gas flame56inFIG. 11and a heating roller57inFIG. 12) so that the temperature there becomes 100 to 300° C. This is proposed in Patent Document 1 mentioned below.

Also, as shown by a perspective view ofFIG. 13, a heating device comprises an FSW tool having a probe53that moves on a weld portion54of weld object members50,51. Induction heating sources58,59are arranged at front and rear positions of the probe53so as to move together with the probe53. A power source60is used for supplying the induction heating sources58,59with electric power and a temperature setting means61is used for setting a temperature of the weld portion54. A gap is provided between the induction heating sources58,59and the weld object members50,51. At the time of welding, the induction heating sources58,59are heated by the power source60to a set temperature set by the temperature setting means61, so that front and rear portions of the weld portion54in the moving direction X of the probe53are heated by the induction heating sources58,59. This is proposed in Patent Document 2 mentioned next.(Patent Document 1) Japanese published patent 3081808 (FIGS. 1, 2 and 3)(Patent Document 2) Japanese laid-open patent application 2003-94175 (FIG. 1)

Nevertheless, the methods of the above-mentioned Patent Documents 1 and 2 are only provided to show that the pre-heating is done for shortening the treatment time of the FSW method and that post heating is done for enhancing the quality after the treatment. The methods of Documents 1 and 2 have several disadvantages. Specifically, the places to be heated are distant from the place where the FSW is being carried out, thus making it difficult to effectively control the degree of heating and softening of the place where the FSW is being carried out. Also, a large amount of power (electric power) is needed for driving the FSW tool, and a larger FSW tool than is necessary must be used.

SUMMARY OF THE INVENTION

It is an object of the present invention to solve the problems of the prior art by providing a FSW method and apparatus in which the power needed for performing the FSW can be reduced and a FSW tool having a compact size can be used.

In order to achieve the above-mentioned object, the present invention employs the following aspects (1) to (13) in a FSW method and apparatus:

(1) In the first aspect of the present invention, a friction stir welding (FSW) method comprises the steps of lapping metal members one on another and inserting a rotating probe of a FSW tool into a contact portion of the metal members. The contact portion thus makes contact with the probe, thereby causing the contact portion to be softened by frictional heat and stirred by the probe, such that the metal members are welded together. A portion of the metal members surrounding the probe is also heated by a heating means.

(2) In a second aspect of the present invention, the probe and the rotator of the FSW tool are made of a non-conductive material, and the heating means effects an electromagnetic induction heating.

(3) In a third aspect of the present invention, the heating means is provided concentrically with the FSW tool and an electromagnetic wave shielding means is arranged above the heating means.

(4) In a fourth aspect of the present invention, a temperature measuring means measuring a heating temperature of the metal members is provided in the vicinity of the FSW tool, and an output of the heating means is controlled based on a measured value of the heating temperature.

(5) In a fifth aspect of the present invention, a rotational state of the probe is measured, and an output of the heating means is controlled based on the rotational state.

(6) In a sixth aspect of the present invention, a distance between the heating means and a surface of the metal members is adjustable.

(7) In a seventh aspect of the present invention, the heating means is provided concentrically with the FSW tool, and the heating means is pressed against the metal members by a pressing means.

(8) In an eighth aspect of the present invention, the heating means is provided at a front position of the probe in a moving direction of the probe and an inspection of a portion welded by the FSW tool is carried out at a rear position of the probe in the moving direction of the probe is carried out.

(9) In a ninth aspect of the present invention, a plurality of pressing means are arranged around the FSW tool.

(10) In a tenth aspect of the present invention, the heating meansis revolved via a revolving stand while it is moved in the moving direction of the probe.

(11) In an eleventh aspect of the present invention, a FSW apparatus effects FSW of metal members lapped one on another. The FSW apparatus comprises an FSW tool having a probe and a rotator, both being made of a non-conductive material. An electromagnetic induction heating means is provided in the vicinity of, and concentrically with, the FSW tool, and an electromagnetic wave shielding means is provided above the electromagnetic induction heating means.

(12) In a twelfth aspect of the present invention, the FSW apparatus also includes a temperature measuring means provided in the vicinity of the FSW tool, and a temperature setting means for setting a predetermined temperature. A comparing means is provided for computing the difference between the temperature measured by the temperature measuring means and the temperature set by the temperature setting means. A power supply means is provided for controlling a supply current or a supply power to be supplied the electromagnetic induction heating means based on the result computed by the comparing means.

(13) In a thirteenth aspect of the present invention, the FSW apparatus further includes a probe rotational state measuring means for measuring a rotational state of the probe, and a power supply means for enlarging a supply current or a supply power to be supplied to the electromagnetic induction heating means corresponding to the size of a value measured by the probe rotational state measuring means.

The effects of the above-mentioned aspects of the present invention are described as follows:

(1) In the first aspect of the present invention, the portion of the metal members surrounding the probe is heated by a heating means, which enables the contact portion of the metal members to be more efficiently softened by the frictional heat of the rotating probe of the FSW tool, which allows the contact portion to be more efficiently stirred by the probe.

(2) In the second aspect of the present invention, the weld portion to be welded by FSW is heated by electromagnetic induction heating. By the probe and rotator of the FSW tool being made of a non-conductive material, the probe and rotator that rotate at a high speed are not heated by the electromagnetic induction, and strength deterioration caused in, or a thermal influence acting on, an upper drive portion of the FSW tool or other supporting portions can be avoided.

(3) In the third aspect of the present invention, by providing the heating means concentrically with the FSW tool, the weld portion frictionally stirred by the probe can be concentrically heated. Also, even in the case where the welding direction (moving direction of the probe) is curved or in a U-shape, the heating at the weld portion becomes uniform and efficient welding can be carried out.

Further, due to the presence of the electromagnetic wave shielding means, the surrounding metal parts and components are protected from any negative influences, such as heat generation or strain by heat.

(4) In the fourth aspect of the present invention, the heating temperature is measured by the temperature measuring means. By controlling the output of the heating means based on the measured value of the heating temperature, efficient FSW can be carried out.

(5) In the fifth aspect of the present invention, the rotational state of the probe is measured, and by controlling the output of the heating means so as to be increased when the revolution of the probe is decreased or when the current rotating the probe is increased, efficient FSW can be carried out.

(6) In the sixth aspect of the present invention, the heat generation can be adjusted by making the distance between the heating means and the surface of the metal members adjustable.

(7) In the seventh aspect of the present invention, the heating means provided concentrically with the FSW tool is pressed against the metal members by the pressing means and the heat generation due to the frictional heat of the probe can be reduced, thus also reducing the force acting on the FSW tool. As a result, the life of the FSW tool can be elongated and the apparatus can be made smaller.

(8) In the eighth aspect of the present invention, the heating means is provided at the front position of the probe in the moving direction of the probe, and the portion welded by FSW is inspected at the rear position of the probe in the moving direction of the probe. Thus, no excessively large load is needed to act on the probe and shoulder portion so that the size of the FSW tool can be reduced. Also, the work speed can be enhanced so as to contribute to reducing the time needed to perform the welding.

Further, by carrying out the inspection at the same time as the welding work, a work failure can be instantly corrected so that the amount of defects can be reduced and the yield of the products can be remarkably enhanced.

(9) In the ninth aspect of the present invention, the plurality of pressing means are arranged around the FSW tool. This arrangement causes the upper and lower plates to make close contact with each other by an appropriate pressing force. As a result, separation of the upper and lower plates due to vibrations caused by the stirring process can be avoided, and the welding work done by FSW can be ensured.

(10) In the tenth aspect of the present invention, the heating means, while moving in the moving direction of the probe, is revolved via the revolving stand. As a result, even if the welding direction (moving direction of the probe) is curved or in a U-shape, heating of the weld portion becomes uniform and an efficient welding can be carried out.

(11) In the eleventh aspect of the present invention, the probe and rotator of the FSW tool are made of a non-conductive material, and as a result the probe and rotator rotating at a high speed are not heated by the electromagnetic induction. Thus, a strength deterioration of, or a thermal influence acting on, the upper drive portion of the FSW tool or other supporting portions is avoided. Also, by providing the electromagnetic heating means concentrically with the FSW tool, the portion that is welded with FSW by the probe can be concentrically heated. Further, even if the welding direction (moving direction of the probe) is curved or in a U-shape, heating of the weld portion becomes uniform and an efficient welding can be carried out. Also, due to the presence of the electromagnetic wave shielding means, the surrounding metal parts and components are protected from harmful influences, such as heat generation and strain by heat.

(12) In the twelfth aspect of the present invention, the heating temperature is measured by the temperature measuring means, and the output of the electromagnetic induction heating means is controlled based on the measured value of the heating temperature. As a result, efficient FSW can be carried out:

(13) In the thirteenth aspect of the claimed invention, the rotational state of the probe is measured, and by controlling the output of the heating means so as to be increased when the revolution of the probe is decreased or when the current rotating the probe is increased, efficient FSW can be carried out.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Herebelow, embodiments according to the present invention will be described with reference to the appended drawings.

First, an example of a structure of an integrated piping plate that is appropriate to be welded by FSW will be described with reference toFIG. 9.

As shown there, the integrated piping is constructed by an upper plate1and a lower plate2, and a plurality of connectors9or the like of a device, such as a fuel cell power generating system or the like, are arranged on a surface of the upper plate1.

Each of the connectors9is fixed to an integrally formed plate-like unit of the upper and lower plates1,2, welded together by FSW, via a plurality of stud bolts7and nuts8or the like.

A plurality of fluid passages connecting between and among the plurality of connectors9provided on the upper plate1are formed in a weld surface4portion of the lower plate2that is welded to a lower surface of the upper plate1. That is, the lower plate2has its upper surface portion formed with a plurality of fluid passage grooves3(3a,3b) and each of the fluid passages is formed by the upper plate1being lapped on the lower plate2and by peripheral portions of each of the fluid passage grooves3being welded liquid-tight by FSW.

The fluid passages are provided in a form in which they are windingly bent, or a plurality of them are arrayed, or in other forms. Each of the fluid passages is constructed so as to communicate with one or more of the connectors9via respective communication holes6provided in the upper plate1. That is, the fluid passages and the communication holes6function as pipings through which a necessary fluid (liquid or gas) flows into, or flows out of, various devices connected to the integrated piping plate.

Next, a FSW tool of the first embodiment and a FSW method thereof according to the present invention will be described with reference toFIGS. 1,2,3and4.

As shown inFIGS. 1,2and3, a rotator11aof a FSW tool10ato be used for FSW is fixed to a rotating shaft of a rotator drive motor15(FIG. 4) provided on a moving and supporting stand (not shown) to be rotated at a high speed by the rotator drive motor15. The rotator11ais formed having a truncated-conical shape and is provided having its smaller diameter side flat surface arranged downwardly. A flat shoulder portion13is formed on this smaller diameter side flat surface. A probe12aprojects from a central portion of the shoulder portion13to be rotated together with the rotator11a. Also, a ring-like groove14is formed in a surface portion of the shoulder portion13.

It is to be noted that a material of the rotator11aand probe12ais selected from non-conductive materials (ceramics or other non-metals) as it is preferable that no heat is generated by an electromagnetic induction action. By so constructing the rotator11aand probe12aof a non-conductive material, the rotator11aand probe12aare not heated by a heating coil21, to be described later. As a result of the rotator11aand the probe12anot being heated strength deterioration of the rotator11aand probe12ais avoided, and a thermal influence acting on the rotator drive motor15, provided above the FSW tool10a, and the moving and supporting stand can be eliminated.

A heating coil21having a doughnut-like shape as a heater20afor effecting an induction heating is arranged around, and concentrically with, the rotator11awith an appropriate gap maintained between the heating coil21and the rotator11a. This heating coil21is fixed to the moving and supporting stand and is supplied with a high frequency electric power from a heating coil control unit40(FIG. 4) via wiring arranged on the moving and supporting stand.

As the induction heating device including the heating coil21can be employed from those generally obtainable in the market, a detailed description thereof will be omitted, but it is constructed, as shown inFIG. 4, by the heating coil21, a high frequency electric power generator42, a matching section output transformer41, a cooling unit (not shown) cooling the heating coil21, etc.

The heating coil21includes a coil having multiple turns and when the heating coil21is supplied with a high frequency current by the heating coil control unit40, an eddy current is generated in adjacent portions of the upper plate1and lower plate2by the electromagnetic induction action. As a result, the adjacent portions of the upper plate1and lower plate2are rapidly heated by heat generated by eddy current loss and hysteresis loss. A center of this heating is a central portion of the heating coil21, that is, a portion that is being stirred by the probe12a.

It is to be noted that a lower end of the heating coil21is positioned slightly above the level of the shoulder portion13of the rotator11a.

Generally, in the induction heating, the eddy current flows more in the portion near a workpiece surface. Thus, the heat is generated more in the surface portion so that the temperature at the surface of the work piece becomes higher while the temperatures of the inner portions of the workpiece are exponentially lower the further they are from the surface. Hence, in the FSW carried out in the present embodiment, the induction heating is appropriate for heating the weld portion in which the probe12ais inserted.

Also, as shown inFIG. 2, a temperature sensor23(a thermocouple, for example) is arranged in the vicinity of the shoulder portion13. This temperature sensor23also is fitted to the moving and supporting stand.

It is to be noted that the illustration ofFIG. 2shows only one piece of the temperature sensor23arranged in front of the shoulder portion13in the moving direction X of the rotator11a. Nevertheless, as the FSW tool10amoves not only in the moving direction X but also in the reverse direction thereof as well as in the crossing direction thereof, the temperature sensor23may be provided with four pieces, for example, arranged with an equal spacing between each of them in the vicinity of the shoulder portion13.

Moreover, a ring-shaped electromagnetic wave shielding plate22is arranged above the heating coil21with an appropriate gap maintained between the electromagnetic wave shielding plate22and the rotator11a. The electromagnetic wave shielding plate22also is fitted to the moving and supporting stand. It is to be noted that the heating coil21and electromagnetic wave shielding plate22may be fitted to the moving and supporting stand separately from each other or may be first integrated together to then be fitted to the moving and supporting stand.

It is preferable that a radial directional width of the ring-shaped electromagnetic wave shielding plate22is made larger than a radial directional width of the heating coil21. Also, the electromagnetic wave shielding plate22may be shaped so as to cover an upper half portion of the heating coil21.

By so arranging the electromagnetic wave shielding plate22of an appropriate shape around the heating coil21, the surrounding metal parts and components are protected from harmful influences, such as heat generation or strain by heat.

Next, a control of the heating coil21as the heating means20awill be described with reference toFIG. 4.

The rotator drive motor15is supplied with power (or a current) by a FSW tool control unit47. The FSW tool control unit47comprises a power meter (or ammeter) detecting a supply power (or supply current) supplied to the rotator drive motor15.

It is to be noted that, as shown inFIG. 4, the rotator drive motor15driving the rotator11amay comprise a rotational state measuring device or revolution detector16detecting a revolution of the motor15.

Respective signals from the power meter (or ammeter) of the FSW tool control unit47or the revolution detector16and the temperature sensor23arranged around the shoulder portion13are inputted into the heating coil control unit40.

The heating coil control unit40comprises a setting unit43. Before the FSW work is started, preliminary welding is carried out with respect to the upper plate1and lower plate2to be applied with the FSW so that appropriate values of the supply power (or supply current) into the heating coil21and the frequency thereof, the supply power (or supply current) into the rotator drive motor15or the revolution thereof, the moving speed of the FSW tool10aand the temperature around the shoulder portion13can be obtained. These values obtained by the preliminary welding are inputted into the setting unit43to be stored therein as respective predetermined set values. Also, the setting unit43is so constructed that an operation mode, such as a speed-constant control, a weld portion temperature-constant control or the like, can be set therein.

A signal of the measured temperature from the temperature sensor23is inputted into a comparing unit45aprovided in the heating coil control unit40. As the temperature sensor23is usually provided with plural pieces thereof (four pieces, for example), an average value of respective detected values from the plural temperature sensors23is computed or a minimum temperature thereof is selected to be inputted into the comparing unit45a. Also, the comparing unit45ais inputted with a predetermined temperature set value obtained by the preliminary welding and stored in the setting unit43.

The comparing unit45acompares the measured temperature signal with the predetermined temperature set value so that a temperature deviation value is computed to be inputted into a heating coil output computing unit44.

Also, a signal of the supply power (or supply current) into the rotator drive motor15detected by the FSW tool control unit47is inputted into a comparing unit45cprovided in the heating coil control unit40. Also, the comparing unit45cis inputted with a predetermined supply power (or supply current) set value obtained by the preliminary welding and stored in the setting unit43.

The comparing unit45ccompares the measured supply power (or supply current) signal from the FSW tool control unit47with the predetermined supply power (or supply current) set value so that a supply power (or supply current) deviation value is computed to be inputted into the heating coil output computing unit44.

Otherwise, a signal of the revolution of the rotator drive motor15detected by the revolution detector16is inputted into a comparing unit45bprovided in the heating coil control unit40. Also, the comparing unit45bis inputted with a predetermined revolution set value obtained by the preliminary welding and stored in the setting unit43.

The comparing unit45bcompares the measured revolution signal with the predetermined revolution set value so that a revolution deviation value is computed to be inputted into the heating coil output computing unit44.

The heating coil output computing unit44computes a current value to be inputted into the heating coil21based on these inputted values of the temperature deviation value and supply power (or supply current) deviation value or revolution deviation value.

For example, if a rotational resistance of the rotator11ahas been increased by a difference of the material, etc. between the upper plate1and the lower plate2, then, due to the increase of the resistance, the supply power (or supply current) into the rotator drive motor15is increased or the revolution of the rotator11ais decreased.

If the operation mode is of a speed-constant control, in order to maintain the moving speed of the FSW tool10a, it is necessary, for example, to increase the supply current into the heating coil21so that the upper plate1and lower plate2are more heated and softened.

In this case, the heating coil output computing unit44computes a current target value to be inputted into the heating coil21based on the supply power (or supply current) deviation value from the comparing unit45cor the revolution deviation value from the comparing unit45b.

It is to be noted that the temperature deviation value is monitored so as not to exceed a maximum temperature to thereby avoid deterioration of the upper plate1and lower plate2.

The computed current target value is inputted into the high frequency power generator42. The high frequency power generator42controls a firing angle, etc. of a power converter, such as a power transistor, thyristor or the like, based on the current target value. Thereby, the supply power (or supply current) is regulated to be supplied to the heating coil21of the heating means20avia the matching section output transformer41.

Next, if the operation mode is of a weld portion temperature-constant control, the heating coil output computing unit44computes a current target value to be inputted into the heating coil21based on the temperature deviation value so that the temperature deviation value from the comparing unit45abecomes zero.

The computed current target value is inputted into the high frequency power generator42so that the supply power (or supply current) is regulated to be supplied to the heating coil21via the matching section output transformer41.

It is to be noted that in a case where the supply power (or supply current) deviation value from the comparing unit45cor the revolution deviation value from the comparing unit45bincreases, or the supply power (or supply current) increases or the revolution decreases, a moving and supporting stand control unit48controlling movement of the moving and supporting stand is inputted with the supply power (or supply current) deviation value or the revolution deviation value to thereby control the moving speed to be reduced so that the supply power (or supply current) deviation value or the revolution deviation value becomes zero.

Next, by using the apparatus of the first embodiment of the present invention constructed by the FSW tool10a, heater20a, electromagnetic wave shielding plate22, moving and supporting stand and control unit, as mentioned above, a method for working the integrated piping plate comprising the upper and lower plates1,2, as shown inFIG. 9, will be described.

It is to be noted that in the present embodiment, as the heating is done by electromagnetic induction heating, the upper and lower plates1,2are made of a conductive material, such as aluminum, copper, carbon steel or the like, or other magnetic materials.

As shown inFIGS. 1,2and3, the upper plate1is lapped on the lower plate2in which the plurality of fluid passage grooves3are formed in advance. The FSW tool10acomprising the probe12a, etc. is moved in the moving direction X and thereby the weld portion5welded by FSW is formed, wherein the FSW tool10ais moved along entire outer peripheries of the winding fluid passage grooves3. Thus, the weld surface4is formed between the upper and lower plates1,2so that the upper and lower plates1,2are welded to be fixed together in a liquid-tight state.

According to the above-described FSW method and apparatus, induction heating is applied to the upper plate1and lower plate 2 g by the heating coil21. As a result, the heating is done rapidly and without contacting the upper and lower plates1,2. The heating can be applied up to a needed internal depth within the upper and lower plates1,2, and a local plastic fluid area can be easily and efficiently formed.

Also, as the non-contact heater20ais used, no complicated mechanism is needed to follow variations of surface shapes of the workpiece, and the apparatus can be made less expensive and in a simplified manner.

Moreover, if the integrated piping plate is to be worked, as the upper plate1and lower plate2make no contact with each other in the portion of the fluid passage grooves3, the heat can be concentrated on the weld portion to be welded where the upper plate1and lower plate2make contact with each other. Hence, heating of a needed position can be done more efficiently.

Also, as no large pressing force and rotational drive force act on the FSW tool10a, a diameter d2of the shoulder portion13and a diameter d1of the probe12acan be reduced, thereby reducing the entire size of the apparatus. As a result, it becomes possible to manufacture a compact product, such as an integrated piping plate having a high integration degree in which adjacent fluid passage grooves3are more approached each other.

Further, as a heat source needed for FSW relies less on the frictional heat caused by the rotational drive of the FSW tool10a, the welding speed can be elevated to thereby contribute to shortening the work time.

Moreover, as the heater20ais arranged concentrically with the FSW tool10a, even if the welding direction (moving direction of the probe) is bent in a hairpin or U shape, as shown in the example of working the integrated piping plate, heating of the weld portion becomes uniform and an efficient welding becomes possible.

While the above description is made such that the supply power (or supply current) into the heating coil21is controlled based on the temperature detected by the temperature sensor23and the revolution of the rotator drive motor, the supply power into the heating coil21may instead be maintained constant.

In this case, the construction may also be made such that a distance between the heating coil21(and the electromagnetic wave shielding plate22) and the workpiece is adjustable. That is, for example, the heating coil21(and the electromagnetic wave shielding plate22) is connected to the moving and supporting stand via a telescopic joint of which the length is controllable so that the distance from the workpiece can be adjusted.

It is to be noted that while the description of the above embodiment and the function and effect thereof is exemplified by the case of working the integrated piping plate, the present invention is by no means limited thereto but may also be applied to welding of other various products.

Next, a FSW tool of a second embodiment of the present invention and a FSW method thereof will be described with reference toFIGS. 5 and 6.

As shown there, a rotator11bof a FSW tool10bused for FSW is fixed to a rotating shaft of a rotator drive motor15(FIG. 4) provided on a moving and supporting stand (not shown) to be rotated at a high speed by the rotator drive motor15. A lower portion of the rotator11bis formed with a cylindrical shape having a lower flat surface portion. A flat shoulder portion13is formed on this lower flat surface portion.

A probe12bprojects from a central portion of the shoulder portion13to be rotated together with the rotator11b. A material of the rotator11band probe12bis selected from ceramics, hard metals or the like having a high heat resistance and high strength.

A doughnut-shaped heater25constituting a heating means20bfor pre-heating the weld portion5is arranged around, and concentrically with, the rotator11bwith an appropriate gap maintained between the heater25and the rotator11b. A heating element26generating heat by an electric resistance or the like is provided in the heater25.

A material of the heater25is selected from metals or the like having a high heat resistance and high heat conductivity so that heat generated by the heating element26provided in the heater25is efficiently transmitted to the upper and lower plates1,2.

The heater25has an upper surface fixed with a plurality of supporting members27fixed thereon and these supporting members27are fitted to the moving and supporting stand so as to slidably move up and down relative to the moving and supporting stand.

A compression spring28is interposed between the heater25and the moving and supporting stand, and the construction is made such that the heater25moves together with the FSW tool10b, while the heater25makes contact with the upper plate1with an appropriate urging force maintained against the upper plate1by the compression spring28.

Next, by using the apparatus of the second embodiment of the present invention constructed by the FSW tool10b, heater25, etc., as mentioned above, a method for working the integrated piping plate comprising the upper and lower plates1,2, as shown inFIG. 9, will be described.

As shown inFIGS. 5 and 6, the upper plate1is lapped on the lower plate2in which the plurality of fluid passage grooves3are formed in advance so that the FSW is carried out along peripheries of the fluid passage grooves3, as in the first embodiment. The FSW tool10bthat comprises the probe12bintegrally constructed with the shoulder portion13and projecting from the central portion of the shoulder portion13is moved in the moving direction X while the FSW tool10bis driven to rotate in the normal and reverse directions by a drive unit (not shown).

According to the FSW carried out by the FSW tool10band heating means20bof the pre-heating type of the above-described second embodiment, pre-heating is done by the heating means20b. Thereby, heat generation by the frictional heat of the probe12bcan be reduced and a force acting on the FSW tool10bcan also be reduced. Hence, the life of the FSW tool10bcan be elongated and the apparatus can be made smaller. Also, the width of the fluid passage grooves3can be made narrower and the integration degree can be enhanced. Moreover, due to the upper plate1and lower plate2being heated from outside by the pre-heating, the moving speed of the FSW tool10b, that is, the welding speed, can be increased and the efficiency of the work can be enhanced.

Next, a FSW tool of a third embodiment and a FSW method thereof will be described with reference toFIGS. 7 and 8.

As shown there, the upper plate1, lower plate2, fluid passage grooves3and FSW tool10bare the same as those of the second embodiment and description thereof will be omitted.

InFIGS. 7 and 8, a plurality of rollers34are arranged around, and at an appropriate distance away from, the FSW tool10b. Each of the rollers34is rotatably fitted to a pin33that has both its ends fixed to a holder32.

Also, a revolving stand38is revolvably fitted to a moving and supporting stand (not shown). A plurality of struts31is fitted to a lower surface of the revolving stand38so as to slidably move up and down via cylinders or compression springs. The holder32is fixed to a lower (distal) end of each of the struts31. Thus, a pressing device29is constructed by the rollers34, holders32, struts31and revolving stand38. The rollers34constantly press down on the upper plate1with a predetermined pressing force so that the upper plate1makes close contact with the lower plate2.

Further, a heater20cfor heating the weld portion of the upper and lower plates1,2is arranged at a close front position of the FSW tool10bin the moving direction X. This heater20calso is fitted to the revolving stand38via support legs36.

The heater20cmakes no contact with the upper plate1nor with the shoulder portion13and is appropriately selected, for example, from an induction heating device or the like. Nevertheless, it may also be selected from a heater or the like that makes contact with the upper plate1with an appropriate pressing force.

Also, an inspecting device35for inspecting the work quality of the weld portion5welded by FSW is arranged at a rear position of the FSW tool10b. This inspecting device35also is fitted to the revolving stand38.

The inspecting device35may be either of a contact type or a non-contact type and is selected from devices constructed such that signals of an image of a weld portion5surface taken by a CCD camera arranged noncontact-wise are inputted into a control section (not shown), or such that signals of an internal welded state taken by an ultrasonic or X-ray inspecting device provided making contact with the weld portion5are inputted into a control section (not shown).

The control section analyzes these signals and judges whether the welded state of the weld portion5is sufficient or not with respect to the heating state and the revolution and moving speed of the FSW tool10b. This allows the operation conditions of the heating temperature of the weld portion5and the pressure, revolution and moving speed of the FSW tool10b, etc. to be controlled at an optimal state.

By the construction of the heater20c, inspecting device35and pressing device29being fitted to the revolving stand38, when the FSW tool10bmakes linear or winding movements along the weld portion5, these devices can move together with the FSW tool10b.

According to the FSW carried out by the FSW tool10b, heater20cand pressing device29of the above-described third embodiment, no large load acts on the probe12and shoulder portion13and their sizes can be reduced. If an integrated piping plate is to be manufactured, the integration degree can be enhanced and, at the same time, the work speed can be enhanced, thereby contributing to reducing the time required to perform the welding.

Also, by providing the inspecting device, the welding quality can be inspected at the same time. Thereby, a work failure can be instantly corrected so that the amount of defects can be reduced and the yield of the products can be remarkably enhanced.

Moreover, due to the plurality of pressing device29, the portion near the probe12of the upper plate1is pressed down with an appropriate pressing force. Thereby, the upper plate1makes close contact with the lower plate2, and separation of the upper plate1from the lower plate2due to vibrations caused by stirring by the probe12can be prevented so that the welding is ensured.

In the above, while the present invention has been described with respect to the first, second and third embodiments, the present invention is by no means limited thereto, but may be supplemented with various modifications and variations of the concrete structure within the scope of claims of the invention as appended hereto.