Machine tools for friction stir welding

Abstract

The present invention relates to machine tools for friction stir welding, the machine tools comprising: a housing unit; a spindle unit that is provided with a spindle and rotatably disposed inside the housing unit; a bearing unit disposed between the housing unit and the spindle unit in order to support the rotation of the spindle unit; a tool unit that rotates in conjunction with the spindle unit in order to perform friction stir welding on a workpiece; a core flow path unit that extends through a portion of the spindle unit; and a branch flow path unit whereby cooling fluid delivered via the core flow path unit flows to the front end surface of the spindle.

Description

Friction stir welding machine tools

[0001] The present invention relates to a machine tool for friction stir welding, and more particularly, to a machine tool for friction stir welding that can efficiently block heat generated in a tool unit during friction stir welding from being transferred to a spindle unit, thereby improving the friction stir welding speed.

[0002] In general, a machine tool refers to a machine used for the purpose of processing a metal / non-metal workpiece into a desired shape and size using an appropriate tool using various cutting or non-cutting processing methods.

[0003] Various types of machine tools, including turning centers, vertical / horizontal machining centers, gate-type machining centers, Swiss turns, electrical discharge machines, horizontal NC boring machines, CNC lathes, and multi-tasking machines, are widely used in various industrial fields for their respective tasks.

[0004] Among machine tools, a multi-tasking machine (MTM) is a turning center equipped with a multi-functional automatic tool changer (ATC) and a tool magazine, capable of performing a variety of machining operations, including turning, drilling, tapping, and milling. In a multi-tasking machine, the operator manually loads or replaces tools required for machining into the tool magazine.

[0005] Many types of machine tools in use today typically feature control panels utilizing numerical control (NC) or computerized numerical control (CNC) technology. These panels feature various function switches or buttons and a monitor.

[0006] In addition, the machine tool is equipped with a table on which the workpiece material is placed and transferred for processing the workpiece, a pallet for preparing the workpiece before processing, a spindle on which a tool or workpiece is combined and rotates, a tailstock for supporting the workpiece during processing, a vibration damper, etc.

[0007] Typically, in machine tools, the table, tool rest, spindle, tailstock, and oscillation unit are equipped with a transfer unit that moves along the transfer axis to perform various processing operations.

[0008] Additionally, machine tools generally use multiple tools for various processing operations, and tool magazines or turrets are used as tool storage spaces for storing multiple tools.

[0009] These machine tools use multiple tools for various processing tasks, and a tool magazine is used as a tool storage space to store multiple tools.

[0010] Additionally, machine tools are generally equipped with an automatic tool changer (ATC) to retrieve or retract a specific tool from the tool magazine under the command of the numerical control unit in order to improve the productivity of the machine tool.

[0011] Additionally, machine tools are typically equipped with an automatic pallet changer (APC) to minimize downtime. The APC automatically exchanges pallets between the workpiece processing area and the workpiece installation area. Pallets can be loaded with workpieces.

[0012] Additionally, machine tools are generally classified into turning centers and machining centers depending on the processing method.

[0013] Meanwhile, Friction Stir Welding (FSW) refers to a welding process in which a tool having a pressurized portion and pin-shaped projections is inserted into the materials to be joined while rotating at high speed, and heat is generated by the mutual friction between the tool and the materials to be joined. This frictional heat softens the material around the tool, and the materials on both sides of the joining surface are forcibly mixed due to the plastic flow of the material caused by the stirring of the tool.

[0014] The joining materials for friction stir welding (FSW) are mainly lightweight non-ferrous metals (AlM Cu, etc.).

[0015] Friction stir welding (FSW) of this type has the advantage of being a solid-state weld, free of solidification defects (e.g., pores, high-temperature cracks, softening cracks, etc.) and having high joint strength.

[0016] Friction stir welding (FSW) is a forging-type joining process that requires high axial force, frictional heat generated during processing, and vibration caused by the stirring action when the tool rotates.

[0017] Friction stir welding (FSW) with these characteristics can improve welding quality only when the frictional heat between the tool and material is maintained.

[0018] However, in the case of conventional friction stir welding machine tools, when friction heat is maintained between the tool and the material to perform friction stir welding (FSW), the heat generated from the tool is transferred not only to the material but also to the spindle and other parts of the material, causing thermal expansion of the spindle unit and bearing unit.

[0019] In this way, conventional friction stir welding machine tools have problems in which the lifespan of the spindle unit and bearing unit is rapidly reduced or damaged due to thermal expansion of the spindle unit and bearing unit.

[0020] To solve this problem, if cooling fluid is supplied to the center of the tool of a conventional friction stir welding machine tool, the frictional heat between the tool and the material is cooled, which causes another problem in that friction stir welding itself cannot be performed.

[0021] Accordingly, conventional friction stir welding machine tools limit the friction stir welding speed to a level that balances natural cooling by lowering the friction stir welding speed, thereby suppressing the frictional heat between the tool and the workpiece, thereby preventing the heat generated from the tool from being directly transferred to the spindle and other parts of the workpiece. However, this has caused a problem of reduced productivity.

[0022] Another method, conventional friction stir welding machine tools used a method of attaching a separate attachment head between the spindle unit and the tool unit to maintain the frictional heat between the tool and the workpiece, thereby preventing the heat generated from the tool from being transferred to the spindle as well as other parts of the workpiece, while also increasing productivity. However, the additional use of an expensive separate attachment head resulted in an increase in the production cost of the machine tool.

[0023] The present invention is to solve the above problems, and the present invention efficiently blocks heat generated in the tool unit from being transferred to the spindle unit and the bearing unit by transferring the cooling fluid transferred through the core passage part to the front end face of the spindle through the branch passage part, thereby preventing thermal expansion of the spindle unit and the bearing unit, thereby preventing damage to the spindle unit and the bearing unit, and providing a friction stir welding machine tool capable of reducing the production cost of the machine tool and maximizing productivity by cooling the heat of the tool unit without attaching an expensive separate attachment or lowering the friction stir welding speed.

[0024] In order to achieve the object of the present invention, a friction stir welding machine tool according to the present invention may include a housing unit; a spindle unit having a spindle and rotatably disposed within the housing unit; a bearing unit disposed between the housing unit and the spindle unit to support rotation of the spindle unit; a tool unit that rotates in conjunction with the spindle unit to perform friction stir welding on a material; a core passage part formed to extend through a portion of the spindle unit; and a branch passage part that allows cooling fluid transmitted through the core passage part to flow to a front end surface of the spindle.

[0025] In addition, in a preferred embodiment of the friction stir welding machine tool according to the present invention, the machine tool may further include a space section forming a closed circulation space inside by the tool unit and the spindle to allow the cooling fluid transmitted through the core passage section to flow to the branch passage section while the tool unit is coupled to the spindle.

[0026] In addition, in a preferred embodiment of the friction stir welding machine tool according to the present invention, the branch flow path can supply cooling fluid to the front end surface of the spindle where the spindle unit and the tool unit are coupled, thereby blocking heat generated in the tool unit from being transferred to the spindle unit and the bearing unit.

[0027] In addition, in a preferred embodiment of the friction stir welding machine tool according to the present invention, a tool path portion formed to extend inside the tool unit so as to be in communication with at least one of the core path portion and the space portion may be further included.

[0028] In addition, in a preferred embodiment of the friction stir welding machine tool according to the present invention, a front end flow path part may be further included, which is formed axially along the circumferential direction based on the axis center on the front end surface of the spindle so that the cooling fluid transmitted through the branch flow path part flows in the circumferential direction.

[0029] In addition, in a preferred embodiment of the friction stir welding machine tool according to the present invention, a discharge unit may be further included, which is formed to be spaced apart from the branch flow section in the circumferential direction along the tip flow section and discharges the cooling fluid flowing along the tip flow section to the outside of the tip flow section.

[0030] In addition, in a preferred embodiment of the friction stir welding machine tool according to the present invention, the branch flow path may include a first branch flow path formed penetrating the spindle so that one end communicates with the space portion and the other end is adjacent to the bearing unit; and a second branch flow path formed penetrating the spindle so that one end communicates with the first branch flow path and the other end communicates with the tip flow path.

[0031] In addition, in a preferred embodiment of the friction stir welding machine tool according to the present invention, the branch flow portion and the discharge portion may be arranged radially in multiple numbers so as to be spaced apart from each other at a predetermined angle along the circumferential direction based on the axis center.

[0032] In addition, in a preferred embodiment of the friction stir welding machine tool according to the present invention, the discharge portions may be arranged in multiple units spaced apart at a predetermined angle along the circumferential direction with respect to the axis center.

[0033] In addition, in a preferred embodiment of the friction stir welding machine tool according to the present invention, two or more branch flow paths may be arranged so as to be spaced apart at a predetermined angle along the circumferential direction with respect to the axis center between the discharge parts arranged adjacently along the circumferential direction with respect to the axis center.

[0034] In addition, in a preferred embodiment of the friction stir welding machine tool according to the present invention, the spindle unit includes a clamp bar that is axially extended inside the spindle and rotates in conjunction with the rotation of the spindle while reciprocating in the axial direction; and a collet that is coupled to the other side of the clamp bar so as to be coupled with the axial reciprocating movement of the clamp bar inside the spindle and clamps or unclamps the tool unit; and the spindle is axially extended inside the housing unit so that the tool unit is detachably coupled to the other side of the spindle to rotate the tool unit.

[0035] The friction stir welding machine tool according to the present invention supplies cooling fluid to the front end surface of the spindle where the spindle unit and the tool unit are connected, thereby efficiently blocking the heat generated in the tool unit from being transferred to the spindle unit and the bearing unit, thereby preventing thermal expansion of the spindle unit and the bearing unit, thereby preventing damage to the spindle unit and the bearing unit, thereby reducing the maintenance cost of the machine tool and improving the durability of the machine tool.

[0036] In addition, the friction stir welding machine tool according to the present invention can reduce the production cost of the machine tool by cooling the closest contact surface to the tool where heat is generated without the need to attach an expensive separate attachment, and has the effect of maximizing the productivity of the machine tool by cooling the heat transferred from the tool unit to the spindle unit and the tool unit without reducing the friction stir welding speed.

[0037] FIG. 1 is a perspective view showing a state in which a tool unit is removed from a spindle unit of a friction stir welding machine tool according to one embodiment of the present invention.

[0038] Figure 2 shows a perspective view of the tool unit attached to the spindle unit in Figure 1.

[0039] FIG. 3 shows a cross-sectional view of a spindle unit of a friction stir welding machine tool according to one embodiment of the present invention, with the tool unit removed.

[0040] Fig. 4 shows a cross-sectional view of the tool unit attached to the spindle unit in Fig. 3.

[0041] Figure 5 (a) shows a front view of the tool unit removed from the spindle unit, and (b) shows a front view of the tool unit attached and coupled to the spindle unit.

[0042] Fig. 6 is a perspective view showing a state in which a tool unit is removed from a spindle unit of a friction stir welding machine tool according to another embodiment of the present invention.

[0043] Figure 7 shows a perspective view of the tool unit attached and coupled to the spindle unit in Figure 6.

[0044] Fig. 8 shows a cross-sectional view of a spindle unit of a friction stir welding machine tool according to another embodiment of the present invention, with the tool unit removed.

[0045] Figure 9 shows a cross-sectional view of the tool unit attached to the spindle unit in Figure 8.

[0046] Fig. 10 shows a front view of the tool unit removed from the spindle unit to explain another embodiment of the arrangement relationship between the branch section and the discharge section in Fig. 5 (a).

[0047] Hereinafter, a friction stir welding machine tool according to an embodiment of the present invention will be described in detail with reference to drawings. The embodiments introduced below are provided as examples to ensure that the spirit of the present invention can be sufficiently conveyed to those skilled in the art. Therefore, the present invention is not limited to the embodiments described below and may be embodied in other forms. In addition, in the drawings, the size and thickness of the device may be exaggerated for convenience. Like reference numbers represent like elements throughout the specification.

[0048] The advantages and features of the present invention, and the methods for achieving them, will become clearer with reference to the embodiments described in detail below together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various different forms. These embodiments are provided only to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention, and the present invention is defined only by the scope of the claims. Like reference numerals designate like elements throughout the specification. The sizes and relative sizes of layers and regions in the drawings may be exaggerated for clarity of description.

[0049] The terminology used herein is for the purpose of describing embodiments and is therefore not intended to be limiting of the present invention. In this specification, the singular also includes the plural unless specifically stated otherwise. As used herein, the terms "comprise" and / or "comprising" do not exclude the presence or addition of one or more other components, steps, operations, and / or elements mentioned.

[0050] Fig. 1 is a perspective view of a friction stir welding machine tool according to one embodiment of the present invention, with the tool unit removed from the spindle unit. Fig. 2 is a perspective view of a tool unit attached and coupled to the spindle unit in Fig. 1.

[0051] Fig. 3 shows a cross-sectional view of a spindle unit of a friction stir welding machine tool according to one embodiment of the present invention, with the tool unit removed. Fig. 4 shows a cross-sectional view of a spindle unit of Fig. 3, with the tool unit attached and coupled to it.

[0052] Fig. 5 (a) shows a front view of a state in which a tool unit is removed from a spindle unit, and (b) shows a front view of a state in which a tool unit is attached and coupled to a spindle unit. Fig. 6 shows a perspective view of a state in which a tool unit is removed from a spindle unit of a friction stir welding machine tool according to another embodiment of the present invention.

[0053] Fig. 7 is a perspective view showing a state in which a tool unit is attached and coupled to a spindle unit in Fig. 6. Fig. 8 is a cross-sectional view showing a state in which a tool unit is removed from a spindle unit of a friction stir welding machine tool according to another embodiment of the present invention.

[0054] Fig. 9 shows a cross-sectional view of the tool unit attached and coupled to the spindle unit in Fig. 8. Fig. 10 shows a front view of the tool unit removed from the spindle unit to explain another embodiment of the arrangement relationship between the branch flow path and the discharge section in Fig. 5 (a).

[0055] A friction stir welding machine tool (1) according to the present invention will be described with reference to FIGS. 1 to 10.

[0056] As illustrated in FIGS. 1 to 10, a friction stir welding machine tool (1) may include a housing unit (100), a spindle unit (200), a bearing unit (300), and a tool unit (400).

[0057] The housing unit (100) of the friction stir welding machine tool (1) according to the present invention forms the exterior of the friction stir welding machine tool (1) and can protect the spindle unit (200), bearing unit (300), tool unit (400), etc., which are arranged inside.

[0058] The spindle unit (200) of the friction stir welding machine tool (1) according to the present invention can be rotatably arranged inside the housing unit (100).

[0059] The spindle unit (200) may be composed of a spindle (210), a clamp bar (220), and a collet (230).

[0060] The spindle (210) can be rotated by the rotational driving force of the motor (M).

[0061] And, the spindle (210) is extended in the axial direction (X) inside the housing unit (100).

[0062] In addition, the tool unit (400) is detachably connected to the other side of the spindle (210), so that the tool unit (400) can be rotated while attached to the spindle.

[0063] The spindle (210) may have a receiving portion (211) formed on a part of the inside of the other side.

[0064] A part of the tool holder (410) of the tool unit (400) is accommodated in the receiving portion (211), and a part of the accommodated tool holder (410) can be clamped by a collet (230) placed inside the spindle (210).

[0065] The other side means the right side in the axial direction (X), and specifically refers to the right side in FIGS. 3 to 4 and 8 to 9.

[0066] In addition, one side means the left side of the axial direction (X), and specifically refers to the left side in FIGS. 3 to 4 and 8 to 9.

[0067] The clamp bar (220) is extended in the axial direction (X) inside the spindle (210) and can reciprocate in the axial direction (X) while rotating in conjunction with the rotation of the spindle (210).

[0068] The collet (230) is coupled to the other side of the clamp bar (220) so as to be linked to the axial (X) reciprocating movement of the clamp bar (220) inside the spindle (210) to clamp or unclamp the tool unit (400).

[0069] That is, the collet (230) can clamp or unclamp the shank portion of the tool holder (410) of the tool unit (400).

[0070] The bearing unit (300) of the friction stir welding machine tool (1) according to the present invention can be placed between the housing unit (100) and the spindle unit (200) to support the rotation of the spindle unit (200).

[0071] Specifically, the bearing unit (300) can be placed between the rotating spindle (210) and the housing unit (100) to support the rotation of the spindle (210) and enable the spindle to rotate smoothly.

[0072] Although not necessarily limited thereto, the bearing unit (300) may have multiple bearings extended in the axial direction (X) between the spindle (210) and the housing unit (100) as shown in the drawing.

[0073] The tool unit (400) of the friction stir welding machine tool (1) according to the present invention can rotate in conjunction with the spindle unit (100) to perform friction stir welding on a material.

[0074] The tool unit (400) may be composed of a tool holder (410) and a tool (420).

[0075] A tool (420) can be mounted on the tool holder (410), and the spindle unit and the tool unit can be attached and connected as the tool holder (410) is partially inserted and connected to the receiving portion (211) of the spindle (210).

[0076] The present invention relates to a machine tool for performing friction stir welding (FSW). Friction stir welding (FSW) means that when a tool having a screw-shaped protrusion is inserted into a material to be joined while rotating at high speed, heat is generated by mutual friction between the tool and the material to be joined, the material on the tool's peripheral surface is softened by this frictional heat, and the materials on both sides of the joining surface are forcibly mixed by plastic flow of the material due to stirring of the tool, thereby welding the material to be joined.

[0077] Friction stir welding (FSW) with these characteristics can be performed only when the frictional heat between the tool and the material is maintained.

[0078] Therefore, unlike a general machine tool, if a channel for the cooling fluid to flow is formed directly at the center of the axis of the tool (420), the frictional heat for performing friction stir welding is cooled down, making it impossible to perform friction stir welding. Therefore, the friction stir welding machine tool (1) according to the present invention has a characteristic in that a channel for the flow of cooling fluid cannot be formed at the center of the tool (420).

[0079] Based on these characteristics, the process of cooling the friction stir welding machine tool (1) according to the present invention by a cooling fluid is described below.

[0080] The friction stir welding machine tool (1) according to the present invention can perform cooling by having the cooling fluid (F) introduced into one side of the spindle unit (200) flow to the other side of the spindle unit (200) and then discharged to the outside of the spindle unit (200).

[0081] That is, the cooling fluid (F) flows into the supply passage (510) arranged on one side of the spindle unit (200), flows through the core passage (520), space passage (530), branch passage (540), tool passage (550), and tip passage (560), and is finally discharged to the outside of the spindle unit (200) through the discharge passage (570).

[0082] As described above, the conventional friction stir welding machine tool (1) could not form a flow path for the flow of cooling fluid in the center of the tool (420), so the structure did not allow the cooling fluid to be discharged to the outside through the tool, and thus the flow of cooling fluid could not be utilized, and the friction stir welding speed was lowered to a level that was in equilibrium with natural cooling, or a roundabout method of using a separate, expensive, separate attachment head was chosen, resulting in a problem of reduced productivity or an increase in the production cost of the machine tool.

[0083] However, the friction stir welding machine tool (1) according to the present invention can solve the problem of the prior art by cooling the cooling fluid (F) introduced into one side of the spindle unit (200) by flowing in the axial direction and then flowing to the other side of the spindle unit (200) and then being discharged to the outside of the spindle unit (200).

[0084] Although not shown in the drawing, the supply path (510) is connected to a supply source that supplies cooling fluid and can receive cooling fluid.

[0085] The supply flow path (510) can be formed through the housing unit (100), and the other end is connected to the core flow path (520) to serve as a passage for the cooling fluid supplied from the supply source to flow into the core flow path (520).

[0086] The core euro portion (520) is formed to extend through a part of the spindle unit (200).

[0087] Specifically, the core flow path (520) can be formed to extend axially (X) through the clamp bar (220) to allow the cooling fluid (F) supplied from the supply flow path (510) to flow to the collet (230).

[0088] As the cooling fluid flows through the core euro section (520), the clamp bar (220) and the spindle (210) can be cooled.

[0089] The space section (530) can form a closed circulation space inside by the tool unit (400) and the spindle (210) to allow the cooling fluid transmitted through the core passage section (520) to flow to the branch passage section (540) while the tool unit (400) is coupled to the spindle (210).

[0090] That is, the space section (530) forms a closed circulation space inside the other side of the spindle by the tool unit (400) and the collet (230) so that the cooling fluid transmitted through the core passage section (520) flows while the tool unit (400) is coupled to the other side of the spindle (210).

[0091] Before the tool unit (400) is attached, a receiving portion (211) is formed on the other side of the spindle (210), and when the tool unit (400) is attached and combined to the receiving portion (211) of the spindle (210), a part of the tool unit (400) is clamped to a collet placed inside the spindle, thereby forming a space portion (530), which is a closed circulating space, inside the other side of the spindle by the tool unit (400) and the collet (230).

[0092] The cooling fluid flowing through the core euro (520) flows between the gaps of the collet and cools the collet (230).

[0093] The tool flow path (550) may be formed to extend inside the tool unit (400) so as to be in communication with at least one of the core flow path (520) or the space part (530).

[0094] The tool path (550) is formed in the tool holder (410) of the tool unit (400), and as described above, the tool path (550) is not formed in the tool (420) to maintain frictional heat for performing friction stir welding.

[0095] The tool flow path (550) is connected to at least one of the core flow path (520) and the space part (530) to cool the tool holder (410) through a cooling fluid, thereby preventing excessive heat generated from the tool (420) from being conducted.

[0096] The branch flow path (540) serves to flow the cooling fluid transmitted through the core flow path (520) to the front end surface (AA) of the spindle.

[0097] The branch flow path (540) can be formed through the other side of the spindle (210) so that the cooling fluid flowing into the space section (530) flows to the front end surface (AA) of the spindle.

[0098] The above branch flow path (540) can supply cooling fluid to the front end surface (AA) of the spindle where the spindle unit (200) and the tool unit (400) are coupled, thereby blocking heat generated in the tool unit (400) from being transferred to the spindle unit (200) and the bearing unit (300).

[0099] The branch section (540) may include a first branch section (541) and a second branch section (542).

[0100] Additionally, the branch section (540) can be formed on one or more spindles (210) according to the type of machine tool.

[0101] The first branch section (541) can be formed to penetrate the spindle (210) so that one end is connected to the space section (530) and the other end is adjacent to the bearing unit (300).

[0102] As described above, but not necessarily limited thereto, the bearing unit (300) is arranged between the housing unit (100) and the spindle unit (200) to support the rotation of the spindle unit (200), and as shown in the drawing, a plurality of bearings may be arranged to extend in the axial direction (X) between the spindle (210) and the housing unit (100).

[0103] In this case, when the bearing unit (300) is extended in the axial direction (X), the first branch flow path (541) can be formed to be inclined outward while facing the direction adjacent to the bearing unit (300), that is, one side of the axial direction.

[0104] The first branch section (541) can cool the bearing unit (300) and spindle (210) by flowing the cooling fluid flowing from the space section (530) to the bearing unit.

[0105] The second branch flow path (542) can be formed through the spindle (210) so that one end is connected to the first branch flow path (541) and the other end is connected to the tip flow path (560).

[0106] The second branch flow path (542) is connected to the other end of the first branch flow path (541), and is formed to extend toward the other axial side of the spindle (210) from the other end of the first branch flow path (541), so that, like the first branch flow path (541), the bearing unit (300) and the spindle (210) can be cooled.

[0107] The tip channel (560) can be formed by being inserted into the tip surface (AA) of the spindle in the axial direction (X) along the circumferential direction (L) based on the axis center (C) so that the cooling fluid flowing in through the branch channel (540) flows in the circumferential direction (L).

[0108] The tip channel (560) is a groove formed in a circular shape on the tip surface (AA) of the spindle, and a branch channel (540) is arranged on the bottom surface, so that the cooling fluid flowing in from the branch channel (540) flows in the circumferential direction along the tip channel (560).

[0109] In this way, the cooling fluid introduced from the branch flow path (540) flows in the circumferential direction along the tip flow path (560), thereby cooling the entire portion where the tool unit and the spindle unit are tightly coupled along the circumferential direction.

[0110] The discharge section (570) is formed to be spaced apart from the branch section (540) in the circumferential direction (L) along the tip section (560) and can discharge the cooling fluid flowing along the tip section (560) to the outside of the tip section.

[0111] Additionally, one or more discharge sections (570) may be formed to suit the type of machine tool.

[0112] The discharge section (570) is connected to the tip channel section (560). It has a predetermined width in the circumferential direction and a predetermined length in the outer radial direction, and is formed by being recessed in the axial direction to serve as a passage for discharging the cooling fluid flowing along the tip channel section (560) to the outside of the tip channel section.

[0113] Referring to Fig. 5(a), the branch flow path (540) and the discharge portion (570) may be arranged radially in multiple numbers so as to be spaced apart from each other at a predetermined angle along the circumferential direction (L) based on the axis center (C).

[0114] That is, the cooling fluid flowing in from each branch flow path (540) flows in the circumferential direction along the tip flow path (560) and is then discharged to the outside through the adjacent discharge part (570).

[0115] As described above, the cooling fluid flows through the multiple branch flow paths (540), so that the cooling fluid ultimately flows along the circumferential direction throughout the entire branch flow path (540).

[0116] Through this, the entire cross-section of the spindle can be cooled by the cooling fluid along the circumferential direction.

[0117] Referring to FIG. 10, the plurality of branch flow paths (540) and the plurality of discharge parts (570) may be arranged differently from FIG. 5.

[0118] That is, the above discharge unit (570) can be arranged in multiple pieces spaced apart at a predetermined angle along the circumferential direction (L) based on the axis center (C).

[0119] In addition, the branch flow path (540) may be arranged in two or more places so as to be spaced apart at a predetermined angle along the circumferential direction (L) with respect to the axis center (C) between the discharge parts (570) that are arranged adjacently along the circumferential direction (L) with respect to the axis center (C).

[0120] When arranged in this manner, the cooling rate can be further increased by increasing the flow rate of the cooling fluid through a number of branch flow paths (540).

[0121] The friction stir welding machine tool (1) according to the present invention can block heat generated in the tool unit (400) from being transferred to the spindle unit (200) and the bearing unit (300) by supplying cooling fluid to the front end surface (AA) of the spindle where the spindle unit (200) and the tool unit (400) are coupled.

[0122] As described above, the cooling fluid (F) flows into the supply passage (510) located on one side of the spindle unit (200), flows through the core passage (520), space passage (530), branch passage (540), tool passage (550), and tip passage (560), and is finally discharged to the outside of the spindle unit (200) through the discharge passage (570).

[0123] The cooling fluid flowing to the tool passage (550) through the core passage (520) and space passage (530) directly cools the tool holder (410) rather than the tool (420).

[0124] Additionally, the cooling fluid flowing through the core section (520) and space section (530) to the branch section (540) cools the spindle, collet, and bearing unit.

[0125] The cooling fluid introduced into the tip channel (560) through the branch channel (540) flows in the circumferential direction along the tip channel and is finally discharged to the outside of the spindle unit (200) through the discharge channel (570) to supply the cooling fluid to the tip end surface (AA) of the spindle where the spindle unit (200) and the tool unit (400) are connected, cool it, and then discharge it.

[0126] In this way, the friction stir welding machine tool (1) according to the present invention maintains the frictional heat generated between the tool and the material for performing friction stir welding, while blocking the heat generated from the tool from being transferred to the spindle unit and the bearing unit, thereby improving the friction stir welding quality while simultaneously increasing the durability of the machine tool and maximizing the processing speed and operating time of the machine tool, thereby maximizing productivity.

[0127] Although the detailed description of the present invention described above has been described with reference to preferred embodiments of the present invention, it will be understood by those skilled in the art or having ordinary knowledge in the art that various modifications and changes can be made to the present invention without departing from the spirit and technical scope of the present invention as set forth in the claims below. Accordingly, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification, but should be defined by the claims.

[0128] <Explanation of symbols>

[0129] 1: Machine tools for friction stir welding

[0130] 100: Housing Unit

[0131] 200: Spindle unit

[0132] 300: Bearing unit

[0133] 400: Tool Unit

Claims

1. Housing unit; A spindle unit having a spindle and rotatably positioned inside the housing unit; A bearing unit disposed between the housing unit and the spindle unit to support rotation of the spindle unit; A tool unit that rotates in conjunction with the spindle unit to perform friction stir welding on a material; A core portion formed by extending through a portion of the spindle unit; and A friction stir welding machine tool characterized by including a branch flow path for flowing the cooling fluid transmitted through the core flow path to the front end surface of the spindle.

2. In paragraph 1, A friction stir welding machine tool further comprising a space section forming a closed circulation space inside by the tool unit and the spindle to allow the cooling fluid transmitted through the core passage section to flow to the branch passage section while the tool unit is coupled to the spindle.

3. In paragraph 1, A friction stir welding machine tool, characterized in that the branch section supplies cooling fluid to the front end surface of the spindle where the spindle unit and the tool unit are coupled, thereby blocking heat generated in the tool unit from being transferred to the spindle unit and the bearing unit.

4. In paragraph 2, A friction stir welding machine tool, characterized in that it further includes a tool channel portion formed extending inside the tool unit so as to be in communication with at least one of the core channel portion and the space portion.

5. In paragraph 1, A friction stir welding machine tool, characterized in that it further includes a tip channel section formed axially along the circumferential direction based on the axis center on the tip surface of the spindle so that the cooling fluid transmitted through the branch channel section flows in the circumferential direction.

6. In paragraph 5, A friction stir welding machine tool, characterized in that it further includes a discharge section formed in a circumferential direction along the tip passage section and spaced apart from the branch passage section, and discharging the cooling fluid flowing along the tip passage section to the outside of the tip passage section.

7. In paragraph 2, The above quarterly euro area is, A first branch section formed through the spindle so that one end is connected to the space section and the other end is adjacent to the bearing unit; and A friction stir welding machine tool characterized by including a second branch passage formed through the spindle so that one end is connected to the first branch passage and the other end is connected to the tip passage.

8. In paragraph 6, A friction stir welding machine tool, characterized in that the branch section and the discharge section are arranged radially in multiple numbers so as to be spaced apart from each other at a predetermined angle along the circumferential direction based on the axis center.

9. In paragraph 6, A friction stir welding machine tool characterized in that the above discharge portions are arranged in multiple units spaced apart at a predetermined angle along the circumferential direction based on the axis center.

10. In accordance with paragraph 9, A friction stir welding machine tool, characterized in that two or more of the above branching sections are arranged so as to be spaced apart at a predetermined angle in the circumferential direction based on the axis center between the discharge sections arranged adjacently in the circumferential direction based on the axis center.

11. In paragraph 1, The above spindle unit, A clamp bar that extends axially inside the spindle and rotates in conjunction with the rotation of the spindle while reciprocating in the axial direction; and A collet is coupled to the other side of the clamp bar to clamp or unclamp the tool unit so as to link with the axial reciprocating movement of the clamp bar inside the spindle; A friction stir welding machine tool, characterized in that the spindle is axially extended inside the housing unit, and the tool unit is detachably coupled to the other side of the spindle to rotate the tool unit.

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