BACKGROUND OF THE INVENTION
[0001] The present invention relates to a yarn threading robot configured to perform yarn
               threading onto a spun yarn take-up apparatus.
 
            [0002] Patent Literature 1 (Japanese Unexamined Patent Publication No.
 S53-106815), for example, discloses an automatic yarn threading device configured to perform
               yarn threading onto a spun yarn take-up apparatus configured to wind spun yarns to
               form packages. The automatic yarn threading device is configured to operate while
               sucking and retaining the yarns by a suction gun, to enable yarn threading onto elements
               structuring the spun yarn take-up apparatus.
 
            SUMMARY OF THE INVENTION
[0003] Now, consideration is given to the case in which yarn threading is performed while
               yarns are sucked and retained by a suction gun. In this case, if the suction force
               of the suction gun is too small, yarn swaying or the like may occur, causing a possibility
               that yarn threading onto each element cannot be properly performed. Meanwhile, if
               the suction force of the suction gun is too large, the tension of the yarns may become
               too high, with the result that yarn breakage may be caused, and/or vibration of the
               yarns caused by the suction may be propagated excessively. That is, if the suction
               force of the suction gun is not properly controlled, there is a high possibility that
               yarn threading is failed. However, in Patent Literature 1, no mention is made of the
               control of the suction force of the suction gun to stably perform yarn threading.
 
            [0004] The present invention has been made in view of the above problem. An object of the
               present invention is to provide a yarn threading robot capable of stably performing
               yarn threading.
 
            [0005] According to an aspect of the present invention, a yarn threading robot configured
               to perform yarn threading onto a spun yarn take-up apparatus while sucking and retaining
               a yarn by a sucking retaining unit is provided, the spun yarn take-up apparatus being
               configured to wind the spun-out yarn onto a bobbin while traversing the yarn to form
               a package. The yarn threading robot includes a controller configured to control a
               suction force of the sucking retaining unit.
 
            [0006] The yarn threading robot of the above aspect of the present invention includes the
               controller configured to control the suction force of the sucking retaining unit.
               Due to this, it is possible to stably perform yarn threading by increasing or decreasing
               the suction force as needed.
 
            [0007] Furthermore, in the above aspect of the present invention, it is preferable that:
               the sucking retaining unit is configured so that compressed fluid is supplied to the
               sucking retaining unit and thereby a suction force corresponding to a pressure of
               the compressed fluid is generated; and the controller is configured to control the
               suction force of the sucking retaining unit by controlling the pressure of the compressed
               fluid supplied to the sucking retaining unit.
 
            [0008]  In the above arrangement, the suction force of the sucking retaining unit can be
               easily increased or decreased merely by adjusting the pressure of the compressed fluid.
 
            [0009] Furthermore, in the above aspect of the present invention, it is preferable that:
               the yarn threading robot further includes a pressure adjuster configured to adjust
               the pressure of the compressed fluid, the pressure adjuster provided to a path through
               which the compressed fluid is supplied to the sucking retaining unit; and the controller
               is configured to control the suction force of the sucking retaining unit by controlling
               operation of the pressure adjuster.
 
            [0010] Because the pressure adjuster configured to adjust the pressure of the compressed
               fluid is provided to the yarn threading robot, the distance between the pressure adjuster
               and the sucking retaining unit is short, which provides quick responsivity in the
               control of the suction force.
 
            [0011] In the above aspect of the present invention, it is preferable that the pressure
               adjuster is an electro-pneumatic regulator.
 
            [0012] The use of the electro-pneumatic regulator as the pressure adjuster allows the pressure
               of the compressed fluid to be adjusted in a substantially non-step manner, which allows
               minute control of the suction force of the sucking retaining unit.
 
            [0013] In the above aspect of the present invention, it is preferable that the controller
               is configured to change the suction force of the sucking retaining unit in a single
               set of processes of yarn threading.
 
            [0014] Even in a single set of processes of yarn threading, proper suction force can change
               depending on which of the processes is performed. In the above-mentioned arrangement,
               it is possible to deal with the case where the proper suction force changes within
               the single set of processes of yarn threading, thereby to enable more stable yarn
               threading.
 
            [0015] Furthermore, in the above aspect of the present invention, it is preferable that
               the controller controls the suction force of the sucking retaining unit so that the
               suction force in a process of yarn threading onto the bobbin is the largest in the
               single set of processes of yarn threading.
 
            [0016] Generally, in the process of yarn threading onto a bobbin, it is necessary to thread
               a yarn into a slit of the bobbin. Due to this, if the suction force is insufficient
               in the process of yarn threading onto the bobbin, the tension of the yarn may be too
               low, resulting in unsuccessful yarn threading into the slit. In the above-mentioned
               arrangement, the suction force is adjusted so that the suction force in the process
               of yarn threading onto the bobbin is the largest in the single set of processes of
               yarn threading. This makes it easier to thread the yarn into the slit, and enables
               reliable yarn threading onto the bobbin.
 
            [0017] In the above aspect of the present invention, it is preferable that the controller
               changes the suction force of the sucking retaining unit based on a type of yarn wound
               by the spun yarn take-up apparatus and/or based on a production condition.
 
            [0018] Proper tensions in the processes of yarn threading may differ depending on the type
               of yarn and/or production conditions. Even in such a case, each process of yarn threading
               is performed with a tension suitable for a subject yarn by changing the suction force
               depending on the type of yarn and/or production conditions, as described above.
 
            BRIEF DESCRIPTION OF THE DRAWINGS
[0019] 
               
               FIG. 1 is a schematic diagram of a spun yarn take-up system of an embodiment of the
                  present invention.
               FIG. 2 is a front view illustrating a spun yarn take-up apparatus and a yarn threading
                  robot.
               FIG. 3 is a side view illustrating the spun yarn take-up apparatus and the yarn threading
                  robot.
               FIG. 4 is a block diagram illustrating an electric structure of the spun yarn take-up
                  system.
               FIG. 5(a) and FIG. 5(b) are top views of fulcrum guides.
               FIG. 6 is a perspective view illustrating a yarn threading unit of the yarn threading
                  robot.
               FIG. 7 is a cross-section of a suction.
               FIG. 8(a) to FIG. 8(e) are side views showing the operation of the yarn threading
                  robot at the time of yarn threading.
               FIG. 9(a) to FIG. 9(c) are top views showing the operation of the yarn threading robot
                  at the time of yarn threading.
               FIG. 10 is a top view showing the operation of the yarn threading robot at the time
                  of yarn threading.
               FIG. 11 is a top view showing the operation of yarn threading from a yarn separation
                  guide to the fulcrum guides.
               FIG. 12 is a graph showing an example of control of the suction force of the suction.
 
            DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0020] The following will describe a preferred embodiment of the present invention.
 
            (Overall Structure of Spun Yarn Take-Up System)
[0021] FIG. 1 is a schematic diagram of a spun yarn take-up system of the present embodiment.
               The spun yarn take-up system 1 of the present embodiment includes: a plurality of
               spun yarn take-up apparatuses 2 lined up in one horizontal direction; yarn threading
               robots 3 configured to perform yarn threading onto the spun yarn take-up apparatuses
               2; a centralized controller 4 configured to control the operation of each spun yarn
               take-up apparatus 2 and the operation of each yarn threading robot 3; compressed air
               suppliers 5 configured to supply compressed air (an example of compressed fluid) to
               the yarn threading robots 3; and waste yarn boxes 6 configured to receive waste yarns
               from the yarn threading robots 3. In the present embodiment, one yarn threading robot
               3, one compressed air supplier 5, and one waste yarn box 6 are provided for each of
               the spun yarn take-up apparatuses 2 included in the spun yarn take-up system 1. In
               FIG. 1, yarns are not illustrated to avoid complexity in the figure. Hereinafter,
               the direction in which the spun yarn take-up apparatuses 2 are lined up is referred
               to as a left-right direction, and the direction which is horizontal and orthogonal
               to the left-right direction is referred to as a front-back direction.
 
            (Spun Yarn Take-Up Apparatus)
[0022] Now, the details of each spun yarn take-up apparatus 2 will be described. FIG. 2
               is a front view showing the spun yarn take-up apparatus 2 and the yarn threading robot
               3. FIG. 3 is a side view showing the spun yarn take-up apparatus 2 and the yarn threading
               robot 3. FIG. 4 is a block diagram showing the electric structure of the spun yarn
               take-up system 1.
 
            [0023] The spun yarn take-up apparatus 2 is configured to take up yarns Y spun out from
               an unillustrated spinning apparatus, to wind the yarns onto bobbins B, and to form
               packages P. More specifically, the spun yarn take-up apparatus 2 is configured to
               feed the yarns Y spun out from the unillustrated spinning apparatus to a winding unit
               13 by a first godet roller 11 and a second godet roller 12, and to wind the yarns
               Y onto the bobbins B in the winding unit 13, thereby to form packages P.
 
            [0024] The first godet roller 11 is a roller having an axis substantially in parallel to
               the left-right direction and is provided above a front end portion of the winding
               unit 13. The first godet roller 11 is rotationally driven by a first godet motor 111
               (see FIG. 4).
 
            [0025] The second godet roller 12 is a roller having an axis substantially in parallel to
               the left-right direction and is provided above and backward of the first godet roller
               11. The second godet roller 12 is rotationally driven by a second godet motor 112
               (see FIG. 4). The second godet roller 12 is movably supported by a guide rail 14.
               The guide rail 14 extends obliquely with respect to an up-down direction with a positive
               slope in the backward direction. The second godet roller 12 is configured to be movable
               along the guide rail 14 by a cylinder 113 (see FIG. 4). Due to this, the second godet
               roller 12 is movable between a winding position (indicated by solid lines in FIG.
               3) in which winding of the yarns Y is performed and a yarn threading position (indicated
               by dashed lines in FIG. 3) in which yarn threading is performed. The yarn threading
               position is closer to the first godet roller 11 than the winding position.
 
            [0026] The spun yarn take-up apparatus 2 further includes an aspirator 15 and a yarn regulating
               guide 16. The aspirator 15 is configured to suck and retain the yarns Y spun out from
               the spinning apparatus before yarn threading is performed by the yarn threading robot
               3. The aspirator 15 extends along the left-right direction. The aspirator 15 has,
               at its right end portion, a suction port 15a for sucking the yarns Y. The aspirator
               15 is provided somewhat above the first godet roller 11 so that the suction port 15a
               is positioned near the yarns Y.
 
            [0027] The yarn regulating guide 16 is provided between the first godet roller 11 and the
               aspirator 15 with respect to the up-down direction. The yarn regulating guide 16 is,
               for example, a known yarn guide with a comb teeth shape including guide grooves. The
               yarn regulating guide 16 functions to regulate the intervals between neighboring yarns
               Y threaded thereon. The yarn regulating guide 16 is arranged to be movable in the
               left-right direction (the axial direction of the first godet roller 11) by a cylinder
               114 (see FIG. 4). Due to this arrangement, in the left-right direction, the yarn regulating
               guide 16 is movable between: a retracted position (indicated by solid lines in FIG.
               2) where the guide 16 falls within the range of the first godet roller 11; and a protruding
               position (indicated by dashed lines in FIG. 2) where the guide 16 is to the right
               of a leading end portion of the first godet roller 11.
 
            [0028] The winding unit 13 includes: fulcrum guides 21; traverse guides 22; a turret 23;
               two bobbin holders 24; and a contact roller 25.
 
            [0029] FIG. 5(a) and FIG. 5(b) are top views of the fulcrum guides 21. The fulcrum guides
               21 are provided for the yarns Y, respectively, and are lined up in the front-back
               direction. Each fulcrum guide 21 has a groove 21a which is open to the back side.
               Yarn threading onto the fulcrum guide 21 is performed by inserting the yarn Y into
               the groove 21a from the back side. The fulcrum guides 21 are attached to sliders 27,
               respectively. The sliders 27 are supported to be movable in the front-back direction
               along a guide rail 28. The sliders 27 are connected to a cylinder 115 (see FIG. 4).
               As the cylinder 115 is driven, the sliders 27 move in the front-back direction along
               the guide rail 28. Due to this, the fulcrum guides 21 are movable between: winding
               positions (positions shown in FIG. 5(a)) where the fulcrum guides 21 are separated
               from one another in the front-back direction and winding of the yarns Y is performed;
               and yarn threading positions (positions shown in FIG. 5(b)) where the fulcrum guides
               21 are close to one another at a front end portion of the guide rail 28 and yarn threading
               is performed. The fulcrum guides 21 in their yarn threading positions are approximately
               straight below the first godet roller 11 and the second godet roller 12 in the yarn
               threading position.
 
            [0030] The traverse guides 22 are respectively provided for the yarns Y, and are lined up
               in the front-back direction. The traverse guides 22 are driven by a common traverse
               motor 116 (see FIG. 4) and reciprocate in the front-back direction. With this, the
               yarns Y threaded onto the traverse guides 22 are traversed about the fulcrum guides
               21.
 
            [0031] The turret 23 is a disc-shaped member having an axis which is substantially in parallel
               to the front-back direction. The turret 23 is rotationally driven by a turret motor
               117 (see FIG. 4). The two bobbin holders 24 have axes which are substantially in parallel
               to the front-back direction. The bobbin holders 24 are rotatably supported at an upper
               end portion and a lower end portion of the turret 23. Bobbins B are attached to each
               bobbin holder 24. The bobbins B are respectively provided for the yarns Y and lined
               up in the front-back direction. The two bobbin holders 24 are rotationally driven
               by their respective winding motors 118 (see FIG. 4).
 
            [0032] When the upper bobbin holder 24 is rotationally driven, the yarns Y traversed by
               the traverse guides 22 are wound onto the bobbins B, with the result that packages
               P are formed. After the completion of the formation of the packages P, the turret
               23 is rotated, to switch the positions of the two bobbin holders 24 with each other.
               As a result, the bobbin holder 24 having been at the lower position is moved to the
               upper position, which allows the yarns Y to be wound onto the bobbins B attached to
               the bobbin holder 24 having been moved to the upper position, to form packages P.
               Meanwhile, the bobbin holder 24 having been at the upper position is moved to the
               lower position, and the packages P are collected by a package collector which is not
               illustrated.
 
            [0033] The contact roller 25 is a roller having an axis substantially in parallel to the
               front-back direction and is provided immediately above the upper bobbin holder 24.
               The contact roller 25 is configured to contact the surfaces of the packages P supported
               by the upper bobbin holder 24. With this, the contact roller 25 applies a contact
               pressure to the surfaces of the unfinished packages P, to adjust the shape of the
               packages P.
 
            (Yarn Threading Robot)
[0034] Now, the yarn threading robot 3 will be described. The yarn threading robot 3 includes
               a main body 31, a robotic arm 32, and a yarn threading unit 33.
 
            [0035] The main body 31 is rectangular parallelepiped in shape, and has a robot controller
               102 (see FIG. 4) and the like mounted inside thereof. The robot controller 102 is
               configured to control operations of the robotic arm 32, the yarn threading unit 33,
               an electro-pneumatic regulator 37, and the like. The main body 31 hangs down from
               two guide rails 35 and is movable in the left-right direction along the two guide
               rails 35. The two guide rails 35 are provided in front of the spun yarn take-up apparatuses
               2 so as to be separate from each other in the front-back direction. Each guide rail
               35 extends in the left-right direction so as to cover the plurality of spun yarn take-up
               apparatuses 2. That is, the yarn threading robot 3 is configured to be movable in
               the left-right direction in front of the spun yarn take-up apparatuses 2.
 
            [0036] Four wheels 36 are provided at an upper end portion of the main body 31. Two of the
               four wheels 36 are on the upper surface of one of the guide rails 35, and the remaining
               two wheels 36 are on the upper surface of the other one of the guide rails 35. The
               four wheels 36 are rotationally driven by a movement motor 121 (see FIG. 4). As the
               four wheels 36 are rotationally driven, the main body 31 moves in the left-right direction
               along the two guide rails 35.
 
            [0037] The robotic arm 32 is attached to a lower surface of the main body 31. The robotic
               arm 32 includes arms 32a and joints 32b connecting the arms 32a with one another.
               Each joint 32b incorporates therein an arm motor 122 (see FIG. 4). As the arm motor
               122 is driven, the arm 32a is swung about the joint 32b. This arrangement allows the
               robotic arm 32 to move three-dimensionally.
 
            [0038]  FIG. 6 is a perspective view showing the yarn threading unit 33 of the yarn threading
               robot 3. The yarn threading unit 33 is attached to a distal end portion of the robotic
               arm 32. The yarn threading unit 33 is long in one direction. Hereinafter, this direction
               is referred to as a first direction. An end portion of the yarn threading unit 33,
               which is on one side in the first direction, is connected to the arm 32a. Hereinafter,
               the one side in the first direction is referred to as a base end side in the first
               direction. In addition to the above, hereinafter, the side opposite to the base end
               side in the first direction is referred to as a leading end side.
 
            [0039] In the present embodiment, as the robotic arm 32 is driven, the yarn threading unit
               33 attached to the distal end portion of the robotic arm 32 moves three-dimensionally.
               In so doing, the orientation of the yarn threading unit 33 is changeable. As described
               later, at the time of yarn threading, the yarn threading unit 33 is mainly used in
               an orientation such that the up-down direction in FIG. 6 is in parallel to the vertical
               direction, the upper side in FIG. 6 is the upper side in the vertical direction, and
               the lower side in FIG. 6 is the lower side in the vertical direction. In view of the
               above, hereinafter, directions relative to the yarn threading unit 33 are defined
               as follows: the up-down direction in FIG. 6 is referred to as a second direction;
               the upper side in FIG. 6 is referred to as the upper side in the second direction;
               and the lower side in FIG. 6 is referred to as the lower side in the second direction.
               Furthermore, hereinafter, a direction orthogonal to both the first direction and the
               second direction is defined as a third direction, and one side and the other side
               in the third direction are defined as shown in FIG. 6.
 
            [0040] The yarn threading unit 33 includes a frame 41, a suction 42, a yarn convergence
               guide 43, a cutter 44, a slidable component 45, a pressing roller 46, a yarn separation
               guide 47, and the like. The frame 41 is connected with the arm 32a at the base end
               portion in the first direction. The suction 42 is attached to a part of the frame
               41, which is on the one side in the third direction. The suction 42 extends in the
               first direction and is able to suck and retain the yarns Y at its leading end portion.
               The yarn convergence guide 43 is attached to the frame 41 and is below the leading
               end portion of the suction 42 in the second direction. Onto the yarn convergence guide
               43, the yarns Y are threaded in a converged state at the time of yarn threading. The
               cutter 44 is attached to the frame 41 and is below the yarn convergence guide 43 in
               the second direction. As described later, the cutter 44 is provided to cut the yarns
               Y when the yarns Y are passed from the aspirator 15 to the suction 42.
 
            [0041] The slidable component 45 is provided on the other side in the third direction of
               the suction 42, the yarn convergence guide 43, and the cutter 44. The slidable component
               45 is attached to the frame 41 via a cylinder 48. As the cylinder 48 is driven, the
               slidable component 45 moves in the first direction relative to the frame 41.
 
            [0042] The pressing roller 46 is a free roller rotatably supported by a shaft 46a which
               is orthogonal to the second direction. The pressing roller 46 is provided above the
               slidable component 45 in the second direction so as to be movable together with the
               slidable component 45 in the first direction. An end portion of the shaft 46a is attached
               to a hollow cylindrical shaft 49. The shaft 49 extends in the second direction to
               penetrate the slidable component 45. A roller swinging device 50 is connected to an
               end portion of the shaft 49, which is on the lower side in the second direction. The
               pressing roller 46 is configured to swingable about the axis of the shaft 49 by the
               roller swinging device 50 within a plane including the first direction and the third
               direction. The pressing roller 46 is swingable about the axis of the shaft 49, and
               this allows the pressing roller 46 to selectively take one of the following postures:
               a retreat posture (posture shown in FIG. 6) in which the axial direction of the pressing
               roller 46 is substantially in parallel to the first direction, and the entirety of
               the pressing roller 46 is on the other side in the third direction relative to a range
               in which the suction 42, the yarn convergence guide 43, and the cutter 44 are provided;
               and a pressing posture (posture shown in FIG. 9(a)) in which the axial direction of
               the pressing roller 46 is substantially in parallel to the third direction, and the
               pressing roller 46 partially overlaps, with respect to the third direction, the range
               in which the suction 42, the yarn convergence guide 43, and the cutter 44 are provided.
 
            [0043] The yarn separation guide 47 is provided above the pressing roller 46 in the second
               direction so as to be movable together with the slidable component 45 in the first
               direction. The yarn separation guide 47 has grooves 47a lined up along the length
               of the guide 47. Each of the grooves 47a is open at one end. The intervals between
               the grooves 47a increase in the direction away from the open ends. In this regard,
               the intervals between the grooves 47a may be constant regardless of the distance from
               the open ends. The yarn separation guide 47 is, at an end portion in its longitudinal
               direction, attached to an unillustrated shaft which extends to be in parallel to the
               second direction. The shaft is inserted through the hollow cylindrical shaft 49. A
               guide swinging device 51 is connected to a lower end portion of the shaft, which is
               on the lower side in the second direction. The yarn separation guide 47 is configured
               to be swung about the axis of the unillustrated shaft by the guide swinging device
               51. This allows the yarn separation guide 47 to selectively take one of the following
               postures: a retreat posture (posture shown in FIG. 6) in which the longitudinal direction
               of the yarn separation guide 47 is substantially in parallel to the first direction,
               and the entirety of the yarn separation guide 47 is on the other side in the third
               direction relative to the range in which the suction 42, the yarn convergence guide
               43, and the cutter 44 are provided; and a yarn threading posture (posture shown in
               FIG. 9(c)) in which the longitudinal direction of the yarn separation guide 47 is
               substantially parallel to the third direction, and the yarn separation guide 47 partially
               overlaps, with respect to the third direction, the range in which the suction 42,
               the yarn convergence guide 43, and the cutter 44 are provided.
 
            [0044] FIG. 7 is a cross-section of the suction 42. The suction 42 includes a suction pipe
               42a extending in the first direction, and a compressed air pipe 42b unitarily connected
               to an intermediate portion of the suction pipe 42a. A leading end portion of the suction
               pipe 42a functions as a suction port 42c through which the yarns Y are sucked. A base
               end portion of the suction pipe 42a is connected to a waste yarn hose 8 (see FIG.
               1), which is connected to the waste yarn box 6. A leading end portion of the compressed
               air pipe 42b communicates with the suction pipe 42a via a communication hole 42d.
               A base end portion of the compressed air pipe 42b is connected to a compressed air
               hose 7 (see FIG. 1), which is connected to the compressed air supplier 5. The communication
               hole 42d is inclined with respect to the suction pipe 42a so that an end of the communication
               hole 42d which is close to the suction pipe 42a is on the base end side relative to
               its opposite end. A part of the compressed air hose 7 and a part of the waste yarn
               hose 8 are attached to the main body 31 or the robotic arm 32 so as not to interfere
               with the operation of the robotic arm 32.
 
            [0045] In the suction 42 configured as above, compressed air having flowed from the compressed
               air pipe 42b into the suction pipe 42a flows from the leading end side to the base
               end side of the suction pipe 42a, as indicated by an arrow in FIG. 7. This airflow
               creates a vacuum or a negative pressure at the suction port 42c, which makes it possible
               to suck the yarns Y from the suction port 42c. The yarns Y sucked from the suction
               port 42c are discharged to the waste yarn hose 8 along with the airflow in the suction
               pipe 42a. The yarn threading robot 3 performs yarn threading while sucking and retaining
               the yarns Y using the suction 42.
 
            [0046] As described above, the suction 42 of the present embodiment is configured so that
               suction force (vacuum) is created at the suction port 42c by compressed air supplied
               from the compressed air supplier 5. The suction force of the suction 42 is changeable
               by changing the pressure of compressed air supplied to the suction 42. In the present
               embodiment, as shown in FIG. 1, the electro-pneumatic regulator 37 is provided to
               a part of the compressed air hose 7, the part being provided to the yarn threading
               robot 3. The electro-pneumatic regulator 37 is able to adjust the pressure of compressed
               air in a substantially non-step manner, i.e., substantially continuously. This arrangement
               makes it possible to adjust the pressure of the compressed air supplied to the suction
               42, and thus it is possible to adjust the suction force of the suction 42.
 
            (Electric Structure of Spun Yarn Take-Up System)
[0047] Now, the electric structure of the spun yarn take-up system 1 will be described.
               As shown in FIG. 1, the spun yarn take-up system 1 includes the centralized controller
               4 which serves to control the entire system. The centralized controller 4 includes
               an operation unit 4a which allows an operator to make various settings, and a display
               unit 4b configured to display thereon a screen for assisting the settings and/or a
               screen showing the state of each component. As shown in FIG. 4, each spun yarn take-up
               apparatus 2 is provided with a winding controller 101. The winding controller 101
               is configured to control the operation of each driving unit of the spun yarn take-up
               apparatus 2. In the yarn threading robot 3, a robot controller 102 is provided. The
               robot controller 102 is configured to control the operation of each driving unit of
               the yarn threading robot 3. The centralized controller 4 is communicably connected,
               wirelessly or by cable, with each winding controller 101 and each robot controller
               102.
 
            (Flow of processes of yarn threading)
[0048] The following describes processes of yarn threading performed by the yarn threading
               robot 3. FIG. 8(a) to FIG. 8(e) are side views showing the operation of the yarn threading
               robot 3 at the time of yarn threading. FIG. 9(a) to FIG. 9(c) and FIG. 10 are top
               views showing the operation of the yarn threading robot 3 at the time of yarn threading.
               FIG. 11 is a top view showing the operation in which the yarns Y are threaded from
               the yarn separation guide 47 to the fulcrum guides 21. To be more specific, FIG. 8(a)
               to FIG. 8(e) show the process of receiving the yarns Y spun out from the spinning
               apparatus and winding the yarns Y onto the first godet roller 11 and the second godet
               roller 12. This process is one of the processes of yarn threading. FIG. 9(a) to FIG.
               9(c) and FIG. 10 show the process of threading the yarns Y onto the yarn separation
               guide 47 of the yarn threading robot 3. In FIG. 8(a) to FIG. 8(e), the yarn threading
               unit 33 is oriented such that the first direction of the yarn threading unit 33 is
               substantially in parallel to the front-back direction, for the sake of convenience.
               In practice, however, yarn threading is performed while the posture of the yarn threading
               unit 33 is changed.
 
            [0049] As shown in FIG. 8(a), before yarn threading is performed by the yarn threading robot
               3, the yarns Y spun out from the spinning apparatus are sucked and retained by the
               aspirator 15 in advance. In addition, the second godet roller 12 of the spun yarn
               take-up apparatus 2 subjected to yarn threading is positioned at the yarn threading
               position, in advance. Furthermore, the fulcrum guides 21 are positioned at their yarn
               threading positions (positions shown in FIG. 5(b)), in advance. Furthermore, the pressing
               roller 46 and the yarn separation guide 47 of the yarn threading unit 33 are arranged
               to be in their respective retreat postures (postures shown in FIG. 6), in advance.
 
            [0050] Thereafter, the yarn threading robot 3 is moved to a position in which the robot
               3 overlaps the spun yarn take-up apparatus 2 subjected to yarn threading with respect
               to the front-back direction. Subsequently, the yarn threading robot 3 actuates the
               robotic arm 32, thereby to move the yarn threading unit 33 to a position somewhat
               above the aspirator 15, as shown in FIG. 8(b). At this time, the yarn threading unit
               33 is moved so that: the leading end portion of the suction 42 is pressed onto the
               yarns Y sucked and retained by the aspirator 15; and the cutter 44 is at a position
               which enables the cutter 44 to cut the yarns Y. Subsequently, the yarns Y are cut
               by the cutter 44. Then, as shown in FIG. 8(c), the yarns Y are sucked and retained
               by the suction 42, and thus handing over of the yarns Y from the aspirator 15 to the
               suction 42 is completed.
 
            [0051] After the completion of handing over of the yarns Y from the aspirator 15 to the
               suction 42, the yarns Y are threaded onto the yarn regulating guide 16 while the yarn
               threading unit 33 is moved to a position below the first godet roller 11, as shown
               in FIG. 8(d). To thread the yarns Y onto the yarn regulating guide 16, the yarn regulating
               guide 16 is moved to the protruding position (position indicated by the dashed line
               in FIG. 2) for a while, to avoid interference by the godet rollers 11 and 12 with
               the yarn threading unit 33. Then, the yarns Y are threaded onto the yarn regulating
               guide 16 in the protruding position. After yarn threading onto the yarn regulating
               guide 16, the yarn regulating guide 16 is returned to the retracted position (position
               indicated by the solid line in FIG. 2). Subsequently, the yarn threading unit 33 is
               moved appropriately to wind the yarns Y retained by the suction 42 onto the first
               godet roller 11 from below, and then to wind the yarns Y onto the second godet roller
               12 from above, as shown in FIG. 8(e).
 
            [0052] Now, yarn threading onto the fulcrum guides 21 will be described with reference to
               FIG. 9(a) to FIG. 9(c) and FIG. 10. After yarn threading onto the godet rollers 11
               and 12, the yarn threading robot 3 swings the pressing roller 46, to change its posture
               from the retreat posture to the pressing posture, as shown in FIG. 9(a). As a result,
               the pressing roller 46 is pressed onto the yarns Y and rotates due to the friction
               force with the yarns Y This widens the intervals of the yarns Y at the parts onto
               which the pressing roller 46 is pressed.
 
            [0053] Subsequently, as shown in FIG. 9(b), the slidable component 45 is slid toward the
               leading end side in the first direction. As a result, the pressing roller 46 pressed
               onto the yarns Y slides toward the leading end side in the first direction together
               with the slidable component 45, so as to move away from the suction 42. With this,
               as compared to the state shown in FIG. 9(a), the tilting angles of the yarns Y running
               from the pressing roller 46 to the suction 42 decrease. The tilting angles of the
               yarns Y are the angles of the yarns Y inclined with respect to the first direction
               when viewed in the second direction. In this regard, if the above tilting angles of
               the yarns Y are large, variations tend to be caused in the position where the yarns
               Y leave the pressing roller 46 toward the suction 42, and this may disadvantageously
               cause yarn swaying. To minimize yarn swaying, in the present embodiment, the tilting
               angles of the yarns Y are decreased by moving the pressing roller 46 away from the
               suction 42, as described above. As a result, the intervals between the yarns Y become
               substantially identical with the intervals between the openings of the grooves 47a
               of the yarn separation guide 47, which are substantially equal to the intervals between
               the guide grooves of the yarn regulating guide 16.
 
            [0054] Subsequently, as shown in FIG. 9(c), the yarn separation guide 47 is swung to change
               its posture from the retreat posture to the yarn threading posture. As a result, the
               grooves 47a of the yarn separation guide 47 are respectively opposed to the yarns
               Y onto which the pressing roller 46 is pressed. Subsequently, as shown in FIG. 10,
               the pressing roller 46 is swung to change its posture from the pressing posture to
               the retreat posture. As a consequence, the pressing roller 46 moves away from the
               yarns Y, and the yarns Y are inserted into the respective grooves 47a. In this connection,
               because the intervals between the grooves 47a increase in the direction away from
               the openings of the grooves 47a, the intervals between the yarns Y inserted into the
               grooves 47a further increase. Further, at this time, the yarn threading unit 33 is
               positioned so that linear lines each connecting one of the grooves 47a of the yarn
               separation guide 47 with the opening at the leading end of the groove 21a of the corresponding
               fulcrum guide 21 are in parallel to one another, as shown in FIG. 11.
 
            [0055] The yarn separation guide 47 in the above state is moved as shown in FIG. 11. As
               a result, the yarns Y inserted into the grooves 47a are respectively threaded onto
               the respective fulcrum guides 21. After the completion of yarn threading onto the
               fulcrum guides 21, the second godet roller 12 and the fulcrum guides 21 are moved
               to their respective winding positions. Further, the slidable component 45 is slid
               toward the base end side in the first direction, and the yarn separation guide 47
               is returned to the retreat posture.
 
            (Control of Suction Force of Suction)
[0056] During the above-described series of processes of yarn threading, the yarn threading
               robot 3 sucks and retains the yarns Y using the suction 42. In this regard, proper
               suction force changes depending on the element subjected to yarn threading, and there
               is a possibility that yarn threading is not successfully performed if the suction
               force of the suction 42 is constant. To deal with this, in the present embodiment,
               the electro-pneumatic regulator 37 is provided to an intermediate portion of the compressed
               air hose 7, so that the suction force of the suction 42 is adjustable by controlling
               the electro-pneumatic regulator 37 by the robot controller 102, as described above.
               The following will describe a specific example of the control of the suction force
               of the suction 42.
 
            [0057] FIG. 12 is a graph showing an example of the control of the suction force of the
               suction 42. In the present embodiment, as shown in FIG. 12, the robot controller 102
               controls the suction force of the suction 42 based on which of the processes of yarn
               threading is performed. The robot controller 102 stores, in advance, control data
               shown in FIG. 12 (suction force as a function of the processes of yarn threading).
               Based on the control data, the robot controller 102 controls the electro-pneumatic
               regulator 37 in a series of processes of yarn threading (a single set of processes
               of yarn threading) from the process of handing over the yarns Y to the suction to
               the process of yarn threading onto the bobbins B, which will be described later.
 
            [0058] In the first place, the robot controller 102 controls the electro-pneumatic regulator
               37 so as to generate a predetermined level of suction force in the suction 42. With
               this suction force, the yarns Y are passed from the aspirator 15 to the suction 42
               (handing over of the yarns Y). Thereafter, yarn threading onto the yarn regulating
               guide 16 is performed. When yarn threading is performed onto the yarn regulating guide
               16, the robot controller 102 controls the electro-pneumatic regulator 37 so that the
               suction force of the suction 42 is larger than the above predetermined level in the
               process of handing over of the yarns Y. This is because, unless the tension of the
               yarns Y is increased to some extent in the process of yarn threading into the guide
               grooves of the yarn regulating guide 16, the motions of the yarns Y tend to be unstable
               due to the contact with the yarn regulating guide 16, which may result in unsuccessful
               yarn threading.
 
            [0059] Subsequently, yarn threading onto the godet rollers 11 and 12 is performed. In this
               process, the robot controller 102 controls the electro-pneumatic regulator 37 so as
               to adjust the suction force of the suction 42 by increasing or decreasing the suction
               force, as needed, in accordance with the motion of the yarn threading unit 33. It
               should be noted that the increase or decrease of the suction force as above is not
               essential. Yarn threading onto the godet rollers 11 and 12 may be performed with the
               suction force equal to that in the process of yarn threading onto the yarn regulating
               guide 16.
 
            [0060] After yarn threading onto the godet rollers 11 and 12, yarn threading onto the pressing
               roller 46 and the yarn separation guide 47 is performed, in this order. Before yarn
               threading onto the pressing roller 46, the robot controller 102 controls the electro-pneumatic
               regulator 37 so as to decrease the suction force of the suction 42. This is because,
               if the suction force of the suction 42 is too large, large vibration is imparted to
               the sucked yarns Y by the suction 42, causing a possibility that the propagation of
               the vibration cannot be suppressed by the pressing roller 46. This may increase yarn
               swaying, leading to unsuccessful yarn threading onto the yarn separation guide 47.
 
            [0061] Subsequently, yarn threading onto the fulcrum guides 21 at the yarn threading positions
               is performed. In this process, the robot controller 102 controls the electro-pneumatic
               regulator 37 to adjust the suction force of the suction 42. As can be clearly seen
               from FIG. 11, in the process of yarn threading onto the fulcrum guides 21, it is necessary
               to increase the suction force of the suction 42 to minimize yarn swaying, in order
               to increase the success rate of yarn threading, because the yarns Y are inserted into
               the grooves 21a while coming into contact with the fulcrum guides 21. In this regard,
               however, if the suction force of the suction 42 is increased too much to minimize
               yarn swaying, friction between the yarns Y and the yarn separation guide 47 becomes
               too high, which may cause yarn breakage. For this reason, as described above, the
               suction force in the process of yarn threading onto the fulcrum guides 21 is adjusted
               to minimize both yarn breakage and yarn swaying, taking the friction between the yarns
               Y and the yarn separation guide 47 into consideration. This adjustment increases the
               success rate of yarn threading onto the fulcrum guides 21. FIG. 12 shows the case
               in which the suction force of the suction 42 is slightly increased in the process
               of yarn threading onto the fulcrum guides 21, by way of example.
 
            [0062] After the yarn threading onto the fulcrum guides 21, the fulcrum guides 21 are moved
               from the yarn threading positions to the winding positions. Regardless of whether
               the fulcrum guides 21 have been moved from the yarn threading positions to the winding
               positions, after the yarn threading onto the fulcrum guides 21, the yarn threading
               unit 33 is moved to the yarn threading position for yarn threading onto the bobbins
               B attached to the bobbin holder 24. At this position, yarn threading onto the bobbins
               B is performed. In the process of yarn threading onto the bobbins B, the robot controller
               102 controls the electro-pneumatic regulator 37 so that the suction force of the suction
               42 is the largest in a single set of processes of yarn threading. Increase in the
               suction force increases the tension of the yarns Y. This reduces the possibility that
               yarn threading onto the bobbins B is failed due to slack of the yarns Y.
 
            [0063] Now, proper suction force of the suction 42 can change depending on the material
               and diameter of the yarns Y, production conditions such as the spinning-out speed
               of the yarns Y, and the like. Accordingly, in the present embodiment, there are plural
               sets of control data corresponding to various types of yarns Y and/or production conditions
               (an example of such a set of data is indicated by broken lines in FIG. 12). For example,
               when an operator inputs the type of the yarns Y and/or production conditions through
               the operation unit 4a of the centralized controller 4, information regarding the yarn
               type and/or the production conditions is transmitted from the centralized controller
               4 to each robot controller 102. Then, the robot controller 102 selects a set of control
               data corresponding to the type of the yarns Y and/or the production conditions, and
               controls the suction force of the suction 42 based on the selected control data. It
               should be noted that the manner of the control of the suction force of the suction
               42 does not have to be changed depending on the type of the yarns Y and/or the production
               conditions.
 
            (Advantageous Effects)
[0064] As described above, the yarn threading robot 3 of the present embodiment includes
               the robot controller 102 configured to control the suction force of the suction 42
               (sucking retaining unit). Due to this, it is possible to stably perform yarn threading
               by increasing or decreasing the suction force as needed.
 
            [0065] Furthermore, in the present embodiment, the suction 42 is configured so that compressed
               air (compressed fluid) is supplied to the suction 42 and thereby a suction force corresponding
               to the pressure of the compressed air is generated; and the robot controller 102 is
               configured to control the suction force of the suction 42 by controlling the pressure
               of the compressed air supplied to the suction 42. In the above arrangement, the suction
               force of the suction 42 can be easily increased or decreased merely by adjusting the
               pressure of the compressed air.
 
            [0066] Furthermore, in the present embodiment, the yarn threading robot further includes
               the electro-pneumatic regulator 37 (pressure adjuster) configured to adjust the pressure
               of the compressed air, the regulator 37 provided to the compressed air hose 7 (path)
               through which the compressed air is supplied to the suction 42; and the robot controller
               102 is configured to control the suction force of the suction 42 by controlling the
               operation of the electro-pneumatic regulator 37. Because the electro-pneumatic regulator
               37 configured to adjust the pressure of the compressed air is provided to the yarn
               threading robot 3, the distance between the electro-pneumatic regulator 37 and the
               suction 42 is short, which provides quick responsivity in the control of the suction
               force.
 
            [0067] Furthermore, in the present embodiment, the electro-pneumatic regulator 37 functions
               as the pressure adjuster, as described above. The use of the electro-pneumatic regulator
               37 as the pressure adjuster allows the pressure of the compressed air to be adjusted
               in a substantially non-step manner, which allows minute control of the suction force
               of the suction 42.
 
            [0068]  Furthermore, in the present embodiment, the robot controller 102 is configured to
               change the suction force of the suction 42 in a single set of processes of yarn threading.
               Even in a single set of processes of yarn threading, proper suction force can change
               depending on which of the processes is performed (for example, depending on the element
               onto which yarn threading is performed). In the above-mentioned arrangement, it is
               possible to deal with the case where the proper suction force changes within a single
               set of processes of yarn threading, thereby to enable more stable yarn threading.
 
            [0069] Furthermore, in the present embodiment, the robot controller 102 is configured to
               control the suction force of the suction 42 so that the suction force is the largest
               in a process of yarn threading onto the bobbins B among the single set of processes
               of yarn threading. Generally, in the process of yarn threading onto the bobbins B,
               it is necessary to thread yarns Y into respective slits of the bobbins B. Due to this,
               if the suction force is insufficient in the process of yarn threading onto the bobbins
               B, the tension of the yarns Y may be too low, resulting in unsuccessful yarn threading
               into the slits. In the above-mentioned arrangement, the suction force is adjusted
               so that the suction force in the process of yarn threading onto the bobbins B is the
               largest in the single set of processes of yarn threading. This makes it easier to
               thread the yarns Y into the slits, and enables reliable yarn threading onto the bobbins
               B.
 
            [0070] Furthermore, in the present embodiment, the robot controller 102 is configured to
               change the suction force of the suction 42 based on the type of the yarns Y wound
               by the spun yarn take-up apparatus 2 and/or based on production conditions. Proper
               tensions in the processes of yarn threading may differ depending on the type of the
               yarns Y and/or production conditions. Even in such a case, each process of yarn threading
               is performed with a tension suitable for subject yarns Y by changing the suction force
               depending on the type of the yarns Y and/or production conditions.
 
            (Other embodiments)
[0071] Although an embodiment of the present invention has been described, the present invention
               is not limited to the above-mentioned embodiment and can be suitably changed within
               the scope of the present invention as described below.
 
            [0072] For example, in the embodiment above, the electro-pneumatic regulator 37 functioning
               as the pressure adjuster is provided to the part of the compressed air hose 7, the
               part being provided to the yarn threading robot 3. However, the position at which
               the electro-pneumatic regulator 37 is provided is not limited to this. For example,
               the electro-pneumatic regulator 37 may be provided to a part of the compressed air
               hose 7, the part being not provided to the yarn threading robot 3. Furthermore, as
               the pressure adjuster, an electrically-controlled flow regulating valve may be provided,
               for example, instead of the electro-pneumatic regulator 37.
 
            [0073] In the embodiment above, the robot controller 102 controls the suction force of the
               suction 42 based on which of the processes of yarn threading is performed. However,
               arrangements other than the above are also possible. For example, various sensors
               configured to detect the position and/or posture of the robotic arm 32 may be provided,
               and the robot controller 102 may control the suction force of the suction 42 based
               on values output from these sensors.
 
            [0074] In the embodiment above, the robot controller 102 stores in advance control data
               regarding the suction force of the suction 42, and controls the suction force based
               on the stored control data. However, it is not essential for the robot controller
               102 to store such control data in advance. For example, a sensor configured to detect
               the tension of the yarns Y may be provided, and the robot controller 102 may control
               the suction force of the suction 42 based on a value output from the sensor.
 
            [0075] In the embodiment above, the yarn threading robot 3 is arranged to hang down from
               the guide rails 35, however, the yarn threading robot 3 does not have to hang down.
               For example, the yarn threading robot 3 may be arranged to travel on the floor.
 
            [0076] In addition to the above, the configuration of the yarn threading unit 33 is not
               limited to that of the above embodiment. For example, the yarn threading unit 33 may
               just include the suction 42, the yarn convergence guide 43, and the cutter 44, when
               the winding unit 13 includes the pressing roller 46, the yarn separation guide 47,
               and a driving source configured to thread the yarns Y, which have been threaded onto
               the yarn separation guide 47, onto the fulcrum guides 21.
 
            ITEMS OF DISCLOSURE
[0077] 
               
               
                  - 1. A yarn threading robot configured to perform yarn threading onto a spun yarn take-up
                     apparatus while sucking and retaining a yarn by a sucking retaining unit, the spun
                     yarn take-up apparatus being configured to wind the spun-out yarn onto a bobbin while
                     traversing the yarn to form a package, the yarn threading robot comprising
                     a controller configured to control a suction force of the sucking retaining unit. 
                  - 2. The yarn threading robot according to 1, wherein:
                     
                     
the sucking retaining unit is configured so that compressed fluid is supplied to the
                        sucking retaining unit and thereby a suction force corresponding to a pressure of
                        the compressed fluid is generated; and
                     the controller is configured to control the suction force of the sucking retaining
                        unit by controlling the pressure of the compressed fluid supplied to the sucking retaining
                        unit.
                   
                  - 3. The yarn threading robot according to 2, further comprising
                     a pressure adjuster configured to adjust the pressure of the compressed fluid, the
                     pressure adjuster provided to a path through which the compressed fluid is supplied
                     to the sucking retaining unit, wherein
                     the controller is configured to control the suction force of the sucking retaining
                     unit by controlling operation of the pressure adjuster. 
                  - 4. The yarn threading robot according to 3, wherein the pressure adjuster is an electro-pneumatic
                     regulator.
 
                  - 5. The yarn threading robot according to any one of 1 to 4, wherein the controller
                     is configured to change the suction force of the sucking retaining unit in a single
                     set of processes of yarn threading.
 
                  - 6. The yarn threading robot according to 5, wherein the controller controls the suction
                     force of the sucking retaining unit so that the suction force in a process of yarn
                     threading onto the bobbin is the largest in the single set of processes of yarn threading.
 
                  - 7. The yarn threading robot according to any one of 1 to 6, wherein the controller
                     changes the suction force of the sucking retaining unit based on a type of yarn wound
                     by the spun yarn take-up apparatus and/or based on a production condition.