Title of Invention

A FIBER BUNDLE COLLECTING DEVICE

Abstract

A fiber bundle collecting device is equipped with a send-out portion provided on the downstream side of a final send-out roller pair of a drafting device and a suction portion 5 equipped with a suction hole provided so as to extend toward the upstream side at least with respect to a direction in which the fiber bundle moves with respect to a nip point of the send-out portion. The fiber bundle collecting device is equipped with an air-permeable member for forming the send-out portion and being rotated along the suction portion 5, and is adapted to collect the fiber bundle drafted by the drafting device. The suction portion 5 is connected to a duct (44) through a connection pipe (48), and the duct (44) is connected to a plurality of suction devices (45) for keeping negative pressure inside the duct (44).

Full Text

FIBER BUNDLE COLLECTING DEVICE AND SPINNING MACHINE BACKGROUND OF THE INVENTION Field of the invention: The present invention relates to a fiber bundle collecting device and a spinning machine, and more specifically, to a fiber bundle collecting device arranged, for example, on the downstream side of a drafting device (drafting part) of a spinning frame and adapted to collect a fiber bundle drafted by the drafting device, and a spinning machine equipped with the fiber bundle collecting device. Description of the Related Art: Fig. 7 shows a disclosed example of a spinning machine equipped with a fiber bundle collecting device of this type (see, for example, JP 2000-73224 A). A spinning frame is equipped with a plurality of spinning stations 71 on both sides of the machine base, and the fiber bundle collecting device is equipped with suction profiles 72 and 73 having a plurality of suction slits (suction holes) provided in correspondence with the spinning stations 71 and exerting sucking action on a fiber bundle drafted by a drafting device. The suction profiles 72 and 73 are respectively connected to suction devices 76 and 77 through suction pipes 74 and 75. Each of the suction devices 76 and 77 is equipped with a fan 79 driven by a motor 78. In this fiber bundle collecting device, the suction devices 76 and 77 are respectively provided for a fixed number of spinning stations 71, so that the difference in suction pressure acting on the suction slits of the individual spinning stations 71 is reduced, thereby facilitating a reduction in the difference in the quality of thread obtained by spinning to a permissible level. Further, according to JP 2000-73224 A, to monitor vacuum state and thread quality, pressure measuring devices are respectively 1 provided for the suction pipes 74 and 75, and whenever a malfunction occurs, the operation of the relevant machine portion is stopped. As compared with a construction in which a suction channel common to all the spinning stations is maintained in a vacuum state by a single vacuum creating fan and in which the fiber bundle collecting device is connected to this suction channel, in the device as disclosed in JP 2000-73224 A, it is easier to reduce the difference in the quality of thread obtained by spinning with each of the spinning stations 71 to a permissible level. However, the number of suction devices 76, 77 for imparting sucking action to the suction profiles 72, 73 of each of the spinning stations 71 in a group is restricted to one, so that when one suction device is out of order, no sucking action is generated for the suction profile assigned to that suction device. As a result, when spinning is continued, the difference in quality between the thread obtained by the spinning station 71 under no sucking action and the thread obtained by the spinning station 71 under sucking action exceeds permissible limits. According to the above publication, the above problem is coped with by arranging pressure measuring devices respectively for the suction pipes 74 and 75 and stopping the relevant machine portion at the time of a malfunction. However, the publication makes no mention of a mechanism for stopping the relevant machine portion. Further, when the spinning frame is not of a so-called single-spindle-drive type, the provision of the mechanism for stopping the relevant machine portion would entail a rather complicated mechanism, which means an increase incest is inevitable. Further, in the device as disclosed in JP 2000-73224 A, a single suction pipe 74, 75 is connected to suction profiles 72, 73 each corresponding to eight spinning stations 71. As the number of spinning stations 71 receiving sucking action from one suction profile 72, 7 3 increases, the difference in sucking action between the spinning stations 71 which are closer to the suction pipe 74, 75 and the spinning stations 71 which are farther therefrom increases. As a result, variation in quality is liable to be generated among the threads obtained by spinning by the different spinning stations 71. In the device disclosed in JP 2000-73224 A, the suction pipes 74 and 75 are directly connected to the suction devices 76 and 77, so that it is rather difficult to increase the number of suction pipes 74, 75 connected to the suction devices 76, 77 in order to reduce the number of spinning stations 71 receiving sucking action from one suction profile 72, 73. Further, coping with an increase in the number of suction pipes by increasing the number of suction devices without increasing the number of suction pipes connected to one suction device results in an increase in cost. SUMMARY OF THE INVENTION The present invention has been made in view of the above problem in the prior art. It is an object of the present invention to provide a fiber bundle collecting device for a spinning machine in which, even when abnormality is generated in any suction device, it is possible to maintain, within a permissible range, the difference in quality between the thread obtained by spinning by the spindle unit (spinning station) under the sucking action of that suction device and the thread obtained by spinning by the other spindle units. According to the present invention, there is provided a fiber bundle collecting device for collecting a fiber bundle drafted by a drafting part of a spinning machine, including: a send-out portion provided on the downstream side of a final send-out roller pair of a drafting part and equipped with a nip roller; a suction portion having a sliding surface equipped with a suction hole provided so as to extend toward the upstream side with respect to a direction in which the fiber bundle moves with respect to a nip point of the send-out portion; and an air-permeable apron forming the send-out portion and rotated while in contact with the sliding surface, the suction portion having a plurality of suction holes formed respectively in correspondence with a plurality of spindle units, the plurality of suction holes communicating with a common duct, with the duct being maintained at negative pressure by a plurality of suction devices. Thus, in the present invention, sucking action is generated in a plurality of suction holes of the suction portion due to the negative pressure in the duct. The duct is maintained at negative pressure by a plurality of suction devices, so that, even if some suction devices become out of order and are stopped, the quality of the thread obtained by spinning is maintained within the permissible range due to the negative pressure generated by the remaining suction devices. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic plan view showing an arrangement of suction devices and a duct in an embodiment of the present invention; Fig. 2 is a schematic side view, partly in section, showing a drafting device and a fiber bundle collecting device; Fig. 3 is a partial schematic diagram showing a relationship between suction portions and bottom nip rollers; Fig. 4a is a partial schematic view of the fiber bundle collecting device as seen from the front side with respect to a direction in which the fiber bundle moves; Fig. 4b is a front view of a rotation shaft; Fig. 5 is a partial enlarged view of Fig. 2; Fig. 6 is a partial perspective view of a connection pipe; and Fig. 7 is a schematic plan view of a conventional device. DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will now be described with reference to Figs. 1 through 6. Fig. 1 is a schematic plan view showing a relationship among a duct of a fiber bundle collecting device, suction devices, and suction portions, and Fig. 2 is a schematic side view, partly in section, showing on one side of a drafting device. Fig. 3 is a partial schematic view of the drafting device, with the top roller side being omitted, showing a relationship between the suction portions and bottom nip rollers of the fiber bundle collecting device. Fig. 4a is a schematic view of the fiber bundle collecting device as seen in a fiber-drawing-out direction at a nipping point (as seen from the front side with respect to a fiber bundle moving direction in the drafting device). As shown in Fig. 2, a drafting device 11 as a draft part is of a three-line construction equipped with a front bottom roller 12, a middle bottom roller 13, and a back bottom roller 14. The front bottom roller 12 is supported at a predetermined position with respect to a roller stand 15 constituting a machine base frame, and the middle and back bottom rollers 13 and 14 are supported through the intermediation of support brackets 13a and 14a secured to the roller stand 15 so as to allow position adjustment in the longitudinal direction. The support brackets 13a and 14a are fastened to predetermined positions by means of bolts passed through an elongated hole formed in the roller stand 15 and nuts (all not shown) . A bottom apron 16 is wrapped around a bottom tenser 17 and the middle bottom roller 13. Supported by a weighting arm 18 through the intermediation of top roller support members are a front top roller 19, a middle top roller 20, and a back top roller 21 at positions respectively corresponding to the front bottom roller 12, the middle bottom roller 13, and the back bottom roller 14. Each of the top rollers 19 through 21 is supported in a two-spindle unit. The front bottom roller 12 and the front top roller 19 constitute the pair of final delivery rollers of the drafting device 11. On the weighting arm 18, there is arranged a lever 18a so as to be rotatable to a pressurizing position and a releasing position. In the condition in which the lever 18a is arranged at the pressurizing position where it abuts the frame 18b of the weighting arm 18 shown in Fig. 2, a lock state is maintained in which the top rollers 19 through 21 supported by the weighting arm 18 are in the pressurizing position (spinning position) in which they are pressurized toward the bottom rollers 12, 13, and 14. In the condition in which the lever 18a has been rotated from the position shown in Fig. 2 to the upper, releasing position, the lock state is canceled. As shown in Fig. 2, a fiber bundle collecting device 30 is arranged on the downstream side of the pair of final delivery rollers of the drafting device 11. The fiber bundle collecting device 30 is equipped with a delivery portion 31, suction pipes 32 and 33 as a suction portion S, and an air-permeable apron 34 as an air-permeable member. The delivery portion 31 is composed of a bottom nip roller 35a formed on a rotation shaft 35 arranged parallel to the front bottom roller 12 and a top nip roller 31a pressurized against the bottom top roller 35a through the intermediation of the air-permeable apron 34. As shown in Fig. 4a, in the fiber bundle collecting device 30 of this embodiment, the top nip roller 31a is, like the top rollers 19 through 21 of the drafting device 11, supported in every two spindles by the weighting arm 18 through the intermediation of a support member 36 (shown in Fig. 2 and Fig. 5) . Note that, in this embodiment, the support member 36 is formed integrally with the support member of the front top roller 19. On the other hand, on the bottom side of the fiber bundle collecting device 30, half the spindles arranged between the roller stands 15 of the drafting device 11 which are adjacent to each other, i.e., four spindles, constitute one unit. As shown in Fig. 3, at the middle position of the roller stands 15 arranged at predetermined intervals in the longitudinal direction of the machine base, a support arm 38 is arranged in a state in which its base end is supported by a support beam 37 extending in the longitudinal direction of the machine base, and a rotation shaft 35 is supported between the roller stand 15 and the support arm 38. As shown in Fig. 4b, the rotation shaft 35 is formed in a predetermined length corresponding to a plurality of spindles (four spindles in this embodiment), and a bearing 39 is secured to either end thereof. Then, the bearings 39 are fitted into end plugs 40, and, as shown in Fig. 4a, the end plugs 40 are supported in the engagement portions 40a by support portions 15a and 38a provided on the roller stand 15 and the support arm 38, whereby the rotation shaft 35 is rotatably supported between the roller stand 15 and the support arm 38. The support portions 15a and 38a are formed so as to be capable of supporting two end plugs 40 mounted to the end portions of the adjacent rotation shafts 35. The support portion 15a is formed by a block fixed to the roller stand 15, and has engagement recesses extending obliquely upwards on the front side of the machine base. The support portion 38a also has an engagement recess extending obliquely upwards on the front side of the machine base. Then, the end plug 40 has an engagement portion 40a capable of being engaged with the engagement recesses, and is formed so as to be capable of being snapped in place with a single motion with respect to the support portions 15a and 38a in the engagement portion 40a. The rotation shaft 35 has at its longitudinal center a gear 41 which is arranged so as to be capable of rotating integrally with the rotation shaft 35. As shown in Fig. 3, the front bottom roller 12 has a gear portion 12a at a position opposed to the gear 41. Further, an intermediate gear 43 in mesh with the gear portion 12a and the gear 41 is rotatably supported by a support arm 42 whose base end is fixed to the support beam 37 like the support arm 38. That is, the torque of the front bottom roller 12 is transmitted to the rotation shaft 35 by way of the gear portion 12a, the intermediate gear 43, and the gear 41. As shown in Figs. 1 and 2, in the machine base of the spinning frame, ducts 44 for the fiber bundle collecting device 30 are arranged so as to extend in a longitudinal direction thereof (in a direction perpendicular to the plane of Fig • 2 ) . As shown in Fig. 1, a plurality of ducts 44 are provided so as to extend in the longitudinal direction of the machine base of the spinning frame. In this embodiment, the length of each duct 44 is such that it corresponds to 24 spindle units on one side and 48 spindle units on both sides. A plurality of (three in this embodiment) suction devices 45 for maintaining negative pressure in each duct 44 are connected to each duct 44 through pipes 46. That is, in this embodiment, one suction device 45 is provided for one unit, which is composed of 16 spindle units. The suction devices 45 are composed of fan motors in which fans 47a are driven by motors 47. As shown in Fig. 2, the ducts 44 are arranged on the upper rear side of the drafting device 11 and at the center of the machine base of the spinning machine, and the suction devices 45 are arranged below the ducts 44. As shown in Fig. 1, four suction portions S are provided for every four spindle units so as to extend parallel to the ducts 44, and connected to the ducts 44 through connection pipes 48. Each connection pipe 48 has at some midpoint thereof a bellows portion 49 (shown in Fig. 2 alone) . In Fig. 1, the suction pipes 32 and 33 are collectively shown as the suction portions S, and suction holes formed in each of the suction pipes 32 and 33 and described below are indicated by broken-line circles. As shown in Fig. 6, in the forward end portion of the connection pipe 48, there are formed engagement holes 48a and 48b to which the suction pipes 32 and 33 are detachably mounted. In addition, to the right and left sides of the connection pipe 48, the first end portions of the suction pipes 32 and 33 are detachably mounted, and the second end portions of the suction pipes 32 and 33 are engaged with the end plug 40. Further, an engagement hole 40b where the bearing 39 is engaged is formed on the end plug 40. Fig. 6 is a partial schematic perspective view showing a state in which the suction pipes 32 and 33 are mounted to one side of the connection pipe 48. As shown in Fig. 3, the suction pipe 32 has a sliding surface 32b having slit-like suction holes 32a extending on the upstream side with respect to the direction in which the fiber bundle ( fleece) F moves with the nip point of the bottom nip roller 35a being therebetween. The suction pipe 33 has a sliding surface 33b having slit-like suction holes 33a extending on the downstream side. Then, as shown in Figs. 3 and 5, the suction pipe 32 is arranged so as to be on the upstream side of the nip point of the bottom nip roller 35a with respect to the fiber bundle moving direction, and the suction pipe 33 is arranged so as to be on the downstream side thereof. Note that, in Fig. 3, the air-permeable apron 34 is indicated by a chain line so that the suction holes 32a and 33a may be easily seen. The suction pipes 32 are formed in a configuration such that they can guide the air-permeable aprons 34 so as to bring them near the nip points of the front bottom roller 12 and the front top rollers 19. The suction pipes 33 are arranged such that the fiber bundles F sent out from the air-permeable aprons 34 are deflected by a certain fleece angle. The term fleece angle means the angle made by the segment connecting the center of curvature of the arcuate surface along which the fiber bundle F (fleece) having passed the nip point is guided to the draw-out position and the nip point and the segment connecting the center of curvature and the draw-out point for the fiber bundle F. The air-permeable aprons 34 are wrapped so as to come into contact partly with the suction pipes 32 and 33 and partly with the bottom nip roller 35a and to rotate while sliding on the slide surfaces 32b and 33b as the bottom nip rollers 35a rotate. In this embodiment, the air-permeable aprons 34 are formed of woven fabric which can secure appropriate air-permeability. As shown in Figs. 2, 4a, etc., in the vicinity of the lower portion of each suction pipe 33, there is arranged the forward end portion of a suction nozzle 50 of a single type pneumatic device adapted to suck the fiber bundle F sent out from the drafting device 11 at the time of thread breakage. The base end of the suction nozzle 50 is connected to the suction duct 51 common among all the spindles. Next, the operation of the device constructed as described above will be described. When the spinning frame is operated, the fiber bundle F passes between the bottom rollers 12 through 14 and the top rollers 19 through 21 of the drafting device 11 to be thereby drafted, and is then guided to the fiber bundle collecting device 30. The top nip roller 31a of the delivery portion 31 is rotated at as speed somewhat higher than the surface velocity of the front bottom roller 12 and that of the front top roller 19; after passing the nip point of the delivery portion 31 under appropriate tension, the fiber bundle F is deflected and moves downstream while undergoing twisting. Further, the sucking action of the ducts 44 are exerted on the suction pipes 32 and 33 through the connection pipes 48, and the sucking action of the suction holes 32a and 33a formed on the slide surfaces 32b and 33b is exerted on the fiber bundles F through the air-permeable aprons 34. Then, the fiber bundles F move while being attracted and collected at positions corresponding to the suction holes 32a and 33a. Since the suction holes 32a and 33a exist respectively on the upstream side and the downstream side of the nip points of the send-out portions 31, the fiber bundles F move while being collected under the sucking action even after passing the nip points. As a result, fiber separation at both ends of each fiber bundle F after passing the nip point is restrained to suppress generation of fluff and waste cotton, thereby achieving a substantial improvement in terms of thread quality. Each duct 44 is maintained at negative pressure by a plurality of (three) suction devices 45. Thus, even if one of the suction devices 45 is stopped due to abnormality (failure) generated therein, the negative pressure inside the duct 44 is maintained at a predetermined level by the action of the other suction devices 45, thereby securing the sucking action of the suction holes 32a and 33a for collecting the fiber bundle F. If spinning is continued under the absence of the sucking action, the thread quality deteriorates. However, unlike the conventional device, the device of this embodiment is capable of securing the sucking action of the suction holes 32a and 33a even if one of the suction devices 45 stop due to failure, thus restraining a deterioration in thread quality. This embodiment provides the following advantages. a) The suction pipes 32 and 33 equipped with the suction holes 32a and 33a, which exert sucking action on the fiber bundles F after drafting, in correspondence with each of the spindle units, are connected to the ducts 44 through the connection pipes 48, and each duct 44 is maintained at negative pressure by a plurality of suction devices 45. Thus, unlike the conventional device, when some suction devices 45 are stopped due to abnormality, this embodiment can secure the sucking action of the suction holes 32a and 33a due to the negative pressure generated by the remaining suction devices 45, thereby maintaining the quality of the thread obtained by spinning within permissible limits. b) A plurality of ducts 44 are provided so as to extend along the longitudinal direction of the machine base of the spinning machine. As compared with a construction in which a single duct 44 is arranged so as to extend in the longitudinal direction of the machine base of the spinning machine, the mounting of the ducts 44 are easier to perform. Further, when a pillar is provided at some midpoint of the machine base of the spinning machine, interference of the ducts 44 with the pillar is easily avoided. c) In a construction in which a single suction pipe 32, 33 exerts sucking action on the fiber bundles F of a number of spindle units, a difference in sucking action between the suction hole 32a, 33a which is closer to the connection pipe 48 and the suction hole 32a, 33a which is farther therefrom becomes large. Further, in addition to the difference in sucking action between the spindle units, an increase in the length of a single suction pipe 32, 33 involves a deterioration in the operability for mounting and dismounting with respect to the machine base and for maintenance, so that it is preferable for a single suction pipe 32, 33 to have suction holes 32a, 33a for four spindles units. In that case, the number of connection pipes 48 increases. However, the connection pipes 48 are connected not to the suction devices 45 but to the ducts 44. Thus, even if the number of connection pipes 48 increases, it is possible to connect the suction pipes 32, 33 and the ducts 44 easily under the same condition, so that there is little variation in the quality of the thread obtained by spinning by each spindle unit. d) Ducts 44 dedicated to the fiber bundle collecting device 30 are provided independently of a pneumatic duct 51. Thus, it is possible to maintain a predetermined negative pressure in the ducts 44 without involving an increase in size of the suction devices 45. e) The ducts 44 are arranged on the rear side and above the drafting device 11 and at the center of the machine base of the spinning machine, and the connection pipes 48 are arranged so as to extend above the bottom rollers 12 through 14 . Thus, in a spinning machine in which the pneumatic duct 51 is provided so as to extend in the longitudinal direction of the machine base of the spinning machine, it is easy to secure the arrangement positions for the ducts 44. Further, the connection pipes 48 connecting the ducts 44 and the suction pipes 32, 33 do not easily interfere with other members, whereby the mounting operation and the maintenance operation are facilitated. f) The suction pipes 32, 33 are mounted symmetrically on both sides of each connection pipe 48, so that assuming that the same number of suction holes 32a, 33a are provided, the difference in sucking action between the suction holes 32a, 33a is diminished as compared with the case in which the suction pipes 32 and 33 are mounted to one side of each connection pipe 48. Further, the operation of replacing the air-permeable aprons 34 is facilitated. g) The collecting effect due to the suction holes 33a provided on the downstream side of the nip points is propagated to some extent to the upstream side of the nip points, and the divergence of the fiber bundles F until the nip points are reached is restrained. As a result, the collecting effect is further improved. The above-described embodiment should not be construed restrictively. For example, the following construction is also possible. An abnormality detecting means for detecting any abnormality in the suction devices is provided. On the basis of an abnormality detection signal from the abnormality detecting means, a suction device in which some abnormality has been generated is stopped. Further, it is also possible to adopt an arrangement in which the other, normal suction devices connected to the duct to which the suction device with abnormality is connected are driven so as to be enhanced in their performance. For example, as indicated by the chain lines in Fig. 1, each suction device 45 is equipped with an abnormality detecting sensor 52 as abnormality detecting means for the motor 47. The abnormality detecting sensor 52 is composed of a rotating speed sensor for the driving shaft of the motor 47, for example. Further, each motor 47 is constructed so as to be capable of being controlled independently by a control device (not shown) . Then, on the basis of the abnormality detection signal from the abnormality detecting sensor 52, the control device stops the suction device 45 in which abnormality has been generated, and performs control so as to enhance the performance of the other suction devices 45 connected to the duct 44 to which that suction device 45 is connected. Then, the suction device 45 in which abnormality has been generated is repaired when doffing is stopped. If abnormality has been generated in any suction device 45, the negative pressure in the duct 44 is maintained within permissible limits even if that suction device 45 is stopped, making it possible to continue spinning until a predetermined doffing time with the quality of the thread obtained by spinning being stable. If a construction is adopted in which control is possible for each of the motors 47 connected to the same duct 44 instead of the construction in which each motor 47 can be independently controlled. it is possible to enhance the performance of the other suction devices 45 when abnormality is generated in any suction device 45. For example, when the motors 47 are driven by inverters, an inverter is provided for each of the motors 47 connected to the same duct 44. In this case, simplification in control and construction is achieved as comparedwith the case in which each motor 47 is controlled independently. It is also possible to adopt an arrangement in which abnormality detecting means for detecting abnormality in the suction devices 45 is provided to stop the spinning by all the spindle units on the basis of an abnormality detection signal from the abnormality detecting means. For example, as indicated by chain lines in Fig. 1, an abnormality detecting sensor 52 as abnormality detecting means for the motor 47 is provided for each suction device 45. Then, on the basis of the abnormality detection signal from the abnormality detecting sensor 52, the control device for controlling the operation of the spinning machine starts control for stopping the operation of the spinning machine. After the operation of the spinning machine has been stopped, the suction device 45 with abnormality is repaired. In this case, when abnormality is generated in any suction device 45, the spinning by all the spindle units is stopped on the basis of an abnormality detection signal from the abnormality detecting means, so that it is possible to prevent the operation of the spinning machine from being continued for a long time in an abnormal state. Further, it is possible to repair the suction device with abnormality at an early stage. In the case of a so-called single-spindle-drive type spinning frame in which the spindles of the spindle units as a spinning frame are independently driven by individual motors, it is also possible to adopt an arrangement in which the driving of the spindles of the spindle units corresponding to the suction pipes 32, 33 receiving sucking action from the duct 44 to which the suction device 45 with abnormality is connected. Then, spinning is continued with the other spindle units until a predetermined doffing time. In this case, the number of spindle units whose spinning is stopped during taking-up is reduced as compared with the case in which the spinning by all the spindle units is stopped. The length of each duct 44 does not necessarily correspond to 24 spindle units on one side and 48 spindles on both sides; it may correspond to an appropriate number of spindle units. In that case, the length corresponding to the number of spindle units which is a multiple of eight is preferable. Instead of providing a plurality of ducts 44 so as to extend in the longitudinal direction of the machine base of the spinning machine, it is also possible to provide only one duct extending over the entire length of the machine base of the spinning machine base. The position of the ducts 44 is not restricted to the rear side and above the drafting device 11. It is also possible to provide them behind or on the rear side and below the drafting device 11. Instead of the ducts 44 shared by the suction pipes 32, 33 arranged on both sides of the spinning frame, it is also possible to arrange the ducts in two rows, for the right and left sides, extending in the longitudinal direction of the machine base of the spinning machine. Instead of the construction in which the rotation shafts 35 and the suction pipes 32, 33 are arranged such that four spindle units constitute one unit, it is also possible to adopt a construction inwhich the number of spindle units (e.g., eight) between the adjacent roller stands 15 corresponds to one unit, or a construction in which two spindle units constitute one unit. Further, it is not always necessary for all the units to have the same number of spindle units; it is also possible for the numbers of spindle units between the adjacent roller stands 15 to differ from each other (e.g., six and two), thus providing two kinds of units in correspondence therewith. Instead of forming the suction pipes 32, 33 as separate members, it is also possible to integrate the two suction pipes 32, 33, with the side opposed to the top nip roller 31a being arcuate. It is also possible for the suction pipes 32, 33 to be formed so as to be closed at the end portions on the side opposing the connection pipes 48. In this case, it is not necessary for the end plugs 40 to hermetically seal the end portions of the suction pipes 32, 33, and it is only necessary to provide engagement portions to be engaged with the end portions of the suction pipes 32, 33, thereby facilitating the production. Instead of forming the air-permeable aprons 34 of woven fabric or knitted fabric, it is also possible to form the air-permeable aprons by perforating resin belts formed of rubber or elastic resin. It is also possible for the suction pipes 32, 33 forming the suction portion to be formed integrally with the connection pipes 48. Instead of the construction in which the suction holes 32a, 33a are provided on the upstream side and the downstream side with respect to the nip points of the fiber bundles F, it is also possible to adopt a construction in which the suction holes 32a are provided only on the upstream side with respect to the nip points. In this case, the manufacturing and mounting methods can be substantially the same by using suction pipes 33 with no suction holes 33a. Further, it is also possible to eliminate the suction pipes 33 and to wrap the air-permeable aprons 34 between the suction pipes 32 and the bottom nip rollers 35a. As an arrangement for driving the air-permeable aprons 34, the following construction may be adopted. The suction pipes 32, 33 and the bottom nip rollers 35a are eliminated, and suction pipes egg-shaped in section are provided, with suction holes being formed at predetermined positions in the suction pipes and with the air-permeable aprons 34 being slidably wrapped around the outer peripheries of the suction pipes. Then, the top nip rollers 31a is enabled to be positively driven, and driven while being in press contact with the air-permeable aprons 34, thus driving the air-permeable aprons 34. The construction of the suction devices is not restricted to the one in which the fans 47a are driven by the motors 47. For example, it is also possible to use a pressure reducing pump (vacuum pump) . The vacuum pump may be a rotary type pump or a reciprocating type pump. As the pneumatic device, it is also possible to adopt a flute-type construction instead of a single nozzle type one. The present invention is applicable not only to the drafting device of a spinning frame but also to the drafting devices of other types of spinning machines. As described in detail above, in accordance with the present invention, even when abnormality is generated in any one of the suction devices, it is possible to maintain, within permissible limits, the difference in quality between the thread obtained by spinning by the spinning spindle units (spindle stations) under the sucking action of that suction device and the thread obtained by spinning by the other spinning spindle units. WHAT IS CLAIMED IS: 1. A fiber bundle collecting device for collecting a fiber bundle drafted by a drafting part of a spinning machine, comprising: a send-out portion provided on the downstream side of a final send-out roller pair of the drafting part and equipped with a nip roller; a suction portion having a sliding surface equipped with a suction hole provided so as to extend toward the upstream side with respect to a direction in which the fiber bundle moves with respect to a nip point of the send-out portion; and an air-permeable apron forming the send-out portion and rotated in contact with the sliding surface, the suction portion having a plurality of suction holes formed respectively in correspondence with a plurality of spindle units, the plurality of suction holes communicating with a common duct, with the duct being maintained at negative pressure by a plurality of suction devices. 2 . A fiber bundle collecting device according to claim 1, wherein the suction portion has a plurality of suction pipes respectively having a plurality of suction holes, and a plurality of connection pipes respectively connecting these suction pipes to the duct. 3. A fiber bundle collecting device according to claim 1 or 2, wherein the sliding surface of the suction portion further includes a suction hole provided so as to extend toward the downstream side with respect to a direction in which the fiber bundle moves with respect to the nip point of the send-out portion. 4 . A fiber bundle collecting device according to any one of claims 1 to 3, wherein a plurality of ducts are provided along a longitudinal direction of a machine base of the spinning machine. 5 . A fiber bundle collecting device according to any one of claims 1 to 4, further comprising abnormality detecting means for detecting any abnormality in the plurality of suction devices, when the abnormality detecting means detects abnormality in any one of the suction devices, the suction device with abnormality being stopped, the duct to which the suction device thus stopped is connected being maintained at negative pressure by other, normal suction devices connected to the duct. 6 . A fiber bundle collecting device according to claim 5, wherein each suction device includes a suction fan and a motor for rotationally driving the suction fan, the abnormality detecting means including a sensor for detecting a rotating speed of each motor. 7. A spinning machine equipped with a fiber bundle collecting device according to any one of claims 1 to 6. 8. A spinning machine equipped with a fiber bundle collecting device according to any one of claims 1 to 4, comprising abnormality detecting means for detecting any abnormality in the plurality of suction devices, when the abnormality detecting means detects abnormality in any one of the suction devices, the spinning by all the spindle units being stopped. 9. A spinning machine according to claim 8, wherein each suction device includes a suction fan and a motor for rotationally driving the suction fan, the abnormality detecting means including a sensor for detecting a rotating speed of each motor. 10, A fiber bundle collecting device substantially as herein described with reference to the accompanying drawings. 11. A spinning machine substantially as herein described with reference to the accompanying drawings.

Documents:

715-che-2003-abstract.pdf

715-che-2003-claims duplicate.pdf

715-che-2003-claims original.pdf

715-che-2003-correspondnece-others.pdf

715-che-2003-correspondnece-po.pdf

715-che-2003-description(complete) duplicate.pdf

715-che-2003-description(complete) original.pdf

715-che-2003-drawings.pdf

715-che-2003-form 1.pdf

715-che-2003-form 26.pdf

715-che-2003-form 3.pdf

715-che-2003-form 5.pdf

715-che-2003-other documents.pdf