Abstract:
The present invention provides a method for manufacturing a fabric and an apparatus for manufacturing a fabric that enable weaving of weak fibers including monofilaments of noble metal such as 24-carat gold. The present invention provides a method for manufacturing a fabric using a power loom driven by driving means, comprising the steps of: (a) separating a warp into an upper part and a lower part to form a shed by means of rotation of said driving means; (b) accelerating a weft thread toward said shed by means of rotation of said driving means; (c) passing said weft thread through said shed by means of rotation of said driving means; (d) decelerating said weft thread passed through said shed by means of rotation of said driving means; (e) returning said warp to close said shed by means of rotation of said driving means; and (f) beating said weft thread inserted into said warp in said step (c) to draw up said weft thread into near side by means of rotation of said driving means; rotational speed of said driving means during said steps (b) and (d) being lower than rotational speed of said driving means during said step (c).

Description:
FIELD OF THE INVENTION 
   The present invention relates to method of manufacturing a fabric and an apparatus for manufacturing a fabric and more particularly to a method of manufacturing a fabric and an apparatus for manufacturing a fabric that can weave a fabric from weak filament, such as monofilaments of noble metal. 
   BACKGROUND ART 
   Conventionally, it has been difficult to weave a fabric from a very weak fiber, especially monofilaments of fine gold, an extrafine fiber, or an extra-weak fiber. Fabric woven from monofilaments of noble metal, especially fabric woven from monofilaments of fine gold, can be expected to semi-permanently retain its original luster and beauty and demand a high price as a material for ornaments. Attempts have therefore been made to produce such fabric from many years ago. Non-patent document 1 describes the structure of an apparatus for manufacturing a fabric and a method for manufacturing a fabric. Further, the Patent Document 1 discloses a method for weaving a fabric from monofilaments of noble metal and an apparatus for weaving the same. 
   [Non-Patent Document 1] “Machine Weaving” (the Ministry of Education, Science and Culture, Jikkyo Shuppan, Feb. 25, 1959, p.p 14–193) 
   [Patent Document 1] Japanese Patent Laid-Open No. 2002-4150 
   However, by using the method disclosed by the Patent Document 1, it is not possible to weave a fabric from an arbitrary weak fiber, since the method sets a limit on the tensile strength of the fiber to be woven. In this specification, the term “noble metal” will be used to generally refer to metals such as gold, silver, platinum, iridium, and various alloys containing them in combination. 
   Accordingly, it is an object of the present invention to provide method for manufacturing a fabric and an apparatus for manufacturing a fabric that enable weaving of weak fibers including monofilaments of noble metals such as 24-carat gold. 
   SUMMARY OF THE INVENTION 
   The present invention provides a method for manufacturing a fabric using a power loom driven by driving means, comprising the steps of: (a) separating a warp into an upper part and a lower part to form a shed by means of rotation of said driving means; (b) accelerating a weft thread toward said shed by means of rotation of said driving means; (c) passing said weft thread through said shed by means of rotation of said driving means; (d) decelerating said weft thread passed through said shed by means of rotation of said driving means; (e) returning said warp to close said shed by means of rotation of said driving means; and (f) beating said weft thread inserted into said warp in said step (c) to draw up said weft thread into near side by means of rotation of said driving means; a rotational speed of said driving means during said steps (b) and (d) being lower than a rotational speed of said driving means during said step (c). 
   In the present invention as set forth above, the following motions are generated at predetermined timing by means of the power of the driving means: (a) a shedding motion for separating the warp into an upper part and a lower part to form a shed; (b) an initial picking motion for accelerating the weft thread toward the shed; (c) a picking motion for passing the weft thread through the shed; (d) a terminal picking motion for decelerating the weft thread passed through the shed; (e) a closing motion for closing the shed; and (f) a beating motion for beating the weft thread inserted into the warp to draw up the weft thread into near side. The rotational speed of the driving means is reduced during the initial picking motion and the terminal picking motion. 
   In this arrangement of the present invention, shock force liable to break the weft thread can be prevented during the initial picking motion for accelerating the weft thread and the terminal picking motion for decelerating the weft thread. In addition, problems such as loosening of the weft are prevented and fabric productivity is enhanced by the apparatus according to the present invention. This is because during the picking motion the rotational speed of the driving means is higher than the rotational speed during the initial picking motion and the terminal picking motion. 
   Preferably, the rotational speed of the driving means during the initial picking motion and the terminal picking motion is ¼ or less the rotational speed of said driving means during the picking motion. 
   In this arrangement of the present invention, the fabric productivity is enhanced while breaking of the weft thread is prevented. 
   Preferably, the driving means is an electric motor and the rotational speed of the electric motor is varied by an inverter. 
   In this arrangement of the present invention, the rotational speed is smoothly varied with high energy efficiency. 
   Preferably the driving means is an electric motor and the rotational speed of the electric motor is varied by switching a switch in response to the beating motion by which a reed is moved. 
   In this arrangement of the present invention, a suitable switch is changed by means of reciprocating motion of the reed performing beating motion and the rotating speed of the driving means is varied on the basis of the position of the switch. 
   By this arrangement of the present invention, the time for operating the switch can be detected with simple mechanism. 
   The present invention also provides an apparatus for manufacturing a fabric comprising: driving means for generating rotational force; healds for transferring a warp upward or downward to form a shed at predetermined timing in response to a rotation of said driving means; a shuttle for holding a weft thread and transferred into said shed so as to cross said warp at predetermined timing in response to a rotation of said driving means; a shuttle box for slidably supporting said shuttle and picking said shuttle into said shed at predetermined timing in response to a rotation of said driving means; a reed attached to said shuttle box for beating said weft thread inserted into said warp by picking said shuttle, said reed being reciprocated at predetermined timing by means of a rotation of said driving means to draw up said weft thread into a near side; and means for varying rotational speed of said driving means at predetermined timing. 
   In the present invention as set forth above, the motion of the healds forming the shed, the motion of picking the shuttle into the shed and the motion of drawing the reed up the weft thread into the near side are performed by means of the rotation of the driving means and the rotational speed of the driving means is varied at predetermined timing. 
   In this arrangement of the present invention, the rotational speed of the driving means is reduced during motions that tend to apply shock force to the weft thread, whereby the shock force applied to the weft thread is reduced and breaking of the weft thread is prevented. 
   Preferably said means for varying the rotational speed decreases rotational speed of the driving means at least when the shuttle is accelerated toward the shed and when the shuttle is decelerated after passing through the shed. 
   Further, in the present invention, the driving means is preferably an electric motor and the means for varying rotational speed is preferably an inverter connected to the electric motor. 
   Further, in the present invention, the apparatus preferably further comprises a limit switch that is switched by means of reciprocating motion of the shuttle box and the means for varying rotational speed varies the rotational speed of the driving means on the basis of the position of the limit switch. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will be best understood in conjunction with the accompanying drawings throughout which like reference numerals generally denote equivalent or similar elements: 
       FIG. 1  is a perspective view of an apparatus for manufacturing a fabric according to a preferred embodiment of the present invention. 
       FIG. 2  is a schematic view of the apparatus for manufacturing a fabric according to the preferred embodiment of the present invention. 
       FIG. 3  is a perspective view illustrating a mechanism for changing the rotational speed of a motor of the apparatus according to the preferred embodiment of the present invention. 
       FIG. 4  is a plan view illustrating a shuttle and a shuttle box of the apparatus according to the preferred embodiment of the present invention. 
       FIG. 5  is a front elevation view illustrating a shuttle and a shuttle box of the apparatus according to the preferred embodiment of the present invention. 
       FIG. 6A  is a graph showing the relationship between contacting position of a flexible lever and rotational speed. 
       FIG. 6B  is a graph showing the relationship between rotational angle of a crankshaft and rotational speed. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Preferred embodiments of the present invention will now be described with reference to the accompanying drawings.  FIG. 1  is a perspective view of an apparatus for manufacturing a fabric according to a preferred embodiment of the present invention illustrating primary structures of the apparatus.  FIG. 2  is a schematic view illustrating relationships among parts of the apparatus. As illustrated in  FIGS. 1 and 2 , the apparatus  1  according to this embodiment of the present invention comprises driving means, i.e., a motor  2 , for generating power, a pulley  4  driven by the motor  2  through a belt, a crankshaft  6  to which the pulley  4  is secured, and a connecting rod  8  connected to the crankshaft  6 . 
   The apparatus  1  according to the embodiment of the present invention further comprises a shuttle box  10  reciprocated by the connecting rod  8 , a pair of rails  12  guiding horizontal motion of the shuttle box  10 , a shuttle  14  retaining the weft thread and slidably supported in the shuttle box  10 , and a reed  16  attached to the shuttle box  10 . An extension bar  18  having a shoulder portion is attached to the shuttle box  10 . The apparatus  1  further comprises a flexible lever  20  positioned so that the extension bar  18  is in contact with the flexible lever  20 , a limit switch  22  attached to the flexible lever  20 , means for varying rotational speed, i.e., an inverter  24 , that varies the rotational speed of the motor  2  in response to switching of the limit switch  22 , and a power supply  26  supplying power to the inverter  24 . 
   The motor  2  is adapted to drive the pulley  4  through the belt. Since the diameter of the pulley  4  is larger than that of the pulley attached to the drive shaft of the motor  2 , the rotation of the motor  2  transmitted to the pulley  4  is decelerated. The crankshaft  6  is driven by the pulley  4  and reciprocates the shuttle box  10  along the pair of rails  12  through the connecting rod  8 . The reed  16  attached to the shuttle box  10  is a comb-like plate having many slots parallelly extending in the vertical direction and reciprocates together with the shuttle box  10  to beat the weft thread. 
   The configuration of the extension bar  18  with shoulder portion and the limit switch  22  will now be explained with reference to  FIG. 3 . The extension bar  18  attached to the shuttle box  10  is longitudinally reciprocated with the shuttle box. As shown in  FIG. 3 , the flexible lever  20  attached to the limit switch  22  is arranged to be in constant contact with the extension bar  18 . The flexible lever  20  is bent by the shoulder portion of the extension bar  18  when the extension bar  18  is moved ahead. The shoulder portion of the extension bar  18  is rounded so that the flexible lever  20  is smoothly bent. The limit switch  22  is switched when the flexible lever  20  is bent. The inverter  24  is connected to the limit switch  22 , and when the limit switch  22  is switched, the inverter  24  changes the speed of the motor  2 . 
   The apparatus  1  according to this embodiment of the present invention further comprises a yarn beam  28  on which the warp A is wound, a back beam  30  for guiding the warp A from the yarn beam  28 , lease rods  32  inserted into the warp A, two healds  34   a  and  34   b  that pull the warp A up or down at predetermined timing in order to form a shed C, a breast beam  36  guiding the warp A passing through the heald  34   a  and  34   b  and the reed  16 , and a take-up roller  38  for taking up the fabric produced. 
   The apparatus  1  according to this embodiment of the present invention further comprises two treadles  40   a  and  40   b  that pull down the healds  34   a  and  34   b,  respectively, a tappet  42  downwardly pushing against each treadle  40  at predetermined timing, a bottom shaft  44  to which the tappet  42  is attached, a large gear  46  attached to the bottom shaft  44 , and a small gear  48  attached to the crank shaft  6  and engaged with the large gear  46 . 
   The threads of warp A pass through either the heald  34   a  or the heald  34   b.  The bottom ends of the healds  34   a  and  34   b  are connected to end portions of the treadles  40   a  and  40   b,  respectively. The other end portions of the treadles  40   a  and  40   b  are pivotably supported. As the gear ratio of the small gear  48  attached to the crank shaft  6  to the large gear  46  attached to the bottom shaft  44  is 1:2, if the crank shaft  6  rotates 2 revolutions, the bottom shaft  44  will rotate 1 revolution. The tappet  42  attached to the bottom shaft  44  includes two generally circular members  42   a  and  42   b,  which are secured to the bottom shaft  44  at an eccentric position of the circular members  42   a  and  42   b.  The two generally circular members  42   a  and  42   b  are overlapped so that the point on the circular member  42   a  that is most distant from the bottom shaft  44  lies on the side opposite to the point on the circular member  42   b  that is most distant from the bottom shaft  44 . The bottom shaft  44  is arranged so that the circular member  42   a  downwardly pushes the treadle  40   a  to pull down the heald  34   a  and the circular member  42   b  downwardly pushes the treadle  40   b  to pull down the heald  34   b  during one revolution of the bottom shaft  44 . 
   The structure of the shuttle  14  and the shuttle box  10  will now be explained with reference to  FIGS. 4 and 5 .  FIG. 4  is a plan view of the shuttle  14  and the shuttle box  10 , and  FIG. 5  is a front view of the same. The shuttle box  10  is shown partly cut off to simplify the figures. As shown in  FIGS. 4 and 5 , the shuttle box  10  comprises two tangs  54  inserted into apertures formed on a bottom surface of the shuttle  14  to drive the shuttle  14  in the horizontal direction across the warp A, a sliding plate  50  that retains the tangs  54  allowing movement in the vertical direction and drives the tangs  54  in the horizontal direction, a guide rail  56  located below the sliding plate  50  and guiding the vertical motion of the tangs  54 , and guide members  52  guiding the horizontal motion of the shuttle  14 . 
   The shuttle  14  comprises a bobbin  58  that is rotatably supported and on which the weft thread is wound, two coil springs  62  positioned in passages  60  formed through the body of the shuttle  14 , one end of the coil springs  62  being attached to the body of the shuttle, rings  64  attached to the ends of the coil springs  62 , an arcuate member  66  in the form of an arch and secured to the front of the body of the shuttle  14 , a semicircular member  68  attached to the top portion of the arcuate member  66 , a ring  70  through which the semicircular member  68  is inserted, and two apertures  72  formed on a bottom surface of the shuttle  14  and receiving the tangs  54 . An aperture  66   a  is formed on the top portion of the arcuate member  66  for passage of the weft thread. 
   The rotation of the crank shaft  6  causes the shuttle box  10  to be reciprocated in longitudinal direction through the connecting rod  8 . The sliding plate  50  supported by the shuttle box  10  is laterally reciprocated above the guide rail  56  to synchronize with the reciprocating motion of the shuttle box  10 . The elevation of the guide rail  56  is high on both side of the warp A and is low below the warp A. 
   When the sliding plate  50  is reciprocated, the tangs  54  protruding from the sliding plate  50  are laterally reciprocated with the sliding plate  50 . As the tangs  54  are slidable in vertical direction relative to the sliding plate  50 , the tangs  54  are moved in the vertical direction along the contour of the guide rail  56 . Therefore, the tangs  54  are retracted into the sliding plate  50  when they are located under the warp A and are projected from the sliding plate  50  when they are both located on the side of the warp A. As the shuttle  14  in the shuttle box  10  has the apertures  72  for accepting the tangs  54 , the shuttle  14  is driven in the lateral direction across the warp A. 
   Next, the operation of the apparatus for manufacturing a fabric according to this preferred embodiment of the present invention will be explained. First, the threads of the warp A to be woven by winding them in parallel around the yarn beam  28 . The yarn beam  28  is set at a predetermined position of the apparatus  1 , and the warp A is passed through the back beam  30 , lease rods  32 , and healds  34   a  or  34   b.  In this embodiment, the threads of the warp A are alternately inserted into the healds  34   a  and  34   b.  The warp A passing through the healds  34   a  or  34   b  is passed through the reed  16  and breast beam  36  and wound around the take-up roller  38 . 
   The thread of the weft B is prepared. The thread of the weft B is wound around the bobbin  58  and the bobbin  58  is set in the shuttle  14 . The thread of the weft B is drawn from the bobbin and passed through the ring  70  attached to the semicircular member  68  of the shuttle  14 . The thread of the weft B passed through the ring  70  is passed through the ring  64  attached to the distal end of the coil spring  64 , and then passed through the another ring  64  attached to the distal end of the another coil spring  64 , and lastly passed through the aperture  66   a  formed on the top of the arcuate member  66 . After preparation of the thread of the weft B, the shuttle  14  is positioned in the shuttle box  10 . It is necessary to position the shuttle  14  so that the tangs  54  projecting from the sliding plate  50  of the shuttle box  10  are inserted into the apertures  72  formed on the bottom of the shuttle  14 . 
   The shedding motion, one of the primary motions of the apparatus  1 , will be explained. The rotation of the motor  2  is transmitted through the belt to the pulley  4  and the rotation of the pulley  4  is transmitted to the small gear  48  secured to the crankshaft  6 . The rotation of the small gear  48  is transmitted to the large gear  46  engaged with the small gear  48 , and the bottom shaft  44  secured to the large gear  46  is rotated. The rotation of the bottom shaft  44  rotates the tappet  42  attached thereto. As shown in  FIG. 2 , in a position where the circular member  42   a  of the tappet  42  is lowered, the treadle  40   a  is downwardly pushed and the heald  34   a  connected to the treadle  40   a  is lowered. On the other hand, in this position, the circular member  42   b  of the tappet  42  is raised and the treadle  40   b  is not pushed, thus the heald  34   b  connected to the treadle  40   b  is raised. As a result, the part of the warp A passed through the heald  34   a  is lowered and the part of the warp A passed through the heald  34   b  is raised, thus a shed C is formed between the lowered part of the warp and the raised part of the warp. 
   When the bottom shaft  44  rotates about ninety degrees and the circular members  42   a  and  42   b  of the tappet  42  are located on the same level, the shed C is closed because the treadles  40   a  and  40   b  are not lowered and healds  34   a  and  34   b  are on the same level. When the bottom shaft  44  further rotates about ninety degrees and the circular member  42   b  of the tappet  42  is at a lower position and the circular member  42   a  is at an upper position, the heald  34   b  is lowered and the heald  34   a  is raised, thereby forming the shed C. Since the gear ratio of the small gear  48  and the large gear  46  is 1:2, when the crankshaft  6  rotates two revolutions, the bottom shaft  44  rotates in one revolution. Further, while the bottom shaft  44  rotates one revolution, the shed C is formed twice, Thus the shed C is formed once during each revolution of the crankshaft  6 . 
   Next, a picking motion, one of the primary motions of the apparatus  1  for manufacturing a fabric according to the preferred embodiment of the present invention, will be explained. The motor  2  drives the crankshaft  6  and the connecting rod  8  connected to the crankshaft  6  reciprocates the shuttle box  10  in the longitudinal direction. This reciprocating motion causes the sliding plate  50  to reciprocate in the lateral direction by means of a sliding plate drive mechanism (not shown). The shuttle  14  is laterally reciprocated together with the sliding plate  50 , since the two apertures  72  formed on the bottom surface of the shuttle  14  receive the two tangs  54 . In a step for initiating the picking motion, the shuttle  14  slowly starts to accelerate from the position most distant form the warp A toward the warp A. The velocity of the shuttle  14  is fastest in the step of picking motion in which the shuttle  14  passes through the shed C. Then, in a step for terminating the picking motion, the shuttle  14  starts to decelerate from the position where the shuttle  14  has passed through the shed C and stops at the point most distant from the warp A. Again, the shuttle  14  starts to accelerate toward the warp A in the reverse direction in another step for initiating a picking motion. By repeating these motions, the shuttle  14  successively passes the thread of the weft B between the threads of the warp A. 
   As shown in  FIG. 5 , when the shuttle  14  moves rightward and approaches the warp A, causing the tangs  54  inserted into the apertures  72  of the shuttle  14  to approach the position where the elevation of the guide rail  56  is low, the tang  54  on the right side goes down and comes out of the aperture  72 . Thus, when the shuttle  14  approaches the warp A, the tang  54  on the right side first starts to go down along the guide rail  56  and the tang  54  on the right side is not upwardly projected from the sliding plate  50  below the warp A. Next, when the shuttle  14  is moved farther and the tang  54  on the left side approaches the warp A, the tang  54  on the left side also starts to go down and to come out of the aperture  72 . At the same time, the tang  54  on the right side starts to go upwardly along the guide rail  56  and is inserted into the aperture  72  of the shuttle  14 . Then, when the shuttle  14  is moved farther and the tang  54  on the left side also passes through the warp A, the tang  54  on the left side also starts to go upwardly and is inserted into the aperture  72 . 
   Next, a beating motion, one of the primary motions of the apparatus  1  according to the preferred embodiment of the present invention, will be explained. The motor  2  drives the crankshaft  6  and the connecting rod  8  connected to the crankshaft  6  reciprocates the shuttle box  10  in longitudinal direction. When the shuttle box  10  is reciprocated and the reed  16  attached to the shuttle box  10  is also reciprocated, the reed  16  draws up the thread of weft B passed through the shed C into the near side. 
   Referring  FIGS. 3 and 6 , the timing of the primary motions and the rotating speed of the motor  2  of the apparatus  1  according to this preferred embodiment of the present invention will be explained.  FIG. 6A  shows the relationship between the contacting point on the extension bar with the flexible lever  20  and the rotating speed of the crankshaft  6 .  FIG. 6B  shows a relationship between the rotating angle and the rotating speed of the crankshaft  6 . The three primary motions explained above, i.e., the shedding motion, the picking motion and the beating motion, are generated by motive power of the motor  2  and are synchronized with the rotation of the motor  2 . At a moment of the beating i.e. the moment when the shuttle box  10  is most advanced toward the near side, the shuttle box  10  is stopped and the flexible lever  20  attached to the limit switch  22  is downwardly bent by abutting on the point P 1  of the extension bar  18  attached to the shuttle box  10 . This moment corresponds to the point P 1  on the left end of the graph of  FIG. 6A  and corresponds to the point of zero degree in  FIG. 6B  (the direction of zero degree in  FIG. 6B  does not correspond to the crank angle of the crankshaft  6 ). While the flexible lever  20  is downwardly bent, the limit switch  22  is on and the inverter  24  is operated to reduce the rotating speed of the motor  2 . 
   After the beating motion, when the shuttle box  10  starts to move backward, the circular member  42   a  or  42   b  of the tappet  42  starts to push the treadle  40  down and the shed C is opened. Further, the shuttle  14  in the shuttle box  10  starts to accelerate toward the warp A. This motion corresponds to the left end section between the points P 1  and P 2  in  FIG. 6A  and corresponds to the section between the angles 0 to 90 in  FIG. 6B . When the shuttle box  10  further moves backward and the flexible lever  20  is abutted on the point P 2  of the extension bar  18 , the shed C is completely opened and the shuttle  14  approaches the shed C. 
   When the shuttle box  10  further moves backward and the flexible lever  20  passes beyond the point P 2 , the flexible lever  20  is no longer bent and the limit switch  22  is turned off. When the limit switch  22  is off, the operation of the inverter  24  is stopped to increase the speed of the motor  2 . When the flexible lever  20  passes beyond the point P 2 , the shuttle  14  is running within the shed C and the shed C is maintained at full-open position. This motion corresponds to the section between the point P 2  on left side and the point P 3  in  FIG. 6A  and corresponds to the section between the angles 90 and 180 degrees in  FIG. 6B . 
   When the shuttle box  10  moves to the position where the flexible lever  20  is in contact with the point P 3  of the extension bar  18 , the moving direction of the shuttle box  10  is changed and the shuttle box  10  starts to move foreward. While the shuttle box  10  is moving between the first position in which the flexible lever  20  is in contact with the point P 3  and the second position in which the flexible lever  20  is in contact with the point P 2 , the limit switch  22  is off and the rotating speed of the motor  2  is high. In this period, the shuttle  14  is still located within the shed C and the shed C is maintained at full-open position. This motion corresponds to the section between the point P 3  and the point P 2  on right side of  FIG. 6A  and corresponds to the section between the angles 180 and 270 degrees in  FIG. 6B . 
   When the shuttle box  10  further moves in foreward and the flexible lever  20  comes in contact with the point P 2  of the extension bar  18 , the flexible lever  20  is bent again and the limit switch  22  is turned on, whereby inverter  24  is operated to reduce the rotating speed of the motor  2 . At this moment, the shuttle  14  has been passed through the shed C and starts to decelerate and the shed C starts to close. This motion corresponds to the section between the point P 2  on right side and the point P 3  on the right side in  FIG. 6A  and corresponds to the section between the angle 270 and 0 in  FIG. 6B . When the shuttle box  10  further moves in foreward and the flexible lever  20  comes in contact with the point P 1  of the extension bar  18 , the reed  16  attached to the shuttle box  10  draws up the thread of weft B into the near side by the beating motion. At this moment, the shuttle  14  is stopped and the shed C is closed. By repeating these motions, the threads of the weft B are passed across the warp A one after another. 
   In this embodiment, during the steps for initiating the picking motion and for terminating the picking motion in which the limit switch  22  is on, the motor  2  is driven so as to rotate the crankshaft  6  at 20 rpm. During the step of picking motion, in which the limit switch is off, the motor  2  is driven so as to rotate the crankshaft  6  at 80 rpm. In this embodiment, transparent films of narrow width are utilized as the threads of the warp A, and a 24-carat gold monofilament having a diameter of 30 micrometer is utilized as the thread of the weft B. 
   The apparatus for manufacturing a fabric according to this preferred embodiment of the present invention can produce a fabric from very weak filament which has been impossible to produce using a conventional apparatus. This is possible because, during the step for initiating a picking motion in which the thread of the weft B is accelerated toward the shed C and the step for terminating the picking motion in which the thread of the weft B is decelerated, the crankshaft  6  is rotated at low speed and the force applied to the thread of weft B is very weak. Further, problems such as loosening of the weft B are prevented and the fabric productivity is enhanced by the apparatus according to this preferred embodiment of the present invention. This because, during the picking motion in which the shuttle  14  is passed through the shed C, the crankshaft  6  of the apparatus according to this preferred embodiment is rotated as fast as the crankshaft of a conventional apparatus. 
   Although a preferred embodiment according to the present invention has been explained, the preferred embodiment can be modified. In the embodiment set forth above, the present invention is applied to an apparatus for manufacturing a narrow width fabric utilizing a shuttle. However, the present invention can be applied to an arbitrary weaving apparatus such as an apparatus for manufacturing a broad width fabric, a shuttle-less weaving apparatus and a needle weaving apparatus. In the embodiment set forth above, 24-carat gold monofilament is used to produce a fabric, but any of various other very weak fibers can also be woven by the apparatus according to the present invention. Further, in the preferred embodiment set forth above, transparent films are utilized as the treads of the warp A and a 24-carat gold monofilament is utilized as the thread weft B. However, a very weak fiber such as a 24-carat gold monofilament can be also utilized for the warp. In the preferred embodiment set forth above, a plain weave fabric is produced, but various types of fabric can be woven by the apparatus according to the present invention by using more than two healds. 
   Further, in the preferred embodiment set forth above, the limit switch is switched by the extension bar having the shoulder portion that is reciprocated together with the shuttle box in order to vary a rotating speed of the motor. However, the extension bar can be replaced by a cam or tappet. That is, it is possible to attach a cam or tappet to the crankshaft or a shaft rotatingly synchronized with the crankshaft and use this cam or tappet to switch the limit switch at predetermined rotating angles.