US3704579A

US3704579A - Practical method and apparatus for driving an open-end spinning frame

Info

Publication number: US3704579A
Application number: US134726A
Authority: US
Inventors: Takuzo Tooka; Choji Nozaki; Kiichi Kono
Original assignee: Toyota Central R&D Labs Inc; Toyoda Automatic Loom Works Ltd
Current assignee: Toyota Industries Corp; Toyota Central R&D Labs Inc
Priority date: 1970-04-18
Filing date: 1971-04-16
Publication date: 1972-12-05
Anticipated expiration: 1989-12-05
Also published as: CH539692A; FR2086176A1; JPS5034649B1; DE2118775C2; GB1343934A; FR2086176B1; DE2118775A1

Abstract

Method and apparatus capable of controlling the driving speed of the open-end spinning frame utilizing a plurality of spinning units by applying at least two variable frequency electric sources. A first electric source is used for driving all spinning units for carrying out the normal spinning operation, while a second electric source is used for driving a spinning unit of yarn breakages used for carrying out the yarn piecing operation. The latter source is mounted on a carriage capable of being displaced along the spinning frame and can be stopped at a desired working position correctly.

Description

United States Patent [151 3,704,579

Tooka et al. 1451 Dec. 5, 1972 [541 PRACTICAL METHOD AND [56] References Cited APPARATUS FOR DRIVING AN OPEN- END SPINNING FRAME UNITED STATES PATENTS 72 Inventors; Takuzo Tooka, Aichi gun; Choji 3,35%,631 ll/l967 Elias et al ..57/58.95 i; Kiichi Kano, both f 3,461,936 8/1969 Boucek et al.. ..57/58.89 Nagoya, n f Japan 3,541,774 11/1970 Sterba et al ..57/58.89 x

[731 Assignees: Kabushiki Kaisha Toyoda Jidoshok- P E H S h d ki Seisakusho, Aichi-ken; Kabushiki gg' f g j a' 'igf 23? c we er Kaisha Toyota Chuo Kenkyusho, Nagoya-shi, Japan 57] ABSTRACT [22] Filed: April 1971 Method and apparatus capable of controlling the driv- [21] Appl. No.: 134,726 ing speed of the open-end spinning frame utilizing a plurality of spinning units by applying at least two variable frequency electric sources. A first electric Forelgn Apphcatmn Pnonty Data source is used for driving all spinning units for carry- April 18, 1970 Japan ..45/33166 ing out the normal spinning operation, while a second electric source is used for driving a spinning unit of R, yam breakages used for carrying out the yarn piecing 57/100 57/156 operation. The latter source is mounted on a carriage Cl. ..D0lh of being displaced along spinning frame [58] Field of Search 57/34, 52, 58.89, and can be Stopped at a desired working position 57/58.9l, 58.93, 58.95, 93,100,156; rectly 13 Claims, 7 Drawing Figures PATENTED 5 I97? 3. 704,579

SHEET 3 UF 5 F /'g. 5A

58 ELEAcgRlc INPUT RECTIFIER COMSER'OR 'NVERTER OUTPUT SOURCE TRANS I [I L55 36 37 i 4| r 42 I CONTROL 43 CIRCUIT r "4'5 r fir STABILIZER 1") g 1 47 REFEREN L POTENTI PRACTICAL METHOD AND APPARATUS FOR- DRIVING AN OPEN-END SPINNING FRAME BRIEF SUMMARY OF THE INVENTION trifugal rotary spinning cavity into which liberated l0 fibers are continuously introduced to spin them into a yarn which is continuously delivered from the cavity, and selectively controlling the driving speed of one spinning unit for carrying out the yarn piecing operation.

It is well-known that the most practical open-end spinning method comprises liberating a bundle of fibers supplied from a supply mechanism into individual liberated fibers while passing through a liberating mechanism; introducing the liberated fibers into a centrifugal rotary spinning cavity of a rotor which is considered as a twisting mechanism so that introduced fibers are collected upon an inside peripheral wall of the cavity; continuously taking off the collected fibers from the inside peripheral wall of the cavity in a rebundled condition while providing twist to the rebundled fibers by a taking-off mechanism; and introducing the twisted rebundled fibers outside of the rotor; then winding the twisted rebundled fibers by a winding mechanism so that a yarn package such as a cheese is produced.

By utilizing the above-mentioned open-end spinning method, the productivity of yarn in the spinning room can be remarkably increased so that the maximum efficiency of the spinning factory can be attained. However, it is required to further increase the productivity of the-spinning frame together with the improvement of yarn quality.

Generally, rotatable members of the open-end spinning frame are mainly driven by means of the belt driving system, particularly, the spinning rotor is normally driven by the above-mentioned manner. Therefore, in the case of applying the belt driving system, if the rotating speed of the spinning rotor is to be considerably increased, it is inevitable that the power consumption for driving the open-end spinning frame is so increased and the driving is transmitted in an unstable condition, and further noises created by the driving mechanism and vibration of rotatable members become large. Further, the yarn piecing operation at the time of yarn breakage becomes more difficult in accordance with speeding up the spinning operation, because the timing of the yarn piecing operation is fairly difficult to negotiate. Therefore, the rotation speed of all rotors of the spinning frame may have to be temporarily lowered to carry out the above-mentioned yarn piecing operation and to solve the above-mentioned drawback. However, if the rotation speed of all spinning rotors is lowered, the productivity of the spinning frame is consequently reduced.

The principal object of the present invention is to provide the most preferable method and apparatus for driving the open-end spinning frame utilizing the above-mentioned spinning rotor, wherein each rotor is directly driven by a driving motor connected thereto instead of applying the well-known belt driving mechanism, and each driving motor can be connected to a pair of variable frequency electric sources alternatively.

Another object of the present invention is to provide a practical method and apparatus for driving the openend spinning frame utilizing at least a pair of variable frequency electric sources, that is, a first variable frequency electric source mainly used for driving all spinning units of the frame at a predetermined higher speed, and a second variable frequency electric source which is carried by a carriage and is used for driving a spinning unit that has a yarn break at a predetermined lower speed during the yarn piecing operation.

According to the present invention, each rotor is directly driven by a motor which is capable of being connected alternatively to a pair of variable frequency electric sources. One of the variable speed electric sources is stationarily mounted on the spinning frame, while another variable speed electric source is mounted on a carrier which can be displaced along the lengthwise direction of the spinning frame. The stationary electric source is used for driving all spinning units at a predetermined very high speed, for example very high speed rotation of the spinning rotor more than 40,000 r.p.m. for carrying out the normal spinning operation, while another electric source is used for driving a spinning unit that has a yarn break at a predetermined low speed during the yarn piecing operation.

Therefore, the working efficiency of the open-end spinning frame can be remarkably increased, while the yarn piecing operation can be easily and perfectly carried out.

Other objects and features of the invention will more fully appear from the following description and the accompanying drawings and will be particularly pointed out in the claims.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a diagrammatic view of a spinning unit of an open-end spinning frame, showing an electrical connection for driving a unit, according to the present invention,

FIG. 2A is a somewhat schematic plan view of an open-end spinning frame, showing an electric circuit according to the present invention,

FIG. 2B is a partial diagram of the electric circuit shown in FIG. 2A,

FIGS. 3A and 3B are diagrams showing one example of electric circuit of a static variable frequency source utilized for the present invention,

FIG. 4 is a block diagram of a control system for maintaining the ratios of driving speeds of feed rollers and draw-off rollers to that of a spinning rotor, according to the present invention,

FIG. 5 is a modified embodiment for driving the open-end spinning frame, according to the present invention.

DETAILED DESCRIPTION In an apparatus for driving an open-end spinning frame according to the present invention, at least a spinning rotor, and a pair of feed rollers, a pair of drawoff rollers of each spinning unit are connected to respective individual variable speed motors. A take-up roller is driven through a gear box by a motor for driving the draw-off rollers. A spinning rotor of each spinning unit may be directly driven by an individual variable speed motor. The above-mentioned three motors for driving the spinning rotor, feed rollers and draw-off rollers are connected to variable frequency electric sources. Two types of variable frequency electric sources, that is, a generator which is driven by a variable speed electric motor and a static variable frequency electric source comprising elements such as a thyristor, are suitably utilized for the present invention.

For convenience of illustration of the present invention, firstly, a basic embodiment of the present invention is hereinafter illustrated.

Referring to FIG. 1, which shows a spinning unit comprising a spinning rotor 3 provided with a cavity forming a fiber collecting wall 4, a combing roller 2 which is a member for liberating a bundle of fibers into separated fibers and feeding the liberated fibers into the cavity so as to deposit the fibers upon the fiber collecting wall 4, a pair of feed rollers la, 1b for supplying a bundle of fibers, a pair of draw-off rollers 5 and 6 for delivering a yarn 7 from the spinning rotor 3 and a take-up roller 8 which is a winding mechanism, for producing a package 9, the spinning rotor 3 and the draw-off roller 5 are driven directly by the respective individual variable speed motors 11 and 12. The feed roller 1a driven by a variable speed motor by way of a set ofa worm and worm wheel mechanism 14 and the take-up roller 8 is driven by the motor 12 by way of a sprocket wheel 16a secured upon a connecting shaft between the roller 5 and the motor 12 and another sprocket wheel 16b secured upon a shaft of the roller 8 and a chain 160 connecting both

sprocket wheels

16a and 16b. The combing roller 2 is driven by a common driving belt 17 in a similar manner to the conventional driving mechanism of the open-end spinning frame, because it is not required to drive the combing roller 2 in a synchronized condition with a constant driving ratio to the spinning rotor 3. Referring to FIGS. 2A and 28, a static variable frequency electric source (E (hereinafter referred to as a first electric source), comprises a variable speed motor 18, and a pair of

generators

20 and 21 which are driven by the motor 18 at a predetermined reduced ratio by way of a reduction gear box 19, and a generator 22 which is driven by the motor 18. The

variable speed motors

10, 11 and 12 of each spinning unit (S) are connected to the respective conductors b, 24b, 23b which are connected to the

respective generators

21, 22 and 20 during the normal spinning operation.

The motor 18 is driven at a predetermined very high speed during the normal spinning operation, and therefore, the generator 22 generates an output of very high frequency while the

generators

20 and 21 generate outputs of high frequency in the relative condition with that of the generator 22 so that the spinning rotor 3 is driven at very high speed while the feed roller 1a and the draw-off roller 5 are driven at their relative high speed. The rollers lb and 6 are rotatably driven by the rollers la and 5, respectively. As mentioned above, the rotor 3 of each spinning unit (S) can be easily driven at very high speed, for example, at around 60,000 rpm. which is almost double that of the conventional belt driving system. Consequently, the centrifugal force of fibers effected upon the collecting surface of the spinning rotor 3 is remarkably enhanced so that fibers tend to be taken-off from the collecting surface in a more straightened condition and when these fibers are taken-off from the collecting surface so as to form a rebundled fiber-strand with twists, that is, a yarn 7, the quality of yarn can be improved considerably. As the production rate per unit time is determined by the takeup speed of yarn 7 from the spinning rotor 3 and the required number of twists to be imparted to the yarn 7 taken-up from the spinning rotor 3 is defined by the number of revolutions of the rotor 3 per a unit time and the take-up speed of yarn 7 from the rotor 3, the possibility of increasing the rotation speed of the rotor 3 means the raising of the productivity of the open-end spinning frame. In other words, the productivity of the open-end spinning frame can be remarkably enhanced by increasing the rotational speed of the feed rollers 10, lb, draw-off rollers 5, 6, take-up roller 8, together with considerable speeding up of the spinning rotors rotat1on.

When the spinning units (S) of the open-end spinning frame are initially started to drive simultaneously, the first electric source (E is applied so as to I drive the motors 10, l1 and 12 of each spinning unit (S). However, as it is required to piece an end of the prepared yarn with fibers introduced into each spinning rotor 3 just after supplying a bundle of fibers from the feed rollers la, 1b and the combing roller 2, the

generators

20, 21 are driven at a comparatively low speed by lowering the rotational speed of the variable speed motor 18 of the first electric source (E so as to generate output powers in their condition of lower frequencies. The generator 22 is also driven at a comparatively low speed. Therefore, the

motors

10, 11 and 12 of each spinning unit (S) are driven at a lower speed so that the above-mentioned piecing operation can be satisfactorily completed. After completion of the above-mentioned yarn piecing operation, the condition of the first electric source (E is returned to its normal driving condition so that the

motors

10, 11 and 12 are driven at their higher speeds which are maintained in a constant related condition. Consequently, the rotation speeds of the feed rollers la, draw-off rollers 5, take-up roller 8 and the spinning rotor 3 are accelerated while maintaining their comparative speed ratios.

As already described the driving apparatus according to the present invention is provided with another variable frequency electric source (E which is used for driving a spinning unit that has a yarn break at a predetermined low speed during the yarn piecing operation. (This electric source (E is hereinafter referred to as a second electric source.) The second electric source (E is carried by a carrier 31 which can be displaced along a pair of

guide rails

32a, 32b horizontally supported by the spinning frame A. The carrier 31 is provided with a grooved wheel 34a which is driven by a drive mechanism (not shown) mounted thereon, and a wheel 34b which rides on the guide rail 32b. The grooved wheel 34a also rides on the guide rail 32a as shown in FIG. 1. In this case, the carrier is automatically displaced to a working position for the yarn piecing operation in front of a spinning unit of yarn break when a detector such as a feeler (not shown) detects the yarn breakage. The second electric source (E 2) comprises a variable speed motor 26and a pair of

generators

28 and 29 which are driven by the motor 26 at a predetermined reduced ratio by way of a reduction gear box 27, and a generator 30 which is'driven by the motor 26. The motor 26 is driven by way of a conductor 33 which is connected to a main electric source (not shown). The variable speed motors l0, l1 and 12 of any one spinning unit (S) of yarn break can be temporarily connected to the

respective conductors

29a, 30a and 28a which are connected to the

respective generators

29, 30 and 28 during the yarn piecing operation, when the carrier 31 is stopped at a corresponding position before the spinning unit (S) that has the yarn break. The above-mentioned positioning of the carriage is performedby utilizing a braking means (not shown) which is actuated when the yarn break is detected by a detector such as a feeler (not shown), and a positioning means (not shown) which temporarily works to correct the stopped position of the carrier 31 in the similar manner to the above-mentioned yarn piecing apparatus.

Switches

23c, 24c and 250 are mounted on each spinning unit in such a way that these switches are connected to motors 12, and 11 by way of the

respective conductors

23a, 24a and 25a. The

switches

23c, 24c and 25c are normally closed to

respective terminals

23d, 24d and 25d which are connected to the

respective conductors

23b, 24b and 25b, during the normal spinning operation. However, when it is required to operate the yarn piecing operation, that is, the carriage 31 is displaced to the working position before a spinning unit that has the yarn break, these switches are turned to

terminals

28b, 29b and 30b which are directly connected to the

respective generators

28, 29 and 30 through the

respective conductors

28a, 29a and 30a, so that motors l2, l1 and 10 are driven by the second electric source (E As the

generators

28, 29 and 30 are driven at comparatively low speeds in comparison with the

generators

20, 21 and 22 of the first electric source (E the motors 10, II and 12 are driven at the'corresponding low speeds which are suitable for carrying out the yarn piecing operation. And after completion of the yarn piecing operation, the rotation speed of the motor 26 is increased so as to elevate the speeds of the motors l0, l1 and 12 on their normal condition for carrying out the spinning operation. And then the connection of these

switches

23c, 24c and 250 are again changed from the

terminals

28b, 29b and 30b to the

terminals

23d, 24d and 25d. Therefore, even though the spinning operation is carried out at very high speed by utilizing the first electric source (E there is no difficulty in carrying out the yarn piecing operation when the spinning yarn is broken.

The same effect as the above-mentioned driving by the second electric source (E can be attained for carrying out the yarn piecing operation at the time of commencing the spinning operation. That is, the driving speeds of motors I0, 11 and 12 of each spinning unit (S) are reduced by reduction of the driving speed of the variable motor 18 of the first electric source (E during the above-mentioned starting operation and then the driving speeds of these motors are gradually increased by speeding up the rotation of the motor 18 up to their normal operating condition.

Instead of utilizing the above-mentioned electric source, a static variable frequency electric source may be applied to the present invention. FIGS. 3A and 3B show one example of the static variable frequency electric source using semi-conductor elements such as a thyristor. Referring to FIG. 3A, an A.C. electric source 35 is connected via an input transformer 36 to a rectifier circuit 37, so that the output of the rectifier circuit 37 is applied to an inverter 39 via a converter 38. On the other hand, the output of the input transformer 36 is applied via a conductor 41 to a control circuit 40. The outputs of the control circuit 40 are respectively applied via

conductors

42 and 43 to the converter 38 and the inverter 39, and a variable frequency output is created on an output terminal 44. In the above-mentioned circuit, the rectifier circuit 37 rectifies the A.C. voltage of the A.C. electric source to a D.C. voltage, the converter 38 converts the output D.C. voltage of the rectifier circuit 37 to a variable D.C. voltage so that a voltage value of the converter circuit 38 is controlled by an output (via conductor 42) of the control circuit 40. The converter 38 is composed of a circuit utilizing the semi-conductor elements such as thyristors. The inverter 39 is also composed of the thyristor and is provided for inverting the output variable D.C. voltage of the converter 38 to an A.C. voltage having a desired frequency which is controlled by an output (via conductor 43) of the control circuit 40. One example of thecontrol circuit 40 is composed of, as shown in FIG. 38, a voltage stabilizer 45, an upper limit setting potentiometer 46, a lower limit setting potentiometer 48 and a variable value setting potentiometer 47. The conductor 41 is connected to the voltage stabilizer 45 and the upper and lower limit of low value setting potentiometers 46 and 48 are connected to the output of the voltage stabilizer 45. The upper limit of the voltage of the output 43 is determined by a setting value of the potentiometer 46 and the lower limit of the output 43 is determined by a setting value of the potentiometer 48. The variable value setting potentiometer 47 is two variable points of the potentiometers 46 and 48, and is controlled by a motor drive or manually. As a result of this, an output having a desired frequency is obtained on the output terminal 44.

In the above-mentioned embodiment shown in FIGS. 1 and 2 of the present invention, the

motors

10, 11 and 12 of each spinning unit (S) are driven with a predetermined driving speed ratio among them, by utilizing the reduction gear box. However, if these motors are driven separately by independent electric sources, it is required to maintain the driving speed ratio among them at a predetermined ratio to smoothly carry out the spinning operation. To satisfy the above-mentioned requirement, at particular control means is considered, as shown in FIG. 4. In this embodiment, the first variable frequency electric source (E comprises a variable speed motor 51 which is connected to a main electric source by way of a conductor 50, a generator 53 which is driven by the motor 51 by way of a variable speed power transmission means 52 such as P.I.V., and a conductor 5311 which applies an output of the generator 53 to a variable speed motor for driving the feed rollers of each spinning unit (S), and other similar variable frequency electric sources comprising the

respective conductors

60, 70,

variable speed motors

61, 71, a variable speed power transmission means 72, generators 62, 73 and conductors 62a, 73a, respectively. The conductor 62a applies the output of the generator 62 to a variable speed motor for driving the spinning rotor of each spinning unit (S), while the conductor 73a applies the output of the generator 73 to a variable speed motor for driving the draw-off rollers and take-up roller of each spinning unit (S). Therefore, it is necessary to control the driving speeds of these motors on a predetermined mutual relation. To attain the abovementioned requirement, the following control system is applied, that is, a variable speed motor 54, which has the same function as the motor for driving the feed rollers, is driven by the output of the generator 53 by way of a bypath conductor 53b, and a generator 55 is directly driven by the motor 54. In the variable frequency electric source for driving the spinning rotor, a variable speed motor 63, which has the same function as the motor for driving the spinning rotor, is connected to the generator 62 by way of a bypath conductor 62b, and a generator 64 is directly driven by the motor 63, while in the variable electric source for driving the draw-off rollers, a variable speed motor 74, which has the same function as the motor for driving the draw-off rollers, is connected to the generator 73 and a generator 75 is directly driven by the motor 74. The outputs of these

generators

55, 64 and 75 are amplified with a predetermined amplification degree by the

respective amplifiers

56, 65 and 76 so as to obtain equal magnitude of DC. output voltage. Therefore, the output voltages of these amplifiers are represented by 0 and 0 0 0 6 However, in the practical operation, there are certain differences between these DC. output voltages 0,, 0 and 0 In other words, there is a certain possibility of deviation from the desired driving speed of these motors. To avoid the above-mentioned deviation, a detector such as a differential amplifier 77 is applied to compare the output D.C. voltage of the amplifier 56 with that of the amplifier 65, and the output of the differential amplifier 77 is applied to a control motor 52a which regulates the output of the variable speed transmission means 52. In this control system, the generator 62 is directly driven by the variable speed motor 61. Only the driving speed of the feed roller is regulated while the driving speed of the spinning rotor is substantially maintained constant. The driving speed of the generator 73 is also controlled by the similar control system comprising the variable speed motor 74, generator 75 and the amplifier 76 and another differential amplifier 78 which compares the outputs of the

amplifiers

65 and 76 and actuates another control motor 72a by its output so that the variable speed transmission means 72 is regulated to drive the generator 73 at a predetermined speed. Therefore, the driving speed of the draw-off rollers is maintained in a predetermined condition. The abovementioned principle of the variable frequency electric source can be satisfactorily applied to a second variable frequency electric source (E In the above-mentioned embodiment, the

motors

10, 11 and 12 are single phase A.C. motors, and'conductors of common ground are represented by

reference numerals

15a, 15b and 15c, a two-way switch to connect the terminals of these conductors is represented by 15d. However, a three-phase A.C. motor may be used instead of the above-mentioned motors.

the carrier 31, a certain power is required to drive the carrier 31. To save the above-mentioned undesirable power consumption, it is preferable to displace only a section of

terminals

28b, 29b and 30b of the second electric-source (E in front of the spinning frame so as to be able to selectively connect them to the

respective terminals

23a, 24a and 25a of the spinning unit (S) wherein the yarn breakage is detected. In this case, the other elements of the second-electric source (E are disposed at a predetermined stationary position and these

terminals

28b, 29b and 30b are connected to

respective generators

28, 29 and 30 by way of a telescopic cable (not shown).

It is also practical that the carrier 31 is provided with a detector for detecting the yarn break and a yarn piecing device together with the second electric source (E and the carrier 31 always travels along the spinning frame. In this case, when the yarn breakage is detected by the detector, the carrier is stopped at the proper working position to carry out the yarn piecing operation and the terminals of the

conductors

23a, 24a and 25a are connected to the

respective terminals

28b, 29b and 30b of the second electric source (E).

In the modified embodiment shown in FIG. 5, feed rollers, draw-off rollers and a take-up roller of each spinning unit are driven by mechanical connections with the first or second electric sources (E or (E while the spinning rotor 3 of each spinning unit is driven by an electrical connection with the first or second electric sources (E or (E The feed roller la is driven by a driving shaft 94 by way of a worm and worm wheel mechanism 14. The driving shaft 94 is driven by a gear 1 19 or a gear 104 by way of an engaging action of a clutch means 96 which is slidably mounted on the shaft 94 by a so-called spline engagement. The gear 119 is rotatably mounted upon the shaft 94 so as to always engage with a gear 81 which is secured to a common driving shaft 92 at each position corresponding to each spinning unit (S). The common driving shaft 92 is driven by the first electric source (E The gear 104 is rotatably mounted upon the shaft 94 so as to be capable of engaging with a gear 102 which is driven by the second electric source (E when the yarn piecing operation is required. Therefore, by selectively changing the engagement of the clutch means 96 to the gear 119 or the gear 104 which is driven by the gear 102, the feed rollers 1a can be driven by the first electric source (E or the second electric source (E The driving mechanism of the draw-off roller 5 and the take-up roller 8 is similar to the abovementioned mechanism for driving the feed roller 1a, that is, the construction and function of gears 82, 103, 105, 120 and clutch means 97, are similar to the corresponding elements of the above-mentioned driving mechanism. A shaft drives the roller 5 while a shaft 93 is a common driving shaft for driving the respective gears 82 of each spinning unit (S). The rotor 3 is directly driven by a variable speed motor 11 which is connected to a common conductor 121, which is connected to the first electric source during the normal spinning operation, or is selectively connected to a conductor 108, which is connected to a generator 107 directly driven by a variable speed motor 106 mounted on a carrier 31, during the yarn piecing operation. The gear 102 is secured on a driving shaft 117 which is driven by a variable speed power transmission means 116 such as P.l.V. directly driven by the motor 106, while the gear 103 is secured on a driving shaft 118 rotatably mounted on the carrier 31 by way of a chain drive mechanism which is driven by the variable speed power transmission means 116 at a predetermined ratio of driving speeds between the shafts 117 and 118. The ratio of driving speeds between the shafts 92 and 93 is also fixed at the same predetermined ratio as the above-mentioned ratio. The motor 106 is driven at a comparatively low speed so as to drive the rotatable elements such as the feed rollers 1a, 1b, spinning rotor 3, draw-off rollers 5, 6 and take-up roller 8 at low speeds to carry out the yarn piecing operation.

In the above-mentioned second electric source (E the driving speeds of these shafts 117, 118 in connection with the spinning rotor 3 are controlled by a control means comprising a generator 110 which is driven by the motor 11 and an amplifier-101 which is connected to the generator 110 by way of a switch 86, a conductor 90, terminal 90a anda conductor 100, a third variable frequency electric source such as a generator 1 15 which generates an electrical output corresponding to the rotation speed of the driving shaft 117 or 118, a differential amplifier 109 which compares the outputs of the amplifier 101 and the generator 115, and a control motor 114 which controls the reduction ratio between the output speed of the motor 106 and the input speed of the variable speed power transmission means 116 so as to maintain the same at a predetermined value. The amplification degree of the amplifier 101 is so set that the output thereofis equal to the output of the generator 115. And the control motor 114 is actuated in accordance with the difference between the outputs of the amplifier 101 and the generators 115 so as to reduce the above-mentioned difference until it becomes zero. Therefore, the driving speed ratio of the feed rollers and the draw-off rollers in connection with the spinning roller during the yarn piecing operation can be maintained at the perspective predetermined values.

The engagements of the clutch means 96, 97 to the

respective gears

119 or 104, 120 or 105 are carried out as follows. That is, the clutch means 96 and 97 are engaged to the respective gears 119 and 120 during the normal spinning operation. When a yarn breakage is detected in a certain spinning unit (S), the connection of switches 84, 85 and 86 with the

common conductors

121, 122 and 123 connected to the respective elements of the first electric sources (E) are opened while these switches are connected to

respective conductors

88, 89 and 90 which are capable of being connected to respective terminals 88a, 89a and 90b of the second electric source (E and simultaneously, the clutch means 96 and 97 are disengaged from the respective gears 119 and 120. Consequently, the positive drive of the feed rollers and draw-off rollers is stopped. When the carrier 31 arrives at a working position in front of the spinning unit (S) wherein the yarn breakage was detected, the

conductors

88, 89 and 90 are connected to respective terminals 88a, 89a and 90a of the second electric source (E and simultaneously, the clutch means 96 and 97 engage the respective gears 104 and 105. Consequently, the feed rollers 1a, 1b draw-off rollers 5, 6 and the spinning rotor 3 of the spinning unit (S) are driven by the second electric source (E After completion of the yarn piecing operation, the driving speed of the motor 106 is increased up to a predetermined very high speed corresponding to the normal spinning condition. Then, the engagement of the elements to the second electric source (E is changed to the first electric source (E What is claimed is:

1. A method of driving an open-end spinning frame utilizing a plurality of spinning units each having a spinning rotor provided with a centrifugal rotary spinning cavity into which liberated fibers are continuously introduced to spin them into a yarn which is continuously delivered from the cavity, a pair of feed rollers supplying a bundle of fibers to said spinning rotor and a pair of draw-off rollers delivering said yarn from said rotor and a take-up roller making a package of said yarn delivered from. said draw-off rollers; comprising driving each spinning rotor, said feed rollers, said drawoff rollers and said take-up roller by means of individual motors respectively, driving said motors of all spinning units at a predetermined variable high speed by connecting said motors with a first common variable frequency electric source for carrying out a normal spinning operation, detecting yarn breakage of one individual spinning unit and driving said individual motors of a single spinning unit at a predetermined variable low speed by connecting said motors with a second variable frequency electric source mounted on a carrier displaceable along said spinning frame past said plurality of spinning units for carrying out a yarn piecing operation after disconnecting said motors from said first electric source, and after completion of said yarn piecing operation, driving said motors of said particular spinning unit at said high speed by connecting again with said first electric source.

2. Driving method of an open-end spinning frame according to claim 1, including carrying out said driving by said second electric source when a yarn breakage is detected during a travel motion of said carrier along said spinning frame.

3. Driving method of an open-end spinning frame according to claim 2, including commencing said high speed driving of all motors for driving respective rotors at a predetermined low speed and gradually accelerating said low'seed driving up to the predetermined high speed for carrying out normal spinning operations.

4. Driving method of an open-end spinning frame according to claim 1 including commencing said low speed driving of said motor of a spinning unit wherein a yarn piecing operation is required at a predetermined very low speed, and after completion of said yarn piecing operation, gradually accelerating said driving speed up to the predetermined high speed for carrying out normal spinning operations, thereafter changing said driving connection of said motor with said second variable frequency electric source to said first variable frequency electric source.

5. Driving method of an open-end spinning frame according to claim 1, including carrying out variable speed driving of said motor by said second variable frequency electric source together with variable speed driving of said feed rollers, draw-off rollers and take-up roller while maintaining relative speed ratios therebetween.

6. An apparatus for driving an open-end spinning frame utilizing a plurality of spinning units each having a spinning rotor provided with a centrifugal rotary spinning cavity into which liberated fibers are continuously introduced to spin them into a yam which is continuously removed from said cavity, a pair of feed rollers supplying abundle of fibers to said spinning rotor and a pair of draw-off rollers delivering said yarn from said rotor, a take-up roller for producing a package from said yarn delivered from said draw-off rollers, comprising respective individual motors for directly driving said spinning rotor, said feed rollers, said drawoff rollers, and said take-off roller of each spinning unit, means for driving said motors, said driving means comprising a first variable frequency electric source for driving all of said motors at a predetermined high speed for carrying out the normal spinning operation, a second variable frequency electric source for driving said motors of a spinning unit at a predetermined low speed to permit a yarn piecing operation, said second variable frequency electric source mounted'on a carrier, means for displacing said carrier along said spinning frame, means for connecting said motors of said spinning unit that has a yarn breakage to said second variable frequency electric source instead of said first electric source and again connecting said motors to said first electric source instead of said second electric source after completion of said yarn piecing operation.

7. Driving apparatus of an open-end spinning frame according to claim 6, wherein said first and second variable frequency electric sources are generators which are driven by respective variable speed motors.

8.' Driving apparatus of an open-end spinning frame according to claim 7, wherein said first and second variable frequency electric sources are static variable frequency electric sources.

9. Driving apparatus of an open-end spinning frame according to claim 8, wherein said static variable frequency electric source includes a plurality of semiconductor elements comprising thyristors.

10. Driving apparatus of an open-end spinning frame according to claim 6, further comprising a first mechanical driving means provided with a pair of shafts extending from said driving means through all spinning units, a second driving means provided with a pair of shafts extending through said carrier of said second electric source, said feed and take-off rollers each having drive shafts, and clutch means mounted on each spinning unit for engaging or disengaging said drive shafts of said feed roller and draw-off roller alternatively with respective shafts of said first electric source or second electric source.

l 1. Driving apparatus of an open-end spinning frame according to claim 6, further'comprising means for positioning said second electric source at a working position directly in front of a spinning unit wherein a yarn break is detected, means for engaging respective conductors for driving rotatable members of a spinning unit wherein the' yarn break is detected with corres onding terminals of said second electric source.

2. Driving apparatus of an open-end spinning frame according to claim 6, wherein said second electric source is provided with a control means for controlling the ratio of driving speeds of rotatable elements.

13. An apparatus for driving an open-end spinning frame utilizing a plurality of spinning units each having a spinning rotor provided with a centrifugal rotary spinningcavity into which liberated fibers are continuously introduced to spin them into a yarn which is continuously removed from said cavity, a pair of feed rollers supplying a bundle of fibers to said spinning rotor and a pair of draw-off rollers delivering said yarn from said rotor, a take-up roller for producing a package from said yarn delivered from said draw-off rollers, comprising individual motors for separately driving said spinning rotor, feeding rollers, draw-off rollers together with said take-up roller of each spinning unit, means for driving said motors, said driving means comprising a first variable frequency electric source for driving all of said rotatable members of said spinning frame at a predetermined high speed for carrying out the normal spinning operation, a second variable frequency electric source for driving said motors of a spinning unit at a predetermined low speed to permit a yarn piecing operation, said second variable frequency electric source mounted on a carrier, means for displacing said carrier along said spinning frame, means for connecting said motors of said spinning unit that has yarn breakage to said second variable frequency electric source instead of said first electric source and again connecting said motors to said first electric source instead of said second electric source after completion of said yarn piecing operation.

Claims

1. A method of driving an open-end spinning frame utilizing a plurality of spinning units each having a spinning rotor provided with a centrifugal rotary spinning cavity into which liberated fibers are continuously introduced to spin them into a yarn which is continuously delivered from the cavity, a pair of feed rollers supplying a bundle of fibers to said spinning rotor and a pair of draw-off rollers delivering said yarn from said rotor and a takeup roller making a package of said yarn delivered from said drawoff rollers; comprising driving each spinning rotor, said feed rollers, said draw-off rollers and said take-up roller by means of individual motors respectively, driving said motors of all spinning units at a predetermined variable high speed by connecting said motors with a first common variable frequency electric source for carrying out a normal spinning operation, detecting yarn breakage of one individual spinning unit and driving said individual motors of a single spinning unit at a predetermined variable low speed by connecting said motors with a second variable frequency electric source mounted on a carrier displaceable along said spinning frame past said plurality of spinning units for carrying out a yarn piecing operation after disconnecting said motors from said first electric source, and after completion of said yarn piecing operation, driving said motors of said particular spinning unit at said high speed by connecting again with said first electric source.

3. Driving method of an open-end spinning frame according to claim 2, including commencing said high speed driving of all motors for driving respective rotors at a predetermined low speed and gradually accelerating said low seed driving up to the predetermined high speed for carrying out normal spinning operations.

6. An apparatus for driving an open-end spinning frame utilizing a plurality of spinning units each having a spinning rotor provided with a centrifugal rotary spinning cavity into which liberated fibers are continuously introduced to spin them into a yarn which is continuously removed from said cavity, a pair of feed rollers supplying a bundle of fibers to said spinning rotor and a pair of draw-off rollers delivering said yarn from said rotor, a take-up roller for producing a package from said yarn delivered from said draw-off rollers, comprising respective individual motors for directly driving said spinning rotor, said feed rollers, said draw-off rollers, and said take-off roller of each spinning unit, means for driving said motors, said driving means comprising a first variable frequency electric source for driving all of said motors at a predetermined high speed for carrying out the normal spinning operation, a second variable frequency electric source for driving said motors of a spinning unit at a predetermined low speed to permit a yarn piecing operation, said second variable frequency electric source mounted on a carrier, means for displacing said carrier along said spinning frame, means for connecting said motors of said spinning unit that has a yarn breakage to said second variable frequency electric source instead of said first electric source and again connecting said motors to said first electric source instead of said second electric source after completion of said yarn piecing operation.

8. Driving apparatus of an open-end spinning frame according to claim 7, wherein said first and second variable frequency electric sources are static variable frequency electric sources.

9. Driving apparatus of an open-end spinning frame according to claim 8, wherein said static variable frequency electric source includes a plurality of semi-conductor elements comprising thyristors.

11. Driving apparatus of an open-end spinning frame according to claim 6, further comprising means for positioning said second electric source at a working position directly in front of a spinning unit wherein a yarn break is detected, means for engaging respective conductors for driving rotatable members of a spinning unit wherein the yarn break is detected with corresponding terminals of said second electric source.

12. Driving apparatus of an open-end spinning frame according to claim 6, wherein said second electric source is provided with a control means for controlling the ratio of driving speeds of rotatable elements.

13. An apparatus for driving an open-end spinning frame utilizing a plurality of spinning units each having a spinning rotor provided with a centrifugal rotary spinning cavity into which liberated fibers are continuously introduced to spin them into a yarn which is continuously removed from said cavity, a pair of feed rollers supplying a bundle of fibers to said spinning rotor and a pair of draw-off rollers delivering said yarn from said rotor, a take-up roller for producing a package from said yarn delivered from said draw-off rollers, comprising individual motors for separately driving said spinning rotor, feeding rollers, draw-off rollers together with said take-up roller of each spinning unit, means for driving said motors, said driving means comprising a first variable frequency electric source for driving all of said rotatable members of said spinning frame at a predetermined high speed for carrying out the normal spinning operation, a second variable frequency electric source for driving said motors of a spinning unit at a predetermined low speed to permit a yarn piecing operation, said second variable frequency electric source mounted on a carrier, means for displacing said carrier along said spinning frame, means for connecting said motors of said spinning unit that has yarn breakage to said second variable frequency electric source instead of said first electric source and again connecting said motors to said first electric source instead of said second electric source after completion of said yarn piecing operation.