Apparatus for drawing knitted fabrics

Abstract: A pair of nip rollers (4,5) and a rotating device for the nip rollers are provided at a position below an opening (3) between a pair of opposed, inclined needle beds (1,2). One of the nip rollers (4) is a fixed-position roller, and the other nip roller (5) is pivotally supported by a pivotable arm (19). A spring (31) pulled by rotation of a shaft (27) driven by a motor is connected to the pivotable arm (19). The pulling force exerted by the spring (31) on the pivotable arm is controlled by rotation of the motor, whereby the roller (5) provided on the pivotable arm (19) is movable into adjustable pressure contact with the fixed-position roller (4).

Description: The present invention relates to an apparatus for holding and drawing down knitted fabrics. An apparatus for drawing knitted fabrics is known in which knitted fabrics are held by a pair of rolls provided at a position below an opening of a 2-bed knitting machine, and the knitted fabrics are drawn down by rotating the rolls. In the aforesaid apparatus, a torque motor is used as the means for rotating the rolls. In the conventional knitting machine, the surface pressure between the front and rear rollers provided in paired relationship is constant, and therefore the force drawing down the knitted fabrics is either adjusted by varying the torque of the motor or else the surface pressure can be adjusted once by hand prior to knitting. In this known machine, the force drawing down the knitted fabrics when the fabrics are being knitted can be adjusted only by controlling the output of the torque motor. EP-A-0268187 describes another apparatus for drawing down knitted fabrics, in which pressure rollers are pivotally movable into contact with a fixed-position roller or rollers by motorised means. In order to achieve an automatically adjustable, reproducible, uniform drawing down, the pressure rollers are pivotable jointly by a motor drive into and out of variable end positions and the pressure force of each pressure roller is individually adjustable by means of a motor drive. It is an object of the present invention to provide an apparatus in which adjustment of the surface pressure, including opening and closing, between paired nip rollers is effected by the use of a drive system which is separate from a drive system for controlling rotation of rollers to adjust the drawing down force of knitted fabrics. In accordance with the invention there is provided an apparatus for drawing down knitted fabrics comprising a fixed-position roller, a pressure roller, drive means for said rollers, a pair of opposed, inclined needle beds having an opening therebetween, the pressure roller being pivotably supported by at least one pivotable arm, and a pivot mechanism controlling movement of said at least one pivotable arm thereby to bring said pressure roller into pressure contact with the fixed-position roller, characterised in that the rollers and their drive means are positioned below said opening between the needle beds, and in that said pivot mechanism comprises a cam, a motor for rotating the cam, spring means connected at one end to the cam and coupled at the other end to said at least one pivotable arm, and a roller provided at the end of the or each pivotable arm remote from the pressure roller for following the cam, such that rotation of the cam by the motor controls the force exerted by the spring means on the pivotable arm or arms and thus the pressure between the pressure roller and the fixed-position roller. One embodiment of apparatus according to the present invention will now be described by way of example and with reference to the drawings. In the drawings: Fig. 1 is a side view taken on line I-I of Fig. 3 showing a drive system of rollers; Fig. 2 is a developed view of the same; Fig. 3 is a sectional view taken on line III-III of Fig. 1; Fig. 4 is a sectional view taken on line IV-IV of Fig. 1, and Figs. 5 and 6 are side views showing the operating state of a pivotal arm. Nip rollers 4 and 5 are provided at a position below an opening 3 between the upper ends of opposed needle beds 1 and 2. The upper ends of the needle beds 1, 2 are directed towards a peak. The two nip rollers 4 and 5 are provided to nip knitted fabrics. The one nip roller 4 is rotatably supported by end brackets 6 and 7 and is connected to a shaft of a motor 16 through a timing pulley 9 provided at the end of a roller shaft 8, a timing belt 10, timing pulleys 13, 13 of an intermediate shaft 11, a timing belt 14 and a timing pulley 15. To the intermediate shaft 11 is secured a gear 17 for transmitting rotation to the other nip roller 5. The nip roller 5 is supported at the top of pivotal arms 19 and 19 pivotably mounted on a shaft 18 supported on the end brackets 6 and 7. The nip roller 5 is moved towards and away from the nip roller 4 by pivotal motion of the pivotal arms 19 and 19 about the shaft 18 to nip a knitted fabric F therebetween. A shaft 23 having a gear 21 and a pulley 22 is supported on a frame 20. The gear 21 is meshed with the gear 17. Upon reception of rotation from the gear 17, the nip roller 5 is rotated through a timing pulley 22, a belt 24, a timing pulley 25 and a roller shaft 26. Since the same pivot mechanism is used for the two pivotal arms 19 and 19, the pivot mechanism for the pivotal arm 19 shown in the left-hand side of Fig.1 will be described hereinafter. A cam 28 is supported on the end of a shaft 27 supported on the brackets 6 and 7 (Fig.1). Pins 29 and 30 are mounted on the side of the cam 28 and on the side of the pivotal arm 19 respectively, and a spring 31 extends between the two pins 29 and 30. The spring 31 is wound around the shaft 27 between the pins 29 and 30. Accordingly, the cam 28 is rotated by rotation of the shaft 27 to vary the wound length of the spring, that is the tractive force of the spring 31, and therefore the pivotal arm 19 is pulled so as to be rotated counterclockwise as shown in Fig. 3 under the tension appropriate to the varied length of the spring and the nip roller 5 provided at the top of the pivotal arm is moved into pressure contact with the nip roller 4. This pressure contact is caused by the spring 31. A roller 32 is provided at the lower portion of the pivotal arm 19 (Figs. 3 to 6). The roller 32 is at a position capable of contacting the cam 28, and when the cam face 33 comes into contact therewith by rotation of the cam 28 in the counterclockwise direction as shown in Fig. 3, it is urged by the cam face 33 to rotate the pivotal arm 19 clockwise and to move the nip roller 5 away from the nip roller 4. A half-moon shaped gear 35 for rotating the shaft 27 is provided at the end of the shaft 27. This gear 35 (shown in Figs. 1 and 4) meshes with a gear 38 provided on a motor shaft 37 of a torque motor 36 to receive power transmitted from the motor 36. A stop pin 39 is provided on the bracket 6 so as to be positioned at a portion of the gear 35 in which no tooth is present in order to control the limit of rotation of the gear 35. In drawing the knitted fabric F by the apparatus according to the present invention, the knitted fabric F is nipped between the nip rollers 4 and 5 in the condition where the nip rollers 4 and 5 are placed in pressure contact with each other. The rotation of the motor 16 is transmitted to the nip roller 4 through the pulley 15, belt 14, pulley 13, shaft 11, pulley 12, belt 10, and shaft 8 of the pulley 9, whereas the rotation of the shaft 11 is transmitted to the nip roller 5 through the gears 17, 21, shaft 23, pulley 22, belt 24, pulley 25 and roller shaft 26 to rotate the nip roller 5. In this manner, the knitted fabric F is nipped between and drawn down by the nip rollers 4 and 5. Adjustment of the nip pressure is carried out in the following manner. When the nip pressure is to be applied most strongly, the motor 36 is rotated, rotation of which is transmitted to the cam shaft 27 through the gears 38 and 35, and the cam shaft 27 is rotated clockwise as shown in Fig. 3 and counterclockwise as shown in Fig. 4. The aforesaid rotation becomes a maximum when the end 40 of a portion of the gear 35 in which no tooth is present comes into contact with the stop pin 39, and at this time the nip pressure is at its maximum. When the end 40 of the gear comes into contact with the stop pin 39, the motor 36 is still driven, but in the case where a torque motor is used that rotation can be stopped. In the case where a stepping motor or the like is used, if the number of steps is set in advance, rotation of the motor can be stopped at a contact position between the gear end 40 and the stop pin 39. Upon rotation of the motor shaft 37, the cam 28 integral with the cam shaft 27 rotates, the pin 29 mounted on the cam 28 pulls the spring 31 engaged therewith, the pivotal arm 19 is pivoted about the shaft 18 by the force of the spring 31, and the nip roller 5 at the extreme upper end of the arm is placed under increased pressure contact with the other nip roller 4. The nip pressure is determined according to the angle through which the shaft 27 is rotated. Therefore, when one wishes to change the nip pressure, the motor 36 is suitably rotated to effect rotation of the cam 28 and change the force exerted by the spring 31. In changing the nip pressure as described above, in the case where knitted fabrics are subjected to shaping knitting or in the case where knitted fabrics which are different in texture are continuously knitted, a different drawing force has to be initiated according to the part of the knitted fabric being knitted. In such a case, if rotation of both the motors 16, 36 is controlled in the knitting step stored in advance, the knitted fabric can be automatically drawn down at a suitable speed. In summary, the apparatus for drawing knitted fabrics according to the present invention provides an arrangement wherein a pair of nip rollers and rotating means for said nip rollers are provided at a position below an opening between a pair of opposed needle beds, one of said rollers being a fixed-position roller, the other of said rollers being pivotably supported by at least one pivotal arm, a spring pulled by rotation of a shaft of a motor is mounted about the or each pivotal arm, and the pulling force exerted by the spring or springs on the pivotal arm or arms is controlled by rotation of the motor, whereby said other roller is a pressure roller movable into pressure contact with the fixed-position roller. The nip pressure can be controlled independently of the rotational speed of the nip roller. In particular, by making the nip pressure adjustable, since the drawing force of knitted fabrics is varied by the spring, fine adjustment of the drawing force can be achieved. Furthermore, if the width, texture or the like of the fabric to be knitted is changed, it is only necessary to vary the turning force of rollers, which can be done by the apparatus of the present invention. Moreover, since the nip pressure adjusting motor controls opening and closing of the nip rollers, the optimum drawing force can be obtained for a variety of knitted textures by a combination of opening and closing of rollers or the like.

Claims: An apparatus for drawing down knitted fabrics (F) comprising a fixed-position roller (4), a pressure roller (5), drive means for said rollers, a pair of opposed, inclined needle beds (1,2) having an opening (3) therebetween, the pressure roller (5) being pivotably supported by at least one pivotable arm (19), and a pivot mechanism controlling movement of said at least one pivotable arm thereby to bring said pressure roller (5) into pressure contact with the fixed-position roller (4), characterised in that the rollers (4,5) and their drive means are positioned below said opening (3) between the needle beds, and in that said pivot mechanism comprises a cam (28), a motor (36) for rotating the cam, spring means (31) connected at one end to the cam and coupled at the other end to said at least one pivotable arm (19), and a roller (32) provided at the end of the or each pivotable arm (19) remote from the pressure roller (5) for following the cam (28), such that rotation of the cam by the motor (36) controls the force exerted by the spring means (31) on the pivotable arm or arms (19) and thus the pressure between the pressure roller (5) and the fixed-position roller (4).

Inventors: IKOMA KENJI, SHIMA MASAHIRO, IKOMA, KENJI, SHIMA, MASAHIRO
Applicants: SHIMA SEIKI MFG, SHIMA SEIKI MFG., LTD.
Application year: 1990
Main classification: D04B15
IPC codes: D04B15