Patent Description:
Conventionally, a device for applying tension to a yarn fed to a textile machine by a biasing force of a spring is known. For example, Patent Literature <NUM> discloses a device that is provided in a knotter device and applies a constant tension to a yarn by a biasing force of a spring. Furthermore, it is also known that a device adapted to apply tension to a yarn by a biasing force of a spring is provided in a flat knitting machine. Such devices are known for example in <CIT>, <CIT> or <CIT>.

However, since the device disclosed in Patent Literature <NUM> applies a constant tension to the yarn even in a state other than a yarn knotting operation, there is a problem that a load is applied to the yarn more than necessary. Therefore, a yarn tension applying device capable of controlling the tension applied to the yarn is desired.

The disclosure has been made in view of the above circumstances, and an object of the disclosure is to provide a yarn tension control device, a knotter device, and a flat knitting machine capable of controlling tension applied to a yarn.

The problem to be solved by the disclosure is as described above, and means for solving the problem will be described below.

In other words, a yarn tension control device according to the disclosure includes: a motor that generates a driving force; a cam configured to be rotatable by the driving force of the motor; a pair of yarn guides that guides a yarn to a predetermined position; a spring that generates a biasing force; and an arm that is freely-rocked and supported along a virtual plane passing between the pair of yarn guides, includes an insertion section through which the yarn guided by the pair of yarn guides is inserted and an action section on which the cam can act, is biased by the spring in a direction of applying a tension to the yarn, and rocks in a direction away from the pair of yarn guides with reference to a position where the biasing force of the spring and the tension of the yarn are balanced by an action of the cam on the action section to increase the tension applied to the yarn.

With such a configuration, the tension applied to the yarn can be controlled.

Furthermore, the arm decreases the tension applied to the yarn by rocking in a direction of approaching the pair of yarn guides with reference to the balanced position by an action of the cam on the action section.

With such a configuration, the tension applied to the yarn can be more finely controlled.

Furthermore, one end of the spring is fixed to the arm, and the other end of the spring is fixed to the cam.

With this configuration, the biasing force of the spring can be controlled.

Furthermore, the cam includes a first cam configured to be capable of acting on the action section of the arm, and a second cam to which the other end of the spring is fixed, and is configured to be capable of switching between the first cam and the second cam to change which one of the first cam and the second cam is to be rotated by the driving force of the motor.

With such a configuration, the biasing force of the spring can be controlled, and the tension applied to the yarn can be easily increased.

Furthermore, the cam includes a first cam configured to act on the action section of the arm and a second cam to which the other end of the spring is fixed, one of the first cam and the second cam is fixed to a motor shaft of the motor, and the other one of the first cam and the second cam is connected to the one of the first cam and the second cam with a differential gear interposed between the first cam and the second cam, and is configured to rotate in a direction opposite to the one of the first cam and the second cam along with rotation of the one of the first cam and the second cam.

Furthermore, a knotter device includes the yarn tension control device according to any one of claims <NUM> to <NUM>.

With such a configuration, the tension applied to the yarn can be changed before, during, and after a yarn knotting operation.

Furthermore, a flat knitting machine includes the yarn tension control device according to any one of claims <NUM> to <NUM>.

With such a configuration, the crossover of the yarn at the time of weft yarn inversion at a knitted fabric end can be suppressed from becoming long.

As an effect of the disclosure, the tension applied to the yarn can be controlled.

In the following description, directions indicated by arrows U, D, F, B, L, and R in the drawings are defined as an upward direction, a downward direction, a forward direction, a backward direction, a left direction, and a right direction, respectively. Furthermore, in the drawings, illustration of each component is appropriately omitted for simplification of illustration.

As illustrated in <FIG>, a yarn feeding mechanism <NUM> is configured to feed a yarn A used for knitting a knitted fabric from a yarn cone <NUM> to a flat knitting machine <NUM> through a knotter device <NUM>. In the yarn feeding mechanism <NUM>, the knotter device <NUM> is disposed downstream in a yarn feeding direction of the yarn cone <NUM>, and the flat knitting machine <NUM> is disposed downstream in the yarn feeding direction of the knotter device <NUM>.

In the flat knitting machine <NUM>, a yarn feeder <NUM> moves along a needle bed <NUM> in conjunction with a carriage <NUM>. A large number of knitting needles <NUM> are arranged in line on the needle bed <NUM>, and the knitting needles <NUM> advance and retreat to a tooth gap <NUM> to pull the yarn A from the yarn feeder <NUM> to knit a knitted fabric product C.

The knotter device <NUM> joins the yarn A being used in the flat knitting machine <NUM> and a new yarn A wound around the yarn cone <NUM>. The knotter device <NUM> includes a yarn selecting section <NUM> and a yarn joining section <NUM>.

The yarn selecting section <NUM> is configured to guide the yarn A selected from a plurality of the yarns A fed from the yarn cone <NUM> to the yarn joining section <NUM>. The yarn joining section <NUM> is configured to join the yarn A selected by the yarn selecting section <NUM> and the yarn A being used in the flat knitting machine <NUM>. The yarn joining section <NUM> is disposed downstream in the yarn feeding direction of the yarn selecting section <NUM>. The yarn joining section <NUM> includes a yarn tension control device <NUM>.

Hereinafter, a configuration of the yarn tension control device <NUM> will be described with reference to <FIG> and <FIG>. Note that a cam <NUM> and an arm <NUM> are rotatable or capable of rocked members, and the description will be made below with reference to positions illustrated in <FIG> and <FIG>.

The yarn tension control device <NUM> controls a tension of the yarn A when carrying out a yarn knotting operation. The yarn tension control device <NUM> includes a motor <NUM>, a motor base <NUM>, the cam <NUM>, a yarn guide <NUM>, the arm <NUM>, and a kick spring <NUM>.

The motor <NUM> generates a driving force. As the motor <NUM>, any motor can be used, but a stepping motor and a servo motor are suitable. The motor <NUM> includes a motor shaft 31a rotatable by the generated driving force. The motor <NUM> is disposed with an axial direction of the motor shaft 31a oriented in a vertical direction, and is provided so that a rotation amount and a rotation direction of the motor shaft 31a can be adjusted by a control unit (not illustrated).

The motor base <NUM> supports the motor <NUM>. The motor base <NUM> is formed in an appropriate shape capable of supporting the motor <NUM>, and is provided below the motor <NUM> so as to pass through the motor shaft 31a. The motor base <NUM> is provided with a pin 32a.

The pin 32a is provided to extend downward from a lower surface of the motor base <NUM> in the vicinity of a portion through which the motor shaft 31a is inserted. An end portion of the kick spring <NUM> described later is engaged with the pin 32a.

The cam <NUM> is configured to be rotatable by the driving force of the motor <NUM>. More specifically, the cam <NUM> is inserted into and fixed to a lower end of the motor shaft 31a below the motor base <NUM>, and is provided to rotate around an axis of the motor shaft 31a as the motor shaft 31a rotates. The cam <NUM> is formed in a substantially L-shaped plate shape, and is disposed with a plate surface facing the vertical direction. A first protrusion <NUM> and a second protrusion <NUM> are formed on the cam <NUM>.

The first protrusion <NUM> is a protrusion on one side of the two protrusions constituting the substantially L-shape of the cam <NUM>, and acts on a pin 38b of the arm <NUM> described later when the cam <NUM> rotates in a clockwise direction in the bottom view. The first protrusion <NUM> is formed to extend substantially rightward from a portion through which the motor shaft 31a is inserted to a position where the first protrusion can act on the pin 38b. A first pressing surface 35a facing the pin 38b is formed on the first protrusion <NUM>, and presses the pin 38b on the first pressing surface 35a when the cam <NUM> rotates in the clockwise direction in the bottom view.

The second protrusion <NUM> is a protrusion on the other side of the two protrusions constituting the substantially L-shape of the cam <NUM>, and acts on the pin 38b of the arm <NUM> described later when the cam <NUM> rotates in a counterclockwise direction in the bottom view. The second protrusion <NUM> is formed so as to extend substantially rearward from the portion through which the motor shaft 31a is inserted to a position where the second protrusion can act on the pin 38b. The second protrusion <NUM> is formed so as to extend in a direction substantially perpendicular to the first protrusion <NUM>. A second pressing surface 36a facing the pin 38b is formed on the second protrusion <NUM>, and presses the pin 38b on the second pressing surface 36a when the cam <NUM> rotates in the counterclockwise direction in the bottom view.

The yarn guide <NUM> is adapted to guide the yarn A to a predetermined position. The yarn guide <NUM> extends from the motor base <NUM> to the side (back side in the present embodiment) of the motor base <NUM>. A pair of the yarn guides <NUM> are disposed vertically. Hereinafter, the yarn guide <NUM> on an upper side may be referred to as a yarn guide 37A, and the yarn guide <NUM> on a lower side may be referred to as a yarn guide 37B. As illustrated in <FIG>, an insertion hole 37a is formed at a distal end of the yarn guide <NUM>, and the yarn A fed from the yarn cone <NUM> is inserted into the insertion hole 37a. The insertion hole 37a of the yarn guide 37A and the insertion hole 37a of the yarn guide 37B are formed at overlapping positions in the bottom view.

The arm <NUM> is adapted to change the tension applied to the yarn A guided by the yarn guide <NUM>. The arm <NUM> is a rigid body having a longitudinal rod shape and a plate shape, and is disposed with a plate surface facing the vertical direction. The arm <NUM> is inserted into and fixed to the motor shaft 31a, and is provided to rock around the axis of the motor shaft 31a. The arm <NUM> is disposed between the motor base <NUM> and the cam <NUM> and between the yarn guide 37A and the yarn guide 37B in the vertical direction, and is freely-rocked and supported along a virtual plane passing between the yarn guide 37A and the yarn guide 37B. The virtual plane is a plane that intersects with a line segment connecting the insertion hole 37a of the yarn guide 37A and the insertion hole 37a of the yarn guide 37B, and is a horizontal plane in the present embodiment. The arm <NUM> includes an insertion hole 38a and the pin 38b.

The insertion hole 38a illustrated in <FIG> is formed so as to vertically penetrate a distal end of the arm <NUM>, and the yarn A guided by the yarn guide <NUM> is inserted through the insertion hole. The insertion hole 38a is formed at a position where a distance in the plan view from an axial center of the motor shaft 31a to a center of the insertion hole 38a is the same as a distance in the plan view from the axial center of the motor shaft 31a to a center of the insertion hole 37a of the yarn guide <NUM>. Thus, the insertion hole 38a is formed at a position where the center of the insertion hole 38a can coincide with the center of the insertion hole 37a of the yarn guide <NUM> when the arm <NUM> is rocked.

The cam <NUM> can act on the pin 38b. An outer shape of the pin 38b is formed in a columnar shape and is provided to extend from a lower surface of the arm <NUM> to the same height as a lower surface of the cam <NUM> or below the lower surface of the cam <NUM>. The pin 38b is provided in the vicinity of the cam <NUM> in a longitudinal direction of the arm <NUM> and at a position not overlapping the cam <NUM> in the bottom view. More specifically, the pin 38b is provided between the first protrusion <NUM> and the second protrusion <NUM> in a circumferential direction around the axis of the motor shaft 31a in the bottom view. As described above, the pin 38b is provided at a position where the first pressing surface 35a of the first protrusion <NUM> and the second pressing surface 36a of the second protrusion <NUM> can abut on each other when the cam <NUM> rotates.

The kick spring <NUM> biases the arm <NUM>. The kick spring <NUM> is provided between the motor base <NUM> and the arm <NUM> such that the motor shaft 31a is inserted through a center portion of the kick spring <NUM>. One end of the kick spring <NUM> is fixed to the arm <NUM>, and the other end of the kick spring <NUM> is fixed to the pin 32a of the motor base <NUM>. The kick spring <NUM> thus disposed biases the arm <NUM> in a direction of applying a tension to the yarn A, more specifically, in a direction in which the arm <NUM> rocks counterclockwise in the bottom view. <FIG> illustrates a state in which the biasing force of the kick spring <NUM> applied to the arm <NUM> and the tension of the yarn A are balanced.

Hereinafter, an operation of each member of the yarn tension control device <NUM> when controlling the tension of the yarn A will be described with reference to <FIG>. The yarn tension control device <NUM> controls the tension applied to the yarn A when knotting the yarn A selected by the yarn selecting section <NUM> in the yarn joining section <NUM> and the yarn A being used in the flat knitting machine <NUM>. Hereinafter, before carrying out the yarn knotting operation is referred to as "before the yarn knotting operation", the middle of carrying out the yarn knotting operation is referred to as "during the yarn knotting operation", and the time when the knot is finally tightened in the yarn knotting operation is referred to as "end of the yarn knotting operation".

As illustrated in <FIG>, before the yarn knotting operation, the motor <NUM> is driven to rotate the cam <NUM> in the clockwise direction from a position illustrated in <FIG> to bring the first pressing surface 35a of the first protrusion <NUM> into contact with the pin 38b of the arm <NUM>. By further rotating the cam <NUM> in the clockwise direction in the bottom view, the first protrusion <NUM> presses the pin 38b of the arm <NUM> against the biasing force of the kick spring <NUM>, and rocks the arm <NUM> from a position illustrated in <FIG> in which the biasing force of the kick spring <NUM> applied to the arm <NUM> and the tension of the yarn A are balanced to a position where the center of the insertion hole 38a of the arm <NUM> coincides with the center of the insertion hole 37a of the yarn guide <NUM>, in the clockwise direction in the bottom view, that is, in a direction in which a distal end portion of the arm <NUM> approaches the insertion hole 37a of the yarn guides 37A and 37B in the plan view.

Thus, the yarn A can be guided to a position where the tension is not applied to the yarn A. Therefore, an unnecessary load can be prevented from being applied to the yarn A before the yarn knotting operation. Hereinafter, the position of the arm <NUM> illustrated in <FIG> is referred to as a "first position".

As illustrated in <FIG>, during the yarn knotting operation, the motor <NUM> is driven to rotate the cam <NUM> in the counterclockwise direction in the bottom view from the position illustrated in <FIG>, and the cam <NUM> is moved to the position where neither the first protrusion <NUM> nor the second protrusion <NUM> abuts on the pin 38b of the arm <NUM>. Then, the cam <NUM> does not act on the arm <NUM>, and only the biasing force of the kick spring <NUM> is applied to the arm. At this time, the arm <NUM> rocks by a predetermined angle in the counterclockwise direction in the bottom view from the first position illustrated in <FIG> by the biasing force of the kick spring <NUM>. Thus, the portion of the yarn A inserted through the insertion hole 38a of the arm <NUM> is pulled by the arm <NUM>.

Thus, the slack of the yarn A generated during the yarn knotting operation can be removed by the tension of the kick spring <NUM> applied to the yarn A during the yarn knotting operation. Hereinafter, the position of the arm <NUM> illustrated in <FIG> is referred to as a "second position".

As illustrated in <FIG>, at the end of the yarn knotting operation, the motor <NUM> is driven to rotate the cam <NUM> in the counterclockwise direction in the bottom view from the position illustrated in <FIG> to bring the second pressing surface 36a of the second protrusion <NUM> into contact with the pin 38b of the arm <NUM>. When the cam <NUM> is further rotated in the counterclockwise direction in the bottom view, the second protrusion <NUM> presses the pin 38b of the arm <NUM>, and rocks the arm <NUM> further from the second position illustrated in <FIG> in the counterclockwise direction in the bottom view, that is, in a direction in which the distal end portion of the arm <NUM> is separated from the insertion hole 37a of the yarn guides 37A and 37B in the plan view. Thus, the yarn A is forcibly pulled by the arm <NUM>.

Thus, the knot of the yarn A can be tightened by forcibly pulling the yarn A at the end of the yarn knotting operation. Hereinafter, the position of the arm <NUM> illustrated in <FIG> is referred to as a "third position".

As described above, the yarn tension control device <NUM> according to the present embodiment can change the tension applied to the yarn A according to each scene of the yarn knotting operation. Therefore, while reducing the load applied to the yarn A when the yarn knotting operation is not carried out, the slack of the yarn A can be removed or the knot of the yarn A can be strengthened when the yarn knotting operation is carried out. Furthermore, since the arm <NUM> is formed of a rigid body, it is possible to perform control with excellent responsiveness.

Although the first embodiment of the disclosure has been described above, the disclosure is not limited to the above embodiment, and appropriate modifications can be made within the scope of the technical idea of the disclosure described in the claims.

For example, in the present embodiment, the cam <NUM> causes the arm <NUM> to rock in the clockwise direction in the bottom view and in the counterclockwise direction in the bottom view by the two protrusions of the first protrusion <NUM> and the second protrusion <NUM>, but may cause the arm <NUM> to rock in the clockwise direction in the bottom view and in the counterclockwise direction in the bottom view by one protrusion. That is, the cam <NUM> does not necessarily have to include two protrusions, and may include one protrusion.

<FIG> illustrates a cam 33A which is a first different example of the cam <NUM>, and illustrates a state in which the biasing force of the kick spring <NUM> applied to the arm <NUM> and the tension of the yarn A are balanced. The cam 33A illustrated in <FIG> is different from the cam <NUM> illustrated in <FIG> in that the second protrusion <NUM> is not provided. In the cam 33A, in a case where it is desired to prevent a load from being applied to the yarn A before the yarn knotting operation, the cam 33A is rotated in the clockwise direction in the bottom view to press the pin 38b of the arm <NUM> by the first pressing surface 35a, similarly to <FIG>. As a result, the arm <NUM> can be rocked to the first position illustrated in <FIG>.

On the other hand, in a case where the yarn A is desired to be forcibly pulled out at the end of the yarn knotting operation, the pin 38b of the arm <NUM> is pressed by the second pressing surface 35b, which is a surface on an opposite side of the first pressing surface 35a of the first protrusion <NUM>, by rotating the cam 33A in the counterclockwise direction in the bottom view by nearly <NUM>° from the position illustrated in <FIG>. Thus, the arm <NUM> can be rocked to the third position illustrated in <FIG> to tighten the knot of the yarn A.

Furthermore, in the present embodiment, one end of the kick spring <NUM> is fixed to the arm <NUM>, and the other end of the kick spring <NUM> is fixed to the motor base <NUM>. However, the other end of the kick spring <NUM> may be fixed to the cam <NUM> instead of the motor base <NUM>. Consequently, the other end of the kick spring <NUM> is moved by rotating the cam <NUM>, so that the biasing force of the kick spring <NUM> applied to the arm <NUM> can be changed. Therefore, the tension applied to the yarn A during the yarn knotting operation can be controlled according to the ease of expansion and contraction of the yarn A, and the like.

Specifically, in a case where the tension applied to the yarn A by the kick spring <NUM> is too large due to the yarn A being relatively difficult to stretch, and the like, the cam <NUM> can be rotated so that the biasing force of the kick spring <NUM> decreases. On the other hand, in a case where the tension applied to the yarn A by the kick spring <NUM> is too small due to the yarn A being relatively easy to stretch, and the like, the cam <NUM> can be rotated so that the biasing force of the kick spring <NUM> increases.

However, in a case where the other end of the kick spring <NUM> is fixed to the cam <NUM>, when the cam <NUM> is rotated to press and rock the arm <NUM>, as the first protrusion <NUM> or the second protrusion <NUM> of the cam <NUM> approaches the pin 38b of the arm <NUM>, the arm <NUM> escapes due to the force of the kick spring <NUM>, and there is a problem that alignment of the arm <NUM> to the first position cannot be accurately performed. In order to solve this problem, a cam 33B illustrated in <FIG> can be configured.

<FIG> illustrates the cam 33B which is a second different example of the cam <NUM>, and illustrates a state in which the biasing force of the kick spring <NUM> applied to the arm <NUM> and the tension of the yarn A are balanced. The cam 33B illustrated in <FIG> is different from the cam <NUM> illustrated in <FIG> in that a third protrusion <NUM> is provided. In the cam 33B, the other end of the kick spring <NUM> is fixed to the first protrusion <NUM>. The third protrusion <NUM> is formed between the first protrusion <NUM> and the pin 38b of the arm <NUM> so as to extend substantially rightward from a portion through which the motor shaft 31a is inserted. A third pressing surface 46a facing the pin 38b is formed on the third protrusion <NUM>. The third pressing surface 46a is formed at a position closer to the pin 38b than the first pressing surface 35a of the first protrusion <NUM>.

In the cam 33B, since a distance from the pin 38b of the arm <NUM> to the third pressing surface 46a is shorter than a distance to the first pressing surface 35a, in a case where the cam 33B is rotated in the clockwise direction in the bottom view, the third pressing surface 46a can be easily brought into contact with the pin 38b before the arm <NUM> escapes. On the other hand, in a case where the cam 33B is rotated in the counterclockwise direction in the bottom view, the first protrusion <NUM> is separated from the arm <NUM>, and thus the biasing force of the kick spring <NUM> increases, and the tension of the yarn A increases with the increase in the biasing force. When the yarn A reaches a predetermined tension, the displacement of the angle of the arm <NUM> by the biasing force of the kick spring <NUM> is settled, but the yarn A can be forcibly pulled by the second protrusion <NUM> pressing the pin 38b to rock the arm <NUM> to the third position illustrated in <FIG>.

Furthermore, a sensor that measures the tension applied to the yarn A may be disposed, and the position of the arm <NUM> may be adjusted based on a measurement value of the sensor. Thus, the tension applied to the yarn A can be controlled to a desired value.

Furthermore, a motor capable of acquiring shaft torque may be used as the motor <NUM>, and the position of the arm <NUM> may be adjusted on the basis of a value of the shaft torque acquired by the motor <NUM>. Thus, the tension applied to the yarn A can be controlled to a desired value. Note that the shaft torque acquired by the motor <NUM> includes not only the tension applied to the yarn A but also the biasing force of the kick spring <NUM>. Therefore, it is preferable to provide a sensor that detects the position of the arm <NUM> so that a position of an end point of the kick spring <NUM> can be grasped by the sensor. Thus, since the change in the biasing force of the kick spring <NUM> can be grasped, the tension to be applied to the yarn A can be calculated by subtracting the biasing force of the kick spring <NUM> from the shaft torque acquired by the motor <NUM>.

Next, a yarn tension control device <NUM> according to a second embodiment will be described with reference to <FIG>, <FIG>. The yarn tension control device <NUM> according to the second embodiment differs from the yarn tension control device <NUM> according to the first embodiment mainly in that a lifting and lowering member 41a is disposed on a motor shaft 31a, and a first cam <NUM> and a second cam <NUM> are disposed instead of the cam <NUM>. Note that in <FIG>, <FIG>, a motor base <NUM> and a yarn guide <NUM> are not illustrated. Furthermore, the first cam <NUM>, the second cam <NUM>, and an arm <NUM> are rotatable or capable of rocked members, and hereinafter, the description will be made with reference to positions illustrated in <FIG> and <FIG>.

The lifting and lowering member 41a is formed in a hollow shape with one end opened, and is provided so as to enclose the motor shaft 31a. The cross-sectional shape of the opening portion of the lifting and lowering member 41a is similar to, but not limited to, the cross-sectional shape of the motor shaft 31a, for example, and the lifting and lowering member 41a is rotatable together with the motor shaft 31a and is provided to be vertically movable by a solenoid (not illustrated) provided below the lifting and lowering member 41a. A lower end of the lifting and lowering member 41a is formed in a shape capable of meshing with the first cam <NUM> and the second cam <NUM>. A lower end portion of the lifting and lowering member 41a is formed in, for example, a polygonal shape in the bottom view having a diameter larger than that of the other portion of the lifting and lowering member 41a, and is formed in, for example, a decagonal shape to a pentadecagonal shape in the bottom view.

The first cam <NUM> is for rocking the arm <NUM>, and is inserted into the lower end of the lifting and lowering member 41a. The first cam <NUM> is formed in a plate shape, and is disposed with a plate surface facing the vertical direction. A protrusion <NUM> is formed on the first cam <NUM>.

The protrusion <NUM> extends leftward and rearward from a portion through which the lifting and lowering member 41a is inserted to a position where the protrusion can act on a pin 38b of the arm <NUM>, and is formed to abut on the pin 38b when the first cam <NUM> rotates. The protrusion <NUM> is provided with a first pressing surface 55a and a second pressing surface 55b. When the first cam <NUM> rotates in the clockwise direction in the bottom view, the pin 38b is pressed on the first pressing surface 55a. When the first cam <NUM> rotates in the counterclockwise direction in the bottom view, the pin 38b is pressed on the second pressing surface 55b.

The second cam <NUM> is for controlling the biasing force of a kick spring <NUM>, and is inserted into the lifting and lowering member 41a above the first cam <NUM>. The second cam <NUM> is formed in a plate shape, and is disposed with a plate surface facing the vertical direction. A protrusion <NUM> is formed on the second cam <NUM>.

The protrusion <NUM> extends substantially rightward from a portion through which the lifting and lowering member 41a is inserted. The other end of the kick spring <NUM> is fixed to the protrusion <NUM>.

The lifting and lowering member 41a is provided so as to be vertically movable between a position at which its lower end meshes with the first cam <NUM> illustrated in <FIG> and a position at which its lower end meshes with the second cam <NUM> illustrated in <FIG>. When the lifting and lowering member 41a is located at the position illustrated in <FIG>, the first cam <NUM> can be rotated by driving the motor <NUM>. On the other hand, when the lifting and lowering member 41a is located at the position illustrated in <FIG>, the second cam <NUM> can be rotated by driving the motor <NUM>. As described above, the first cam <NUM> and the second cam <NUM> are configured to be capable of switching between the first cam <NUM> and the second cam <NUM> to change which one of the first cam <NUM> and the second cam <NUM> is to be rotated by the driving force of the motor <NUM>.

Next, an operation of each member of the yarn tension control device <NUM> when controlling the tension of the yarn A will be described with reference to <FIG>.

As illustrated in <FIG>, before the yarn knotting operation, the motor <NUM> is driven while the lifting and lowering member 41a is moved to the position illustrated in <FIG>, so that the first cam <NUM> is rotated in the clockwise direction in the bottom view and the pin 38b of the arm <NUM> is pressed by the first pressing surface 55a. As a result, the arm <NUM> can be rocked to the first position illustrated in <FIG>.

As illustrated in <FIG>, during the yarn knotting operation, the first cam <NUM> is rotated in the counterclockwise direction in the bottom view to a position where the protrusion <NUM> does not abut on the pin 38b of the arm <NUM>. Then, the arm <NUM> is rocked to the second position illustrated in <FIG> in the counterclockwise direction in the bottom view by the biasing force of the kick spring <NUM>, so that a portion of the yarn A inserted into the insertion hole 38a of the arm <NUM> is pulled by the arm <NUM>. Thus, the slack of the yarn A generated during the yarn knotting operation can be removed.

At this time, the second cam <NUM> can be rotated by driving the motor <NUM> in a state where the lifting and lowering member 41a is moved to the position illustrated in <FIG>. Thus, the biasing force of the kick spring <NUM> applied to the arm <NUM> can be changed, and eventually, the tension applied to the yarn A can be controlled when removing the slack of the yarn A.

Thus, by making the cam that presses the arm <NUM> and the cam to which the other end of the kick spring <NUM> is fixed separate members, the biasing force of the kick spring <NUM> can be made variable, and the forcible tension application to the yarn A by the pulling of the arm <NUM> can be independently carried out, so that both can be achieved.

As illustrated in <FIG>, at the end of the yarn knotting operation, the motor <NUM> is driven in a state where the lifting and lowering member 41a is moved to the position illustrated in <FIG>, and the first cam <NUM> is rotated in the counterclockwise direction in the bottom view, whereby the protrusion <NUM> presses the pin 38b of the arm <NUM>. Thus, the arm <NUM> can be rocked to the third position illustrated in <FIG>, and eventually, the knot of the yarn A can be tightened.

Although the second embodiment of the disclosure has been described above, the disclosure is not limited to the above embodiment, and appropriate modifications can be made within the scope of the technical idea of the disclosure described in the claims.

For example, in the present embodiment, in order to switch which one of the first cam <NUM> and the second cam <NUM> is rotated by the driving force of the motor <NUM>, the lifting and lowering member 41a is moved up and down by a solenoid or the like, but the first cam <NUM> and the second cam <NUM> may be moved up and down, respectively.

Next, a yarn tension control device <NUM> according to a third embodiment will be described with reference to <FIG> and <FIG>. The yarn tension control device <NUM> according to the third embodiment differs from the yarn tension control device <NUM> according to the first embodiment mainly in including a first cam <NUM> and a second cam <NUM> instead of the cam <NUM>, and including a differential gear <NUM>. Note that, in <FIG> and <FIG>, a motor base <NUM> and a yarn guide <NUM> are not illustrated.

The first cam <NUM> is for rocking an arm <NUM>, and is formed in the same shape as the first cam <NUM> of the second embodiment. A pressing surface 65a is formed on a protrusion <NUM> of the first cam <NUM>, and presses a pin 38b on the pressing surface 65a when the first cam <NUM> rotates in the counterclockwise direction in the bottom view.

The second cam <NUM> is for controlling the biasing force of a kick spring <NUM>, and is formed in the same shape as the second cam <NUM> of the second embodiment. The second cam <NUM> is fixed to a motor shaft 31a and is provided to rotate about the axis of the motor shaft 31a as the motor shaft 31a rotates. The other end of the kick spring <NUM> is fixed to a protrusion <NUM> of the second cam <NUM>.

The first cam <NUM> is coupled to the second cam <NUM> with the differential gear <NUM> provided to be interposed between the first cam <NUM> and the second cam <NUM>. As a result, the first cam <NUM> is configured to rotate in a direction opposite to a direction in which the second cam <NUM> rotates in accordance with the rotation of the second cam <NUM> by the driving force of a motor <NUM>.

In a case where it is desired to change the biasing force of the kick spring <NUM> during the yarn knotting operation, as illustrated in <FIG>, a position of the other end of the kick spring <NUM> is moved by rotating the second cam <NUM> by the driving force of the motor <NUM>, and the biasing force of the kick spring <NUM> can be changed. Specifically, by rotating the second cam <NUM> in the counterclockwise direction in the bottom view, the second cam <NUM> is separated from the arm <NUM>, so that the biasing force of the kick spring <NUM> increases. On the other hand, by rotating the second cam <NUM> in the clockwise direction in the bottom view, the second cam <NUM> comes close to the arm <NUM>, so that the biasing force of the kick spring <NUM> decreases.

In a case where it is desired to forcibly apply the tension to the yarn A at the end of the yarn knotting operation, as illustrated in <FIG>, the second cam <NUM> is rotated in the clockwise direction in the bottom view by the driving force of the motor <NUM>, so that the first cam <NUM> is rotated in the counterclockwise direction in the bottom view to bring the pressing surface 65a of the protrusion <NUM> into contact with the pin 38b of the arm <NUM>. By further rotating the first cam <NUM> in the counterclockwise direction in the bottom view, the protrusion <NUM> presses the pin 38b of the arm <NUM>, and further rocks the arm <NUM> in the counterclockwise direction in the bottom view. Thus, the arm <NUM> can be rocked to the third position illustrated in <FIG>, and eventually, the knot of the yarn A can be tightened.

In a case where it is not desired to apply the tension to the yarn A before the yarn knotting operation, the first cam <NUM> is rotated in the clockwise direction in the bottom view from the position illustrated in <FIG> by the driving force of the motor <NUM> as illustrated in <FIG>. When the first cam <NUM> rotates in the clockwise direction in the bottom view, the arm <NUM> rocks in the clockwise direction in the bottom view together with the first cam <NUM> in a state of being in contact with the first cam <NUM> by the biasing force of the kick spring <NUM>. As a result, the arm <NUM> can be rocked to the first position illustrated in <FIG>.

As described above, the yarn tension control devices <NUM>, <NUM>, and <NUM> according to the first to third embodiments of the disclosure are disposed in the knotter device <NUM>, but may be disposed in the flat knitting machine <NUM> as illustrated in <FIG>. Hereinafter, an example in which the yarn tension control devices <NUM>, <NUM>, and <NUM> are disposed in the flat knitting machine <NUM> will be described.

In the conventional flat knitting machine, when inlaying a knitting yarn from one of the left and right sides with the flat knitting machine, the tension becomes small at the time of reversing a yarn feeder at a knitted fabric end on a side far from a yarn tension control device provided in the vicinity of a side surface of the flat knitting machine. In particular, in a case where a high rigidity fiber is used as the inlay yarn, the tension application by spring biasing cannot follow a change in tension of the yarn, and there is a problem that the crossover of the inlay yarn at the time of reversal becomes long at the knitted fabric end on the far side.

Claim 1:
A yarn tension control device (<NUM>, <NUM>, <NUM>) comprising:
a motor (<NUM>) that generates a driving force;
a cam (<NUM>, 33A, 33B, <NUM>, <NUM>, <NUM>, <NUM>) configured to be rotatable by the driving force of the motor (<NUM>);
a pair of yarn guides (37A, 37B) capable to guide a yarn (A) to a predetermined position;
a spring (<NUM>) that generates a biasing force; and
an arm (<NUM>) that is freely-rocked and supported along a virtual plane passing between the pair of yarn guides (37A, 37B), the arm (<NUM>) being biased by the spring (<NUM>),
wherein the arm (<NUM>) includes an insertion section (38a) through which the yarn (A) guided by the pair of yarn guides (37A, 37B) can be inserted, characterized in that the arm (<NUM>) further includes an action section (38b) on which the cam (<NUM>, 33A, 33B, <NUM>, <NUM>) can act, the arm (<NUM>) being biased by the spring (<NUM>) in a direction of applying a tension to the yarn (A), and the arm (<NUM>) can be rocked in a direction away from the pair of yarn guides (37A, 37B) at a position where the biasing force of the spring (<NUM>) and the tension of the yarn (A) are balanced by an action of the cam (<NUM>, 33A, 33B, <NUM>, <NUM>) on the action section (38b) to increase the tension applied to the yarn (A).