JPH0811851B2 - Method and device for preventing resonance of weft measuring device in loom - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and a device for preventing resonance of a weft measuring device in a loom, and in particular, weft is wound around a stationary drum and stored, and each weft insertion is performed. The present invention relates to prevention of resonance of a weft measuring device of a type in which a weft of a length necessary for the weaving is fed (prior art). Various devices have been conventionally used as a device for stopping a drum in a weft measuring device of a loom. Has been. Among them, the most recent trend is that a magnet is provided on the drum and a fixed portion of the weft measuring device facing the drum so as to face each other, and the drum is stopped by the attractive force of the magnet.

 Examples thereof are disclosed in JP-A-58-36244, JP-B-59-169381, and JP-A-58-70748.

(Problems to be solved by the invention) However, in all of these conventional devices, the relationship between the relative magnetic force of the drum and the magnetic force of the fixing portion of the weft measuring device is kept constant, and therefore, The natural frequency of the weft length measuring device represented by is fixed. Where f is the natural frequency of the weft length measuring device, k is the spring constant determined by the opposing magnetic force between the drum support plate and the fixed part of the weft length measuring device, m is the mass of the drum and its supporting plate, and therefore the operating conditions of the loom, For example, when the number of revolutions, the fabric, the type of yarn, etc. change, the natural frequency of the weft length measuring device does not match the operating conditions (for example, when the ratio to the forced frequency of the loom body approaches 1), resonance occurs. A phenomenon may occur, which may cause the drum to rotate and prevent the drum from maintaining a reliable stationary state, which lacks reliability as a stationary device for the drum.

In the weft yarn length measuring device, the weft yarn is supplied from a guide member rotating around the drum and wound around the drum a predetermined number of times.
The length of the weft yarn necessary for one weft insertion is defined by the circumferential length of the drum and the number of times the yarn is wound around the drum.
Therefore, if the drum is not securely stopped, that is, if the drum is rotated in any direction even a little, a difference in the length measurement of the weft occurs. In particular, if there is such a difference in the length measurement of the weft in the jet room, the weft may not reach the predetermined position during weft insertion, or a weft insertion error may occur, or the weft may fly over the predetermined position. However, there is a problem that the weft insertion length varies, such as waste of paper.

(Object of the Invention) It is an object of the present invention to provide a method and an apparatus capable of reliably stopping a drum so as to eliminate the above-mentioned drawbacks and to accurately measure the length of a weft yarn necessary for each weft insertion. It is intended.

(Means for Solving the Problems) In order to solve the above-mentioned drawbacks, in the present invention, it is possible to have two or more kinds of natural frequencies in order to avoid resonance of the weft measuring device. Then, a method of changing the magnetic force between the magnet attached to the drum portion and the magnet attached to the fixed portion surrounding the drum was adopted. Further, in the second invention, a plurality of magnet groups are provided on the support plate to which the drum is attached, and a plurality of magnet groups different in number from the magnet groups on the support plate are also provided in the fixed portion facing the magnet group. It is arranged such that the support plate is rotated by a certain angle on its support shaft, and the number of magnets facing each other between the fixed part and the drum support plate part can be changed.

(Operation) In the present invention, when a resonance phenomenon occurs due to a change in operating conditions, the resonance can be prevented by changing the magnetic force of the facing magnet.

Embodiment An embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

A rotary support shaft 3 is rotatably mounted at an upper end of a side frame 1 of a loom through a radial bearing 2, and a weft supply portion (not shown) for cheese or the like is attached to the support shaft 3.
A guide hole 3a for guiding the weft Y supplied from is provided along the axis thereof. A toothed pulley 4 is fixed to the base end side of the rotation support shaft 3, and a timing belt 5 is attached to the pulley 4. The belt 5 is driven in synchronization with the weaving operation to rotate the rotation support shaft 3. A thread winding tube 6 is attached to an intermediate portion of the rotary support shaft 3 so as to communicate with the weft thread guide hole 3a, and its tip is opened near the thread winding surface described later.

A support 7 is rotatably supported on the tip side of the rotary support shaft 3, and a disc-shaped support plate 8 is fixed to the front surface (right side in FIG. 1) of the support 7. A drum 9 is attached to the front surface of the support plate 8.

As shown in FIG. 2, the drum 9 has a plurality of divided pieces a to
It is composed of d and forms a weft measuring unit. On one side surface of each of the divided pieces a to d, there is provided a hole 12 through which locking pins 10 and 10 'for storing the weft yarn are stored until they are released. Locking pins 10 and 10 'are mounted on the upper ends of locking levers 11 and 11' which swing about 13 as a fulcrum, and through the cam 15 and the cam follower 14, the holes of the drum divided pieces are alternately arranged at a predetermined timing. The weft yarn wound on the drum is measured by the yarn winding tube 6 which enters and exits at 12, and is stored.

A bracket 19 for receiving a bearing is attached to the side frame 1, and a magnet case 16 is attached to the front surface of the bracket. On the inner peripheral surface of the magnet case and the outer peripheral surface of the front support plate 8, magnet groups 17 and 18 having an attraction relationship are provided to face each other.

Therefore, the timing belt 5 is driven to rotate the rotary support shaft 3.
When is rotated, the thread winding tube 6 rotates integrally with the support shaft 3 and the stationary state is maintained without rotating the support plate 8 by the attraction action of the magnet groups 17 and 18. As a factor that changes the stationary state, the unwinding resistance of the weft thread wound around the length measuring drum and the resonance phenomenon of the weft length measuring apparatus due to the vibration applied from the loom body are considered. In this case, the rotation of the support plate 8 due to the unwinding resistance of the weft can be prevented by increasing the magnetic force of the magnet groups 17, 18 above the unwinding resistance of the weft.

Next, the resonance phenomenon will be described. The natural frequency of the weft length measuring device is given by the following equation as described above.

On the other hand, the external forced vibration applied to the weft measuring device includes vibration from the loom body, and the frequency N is Given in.

n: Number of revolutions per minute of the loom Here, when N / f≈1, the so-called resonance phenomenon is induced and the vibration of the weft length measuring device is extremely increased, so that the supporting plate 8
Is unable to maintain a stationary state and rotates, making normal weft insertion impossible.

One way to avoid this resonance phenomenon is to change the natural frequency f of the weft length measuring device.

To change f, k or m in the above formula (1) may be changed. The change of m requires changing the parts of the length-measuring body, which causes drawbacks such as replacement of parts, increase in cost, or increase in inertial force due to increase in mass.
According to the present invention, as a means for easily changing f and preventing the resonance phenomenon, the spring constant generated by the magnetic force between the support plate provided with a fixed number of magnet groups and the magnet group of the fixed part of the weft measuring device facing the support plate. is to change k.

A specific example will be described with reference to the drawings. As a method of changing k, there are (1) a method of changing the magnetic force by changing the number of facing magnet groups, and (2) a method of changing the magnetic force by replacing the magnet. As for the apparatus according to the present invention, the proposal (1) is taken into consideration in consideration of the maintainability and economy of the weft measuring apparatus. 2 to 4 are front views of the weft length measuring device as viewed from the weft traveling direction. Second
In the figure, there are a total of 9 sets of magnets, 6 sets on the left and 6 sets on the right and left with the support shaft 3 as the center. Further, in FIG. 3, the magnetic force of the total number of the magnets, which is 9 and 6, is 15 in total to prevent the support plate 8 from rotating. If the operating conditions of the loom change here,
Resonance phenomenon may be induced, and as a method of preventing it, the number of magnets that are relatively moved is changed to change the natural frequency of the weft length measuring device. In FIG. 1, the support plate 8 and the support plate 7 are screwed together by a screw 20, and are supported on the support shaft 3 via a ball bearing 21. The procedure for rotating the support plate 8 is as shown in FIG. 2 by removing the locking pin 10 which is in the locking pin entrance hole 12 of the drum divided piece from the locking lever 11 and connecting it to the weft measuring device fixing portion. The support plate 8 in the stationary holding state by the magnetic force is manually overcome to rotate the support plate 3 clockwise by 180 degrees on the support shaft 3, and the locking pin 10 is attached to the locking lever again. Fig. 4 shows the state in which the support plate in Fig. 3 is rotated clockwise by 180 degrees, and the number of magnets that make up relative to each other is 6 sets on each of the left and right, totaling 12 sets, and the magnetic force is proportional to the number of sets. The magnetic force of one set changes to the magnetic force of 12 sets. As a result The value of k changes and the value of f also changes, and the ratio between the forced frequency N and f applied from the loom main body becomes far from 1, so that the resonance phenomenon can be prevented. In the case of FIG. 2 as well, if it is rotated 180 degrees in the same manner, the number of magnet pairs that face each other is three on each of the left and right sides, for a total of six, and resonance phenomena can be prevented. The present invention is not limited to the above embodiment, but an electromagnet may be used and its magnetic force may be changed.

(Effect) As described in detail above, according to the present invention, the natural frequency of the weft measuring device is changed by a simple method of rotating the support plate provided with the magnet on the support shaft, and the operating condition of the loom is changed. This has the effect of preventing the resonance phenomenon that occurs when there is a change and maintaining the stationary state of the support plate and the drum for reliable weft insertion.

[Brief description of drawings]

FIG. 1 is a schematic side sectional view showing an embodiment embodying the present invention, FIG. 2 is a sectional view taken along the line AA of FIG. 1, and FIG. 3 is a case where the number of magnet sets is different from that of FIG. FIG. 4 is a cross-sectional view of the case where the magnet group of the weft length measuring device fixing portion and the supporting plate facing the weft measuring device are rotated clockwise by 180 degrees to change the number of magnets facing each other. 1 ... Side frame, 2 ... Ball bearing 3 ... Rotating support shaft, 3a ... Weft guide hole Y ... Weft, 5 ... Timing belt 6 ... Thread winding tube, 7 ... Support 8 ... Support Plate, 9 ... Drum I ~ D ... Drum split piece, 10, 10 '... Weft Locking pin, 11, 11' ... Locking lever 12 ... Locking pin entry hole, 13 ... Locking lever Support point 14 …… Cam follower, 15 …… Cam, 16 …… Magnet case,
17, 18 …… Magnet 19 …… Bearing placket, 20 …… Screw 21 …… Ball bearing

Claims (2)

[Claims] 1. A weft measuring device of a loom, wherein a weft is wound around a stationary drum and stored, and a weft of a required length is fed out each time the weft is inserted. A resonance preventing method, characterized in that a magnetic force between a magnet attached to the drum portion and a magnet attached to a fixing portion surrounding the drum is changed in order to change the number. 2. A weft measuring device of a loom, wherein wefts are wound and stored on a drum in a stationary state, and a required weft yarn is fed out each time weft is inserted. And a plurality of magnet groups different in number from the magnet groups on the support plate are also installed on the fixed portion facing the magnet group, and the support plate is rotated by a certain angle on the support shaft. A resonance preventing device, wherein the number of magnet pairs facing each other between the fixed portion and the drum support plate portion can be changed.