JPH0327659B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a weft supply preparation method in a jet room such as an air jet room or a water jet room. More specifically, the present invention relates to a method for preparing a weft yarn for supply in a drum pool type jet loom, in which the weft yarn unwound from the weft cheese is stored on a weft length measuring drum and inserted by a jet nozzle.

The weft measuring drum of the present invention may be of the type in which the drum rotates and the weft is wound around its circumference and stored, or the drum may be stationary and the weft winding tube (winding arm) rotates around it. It may be of any type in which the weft is wound and stored.

[Conventional technology]

The drum pool type weft storage device must rotate in complete synchronization with the crankshaft of the loom body, and cannot rotate in reverse. If synchronization with the crankshaft is not achieved, a predetermined length of weft yarn cannot be inserted at a predetermined timing, resulting in a weft insertion error. Also, if the drum etc. is rotated in the opposite direction,
The wound weft becomes disordered and weft insertion becomes impossible.

A loom may stop operating due to yarn breakage or other causes. In such a case, restart the machine after removing the cause of the stoppage. Even in that case, the drum pool type weft storage device needs to rotate in complete synchronization with the crankshaft of the loom main body for the reasons mentioned above, and cannot rotate in the opposite direction.

[Problem that the invention seeks to solve]

Japanese Unexamined Patent Publication No. 59-125943 discloses that when a loom stops operating due to thread breakage or other reasons, the weft is wound around a drum-type weft pool device, and almost all of the weft necessary for one pick weft insertion is collected. A method is disclosed that can automatically store.

In this method, when a weaving abnormality occurs, the machine is stopped (crank angle I = approximately 300 degrees), the connection between the drive system of the weft length measuring drum and the crankshaft of the loom is cut off, and the drive system of the weft length measuring drum is assisted. The machine can be driven by a motor, and the machine is reversed so that the crank angle matches the above-mentioned crank angle while processing mistakes using the mistake thread processing method disclosed in JP-A No. 58-197339. and set the weft length measuring drum to a suitable position for threading by the auxiliary motor,
The weft end is threaded onto the weft length measuring drum at the appropriate position, and then the auxiliary motor rotates the weft length measuring drum in a predetermined manner to store a predetermined amount of weft on the weft length measuring drum.

In order to perform the above weft preparation method reliably, it is necessary to match the crank angle I when the machine is stopped with the crank angle of the machine before storing the weft in the weft measuring drum, and It is necessary to synchronize the timing of each part.

However, in reality, it is very difficult to stop the loom by making the crank angle after reversing the loom match the crank angle when the loom is stopped, and forcing the loom to match will cause the equipment to It becomes complicated and equipment costs are high. Therefore, the amount of rotation of the drum by the auxiliary motor is adjusted depending on the relationship between the crank angle after the loom is reversed and the crank angle when the loom is stopped. In other words, if the crank angle after reversing the loom is later than the crank angle when the loom is stopped, rotate the weft length measuring drum by the difference between the two angles, -, and change the crank angle after reversing the loom. is ahead of the crank angle when the loom is stopped, the weft length measuring drum can only rotate in the forward direction, so the weft length measuring drum is rotated by an angle close to one revolution of the loom, and the One pick's worth of weft stored in the weft measuring drum is removed.

As mentioned above, it is very difficult to match the crank angle after the loom is reversed with the crank angle when the loom is stopped, and if you try to force it to match, the equipment becomes very complicated and equipment costs are high. becomes.

In addition, in order to control the rotation of the weft length measuring drum according to the relationship between the crank angle after reversing the loom and the crank angle when the loom is stopped, the amount of rotation of the weft length measuring drum is adjusted according to the stop position. Control becomes complicated. Moreover, in addition to weft insertion errors, there are other abnormalities during weaving, such as feeding errors in which the weft is not fed to the main nozzle, warp thread breakage, and selvedge thread breakage, and different measures should be taken depending on these abnormalities. Operators may make operational errors, resulting in longer operation times and poor quality of the resulting woven fabric.

[Purpose of the invention]

The present invention solves the problems associated with the above-mentioned prior art, eliminates the need to delicately control the stop position of the loom, eliminates the need for a complicated and expensive device for controlling the stop position, and also eliminates the need for weft yarn supply. The same operation can be used to deal with mistakes or errors in weft insertion, eliminating operator errors and making it possible to weave high-quality fabrics.
Moreover, it is an object of the present invention to provide a weft supply preparation method that can shorten the abnormal processing time when an abnormal stop occurs.

[Means for solving problems]

In the present invention, the above-mentioned object is achieved by winding and storing the weft yarn for at least one pick on the storage surface of the weft length measuring drum using the driving force from the crankshaft of the loom.
While the machine is operating, the length of the weft for one pick is measured and inserted using a weft locking pin that can move toward and away from the storage surface, and when a stop signal from the main motor is generated, the next weft is inserted. The loom is stopped by inertial operation while being constantly blocked, and after the loom is stopped, the drive system of the weft length measuring drum is disconnected from the crankshaft, the loom is reversed by the crankshaft, and the auxiliary motor is used to measure the weft. In a weft supply preparation method in which a predetermined amount of weft is stored on the weft length measuring drum by driving the drive system of the weft length measuring drum, the drive system of the weft length measuring drum is activated by an auxiliary motor between the machine stop and restart. to remove at least one pick of weft stored in the weft length measuring drum, and then connect the crankshaft and the weft length measuring drum in phase to restart the loom. This is achieved by a characteristic weft supply preparation method.

[Effect]

In the present invention, regardless of the relationship between the crank angle after reversing the loom and the crank angle when the loom is stopped, that is, if the crank angle after reversing the loom is behind the crank angle when the loom is stopped. In the same way, even when the weft is progressing, the weft length measuring drum drive system is rotated at least by an angle equivalent to one rotation of the machine, and before rotation, the weft yarn stored in the drum for one pick is measured. There is no need to delicately control the stop position of the loom as in the prior art, and a complicated and expensive device for controlling the stop position can be eliminated.

Moreover, according to the present invention, weft feeding errors, especially
If the weft yarn is wrapped around the weft length measuring drum, cut and remove the wrapped weft yarn, pass the weft yarn from the winding arm of the length measuring drum to the main nozzle via the gripper, and remove the suction means etc. at the main nozzle outlet. When the start button is turned on, the drive system of the weft measuring drum rotates and one pick's worth of weft is stored on the measuring drum. Even in the event of a weft supply error, the operation is the same as in the case of a weft insertion error. This eliminates the need for winding one pick of weft yarn around the drum, eliminates operator errors, allows for weaving of high-quality fabrics, and shortens the processing time for abnormal stoppages. Can be done.

〔Example〕

Hereinafter, the present invention will be explained in detail with reference to the drawings. FIG. 1 is a schematic plan view of an air jet room in which the present invention is implemented, and the crankshaft of the loom is driven by a belt from a main motor. Further, the crankshaft is connected to a winding arm 28a of a weft measuring drum 28 via clutch members 14, 15 and a drive belt 27. The B pin 29 and the A pin 30 move in and out of the circumferential surface of the weft length measuring drum 28 in synchronization with the rotation of the crankshaft, and measure the unwound weft from the weft cheese 32 via the tensor onto the weft length measuring drum 28. Controls winding and drawing to the main air jet nozzle 49.

Clutch member 14 is integrally connected to a drive shaft 19 connected to a crankshaft. On the other hand, the clutch member 15 is spline-coupled to the driven shaft 20. Further, the sleeve 16 is installed on the driven shaft 20 so that it can rotate relative to it and move in the axial direction. Therefore, the clutch member 15 moves integrally with the sleeve 16 in the axial direction, but is rotatable relative to the sleeve 16.
Note that, as shown in the figure, the clutch members 14 and 15 have engaging protrusions and recesses formed at positions eccentric from the axes of the drive shaft 19 and the driven shaft 20, so that the clutch members are engaged only when the phases of the protrusions and recesses match. 14 and 15 are engaged.

Boss 17 and sleeve 16 fixed to driven shaft 20
A compression spring 18 is installed between the left end of the
The clutch member 15 is always urged in the right direction, that is, toward the clutch member 14 side. A gear 34 is integrally attached to the end of the driven shaft 20. gear 34
is engaged with a gear 35, which is connected via an electromagnetic clutch 33 to the output shaft of an auxiliary motor 36.

A lever 21 is swingably supported by a pin 22 provided on the machine base, and its tip is engaged with the sleeve 16. The other end of the lever 22 is connected to a piston rod of an air cylinder 23 by a pin 24.

Then, operate the switching valve and open the air cylinder 2.
When the piston rod 3 is extended, the lever 21 rotates counterclockwise to disengage the clutch members 14 and 15 against the spring force of the compression spring 18.
When the electromagnetic clutch 33 is connected in this state, the rotation of the auxiliary motor 36 is transmitted to the winding arm 28a of the weft length measuring drum 28 via the gears 34, 35 and the drive belt 27. On the other hand, when the piston rod of the air cylinder 23 is moved backward, the spring force of the compression spring 18 causes the clutch member 1 to close.
4 and 15 are engaged, and the rotation of the main motor is transmitted via the drive belt 27 to the winding arm 28a of the weft length measuring drum.

Note that the limit switch 26 is actuated by the lever 21 and detects engagement of the clutch members 14 and 15.

Reference numeral 71 is a yarn guide, and 72 is a gripper, which is opened and closed by a cam 11 that rotates in time with the crankshaft, a lever 12 that swings around a fulcrum 13, and a cam follower 1 supported by the lever 12. . The filler 73 detects that the weft yarn is being supplied to the main air jet nozzle 49.

The main air jet nozzle 49 injects compressed air in synchronization with the movement of the crankshaft, and inserts the weft yarn into a shed formed between the warp yarns. Feeler 51,
52 detects insertion of the weft yarn, and reed 25 beats the inserted weft yarn.

Furthermore, an ejector type suction nozzle 61 is provided as a suction member between the main air jet nozzle 49 and the selvage thread. A shutter 63 is rotatably supported, and a suitable reciprocating member 62 such as an air cylinder or an electromagnetic solenoid is connected to the rotation shaft of the shutter 63. Reciprocating member 6
2, the shutter 63 can be moved between a position outside the weft path ejected from the main air jet nozzle 49 and a position on the weft path.

The air blow nozzle 64 faces the suction nozzle 61 across the weft insertion path, and injects an air stream toward the suction nozzle 61 to blow the weft interrupted by the shutter 63 into the suction nozzle 61. Make it absorb.

The action will be explained below.

<During steady operation> The crankshaft is driven by the main motor to cause the heald frame to move in an opening motion, and the weft is inserted into the shed formed between the upper and lower warps.

That is, in FIG. 1, the weft yarn unwound from the weft cheese 32 through the tensor is transferred from the crankshaft to the clutch members 14, 15 and the drive belt 2.
After being wound around the weft length measuring drum 28 and measured by the winding arm 28a of the rotating weft length measuring drum 28 via the gripper 72, it reaches the main air jet nozzle 49.

Gripper 72 and main jet nozzle 49
The operation is controlled in synchronization with the rotation of the crankshaft, and compressed air injected from the main jet nozzle 49 moves the weft stored on the weft measuring drum 28 into a shed formed between the upper and lower warps. Insert the weft into the

Next, an embodiment of the weft supply preparation method at the time of abnormal stop of the present invention will be described.

<When weft insertion error> (Refer to the second row from the right in Figure 2) The detectors 51 and 52 installed near the selvage threads on the opposite side of the main air jet nozzle 49 detect when the warp threads are almost closed (when the crank The weft insertion condition is checked at the angle α = 250 to 300 degrees), and the weft yarn inserted into the shed for some reason is transferred to the main air jet nozzle 4.
If a weft insertion error occurs in which the weft yarn does not reach the selvage yarn on the opposite side of the weft thread 9, the detectors 51 and 52 issue a weft insertion error signal (crank angle α ₀ in FIG. 3).

The main motor stop signal based on this weft insertion error signal stops the operation of the motor driving the machine base, and enters inertial operation (crank angle α ₁ in FIG. 3).

Furthermore, when a weft insertion error signal is transmitted, the piston of the reciprocating member 62 moves forward to cause the shutter 63 to cross the weft path, and the air blow nozzle 64
Inject compressed air from. In this way, the weft yarn ejected from the main air jet nozzle 49 after a weft insertion error is intercepted by the shutter 63, guided by the air jetted from the air blow nozzle 64, and reaches the suction nozzle 61. is attracted to.

After the machine, which was operating inertia, moved for about a cycle,
The warp is almost closed (crank angle α ₂ = approx.
300 degrees) and a machine stop signal is sent.

When the machine stops, the operator turns on the reverse button. This causes the air cylinder 23 to operate,
The clutch members 14 and 15 are disengaged so that the rotation of the crankshaft is not transmitted to the winding arm 28a of the measuring drum, while the electromagnetic clutch 33 is connected. In this state, the machine base is reversed (crank angle α ₃ in Figure 3). When the machine starts to reverse, the air cylinder 23 is turned off and the spring 1
8 presses the clutch member 15 toward the clutch member 14, but since the two clutch members 14 and 15 are out of phase, they do not engage, and the rotation of the crankshaft is caused by the winding arm 28 of the length measuring drum 28.
It is not communicated to a.

In order to remove the misplaced weft threads inserted into the shed, the machine is reversed more than once (approximately 480 degrees at crank angle), the warp threads are opened, and the main nozzle is installed above the sled, which is ideal for removing the weft threads. After the machine is reversed (from 300 degrees to 180 degrees in crank angle) to the crank angle at which 49 is closest to the suction nozzle 61 (crank angle α ₄ =approximately 180 degrees), the machine is stopped.

Next, the worker inspects the machine, and first,
It is checked whether the weft thread is connected from the weft thread cheese 32 to the suction nozzle 61 (if the weft thread is not connected, the next processing is performed as a supply error).

The worker removes the weft yarn that was inserted incorrectly, turns on the confirmation button installed to prevent fools, and then turns on the start button (crank angle α ₅ in Fig. 3), which starts the auxiliary motor. 36 drives the driven shaft 20 and the winding arm 28a of the weft length measuring drum 28 in the forward direction.
When the phases of the clutch members 14, 15 match, the compression spring 18 presses the clutch members 14, 15 to engage each other, and the rotation of the auxiliary motor 36 is stopped (crank angle α ₆ in FIG. 3). Therefore,
During this time, the winding arm 28a of the weft length measuring drum (crank angle when stopped = approximately 300 degrees)
The machine is rotated forward to an angle corresponding to the crank angle (approximately 180 degrees) of the reversed machine (the forward rotation angle is 240 degrees), and as the winding arm 28a rotates, the weft length measuring drum 28 is rotated as shown in FIG. The A pin 30 is retracted and one pit worth of weft on the length measuring drum 28 is removed, and the weft is removed by suction by the suction nozzle 61.

Next, the weft in front of the main nozzle 49 is cut by a cutter provided near the suction nozzle 61, and then the air cylinder 23 is activated.
The clutch members 14 and 15 are disengaged so that the rotation of the crankshaft is not transmitted to the winding arm 28a of the length measuring drum, while the electromagnetic clutch 33 is connected, and in this state the machine base is moved for alignment. is reversed (crank angle α ₇ in Figure 3). When the machine starts to rotate in reverse, the air cylinder 23 is turned off and the clutch member 15 is pressed toward the clutch member 14 by the spring 18, but since the phases of both clutch members 14 and 15 are shifted, they do not engage, and the crank The rotation of the shaft is not transmitted to the winding arm 28a of the weft length measuring drum 28. The machine rotates in reverse to the restart position (crank angle α ₈ = approximately 300 degrees) and stops.

Next, the winding arm 2 of the driven shaft 20 and the weft length measuring drum 28 is moved by the auxiliary motor 36.
Drive 8a in the forward direction (crank angle 180 degrees →
120 degrees of 300 degrees). When the phases of the clutch members 14 and 15 match, both the clutch members 14 and 15 are engaged and the rotation of the auxiliary motor 36 is stopped. During this time, the winding arm 28a of the weft length measuring drum 28
is rotated forward by an angle corresponding to the amount of reverse rotation of the machine (α ₉ in Fig. 4), and as shown in Fig. 4, the A pin 30 of the weft measuring drum 28 protrudes and the B pin 29 retracts. Therefore, the weft for one pick is stored on the length measuring drum 28.

In this state, the machine will resume operation.

<In the case of weft supply error> (See the right end of Fig. 2) One of the causes of the weft insertion error as described above is that the weft yarn feed from the weft cheese 32 to the main air jet nozzle 49
During this period, the weft yarn may be cut and the weft yarn may not be supplied to the main air jet nozzle 49 (a so-called supply error).

In this case, the weft yarn is not properly connected from the weft cheese 32 to the suction nozzle 61 when the machine is stopped. In such a case, after stopping the above-mentioned reverse rotation of the machine, between the process of removing the weft thread that was incorrectly inserted and the process of turning on the confirmation button (between crank angles α ₄ and α ₅ in Figure 3), ), weft length measuring drum 28
The weft thread is threaded through the thread so that the weft thread is normally connected from the weft thread cheese 32 to the suction nozzle 61.

That is, the weft is pulled out from the weft cheese 32, passed through the main air jet nozzle 49 from the circumferential surface of the weft length measuring drum 28, and the tip of the weft is sucked into the suction nozzle 61. Note that instead of being sucked into the suction nozzle 61, it may be hooked onto the temple of the loom, for example.

In this way, guide the weft yarn from the weft yarn cheese 32 to the suction nozzle 61, press the start button, and then follow the steps described above to start the auxiliary motor 36.
The driven shaft 20 and the winding arm 28a of the measuring drum are driven in the forward direction, rotated forward to an angle corresponding to the crank angle (180 degrees) of the reversed machine base (the forward rotation angle is 240 degrees), and the measuring drum is long drum 2
One pick worth of weft yarn on the weft 8 is removed and removed by suction by the suction nozzle 61, and the clutch member 1
4 and 15 are engaged with each other when their phases match, and the rotation of the auxiliary motor 36 is stopped.

Next, the cutter cuts the weft yarn in front of the main nozzle 49, and then the clutch member 14,
15 is disengaged, the machine rotates in reverse to the restart position (crank angle 300 degrees) and stops for alignment.

Furthermore, the auxiliary motor 36 drives the driven shaft 20 and the winding arm 28a of the length measuring drum in the positive direction again, and the A pin 30 of the length measuring drum 28 is driven.
Then, the B pin 29 emerges and retracts (see FIG. 6), and one pick's worth of weft yarn (approximately three and a half turns of weft yarn) is stored on the length measuring drum 28.

In this state, the machine will resume operation.

<When warp threads or selvage threads break> (Refer to the second row from the left in Figure 2) If the warp threads or selvage threads break, tie the cut warp threads or selvage threads together after the machine has stopped. Turn on the confirmation button and then turn on the start button. At the time of warp thread breakage or selvage thread breakage, there is no mis-inserted weft thread, so there is no need to remove the mis-inserted weft thread. From the crank angle when stopped (α ₂ = approx. 300 degrees), the specified crank angle (α ₄ = approx. 180
(300 degrees → 180 degrees).
120 degrees).

Below, follow the same procedure as when turning on the start button when weft insertion was incorrect, as described above, and turn on the auxiliary motor 3.
6, the driven shaft 20 and the winding arm 28a of the weft length measuring drum 28 are driven in the forward direction, and are rotated in the forward direction to an angle corresponding to the crank angle (approximately 180 degrees) of the reversed machine base (the crank angle to be rotated in the forward direction). (approximately 240 degrees), the weft for one pick on the length measuring drum 28 is removed by suction by the suction nozzle 61, and the clutch members 14 and 15 engage with each other when the phases match, and the auxiliary motor 36 Rotation stops.

Next, the cutter cuts the weft yarn in front of the main nozzle 49, and then the clutch member 14,
15 is disengaged, the machine rotates in reverse to the restart position (crank angle of approximately 300 degrees) and stops for alignment.

Next, the winding arm 2 of the driven shaft 20 and the weft length measuring drum 28 is moved by the auxiliary motor 36.
8a in the forward direction again, the A pin 30 and B pin 29 of the length measuring drum 28 come out and go down, and one pick's worth of weft (approximately three and a half turns of weft) is stored on the weft length measuring drum 28. do.

In this state, the machine will resume operation.

<When operating the stop button> (See the left end of Figure 2) In this case, the process is the same as the process when the warp thread breaks or the selvage thread breaks as described above, except that the warp thread or selvage thread tying process is not necessary. .

In the above explanation, the weft yarn for at least one pick stored in the weft length measuring drum is removed by a suction member (suction nozzle) installed on the outlet side of the main air jet nozzle between the machine stop and restart. 61), however, in carrying out the present invention, the weft yarn is not limited to suction using a suction member, and may be removed by other appropriate taking-off means such as a winding tool.

Furthermore, even after detecting a misplaced yarn, the weft yarn next to the misplaced yarn is gripped with a gripper or the like on the upstream side of the main air jet nozzle to prevent weft insertion by preventing it from being sprayed from the main air jet nozzle. The method of the invention is applicable.

Further, the operation based on the cause of the stop shown in FIG. 2 is standard, and various applications are possible. As an example, repairing scratches, etc. (for example, after weaving several picks for some reason even though the warp threads were broken,
When a worker performs a manual operation (when stopping), it is not easy to match the starting crank angle to the correct starting crank angle because it is manual operation, but according to the present invention, the starting crank angle is adjusted to the approximate starting crank angle position. If you do, you can start it.

[Effects of the Invention] According to the present invention, regardless of the relationship between the crank angle after reversing the loom and the crank angle when the loom is stopped, that is, the crank angle after reversing the loom is equal to the crank angle when the loom is stopped. Regardless of whether the angle is behind or ahead, the drum is rotated by at least one rotation of the machine, and the weft yarn of one pick stored in the drum before rotation is rotated in the same way. Correspondingly, there is no need to delicately control the stop position of the loom as in the prior art, and a complicated and expensive device for controlling the stop position can be eliminated.

Moreover, according to the present invention, weft feeding errors, especially
If the weft yarn is wrapped around the weft length measuring drum, cut and remove the wrapped weft yarn, pass the weft yarn from the winding arm of the length measuring drum to the main nozzle via the gripper, and remove the suction means etc. at the main nozzle outlet. When the machine is guided to the machine and the start button is turned on, the length measuring drum rotates and one pick's worth of weft is stored on the length measuring drum.Even if there is a weft supply error, it can be handled with the same operation as when there is a weft insertion error. This eliminates the need to press the drum rotation button to wrap one pick of weft yarn around the drum, eliminating operator errors, allowing for weaving of high-quality fabrics, and shortening the abnormal processing time in the event of an abnormal stop. be able to.

Therefore, according to the present invention, it is possible to almost automatically wind the weft yarn around the weft length measuring drum, thereby reducing the labor burden on the worker and increasing labor productivity. Malfunctions can be prevented.

[Brief explanation of the drawing]

Fig. 1 is a plan view showing an outline of the drive system of the air jet loom according to this embodiment, Fig. 2 is a flowchart of an embodiment of the present invention, and Fig. 3 is a process for weft insertion errors according to the present invention. 4 is a plan view showing the procedure for storing the weft yarn on the weft length measuring drum in FIG. FIG. 7 is a plan view showing the procedure for storing weft yarns on the length measuring drum, and is a processing operation diagram when warp yarns or selvedge yarns break according to the present invention. 14, 15...Clutch member, 28...Weft length measuring drum, 49...Main air jet nozzle,
51, 52...detector, 61...suction nozzle, 62...reciprocating member, 63...shutter,
64...Air blow nozzle.

Claims (1)

[Scope of Claims] 1. At least one pick's worth of weft is wound and stored on the storage surface of a weft measuring drum by a driving force from the crankshaft of the loom, and during machine operation, the one pick's worth of weft is Weft insertion is performed by measuring the length using a weft locking pin that can be brought into and out of contact with the storage surface, and when a stop signal from the main motor is generated, inertial operation is performed while constantly preventing the next weft insertion, and the machine is stopped. After the machine is stopped, the drive system for the weft length measuring drum is disconnected from the crankshaft, and the crankshaft rotates the loom in reverse, and the auxiliary motor drives the drive system for the weft length measuring drum to measure a predetermined amount of weft. In the weft supply preparation method in which the weft yarn is stored on the weft length measuring drum, between the time when the machine is stopped and the machine is restarted, the auxiliary motor rotates the drive system of the weft length measuring drum in the normal direction and the weft yarn is stored on the weft length measuring drum. 1. A weft supply preparation method comprising: removing at least one pick of weft yarns, and then restarting the loom by connecting the crankshaft and the weft measuring drum in phase. 2. The weft supply preparation method according to claim 1, wherein at least one pick's worth of weft stored in the weft length measuring drum is removed in the weft insertion direction. 3. The weft supply preparation method according to claim 2, wherein at least one pick of weft stored in the weft length measuring drum is removed by suction by a suction member provided at the outlet of the weft insertion main nozzle. 4. Any one of claims 1 to 3, which rotates the drive system of the weft length measuring drum in the normal direction to a crank angle corresponding to the reverse crank angle of the machine base between stopping and restarting the machine base. The weft supply preparation method according to item 1. 5. The engaging portion of the clutch member provided between the drive system of the weft length measuring drum and the crankshaft of the loom is eccentric from the rotation axis, and when the drive system of the weft length measuring drum rotates forward, the weft length measuring drum The weft supply preparation method according to claim 4, wherein the drive system of the long drum and the crankshaft of the loom engage only in a predetermined phase.