GB1571733A - Loom including a weft monitoring device - Google Patents

Description

(54) A LOOM INCLUDING A WEFT MONITORING DEVICE FOR LOOMS (71) We, AKTIENGESELLSCHAFT ADOLPH SAURER, a Swiss Company, of 9320 Arbon, Switzerland, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement : - This invention relates to looms and more particularly to the incorporation of a weft monitoring device therein. The purpose of the device is to monitor the insertion of the weft across the shed of the loom by means of a scanning light monitor located outside of the loom shed.

Weft monitoring devices of the foregoing type which are installed outside of the loom shed at the edge thereof where the thread emerges are known. The devices aid in signalling the brief passage of the weft past the light sensing monitor during the beating stage through the loom such as described in British Patent Specification No. 960,593.

When weft malfunctions occur, i.e., when the passage of thread is not sensed by the light sensing monitor, an audio signal is activated, and the power loom may also be shut down.

Such devices may, in addition, measure the period of time required for the weft to emerge from the light sensing monitor, so that when a pre-set time limit is exceeded, an audio signal is activated, and the power loom may again be shut down. Such a device is disclosed in British Patent Specification No.

1,416,814.

The weft monitoring devices described above share the common disadvantage of not detecting a weft malfunction until one weft insertion cycle has been completed. Very little time is left to shut down the loom. Rapid shut down would require powerful braking devices, which would place heavy stress on the major components of the power loom. Furthermore, with the former monitoring device, if a broken weft is drawn by the weft inserter, it could damage a correct previous insert.

Although such a mishap is less likely to occur with the latter monitoring device, it is neverthe less, a possibility. Owing to its chronometric and integrating components, the electronic switching of the latter device may be more easily applied.

The aim of the present invention is to alleviate the disadvantages of known monitoring devices and provide a loom having a simplified monitoring device with a less complicated electronic switching system so that the weft insertion process may be monitored during its entire cycLe According to the invention, a loom includes a device for monitoring the progress of the weft thread into the shed region of the loom, which device comprises a pair of substantially parallel walls each formed with a slot on either side of a space across which a said weft thread is guided by the slots prior to entering the shed region; a light source and a light sensor located at either end of a light guide path which passes through said space, the path of a said weft thread across said space being defined by the base of the slots and located substantially centrally of the light guide path.

The light path of the device normally fills the entire width between the weft guides, which define a narrow slit extending in the direction of the inserted weft thread. Tensioners may be installed to define a clear path for the inserted weft thread.

The device described herein is particularly suited for monitoring the feeding of a looped weft having two legs as it is being fed. One leg of the loop is clamped adjacent the weft thread supply, i.e., by a restraining device that is installed on the weft supply side of the loom. The other leg of the loop is drawn away by the inserter through the monitoring device and across the loom shed, and the clamped leg of the insert loop is held by a tensioner on the monitoring device. In this way, a stationary weft may be held more easily by restraining tensioners on either side of the loom shed and become stabilized.

Figure 1 shows diagrammatically a loom inincluding a weft monitoring device according to the invention during the weft insertion process; Figure 2 shows the loom of Figure 1 during the beating of the inserted weft; Figure 3 illustrates schematically the weft monitoring device in Figure 1; and Figure 4 is a cross-sectional view along line IV-IV in Figure 3.

As shown, a fabric 1 is woven using the weft emanating from a supply 2 held by a dispenser (not shown) at the left in Figure 1.

A first thread clamp 3 engages the end of the weft that had been previously inserted. A second thread clamp 4 installed at the point on the edge of the fabric where the weft emerges performs the same function. A third thread clamp 5 is movable to hold the end of the thread supply 16 which has been separated by the cutters 8 from the thread after the weft has been beaten. By the edge of the fabric, at the weft insert side, a thin width guide 6 guides the weft. The weft is inserted through the guide and through the loom shed in the form of a loop having legs 9 and 10. A rapier 7, which has a hook or gripper 11, draws the weft loop from the supply 2 through the guide 6. Thereafter, the weft loop is inserted in the loom shed, which is formed by the underlying warp sheet 12 and the overlying warp sheet 13.The rapier 7 is equipped with a rack gear (not shown) on which teeth 21 of a pinion gear wheel 19 engage. Wheel 19 is rotatable clockwise and counter-clockwise, as indicated by a double arrow 20, thus producing an alternating backward and forward motion of rapier 7. Once the weft has been inserted through the loom shed, the reed 14 moves through the shed and beats the weft as shown in Figure 2. The end of the weft 16 that is the next to be engaged by the hook or gripper 11 is then clamped by the thread clamp 5.

The guide 6 is formed by a projection created by the extension of side frame 17 of a light sensing monitor device carrier. Side frame 17 includes a deep groove formed by side edges 24, 25 which create and define a guide slot of the light guide path 28. The other side frame 18 of the guide 6 also includes a deep groove formed by similar side edges 24', 25'. The two grooves 24, 25 and 24', 25' define the top and bottom edges of a bridge that will be created by weft 9 between the side frames. The weft 9 is held taut across this bridge during the insertion process.

There is a light sensing monitor device which includes a light emitting diode 22 and a photoelectric cell 23 that is arranged to sense the light from diode 22. There is a light carrier conduit 30 that extends between the diode 22 and the cell 23 and its path crosses that of the weft thread through the slot defined by the guide 6. The cross-section of the light carrier conduit is made elongate where the weft passes through the guide 6, the longer dimension of the cross-section extending along a line joining the basis of the slots. The short dimesion may be about the thickness of the weft itself so that as the weft passes through the guide 6, it inteferes with the light path. The light carrier conduit 30 at the weft monitoring location has a width substantially equal to the spacing of the edges 24 and 25 of the guide 6, or the space between side frames 17 and 18.Although the drawings show the stationary leg 9 of the insert loop in guide path 28, i.e., lying in the path of the scanning beam the device is also suitable for monitoring single drawn threads.

It is apparent that the weft will be drawn through the guide 6 and thereafter across the loom shed at predetermined time intervals. If a weft thread does not block the light in the guide path 28 after any determined interval, this indicates the occurrence of a malfunction or shows that the weft thread has broken.

When the photocell 23 senses this incomplete blockage of the light, it will immediately sense that the malfunction occurred.

When the cell 23 senses weft insertion malfunction, for example, due to incorrect timing of weft insertion or to weft breakage during the normal weaving process, it activates the alarm 31 in a conventional electronic circuit.

WHAT WE CLAIM IS: 1. A loom including a device for monitoring the progress of the weft thread into the shed region of the loom, which device comprises a pair of substantially parallel walls each formed with a slot on either side of a space across which a said weft thread is guided by the slots prior to entering the shed region; a light source and a light sensor located at either end of a light guide path which passes through said space, the path of a said weft thread across said space being defined by the base of the slots and located substantially centrally of the light guide path.

2. A loom according to Claim 1 wherein the cross-section of the light guide path is oblong where it traverses said space, the longer dimension of the cross-section extending along a line joining the basis of the slots.

3. A loom according to any preceding Claim including an alarm device connected to the light sensor for activation in response to variation of the passage of weft thread across said space.

4. A loom according to any preceding Claim including means for withdrawing the weft thread from a supply in the form of a two legged loop; and a clamping device near the thread supply for clamping one leg of a said loop.

5. A loom substantially as described herein and illustrated in the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (5)

**WARNING** start of CLMS field may overlap end of DESC **. to the invention during the weft insertion process; Figure 2 shows the loom of Figure 1 during the beating of the inserted weft; Figure 3 illustrates schematically the weft monitoring device in Figure 1; and Figure 4 is a cross-sectional view along line IV-IV in Figure 3. As shown, a fabric 1 is woven using the weft emanating from a supply 2 held by a dispenser (not shown) at the left in Figure 1. A first thread clamp 3 engages the end of the weft that had been previously inserted. A second thread clamp 4 installed at the point on the edge of the fabric where the weft emerges performs the same function. A third thread clamp 5 is movable to hold the end of the thread supply 16 which has been separated by the cutters 8 from the thread after the weft has been beaten. By the edge of the fabric, at the weft insert side, a thin width guide 6 guides the weft. The weft is inserted through the guide and through the loom shed in the form of a loop having legs 9 and 10. A rapier 7, which has a hook or gripper 11, draws the weft loop from the supply 2 through the guide 6. Thereafter, the weft loop is inserted in the loom shed, which is formed by the underlying warp sheet 12 and the overlying warp sheet 13.The rapier 7 is equipped with a rack gear (not shown) on which teeth 21 of a pinion gear wheel 19 engage. Wheel 19 is rotatable clockwise and counter-clockwise, as indicated by a double arrow 20, thus producing an alternating backward and forward motion of rapier 7. Once the weft has been inserted through the loom shed, the reed 14 moves through the shed and beats the weft as shown in Figure 2. The end of the weft 16 that is the next to be engaged by the hook or gripper 11 is then clamped by the thread clamp 5. The guide 6 is formed by a projection created by the extension of side frame 17 of a light sensing monitor device carrier. Side frame 17 includes a deep groove formed by side edges 24, 25 which create and define a guide slot of the light guide path 28. The other side frame 18 of the guide 6 also includes a deep groove formed by similar side edges 24', 25'. The two grooves 24, 25 and 24', 25' define the top and bottom edges of a bridge that will be created by weft 9 between the side frames. The weft 9 is held taut across this bridge during the insertion process. There is a light sensing monitor device which includes a light emitting diode 22 and a photoelectric cell 23 that is arranged to sense the light from diode 22. There is a light carrier conduit 30 that extends between the diode 22 and the cell 23 and its path crosses that of the weft thread through the slot defined by the guide 6. The cross-section of the light carrier conduit is made elongate where the weft passes through the guide 6, the longer dimension of the cross-section extending along a line joining the basis of the slots. The short dimesion may be about the thickness of the weft itself so that as the weft passes through the guide 6, it inteferes with the light path. The light carrier conduit 30 at the weft monitoring location has a width substantially equal to the spacing of the edges 24 and 25 of the guide 6, or the space between side frames 17 and 18.Although the drawings show the stationary leg 9 of the insert loop in guide path 28, i.e., lying in the path of the scanning beam the device is also suitable for monitoring single drawn threads. It is apparent that the weft will be drawn through the guide 6 and thereafter across the loom shed at predetermined time intervals. If a weft thread does not block the light in the guide path 28 after any determined interval, this indicates the occurrence of a malfunction or shows that the weft thread has broken. When the photocell 23 senses this incomplete blockage of the light, it will immediately sense that the malfunction occurred. When the cell 23 senses weft insertion malfunction, for example, due to incorrect timing of weft insertion or to weft breakage during the normal weaving process, it activates the alarm 31 in a conventional electronic circuit. WHAT WE CLAIM IS:

1. A loom including a device for monitoring the progress of the weft thread into the shed region of the loom, which device comprises a pair of substantially parallel walls each formed with a slot on either side of a space across which a said weft thread is guided by the slots prior to entering the shed region; a light source and a light sensor located at either end of a light guide path which passes through said space, the path of a said weft thread across said space being defined by the base of the slots and located substantially centrally of the light guide path.

2. A loom according to Claim 1 wherein the cross-section of the light guide path is oblong where it traverses said space, the longer dimension of the cross-section extending along a line joining the basis of the slots.

3. A loom according to any preceding Claim including an alarm device connected to the light sensor for activation in response to variation of the passage of weft thread across said space.

4. A loom according to any preceding Claim including means for withdrawing the weft thread from a supply in the form of a two legged loop; and a clamping device near the thread supply for clamping one leg of a said loop.

5. A loom substantially as described herein and illustrated in the accompanying drawings.