Selvage insertion apparatus for a weaving machine

A selvage insertion apparatus (13) for a weaving machine with at least one insertion arm (18) and at least one filling thread clamp (17) which can be applied through a drive device to control a filling thread and which operate from a common drive shaft (40). An individual drive motor (61) is operated by a programmable control system (14) and powers the drive shaft (40).

BACKGROUND OF THE INVENTION
 1. Field of the Invention
 The invention relates to selvage insertion apparatus for a weaving machine,
 with at least one insertion arm and at least one thread clamp which have a
 drive device to control a weft thread and which operate from a common
 drive shaft.
 2. Description of the Related Art
 With regard to known selvage insertion apparatus of the above-mentioned
 type U.S. Pat. Nos. 4,905,740; 4,909,283 and 4,957,145; European patent A
 0,626,476), the power for the drive shaft is taken from a weaving
 machine's main shaft. Accordingly the selvage insertion apparatus operates
 synchronously with the weaving machine's main shaft and runs according to
 this main shaft's speed.
 Furthermore U.S. Pat. No. 5,158,119 discloses selvage insertion apparatus
 including an insertion arm, a thread clamp and a thread cutter each with
 its own drive motor. The insertion arm is axially displaceable by one
 motor and rotatable by another motor. The thread clamp and the thread
 scissors each are axially displaceable by their own motors. This selvage
 insertion apparatus is operated by a microprocessor that controls the
 individual motors. This microprocessor also receives data concerning the
 weaving machine's weaving cycle. Position sensors are combined with the
 insertion arm and immediately detect operational malfunction, whereupon
 the microprocessor shuts down the motors to prevent collision between the
 insertion arm and/or the thread clamp and the scissors and the reed.
 SUMMARY OF THE INVENTION
 The objective of the invention is to provide a selvage insertion apparatus
 of the above type that improves selvage formation.
 This problem is solved by providing a particular drive motor for the drive
 shaft and providing this motor with a programmable control system.
 The invention is based on the recognition that the weaving machine's main
 shaft does not rotate at constant speed. This is because the main shaft
 reciprocally drives weaving machine components such as a batten and
 shed-formers. Furthermore, the varying speed of the main shaft also
 depends on the pattern of the warp threads according to which the shed
 formers are raised and lowered to form consecutive sheds from a specific
 number of warp threads that are moved up and down. In accordance with the
 invention, the drive motor of the selvage insertion apparatus is operated
 by its own programmable control system, and therefore its position and in
 particular, the speed of its insertion arm, can be selected in such manner
 that the ends of the filling treads can all be inserted in an identical
 manner. This feature is made possible because the insertion arm is moved
 into and out of the warp threads always at a predetermined time and with
 predetermined speed, and consequently, the ends of the filling threads are
 always accurately laid into a subsequent shed, thereby improving the
 fabric quality. This is possible because the predetermined speed of the
 insertion arm is independent of the speed fluctuations of the weaving
 machine's main shaft.
 In one embodiment of the invention, the control system includes a device
 that controls the speed of the selvage insertion device drive motor during
 the insertion of the ends of filling threads according to the control
 programs of the control system. As a consequence, the selvage insertion
 arm may remain (dwell) as long as needed between the warp threads which is
 advantageous for good selvaging.
 In another embodiment of the invention, retrievable programs to run the
 drive motors are stored in the control system and are designed for
 different kinds of filling threads and/or weave patterns. Consequently,
 the operation of the drive motor and hence in particular the position and
 the speed of the insertion arm are easily adapted to the particular
 filling threads that are processed and/or to the particular weave
 pattern(s) used.
 In yet another embodiment of the invention, the control system contains a
 device for comparing reed motion with the motions of the insertion arm and
 the thread clamp, and changes the drive-motoroperation to avoid collisions
 between the devices. In this manner, malfunctions or defective adjustments
 can be avoided that might otherwise cause the reed to hit the insertion
 arm or the thread clamp with ensuing damage to the reed elements.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION
 The portion of a weaving machine shown in FIG. 1 includes two side frames 1
 and 2 spanned by a crossbar 3; a batten 4 with a reed 5; a drive motor 6,
 connected by a transmission 7 including two belt pulleys and one belt
 connected to a drive 9 for the weaving machine's main shaft 8 operating
 the batten 4; a filling thread cutter 10; several selvage insertion
 devices 11, 12, 13; and a control system 14. The filling thread cutter 10
 comprises filling thread scissors 15 provided with scissor blades and a
 drive unit 16. Selvage insertion apparatus 11 includes a thread clamp 17
 and an insertion arm 18. Selvage insertion apparatus 12 contains two
 thread clamps 17, two insertion arms 18 and filling thread scissors 19
 with scissor blades mounted between the two thread clamps 17. Selvage
 insertion apparatus 13 contains one thread clamp 17, one insertion arm 18
 and filling thread scissors 19 provided with scissor blades.
 An encoding disk 20 is mounted on the weaving machine's main shaft 8 and a
 sensor 21 transmits signals of the angular position of the encoding disk
 20 and hence, the position of the main shaft 8 to the control system 14.
 FIG. 1 also shows two fabrics 22 and 23 with their selvages 24 and 25 and
 warp threads 26. An expander 27 with a proximity sensor 28 is associated
 with the selvages of fabrics 22, 23 facing the side frames 1 or 2. The
 proximity sensors 28 respond to the position of reed 5 and generate a
 corresponding signal. This embodiment shows an airjet weaving machine
 provided with two main jet nozzles 29 mounted on the batten 4. The cutter
 10, the selvage insertion apparatus 11, 12,13 and the expanders 27 are
 mounted on the crossbar 3.
 FIG. 2 shows the selvage insertion apparatus 13. The insertion arm 18 is
 provided with a clamp 30 affixed by a screw 32 on its drive bar 31. The
 insertion arm 18 is displaceable by the drive bar 31 in the axial
 direction of this rod and can be rotated in the direction R when the drive
 bar 31 is rotated. The thread clamp 17 is displaceable by a drive bar 33
 in the axial direction of this bar. The thread clamp 17 furthermore is
 provided with a pushbar 34 so that it can open the clamp, this pushbar 34,
 in turn, being activated by a catch 35 of the clamp 30. The filling thread
 scissors 19 are mounted on a drive bar 36 and the two can be displaced in
 the bar's axial direction and, when moving toward the reed 5, this motion
 is converted by device 37 (indicated only in schematic manner) into a
 cutting motion of the blades of the filling thread scissors 19. The device
 opening the filling thread clamp 17 and actuating the filling thread
 scissors 19 are well known in the art and therefore are not discussed
 further herein. The selvage insertion apparatus 13 is affixed by a spacer
 38 to the crossbar 3.
 The drive bars 31, 33, 36 each are guided in a sliding bearing (not shown)
 mounted in the front part 39 of the housing of the selvage insertion
 apparatus 13 in such manner that they all can be axially displaced. The
 drive bars 33 and 36 are provided with axial bevels the shape of which is
 assumed by the sliding bearings. This feature prevents the drive bars 33,
 36 from rotating. The sliding bearing for the drive bar 31 includes a
 cylindrical inner contour to allow rotation of the drive bar 31.
 As shown by FIG. 3, the selvage insertion apparatus 13 includes a common
 drive shaft 40 to power the drive bar 33 of the thread clamp 17, the drive
 bar 31 of the insertion arm 18 and the drive bar 36 of the filling thread
 scissors 19. The drive shaft 40 drives cam disks 41, 42 mounted fixedly in
 axially spaced relationship on this shaft 40 and provided with cam forms
 43, 44 and 45, 46. The selvage insertion apparatus 13 further comprises a
 pivot device 47 on which are pivotably mounted three levers 48. Each lever
 48 is provided with a stud 49 and a forked end 50. The stud 49 of the
 first lever 48 is guided on cam form 43. The forked end 50 of this first
 lever 48 engages between two radial shoulders 36A of the drive bar 36. The
 lever 48 is rotated about the pivot 47 by a rotation of the drive shaft 40
 and through the stud 49, and as a result the drive bar 36 is axially
 displaced by the forked end 50 engaged between the shoulders 36A. The
 drive bars 31 and 33 are similarly axially displaced by the drive shaft 40
 and by the levers 48 each provided with a stud 49 and a forked end 50. The
 drive bar 31 includes two radial shoulders 31A and the drive bar 33, and
 two shoulders 33A that are engaged in each case between forked ends 50 of
 the respective levers 48.
 The drive bar 31 includes a lever 51 affixed in the axial direction of the
 drive bar 31 by a support 52. The drive bar 31 can be axially displaced
 within the lever 51, however it is affixed in the circumferential
 direction. Another lever 53 is mounted inside the selvage insertion
 apparatus 13 and is rotatable about a shaft (not shown) and is provided
 with a stud 54 entering the cam form 46 of cam disk 42. As the drive shaft
 40 rotates, the lever 53 is reciprocated along the direction V. The lever
 53 and the lever 51 of the drive bar 31 are joined to each other by a
 connecting rod 55 and each by a swivel joint. Motion of the lever 53 in
 the direction V therefore will be converted into rotational motion for the
 drive bar 31 in the direction R (FIG. 2).
 Rotation of the drive shaft 40 entails, therefore, linear motions of the
 filling thread clamp 17, the insertion arm 18 and the filling thread
 scissors 19, with rotation furthermore being superposed on the insertion
 arm 18. The shapes and dimensions of the cam forms 43 through 46, of the
 levers 48, 51, 53 and of the connecting rod 55 are selected in such manner
 that they will implement the required motions. Because the motions of the
 filling thread clamp 17, the insertion arm 18 and the filling thread
 scissors 19 can be implemented by mechanical connections to the drive
 shaft 40, they are mutually and exactly synchronized and they will
 advantageously remain synchronized when the selvage insertion apparatus 13
 is operational. Operation of the filling thread clamp 17, the filling
 thread scissors 19 and the insertion arm 18 from one common drive shaft 40
 in turn powered by only one drive motor 61 offers the advantage that the
 internal synchronization of the filling thread clamp 17, filling thread
 scissors 19 and insertion arm 18 is unaffected by the control operation of
 the drive motor 61, and as a result the requirements for controlling the
 drive motor 61 are fewer than when all components are driven by their own
 drive motors and must be controlled accordingly.
 The drive shaft 40 of the selvage insertion apparatus 13 rests on bearings
 56, 57 in the housing 58. To axially affix the drive shaft 40, the bearing
 56 is positioned by a nut 59 screwed onto the drive shaft 40. The bearing
 56 in turn is positioned in the housing 58 by a fastener 60. The bearing
 57 illustratively is positioned by a press-fit in the housing 58.
 The selvage insertion apparatus 13 includes a drive motor 61 controlled by
 the control system 14. The motor shaft 62 rests in bearings 63 and 64. The
 bearing 63 in turn rests in the motor housing 65 and the bearing 64 is
 mounted in a partition 66. The motor housing 65 is affixed by screws 67 to
 the housing 58. The motor shaft 62 is linked by a flexible coupling 68 to
 the drive shaft 40. This flexible coupling 68 compensates against
 alignment deviations between the motor shaft 62 and the drive shaft 40
 while precluding relative circumferential motion. An encoding disk 69 is
 mounted on the drive shaft 40 and cooperates with a sensor 70 mounted
 inside the housing 65 that transmits signals which are a function of the
 angular position of the encoding disk 69, and hence of the drive shaft 40,
 to the control system 14. A rotor 71 of the electric motor is mounted on
 the motor shaft 62 and cooperates with a drive motor stator 72 inside the
 motor housing 65.
 In regard to embodiments that are modifications over that of FIG. 3, the
 motor shaft 62 of the drive motor 61 and the drive shaft 40 of the selvage
 insertion apparatus 13 are not configured in axial sequence. In this
 latter case they are connected by transmission elements. The motor shaft
 and the drive shaft 40 can be configured to run parallel to each other or
 illustratively also at an angle of 90.degree.. In the former case a gear
 or belt transmission may be used, whereas in the latter a bevel-gear
 transmission may be used.
 In the embodiment of FIG. 4, the drive motor 61 and the selvage insertion
 apparatus 13 are one sub-assembly with only one housing. The components
 corresponding to the embodiment of FIG. 3 are denoted by the same
 references and will not be discussed further hereafter. The rotor 71 is
 mounted on the drive shaft 40 which thereby becomes the motor shaft. The
 associated stator 72 is received in the housing 58 of the selvage
 insertion apparatus 13. This drive motor 61 also is controlled from the
 control system 14. To assure problem-free assembly, the bearings 56, 57
 for the drive shaft 40, which also is a motor shaft, are each mounted in a
 flange 73 affixed by screws 74 to the housing 58. The embodiment of FIG. 4
 offers the advantage compared to the embodiment of FIG. 3 that this
 sub-assembly is more compact and thus demands less space inside the
 weaving machine.
 Operation of the selvage insertion apparatus 13 will now be described. This
 description appropriately also applies to operating the selvage insertion
 devices 11, 12.
 The sensor 21 cooperating with the encoding disk 20 transmits signals which
 are a function of the angular position of the weaving machine's main shaft
 8 relative to the control system 14. This position also represents the
 position of the batten 4 and of the positions of the shed-forming devices
 (not further discussed herein) and hence of the sheds formed by the warp
 threads 26. The position of the drive shaft 40 of the selvage insertion
 apparatus 13 is determined by the control system 14 from the signals
 derived from the sensor 70 which senses the rotation of the encoding disk
 69 and transmits the information to the control system 14.
 The control system 14 controls the speed-controlled drive motor 61 of the
 selvage insertion apparatus 13. Speed control can be implemented in a
 known manner using frequency control or phase-angle control. The signals
 from the sensor 70 may be used in this process for feedback by the control
 system 14.
 The invention not only synchronizes the speed of the drive motor 61 with
 that of the weaving machine's main shaft 8, but furthermore the speed of
 the drive motor 61 is controlled in a desired manner when the filling
 threads are inserted. FIG. 5 shows such operation. The curve 75 shows the
 observed speed of the weaving machine's main shaft 8. Curves 76, 77 and
 76A, 77A show the controlled speed of the drive shaft 40. The curves show
 two weaving cycles. The curves 76 and 76A depend on the selected type of
 inserted filling thread and/or weave pattern, that is, the pattern at
 which the inserted filling thread is interlaced between the warp threads
 26. As regards filling threads of low strength, the curves 76 and 76A are
 selected in such manner that the insertion arm 18 will not apply large or
 strongly changing forces to the filling thread. As regards weaves with
 only few warp threads 26 in the upper shed, the curves 76 and 76A
 illustratively are selected in such a way that the insertion arm 18 dwells
 longer between the sets of warp threads than for weaves with a large
 number of warp threads 26 in the upper shed.
 The initial position O coincides with the position at which the selvage
 insertion apparatus 13 or at least its insertion arm 18 as yet has not
 been applied to the weft. At this stage the weaving machine's main shaft 8
 is in a specifically defined reference position, for instance 100.degree.
 behind the stop position of the reed 5. The speed of the drive motor 61 is
 controlled in such manner that the speed of at least the insertion arm 18
 shall follow a prescribed function during filling thread insertion.
 For this purpose the speed of the drive motor 61 is controlled according to
 a predetermined function while taking into account the mechanical
 transmission between the drive shaft 40 and the drive bar 31. Such a
 function is shown in FIG. 5 by the curve 76. An appropriate function is
 stored in a memory in the control system 14 for every kind of insertable
 filling thread. From the initial position O, the speed of the drive motor
 61 is controlled by a program retrieved from the control system 14 and
 independently of the speed of the weaving machine's main shaft 8. A check
 is carried out using the signals from the sensor 70 whether the drive
 motor 61 is in fact being controlled according to the speed-function of
 the curve 76. Where required, correction is introduced to match the speed
 of drive motor 61 to this function. This speed control takes place at
 least over the time interval within which a filling thread is inserted by
 the insertion arm 18 into a subsequent shed, preferably over the full time
 interval during which the selvage insertion apparatus 13 acts on the
 filling thread. This control is applied between the initial position O and
 end position PE of the drive shaft 40 of the selvage insertion apparatus
 13, for instance 120 to 180.degree. later, at which time the selvage
 insertion apparatus 13 no longer acts on the filling thread. The function
 of the curve 76 may be selected in such manner that, by taking into
 account the mechanical transmission constraints, the speed of the
 insertion arm 18 shall be approximately constant or, if necessary,
 slightly higher. This procedure offers the advantage that the filling
 thread remains taut in the hook of the insertion arm 18 and the likelihood
 of the insertion arm 18 losing the filling thread will be reduced.
 Even after the time when the drive shaft 40 has reached the end position
 PE, the speed of the drive shaft 40 is still being controlled by the drive
 motor 61 as a function of the position and speed of the weaving machine's
 main shaft 8. This function is predetermined in such a way that the drive
 shaft 40 again shall be in the next initial position O when the main shaft
 8 is at the next reference position. The expected time at which the main
 shaft 8 will reach the reference position is determined by the control
 system 14 as a function of the signals from the sensor 21 and taking into
 account further effects, for instance the weave pattern stored in the
 control system 14 and implemented by the weaving machine. The speed of the
 drive motor 61 is controlled in such a way that the drive shaft 40 shall
 be in the initial position O at the predetermined time. In this process
 the speed of the drive motor 61 is controlled in such manner that the
 speed between the previous end position PE and the ensuing initial
 position O shall be approximately constant. The speed at the previous end
 position PE and the next initial position O is determined by the function
 stored in the control system 14. The function of the curve 77 must be
 continuous with those of the curves 76 and 76A.
 The irregularity of the speed of the main shaft 8 shown by the curve 75
 does not affect the speed function of the drive shaft 40 so long as the
 selvage insertion apparatus 13 cooperates with the filling thread. The
 drive shaft 40 is controlled by a predetermined speed function stored in
 the control system 14. The effect of the irregular speed of the weaving
 machine's main shaft 8 is cancelled by the control system 14 according to
 the curves 77, 77A by appropriately powering the drive motor 61 while the
 selvage insertion apparatus 13 is not cooperating with a filling thread.
 The speed thus provided does not affect selvage formation.
 If the speed of the drive motor 61 were to be wholly synchronized with the
 speed of the main shaft 8, then the speed of the selvage insertion
 apparatus 13 would vary when cooperating with the filling thread. The
 latter speed no longer would be optimal to insert a filling thread.
 Cancellation of speed changes between the previous end position and the
 next initial position O of the drive shaft 40 is easily implemented and
 raises no problems because it does not affect the action of the selvage
 insertion apparatus 13 on the filling thread.
 The selvage insertion apparatus 13 is independently controlled by the
 weaving machine's main shaft 8 when a filling thread is inserted and there
 is a chance that parts of the selvage insertion apparatus 13, for instance
 the filling thread clamp 17, the insertion arm 18 or the filling thread
 scissors 19 will make contact with the weaving machine's reed 5. Such
 contact might materialize if the synchronization differential between the
 drive shaft 40 of the selvage insertion apparatus 13 and the weaving
 machine's main shaft 8 were to exceed a given threshold. To avoid this
 problem, the control system 14 can control the drive motor 61 of the
 selvage insertion apparatus 13 as a function of the position of the reed 5
 which in turn is determined by the position of the main shaft 8 in such a
 manner as to preclude the filling thread clamp 17, the insertion arm 18 or
 the filling thread scissors 19 from making contact with the weaving
 machine's reed 5. This allows for controlling the selvage insertion
 apparatus 13 in such a way by a program retrieved from the control system
 14 that the insertion arm 18 will stay as long as possible between the
 warp threads for selvage formation without the risk of collisions in the
 event of variations in synchronization.
 One procedure for such purpose determines the position of the reed 5, for
 instance by the sensor 21, and if thereupon it is found that the
 synchronization differential between the drive shaft 40 and the main shaft
 8 is above a given threshold value, the sub-assembly is controlled in such
 manner as a function of the ascertained position and independently of the
 speed function 76, 76A of the drive motor 61 of the selvage insertion
 apparatus 13 that the filling thread clamp 17, the insertion arm 18 and
 the filling thread scissors 19 are precluded from coming into contact with
 the reed 5. A synchronization differential between the main shaft 8 and
 the drive shaft 40 is ascertained by comparing the signals from the
 sensors 21 and 70. Moreover the positions of the main shaft 8 and of the
 drive shaft 40 at which the above mentioned components of the selvage
 insertion apparatus 13 might touch the reed 5 are fed through a keyboard
 or in another electronic manner into the control system 14. If the control
 system 14 that controls the speed of drive motor 61 as shown in curves 76,
 76A of FIG. 5 determines that there is danger of touching, namely that the
 possible positions of the main shaft 8 and drive shaft 40 are within the
 threshold values stored in the control system 14, the drive motor 61 will
 be controlled to eliminate the mutual synchronization differential. While
 such action may be disadvantageous for the insertion of filling threads,
 it nevertheless offers the advantage of preventing damage to the filling
 thread clamp 17, the insertion arm 18 and the filling thread scissors 19
 and/or the reed 5. Not only would such damage shut down the weaving
 machine for some significant time, but the damaged components of the
 selvage insertion apparatus 13 or a damaged reed 5 would cause quality
 degradation to the fabric.
 In a modified embodiment of the invention, the position of the reed 5 is
 determined not by using the sensor 21 but by using one or several
 proximity sensors 28. Each proximity sensor 28 transmits a signal of the
 position of the reed 5 to the control system 14. One or more such
 proximity sensor(s) 28 may also be used to determine a reference position
 of the reed 5, for instance, the beat-up position.
 The selvage insertion apparatus 11 comprising only one filling thread clamp
 17 and one insertion arm 18 can be designed similarly to the above
 discussed selvage insertion apparatus 13. However the drive bar 36 and the
 associated lever 48 and the cam shape 43 may be eliminated. The selvage
 insertion apparatus 12 comprising two filling thread clamps 17, two
 insertion arms 18 and one filling thread scissors 19 can also be designed
 for the above selvage insertion apparatus 13. In this latter case,
 however, a second drive bar 33 and an associated lever 48 and an
 associated cam shape 44 as well as a second drive bar 31 with associated
 levers 51, 53 and support 52 as well as a connecting rod 55 and a cam
 shape 46 must be provided. Thereupon the control function and operation of
 the selvage insertion apparatus 11 and 12 correspond to that of the
 selvage insertion apparatus 13.
 As regards a selvage insertion apparatus 12 located between two fabrics 22
 and 23, the invention offers the further advantage that, upon
 determination of a defective filling thread, the drive motor 61 of this
 selvage insertion apparatus 12 is controlled in such manner that the
 filling thread scissors 19 of this apparatus 12 will not cut the defective
 filling thread. This feature can be implemented for instance by not
 energizing the drive motor 61 of the apparatus 12 when a filling thread
 detector 75 detects an improperly inserted filling thread and then informs
 the control system 14 of it. Because a defective filling thread is always
 being detected before the filling thread is beat-up, and because the
 selvage insertion apparatus 12 usually acts only after beat-up of such a
 filling thread, cutting this filling thread can be prevented merely by
 timely interrupting the power to the drive motor 61. The end of the
 defectively inserted filling thread is located behind the selvage
 insertion apparatus 12 and can be removed by the method disclosed in U.S.
 Pat. No. 4,898,214.
 If a defectively inserted filling thread is already locked up and must be
 removed, so-called pickfinding motions are carried out whereby the warp
 thread interlacings are undone by the shed-forming elements, with the
 batten 5 being shut down at a predetermined position. The drive motor 61
 of the selvage insertion devices 11, 12, 13 is not controlled during this
 motion and therefore the devices 11, 12, 13 are not activated during the
 pickfinding motion. This feature offers the advantage that the batten 5
 and the shed-forming devices can be moved both forward and backward into
 given batten positions without being affected by the selvage insertion
 apparatus 11, 12, 13, from which the so-called pickfinding motion then can
 be initiated.
 The speed functions 76, 76A of the drive shaft 40 can be fed through an
 input device (not shown) or in any other electronic way into the control
 system 14. Furthermore, the initial and final positions can be fed through
 an appropriate input unit into the control system 14. Obviously the input
 values can be changed any time to implement optimal insertion of filling
 threads.
 The invention is not restricted to the illustrative embodiments shown and
 discussed in relation to the drawings. Other configurations and dimensions
 are quite feasible. The scope of protection is defined solely by the
 attached claims.