Lindauer Dornier Gesellschaft Mbh

Lindauer Dornier Gmbh

Dieter Teufel

Adnan Wahhoud

Peter Schiller

Markus Gielen

Valentin Krumm

Peter Czura

Herbert Mueller

Jochen Balken

Matthias Armbrust

Ewald Zimmermann

Wolfgang Metzler

A weaving machine starts-up in slow speed operation during a first weaving cycle following the machine start. To help avoid weft breaks, a method is provided to hold a weft thread inserted into the loom shed during the first weaving cycle. A sensor monitors the weft insertion. The inserted weft thread is held by binding threads at a location downstream from an inlet side of the loom shed, before the weft thread is bound by the warp threads. The binding of the weft thread by the binding threads is carried out dependent on a signal of the sensor.

Method and device for maintaining a weft thread which is introduced into a weaving machine, in particular an air-jet weaving machine, after the starting process

An arrangement for supplying air with a controlled pressure to the main weft insertion nozzles of an air jet loom includes a single servovalve connected between a pressurized air source, an air vent, and a pressure manifold, and individual shut-off valves respectively interposed in branch lines connected from the pressure manifold to the individual nozzles. A pressure sensor measures the actual pressure provided to the manifold. An electronic controller receives a pressure control signal and controls the servovalve responsive to any difference between the pressure control signal and the actual measured pressure signal. The arrangement is simple, economical, and rapidly reacting, to avoid the need of individual throttle valves or pressure regulators for the individual nozzles.

Air supply controller for weft insertion nozzles in an air jet loom

A yarn cutting device for mechanical looms, having two mutually movable blades which are arranged on a mounting surface, at least one of the blades being operable by a drive. The drive is constructed as an electrically energized linear motor, whereby a compact flat construction is achieved which has few movable parts. One of the blade carriers is a rotor of the linear motor.

Linear motor yarn-cutting device for mechanical looms

A valve arrangement of a loom includes valve modules held between flange plates and sharing a common inlet feeding into a common inner valve space. A valve outlet of each valve module leads to an insertion nozzle or nozzle group, and is controlled by a valve disk actuated by a piezoelectric actuator to rapidly dynamically adjust the pressure profile. A quality parameter, characteristic of the thread insertion flight time of each weft thread, is stored in a data bank and has a nominal pressure profile for achieving a nominal thread flight time allocated thereto. The actual thread flight time of each weft thread is measured and compared with the stored nominal thread flight time. A control signal responsive to the time difference is provided to the valve arrangement to control the piezoelectric actuator so as to adjust the pressure and/or the quantity of the pressure medium provided through the valve module to the connected insertion nozzle. Alternatively, the control signal is provided to the main loom rotational drive to adjust the rotational speed of the loom.

Jet loom and method for achieving substantially identical weaving cycle times

A solenoid valve, particularly for use in air nozzle weaving machines, has a valve housing with at least one valve inlet and at least one valve outlet. An electromagnetically actuated valve body is arranged in a passage area between the valve inlet and the valve outlet. In order to permit a fast and operationally reliable exchange of the parts of the solenoid valve subjected to wear, it is provided that a fastening flange, the valve body, as well as the electromagnetic drive together form a first valve subassembly which is subjected to a rapid exchange. The valve housing with its connections forms a second valve subassembly which is fixedly arranged on the machine.

Solenoid valve for air nozzle weaving machines

An electromagnet exhibits in its energization curve (I&equals;f(t)) a characteristic feature or indicator, for example, in the form of a dip (,) in the energization current. This indicator is used to control the operation of the magnet, for example, to synchronize its operation with that of another magnet. In a loom the operation of a weft stop magnet positioned next to a weft prewinder may be synchronized with the operation of a solenoid driving a valve that supplies air to the main weft insertion nozzle and/or relay nozzles. A magnet may also be controlled with reference to rated operation values so that its actual operation value coincides with the rated value or values or at least is maintained within a permissible tolerance range of rated values. The control takes place in closed loop fashion, for example, through the main loom control.

Method for monitoring the operation of an electromagnet in a weft prewinder of a weaving loom

The starting time of a weft thread insertion in a jet loom is automatically adapted to a change in the speed of the main loom drive shaft, in order to assure that the leading end of the weft thread always arrives at the same time at a weft stop motion device at an exit end of a weft insertion channel through the loom shed. For this purpose, the starting time of the weft insertion is advanced when the loom drive shaft rpm is increased and delayed when the rpm is decreased. The advance or delay has reference to a weaving cycle that begins with the opening of a shed and ends when the shed is fully closed. The flight time .DELTA.t.sub.F of a weft thread through the shed is constant. The adaptation is performed in response to measuring the rotational drive shaft angle .alpha..sub.AR at which a weft thread arrives at the weft stop motion device and determining the starting time in such a way that the weft arrival time (t.sub.2, t.sub.4, t.sub.6) always takes place at substantially the same rotational drive shaft angle .alpha..sub.AR.

Method and apparatus for determining the starting time of the weft

In an air jet loom including a stop motion arrangement with first and second light beam sensor devices for detecting the presence of an inserted weft thread, the functionality of the sensor devices is continuously monitored. An inserted weft thread is expected to reach the first sensor device during an angular range (.alpha.1) of one rotation of the main shaft of the loom, whereupon the first sensor device emits a weft arrival signal (S1). In the event of a weft break, the weft thread reaches the second sensor device during the angular range (.alpha.1), whereupon the second sensor device emits a weft fault signal (S2). To monitor the functionality of the first sensor device, an interference signal (S3) emitted thereby during a second angular range (.alpha.2) not corresponding to the first angular range (.alpha.1) is evaluated. To monitor the functionality of the second sensor device, its light beam is positively interrupted by a projection (12') of a machine component (12) during each weft insertion cycle as the reed beats-up the inserted weft thread. Thus, the second sensor device positively emits a test signal during each reed beat-up at a time outside of the first angular range (.alpha.1). The presence, absence or irregularities of the signals (S3) and (S4) are statistically evaluated to determine whether a loom stop is necessary.

Method of monitoring the function of a stop motion arrangement in an air

A method for monitoring the functional reliability of magnetic valves in pneumatically operated systems of an air jet loom, such as the valves for the relay nozzles, allows the failure of such a valve to be quickly detected and corrected. The characteristic progression curve (2) of the valve actuation current (I) as a function of time (t) is monitored for each magnetic valve to detect and evaluate the occurrence, relative timing, and magnitude of a characteristic feature (3), such as a current dip (3), in the increasing portion (2a) of the current progression curve (2). If the characteristic feature (3) is completely missing, or deviates in time or magnitude outside of a tolerance range relative to corresponding nominal values, then a corresponding fault signal is triggered or the weaving process is interrupted. Alternatively, the time of initiating the actuation signal for the respective valve is shifted to bring the actual operation of the valve back into the acceptable tolerance range.

Method for monitoring the proper functioning of electromagnetic air

A running out weft thread end is transferred from a now empty bobbin to a full bobbin during the insertion of a weft thread into the shed of an air nozzle weaving loom from several thread supply bobbins is controlled to obtain a uniform weave even when the thread supply changes from an empty bobbin to a full bobbin. The transfer of the thread is detected and the respective signal is used to temporarily interpose on in a normal thread travelling pattern, a transitional travelling pattern to eliminate disadvantageous influences that affect the weft thread insertion during the transfer of the weft thread from one thread supply to the next. The transitional travelling pattern begins during or immediately after the detection of a thread transfer taking place. The transitional travelling pattern is maintained for a time sufficient to pull a starting amount of weft thread off from the thread supply or until the thread transit time has reached a rated value. Thereafter, the normal travelling pattern controlled by the weft thread insertion program is resumed.

Method for controlling weft thread transfer from empty to full bobbin

Nozzle control device with closed loop control circuit for an air

A weft thread monitor for an air weaving loom with air jets for inserting weft thread yarns of different qualities such as coarse, fine, thick or thin yarns into the loom shed, has an amplifier or comparator controlled in response to control signals which represent the different yarn qualities for providing a loom control signal which is substantially independent of these yarn qualities. The different quality yarns are pulled off from thread storage spools. The air jets of the main nozzles and of relay nozzles are controlled by an air jet insertion control forming part of a central processing unit. The weft thread monitor with its monitoring or sensor element or elements is arranged at the exit side of the air channel formed by profiled reed teeth of the air jet loom. The output of the sensor element is connected to the input of the amplifier or comparator. A uniform output signal from the amplifier or comparator is assured for all types of weft threads regardless of the yarn specific quality, by controlling the amplifier gain or the comparator threshold, for compensation in response to these yarn qualities. Thus, a very thin smooth yarn or a very thick, corase yarn will yield the same resulting output signal.

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Langenargen, Germany

Dieter Teufel