Textiles: weaving – Weft manipulation – Weaving with stationary weft supply
Reexamination Certificate
2001-06-06
2002-08-27
Falik, Andy (Department: 3765)
Textiles: weaving
Weft manipulation
Weaving with stationary weft supply
C251S129040
Reexamination Certificate
active
06439271
ABSTRACT:
PRIORITY CLAIM
This application is based on and claims the priority under 35 U.S.C. §119 of German Patent Application 100 28 049.8, filed on Jun. 6, 2000, the entire disclosure of which is incorporated herein by reference.
FIELD OF THE INVENTION
The invention relates to a method for controlling the weft insertion in a jet loom to achieve substantially identical weaving cycle times, and further relates to a jet loom for carrying out such a method.
BACKGROUND INFORMATION
German Patent 30 43 003 discloses a loom arrangement and a method for transporting the weft threads through the loom shed by means of a fluid jet. The basic object of the known method and apparatus is to operate the loom in an optimal manner by controlling the supply of high pressure fluid medium to the weft insertion nozzles during the weft insertion cycle, so that at every time point during the pick or weft insertion, just the right amount of high pressure fluid is provided to the insertion nozzles so that the desired weft insertion velocity or the desired weft insertion transit time is achieved in relation to the rotational speed of the loom. To achieve this, the known method provides for measuring the transport velocity of each inserted weft thread, then providing a signal representative of the measured transport velocity to a control system, which converts this signal to a control signal, which in turn influences or controls the pertinent components of the weft thread transport system for determining the travel velocity of the inserted weft thread.
More particularly, in a detailed embodiment of the known method and apparatus mentioned above, the time required for carrying out the weft transport, i.e. the weft flight time or weft transit time, is continuously measured, and then the average weft insertion time is determined over a plurality of successive picks or weft insertions. The determined average weft insertion time is compared to the desired weft insertion time, and then a signal representative of the determined time difference is provided to a control system in which this signal is converted into a control signal, which in turn influences the components of the weft thread transport system to adjust the weft insertion velocity for subsequent insertion cycles.
Thus, in order to form or obtain a control signal for influencing the components of the weft thread transport system, the known method calls for determining an average weft insertion time over a plurality of successive picks or weft insertions, with respect to each particular type of weft thread. Namely, each different weight, material, density, tightness, or surface characteristic of weft thread will generally have a different weft thread flight time or transit time for a given control condition of the weft insertion system. Thus, the average weft insertion time must be determined separately for each particular type of weft thread.
Then, the determined actual average weft insertion time is compared to the nominal weft insertion time for the respective associated weft thread type. That is a rather complicated and time consuming process and requires the loom operator to have at hand or to determine the necessary parameters of each type of weft thread that is to be processed by the loom.
The above mentioned German Patent 30 43 003 does not disclose any details regarding the type, arrangement and construction of the components of the weft thread transport system. Generally, however, it is known that weft thread transport systems in jet looms include insertion jet nozzles, a supply of pressurized fluid, and magnetic valves for switching, controlling or regulating the volume flows of the pressurized fluid to the respective nozzles.
In a different context, it is known to equip a valve with a piezoelectric drive or valve actuator, for example as disclosed in German Patent 197 23 388 or German Patent Laying-Open Publication 195 47 149. However, it is not known in the prior art to use such piezoelectrically actuated valves as components in a weft thread insertion system of a jet loom. Since the piezoelectrically actuated valves have different operating characteristics magnetically actuated valves, they would not be suggested as a simple replacement or exchange of the magnetic valves that are known in looms.
SUMMARY OF THE INVENTION
In view of the above, it is an object of the invention to provide a loom arrangement and a method for achieving substantially identical weaving cycle times while expressly avoiding the determination of an average weft insertion time per each respective weft thread type. It is a further object of the invention to provide a loom including a valve arrangement, as well as an operating method, which can compensate any time difference arising between the actual weft thread flight time and the nominal or rated weft thread flight time in a rapid reacting manner, substantially in real time on an on-going basis from cycle to cycle during operation of the loom. The invention further aims to avoid or overcome the disadvantages of the prior art, and to achieve additional advantages, as apparent from the present specification.
The above objects have been achieved according to the invention in a method of achieving substantially identical weaving cycle times and particularly weft insertion times for successive weft threads to be inserted into a loom shed of the loom by means of jet insertion nozzles, regardless whether the successive weft threads have identical thread quality parameters or respective differing thread quality parameters. The invention involves the following steps. Data representing at least one thread quality parameter of each weft thread that characterizes the weft thread flight time of this weft thread is stored in a data bank provided in the loom controller of the loom. A respective nominal or rated pressure profile or curve as a function of time that is intended to reliably ensure attainment of the desired nominal weft thread transit or flight time is allocated to the respective characteristic thread quality parameter. The actual thread flight time of each respective weft thread is measured and compared to the rated or nominal thread flight time. The just mentioned comparison results in a signal arising from the difference between the nominal thread flight time and the actual thread flight time, and this signal is delivered to the loom controller, in which the signal is converted into a control signal.
According to a first embodiment of the invention, this control signal is provided to a valve arrangement operatively connected to the weft thread insertion system, e.g. interposed between the pressurized fluid supply and the insertion nozzle or nozzles. Responsive to the control signal, this valve arrangement controls the pressure and/or the quantity of the pressurized fluid being provided to the insertion nozzles, in the sense of a continuous variation of the actual pressure profile of the pressurized fluid provided to the insertion nozzles. In effect, this is also a continuous adjustment of the nominal pressure profile. This can be carried out, for example, either by actually updating the previous stored nominal pressure profile data to a new revised nominal pressure profile to be used for subsequent weft insertions, or by superimposing the control signal over the previous or initial nominal pressure profile to provide a new revised nominal pressure profile signal based on a combination of the control signal and the previous or initial pressure profile.
According to a second embodiment of the inventive method, the control signal generated in the loom controller responsive to the difference between the nominal thread flight time and the actual thread flight time is used to control or adjust the rotational speed of the loom itself. Namely, in this embodiment, the signal resulting from the time difference between the actual thread flight time and the nominal thread flight time is used as a significant value for adapting the rotational speed of the main drive of the loom to the nominal thread flight time. In other words, rathe
Gielen Markus
Schiller Peter
Teufel Dieter
Falik Andy
Fasse W. F.
Fasse W. G.
Lindauer Dornier Gesellschaft mbH
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