Textiles: weaving – Weft manipulation – Weaving with stationary weft supply
Reexamination Certificate
2000-07-25
2001-02-13
Worrell, Danny (Department: 3741)
Textiles: weaving
Weft manipulation
Weaving with stationary weft supply
C139S336000, C138S036000
Reexamination Certificate
active
06186191
ABSTRACT:
PRIORITY CLAIM
This application is based on and claims the priority under 35 U.S.C. §119 of German Patent Application 199 36 071.5, filed on Jul. 30, 1999, the entire disclosure of which is incorporated herein by reference.
FIELD OF THE INVENTION
The invention relates to a monitoring arrangement for fluid jet looms having flexible pressure hoses as components of a weft thread insertion system, whereby these pressure hoses respectively connect at least one pressure source with at least one electrically actuatable magnetic valve, and/or connect at least one electrically actuatable magnetic valve with fluidic weft insertion devices, e.g. fluid jet nozzles.
BACKGROUND INFORMATION
Fluid jet looms conventionally include a source of pressurized fluid, a main or primary weft insertion nozzle and a plurality of auxiliary weft insertion nozzles, as well as a plurality of individual flexible pressure hoses that connect the pressure source to the several nozzles. Electrically actuatable magnetic valves are also typically interposed between the pressure source and the nozzles, in order to control the supply of pressurized fluid from the source to the nozzles, according to a program being executed by the general loom controller. In this regard, the main weft insertion nozzle inserts a weft thread into an open loom shed as pressurized fluid is supplied to this nozzle, and then the auxiliary nozzles carry the inserted weft thread across the width of the open shed, for example along a weft insertion channel provided in the reed of the loom. In a typical air jet loom, the pressure source is a source of pressurized air, and the nozzles are corresponding air jet nozzles. Alternatively, a liquid, such as water may be provided from the pressure source to drive appropriate water jet nozzles.
In the operation of such fluid jet looms, the flexible pressure hoses are subjected to a great variety of loads and stresses during the weaving process. Such loads and stresses include bending loads and stresses at the terminal hose connections, as well as pressure loads and stresses of the entire hose and its connections as a result of the repetitive increasing and decreasing of the pressure within the hose during the course of the weaving operation. Since the magnetic valves controlling the flow of the pressurized fluid cycle open and closed during the weaving operation, there is a corresponding drastic and rapid variation of pressure in the associated pressure hoses. Also, the vibration and motion of various mechanical components of the loom cause corresponding vibration and motion of the pressure hoses and the hose connections provided at the ends of the hoses.
These various loads and stresses cause long term fatigue of the pressure hoses and their terminal hose connections, as well as sudden drastic failure such as a rupture or leakage due to an overload or the like. More generally, the above mentioned loads and stresses lead to various types of defects in the pressure hoses, from leakage points such as pinpoint holes or ruptures along the length of the hose, to a complete rupture or separation of the hose from its terminal hose connection, for example. The pneumatic or hydraulic fluid (e.g. air or water) leaking out of the hose as a result of such defects causes a reduction of the effectiveness of the associated main weft insertion nozzle and/or auxiliary nozzles connected to the affected hose.
Such a reduction in the operating effectiveness of the fluid nozzles due to defects in the pressure hoses has never yet been monitored or detected in conventional looms up to the present date. The reduction in the operating effectiveness of the weft insertion system necessarily ultimately leads to problems and defects in the weft insertion, which may, however, not be immediately recognized after their occurrence by the operator of the loom. Rather, there is a significant danger that the reduction in weft insertion effectiveness will go unnoticed and uncorrected for an extended period of time during the operation of the loom. As a result, defective weft insertions can be carried out during this period time, and the resulting defectively inserted weft threads will remain as permanent weave defects in the finished woven fabric. This is especially true when the above mentioned defects in the pressure hoses result in only minor leakage at first, but become progressively worse over time, because such a progressive worsening may not be recognized. Thus, the reduction in the weft insertion effectiveness and the corresponding increase in weft defects that is caused by a defective pressure hose in the weft thread insertion system of the loom can lead to the production of a considerable quantity of defective reject fabric, until eventually the operator of the loom notices the defects in the woven fabric and shuts down the loom.
SUMMARY OF THE INVENTION
In view of the above it is an object of the invention to provide a system and a method for carrying out a permanent monitoring of the proper functionality of the pressure hoses, and particularly the pressure hoses included in the weft thread insertion system of a fluid jet loom, in order to ensure that any defect or deficiency in the functionality of the hoses is immediately detected and indicated, and may be used to trigger a stop 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 an improved monitoring arrangement in a loom provided with a fluid jet weft insertion. The overall apparatus comprises a pressurized fluid supply arrangement (e.g. including a pneumatic or hydraulic pressure source and at least one electrically actuatable magnetic valve), at least one fluid jet nozzle arrangement (e.g. including a fluid jet nozzle for inserting a weft thread into a loom shed and at least one fluid jet nozzle for drawing and tensioning the inserted weft thread at the downstream side of the weaving width), and flexible pressure hoses connecting the pressurized fluid supply arrangement (e.g. the valves) to the nozzles. Especially according to the invention, the pressure hoses include a base hose wall material such as a rubber or synthetic plastic hose wall, as well as at least one electrical conductor arranged on or in the hose wall. The electrical conductor provided in or on the pressure hose is connected directly or indirectly to a detection circuit, which may be a separate circuit or may be incorporated in the loom controller. When a defect occurs in a pressure hose, the electrical conductor in the hose is broken, interrupted or otherwise altered. As a result, an electrical current conducted through the conductor is interrupted or altered, which can be detected by the loom controller or separate detection circuit, which then releases a signal indicating a defect in the respective pressure hose, or directly triggers a loom stop.
The above objects have further been achieved according to the invention in a method of operating the above described system or arrangement. In this method, an electrical current or signal is conducted through the electrical conductor provided in the pressure hose. An electrical characteristic of the electrical signal is continuously or intermittently monitored by the provided detection circuit or directly by the loom controller. In this context, the electrical characteristics are, for example, the magnitude of the current conducted through the electrical conductor of the hose, the voltage measured along the length of the hose, the resistance measured along the length of the hose, or the resonant frequency of a resonant circuit including the electrical conductor as a circuit component. Any variation of the measured electrical characteristic outside of an acceptable range, or beyond an acceptable threshold, is interpreted as an indication that a defect or rupture has occurred in the respective associated pressure hose. As a result, a defect signal is triggered or release
Dornier Peter D.
Mueller Herbert
Fasse W. F.
Fasse W. G.
Lindauer Dornier Gesellschaft mbH
Worrell Danny
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