EP3339487A1

EP3339487A1 - Method of controlling yarn selection for weaving systems

Info

Publication number: EP3339487A1
Application number: EP17205244.1A
Authority: EP
Inventors: Luca Gotti; Pietro Zenoni
Original assignee: LGL Electronics SpA
Current assignee: LGL Electronics SpA
Priority date: 2016-12-14
Filing date: 2017-12-04
Publication date: 2018-06-27
Anticipated expiration: 2037-12-04
Also published as: CN108221141A; EP3339487B1; CN108221141B; IT201600125999A1

Abstract

A loom (T) receives multiple yarns (C1, C2, ..., C5) from respective feeders (Fl, F2, ..., F5) which are activated alternately according to a preestablished pattern, each feeder having associated with it a first identification value (NFdr) which corresponds to its operative position with respect to the loom, a feeder-specific second identification value (NFdrPP), a sensor (Q) that detects the unwinding of yarn, and a control unit (SPDREG) that adjusts the operation of the feeder on the basis of a signals received from the sensor (Q), the loom (T) periodically sends to the feeders (Fl, F2, ..., F5) messages (PPMsg0, PPMsgl, ..., PPMsg5) which contain preview selection information related to the second identification value (NfdrPP); the control unit (SPDREG) monitors in real time the amount of yarn unwound from the feeder by way of the sensor (Q) and, if it exceeds a preestablished threshold (MinPuls) for a preestablished minimum number of insertions (M), it automatically sets the second identification value (NFdrPP) to the first identification value (Nfdr).

Description

The present invention relates to a method of controlling yarn selection for weaving systems.
As is known, in a generic weaving system, a loom can receive a plurality of yams from respective feeders which are activated alternately on the basis of a preset pattern on the loom. Between the feeders and the loom is a device known as a "presenter", which on the basis of selection information positions the selected weft in front of the gripper of the loom so that it can be picked up.
The "pattern preview" function is also known, by way of which the loom transmits the selection information to the feeders in advance.
By virtue of this function, the feeder that is about to be selected can perform some preliminary operations so as to improve the process: for example, for a striped pattern, the feeder can conveniently start before the moment of selection so as to reduce acceleration and, as a consequence, contain the stress on the yarn.
In addition to the advance selection information, the loom sends the feeder other information, including the length of weft inserted and the speed of weaving. Since the feeder adjusts its winding speed on the basis of these three items of information, the precision/accuracy of these is critical to the successful result of the weaving process.
However, as is well known to the person skilled in the art, the advance selection information is susceptible to errors/changes in the arrangement of the feeders during the step of setting up the weaving process by the user.
In particular, the selection of the feeder passes through two association tables. The first table associates each one of the yarns in input to the loom, identified in the jargon by a "color", with a selector of the presenter, and the second table associates each one of the selectors of the presenter with a respective feeder.
As is well known to the person skilled in the art, such twofold passage can result in errors on the part of the user who, for example, can invert the position of two feeders without considering that, in so doing, the advance selection information will not correspond to the actual selection.
Such errors, in addition to defeating the advantages of the pattern preview function, can actually compromise the correct execution of the weaving process. For example, the exhaustion or over-accumulation of yarn can occur on one or more of the feeders.
Therefore, the aim of the present invention is to provide a method of controlling yarn selection for weaving systems, in which the correct execution of the pattern preview function is substantially not susceptible to errors/changes in the connection of the feeders by the user.
This aim and other objects of the present invention, which will become better apparent hereinafter, are achieved by the method having the characteristics recited in claim 1, while the dependent claims define other characteristics of the invention which are advantageous, although secondary.
Now the invention will be described in more detail with reference to a preferred but not exclusive embodiment thereof, which is illustrated for the purposes of non-limiting example in the accompanying drawings, wherein:

Figure 1 schematically illustrates a weaving apparatus to which the method according to the invention can be applied;
Figure 2 schematically illustrates a feeder of the weaving apparatus in Fig. 1;
Figure 3 is a diagram showing sequences of signals generated over time in a weaving process using the method according to the invention.

Figure 1 shows a generic weaving apparatus in which a loom T receives a plurality of yams, e.g., five yarns, each one identified with a respective "color" C1, C2, ..., C5, from respective feeders F1, F2, ..., F5. The feeders F1, F2, ..., F5 pick up the yarn from respective distaffs R1, R2, ..., R5 and are activated alternately by the loom T on the basis of a preestablished pattern.
Between the feeders F1, F2, ..., F5 and the loom T is a presenter P which is provided with selectors S1, S2, ..., S5 that, on the basis of selection information, alternately position the selected yarns in front of the gripper (not shown) of the loom T in order to be picked up.
Figure 2 shows, in more detail, any one of the feeders F1, F2, ..., F5, which is designated with F and feeds the generic yarn C picked up by the generic distaff R.
The feeder F comprises a drum D on which a motorized flywheel W winds the yarn C originating from the respective distaff in the form of loops that constitute a reserve. In a way that is known per se, the feeder F is fitted with an unwinding sensor Q, typically an optical sensor, which generates an unwinding pulse UWP for each loop or fraction of a loop of yarn unwound from the drum.
Operation of the feeder F is controlled by a control unit SPDREG, which adjusts the speed with which the yarn C is wound on the drum D on the basis of information received from the loom by way of a BUS B.
Each one of the feeders has a first identification value, NFdr, associated with it, which corresponds to its operative position with respect to the loom. In the example described herein, NFdr is a numeric value from 1 to 5 which identifies the position in which the feeder is connected to the electric power supply box.
In the example diagram in Fig. 3, the FdrSel field shows the selection of the feeders during five consecutive insertions Pick N, Pick N+ 1, ..., Pick N+4, after the insertion Pick N-1. In the example shown, during insertion N the feeder connected to position 2 is selected, during insertion N+1 the feeder connected to position 2 is selected, during insertion N+2 the feeder connected to position 5 is selected, during insertion N+3 the feeder connected to position 2 is selected, and during insertion N+4 the feeder connected to position 5 is selected.
In a preset point before the start of each insertion cycle (e.g., at about 300° of machine rotation, θ in the example in Fig. 3), the loom sends a pattern preview message PPMsg0, PPMsg1, ..., PPMsg5, containing the advance selection information for the next five insertions Pick N, Pick N+1, ..., Pick N+4.
To this end, each one of the feeders has a second identification value, NFdrPP, associated with it, which identifies it for the purposes of the pattern preview function. Usually, NFdrPP is a numeric value that during configuration is set to be equal to NFdr: in essence, the feeder connected to position 1 of the electric power supply box will be identified as feeder 1 in the pattern preview messages as well, and the same is true for the other feeders.
In the example shown in Fig. 3, therefore, the first pattern preview message PPMsg0 should contain the information 2-2-5-2-5.
As discussed in the introduction to the present description, however, during the configuration of the weaving process it can happen that a feeder becomes connected in an incorrect position of the electric power supply box owing to an error in reading the association tables, or it is deliberately moved without considering the negative consequences that this entails for the pattern preview function.
For example, if the feeder with NFdrPP = 1 is moved to position 2 (NFdr = 2) of the electric power supply box, the pattern preview message PPMsg0 in the example in Fig. 3 will contain the information 1-1-5-1-5, but the selection FdrSel in those five insertions will be 2-2-5-2-5. As a consequence, the pattern preview function for that feeder will not be operative.
According to the invention, in order to correct the aforementioned possible inconsistences between the pattern preview message and the actual selection FdrSel, the control unit SPDREG of the feeder F monitors in real time the number of pulses UWP generated by the respective unwinding sensor Q at each insertion and, if the number of pulses UWP exceeds a preestablished threshold value MinPuls for a preestablished minimum number of insertions M, it automatically corrects its NFdrPP value so as to correspond to NFdr.
Preferably, the threshold value MinPuls is equal to a percentage K comprised between 50% and 70%, preferably 60%, of the length of weft inserted at each insertion.
The threshold value MinPuls can advantageously be calculated using the following formula: $MinPuls = Int (Ylen / FdrC * K)$
where Ylen is the weft length inserted at each insertion and FdrC is the winding circumference of the feeder.
For the purposes of example, if Ylen = 1900mm and FdrC = 440mm, MinPuls is equal to 2.
The minimum number of insertions can conveniently be equal to 3.
Applying the above mentioned numeric values to the example in Fig. 3, we see that the unwinding sensor Q generates a number of pulses that exceeds MinPuls = 2 (respectively 4, 5 and 4 pulses) in at least three insertions (N, N+1 and N+3). Therefore, starting from insertion N+4, the value NFdrPP of the feeder in question is automatically changed from 1 to 2.
A preferred embodiment of the invention has been described, but obviously the person skilled in the art may make various modifications and variations within the scope of the appended claims. In particular, although in the embodiment described herein the unwinding sensor Q is shown as a piezoelectric sensor accommodated on the yarn guiding bush arranged at the outlet end of the feeder, other types of sensors can also be used, e.g., reflection photocell sensors arranged so as to detect the movements of the yarn on the drum. In general, the signal indicating the unwinding of yarn may be continuous instead of impulse-based, using sliding sensors of different type.
The disclosures in Italian Patent Application No. 102016000125999 ( UA2016A009002 ) from which this application claims priority are incorporated herein by reference.
Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly, such reference signs do not have any limiting effect on the interpretation of each element identified by way of example by such reference signs.

Claims

A method of controlling yarn selection for weaving systems, wherein a loom (T) receives a plurality of yarns (C1, C2, ..., C5) from respective feeders (F1, F2, ..., F5) which are activated alternately by the loom (T) according to a preestablished pattern, each one of said feeders having associated therewith:
- a first identification value (NFdr) which corresponds to its operative position with respect to the loom,

- a second identification value (NFdrPP) which is specific to the feeder,

- sensor means (Q) adapted to detect the unwinding of yarn from the feeder,

- a control unit (SPDREG) adapted to adjust the operation of the feeder on the basis of signals received from said sensor means (Q),
said loom (T) periodically sending to the feeders (F1, F2, ..., F5) pattern preview messages (PPMsgO, PPMsg1, ..., PPMsg5) which contain preview selection information related to said second identification value (NFdrPP),
characterized in that, in order to correct any inconsistencies between said messages (PPMsgO, PPMsg1, ..., PPMsg5) and the actual selection (FdrSel), said control unit (SPDREG) monitors in real time the amount of yarn unwound from the respective feeder by way of said sensor means (Q) and, if said amount of unwound yarn exceeds a preestablished threshold value (MinPuls) for a preestablished minimum number of insertions (M), it automatically sets said second identification value (NFdrPP) to said first identification value (NFdr).
The method according to claim 1, characterized in that said threshold value (MinPuls) corresponds to a percentage (K) of the length of weft inserted at each insertion.
The method according to claim 2, characterized in that said percentage (K) is comprised between 50% and 70%.
The method according to claim 3, characterized in that said percentage (K) is equal to 60%.
The method according to any one of claims 1-4, characterized in that said sensor means (Q) are adapted to generate a pulse per each loop unwound from the drum, and said threshold value is equivalent to a minimum number of pulses MinPuls calculated according to the formula: $MinPuls = Int (Ylen / FdrC * K)$
where Ylen is the weft length inserted at each insertion and FdrC is the winding circumference of the feeder.
The method according to any one of claims 1 to 5, characterized in that said minimum number of insertions is equal to 3.