Abstract:
An apparatus ( 1 ) is provided to control the weight of fabric produced by a textile machine ( 2 ), comprising weighting means ( 11 ) of every single fabric piece directly associated to the textile machine dedicated to the manufacture of the same. A procedure is also provided to control the weight of the fabric produced by a textile machine comprising a weighting stage of every single fabric wounded or folded, near the textile machine dedicated to the manufacture of said piece, and to apply to every manufactured piece a printed label suitable to provide at least specific data concerning the piece weight.

Description:
BACKGROUND OF THE INVENTION 
   The object of the present invention is an apparatus and method for controlling the weight of fabric produced by a textile machine, in particular by a circular textile machine. 
   As is known, textile machines, and in particular circular knitting machines for manufacturing knitted fabrics, are generally provided with a pick-up unit for the produced fabric piece, said unit being equipped, beyond with suitable traction rolls, with a winding roll in case the piece is picked up in rolls, or with a cloth folder in case said piece is picked up in laps. 
   In the case of circular knitted machines the pick-up unit consists of a structure turning integrally with the cylinder or needle bed placed above it together with the stretching rolls positioned upstream from said pick-up unit. The rotary motion of the stretching and pick-up unit and of the needle bed usually consists of a mechanical unit or, in more recent times, said motion is driven by an electric motor enslaved in its turn with an electronic unit controlling the correct working of every portion of the textile machine. 
   Since all the fabric pieces, either folded into rolls or piled up in laps, coming out of a knitting mill and successively sent to other departments or factories for finishing or dyeing operations must be assigned their effective weight, it is provided in the prior art to weigh each individual piece in a suitable weighing department. 
   In practice, some pieces produced by a given textile machine are piled up beside said machine and then periodically picked up and conveyed together with other groups of pieces coming from other machines to the weighing department, in which the weight of each piece is written down directly onto an edge of the fabric or on a card which should obviously be attached to the weighed piece. 
   Moreover, the weight of each piece should then be written down onto a summary form. 
   The weighing process briefly described above shows a number of disadvantages. 
   First of all, pieces have weights which can strongly vary with respect to the foreseen values, since the evaluation of the weight of a given piece during its production is generally carried out on the basis of the number of revolutions made by the knitting machine during its manufacture. According to the moisture degree, to the kind of yarn and to the knitted structure, highly different weights having the same number of revolutions and sometimes even going beyond the admissible tolerance field can correspond. 
   In addition, technical times directly required for the detection of the weight of fabric pieces and times required for their conveyance to the weighing departments are quite long. 
   The specific personnel is therefore partially diverted from carrying out more specifically manufacturing operations connected with the working of textile machines. 
   It should be observed that the conveyance and storing in the same place of several pieces coming from different machines can easily involve an exchange between similar pieces assigning to them features, such as the kind of yarn and the batch of raw materials used, which do not correspond to the actual features, thus clearly creating problems in the handling of the produced fabrics. 
   It should eventually be pointed out that the practice to put an indelible mark directly onto an edge of the fabric, which cannot therefore be used, can involve high economic losses in the case of valuable textile fibers. 
   In this situation the technical purpose of the present invention is to provide an apparatus and a method for controlling the weight of fabric produced by a textile machine which can substantially overcome the above-mentioned disadvantages. 
   Within said technical purpose an important aim of the invention is to provide an apparatus and a method allowing to obtain at the output of the textile machines wound or folded fabric pieces showing—with an extremely reduced tolerance field—a pre-established weight, independently from the kind of yarn, and therefore to reach for Instance high degrees of homogeneity of the unfinished products which should then undergo finishing or dyeing operations. Another important aim of the invention is to provide an apparatus and a method allowing to assign with certainty to every piece of manufactured fabric not only its actual weight, but also every other information which could be useful to distinguish it, such as the kind of yarn, the presence of possible defects due to machine stops, and the moisture degree at which the fabric-building process took place, thus avoiding information exchanges among the various fabric pieces due to operators&#39; faults or other reasons. 
   SUMMARY OF THE INVENTION 
   A further aim is to provide an apparatus and a method showing the weight of a given fabric piece immediately at the end of its manufacturing process, thus eliminating dead times required in the prior art because of the weighing operations. 
   The technical purpose and the aims indicates are substantially reached by means of an apparatus and a method for controlling the weight of fabric produced by a textile machine, characterized in that they comprise one or more technical solutions claimed below. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The description of some preferred though not exclusive embodiments of an apparatus for controlling the weight of fabric produced by a textile machine according to the invention is now disclosed as a mere non-limiting example, as shown in the enclosed drawings, in which: 
       FIG. 1  shows a perspective view of a first apparatus according to the invention associated with a circular textile machine, the latter being only partially represented; 
       FIG. 2  shows a front view of the apparatus and of the machine shown in  FIG. 1 ; 
       FIG. 3  is a detail of an enlarged vertical section of the apparatus shown in  FIG. 1 ; 
       FIG. 4  is a broken perspective view of a second embodiment of an apparatus according to the invention associated with a textile machine, the latter being only partially represented; 
       FIG. 5  shows an exploded detail of the apparatus shown in  FIG. 4 ; 
       FIG. 6  shows a front view of the apparatus and of the machine shown in  FIG. 4 ; 
       FIG. 7  shows a broken perspective view of a preferred embodiment of an apparatus according to the invention associated with a textile machine, the latter being only partially represented; 
       FIG. 8  shows a left lateral view of the apparatus shown in  FIG. 7 ; 
       FIG. 9  shows a top view of the apparatus shown in  FIG. 7 ; 
       FIG. 10  shows a block diagram of an apparatus for controlling the weight and of some parts of a textile machine operatively connected to said apparatus; 
       FIG. 11  shows a schematic of a loom containing an apparatus according to the present invention. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   With reference to the figures mentioned above, the apparatus for controlling the weight according to the invention is generally indicated with the numeral  1 . 
   Said apparatus is installed on a textile machine  2 , and in particular on a circular knitting machine, comprising a fixed structure  3  under which at least one needle bed  5  is turnably mounted around a vertical axis  4 , said needle bed  5  consisting for instance of a cylinder and/or dial turning around stationary cans or vice versa. 
   A pick-up unit  6  for the fabric piece is placed under the needle bed  5 , said group being equipped with a winding roll  7 , in case the piece is wound into rolls, or with a cloth folder. 
   The fabric piece is dragged towards the winding roll  7  by at least a traction roll  8 . 
   The pick-up unit  6  can turn around the vertical axis  4  integrally with the needle bed  5  to which it is connected by means of arms  6   a , and it comprises a pair of pillars  9  laterally placed, joined in their lower portions by a pair of parallel bars  10  defining their base. 
   In an original way the apparatus for weight control  1  comprises weighing means  11  ( FIGS. 3 and 5 ) adapted to weigh every single fabric piece and directly associated with the textile machine for the manufacture of said piece. 
   The weighing means comprise in their turn a weight sensor  12 , for instance a load cell, adapted to continuously detect the weight reached by said piece during its manufacturing process and when wound in rolls or laps. 
   The weight sensor  12  is operatively connected to an electronic control group  13  (FIG.  10 ), for instance a PLC, which can check the overall working of the textile machine  2  and in particular of a main electric motor  14  controlling the rotation of the needle bed  5  and the pick-up unit  6 . The electronic control group  13  is advantageously connected, or at least put into communication, with a printer  15  producing self-adhesive labels containing at least the information referring to the weight measured by the weight sensor  12 . Moreover, a display  41  showing the operator the progression of the measured-weight may be provided. According to a first embodiment shown in  FIGS. 1 ,  2  and  3 , the weighing means  11  comprise, beyond the load cell  12 , a support unit  16  formed by a vertically sliding portion  17  and by a fixed base  18  defining a guide for said sliding portion  17 . 
   The latter supports the pick-up unit  6  and shows a portion  17   a  operatively contacted with a flexible wall  12   a  of the weight sensor  12  which is integral in its lower portion with a base plate  19  connected in its turn with the fixed structure  3 . 
   Thus, introducing suitable joints into the arms  6   a  connecting the needle bed  5  with the pick-up unit  6  in order to avoid that the weight of the needle bed is transmitted onto said group, the weight sensor  12  detects a load including the weight of said pick-up unit  6 , which represents the tare, and the weight of the fabric wound onto the winding roll  7 . 
   The vertically sliding portion  17  comprises a support base  20  connected with the pick-up unit  6  and therefore turning integrally with said unit and with the cylinder or needle bed  5 , a slide  21  slidably connected in vertical direction with the fixed base  18 , and turning coupling means  22  placed between a vertical support shaft  23 , constituting a lower extension of the support base  20 , and said slide  21 . The turning coupling means  22  consist of rolling-contact bearings supporting the axial load undergone by the vertical shaft  23 . 
   More to the point, the slide  21  is defined by a substantially glass-shaped cylindrical element housing the vertical shaft  23  and turning coupling means  22  and showing a bottom wall defining said portion  17   a  operatively contacted with the load cell  12 . 
   The fixed base  18  comprises a substantially bush-shaped element  24 , integral with ledges  24  of the fixed structure  3  and slidably coupled with the slide  21  so that the central axis of said slide  21  and therefore the axis of the vertical shaft  23  coincide with the vertical axis  4  of the cylinder or needle bed  5 . 
   Between the fixed base  18  and the slide  21  anti-turning means  25  are provided, said means including a threaded plug  26  introduced into a radial hole of the fixed base  18  and showing a head  26   a  housed in a vertical groove  27  of the slide  21 . 
   The slide  21  shows on its outer side a ring-shaped abutment extension  21   a  abutting against an upper edge  18   a  of the bush-shaped element  18  so as to define a lower run end for the vertical translation of the slide  21 . 
   The abutment extension  21   a  is normally detached of some millimeters from said upper edge  18   a  so as to allow the slide  21  to unload its weight onto the load cell  12 . 
   The above-mentioned support base  20  comprises a circular plate  28  integral in its lower portion with the vertical shaft  23  and a pair of elongated elements  29  peripherally welded to the circular plate  28 . 
   Said elongated elements  29  are connected with the parallel bars  10  defining the base of the pick-up-unit  6 . 
   According to a second embodiment of the present invention shown in  FIGS. 4 ,  5  and  6 , the apparatus for the weight control  1  is placed along the pair of pillars  9 , below the end supports of the winding roll  7  or of the cloth folder. As can be seen in  FIG. 4 , each pillar  9  is divided into two portions, an upper portion  9   a  and a lower portion  9   b . The end supports of the winding roll  7  are mounted onto the upper portions  9   a , in the same way as the traction rolls  9 . The lower portion  9   b  is integral in its lower part with the pair of parallel bars  10  and it is connected in its upper part to the arms  6   a  by means of a support  40 . 
   As shown in  FIG. 5 , the weighing means  11  of the apparatus for weight control  1  are placed as a connection of each upper portion  9   a  with the corresponding lower portion  9   b . In this case two weight sensors or load cells  12  are preferably provided, said sensors or cells being operatively mounted between said portions  9   a  and  9   b  so as to enable weight measurement of the first portion  9   a , of the traction rolls  8 , of the winding roll  7  and of the picked up piece. Each load cell  12  carries out an independent weight measurement. Weight can therefore be detected by only one load cell. 
   The load cell  12  is fixed in its lower portion with an upper end  32  of the lower portion  9   b , for instance by means of at least a first screw  37  engaged into at least a first through hole  30  of the upper end, and into at least a first blind hole  36  in the load cell  12 . 
   In its upper portion the cell shows a flexible wall  12   a  integral with a lower end  31  of the upper portion  9   a , for instance by means of at least a first screw  35  engaged into at least a second through hole  33  of the lower end  31 , and into at least a second blind hole  34  in the load cell. 
   It is also provided for a support element  39 , consisting for instance of a support bolt engaged into a third hole  38  on the upper end  32  of the lower portion  9   b . Said support is not usually in contact with the lower end  31 , but it supports the upper portion  9   a  when the load to be measured is over a certain safety value beyond which the load cell  12  could be damaged. The support  39  acts in practice as a run end. 
   According to a preferred embodiment of the present invention shown in  FIGS. 7 ,  8  and  9 , the apparatus for weight control  1  is placed in a protruding position outside the machine, by means of a pair of support arms  42  extending from the pair of pillars  9  respectively. Both support arms  42  house the weighing means  11 , advantageously carried out by means of load cells  12 . 
   The end supports  43  of the winding roll  7  or of the cloth folding rest on both load cells  12 , so as to allow said cells to detect only the weight of the winding roll  7 , of the supports and of the fabric piece. 
   Advantageously, it could be provided for suitable support elements  39 , analogous to those described in the second embodiment, in order to protect such load cells  12 . 
   As can be seen from  FIGS. 7 and 9 , the machine is advantageously provided with three traction rolls  8 , preferably located on the same horizontal plane as the winding roll  7 , between which the fabric piece is introduced before reaching the winding roll  7 . The vertical pulling strength determined by the fabric piece during its manufacturing stage is thus unloaded onto the traction rolls  8 . It can thus be avoided that said pulling strength is transmitted to the winding roll  7 , which would affect the weight detected by the load cells  12 . 
   Moreover, at least one of sand winding rolls  7  or traction rolls  8  can be provided with two circumferential grooves  44  carried out on the outer edges of the folded fabric piece. Advantageously, as shown in  FIG. 7 , the central traction roll  8 , i.e. the one absorbing the pulling strength of the piece, is provided with grooves  44  on its ends and on the outer edges of the folded fabric piece. These grooves allow to avoid the formation of a permanent fold in the folded tubular fabrics on their edges. 
   The working of an apparatus according to the invention, which has been described above mainly from the structural point of view, is the following. 
   In the first case the load cell  12  continuously detects the weight it supports by means of the sliding portion  17  of the support unit  16 . In the second case the cell directly detects the weight of one of the upper portions  9   a  of the pair of pillars  9 . In the third and preferred form of embodiment the load cell directly detects only the weight of the winding roll  7 , of the end supports  43  and of the piece. 
   In all the embodiments shown the detected weight increases with the piling up of the fabric piece on the winding roll  7 . The value of such weight is transmitted from the load cell  12  to the PLC  13  by means of a signal constituted by an electric voltage. This voltage is compared within the PLC with a preset reference voltage, corresponding in practice to the desired weight the fabric piece should have after manufacturing. 
   When the measured weight reaches a threshold value, the display shows the operator the weight progression so as to simplify its control. 
   When the voltage coming from the weight sensor  12  gets near the value of said reference voltage, the PLC sets the procedure required to stop the textile machine so that the latter stops production exactly on reaching the pre-established weight by the fabric piece formed. It is now possible to carry out a new more precise weight measurement with the machine in a still status and possibly to provide a further advancement of said piece until the desired value is reached. 
   The detected weight and any other information sent to the PLC by the sensors of the machine and/or set by the operator, such as moisture, the kind of yarn used, possible interruptions of production corresponding to manufacturing defects, are immediately written down on adhesive cards issued by the printer  15 . 
   Obviously, the calculation and setting of the desired fabric eight should consider the tare, constituted by the weight of all the parts resting on the weighing device, from which—though only in the first two embodiments—the weight corresponding to the pulling strength exerted by the needle bed onto the piece should be subtracted. 
   It is obviously possible to provide for other embodiments of the present invention. For instance, the weight sensor  12  can be located in such a position as to detect loads exerted onto the connecting arms  6   a , thus weighing a hanging load. 
   The present invention can advantageously and similarly be applied also to a loom  45  or any other textile machine for which it could be useful to weigh the yarn or fabric produced in the manufacturing process. 
   As can be seen from  FIG. 11 , a fabric piece  46  is produced with the loom  45 , said piece being wound around a winding roll  47  supported on its end supports  49  by a pair of support arms  48 . 
   Also in this case load cells  50  implementing an apparatus for controlling the piece weight are placed between the support arms  48  and the end supports  49  of the winding roll  47 . 
   The invention implements a new method which is also an integral part of the present patent. 
   Said method consists in weighing each folded or wound fabric piece near the textile machine manufacturing said piece after the latter has been produced. 
   The method further provides to associate each produced piece with a printed element providing at least the information concerning the weight assigned to said piece. Advantageously, the weighing of each piece produced by a textile machine is carried out continuously, at least during the final manufacturing stage, so as to compare the detected weight, increasing during manufacturing and pick-up of said piece, with a pre-established reference weight. 
   It is preferably provided for a display located near the machine, which shows the progression of the weight when it reaches a first reference value. 
   The textile machine is stopped when the detected weight reaches said pre-established value. 
   Since during the working of the machine the weight measurement is slightly different from the measurement with the machine in a still status, in order to get a more precise measurement it is advantageously possible to provide a first machine stop on reaching a pre-established weight value near the desired one. After said measurement is carried out the machine is re-started until the desired weight, which can be further checked with the machine in a still status, is reached. 
   The invention has important advantages. 
   First of all, the weight of each piece corresponds with a high degree of precision to the pre-established weight, since the latter and no other parameters defines the end of the manufacturing and folding or winding stages of said piece. 
   It should be pointed out that the cards identifying each piece according to its weight and other parameters deemed as necessary to distinguish it are immediately available at the end of its manufacturing and can therefore be applied onto said piece, thus avoiding mistakes and information exchanges among different pieces. 
   It should further be pointed out that the continuous weighing of each piece during its manufacturing can be used for a remote monitoring of production for several textile machines, so as to know exactly in real time the quantity and kind of produced material. 
   Moreover, said information, suitably processed, can be used for storehouse control and for the related certification forms. 
   Other important advantages can be obtained, in particular, in the preferred embodiment of the invention, shown in  FIGS. 7 ,  8  and  9 . 
   First of all, as a matter of fact, a great improvement in weighing precision and reliability can be pointed out, due to tare reduction, the tare consisting only of the winding roll  7  and of its supports, and to the elimination of the vertical pulling strength of the piece which had to be subtracted from the tare weight. 
   Moreover, the preferred embodiment of the invention simplifies the process of removal of the loaded winding roll  7  and its replacement with another roll, thus simplifying the operator&#39;s intervention and making it possible to place a pick-up trolley directly under the roll and possibly to automate said operation. 
   A further advantage of the present embodiment is a reduction of permanent folds on the edges of tubular fabric, since thanks to suitable grooves  44  made on the traction rolls  8 , the usual flattening of said edges can be avoided. A final advantage of the preferred embodiment is the possibility to obtain machines with reduced height, thanks to the fact that the winding roll and the traction rolls are on the same horizontal plane instead of being on the same vertical plane. This greatly simplifies the visual check of the process carried out in the machine by the operator, since the introduction of the yarns into the cylinder is executed at such a height as to be visually accessible also to short people. 
   In practice, the weighing apparatus according to the invention allows to improve the handling of products of textile machines from an operational and organizational point of view, thus simplifying the various operating stages and reducing execution times.