Process for manufacturing a semi-finished product with circular knitting machines, in particular for producing undershirts, one-piece body garments, briefs or the like

The present invention relates to a process for manufacturing a semi-finished product with circular knitting machines, in particular for producing undershirts, one-piece body garments, briefs or the like.

As is known from EP-A-0037625, tubular knitted products manufactured with circular knitting machines are used to produce undershirts with no lateral seams. Said products have a substantially uniform knitting along their entire extension, except for any possible ornamental patterns, and in order to produce undershirts they are first cut according to the required length and four portions are subsequently removed at a longitudinal end of the product so as to respectively define the front and back neck-openings and the openings for the arms. When these four portions are removed, four flaps are defined and are subsequently sewn together in pairs so as to obtain the shoulders of the undershirt.

A finishing border is applied along the cutting lines for the removal of the four portions, and the lower end of the undershirt is subjected to a hemming operation with the possible application of an elastic strip.

With this process, the waste consequent to the removal of the portions corresponding to the neck-openings and to the openings for the arms considerably affect production costs, since the thread used for this kind of product is generally of high quality.

The cutting operations furthermore generally require the use of templates to obtain rather precise results, imply relatively long times and in turn affect production costs.

Semi-finished products for producing briefs are also known which are also manufactured with particular circular machines which are similar to circular knitting machines for manufacturing socks and stockings, but with an enlarged needle cylinder.

A first kind of product obtained by a process relating to US-A-4010627 is manufactured by means of a process which substantially consists in initially providing an elastic hem and, after said hem, a portion of tubular knitting, using practically all the needles of the needle cylinder. In a subsequent step, an increasing number of needles belonging to two sets of needles are excluded from knitting; said sets of needles are angularly mutually spaced with respect to the axis of the needle cylinder so as to define, on the lateral surface of the product, two missing portions which correspond to the leg openings of the briefs to be produced. The number of needles excluded from knitting gradually increases up to a maximum value to obtain a widening of the leg opening and to obtain such a length of the portions between the two missing portions as to allow their overlapping and sewing to obtain the crotch of the briefs. The thread or threads are cut, at the beginning of the, sets of needles which are not knitting, i.e. at the edges of the leg openings, by means of appropriate devices fitted to the circular knitting machine being used.

The product is finished by applying an elastic tape or lace to the edges which delimit the leg openings and by sewing the overlapping ends of the portions of knitting arranged between the two missing portions so as to provide, as mentioned, the crotch of the briefs.

This kind of product has the disadvantage that very often, since the thread is cut at the edges of the leg openings, flaws or ladders can occur starting from the edges of the leg openings during the completion of the product, since it is generally pneumatically tensioned, or during its expulsion from the machine or again during the application of the elastic tape, with the consequence of having to reject the product.

A second kind of product obtained by a process relating to US-A-4624115 is produced with a process which instead of providing the cutting of the threads at the edge of the leg openings obtains a complete tubular product, and, at the leg openings, two portions knitted with different stitches with respect to those used for the remaining part of the product are provided, or stitches are knitted along lines corresponding to the border of the leg openings, so as to allow the easy identification of the portions to be successively cut in order to provide the leg openings.

Knitting with different stitches of the entire portions to be removed or the delimiting thereof by means of a line knitted with different stitches with respect to the remaining part of the product allows greater precision and speed in the operations for finishing the product.

This process safely excludes the possibility of flaws or ladders before the finishing operations, but has the disadvantage of requiring considerable waste for each product.

The aim of the present invention is to obviate the above described disadvantages by providing a process for producing semi-finished products usable for producing undershirts, one-piece body garments, briefs or the like, which considerably reduces the product manufacturing costs, reducing losses due to waste, and offers adequate assurances against the onset of flaws or ladders in the product during its manufacture.

Within the scope of this aim, an object of the invention is to provide a process by means of which the finishing operations are extremely simple and rapid.

Another object of the invention is to provide a process which allows to obtain high-quality products.

This aim, these objects and others which will become apparent hereinafter are achieved by a process for manufacturing a semi-finished product with circular knitting machines, in particular for producing undershirts, one-piece body garments, briefs or the like, which comprises making a body of knitting having a tubular extension, characterized in that portions of said body which are to be removed are knitted using more economical threads with respect to the threads used to manufacture the remaining part of the product, and in that: the low-cost threads are meshed with the threads of the remaining part of the product proximate to the border where the knitting of the portions to be removed begins, said threads of the remaining part of the product are subsequently cut, the low-cost threads are meshed with the threads of the remaining part of the product proximate to the border where the knitting of the portions to be removed ends, and said low-cost threads are subsequently cut.

Further characteristics and advantages of the invention will become apparent from the description of some preferred but not exclusive embodiments of the process according to the invention, illustrated only by way of non-limitative example in the accompanying drawings, wherein:

• figure 1 is a lateral elevation view of a product for manufacturing undershirts, manufactured with a first embodiment of the process according to the invention;
• figure 2 is a view of an undershirt obtained with a product of the kind illustrated in figure 1;
• figure 3 is a lateral elevation view of a product for manufacturing undershirts, produced with a second embodiment of the process according to the invention;
• figure 4 is a lateral elevation view of a product for manufacturing one-piece body garments, obtained with a third embodiment of the process according to the invention;
• figure 5 is a view of a one-piece body garment, obtained with a product of the kind illustrated in figure 4;
• figure 6 is a lateral elevation view of a product for manufacturing briefs, manufactured with a fourth embodiment of the process according to the invention;
• figure 7 is a front elevation view of the product illustrated in figure 6;
• figure 8 is a view of a pair of briefs obtained with a product of the kind illustrated in figures 6 and 7;
• figure 9 is a view of an enlarged portion of the various products illustrated in the preceding figures in the region of a portion to be removed which is adjacent to the remaining part of the product.

With reference to the above described figures, the process according to the invention substantially consists in producing, with a circular knitting machine, a body of knitting having a tubular extension of the required length and in knitting the portions of the product intended to be removed, for example to define the front and back neck-openings and the lateral openings for the arms for manufacturing an undershirt, with threads, preferably with a single thread, which are less valuable, i.e. more economical, than the thread or threads used to knit the remaining part of the product.

In order to avoid flaws or ladders in the product, the thread used to knit the portions to be removed is meshed, at the edge of said portions to be removed which are adjacent to the remaining part of the product, with the thread or threads used to knit the remaining part of the product.

More particularly, with particular reference to figure 1, the process according to the invention comprises, for manufacturing a product 1 according to a first embodiment, a first step A during which a first substantially tubular portion of knitting is produced, composed of four first portions 2 which are angularly spaced with respect to one another relative to the axis of the product and are alternated with four second portions 3 intended to be removed. In order to manufacture said first portion of knitting, the needles of the needle cylinder are divided, in a known manner by selection, into four first sets intended to knit the first portions 2, alternated with four second sets of needles intended to knit the second portions 3.

In order to produce the second portions 3 with a lower-cost thread with respect to the threads used for the first portions, an additional thread guide can be provided in a known manner and caused to knit when the needles of the second sets reach the feed of the machine, placing the thread guide at a lower level with respect to that of the thread guides which feed the needles of the first sets and raising the needles of the second sets to a level which is sufficient to engage the thread fed by the additional thread guide but not the thread of the other guides. To mesh the lower-cost thread and the thread or threads used for the remaining part of the product, the last needles of the first sets are caused to engage the thread of the additional thread guide (it is sufficient to activate the additional thread guide a little in advance) and the first needles of the first sets are also caused to engage the thread of the additional thread guide (by deactivating the additional thread guide a little late). Since it is not engaged by the needles of the second sets, the higher-cost thread, which remains engaged with the last needle of the first sets, is cut with a known device provided on the machine at the end of the meshing performed at the beginning of the forming of the second portions. The lower-cost thread, which remains engaged with the last needle of the first sets which took part in the meshing operation, is not engaged by the needles of the first successive sets and is thus cut in a similar manner.

The second portions 3 can also be produced with a lower-cost thread with respect to the thread used for the knitting of the remaining part of the product, if a multiple-feed machine, for example a four-feed machine, is used, by providing two machine feeds in which the higher-cost thread is fed to the first sets of needles which knit the first portions 2 and two feeds in which the low-cost thread is fed to the second sets of needles which indeed knit the second portions 3 alternating a feed of high-cost thread with a feed of low-cost thread. In this case, the meshing between the threads proximate to the edges of the second portions 3 can be performed by selecting, in a known manner, small groups of needles composed of the last needles of the first sets and of the first needles of the second sets, as well as the last needles of the second sets and the first needles of the first sets, according to the rotation of the machine needle cylinder. The needles of these groups knit at all the machine feeds, but contiguous needles in the forming of a same row of knitting start to knit, respectively at the feed which provides the high-cost thread and at the successive feed which provides the low-cost thread. This sequence is reversed in the knitting of the successive row.

In this manner a meshing of the kind illustrated in figure 9 is obtained; in said figure, 31 indicates the high-cost thread, illustrated in white for the sake of simplicity, and 32 indicates the low-cost thread, indicated in black. As can be seen, stitches of knitting with high-cost thread alternated with stitches with low-cost thread occur on a same row of knitting in the meshing region, and a row of stitches knitted by the same needle has the same alternation of stitches with high-cost thread and stitches with low-cost thread. At the end of the knitting of the meshing region, the thread which is no longer engaged by the needles of the first sets or of the second sets is cut in a known manner.

During said first step A it is possible to select the needles, by means of selection devices commonly used in knitting machines for manufacturing socks and stockings, so as to increase the needles of the first sets by subtracting them from the needles of the second sets, or vice versa, so as to obtain the desired configuration for the second and first portions. It is furthermore possible, after a preset number of rows, to divide the needles, by means of known selection devices, exclusively into two first sets and two second sets to end the second portions which correspond to the neck-openings, while the knitting of the second portions, corresponding to the openings for the arms, continues.

After the first step A, a second step B is performed; during this step, a second portion of knitting 4 is knitted in a known manner substantially like the first portions 3.

During the second step B it is possible to use all the feeds of the machine, deactivating any thread guides used to feed the low-cost thread for the knitting of the second portions to those feeds where they were provided, so as to use these feeds, too, to knit the knitting portion 4, achieving a high production speed.

When the product reaches the desired length, knitting is ended and the product is expelled from the machine.

During the first step and a little after the beginning of the second step, stitches 5 arranged proximate to the second portions 3 are knitted; said stitches can be easily distinguished from the others in that they define guiding lines for the finishing operation. Said stitches can be constituted by held stitches or by stitches provided with an additional thread of a different color.

The semi-finished product can subsequently be subjected in a simple and rapid manner to the finishing operations by means of a known machine of the cut-and-sew type by means of which finishing borders 6 are applied, following the guiding lines defined by the stitches 5, along the neck-openings and along the openings for the arms. The machine simultaneously removes the second portions 3 together with the regions of the product which contain the meshes of low-cost and high-cost thread.

The shoulders of the undershirt are then obtained by sewing together the free ends of the first portions 2 in pairs, as illustrated in figure 2, and a folded hem 7 is possibly provided at the lower end of the undershirt.

This last operation of hemming the lower end of the undershirt can be avoided if a second embodiment of the process according to the invention is followed; said second embodiment allows to obtain a product 1a which is already provided with a folded hem along its lower end, as illustrated in figure 3.

More particularly, in this second embodiment, the knitting of the product begins from its lower end with a first step E during which the folded hem 8 with tubular extension is produced. Said hem 8 can be produced in a known manner as for the formation of the upper elastic hem of panty-hoses. If required, the hem 8 can be produced with the addition of an elastic thread so as to obtain an elastic folded hem.

After this first step E, a second step F is performed during which a portion of knitting 9 with tubular extension starting from the elastic hem 8 is produced, and a third step G is performed during which first portions 10 are produced as continuation of the portion 9 alternated with second portions 11 to be removed, substantially as already described with reference to the first embodiment, taking into account the fact that in this second embodiment the product is manufactured starting from the bottom.

In this second embodiment, too, during the formation of the first portions 10 and the portion of knitting 9, proximate to the second portions 11 it is possible to produce stitches 12 executed substantially like the stitches 5 so as to define a guiding line for the successive finishing operations.

With a third embodiment of the process according to the invention it is also possible to manufacture a product 13 for producing one-piece body garments 14, as illustrated in figures 4 and 5.

With reference in particular to figure 4, in this third embodiment the process comprises a first step L and a second step M which are performed substantially like the steps A and B which have already been described with reference to the first embodiment, so as to obtain first portions 15 alternated with second portions 16 to be removed in a first portion of knitting, as well as a second portion of knitting 17 with tubular extension as continuation of the first portions 15.

During the formation of the portion of knitting 17, it is possible to insert, preferably in preset regions, one or more elastic threads so as to obtain for example an elastic band 18 in the region of the abdomen. This can be obtained by feeding the needles of the machine with an elastic thread by means of an appropriate thread guide which is activated when required.

A third step N is subsequently performed during which two third portions 19 are manufactured as continuation of the second portion of knitting 17 and are alternated with two fourth portions 20 intended to be removed to define the leg openings of the one-piece body garment .

The fourth portions 20 are manufactured substantially as already described for the knitting of the second portions 3 of the first embodiment of the process, and said fourth portions 20 are advantageously provided with a number of stitches which increases starting from the second portion of knitting 17, subtracting from the stitches of the third portions 19 so as to obtain an adequate shaping of the leg openings.

In this manner the fourth portions 20, as well as the second portions 16, are manufactured using a thread which is more economical than the thread used for the remaining part of the product, as already described for the first embodiment of the process. Stitches 21, optically distinguishable with respect to the contiguous stitches, as already described for the stitches 5, can be furthermore provided proximate to the fourth portions 20.

When the product reaches the required length, the knitting is ended in a known manner and the product is unloaded from the machine.

In this case, too, the finishing operations can be performed in a simple and rapid manner by means of a cut-and-sew machine which removes the second portions 16 and the fourth portions 20 and simultaneously applies finishing borders 22.

The upper ends of the first portions 15 are sewn together in pairs to obtain the shoulder straps of the one-piece body garment, whereas buttons or the like are applied to the free ends of the fourth portions 20 for their mutual engagement.

With a fourth embodiment of the process according to the invention, illustrated in particular in figures 6 to 8, it is possible to obtain a tubular product for manufacturing briefs.

More particularly, said fourth embodiment of the process comprises a first step P in which a folded elastic hem 40 is produced, by means of the circular knitting machine, similarly to what has already been described with reference to the formation of the hem 8 of the second embodiment, said hem being intended to embrace the user's hips. A second step Q is subsequently performed during which the machine produces, in a known manner, a portion of knitting 41 with tubular extension starting from the elastic hem 40. In a third step R two first portions 42a and 42b are knitted as a continuation of the portion of knitting 41 and are angularly spaced from one another with respect to the axis of the portion of knitting 41; said portions 42a and 42b are alternated with two second portions 43a and 43b intended to be removed and manufactured substantially like the second portions 3, like the second portions 11, like the second portions 16 and like the fourth portions 20 of the previously described embodiments, i.e. by using a thread which is more economical with respect to the thread used for the knitting of the remaining part of the product.

When the first portions 42a and 42b have reached the required length, the knitting of the product is ended in a known manner and the product is unloaded from the machine.

Stitches 44 which are optically distinguishable from the contiguous stitches are advantageously knitted in this fourth embodiment, too, proximate to the border of the portion of tubular knitting 41 and to the first portions 42a and 42b which are contiguous to the second portions 43a and 43b, as in the previously described embodiments.

The product thus manufactured is ready to undergo the finishing operations, which substantially consist in applying a border 45 proximate to the edge of the first portions 42a and 42b by means of a cut-and-sew machine which simultaneously removes the second portions 43a and 43b. The free ends of the first portions 42a and 42b are then superimposed and sewn together, producing the crotch of the briefs, as illustrated in figure 8.

In practice it has been observed that the process according to the invention fully achieves the intended aim, since by knitting the portions of the product intended to be removed using a thread which is more economical with respect to the more valuable thread used to knit the remaining part of the product and by performing the meshing of the low-cost thread with the high-cost thread proximate to the edge of the portions to be removed, the economic losses due to waste are reduced and the risk of flaws and ladders during knitting is safely excluded.

The invention thus conceived is susceptible to numerous modifications and variations, all of which are within the scope of the inventive concept; all the details may furthermore be replaced with technically equivalent elements.

In practice, the materials employed, as well as the dimensions, may be any according to the requirements and to the state of the art.

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 scope of each element identified by way of example by such reference signs.