EA041435B1 - METHOD FOR PRODUCING SEMI-FINISHED PRODUCTS FOR MANUFACTURING PRODUCTS, SUCH AS INNER SHOE, INSERT, INVISIBLE SOCK OR DOUBLE THICKNESS SHOES, USING A CIRCULAR KNITTING HOSING MACHINE AND A SEMI-FINISHED PRODUCT OBTAINED BY THIS - Google Patents

Description

The present invention relates to a method for producing semi-finished products for the manufacture of articles such as an liner, heel, invisible sock or double thickness boot on a circular knitting hosiery machine and to a semi-finished product obtained by this method.

In the toe sector, articles are known which are commonly referred to as liner, footprint, shoe insert, mini-sock, stealth toe, etc., which essentially consist of articles intended to be worn on the foot and which cover only the lower part of the leg or, in any case, the part below the ankle.

These products are usually made by using circular knitting hosiery machines, in which the needle cylinder can be actuated by imparting to it a rotational movement about its own axis in two directions of rotation, imparting movement for knitting in at least one system of raising and lowering the needles of the machine, only part of the needles of the machine and removing the remaining needles from the knitting process during the manufacture of part of the product or the entire product.

Depending on the method used to make them, these products are removed from the manufacturing machine as finished products, i.e. products that do not require finishing operations for release for sale, or in the form of semi-finished products that must be subjected to additional processing processes to increase the readiness of the product.

A light boot is also known, in which the upper is made of knitted material. In this case, the upper is usually a plurality of pieces cut from a piece of knitted material, which is then assembled, usually by sewing, and on which the sole is applied.

The aim of the present invention is to provide a method by which it would be possible to produce semi-finished products for the manufacture of products such as liner, footprint, invisible sock or double thickness boot, made on a circular hosiery machine.

Within the scope of this purpose, the subject of the invention is to provide a method by which it would be possible to produce semi-finished products that could be used to produce lightweight shoes with low production costs.

Another object of the invention is to provide a method by which it would be possible to manufacture semi-finished products, which would require the implementation of a limited number of operations, easy to carry out, to obtain a finished product.

A further object of the invention is to provide a process for the manufacture of semi-finished products, which could be carried out on circular knitting hosiery machines of a known type.

Another object of the invention is also to provide a method by which it would be possible to manufacture a finished product that could be used as an liner, footprint, invisible sock or as a light boot.

This object, as well as this and other objects of the invention that will become more apparent later, are achieved and provided by using a method of making semi-finished products for the manufacture of products, for example, an liner, an insole, a stealth sock or a double thickness boot using a circular knitting hosiery machine , containing a needle cylinder located so that its axis is located vertically, and the said needle cylinder contains on its side surface a plurality of axial grooves, in each of which a needle is located, at least one feed mechanism is located around the needle cylinder, and is fed along at least one thread grasped by the needles to form the knitted material distributed over them, means for actuating the needles along the corresponding axial groove, for grasping the thread at least at the said one thread feed mechanism for forming loops of the knitted material, the selection device a, provided for selecting needles to be moved for knitting about said at least one feed mechanism, while said needle cylinder, which can be actuated by imparting to it a rotational movement around said its own axis relative to at least said one a feed mechanism in both directions of rotation for forming a knitted material using at least a part of the needles using at least one of said threads distributed by said at least one feed mechanism, characterized in that it includes at least the following steps:

the step of obtaining the first tubular part of the knitted material by driving the needle cylinder with its continuous rotational movement around its own axis in one direction of rotation;

a reduction step in which a portion of the knitted material is obtained by imparting a knitting movement to a group of adjacent needles near said at least one feed mechanism, actuating the needle cylinder by imparting to it an alternating rotational movement about its own axis and gradually reducing the number of needles advanced for knitting about the mentioned at least one feed mechanism, and removal according to a predetermined sequence of needles located near the side ends of the mentioned

- 1 041435 groups of needles and holding by means of said needles removed from the knitting process, the last formed loops of knitted material, to form the first partial rows of knitted material;

an addition step in which a portion of the knitted material is obtained by imparting a knitting movement to a group of adjacent needles near said at least one feed mechanism, actuating the needle cylinder by imparting to it an alternating rotational movement about its own axis, and gradually increasing the number of needles advanced for knitting, near said at least one feed mechanism, returning for knitting according to a predetermined sequence, which is the reverse of the decrease step, of the needles previously withdrawn from the knitting process at said decrease step, to obtain second partial rows of knitted material connected to said first partial rows of knitted material;

a step of obtaining a second tubular knitted material part by driving the needle cylinder to continuously rotate about its own axis in one direction of rotation;

wherein, in said decrease step and said add step, the respective predetermined sequences, according to which the number of needles of said group of needles, which are pulled out for knitting, is first reduced and then increased, for example, in order to achieve the connection of said first tubular part and said second tubular part of their lateral parts by means of loops of knitted material located at the ends of said first partial rows of knitted material and said second partial rows of knitted material, formed using needles previously withdrawn from the knitting process at said decrease step, and then returned for knitting at said addition step, with the formation the angle between the axes of the said two tubular parts, substantially less than 90°.

Additional characteristics and advantages of the invention will become more apparent after reading the description of a preferred, but not exclusive, embodiment of the method according to the invention and obtaining an article that can be obtained by a method that is illustrated by way of example, not limiting the invention, in the accompanying drawings, in which in Fig . 1 shows a flow diagram of a reduction step followed by an addition step;

in fig. 2 is a schematic view of a part of an article obtained according to the knitting pattern shown in FIG. 1;

in fig. 3 is a diagram of the process according to the invention in the manufacture of a semi-finished product according to the invention;

in fig. 4 is a schematic view of an article obtained according to the process flow diagram shown in FIG. 3, located on a plane and visible from one side;

in fig. 5 is a schematic view of the same product shown in FIG. 4 shown from the opposite side;

in fig. 6-8 are perspective views of the part of the product obtained by the method inserted and laid inside, inside the rest of the part;

in fig. 9 is a perspective view of the product shown in FIG. 6-8 obtained at the end of insertion and inward folding;

in fig. 10 is a side view of a part of the product shown in FIG. 9;

in fig. 11 is a perspective view of an liner that can be obtained by making it according to the method according to the invention;

in fig. 12 is a perspective view of a light boot that can be obtained by manufacturing according to the method according to the invention.

The method according to the invention can be carried out using a circular knitting hosiery of a known type, containing a needle cylinder located so that its axis is located vertically, and provided on its side surface with a plurality of axial grooves, inside each of which a needle is located. At least one feed mechanism is positioned around the needle cylinder and at least one thread is distributed over the needles, which can be picked up by the needles to form a knitted material. The machine is provided with means for driving the needles along a respective axial slot to catch the thread near the aforementioned feeding mechanism and forming loops of the knitted material. In addition, the machine is provided with selection devices for selecting needles to be moved for knitting near the feed mechanism in question. The needle cylinder may be driven to perform a rotational movement about its own axis relative to the feeder in both directions of rotation to form a knitted article by at least a portion of the needles using at least one thread distributed by the feeder.

As described in more detail below, the method according to the invention includes at least the step A of obtaining the first tubular part 2 (see Fig. 3) of knitted material by bringing

- 2 041435 actuating the needle cylinder with its continuous rotational movement around its own axis in one direction of rotation;

reduction step B, in which the knitted part 3 is obtained by moving for knitting about the feeding mechanism of the group of needles in question, actuating the needle cylinder with an alternating rotational movement about its own axis, and gradually reducing the number of needles advanced for knitting about the mechanism in question feeding, withdrawing according to a predetermined sequence of the needle located near the side ends of the group of needles, and holding by means of the needle withdrawn from the knitting process, the last formed loop of knitted material, to form the first partial rows of knitted material;

an addition step C, in which the knitted part 4 is obtained by moving a group of adjacent needles for knitting about the feed mechanism in question, actuating the needle cylinder with an alternating rotational movement about its own axis, and gradually increasing the number of needles extended for knitting about the considered of the feed mechanism returned for knitting according to a predetermined reverse sequence of the decrease B step, where these needles were previously withdrawn from the knitting process during the decrease B step, to obtain second partial rows of knitted material connected near their ends to the first partial rows of knitted material formed in the step of decreasing B;

step D of obtaining the second tubular knitted material portion 5 by driving the needle cylinder to continuously rotate about its own axis in one direction of rotation.

During the decrease step B and during the add step C, the respective predetermined sequences, according to which the number of needles of the group of needles advanced for knitting is first reduced and then increased, are such that the joining of the first tubular part is achieved by the parts 3 and 4 of the knitted material. 2 and the second tubular part 5 with their lateral part about the loops of the knitted material located at the ends of the first partial rows of knitted material and the second partial rows of knitted material, formed by means of needles previously withdrawn from the knitting process at the step of decreasing B, and then returned for knitting at the step adding C, with axes 2a, 5a of two tubular parts 2, 5, between which an angle is formed, substantially less than 90°.

For a better explanation of the implementation of the B subtraction step and the C addition step in FIG. 1 shows a knitting pattern for a piece of product obtained solely by using a decrease step B followed by an add step C. Each black vertical rectangle represents a needle and two rows of knitted material (forward rotation and reverse rotation).

The sequence of decreasing needles thus takes place every two rows of knitted material.

The withdrawal from work (reduction) of the needle or needles can be carried out at the beginning of each row;

at the end of each row;

at the beginning and end of each row.

All the possibilities listed above can be implemented and are functional and differentiated only by the appearance of shaped knitting and loops (see Fig. 2).

In FIG. 1 shows for simplicity only the rectangles corresponding to the needles located at the ends of the group of adjacent needles advanced for knitting in these steps. Rectangles located on the same vertical line refer to the same needle.

As can be seen, during the step of decreasing B, the number of needles moved to receive the thread or threads (only the word thread is mentioned below, and it should be understood that two or more threads can also be fed to the needles at the same time in a manner known per se, depending on requirements), decreases gradually, as can be seen from the inverted, isosceles, trapezoidal shape of the part of the pattern corresponding to this stage of knitting the material.

It should be noted that although at the step of decreasing B from the beginning (from the upper end of the pattern or from the longer parallel side of the inverted trapezoid) to the end of this step (to the shorter parallel side of the inverted trapezoid), the number of needles advanced for knitting near the considered feed mechanism, decreases gradually (not always reduce row by row), i.e. at each reverse rotation of the needle cylinder. Indeed, as can be seen, starting from the first top row, or the longer parallel side of the trapezoid (forming the first partial rows of B1 knit), in which the first needle is withdrawn at the beginning of each one of the two rows (forward rotation and backward rotation), while moving to formation of the second partial rows of knitted fabric B2 (with the direction of rotation of the needle cylinder reversed), two needles located near the lateral ends of the group of needles used to form the previous partial row

- 3 041435 knitted material B1, withdrawn from the knitting process in addition to the needles withdrawn during the formation of a pair of rows of material B1. The same happens when moving to form the third partial row of knitted material B3. However, at the beginning of the formation of the fourth partial row of knitted fabric B4 (new reversal of the direction of rotation of the needle cylinder about its own axis), the two needles that were withdrawn from the knitting process during the formation of the third partial row of knitted fabrics B3 are returned for knitting. When forming the fifth partial row of knitted material B5 and when forming the sixth partial row of knitted material B6, the two needles located near the side ends of the group of needles used to form the previous two partial rows of knitted material are again removed from the knitting process. When forming the seventh partial row of knitted fabric B7, the needles are added, returning for knitting the two needles that were withdrawn when forming the sixth partial row of knitted fabrics B6, and so on.

Pairs of rows can be a different number relative to the number indicated in the example.

It should be noted that when returning the needle to the knitting process, withdrawn from the knitting process during the formation of the previous partial row of knitted material, a connection is created between the loop of the knitted material formed recently when the needle was advanced for knitting before it was withdrawn from knitting process, and the loop of knitted material formed when the needle was returned for knitting. Thus, during the step of decreasing B, so-called intermediate bonds 6 are created between the loops of the knitted material located at the side ends of the first partial rows of the knitted material.

During the addition step C, the knitting process is continued by gradually increasing the number of needles advanced for knitting near the feed mechanism in question, returning the knitting needles that were gradually withdrawn from the knitting process during the decrease step B, as can be seen from the part of the isosceles trapezoid diagram shown in fig. 1 corresponding to this stage of the processing process.

Return to knitting using needles previously withdrawn from the knitting process is carried out according to the following sequence, which is the reverse of the previous sequence, but corresponding to the sequence performed in the decrease step B.

This means that from the beginning of the C addition step (from the shorter parallel side of the trapezoid) to the end of the C addition step (toward the longer parallel side of the trapezoid), the number of needles advanced for knitting near the feed mechanism in question increases in general, despite the fact that upon receipt of every three partial rows of knitted material, the two needles that were returned for knitting during the formation of the immediately previous partial row of knitted material are removed from the knitting process following the reverse sequence of that followed during the decrease step B. According to this sequence, create even at the step of adding C intermediate links 6 between loops of knitted material located near the side ends of the second partial rows of knitted material.

The ends of the partial rows of the knitted material made during the decrease step B (oblique sides of the isosceles trapezoids located on the same side, i.e. knitted with the same needles) are connected or rather tied to each other by means of so-called closing ties 7 Closing links 7 and intermediate links 6 form a series of stitches on the product, alternating with holes, shown schematically in the form of ellipses in the drawings.

In practice, the gradual return to the knitting process during the addition step C of the needles previously withdrawn from the knitting process during the decrease step B makes it possible to obtain a type of knitted material similar to the so-called heel knitting typical of the heel and toe.

However, in a special sequence, during the addition step C and the decrease step B, two parts 3 and 4 of the product produced in these steps are obtained side by side and connected, but their axes (or center lines of the two parts 3 and 4) form an angle substantially less than 90°, as shown in FIG. 2.

It should be noted that the value of this angle can be changed according to the desired shape of the product by modifying the sequence of withdrawing and returning the needles to the knitting process during the decrease B step and the add C step. In the schematic production example described above, during the decrease B step, the number of needles is reduced at each reversal of the direction of rotation of the needle cylinder for three partial rows, and at the step of adding C, the number of active needles is increased accordingly, but at the step of decreasing B, it is possible to reduce (and, accordingly, increase at the step of adding C) the number of active needles for every two or three reverses direction of rotation of the needle cylinder for a predetermined number of partial rows of knitted material.

As already mentioned, in Fig. 1 shows only a schematic view of the B reduction step and the C addition step in a hypothetical product manufacturing process using only these two steps, just to allow an understanding of how the two product parts 3 and 4, consisting of

- 4 041435 partial rows of knitted material, made in two stages B and C, are tied to each other.

In fact, the method according to the invention includes other steps. In FIG. 3 shows a diagram of the implementation of the method according to the invention. Such a diagram can be interpreted as a flat projection of a semi-finished product, usually indicated by the position number 1, obtained by the method according to the invention and ideally cut along horizontal lines, vertical lines and inclined lines, where the vertical lines define the longitudinal cross section of the two tubular parts 2 and 5 of the product;

horizontal lines define the cross section of the product along the same row of knitted material;

oblique lines define the cross-section of the product near the lines of the connection or near the shaped knitting, or connection in the knitted product, the so-called heel type, or more generally with a decrease and a subsequent addition. In the actual product, the slanted lines located on the same side in FIG. 3 and indicated by the same reference number, are connected and mutually overlapped, as they refer to loops of knitted material formed using needles that are gradually withdrawn from the knitting process and then gradually returned to knitting, actually forming the connection of the last loop of the knitted of material formed before the needles were withdrawn from the knitting process, with the first loop of knitted material being formed when they were returned for knitting.

In FIG. 3 lines are formed from shaded rectangles which (each) correspond to a command to actuate the needle near the feeder in question. For simplicity, only the rectangles corresponding to the lateral ends of the various regions constituting the lines along which the product has ideally been cut to create a drawing are shown in FIG. 3. Rectangles along the same vertical ideal line refer to the same needle. When considering the decrease step B and the add step C, the same reference numbers as have already been used in FIG. 1 and 2 have been retained to identify the elements mentioned.

The semi-finished product 1 obtained by the method according to the invention is shown schematically in FIG. 4 and 5. The lines and parts of the product, which in FIG. 3 correspond to the lines and parts of the article shown in FIG. 4 and 5 are designated by the same reference numbers.

As mentioned above, the method according to the invention includes the step A of obtaining the first tubular part 2 of the knitted material.

This step is carried out in a manner known per se by actuating the needle cylinder in a continuous rotational movement about its own axis relative to the feed mechanism in question.

This knitting process is not described further, as it is entirely similar to making a piece for the quarter or part of the leg between the heel and toe of a conventional sock.

Then, step B is carried out, as described above, of the obtained knitted material part 3 or the product to be manufactured.

Before proceeding to the implementation of the addition step C, one part of the group of needles that was used for knitting during the execution of the decrease step B was used for at least two successive knitting processes E, F of the so-called heel type, obtaining two parts of the product, indicated by reference numbers 8 and 9.

These two heel knitting processes E, F are carried out in an essentially known manner using a reduction step followed by an addition step, so that parts of the article are obtained interconnected by so-called shaped knitting lines, indicated by reference numbers 10, 11. It is essential in these heel knitting processes E, F that the needle cylinder is actuated with an alternating movement around its own axis, gradually reducing the number of needles of a predetermined group located nearby, followed by a gradual increase in their number, returning for knitting the needles previously removed from knitting process. Interrupting and re-knitting the material on a part of the needles, located in each case at the ends of a group of needles, produces a line of the product, called a shaped knitting line or decrease line, with stitches alternating with holes, as shown in FIG. 4-12.

Preferably, between these two heel knitting processes E, F, one part of the group of needles used to perform the decrease step B is activated to perform an additional heel knitting process G by actuating the needle cylinder with alternate movement around its own axis.

This additional process of heel knitting G is carried out in an essentially known manner, obtaining a part of the product, designated by the position number 12 and delimited by the shaped knitting line 13.

Immediately before and immediately after this additional heel knitting process, knitting process H is carried out, which is a kind of continuation

- 5 041435 the step of subtracting B and the assumption of the step of adding C, in which the molded area of the product 1 is obtained, resulting in two parts 14, 15 of the product located between each of the two parts 8, 9 obtained as a result of two successive heel knitting processes

E, F and an additional process of heel knitting G.

This formed area contains a line of connection 16 of the parts 14, 15 of the product, constituting a continuation of the closing connections 7 of the parts 3, 4 of the product obtained at the step of decreasing B and at the step of adding C.

Two heel knitting processes E, F and an additional heel knitting process G are carried out using part of the needles used in the decrease step B and the add step C.

Usually, since symmetry is required in the area of the product obtained in the decrease B step and in the addition C step, as well as in the step of performing two consecutive heel knitting processes E, F and in an additional heel knitting process G, part of the group of needles used in two heel in the knitting processes E, F and in the additional heel knitting process G, are located in the center of the group of needles used in the decrease step B and in the add step C.

The second tubular part 5 is also produced in a substantially known manner, as if it were a foot part of a sock.

Typically, the second tubular part 5 can be terminated, in a manner known per se, with a toe part ready for sewing or knitting. Preferably, the seam line or the knitting stitch to close the toe of the second tubular portion 5 in the finished product is located under the wearer's toes.

Generally, prior to obtaining the second tubular part 5, a group of needles that does not belong to the group of needles used for the decrease B step and the add C step, but is actually located opposite it in the needle cylinder, can be used to carry out another heel knitting process I, to obtain part 17, delimited by lowered knitting lines 18.

Semi-finished product 1 (see Fig. 4 and 5) at the exit of the machine looks essentially the same on both sides. As can be seen, the product 1 is essentially two tubular parts 2 and 5 connected by their side part and a contour part 19 located near one end of the product and obtained by performing one or more heel knitting processes, where between the axes 2a and 5a, the two tubular parts 2 and 5 form an angle substantially less than 90°.

After removing the product 1 from the manufacturing machine, it is subjected to a series of operations to obtain the finished product.

More specifically, as shown in FIG. 6, the part 4 of the article 1 obtained during the addition step C is pushed into the inside of the article part 3 obtained during the decrease step B by folding the article 1 along the joining lines, i.e. along the closing ties 7 of these two parts 3, 4 of article 1. The part 9 obtained using one of the heel knitting processes F is also pushed inside the other part 8 provided with the other one of the parts obtained using the heel knitting process E, and by folding the part 12 obtained using the additional heel knitting process G near the center line so that it looks like a back tongue.

The second tubular part 5 is then folded inside the first tubular part 2 in such a way that a boot or sock of double thickness is obtained, in which the lines of connection, i.e. the closing links 7 of the article part 3 made in step B with the article part 4 made in step C define the side opening 20 of a boot or sock of double thickness for the introduction of the foot.

More specifically, the first tubular part 2 is located on the outside, and similarly, the part 8 attached to it, obtained using the heel knitting process E, is also located on the outside. The other part 9, obtained using the heel knitting process F, is located inside and superimposed on part 8. Part 12 is widely spaced, i.e. protrudes partly outward and partly inward, mutually connecting parts 8 and 9. Parts 3, 4, obtained in the step of decreasing B and adding step C, are located respectively outside and inside the region in which the opening 20 for introducing the leg is formed, and constitutes the lateral and the lower region relative to said opening 20 for the introduction of the leg. If a particularly large extension of these areas is required, then on circular knitting hosiery machines of the known type, on which the selection of the needles to be moved for knitting during the rotational movement of the needle cylinder in one direction is carried out during the immediately preceding movement in the opposite direction, the method can be used. of the type described in patent application 102018000002290, registered in the name of the same applicant, which has not yet been published.

Part 17, obtained using the heel knitting process I, by means of needles belonging to the group of needles located opposite the group of needles used in the decrease step B and the addition step C, also protrudes partly inside and partly outside the sock or boot, representing the front tongue.

Advantageously, between the inside and outside of the sock or boot thus obtained, or in the thread used to make it, it is possible to use

Claims (9)

for example, a binder, for example a binder that can be reactivated by heating, to stabilize the interconnection of the two parts: the inner layer and the outer layer, constituting the sock or shoe. The manufacture of the sock or boot is completed by closing the toe, in a manner known per se, i.e. the free end of the second tubular part 5, and by cutting and closing, for example by sewing or other known method, the free end of the first tubular part 2. If the product is intended for the manufacture of a boot, then on the lower side, i.e. on the side of the article opposite the opening 20 for the introduction of the leg, it is possible to apply, for example, a binder for bonding or to mold the sole 21. In this case, the operation to close the free end of the first tubular part 2 can be combined with the operation of applying the sole 21. In practice, it has been found that by using the method according to the invention, the set goal is fully achieved, since when using it, it is possible to obtain semi-finished products for the manufacture of products, such as an inner shoe, an insole or a double-thickness sock, using a circular knitting hosiery, with the execution a reduced number of operations, and thus a reduced cost, required to obtain a finished product. An additional advantage of the method according to the invention is that it can be used to produce semi-finished products that can be used to make a low cost lightweight boot. The method, and the semi-finished product that can be obtained by using it, are thus proposed, susceptible to a number of modifications and variations, all of which fall within the scope of the appended claims; all details can be, moreover, replaced by other, technically equivalent elements. In practice, the materials used, as well as the dimensions, may be any according to the requirements and the state of the art. The solutions disclosed in Italian Patent Application No. 102018000007798, to which this application claims priority, are hereby incorporated by reference. Where a reference number follows the technical features mentioned in any claim, those reference numbers are included for the sole purpose of enhancing the clarity of the claims and, accordingly, such reference numbers do not have any restrictive effect on the interpretation of each the element identified by way of example with reference to that position number. CLAIM 1. A method of obtaining semi-finished products for the manufacture of products such as an inner shoe, an insole, an invisible sock or a double thickness boot, using a circular knitting hosiery machine containing a needle cylinder located so that its axis is located vertically and having on a plurality of axial grooves on its side surface, in each of which a needle is located, as well as at least one feed mechanism located around the mentioned needle cylinder, and at least one thread captured by the needles to form a knitted material distributed over the needles, means provided for actuating the needle along the corresponding axial groove for grabbing the thread near the mentioned at least one feeding mechanism and forming loops of the knitted material, the selection devices provided for selecting the needles to be moved for knitting near the mentioned at least one feeding mechanism, and the mentioned needle cylinder the other is configured to actuate it to impart rotational movement around its own axis relative to said at least one feed mechanism in both directions of rotation to form a knitted material by using at least a portion of said needles using said at least one thread, distributed by said at least one feed mechanism, characterized in that it includes at least the following steps: step (A) obtaining the first tubular part (2) knitted material by driving the needle cylinder with the message to him a continuous rotational movement about its own axis in one direction of rotation; a reduction step (B) in which a knitted material part (3) is obtained by imparting a knitting movement to a group of adjacent needles near said at least one feed mechanism, actuating the needle cylinder by imparting to it an alternating rotational movement about its own axis and gradually reducing the number of needles advanced for knitting near said at least one feed mechanism, withdrawing according to a predetermined sequence of needles located near the side ends - 7 041435 said group of needles, and holding by means of said needles withdrawn from the knitting process, the last formed loop of knitted material, to form the first partial rows of knitted material; an addition step (C) in which a knitted material part (4) is obtained by imparting a knitting motion to a group of adjacent needles near said at least one feed mechanism, actuating the needle cylinder by imparting to it an alternating rotational motion about its own axis and gradually increasing the number of needles advanced for knitting near said at least one feeder, returned for knitting, according to a predetermined sequence, which is the reverse of the sequence of said decrease step (B), needles that were previously withdrawn from the knitting process at said step subtraction (B), to obtain the second partial rows of knitted material, connected with the first mentioned partial rows of knitted material; step (D) obtaining the second tubular part (5) of the knitted material by driving the needle cylinder by giving it a continuous rotational movement about its own axis in one direction of rotation; wherein, in said decreasing step (B) and said adding step (C), the respective predetermined sequences, according to which the number of needles of said needle group advanced for knitting is first reduced and then increased, is such that the connection of said first tubular part (2) and said second tubular part (5) by their lateral part by means of loops of knitted material located at the ends of said first partial rows of knitted material and said second partial rows of knitted material, formed by means of needles previously withdrawn from the knitting process at the mentioned reduction stage (B) and then returned for knitting at said addition step (C), wherein between the axes (2a, 5a) of said two tubular parts (2, 5) an angle substantially less than 90° is formed. 2. The method according to claim 1, characterized in that in said step of decreasing (B), despite the reduction in the total number of needles advanced for knitting near said at least one feed mechanism, when obtaining some partial rows of knitted material, the needles are withdrawn from the knitting process upon receipt of the previous partial rows, return for knitting. 3. The method according to claim 1, characterized in that in said step of adding (C), despite the increase in the total number of needles advanced for knitting near said at least one feed mechanism, when receiving some partial rows of knitted material, the needles returned for knitting upon receipt of the previous partial rows of knitted material, are removed from the knitting process. 4. Method according to one or more of the preceding claims, characterized in that after said decrease step (B) and before said add step (C), at least two successive heel knitting processes (E, F) are performed by using part of said group of needles by driving the needle cylinder by imparting to it an alternating rotational movement about its own axis. 5. The method according to claim 4, characterized in that between said two successive heel knitting processes (E, F) a part of said group of needles is activated to perform additional heel knitting processes (G) by actuating the needle cylinder by communicating it alternately rotational motion around its own axis. 6. Method according to claim 4 or 5, characterized in that the part of the needles of said group of needles, by means of which said two successive heel knitting processes (E, F) are carried out, is centrally located in said group of needles. 7. A method according to one or more of claims 4 to 6, characterized in that the part of the needles of said group of needles, by means of which said additional heel knitting processes (G) are carried out, is centrally located in said group of needles. 8. A method according to one or more of the preceding claims, characterized in that said second tubular part (5) of the knitted material is terminated by knitting the toe of the sock. 9. The method according to one or more of claims 4 to 7, characterized in that the part (4) of the product obtained during the addition step (C) is pushed inside the part (3) of the product obtained during the subtraction step (B), by folding the product along the closing links (7) of these two parts (3, 4) of the product, and by the fact that the said second tubular part (5) is placed inside the said first tubular part (2), while one part (9) of two parts , obtained by performing one of two successive heel knitting processes (E, F), closest to the part (4) of the product obtained during the execution of the addition step (C), is pressed against the inside of the other part (8) obtained by performing another one from two successive heel knitting processes (E, F), obtaining a type of shoe or sock of double thickness, in which the closing ties (7), which connect the part (3) of the product made in the step of decreasing (B), with the part (4) of the product made at the stage e additions (C), limit the opening (20) on the side for putting on the boot -