FR3014010A3 - MACHINE FOR PRODUCING CARDBOARD TUBES - Google Patents

Abstract

A machine for producing cardboard tubes through the helical winding of one or more partially overlapping cardboard strips, comprising a plurality of forming groups which are supported by the same structure (S) and are arranged horizontally and vertically staggered with respect to each other; each of said forming groups (1, 2) comprises means for producing a cardboard tube so that the machine is capable of producing a plurality of cardboard tubes simultaneously.

Description

The present invention relates to a machine for producing cardboard tubes, in particular for the paper converting industry.

It is known that in the carton converting industry, machines for producing cardboard tubes, also called mandrel winders, produce a rigid tube made from cardboard (also called "mandrel") on which the paper is wound to form a roll or "log", which is then substantially divided into several elements of predefined length to obtain rolls of toilet paper, rolls of paper towels, etc. The aforementioned tube is made from cardboard strips, which are unwound from corresponding coils, and then helically wound on a metal shaft having a horizontal axis, and are bonded together to form a structure. tubular self-supporting. Generally, two or three strips of cardboard are used, depending on the desired thickness of the mandrel to be produced. It is also possible to produce mandrels with a single cardboard strip and custom unwind units are used. The cardboard strips overlap partially and by means of an eight-shaped belt wound on two guide rollers, they are wrapped around the shaft and pushed forward, until the tubular cardboard mandrel which advance along the same tree. The belt is also wrapped around the arbor of the mandrel winder to engage the cardboard strips. By means of a special cutting unit, the tubular carton mandrel is cut to a predetermined length which substantially corresponds to the length of the logs to be produced by means of the other machines which are normally referred to as "rewinders". Conventional machines for producing cardboard tubes (or mandrel coils) previously described have a particular disadvantage, namely the inability to increase production beyond a predetermined amount. This implies, in fact, an excessive increase in the speed of the winding rolls, thus leading to the tearing of the paperboard strips due to the resulting excessive tension to which these same strips are subjected. In other words, by increasing the operating speed of the forming group and the development of the propellers on the shaft, the cardboard strips are subjected to a gradually increasing tension. When a threshold speed is exceeded, the tension on the cardboard strips is such that it causes the rupture of these same bands between the winding belt of the forming group and the coils from which the cardboard strips are unwound. .

Therefore, in order to compensate for temporary increases in log production, in most paper mills, additional mandrel winders are placed; said additional mandrel winders normally remain unused or underutilized, with obvious economic and organizational disadvantages. The main object of the present invention is to eliminate or at least reduce drastically the disadvantages mentioned above. This result is obtained, according to the present invention, by a machine of the aforementioned type producing cardboard tubes by means of the helical winding of one or more strips of cardboard partially overlapping one another, characterized in that it comprises a plurality of forming groups which are supported by the same structure and arranged horizontally and vertically in staggered relation to each other, and characterized in that each of said forming groups comprises means for producing a cardboard tube of so that the machine is capable of producing a plurality of cardboard tubes simultaneously. Other features of the present invention, taken alone or in any technically possible combination, are described below: the machine comprises two forming groups so that it is adapted to produce two cardboard tubes simultaneously; each of said forming groups comprises two forming rolls of which one is motorized, that is to say connected to a corresponding motor which controls its rotation with a predetermined angular velocity, and a wound belt to form a shaped figure. "8" on said rollers and on a shaft corresponding to the horizontal axis, the rollers of each forming group being placed on opposite sides with respect to the corresponding shaft, the rollers of each forming group being supported by a plate corresponding metal which, from the opposite side, supports the respective motor and wherein each of said plates has a rear appendage through which it is attached to said structure; said forming groups are a lower forming group and an upper forming group, and they are arranged so that the axes of the rollers of a lower forming group are parallel to a horizontal base of the structure, whereas the axes rolls of an upper forming group are inclined downwards; said forming groups are arranged so that the axes of said rollers are vertical; said forming groups are independent of one another; two dimensions of the machine are smaller than twice the corresponding dimensions of the individual forming groups.

The main advantage deriving from the present invention lies in the possibility of producing a larger number of cardboard tubes without increasing the operating speed of the winding belt which therefore remains within such limits as to minimize the probability of rupture of the cardboard strips.

In addition, a machine according to the present invention is relatively simple to produce, has a size comparable to that of a conventional mandrel winder, or a space considerably less than the size of two conventional mandrel winders, and it has a cost which is relatively low compared to the benefits offered. In addition to this, the operation of a machine for producing cardboard tubes according to the present invention does not require special training. These and other advantages and features of the present invention will emerge more clearly from the following description together with the accompanying drawings given by way of a practical example of the invention, but not taken into consideration in a limiting sense, in which: - Figure 1 is a schematic front view of a machine for producing cardboard tubes according to a first embodiment of the present invention with certain parts not shown to better illustrate the other parts; - Figure 2 is a schematic side view of the mandrel winder of Figure 1; FIG. 3 is an exploded schematic view of the mandrel winder shown in FIG. 1 and FIG. 2; - Figure 4 is a schematic front view of a mandrel winder according to another embodiment of the present invention; Figure 5 is a schematic side view of the mandrel winder shown in Figure 4; FIG. 6 is a schematic top plan view of the mandrel winder shown in FIG. 4 and FIG. 5, with some parts not shown to further illustrate other parts. Reduced to its basic structure and with reference to the example shown in FIGS. 1 to 3, a machine for producing cardboard tubes or mandrel winders according to the present invention comprises two forming groups or units (1, 2). independent (independent) placed (placed) on the same support structure (S). Each of said forming units (1, 2) comprises: two rollers (1a, 1b; 2a, 2b), one of which (1b, 2b) is motorized, that is to say connected to a motor or gearmotor (1m, 2m) corresponding which determines its rotation with a predetermined angular velocity; and a belt (1c, 2c) wound to form the number "8" on said rollers (1a, 1b; 2a, 2b) and on a corresponding shaft (1d, 2d) having a horizontal axis. The rollers of each forming group are placed on opposite sides with respect to the corresponding shaft. The rollers (1a, 1b, 2a, 2b) of each forming unit (1, 2) are supported by a corresponding metal plate (1 e, 2e) which, on the opposite side (rear side), supports the geared motor (1m 2m) respectively. Each of said plates (1 e; 2e) has a rear appendage (1f, 2f) through which it is attached to an inner vertical wall (S1) of the structure (S). According to a known operating procedure, each of said belts (1c; 2c) engages one or more (for example, two) pre-glued strips of cardboard (not shown in the drawings) forcing them to wrap and move forward on the respective shaft (1d; 2d) producing a tube, formed by helical cardboard strips, which advances along the shaft axis with a predetermined speed by the speed of the motorized rollers (1b; 2b). Downstream of each of the shafts (1d; 2d) is placed a corresponding cutting unit (not shown in the drawings) which crosses the cardboard tube transversely to a predetermined length. In the example of FIG. 1, FIG. 2 and FIG. 3, the forming groups (1, 2), vertically and horizontally offset with respect to one another, are arranged so that the axes (1g, 1h) rollers (1a, 1b) of the lower group (1) are parallel to the base (S2) of the structure (S) which is horizontal, while the axes (2g, 2h) of the rollers (2a, 2b) of the upper group (2) are inclined downwards. The angle of inclination of the axes (2g, 2h) of the rollers (2a, 2b) of the upper group (2) is, for example, between 5 ° and 20 ° relative to the horizontal plane. Said angle of inclination is equal to 10 ° in the examples shown in the figure. The same inclinations concern the plates (1 e, 2e) above. In fact, the rear surface (10f) of the appendix (1f), through which the plate (1e) of the forming group (1) is fixed to the wall (S1) of the structure (S), is vertical, while the homologous surface (20f) of the appendix (2f) of the upper forming unit (2) is inclined. This embodiment represents an example of possible connection of the forming groups (1) and (2) to the structure (S) in order to obtain the planned orientation of the axes of the rollers (1a, 1b) and (2a, 2b ).

Since the forming groups (1, 2) are positioned in the structure (S) both horizontally and vertically staggered, and the upper forming unit (2) is inclined as previously described, the height (H ) and the length (L) of the structure (S) are reduced, while allowing the simultaneous production of two tubes (one in the lower group 1 and the other in the upper group 2) and the tube produced by a group n does not interfere with the components of the other group (in particular, with reference to the example shown in FIGS. 1 to 3, the cardboard tube produced by the lower group 1 does not interfere with the components of the higher group 2 ). In the example shown in Figures 1 to 3, the shafts (1d, 2d) of the two forming groups are parallel to each other and oriented along the length (L) of the structure (S). Figures 4 to 6 show another embodiment of the present invention. In these figures, the reference numbers have the meaning described above with reference to the first example. According to the example shown in FIG. 4, FIG. 5 and FIG. 6, the forming groups (1, 2) are vertically and horizontally offset in staggered rows and are arranged with all the axes (1g, 1h, 2g, 2h ) relative rollers (1a, 1b, 2a, 2b) oriented vertically, that is to say with the plates (1 e; 2e) related thereto, oriented horizontally. The trees (ld; 2d) are parallel to each other and are horizontal. The upper forming unit (2) is supported by a horizontal shelf (S3) of the structure (S), while the lower forming unit (1) is supported by the lower base (S2) of the same structure ( S). In particular, the plates (1 e, 2e) are parallel to each other, as shown in Figure 6, and are oriented diagonally with respect to the rear wall (S1) of the structure (S). The fact of providing forming groups (1, 2) makes it possible to reduce the depth (P) of the structure (S) while allowing the simultaneous production of two tubes (one in the lower group 1 and the other in the group superior 2) avoiding that the tube produced by one group interferes with the devices of the other group. According to the present invention, the same structure (S) contains two independent forming groups (1, 2) and a machine which can produce two cardboard tubes simultaneously, has been realized. Although each of the forming groups (1, 2) operates at a speed below the maximum speed permitted by the characteristics of the used paperboard strips (to avoid the disadvantages typical of mandrel winders when used at high speed), the hourly output of the machine is quite superior. For example, using two identical forming groups, if each group operates at 75% of its nominal capacity, the total hourly production is equal to 150% of the output of each group. In addition, the arrangement of the forming groups (1, 2) is such that the overall size of the machine is less than the sum of the dimensions of two individual traditional machines. With reference to the symbols used in the drawings, according to the examples shown in FIG. 1 and in FIG. 2: L = 2b, a <H <2a, c <P <2c; whereas, according to the examples of Figure 4, Figure 5 and Figure 6: P = c, a <L <2a, H = 2b. In other words, in each of the two illustrated examples, the two dimensions of the machine (H and P in the example of Figure 1 and Figure 2; L and P in the example of Figure 4, Figure 5 and Figure 6) are smaller than twice the corresponding dimensions of the individual forming groups. In the two examples described above, the forming groups (1, 2) are positioned relative to one another so as to be vertically and horizontally staggered, and so that the trajectory followed by a tube in cardboard forming on the shaft of a forming group does not interfere with the devices or components of the other forming group. The two forming groups can be fed, for example, with a machine having the characteristics described in document EP 1 545 867, the content of which is referred to for a more detailed description. In practice, the details of execution may vary in any equivalent manner as regards the individual elements described and illustrated and their arrangement, without departing from the scope of the adopted solution and thus remaining in the limits of protection granted to the present invention.

Claims (7)

REVENDICATIONS1. A machine for producing cardboard tubes through the helical winding of one or more paperboard strips partially overlapping each other, characterized in that it comprises a plurality of forming groups which are supported by a same structure (S) and arranged horizontally and vertically staggered with respect to each other, and characterized in that each of said forming groups (1, 2) comprises means for producing a cardboard tube so that the machine is capable of producing a plurality of cardboard tubes simultaneously. 2. Machine according to claim 1, characterized in that it comprises two forming groups (1, 2) so that it is adapted to produce two cardboard tubes simultaneously. 3. Machine according to claim 1 or 2, characterized in that each of said forming groups comprises two forming rollers (1a, 1b, 2a, 2b) of which one (1b, 2b) is motorized, that is to say said connected to a corresponding motor (1m; 2m) which controls its rotation with a predetermined angular velocity, and a belt (1c, 2c) wound to form an "8" shaped figure on said rollers (1a, 1b) , 2a, 2b) and on a shaft (1d, 2d) corresponding to the horizontal axis, the rollers of each forming group being placed on opposite sides with respect to the corresponding shaft, the rollers (1a, 1b, 2a) , 2b) of each forming group (1, 2) being supported by a corresponding metal plate (1 e; 2e) which, from the opposite side, supports the respective motor (1m, 2m) and in which each of said plates (1, 2m) 1 e; 2e) has a rear appendage (1f, 2f) through which it is attached to said structure (S). 4. Machine according to claim 3, characterized in that said forming groups are a lower forming group (1) and an upper forming group (2), and they are arranged so that the axes (1g, 1h) of rollers (1a, 1b) of a lower forming group (1) are parallel to a horizontal base (S2) of the structure (S), while the axes (2g, 2h) of the rollers (2a, 2b) d an upper forming group (2) are inclined downwards. 5. Machine according to claim 3, characterized in that said forming groups are arranged so that the axes (1g, 1h, 2g, 2h) of said rollers (1a, 1b, 2a, 2b) are vertical. Machine according to one or more of the preceding claims, characterized in that said forming groups are independent of one another. Machine according to one or more of the preceding claims, characterized in that two dimensions of the machine are smaller than twice the corresponding dimensions of the individual forming units.