Field of the invention

[0001] The object of the present invention is a comber of a spinning preparation line.

[0002] In a spinning preparation line, after the initial stages of opening and cleaning the fiber, a carding process by carding machines is envisaged, after which the fiber is presented in the form of sliver.

[0003] After possible processing on a lap winder, wherein several separate slivers are joined to obtain a lap, the sliver or lap is combed by a comber, in order to obtain a web wherein the fibers are highly parallelized and clean.

State of the art

[0004] The basic combing operations, which in the most recent machines are carried out at a rate of 450 500 strokes per minute, are:

- intermittent feeding of the lap;

- combing, by means of a rotary comb, of the head of the incoming fringe, with the nipper closed;

- overlapping and joining of the head of the fringe to the web already combed in the previous cycle, suitably retracted, by means of detaching rollers during the reverse rotation thereof;

- combing of the tail of the fringe by means of a straight comb on the nipper, with the nipper open;

- advancing the combed fringe by the detaching rollers during the forward rotation thereof.

[0005] The detaching rollers therefore have an alternating rotary motion. The moving members of the detaching rollers, which, starting from an electric motor, control the detaching rollers and allow the alternating movement thereof, are one of the most problematic parts of the design and construction of a comber.

[0006] Such members must in effect withstand intense dynamic stress, as they are subjected to repeated stops and restarts. As the speed of the machine increases, the rotation speed of the detaching rollers, in one direction and in the other, increases proportionally. Dynamic stresses therefore become increasingly more severe.

[0007] These members are moreover very large and account for at least 30% to 40% of the final cost of the comber.

[0008] There are patent documents that illustrate solutions for combers with continuous rotary movement of the detaching rollers. Consider, for example, the document EP-A1-1553219.

[0009] Nevertheless, the Applicant, by experimentally replicating the solution illustrated in the document EP-A1-1553219, has been able to ascertain that the combing result is not satisfactory from the perspective of the web quality obtained.

[0010] Finally, there are comber solutions wherein the detaching rollers are controlled by an electronically controlled electric motor to obtain alternating rotary motion; in this case, the complicated mechanical moving members of the detaching rollers mentioned above are not necessary.

[0011] However, such solutions have significant drawbacks, mainly related to energy consumption, the heating of the electric motors, the service life of such motors and the response of the control of the movement.

Object of the invention

[0012] The object of the present invention is to create a comber with detaching rollers having, during normal combing operations, continuous rotary motion and thus able to ensure a satisfactory level of quality of the combed web.

[0013] Such object is achieved by a comber made according to claim 1. The dependent claims describe further advantageous embodiments of the invention.

Brief description of the figures

[0014] The features and advantages of the comber according to the present invention will be apparent from the description given below, provided by way of non-limiting example, in accordance with the accompanying figures, wherein:

- figures 1 to 10 illustrate a diagram of a comber according to the present invention, in successive processing steps; and

- figure 11 contains a graph explaining the operation of the comber according to the invention.

Detailed description of the invention

[0015] A comber according to the present invention comprises a fixed frame and a nipper 4, supported by the fixed frame.

[0016] The nipper 4 comprises a lower jaw 6, an upper jaw 8 and a straight comb 10, usually attached to the lower jaw 6.

[0017] Moreover, the nipper 4 comprises a feed roller 12, which is rotatable intermittently on command, supported by the lower jaw 6.

[0018] The comber further comprises, downstream of the nipper 4, a first pair of detaching rollers 20, comprising an upper detaching roller 20a and a lower detaching roller 20b, generally pressure-coupled with the upper detaching roller 20a and pulled in rotation thereby.

[0019] Between said detaching rollers 20a, 20b, on the side of the nipper 4, there is an inlet port 22 wherein the nipper 4 carries the section of sliver that has been released by the feed roller 12. On the other side, there is an outlet port 24.

[0020] The comber further comprises a second pair 30 of detaching rollers, downstream of the first pair 20; said second pair 30 comprises an upper detaching roller 30a and a lower detaching roller 30b, generally pressure-coupled with the upper detaching roller 20a and pulled in rotation thereby.

[0021] Between said detaching rollers 30a, 30b, on the nipper 4 side, there is an inlet port 32 and, on the opposite side, an outlet port 34.

[0022] Moreover, preferably, the comber comprises a fixed table 36 placed between the first detaching rollers 20a, 20b and the second detaching rollers 30a, 30b; preferably, said table 36 has a bearing surface 38, generally flat, placed between the port of the first detaching rollers 20a, 20b and the port of the second detaching rollers 30a, 30b.

[0023] The comber further comprises a circular comb 40, generally placed under the nipper 4, having a continuous rotary motion, at constant or variable speed, always in the same direction.

[0024] The comber is provided with one or more electric motors and a plurality of transmission members suitable for transferring the motion from said at least one electric motor to the components mentioned above.

[0025] In particular, the nipper has a forward and return movement and the jaws have an opening and closing movement with a predefined working speed Vp .

[0026] In particular, the nipper 4 has alternating forward and return movement between a forward limit position, wherein the jaws 6, 8 are proximal to the detaching rollers 20a, 20b, and a retracted limit position, wherein said jaws 20a, 20b are distal from said detaching rollers 20a, 20b.

[0027] At the same time, the jaws 6, 8 have an alternating opening and closing motion, while the feed roller 12 has an intermittent rotary motion that allows the release of a section of sliver from the nipper.

[0028] The detaching rollers 20a, 20b of the first pair 20 have a continuous rotary motion (at constant or variable speed, but without inversion) , each with an angular rotation speed Wc in one rotation direction to detach a fringe of fiber from the section of sliver in the inlet port 22.

[0029] Similarly, the detaching rollers 30a, 30b of the second pair 30 have continuous rotary motion synchronized with that of the cylinders 20a, 20b of the first pair 20.

[0030] The comber further comprises a support 50 located downstream of the second pair 30 of detaching rollers 30a, 30b, suitable to receive the fringes of sliver fed in succession from said detaching rollers 30a, 30b of the second pair 30.

[0031] Preferably, the support 50 is permeable to air and is operatively connected to a suction device so as to obtain a suction air flow through the surface, suitable to hold said fringes .

[0032] Moreover, the support 50 is movable so that, by advancing, it allows the partial overlapping of the fringes which lie in succession thereon.

[0033] For example, the support 50 is an air-permeable belt, arranged along a closed path.

[0034] Along a support section of said closed path, the belt 50 runs over a rigid base 52, connected to a suction duct 54 of the suction device.

[0035] Preferably, moreover, along said closed path, the belt 50 cooperates with belt rollers 56, 58 that define said closed path and with a pair 60 of pulling rollers.

[0036] For example, said pair 60 of pulling rollers comprise an upper pulling roller 60a, preferably outside the closed path, and a lower pulling roller 60b preferably inside the closed path .

[0037] The belt 50 is compressed between the pulling rollers 60a, 60b, at least one of which is motorized and the other idle, to obtain the forward motion.

[0038] Preferably, the comber further comprises a pair 70 of compacting rollers suitable to compact the web formed by the overlapping of the fringes on the belt 50.

[0039] In particular, said pair 70 of compacting rollers comprises an upper compacting roller 70a and a lower compacting roller 70b, pressure-coupled.

[0040] Preferably, said compacting rollers 70a, 70b also serve as pulling rollers 60a, 60b. [0041] Preferably, moreover, the comber comprises a pair 80 of output rollers, located downstream of the compacting rollers 70a, 70b; for example, said pair 80 of output rollers comprise an upper output roller 80a and a lower output roller 80b, pressure-coupled, at least one of which is motorized and the other idle.

[0042] For clarity of presentation of the comber' s operation, it is recognized that initially the nipper 4 is in the forward limit position and the jaws 6, 8 are open (figure 1) . The feed roller 12 is stopped and a first fringe U1 has been detached by the detaching rollers 20a, 20b, which have continuous rotary motion in the direction of extraction from the nipper; while said first fringe U1 advances, the outgoing tail is combed by the straight comb 10.

[0043] Subsequently, the nipper 4 begins to retract, the straight comb 10 has finished combing the first fringe U1 and the continuous rotation of the detaching rollers 20a, 20b carries it towards the belt 50 or towards the second detaching rollers 30a, 30b (figure 2) . The feed roller 12 rotates and brings a new section of sliver out of the lower jaw 6.

[0044] Subsequently, the nipper 4 continues to retract, as does the rotation of the feed roller 12, which brings more and more sliver out of the lower jaw 6. The continuous rotation of the detaching rollers 20a, 20b causes the first fringe U1 to advance ( figure 3 ) .

[0045] Subsequently, the nipper 4 reaches the limit retracted position, in which it is closed, as the lower jaw 6 and the upper j aw 8 are engaged with each other (figure 4) . The circular comb 40, which is equipped with continuous rotary motion, is in an angular position so as to begin combing the head of a second fringe U2. The feed roller 12 is once again stopped, while the first fringe U1 continues to advance due to the continuous rotation of the detaching rollers 20a, 20b. [0046] Subsequently, while the nipper 4 is stationary, the circular comb 40 continues the combing of the head of the second fringe U2 (figures 5, 6 and 7) . The first fringe U1 continues to advance due to the continuous rotation of the detaching rollers 20a, 20b.

[0047] Subsequently, the nipper 4 resumes its forward movement, and the circular comb 40 has finished combing the head of the second fringe U2, which is offered to the detaching rollers 20a, 20b (figure 8) . The first fringe U1 is meanwhile passed to the second detaching rollers 30a, 30b, while a fringe U0 preceding the first fringe U1 leaves the second detaching rollers 30a, 30b and is carried on the belt 50, resting thereon.

[0048] Subsequently, the nipper 4 continues to advance towards the limit forward position, while the second fringe U2 engages the first detaching rollers 20a, 20b. The first fringe Ul, on the other hand, advances under the action of the second detaching rollers 30a, 30b.

[0049] Finally, the nipper 4 reaches the forward limit position (figure 10), wherein, in the inlet port 22, a new fringe is detached from the sliver by the first detaching rollers 20a, 20b.

[0050] With the succession of the aforesaid steps, the first fringe Ul leaves the second detaching rollers 30a, 30b and is carried on the belt 50 so as to overlap with its head the tail of the previous fringe U0, as the previous fringe U0 is advanced by virtue of the movement of the belt 50.

[0051] A continuous web is thus formed on the belt 50, in which the head of a subsequent fringe overlaps the tail of a previous fringe .

[0052] The web thus formed passes between said compacting rollers 70a, 70b, in order to regularize the thickness.

[0053] According to the invention, the comber comprises management means 100 suitable for adjusting the rotation speed Wc of at least one of said detaching rollers 20a, 20b as a function of the working speed Vp of the nipper 4, said management means 100 being configured or programmed so that said rotation speed Wc, as a function of the working speed Vp of the nipper 4, follows a predefined law.

[0054] In other words, the management means 100 are suitable to adjust the rotation speed of the detaching rollers 20a, 20b (generally, rpm) as a function of the working speed of the machine, i.e. as a function of the number of strokes or cycles in the unit of time (generally, strokes/minute) of the nipper.

[0055] Said management means 100 are configured or programmed so that the rotation speed of the detaching rollers 20a, 20b, as a function of the working speed of the machine, follows a predefined law that is not linearly proportional.

[0056] In the graph of figure 11, the abscissa shows the working speed Vp of the nipper, expressed as strokes/minute, and the ordinate shows the ratio R between the rotation speed Wc of the detaching rollers (rpm) and the working speed Vp of the nipper.

[0057] The dashed line T indicates the trend of such ratio R for a traditional machine; such trend T is parallel to the axis of the abscissas, because as the working speed of a traditional comber increases, the rotation speed of the detaching rollers increases in proportion linearly. Consequently, the ratio is constant (in the example of the graph in figure 11, equal to 3) .

[0058] The continuous line C indicates the trend, according to one embodiment, of the ratio for the comber according to the invention; the trend of the ratio is increasing, for example it may be approximated with a linear function in sections, with the increase of the working speed Vp of the machine, up to values between 2 and 2.5, for example equal to 2.25.

[0059] For example, according to the graph in figure 11, at an initial working speed of VpO, i.e. 100 strokes/minute, the rotation speed WcO of the detaching rollers is, for example, equal to about 50 rpm; for an intermediate working speed of Vpl (Vpl>Vp0), e.g. equal to 500 strokes/minute, Wcl is, for example, equal to about 750 rpm. Between VpO and Vpl, the trend of the ratio R=Wc/Vp is approximated by an increasing linear function having a first predefined slope SI.

[0060] At a limit working speed Vpf (Vpf>Vpl>Vp0 ) , e.g. 700 strokes/minute, Wcf is, for example, about 1680 rpm. Between Vpl and Vpf, the trend of the ratio R=Wc/Vp is approximated by an increasing linear function having a second predefined slope S2 greater than the first slope SI (S2>S1) .

[0061] Collectively, therefore, the trend of the rotation speed Wc of the detaching rollers has an increasing trend that is not proportional (for example, with a linear ratio of R=Wc/Vp or linear in sections or non-linear) with respect to the working speed Vp .

[0062] In other words, according to the invention, as the working speed Vp of the machine increases, the rotation speed Wc of the detaching rollers increases more than proportionally, according to a predefined law.

[0063] The Applicant has in effect found that by increasing the rotation speed of the detaching rollers more than proportionally, and in particular more than linearly, as the working speed of the machine increases, the quality of the web obtained is greatly improved.

[0064] At the same time, the Applicant has found that while maintaining a proportionality between the working speed of the machine and the rotation speed of the detaching rollers, as is the case with the combers of the prior art, the quality of the web is unsatisfactory and at times the fringe tends to wrap itself around the same detaching rollers.

[0065] Said management means 100 operate both during the operation of the comber at full speed, imposing the desired rotation speed Wc on the detaching rollers 20a and 20b, and during the transitional phase necessary to bring the comber up to the working speed Vp, starting, for example, from a stationary machine condition.

[0066] During the transitional phase, said management means 100 operate in the sense that, as the working speed Vp of the comber increases, they impose on the detaching rollers 20a, 20b a rotation speed Wc that is a function of the working speed Vp, but that increases more than proportionally.

[0067] Innovatively, the comber according to the present invention overcomes the drawbacks mentioned with reference to the prior art.

[0068] In particular, advantageously, the comber, according to the present invention, is very compact, since the cumbersome members for the alternating motion of the detaching rollers according to the prior art are no longer necessary.

[0069] Advantageously, moreover, there are no members subject to heavy dynamic stresses, as were the control members of the detaching rollers of the prior art.

[0070] It is apparent that one skilled in the art, in order to meet contingent needs, may make changes to the comber described above, all contained within the scope of protection as defined by the following claims.