"Combing machine with variable speed circular comb"

[0001] The present invention relates to a combing machine of a spinning line for processing fibre to obtain a yarn.

[0002] On a fibre processing line for the production of yarn, after the initial phases of opening and cleaning the fibre, carding is performed by carding machines, after which the fibre appears in the form of a web.

[0003] After processing, if any, on a lap-winder, in which various separate webs are combined to form a lap, the web or lap is combed by a combing machine, so as to obtain a web in which the fibres have been rendered highly clean and parallel.

[0004] Combing is performed by circular combs, which are used to comb the heads of the tufts of the lap, and by straight nipper combs, used to comb the tails of the same tufts of the lap. The combed tufts are fed to the tearing rollers, situated downstream of the combs, so that the edges overlap; the continuous web formed proceeds for subsequent processing.

[0005] The circular comb is provided with a continuous rotatory movement, synchronised with the alternate movement of the nipper, so as not to interfere structurally with it.

[0006] It is therefore extremely advantageous for the circular comb to have a variable rotation speed, so that rotation is slower when the nipper is near the tearing rollers (and the circular comb is therefore idle) and faster when the circular comb combs the fibre (and the nipper is therefore distant from the tearing rollers) and when the tearing rollers move the already previously combed tuft backwards for overlapping with the new one. By so doing, timing is optimised, reducing the dynamic severity of the movements, in particular of the tearing rollers, and paying particular attention in any case to avoiding structural interference between the circular comb and the nipper.

[0007] Solutions of circular combs with variable speed rotatory movements exist. Some examples are described in EP 936292 and EP 754253.

[0008] However, the prior solutions present various drawbacks, for example, caused by the need to make specific mechanical components, such as gears with asymmetric profiles, or by the limited reliability of independent motorisation for the circular comb which, in the case of malfunction, may give rise to extremely harmful impact.

[0009] The purpose of the present invention is to satisfy the aforementioned requirements and overcome the drawbacks of the prior solutions. [0010] Such purpose is achieved by a combing machine according to claim 1 below.

[0011] The characteristics and advantages of the combing machine according to the present invention will be evident from the following description, made by way of a non-limiting example, with reference to the attached drawings, wherein:

[0012] - figure 1 shows the diagram of a combing machine, in a forward position of the nipper;

[0013] - figure 2 shows the diagram of figure 2, in a rearward position of the nipper;

[0014] - figure 3 shows a kinematic diagram of a combing machine according to the present invention, according to one embodiment;

[0015] - figure .4 schematically illustrates a transmission device of the combing machine in figure 3 (one stage transmission device) ;

[0016] - figures 5 and 6 show the trends of the laws of motion of the transmission device in figure 4;

[0017] - figure 7 shows a kinematic diagram of a combing machine according to the present invention, according to a further embodiment;

[0018] - figures 8a and 8b schematically illustrate a transmission device of the combing machine in figure 7 (two stage transmission device) ; [0019] - figures 9 and 10 show the trends of the laws of motion of the transmission device in figure 8;

[0020] - figures 11a and lib illustrate a transmission device of the combing machine in figure 7 (two stage transmission device) , according to a further embodiment;

[0021] - figures 12 and 13 show the progress of the laws of motion of the transmission device in figure 11;

[0022] - figure 14 shows a transmission device of the combing machine, according to yet a further embodiment; and

[0023] - figure 15 is a ground view from above of the transmission device in figure 14.

[0024] A combing machine according to the invention comprises a fixed frame 2, a nipper 4 and a circular comb 20.

[0025] The nipper 4 comprises a lower jaw 6 and an upper jaw 8; the nipper 4 further comprises a straight comb 10, suitable for combing the tail of the tuft.

[0026] In addition, the nipper 4 comprises a rotating feed roller 12, supported by the lower jaw 6.

[0027] Downstream of the nipper 4 are pairs of tearing rollers 14, 16, having an alternate rotatory movement.

[0028] The nipper 4 has an alternate back and forth movement; in a forward position, the nipper occupies a processing zone and the jaws 6, 8 are next to the tearing rollers 14, 16 and closed, so as to nip the web being processed; in a rearward position of the nipper, the jaws 6, 8 are distal from the tearing rollers 14, 16 and open.

[0029] The circular comb 6 is joined in rotation to a main shaft 18 and has a continuous rotatory movement. The circular comb 20 operates on the head of the tuft of the web when it transits immediately upstream of the tearing rollers, in other words through the processing zone.

[0030] The rotatory movement of the circular comb 20 is synchronised with the alternate movement of the nipper 4, so that when the nipper is in the forward position, in other words in the processing zone immediately upstream of the tearing rollers, the comb 20 is inactive, that is to say outside the processing zone; when the nipper is in the rearward position, in which the jaws do not occupy the processing zone, the comb is in said processing zone and performs combing of the head of the tuft.

[0031] The combing machine further comprises an electric motor 21 and a kinematism 22 for the transmission of the rotatory movement from the motor 21 to the main shaft 18.

[0032] The kinematism 22 comprises a transmission device 30 able to vary a uniform circular movement in input into a non-uniform circular movement in output, transmitting it to the main shaft 18.

[0033] According to one embodiment the transmission device 30 comprises a main body 32, for example in the shape of a disc, joined on one side to a driven transmission shaft 19, which identifies a fixed driven transmission axis 34 and which is joined to the main shaft 18.

[0034] The transmission body 32 is further engaged, on the other side, with a motor transmission shaft 36, which identifies a motor transmission axis 38, also fixed. The motor transmission shaft 36 receives the rotatory movement from the electric motor 21.

[0035] The motor transmission axis 38 is distanced from the driven transmission axis 34; the distance between said transmission axes is defined as eccentricity.

[0036] According to one embodiment the transmission body 32 has a groove 39 on the side of the motor transmission shaft 36, preferably rectilinear, for example having a diametral extension.

[0037] For example, the transmission device 30 further comprises a crank 40, connected to one end, joined in rotation to the motor transmission shaft 36; at the other end, the crank 40 comprises a pin 42, inserted in the groove 39 so as to slide, having a pin axis 44.

[0038] The distance between the pin axis 44 and the motor transmission axis 38 is defined as the crank distance.

[0039] According to one embodiment the pin is mounted loose on the crank and thereby, during use, rolls in the groove like a roller; according to a further embodiment, the pin is mounted on the crank so as to be fixed and bears a skate, free to rotate around the pin and slide in the groove, like a sliding skate.

[0040] It has been seen that for a constant rotation speed of the motor transmission shaft 36, the rotation speed of the driven transmission shaft 19 is variable.

[0041] Figure 5 shows the trend of the rotation speed of the motor transmission shaft 36 (constant and equal in the graph to 500 revs/min) and the corresponding rotation speed of the driven transmission shaft 19 (variable from a minimum of 468 revs/min to a maximum of 536 revs/min) , for a predetermined eccentricity (of 10 millimetres) and a predetermined crank length (150 millimetres) .

[0042] Figure 6 shows the acceleration trend of the motor transmission shaft 36 (constant and equal to 0) and the corresponding variable acceleration of the driven transmission shaft 19, for the same parameters as above.

[0043] Advantageously, using the transmission device a variable speed circular movement of the circular comb is achieved; in particular, by appropriately selecting the eccentricity and crank length values during the design phase, the desired values of maximum and minimum speeds of the driven transmission shaft may be achieved.

[0044] According to a further embodiment (figure 7) the transmission device 30 comprises a plurality of transmission bodies, for example two transmission bodies 32', 32" in cascade.

[0045] In the embodiment with two transmission bodies the first body 32' comprises a motor transmission shaft 36' , a crank 40' with a pin 42' sliding in a groove 39' and an output transmission shaft; the first body 32' has a first eccentricity and a first crank length.

[0046] The second body 32" comprises a motor transmission shaft 36", coaxial and coinciding with the transmission shaft in output of the first body 32' , a crank 40" with a pin 42" sliding in a groove 39" and the driven transmission shaft 19, joined in rotation to the main shaft 18; the second body 32" has a second eccentricity and a second crank length.

[0047] According to a first embodiment variation the grooves 39' , 39" of the bodies 32' , 32" are aligned for the same angular position of the two bodies 32*, 32" (figures 8a and 8b) .

[0048] Figure 9 shows the trend of the rotation speed of the motor transmission shaft 36' of the first body 32' (constant and equal, in the graph, to 500 revs/min) , the corresponding rotation speed of the motor transmission shaft 36" of the second body 32" and the corresponding rotation speed of the driven transmission shaft 19 (variable from a minimum of 415 revs/min to a maximum of 610 revs/min), for predetermined eccentricities (10 millimetres for the first body and 5 millimetres for the second body) and predetermined crank lengths (150 millimetres for the first body and 100 millimetres for the second body) .

[0049] Figure 10 shows the acceleration trend of the motor transmission shaft 36' of the first body 32' (constant and equal to 0) , the corresponding acceleration of the motor transmission shaft 36" of the second body 32" and the corresponding acceleration of the driven transmission shaft 19, for the same parameters of eccentricity and crank length as above .

[0050] In a further embodiment of a two stage transmission device (figures 11a and lib) the groove 39' of the first body 32' is angularly dephased from the groove 39" of the second body 32", in the same angular position.

[0051] Figure 12 shows the trend of the rotation speed of the motor transmission shaft 36' of the first body 32' (constant and equal to 500 strokes/min) , the corresponding rotation speed of the motor transmission shaft 36" of the second body 32" and the corresponding rotation speed of the driven transmission shaft 19, for a phase shift of 45° between the grooves 39', 39", for predetermined eccentricities and predetermined crank lengths. The phase shift of the maximum and minimum speed values, and therefore the ability to regulate the angular position of the acceleration interval may be noted.

[0052] Figure 13 shows the acceleration trend of the motor transmission shaft 36' of the first body 32' (constant and equal to 0) , the corresponding acceleration of the motor transmission shaft 36" of the second body 32" and the corresponding acceleration of the driven transmission shaft 19, for a phase shift of 45° between the grooves 39' , 39", at the same eccentricity and crank lengths parameters as above.

[0053] According to a further embodiment the transmission device 30 comprises an intermittor, in particular of the flat type, comprising a first body or motor body 52, joined in rotation to the motor shaft 36, and a second body or driven body 54, joined in rotation to the driven shaft 19, meshing permanently with the motor body 52.

[0054] The term "intermittent drive" indicates herein a transmission wherein the motor body is composed of one or more cams and the driven body is composed of a plate bearing a series of rollers which form a shaped coupling with the cam at all times.

[0055] For example, one of the two bodies 52, 54, preferably the motor body 52, comprises a first half-body 52a and a second half-body 52b positioned in axial succession.

[0056] For example, the two half-bodies 52a, 52b are made in one piece; according to one embodiment variation, the two half bodies 52a, 52b are made in two separate pieces, touching each other or axially distanced from each other.

[0057] Preferably, each half-body 52a, 52b is made in the shape of a plate, defined by a front side 56 and an opposite rear side, orthogonal to the driven axis 38, and a thickness surface 60.

[0058] The motor body 52 is shaped so as to form a plurality of lobes connected with each other; for example, each half-body 52a, 52b is shaped so as to present a plurality of lobes 62, connected to each other; for example, each half-body 52a, 52b is trilobate.

[0059] Preferably, in addition, the first half-body 52a is phase shifted in relation to the second half-body 52b, so that a lobe 62 of the first half-body 52a is positioned between two successive lobes 62 of the second half-body 52b, for example on the centreline between them.

[0060] The other of the two bodies 52, 54, preferably the driven body 54, comprises a plurality of angularly spaced rollers, at least one of which is engaged with the other body 52, to ensure the transmission of movement to the driven shaft 19. Preferably, at least one pair of rollers is always in contact with the motor body, to facilitate regularity of the movement.

[0061] In particular, the motor body 52 is shaped so as to ensure a variable speed circular movement to the driven body 54, such as a continuous or intermittent circular movement, in other words having intervals during which the rotation speed of the driven body is nil despite the speed of the motor body.

[0062] Preferably, a first group of rollers 64 is suitable for engaging with the first half-body 52a of the motor body 52 and a second group of rollers 66 is suitable for engaging with the second half-body 52b of the motor body 52, in that the first group of rollers 64 is positioned in axial succession in relation to the second group of rollers .

[0063] For example, the driven body 54 comprises a disc 68 which the rollers 64 of the first group of rollers 64 project from the front of and the rollers 66 of the second group of rollers 66 project from the back of; the rollers 64 of the first group of rollers 64 are phase shifted in relation to the rollers 66 of the second group of rollers 66.

[0064] Preferably, in addition, the rollers of the driven body 54 are mounted so as to rotate loosely and facilitate engagement with the motor body 52.

[0065] Preferably, in addition, the driven body 54 comprises a front plate 70 and a rear plate 72, respectively to support the rollers 64 of the first group and the rollers 66 of the second group, so as to form a closed package-like driven body 54.

[0066] Innovatively, the transmission device of the combing machine according to the present invention makes it possible to optimise synchronisation of the movement of the nipper and rotation of the circular comb, using a highly reliable mechanical system with a precise movement without any mechanical components which are complex to manufacture .

[0067] Advantageously, in addition, during the design phase, the one stage transmission device enables the minimum and maximum speeds of the circular comb to be defined, merely by varying the eccentricity and crank length, or the breadth of the acceleration or deceleration interval.

[0068] According to a further advantageous aspect the two stage transmission device enables the minimum and maximum speeds and the breadth of the acceleration or deceleration interval to be defined independently.

[0069] According to yet a further advantageous aspect the transmission device, in the two stage phase shift embodiment, makes it possible to adequately design the angular position of the acceleration and deceleration interval .

[0070] According to yet a further advantageous aspect the transmission device with intermittent drive is particularly simple to produce and highly reliable.

[0071] Advantageously, in addition, the transmission device with intermittent drive is able to support very high loads, in that it is structurally very robust.

[0072] According to a further advantageous aspect the transmission device with intermittent drive shows limited wear, due mainly to the absence of rubbing between the motor body and the driven body, unlike a gear mechanism for example .

[0073] According to yet a further advantageous aspect the transmission device with intermittent drive makes it possible to substantially eliminate the play between the motor body and the driven body, especially in the embodiment with half-bodies.

[0074] Advantageously, in addition, the transmission device with intermittent drive makes it possible to create highly complex laws of motion, unlike transmissions with gears, thanks to the desired profiling of the motor body.

[0075] It is clear that a person skilled in the art may make modifications to the transmission device described above so as to satisfy contingent requirements while remaining within the sphere of protection of the following claims.