METHOD FOR MANUFACTURING ROLLS AND ASSOCIATED PRE-SPINNING MACHINE

Description

[0001] The present invention relates to the sector of textile machines for the transformation of ball fiber into a yarn wound on reels.

[0002] In a roving frame, the fiber web obtained from the roving or combing and deposited in cans, is drawn using a drawing device thereby obtaining a roving. In a reel forming device downstream of the drawing device, the roving is wound around small tubes thereby obtaining reels of roving to be sent to the spinning machine.

[0003] The drawing that occurs in the roving frame is highly driven, so that the velocity of the roving downstream of the drawing device is extremely elevated. Furthermore, the roving is subject to oscillations between the drawing device and the device that forms the reels, and is therefore subject to possible breakages. In particular, it is noted that the greatest number of roving breakages occur during the final step of forming the reels. It is evident that the roving breakage, during the step of winding the reel results in a machine stoppage and a consequent slowdown in production. Today, in order to reduce the number of breakages, action is taken in reducing the roving frame production velocity, thereby accepting a certain slowdown in production. Patent document JP S62 85037 A discloses a method of forming reels on a roving frame according to the preamble of claim 1 and a corresponding roving frame according to the preamble of claim 12.

[0004] The object of the present invention is that of providing a method of forming reels and a relative roving frame that reduces roving breakages during the step of winding the reel without compromising the roving frame production velocity.

[0005] This object is achieved by a method of forming reels according to claim 1 and a relative roving frame according to claim 12. The dependent claims describe additional advantageous embodiments.

[0006] The features and advantages of the method and of the roving frame according to this invention will be apparent from the description below, given by way of non-limiting example, according to the figures in the accompanying drawings, wherein: Figure 1 shows a roving frame according to a preferred embodiment of the present invention; Figure 2 shows an enlargement of the roving frame of Figure 1 highlighting the perforated platform wherethrough the rovings exiting the drawing device move from the upper area to the lower area of the roving frame; Figure 3 shows a schematic cross-section view of a portion of the roving frame of Figure 1 highlighting the perforated platform wherethrough the rovings exiting the drawing device move from the upper area to the lower area of the roving frame; the Figures from 4 to 7 show a control scheme for the roving torsion parameter as a function of the reel forming percentage, in various embodiments.

[0007] With reference to the figures in the attached drawings, the numeral 1 has been used overall to indicate a roving frame of a spinning line.

[0008] Typically, upstream of the roving frame 1, a drawframe is arranged that produces a drawn fiber web that is then fed to the roving frame 1. Said frame 1 processes the web and produces a roving that is wound onto appropriate small tubes in order to form reels that are intended to be transported to a spinning machine, downstream of the roving frame 1, for further processing.

[0009] The roving frame 1 has a storage region 200 located to the rear of the body of the machine 2. The web, as provided by the drawer, wound and conserved in cans 4, is deposited within the storage region 200. Also arranged within said storage region 200 is a creel 6 consisting of a frame provided with rollers 8 having a prevalent extension along a longitudinal direction X, generally having a hexagonal section and typically being motorized, arranged above the cans 4.

[0010] The web supplied from the cans 4 is located above the rollers 8 and fed to the roving frame 1.

[0011] The roving frame 1 comprises a machine body 2 that supports a drawing device 10. The drawing device 10 is formed from pairs of superimposed drawing rollers 11, engaged under pressure and having peripheral speeds of rotation that increase from upstream to downstream, so as to progressively draw the web that passes between the coupled drawing rollers 11. In particular, the drawing device 10 comprises motorized lower rollers 111, for example in the number of three or four, wherein each thereof extends in the longitudinal direction X along the frame 1. Each lower roller cooperates with a plurality of separate upper, idling rollers 112, generally supported, in pairs, by pressure arms 113. Preferably, the pressure arms 113 are pushed pneumatically so as to ensure the pressure coupling between the lower roller 111 and the upper rollers 112. In one embodiment, the drawing device 10 is provided with a support band that is in contact with at least one drawing roller 11 in order to guide the rotation thereof. The drawing device 10 processes the fiber web and produces a roving that must subsequently be wound onto appropriate small tubes for reel forming.

[0012] Downstream of the drawing device 10, the machine body 2 comprises a platform 20 having an extension along the longitudinal direction X for the entire length of the frame 1. The platform 20 defines above an upper region of the frame 1 and below a lower region of the frame 1.

[0013] The platform 20 comprises a flat perforated platform 21 wherethrough the rovings exiting the drawing device 10 move from the upper area of the frame 1 to the lower area of the frame 1. The platform 20 in fact houses a plurality of necks 22 that define the passage opening for the rovings that are channeled towards a respective flyer 30. The necks 22, projecting from the platform 21, are organized into two longitudinal rows that are longitudinally displaced therebetween.

[0014] The frame 1 comprises, below the platform 20, a plurality of winding devices for winding the individual rovings onto the respective small tubes thereby forming the reels. The winding devices are flyers 30 that are arranged within the lower region of the frame 1, in particular below each neck 22. The flyers 30 are supported by the platform 20.

[0015] Each flyer 30 is adapted to be rotated about a relative flyer axis Z. The flyers 30 are placed in rotation by means of an electric flyer motor.

[0016] The machine body 2 furthermore comprises a carriage 40, arranged within the region below the frame 1, carrying a plurality of spindles 42 whereonto small tubes are inserted for reel forming. The spindles 42 are arranged coaxially below the respective flyer 30.

[0017] The carriage 40 is vertically translatable with an alternating motion for reel forming, by means of a first electric carriage motor.

[0018] Furthermore, the carriage 40 is horizontally translatable and / or rotatable for the operations, by means of a second electric carriage motor, of lifting completed reels and loading empty small tubes.

[0019] The spindles 42, aligned along the longitudinal direction X, are also movable in rotation coaxially with the vanes 30, by means of an electric spindle motor.

[0020] The flyers 30 are provided with forming means 31 that are adapted to keep the roving attached to the small tube inserted onto the relevant spindle 42 or attached to the reel while forming it.

[0021] In use, the web N passes through the drawing device 10 and leaves it in the form of a roving S that then enters into the respective neck 22 and, by means of the same, passes from the upper area of the frame 1 to the lower area of the frame 1. Here the roving, again by means of the neck 22, enters into the respective flyer 30 and exits therefrom from the lower extremity at the formation means 31. The carriage 40 is moved with an alternating vertical motion, in such a way that the roving is wound onto the small tube inserted onto the spindle 42, and forms a reel B. Once reel forming has been completed said reels are removed and transported, either automatically or manually, to the spinning machine for subsequent processing.

[0022] The frame 1 comprises an electronic control unit that manages the velocity of the electric motors, and therefore the velocity of the flyers 30, the spindles 42, the drawing device 10 and the roving torsion.

[0023] The roving frame production velocity is defined by the velocity of the drawing device 10.

[0024] The roving torsion is a fundamental element insofar as it makes it possible to confer the necessary cohesion to the web bundle in order to obtain the values of resistance required by the subsequent spinning machine processing. The torsion is obtained in rotating the web bundle parallel to the axis thereof. In this way the more external fibers assume a helical arrangement. The internal fibers also assume a helical arrangement but with a slope that little by little decreases towards the center of the bundle. This arrangement confers radial pressure to the fibers so that drawing is avoided that is uncontrolled and unwanted before entering the spinning machine drawing unit, but without compromising the spinning machine drawing unit drawing step. Increasing the torsion therefore improves the resistance of the roving, but the greater the torsion the more difficult it is to draw the roving. Furthermore, increased torsion results in a reduction in production velocity and a consequent reduction in the productivity of the machine.

[0025] The torsion is applied to the roving in the frame 1 exiting the drawing device 10, during the flyer-spindle unit entering step, in particular at the entrance to the neck 22.

[0026] The roving torsion is defined as the ration between the flyer-spindle unit rotation velocity and the drawing device 10 velocity, and is conventionally indicated as torsions per meter or torsions per inch.

[0027] The object of the present invention is a method of forming reels on a roving frame 1 for processing of a fiber web and forming a roving wound on reels. The roving frame 1 is provided with a drawing device 10 of the fiber web for forming the roving and a flyer-spindle unit for winding said roving into reels. The method provides applying, to a bundle of fibers exiting the drawing device 10 and entering the flyer-spindle unit an initial torsion (Ti) at the start of reel forming. The method is characterized in that it passes from the initial torsion Ti to the final torsion Tf while providing at least one step of increasing the roving torsion. For example, the method provides for arriving at the end of forming with a final torsion Tf which is greater than the initial torsion Ti.

[0028] The method of forming reels, according to the present invention, therefore provides for varying the roving torsion in reel forming step. In particular, the method of forming reels, according to the present invention, provides to increase the roving torsion in reel forming step. Advantageously, this solution makes it possible to increase the resistance of the roving whilst reducing those breakages that are typical of the final reel forming step, without compromising the productivity of the machine.

[0029] In the graph of Figure 4, the variation in torsion is indicated with ΔT, that is to say the variation between the initial torsion Ti, i.e., at the start of reel forming, and the final torsion value Tf, i.e., at the end of reel forming.

[0030] The forming method provides to increase the roving torsion by 10%, preferably 5%, even more preferably 3%. This range of increase in torsion increments the resistance of the yarn without rendering it too rigid and therefore unsuitable for subsequent processing.

[0031] Preferably, the forming method provides to increase the roving tension in increasing the velocity of the flyer-spindle unit in relation to the velocity of the drawing device 10 during the reel forming step.

[0032] Preferably, the forming method provides to increase the roving tension in increasing the velocity of the flyer-spindle unit whilst maintaining unaltered the velocity of the drawing device 10 during the reel forming step.

[0033] In the flyer-spindle unit the flyer 30 turns at a flyer velocity that is different than the velocity of rotation of the spindle 42, of the spindle velocity. In particular, the spindle velocity is greater than that of the flyer Therefore, increasing the flyer-spindle unit velocity significantly increases the flyer velocity whilst maintaining unaltered the ratio between the spindle velocity and the flyer velocity. In other words, this signifies increasing the velocity of the spindle in proportionately increasing the velocity of the flyer

[0034] Reel forming is measured by using the diameter thereof, which passes from an initial diameter, equal to the diameter of the small tube, to the final diameter, equal to the final diameter of the formed reel.

[0035] Figures from 4 to 7 show some control schemes for the roving torsion parameter as a function of the reel forming percentage.

[0036] In the example of Figure 4, the torsion increases in a linear manner, from the initial value Ti to the final value Tf.

[0037] In the example of Figure 5, the torsion exhibits a stepped progression, that is to say that is maintains the initial value Ti up and until a torsion-raising point P, wherein it is increased directly up to the final value Tf.

[0038] In the example of Figure 6 the torsion exhibits a double step increase, that is to say that is maintains the initial value Ti up and until a first torsion-raising point P wherein it is increased up to an intermediate torsion value, maintaining such intermediate value up and until a second torsion-raising point P wherein it is increased up to the final value Tf.

[0039] Preferably, the increase in the torsion value is provided for during the final reel forming step, that is to say that from 50% of reel forming onwards. Preferably, the increase in the torsion value is envisaged from 60% to 70% of reel forming.

[0040] In one exemplary embodiment, shown in Figure 7, an increase in the torsion value is envisaged up and until the final reel forming step wherein a reduction in torsion is envisaged down to a final value Tf, that is equal to or less than the initial value Ti.

[0041] The object of the present invention is also a roving frame 1 for processing a fiber web and forming a roving wound on reels, comprising: a drawing device 10 of the fiber web for forming the roving; a flyer-spindle unit for winding said roving into reels; management means adapted to control the torsion of the roving exiting the drawing device 10 and entering the flyer-spindle unit according to the forming method described above.

[0042] Innovatively, the reel forming method according to the present invention makes it possible to reduce roving breakages during the step of winding the reel without compromising the roving frame production velocity.

[0043] It is clear that a person skilled in the art, in order to satisfy current needs, could make modifications to the roving frame and method described above, which modifications are all contained within the scope of protection as defined in the following claims.

Claims

1. A method of forming reels on a roving frame (1) for processing a fiber web and forming a roving wound on reels, said roving frame being provided with a drawing device (10) of the fiber web for forming the roving and a flyer-spindle unit for winding said roving into reels, wherein the method provides applying, to the fibers exiting the drawing device (10) and entering the flyer-spindle unit, an initial torsion (Ti) at the start of reel forming and a final torsion (Tf) at the end of reel forming, characterized in that it passes from the initial torsion (Ti) to the final torsion (Tf) while providing at least one step of increasing the torsion.

2. A method of forming reels according to claim 1, wherein there is provided to increase said initial torsion (Ti) in reel forming step up to reaching a final torsion (Tf) at reel forming ending which is greater than the initial torsion (Ti).

3. A method of forming reels according to claim 1 or 2, wherein said flyer-spindle unit has a unit rotation speed and the drawing device (10) has a drawing speed, and wherein the increase of the initial torsion (Ti) is obtained by increasing the flyer-spindle unit rotation speed with respect to the drawing speed.

4. A method of forming reels according to claim 3, wherein the increase of the initial torsion (Ti) is obtained by increasing the flyer-spindle unit rotation speed while keeping unaltered the drawing speed.

5. A method of forming reels according to any one of the preceding claims, wherein said flyer-spindle unit comprises a flap (30) having a flat rotation speed and a spindle (40) having a spindle rotation speed, and the increase of the initial torsion (Ti) is obtained by increasing the flap rotation speed while keeping unaltered the flap rotation speed and spindle rotation speed ratio.

6. A method of forming reels according to any one of the preceding claims, wherein said initial torsion (Ti) is increased by 10%, preferably by 5%, even more preferably by 3%.

7. A method of forming reels according to any one of the preceding claims, wherein said initial torsion (Ti) increases in a linear manner.

8. A method of forming reels according to any one of claims 1 to 6, wherein said initial torsion (Ti) remains constant up to a torsion raising point (P) at which it is directly increased to reach the final torsion (Tf).

9. A method of forming reels according to claim 8, wherein said torsion raising point (P) is provided in the final reel forming step.

10. A method of forming reels according to claim 9, wherein said torsion raising point (P) is provided at between 60% and 70% of the reel forming step.

11. A method of forming reels according to any one of claims 1 to 6, wherein said initial torsion (Ti) has at least one torsion raising point (P) at which it increases.

12. A roving frame (1) for processing a fiber web and forming a roving wound on reels, comprising: - a drawing device (10) of the fiber web for forming the roving; - a flyer-spindle unit for winding said roving into reels; - characterized by management means adapted to control a torsion of the fibers exiting the drawing device (10) and entering the flyer-spindle unit according to the reel forming method according to any one of the preceding claims.