Improved bobbin carrier mandrel in a collection unit for continuous filament yarn

Abstract

 The invention provides an improved bobbin carrier mandrel projecting from a high speed yarn collection unit in continuous filament spinning plants in which the yarn from the spinneret is collected to form wound yarn bobbins, the projecting bobbin carrier part of said mandrel comprising, cooperating coordinatedly, a single external tubular body rigidly connected at its end to a positive drive, at least one tubular element inserted into it, and block means for clamping the support tubes for the wound yarn bobbins.

Description

[0001] This invention relates to a bobbin carrier mandrel projecting from a high speed yarn collection unit in continuous filament spinning plants, its projecting part being in the form of a single load-bearing external tubular body rigidly connected at its end to a positive drive.

[0002] Continuous filament spinning plants for producing synthetic yarns of various kinds are known.

[0003] The yarns leave the spinneret at various speeds, which are always high. The productivity of the production processes and the efficiency of the operational equipment considerably affect market competitiveness.

[0004] As a result, such industries continuously seek improved performance from their machines and equipment, at the lowest possible cost but with an acceptable reliability. The search for improved performance is directed towards incisive improvement of all the constituent components and devices of the machine in all its aspects.

[0005] This also includes improved machine construction, ie by providing a machine of improved quality or greater technological content.

[0006] As is well known to the expert of the art, in continuous filament spinning plants the operational reliability and efficiency of the collection units are of considerable importance. Said units wind the synthetic yarn, originating at high speed from a spinneret, onto bobbins such that it can then be stored for use in subsequent stages of textile manufacture.

[0007] In addition to the machine base, the drive unit and the lubrication and control units, the basic constituent members of the collection unit are a bracket-like support beam, which carries the presser roller and the yarn traversing system, the presser roller itself and the mandrel carrying the bobbins on which the yarn is wound.

[0008] In such a construction the task of greatest severity falls on the mandrel. To perform its task, the mandrel must be able to clamp the tubes of the bobbins on which the yarn is wound, rotate them at the required speed, and finally enable the bobbins to be removed.

[0009] The limits imposed on the mandrel design are of geometrical and kinematic nature.

[0010] To achieve the aforegoing requirements it must firstly be possible to mount the tubes on the mandrel, the mandrel being that rotating member which supports the tubes and rotates them at the appropriate peripheral speed, hence the mandrel must have a free end.

[0011] The outer diameter of the mandrel is determined by the inner diameter of the tubes, which are commercial elements constructed preferably of cardboard or plastic, and hence do not possess high dimensional precision. As the mandrel rotates at high speed it generates dynamic vibration, which compromises the life of the entire collection unit.

[0012] Hence the problem of the mandrel is its mass, in particular the inertial mass related to dynamic vibration.

[0013] To reduce the mass of this mandrel the applicant has both improved its principle of operation by seeking to reduce the mass by means of a different design, and has used light materials. The mandrel described and claimed in the present invention has surprisingly resulted in an improved and more rational geometry of the collection unit together with an improved unit operating performance, to achieve an operational life of the unit which has so far been unachievable.

[0014] The mandrels of currently known collection units operating in continuous filament spinning plants provide precarious operating performance especially at high yarn collection speed. They also have certain drawbacks which make their construction and assembly difficult, leading to a consequent high manufacturing cost. These drawbacks derive mainly from the following aspects:

• use of material of high inertial mass;
• a large number of elements and devices in the expansion system;
• limited bearing life because of substantial dynamic vibration;
• high cost of machining work on the mandrel and on the expansion system;
• high assembly cost because of the mandrel complexity;
• poor facility for inspection and maintenance inside the mandrel;
• low collection speed.

[0015] In view of these defects and drawbacks connected with current mandrels of the state of the art, the primary objective of the present invention is to provide a mandrel arrangement which is improved by virtue of the following constructional and operational aspects:

• use of material of low inertial mass;
• low wear because of reduced and hence uninfluential dynamic vibration;
• low cost of machining work on the mandrel and on the expansion system;
• substantial reduction in assembly cost;
• greater facility for inspection and maintenance inside the mandrel;
• high collection speed.

[0016] An object of the invention is hence to provide a mandrel of simplified construction and perfect operation in particular at high speed, leading to better performance.

[0017] This and further objects are all attained by the improved mandrel of the present invention, wherein the projecting bobbin carrier part comprises, in coordinated cooperation:

• a single external tubular body rigidly connected at its end to a positive drive and carrying a plurality of holes distributed regularly over its circumferential surface to allow the emergence of blocks for clamping the tubes mounted one after another along said external tubular body, this latter being constructed of light composite material such as laminates of steel and aluminium or any other composition, or carbon fibre;
• at least one tubular element inserted into and slidingly coupled to said external tubular body and carrying a plurality of limited inclined surface regions cooperating with the clamping blocks, which emerge or withdraw from the outer surface of the tubular body via the holes distributed uniformly in it with uniform spacing, said tubular element extending axially within the tubular body for a length corresponding at least to the axial length of the entire pack of tubes mounted mutually adjacent on the outside of the projecting mandrel;
• block means of appropriate shape, each arranged to cooperate with an individual hole and with the individual underlying inclined surface in order to clamp the tubes by making them rigid in the manner of a single body with the mandrel, which rotates them at the peripheral speed required to wind the continuous filament spun yarn fed by the overlying spinnerets.

[0018] With reference to the aforesaid the accompanying drawing shows a preferred embodiment, which is neither binding nor limiting in terms of the mutual positioning of the components and the consequent simplifications which may derive therefrom; said embodiment is described hereinafter with reference to the accompanying figures:

Figure 1 is a partly sectional axial schematic view showing the load-bearing external tubular body of the projecting part with an outline indication of the bobbins of wound yarn, said figure also showing the internal tubular element and the base of the machine represented by the collection unit:

Figure 2 is an enlarged schematic axial section through a projecting part of the bobbin carrier mandrel, said figure showing the block means which cooperate with a hole in the tubular body and with the inclined surface of the internal tubular element.

[0019] Those parts not relevant to the invention are omitted from the figures, such as the drive unit, the bracket-like support beam carrying the presser roller and the yarn traversing system together with other parts, as these are known and do not concern the improvement according to the present invention. In the figures, identical parts or those of identical or equivalent function carry the same reference numerals. In these:
1 is the mandrel driver shaft of the known art; 2 is the element or block means arranged to move radially to clamp or unclamp the tubes 5 mounted one after another on the mandrel; 3 is the single external tubular body of the projecting part of the bobbin carrier mandrel, said body being made rigid with the shaft 1 by screw or similar means 10. The tubular body 3 is advantageously of light composite material or carbon fibre; 4 are the inclined surfaces provided in limited regions in the surface of the tubular element 6. Said inclined surfaces 4 are provided at each hole present in the tubular body 3. Each hole and inclined surface 4 cooperate operationally with the block 2 and are distributed uniformly at uniform distance apart in the tubular body and tubular element 3 and 6; 7 is the outline of the bobbins under formation on the mandrel of the collection unit. Said bobbins 7 form on the tubes 5 clamped on the body 3 by the blocks 2, which emerge from the outer surface of the body 3 to press against the inner surface of the tubes 5; 6 is the tubular element inserted into and slidingly coupled to the tubular body 3. Its limited sliding is achieved by the action of the piston 9 of an actuator 12, preferably pneumatic, acting against the end flange of the tubular element 6, which moves on overcoming the thrusting action of the spring 8 acting against the flange at the other end of the tubular element 6; 11 is the frame of the machine represented by the collection unit.

[0020] The operation of the improved bobbin carrier mandrel of the present invention is easily understood.

[0021] The mandrel operation comprises the following operational stages: operating the actuator 12 so that its piston 9 causes a small but sufficient axial movement of the tubular element 6, which compresses the helical spring 8. Because of the provision of the inclined surfaces 4, the blocks 2 move radially into substantial alignment with the outer circumferential surface of the tubular body 3;
mounting the tubes 5 by drawing them one after another along the tubular body 3 forming the load-bearing part of the improved mandrel of the present invention. The tubes 5 can be moved axially along the tubular body 3 because the blocks 2 are able to move radially towards the interior of the tubular body 3, and hence do not form an obstacle;
clamping the mutually adjacent tubes 5 by deactivating the actuator 12, which by retracting its piston 9 allows the spring 8 to exert its thrust action and extend to axially shift the tubular element 6 so that, via the inclined surfaces 4, the blocks 2 emerge radially from the outer surface of the tubular body 3 to clamp the tubes 5, which hence become rigid with the mandrel, ie with the tubular body 3;
activating the collection unit in known manner to wind the yarn onto the tubes 5 rotating at constant peripheral speed.

[0022] By moving the yarn along the lateral surface of the tubes (traversing), bobbins 7 form filled with wound yarn to a predetermined final diameter, as is well known to the expert of the art. When the bobbins 7 reach their final diameter, the mandrel ceases to rotate, in accordance with known operational procedures;

• activating the actuator 12, the piston 9 of which causes the tubular element 6 to undergo a sufficient axial movement to compress the spring 2. Because of the presence of the inclined surfaces 4 the blocks 2 are free to retract and hence unclamp the tubes 5 filled with wound yarn;
• withdrawing and removing the bobbins 7 from the mandrel and mounting new empty tubes 5 one after another on the tubular body 3, which forms the load-bearing part of the improved mandrel according to the present invention;
• then repeating the aforedescribed operating cycle.

[0023] It is apparent that variations, modifications and additions can be made to the details of the improved mandrel of the invention by the expert of the art, without leaving the scope of the present invention.

Claims

1. An improved bobbin carrier mandrel projecting from a high speed yarn collection unit in continuous filament spinning plants, characterised in that the projecting bobbin carrier part comprises, cooperating coordinatedly:

- a single external tubular body rigidly connected at its end to a positive drive and carrying a plurality of holes distributed regularly over its circumferential surface to allow the emergence of blocks for clamping the tubes mounted one after another along said external tubular body;

- at least one tubular element inserted into and slidingly coupled to said external tubular body and carrying a plurality of limited inclined surface regions cooperating with the clamping blocks, which emerge or withdraw from the outer surface of the tubular body via the holes distributed uniformly in it with uniform spacing, said tubular element extending axially within the tubular body for a length corresponding at least to the axial length of the entire pack of tubes mounted mutually adjacent on the outside of the projecting mandrel;

- block means of appropriate shape, each arranged to cooperate with an individual hole and with the individual underlying inclined surface in order to clamp the tubes by making them rigid in the manner of a single body with the mandrel, which rotates them at the peripheral speed required to wind the continuous filament spun yarn fed by the overlying spinnerets.

2. An improved bobbin carrier mandrel projecting from a continuous filament yarn collection unit as claimed in claim 1, characterised in that the external tubular body is of carbon fibre.

3. An improved bobbin carrier mandrel projecting from a continuous filament yarn collection unit as claimed in claim 1, characterised in that the external tubular body is of light composite material such as laminates of steel and aluminium or any other composition of low inertial mass.

Drawing