EP2463415A2

EP2463415A2 - Method of production of spinning rotor for an open-end spinning device and such spinning rotor

Info

Publication number: EP2463415A2
Application number: EP11190520A
Authority: EP
Inventors: Jirí Klimes; Milos Mládek; Josef Ludvícek; Frantisek Kríz
Original assignee: Rieter CZ sro
Current assignee: Rieter CZ sro
Priority date: 2010-12-10
Filing date: 2011-11-24
Publication date: 2012-06-13
Also published as: CZ2010921A3

Abstract

Production of a spinning rotor (1) for an open-end spinning machine, at which the spinning cup (11) and the rotor shaft (12) are produced separately, where a semi-product of a body of the spinning cup (11) with allowance for finishing is produced, the finishing of this body is performed, next to this the rotor shaft (12) with a central threaded opening (121) in the face on the side designated for connection with the spinning cup (11) and with allowance for further finishing of its outer surfaces is produced, heat treatment and finishing of the shape of this shaft (12) are performed, at the same time the size of diameter of central cylindrical opening (118) in the body of the spinning cup (11) and size of diameter of corresponding cylindrical section (122) of the rotor shaft (12) are mutually created in specified tolerances. Further, the spinning cup (11) and rotor shaft (12) are at first separately dynamically balanced, after then the spinning cup (11) is installed through the central opening (118) on the corresponding cylindrical section (122) of rotor shaft (12), then both sections are mutually secured by screwing-in the safety screw (3) into a central threaded opening (121) in the face of rotor shaft (12), at the same time the tolerance in size of diameter of the central cylindrical opening (118) in a body of the spinning cup (11) and of diameter of the respective cylindrical section (122) of the rotor shaft (12) are within the range of transition fit.

Description

Technical field

The invention relates to the method of production of spinning rotor for an open-end spinning machine, at which the spinning cup and the rotor driving shaft are produced separately, where a semi-product of a body of the spinning cup with finish allowances is produced, the finishing of this body is performed, next to this the rotor driving shaft with a central threaded opening in the face on the side designated for connection with the spinning cup and with allowances for further finishing of its outer surfaces is produced, heat treatment and finishing of the shape of this shaft are performed, at the same time the size of diameter of central cylindrical opening in the body of the spinning cup and size of diameter of respective cylindrical section of the rotor driving shaft are mutually created in specified tolerances.
The invention also relates to the spinning rotor of an open-end spinning machine comprising the spinning cup and rotor driving shaft, whose co-axial connection is created by a cylindrical opening in the hub of the spinning cup and the outer cylindrical surface of the rotor driving shaft and whose mutual attachment is performed by a safety screw and a thread of threaded opening in axis of the rotor driving shaft, whwreas the rotor driving shaft is provided with means for its rotatable mounting with respect to the body of the spinning device and means for coupling with the rotary drive.

Background art

Spinning rotor at common embodiments of open-end spinning devices is created of a spinning cup, which is arranged at the end of the rotor driving shaft with which it creates one integral unit.
At one large group of spinning devices the driving shaft is mounted in wedge gaps performed between one after another arranged pairs of rotatablymounted supporting discs. The drive of the shaft is mediated through the driving belt, by which the shaft is partially embraced usually in its centre section between the pairs of supporting discs.
At the second large group of spinning devices the driving shaft is mounted in a double-row ball bearing with a great spacing of ball races, whereas the inner bearing races are usually created directly in cylindrical surface of the driving shaft, which is heat treated and finished in a corresponding manner. The drive of the driving shaft also in this embodiment is mediated through the driving belt, which nevertheless acts on the shaft in vicinity of its end being reverse from the spinning cup.
At both mentioned types of spinning devices the spinning rotor is a two-piece one, at the same time the spinning cup with the driving shaft is connected in a fixed manner, mostly by a pressed interference fit. Also in cases when there is additionally used e.g. the screw joint, where the rotor cup to the driving shaft is moreover attached in axis of the shaft by means of a screw, the stiffness of the joint is realised by means of an interference of a hub of the spinning cup and the rotor driving shaft. The requirement for absolute operational stiffness of the joint is given by the working mode of the device, especially by a high rotation speed of the spinning rotor, which at modern machines amounts to more than 100000 min^-1, at the same time production method of the spinning rotor requires that this is perfectly dynamically balanced.
DE 4020518 A1 proposes a two-piece rotor, whose driving shaft in vicinity of the end designated for positioning of a spinning cup is provided with a wider flat collar, which is welded to the shaft, or it is forged with the shaft as one piece and similarly, a section of the shaft between the collar and the adjacent end of shaft creates a faying surface for mounting of the fitted opening of a hub of the spinning cup. After pressing-in this surface abuts with its face to the collar, after which it is axially secured towards the shaft by means of a spring washer. It is advantageous that for example one type of the shaft may be used for various types of spinning cups. After assembly, the spinning rotor is being balanced.
At the solution according to CZ 289599 B6 the spinning cup is fixed on a cylindrical surface of an adapter which is arranged in cavity of bearing shaft of the spinning rotor and which is at its end opposite from the spinning cup connected with axle. The bearing shaft is mounted in a form of aerostatic bearing in the body of the device, while the adapter in vicinity of the spinning cup is in the body mounted by means of grease-lubricated radial sliding bearing with a great play. Mutual mounting of the spinning cup and adapter seems to be insufficiently strong, the whole arrangement is very complicated and probably requires balancing of the unit spinning cup - adapter - bearing shaft.
Also at the spinning devices whose spinning rotor towards the body of the device is mounted by means of magnetic fit arrangement, there exists solution according to DE 10022736 A1 , where the spinning cup with rotor shaft is connected by means of a face clamp, which serves as a centring means between the shaft and spinning cup. Magnet of magnetic mounting positioned in vicinity of the spinning cup is inserted in a face of the clamp being opposite to the spinning cup and the spinning cup, clamp and rotor shaft are mutually screwed together with a screw arranged in axis of the shaft. Nevertheless this solution is not feasible for the above mentioned two big structural groups of spinning devices.
It is apparent that in case of wear or other damage both of the spinning cup or rotor shaft, it is necessary to replace the whole rotor. In most cases the reason for such replacement is wear of rotor shaft either through contact of surface of the shaft with supporting discs at the first group of the device, or wear of the ball bearing and thus ball races performed in the rotor shaft at the second group of the above mentioned spinning devices. Especially wear of bearing races represents a frequent reason for replacement of the spinning rotor as a whole, which has a negative impact on economy in operation of open-end spinning machines of this embodiment.
The goal of the invention is to remedy or at least reduce shortcomings of the background art, to provide possibility of independent replacement of the rotor driving shaft with bearing, possibly of the spinning cup, at the same time to create a rigid and reliable connection of the spinning cup and the rotor driving shaft which would enable a safe operation of the spinning device on a long term basis.

Principle of the invention

The goal of the invention has been achieved by the method of production of the spinning rotor for an open-end spinning machine, at which the spinning cup and rotor shaft are produced separately, whose principle consists in that, the spinning cup and rotor shaft are at first separately dynamically balanced, after then the spinning cup is installed through the central opening on the corresponding cylindrical section of rotor shaft, then both sections are mutually secured by screwing-in the safety screw into a central threaded opening in the face of rotor shaft, at the same time the tolerance in size of diameter of the central cylindrical opening in a body of the spinning cup and of diameter of the respective cylindrical section of the rotor shaft are within the range of transition fit.
Once the spinning cup and independent rotor shaft are assembled, the created connected unit is not balanced any more. If one of these parts is damaged, this part can be replaced while the undamaged part may be used, and the assembled unit is already dynamically balanced.
Tolerance in size of diameter of the central cylindrical opening in a body of the spinning cup and of diameter of the respective cylindrical section of the rotor shaft is applied with interference. The realised fitted joint secures the defined mutual position of these parts, at the same time it could be disassembled without applying any extra endeavour.
Before joining, on mating surface of the central cylindrical opening in body of the spinning cup and/or on a mating surface of outer cylindrical surface of rotor shaft the bonding cement is applied. Through this the joint is a fixed one also in a case that the transition fit is performed with radial play.
Before screwing together, on a threaded surface of the safety screw and/or of the threaded opening in rotor shaft the bonding cement is applied, by which the screwed joint is secured.
The goal of the invention has also been achieved through the spinning rotor of an open-end spinning machine whose principle consists in that, the rotor shaft and the spinning cup are formed of independently dynamically balanced bodies, which after assembly represent a dynamically balanced unit. Upon damage of one of the parts of the spinning rotor this arrangement enables to replace this part only and to further use the undamaged part.

Description of the drawing

Exemplary embodiment of the spinning rotor with bearing of the rotor driving shaft according to the invention is schematically represented in figure in a side view with partial axial section.

Examples of embodiment

Spinning rotor 1 for an open-end spinning device comprises two parts, which are the spinning cup 11 and rotor shaft 12 and which are together axially connected in a fixed manner.
The spinning cavity 111 of the spinning cup 11 from the face side is provided with the face opening 112, whereas the greatest diameter of the spinning cavity 111 creates the known collecting groove 113 of fibres. In face of the spinning cavity 111 there is performed countersink 114 which is connected with exterior of the spinning cup 11 by the known ventilation openings 115. In case of spinning rotor designed for a spinning chamber connected to a source of air underpressure, the spinning cup 11 is without ventilation openings 115. In direction of rotation axis of the spinning cup 11 the spinning cavity 111 continues into a short counterbore 116 which is finished with a circumferential protrusion 117. From the back side in the face of the spinning cup 11 towards the protrusion 117 a cylindrical opening 118 is performed.
In the rotor shaft 12 in the face adjacent to the spinning cup 11 there is performed a blind threaded opening 121 and in vicinity of the face there is an outer surface 122 of the rotor shaft 12 fitted with cylindrical opening 118 of the spinning cup 11. The rotor shaft 12 is in a known manner rotatably mounted in the not represented body of the spinning device, at the same time it itself creates the inner part of double-row rolling ball bearing 2. The surface of rotor shaft 12 is in a known manner provided with two in a greater spacing arranged inner circumferential ball races 123, while the outer ball races are performed in a bushing 21 of the bearing 2. The balls 22 are running in cages 23 and the inner space of the bearing 12 is closed with seals 24, while bushing 21 of the bearing 2 is provided with a not represented opening for refilling of the grease. The end 124 of rotor shaft 12 extending from bushing 21 of the bearing 2 on the side opposite from the spinning cup 11 creates a surface for embracement with a not represented driving belt 4.
The tolerances of diameters of the outer cylindrical surface 122 of rotor shaft 12 and of the cylindrical opening 118 in the rear face of the spinning cup 11 create the fitted joint with transition fit. Face of the rotor shaft 12 in an assembled status is leaning against one surface of contact of the circumferential protrusion 117, while to the opposite side of the protrusion 117 there fits the supporting surface of a head of safety screw 3 screwed in the threaded opening 121 in the rotor shaft 12. The fitted joint is secured by means of this screw 3.
Production method of the spinning rotor 1 according to the invention also comprises known steps for production of semi-product of the spinning cup 11, machining of its outer shape, possibly of ventilation openings 115, counterbore 116 and of axial cylindrical opening 118. The diameter of axial cylindrical opening 118 is produced in tolerance specified for transition fit.
After the finish is accomplished, the dynamic balancing of the spinning cup 11 is performed.
The known steps for production of the rotor shaft 12 comprise a rough machining of its outer shape and of threaded opening 121. After then the corresponding heat treatment of produced semi-product and the finishing operations of machining follow, at the same time the diameter of outer cylindrical surface 122 is produced in tolerance specified for transition fit.
Once the finishing operations are accomplished, the dynamic balancing of the rotor shaft 12 is performed.
Further, there follow the known steps of installation of the bushing 21 of bearing 2 on the rotor shaft 12, after which the complete rotor driving shaft, this is rotor shaft 12 with the bearing 2 installed, is prepared for connection with the spinning cup 11.
The diameters of the cylindrical opening 118 in the spinning cup 11 and of the outer cylindrical surface 122 of rotor shaft 12 are measured using respective known measuring instruments.
In case that these diameters are produced with radial play, thus at the outer cylindrical surface 122 of the rotor shaft 12 the area approaching the lower limit in tolerance of the transition fit is utilised, and at the opening 118 in the spinning cup 11 the area approaching the upper limit in tolerance of the transition fit, on the corresponding surfaces a filling bonding cement possibly a special glue is applied. After then, the outer cylindrical surface 122 of the rotor shaft 12 is inserted into the opening 118 in the spinning cup 11 and from the side of the spinning cavity 111 into the threaded opening 121 in the face of the rotor driving shaft 12 the safety screw 3 is screwed and tightened. The safety screw 3 is tightened by a specified tightening torque, and/or the securing bonding cement possibly special glue for threaded joints is applied on the thread. Once the parts are joined and the cure time of filling bonding cement elapses the radial play is eliminated, whereas the restricted shear strength of the cured bonding filling cement does not prevent a subsequent non-destructive disassembly. The filling bonding cement possibly the securing bonding cement features a sufficient strength, which prevents a mutual movement of surfaces joined using this cement. This is a prerequisite for how to preserve a good status of contact surfaces of both parts on a long-term basis.
If the diameters of the opening 118 in the spinning cup 11 and the outer cylindrical surfaces 122 of the rotor shaft 12 are produced with interference, that means at the outer cylindrical surface 122 of the rotor shaft 12 the area approaching the upper limit in tolerance of the transition fit is utilised, and at the opening 118 in the spinning cup 11 the area approaching the lower limit in tolerance of the transition fit, the mentioned parts are connected without using the filling bonding cement. Preferably, before assembly, the spinning cup 11 may be heated to the temperature of 80 to 100°C.
In the production procedure, at operations for finishing the diameter of opening 118 in the spinning cup 11 and outer cylindrical surface 122 of rotor driving shaft 12 the production tolerances may be preferably reduced so that in all cases the transition fit with this reduced tolerances will show the necessary interference.
Possible replacement of one of the parts of the assembly pair spinning cup 11 - rotor shaft 12 is conditioned by the fact, that there is preserved quality of mating surface of the part which will be further operated. This has been achieved through the mentioned structure of safe connection of two surfaces which may be mutually separated without deteriorating damage of the mating surfaces. The disassembly may usually be performed under cold conditions using a puller when exerting a relatively small force with respect to a small interference in mounting. Of course, removal of the spinning cup may further be facilitated through its warming approximately to the temperature of 80 to 100°C and thus practically eliminating the possibility that the mating surfaces are damaged. Further condition is preserving of a dynamic balancing of the assembled assembly pair spinning cup 11 - rotor shaft 12. This is achieved through a separate dynamic balancing of individual parts of the assembly pair spinning cup 11 - rotor shaft 12. It is obvious, that after joining the spinning cup 11 and the driving shaft 12 the system of the assembly pair spinning cup 11 - rotor shaft 12 will not be balanced any more.
Production method of the spinning rotor 1 according to the invention and also the spinning rotor 1 according to the invention in an advantageous manner solves the situation, when during operation of the spinning device wear or other damage of the bearing 2 or the spinning cup 11 of the spinning rotor occurs, whereas the second of these parts remains undamaged. After disassembly from the device the spinning cup 11 may be separated from rotor shaft 12 without damage of the mating surfaces, this is the opening 118 in the spinning cup 11 and the outer cylindrical surface 122 of the rotor shaft 12. Once the mating surfaces are cleaned and diameter of opening or of outer cylindric section of the part which will be further used and of the new part are measured, the above mentioned assembly will be performed.
As the service life of the bearing 2 in operation of the spinning device is usually shorter than the service life of the spinning cup 11, the prolongation of time for utilisation of the spinning cup 11, whose production is expensive, brings a significant economic contribution.

List of referential markings

1: spinning rotor
11: spinning cup
111: spinning cavity
112: face opening (of spinning cavity)
113: collecting groove (of spun fibres)
114: countersink (of inner face (of spinning cavity)
115: ventilation opening
116: counterbore (of spinning cup from side of spinning cavity)
117: circumferential protrusion (in counterbore and opposite cylindrical opening)
118: cylindrical opening (in spinning cup for connection with driving shaft)
12: rotor shaft
121: threaded opening (in face of driving shaft)
122: outer cylindrical surface of driving shaft (for connection with spinning cup)
123: inner ball race
124: end of driving shaft (for embracement by a driving belt)
2: bearing
21: bearing bushing
22: ball
23: cage (of row of balls)
24: bearing seal
3: safety screw (to secure joint of spinning cup with driving shaft)
4: driving belt

Claims

Method of production of spinning rotor (1) for an open-end spinning machine, at which the spinning cup (11) and the rotor shaft (12) are produced separately, where a semi-product of a body of the spinning cup (11) with finish allowances is produced, the finishing of this body is performed, next to this the rotor shaft (12) with a central threaded opening (121) in the face on the side designated for connection with the spinning cup (11) and with allowance for further finishing of its outer surfaces is produced, heat treatment and finishing of the shape of this shaft (12) are performed, at the same time the size of diameter of central cylindrical opening (118) in the body of the spinning cup (11) and size of diameter of corresponding cylindrical section (122) of the rotor shaft (12) are mutually created in specified tolerances, characterised in that, the spinning cup (11) and rotor shaft (12) are at first separately dynamically balanced, after then the spinning cup (11) is installed through the central opening (118) on the corresponding cylindrical section (122) of rotor shaft (12), then both sections are mutually secured by screwing-in the safety screw (3) into a central threaded opening (121) in the face of rotor shaft (12), at the same time the tolerance in size of diameter of the central cylindrical opening (118) in a body of the spinning cup (11) and of diameter of the respective cylindrical section (122) of the rotor shaft (12) are within the range of transition fit.
Method of production according to the claim 1, characterised in that, the tolerance in size of diameter of the central cylindrical opening (118) in a body of the spinning cup (11) and of diameter of the respective cylindrical section (122) of the rotor shaft (12) is applied with interference.
Method of production according to the claim 1, characterised in that, before joining, on mating surface of the central cylindrical opening (118) in body of the spinning cup (11) and/or on a mating surface of outer cylindrical surface (122) of rotor shaft (12) the bonding cement is applied.
Method of production according to any of the previous claims, characterised in that, before screwing together, on a threaded surface of the safety screw (3) and/or of the threaded opening (121) in rotor shaft (12) the bonding cement is applied.
Spinning rotor (1) of an open-end spinning machine comprising the spinning cup (11) and the rotor shaft (12), whose axial connection is formed of the cylindrical opening (112) in a hub of the spinning cup (11) and the outer cylindrical surface (122) of the rotor shaft (12) and their mutual attachment is performed by the safety screw (3) and a thread of the threaded opening (121) in axis of the rotor shaft (12), while the rotor shaft (12) is provided with means for its rotatable mounting with respect to body of the spinning device and means for coupling with the rotary drive, characterised in that, the rotor shaft (12) and the spinning cup (11) are formed of independently dynamically balanced bodies, which after assembly represent a dynamically balanced unit.