Title of Invention	CLAMPING DEVICE
Abstract	The present invention relates to a clamping device (4) for clamping threads on a spindle of a spinning or twisting machine, the clamping device (4) being arranged on a top spindle part (1) and comprising a fixed clamping element (5) and an axially displaceable clamping element (6) which can be pressed by a spring force against the fixed clamping element (5), wherein centrifugal-force elements (9) can bias the displaceable clamping element (6) counter to the spring force by means of a force which spaces the displaceable clamping element (6) apart from the fixed clamping element (5) in the axial direction such that a clamping nip (16) forms between these elements and wherein the clamping device (4) has holders which serve for accommodating and guiding the centrifugal-force elements (9), the holders for the centrifugal-force elements (9) being arranged on that side of the clamping device (4) which is located opposite the clamping nip (16), and a compression spring (8) being arranged between the holders and the clamping nip (16).

Title of Invention

CLAMPING DEVICE

Abstract

The present invention relates to a clamping device (4) for clamping threads on a spindle of a spinning or twisting machine, the clamping device (4) being arranged on a top spindle part (1) and comprising a fixed clamping element (5) and an axially displaceable clamping element (6) which can be pressed by a spring force against the fixed clamping element (5), wherein centrifugal-force elements (9) can bias the displaceable clamping element (6) counter to the spring force by means of a force which spaces the displaceable clamping element (6) apart from the fixed clamping element (5) in the axial direction such that a clamping nip (16) forms between these elements and wherein the clamping device (4) has holders which serve for accommodating and guiding the centrifugal-force elements (9), the holders for the centrifugal-force elements (9) being arranged on that side of the clamping device (4) which is located opposite the clamping nip (16), and a compression spring (8) being arranged between the holders and the clamping nip (16).

Full Text	FORM 2 THE PATENT ACT 197 0 (39 of 1970) & The Patents Rules, 2003 COMPLETE SPECIFICATION See Section 10, and rule 13 1. TITLE OF INVENTION CLAMPING DEVICE 2. APPLICANT(S) a) Name b) Nationality C) Address OERLIKON ACCOTEX TEXPARTS GMBH GERM/AN Company MARIA-MERIAN-STRASSE 8, D-70736 FELLBACH, GERMANY 3. PREAMBLE TO THE DESCRIPTION The following specification particularly describes the invention and the manner in which it is to be performed : - The invention relates to a clamping device for threads on a spindle of a spinning or twisting machine according to the preamble of claim 1. A clamping device is known from DE 196 28 826 Al, which has a clamping element rigidly attached to a wharve of a spindle and a clamping element which can be displaced axially with respect to the longitudinal axis of the spindle. The clamping elements are pressed against one another by a compression spring, which is supported on the displaceable clamping element and the wharve, so a clamping gap forms between the clamping elements. To open the clamping gap by the displacement of the displaceable clamping element against the force of the compression spring, the displaceable clamping element has an inwardly inclined conical annular face, which, with the fixed clamping element, limits an annular chamber, in which movable centrifugal force elements are arranged. When a limit rotational speed is exceeded, the force applied by the centrifugal force bodies on the displaceable clamping element is greater than the spring force, and this leads to a movement of the displaceable clamping element in the axial direction and therefore to the opening of the clamping gap. When the limit rotational speed is fallen below, the clamping device goes into its clamping position. In the clamping position, in which the end faces of the two clamping elements are pressed against one another, a shoulder arranged on the end face of the displaceable clamping element engages in a corresponding annular groove on the end face of the fixed clamping element to seal off the annular chamber relative to the clamping gap. It proves to be disadvantageous in this clamping device that, despite the shoulder, a penetration of thread residues into the annular chamber may occur. This is promoted in that the annular groove is configured as an undercut, into which thread residues to be clamped, fibre material or the like can be drawn. Thread residues already located in the annular groove can arrive via the shoulder into the annular chamber by means of further clamping processes, so the centrifuging off of the thread residue during doffing is prevented and the annular chamber becomes soiled. This soiling oi the annular chamber results in the centrifugal force elements arranged therein being at least partially blocked and this leads to an impairment of the functionality of the clamping device, in particular owing to the imbalance occurring. Furthermore, fibre material or fibre residues already located in the annular groove are compressed therein by the spring force and can no longer be centrifuged off when the clamping gap is opened. Thus, with the increasing soiling of the annular groove, the clamping effect which can be applied to the thread is reduced and this further impairs the functionality of the clamping device. The invention is based on the object of developing the clamping device in such a way that a substantially interruption-free continuous operation of the clamping device is ensured. This object is achieved according to the invention by a clamping device with the features of claim 1. Advantageous configurations of a clamping device of this type are the subject of the sub-claims. The configuration according to the invention of the clamping device provides that the receivers for the centrifugal force elements are arranged on the side of the clamping device opposing the clamping gap, a compression spring being arranged between the receivers and the clamping gap. Owing to the spatial spacing of the receivers being used for the arrangement and guidance of the centrifugal bodies from the clamping gap, the susceptibility to soiling of the clamping device according to the invention is reduced. The penetration of thread residues, fibre material or the like via the clamping gap into the receivers of the centrifugal force elements is substantially avoided in this manner, so the occurrence of blockages oi the centrifugal force elements owing to thread residues or the like penetrating into the guides is prevented. In addition, the positioning of the centrifugal force elements spaced apart from the clamping gap also allows the use of the clamping device for rings with a smaller ring diameter which concentrically surround the upper spindle part and, on which, a traveller, which deflects the thread to the tube, circulates. In an advantageous development of the invention, the receivers may be configured as two mutually corresponding half shells extending in the radial direction, which surround the centrifugal force elements. This has the advantage that the centrifugal force elements are forcibly guided because of the positive fit. In contrast to the prior art, in which the guidance of the centrifugal force elements takes place in channels, which are arranged on the lower side of the fixed clamping element and therefore allow a relatively large play, all the centrifugal bodies are always located on a path with the same axial spacing owing to the forced control according to the invention, so imbalances can be avoided. The centrifugal force elements are guided virtually free of play in each position within the receivers and exert the same axial forces on the displaceable clamping element, so the clamping element is prevented from tilting. The closed design of the receivers also prevents the penetration of thread residues or the like, so the risk of impairment of the functionality is further reduced. Advantageously, the receivers may be arranged uniformly distributed over the periphery of the clamping device. This arrangement of the receivers brings about a substantially tilt-free guidance of the displaceable clamping element on the upper spindle part. For this purpose, the receivers may be arranged offset with respect to one another at an angle less than or equal to 180°, in particular at an angle of 90° or 60°. This allows the arrangement of two or more centrifugal force elements distributed over the periphery of the clamping device. A half shell may preferably be arranged in each case on the displaceable clamping element and the respectively corresponding half shell may be arranged on a rigidly arranged base element. The base element is supported on a drive wharve arranged on the upper spindle part and is used by the displaceable clamping element as an abutment. The link-like guide of the centrifugal force elements may be configured in the half shells of the base element or of the displaceable clamping element with a link inclined with respect to the horizontal and the corresponding half shells may be configured with a link substantially parallel to the horizontal, the links being used for the guidance of the centrifugal force elements. The links of the half shells with links substantially parallel to the horizontal mean that the centrifugal force elements can move in these half shells substantially outwardly in the radial direction, while owing to the incline of the links of the corresponding half shell, the centrifugal force elements move the displaceable clamping element in the axial direction to open the clamping gap. In particular, the incline of the links in the displaceable clamping element may be between 10° and 70°, in particular between 15° and 65°. This allows the selection of the spring force which presses the two clamping elements in the clamping position of the clamping device against one another as the counter-force varies depending on the implementation of the incline of the links. Furthermore, the displaceable clamping element may be guided with its half shells in grooves arranged on the outer periphery of the base element. The grooves simplify the assembly during the supply of the displaceable clamping element and ensure the mutually corresponding arrangement of the half shells with respect to one another so that the centrifugal force elements are virtually completely surrounded by the half shells. In addition, a twisting of the displaceable clamping element relative to the base element is prevented by the grooves. In particular, the clamping elements may have complementary webs and recesses on their mutually facing end faces. The clamping effect can thus be increased by a more acute clamping angle between the webs and recesses as well as the enlargement of the thread contact face between the webs and recesses. Furthermore, the lateral surfaces of the clamping elements may be conically configured in the region of the clamping gap, at least in portions. In this manner, the supply of the thread is simplified if the latter is not inserted directly into the clamping gap, but rests on the lateral surface of one of the clamping elements. The conicity of the lateral surface means that the thread may slide into the clamping gap because of the thread tension to ensure, when the spindle is braked, that the thread rests over its supplied length in the clamping gap. The invention will be described in more detail below with the aid of an embodiment shown in the drawings, in which: Fig. 1 shows a perspective partial view of an upper spindle part; Fig. 2 shows a sectional view of a clamping device according to the invention in its clamping position; Fig. 3 shows a sectional view of the clamping device in the opened position; Fig. 4 shows a perspective view of a base element. Fig. 1 shows an upper spindle part 1 of a spindle of a textile machine, in particular a spinning and twisting spindle. The upper spindle part 1 has a shaft made of metal, which is used to receive a tube, shown, on to which a thread is to be wound to form a cop. For this purpose, arranged on the upper spindle part 1 is a spinning ring, not shown, which concentrically surrounds the upper spinning part 1 and on which a traveller circulates, which deflects the thread to the tube and winds it thereon. Arranged on the upper spindle part 1 is a drive wharve 2, by means of which the upper spindle part 1 can be driven during operation of the textile machine. The drive wharve 2 has a thread 3 which is used to fasten a clamping device 4 according to the invention for clamping the thread during doffing of the produced cop. The clamping device 4 is actuated by centrifugal force and may adopt two positions, a clamping position, in which the thread is clamped, and an opened position in which the thread can be supplied or released and centrifuged oii. Fig. 2 shows the clamping device 4 according to the invention in its clamping position, while, in Fig. 3, the clamping device 4 is shown in an opened position. In the clamping position, the end faces of two clamping elements 5, 6 are pressed against one another, while in the opened position, a clamping gap 16 is produced between the two clamping elements 5, 6. The clamping device 4 is multi-part and comprises a fixed clamping element 5 and an axially displaceable clamping element 6 which can be pressed against the fixed clamping element 5, as well as a base element 7, which, in the assembled position of the clamping device 4 is supported on a flange-like step 10 of the drive wharve 2 to fix the clamping device 4 in the axial direction. Furthermore, the clamping device 4 comprises a compression spring 8 as well as a plurality of centrifugal force elements 9, which are in particular designed as balls and are arranged uniformly distributed in the clamping device 4 over the periphery of the upper spindle part 1 offset at an angle to one another. The clamping elements 5, 6, on their mutually facing end faces, have complementary webs and recesses, which engage in one another in the clamping position of the clamping device 4 to exert a greater clamping effect on the thread located in the clamping gap 16. The lateral surfaces 17, 18 of the clamping elements 5, 6 facing the clamping gap 16 are conically configured, in portions. The base element 7 is used to receive and guide the centrifugal force elements 9. For this purpose, the substantially cylindrical base element 7 has a wall 11 coaxial to the longitudinal axis of the upper spindle part 1, which wall is provided with a number of through-bores 12 corresponding to the number of centrifugal force elements 9. Arranged on the side of the wall 11 remote from the drive wharve 2 are half shells 13, which, as shown in Fig. 4, extend, proceeding from the through-bores 12 radially outwardly with respect to the longitudinal axis of the upper spindle part 1. The half shells 13, in this case, adjoin the through-bores 12 in the axial direction. In order to virtually completely surround the centrifugal force elements 9, the displaceable clamping element 6 has half shells 15 corresponding with the half shells 13 and extending in the radial direction. The half shells 13,15 being used to receive the centrifugal force elements 9 are configured corresponding to the form of the spherical centrifugal force elements 9 and adapted to their dimensions. In addition, the wall 11 has grooves 14 extending in the axial direction of the upper spindle part 1, which are arranged adjacent to the half shells 13 on the wall 11. The grooves 14 are used here to position and prevent twisting of the displaceable clamping element 6. For this purpose, the grooves 14 of the base element 7 have a width corresponding to the width of the half shells 15 so the half shells 15 are guided therein. The clamping element 6 is positioned and guided by the grooves 14 relative to the base element 7 in such a way that in the position of the clamping element 4 assembled on the upper spindle part 1, the centrifugal force elements 9 are surrounded by the half shells 13, 15 and outwardly sealed, in that the two corresponding half shells 13, 15 in the position of the clamping device 4 assembled on the upper spindle part 1 form a closed chamber. In this manner, a guidance of the centrifugal force elements 9 is achieved and the centrifugal force elements 9 are protected from soiling from thread residues, fibre material or the like. The guidance of the centrifugal force elements 9 is achieved by a link-like guide. For this purpose, the half shells 15 of the clamping element 6 have a link inclined with respect to the horizontal and the half shells 13 of the base element 7 have a link which extends in the radial direction, in which the spherical centrifugal force elements 9 can move. The angle of the inclined link is preferably between 10° and 70°, in particular 15° to 65°. The compression spring 8 is supported on the base element 7 and on the displaceable clamping element 6 surrounding the base element 7 and presses the latter in the direction of the fixed clamping element 5. The transition between the clamping position and the opened position of the clamping device 4 takes place when a limit rotational speed is exceeded or fallen below during spinning operation. The limit rotational speed corresponds to the rotational speed of the upper spindle part 1, at which the force acting in the axial direction and exerted by the centrifugal force elements 9 on the displaceable clamping element 6 is less than the force acting through friction and the compression spring 8 on the clamping elements 5,6. The exceeding of the limit rotational speed means that the centrifugal force elements 9 are pressed outwardly, with them being forcibly guided within the two half shells 13, 15 by the links. The incline of the links of the half shells 15 of the displaceable clamping element 6 leads to a force running parallel to the longitudinal axis of the upper spindle part 1 from the centrifugal force elements 9 acting on the clamping element 6, which force counteracts the force of the compression spring 8 and is greater in terms of amount. This leads to an axial displacement of the clamping element 6, so the clamping gap 16 is opened. If a doffing process of the tube is due, a ring rail, not shown, is guided downwardly to such an extent that the thread guided by the traveller circulating on the spinning ring is placed in the region of the opened clamping gap 16. In this case, it is not necessary for the thread to be wound with a full revolution around the clamping device 4. When being placed on one of the conical lateral surfaces 17,18 of the clamping elements 5, 6, the thread slides because of the conicity and the thread tension into the clamping gap 16 or the thread is placed directly into the clamping gap 16. The falling below of the limit rotational speed owing to the following braking process leads to a reduction in the centrifugal force, so the centrifugal force elements 9 move inwardly and finally, when the spindle is at a standstill, rest on the surface of the drive wharve 2, as shown in Fig. 2, so no adequate force directed counter to the compression spring 8 is applied to the displaceable clamping element 6. The spring force presses the displaceable clamping element 6 against the fixed clamping element 5, so the clamping gap 16 is closed. The mutually complementary webs and recesses on the end faces of the clamping elements 5, 6 engage in one another and clamp the thread located in the clamping gap 16. The subsequent doffing of the tube brings about the severing of the thread. For this purpose, the webs, which are, for example, trapezoidal or configured as a pointed tooth system, are sharp-edged in configuration, so the severing of the thread is simplified. Once the process of the doffing is completed and the spinning operation has been resumed, on exceeding the limit rotational speed, the clamping gap 16 is opened again and this leads to a centrifuging away of the thread residue located therein, which until then remained in the clamping gap 16. WE CLAIM: 1. Clamping device (4) for threads on a spindle of a spinning or twisting machine, the clamping device (4) being arranged on an upper spindle part (1)/ comprising a fixed clamping element (5) and an axially displaceable clamping element (6) which can be pressed against the fixed clamping element (5) by spring force, the displaceable clamping element (6) being loadable by centrifugal force elements (9) counter to the spring force by a force which spaces the displaceable clamping element (6) in the axial direction apart from the fixed clamping element (5) in such a way that a clamping gap (16) is formed between them and in that the clamping device (4) has receivers being used for the arrangement and guidance of the centrifugal force elements (9), characterised in that the receivers for the centrifugal force elements (9) are arranged on the side of the clamping device (4) opposing the clamping gap (16), a compression spring (8) being arranged between the receivers and the clamping gap (16). 2. Clamping device (4) according to claim 1, characterised in that the receivers are in each case configured as two half shells (13,15) corresponding with one another and extending in the radial direction, which surround the centrifugal force elements (9). 3. Clamping device (4) according to claim 2, characterised in that the half shells (13, 15) are arranged uniformly distributed over the periphery of the clamping device (4). 4. Clamping device (4) according to either of claims 2 or 3, characterised in that in each case a half shell (15) is arranged on the displaceable clamping element (6) and the respectively corresponding half shell (13) is arranged on a rigidly arranged base element (7). 5. Clamping device (4) according to any one of claims 2 to 4, characterised in that the half shells (13, 15) of the base element (7) or of the displaceable clamping element (6) are configured with a link inclined to the horizontal and the corresponding half shells (13,15) are configured with a link substantially parallel to the horizontal, the links being used to guide the centrifugal force elements. 6. Clamping device (4) according to claim 5, characterised in that the incline of the links in the clamping element (6) is between 10° and 70°, in particular between 15° and 65°. 7. Clamping device (4) according to any one of claims 2 to 6, characterised in that the displaceable clamping element (6) is guided with its half shells (15) in grooves (14) arranged on the outer periphery of the base element (7). 8. Clamping device (4) according to any one of claims 1 to 7, characterised in that the clamping elements (5, 6) have complementary webs and recesses on their mutually facing end faces. 9. Clamping device (4) according to any one of claims 1 to 8, characterised in that the lateral surfaces (17, 18) of the clamping elements (5, 6) are conically configured in the region of the clamping gap (16), at least in portions. Dated this 14th day of October 2008. HIRAL CHANDRAKANT JOSHI AGENT FOR OERLIKON ACCOTEX TEXPARTS GMBH

Full Text

FORM 2
THE PATENT ACT 197 0 (39 of 1970)
&
The Patents Rules, 2003 COMPLETE SPECIFICATION See Section 10, and rule 13
1. TITLE OF INVENTION CLAMPING DEVICE

2. APPLICANT(S)
a) Name
b) Nationality C) Address

OERLIKON ACCOTEX TEXPARTS GMBH GERM/AN Company MARIA-MERIAN-STRASSE 8, D-70736 FELLBACH, GERMANY

3. PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner in which it is to be performed : -

The invention relates to a clamping device for threads on a spindle of a spinning or twisting machine according to the preamble of claim 1.
A clamping device is known from DE 196 28 826 Al, which has a clamping element rigidly attached to a wharve of a spindle and a clamping element which can be displaced axially with respect to the longitudinal axis of the spindle. The clamping elements are pressed against one another by a compression spring, which is supported on the displaceable clamping element and the wharve, so a clamping gap forms between the clamping elements. To open the clamping gap by the displacement of the displaceable clamping element against the force of the compression spring, the displaceable clamping element has an inwardly inclined conical annular face, which, with the fixed clamping element, limits an annular chamber, in which movable centrifugal force elements are arranged. When a limit rotational speed is exceeded, the force applied by the centrifugal force bodies on the displaceable clamping element is greater than the spring force, and this leads to a movement of the displaceable clamping element in the axial direction and therefore to the opening of the clamping gap.
When the limit rotational speed is fallen below, the clamping device goes into its clamping position. In the clamping position, in which the end faces of the two clamping elements are pressed against one another, a shoulder arranged on the end face of the displaceable clamping element engages in a corresponding annular groove on the end face of the fixed clamping element to seal off the annular chamber relative to the clamping gap.
It proves to be disadvantageous in this clamping device that, despite the shoulder, a penetration of thread residues into the annular chamber may occur. This is promoted in that the annular groove is configured as an undercut, into which thread residues to be clamped, fibre material or the like can be drawn. Thread residues already located in the annular groove can arrive via the shoulder into the annular chamber by means of further clamping processes, so the centrifuging off of the

thread residue during doffing is prevented and the annular chamber becomes soiled. This soiling oi the annular chamber results in the centrifugal force elements arranged therein being at least partially blocked and this leads to an impairment of the functionality of the clamping device, in particular owing to the imbalance occurring. Furthermore, fibre material or fibre residues already located in the annular groove are compressed therein by the spring force and can no longer be centrifuged off when the clamping gap is opened. Thus, with the increasing soiling of the annular groove, the clamping effect which can be applied to the thread is reduced and this further impairs the functionality of the clamping device.
The invention is based on the object of developing the clamping device in such a way that a substantially interruption-free continuous operation of the clamping device is ensured.
This object is achieved according to the invention by a clamping device with the features of claim 1.
Advantageous configurations of a clamping device of this type are the subject of the sub-claims.
The configuration according to the invention of the clamping device provides that the receivers for the centrifugal force elements are arranged on the side of the clamping device opposing the clamping gap, a compression spring being arranged between the receivers and the clamping gap. Owing to the spatial spacing of the receivers being used for the arrangement and guidance of the centrifugal bodies from the clamping gap, the susceptibility to soiling of the clamping device according to the invention is reduced. The penetration of thread residues, fibre material or the like via the clamping gap into the receivers of the centrifugal force elements is substantially avoided in this manner, so the occurrence of blockages oi the centrifugal force elements owing to thread residues or the like penetrating into the guides is prevented.

In addition, the positioning of the centrifugal force elements spaced apart from the clamping gap also allows the use of the clamping device for rings with a smaller ring diameter which concentrically surround the upper spindle part and, on which, a traveller, which deflects the thread to the tube, circulates.
In an advantageous development of the invention, the receivers may be configured as two mutually corresponding half shells extending in the radial direction, which surround the centrifugal force elements. This has the advantage that the centrifugal force elements are forcibly guided because of the positive fit. In contrast to the prior art, in which the guidance of the centrifugal force elements takes place in channels, which are arranged on the lower side of the fixed clamping element and therefore allow a relatively large play, all the centrifugal bodies are always located on a path with the same axial spacing owing to the forced control according to the invention, so imbalances can be avoided. The centrifugal force elements are guided virtually free of play in each position within the receivers and exert the same axial forces on the displaceable clamping element, so the clamping element is prevented from tilting. The closed design of the receivers also prevents the penetration of thread residues or the like, so the risk of impairment of the functionality is further reduced.
Advantageously, the receivers may be arranged uniformly distributed over the periphery of the clamping device. This arrangement of the receivers brings about a substantially tilt-free guidance of the displaceable clamping element on the upper spindle part. For this purpose, the receivers may be arranged offset with respect to one another at an angle less than or equal to 180°, in particular at an angle of 90° or 60°. This allows the arrangement of two or more centrifugal force elements distributed over the periphery of the clamping device.
A half shell may preferably be arranged in each case on the displaceable clamping element and the respectively corresponding half shell may be arranged on a rigidly arranged base element. The base element is supported on a drive wharve arranged on the upper spindle part and is used by the displaceable clamping element as an

abutment. The link-like guide of the centrifugal force elements may be configured in the half shells of the base element or of the displaceable clamping element with a link inclined with respect to the horizontal and the corresponding half shells may be configured with a link substantially parallel to the horizontal, the links being used for the guidance of the centrifugal force elements. The links of the half shells with links substantially parallel to the horizontal mean that the centrifugal force elements can move in these half shells substantially outwardly in the radial direction, while owing to the incline of the links of the corresponding half shell, the centrifugal force elements move the displaceable clamping element in the axial direction to open the clamping gap.
In particular, the incline of the links in the displaceable clamping element may be between 10° and 70°, in particular between 15° and 65°. This allows the selection of the spring force which presses the two clamping elements in the clamping position of the clamping device against one another as the counter-force varies depending on the implementation of the incline of the links.
Furthermore, the displaceable clamping element may be guided with its half shells in grooves arranged on the outer periphery of the base element. The grooves simplify the assembly during the supply of the displaceable clamping element and ensure the mutually corresponding arrangement of the half shells with respect to one another so that the centrifugal force elements are virtually completely surrounded by the half shells. In addition, a twisting of the displaceable clamping element relative to the base element is prevented by the grooves.
In particular, the clamping elements may have complementary webs and recesses on their mutually facing end faces. The clamping effect can thus be increased by a more acute clamping angle between the webs and recesses as well as the enlargement of the thread contact face between the webs and recesses.

Furthermore, the lateral surfaces of the clamping elements may be conically configured in the region of the clamping gap, at least in portions. In this manner, the supply of the thread is simplified if the latter is not inserted directly into the clamping gap, but rests on the lateral surface of one of the clamping elements. The conicity of the lateral surface means that the thread may slide into the clamping gap because of the thread tension to ensure, when the spindle is braked, that the thread rests over its supplied length in the clamping gap.
The invention will be described in more detail below with the aid of an embodiment shown in the drawings, in which:
Fig. 1 shows a perspective partial view of an upper spindle part;
Fig. 2 shows a sectional view of a clamping device according to the invention in its clamping position;
Fig. 3 shows a sectional view of the clamping device in the opened position;
Fig. 4 shows a perspective view of a base element.
Fig. 1 shows an upper spindle part 1 of a spindle of a textile machine, in particular a spinning and twisting spindle. The upper spindle part 1 has a shaft made of metal, which is used to receive a tube, shown, on to which a thread is to be wound to form a cop. For this purpose, arranged on the upper spindle part 1 is a spinning ring, not shown, which concentrically surrounds the upper spinning part 1 and on which a traveller circulates, which deflects the thread to the tube and winds it thereon. Arranged on the upper spindle part 1 is a drive wharve 2, by means of which the upper spindle part 1 can be driven during operation of the textile machine.
The drive wharve 2 has a thread 3 which is used to fasten a clamping device 4 according to the invention for clamping the thread during doffing of the produced

cop. The clamping device 4 is actuated by centrifugal force and may adopt two positions, a clamping position, in which the thread is clamped, and an opened position in which the thread can be supplied or released and centrifuged oii.
Fig. 2 shows the clamping device 4 according to the invention in its clamping position, while, in Fig. 3, the clamping device 4 is shown in an opened position. In the clamping position, the end faces of two clamping elements 5, 6 are pressed against one another, while in the opened position, a clamping gap 16 is produced between the two clamping elements 5, 6. The clamping device 4 is multi-part and comprises a fixed clamping element 5 and an axially displaceable clamping element 6 which can be pressed against the fixed clamping element 5, as well as a base element 7, which, in the assembled position of the clamping device 4 is supported on a flange-like step 10 of the drive wharve 2 to fix the clamping device 4 in the axial direction.
Furthermore, the clamping device 4 comprises a compression spring 8 as well as a plurality of centrifugal force elements 9, which are in particular designed as balls and are arranged uniformly distributed in the clamping device 4 over the periphery of the upper spindle part 1 offset at an angle to one another. The clamping elements 5, 6, on their mutually facing end faces, have complementary webs and recesses, which engage in one another in the clamping position of the clamping device 4 to exert a greater clamping effect on the thread located in the clamping gap 16. The lateral surfaces 17, 18 of the clamping elements 5, 6 facing the clamping gap 16 are conically configured, in portions.
The base element 7 is used to receive and guide the centrifugal force elements 9. For this purpose, the substantially cylindrical base element 7 has a wall 11 coaxial to the longitudinal axis of the upper spindle part 1, which wall is provided with a number of through-bores 12 corresponding to the number of centrifugal force elements 9. Arranged on the side of the wall 11 remote from the drive wharve 2 are half shells 13, which, as shown in Fig. 4, extend, proceeding from the through-bores 12 radially

outwardly with respect to the longitudinal axis of the upper spindle part 1. The half shells 13, in this case, adjoin the through-bores 12 in the axial direction.
In order to virtually completely surround the centrifugal force elements 9, the displaceable clamping element 6 has half shells 15 corresponding with the half shells 13 and extending in the radial direction. The half shells 13,15 being used to receive the centrifugal force elements 9 are configured corresponding to the form of the spherical centrifugal force elements 9 and adapted to their dimensions. In addition, the wall 11 has grooves 14 extending in the axial direction of the upper spindle part 1, which are arranged adjacent to the half shells 13 on the wall 11. The grooves 14 are used here to position and prevent twisting of the displaceable clamping element 6. For this purpose, the grooves 14 of the base element 7 have a width corresponding to the width of the half shells 15 so the half shells 15 are guided therein. The clamping element 6 is positioned and guided by the grooves 14 relative to the base element 7 in such a way that in the position of the clamping element 4 assembled on the upper spindle part 1, the centrifugal force elements 9 are surrounded by the half shells 13, 15 and outwardly sealed, in that the two corresponding half shells 13, 15 in the position of the clamping device 4 assembled on the upper spindle part 1 form a closed chamber. In this manner, a guidance of the centrifugal force elements 9 is achieved and the centrifugal force elements 9 are protected from soiling from thread residues, fibre material or the like.
The guidance of the centrifugal force elements 9 is achieved by a link-like guide. For this purpose, the half shells 15 of the clamping element 6 have a link inclined with respect to the horizontal and the half shells 13 of the base element 7 have a link which extends in the radial direction, in which the spherical centrifugal force elements 9 can move. The angle of the inclined link is preferably between 10° and 70°, in particular 15° to 65°.
The compression spring 8 is supported on the base element 7 and on the displaceable clamping element 6 surrounding the base element 7 and presses the latter in the

direction of the fixed clamping element 5. The transition between the clamping position and the opened position of the clamping device 4 takes place when a limit rotational speed is exceeded or fallen below during spinning operation. The limit rotational speed corresponds to the rotational speed of the upper spindle part 1, at which the force acting in the axial direction and exerted by the centrifugal force elements 9 on the displaceable clamping element 6 is less than the force acting through friction and the compression spring 8 on the clamping elements 5,6.
The exceeding of the limit rotational speed means that the centrifugal force elements 9 are pressed outwardly, with them being forcibly guided within the two half shells 13, 15 by the links. The incline of the links of the half shells 15 of the displaceable clamping element 6 leads to a force running parallel to the longitudinal axis of the upper spindle part 1 from the centrifugal force elements 9 acting on the clamping element 6, which force counteracts the force of the compression spring 8 and is greater in terms of amount. This leads to an axial displacement of the clamping element 6, so the clamping gap 16 is opened. If a doffing process of the tube is due, a ring rail, not shown, is guided downwardly to such an extent that the thread guided by the traveller circulating on the spinning ring is placed in the region of the opened clamping gap 16. In this case, it is not necessary for the thread to be wound with a full revolution around the clamping device 4. When being placed on one of the conical lateral surfaces 17,18 of the clamping elements 5, 6, the thread slides because of the conicity and the thread tension into the clamping gap 16 or the thread is placed directly into the clamping gap 16.
The falling below of the limit rotational speed owing to the following braking process leads to a reduction in the centrifugal force, so the centrifugal force elements 9 move inwardly and finally, when the spindle is at a standstill, rest on the surface of the drive wharve 2, as shown in Fig. 2, so no adequate force directed counter to the compression spring 8 is applied to the displaceable clamping element 6. The spring force presses the displaceable clamping element 6 against the fixed clamping element 5, so the clamping gap 16 is closed. The mutually complementary webs and

recesses on the end faces of the clamping elements 5, 6 engage in one another and clamp the thread located in the clamping gap 16. The subsequent doffing of the tube brings about the severing of the thread. For this purpose, the webs, which are, for example, trapezoidal or configured as a pointed tooth system, are sharp-edged in configuration, so the severing of the thread is simplified.
Once the process of the doffing is completed and the spinning operation has been resumed, on exceeding the limit rotational speed, the clamping gap 16 is opened again and this leads to a centrifuging away of the thread residue located therein, which until then remained in the clamping gap 16.

WE CLAIM:
1. Clamping device (4) for threads on a spindle of a spinning or twisting machine, the clamping device (4) being arranged on an upper spindle part (1)/ comprising a fixed clamping element (5) and an axially displaceable clamping element (6) which can be pressed against the fixed clamping element (5) by spring force, the displaceable clamping element (6) being loadable by centrifugal force elements (9) counter to the spring force by a force which spaces the displaceable clamping element (6) in the axial direction apart from the fixed clamping element (5) in such a way that a clamping gap (16) is formed between them and in that the clamping device (4) has receivers being used for the arrangement and guidance of the centrifugal force elements (9), characterised in that the receivers for the centrifugal force elements (9) are arranged on the side of the clamping device (4) opposing the clamping gap (16), a compression spring (8) being arranged between the receivers and the clamping gap (16).
2. Clamping device (4) according to claim 1, characterised in that the receivers are in each case configured as two half shells (13,15) corresponding with one another and extending in the radial direction, which surround the centrifugal force elements (9).
3. Clamping device (4) according to claim 2, characterised in that the half shells (13, 15) are arranged uniformly distributed over the periphery of the clamping device (4).
4. Clamping device (4) according to either of claims 2 or 3, characterised in that in each case a half shell (15) is arranged on the displaceable clamping element (6) and the respectively corresponding half shell (13) is arranged on a rigidly arranged base element (7).

5. Clamping device (4) according to any one of claims 2 to 4, characterised in that the half shells (13, 15) of the base element (7) or of the displaceable clamping element (6) are configured with a link inclined to the horizontal and the corresponding half shells (13,15) are configured with a link substantially parallel to the horizontal, the links being used to guide the centrifugal force elements.
6. Clamping device (4) according to claim 5, characterised in that the incline of the links in the clamping element (6) is between 10° and 70°, in particular between 15° and 65°.
7. Clamping device (4) according to any one of claims 2 to 6, characterised in that the displaceable clamping element (6) is guided with its half shells (15) in grooves (14) arranged on the outer periphery of the base element (7).
8. Clamping device (4) according to any one of claims 1 to 7, characterised in that the clamping elements (5, 6) have complementary webs and recesses on their mutually facing end faces.
9. Clamping device (4) according to any one of claims 1 to 8, characterised in that the lateral surfaces (17, 18) of the clamping elements (5, 6) are conically configured in the region of the clamping gap (16), at least in portions.
Dated this 14th day of October 2008.
HIRAL CHANDRAKANT JOSHI
AGENT FOR
OERLIKON ACCOTEX TEXPARTS GMBH

CLAMPING DEVICE

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