Nygren, Göran (Vänershöjd 3, Åmål, S-662 36, SE)
| 1. | Yarn gripper (G), comprising a first axially stationary clamping plate (D1) and a second axially reciprocal clamping plate (D2) connected to an armature (A) of a gripper opening solenoid (S), a gripper closing spring (15) loading the second clamping plate (D2) in axial direction towards the first clamping plate (D1), and a tilt mechanism (M) operatively associated to one of said first and second clamping plates (D1, D2) allowing tilting movements of the one clamping plate in relation to the axial movement direction of the second reciprocal clamping plate (D2), characterised in that the second axially reciprocal plate (D2) is arranged between the first axially stationary clamping plate (D1) and the gripper opening solenoid (S) and that the tilt mechanism (M) is operatively associated to the second axially reciprocal clamping plate (D2). |
| 2. | Yarn gripper as in claim 1, characterised in that the tilt mechanism is formed by the armature (A) itself and by a receiving bore (18) of the solenoid (S). |
| 3. | Yarn gripper as in claim 1, characterised in that the armature (A) is axially movably received in a receiving bore (18) of a solenoid coil casing (13), and that an annular gap (E) of substantially wedgeshaped crosssection is provided between the inner wall of the receiving bore (18) and the periphery of the armature (A), the axial extension of the annular gap (E) being shorter than the full axial penetration depth of the armature (A) in the receiving bore (18) in release position of the yarn gripper (G). |
| 4. | Yarn gripper as in claim 2, characterised in that an attachment part (14) is provided on an end of the solenoid coil housing (13) facing the axially reciprocal clamping plate (D2), that one first part of the receiving bore (18) is formed in the attachment part (14), and that another second part of the receiving bore (18) is formed in the solenoid coil housing (13) in continuation of the first part. |
| 5. | Yarn gripper as in claim 4, characterised in that the axial extension of the annular gap (E) substantially corresponds to the axial length of a part of the receiving bore only. |
| 6. | Yarn gripper as in claim 1, characterised in that the armature (A) has an inner end portion (19) facing a fixed core (11) which is situated within the receiving bore (18), that the outer diameter of the armature inner end portion (19) gradually decreases in the axial direction towards the fixed core (11), that the armature inner end portion (19) is continued by an essentially cylindrical armature outer section (20), the outer diameter of which corresponds to the maximum outer diameter of the armature inner end portion (19), and that the receiving bore (18) has a cylindrical inner wall. |
| 7. | Yarn gripper as in claim 1, characterised in that the armature (A) has an inner end portion (19') facing a fixed core (11) which is situated within the receiving bore (18), that the periphery of the armature (A) is cylindrical, that the receiving bore (18) has an outer end portion (27) the inner diameter of which gradually increases in axial direction away from the fixed core (11), and that the outer receiving bore end portion (27) is continued towards the fixed core (11) by a cylindrical receiving bore inner section (16), the inner diameter of which corresponds to the minimum inner diameter of the receiving bore outer end portion (27). |
| 8. | Yarn gripper as in claim 1, characterised in that the armature (A) has an inner end portion (19) facing a fixed core (11) which is situated in the receiving bore (18), that the outer diameter of the armature inner end portion (19) decreases gradually in the axial direction towards the fixed core (11), that the armature inner end portion (19) is continued by an essentially cylindrical armature outer end section (20), the outer diameter of which corresponds to the maximum outer diameter of the armature inner end portion (19), that the receiving bore (18) has an outer end portion (27) the inner diameter of which gradually increases in axial direction away from the fixed core (11), and that the outer receiving bore end portion (27) continues towards the fixed core (11) by a cylindrical receiving bore inner section (26), the inner diameter of which corresponds to the minimum inner diameter of the receiving bore outer end portion. |
| 9. | Yarn gripper as in claim 6, characterised in that the generatrice of the armature inner end portion (19) is convexly curved, preferably is a section of a circle line, and forms a smooth transition with the cylindrical armature outer end section (20). |
| 10. | Yarn gripper as in claim 7, characterised in that the generatrice of the receiving bore outer end portion (27) is convexly curved, preferably is a section of a circle line, and forms a smooth transition with the cylindrical receiving bore inner section (26). |
| 11. | Yarn gripper as in claim 1, characterised in that the gripper opening solenoid (S) is provided within a potshaped casing (9), that an open end of the casing (9) has a stop surface (16) for the axially reciprocal clamping disk (D2), and that at least one impact damper (17) is provided on the clamping plate (D2) and/or on the stop surface (16). |
| 12. | Yarn gripper as in claim 1, characterised in that an impermeable, flexible sealing structure (B) is provided between the axially reciprocal clamping plate (D2) and the gripper opening solenoid (S). |
| 13. | Yarn gripper as in claim 12, characterised in that the sealing structure (B) comprises an annular bellows (21) made of resilient material, that one end of the bellows is secured to an outer edge portion of the axially reciprocal clamping plate (D2), and that another end of the bellows is secured to the gripper opening solenoid (S), preferably to a gripper opening solenoid receiving casing (9). |
| 14. | Yarn gripper as in claim 13, characterised in that the annular bellows (21) is surrounded by a protector skirt (22), which, preferably, is secured to the axially reciprocal clamping plate (D2). |
| 15. | Yarn gripper as in claim 12, characterised in that the gripper closing spring (15) is arranged inside of the sealing structure (B) and directly between the axially reciprocal clamping plate (D2) and the gripper opening solenoid (S). |
| 16. | Yarn gripper as in claim 3, characterised in that the solenoid coil housing (13) is made of nonmetallic and nonmagnetic material, and that the periphery of the metallic armature (A) has a polished surface finish or a wear resistant coating, respectively. |
| 17. | Yarn gripper as in claim 1, characterised by a permanently freely accessible and manipulatable axial adjustment device of the axially stationary clamping plate (D1). |
| 18. | Yarn gripper as in claim 1, characterised in that the axially stationary clamping plate (D1) is secured to a holding yoke (6) fixed to the gripper opening solenoid (S), that the clamping plate (D1) has a threaded shaft (2) engaging into a threaded bore of the holding yoke (6), that a covering member (5) is secured to the threaded shaft end, that the threaded bore is formed in a preferably slotted, holding part (3) of the slotted yoke (6), and that the holding part (3) contains a locking screw (4). |
| 19. | Yarn gripper as in claim 18, characterised in that the covering member (5) forms a freely accessible handle for rotating the threaded shaft (2). |
| 20. | Yarn gripper as in claim 18, characterised in that a dust protection member (P) is provided on the threaded shaft (2) between the clamping plate (D1) and the holding part (3) of the yoke (6). |
Such yarn grippers are conventional accessory devices in yarn processing systems as in weaving machines and serve to either stop or release a yarn depending on an electric command to the yarn gripper opening solenoid. The yarn is guided along a trajectory extending between both clamping plates. The yarn gripper closing spring holds the axially reciprocal clamping plate in clamping contact with the axially stationary clamping plate to stop the yarn. As soon as the yarn gripper opening solenoid receives an electric command and becomes energised, the axially reciprocal clamping plate is withdrawn from the axially stationary clamping plate to release the yarn. A typical application of a yarn gripper is a water jet weaving machine where the respective weft yarn either has to be stopped or released without any braking effect of the yarn gripper. The clamping property of the yarn gripper is unsatisfactory if both clamping plates are permanently parallel to each other.
The yarn might contain irregularities, knots or may follow different paths through the clamping region between the clamping plates. For such reasons it is desirable that at least one of the clamping plates is able to carry out tilting movements in relation to the axial direction of the movement of the axially reciprocal clamping plate. The tiltable clamping plate automatically adapts to the yarn conditions in the clamping position of the yarn gripper in order to assure permanently good clamping properties.
In a yarn gripper Known from WO 96/27038 A the axially stationary first clamping plate is arranged between the axially reciprocal second clamping plate and the yarn gripper opening solenoid. The reciprocal clamping plate permanently is axially guided by the armature and unable to carry out any tilting movements. To the contrary, the first axially stationary clamping plate is designed to carry out the necessary adapting tilting movement in the clamping position of the yarn gripper. The tilt mechanism is operatively associated to the axially stationary clamping plate which has a lower spherical skirt seated in a concave spherical seat of the housing of the yarn gripper. The spherical skirt is secured with a predetermined clearance by a lock nut. The design of the yarn gripper is complicated.
The tilt mechanism consists of a plurality of parts. There is potential danger that contamination, or in case of an application in a water jet weaving machine, contaminated water intrudes into the tilt mechanism which is prone to failure and excessive wear. In case that the gap width between the plates has to be adjusted as needed to optimise the clamping behaviour for a respective yarn quality, the weaving machine has to be stopped, e. g. several times, to find the optimal adjustment by trial and error attempts. This is due to the fact that only the reciprocally moving plate allows gap width adjustments.
It is an object of the invention to create a structurally simple and fail-proof yarn gripper.
Said object is achieved by the features of claim 1.
Since in the yarn gripper according to the invention the axially reciprocal clamping plate is arranged between the axially stationary clamping plate and the yarn gripper opening solenoid, the axially reciprocal clamping plate directly can be connected with the armature resulting in a significant structural simplification and in reduced masses which need to be moved. Mass reduction improves the response behaviour of the yarn gripper.
Furthermore, the operative association of the tilt mechanism to the axially reciprocal clamping plate results in a further structural simplification of the design of the yarn gripper.
This tilt mechanism uses parts already necessary for the function of the yarn gripper but no additional parts. The yarn gripper is compact. The integration of the tilt mechanism into the suspension of the axially reciprocal clamping plate allows to hermetically seal the movable components against the intrusion of contamination and/or water resulting in prolonged life duration and fail-proofness of the yarn gripper.
A low number of parts is achieved by simply implementing the tilt mechanism between the aperture and an armature guiding bore of the solenoid.
The tilt mechanism is structurally extremely simple, if the relative movability of the axially reciprocal clamping plate is achieved by a combination of a cylindrical receiving bore and the armature having an inner end portion with gradually decreasing diameter. During the opening stroke the axially reciprocal clamping plate is safely guided in axial direction, while during the final part of the closing stroke and in the clamping position the axially reciprocal clamping plate is free to carry out tilting motions in order to achieve uniform clamping properties. The tilt mechanism consists of components of the yarn gripper which already are needed for the normal clamping and releasing function.
The axial guiding effect for and also the tiltability of the armature and the reciprocal clamping plate can be improved by providing an attachment part on top of the solenoid coil housing in order to prolong the receiving bore to a sufficient extent.
The annular gap of substantially wedge-shaped cross-section comes into action at the end of the closing stroke and in the clamping position of the yarn gripper, while during a major part of the opening stroke and in the release position of the yarn gripper the annular gap so to speak is overruled by the mechanical axial guiding co-action between the armature outer end section and the cylindrical receiving bore. For a proper function it might be advantageous to have an axial extension of the annular gap which substantially corresponds to the axial length of the first part of the receiving bore in the attachment part.
One of the gap forming surfaces should be inclined and curved convexly.
There are several possibilities to achieve the necessary tiltability of the reciprocal clamping plate.
According to a first approach the inner end portion of the armature is formed with the downwardly gradually decreasing outer diameter to create the annular gap of substantially wedge-shaped cross-section. The armature has an outer end section of cylindrical shape.
The receiving bore is purely cylindrical.
According to a second approach, the armature periphery is substantially cylindrical while an outer end portion of the receiving bore is formed with a gradually increasing inner diameter in a direction away from the fixed core inside the receiving bore. That widened end portion of the receiving bore provides the necessary tiltability in the end phase of the opening stroke and in the clamping position of the yarn gripper. The widened end portion may be curved convex.
According to a third approach, both above-mentioned measures are combined, i. e. the armature has an inner end with gradually decreased diameter and a substantially cylindrical outer end section, while the receiving bore has an outer end portion with gradually increased diameter and a substantially cylindrical inner end section. Both bevelled or rounded end portions c-operate in order to achieve the necessary tiltability of the reciprocal clamping plate in the end phase of the closing stroke and in the clamping position. The end portions may be curved convexly.
In order to achieve a tilting function very similar to the function of a universal joint it is expedient when the generatrice of the respective end portion is convexly curved and forms a smooth transition with the continuing cylindrical section. The generatrice even may be a section of a circle line.
For protection of the yarn gripper opening solenoid against influences from the exterior it is expedient to use a pot-shaped casing, the open end of which is provided with a stop surface for the axially reciprocal clamping disk. The stop surface defines the opened or released position of the yarn gripper. In order to keep the yarn gripper free of detrimental shock loads it is expedient to provide an impact damper between the reciprocal clamping disk and the stop surface.
It is particularly expedient to completely seal the region of the yarn gripper between the axially reciprocal clamping plate and the yarn gripper opening solenoid. Contamination and/or water are effectively hindered from intruding into the tilt mechanism and the yarn gripper opening solenoid without obstructing the free movability of the axially reciprocal clamping plate.
In order to hinder the movability of the reciprocal and tiltable clamping plate as little as possible, it is expedient to provide an annular bellows made of resilient material in the sealing structure. Both ends of the bellow are secured in tight fashion to the clamping plate and the solenoid, respectively, such that contamination and/or water are hindered from intruding.
In view of the coarse operating conditions in yarn processing systems it is expedient to provide a protector skirt for the vulnerable bellows. The protector skirt may be secured to the axially reciprocal clamping plate.
Like all other movable components of the yarn gripper also the yarn gripper closing spring ought to be encapsulated inside of the sealing structure. The spring, advantageously, directly co-acts with the axially reciprocal clamping plate.
In view to long life duration of the yarn gripper the solenoid coil housing ought to be made of non-metallic and non-magnetic material, while the periphery of the metallic armature ought to be provided with a polished surface or a wear resistant and smooth coating.
The distance or gap between both clamping plates in the release position can be adjusted with the help of a permanently accessible and actuable axial adjustment device for the axially stationary clamping plate even in operation of the yarn gripper. This improvement is of particular importance, because the yarn consuming textile machine, e. g. the weaving machine, does not need to be stopped for the trial and error optimisation of the yarn gripper function to the properties of the respective yarn.
In view to a structurally simple and compact design of the yarn gripper, the axially stationary clamping plate ought to be secured to a holding yoke which easily can be fixed to the gripper opening solenoid. The clamping plate can be secured with the help of a threaded shaft engaging into a thread bore of the yoke to allow axial adjustments of the clamping plate in relation to the axially reciprocal clamping plate, even in operation of the yarn gripper. The respectively found adjustment can be fixed by a locking screw in the slotted part of the yoke. In addition, for safety reasons a covering unit can be used to protect the threaded shaft end. The covering unit even may be provided as a handle for rotating the threaded shaft.
A dust protection member on the threaded shaft hinders the collection of lint or other contamination and assures the adjustability of the clamping plate at any time.
Embodiments of the invention will be described with the help of the drawing. In the drawing is: Fig. 1 a longitudinal section of a yarn gripper, shown in release position, Fig. 2 schematic details of the yarn gripper of Fig. 1, shown in clamping position, Fig. 3 schematic details similar to Fig. 2 of another embodiment, and Fig. 4 schematic details similar to Fig. 2 of another embodiment.
A yarn gripper G as shown in Fig. 1 in the release position comprises a first axially stationary clamping plate D1 (e. g. a round disk of plastic material) and a second axially reciprocal clamping plate D2 (e. g. a round disk of plastic material). The plate gap width may be in the order of about 1 mm only. The clamping plate D1 is fixed to a carrier 1 having a threaded shaft 2 which is threaded into a slotted holding part 3 of a C-shaped holding yoke 6. A locking screw 4 or another fastening element is provided in slotted holding part 3 in order to clamp the holding part 3 firmly around the threaded shaft 2 in order to block the threaded shaft 2 against rotation. A covering nut 5 on the free end of the threaded shaft 2 may be provided as an additional safety measure to protect the end section of the threaded shaft 2. The threaded shaft 2 may be adjusted upwardly or downwardly after loosening the locking screw 4 and/or the covering nut 5, in order to adjust the axial distance between both clamping plates D1, D2 in the shown release position of the yarn gripper G. The covering nut 5 or a similar member may even be fixed to the threaded shaft 2 to provide a handle for rotating the threaded shaft 2.
The holding yoke 6 has a foot part 7 which is secured by screws 8 to a pot-shaped housing 9 of a yarn gripper opening solenoid S.
The axially reciprocal clamping plate D2 is fixed to a disk-shaped carrier 10 which is directly connected to an armature A of substantially cylindrical shape. The armature A co-operates magnetically with a fixed core 11. Both the armature A and the fixed core 11 are surrounded by a solenoid coil 12 which is received within a non-magnetic, preferably non- metallic, coil housing 13. On top of the coil housing 13 an attachment part 14 is secured.
The attachment part 14 may be unitary with the coil housing 13. Both the attachment part 14 and the coil housing 13 constitute in Fig. 1 a cylindrical receiving bore 18 containing the fixed core 11 and also the armature A.
A yarn gripper closing spring 15, e. g. a conical helical spring, is arranged between the top side of the coil housing 13 and the lower side of the carrier 10. The upper open end of the casing 9 defines a stop surface 16 serving to limit the opening stroke of the armature A.
An impact damper 17, e. g. an annular disk of resilient material, is secured to the lower side of the carrier 10. Instead the impact damper 17 could be secured to the stop surface 16.
A sealing structure B is provided between the reciprocal clamping plate D2 and the casing 9. The sealing structure B includes an annular bellows 21 made of resilient material such as rubber or an elastomer. The upper end of the bellows 21 is clamped in an edge region of the carrier 10, while the lower end of the bellows 21 is clamped with the help of a clamping ring 23 to the outer side of the casing 9. In addition, a protector skirt 22 is provided on the carrier 10 for protecting the somewhat vulnerable bellows 21.
A tilt mechanism M is operatively associated to the axially reciprocal clamping plate D2. In the embodiment of Fig. 1, the tilt mechanism M is simply constituted by the cylindrical receiving bore 18 inner wall and the periphery of the armature A. The periphery of the armature is sub-divided into a lower armature end portion 19 the outer diameter of which gradually decreases in axial direction to the fixed core 11, e. g. with a convex curvature.
The armature lower end portion 19 is continued upwardly by a cylindrical upper end section 20 of the armature. The junction between the end portion 19 and the end section 20 is formed without any step, i. e. is smooth. Between the armature lower end portion 19 and the inner wall of the receiving bore 18 an annular gap E is thus formed which is of a substantially wedge-shaped cross-section. The axial extension of the annular gap E may correspond to the axial length of the attachment part 14. The inner diameter of the cylindrical receiving bore 18 is slightly larger than the outer diameter of the cylindrical upper end section of the armature A. In the shown release position of the yarn gripper G in Fig. 1 the armature A is axially guided with the upper cylindrical end section 20 in the receiving bore 18.
As shown in Fig. 2, in the clamping position when a yarn (not shown) is clamped between both clamping plates D1, D2, the yarn gripper closing spring 15 has moved the armature A upwardly (arrow 24) until the lower armature end portion 19 has reached or has almost reached the mouth of the receiving bore 18. The annular gap E between the inner wall of the receiving bore 18 and the armature lower end portion 19 now allows sideward tilting movements (arrow 25) of the axially reciprocal clamping plate D2. The tilting movement range is limited, however, is large enough to cope with different yarn diameters and/or yarn irregularities such that both clamping plates D1, D2 always achieve a proper clamping position in relation to each other.
In the embodiment of Fig. 3 the armature A has a continuous cylindrical periphery, i. e. the end section 20 extends from the carrier 10 down to the lower end of the armature A. The lower end of the armature may be chamfered or slightly rounded. The receiving bore 18 has a lower, cylindrical end section 26 and an end portion 27 the inner diameter of which increase gradually in an axial direction away from the fixed core 11, preferably even with a convex curvature. The armature A in Fig. 3 is shown in or almost in the clamping position of the yarn gripper where the armature and the not shown reciprocal clamping plate D2 are allowed to fulfil sideward tilting motions in relation to the axial movement direction of the armature A.
In the embodiment of Fig. 4 the measures described in connection with Figs 2 and 3 are provided in combination. That is, the armature A has an upper cylindrical end section 20 and an end portion 19 with gradually decreasing diameter. In addition, the receiving bore 18 has a lower, substantially cylindrical end section 26 and an upper end portion 27 the inner diameter of which gradually increases in a direction away from the fixed core 11. The armature A in Fig. 4 is shown in or almost in the clamping position of the yarn gripper. The annular gap E in Fig. 4 is constituted by both end portions 19,27 and the respective end sections 20,26, respectively.
The contour of the end portions 19,27 may be truly conical. However, in order to achieve a function similar to a universal joint, it is preferred to have a generatrice of each end portion 19,27 which is a convex curved line with a smooth transition into the cylindrical end section 20 or 26, respectively. The convex curvature may be a section of a circle line.
The periphery of the armature A which consists of metal, preferably is polished or has a wear resistant and smooth coating.
In each of the shown described embodiments, the armature A is magnetically attracted by the fixed core 11 as soon as the solenoid coil 12 is energised. The attracting axial force overcomes the force of the yarn gripper closing spring 15 and pulls the reciprocal clamping plate D2 downwards into abutment on the stop surface 16. Even though the axially reciprocal clamping plate D2 may be somewhat tilted in the clamping position, the armature A will be reliably pulled downwardly and such that the armature will be aligned coaxially with the axis of the receiving bore 18 in the end phase of the opening stroke, namely by the axial guiding function between cylindrical surfaces of the armature A and the receiving bore 18, respectively.
Next Patent: MAGNETIC ELEVATOR DOOR MOVER