Electromagnetic drive device for cutting device of textile machine, cutting device and yarn clearer

Abstract

To provide an electromagnetic drive device for a cutting device of a textile machine to cut off a yarn allowing particularly effective, rapid and / or exact operation and high cutting power as well of the cutting device having a cutting knife and more preferably allowing particularly long operation time without interruption and maintenance-free.SOLUTION: A piston 3 is partially guided in a core pipe 9 enclosed by a solenoid 2, the core pipe is formed by a member arranged statically relative to the piston, a gap in an axial direction extends between an end surface of the piston and an end surface formed by a corresponding surface of the core pipe and / or the piston is at least partially formed in a hollow shape and / or the piston is action-connected to a return element to return the piston moved from a rest position and the return element has a progressive, particularly non-linear spring property line.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to an electromagnetic drive device for a cutting device of a fiber machine for separating yarns, a cutting device provided with such an electromagnetic drive device, and a yarn clearer provided with such a cutting device.

[0002] Cutting devices equipped with electromagnetic drive devices for fiber machines and yarn clearers equipped with corresponding cutting devices for the working units of fiber machines are known in various configurations based on the prior art and are usually used, for example, to cut yarns when yarn defects or yarn defects are recognized.

[0003] In fiber machines with high yarn running speeds, it is necessary to separate the yarn very quickly. The typical cycle of a cutting device or an electromagnetic drive device for moving the cutting knife from the rest position to the cutting position and back to the rest position is preferably performed in less than 15 ms. In addition to the high speed required for the cutting knife and the short time of the cutting process, it is further necessary that the cutting knife has a cutting force large enough to properly separate the yarn and perform the cutting process neatly and accurately.

[0004] Fiber machines for manufacturing winding packages, such as ring spinning machines, air spinning machines, and winding machines, can wind a large number of yarns of various thicknesses and materials. The cutting device must be able to neatly separate, for example, a thin yarn material with a diameter of 0.05 mm or a thick yarn material with a diameter of 1 mm. The variety of materials that can be processed is diverse, ranging from natural fibers to artificial fibers. In particular, artificial fibers are extremely tough and may be difficult to separate.

[0005] Known cutting devices based on the prior art have a high electrical energy consumption that sometimes exceeds 400 W to 500 W, especially in the case of medium cutting power for yarns made of artificial fibers. This causes problems in processing, especially when it is necessary to cut thick portions.

[0006] The object of the present invention is to sustainably expand the possible range of diameters and materials that can be cut by a cutting device. Preferably, such a cutting device should consider the economic benefits that can be obtained by reducing not only manufacturing costs but also running costs. Furthermore, to further reduce running costs, it is preferable to achieve an extension of the maintenance interval and service interval of the cutting device. Furthermore, to reduce running costs and increase cutting output at the same time, it is preferable to improve the efficiency of energy conversion from electrical energy to cutting energy. Additionally, it is desirable to be able to provide a cutting device that reduces the configuration space so that the geometric conditions of the mounting volume can be met in an improved manner. Combining these issues, it can be said that a further object of the present invention is to preferably reduce running costs, manufacturing costs, and configuration space, while providing sustained and excellent cutting output.

[0007] The problems of the present invention are solved by the electromagnetic drive device for a cutting device of a textile machine for cutting yarn, as described in claim 1; the cutting device comprising the electromagnetic drive device, as described in claim 12; and the yarn clearer comprising the cutting device, as described in claim 13. Advantageous improvements of the present invention are described in the dependent claims.

[0008] The electromagnetic drive device according to the present invention for a cutting device of a textile machine for cutting threads has a solenoid, which has a linearly movable piston within the solenoid for driving a cutting knife support, the piston being linearly movable between a resting position and a working position different from the resting position. The solenoid further has a coil for generating a magnetic field for driving the piston. Between the end face of the piston and the corresponding face of a component of the solenoid that is fixed relative to the piston, there exists a variable axial gap in relation to the movement of the piston. In other words, in the resting position of the piston, the end face of the piston is positioned spaced apart from the corresponding face, and this axial spacing, which exists along the direction of movement, is variable by the direction of the corresponding face, i.e., the movement of the piston in the axial direction.

[0009] The solenoid, the electromagnet of the solenoid, and especially the coil of the solenoid can be powered in virtually any form, but direct power supply using a charged capacitor is preferred. The capacitor is preferably located in the area of ​​the cutting device and / or the control unit of the cutting device, which includes an electromagnetic drive mechanism.

[0010] According to a first aspect of the present invention, a piston is partially guided within a core tube surrounded by a solenoid, and the core tube is formed of a member positioned immovably relative to the piston. An axial gap extends between the end face of the piston and the end face of the core tube, which is formed by corresponding faces. At least the end face of the piston or the end face of the core tube is formed in a conical shape. More preferably, the end face of the piston and the end face of the core tube are formed to correspond to each other. Particularly preferably, the end face of the piston is formed in a conical shape, and the end face of the core tube is formed to correspond to it. Corresponding formation means a configuration of faces that correspond to each other and are congruent when superimposed. In other words, preferably, one end face forms the negative of the other end face.

[0011] A cavity is formed between the end face of the piston and the corresponding surface, particularly the end face of the core tube, at the resting position. This cavity decreases as the piston moves from the resting position to the working position, which may be the cutting position. This cavity is called the axial gap, and it extends axially with the piston and is correspondingly variable with the piston's motion in the axial direction. The size of this gap, particularly the size of the surface defining the gap axially, i.e., the end face and the corresponding surface, has been found to be important for the mode of operation and effect of the electromagnetic drive. The force acting on the piston is carried out, in particular, by the magnetic flux across this gap. Therefore, in order to increase the force acting in the existing geometry, it is necessary to increase the magnetic flux density and minimize the losses incurred, which is preferably achieved by increasing the gap in the process of constructing a conical shape. This increases the force on the piston that is generated by the magnetic field.

[0012] Particularly preferred, in order to increase the surface area of ​​the member in the void region that defines the void axially, and at the same time ensure good function of the electromagnetic drive or cutting device, a preferred configuration of the electromagnetic drive device has been specified to be an angle greater than 0°, ~50° (including 50°), preferably 10°~45° (including 45°), particularly preferably 15°~40° (including 40°), very particularly preferred 25°~35° (including 35°), and especially preferably 30°.

[0013] The angle of the piston end face is preferably related to the inclination or angle of the piston material and / or the surface of the end face with respect to the central longitudinal axis of the piston. The angle of the corresponding surface, in particular the angle of the end face of the core tube, is preferably related to the inclination or angle of the void and / or the surface of the corresponding surface or end face with respect to the central longitudinal axis of the piston or the central longitudinal axis of the core tube. Accordingly, the angle of the corresponding surface, in particular the angle in the core tube material, is preferably 180° after subtracting the piston angle in the material. More preferably, the conical portion of the piston has an angle that remains constant across the entire end face, however, configurations with angles that basically vary along the end face, and / or end faces of the piston and / or stationary members divided into multiple different sections are also conceivable.

[0014] The piston end face and the corresponding surface, preferably the piston end face and the core tube end face, are preferably formed to correspond to each other and / or angled, in particular, so that both end faces can make full contact with each other when the axial gap is closed. More preferably, the corresponding end face and / or corresponding surface of the piston are formed to be smooth or flat.

[0015] Basically, the piston and core tube may be formed from any material. Based on the reciprocating motion of the piston, the piston is preferably formed from a material having high magnetic permeability, high saturation magnetization, and low coercivity, thereby avoiding hysteresis losses and increased restoring force. In a preferred configuration of an electromagnetic drive, the piston and / or core tube are specified to be formed from a material having a magnetic saturation of preferably higher than 1.9T, particularly preferably higher than 2.0T, and / or a low coercivity of preferably less than 1300 A / m, particularly preferably less than 1200 A / m, very particularly preferably less than 800 A / m, and especially preferably less than 700 A / m. With such a configuration, it is advantageous that demagnetization losses occurring within the material can be kept as small as possible. Furthermore, the reduced coercivity can reduce the return force required for a well-closed magnetic circuit to reshape the starting position or take the resting position.

[0016] According to another preferred embodiment, the piston has a first piston segment and a second piston segment, the first piston segment being located outside the core tube, and the second piston segment being fixed to the first piston segment and protruding beyond the solenoid at its free end, extending through the core tube particularly in a direction away from the first piston segment, the free end of the second piston segment being formed to support a cutting knife support.

[0017] Preferably, the first piston segment is formed from a metal, preferably from carbon steel for high saturation magnetization, and particularly preferably from high-temperature rolled carbon steel, and / or has a carbon content of less than 1%, preferably less than 0.5%, particularly preferably in the range of 0.05% to 0.3% (including 0.3%), and most particularly preferably in the range of 0.1% to 0.2% (including 0.2%). The lower the carbon content, the greater the reduction in coercivity can be, and it has been found that the optimal coercivity is obtained with a carbon content of particularly preferred 0.1% to a maximum of 0.2%.

[0018] The core tube itself is not subjected to high forces. However, the reduction in cross-sectional area, and consequently the compression of the magnetic flux from the solenoid to the core tube, necessitates a high saturation magnetization. To minimize the demagnetization loss of the electromagnetic drive system, it is particularly preferable that the first piston segment and the core tube be formed from the same material. Another advantage is that this reduces the cost of both components.

[0019] More preferably, the axial length of the first piston segment is selected such that this axial length is equal to or greater than the simple axial length of the exposed surface of the solenoid facing the first piston segment, where the axial length of the exposed surface of the solenoid is greater than the axial length of the axial gap at the piston's resting position. This configuration, combined with the small mass of the first piston segment, provides sufficient material strength to secure the second piston segment to the first piston segment. More preferably, the axial length of the first piston segment is equal to or greater than the sum of the simple axial length of the exposed surface of the solenoid facing the first piston segment and the axial length of the axial gap at the piston's resting position. This configuration allows the magnetic field density acting in the orthogonal gap between the solenoid and the piston to be kept constant throughout the entire stroke of the piston. Preferably, for cost reasons, one end of the second piston segment is fixed to the first piston segment, particularly in its axial receiving portion, for example, by axial press-fitting. Alternative or additional fixing configurations can be selected, as long as it is ensured that the first and second piston segments are movable together in the axial direction and, more preferably, can withstand or resist the impact force resulting from the cutting process.

[0020] According to a preferred embodiment, the second piston segment is formed from a non-magnetic and / or non-magnetizable metal, particularly aluminum or special steel. This effectively prevents the risk of magnetic short circuits. A preferred configuration consisting of aluminum or special steel has a more favorable effect on the weight and stability of the piston.

[0021] The problems described above are solved, either alternatively or additionally, by forming the piston at least partially hollow. The at least partially hollow configuration of the piston allows for not only effective weight reduction but also a reduction in demagnetization losses, including eddy current propagation. The electromagnetic drive, in particular the piston, may preferably be configured according to one embodiment of the plurality of preferred embodiments described above. For example, the first piston segment and / or the second piston segment in particular may be formed hollow or as a hollow profile. More preferably, the piston or the first piston segment may be hollowed out on the back side opposite to the cutting knife support. The dimensions of the hollowed-out portion may preferably be selected such that the diameter of the hollowed-out portion of the piston or the first piston segment is configured such that the material surrounding the hollowed-out portion is outside of magnetization saturation even at the maximum cutting force generated by the electromagnetic drive.

[0022] Furthermore, the fundamental problem of the present invention is solved, alternatively or additionally, by the present invention, in which the piston is coupled to a return element for returning the piston after it has been moved from a resting position, and the return element has a progressive, particularly nonlinear, spring characteristic curve. The electromagnetic drive device may preferably be configured according to one embodiment of the preferred embodiments described above.

[0023] Preferably, the piston is engaged with a spring element that accelerates and returns the piston from the resting position in the direction toward the resting position and / or in the direction opposite to the direction of action of the coil's magnetic field. This spring element is preferably a progressive spring, and particularly preferably increases the spring force nonlinearly with increasing compression or deformation of the spring. More preferably, the spring element is a coil spring and / or is arranged to surround one section of the piston, particularly a section of a second piston segment. Even more preferably, the spring element may be at least partially located within the core tube, or at least partially penetrate into the core tube. Alternatively, preferably, a second core tube may be provided, which is more preferably located within the solenoid or the solenoid core of the solenoid, to guide the piston section that penetrates the core tube. In another preferred embodiment, the solenoid, particularly the solenoid core, core tube, or second core tube may have or form a stopper for the spring, which, when configured in this way, allows for a compressive action. The spring stopper may be provided inside the core or inside the second core tube, or it may be provided outside the core tube or outside the second core tube.

[0024] Furthermore, the fundamental problem of the present invention is solved, alternatively or additionally, by the piston being surrounded by a solenoid core positioned immobile relative to the piston, the solenoid core being manufactured by powder injection molding and / or formed from soft ferrite or from multiple layers of electrometal sheets, particularly motor metal sheets. The electromagnetic drive unit may preferably be configured according to one embodiment of the preferred embodiments described above.

[0025] The solenoid core enables improved magnetic flux within the solenoid. Preferably, the solenoid core has a sufficiently large surface area that allows the magnetic flux to reach the piston, and, according to a more preferred embodiment, additionally, the core tube. Preferably, the solenoid core is located outside the coil and has a section that protrudes axially beyond the coil, this section facing the piston section, more preferably one section of the first piston segment and one section of the core tube, while forming orthogonal gaps. This allows the magnetic field strength to be kept relatively low. In particular, low magnetic field strength can be obtained in the transition region between the solenoid core and the piston, more preferably between the solenoid core and the first piston segment, and between the solenoid core and the core tube. The piston, and especially the core tube, are also coaxially located inside the solenoid core.

[0026] The solenoid core is not subjected to high impact forces, according to a suitable configuration. Preferably, the solenoid core is provided with a large cross-section capable of guiding magnetic flux. Particularly preferably, the transition between the solenoid core and the piston, and more preferably between the solenoid core and the first piston segment and between the solenoid core and the core tube, are also configured planarly so as to eliminate magnetic saturation in the regions of these transitions. Particularly preferably, the solenoid core is formed from a soft ferrite material. Soft ferrite is useful for optimizing the mode of operation of electromagnetic drive devices. Particularly advantageous is the use of Mn-Zn ferrite, Ni-Zn ferrite, Y-Fe garnet or similar materials. Manufacturing by powder injection molding is also advantageous, enabling particularly advantageous magnetic properties and particularly high efficiency of electromagnetic drive devices. Instead of or in addition to a powder injection molding configuration, particularly following such a configuration, a sintering process can be carried out for hardening, so that the configuration is more preferably obtained in a powder injection molded article that is then sintered. Particularly by a sintered powder injection molded article configuration, manufacturing costs can be further significantly reduced.

[0027] In an alternatively advantageous configuration for the solenoid core, the solenoid core is formed from multiple layers of electrometal sheets, particularly preferably from motor metal sheets, and especially preferably from 3.2% or 6.5% Si steel sheets. This allows for particularly high permeability and magnetic saturation. Furthermore, eddy currents can be sufficiently suppressed by the layered arrangement. Preferably, all material layers have the same thickness and / or are formed from the same material as each other. More preferably, the solenoid core has at least three, particularly advantageously at least five, very particularly preferably at least ten, and especially preferably at least fifteen material layers.

[0028] According to a preferred embodiment of the present invention, the magnetically exposed surfaces in the orthogonal gap between the solenoid core and the piston, particularly the magnetically exposed surfaces between the solenoid core and the first piston segment and between the solenoid core and the core tube, are preferably larger than or equal to the magnetically exposed surfaces in the axial gap, particularly the end faces or corresponding surfaces. The magnetically exposed surfaces in the orthogonal gap between the solenoid core and the piston, particularly the magnetically exposed surfaces between the solenoid core and the first piston segment, and the magnetically exposed surfaces between the solenoid core and the core tube are preferably larger than the piston end faces or corresponding surfaces in the axial gap by at least a coefficient of 2, preferably a coefficient of 2 to 6, most preferably a coefficient of 3 to 5, and most preferably a coefficient of about 4. The magnetically exposed surfaces are, in particular, surfaces on which the magnetic field of the solenoid acts, and especially directly, on which the axial motion of the piston can be realized.

[0029] Preferably, the solenoid core is positioned directly opposite the piston, particularly the first piston segment, and more preferably the core tube, forming a second orthogonal gap. Here, "directly" means that there is no intervening physical member or element that is not assigned to or is itself a single member of either the core tube or the piston.

[0030] According to a preferred improvement form of the electromagnetic drive device, in order to keep the second orthogonal gap extending between the piston and the solenoid core surrounding the core tube as small as possible, the piston, particularly the second piston segment, is guided and arranged in the core tube with a minimum orthogonal spacing. Configured in this way, the magnetic field strength in the axial gap can be preferably increased, thereby clearly improving the efficiency of the electromagnetic drive device and thus the cutting action of the cutting device. The core tube is preferably formed as an integral member and / or as a member independent of the remaining members of the solenoid.

[0031] More preferably, the core tube has a hollow cylindrical section, and particularly preferably has a hollow cylindrical section with an inner diameter that remains equal and is adapted to the outer diameter of the piston or the outer diameter of the guided section of the piston, particularly the second piston segment, passing through the core tube.

[0032] In a more preferred configuration of the electromagnetic drive device, the solenoid has a support element, particularly just one support element, for supporting the piston, and this support element is particularly preferably formed from polyether ether ketone (PEEK). Configured in this way, a particularly good linear guide with only slight sliding friction can be obtained. Furthermore, the influence of the magnetic action of the coil on the piston can be reliably avoided.

[0033] Preferably, the material of the support element preferably has a low coefficient of friction. The support element is preferably a support sleeve and / or a linear support element. Similarly preferably, the support element surrounds a section of the piston, particularly the second piston segment, so as to be located particularly advantageously entirely and / or in close contact within the core tube. The support element is more preferably press-fitted into the core tube.

[0034] The support elements may, in alternatively suitable forms, be made of other materials such as bronze, particularly bearing bronze, silicon bronze, or phosphor bronze, brass, copper, or other metals, especially other non-ferrous metals.

[0035] According to another preferred configuration of the electromagnetic drive, the piston is configured such that the center of mass of the piston, preferably including the cutting knife support, remains within the core tube, particularly within the support element, during the maximum possible movement of the piston between the resting position and the working position, which may be an end position such as the cutting position or a position located between them. With this configuration, particularly stable and tilt-free support can be easily achieved. This allows, on the one hand, to directly improve the cutting result by a specified angle of impact of the cutting knife, and on the other hand, to keep the radial or orthogonal air gap constant and as small as possible during the entire movement of the piston between the resting position and the working position. This allows the magnetic field strength to be kept as large as possible in the axial air gap, which is important for driving the piston.

[0036] According to another aspect of the present invention, a cutting device for a textile machine for cutting yarn is provided, comprising an electromagnetic drive unit according to at least one embodiment of the preferred embodiments described above, and a cutting knife support unit having a cutting knife that is movable between a resting position and a working position such as a cutting position by the electromagnetic drive unit.

[0037] A cutting device in the sense of the present invention is a device that uses an electromagnetic drive to move a cutting knife so that it can cut a thread that is moving particularly fast, either within the cutting device or in contact with the cutting device. The cutting device and / or a thread clearer equipped with such a cutting device is preferably an autonomous or independent structural unit and / or is provided for placement in a textile machine.

[0038] The cutting force of the cutting device is directly proportional to the impact or pulse of the kinetic mass. According to a preferred embodiment, the kinetic mass is the total mass of the piston, the cutting knife support, and the cutting knife supported by the cutting knife support. When accelerating from a stationary state, the pulse supplied to the kinetic mass is independent of the kinetic mass itself, and is simply related to the time integral of the force acting on the kinetic mass. Therefore, it is preferable to increase the speed in order to increase the pulse. This can preferably be achieved by reducing the mass of the moving system. Furthermore, since the force acting on the piston is directly related to the characteristics and efficiency of the solenoid, improving the effect and mode of operation of the solenoid improves the cutting force and, consequently, the cutting result. Accordingly, a high energy effect is desired. To increase the force acting on the piston, including the cutting knife, it is preferable to increase the magnetic flux in the axial gap between the piston and the solenoid core, minimizing losses occurring in the moving and stationary systems, and similarly minimizing the return force required to return the moving system after the cutting has been performed.

[0039] The piston, coil, and solenoid core are preferably components of the solenoid. The piston is the only movable, particularly linearly movable, component of these three. Accordingly, the piston is the component that must withstand the greatest impact force in the cutting device, particularly in the solenoid, and possibly alongside the cutting knife support, and since this component is moved at high speeds during operation, strong forces act upon it. The cutting knife support or cutting knife is driven by the solenoid moving the piston between a resting position and a cutting position along a linear, particularly straight, motion trajectory, which is set by the piston or the motion of the piston. Preferably, the piston has a rotationally symmetrical shape in all its components located within the solenoid, most preferably the whole.

[0040] Preferably, a cutting knife support is positioned at the end of the piston and / or within the piston region, outside the solenoid, so that the cutting knife can be moved by the piston. The cutting knife support is a member fixed to the piston, and the mass of this member can be further reduced by an advantageous configuration, at least partially as a hollow profile.

[0041] The cutting knife support is basically formed to house the cutting knife. The cutting knife support is preferably provided to house the cutting knife in a replaceable manner. More preferably, the cutting knife support prevents the cutting knife from moving axially and / or radially during the movement of the piston and the cutting knife support, and / or prevents the cutting knife from tilting relative to the axial direction of the piston movement. The cutting knife support is preferably formed so that the cutting knife can move linearly axially or coaxially with respect to the direction of piston movement between a resting position and a cutting position.

[0042] The cutting knife may be configured in a manner that is essentially arbitrary and may have one or more cutting edges. The cutting knife is positioned indirectly or directly on a linearly movable piston, particularly preferably directly on a cutting knife support, and performs cutting by a cutting motion in the axial direction of the piston. More preferably, the cutting knife cooperates with a corresponding surface, particularly preferably a fixed or immovable corresponding surface, and very preferably, an anvil as known, to sever the thread.

[0043] In a preferred embodiment, the cutting device is configured such that the opposing end faces and corresponding faces of the electromagnetic drive unit do not come into contact with or touch each other at the cutting position, according to one embodiment of the preferred embodiments described above. With this configuration, these faces can be formed with lower hardness, and in particular, there is no need to harden them. Furthermore, the risk of the piston sticking to the corresponding face can be avoided, thereby preventing the piston from returning slowly or failing to return at all. In a preferred embodiment, contact between the faces can be prevented by setting the stroke of the cutting device to be smaller than the axial length of the axial gap.

[0044] Finally, the present invention relates to a yarn clearer for a working unit of a textile machine, comprising an electromagnetic drive and / or cutting device according to at least one embodiment of the preferred embodiments described above, and at least one sensor device for detecting the presence or absence of yarn and / or yarn defects.

[0045] A textile machine is basically any device for forming or processing at least one yarn, and preferably has a number of working units, in particular working units arranged side by side. Particularly preferably, a textile machine may be a spinning machine, or a textile machine for forming or winding a winding package, in particular a rotary spinning machine, a pneumatic spinning machine or a winding machine.

[0046] The yarn clearer may be formed in principle arbitrarily and may be provided for monitoring and / or processing the passing yarn, in particular for cutting off sections containing defects. Accordingly, the yarn clearer preferably has at least one unit for monitoring and / or processing the yarn between the yarn inlet and yarn outlet, particularly within the yarn guide passage. In particular, the yarn clearer has a cutting device according to one embodiment of a preferred embodiment for clearing and removing detected yarn defects and / or yarn flaws, i.e., for cutting off sections containing defects.

[0047] According to one of the preferred embodiments of the present invention, combined with appropriate material selection, the particularly geometric configuration described above for the component effectively avoids eddy current losses and demagnetization losses that occur when dynamically converting supplied electrical energy into kinetic energy. Furthermore, magnetic limitations such as saturation and residual magnetism (coercivity) can be improved by the selection of materials and geometric shapes used. Improved piston acceleration can be achieved by reducing the mass, thereby ultimately increasing the cutting power. Furthermore, by reducing the coercivity, the return force required to return the piston can be reduced, particularly at the end of the cutting process. Furthermore, by reducing the kinetic mass, the required return force can be further reduced. To further optimize the drive mechanism, the spring element used as the return element is preferably configured such that the spring force acting against acceleration is minimized during the acceleration phase.

[0048] The present invention is not limited to the individual embodiments described above. Individual or multiple embodiments can be combined with each other to obtain another preferred embodiment.

[0049] Next, we will describe in detail one embodiment of an electromagnetic drive device for a cutting machine of a textile machine, with reference to the drawings. [Brief explanation of the drawing]

[0050] [Figure 1] This is a schematic diagram showing the upper part of an electromagnetic drive unit for a cutting device in a textile machine. [Figure 2] Figure 1 is a cross-sectional view of the electromagnetic drive device.

[0051] The electromagnetic drive unit 1 shown in Figure 1 is provided for a cutting device in a textile machine that manufactures yarn packages, and has a cutting knife housing 4 for housing the cutting device in the yarn clearer. The cutting knife 14 incorporated in the cutting knife support 13 can cut or separate the yarn moving at high speed along the central longitudinal axis, for example, when a defect is detected. Since the cutting process must be completed within a few milliseconds based on the high yarn travel speed, particularly fast driving of the cutting knife 14 is required. Furthermore, a certain amount of cutting force and high precision are required in order to cleanly separate the yarn.

[0052] To enable this, the electromagnetic drive unit 1 has a solenoid 2. A piston 3 is linearly movable within the solenoid core 5. The piston 3 is formed from a first piston segment 3A and a second piston segment 3B, the free end of the second piston segment 3B being press-fitted and fixed into the housing of the first piston segment 3A.

[0053] The piston 3 is partially surrounded by a coil, which is not shown in the diagram. When the coil is activated, a magnetic field is formed, and the piston 3 is moved in the direction of the cutting position. To support the piston 3 precisely and simultaneously with the lowest possible friction within the solenoid core 5, the piston 3 is placed inside a core tube 9, which further contains a support element 11 made of polyether ether ketone, which the core tube 9 linearly guides the piston 3 and prevents it from tilting.

[0054] A cutting knife support 13 is detachably coupled to another free end of the piston 3, particularly the second piston segment 3B.

[0055] To obtain particularly good magnetic interaction between the stationary core tube 9 and the piston 3, the end face 7 of the piston 3 or the first piston segment 3A and the end face 8 of the core tube 9 are both formed in a conical shape. The magnetic interaction between the stationary core tube 9 and the piston 3 takes place mostly within an axial gap 6, which extends between the end face 7 of the piston 3, which is inclined with respect to the central longitudinal axis of the piston 3, and the similarly inclined end face 8 of the core tube 9, which corresponds to end face 7. The volume and length of the axial gap 6 change along the central longitudinal axis or direction of motion of the piston 3 as the piston 3 moves from a resting position to a cutting position where the thread is cut.

[0056] The end faces 7 and 8 have flat surfaces inclined at approximately 30° with respect to the central longitudinal axis of the piston 3, thereby significantly increasing the surface area compared to the configuration at a 90° angle. In this way, the magnetic interaction can be significantly optimized. To further optimize this interaction, the support element 11, piston 3, and solenoid core 5 are formed such that the orthogonal gap 10 between the piston 3 and the solenoid core 5, which surrounds the piston 3 around its entire circumference and whose volume does not substantially change with the movement of the piston 3, is as small as possible.

[0057] As described above, the second piston segment 3B is firmly held within the first piston segment 3A, and is particularly press-fitted. The second piston segment 3B is guided axially by the support element 11. Furthermore, the second piston segment 3B is formed partially hollow or at least partially as a hollow profile, such a configuration helps to further reduce the kinetic mass, thereby allowing the kinetic mass to be accelerated more effectively, thereby generating an even greater cutting force. To avoid magnetic short circuits, the second piston segment 3B is manufactured from a non-magnetic and / or non-magnetizable material, particularly aluminum or a non-magnetic special steel. At the same time, the first piston segment 3A is hollowed out on the side of the piston 3 opposite to the second piston segment 3B, thereby reducing the eddy currents and demagnetization losses that occur therein.

[0058] To ensure a reliable and rapid return of the piston 3 from the cutting position to the resting position, a progressive coil spring 12 is positioned to surround the second piston segment 3B, increasing its stress as the piston 3 moves to the cutting position. When the coil becomes inactive, the coil spring 12 pushes the piston 3 back to the resting position, and the motion cycle, consisting of the electromagnetic movement of the piston 3 from the resting position to the cutting position and the spring-driven return movement of the piston 3 to the resting position, preferably takes place within 10 ms to a maximum of 15 ms. The coil spring 12 is positioned between the end face 7 of the piston 3 and a spring stopper provided on the core tube 9, and the piston 3 contacts this spring stopper at least each time during its movement from the resting position to the cutting position. In another preferred configuration, the coil spring 12 is gripped between the end face 7 of the piston 3 and the end face of the support element 11.

[0059] To further optimize the magnetic interaction, the first piston segment 3A and core tube 9 are formed from a material having a high magnetic saturation of over 1.9T and a low coercivity of less than 800 A / m. For the first piston segment 3A and core tube 9, this configuration of the electromagnetic drive unit 1 uses high-temperature rolled carbon steel with a low carbon content of 0.1% to 0.2%.

[0060] The solenoid core 5 is further formed from multiple layers of electrometallic sheets bonded together, particularly from motor metal sheets. In a further preferred configuration, the solenoid core 5 is made of soft ferrite, particularly Mn-Zn ferrite, Ni-Zn ferrite, Y-Fe garnet, or similar, in which case manufacturing by powder injection molding is particularly advantageous. These means are particularly useful in reducing eddy currents and their undesirable effects on the rapid acceleration of the piston 3 to the extent that they no longer have a significant impact. [Explanation of Symbols]

[0061] 1. Electromagnetic drive device 2 Solenoids 3 pistons 3A First piston segment 3B Second piston segment 4. Cutting knife storage section 5. Solenoid core 6. Axial gaps 7 End face of the piston 8. Corresponding surface or end face of the core pipe 9 core tubes 10 Orthogonal gaps 11 Support elements 12. Return element / coil spring 13 Cutting knife support 14 Cutting Knives

Claims

1. An electromagnetic drive (1) for a cutting device of a textile machine for cutting off a yarn by means of a solenoid (2), comprising: a piston (3) guided linearly in said solenoid (2) for driving a cutting knife support (13), said piston (3) being linearly movable between a rest position and a working position; a coil for generating a magnetic field that drives said piston (3); an axial gap (6) variable in relation to the piston movement between an end face (7) of the piston (3) and a corresponding face of a member of the solenoid (2) that is arranged stationary relative to the piston (3); In a drive device (1), the piston (3) is partially guided, in particular by a support element (11), in a core tube (9) surrounded by the solenoid (2), the core tube (9) being formed by the element arranged stationary relative to the piston (3), the axial gap (6) extending between the end face (7) of the piston (3), in particular of conical shape, and an end face (8) of the core tube (9), formed by the corresponding surface and in particular corresponding to the conical end face (7) of the piston (3); and / or - the piston (3) is at least partially hollow, and / or the piston (3) is operatively connected to a return element (12) for returning the piston (3) displaced from the rest position, the return element (12) having a progressive, in particular non-linear, spring characteristic curve; and / or The piston (3) is surrounded by a solenoid core (5) that is arranged stationary relative to the piston (3), the solenoid core (5) being manufactured by powder injection molding and / or made from soft ferrite or made from multiple layers of electrical sheet metal, in particular motor sheet metal. An electromagnetic drive device (1) characterized in that:

2. 2. The electromagnetic drive device (1) according to claim 1, characterized in that the piston (3) comprises a first piston segment (3A) and a second piston segment (3B), the first piston segment (3A) being arranged outside the core tube (9), the second piston segment (3B) being fixed to the first piston segment (3A) and projecting with its free end beyond the solenoid (2), in particular extending through the core tube (9) in a direction away from the first piston segment (3A), the free end of the second piston segment (3B) being formed to support the cutting knife support (13).

3. 3. The electromagnetic drive device (1) according to claim 2, characterized in that the first piston segment (3A) has an axial length equal to or greater than the simple axial length of an exposed surface of the solenoid (2) located opposite the first piston segment (3A), and the axial length of the exposed surface of the solenoid (2) is greater than the axial length of the axial gap (6) of the piston (3) in the rest position.

4. 4. The electromagnetic drive device (1) according to claim 2 or 3, characterized in that the first piston segment (3A) and / or the core tube (9) are made of hot-rolled carbon steel and / or have a carbon content of less than 1%, in particular less than 0.5%, or in the range of 0.1% to 0.2%.

5. 4. The electromagnetic drive device (1) according to claim 2 or 3, characterized in that the second piston segment (3B) is made from a non-magnetic and / or non-magnetizable metal, in particular from aluminum or stainless steel.

6. 4. The electromagnetic drive device (1) according to claim 1, wherein the angle of the conical end face (7) of the piston (3) and / or the angle of the corresponding end face (8) of the core tube (9) relative to the axial movement axis of the piston (3) is between 15° and 40°.

7. 4. The electromagnetic drive device (1) according to claim 1, wherein the piston (3) is guided and arranged with a minimum perpendicular spacing within the core tube (9) in order to keep the second perpendicular gap (10) extending between the piston (3) and a solenoid core (5) surrounding the core tube (9) as small as possible.

8. 4. The electromagnetic drive (1) according to claim 1, further comprising a single support element (11) arranged in the core tube (9) for supporting the piston (3), the support element (11) being made in particular of polyetheretherketone.

9. 4. The electromagnetic drive device (1) according to claim 1, wherein the center of mass of the piston (3) remains within the core tube (9), in particular within the support element (11) arranged within the core tube (9), during the movement of the piston (3) between the rest position and the disconnection position.

10. 4. The electromagnetic drive device (1) according to claim 1, wherein the magnetically exposed surface of the orthogonal air gap (10) between the solenoid core (5) of the solenoid (2) and the piston (3) is equal to or greater than the magnetically exposed surface of the axial air gap (6), the magnetically exposed surface of the orthogonal air gap (10) preferably being greater than the magnetically exposed surface of the axial air gap (6) by a factor of 3 to 5.

11. 4. The electromagnetic drive device (1) according to claim 1, wherein the piston (3) and / or the core tube (9) are made of a material having a magnetic saturation greater than 1.9 T and / or a coercive force less than 1300 A / m.

12. 1. A cutting device for a textile machine for separating yarns, comprising: an electromagnetic drive (1) according to any one of claims 1 to 3, a cutting knife support (13) with a cutting knife (14) movable by said electromagnetic drive (1) between a rest position and a cutting position; A cutting device comprising:

13. 1. A yarn clearer for a working unit of a textile machine, comprising: an electromagnetic drive (1) according to any one of claims 1 to 3, at least one sensor device for detecting at least the presence or absence of a yarn and / or for detecting a yarn defect; Equipped with thread clear.

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