Filtering apparatus

Abstract

This invention relates to a filtering device for filtering a plastic melt, comprising: a housing having an inlet channel and an outlet channel; and a filter pin disposed between the inlet channel and the outlet channel and housed in a pin socket of the housing in an axially displaceable and rotatable manner, wherein the filter pin has a filter portion having a filter element and a discharge channel, wherein in an operating position of the filter pin, the filter portion is disposed between the inlet channel and the outlet channel and connects the inlet channel to the outlet channel, and in an initial position of the filter pin, the discharge channel is flowably connected to the inlet channel and extends through the filter element to a discharge outlet of the filter pin, wherein the filter pin presents different rotational positions in the pin socket on the one hand in the operating position and on the other hand in the initial position, wherein an inlet port of the discharge channel located on the outer circumference of the filter pin is located in a circumferential segment of the filter pin, the inlet port being rotatably offset relative to the inlet channel of the housing in the operating position of the filter pin, and being configured in the initial position of the filter pin to overlap with the inlet channel.

Description

[Technical Field]

[0001] The present invention relates to a filtering device for filtering plastic melt, comprising: a housing having an inlet channel and an outlet channel for the melt; and a filter pin disposed between the inlet channel and the outlet channel and axially displaceable and rotatable in a pin socket of the housing, wherein the filter pin has a filter portion with a filter element and a discharge channel, wherein in the operating position of the filter pin, the filter portion is disposed between the inlet channel and the outlet channel and connects the inlet channel and the outlet channel to each other, and in the initial position of the filter pin, the discharge channel is flowably connected to the inlet channel and passes through the filter element to the discharge outlet of the filter pin. [Previous Technology]

[0002] This filtration device for filtering molten plastic is generally referred to in the art as a filter replacement device because filter pins, movably guided in the housing, can be pushed out of the housing to a filter replacement position, in which the filter device can freely access or protrude from the housing to the extent that the filter element can be replaced, see the extent to which it protrudes from the housing to the replaceable filter element, see, for example, DE 10 2010 025 163 A1, or DE 20 2010 017 247 U1, or DE 10 2012 006 563 B3, DE 10 2006 050 683 A1 and DE 195 09 059 C1. In order to enable continuous movement of the system in this condition, two or more filter pins, each having a filter element, are movably housed in the housing and, in their operating positions, each create a path for the fluid to be filtered from the inlet passage to the outlet passage of the housing. If one of the filter pins moves to the filter replacement position, the fluid must still pass through at least one other filter pin or its filter element held in the operating position to be transferred from the inlet side to the outlet side. For easier removal or replacement of the filter, the pin may also be rotated to the filter replacement position, for example, via a sliding guide, when removed from the housing, see DE 10 2014 016 634 A1.

[0003] In this condition, the filter pins are guided into their respective pin sockets in the housing with almost no clearance, or the fluid is sealed to the extent that when the filter portion of the pin is assembled between the inlet and outlet channels in the operating position, the molten plastic can only pass through the pin socket, and the molten plastic cannot be pushed through the space between the adjacent pin portion and the pin socket wall.

[0004] Filtering devices are commonly used to remove unwanted foreign particles from molten plastics (e.g., in the form of polymer melt) by means of filtration, as such foreign particles can lead to incorrect production or quality loss. These filtering devices have become increasingly important in the recycling of thermoplastic materials.

[0005] The lifespan of filters used for this purpose varies depending on the degree of contamination of the individual fluids or plastics to be filtered, so that as the degree of contamination increases, the filters must be cleaned or replaced.

[0006] Additionally, filter changers can also be used to remove stationary defective melt during the start-up phase of a production cycle or before the plastic batch is fed into downstream processing systems (such as pelletizers). When the process starts, the melt typically has not yet reached the required temperature, or, for example, during color changes, contamination or residues from different coloring materials may remain in the system's channels, making the initially flowing material unusable and potentially clogging the filter of the filter changer. Depending on the size of the system, sometimes a substantial amount of material, up to half a metric ton or even a metric ton, is removed as waste, and melt suitable for further processing can then be fed through the filter element to the downstream further processing system.

[0007] During the start-up process, material discharge can be achieved by a specific start valve, which may be used, in particular, upstream or possibly downstream of the filter replacement device, to remove unsuitable material, for example, by allowing the unsuitable material to flow or drip onto the floor or collect it in a collection container.

[0008] To avoid such a separate start-up valve, it has also been suggested that the filter replacement device itself be used to discharge material during the start-up process. For this purpose, for example, the filter pin can be pulled in or out of the housing to the extent that the filter pin blocks the pin socket on one side of the inlet channel, but on the other hand, the inlet channel opens to the pin socket without being blocked by the filter pin, and thus the molten material can flow into the pin socket, collect there, and flow out of the housing on the unblocked side of the pin socket. If the filter pin moves back to its operating position, the filter pin will clear the start-up material still in the pin socket from the pin socket. However, the plastic molten material flowing freely into the housing or collected in the pin socket causes contamination of the filter replacement device and often also leads to increased wear, because, for example, coked plastic components can adhere to the housing and then have to be torn off when the filter pin is pushed back. Additionally, the axial drive requires a long adjustment range and therefore a long overall length, so that on the one hand, the filter pin can be moved out of the housing to a filter replacement position on one side, and on the other hand, the filter pin can be moved back in the opposite direction beyond the operating position for initial discharge during startup.

[0009] In order to discharge materials during the start-up phase, it has also been proposed to provide a specific discharge channel in the filter pin and move the filter pin to the start-up position, in which the discharge channel with a peripheral inlet opening is aligned with the housing-side inlet channel and the filter pin protrudes slightly from the housing, so that the discharge outlet of the discharge channel provided here is located outside the housing and the material or fluid no longer contaminates the housing, but can drip directly from the filter pin onto the floor.

[0010] Patent document DE 10 2014 009 768 B4 illustrates such a filter replacement device having a filter pin that enables this drainage function. A discharge channel extends through a central mesh that axially passes through the filter chamber of the filter pin, such that the discharge channel is guided through the filter element, as if through a tube, to guide molten plastic received from the inlet channel of the housing through the filter element of the pin to the end face of the pin protruding from the housing, from which the molten plastic can then drip onto the floor.

[0011] Because the filter element typically requires a sufficient flow cross-section and is sometimes longer on the inlet side than the inlet channel in the housing to allow the filter material to be distributed on the filter, the inlet port of the discharge channel is configured to be axially offset from the inlet channel relative to the housing. This means the filter pin must be adjusted quite far overall to align the inlet port of the discharge channel with the inlet channel on the housing side. Therefore, the device is quite large in the axial direction. On the other hand, achieving a tight fit between the filter pin and the pin socket is quite difficult, especially in the area around the inlet channel. This is because the back pressure in front of the filter element increases here, requiring a certain amount of space on the circumferential wall of the filter pin around the filter element to ensure a tight fit between the filter pin and the pin socket.

[0012] In view of the above background, a potential object of the present invention is to provide an improved filtration device of this type that avoids the disadvantages of the prior art and improves upon the prior art in an advantageous manner. Specifically, the compact design of the filtration device should allow, for example, easy and reliable discharge of materials unsuitable for further processing through the filter elements during the start-up process, without causing contamination and wear of the filter replacement device or even requiring a separate start-up valve. [Summary of the Invention]

[0013] According to the present invention, this task is accomplished by a filtering device as described in technical solution 1. A preferred embodiment of the present invention is the subject matter of the accompanying technical solution.

[0014] Therefore, it is recommended that the filter pin be rotated relative to its operating position to move it to the starting position. According to the invention, the filter pin presents different rotational positions in the pin socket, one in the operating position and the other in the starting position, wherein the inlet port of the discharge channel located on the outer circumference of the filter pin is located in a circumferential section of the filter pin, the inlet port being rotatably offset relative to the inlet channel of the housing in the operating position of the filter pin, and overlapping with the inlet channel in the starting position of the filter pin. Due to the rotational positioning movement of the filter pin to the starting position and the rotational offset between the inlet of the filter device on one hand and the inlet of the discharge channel on the other, the filter pin can be quite short in the axial direction, thus achieving a short positioning movement to the starting position and ultimately achieving a compact overall design of the filtration device. Simultaneously, sealing problems between the filter pin and the pin socket in the housing in the operating position can be avoided.

[0015] In an advantageous further development of the invention, the rotational adjustment movement of the filter pin can be superimposed with the axial adjustment movement of the filter pin to adjust the filter pin between its operating position and its starting position. This type of combined rotation and offset makes it possible to achieve reliable discharge of the melt or fluid to be discharged, regardless of short positioning movements and compact design. Specifically, the superimposed axial movement used to move the filter pin from the operating position to the starting position can be used to move the filter pin, which is completely or substantially flush with the housing in the operating position, slightly outside the housing to ensure that the plastic melt flowing out of the discharge channel does not get trapped in or on the housing, but drips directly from the filter pin.

[0016] Viewed axially, the starting position of the filter pin can be located between the operating position and the filter replacement position, wherein the filter element of the filter pin can be freely or sufficiently accessed for filter replacement, particularly extending substantially completely out of the housing. However, in this starting position, the filter element can still be fully or at least partially positioned inside the filter housing, but on the other hand, the filter element can be moved away from the inlet channel of the housing to allow fluid flowing in via the inlet channel to enter the discharge channel.

[0017] In order to enable a quick switch from the starting position to the operating position, in a further development of the invention, the axial adjustment range of the filter pin from the operating position to the starting position can be shorter than the axial adjustment range from the starting position to the filter replacement position. Specifically, the starting position of the filter pin can be close to its operating position, such that in the starting position, the filter element of the filter pin is already or still fully disposed inside the housing.

[0018] Because the start-up or discharge position is configured between the operating position and the filter replacement position, the maximum adjustment range in the axial direction is limited to the distance between the operating position and the filter replacement position. Specifically, it is not necessary to move the filter pin from the operating position to the opposite side in order to move it to the start position once and then to the start position again, as is the case with conventional filter replacement devices that discharge material into the housing in the start position.

[0019] In a further development of the invention, it is advantageous that the filter pin does not need to be rotated and adjusted when it moves directly from the operating position to the filter replacement position, or conversely, directly from the filter replacement position to the operating position. Even if the starting position exceeds the limit when viewed axially, the filter pin can move directly between the operating position and the filter replacement position without rotation or twisting. If the filter pin will move directly to the filter replacement position, or conversely, directly to the operating position after filter replacement, it is not necessary to align the discharge channel with the inlet channel on the housing side, and the rotational actuation movement component performed when moving to the starting position can be eliminated.

[0020] In an advantageous further development of the invention, the rotary drive for rotating the filter pin in the pin socket can be decoupled from or coupled to the filter pin so that the filter pin can be rotated to move to the starting position, and the rotary drive can be released or adjusted when the filter pin is moved directly between the starting position and the filter replacement position.

[0021] The releasable coupling between the rotary actuator and the filter pin may advantageously include a coupling member or coupling half that can engage and disengage in the axial direction (i.e., substantially parallel to the longitudinal axis of the filter pin). Specifically, the coupling can be configured to engage and disengage by axially moving the filter piston. If the rotary actuator is to be coupled to rotate the filter pin to move to a starting position, the rotary actuator may, for example, move to a determined coupling position, and then the filter pin may be axially moved into the coupling position to be coupled to the rotary actuator and then rotated by the rotary actuator. Conversely, the filter pin may be decoupled from the rotary actuator by axial displacement, such that the rotary actuator may then be moved back to a passive waiting position in which the filter pin may move past the axial starting position without colliding with the rotary actuator.

[0022] For example, the rotary actuator may include an adjusting actuator having an operating direction that travels transversely to the longitudinal axis of the filter pin and can be substantially parallel to the tangent of the filter pin. For example, a pressure medium actuator may be used, which can be configured as a pneumatic or hydraulic cylinder. When coupled, the adjusting actuator can act on the filter pin in a crank-driven manner to rotate the filter pin in the pin socket.

[0023] In an advantageous further development of the invention, the rotary actuator can be configured to rotate the filter pin in its socket when the filter pin is axially stationary and / or to rotate the filter pin independently of axial adjustment. Therefore, unlike linked rotary control, it is not necessary to simultaneously adjust the filter pin axially to achieve rotation. Specifically, this makes it possible to move the filter pin axially only without a rotating component, for example, when the filter pin is to be moved directly from the operating position to the filter replacement position. Since the rotary adjustment is only performed when actually needed, the filtration device achieves overall low-wear operation.

[0024] In an advantageous further development of the invention, the axial drive for adjusting the filter pin in the longitudinal direction of the filter pin or in the longitudinal direction of the pin socket may comprise an adjusting actuator in the form of a pressure cylinder (e.g., a pneumatic or hydraulic cylinder), which may be substantially coaxial with the filter pin and disposed on the end face of the housing. However, in principle, other axial drives are also possible, such as those in the form of a shaft motor or an adjusting actuator with an intermediate lever gear.

[0025] To achieve a compact design, in an advantageous further development of the invention, the axial drive and the rotary drive can be configured on the same side of the housing, particularly on the side of the housing opposite to the filter replacement and / or drainage side of the housing. The filter replacement and / or drainage side of the housing refers to one side of the housing on which the filter piston extends slightly beyond the housing to discharge the fluid to be drained during startup or to allow the filter device to be replaced in the filter replacement position. By configuring the axial drive and the rotary drive on opposite sides of the housing, filter replacement is not impaired and there is no risk of the drives being contaminated by the fluid to be drained, which drips from the filter pin when the discharge channel is in the initial position of the filter pin. Meanwhile, the filter device can be generally compact because the axial drive and the rotary drive can be configured overlappingly on the housing side. If the housing is perpendicular to the longitudinal axis of the filter pin when viewed axially, the axial drive and the rotary drive can be configured to at least partially overlap each other.

[0026] However, the rotary drive (especially when designed in the form of a pressure cylinder) may protrude toward or be disposed thereon an adjacent housing side, wherein the adjacent housing side is adjacent to the housing side on which the axial drive is provided.

[0027] The rotation of the filter pin between the operating position on one side and the discharge start position on the other side can be relatively small, for example, between 20° and 120° or between 30° and 90°, that is, the filter pin can rotate by an angle between 30° and 60° in order to move from the operating position to the start position or to turn the inlet port of the discharge channel back to the section of the inlet channel leading to the pin socket.

[0028] The discharge channel preferably has its discharge outlet or discharge port in the end portion of the filter pin, which moves out of the housing when approaching the start position. Specifically, the discharge channel may be open on the end face of the filter pin, allowing the discharged fluid to flow out from or drip from the end face of the filter pin. This ensures that the fluid to be drained does not drip into or contaminate the housing, but drips directly from the filter pin, even within a small axial adjustment range between the operating position and the start position.

[0029] In a further development of the invention, at least in the initial position of the filter pin, the discharge channel can be configured in a continuously inclined manner from its inlet to the discharge outlet, such that gravity helps to allow the fluid to be discharged to flow out of the filter pin. For example, the discharge channel may have an inlet portion extending from the outer circumference of the filter pin to its center, and then an axial portion extending to the end face of the filter pin and having an inclined profile.

[0030] In a further development of the invention, the discharge channel may also have a cross-section that increases toward the discharge outlet, so that the plastic melt to be discharged has a more convenient time to flow out of the discharge opening and experiences reduced flow resistance along the discharge channel.

[0031] In an advantageous further development of the invention, the discharge passage may be widened in a conical shape toward the outlet opening. This conical profile of the discharge passage ensures, on the one hand, an increased cross-section and on the other hand, access to the sloping floor.

[0032] The discharge channel may extend through an axial column that bridges the filter portion of the filter pin in an exposed manner and may preferably contain the longitudinal central axis of the filter pin. The axial column may be configured as a mesh extending through the filter chamber of the filter pin or through its filter portion. Specifically, the filter element may have a curved filter screen that extends around the column. When the filter pin is in its operating position, the filtered fluid or the fluid to be filtered flows laterally around the column as fluid flows from the inlet side to the outlet side. The discharge channel passes through the column.

[0033] In an advantageous further development of the invention, several adjustable filter pins can be disposed within the housing to enable continuous operation. Specifically, a second filter pin can be axially displaced and housed in a second pin socket, wherein the inlet and outlet channels of the housing can each be configured to be bifurcated to provide access to both the first and second filter pins. This bifurcated design of the inlet and outlet channels allows the fluid to be filtered to selectively flow from the inlet side to the outlet side individually via each filter pin or from the inlet side to the outlet side together via both filter pins. In the event of filter replacement, the material to be filtered can continue to be filtered through at least one other filter pin held in the operating position and flow from the inlet side to the outlet side. If two or all filter pins are in the operating position, maximum output can be achieved, or the fluid can then flow through all filter elements of all filter pins via the bifurcations.

[0034] The second filter pin may have a starting position in which the inlet channel is disconnected from the outlet channel and the inlet channel is only flow-connected to the periphery of the housing via the discharge channel in the first filter pin.

[0035] Advantageously, a control device is provided, which in particular coordinates or controls the adjustment of the two filter pins or their driving mechanism when they are moved to the starting position by means of axial displacement and rotational adjustment of the first filter pin to its starting position and the second filter pin to its starting position by means of axial adjustment only, wherein the second filter pin blocks the flow path assigned to it from the inlet side to the outlet side.

Implementation Method

[0037] As shown in the figure, the filter device 1 can be configured as a filter changing device, which may have two adjustable filter pins 7 and 18 for continuous operation. If one of the filter pins is in its filter changing position for filter replacement, see Figure 2, the material to be filtered can be filtered through the other filter pin, which is still ready for operation. If both filter pins 7 and 18 are in their operating positions, see Figure 1, the material to be filtered can be passed through both filter pins 7 and 18.

[0038] The filter device 1 includes a housing 2, wherein two pin sockets 5, 6 are configured to slidably receive two filter pins 7, 18, wherein at least one of the filter pins 7 is also rotatable in the associated pin socket 6. The two pin sockets 5, 6 may be configured, in particular, for example, in the form of cylindrical slots, such as holes, wherein a diameter jump may also be provided, for example, by rotation or similar machining.

[0039] The filter pins 7 and 18 are also substantially or at least segmentally cylindrical, especially circular cylindrical, profiled to fit precisely or without clearance and to seal against the viscous molten plastic in the pin socket 6.

[0040] Specifically, the filter pins 7 and 18 may each have two cylindrical profile end portions, and between the end portions, the filter pins 7 and 18 each have a filter portion 8, each filter portion having a filter device 9 in the form of, for example, an arc-shaped bend, wherein a plate filter or other filter package may also be used as needed.

[0041] In this filter section 8, filter pins 7 and 18 are each gradually narrowed in diameter and / or have transverse grooves and / or are flattened and / or gradually narrowed to allow the fluid to be filtered, especially polymeric plastic melt, to flow laterally through the pin socket 6. Alternatively or additionally, it is also possible to widen or specially contour the pin socket 6 in the area where the filter element 9 of the filter pin 7 is positioned in its operating position to allow flow laterally to the other side of the socket after passing through the filter element.

[0042] As shown in the figure, the housing 2 includes an inlet channel 3 and an outlet channel 4, which are located on or accessible to opposite sides of the housing and are respectively connected to or laterally connected to two pin sockets 5 and 6. The inlet channel 3 and the outlet channel 4 may each branch from a common opening to the two pin sockets 5 and 6, see, for example, Figures 1 and 2.

[0043] The two filter pins 7 can be axially adjusted by axial actuators 17 in the pin sockets 6, wherein the axial actuators 17 may, for example, have two pressure cylinders 19, 20, each of which may be disposed in the pin socket 6 or on the end face in front of the filter pin 7 housed in the pin socket. The pressure cylinders 19, 20 may be disposed, particularly parallel to or coaxial with the longitudinal axis of the filter pin, and supported or mounted on the housing 2, wherein, for example, the telescopic and extendable piston rods of each pressure cylinder 19 and 20 may be connected to one of the filter pins 7 so that the filter pin 7 or 18 can be axially moved in the pin sockets 5, 6 by retracting and extending the piston rods.

[0044] As shown in Figure 2, the axial drive 17 can move the filter pins 7 and 18 to opposite sides outside the housing 2 to the filter replacement position, in which the filter element 9 on the filter portion 8 of the filter pin 7 can be freely accessed, allowing the filter element to be replaced or cleaned. For example, if one of the filter pins 7 is in the filter replacement position, the cylindrical end portion of the filter pin 7 retained in the pin socket 6 can block the inlet passage 3, or more precisely, its branch leading to the pin socket 6, so that fluid can only flow to the second pin socket 5 of the other filter pin 8 and be filtered there.

[0045] As shown in Figures 3 to 7, one of the filter pins 7, preferably the underground filter pin 7, also has a discharge channel 10 to separate unused material when the system is started, as described at the beginning.

[0046] The discharge channel 10 can extend substantially axially through the filter pin 7, through the filter element 9, and has a transverse channel portion 21 that extends laterally through the pin on the upstream or inlet side. The discharge channel has an inlet port 12 that opens on the outer circumference of the filter pin 7 (especially its cylindrical end portion) and is connected on the other hand to an axial channel portion 22 that passes centrally through the filter pin 7 in the axial direction and opens the end face of the filter pin 7, or has a discharge outlet 11 therein, see FIG7.

[0047] Specifically, the discharge channel 10 extends through the post 23 of the filter pin 7 via its axial channel portion 22. The post is configured in the filter portion 8 of the filter pin 7 and forms the previously described gradually narrowing diameter region to allow the material to be filtered to flow laterally through the pin socket 6. The post 23 may include the longitudinal central axis of the filter pin 7 and may connect the two described cylindrical end portions of the filter pin 7.

[0048] As illustrated in Figures 6 and 7, at least when the filter pin 7 is in its initial position, the discharge channel 10 can be configured in a continuously inclined manner from the inlet port 12 toward the discharge outlet 11. Alternatively or additionally, the discharge channel 10 may have a cross-section that continuously or gradually increases in the flow direction or toward the discharge outlet 11, at least in the region of its axial channel portion 22. Specifically, the discharge channel 10 may be configured as conical and expand toward the discharge opening 11, at least in its axial channel portion 22.

[0049] The discharge passage 11 extends beyond the filter element 9 or bypasses the filter element 9. Viewed axially, the inlet port 12 and the discharge outlet 11 are located on opposite sides of the filter element 9 to guide the fluid to be discharged through the filter element 9.

[0050] The transverse channel portion 21 is configured in the filter pin 7 such that the inlet port 12 is open on its outer circumference within the section of the filter pin 7. More precisely, when viewed from the operating position according to FIG. 1 and / or when viewed from the filter replacement position according to FIG. 2, the inlet port itself is not located in the same section as the inlet channel 3; more precisely, the inlet port leads to the pin socket 6. In other words, when the filter pin 7 moves back and forth between the operating position and the filter replacement position shown in FIG. 1 and FIG. 2 by means of the axial drive 17, the inlet port 12 of the discharge channel 10 does not pass through the inlet channel 3 and is not in flow communication with the inlet channel 3.

[0051] In order to make the discharge channel 10 with the inlet port 12 flow in connection with the inlet channel 3 in the discharge position between the filter pin 7 and the filter replacement position of the filter pin, the filter pin 7 is rotated in the pin socket 6 by the rotary drive 14.

[0052] For this purpose, the filter device 1 includes a rotary actuator 14, which may have a pressure cylinder or adjusting actuator 16 arranged transversely to the longitudinal axis of the filter pin. The adjusting axis or direction of action of the adjusting actuator may be aligned transversely to the longitudinal axis of the filter pin, and in particular parallel to the tangent of the filter pin 7. For example, the adjusting actuator 16 of the rotary actuator 14 may be disposed on the side of the axial actuator 17 of the housing 2 and supported on the housing 2 and / or on the bearings for the axial actuator 17, in particular in such a way that the working head of the adjusting actuator 16 may move transversely to the longitudinal axis of the filter pin through the piston rod connected thereto to the axial actuator 17.

[0053] The rotary drive 14 can be releasably connected to the filter pin 7 via the coupling 24 so that the rotary drive 14 can be coupled when the filter pin 7 is rotated to its starting position. On the other hand, the rotary drive 14 can be decoupled via the coupling 24 so that the filter pin 7 can be moved directly between the operating position and the filter replacement position without affecting the rotary drive 14 and without rotating components, as illustrated in Figures 1 and 2.

[0054] The coupling member 24 may, for example, be engaged with the piston rod of the axial drive 17, which is non-rotatably connected to the filter pin 7, wherein the coupling member 24 may have a coupling plate 25 acting as a crank, which is non-rotatably connected to the filter pin 7, and particularly non-rotatably connected to the piston rod of the filter pin and protruding laterally therefrom, see Figures 3 and 4.

[0055] To couple the rotary drive 14 to the filter pin 7, the rotary drive 14 may first extend to a coupling position in which, as the filter pin 7 moves axially, the working head 26 of the rotary drive 14 reaches a position swept by the coupling piece 25 of the coupling member 24. When the rotary drive 14 moves to its coupling position, the filter pin 7 may still be in the operating position, see Figure 3.

[0056] In order to couple the rotary drive 14, the axial drive 17 moves the filter pin 7 slightly in the axial direction until the coupling piece 25 engages with the working head 26, see Figure 4.

[0057] Advantageously, the coupling position of the filter pin 7 can be selected such that when viewed axially, the inlet port 12 of the discharge channel 10 is positioned to fit the inlet channel 3, but is still rotatably offset from this inlet channel 3, see Figure 4.

[0058] In order to make the discharge channel 10 flow-connected with the inlet channel 3, the rotary drive 14 is then actuated to rotate the filter pin 7 until the inlet port 12 of the discharge channel 10 overlaps with the inlet channel 3, see Figure 5.

[0059] In order to prevent the material to be discharged from flowing into the filter element of the second filter pin 18 in the initial position, the filter pin 18 is moved axially to the blocking position, in which the cylindrical end portion of the second filter pin 18 blocks the fork leading to the inlet channel 3 of its pin socket 5, see Figure 6.

[0060] If filter pins 7 and 18 are in the starting positions shown in Figures 6 and 7, the system can be started, wherein any melt or fluid entering the filter element 1 is discharged through the discharge channel 10 of filter pin 7. The discharged material may flow out of the front discharge outlet 11 or drip without contaminating the housing 2.

[0061] If the material is not suitable for further processing, the manufacturing process or the established filtration can be initiated by pulling back or moving the filter pin 18 back to the operating position using the axial drive 17, as shown in Figure 8. This allows usable fluid to flow directly through the filter element 9 of the second filter pin 18 and feed to the outlet channel 4, and thus to subsequent processing.

[0062] Simultaneously or subsequently, the filter pin 7 can be moved away from its starting position by first rotating the filter pin 7 again until the discharge channel 10 is no longer connected to the inlet channel 3. Specifically, the rotary drive 14 can rotate the filter pin 7 again until the filter element 9 is properly rotated and aligned so that the fluid from the inlet channel 3 can be filtered during subsequent axial movement.

[0063] If the filter pin 7 is rotated back, see Figure 9, the axial drive 17 can move the filter pin 7 axially to release the coupling 24, see Figure 10, and then the rotary drive 14 can move back to its waiting position, see Figure 11.

[0064] Finally, the filter pin 7 can be moved axially back to its operating position so that the material to be filtered can flow through the two filter pins 7 and 18 again or be filtered by the two filter pins 7 and 18, see Figure 12. [Simplified Explanation of the Diagram]

[0036] The invention will be explained in more detail below with the aid of preferred embodiments and associated drawings. Illustrations: [Figure 1]: Perspective view of a filter device in the form of a filter replacement device with two filter pins in a filter housing, wherein the two filter pins are shown in their operating positions. [Figure 2]: Perspective view of the filter device of Figure 1, wherein one of the filter pins is shown in its filter replacement position for replacing the filter. [Figure 3]: Perspective view of the filter device according to the aforementioned figure, wherein the two filter pins are in their operating positions and the rotary actuator for rotating the lower filter pin is moved to its coupling position. [Figure 4]: Perspective view similar to the filter device of Figure 3, wherein the lower filter pin is axially moved to its coupling position to couple to the rotary actuator. [Figure 5]: Perspective view similar to the filter device of Figures 3 and 4, wherein the rotary actuator has rotated the lower filter pin to move to the starting position. [Figure 6]: Perspective view similar to the filter device of Figure 5, wherein the upper filter pin is moved to the blocking position so that the material to be separated is discharged only through the lower filter pin. [Figure 7]: Based on the perspective view of the filter device in the aforementioned figures, material is discharged through the discharge channel in the lower filter pin. [Figure 8]: Perspective view of the filter device after the start-up process, wherein the upper filter pin has moved back to its operating position. [Figure 9]: Perspective view of the filter device similar to Figure 8, wherein the lower filter pin has moved back to its operable rotatable position by means of the rotary drive. [Figure 10]: Perspective view of the filter device similar to Figure 9, wherein the lower filter pin has moved to its operating position and the rotary drive has been decoupled. [Figure 11]: Perspective view of the filter device similar to Figure 10, wherein the decoupled rotary drive has moved back to its waiting position. [Figure 12]: Perspective view of the filter device similar to Figure 11, wherein the lower screen screw has fully retracted to its operating position.

Claims

1. A filtering device for filtering a plastic melt (S), comprising: a housing (2) having an inlet channel (3) and an outlet channel (4); and a filter pin (7) disposed between the inlet channel (3) and the outlet channel (4) and housed in a pin socket (6) of the housing (2) in an axially displaceable and rotatable manner, wherein the filter pin (7) has a filter portion (8) with a filter element (9) and a discharge channel (10), wherein in an operating position of the filter pin (7), the filter element (9) is disposed in a filter portion (8) with a filter element (9) and a discharge channel (10). The filter section is disposed between the inlet channel (3) and the outlet channel (4) and connects the inlet channel (3) to the outlet channel (4). In one of the starting positions of the filter pin (7), the discharge channel is flowably connected to the inlet channel (3) and passes through the filter element (9) to one of the discharge outlets (11) of the filter pin (7). The filter pin (7) is characterized in that it presents different rotational positions in the pin socket (6) on the one hand in the operating position and on the other hand in the starting position, wherein the outer circle of the filter pin (7) is located One of the inlet ports (12) of the circumferential discharge channel (10) is located in one circumferential segment of the filter pin (7), the inlet port (12) being rotatably offset relative to the inlet channel (3) of the housing (2) in the operating position of the filter pin (7), and configured in the starting position of the filter pin (7) to overlap with the inlet channel (3), wherein the filter pin (7) has a filter replacement position in which the filter device (9) is freely accessible for replacement and / or extends axially out of the housing. Body (2), wherein the filter pin (7) presents at least substantially the same rotational position in its operating position and in its filter replacement position, wherein, viewed axially, the starting position of the filter pin (7) is located between the operating position and the filter replacement position, wherein the axial adjustment range of the filter pin (7) from the operating position to the starting position is shorter than the axial adjustment range from the starting position to the filter replacement position, such that the filter element (9) is still disposed within the housing (2) in the starting position.

2. The filter device of claim 1, wherein the filter pin (7) can be moved from the operating position to the filter replacement position by axial displacement without rotation and / or without approaching the rotational position of the starting position, and / or conversely, from the filter replacement position to the operating position.

3. The filter device of claim 1, wherein a rotary drive (14) is provided for rotating the filter pin (7) in the pin socket (6) and / or adjusting it independently of one of the axial directions of the filter pin (7) when the filter pin (7) is axially stationary.

4. The filter device of claim 3, wherein the rotary drive (14) is configured to be decoupled from the filter pin (7), and the filter pin (7) is axially movable between its operating position and filter replacement position when decoupled from the rotary drive (14).

5. The filter device of claim 4, wherein the filter pin (7) can be coupled to and decoupled from the rotary drive (14) by axial displacement of the filter pin (7), in particular in such a way that the rotary drive can be moved to a coupled position in the operating position of the filter pin (7) or in the filter replacement position and the filter pin (7) can subsequently be moved axially to a coupled position.

6. The filter device of claim 1, wherein the rotary drive (14) has an adjustment actuator (16) having an effective direction oriented transversely to the longitudinal axis of the filter pin (7) and at least substantially parallel to the tangent of the filter pin (7).

7. The filter device of claim 1, wherein the rotary drive (14) and an axial drive (17) for axial adjustment of the filter pin (7) are disposed on the same side of the housing (2), preferably the side of the housing (2) opposite to the housing side for filter replacement, wherein the filter pin (7) is viewed axially, and the rotary drive (14) is particularly disposed between the housing (2) and a pressure cylinder of the axial drive (17) for axial adjustment of the filter pin (7).

8. The filter device of claim 1, wherein the rotational offset of the filter pin (7) between its operating position and its starting position is between 20° and 120°, or between 30° and 90°, or between 30° and 60°.

9. The filter device of claim 1, wherein the discharge outlet (11) of the discharge channel (10) is disposed in one end portion of the filter pin (7), the end portion protruding from the housing (2) in the starting position of the filter pin (7).

10. The filter device of claim 1, wherein the discharge channel (10) is opened on one end face of the filter pin (7) by means of its discharge outlet (11).

11. The filter device of claim 1, wherein at least in the starting position of the filter pin (7), the discharge channel (10) is configured in a continuously inclined manner to the discharge outlet (11).

12. The filter device of claim 1, wherein the discharge channel (10) has a cross-section that increases continuously or gradually in the discharge direction, particularly configured to increase in a conical shape toward the discharge outlet (11).

13. The filter device of claim 1, wherein the discharge passage (10) extends through an axial column that bridges the filter portion (8) of the filter pin (7) in an exposed manner and preferably contains a longitudinal central axis of the filter pin.

14. The filter device of claim 1, wherein a second filter pin (18) is axially displaceable and housed in a second pin socket (5) in the housing (2), wherein the inlet channel (3) and the outlet channel (4) of the housing (2) are each configured in a bifurcated manner such that the inlet channel (3) can be selectively flow-connected to the outlet channel (4) individually via each filter pin (7, 18) or both filter pins (7, 18) together.

15. The filter device of claim 14, wherein the second filter pin (18) has an initial position in which the inlet channel (3) is disconnected from the outlet channel (4), and the inlet channel (3) is flow-connected to the periphery of the housing (2) only via the discharge channel (10) in the first filter pin (7).

16. The filter device of claim 15, wherein a control device is provided for axial adjustment of the two filter pins (7, 18), and the control device is configured such that, in order to set the starting position of the filter device (1), the first filter pin (7) is changed to its starting position by axial displacement and rotational adjustment and the second filter pin (18) is changed to its starting position only by axial adjustment.

Images