Abstract:
A pig handling device has a housing, a cavity found in the housing in which a pig can be received, a connection by means of which the cavity is connectable to a processing system, the connection suitable for allowing the pig to pass through, and a handling element that is arranged in the cavity, influences the mobility of the pig in the cavity, and has a base element and a functional element. The base element has a first surface, and the functional element is connected to the base element in the cavity and has a second surface. The arrangement improves cleanability in that the handling element has a concavely curved transition surface arranged between the first surface and the second surface and having a core curvature region, and in that the base element and the functional element are bonded to one another outside of the core curvature region.

Description:
TECHNICAL FIELD 
     The disclosure relates to a pig handling device. 
     BACKGROUND 
     There is a general requirement to minimize product losses in modern production systems, in particular in the milk and food industry, in the beverage industry as well as in the personal and health care industry. Moreover, the standards for the waste water quality of such systems are increasing. This is counteracted with the use of so-called pigging systems, with which a cleaning body that is named pig is moved through the pipeline system of the production system in order to push out valuable, free-flowing products without mixing with other media from the pipelines. Pig handling devices serve to automate this process step. 
     Such a pigging station, in which a pig is stored and can be automatically released into the pipeline system at the desired point in time, is introduced in WO 1995/033952 A1. This publication improves cleanability of the pigging station with improvements geared towards the holding of the pig in the station and enables in particular a better cleaning of the pig. Through a holding with play, the mobility of a pig in the cleaning agent flow is achieved such that the complete surface of the pig is cleaned. A further aspect in the igging station described therein is the dead-space-free design of the wall of the interior space of the station, in particular through an interior space contour shaped in a flow-suitable manner. 
     A pigging station through which a product can flow, which is designed as a sending and receiving station, is shown in DE 101 44 860 A1. Therein, it is suggested to provide two connections arranged coaxially to each other and designed so that the pig can pass through. The mobility of the pig within the pigging station is monitored by an adjustable catch bracket. Disadvantageous deviations of the product flow are avoided and the cleanability is enhanced. 
     DE 94 12 043 U1 suggests a pigging station in which the pig is fixable in its position, which can be flowed around, by two controllable stops. In addition to a first pipeline connection, the station has a second, laterally attached pipeline connection. The goal is to reduce dead spaces and to thus improve the product flow through the pigging station. 
     A device for catching a ball moving within a pipeline is suggested in DE 1 775 03 A. The device has a part that is detachable by means of a pusher valve, in which the ball is received. The goal is to be able to remove the ball from the pipeline in a simple and secure manner. 
     SUMMARY 
     The teachings herein describe a pig handling device with improved device cleanability. 
     Embodiments of the invention are based on the rationale of including additional parts of the device for pig handling into consideration in addition to the pigging surface and the interior space contour. Handling elements with which the movements of the pig in this interior space are influenced in a targeted manner are located in the interior space of the device. A handling element is generally made of several parts due to its size. The design of a handling element built from a base element with a first surface and a functional element with a second surface is described herein. 
     A concavely curved transition surface is arranged with a core curvature region between a first surface and a second surface, wherein the functional element and the base element are bonded to one another outside of the core curvature region. In particular in the case of surfaces converging at an angle, a concave transition surface creates an easy-to-clean surface of the handling element so that attached grime can be reliably removed. The surface connection lies outside of the region, in which the first and second surfaces converge at an angle. The surface region of a surface connection is as smooth as possible in order to ensure a reliable cleanability. In this connection, the arrangement of the surface connection outside of the curvature region is very advantageous because a smooth surface of the surface connection can be established in a technically reliable and cost-effective manner. The cleanability of the pig handling device is improved over the prior art through the measures according to the invention. 
     According to a further development, this advantage is even greater when the first and second surfaces converge at an angle of less than 135° and the core curvature region has a curvature radius of at least 6.35 mm. 
     Another further development suggests arranging the transition surface on the base element and thus simplifying the functional element. Moreover, a material savings is enabled, for example in a rod-like functional element. 
     An embodiment of the invention can be further developed in that the base element comprises a receiving cavity, in which the functional element is received in sections in a guided manner, wherein it is then surrounded by a section having the transition surface. A very good orientation of the base element and the functional element with respect to each other is hereby achieved before the surface connection is established. 
     A further development relating to the transition surface arranges it on the functional element. The orientation is hereby facilitated before the establishment of the surface connection because a force directed towards the surface connection can be introduced near the surface connection. Moreover, the transition surface can be used to expand the functional element on the adhesive connection, and thus also improve the orientation. 
     According to another further development, the handling element is designed as a guiding arrangement, wherein the base element is connected with the housing, and the functional element for guiding the pig is designed at a radial distance from a wall surface delimiting the cavity. This advantageously prevents the pig from attaching to the wall surface. Transitions from the pig surface to the wall surface that are susceptible to contaminants and that are acute-angled are hereby prevented. 
     According to one embodiment, the functional element can comprise at least one rod, whereby the contact of the functional element and the pig necessary for the handling of the pig takes places with a small contact surface. Moreover, geometrically simple and thus easily cleanable surfaces are created. 
     The cleanability of the device can also be simplified in that the base element is designed as one piece with the housing of the device. Transition points between components, which are difficult to work on, are hereby avoided in order to ensure good cleanability. 
     According to another further development, the handling element is formed as a gripping structure. The base element is thereby designed as a fastening head, to which the functional element designed as one or more rods shaped like a gripping arm is attached. Such a handling element permits the handling, in particular delimitation, of the pig movements in the axial and radial direction in a simple and reliably cleanable manner. This fastening head can act as a stopper in the axial direction. 
     This further development can be improved with respect to a technically simple automation through a pressurizing-medium-driven gripper drive. The fastening head is shiftable with the gripper drive. 
     According to another further development, the device has in its interior space, in addition to the first handling element, a second handling element. One of the first handling element or the second handling element is designed as a guiding arrangement as described above and the other as a gripping structure as also described above. On one hand, this improves the guidance and handling of the pig and ensures good cleanability of the device through the design of the guiding arrangement and gripping structure described above. 
     The further development just described is improved when the guiding arrangement and the gripping structure are designed so that the pig can be received in it with play. The formation of permanent contact points is thereby prevented and a cleaning of all surface parts is ensured. 
     The device can comprise a shiftable stopper, with which the pig in cooperation with the handling element is held securely in the cavity, for example in the case of strong cleaning flows. 
     A cost-effective automation of the device is given with the help of a pressurizing-medium-driven stopper drive, with which the stopper is shiftable. 
     The device can comprise a second connection, which is arranged such that a fluid flow flowing around the pig located in the cavity is designable. The pig and the handling element(s) in the fluid flow are hereby reliably cleaned. A particularly good cleaning of the handling element and the pig results in cooperation with the play described above. 
     A further improved cleanability of the device is achieved when all wall surfaces of the housing converging at an angle of less than 135° and delimiting the cavity transition into each other with a transition radius of at least 6.35 mm. 
     The invention shall be explained in greater detail based on an exemplary embodiment and its further developments and the representation of the effects and advantages will be covered in greater detail. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a cross-section through a device for pig handling with a pig located inside the device. 
         FIG. 2  shows a cross-section through a detailed view F from  FIG. 1 . 
         FIG. 3  shows a cross-section through a detailed view G from  FIG. 1  in a second design. 
         FIG. 4  shows a cross-section through a detailed view G from  FIG. 1  in a third design. 
         FIG. 5  shows a cross-section through a detailed view G from  FIG. 1  in a fourth design. 
         FIG. 6  shows a cross-section through a detailed view G from  FIG. 1  in a fifth design. 
         FIG. 7  shows a cross-section through a detailed view H from  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows, in a cross-sectional representation, a device  2  for handling a pig  4 . The device  2  has a housing  10  with a cavity  16 , which is bordered by a lateral wall surface  22 , a sloping wall surface  24  and a rear wall surface  26 . 
     A first connection  12  is provided on the housing  10  and allows the connection of the device  2  with a pipeline of a pipeline system of a production system. The pig  4 , which can enter or exit the cavity  16  through the first connection  12 , is receivable in the cavity  16 . The first connection  12  is set to the diameter of the pig  4 , in particular with respect to its inner diameter. The diameter of the pig  4  is in turn set to the inner diameter of the pipeline of the production system, because in order to remove product from the pipeline as effectively as possible, these diameters differ only slightly from each other. 
     A second connection  14  is provided on the housing  10 . With its help, the device  2  can be installed in the production path of the production system. The product flows through the device  2  during production. When the product needs to be removed from the production system with the help of the pig  4 , a driving medium is let into the device  2  through the second connection  14 , which subsequently pushes the pig  4  through the production system. Moreover, the second connection  14  is used to let the cleaning agent into the cavity  16  of the device  2 . 
     A first handling element is designed as a gripping structure  30 . This gripping structure  30  has a fastening head  32  as the base element, to which a ring of gripping arms  34  is attached, wherein the gripping arms  34  each represent a functional element. The gripping arms  34  are designed such that they prevent the pig  4  from moving freely in the direction of the first connection  12 . The fastening head  32  acts as a stopping means in order to restrict the movement of the pig  4  away from the first connection  12  in the direction towards the rear wall surface  26 . 
     The gripping structure  30  has a gripper rod  36 , which penetrates a rear part  20  of the housing  10 . 
     The gripper rod  36  and the rear part  20  of the housing  10  are sealed by means of a seal  42  in order to separate the cavity  16  from the surrounding area of the device  2 . The gripper rod  36  works with a gripper drive  40 , which can move the gripping structure  30  in a straight-line movement back and forth along a movement direction B. The gripper drive  40  is designed as a pressurizing-medium-driven drive. With the help of the gripper drive  40 , the gripping structure  30  can be moved towards the rear part  20  of the housing  10  in order to bring the pig  4  into an idling position. The gripping structure  30  can be moved in the direction of the first connection  12 , in order to bring the pig  4  into a sending position, in which it can be removed from the device  2  and moved into the pipeline by the propellant. This movement can perform a phase of the product recovery. 
     A second handling element is designed as a guiding arrangement  50 . The guiding arrangement  50  has a base element  52 , which is designed as a ring with a mainly rectangular cross-section. This ring is connected with the rear part  20  of the housing  10 . In order to ensure good cleanability, the ring is preferably sunk flush in the rear part  20  so that its surface is evenly closed off with the rear wall surface  26 . In a further development, the base element  52  is designed as one piece with the rear part  20  of the housing  10 . 
     Several guide rods  54 , which extend along the movement direction B, are fastened on the base element  52 . They form a cage, which prevents the contact of the pig  4  and of the lateral wall surface  22  in each position of the gripping structure  30  and of the pig  4 . Moreover, several stop rods  56 , which have an end section  58  bent towards the gripper rod  36 , are provided on the base element  52 , preferably in a circular arrangement. These end sections  58  form a stop for the pig  4  when the gripping structure  30  is located in the position pulled back from the rear part  20 . 
     The device  2  has a further retaining element with which the pig  4  can be held in the cavity  16 . A stopper  60  penetrates the wall of the housing  10  and protrudes from the lateral wall surface  22 . A seal  64 , which seals the wall surface  22  and the stopper against each other and thus permanently separates the surrounding area of the device  2  from the cavity  16 , is located at the penetration point. The stopper  60  is operatively connected with a stopper drive  62 . With the help of the stopper drive  62 , the stopper  60  can move in a straight-line movement far enough into the cavity  16  such that the pig  4  can no longer get to the first connection  12 . The stopper  60  can be pulled far enough back with the stopper drive  62  so that the pig can reach the pipeline from the cavity  16  and through the first connection  12 . 
       FIG. 2  shows one design option for a detailed area F of  FIG. 1 . The fastening head  32  of the gripping structure  30  is shown in the partial cross-section of each area, in which a gripping arm  34  is connected with the fastening head  32 . The fastening head  32  has a first surface  70 , while the gripping arm  34  has a second surface  72 . In a three-dimensional room, the first surface  70  mainly forms a cylinder. The second surface  72  is also a cylinder in the shown area of the gripping arm  34 , which sits perpendicularly on the cylinder of the first surface  70 . The smallest angle, at which the first and second surface  70  and  72  converge three-dimensionally, is a marked angle W. Angle W is a right angle in this example. A section  78  protruding from the first surface  70  is provided, which has a receiving cavity  80 . The section  78  surrounds the gripping arm  34 , and the receiving cavity  80  receives the gripping arm  34  in a form-fitting manner. 
     The first surface  70  and the second surface  72  merge into each other by means of a transition surface  74 . The transition surface  74  is concavely curved and has a core curvature region  76  with a curvature radius K. The core curvature region  76  is that part of the transition surface  74  in which the curvature is clearly pronounced. The curvature of the transition surface  74  transitions into the curvature of the first surface  70  or second surface  72  outside of the core curvature region  76 . According to a further development, the curvature radius K is at least 6.35 mm. 
     The gripping arm  34  and the fastening head  32  are bonded to one another. The surface connection is arranged outside of the core curvature region  76  so that the transition from the first surface  70  and the second surface  72  is not located in a region with a strong surface curvature. This is advantageous because the curvature only needs to be executed on one component and can be established in a particularly exact manner. Moreover, it is avoided that the transition surface  74  is uneven in its particularly curved region due to the surface connection. This is advantageously in relation to production and cleanability. 
     A simple form of the surface connection well suited for use in the food and fine chemical industries is a welded seam  82 . This is realized around the gripping arm  34  and is located on the free end of the section  78 , at which end the transition surface  74  transitions into the second surface  72 . 
     The transition from the second surface  72  to the transition surface  74  can have a slight step, as shown. A sloping transition between the second surface  72  and the transition surface  74  can be created through a welded seam in a welding process with a welding filler material. The welded seam can be polished or smoothed in order to improve its dirt-repelling properties. 
     In  FIG. 1 , the connection between the stop rod  56  and the base element  52  is realized in the same manner as the connection of the gripping arm  34  and the fastening head  32  explained based on  FIG. 2 .  FIGS. 3-6  show further design options for the detailed area G. 
       FIG. 3  shows a cut through the mainly annular base element  52  with a first surface  70 ′. The base element  52  has a section  78 ′, which rises on the first surface  70 ′ and has a blunt end  84 . The mainly cylindrical stop rod  56  with a second surface  72 ′ sits with its end  86  on the blunt end  84 . The first surface  70 ′ and the second surface  72 ′ form an angle W′ of 90 degrees. 
     The concavely curved transition surface  74 ′, which creates a transition from the first surface  70 ′ into the second surface  72 ′, is provided on the section  78 ′. The transition surface  74 ′ is provided with a core curvature region  76 ′. The core curvature region  76 ′ has a curvature radius K′, which is preferably at least 6.35 mm. The blunt end  84  of the base element  52  and the end  86  of the stop rod  56  are bonded to one another outside of the core curvature region  76 ′. This surface connection can be established through welding, as is the case with the connection of the fastening head  32  and gripping arm  34  in  FIG. 2 . This design has a particularly smooth transition from the second surface  72 ′ into the transition surface  74 ′. Welding procedures without the use of welding filler material can be used. 
     The design according to  FIG. 4  deviates from that according to  FIG. 3  as follows. The stop rod  56  has on its end a pin extension  88 . In a cylindrical rod, the pin extension  88  can be a rod section with a reduced diameter. The pin extension  88  is received in a form-fitting manner and completely in a receiving cavity  80 ′. It is conceivable to further develop the form fit such that the stop rod  56  cannot turn in the receiving cavity  80 ′. 
     The receiving cavity  80 ′ is provided in the section  78 ′ and can extend up to into the base element  52 . Through the complete receiving of the pin extension  88 , the second surface  72 ′ of the stop rod  56  and the transition surface  74 ′ located on the section  78 ′ of the base element  52  hit each other and form a common surface, which can advantageously be designed in a flush manner. The surface connection in the form of a welded seam  82 ′ between the base element  52  and the stop rod  56  is established at the transition from the second surface  72 ′ into the transition surface  74 ′ and is located outside of the core curvature region  76 ′. 
     Special advantages of this design lie in the easily producible smooth transition from the second surface  72 ′ into the transition surface  74 ′ and the simplified orientation of the base element  52  and the stop rod  56  with respect to each other before the surface connection is established. 
       FIG. 5  shows in cross-section a further exemplary embodiment for the connection of the base element  52  and the stop rod  56  from the detail G in  FIG. 1 . The stop rod  56  has a foot  90 , which has a cross-section expanded with respect to the stop rod  56 . The stop rod  56  has the second surface  72 ′, which transitions seamlessly into the transition surface  74 ′, and has a core curvature region  76 ′ with a curvature radius K′. The transition surface  74 ′ is located on the foot  90 . The foot  90  is received in a form-fitting manner by a recess on the base element  52  and is thereby sunk in the base element  52  such that the transition surface  74 ′ transitions in a preferably flush manner into the first surface  70 ′ of the base element  52 . A welded seam  82 ′ for creating a surface connection of the base element  52  and the stop rod  56  is provided at the transition point and outside the core curvature region  76 ′. In the example shown, the angle W′ between the first surface  70 ′ and the second surface  72 ′ is right-angled. Depending on the design of the guiding arrangement  50 , a smaller or larger angle W′ may be necessary. A special advantage of this exemplary embodiment is the large diameter of the welded seam  82 ′, which has advantages both for the orientation of the components with respect to each other before the surface connection is established as well as for the load capacity through leverage forces acting on the stop rod  56 , for example parallel to the first surface  70 ′. 
       FIG. 6  shows in cross-section an enhancement of the embodiment just described. An end of the stop rod  56  with the second surface  72 ′ has an enhancement in the form of a foot  90 . On the side of the foot  90  lying opposite the stop rod  56 , the foot  90  has a pin extension  88 . The pin extension  88  and the foot  90  are received in a recess of the base element  52 . The mainly cylindrical second surface  72 ′ transitions into the concavely curved transition surface  74 ′, which has a core curvature region  76 ′ with a curvature radius K′. It is advantageously at least 6.35 mm. The foot  90  and the pin extension  88  are received in the base element  52  up to a depth such that the transition surface  74 ′ transitions into the first surface  70 ′ with a step of a few tenths of a millimeter or less. The transition surface  74 ′ can also still have a slight curvature outside of the core curvature region  76 ′. The base element  52  and the stop rod  56  are bonded to one another outside of the core curvature region  76 ′ through a welded seam  82 ′. 
     The connections between the base element  52  and the stop rod  56  shown based on  FIGS. 3-6  are also applicable to the connection between the base element  52  and the guide rod  54 . 
     Furthermore, the design options for the transition from the first surface  70  and  70 ′ to the second surface  72  and  72 ′ shown based on  FIGS. 2-6  can be used interchangeably. The design shown for the transition at the gripping structure  30  can be used for the guiding arrangement  50  and vice versa. Here, the gripping arm  34  corresponds to the stop rod  56 , and the fastening head  32  corresponds to the base element  52 . 
     It is advantageous to apply the characteristics of  FIGS. 2-6  to all base elements  32 ,  52  and functional elements  34 ,  54  and  56  converging at an angle of less than 135° and located in the cavity  16 . 
       FIG. 7  shows in detail a section labeled with H in  FIG. 1 . The lateral wall surface  22  and the sloping wall surface  24  delimit the cavity  16  inside the housing  10 . The sloping wall surface  22  advantageously transitions into the first connection  12  with a rounded transition. The wall surfaces  22  and  24  hit each other at an angle V. In order to keep the installation length of the device  2  short, this angle V is less than 135°. A radius R of at least 6.35 mm is formed at the transition of the wall surfaces into each other so that this transition is easily cleanable. 
     A list of the reference numbers herein is included below.
       2  Device     4  Pig     10  Housing     12  First connection     14  Second connection     16  Cavity     20  Rear part of the housing     22  Lateral wall surface     24  Sloping wall surface     26  Rear wall surface     30  Gripping structure     32  Fastening head     34  Gripping arm     36  Gripper rod     40  Gripper drive     42  Seal (gripper)     50  Guiding arrangement     52  Base element     54  Guide rod     56  Stop rod     60  Stopper     62  Stopper drive     64  Seal     70  First surface     70 ′ First surface     72  Second surface     72 ′ Second surface     74  Transition surface     74 ′ Transition surface     76  Core curvature region     76 ′ Core curvature region   K Curvature radius   K′ Curvature radius     78  Section     78 ′ Section     80  Receiving cavity     80 ′ Receiving cavity     82  Welded seam     82 ′ Welded seam     84  Blunt end     86  End     88  Pin extension     90  Foot   B Movement direction   W Angle   W′ Angle   V Angle (housing)   R Transition radius   P Position   F View F   G View G   H View H