Patent Abstract:
A device for mixing two paste like compounds, such as a dental molding compound using a catalyst for the acceleration of polymerization. The housing has a mixing area with at least two inlet openings for the compounds and an outlet opening for the mixed compound. The device also has a mixing element that is disposed in the mixing area and propelled around a longitudinal axis. The housing has a coupling section that is situated in front of the mixing area with two coupling openings for connecting with two dispensing openings of a device for dispensing the two paste like compounds. The first and second ducts connect to the couplings via the coupling openings extending through the coupling section into the inlet openings for the mixing area. The two ducts are formed so that the first duct requires a greater time of entry of the compound into the mixing area than the time required for the second compound flowing through the second duct.

Full Description:
BACKGROUND 
     The invention relates to a device for mixing two paste-like compounds for a dental-molding compound and a catalyst for the acceleration of polymerization. The device has a housing, which has a mixing area with at least two inlet openings for the two paste-like compounds and an outlet opening for the mixed paste-like compound. The device also has a mixing element that is arranged so that it can be especially propelled in the mixing area and is pivotable in the housing along its longitudinal axis. The housing also has a coupling section that is situated in front of the mixing area with two coupling openings for connecting with two dispensing openings of a device for dispensing the two paste-like compounds. A first and a second duct connect to the coupling openings, extending through the coupling section to the inlet opening for the mixing area. The two ducts are formed so that the time needed for the entry of the paste-like compound into the coupling opening of the coupling section, until the entry into the inlet opening of the mixing area of the housing, is greater for the first duct than for the second duct. 
     The device is attached to the two outlet supports of a delivery device, wherein the compounds to be mixed are inserted into the mixing device by applying pressure to the compounds. After these compounds are mixed in the mixing device, they are dispensed from this device as one compound. 
     In numerous technical application areas it is necessary to apply two separately stored paste-like compounds in a mixed form. Here either a dynamic or a static flow mixer is used such as a mixer with a moveable or stationary mixing element, which mixes the compounds with each other while flowing through the mixing housing. 
     A dynamic mixer is known from U.S. Pat. No. 5,249,862. This known device has a mixer housing that is essentially tube-shaped with a pivotable mixer element arranged in it. The mixer element has a number of radially protruding rib-like mixer arms that rotate around the flow of compounds, and thus mixes the two paste-like compounds with each other when the mixer element is driven. The paste-like compounds reach the mixer element via a radial front wall at the back end of the mixer housing. Thus, the front wall has two inlet supports, which are attached to the outlet supports of the device for yielding the paste-like compounds. 
     However, regardless of whether a static or dynamic mixer is used, the above devices encounter problems because of the uneven flow of the different mixing components and thus the uneven amounts of the components in the mixing region. 
     It is already known that the problem can be constructively dealt with by having the base component or components within the mixer that tend to overdose flow a longer way to the mixer element than the other component or catalyzing components. This flow is between the reserve receptacle and the mixer. A first example for such a concept is described in DE-U-298 18 499, according to which the duct of the one component runs in the form of an arch around the longitudinal axis of the pivotable mixer element between the inlet of a dynamic mixer to the actual mixer area. An example for solving the problem in the case of a static mixer is given in U.S. Pat. No. 6,135,631, whereby this mixer was already on the market before the application date of the subject of DE-U-298 18 499, and was freely distributed and disbursed to third parties. Also for these known static mixers, the base component that tended to overdose was redirected in an arch-like form in the mixer, and the flow of compounds was divided in two, to reach the stationary mixing element next to the compound flow of the other component or other catalyzing component. In so doing, the introduction of the non-advancing (catalyzing) component flows as directly as possible, i.e. without any detours that would increase the flow resistance. Further examples for such mixers which delay the advancement of faster flowing compounds serving as dead volume are known from U.S. Pat. No. 5,487,606, and EP-A 0664 153. 
     In the case of the known mixers, a recontamination can occur after the deploying process ends, such as when the application device is shut off. This can occur because the base component flows into the container of the catalyzing component due to the varying pressure in the reserve receptacles of the paste-like compounds. If these components mix with each other and polymerize or harden in the deploying duct of one of the reserve receptacles of the paste-like compounds, the entire reserve receptacle and its content are unusable. 
     The present invention provides an additional device for mixing two paste-like compounds, whose mixing ratio is constant from the beginning of the dispensing of the mixed compounds, and also prevents a recontamination of these two compounds. 
     SUMMARY OF THE INVENTION 
     Thus, this device includes two ducts which are formed so that at least the first duct has a first segment that extends from the coupling opening in an axial direction of the mixer element, and a redirecting section that is connected to this. There is also a second segment leading to the associated inlet opening, whereby the axes of the first and second segments lie on a common level with the longitudinal axis of the mixer element. 
     Moreover, in addition to this, the two ducts are formed so that at least the first duct has a segment that extends from the coupling opening in the form of an arch around the axis of the mixing element. A second segment is provided which is placed in axial direction of the mixing element to the first segment, and leads to the associated inlet opening. There is a redirection segment that connects the first and the second segment. The redirection segment is arranged further away from the coupling opening, and serves as the inlet opening. 
     Basically, the temporary initial excess of the prescribed dosage or overdosage of one of the two components or compounds is compensated for by a corresponding form of the duct through which this compound flows until it arrives at the mixer element. This compensation occurs so that the paths, and thus also the retention periods vary the time the paste-like compounds need from the entry into the coupling openings of the coupling section of the mixer housing, to the entry into the inlet openings of the tube-shaped section of the mixer housing. It can be determined, from a study of the overdose amount and, if need be, of the flow speeds of both of the components to be mixed, how to form one of the two or both ducts by changes, such as via cross sectional changes, or form and size changes, as well as changes in length of the duct or ducts, so that both components simultaneously arrive in the inlet openings of the tube-shaped section of the mixer housing. 
     Beyond that, the invention also overcomes this problem by providing a second duct that has an extension section that lengthens the path between the coupling&#39;s opening and the associated inlet opening. This lengthening or extension section in certain areas, can be in the form of an arch around the longitudinal axis of the mixer element. In addition, the lengthening section has a first segment extending from the coupling opening in an axial direction of the mixer element, and a redirection section connected to this section, and a second segment that leads to the associated inlet opening, whereby the axes of the first and the second segments lie at a common level with the longitudinal axis of the mixer element. The lengthening section can extend, for example, 90° or 45° around the longitudinal axis of the mixer element in the form of the second duct that runs in an arch shape around the longitudinal axis of the mixer element. The occurrence of recontamination could also be avoided, even with an arch-shaped redirection of only approximately 5°. The entry of the (catalyzing) component in the mixer area is delayed by redirecting the paste-like compound in the second duct. To prevent an underdosage of the (catalyzing) component in the initial phase, the path of in the first duct can be lengthened, or by increasing the corresponding time which the paste-like (basis) compound requires from its entry in the coupling opening of the coupling section to its entry in the inlet opening of the mixer area of the housing. The redirecting in the second duct at the same time, increases the flow resistance in the second duct to prevent a recontamination by the base compound flowing into the second duct from the first duct, which would otherwise occur at the end of the deploying process, for example, when the application device is shut off. Thus, a mixing and hardening (polymerization) of the two components consequently cannot occur in the area upstream from the coupling opening, which is the device that dispenses the two paste-like compounds. 
     To compensate for the overdosage of one flow of compounds, the (first) duct assigned to this compound is designed to have a longer flow than the other (second) duct. This lengthening is achieved by extending the pertinent duct initially from the inlet opening of the coupling section of the mixer housing in the axial direction of the mixer element, or is formed as an arch around the axis of the mixer element. This duct is then a redirected preferably 180° and extends subsequently in the axial direction of the mixer element, or in the form of an arch around the axis of the mixer element, so that it ends, after being redirected 90° to 180° in the inlet opening of the mixer area. This form of the duct saves space while still providing a tolerable flow resistance. At the same time, as a result of these designs of the duct, the inlet opening of the mixer area is situated close to the coupling opening. When the coupling openings are arranged at 180° to each other, the inlet openings lie far from each other so that this recontamination is prevented. Moreover, the increased flow resistance in the other or second duct can be compensated for by this duct design where the duct includes a lengthening section to avoid any recontamination. 
     The duct formed in accordance with the invention can also be divided into two or several duct segments respectively that are basically parallel or, in particular, with regard to their path, formed the same. In other words, the coupling section of the housing of the mixer in accordance with the invention has ducts of various lengths that lead to the entry openings of the tube-shaped housing section. Alternatively, the two ducts can also have a varying sized dead volume, which is designed in accordance with fluid mechanics so that the compound only continues to flow in the direction of the inlet opening assigned to the pertinent duct, only after filling the pertinent dead volume. Instead of furnishing both ducts with dead volume, it is also possible to form only one of the two ducts with a dead volume. 
     In practice, mixers that are attached to two outlet supports of an application device are arranged at intervals to each other, to function properly. The mixer housing has thus in its coupling section, two coupling openings, which are axially staggered to the mixer element, and arranged diametrically opposite to each other. The inlet openings of the tube-shaped section of the mixer housing for the known mixers also lie, as a rule, diametrically opposite one another. Thus, for the known mixer designs, short ducts result between the coupling openings and the inlet openings assigned to them. The redirecting of at least one (or base) compound along segments of the first duct occurs so that ducts of varying lengths can be formed with such a mixing concept, whereby the axis of the first duct lies at a common level with the axis of the mixer element, or is in the shape of an arch around the longitudinal axis. 
     The arrangement of the segments of the first duct are formed so that the longitudinal axes of the segments together with the longitudinal axis of the mixer element span a joint radial level, and has the advantage of providing a space-saving form of the longer first duct. The segments of the first duct are preferably formed linearly. Alternatively, it is also possible that the ducts can be formed curvilinear or curved. However, in this case the curved longitudinal axis are arranged in turn in a joint radial level together with the (linear) longitudinal axis of the mixer element. 
     In the case described above, in which the segments of the first duct are formed linearly, it is furthermore advantageous if they run parallel to each other. The redirecting section is formed U-shaped in this case, for example, extending over 180°. 
     If the segments of the first duct extend in the form of an arch around the longitudinal axis of the mixer element, for example, they are formed over each other in an axial direction, wherein the redirection section is formed C-shaped, or it extends over 180°. In so doing, the compound flows at first in the first segment in the shape of an arch away from the coupling opening, and after redirecting, led back toward the inlet opening, which preferably lies near to the coupling opening. This design of the first duct is particularly space saving. 
     The inlet openings of the two ducts into the mixing area can lead axially or radially into the mixer element. An additional redirection section can still be connected to the second segment whichever form of the alignment of the inlet openings is used. This additional redirection section extends by 90° when the two segments of the first duct are aligned parallel, if the inlet openings discharge radially into the mixing area. This redirection extends over a total of 180° if the inlet openings discharge axially into the mixing area. 
     In another embodiment, the mixer element has at least one redirection element for support of the transport of the paste-like compounds in axial direction. These compounds arrive through the inlet openings into the tube-shaped section of the housing. At this point, the redirection element has a redirection surface that extends around the axis and runs inclined to the radial level of the axis. In this embodiment, compounds are fed radially in the essentially tube-shaped section of the mixer housing. Thus, the tube-shaped section of the housing has two radial inlet openings that are disposed diametrically opposite one another. The flows of paste-like compounds, which are inserted by applying pressure into the mixer, encounter at least one redirection element that extends around the axis of the mixer element within the tube-shaped section of the housing. This redirection element rotates with the revolving mixer element, and has a redirection surface that runs diagonally to the radial level of the axis. In other words, at least one redirection element has an essentially saw-tooth-shaped wedge that bends around the axis of the mixer element. This redirection element functions like a conveying screw for a spiral pump, and ensures that the upcoming paste-like material is directly transported in the axial direction from the inlet openings toward the outlet opening. Thus, recontamination continues to be prevented since the redirection element supports the axial feeding of the paste-like compounds arriving through the inlet openings in the tube-shaped section of the mixer housing. 
     The redirection element can have a wedge form. Alternative to this wedge form, the redirection element can be formed as a ridge that runs in the shape of a helix around the axis. In this embodiment, the redirection element thus has the form of a screw thread. These circumferential ridges are known from spiral pumps and conveying screws. 
     Two redirecting elements are advantageously arranged on the axis at the level of the radial inlet openings of the mixer area of the housing. The redirecting elements are diametrically arranged opposite to each other. These redirecting elements or every redirecting element extends preferably across an angular range of 180° to 90°. 
     The housing has an insertion aligned transversely to the axis on its back end, from which two inlet supports protrude. These inlet supports connect the mixer to the two outlet supports of a squeezing device. The insertion is in a conically widened section of the housing that is connected to the mixer area. It has two ducts that extend from the inlet supports. These two ducts run under, bending radially in a concentric cylindrical intake recess on the inner side of the insertion, by which the axis of the mixer element is taken in with at least the one redirecting element. Thus, the cylindrical intake recess of the insertion forms a subarea of the mixer area. The two inlet supports of the insertion form the couplings openings, and are connected to the outlet supports of the delivery or squeezing device. Thus, it is possible that the outlet supports are connected to the inlet supports. 
     However, unlike the previous embodiments, the two ducts extend then to the mixer element. Thus, the duct which extends from that inlet support, through which the compound material flows with the overdosage, at the beginning of the operation of the delivery device, is divided into two or more partial ducts that preferably at first, extend in the circumferential direction around the cylindrical intake recess, in two or more of these inlet openings, assigned respectively to these partial ducts. 
     The form of the mixer is such that several ducts extend from one or both coupling openings. The ducts end in several inlet openings, which discharge particularly uniformly in the section of the mixer housing with the mixer element. In addition to the improved fluidic performance of the paste-like compounds, it has the advantage that the materials admitted into the mixing area can be better and more homogeneously mixed. The spatially distributed insertion of each of the two compounds or at least of one of the two compounds, contributes to this because this distributed insertion of both compounds or at least of one of the two compounds in the mixer area has the advantage that a sort of premixing takes place through the portioning of the compounds flow into several inlet openings. 
     The individual partial ducts can be of the same or different length. They can be formed in the shape of a collective duct departing from the related coupling opening. Several diverging ducts branch off from the collective duct and they end in the inlet openings. 
     This concept of the spatially distributed feeding of the flows of compounds in the mixing area is applicable independent of whether the inlet openings are now arranged radially or axially. In other words, the normal lines of the opening cross sections of the inlet openings can be arranged both in the direction of the longitudinal extension of the mixer element, and also radially. 
     Also, the concept described above of the constructive design of the mixer, provides that both of the compounds arrive at the same time in the mixer area despite a possible occurrence of excessive flow rate of one of the two compounds, especially at the start of the material delivery. This result can likewise be achieved independent of whether the normal lines of the inlet openings run radially or parallel to the mixer element, or in another angle to it. 
     The invention has the benefit that several mixer arms are in the tube-shaped housing section between the radial inlet openings and the axial outlet opening. These arms protrude like a type of radial ribbing from the axis, and reach close to the inner surface of the tube-shaped housing section. These mixer arms are arranged within several radial levels from the shaft, and lead to a redirecting of the compounds flows that extend axially through the housing. Thus the desired mixing occurs through this. The mixing effect is further strengthened if these mixing arms, which due to their radial alignment, prevent the direct flow between the inlet openings and the outlet opening, and extend to a larger angular range, for example 90°. This can be achieved if adjacent mixer arms are connected to each other by a circumferential segment. In this way, therefore, mixer arms result that are formed like a type of quarter circles, whereby it can also be favorable if these quarter circles in their middle sections, as viewed in the circumferential direction, are more distant from the inner surface of the tube-shaped section of the housing in relation to their ends. It is practical if, from a first radial level to a second radial level, offset in the circumferential direction, two adjacent radial running mixer arms are respectively connected to each other in the way described above. 
     In addition to the rigid mixer arms, it is also advantageous for the thorough mixing process if the mixer element has additional flexible wiper elements, which sweep along at the inner wall of the tube-shaped housing due to their flexibility, or at least on the basis of their flexibly formed free end, are spaced from the axis. Alternatively, the wiper elements can also be formed rigidly and be tangentially distant from the axis of the mixer element. Two arranged rigid wiper elements are then arranged diametrically opposite to two different radial levels of the mixer element. Finally, it is also possible to provide for flexible and rigid wiper elements jointly at the mixer element. 
     In a further advantageous embodiment of the invention, the mixer arms of the adjacent first radial levels, which are in the axial direction to the inlet openings of the tube-shaped section of the housing, are shorter than the mixer arms in the remaining second radial levels. Thus, the distance between the radial outlying ends of the mixer arms to the tube-shaped housing section within the first radial levels is greater than within the second radial levels. This leads to a larger mixer area in the area of the tube-shaped housing section, which connects to the inlet openings. This larger mixing area has the advantage that dosage tolerances conditioned by the squeezing or delivery device are better compensated. The material component moving ahead has a longer retention period in the mixing area through the additional arrangement of the tangentially distant wiper elements within this enlarged mixing area. Through this, more time is available for mixing the slower material component with the material component moving ahead. 
     A larger mixing area in the area described before is however advantageously achieved when the axis of the mixer element is smaller in diameter than the remaining area, and the mixer arms extend radially, precisely as far as all other mixer arms, namely directly to the inner side of the tube-shaped housing section. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other objects and features of the present invention will become apparent from the following detailed description considered in connection with the accompanying drawings which disclose the embodiments of the present invention. It should be understood, however, that the drawings are designed for the purpose of illustration only and not as a definition of the limits of the invention. 
       In the drawings, wherein similar reference characters denote similar elements throughout the several views: 
         FIG. 1  is a side cross sectional view of a delivery device for mixed components; 
         FIG. 2  is a cross sectional view of a dynamic mixer wherein the dynamic mixer is used as a delivery device for the embodiment shown in  FIG. 1 ; 
         FIG. 3  is a cross-sectional view of the mixer shown in  FIG. 2  taken along the line III—III; 
         FIG. 4  is a cross-sectional view of the mixer shown in  FIG. 2  taken along the line IV—IV; 
         FIG. 5  is a cross sectional view of the mixer shown in  FIG. 2  taken along the line V—V; 
         FIG. 6  is a cross-sectional view of the mixer shown in  FIG. 2  taken along the line VI—VI; 
         FIG. 7  is a cross sectional view similar to the view shown in  FIG. 6 , showing an alternative form of the mixer element; 
         FIG. 8  is a longitudinal sectional view through the dynamic mixer shown of  FIG. 2  being used with the delivery device shown in  FIG. 1 ; and 
         FIG. 9  is a view of the back wall of a dynamic mixer according to a third embodiment, wherein the mixer is being used with the delivery device shown in FIG.  1 . 
     
    
    
     DETAILED DESCRIPTION 
     Referring in detail to the drawings,  FIG. 1  shows a delivery device  10  that is displayed in a side view for two paste-like components that are to be mixed with one another. Device  10  comprises a squeezing part  12 , and a mixer part  14 , whereby squeezing part  12  has two pressure tanks  16 , and  18  for receiving tubular bags  20 , and  22  containing the two paste-like compounds. At the forward frontal ends  24 , and  26  of pressure tanks  16 , and  18 , these dispensing openings have outlet supports  28 , and  30 . By applying pressure to the back end of tubular bag  20 , and  22  its contents are delivered through outlet supports  28  and  30 . The pressure impact of tubular bag  20 , and  22  occurs via pressure pistons  32 , and  34 , which are driven by a motor not shown. 
     A dynamic mixer  36  is attached to outlet supports  28 , and  30 . Dynamic mixer  36  is shown in  FIGS. 2-7 . Dynamic mixer  36  has a motor that drives mixer element  38 . Mixer element  38  can be coupled with a driving bar  40  that is rotatably driven by a motor that is also not shown. It is possible in the same way to attach a mixer  36 ′ or  36 ″ shown in the  FIGS. 8  or  9  to outlet supports  28 , and  30  of device  10 . 
     Dynamic mixer  36  is shown in greater detail in FIG.  2 .  FIG. 2  shows a longitudinal cut through mixer  36 . Mixer  36  has a housing  42  that comprises an essentially cylindrical or tube-shaped section  44 , which defines a mixer area  45 , in which mixer element  38  is arranged. Moreover, housing  42  has a conically widened coupling section  46  connected to tube-shaped section  44 . Conically widened coupling section  46  is turned toward squeezing part  12  at a back end. Mixer  36  also has a tapered forward end  50  opposite this back end  48 . Tapered forward end  50  is formed as outlet supports and defines outlet opening  52  for the material mix, while at back end  48  of housing  42 , two inlet supports  54 , 56  are arranged that form coupling openings  55  and  57  and can be attached to outlet supports  28 , and  30  of squeezing part  12 . Between two inlet supports  54 , and  56  is an opening  58 , in which one end  60  of mixer element  38  is pivoted. Driving bar  40  can be coupled with mixer element  38  through this opening. 
     Inlet supports  54 , 56  and opening  58  are formed by an insertion  62  that is inserted at back end  48  of housing  42  in its conical coupling section  46 . Departing from inlet supports  54 , and  56 , two ducts  64 , and  66  extend through insertion  62 . These two ducts  64 , and  66  meet through a redirection in radial openings  68 , and  70 . These inlet openings  68 , and  70  are radially arranged with regard to section  44  of housing  42 . The two paste-like components are delivered into dynamic mixer  36  through ducts  64 , and  66 . There the paste-like components meet in the radial direction of mixer element  38 . 
       FIGS. 2 and 3  show that insertion  62  has an intake recess that is central and essentially cylindrical. This intake recess is arranged concentric to opening  58  and inserted in mixer element  38 . Inlet openings  68 , and  70  are inserted in cylindrical wall  71  of intake recess  69 . Furthermore, ducts  64 , and  66  are also formed in this area. These ducts  64 , 66  are formed as grooves open above, or notches, which together with the essentially conically widened coupling section  46  form a duct closed on all sides. 
       FIG. 2 , shows first duct  64  is divided into several diversely running sections. Thus, first duct  64  has a first segment  59  that connects to coupling opening  55 . First segment  59  extends in an axial direction of mixer element  38 . At the end of this first segment  59  is a U-arch-shaped redirecting section  63 , which gives way to a second linear section  65 . From this, it goes through a further redirecting section  67 , which is essentially a 90° arch, before ending in inlet opening  68 . Two segments  59  and  65  extend parallel to each other, whereby their two parallel longitudinal axes run in a joint radial level to longitudinal axis  72 . The special essentially S-shaped form of first duct  64  is formed by an interaction between housing  42  and a protruding wall element  73  of insertion  62 . 
     Duct  64  extends first in the direction of outlet opening  52  and afterwards is redirected in order then to run back toward the back end of mixer  36 . This design is a direct route instead of the second duct  66  departing from its coupling opening  57  and flowing directly radially into inlet opening  70 . Thus, duct  64  can be given a longer length than duct  66 . Thus, in other words, a dead volume results due to the additionally created duct volume, which first has to be filled so that the flowing compound can flow further into the inlet opening  68 . Thus overdosages of the compound flowing through this duct can be corrected. 
     Mixer element  38  has a pivoted axis  72 , from which four rib shaped mixer arms  74 , and  75 , respectively, essentially radially protrude in a multitude of radial levels. The exact arrangement of these mixer arms  74 , and  75  results from the sectional view according to  FIGS. 4  to  6 . A limiting lateral edge of mixer arms  74 , and  75 , which lies in the circumferential direction, runs essentially tangentially to the peripheral surface of axis  72 . Furthermore as viewed from the flow direction, first mixer arms  74  are shorter than second mixer arms  75  arranged turned toward outlet opening  52 . Thus, the radial distance out from mixer arms  74  to inner surface  76  of tube-shaped section  44  is thus greater than in the case of mixer arm  75 . Thus, viewed from the flow direction of the compound, a mixing area section within housing  42  follows inlet openings  68 , and  70 . This mixing area section is larger than the mixing area section, in which longer mixer arms  75  are arranged. Between adjacent radial levels of mixer arms  74 , moreover, tangentially protruding wiper elements  77  are arranged, which contribute to an improvement of the mixing. The larger first section of the mixer area with regard to volume, moreover, assures that, as needed, the one leading compound also has a longer retention period in the mixer area, so that enough time remains for the other slower flowing compound to mix homogeneously with the compound first mentioned. 
       FIG. 2  shows a variation of the mixer which is indicated with dashed lines. With this variation, axis  72  is thinner in the area of the first radial level than within the remaining radial levels. Mixer arms  74 , and  75  have all the same extension, namely, directly contiguous to housing section  44 . 
       FIG. 4  shows four mixer arms  74  that are disposed on each radial level. Mixer arms  75 , reach according to  FIG. 3  to a region contiguous to inner surface  76  of housing section  44 . The total area between inlet openings  68 , and  70  and the end of mixer element  38 , extends to tapered end  50  of housing  42 . In addition, mixer element  38  has mixer arms  78  formed like a quadrant. These mixer arms  78  are formed by connecting two adjacent mixer arms  74  in a radial level. In this embodiment, the radially outlying limiting edge of mixer arm  78  is formed in the shape of circular arc, while it runs with the alternative according to  FIG. 7  secantially.  FIG. 7  shows mixer arm  78 ′ which therefore has in a middle circumferential section a larger distance to inner surface  76  of housing section  44 . 
     As shown in  FIG. 7 , mixer arms  74 ,  78 , and  78 ′ assure a redirecting and thus turbulence of the axially flowing paste-like compounds due to their radial extension close to housing section  44  with the rotation of mixer element  38 , mixer element  38  has three redirecting elements  80  in the area of the radial inlet openings  68 , and  70  that are arranged uniformly offset by 120° to each other and are formed like a type of conveying screw. Redirecting elements  80  are formed as sawtooth-shaped wedges that extend to approximately 60° around axis  72  of mixer element  38 . As shown in  FIG. 2 , redirecting elements  80  have a redirecting surface  82  that rises in the circumferential direction. Redirecting surface  82  points toward outlet opening  52  of dynamic mixer  36  and runs angled to a level radial to axis  72 . These redirecting elements  80  run therefore sectionally in the form of a helix and assure an axial movement component of the paste-like compound flows along longitudinal axis  72 . Thus, redirecting elements  80  support the delivery of the paste-like compound, which enters from inlet openings  68 , and  70  into housing section  44 . This supporting and thus strengthening discharging of the paste-like compound in the axial direction reduces the danger of contamination of the two paste-like compounds, which is the undesired mixing or recontamination of the two paste-like compounds through inlet opening  68 , and  70  in ducts  64 , and  66  possibly further in outlet supports  28 , and  30 . If there is a contamination and thus a polymerization in these areas, the residual material that may still be in tubular bags  20 , and  22  can no longer be delivered due to stoppage of outlet supports  28 , and  30 . Diverging from the illustration in  FIG. 2  redirecting elements  80  can be formed in so that at least its back end in the movement direction extends along sufficiently far in mixer area  45  in the direction of outlet opening  52  of dynamic mixer  36  so that this extends to both inlet openings  68 , and  70 . The flow of compounds delivered through inlet openings  68 , and  70  for improving the mixing and reducing a recontamination can be cut off for a short time or at least reduced. 
     In addition to redirecting elements  80 , mixer element  38  has two wiper ribs  86  that lie diametrically opposite each other. These ribs are spaced radially from axis  72  of mixer element  38  and run parallel to axis  72 . Wiper ribs  86  move with little clearance within along cylindrical wall  71  of insertion  62  while mixer element  38  is rotating. These wiper ribs contribute to an overall homogeneous thorough mixing of the two compound flows.  FIG. 2  shows two wiper ribs  77  that connect two mixer arms  74  that lie diametrically opposite each other within the first radial level of mixer arms  74 . This radial level connects to inlet openings  68 , and  70 , with the end of mixer element  38  arranged in opening  58  of insertion  62 . 
       FIG. 6  shows a further characteristic of dynamic mixer  36  wherein mixer arms  74  are rigid, essentially radially protruding ribs, which lead to a turbulence of the compound flows due to the rotation around axis  72 . In addition to rigid mixer arms  74 , and  75  and wiper elements  77 , dynamic mixer  36  can have further mixer arms  86  formed like thin flexible ribs, which wipe from within along inner side  76  of housing section  44 . These additional flexible mixer arms  86  assure a turbulence of the compound flow. One of flexible mixer arms  86  per level exists in several consecutive radial levels of mixer element  38 , whereby these mixer arms  86  are arranged around a constant angular range offset from one radial level to another radial level. The same is true for mixer arms  78  or  78 ′, which connect two adjacent mixer arms  74 , and  75  with each other and likewise are arranged in this case displaced offset from each other by 90° from radial level to radial level. These mixer arms  86  and mixer arms  78  or  78 ′ are therefore arranged uniformly distributed along a helix around axis  72 . Both mixer arm types are excellent for a homogeneous mixing of the paste-like compounds in dynamic mixer  36 , which also can be characterized as a flow path mixer. 
     Dynamic mixer  36 ′ shown in  FIG. 8  essentially corresponds to mixer  36  shown in FIG.  2 . The form of first duct  64  with a first segment  59  that connects to coupling opening  55  and extends in an axial direction of mixer element  38 , with a U-shaped redirecting section  63  and with a second linear segment  65  corresponds approximately to the design of first duct  64  according to the embodiment according to FIG.  2 . For this, a wall element  73  is formed in insert  62  that runs essentially parallel to longitudinal axis  72  of mixer  36 ′. 
     Thus a second duct  66 ′ of dynamic mixer  36 ′ is also furnished with a first segment  88  that is connected to coupling opening  57 . Segment  88  extends in the axial direction of mixing element  38 . At the end of this first segment  88 , is a U-arch-shaped redirecting section  89  that leads to a second linear segment  90  and from this, leads through an additional redirecting section  91  that is essentially a 90° arch and ends in inlet opening  70 . Redirecting section  89 , second linear segment  90  and additional redirecting section  91  together form a lengthening section lengthening the way from coupling opening  57  to inlet opening  70 . Two segments  88  and  90  extend parallel to each other, whereby their two parallel longitudinal axes run in a common radial level to longitudinal axis  72 . The special form of second duct  66 ′, which is essentially S-shaped, is achieved in interaction between housing  42  and a protruding wall element  92  of insertion  62 . 
     Duct  66 ′ is given a greater length and the flow resistance is increased because duct  66 ′ first extends in the direction of outlet opening  52  and afterwards is redirected, so that it then runs back in the direction of back end  48  of mixer  36 ′. Consequently, there is a reduction in the danger of contamination of the two paste-like compounds, which results from undesired mixing or recontamination of the two paste-like compounds through inlet openings  68 , and  70  in ducts  64 , and  66 ″ and may be further contaminated in the outlet supports. If there is a recontamination in these areas and thus a polymerization of the compounds, the residual material that may still be in the tubular bags can no longer be delivered, as mentioned above, due to the stoppage of the outlet supports. 
     The greater length of duct  66 ′ is however compensated by the design of duct  64  described above, so that the compounds arrive through ducts  64  and  66 ″ simultaneously via inlet openings  68  or  70  in mixer area  45 . 
     A further embodiment of a dynamic mixer  36 ″ is shown in  FIG. 9 , as seen from its back end  48 . Tube-shaped section  44  of housing  42  and mixer element  38  included in it corresponds essentially to the form described in  FIGS. 1-8 . The form of the ducts, which extend from coupling openings  55  and  57  to inlet openings  68 , and  70 , diverge in this embodiment. 
     For example, first duct, which extends between coupling opening  55  and inlet opening  68  is divided into two partial ducts  64 ′, and  64 ″, which extend in opposite directions in the form of an arch around longitudinal axis  72 . Both partial ducts  64 ′, and  64 ″ have a first segment that connects to coupling opening  55 . First segment extends about 45° around longitudinal axis  72 . At the end of this first segment is a U-arch-shaped redirecting section, which leads to a second arch-shaped segment that extends essentially in the axial direction underneath the first segment. The two segments of partial ducts  64 ′, and  64 ″ can then lead to a common inlet opening  68  or into two inlet openings separate from each other. The redirection between the first and second segments occurs at about 180°, so that the partial compound flows in partial ducts  64 ′, and  64 ″. These ducts  64 ′ and  64 ″ are at first directed in the form of an arch away from the coupling opening  55  and after the redirecting in a offset level are led back to inlet opening  68  or inlet openings, which are arranged in the vicinity of coupling opening  55 . 
     With this design partial ducts  64 ′, and  64 ″ are given a greater length, so that additional duct volume results. The additional duct volume must first be filled so that the compound can flow into inlet opening  68 . Both compounds enter therefore approximately at the same time in mixer area  45 . 
     Second duct  66 ″, which extends from coupling opening  57  to inlet opening  70 , also runs in the shape of an arch along longitudinal axis  72 . In the embodiment shown in  FIG. 9 , the flowing compound is redirected in second duct  66 ″ by about 5° around longitudinal axis  72 . It is however also possible, to achieve other, in particular larger, redirections around longitudinal axis  72 . It is also still possible to also form second duct  66 ″ with two partial ducts that extend in the opposite direction in the form of an arch around longitudinal axis  72 . 
     The length of second duct  66 ″ is insignificantly greater as a result of the redirecting in second duct  66 ″, while the flow resistance in second duct  66 ″ however clearly increases. The danger of a recontamination is considerably reduced through this design. 
     Inlet openings  68 , and  70  of the two compounds advantageously lie nearly diametrically opposite one another in the embodiment shown in FIG.  9 . The path that a compound must cover before a recontamination can occur, exits from one inlet opening into the inlet opening of the other compound, which lies essentially opposite it, is consequently chosen to be as large as possible. The danger of recontamination is thus further reduced. 
     The designs of the first and second ducts shown in the examples can of course be combined with each other in any way desired. It is therefore possible to provide an arch-shaped redirecting of the first duct and an axial redirecting of the second duct. In the same way, an arch-shaped redirecting of the second duct can also be achieved with an axial redirecting of the first duct. 
     Accordingly, while at least one embodiment of the present invention has been shown and described, it is to be understood that many changes and modifications may be made thereunto without departing from the spirit and scope of the invention as defined in the appended claims.

Technology Classification (CPC): 1