RU2455957C2 - Mixer - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: invention relates to field of medicine, in particular dentistry and is intended for mixing viscous-elastic two-component substances for dental prosthetic casts. Mixer contains: holding case, dynamic element of mixing and static device of mixing. Holding case on one end has, at least, one input hole for first component, and, at least, one input hole for second component, which will be mixed. Holding case additionally has output hole, located on the opposite end with respect to input holes and being with them in connection by flowing medium. Output hole is adapted for delivery of mixed substance. Holding case forms mixing chamber in its internal part. Dynamic element of mixing has, at least, one part, located in mixing chamber, made with possibility of rotational movement around its longitudinally passing axis and having ribs which overlap holding case to realise mixing of said two components. Static device of mixing is located farther after dynamic element of mixing in direction of supply of materials and contains specified quantity of elements, immovably fixed to holding case and having shape of part of Archimedean screw, in which material is forced to pass through it, rotating around longitudinal axis direction and additionally mixing two components before exit from mixer.

EFFECT: improvement of homogeneity of output components.

12 cl, 6 dwg

Description

The invention relates to a mixer, and more specifically, to a mixer that is both dynamic and static and suitable for mixing two components intended for composing a material for casting dentures.

It is known that currently there are devices widely available on the market for dispensing and mixing materials with two components, suitable for casting denture patient bridges.

In particular, the two constituent materials (base and catalyst) are contained in separate containers, such as, for example, plastic cylindrical elements.

The containers are compatible with a mechanism that allows for the appropriate delivery of materials by compressing pistons placed directly on the inside of the containers.

The mixer is connected to the openings of the containers by means of two inlets made on it and the shape of which corresponds to the inlet of the corresponding openings of the said containers, and also provided with a delivery channel from which the mixed material is discharged for subsequent use.

In particular, the mixer consists of a completely hollow body made of a plastic material, which at the end has said inlet openings for introducing the base and catalyst contained in the cylinders.

The mixer has a mixing chamber in which a rotating element is located, equipped with appropriate ribs to achieve optimal homogenization of the base and catalyst.

In particular, the rotating element has a driving shaft directly connected to the dispensing mechanism in such a way that the mechanism itself can simultaneously push materials to the mixer inlets in the desired quantities and volume ratios and can drive the rotating element provided with ribs.

The speed of rotation of the ribs, as well as the pressure exerted on the material, and thus on the feed rate, is so studied that an optimal base-catalyst mixture is provided that leaves the dispensing hole in the form of a homogeneous mass.

The prior art, briefly described above, is illustrated, for example, in EP 1274501 or EP 1368113 in the name of 3M ESPE.

The second document mentioned above discloses a dynamic mixer suitable for mixing especially viscous substances, including the use of a motion path well studied for materials entering the mixing chamber, in order to avoid cross-contamination and improve subsequent mixing. In addition, it is important to note that when known dynamic mixers are designed to work with highly viscous materials, the outlet opening is enlarged to reduce flow resistance.

In addition, a device for mixing and dispensing materials, such as binders or sealing materials, in which a first “static” component is provided and in which each of the material components is introduced separately and distributed while still separate from the other component, is known from EP 603492 lots of points to enter a true dynamic mixer.

From the feed region of the dynamic mixer, the materials begin to mix together through the Archimedean screw, driven around its axis.

EP 1029585, in contrast, shows the general configuration of a mixing device adapted to be used alternately with a static mixing screw, thereby forming a “static mixer”, or with a dynamic rotor within the mixing chamber to form a “dynamic mixer”.

As clearly described in the text, these two solutions are to be used alternately, and cannot be combined together.

Although the devices briefly described above are now widely marketed in many different ways, they however have some limitations and / or disadvantages.

It should be especially noted that the dynamic mixers currently known do not always allow optimal mixing of the base and catalyst.

In fact, if the viscosity of the material, the rotational speed of the dynamic element and the feed rate of the material directly within the mixer are not optimized, there is a risk of the material escaping in an inhomogeneous state, thereby causing subsequent problems during the manufacture of castings for denture bridges.

Obviously, as soon as the mixer has been optimized, changing the viscosity parameters necessarily entails poor-quality mixing of the components and a significant decrease in flow rate, especially if viscous materials are used.

Another negative aspect that is encountered primarily when working with the most viscous products is the formation of air bubbles in the mixed mass, which are the result of incorrect internal geometry of the mixer.

In addition, the dynamic mixer allows a fairly rapid passage of components through the mixing chamber and, therefore, to obtain an appropriate degree of mixing, the dynamic mixers must be made quite long or in all cases the mixers must have a minimum number of mixing ribs.

Finally, the dimensions of the mixing chamber affect the amount of material remaining inside the mixer after use, which is wasted.

Accordingly, the present invention is essentially directed to eliminating all of the aforementioned disadvantages.

The first objective of the invention is the manufacture of a mixer for viscoelastic materials that are used for the needs of prosthetics, which allows a homogeneous and optimal mixing of the base and catalyst.

Another objective of the invention is to avoid the formation of bubbles or other disadvantages of mixing in the mixing chamber and, thus, in the issued material.

An additional objective of the invention is to make a mixer, which allows to obtain satisfactory flow rates even with a significant increase in the viscosity of the products.

In addition, it is necessary that uniformity of the outgoing product is always ensured, even when there are significantly different levels of viscosity and consistency of the material.

An additional object of the invention is to reduce the length of the dynamic rotor and / or the number of ribs used, without adversely affecting, on the other hand, the functioning of the mixer.

An additional object of the invention is to reduce the amount of residual material in the mixer after use, thereby reducing material loss.

The invention also has the task of achieving lower production costs, while at the same time proposing the manufacture of a mixer compatible with dispensing devices of containers of materials currently on the market.

The above and additional objectives that will become more apparent in the course of the present description, essentially achieved by the mixer in accordance with the characteristics set forth in the attached claims.

Further, the features and advantages will be better understood from the detailed description of the preferred, but not exclusive, embodiments of a particular mixer for viscoelastic substances such as paste components for denture castings in accordance with the present invention.

This description will be set forth below with reference to the accompanying drawings, given by way of non-limiting example, in which:

Figure 1 is a longitudinal section of a mixer in accordance with the present invention;

Figa and 2b depict a dynamic rotor included in the device of the invention;

Figa, 3b and 3c depict the base of the mixer housing, which is visible in Fig.1;

Figa and 4b depict the outer casing of the mixer, which is visible in Fig.1;

5 depicts an alternative embodiment of a dynamic mixer in accordance with the invention; and

6 depicts an alternative embodiment of the base of the mixer housing.

With reference to the drawings, a mixer, especially adapted for mixing viscoelastic substances such as base and catalyst, which are components of pastes for denture castings, is generally indicated by the number 1.

Said mixer consists of a holding body 2 made of a generally transparent plastic material and formed of an external housing 15 and a base of the housing or cover 14, hermetically connected to the external housing.

As you can see, the base cover 14 has an inlet 3 for receiving a first component to be mixed, and a second inlet 4 for receiving a second component that is to be mixed.

In the depicted embodiment, these two components enter the mixer through the inlets 3, 4 having an axis parallel to the axis 8 of the mixer directly. It should be noted, however, that, alternatively, an inlet with an inclined axis transverse to the axis of symmetry 8 can also be provided.

As can be seen from Figure 1, the flow of components is then deflected, forcing them to enter the mixing chamber in the direction transverse to the axis of rotation 8. This deviation is, in particular, due to the presence of inclined lower surfaces 40 of the outer casing 15.

However, from the point of view of the entry directions and the gaze in FIGS. 3b and 3c, it can be seen that the incoming substances are directed perpendicular to the axis 8 of the mixer in a horizontal plane (directions C, D in FIG. 3c).

In more detail, the base cover 14 and the external housing 15 in cooperation form a preliminary chamber 41 for entry of components, which is configured to deflect the incoming flow from the direction parallel to the axis 8 of the mixer, to the direction at an angle to this axis, by means of inclined surfaces 40 and also radially directed (directions C, D) to the axis directly through channels 42, 43 of the corresponding shape.

Alternatively (FIG. 6), channels 42, 43 having a certain shape can be tilted in a plane so that these two components are directed toward the pre-chamber 41 in oblique directions and along opposite paths in the plane (directions C ′, D ′) ; in this way, mixing can be improved, which can be useful for use, in particular when fairly viscous substances are used.

Finally, it should be noted that the premixing chamber 41 is not connected to any of the ribs 12 that could introduce air bubbles during mixing.

In any case, the embodiment depicted in FIG. 6 also involves the direct entry of materials into the premixing chamber 41 without any delay, but simply providing two streams that move in opposite directions.

In this way, better mixing can be achieved under certain conditions, because the materials enter the mixing chamber with an optimal flow slope and velocities that are not necessarily parallel to axis 8.

The holding body 2, more precisely, the external housing 15 has a longitudinal extension starting from the first end 2a, where the base cover 14 is located, while the opposite end 2b, where the outlet 5 is formed, is adapted to the exit of the mixed material.

A mixing chamber 6 is formed in the holding body 2, in which two components introduced through the inlets 3, 4 are thoroughly mixed to the desired uniformity and then discharged through the outlet 5.

You can see the dynamic mixing element 7, part 7a of which, composed of a central rod 13 and a predetermined number of ribs 12 radially arranged around it, is rotatably rotated around its longitudinally extending axis 8 of the inner part of the mixing chamber 6.

For this purpose, the dynamic mixing element 7 is equipped with a lower nozzle 16 of a certain shape intended for engagement by means of a drive (for example, a corresponding shaft of rotation) that can rotate it. This drive means is not shown or described since it is a known type of device currently on the market.

More precisely, the dynamic mixing element 7 accommodates the first region 6a of the mixing chamber 6, generally having a cylindrical configuration with a constant channel section.

The strictly cylindrical sectional shape of the mixing chamber, however, is not necessary, but there may also be a section having a part which becomes wider or narrower towards the exit.

In addition, in the depicted embodiment, there is a tapering portion 20 (in the form of a truncated cone) connecting the first region 6a to the second region 6b of the mixing chamber 6.

Within the first region 6a, the ribs 12 are preferably arranged at different heights along the longitudinal axis 8 of the mixing element and in the appropriate quantity for each level (in the illustrated embodiment, four ribs are spaced 90 ° apart for each of the four levels) and extend from the central shaft 13 as far as the inner surface of the first region 6a of the mixing chamber allows, so that its cross section is substantially filled.

In particular, the ribs of the rotating shaft are divided as follows: the ribs of the first row are narrow, while the end ribs 21 are larger and in their upper part have scrapers 22 that almost touch the inner walls of the tapering part 20.

Alternatively, the adaptability of the truncated-conical central rod 13, which becomes larger from the base to the inlet (FIG. 5), can be ensured. This includes an additional narrowing of the free passage of the material flowing through it. Obviously, it is also possible that the truncated-conical Central rod 13 becomes narrower to the outlet 5.

As shown in the accompanying drawings, further downstream of the dynamic mixing element 7 along the material supply direction A, there is an additional static type mixing element 9 containing a plurality of shaped elements 10 adapted for additional subsequent mixing of the materials before they exit the mixer.

In particular, the static mixing element 9 is placed immediately downstream of the dynamic mixing element 7 and ends directly at the outlet 5.

Said element is fixedly attached to the holding body and, in particular, to the second region 6b of the mixing chamber 6.

It should be noted that the second region 6b has an average passage section smaller than the average passage section of the first region 6a. In general, the second region 6b also has a cylindrical configuration and will have a constant passage section.

It should also be noted that the static elements 10 of the device 9 form permanent channels for the material flowing through the mixer. These channels are directed across the longitudinal axis 8 of the device 9.

In addition, due to the sequential passage of the said material through such elements having a certain shape, the material is forced to move in directions transverse to one another along the supply path.

From a geometric point of view, the elements 10 of the static mixing device 9 contain a part of the Archimedean screw, in which surfaces force the material to pass through them, rotating around the axis of the mixer 8.

If there is more than one part of the Archimedean screw, they will deflect at an angle of 90 °.

Obviously, the number of these elements can be set depending on the viscosity of the material, the required degree of mixing to be obtained, the flow resistance produced by this static mixer and all other technical requirements on which these parameters depend.

For example, a mixer may be manufactured having one to four of said surfaces 10 having a specific shape.

Based on the above, the mixer in accordance with the invention operates as follows.

Each of the two components is forced by means of a dispensing mechanism to enter the mixer under pressure, through the first and second inlets 3, 4, having different sections of the passage in order to obtain the desired volumetric relations between the two products at the inlet. Here, the base and the catalyst are supplied to the first mixing step within the first three quarters of the chamber 6, the first mixing step being performed by a dynamic mixing element rotating about its axis 8. In the remaining quarter before entering the static mixer, due to the shape of the last mixing rib 21 and the flow resistance caused by the static element, mixing has a further improvement.

The material moves further from the inlets 3, 4 to the outlet 5 due to the pressure of the incoming material produced by the dispensing mechanism.

The material, after mixing in the chamber 6a by means of the dynamic mixer 7, is forced to pass through the second region 6b of the mixing chamber, where the static mixing device 9 described above, which performs the third additional mixing step, is located. Then the material leaves the outlet 5 so that it can be used.

The invention has important advantages.

First of all, it should be noted that the adaptation of the mixer, consisting of the first dynamic part and the second static part, improves the uniformity of the output material.

In fact, the static part of the mixer slows down the overall feed rate of the material, which is therefore required to stay in the dynamic mixing area longer.

Because of the above, the dynamic mixing element 7 can provide better homogenization of materials without the need for too long and / or too many ribs.

In addition to being an area acting as a “stopper”, that is, an area having the property of reducing the speed of the material, the static mixer has the ability to perform additional mixing, which further improves the properties of the outgoing material. Thus, due to the presence of this static mixing device 9, the mixer can also work with substances of different viscosities and in all cases obtain a good degree of mixing.

In addition, in contrast to the generally accepted opinion, the flow barrier at the end does not reduce its speed if appropriate techniques for improving the flow in other compartments of the mixer are applied.

The static element introduces a barrier, which, if properly studied, can improve mixing with a dynamic mixer and optimize the mixing operation that will be carried out directly in the final part of the mixer.

Finally, due to the presence of a smaller number of finer fin geometry, the heating of the material passing through the mixer is reduced, and, in addition, due to the smaller size of the mixing chamber, wasted material is also reduced.

Claims (12)

1. A mixer for viscoelastic two-component substances for denture castings, containing:
a holding body, which at one end has at least one inlet for the first component to be mixed, and at least one inlet for the second component to be mixed, and the holding body further has an outlet located at the opposite end relative to the inlet openings and being in fluid connection with them, the outlet being adapted to dispense a mixed substance, and the holding housing forms a mixing chamber in Oei inner portion;
a dynamic mixing element having at least one part located in the mixing chamber, made with the possibility of rotational movement around its longitudinally passing axis and having ribs overlapping the holding body, for mixing the two components;
a static mixing device, provided further downstream of the dynamic mixing element in the direction of supply of materials, and the static mixing device contains a predetermined number of elements having a certain shape, fixedly attached to the holding body and having the shape of a part of the Archimedean screw in which the material is forced to pass through it, rotating around the longitudinal direction of the axis and additionally mixing the two components before exiting the mixer. 2. The mixer according to claim 1, characterized in that the mixing chamber comprises a first region adapted to receive a dynamic mixing element and rotate it, and a second region adapted to receive a static mixing device, the first region having a middle passage section wider than constant cross section of the passage of the second region. 3. The mixer according to claim 2, characterized in that the second region has a cylindrical configuration and has a constant passage section, moreover, preferably the first region also has a cylindrical configuration and has a constant passage section, while these two regions are mutually connected by a tapering part. 4. The mixer according to any one of the preceding paragraphs, characterized in that the static mixing device is fixedly attached to the holding body, essentially blocking the entire area of the passage of materials. 5. The mixer according to claim 1, characterized in that the elements having a certain shape of the static mixing device form constant channels for the material, which are directed across the longitudinal axis of the device, said constant channels, in turn, forming mutually transverse directions for the material, flowing along the supply path of the material itself. 6. The mixer according to claim 1, characterized in that the static mixing device is located immediately along the dynamic mixing element and ends at the outlet. 7. The mixer according to claim 1, characterized in that the holding body forms a preliminary chamber, which is configured to deviate the flow of incoming material from a direction parallel to the axis in order to deflect it by means of inclined surfaces. 8. The mixer according to claim 7, characterized in that the preliminary chamber has channels of a certain shape to make these two components enter in opposite directions and trajectories. 9. The mixer according to claim 1, characterized in that the dynamic mixing element contains a predetermined number of ribs radially extending from the central rod, and the ribs are preferably located at different heights along the longitudinal axis of the mixing element. 10. The mixer according to claim 1, characterized in that the dynamic mixing element further comprises end ribs radially extending from the central rod, said end ribs having scrapers at their upper part, which substantially correspond in shape to the inner walls of the tapering part. 11. The mixer according to claim 1, characterized in that the dynamic mixing element comprises a central rod of a truncated conical configuration, preferably having a cross section that increases towards the outlet of the mixer. 12. The mixer according to claim 1, characterized in that the holding housing comprises an outer casing and a base cover sealed to the outer casing, the base cover being provided with said inlet openings that have different inlet sections to allow entry of said first and second components into given volumetric relationships.

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