MIXING DEVICE AND MIXING METHOD FOR DISPENSING A MULTI-COMPONENT POLYMERIC MIXTURE

Abstract

Mixing device (1) for dispensing a multi-component polymeric mixture, comprising a main body (2) comprising a mixing chamber (3) for mixing a first and a second component of the mixture, the mixing chamber having a main development along a longitudinal direction (100) and comprising a respective longitudinal open end (4); a movable body (5) having a central axis (101) with longitudinal development and slidably housed in the main body (2) to alternatively assume, by sliding along the longitudinal direction (100), an occlusion position of the mixing chamber (3) and a mixing position, wherein the movable body (5) comprises a first channel (6) and a second channel (7) each comprising a respective end portion (20) both displaced from the central axis (101) of the movable body (5) and developing substantially along the longitudinal direction (100) up to a longitudinal end face (8) of the movable body (5) facing the open longitudinal end (4) of the mixing chamber (3), wherein the respective end portions (20) of the first (6) and second channel (7) develop inside the movable body (5) or they are made by respectively a first (9) and a second groove (10) obtained on a longitudinal surface (11) of the movable body (5), each groove (9, 10) having development with a component perpendicular to the longitudinal direction (100).

Claims

1. Mixing device for dispensing a multi-component polymeric mixture, the device comprising: a main body comprising a mixing chamber for mixing at least a first and a second component of the mixture; the mixing chamber having a main development along a longitudinal direction and comprising a respective longitudinal open end; a movable body having a central axis with longitudinal development and slidably housed in the main body to alternatively assume, by sliding along the longitudinal direction, an occlusion position, in which it occludes the mixing chamber to preclude a mixing of the first and second component of the mixture, and a mixing position, in which it clears the mixing chamber to allow the mixing of the first and second component of the mixture, wherein the movable body comprises a first channel and a second channel each comprising a respective end portion extending substantially along the longitudinal direction up to a longitudinal end face of the movable body facing the longitudinal open end of the mixing chamber, wherein the respective end portions of the first and second channel are both displaced from the central axis of the movable body, and wherein the respective end portions of the first and second channel are made by respectively a first and a second groove obtained on a longitudinal surface of the movable body, each groove having development with a component perpendicular to the longitudinal direction or wherein the respective end portions of the first and second channel develop inside the movable body.

2. The device according to claim 1, wherein the development of each groove is a helical development, preferably with axis coinciding with the central axis, or wherein the respective end portions of the first and second channel developing inside the movable develop entirely along a straight path parallel to the longitudinal direction.

3. The device according to claim 1, wherein the respective end portions of the first and second channel are arranged at sides diametrically opposite to each other with respect to the central axis of the movable body.

4. The device according to claim 1, wherein the first and second channel develop inside the movable body for a whole longitudinal dimension of the movable body.

5. The device according to claim 1, wherein the first and second channel each comprise a respective inlet groove obtained on the longitudinal surface of the movable body connected to the respective end portion and arranged at longitudinally opposite side with respect to the longitudinal end face of the movable body, wherein the inlet grooves have rectilinear longitudinal development.

6. The device according to claim 5, comprising a first and a second feeding duct obtained in the main body and ending at the longitudinal surface of the movable body in communication with respectively the first and second channel, wherein the first and second feeding duct communicate with the inlet grooves of respectively the first and second channel.

7. The device according to claim 1, wherein the first second channel comprise a respective feeding portion which develops inside the movable body substantially along the longitudinal direction away from the longitudinal end face of the movable body and at longitudinally opposite side of the movable body with respect to the first and second groove, wherein the first and second channel coincide in a single feeding portion at the respective feeding portions, wherein the first and second channel each comprise a respective connecting duct between the single feeding portion and the first and second groove respectively, each connecting duct having development with at least one perpendicular component.

8. The device according to claim 1, wherein the first and second channel comprise a respective feeding portion made by a respective feeding groove obtained on the longitudinal surface of the movable body, each feeding groove developing away from the longitudinal end face of the movable body and at longitudinally opposite side of the movable body with respect to the first and second groove up to a longitudinal end of the movable body opposite to the longitudinal end face of the movable body.

9. The device according to claim 7, comprising, for each of the first and second component, a respective injection channel and a respective outlet channel obtained in the main body, and a first and a second recirculation groove made on the longitudinal surface of the movable body at diametrically opposite positions with respect to the central axis of the movable body to set in hydraulic communication, when the movable body is in the occlusion position, a respective injection channel-outlet channel pair, wherein the connecting ducts are in a more distal position from the longitudinal end face of the movable body with respect to the first and second recirculation groove.

10. The device according to claim 1, wherein each end portion of the first and second channel when internal to the movable body, or each inlet groove, is angularly arranged about the central axis of the movable body with an angle greater than or equal to 70°, and less than or equal to 110°, with respect to each of the recirculation grooves.

11. Mixing method for dispensing a multi-component polymeric mixture, the method comprising: arranging the mixing device according to claim 1; conveying a gas flow into the first and second channel; while keeping the gas flow active in the first and second channel: placing the movable body in the mixing position, mixing in the mixing chamber the first and second component of the multi-component polymeric mixture in order to make the multi-component polymeric mixture, and dispensing the multi-component polymeric mixture through the longitudinal open end of the mixing chamber; and subsequently moving the movable body to the occlusion position to clean the mixing chamber by mechanical scraping of the movable body and action of the gas flow, wherein the method comprises keeping the gas flow active for a substantially whole time interval in which the movable body is in the occlusion position.

12. The device according to claim 1, wherein the first and second channel develop parallelly to the longitudinal direction.

13. The device according to claim 7, wherein the single feeding portion develops along the central axis of the movable body.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0067] The features and the advantages of the present invention will be further apparent by the following detailed description of some embodiments, presented by way of non-limiting example of the present invention, with reference to the attached figures, in which:

[0068] FIG. 1 shows a perspective view of a partial longitudinal section of a first embodiment of the mixing device according to the present invention;

[0069] FIG. 2 shows a front view of the partial longitudinal section of FIG. 1 with the movable body in the mixing position;

[0070] FIG. 3 shows a perspective and partial section view of a portion of the movable body of the mixing device of FIG. 1;

[0071] FIG. 4 shows a front view of a perpendicular section along the plane 300 of the mixing device of FIG. 1;

[0072] FIG. 5 shows a perspective view of a partial longitudinal section of a second embodiment of the mixing device according to the present invention;

[0073] FIG. 5a shows a front view of a detail of a perpendicular section along the plane 200 of the mixing device of FIG. 5;

[0074] FIG. 6 shows a front view of a longitudinal section of a third embodiment of the mixing device according to the present invention;

[0075] FIG. 7 shows a front view of a longitudinal section of a fourth embodiment of the mixing device according to the present invention.

DETAILED DESCRIPTION OF SOME EMBODIMENTS OF THE INVENTION

[0076] In the present description and figures the same reference number is used for the same elements, also in their different constructive variants.

[0077] In the figures, number 1 globally indicates a mixing device for dispensing a multi-component polymeric mixture (not shown). Exemplarily the device 1 comprises a main body 2 comprising a mixing chamber 3 (FIG. 2) for mixing a first and a second component of the mixture (not shown, typically polyol and isocyanate so that the obtained mixture is a polyurethane mixture, e.g. a polyurethane foam).

[0078] Exemplarily the mixing chamber 3 has a main development along a longitudinal direction 100 and it comprises a respective longitudinal open end 4.

[0079] Exemplarily the device 1 comprises a substantially cylindrical movable body 5 having a central axis 101 with longitudinal development (exemplarily coinciding with the longitudinal direction 100) and slidably housed in the main body to alternatively assume, by sliding along the longitudinal direction 100, an occlusion position (e.g. shown in FIGS. 1, 4, 5, 5a, 6 and 7), in which it occludes the mixing chamber 3 to preclude a mixing of the first and second component of the mixture, and a mixing position (e.g. shown in FIG. 2), in which it clears the mixing chamber 3 to allow the mixing of the first and second component of the mixture. Exemplarily the central axis 101 is a central symmetry axis of the movable body 5.

[0080] Exemplarily the mixing chamber 3 is substantially counter-shaped to an envelope of the movable body 5 (e.g. neglecting possible grooves present), i.e. it is cylindrical.

[0081] Exemplarily the device 1 comprises, for each first and second component, a respective injection channel 13a, 13b and a respective outlet channel 14a, 14b obtained in the main body 2. Exemplarily the movable body 5 comprises a first 15a and a second recirculation groove 15b made on a longitudinal surface 11 of the movable body at diametrically opposite positions with respect to the central axis 101 of the movable body and extending along a respective purely longitudinal straight path. Exemplarily the recirculation grooves put in hydraulic communication, when the movable body is in the occlusion position, a respective injection channel-outlet channel pair.

[0082] Exemplarily the movable body 5 comprises a first channel 6 and a second channel 7 each comprising a respective end portion 20 developing substantially along the longitudinal direction 100 up to a longitudinal end face 8 of the movable body 5 facing the longitudinal open end 4 of the mixing chamber 3, wherein exemplarily the respective end portions 20 of the first 6 and second channel 7 are both displaced from the central axis 101 of the movable body and they are arranged at sides diametrically opposite to each other with respect to the central axis 101 of the movable body 5.

[0083] In a first embodiment, as exemplarily shown in figures from 1 to 4, the end portions 20 of the first 6 and second channel 7 are exemplarily made by a first 9 and a second groove 10 respectively obtained on the longitudinal surface 11 of the movable body 5, each groove 9, 10 having a respective helical development (e.g. with constant pitch) with axis coinciding with the central axis 101 of the movable body. In one alternative embodiment, the first and the second groove can have any development with a perpendicular component (e.g. not necessarily helical, but for example arc development extending on the longitudinal surface of the movable body).

[0084] Preferably the first 6 and second channel 7 comprise a respective feeding portion 50 which develops inside the movable body 5 parallelly to the longitudinal direction 100, away from the longitudinal end face 8 of the movable body and at longitudinally opposite side of the movable body with respect to the first 9 and second groove 10. Exemplarily (FIG. 3) the first 6 and second channel 7 at the respective feeding portions coincide in a single feeding portion 50 (only partially shown), developing along the central axis 101 of the movable body. In an alternative embodiment not shown, the feeding portions of the first and second channel are distinct and separate from each other.

[0085] Exemplarily (FIG. 3) the first 6 and second channel 7 each comprise a respective connecting duct 18, 19 between the respective (not shown), or the single, feeding portion 50 and respectively the first 9 and second groove 10, each connecting duct 18, 19 having a purely perpendicular development.

[0086] Exemplarily the connecting ducts are in a more distal position from the longitudinal end face 8 of the movable body with respect to the first 15a and second recirculation groove 15b so that the section of each, or of the single, feeding portion is not limited by the presence of the recirculation grooves (facilitating the passage of the gas flow).

[0087] In one alternative embodiment, (not shown) instead of the feeding portions made in the movable body as described above, the device comprises a first and a second feeding duct obtained in the main body and ending at the longitudinal surface of the movable body in communication with the first and second channel respectively. In this embodiment, the first and the second channel therefore coincide with the respective end portions made respectively by the first and second (helical) groove. In this embodiment, the first and second feeding ducts comprise a respective feeding end mouth facing the movable body in communication with the first and second groove respectively and having a circumferential development about the central axis of the movable body having a width equal to a perpendicular development of a projection on a perpendicular plane of a tract of respectively the first and second groove having a longitudinal length equal to an excursion of the movable body between the occlusion and mixing positions. In fact, given the development with a perpendicular component of the grooves, the portion of each groove instantaneously at, and in communication with, the respective feeding duct (i.e. with the respective feeding end mouth) undergoes a circumferential displacement about the central axis of the movable body during the longitudinal displacement of the movable body. The feeding end mouths, thanks to their circumferential development as described above, therefore always remain in communication with the respective groove for the whole longitudinal excursion of the movable body.

[0088] In a second embodiment, as exemplarily shown in FIGS. 5 and 5a, the end portions 20 of the first 6 and second channel 7 are made by respectively a first 9 and a second groove 10 obtained on the longitudinal surface 11 of the movable body 5, each groove 9, 10 having a respective helical development with axis coinciding with the central axis 101 of the movable body. Exemplarily the first 6 and second channel 7 each comprise a respective inlet groove 21 contiguous to the respective end portion 20 and arranged at longitudinally opposite side with respect to the longitudinal end face 8, the inlet groove being obtained on the longitudinal surface 11 of the movable body and exemplarily having rectilinear longitudinal development.

[0089] In the second embodiment, as shown in FIG. 5a, the device 1 comprises a first 16 and a second feeding duct 17 obtained in the main body 2 and ending at the longitudinal surface 11 of the movable body 5 in communication with the inlet grooves 21 of respectively the first 6 and second channel 7 to allow the communication between each duct and the respective groove against the longitudinal displacement of the movable body, without the need to circumferentially widen the feeding end mouth beyond the width of the respective groove, as in the embodiment described above.

[0090] In one embodiment alternative to the second embodiment (not shown), the first and second channel can comprise, instead of the feeding ducts 16 and 17, a respective feeding portion which longitudinally develops inside the movable body (as discussed with reference to FIG. 3).

[0091] In a further embodiment (not shown) the feeding portions of the first and second channel can in turn be made, instead of by means of an internal passage as discussed above with reference to FIG. 3, by a respective feeding groove obtained on the longitudinal surface of the movable body, developing away from the longitudinal end face of the movable body and at longitudinally opposite side of the movable body with respect to the first and second groove. The feeding grooves can, for example, develop up to a longitudinal end (not shown) of the movable body, opposite the end face 8, which is movably inserted into a chamber into which the gas is pressurized (to create a pair of passages of the gas).

[0092] In a third embodiment, as exemplarily shown in FIG. 6, the first 6 and second channel 7 exemplarily develop entirely inside the movable body 5 along a rectilinear path parallel to the longitudinal direction 100 and (not shown) for a whole longitudinal dimension of the movable body (i.e. the first and second channel are completely internal to the movable body and they are longitudinally passing through the movable body). In the third embodiment, the subdivision of the first and second channel into the respective end portions 20 and into the respective feeding portions 50 is purely arbitrary.

[0093] In the fourth embodiment shown in FIG. 7, exemplarily the respective end portions 20 of the first 6 and second channel 7 develop inside the movable body 5 and the first 6 and second channel 7 each comprise a respective inlet groove 21 obtained on the longitudinal surface 11 of the movable body and connected to the respective end portion, arranged at longitudinally opposite side with respect to the longitudinal end face and having a longitudinal rectilinear development (for example in a similar way to the second embodiment). Exemplarily the first and the second channel develop from the longitudinal end face 8 of the movable body up to a point on the longitudinal surface (i.e. the lateral surface) of the movable body, following an L-shaped path (with a respective tract 32 perpendicular to the longitudinal direction to connect each end portion 20 with the respective inlet groove 21). In a variant embodiment not shown, the first and second channel can extend, from the longitudinal end face 8 to the respective inlet groove 21, along a rectilinear path inclined with respect to the longitudinal direction.

[0094] In the fourth embodiment (for example in a similar way to the second embodiment) the device 1 exemplarily comprises a first 16 and a second feeding duct 17 obtained in the main body 2 and ending at the longitudinal surface of the movable body in communication with the inlet grooves 21 of the first and second channel respectively.

[0095] Exemplarily each inlet groove 21 (shown for the second embodiment in FIG. 5, not shown for the fourth embodiment), and each end portion 20 of the first 6 and second channel 7 internal to the movable body (third and/or fourth embodiment, not shown), is angularly arranged about the central axis 101 of the movable body with an angle equal to 90° with respect to each recirculation groove 15a, 15b.

[0096] In use, the mixing device 1 allows to perform a mixing method for dispensing a multi-component polymeric mixture, for example during a step of manufacturing of composite panels for applications in the automotive field.

[0097] Preferably the mixing device 1 is firmly fixed to an end of a robotic arm (e.g. a robotic arm with at least five axes, not shown) in order to be easily moved in the space for dispensing the mixture easily and/or with accuracy on a desired substrate.

[0098] Initially, it is exemplarily provided conveying the gas flow in the first 6 and second channel 7. Subsequently, with the movable body 5 in the occlusion position, it is exemplarily provided pushing under pressure the first and second components (not shown) into the respective injection channels to make them recirculate, by means of the recirculation grooves 15a and 15b, towards the respective outlet channels (in turn connected in closed loop to the respective injection channels, not shown).

[0099] At this point the device is ready to mix the components and dispense (e.g. by spraying) the obtained mixture.

[0100] Thus exemplarily, keeping the gas flow active in the first and second channel, it is provided placing the movable body in the mixing position, to mix in the mixing chamber 3 the first and second component of the multi-component polymeric mixture in order to make the multi-component polymeric mixture, and dispensing the multi-component polymeric mixture through the longitudinal open end 4 of the mixing chamber 3.

[0101] Exemplarily (FIGS. 1 and 2) the device comprises a nozzle 70 arranged downstream of the mixing chamber and shaped (not shown) to give to the dispensed mixture a jet having, for example, a laminar shape, advantageous for covering with the obtained mixture large surfaces of the substrate even with a few coats of the mixing device. The gas flow introduced into the mixing chamber through the first 6 and the second channel 7 exemplarily contributes to the dispensing of the mixture by spraying.

[0102] Subsequently, once ended the phase of spraying of the substrate, it is exemplarily provided, keeping the gas flow active in the first and second channel, moving the movable body to the occlusion position to clean the mixing chamber 3 by mechanical scraping of the movable body 5 and action of the gas flow. Exemplarily when the movable body is in the occlusion position, the longitudinal end face 8 of the movable body lies on a same plane of the longitudinal open end 4 of the mixing chamber so that the movable body, in its longitudinal displacement, entirely travels the mixing chamber to clean it.

[0103] Exemplarily the method comprises keeping the gas flow active for a whole time interval in which the movable body is in the occlusion position, preferably as long as the first and second component of the mixture are under pressure in the respective injection channel (and therefore they are in recirculation in the respective recirculation groove). In the embodiments which provide for channels totally internal to the movable body, keeping active the gas flow facilitates, for example, the cleaning of the mixing chamber. In the embodiments that provide for the first and second grooves, and/or channels having the respective inlet groove 21, keeping active the gas flow, in addition to facilitating cleaning, reduces the risk that the components can leak, due to pressure gradient, between the movable body 5 and the surface of the mixing chamber 3 towards one or both the first and second groove, and/or the inlet grooves, and occlude the passages used for the gas flow.