Spray head for spray-coating target object

Abstract

The present invention relates to a spray head for spray-coating a target object. The spray head comprises one or more spray head units. Each spray head unit comprises: a liquid supply unit for providing a liquid to be sprayed to a flow channel; the flow channel, which is in communication with a flow channel connection port of each capillary tube in a capillary tube group; and one or more rows of capillary tube groups, each capillary tube group in each row comprising a plurality of capillary tubes, which each comprises a main body portion, a flow channel connection port and a liquid outlet, wherein the flow channel connection port and the liquid outlet are respectively arranged at two ends of the main body portion, and the shape and size of the liquid outlet are configured such that said liquid is continuously output via the liquid outlet. The present invention has relatively low manufacturing costs, and can avoid the discharge of a fly liquid and improve the liquid spraying efficiency.

Description

A nozzle for target object spraying TECHNICAL FIELD

[0001] The present application relates to the field of inkjet technology, and in particular, to a nozzle for target object spraying. BACKGROUND

[0002] In the existing nozzle, for example, for coloring or spraying of a target object (e.g., a fabric), a liquid to be sprayed (e.g., ink) is atomized by, for example, ultrasonic atomization technology to be inkjet printed on the target object. The atomization of the liquid to be sprayed requires additional energy consumption, and the atomized droplets (e.g., ink droplets) that are not attached to the target object require a matching absorption device to reduce the impact on the environment. The existing nozzle based on ultrasonic atomization technology has technical advantages such as saving the liquid to be sprayed, and precisely controllable inkjet printing patterns. However, since it needs to be configured with a transducer for realizing ultrasonic atomization and an absorption device for absorbing excess atomized ink droplets, the manufacturing cost is relatively high, and in addition, the efficiency of atomized liquid coloring or spraying is poor.

[0003] In summary, the conventional nozzle has the disadvantages of high manufacturing cost, liquid emission (e.g., ink emission) problem, and poor liquid spraying (e.g., inkjet) efficiency. SUMMARY

[0004] The present application provides a nozzle for target object spraying, which can have a lower manufacturing cost and can avoid liquid emission and improve liquid spraying efficiency.

[0005] According to a first aspect of the present application, there is provided a nozzle for target object spraying, the nozzle comprising one or more nozzle units, each nozzle unit comprising: a liquid supply unit configured to supply a liquid to be sprayed to a flow channel; the flow channel being in communication with a flow channel connection port of each capillary tube in a capillary tube group; and one or more capillary tube groups, each capillary tube group comprising a plurality of capillary tubes, each capillary tube comprising a main body portion, a flow channel connection port, and a liquid outlet port, the flow channel connection port and the liquid outlet port being disposed at two end portions of the main body portion, respectively, the liquid outlet port being configured in shape and size such that the liquid to be sprayed is output from the liquid outlet port in a continuous output manner.

[0006] In some embodiments, the continuous output manner is a liquid column output manner.

[0007] In some embodiments, the liquid supply unit comprises a plurality of liquid inlets, and the flow channel is configured to adjust the flow rates of the plurality of liquid inlets such that the flow rates of the liquid to be sprayed at the positions of the plurality of capillary tubes are different from each other.

[0008] In some embodiments, the flow channel is configured as a longitudinal groove with an arc-shaped bottom surface on which an opening is provided in communication with the flow channel connection port of the capillary tube, and a height of the longitudinal groove is less than or equal to a predetermined height threshold.

[0009] In some embodiments, the two ends of the main body portion of the capillary tube are respectively a flow channel connection end and a liquid outlet end, an outer diameter of a first end of the liquid outlet end is greater than an outer diameter of a second end of the liquid outlet end, the first end of the liquid outlet end is connected to the main body portion, and the second end of the liquid outlet end is provided with the liquid outlet.

[0010] In some embodiments, an included angle between a side wall of the liquid outlet end of the capillary tube and a radial cross section of the capillary tube is greater than or equal to 10 degrees.

[0011] In some embodiments, the flow channel connection port is located at the first end of the flow channel connection end, and at least a portion of the liquid outlet end is configured as a tapered tube.

[0012] In some embodiments, a ratio of the inner diameter and the outer diameter of the second end of the liquid outlet end is configured such that a difference from a transition ratio threshold is less than a predetermined range, the transition ratio threshold corresponds to a transition liquid outlet flow rate, and the transition liquid outlet flow rate is a corresponding liquid outlet flow rate at a transition from a drop mode to a continuous spraying mode in which the liquid to be sprayed is output from the liquid outlet.

[0013] In some embodiments, the liquid supply unit further comprises a liquid distributor including a distributor inlet and a plurality of distributor outlets, a plurality of flow limiting valves, each flow limiting valve having an input end in communication with a corresponding distributor outlet of the plurality of distributor outlets, and a plurality of groups of proportional valves, each flow limiting valve having an output end in communication with a corresponding group of proportional valves of the plurality of groups of proportional valves.

[0014] In some embodiments, each group of proportional valves of the plurality of groups of proportional valves includes a plurality of proportional valves in communication with a plurality of liquid inlet ports of a corresponding spray head unit, respectively.

[0015] In some embodiments, each spray head unit further comprises a base plate having a plurality of mounting holes for mounting the group of capillary tubes and defining a spacing between the capillary tubes, a flow channel plate having one or more flow channels configured on a first surface of the flow channel plate, and a side wall forming a containing space of the group of capillary tubes with the base plate and a second surface of the flow channel plate.

[0016] In some embodiments, each spray head unit includes a plurality of sealing rings, each sealing ring of the plurality of sealing rings being disposed outside the flow channel connection end of a corresponding capillary tube for sealing the capillary tube.

[0017] In some embodiments, the sealing ring is disposed in a sealing ring clamping groove on a second side of the flow channel plate, and the flow channel is configured on a first surface of the flow channel plate.

[0018] In some embodiments, the bottom plate of the nozzle unit has a splicing structure for splicing between the bottom plates of adjacent nozzle units.

[0019] In some embodiments, the shape, size of the liquid outlet, and the distance between the liquid outlet and the target object are configured such that the liquid to be sprayed in the continuous liquid column section but not in the turbulent section of liquid column to droplet is provided to the target object.

[0020] The summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. The summary is not intended to identify key or essential features of the application, nor is it intended to limit the scope of the application. BRIEF DESCRIPTION OF DRAWINGS

[0021] FIG. 1 shows a longitudinal sectional view of a nozzle for target object spraying according to some embodiments of the present application.

[0022] FIG. 2 shows a side view of a containing space of a capillary tube group according to some embodiments of the present application.

[0023] FIG. 3 shows a top view of a flow channel plate according to some embodiments of the present application.

[0024] FIG. 4 shows a transverse sectional view of a nozzle unit according to some embodiments of the present application.

[0025] FIG. 5 shows a bottom view of a nozzle unit according to some embodiments of the present application.

[0026] FIG. 6 shows a partial enlarged view of a capillary tube according to some embodiments of the present application.

[0027] FIG. 7 shows a sectional view of a capillary tube according to some embodiments of the present application.

[0028] FIG. 8 shows a structural schematic view of a capillary tube according to some embodiments of the present application.

[0029] FIG. 9 shows a fluid property equivalent circuit schematic view of a flow channel and a capillary tube group according to some embodiments of the present application.

[0030] FIG. 10 shows a schematic view of continuous output and droplet output modes according to some embodiments of the present application.

[0031] FIG. 11 shows a schematic view of a liquid supply unit according to some embodiments of the present application.

[0032] FIG. 12 shows a schematic view of a nozzle unit group according to some embodiments of the present application.

[0033] In the various drawings, the same or corresponding reference numbers denote the same or corresponding parts. Detailed Implementation

[0034] Preferred embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While preferred embodiments of the invention are shown in the drawings, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that the invention will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0035] The term "comprising" and its variations as used herein signify open inclusion, i.e., "including but not limited to". Unless otherwise stated, the term "or" means "and / or". The term "based on" means "at least partially based on". The terms "one example embodiment" and "one embodiment" mean "at least one example embodiment". The term "another embodiment" means "at least one additional embodiment". The terms "first", "second", etc., may refer to different or the same objects.

[0036] As described above, the shortcomings of traditional nozzles are: high manufacturing costs and the problem of liquid splatter.

[0037] To at least partially address one or more of the aforementioned problems and other potential issues, exemplary embodiments of the present invention provide a spray head for spraying a target object. This spray head comprises one or more spray head units, each including: a liquid supply unit for supplying the liquid to be sprayed to a flow channel; a flow channel communicating with a flow channel connection port of each capillary in a capillary assembly; and one or more rows of capillary assemblies, each row comprising multiple capillary tubes, each capillary including a main body portion, a flow channel connection port, and a liquid outlet, the flow channel connection port and the liquid outlet being respectively disposed at two ends of the main body portion, the shape and size of the liquid outlet being configured such that the liquid to be sprayed is continuously output from the liquid outlet. By using capillary assemblies that continuously output the liquid to be sprayed from the liquid outlet instead of a spraying method based on ultrasonic atomization transducer technology, the present invention significantly reduces manufacturing costs, achieves higher spraying efficiency, and eliminates liquid splatter. Therefore, the present invention can achieve lower manufacturing costs and avoid liquid splatter emissions.

[0038] The following description, in conjunction with FIG1, exemplarily illustrates a spray nozzle 100 for spraying a target object. FIG1 shows a longitudinal sectional view of a spray nozzle 100 for spraying a target object according to some embodiments of the present invention.

[0039] The nozzle 100, for example, includes one or more nozzle units. FIG. 1 exemplarily shows a nozzle including one nozzle unit. As shown in FIG. 1, each nozzle unit includes a liquid supply unit, a flow channel 110, and one or more capillary tube groups 120 (two capillary tube groups are exemplarily shown in FIG. 1).

[0040] Regarding the liquid supply unit, it is used to provide the liquid to be sprayed to the flow channel. The liquid supply unit, for example, provides the liquid to be sprayed to the flow channel in a manner of constant flow source. In some embodiments, the liquid supply unit includes a plurality of liquid inlets 150. As shown in FIG. 1, each nozzle unit, for example, includes 3 liquid inlets 150 (a first liquid inlet 150-1 located at the left side of the flow channel, a second liquid inlet 150-2 located at the middle of the flow channel, and a third liquid inlet 150-3 located at the right side of the flow channel, respectively). In some embodiments, the liquid supply unit of each nozzle unit, for example, includes two liquid inlets 150, as shown in FIG. 11. It should be understood that the liquid supply unit can also include other number of liquid inlets.

[0041] Regarding the liquid to be sprayed, it is, for example, a functional liquid such as ink, dye, medicine, treatment liquid, etc. In some embodiments, the liquid to be sprayed is ink used for coloring target fabric.

[0042] Regarding the flow channel 110, it is used to provide the liquid to be sprayed from the liquid supply unit to the capillary tube group 120. The flow channel 110 is in communication with the flow channel connection port of each capillary tube in the capillary tube group 120. In FIG. 1, only the part of the flow channel 110 exposed by the liquid inlet 150 is shown.

[0043] Regarding the target object, it is, for example, target fabric, target substrate, etc.

[0044] Regarding the capillary tube group 120, it is used to output the liquid to be sprayed from the flow channel to the target object. Each nozzle unit includes one or more capillary tube groups 120. Each capillary tube group 120 includes a plurality of capillary tubes. Each capillary tube includes a main body portion, a flow channel connection port, and a liquid outlet port. The flow channel connection port and the liquid outlet port are respectively arranged at two end portions of the main body portion, and the shape and size of the liquid outlet port are configured to enable the liquid to be sprayed to be output from the liquid outlet port in a continuous output manner. Regarding the continuous output manner, it is, for example, a liquid column output manner, rather than a non-continuous manner such as liquid drop. It should be understood that, since the liquid to be sprayed is output from the liquid outlet port in a continuous output manner, the present application can significantly improve the liquid spraying efficiency.

[0045] With regard to the continuous output manner, it is, for example, a continuous liquid column output manner. FIG. 10 shows a schematic diagram of the continuous output and the drop output manner according to some embodiments of the present application. As shown in the left part of FIG. 10, the to-be-sprayed liquid is output from the liquid outlet of the capillary in the continuous output manner. As shown in the left part of FIG. 10, the to-be-sprayed liquid continuously output from the liquid outlet of the capillary includes, for example, a continuous liquid column segment 111, a liquid column to liquid drop turbulence segment 113, and a liquid drop 117. As shown in the right part of FIG. 10, the to-be-sprayed liquid is output from the liquid outlet of the capillary in the non-continuous drop output manner. The to-be-sprayed liquid output from the liquid outlet of the capillary in the drop output manner includes, for example, a liquid drop generation region 119 and a liquid drop 117. It should be understood that the shape and size of the liquid outlet of the present application are configured such that the to-be-sprayed liquid is output from the liquid outlet in the continuous output manner shown in the left part of FIG. 10. In some embodiments, the shape, size of the liquid outlet of the present application, and the distance between the liquid outlet and the target object are configured such that the to-be-sprayed liquid in the continuous liquid column segment 111 but not in the liquid column to liquid drop turbulence segment 113 is provided to the target object, thereby the spraying effect of the target object can be significantly improved.

[0046] It should be understood that when the to-be-sprayed liquid flows in the flow channel and the capillary, the flow channel and the capillary will have flow resistance. The size of the flow resistance is usually determined by the viscosity of the fluid, the length and radius of the flow channel. FIG. 9 shows a fluid property equivalent circuit schematic diagram of the flow channel and capillary group according to some embodiments of the present application. As shown in FIG. 9, there are N flow channel segments and N capillaries (N is, for example, a positive integer, and in some embodiments, N is an even number). In the flow channel, each flow channel segment between two openings has a certain flow resistance, denoted as R L1 indicating the flow resistance of the first flow channel segment (i.e., the flow channel before the first capillary); R LN indicating the flow resistance of the Nth flow channel segment. It should be understood that the flow resistance of the entire flow channel is similar to that of a plurality of flow channel segments “in series”. Each flow channel segment also has “inductive reactance” (inductive reactance indicates the property of the flow channel to resist changes in fluid flow as the fluid flow changes, denoted as L L1 indicating the inductive reactance of the first flow channel segment; L LN indicating the inductive reactance of the Nth flow channel segment). Each capillary in communication with the opening of the flow channel also has a flow resistance (denoted as R Z1 indicating the flow resistance of the first capillary; R ZN indicating the flow resistance of the Nth capillary), an inductive reactance (denoted as L Z1 indicating the inductive reactance of the first capillary; L ZN indicating the inductive reactance of the Nth capillary). In addition, each group of flow channel segments and capillaries also has a “capacitive reactance” (capacitive reactance indicates the storage amount of the fluid embodied by the gas-liquid, denoted as C LZ1indicates the inductance of the first flow channel section and the first capillary; L LZN indicates the inductance of the Nth flow channel section and the Nth capillary; L L indicates the constant current source connected to one end (e.g. the left end) of the flow channel; I M indicates the constant current source connected to the middle part of the flow channel (e.g. near the N / 2th capillary); I R indicates the constant current source connected to the other end (e.g. the right end) of the flow channel. As shown in FIG. 9, one end of the three constant current sources is connected and "grounded" (as indicated by the inverted triangle in FIG. 9). It should be understood that in the fluid property equivalent circuit, "voltage" corresponds to fluid pressure; "current" corresponds to the flow rate of the fluid. "Ground" corresponds to being connected to atmospheric pressure. It should be understood that the outlet of each capillary is connected to atmospheric pressure, so that one end of the capillary is "grounded".

[0047] The calculation methods of inductance, capacitance and flow resistance are exemplarily illustrated below in connection with equations (1) to (3), respectively.

[0048] In the above equation (1), L LN represents the inductance of the Nth flow channel section. p represents the density of the liquid to be sprayed. I LN represents the length of the Nth flow channel section. A R represents the cross-sectional area of the Nth flow channel section (taking a circular cross-sectional area as an example). It should be understood that the calculation method of the inductance of the capillary is similar.

[0049] In the above equation (2), C LZN represents the capacitance of the Nth flow channel section and the Nth capillary. V LZN represents the volume of the Nth flow channel section and the Nth capillary. B represents the bulk modulus of the Nth flow channel section and the Nth capillary.

[0050] In the above equation (3), R LN represents the flow resistance of the Nth flow channel section. p represents the viscosity of the liquid to be sprayed. I LN represents the length of the Nth flow channel section. r LN represents the radius of the cross-section (taking a circular cross-section as an example) of the Nth flow channel section. As can be seen from the above equation (3), the radius of the cross-section of the flow channel section has a greater impact on the flow resistance, and a small change in the radius will bring about a significant change in the flow resistance. It should be understood that the calculation method of the flow resistance of the capillary is similar. In addition, equations (1) to (3) take the flow channel and the capillary with a circular cross-section as an example. The cross-section of the flow channel and the capillary can also be of other shapes.

[0051] In some embodiments, the flow resistance of the flow channel is configured to adjust the flow rates of the plurality of liquid inlets such that the flow rates of the liquid to be sprayed at the locations of the plurality of capillaries are different from each other. For example, I L I indicates a constant flow source in communication with one end (e.g., the left end) of the flow channel, for example, in communication with the first liquid inlet 150-1 located at the left side of the flow channel. I in FIG. 9 M I indicates a constant flow source in communication with the middle portion of the flow channel, for example, in communication with the second liquid inlet 150-2 located at the middle of the flow channel. I in FIG. 9 R I indicates a constant flow source in communication with the other end (e.g., the right end) of the flow channel, for example, in communication with the third liquid inlet 150-3 located at the right side of the flow channel. In some embodiments, if the flow resistance of the flow channel is relatively large, in the steady state, the linear variation of the flow rates at the capillaries can be achieved by controlling the liquid inlets at the left side of the flow channel, the middle of the flow channel, and the right side of the flow channel, respectively. For example, the flow rates at the capillaries gradually change from left to right. For example, the liquid inlet at the left side of the flow channel has a liquid flow rate of 100% of a predetermined value; the liquid inlet at the middle of the flow channel has a liquid flow rate of -100% of the predetermined value; and the liquid inlet at the right side of the flow channel has a liquid flow rate of 100% of the predetermined value. At this time, the phenomenon that the liquid flow rates at the two ends of the flow channel are high and the liquid flow rate at the middle of the flow channel is low is achieved, so that the flow rates at different capillaries are different. For another example, the liquid inlet at the left side of the flow channel has a liquid flow rate of 100% of a predetermined value; the liquid inlet at the middle of the flow channel has a liquid flow rate of -50% of the predetermined value; and the liquid inlet at the right side of the flow channel has a liquid flow rate of 50% of the predetermined value. It should be understood that, for example, in the process of spraying a fabric, the fabric may, before entering the spraying area, exhibit a state of uneven density due to a pretreatment process. If the amount of dyeing liquid (i.e., the liquid to be sprayed) is the same when spraying, the final color of the fabric will appear uneven. The present application can achieve uniform coloring or spraying of the entire fabric by controlling the liquid flow rates of the plurality of liquid inlets at different positions of the flow channel to achieve different (e.g., linearly varying) flow rates of the liquid to be sprayed at different capillaries, thereby outputting different flow rates of the liquid to be sprayed at different capillaries in view of the state of uneven density of the fabric over the entire width.

[0052] The main portion of the capillary (indicated by 126 in FIG. 4) is, for example, an elongated circular tube. The two end portions at the two ends of the main portion are a flow channel connection end (indicated by 124 in FIG. 4) and a liquid outlet end 122, respectively.

[0053] The structure of the liquid outlet end 122 of the capillary tube is described in detail below in connection with FIGS. 6-8. FIG. 6 shows a partial enlarged view of a capillary tube according to some embodiments of the present application. FIG. 7 shows a cross-sectional view of a portion of a capillary tube according to some embodiments of the present application. FIG. 8 shows a structural schematic view of a capillary tube according to some embodiments of the present application. As shown in FIG. 6, one end of the main body portion 126 of the capillary tube is the liquid outlet end 122. The first end 127 of the liquid outlet end 122 is connected to the main body portion 126, and the second end 128 of the liquid outlet end 122 is the liquid outlet.

[0054] In some embodiments, the outer diameter of the first end 127 of the liquid outlet end 122 (e.g., indicated by "DN" in FIGS. 7 and 8) is greater than the outer diameter of the second end 128 of the liquid outlet end 122 (e.g., indicated by "D" in FIGS. 6-8). In this way, the liquid outlet flow rate of the liquid outlet can be controlled. It should be understood that the outer diameter of the first end 127 of the liquid outlet end 122, i.e., the outer diameter of the capillary tube. In some embodiments, the outer diameter of the capillary tube is greater than or equal to 0.1 mm.

[0055] Regarding the inner diameter of the liquid outlet end 122, in some embodiments, the inner diameter (dn) of the first end 127 of the liquid outlet end 122 is equal to the inner diameter (d) of the second end 128 of the liquid outlet end 122, as shown in FIG. 7. In some embodiments, the inner diameter (dn) of the first end 127 of the liquid outlet end 122 is greater than the inner diameter (d) of the second end 128 of the liquid outlet end 122, as shown in FIG. 8. In other embodiments, the inner diameter of the first end 127 of the liquid outlet end 122 is equal to the inner diameter of the second end 128 of the liquid outlet end 122, and the outer diameter of the first end 128 of the liquid outlet end 122 is equal to the outer diameter of the second end 128 of the liquid outlet end 122. In some embodiments, the inner diameter (d) of the second end 128 of the liquid outlet end 122 is equal to the outer diameter (D) of the second end 128 of the liquid outlet end 122. In some embodiments, the inner diameter (d) of the second end 128 of the liquid outlet end 122 is greater than or equal to 0.02 mm.

[0056] In some embodiments, the outer wall profile of the liquid outlet end 122 is configured, for example, as an arc shape, a stepped shape, or a segmented shape. In some embodiments, at least a portion of the liquid outlet end 122 is configured, for example, as a tapered tube. As shown in FIG. 7, the entire liquid outlet end 122 is configured, for example, as a tapered tube, it should be understood that the outer diameter of the tapered tube gradually decreases, and the inner diameter of the tapered tube can remain unchanged or gradually decrease. For example, as shown in FIG. 7, in the direction extending from the first end 127 to the second end 128 (d), the outer diameter of the liquid outlet end 122 gradually decreases from the outer diameter (DN) at the first end 127 to the outer diameter (D) at the second end 128, while the inner diameter of the liquid outlet end 122 remains unchanged, i.e., equal to the inner diameter of the second end 128. It should be understood that by configuring the liquid outlet end as a tapered tube with an unchanged inner diameter, the liquid outlet flow rate of the liquid outlet can be controlled and the processing is facilitated.

[0057] The cross-sectional view in the upper right corner of FIG. 8 is a magnified view of the area enclosed by the circle indicated by marker 121. As shown in FIG. 8, a portion of liquid outlet end 122 is configured as a tapered tube, for example, liquid outlet end 122 is configured as a combination of a tapered tube and a cylindrical tube. The axial height n of the tapered tube is less than or equal to the axial height of liquid outlet end 122. The difference between the outer diameter (DN) at first end 127 and the inner diameter (dn) at first end 127 can or can not be equal to the difference between the outer diameter (D) at second end 128 and the inner diameter (d) at second end 128. In the direction in which first end 127 extends to second end 128 (d), the outer diameter of liquid outlet end 122 gradually decreases from the outer diameter of the end of the cylindrical tube to the outer diameter (D) at second end 128; at the same time, the inner diameter of liquid outlet end 122 gradually decreases from the inner diameter (dn) at first end 127 to the inner diameter (d) at second end 128. It should be understood that by configuring at least a portion of the liquid outlet end as a tapered tube with both the inner and outer diameters decreasing, it is easier to more effectively control the liquid flow rate from the liquid outlet. With respect to the sidewall of the liquid outlet end of the capillary tube, in some embodiments, as shown in FIG. 7, the sidewall 810 of the liquid outlet end of the capillary tube is at an angle θ with respect to the radial cross-section 812 of the capillary tube that is greater than or equal to 10 degrees. In some embodiments, the angle θ is any value greater than or equal to 10 degrees and less than 90 degrees. In some embodiments, the angle θ is any value greater than or equal to 80 degrees and less than 90 degrees. By setting the angle θ within the above-mentioned angle range, it is possible to avoid wetting of the liquid output from the liquid outlet to the side of the liquid outlet end, so as to facilitate the formation of a continuous liquid column. It should be understood that if the liquid output from the liquid outlet wets the side of the liquid outlet end, it is easy to form an asymmetric wetting condition, which in turn negatively affects the continuous liquid column output from the liquid outlet.

[0058] As shown in FIG. 6, arrow 123 indicates, for example, the inner diameter of second end 128 of liquid outlet end 122, which is represented, for example, by the letter “d”. Arrow 125 indicates, for example, the outer diameter of second end 128 of liquid outlet end 122, which is represented, for example, by the letter “D”.

[0059] The relationship between the inner diameter d and the outer diameter D of the liquid outlet and the critical Weber number is explained below in connection with equations (4) to (6). B0= [pgD 2 / (2σ] 1 / 2 (5)

[0060] In the above equation (4), represents the critical Weber number. B0and represent the Bond numbers based on the inner diameter and the outer diameter of the liquid outlet, respectively. K represents a constant. B0and The ratio of the Weber number to the ratio of the inner diameter to the outer diameter. In the above equations (5) and (6), p represents the density of the liquid to be sprayed. s represents the surface tension of the liquid to be sprayed. g represents the acceleration of gravity. v0represents the flow rate of the liquid to be sprayed. D represents the inner diameter (diameter) of the capillary of the outlet. It should be understood that the Weber number is a dimensionless number used in fluid mechanics that characterizes the ratio of the deformation inertial forces to the stabilizing cohesive forces of a liquid (e.g., the liquid to be sprayed) flowing through a fluid medium (e.g., the capillary). The cohesive forces are related to the surface or interfacial tension that resists an increase in surface area, resulting in deformation. Thus, the droplets of the liquid to be sprayed will come together due to the surface or interfacial tension. Critical Weber number The Weber number of the liquid to be sprayed having the density p and the surface tension s at the flow rate v0through the outlet having the inner diameter D, at which the liquid to be sprayed is output from the outlet in the droplet mode to the continuous spray mode (or "continuous output mode," e.g., a liquid column). It should be understood that the critical Weber number The transition flow rate at which the mode of the liquid to be sprayed output from the outlet changes from the droplet mode to the continuous spray mode.

[0061] With respect to the transition flow rate, it is, for example, the corresponding flow rate at which the mode of the liquid to be sprayed output from the outlet changes from the droplet mode (or "droplet output mode") shown in the right portion of FIG. 10 to the continuous spray mode (or "continuous output mode," or "liquid column mode") shown in the left portion of FIG. 10.

[0062] It has been found that when the inner diameter of the capillary (e.g., the inner diameter of the outlet end is equal to the inner diameter of the capillary) is sufficiently small, the interface of the liquid to be sprayed can be stabilized to Rayleigh-Taylor instability (RT instability), in which the inertia of the liquid to be sprayed, the capillary action of the capillary, and the gravitational effect of the liquid to be sprayed dominate over the viscosity of the liquid to be sprayed. When the inner diameter d of the outlet is constant, the closer the outer diameter D is to the inner diameter d (i.e., the smaller the outer diameter D), the smaller the transition flow rate at which the liquid to be sprayed output from the outlet changes from the droplet mode to the continuous spray mode. In some embodiments, the ratio of the inner diameter to the outer diameter of the second end of the outlet end is configured to be within a predetermined range of a transition ratio threshold corresponding to a transition outlet flow rate at which the mode of the liquid to be sprayed output from the outlet changes from the droplet mode to the continuous spray mode.

[0063] As shown in FIGS. 1 and 2, in some embodiments, each of the spray head units further includes a base plate 130, a side wall 132, a flow channel plate 134, and a plurality of sealing rings 140.

[0064] As to the bottom plate 130, it has a plurality of mounting holes for mounting the capillary tube group 120, and defines the spacing between the capillary tubes.

[0065] As to the flow channel plate 134, its first surface (e.g., the upper surface of the flow channel plate 134 in FIG. 1) is configured with one or more flow channels 110. In some embodiments, the second surface of the flow channel plate 134 (e.g., the lower surface of the flow channel plate 134 in FIG. 1) is provided with gasket snap groove for snap sealing gasket 140.

[0066] As to the side wall 132, it forms the containing space of the capillary tube group 120 with the bottom plate 130 and the second surface of the flow channel plate 134. In some embodiments, the side wall 132 includes, for example, at least a first side wall 132-1 and a second side wall 132-2 (as shown in FIG. 2).

[0067] As to the sealing gasket 140, it is used to seal the capillary tubes. In some embodiments, the number of sealing gaskets is equal to the number of capillary tubes. As shown in FIG. 1, each sealing gasket is disposed outside the flow channel connecting end of the corresponding capillary tube for sealing the capillary tube. The partial enlarged view of the portion within the virtual line indicated by marker 102 in the upper left corner of FIG. 1 shows that each sealing gasket 140 is sleeved outside the flow channel connecting end of the corresponding capillary tube. And the sealing gasket is disposed in the gasket snap groove on the second side of the flow channel plate 134.

[0068] In some embodiments, each nozzle unit further includes, for example, a top plate 138, a sealing plate 136 and a mounting plate 142.

[0069] As to the top plate 138, it is configured, for example, to be located on the upper surface of the nozzle unit. In some embodiments, the top plate 138 is used to mount one or more liquid inlets 150.

[0070] As to the sealing plate 136, it is disposed between the top plate 138 and the flow channel plate 134 for sealing the communication space between the flow channels and the liquid inlets 150. In some embodiments, both the sealing plate 136 and the top plate 138 are provided with through holes (e.g., the top plate through hole 139 and the sealing plate through hole 137 shown in FIG. 2) that pass through the liquid inlets 150, so as to guide the liquid to be sprayed from the liquid inlets 150 to the flow channels 110.

[0071] As to the mounting plate 142, it is disposed, for example, between the flow channel plate 134 and the side wall 132 for realizing the relative fixation between the flow channel plate 134 and the side wall 132.

[0072] The following illustrates the schematic diagram of the containing space of the capillary tube group in conjunction with FIG. 2. FIG. 2 shows the side view of the containing space of the capillary tube group according to some embodiments of the present application.

[0073] Regarding the capillary set accommodating space 135, in some embodiments, it is defined by, for example, the sidewall 132 (the sidewall 132 specifically includes, for example, the first sidewall 132-1 and the second sidewall 132-2), the upper surface of the bottom plate 130, and the second surface (i.e., the lower surface) of the flow channel plate 134, as shown in FIG. 2. It should be understood that each nozzle unit accommodates, for example, one capillary set accommodating space 135. Each capillary set accommodating space 135 accommodates, for example, one or more rows of capillary sets. As shown in FIG. 2, the capillary set accommodating space 135 accommodates two rows of capillary sets.

[0074] The schematic diagram of the flow channel plate 134 is exemplarily described below in conjunction with FIG. 3. FIG. 3 shows a top view of a flow channel plate according to some embodiments of the present application.

[0075] As shown in FIG. 3, the flow channel plate 134 has a first surface (i.e., the upper surface of the flow channel plate 134) and a second surface (i.e., the lower surface of the flow channel plate 134).

[0076] The first surface of the flow channel plate 134 is configured with, for example, a plurality of flow channels 110. The first surface of the flow channel plate 134 includes 2 flow channels, as shown schematically in FIG. 3. It should be understood that the number of flow channels 110 configured on the flow channel plate 134 of each nozzle unit is equal to the number of rows of capillary sets, and each flow channel 110 is used to provide the liquid to be sprayed to a corresponding row of capillary tubes 120. Each flow channel 110 includes, for example, a plurality of openings through which the flow channel communicates with the flow channel connection port of a corresponding capillary tube in the capillary set. In some embodiments, the flow channel plate 134 is further provided with a plurality of mounting holes 114 for achieving the relative fixation between the flow channel plate 134 and the sealing plate 136, the mounting plate 142, and / or the sidewall 132.

[0077] Regarding the flow channel 110, in some embodiments, the flow resistance of the flow channel is configured to adjust the flow rate of the plurality of liquid inlets so that the flow rates of the liquid to be sprayed at the positions of the plurality of capillary tubes are different from each other. As shown in FIG. 3, the label 112-M indicates the Mth opening, which corresponds, for example, to the position of the Mth capillary tube. The label 112-N indicates the Nth opening. The Nth opening corresponds, for example, to the position of the Nth capillary tube. It should be understood that the flow resistance of the flow channel 110 is configured to adjust the flow rate of the plurality of liquid inlets so that the flow rates of the liquid to be sprayed at the positions of the plurality of capillary tubes at the position of the Mth capillary tube and at the position of the Nth capillary tube are different from each other.

[0078] In some embodiments, the flow channel 110 is configured, for example, as a longitudinal groove, the bottom surface of which is an arc surface on which the opening hole communicating with the flow channel connection port of the capillary tube is arranged. It should be understood that by arranging the bottom surface of the flow channel 110 as an arc surface, the flow channel of the present application can reduce the residue of the liquid to be sprayed in the flow channel.

[0079] As to the longitudinal groove, it is, for example, an elongated shallow groove extending along the X direction in FIG. 3. In some embodiments, the cross section of the longitudinal groove is semicircular. In some embodiments, the height of the longitudinal groove is less than or equal to a predetermined height threshold. As to the predetermined height threshold, it is, for example, but not limited to, 1 millimeter. For example, in some embodiments, the height of the longitudinal groove is configured to be 0.5 millimeter. By making the height of the longitudinal groove very low, i.e., making the longitudinal groove an elongated shallow groove, it is facilitated to control the flow resistance of the flow channel. In some embodiments, the width of the longitudinal groove is, for example, 1 millimeter.

[0080] It should be understood that, under low flow resistance, slight change of the flow resistance in the pipeline will significantly affect the stability of the flow rate of the liquid to be sprayed. By making the flow resistance of the flow channel larger (e.g., making the flow resistance of the flow channel exceed a predetermined flow resistance threshold), the stability of the flow rate of the liquid to be sprayed by the spray head can be improved.

[0081] In some embodiments, the cross-sectional area of the flow channel is, for example, configured to be less than a predetermined cross-sectional area threshold. In some embodiments, the cross-sectional area of the flow channel is, for example, but not limited to, 0.5 square millimeters. In some embodiments, the cross-sectional area of the flow channel is determined based on the sensitivity requirement of the flow control of the liquid to be sprayed by the spray head. It should be understood that the flow resistance in the microfluid is mainly caused by the pressure drop and energy loss caused by the friction between the liquid and the channel wall. Experimental data shows that, when the liquid to be sprayed with viscosity is in a laminar flow state, the closer the liquid to be sprayed is to the wall of the flow channel, the greater the flow resistance is, and the smaller the flow rate is; under the same pressure, the smaller the inner diameter size of the flow channel is, the greater the flow resistance is, and the lower the flow rate is. Therefore, by configuring the flow channel as an elongated shallow groove and making the cross-sectional size thereof small enough, the flow resistance in the flow channel is increased, the flow rate is reduced, and the sensitivity of the flow control of the liquid to be sprayed by the spray head is improved.

[0082] FIG. 4 shows a transverse sectional view of the spray head unit according to some embodiments of the present application.

[0083] As shown in FIGS. 3 and 4, the bottom plate 130 is provided with mounting holes. The mounting plate 142 is provided with mounting holes. The side wall 132 is also provided with mounting holes. By sequentially passing through the mounting holes on the bottom plate 130, the side wall 132 and the mounting plate 142 through the first mounting device 144, the fixation between the bottom plate 130, the side wall 132 and the mounting plate 142 is achieved.

[0084] As shown in FIG. 4, by coupling the mounting holes on the top plate 138, the sealing plate 136, the flow channel plate 134 and the mounting plate 142 through the second mounting device 146, the relative fixation between the top plate 138, the sealing plate 136, the flow channel plate 134 and the mounting plate 142 is achieved.

[0085] In some embodiments, the first mounting device 144 and the second mounting device 146 are configured in a manner of screws, for example. In some embodiments, coupling and decoupling can be achieved between the first mounting device 144 and the second mounting device 146.

[0086] It should be appreciated that, by means of the above mounting manner, the present application facilitates local maintenance and installation. For example, by decoupling between the first mounting device 144 and the mounting holes on the bottom plate 130, the side wall 132 and the mounting plate 142, the bottom plate 130 and the side wall 132 can be conveniently disassembled, so that the installation and maintenance of the capillary tubes can be conveniently performed without affecting the relative fixation between the top plate 138, the sealing plate 136, the flow channel plate 134 and the mounting plate 142. Similarly, by decoupling between the second mounting device 146 and the mounting holes on the top plate 138, the sealing plate 136, the flow channel plate 134 and the mounting plate 142, the top plate 138, the sealing plate 136 and the flow channel plate 134 can be conveniently disassembled, so that the installation and maintenance of the flow channel or the liquid inlet can be conveniently performed without affecting the relative fixation between the bottom plate 130, the side wall 132 and the capillary tube group.

[0087] The dashed box in the upper right corner of FIG. 4 is an enlarged view of the partial structure within the dashed box indicated by the marker 148. The marker 112 indicates an opening of the flow channel. The opening 112 is located on the bottom surface of the flow channel of the first surface 115 of the flow channel plate 134, for example. The opening 112 is in communication with the flow channel connecting end of the capillary tube, and is used to provide the liquid to be sprayed in the flow channel to the capillary tube via the opening 112. The liquid to be sprayed provided to the capillary tube successively flows through the flow channel connecting end, the main body portion 126 of the capillary tube, and finally is output from the liquid outlet of the second end (i.e., the terminal end) of the liquid outlet end 122.

[0088] FIG. 4 also shows that the second surface 118 of the flow channel plate 134 is configured with a sealing ring clamping groove 116. The sealing ring clamping groove 116 is used to clamp the sealing ring 140, so that the sealing ring 140 is fixed outside the flow channel connecting end of the capillary tube, so as to seal the flow channel connecting end of the capillary tube. FIG. 5 shows a bottom view of the nozzle unit according to some embodiments of the present application.

[0089] In some embodiments, the ratio of the inner diameter and the outer diameter of the second end of the liquid outlet end is configured to have a difference from a transition ratio threshold value less than a predetermined range, the transition ratio threshold value corresponding to a transition liquid outlet flow rate, the transition liquid outlet flow rate being a corresponding liquid outlet flow rate at which the liquid to be sprayed is output from the liquid outlet in a manner of transition from a dripping manner to a continuous spraying manner.

[0090] The structure of the liquid supply unit of the plurality of nozzle units will be described in detail below in conjunction with FIG. 11. FIG. 11 shows a schematic diagram of a liquid supply unit of a plurality of nozzle units according to some embodiments of the present application. As shown in FIG. 11, the liquid supply unit 170 is configured to supply the liquid to be sprayed to a group of nozzle units 172. The group of nozzle units 172 is, for example, spliced by a plurality of nozzle units. The liquid supply unit 170 includes a liquid distributor 180, a plurality of flow restrictors 190, a plurality of groups of proportional valves 192, and connecting pipelines. The liquid distributor is configured to distribute the liquid to be sprayed supplied through a distributor inlet 182 to each of the flow restrictors 192 through a plurality of distributor outlets 184, respectively. The liquid distributor 180 includes the distributor inlet 182 and the plurality of distributor outlets 184. The distributor inlet 182 is, for example, in communication with a constant flow source for receiving the liquid to be sprayed at a constant flow. The plurality of distributor outlets 184 are in communication with the plurality of flow restrictors 190, respectively. The flow restrictors 190 are configured to adjust the flow rate of the liquid to be sprayed supplied to the corresponding group of proportional valves 192 according to a control instruction, which is, for example, generated based on the density distribution data of the target object (e.g., fabric), which is, for example, provided by the supplier of the target object or generated based on the detection data of the target object. Each of the flow restrictors 190 is in communication with a group of proportional valves 192, respectively. Each group of proportional valves 192 includes, for example, a plurality of proportional valves. As shown in FIG. 11, each of the flow restrictors 190 is in communication with a group of proportional valves 192 including a first proportional valve 192-1 and a second proportional valve 192-2, respectively. Different proportional valves in the same group of proportional valves are in communication with different liquid inlets 150 in the same nozzle unit, respectively. For example, the first proportional valve 192-1 is in communication with the first liquid inlet 150-1 for adjusting the flow rate of the liquid supplied to the first liquid inlet 150-1. The second proportional valve 192-2 is in communication with the second liquid inlet 150-2 for adjusting the flow rate of the liquid supplied to the second liquid inlet 150-2. By using the above scheme, the present application not only can conveniently supply the liquid (e.g., ink) to the group of nozzle units, but also can individually control the flow rate of the capillary tubes in different nozzle units, thereby overcoming the problem of uneven coloring or spraying caused by the uneven density in the width direction of the fabric.

[0091] The splicing manner of the plurality of nozzle units will be described in detail below in conjunction with FIG. 12. FIG. 12 shows a schematic diagram of a group of nozzle units according to some embodiments of the present application. As shown in FIG. 12, the group of nozzle units 170 includes, for example, a plurality of nozzle units (e.g., the group of nozzle units 170 includes a first nozzle unit 170-1, a second nozzle unit 170-2, and a third nozzle unit 170-3). The bottom plate 130 of each nozzle unit has, for example, a splicable structure 129 for splicing with the bottom plate of the adjacent nozzle unit. In some embodiments, the splicable structure 129 is, for example, one or more sets of mortise and tenon mechanisms. In other embodiments, the splicable structure 129 is, for example, one or more sets of locking mechanisms.

[0092] By adopting the above manner, the printing equipment of various widths can be conveniently constructed, and coloring or spraying requirements of different width fabrics can be met. It should be understood that the side wall and the bottom plate of any one of the nozzle units (for example, the second nozzle unit 170-2) in FIG. 12 can be independently installed and disassembled, so that the present application can conveniently perform independent maintenance and repair (for example, damage of a liquid outlet of the capillary tube or blockage of the capillary tube) on the capillary tube of the nozzle unit without disassembling the entire nozzle unit.

[0093] The above has described the embodiments of the present application, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes are obvious to those skilled in the art without departing from the scope and spirit of the described embodiments.

[0094] The selection of the terms used herein is intended to best explain the principles of the embodiments, practical application, or technical improvement in the art, or to enable other ordinary skilled persons in the art to understand the embodiments disclosed herein.

[0095] The above specific embodiments do not constitute a limitation on the scope of protection of the present application. Those skilled in the art should understand that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors.

Claims

1. A spray head for spray painting of a target object, characterized in that, The inkjet head unit comprises: a liquid supply unit configured to supply the liquid to be sprayed to the flow channel; the flow channel is in communication with the flow channel connection port of each capillary tube in the capillary tube group; and one or more capillary tube groups, each capillary tube group comprising a plurality of capillary tubes, each capillary tube comprising a main body portion, a flow channel connection port, and a liquid outlet port, the flow channel connection port and the liquid outlet port being respectively arranged at two end portions of the main body portion, the liquid outlet port being configured in shape and size such that the liquid to be sprayed is output from the liquid outlet port in a continuous output manner.

2. The showerhead of claim 1, wherein The continuous output manner is a liquid column output manner.

3. The showerhead of claim 1, wherein The liquid supply unit comprises a plurality of liquid inlets, and the flow channel is configured to adjust the flow rates of the plurality of liquid inlets so that the flow rates of the liquid to be sprayed at positions where the plurality of capillary tubes are located are different from each other.

4. The showerhead of claim 1, wherein The flow channel is configured as a longitudinal groove, a bottom surface of the longitudinal groove is an arc surface, and an opening is arranged on the arc surface and in communication with the flow channel connection port of the capillary tube, and a height of the longitudinal groove is less than or equal to a predetermined height threshold.

5. The showerhead of claim 1, wherein The two end portions of the main body portion of the capillary tube are respectively a flow channel connection end and a liquid outlet end, an outer diameter of a first end of the liquid outlet end is greater than an outer diameter of a second end of the liquid outlet end, the first end of the liquid outlet end is connected to the main body portion, and the second end of the liquid outlet end is provided with the liquid outlet port.

6. The showerhead of claim 5, wherein, An included angle between a side wall of the liquid outlet end of the capillary tube and a radial cross section of the capillary tube is greater than or equal to 10 degrees.

7. The showerhead of claim 5, wherein, The flow channel connection port is located at the first end of the flow channel connection end, and at least a portion of the liquid outlet end is configured as a tapered tube.

8. The showerhead of any of claims 5-7, wherein, A ratio of an inner diameter to an outer diameter of the second end of the liquid outlet end is configured such that a difference from a transition ratio threshold is less than a predetermined range, the transition ratio threshold corresponds to a transition liquid outlet flow rate, and the transition liquid outlet flow rate is a corresponding liquid outlet flow rate when a transition from a drop output manner to a continuous spraying manner occurs in the manner in which the liquid to be sprayed is output from the liquid outlet port.

9. The showerhead of claim 1, wherein The liquid supply unit further comprises: a liquid distributor comprising a distributor inlet and a plurality of distributor outlets; a plurality of flow limiting valves, an input end of each flow limiting valve being in communication with a corresponding distributor outlet of the plurality of distributor outlets; and a plurality of groups of proportional valves, an output end of each flow limiting valve being in communication with a corresponding group of proportional valves of the plurality of groups of proportional valves.

10. The showerhead of claim 9, wherein, A plurality of proportional valves included in each group of proportional valves are respectively in communication with a plurality of liquid inlets in a corresponding inkjet head unit.

11. The showerhead of claim 1, wherein Each inkjet head unit further comprises: a bottom plate having a plurality of mounting holes for mounting the capillary tube group and defining a spacing between the capillary tubes; a flow channel plate, one or more flow channels being arranged on a first surface of the flow channel plate; and a side wall, the side wall forming, together with the bottom plate and a second surface of the flow channel plate, a containing space for the capillary tube group.

12. The showerhead of claim 5, wherein, Each inkjet head unit comprises: a plurality of sealing rings, each sealing ring of the plurality of sealing rings being arranged outside the flow channel connection end of a corresponding capillary tube for sealing the capillary tube.

13. The showerhead of claim 12, wherein, The sealing ring is arranged in a sealing ring buckle slot on a second side of the flow channel plate, and the flow channel is arranged on a first surface of the flow channel plate.

14. The showerhead of claim 11, wherein, The bottom plate of the inkjet head unit has a splicing structure for splicing between the bottom plates of adjacent inkjet head units.

15. The showerhead of claim 11, wherein, The shape, size, and distance between the liquid outlet and the target object of the liquid outlet are configured such that the liquid to be sprayed in the continuous liquid column section, not the disturbed section in which the liquid column changes into liquid drops, is provided onto the target object. The shape, size, and distance between the liquid outlet and the target object of the liquid outlet are configured such that the liquid to be sprayed in the continuous liquid column section, not the disturbed section in which the liquid column changes into liquid drops, is provided onto the target object. The shape, size, and distance between the liquid

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