JP2023144924A - Spray nozzle and spray method - Google Patents

Abstract

To provide a spray nozzle capable of efficiently spraying a spray material while uniformly controlling the concentration distribution of the spray material to be discharged, and a spray method.SOLUTION: A spray nozzle for spraying slurry spray material comprises a cylinder with a flow path formed inside, and a plurality of independent protrusions that protrude from the inner peripheral surface of the cylinder toward the inside of the cylinder. The plurality of protrusions are arranged spirally on the inner peripheral surface of the cylinder.SELECTED DRAWING: Figure 1

Description

The present invention relates to a spraying method for spraying a spraying material such as mortar onto a construction target such as a concrete structure, and a spraying nozzle used in the spraying method.

BACKGROUND ART When repairing or reinforcing concrete structures, etc., a spraying method in which a spraying material such as mortar is sprayed onto the construction surface is sometimes carried out. Specifically, in the mortar spraying method, mortar prepared with cement, aggregate, water, etc. is pumped, and the mortar is discharged from a spray nozzle installed at the end of a hose, etc., to form a concrete structure. Mortar is sprayed onto the construction surface of an object, etc. (Patent Document 1).

Japanese Patent Application Publication No. 5-98648

In such a mortar spraying method, it has been thought that in order to thicken the mortar on the construction surface, it is necessary to increase the discharge speed of the mortar. However, with conventional spray nozzles, simply increasing the mortar discharge speed causes the amount of mortar discharged from around the center of the nozzle to be larger than the amount discharged around it, causing the mortar concentration distribution to shift around the center of the nozzle. This resulted in a lopsided conical shape, resulting in poor flatness of the mortar sprayed onto the construction surface. Further, if the material discharged from the nozzle is biased toward the center, the material itself discharged from the center will blow away the material attached to the construction surface, resulting in a problem that it is not possible to thicken the material efficiently.

An object of the present invention is to provide a spray nozzle and a spraying method that can efficiently spray the spray material while controlling the concentration distribution of the spray material to be discharged as uniformly as possible.

One aspect of the present invention is
A spray nozzle for spraying slurry-like spray material,
A cylindrical body with a flow path formed inside;
a plurality of independent protrusions that protrude from the inner circumferential surface of the cylindrical body toward the inside of the cylindrical body;
The spray nozzle is characterized in that the plurality of protrusions are arranged spirally on the inner circumferential surface of the cylindrical body.

According to the spray nozzle having such a configuration, the flow direction of the sprayed material is changed by colliding with the plurality of independent protrusions when passing through the cylindrical body, and the velocity between the center and the surrounding area is changed. The difference is reduced, and the spray material discharged from the spray nozzle has a uniform concentration. This makes it possible to spray the spraying material to a uniform thickness on the construction surface.

The plurality of protrusions may be arranged at equal intervals on the inner peripheral surface of the cylindrical body when viewed from the center line direction of the cylindrical body, and preferably, the plurality of protrusions are arranged at equal intervals on the inner peripheral surface of the cylindrical body when viewed from the center line direction of the cylindrical body. It includes three protrusions arranged at 120° intervals on the circumference.

With this configuration, it becomes possible to spray the spraying material with a more uniform thickness onto the construction surface.

A ratio (r2/D) of the height r2 of the protrusion to the inner diameter D of the cylindrical body may be 0.3 or more and 0.55 or less.

With this configuration, it becomes possible to spray the spraying material with a more uniform thickness onto the construction surface.

Each of the protruding parts preferably has an inclined part whose cross-sectional area increases toward the downstream side of the flow path.

With this configuration, when the sprayed material flowing in the axial direction of the cylinder collides with the plurality of protrusions, the flow direction of the sprayed material is changed with less resistance, and the concentration is made even more effective. Become something.

The inclined portion preferably has a conical shape, and the center line of the conical shape is arranged substantially parallel to the center of the cylinder.

With this configuration, when the sprayed material flowing in the axial direction of the cylindrical body collides with the plurality of protrusions, the flow direction is changed with less resistance, making concentration uniformity even more effective. Become.

Moreover, a spraying method as one aspect of the present invention is one in which a spraying material is sprayed using any of the above-mentioned spray nozzles.

According to the spraying method having such a configuration, it becomes possible to uniformly spray the spraying material onto the construction surface.

As described above, the present invention provides a spray nozzle and a spray construction method that can efficiently spray a spray material to a construction surface with a uniform thickness.

FIG. 1 is a perspective view, partially in section, showing a spray nozzle of one embodiment. FIG. 2 is an axial cross-sectional view showing a spray nozzle of one embodiment. FIG. 3 is a side view of the spray nozzle of FIG. 2 viewed from the upstream side in the axial direction. FIG. 4 is an axial cross-sectional view showing a spray nozzle of another embodiment. FIG. 5 is an axial cross-sectional view showing a spray nozzle of another embodiment. FIG. 6 is an axial cross-sectional view showing an embodiment of the spray nozzle used in the simulation. FIG. 7 shows simulation results using the spray nozzle of Example 5, and is a graph showing the distribution state of the spray material at a predetermined distance from the nozzle outlet. FIG. 8 shows simulation results using the spray nozzle of Example 10, and is a graph showing the distribution state of the spray material at a predetermined distance from the nozzle outlet. FIG. 9 shows simulation results using the spray nozzle of Example 11, and is a graph showing the distribution state of the spray material at a predetermined distance from the nozzle outlet. FIG. 10 shows simulation results using the spray nozzle of the comparative example, and is a graph showing the distribution state of the spray material at a predetermined distance from the nozzle outlet.

Hereinafter, a spray nozzle according to a first embodiment of the present invention will be described with reference to the accompanying drawings.

The spray nozzle according to this embodiment is suitably used in a spray construction method using mortar as a spray material. Specifically, after preparing mortar by mixing cement, aggregate, water, etc., the mortar is pressurized with a pump, etc., and is forced through a hose and sprayed onto the construction surface of a concrete structure, etc. In the wet mortar spraying method, it is used, for example, by being attached to the tip of the hose.

As shown in FIGS. 1 and 2, the spray nozzle 1 according to the present embodiment includes, in order from the upstream side in the mortar flow direction, a connecting portion 10 that is joined to a distal end portion (not shown) of a hose through which mortar is pumped. , a protrusion installation part (cylindrical body) 20 extending downstream of the connecting part 10, a tapered part 30 extending downstream of the protrusion installation part 20, and a tapered part 30 extending downstream of the tapered part. and a distal end portion 40. The mortar flows into the spray nozzle 1 through the tip of a hose or the like connected to the connecting part, passes through the protrusion installation part 20, the tapered part 30, and the tip 40, and then is applied from the opening at the tip of the tip 40. It is discharged towards the surface.

In the spray nozzle 1 according to the present embodiment, the connecting portion 10, the protrusion installation portion 20, the tapered portion 30, and the tip portion 40 are each formed into a cylindrical shape and have a flow path through which mortar can flow. There is. The flow path has a circular cross section perpendicular to the axial direction, except for a region provided with a protrusion described later. The connecting part 10 is configured such that a connecting jig attached to the tip of the hose can be inserted into the inside of the connecting part, so that the flow path of the hose tip and the flow path of the protrusion installation part 20 are smooth. It is configured to be continuous.

In the following description, the direction along a virtual center line passing through the center of the spray nozzle is referred to as the axial direction, the direction intersecting the center line in a plan view from the axial direction is the radial direction, and the direction in the plan view is referred to as the radial direction. The direction of rotation around the center line will be referred to as the circumferential direction. Further, the upstream side in the flow direction of mortar may be simply referred to as the upstream side, and the downstream side (discharge side) in the flow direction of mortar may be simply referred to as the downstream side.

As shown in FIGS. 1 and 2, the spray nozzle 1 according to the present embodiment includes three protrusions 21 at positions corresponding to the protrusion installation portions 20 of the flow path, and specifically, A first protrusion 21a, a second protrusion 21b, and a third protrusion 21c are provided in order from the upstream side. Each protrusion 21 has a shape that protrudes radially inward from the inner circumferential surface of the cylindrical protrusion installation part 20 that constitutes a mortar flow path.

The three protrusions 21 in this embodiment are independent of each other, in other words, the peripheral edge of each protrusion 21 reaches the inner circumferential surface of the protrusion installation part 20, and the protrusions 21 are spaced apart from each other. The three protrusions 21 in this embodiment are arranged spirally on the inner peripheral surface of the cylindrical protrusion installation part (cylindrical body) 20. That is, the three protrusions 21 are arranged at positions spaced apart in the axial direction and also spaced apart in the circumferential direction. Specifically, as shown in FIG. 3, the three protrusions 21 are arranged at positions shifted in the circumferential direction by 120 degrees around the center line of the spray nozzle when viewed from the axial upstream side. There is. That is, the first protrusion 21a located on the most upstream side is arranged in the 2 o'clock direction (top right in FIG. 3) with respect to the center line of the spray nozzle, and is arranged next to the first protrusion 21a on the downstream side. The second protrusion 21b is also arranged in the 6 o'clock direction (downward in FIG. 3), and the third protrusion 21c arranged downstream next to the second protrusion 21b is also arranged in the 10 o'clock direction (downward in FIG. 3). (upper left in FIG. 3).

As shown in FIG. 2, each protrusion 21 has a first slope 211 facing upstream and a second slope 212 facing downstream. The first inclined surface 211 and the second inclined surface 212 in this embodiment each have a conical shape whose center line is substantially parallel to the axial direction of the protrusion installation part 20, and whose center line is the inner circumferential surface of the protrusion installation part 20. It is located above. In other words, the first inclined surface 211 and the second inclined surface 212 of each protrusion 21 are in a state where a part of the cone protrudes inward from the inner peripheral surface of the protrusion installation part 20 and blocks a part of the flow path. ing.
That is, in this embodiment, the first inclined surface 211 functions as an inclined portion whose cross-sectional area increases toward the downstream side of the flow path. Note that the cross-sectional area here means the area of the area surrounded by the outer contour line and the extension line (arc) of the inner peripheral surface in the radial cross section of the protrusion, and the area inside the cross section (the area of the protrusion). Even if the inside is hollow, it is included in the area.

With the above configuration, the radial cross-sectional area of each protrusion 21 is configured to increase toward the downstream side in the upstream portion (the portion corresponding to the first inclined surface 211) of the protrusion 21. . On the contrary, in the downstream portion of each protrusion 21 (the portion corresponding to the second inclined surface 212), the radial cross-sectional area of the protrusion 21 is configured to become smaller toward the downstream side.

The height r2 of the protrusion 21, that is, the height in the radial direction of the protrusion 21 from the inner circumferential surface in the axial cross section of the protrusion installation part 20 is configured to be approximately the same as the flow path radius in the protrusion installation part 20. be done. Specifically, the ratio (r2/D) of the height r2 of the protrusion 21 to the inner diameter D of the flow path is preferably 0.35 or more and 0.55 or less. With this configuration, the effect of the protrusion 21 can be more easily exerted. In this embodiment, the height of the protrusion 21 is equal to the radius of the bottom surface of the cone forming the first inclined surface 211 and the second inclined surface 212.

Further, as shown in FIG. 2, when viewed in an axial cross section passing through the center of the protrusion 21, the length of the protrusion 21 relative to the axial length d1 from the upstream tip to the downstream tip of the protrusion 21 is The ratio of height r2 (r2/d1) is preferably 0.4 or more and 2.5 or less. With this configuration, the effect of installing the protrusion 21 can be more easily exerted.

Furthermore, the inner periphery of the protruding part 21 has a distance y between the adjacent protruding parts 21, for example, a distance y from the upstream end of the first protruding part 21a to the upstream end of the adjacent second protruding part 21b. The ratio (y/r2) to the height r2 from the surface is preferably 1 or more and 3.5 or less. With this configuration, the effect of installing the protrusion 21 can be more easily exerted.

The specific shape of the protrusion 21 in this embodiment is such that the apex angle of the cone forming the first inclined surface 211 is smaller than the apex angle of the cone forming the second inclined surface 212. In other words, the slope on the upstream side is gentler than the slope on the downstream side. Moreover, the space between the first inclined surface 211 and the second inclined surface 212 is configured as a part of a cylinder whose radial cross section is the same along the axial direction.

By providing the protrusion installation part 20 having such a configuration, when mortar passes through the protrusion installation part 20, the mortar first collides with the first protrusion part 21a. The flow direction of the mortar that has collided with the first protrusion 21a is changed by the first inclined surface 211, and specifically, the mortar has a velocity component that extends radially from the first inclined surface 211 when viewed from the axial direction. Become what you have.

The mortar that has passed through the first protrusion 21a then sequentially collides with the second protrusion 21b and the third protrusion 21c, and passes through the protrusion installation part 20 while receiving the same action from each protrusion as the first protrusion. That will happen. As described above, since the first protrusion 21a, the second protrusion 21b, and the third protrusion 21c are arranged spirally on the inner peripheral surface of the protrusion installation part 20, the protrusion installation part 20 can be The mortar that has passed also has a velocity component in the helical direction as a whole.

That is, the mortar that has passed through the protrusion installation part 20 has a uniform flow velocity distribution within the flow path, and has a velocity component in a spiral direction. As a result, the mortar discharged from the spray nozzle according to this embodiment has a uniform mortar concentration from the center to the outside, making it possible to apply mortar with a uniform thickness to the construction surface.

Moreover, since each of the protrusions 21 has an inclined part whose cross-sectional area increases toward the downstream side, the resistance acting on the mortar passing through the protrusion installation part 20 is small, and the pressure loss of the mortar is unlikely to increase. There is an effect.

The tapered portion 30 disposed on the downstream side of the protrusion installation portion 20 has a tapered shape that is continuous with the protrusion installation portion 20 and has a flow passage cross-sectional area that decreases toward the downstream side. Specifically, in the axial cross section shown in FIG. 2, the angle between the opposing inner circumferential surfaces is preferably 5 to 15 degrees.

Further, the spray nozzle in this embodiment is provided with a distal end portion 40 on the downstream side of the tapered portion 30, the inner diameter of the flow path being constant along the axial direction. The inner diameter of the tip portion 40 is preferably in the range of 0.5 to 0.7 with respect to the inner diameter of the protrusion installation portion 20. Further, the tip of the tip portion 40 serves as a discharge port through which the spraying material is discharged. The distance x from the protrusion 21 provided at the most downstream position to the discharge port is preferably in a range where the ratio (x/D) to the channel inner diameter D of the protrusion installation part 20 is 5 or more and 10 or less.

Note that the shape of the protrusion is not limited to the shape of the above embodiment, but can be any shape. Specifically, a sphere, a spheroid (long sphere), a pyramid, a cone, or any shape similar to these may be used, and a combination of some or more of these may be used.

For example, as shown in FIG. 4, the protrusion in the present invention may have a spheroidal shape (roughly spherical with a slightly shorter diameter in the axial direction). Further, as shown in FIG. 5, the protrusion in the present invention may have a triangular pyramid shape with the bottom facing downstream and the apex facing upstream.

The spraying construction method as one embodiment is a construction method in which a spraying material is sprayed onto the construction surface of a construction target using a spraying nozzle having the above configuration. Specifically, there is a material preparation process in which the spraying material is prepared, a pressure feeding process in which the prepared spraying material is pressurized with a pump, etc., and sent to the construction site via a pressure feeding route such as a hose, and a material is attached to the tip of the pressure feeding route. A so-called wet spraying construction method can be adopted, which includes a spraying step of discharging a spraying material through a spraying nozzle having the above configuration and spraying it onto the construction surface of an object to be constructed, such as a concrete structure.

In addition, other embodiments include a powder material preparation step in which a powder material is prepared by mixing materials other than water, and a powder material preparation step in which the powder material is pumped to a construction site via a pumping route such as a hose. A material pumping step, a water pumping step of pumping water to the construction site via a pumping route separate from the powder material, and a mixing step of mixing the powder material and water before the spray nozzle. It is also possible to adopt a so-called dry spraying method, which includes a spraying step of spraying a spraying material onto a construction surface through a spraying nozzle having the above-mentioned configuration.

As the spraying material, slurry spraying materials containing inorganic materials such as various cements, gypsum, fine aggregates, coarse aggregates, etc., or organic materials such as fibers, wood materials, polymers, etc. can be suitably used, and in particular, Mortar can be suitably used.

It should be noted that as for the equipment used in each step in the above-mentioned spraying method, any equipment known in this field can be employed, except for the spray nozzle, and a detailed explanation thereof will be omitted.

Next, the results of evaluating the spray performance of the spray nozzle according to the embodiment of the present invention using simulation will be described. The spray nozzles that were subjected to the simulation were those having a protrusion in the shape shown in Figs. 1 to 3 (hereinafter also referred to as a top shape) as described above, and one having an ellipsoidal protrusion as shown in Fig. 4. and one with the triangular pyramid-shaped protrusion shown in FIG. Regarding spray nozzles equipped with a top-shaped protrusion, evaluations were conducted in Examples 1 to 9 using the values shown in Table 1 below for the dimensions of each part shown in FIG.
On the other hand, as a comparative example, a spray nozzle in which all the protrusions were removed from the spray nozzle of the present embodiment shown in FIGS. 1 to 3 was used and evaluated.

The simulation results are shown in Table 1 above. According to the results of the simulation, it can be seen that the average particle velocity at the nozzle exit of any of the spray nozzles of Examples 1 to 9 is lower than that of the spray nozzle of the comparative example that does not have a protrusion.

In addition, for the spray nozzles of Example 5 (top type), Example 10 (ellipsoid), Example 11 (triangular pyramid), and Comparative Example (no protrusion), 0.2 m, 0.4 m from the nozzle outlet, and 0.4 m from the nozzle exit, respectively. The results of calculating the particle distribution in a plane perpendicular to the axial direction at 0.6 m are shown in FIGS. 7 to 10. In the spray nozzles of Examples 5, 10, and 11, as shown in FIGS. 7, 8, and 9, the particles discharged from the nozzle outlet were distributed uniformly in a plane perpendicular to the axial direction. You can see that it is spreading. On the other hand, in the spray nozzle of the comparative example in which no protrusion was provided, as shown in FIG. 10, it can be seen that the particles discharged from the nozzle outlet were distributed biased toward the center.

In this manner, in the spray nozzle of this embodiment, the average particle velocity of the spray material discharged from the nozzle is reduced, and the material is discharged with a concentration distribution that spreads uniformly over the construction surface. Therefore, it is possible to efficiently apply a thick layer to the construction surface without blowing away the sprayed material.

It should be noted that the spray nozzle and spray construction method according to the present invention are not limited to the above-described embodiments, and it goes without saying that various changes can be made without departing from the gist of the present invention.

For example, in the spray nozzle of the above embodiment, a case has been described in which the connecting portion 10, the protrusion installation portion 20, the tapered portion 30, and the tip portion 40 are integrally formed as one continuous member. The structure is not limited, and it is also possible to combine a plurality of members to form a spray nozzle having the above structure.

Further, in the above embodiment, a spray nozzle including three protrusions has been described, but the present invention is not limited to such a configuration, and may include four or more protrusions.

DESCRIPTION OF SYMBOLS 1... Spray nozzle, 10... Connection part, 20... Protrusion installation part, 30... Taper part, 40... Tip part, 21... Protrusion part

Claims (7)

A spray nozzle for spraying slurry-like spray material,
A cylindrical body with a flow path formed inside;
a plurality of independent protrusions that protrude from the inner circumferential surface of the cylindrical body toward the inside of the cylindrical body;
The spray nozzle is characterized in that the plurality of protrusions are arranged spirally on the inner peripheral surface of the cylindrical body. The spray nozzle according to claim 1, wherein the plurality of protrusions are arranged at equal intervals on the inner peripheral surface of the cylindrical body when viewed from the center line direction of the cylindrical body. The spray nozzle according to claim 1, wherein the plurality of protrusions include three protrusions arranged at an interval of 120 degrees on the inner circumferential surface of the cylindrical body when viewed from the center line direction of the cylindrical body. The spray nozzle according to any one of claims 1 to 3, wherein a ratio (r2/D) of the height r2 of the protrusion to the inner diameter D of the cylindrical body is 0.3 or more and 0.55 or less. The spray nozzle according to any one of claims 1 to 4, wherein each of the protruding parts has an inclined part whose cross-sectional area increases toward the downstream side of the flow path. The spray nozzle according to claim 5, wherein the inclined portion has a conical shape, and a center line of the conical shape is arranged substantially parallel to a center line of the cylinder. A spraying method characterized by spraying a spraying material using the spraying nozzle according to any one of claims 1 to 6.