JP7371835B2 - Slurry fluidization equipment - Google Patents

Description

TECHNICAL FIELD The present invention relates to a slurry fluidization device.

In recent years, it has been strongly desired to form a dense thermal sprayed coating with excellent heat resistance and coating strength on the surface of a coating material while suppressing the occurrence of voids and cracks. As a method for this purpose, Patent Document 1 discloses the use of heat-resistant fine particles as a thermal spray material. Specifically, a fine particle-containing slurry is created by dispersing fine particles in an organic solvent, and this is introduced into a combustion flame in an atomized state, thereby eliminating the organic solvent and spraying the fine particles onto the material to be thermally sprayed. do.

Patent Document 2 discloses that a slurry containing fine particles, which is pressure-fed from a syringe, is supplied via piping to a spraying device that atomizes the slurry.

Japanese Patent Application Publication No. 2014-213214 Japanese Patent Application Publication No. 2018-168414

Slurry containing fine particles has a special rheological property called thixotropy (also called thixotropy), which means that it becomes fluid when a shearing force is applied to it and maintains its shape when no load is applied. ing. However, the fluidity of the fine particle-containing slurry that is force-fed into the pipe from the syringe is easily reduced even if it is allowed to stand still for just a few minutes without applying any shearing force. Therefore, it is desired to convey the fine particle-containing slurry that has been pressure-fed into the pipe to the spraying device while maintaining its high fluidity.

An object of the present invention is to provide a slurry fluidization device that can improve the fluidity of a slurry containing fine particles that is pumped into a pipe.

The inventor of the present application considered the following regarding the decrease in fluidity of the fine particle-containing slurry over time. In other words, a thixotropic fluid (non-Newtonian fluid) is a Newtonian fluid conceptually shown in FIG. 15(a), in which the amount of particles dispersed in a solvent is increased, as shown in FIG. 15(b). Immediately after the fine particles are dispersed, the fine particles are close to each other, and the fine particle-containing slurry exhibits fluidity although it has a high viscosity. It was thought that by leaving this state for several minutes, the fine particles would be bonded by intermolecular force as shown in FIG. 15(c), and the fluidity of the fine particle-containing slurry would be reduced.

On the other hand, as described above, by applying a shearing force to the fine particle-containing slurry, it returns to the state shown in FIG. 15(b). Therefore, we came up with the idea of generating a shearing force in the pipe so as to increase or maintain the fluidity of the fine particle-containing slurry that is pumped through the pipe. The present invention is based on this new idea.

The present invention
Piping through which slurry containing fine particles is pumped;
a rod-shaped member that is fitted inside the piping in the axial direction, and has an inclined groove extending in a direction inclined with respect to the axial direction on its outer circumference;
has
The inclined groove penetrates the rod-shaped member from one end to the other end in the axial direction,
The rod-shaped member is
a plurality of large diameter portions that are spaced apart in the axial direction and have the inclined grooves and male threads formed therein;
a narrow diameter portion that is located between the pair of large diameter portions adjacent to each other in the axial direction and is thinner than the large diameter portion;
It has
The piping has a cylindrical nipple into which the rod-shaped member is inserted, and a slurry outlet socket connected to an end of the nipple in the axial direction,
The slurry outlet socket is a cylindrical member having a hole penetrating in the pumping direction in which the slurry containing fine particles is pumped, and has a diameter larger than the hole at the mouth on the upstream side in the pumping direction, and the nipple has a counterbore to which the end portion of is connected;
The large diameter portion has an outer peripheral portion formed by the male screw extending in a direction inclined to one side in the left-right direction toward the downstream side in the pumping direction of the fine particle-containing slurry,
The rod-shaped member is fixed to the hole of the slurry outlet socket in a cantilevered state by screwing the male thread into the mouth of the hole of the slurry outlet socket ,
The piping is further provided with a slurry filtering section,
The slurry filtering section is composed of a net-like mesh member,
The slurry filtering section is provided in plurality,
The plurality of slurry filtering sections provide a slurry fluidization device in which the openings of the mesh member become finer toward the downstream side in the pumping direction of the fine particle-containing slurry.

According to the present invention, since the rod-shaped member is inserted into the pipe, the slurry containing fine particles is pumped through the inclined groove from the upstream side of the rod-shaped member to the downstream side. Since the inclined groove is inclined with respect to the axial direction of the piping, that is, with respect to the pumping direction of the fine particle-containing slurry, the fine particle-containing slurry is guided in the inclined groove in a direction inclined with respect to the pumping direction. As a result, shearing force is generated in the fine particle-containing slurry that is pumped into the inclined grooves, making it easier to fluidize the slurry.

Further, in the particulate-containing slurry that is pumped through the pipe, a portion of the slurry that is pumped along the inner wall of the pipe is likely to be decelerated, creating a velocity gradient in the vicinity of the inner wall. Due to the velocity gradient, a shearing force is generated in the fine particle-containing slurry in the vicinity of the inner wall surface of the pipe, making it easy to fluidize. Here, since the slanted groove has a smaller flow path cross section than the piping, the velocity gradient described above is likely to occur over the entire cross section of the flow path, and the entire particulate-containing slurry within the slanted groove can be easily fluidized.

Therefore, by force-feeding the particulate-containing slurry into the inclined groove, shearing force is generated in the particulate-containing slurry being pumped through the pipe, and its fluidity can be easily increased or maintained. In addition, the pressure of the particulate-containing slurry that is pumped through the piping is used to guide it through the inclined grooves, and there is no need to install a screw or the like in the piping to stir the particulate-containing slurry, and no power is required. It is not necessary and saves energy. In addition, since the slurry fluidization device can be configured simply and compactly, it can be easily installed in piping and has a high degree of freedom in arrangement.
In addition, since the large-diameter part of the rod-shaped member is configured with a male thread , the area where the inner wall surface of the nipple and the outer surface of the rod-shaped member inserted inside the nipple are fitted is minimized, so there is no need for piping. Sticking of the rod-shaped member is suppressed. Therefore, the workability of attaching and detaching the rod-shaped member to and from the pipe is improved. In particular, the above effect is suitably exhibited when fluidizing a slurry containing fine particles, which tends to cause problems such as fine particles getting caught between a rod-shaped member and piping, making removal difficult. Ru.

Preferably, a plurality of the inclined grooves are formed.

According to this configuration, the fine particle-containing slurry can be pumped while increasing the flow rate while suppressing an excessive pressure increase caused by pumping the slurry into the inclined groove whose cross-sectional area is smaller than that of the piping. This makes it easy to stably fluidize the fine particle-containing slurry.

Generally, as the inclined groove becomes longer, the direction in which the fine particle-containing slurry is pumped in the inclined groove tends to follow the extending direction of the inclined groove, and the shearing force generated in the fine particle-containing slurry becomes weaker. According to this configuration, since the inclined grooves are formed in the large diameter portions that are provided intermittently, the inclined grooves are prevented from becoming excessively long, and the shearing force generated in the fine particle-containing slurry is weakened. It is easy to end the guidance by the inclined groove in the front. Therefore, high shearing force is intermittently generated in the fine particle-containing slurry by the inclined grooves that are intermittently formed in the pumping direction of the fine particle-containing slurry.

In addition, the fine particle-containing slurry fluidized by each of the plurality of inclined grooves flows into the space defined between the narrow diameter section and the inner wall surface of the pipe and is mixed and stirred. A shearing force is generated in the slurry containing the slurry, and as a result, it is easy to maintain and increase the fluidity of the slurry containing fine particles generated by the inclined grooves.

Therefore, the inclined grooves and the narrow diameter portions in the plurality of large diameter portions can easily maintain a high shearing force generated in the fine particle-containing slurry that is pumped from the upstream side to the downstream side of the rod-shaped member, making the fine particle-containing slurry even more effective. Easy to liquefy.

Preferably, the pair of inclined grooves formed in each of the pair of large diameter portions adjacent to each other in the axial direction are inclined in directions opposite to each other with respect to the axial direction.

According to this configuration, since the pair of axially adjacent inclined grooves are inclined in opposite directions, the flow direction of the fine particle-containing slurry is changed when switching from the upstream inclined groove to the downstream inclined groove. This tends to cause a large change in the shearing force generated in the slurry containing fine particles. This facilitates further increasing the fluidity of the fine particle-containing slurry.

Preferably, among the plurality of large diameter portions, the number of inclined grooves formed in the large diameter portion located on the upstream side in the axial direction is greater than the number of inclined grooves formed in the large diameter portion located on the downstream side. The number of inclined grooves formed is equal to or less than the number of the inclined grooves formed.

According to this configuration, as the fine particle-containing slurry is pumped from the upstream side to the downstream side, the amount to be fluidized increases. This gradually reduces the viscosity of the fine particle-containing slurry, making it easier to efficiently fluidize the fine particle-containing slurry.

Preferably, the piping further includes a slurry filtering section,
The slurry filtering section is made of a net-like mesh member.

According to this configuration, the fine particle-containing slurry is filtered by the slurry strainer, so that the fine particle-containing slurry is suppressed from being lumped together and being pumped. This facilitates further promoting the flow of the slurry containing fine particles.

Further, preferably, a plurality of the slurry filtering sections are provided,
In the plurality of slurry filtering sections, the openings of the mesh members become finer toward the downstream side in the pumping direction of the fine particle-containing slurry.

According to this configuration, as the fine particle-containing slurry is pumped from the upstream side to the downstream side, it is gradually filtered finely. This makes it easier to further promote fluidization while suppressing an increase in the pressure of the fine particle-containing slurry being pumped.

Preferably, the slurry filtering section is composed of a plurality of the mesh members stacked in mutually different phases.

According to this configuration, the slurry filtering section is composed of a plurality of mesh members stacked in different phases, so that the flow path is twisted from the opening of one mesh member to the opening of the other mesh member. It is composed of As a result, the fine particle-containing slurry is filtered while being twisted by the slurry filtration section, which generates shearing force and increases fluidity.

Further, by constructing the slurry filtering section with a plurality of mesh members laminated with mutually different phases, the openings of the slurry filtering section become finer, so that the flow of the fine particle-containing slurry is easily promoted.

Further, preferably, three or more slurry strainers are provided at intervals in the axial direction,
The distance between the slurry strainers is longer on the upstream side than on the downstream side.

According to this configuration, the particulate-containing slurry that is filtered in the upstream slurry filtration part has a higher viscosity than the particulate-containing slurry that is further filtered in the downstream slurry filtration part. Therefore, the space between the particulate-containing slurry that has passed through the upstream slurry filtration section, which has a relatively high viscosity, flows into the slurry filtration section located downstream, is configured to be relatively long. It is easy to sufficiently mix and stir a fine particle-containing slurry with high viscosity. This further increases the fluidity of the fine particle-containing slurry.

According to the present invention, the fluidity of the fine particle-containing slurry that is pressure-fed into the pipe can be improved.

1 is a schematic diagram of a thermal spray system according to an embodiment of the present invention. 2 is a schematic diagram showing one mode of operation of the thermal spray system of FIG. 1. FIG. FIG. 2 is a schematic diagram showing another mode of operation of the thermal spray system of FIG. 1; FIG. 2 is a cross-sectional view of the slurry fluidization device taken along the slurry pumping direction. A cross-sectional view taken along the line IV-IV in FIG. 3. FIG. 4 is a cross-sectional view taken along line VV in FIG. 3. A cross-sectional view taken along line VI-VI in FIG. 3. A cross-sectional view taken along line VII-VII in FIG. 3. A sectional view taken along the line VIII-VIII in FIG. 3. A developed view of the outer periphery of the slurry mixer. FIG. 3 is a conceptual diagram showing fluidization of fine particle-containing slurry in an inclined groove. FIG. 3 is a conceptual diagram showing stirring of a slurry containing fine particles in a space on the outer peripheral side of a narrow diameter portion. FIG. 2 is a conceptual diagram showing a velocity gradient of a slurry containing fine particles in a cross section of an inclined groove. The conceptual diagram which shows the velocity gradient of the flow velocity of the fine particle containing slurry in the cross section of piping. FIG. 3 is a developed view of the outer periphery of the slurry mixer according to Example 2. A conceptual diagram showing changes in fluidity of a slurry containing fine particles.

Embodiments of the present invention will be described below with reference to the accompanying drawings. Note that the following description is essentially just an example, and is not intended to limit the present invention, its applications, or its uses. Further, the drawings are schematic, and the ratio of each distance is different from the actual one.

FIG. 1 is a schematic diagram of a thermal spray system 1 according to an embodiment of the present invention. Thermal spraying system 1 uses a fine particle-containing slurry S (hereinafter referred to as slurry S) in which fine particles (for example, aluminum oxide fine particles) are dispersed in an organic solvent (for example, liquid acrylic resin) as a thermal spraying material, and coats the fine particles. Spray on thermal spray material Z. Thermal spraying system 1 includes a slurry supply device 3 that supplies slurry S, a slurry fluidization device 4 that fluidizes slurry S, a slurry spraying device 5 that atomizes slurry S, and a slurry thermal spraying device 6 that sprays slurry S. and in order from the upstream side along the conveyance direction of the slurry S.

The thermal spraying system 1 further includes a slurry storage tank 2 that stores slurry S to be supplied to the slurry supply device 3, a slurry pipe 7 that connects each of the devices 2 to 6 and transports the slurry S, and a slurry pipe 7. It has first and second three-way valves 8a, 8b and a pressure sensor 9 provided in the three-way valve.

The slurry storage tank 2 is a container with a bottom and a lid, and the slurry S is stored inside. A screw or the like may be provided inside the slurry storage tank 2 to stir the stored slurry S and apply shearing force to it. The slurry storage tank 2 is connected to a first three-way valve 8a via a first slurry pipe 7a.

The slurry supply device 3 includes a syringe 3a and a plunger 3b disposed within the syringe 3a so as to be able to move forward and backward. The front end of the syringe 3a is connected to a first three-way valve 8a via a second slurry pipe 7b. By moving the plunger 3b forward, the slurry S filled in the syringe 3a is fed under pressure to the second slurry pipe 7b. In the following description, the direction in which the slurry S filled here is pumped from the syringe 3a will be referred to as the pumping direction F.

The slurry fluidization device 4 is provided in the middle of the third slurry pipe 7c that connects the first and second three-way valves 8a and 8b. The slurry fluidization device 4 fluidizes the slurry S pumped through the third slurry pipe 7c. In this specification, fluidizing the slurry S means reducing the viscosity of the slurry S to make it easier to flow.

Furthermore, a pressure sensor 9 for measuring the pressure of the fluidized slurry S is provided in the third slurry pipe 7c on the downstream side of the slurry fluidization device 4.

The slurry spray device 5 is provided downstream of the second three-way valve 8b, and atomizes the slurry S supplied from the second three-way valve 8b via the fourth slurry pipe 7d. The slurry spraying device 6 is provided immediately downstream of and adjacent to the slurry spraying device 5, and introduces the atomized slurry S into a gas flame and sprays it toward the material Z to be thermally sprayed. The gas flame generated by the slurry thermal spraying device 6 causes the organic solvent in the slurry S to disappear, and particles are thermally sprayed onto the material Z to be thermally sprayed.

First to third slurry pipes 7a to 7c are connected to the first three-way valve 8a. The first three-way valve 8a has a first valve position (FIG. 1) where the second and third slurry pipes 7b and 7c communicate with each other, and a second valve position (Fig. 1) where the first and second slurry pipes 7a and 7b communicate with each other. 2A).

As shown in FIG. 1, by positioning the first three-way valve 8a at the first valve position and moving the plunger 3b forward within the syringe 3a, the slurry S is force-fed from the slurry supply device 3 to the second and third valve positions. 3 slurry pipes 7b and 7c in the pumping direction F. Furthermore, as shown in FIG. 2A, by switching the first three-way valve 8a to the second valve position and retracting the plunger 3b within the syringe 3a, the slurry S is replenished from the slurry storage tank 2 into the syringe 3a. Ru.

In addition to the third and fourth slurry pipes 7c and 7d, a fifth slurry pipe 7e communicating with the slurry storage tank 2 is further connected to the second three-way valve 8b. The second three-way valve 8b has a first valve position (FIG. 1) where the third and fourth slurry pipes 7c and 7d communicate with each other, and a second valve position (FIG. 2B) where the third and fifth slurry pipes 7c and 7e communicate with each other. ).

As shown in FIG. 1, by positioning the second three-way valve 8b at the first valve position, the slurry S fluidized by the slurry fluidization device 4 is supplied to the slurry spraying device 5. Further, as shown in FIG. 2B, by switching the second three-way valve 8b to the second valve position, the slurry S that has passed through the slurry fluidization device 4 is returned to the slurry storage tank 2.

At the initial stage of starting up the operation of the thermal spray system 1 or when restarting after stopping for several minutes, the fluidity of the slurry S fluidized by the slurry fluidizer 4 is not sufficient and the pressure of the slurry S is stabilized. It may not. In this case, even if the slurry S whose pressure is not stable is supplied to the slurry spraying device 5, it is difficult to uniformly atomize the slurry S (that is, the spray diameter tends to vary), and the quality of the thermal sprayed coating formed by thermal spraying is difficult to stabilize.

In this embodiment, based on the pressure of the slurry S measured by the pressure sensor 9, the second By positioning the three-way valve 8b in the second valve position, the slurry S is returned to the slurry storage tank 2.

On the other hand, if it is confirmed that the pressure of the slurry S is stabilized within the predetermined pressure range, based on the pressure of the slurry S measured by the pressure sensor 9, the second three-way valve 8b is switched to the first valve position. Accordingly, the slurry S is supplied to the slurry spraying device 5. By supplying the slurry S with stable pressure to the slurry spraying device 5, it is easy to uniformly spray the slurry S to be atomized, and it is easy to improve the quality of the thermal sprayed coating formed by thermal spraying.

The slurry fluidization device 4 will be explained below.

FIG. 3 is a cross-sectional view of the slurry fluidization device 4 along the pumping direction F. The slurry fluidization device 4 includes a first slurry fluidization section 20 and a second slurry fluidization section 40, which are provided in order from the upstream side in the pumping direction F.

The first slurry fluidization section 20 is defined between a cylindrical socket 21, a pair of hollow bushings 22 screwed in the axial direction on both sides of the cylindrical socket 21, and a pair of bushings 22 inside the socket 21. A slurry filtering section 23 is provided in the space where the slurry is filtered. The pair of bushings 22 and socket 21 are fastened together using a tapered screw structure, and are fastened while maintaining a seal between them. The upstream bushing 22 has an inner diameter connected to a slurry inlet pipe 28 that communicates with the first three-way valve 8a.

The slurry filtering section 23 is configured by laminating a plurality of mesh members 24 and a plurality of spacers 27. The mesh member 24 is made by weaving wire into a net shape, and includes a coarse mesh member 25 with relatively coarse openings and a fine mesh member 26 with relatively fine openings. The spacer 27 is a so-called flat washer, and is an annular member having an opening 27a in the thickness direction at the center.

The coarse mesh member 25 is made of, for example, stainless steel wire (SUS304) with a wire diameter of 0.6 mm woven into 12 meshes (number of openings per inch). The fine mesh member 26 is made of, for example, stainless steel wire (SUS304) with a wire diameter of 0.35 mm woven into 30 meshes.

The slurry filtering section 23 includes, in order from the upstream side in the pumping direction F, an upstream slurry filtering section 23A, an intermediate slurry filtering section 23B, and a downstream slurry filtering section 23C. On the other hand, the mesh of the slurry strainer 23 (that is, the openings of the mesh member 24) is configured to become finer.

FIG. 4 is a cross-sectional view of the first slurry fluidization section 20 taken along the line IV-IV in FIG. 3, and shows the upstream slurry filtering section 23A viewed from the downstream side. Referring also to FIG. 4, the upstream slurry filtering section 23A is constructed by laminating two coarse mesh members 25 and two spacers 27 interposed between them in the pumping direction F. has been done.

FIG. 5 is a sectional view of the first slurry fluidization section 20 taken along the line VV in FIG. 3, and shows the downstream slurry filtering section 23C as seen from the downstream side. Referring also to FIG. 5, the downstream slurry filtering section 23C is constructed by laminating two fine mesh members 26 and a spacer 27 interposed between them in the pumping direction F. .

FIG. 6 is a cross-sectional view of the first slurry fluidization section 20 taken along line VI-VI in FIG. 3, and shows the intermediate slurry filtering section 23B seen from the downstream side. Referring also to FIG. 6, the intermediate slurry filtering section 23B is constructed by laminating two coarse mesh members 25 with openings having different phases. In order to make the phases of the openings different, one coarse mesh member 25 may be laminated by rotating (for example, 45°) within a plane with respect to the other so that the wire directions are different from each other (FIG. 6). Alternatively, although not shown in the drawings, one coarse mesh member 25 may be moved vertically and horizontally in parallel with respect to the other in a plane so that the openings thereof are shifted from each other.

As a result, the size of the opening of the intermediate slurry filtering section 28B formed by laminating the two coarse mesh members 25 is set to be smaller than that of the coarse mesh member 25, but larger than that of the fine mesh member 26. .

As shown in FIG. 3, spacers 27 are interposed and stacked between each of the slurry strainers 23A to 23C. Further, spacers 27 are also stacked on the upstream side of the upstream slurry strainer 23A.

The second slurry fluidization section 40 includes a cylindrical nipple 41, a slurry mixer 42 fitted inside the nipple 41 in the axial direction, and a slurry outlet socket 55 located on the downstream side of the nipple 41. ing. The nipple 41 is screwed into the inner diameter of the bushing 22 on the downstream side of the first slurry fluidization section 20 at its upstream end.

The slurry outlet socket 55 is a cylindrical member having a hole 56 penetrating in the pumping direction F. A counterbore portion 57 whose diameter is larger than that of the hole portion 56 is formed at the mouth of the hole portion 56 on the upstream side. The downstream end of the nipple 41 is screwed into the counterbore 57 and connected thereto.

A slurry outlet pipe 58 (see FIG. 1) is connected to the downstream end of the slurry outlet socket 55. As described above, the slurry fluidization device 4 has the slurry inlet pipe 28 connected to the upstream end thereof, which communicates with the first three-way valve 8a. Therefore, the third slurry pipe 7c connecting between the first and second three-way valves 8a and 8b includes the slurry inlet pipe 28, the socket 21, the pair of bushings 22, the nipple 41, the slurry outlet socket 55, and the slurry It is configured by an outlet pipe 58.

The slurry mixer 42 is a rod-shaped member extending in the pumping direction F, and has a plurality of large diameter portions 43 and a plurality of small diameter portions 47 that are thinner than the large diameter portions 43. The outer circumferential portion of the large diameter portion 43 is configured with a male thread. The outer diameter D1 of the large diameter portion 43 (specifically, the crest of the male thread) is set slightly larger than the inner diameter D2 of the nipple 41, and specifically, the difference between the outer diameter D1 and the inner diameter D2 is The range is set to 0.1 mm±0.05 mm. This makes it easy to set a very small gap between the outer circumferential portion of the large diameter portion 43 excluding the inclined groove 48 and the inner diameter portion of the nipple 41, and the flow of the slurry S into the gap is suppressed. Therefore, it is easy to cause the slurry S to flow into the inclined grooves 48.

The slurry mixer 42 is screwed and fixed to the upstream mouth of the hole 56 at the downstream end. Therefore, the slurry mixer 42 is cantilevered into the hole 56 of the slurry outlet socket 55. Since the slurry mixer 42 is fixed to the slurry outlet socket 55, rotation of the slurry mixer 42 is suppressed by the flow of the slurry S guided in the inclined groove 48, as will be described later.

The plurality of large diameter portions 43 include, in order from the upstream side in the pumping direction F, an upstream large diameter portion 44, an intermediate large diameter portion 45, and a downstream large diameter portion 46. The plurality of large diameter portions 43 are spaced apart from each other in the axial direction, and the small diameter portion 47 is located between them. A plurality of inclined grooves 48 extending in a direction inclined in the circumferential direction toward the pumping direction F are formed in the outer peripheral portion of each of the plurality of large diameter portions 43.

FIG. 7 is a cross-sectional view of the upstream large diameter portion 44 perpendicular to the axial direction. As shown in FIG. 7, four upstream inclined grooves 49 are formed as the plurality of inclined grooves 48 in the upstream large diameter portion 44 at equal intervals in the circumferential direction. FIG. 8 is a cross-sectional view of the intermediate large diameter portion 45 orthogonal to the axial direction. As shown in FIG. 8, six intermediate inclined grooves 50 as the plurality of inclined grooves 48 are formed in the intermediate large diameter portion 45 at equal intervals in the circumferential direction. Although not shown, in the downstream large diameter portion 46, six downstream inclined grooves 51 are formed as a plurality of inclined grooves 48 at equal intervals in the circumferential direction, similarly to the intermediate large diameter portion 45.

Therefore, the number of upstream inclined grooves 49 formed is four, which is less than the number of intermediate inclined grooves 50 located downstream, which is six, and the number of intermediate inclined grooves 50 formed, which is six, is less than the number of intermediate inclined grooves 50 formed downstream. It is equal to six, which is the number of downstream inclined grooves 51 located on the side. Therefore, in the pumping direction F, the number of inclined grooves 48 located on the upstream side is set to be less than or equal to the number of inclined grooves 48 formed on the downstream side.

FIG. 9 is a developed view of the outer circumference of the slurry mixer 42, in which the inclined grooves 48 are hatched. As shown in FIG. 9, a pair of inclined grooves 48 formed in each of the large diameter portions 43 adjacent to each other in the pumping direction F are inclined in directions opposite to each other with respect to the pumping direction F. Specifically, in FIG. 9, toward the pumping direction F, the upstream inclined groove 49 is inclined downward, the intermediate inclined groove 50 on the downstream side is inclined upward, and the intermediate inclined groove 50 on the downstream side is inclined upward. The downstream inclined groove 51 is inclined downward. That is, the plurality of inclined grooves 48 are formed so as to extend in a zigzag shape toward the pumping direction F across the plurality of large diameter portions 43.

Hereinafter, the structure of the inclined groove 48 will be explained by taking the upstream inclined groove 49 as an example, but the same applies to the intermediate inclined groove 50 and the downstream inclined groove 51. As shown in FIG. 7, in this embodiment, the upstream inclined groove 49 has a rectangular cross-sectional shape, but various other cross-sectional shapes can be adopted, for example, a triangular shape, a semicircular shape, etc. It may be formed into a shape.

The groove width W of the upstream inclined groove 49 is set to be 1 mm or more and smaller than the radius R of the upstream large diameter portion 44 . Further, the groove depth H of the upstream inclined groove 49 is set to be 1 mm or more and 90% or less of the radius R of the upstream large diameter portion 44.

In the developed view in FIG. 9, the upstream inclined groove 49 penetrates the outer peripheral portion from the upstream end of the upstream large diameter portion 44 to the downstream end in a direction inclined at an inclination angle A with respect to the pumping direction F. It extends in a straight line. The inclination angle A is set to 5° or more and 85° or less. The upstream inclined groove 49 only needs to be inclined with respect to the pumping direction F, and may be bent or curved at the outer peripheral portion from the upstream end toward the downstream end.

Furthermore, since the upstream inclined groove 49 is inclined with respect to the pumping direction F, the length L1 along the extending direction is longer than the length L0 of the upstream large diameter portion 44 along the pumping direction F. long. Specifically, the length L1 of the upstream inclined groove 49 is 102% or more of the length L0 of the upstream large diameter portion 44, and the four upstream inclined grooves 49 formed in the upstream large diameter portion 44 The inclination angle A is set so that the total length of each length L1 is 310% or more of the length L0 of the upstream large diameter portion 44.

In this embodiment, the outer diameter of the narrow diameter portion 47 is set such that the outer circumferential surface 47a is at the same radial position as the bottom surface of the upstream inclined groove 49, as shown by the imaginary line in FIG. . However, the outer peripheral surface 47a of the narrow diameter portion 47 may be different from the groove bottom surface of the upstream inclined groove 49 in the radial direction.

The fluidizing action of the slurry S by the slurry fluidizing device 4 explained above will be explained.

As shown in FIG. 3 , the slurry S pumped by the slurry supply device 3 is conveyed in the pumping direction F and reaches the first slurry fluidization section 20 . At this time, the slurry S has a high viscosity and is conveyed in the form of a paste. In the first slurry fluidization section 20, the slurry S first reaches the upstream slurry filtering section 23A.

The upstream slurry filtering section 23A is composed of a pair of coarse mesh members 25, and two spacers 27 are interposed between them. Therefore, the slurry S that has been coarsely filtered by the coarse mesh member 25 on the upstream side is stirred and subjected to shearing force before flowing into the coarse mesh member 25 disposed on the downstream side. As a result, a portion of the slurry S that is different from the portion filtered by the coarse mesh member 25 on the upstream side is further filtered by the coarse mesh member 25 on the downstream side.

The slurry S filtered by the upstream slurry filtering section 23A reaches the intermediate slurry filtering section 23B. In the intermediate slurry filtering section 23B, a pair of coarse mesh members 25 are stacked with their phases shifted from each other. Therefore, when the slurry S passes through the intermediate slurry filtering section 23B, it is twisted from the coarse mesh member 25 on the upstream side to the coarse mesh member 25 on the downstream side, and is filtered through finer openings.

The slurry S filtered by the intermediate slurry filtering section 23B reaches the downstream slurry filtering section 23C. The downstream slurry filtering section 23C is composed of a pair of fine mesh members 26. Thereby, the slurry S is filtered even more finely.

Therefore, as the slurry S sequentially passes through the first slurry fluidization section 20, the upstream slurry filtering section 23A, the intermediate slurry filtering section 23B, and the downstream slurry filtering section 23C, the slurry S is filtered into finer particles.

Next, the slurry S reaches the second slurry fluidization section 40. In the second slurry fluidization section 40, a slurry mixer 42 is fitted into a nipple 41 that constitutes a flow path through which the slurry S is pumped. Further, a plurality of inclined grooves 48 are formed on the outer peripheral surface of the slurry mixer 42. Therefore, the slurry S passes through the inclined groove 48 and is conveyed through the slurry mixer 42 from the upstream side to the downstream side.

FIG. 10 is a conceptual diagram showing the flow of the slurry S in the inclined groove 48, and is an enlarged view of the upstream side of the inclined groove 48 viewed from the side. As shown in FIG. 10, the inclined groove 48 is inclined with respect to the pumping direction F. Therefore, as shown by the arrow G1 in FIG. 10, the slurry S is guided in the inclined groove 48 in a direction inclined with respect to the pumping direction F. As a result, a shearing force is generated in the slurry S, so that the fluidity of the slurry S increases.

FIG. 11 is a sectional view taken along the line XI-XI in FIG. 3, and shows the space X on the outer peripheral side of the narrow diameter portion 47. As shown in FIG. 11, the slurry S that has passed through the inclined groove 48 reaches a space X defined between the narrow diameter portion 47 and the inner wall surface of the nipple 41. Since the slurry S reaches the space X along the extending direction of the inclined grooves 48, it flows around the outer periphery of the narrow diameter portion 47 in the inclined direction of the inclined grooves 48, as shown by arrow G2 in FIG. It's easy to do. As a result, the slurry S whose fluidity has increased after passing through the inclined grooves 48 is stirred in the space X, and its fluidity is maintained or further increased.

The slurry S stirred in the space X is guided to the inclined groove 48 on the downstream side, and its fluidity is further increased. In the present embodiment, the second slurry fluidization section 40 has a plurality of inclined grooves 49 to 51 formed in each of the three large diameter parts 44 to 46, and two grooves 49 to 51 between the three large diameter parts 44 to 46. A narrow diameter portion 47 is provided.

Therefore, in the second slurry fluidization section 40, the slurry S is promoted to be fluidized in the inclined grooves 49 to 51 of the three large diameter parts 44 to 46, and is stirred at the outer periphery of the two small diameter parts 47. fluidity is maintained or even increased. In other words, shearing force is applied to the slurry S by combining the application of shearing force by the inclined grooves 48 in the large diameter part 43 and the application of shearing force by stirring in the space X of the outer peripheral part of the small diameter part 47. Granted continuously.

In addition, as shown in FIG. 12, which has a cross section similar to FIG. can be made into Specifically, in the slurry S that is pumped through the slurry pipe 7, a velocity gradient occurs in the cross section of the inclined groove 48 such that the flow velocity decreases toward the groove wall surface. This velocity gradient generates a shearing force in the slurry S, increasing its fluidity. Since the slanted grooves 48 have a small cross-sectional area, the velocity gradient tends to occur over substantially the entire cross-section of the flow path (shown with cross hatching), making it easier to fluidize the slurry S efficiently.

On the other hand, as shown in FIG. 13, in the cross section of the slurry pipe 7 where the slurry mixer 42 is not provided, the portion where the velocity gradient is large is the inner wall surface of the slurry pipe 7, as shown with cross hatching. , it is difficult to generate shearing force in the slurry S over the entire cross section of the channel, making it difficult to efficiently fluidize the slurry S.

The slurry S that has passed through the second slurry fluidization section 40 reaches the second three-way valve 8b. Since the fluidity of the slurry S tends to decrease over time, when it is confirmed that the pressure of the slurry S measured by the pressure sensor 9 is stable within a predetermined pressure range, the second three-way valve 8b Switched to the valve position, the slurry S reaches the slurry spraying device 5 via the fourth slurry pipe 7d.

Since the slurry S has sufficiently increased fluidity by the slurry fluidization device 4, it is atomized substantially uniformly by the slurry spraying device 5 and thermally sprayed by the slurry thermal spraying device 6 on the downstream side.

According to the thermal spraying system 1 described above, the following effects are achieved.

(1) Since the slurry mixer 42 is fitted into the nipple 41, the slurry S is pumped from the upstream side to the downstream side of the slurry mixer 42 through the inclined groove 48 formed on the outer circumference thereof. Since the inclined groove 48 is inclined with respect to the axial direction of the slurry pipe 7, that is, with respect to the pumping direction F, the slurry S is guided in the inclined groove 48 in a direction inclined with respect to the pumping direction F. As a result, shearing force is generated in the slurry S that is pumped into the inclined grooves 48, making it easier to fluidize the slurry S.

Further, in the slurry S that is pumped through the slurry pipe 7, a portion of the slurry S that is pumped along the inner wall surface of the pipe tends to be decelerated, and a velocity gradient occurs near the inner wall surface. Due to the velocity gradient, a shearing force is generated in the slurry S near the inner wall surface of the pipe, and the slurry S is likely to be fluidized. Here, since the inclined groove 48 has a smaller flow path cross section than the slurry pipe 7, the velocity gradient described above is likely to occur over the entire cross section of the flow path, and the entire slurry S in the inclined groove 48 is efficiently fluidized. Easy to do.

Therefore, by force-feeding the slurry S into the inclined groove 48, a shearing force is generated in the slurry S that is force-fed through the slurry pipe 7, and its fluidity can be easily increased or maintained. Furthermore, the pressure of the slurry S that is pumped through the slurry pipe 7 is used to guide the slurry S to the inclined groove 48, and there is no need to provide a screw or the like for stirring the slurry S in the slurry pipe 7. It is energy saving as it does not require any power. Further, since the slurry fluidization device 4 can be configured simply and compactly, it can be easily installed in the slurry piping 7 and has a high degree of freedom in arrangement.

(2) The plurality of inclined grooves 48 suppresses an excessive pressure increase caused by force feeding the slurry S to the inclined groove 48 whose flow path has a smaller cross-sectional area than the slurry piping 7 while increasing the flow rate. , can be pumped. This makes it easier to stably fluidize the slurry S.

(3) Generally, as the inclined grooves 48 become longer, the direction in which the slurry S is pumped in the inclined grooves 48 tends to follow the extending direction of the inclined grooves 48, and the shearing force generated in the slurry S becomes weaker. Since the inclined grooves 48 are formed in the large diameter portions 43 that are provided intermittently, it is possible to prevent the inclined grooves 48 from becoming excessively long. It is easy to end the guidance by 48. Therefore, high shearing force is intermittently generated in the slurry S by the inclined grooves 48 that are intermittently formed in the pumping direction F.

Further, the slurry S fluidized by each of the plurality of inclined grooves 48 flows into the space X defined between the narrow diameter portion 47 and the inner wall surface of the slurry pipe 7 and is mixed and stirred, so that the slurry S As a result, it is easy to maintain and increase the fluidity of the slurry S generated by the inclined grooves 48 in the narrow diameter portion 47.

Therefore, by the inclined grooves 48 and the narrow diameter portions 47 in the plurality of large diameter portions 43, it is easy to maintain a high shear force generated in the slurry S pumped from the upstream side to the downstream side of the slurry mixer 42, and the slurry S is further Easy to effectively fluidize.

(4) Since the pair of inclined grooves 48 adjacent to each other in the pumping direction F are inclined in opposite directions, the flow direction of the slurry S is determined when switching from the upstream inclined groove 48 to the downstream inclined groove 48. tends to change significantly, and the shearing force generated in the slurry S increases. This further increases the fluidity of the slurry S.

(5) In the pumping direction F, the number of inclined grooves 48 formed in the large diameter portion 43 located on the upstream side is equal to or less than the number of inclined grooves 48 formed in the large diameter portion 43 located on the downstream side. , as the slurry S is pumped from the upstream side to the downstream side, the amount of fluidized increases. This gradually reduces the viscosity of the slurry S, making it easier to fluidize the slurry S efficiently.

(6) Since the outer circumferential portion of the large diameter portion 43 is configured with a male screw, the area where the inner wall surface of the nipple 41 and the outer surface of the slurry mixer 42 fitted inside the nipple 41 are fitted is minimized. The slurry mixer 42 is prevented from sticking to the nipple 41. Therefore, the workability of attaching and detaching the slurry mixer 42 to the nipple 41 is improved. In particular, the above effect is suitably exhibited when fluidizing a slurry S containing fine particles, which tends to get caught and seize between the slurry mixer 42 and the nipple 41.

(7) Since the slurry S is filtered by the slurry filtering section 23, it is suppressed that the slurry S becomes lumpy and is forced to be fed. This makes it easier to further promote the flow of the slurry S.

(8) In the slurry filtering section 23, the openings of the mesh member become finer toward the downstream side in the pumping direction F, so that the slurry S is filtered gradually finer as it is pumped from the upstream side to the downstream side. This facilitates further promotion of fluidization of the slurry S.

(9) Since the intermediate slurry filtering section 23B is composed of a pair of coarse mesh members 25 stacked in different phases, a flow path extends from the opening of one coarse mesh member 25 to the opening of the other coarse mesh member 25. is configured so that it can be twisted. As a result, the slurry S is filtered while being twisted by the intermediate slurry filtering section 23B, which generates shearing force and increases fluidity.

Further, by constructing the intermediate slurry filtering section 23B from a pair of coarse mesh members 25 stacked in different phases, the openings of the intermediate slurry filtering section 23B become finer, so that the flow of the slurry S is easily promoted.

(10) In the upstream slurry filtration section 23A, there are two spaces for the relatively high viscosity slurry S that has passed through the coarse mesh member 25 on the upstream side to flow into the coarse mesh member 25 located on the downstream side. Since the slurry S filtered by the upstream coarse mesh member 25 is kept long by the spacer 27, it is easy to sufficiently mix and stir the slurry S filtered by the upstream coarse mesh member 25 before reaching the downstream coarse mesh member 25. This further promotes the fluidity of the slurry S.

(11) The length L1 of the inclined groove 48 is 102% or more of the length L0 of the large diameter portion 43, and the total length L1 of the plurality of inclined grooves 48 formed in one large diameter portion 43 is The length is 310% or more of the length L0 of the large diameter portion 43. As a result, a predetermined length of the inclined groove 48 is ensured, so that a sufficient shearing force is applied to the slurry S.

(12) Since the inclination angle A of the inclined groove 48 is set to 5 degrees or more and 85 degrees or less, sufficient shearing force is applied to the slurry S. When the inclination angle A is less than 5 degrees, the shearing force tends to be insufficient along the pumping direction. When the inclination angle A exceeds 85 degrees, it is difficult to secure a gap between adjacent inclined grooves 48.

(13) Since the groove width W of the inclined groove 48 is set to be 1 mm or more and less than the radius R of the large diameter portion 43, a velocity gradient is applied to the slurry S to be pumped across the cross section of the inclined groove 48. It is easy to generate a shearing force in the slurry S. If the groove width W is less than 1 mm, the flow path in the inclined groove 48 becomes excessively small, so that the pressure of the slurry S to be pumped tends to increase excessively. If the groove width W is larger than the radius R of the large diameter portion 43, the inclined groove 48 will become too large, making it difficult to cause a velocity gradient in the slurry S being pumped across the cross section of the inclined groove 48.

(14) Since the depth H of the inclined groove 48 is set to 1 mm or more and 90% or less of the radius R of the large diameter portion 43, a velocity gradient is created in the slurry S being pumped across the cross section of the inclined groove 48. It is easy to generate a shearing force in the slurry S. If the depth H is less than 1 mm, the flow path in the inclined groove 48 becomes excessively small, so that the pressure of the slurry S to be pumped tends to increase excessively. If the depth H is greater than 90% of the radius R of the large diameter portion 43, the inclined grooves 48 will become too large, making it difficult to create a velocity gradient in the slurry S being pumped across the cross section of the inclined grooves 48.

In the embodiment described above, the first slurry fluidization section 20 is composed of three slurry filtering sections 23 whose openings become smaller in order, but the present invention is not limited to this. That is, the slurry filtering section 23 may be composed of one or more.

Further, in the embodiment described above, the slurry mixer 42 in the second slurry fluidization section 40 is configured to have three large diameter parts 43 and two small diameter parts 47, but the present invention is not limited to this. That is, the slurry mixer 42 may be configured with only one large diameter portion 43, or may be configured to have two or more large diameter portions 43 and a narrow diameter portion 47 provided between them. Good too.

Further, in the above embodiment, the slurry fluidization device 4 is configured to include the first slurry fluidization section 20 and the second slurry fluidization section 40, but the present invention is not limited to this. That is, the slurry fluidization device 4 may be configured to include at least the second slurry fluidization section 40 and does not necessarily need to include the first slurry fluidization section 20.

Further, in the above embodiment, a slurry containing fine particles is used as an example of the thermal spray material, but the fine particles may include nanoparticles. As the fine particle-containing slurry, for example, a nanoparticle-containing slurry in which only nanoparticles are dispersed in an organic solvent may be employed. The effects of the present invention are more suitably exhibited in nanoparticle-containing slurries that are difficult to transport within piping. The organic solvent constituting the fine particle-containing slurry is not limited to an acrylic solvent, but may also be a urethane solvent or an epoxy solvent. Further, as the fine particles, not only aluminum oxide but also zirconium oxide, silicon, silicon carbide, tungsten carbide, or a mixture thereof can be used.

Note that the present invention is not limited to the configuration described in the above embodiments, and various changes are possible.

An evaluation test was conducted on the fluidity of slurry S using the slurry piping of Comparative Example 1 shown in Table 1 below, and the slurry fluidization devices of Comparative Example 2 and Examples 1 and 2. Slurry S used in this evaluation was prepared by mixing aluminum oxide fine particles having a median diameter D50 of 500 nm with a liquid acrylic resin as an organic solvent at a volume ratio of 50%. That is, the volume ratio of the slurry S is 50% fine particles and 50% liquid resin. This slurry S has thixotropic properties.

As shown in Table 1, in Comparative Example 1, the slurry fluidization device 4 was not provided, and the slurry pipe 7 was simply configured. In Comparative Example 2, the slurry fluidization device 4 is provided with only the first slurry fluidization section 20 and is not provided with the second slurry fluidization section 40.

Example 1 is the slurry fluidization device 4 according to the example described above, that is, both the first and second slurry fluidization sections 20 and 40 are provided. Example 2 differs from Example 1 in that the slurry mixer 42 is changed to a slurry mixer 60 according to a modified example shown in FIG. 14. As shown in FIG. 14, the slurry mixer 60 includes two large-diameter parts 63, one small-diameter part 67 located between them, and inclined grooves 68 formed in each of the two large-diameter parts 63. ing.

In the fluidity evaluation, the slurry S was pumped from the slurry supply device 3 at a rate of 10 cc per minute and passed through the slurry piping 7 or the slurry fluidization device 4 according to Comparative Examples 1 and 2 and Examples 1 and 2, respectively. After that, when the slurry S was discharged horizontally, the thickness (diameter) of the slurry S dripping downward and the length until it stopped were measured. In the overall judgment, it was determined that the fluidity of the slurry S that dripped downward was improved as the thickness became thinner and as the length until it stopped was longer.

As shown in Table 1, Comparative Example 1 does not include both the first and second slurry fluidizing sections 20 and 40, so the slurry S is not fluidized and the discharged slurry S has a thickness of It is about 8mm long and drips down with repeated interruptions at about 15mm in length. The liquidity is insufficient and is rated "x".

Compared to Comparative Example 1, Comparative Example 2 is equipped with the first slurry fluidizing section 20, so the fluidity of the slurry S is slightly improved, and the discharged slurry S has a thickness of approximately 6 mm and a length of approximately 6 mm. It drips down repeatedly, cutting off at about 50mm. Although a little smoothness was observed compared to Comparative Example 1, the fluidity was still insufficient, resulting in a rating of "△".

Since Examples 1 and 2 both include the second slurry fluidization section 40, the fluidity of the slurry S is further improved compared to Comparative Examples 1 and 2. In Example 1, the discharged slurry S had a thickness of about 1.0 mm and dripped down for a predetermined length without interruption, and the fluidity was evaluated as "◎" without any problem.

On the other hand, in Example 2, the discharged slurry S drips down while repeating interruptions at approximately 1.5 mm in thickness and approximately 80 mm in length. Compared to Example 1, although the fluidity of slurry S is lower, it is generally at an acceptable level and is evaluated as "○". In Example 2, the number of large diameter portions 43 and small diameter portions 47 in the second slurry fluidization section 40 was smaller than in Example 1, so the fluidity was inferior to that in Example 1. Presumed.

Industrial availability

As explained above, the slurry fluidization device according to the present invention can improve the fluidity of the fine particle-containing slurry that is pumped into the pipe, and is therefore suitable for use in this type of technical field. there is a possibility.

1 Thermal spraying system 2 Slurry storage tank 3 Slurry supply device 4 Slurry fluidization device 5 Slurry spraying device 6 Slurry thermal spraying device 7 Slurry piping 9 Pressure sensor 20 First slurry fluidization section 23 Slurry filtering section 25 Coarse mesh member 26 Fine mesh member 40 Second slurry fluidization section 42 Slurry mixer 43 Large diameter section 47 Narrow diameter section 48 Inclined groove

Claims (5)

Piping through which slurry containing fine particles is pumped;
a rod-shaped member that is fitted inside the piping in the axial direction, and has an inclined groove extending in a direction inclined with respect to the axial direction on its outer circumference;
has
The inclined groove penetrates the rod-shaped member from one end to the other end in the axial direction,
The rod-shaped member is
a plurality of large diameter portions that are spaced apart in the axial direction and have the inclined grooves and male threads formed therein;
a narrow diameter portion that is located between the pair of large diameter portions adjacent to each other in the axial direction and is thinner than the large diameter portion;
It has
The piping has a cylindrical nipple into which the rod-shaped member is inserted, and a slurry outlet socket connected to an end of the nipple in the axial direction,
The slurry outlet socket is a cylindrical member having a hole penetrating in the pumping direction in which the fine particle-containing slurry is pumped. has a counterbore to which the end portion of is connected;
The large diameter portion has an outer peripheral portion formed by the male thread extending in a direction inclined to one side in the left-right direction toward the downstream side in the pumping direction of the fine particle-containing slurry,
The rod-shaped member is fixed to the hole of the slurry outlet socket in a cantilevered state by screwing the male screw into the mouth of the hole of the slurry outlet socket ,
The piping is further provided with a slurry filtering section,
The slurry filtering section is composed of a net-like mesh member,
The slurry filtering section is provided in plurality,
The plurality of slurry filtering units are slurry fluidizing devices, in which the openings of the mesh member become finer toward the downstream side in the pumping direction of the fine particle-containing slurry. The pair of inclined grooves formed in each of the pair of large diameter portions adjacent to each other in the axial direction are inclined in directions opposite to each other with respect to the axial direction.
The slurry fluidization device according to claim 1 . Among the plurality of large diameter parts, the number of inclined grooves formed in the large diameter part located on the upstream side in the axial direction is equal to the number of inclined grooves formed in the large diameter part located on the downstream side. The number of formations is less than or equal to
The slurry fluidization device according to claim 1 or 2 . The slurry filtering section is configured by a plurality of the mesh members stacked in mutually different phases.
Slurry fluidization device according to any one of claims 1 to 3 . The slurry strainer is provided in three or more at intervals in the axial direction,
The distance between the slurry filtering parts is longer on the upstream side than on the downstream side.
Slurry fluidization device according to any one of claims 1 to 4 .

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