JP7612466B2 - Powder Discharge Mechanism - Google Patents

Description

The present invention relates to a powder ejection mechanism.

In metal pipes such as cast iron pipes used for water supply and sewerage, the inside of the metal pipe may be painted with epoxy resin from the viewpoint of corrosion resistance and reducing the burden on the environment. When painting, an inexpensive filler such as silica sand may be included in the coating material to reduce the proportion of expensive epoxy resin. Patent Document 1 discloses a method for painting the inside of a metal pipe in which a constant supply of silica sand is supplied by a screw feeder in parallel with the spraying of epoxy resin onto the inner wall surface of the metal pipe, and the supplied silica sand is carried by compressed air and sprayed onto the inner wall surface of the metal pipe. According to the painting method of Patent Document 1, a coating film of a mixture of epoxy resin and silica sand can be formed inside the metal pipe.

JP 2020-131151 A

In Patent Document 1, silica sand supplied by a screw feeder is dropped into a horizontally extending compressed air flow path while still in a state of free fall vertically downward motion. In this case, resistance increases when the silica sand is placed on the compressed air, so the silica sand may not be sufficiently carried by the compressed air and accumulate vertically downward in the flow path, making it difficult to spray the silica sand onto the inner surface of the metal pipe. For this reason, there is a demand for a method that can effectively spray powder such as silica sand onto a target such as the inner surface of a metal pipe.

In view of these problems, the present invention aims to provide a powder ejection mechanism that can effectively spray powder onto an object.

The powder discharge mechanism according to one embodiment of the present invention is a powder discharge mechanism that discharges powder toward a target object using compressed gas, and includes a powder supply unit that supplies the powder at a predetermined supply amount, a powder transport unit that has a flow path for the compressed gas that extends vertically downward from the powder supply unit and crosses the vertical direction, and transports the powder in a transport direction along the flow path by the compressed gas flowing in the flow path, and a powder input unit that drops the powder from the powder supply unit to the powder transport unit, and the powder input unit has a powder input port provided on the powder supply unit side, a powder outlet provided on the powder transport unit side, and a powder contact portion provided between the input port and the outlet and against which the powder dropped into the powder input unit comes into contact, and the powder input from the input port is discharged from the discharge port so as to be input into the flow path after the powder contacts the powder contact portion, changing the direction of motion of the powder so as to increase at least the component of motion in the transport direction.

The powder inlet may include a tubular passageway connecting the inlet and the outlet, the angle between the central axis of the passageway on the powder transport section side and the transport direction being smaller than the angle between the central axis of the passageway on the powder supply section side and the transport direction, and the powder contact section may be formed by the inner surface of the passageway located on the powder transport section side of the passageway opposite the transport direction.

The passage may be spaced apart from the powder supply section.

The target object is the inner surface of a tube, the transport direction is a direction along the central axis of the tube, and the device further includes a powder discharge section connected to the powder transport section in the transport direction and discharging the powder toward the target object, and the powder discharge section may discharge the powder toward the inner surface in a direction intersecting the transport direction.

The powder ejection mechanism according to one embodiment of the present invention allows the powder to be effectively sprayed onto a target object.

1 is a schematic partial cross-sectional view showing a coating device in which a powder discharging mechanism according to an embodiment of the present invention is incorporated. FIG. 2 is a schematic side view showing a powder discharging mechanism according to an embodiment of the present invention. FIG. 2 is a schematic enlarged cross-sectional view showing a powder discharging mechanism according to an embodiment of the present invention.

The powder discharge mechanism according to one embodiment of the present invention will be described below with reference to the attached drawings. Note that the embodiment shown below is merely an example, and the powder discharge mechanism of the present invention is not limited to the following embodiment. Note that in this specification, "perpendicular to A" and similar expressions do not only refer to a direction completely perpendicular to A, but also refer to a direction that is approximately perpendicular to A. Also, in this specification, "parallel to B" and similar expressions do not only refer to a direction completely parallel to B, but also refer to a direction that is approximately parallel to B. Also, in this specification, "C-shape" and similar expressions do not only refer to a perfect C-shape, but also refer to a shape that visually resembles a C-shape (approximately a C-shape), such as a shape with chamfered corners of a C-shape.

[Powder Discharge Mechanism According to an Embodiment of the Invention]
FIG. 1 shows a powder discharge mechanism 1 according to an embodiment of the present invention. As shown in FIG. 1, the powder discharge mechanism 1 discharges powder S1 toward a target T using compressed gas G1. Here, in this specification, "compression" refers to contracting the volume of gas by pressurizing the gas using a compressor or the like. Also, in this specification, "compressed gas" refers to gas whose volume has been contracted by pressurization. When the compressed gas G1 is released from the compressed state, it generates an airflow. The powder discharge mechanism 1 discharges powder S1 toward a target T using this airflow.

The compressed gas G1 used in the powder discharge mechanism 1 is not particularly limited, but in this embodiment, it is compressed air. However, the gas to be compressed is not particularly limited, and may be other gases such as a rare gas.

In this embodiment, the powder S1 discharged by the powder discharge mechanism 1 is a powder with a relatively heavy specific gravity (for example, specific gravity: 2.0), specifically, silica sand (for example, specific gravity: 2.5). Even if the powder S1 has a relatively heavy specific gravity like this, the powder discharge mechanism 1 according to this embodiment can spray the powder S1 well onto the target T, as described later. Here, in this specification, "silica sand" is a powder whose main component is quartz (for example, the quartz content is 80 wt% or more), and includes silica sand whose surface is coated with any material. Also, in this specification, "powder" is, for example, a powder having an average particle size of 5 μm to 1000 μm, preferably a powder having an average particle size of 10 μm to 500 μm, and more preferably a powder having an average particle size of 50 μm to 200 μm. When the powder S1 is silica sand, for example, No. 7 silica sand or No. 8 silica sand can be used. The powder discharge mechanism 1 according to this embodiment may also be used to spray other powders, such as powdered epoxy resin with a relatively light specific gravity (for example, specific gravity: 1.5).

In this embodiment, the object T onto which the powder ejection mechanism 1 ejects the powder S1 is a tube having an internal space extending along the central axis X1, as shown in FIG. 1, and more specifically, the inner surface of the tube. The object T is, for example, a metal pipe such as a cast iron pipe used for water supply and sewerage. However, the object T may also be the outer wall of a metal pipe, or may be selected from the surface of any other object.

Although the form of use of the powder discharge mechanism 1 is not particularly limited, in this embodiment, as shown in FIG. 1, the powder discharge mechanism 1 is incorporated into a coating device A for coating an object T together with a paint discharge mechanism 2 that discharges paint S2 toward the object T. The coating device A can discharge silica sand as powder S1 by the powder discharge mechanism 1 while discharging powdered epoxy resin as paint S2 by the paint discharge mechanism 2. In this embodiment, the powder discharge mechanism 1 and the paint discharge mechanism 2 each include a powder pipe 1a and a paint pipe 2a that extend into the internal space of the object T along the central axis X1 of the object T (specifically, the tube). In this embodiment, the powder discharge mechanism 1 discharges powder S1 toward the target T (specifically, the inner surface of the pipe) from a powder discharge section 14 (e.g., a spray nozzle) provided at the end of the powder pipe 1a, and the paint discharge mechanism 2 discharges paint S2 toward the target T (specifically, the inner surface of the pipe) from a paint discharge section 24 (e.g., a spray nozzle) provided at the end of the paint pipe 2a.

In this embodiment, as shown in FIG. 1, the coating device A is equipped with a movable cart C (carrier), and at least a portion of the powder discharge mechanism 1 and/or the paint discharge mechanism 2 is mounted on the cart C, so that it can move together with the cart C (specifically, can move horizontally).

2, the powder discharge mechanism 1 includes a powder supply unit 11 that supplies a predetermined amount of powder S1, a powder conveying unit 13 that conveys the powder S1 by the compressed gas G1 in a conveying direction D21 along the flow path 131 (see FIG. 3) of the compressed gas G1, and a powder input unit 12 that drops the powder S1 from the powder supply unit 11 into the powder conveying unit 13. As described above, the powder discharge mechanism 1 can further include a powder discharge unit 14 that discharges the powder S1 toward the target T. For example, of the powder discharge mechanism 1, a part of the powder supply unit 11 (a mixing tank 112 and a powder supply device 113 described later), the powder input unit 12, and the powder conveying unit 13 are mounted on the aforementioned dolly C.

As shown in FIG. 2, the powder supply unit 11 stores the powder S1 and supplies the stored powder S1 to the powder conveying unit 13 via the powder input unit 12 at a predetermined supply amount. The form of the powder supply unit 11 is not particularly limited as long as it can supply the powder S1 to the powder conveying unit 13 at a predetermined supply amount. In this embodiment, the powder supply unit 11 supplies the powder S1 in a uniform state at a predetermined supply amount by using compressed gas G1. Specifically, the powder supply unit 11 includes a main tank 111 that stores the powder S1, a mixing tank 112 that mixes the powder S1 uniformly, and a powder supply device 113 that supplies the powder S1 at a predetermined supply amount. However, the powder supply unit 11 may have other structures, such as being composed only of the powder supply device 113.

The main tank 111 stores powder S1 and supplies the stored powder S1 to the mixing tank 112. In this embodiment, as shown in FIG. 2, the internal space of the main tank 111 is connected to the internal space of the mixing tank 112 in an openable and closable manner by a known on-off valve 1m. By providing the on-off valve 1m, it becomes easy to adjust the amount of powder S1 supplied to the mixing tank 112. The capacity of the main tank 111 is not particularly limited, but when the powder S1 is silica sand, for example, the main tank 111 can be selected to have a capacity capable of storing 1 ton of silica sand.

When supplying the powder S1 to the powder supply device 113, the mixing tank 112 mixes the powder S1 so that the components and particle size of the powder S1 are uniform. By making the powder S1 uniform, the powder discharge mechanism 1 can discharge the powder S1 without uneven discharge. In this embodiment, as shown in FIG. 2, the mixing tank 112 is provided with a separator 112c that separates the internal space into a gas chamber 112a vertically below D11 and a stirring chamber 112b vertically above D12. For example, the separator 112c is made of a porous material and is configured to allow gas to pass through while not allowing the powder S1 to pass through. In FIG. 2, the gas chamber 112a is connected to a compressed gas supply source (not shown, in this embodiment, the same compressed gas supply source as the compressed gas G1 described later) such as a known compressor that supplies compressed gas G2 (for example, compressed air) by a pipe 11a, and the compressed gas G2 supplied to the gas chamber 112a permeates the separator 112c and stirs the powder S1 supplied to the stirring chamber 112b, thereby uniformly mixing the powder S1. In this embodiment, the stirring chamber 112b is connected to the internal space of the powder supply device 113 by a known on-off valve 1n so as to be openable and closable. By providing the on-off valve 1n, it becomes easy to adjust the supply amount of the powder S1 to the powder supply device 113. The capacity of the mixing tank 112 is not particularly limited, but in this embodiment, in order to reduce the load of mixing the powder S1, it is set to a capacity smaller than the capacity of the main tank 111. If the powder S1 is silica sand, for example, the mixing tank 112 can be selected to have a capacity capable of storing 30 kg of silica sand.

3, the powder supply device 113 supplies the powder S1 from the supply port 113a to the powder input section 12 at a predetermined supply rate. In this embodiment, the powder supply device 113 is a screw feeder that has a screw extending along the rotation axis X2 in the internal space and supplies the powder S1 to one side of the rotation axis X2 on which the supply port 113a is provided by rotating the screw around the rotation axis X2. By using the screw feeder, the supply amount of the powder S1 to the powder input section 12 can be kept constant and the supply amount can be finely adjusted. However, the form of the powder supply device 113 is not particularly limited as long as the powder S1 can be supplied at a predetermined supply rate. In this embodiment, the direction in which the rotation axis X2 extends is horizontal. However, as long as the powder S1 can be supplied to the powder input section 12 at a predetermined supply rate, the direction in which the rotation axis X2 extends is not particularly limited.

As shown in FIG. 3, the powder feed section 12 connects the powder supply section 11 and the powder conveying section 13 so that the powder S1 can be dropped from the powder supply section 11 to the powder conveying section 13. The powder feed section 12 has an inlet 12a for the powder S1 provided on the powder supply section 11 side, an outlet 12b for the powder S1 provided on the powder conveying section 13 side, and a powder abutment section 12c provided between the inlet 12a and the outlet 12b and against which the powder S1 dropped into the powder feed section 12 abuts. The powder S1 fed from the inlet 12a abuts against the powder abutment section 12c, thereby changing the direction of motion so as to increase at least the motion component in the conveying direction D21 of the flow path 131, and then being discharged from the outlet 12b, so as to be fed into the flow path 131 of the powder conveying section 13. The form of the powder input section 12 is not particularly limited as long as it has a powder contact section 12c that increases the motion component of the powder S1 in the transport direction D21 of the flow path 131. In this embodiment, the powder input section 12 has a passage 121 through which the dropped powder S1 passes. However, the powder input section 12 may be configured in other forms, such as being composed only of a plate-shaped member that the dropped powder S1 contacts to increase the motion component in the transport direction D21 of the flow path 131.

As shown in FIG. 3, the passage 121 guides the powder S1 dropped from the inlet 12a to the outlet 12b. In FIG. 3, the passage 121 is a tubular passage connecting the inlet 12a and the outlet 12b, and the powder contact portion 12c is formed by the inner surface of the passage 121 located on the opposite side of the conveying direction D21 of the flow path 131. Here, since compressed gas G1 flows through the flow path 131, the flow path 131 becomes negative pressure, and a suction force acts on the powder supply portion 11 and the passage 121. Therefore, if the inlet 12a and the supply port 113a are connected, there is a risk that the powder S1 in the powder supply portion 11 will be excessively sucked. Therefore, in this embodiment, the powder inlet 12 is provided at a distance from the powder supply portion 11 (specifically, the powder supplier 113). In other words, the inlet 12a of the passage 121 is provided away from the supply port 113a of the powder supply device 113. In this way, the portion between the passage 121 and the powder supply unit 11 is not connected and is open to the atmosphere, so that excessive suction of the powder S1 from the powder supply unit 11 into the flow path 131, which is under negative pressure, is suppressed. In this case, air is also sucked in together with the powder S1, so that the capacity of the powder conveying unit 13 can be fully demonstrated. In this embodiment, the inlet 12a is provided to include the supply port 113a when viewed from the vertical direction D1, for example, so as not to interfere with the introduction of the powder S1 from the supply port 113a. However, the passage 121 may be connected to the powder supply unit 11 (specifically, the powder supply device 113) so that the inlet 12a of the passage 121 coincides with the supply port 113a of the powder supply unit 11. In this embodiment, the passage 121 is connected to the flow path 131 of the powder conveying unit 13 to ensure that the powder S1 is dropped into the flow path 131 of the compressed gas G1. However, the passage 121 may be provided away from the flow path 131 of the powder conveying unit 13. In this case, the discharge port 12b is provided to include the inlet 13b when viewed from the vertical direction D1, for example, so as not to prevent the introduction of the powder S1 from the inlet 13b.

In this embodiment, as shown in FIG. 3, the passage 121 is provided with a powder contact portion 12c so that the normal N to the inner surface of the passage 121 forms an acute angle α with respect to the vertical downward direction D11 into which the powder S1 is dropped. In this case, the powder S1 contacts the powder contact portion 12c, which can easily increase the motion component in the conveying direction D21 of the flow path 131. In FIG. 3, the passage 121 is bent between the powder supply unit 11 side and the powder conveying unit 13 side. By bending the passage 121, the powder S1 that contacts the inner surface of the passage 121 is less likely to bounce back to the vertical upward direction D12, thereby improving the efficiency of dropping the powder S1 into the passage 121. Specifically, the passage 121 is bent so that the discharge port 12b is located downstream of the inlet 12a in the conveying direction D21 of the flow path 131. 3, the passage 121 is bent so that the angle β1 between the central axis Y1 of the passage 121 on the powder conveying section 13 side and the conveying direction D21 of the flow path 131 is smaller than the angle β2 between the central axis Y2 of the passage 121 on the powder supply section 11 side and the conveying direction D21 of the flow path 131, and the powder abutment portion 12c is formed by the inner surface of the passage 121 located on the opposite side of the conveying direction D21 of the flow path 131 on the powder conveying section 13 side of the passage 121. In this case, the passage 121 on the powder conveying section 13 side, in which the angle β1 with the conveying direction D21 of the flow path 131 is smaller, is connected to the flow path 131 of the powder conveying section 13, so that turbulence of gas is less likely to occur near the confluence of the passage 121 and the flow path 131. The angle β1 between the central axis Y1 of the passage 121 on the powder conveying section 13 side and the conveying direction D21 of the flow path 131 can be set preferably within the range of 30 degrees to 60 degrees, more preferably within the range of 35 degrees to 55 degrees, and even more preferably within the range of 40 degrees to 50 degrees. The angle β2 between the central axis Y2 of the passage 121 on the powder supplying section 11 side and the conveying direction D21 of the flow path 131 can be set preferably within the range of 60 degrees to 90 degrees, more preferably within the range of 70 degrees to 90 degrees, and even more preferably within the range of 80 degrees to 90 degrees.

In this embodiment, the discharge port 12b is provided so as not to overlap with the inlet 12a when viewed from the vertical direction D1. In this case, the powder S1 dropped from the inlet 12a is prevented from being discharged from the discharge port 12b without contacting the powder contact portion 12c. In this embodiment, the discharge port 12b is provided so as to have a size larger than the inlet 12a. In this case, when the powder S1 is discharged from the discharge port 12b, the powder S1 does not become high density near the discharge port 12b, so the powder S1 can be easily dropped into the powder conveying portion 13.

As shown in FIG. 3, the powder conveying section 13 conveys the powder S1 supplied from the inlet 13b by the compressed gas G1. The powder conveying section 13 has a flow path 131 for the compressed gas G1 that extends vertically downward D11 from the powder supply section 11 so as to intersect with the vertical direction D1. The direction D2 in which the flow path 131 extends (in other words, the conveying direction D21 of the flow path 131) can be changed as appropriate depending on the usage mode of the powder discharge mechanism 1, but in this embodiment, it is a horizontal direction. The shape of the flow path 131 is not particularly limited as long as the powder S1 can be conveyed by the compressed gas G1. In this embodiment, the flow path 131 is constituted by the internal space of the powder conveying section 13 having a cylindrical shape. However, the flow path 131 may be constituted by the internal space of the powder conveying section 13 having a square tube shape, and may be narrowed toward the conveying direction D21 of the flow path 131, or may be widened toward the conveying direction D21 of the flow path 131. The powder conveying unit 13 conveys the powder S1 in a conveying direction D21 of the flow path 131 along the flow path 131 by compressed gas G1 flowing in the flow path 131. In FIG. 3, the flow path 131 is connected to a compressed gas supply source such as a known compressor (not shown; in this embodiment, the compressed gas supply source is the same as the compressed gas G2 (see FIG. 2) described above) by a pipe 13a.

As shown in FIG. 1, the powder discharge unit 14 discharges the powder S1 conveyed from the powder conveying unit 13 (see FIG. 2 and FIG. 3) toward the target T. Specifically, as shown in FIG. 2, the powder discharge unit 14 is connected to the flow path 131 of the powder conveying unit 13 on the conveying direction D21 side by the powder pipe 1a, and discharges the powder S1 conveyed from the powder conveying unit 13 toward the target T (see FIG. 1) by the compressed gas G1. The discharge direction of the powder S1 can be changed appropriately depending on the usage mode of the powder discharge mechanism 1, but in this embodiment, the powder discharge unit 14 discharges the powder S1 toward the inner surface of the tube, which is the target T, in a direction intersecting the conveying direction D21 of the flow path 131 (more specifically, a direction perpendicular to the central axis X1 of the tube, which is the target T (diameter direction of the tube)). In this case, the discharge direction of the powder S1 is different from the conveying direction D21 of the flow path 131, so there is a large pressure loss in the compressed gas G1. Even in such a case, in this embodiment, by increasing the motion component of the powder S1 in the conveying direction D21 of the flow path 131, the powder S1 can easily ride on the compressed gas G1, so that the powder S1 can be sprayed well onto the target T.

As described above, in this embodiment, the powder discharge unit 14 discharges the powder S1 onto the target T in parallel with the discharge of the paint S2 onto the target T by the paint discharge unit 24, as shown in FIG. 1. Specifically, the powder discharge unit 14 and the paint discharge unit 24 discharge the powder S1 and the paint S2, respectively, in a direction perpendicular to the central axis X1 of the tube, which is the target T (in the radial direction of the tube). In FIG. 1, the powder discharge unit 14 is connected to the powder pipe 1a so as to be disposed on the opposite side (right side of the paper in FIG. 1) to the moving direction of the cart C (in this embodiment, one direction (horizontal direction) along the central axis X1, the left side of the paper in FIG. 1) relative to the paint discharge unit 24, so that the paint S2 is discharged onto the target T (specifically, the inner surface of the tube) before the powder S1. In this way, when the powder S1 and the paint S2 are discharged while the cart C is moving, the paint S2 is discharged onto the object T (specifically, the inner surface of the tube) before the powder S1. In this case, the powder S1 mixes with the paint S2 before the paint S2 hardens, so that the powder S1 is more likely to adhere to the coating. In this embodiment, the object T (specifically, the tube) is placed on a rotating body R that rotates around the central axis X1. When the object T is a tube and the inner surface of the tube is to be painted, the powder discharge unit 14 and the paint discharge unit 24 are inserted into the internal space of the object T, and the cart C is moved along the central axis X1 while the object T is rotated around the central axis X1 by the rotating body R. In this way, the powder S1 and the paint S2 can be discharged onto the entire inner surface of the tube, which is the object T.

[Behavior of powder in a powder discharging mechanism according to an embodiment of the present invention]
Next, a description will be given of the behavior of the powder S1 in the above-described powder discharging mechanism 1. Note that the embodiment described below is merely an example, and the behavior of the powder in the powder discharging mechanism of the present invention is not limited to the embodiment described below.

In this embodiment, as shown in FIG. 2, first, the powder S1 is supplied to the powder supply section 11. Specifically, the powder S1 is stored in the main tank 111, and is supplied to the mixing tank 112 by opening the on-off valve 1m. In this embodiment, when the powder S1 is supplied to the mixing tank 112, the powder S1 is stirred in the stirring chamber 112b by the compressed gas G2 blown vertically upward D12 from the gas chamber 112a through the separator 112c, so that the components and particle size are homogenized. In this embodiment, the homogenized powder S1 is supplied to the powder supply device 113 by opening the on-off valve 1n, and then, as shown in FIG. 3, the powder supply device 113 drops a predetermined supply amount from the supply port 113a into the powder input section 12. In this embodiment, the powder input section 12 and the powder supply section 11 (specifically, the powder supply device 113) are disposed at a distance from each other, so the section between the passage 121 and the powder supply section 11 is not connected and is open to the atmosphere. This prevents excessive suction of the powder S1 from the powder supply section 11 into the flow path 131, which is in a negative pressure state. In this case, air is also sucked in along with the powder S1, so the powder transport section 13 can fully utilize its capabilities.

In this embodiment, as shown in FIG. 3, when powder S1 (see solid arrow in FIG. 3) is dropped into the powder input section 12 from the inlet 12a, it falls vertically downward D11 due to gravity and abuts against the powder abutment section 12c formed by the inner surface of the passage 121 located on the opposite side of the conveying direction D21 of the flow path 131. This abutment of the powder S1 against the powder abutment section 12c can increase the motion component of the powder S1 in the conveying direction D21 of the flow path 131. At that time, in this embodiment, the discharge port 12b is arranged so as not to overlap with the inlet 12a when viewed from the vertical direction D1, so that the powder S1 dropped from the inlet 12a is prevented from being discharged from the discharge port 12b without abutting against the powder abutment section 12c (in other words, without changing the direction of motion).

Some of the powder S1 may bounce vertically upward D12 due to contact with the inner surface of the passage 121. However, in this embodiment, since the passage 121 is curved, the direction of the rebound of the powder S1 is limited by the curved inner surface of the passage 121, making it difficult for the powder S1 to bounce vertically upward D12. In this case, for example, the powder S1 is prevented from escaping between the inlet 12a of the passage 121 and the supply inlet 113a of the powder supply unit 11 (specifically, the powder supply device 113) or from bouncing back to the powder supply unit 11 (specifically, the powder supply device 113), improving the efficiency of dropping the powder S1 into the passage 121.

In this embodiment, as shown in FIG. 3, the powder S1 (see the solid arrow in FIG. 3) is dropped from the discharge port 12b into the powder conveying section 13 in a state where the motion component in the same conveying direction D21 as the compressed gas G1 flowing through the flow path 131 of the powder conveying section 13 is increased by contacting the powder contact section 12c. Here, in this embodiment, the discharge port 12b is provided to have a size larger than the input port 12a. In this case, when the powder S1 is discharged from the discharge port 12b, the powder S1 does not become in a high-density state near the discharge port 12b, so the discharge performance of the discharge port 12b is improved. Therefore, in this embodiment, the powder S1 can be easily input into the powder conveying section 13 (specifically, the flow path 131 of the compressed gas G1).

3, powder S1 (see solid arrow in FIG. 3) is dropped into the powder conveying section 13 and introduced into the flow path 131 of compressed gas G1. Here, in this embodiment, the angle β1 between the central axis Y1 on the powder conveying section 13 side of the passage 121 and the conveying direction D21 of the flow path 131 is smaller than the angle β2 between the central axis Y2 on the powder supply section 11 side of the passage 121 and the conveying direction D21, and the powder abutment portion 12c is formed by the inner surface of the passage 121 located on the powder conveying section 13 side of the passage 121, opposite the conveying direction D21 of the flow path 131. In this case, by connecting the passage 121 on the powder conveying section 13 side, where the angle β1 of the passage 131 with the conveying direction D21 is reduced, the merging resistance between the gas from the passage 121 and the compressed gas G1 in the passage 131 at the junction of the passage 121 and the passage 131 is reduced, so that turbulence of the compressed gas G1 is less likely to occur at the junction of the passage 121 and the passage 131. Therefore, in this embodiment, the powder S1 is prevented from being difficult to convey due to turbulence generated in the passage 121 or the passage 131.

In this embodiment, as shown in FIG. 3, when powder S1 (see solid arrow in FIG. 3) is introduced into the flow path 131 of compressed gas G1, the component of motion in the same conveying direction D21 as compressed gas G1 flowing through flow path 131 increases, so powder S1 is more likely to ride on compressed gas G1. Therefore, in this embodiment, powder S1 is prevented from accumulating on the vertically downward D11 side within flow path 131, and is easily conveyed in conveying direction D21 by compressed gas G1.

In this embodiment, as shown in FIG. 1 (also see FIG. 3), the powder S1 is transported in the transport direction D21 by the compressed gas G1, and then discharged from the powder discharge section 14 to the inner surface of the tube, which is the target T, through the powder pipe 1a. In this embodiment, the powder S1 is discharged toward the target T in a direction intersecting the transport direction D21 (more specifically, in a direction perpendicular to the central axis X1 of the target T (diameter direction of the tube)). Therefore, the compressed gas G1 transporting the powder S1 has a large pressure loss due to the bending of the traveling direction. However, in this embodiment, even if the pressure loss of the compressed gas G1 is large, the movement component of the powder S1 in the transport direction D21 of the flow path 131 is increased, so that the resistance when the powder S1 is placed on the compressed gas G1 is reduced, and the powder S1 can be sprayed well onto the target T.

According to the powder discharge mechanism 1 according to the present embodiment configured as described above, the powder feed section 12 is provided between the feed port 12a and the discharge port 12b, and has a powder contact section 12c with which the powder S1 fed from the feed port 12a comes into contact. The powder S1 fed into the powder feed section 12 changes its motion direction so as to increase the motion component in the conveying direction D21 of the flow path 131 by contacting the powder contact section 12c, and is then discharged from the discharge port 12b and fed into the flow path 131. In this way, the powder S1 is more likely to ride on the compressed gas G1 before being fed into the flow path 131, as the motion component in the same conveying direction D21 as the compressed gas G1 flowing through the flow path 131 increases, and the powder S1 is prevented from accumulating vertically downward D11 due to gravity in the flow path 131. Therefore, the powder S1 can be sprayed well onto the target T.

In this embodiment, the angle β1 between the central axis Y1 of the passage 121 on the powder conveying section 13 side and the conveying direction D21 of the flow path 131 is smaller than the angle β2 between the central axis Y2 of the passage 121 on the powder supplying section 11 side and the conveying direction D21, and the powder abutment portion 12c is formed by the inner surface of the passage 121 located on the opposite side of the conveying direction D21 of the flow path 131 on the powder conveying section 13 side of the passage 121. When the powder S1 abuts against the inner surface of the passage 121, it may bounce back to the powder supplying section 11 side, but in this embodiment, the passage 121 is bent between the powder supplying section 11 side and the powder conveying section 13 side, so that the rebound of the powder S1 is suppressed. In addition, in this embodiment, the passage 121 on the powder conveying section 13 side, where the angle β1 between the passage 131 and the conveying direction D21 is reduced, is connected to the passage 131, so that turbulence of the compressed gas G1 is less likely to occur at the junction of the passage 121 and the passage 131. Therefore, in this embodiment, the powder S1 is prevented from being difficult to convey due to turbulence occurring in the passage 121 or the passage 131.

In this embodiment, the passage 121 is provided away from the powder supply unit 11. In this case, the portion between the passage 121 and the powder supply unit 11 is open to the atmosphere, so excessive suction of the powder S1 from the powder supply unit 11 to the flow path 131, which is in a negative pressure state, is suppressed. In this case, air is also sucked in along with the powder S1, so the capacity of the powder conveying unit 13 can be fully utilized.

In this embodiment, the powder discharge section 14 discharges the powder S1 toward the inner surface of the tube, which is the target T, in a direction intersecting the conveying direction D21 of the flow path 131. In this case, since the discharge direction of the powder S1 differs from the conveying direction D21 of the flow path 131, the compressed gas G1 conveying the powder S1 is bent in its traveling direction, resulting in a large pressure loss. However, in this embodiment, even in such a case, the powder S1 abuts against the powder abutment section 12c to increase the component of motion of the powder S1 in the conveying direction D21, thereby reducing the resistance of the powder S1 when it is placed on the compressed gas G1, and the powder S1 can be sprayed well onto the target T.

LIST OF SYMBOLS 1 Powder discharge mechanism 11 Powder supply section 111 Main tank 112 Mixing tank 112a Gas chamber 112b Stirring chamber 112c Separator 113 Powder supply device 113a Supply port 11a Pipe 12 Powder inlet 121 Passage 12a Inlet 12b Discharge port 12c Powder contact section 13 Powder conveying section 131 Flow path 13a Pipe 13b Carry-in port 14 Powder discharge section 1a Powder pipe 1m Main tank opening/closing valve 1n Mixing tank opening/closing valve 2 Paint discharge mechanism 24 Paint discharge section 2a Paint pipe A Coating device C Cart D1 Vertical direction D11 Vertical downward D12 Vertical upward D2 Direction in which flow path extends D21 Conveying direction G1 Compressed gas to the powder supply section G2 Compressed gas flowing through the flow path N Normal to the powder contact section R Rotating body S1 Powder S2 Paint T Target X1 Central axis of the target X2 Rotation axis of the screw Y1 Central axis of the passage on the powder conveying section side Y2 Central axis of the passage on the powder supplying section side α Angle made by the normal to the powder contact section with respect to the vertical downward direction D11 β1 Angle made by the central axis of the passage on the powder conveying section side and the conveying direction β2 Angle made by the central axis of the passage on the powder supplying section side and the conveying direction

Claims (3)

A powder discharging mechanism that uses compressed gas to discharge powder toward a target,
A powder supply unit that supplies the powder at a predetermined supply amount;
a powder conveying unit having a flow path for the compressed gas that extends vertically below the powder supplying unit and intersects with the vertical direction, and conveys the powder in a conveying direction along the flow path by the compressed gas flowing in the flow path;
a powder input section that drops the powder from the powder supply section onto the powder transport section,
the powder input section has a powder inlet provided on the powder supply section side, a powder outlet provided on the powder transport section side, and a powder abutment section provided between the inlet and the outlet with which the powder dropped into the powder input section abuts; the powder input from the inlet abuts on the powder abutment section, thereby changing the direction of motion of the powder so as to increase at least the motion component in the transport direction, and then being discharged from the outlet, thereby being input into the flow path ;
The powder feed section includes a tubular passage connecting the feed port and the discharge port,
The passage is provided away from the powder supply portion . an angle between a central axis of the passage on the powder transport unit side and the transport direction is smaller than an angle between a central axis of the passage on the powder supply unit side and the transport direction;
The powder contact portion is formed by an inner surface of the passage located on the opposite side of the powder conveying portion side of the passage in the conveying direction.
2. The powder dispensing mechanism according to claim 1. The object is an inner surface of a tube,
the conveying direction is a direction along a central axis of the tube,
a powder discharge unit connected to the powder conveying unit in the conveying direction and configured to discharge the powder toward the target object;
The powder discharging mechanism according to claim 1 , wherein the powder discharging section discharges the powder toward the inner surface in a direction intersecting the conveying direction.

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