spray gun

Abstract

To provide a spray gun in which coating liquid or the like is unlikely to adhere a vicinity of a nozzle and which is capable of preventing contamination of foreign matter and a spray failure due to mist adhesion.SOLUTION: A spray gun 1 has: a nozzle 6 provided with a liquid discharge port 38 discharging spray liquid; and an air cap 3 which is provided with a nozzle insertion hole 53 where the nozzle 6 is disposed and has no projection part on a front end surface 52. The air cap 3 has: an atomizing air jet port 54 jetting atomizing air atomizing the spray liquid; and a pattern air jet port 57 jetting pattern air to a mist flow of the spray liquid. Two pairs of pattern air jet ports 57 are arranged each at opposite positions with a nozzle insertion hole 53 in between near the atomizing air jet port 67. The atomizing air jet port 67 and the pattern air jet port 57 are provided on the same surface of a flat surface part 61 formed on the front end surface 52 of the air cap 3.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a spray gun that atomizes and sprays a liquid onto an object to be treated, and in particular to a spray gun that is suitable for a powder and granular material processing apparatus that performs granulation, coating, etc. of powder and granular material such as tablets and powder. [Background technology]

[0002] Conventionally, in granulation and coating equipment (powder and granular material processing equipment) that performs processes such as granulation, coating, and drying of powder and granular material, liquid spraying using a spray gun has been widely used when coating powder and granular material. The spray gun of the powder and granular material processing equipment is usually placed in a processing vessel that contains powder and granular material, and uses compressed air to spray a binder liquid or coating liquid (hereinafter abbreviated as coating liquid, etc.) onto the powder and granular material that is in a fluidized or rolling state. Hot or cold air is supplied and exhausted as appropriate to the powder and granular material onto which the coating liquid, etc. has been sprayed, and processes such as forming a coating layer and drying are carried out.

[0003] Figure 11 is an explanatory diagram showing the configuration of a conventional spray gun. As shown in Figure 11, spray gun 101 has a nozzle 103 from which a coating liquid or the like is ejected, located in the center of an air cap 102 attached to the tip of the spray gun. Atomized air outlets 104 are provided around nozzle 103, from which atomized gas (atomized air) for atomizing the coating liquid or the like is ejected. A pair of pattern air ejection parts 105 are provided on the outside of atomized air outlet 104, protruding forward (in the spray direction of the coating liquid or the like; hereinafter, the terms "front and back" will refer to this direction), and a pattern air ejection port 106 from which pattern air is ejected is provided at each tip of the part.

[0004] In the spray gun 101 of Fig. 11, a coating liquid or the like discharged from a nozzle 103 is atomized by atomized air supplied from an atomized air outlet 104 and sprayed toward the front of the nozzle. Compressed air (pattern air) is blown onto the mist flow of the atomized coating liquid or the like from a pattern air outlet 106 of a pattern air jetting unit 105. This pattern air adjusts the cross-sectional shape of the mist flow, forming a spray pattern such as an ellipse or oval, while the coating liquid or the like is sprayed onto the object to be treated, such as a tablet. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6392177 [Patent Document 2] U.S. Patent No. 7,052,954 [Patent Document 3] JP 2011-530602 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, with a conventional spray gun 101 like the one shown in Figure 11, pattern air is directed from the pattern air nozzle 106 onto the mist stream from the side to form a spray pattern, resulting in air streams from different directions colliding in front of the nozzle 103. That is, with the spray gun 101, the pattern air strikes the mist stream flowing forward from the side, which can cause turbulence in the air stream in front of the nozzle. When turbulence occurs near the nozzle in this way, there is a risk that the mist of coating liquid or the like will fly in unintended directions or that air pockets with no air flow will form, causing problems such as mist adhering to the area around the nozzle and soiling the air cap 102.

[0007] In particular, conventional spray guns 101 have a problem in that the pattern air outlet 105 protrudes like a horn toward the front of the air cap, making it easy for mist to adhere there, resulting in the accumulation and growth of mist residue like stalactites. In this case, if the adhered mist peels off and falls into the powder or granular material being processed, there is a risk of foreign matter being mixed into the product. Furthermore, if the air cap 102 is easily soiled, the spray gun 101 must be cleaned more frequently, resulting in increased labor hours and reduced productivity. Furthermore, if mist adheres near the nozzle 103 or atomizing air outlet 104, it can make it difficult for the coating liquid or the like to be sprayed, potentially resulting in spray failure. This phenomenon is particularly likely to occur when continuously spraying viscous liquids, and a solution to this problem was needed.

[0008] An object of the present invention is to provide a spray gun that is less likely to have coating liquid or the like adhere to the vicinity of the nozzle and can prevent contamination by mist or spraying problems. [Means for solving the problem]

[0009] The spray gun of the present invention is a spray gun having a nozzle with a liquid discharge port from which a spray liquid is discharged, and an air cap having a nozzle insertion hole in which the nozzle is disposed and having no protrusions on its front end surface, wherein the air cap has an atomizing air discharge port from which atomizing air is ejected to atomize the spray liquid discharged from the liquid discharge port, and a pattern air discharge port from which pattern air is ejected toward a mist flow of the atomized spray liquid, the nozzle insertion hole being formed in the center of the air cap, the atomizing air discharge port being formed around the tip of the nozzle housed in the nozzle insertion hole, and a plurality of pattern air discharge ports are provided, and in the vicinity of the atomizing air discharge port: On the same circumference with the center of the nozzle insertion hole as the center At positions facing each other across the nozzle insertion hole Two by two, close together It is characterized by being arranged.

[0010] In the present invention, multiple pattern air nozzles are arranged near the atomizing air nozzle, facing each other across the nozzle insertion hole, eliminating the angular pattern air nozzles found in conventional spray guns. This prevents the spray liquid from adhering to the protruding parts, reduces the risk of mist accumulation near the front end face, and reduces the risk of turbulence in front of the nozzle. As a result, compared to conventional spray guns, mist adhesion to the liquid discharge port, the vicinity of the atomizing air nozzle, and the front end face of the air cap is reduced.

[0011] In the spray gun, the atomizing air outlet and the pattern air outlet may be provided on the same plane as a flat portion formed on the front end face of the air cap.Alternatively, the front end face of the air cap may be formed into a spherical shape, and the atomizing air outlet and the pattern air outlet may be provided near the apex of the spherical front end face.

[0012] moreover , close The patterned air injection ports may be arranged at intervals of 10° to 30°, preferably 15° to 25°, along the circumferential direction.

[0013] The air cap may be provided with pattern air passage holes for supplying the pattern air to the pattern air ejection nozzle, the pattern air passage holes being arranged radially from the nozzle insertion hole and tilted at an angle of 30° to 70° with respect to the axial direction. In this case, the pattern air may be ejected from the plurality of pattern air ejection nozzles toward the center of the spray gun. [Effects of the Invention]

[0014] In the present invention, a spray gun has a nozzle with a liquid discharge port, and an air cap with a nozzle insertion hole in which the nozzle is placed and no protrusions on its front end surface, and the air cap is provided with an atomized air outlet from which atomized air is sprayed, and a pattern air outlet from which pattern air is sprayed, and multiple pattern air outlets are arranged in positions opposite each other near the atomized air outlet, with the nozzle insertion hole in between, so that it is possible to eliminate the pattern air outlet that extends like a corner, which was found in conventional spray guns, and it is possible to prevent the spray liquid from adhering to the vicinity of the nozzle, thereby avoiding spraying problems such as difficulty in spraying the spray liquid. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a cross-sectional view showing the configuration of a spray gun according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a perspective view showing the configuration of an air cap used in the spray gun of FIG. 1. [Figure 3] 3A is a plan view of the air cap of FIG. 2, and FIG. 3B is a cross-sectional view taken along line AA of FIG. [Figure 4] (a) is a graph showing the relationship between liquid velocity and mist diameter when the atomizing air is set to 50 L / min and the pattern air is changed, and (b) is a graph showing the relationship between liquid velocity and mist diameter when the pattern air is set to 120 L / min and the atomizing air is changed. [Figure 5] 1A and 1B are explanatory diagrams showing spray patterns produced by a spray gun, where (a) shows the spray pattern when the pattern does not break, and (b) shows the spray pattern when the pattern breaks and forms two peaks. [Figure 6] FIG. 4 is a cross-sectional view showing the configuration of a spray gun according to a second embodiment of the present invention. [Figure 7] FIG. 8 is a perspective view showing the configuration of an air cap used in the spray gun of FIG. 7. [Figure 8] 8(a) is a plan view of the air cap of FIG. 7, and (b) is a cross-sectional view taken along line BB in (a). [Figure 9]FIG. 10 is a perspective view showing the configuration of an air cap used in a spray gun according to a third embodiment of the present invention. [Figure 10] 10(a) is a plan view of the air cap of FIG. 9, and (b) is a cross-sectional view taken along line CC in (a). [Figure 11] FIG. 1 is an explanatory diagram showing the configuration of a conventional spray gun. DETAILED DESCRIPTION OF THE INVENTION

[0016] (Embodiment 1) Hereinafter, embodiments of the present invention will be described. Fig. 1 is a cross-sectional view showing the configuration of a spray gun 1 according to a first embodiment of the present invention. The spray gun 1 of Fig. 1 is installed in a pan coating apparatus used, for example, in the manufacture of pharmaceuticals, foods, etc. The spray gun 1 is installed in a processing container of the pan coating apparatus, and sprays a coating liquid or other spray liquid onto objects to be processed (tablets, gum, chocolate, etc.) in the container.

[0017] As shown in Figure 1, spray gun 1 is equipped with a body block 2, air cap 3, cap nut 4, and cylinder cap 5, and is approximately 100 mm long. A nozzle 6, needle valve 7, and piston 8 are housed within the stainless steel body block 2. The air cap 3 is attached to the front side of the body block 2 via the cap nut 4, and the cylinder cap 5 is attached to the rear side. Spray gun 1 is attached to a spray gun support holder provided in the coating device using an attachment portion (such as an internally threaded hole) not shown provided on the body block 2.

[0018] In the spray gun 1, a spray liquid such as a coating liquid is sprayed from the center of the air cap 3 by a nozzle 6. Atomized air A is sprayed from the center of the air cap 3 together with the spray liquid. The spray liquid is atomized (atomized) by the atomized air A. Pattern air P is sprayed toward the spray flow (spray mist flow M) of the atomized spray liquid. The pattern air P is sprayed from the front end face of the air cap 3 toward the spray mist flow M. The spray mist flow M is sprayed onto the object to be treated, such as tablets, while a desired spray pattern is formed by the pattern air P.

[0019] The body block 2 is provided with a liquid supply port 11 through which the spray liquid is supplied, an atomizing air supply port 12 through which atomizing air A is supplied, and a needle air supply port 13 through which needle air for driving the needle valve 7 is supplied. The cap nut 4 is also provided with a pattern air supply port 14 through which pattern air P is supplied. A liquid tube 15b, an atomizing air tube 16b, a pattern air tube 17b, and a needle air tube 18b are connected to each of the supply ports 11 to 14 via joints 15a, 16a, 17a, and 18a, respectively.

[0020] A needle hole 21 is formed penetrating the center of the body block 2 in the left-right direction in FIG. 1. A needle valve 7 is inserted into the needle hole 21 in a state where it can move left-right. The left side of the needle hole 21 has an expanded diameter, forming a nozzle mounting portion 22. A nozzle 6 is attached to the nozzle mounting portion 22. A liquid flow path 23 is formed penetrating the center of the nozzle 6 in the axial direction. The needle valve 7 is inserted and disposed within the liquid flow path 23.

[0021] A cap nut 4 is attached to the left end of the body block 2. A male-threaded cap nut attachment portion 24 is formed on the outer periphery of the left end of the body block 2, and the cap nut 4 is screwed onto the cap nut attachment portion 24. An air cap 3 is attached to the front side (left side in the figure) of the cap nut 4. An engagement portion 25 is formed on the right end of the air cap 3, and this engagement portion 25 engages with an inner flange portion 26 formed on the left end of the cap nut 4. The cap nut 4 houses the air cap 3 and is attached to the cap nut attachment portion 24 with the engagement portion 25 engaged with the inner flange portion 26.

[0022] The nozzle 6 is clamped between the left end of the body block 2 and the right end of the air cap 3 by the cap nut 4. In the spray gun 1, the nozzle 6 and air cap 3 are placed on the left end face 27 of the body block 2, and the cap nut 4 is attached to cover them. The cap nut 4 is then screwed onto the cap nut attachment portion 24 and fixed. This secures the air cap 3 to the left end of the cap nut 4, and the nozzle 6 is clamped and fixed between the body block 2 and the air cap 3.

[0023] A piston 8 is fixed to the right end of the needle valve 7 in the figure. The piston 8 has a cylindrical body portion 31, around whose outer periphery an O-ring 32 is attached. Meanwhile, a cylinder cap attachment portion 33 is provided at the right end of the body block 2, to which a cylinder cap 5 is screwed and fixed. A cylindrical cylinder portion 34 is formed inside the cylinder cap 5, and the body portion 31 of the piston 8 is housed within the cylinder portion 34 so that it can slide left and right.

[0024] A piston spring 35 is attached to the right end of the piston 8. The left end of the piston spring 35 abuts against the body portion 31, and the right end abuts against the right end wall 36 of the cylinder portion 34. The cylinder cap 5 is screwed and fixed to the cylinder cap mounting portion 33 while compressing the piston spring 35. As a result, the piston 8 is housed in the cylinder cap 5 while being biased leftward by the piston spring 35.

[0025] A needle valve 7 is housed within the needle hole 21. The needle valve 7 and piston 8 are integrated, and the needle valve 7 moves left and right as the piston 8 moves. The left side of the needle valve 7 is inserted into the nozzle 6, and its left end forms a tapered needle valve portion 37. The needle valve portion 37 has a tapered shape and can be inserted and fitted into a liquid discharge port 38 formed in the tip 6a of the nozzle 6 (hereinafter referred to as the nozzle tip 6a). When the piston 8 moves left and right, the needle valve portion 37 of the needle valve 7 moves left and right within the liquid discharge port 38 accordingly. This movement of the needle valve portion 37 can be used to cut off the supply of spray liquid from the nozzle 6 or to change the opening of the liquid discharge port 38 to appropriately adjust the supply flow rate of the spray liquid.

[0026] Spray gun 1 is provided with a spray liquid flow path 41, an atomizing air flow path 42, a pattern air flow path 43, and a needle air flow path 44 as flow paths for supplying spray liquid and compressed air. Spray liquid flow path 41 extends upward from liquid supply port 11 in the figure and reaches needle hole 21 via a communication path 45 that extends diagonally upward within body block 2. It then passes through liquid flow path 23 formed in nozzle 6 and connects to liquid discharge port 38. Spray liquid supplied to liquid supply port 11 from liquid tube 15b via joint 15a passes through spray liquid flow path 41 and is discharged from liquid discharge port 38. At this time, the amount of spray liquid discharged from liquid discharge port 38 is appropriately controlled according to the operating position of needle valve 7 described above.

[0027] The atomized air flow path 42 extends downward in the figure from the atomized air supply port 12, passes through a communication passage 46 extending diagonally downward within the body block 2, passes through an atomized air flow path hole 47 on the outer periphery of the nozzle, and reaches the left end face 27 of the body block 2. A communication hole 49 is formed axially through the large-diameter portion 48 of the nozzle 6, facing the atomized air flow path hole 47, and the atomized air flow path 42 passes through this communication hole 49 and reaches an atomized air chamber 51 formed in the air cap 3. A nozzle insertion hole 53 communicating with the atomized air chamber 51 is formed in the front end face 52 of the air cap 3, and the atomized air flow path 42 connects to the nozzle insertion hole 53 in the center of the air cap. Compressed air supplied to the atomized air supply port 12 from the atomized air tube 16b via the joint 16a passes through the atomized air flow path 42 and is ejected from the nozzle insertion hole 53 as atomized air A.

[0028] In this case, the tip portion of the nozzle 6 (the left end in the figure) is housed within the atomizing air chamber 51, and atomizing air A is sprayed from around the nozzle tip 6a disposed within the nozzle insertion hole 53. That is, in the spray gun 1, the area around the nozzle tip 6a in the nozzle insertion hole 53 forms the atomizing air outlet 54. The spray liquid discharged from the liquid discharge port 38 of the nozzle 6 is atomized by the atomizing air A sprayed from the atomizing air outlet 54, and is sprayed in front of the spray gun 1 as a spray mist flow M.

[0029] The pattern air flow path 43 runs from the pattern air supply port 14 through a pattern air chamber 55 formed in the cap nut 4 to a pattern air flow path hole 56 formed in the air cap 3. A pattern air ejection port 57 is formed in the front end surface 52 of the air cap 3 and communicates with the pattern air flow path hole 56, and the pattern air flow path 43 continues from the pattern air flow path hole 56 to the pattern air ejection port 57. Compressed air supplied to the pattern air supply port 14 from the pattern air tube 17b via the joint 17a passes through the pattern air flow path 43 and is ejected from the pattern air ejection port 57 as pattern air P.

[0030] The needle air flow path 44 opens from the needle air supply port 13 through a needle air flow path hole 58 formed in the body block 2 into the cylinder portion 34. Needle air supplied to the needle air supply port 13 from the needle air tube 18b via the joint 18a passes through the needle air flow path 44 and is supplied into the cylinder portion 34. When needle air is supplied into the cylinder portion 34 through the needle air flow path 44, the pressure of the needle air compresses the piston spring 35, causing the piston 8 to move rightward in the figure. When the piston 8 moves rightward, the needle valve 7 also moves rightward. This causes the needle-shaped valve portion 37 of the needle valve 7 to move rightward, opening the liquid discharge port 38 of the nozzle 6.

[0031] In this type of spray gun 1, pattern air P is ejected from a pattern air outlet 57 provided on the front end surface 52 of the air cap. Figure 2 is a perspective view showing the configuration of the air cap 3 used in the spray gun 1, Figure 3(a) is a plan view of the air cap 3, and Figure 3(b) is a cross-sectional view taken along line AA in (a). As shown in Figures 2 and 3, the air cap 3 is provided with a nozzle insertion hole 53 in its center, within which the nozzle tip 6a is disposed. As described above, the atomized air outlet 54 is located on the outside of the nozzle tip 6a in the nozzle insertion hole 53.

[0032] 2 and 3, the front end face 52 of the air cap 3 has a flat, smooth surface 61 formed on the central side and a tapered, inclined surface 62 formed on the outer periphery. In the air cap 3, the atomizing air outlet 54 (nozzle insertion hole 53) and the pattern air outlet 57 are provided on the same plane as the flat surface 61 of the front end face 52. As shown in Fig. 2, in the spray gun 1, a plurality of pattern air outlets 57 are formed radially outward of the nozzle insertion hole 53.

[0033] The pattern air ejection ports 57 are arranged inside the boundary between the flat surface portion 61 and the inclined surface portion 62, in contact with the outer periphery of the flat surface portion 61, with pairs of pattern air ejection ports 57 facing each other across the nozzle insertion hole 53. The closely spaced pairs of pattern air ejection ports 57 are arranged on the same circumference centered on the central axis O of the nozzle insertion hole 53, with an interval θ1 of 10° to 30°, preferably 15° to 25° (20° here), along the circumferential direction. In this case, the pattern air ejection ports 57 may be arranged one by one facing each other, but arranging them two by two facing each other results in a better spread of the spray pattern.

[0034] 3, the pattern air flow path holes 56 opening into the pattern air ejection port 57 are formed at an angle θ2 of 30° to 70°, preferably about 45° (here, 43°), with respect to the axial direction (direction along the central axis O). The pattern air flow path holes 56 are formed in pairs radially opposite each other with respect to the center of the air cap 3, and the pattern air P is ejected from the pattern air ejection port 57 in the direction of the central axis O of the spray gun 1, that is, toward the center of the spray mist flow M (for example, ejected so as to be concentrated toward one target point T). This allows the pattern air P to be efficiently ejected into the spray mist flow M, making it easier to shape the cross-sectional shape of the mist flow into a desired shape.

[0035] Therefore, the pattern air P is applied to the spray mist flow M sprayed from the nozzle 6 at a downward angle of 43° toward the center of the mist flow. In this case, it is preferable that the pattern air P be applied to the spray mist flow M as close to the nozzle 6 as possible, but a larger application angle makes it more likely that turbulence will occur. For this reason, the inclination angle of the pattern air flow path hole 56 is preferably within the above-mentioned range. The cross-sectional shape of the spray mist flow M is deformed by this pattern air P, and is adjusted from its initial approximately circular shape to an elliptical or oval shape before being sprayed onto the object to be treated.

[0036] As such, spray gun 1 does not have the angular pattern air outlet 105 found in spray gun 101 of FIG. 11. Instead, pattern air P is sprayed from pattern air outlet 57, which is located on the same plane as the mist stream outlet. As a result, the spray liquid does not adhere to protruding parts, and because the air cap front end surface 52 is smooth, accumulation of the mist stream is unlikely to occur near the front end surface. Furthermore, because pattern air P strikes spray mist stream M from below, rather than from the side, it follows the flow, making it less likely to cause turbulence. As a result, spray gun 1 reduces mist adhesion near the liquid outlet and atomizing air outlet, and on the front end surface of the air cap, compared to conventional spray guns.

[0037] According to experiments conducted by the inventors using spray gun 1, an 8% aqueous solution of model coating liquid TC-5R (hydroxypropyl methylcellulose) was sprayed continuously for 9 hours at a liquid flow rate of 14 mL / min, atomizing air of 50 L / min, and pattern air of 120 L / min, but no adhesion of the spray liquid near the nozzle was observed, and there was no problem with spraying at all.

[0038] We also measured the spray mist diameter using normal water, and the mist diameter was within the practical range of 10 to 30 μm, and the mist diameter did not become irregular or large, resulting in no large mist. Figure 4(a) is a graph showing the relationship between liquid velocity and mist diameter when the atomizing air was set to 50 L / min and the pattern air was changed, and Figure 4(b) is a graph showing the relationship between liquid velocity and mist diameter when the pattern air was set to 120 L / min and the atomizing air was changed.

[0039] As can be seen from these graphs, the mist diameter from Spray Gun 1 was within the range of 10 to 30 μm. In this case, as shown in Figure 4(b), when the atomizing air volume was low relative to the spray liquid velocity, it was confirmed that the mist diameter increased as the liquid velocity increased, but it was found that a fine mist could be formed by providing a sufficient amount of air. Furthermore, even when the spray liquid velocity was increased, the mist diameter converged to around 8 to 10 μm.

[0040] Figure 5 is an explanatory diagram showing the spray pattern produced by a spray gun 1 according to the present invention. Figure 5(a) shows spray patterns obtained under conditions in which the pattern does not break up, and Figure 5(b) shows spray patterns obtained under conditions in which the pattern breaks up into two peaks. As shown in Figure 5(a), in experiments conducted by the inventors, a spray pattern with an oval cross section was formed without breakup when the liquid speed was 150 mL / min, atomizing air was 100 L / min, and pattern air was 120 L / min, and a pattern similar to that produced by a conventional spray gun was obtained, as shown in Figure 11.

[0041] On the other hand, it was confirmed that when the pattern air volume was relatively large compared to the atomizing air volume, the spray pattern split into two peaks, resulting in a two-peak mist distribution. That is, as shown in Figure 5(b), at a liquid velocity of 50 mL / min, atomizing air volume of 50 L / min, and pattern air volume of 120 L / min, a two-peak spray pattern was obtained, but it was found that spraying at a wide angle was possible.

[0042] In this way, the spray gun 1 of the present invention can suppress adhesion of the spray liquid near the nozzle while maintaining spray performance equivalent to that of conventional spray guns, making it possible to avoid spray problems such as difficulty in ejecting the spray liquid. In addition, because mist is less likely to adhere around the nozzle, the air cap is less soiled, preventing foreign matter from being mixed in due to adhering mist, and also preventing increased labor hours and reduced productivity due to frequent cleaning.

[0043] (Embodiment 2) Next, a spray gun according to a second embodiment of the present invention will be described. Fig. 6 is a cross-sectional view showing the configuration of a spray gun 71 according to the second embodiment of the present invention, Fig. 7 is a perspective view showing the configuration of an air cap 72 used in the spray gun 71, Fig. 8(a) is a plan view of the air cap 72, and Fig. 8(b) is a cross-sectional view taken along line BB in Fig. 8(a). In the following embodiment, parts and members similar to those of the spray gun 1 according to the first embodiment will be designated by the same reference numerals, and their description will be omitted.

[0044] In spray gun 71, the periphery of the front end of air cap 72 is spherical, unlike air cap 3. However, front end surface 73 of air cap 72 is a flat portion 74, and like air cap 3, atomized air outlet 54 (nozzle insertion hole 53) is provided in the center of flat portion 74. Meanwhile, the radially outer side of flat portion 74 is a spherical portion 75, and a patterned air outlet 57 is provided on the spherical portion 75 side of the boundary between flat portion 74 and spherical portion 75. Note that, like air cap 3 of embodiment 1, patterned air outlet 57 may be provided in flat portion 74 and arranged on the same plane as atomized air outlet 54.

[0045] In this case as well, the pattern air ejection ports 57 are provided in pairs facing each other with the nozzle insertion hole 53 in between. The closely spaced pairs of nozzle insertion holes 53 are spaced apart at the same angle as in the air cap 3 of embodiment 1. Furthermore, the pattern air flow path holes 56 are also inclined at the same angle as in the air cap 3, as shown in Figure 8(b).

[0046] In this type of spray gun 71, pattern air P is directed downward at an angle of 43° toward the spray mist stream M ejected from the nozzle 6, changing the cross-sectional shape of the spray mist stream M from a circular shape to an elliptical or oblong shape, and the spray mist stream M is sprayed onto the object to be treated. Similarly to the spray gun 1 of the first embodiment, the spray gun 71 also naturally prevents the spray liquid from adhering to protruding portions. Since the pattern air P strikes the spray mist stream M from below, rather than from the side, along the flow of the stream, turbulence is less likely to occur, and adhesion of mist to the liquid outlet 38, the vicinity of the atomizing air outlet 54, and the front end surface 52 of the air cap is also reduced. Therefore, adhesion of the spray liquid to the vicinity of the nozzle is reduced, making it possible to avoid spraying problems. Furthermore, since the air cap is less soiled, the introduction of foreign matter due to the adhering mist and the increased man-hours and reduced productivity associated with frequent cleaning are also reduced.

[0047] (Embodiment 3) Next, a spray gun according to a third embodiment of the present invention will be described. Fig. 9 is a perspective view showing the configuration of an air cap 82 used in a spray gun 81 according to the third embodiment of the present invention, Fig. 10(a) is a plan view of the air cap 82, and Fig. 10(b) is a cross-sectional view taken along line CC in Fig. 10(a). Note that the portions of the spray gun 81 other than the air cap 82 have the same configuration as the spray gun 71 according to the second embodiment.

[0048] The entire front end of the air cap 82 is spherical (spherical portion 83), and no flat portion is provided at the tip of the front end surface. The atomizing air outlet 54 (nozzle insertion hole 53) is provided at the vertex 84 of the spherical portion 83, and the pattern air outlet 57 is provided nearby. In the air cap 82, the pattern air outlets 57 are also provided in pairs facing each other across the nozzle insertion hole 53, and the closely spaced pair of nozzle insertion holes 53 are spaced at the same angular interval as in the air cap 3 of the first embodiment. Furthermore, as shown in FIG. 9(b), the pattern air flow path holes 56 are also inclined at the same angle as in the air cap 3. As described above, the use of the air cap 82 prevents the spray liquid from adhering to the vicinity of the nozzle.

[0049] The present invention is not limited to the above-described embodiment, and it goes without saying that various modifications can be made without departing from the spirit and scope of the present invention. For example, although the above-described embodiment shows an example in which the spray gun of the present invention is applied to a pan coating apparatus, the spray gun can also be applied to other powder and granular material processing apparatuses such as a fluidized bed apparatus. Also, the various numerical values shown in the above-described embodiment are merely examples, and the present invention is not limited to these numerical values.

[0050] 1 shows a configuration in which the atomizing air outlet 54 (nozzle insertion hole 53) and the pattern air outlet 57 are provided on the same surface of the flat portion 61, but the same effects as those of the above-described embodiment can be obtained even if the pattern air outlet 57 is located slightly lower than the atomizing air outlet 54 (for example, on the side of the sloped portion 62). Additionally, in the air cap 3, the outer periphery of the front end face 52 is sloped (sloped portion 62), but this portion may not be sloped, and the entire front end face 52 may be flat portion 61, and the air cap 3 may be formed into a cylindrical shape. [Industrial Applicability]

[0051] The present invention can be applied to devices other than powder and granular material processing devices, and can also be used in, for example, a line for painting automobiles, furniture, etc. [Explanation of symbols]

[0052] 1 spray gun 2. Body Block 3 bubble wrap 4 Cap nuts 5 Cylinder cap 6 nozzles 6a Tip 7 Needle Valve 8 pistons 11 Liquid supply port 12 Atomized air supply port 13 Needle air supply port 14 Pattern air supply port 15a Joint 15b Liquid tube 16a Joint 16b atomized air tube 17a Joint 17b pattern air tube 18a Joint 18b Needle Air Tube 21 Needle hole 22 Nozzle mounting part 23 Liquid flow path 24 Cap nut mounting part 25 Engagement part 26 Inner flange 27 Left end surface 31 Body 32 O-ring 33 Cylinder cap mounting part 34 Cylinder section 35 Piston spring 36 Right end wall 37 Needle valve 38 Liquid outlet 41 spray liquid flow path 42 Atomized air passage 43 pattern air flow path 44 Needle air passage 45 Communication path 46 Communication path 47 Atomized air passage hole 48 Large diameter section 49 Communication hole 51 Atomized Air Chamber 52 Air cap front end face 53 Nozzle insertion hole 54 Atomized air nozzle 55 pattern air chamber 56 pattern air flow holes 57 Pattern air nozzle 58 Needle air passage hole 61 Plane part 62 Slope 71 Spray gun 72 Bubble wrap 73 Air cap front end face 74 Plane part 75 Spherical part 81 Spray Gun 82 Bubble wrap 83 Spherical part 84 Vertices 101 Spray Gun 102 Bubble wrap 103 Nozzle 104 Atomized air nozzle 105 Pattern air outlet 106 pattern air nozzle Atomized Air M spray mist flow P Pattern Air O center axis T-pattern air injection target point θ1 Pattern air injection nozzle separation angle θ2 Pattern air flow hole inclination angle

Claims

1. a nozzle having a liquid outlet through which the spray liquid is discharged; a nozzle insertion hole into which the nozzle is disposed, and an air cap having no protrusion on a front end surface, the air cap has an atomizing air outlet through which atomizing air is ejected to atomize the spray liquid ejected from the liquid ejection port, and a pattern air outlet through which pattern air is ejected onto a mist flow of the atomized spray liquid, The nozzle insertion hole is formed in the center of the air cap, the atomizing air outlet is formed around the tip of the nozzle housed in the nozzle insertion hole, A spray gun characterized in that a plurality of the pattern air injection ports are provided, and two of them are arranged close to each other on the same circumference centered on the center of the nozzle insertion hole near the atomizing air injection port, facing each other across the nozzle insertion hole.

2. The spray gun of claim 1, a spray gun, characterized in that the atomizing air nozzle and the pattern air nozzle are provided on the same plane of a flat portion formed on the front end surface of the air cap;

3. The spray gun of claim 1, a front end surface of the air cap formed in a spherical shape, and the atomizing air outlet and the pattern air outlet are provided near the vertex of the spherical front end surface.

4. The spray gun according to any one of claims 1 to 3, A spray gun characterized in that adjacent pattern air injection ports are arranged at intervals of 10° to 30° along the circumferential direction.

5. The spray gun according to any one of claims 1 to 4, the air cap has a pattern air flow path hole for supplying the pattern air to the pattern air injection port, a nozzle insertion hole that is inclined at an angle of 30° to 70° with respect to the axial direction of the spray gun;

6. The spray gun according to claim 5, The spray gun is characterized in that the pattern air is sprayed from a plurality of the pattern air nozzles toward the center of the spray gun.

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