Dot marking and printing device

Abstract

To provide a dot printing and marking device that prevents disorder of printing and marking.SOLUTION: A dot printing and marking device 1 includes a coating chamber 2, a compressed air passage 3, a nozzle plate 10, and a discharge nozzle 11. The nozzle plate 10 includes an atomization nozzle 12. The atomization nozzle 12 has a laval nozzle structure including a throat part 26 having the smallest flow channel cross-sectional area in the atomization nozzle 12. The discharge nozzle 11 includes a step part 17.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a dot marking and printing device for printing and drawing figures by dot marks on products such as steel materials.

Background Art

[0002] Conventionally, this type of dot marking and printing device has a spray nozzle, a discharge nozzle suitable for dot printing at the tip of the spray nozzle, and has a double structure with an atomizing nozzle outside thereof, and a discharge control valve composed of a valve seat and a spherical valve body is formed inside the discharge nozzle. And, in order to spray paint to make dot printing using this structure, an air atomizing method is known in which compressed air is sent to the atomizing nozzle and high-speed air is sprayed onto the paint at the tip of the discharge nozzle to atomize it.

[0003] Further, the spherical valve body is integrally connected via a rod to the movable iron core of a vibration mechanism, for example, an electromagnetic solenoid. A paint chamber filled with pressurized paint is provided around the valve seat and the spherical valve body. The discharge control valve is opened and closed by the reciprocating motion of the movable iron core, and dot-like liquid paint is intermittently discharged from the discharge nozzle and atomized. In order to obtain a smaller paint particle diameter, higher-speed air may be used, but conventionally, the compressed air flowing through the atomizing nozzle has been relatively slow. Since the drying speed of the paint is improved when the particle diameter is small, it has been studied whether high-speed air can be used.

[0004] For example, in Patent Document 1, a dot printing device is disclosed that is provided with a double-tube nozzle having a compressed air jet outlet surrounding the discharge nozzle, and the discharge nozzle protrudes longer than the compressed air jet outlet by a predetermined distance. Although the dot printing device disclosed in Patent Document 1 is excellent as a structure of a single spray nozzle, it only accelerates low-speed fine particles of paint and prevents the growth of tailing by a method of ejecting compressed air immediately after the discharge of dot-like liquid paint is completed, and the problem that the compressed air itself is relatively slow has not been solved. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 5-185591 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] For these reasons, the atomizing nozzle employing a Laval nozzle structure was adopted to increase the speed of compressed air. However, the use of the Laval nozzle structure also created new problems. When a Laval nozzle structure is used in the atomizing nozzle, setting the position of the discharge nozzle is extremely delicate. For example, even a shift of 0.1 millimeters in the position of the discharge nozzle tip can significantly change the atomization state. The present invention has been made with these points in mind, and aims to provide a dot marking and printing device that employs a Laval nozzle structure, is capable of atomization with high-speed compressed air, and prevents irregularities in printing and marking by controlling the atomization state through the appropriate setting of the position of the discharge nozzle tip. [Means for solving the problem]

[0007] Therefore, the present invention relates to a dot marking and printing device equipped with a spray nozzle capable of producing dot marks and printing by discharging or stopping the discharge of dot-shaped printing paint, wherein the spray nozzle has an atomizing nozzle for atomizing the paint using compressed air, a discharge nozzle held substantially at the center of the atomizing nozzle and capable of discharging and stopping the discharge of the dot-shaped printing paint, and a paint chamber having a recessed portion into which the discharge nozzle fits. Compressed air passageIn a dot marking and printing device equipped with a wall that serves as a partition, the atomizing nozzle is equipped with a throat portion, and further the atomizing nozzle is a Laval nozzle structure in which the throat portion is configured to have the narrowest flow path cross-sectional area in the atomizing nozzle, and the discharge nozzle is equipped with a thin-walled portion having a discharge nozzle tip which is an opening for discharging the dot-shaped printing paint, and a thick-walled portion for connecting to the paint chamber, and further the discharge nozzle is equipped with a stepped portion around the entire circumference at the boundary between the thin-walled portion and the thick-walled portion, and the width of the step in the stepped portion is 2.5 percent or more of the length of the diameter of the thick-walled portion.

[0008] Furthermore, the dot-shaped marking and printing device of the present invention is characterized in that the outer surface of the thickened portion is threaded.

[0009] Furthermore, the tip of the discharge nozzle has a wall thickness of 0.02 mm or more and 0.15 mm or less, the distance from the step to the tip of the discharge nozzle is 1 mm to 2 mm, and the manufacturing tolerance of this distance is within plus or minus 0.05 mm.

[0010] Furthermore, in the dot marking and printing device of the present invention, the thick portion of The outer diameter is characterized by being 1.5 millimeters or less.

[0011] Furthermore, in the dot marking and printing device of the present invention, the dot marking and printing device The aforementioned It is characterized by comprising a nozzle plate that forms an atomizing nozzle. [Effects of the Invention]

[0012] The present invention relates to a dot marking and printing device equipped with a spray nozzle capable of producing dot marks and printing by discharging or stopping the discharge of dot-shaped printing paint, wherein the spray nozzle has an atomizing nozzle for atomizing the paint using compressed air, a discharge nozzle held approximately at the center of the atomizing nozzle and capable of discharging and stopping the discharge of dot-shaped printing paint, and a paint chamber having a recessed portion into which the discharge nozzle is fitted. Compressed air passage In a dot marking and printing device equipped with a partition wall, the atomizing nozzle has a throat section, and furthermore, the atomizing nozzle has a Laval nozzle structure in which the throat section is configured to have the narrowest flow path cross-sectional area in the atomizing nozzle, and the discharge nozzle has a thin-walled section equipped with a discharge nozzle tip which is an opening for discharging dot-shaped printing paint, and a thick-walled section for connecting to the paint chamber, and furthermore, the discharge nozzle has a stepped section around the entire circumference at the boundary between the thin-walled section and the thick-walled section, and the width of the step in the stepped section is 2.5 percent or more of the length of the diameter of the thick-walled section, so that a dot marking and printing device can be provided that can increase the flow velocity of compressed air passing through the atomizing nozzle and appropriately position the discharge nozzle tip.

[0013] Furthermore, since the dot marking and printing device of the present invention is characterized in that the outer surface of the thickened portion is threaded, it is possible to provide a dot marking and printing device that can adjust the position of the tip of the discharge nozzle.

[0014] Furthermore, the present invention is characterized in that the tip of the discharge nozzle has a wall thickness of 0.02 mm or more and 0.15 mm or less, the distance from the step to the tip of the discharge nozzle is 1 mm to 2 mm, and the manufacturing tolerance of the distance is within plus or minus 0.05 mm. Therefore, even if there is a manufacturing tolerance in the range of plus or minus 0.05 mm, the present invention can provide a dot-shaped marking and printing device that can position the tip of the discharge nozzle with respect to the step.

[0015] Furthermore, thick section ofSince the outer diameter is 1.5 millimeters or less, it is possible to provide a dot-shaped marking and a printing device that can avoid the influence on adjacent ejection nozzles due to deformation of the embedding portion caused by press-fitting into the embedding portion of the ejection nozzle.

[0016] Furthermore, in the present invention, the dot-shaped marking and the printing device are characterized by including a nozzle plate that forms an atomizing nozzle, so it is possible to provide a dot-shaped marking and a printing device in which the compressed air flow path and the compressed air passage can be freely designed.

Brief Description of the Drawings

[0017] [Figure 1] It is a schematic cross-sectional view showing an example of the dot-shaped marking and the printing device 1 according to the present embodiment. [Figure 2] It is an enlarged schematic cross-sectional view of the atomizing nozzle 12 of the dot-shaped marking and the printing device 1 in FIG. 1. [Figure 3] (X) is a front view showing the ejection nozzle 11 in FIG. 2 from the direction of the ejection nozzle tip 51, and (Y) is a rear view of the ejection nozzle 11 showing the same ejection nozzle 11 from the direction of the thick portion 16. [Figure 4] It is a perspective view showing the ejection nozzle 11 and the ejection nozzle 111 which is another example of the present embodiment. [Figure 5] It is a perspective view showing a positional relationship between the ejection nozzle 11 and the nozzle plate 10 by cutting out a part of the nozzle plate 10. [Figure 6] It is a schematic cross-sectional view showing a state of press-fitting the ejection nozzle 11 according to the present embodiment into the embedding portion 27. [Figure 7] The state of press-fitting in FIG. 6 is shown in a perspective view using the ejection nozzle 111 and omitting the press-fitting jig 110. [Figure 8] (X) is a cross-sectional view of the press-fitting jig 110 according to the embodiment of the present invention, and (Y) is a perspective view in which a part of (X) is cut out to visualize the cross-section. [Figure 9]Figure 9 is a schematic cross-sectional view illustrating the dot-shaped marking and printing device 1 shown in Figure 1. [Modes for carrying out the invention]

[0018] The details of embodiments of the present invention will be described below with reference to the drawings. First, the dot marking and printing device according to this embodiment will be described. Figure 1 is a schematic cross-sectional view showing the general internal structure of the dot marking and printing device 1. Figure 2 is an enlarged view of the atomizing nozzle 12 portion of Figure 1. Walls 18, etc., are omitted, and only the atomizing nozzle 12 and the discharge nozzle 11 are shown. Figure 3(X) shows the discharge nozzle 11 from the left direction in Figure 2, and Figure 3(Y) shows it from the right direction in Figure 2. Figure 4 is a perspective view showing the discharge nozzle 11 and another example of the discharge nozzle 111 of this embodiment. Figure 5 is a perspective view showing the positional relationship between the atomizing nozzle 12 and the discharge nozzle 11 of Figure 1 after cutting out the nozzle plate 10. Figure 6 is a cross-sectional view showing the process of press-fitting the discharge nozzle 11 into the embedded portion 27 in order to manufacture the dot marking and printing device 1 of Figure 1. Figure 7 is a perspective view showing the press-fitting process in Figure 6, but with a discharge nozzle 111 instead of discharge nozzle 11, and the press-fitting jig 110 is omitted from the illustration. In Figure 7, only the wall 18 is shown in cross-section to illustrate the press-fitting process. Figure 8(X) is a cross-sectional view of the press-fitting jig 110 in Figure 6, and (Y) is a perspective view showing a portion of the press-fitting jig 110 in (X) cut out. Figure 9 is a schematic cross-sectional view illustrating the dot-shaped marking and printing device 1 in Figure 1. In this disclosure, for the sake of clarity, when simply referred to as "upper side," it refers to the right side in Figures 1, 2, and 6, and to the upper side in Figure 9. When simply referred to as "lower side," it refers to the left side in Figures 1, 2, and 6, and to the lower side in Figure 9.

[0019] The dot marking and printing device 1 shown in Figure 1 consists of a paint chamber 2, a compressed air passage 3, a nozzle plate 10, a wall 18 separating the compressed air passage 3 from the paint chamber 2, and a discharge nozzle 11. First, the paint chamber 2 is provided to pump paint into a paint flow path 32 located inside the discharge nozzle 11, and is equipped with a discharge control valve 22 to control the pumping. The discharge control valve 22 may be electromagnetic. As shown in Figure 1, the discharge control valve 22 consists of a valve body 21 and a valve seat 20, and controls the interval at which paint is pumped into the discharge nozzle 11 sandwiched between the valve seat 20 by operating so that the valve body 21 is pressed against the valve seat 20 or has a gap. The valve body 21 is connected to a rod-shaped movable iron core 23 shown in Figure 1, and the other end of the movable iron core 23 is connected to a vibration mechanism 24, which controls the operation so that the valve body 21 is pressed against the valve seat 20 or has a gap. This causes the pressurized paint to be discharged from the discharge nozzle 11.

[0020] Next, the compressed air passage 3 and the compressed air flow path 30 will be described in detail. The compressed air passage 3 is a passage for introducing compressed air into the nozzle plate 10 from a compressed air supply source (not shown), such as an air compressor. The compressed air passage 3 is in communication with the compressed air flow path 30, which is provided in the same number as the discharge nozzles 11, and the compressed air flows from the compressed air passage 3 to the compressed air flow path 30. The compressed air passage 3 is formed by fitting the nozzle plate 10 onto the discharge nozzles 11, and the gap formed between them becomes the compressed air passage 3. Therefore, in order to ensure the airtightness of the compressed air passage 3 formed by fitting, a sheet 25, which has the function of a packing and is shown by a dotted line in Figure 1, is attached so as to be in close contact with the wall 18 on the paint chamber 2 side.

[0021] The compressed air passage 30 consists of an atomizing section 40, a throat section 26, and an air inlet section 42. The compressed air passage 30 is surrounded by the atomizing nozzle 12, which surrounds the discharge nozzle 11. Thus, the atomizing nozzle 12 has a double structure. The air inlet section 42 is the inlet section that introduces compressed air from the compressed air passage 3 into the compressed air passage 30. The air inlet section 42 is preferably cylindrical in shape to reduce pipe resistance, and may be omitted depending on the design requirements of the discharge nozzle 11.

[0022] Next, the atomizing section 40 will be described with reference to Figure 1. The atomizing section 40 is the part where the paint is atomized by the discharge nozzle 11 and compressed air. It is preferable that the atomizing section 40 has a wider flow path cross-sectional area than the area near the throat section 26. By forming it in this way, the compressed air is accelerated in the atomizing section 40, and when the paint is discharged from the discharge nozzle 11, the paint droplets can be atomized to a smaller particle size, which is preferable.

[0023] Next, we will discuss the wall portion 31, which is a wall separating the two compressed air passages 30. Conventionally, the wall portion 31 was provided on both sides of each compressed air passage 30, but this configuration resulted in two walls 31 being provided between adjacent compressed air passages 30, creating wasted space. By providing the wall portion 31 as a single wall separating the two compressed air passages 30 on the nozzle plate 10, as in the nozzle plate 10, the width of the pitch Z between the discharge nozzles 11 can be significantly reduced compared to conventional designs. In Figure 1, a pitch Z of 1 to 6 millimeters is preferable.

[0024] The nozzle plate 10 will be described in more detail with reference to Figure 1. The compressed air passage 3 has a hole for introducing air from the outside by an air compressor (not shown). As shown in Figure 1, the compressed air passage 3 is in communication with multiple compressed air passages 30.

[0025] To further explain the positional relationship in which these components are connected, starting from the bottom and moving upwards in Figure 1, the compressed air passage 3 first connects to the compressed air inlet 42 of the compressed air passage 30 from the end of the nozzle plate 10, which is at the bottom of Figure 1, and then connects to the compressed air inlet 42 of the compressed air passage 30 of the other spray nozzles.

[0026] This configuration, in which the compressed air passage 3 communicates with multiple compressed air passages 30, allows compressed air to be supplied to multiple compressed air passages 30 simultaneously from a single compressed air supply source.

[0027] Next, the path through which the compressed air passes will be described in detail. First, compressed air flows into the compressed air passage 3 from an air compressor (not shown) through a hole (not shown). Then, in the atomizing nozzle 12, the compressed air flows from the compressed air passage 3 into the compressed air inlet 42, passes through the compressed air flow path 30, goes through the throat section 26 and atomizing section 40, and is ejected from the compressed air outlet 52. In the atomizing section 40, droplets of paint are discharged from the tip of the discharge nozzle 51, and the compressed air atomizes and accelerates them.

[0028] Next, the throat section 26 of the atomizing nozzle 12 will be described with reference to Figure 2. The atomizing nozzle 12 has a Laval nozzle structure in which the compressed air introduction section 42 has a wide flow path cross-sectional area, the flow path cross-sectional area is narrowest at the throat section 26, and widens towards the atomizing section 40. By adopting a Laval nozzle structure, the speed of the compressed air after the throat section 26 can exceed the speed of sound, so the particle size of the paint discharged from the discharge nozzle 11 can be reduced, which is preferable.

[0029] Furthermore, as shown in Figure 2, the discharge nozzle 11 includes a thin-walled section 15 and a thick-walled section 16, and a stepped section 17 is provided at the boundary between the thin-walled section 15 and the thick-walled section 16. The thickness of the thin-walled section 15 is preferably 0.02 millimeters to 0.15 millimeters. Figure 3(X) is a front view of the discharge nozzle 11 as seen from the direction of the discharge nozzle tip 51, and Figure 3(Y) is a rear view of the discharge nozzle 11 as seen from the direction of the thick-walled section 16, and is viewed from the opposite direction to Figure 3(X). As shown in Figure 3, the inner edge of the thin-walled section, the outer edge of the thin-walled section, and the outer edge of the thick-walled section, which are the outer edges of the paint flow path 32, are all configured concentrically from the center point O. The inner diameter of the discharge nozzle, which is the inner diameter of the flow path of the paint flow path 32 as shown in Figure 3(X), is preferably designed appropriately according to the amount of paint to be discharged, in the range of 0.1 millimeters to 0.2 millimeters. In this case, the outer diameter of the discharge nozzle tip is preferably 0.14 mm to 0.5 mm, and the wall thickness α of the thin-walled section 15 is preferably 0.02 mm to 0.15 mm. By configuring it in this way, the factors that obstruct the flow of compressed air can be reduced, and as a result, a smaller particle size can be obtained.

[0030] Furthermore, by making the thin-walled portion 15 so thin, if the press-fitting into the embedded portion 27, as described later, is performed by pressing only the thin-walled portion 15, there is a risk that the thin-walled portion 15 may deform. Therefore, it is preferable to provide a stepped portion 17 and press-fit the portion by pressing the stepped portion 17, as this allows the positioning of the discharge nozzle tip 51 to be performed using the stepped portion 17 as a reference. In order to use the stepped portion 17 as a reference for positioning, it is preferable that the distance V, which is the length between the stepped portion 17 and the discharge nozzle tip 51 as shown in Figure 2, is 1 to 2 millimeters and that the manufacturing tolerance is within the range of plus or minus 0.05 millimeters. By providing the stepped portion 17 with a step at a distance V of 1 millimeter or more, the degree to which the airflow is obstructed can be significantly reduced, and by having a distance V of 2 millimeters or less, it becomes easier to position the discharge nozzle tip 51.

[0031] Next, the stepped portion 17 will be described in more detail with reference to Figure 3(X). The width β of the step in the stepped portion 17 is preferably 2.5 percent or more of the length of the outer diameter Σ of the thickened portion 16 shown in Figure 3(Y). This configuration of the step width β is preferable because it makes it easier to press the thickened portion 16 into the embedded portion 27. Also, as shown in Figure 4 and Figure 3(Y), when the pitch Z of the arrangement of the discharge nozzles 11, 111 is 2 millimeters or less, the outer diameter Σ of the thickened portion 16 is preferably 1.5 millimeters or less, and more preferably 1 millimeter or less. If the outer diameter Σ of the thickened portion is larger than this, the deformation of the wall 18 may affect the position of the discharge nozzle tip 51 of the adjacent discharge nozzle 11, 111. The same applies to the thickened portion 116.

[0032] Next, with reference to Figure 4, the discharge nozzle 11 and the discharge nozzle 111, which is another example of this embodiment, will be described in detail. Corresponding to the fact that the discharge nozzle 11 has a thin-walled portion 15, a thick-walled portion 16, and a stepped portion 17, the discharge nozzle 111 also has a thin-walled portion 115, a thick-walled portion 116, and a stepped portion 17. The difference between the discharge nozzle 11 and the discharge nozzle 111 is that, in the discharge nozzle 111, only the area near the tip 51 of the discharge nozzle is tapered at an angle towards the discharge direction, whereas in the discharge nozzle 11, the entire thin-walled portion 15 is gently tapered towards the discharge direction. Secondly, the thick-walled portion 16 of the discharge nozzle 11 is simply cylindrical, whereas the thick-walled portion 116 of the discharge nozzle 111 is machined to have a thread in part. The thread may be an incomplete thread or a complete thread, and the machining method may be a known method such as rolling or cutting, which can be appropriately selected. Furthermore, in the descriptions and diagrams in this disclosure that use the discharge nozzle 11, it is equally preferable to use the discharge nozzle 111 instead. In other respects, there is no difference between the discharge nozzle 11 and the discharge nozzle 111.

[0033] Furthermore, it is equally preferable to combine the two configurations, such as making only the area near the tip 51 of the discharge nozzle, like the thin-walled portion 115 of the discharge nozzle 11, tapered. By configuring it in a tapered shape, it becomes easier to insert the press-fitting jig 110 into the thin-walled portions 15 and 115 of the discharge nozzles 11 and 111. Also, when press-fitting the discharge nozzles 11 and 111 into the embedded portion 27 using the press-fitting jig 110 as shown in Figure 6, not only the stepped portion 17 but also the tapered portion is pressed by the press-fitting jig 110. This increases the load-bearing capacity when press-fitting the discharge nozzles 11 and 111 without deformation, which is preferable. For this reason, it is even more preferable that the tapered portion of the press-fitting jig 110 is also configured to follow the thin-walled portions 15 and 115 of the discharge nozzles 11 and 111.

[0034] Next, with reference to Figure 5, the positional relationship between the discharge nozzle 11 and the atomizing nozzle 12 will be described in detail. As already explained, the atomizing nozzle 12 has a Laval nozzle structure in which the flow path cross-sectional area is narrowest at the throat section 26, and wider at the other parts. The discharge nozzle tip 51 is located near the throat section 26. Near the throat section 26, the flow velocity of the compressed air exceeds the speed of sound, so even a 0.1 mm shift in the position of the discharge nozzle tip 51 will cause a large shift in the printed pattern of the paint discharged from the discharge nozzle 11. For this reason, the positioning of the discharge nozzle tip 51 is particularly important.

[0035] Figure 6 is a cross-sectional view showing how the discharge nozzle 11 is pressed into the embedded portion 27 of the wall 18 by the press-fitting jig 110. The embedded portion 27 is provided in the wall 18 and communicates with the paint chamber 2. It is designed so that the paint from the paint chamber 2 can be pumped into the paint flow path 32 of the discharge nozzles 11,111 by fitting the discharge nozzles 11,111 into it. First, the procedure for pressing the discharge nozzle 11 into the embedded portion 27 will be described in detail with reference to Figure 6. First, the discharge nozzle 11 is fitted into the press-fitting jig 110 from the side of its thin-walled portion 15. Next, while gripping the press-fitting jig 110, the thick-walled portion 16 of the discharge nozzle 11 is pressed against the embedded portion 27 and pressed in. Next, the pressing is completed when the press-fitting jig 110 comes into contact with the wall 18. After the pressing is completed, the press-fitting jig 110 is removed from the discharge nozzle 11. Figure 7 shows the procedure when the press-fitting jig 110 is omitted and the discharge nozzle 111 is used instead of the discharge nozzle 11.

[0036] Figure 7 shows the press-fitting direction X of the discharge nozzle 111 and illustrates the process of press-fitting the discharge nozzle 111 into the embedded portion 27. As shown in Figure 7, the discharge nozzle 111 is press-fitted into the embedded portion 27 provided in the wall 18 using a press-fitting jig 110 (not shown), with the press-fitting direction being the press-fitting direction X. In Figure 7, only a cross-section of the wall 18 is shown. At this time, due to manufacturing errors, the position of the discharge nozzle tip 51 may be off from the design. If the position of the discharge nozzle tip 51 is off, the atomizing nozzle 12 has a Laval nozzle structure, and the flow of compressed air near its throat portion 26 can exceed the speed of sound. Therefore, even a slight shift in the position of the discharge nozzle tip 51 can result in a large shift in the direction of paint discharge, changing the printing performance. After press-fitting the discharge nozzle 111, the position of the discharge nozzle tip 51 can be adjusted by using a screw provided on the thickened portion 116 to rotate the discharge nozzle 111 in the W or Y direction, which is circumferential to the X direction.

[0037] To adjust the position of the discharge nozzle tip 51 in response to this misalignment, the screw pitch is preferably 0.15 mm and ~0.2 mm when the outer diameter of the thickened portion 116 is 0.6 mm to 0.8 mm. When the screw pitch is 0.15 mm, the discharge nozzle tip 51 can be moved by approximately 0.02 mm in the press-fit direction or the opposite direction by rotating the discharge nozzle 111 by 45 degrees. Providing the screw in the thickened portion 116 in this way allows the position of the discharge nozzle tip 51 to be adjusted in increments of 0.01 mm, which is preferable.

[0038] Next, the press-fitting jig 110 of the present invention will be described in detail with reference to Figure 8. As shown in Figure 8(X), the press-fitting jig 110 has a step support 120. As shown in Figure 6, the step support 120 presses the stepped portion 17 with its surface. The shape of the step support 120 may be flat or inclined, as long as it can press the stepped portion 17 with its surface, but as shown in Figure 8(Y) and Figure 6, it is preferable for pressing to be formed so as to intersect perpendicularly with the press-fitting direction X. The length from the step support 120 to the opening of the press-fitting jig 110 is designed as appropriate, but it is a predetermined length in order to position the tip 51 of the discharge nozzle when pressing the discharge nozzles 11, 111.

[0039] The press-fitting jig 110 is preferably made of a material that has high hardness and strength, is resistant to deformation under load, and has low thermal expansion. Specifically, alloy tool steel (SKD11) is a highly hard alloy with excellent wear resistance, and its coefficient of linear expansion is not high at 11.7 × 10⁻⁶ / °C. To minimize the influence of temperature during press-fitting, it is preferable to keep the length of the discharge nozzles 11, 111 that enter the press-fitting jig 110 as short as possible. Furthermore, a short length of the discharge nozzles 11, 111 that enter the press-fitting jig 110 makes it easier to position the discharge nozzle tips 51, which is also preferable. The parts of the discharge nozzles 11, 111 that enter the press-fitting jig 110 are mainly the thin-walled sections 15, 115. Therefore, it is preferable that the distance V, which is the length from the stepped section 17 to the discharge nozzle tip 51 as shown in Figure 2, is 2 millimeters or less, and that the manufacturing tolerance is within the range of plus or minus 0.05 millimeters.

[0040] Figure 9 is a schematic cross-sectional view showing the dot marking and printing device 1 according to this embodiment. As shown in Figure 9, a plurality of discharge nozzles 11 are arranged in a row. This allows the printing speed to be maintained at a high speed.

[0041] This disclosure can be suitably used for the purpose of printing or marking inspected printed objects. However, it is not limited to this use and can be broadly used in packages, inspected parts, and the like where dot markings and printing are required. [Explanation of symbols]

[0042] 1. Dot-shaped marking and printing device 2 Paint room 3 Compressed air passage 10 Nozzle Plates 11, 111 Discharge nozzle 12 Atomizing Nozzles 15,115 Thin-walled section 16,116 Thick wall part 17 Stepped section 18 Wall 20 valve seats 21 Valve body 22 Discharge control valve 23 Movable Iron Core 24 Vibration mechanism 25 seats 26 Throat section 27 Embedded part 30 Compressed air passage 31 Wall 32 Paint flow path 40 Atomizing section 42 Compressed air inlet 51 Discharge nozzle tip 52 Compressed air outlet 110 Press-fitting jig 120 Step supporter О Center point V distance X Press-fit direction Y, W rotation direction Z pitch

Claims

1. A dot marking and printing device equipped with a spray nozzle capable of producing dot marks and prints by discharging or stopping the discharge of dot-shaped printing paint, wherein the spray nozzle comprises an atomizing nozzle for atomizing the paint using compressed air, a discharge nozzle held approximately at the center of the atomizing nozzle and capable of discharging and stopping the discharge of the dot-shaped printing paint, and a wall having a recess into which the discharge nozzle fits, which serves as a partition between the paint chamber and the compressed air passage, The atomizing nozzle is equipped with a throat section, and furthermore, the atomizing nozzle has a Laval nozzle structure in which the throat section is configured to have the narrowest flow path cross-sectional area in the atomizing nozzle. The discharge nozzle has a thin-walled portion with a discharge nozzle tip which is an opening for discharging the dot-shaped printing paint, and a thick-walled portion for connecting to the paint chamber, and further the discharge nozzle has a stepped portion around the entire circumference at the boundary between the thin-walled portion and the thick-walled portion, and the width of the step of the stepped portion is 2.5 percent or more of the length of the diameter of the thick-walled portion, characterized in that a dot-shaped marking and printing device.

2. The dot-shaped marking and printing device according to claim 1, characterized in that the outer circumferential surface of the thickened portion is threaded.

3. The tip of the discharge nozzle has a wall thickness of 0.02 mm or more and 0.15 mm or less. The dot marking and printing apparatus according to claim 1 or 2, characterized in that the distance from the step to the tip of the discharge nozzle is 1 millimeter to 2 millimeters, and the manufacturing tolerance of the distance is within plus or minus 0.05 millimeters.

4. The dot marking and printing device according to claim 3, characterized in that the outer diameter of the thickened portion is 1.5 millimeters or less.

5. The dot marking and printing device according to claim 4, characterized in that the dot marking and printing device comprises a nozzle plate that forms the atomizing nozzle.

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