Dot marking and printing device and cleaning method thereof

Abstract

The present invention provides a dot-pattern printing and marking device that prevents paint deterioration due to heating, accelerates paint drying, and prevents irregularities in printing and marking. [Solution] The dot marking and printing device 1 comprises a main body 5, a paint chamber 2, a gas chamber 4, a heating element 12, a nozzle plate 10, a discharge nozzle 11, a compressed air passage 3, a compressed air flow path 30, and a cleaning plate 40. The heating element 12 is capable of heating the paint in the paint chamber 2 to a constant temperature, and the heating element 12 is made of a material that generates heat due to electrical resistance when an electric current is passed through it. The cleaning method 60 uses the dot marking and printing device 1 to fill the compressed air passage 3 and the compressed air flow path 30 with a cleaning agent 41, maintains the state in which the cleaning agent 41 is present due to the surface tension phenomenon, and continuously replenishes a very small amount of cleaning agent 41 that has decreased due to evaporation.

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, and a cleaning method thereof.

Background Art

[0002] Conventionally, this type of dot marking and printing device has a spray nozzle, and has a double structure with a discharge nozzle suitable for dot marking and printing at the tip of the spray nozzle and an atomizing nozzle on the outside thereof. A discharge control valve composed of a valve seat and a spherical valve body is formed inside the discharge nozzle. The spherical valve body is integrally connected to a movable iron core of a vibration mechanism, for example, an electromagnetic solenoid, via a rod. 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-shaped liquid paint is intermittently discharged from the discharge nozzle.

[0003] For example, Patent Document 1 discloses a marking device characterized by forming a valve body in a cylindrical shape, and forming a cylindrical hole-shaped guide portion within the valve housing into which the valve body is slidably fitted with a gap, wherein the gap between the guide portion and the valve body is a minute gap such that when the movable iron core is attracted by a solenoid and the valve body connected to the movable iron core opens, the force of the liquid flowing at high speed from the pressurized liquid-filled portion through the gap in the guide portion toward the nozzle inlet side leads the valve body in the direction of closing the valve seat. Because water-based paints have a slow evaporation rate of water, the drying time is extremely slow compared to solvent-based paints. Therefore, in the dot marking and printing device disclosed in Patent Document 1, especially when water-based paints are used, there remains a problem that the dot marking or dot printing may transfer or become unclear and illegible if the paint comes into contact with other materials before it is printed on the object to be printed and dries. The object to be printed is the object on which the dot marking or dot printing is drawn. Furthermore, temperature fluctuations in the surrounding environment due to seasons can result in temperature differences of more than 30 degrees Celsius between winter and summer. This temperature change alters the viscosity of the paint, which in turn significantly alters the amount of paint dispensed per application, resulting in a persistent problem of poor lettering quality. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2003-80133 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] The present invention has been made with these points in mind, and aims to provide a dot marking and printing device that can accelerate the drying of the paint in dot marking and printing, thereby preventing the printing on the printed object from transferring or becoming unclear, and that can maintain character quality by keeping the amount of paint discharged per application constant even with changes in ambient temperature. [Means for solving the problem]

[0006] Therefore, the present invention relates to a dot marking and printing device comprising a paint chamber for containing paint, a movable iron core, a valve body, a valve seat, a discharge nozzle, a compressed air passage, and at least one compressed air flow path, wherein a spherical valve body provided at the tip of the movable iron core has an open state in which it moves away from the valve seat and discharges from the paint chamber, and a closed state in which the valve body presses against the valve seat and stops discharge from the paint chamber, and by moving the device relative to the object to be printed and alternately transitioning between the open state and the closed state, it is possible to mark characters or figures with dots, wherein the paint chamber is equipped with a heating member, the heating member is configured to be energized by a power supply source, the heating member is a member that generates heat due to electrical resistance, and the heating member can heat the paint in the paint chamber and maintain it at a constant temperature.

[0007] Furthermore, the present invention is characterized in that the dot marking and printing device comprises a main body, a nozzle plate separate from the main body, and a cleaning plate, the compressed air passage is configured to be surrounded by the cleaning plate and the nozzle plate, the paint chamber is configured to be surrounded by the main body and the nozzle plate, the nozzle plate is provided with the discharge nozzle and the valve seat, the heating member is held so as to be fixed between the main body and the nozzle plate, and the heating member can be connected to a power supply source located outside the main body and the nozzle plate.

[0008] Furthermore, the present invention is characterized by providing an insulating sheet between the nozzle plate and the heating element, or between the main body and the heating element, at least one of the two locations.

[0009] Furthermore, the main body is characterized by being equipped with a gas chamber that communicates with the paint chamber.

[0010] Furthermore, the present invention relates to a method for cleaning a dot marking and printing device using the dot marking and printing device described in claim 2, comprising: a cleaning agent introduction step of introducing a cleaning agent into the compressed air passage; a cleaning agent replenishment step of maintaining the cleaning agent within the cleaning plate by utilizing the surface tension phenomenon of the cleaning agent occurring at the cleaning agent discharge port of the cleaning plate, and continuously replenishing the amount of cleaning agent that has decreased due to evaporation as the cleaning agent evaporates over time; and a cleaning agent removal step of introducing compressed air into the compressed air passage provided between the nozzle plate and the cleaning plate to remove the cleaning agent from the compressed air passage and the compressed air flow path, wherein the cleaning agent introduction step, the cleaning agent replenishment step, and the cleaning agent removal step are performed sequentially. [Effects of the Invention]

[0011] The present invention relates to a dot marking and printing device comprising a paint chamber for containing paint, a movable iron core, a valve body, a valve seat, a discharge nozzle, a compressed air passage, and at least one compressed air flow path, wherein a spherical valve body provided at the tip of the movable iron core has an open state in which it moves away from the valve seat to discharge paint from the paint chamber, and a closed state in which the valve body presses against the valve seat to stop discharge from the paint chamber, and by moving the device relative to the object to be printed and alternately transitioning between the open and closed states, it is possible to mark characters or figures with dots. The present invention relates to a dot marking and printing device comprising a heating element, the heating element being configured to be energized by a power supply source, the heating element being a component that generates heat due to electrical resistance, and the heating element being able to heat the paint in the paint chamber and maintain it at a constant temperature, thereby preventing deterioration of the paint outside the paint chamber, accelerating the drying of the paint, and preventing irregularities in dot marking and dot printing as much as possible, thereby providing a dot marking and printing device that maintains high printing quality.

[0012] Furthermore, the present invention provides a dot marking and printing device that comprises a main body, a nozzle plate separate from the main body, and a cleaning plate, wherein the compressed air passage is surrounded by the cleaning plate and the nozzle plate, the paint chamber is surrounded by the main body and the nozzle plate, the nozzle plate is provided with a discharge nozzle and a valve seat, and the heating element is held so as to be fixed between the main body and the nozzle plate, and the heating element is also connectable to a power supply source located outside the main body and the nozzle plate. Thus, the pitch between nozzles can be shortened, and the heating element connected to an external power supply source can be easily incorporated into the paint chamber.

[0013] Furthermore, the present invention is characterized by providing an insulating sheet between the nozzle plate and the heating element, or between the main body and the heating element, so that only the paint chamber can be heated, making it easier to control the heat, reducing the loss of energy for heating, and preventing current from flowing if the nozzle plate is a conductive material.

[0014] Furthermore, since the main body is equipped with a gas chamber that communicates with the paint chamber, it is possible to reduce the amount of paint that needs to be heated simultaneously, enabling temperature control in a short time, and providing a dot marking and printing device that prevents irregularities in dot markings and dot printing.

[0015] Furthermore, the present invention provides a method for cleaning a dot marking and printing device using the dot marking and printing device described in claim 2, comprising: a cleaning agent introduction step of introducing a cleaning agent into a compressed air passage; a cleaning agent replenishment step of maintaining the cleaning agent within the cleaning plate by utilizing the surface tension phenomenon of the cleaning agent that occurs at the cleaning agent discharge port of the cleaning plate, and continuously replenishing the amount of cleaning agent that has decreased due to evaporation as the cleaning agent evaporates over time; and a cleaning agent removal step of introducing compressed air into a compressed air passage provided between the nozzle plate and the cleaning plate to remove the cleaning agent from the compressed air passage and the compressed air flow path, wherein the cleaning agent introduction step, the cleaning agent replenishment step, and the cleaning agent removal step are performed sequentially, thereby preventing drying of the tip of the discharge nozzle, preventing irregularities in dot marking and dot printing, and providing a cleaning method for a dot marking and printing device that suppresses temperature rise. [Brief explanation of the drawing]

[0016] [Figure 1] This is a schematic cross-sectional view showing an example of a dot-shaped marking and printing device 1 according to this embodiment. [Figure 2] This is an example of a dot-shaped marking and printing device 1 according to this embodiment, and is a schematic cross-sectional view of the A-A section in Figure 1 as seen from the direction of the arrow. [Figure 3] Figure 1 shows the dot-shaped marking and printing device 1. For explanatory purposes, this is a schematic diagram showing a perspective view of the A-A section of Figure 1. [Figure 4] As another example of the dot marking and printing device according to this embodiment, Figure 1' shows a schematic cross-sectional view of the A-A section in Figure 1, taken from the direction of the arrow. [Figure 5] This is a flowchart illustrating the cleaning method 60 in this embodiment. [Figure 6]This figure shows the dot marking and printing devices 1,1' when the cleaning method 60 in this embodiment is performed, with (X) being a diagram before the procedure, (Y) being a diagram after the cleaning agent introduction step 61 is performed, and (Y) being a schematic cross-sectional view for explanation purposes showing the state after the cleaning agent removal step 63 is performed. [Modes for carrying out the invention]

[0017] The details of embodiments of the present invention will be described below with reference to the drawings. Figure 1 is a schematic cross-sectional view showing the general internal structure of the dot marking and printing device 1,1'. Only the cross-section is shown for illustrative purposes, and the heating element 12, etc., are omitted from the illustration. Figure 2 is a schematic cross-sectional view of the dot marking and printing device 1, which is an example of this embodiment, taken from the direction of the arrow on plane AA of Figure 1. Figure 3 is a schematic explanatory diagram illustrating the dot marking and printing device 1, which is shown as a perspective view by cutting out plane AA of Figure 1 for illustrative purposes. Note that in Figure 3, the sheet 25 and sealing sheet 26 are omitted from the illustration. Figure 4 is a schematic cross-sectional view of the dot marking and printing device 1', which is an example of this embodiment, taken from the direction of the arrow on plane AA of Figure 1. Figure 5 is a flowchart showing the cleaning method 60 in this embodiment. Figure 6 shows a schematic cross-sectional view of the dot marking and printing device 1 when the cleaning method 60 in this embodiment is performed. (X) is a diagram showing the state before the cleaning agent introduction step 61 and after the printing step is completed, (Y) is a diagram showing the state after the cleaning agent introduction step 61 and during the cleaning agent replenishment step 62, and (Y) is a schematic cross-sectional view for explanation showing the state after the cleaning agent removal step 63 has been performed. For the convenience of explanation in this disclosure, when simply referred to as the upper side, it refers to the upper side in Figures 1, 2, and 4, and when simply referred to as the lower side, it refers to the lower side in Figures 1, 2, and 4.

[0018] The dot marking and printing device 1 shown in Fig. 1 is provided with a paint chamber 2, a gas chamber 4, a wall 13, a vibration mechanism 24, a movable iron core 23, and a discharge control valve 22. The dot marking and printing device 1 shown in Fig. 1 and the dot marking and printing device 1' have the same configuration in the cross-section of Fig. 1, and the difference lies in the presence or absence of the insulating sheets 28, 28'.

[0019] First, although not shown in the figure, the paint chamber 2 is filled with paint. Either water-based paint or solvent-based paint may be used for the paint. However, this disclosure can be more preferably used in view of the fact that the drying time becomes long in the case of water-based paint. As shown in Fig. 1, a wall 13 is provided between the paint chamber 2 and the gas chamber 4. The gas chamber 4 is provided with a part of the vibration mechanism 24 and the movable iron core 23, but the method of providing the gas chamber 4 is not limited to this, and it may be provided at a position different from the vibration mechanism 24 and the movable iron core 23. The gas chamber 4 may be configured to apply pressure to the air filled in the gas chamber 4 from an external pressure source of the dot marking and printing devices 1, 1'. The paint chamber 2 and the gas chamber 4 communicate with each other through a hole 14.

[0020] Since the gas chamber 4 is provided to communicate with the paint chamber 2 through the hole 14, the air in the gas chamber 4 can apply pressure to the paint filled in the paint chamber 2, and the paint pressure can be ensured. By ensuring the paint pressure, the paint is smoothly discharged from the discharge nozzle 11, which is preferable. The air in the gas chamber 4 is under a pressure that compresses due to the pressure applied to the paint in the paint chamber 2. Therefore, the gas chamber 4 may be provided with a pressure source, or it may not be provided.

[0021] The paint in the paint chamber 2 is heated, so its viscosity is reduced. However, in the paint supply path outside the paint chamber 2, the viscosity is higher than that. Therefore, when the paint supply path is long, the paint supply during dot marking or dot printing may instantaneously become insufficient, causing a decrease in the paint pressure in the paint chamber 2 and resulting in disrupted dot marking or dot printing. To address this instantaneous pressure drop, it is preferable to provide a gas chamber 4 to respond to the instantaneous pressure drop. If the pressure of the gas chamber 4 is set to the same pressure source as the paint pressure when pumping the paint during paint supply, balance can be achieved, which is preferable.

[0022] Next, while referring to FIG. 1, the structure of the dot marking and printing devices 1, 1' will be described in further detail. First, the paint chamber 2 is provided to pump paint into the paint flow path 32 provided inside the discharge nozzle 11 and includes a valve body 21 and a valve seat 20 for controlling the pumping. The paint chamber 2 is filled with paint used for discharging through the discharge nozzle 11 for dot marking and dot printing. Between the paint chamber 2 and the paint flow path 32, which will be described later, in the closed state shown in FIG. 1, it is sealed and blocked by a spherical valve body 21. The movable iron core 23 is rod-shaped, with one end fixed to the vibration mechanism 24 and the valve body 21 fixed to the tip of the other end. The valve body 21 in the closed state seals the paint chamber 2 by pressing the valve seat 20 in the paint chamber 2 so that the paint in the paint chamber 2 does not leak. It is preferable to use an elastic material such as rubber or resin for the valve seat 20.

[0023] A paint flow path 32 is provided in the center of the valve seat 20, passing through the valve seat 20 vertically. The paint flow path 32 is formed inside the discharge nozzle 11. Specifically, first, the paint flow path 32 penetrates the central part of the valve seat 20. Then, this paint flow path 32, which is a pipe that penetrates the valve seat 20, is formed inside the discharge nozzle 11. This pipe inside the discharge nozzle 11 is also included in the paint flow path 32. However, the inlet of the paint flow path 32 on the paint chamber 2 side of the valve seat 20 can be opened and closed by the valve body 21. More specifically, the valve body 21 is provided so that it can be closed by pressing the valve seat 20 to block the inlet of the paint flow path 32 of the valve seat 20, and the inlet of the paint flow path 32 can be opened by moving away from the inlet of the paint flow path 32.

[0024] The dot marking and printing device 1,1' according to this embodiment will be described in more detail with reference to Figure 1. The dot marking and printing device 1,1' further includes a compressed air passage 3, a wall portion 31 separating the compressed air passage 3 from the paint chamber 2, a discharge nozzle 11, and a compressed air passage 30. First, the paint chamber 2 is provided to pump paint into a paint passage 32 located inside the discharge nozzle 11, and is equipped with a discharge control valve 22 to control the pumping. 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 seats 20 by the valve body 21 pressing against the valve seats 20 or operating so that there is 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 or has a gap with the valve seat 20. As a result, a certain amount of pressurized paint is discharged from the discharge nozzle 11. Here, the certain amount is the amount necessary to adhere dots for printing or drawing a figure to the object to be printed.

[0025] 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 structure is such that compressed air flows from the compressed air passage 3 to the compressed air flow path 30. The compressed air passage 3 is formed by joining the cleaning plate 40 to the lower side of the nozzle plate 10, 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 in this way, a sheet 25 that functions as a packing is attached so as to be in close contact with the wall portion 31. The nozzle plate 10 and the cleaning plate 40 may be joined by known methods, such as being in close contact via the sheet 25, or one of the nozzle plate 10 or the cleaning plate 40 being fitted into the other, as long as the nozzle plate 10 and the cleaning plate 40 are joined and become one unit.

[0026] Here, we will describe the nozzle plate 10 in detail. The nozzle plate 10 forms the lower part of the paint chamber 2 and is equipped with a valve seat 20, a discharge nozzle 11, and a wall portion 31. The discharge nozzle 11 is formed by cutting a cylindrical hole into the nozzle plate 10, and the wall portion 31 is formed so that the discharge nozzles 11 are separated from each other. Conventionally, the wall portion 31 was provided on both sides of each discharge nozzle 11, but with this configuration, two wall portions 31 were provided between adjacent discharge nozzles 11, resulting in wasted space. As with the nozzle plate 10, by providing the wall portion 31 on the nozzle plate 10 so as to separate two discharge nozzles 11, the pitch width between the discharge nozzles 11 can be greatly reduced compared to conventional designs.

[0027] Next, the cleaning plate 40 will be described in detail. The cleaning plate 40, together with the nozzle plate 10, forms a compressed air passage 3. A compressed air passage 30, which communicates with the compressed air passage 3, is provided in the cleaning plate 40. In other words, the cleaning plate 40 has a cylindrical hole for the compressed air passage 30.

[0028] Next, atomization will be explained. Atomization is the process of atomizing the paint discharged from the discharge nozzle 11 using compressed air in the compressed air passage 3 and compressed air flow path 30. Compressed air introduced into the compressed air passage 3 from the compressed air supply source accelerates and atomizes the paint droplets discharged from the discharge nozzle 11. This paint passes through the compressed air flow path 30 and is ejected from the compressed air outlet 52, which is its outlet, towards the object to be printed. However, dot marking and printing can also be performed by discharging paint droplets from the discharge nozzle 11 without atomization.

[0029] Next, the nozzle plate 10 will be described in more detail. The compressed air passage 3 has a compressed air inlet for introducing air from the outside by an air compressor or the like (not shown). As shown in Figure 1, the compressed air passage 3 is in communication with a plurality of compressed air passages 30. This configuration, in which the compressed air passage 3 is in communication with the compressed air passages 30, allows compressed air to be supplied to a large number of compressed air passages 30 at once from a single compressed air supply source.

[0030] Next, the path through which the compressed air passes will be described in detail. First, compressed air flows from an air compressor (not shown) through a compressed air inlet (not shown), which is a hole, into the compressed air passage 3. From the compressed air passage 3, the compressed air passes through the compressed air flow path 30 and is ejected from the compressed air outlet 52. In the compressed air passage 3, droplets of paint are discharged from the tip of the discharge nozzle 51, and the compressed air atomizes and accelerates them.

[0031] Next, the pitch between dots when paint droplets discharged from the dot marking and printing device 1 according to the present invention reach the object to be printed and adhere to it in a dot shape will be described in detail. Paint droplets discharged almost straight from the tip 51 of the discharge nozzle immediately reach the object to be printed and adhere to the object as dots, thereby performing marking or printing. Conventionally, because the width between the discharge nozzles 11 was wide, the dot pitch, which is the distance between dots formed by paint droplets discharged at one time adhering to the object to be printed, had to be correspondingly large. In contrast, when using the nozzle plate 10 of the present invention, if the outer diameter of the nozzle is set to 0.2 to 2 mm and the length of the discharge nozzle 11 is set to about 0.7 to 5 mm, it is possible to shorten the nozzle pitch, which is the distance between the discharge nozzles 11, by about 1 to 5 mm compared to conventional methods. In such cases, by configuring the device as the dot marking and printing device 1 of this disclosure and by devising the arrangement of the movable iron core 23 and the vibration mechanism 24, an even narrower dot pitch can be achieved. Specifically, while conventional dot pitches were approximately 3-5 mm, the present invention allows for a dot pitch as small as 1 mm. Furthermore, by providing the nozzle plate 10, maintenance is improved because the nozzle plate 10 can be easily replaced even if the discharge nozzle 11 becomes clogged.

[0032] Next, the dot marking and printing device 1 according to this embodiment will be described in more detail with reference to Figure 2. The dot marking and printing device 1 according to this embodiment includes a heating element 12 in the paint chamber 2. It is preferable to use a material that generates heat due to electrical resistance when electricity is passed through it as the heating element 12. Specifically, this could be a nichrome wire, but it is not limited to this as long as it is a material with electrical resistance. In this embodiment, the heating element 12 is used in the form of a coil with a diameter of about 0.1 millimeters, but the size and other aspects are not limited to this. In Figure 3, the heating element 12 is provided on both sides of the row in which the movable iron core 23 and vibration mechanism 24 are arranged, parallel to the direction in which the movable iron core 23 and vibration mechanism 24 are arranged, but the arrangement is not limited to this and can be designed as appropriate.

[0033] The heating element 12 makes it possible to heat the paint (not shown) inside the paint chamber 2 and maintain it at a constant temperature. Conventionally, a hot hose outside the dot marking and printing device 1,1' was used to heat the paint, but using a hot hose resulted in a larger volume of paint being heated than the amount inside the paint chamber 2. This sometimes led to accelerated deterioration of the paint. In addition, heating the paint meant that unless a path was provided to circulate the paint frequently, the paint components were more likely to settle. In this disclosure, the heating element 12 makes it possible to heat only the paint inside the paint chamber 2.

[0034] Furthermore, in the dot marking and printing device 1,1', the paint chamber 2 has a capacity of approximately 0.5cc to 5cc, and more preferably, approximately 1cc to 2cc. By using the heating element 12 and configuring the paint chamber 2 to be this small, it is possible to heat only a very small amount of paint. Since the rest of the paint does not need to be heated, paint deterioration is significantly reduced and paint sedimentation can be prevented, making this configuration preferable.

[0035] Furthermore, the constant temperature at which the paint is heated by the heating element 12 can be appropriately set to approximately 30 to 70 degrees Celsius. By setting a constant temperature, the same temperature can be maintained in both summer and winter. By heating the paint in the paint chamber 2 to a constant temperature, the viscosity of the paint is kept at a consistent level, resulting in a consistent amount of dots discharged from the discharge nozzle 11 each time, thus reducing irregularities in dot markings and dot printing. In addition, by heating the paint in the paint chamber 2 to a constant temperature, especially when using water-based paint, the drying of the paint can be accelerated, preventing the transfer or blurring of dot markings or dot printing on the printed object. By setting the constant temperature to 60 degrees Celsius or higher, the drying of the paint can be accelerated in particular.

[0036] Next, the main body 5 will be described in detail. The main body 5 has a gas chamber 4 and the upper part of the paint chamber 2. The main body 5 and the nozzle plate 10 are joined together, with the heating element 12 sandwiched between them to form the paint chamber 2. In other words, as shown in Figure 3, the main body 5, nozzle plate 10, and cleaning plate 40 are joined together to form the dot marking and printing device 1 according to this embodiment. The joining of the main body 5 and the nozzle plate 10 only needs to be done with an open space for the paint chamber 2. Other spaces, such as a gap 27, may be used, with a sealing sheet 26 sandwiched in between, and the joining may be done via the sealing sheet 26, or other known methods may be used, as long as the main body 5 and the nozzle plate 10 are joined together and become one unit. They may be joined by known methods, such as being tightly sealed via a sheet 25, or one of the nozzle plate 10 or cleaning plate 40 being fitted into the other.

[0037] The heating element 12 is held in place by being sandwiched between the main body 5 and the nozzle plate 10 so as to be fixed in place. In the dot marking and printing device 1,1' according to this embodiment, the heating element 12 uses a wire with a diameter of about 0.1 millimeters, coiled in shape. This thin wire is used to increase the electrical resistance. If the electrical resistance is high, the current that flows can be reduced to obtain the same amount of heat. A high current makes control difficult and costly. Therefore, it is preferable that the material used for the heating element 12 has a diameter of 0.2 millimeters or less. For this reason, it is preferable that the heating element 12 is held in place by being sandwiched between the main body 5 and the nozzle plate 10 so as to be fixed in place. If the heating element 12 is in a state where it can easily move, there is a risk of wire breakage if the wire used for the heating element 12 is thin.

[0038] It is preferable to use resin for the main body 5. The PPS resin used for the main body 5 is preferable because it has a thermal conductivity of approximately 0.2 to 0.3 W / (m / K) and an operating temperature of 220 degrees Celsius or less. In addition, PPS resin is resistant to many solvents. Furthermore, solvent-based paints may be placed in the paint chamber 2. For these reasons, it is preferable to use resin for the main body 5.

[0039] By keeping the thermal conductivity of the main body 5 low in this way, only the paint in the paint chamber 2 is heated, making heat diffusion less likely. This makes heat management easier and reduces energy loss for heating. If the thermal conductivity is too high, the heating element 12 may need to be made larger, so it is preferable to have a low thermal conductivity as described above.

[0040] Furthermore, by joining the nozzle plate 10 to the main body 5 to form the dot marking and printing device 1,1', a gap 27 is created, but it becomes easier to place the heating element 12 inside the paint chamber 2, therefore, using the nozzle plate 10 is preferable. Since the heating element 12 needs to be energized, it needs to be connected to a power supply outside the main body 5 and the nozzle plate 10. The dot marking and printing device 1,1' of this disclosure can be manufactured by sandwiching the heating element 12 between the nozzle plate 10 and the main body 5. Therefore, since the heating element 12 can be easily placed inside the paint chamber 2, using the nozzle plate 10 is preferable.

[0041] The paint chamber 2 and its gap 27 will be explained with reference to Figures 2 and 3. The main body 5 and the nozzle plate 10 are joined together, and a gap 27 is formed at the joint along with the paint chamber 2. This gap 27 is sealed by a sealing sheet 26 to seal the paint chamber 2.

[0042] Figure 4 shows another example of this embodiment, a dot marking and printing device 1'. The differences from the dot marking and printing device 1 in Figure 2 are that it is equipped with insulating sheets 28, 28', and that the gap 27 is filled with insulating sheets 28, 28' instead of the sealing sheet 26, but the other configurations are the same.

[0043] Next, the insulating sheets 28 and 28' will be explained with reference to Figure 4. The heating element 12 is equipped with an insulating sheet 28' between it and the main body 5 to prevent direct contact between the main body 5 and the heating element 12. Similarly, the heating element 12 is equipped with an insulating sheet 28 between it and the nozzle plate 10 to prevent direct contact between the nozzle plate 10 and the heating element 12. Figure 4 shows both insulating sheets 28 and 28', but it is sufficient to have at least one of them; for example, only insulating sheet 28 may be provided, and insulating sheet 28' may not be provided. By providing insulating sheets 28 and 28', only the paint in the paint chamber 2 is heated, heat diffusion is reduced, making heat management easier and reducing energy loss for heating. Note that if the material of the main body 5 is PPS resin, or the material of the nozzle plate 10 is ceramic, the insulating sheets may not be provided.

[0044] As the paint passes from the paint chamber 2 through the paint channel 32 in the discharge nozzle 11, heat is transferred from the discharged paint to the main body 5. However, since the paint passes through the discharge nozzle 11 at a speed of approximately 10 meters per second, there is little heat diffusion, the paint temperature does not drop significantly, the viscosity does not change drastically, and the discharge volume remains stable.

[0045] The insulating sheets 28 and 28' are preferably made of PTFE (Teflon®). PTFE sheets have a thermal conductivity of approximately 0.23 W / (m / K) and a volume resistivity of approximately >10^18 Ω·cm. However, the material of the insulating sheets 28 and 28' is not limited to these; any material that does not conduct heat or electricity poorly is acceptable.

[0046] Next, the material of the nozzle plate 10 will be described. It is preferable to use a material with a thermal conductivity of 20 W / (m / K) or less for the nozzle plate 10. The material of the nozzle plate 10 may be zirconia or austenitic stainless steel (SUS304). The thermal conductivity of austenitic stainless steel (SUS304) is approximately 16 W / (m / K).

[0047] If conductive austenitic stainless steel (SUS304) is used for the nozzle plate 10, there is a risk of current flowing through the nozzle plate 10 because electricity is also conducted through the heating element 12. For this reason, an insulating sheet 28' is necessary. By using a material with low thermal conductivity in this way, only the paint in the paint chamber 2 is heated, and heat diffusion is reduced, making heat management easier and reducing energy loss for heating. If the thermal conductivity is too high, the heating element 12 may need to be made larger, so it is preferable to have a low thermal conductivity as described above.

[0048] Next, the cleaning method 60, which is a cleaning method for the dot marking and printing device 1,1' of this embodiment, will be described in detail. As shown in Figure 5, the cleaning method 60 sequentially comprises a cleaning agent introduction step 61, a cleaning agent replenishment step 62, and a cleaning agent removal step 63.

[0049] First, the cleaning agent introduction process 61 will be described in detail. Figure 6(X) shows the state after the dot marking and printing device 1,1' has dispensed paint from the discharge nozzle 11 and performed dot printing. In Figure 6(X), the compressed air passage 3 and the compressed air flow path 30 are filled with air. From this state, the cleaning agent 41 is introduced through the cleaning agent inlet provided in the compressed air passage 3 (not shown), filling the compressed air passage 3 and the compressed air flow path 30. This state is shown in Figure 6(Y). The shaded area in Figure 6(Y) shows the state where the area is filled with the cleaning agent 41.

[0050] Next, the cleaning agent replenishment process 62 is shown. When dot marking and printing are not being performed in the dot marking and printing device 1,1', the cleaning agent replenishment process 62 is continued. In the cleaning agent replenishment process 62, the cleaning agent 41 is brought into contact with the tip 51 of the discharge nozzle as shown in Figure 6(Y), and the compressed air passage 3 and compressed air flow path 30 are kept filled with the cleaning agent 41.

[0051] At this time, the cleaning agent 41 evaporates over time. In particular, in the case of the dot marking and printing device 1,1' of this disclosure, the nozzle plate 10 may be heated over time by the heating element 12, even if it is made of a material with low thermal conductivity. Due to the rise in temperature of the nozzle plate 10, the temperature of the cleaning agent 41 in the compressed air passage 3 in contact with the nozzle plate 10 also rises, and a small amount of the cleaning agent 41 evaporates. In the cleaning agent replenishment step 62, the amount of cleaning agent 41 that has evaporated is continuously replenished to keep the compressed air passage 3 and the compressed air flow path 30 filled with cleaning agent 41.

[0052] In the detergent replenishment step 62, the detergent 41 may be continuously replenished, or it may be replenished at regular intervals, as long as an amount sufficient to keep the compressed air passage 3 and the compressed air flow path 30 filled with detergent is sufficient. To maintain this state, the compressed air flow path 30 and the compressed air outlet 52 of the dot marking and printing devices 1 and 1' are configured to be narrow, so that a surface tension phenomenon of the detergent 41 occurs at the compressed air outlet 52. For this reason, it is preferable that the compressed air flow path 30 and the compressed air outlet 52 are configured to be narrow enough that a surface tension phenomenon of the detergent 41 occurs at the compressed air outlet 52. In addition, in the detergent replenishment step 62, it is sufficient to prevent the discharge nozzle tip 51 from drying out, so it is not necessary to keep the entire compressed air passage 3 and the compressed air flow path 30 filled with detergent 41, but rather to replenish an amount sufficient to maintain contact between the detergent 41 and the discharge nozzle tip 51.

[0053] In the cleaning agent replenishment step 62, by maintaining the cleaning agent 41 in contact with the tip 51 of the discharge nozzle as shown in Figure 6(Y), it is possible to prevent the tip 51 of the discharge nozzle from drying out. If the tip 51 of the discharge nozzle dries out, the paint will solidify, leading to irregularities in dot markings and dot printing. Therefore, it is preferable to perform the cleaning agent replenishment step 62.

[0054] Next, the cleaning agent removal process 63 will be described in detail. The cleaning agent removal process 63 is performed immediately before the dot marking and printing devices 1,1' move on to the printing process, which involves dot marking and dot printing. In the cleaning agent removal process 63, the system transitions from the state shown in Figure 6(Y) to the state shown in Figure 6(Z). That is, the cleaning agent 41 that filled the compressed air passage 3 and the compressed air flow path 30 is removed by the compressed air introduced from the compressed air inlet. Figure 6(Z) shows the state after the cleaning agent 41 has been removed.

[0055] The cleaning method 60 may include a spit spray step after the cleaning agent removal step 63. The spit spray step is a step of discharging the paint in the discharge nozzle 11 toward objects other than the object to be marked and printed. In the cleaning agent replenishment step 62, etc., the cleaning agent 41 may have mixed with the paint in the discharge nozzle 11. Also, the temperature of the paint in the discharge nozzle 11 may have decreased. For this reason, it is preferable to perform a spit spray step to fill the discharge nozzle 11 with paint from the heated paint chamber 2. [Examples]

[0056] Next, an example of the conditions of an actual embodiment of the present invention is shown for the dot marking and printing device 1'. In the embodiment, the device was configured as described herein, namely consisting of a main body 5, a nozzle plate 10, and a cleaning plate 40, and was characterized by the inclusion of a gas chamber 4, a heating element 12, and an insulating sheet 28.

[0057] In the comparative example, the gas chamber 4 was not provided, the vibration mechanism 24 was filled with paint, the heating element 12 was not provided, and therefore the insulating sheet 28 was not provided, and thus the features of the present disclosure were not present.

[0058] Dot-pattern printing tests were conducted in the examples and comparative examples. Dot-pattern printing was performed under the following conditions. The drying time of the paint after printing was then measured. Paints, solvent-based paints Paint pressure 0.3 MPa Paint discharge speed 5m / sec Compressed air pressure 0.6 MPa Paint discharge nozzle diameter: 0.2 mm Heating element wattage: Approximately 30W Environmental temperature 20℃ Paint temperature rise +40℃ Printing speed 1.5m / sec Nozzle plate material: Zirconia

[0059] In the example, the drying time of the paint was approximately 20 seconds. In the comparative example, the drying time of the paint was approximately 30 seconds. Furthermore, while some areas of dot-shaped printing were observed in the comparative example, dot-shaped printing was possible without distortion in the example. In other words, the example had a shorter drying time and prevented distortion of the dot-shaped printing. The table below shows the results, with ○ indicating good print quality and △ indicating uneven print quality.

[0060] [Table 1]

[0061] 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]

[0062] 1. Dot-shaped marking and printing device 2, Paint room 3. Compressed air passage 4. Gas chamber 5. Main unit 10. Nozzle plate 11. Discharge nozzle 12, heating element 13, Wall 14, hole 20 valve seats 21 Valve body 22 Discharge control valve 23 Movable Iron Core 24 Vibration mechanism 25 seats 26. Sealing sheet 27, gap 28,28', Insulating sheet 30 Compressed air passage 31 Wall 32 Paint flow path 40, Washing plate 41. Cleaning agent 51 Discharge nozzle tip 52 Compressed air outlet 60. Washing method 61. Cleaning agent introduction process 62. Detergent replenishment process 63. Detergent removal process

Claims

1. A dot marking and printing device comprising a paint chamber for containing paint, a movable iron core, a valve body, a valve seat, a discharge nozzle, a compressed air passage, and at least one compressed air flow path, wherein a spherical valve body provided at the tip of the movable iron core has an open state in which it moves away from the valve seat and discharges from the paint chamber, and a closed state in which the valve body presses against the valve seat and stops discharge from the paint chamber, and the device is capable of imprinting characters or figures with dots by alternately transitioning between the open state and the closed state while moving relative to the object to be printed, The paint chamber is equipped with a heating element, The heating element is configured to be energized by a power supply source. The aforementioned heating element is a component that generates heat due to electrical resistance, A dot marking and printing device characterized in that the heating element can heat the paint in the paint chamber and maintain it at a constant temperature.

2. The dot marking and printing device comprises a main body, a nozzle plate separate from the main body, and a cleaning plate. The compressed air passage is surrounded by the cleaning plate and the nozzle plate, The paint chamber is constructed by being surrounded by the main body and the nozzle plate. The nozzle plate is provided with the discharge nozzle and the valve seat. The heating element is held so as to be fixed between the main body and the nozzle plate. Furthermore, the dot marking and printing device according to claim 1 is characterized in that the heating element can be connected to a power supply located outside the main body and the nozzle plate.

3. The dot marking and printing device according to claim 2, characterized in that an insulating sheet is provided between the nozzle plate and the heating element, or between the main body and the heating element, at least one of the two.

4. The dot marking and printing device according to claims 2 to 3, characterized in that the main body is provided with a gas chamber that communicates with the paint chamber.

5. A method for cleaning a dot marking and printing device using the dot marking and printing device described in claim 2, A cleaning agent introduction step of introducing a cleaning agent into the compressed air passage, A cleaning agent replenishment step is performed by utilizing the surface tension phenomenon of the cleaning agent that occurs at the cleaning agent discharge port of the cleaning plate to maintain the cleaning agent within the cleaning plate, and continuously replenishing the amount of cleaning agent that has decreased due to evaporation as the cleaning agent evaporates over time. The system includes a cleaning agent removal step, which involves introducing compressed air into the compressed air passage provided between the nozzle plate and the cleaning plate to remove the cleaning agent from the compressed air passage and the compressed air flow path. A method for cleaning a dot-shaped marking and printing device, characterized in that the cleaning agent introduction step, the cleaning agent replenishment step, and the cleaning agent removal step are performed sequentially.

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