A printing device that prints characters or graphics

Abstract

To provide a printer which can suppress deformation of a valve seat and prevent disturbance of printing and marking, and prints energy saving letters or figures.SOLUTION: A printer 1 for printing letters or figures comprises a coating chamber 2, a spherical valve body 3, and multilayer valve seats 4, 104. The valve seats 4, 104 include an inner layer 11, and an outer layer 12, and the valve seat 104 further include an intermediate layer 14. The printer 1 for printing letters or figures further comprises a guide part 80 which so guides the valve body 3 as to surround the valve body 3.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a dot marking and printing device for printing characters 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, and has a double structure with a discharge nozzle suitable for dot 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 the 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-like liquid paint is intermittently discharged from the discharge nozzle. When the discharge control valve is opened and closed by the reciprocating motion of the movable iron core, the spherical valve body contacts the valve seat. At this time, the spherical valve body contacts the valve seat in a pressing manner and seals so as to separate the paint chamber and the discharge nozzle. In this case, in the above configuration, due to the deformation of the valve seat, the stroke, which is the moving distance during the reciprocating motion of the movable iron core, may change. As a result, there have been problems such as poor maintainability, difficulty in discharging paint when maintenance is not performed frequently, and disturbance in paint discharge.

[0003] For example, in Patent Document 1, a dot printing device is provided with a double-tube nozzle having a compressed air ejection port surrounding the ejection nozzle around it, and the ejection nozzle protrudes longer than the compressed air ejection port by a predetermined distance, so that the growth of tailing can be prevented without disturbing the fine particles of the ejected dot-shaped liquid paint. The dot printing device disclosed in Patent Document 1 is excellent in that it can prevent the growth of tailing. However, the valve seat uses a conventional single-layer structure. For this reason, there are problems that the stroke changes during use, the ejection of the paint is disturbed, and thus maintenance inside the dot printing device is required, and these problems have not been solved.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The present invention has been made in consideration of such points, and an object thereof is to provide a printing device that prints characters or figures with improved maintainability by reducing the deformation of a valve seat that is frequently pressed by a valve body during dot printing, keeping the stroke constant for a longer period of time.

Means for Solving the Problems

[0006] Therefore, the present invention is a printing device for printing characters or figures, which comprises a paint chamber, a movable iron core, a valve body, a valve seat, and a discharge nozzle. The spherical valve body provided at the tip of the movable iron core is separated from the valve seat to form an open state in which paint is discharged from the paint chamber, and a closed state in which the valve body presses the valve seat to stop the discharge from the paint chamber. Further, by alternately shifting between the open state and the closed state while relatively moving with respect to the object to be printed, it is possible to print characters or figures by dots. In the printing device for printing characters or figures, the contact surface of the valve seat that contacts the valve body is substantially flat, or the contact surface is deformed by being pressed to form a substantially spherical belt shape. Further, the valve seat is provided with a cylindrical paint flow path that penetrates the center of the contact surface and is connected to the discharge nozzle. Furthermore, the valve seat is composed of two layers, an inner layer with a circular outer periphery surrounding the paint flow path and an outer layer that contacts and surrounds the outer peripheral surface of the inner layer. The boundary forming the paint flow path and the boundary between the inner layer and the outer layer is substantially concentric when viewed from the contact surface side, and the outer layer is formed harder than the inner layer.

[0007] Also, in the present invention, one or more intermediate layers are further provided between the inner layer and the outer layer, and each boundary between the inner layer and one or more of the intermediate layers and the outer layer and each boundary between the plurality of intermediate layers are all substantially concentric.

[0008] Also, the present invention is characterized in that a guide portion formed in a cylindrical shape is provided around the valve body to guide the operation of alternately repeating the open state and the closed state of the valve body.

[0009] Furthermore, in the present invention, the hardness of the inner peripheral portion of the valve seat is 40 or more and 70 or less in Shore hardness type A, and the hardness of the outer peripheral portion of the valve seat is 50 or more and 90 or less in Shore hardness type D.

Advantages of the Invention

[0010] The present invention relates to a printing device for printing characters or figures, which includes a paint chamber, a movable iron core, a valve body, a valve seat, and a discharge nozzle. A spherical valve body provided at the tip of the movable iron core has an open state in which it is separated from the valve seat and discharges paint from the paint chamber, and a closed state in which the valve body presses the valve seat to stop the discharge from the paint chamber. Further, in the printing device for printing characters or figures capable of printing characters or figures by dots by alternately shifting between the open state and the closed state while relatively moving with respect to the object to be printed, the contact surface of the valve seat that contacts the valve body is substantially flat, or the contact surface is pressed and deformed to form a substantially spherical belt shape. The valve seat also has a cylindrical paint flow path formed by penetrating the center of the contact surface and connecting to the discharge nozzle. Furthermore, the valve seat is composed of two layers, an inner layer with a circular outer periphery surrounding the paint flow path and an outer layer contacting and surrounding the outer peripheral surface of the inner layer. The boundary forming the boundary between the paint flow path, the inner layer, and the outer layer is substantially concentric when viewed from the contact surface side, and the outer layer is formed harder than the inner layer. Therefore, the valve seat that is frequently pressed by the valve body during dot printing can be less deformed by the pressing, the stroke can be kept constant for a longer time, and a printing device for printing characters or figures with improved maintainability can be obtained.

[0011] Further, in the present invention, one or more intermediate layers are further provided between the inner layer and the outer layer, and each boundary between the inner layer, one or more intermediate layers, and the outer layer and each boundary between the plurality of intermediate layers are all substantially concentric. Therefore, it is possible to prevent the deviation of the stroke trajectory of the valve body that frequently presses the valve seat during dot printing, and a printing device that prevents printing irregularities can be obtained.

[0012] Further, the present invention is characterized in that a guide portion formed in a cylindrical shape is provided around the valve body to guide the operation of alternately repeating the open state and the closed state of the valve body. Therefore, it is possible to prevent the deviation of the stroke trajectory of the valve body that frequently presses the valve seat during dot printing, and a printing device for printing characters or figures that prevents printing irregularities can be obtained.

[0013] Furthermore, in the present invention, the hardness of the inner peripheral portion of the valve seat is 40 or more and 70 or less in the durometer type A, and the hardness of the outer peripheral portion of the valve seat is 50 or more and 90 or less in the durometer type D. Therefore, the valve seat that is frequently pressed by the valve element during dot printing can reduce the deformation caused by the pressing, keep the stroke constant for a longer time, and can be used as a printing device for printing characters or figures with improved maintainability.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, the details of the embodiments of the present invention will be described with reference to the drawings. First, the printing device 1 for printing characters or graphics according to the present embodiment will be described. FIG. 1 is a schematic cross-sectional view showing an example of the printing device 1 for printing characters or graphics according to the present embodiment. For the sake of explanation, it is shown in a concentrated manner in the vicinity of the paint chamber 2. FIG. 2 is a schematic cross-sectional view showing a printing device 101 for printing characters or graphics provided with a guide portion 80, which is another example according to the present embodiment of FIG. 1. FIG. 2 is also shown in a concentrated manner in the vicinity of the paint chamber 2 for the sake of explanation. (X) shows the state when the valve body 3 is in the closed state, and (Y) shows the state when the valve body 3 is in the open state. FIG. 3 is a perspective view of the dot marking and the printing device 1 of FIG. 1, and is an explanatory view in which a part is cut away to expose the internal cross-section. FIG. 4(X) is a cross-sectional view of the valve seat 4 when the valve body is in the open state, and (Y) is a cross-sectional view of the valve seat 4 when the valve body is in the closed state. FIG. 5 is a cross-sectional view of the valve seat 104 when a three-layer valve seat 104 is used instead of the two-layer valve seat 4 in the printing devices 1 and 101 for printing characters or graphics as another example of the embodiment according to the present invention, where (X) is a cross-sectional view of the valve seat 104 when the valve body is in the open state, and (Y) is a cross-sectional view of the valve seat 104 when the valve body is in the closed state. FIG. 6(X) shows the cross-sectional view of the valve seat 4, and (Y) shows the cross-sectional view and the top view of the valve seat 104, respectively. FIG. 7 is a schematic cross-sectional view showing the vicinity of the compressed air flow path 30, which is a passage for compressed air for atomizing the paint discharged from the discharge nozzle 18 of the printing devices 1 and 101 for printing characters or graphics according to the present embodiment shown in FIGS. 1 and 2. FIG. 8 is a perspective view of a part of a printing system 102 for printing characters or graphics, in which a plurality of printing devices 1 for printing characters or graphics according to the present embodiment of FIG. 1 are provided, with the interior cross-section exposed by cutting away a portion thereof. In the present disclosure, for the sake of convenience of explanation, when simply referring to the upper side only, it refers to the upper side in FIGS. 1, 2, 4, and 5. The same applies to other directions based on the upper side.

[0016] First, while showing FIG. 1, the printing device 1 for printing characters or figures according to this embodiment will be described. The printing device 1 for printing characters or figures includes a vibration mechanism 24 and a paint chamber 2, and includes a movable iron core 23, a valve body 3 and a valve seat 4 or alternatively a valve seat 104 in the paint chamber 2, and further includes a discharge nozzle 18 and a compressed air passage 15. The lower side of the compressed air passage 15 is omitted in FIG. 1 and will be described when FIG. 7 is shown.

[0017] First, with reference to FIG. 1, the structure of the printing device 1 for printing characters or figures will be described in detail. First, the paint chamber 2 is provided to pump the paint into the paint flow path 7 provided inside the discharge nozzle 18, and includes a valve body 3 and a valve seat 4 or 104 for controlling the pumping. In FIG. 1, it is shown as the valve seat 4, but this part may be replaced with the valve seat 104. The same applies to FIGS. 2, 3, and 8. The paint chamber 2 is filled with paint used for discharging through the discharge nozzle 18 for dot printing. Between the paint chamber 2 and the paint flow path 7 to be described later, in the closed state of FIG. 1, it is sealed and blocked by the spherical valve body 3. The movable iron core 23 is rod-shaped, with one end fixed to the vibration mechanism 24, and the valve body 3 is fixed to the tip of the other end. The valve body 3 in the closed state presses the valve seats 4 and 104 in the paint chamber 2 to seal the paint in the paint chamber 2 so that it does not leak. It is preferable to use an elastic material such as rubber or resin for the valve seats 4 and 104. In the center of the valve seats 4 and 104, a paint flow path 7 is provided so as to penetrate the valve seats 4 and 104 vertically. The paint flow path 7 is formed by connecting to the inside of the discharge nozzle 18. Specifically, first, the paint flow path 7 penetrates the central part of the valve seats 4 and 104. Then, the paint flow path 7, which is a pipe passing through the valve seats 4 and 104, is formed by connecting to the inside of the discharge nozzle 18. The pipe inside the discharge nozzle 18 is also included in the paint flow path 7. However, the inlet of the paint flow path 7 on the paint chamber 2 side of the valve seats 4 and 104 can be opened and closed by the valve body 3. More specifically, the valve body 3 is provided so that it can be in a closed state by pressing the valve seats 4 and 104 so as to block the inlet of the paint flow path 7 of the valve seats 4 and 104, and the inlet of the paint flow path 7 can be in an open state by moving away from the inlet of the paint flow path 7. The discharge nozzle 18 is surrounded by a compressed air flow path 30 provided for atomization as shown in FIG. 7 on the lower side.

[0018] Next, a printing device 101 that prints characters or graphics while showing FIGS. 2(X) and 2(Y) will be described. FIG. 2(X) is a cross-sectional view of the printing device 101 that prints characters or graphics when the valve body 3 is in a closed state, and (Y) is a cross-sectional view when the valve body 3 is in an open state. First, the configuration of the printing device 101 that prints characters or graphics will be described. The printing device 101 that prints characters or graphics shown in FIG. 1 is the same as the printing device 1 that prints characters or graphics except that a guide portion 80 is provided. The guide portion 80 is provided to play a role of guiding the valve body 3 when it reciprocates up and down in FIG. 2. Therefore, it is provided so as to surround the spherical valve body 3 in a cylindrical shape and the distance between the guide portion 80 and the peripheral surface of the valve body 3 is equidistant over the entire circumference during the reciprocating motion. In both FIGS. 2(X) and 2(Y), the shortest distance between the guide portion 80 and the peripheral surface of the valve body 3 is equidistant. By providing the guide portion 80, even when the valve body 3 makes a faster reciprocating motion, it is possible to prevent the position where the valve body 3 contacts the valve sheets 4 and 104 from shifting, which is preferable.

[0019] Next, while showing FIGS. 2(X) and 2(Y), the reciprocating motion of the valve body 3 will be described in detail. The valve body 3 connected to the vibration mechanism 24 via the movable iron core 23 reciprocates up and down in FIG. 2 due to the operation of the vibration mechanism 24. The state of moving downward in FIG. 2(X) is shown, and it is assumed that the valve body 3 is in a closed state. The state of moving upward in FIG. 2(Y) is shown, and it is assumed that the valve body 3 is in an open state. The printing device 101 that prints characters or graphics circulates a certain amount of paint from the paint chamber 2 to the paint flow path 7 by repeatedly opening and closing the valve body 3, thereby performing dot printing. This reciprocating motion that alternately shifts between the open state and the closed state is also performed in the same manner for the printing device 1.

[0020] Next, while showing FIG. 3, the relationship between the valve body 3 and the valve seat 4 or 104 will be described. FIG. 3 is an explanatory view in which a part of the printing device 1 for printing characters or figures is cut out for explanation to expose the internal cross section, but it shows the same closed state as the printing device 101 for printing characters or figures in FIG. 2(X). When performing dot printing, as shown in FIG. 3, the valve seats 4, 104 are pressed downward against the spherical valve body 3. By the reciprocating motion, the valve seat becomes the state of FIG. 2(Y), and then a high-speed reciprocating motion is performed so as to become the state as shown in FIGS. 2(X) to 3. For this reason, with a conventional valve seat, it will be greatly deformed every time the number of times is repeated. Here, if the valve seat 4 or 104 is greatly deformed, the stroke, which is the distance traveled when the valve body 3 shifts from the open state to the closed state, will become longer or shorter or change. Then, the paint may not be discharged. The present invention has been made in view of this point.

[0021] When the printing devices 1, 101 for printing characters or figures are not used at all, the contact surfaces 13 of the valve seats 4, 104 of the present invention are formed in a substantially planar shape, but the valve seats 4, 104 may be recessed due to initial operations such as inspection. For this reason, the contact surfaces 13 of the valve seats 4, 104 of the present invention are formed in a substantially spherical belt shape by being deformed by being pressed while being substantially planar or having been substantially planar. Note that it is preferably substantially planar at the stage before being pressed from the viewpoint of maintaining the repulsive force.

[0022] Also, when the valve seats 4, 104 are blocked by the paint chamber 2 and the valve body 3, they are pressed by the valve body 3. At this time, in order to perform sufficient sealing, if the valve seat 4 is, for example, a conventional single-layer valve seat, it is necessary to have a certain degree of flexibility. However, when trying to seal sufficiently with flexibility, the inlet on the contact surface 13 of the paint flow path 7 is displaced from the center of the contact surface of the valve seat, and the positioning accuracy by the valve seat when the valve body 3 is in the closed state is reduced. Therefore, due to the displacement when the valve body 3 is in the closed state, there is a possibility that dot printing will be disturbed, and there is also a possibility that disturbance will occur in the direction of the stroke.

[0023] Next, while showing FIGS. 4 and 5, the valve sheets 4 and 104 used in the printing devices 1 and 101 for printing characters or figures according to the present invention will be described in detail. FIG. 4 shows an inner layer 11 provided on the valve sheet 4 so as to surround the paint flow path 7, and an outer layer 12 is further provided so as to surround the inner layer 11. The inner layer 11 and the outer layer 12 may be formed by injection molding the valve sheet 4 by a coextrusion method or the like. The inner layer 11 and the outer layer 12 are provided so as to adhere to each other.

[0024] FIG. 4(X) shows a cross-sectional view of the valve sheet 4 when the valve body 3 shown in FIG. 2(Y) is in the open state. At this time, the valve sheet 4 is in a completely unused state without performing an initial operation or the like, and is not pressed by the valve body 3. Also, what is shown by the broken line in FIG. 4(X) is a state of the open state where the valve body 3 does not contact the contact surface 13 when the contact surface 13 is deformed due to being pressed by the valve body 3 during an initial operation or the like. FIG. 4(Y) shows the valve sheet 4 when the valve body 3 shown in FIG. 2(X) is in the closed state. At this time, the valve sheet 4 is in a state of being recessed by being pressed by the valve body 3.

[0025] FIG. 5(X) shows the valve sheet 104 when the valve body 3 shown in FIG. 2(Y) is in the open state. At this time, although the initial operation of the valve sheet 104 has been completed, it is not pressed by the valve body 3. Before the initial operation such as inspection and trial operation is completed, the contact surface 13 is also substantially flat in FIG. 5. FIG. 5(Y) shows the valve sheet 104 when the valve body 3 shown in FIG. 2(X) is in the closed state. At this time, the valve sheet 104 is in a state of being recessed by being pressed by the valve body 3.

[0026] The distance α shown in Fig. 4(Y) represents the distance between the changed contact surface 13 when the valve seat 4 pressed by the valve element undergoes the maximum change and the contact surface in Fig. 4(X) where there is no change. This indicates the degree of change in the valve seat 4. Also, the distance β shown in Fig. 5(Y) represents the distance between the changed contact surface 13 when the valve seat 104 pressed by the valve element undergoes the maximum change and the contact surface 13 in Fig. 5(X) where there is no change. This indicates the degree of change in the valve seat 104.

[0027] In both Fig. 4(Y) and Fig. 5(Y), the valve seats 4 and 104 are in a concave state, but the distance of β is shorter than that of α, which is preferable from the perspective of energy conservation.

[0028] As described above, the valve seat 4 is formed of rubber, resin, etc. However, the inner layer 11 shown in Fig. 4(X)(Y) is softer than the outer layer 12, and the outer layer 12 is formed of a harder material than the inner layer 11. When the valve element 3 transitions from the open state as shown in Fig. 2(Y) to the closed state as shown in Fig. 2(X), the valve element 3 is formed to first contact the inner layer 11 of the valve seat 4. Then it is formed to contact the outer layer 12.

[0029] Also, as described above, at the position where the valve element 3 presses the valve seat 4 to the lowermost side as shown in Fig. 2(X), it has changed by the distance of α as shown in Fig. 4(Y), and this is the part that changes the most when the valve seat 4 is in the closed state. The inner layer 11 has a width approximately half that of the outer layer 12 at the contact surface 13, and the boundary line 90, which is its boundary, is preferably linear in the cross-sectional view of Fig. 4(X) so as to be perpendicular to the planar contact surface 13. The same applies to the boundaries between the layers when there are a plurality of the first boundary line 91, the second boundary line 92, and other intermediate layers 14. By forming it in this way, when the valve element 3 changes from the open state to the closed state, the repulsive forces of the valve seats 4 and 104 are evenly applied to the valve element 3, and displacement can be prevented.

[0030] The valve seat 104 is also formed of rubber, resin, or the like as described above. However, the inner layer 11 shown in FIGS. 4(X) and 4(Y) is softer than the outer layer 12, and the outer layer 12 is formed of a harder material than the inner layer 11. An intermediate layer 14 is provided between the inner layer 11 and the outer layer 12. The intermediate layer 14 is formed harder than the inner layer 11 and softer than the outer layer 12. Also, a plurality of intermediate layers 14 may be provided between the inner layer 11 and the outer layer 12. In this case, the intermediate layer closer to the inner layer 11 is softer, the intermediate layer closer to the outer layer 12 is harder, and it is formed harder than the inner layer 11 and softer than the outer layer 12.

[0031] While showing FIG. 4, the relationship between the valve body 3 and the valve seats 4 and 104 will be described in detail. When the valve body 3 transitions from the open state as shown in FIG. 2(Y) to the closed state as shown in FIG. 2(X), the valve body 3 is first formed to contact the inner layer 11 of the valve seat 4. Thereafter, it is formed to contact the outer layer 12. Also, as described above, at the position where the valve body 3 has pushed the valve seat 4 to the lowermost side as shown in FIG. 2(X), as shown in FIG. 4(Y), it has changed by a distance α, and this is the portion that has changed the most when the valve seat 4 is in the closed state.

[0032] Next, while showing FIG. 5, the valve seat 104 will be described in detail. FIG. 5(X) shows a cross-sectional view of the valve seat 104. The contact surface 13 of the valve seat 104 is flat when it is completely unused, but it is recessed as shown in FIG. 5(X) due to inspection, initial operation, or the like. When the printing devices 1 and 101 for printing characters or figures are in the closed state as shown in FIG. 2(X), the contact surface 13 of the valve seat 104 as shown in FIG. 5(Y) is further recessed. The valve seat 104 is provided with a paint flow path 7 at the center, and the inner layer 11, the intermediate layer 14, and the outer layer 12 surround it in order. The inner layer 11 and the intermediate layer 14, and the intermediate layer 14 and the outer layer 12 are adhered at the first boundary line 91 and the second boundary line 92, respectively. Existing techniques for lamination may be used for the adhesion.

[0033] Next, while showing FIG. 6, the positional relationship between the valve body 3 and the valve seat will be described in more detail. The upper diagram in FIG. 6(X) is a cross-sectional view of the valve seat similar to FIG. 4(X), and the lower diagram is a view of the valve seat seen from the contact surface 13 side. The valve body 3 is shown by a dotted line. Other configurations are omitted for the sake of explanation. When the valve body 3 transitions from the open state to the closed state, first, as shown in the upper diagram of FIG. 6(X), it comes into contact with the paint flow path 7. Next, it contacts and presses the inner layer 11. When it contacts the outer layer 12 (not shown), the order of pressing is the last. Also, as shown in the lower diagram of FIG. 6(X), the edge of the paint flow path 7, the boundary line 90 which is the boundary between the inner layer 11 and the outer layer 12, and the outer edge of the valve seat 4 are all formed in concentric circles centered on the origin O. Since it is formed in this way, when the valve body 3 presses the valve seat 4, it is suitable that force is evenly applied to the valve body 3.

[0034] Also, the inner layer 11 shown in FIG. 6(X) is softer than the outer layer 12, and the two are adhered. So, when the valve body 3 transitions from the open state to the closed state, first, in the inner layer 11, the momentum of the valve body 3 is weakened to receive the valve body 3, and then, with respect to the force applied downward on the contact surface 13 of the inner layer 11 so that the contact surface 13 of the inner layer 11 is recessed, in the outer layer 12, a force to push back in the opposite direction is applied. By configuring the valve seat 4 to have a repulsive force against the pressing of the valve body 3, the stroke which is the moving distance of the valve body 3 can be maintained. To ensure this repulsive force, it is more preferable that the hardness of the outer layer 12 is 50 or more and 90 or less in measurement by the durometer type D. This is the same in the relationship between the inner layer 11 and the intermediate layer 14, and the intermediate layer 14 and the outer layer 12 of the valve seat 104 shown in FIG. 6(Y).

[0035] Further, since the hardness of the inner layer 11 is 40 or more and 70 or less as measured by a durometer type A and is configured to be sufficiently soft, the sealing performance is improved as compared with the case where the valve seat 104 is a single layer and the whole is configured to be harder. When the sealing performance is improved, sufficient sealing performance can be maintained even with a weak pressing force of the valve body. Therefore, when shifting the valve body 3 from the closed state to the open state, the stroke, which is the distance for lifting the valve body 3, may be designed to be shorter. By configuring in this way, the pressing force of the valve body 3 against the valve seat 104 can be weakened, so that the vibration energy is reduced and the energy consumption is low, and the energy-saving type printing devices 1 and 101 can be achieved.

[0036] Next, the positional relationship between the valve seat 104 and the valve body 3 will be described in detail with reference to FIG. 6(Y). The upper diagram of FIG. 6(Y) is a cross-sectional view of the valve seat similar to FIG. 5(X), and the lower diagram of FIG. 6(Y) is a view of the valve seat seen from the contact surface 13 side. The valve body 3 is indicated by a dotted line. Other configurations are omitted for the sake of explanation. When the valve body 3 shifts from the open state to the closed state, first, as shown in the upper diagram of FIG. 6(Y), the lower end of the valve body 3 descends toward the valve seat 104 to the position V. When it descends to the position V, the valve body 3 comes into contact with the paint flow path 7. Next, it contacts the inner layer 11 and presses it. Next, it comes into contact with the intermediate layer 14 and presses it. In FIG. 6(Y), the valve body 3 at this time is also indicated by a dotted line as in the case of reaching the position W. Although not shown, when contacting the outer layer 12, the order of being pressed is the last.

[0037] Furthermore, when the intermediate layer 14 is composed of multiple layers, the valve body 3 contacts each layer of the intermediate layer 14 in order from the inner side, which is closer to the paint flow path 7. Also, as shown in the lower figure of Fig. 6(Y), the edge of the paint flow path 7, the first boundary line 91 which is the boundary between the inner layer 11 and the intermediate layer 14, when there are multiple intermediate layers 14, one or more boundary lines which are their boundaries, the second boundary line 92 which is the boundary between the intermediate layer 14 and the outer layer 12, and the outer edge of the valve seat 4 are all formed concentrically with the origin O as the center. Since it is formed in this way, when the valve body 3 presses the valve seat 4, it is suitable that the force is evenly applied to the valve body 3.

[0038] The materials of the valve seats 4 and 104 can be widely used as long as they are rubbers such as natural rubber, isoprene rubber, and styrene-butadiene rubber. Also, silicon or resin can be used.

[0039] In this way, although the materials of the valve seats 4 and 104 are rubber, resin, etc., their hardness is formed so as to increase in the order of the inner layer 11, the intermediate layer 14, and the outer layer 12. Therefore, when the valve body 3 moves from the open state to the closed state, first, the inner layer 11 weakens the momentum of the valve body 3 and receives the valve body 3. Next, the valve body 3 comes into contact with the intermediate layer 14, further weakening the momentum. After that, in the outer layer 12, a force is applied to the contact surface 13 of the inner layer 11 so that the contact surface 13 of the inner layer 11 is deformed in a concave shape, and conversely, a force to push it back is applied.

[0040] By configuring the valve seat 104 shown in Fig. 6(Y) to have a repulsive force against the pressing of the valve body 3, the stroke, which is the moving distance of the valve body 3, can be maintained. To ensure this repulsive force, it is more preferable that the hardness of the outer layer 12 is 50 or more and 90 or less in measurement by the durometer type D. Also, since the hardness of the inner layer 11 is 40 or more and 70 or less in measurement by the durometer type A and is configured to be sufficiently soft, the sealing performance is better than when the valve seat 104 is a single layer and the whole is configured to be harder. When the sealing performance is improved, sufficient sealing performance can be maintained even if the pressing force of the valve body is weak.

[0041] Therefore, when shifting the valve body 3 from the closed state to the open state, it is possible to design a shorter stroke, which is the distance to lift the valve body 3. For this reason, an energy-saving type printing device 1, 101 with low energy consumption can be obtained. The above description is equally applicable when there are a plurality of intermediate layers 14 and there is an intermediate layer that does not contact the valve body 3 in the closed state, or conversely when the valve body 3 also contacts the outer layer 12. By adopting the configuration having the intermediate layer 14, the sealing performance can be more easily ensured compared to the case of the valve seat 4, and the hardness of the outer layer 12 can also be made harder. Therefore, the positioning accuracy of the valve seat 104 with respect to the valve body 3 can be further improved, which is more preferable.

[0042] Next, the compressed air passage 15 and the compressed air flow path 30 of the printing device 1 shown in FIG. 7 will be described in detail. The compressed air passage 15 is a passage for introducing compressed air into the nozzle plate 16 from an air compressor or the like, which is a compressed air supply source not shown in the figure. The compressed air passage 15 communicates with the compressed air flow paths 30 provided in the same number as the discharge nozzles 18, and the compressed air has a structure of flowing from the compressed air passage 15 into the compressed air flow paths 30. Also, the method of forming the compressed air passage 15 may be such that the nozzle plate 16 is fitted into the discharge nozzle 18, and the gap formed therebetween is used as the compressed air passage 15. In this case, due to the need to ensure the airtightness of the compressed air passage 15 formed by the fitting, a sheet 25 shown by a dotted line in FIG. 1 having the function of a packing is attached so as to be in close contact with the wall on the paint chamber 2 side not shown.

[0043] The compressed air flow path 30 is composed of an atomizing section 40, a discharge nozzle holding section 41, and an air introduction section 42. Further, the compressed air flow path 30 is surrounded by the atomizing nozzle 17 and surrounds the discharge nozzle 18. Thus, the atomizing nozzle 17 has a double structure. Although not shown in FIG. 3, the air introduction section 42 in FIG. 7 is an introduction portion that introduces compressed air from the compressed air passage 15 into the compressed air flow path 30. The air introduction section 42 is preferably tubular to reduce pipeline resistance, and may not be provided depending on the design requirements of the discharge nozzle 18.

[0044] Next, the discharge nozzle holding section 41 will be described. As will be described in detail later, as shown by the dotted line in FIG. 1, the discharge nozzle holding section 41 is provided in a tapered mortar shape with respect to the flow path direction of the compressed air, and holds the discharge nozzle 18 at approximately the center of the compressed air flow path 30. Further, the discharge nozzle holding section 41 includes a plurality of protrusions 33. As shown in FIG. 1, by forming the discharge nozzle holding section 41 obliquely with respect to the flow path direction of the compressed air, the pipeline resistance can be reduced, leading to a reduction in the consumption of compressed air, which is preferable.

[0045] Next, the atomizing section 40 will be described. The atomizing section 40 is a part for the discharge nozzle 18 to discharge and atomize the paint with compressed air. The atomizing section 40 preferably has a smaller cross-sectional area than other parts of the compressed air flow path 30. 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 18, the paint droplets can be atomized with less compressed air, which is preferable.

[0046] Next, the wall portion 31, which is a wall that blocks the two compressed air flow paths 30 from each other, will be described. Conventionally, the wall portion 31 was provided on both sides of each compressed air flow path 30. However, with such a configuration, two walls 31 were provided between the adjacent compressed air flow paths 30, resulting in wasted space. By providing the wall portion 31 as a single wall that blocks the two compressed air flow paths 30 on the nozzle plate 16, the width of the pitch between the discharge nozzles 18 can be significantly reduced compared to the conventional case.

[0047] The nozzle plate 16 will be described in further detail. The compressed air passage 15 has a hole for introducing air from the outside by an air compressor (not shown) or the like. As shown in FIG. 7, it is preferable that the compressed air passage 15 communicates with a plurality of compressed air flow paths 30. However, it can also be configured not to communicate as shown in FIG. 8.

[0048] The compressed air passage 15 is connected to the compressed air introduction part 42 of the compressed air flow path 30 in order from the lower side of FIG. 7, and further connected to the compressed air introduction part 42 of the compressed air flow path 30 which is another spray nozzle. With this configuration in which the compressed air passage 15 communicates with a plurality of compressed air flow paths 30, compressed air can be supplied to a large number of compressed air flow paths 30 at once from one compressed air supply source.

[0049] Due to the nature of the printing device 1, if the position of the discharge nozzle 18 changes or shakes from the center of the compressed air flow path 30, atomization will not be properly performed and the printing performance will deteriorate. Therefore, it is necessary to hold it firmly. For this reason, it is preferable that the number of protrusions 33 for holding the discharge nozzle 18 is 3 or more and 8 or less.

[0050] The compressed air introduction part 42 may be omitted. In addition, since the required amount of compressed air can be reduced by forming the compressed air introduction part 42 with as little pressure loss as possible, the compressed air introduction part 42 is preferably cylindrical.

[0051] FIG. 8 shows a printing system 102 including a plurality of printing devices 1. Although the paint chambers 2 are shown separately in the figure, the paint chambers 2 may be connected to each other. The printing system 102 is configured to be able to print characters or figures with dots by moving the whole relative to the object to be printed.

Example

[0052] Next, an example of the conditions of the embodiment of the present invention actually performed in the dot marking and the printing device 1 will be shown. Example 1 had a configuration including a paint chamber 2, a movable iron core 23, a vibration device 24, a spherical valve body 3, a valve seat 4, and a guide portion 80 as shown in FIG. 2 of the present disclosure. Example 2 was the same as Example 1 in that it included a paint chamber 2, a movable iron core 23, a vibration device 24, a spherical valve body 3, and a guide portion 80, but had a configuration including a valve seat 104 instead of the valve seat 4.

[0053] In the comparative example, it was the same in that it included a paint chamber 2, a movable iron core 23, a vibration device 24, and a spherical valve body 3, but the portion corresponding to the valve seat 4 of the present disclosure was configured as a single-layer valve seat without an inner layer, an outer layer, etc. Then, tests were conducted under the following conditions.

[0054] [Durability Test] In Examples 1 and 2 and the comparative example, a dot printing test was conducted for 700 hours to confirm durability. Dot printing was performed under the following conditions. Then, the degree of disturbance of the dot printing and the amount of deformation of the valve seat were evaluated by sensory evaluation. Paint pressure 0.1 - 0.7 MPa Paint discharge speed 0.5 - 20 m / sec Paint discharge nozzle diameter 0.1 - 0.3 mm Printing speed 0.5 - 3 m / sec Dot pitch 3 - 5 mm

[0055] In both Examples 1 and 2, it was possible to prevent disturbance of the dot printing. However, in terms of durability, although the amount of deformation of the valve seat was less than that of the comparative example, in Example 2, the amount of deformation of the valve seat was particularly small and excellent. In the comparative example, disturbance of the printing was observed when about 200 hours had passed. Also, the amount of deformation of the valve seat was larger than that in Examples 1 and 2. Therefore, it can be said that the positioning accuracy was poor. This is presumably because the material of the valve seat was too soft compared to Examples 1 and 2.

[0056] The present disclosure can be suitably used for the purpose of printing or marking an inspected object to be printed. However, it is not limited to this, and it can be widely used in packages and certified parts that require dot-like marking and printing.

Explanation of Signs

[0057] 1, 101 Printing device for printing characters or figures 2 Paint chamber 3 Valve body 4, 104 Valve seat 7 Paint flow path 11 Inner layer 12 Outer layer 13 Contact surface 14 Intermediate layer 15 Compressed air passage 16 Nozzle plate 17 Atomizing nozzle 18 Discharge nozzle 23 Movable iron core 24 Vibration mechanism 25 Sheet 30 Compressed air flow path 31 Wall portion 33 Protrusion 40 Atomizing portion 41 Discharge nozzle holding portion 42 Compressed air introduction portion 80 Guide portion 102 Printing system

Claims

1. A printing device for printing characters or figures, comprising a paint chamber, a movable iron core, a valve body, a valve seat, and a discharge nozzle, wherein the spherical valve body provided at the tip of the movable iron core is separated from the valve seat and is in an open state for discharging from the paint chamber, and the valve body presses the valve seat to stop the discharge from the paint chamber. In the printing device for printing characters or figures that can print characters or figures by dots by alternately shifting between the open state and the closed state while relatively moving with respect to the object to be printed, the contact surface of the valve seat that contacts the valve body is substantially flat, or the contact surface is pressed and deformed to form a substantially spherical belt shape, and the valve seat penetrates the center of the contact surface and is formed with a cylindrical paint flow path connected to the discharge nozzle. Further, the valve seat is composed of two layers, an inner layer with a circular outer periphery surrounding the paint flow path and an outer layer contacting and surrounding the outer peripheral surface of the inner layer. The boundary forming the paint flow path and the boundary between the inner layer and the outer layer is substantially concentric as viewed from the contact surface side, and the outer layer is formed harder than the inner layer. A printing device for printing characters or figures.

2. One or more intermediate layers are further provided between the inner layer and the outer layer, and each boundary between the inner layer and one or more of the intermediate layers and the outer layer and each boundary between the plurality of intermediate layers are all substantially concentric. The printing device for printing characters or figures according to claim 1.

3. A printing device for printing characters or figures according to claims 1 to 2, further comprising a guide portion formed in a cylindrical shape around the valve body to guide the operation of alternately repeating the open state and the closed state of the valve body.

4. The hardness of the inner peripheral portion of the valve seat is 40 or more and 70 or less in Shore A durometer, and the hardness of the outer peripheral portion of the valve seat is 50 or more and 90 or less in Shore D durometer. The printing device for printing characters or figures according to claims 1 to 3.

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