JP2003080133A - Marking device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a marking device capable of always marking a stable dot even if the pressure of a liquid varies. SOLUTION: The marking device is equipped with a drive part (10) comprising a fixed iron core (11), a movable iron core (12) and a solenoid coil (13) and a marking head part 20 adjacent to the drive part in a longitudinal axis direction and the marking head part comprises the valve disc connected to the movable iron core through a connection rod (28), a valve housing (23) having a valve seat (30), the nozzle (32) extending from the nozzle inlet (31) of the valve seat along the longitudinal axis and the pressure liquid filling part (26) formed between the valve disc and the movable iron core. A guide part (25) to which the valve disc is fitted in a freely slidable manner so as to leave a gap is formed in the valve housing and the gap (P) between the guide part and the valve disc is minute so that the valve disc is brought in a valve seat closing direction by the force of the liquid flowing to the inlet of the nozzle at a high speed from the pressure liquid filling part through the gap of the guide part when the movable iron core is attracted by a solenoid and the valve disc is opened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compact and high speed marking device for ejecting paint, ink or the like.

[0002]

2. Description of the Related Art A marking device of this type is disclosed in Japanese Patent Laid-Open No. 2-1
It is described in Japanese Patent No. 31164. A vertical sectional view of this marking device is shown in FIG. This device includes a drive unit 100.
And a marking head unit 110. Drive unit 100
Is composed of a fixed iron core 101, a movable iron core 102 adjacent to the fixed iron core with a gap in the direction of the vertical axis, and a solenoid coil 103 around these iron cores. A marking head 110 is attached to an iron core holder 104 holding the drive unit 100 via a head holder 111. Inside the head holder 111, the movable iron core 10
A connecting rod 112 extends from 2, and a valve element 113 fixed to the tip of this connecting rod is seated on a valve seat 114. Inside the head holder 111, the valve body 11
The cylindrical space on the right side of 3 forms a pressure liquid filling section 117, and has a liquid supply hole 118 communicating with the pressure liquid filling section 117. The nozzle inlet at the center of the valve seat 114 communicates with the injection nozzle 115 that extends along the longitudinal axis.
A connecting rod 112 is provided between the valve body 113 and the movable iron core 102.
The small diameter side of the conical spring 116 is fixed and the large diameter side of the conical spring 116 is fixed to the iron core holder 104. Therefore, the nozzle inlet of the valve seat is closed by the valve body 113 which is constantly biased by the conical spring 116. When a current flows through the solenoid coil 103, the movable iron core 102 is attracted against the force of the conical spring 116 and the valve body 113 is pulled up to open the valve. As a result, the pressure liquid is ejected through the ejection nozzle 115.

However, when a current is passed through the solenoid coil 103 to attract the movable iron core 102, the movable iron core 102 hits the fixed iron core 101 to generate noise. In addition, the movable iron core 10 is restored by the restoring force of the conical spring.
2. Therefore, since the valve body 113 fixed to this returns to a fixed position, as the pressure of the liquid to be ejected fluctuates and increases, the discharge amount of the liquid increases and the pressure of the liquid decreases. The discharge amount of the liquid was reduced, and as a result, the diameter of the dot was changed, and the printing quality was degraded.

[0004]

DISCLOSURE OF THE INVENTION An object of the present invention is to provide a marking device for jetting paint, ink, etc., which is capable of always marking a stable dot even in an environment where the liquid pressure is likely to fluctuate. Is to provide.

[0005]

According to the present invention, the above-mentioned object is to form the valve body in a cylindrical shape and to form a cylindrical hole into which the valve body is slidably fitted with a clearance. A guide portion is formed, and a gap between the guide portion and the valve body is drawn from the pressure liquid filled portion to the guide portion when the movable iron core is attracted by the solenoid and the valve body connected to the movable iron core opens. The marking device is a minute gap in which the valve body is entrained in the direction of closing the valve seat by the force of the liquid flowing at a high speed through the gap to the nozzle inlet side.

The pressure loss between the valve body and the guide portion is
It is suitable that it is 0.3 to 3 times the pressure loss of the nozzle portion.

The minute gap in the guide portion has a nozzle diameter of
20 to 50 μm is suitable for 0.1 mm. The length of the guide portion is appropriately 1 to 20 mm when the nozzle length is 5 mm.

In addition to the conditions of the mechanical components described in claim 1, the energization time to the solenoid coil is 0.02 to
It is also an important element of the present invention to control the coil current so as to set a current value such that the movable iron core moves within a range where the movable iron core does not touch the fixed iron core when the time is set to 2.00 ms. As a result, the noise caused by the collision between the movable core and the fixed core is eliminated, and the movement amount of the movable core changes due to the change in the paint pressure.

Further, since the valve is closed by the flow rate of the pressure liquid flowing through the guide portion gap when the valve body is opened, the return spring is not essential, but if the original pressure of the liquid in the pressure liquid filling portion is high (0.5 It is also possible to provide a movable iron core return spring having a spring force weak enough to support the movable iron core along the connecting rod, for example, 10 g or more. Incidentally, the spring force of the conventional return spring was 120 g.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below with reference to the embodiments shown in the drawings.

FIG. 1 shows a vertical section of a paint marking apparatus according to the present invention. FIG. 2 is a schematic diagram showing the principle of the present invention.

The marking device according to the present invention comprises a drive unit 1.
0 and the marking head unit 20, and the driving unit 10
Is a fixed iron core 11, a movable iron core 12, a solenoid coil 1
3 and these are held by the iron core holder 14.

The marking head portion 20 is bolted to the iron core holder 14 by a head holder 21.
A valve housing 23 is fitted in the hole of the cylindrical portion 22 of the head holder 21, and a guide portion 25 into which the peripheral surface of the valve body 24 is fitted with a minute gap is provided in the valve housing 23. ing. The space between the valve element 24 and the movable iron core 12 forms a pressure paint filling portion 26, and the paint under pressure is supplied from the pressure paint supply hole 27. A spring 29 having a weak spring force of, for example, 10 g is provided in the space, the spring 29 having one end fixed to the connecting rod 28 and the other end fixed to the inner wall of the iron core holder 14.

A valve seat 30 is formed in the valve housing 23, and an injection nozzle 32 extends in a direction opposite to the iron core side through a nozzle inlet 31 at the center of the valve seat 30. The valve housing 23 is fixed to the head holder 21 with a bolt 34 via a collar 33.

The gap between the outer peripheral surface of the valve body 24 and the inner peripheral surface of the guide portion 25 is a minute gap. The minute gap is attracted to the movable iron core 12 by applying a current to the solenoid to open it. When valved, the valve body 24 connected to the movable iron core 12 via the connecting rod 28 causes the valve body 24 to be valved by the force of the pressure paint flowing from the pressure paint filling portion 26 to the gap between the valve body 24 and the guide portion 25 at high speed. It is a minute gap that is entrained in the direction in which the nozzle inlet 31 of the seat 30 is closed.

It is also possible to form the tip of the valve body 24 in a hemispherical shape and to form the valve seat 30 in a conical shape.

The operation of the marking device having the marking head portion 20 will be described.

The space between the valve body 24 and the movable iron core 12 is filled with the pressure paint pressure-fed from the paint supply port 27 as indicated by the arrow, and forms a pressure liquid filling portion 26. When a current is applied to the solenoid coil 13, the movable iron core 1
Since 2 is pulled up, the valve body 24 connected to this is also pulled up to open the valve. As a result, the nozzle inlet 3
1 is opened, and the paint in the pressure liquid filled portion 26 is filled with the valve element 24.
A small gap D between the outer peripheral surface of the guide and the guide portion 25, for example, 20
It flows through the gap of μm at a high flow rate, flows into the nozzle inlet 31, and is jetted through the nozzle 32. In this case, the paint discharge speed is determined by the paint pressure P1 applied to the nozzle inlet 31 (see FIG. 2). As described above, the valve body 24 is carried toward the nozzle inlet 31 in the direction of closing the valve by the force of the paint flowing through the valve body 24 and the guide portion gap D when the valve is opened. Iron core 1
2. Therefore, the force of closing the valve body 24 is balanced with the suction force of the solenoid to leave a constant nozzle gap (see FIG. 2) at the valve body 24, and hence the movable core 12 connected to the valve body 24.
Stops midway. As a result, the movable iron core 12 does not touch the fixed iron core 11, so that no noise is generated. When the electric current of the solenoid coil 13 is cut off, the attractive force is lost,
The valve body 24 closes the nozzle inlet 31 by the force of the paint flowing through the guide portion gap D.

Here, consider a case where the paint source pressure P0 fluctuates in a state where a current flows through the solenoid coil 13 to attract the movable iron core 12 and open the valve (since the movable range of the movable iron core is very small, Therefore, it is assumed that the attraction force of the solenoid does not change depending on the position of the movable iron core).

When the paint original pressure P0 increases, the flow velocity flowing through the gap between the guide portion 25 and the valve body 24 (hereinafter referred to as the guide portion gap D) also increases. Then, the force for closing the valve body 24 increases, so that the valve body 24 starts to close. However, as the valve body 24 is closed, the fluid resistance in the nozzle gap increases, and the flow velocity of the paint flowing in the guide gap becomes slower. If the suction force is considered to be constant, the nozzle inlet 3
When the pressure of 1 becomes P1, the guide part gap D again.
Because the force of closing the valve body 24 is balanced with the suction force of the solenoid by the flow velocity of, the valve body 24 does not move and the discharge speed of the paint does not change. Although it has been described that the pressure is balanced when the pressure at the nozzle inlet 31 becomes P1, this is for the following reason. Actually, it is the guide portion gap D that balances with the suction force of the solenoid.
Is the force due to the flow velocity of. However, since the flow rate of the paint flowing in the marking head portion is determined by the pressure of the nozzle inlet 31, the flow velocity of the guide portion gap D is also determined by the pressure of the nozzle inlet 31. Therefore, it means that the pressure P1 at the nozzle inlet and the suction force of the solenoid are eventually balanced.

Contrary to the case where the paint source pressure P0 decreases, the flow velocity in the guide portion gap D decreases, and the position of the valve element 24 rises from the nozzle inlet 31 to open the nozzle gap more. As a result, the paint pressure at the nozzle inlet increases. The paint discharge speed is kept constant by increasing the paint pressure at the nozzle inlet until it returns to the same pressure as P1.

As described above, by making the gap D between the guide portion and the valve body extremely small, feedback is applied to the position of the movable iron core, that is, the valve body, in response to the pressure fluctuation of the paint. Due to this effect, the paint pressure at the nozzle inlet is kept constant, so the paint discharge speed becomes constant,
Marking with a stable dot diameter can be performed. In addition to the mechanical conditions mentioned above, it is also important to limit the current value to the solenoid coil. That is, there is also a method of increasing the energizing time to the solenoid coil to make the suction force, but this method, because the force for pulling up the movable iron core changes too much due to the fluctuation of the paint pressure, the energizing time to the solenoid is relatively short, That is, the current value should be set so that the movable core moves within a range where it does not touch the fixed core when it is set to 0.02 to 2.00 ms.

FIG. 3 shows a discharge amount when the paint pressure fluctuates from 0.2 MPa to 1 MPa using a paint having a viscosity of 22 cP in a marking device according to the present invention having a nozzle diameter of 120 μm and a guide portion gap of 20 μm. It is a graph which shows the measured result. It can be seen that the discharge amount of the paint hardly changes even if the discharge pressure of the paint changes. In the conventional technique, it is necessary to keep the paint pressure constant because the dot diameter changes when the paint pressure changes. In the aerosol method in which paint is supplied by the pressure of gas, the pressure drops with use, so this cannot be used, and a pump has been used to pressurize the paint. However, in order to use the pump as a paint supply means, a pump and a device for controlling the pump are required, which hinders downsizing and cost reduction of the marking device. In the marking device of the present invention, since it is not necessary to keep the paint pressure constant, it is possible to adopt an aerosol method as the paint supply means, and it is possible to realize the downsizing and cost reduction of the marking device. In addition, in a normal marking device, the paint is circulated so that the pigment and the like in the paint do not settle and the nozzles for discharging the paint do not clog. When the aerosol type paint supply means is used, such paint circulation cannot be performed,
If the marking is stopped for a long time, the nozzle is likely to be clogged. Therefore, in this case, by looping a part of the paint pipe, the amount of paint settling inside the head can be reduced. As shown in FIG. 5, the aerosol paint can (41) is connected to the paint supply port of the marking device by a looped paint piping loop (42). The loop is preferably installed near the marking head portion.

[0024]

In the marking device of the present invention, when the cylindrical valve body connected to the movable iron core is pulled up from the nozzle inlet of the valve seat to open the valve by applying a current to the solenoid coil, the pressure liquid is filled from the pressure liquid filled portion. When the paint pressure fluctuates when the paint pressure fluctuates, it is configured so as to be carried in the direction of closing the valve body by the force of the pressure liquid that flows at high speed through the minute gap between the valve body and the guide part around the valve body. If it increases, the paint flow velocity in the gap of the guide portion increases, so that the force to close the movable iron core and hence the valve body becomes stronger, and the distance (stroke) between the valve body tip and the nozzle inlet becomes shorter.
Conversely, if the paint pressure decreases, the stroke becomes longer. The shorter the stroke is, the larger the fluid resistance is, and the longer the stroke is, the smaller the fluid resistance is. Therefore, a substantially constant flow velocity can be obtained by the stroke of the movable iron core, that is, the valve body according to the pressure fluctuation. As a result, it is possible to perform marking with a stable dot diameter even in an environment in which the paint pressure fluctuates easily.

At the same time, when the energizing time to the solenoid is limited to 0.02 to 2.00 ms so that the force of the solenoid pulling up the movable iron core does not change due to the change in paint pressure, the movable iron core is fixed. By setting the current value so that it moves within the range not touching, the movable core and the fixed core do not collide with each other, and it is possible to take a stroke according to the pressure fluctuation.

[0026]

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a marking device according to the present invention.

FIG. 2 is a principle diagram illustrating an operation of the marking device according to the present invention.

FIG. 3 is a diagram showing an experimental result of measuring a relationship between a paint pressure and a discharge amount of the marking device according to the present invention.

FIG. 4 is a vertical cross-sectional view of a conventional marking device.

FIG. 5 is a diagram showing a connection of paint supply means.

[0027]

[Explanation of symbols]

10 Drive 11 fixed iron core 12 movable iron core 13 solenoid coil 20 Marking head 23 valve housing 24 valve 25 Guide 26 Pressure paint filling section 27 Paint supply hole 28 Connecting rod 29 springs 30 seat 31 nozzle inlet 32 injection nozzle 41 aerosol paint can 42 Piping loop 43 Marking controller 44 Marking device body D Gap between guide part and valve body

Continued front page    F-term (reference) 2C057 AF22 AG10 AG17 AG37 AG51                       AH20 AQ06 BF04                 4D073 AA02 BB03 CA15 DB02                 4F041 AB02 BA10 BA31 BA36

Claims (7)

[Claims] 1. A fixed iron core, a movable iron core that is adjacent to the fixed iron core with a gap therebetween in the longitudinal axis direction, a drive section including a solenoid coil around these iron cores, and a marking head section that is adjacent to the drive section in the vertical axis direction. The marking head portion includes a valve body connected to the movable iron core via a connecting rod, a valve housing having a valve seat on which the valve body is seated, and a nozzle inlet at the center of the valve seat. In a marking device for ejecting paint, ink, etc., which comprises a nozzle extending along a vertical axis and a pressure liquid filled portion formed in a space between the valve body and a movable iron core, the valve body has a cylindrical shape. And a guide member having a cylindrical hole in which the valve body is slidably fitted in the valve housing with a gap formed in the valve housing, and the movable iron core has a solenoid between the guide portion and the valve body. When the valve body connected to the movable iron core is opened by the suction by the valve body, the valve body is closed by the force of the liquid flowing from the pressure liquid filled portion to the nozzle inlet side at a high speed through the gap of the guide portion. A marking device having a minute gap that is carried in the direction of closing the seat. 2. The marking device according to claim 1, wherein the pressure loss of the valve body and the guide portion is 0.3 to 3 times the pressure loss of the nozzle portion. 3. The nozzle diameter of the guide gap is 0.1 mm.
When it is, it is 20 to 50 μm.
Marking device according to. 4. The energization time to the solenoid is 0.02 to 2.0.
The marking device according to claim 1, wherein a current value is set such that the movable iron core moves within a range where the movable iron core does not touch the fixed iron core when the time is 0 ms. 5. The marking device according to claim 1, further comprising a movable iron core return spring having a weak force enough to support the movable iron core along the connecting rod. 6. The marking device according to claim 1, further comprising a pressurized aerosol paint can as a means for supplying paint or the like. 7. The marking device according to claim 6, wherein a paint pipe connecting the aerosol paint can and a supply port for paint or the like is looped so that the paint can be prevented from settling.