JP3339913B2 - Nozzle device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nozzle device for preventing a discharge from leaking due to wear of a nozzle discharge portion.

[0002]

2. Description of the Related Art When a paint is discharged from a nozzle and characters or symbols are written on a steel plate or the like and a glue is discharged and glued, a needle valve combining a nozzle and a needle is driven by a solenoid coil and a spring. In addition, a device for controlling the discharge of paint and paste is used.

FIG. 5 shows a sectional view of a marking nozzle for marking characters and symbols on a steel plate or the like with a paint as such an apparatus. The tip of the needle is fitted to the nozzle tip 1, and the needle 2 penetrates the diaphragm 3 and is joined to the plunger 8. The pressure chamber 6 is provided with a paint inlet 4. A fixed iron core 9 for sucking the plunger 8 is provided on the side opposite to the needle of the plunger 8, and a gap t between the plunger 8 and the fixed iron core 9 can be adjusted by a fixed iron core adjusting screw 12 and a nut 13 to set a stroke of the plunger 8. It has become. A solenoid coil 10 is provided so as to surround the plunger 8 and the fixed iron core 9, and when energized, the plunger 8 is sucked and moved in a direction in which the gap t becomes zero. The spring 11 is attached so as to press the tip of the needle 2 against the nozzle tip 1.

When performing marking or gluing, a signal voltage is applied to the solenoid coil 10, and the distance between the tip of the needle 2 and the nozzle tip 1 increases by t in accordance with the signal voltage.
The paint is discharged. In addition, a nozzle device using a piezoelectric element instead of the solenoid coil 10 has been used. FIG. 6 shows an example of a nozzle device using a piezoelectric element. Since the stroke of the piezoelectric element 21 is small, the stroke is enlarged using the lever 31 and the needle 33 is driven in the vertical direction. The tip of the needle 33 is pressed against the nozzle port 39 by the spring 35, and the tip of the needle 33 rises due to the extension of the piezoelectric element 21 to open the nozzle. A front end fitting 23 is provided at the front end of the piezoelectric element 21 and abuts one end of the lever 31, and the rear end is held down by an adjustment screw 50 and a lock screw 51.

[0005]

In the above-described method, the valve seat of the nozzle tip 1 and the tip of the needle 2 come into contact with impact each time one pulse is applied. Occurs. Especially with some paints
May contain materials that promote wear,
The use of such paints results in significant wear. When such wear occurs, the needle 2 is pressed by the spring 11 and moves toward the nozzle tip, so that the gap t increases. Therefore, it is necessary to adjust the gap t to a predetermined value by the adjusting screw 12 of the fixed iron core. However, it is very difficult to check the wear amount of the needle 2 and the nozzle tip 1 and adjust the gap t to the predetermined value. It was a tedious job.

In the case of a nozzle device using a piezoelectric element, such adjustment occurs as a problem of position adjustment of the piezoelectric element. Also in the case of the nozzle using the piezoelectric element shown in FIG. 6, the contact portion between the tip of the needle 33 and the nozzle port 39 is worn. To cope with this wear, a gap d is provided between the rear end of the piezoelectric element 21 and the adjusting screw 50 so that the tip of the needle 33 is pressed by the nozzle port 39 by the nozzle closing spring 35. By doing so, the lever ratio L1 / L is added to the wear amount.
Until the value obtained by multiplying 2 reaches d, the tip of the needle 33 and the nozzle port 39 are pressed by the spring 35 to be in close contact with each other when the nozzle is closed, and no leakage occurs. However, when the gap d is provided, the stroke of the piezoelectric element 21 decreases accordingly.
Each time the value obtained by multiplying the wear amount by the lever ratio L1 / L2 reaches d, the adjustment amount d must be set again by the adjustment screw 50 and the lock screw 51.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a nozzle device that automatically operates appropriately in response to wear of a needle and a nozzle tip fitted thereto. .

[0008]

In order to achieve the above object, according to the present invention, one end of a piezoelectric element is fixed to a fixing means, and the amount of expansion and contraction generated at the other end is added to one end of a lever supported at a fulcrum. In a nozzle device that transmits to a needle connected to the other end of the lever and opens and closes a gap between the needle tip and the nozzle port, the fixing means includes a casing that stores the piezoelectric element, and a casing that stores the piezoelectric element. The other piezoelectric element which is disposed in such a manner as to expand and contract in a direction perpendicular to the expansion and contraction direction of the piezoelectric element and is in close contact with the casing when expanded and compresses with a predetermined force, and fixes the other piezoelectric element and one end of the piezoelectric element The needle is connected to the one end of the lever substantially at right angles and rotatably at the rear end, and is biased by a spring so that the front end is pressed by the nozzle port. Those were.

In addition, a gap adjusting means for adjusting a gap between the other piezoelectric element in the expansion and contraction direction and the casing is provided.

Further, a time constant representing the response of a piezoelectric element drive signal of the piezoelectric element is made larger than the time constant of the other piezoelectric element.

[0011]

When a voltage is applied to the piezoelectric element and another piezoelectric element, the other piezoelectric element expands and contracts and applies a predetermined force to the casing. The generated frictional force suppresses the reaction force of the piezoelectric element, and the piezoelectric element is applied to the casing. However, when no voltage is applied, the other piezoelectric elements can move without contacting the casing.
The piezoelectric element coupled to this via the fixing portion is not restricted in the expansion and contraction direction. When no wear occurs between the needle tip and the nozzle port, the lever is assumed to be horizontal with the needle tip pressed against the nozzle port and the gap between them being zero. At rest when wear occurs,
Since the tip of the needle is pressed against the nozzle port by the spring, the lever is inclined toward the needle by the worn amount. When driving the piezoelectric element and another piezoelectric element in this state, the piezoelectric element expands and contracts based on the state in which the lever is tilted. In this way, the inclination of the lever changes according to the amount of wear, and the piezoelectric element expands and contracts based on the state of the tilted lever, so the relationship between the needle tip and the nozzle port is always the same regardless of the amount of wear. It will be automatically adjusted to be related.

The length of the other piezoelectric element in the direction of expansion and contraction and the gap between the casing and the casing are adjusted by the gap adjusting means, and the frictional force due to the compressive force generated when the piezoelectric element is extended can be set to a size that can withstand the reaction force of the piezoelectric element. .

When a voltage is simultaneously applied to the piezoelectric element and another piezoelectric element, the other piezoelectric element having a smaller time constant expands first to generate a compressive force, and then the other piezoelectric element expands and generates a compressive force. Be able to withstand power. Thus, the piezoelectric element is always fixed by another piezoelectric element when a voltage is applied.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of an embodiment of the present invention. A first piezoelectric element 21 that expands and contracts in the vertical direction and a second piezoelectric element 22 that expands and contracts in the horizontal direction are provided in the piezoelectric element casing 20. Each of the piezoelectric elements 21 and 22 is a laminated piezoelectric element having a cylindrical shape. Yes, it expands in the direction of the cylinder axis when DC voltage is applied, and returns to its original length when removed. One end of the first piezoelectric element 21 is provided with a tip fitting 23 for transmitting the amount of expansion and contraction, and the other end is a hollow cylindrical inner cylinder fixed to a fixing member 24 which is slidably fitted to the second piezoelectric element 22. I have. One end of the second piezoelectric element 22 is in contact with the piezoelectric element casing 20 so as to generate a sufficient frictional force when a force is applied, and the other end of the second piezoelectric element 22 has a gap smaller than the amount of expansion and contraction to the first adjustment screw 25. Are facing each other. The looseness of the first adjustment screw 25 is suppressed by the lock screw 26. The first spring 27 presses the first piezoelectric element 21 vertically downward via the fixing member 24, so that the tip fitting 23 does not separate from the lever 31. The set screw 28 holds down the first spring 27.

A pulse voltage is applied to each of the piezoelectric elements 21 and 22 from a connector 30 via a lead wire 29. A pulse voltage is applied to the connector 30 from a piezoelectric element drive circuit described later.

The lever 31 has a knife edge 32 as a fulcrum, one end of which supports the tip fitting 23, and the other end of which has a needle 33.
The spherical portion 34 at the upper end is rotatably supported. The tip fitting 23 and the lever 31 are connected by a knife edge.
The spherical portion 34 is pressed by the second spring 35. The second spring 35 is urged to press the tip of the needle 33 against the nozzle port 39, and is configured such that the pressing force can be adjusted by a second adjusting screw 36 screwed to the nozzle casing 37.

The tip of the needle 33 is pressed against the nozzle port 39 of the nozzle tip 38 by the pressing force of the second spring 35 to close the nozzle, and the tip of the needle 33 rises due to the extension of the first piezoelectric element 21 to open the nozzle. The diaphragm 40 forms a pressure chamber 41 together with the nozzle tip 38 in a state where the needle 33 can move up and down. A marking liquid such as paint or ink is supplied to the supply port 42 from a supply device (not shown) at a constant pressure, and is discharged from the nozzle port 39 by opening and closing the nozzle.

FIG. 2 shows a piezoelectric element driving circuit constituting the nozzle control circuit. A capacitor C is provided in parallel with the first piezoelectric element 21 and has a larger time constant than the second piezoelectric element 22.

The operation of the nozzle device configured as described above will be described. FIG. 3 shows a signal voltage applied to the piezoelectric elements 21 and 22 and a displacement amount of the piezoelectric elements 21 and 22. The timing and voltage of the signal voltage are determined by the shape or thickness of the character to be marked. When such a signal voltage is applied to the lead wire 29 from the connector 30, the piezoelectric elements 21 and 22 expand and contract a stroke according to the signal voltage.

When a voltage is applied to the first piezoelectric element 21 and the second piezoelectric element 22 at the same time, the second piezoelectric element 22 having a small time constant expands and presses the piezoelectric element casing 20 to generate a compressive force. Next, the first piezoelectric element 21 is extended, and the tip fitting 23 pushes down the left end of the lever 31 by the same amount as the amount of extension of the first piezoelectric element 21. At this time, the reaction force applied to the first piezoelectric element 21 is
It is opposed by a frictional force based on a compression force due to the extension of the piezoelectric element 22.

The lever 31 has a knife edge 32 as a fulcrum, expands and pulls up the spherical portion 34 according to a lever ratio (L2 / L1), and pulls up a needle 33 connected thereto. Open the gap to make the marking liquid dischargeable. When the pulse voltage is kept ON for a certain period of time and the voltage is set to 0 V, the first and second piezoelectric elements 21 and 22 are reduced to the original state, the spherical portion 34 is pushed down by the second spring 35, and the needle 33 is pushed down. At the same time, the diaphragm 40 is also pushed down, the volume of the pressure chamber 41 is rapidly reduced, and while the marking liquid is discharged from the gap between the tip of the needle 33 and the nozzle port 39, the tip of the needle 33 finally closes the nozzle port 39, The discharge of the marking liquid is stopped.

The operation of one pulse cycle shown in FIG. 3 has been described above. The relative movement between the nozzle device and the material to be marked is performed while continuously performing this operation, and the character locus is drawn as shown in FIG. Marking as shown in FIG. FIG. 4 shows a case in which the relative movement is performed so that the respective discharge amounts do not overlap. However, by moving slowly, continuous characters can be drawn.

When the ejection is performed for a long time, the tip of the needle 33 and the nozzle port 39 are worn due to frequent contact between the tip of the needle 33 and the nozzle port 39, and particles contained in the marking liquid. Will come. In the case of such wear, if the expansion / contraction stroke of the first piezoelectric element 21 is kept constant and its position does not change, the tip of the needle 33 completely closes the nozzle port 39 when the first piezoelectric element 21 extends and returns to its original position. And the marking liquid leaks.

However, the tip of the needle 33 and the nozzle port 3
9 is worn out, the first and second piezoelectric elements 21 and 22
When no voltage is applied to the first and second piezoelectric elements 21 and 22, no frictional force is generated by the second piezoelectric element 22.
And the fixing member 24 can move up and down.
Is pressed by the second spring 35 until the tip of the nozzle is pressed against the nozzle port 39. For this reason, the first and second piezoelectric elements 21 and 22 are connected by the lever 31 via the tip fitting 23.
When the first and second piezoelectric elements 21 and 22 start to expand and contract next time, the expansion and contraction operation is performed in a state where the first and second piezoelectric elements 21 and 22 start to expand and contract. Therefore, the tip of the needle 33 and the nozzle port 39 fitted with this
Even if is worn, the gap between the tip of the needle 33 and the nozzle port 39 caused by the wear is automatically corrected, so that the marking liquid does not leak.

[0025]

As is apparent from the above description, according to the present invention, the first piezoelectric element for opening and closing the nozzle port and the second piezoelectric element for fixing the nozzle only when energized are provided, and the position of the first piezoelectric element is set by the lever. The needle is moved by a spring provided on the needle side in accordance with the wear between the tip of the needle and the nozzle port, so that even if the wear occurs, the marking liquid is prevented from leaking from the gap between the needle tip and the nozzle port. be able to.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention.

FIG. 2 is a piezoelectric element drive circuit diagram.

FIG. 3 is a diagram illustrating a relationship between a pulse applied to a piezoelectric element and an amount of expansion and contraction of the piezoelectric element.

FIG. 4 is a diagram illustrating an example of marking according to the present embodiment.

FIG. 5 is a configuration diagram of a conventional marking nozzle.

FIG. 6 is a structural diagram of a marking nozzle using a piezoelectric element.

[Explanation of symbols]

 Reference Signs List 20 piezoelectric element casing 21 first piezoelectric element 22 second piezoelectric element 23 tip fitting 24 fixing member 25 first adjusting screw 26 lock screw 27 first spring 28 set screw 29 lead wire 30 connector 31 lever 32 knife edge 33 needle 34 spherical part 35 second spring 36 second adjusting screw 37 nozzle casing 38 nozzle tip 39 nozzle port 40 diaphragm 41 pressure chamber 42 supply port

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B05C 5/00-5/04 B05B 1/30-1/32

Claims (3)

(57) [Claims] 1. An end of a piezoelectric element is fixed to a fixing means, and the amount of expansion and contraction generated at the other end is added to one end of a lever supported at a fulcrum and transmitted to a needle connected to the other end of the lever. In a nozzle device that opens and closes a gap between a tip and a nozzle port to discharge a coating material, the fixing unit includes a casing that stores the piezoelectric element, and expands and contracts in the casing in a direction perpendicular to a direction in which the piezoelectric element expands and contracts. When the piezoelectric element is arranged and extended, the piezoelectric element is in close contact with the casing and compresses with a predetermined force, and the other piezoelectric element and a fixing portion for fixing one end of the piezoelectric element. A nozzle device characterized in that it is connected to the one end substantially at right angles and rotatably at the rear end, and is biased by a spring so that the front end is pressed by the nozzle port. 2. The nozzle device according to claim 1, further comprising a gap adjusting unit that adjusts a gap between the other piezoelectric element in the expansion and contraction direction and the casing. 3. The nozzle device according to claim 1, wherein a time constant representing a response of a piezoelectric element drive signal of the piezoelectric element is set larger than a time constant of the other piezoelectric element.