JPH0822422B2 - How to manage the squirt pattern of a liquid - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for managing ejection or ejection patterns from a liquid gun.

Recently, the demand for welded cans has rapidly increased in the can industry. For the weld seam part of the can body that constitutes these welded cans, in order to prevent corrosion and elution of the metal into the contents,
A strip coating with plastic is applied from the inside (see Fig. 1). Examples of the strip coating method include brush coating and coating by roll or spray.

The most important thing to note in the above-mentioned strip application is that the width of the strip is constant. The reason is as follows. Originally, paint (5P) was applied to the entire surface of the inside of the can body before welding as shown in FIG. However, there is no paint around the joints because of welding. That is, the metal part (5M) of the can is exposed.
After welding, the exposed portion is coated with the strip coating as described above.

The most widely adopted method as the above-mentioned strip coating method is a hot airless spray system developed by Nordson Corporation (US). The reason is that compared with the above-mentioned contact method, this method can keep the liquid pressure, temperature, viscosity, etc. of the paint constant, and the most stable one, that is, width and thickness, as long as the nozzle diameter does not change. This is because a constant strip-shaped coating is applied. The rights to the above process are assigned to the applicant.

However, there was one crying point in the hot airless spray system. It is compelled to use nozzles with relatively small orifices. The diameter is as small as 0.1 to 0.3 mm when converted to a circle, and in practice, the phenomenon of nozzle clogging may occur. Needless to say, the nozzle clogging immediately reduces the ejection amount, affects the spray pattern, and reduces and reduces the width and thickness of the strip. That is, a defective product is generated. If these discoveries are delayed on the can manufacturing line that flows at a high speed of around 50 m / min, hundreds of defective products will occasionally occur again. This not only causes a great loss, but also becomes a serious problem if uncoated cans are shipped. In order to prevent this, the industry pays great attention to prevent the occurrence of defective products. As one of the means, the photocells L ₁ and L _{2 are} currently used.
The splay pattern is checked by means of (see FIG. 2). However, with this method, it is possible to check when the nozzle is completely clogged, but it is difficult to check when it is around 50%. There is also a method of checking the width of the strip after coating, but this is also difficult to perform a strict check as in the case of the above-mentioned photoelectric tube.

The motive of the present invention was to strictly check the widths of the strips applied in strips, to immediately discover these and to take appropriate countermeasures to perform strict and effective production control.

An object of the present invention is to detect a slight change in discharge pressure in a liquid gun and a nozzle, detect a change in a spray pattern corresponding to the change, and take appropriate countermeasures to prevent the occurrence of defective products. To prevent.

The gist of the present invention is to electrically detect the fluctuation of the ejection pressure on the liquid passage upstream of the nozzle, and to output the signal and a reference numerical value set in advance separately in the computer every time in milliseconds. In contrast to the above, the method and apparatus for detecting and transmitting the pressure in the case of exceeding the above standard range and taking the necessary control measures.

First, the method of the present invention will be described. See FIG.
First, the basics of this method will be described. Nozzle inside gun 11
An electric pressure sensor 16 is provided on the liquid passage 14 close to 19 or further on the upstream passage. Nozzle hole 19
When foreign matter is clogged near H, the liquid pressure in the liquid passage instantaneously rises in proportion to the amount. The electric pressure sensor 16 detects it and sends an electric signal. The electric signal is sent to the amplifier (A via the explosion protection device (EPB) 21 if necessary).
MP) 22 to be amplified and further converted into a digital value through the analog-digital converter (A / D) 23 and input into the CPU 26. In parallel with that, a numerical value of the pressure within an allowable range which is a reference to the pressure is calculated from a set value by a program previously input in a read-only storage device (ROM) 24 in the CPU, and a readable / writable memory is stored. Device (RAM) 25
(See FIG. 4). The above CPUs compare and compare the numerical values of both, and if the values are the same within a certain setting range, it is as it is, and if the actual pressure deviates from the reference range, it outputs a signal and inputs / outputs. It is notified by an alarm device or the like via the device (I / O) 27. As a result, the pattern applied by the spray from the gun, that is, the width of the strip,
It turns out that they are out of the standard. As a further example, if the nozzle is clogged, the detected pressure rises, and when the nozzle exceeds the permissible range, it is transmitted. At the same time, the ejection amount is reduced and the width of the coating pattern is reduced. Further, when the nozzle hole diameter increases due to abrasion or the like, the detected pressure drops, and conversely, the ejection amount increases and the increase in the width of the coating pattern is transmitted and notified.

In addition, the set value transmitted from the storage device is transmitted every repeat time in milliseconds. This is to check the pattern in very small increments, and not to miss a few scars. For example, suppose it takes 50 milliseconds to apply a 100 mm long strip. 1
It means that it will be applied for 2 millisecond, but at this time, the length
It is assumed that a narrow width (sema) of 10 mm occurs. Checking every 30 milliseconds, this 10-millimeter defect misses and ends. However, it can be supplemented every 5 milliseconds. According to the present invention, this time is 0.1 to 10 milliseconds. During this time, even small defects can be found.

As described above, this method detects fluctuations in pressure at the time of ejection every millisecond and judges whether or not the coating patterns are appropriate.

Further, if necessary, the above transmission number is transmitted to the management device which requires it. For example, a recording device, a work marking device, a work removing device, or the like. It should be noted that the recording device or the like can always record even when the detected pressure is within the allowable range.

Further, the pressure calculated from the set value and stored in the RAM is an allowable range based on the hydraulic pressure upstream of the nozzle when ejecting a proper coating pattern having no problem, which has been confirmed in advance by a test or the like.

Further, the detected transmission obtained at each repeating time of the millisecond unit may sometimes cause a false alarm, for example, noise of another kind to be mixed. If it is transmitted multiple times in succession, it is confirmed that it is not noise. Therefore, in the present invention, it is also possible to set the number of times of consecutive overlaps and to make the transmission only when the same number of times is transmitted. You can do it.

Further, in selecting the allowable range of the pressure, the following settings can be made. First, the outline pressure is determined in advance. Next, set a range within this frame and set this to 2 ⁿ
-1 Divide into equal parts. Further, among these 2 ⁿ −1 equal parts, the upper limit value, the lower limit value, etc. are determined above and below the reference point.
For example, the maximum frame pressure is 10 kg / cm ² , and then the pressure is 2 Kg / cm ^2.
Determine a range of cm ² and 8 kg / cm ² , and divide this into 2 ⁸ −1 equal parts. 1
The scale is (8-2) ÷ 255 ≈ 0.0235 Kg / cm ² . In this case, the standard is 4.35Kg / cm ² , the upper limit is 5.5Kg / cm ² (4.35 + 0.0235
× 50 scale), the lower limit ^{3.7Kg / cm 2 (= 4.35-0.0235 ×} 25 scale) it is possible to choose the like.

In the above, the detection target is limited to the hydraulic pressure,
In addition, it is also possible to detect the current voltage of the electromagnetic valve for opening and closing the valve of the gun, the air pressure of the air cylinder, and the like, and manage them in association with the liquid pressure. For example, there is a case where a valve failure causes an inadequate opening / closing operation, which causes fluctuations in the hydraulic pressure. The above-mentioned valve failure can be generally detected by monitoring current and voltage in the case of an electromagnetic valve and air pressure in the case of an air cylinder. Thus, the method also detects these and compares them against the preset values of the pre-installed normal current voltage or air pressure program. Thereby, in the case of abnormality detection, it can be immediately judged that the gun valve system is out of order.

As described above, in order to judge the size of the applied pattern by detecting the pressure when ejected from the nozzle, it is desirable to detect the pressure in as small a step as possible, that is, as sensitively as possible. For that, it goes without saying that the sensor with the highest sensitivity is used, but in addition to that,
The sensitivity can be further increased by using a gun that has a large difference in fluid pressure variation even with the same ejection amount. For example, as shown in FIG. 3, a flow restrictor 17 is provided upstream of the liquid passage of the electric pressure sensor 16 to increase the pressure drop of the liquid after passing through the flow restrictor. To tighten. If the nozzle is clogged in this state and the nozzle is clogged, the pressure rises, but the amount is relatively large because it is lower than the original pressure as described above. That is, since the detection width is wide, the detection, that is, the sensitivity can be increased little by little. When the hole diameter of the nozzle becomes large due to abrasion or the like, the pressure drops, but the width of the drop also becomes relatively large, so the sensitivity increases.

Next, the device of the present invention will be described. Gun entrance 10
Is connected to the liquid supply device L by a pipe 9 as in the conventional case,
A pressure sensor 16 is provided on the liquid passage 14 inside the gun,
In the downstream liquid passage, there are a needle valve 15 and a nozzle 19
Etc. are attached. The pressure sensor 16 has an electric wiring 20.
Therefore, if necessary, via the explosion protector 21 to the amplifier 22
Further, it is electrically connected to an input unit of a central processing unit (CPU) 25 through an A / D converter, and a storage device (ROM 24 and RAM 25) is electrically connected to the input unit. An input / output device (I / O) 27 is connected to the output part of the CPU, and is electrically connected to the pressure range setting device 28 and the required management device 30 from the same device.

In order to increase the sensitivity of the electric pressure sensor, that is, to increase the width of pressure fluctuation, as shown in FIG.
17 may be provided on the liquid passage and upstream of the electric pressure sensor.

CPU in the above device, through the I / O, alarm device or stop device, recording device, marking device to the work,
It is connected to the work exclusion device by wiring.

Although the case of jetting has been described above, this can be applied to jetting without any problem. Furthermore, these jets and discharges
It can be applied to both continuous and intermittent systems. A pressure diagram in the case of the continuous type is shown in FIG. 4, and a case of the intermittent type is shown in FIG. However, in the case of the intermittent type device, it is necessary to connect the timer T to the coil 18 of the solenoid valve as shown by the phantom line in FIG.

As described above, according to the present invention, particularly in a work requiring a strict striped coating width, a clogging phenomenon in the nozzle that is likely to occur or an excessive ejection discharge due to abrasion of the nozzle hole diameter or the like is discovered in advance, Appropriate countermeasures are taken to prevent the generation of unnecessary products, and the defective products that have occurred are excluded from the production line to prevent the outflow of defective products to the market.

[Brief description of drawings]

FIG. 1 is a perspective view in which a strip coating of plastic is applied to the joint of the can body of a welding can. FIG. 2 is a conventional method for checking the strip coating width using a photoelectric tube. FIG. 3 is a diagram showing the method and apparatus according to the present invention. Description and Configuration Diagram FIG. 4 is a diagram of a pressure allowable range and time during jetting or discharging in the continuous jetting or discharging of the present invention. FIG. 5 is a pressure during jetting or discharging in the intermittent jetting or discharging of the present invention, Diagram of current value of solenoid valve for gun Explanation of main symbols 1,5 …… Can barrel, 2 …… Seam, 3…
… Plastic strip coating, 11 …… Gun, 14 …… Liquid passage, 15 …… Valve, 16 …… Electric pressure sensor, 17 ……
Flow restrictor, 19 ... Nozzle, W ... Strip coating width, D ...
Strip application thickness

Claims (2)

[Claims] 1. A method of jetting a liquid, comprising: (1) in a liquid pipe (9) or in a liquid passage (14) in a gun (11) having a valve (15) mounted on the pipe. , The detected electric pressure is transmitted by an electric signal by an electric pressure sensor (16) provided, (2) The electric signal of the pressure and a preset unit of 0.1 to 10 milliseconds apart from the electric signal. The reference value of the permissible range of the ejection pressure for each repetition time is compared and compared in the computer, and the pressure outside the permissible range is repeated every millisecond. A method for managing a liquid ejection pattern, which comprises: detecting and transmitting, thereby indirectly detecting the state of the pattern ejected from the gun. 2. A liquid jetting or discharging method comprising: (1) a liquid passage (14) in a gun (11) having a valve (15) mounted in the liquid pipe (9) or on the pipe. The electric pressure sensor (16) provided therein causes the detected pressure to be transmitted by an electric signal, and (2) the electric signal of the above pressure and a preset value of 0.1 to 10 mm apart from the electric signal. Repeatedly in units of seconds, the reference value of the allowable range of the jet pressure is compared and compared in the computer every time, and the pressure outside the allowable range is repeated in the unit of milliseconds. And (3) sending a pressure detection signal outside the permissible range to a required management device to perform those management operations. How to manage.