High Voltage Detection Device for Powder Spray

Abstract

[Problem] To provide a high voltage detection device for powder spray that can detect high voltage of multiple adjacent discharge lines in a narrow space that serves as a closed space for powder dispersion. [Solution Means] The high voltage detection device (10) of the powder spray according to the present invention comprises a dispersion unit (20) having a powder storage tank, a dispersion roller, and a discharge line, and a scattering prevention unit (30) having two scattering prevention rollers and a discharge line that are arranged on the downstream and upstream sides immediately below the dispersion unit to form a dispersion closed space between the rollers and are arranged with a gap from the object to be dispersed and are forcibly rotated, and a detection means (40) that detects a high voltage applied to a discharge line by being close to the discharge line of the powder spray, wherein the three discharge lines are close to each other at the vertex position of a triangle when viewed in a cross-section perpendicular to the longitudinal direction, and A signal processing means (50) is provided to process the detected high voltage connected to the detection means and determine the live state of the discharge line, and The detection means is characterized by surrounding the area other than the detection surface of a detection electrode with a length equal to the diameter of the discharge line, facing the discharge line, with an electric field shielding part, and the signal processing means is characterized by being set to a gain that enables detection at a close distance from the discharge line in the amplification part.

Description

Technology Field

[0001] The present invention relates to a high voltage detection device for a powder spray that detects a high voltage applied to a powder spray (also called a powder spraying device) that sprays powder onto the surface of a plastic film or rubber sheet, etc., in order to prevent mutual adhesion (blocking) of wound laminates, plastic films or rubber sheets, etc., and to improve slipperiness in subsequent processes. Background Technology

[0002] There is a powder spray that disperses powder to prevent blocking and improve slipperiness (see Patent Document 1). FIG. 9 is an explanatory diagram of a discharge line of a conventional powder spray.

[0003] The powder spray (1) has a scattering unit (20) positioned at the center top, and scattering prevention units (30) are positioned at the oblique lower side of the scattering unit (20), in other words, on the left and right sides (upstream and downstream sides with respect to the conveying direction of the printing device) when viewed from the roller cross-section. The scattering roller (24) rotates along the conveying direction of the printing device, the upstream scattering prevention roller (32) rotates in the opposite direction to the conveying direction, and the downstream scattering prevention roller (32) rotates along the conveying direction, and the space surrounded by the three rollers becomes a scattering closed space (13). Within the scattering closed space (13), powder attached to the roller surface of the scattering roller (24) is scattered by discharge. Additionally, the scattering prevention roller (32) also separates powder attached to the roller surface by discharge. The scattering roller (24) and the scattering prevention roller (32) have discharge lines (26, 34) positioned close to generate discharge on the roller surface. The discharge line (26) of the scattering roller (24) is positioned at the bottom of the roller within the scattering closed space (13). The bottom of the scattering roller (24) is located at the top of the scattering closed space (13), from which the powder attached to the roller can be released and scattered within the space without bias. The discharge line (34) of the scattering prevention roller (32) is positioned slightly below the horizontal line passing through the axis within the scattering closed space (13). At this position, the powder attached to the roller of the scattering roller (24) can be discharged without affecting the powder and without interfering with the scattering target below.

[0004] These discharge lines (26, 34) are positioned close to the rollers at a distance of several millimeters, specifically 1 mm, without contacting the rollers. The discharge lines (26, 34) are flexible wires with a conductor coated with an insulator, and are connected to a high-voltage transformer and commercial power supply via a plug-type cable, with a voltage of 7 kV applied, which is stepped up by the high-voltage transformer. The powder that has been moved downward by the scattering roller (24) is released by the discharge from the discharge line (26). At that time, the powder attached to the scattering prevention roller (32) is released by the discharge from the discharge line (34), and the powder can be scattered onto the surface of a scattering target object, such as a plastic film or a rubber sheet, moving downward by the scattering prevention roller (32).

[0005] During maintenance of the powder spray, in order to ensure safety of the operation, the plug of the cable connected to the high-voltage transformer was removed from the main body socket of the spray unit and the scatter prevention unit.

[0006] Furthermore, at the end of maintenance, the plug was installed in the socket. Conventionally, there were occasional instances where the plug installation was forgotten upon completion of maintenance. If the powder spray is operated without applying high voltage to the discharge line, the powder carried downward by the rotation of the scattering roller and the anti-scattering roller forms clumps and adheres to the surface of the object to be sprayed. Since the object to be sprayed was conveyed at high speed from below the spray, the powder clumps adhered over a long distance, resulting in significant product loss. Additionally, maintenance work on the powder spray was required, necessitating a prolonged suspension of the powder spray operation. Other causes for the failure to generate high voltage include the deterioration of the high-voltage transformer and the discharge line. For this reason, a detection device capable of detecting the high voltage applied to the discharge line was anticipated.

[0007] Conventionally, there is a technology disclosed in Patent Documents 2 and 3 as a technology for detecting high voltage applied to a conductor.

[0008] The technology disclosed in Patent Documents 2 and 3 has a detection distance of about 1 m (Patent Document 2) and a predetermined distance (generally several m as a distance to prevent electric shock accidents), and the directivity of the detection range is 180 degrees (Patent Document 2) and omnidirectional (Patent Document 3).

[0009] In addition, the technology disclosed in Patent Documents 2 and 3 is assumed to be grounded by forming a capacitor through the floating capacitance generated between the detection target, the detection means, the human body, and the ground, respectively, by mounting the device on the human body. Therefore, the device configuration does not include an earth terminal.

[0010] The dispersion spray subject to high-voltage detection in the present invention is a special location in which three discharge lines are arranged at a close distance (tens of mm) from each other at the vertices of a triangle when viewed from a cross-section perpendicular to the longitudinal direction, in a narrow space that serves as a closed space for the dispersion of powder. For this reason, device configurations such as those in Patent Documents 2 and 3 cannot detect multiple discharge lines individually, making them inapplicable.

[0011] In addition, since a person cannot be stationed in close proximity to the discharge line to which high voltage is applied, if there is no ground terminal, the circuit for detecting high voltage cannot be protected from high voltage. Prior art literature

[0012] Japanese Patent Publication No. 3773191, Japanese Patent Publication No. 58-17372, Japanese Published Patent Application No. 2010-203961 The problem to be solved

[0013] The problem that the present invention aims to solve is to provide a high voltage detection device for powder spray that can detect high voltage of multiple adjacent discharge lines in a narrow space that becomes a closed space for powder dispersion, in light of the problems of the prior art above. means of solving the problem

[0014] The present invention, as a first means for solving the above problem, comprises a dispersion unit having a powder storage tank, a dispersion roller, and a discharge line, and a dispersion prevention unit having two dispersion prevention rollers and a discharge line disposed on the downstream and upstream sides immediately below the dispersion unit to form a dispersion closure space between the rollers and arranged with a gap from the object to be dispersed and forcibly rotated, and three of the discharge lines are close to each other at the vertex positions of a triangle when viewed in a cross-section perpendicular to the longitudinal direction, and a detection means for detecting a high voltage applied to the discharge line while close to the discharge line of the powder spray.

[0015] A signal processing means is provided to process the detected high voltage connected to the above detection means and to determine the live state of the discharge line.

[0016] The present invention provides a high-voltage detection device for powder spray, characterized in that the detection means surrounds the detection surface of a detection electrode, which is positioned opposite the discharge line and has a length approximately equal to the diameter of the discharge line, with an electric field shielding portion, and the signal processing means is set to a gain that allows detection at a close distance from the discharge line in an amplification portion.

[0017] According to the first means above, the live state of multiple discharge lines located close together in a confined space can be detected individually. In addition, even if an error in the installation position occurs with each replacement of the discharge lines, the detection electrode can detect the high voltage of the opposing discharge line without contacting the discharge line.

[0018] The present invention provides a high-voltage detection device for powder spray, wherein, as a second means for solving the above problem, the signal processing means of the first means is characterized by having a lightning arrester on the side of the detection means.

[0019] According to the second means above, if insulation breakdown occurs due to discharge (which is caused by deterioration over time due to current flow to the discharge line, insulation degradation due to powder adhering to the surface of the discharge line, interference with scattered material, or damage during replacement of the discharge line) and leakage occurs to the detection electrode, there may be cases where the power voltage is not stabilized due to malfunction or noise, but since the power is configured to be discharged directly to the ground from the ground terminal of the lightning protection unit, the signal processing means can be protected.

[0020] The present invention provides a high-voltage detection device for powder spray as a third means for solving the above problem, wherein, in the first means, the detection electrode is characterized by using stainless steel containing molybdenum in its material.

[0021] According to the third means above, corrosion of the detection electrode surface can be reduced by ozone generated by partial discharge.

[0022] The present invention provides a high-voltage detection device for powder spray, wherein, as a fourth means for solving the above problem, the signal processing means in any one of the first to third means is configured to interchangeably configure a low-pass filter and a band-pass filter.

[0023] According to the above fourth means, either high voltage or corona discharge can be detected by switching between them as required. Effects of the invention

[0024] According to the present invention, the live state of multiple discharge lines located close together in a narrow space that becomes a closed space for the dispersion of powder can be individually detected. Brief explanation of the drawing

[0025] Figure 1 is a schematic diagram of a high-voltage detection device for a powder spray according to the present invention. Figure 2 is a plan view of the operating position (closed state) of the powder spray. Figure 3 is a plan view (1) of the maintenance position (open state) of the powder spray and a BB cross-sectional view (2) of (1). Figure 4 is an enlarged cross-sectional view of the AA arrow in Figure 2. FIG. 5 is a side view (1) of the detection means of the dispersion unit and a CC cross-sectional view (2) of (1). FIG. 6 is a plan view (1) and a side view (2) of the detection means of the scatter prevention unit. Figure 7 is an explanatory diagram of the detection means. Figure 8 is a schematic diagram of a high-voltage detection device for a powder spray, which is a modified example. Figure 9 is an explanatory diagram of the discharge line of a conventional powder spray. Specific details for implementing the invention

[0026] An embodiment of the high-voltage detection device for a powder spray according to the present invention will be described in detail below with reference to the drawings.

[0027] [Powder Spray (1)]

[0028] First, the powder spray to be installed according to the present invention will be described below. FIG. 2 is a plan view of the operating position (closed state) of the powder spray. FIG. 3 is a plan view (1) of the maintenance position (open state) of the powder spray and a BB cross-sectional view (2) of (1). FIG. 4 is an enlarged cross-sectional view of the AA arrow in FIG. 2. FIG. 5 is a side view (1) of the detection means of the dispersion unit and a CC cross-sectional view (2) of (1). FIG. 6 is a plan view (1) and a side view (2) of the detection means of the scattering prevention unit.

[0029] As described above, the powder spray (1) comprises a spreading unit (20) having a powder storage tank (22), a spreading roller (24), and a discharge line (26), two scattering prevention rollers (32) positioned on the downstream and upstream sides immediately below the spreading unit (20) to form a spreading closed space (13) between the rollers and arranged with a gap from the object to be scattered and rotated by force, and a device stand (12), and scatters powder onto the object to be scattered passing under the scattering prevention rollers (32). Additionally, one discharge line (34) is installed on each of the two scattering prevention rollers (32), so that the scattering unit (20) and the scattering prevention unit (30), which consists of the scattering prevention rollers (32) and the discharge line (34), can be moved to an operating position close to each other and a maintenance position far apart from each other, thereby providing a space for replacing the discharge lines (26, 34) at the maintenance position.

[0030] The scatter prevention unit (30) moves horizontally from the device frame (12). The specific configuration is such that two scatter prevention rollers (32) and a discharge line (34) positioned below the scatter unit (20) are divided along a vertical line passing through the axis of the scatter roller (24), in other words, from the center of the device frame (12), to form a unit (referred to as the scatter prevention unit (30)) in which one scatter prevention roller (32) and one discharge line (34) are each positioned on a unit frame (36). The discharge line (34) installed on the scatter prevention roller (32) of the unit is positioned by using a pulley (17) to bend the wire in a direction intersecting the longitudinal direction (obtuse angle in FIG. 3) from both ends of the scatter prevention roller (32) outwardly, with a fixing screw on one end of the scatter prevention roller (32) and a lock and a coil spring on the other end. Two such scatter prevention units (30) are arranged symmetrically on the left and right sides with the scatter unit (20) as the center. Additionally, the discharge line (34) may be installed in a straight line without using a pulley.

[0031] The device stand (12) is provided with a mounting platform (14) on which the unit stand (36) can move horizontally on the stand.

[0032] [High voltage detection device for powder spray (10)]

[0033] Figure 1 is a schematic diagram of a high-voltage detection device for a powder spray according to the present invention. The high voltage detection device (10) of the powder spray according to the present invention comprises a dispersion unit (20) having a powder storage tank (22), a dispersion roller (24), and a discharge line (26); a scattering prevention unit (30) having two scattering prevention rollers (32) and a discharge line (34) that are arranged on the downstream and upstream sides immediately below the dispersion unit (20) to form a dispersion closed space (13) between the rollers and are arranged with a gap from the object to be dispersed and are forcibly rotated; a detection means (40) that detects a high voltage applied to the discharge line (26, 34) by being close to each other at the vertex position of a triangle when viewed in a cross-section perpendicular to the longitudinal direction, and is close to the discharge line (26, 34) of the powder spray (1); and a signal processing device connected to the detection means (40) that processes the detected high voltage to determine the live state of the discharge line (26, 34). The means (50) is provided, and the detection means (40) is positioned opposite the discharge line (26, 34), and the detection surface of the detection electrode (42), which has a length approximately equal to the diameter of the discharge line (26, 34), is surrounded by an electric field shielding part (44), and the signal processing means (50) is set to a gain that can detect at a close distance from the amplification part (53) and the discharge line (26, 34).

[0034] One end of the discharge line (26, 34) is connected to the high-voltage transformer (2) and the commercial power supply (3), and the other end is grounded.

[0035] (Detection means (40))

[0036] FIG. 7 is an explanatory diagram of the detection means. The detection means (40) has a detection electrode (42) and an electric field shield (44). The detection electrode (42) is a rectangular electrode with a length equal to or nearly equal to the diameter of the discharge lines (26, 34), and is positioned at a predetermined distance without contacting the discharge lines (26, 34). To reduce the corrosive action on the electrode surface caused by partial discharge, the detection electrode (42) is made of a metal material such as stainless steel containing molybdenum, for example, SUS316, SUS316L, etc. Additionally, the electrode surface is polished smooth so that it does not deteriorate when in contact with the discharge lines (26, 34).

[0037] The electric field shielding part (44) is an insulating resin member made of a low dielectric constant material that covers the detection surface of the detection electrode (42), in other words, the surface facing the discharge line. The electric field shielding part (44) is formed in a concave shape into which the rectangular detection electrode (42) is inserted, and the directionality of the detection surface is limited to a predetermined range so that only the high voltage of one discharge line facing the electrode surface to be detected can be detected. In this embodiment, as an example, the distance between the discharge line (26, 34) and the detection electrode (42) is set to several millimeters, specifically within 3 millimeters. Thus, when the discharge line is replaced, detection is possible even when the center of the new discharge line (26, 34) and the center of the detection electrode (42) are misaligned within a range that does not affect the powder dispersion. For example, even if the tolerance of the parts constituting the powder dispersion device is within the allowable limit, there may be cases where the center positions differ when assembled.

[0038] In addition, since the back surface of the electric field shielding part (44) is grounded (earthed), it is electrostatically shielded and has no influence from external electric fields. By doing so, error detection is suppressed by not making the back surface of the electric field shielding part (44) directional.

[0039] (signal processing means (50))

[0040] The signal processing means (50) is connected to the detection means (40) via a cable (5) and has a lightning protection unit (51), a low-pass filter (52), an amplifier (53), a signal judgment unit (54), and an output unit (55) from the side of the detection means (40).

[0041] The lightning protection unit (51) is an earth terminal positioned closest to the detection means (40) among the components of the signal processing means (50), and is configured so that when an abnormal voltage, surge, or leak detected by the detection means (40) occurs, power is discharged directly from the earth terminal to the ground. By doing so, the circuit further downstream from the lightning protection unit (51) can be protected.

[0042] The low-pass filter (52) removes high-frequency noise that cannot be processed by the analog IC at the downstream end. This prevents the destruction of the analog IC by high-frequency noise.

[0043] The amplification unit (53) amplifies the noise-removed detection signal to a level that can be identified by the signal determination unit (54) at the rear end. In this embodiment, the amplification rate is adjusted by the resistance value of the semi-fixed resistor. It is set to a level that can be stably detected at a close distance from the discharge line (26, 34).

[0044] The signal determination unit (54) determines whether high voltage is generated by applying a preset threshold and whether the detection signal level amplified by the amplification unit (53) exceeds the threshold.

[0045] The output unit (55) converts the detection signal determined by the signal determination unit (54) into a voltage-free contact. At this time, the detection signal and the output signal are electrically isolated. As a result, there are fewer restrictions on the devices and circuits connected to the output unit (55). As an example of this embodiment, by connecting a Programmable Logic Controller (PLC) to the output unit (55), an output signal is transmitted to the input terminal of the PLC when a high voltage is detected.

[0046] (High voltage detection method for powder spray)

[0047] Next, a method for detecting high voltage of a discharge line of a powder spray is described below. After the high voltage detection device (10) of the powder spray is installed in a scattering unit or a scattering prevention unit, it receives power from the unit and becomes capable of measuring high voltage.

[0048] (1) Normal dispersion

[0049] In normal dispersion, the power supply to each unit is properly connected and power is supplied to each unit, and the power cables and signal lines connecting each unit are not disconnected. In addition, the high-voltage plugs of the discharge lines (26, 34) are properly connected to the sockets of the main body, and the powder is dispersed. At this time, the high-voltage detection device (10) of the present invention detects the high voltage from the discharge lines (26, 34) by the detection means (40), and the signal judgment unit (54) outputs an output signal above the threshold value of the high voltage to the outside.

[0050] (2) Abnormal dispersion

[0051] In the case of abnormal dispersion, the power supply to each unit is properly connected and power is supplied to each unit, but the dispersion occurs when a part of the power cable or signal line connecting each unit is disconnected or detached. Specifically, this includes cases where the high-voltage plug supplying high voltage to the discharge line is not properly connected to the socket of the main body and is detached, or where the high-voltage transformer is degraded, or where the discharge line is degraded. At this time, the high-voltage detection device (10) of the present invention does not detect high voltage from the discharge line (26, 34) by the detection means (40), and the signal judgment unit (54) outputs an output signal that does not meet the threshold value of the high voltage to the outside.

[0052] (Variation Example)

[0053] FIG. 8 is a schematic diagram of a high-voltage detection device for a modified powder spray. As shown, the high-voltage detection device (10A) for a modified powder spray has a different configuration of the signal processing means (50A), but the other configurations are the same as those in FIG. 1, so a detailed description is omitted. The signal processing means (50A) adopts the configuration of a filter section (52A). The filter section (52A) is equipped with a low-pass filter (522) as in the configuration of FIG. 1, and furthermore, a band-pass filter (523) is added. The band-pass filter (523) can detect partial discharge (corona discharge) by narrowing the frequency passing through the filter. Specifically, corona noise generated by corona discharge is treated as a signal source, and a filter is installed to prevent specific frequency bands included in the corona noise from passing through. Generally, the frequency range of corona noise spans a wide range from 15 kHz to 380 MHz, but the strength of the noise electric field has the characteristic of decreasing in almost inverse proportion to the frequency. For this reason, the signal level of corona noise was narrowed to a range that does not decrease excessively and does not exceed the upper operating frequency limit of the amplifier.

[0054] The filter section (52A) is equipped with a switching switch that switches between a low-pass filter and a band-pass filter.

[0055] According to the high-voltage detection device (10A) of the powder spray, which is a modified example of this, a low-pass filter or a band-pass filter can be selected via a switching switch as required, allowing for the measurement of high voltage or corona discharge. When detecting corona discharge, a threshold value is provided, similar to the high-voltage detection method. Accordingly, the high-voltage detection device (10A) detects corona discharge from the discharge line (26, 34) by the detection means (40), and the signal determination unit (54) outputs an output signal that is greater than or equal to the threshold value of the corona discharge. An advantage of detecting high voltage is that it is possible to determine the operating state of the high-voltage transformer being ON or OFF, determine whether the cable connecting the high-voltage transformer and the discharge line is connected, or determine whether high voltage is applied to the discharge line. Specifically, when the high-voltage transformer is ON and the cable connecting the high-voltage transformer and the discharge line is connected, a high voltage signal is detected because high voltage is applied to the discharge line.

[0056] As an advantage of detecting corona discharge, it is possible to determine whether high voltage is applied to the discharge line, and also to determine whether electrons ejected by the corona discharge collide with powder attached to the surface of the spreading roller, causing the powder to peel off from the surface of the spreading roller. Specifically, even if a cable connecting the high-voltage transformer and the discharge line is connected, when the output voltage drops due to the aging degradation of the high-voltage transformer, corona discharge does not occur even if high voltage is applied to the discharge line, which may lead to normal spreading not taking place and the powder flowing out. Therefore, by detecting corona discharge, a normal spreading state can be maintained.

[0057] According to the high voltage detection device for powder spray of the present invention, the live state of multiple discharge lines located close together in a narrow space that becomes a closed space for powder dispersion can be individually detected.

[0058] In this embodiment, the scatter prevention unit (30) is described as being configured to slide horizontally from the mounting stand (14) by a manual method; however, as long as it is capable of moving horizontally, it is not limited to this configuration, and an automatic method using an electric or fluid (air, hydraulic, etc.) drive cylinder can be adopted. In this case, if the scatter roller and the scatter prevention roller are aligned during the initial setup, even if the scatter prevention unit is moved horizontally during maintenance or discharge line replacement work, when it is returned to the operating position, it maintains the position from the initial setup, so there is no need to align the position again, and the discharge line replacement work can be performed in a short time.

[0059] The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiments in any way, and various modifications are possible within the scope of the present invention.

[0060] In addition, the present invention is not limited to the combinations disclosed in the embodiments and can be implemented by various combinations. Explanation of the symbols

[0061] 1 Powder Spray 2 High-voltage transformer 3 Commercial Power Supply 10, 10A High-voltage detection device for powder spray 12 device stands 13 Dispersion Closed Space 14 mounting bracket 16 fixing holes 17 pulleys 20 dispersion units 22 Powder storage tank 24 scatter rollers 26 discharge line 30 scattering prevention units 32 Anti-scattering rollers 34 discharge line 36-unit stand 40 detection means 42 detection electrodes 44 Electric field shielding section 50, 50A signal processing means 51 Lightning arrester 52 Low Pass Filter 52A filter section 53 Amplification section 54 Signal Judgment Unit 55 Output section 521 switch 522 Low Pass Filter 523 band pass filter

Claims

Claim 1 A high voltage detection device for a powder spray, comprising: a dispersion unit having a powder storage tank, a dispersion roller, and a discharge line; a dispersion prevention unit having two dispersion prevention rollers and a discharge line arranged on the downstream and upstream sides immediately below the dispersion unit to form a dispersion closed space between the rollers and arranged with a gap from the object to be dispersed and forcibly rotated; a detection means for detecting a high voltage applied to a discharge line in close proximity to the discharge line of the powder spray, wherein three discharge lines are close to each other at the vertex positions of a triangle when viewed in a cross-section perpendicular to the longitudinal direction, and a signal processing means connected to the detection means to process the detected high voltage and determine the live state of the discharge line; wherein the detection means is surrounded by an electric field shielding part except for the detection surface of a detection electrode having a length equal to the diameter of the discharge line, facing the discharge line, and the signal processing means is set to a gain that can be detected at a close distance from the discharge line in an amplification part. Claim 2 A high-voltage detection device for powder spray according to claim 1, characterized in that the signal processing means has a lightning protection unit provided on the side of the detection means. Claim 3 A high-voltage detection device for powder spray according to claim 1, characterized in that the detection electrode uses stainless steel containing molybdenum in its material. Claim 4 A high-voltage detection device for powder spray, characterized in that, in any one of claims 1 to 3, the signal processing means is configured to interchangeably configure a low-pass filter and a band-pass filter.

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