JP2023037785A - Method for checking electrical insulation of heat sealer - Google Patents

Abstract

To provide a method for checking electrical insulation of a heat sealer for checking an electrical insulation state of a conductive object to be sealed by the heat sealer.SOLUTION: There is provided a method for checking electrical insulation of a heat sealer, the heat sealer 1 comprising: a transformer 2 having a primary coil 21 and a secondary coil 22; a heater 4 electrically connected to the secondary coil 22; an insulating sheet 8 arranged between the heater 4 and a conductive sealing object 10; and a mounting table 9 having a conductive surface 91 on which the sealing object 10 is mounted. The conductive surface 91 is electrically connected to a reference potential portion G of the heat sealer 1. The method for checking electrical insulation of a heat sealer is configured to measure a resistance value between the heater 4 and the reference potential part G in a state where the heater 4 is in contact with the sealing object 10 placed on the conductive surface 91 through the insulating sheet 8 without supplying power to the primary coil 21, and to check an insulation property of the insulating sheet 8 based on a measured resistance value.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present disclosure relates to a method for confirming electrical insulation of a heat sealer that heat seals a conductive object to be sealed.

Patent Literature 1 listed below discloses an impulse heat sealer. In the impulse heat sealer, a relatively large electric current is applied to the heater only during heat sealing, and the temperature of the heater is instantaneously raised to a temperature at which heat sealing is possible. The impulse heat sealer disclosed in Patent Document 1 has a transformer inside. By energizing the primary coil of the transformer, the heater connected to the secondary coil is heated by electric power generated by electromagnetic induction.

Japanese Patent Application Laid-Open No. 2009-6604

There is a demand for heat-sealing a conductive object to be sealed with a heat sealer. For example, there are cases where a sheet member made of a thermoplastic resin containing a conductive filler is desired to be sealed. In such a case, it is necessary to insulate the current supplied to the heater so that it does not flow inside the object to be sealed. For example, the heater is pressed against the object to be sealed during heat sealing, and it is conceivable to perform heat sealing by interposing an insulating sheet between the heater and the object to be sealed. Here, if a hole is formed in the insulating sheet, the electric current supplied to the heater may flow inside the object to be sealed, and the object to be sealed may be scorched or a sealing failure may occur. Therefore, it is desired to check the electrical insulation state of the insulating sheet.

An object of the present disclosure is to provide a heat sealer electrical insulation confirmation method for confirming the electrical insulation state of a conductive sealing object in a heat sealer.

In the method for confirming electrical insulation of a heat sealer according to the present disclosure, the heat sealer includes a transformer having a primary coil and a secondary coil, a heater electrically connected to the secondary coil, and a sealing object having electrical conductivity with the heater. and a mounting base having a conductive surface on which the object to be sealed is mounted, wherein the conductive surface of the mounting base is a reference potential portion of the heat sealer. is electrically connected to the primary coil, and the heater is brought into contact with the sealing object placed on the conductive surface through the insulating sheet without supplying power to the primary coil. A resistance value between the heater and the reference potential portion is measured, and the insulating property of the insulating sheet is confirmed based on the measured resistance value.

The heat sealer further comprises: a ohmmeter connected between the secondary coil and the reference potential unit for measuring the resistance value; and a switch electrically connected in series to the ohmmeter. The switch may be closed when the resistance value is measured, and the switch may be opened when the heater is heated.

The insulating sheet may be attached to the heat sealer so as to cover the heater.

The switch is opened when the resistance value measured by the ohmmeter in the state in which the heater is brought into contact with the sealing object through the insulating sheet and the switch is closed is equal to or greater than a reference value. After that, the primary coil may be energized to heat the heater to heat-seal the object to be sealed.

It is a schematic block diagram of the heat sealer which performs the electrical insulation confirmation method which concerns on embodiment. FIG. 4 is an enlarged cross-sectional view showing the flow of electricity during heat sealing. 4 is a flow chart of the above method;

An embodiment of a method for checking electrical insulation of a heat sealer will be described below with reference to the drawings. The heat sealer 1 used in the present embodiment is an impulse heat sealer, and is intended to heat-seal a conductive object 10 to be sealed. The object to be sealed 10 of the present embodiment is, for example, a sheet member made of a thermoplastic resin containing conductive filler. For this purpose, the heat sealer 1 of the present embodiment has a special mechanism such as an insulating sheet 8 to be described later. can.

First, the configuration of the heat sealer 1 will be described. FIG. 1 is a simplified configuration diagram of the heat sealer 1, and the housing and the like are omitted. As shown in FIG. 1, the heat sealer 1 includes a transformer 2 that generates current in a heater 4 that heats an object 10 to be sealed when it is heat-sealed. The configuration including this transformer 2 is similar to that of a normal heat sealer. The transformer 2 has a primary coil 21 and a secondary coil 22 . Primary coil 21 is electrically connected to AC power supply 3 .

The heater 4 described above is specifically a nichrome wire and is electrically connected to the secondary coil 22 . When an electric current is applied to the primary coil 21 by the AC power supply 3, an electric current is applied to the secondary coil 22 by electromagnetic induction and the heater 4 generates heat. In the heat sealer 1, current is passed through the heater 4 only at the time of heat sealing, and the temperature of the heater 4 is instantaneously raised to a temperature at which heat sealing is possible. The heater 4 is normally raised, and is lowered during heat sealing to be pressed against the sealing object 10 via an insulating sheet 8, which will be described later. The elevation of the heater 4 may be performed automatically or manually, and the elevation mechanism has the same structure as that of a normal heat sealer.

The AC power supply 3 is connected to a controller 5 , which controls energization of the primary coil 21 , that is, heating of the heater 4 . When the heater 4 is moved up and down automatically by the heat sealer 1 instead of manually, the controller 5 also controls the up and down time of the heater 4 and the pressing time of the heater 4 against the object 10 to be sealed. In the case of manual operation, the controller 5 controls the AC power supply 3 so that current flows through the heater 4 while the heater 4 is pressed against the object 10 to be sealed. The controller 5 is composed of, for example, a CPU and a memory in which programs and data are stored.

The controller 5 is electrically connected to the reference potential section G of the heat sealer 1 . A reference potential portion G is a frame ground of the heat sealer 1 . Also, the heater 4 is electrically connected to a reference potential section G via a resistance meter 6 and a switch 7 . More specifically, the heater 4 is electrically connected to the reference potential section G via the ohmmeter 6 and the switch 7 at the electrical connection section with the secondary coil 22 . The switch 7 is electrically connected in series with the ohmmeter 6, and measurement by the ohmmeter 6 is possible when the switch 7 is closed. The resistance value measured by the ohmmeter 6 will be described later in detail. The switch 7 is opened when the heater 4 is energized by the transformer 2 . The ohmmeter 6 and switch 7 are also connected to the controller 5 and their operations are controlled by the controller 5 .

In the heat sealer 1 of this embodiment, an insulating sheet 8 is attached so as to cover the heater 4 from below. An electric current flows through the heater 4 itself when the heater 4 generates heat, and the insulating sheet 8 is provided so that this electric current does not flow from the heater 4 into the interior of the object to be sealed 10 having conductivity. The insulating sheet 8 of this embodiment is provided as a cover for the heater 4 and can be replaced. The insulating sheet 8 is made of a heat-resistant insulating material, such as a heat-resistant insulating resin sheet. Therefore, at the time of heat sealing, the insulating sheet 8 is sandwiched between the heater 4 and the object to be sealed 10 and transfers the heat from the heater 4 to the object to be sealed 10, but the current from the heater 4 to the object to be sealed 10 is reduced. Prevent leaks.

The heat sealer 1 also includes a mounting table 9 on which the object 10 to be sealed is mounted. The mounting table 9 may be an electric transfer device that automatically transfers the sealing target 10 or an automatic device such as an electric stacking device that automatically stacks the sealing target 10 . The mounting table 9 of this embodiment is an automatic device that operates on such electric power, and its reference potential portion G is electrically connected to the reference potential portion G of the heat sealer 1 described above. Specifically, the frame ground of the heat sealer 1 and the frame ground of the automatic device as the mounting table 9 are electrically connected. That is, the reference potential of the automatic device as the mounting table 9 of the heat sealer 1 is equal to the reference potential of the heat sealer 1 itself. Further, the upper surface of the mounting table 9 on which the object to be sealed 10 is mounted is formed as a conductive surface 91 having conductivity. The conductive surface 91 is electrically connected to the reference potential section G described above. That is, the potential of the conductive surface 91 is equal to the potential of the reference potential portion G.

Here, with reference to FIG. 2, the case where the insulating sheet 8 is damaged and the current flowing through the heater 4 during heat sealing leaks into the sealing object 10 will be described. FIG. 2 shows a state in which two holes 11 are formed in the insulating sheet 8 . In such a case, a closed circuit is formed during heat sealing as indicated by the dotted line in FIG. In this case, the internal resistance of the object to be sealed 10 generates heat, which may impair the appearance of the product. In addition, since part of the current that should flow through the heater 4 flows into the interior of the object 10 to be sealed, there is a risk that insufficient heat generation by the heater 4 may cause a sealing failure.

Therefore, in the heat sealer 1 of the present embodiment, it is confirmed whether or not dielectric breakdown has occurred in the insulating sheet 8 before heat sealing. The confirmation of electrical insulation may be performed for each heat sealing operation, for each predetermined number of heat sealing operations, or once a day. Even if the hole 11 is formed only at one place, the electrical conductivity from the heater 4 through the sealing object 10 depends on the potential difference between the heater 4 and the conductive surface 91 and whether or not a closed circuit is formed. Electricity can flow to surface 91 .

Next, the electrical insulation checking method described above will be described with reference to the flow chart shown in FIG. Here, the case where the heater 4 is raised and lowered and the heat generation is automatically performed by the controller 5 will be described. First, the object 10 to be sealed is mounted on the conductive surface 91 of the mounting table 9 for heat sealing. In FIGS. 1 and 2, sheet-like sealing objects 10 of the same material to be heat-sealed are placed on a conductive surface 91 in a superimposed state.

First, the heater 4 is lowered by the controller 5, and the heater 4 is pressed against the sealing object 10 via the insulating sheet 8 (step S1), and the switch 7 is closed by the controller 5 (step S2). Here, the switch 7 is closed (step S2) after the heater 4 is lowered (step S1), but these steps may be performed simultaneously, and the switch 7 may be closed before the heater 4 is lowered. Also, the switch 7 may be closed before the heater 4 is pressed against the sealing object 10 via the insulating sheet 8, or may be closed after it is pressed. At this time, power is not yet supplied from the AC power supply 3 to the primary coil 21 by the controller 5 , so no power is generated by the secondary coil 22 .

Here, as described above, the potential of the conductive surface 91 is equal to the reference potential of the reference potential section G described above, and one end of the ohmmeter 6 is electrically connected to this reference potential section G. On the other hand, when the switch 7 is closed, the other end of the ohmmeter 6 is connected to the heater 4, forming a closed circuit for resistance value measurement. The ohmmeter 6 measures the resistance value between the secondary side of the transformer 2, that is, between the heater 4 and the conductive surface 91. At this time, between the heater 4 and the conductive surface 91 are the insulating sheet 8 and the conductive surface 91. A sealing object 10 is interposed.

In addition, in this embodiment, the insulating sheet 8 is attached to the heat sealer 1 so as to cover the heater 4 . Therefore, the insulating sheet 8 can be interposed between the heater 4 and the object to be sealed 10 simply by lowering the heater 4, and the insulating sheet 8 is set between the heater 4 and the object to be sealed 10. The process is automatic.

Following steps S1 and S2, the resistance value is measured by the ohmmeter 6 (step S3). Here, if the insulating sheet 8 does not have the holes 11 and the electrical insulation is ensured, the measured resistance value will be sufficiently large. On the other hand, if the insulating sheet 8 has holes 11 and electrical insulation is not ensured, current flows from the heater 4 through the object 10 to be sealed. measured. The resistance value at this time is sufficiently smaller than the resistance value when the electrical insulation of the insulating sheet 8 is ensured. A reference value for judging electrical insulation is set between these two. Then, it is determined whether or not the measured resistance value is equal to or greater than the determination reference value (step S4).

If the measured resistance value is less than the judgment reference value (NO in step S4), it can be determined that the electrical insulation of the insulating sheet 8 is destroyed, and a warning is issued (step S5). On the other hand, if the measured resistance value is equal to or greater than the criterion value (YES in step S4), it can be determined that the electrical insulation of the insulating sheet 8 is ensured, and heat sealing is subsequently performed. Specifically, first, the switch 7 is opened (step S6), and the closed circuit for measuring the resistance value described above is also opened. At this time, the primary side circuit and the secondary side circuit of the transformer 2 are electrically separated.

Thereafter, power is supplied from the AC power supply 3 to the primary coil 21 by the controller 5, and power flows to the secondary coil 22 side by electromagnetic induction, causing the heater 4 to generate heat. The time required for heat-sealing the object to be sealed 10 is set in advance, and the power supply from the AC power supply 3 is automatically terminated after a predetermined time, and the heating of the heater 4 is also terminated (step S7). This completes the heat sealing. After step S5 or step S7 described above, the controller 5 raises the heater 4 together with the insulating sheet 8 (step S8). Thus, the electrical insulation of the heat sealer 1 is confirmed.

The heat sealer 1 in the electrical insulation confirmation method according to the present embodiment is arranged between the transformer 2, the heater 4 electrically connected to the secondary coil 22 of the transformer 2, and the heater 4 and the sealing object 10. It comprises an insulating sheet 8 and a mounting table 9 having a conductive surface 91 . Conductive surface 91 is electrically connected to reference potential G. FIG. Then, the heater 4 and the reference potential portion G are connected to each other in a state in which the heater 4 is brought into contact with the sealing object 10 placed on the conductive surface 91 through the insulating sheet 8 without supplying power to the primary coil 21 . is measured. The insulation of the insulating sheet 8 is confirmed based on the measured resistance value. Therefore, since the insulating property of the insulating sheet 8 can be reliably confirmed, it is possible to reliably avoid appearance defects and sealing defects of the heat-sealed object 10 . That is, even the object 10 to be sealed having electrical conductivity can be reliably heat-sealed.

In addition, in the present embodiment, the heat sealer 1 further includes a ohmmeter 6 connected between the secondary coil 22 and the reference potential section G, and a switch 7 electrically connected in series to the ohmmeter 6. I have it. The switch 7 is closed when the resistance value is measured, and is opened when the heater 4 is heated, that is, when heat sealing is performed. As a result, the safety of the device can be ensured by separating the primary side circuit and the secondary side circuit of the transformer 2 during heat sealing while measuring the above-described resistance value when checking the insulation.

Furthermore, in this embodiment, an insulating sheet 8 is attached to the heat sealer 1 so as to cover the heater 4 . Therefore, the insulating sheet 8 can be automatically interposed between the heater 4 and the object to be sealed 10 when confirming the insulation and when heat-sealing, and the efficiency of the work can be improved.

Here, according to the electrical insulation confirmation method according to the present embodiment, the heater 4 is brought into contact with the sealing object 10 through the insulating sheet 8, and the switch 7 is closed, and the resistance is measured by the ohmmeter 6. value is measured. Then, when the measured resistance value is equal to or higher than the reference value, the switch 7 is opened, the primary coil 21 is energized, the heater 4 is heated, and the object 10 to be sealed is heat-sealed. Therefore, when the insulating property of the insulating sheet 8 is confirmed and it is determined that the insulating property is ensured, the heat sealing operation can be started while the heater 4 is lowered. You can make your work more efficient.

The present disclosure is not limited to the above embodiments. For example, the electrically conductive sealing object 10 is limited to a shape that can sufficiently transmit the heat required for heat sealing, but is not limited to a sheet shape as in the above embodiment. Further, although the conductive sealing object 10 in the above embodiment is a sheet member made of a thermoplastic resin containing a conductive filler, it may be a CFRP sheet such as a CFRTP sheet.

1 Heat Sealer 2 Transformer 21 Primary Coil 22 Secondary Coil 3 AC Power Supply 4 Heater 6 Resistance Meter 7 Switch 8 Insulating Sheet 9 Mounting Table 91 Conductive Surface 10 Sealing Object G Reference Potential Part

Claims (4)

A method for checking electrical insulation of a heat sealer,
The heat sealer comprises a transformer having a primary coil and a secondary coil, a heater electrically connected to the secondary coil, and an insulating sheet disposed between the heater and a conductive sealing object; a mounting table having a conductive surface on which the object to be sealed is mounted;
the conductive surface of the mounting table is electrically connected to a reference potential portion of the heat sealer;
between the heater and the reference potential part in a state in which the heater is brought into contact with the sealing object placed on the conductive surface through the insulating sheet without supplying power to the primary coil; Measure the resistance of
A method for confirming electrical insulation of a heat sealer, wherein the insulation of the insulating sheet is confirmed based on the measured resistance value. The heat sealer
an ohmmeter for measuring the resistance value, connected between the secondary coil and the reference potential section;
a switch electrically connected in series with the ohmmeter,
2. The method of checking electrical insulation of a heat sealer according to claim 1, wherein said switch is closed when said resistance is measured, and said switch is opened when said heater is heated. 3. The method for confirming electrical insulation of a heat sealer according to claim 2, wherein said insulating sheet is attached to said heat sealer so as to cover said heater. The switch is opened when the resistance value measured by the ohmmeter in the state in which the heater is brought into contact with the sealing object through the insulating sheet and the switch is closed is equal to or greater than a reference value. 4. The method for confirming electrical insulation of a heat sealer according to claim 2, wherein the primary coil is energized to heat the heater to heat-seal the object to be sealed.

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