JP2006324513A - Method for forming protective film for resistor having lead wire and apparatus for forming protective film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for forming a protective film for a resistor having lead wires which can form the reliable protective film through once coating and can easily reduce its production cost, and also to provide an apparatus for forming protective film. <P>SOLUTION: Lead wires 4 are fixed to metallic caps 3 of a not-coated main body 1 fitted on both ends of a resistor element 2, the lead wires 4 supplied onto a support 9 from a transfer chain 6 are compressed by a belt 11 from its upper side, and the lead wires 4 are rolled on the support 9 by the driving force of the belt 11 to forcibly rotate the main body 1. In the course of or immediately before this forcible rotating step, a step of applying a coating 12 on the surface of the main body 1 with the use of a coating roller 14 is carried out, and the coating is thermally set in a dryer 8 to form a protective film 5. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a resistor with a lead wire provided with a substantially cylindrical main body portion in which a metal cap is fitted to both ends of the resistor element, and a lead wire fixed to the cap of the main body portion. The present invention also relates to a method for forming a protective film provided on the surface of an unpainted main body and a protective film forming apparatus.

  In the manufacturing process of this type of resistor with a lead wire, a metal cap is fitted to both ends of the resistor element to form an unpainted main body portion, and further extends outward concentrically with the main body portion. Then, after the lead wires are fixed to the caps, a protective film is formed on the surface of the main body while supporting and transporting the lead wires.

As a general method for forming such a protective film, a roller coating method in which a coating material is applied to the surface of a main body portion of a resistor supplied by a transport chain using an application roller (for example, a patent) Reference 1). In this roller coating method, the coating roller to which the paint in the tank is attached is rotated and pressed against the main body of the resistor in the transport path, so that the protective film is applied to the surface of the main body. This is a coating method, and the resistor after coating is transferred to a drying furnace in order to thermally cure the paint. In this case, since the uncured paint applied to the main body part of the resistor tends to flow downward due to its own weight, it is not possible to form a coating film with a substantially uniform required thickness on the surface of the main body part in one application process. Therefore, the process of applying and drying the coating material for the protective film was performed two to three times.
JP-A-9-10660 (2nd page)

  In the above-described conventional technology, it is necessary to perform the process of applying the protective film paint and drying it several times during the manufacturing process of the resistor with the lead wire, so the manufacturing time required for forming the protective film is prolonged. There was a problem that it was difficult to reduce the cost. In addition, when the viscosity of the coating material for the protective film is high, the coating process does not spread over the step between the resistor element and the cap in the coating process, so that a gap is easily formed. As a result, there is a possibility that pinholes are generated and the reliability is impaired.

  The present invention has been made in view of such a state of the art, and a first object of the present invention is to provide a lead wire with which a highly reliable protective film can be formed by a single coating, which can easily reduce the manufacturing cost. The object is to provide a method for forming a protective film of a resistor. A second object of the present invention is to provide a protective film forming apparatus for a resistor with a lead wire, which can form a highly reliable protective film by a single coating process and can easily reduce the manufacturing cost.

  In order to achieve the first object described above, the method for forming a protective film for a resistor with a lead wire according to the present invention comprises an unpainted main body portion formed by fitting metal caps at both ends of a resistor element. In the manufacturing process of the resistor with lead wires, the lead wires are fixed to the caps of the main body portion, and a protective film is formed on the surface of the main body portion while supporting and transporting the lead wires. A forcible rotation step for forcibly rotating the main body portion by rolling the wire along the conveying direction, an application step for applying paint to the surface of the main body portion by an application roller, and a surface of the main body portion. And a drying step in which the applied paint is thermally cured to form the protective film, and the coating step is performed during or immediately before the forced rotation step.

  According to such a protective film forming method, since the resistor is forcibly rotated after the coating material for the protective film is applied by the application roller, the required thickness is substantially uniform on the surface of the main body portion in one application process. In addition, it is difficult to form gaps that cause pinholes even when the viscosity of the paint is high, and a highly reliable protective film can be formed by thermally curing the paint film in the drying step. Therefore, the work time required for forming the protective film of the resistor with lead wire is greatly shortened, and the manufacturing cost can be reduced.

  In the above protective film forming method, in the forced rotation step, a lead wire is mounted on a support extending along the transport direction, and a belt is pressed against the lead wire from above, and the belt is moved in the transport direction. It is preferable that the lead wire rolls on the support by being driven along, because a mechanism for efficiently forcibly rotating the lead wire after the coating process by the required number of times can be simplified.

  Also, in the above protective film forming method, if the main body part is forcibly rotated through the lead wire even in the initial stage of the drying process, until the coating film on the surface of the main body part is thermally cured to some extent Since forced rotation is performed, it is preferable that there is no possibility of uneven film thickness due to the weight of the paint in the initial stage of the drying process.

  In order to achieve the second object described above, in the present invention, after fixing the lead wires to the caps of the unpainted body part in which metal caps are fitted to both ends of the resistor element, In a protective film forming apparatus for a resistor with a lead wire that forms a protective film on the surface of the main body portion while supporting and transporting these lead wires, a support body extending along the transport direction, and a support body on the support body An endless belt driven to move along the conveying direction, and an application roller for applying paint to the surface of the main body portion, and the lead wire mounted on the support is By rolling with a belt driving force, the main body portion is forcibly rotated, and paint is applied to the surface of the main body portion by the application roller during or immediately before the forced rotation operation. Yo It was constructed in.

  According to the protective film forming apparatus configured as described above, the lead wire of the resistor supplied onto the support can be reliably rolled on the support by the driving force of the belt, and the moving speed of the belt can also be increased. Since it can be easily adjusted, the lead wire after the coating process can be efficiently and forcibly rotated as many times as necessary by a simple mechanism. Therefore, it is possible to form a coating film with a substantially uniform required thickness on the surface of the main body portion in a single coating process, and even if the viscosity of the paint is high, it is difficult to generate gaps that cause pinholes. A highly reliable protective film can be formed by thermally curing the film in a drying step. Therefore, the work time required for forming the protective film of the resistor with lead wire is greatly shortened, and the manufacturing cost can be reduced.

  In the above configuration, when the support body is disposed outside the conveyance path of the main body portion, and the portion near the base end of the lead wire is mounted on the support body, the driving force of the belt is applied to the main body portion. Since it can be applied to the lead wire in the vicinity, it is preferable that the main body portion can be forcibly rotated more easily than when a driving force is applied to a portion near the tip of the lead wire.

  According to the method for forming a protective film for a resistor with a lead wire according to the present invention, since the resistor is forcibly rotated after the coating material for the protective film is applied by the application roller, the surface of the main body portion is substantially removed in one application process. A coating having a uniform required thickness can be formed, and even when the viscosity of the coating is high, a gap that causes pinholes is less likely to occur. Therefore, a highly reliable protective film can be formed in a short time, which greatly contributes to the reduction of the manufacturing cost of the resistor with lead wire.

  In addition, the protective film forming apparatus for a resistor with a lead wire according to the present invention uses a simple mechanism that rolls the lead wire of the resistor supplied onto the support by the driving force of the belt, and then the lead wire after the coating process. Can be forcibly rotated as many times as necessary, so that a coating film having a substantially uniform required thickness can be formed on the surface of the main body in a single coating process, and even if the viscosity of the paint is high, It becomes hard to produce the gap which becomes a factor. Therefore, a highly reliable protective film can be formed in a short time, which greatly contributes to the reduction of the manufacturing cost of the resistor with lead wire.

  BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partially sectional front view of a resistor with a lead wire according to an embodiment of the present invention, and FIG. 2 is a sectional view of the resistor before forming a protective film. FIG. 3 is an explanatory view schematically showing the protective film manufacturing process of the resistor, and FIG. 4 is an explanatory view showing the coating process by the protective film forming apparatus in FIG. 3 from the front side.

  The resistor shown in FIG. 1 includes a substantially cylindrical main body portion 1 in which metal caps 3 are fitted to both ends of a resistor element 2 and a pair of main body portions 1 fixed to both caps 3. The lead wire 4 and the protective film 5 formed on the surface of the main body portion 1 are configured. When manufacturing this resistor, caps 3 are fitted to both ends of the resistor element 2 by press fitting or the like, and then spiral grooves and trimming grooves (not shown) are formed on the outer peripheral surface of the resistor element 2. Then, by adjusting the resistance value, the main body portion 1 having predetermined electrical characteristics is obtained. Next, lead wires 4 are fixed to both caps 3 by welding or soldering so as to extend outward concentrically with the main body portion 1 to obtain an unpainted resistor as shown in FIG. . After that, as shown in FIG. 3, the lead wire 4 is supported by the transport chain 6 and transported, and uncoated resistors are sequentially supplied to the protective film forming device 7 and the drying furnace 8, thereby A protective film 5 is formed on the surface to obtain a resistor as shown in FIG. A pair of transport chains 6 are arranged in parallel and move in the direction of arrow A in FIG. 3, and the lead wires 4 of the resistors are supported on the respective transport chains 6.

  The manufacturing process for forming the protective film 5 on the surface of the main body part 1 will be described in detail. This protective film manufacturing process is performed in parallel with the forced rotation process for forcibly rotating the main body part 1 and the initial stage of the forced rotation process. A coating film formed on the surface of the main body portion 1 in the forced rotation process and the coating process is thermally cured in the drying process by distinguishing between the coating process performed and the drying process performed after completion of the forced rotation process. 5 is formed. As shown in FIG. 3, the protective film forming apparatus 7 includes an endless body wound around a support body 9 extending along the transport direction (arrow A direction) and a driving roller 10 rotating in the arrow B direction. A belt 11, a paint can 13 filled with a paint 12, and an application roller 14 for applying the paint 12 in the paint can 13 to the surface of the main body 1. The lead wire 4 is supplied to the body 9.

  In the forced rotation process, the belt 11 is pressed from above onto the lead wire 4 of the resistor supplied from the transport chain 6 onto the support body 9, and the lead wire 4 is transported on the support body 9 by the driving force of the belt 11. The main body portion 1 is forcibly rotated by rolling along. As shown in FIG. 3, the support 9 is provided with an inclined surface 9a on the upstream side, and when the lead wire 4 conveyed by the conveying chain 6 reaches the inclined surface 9a, it is smoothly guided onto the support 9. It is like that. Further, as shown in FIG. 4, since the pair of support bodies 9 are arranged in parallel inside the pair of transport chains 6, a portion near the base end of the lead wire 4 is mounted on the support body 9. A driving force is applied from the belt 11. When the driving force of the belt 11 is applied to the lead wire 4 in the vicinity of the main body portion 1 in this way, the main body portion 1 is made to be more in comparison with the case where the driving force is applied to a portion near the tip of the lead wire 4. It can be easily forced to rotate. Although not shown in the drawings, in the present embodiment, a preheating operation for heating the main body portion 1 with a warm air heater or the like is performed prior to the forced rotation step. The adhesion of the paint 12 can be improved.

The coating process is performed as soon as the lead wire 4 starts rolling on the support 9, and as shown in FIGS. 3 and 4, the liquid in the paint can 13 is applied by the coating roller 14 rotating in the direction of arrow C. The paint 12 is applied (transferred) to the surface of the main body portion 1. At this time, the main body portion 1 is applied with the paint 12 while being forcibly rotated, and is continuously forcibly rotated after the application, so that the paint 12 spreads over the surface of the main body portion 1 evenly. Therefore, it is possible to form a coating film (uncured protective film) having a substantially uniform required thickness on the surface of the main body portion 1, and a gap that causes pinholes even if the viscosity of the paint 12 is high. The risk of occurrence is low. In addition, although the material of the coating material 12 can be suitably selected in consideration of various conditions such as moisture resistance required for the protective film 5, in this embodiment, the one-component epoxy resin is SiO ₂ that is a filler. Is used as the paint 12. Here, if the content of SiO ₂ (filler) is 15% or less, the moisture resistance is significantly deteriorated, which is not preferable.

  The drying process is performed in the drying furnace 8. As shown in FIG. 3, in the vicinity of the entrance in the drying furnace 8, it is wound around a driving roller 15 that rotates in the direction of arrow D and is pressed against the lead wire 4. An endless belt 16 is disposed, and the main body portion 1 is forcibly rotated by causing the belt 16 to roll the lead wire 4 along the conveying direction in the initial stage of the drying process. That is, a resistor having a coating film having a substantially uniform required thickness formed on the surface of the main body portion 1 by the protective film forming device 7 is supplied into the drying furnace 8 by the transport chain 6. Although the protective film 5 is formed by thermally curing the coating film (paint 12), there is a possibility that the film thickness may be uneven due to its own weight while the paint 12 is uncured. Therefore, in this embodiment, a belt 16 is disposed near the entrance in the drying furnace 8 in order to roll the lead wire 4 in the preheating stage immediately after the start of the drying process, and the coating film on the surface of the main body portion 1 has a certain degree. Forced rotation is performed until thermosetting. This eliminates the possibility of unevenness in the film thickness due to the weight of the paint 12 in the initial stage of the drying process. Therefore, when the coating film formed by the protective film forming device 7 is cured in the drying furnace 8, the desired thickness The protective film 5 is formed.

  As described above, in the method for forming a protective film for a resistor with a lead wire according to this embodiment, after the coating material 12 for the protective film 5 is applied by the application roller 14, the resistor is forcibly rotated by the driving force of the belt 11. Therefore, a coating film having a substantially uniform required thickness can be formed on the surface of the main body portion 1 in a single coating process, and even if the viscosity of the paint 12 is high, gaps that cause pinholes are unlikely to occur. A highly reliable protective film 5 can be formed by thermally curing the film in a drying step. Therefore, the working time required for forming the protective film 5 of the resistor with lead wire is greatly shortened, and the manufacturing cost can be reduced.

  The protective film forming apparatus 7 used in the manufacturing process of the protective film 5 in the present embodiment is driven by pressing the belt 11 against the lead wire 4 of the resistor supplied from the transport chain 6 onto the support 9. Therefore, not only can the lead wire 4 be reliably rolled on the support 9 by the driving force of the belt 11, but also the adjustment of the moving speed of the belt 11 is easy. Therefore, the lead film 4 after the coating process can be efficiently forcibly rotated as many times as necessary by a simple mechanism, and the above-described protective film formation in which the highly reliable protective film 5 is formed in one coating process. Suitable for the method.

It is a partial cross section front view of the resistor with a lead wire concerning the example of an embodiment of the present invention. It is sectional drawing before protective film formation of this resistor. It is explanatory drawing which shows typically the protective film manufacturing process of this resistor. It is explanatory drawing which shows the application | coating process by the protective film formation apparatus in FIG. 3 from the front side.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Main-body part 2 Resistor element 3 Cap 4 Lead wire 5 Protective film 6 Conveyance chain 7 Protective film forming apparatus 8 Drying furnace 9 Support body 10 Drive roller 11 Belt 12 Paint 13 Paint can 14 Application roller 15 Drive roller 16 Belt

Claims (5)

An unpainted body part is formed by fitting metal caps on both ends of the resistor element. After fixing lead wires to the caps of the body part, the lead wires are supported and transported. While in the process of manufacturing a resistor with lead wire that forms a protective film on the surface of the body part,
A forced rotation step of forcibly rotating the main body portion by rolling the lead wire along the conveying direction;
An application step of applying a paint to the surface of the body portion by an application roller;
Including a drying step of thermally curing a paint applied to the surface of the main body portion to form the protective film,
A method of forming a protective film for a resistor with a lead wire, wherein the coating step is performed during or immediately before the forced rotation step.   2. The forced rotation process according to claim 1, wherein the lead wire is mounted on a support member extending along the transport direction, a belt is pressed against the lead wire from above, and the belt is transported in the transport direction. A method of forming a protective film for a resistor with a lead wire, wherein the lead wire rolls on the support by being driven along.   3. The method of forming a protective film for a resistor with a lead wire according to claim 1, wherein the main body portion is forcibly rotated through the lead wire even in an initial stage of the drying step. . After fixing lead wires to both caps of the unpainted body part with metal caps fitted to both ends of the resistor element, the lead part is supported and transported while protecting the surface of the body part A protective film forming apparatus for a resistor with a lead wire for forming a film,
A support extending along the transport direction, an endless belt driven to move along the transport direction on the support, and an application for applying paint to the surface of the main body portion With rollers,
By rolling the lead wire mounted on the support with the belt driving force, the main body portion is forcibly rotated, and the coating roller is used during or immediately before the forced rotation operation. A protective film forming apparatus for a resistor with a lead wire, wherein a coating material is applied to a surface of the main body portion.   5. The lead according to claim 4, wherein the support is disposed outside a transport path of the main body portion, and a portion near the proximal end of the lead wire is mounted on the support. Protection film forming device for resistors with wires.

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