JP6795169B2 - Power plug manufacturing method and cord with power plug - Google Patents

Description

The present invention relates to a power plug manufacturing technique.

A cord with a power plug is generally manufactured by injection molding using a resin (thermoplastic resin) for the power plug body that protects the connection portion between the blade and the electric wire.
Conventionally, when a defect occurs in the power plug main body in the manufacturing process of a cord with a power plug, a production process is adopted in which this portion is cut and the remaining portion (cord or the like) is reused. However, since the total length of the cord with a power plug is limited in size, if it is less than this, it cannot be reused and will be disposed of.

As a method for preventing the occurrence of defects in the power plug body, for example, there is a manufacturing method disclosed in Patent Document 1. In this manufacturing method, each plug is attached to a holding member (also called a core, an insert, etc.) formed of a non-conductive synthetic resin, which has a position-determining portion that goes out from the synthetic resin forming the power plug body. The terminal (plug blade) is held to form the plug body. Since the holding member is fixed in the mold for molding by the position fixing portion 45 of the holding member, the holding member can be reliably positioned in the mold.

Further, in the method for manufacturing a power plug disclosed in Patent Document 2, an insulating resin (blade cap) and a core are integrally molded at the base of a blade to be inserted into an outlet, and the entire core is embedded and held. Mold the plug body as follows. As a result, it is not necessary to form a hole for attaching each plug blade to the core itself or a plug blade holding portion, and the manufacturing process can be simplified.

Japanese Unexamined Patent Publication No. 11-54192 JP-A-2010-205468

However, in the manufacturing method disclosed in Patent Document 1, the plug blade is inserted into the hole of the insert, and the positions in the vertical direction and the horizontal direction are determined. Further, the positioning in the height direction is fixed by sandwiching the plug blade with the insert. For example, if a locating hole (round hole) is formed in the plug blade, a pin for determining the height of the plug blade is provided in the mold for injection molding of the power plug body, and this pin is passed through the locating hole. The height of the plug blade can be positioned. However, since such a method cannot be adopted for a power plug that uses a plug blade without a locate hole, there is a problem that the manufacturing process, the mold to be used, etc. must be changed depending on the type of the plug blade. Remain.
In addition, when an operator sets a cord with an insert and a stopper blade in a mold when manufacturing the power plug body by injection molding, the cord itself is pulled by its own weight or tension, and the stopper blade itself becomes a power source. There is also a problem that defective products that do not meet the specified dimensions often occur because they move toward the inside of the plug body. Further, the plug blade itself may move toward the inside of the power plug body due to the pressure of the resin flowing in when the power plug body is manufactured by injection molding.
Even with the manufacturing method disclosed in Patent Document 2, the same problem as described above may occur when molding the core.

In addition, since the power plug body has a large resin wall thickness, appearance defects such as sink marks and welds often occur. In addition, in the case of a cord with a power plug, there is a problem that foreign matter (dust such as white powder and inclusions) lurking inside the cable and the cord often emerges on the surface during injection molding of the power plug body, resulting in poor appearance. Remains.

A main object of the present invention is to provide a method for manufacturing a power plug capable of more accurately positioning the height regardless of the type of the plug blade while preventing the occurrence of poor appearance. Further, a cord with a power plug manufactured by this manufacturing method is provided.

The present invention is a method for manufacturing a power plug, which is integrally molded with a resin so as to cover the insert in a state where the movement of the plug blade, which is partially projected from the surface of the insert and is arranged, is regulated by a regulating means. In the first molding step to be performed, the holes remaining when the regulating means is detached from the coated insert are filled with resin, and the resin is covered with the coated insert to form an outer layer portion. The first molding step comprises two molding steps, wherein a convex surface having a predetermined region is formed on the surface of the insert, and the plug blade projects from the convex surface. The insert is coated with a resin except for the convex surface of the insert, and in the second molding step, the resin is covered on the insert after the coating except for the convex surface to form the outer layer portion. It is characterized by doing.

Further, the cord with a power plug of the present invention is an insert in which a plug blade and a part of the cord connected to the plug blade are arranged, and a convex surface having a predetermined region on the surface of the insert. Is formed, the plug blade protrudes from the convex surface, and a part thereof protrudes from the convex surface of the insert, and the movement of the plug blade is regulated by the regulating means. A primary molded body integrally molded so as to cover the insert with a resin except for the convex surface of the insert, a hole remaining when the regulating means is separated from the primary molded body, and the convex portion. It is characterized by having an outer layer portion formed by covering the insert with a resin except for the surface.

According to the present invention, it is possible to more accurately position the height regardless of the type of the plug blade while preventing the occurrence of poor appearance in the manufacture of the power plug.

(A) to (d) are diagrams for explaining an example of the configuration of the cord with a power plug according to the present embodiment. (A) and (b) are diagrams for explaining an example of a primary molding process in a manufacturing process of a cord with a power plug. (A) to (d) are diagrams for explaining the state including the appearance of the primary molded body formed by the primary molding. (A) and (b) are diagrams for explaining an example of a secondary molding process in a manufacturing process of a cord with a power plug.

Hereinafter, embodiments will be described with reference to the drawings. The description will be given by taking as an example a case where the present invention is applied to a cord with a power plug (cable with a power plug) having an L-shaped power plug with a ground.

[Example of Embodiment]
FIG. 1 is a diagram for explaining an example of the configuration of a cord with a power plug according to the present embodiment. FIG. 1A is a diagram showing the appearance of the upper surface side of the cord 10 with a power plug, and FIG. 1D is a diagram showing the appearance of the cord 10 with a power plug 10 on the bottom surface side.
As shown in FIG. 1A, the cord 10 with a power plug includes a power plug 100 and a cord (cable) 101.

Further, FIG. 1B is a schematic vertical sectional view of the power plug 100 having a direction orthogonal to the center line (dashed line) shown in FIG. 1A and a cross section in the vicinity of the plug blade 200 described later. .. Further, FIG. 1 (c) is a schematic cross-sectional view of the power plug 100 having the center line (dashed line) shown in FIG. 1 (a) as a cross section. An example of the configuration of the cord 10 with a power plug will be described with reference to these figures.
The power plug 100 of the cord 10 with a power plug according to the present embodiment is the first injection molding (referred to as primary molding) and the second injection molding (referred to as secondary molding) performed after the primary molding. ) Is formed into a product shape through a total of two injection moldings. Details will be described later.

The power plug 100 includes an insert 102, a pair of plug blades 200, and a ground terminal 201. Further, each plug blade 200 and the ground terminal 201 are electrically connected to the electric wire 101a of the corresponding cord 101 (see FIG. 1C). Note that FIG. 1C shows, as an example, a state in which each plug blade 200, the ground terminal 201, and each electric wire 101a are connected by caulking.

The insert 102 is a member made of thermosetting resin, which is also called a core, and has a stopper blade 200, a hole (hole) having a predetermined shape for attaching the ground terminal 201, and a path for routing the electric wire 101a of the cord 101. Etc. are formed. By inserting the plug blade 200 and the ground terminal 201 into the holes of the insert 102, the positions in the vertical direction and the horizontal direction are defined as shown in FIG. 1D.
The surface of the insert 102 from which the plug blade 200 and the ground terminal 201 protrude is referred to as a front surface, and the back surface thereof is referred to as a back surface. In this case, the plug blade 200 and the ground terminal 201 are inserted into the holes from the back side of the insert 102, and each of them is set.

The insert 102 is also formed with a convex surface having a predetermined region on its surface. When the plug blade 200 and the ground terminal 201 are set on the insert 102, the plug blade 200 and the ground terminal 201 project outward from the convex surface.
Depending on the structure of the target product, a structure (fixing hole or groove) for preventing the insert 102 from falling out of the outlet due to an unexpected force may be provided on the convex surface of the insert 102.

The stopper blade 200 is formed in a substantially T shape as shown in FIG. 1 (b). As shown in FIG. 1B, each shoulder portion T of the plug blade 200 protruding outward is formed so as to be caught in the peripheral portion of the hole when the plug blade 200 is set on the insert 102. The shoulder portion T prevents the plug blade 200 from falling off from the insert 102 as it is in the insertion direction when the plug blade 200 is attached to the insert 102. The ground terminal 201 may be configured so that the same effect can be obtained.

The power plug 100 also includes a primary molded body 300 and a primary molded body 300 which are injection-molded so as to embed a part of the insert 102 and the cord 101 in a state where the plug blade 200 and the ground terminal 201 are set. It is configured to include an outer layer portion 400 that is covered so as to cover a predetermined area on the outer surface. The primary molded body 300 is formed by the above-mentioned primary molding, and the outer layer portion 400 is formed by the above-mentioned secondary molding. Although the diagonal lines representing the cross sections are omitted in FIGS. 1 (b) and 1 (c) for convenience of explanation, the internal space of the insert 102 is filled with a resin (thermoplastic resin) by the primary molding.
Hereinafter, the manufacturing process of the cord 10 with a power plug will be described.

FIG. 2 is a diagram for explaining an example of a primary molding step in the manufacturing process of the cord 10 with a power plug.
As shown in FIG. 2, the primary molded body 300 is molded using a molding die (upper mold A, lower mold B) for performing primary molding. Note that FIG. 2A is a schematic vertical sectional view in the same direction as FIG. 1B, and FIG. 2B is a schematic cross-sectional view in the same direction as FIG. 1C.

In the cavity of the upper mold A, a plug blade holding pin P for applying a predetermined pressing force to each of the plug blades 200 set in the insert 102 from the back surface side is arranged. In FIG. 2A, four plug blade holding pins P corresponding to the shoulder portions T of each of the pair of plug blades 200 are arranged. Further, the pressing force applied is sufficient to prevent the shoulder portion T of the stopper blade 200 from coming off from the back surface of the insert 102 when the resin is filled, which will be described later. Therefore, for example, the stopper blade pressing pin is applied to the shoulder portion T. The plug blade holding pin P may be fixed to the upper mold A after the one end of P is brought into contact with the mold A.

The lower mold B is formed with recesses having a depth and shape corresponding to the height and shape of the convex surface on the surface of the insert 102. Further, in this recess, the lengths of the plug blade 200 and the ground terminal 201 protruding from the convex surface of the insert 102 in the height direction (vertical direction when viewed from the front in FIGS. 1B and 1C) ( A hole having a depth and shape corresponding to the length of protrusion from the surface of the insert 102) and the shape is formed.

Since the stopper pin P is in contact with each of the shoulders T of the stopper blade 200 during the primary molding, the shoulder portion T of the stopper blade 200 is lifted off from the back surface of the insert 102 during the primary molding. Prevent it from being stolen. As described above, the plug blade holding pin P functions as a regulating means for regulating the change in the protruding length of the plug blade 200 from the surface of the insert 102, and the plug blade 200 can be positioned with high accuracy. Further, a holding pin for the ground terminal 201 may be provided so that the same effect can be obtained.
In addition to restricting the movement of the plug blade 200 by the plug blade holding pin P from the back side as described above, depending on the structure, the upper surface side or the lower surface side when the front surface of the insert 102 is the front side, etc. It can also be configured to regulate from one direction or multiple directions.

The insert 102 in which the plug blade 200, the ground terminal 201, etc. are arranged is housed in a predetermined position of the molding die, the upper mold A and the lower mold B are molded, and the molten resin (non-conductive) is contained in the cavity. A sex synthetic resin (such as vinyl chloride resin) is injected. In this way, in the primary molding which is the first molding step, the primary molded body 300 (insert 102 after coating with resin) is formed. As described above, in the primary molding, the other part except the surface of the insert 102 (the entire surface including the convex surface) is covered with resin, and the plug blade 200 and the ground terminal 201 are fixed to the insert 102 and integrally molded. ..

FIG. 3 is a diagram for explaining a state including the appearance of the primary molded body 300 formed by the primary molding.
FIG. 3A is a diagram showing the appearance of the upper surface side of the primary molded product 300, and FIG. 3D is a diagram showing the appearance of the bottom surface side of the primary molded product 300. Further, FIG. 3B is a schematic vertical sectional view of the primary molded body 300 having a direction orthogonal to the center line (dashed line) shown in FIG. 3A and a cross section in the vicinity of the plug blade 200 described later. Is. Further, FIG. 3C is a schematic cross-sectional view of the primary molded body 300 having the center line (dashed-dotted line) shown in FIG. 3A as a cross section.

As shown in 3 (a), (b), and (c), the primary molded body 300 after the primary molding has a hole portion (plug blade holding pin trace PH) generated when the plug blade holding pin P is detached. ) Remains, and there is a hole in the appearance. Further, when the foreign matter (dust such as white powder and inclusions) lurking inside the cable and the cord is not sufficiently removed, the foreign matter may be raised on the surface of the primary molded product 300. .. In addition, the thickness of the thermosetting resin may be large and sink marks, welds, etc. may occur.

However, the cord 10 with a power plug according to the present embodiment forms the cord 10 with a power plug by subjecting the primary molded body 300 that has been primarily molded to secondary molding for adjusting the appearance thereof. Therefore, the cause of poor appearance of the primary molded product 300 as described above is eliminated at the time of secondary molding, so that the cord 10 with a power plug formed in the product shape has a poor appearance (sink, weld, foreign matter mixed). It can be prevented from being lost.
Hereinafter, the secondary molding process in the manufacturing process of the cord 10 with the power plug will be described.

FIG. 4 is a diagram for explaining an example of a secondary molding step in the manufacturing process of the cord 10 with a power plug.
As shown in FIG. 4, the power plug 100 is molded using a molding die (upper mold C, lower mold D) for performing secondary molding. Note that FIG. 4A is a schematic vertical sectional view in the same direction as FIG. 1B, and FIG. 4B is a schematic cross-sectional view in the same direction as FIG. 1C.

A cavity is formed in the upper mold C so that an outer layer portion 400 having a predetermined thickness can be covered in a predetermined region on the outer surface of the primary molded body 300 as shown in FIGS. 4A and 4B. Has been done. As shown in FIGS. 4A and 4B, since the resin invades and fills the stopper blade holding pin trace PH in the secondary molding, the hole of the stopper blade holding pin trace PH is also closed. It disappears from the outside.

The lower mold D has a length (insert 102) in the height direction (vertical direction when viewed from the front in FIGS. 1B and 1C) of the plug blade 200 and the ground terminal 201 protruding from the surface of the insert 102. A hole formed with a depth and shape corresponding to the length) and shape corresponding to the surface of the hole is formed.
As shown in FIG. 4B, the resin penetrates into the surface region other than the convex surface on the surface of the insert 102 by the secondary molding. In this way, the resin is covered on the surface of the insert 102 excluding the convex surface to form the outer layer portion 400. Therefore, in the power plug 100 after the secondary molding, the plug blade 200 and the ground terminal 201 project. Becomes flat.

The primary molded body 300 is housed in a predetermined position, the upper mold C and the lower mold D are molded, and the molten resin is injected into the cavity. In this way, in the secondary molding which is the second molding step, the cord 10 with the power plug is formed into the product shape (finished product).
In the secondary molding, since the primary molded body 300 formed in advance is coated with resin, the outer layer portion 400 can be thinned, so that molding defects such as sink marks and welds can be improved. Become.
Further, since the peripheral edge of the surface of the insert 102 is covered by the outer layer portion 400, for example, when the cord 10 with the power plug is used, the primary molded body 300 (the insert 102 after coating with resin) does not fall off from the power plug 100. , The user can safely use the cord 10 with a power plug.

As described above, the cord 10 with the power plug according to the present actual embodiment is effectively suppressed from the occurrence of the appearance defect and the occurrence of the height dimension defect of the plug blade by going through the manufacturing process of the primary and secondary molding. It becomes a product.
As a result, it is possible to solve the poor appearance of the power plug body (sink, weld, foreign matter mixed) and the height dimension of the plug blade, so the man-hours and costs required for reproduction and the defective products to be disposed of are It will be a reduction. Further, since the foreign matter is contained in the first injection molding without removing the foreign matter lurking inside the cable and the cord, it is possible to eliminate the burden on the operator and the variation due to the skill.

The present invention is a cable with a charging plug used in an electric vehicle, a hybrid vehicle, etc., or a cord and a cord with a power plug used for supplying electric power to an electric appliance such as an IH cookware or a microwave oven. It can also be applied to the manufacture of cables with plugs for DC power supply that supply power to servers in data centers.

Further, in the present invention, the same effect can be obtained for a plug blade having a locating hole, a thermosetting resin for a plug body having a large wall thickness, a sink mark, a weld, or the like, which tends to cause poor appearance. ..

In addition, although the countermeasures against the appearance defect of the power plug body and the height dimension defect of the plug blade have been explained, the present invention is not limited to this. For example, when the amount of thermoplastic resin used for the power plug body is large, the mold clamping force of the injection molding machine used for production and the limitation of the injection capacity have a great influence, and when purchasing a large molding machine for production. There is also. However, by forming a structure in which the portion molded by the thermoplastic resin is divided into a plurality of parts as in the present invention, the mold clamping force can be reduced and the injection capacity can be reduced. As a result, it is possible to manufacture without purchasing a large injection molding machine, so that it is possible to reduce the manufacturing cost.

The embodiments described above are for more specific explanation of the present invention, and the scope of the present invention is not limited to these examples.

10 ... Cord with power plug, 100 ... Power plug, 101 ... Cord (cable), 101a ... Electric wire, 102 ... Insert, 200 ... Plug blade, 201 ... Earth terminal , 300 ... Primary molded body, 400 ... Exterior part.

Claims (4)

It is a manufacturing method of power plugs.
The first molding step of integrally molding with a resin so as to cover the insert in a state where the movement of the plug blade disposed so as to project a part from the surface of the insert is regulated by the regulating means.
A second molding step is provided in which the holes remaining when the regulating means is detached from the coated insert are filled with resin, and the resin is covered with the coated insert to form an outer layer portion. And
A convex surface having a predetermined region is formed on the surface of the insert, and the plug blade projects from the convex surface.
In the first molding step, the insert is coated with a resin except for the convex surface of the insert.
The second molding step is characterized in that the outer layer portion is formed by covering the insert after coating with a resin except for the convex surface.
How to make a power plug. The regulating means is characterized in that the movement of the plug blade, which is disposed so as to project a part from the convex surface of the insert, is regulated from at least one direction of the back surface side, the upper surface side, and the lower surface side. To do,
The method for manufacturing a power plug according to claim 1. An insert in which a plug blade and a part of a cord connected to the plug blade are arranged, and a convex surface having a predetermined region is formed on the surface of the insert, and from the convex surface. The plug blade is protruding,
The insert is integrally covered with resin except for the convex surface of the insert in a state where the movement of the plug blade, which is partially projected from the convex surface of the insert, is regulated by the regulating means. The molded primary molded body and
It is characterized by having a hole portion remaining when the regulating means is separated from the primary molded body, and an outer layer portion formed by covering the insert after coating with a resin except for the convex portion surface. To
Cord with power plug. In the primary molded body, the regulating means causes the movement of the plug blade, in which a part thereof protrudes from the convex surface of the insert, from at least one direction of the back surface side, the upper surface side, and the lower surface side. It is characterized by being regulated and molded,
The cord with a power plug according to claim 3.

Images