JP3329141B2 - Manufacturing method of mold transformer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a mold transformer used for various electronic devices.

[0002]

2. Description of the Related Art In recent years, transformers used in various electronic devices have been required to have higher performance such as high safety, high reliability, small size and light weight, high efficiency and low heat generation. A method of molding the entire transformer with a synthetic resin has been developed.

Hereinafter, a conventional mold transformer will be described with reference to FIGS.

In FIGS. 13 and 14, a bobbin 1 having a flange 2 at both ends and a flange 7 at the center is provided with several grooves 3 for winding a coil 4 and passing a lead wire 5 through the groove 3 in the air. 2 is connected to the terminal 6 along the side surface, the E-shaped laminated core 8 is inserted into the center hole 9 of the bobbin 1, the I-shaped laminated core 10 is incorporated, and the butt joint 11 is welded to form the transformer body 12. As shown in FIG. 15, a core positioning pin 14 is held in a mold 13 and molded from a gate 15 with a molding resin 16 made of a thermoplastic resin to form a molding transformer 17 as shown in FIG. .

[0005]

However, in the above configuration, first, the position of the gate 15 is in the same direction as the laminating direction of the E-type and I-type laminated cores 8 and 10, and the gate 15 is moved by the injection pressure. Type, I type laminated core 8,1
No. 0, the mold resin 16 quickly rotates around the both ends, and the both ends of the core are compressed, deteriorating the insulating properties of the magnetic coating on the surface of the laminated core, or the E-shaped laminated core 8.
In this case, the joint between the midfoot portion 18 and the I-type laminated core 10 was shifted, the magnetic loss was increased, and the characteristics of no-load current and no-load loss were deteriorated. In addition, there was a problem of core deformation and displacement in the core laminating direction.

Further, the tip of the core positioning pin 14 in the mold 13 is cylindrical, and this portion becomes a space as a round hole after molding, and the core of the mold transformer 17 is exposed as an external appearance. As the number of holes 20 is larger, the larger the hole diameter is, the more moisture enters from the outside, so that there is a problem that the reliability of the waterproof insulation performance is reduced.

Further, as shown in FIGS. 17 to 19, clearances A and B between the flange 2 of the bobbin 1 and the E-type and I-type laminated cores 8 and 10 are not large enough in structure, and are about 0.3 mm. In addition, during molding, resin filling cannot be performed cleanly due to variations in molding conditions and the like. Therefore, it has been difficult to secure stable insulation sealing performance such as withstand voltage deterioration between the end face of the coil 4 and the core.

As shown in FIG. 20, the lead wire 5 of the coil 4 wound around the bobbin 1 passes obliquely through the space of the groove 3 without any intervention, and is connected to the terminal 6 along the side surface of the bobbin flange 2. After being wound and connected, and then molded, it is particularly preferable that the thickness be 0.1 mm.
In the case of a thin wire having a diameter of about 12 mm or less, there is a problem that the wire is broken in several cycles due to the temperature shrinkage of the resin in the heat cycle test even if the wire is broken during molding or there is no break during molding.

In the case where the structure of the mold 13 is two-way up and down as shown in FIG. 21, there are some thermoplastic mold resins 16 having poor releasability depending on the material thereof, and molding conditions such as mold temperature. Due to the change, when the mold is opened after the completion of the molding, there is a phenomenon that the transformer is hardly attached to the inside of the movable-side mold 21, and it is necessary to cool the transformer with air or take out a measure by applying vibration. In addition, the workability deteriorates and the resin stays in the molding machine cylinder during that time, so there is a loss of purging and reworking.

In addition, when molding the transformer main body, the volume of the metal portion such as the core and coil is large, and in the case of the thermoplastic resin mold, there is a concern that crack failure may occur in a heat cycle test due to a difference in linear expansion coefficient between the metal and the resin. Recently, about -40 ° C. to 120 ° C., 1 h each, and about 200 cycles are required, the temperature range is wide, and it is very difficult to select a thermoplastic resin which is cost and performance-friendly.

The present invention solves the above-mentioned problems, and provides a mold transformer made of a thermoplastic resin which realizes high safety, high reliability, high efficiency, and streamlining of processes.

[0012]

Means for Solving the Problems The method of manufacturing a mold transformer according to the present invention in order to solve the above problems, mold growth
The molding process involves laminating the mold on the side of the transformer body.
Inject mold resin that opens downward from the core
A gate to mold, and mold resin from the gate
This is a method of injecting into a mold and molding.

[0013]

As described above, the molding process is performed by the transformer.
In the mold on the side of the body, below the laminate core
Provide a gate to inject the mold resin opened toward
Mold resin is injected into the mold from the gate and molded, so that no resin pressure is applied directly in the core lamination direction. Resin pressure is applied to the joint and stress acts in the direction of compressing the gap, so magnetic efficiency is improved, no-load current and no-load loss are reduced compared to before molding, and resin pressure on the core lamination is evenly distributed. It is dispersed small and does not cause core deformation or displacement.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method for manufacturing a mold transformer of the present invention will be described.
Illustrating an embodiment of the FIGS.

[0015] When the prior art the same parts are denoted by the same reference numbers, keep the drawing, when forming the center hole 26
Both form a collar 22 at both ends and a central collar 23,
A plurality of terminals 6 are implanted at the lower end of
A groove 25 is formed in the collar 22 between the elements 6 to form a bobbin 24
Bobbin forming step, and a coil
Coil winding step of winding 4 and lead wire of coil 4
5 along the inner wall of the groove 25 and the surface of the collar 22
And the lead wire wiring work in which the lead wire 5 is wired to the terminal 6
And the middle foot of the E-shaped laminated core of the E-shaped laminated core 8
Insert the part 18 into the center hole 26 of the bobbin,
The core 8 and the I-shaped laminated core 10 are shaped like a sun.
Layered and assembled into bobbin 24
A Butt joint 11 between 8 and I-shaped laminated core 10
Transformer body shape in which transformer body 27 is formed by welding
Forming step, movable mold 28a and fixed mold
The core positioning pins 29 and 34 are provided.
The transformer main body 27 is held in the
Made of thermoplastic resin in the mold 28
Mold molded by injecting mold resin 16
And a molding step.

At this time, the molding step includes a transformer.
E-type laminate is applied to the mold 28 on the side of the main body 27.
The core 8 and the I-shaped laminated core 10 are opened downward.
A gate 30 for injecting the molded resin 16 is provided.
Mold resin 16 from gate 30 into mold 28
And molding.

As a result, the molding resin 16 becomes E-shaped and I-shaped.
It does not directly contact the mold laminate cores 8 and 10, but flows in a well-balanced manner along the coil winding direction from the core outer peripheral portion 32 of the transformer main body 27 or the clearance C between the core and the coil 4 and does not quickly fill both ends of the core laminate. Core outer periphery 3
2, and the coil outer peripheral portion 33 is finally filled.

As a result, the pressure of the mold resin does not compress the laminated portion of the core, the insulating property of the magnetic coating on the core surface does not deteriorate, and the joint portion between the middle foot portion 18 of the E-shaped laminated core and the I-shaped laminated core 10 is compressed. Therefore, the bonding gap is reduced by the pressurization, and the magnetic efficiency of the transformer is improved.

Further, the E-type and I-type laminated cores 8 and 10 of the transformer main body 27 are positioned at the center in the mold 28 so that the mold resin 16 can be filled into the inside and the outside of the transformer main body 27 with a uniform thickness. a core and a positioning pin 29 provided, the fixed mold 28b of a mold 28
Are provided with a plurality of spring-embedded pins 34 so that even when the core lamination dimension varies by about 1 mm during initial mold clamping, it does not shift.

The movable mold 28a is provided with at least six fixed pins 29 at substantially equal intervals with respect to the entire circumference of the core. By setting the number to six or more, the load balance by the resin pressure on the core is stabilized, and the core deformation can be prevented.

The transformer body 27 is pushed in the direction of the movable mold 28a by the molding resin 16 by the above-described setting of the gate position and the core positioning pins, but the movement is stopped by the fixed positioning pins 29, and a uniform resin thickness is secured. Is done. As shown in FIGS. 4 and 5, the positions of the core positioning pins 29 and 34 should be relatively balanced vertically so as to achieve a good weight balance.

FIGS. 4 and 5 show a pin trace 29a formed by the fixed pin 29 and a spring-embedded pin trace 34a.

Also, as shown in FIG.
As a development example of the tip shape of the core positioning pins 29 and 34 in 8, it is also possible to set such as a substantially spherical core positioning pin 35 and a substantially conical core positioning pin 36. Thereby, when the mold is formed, the exposed area of the core surface can be made extremely small.

As shown in FIGS. 7 to 9, an example of the shape of the tip of the flange 22 at both ends of the bobbin 24 is an E-shape.
An E-type laminate core is provided so that the mold resin 16 can be filled around the clearance portions D and E (shown in FIG. 7) which contact the I-type laminate cores 8 and 10 during molding.
(A) The surfaces of the flanges 22 at both ends facing the I-type laminate core
And an E-type laminate core and an I-type laminate core
A concave step 37 with a dimension longer than
Terminal facing the lower surface of the I-type laminated core
A recess 38 is provided in the implanted collar 22 . It is generally necessary to set the step size (filled thickness size) to about 0.5 mm or more. Thereby, a stable insulation clearance dimension between the coil and the core can be secured.

As shown in FIG. 10, in the shape of the groove 25 of the terminal pin planting block of the flange 22 of the bobbin 24, a substantially tapered notch 43 is provided on the surface of the coil 4, and the coil lead wire 5 The wiring is routed along the inner wall surface 44 and the side wall 45 of the flange 22 and connected to the terminal 6 to incorporate the E-type and I-type laminate cores 8 and 10 to form a transformer main body, which is molded. The position of the terminal 6 and the position of the groove 25 coincide with the direction in which the lead wire 5 is routed, and the lead wire 5 is connected to the inner wall surface 44 of the groove 25 and the bobbin flange 22.
Is set so as to be sandwiched between the surface of the side wall 45 and the molding resin to be molded later.

FIGS. 11 to 12 show another embodiment of the present invention, in which a stationary mold 28b is machined. Of the mold transformer 41 in which the convex portions 40 are formed. The protrusion height of the convex portion 40 is about 0.05 to 0.1 mm, whereby
After completion of the molding, the movable mold 28a moves smoothly without the mold transformer 41, and the mold transformer 41 remaining in the fixed mold 28b is forcibly pushed up by the ejector pins 42 in the mold. Can be taken out.

The material of the thermoplastic resin 16 which is a mold material used in each of the above embodiments has the performance of lowering the crystallization start temperature and increasing the recrystallization temperature to lower the crystallization speed. In addition, it is desirable for the mold transformer to select a molding resin having a performance in which the linear expansion rate and the shrinkage rate after temperature of the resin are made substantially equal to each other, and to form them by molding. Specifically, the insulation class of the transformer is class A ~
In the case of class E, a temperature guarantee of 100 ° C to 115 ° C is required.

Therefore, assuming that the temperature range of the heat cycle test is −40 ° C. to 120 ° C., the crystallization onset temperature is 2
00 ° C to 220 ° C, recrystallization temperature 100 ° C to 120 ° C,
Shrinkage after temperature is about 0.3% at 120 ° C, and linear expansion rate is 16
A resin having a performance of about 0.3% in a temperature range of 0 ° C. is preferable. 12
At a high temperature near 0 ° C., the elongation due to the linear expansion coefficient and the post-shrinkage cancel each other out, which leads to prevention of cracks during a heat cycle. Therefore, it can be said that a resin that does not sufficiently crystallize immediately after molding and can secure sufficient strength is preferable.

For example, even with the same thermoplastic resin, it is more effective to use glass-reinforced PET resin (crystallinity: 30 to 40%) than 66 nylon or PBT resin. Of course,
It can be used not only as a molding material but also as a bobbin molding material.

[0030]

As described above, according to the method for manufacturing a mold transformer of the present invention, the molding step is performed on the side of the transformer body.
Open the mold toward the bottom of the laminate core.
Provide a gate to inject the mold resin
By adopting a method in which a resin is injected from a gate into a mold and molded, the magnetic efficiency of the transformer is improved by utilizing the pressure of the mold resin.

Further, the core positioning pin in the mold is formed by molding the fixed side mold as a spring embedded type, and the movable mold side as at least six or more fixed pins at substantially equal intervals. In other words, there is no core deformation or core displacement at the time of molding, and there is no core magnetic distortion, and the performance can be further improved.

In the case where the shape of the tip of the core positioning pin is substantially spherical or substantially conical, the pin hole can be made smaller to improve the waterproof insulation performance.

Also, in the case where the recessed step is provided in the core contact portion of the bobbin flange, the resin can be reliably filled, and the insulation sealing performance between the coil and the core is improved and stabilized. It is.

In the case where the coil lead wire is wired along the inner wall of the groove and along the surface of the bobbin flange portion, it contributes to prevention of disconnection during molding or a heat cycle test.

Further, in the case where a large number of satin-like convex portions are provided in the molded portion on the side surface of the terminal pin planting block of the bobbin flange, it is possible to improve the mold release workability when the mold is opened. It is.

In the case of a thermoplastic resin used for molding, which has a low crystallization rate and substantially the same linear expansion coefficient and heat shrinkage as the thermoplastic resin, it is difficult to use a heat-resistant resin such as a heat cycle test. The resin crack resistance against impact is improved.

As described above, the present invention provides high efficiency, high performance,
The present invention can provide a mold transformer having extremely high industrial value by using a thermoplastic resin mold such as high reliability and high productivity.

[Brief description of the drawings]

FIG. 1 is a sectional view of a molding die which is a main part of an embodiment of a method for manufacturing a mold transformer of the present invention.

FIG. 2 is an exploded perspective view of a transformer main body, which is a main part of the transformer.

FIG. 3 is a perspective view of a transformer main body, which is a main part of the transformer.

FIG. 4 is a perspective view of the molded transformer as viewed from a pin terminal side.

FIG. 5 is a perspective view of the mold transformer as viewed from above.

FIG. 6 is a cross-sectional view of a development example of a core positioning pin as the main part.

FIG. 7 is a sectional side view of the same.

FIG. 8 is a top sectional view of the same.

FIG. 9 is a sectional side view of the same.

FIG. 10 is a top view of a transformer main body which is a main part of the transformer.

FIG. 11 is a cross-sectional view of the mold transformer and a mold.

FIG. 12 is a perspective view of the mold transformer.

FIG. 13 is an exploded perspective view of a transformer main body, which is a main part of a conventional mold transformer.

FIG. 14 is a perspective view of a transformer main body, which is the main part.

FIG. 15 is a sectional view of a mold of the mold transformer.

FIG. 16 is a perspective view of the same.

FIG. 17 is a sectional side view of the same.

FIG. 18 is a top sectional view of the same.

FIG. 19 is a sectional side view of the same.

FIG. 20 is a top view of a transformer main body, which is a main part of the transformer.

FIG. 21 is a sectional view of a mold of the mold transformer.

[Explanation of symbols]

 Reference Signs List 4 coil 5 lead wire 6 terminal 8 E-type laminated core 10 I-type laminated core 11 butt joint 16 mold resin 18 E-type laminated core middle foot 22, 23 flange 24 bobbin 25 groove 26 center hole 27 transformer body 28 mold metal Mold 28a Movable mold die 28b Fixed mold die 29 Fixed core positioning pin 30 Gate 31 Mold transformer 32 Core outer circumference 33 Coil outer circumference 34 Spring embedded core positioning pin 35 Substantially spherical core positioning pin 36 Substantially conical core Positioning pins 37, 38 Recessed step 39 Outer peripheral surface of bobbin terminal pin planting block 40 Convex part 41 Mold transformer 42 Ejector pin 43 Recess 44 Inner wall surface 45 Side wall C, D, E Clearance

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H01F 27/32 H01F 41/12

Claims (7)

(57) [Claims] A bobbin forming step of forming a center hole, forming flanges at both ends, implanting a plurality of terminal pins at a lower end of the flange, and forming a groove in a flange portion between the terminal pins; A coil winding step in which a coil is wound around the bobbin, a lead wire wiring step in which a lead wire of the coil is wired to the terminal pin, and inserting a sun-shaped laminated core into a center hole of the bobbin. a transformer body forming step of forming a trans body holds the transformer body in the mold die includes a molding step of injecting a molding resin made of thermoplastic resin into the mold, the molding process Is the transformer body
In the side of the mold, under the laminate core
Gate for injecting the mold resin opened toward
And providing the molding resin from the gate to the molding
A method of manufacturing a mold transformer that is injected into a mold and molded. 2. A mold for a fixed mold and a mold for a movable mold.
The fixed side mold has a
Multiple spring-type core positioning to position the core
A pin is provided, and the movable mold is
Set a fixed positioning pin to position the minate core.
The fixed core positioning pin is
2. The device according to claim 1, wherein six or more locations are provided at substantially equal intervals on the upper surface of the device.
Method of manufacturing a mold transformer. 3. A spring-embedded core positioning pin and a fixed
Each of the core positioning pins has a substantially spherical tip.
3. The mold transformer according to claim 2, wherein the mold transformer has a substantially conical shape.
Manufacturing method. 4. The bobbin forming step includes the steps of :
Laminate the laminated core on the face of the bobbin flange facing
Length and the laminate core product
A concave portion is formed in the layer direction, and in the molding process, the concave portion is formed.
Mold resin is injected between the
2. The method of manufacturing a mold transformer according to claim 1, wherein the mold transformer is molded in a mold.
Method. 5. The lead line wiring step includes forming a lead line in a groove.
Creepage the pull Te along Align turn the wiring to the terminal pins of the inner wall and the flange
The method for manufacturing a mold transformer according to claim 1. 6. An end of a bobbin in a molding step.
The inner surface of the fixed mold that faces the periphery of the collar where the child pin is planted
On the bobbin terminal pin.
On the surface of the mold resin around the outer periphery of the collar
2. The production of the mold transformer according to claim 1, wherein the projection is formed.
Construction method. 7. The crystallization speed is reduced by lowering the crystallization start temperature and increasing the recrystallization temperature, and
2. The method for manufacturing a mold transformer according to claim 1, wherein the molded transformer is molded with a thermoplastic resin having a performance in which a linear expansion coefficient and a temperature shrinkage coefficient of the resin are made substantially equal.