JP2002043135A - Ferrite bobbin and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vertical axis type ferrite bobbin having a very low height and a method of manufacturing the bobbin. SOLUTION: The ferrite bobbin is formed by performing fluting and cutting on a columnar base ferrite material, while the material is being rotated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultra-thin ferrite bobbin for a surface-mount type coil component used for a transformer, a choke coil and the like, and a method for manufacturing the same.

[0002]

2. Description of the Related Art Ferrite cores are used in transformers and choke coils of power supplies of various electronic devices.

In recent years, as electronic devices such as portable information terminals have become lighter and thinner, there has been a strict requirement to keep the mounting height of the core low.

For example, a typical structure of a surface mount type coil component is to wind a resin coil bobbin provided with a frame lead terminal on a side surface or a bottom surface, and wrap both ends of the coil bobbin around the frame lead terminal. It has a structure in which the magnetic core is fitted into the coil bobbin by soldering or the like, and the use of a resin coil bobbin limits the height reduction, and the minimum height is about 3 mm.

Therefore, as a structure with a reduced height, FIG.
As shown in the vertical sectional view of FIG. 1, a ferrite bobbin 10 including a winding body 105 and integral flanges 103 provided at both ends of the winding body 105 by omitting a resin coil bobbin.
1 is wound directly with an insulated conductor to form a winding 102;
A surface-mounted coil component 100 having a structure in which a metal plate having the winding end portion planted on one flange 103 is wrapped around a press-formed thin plate-shaped lead terminal 104 and soldered is commercialized.

[0006] As shown in a longitudinal sectional view of FIG.
Instead of the lead terminal 104, an electrode layer 111, which is formed by directly printing a conductive paste or the like on the bottom surface or the peripheral surface of one of the flanges 103 of the drum-type ferrite bobbin 101 on the vertical axis or both, is provided. There is a surface-mount type coil component 110 having a structure in which an end of 102 is conductively fixed to the electrode layer 111.

At present, the surface mount type coil component 110 using the vertical type drum type ferrite bobbin 101 having a height H = 1.2 mm as shown in FIG. It is of height dimensions.

The above-mentioned drum type ferrite bobbin 101 is grooved by a method as shown in the conceptual view of FIG.
This equipment is hereinafter referred to as a continuous drum grooving machine.

[0009] The ferrite base material 121 having a substantially cylindrical shape is grooved by a diamond wheel 123 rotating at a high speed while rotating on the peripheral surface of the controller 122 to form a bobbin-shaped ferrite bobbin 101.

As shown in FIG. 13, the method of supplying the ferrite base material 121 and the method of taking out the ferrite bobbin 101 after the processing are as follows. The ferrite base material 121 is fed in the rolling direction by a parts feeder (not shown) or the like.
31 and the work holder 133 of the carrier 132
Are supplied one by one. By slowly rotating the carrier 132, the carrier 132 is passed through the gap with the diamond foil 123, and grooving is performed one by one successively.

When the grooving is performed, the ferrite base material 121 is rotating at the same peripheral speed as the controller 122. The ferrite bobbin 101 after the grooving process is discharged onto the discharge rail 134.

Further, as shown in a cross section in FIG. 14, the ferrite base material 121 is positioned on the positioning plate 141 side. Therefore, the thickness T2 of the portion of the carrier 132 that contacts the ferrite base material 121 needs to be smaller than the flange thickness T3 after grooving. If the thickness T2 is equal to or greater than the flange thickness T3, it comes into contact with the diamond foil 123,
3 or the carrier 132 is lost.

As described above, the flange thickness T3 and the carrier 132
In order to support the load at the time of grooving in the portion of thickness T2, there is naturally a limit in reducing the thickness thereof. Therefore, in ferrite bobbin 101, overall thickness H = 1.2 m
m, the flange thickness T3 is 0.4 mm, and the groove width is about 0.4 mm is the minimum height.

Further, as shown in FIG. 6 using the above-described continuous drum grooving machine, the flange has a cutout 61 for leading a winding to a part of the outer periphery thereof. In order to manufacture the bobbin 60 provided with the straight portion 62 to improve the convenience, the body section 63 of the winding body does not become a perfect circle. This is because the reference at the time of the grooving processing is the outer diameter of the drum part, so when the notch 61 or the linear part 62 comes on the controller 122, it goes away from the diamond wheel 123, and the core diameter φD1 of the part becomes the normal part φd1. It is because it becomes larger.

As described above, in order to form the bobbin shape in the continuous drum grooving machine, the outer shape must be a circle or a substantially circular shape in order to roll the side surface of the controller 122.

Further, as shown in a conceptual view in FIG. 15, there is a method of forming a groove by approaching a diamond wheel 123 which rotates at a high speed by sandwiching the ferrite base material 121 having a substantially cylindrical shape from above and below by a rotating support 151. In this method, each ferrite base material 121 is grooved while being sandwiched and rotated, and is placed at a predetermined location. Hereinafter, this is referred to as a single drum grooving machine.

[0017]

In recent years, electronic devices have become lighter, thinner and smaller, but on the other hand, the amount of information to be communicated has increased dramatically, and the capacity required for transformers and choke coils has also increased. ing. Accordingly, in order to secure the capacity, the outer diameter of the ferrite bobbin is required to be 3 mm or more, and further, the height is required to be 1 mm or less in order to realize a light and thin device.

As described above, in the continuous drum grooving machine, a rotating force is given by the flange portion of the ferrite bobbin, and the height of the grooving machine has reached the limit of reducing the height to support the load during grooving. I could not do the following.

In the case where the core has a notch 61 or a straight line 62 in a part of the outer periphery, the winding speed in the winding step is lower than the bobbin because the cross-sectional shape of the core is not a perfect circle due to its processing principle. , The variation easily occurs. Therefore, there is also a disadvantage that the performance of the coil product varies. In addition, since a rectangular outer shape does not roll, it cannot be manufactured.

Further, in the method of individually processing shown in FIG. 15, the ferrite base material 121 is positioned, pinched, rotated, grooved while rotating, and placed in a predetermined place. It is not suitable as a method for producing a core of a coil component, which takes a long time, increases mass production cost, and becomes cheaper year by year.

Further, in the above two methods, secondary processing is required to provide the winding lead-out groove 71 inside the flange 3 of the ferrite bobbin 90 shown in FIG. Costly to have.

Furthermore, the surface roughness of the inner side 124 of the flange becomes Ra65 or more due to the grooving process using the diamond foil 123, and the insulating coating of the winding, which has been reduced in size every year and the winding diameter has been reduced, is damaged. Defective coil components occur.

Further, since the boundary between the winding drum portion and the flange is edge-shaped due to the grooving process using the diamond wheel 123, stress concentration is apt to occur and the strength is reduced.

The present invention has been made in view of the above circumstances, and is intended to reduce the height of a ferrite bobbin used for a vertical-axis type surface mount type coil component while having low-cost mass productivity. .

[0025]

SUMMARY OF THE INVENTION The present invention relates to a ferrite bobbin comprising a winding body for winding a winding wire and integral flanges provided at both ends of the winding body, and a cross section of the winding body. The shape is substantially circular, the outer diameter of the flange is 5 mm or more, and the overall height is 1/5 or less of the outer diameter of the flange.

Further, the boundary between the winding drum section and the flange is curved, and a groove is provided on the inner surface of the flange.

Further, the present invention provides a method for manufacturing a ferrite bobbin, comprising the steps of forming a plurality of grooves with a multi-wire saw while rotating a columnar base material made of ferrite, and thereafter cutting between the grooves with the multi-wire saw. Features.

Further, in the above manufacturing method, the groove is formed by using a multi-wire saw having an outer diameter equal to the width of the groove.

Further, the method is characterized in that after forming the above-mentioned groove, cutting is performed using a multi-wire saw smaller than the groove width.

Further, a groove is formed by using a multi-wire saw narrower than the width of the groove, and a desired groove width is obtained by shifting the multi-wire saw or the columnar base material in the axial direction in that state.

Further, after forming the groove with the multi-wire saw, the rotation of the columnar base material is stopped, and the groove is formed on the inner surface of the flange by shifting the multi-wire saw or the columnar base material in the axial direction. .

[0032]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows an example of the ferrite bobbin of the present invention. A pair of flanges 3 are provided at both ends of a winding body 2 for winding a winding.

In the case of the round ferrite bobbin 1 shown in FIG. 1A, if the outer diameter is φD and the height is H, then H ≦ φD / 5.

Similarly, if the diagonal distance of the outer side of the polygonal ferrite bobbin 1 in FIG.
D / 5.

That is, the ferrite bobbin 1 of the present invention is provided with a polygonal flange 3 having an outer diameter of 5 mm or more or a diagonal distance of 5 mm or more at both ends of a substantially circular body 2, and the height H is D / 5 or less. FIG. 1
In (b), the shape is a square, but it may be a polygon having five or more angles.

FIGS. 2A and 2B are a schematic view and a front view, respectively, showing a multi-wire saw for producing the ferrite bobbin 1 of the present invention.

As shown schematically in FIG. 2 (A), the multi-wire saw of the present invention comprises a cutting unit 11 for grooving and cutting a columnar base material 10 and a cutting unit X-
Work feed unit 1 whose position can be continuously adjusted in the Z direction
It consists of two.

FIG. 2B shows a multi-wire saw body 200.
As shown in FIG.
The spindle units 202A, 202B and 202C are arranged so as to form a triangle. Spindle unit 202A,
Rollers 203A, 203B, and 203C each having a spiral groove formed on the outer periphery are rotatably supported by B and C, respectively.
Then, the saw wire 204 is attached to the rollers 203A to 203C.
Are successively wound to form a wire row 205. The saw wire 204 is sequentially wound around guide rollers 206A, B, C, and D rotatably supported by a frame (not shown) and guided to the other end. At the other end, both ends are joined together by laser welding or the like to form an endless shape.

Further, a tension roller 207 for applying a predetermined tension to the traveling saw wire 204 is provided. The tension roller 207 is connected to the guide roller 2.
A tension weight 208 having a predetermined load is hung from the outside, and is vertically movably supported.

The output shaft of a roller rotation motor 209 is connected to the uppermost roller 203A among the three rollers 203A to 203C. The wire row 205 stretched as described above travels by rotating the roller 203A with the roller rotation motor 209.

Next, the structure of the work feed unit 12 will be described. A pair of guide rails 220 are laid on the frame 201, and the work feed unit 12 is slidably supported on the guide rails 220.

The screw rod 2 is arranged in parallel with the guide rail 220.
The output shaft of a vertical feed motor 222 provided at the lower part of the frame 201 is connected to the lower end of the screw rod 221. By driving the vertical feed motor 222, The screw rod 221 rotates.

A nut member (not shown) combined with the screw rod 221 is fixed to the work feed unit 12. Therefore, the work feed unit 12
Drives the screw 221 by driving the vertical feed motor 222.
Is rotated up and down along the guide rail 220.

The work feeding unit 12 includes a columnar base material 10, a work rotation motor 223 for rotating the columnar base material 10 to which an output shaft is connected, a work table 224 on which these are installed, and a work table 224. A table guide 226 for moving the wire array 205 in a direction perpendicular to the wire row 205, and a table moving motor 2 for driving the table guide 226.
25 and the unit plate 227 on which they are installed
It consists of.

The method of moving the work table 224 is performed in the same manner as the above-described method using the screw rod and the nut member.

Although each unit is moved by a method using a motor, a screw rod, and a nut member here, other methods such as a cylinder or a belt using a fluid may be used as the moving means.

Here, a method for manufacturing the ferrite bobbin 1 of the present invention will be described.

As shown in FIG. 3, the columnar base material 10 is grooved with a multi-wire saw 200 to form a groove 31, and then the work table 224 is shifted by a pitch dimension L1 and then cut by the multi-wire saw 200 again. By processing, a large number of ferrite bobbins 1 can be simultaneously formed.

In this figure, the columnar preform 1
0, the groove 31 is formed, then the rotation of the columnar base material 10 is stopped and fixed, and cutting is performed by the multi-wire saw 200. However, in order to reduce the change in cutting resistance to the saw wire 204, the columnar base material is reduced. Cutting may be performed while the material 10 is being rotated.

As described above, in order to apply a rotational force from the end of the columnar base material 10, the flange 3 does not bear the rotational force or the load of the grooving process. Therefore, the thickness of the flange 3 can be reduced as compared with the related art.

It is difficult to shorten the length of the winding drum 2 because it directly relates to the electrical characteristics of the finished product. Therefore, in order to keep the overall height of the ferrite bobbin low,
It is very useful to reduce the thickness of the film.

According to the manufacturing method of the present invention, for example, the outer diameter of the flange 3 is 5 mm or more, the height of the winding drum 2 is 0.5 mm, and the thickness of the flange 3 is 0.25 mm. Certain products having an overall height H of 1 mm or less can be manufactured.

Since the saw wire 204 has an outer diameter substantially equal to the width of the groove 31, the cross section of the body 3 to be formed has a semicircular arc shape 32.
Therefore, since the connecting portion between the trunk portion 2 and the flange 3 is curved,
There is no concentration of stress, and the strength after completion of the ferrite bobbin 1 is increased.

Further, the surface roughness of the inner side surface 33 of the flange is 0.45 or less due to the grooving process using the saw wire 204 without using a diamond foil. Therefore, it is possible to prevent the insulating film of the winding, which has been reduced in size year by year and has a smaller winding diameter, from being damaged.

Next, another manufacturing method will be described. As shown in FIG. 4, after the groove 31 is grooved with the saw wire 204 having an outer diameter substantially equal to the groove width, the groove 31 is cut into a saw wire 204A that is thinner than the saw wire 204.
1 is less, and more ferrite bobbins 1 can be produced from the columnar base material 10.

Further, as shown in FIG. 5, the work table 224 is grooved with a saw wire 204A smaller than the width dimension of the groove 31, and the work table 224 is moved a desired distance L2 in this state, thereby obtaining a desired groove width. And Then, the table vertical feed motor 222 is rotated in the reverse direction,
04A is pulled out of the columnar base material 10, the work table 224 is moved by a distance L3, and the columnar base material 10 is cut to form the ferrite bobbin 1.

Therefore, according to this manufacturing method, the R shape dimension 51
Can be reduced, and many windings can be easily aligned at the connecting portion between the winding drum section 2 and the flange 3, and it is possible to suppress variations in electrical characteristics of a finished product. for that purpose,
R shape dimension 5 smaller than the radius of the winding wound on the winding drum 2
It is desirably set to 1.

Further, since the cutting is performed with the thin saw wire 204A, the cutting margin 41 is also reduced, and more ferrite bobbins 1 can be produced from the columnar base material 10.

According to the production method of the present invention, as shown in FIG.
Notch 6 for leading the winding to part of the outer periphery of the flange
No. 1 or the bobbin 60 provided with the linear portion 62 for improving the convenience in automatic mounting, the cross-section of the winding drum portion is a perfect circle even when grooving by any of the multi-wire saw methods described above. become. Therefore, since the winding speed in the winding step does not change during one round of the bobbin 60, variations can be suppressed. Therefore, the variation in the performance of the coil product can be reduced.

In the case of the bobbin 60 or a rectangular outer shape, the outer shape is not circular at the very initial stage when grooving or cutting is performed.
And the contact of the columnar base material 10 is intermittent. Therefore, since the processing load changes, the processing accuracy tends to vary. Therefore, in the very initial stage of processing, the speed of the work rotating motor 223 is reduced to suppress the occurrence of variation,
If it is programmed to return the speed of the work rotating motor 223 at the stage where the wire row 205 always comes into contact with the columnar base material 10, it is possible to produce a product of stable quality without impairing mass productivity. .

FIG. 7 is a sectional view, and FIG. 8 is a perspective view of each ferrite bobbin 1 after cutting.
When the rotation of the work rotation motor 223 is stopped and the table moving motor 225 is operated by a desired amount after the machining is completed, the guide groove 71 for guiding the end of the winding start side to the inside of the flange 3 by the saw wire 204A. Can be formed.

Therefore, as shown in FIG. 9, when the winding start side end of the winding is led out from the collar 3 using the lead-out groove 71, the winding can be regularly aligned over the entire circumference. Winding variations can be suppressed. Therefore, the variation in the performance of the coil product can be reduced.

The ferrite constituting the ferrite bobbin 1 of the present invention includes a Mn—Zn ferrite containing Fe ₂ O ₃ —MnO ₂ —ZnO as a main component, and a Fe ₂ O ₃ —NiO—Zn.
Ni-Zn ferrite containing O as a main component is used.
In each case, in addition to the above main components, SiO ₂ , CuO, Bi ₂
One or more of O ₃ and CoO can be added, and ferrite having an initial magnetic permeability of 1 to 2000 is used.

The columnar base material 10 is formed by adding a known auxiliary to the raw material powder of ferrite and extruding the same.
The obtained molded body can be obtained by firing at 950 to 1350 ° C.

[0066]

EXAMPLES Table 1 shows a comparison table of ferrite bobbins prepared according to the present invention and conventional specifications.

The production method using the multi-wire saw of the present invention can be manufactured with high productivity in all items. Of course, a product of the conventional size can be manufactured, and it is possible to cope with production of other products.

The outer shape is φ5 mm and the overall thickness is １ ／ of the outer shape.
When a core of 1 mm is manufactured, it cannot be manufactured by a continuous drum grooving machine, and mass productivity cannot be secured by a single drum grooving machine.

Similarly, a core having a square shape, a notch or a straight portion, and a body portion having a perfect circular shape cannot be manufactured by a continuous drum grooving machine, and mass production by a single drum grooving machine can be ensured. Did not.

Further, a device having a winding lead-out groove inside the flange cannot be manufactured by a continuous drum grooving machine or a single drum grooving machine.

Further, the surface roughness of the inner surface of the flange is Ra 0.65 for a continuous drum grooving machine using a diamond foil and a single drum grooving machine, and Ra 0.45 for a production system using a multi-wire saw. Met.

[0072]

[Table 1]

[0073]

As described above, according to the present invention,
Conventionally, it was impossible by manufacturing a ferrite bobbin from a process of forming a plurality of grooves with a multi-wire saw while rotating a columnar base material made of ferrite and then cutting between the grooves with a multi-wire saw. In addition, a low-profile longitudinal ferrite bobbin can be manufactured at low cost.

In a ferrite bobbin comprising a winding drum for winding a winding by the above manufacturing method and integral flanges provided at both ends of the winding drum, the cross section of the winding drum is substantially circular. A ferrite bobbin characterized in that the outer diameter of the flange is 5 mm or more and the overall height is 1/5 or less of the outer diameter of the flange can be obtained. I can do it.

[Brief description of the drawings]

FIGS. 1A and 1B are perspective views of a ferrite bobbin of the present invention.

FIG. 2A is a conceptual diagram of a multi-wire saw used in the manufacturing method of the present invention, and FIG. 2B is a front view of the same main body.

FIG. 3 is a cross-sectional view illustrating a method of manufacturing a ferrite bobbin according to the present invention.

FIG. 4 is a cross-sectional view illustrating a method of manufacturing a ferrite bobbin according to the present invention.

FIG. 5 is a cross-sectional view illustrating a method for manufacturing a ferrite bobbin of the present invention.

FIG. 6A is a perspective view of a ferrite bobbin having a notch or a straight portion in a flange, and FIG. 6B is a cross-sectional view.

FIG. 7 is a cross-sectional view showing an example of processing of the multi-wire saw of the present invention.

FIG. 8 is a perspective view of a ferrite bobbin having a lead-out groove for leading a winding inside a flange.

FIG. 9 is a perspective view of a coil component having a guide groove for guiding a winding inside a flange.

FIG. 10 is a cross-sectional view showing an example of a conventional surface mount type coil component.

FIG. 11 is a cross-sectional view showing an example of a conventional surface mount type coil component.

FIG. 12 is a perspective view showing the concept of a conventional continuous drum grooving machine.

FIG. 13 is a side view showing the concept of a conventional continuous drum grooving machine.

FIG. 14 is a sectional view showing the concept of a conventional continuous drum grooving machine.

FIG. 15 is a perspective view showing the concept of a conventional single-shot drum grooving machine.

[Explanation of symbols]

 1: Ferrite bobbin 2: Wound trunk 3: Flange 10: Columnar base material 11: Cutting unit 12: Work feed unit 200: Wire saw body 201: Frame 202A, B, C: Spindle unit 203A, B, C: Roller 204, 204A: saw wire 205: wire row 206A, B, C, D: guide roller 207: tension roller 208: tension weight 209: roller rotation motor 220: guide rail 221: screw rod 222: table vertical feed motor 223: work rotation motor 224: Work table 225: Table moving motor 226: Table guide 227: Unit plate 31: Groove 32: Semicircular shape 33: Inner side surface of flange 41: Cutting margin 51: R shape dimension 60: Bobbin 61: Notch portion 62 : Straight section 63 Body section 71: Outgoing groove 90: Ferrite bobbin 100: Surface mount type coil part 101: Ferrite bobbin 102: Winding 103: Flange 104: Lead terminal 105: Winding body part 110: Surface mount type coil part 111: Electrode layer 121 : Ferrite base material 122: Controller 123: Diamond foil 124: Inner side surface of flange 131: Rail 132: Carrier 133: Work holding part 134: Discharge rail 141: Positioning plate 142: Partial thickness T2 143: Flange thickness T3 151: Rotation support body

Claims (8)

[Claims] In a ferrite bobbin comprising a winding drum for winding a winding and integral flanges provided at both ends of the winding drum, the cross section of the winding drum is substantially circular. A ferrite bobbin, wherein the outer diameter of the flange is 5 mm or more, and the overall height is 1/5 or less of the outer diameter of the flange. 2. The ferrite bobbin according to claim 1, wherein the boundary between the winding drum section and the flange is curved. 3. The ferrite bobbin according to claim 1, wherein a groove is provided on an inner surface of the flange. 4. A method for producing a ferrite bobbin, comprising the steps of forming a plurality of grooves with a multi-wire saw while rotating a columnar base material made of ferrite, and thereafter cutting between the grooves with the multi-wire saw. 5. The method for manufacturing a ferrite bobbin according to claim 4, wherein the groove is formed using a multi-wire saw having an outer diameter equal to the width of the groove. 6. The method for producing a ferrite bobbin according to claim 5, wherein after forming the groove, cutting is performed using a multi-wire saw having a width smaller than the groove width. 7. A groove is formed using a multi-wire saw narrower than the width of the groove, and a desired groove width is obtained by shifting the multi-wire saw or the columnar base material in the axial direction in that state. 5. The method for producing a ferrite bobbin according to 4. 8. A groove is formed on the inner surface of a flange by forming a groove with a multi-wire saw, stopping rotation of the columnar base material, and shifting the multi-wire saw or the columnar base material in the axial direction. A method for producing a ferrite bobbin according to claim 4.