JPH0682772B2 - Lead forming method for surface mount device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for cutting and bending a lead of a surface mounting device mounted on a printed wiring board or the like.

[Conventional technology]

Conventionally, the method of cutting the projecting leads by the outer shell made of a hexahedral insulator of this surface-mounted device (hereinafter referred to as a device) to a required length and bending it has been performed by pressing except for hand processing. .

FIGS. 4 (a) and 4 (b) are partial cross-sectional views of a mold for explaining an example of a conventional method for molding leads of a device. First, as shown in FIG. 4A, the outer shell 1 of the device is inserted into the recesses of the upper mold 5 and the lower mold 4, and the leads 2 are held between the upper mold 5 and the lower mold 4. Next, the cutting punch 3 is lowered to cut the lead 2 into a required length.

Next, as shown in FIG. 4 (b), the bending die is opened, and the outer shell 1 of the device is put into the recess between the upper die 8 and the molding die 7. Next, the upper die 8 is lowered to the pad 6 of the upper die 8.
The lead 2 is sandwiched and fixed by the and the protrusion 10 of the molding die 7. Next, the molding punch 9 is lowered, and the leads are bent at the molding surface inside the molding punch 9 and the molding surface outside the projection 10. At the same time, the flat portion of the tip of the molding punch 9 and the flat portion of the molding die 7 sandwich the tip portion of the lead 2 and are bent back.

The surface of the tip of the lead that is bent back is generally parallel to the surface of the outer shell 1 that faces the printed wiring board.

[Problems to be Solved by the Invention]

FIG. 5 is a cross-sectional view of a part of the bending die and a part of the device showing a state where the leads of the device are molded, and FIG. 6 is a perspective view of the device where the leads are molded. Usually, the leads of the device are plated with solder in order to improve the wettability of the solder on the surface thereof. Therefore, when the leads of the device are molded by the above-described conventional method, at the time of molding, the leads and the molding surface inside the molding punch or the molding surface of the protrusion 10 of the molding die rub, and as shown in FIG. The solder plating may peel off and the solder scrap 11 may adhere to the mold.

It is said that the attached solder scrap 11 becomes larger as the number of forming times increases, and finally, the solder scrap 11 adheres to the lead 2 so as to short-circuit with the lead 2 of the device, as shown in FIG. There are drawbacks. Further, during this lead molding, there is a drawback that resin burrs and foreign substances that have fallen onto the molding die 7 adhere to the solder surface of the lead 2 and deteriorate the solder wettability.

An object of the present invention is to provide a lead forming method for a device in which a solder scrap is generated during the lead forming of the device and adheres to the lead, and a resin flash or foreign matter does not adhere to the lead.

[Means for Solving the Problems]

A lead forming method for a surface mount device according to the present invention includes a step of cutting a lead projecting from a side surface of an outer body of a hexahedron made of an insulator into a predetermined length, and a lead near the outer body of the cut lead. A lead bending step of pressing a portion with a molding punch and bending it in one direction, and pressing the tip of the lead against a flat surface of a molding die by the molding punch and bending back the tip in parallel to a surface orthogonal to the side surface of the outer shell. In a lead forming method for a surface-mounting device, which includes a tip-turning step of forming a portion, the lead bending step is a method in which a forming punch always bends a lead while vertically pushing the lead, and the tip-turning step is the forming step. A method in which the tip of the lead is pressed against the curved surface of the moldable roller by a punch and the tip of the lead is bent back. Configured to include it is.

EXAMPLES Next, the present invention will be described with reference to the drawings.

FIGS. 1 (a) and 1 (b) are sectional views of the mold shown in the order of steps for explaining one embodiment of the present invention, and FIG. 2 is a partially enlarged view of the mold of FIG. 1 (a). is there. The lead forming method for this device is the same as the conventional method for cutting the leads.

In the lead forming method which is the subsequent step, first, the device cut into the leads of a predetermined length is processed into the upper die 8a and the forming die 7a.
Insert it into the dent. Next, the lead 2 is sandwiched and fixed by the pad 6a of the upper die 8a and the protrusion 10a of the molding die 7a. Next, the molding punch 9a descends and hits the lead 2, and at the same time, the cam roller 13 attached to the rear end of the molding punch 9a follows the outer shape of the protrusion of the upper die, and the molding punch 9a is centered on the fulcrum 10. Since 9a can rotate, its tip descends in the direction of arrow 17, drawing an arc.

This lead molding pattern will be described with reference to FIG. 2. First, as the molding punch 9a descends, the molding punch 9a
First, the lead 2 is struck at a position indicated by A, and the lead is bent. Next, when the forming punch 9a descends while drawing a circular arc as shown by the arrow 17, the lead 2 is bent until its tip contacts the point D of the forming roller 15.

Next, the forming punch 9a further descends, and the lead 2 starts to be folded back from the point B. On the other hand, since the forming roller can freely rotate, the forming roller 15 rotates from the contact point D with the tip of the lead 2 in the direction of the arrow 21 without stumbling with the lead 2. Next, when the forming punch 9a reaches the lowest point C, the bending of the lead 2 is completed and the contact point between the lead 2 and the forming roller 15 is D by the rotation of the forming roller 15.
To E.

In this way, when bending the lead 2, the forming punch
The forming punch 9a descends in the direction of arrow 17 so as to draw a circular arc connecting A, B, and C around the bending center 18 of the lead 2 so that the direction in which the 9a abuts the lead 2 surface is always vertical. In addition, by forming a freely rotating forming roller on the side of the forming die 7a so that no stumbling occurs between the forming roller 15 and the lead 2 that comes into contact with the forming roller 15, the lead 2 and the lead are not formed at the time of forming. No longer scraping the plating by rubbing between.

Further, between the molding die 7a and the molding roller 15, for example, 0.
If a gap of about 2 to 0.5 mm is provided, the resin burr and foreign matter 19 separated during lead molding pass through this gap and are discharged out of the mold as the molding roller 15 rotates.

Here, when the leads of the device are not molded to a predetermined size, if necessary, as shown in FIG. 1 (b), the device in which the leads are bent is inserted into the recess of the mold and The mold 8 is lowered, the lead 2 is sandwiched and fixed, and the molding punch 9 is lowered to correct and mold the lead 2 to have a predetermined size.

FIG. 3 is a sectional view of a mold showing another embodiment of the present invention. In addition to the mold used in the above embodiment, the third
Similarly, the die shown in the figure can be used to mold leads.

That is, in this mold, instead of the above-mentioned cam roller, the plate cam 20 is provided on the side surface of the forming punch 9b, and the side surface of the forming punch 9b is formed to have a contour corresponding to the plate cam 20. As a result, forming punch 9b is indicated by arrow 17
In the same manner as in the above-mentioned embodiment, the lead is molded by lowering it in the direction indicated by (1) so as to draw an arc around the bending center point of the lead. Other than that, it is the same as the above-mentioned embodiment.

〔The invention's effect〕

As described above, the present invention, when bending the lead, moves so as to draw an arc around the bending point of the lead as the forming punch descends so that the tip of the forming punch always hits vertically, and further, Since the lead is formed by providing a self-rotating forming roller that bends back the tip of the lead, no sneak occurs between the lead and the mold.
The fact that the shaving does not occur means that the solder plating of the leads is not peeled off, and the generated resin burrs and debris are discharged out of the mold by the rotation of the molding roller.

Therefore, there is an effect that a device lead forming method can be obtained in which solder scraps are generated during device lead forming and adhere to the leads, and resin burrs and foreign substances do not adhere to the leads.

[Brief description of drawings]

1 (a) and 1 (b) are cross-sectional views of the mold shown in the order of steps for explaining one embodiment of the present invention, and FIG. 2 is a partially enlarged view of the mold of FIG. 1 (a). FIG. 3 is a cross-sectional view of a mold showing another embodiment of the present invention, and FIGS. 4 (a) and 4 (b) are partial cross-sectional views of the mold for explaining an example of a conventional method for forming leads of a device. 5 and FIG. 5 are cross-sectional views of a part of the bending mold and a part of the device in which the leads of the device are molded, and FIG. 6 is a perspective view of the device with the leads molded. 1 ... Outer body, 2 ... Lead, 3 ... Cutting punch, 4 ...
… Lower mold, 5 …… Upper mold, 6,6a …… Pad, 7,7a …… Molding die, 8,8a, 8b …… Upper mold, 9,9a, 9b …… Molding punch, 10,10a …… Protrusion, 11 …… Solder scrap, 12 …… Protrusion, 13 …… Cam roller, 14 …… Support point, 15 …… Forming roller, 16,17,21 …… Arrow, 18 …… Bending center, 19 ……
Foreign matter, 20 ... plate cam.

Claims (1)

[Claims] 1. A step of cutting a lead projecting from a side surface of an outer shell of a hexahedron made of an insulator into a predetermined length, and pressing a lead portion near the outer shell of the cut lead with a molding punch. A bending step of bending the lead in a direction, and pressing the tip of the lead against the flat surface of the molding die by the molding punch to fold it back and fold the tip to form the tip in parallel to the surface orthogonal to the side surface of the outer shell. In a lead forming method of a surface mount device, the lead bending step is a method in which a forming punch always bends a lead while vertically pushing the lead, and the tip folding step includes a tip portion of the lead by the forming punch. Surface mounting characterized by a method in which the tip end portion of the lead is bent back by pressing on the curved surface of a molding roller capable of rotating. Lead molding method of vice.