JPH0136280B2 - - Google Patents

Description

Detailed Description of the Invention The present invention is an automatic lead wire for a printed board that automatically trims the lead wires protruding from the back side of the printed board after mounting and soldering of components to a predetermined length. This invention relates to a cutting device.

Conventionally, there are two methods for cutting lead wires as described below.

FIG. 1 is a schematic diagram showing one of them.

As shown in the figure, a disc-shaped cutting blade (including a saw blade) N is fixed to the shaft of the motor M. First, the printed board P on which the component E has been mounted and soldered is fixed onto the rail R using a jig F. At this time, the lower surface U of the printed board P
The distance between the cutting blade N and the cutting blade N is adjusted to a required dimension by, for example, moving the cutting blade N and the motor M up and down.

Next, the cutting blade N is rotated at high speed, and the printed board P is gently moved toward the front (perpendicular to the plane of the paper) along the rail R to cut the lead wire L to a required length. Although the cutting edge N is often made of ultra-hard material, a disc-shaped polishing plate may also be used.

FIG. 2 is a schematic diagram showing another example.

In the figure, a printed board P on which a component E is not mounted is placed on a template T that has a hole at a position corresponding to the mounting position, and the component E is mounted in this state, and when the mounting is completed, The cutting blade N is moved in the direction of the arrow to cut the lead wire.

However, both of the above methods have the following problems. In other words, regarding the former, a) Since the cutting blade rotates at high speed, heat is generated due to friction when cutting the lead wire. This heat remelts the soldered portion, but at this time, the soldered portion is subjected to cutting stress and vibration of the cutting blade. Therefore, when the remelted solder cools and hardens, it becomes unstable, reducing the reliability of the solder joint. Generally, in order to ensure this reliability, a method of re-soldering is used.

(b) Warpage occurs as printed boards become larger. This situation is shown in FIG. 3, and as is clear from the figure, the disk-shaped cutting edge N cannot follow this warpage.
In other words, the dimensions from the lower surface U of the printed board cannot be made constant.

c) After soldering, the lead wires do not necessarily stick out straight. This state is shown in Fig. 4 and Fig. 5. When the lead wire L is bent in the same direction as the cutting direction of the cutting edge N as shown in Fig. 5, as shown in Fig. 5. , it is cut at the dotted line position I, thus forming a sharp tip LN.

On the other hand, regarding the latter, a) Template T is used, so many types of templates must be prepared except in mass-produced production formats.

(b) Since the soldering process is performed after mounting, the parts will fall off unless they are fixed in some way until the soldering is completed. For this purpose, a method is used in which a thin plastic film is used, which is placed over the printed board, then evacuated and heat-adhered to fix it.
In this method, flux seeps into the end face of this film during soldering, making post-soldering processing difficult.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a lead wire cutting device which is more reliable and can be automated by eliminating the disadvantages of the above methods.

The above object is, according to the present invention, an automatic lead for printed circuit boards for automatically trimming lead wires one by one to a predetermined length that can protrude from the back side of a printed circuit board on which components have been mounted and soldered. In the wire cutting device, a work table that accepts the back side of the printed board in a predetermined direction and moves in a predetermined direction by a predetermined distance, and a work table that is installed on the back side of the printed board and moves by a predetermined distance together with the work table. A sensor approaches the back surface of the printed circuit board each time the printed circuit board is being cut, measures the cut lead length of one of the lead wires, and stops at a predetermined position, and the sensor further moves horizontally by a predetermined distance from the stopped position. a control device for selectively positioning the head with respect to the work table; and a control device for selectively positioning the head with respect to the work table. This is achieved by providing

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 6 is a perspective view showing an embodiment of the invention.

In the figure, W is a work table, and the printed board P on which parts have been mounted and soldered is placed on the printed board fixing template T provided in the center of the work table W on the soldering surface (with the protruding lead wires). side) Fix with A facing up.

A lead wire cutting head H is provided above the printed board P of the template T, and this head H includes a cutting blade N made of nippers or scissors and a cutting blade N for determining the cutting lead length of the lead wire. A needle sensor S is provided.

Note that MC is a control device that controls the drive of the work table W and head H, the operation of the cutting blade N, etc.
KY, typewriter TY and central processing unit CPU
It consists of a microcomputer consisting of

Now, with reference to the drawings, the operations of the work table W and the lead wire cutting head H, the shape of the cutting blade N, the relationship between the lead wire and the cutting position, etc. will be explained.

FIG. 7 is an explanatory diagram for explaining the order in which the lead wires L are cut, and FIG. 8 is a diagram showing the lead wire cutting head H.
Fig. 9 is an arrangement diagram showing the shape of the cutting blade N and the positional relationship between the cutting blade N and the lead wire L. Fig. 10 is a diagram showing the arrangement of four printed boards together. It is an explanatory view showing the case of cutting.

In FIG. 7, the work table starts from the machine origin (not shown) and the printed board P
The starting position of the lead wire cutting position, e.g.
The ST moves to a predetermined position relative to the head H and stops. Next, for example, it moves one pitch at a time in the longitudinal direction of the figure, and when one row is completed, it moves one pitch at right angles to the longitudinal direction, and then moves one pitch at a time in the opposite direction to the above. In addition, the lead wire L
protrudes like a mesh (lattice), and the size of the mesh is about 2.5 mm or 2.54 mm.

Therefore, one pitch of the work table is also 2.5
mm or 2.54mm.

Further, in this invention, the cutting is performed in the column direction, but the cutting may be performed in the row direction.In short, the cutting may be performed by moving one pitch at a time in the direction perpendicular to the cutting blade.

In Fig. 8, the cutting edge N provided on the head H
The position where the work table W stopped is set as the start position _N1 , and the position where the work table W stopped is set as the start position _N2.
When the sensor S descends to this point, the sensor S comes into contact with the soldering surface of the printed circuit board P. When the head H further descends and reaches the set dimension position, the head H is stopped by a signal from the sensor S.

Next, the head H moves horizontally to position _N3 and cuts the lead L. When cutting is finished, the cutting blade and sensor rise to position N ₄ and return to starting position N ₁ . When the cutting blade and sensor return to the _N1 position, the work table W moves one pitch.

The above operation is performed for all pitches, and when all the pitches have been moved, the work table W returns to the origin again.

The cutting blade N consists of nippers or scissors, and has a shape as shown in FIG. 9 when viewed from above. Due to the size of the lead wire L, its width is narrow enough that it does not touch the adjacent lead wire L.
Furthermore, the length of the cutting blade is designed to be short enough not to cut two lead wires L at once. In addition, in the figure, the lead wire L shaded with diagonal lines indicates that it has already been cut. In addition, in Fig. 9, SP indicates the position of the sensor S, and the position of the sensor S is determined by considering its position on the head so that it is as close as possible to the lead wire to be cut. Placed. In other words, a through hole for conducting between the front and back sides of the printed board P may be provided at a 1/2 pitch position of the lead wires of the printed board P.
The sensor S is arranged so as to be offset from 1/2 pitch.

The reason why the head operates as shown in FIG. 8 is to take into account folding or bending of the lead wire. In other words, since the straight part of the lead wire is close to the root (soldering part), in order to insert the cutting blade into this part and cut it, it is best to make the movement shown in the figure. In addition, the shape of the cutting edge is such that it is not obstructed by bent or cut lead wires.
NA needs to be parallel to the printed board surface, while arm NB needs to be at an angle. Further, the blade portion NA may be inclined or deflected upward.

The operation shown in FIG. 10 will be explained.

_First , _data and commands _are sent _to the microcomputer _, which is a control device, regarding the working ranges _{of the} work table _L I will give you.

As a result, the template T on the work table starts from the machine origin and moves to the first cutting point _K1 . In interval X ₁ , template T
moves one pitch at a time in the +X direction, skips section _X2 and moves to point _K2 . In section X ₃ ,
Similarly, move one pitch at a time, and when you reach point _K3 , move one pitch in the +Y direction (see point _K4 ).

Thereafter, similar operations are performed, and when the lead wires of printed boards _P1 and _P2 are completely cut at point _K5 or _K6 , section _Y2 is skipped and the process moves to point _K7 or _K8 .

Similarly, after cutting the lead wires of printed boards P ₃ and P ₄ , return to the machine origin from point K ₉ or K ₁₀ and stop.

This is the case where all the lead wires at all intersections on the printed board P are cut, and therefore,
In this case, there is no need to input data regarding the coordinates of each point to the microcomputer.

On the other hand, when performing selective cutting, such as when cutting except for the lead wires of an IC (integrated circuit), it is necessary to input data to that effect, but the position of the IC is usually are arranged regularly according to the design standard, so using this fact,
It is not data about each lead wire point by point, but
Data on one specific lead wire position of the IC,
All you have to do is input the number of lead wires.

As described above, according to the present invention, a work table, a head equipped with a sensor and a cutting blade, and a microcomputer that drives the work table and the head are provided, and one lead wire is connected under the control of the microcomputer. Because the lead wires are cut one by one, no heat is generated, so soldering only needs to be done once.Also, since the lead wires are cut one by one, there are no cutting errors, and the printed circuit board is No matter how crooked it is,
Since the cutting length is determined for each piece by a sensor, it has the advantage that cutting can be performed with high precision.

In addition, since a microcomputer is used as the control device, it is possible to automate the cutting operation, and also to freely select the cutting length of the lead wire, the operating range of the work table, and the selection of the lead wire to be cut. In addition, not only can the data processed by the lead wire cutting device of the present invention be easily stored, and the processing and processing based on the stored data can be easily performed, but inputs, outputs, and data corrections can be freely performed, and If this microcomputer is connected to other computers via a signal line, data can be exchanged and it can also function as a production control terminal.

Note that instead of the contact type sensor shown in FIG. 8, the sensor may be a non-contact type sensor that is advantageous against vibrations and the like.

Further, in this invention, the head is installed above the work table, but it is also possible to install the head inside the work table and set the printed board with the lead wires facing down.
This has the advantage that cut pieces of the lead wires do not fall onto the printed board.

Note that cutting debris can be easily removed by attaching a vacuum hose to the head.

Furthermore, by using a template for fixing the printed board, the cutting start position is automatically determined just by setting, so manual operations such as adjusting the star position are no longer necessary.

The head sensor can also be applied to automatic detection of the cutting area. In other words, if the work table moves and the sense position is removed from the printed board, a signal can be emitted so that detection can be easily made.

Applications of this invention include the following.

(b) By attaching a soldering iron to the head,
Used as an automatic soldering device.

In other words, on printed circuit boards, there are many parts that cannot be soldered due to dips, such as connector switches and IC sockets, and these soldering is mainly done manually, but it is possible to fully automate these operations. It can be done.

(b) By attaching a vacuum chuck to the head, a flat pack type automatic mounting machine for mini-sized electronic components can be realized.

(c) By attaching a punch to the head, scribing on sheet metal can be automated.

[Brief explanation of drawings]

Figures 1 and 2 are side views showing the conventional lead wire cutting method, Figure 3 is a side view showing the case where the printed board is bent, and Figures 4 and 5 are side views showing the case where the lead wires are cut. A side view showing a bent case;
FIG. 6 is an overall configuration diagram showing an embodiment of the present invention;
Fig. 7 is an explanatory diagram for explaining the order of cutting the lead wire, Fig. 8 is an explanatory diagram showing the operation of the cutting blade and sensor, and Fig. 9 is a diagram showing the positions of the cutting blade, sensor, and lead wire. FIG. 10, an arrangement diagram showing the relationship, is an explanatory diagram showing an example of cutting four printed boards at once. Code explanation P, P ₁ ~ _{P 4} ...Printed board, A...
...Back side of printed board, W...Work table, T
...template, H...head, N...cutting blade,
S...Sensor, MC...Microcomputer,
CPU...Central processing unit, MO...Monitor, KY...
...Keyboard, TY...Typewriter, F...Jig, L...Lead wire, R...Rail, U...Bottom side of printed board, M...Motor, E...Parts.

Claims (1)

[Scope of Claims] 1. In an automatic lead wire cutting device for a printed circuit board that automatically cuts each lead wire that protrudes from the back side of a printed circuit board to a predetermined length after mounting and soldering of components is completed. , a work table that receives the printed board with the back side facing a predetermined direction and moves a predetermined distance in a predetermined direction; and a work table that is installed on the back side of the printed board and moves a predetermined distance together with the work table. A sensor approaches the back of the printed board each time to measure the cut lead length of one of the lead wires and stops at a predetermined position, and a sensor moves horizontally a predetermined distance from the stopped position and stops. A head including cutting blades for cutting the one lead wire at a predetermined interval, and a control device for selectively positioning the head with respect to the work table. An automatic lead wire cutting device for printed circuit boards, which is characterized by: 2. The automatic lead wire cutting device for printed boards according to claim 1, wherein the control device comprises a microcomputer. 3. The automatic lead wire cutting device for printed boards according to claim 2, wherein when selectively cutting the lead wires, data to that effect is input to the microcomputer. Automatic lead wire cutting device. 4. The automatic lead wire cutting device for printed boards according to claim 1, wherein the cutting blades are nippers or scissors. 5. In the automatic lead wire cutting device for a printed board according to claim 1, the cutting blade includes a blade portion formed horizontally with respect to the printed board surface;
An automatic lead wire cutting device for a printed board, comprising an arm portion formed at a certain angle with respect to the printed board surface.