JPH0465760B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for shaping powders that harden under pressure.

[Prior Art] For example, electronic components such as tantalum codensors are formed by connecting wires to an element part, but this element part is made of dielectric powder that hardens when pressurized. Conventionally, it has been known to fill a die with the dielectric powder, and press the powder with a punch while inserting a wire into the powder in the die.

As a method for molding this type of powder, the method shown in, for example, Japanese Utility Model Application Publication No. 19614/1983 is known. This conventional powder molding method has upper and lower punches, the wire is held on the upper punch side, the lower punch is placed facing the lower part of the die filled with powder, and the tip of the wire is inserted from the upper punch. The wire is made to protrude by a predetermined amount and lowered toward the die, and when the wire comes into contact with the upper surface of the powder during the downward stroke of the upper punch,
The wire is fed out a predetermined length from the upper punch, and during this time the upper punch continues to descend while the lower punch is raised to pressurize the powder.

[Problems to be Solved by the Invention] By the way, if the wire inserted into the powder has a certain degree of rigidity, as described above,
Even if the wire is inserted and the powder is pressed by the upper and lower punches during a series of lowering movements of the upper punch, no particular problem arises. However, as mentioned above, when using a relatively thin wire diameter and fairly flexible wire such as a tantalum capacitor, the wire may be bent due to resistance when inserted into the powder.

Here, the greatest force is applied to the wire during insertion into the powder when the tip of the wire enters the powder. In order to prevent the wire from bending at this time, the length of the wire protruding from the upper punch may be shortened. Even if the wire is flexible, if the length of the wire protruding from the upper punch is kept extremely short, its strength will be significantly improved and it will be able to withstand resistance during insertion into the powder. However, if the length of the wire protruding from the upper punch is too short, the upper punch will come into contact with the powder immediately after the wire is inserted into the powder. When this wire is fed out from the upper punch, there is no escape part corresponding to the displacement volume by the wire, and an extremely large resistance is applied when this wire is fed out, which also causes the wire to bend.

Also, if the powder is pressurized from above and below at the same time after inserting the wire, a sudden pressure will be applied to the powder, and an excessive compressive force will be applied to the wire inserted inside, causing the wire to bend. , there is a risk that it may be pushed up and deformed. In this way, a proposal to prevent the wire from bending or deforming when pressurizing powder was proposed in 1973.
This was done in Publication No. -82190. According to this proposal, by bending the wire protruding from the upper punch, the embedding center is shifted from the pull-out center, and this bent portion receives the compressive force that is applied during pressurization. It consists of

With this configuration, bending of the wire during pressure molding can be suppressed to some extent, but it is necessary to bend the wire, and there is a risk that the wire may bend due to resistance when inserted into the powder. That is, both of the conventional techniques, JP-A-48-19614 and JP-A-51-82190, have the disadvantage that bending and deformation of the wire cannot be reliably prevented during the entire process of powder molding.

The present invention has been made in order to solve the problems in the prior art as described above, and the present invention is designed to prevent the wire from bending during the entire process from the start of inserting the wire into the powder to the end of pressure molding of the powder. Tsutari,
The purpose is to prevent it from deforming.

[Means for Solving the Problems] In order to achieve the above-mentioned object, the present invention fills a die with powder that hardens under pressure, and pressurizes the powder with a wire inserted into the powder in the die. In this method, the wire is lowered with the wire slightly protruding from the upper punch, and the upper punch is placed in a position where it faces the powder in the die with a small gap. a wire insertion step of inserting a first stage of wire into the powder, then inserting a second stage of inserting the wire into the powder to a predetermined length while holding the upper punch in the position; The powder is covered with a punch to prevent it from overflowing from the die, the lower punch is raised to apply the first stage of pressure to the powder, and the lower punch continues to rise. This method is characterized by a powder pressurizing step in which the powder is pressurized from above and below by lowering the upper punch while pressing the powder from above and below.

[Operation] According to the method of the present invention, the step of inserting the wire into the powder in the die is divided into a second stage. First, in the first step of insertion, the tip of the wire is made to protrude by a small length from the upper punch, and the upper punch is lowered to allow the tip of the wire to enter the powder. By allowing the wire to protrude a small length from the upper punch in this way, even a flexible and brittle wire can have the strength necessary to insert it into the powder. Can be inserted straight into powder. After the tip of the wire enters the powder, the upper punch is held in a stopped state before it comes into contact with the powder, and the second stage of insertion is performed by inserting the wire to a predetermined length. . This ensures that the powder escapes when the wire is pushed away, allowing the necessary amount of wire to be inserted smoothly without resistance.

When this wire insertion process is completed, the upper punch is moved to a position where it contacts the powder of the die, and from this state the pressurizing process is started. Pressing of this powder is also carried out in two stages. First, in the first stage of pressurization, the upper punch is kept covering the top surface of the powder.
It is performed by pushing the lower punch upward. As a result, the powder starts to harden from the bottom side and gradually moves upward. When the powder hardens to some extent, the tip of the wire inserted into the powder is fixed. In this state,
The second stage of pressurization is performed by lowering the upper punch while continuing to raise the lower punch. In this way, in the first stage, since the powder is pressurized only by the lower punch, no sudden pressurizing force is generated on the powder and no unreasonable force is applied to the wire. Therefore, there is no risk that the wire will bend or deform when pressurized.

[Example] Hereinafter, an example of the present invention will be described in detail based on the drawings.

First, FIG. 1 shows the overall structure of a molding apparatus for carrying out the pressure molding method according to the present invention.

In the figure, reference numerals 1 and 1 indicate guide rods installed upright on a base 2. A table 4 supporting a lower punch unit 3 is attached to the guide rod 1, and an upper punch plate 5 is moved by an elevating drive means 6. It is installed so that it can be raised and lowered. A punch unit 7 and a feeding means 9 for a wire 8 are mounted on the upper punch plate 5.

The lower punch unit 3, as shown in FIG. Then, below the die 10, a lower punch 12 is placed under a lower punch guide 1.
3 so that the tip of the lower punch 12 can face into the filling part 10a of the die 10. In order to move the lower punch 12 up and down, the lower punch 12 is provided with a push-up rod 14 that is driven up and down by a lifting drive means (not shown) such as a cam mechanism. Return springs 15 and 16 act on the lower punch 12 and the push-up rod 14, respectively.

Next, as shown in FIG. 3, the upper punch unit 7 is constructed by attaching a punch holder 22 with an upper punch 21 attached to its tip to a support block 20 vertically disposed on the upper punch plate 5. A guide 23 is attached to the support block 20 in its axial direction, and a pipe 24 through which the wire 8 is inserted is attached to the guide 23. A lower blade 25 is attached to the upper punch 21, and an upper blade 26 for cutting the wire 8 by sliding horizontally on the lower blade 25.
is attached to the upper blade holder 27, and an actuating rod 28 is provided to operate the upper blade holder 27. The actuating rod 28 is held in a state where the wire 8 is not cut by a spring 29, and when the actuating member 30 (see FIG. 1) is actuated to push the actuating rod 28, the upper blade 26 moves in the horizontal direction. This allows the wire 8 to be cut.

Further, the wire feeding means 9 includes chuck members 34 and 35 attached to first and second chuck bases 32 and 33 which are mounted on a rod 31 erected on the upper punch plate 5 so as to be movable up and down. Among these chuck members 34 and 35, the first chuck member 34 is for pulling down the wire 8, and the second chuck member 35 is for pulling down the wire 8 by a predetermined amount when the upper punch plate 5 is raised. It is designed to raise only. Each of these chuck members 34, 35 is configured to be able to be displaced between a chuck position with respect to the wire 8 of a solenoid (not shown) and a chuck release position.

Therefore, between the chuck base 34 and the upper punch plate 5, and the chuck bases 34, 35,
Springs 36 and 37 are compressed between them, respectively. As a result, the chuck bases 34 and 35 move up and down following the upper punch plate 5, and when the upper punch plate 5 descends, the chuck base 34 is further compressed by the spring 36. The chuck base 34 is moved downward in a direction approaching the upper punch plate 5, and the wire 8 can be inserted into the dielectric powder P in the die 10 by the movement of the chuck base 34. There is. In addition, when the upper punch plate 5 is raised, the chuck base 35
The wire 8 is lowered by a predetermined amount against a spring 37, so that when the upper punch 21 is in the raised position, the wire 8 can be pulled out so that the tip thereof slightly protrudes from the upper punch 21. It's summery.

In order to lower the chuck base 34 against the spring 36 in this manner, bayonet actuating means 38 are provided. The plug actuating means 38
has a lever 40 that swings about a fulcrum 39, one end of which is connected to the chuck base 34, and the other end of which is connected to a reciprocating shaft 41.
It has become possible to approach and separate from the An adjustment bolt 42 is connected to the reciprocating shaft 41, and by screwing in and out the adjustment bolt 42, the movement stroke of the chuck base 34 can be adjusted.

In order to lower the chuck base 35 against the spring 37, stopper bolts 44, 44 are attached to the top plate 43 attached to the upper end of the guide rod 1.
is screwed in. The stopper bolt 44 is configured so that its tip can come into contact with the chuck base 35, and when the upper punch plate 5 rises in this state, the chuck base 35 moves relatively toward the upper punch plate 5. It's summery. In addition, this chuck base 35
The amount of movement can also be changed by threading the stopper bolt 44 in and out as appropriate.

Further, an elevating drive means 6 for elevating and lowering the upper punch unit 7 and the wire feeding means 9 mounted on the upper punch plate 5 supporting the upper punch unit 7 is constructed as shown in FIG. That is, the upper punch plate 5 has a roller receiver 4.
5 is installed, and the roller mounting part 45a formed in the roller receiver 45 has a roller 4 attached to the other end of the operating lever 47, one end of which is pivotally connected to the fulcrum part 46.
8 is inserted. A connecting rod 49 is attached to the middle part of the operating lever 47.
The other end of the connecting rod 49 is connected to an upper punch lever 51 which is swingably supported on a fulcrum 50. Further, a pressure lever 52 is attached to the fulcrum 50, and the pressure lever 52 has a contact portion 54 that comes into contact with the tip of a pressure stroke adjustment bolt 53 that is screwably attached to the upper punch lever 51. By threading the bolt 53 in and out as appropriate, the distance d between the tip of the bolt 53 and the contact portion 54 can be adjusted.
Further, a cam plate 55 is provided in order to swing the upper punch lever 51 and the pressure lever 52 about the fulcrum 50.
The cam follower 5 attached to the upper punch lever 51 is
A grooved cam portion 55a for swinging the cam follower 57 of the pressure lever 52 is formed, and an end cam portion 55b for swinging the cam follower 57 of the pressure lever 52 is provided.

The apparatus for pressure-molding powder is constructed as described above, and a method for pressure-molding powder will now be described with reference to FIGS. 5 and 6.

First, with the upper punch plate 5 held in the raised position and the wire 8 slightly protruding from the upper punch 21, a predetermined amount of dielectric material is placed in the filling part 10a of the die 10 mounted on the table 4. Powder P is supplied.

Therefore, the wire 8 is chucked by the first chuck member 34, and the wire 8 is chucked by the second chuck member 35.
is in the state where the chuck is open and the lifting drive means 6 is moved.
performs the first stage insertion operation. In this first stage insertion, as shown in FIG. lower until they are facing each other with a slight gap between them. At this time, the chuck member 34 descends following the lowering of the upper punch plate 5, so that the tip of the wire 8 descends to a position where it is inserted into the dielectric powder P. here,
Since the wire 8 only slightly protrudes from the upper punch 21, even if there is considerable resistance when it is inserted into the dielectric powder P, it can be inserted smoothly without bending or deforming. Can be inserted.

While maintaining the upper punch 21 with a slight gap between it and the dielectric powder P, insert the upper punch 21 into the operating means 3.
The reciprocating shaft 41 at 8 is raised to swing the lever 40 about the fulcrum 39, and the chuck base 32 attached to the other end of the lever 40 is lowered along the rod 31 against the spring 36. As a result, the chuck member 34 attached to the chuck base 32 is lowered and the chuck member 3
4 is pulled down. As a result, the second stage of insertion shown in FIG. 5b is performed, and the wire 8 is pushed into the dielectric powder P by a predetermined length. Here, when inserting the wire 8 into the dielectric powder P, the upper punch 2
By separating the wire 8 from the dielectric powder P, the dielectric powder P is pushed away when the wire 8 is inserted, but a relief part is formed in the dielectric powder P. Even during the second stage of insertion, in which the wire 8 is inserted by a predetermined length, the wire 8 is inserted smoothly without bending.

When the insertion of the wire 8 is completed in this way, the lifting drive means 6 is operated to lower the upper punch plate 5 slightly to cover the upper part of the filling part 10a of the die 10 as shown in FIG. 5c. Do it like this. In this way, the filling part 1 in the die 10
By covering 0a, it becomes possible to prevent the dielectric powder P from overflowing from the die 10 in the pressurizing process described later. The upper punch 2 is placed at the insertion position of the wire 8 described above and at a position covering the upper part of the filling part 10a of the die 10.
1, the upper punch lever 51 connected to the cam follower 56 is swung by guiding the cam follower 56 along the groove cam portion 55b of the cam plate 55, and the connecting rod attached to the upper punch lever 51 is lowered. By lowering 49,
This is accomplished by rotating the operating lever 47 connected to the connecting rod 49 about the fulcrum 46, thereby lowering the upper punch plate 5.

In this state, as shown in FIG. 5d, operate the push-up rod 14 to
The lower punch 12 connected to the die 10 is raised to apply pressure to the dielectric powder P in the die 10 to perform the first stage of pressure. By performing this first stage pressurization only with the lower punch 12, it is possible to prevent sudden pressurizing force from acting on the dielectric powder P.
This causes the dielectric powder P to gradually harden from below. As a result, there is no risk that the wire 8 embedded in the dielectric powder P will be deformed due to excessive force being applied to it.

Then, when the aforementioned lower punch 12 rises to a predetermined position, the dielectric powder P hardens to some extent, and the tip portion of the wire 8 also begins to harden, a second stage of pressure is applied. In this second stage of pressurization, as shown in FIG. The dielectric powder P
The molding is done by pressing tightly.

In this way, the lower punch 12 is operated independently up to the middle of its stroke, and the die 10 is
The dielectric powder P inside starts to harden from the lower part, and after this dielectric powder P hardens to some extent and the wire 8 becomes stable, the upper punch 21 pushes the wire 8 downward in the direction opposite to the pressing direction of the lower punch 12 described above. By operating the wire 8 and applying pressure in two stages to harden from the top and bottom, no undue force is applied to the wire 8, and the wire 8 is cured smoothly.
Furthermore, it is possible to perform tight curing molding as a whole.

Here, in the final stroke of the upper punch 21, the cam follower 56 of the upper punch lever 51
is located in the relief part of the grooved cam part 55a, and the cam follower 57 in the pressure lever 52 is located in place of this.
is guided and swung along the end cam portion 55b, and the contact portion 54 provided on the pressure lever 52 contacts the bolt 53 of the upper punch lever 51, pushing down the bolt 53, and the upper punch lever 51 further rotates, and the dielectric powder P is pressed by the upper punch 21.

After the molding of the dielectric powder P is completed as described above, as shown in FIG.
8 and moves the upper blade 26 in the horizontal direction to cut the wire 8, thereby completing the forming, after which the workpiece can be taken out.

The timing chart of the operation of each member mentioned above is as shown in FIG.

After the dielectric powder is molded in this way, preparations for the next molding operation are made. That is, when the above-described cutting is performed, the wire 8 is chucked by the second chuck member 35, the chuck by the first chuck member 34 is released, and the upper punch plate 5 is raised in this state. . As a result, the tip of the wire 8 is held at the previous cutting position. However, when the upper punch plate 5 approaches the stroke end, the second chuck member 35 comes into contact with the stopper bolt 44, and the chuck member 35 no longer rises, and the wire 8 chucked by it also moves to that position. Stop at. On the other hand, since the upper punch plate 5 further rises to its stroke end, the tip of the wire 8 extends to a state where it slightly protrudes from the upper punch 21 of the upper punch unit 7 attached to the upper punch plate 5. It returns to its original state.

As described above, the wire 8 is sequentially inserted into the dielectric powder P and the dielectric powder P is press-molded.

Thus, the final downward stroke of the upper punch 21, ie, the stroke of the upper punch 21 in the molding process of the dielectric powder P, is variable. To change this stroke, bolt 5
3 by screwing in and out as appropriate, the bolt 53
The distance d (see FIG. 4) between the tip of the pressure lever 52 and the contact portion 54 of the pressure lever 52 may be changed.
If this distance d is made small, the contact portion 54 of the pressure lever 52 will come into contact with the bolt 53 at an early stage after the rotation starts, and the upper punch lever 51 to which the bolt 53 is attached will come into contact with the bolt 53.
The amount of rotation of the upper punch 2 increases.
1 stroke becomes longer. On the other hand, when the distance d is increased, the amount of rotation of the upper punch lever 51 by the pressure lever 52 becomes smaller, and the stroke of the upper punch 21 becomes shorter. Therefore, when replacing the die and upper and lower punches according to the dimensions and shape of the molded product, by adjusting the gap d mentioned above, the pressure stroke at the final stage of the upper punch 21 can be adjusted to 0.
By making this adjustment, it becomes possible to tightly press the dielectric powder P, regardless of the size or shape of the molded product. , the quality can always be constant and good.

[Effects of the Invention] As detailed above, the present invention improves strength by slightly protruding the wire from the upper punch when inserting the wire into the powder when molding the powder. 2. Insert the wire into the powder with the upper punch held away from the powder and insert the wire into the powder to the specified length.
Inserting the wire in stages prevents the wire from bending due to resistance during insertion into the powder, etc.
The wire can be inserted into the powder smoothly and reliably without deformation, and the powder is pressurized after the wire is inserted, with the first stage of pressure being pushed up by the lower punch, and after the pressure has progressed to a certain extent. Since two stages of pressure are applied, including the second stage of pressure using the upper and lower punches, there is no risk that the wire inserted into the powder will be deformed due to sudden pressure, etc., and the wire can be inserted easily. During the entire process from start to finish, relatively flexible and brittle wires can be used without the risk of bending or deforming the wires.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing an example of the configuration of an apparatus for implementing the molding method of the present invention, Fig. 2 is a sectional view of the lower punch unit, Fig. 3 is a sectional view of the upper punch unit, and Fig. 4 is an elevational view. Explanatory diagram of the configuration of the driving means, fifth
Figures a, b, c, d, e, and f are explanatory diagrams showing the process of molding an electronic component, and Fig. 6 is a timing chart of the molding process. 3... lower punch unit, 4... table, 5
...Upper punch unit, 8...Wire, 9...Wire feeding means, 10...Dice, 12...Lower punch, 13...Lower punch guide, 21...Upper punch, 22...Punch holder, 41... ... Adjustment bolt, 47 ... Operating lever, 51 ... Upper punch lever, 52 ... Pressure lever, 53 ... Bolt, 54
...Abutting portion, 55...Cam plate, 55a...Groove cam portion, 55b...End face cam portion.

Claims (1)

[Claims] 1 Fill the die with powder that hardens under pressure,
In a method of pressurizing the powder in the die with a wire inserted therein, the wire is slightly protruded from the upper punch and lowered, and the upper punch is inserted into the powder in the die. The first stage of the wire is inserted into the powder at a position facing the upper punch with a slight gap, and then the wire is inserted into the powder to a predetermined length while the upper punch is held in that position. A wire insertion step is performed to insert the second stage of the powder, and the upper punch covers the powder to prevent the powder from overflowing from the die, and the lower punch is raised to insert the powder into the first stage. A powder pressurization process comprising applying pressure, and then performing a second stage of pressurization in which the upper punch is lowered while the lower punch continues to rise to apply pressure to the powder from above and below. .