JPH0610004A - Permanent magnet powder filling device - Google Patents

Abstract

(57) [Summary] [Purpose] To prevent wear of the upper surface of the mold and to adjust the gap between the mold and the magnetic pole, improving maintainability. Even if the width of the opening of the molding space is narrow, it is possible to uniformly and uniformly fill the molding space with the permanent magnet powder in a very short time. A solenoid coil 20 slidable along an upper surface of an opening of a cylindrical molding space 18 of a mold and having a central axis direction aligned with a depth direction of the molding space, and swingable in a vertical plane above the solenoid coil 20. Lever 26, a magnetic pole 32 that can be moved up and down in the coil, a spring 30 that gives upward repulsive force to the lever, an air cylinder 34 for pushing up on the lever base end side, and a power supply that supplies an alternating current to the coil. It is equipped with a device. A sleeve 28 with a flange is provided at the tip of the lever, a spring is interposed between the flange and the coil bobbin, and a magnetic pole is attached to the lower end of the sleeve.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has a solenoid coil slidable along an upper surface of an opening of a molding space of a mold, and a magnetic pole movable up and down inside the solenoid coil. The present invention relates to an apparatus for uniformly filling a molding space with a permanent magnet powder in a short time.

[0002]

2. Description of the Related Art In order to develop good magnetic properties, permanent magnet powder is usually filled in the molding space of a mold and compression molded by a press molding machine. ing. In compression molding, the filling of the permanent magnet powder into the mold molding space is performed exclusively by gravity falling by gravity. In other words, a bottomless powder supply mechanism that slides on the upper surface of the die that forms the mold allows the powder to drop naturally from the opening of the molding space to fill it, and slide the powder supply mechanism to remove excess powder. A method of filling a certain amount of powder into the molding space of a mold by a sliding method is generally used.

If the powder has good fluidity and the opening area of the die molding space is considerably large, it is possible to fill it by such a method, but especially the fluidity is poor such as rare earth bonded magnet powder. When the area or width of the opening is small, it is difficult to sufficiently fill the powder by simply sliding the powder supply mechanism along the upper surface of the mold. Therefore, a device for applying a slight vibration to the mold to fill the mold, a device for forcibly pressing the powder by providing a blade (pushing member) for forced filling in the upper part of the molding space, and the like may be used.

However, in a device for filling a mold by applying slight vibration, the filling rate is likely to change depending on the state and shape of the powder, and there is a possibility that the tightening of the bolts and the like of the device may become loose due to the vibration. However, the filling efficiency is not improved so much and the reproducibility of the filling amount is poor. In addition, in a device for forced filling using blades, not only the time required for filling is very long, but also automation of powder filling in the pressing process is difficult and manufacturing efficiency is extremely poor. As a result, the shape of the filled powder is locally different from the shape before (before filling), which makes it difficult to perform uniform quantitative filling, resulting in uneven weight distribution and uneven density distribution during molding. .

In order to improve these drawbacks, the applicant of the present invention first installs a solenoid coil in the vicinity of the opening of the molding space of the mold in such a direction that its central axis direction substantially coincides with the depth direction of the molding space. At the same time, a method has been proposed in which a magnetic pole is installed in the solenoid coil and an alternating current is supplied to the solenoid coil to fill the permanent magnet powder above the opening into the molding space (Japanese Patent Laid-Open No. 2-7506). reference). With this filling technique, the permanent magnet powder vibrates by the application of an alternating magnetic field, and even permanent magnet powder having poor fluidity can be efficiently and uniformly filled in a narrow molding space in a short time.

[0006]

In order to carry out the above filling technique using an alternating magnetic field, it is necessary to dispose a solenoid coil and a magnetic pole on the upper surface of the opening of the molding space. And after filling, when performing molding, they must be removed because they become an obstacle. Therefore, in the prior art, the magnetic pole is fixed to the solenoid coil, and it is configured to be slidable along the upper surface of the opening of the molding space.

In order for the magnetic pole to slide, a gap is required especially between the magnetic pole and the center rod of the mold. This gap is set very small (usually 0.15 mm or less),
Permanent magnet powder gets into the gap, or the permanent magnet powder that tries to enter (especially when the particle size is large) is gathered in the gap (because the magnetic field is strongest in a narrow gap) and the mold is covered. A phenomenon occurs, and it is easy to cause a problem that the charged permanent magnet powder does not completely enter the mold. If this happens, the permanent magnet powder will not be supplied in a fixed amount, causing variations in the dimensions of the molded product.

Further, when the solenoid coil and the magnetic pole slide together, if the permanent magnet powder is trapped in the gap, the lower surface of the magnetic pole and the upper surface of the die are extremely worn.
Then, the gap between the die (center rod) and the magnetic pole widens, and it becomes easier for permanent magnet powder to enter. Therefore, it is necessary to replace the parts. Actually, it was necessary to replace the parts when there was a gap of 0.3 mm or more. When exchanging parts, adjust the gap between the die and the magnetic pole (for example, 0
(Within ~ 0.15 mm) was required, and the work was extremely troublesome.

The object of the present invention is to solve the above-mentioned drawbacks of the prior art, prevent wear of the upper surface of the mold, and eliminate the need to adjust the gap between the mold and the magnetic pole, thereby improving the maintainability. Moreover, even if the opening area of the molding space of the mold is small or the width of the opening is narrow, a fixed amount of permanent magnet powder can be uniformly and uniformly filled in the molding space in an extremely short time. An object of the present invention is to provide a permanent magnet powder filling device that can be immediately applied.

[0010]

SUMMARY OF THE INVENTION The present invention is a solenoid that is slidable along an upper surface of an opening of a cylindrical molding space of a mold and is installed with its central axis direction substantially aligned with the depth direction of the molding space. A coil, a lever pivotally mounted above the solenoid coil so as to be swingable in a vertical plane, a magnetic pole that engages with the tip of the lever and can move up and down in the solenoid coil, and the magnetic pole Permanent magnet powder including a spring that imparts upward resilience, an air cylinder for pushing up the lever that is provided at the base end of the lever, and a power supply device that supplies an alternating current to the solenoid coil. It is a filling device. As a specific mounting structure of the magnetic pole, for example, it is preferable that a flanged sleeve is provided at the tip of the lever, a spring is interposed between the flange and the coil bobbin, and the magnetic pole is mounted at the lower end of the sleeve.

Further, without using a lever and an air cylinder,
A structure may be used in which the magnetic pole is supported by a spring so that the magnetic pole can be moved up and down in the solenoid coil.

[0012]

As is well known, a permanent magnet powder having a certain coercive force is sensitive to a magnetic field. Naturally, these permanent magnet powders have the property of being attracted in the direction of a strong magnetic field. When a solenoid coil is installed near the opening of the molding space of the mold in such a direction that the central axis is substantially aligned with the depth direction of the molding space and an alternating current is supplied, an alternating magnetic field is applied, which causes an oscillating force on the permanent magnet powder. And movement power is given. This moving force acts in the direction of attracting the permanent magnet powder into the molding space, and the permanent magnet powder is sequentially filled into the space while vibrating.

The magnetic pole in the solenoid coil concentrates the AC magnetic flux, and the concentrated magnetic flux from the magnetic pole further concentrates in the molding space to strengthen the magnetic flux distribution in the depth direction of the die, that is, the magnetic field gradient, Improves filling efficiency. Since this filling is performed by a magnetic attraction force that is much larger than the force due to natural fall, etc., even if the opening area of the molding space of the mold is small or the width of the opening is extremely narrow, it takes a very short time. Is done smoothly. Moreover, unlike the conventional forced filling with a blade or the like, the permanent magnet powder is filled almost uniformly without being broken.

When sliding on the upper surface of the mold, the magnetic pole rises due to the elastic force of the spring to form a gap with the mold. This prevents wear of the mold and the like. When installed in the molding space, the magnetic pole is pushed down against the elastic force of the spring by the action of the air cylinder or the electromagnetic force of the solenoid coil, and it sticks to the upper surface of the mold (center rod) and remains in that state. Powder filling is performed. Therefore, there is no space for the powder to enter, and the powder can be smoothly and quantitatively filled in the molding space.

[0015]

1 is a front sectional view showing an embodiment of a filling apparatus according to the present invention, and FIG. 2 is a plan view thereof. This is drawn together with a part of a mold for obtaining a cylindrical (including ring-shaped) molded body. The die part vertically slides in a die 10 having a cylindrical hole in the center, a center rod 12 arranged with a gap in the center, and a cylindrical gap between the die 10 and the center rod 12 in the vertical direction. And a movable lower cylindrical punch 14. The cylindrical space formed by these three members constitutes the molding space 18. The molding space 18 is filled with permanent magnet powder, and a cylindrical upper punch (not shown) is inserted and pressed from above to perform compression molding. Although the structure of the die of the press molding machine is basically the same as that of the conventional case, in the present invention, the die 10 and the center rod 12 of the members constituting the die are made of a magnetic material, and the lower punch is used. 14 (also the upper punch) is made of a non-magnetic material.

In the present invention, the solenoid coil 20 is arranged on the upper surface of the opening of the cylindrical molding space 18 of the mold. The solenoid coil 20 is slidable along the upper surface of the mold, with the central axis of the solenoid coil 20 substantially aligned with the depth direction of the molding space 18. Although not shown, it is actually attached to a horizontal drive mechanism such as an air cylinder.

Here, the solenoid coil 20 has a coil bobbin 22 having flanges on the upper and lower sides and a predetermined winding 2 formed on a coil bobbin 22.
4 is applied, and the inner diameter of the coil bobbin 22 is set to substantially match the outer diameter of the molding space 18.
At a position above the upper flange of the solenoid coil 20, a lever 26 is pivotally supported by a pin 27 so as to be swingable in a vertical plane. The tip of the lever 26 is bifurcated and shaped to extend along the half circumference of the inner surface of the solenoid coil 20.

A flanged sleeve 28 is loosely fitted in the upper portion of the solenoid coil 20, and a spring 30 is interposed between the lower surface of the flange of the sleeve 28 and the upper surface of the coil bobbin. From the lower end of the sleeve 28, the solenoid coil 2
The magnetic pole 32 that can move up and down within 0 is suspended, and the elastic force of the spring 30 imparts an upward elastic force to the magnetic pole 32. The magnetic pole 32 has a substantially cylindrical shape having a diameter equal to or smaller than the diameter of the center rod in the center of the mold. The sleeve 28 has a hole 31 penetrating in the longitudinal direction, which serves as a supply path for the permanent magnet powder. As described above, the tip of the lever 26 is bifurcated,
The tip of the sleeve covers and presses the pins 29 on both sides of the upper portion of the sleeve 28. Further, an air cylinder 34 for pushing up the lever is provided at the base end portion of the lever 26, and the base end portion of the lever 26 can be driven upward by the air cylinder 34. A power supply device (not shown) that supplies and controls an alternating current is connected to the solenoid coil 20.

The filling of the permanent magnet powder is performed by the procedure as shown in FIG. FIG. 3A shows a state in which the molded product is discharged after the molding, and the next step starts from this state.
While the magnetic pole 32 is rising due to the elastic force of the spring 30, the solenoid coil 20 is slid in the direction of the white arrow M to form the molding space 1 as shown in FIG. 3B.
Position 8 above. Therefore, during the sliding operation, a gap is maintained between the magnetic pole 32 and the mold (center rod 12). Next, the air cylinder 34 is driven,
The rear end of the lever 26 is pushed up. Then spring 30
The sleeve 28 is pushed down against the repulsive force of the magnetic pole 32, and the magnetic pole 32 also descends, and the lower surface thereof comes into close contact with the upper surface of the center rod 12 (see C in FIG. 3). In this state, the permanent magnet powder is quantitatively supplied from above the sleeve 28 through the hole 31. After the permanent magnet powder enters the solenoid coil 20, an alternating current is supplied to the solenoid coil 20 to fill the molding space 18 of the mold with the permanent magnet powder.

The frequency of the alternating current used is not particularly limited, but may be a normal commercial frequency. By passing an alternating current through the solenoid coil 20, alternating magnetic field lines are generated, and an alternating magnetic field is formed in the molding space 18 or the like. Since the magnetic pole 22 is arranged at the center of the solenoid coil 20, it is possible to concentrate the alternating magnetic field in the molding space 18, and even with a weak current, the permanent magnet powder 2 can be formed.
4 can be effectively sucked into the molding space 18. The shape of the lines of magnetic force changes depending on the material (magnetic material or non-magnetic material) of the mold constituent member, but this alternating magnetic field magnetically attracts the permanent magnet powder to the inside of the molding space 18 to generate the alternating magnetic field. While reacting and repeating complicated vibrations, even a very narrow gap is filled in a short time. Therefore, thereafter, the supply of the alternating current to the solenoid coil 20 is stopped. When the lever pushing force of the air cylinder 34 is released, the magnetic pole 32 is lifted by the elastic force of the spring 30, and a gap is created between the magnetic pole 32 and the die (center rod 12). In this state, the solenoid coil 20 is slid back to the original position, and the upper punch is lowered and pressed to perform compression molding.

Since the powder filling effect in the present invention is mainly due to the magnetic properties of the powder, if it is a permanent magnet powder, it is a samarium-cobalt type magnet powder, a ferrite type, an alnico type or neodymium. Similar results can be obtained with any of the iron-boron system and the like. The shape of the molding space is particularly effective when it is a thin-walled cylindrical shape or a thin-walled plate shape, but it can also be applied to any other shape. It goes without saying that it can be applied not only to powder for sintered magnets but also to powder for bonded magnets (powder kneaded with resin).

Although one preferred embodiment of the present invention has been described in detail above, the present invention is not limited to this.
In the above embodiment, using the lever and the air cylinder,
Although the lever is moved by the pushing force of the air cylinder to lower the magnetic pole first, the magnetic pole may be suspended by a spring without using the air cylinder or the lever. In this case, first, by energizing the solenoid coil, the magnetic pole is attracted to the center rod by a magnetic attraction force, and then the permanent magnet powder is directly supplied to fill the molding space. But in reality,
If the AC magnetic field is not applied after the permanent magnet powder has been placed in the solenoid coil, some of the powder may scatter, so the device configuration described in detail in the above embodiment is preferable.

[0023]

As described above, according to the present invention, the magnetic pole is installed in the solenoid coil, and when the solenoid coil moves on the upper surface of the die, the magnetic pole is floated and the magnetic pole is lowered at a predetermined die position. Since the magnetic field and the center rod do not form a gap during filling because the AC magnetic field is applied, even if the opening area of the molding space is small or the opening is extremely narrow, Magnet powder can be quickly and smoothly filled into the molding space, and permanent magnets can be molded very efficiently. In addition, when moving the solenoid coil, etc., a gap is created between the magnetic pole and the mold, so the upper surface of the mold is not worn and the frequency of parts replacement is greatly reduced. Maintenance work is greatly improved by eliminating the need to adjust the gap between the magnetic pole and the magnetic pole.

Moreover, since the permanent magnet powder is filled by a magnetic attraction force instead of forcing it mechanically,
The shape of the original powder is maintained as it is, so that the density distribution is uniform, the weight of the compact is constant, and there is an advantage that permanent magnets having uniform characteristics can be mass-produced. Further, since the present invention is only installed on the upper part of the mold, it can be applied to any existing press molding machine, and various permanent magnets can be manufactured regardless of the particle size and state of powder. It can be used in the field.

[Brief description of drawings]

FIG. 1 is a front sectional view showing an embodiment of a permanent magnet powder filling device according to the present invention.

FIG. 2 is a plan view thereof.

FIG. 3 is an operation explanatory diagram thereof.

[Explanation of symbols]

 10 Die 12 Center Rod 14 Lower Punch 18 Forming Space 20 Solenoid Coil 22 Coil Bobbin 24 Winding 26 Lever 28 Sleeve 30 Spring 32 Magnetic Pole

Claims (3)

[Claims] 1. A solenoid coil, which is slidable along an upper surface of an opening of a cylindrical molding space of a mold and is installed in a direction in which a central axis direction substantially coincides with a depth direction of the molding space,
A lever pivotally supported in the vertical plane above the solenoid coil, a magnetic pole that engages with the tip of the lever and can move up and down in the solenoid coil, and an upward bullet on the magnetic pole. A spring for imparting repulsive force, an air cylinder for pushing up the lever, which is provided at the base end of the lever,
A permanent magnet powder filling device comprising: a power supply device that supplies an alternating current to the solenoid coil. 2. The filling device according to claim 1, wherein a sleeve with a flange is provided at the tip of the lever, a spring is interposed between the flange and the coil bobbin, and a magnetic pole is attached to the lower end of the sleeve. 3. A solenoid coil, which is slidable along an upper surface of an opening of a cylindrical molding space of a mold and is installed in a direction in which a central axis direction substantially coincides with a depth direction of the molding space.
A magnetic pole that can move up and down in the solenoid coil, and a spring that imparts upward resilience to the magnetic pole,
A permanent magnet powder filling device comprising: a power supply device that supplies an alternating current to the solenoid coil.