JP3335299B2 - Powder molding machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a powder molding machine for compression-molding a powder by using a twin-screw roll compression molding machine and a continuous extruder for supplying the powder thereto. The present invention relates to a degassing powder molding machine.

[0002]

2. Description of the Related Art This type of powder molding machine is disclosed in Japanese Utility Model Laid-Open No. 4-26.
No. 697 (Publication 1), Japanese Unexamined Patent Publication No. 3-193129 (Publication 2), Japanese Utility Model Laid-Open Publication No. 4-60394 (Publication 3)
As shown in FIG. 7, a screw 31 and a biaxial compression roll 3 are provided at an outlet of a powdery raw material (powder) hopper 32.
Generally, a configuration in which the rollers 37 and 37 are provided continuously is used, and the powder in the hopper 32 is forcibly fed between the rollers 37 and 37 by rotating the screw 31 by the motor 36, and the powder is transferred between the rollers 37 and 37. To obtain a plate-shaped or rod-shaped molded product. The molded product is crushed to a predetermined particle size by a granulator.

In this powder molding machine, as disclosed in the above publications, for example, as shown in FIG. 7, a degassing cylinder 34 in which a casing of a screw 31 is lined with a ventilation plate 33,
This deaeration cylinder 34 is connected to a vacuum pump 35 so that the deaeration cylinder 3
There is a technique for deaeration of the inside of the screw feeder 4, that is, the inside of the screw feeder. According to this technique, the air in the powder in the screw feeder is deaerated by deaeration, and the powder having a reduced porosity is immediately compression-molded by the roll 37. A strong molded product can be obtained.

[0004]

The screw feeders described in the above publications each have one screw 31,
When degassing is performed in the single-screw feeder, the powder is compressed by degassing, and this compression causes a phenomenon in which the powder adheres to the outer surface of the screw 31, thereby greatly reducing the transfer capability of the screw 31. In addition, if a plurality of screws 31 are used, the adhesion of the conveyed object is improved,
Publication 2 discloses that effect.

[0005] However, if the degassing force is increased to further reduce the porosity of the conveyed material, the adhesion of the powder is also increased, and it is possible to prevent the transfer capability from lowering even if a plurality of screws 31 are used. Is not possible, both rollers 37,
Since a uniform amount and density of powder are not supplied between 37, it is difficult to obtain a molded product having a constant property.

Japanese Patent Application Laid-Open No. Hei 3-187802 (Japanese Patent Laid-Open Publication No. HEI 3-187802) discloses that when a granular material is fed into a bag by a screw conveyer (feeder), the granular material is degassed in the screw feeder to reduce the density of the granular material. Techniques for reducing bulk have been disclosed. In this technology, a screw feeder is of a self-cleaning type having a plurality of shafts, thereby scraping powder particles that are to adhere to the screw blade surface and the inner surface of the casing, and performing effective deaeration and conveyance.

However, in this device, the entire outer peripheral surface of the pair of screws is covered with a filter, and it is not easy to remove the filter and inspect, clean, or replace the screws. Also, since the cross section of the filter is approximately cocoon-shaped and complicated, the production cost is high.

The first object of the present invention is to smoothly feed powder from a degassing screw feeder to a roll forming machine under the above circumstances, and to remove a filter when clogging occurs. The second task is to make it easy to perform

[0009]

In order to achieve the first object, the present invention focuses on the fact that the technology described in the above publication 4 can perform effective degassing and conveyance. A twin-screw roll compression molding machine is installed in front of the outlet of the casing, and the screw feeder forcibly feeds powder to the compression molding machine and deaerates the inside of the screw feeder. The feeder was a self-cleaning type in which a plurality of screws were arranged in parallel.

In the self-cleaning type, the outer surfaces of the screws and the outer surface of the screw and the inner surface of the casing come close to each other to scrape off the conveyed matter attached to the outer surface of the screw and the inner surface of the casing. For this reason, in the case of the self-cleaning type screw feeder, the powder is uniformly fed into the roll compression section without accumulating in the screw feeder, and the roll compression is also performed uniformly. In particular, the self-cleaning is effective because degassing causes the powder to shrink and adhere to the outer surface of the screw or the inner surface of the casing and easily accumulate.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As an embodiment of the deaeration means in the screw feeder, a deaeration chamber is formed in a casing of the screw feeder, and the deaeration chamber is formed by expanding a part of the casing. The outer surface of the bulging portion is an opening, the opening is closed by a lid, a filter is provided between the deaeration chamber and the screw, and the filter can be inserted into the deaeration chamber from the opening. A configuration that can be screwed to the casing may be employed.

With this configuration, when the filter is worn or clogged and is repaired or replaced, the filter can be easily removed from the opening by removing the lid, thereby improving the workability. Good. That is, the second problem is solved.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment is shown in FIGS. 1 to 4, and this embodiment 1 also comprises a twin-screw roll compression molding machine 2 installed in front of an outlet of a casing 3 of a screw feeder 1. FIG. The screw feeder 1 includes a hopper 5 for feeding powder, a screw 4, a casing 3 for covering the screw 4, and a motor 14 for rotating the screw 4.

As shown in FIGS. 2 and 4, two screws 4 are arranged in parallel, and a number of screw paddles 4b are externally fitted on a screw shaft 4a. Screw paddle 4b
As shown in FIG. 3A, the cross section is oval and twisted by 180 ° in the axial direction of the screw shaft 4a. The screw paddles 4b come close to each other and perform self-cleaning.

In addition, instead of this screw paddle 4b,
As shown in FIG. 3B, a kneading paddle 4c having an oval cross section and not twisted in the axial direction of the screw shaft 4a can be used. In this case, as shown in FIG. 4, the screw paddle 4b at the middle portion among the many screw paddles 4b.
Is desirably replaced with the kneading paddle 4c. The kneading paddle 4c is attached in the circumferential direction little by little toward the axial direction of the screw shaft 4a, and a slightly twisted (5-10 °) 4c ′ as shown in FIG.

The casing 3 is manufactured by casting as shown in FIGS. 2 (a) and 2 (b), the lower portion of the hopper 5 is expanded, and the lower surface thereof is closed with a lid 27 having an intake hole 26. The filter 28 is configured to be screwed at the boundary with the screw 4. At this time, the filter 28
The shape may be flat as shown in (a) or may be along the screw 4 as shown in FIG. Further, the outer peripheral edge of the screw paddle 4 b is made to approach the inner surface of the casing 3.

As shown in FIG. 1, the biaxial roll compression molding machine 2 includes two rolls 21 and 21 ',
Roll shafts 22, 22 'for supporting 1, 21', roll 21
And a drive motor (not shown) for rotating the roll 21 ′. The two rolls 2
The roll shafts 1, 21 'are arranged with a clearance so that the roll shafts 22, 22' are parallel. Roll 2
The side surfaces 1 and 21 'form the same plane. Since the roll 21 can be translated by the hydraulic cylinder 23, the roll 21 can be pressed against the roll 21 '. Further, since the drive motor is attached to the roll 21 ', the roll 21' is a drive roll, and the roll 21 is a driven roll.

Between the outlet of the casing 3 of the screw feeder 1 and the twin-screw compression molding machine 2, a seal casing 6 for preventing leakage of powder is provided. The seal casing 6 includes a pair of side seals 8 and a pair of seal members 7 connecting upper and lower edges of the pair of side seals 8. This seal casing 6 is fixed to the casing 3. The sealing member 7 is a roll 2
1, 21 'may be slid, but when not slid,
In order to reduce powder leakage from here, it is preferable to make the gap between the sealing member 7 and the rolls 21 and 21 'as narrow as possible. Further, the seal member 7 may be a separate member from the casing 3, but the seal member 7 may be configured by extending a part of the casing 3.

The rolls 21 of the pair of side seals 8,
The end on the 21 'side is the roll 2 of the biaxial roll compression molding machine 2.
1, 21 'are in sliding contact with both side surfaces, respectively. The ends of the side seal 8 on the rolls 21 and 21 'side are pressed against the rolls 21 and 21' by pressing means (not shown) such as bolts, so that the side seal 8 slides on the rolls 21 and 21 '. Can be maintained (see FIGS. 5 and 6 of Example 2 described later).

This powder molding machine has the above configuration. Next, the operation of the powder molding machine will be described.
As shown in FIG. 1, the casing 3 of the screw feeder 1
Sent inside. The screw 4 is rotated about an axis by a motor 14, and the rotation causes the powder to move along the screw 4 toward the outlet of the casing 3. During this movement, the inside of the degassing chamber 25 is suctioned by a vacuum pump (not shown), so that the porosity of the powder is reduced by the degassing, and the bulk specific gravity is increased by forced feeding.

Since the screw feeder 1 is of a self-cleaning type, as shown in FIG. 2, the tip of one screw paddle 4b is close to the surface of the other screw paddle 4b and close to the inner surface of the casing 3, so that the powder In order to scrape off the powder, the powder having increased bulk specific gravity is smoothly and uniformly fed into the seal casing 6 with uniform properties, and is subjected to uniform compression molding by the rolls 21 and 21 ′. After being sent out, it is pulverized into granules by a granulator (granulator) in a later step. At the time of sending out this product, a space a between the rolls 21 and 21 ′ and the seal casing 6 a
The powder that has leaked from the outlet hood 24 also enters the outlet hood 24.

FIGS. 5 and 6 show another embodiment. In the second embodiment, the deaeration function is added to the seal casing 6 in the first embodiment. That is, as shown in FIG. 6, the side seal 8 includes a side seal plate 9, a filter 10, a sliding member 11, and a mounting member 15, and each side-seal plate 9 is provided with a deaeration chamber 12. I have. The deaeration chamber 12 is a part of the seal casing 6 located between the tip of the screw 4 on the outlet side of the casing 3 and the rolls 21 and 21 ′, and each of the pair of side seals 8 constituting the seal casing 6 A concave portion is formed on each inner surface of the side seal plate 9. Degassing chamber 1
2 is provided with a deaeration hole 13 and is connected to an external vacuum pump (not shown).

A filter 10 is attached to the deaeration chamber 12 via an attachment member 15 so as to cover the opening.
The filter 10 is relatively coarse, and is made of, for example, a sintered metal and is attached to the attachment member 15 by welding (the filter 28 is a similar material). The sliding member 11 is provided with a side seal 8 to prevent powder leakage.
And the rolls 21 and 21 ′ are provided at portions where they are in sliding contact with each other.
The filter 10 is arranged in a close state with a slight gap from the rolls 21 and 21 ′.
1, 21 'can efficiently suck air with increased pressure generated when the powder is compressed.

In the second embodiment, similarly to the first embodiment, the screw feeder 1 is evacuated and forcedly fed, so that the granular material having a large specific gravity is fed into the seal casing 6. In the seal casing 6, a side seal 8 forming a part thereof is provided with a deaeration chamber 12, so that air in the powder is sucked by a vacuum pump.

Then, the powder is supplied to two rolls 21 and 2
1 'is sent between the two peripheral surfaces, where it is compressed. When the powder is compressed, the air pressure also increases,
Since the filter 10 is provided near 21 ′,
This air is also efficiently sucked by the vacuum pump, and the pressure rise is suppressed.

As described above, both the air whose pressure is increased by the rotation of the screw feeder 1 and the air whose pressure is increased by the compression of the rolls 21 and 21 ′ are sucked to suppress the pressure increase in the seal casing 6. Since the pressure difference between the inside of the seal casing 6 and the atmosphere is reduced, the amount of air leaking from the gap a between the side seal 8 and the rolls 21 and 21 'is reduced, and the amount of powder leaking with the air is also reduced. can do.

In the second embodiment, the deaeration chamber 12 with the filter 10 may be provided on both or one of the upper and lower surfaces (seal member 7) of the seal casing 6. Further, the deaeration chamber 25 of the screw feeder 1 may be provided on the entire length of the feeder, or may be provided on the entire outer periphery of the casing 3. These are appropriately determined in consideration of the deaeration rate, manufacturability, and the like. In both Embodiments 1 and 2, the number of screws 4 is not limited to two, but may be three or more.

[0028]

[Experimental example] When the sodium bicarbonate powder was molded from the non-degassed examples (Example 1), Example 2 and Example 1 (Comparative Example 1), the molded product and the powder sent out from both rolls 21 and 21 'were used. Body and rolls 21, 21 'and seal casing 6
Powdering ratio (% by weight), which is the ratio of the amount of powder in the total amount of powder leaked from the space (the total amount taken out of the outlet hood 24).
Was 20.4% in Example 1, 14.5% in Example 2, and 37.8% in Comparative Example 1. The air pressure in the seal casing 6 was about 2 kgf / cm ² in Comparative Example 1, and about 1.5 kgf / cm ² in Example 2.
It was estimated to be about ² .

From this powder ratio, it can be understood that powder leakage at the compression roll portion can be effectively reduced by degassing. In addition, in the uniformity of the properties, shape, size, etc. of the molded product, both examples are extremely superior to Comparative Example 1. From this, it is understood that the effectiveness of the self-cleaning type deaerated screw feeder 1 is understood. it can.

Further, in Example 1 and Comparative Example 1,
As a result of compression molding of the resin powder, Example 1 exhibited a processing capacity nearly 1.8 times that of Comparative Example 1, and the filter 28 in Example 1 was clogged causing a reduction in processing capacity even after 30 hours of operation. Did not occur.

[0031]

According to the present invention, since the screw feeder with the deaeration function is a self-cleaning type having a plurality of shafts, powder having a large specific gravity can be smoothly and uniformly fed between the compression rolls. For this reason, a molded article having uniform properties can be obtained.

Also, a part of the casing of the screw feeder is expanded, its opening is closed by a lid, and the filter can be removed by opening and closing the lid.
Maintenance can also be easily performed.

[Brief description of the drawings]

FIG. 1 is a front view showing an embodiment of a powder molding machine according to the present invention.

FIG. 2 is a cut-away side view of the screw feeder of FIG. 1;

3A and 3B show a screw of the embodiment, wherein FIG. 3A is a perspective view of a screw paddle, FIG. 3B is a perspective view of a kneading paddle,
(C) is a perspective view of another example of the kneading paddle.

FIG. 4 is a cut front view of the screw of the embodiment.

FIG. 5 is a front view of a main part of another embodiment.

FIG. 6 is a fragmentary plan view of the same embodiment.

FIG. 7 is a partially enlarged sectional view showing an example of a conventional powder molding machine.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Screw feeder 2 Biaxial roll compression molding machine 3 Casing 4 Screw 4a Screw shaft 4b Screw paddle 4c, 4c 'Kneading paddle 5 Hopper 6 Seal casing 7 Seal member 8 Side seal 9 Side seal plate 10 Filter 11 Sliding member 12 Roll side Deaeration chamber 13 Deaeration hole 14 Motor 15 Joining member 21, 21 'Roll 22, 22' Roll shaft 23 Hydraulic cylinder 25 Screw feeder side deaeration chamber 26 Deaeration chamber 27 Cover 28 Filter 31 Screw 32 Casing 33 Ventilation plate 34 Deaeration cylinder 35 Vacuum pump 36 Motor 37 Roller

──────────────────────────────────────────────────の Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B30B 11/18 B01J 2/22 B30B 11/24

Claims (2)

(57) [Claims] 1. A twin-screw roll compression molding machine 2 is installed in front of an outlet of a casing 3 of a screw feeder 1, and the powder to be forcibly fed by the screw feeder 1 to the compression molding machine 2 for compression molding. In the body forming machine, the screw feeder 1 is a self-cleaning type in which a plurality of screws 4 are arranged in parallel, and a powder feeding hopper 5 of a casing 3 of the screw feeder 1.
By bulging the side lower portion to form a degassing chamber 25, and characterized in that between the degassing chamber 25 and the screw 4 which is interposed a filter 28, and a screw feeder 1 to be deaerated Powder molding machine. 2. An outlet of the casing 3 of the screw feeder 1.
The twin-screw roll compression molding machine 2 is installed in front of the
The powder is forcibly forced to the compression molding machine 2 by the ruby feeder 1.
In a powder molding machine for feeding and compression molding, a plurality of screws 4 are connected to the screw feeder 1 in parallel.
The self-cleaning type
A part of the casing 3 of the feeder 1 is expanded to form a degassing chamber 2.
5 between the deaeration chamber 25 and the screw 4.
The screw feeder 1 is evacuated by interposing the heater 28
And manner, and the bulging portion the outer surface of the degassing chamber 25 as an opening, the opening is closed by a lid 27, before Symbol filter 28, bis casing 3 together may be inserted from the opening to the deaerating chamber 25 powder molding machine characterized that it is possible to stop.