JP2000006151A - Supply method of resin pellets to resin molding machine - Google Patents

Abstract

(57) [Problem] To provide a method of supplying a resin pellet to a resin molding machine, which can efficiently dry the resin pellet in a short time. SOLUTION: In supplying resin pellets P to an injection molding machine 100, air in a tank 120A of a heated air stirring type dryer 120 is sucked by a suction blower 66 with a control valve 128 closed, and an air transport pipe 62 is provided. The resin pellet P is pneumatically transported from the container 20 to the heated air stirring type dryer 120 by generating an air flow therein. Thereafter, the control valve 62a is closed, the control valve 128 is opened, and the suction blower 66 is operated. Thereby, the heater 12 is placed in the tank 120A of the heated air stirring type dryer 120 through the heated air supply pipe 124.
6, the heated air flows in, and the heated air causes the resin pellets P in the heated air stirring type dryer 120 to be heated.
Is agitated by air, heated and dried.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for supplying resin pellets to a resin molding machine such as an injection molding machine.
More specifically, the present invention relates to a method for supplying resin pellets to a resin molding machine, which is capable of shortening a drying time and removing resin fine powder mixed in resin pellets.

[0002]

2. Description of the Related Art At present, disks such as CDs, MDs, and VDs are widely used for recording information such as sound and images, and magneto-optical disks and hard disks are widely used for recording information in computers. Such information recording disks are required to have high quality, and mechanical characteristics such as warpage and values allowed for protrusions and holes on the substrate surface are extremely small. For example, in the case of a magnetic disk such as a hard disk, as shown in FIG. 4, the head H is lifted up from the surface by several tens of nm while rotating at several thousand rpm to write and read data. Even if a protrusion C of about 1 μm is present, a collision with the head H is caused. In FIG. 4, B indicates a resin substrate formed by injection molding described later, D indicates a foreign substance forming a projection C, and M indicates a magnetic layer.

By the way, the above-mentioned information recording disk is
Generally, it is manufactured by molding a substrate B by injection molding or the like using resin pellets as a raw material, and forming a magnetic layer (recording layer) M on the surface of the molded resin substrate B. Then, in the injection molding of the substrate B, when a resin pellet is insufficiently dried or the like, bubbles are generated on the substrate surface to form a concave defect or the like. Is provided, and the resin pellets are dried by a dryer.

Conventionally, when supplying resin pellets to an injection molding machine, a supply device as shown in FIG. 2 has been used.
As shown in the figure, the supply device connects the container 20 and the vacuum dryer 40 with a primary air conveyor 60,
Machine hopper 102 and vacuum dryer 4 of injection molding machine 100
0 is connected by a secondary air conveyor 80.

[0005] The container 20 is made of resin pellets P from above.
And a primary air conveyor 60 is connected to the lower part of the container 20 to store the resin pellets P.
The resin pellets P are transported to the vacuum dryer 40 by the primary air conveyor 60. A secondary air conveyor 80 is connected to the upper part of the machine hopper 102 of the injection molding machine 100, and the resin pellets P in the vacuum dryer 40 are pneumatically transported by the secondary air conveyor 80 and stored in the machine hopper 102. . The container 20 and the machine hopper 10
2 is well-known, and its detailed description is omitted.

[0006] As shown in FIG. 3, the vacuum dryer 40 has a primary air conveyor 60 on an upper part of a tank main body 42 and a tank main body 42.
A secondary air conveyor 80 is connected to the lower part of the container, and the resin pellets P are supplied to the tank body 42 by the primary air conveyor 60, and the dried resin pellets P are sent out by the secondary air conveyor 60. The tank body 42 is provided with a tape heater 44 on the outer circumference, the outer circumference is covered with a heat insulating material 46 provided on the tape heater 44, and the upper part is connected to a vacuum pump 48 a by a vacuum pipe 48. . Reference numeral 48b in the figure is a control valve.

The primary air conveyor 60 is formed by connecting the lower part of the container 20 and the upper part of the tank body 42 of the vacuum dryer 40 with an air transport pipe 62, and the upper part of the tank body 42 is connected with an air suction pipe 64. The air suction pipe 64 is connected to the suction blower 6.
6 is connected. The pneumatic transport pipe 62 has a branched end at the container 20 side, a branched end opened to the atmosphere via a filter 68, and a control valve 62a provided. Similarly, a control valve 64a is also provided on the air suction pipe 64.

The secondary air conveyer 80, like the primary air conveyer 60, is formed by connecting the lower part of the tank body 42 of the vacuum dryer 40 and the upper part of the machine hopper 102 by an air transport pipe 82. The air suction pipe 84 is connected to the upper part of the air suction pipe, and the air suction pipe 84 is connected to a suction blower 86.
The pneumatic transport pipe 62 branches off on the tank main body 42 side of the vacuum dryer 40, and has a branched end opened to the atmosphere via a filter 88. Reference numerals 82a and 84a in the figure are control valves.

As is well known, the primary air conveyor 60 and the secondary air conveyor 80 suck air by suction blowers 66 and 86 to generate air flows in the air transport pipes 62 and 82, and the air flows cause the resin to flow through the resin. Transport the pellets. That is, the primary air conveyor 60 sucks air in the tank body 42 of the vacuum dryer 40 by the suction blower 66 to reduce the pressure in the tank body 42, and the secondary air conveyor 80 draws air in the machine hopper 102 into the suction blower 86. To reduce the pressure inside the machine hopper 102 to generate an air flow to pneumatically transport the resin pellets.

This supply device transports the resin pellets stored in the container 20 to the vacuum dryer 40 by the primary air conveyor 60 and vacuum-drys the resin pellets. It is transported by the conveyor 80 to the machine hopper 102, that is, the injection molding machine 100. Then, the vacuum dryer 40 depressurizes the inside of the tank main body 42 to a predetermined degree of vacuum by a vacuum pump 48a, heats the tape heater 44 by energizing it, and dries the resin pellets in the tank main body 42.

[0011]

However, in the supply device described above, since the vacuum dryer 40 heats with the tape heater 44 provided on the outer wall of the tank body 42, the resin pellets in the tank body 42 A considerable temperature gradient (eg, 12 hours or more) is required until the temperature of the resin pellet at the central portion of the tank main body 42 rises to the set temperature (eg, 100 ° C.) due to a temperature gradient in which the central portion has a low temperature and the peripheral portion has a high temperature. And, furthermore,
There has been a problem that a predetermined time must be maintained at the set temperature, and a long time is required for drying. The present invention has been devised in view of the above circumstances, and an object of the present invention is to provide a method of supplying resin pellets to a resin molding machine that can efficiently dry resin pellets in a short time. And

[0012]

In order to achieve the above object, the present invention provides a method for drying a resin pellet, which is performed by blowing heated air to the resin pellet when supplying the dried resin pellet to a resin molding machine. In a heating air stirring type drying step of stirring resin pellets. Further, the present invention provides a heating air stirring type drying step before or after the drying step when supplying the resin pellets to the resin molding machine after a drying step of drying the resin pellets, In the process, heated air is blown onto the resin pellets, and the resin pellets are stirred by the heated air.

In the present invention, heated air is blown onto the resin pellets, and the resin pellets are heated by stirring the air with the heated air. Therefore, the resin pellets can be efficiently dried in a short time. Then, the resin pellets thus dried may be directly supplied to a resin molding machine, or the present invention may be carried out before or after a conventional drying step. For example, if the present invention is carried out before the conventional drying step, since pre-heated resin pellets are supplied, drying can be performed only by holding a predetermined time at the set temperature, and the resin pellets are heated to the set temperature. Time can be omitted and drying can be performed in a short time.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram schematically showing a part of a resin pellet supply device for carrying out the method of the present invention. In the present embodiment, the resin molding machine is an injection molding machine.
The same parts as those of the conventional supply device shown in FIG. 2 described above are denoted by the same reference numerals, and some of the illustrations and descriptions are omitted.

Numeral 120 denotes a heated air stirring dryer, and a tank 120 A of the heated air stirring dryer 120 is a vacuum dryer 4.
0 is provided directly above the tank body 42. The tank 120A of the heated air stirring type dryer 120 is connected to the container 20 via the primary air conveyor 60, and the lower part of the tank 120A is connected to the upper part of the tank body 42 of the vacuum dryer 40 via the gate valve 122. ing. The air transport pipe 62 of the primary air conveyor 60 is connected to the lower part of the tank 120A of the heated air stirring type dryer 120 obliquely upward,
The air suction pipe 64 is connected to the tank 12 of the heated air stirring dryer 120.
It is communicated at the top of OA.

A heated air stirring type dryer 1 for the air transport pipe 62
A control valve 62a (corresponding to a second opening / closing valve in the claims) is provided at a position closer to 20 and a hot air stirring type dryer 12
A heating air supply pipe 124 is connected to 62 points of the air transport pipe between the control valve 62 and the control valve 62a. The heated air supply pipe 124 is provided with a filter 124a at an end thereof, and the end is opened to the atmosphere through the filter 124a. The intermediate heater 126 and the control valve 128 (the first opening / closing device in the claims) (Equivalent to a valve) are interposed in series. The heater 126 includes a well-known electric heater or the like, and heats the air flowing through the heating air supply pipe 124.

In the present embodiment, the injection molding machine 10
When the resin pellets P are supplied to the container 0, first, the resin pellets P stored in the container 20 are transported to the heated air stirring type dryer 120 by the primary air conveyor 60.
That is, the primary air conveyor 60 is connected to the heated air supply pipe 1.
While the control valve 128 is closed, the suction blower 66 sucks air in the tank 120A of the heated air stirring type dryer 120 to generate an air flow in the air transport pipe 62 to remove the resin pellets P from the container 20. Heated air stirring dryer 1
Pneumatic transport to 20.

Thereafter, when a predetermined amount of the resin pellets P is transported into the tank 120A of the heated air stirring type dryer 120,
The control valve 62a of the air transport pipe 62 is closed, and the control valve 128 of the heated air supply pipe 124 is opened to operate the suction blower 66. For this reason, the heater 120 is provided in the tank 120A of the heated air stirring type dryer 120 through the heated air supply pipe 124.
6, the heated air flows in, and the heated air causes the resin pellets P in the heated air stirring type dryer 120 to be heated.
Is air-stirred, heated and dried (preliminary drying).

At the time of the preliminary drying as described above, the fine resin powder mixed in the resin pellets P is also sucked by the suction blower 66 together with air and removed. That is, while the resin pellets P are being transported, collision of the resin pellets P, and generation of fine powder due to collision of the resin pellet P with the pipe wall of the air transport pipe 62 are unavoidable. During predrying, the air is sucked together with air by the suction blower 66 and is removed from the inside of the tank 120A.

Then, when a predetermined time has elapsed after the air stirring was started in the heated air stirring type dryer 120, or when the resin pellets P (heated air stirring type dryer 120
When the temperature inside the tank 120A reaches a preset temperature, the operation of the suction blower 66 is stopped, the gate valve 122 is opened, and the resin pellets P in the heated air stirring type dryer 120 are removed by a vacuum dryer. Transfer to 40 and perform vacuum drying. That is, as described above, the vacuum dryer 40 depressurizes the inside of the tank main body 42 to a specified degree of vacuum and heats it by the tape heater 44 to dry the resin pellets P.

Here, the resin pellets P are transferred to the vacuum dryer 40 while being heated to a predetermined temperature by the heated air stirring type dryer 120, and the resin pellets P at the center of the tank body 42 also have a considerable temperature. Therefore, in the vacuum dryer 40, the time for heating the resin pellets P to the set temperature can be omitted, and the resin pellets P can be dried in a short time. That is, the vacuum dryer 40 eliminates the time required to raise the temperature of the resin pellet P at the center of the tank body 42 to a predetermined temperature.
Drying can be performed in a short time.

Thereafter, the resin pellets P dried by the vacuum dryer 40 are injected by the secondary air conveyor 80 into the injection molding machine 1.
00 is transferred to the machine hopper 102 of the injection molding machine 10
0 forms the substrate B or the like using the resin pellet P as a raw material.
Since the resin pellets P supplied to the machine hopper 102 have the resin fine powder removed by the heated air stirring type dryer 120, it is possible to prevent the substrate B from being inconvenienced by the protrusions C and the like.

It should be noted that the heated air stirring dryer 120 may be provided between the machine hopper 102 and the vacuum dryer 40, or only the heated air stirring dryer 120 may be used depending on the resin product or the molding method. The dried pellets may be directly supplied to a resin molding machine.

[0024]

As is clear from the above description, the present invention
Since the heated air is blown onto the resin pellets and the resin air is stirred by the heated air, the effect of greatly reducing the drying time of the resin pellets is obtained. In addition, stirring of the resin pellets by the heated air is performed inside the tank. At this time, if the air inside the tank is sucked,
The effect that the resin fine powder mixed in the resin pellet can be removed is also obtained.

[Brief description of the drawings]

FIG. 1 is a view schematically showing a part of a resin pellet supply device for carrying out a method of the present invention.

FIG. 2 is a schematic diagram of a resin pellet supply device using a conventional resin pellet drying device.

FIG. 3 is a schematic sectional view of a vacuum dryer of the drying apparatus.

FIG. 4 is a partially enlarged schematic cross-sectional view of a magnetic disk formed by injection molding using resin pellets.

[Explanation of symbols]

20: container, 40: vacuum dryer, 42: tank body, 44: tape heater, 48a: vacuum pump, 6
0: primary air conveyor, 62: air transport pipe, 62a
... Control valve, 64 Air suction pipe, 66 Suction blower, 68 Filter, 80 Secondary air conveyor, 1
00: injection molding machine, 102: machine hopper, 120
…… A heated air stirring type dryer, 122 …… Gate valve,
124: heated air supply pipe, 124a: filter, 1
26: heater, 128: control valve, P: resin pellet.

Claims (12)

[Claims] When drying a resin pellet and supplying it to a resin molding machine, drying of the resin is performed in a hot air stirring type drying step of blowing heated air to the resin pellet and stirring the resin pellet with the heated air. A method for supplying resin pellets to a resin molding machine. 2. A heating air stirring type drying step is provided before or after the drying step when supplying the resin pellets to a resin molding machine after a drying step of drying the resin pellets. 3. The method for supplying resin pellets to a resin molding machine according to claim 1, wherein heated air is blown onto the resin pellets, and the resin pellets are stirred by the heated air. 3. The method for supplying resin pellets to a resin molding machine according to claim 1, wherein the stirring of the resin pellets by the heated air is performed inside a tank. 4. The method for supplying resin pellets to a resin molding machine according to claim 3, wherein the stirring of the resin pellets by the heated air is performed while sucking air inside the tank. 5. The method for supplying resin pellets to a resin molding machine according to claim 4, wherein fine powder of resin is removed from the inside of the tank by suction of air inside the tank. 6. The method for supplying resin pellets to a resin molding machine according to claim 3, wherein the blowing of the heated air onto the resin pellets is performed obliquely upward from a lower portion of the tank. 7. The method for supplying resin pellets to a resin molding machine according to claim 3, wherein the suction of the air is performed from an upper part of a tank. 8. The tank, wherein resin pellets are pneumatically transported by an air transport pipe, and the heated air is supplied from a heated air supply pipe to the inside of the vessel via the air transport pipe. Item 4. A method for supplying resin pellets to an injection molding machine according to Item 3. 9. The heated air supply pipe is connected to the air transport pipe via a first opening / closing valve, and a second opening / closing is provided at the air transport pipe location upstream of a location where the heated air supply pipe is connected. A valve was provided, and pneumatic transport of the resin pellets was performed by the air transport pipe in a state where the second on-off valve was opened and the first on-off valve was closed, and the first on-off valve was opened and the second on-off valve was closed. The method for supplying resin pellets to a resin molding machine according to claim 8, wherein the supply of heated air is performed in a state. 10. The method for supplying resin pellets to a resin molding machine according to claim 2, wherein the drying step is performed by a vacuum dryer. 11. The method for supplying resin pellets to a resin molding machine according to claim 10, wherein the tank for stirring the resin pellets by the heated air is provided immediately above the tank of the vacuum dryer. 12. The method for supplying resin pellets to a resin molding machine according to claim 1, wherein said resin molding machine is an injection molding machine.