JPH0839566A - Resin feeding method and resin feeding device bed therewith - Google Patents

Abstract

PURPOSE:To remove a powder-like resin, which is the cause of foreign matter and a defect, when a plastic molding resin is fed from a tank through the hopper of a resin feeding device to a molding device. CONSTITUTION:After a resin is fed from a tank to a hopper 2, the hopper 2 is turned into a closed system and communicated with a dust collector so as to blow the interior of the hopper 2 with dried and antistaticized air for a predetermined period of time in order to recover resin powder separated during blowing with the dust collector. After blowing the closed system of the hopper 2 is released so as to feed the resin to a molding device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin supply method for supplying a plastic molding resin to a molding apparatus and a resin supply apparatus used for the same.

[0002]

2. Description of the Related Art A resin supplying device is a device having a function of automatically supplying a resin stored in a tank to a molding device when necessary, and is generally widely used in a factory that molds plastics. This is the device used. In particular, in the case of a hygroscopic resin, for example, a polycarbonate resin, an acrylic resin, etc., in addition to the above functions, by circulating hot air of a predetermined dry temperature in the tank, a problem occurs during heating and melting in the molding process. There is also used a resin supply device that also has a function of reducing the amount of water in the resin to the extent that it disappears and automatically supplying the resin dried to such a state to the molding device as needed.

FIG. 1 shows the basic structure of the above-mentioned resin supply device. 1 is a tank for storing the resin before supply, 2 is a tank 1
A hopper for temporarily storing the resin inside the molding apparatus M, 3 is a suction device for sucking and introducing the resin in the tank 1 into the hopper 2, and 4 is a resin supply from the tank 1 to the hopper 2. A sensor unit 5 for determining necessity is a supply damper provided between the hopper 2 and the sensor unit 4,
6 is a supply pipe, and 7 is a suction pipe. Further, the resin supply device is provided with various valves at predetermined locations, and the entire operation of resin supply is controlled by a control unit (not shown). The tank 1, the hopper 2, and the supply pipe 5 are usually made of sanitary stainless steel in order to prevent contamination due to frictional wear with the resin, and the suction pipe 6 has a structure capable of withstanding negative pressure. The flexible hose that has it is generally used. Further, the sensor portion 4 is made of a glass tube so that the level of the resin can be easily visually recognized, and a method of detecting the level by a capacitance type sensor is generally adopted.

The control of this resin supply device is performed as follows. That is, when the resin inside the glass tube of the sensor section 4 provided at the lower part of the hopper 2 becomes below a predetermined level,
The sensor of the sensor unit 4 detects this, activates the suction device 3 to reduce the pressure in the hopper 2, and the resin in the tank 1 is introduced into the hopper 2 by the negative pressure. Normally, this operation is continued for a predetermined time by a timer so that the hopper 2
A predetermined amount of resin is supplied inside. Then, after the resin is supplied, the supply valve at the lower part of the sensor unit 4 is opened, and when the molding apparatus M consumes the resin in the hopper 2 and the resin in the glass tube becomes below a predetermined level again, the above operation is repeated. Do it.

[0005]

In the resin supply device described in the prior art, pellet-like resin is put in the tank. And, if necessary, this dried pellet-shaped resin is supplied to the hopper.
When supplied, the powdery resin is generated as scraps from the pellets due to contact between the pellets and the metal pipe or contact between the pellets. Since this powdery resin has an extremely small size as compared with normal pellets, the melting rate in the heating cylinder of the molding device is different, and the residence time becomes longer, so that it deteriorates and becomes foreign matter or There was a problem of causing defects. Also, the sensor part may become dirty by sticking to the glass tube, entering into the gap, sticking to the resin supply part of the molding device, etc. Is supplied to
There was also a problem of causing foreign matter and defects.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a resin supply method capable of removing powdery resin which causes foreign matters and defects, and a resin supply used therefor. To provide a device.

[0007]

[Means for Solving the Problems] As a result of various studies to solve the above problems, as a countermeasure, there are two fundamental measures: prevention of generation of powder and active removal of generated powder. It was However, the former was judged to be difficult because the generation of powder is unavoidable due to the structure of the device. Therefore, the latter method is adopted, and the powder is positively removed at the hopper where the resin is finally supplied. That is, it is because the powder is basically generated until it is supplied to the hopper, and it is determined that if the powder is removed at the hopper portion, only the hopper portion can handle it.

The present invention has been made on the basis of the results of such studies, and the resin supply method according to the present invention, when the plastic molding resin is supplied from the tank to the molding device through the hopper of the resin supply device, After supplying the resin from the tank to the hopper, the hopper is closed and communicated with the dust collector, and the resin powder released at that time is collected by the dust collector while blowing in the hopper for a predetermined time with air that has been dried and discharged. Then release the closed system of the hopper,
The resin supply device is characterized by supplying the resin to the molding device, and the resin supply device used in this method is a resin supply device equipped with a hopper for supplying the plastic molding resin to the molding device. Means for blowing the inside of the hopper, and a dust collector communicating with the inside of the hopper when the hopper is closed.

[0009]

The series of steps in the above-mentioned resin supply method of the present invention will be described in detail below together with the operation.

The resin is supplied from the tank to the hopper.
After closing the supply damper directly below the hopper to disconnect the sensor glass tube from the hopper and opening the supply pipe to enable resin supply to the hopper, operate the suction device for a certain period of time. Supply resin into the hopper. That is, the inside of the hopper and the supply pipe is depressurized by the operation of the suction device, and the resin is supplied from the tank into the hopper through the supply pipe.

The hopper is closed and communicates with the dust collector. Close the resin supply pipe to disconnect the hopper from the tank, and switch the suction pipe to the dust collector side. As a result, the hopper becomes an independent system from the resin supply / conveyance system, and it becomes possible to remove the powdery resin present in the independent system.

While the air inside the hopper is blown for a predetermined time with the dried and static-removed air, the powder released at that time is collected by a dust collector. First, the reason for drying the air is
One is to prevent the inside of the hopper closed system from being contaminated with water, and the other is to prevent unnecessary moisture from being given to the resin inside the hopper closed system. Specifically, it is desirable to pass the air that has passed through the air dryer through several stages of oil mist traps and air filters. Further, the reason why the air is neutralized is to prevent as much as possible the state in which powders that are easily charged are attached to each other or to the pellets. Specifically, a method of ionizing air with an ionizer by electric discharge is a method that can be easily realized and is desirable. Since it is necessary to blow the air that has been subjected to such treatment evenly into the hopper and float up the powder mixed in the pellets, it is necessary to provide a blow-out port in the hopper so that it becomes a ring shape, or on the same circumference. It is desirable to provide three or more outlets. The dust collector is operated in order to remove the floated powder, but its air volume needs to be an amount corresponding to the above air supply capacity, and a desirable air volume is 0.1 to 10 m ³ / min. Then, this operation is continuously performed until the resin is consumed by the molding device and the sensor detects that the resin in the glass tube in the sensor unit is below a predetermined level. By doing so, the dust can be collected for as long as possible.

The closed system of the hopper is released, and the resin is supplied to the molding device. Open the supply damper just below the hopper and connect the glass tube of the sensor to the hopper. By this operation, the resin in the hopper can be supplied to the molding apparatus through the glass tube. Then, after a lapse of a predetermined time, the operation returns to the above-mentioned operation, and the series of operations are repeated, whereby the powdery resin is efficiently removed.

[0014]

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

FIG. 2 is a schematic configuration diagram showing a resin supply device as one embodiment of the present invention. The device of this embodiment is an existing resin supply device (CD100H200-2S25C,
It was created by improving Kawata Co., Ltd.

As shown in the figure, an electromagnetic on-off valve 11 is attached to the resin supply port 2a of the hopper 2, and a resin supply pipe 6 is attached to one of the electromagnetic on-off valves 11. In addition, the electromagnetic three-way valve 1 is attached to the suction port 2b of the hopper 2.
2 is attached, a normal suction pipe 7 is connected to one of the electromagnetic three-way valves 12, and a dust collector pipe 13 is connected to the other, and the dust collector pipe 13 is connected to a dust collector (not shown). Has been done. Further, the pedestal 14 of the hopper 2
As shown in FIG. 3, a ring-shaped air blowout hole 14b for blowing out air toward the inside of the wall surface 14a is provided in the. That is, the air introduced from the air inlet 14c is guided to the ring-shaped portion 14e through the passage 14d,
It is configured to blow out from the blow-out hole 14b in the upper part. Then, the air that has passed through the air dryer, the oil mist filter, the air filter, and the neutralization processing device is blown into the air inlet 14c.

Polycarbonate resin pellets are placed in a tank for storing the molding resin, sufficiently dried in the tank, and then the resin is supplied from the tank to the molding apparatus through the hopper of the resin supply apparatus having the above-described structure. Injection molding was performed. The operation procedure is as follows.

First, the electromagnetic on-off valve 11 is opened and the electromagnetic three-way valve 12 is switched to the suction pipe 7 side. Then, the supply damper 5 immediately below the hopper 2 is closed and then the suction device is activated. As a result of performing suction for 20 seconds with the suction device, about 400 g of resin was supplied into the hopper 2. Immediately thereafter, the electromagnetic on-off valve 11 was closed and the electromagnetic three-way valve 12 was switched to the dust collector pipe 13 side. After the hopper 2 was closed as described above, the dust collector was operated while the dried and neutralized air was blown out from the air blowing hole 14b provided in the pedestal 14 of the hopper 2. The operation time of this dust collector is until the sensor 4b determines that the resin in the glass tube 4a of the sensor unit 4 has been consumed by the molding apparatus until the resin reaches a predetermined level, and the resin supply signal is issued. As a result, the dust collection process was performed for 2 minutes and 30 seconds.

Immediately after stopping the operation of the dust collector, the supply damper 5 is opened, and the resin thus treated is supplied to the glass tube 4a of the sensor section 4. Then, after 10 seconds have passed since the supply damper 5 was opened, the above series of operations for opening the electromagnetic opening / closing valve 11 were repeated.

As a result of repeating the above operation,
Powdery resin was collected in the dust collector. Also,
Looking at the molded product obtained by the injection molding machine, it was confirmed that the ratio of the foreign matter contamination defect, which was considered to be the cause of the powdery resin, was reduced from 15% in the case of untreatment to 2%.

The concept of powder removal adopted in the present invention can be applied to a general method and apparatus for conveying and supplying particles. In other words, it can be applied as a general-purpose method for removing powdery substances which are out of the required range and which adversely affect the subsequent steps, which are caused by the destruction of granules.

[0022]

As described above, according to the present invention,
The relatively easy modification has an advantage that contamination by powdery resin related to the molding apparatus can be prevented. Further, since the powdery resin is removed, it is possible to prevent defects in the molded product due to the powdery resin. Further, there is an effect that it is possible to prevent malfunction of the resin supply device which is caused by adhesion of powdery resin or charged resin to the glass tube of the sensor section.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a basic configuration of a conventional resin supply device together with a molding device.

FIG. 2 is a schematic configuration diagram showing a resin supply device as one resin of the present invention.

3 shows a pedestal of a hopper used in the resin supply device of FIG. 2, (a) is a top view, and (b) is a sectional view taken along line XX in (a).

[Explanation of symbols]

 1 Tank 2 Hopper 3 Suction device 4 Sensor 5 Supply damper 6 Supply pipe 7 Suction pipe 11 Electromagnetic on-off valve 12 Electromagnetic three-way valve 13 Dust collector pipe 14 Pedestal

Claims (2)

[Claims] 1. When supplying a plastic molding resin from a tank to a molding device through a hopper of a resin supply device, after the resin is supplied from the tank to the hopper, the hopper is closed to communicate with the dust collector, and drying and A resin supply characterized by discharging the resin powder released at that time with a dust collector while blowing the inside of the hopper for a predetermined time with static-free air, then releasing the closed system of the hopper and supplying the resin to the molding device. Method. 2. A resin supply device provided with a hopper for supplying a plastic molding resin to a molding device,
A resin supply device comprising: a means for closing the hopper, a means for blowing the inside of the hopper, and a dust collector communicating with the inside of the hopper when the hopper is closed.