JP2007083594A - Resin pellet drying device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin pellet drying device which keeps the inside of a heating-drying means under a specified pressure-reduced state by surely closing the opening section by a simple structure, and reduces costs of the device itself by the simple structure. <P>SOLUTION: A flexible opening/closing plate, and an opening/closing means having an opening/closing operation member are respectively provided. In this case, the flexible opening/closing plate has an opening section having approximately the same size as a transferring passage and a shielding section which shields the passage on the upstream side in the transferring direction of resin pellets in a feeding hopper and a discharging hopper, and is movably supported in the horizontal direction under an approximately air-tight state. The opening/closing operation member selectively locates the opening section and the shielding section on the transferring passage by moving the opening/closing plate in the horizontal direction. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a resin pellet drying apparatus that dehumidifies resin pellets supplied to a raw material supply unit of a molding machine in advance to make them dry.

  In some cases, resin pellets, which are molding raw materials for molded articles, have moisture attached to them during transportation or the like, and water penetrates into the interior to form bound water. When moisture adheres as described above, or resin pellets in a bound water state are used as they are as raw materials for a molding machine, the moisture in the synthetic resin melted in the mold is vaporized to the outside of the mold. At that time, streaks due to water vapor are formed on the surface of the molded product, resulting in poor appearance, or the resin composition is denatured by residual moisture and the predetermined resin characteristics cannot be maintained after molding This is a cause of molding defects. For this reason, when supplying resin pellets to a molding machine, it is necessary to perform a drying process so as to dehumidify the moisture of the resin pellets in advance.

As a conventional resin pellet drying apparatus for drying resin pellets, the one shown in Patent Document 1 is known. That is, the dehumidifying and drying apparatus for resin pellets described in Patent Document 1 heats the resin pellets supplied to the molding machine under reduced pressure by exhausting the air in the drying means in advance and introducing a required amount of air. Dehumidified and dried.

In the dehumidifying and drying apparatus of Patent Document 1, when closing the lower opening of the drying means, the resin pellets in the middle of discharging cannot be completely closed and the interior of the drying means is required to be depressurized. There is a risk of a situation where it cannot be kept in a state. In order to prevent this, the opening / closing means has a double structure of a partition operation plate that stops the flow from the main body of the drying means to the storage tank and a middle plate that completely closes the valve.

However, when the opening / closing means of the dehumidifying / drying apparatus has a double structure as described above, there is a problem that the structure is complicated and the apparatus itself is expensive.
Japanese Patent No. 3354912

The problem to be solved is that in order to maintain the inside of the drying means in a required reduced pressure state, the opening / closing means needs to have a double structure. As a result, the structure becomes complicated and the cost of the apparatus itself increases. It is in.

  The present invention has an opening having a size substantially matching the transfer passage and a shielding portion for shielding the passage at the top in the transfer direction of the resin pellets in the supply hopper and the discharge hopper, and is movable in an airtight state in the horizontal direction. An opening / closing means having a flexible opening / closing plate supported and an opening / closing operation member for moving the opening / closing plate in a horizontal direction to selectively position the opening and the shielding portion in the transfer passage is provided. It is said.

According to the present invention, the opening can be reliably closed with a simple structure, and the inside of the heating and drying means can be maintained in a required reduced pressure state. The cost of the device itself can be reduced with a simple structure.

  The best mode of the present invention is to open and close the upper passage in the transfer direction of the resin pellets in the supply hopper and the discharge hopper with a flexible opening / closing plate.

The present invention will be described below with reference to the drawings showing examples.
1 to 3, a resin pellet drying apparatus 1 heats resin pellets 9 as resin raw materials supplied to a raw material supply unit (not shown) of a molding machine (not shown) to dry them to a desired moisture content. In the apparatus, the main body frame 2 is provided with a supply hopper 3, a heating cylinder 5, and a discharge hopper 7.

The supply hopper unit 3 has an upper connection port 3a to which a supply pipe 11 for conveying undried resin pellets 9 to the resin pellet drying apparatus 1 is connected to the upper part, and a lower connection connected to a heating cylinder part 5 to be described later. The upper opening / closing means 13 is provided in the upper connection port portion 3a in a hopper shape having a mouth portion 3b. The upper opening / closing means 13 has an opening / closing plate 13a supported so as to be slidable in a horizontal direction through a minute gap provided between the upper end opening of the upper connection port 3a and the pipe connection portion 11a to which the supply pipe 11 is connected. An opening / closing operation member 13b such as an air cylinder having a base end portion fixed to an attachment stay 11b attached to the pipe connection portion 11a and an operation shaft fixed to the opening / closing plate 13a.

The opening / closing plate 13a is a metal plate such as stainless steel, and has a thickness that can be easily elastically deformed under reduced pressure, which will be described later, and can be tightly sealed to the upper connection port 3a. An opening 13c having a size substantially coincident with the opening of the pipe connection portion 11a is formed on one side in the horizontal direction of the opening / closing plate 13a, and the opening for shielding the upper connection port portion 3a is shielded on the other side. Parts are provided.

  A heating cylinder portion 5 is connected to the lower portion of the supply hopper portion 3. The heating cylinder 5 includes an upper heating cylinder 5a having an axis in the horizontal direction and a lower heating cylinder 5b which is folded back at the right end of the upper heating cylinder 5a shown in the figure and connected in two stages. The upper heating cylinder 5a and the lower heating cylinder 5b are made of a metal material having a high thermal conductivity, such as stainless steel or an aluminum alloy. The upper heating cylinder 5a and the lower heating cylinder 5b are horizontally arranged in the upper heating cylinder 5a and the lower heating cylinder 5b. Transfer screws 15 and 17 each having an axis are arranged, and the shaft portions of these transfer screws 15 and 17 are detachable from the shaft end portions of the upper heating cylinder 5a and the lower heating cylinder 5b, and are airtight. The bearing members 5c and 5d to be fixed are rotatably supported.

The transfer screws 15 and 17 are rotated in a required transfer direction in accordance with driving of the electric motors 19 and 21 connected to the respective shaft portions, and transfer the resin pellets 9 introduced into the interior at a required speed. The shafts of the transfer screws 15 and 17 have a hollow structure, and an internal heating member (not shown) such as a sheathed heater is mounted in the hollow part. This internal heating member heats the resin pellets 9 transferred via the screw blades to a required temperature to vaporize the adhering water and the internal bound water. Further, an external heating member (not shown) such as a planar heater is attached to the outer surface of the upper and lower heating cylinders 5a and 5b, and the upper and lower heating cylinders 5a and 5b are mounted together with the internal heating member. The resin pellets 9 heated to a required temperature and transferred are heated to a required temperature to vaporize the adhering water and the bound water inside.

Note that reference numeral 30 in the figure denotes a heat insulating material attached to the outer surfaces of the upper and lower heating cylinders 5a and 5b to which the external heating member is attached.

An air supply nozzle 29 constituting an air supply means is mounted on the upper side (left side in the drawing) of the upper heating cylinder 5a in the transfer direction, and an air supply pipe 31 connected to the air supply nozzle 29 is an air supply device (FIG. (Not shown). The air supply device supplies dehumidified and dried air to the inside of the upper heating cylinder 5a in a required supply amount. The upper heating cylinder 5a and the lower heating cylinder 5b located on the lower side in the transfer direction from the air supply nozzle 29 are provided with a plurality of exhaust nozzles 33 constituting exhaust means at a predetermined interval toward the lower side in the transfer direction. Are installed separately. An exhaust pipe 35 connected to an exhaust device (not shown) is connected to each exhaust nozzle 33, and the air in the upper heating cylinder 5a and the lower heating cylinder 5b is exhausted to form a required reduced pressure state. To do.

The air supplied from the air supply nozzle 29 into the upper heating cylinder 5a is preferably dehumidified air, but may be undehumidified air or heated air.

A buffer hopper 37 is connected to the lower left end of the lower heating cylinder 5b located in the lower stage, and a discharge hopper 39 is connected to the lower portion of the buffer hopper 37 via a lower opening / closing means 41. A connecting portion 39a provided on the discharge side of the discharge hopper 39 is connected to a raw material supply pipe 43 connected to a raw material supply portion (none of which is shown) of the resin molding machine. Since the lower opening / closing means 41 has the same structure as the upper opening / closing means 13, the opening / closing plate is denoted by reference numeral 41a, the opening / closing operation member is denoted by reference numeral 41b, and the opening is denoted by reference numeral 41c.

In addition, the size of the opening part in the connection part of the supply hopper part 3 and the upper heating cylinder 5a, the connection part of the upper heating cylinder 5a and the lower heating cylinder 5b, and the connection part of the lower heating cylinder 5b and the discharge hopper 39 is as follows. In order to achieve consistency between the supply amount (discharge amount) of the resin pellets 9 and the transfer amount of the resin pellets 9 in the upper and lower heating cylinders 5a and 5b, the inner diameters of the upper and lower heating cylinders 5a and 5b are approximately equal to each other. It is desirable to do it.

An air supply unit of one air blow device 45 is connected to the pipe connection portion 11a, and an air discharge portion of the air blow device 45 is connected to the discharge portion 39a of the discharge hopper 39, respectively. Then, air supply and exhaust by the air blow device 45 are switched, and the resin pellet 9 is sucked into the supply pipe 11 by the air supply action and is pumped into the supply hopper 3, and from the discharge hopper 39 by the exhaust from the air exhaust. The resin pellet 9 is pumped to the raw material supply part of the resin molding machine.

Next, the heat drying action of the resin pellet 9 by the resin pellet drying apparatus 1 will be described.
First, the outline of the reduced pressure drying operation by the resin pellet drying apparatus 1 will be described. The resin pellet 9 in the supply hopper 3 is in the upper heating cylinder of the heating cylinder 5 with the upper opening / closing means 13 and the lower opening / closing means 41 closed. When the transfer screw 15 is rotated while flowing into the body 5a, the resin pellets 9 are transferred to the right side of the figure at a required speed as the transfer screw 15 rotates, and then the lower lower heating cylinder 5b. Then, it is transferred to the left side of the drawing at a required speed as the transfer screw 17 rotates.

And at the time of transfer of the resin pellet 9 in the upper and lower heating cylinders 5a and 5b, the resin pellet 9 is heated to a required temperature at which the resin pellet 9 does not melt by heat from the internal heating member and the external heating member, Moisture adhering to the outside of the resin pellet 9 and internal bound water are steamed. In particular, in the bound water inside the resin pellet 9, the resin pellet 9 is dehumidified and dried by heating it to the required temperature to vaporize it and leak it to the outside.

At the time of this heating, as shown in FIG. 4, it is lower than the atmospheric pressure by exhausting from each exhaust nozzle 33 while flowing a required amount of air from the supply nozzle 29 into the upper and lower heating cylinders 5a and 5b. An air flow from the supply nozzle 29 to each exhaust nozzle 33 is formed in a reduced pressure state, and water vapor generated by the heating is discharged out of the upper and lower heating cylinders 5a and 5b by the air flow described above. . In this way, the inside of the upper and lower heating cylinders 5a and 5b is reduced in pressure to lower the boiling point of water and to make it easier for the bound water inside the resin pellet 9 to leak out and to be generated by heating the resin pellet 9. The steam is forced to be discharged to the outside by the air flow from the supply nozzle 29 to each exhaust nozzle 33 to prevent the inside of the upper and lower heating cylinders 5a and 5b from being supersaturated with the resin pellets. The heat drying of 9 is made efficient.

Resin pellets 9 obtained by heating and drying the moisture adhering to the outer surface and the inner bound water by the above action are introduced and stored in the buffer hopper 37 along with the rotation of the transfer screw 17 in the lower heating cylinder 5b. When almost all the resin pellets 9 in the upper and lower heating cylinders 5a and 5b are introduced and stored in the buffer hopper 37, the lower opening / closing means 41 is opened to discharge the dried resin pellets 9 to the discharge hopper 39. After falling and storing in its own weight, it is supplied by being fed to the raw material supply section of the resin molding machine via the raw material supply pipe 43.

Next, the operation of the upper opening / closing means 13 and the lower opening / closing means 41 will be described. When the resin pellet 9 is supplied into the supply hopper 3, the opening / closing operation member 13b is operated to open the opening / closing plate as shown in FIG. 13a is moved in the horizontal direction and the inside of the supply pipe 11 is supplied with the opening 13c aligned with the opening of the pipe connecting portion 11a, whereby the resin pellet 9 is sucked and introduced into the supply hopper 3. . Then, after the air supply in the supply pipe 11 is stopped by a signal from a sensor (not shown) provided in the supply hopper unit 3, the open / close operation member 13b is moved backward to return the open / close plate 13a to the horizontal direction and shield it. The upper opening part of the supply hopper part 3 is closed by positioning the part at the pipe connection part 11a.

The same applies to the lower opening / closing means 41. When the resin pellets 9 in the buffer hopper 37 are allowed to flow into the discharge hopper 39, the opening / closing operation member 41b is operated to move the opening / closing plate 41a in the horizontal direction. By causing the portion 41 c to coincide with the lower opening of the buffer hopper 37, the resin pellets 9 in the buffer hopper 37 are dropped into the discharge hopper 39 and flowed in. Then, the opening / closing operation member 41b is moved backward by a signal from a sensor (not shown) provided in the discharge hopper 39 to return to the horizontal direction of the opening / closing plate 41a, and the shielding portion is positioned at the lower opening of the buffer hopper 37. Thus, the lower opening of the buffer hopper 37 and the upper opening of the discharge hopper 39 are closed.

During the above operation, since the upper opening / closing means 13 is provided above the supply hopper 3 and the lower opening / closing means 41 is provided above the discharge hopper 39, the supply hopper 3 flows into the supply hopper 3 and the discharge hopper 39. The resin pellet 9 to be dropped at least by its own weight prevents the opening and closing plates 13a and 41a from being bitten by the opening portions 13c and 41c, and the upper opening portions of the supply hopper portion 3 and the discharge hopper 39. Can be securely closed.

In addition, when the resin pellets 9 are heated and dried in the upper and lower heating cylinders 5a and 5b, a plurality of exhaust gases are supplied with air flowing from the air supply pipe 31 in the upper and lower heating cylinders 5a and 5b. By exhausting from the nozzle 33, a reduced pressure state lower than the atmospheric pressure is maintained. Under such a reduced pressure state, the opening and closing plates 13a and 41a themselves have a certain degree of flexibility, so that the shielding portions of the opening and closing plates 13a and 41a are caused by the negative pressure under the reduced pressure as shown in FIG. The upper and lower heating cylinders 5a and 5b are easily elastically deformed and brought into close contact with the peripheral edges of the upper opening portions of the supply hopper portion 3 and the discharge hopper 39 to maintain the airtight state. Thereby, when the resin pellet 9 is heated and dried, the heated and dried state of the resin pellet 9 can be made almost constant by keeping the inside of the upper and lower heating cylinders 5a and 5b in a constant reduced pressure state.

In this embodiment, the upper opening / closing means 13 and the lower opening / closing means 41 are provided above the supply hopper portion 3 and the discharge hopper 39, respectively, and discharged from the supplied resin pellets 9 and the upper and lower heating cylinders 5a and 5b. When closing the upper openings by reducing the amount of resin pellets 9 adhering to the open / close plates 13a / 41a as much as possible, the resin pellets 9 are prevented from being bitten by the open / close plates 13a / 41a and securely closed. Can be made.

Further, when the inside of the upper and lower heating cylinders 5a and 5b is in a reduced pressure state at the time of closing, the opening and closing plates 13a and 41a are easily elastically deformed by the negative pressure, and the upper portions of the supply hopper 3 and the discharge hopper 39 The dry state of the resin pellets 9 can be made constant by maintaining the reduced pressure in the upper and lower heating cylinders 5a and 5b in close contact with the periphery of the opening.

The present invention can be modified as follows.
1. In the above description, the heating cylinder portion 5 is configured by the upper and lower heating cylinders 5a and 5b having a two-stage configuration. However, depending on the amount of resin pellets 9 to be heated and dried, the time required for drying, etc., or It is good also as three steps or more.

2. In the above description, the air supply pipe 31 is provided on the upper side of the upper heating cylinder 5a in the transfer direction so that air flows into the upper and lower heating cylinders 5a and 5b. An air supply nozzle may be provided to allow air to flow into the supply hopper 3 and the upper and lower heating cylinders 5a and 5b.

3. In the above description, a plurality of exhaust nozzles 33 are attached to the upper and lower heating cylinders 5a and 5b located on the lower side in the transfer direction from the air supply nozzle 29 to form an air flow with a predetermined interval. The exhaust nozzle 33 may be attached to the lower ends of the upper and lower heating cylinders 5a and 5b in the transfer direction to exhaust the air in the upper and lower heating cylinders 5a and 5b.

4). In the above description, the resin pellet drying apparatus 1 is provided separately from the molding machine, and the dried resin pellet resin pellet 9 is supplied by being pumped to the raw material supply unit of the molding machine. The resin pellet drying device may be directly attached to the raw material supply unit of the molding machine, and the dried resin pellets may be directly supplied to the molding machine.

It is a front view which shows the whole resin pellet drying apparatus. It is a fragmentary sectional view which shows the structure of a resin pellet drying apparatus. It is a partial center longitudinal cross-sectional view of a supply hopper part. It is explanatory drawing which shows the flow state of the air in a heating cylinder. It is explanatory drawing which shows the open state of an opening / closing means. It is explanatory drawing which shows the contact | adherence state at the time of closure.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Resin pellet drying apparatus 3 Supply hopper part 5 Heating cylinder part 5a Upper heating cylinder body 5b Lower heating cylinder body 7 Discharge hopper part 9 Resin pellet 13 Upper opening / closing means 13a Opening / closing plate 13b Opening / closing operation member 13c Opening parts 15 and 17 Transfer screw 29 Air supply nozzle 33 constituting air supply means Exhaust nozzle constituting exhaust means

Claims (3)

At least one heating cylinder that transfers the resin pellets charged in the supply hopper in the horizontal direction as the feed screw rotates, and a resin pellet that is provided in the transfer direction of the heating cylinder and is dried by heating. A supply hopper that is charged, a heating member that heats the resin pellets that are transported through the heating cylinder to a non-melted required temperature, and an air supply means that supplies air into at least the upper side in the transfer direction of the heating cylinder, Exhaust means for discharging the air inside the heated cylinder on the lower side of the air supply means, and heat dried resin pellets discharged from the heated cylinder inside are provided in the lower side in the transfer direction of the heated cylinder. In a resin pellet drying apparatus equipped with a discharge hopper, an opening having a size substantially corresponding to the transfer passage is well positioned in the transfer direction of the resin pellets in the supply hopper and the discharge hopper. A flexible opening / closing plate supported to be movable in a substantially airtight state in the horizontal direction, and moving the opening / closing plate in the horizontal direction to transfer the opening and the shielding portion. Resin pellet drying apparatus provided with opening / closing means each having an opening / closing operation member to be selectively positioned in a passage. The resin hopper drying apparatus which provided the air supply means in the supply hopper of Claim 1. 2. The resin pellet drying apparatus according to claim 1, wherein the opening and closing plate is a metal plate having a plate thickness capable of being in close contact with a passage on the upper side in the transfer direction of the supply hopper and the discharge hopper.

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