JPH0686058B2 - Microwave dryer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a microwave dryer.

(B) Prior art Japanese Patent Application No. 1-47803 discloses a microwave drying apparatus for microwave-drying a material to be dried by applying microwaves to the drying chamber. . The apparatus is provided with stirring means for stirring the material to be dried so that the material to be dried is evenly dried. Such a stirring means is connected to a transmission means which reaches the inside of the drying chamber from the outside of the drying chamber, and the stirring force is driven by the stirring force transmitted from the transmission means.

Some of the objects to be dried that are dried by the microwave drying device maintain a dry state even during drying, and some of them become sticky during the process. The material to be dried that maintains a dry state is so hard that it abrades or damages the stirring means during stirring, shortens the life of the stirring means, and stiffens the material to be dried with high stirring power. However, a material such as ceramic may not withstand the force and may be damaged. Further, since the microwave heating time is high in the drying chamber, the stirring means and the transmission means must be able to withstand the temperature.

In order to solve such a problem, it is considered that the stirring means and the transmission means are made of metal. However, it is necessary to combine the stirring means and the transmission means in the drying chamber for easy attachment / detachment of the stirring means. If the stirring means is not firmly connected or the connecting part becomes loose over time, microwave Discharge may occur during drying, and the material to be dried may deteriorate.

(C) Problem to be Solved by the Invention The present invention is intended to prevent discharge from occurring at the joint between the stirring means and the transmission means in the drying chamber, in order to prevent alteration of the material to be dried.

(D) Means for Solving the Problems A microwave drying apparatus of the present invention is a drying chamber to which a granular or powdery material to be dried is supplied, and a microwave for microwave-drying the material to be dried in the drying chamber. Microwave supplying means for supplying a wave, metal stirring means arranged in the drying chamber for stirring the material to be dried, and inside the drying chamber for transmitting stirring force to the stirring means. It comprises a protruding metal transmission means, a coupling portion for coupling the transmission means and the stirring means in the drying chamber, and a blocking means for preventing microwaves from entering the coupling portion.

(E) Action Both the stirring means and the transmission means are made of metal, and the joint portion between the both is in the drying chamber. However, the microwave is prevented from entering the joint portion by the blocking means. Discharge is prevented from occurring.

(H) Embodiment FIG. 1 shows the structure of a microwave drying apparatus according to an embodiment of the present invention, which comprises a drying apparatus main body (1) and its peripheral mechanism.

The drying apparatus main body (1) is provided with a cylindrical drying chamber (3) having an openable and closable upper lid (2) as a main part.
A supply pipe (4) is connected to the upper left portion of the drying chamber, and the tip of the supply pipe reaches a storage tank (6) for storing the granular or powdery material to be dried (5). Examples of the material to be dried (5) include resin pellets, rice, and chemical powder particles. The resin pellets are molded after being melted, but if the resin pellets are dried prior to such melt molding, the subsequent molding will be performed well. In this embodiment, resin pellets are selected as the material to be dried (5). A suction hopper (7) is connected to the center of the upper lid (2) of the drying chamber (3). A filter wire mesh fixing (8a) having a mesh smaller than the material diameter of the material to be dried (5) and a filter paper (8) are arranged in the hopper, and the poppet valve (9) is located above the filter paper. ) Is provided. A suction blower (11) is connected to the suction hopper (7) above the poppet valve (9) via an intake pipe (10). In this case, when the blower (11) is driven while the poppet valve (9) is driven to open, the intake action of the blower (11) causes the intake pipe (10), the suction popper (7), and the drying chamber (3). ) To the supply pipe (4), and the material to be dried (5) in the storage tank (6) reaches the drying chamber (3) through the supply pipe (4). The material to be dried (5) is in the drying room (3)
At that time, it falls due to its own weight and accumulates in the drying chamber.

In the drying chamber (3), microwaves are supplied from the magnetron (12) through the waveguide (13) to the inside of the drying chamber (3), and the bottom wall surface is covered with the microwave as shown in detail in FIGS. 2 and 3. A metal stirrer (15), which is a stirring means for stirring the dried product (5), is provided. Such a stirrer (15) has a metallic boss (15a) (ceramics boss (15b) is added).
In the upper recess (15c) in the boss, the metallic transmission means, that is, the drive shaft (14a) from the motor (14) outside the drying chamber (3) to the inside of the drying chamber (3). The tip (1b) is internally fitted so that the stirring drive force of the motor (14) is transmitted to the stirring body (15) via the drive shaft (14a), and the stirring body (15) dries the stirring drive force. Material (5) is stirred. In the metallic boss (15a), below the joint between the upper recess (15c) and the tip (14b) of the drive shaft (14a), microwaves are prevented from entering the joint. A blocking means, that is, a microwave choke space (15d) is formed so as to surround the drive shaft (14a), and therefore, the boss (15a) of the metallic stirrer (15) and the drive shaft (14a) are connected to each other at the connecting portion. However, since microwaves do not reach there, microwave discharge does not occur, and deterioration of the material to be dried (5) due to microwave discharge is prevented. A microwave choke space (3a) is also formed on the outer surface of the bottom wall of the drying chamber (3) so as to surround the drive shaft (14a), and a drive shaft through hole (3b) in the bottom wall of the drying chamber (3). The microwave is prevented from leaking from the outside. The structure of the choke space (3a) functions as a bearing for the drive shaft (14a). Further, between the lower end of the metallic boss (15a) and the drive shaft (14a), a sleeve made of Teflon or the like having a small dielectric loss is formed so that microwave discharge is not similarly generated due to contact between the two. 3c) is provided between the drive shaft through hole (3d) and the drive shaft (14a) in the bottom wall of the drying chamber (3) and a sleeve (3c) made of Teflon or the like with a small dielectric loss for the same purpose. Is provided. Further, a washer (3e) such as Teflon having a small dielectric loss is interposed between the metallic boss (14a) and the bottom wall of the drying chamber (3) for the same purpose. In this case, such washer (3e) is
A ring (3f) made of hard ceramics is fixed to the periphery so that the material to be dried (5) that has entered between the 5) and the bottom wall of the drying chamber (3) does not get hit and wear. There is. The upper end of the ring (3f) is located below the upper end of the washer (3e) by a dimension l as shown in FIG.
The ring (3f) is not in contact with the boss (15a). However, the dimension 1 is such that the material to be dried (5) does not enter here. The stirrer (15) and the washer (3e) are detachable so that the inside of the drying chamber (3) can be easily cleaned by opening the upper lid (2).

Next, on the side wall of the drying chamber (3), a level sensor (1
6) and a temperature sensor (17) such as a thermistor. The level sensor (16) detects whether or not a predetermined amount of the material to be dried (5) has accumulated in the drying chamber (3), and the temperature sensor (17) detects the temperature of the material to be dried (5). . A compressor (19) is connected to the left bottom of the drying chamber (3) via an intake valve (18), and an exhaust valve (20) is provided on the upper lid (2) of the drying chamber (3). . Driving these compressors (19) and intake valves (18) and exhaust valves (20)
Is opened at the time of drying the material to be dried (5) by microwaves, etc., and the steam generated at the time of drying is discharged to the outside through the exhaust valve (20) together with the air from the compressor (19). .

Further, a discharge valve (21) is provided on the right bottom portion of the drying chamber (3), and the discharge valve is opened when discharging the dried object (5) to be dried. The material to be dried (5) discharged based on the opening of the discharge valve (21) falls through the discharge pipe (22) into the lower preliminary chamber (23) and accumulates therein. A temperature heater (24) is arranged on the lower inclined wall of the preliminary chamber, and a level sensor (26) having a rotating body (25) is provided in the preliminary chamber (23). Such a level sensor (26) normally rotates the rotating body (25), and
Even if an attempt is made to rotate the rotating body (25) by accumulating a small amount of the dried object (5) inside 3), the dried object (5) becomes a load and the rotating body (25) is satisfied. When it cannot rotate, it outputs a predetermined signal to detect that the material to be dried (5) has accumulated a slight predetermined amount.

The lower part of the spare chamber (23) is connected to another suction hopper (27) located higher than the spare chamber (23) through a transfer pipe (28). Like the suction hopper (7), the suction hopper (27) is also provided with a filter wire net (29) and a filter paper (29) having a mesh smaller than the material diameter of the material to be dried (5), and A poppet valve (30) is provided above the filter paper. The suction hopper (27) is provided above the poppet valve (30).
The intake blower (11) is also connected via an intake pipe (31). In this case, if the blower (11) is driven with the poppet valve (30) opened, the blower (1)
The intake action of 1) is the intake pipe (31), suction hopper (27)
To the transfer pipe (28) through the auxiliary chamber (23)
The material to be dried (5) accumulated in the above reaches the suction hopper (27) through the transfer pipe (28). When the material to be dried (5) reaches the suction hopper (27), it falls into the hopper by its own weight. Further, in the suction hopper (27), the heat retaining heater (32) is arranged on the lower inclined wall, and the open / close valve (33) is provided at the lower end.
Is provided, and upper and lower limit level sensors (34) (35) are arranged at the upper and lower portions. Open / close valve (33)
When the object to be dried (5) falls into the suction hopper (27) when the suction action is performed during the opening of the suction hopper (2)
The material to be dried (5) collects in 7), while the open / close valve (33)
When the opening is opened, the material to be dried (5) thus accumulated falls downward to reach the next-stage processing section, and the material to be dried (5), that is, resin pellets dried in such processing section is melt-molded. It

FIG. 5 shows a circuit of the microwave dryer, and a microcomputer (36) of Sanyo Denki Co., Ltd., product number LC-65PG23 is provided as a main control unit, and the computer is a dryer unit (1). Information from the operation section (37) arranged on the front surface of the vehicle, temperature information from the temperature sensor (17), and the various level sensors (16) (26) (34) (3)
5) Based on the information from the above, etc., the magnetron (1
2), motor (14), intake valve (18), exhaust valve (20), compressor (19), discharge valve (21), heat retention heater (24)
(32), suction blower (11), poppet valve (9) (30),
The on-off valve (33) is drive-controlled.

FIG. 6 shows a flow chart of an operation program incorporated in the microcomputer (36), and the operation of the microwave dryer will be described below with reference to the chart.

After turning on the power, go through the S1 step and then use the normal S2, S3, S3a,
4 and S5 are cyclically executed. In step S1, initial setting operation is performed. That is, all the writable areas in the microcomputer (36) are cleared, and the magnetron (12), motor (14), compressor (19), heaters (24) (32), suction blower ( 11) is placed in the drive stopped state and the intake valve (1
8), exhaust valve (20), discharge valve (21), poppet valve (9)
(30) and the on-off valve (33) are placed in the closed state. In S2 step, operation information from the operation section (37) is input, and in S3 step, the lower limit level sensor (35) determines whether or not the material to be dried (5) is accumulated in the suction popper (27). , In the S3a step, the level sensor (2
Based on the detection of 6), it is determined whether or not the dried object (5) is accumulated in the preliminary chamber (23) in a slight predetermined amount. In step S4, it is checked whether or not the start flag is set in the computer (36), and in step S5, it is determined whether or not the start key is currently operated by the operation section (47) based on the input information in step S2. It

When the material to be dried (5), which is a resin pet, is melt-molded and the material to be dried (5) is dried in advance so that such molding can be performed well, first, the operation part (37) is hand,
A desired drying time and a desired drying temperature are set by key operation within a range of 20 to 60 minutes and within a range of 70 to 170 ° C., and the continuous switch (38) is turned on. These operation information are input in step S2. After that, when the start key is operated on the operation unit (47), such information is similarly input in step S2, an affirmative judgment is made in step S5, the start flag is subsequently set in step S6, and then in step S7. Then, the drive control of each of the heat retention heaters (24) (32) is started. That is, each of the heat retaining heaters (24) (32) is intermittently driven at a desired ratio so that the insides of the preliminary chamber (23) and the suction hopper (27) are approximately maintained at the set drying temperature, and therefore the preliminary chamber is The inside of (23) and the suction hopper (27) is kept at the above temperature.

Then, steps S8, S9, and S10 are sequentially executed. S8
In step S, it is checked whether or not the transport flag in the computer (36) is set (in this case, it is checked that it is not set.) In step S9, the operation of supplying the material to be dried (5) to the drying chamber (3) Is executed. That is, the poppet valve (9) is opened and the suction blower (11) is driven,
The material to be dried (5) is supplied from the storage tank (6) into the drying chamber (3) by the suction action of the blower (11), and the motor (14) is driven to rotate the agitator (15), The top surface of the material to be dried (5) supplied into the drying chamber (3) is aligned with a smooth horizontal surface. In step S10, whether or not the upper surface of the object to be dried (5) reaches the position of this sensor (16) by the detection of the level sensor (16) and the object to be dried (5) has accumulated in the drying chamber (3) by a predetermined amount. Is determined (in this case, it is determined that the predetermined amount is not accumulated).

Then, the steps S2, S3, S3a, S4, S11, and S8 to S10 are cyclically executed. At this time, in step S11, it is checked whether or not the post-supply flag is set in the computer (36). Then, a predetermined amount of the material to be dried (5) is accumulated in the drying chamber (3), and if this is determined in step S10, then S12,
The S13 step is executed. In step S12, the operation of supplying the material to be dried (5) to the drying chamber (3) executed in step S9 is ended. In step S13, the supply end flag is set.

Then, steps S2, S3, S3a, S4, S11, and S14 to S17 are cyclically executed. At this time, in step S14, it is checked whether or not the drying end flag is set in the computer (36), and in step S15, the drying operation is executed. That is, the magnetron (12) is intermittently driven depending on whether or not the temperature of the material to be dried (5) detected by the temperature sensor (17) has reached the set drying temperature, and the material to be dried (5) reaches the drying temperature. It is maintained and microwave-dried, and the motor (14) is re-driven to rotate the semiconductor (15) to stir so that the material to be dried (5) is evenly dried and the compressor (19). And the intake valve (18) and the exhaust valve (20) are opened, so that the water vapor generated from the material to be dried (5) is discharged to the outside. Further, in the step S15, the time of the drying elapsed time is started together with such a drying operation. In step S16, it is determined whether or not the drying elapsed time has reached the set drying time, and in step S17, whether or not the transport flag is set is checked as in step S8.

When the elapsed dry time reaches the set dry time, S1
After 6 steps, S18 and S19 steps are executed. In step S18, the time of the drying operation and the elapsed time of drying executed in step S15 is ended, and the time counted is reset. In step S19, the drying end flag is set.

Then, after steps S17, S2, S3, S3a, S4, S11, and S14, steps S20, S21, S22, S23, and S24 are sequentially executed. In step S20, it is checked whether or not the ejection flag in the computer (36) is set. In step S21, the spare room (2
It is judged whether or not a small amount of the material to be dried (5) has already accumulated in 3). In step S22, when the heat retaining operation (described later) in the drying chamber (3) is being performed, this is ended and the discharge flag is set. In step S23, the material to be dried (5) is placed in the preliminary room (23) in step S21.
Is allowed to be newly discharged from the drying chamber (3) to the preliminary chamber (23) because a predetermined amount is not accumulated, and the step S23 is performed. Then, the operation of discharging the dried material (5) from the drying chamber (3) to the preliminary chamber (23) is executed. That is, the discharge valve (21) is opened, the motor (14) is continuously driven to rotate the stirring body (15), and the stirring body (15) is rotated in accordance with the rotation of the stirring body (15). 15) The material to be dried (5) in the vicinity is pushed to the surroundings, and the material to be dried (5) falls from the discharge valve (21) through the discharge pipe (22) and is discharged to the preliminary chamber (23). Material to be dried discharged in this way (5)
Since the preliminary chamber (23) is kept warm from the step S7, it is possible to prevent the material to be dried (5) from absorbing moisture again due to natural cooling without being naturally cooled. Further, in step S23, the time counting of the elapsed time of such discharge is started. In step S24, the elapsed discharge time is set to a predetermined discharge time (this is a time sufficient to discharge all the predetermined material to be dried (5) accumulated in the drying chamber (3)). It is determined whether or not it has arrived.

After that, S2, S3, S3a, S4, S11, S14, S20, S23, S24,
When each step of S17 is cyclically executed and a slight predetermined amount of the material to be dried (5) is accumulated in the preliminary chamber (23) as a result of the discharge, steps S3a to S25, S26, S2 in this cycle are performed.
7, each step of S28 is sequentially executed. In step S25, the transport flag is set, and in step S26, when the material to be dried supply operation is being executed in step S9, the operation is stopped. In step S27, an operation of transporting the dried object (5) to the suction hopper (27) from the preliminary chamber (23) which is kept warm is executed. That is, the poppet valve (30) is opened to drive the suction blower (11), and the suction action of the blower (11) causes the preliminary chamber (23).
The material (5) to be dried is conveyed from the suction hopper (27).
Since the suction hopper (27) keeps the temperature of the suction hopper (27) kept warm from the above-mentioned S7 step, the material to be dried (5) conveyed in this way is not naturally cooled, and the material to be dried (5) absorbs moisture again. Is prevented. In step S28, the suction hopper (27) is detected by the upper limit level sensor (34).
Then, it is determined whether or not the material to be dried (5) has accumulated up to the position of such a sensor (in this case, it is determined to be no).

Then S4, S11, S14, S20, S23, S24, S17, S27, S28
The respective steps of (1) are circulated, and during this period, the discharging operation to the preliminary chamber (23) and the conveying operation to the suction hopper (27) are processed in parallel, and the material to be dried (5) discharged to the preliminary chamber (23) is processed. Is immediately conveyed to the suction hopper (27).

Then, when the discharge elapsed time reaches a predetermined discharge time (all the material to be dried (5) is discharged from the drying chamber (3) to the preliminary chamber (23)), then S29, S30, and S31 Each step is sequentially executed. In step S29, the discharge operation and discharge elapsed time, which have been executed in step S23, have been timed, and the time measured has been reset. S30
In the step, all of the above-mentioned supply end flag, drying end flag, and discharge flag are reset. In step S31, it is determined whether or not the continuous switch (38) is turned on in the operation section (37).

In this case, the continuous switch (38) is in the ON state, and after the step S17, the steps S4, S11, S8, S27 and 28 are cyclically executed. Then, when the material to be dried (5) in the preliminary chamber (23) is transported and the material to be dried (5) is accumulated in the suction hopper (27) to the position of the upper limit level sensor (34), the steps S28 to S32 are performed. , S33 step is executed. S
In step 32, the carrying operation executed in step S27 is stopped, and in step S33, the carrying flag is reset.

Thus, the material to be dried (5) thus accumulated in the suction hopper (27) is melt-molded in the next-stage processing section. This is executed when an external command signal P for commanding melt molding is given to the computer (36) in a state where the material to be dried (5) is accumulated up to the position of 34). That is, at this time, the opening / closing valve (33) is opened by the computer (46), and the material to be dried (5) is discharged from the suction hopper (27) to the next stage processing section. The on-off valve (33) is closed again when all the material to be dried (5) in the suction hopper (27) has been discharged. The released material (5) to be dried is melt-molded in the next-stage treatment section. In this case, the resin pellets, that is, the material (5) to be dried is dried in advance, so that the molding is performed well. .

Here, when the processing capacity of the next-stage processing unit for the melt-molding is slow, the suction hopper (27) and the auxiliary chamber (23) are repeated because the operation of supplying the material to be dried and the operation of conveying the material are repeatedly performed. The material to be dried (5) remains in the area. Then, in a state where the material to be dried (5) is accumulated in the preliminary chamber (23),
When the material to be dried (5) is about to be discharged from the drying chamber (3), this is determined in step S21, that is, the preliminary chamber (2
It is determined that the material to be dried (5) is accumulated in the predetermined amount more than the predetermined amount in 3), and it is not allowed to newly discharge the material to be dried (5) from the drying chamber (3) to the preliminary chamber (23). Then, the dried object (5) is left in the drying chamber (3) as it is after being dried. If such leaving is simply performed, the material to be dried (5) is naturally cooled and absorbs moisture again even if it is dried, but in the embodiment of the present invention, in order to prevent this, at this time S3
4 steps are executed. That is, in such S34 step,
Exactly the same control as the drying operation in step S15 is performed, and the material to be dried (5) is kept at the set drying temperature by microwave,
Therefore, the material to be dried (5) is prevented from absorbing moisture again in the drying chamber (3).

The above series of operations is ended by turning off the continuous switch (38). That is, when the step S31 is executed at the time of turning off, the step S35 is then executed, the start flag is reset, and the heat retention heaters (24) (32) are stopped. Then S2, S3, S3a, S
4, S5 step is cyclically executed.

(G) Effect of the Invention According to the present invention, microwave discharge is generated at the joint between the metallic stirring means for stirring the material to be dried in the drying chamber and the metallic transmission means for transmitting the stirring force to the stirring means. It is possible to prevent the deterioration and to control the undesired alteration of the material to be dried.

[Brief description of drawings]

The drawings show an embodiment of the present invention, FIG. 1 is a sectional view, FIGS. 2 and 3 are sectional views and exploded sectional views showing details of the vicinity of a stirring body, respectively, and FIG. 4 is a sectional view of a washer, FIG. 5 is a circuit diagram, and FIG. 6 is a flow chart of an operation program of the microcomputer. (3) ... drying room, (12) ... magnetron, (15) ...
… Agitator, (14a) …… Drive shaft, (15d) …… Microwave choke space, (3e) …… Washer, (3f) …… Ring.

Continuation of the front page (56) References JP-A-SHO 64-58511 (JP, A) JP-A-SHO 63-231908 (JP, A) REAL SHO-SHO 56-144290 (JP, U)

Claims (1)

[Claims] 1. A drying chamber to which a granular or powdery material to be dried is supplied, a microwave supply means for supplying a microwave for microwave-drying the material to be dried to the drying chamber, and the inside of the drying chamber. A metallic stirring means arranged to stir the object to be dried; a metallic transmission means coupled to the stirring means and projectingly arranged in the drying chamber for transmitting a stirring force to the stirring means; A microwave drying device, comprising: a joining part for joining the stirring means in the drying chamber; and a blocking means for blocking microwaves from entering the joining part.