JPH02305608A - Microwave drier - Google Patents

Abstract

PURPOSE:To control change of quality of a matter to be dried, by a method wherein a hindering device for hindering an invasion of a microwave is provided on a joining part between a metallic agitating device for agitating the matter to be dried and a metallic transmitting device transmitting agitating force. CONSTITUTION:A microwave is fed within a drying chamber 3 through a waveguide 13 from a magnetron and a metallic agitating body 15 for agitating a matter 5 to be dried is provided on a bottom wall part. The agitating body 15 possesses a metallic boss 15a, the tip 14b of a metallic driving shaft 14a arriving at the inside of the drying chamber 3 from a motor 14 which is outside of the drying chamber 3 is joined to a recessed part 15c of the upper part of the inside of the said boss through fitting into the recessed part 15c and the matter 5 to be dried is agitated. A hindering device hindering the microwave from invading into such a joining part, that is, a microwave choking space 15d is formed on the lower part of the joining part between the recessed part of the upper part and the tip 14b of the driving shaft 14a so as to surround the driving shaft 14a, in the metallic boss 15a. Therefore the matter 5 to be dried can be prevented from changing in quality with a microwave discharge.

Description

[Detailed description of the invention] (b) Industrial application field The present invention relates to microwave drying equipment.

(b) Prior Art Japanese Patent Application No. 1-47803 discloses a microwave drying apparatus that applies microwaves to a drying chamber into which the material to be dried is supplied to microwave-dry the material to be dried. The same housing is provided with a stirring means for stirring the material to be dried in the drying chamber so that the material to be dried is evenly dried. The stirring means is connected to a transmission means extending from outside the drying chamber into the drying chamber, and the Igt stirring means is driven by stirring force transmitted from the transmission means.

Now, if these stirring means and transmission means are made of metal, the connecting part between these metallic stirring means and transmission means is located in the drying chamber where microwaves are supplied. There is a risk that microwave discharge will occur between the two, resulting in deterioration of the quality of the material to be dried.

(c) Problems to be Solved by the Invention The present invention is directed to preventing microwave discharge from occurring at the joint between the stirring means and the transmission means in the drying chamber in order to prevent deterioration of the quality of the material to be dried.

(d) Means for Solving the Problems The microwave drying apparatus of the present invention includes a drying chamber into 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. a microwave supply means for supplying waves; a metallic stirring means arranged in the drying chamber and stirring the material to be dried; and a metallic transmission means coupled to the stirring means and transmitting stirring force to the stirring means. and a blocking means for preventing microwaves from entering a joint between the transmitting means and the stirring means.

Although both the agitation means and the transmission means are made of metal, and the joint between them is located inside the drying chamber, the microwave can be prevented from entering the joint by the blocking means. Discharge is prevented from occurring.

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

The main part of the drying device (1) is provided with a cylindrical drying chamber (3) having a top lid (2) that can be opened and closed. A supply pipe (4) is connected to the upper left part of the drying chamber, and the tip of the supply pipe reaches into a storage tank (6) in which granular or powdery material to be dried (5) is stored. The materials to be dried (5) to be refused include, for example, resin pellets, rice, and powdered pharmaceutical products. Resin pellets are molded after being melted, but if the resin pellets are dried prior to melt molding, subsequent molding will be better.In this example, the material to be dried (5) was Resin pellets are selected. Further, a suction hopper (7) is connected to the center of the upper lid (2) of the drying chamber (3). A filter wire mesh (8a) and a filter paper <8) having a diameter smaller than the material diameter of the material to be dried (5) are disposed in the hopper, and a poppet valve (8a) is located above the filter paper.
9) is provided. And such a poppet valve (9)
At the upper part of the suction hopper (7), a suction blower (11) is connected to the suction hopper (7) via an intake pipe (10). In this case, if the blower (11) is driven with the blow valve (9) open, the blower (11) will be turned off.
) suction pipe (10), suction hopper (7)
and extending through the drying chamber (3) to the supply pipe (4);
The material to be dried (5) in the storage tank (6) is the supply pipe (4)
The drying room (3) is reached through the drying room (3). When the material to be dried (5) reaches the drying chamber (3), it falls and accumulates therein due to its own weight.

In the drying chamber (3), microwaves are supplied to the interior from the magnetron (12) through the waveguide (13), and as shown in detail in Figs.
A metal stirring body (15) is provided as a stirring means for stirring the material to be dried (5). The stirring body (15) has a metal boss (t5m> to which a ceramic boss (15b) is attached), and an upper recess (15c) in the boss is provided with a metal boss (t5m) that is attached to the outside of the drying chamber (3). A metal transmission means, that is, a drive shaft (14a) leading from the motor (14) to the inside of the drying chamber (3), is internally connected to the drive shaft (14b).
The stirring driving force of 14) is transmitted to the stirring body (15) via the drive shaft (14g), and the material to be dried (5) is stirred by the stirring body (15). In the metal boss (15a), a block is provided below the joint between the upper recess (15c) and the tip (14b) of the drive shaft (14m) to prevent microwaves from entering the joint. A microwave choke space (15d) is formed to surround the drive shaft (14g), so that the position of the metallic stirring body (15) is connected to the drive shaft (14a) at the joint. Although they come into contact with each other due to bonding, the microwave does not reach there, so no microwave discharge occurs, and the material to be dried (5) is prevented from changing in quality due to the microwave discharge. 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) is formed. Microwaves are completely prevented from leaking to the outside. The structure of the choke space (3a) also has the function of bearing the drive shaft (14a). In addition, the metal boss (15
A sleeve (3C) made of Teflon or the like with low dielectric loss is provided between the lower end of a) and the drive shaft (14a) to prevent microwave discharge from occurring due to contact between the two. , the drive shaft through hole in the bottom wall of the drying chamber (3) (
3d) and the drive shaft (14a), a sleeve (3d) made of Teflon or the like having low dielectric loss is provided for the same purpose.

Furthermore, a washer (3e) made of Teflon or the like having a small dielectric loss is interposed between the metal boss (14g) and the bottom wall of the drying chamber (3) for the same purpose. In this case, the washer (3Q) is made of a hard material so that the material to be dried (5) that has entered between the agitator (15) and the bottom wall of the drying chamber (3) does not hit and wear out. Ring made of ceramics (
3f) is fixed around the surrounding area. The upper end of the cutting ring (3f) is larger than the upper end of the washer v (3e) as shown in Figure 4! It is located on the lower side of the tower to prevent the ring (3f) from coming into contact with the boss (15a). However, the dimensions are such that the material to be dried (5) does not fit there. And the stirring body (15) and washer (3e)
is removable, making it easy to clean the inside of the drying chamber (3) by opening the top cover (2).

Next, a level sensor (1) is installed on the side wall of the drying chamber (3).
6) and a temperature sensor (17) such as a thermistor are arranged. The level sensor (16) detects whether 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). .

In addition, a compressor (19) is connected to the left bottom of the drying chamber (3) via an intake valve (18), and the drying chamber (3)
An exhaust valve (20) is provided on the top cover (2). The driving of the compressor (19) and the opening of the intake valve (18) and the exhaust valve (20) are performed when the material to be dried (5) is dried using microwaves, and the water vapor generated during drying is transferred to the compressor. Exhaust valve (20) along with air from (19)
) and is discharged to the outside.

Furthermore, a discharge valve (21) is provided at the bottom right of the drying chamber (3), and the discharge valve discharges the dried material (
5) It is opened when discharging. The material to be dried (5) discharged upon opening of the discharge valve (21) falls through the discharge vibrator (22) and accumulates in the preliminary chamber (23) below. A heat retaining heater (24) is arranged on the lower inclined wall of the preparatory chamber, and a level sensor (26) having a rotating body 25) is provided in the preparatory chamber (z3). Such a level sensor (26) normally rotates the rotating body (25), and when a small predetermined amount of the material to be dried (5) accumulates in the preliminary chamber (23), the rotating body (25) tries to rotate. However, when the object to be dried (5) is a load and the rotating body (25) cannot be rotated satisfactorily, a predetermined signal is output and a predetermined amount of the object to be dried (5) is accumulated. detect that there is a

The lower part of the preliminary chamber (23) is connected to another suction hopper (27) located at a higher place than the preliminary chamber (23).
) are connected through. Similar to the suction hopper (7), the suction hopper (27) also has a filter wire mesh (29a) having a mesh smaller than the material diameter of the material to be dried (5).
) and a filter paper (29) are arranged, and a poppet valve <30> is provided above the filter paper. And, in the upper part of the poppet valve (30),
The suction blower (11) is also connected to the suction hopper (27) via an intake vibrator (31). In this case, the poppet valve (30) is opened and the blower (11
), the suction action of the blower (11) extends to the conveying vibrator (28) via the suction pipe (31) and the suction hopper (27), and the drying material accumulated in the preliminary chamber (23) is removed. 5) passes through the conveyance vibrator (28) and reaches the suction hopper (27). The material to be dried (5) is transported to the suction hopper (
27), it falls into the hopper due to its own weight. In the suction hopper (27), a heat insulating heater (32) is arranged on the lower inclined wall, an on-off valve (33) is provided at the lower end, and upper and lower limit level sensors (34) ( 35) has been placed completely. The above on-off valve (3
In opening step 3), when the suction action works and the material to be dried (5) falls into the suction hopper (27), the material to be dried (5) accumulates in the suction hopper (27), while the opening/closing valve ( When 33) is opened, the dried material (5) accumulated like this
falls downward and reaches the next processing section, where the dried material (5), ie, the resin pellet, is melt-molded and molded.

Fig. 5 shows the circuit of the microwave drying device, in which the main control section is a part number LC-65PG23 manufactured by Sanyo Electric Co., Ltd.
A microcomputer (36) is provided, and the computer receives operation information from the operation section (37) disposed on the front of the drying device main body (1) and temperature information from the temperature sensor (17). , the above various level sensors (16
) (26) (34) (35) Based on information 11NIF, the above magnetron (12), motor (10, intake valve (18), exhaust valve (20), compressor (19)
, discharge valve (21), insulation heater (24) (32), suction blower (11), poppet valve (9) (30), on-off valve (
33).

FIG. 6 shows a flowchart of the I1 production program incorporated in the microcomputer (36), and the operation of the microwave drying apparatus will be explained along the IT chart.

After the ti throw, after the Sl step, the normal S2, S3, S
3a% Each step of S4 and S5 is executed cyclically. S
In the first step, an initial setting operation is performed. In other words, all writable areas in the microcomputer (36) are cleared, and the magnetron (12), motor (14), heater tube (19), and heater (2) are cleared.
4) (32), the suction blower (11) is placed in a drive stopped state, and the intake valve (1B), exhaust valve (20), discharge valve (21), poppet valve (9) (30), on-off valve ( 33
) are each placed in a closed state. In the S2 step, the operation information from the operation section (37) is fully input, and in the S3 step, the suction hopper (
In step 33a, it is determined whether or not the material to be dried (5) is accumulated in the pre-chamber (23) based on the detection by the bell sensor (26) described above. In step S4, it is checked whether the start flag is set in the computer 36), and in step S5, the start flag is currently set by the operation unit (37) based on the information input in step S2. It is determined whether or not a key is being operated.

Therefore, when melt-molding the object to be dried (5), which is a resin pellet, in order to dry the object to be dried (5) in advance so that such molding can be performed well, first, the operating section (37) is Then, set the desired drying time and drying temperature within the range of 20 to 60 minutes and within the range of 70 to 170° C. using the keys, and turn on the continuous switch (38). These operating information are input in step S2. After this, the operation section (37)
When the start key is operated at step 82, the information is similarly inputted at step S5, an affirmative judgment is made at step S5, the start flag is set at step S6, and each of the above-mentioned heat retention heaters ( 24) (32
) drive control is started. That is, the preliminary room (23)
and each of the above-mentioned heat retention heaters (24) (3) so that the inside of the suction hopper (27) is maintained approximately at the set drying temperature.
2) is intermittently driven at a desired ratio 4. Therefore, the preliminary chamber (23)
And the inside of the suction hopper (27) is kept warm at the above temperature.

Next, steps S8, S9, and S10 are sequentially executed. In step S8, it is checked whether the conveyance flag in the computer (36) is set (in this case, it is checked that it is not set), and in step S9, the material to be dried (5) is supplied to the drying chamber (3). Action is performed.

That is, the poppet valve (9) is opened and the suction blower (11) is opened.
) is driven, and the storage tank (
The material to be dried (5) is supplied from 6) into the drying chamber (3),
In addition, the motor (14) is driven to rotate the stirrer (15), and the upper surface of the dried material (5) that has been completely supplied into the drying chamber (3) is aligned with a smooth horizontal surface.In step 510, the above-mentioned The object to be dried (5) is detected by the level sensor (16).
) reaches the position of this sensor (16) and the drying chamber (
3) It is determined whether or not a predetermined number of items to be dried (5) have accumulated in the chamber (in this case, it is determined that a predetermined number of items have not accumulated).

After that, S2, S3,! 33a%34.811, S8~
Each step of S10 is executed cyclically. At this time, in the Sll step, it is checked whether the supply end flag in the computer (36) is set. When a predetermined number of items to be dried (5) accumulates in the drying chamber (3) and this is determined in step S10, step Si2.313 is then executed. In step S12, the operation of supplying the material to be dried (5) to the drying chamber (3) executed in step S9 is completed. In step S13, the supply end flag is set.

After that, S2, S3, S3a, 84.811, S14~
Each step and knob of S17 can be executed in a circular manner. At this time, S1
In step 4, it is checked whether the drying end flag in the computer (36) is set, 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 object to be dried (5) detected by the temperature sensor (17) has reached the set drying temperature, and the object to be dried (5) is brought to the drying temperature. At the same time, the motor (14) is driven again and the agitation body (15) is rotated to agitate the material (5) to be dried evenly, and the drying material (5) is dried evenly. 19) and the intake valve (18) and exhaust valve (20>) are not fully opened, and the water vapor generated from the material to be dried (5) is discharged to the outside.Furthermore, in step S15, along with such drying operation, , measurement of the elapsed drying time is started.In step S16, it is determined whether or not the elapsed drying time has reached the set drying time, and in step S17, as in step S8, it is determined whether or not the conveyance flag is set. It can be investigated.

Therefore, when the elapsed drying time reaches the set drying time, S
After 16 steps, 518.819 steps can be executed. At step 818, the drying operation executed at step S15 and the measurement of elapsed drying time are terminated, and the time that has been counted is reset.

In step S19, the drying end flag is set.

And S17, S2, S3, S3a, 84, SLl,
After passing through 514 steps, S20, S21, S22
, S23, and S24 are sequentially executed. S2
In step 0, it is checked whether or not the discharge flag in the computer (36) is set. In step S21, it is determined whether or not a predetermined amount of drying material (5) has already accumulated in the preliminary chamber (23) based on the detection by the level sensor (26). In step S22, if a heat-retaining operation (described later) is being performed in the drying chamber (3), this is terminated and the discharge flag is set. In step S23, the material to be dried (5
) is not accumulated at a predetermined level, and therefore the drying material <5) is allowed to be newly discharged from the drying chamber (3) to the reserve chamber 23), and such S23 In this step, an operation is performed to discharge the dried material (5) from the drying chamber (3) to the preliminary chamber (23). That is,
When the discharge valve (21) is opened, the motor
4) is subsequently driven to rotate the stirring body (15),
As the agitator (15) rotates, the object to be dried (5) near the agitator (15) is pushed to the surroundings, and the object to be dried (5)
is discharged from the discharge valve (21) via the discharge pipe (22) into the preliminary chamber (23). The material to be dried (5) discharged in this way does not naturally cool down because the pre-chamber (23) has been kept warm since step S7, and the material to be dried (5) is cooled down again as it cools naturally. Moisture absorption is prevented. Furthermore, in step S23, the elapsed time of such discharge is started to be counted. In step S24, the discharge elapsed time is a predetermined discharge time (this is a predetermined amount of drying material (5) accumulated in the drying chamber (3)).
It is possible to judge whether or not the amount of time has been reached (this is sufficient time to completely expel the liquid).

After that, S2, S3, S3a%94, S11, S14.
320, S23.924.817 are executed in circulation, and when a small predetermined amount of the material to be dried (5) accumulates in the preparatory chamber (23) as a result of the above-mentioned discharge, steps S3m to S25 are executed in the circulation. .826, 827, and S28 are sequentially executed. In step S25, a conveyance flag is set, and in step 326, if the drying material supply operation is being executed in step S9, the operation is stopped. In step S27, an operation is carried out to transport the dried material (5) from the warmed preliminary chamber (23) to the suction hopper (27).

That is, the poppet valve (30) is opened and the suction blower (1) is opened.
1) is driven, and the material to be dried (5) is transported from the preliminary chamber (23) to the suction hopper (27) by the suction action of the blower (11). The material to be dried (5) transported in this way is
The suction hopper (27) has been kept warm since step S7. This prevents natural cooling and prevents the material to be dried (5) from absorbing moisture again. 828
In step, it is determined by the detection of the upper limit level sensor (34) whether or not the material to be dried (5) has accumulated in the suction hopper (27) up to the position of the sensor (in this case, it is determined that no). ).

After that, S4, S11, Si2.820.823, S2
Steps 4, S17, S27, and S28 are executed cyclically, and during this period, the discharge operation to the preliminary chamber (23) and the conveyance operation to the suction hopper (27) are processed in parallel, and the
) The material to be dried (5) is immediately transferred to the suction hopper (2
7).

Then, when the elapsed discharge time reaches a predetermined discharge time, all of the material to be dried (5) is discharged from the drying chamber (3) to the preliminary chamber (23)), and then the drying material (5) is discharged from the drying chamber (3) to the preliminary chamber (23).
Each step of 331 is executed sequentially. In step S29, the ejecting operation executed in step S23 and counting of elapsed ejecting time are completed, and the elapsed time is reset. In step S30, all of the above-mentioned supply end flag, drying end flag, and discharge flag can be reset. In step S31, it is determined whether or not the continuous switch (38) is turned on using the operation section (37).

In this case, the continuous switch (38) is in the on state,
After that, after going through 517 steps, S4, Sll, S8 .
Steps 827 and S28 are executed cyclically. Then, when the material to be dried (5) in the preliminary chamber (23) is transported and the material to be dried (5) accumulates in the suction hopper (27) up to the position of the upper limit level sensor (34), step S28... Steps S32 and S33 can be executed from the step. In step S32, the conveyance operation executed in step 827 is stopped, and in step S33, the conveyance flag is reset.

The material to be dried (5) thus collected in the suction hopper (27) is melt-molded in the next processing section.
This is the upper limit level sensor (3) inside the suction hopper (27).
The computer (
36) is executed when given within. That is, at this time, the opening/closing valve (33) is opened by the fan unit (36), and the material to be dried (5) is discharged from the suction hopper (27) to the next stage processing section. The opening/closing valve (33) is closed again when all of the material to be dried (5) in the suction hopper (27) is discharged. Then, the discharged material to be dried (5) is melt-molded in the next processing section, and in this case, the resin pellets, that is, the material to be dried (5) are dried in advance, so that the molding can be performed well. .

Here, if the processing capacity of the next-stage processing section for the melt-molding is slow, the operations from the drying material supply operation to the conveyance operation are performed repeatedly, so that the suction hopper (27) and the preparatory chamber (23) The material to be dried (5) remains accumulated. Therefore, when the material to be dried (5) is accumulated in the preliminary chamber (23) and the material to be dried (5) is further discharged from the drying chamber (3), this is determined by the S21 step and is not executed. In other words, if the predetermined amount or more of the material to be dried (5) has accumulated in the preliminary chamber (23), the material to be dried (5) is transferred from the drying chamber (3) to the preliminary chamber (23).
It is determined that the new discharge is not permitted. Then, the dried material (5) is left as it is in the drying chamber (3) even after drying. If the material to be dried (5) is simply left to stand, it will naturally cool down and absorb moisture again even after being dried, but in the embodiment of the present invention, 834 steps are executed to spin this material. In other words, decline S
In step 34, the same control as the drying operation in step S15 is no longer possible, and the object to be dried (5) is kept warm at the set drying temperature using microwaves, so that the object to be dried (5) is kept in the drying chamber (
3) prevents moisture from being absorbed again.

The series of operations described above is ended by turning off the continuous switch (38). That is, when step 831 is executed at such off time, step 835 is executed next,
The start flag is reset and the respective heat-retaining heaters (24) and (32) are stopped. Then S2
, S3.83m, 84, and S5 steps are executed cyclically.

(G) Effects 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. Therefore, it is possible to prevent the dried material from undesirably changing in quality.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a sectional view, FIGS. 2 and 3 are sectional views and exploded sectional views showing details around the stirring body, respectively, and FIG. 4 is a sectional view of the washer. FIG. 5 is a circuit diagram, and FIG. 6 is a flowchart of the operating program of the microcomputer. (3)...Drying room, (12)...Magnetron, (
15) Stirring body, (14g) Drive shaft, (1
5d)...Microwave choke space, (3e)...
Washer, (3f)...Ring.

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 microwaves for microwave drying the dried material to the drying chamber; Microwaves enter a metallic stirring means for stirring the material to be dried, a metallic transmission means coupled to the stirring means and transmitting stirring force to the stirring means, and a joint between the transmission means and the stirring means. A microwave drying device characterized by comprising: a prevention means for preventing the drying.