JPH0514155Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a clay oven for storing clay for industrial design at a suitable temperature for use.

Prior Art Clay is used to make models of machines, vehicles, etc. to be prototyped. This clay needs to be heated to a certain temperature to make it soft and easy to stretch only when it is being worked into a shape. When using a small amount of this clay, there is no problem, but when making a large model, a large amount of clay was required, and a large furnace was used to heat the required amount. Temperature adjustment was performed using on/off control. In addition, the outlet for taking out the clay was double-opened, making it easy to take out the clay.

Problems that the invention aims to solve When heating a large amount of clay at once in a large furnace like this, it is difficult to make the temperature distribution inside the furnace uniform, and since the temperature is controlled on and off, the temperature fluctuation range is large. . Furthermore, since the outlet is double-opened, the air inside the furnace and the outside air tend to flow, resulting in a significant drop in the temperature inside the furnace and further increasing fluctuations in the temperature inside the furnace. In general, companies that use large quantities of clay manufacture clay according to their own specifications, so the optimum temperature for use is not necessarily constant, and the optimum temperature range is narrow and strict. When the clay temperature decreases, the clay loses its elongation and modeling becomes difficult.
If the temperature was raised a little too high, the ingredients in the clay would separate and paraffin would precipitate out, making it brittle and unusable. For this reason, a furnace that could take out the required amount of clay at an appropriate temperature at any time was desired.

Means for solving the problem: A box-shaped furnace body 1 that has drawers 3 with air circulation holes provided almost evenly on the bottom and can keep the inside warm, and a fan 4 that circulates the air inside the furnace body 1. a heater 5 that increases the air temperature inside the furnace body 1; a temperature sensor 6 that detects the temperature inside the furnace body 1 and outputs a signal; and a triax 8 that controls the heating power of the heater 5. a temperature controller 7 that compares the temperature detected by the temperature sensor 6 with a set temperature and inputs the result to the triax 8; and a first stage safety device that prevents the power supply circuit of the heater 5 from closing when the drive circuit of the fan 4 is open. and next-stage safety circuits 9 and 10 that open the power supply circuit of the heater 5 when the temperature inside the furnace body 1 is abnormal.

Embodiments Hereinafter, embodiments of the present invention will be described based on the drawings. Furnace body 1 is surrounded by double iron plates, and the inside of the wall is filled with heat insulating material all around. Furnace body 1 is formed into a box shape, and casters 2 are attached to the bottom so that it can be moved freely to a desired position. Installation is possible. Several stages of clay storage drawers 3 are built into the furnace body 1 so that the clay storage drawers 3 can be smoothly taken in and out using rollers, and the high temperature air in the furnace does not easily escape. In this drawer 3, clay is stored in a row and a large number of holes are uniformly bored in the bottom of the drawer 3 so that hot air can pass up and down. It is preferable that the number and size of the holes are determined by taking into consideration the retention of clay, the amount of ventilation, etc.

On the inner wall of the furnace body 1, a Shiritzko fan 4 is installed in a drawer 3.
Two arc-shaped heaters 5, in this example 500 W, are attached to surround the outer periphery of the fan. A temperature sensor 6, a thermostat 9, and a temperature fuse 10 are attached to the inner wall of the drawer 3 on the opposite side of the sirotoko fan 4. Power on indicator lamp WL and fan on indicator lamp located on top of furnace body 1 in an easy-to-see position
Fan-on switch PB3 with built-in PL1, fan-off switch PB1 with built-in fan-off indicator lamp GL,
Timer on switch PB2 with built-in timer on indicator lamp PL0, motor ammeter 11, temperature indicating controller 7 that indicates and adjusts the temperature in the furnace, heater ammeter 1
2. Heater on switch PB5 with built-in heater switch on indicator lamp PL2, heater off indicator lamp
A heater cut-off switch PB4 built into the GL2, an abnormal temperature display lamp OL, and a timer T whose time can be adjusted arbitrarily are provided, and a power on/off switch ELB and a power connector are provided on the outside of the furnace body 1. A control circuit board including a triax 8 shown in FIG. 3 is built in the furnace body 1 near the power switch ELB.

Operation The operation will be explained with reference to the control circuit diagram shown in FIG.

First, the temperature indicator controller 7 is set to the appropriate temperature for the clay stored in the clay oven. Each drawer 3 is lined with cotton cloth, and the clay is stored in a row on it.

Preparation for operation Turn on power switches ELB and CP. Wire number C2
AC100V is applied between C3 and C3, the power-on indicator lamp WL, the fan-off lamp GL, and the heater-off lamp GL2 are turned on, and at the same time relay X2 is turned on. Therefore, the b contact of X2 is turned off and wire number C
The circuit between 2 and C17 is opened and the abnormal temperature display lamp is displayed.
OL doesn't light up. Further, the a contact of X2 is turned on, conduction occurs between wire numbers C2 and C22, relay X3 is turned on, the a contact is turned on, and the circuit is maintained.

Direct start fan on Press push button switch PB3 to turn on wire numbers C4 and C14
is made conductive, the indicator lamp PL1 containing the fan lights up, the electromagnetic switch MS1 is turned on, the circuit is held by the a contact, and the drive circuit for the Sirotskov fan 4 is turned on, causing the Sirotskov fan 4 to rotate.
At the same time, the b contact is turned off, the circuit between wire numbers C2 and C9 is opened, and the fan-off indicator lamp GL is turned off.

Fan OFF When the push button switch PB1 is pressed, the circuit between wire numbers C2 and C4 is opened, the indicator lamp PL1 connected to the fan goes out, the electromagnetic switch MS1 is turned off, and the drive circuit of the fan 4 is opened, and the circuit of the fan 4 is opened.
rotation is stopped. At the same time, the b contact of MS1 is turned on, conduction occurs between wire numbers C2 and C9, and the fan off indicator lamp GL is lit.

Heater ON Press push button switch PB5 to turn on wire numbers C10 and C1.
1 is electrically connected. Push button switch PB with fan included
3 is pressed, the electromagnetic switch MS1 is turned on, and the Sirotskov fan 4 is rotating, the a contact of MS1 is turned on, there is continuity between wires C11 and C12, and the temperature inside the furnace is in a normal state. When relay X2 is on, its A contact is on, and the conditions are met that continuity is established between wire numbers C12 and C13 (first safety measure), wire number C10,
C11, C12, and C13 are made conductive, and the indicator lamp PL2 with the heater turned on is turned on. At the same time, the electromagnetic switch MS2 is turned on to maintain the circuit, and the power supply circuit of the heater 5 is made conductive.
AC100V is applied to heat the heater 5. On the other hand, the b contact of MS2 is turned off, the circuit between wire numbers C2 and C15 is opened, and the heater-off indicator lamp GL2 is turned off.

The temperature inside the furnace body 1 rises due to the heating of the heater 5, and the temperature corresponding to the output of the temperature sensor 6 and the set temperature are compared by the temperature indicating regulator 7, and the comparison result is input to the triac 8, and the comparison result is The power of the heater 5 is controlled by varying the voltage based on the voltage. In this example, by adjusting the heating temperature, the temperature is maintained within a range of ±1° C. with respect to the set temperature. The temperature inside the furnace is displayed on the temperature indicator controller 7, and it can be confirmed that the clay has reached the appropriate temperature. and drawer 3
You can make a model by pulling out the required number of clays.

Heater OFF Press push button switch PB4 to switch wire numbers C2 and C10.
The circuit is opened, the heater-on indicator lamp PL2 is turned off, the electromagnetic switch MS2 is turned off, and the heater 5 is turned off.
The power supply circuit is opened and power supply is stopped. At the same time, the b contact of MS2 turns on and wire numbers C2 and C1
5 is closed and the heater OFF indicator lamp GL2 is lit.

Timer operation In order to eliminate wasted waiting time from the start of startup until the set temperature is reached, turn the dial of timer T in advance to set the time for timer operation.

When the push button switch PB2 is pressed, conduction is established between the wire numbers C4 and C5, the timer display lamp PL0 is lit, the timer T is turned on, the a contact is turned on, and the circuit is maintained. Then, after the set time of timer T has elapsed, the timer a contact of timer T is turned on, conduction occurs between wire numbers C4 and C6, and relay X1 is turned on. X1
When the A contact is turned on, conduction occurs between wires C4 and C14, the electromagnetic switch MS1 is turned on, and the Sirotskov fan 4 is rotated. Also, when the wires C10 and C11 are conductive and the furnace temperature is normal, relay X2 is turned on. Since the a contact is on, the electromagnetic switch MS2 is turned on and the heater 5 is heated.

When the furnace is abnormally overheated When the temperature inside the furnace is abnormally high (80℃ in this example), the thermostat 9 installed inside the furnace is activated and the wire number C is activated.
The circuit between X2 and C16 is opened, and relay X2 is turned off. As a result, the circuit between wire numbers C12 and C13 is opened, the electromagnetic switch MS2 is turned off, the heater power supply circuit is opened, and the power supply to the heater 5 is stopped. At the same time, the b contact of X2 is turned on, and conduction occurs between wire numbers C2 and C17, and the abnormal temperature indicator lamp OL lights up to indicate the abnormality to the outside. This is the second safety measure.

When the temperature inside the furnace falls below 80°C, the thermostat 9 is reset and the line between C2 and C16 is opened, but the relay X3 is turned on first and the line between C21 and C
When the a-contact between wire number C and wire number 24 is on, and when relay X2 is turned off, the b-contact is turned on.
Since there is continuity between C24 and C23, relay X4 is turned on and the b-contact between wire numbers C16 and C20 is turned off, relay X2 is turned off and the abnormal temperature indicator lamp OL remains lit.

When the temperature indication controller 7 shows the furnace temperature below 80℃ and presses the push button switch PB5 that turns on the heater, the b contact between wire numbers C2 and C21 turns off, and relay
4 is turned off, the b contact between wire numbers C16 and C20 is turned on, and relay X2 is turned on. When this relay X2 is turned on, the b contact is turned off and the wire numbers C2 and C17
The circuit is opened and the abnormal temperature display lamp OL is turned off.

Furthermore, if the temperature inside the furnace becomes even more abnormally high, in this example, 170°C or higher, the temperature fuse 10 installed inside the furnace will melt, opening the circuit between wire numbers C1 and C2, and stopping all power supply. . This is the third safety measure.

Note that when an overload is applied to the motor of the Shirotsuko fan 4, the thermal relay of MS1 is turned off, and power supply to the Shirotsuko fan 4 and the heater 5 is stopped.

Furthermore, the b contacts of PB3 and PB4 are inserted into the timer circuit, so that the timer circuit can be reset while timer T is in operation. Furthermore, the B contact of PB2 is inserted into the fan circuit so that when the timer T is turned on, the Sirotskov fan 4 and heater 5 are not operated.

Effects As detailed above, in this invention, temperature control is not performed by on/off control of the heater circuit as in the past, but is performed by power control based on voltage changes using a triax, so the range of temperature fluctuation is small. As a result, the inside of the furnace can be maintained at a stable temperature for a long time. In addition, a triple safety circuit has been incorporated into the heater-related circuit, so it is extremely safe to maintain heat for long periods of time without an operator, without causing abnormal temperatures. In addition, by dispersing the clay in the drawer and taking out the required number of pieces, the opening of the furnace can be made smaller to reduce fluctuations in the temperature inside the furnace when taking out the clay, and the synergistic effect of these results in stable heat retention with extremely little temperature fluctuation. became possible.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of the clay oven of the present invention, FIG. 2 is a plan view of the clay oven, and FIG. 3 is a control circuit diagram. 1...Furnace body, 3...Drawer, 4...Syrotskov fan, 5...Heater, 6...Temperature sensor, 7...
Temperature indicating controller, 8...Triack.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) A box-shaped furnace body that has a drawer with air circulation holes arranged almost evenly on the bottom and can keep the inside warm, and a fan that circulates the air inside the furnace body. , a heater that increases the air temperature inside the furnace body, a temperature sensor that detects the temperature inside the furnace body and outputs a signal, a triax that controls heating power of the heater, and a detected temperature and setting of the temperature sensor. a temperature controller that compares the temperature with the temperature and inputs the result to the triax; a first-stage safety circuit that prevents the heater power supply circuit from closing when the fan drive circuit is open; and a first stage safety circuit that prevents the heater power supply circuit from closing when the fan drive circuit is open; A clay oven characterized by comprising a next-stage safety circuit that opens the circuit. (2) The clay oven according to claim 1, wherein the fan drive circuit includes a timer circuit. (3) The clay oven according to claim 1 or 2, wherein the next-stage safety circuit comprises a thermostat and a temperature fuse.