JPH08257727A - Method for heating ingot for metallic injection molded article - Google Patents

Abstract

PURPOSE: To heat a metal ingot at a prescribed temperature and to keep the temperature after heating with a few variation without worrying about the dispersion of temperature display of a radiation thermometer at a time of heating the metal ingot while measuring the temperature with the radiation thermometer. CONSTITUTION: An induction heating controlling part 50 to control an induction heating coil 42 is composed of a light detecting part and shored photoelectric signal converter 51, a target temperature program system temperature controller 52, a target temperature set value outside input system temperature controller 53, an analog memory 54, a sequencer 60, and a relay 55, and pre-testing, heating and keeping of the temperature are executed successively by switching the target temperature program system temperature controller 52 and the target temperature set value outside input system temperature controller 53 with the sequencer 60.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a method for heating an ingot of a metal injection molded body.

[0002]

2. Description of the Related Art It is important to know an accurate temperature of an ingot when heating and retaining the heat of a metal ingot in order to form a high quality metal compact. Therefore, conventionally, the temperature of an ingot heated by an induction heater or a resistance heater is measured by a radiation thermometer, the energization of the heater is controlled to raise the temperature to a predetermined temperature, and the temperature is maintained for a predetermined time. Was doing.

[0003]

However, in the radiation thermometer, since the emissivity changes depending on the shape, surface roughness, and surface condition of the ingot, the temperature display varies. On the other hand, it is possible to know the correct temperature by embedding the thermocouple directly in the ingot and measuring the temperature, but in order to carry out the subsequent crushing continuously, it is necessary to remove the thermocouple. So it was difficult to do this work.

The present invention has been made to solve the above-mentioned problems, and an object thereof is to provide a predetermined value without worrying about the variation in the temperature display of the radiation thermometer when heating the metal ingot while measuring the temperature with the radiation thermometer. The purpose is to carry out heating at temperature and subsequent heat retention with small fluctuations.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention sets the heating and heat retaining conditions of an ingot by using a thermocouple as a temperature measuring means of the ingot, and heating the ingot in a test furnace of the same type as an actual furnace. The first step in which the heating time until the temperature measured value of the thermocouple reaches the set value is set to t1 and the temperature measuring means of the ingot is a radiation thermometer, and the ingot is put in an actual furnace for heating. A second step is started in which the measured value of the radiation thermometer when the heating time reaches the time t1 is T1 and a target temperature for controlling the measured value T1 of the radiation thermometer is set to the second step. Subsequently, the third step of performing heat retention was performed.

[0006]

[Function] The time involved in heating to the set temperature is obtained by testing in advance in a test furnace using a thermocouple and a timer, and the ingot is heated to the set temperature by heating for the above time in the actual furnace, and at this time The temperature of is measured with a radiation thermometer and the temperature is maintained based on the measured value.

[0007]

Embodiments of the present invention will be described below with reference to the accompanying drawings. Here, FIG. 1 is a cross-sectional view of a main part of an injection molding apparatus to which the method for heating a metal injection molded body according to the present invention is applied.

It comprises an injection molding apparatus 1, an injection machine 3 having a screw 2 built-in, and a material supply chamber 10 for supplying a raw material to the injection machine 3. The material supply chamber 10 is introduced from top to bottom. It comprises a chamber 11 (see FIG. 2), a heating chamber 12 as an actual furnace, a warming chamber 13, and a crushed material accumulating chamber 15 equipped with a crushing cutter 21.

The crushing cutter 21 is a tip member of the crushing means 20, and includes a drive shaft 22, a free shaft 23, and a biaxial gear case 2.
4. The motor 26 is connected via the speed reducer 25.
The two-shaft gear case 24 is an output distributor having one input shaft and two output shafts, and one motor 26 is used for two crushing cutters 2.
1, 2 are rotated in opposite directions.

The greenhouse 13 is surrounded by a heat-retaining heater 31 and a heat insulating material tube 32, has a height enough to accommodate one ingot, and has a vacuum / gas pipe connected to the upper part thereof. The vacuum / gas pipe 33 is evacuated or supplied with an inert gas by switching.

The crushed material accumulating chamber 15 has a certain height and has a high level sensor 35 and a low level sensor 36 which are separated in the height direction. Reference numeral 37 in the drawing denotes a thermometer for measuring the temperature distribution in the axial direction of the injector 3.

FIG. 2 is a sectional view taken along the line AA of FIG. The heating chamber 12 is a vacuum heating container including a cylindrical ceramic holder 41, an induction heating coil 42, a magnetic shield material 43, and an outer cylinder 44, and an upper shutter 45, an ingot stopper 46, and a lower shutter are provided on an upper portion, an inner portion, and a lower portion, respectively. It is equipped with 47.

The holder 4 is provided outside the heating chamber 12.
A radiation thermometer 49 is provided which measures the temperature of the ingot W through the hole 48 bored in the radial direction 1 and outputs a signal 49a corresponding to the measured temperature. The radiation thermometer 49 is an induction heating control. It is connected to the section 50.

The induction heating control section 50 is connected to the induction heating coil 42, and a signal 49a from the radiation thermometer 49 is provided.
The energization of the induction heating coil 42 is controlled based on

FIG. 3 is a sectional view of a heating chamber as a test furnace, and the same members are designated by the same reference numerals. The heating chamber (test furnace) 70 has the same shape, the same volume, and the same material as the heating chamber (actual furnace) 12, and the heating chamber (actual furnace) 12 measures the temperature of the ingot W using the radiation thermometer 49. On the other hand, the temperature of the ingot W is measured using the thermoelectric thermometer 71 using a thermocouple. The thermoelectric thermometer 71 uses a material and a wire diameter that are not affected by induction heating.

Specifically, the glass wool 7 in the heating chamber 70
One end of the thermoelectric thermometer 71 is inserted into the ingot W through the upper opening blocked by 2, and the other end is connected to the display unit 73. Although not shown, the induction heating coil 42 is controlled by the same induction heating control unit as in the case of the actual furnace.

FIG. 4 is a block diagram showing the control system of the induction heating control section. The induction heating control unit 50
Photodetector / photoelectric signal converter (referred to as signal converter) 5
1. Target temperature programmable temperature controller (referred to as program temperature controller) 52, target temperature set value external input temperature controller (referred to as external input temperature controller) 53, analog memory 54, sequencer 60, and It consists of a relay 55.

The signal converter 51 receives the light output from the fiber radiation thermometer (radiation thermometer 49) for measuring the temperature of the ingot W through the optical fiber, and
This light is converted into an electrical signal, and this signal is used as the measurement temperature signal 5
Output as 1a.

The programmable temperature controller 52 inputs the measured temperature signal 51a as a measured value and inputs it as a measured temperature signal 5
2a to the analog memory 54. At the time of heating and heat retention in the actual furnace, this programmable temperature controller 52
Is provided with a timer (not shown) that starts timing when a heating start command signal (RUN signal) 58a is input and resets when a time t1 calculated based on a map (described later) created in advance has elapsed. It is assumed that the timer is reset in the initial state.

The programmable temperature controller 52 is
After the heating start command signal 58a is input and the time measurement is started,
The time measured by a PID adjuster or the like is compared with the heating time t1 obtained from the map, and until the heating time t1 is reached, the heating power control signal 52b is output through the heating control means 62 such as a relay. When the heating of the induction heating coil 42 is controlled and the heating time t1 is reached,
The temperature rise time elapsed signal 52c is output.

The analog memory 54 is composed of, for example, an A / D converter, a digital memory and a D / A converter, and when the temperature rise time elapsed signal 52c is input, the measured temperature signal 52a at that time is stored as the target temperature T1. Then
This is output as the measurement value signal 54a.

The external input type temperature controller 53 compares the measured temperature signal 51a and the measured value signal 54a with a PID controller or the like, calculates the correction amount, and controls the heating control means 62 to reach the target temperature T1. The heating power control signal 53a is output to control the energization of the induction heating coil 42. Further, the external input type temperature controller 53 controls the heating power control means 62 by the heating power control signal 53a so as to stop the energization of the induction heating coil 42 when the stop command signal 59a is input.

Sequencer 60 is a test furnace (during map creation)
And a sequence operation according to the actual furnace (at the time of heating and heat retention), the temperature setting value switching signal input circuit 56, the relay switching circuit 57, the heating start command circuit 5
8 and a heat retention time management circuit 59.

The temperature setting value switching signal input circuit 56 outputs a switching command signal 56a when the temperature rising time elapsed signal 52c is input.

The relay switching circuit 57 receives the heating start command signal 58c (described later) or the switching command signal 56a, and the programmable temperature controller 52.
An energization command signal 57a for switching between the external input type temperature controller 53 and the external input type temperature controller 53 is output to the relay 55.

The heating start command circuit 58 outputs a heating start command signal 58a and a heating start command signal 58c when the ingot heating start switch 61 is turned on for heating, and causes the programmable temperature controller 52 to operate as a heating force control means. Connect to 62. When the heating start command signal 58b for keeping the temperature is output, the heating start signal 58c is output to connect the external input type temperature controller 53 to the heating force control means 62 and the heating start command signal 58d is output. Output to the heat retention time management circuit 59.

The heat retention time management circuit 59 uses the heating start signal 5
A timer (not shown) is provided to start timing when 8d is input and to reset when a preset time (for example, 3 hours) has elapsed. When this time has elapsed, the heat retention time management circuit 59 outputs a stop command signal 59a to the external input type temperature controller 53.

Next, the above-mentioned map creation and heating /
The heat retention operation will be described. FIG. 5 is a flowchart when creating a map in the preliminary test. Here, S1 to S9 indicate each step of the sequence operation.

The above map shows the heating chamber (test furnace) of the above configuration.
It shows the relationship of the ingot weight with respect to the heating time until the ingot is heated to the set temperature, which was created based on the measurement in 1., and is created in the test furnace before the heating and heat retention in the actual furnace. If necessary, FIG. 3 and FIG.
Shall be referred to.

When setting the temperature rising time in the test furnace, the weight of the ingot W is first measured (S1). The heating switch is turned on to energize the induction heating coil 42 and the ingot W
To start heating (S2).

When the temperature rise is started, the measurement of the time until the target set temperature is reached is started using, for example, a stopwatch or the like (S3). At the same time, the thermoelectric thermometer 71 starts measuring the temperature of the ingot W (S4), and the display unit 7
When the display of 3 reaches the target set temperature (S5),
The time measurement is stopped (S6), the induction heating coil 42 is de-energized, and the heating of the ingot W is stopped (S7). The time measured in step S6 is set as the heating time t1.

FIG. 6 shows an example of a map prepared in the above preliminary test.
It shows the case of heating up to ℃. Here, the horizontal axis represents the ingot weight (unit: gram), and the vertical axis represents the heating time (unit: second).

FIG. 7 is a flowchart of heating and heat retention in an actual furnace. Here, S10 to S20 indicate each step of the sequence operation. Note that FIG. 3 and FIG. 4 will be referred to as necessary.

First, in order to perform heating and heat retention in the actual furnace, the ingot heating start switch 61 is turned on, and the energization command signal 57a is output from the relay switching circuit 57 based on the heating start command signal 58c of the heating start command circuit 58. Then, the relay 55 is driven to connect the programmable temperature controller 52 to the heating control means 62 (S10).

When the heating start command signal 58a is input from the heating start command circuit 58, the programmable temperature controller 52 outputs the measured temperature signal 52a corresponding to the temperature of the ingot W measured by the radiation thermometer 49 to the analog memory 54. At the same time, the heating power control signal 52b is output to energize the induction heating coil 42 to start heating the ingot W (S1).
1).

At the same time, the programmable temperature controller 52
When the timer starts counting, the heating time t1 obtained from the map is compared, and when the heating time is reached (S12), the temperature rising time elapsed signal 52c is output to the analog memory 54 as a measurement value output fixed command signal, The measured temperature signal 52a is stored in the analog memory 54 as the measured value T1 (S1
3).

The stored measured temperature signal 52a is input to the external input type temperature controller 53 as a measured value signal 54a (S14).

The temperature rise time elapsed signal 52c is simultaneously output from the external input type temperature controller 53 and the temperature set value switching signal input circuit 5.
6 is input to the relay 5 via the relay switching circuit 57.
5 is driven to connect the external input type temperature controller 53 to the heating control means 62 (S15).

The external input type temperature controller 53 outputs the heating power control signal 53a to the heating control means 62 to energize the induction heating coil 42, and starts the heat retention of the ingot W with the measured value T1 as the target temperature. S16).

At the same time as the input of the start signal 58d, the timer of the heat retention time management circuit 59 starts clocking, and when the ingot W is replaced (S18) after a predetermined time (S17), the ingot W of the ingot W is replaced. Measure the weight (S
19) If the weight of the previous ingot W is the same, the process returns to the beginning of this flowchart, and if it is different, the process returns to step 2 (S20), and the same steps as above are repeated.

When the ingot W is not replaced, the stop command signal 59a is output to end the heating (heat retention) of the ingot, that is, the apparatus is stopped.

[0042]

Since the present invention has the above-mentioned structure, it has the following effects. According to a first aspect of the present invention, the heating and heat retaining conditions of the ingot are thermocouples as the temperature measuring means of the ingot, the ingot is put into a test furnace of the same type as the actual furnace to start heating, and the temperature measurement value of the thermocouple is a set value. The first step in which the heating time until reaching t1 is t1 and the temperature measuring means of the ingot is a radiation thermometer, the ingot is placed in an actual furnace to start heating, and when the heating time reaches the time t1 A second step in which the measurement value of the radiation thermometer is T1 and a third step in which heat retention is carried out subsequent to the second step as a target temperature for controlling the measurement value T1 of the radiation thermometer.

Therefore, in the actual furnace, the temperature can be accurately raised to the set temperature and can be maintained as in the case where the thermocouple is used. Therefore, it is possible to reduce variations in temperature during heating and heat retention, and Since it is possible to improve the quality of the molded body and it does not take time and effort to remove the thermocouple,
Heating and heat retention can be performed in a continuous process, which improves the productivity of the metal molded body.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part of an injection molding apparatus to which a method for heating a metal injection molded body according to the present invention is applied.

FIG. 2 is a sectional view taken along the line AA of FIG.

FIG. 3 is a sectional view of a heating chamber as a test furnace.

FIG. 4 is a block configuration diagram illustrating a control system of an induction heating control unit.

FIG. 5: Flow chart for map creation in preliminary test

FIG. 6 An example of a map created in a preliminary test

[Fig. 7] Flow chart of heating and heat retention in an actual furnace

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Injection molding apparatus, 12, 70 ... Heating chamber, 41 ... Ceramic holder, 42 ... Induction heating coil, 43 ... Magnetic shield material, 44 ... Outer cylinder, 48 ... Hole, 49 ... Radiation thermometer, 50
Induction heating control unit 51 Signal conversion unit 52 Program temperature controller 53 External input temperature controller 54
Analog memory, 55 ... Relay, 56 ... Temperature setting value switching signal input circuit, 57 ... Relay switching circuit, 58 ... Heating start command circuit, 59 ... Insulation time management circuit, 60 ... Sequencer, 61 ... Ingot heating start switch, 71 ...
Thermoelectric thermometer, 72 ... Glass wool, 73 ... Display section.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical display location G01J 5/02 G01J 5/02 K G01K 7/02 G01K 7/02 (72) Inventor Norimasa Hamazoe 1-10-1 Shin-Sayama, Sayama-shi, Saitama Honda Engineering Co., Ltd.

Claims (1)

[Claims] 1. A heating method for heating an ingot while measuring the temperature with a radiation thermometer, crushing the ingot, feeding the ingot to a screw of an injection molding machine, kneading and injecting with the screw to injection-mold a metal injection-molded body. In the method, the heating and heat retaining conditions of the ingot, the temperature measuring means of the ingot is a thermocouple, the ingot is put into a test furnace of the same type as the actual furnace to start heating, and the temperature measured value of the thermocouple is set to a set value. The first heating time is t1
Step, and a radiation thermometer is used as the temperature measuring means of the ingot, the ingot is put into an actual furnace to start heating, and the heating time is the time t.
The second which makes the measured value of the radiation thermometer when it reaches 1 the second
A method for heating an ingot for a metal injection-molded body, comprising: a step; and a third step of performing heat retention following the second step as a target temperature for controlling the measured value T1 of the radiation thermometer.