JPS6160552B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an operation stagnation circuit in an induction heating device that continuously feeds an object to be heated to an induction heating coil by a conveying device such as a pinch roller. If the rotation detecting pulse generation proximity switch installed near the drive motor fails and the feeding of the object to be heated is stagnant, there is a possibility that the operation stagnation circuit will not operate and the object to be heated may be melted. Therefore, when the rotation drop detector detects that the pulse generation proximity switch for rotation detection of the drive motor does not output pulses at a certain period, the supply of heating power to the induction heating coil is interrupted, and the heated The present invention aims to provide an induction heating device that prevents accidents such as melting of objects.

FIG. 1 shows the operation stagnation circuit of a conventional induction heating device of this type, in which 1 is a drive motor, and 2 is rotationally driven by this drive motor 1 to feed an object to be heated 16 into an induction heating coil 15. pinch roller,
3 is rotatably pressed against the outer surface of the object to be heated 16 by its own weight or spring force, and the object to be heated 1
A free roller 6 rotates as the drive motor 1 advances; 4 a first pulse generator cam plate that rotates in synchronization with the drive motor 1; and 5 a second pulse generator cam plate that rotates in synchronization with the free roller 3. a cam plate; 6 is a first pulse generating proximity switch that detects the rotation of the cam plate 4 for the first pulse generator; 7 is a second pulse that detects the rotation of the cam plate 5 for the second pulse generator; Proximity switch for generation, 8 is this second
A differential element 9 that converts the output waveform of the pulse generating proximity switch 7 into an instantaneous pulse counts by the output of the first pulse generating proximity switch 6, and is reset by the output of the differential element 8,
10 is a control unit for the drive motor 1; 11 is a variable resistor for adjusting the speed of the drive motor 1; 13 is a control unit for controlling the drive motor 1; It is a contact that closes by a signal.

Since the operation stagnation circuit in the conventional induction heating device is configured as described above, the rotation of the pinch roller 2 driven by the drive motor 1 causes the first pulse generator cam plate 4 to rotate.
When the object to be heated 16 advances toward the induction heating coil 15, the free roller 3 and the second pulse generator cam plate 5 follow this and rotate. These rotations are detected by the first and second pulse generation proximity switches 6 and 7, and the pulses from the first pulse generation proximity switch 6 are counted by the counter 9. , and the pulse from the other second pulse generating proximity switch 7 passes through the differential element 8 and becomes a reset input for the counter 9. The preset value of this counter 9 is determined by setting the ratio of the number of pulses of the first proximity switch 6 for pulse generation to the number of pulses of the second proximity switch 7 for pulse generation to n:1 (n+α (α is a margin). ,
In the normal state of conveyance of the object to be heated 16, the first
The counter 9 starts counting in response to the pulse from the second pulse generating proximity switch 6, but as the object to be heated advances, the output of the second pulse generating proximity switch 7 is converted into an instantaneous waveform by the differentiating element 8. It is converted into a pulse and the counter 9 is reset.

Therefore, when the heated object 16 is being normally fed into the induction coil 15, this counter 9
will never reach the preset value and no alarm output will be output. If the heated object 16 stagnates due to some malfunction even though the drive motor 1, the pinch roller 2, or the first pulse generator cam plate 4 is being driven, the counter 9 reset input is activated. Since the pulses have stopped, this counter 9 reaches the preset value, and the heating power source is immediately cut off by the alarm output to prevent the object to be heated 16 from melting.

However, as shown in the operation explanatory diagram of FIG. 2, if the first pulse generation proximity switch 6 fails and does not output a pulse even though the drive motor 1 is rotating, the counter Since no pulse is input to the set input of the counter 9, even if the object to be heated 16 stagnates, the counter 9 will not reach the preset value, and processing operations such as turning off the heating power by the alarm output will not be performed, and the object to be heated will not reach the preset value. Thing 1
6 may be melted.

This invention has been made with attention to this point, and for example, the first pulse generation proximity switch 6
It is an object of the present invention to provide an operation stagnation circuit for an induction heating device that will not cause the heated object 16 to melt even if the induction heating device malfunctions.

That is, FIG. 3 shows one embodiment of the present invention, and since the same reference numerals and components are the same as those of the conventional device (FIG. 1) described above, the explanation thereof will be omitted.

12 is a lower limit speed setting variable resistor for setting the lower limit speed of the drive motor 1 in the control unit 10;
Reference numeral 14 denotes a rotation reduction detector which detects that the pulses of the first pulse generation proximity switch 6 are no longer output after a certain period and outputs an alarm output, and an example of its operation is shown in FIG.

Reference numeral 17 denotes a control power source for this rotation reduction detector 14.

In other words, as shown in FIGS. 3 and 5, when the contact 13 is closed by an operation command, the rotation drop detector receives the output of the control power source 17 and charges it according to a predetermined time constant. It discharges when it receives a pulse signal transmitted by the generation proximity switch, and generates an alarm output when the charging voltage reaches a preset value.

As described above, the operation stagnation circuit in the induction heating device of the present invention includes a variable resistor 12 for setting the lower limit speed to prevent the drive motor 1 from rotating below a certain level.
If the first pulse generation proximity switch 6 fails and pulses are not generated at or above the constant frequency set by the lower limit speed setting variable resistor 12, the operation shown in FIG. 4 is performed. As shown in the explanatory diagram, this is detected by the rotation reduction detector 14, and the heating power source is immediately cut off by the alarm output, thereby achieving an excellent effect of preventing the object to be heated 16 from melting. It is something that you have.

[Brief explanation of the drawing]

Fig. 1 is a stagnation circuit diagram of a conventional induction heating device, Fig. 2 is an explanatory diagram of its operation, Fig. 3 is a stagnation circuit diagram of the present invention, Fig. 4 is an explanatory diagram of its operation, and Fig. 5 is a rotation diagram. It is an explanatory diagram of operation of a drop detector. In the drawing, 1 is a drive motor, 2 is a pinch roller,
4 is a cam plate for the pulse generator, 6 is a proximity switch for first pulse generation, 8 is a differential element, 9 is a counter, 10 is a drive motor control unit, 11 is a variable resistor for speed adjustment, 12 is a lower limit speed setting 14 is a rotation drop detector, and 15 is an induction heating coil. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A control unit for controlling the speed of a drive motor that feeds the object to be heated into an induction heating coil, a variable resistor for setting a lower limit speed for setting a lower limit speed of the drive motor in this control unit, connected to the drive motor, A pulse generation cam plate that rotates in accordance with the rotation of the drive motor, and a pulse generation proximity switch that is provided opposite to the pulse generation cam plate and generates a pulse signal in accordance with the rotation of the pulse generation cam plate. , when the drive motor is driven, is charged at a predetermined time constant by the output from the control power source, and
An induction heating device characterized by comprising a rotation drop detector which generates an alarm output when the charging voltage exceeds a set value by being discharged by a pulse signal generated by the pulse generating proximity switch.