JPS6262426B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electric heating device, and in particular to a device for induction heating of items.

The invention may be used for induction heating of a wide range of parts with welds, for example using power supplied from several power sources.

Devices for regulating induction heating for surface hardening of parts are known in this field (USSR No. 168317 inventor's certificate, classification
See C21D142). The device includes an automatically programmed temperature regulator inserted into the generator's excitation circuit and uses temperature feedback. The device is used to adjust the hardening process. Its principle elements are an operating coil connected to a regulated high-frequency power supply, a temperature detection element for detecting the temperature of a selected point on the member to be heated, and a setting element connected to a comparison unit of the regulator. The output of is connected to a regulated high frequency power supply (generator) via an amplifier and an actuator.

Devices for regulating the induction heating process are also known in the art (USSR No. 541155 Inventor's Certificate, Classification
(See G05D23/27). The above device is the first part of the automatic regulator.
It includes a temperature sensing element connected to the input and coupled to the exciter of the controlled generator, the output of which is used as a high frequency power source. The power supply output is connected to an oscillator circuit consisting of a working coil, a member and a balancing capacitor. When a power transducer is inserted into the working coil, the output of which is connected via a converter to the second input of the autoregulator, said converter consists of two untuned elements and an integrator; are arranged in parallel and their outputs are connected to an adder.

However, if a certain heating effect is required by the working coils of the above-mentioned devices in which two or more devices are arranged close to each other, the processing of large parts (e.g. to heat several areas of a large part)
The magnetic fluxes associated with the working coils interact with each other, a drawback which essentially limits the field of use of the known device. When conditions change in a heated region, a corresponding change occurs in an adjacent region, and vice versa. This is generally a limiting factor.
Furthermore, continuous oscillation is established in the power circuit of the device, operating the overvoltage protection circuit.

Other research is in induction heating devices for tempering welding (see the known Elphiae booklet published in Belgium). The device includes a temperature sensing element connected to a temperature regulator and the output of which is connected to a thyristor exciter of an alternator coupled in matching manner to a transformer via a common bus. Two working coils with balanced capacitances whose capacitances are set before excitation is applied are connected to the output of the transformer.

The device includes a temperature regulator for each working coil.
Connected to the input of each regulator is an electrical mode transducer used for the test power consumed by the temperature sensing element and the operating coil. Each temperature regulator includes a device for setting the temperature to be maintained by the regulator. A disadvantage of the known device is that it is not possible to provide uniform heating of the entire heating area of a given part, especially during partial heat treatment of large asymmetrical parts.
The disadvantage of the above is that when the working coils are placed close to each other in the same member, the above-mentioned device produces interference that prevents the desired thermal field pattern from being obtained in the working area of each working coil. . This interference is reinforced by the disturbance acting on each working coil, thereby establishing self-sustaining oscillation in the thermal mode control system.

The different characteristics of the drive motors of the device power supply reduce the overall efficiency of the device and are responsible for self-sustaining oscillations of the control system due to disturbances. It is an object of the invention to provide an apparatus for induction heating of parts which ensures uniform heating of the entire area undergoing heat treatment. That is, an object of the present invention is to increase the uniformity of local heating of a large asymmetrical member and to improve heating efficiency by reducing mutual influence of working coils.

Another object of the invention is to ensure partial heat treatment of large asymmetrical parts.

Another object of the invention is to increase the efficiency of the power supply used in the device.

Yet another object of the invention is to improve the heat treatment of welded joints of large parts.

Electrical mode comprising at least two working coils connected to independent power supplies, each with balanced capacitance, one input connected to the other input of the temperature regulator connected to the corresponding temperature sensing element Cooperative with the transducer, the temperature regulator consists of a unit for setting the ratio between the power transducer and the power of each power source according to the invention, the first input of the unit being connected to the power of the power source via a corresponding signal converter. connected to the power transducer, the other input being common to all working coils of the device and connected to the output of a temperature regulator having a device for setting the temperature maintained in the heating region of the member; The object of the present invention is to provide an apparatus for induction heating of a component in which the output of the working coil is coupled to a corresponding power source of the working coil.

Preferably, the power ratio regulator includes a power ratio setting circuit and a comparison circuit, each of which is connected via one input to a corresponding power transducer and via the other input to a corresponding output of a temperature sensor. Connected.

The invention will be described in detail on the basis of specific embodiments thereof and in conjunction with the accompanying drawings.

The component induction heating device forming the essence of the invention comprises at least two working coils and is, for example, a highly asymmetrical component 1 with a weld 2 (FIG. 1).
Designed for partial heat treatment of Depending on the radius, wall thickness and shape of the member 1 to be heated, the device comprises three working coils 3, 4, 5 (FIG. 1) or two working coils 3, 4 (FIG. 2).

According to this invention, the device has a balanced capacity of 9, 10, 1
1 and a power supply 6, 7, 8 for each operating coil 3-5 (FIG. 1) having a switch, and a temperature detection element 13,
14, 15, and electric mode transducer 1
6, 17, 18, e.g. input 1 of temperature regulator 21
9 and 20.

Furthermore, according to the invention, the device connects the power transducers 22 to 24 of each power source 6, 8 via a unit 25 for adjusting the power ratio between said power sources and a corresponding signal converter 27. ~2
4, including the input 26 of said unit connected to 4.
The input 28 of the regulator 25 is connected to all working coils 3 of the device.
It is connected to the output of the temperature regulator 21 common to 5 to 5. The output of the regulator 25 is connected to the power supplies 6-8 of the working coils 3-5. The temperature regulator designed according to the known method has only one device 29 for setting the temperature maintained in the heating region of the component 1.

Referring now to FIG. 2, a more detailed embodiment of the device with working coils 3, 4 is shown. The power ratio regulator 25 here consists of comparison elements 30, 31, corresponding power transducers 22, 23, and inputs of each element connected to the output of the temperature regulator 21. The outputs of comparison elements 30, 31 are connected to power supplies 6, 7, elements 30, 31 are connected to common control lead 33 and variable resistor 3, as well as indicator 34.
2 and are interconnected via a power ratio setting circuit that operates together with the power ratio setting circuit.

The device forming the essence of the invention operates as follows.

The operator drives the temperature setting device 29 to obtain a desired state when heating the member 1, and each operating coil 3, 4
The control lead wire 33 of the resistor 32 is set at a position where the power ratio of the resistor 32 is optimized. The distribution of the axial temperature T over the length L during a given time must conform to the distribution as shown in FIG.

After switching on the device, the temperature regulator 21 controls the regulated power supplies 6, 7 which regulate the power input to the working coils 3, 4 via the regulator 25. The component 1 is heated in a predetermined manner.

The temperature deviation in the heating area is determined by the temperature regulator 21.
Temperature detection elements 13 and 14 supply signals corresponding to two inputs 19 of the temperature sensor. The temperature regulator 21 compares a current value corresponding to the temperature with a value set by receiving a signal from the temperature setting device 29. If the temperature setting signal is larger or smaller than the current temperature at which the member 1 is heated, the temperature regulator 2
1 generates a control voltage for the power supplies 6 and 7 corresponding to its output. The control voltage affects the power supplies 6, 7 via the regulator 25. Regulator 25 redistributes the output control voltage of temperature regulator 21 through resistor 32 according to the power ratio set by comparators 30, 31 and lead 33.

In this way, a predetermined temperature T (FIG. 3) is maintained in each heating zone. The feature of such control is that it eliminates the following disadvantages of prior art induction heating devices for parts and also ensures a uniform temperature range over the entire heating area of the part. Moreover, complex temperature range patterns are obtained by setting different power ratios for each working coil using control leads 33 of resistors 32.

Transducers 16, 17, which detect the electrical parameters of the working coils 3, 4, provide commands to the inputs of the temperature regulator 21, directing the current in the working coils 3, 4. If the permissible current value is exceeded, the transducer provides a command to disconnect the working coil from the power supply 6,7.

When various disturbances act on the working coil 3, for example, the power transducer 22 detects said disturbances and provides commands to the regulator 25 via the transducer 27. This command is applied to the comparison element 30 via the input 26 and from there affects the second comparison element 31 proportionally through the resistor 32. as a result,
The output of the regulator 25 generates a control voltage that affects the power supplies 6, 7, thereby eliminating disturbances. The above disturbance is caused by operating coil 3 and operating coil 4 (in the latter case,
(depending on the position of control lead 33 of resistor 32). Such a method of eliminating existing disturbances makes it possible to eliminate self-sustaining oscillations in the heating process control of the component 1.

The present invention has the advantage of allowing a method to automatically adjust the induction heating mode according to the outputs of frequency converters with different characteristics, thereby increasing efficiency. Furthermore, it ensures a more uniform heating of the corresponding areas of the component undergoing heat treatment, and the general feature consists in improving the automatic control of the heating process by eliminating self-sustaining oscillations associated with the heat treatment and various disturbances.

[Brief explanation of the drawing]

1 is a block diagram of an apparatus for induction heating a bullet according to the invention; FIG. 2 is a block diagram of an apparatus comprising two working coils; and FIG. Shows heating temperature changes. 1... Member, 2... Welding part, 3, 4, 5... Operating coil, 6, 7, 8... Power supply, 9, 10, 11
... Balance capacity, 12 ... Switch, 13, 14,
15... Temperature detection element, 16, 17, 18...
Electric mode transducer, 19, 20... Regulator input, 21... Temperature regulator, 22, 23,
24...Power transformer, 25...Power ratio regulator, 26...Input of unit 25, 27...
Signal converter, 28...Input of unit 25, 29
... Temperature setting device, 30, 31 ... Comparison element, 32
...Variable low resistance, 33...Control lead wire of resistor 32, 34...Indicator.

Claims (1)

[Claims] 1. Includes at least two operating coils 3 to 5,
Each of these had a balanced capacitance 9-11, was connected to an independent power supply 6-8, cooperated with an electrical mode transducer 16-18, and one input was connected to a corresponding temperature sensing element 13-15. In the member induction heating device connected to the other input of the temperature regulator 21,
It includes a power transformer 25 of each power source 6-8 and a unit 25 for setting the ratio between the power sources, the first input 26 of said unit being connected to the power transformer of the power sources 6-8 via a corresponding signal converter 27. connected to the generators 22-24, a further input 28 is connected to a temperature regulator 21, which is common to all working coils 3-5 of the device and has a device 29 for maintaining the heated area of the component at a set temperature; and the output of the power ratio regulator 25 is coupled to the corresponding power source 6-8 of the working coils 3-5. 2. In the device according to the first claim, the power ratio regulator 25 includes a power ratio setting circuit and a comparison element 30, 31, each of which is connected to a corresponding power transducer 22, 23. temperature regulator 2 through the other input.
1 and connected to the corresponding output of element 3 above.
0,31 is a variable resistor 32 with a common control line 33
A device characterized in that the device is interconnected through a power ratio setting circuit cooperating with the device.