JPH02299193A - Inductive heater - Google Patents

Abstract

PURPOSE:To sequentially forge and process each pellet with appropriate temperature maintained by a method wherein each pellet is transferred to forging process at a pitch faster than that of the forging process and controlled so that the transfer is suspended if it is resident for a specific period or longer. CONSTITUTION:A plurality of pellets 11 are sequentially transferred to a forging apparatus 5 with sending cycle time TH while being heated by a heating coil 12 to be forged at operating cycle time TP wherein the control is performed by a CPU 20. A signal VR of a speed setting unit 6 controls the sending cycle time TH so that it is a little shorter than that of the operating cycle time TP. The heated pellets 11 are transferred by a conveyer 15 to enter forging process after waiting time TW. The waiting time TW increases as the time passes and when it is a specific value or larger sending is suspended for a specified period. Thus pellets at appropriate temperature can be supplied without delay at the time point required by the forging apparatus.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an induction heating device that heats a forged material called a billet to a predetermined temperature and synchronously sends it to a forging device.
In particular, the present invention relates to an induction heating device that stabilizes the quality of forged products by improving synchronization compatibility with forging equipment.

[Prior Art] In order to perform forging, an induction heating device called a forging press heats a billet to a predetermined temperature and synchronously sends the billet to a forging device. In addition, this type of induction heating device is capable of operating multiple units in parallel in order to flexibly respond to production formats, as described in, for example, Japanese Patent Publication No. 51-15254 and Japanese Patent Publication No. 51-36491. , billet heat treatment capacity can be multiplied by an integral number and sent out synchronously.

Fig. 5 is a block diagram showing the functional configuration of one conventional induction heating device. This is a sending detector that outputs a signal H.

(2) is a control device for the induction heating device, which takes the time difference of the sending cycle signal H consisting of a pulse waveform and calculates the sending interval (
a timer T that calculates the sending cycle time) T8, a reference signal generator (21) that outputs a reference signal To of M T N during the sending cycle, a reference signal To and the sending cycle time T,
and a regulator (23) that outputs a speed increase signal U or a deceleration signal as a speed command according to the comparison result from the comparator (22).

(3) The electric motor (4) responds to the speed increase signal U or deceleration signal
) is a speed control box that increases or decelerates the rotational speed of a motor, and is composed of, for example, a commercially available general-purpose inverter intended for variable speed control of a standard three-phase induction motor.

FIG. 6 is a block diagram specifically showing the vicinity of the feeding mechanism of the induction heating device, and (1a) and (1b) are the light emitter and light receiver that constitute the sending detector (1) for outputting the sending cycle signal H. (5) is a forging device equipped with a conveying function and a chucking function operated in synchronization with an induction heating device, (11)
) is heated in an induction heating device and a forging device (5)
The billet (12) is forged inside the heating coil inside the induction heating device.

(13) is a pinch roller constituting a feeding mechanism for the billet (11) within the heating coil (12), and is driven by the electric motor (4) in FIG.

(14) is a feed conveyor placed on the feed side of the heating coil (12), and (15) is a feed conveyor placed on the feed side of the heating coil (12), which are driven by a drive source (not shown). It is now possible to do so. (16a) and (18b) are a light projector and a light receiver for outputting a detection signal B of the billet (11) at a chucking point in the forging device (5).

As described above, the induction heating device includes a heating coil (12) that heats the billet (11) to a predetermined temperature, and a heating coil (12) that heats the billet (11) to a predetermined temperature.
), that is, a pinch roller (13) having a variable speed conveyance function, and a billet (11) feed-out detector (1). (11) is sequentially fed, and a forged product with a complicated shape is obtained by forging several shots. Therefore, it is important to make the delivery cycle time T9 of the billet (11) almost equal to the operation cycle time Tp of the forging device (5) and to supply the billet (11) to the forging device (5) at an appropriate temperature without delay. This is important for quality control.

Next, the operation of the conventional induction heating apparatus shown in FIGS. 5 and 6 will be explained.

The billet (11) conveyed by the feeding conveyor (14) is sequentially fed into the heating coil (12) by the pinch roller (13) and heated to a predetermined temperature, and then heated at a predetermined delivery cycle time T11. Extrusion and delivery conveyor (15)
It is transported by and supplied to the forging device (5). At this time, the delivery detector (1) detects the billet (11) delivered from the heating coil (12) and inputs a pulsed delivery cycle signal H to the control device (2).

A comparator (22) in the control device (2) compares the sending cycle time T based on the sending cycle signal H with the reference signal To, and inputs the comparison result to the regulator (23). The regulator (23) outputs a speed-up signal U when the delivery cycle times T and I are greater than the reference signal TO, and outputs a deceleration signal when the delivery cycle time Tll is smaller than the reference signal To.

When the speed increase signal U is input, the speed control box (3) increases the rotation speed of the electric motor (4) and turns the pinch roller (1).
By increasing the rotation speed of step 3) and increasing the moving speed of the billet (11), the delivery cycle time Tn is made to be a constant line and matched with the reference signal To.

Conversely, when the deceleration signal is input, the billet (1
By decreasing the moving speed of 1), the delivery cycle time T is increased to match the reference signal To.

The forging device (5) detects the billet (11) transported to the chucking point by the delivery conveyor (15) through detectors (16a) and (16b) consisting of a light emitter and a light receiver.
After confirming the presence of billet 11),
The forging operation is carried out by conveying or chucking. At this time, in the control device (2), the sending cycle time TI
and the reference signal To, so billet (1
The delivery cycle of 1) is synchronized with the operation cycle of the forging device (5), and the billet (11) is reliably placed at the chucking point during the forging operation.

However, the adjustment range of the sending cycle time T is limited to the reference signal To.
Furthermore, since the reference signal TO is an internal signal of the control device (2), the delivery cycle of the billet (11) may not always be the same as that of the forging device (5) due to various condition changes. ) may not match the operating cycle.

FIG. 7 is a timing chart showing the operation cycle and billet detection operation of the forging device (5), where P is an operation cycle signal for actually transporting or chucking the billet (11), and T is a normally constant signal. Forging interval (operating cycle time), B is billet at chucking point (11)
This is a detection signal for confirming the presence or absence of.

In Fig. 7, period (a) is a normal operating state in which the billet (11) reaches the chucking point of the forging device (5) at an appropriate delivery timing, and period (b) is a normal operating state in which the billet (11) reaches the chucking point of the forging device (5). Period (c) shows a state in which the billet (11) reaches the forging device (5) late.

During the period (b) when the billet (11) is delivered early, the waiting time T before the chucking operation increases, and conversely, during the period when the billet (11) is delivered late (
In c), after the forging device (5) performs one blank shot (see P'), the billet (11) is chucked in the next shot.

As stated in Japanese Patent Publication No. 51-15254, this phenomenon is caused not only by structural and instantaneous causes such as slipping of the pinch roller (13), but also by movement due to wear of the pinch roller (13). Speed reduction and forging equipment (5)
Effective preventive measures have not been implemented because of various causes such as changes in aging conditions caused by changes in the operating cycle time of the die-forged products. Since the material temperature of the billet (11) varies at the moment when the billet (11) is forged, the more complex the forged shape of the billet (11), the more likely it will be affected by the attributes of the detailed metal structure, resulting in a defective product.

For example, in the case of a billet (11) with a diameter of 100 wheels,
If the initial temperature is 1250"C, there is data that the temperature of the billet (11) after 40 seconds is 1150"C due to the relationship between the material temperature and the standing time. Then, the time T (1°) required to lower the temperature by 1°C is T (1°) = 40 [seconds] / (1250 ['C] - 115
0["C]) = 0.4[sec/゛C], where the temperature of 30°C is based on the general heating temperature tolerance (±30"C) required for induction heating equipment. If only a decrease is acceptable, the allowable standing time T (30°) of the billet (11) under the above condition is T (30''
'') = 0.4 [sec μC] x 30 ['C] = 12 [sec] Therefore, considering the conveyance time by the delivery conveyor (15), the maximum allowable waiting time T is about several seconds. becomes.

Therefore, if the forging device (5) runs dry due to fluctuations in the billet (11) supply status, or if the waiting time TV increases and there is significant heat dissipation, the billet (11) during forging may
) The temperature of the billet (11) decreases and the quality of the forged product cannot be stabilized.
The smaller the mass (heat capacity) of the To prevent this, conventionally the billet processing amount (
A so-called bypass operation is performed in which the billet (11) is pulled out each time stagnation occurs on the forging device W (5) side by setting the feed amount (output amount) slightly larger.

[Problems to be Solved by the Invention] As described above, the conventional induction heating device does not take various condition changes into consideration and the reference signal To generated within the control device (2)
Based on this, the billet (11) delivery cycle time TII is adjusted and the pinch roller (13) feed speed is controlled to be constant, so if conditions change, the billet (11) delivery cycle There were problems in that the operation cycle of the forging device (5) could not be reliably matched, resulting in deterioration in the quality of the forged product and a large amount of wasted material due to bypass during retention.

This invention was made to solve the above-mentioned problems, and it is possible to reliably produce a billet at the appropriate temperature without delay by waiting within a predetermined range immediately before the forging device requests operation. The purpose is to obtain an induction heating device that can be supplied.

[Means for Solving the Problems] The induction heating device according to the present invention calculates the delivery time from the operation timing of the forging device to the next billet delivery timing based on the delivery cycle signal and the operation cycle signal of the forging device. , a control device is provided that stops the feeding mechanism for a predetermined period of time when the feeding time falls below a permissible value.

[Operation] In this invention, the delivery time as a reference signal for delivery timing control is calculated from the operation cycle signal and the delivery cycle signal, and when the delivery time becomes less than the allowable value and goes out of the target range, the delivery time is calculated from the operation cycle signal and the delivery cycle signal. The timing is adjusted by stopping the feeding mechanism of the induction heating device for a certain amount of time to ensure that the billet is fed at the time when the forging device requests operation.

Therefore, the speed of the feed mechanism should be set so that the delivery cycle time is slightly shorter than the operating cycle time.
Precise adjustment of the delivery timing means that when the delivery time falls below a predetermined value, that is, when the billet waiting time at the chucking point exceeds a predetermined allowable limit, the next billet will have an appropriate waiting time. This is done by stopping the feeding mechanism for a predetermined period of time to ensure that the next billet is stopped in a timely manner and held in the induction heating device. It is controlled within a certain range to match the operating cycle of the device.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings. 1st
The figure is a block diagram showing the functional configuration of an embodiment of the present invention, where (2^) corresponds to the control device (2), and (1) corresponds to the control device (2).
), (3) and (4) are the same as described above. or,
The configuration of the induction heating device is as shown in FIG.

(6) is a speed setter that inputs a set speed signal VR of a predetermined voltage level to the control device (2^).

The control device (2^) includes a CPU (20) having a calculation function, a memory function, etc., and a sending cycle signal H from the sending detector (1) and an operation cycle signal P from the forging device (5). DIU for input to U (20)
(digital input crab knit) (24) and setting speed signal V
An AD conversion unit (25) for converting R into a digital signal and inputting it to the CPU (20);
DA conversion unit (26) for converting the speed command C from 20) into an analog signal and outputting it to the speed control box (3).
), the main body of which is a commercially available sequencer, and a programmable control device that performs numerical calculations according to the program written in the CPU (20) and operates external actuators, etc. in sequence. . Also, CPU (20) and CP
The memory in U (20) is connected to each unit (24)-(26) via a common bus.

FIG. 3 is a timing chart showing the operation of an embodiment of the present invention, where Tc is the time required to convey the billet (11) by the delivery conveyor (15), and Tpt+ is the operation based on the chucking point. This is the delivery time from the timing to the next billet delivery timing.

Next, the operation of the embodiment of the present invention shown in FIG. 1 will be described with reference to the flow chart in FIG. 2, the timing chart in FIG. 3, and the configuration diagram in FIG. 6.

First, the rotational speed of the pinch roller (13) is set so that the feeding cycle of the billet (11) is slightly faster than the operation cycle of the 'a3fi device (5), using the set speed signal VR from the speed setting device (6). (Step S)
l).

As a result, during the normal operation period (a), the set speed signal VR from the speed setter (6) is taken into the CPU (20) via the AD conversion unit (25), and is further input into the DA conversion unit ( 26) through the speed control box (3
), and the pinch roller (13) receives the set speed signal V
Rotating at a constant speed according to R, the billet (11) passes through the heating coil (12) at a constant speed and is delivered at a constant pitch. The sending cycle time T at this time.

The operation cycle time T is almost the same as T, which is slightly shorter than the operation cycle time T. Therefore, it is ensured that the billet (11) always reaches the chucking point when the forging device (5) is requested to operate.

In such a stable operating state, the operation cycle time TP, the delivery cycle time T, and the required conveyance time Tc are stable and take constant values.

Moreover, the required time Te for conveyance of the delivery conveyor (15) is measured in advance, so that the waiting time Tw is set to the minimum allowable value T.
It is set to be equal to or longer than w x + w (for example, 1 second).

However, the operation cycle time TP and the delivery cycle time T
8 do not match perfectly and T p > T H , the waiting time T increases as time passes as shown in Figure 3.
, gradually increases.

Therefore, every time the billet (11) is sent out, the sequencer program in the CPU (20) calculates the timing of sending out 1iJ T p- based on the chucking point based on the operation cycle signal P and the sending cycle signal H. is calculated (step S2).

That is, T c + T w is determined from the difference in the rising timing of the sending cycle signal H and the operation cycle signal P, and further, from the difference between this value and the operation cycle time T, T pH = T p (T C + Tw) −
Find ■.

Here, if the maximum allowable value T IIIAX of the waiting time T is 5 seconds and the minimum allowable value T II N I +1 is 1 second, then the waiting time Tw will always be a value within the range of 1 second to 5 seconds. must be controlled.

Therefore, the sequencer program in the CPU (20) determines whether the sending time TPII is smaller than the allowable value T, □ when the waiting time T in the formula is the maximum allowable value Tw, AX. (Step S3).

Then, T PH< T pHs= T p (, T C+
T IINAX), it is determined that the waiting time T in the next operation cycle is greater than the allowable maximum value (=5 seconds), and ΔT' N = T IIMAX T @HI I
+=4 [seconds] Speed command C for a predetermined time ΔT (=4 seconds) obtained from
is stopped (step S4), and the process returns to step S2.

As a result, the pinch roller (13) stops during the early period (b) of the delivery timing, so the closing time during the delivery cycle is T, +ΔT, and the waiting time T is the minimum allowable value T.
II M+. (1 second) Returns to the value above.

At this time, the timing at which the pinch roller (13) stops is after the previous billet (11) has been sent out, and the next billet (11) will be waiting in the heating coil (12) in a state with little cooling. Therefore, the temperature drop during stoppage can be ignored.

Although the operating time of the CPU (20) varies depending on the amount of programs, it is possible to easily increase the speed by reducing the scanning time to several tens of logical seconds or less.

In addition, the speed control box (3) consisting of an inverter has sufficient ability to reduce the output within 0.1 seconds by setting the voltage level of the speed command C to 0 [V] as shown in Figure 3. Therefore, even if the inertia of the pinch roller (13) and the like are taken into consideration, it is possible to control the distance of 1 m at a stop in units of about 0.5 seconds.

On the other hand, in step S3, if it is determined that T 1111≧TP□, the waiting time T is the maximum allowable value T,□
Since it is the following, it is determined that the operating state is normal and the process returns to step S2.

In this way, each time the delivery time 'rpt+ becomes equal to or less than the allowable value T pN
The billet (11) at an appropriate temperature within a waiting time T of 1 to 5 seconds can be reliably supplied to the chucking point without delay at the time when the billet (11) requests operation. Therefore,
Waste material due to bypass during delay is eliminated, wasteful heating energy consumption is eliminated, and temperature variations due to cooling of the billet (11) are reduced, so the quality of the forged product is stabilized.

In addition, since the sending time T□, which is the control standard for the waiting time T, is calculated based on the operation cycle signal P, even if the operation cycle time T changes over time, the waiting time T is always kept within a predetermined range. The billets (11) can be reliably delivered synchronously by adjusting the value within the range. However, as is clear from equation (2), the delivery time TPII is calculated using the sum of the previous transport time Tc and the waiting time T, so it is not calculated during the first billet delivery, but is calculated using the sum of the previous billet delivery time Tc and the waiting time T. It is calculated every time the billet is sent out thereafter.

Furthermore, if the difference between the operation cycle time T and the delivery cycle time T is made smaller to approximate them, the number of feed stops will be reduced, which will improve the wear of the pinch roller (13) and maintain accuracy. It can be realized without any problems.

In addition, in the above embodiment, a case was shown in which a synchronous sending function was added to one induction heating device, but as shown in FIG. 4, the control devices (2^) of multiple induction heating devices are operated in parallel. It can be fully applied even when other accessories are added.

In Fig. 4, (7) is a condition setting device with a built-in storage device, etc., which includes a part number setting device (7a) for setting the part number of the billet (11), and a part number setting device (7a) for setting the part number of the billet (11), and the feed speed V and heating temperature of the billet (11). It is equipped with a display ()b) that displays the set value of the corresponding output voltage (■), and a switch (7c) that selects the number of operating control devices (2^). (8) is the control device
^) is a voltage setting device for setting the output voltage ■, and (9) is a heating power source for driving the heating coil (12) with the output voltage ■.

(10) is a master control device located above the control device (2^), and is connected to each of multiple (in this case, two) control devices (2^) via a data link bus (30). At the same time, an operation cycle signal P of the forging device (5) and selection setting information Q of the condition setting device (7) are input.

In Figure 4, the main control bag! Before starting the operation in (10), the operator sets various conditions using the condition setting bag W1 (7). That is, when the product number (type) of the billet (11) is selected using the product number setting device (7a), the feed speed V, output voltage V, etc. registered in advance in the storage device in the condition setting device (7) are set according to the product number. The conditions are input as selection setting information Q to the master control device (10). Similarly, when the control device (2^) to be operated is selected by the switch (7c), an operation indicating the operation of only the first unit of the two units, both of the first unit and the second unit, or only the second unit is displayed. The number of machines is input as selection setting information Q to the master control device (10).

Next, when the main control device (10) starts the operation,
Each control device (2^) imports the selection setting information Q into its respective CPU (20) via the bus (30), judges the information content, and performs a predetermined operation. It is possible to centrally and easily change the number of units in operation, such as single unit operation, parallel operation of unit 1 and unit 2, etc.

For example, when operating two control devices (2A) in parallel,
The induction heating device belonging to each control device (2^) performs the same control as described above using a signal obtained by dividing the operating cycle signal P in FIG. This enables synchronous transmission during parallel operation.

In this case, the output voltage ■ of the heating power source (9) is
Since the output voltage is supplied through the DA conversion unit (not shown) in the billet (11), the output voltage ■ during the period when the billet (11) is stopped at a timely time and is on standby can be easily reduced by changing the program. can. Therefore, the heating coil (12)
It is possible to prevent excessive temperature rise due to stop heating within the billet (11), and the billet (11) can be delivered at an ideal constant temperature.

In addition, if the required opening Tc for billet transport in each induction heating device differs due to differences in equipment arrangement, the control device (2
^) to manual mode and set the condition setting device (7c).
), and the actual induction heating device and forging device (5)
By operating the program and setting the program's calculation constants based on the individual measured data, reliable synchronous transmission is possible.

During the operation mode based on the selection setting information Q from the condition setting device (7), the main control device (10) to the control device (2^)
Since the feed speed ■ and output voltage ■ are given to the controller, the setting signals from each setting device (6) and (8) are
) is not used.

However, when operating without using the condition setting device (7) in order to collect data for registering the part number of a new billet (11), each setting device (6) and It is necessary to set the output voltage V. Therefore,
Switch to manual mode and set each setting device (6) and (8).
), input the set speed signal VR corresponding to the feed rate ■ and the output voltage ■ corresponding to the heating temperature to the control device (2^), and when the appropriate values are determined by actual operation measurements,
These are registered as selection setting information Q in the storage device of the condition setting device C).

[Effects of the Invention] As described above, according to the present invention, the delivery time from the operation timing of the forging device to the next billet delivery timing is calculated based on the delivery cycle signal and the operation cycle signal of the forging device, and the delivery time is calculated based on the delivery cycle signal and the operation cycle signal of the forging device. A control device is provided that stops the feeding mechanism for a predetermined period of time when the amount of time becomes less than the allowable value. By stopping the feed mechanism when the target range is exceeded, the feed timing can be finely adjusted and the waiting time can be controlled within a predetermined range, so that the billet at the appropriate temperature can be delivered without delay at the time required by the forging equipment. This has the effect of providing an induction heating device that can be supplied to the chucking point.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the functional configuration of an embodiment of the present invention, FIGS. 2 and 3 are flowcharts and timing charts for explaining the operation of FIG. 1, and FIG. 4 is a block diagram showing the functional configuration of an embodiment of the present invention. FIG. 5 is a block diagram showing the functional configuration of another embodiment. FIG. 5 is a block diagram showing the functional configuration of a conventional induction heating device. FIG. 6 is a configuration diagram showing the vicinity of the feeding mechanism of a general induction heating device. The figure is a timing chart diagram for explaining the operation of the conventional device. <1)... Delivery detector (2^)... Control device (5)... Forging device (11)... Billet (12)... Heating coil (13)... Pinch roller ( Feed II! 4 horizontal) H...
- Sending cycle signal T8... Sending cycle time P...
- Operation cycle signal Tp...operation cycle time TpH
...Transmission time TP□...Tolerance value ΔT11・
. . Predetermined time Note that in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Scope of Claims] An induction heating device for sequentially heating a plurality of billets to a predetermined temperature and sending them to a forging device, comprising: a heating coil that heats the billets; and a heating coil for heating the billets, and the forging device for feeding the billets at a predetermined delivery cycle time. a feed mechanism that sends out the billet to the feeder; a feed detector that detects the feed timing of the billet and outputs a feed cycle signal; and a feed detector that detects the feed timing of the billet and outputs a feed cycle signal; An induction heating apparatus comprising: a control device that calculates a delivery time until the next billet delivery timing, and stops the feeding mechanism for a predetermined time when the delivery time becomes less than an allowable value.