JP7298098B2 - Ultrasonic vibrator drive circuit and ultrasonic welding device - Google Patents

Description

TECHNICAL FIELD The present invention relates to an ultrasonic vibrator drive circuit and an ultrasonic welding device, and more particularly, to an ultrasonic vibrator that prevents damage to each component by suppressing the vibrator current when the ultrasonic vibrator starts to oscillate. The present invention relates to a child drive circuit and an ultrasonic welding device.

The ultrasonic vibrator is mounted, for example, in an ultrasonic welding apparatus that welds the parts to be welded by applying ultrasonic vibration and weight to the parts to be welded.

2. Description of the Related Art Conventionally, the one disclosed in Patent Document 1 is known as an ultrasonic welding apparatus equipped with this type of ultrasonic vibrator.

In Patent Document 1, a workpiece including a part to be welded is placed on an anvil, a weight is applied to the part to be welded of the workpiece, and ultrasonic vibration is applied from an ultrasonic vibrator through a horn to perform welding. A configuration for welding target sites is described.

Here, the horn is driven by an ultrasonic vibrator. Conventionally, as shown in FIG. , a pair of IGBTs (insulated gate bipolar transistors) 703 a and 703 b and a matching circuit 704 .

In the ultrasonic transducer driving circuit 700 shown in FIG. 4, an oscillation signal A and an oscillation signal B obtained by inverting the oscillation signal are output from a Colpitts oscillation circuit 701 . , the pulse transformer 702 outputs a gate signal GA and a gate signal GB synchronized with the oscillation signal A and the oscillation signal B, respectively.

The gate signal GA output from the pulse transformer 702 is used to turn on/off the IGBT 703a, and the gate signal GB is used to turn on/off the IGBT 703b. Here, the matching circuit 704 performs matching control between the ON/OFF frequencies of the IGBTs 703 a and 703 b and the oscillation frequency of the ultrasonic transducer 60 .

In the conventional ultrasonic transducer driving circuit 700 having such a configuration, a gate signal GA synchronized with the oscillation signal A is output from one output terminal of the pulse transformer 702 as shown in FIG. From the other output terminal of the pulse transformer 702, as shown in FIG. 5B, a gate signal GB obtained by inverting the gate signal GA synchronized with the oscillation signal B is output. , and the IGBT 703b are alternately turned on and off, and the oscillation of the ultrasonic transducer 60 is started.

Since the conventional ultrasonic transducer drive circuit shown in FIG. At the start of the oscillation of 60, as shown in FIG. 5(C), a very large transducer current Ivc flows, and as a result, the power devices, transducers, and the like that constitute this ultrasonic transducer drive circuit 700 may be damaged. was there.

JP 2018-1176 A

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an ultrasonic vibrator drive circuit and an ultrasonic welding apparatus that prevent damage to each component by suppressing the vibrator current at the start of oscillation of the ultrasonic vibrator. and

In order to achieve the above object, the first aspect of the invention provides an ultrasonic transducer drive circuit for driving an ultrasonic transducer by means of outputs of a pair of switching elements alternately switched by a gate signal, wherein the ultrasonic transducer is a pulse generation circuit for generating a pulse signal that is controlled to gradually increase the on-time for a certain period of time at the start of oscillation of the vibrator, and then maintains the constant on-time; and the pulse signal generated by the pulse generation circuit. and a switching drive circuit for outputting the gate signal in synchronism with the ultrasonic transducer to suppress an excessive transducer current that flows when the oscillation of the ultrasonic transducer starts .

According to a second aspect of the invention, in the first aspect of the invention, the ultrasonic vibrator is mounted on an ultrasonic welding machine and driven intermittently during welding of the workpiece by the ultrasonic welding machine. Characterized by

The invention of claim 3 is the invention of claim 1 or 2, wherein the pair of switching elements comprises a pair of insulated gate bipolar transistors having their emitters and collectors connected to each other, and the switching drive circuit comprises: It is characterized by comprising a gate driver that outputs two gate signals for alternately turning on a pair of insulated gate type bipolar transistors.

The invention according to claim 4 is the invention according to any one of claims 1 to 3, wherein the pulse generation circuit is controlled so that the ON time gradually increases at the start of oscillation of the ultrasonic transducer. It is characterized by comprising an FPGA that generates a pulse signal.

According to a fifth aspect of the invention, there is provided an ultrasonic welding apparatus that applies a weight to a portion to be welded and applies ultrasonic vibration generated from an ultrasonic vibrator to the portion to be welded to weld the portion to be welded, An ultrasonic vibrator drive circuit for driving the ultrasonic vibrator by output of a pair of switching elements alternately switched by a gate signal, wherein the ultrasonic vibrator drive circuit operates when the ultrasonic vibrator starts to oscillate. a pulse generation circuit for generating a pulse signal in which the on-time is controlled to gradually increase for a certain period of time and then maintains the constant on-time; and the gate in synchronization with the pulse signal generated from the pulse generation circuit. and a switching drive circuit that outputs a signal , and suppresses an excessive oscillator current that flows when the ultrasonic oscillator starts to oscillate .

According to a sixth aspect of the invention, in the fifth aspect of the invention, the pair of switching elements comprises a pair of insulated gate bipolar transistors having their emitters and collectors connected to each other, and the switching drive circuit comprises a pair of It is characterized by comprising a gate driver that outputs two gate signals for alternately turning on an insulated gate type bipolar transistor.

The invention of claim 7 is the invention of claim 5 or 6, wherein the pulse generation circuit generates a pulse signal controlled to gradually increase the ON time at the start of oscillation of the ultrasonic transducer. It is characterized by being made of FPGA.

According to the present invention, there is provided an ultrasonic vibrator driving circuit for driving an ultrasonic vibrator by means of outputs of a pair of switching elements alternately switched by a gate signal, and , a pulse generation circuit for generating a pulse signal whose ON time is controlled to gradually increase and then maintains a constant ON time; and outputting the gate signal in synchronization with the pulse signal generated from the pulse generation circuit. and a switching drive circuit that suppresses an excessive oscillator current that flows when the ultrasonic oscillator starts to oscillate. It is possible to provide an ultrasonic vibrator drive circuit and an ultrasonic welding device that prevent damage to equipment.

FIG. 1 is a side view schematically showing an embodiment of an ultrasonic welding apparatus to which an ultrasonic vibrator drive circuit according to the present invention is applied. FIG. 2 is a circuit diagram showing an example of an ultrasonic transducer drive circuit according to the present invention. FIG. 3 is a waveform diagram showing waveforms of signals in each part of the ultrasonic transducer drive circuit shown in FIG. FIG. 4 is a circuit diagram showing a conventional ultrasonic transducer drive circuit. FIG. 5 is a waveform diagram showing waveforms of signals in each part of the ultrasonic transducer drive circuit shown in FIG.

Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the attached drawings.

FIG. 1 is a schematic diagram of a first embodiment of an ultrasonic welding apparatus according to the present invention.

In FIG. 1, an ultrasonic welding apparatus 100 according to the present invention places a workpiece 30 including a welding target portion on an anvil 20 fixed to a pedestal 10, and applies a pressure device (not shown) to the welding target portion of the workpiece 30. By applying a weight and applying ultrasonic vibration from the tip 41 of the horn 40, the work 31 and the work 32 are welded at the welding target portion of the work 30, that is, the surface where the work 31 and the work 32 are in contact. be.

Horn 40 is connected to ultrasonic transducer 60 via cone 50 , and ultrasonic transducer 60 is driven by ultrasonic transducer drive circuit 70 .

Here, the ultrasonic vibration applied from the tip of the horn 40 to the welding target portion 33 of the workpiece 30 is vibration in the vertical direction Y perpendicular to the welding target portion 33 . Ultrasonic welding using ultrasonic vibration in the vertical direction Y is suitable for melt welding of resin, for example.

A portion including the horn 40, the cone 50, and the ultrasonic transducer 60 is held by an ultrasonic transducer holder 61 attached to the cone 50, and the load applied to the workpiece 30 from a pressure device (not shown) is applied by the ultrasonic transducer. This is done via the holder 61 .

The ultrasonic welding apparatus 100 configured as described above intermittently drives the ultrasonic vibrator 60 , that is, controls the on/off of the ultrasonic vibrator 60 to sequentially weld the workpieces 30 .

FIG. 2 is a circuit diagram showing an example of the ultrasonic vibrator drive circuit 70 of the ultrasonic welding apparatus 100 shown in FIG.

The ultrasonic transducer drive circuit 70 shown in FIG. It consists of

Here, the pulse generation circuit 71 generates a pulse signal PA controlled so that the ON time gradually increases until the oscillation of the ultrasonic transducer 60 stabilizes when the oscillation of the ultrasonic transducer 60 starts. , PB. This pulse generating circuit 71 can be configured from, for example, an FPGA (field programmable gate array).

The pulse signals PA and PB output from the pulse generation circuit 71 are applied to the switching drive circuit 72, and the switching drive circuit 72 outputs the gate signal GA and the gate signal GB for controlling the on/off of the IGBTs 73a and 73b. . Here, the switching drive circuit 72 can be composed of, for example, a MOSFET type gate driver. Other configurations are the same as those of the conventional ultrasonic transducer drive circuit 700 shown in FIG.

That is, in the ultrasonic transducer driving circuit 70 according to the present invention shown in FIG. 2, instead of the Colpitts oscillation circuit 701 used in the conventional ultrasonic transducer driving circuit 700 shown in FIG. A generator circuit 71 is employed, and instead of the pulse transformer 702, a high-speed controllable MOSFET type switching drive circuit 72 is employed.

Here, the oscillation signal A and the oscillation signal B output from the Colpitts oscillation circuit 701 used in the conventional ultrasonic transducer driving circuit 700 always have a constant on-duty. Since the pulse generation circuit 71 employed in 70 is configured using an FPGA or the like, the ON time is gradually increased at the start of oscillation of the ultrasonic transducer 60 until the oscillation of the ultrasonic transducer 60 stabilizes. It is possible to generate a pulse signal controlled to increase the on-duty gradually.

The switching drive circuit 72 is controlled by the output pulse signals PA and PB of the pulse generation circuit 71. Since the switching drive circuit 72 can be composed of a MOSFET type gate driver, high-speed control is possible. be.

FIG. 3 is a waveform diagram showing waveforms of signals in each part of the ultrasonic transducer driving circuit 70 shown in FIG.

In FIG. 3, FIGS. 3A and 3B show gate signals GA and GB for controlling on/off of the IGBT 73a and IGBT 73b of the ultrasonic transducer drive circuit 70. FIG. C) shows the transducer current Ivc of the ultrasonic transducer drive circuit 70. FIG.

Now, in FIG. 3, a period T indicates a period until the oscillation of the ultrasonic transducer 60 stabilizes when the oscillation of the ultrasonic transducer 60 is started. In the ultrasonic transducer drive circuit 70 of the present invention, during this period T, the pulse generation circuit 71 generates pulse signals PA and PB controlled to gradually increase the ON time, and the switching drive circuit 72 , outputs gate signals GA and GB synchronized with the pulse signals PA and PB, as shown in FIGS. 3(A) and 3(B).

At this time, the transducer current Ivc of this ultrasonic transducer driving circuit 70 shown in FIG. As a result, an excessive vibrator current Ivc does not flow as in the conventional ultrasonic vibrator drive circuit 700 shown in FIG. It is possible to prevent damage to various devices such as children.

In particular, when the ultrasonic vibrator drive circuit 70 of the present invention is employed in an ultrasonic welding device, this type of ultrasonic welding device intermittently drives the ultrasonic vibrator 60 to oscillate the ultrasonic vibrator 60. Since the stop is repeated, it is possible to greatly reduce the damage to each component of the ultrasonic welding apparatus caused by excessive oscillator current at the start of oscillation of the ultrasonic oscillator 60 of the ultrasonic welding apparatus.

As described above, in the present invention, instead of the Colpitts oscillator circuit 701, the gate pulse generator circuit 71 made up of FPGA or the like is adopted. can be suppressed, thereby preventing damage to various devices such as power devices and vibrators.

Further, in the present invention, instead of the pulse transformer 702, a MOSFET type switching drive circuit 72 capable of high-speed control is adopted. The time until the oscillation of the element 60 stabilizes is also shortened, and when it is used in an ultrasonic welding device, quick welding becomes possible.

In addition, in the above-described embodiment, the configuration using IGBT as the switching element is shown, but a power MOSFET (power MOS field effect transistor) can also be used for the same configuration.

The present invention is not limited to the above-described embodiments, and many modifications are possible within the scope of the technical idea of the present invention by means of ordinary creativity of those skilled in the art. For example, the present invention can be applied not only to ultrasonic welding devices but also to various devices using ultrasonic vibrators.

DESCRIPTION OF SYMBOLS 10... Pedestal 20... Anvil 30... Work 40... Horn 50... Cone 60... Ultrasonic vibrator 61... Ultrasonic vibrator holder 70... Ultrasonic vibrator drive circuit 71... Pulse generation circuit 72... Switching drive circuit 73a, 73b... IGBT (insulated gate bipolar transistor)
74 Matching circuit 700 Ultrasonic transducer drive circuit 701 Colpitts oscillation circuit 702 Pulse transformer 703a, 70b IGBT (insulated gate bipolar transistor)
704 ... Matching circuit

Claims (7)

An ultrasonic transducer driving circuit for driving an ultrasonic transducer by output of a pair of switching elements alternately switched by a gate signal,
a pulse generation circuit for generating a pulse signal controlled to gradually increase the on-time for a certain period of time when the ultrasonic transducer starts oscillating, and then maintaining a constant on-time;
a switching drive circuit that outputs the gate signal in synchronization with the pulse signal generated from the pulse generation circuit;
and suppressing an excessive oscillator current that flows when the ultrasonic oscillator starts to oscillate . The ultrasonic transducer is
Installed in an ultrasonic welding machine,
2. The ultrasonic vibrator drive circuit according to claim 1, wherein the ultrasonic vibrator driving circuit is intermittently driven during welding of a workpiece by the ultrasonic welding machine. The pair of switching elements are
Consists of a pair of insulated gate bipolar transistors with their emitters and collectors connected to each other,
The switching drive circuit
3. The ultrasonic transducer drive circuit according to claim 1, further comprising a gate driver that outputs two gate signals for alternately turning on the pair of insulated gate bipolar transistors. The pulse generator circuit
4. The ultrasonic vibration according to any one of claims 1 to 3, comprising an FPGA that generates a pulse signal controlled to gradually increase the ON time at the start of oscillation of the ultrasonic vibrator. child drive circuit. An ultrasonic welding apparatus that applies a weight to a welding target portion and applies ultrasonic vibration generated from an ultrasonic vibrator to the welding target portion to weld the welding target portion,
an ultrasonic transducer driving circuit for driving the ultrasonic transducer by output of a pair of switching elements alternately switched by a gate signal;
The ultrasonic transducer drive circuit includes:
a pulse generation circuit for generating a pulse signal controlled to gradually increase the on-time for a certain period of time when the ultrasonic transducer starts oscillating, and then maintaining a constant on-time;
a switching drive circuit that outputs the gate signal in synchronization with the pulse signal generated from the pulse generation circuit;
and suppressing an excessive oscillator current that flows when the ultrasonic oscillator starts to oscillate . The pair of switching elements are
Consists of a pair of insulated gate bipolar transistors with their emitters and collectors connected to each other,
The switching drive circuit
6. The ultrasonic welding apparatus according to claim 5, further comprising a gate driver that outputs two gate signals for alternately turning on the pair of insulated gate bipolar transistors. The pulse generator circuit
7. The ultrasonic welding apparatus according to claim 5, comprising an FPGA that generates a pulse signal controlled to gradually increase the ON time when the ultrasonic vibrator starts oscillating.

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