JPH0423903B2 - - Google Patents

Abstract

PURPOSE:To eliminate readjusting because of the variation of a substance to be welded and pressure and enhance working efficiency by sensing a contacting position of a tool horn and the substance to be welded by means of the variation of transferring speed of the tool horn and starting a supersonic oscillator. CONSTITUTION:Electric signals are received at a receptor of a pulse generator 1 by transferring a transferring section by means of an air cylinder, and every time said electric signals are varied, they are turned into pulses. The slower the transferring speed of the transferring section is, the longer then intervals of said pulses are. At a converting section 2, the intervals between pulses in proportion to the intervals of pulses received at the pulse generator 1 are obtained. At a setting section 3, a comparison time sufficiently longer than an interval passing time corresponding to the normal transferring speed of the transferring section is set beforehand. Said comparison hour is compared with the interval passing time at a comparison section 4, and when the interval passing hours are equivalent to or more than the comparison hours, a contact position signal is issued to start electric mechanical vibration converter.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a device for detecting the starting position of ultrasonic vibration in an ultrasonic welding machine for plastics, etc.

[Conventional technology]

The ultrasonic welding machine is equipped with a tool horn connected to an ultrasonic oscillator and a pressure device that moves the tool horn to pressurize the object to be welded.While pressing the welding surface of the object with the tool horn, we apply ultrasonic vibrations to the welding surface of the object. It is used for welding plastics together, inserting metal into plastics, caulking metal plates to plastics, etc.

The timing to start ultrasonic vibration is as follows: (1) start vibration before the tool horn contacts the object to be welded and apply pressure while vibrating; (2) method where the tool horn and object to be welded come into contact. There are two methods: (3) starting vibration at the same time as contact is made, and (3) starting vibration after applying sufficient pressure after a delay of 0.3 to 0.5 seconds.
Select one of the methods depending on the shape, material, finish, etc. of the object to be welded. Generally, methods (2) or (3) are widely used because they allow accurate welding.

In order to start ultrasonic vibration using method (2) or (3) above, a pressure device detects the approach or contact between the moving tool horn and the workpiece, and a signal is generated to activate the ultrasonic oscillator. A device is required to activate it. Conventionally, as the ultrasonic oscillator starting device, a mechanical switch such as a limit switch or a pressure switch that operates the mechanical switch using a change in pressure has been used.

However, it is extremely difficult to mechanically operate the switch at the contact position where the tool horn contacts the welded object, and requires delicate adjustment of the activation device such as the switch. Therefore, the starting device of the ultrasonic oscillator must be readjusted every time the object to be welded is changed or the stroke or pressure of the pressurizing device is changed, which is very complicated.

[Problem that the invention seeks to solve]

SUMMARY OF THE INVENTION An object of the present invention is to provide an ultrasonic oscillator starting device for an ultrasonic welding machine that does not require readjustment every time the object to be welded is changed or the stroke of the pressurizing device or the pressurizing force is changed. .

[Means for solving problems]

The ultrasonic oscillator starting device of the present invention includes a support part fixed to a workbench, a cylinder fixed to the support part,
This is used for an ultrasonic welding machine that has a moving part that is movably supported by a support part so that the tool horn can be moved toward and away from the workbench by a cylinder, and has a tool horn attached to it; one of the support part and the moving part, or A pulse generator is attached to both and generates electric pulses at a speed proportional to the moving speed of the moving part, and the electric pulses generated by the pulse generator are input and the pulse interval is converted into time width or moving speed of the moving part. a conversion section, a setting section for presetting a comparison time or comparison speed, and a time width or moving speed inputted from the conversion section and compared with the comparison time or comparison speed set in advance in the setting section; and a comparison section that starts the oscillation circuit of the ultrasonic oscillator when the time width or moving speed becomes larger than the comparison time or smaller than the comparison speed.

The pulse generator generally includes a transmission type or reflection type photointerrupter 6 in which a photodiode light source 7 and a light receiver 8 are integrated as shown in FIG. 3a, and a transmission type or reflection type photointerrupter 6 as shown in FIG. The multiple slits 10 of the slit plate 9 have the same width as the width 1 ₁ of the multiple slits 10 that transmit light and the width 1 ₂ of the blocking portion 11 between the slits 10. They are combined so as to pass between the light receivers 8, and as shown in FIG. 4, one is fixed to the movable part 17 of the pressure device to which the tool horn 12 is fixed, and the other is fixed to the support part 16 of the pressure device. . If dust-proof or moisture-proof measures are required, use a rotary encoder that integrates the light source, receiver, and circular slit plate fixed to the rotating shaft into a sealed structure, and if high precision is required, use an optical encoder. Use a linear encoder with a magnetic or magnetic mechanism.

[Example] Fig. 4 shows a specific example of an ultrasonic welding machine equipped with an ultrasonic oscillator starting device of the present invention.
A support part 16 is fixed to a column 15 fixed perpendicular to the air cylinder 4, and the support part 16 is provided with an air cylinder 13, a solenoid valve 20 of the air cylinder 13, and a stroke adjustment screw 19 of a moving part 17. Further, a moving part 17 is movably supported by the support part 16 so as to be able to move the tool horn 12 toward and away from the workbench 14 by means of the air cylinder 13.
7 an electromechanical vibration transducer 18 and a tool horn 12;
is installed. An electromechanical vibration transducer converts electrical energy from an ultrasonic oscillator, either built into the workbench or separate, into mechanical vibration energy and transmits it to the tool horn. The movement stroke of the moving part 17 and the tool horn 12 varies depending on the shape of the welded object, etc., but is generally 30 to 50 mm, and can be adjusted with a stroke adjustment screw 19.

As shown in FIG. 1, the ultrasonic oscillator starting device includes a pulse generator 1 that is attached to one or both of the support section 16 and the moving section 17 and generates electric pulses at a speed proportional to the moving speed of the moving section 17; A converting section 2 inputs the electric pulses generated by the generator 1 and converts the pulse interval into a time width, a setting section 3 sets the comparison time in advance, and a setting section 3 inputs the time width from the converter 2. The ultrasonic oscillator is provided with a comparison section 4 that compares it with a preset comparison time and starts the oscillation circuit of the ultrasonic oscillator when the time width input from the conversion section 2 becomes larger than the comparison time.

The pulse generator 1 has a transmission type photointerrupter 6 shown in FIG. 3a shown in the support part 16 and a slit plate 9 shown in FIG. 3b attached to the moving part 17 in combination as described above. 9 is the board thickness
A large number of slits with a width of 1 ₁ = 1 mm on a 1.5 mm steel plate.
0 and a large number of blocking portions 11 having a width of 1 ₂ =1 mm are provided alternately.

[Effect]

A flowchart of the operation of the ultrasonic oscillator starting device of the present invention is shown in FIG. 1, and a timing table of the operation of FIG. 1 and the operation of the welding machine is shown in FIG.

The solenoid valve 20 is switched to the pressurizing direction by the start signal, and the tool horn 1 is activated by the air cylinder 13.
The moving unit 17 to which 2 is fixed begins to descend, and at the same time, the ultrasonic oscillator starting device is switched on to start detection.

In the light receiver 8 of the pulse generator 1, as the moving part 17 is moved by the air cylinder 13, the light from the light source 7 is not bright while it passes through the slit 10 of the slit plate 9 as shown in FIG. While the portion th and the light are blocked by the slit plate 9, the dark portion tl is sensed. As soon as the tool horn 12 comes into contact with the workpiece to be welded on the workbench 14, the moving speed slows down, so the time for the light to pass through the slit 10 or the blocking part 11 of the slit plate 9 becomes longer, and the light receiver 8 is in the bright area or The time for sensing the dark area becomes longer (in Fig. 2, the dark area tl' is sensed).

Electrical signals corresponding to such bright areas and dark areas are obtained by the light receiving unit 8, and each time this electric signal changes (at each boundary between the bright area and the dark area), it is converted into a pulse as shown in Fig. 2, and a pulse is generated. Generated from vessel 1. The interval between these pulses becomes longer as the moving speed of the moving section 17 is slower.

In the converter 2, a time width between pulses proportional to the interval between pulses obtained by the pulse generator 1 is determined. For example, if the widths of the unit section slit 10 and the blocking section 11 are made the same (1 ₁ = 1 ₂ ) as in the embodiment, when the moving speed is constant as shown in FIG. A constant section passing time t ₁ is obtained corresponding to the time width, and when the tool horn 12 comes into contact with the welded object and the moving speed slows down, a long section passing time t ₁ is obtained corresponding to the long inter-pulse time width tl. ′ is required.

In the setting section 3, a comparison time _t2 that is sufficiently longer (for example, approximately 2 to 15 times) longer than the section passing time _t1 corresponding to the normal moving speed of the moving section 17 is set in advance.

This comparison time t ₂ is compared with _the section passing time t ₁ in the comparator ₄ , and as shown in FIG. is emitted to activate the electromechanical vibration transducer 18. For example, the comparator 4 resets the delay circuit that emits an output signal when the comparison time t ₂ has elapsed every interval passing time t ₁ , so that t ₁ <t ₂
In the range of , the touch position signal is not generated due to the reset, and the touch position signal can be generated when t ₁ ≧t ₂ .

As shown in FIG. 2, the oscillation timer 5 of the electromechanical vibration transducer 18 is activated by the contact position signal from the comparison section 4, and ultrasonic vibration is transmitted to the tool horn 12 pressurizing the welded object. Welding begins. The oscillation timer 5 normally stops the vibration in about 0.5 to 1 second, and the welding is completed, and at the same time, as shown in FIG. 2, the cooling timer 5' is turned on to cool down for about 0.3 to 0.5 seconds while pressurized. When the cooling timer 5' is turned off and cooling is completed, the solenoid valve 20 is switched to the upward direction, the pressurization by the air cylinder 13 is released, and the moving part 17 and tool horn 12 rise to their original positions and complete one stroke. (2-3 seconds) is completed.

As shown in FIG. 2, even while the oscillation timer 5 and the cooling timer 5' are operating, the tool horn 12 pressurizes the welded object by the air cylinder 13, so that the tool horn 12 pressurizes the welded object during welding. There is a sinking. However, even if the tool horn 12 moves due to sinking, as shown in FIG. Problems such as signals being output are eliminated. Alternatively, a storage section may be provided to store the contact position signal, and the ultrasonic oscillation may be continued by retaining the memory until the tool horn 12 returns to its original position and one stroke is completed. good.

The practical moving speed of the tool horn in an ultrasonic welding machine is 10 to 25 cm/sec, and in this case, for example, as in the above embodiment, the distance between the slit 10 and the blocking part 11 is equal (l ₁ = 1 ₂ ). If the slit plate 9 is used, the section passing time _t1 will be 4 to 10 msec, and the comparison time _t2 may be set to 20 to 50 msec.

In the case of a rotary encoder, the number of pulses per revolution is 200, the number of spur gears is 70, and the rack gear is
When using a combination of 125 ridges per 200 mm, the section passing time t ₁ is 4.5 to 11 msec at the same moving speed as above.
Therefore, the comparison time _t2 may be similarly set to 20 to 50 msec.

The above example shows a case where the pulse interval in the pulse generator is converted into a time width and compared with the comparison time, but the pulse interval is converted into a moving speed and compared with a preset comparison speed A contact position signal may be generated when the moving speed becomes smaller than the comparison speed.

〔Effect of the invention〕

According to the present invention, the contact position between the tool horn and the object to be welded is detected based on a change in the moving speed of the tool horn, and the ultrasonic oscillator is activated. There is no need to repeat adjustments every time the pressure is changed, and work efficiency can be dramatically improved.

[Brief explanation of drawings]

FIG. 1 is a flowchart of the operation of the ultrasonic oscillator starting device of the present invention. Figure 2 is a waveform diagram showing the timing of the operation of the starting device in Figure 1 and the operation of the welding machine. Each shows the operation of the tool horn. FIG. 3a is a perspective view of a photointerrupter used in the apparatus of the present invention, and FIG. 3b is a front view of the slit plate. FIG. 4 is a side view of an ultrasonic welding machine equipped with the device of the present invention. DESCRIPTION OF SYMBOLS 1... Pulse generator, 2... Conversion section, 3... Setting section, 4... Comparison section, 6... Photo interrupter, 7... Light source, 8... Light receiving section, 9... Slit plate, 10 ...slit, 11...blocking part, 12...
... tool horn, 16 ... support section, 17 ... moving section, 18 ... electromechanical vibration transducer.

Claims (1)

[Claims] 1 A superstructure having a support part fixed to a workbench, a cylinder fixed to the support part, and a movable part movably supported by the support part and attached with a tool horn so that the tool horn can be brought into contact with and separated from the workbench by the cylinder. In a sonic welding machine: A pulse generator is attached to one or both of the supporting part and the moving part and generates electric pulses at a speed proportional to the moving speed of the moving part, and the electric pulses generated by the pulse generator are input to generate pulses. A conversion section that converts an interval into a time width or a moving speed of the moving section, a setting section that presets a comparison time or a comparison speed, and a comparison section that inputs the time width or moving speed from the conversion section and presets it in the setting section. a comparison unit that compares the time or the comparison speed and starts the oscillation circuit of the ultrasonic oscillator when the time width or movement speed input from the conversion unit becomes larger than the comparison time or smaller than the comparison speed; Ultrasonic oscillator starting device for welding machine.