JPH0539825Y2 - - Google Patents

Description

[Detailed description of the invention] [Summary] By detecting the solder liquid level with an optical fiber sensor that moves up and down with the work holder, stable dipping is possible regardless of the amount of molten solder in the solder bath.

[Industrial application field]

The present invention relates to a dip soldering device that performs dip soldering while detecting the solder liquid level.

[Conventional technology]

In a dip soldering process in which a workpiece is immersed in a molten solder liquid level in a solder bath, changes in the solder liquid level (for example, a decrease due to consumption) affect the lowering position of the workpiece. For this reason, conventionally, for example, a jet solder bath as shown in FIG. 3 is used to keep the solder liquid level constant.

In FIG. 3, 1 is a solder bath, 2 is heated molten solder, 3 is a pump, and 4 is a spout cylinder.
When the pump 3 is rotated, the solder 2 is ejected upward from the ejection tube 4, but since the pressure is always kept constant, the ejected liquid level 5 of the solder 2 is always a certain distance a from the opening of the ejection tube 4. formed upwards.
Therefore, by lowering the workpiece toward the spouted liquid level 5, stable dipping can be repeatedly performed regardless of changes in the amount of solder in the tank.

[The problem that the idea aims to solve]

However, the method shown in FIG. 3 has the disadvantage that the structure inside the tank is complicated and large, and it is also expensive.

By optically detecting the solder liquid level, the present invention enables stable dipping at all times regardless of the height of the solder liquid level.

[Means to solve the problem]

Figure 1 is a diagram of the principle of the present invention, where 1 is a solder bath, 2
21 is the molten solder, 21 is its liquid level, and 6 is a reflective optical fiber sensor. This sensor 6 has a stop 61 in the center and a flexible optical fiber 62 behind it.
connected to the detection circuit. This detection circuit includes a light emitting element, a light receiving element, an amplifier, and the like. Further, the front end 64 of the optical fiber 63, which is difficult to deform, serves as a liquid level detection section.

Incidentally, if the intensity of the light emitted from the optical fiber 6 becomes high at a position shifted from the optical axis, the fiber 6 is tilted by that amount (α=20 to 30°) and fixed.

[Effect]

The sensor 6 detects the reflected light level when the distance between the liquid level detection section 64 and the solder liquid level 21 reaches a constant value l, and issues a stop signal. This reflected light is transmitted to sensor 6
is the scattered reflection light from the liquid surface 21 of the emitted light. Since the distance l is a relative value that does not depend on the absolute height of the liquid level 21, if the sensor 6 is raised and lowered together with the work holder, the workpiece to be soldered can always be kept at a constant depth on the liquid level 21. It has the advantage of being able to date travel.

〔Example〕

FIG. 2 is a configuration diagram showing an embodiment of the present invention.
8 is a work to be soldered, 8 is a work holder that holds the work, 9 is a belt that raises and lowers the holder, and 10 is a pulley driven by a motor.

The optical fiber sensor 6 is fixed to a holder 8 and moves up and down together with the holder. When the workpiece 7 is immersed to an appropriate depth from the liquid level 21, the sensor 6 detects a reflected light level corresponding to the distance l and outputs a signal to stop the motor. This stop signal is the liquid level 21
Therefore, even if the liquid level 21 gradually decreases due to repeated dipping, the workpiece 7 can always be dipped to a constant depth from the liquid level 21.

According to actual measurements, it has been confirmed that the holder 8 can be stopped with an accuracy of ±0.15 mm.

It is also possible to fix the sensor 6 in a fixed position and control the stop position of the holder 8 by detecting the level of the liquid level 21, but in this method, the output of the sensor 6 is linear in response to changes in the liquid level 21. If the range of change is narrow, control accuracy may decrease. On the other hand, if the sensor 6 is moved up and down integrally with the holder 8 as in the present invention, only the relative distance l to the liquid level 21 needs to be detected with high accuracy, so the control accuracy can be increased. .

[Effect of idea]

As described above, according to the present invention, dipping can always be performed to a constant depth even if the liquid level in the dip solder bath changes. In addition, since the structure is not complicated like a jet solder tank, it can be implemented at low cost without increasing the size.

There is a method of detecting the solder liquid level using a pair of electrodes immersed in the liquid surface, but with this method, solder adheres to the tips of the electrodes, resulting in poor measurement accuracy of the liquid level height (distance between the electrode and the liquid surface). . In addition, light is emitted from one emitter, and the light reflected from the liquid surface is received by the receiver on the opposite side. When the liquid level drops, the reflected light cannot be received, so the drop in the liquid level is detected, and the solder is removed. Some devices are designed to supply solder or issue an alarm, but with these, the emitter and receiver cannot be installed close to the solder liquid surface due to heat resistance issues, resulting in poor distance measurement accuracy. This invention uses an optical fiber sensor,
Since the optical fiber has excellent heat resistance, the tip can be brought close to the solder liquid surface, and distance detection accuracy can be significantly improved. Further, since the optical fiber is flexible, it is easy to adjust the light irradiation position, and the device has a high degree of freedom and is simple in construction.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the principle of the present invention, FIG. 2 is a block diagram of an embodiment of the present invention, and FIG. 3 is a structural diagram of a conventional jet solder bath.

Claims (1)

[Scope of Claim for Utility Model Registration] A dip solder tank 1 containing molten solder 2, a work holder 8 that holds a work 7 immersed in the solder 2, and a lifting mechanism 9, 1 that raises and lowers the work holder 8.
0, and an optical fiber sensor 6 that moves up and down integrally with the work holder 8 and emits and enters light from a tip 64 of an optical fiber 63, the optical fiber sensor 6
The dip soldering apparatus is characterized in that when the tip 64 of the solder 2 approaches the liquid level of the solder 2 to a certain distance, a stop signal is output to stop the lowering by the lifting mechanisms 9 and 10.