JPH04300072A - Cream solder discharge device - Google Patents

Abstract

PURPOSE:To always maintain the constant discharge quantity without being influenced by a partial viscosity fluctuation of cream solder contained in a syringe. CONSTITUTION:The device is provided with a syringe 16 in which cream solder 19 is contained, and a hydraulic cylinder 10 connected by a holding metallic fixture 18 for holding the syringe 16, and by a means for supplying hydraulic pressure for controlling pressure so as to become a roughly constant flow rate into the hydraulic cylinder 10, a piston 14 provided in the cylinder 10 and a piston rod 15 connected to the piston press a piston 17 in the syringe 16, and the cream solder 19 is discharged by a constant discharge quantity into the syringe 16. According to this constitution, the cream solder can be applied uniformly onto a printed board.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cream solder discharging device used to supply cream solder onto a printed circuit board when parts are soldered onto the printed circuit board.

0002

2. Description of the Related Art Conventionally, as shown in FIG. 3, this type of cream solder dispensing device applies air pressure to an air chamber 34 through a hose connected to an adapter 33 to apply cream solder 32 placed in a syringe 31. This air pressure pushes the piston 35, and the cream solder 32 is discharged from the discharge port 36 according to its viscosity due to the pressure of the piston 35.

0003

[Problems to be Solved by the Invention] Such conventional cream solder dispensing devices have the advantage of being able to discharge cream solder with a simple configuration, but due to local fluctuations in the viscosity of the cream solder, it is difficult to always maintain a stable discharge amount. The problem was that it was difficult to maintain.

[0004] The present invention solves the above problem, and an object thereof is to provide a cream solder discharging device that can always maintain a stable discharge amount.

[0005]

[Means for Solving the Problems] In order to solve the above problems, the present invention uses incompressible oil instead of pressing the piston with a constant force using compressible air pressure as in the past. A piston inside the hydraulic cylinder is moved while restricting the amount of oil flowing into the hydraulic cylinder using a flow rate restriction orifice, and a piston rod connected to the hydraulic piston pushes the piston inside the syringe, reducing the local viscosity of the cream solder. Even if there is a fluctuation, the large hydraulic piston force that overcomes this fluctuation reliably pushes the syringe piston to ensure stable discharge.

[0006]

[Operation] In the conventional structure in which a constant force is applied to the piston in the syringe using air pressure, if the viscosity of the cream solder fluctuates or the discharge port becomes clogged, it becomes difficult to discharge and the discharge amount decreases. Further, when cream solder having a partially low viscosity is discharged, it becomes easier to discharge and the discharge amount suddenly increases. As described above, conventionally it has been difficult to maintain a stable discharge amount over a long period of time. On the other hand, according to the present invention, the hydraulic cylinder moves at a speed determined by the oil flow rate regulated by the flow rate limiting orifice, and as the hydraulic cylinder moves, cream solder in the syringe is discharged from the discharge port. The amount of cream solder discharged is determined by the amount of movement of the piston within the syringe, and the amount of movement of the piston is determined by the amount of movement of the hydraulic piston of the connected hydraulic cylinder. The amount of movement of the hydraulic cylinder is determined by the amount of incompressible oil that flows into the hydraulic cylinder, and this amount of oil is determined primarily by the flow restriction of the flow restriction orifice and the pressure of the applied oil. is set sufficiently large compared to the discharge pressure of cream solder. Therefore, the amount of solder cream to be discharged is less affected by local fluctuations in its viscosity, and can be stably discharged at the amount determined by the setting of the flow rate limiting orifice and the setting of the oil pressure.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows the configuration of a cream solder discharging device according to the present invention. As shown in the figure, the pneumatic cylinder 1 includes an air supply/exhaust port B2 and an air supply/exhaust port C3. A pneumatic piston 4 in the pneumatic cylinder 1 is connected to a piston rod 5, and the piston rod 5 and the first hydraulic cylinder 6 are connected to each other.
It is connected to the first hydraulic piston 7 inside. The first hydraulic cylinder 6 is connected to the pneumatic cylinder 1 and includes an oil supply/drain port 8 and an oil supply/drain port C9. The oil supply/drainage port B8 is connected to the oil supply/drainage port D24 of the second hydraulic cylinder 10 by piping, and the oil supply/drainage port C9 is connected to the oil supply/drainage port D24 of the second hydraulic cylinder 10 via a flow rate limiting orifice 11 and a check valve 12 connected in parallel. The second hydraulic cylinder 10 has the same inner diameter as the first hydraulic cylinder 6, and is connected to an oil supply/drainage port F13 by piping. The second hydraulic piston 14 in the second hydraulic cylinder 10 is connected to a piston rod 15, and the other end is in contact with a piston 17 in a syringe 16. The syringe holding fitting 18 is
It is coupled to the second hydraulic cylinder 10 and holds a syringe 16. The syringe 16 is filled with cream solder 19, and the cream solder 19 is discharged from the discharge port 20. The first hydraulic cylinder 6, the second hydraulic cylinder 10, and the piping are filled with incompressible oil.

Next, the operation of the cream solder discharging apparatus of the present invention constructed as described above will be explained. That is, when compressed air at a constant pressure is supplied to the supply/exhaust port B2 and the supply/exhaust port C3 is left open, the pneumatic piston 4 moves toward the first hydraulic cylinder 6, and the piston 7 moves into the oil chamber B21. Oil is pushed out from the oil supply/drainage port C9, and the pushed out oil passes through the flow rate restriction orifice 11, flows into the oil chamber C22 from the oil supply/drainage port F13 of the second hydraulic cylinder 10, and is connected to the second hydraulic piston 14 and the piston rod 15. is moved toward the syringe 16. As a result, the syringe piston 17 moves in the direction of the discharge port 20 and discharges the cream solder 19 from the discharge port 20. The amount of cream solder discharged corresponds to the amount of movement of the syringe piston 17. Furthermore, when compressed air is supplied into the pneumatic syringe 1 from the supply/exhaust port C3 and the supply/exhaust port B2 is opened, the pneumatic piston 4 and the first hydraulic piston 7 move upward, and along with this, the piping is opened from the oil supply/discharge port B8. The piston rod 15, through which oil flows into the oil supply/drainage port D24 and moves the second hydraulic piston 14 upward, is pulled up. At this time, the oil in the oil chamber C22 flows into the oil chamber 21 through the check valve 12.

FIG. 2 shows changes in the amount of solder discharged when the viscosity of the solder cream in the solder cream discharge apparatus of the present invention having such a structure changes, in comparison with the case where a conventional cream solder discharge apparatus is used. As shown in Figure 2, P1 is
This is the pressure applied to the air chamber 34 of the conventional cream solder dispensing device shown in FIG. It is a characteristic line. If the viscosity of the cream solder decreases and becomes as shown by the discharge characteristic line L3, the discharge amount will significantly increase as shown by q12. Further, when the viscosity increases and the discharge characteristic line L2 becomes as shown, the discharge amount decreases significantly as shown in q11. The viscosity of cream solder is L3 or L2
In order to maintain the initial discharge amount q even if the pressure changes as follows, the pressure at P1 had to be decreased or increased by P2 or P1.

On the other hand, in the cream solder dispensing device of the present invention, P2 is the pressure applied to the air chamber 23 in FIG. The pressure that can be applied to the syringe is converted by the ratio of the area to the pressure receiving area. L0 shown in FIG. 2 is a characteristic line showing the relationship between the pressure applied to the flow rate limiting orifice 11 and the flow rate.
The amount of solder cream to be discharged is determined by the ratio between the area of the syringe piston 17 and the area of the syringe piston 17. Discharge characteristic line L4 is line L
This is a discharge characteristic line of cream solder having the same viscosity as 1, and is superimposed on line L0. Now, when a discharge amount of q is obtained at a pressure of P2, the pressure applied to the syringe piston 17 in the syringe is P1, and there is a pressure drop of (P2-P1) in the flow rate limiting orifice 11. At this time, if the viscosity of the cream solder changes from line L4 to L6 by the same amount as the change from line L1 to L3, the discharge amount will be q2.
2, and from L4 to L5, the discharge amount is q
21, but the range of variation from q is significantly smaller than in the conventional example.

The reason why the fluctuation in the amount of cream solder discharged can be reduced in this way is that the fluctuation in the flow rate is relatively small with respect to the fluctuation in pressure, as shown by the line L0 in FIG. This is because the supply means of

0012

[Effects of the Invention] As is clear from the description of the above embodiments, according to the present invention, even if cream solder with partially different viscosity is used, it is possible to stably supply cream solder with little variation in discharge amount. become. As a result, the cream solder can be applied uniformly onto the printed circuit board, improving the reliability of soldering components to the printed circuit board.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the configuration of a cream solder discharge device according to an embodiment of the present invention.

[Figure 2] Characteristic diagram explaining the operation of the device

[Figure 3] Cross-sectional view of a conventional cream solder dispensing device

[Explanation of symbols]

1 Pneumatic cylinder 2, 3 Supply and exhaust ports B, C 4 Pneumatic piston 6 First hydraulic cylinder 7 First hydraulic piston 8, 9, 13, 24 Oil supply and drain port 10 Second hydraulic cylinder 14 Second hydraulic piston 16 Syringe for cream solder 17 Syringe piston 20 Cream solder outlet

Claims (2)

[Claims] 1. Means for supplying oil into the hydraulic cylinder, the pressure of which is controlled so as to have a substantially constant flow rate, comprising a syringe containing cream solder and a hydraulic cylinder connected by a holding fitting that holds the syringe. A cream solder discharge device in which a piston provided in the hydraulic cylinder and a piston rod connected to the piston press a piston in the syringe to discharge cream solder in the syringe at a constant discharge amount. 2. A device for dispensing cream solder in a syringe, comprising a pneumatic cylinder operated by air pressure, and a piston connected to the piston in the pneumatic cylinder, and mechanically coupled to the pneumatic cylinder. a first hydraulic cylinder that is hydraulically operated; a second hydraulic cylinder to which the first hydraulic cylinder and each oil chamber in the cylinder are connected via piping; and a piston connected to a piston in the second hydraulic cylinder. An oil piping in which a rod is in direct or indirect contact with a piston in a syringe, a syringe holding fitting that holds the syringe is mechanically coupled to a second hydraulic cylinder, and the piston of the first hydraulic cylinder is operated to discharge oil. 2. The cream solder dispensing device according to claim 1, further comprising a check valve and a flow rate limiting orifice inserted in parallel.