Hydraulic bulging machine bulging force control system (2)

Third, two improvement schemes and use effects of the bulging Force Control System

1. bleed valve end overflow method

This program is designed for the 1250/850/850 bulging machine with a bleed valve. On the valve seat of the device, the drain hole and the fixed screw hole are processed, and the throttle plug is installed in the drain hole. External ordinary relief valve or imported electromagnetic proportional valve. The two chambers of the relief valve are communicated with the two chambers of the deflation valve seat to drain through the overflow valve when the bulging force approaches or is greater than the max value in P. It is worth noting here that the liquid flow control of the flow valve must be very sensitive. The opening does not cause the liquid to drop out due to the too fast discharge, which causes the pipe to wrinkle and produce waste. With the above control measures, the use of this device in forming thin-walled T-shaped metal pipe fittings was developed. For copper alloys with smaller σb, the actual use effect is particularly outstanding, and the yield is as high as 95% or more. However, the disadvantage is that it is only suitable for the bulging of the T-shaped pipe with a max of less than 32 MPa in the bulging pressure P, and it is incapable of bulging for the T-shaped pipe with a diameter of more than 32 MPa in the P. This is because the general control range of ordinary relief valves and proportional valves are less than 32 MPa. Figure 2 shows the bulging principle and the bulging force control implementation orientation.

Figure 2 Schematic diagram of the bulging principle and the implementation of the bulging force control orientation map
A——Exhaust valve end overflow method implementation orientation
B——Supercharger end overflow method implementation orientation
C——check valve to be removed when implementing the supercharger end overflow method

2. Supercharger end liquid flow method

One of the advantages of the 1250/850/850 bulging machine is its supercharger. The supercharger has a pressurization ratio of 1:8, and can establish an initial forming minimum pressure P within 200 MPa required for forming in the initial stage of forming the pipe. As can be seen from Fig. 2, the original device is equipped with a check valve in the infusion pipe connecting the supercharger and the horizontal cylinder telescopic tube, which makes the T-shaped pipe fitting unable to overflow by rising when it is raised in the internal pressure P. Buck or voltage regulation.

To solve the problem of step-down voltage regulation when P is increased in the forming of T-shaped pipe fittings, it is not thorough to design the overflow device only between the telescopic pipe and the one-way valve. The result is exactly the same as that of the first one. To this end, it is considered to remove the check valve and design an overflow device at the rear of the supercharger so that when the pressure rises during the forming process, it is converted by the supercharger in an 8:1 manner, and the overflow behind the supercharger The flow device is adjusted. The commonly used ordinary relief valve or imported electromagnetic proportional valve can be used in this overflow device. When forming different sizes of T-shaped pipe fittings, the overflow pressure can be adjusted by changing the size of the electromagnetic proportional valve electrical signal on the operating table.

The above scheme ensures that any point in the internal pressure P can be controlled to ≤200 MPa, that is, it overflows immediately when P is ≥P within max, thereby avoiding or reducing the cracking of the pipe fitting due to max within ≥P in P . At the same time, after the 8:1 conversion in P, the pressure in the tail chamber of the supercharger will not exceed 25 MPa, which ensures the safety and reliability of the overflow system. The implementation of this design is shown in Figure 2. The actual use proves that after adopting this design scheme, not only the thin-walled low-strength alloy (such as copper alloy, aluminum alloy, etc.) pipe fittings with a bulging force P of <32 MPa in the T-shaped pipe, but also the stainless steel with a bulging force of 3 to 200 MPa. High-strength or thick-walled T-shaped pipe fittings such as carbon steel and titanium alloy have excellent forming effects and the yield is over 95%.

The yield of the T-shaped pipe fittings of the 1250/850/850 bulging machine under different control modes, as well as the defect types and production parts are listed in the table.

Table 1250/850/850 bulging machine yield of T-shaped pipe fittings under different control modes

Fourth, the conclusion

(1) In the forming process of T-pieces, it is necessary to pay attention to the influencing factors such as material, specification, forming speed and lubrication condition, and at the same time pay more attention to the important influencing factor of bulging force.

(2) The 1250/850/850 bulging machine must control the bulging force. The two control methods proposed in the paper can improve the product quality and yield.

(3) The supercharger end overflow method improves the performance of the 1250/850/850 bulging machine, which is not only suitable for high-strength and thick-walled T-shaped metal pipe fittings, but also suitable for low-strength and thin-walled T-shaped metal pipe fittings. Forming.

Previous page