JPS61175296A - Electron beam welding apparatus - Google Patents

Abstract

PURPOSE:To shorten the exhausting time by selectively switching a motor for driving a mechanical booster pump to specific number of pole as required thereby multiplying the exhaust capacity. CONSTITUTION:An object 1 to be welded is set on a rotary table 3 then a door 2 is closed to produce a signal for functioning a pneumatic vacuum valve 8 thus to communicate with first mechanical booster pump 19, then a timer is set (to T1) and to switch the drive motor for said booster pump 10 from 4-pole to 2-pole operation. Consequently, double speed operation is realized to double the exhaust capacity. Upon elapse of setting time (T1), the welding chamber 4 is evacuated by means of said booster pump 10 (2-pole), second mechanical booster pump 13 and a hydraulic rotary pump 15. Upon reaching to weldable vacuum, an electron beam is produced to execute specific welding. With such arrangement, insufficient power at start is compensated while the exhausting time is shortened.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to an electron beam welding device that performs welding in a vacuum atmosphere using the impact heat of an electron beam accelerated at a high voltage of around several tens of kilovolts. in.

In particular, the present invention relates to an exhaust system for a welding room in which electron beam welding is performed.

[Conventional technology]

Figures 4 and 5 are cross-sectional views showing a welding room for welding using this type of electron beam welding equipment and an exhaust system for this welding room. FIG. 5 is a sectional view showing the evacuation state when welding is completed and the door is opened. In the figure, is (1) a door (2) that can be opened and closed? Welding room with (
4) The object to be welded is set on the rotating table (3) in (5), which is installed at the upper part of the welding chamber (4), and the object to be welded (1) is irradiated with a -U hanging beam. Electron guns (6) and (9) for welding are connected to the welding chamber (4), and exhaust pipe (8) has a leak valve (7). A pneumatically operated vacuum valve is provided between the exhaust pipes (9) and (9) to communicate and cut off the communication between the two exhaust pipes (6) and (9). (A pair of first
and a second mechanical booster pump, this first and second
The mechanical push pumps OQ and α are equipped with two-pole drive motors C11) and (l) each consisting of an induction motor.
ie is provided. 0→, (]→ are the above first and second
Mechanical booster (between 1 and 0 → and 2nd
This is an exhaust pipe that connects the mechanical booster (13) and the oil rotary pump (13).

Next, the operation of the exhaust system will be explained with reference to the configuration diagrams of the exhaust system shown in FIGS. 4 and 5 and the time chart shown in FIG. 6.

When the door (2) is opened to set the workpiece (1) on the rotary table (3) in the welding chamber (4), the pneumatically operated vacuum valve (8) As shown in Figure 5,
first and second mechanical booster pump fli, (1
+) and oil rotary pump q→ to prevent atmospheric pressure from flowing into them and causing overload operation.

Next, as shown in FIG. ) starts evacuation, and it is confirmed that the degree of vacuum has reached a predetermined pressure of 5 x 1 Q'Torr (760 Torr (atmospheric pressure)) (this time is generally called the evacuation time). , the object to be welded (1) is rotated at a predetermined speed and welding by the electron beam is started.When the predetermined welding is completed, the pneumatically operated vacuum valve (8) is closed, and the leak valve (7) is closed. When the welding chamber (4) is opened and the inside of the welding chamber (4) reaches atmospheric pressure, the door (2) is opened and the object to be bathed (1) is taken out, completing one cycle of welding work.
During the cycle, the first and second mechanical booster pumps (
10), (1→ and oil rotary pump 0→ are operated continuously, and the drive motor 01 of the first mechanical booster pump 00 in this case) is a four-pole type, so its exhaust characteristics are as follows. As shown in Figure 2, the degree of vacuum is 76
At 0 to 30 Torr (broken line - 4 poles continuous), the exhaust time takes "T3" seconds. Note that the pressure difference between the suction side and the exhaust side of the first mechanical booster pump α0 or the second mechanical booster pump α1 is proportional to its output. That is, when the pressure difference is large, the output has a negative relationship, and the exhaust capacity is proportional to the internal volume of the pump and the rotation speed.

In addition, as mentioned above, the conventional exhaust system described above
Oil rotary pump (1→ and mechanical booster pump O1 or oil rotary pump (1→ and first mechanical booster pump (10) and second mechanical booster pump (
13, and in this case, the oil rotary pump 0→ and the first mechanical booster pump (10,
The exhaust capacity of the second mechanical booster pump (c) is:
There are more first mechanical booster pumps α than oil rotary pumps a9, and there are more second mechanical booster pumps than this. 7)E Many! For example, they are set at a ratio of 1:2:5, such as 8, and are configured so that they each have values close to each other so that work can be done effectively. Furthermore, four-pole three-phase induction motors are used as drive motors a1) and a+e for driving both the mechanical booster pumps 0 and α1.

[Problem that the invention seeks to solve]

As shown in the configuration diagram of FIG. 4, the exhaust system in a conventional pentagon beam welding device has a difference between the suction side pressure of the first mechanical booster pump α0 and the exhaust (III pressure).
That is, since the output (torque) of the drive motor is proportional to the pressure difference, the output must be more than doubled to obtain the same pressure difference. For this reason, if a two-pole drive motor is used, double the pumping capacity can be obtained by using a mechanical booster pump in four-pole operation. Most of the mechanical booster pumps have a small capacity of about 100 to 600 M'/Hr, and these can be used as the second mechanical booster pump a1.

This increases as the exhaust capacity increases.
Continuous operation for a long time (8 to 16 Hr/dag) at 0 rpm) has the disadvantage of shortening the life of the seal and causing abnormal heat generation in the pump and drive motor.

In particular, to explain the heat generation of the drive motor during two-pole operation, when exhausting the welding chamber (4) shown in Fig. 4,
As shown in the starting characteristic diagram in Figure 6, when the operating pressure of a drive motor (two poles) with a degree of vacuum of 760 (atmospheric pressure) 'Iorr is 1, this two pole drive motor has a starting current flowing through it. For example, when the internal volume of the welding chamber (4) is large, the time required to reach the operational pressure is T as shown in FIG.
It takes 4 (seconds), so the thermal to protect the motor is activated during this time.
There are examples of thermal activation at wT4-4 to 5SeC.

In addition, when we investigated the operating pressure, we found that the degree of vacuum was 1 to Q.
, IT'□rr also had cases in which the two-pole drive motor described in 1.1 became inoperable. This is because the starting load on the drive motor is excessive, making it difficult for the first mechanical booster pump ( ]O shown in FIG. 4 to rotate at high speed).

[Means for solving problems]

Exhaust system for electron beam welding loading according to this invention;
(Importantly used mechanical booster bore) 17) As a drive motor, the number of poles can be selectively switched.

[Effect]

In this invention, the drive motor that drives the mechanical booster pump is selectively switched to a predetermined number of poles as necessary, so power shortage during startup is compensated for.
Moreover, the exhaust time can be shortened.

[Embodiments of the invention]

The configuration of the exhaust system of the electron beam welding apparatus of this invention is almost the same as the conventional exhaust system shown in FIG. The number of poles of the drive motor 01) can be selectively switched between, for example, two poles and four poles, and the rotational speed of the drive motor is twice that of a two-pole motor or a four-pole motor. If you take advantage of this fact and convert the 4-pole drive motor that drives the mechanical booster pump to a 2-pole drive motor, the rotation speed will double,
This doubles the exhaust capacity of the pump.

As shown in the operation time chart of FIG.
The 4-pole drive motor performs continuous operation, and when the 2-pole drive motor reaches the operating pressure midway, it switches to the 2-pole drive motor for high-speed rotation, and the exhaust time (
T2 seconds). The reason why two-pole operation is possible is because it performs powerful four-pole operation (1800 rprn) at startup.

Since the exhaust system in the electron beam welding apparatus of the present invention is configured as described above, its operation will be explained using the time chart shown in FIG. 1. As with the conventional exhaust system, as shown in FIG. After setting the workpiece (1) to the specified position on the rotary table (3), open the door (2).
), the pneumatically operated vacuum valve (8) is activated by the signal to establish communication between the welding chamber (4) and the first mechanical booster pump (10), and a timer is set (time T0 seconds). When the mechanical booster pump 1 (], drive motor α1 0) is switched from 4-pole operation to 2-pole operation, 1
Double speed operation from 800 rpm to 6600 rpm,
Its exhaust capacity can be doubled. As shown in the characteristic comparison diagram in Figure 2, the time "TI" seconds set by the timer is set to be equal to the pressure at which two-pole operation is possible, and from then on, the first mechanical booster pump (two-pole)
, the welding chamber (4) is evacuated by the second mechanical booster pump (1 port) and the oil rotary pump 0→.

The welding pressure, that is, the degree of vacuum, is 5X10To
When rr is reached, an electron beam is generated and predetermined welding is performed. As shown in the operation time chart in Figure 6, if we compare the evacuation time with the case where the first mechanical booster pump αQ is continuously evacuated using a four-pole (drive motor α■), it is inevitable that the This is better than when operating with a two-pole drive motor by the time shown in ('rs T2), and this time difference was found to be more than a few seconds when conducted in an experiment using a welding chamber (4) with a volume of 150 mm. Ta.

〔Effect of the invention〕

As described above, according to the present invention, the drive motor of the mechanical booster pump is switched to a predetermined number of poles as necessary, so that the lack of power at startup is compensated for, and the inside of the welding chamber (4) is Not only can the evacuation time to create a vacuum be shortened, but according to this invention, the pump main body size can double the same evacuation capacity as a 4-pole pump, so the evacuation capacity can be doubled. Since it can be made smaller than the same four-pole bomb size, it can be manufactured at low cost as an exhaust system for electron beam welding equipment, and has the excellent effect of reducing the installation area.

[Brief explanation of drawings]

Fig. 1 shows the operation diagram of the exhaust system of the electron beam welding device of the present invention. Fig. 2 is a comparison diagram of the exhaust characteristics of the exhaust system of the present invention and the conventional exhaust system. Fig. 3 shows the exhaust characteristics of the exhaust system of the present invention and the conventional exhaust system. A comparison diagram of the exhaust characteristics of the exhaust system and the starting characteristics of the drive motor. Figures 4 and 51 are cross-sectional views showing the exhaust system of the welding room. The figure shows the exhaust state with the door open after welding is completed. FIG. 6 is an operation time chart of a conventional exhaust system. In the figure, (4) is the welding chamber, (8) is the pneumatically operated vacuum valve, OQ is the first mechanical booster pump, (1
:'el'im2 mechanical pump, (11
) <sQ is 1 drive electric motor, (1 is an oil rotary pump. The same reference numerals in 1 figure indicate the same or corresponding parts. Agent: Patent attorney Sanro Kimura - Prisoner Guno 9Q Tomoe

Claims (5)

[Claims] (1) A welding chamber in which electron beam welding is performed is evacuated by an oil rotary pump and a mechanical booster pump disposed between the oil rotary pump and the welding chamber, wherein the mechanical booster pump An electron beam welding device characterized in that the number of poles of a drive motor that drives a pump is selectively switched as necessary. (2) The electron beam welding apparatus according to claim 1, wherein a plurality of mechanical booster pumps are arranged between the oil rotary pump and the welding chamber. (3) The electron beam welding apparatus according to claim 1, wherein the drive motor is a three-phase induction motor. (4) The electron beam welding apparatus according to claim 1, wherein the number of poles of the drive motor is selectively switched between two poles and four poles. (5) The electron beam welding apparatus according to claim 1, wherein a pneumatically operated vacuum valve is provided between the welding chamber and the mechanical booster pump.