JPS63132785A - Electron beam welding method - Google Patents

Abstract

PURPOSE:To uniformize the quantity of shrinkage in the axial direction by maintaining a target transmitted beam current to the difference between the target transmitted beam current and a stored transmitted beam current after cylindrical bodies make a round around the circumference and return to the original position. CONSTITUTION:A command of an incident beam IIN corresponding to the target transmitted beam current I'OUT(S) is given from a controller 18 to a electron beam welding machine 6 and the incident beam current IIN is applied from the electron beam welding machine 6 to a joint part and the welding is performed. Since a transmitted beam current IOUT is not generated for a while at the time of starting the welding, even if the cylindrical bodies 1 and 2 make a round and return to the position K=1 in the peripheral direction, for a while, a signal of I'OUT(S)=IOUT(S) is given to the controller 18 and the transmitted beam current IOUT is controlled to a fixed value. The welding is performed while being controlled so as to attain the target transmitted beam current I'OUT(S) after subtracting the transmitted beam current at the time of starting the welding from the target transmitted beam current in case the welding is performed properly from the position where the transmitted beam current starts to rise.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an electron beam welding method in which the amount of axial contraction of a cylindrical body is made uniform at any position in the circumferential direction of the cylindrical body. .

[Prior Art] A conventional electron beam welding method will be explained with reference to FIGS. 6 and 7. The ends of cylindrical bodies 1.2 such as pipes or hollow drums having the same radius are brought into contact with each other, and the cylindrical bodies 1.2 Alternatively, the entire circumferential surface of the joint portion 3 is welded by the electron beam 4 while rotating one or both of the electron beams 4 about the axis of the cylindrical body 1.2 using the reference position O@ as the welding start point. . 5 is a weld bead.

Joint part 3 of cylindrical body 1.2 during the above-mentioned electron beam welding
The relationship between the circumferential position (angle) and the incident beam current is expressed as
To explain with a diagram, at the start of welding, the incident beam current projected to the joint part 3 while rotating the cylindrical body 1.2 is set at a steady value (a predetermined value that allows complete welding to the inner circumference of the member).
When it reaches a steady value, weld the entire circumference of the cylinder 1.2 with a constant incident current, and only the angle θ is formed by the angle at which the incident beam current reaches a steady value at the start of welding. Welding is performed using a steady-state incident beam current with partial overlap up to the previous angle, and then the incident beam current is gradually lowered to zero to complete welding.

When welding is performed as described above, the cylinder 1.2 will have a healthy back surface even on the inner surface, not only in the part welded with a steady-state incident beam current, but also in the part welded with an incident beam current that gradually increases at the start of welding. A bead is formed and a complete weld is made.

[Problems to be solved by the invention] However, in the conventional electron beam welding method described above, in order to perform complete welding in which a healthy back bead is formed on the entire circumference of the joint, welding is performed at a steady value of the incident beam current. The portions where this occurs partially overlap, and the amount of heat input is greater in the overlapped portions than in other portions of the circumferential surface. Therefore, the amount of heat shrinkage in the axial direction of the cylindrical body 1.2 after welding is larger in the overlap part than in other parts (line B in Fig. 5), and the welded cylindrical body 1.2 is bent with the overlap part as a reference. Put it away.

In view of the above-mentioned circumstances, an object of the present invention is to provide an electron beam welding method that completely welds the entire circumferential surface of a joint and prevents bending of the cylindrical body due to contraction after welding. It is.

[Means for Solving the Problems] The present invention involves making the end surfaces of two cylindrical bodies face each other and welding the entire circumferences of the facing parts with an electron beam while moving the welding machine and the cylindrical bodies relatively in the circumferential direction. In the electron beam welding method, at the start of welding, the beam current projected from the welding machine is gradually increased, and the transmitted beam current that passes through the cylindrical body joint part to the side where the welding machine is not installed is applied to the cylindrical body. When the transmitted beam current reaches a predetermined target transmitted beam current that enables proper welding, the target transmitted beam current is held constant and the cylindrical body is Perform welding in the circumferential direction, and when the welding completes one revolution and reaches a position where the transmitted beam current at the start of welding is not zero,
Welding is performed so that the subsequent target transmitted beam current becomes the difference between the target transmitted beam current that enables proper welding and the stored transmitted beam current.

[Function] When electron beam welding is started while gradually increasing the beam current, the transmitted beam current passing through the joint and the circumferential position of the cylinder are stored in the memory, and the transmitted beam current is calculated in advance. Once the target transmitted beam current reaches the target that allows for proper welding, welding is performed while keeping this constant.
- Once the target transmitted beam current returns to the original position, welding is performed while maintaining the target transmitted beam current at the difference between the target transmitted beam current and the stored transmitted beam current. Therefore, the amount of heat input to the cylindrical body is approximately equal at any position in the circumferential direction of the cylindrical body, and the amount of contraction in the axial direction is also approximately equal.

[Example] Hereinafter, an example of the present invention will be described with reference to the accompanying drawings.

1 and 2 show an embodiment of the present invention, in which 6 is an electron beam welder for welding the joint portion 3 of the cylindrical body 1.2;
8 is a drive roller that supports the cylindrical bodies 1 and 2 and rotates the cylindrical body 1.2, and 8 is a position detector that is connected to the drive roller 7 and detects the position (angle) in the circumferential direction of the cylindrical body 1.2. , 9 is the transmitted beam current transmitted through the joint part 3 to the inner circumferential side of the cylindrical body 1.2 out of the incident beam current ■IN projected from the electron beam welding machine 6 and entering the joint part 3! . ,1
IO is a signal processing device for averaging the measured transmitted beam current over time; 11 is the transmitted beam current I at the start of welding; The circle of the cylindrical body 1.2 detected by the position detector 8 when the incident beam current IIN is gradually increased until U reaches the target value (target transmitted beam current ■.UT(S) described later). A memory 0UT(K) for storing the circumferential positions IK-1, 2, 3, . . . n and the transmitted beam current at a position corresponding to the circumferential position detected by the transmitted beam current detector 9; Reference numeral 12 indicates a setting device for setting a target transmitted beam current I which has been determined in advance through experiments or the like and allows proper welding, and 13 indicates a transmitted beam current given from the signal processing device IO. , 1 and the target transmitted beam current I set by the setting device 12, OUT (S), and calculate the transmitted beam current deviation. )
and the target transmitted beam current set by the setting device 12!
15 is 0UT (S).The cylinder detected by the position detector 8 is A switch 1.2 is configured to turn on and off contacts 16 and 17 connected in parallel depending on the position in the circumferential direction of the body 1.2, and 18 is an incident beam current corresponding to the transmitted beam current signal from the calculator 13. This is a controller that determines (1)IN and controls the incident beam current (2)IN of the electron beam projected from the electron beam welding machine 6.

At the start of welding, the changeover switch 15 is turned on to the contact IB and turned off to the contact 17, so the setting device 12 and the computing device 13 are connected, and the setting device 1
2, the arithmetic unit 14, and the arithmetic unit 13 are in a cutoff state.

The setter 12 gives the target transmission beam current required for proper welding to the calculator 13, and when the 0UT(S) drive roller 7 is driven to rotate the cylindrical body 1.2 and welding is started, the calculation is performed. The target transmitted beam current is sent from the device 13 to the controller 18! is added, and the control 0UT(S) unit 18 sets 0UT corresponding to the target transmitted beam current.
(S) The incident beam current IIN is determined, and a command for the incident beam current IIN is given to the electron beam welding machine 6 from the controller 18, and the incident beam projected from the electron beam welding machine 6 and incident on the joint portion 3 is The beam current ■IN gradually rises (see Figure 3 (a)).

As the incident beam current ■IN is gradually increased, the third
As shown in figure (b), the transmitted beam current ■ transmitted through the joint part 3. 8. It starts to rise gradually with a time delay. This transmitted beam current ■. , 1 is a transmitted beam current detector 9 and a cylindrical body l.

-1, 2, 3, .
The transmitted beam current difference is determined by the arithmetic unit 13. Therefore, when the transmitted beam current difference becomes zero, that is, the transmitted beam current ■ becomes the target transmitted beam current I OUT OUT
(S) Then, from now on, the transmitted beam current I. Control 0UT(
S) A controller 18 controls the incident beam current IIN and the transmitted beam current I. Constant value control of Ua is performed (Fig. 3 0)
) (see b)).

On the other hand, as described above, when the incident beam current 'IN is gradually increased, the position in the circumferential direction of the cylindrical body 1.2 detected by the position detector 8 is -1°2.3. -, n and the circumferential position -1, 2° 3, ..., n, the transmitted beam current detected by the transmitted beam current detector 9 and averaged by the signal processing device 10 is ) (K-1, 2,
3, -..., n) are stored in the memory 11.

A transmitted beam current I detected by a transmitted beam current detector 9.

The reason why UT is averaged by the signal processing device IO is as follows. In other words, the transmitted beam current l0UT is as shown in Figure 3 (b).
Although it is shown as a straight line in FIG. 4, it actually has a wave shape as shown in FIG. m.

If the transmitted beam current l0UT itself at m+1 is used, the error will be large. Therefore, the transmitted beam current every minute time At! . 8. If you calculate this, integrate it for a time t that is shorter than the time the position of the cylinder 1.2 reaches, for example, from n to n+1, and average it by dividing the integrated value by t, the measurement error will be small and accurate. This is because it allows for better control.

Transmitted beam current output from signal processing device IO■
OUT becomes the target transmitted beam current I
0UT(S), hereafter the circumferential position of the cylinder 1.2 and the transmitted beam current ■OUT is the memory 11
is not memorized.

The cylindrical body 1.2 is welded and goes around once, and the position in the circumferential direction is −1.
When it returns to , the position detector 8 detects -1, and the switch 15 is switched based on the -1 detection signal, leaving the contact 18 and turning on the contact 17.

Thereafter, the transmitted beam current 1 (K- 1,2
, 3゜0UT(K) ..., n) are sequentially sent from the memory 11 to the computing unit 14, and the computing unit 14 calculates the target transmitted beam current I' before the end of welding as 0UT(S) OUT(S) 0UT. (S) -1OUT(K)V
-■ (K= 1. 2. 3.--., n) ...(D, this target transmitted beam current "0UT(S
) is output from the arithmetic unit 14 and sent to the controller 18 via the arithmetic unit 13, and from the controller 18, a command for the incident beam current IIN corresponding to the target transmitted beam current I' is sent to the electronic An incident beam current IIN is applied from the electron beam welding machine 6 to the joint portion 3 to perform welding.

In Fig. 3 (b), since only a transmitted beam current of 1 OUT is generated for a while at the start of welding, '0UT (K) is zero, and therefore the cylinder 1.2 makes one revolution and reaches the position in the circumferential direction. Even if it returns to -1, it remains 0UT(';) 0 for a while.
The signal of UT(S) is given to the controller 18 and I'
■I and transmitted beam current■. , 1 constant control is performed.

However, from the position where the transmitted beam current l0IJT begins to rise at the start of welding, the target transmitted beam current I when welding is performed properly. Subtract the transmitted beam current at the start of welding from UT(S) to 0UT(K).
S) Welding is performed under control. Since the transmitted beam current ■OUT at the start of welding is gradually rising, the target transmitted beam current I'0UT (S) at the end of welding is 1.2 for the cylindrical body.
gradually descends depending on the circumferential position of

The reason why the transmitted beam current is controlled to satisfy the above equation (1) at the end of welding is as follows.

Ru. In other words, the formula (+) is I san I' 0UT(S) 0UT(S) +10LIT(K)
(K-1,2,3,...,n)-...Ci), and the transmitted beam current Io at the start of welding, a(K) and the target transmitted beam current at the end of welding"0UT(S) This is because if 0UT(S) is set so that the sum of 0UT(S) matches the target transmitted beam current I necessary for proper welding, good welding can be performed.

When welding is performed in the manner described above, welding is performed so that the transmitted beam current in the range θ' in Fig. 3 (a) and (b) is approximately the same in total as in the other areas Δ. The amount of contraction of the cylindrical body 1.2 in the axial direction is approximately the same at any position in the circumferential direction of the cylindrical body 1.2, as shown by line A in FIG. Can prevent bending.

In the embodiments of the present invention, a case has been described in which a signal processing device is provided to average the transmitted beam current, but it should be noted that it can also be carried out without a signal processing device, and that the welding machine is moved in the circumferential direction of the cylinder without rotating the cylinder. It goes without saying that the present invention can be implemented even by rotating the present invention, and that various other changes can be made without departing from the gist of the present invention.

[Effects of the Invention] According to the electron beam welding method of the present invention, since welding is performed so that the transmitted beam current is equal at any position in the circumferential direction of the cylinder, the amount of contraction in the axial direction of the cylinder after welding is reduced. is substantially uniform, so the cylindrical body does not bend, and various excellent effects can be achieved, such as being able to obtain a good product.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of an example of an electron beam welding apparatus for performing the electron beam welding method of the present invention, Fig. 2 is an explanatory diagram of a state in which electron beam welding of a cylindrical body is performed, and Fig. 3 (A) is a graph showing the relationship between the circumferential position of the cylindrical body and the incident beam current in the method of the present invention, and FIG. 3 (b) is a graph showing the relationship between the circumferential position of the cylindrical body and the transmitted beam current, FIG. 4 is an explanatory diagram of the reason why the transmitted beam current is averaged by the method of the present invention, and FIG. FIG. 6 is a graph showing the relationship between the circumferential position of the cylindrical body and the incident beam current according to the conventional method, and FIG. 7 is a general explanatory diagram of electron beam welding. In the figure, 1.2 is a cylindrical body, 3 is a joint part, 4 is an electron beam,
5 is a welding bead, 6 is an electron beam welder, 8 is a position detector, 9 is a transmitted beam current detector, IO is a signal processing device,
11 is a storage device, 12 is a setting device, 13.14 is an arithmetic unit, 1
5 is a changeover switch, and 18 is a controller.

Claims (1)

[Claims] 1) In an electron beam welding method in which the end surfaces of two cylindrical bodies are opposed and the entire circumference of the opposed parts is welded with an electron beam while the welding machine and the cylindrical body are moved relative to each other in the circumferential direction, at the start of welding, the welding The beam current projected from the welding machine is gradually increased, and the transmitted beam current that passes through the joint part of the cylinder to the side where the welding machine is not installed is stored in a memory corresponding to the position in the circumferential direction of the cylinder. When the transmitted beam current reaches a predetermined target transmitted beam current that allows proper welding, the target transmitted beam current is held constant and welding is performed in the circumferential direction of the cylindrical body, and the welding is completed once. When the transmitted beam current at the start of welding reaches a position where it is not zero, welding is performed such that the subsequent target transmitted beam current is the difference between the target transmitted beam current that allows proper welding and the stored transmitted beam current. An electron beam welding method characterized by: