JPS59232621A - Method for controlling longitudinal warp in mechanical expander - Google Patents

Abstract

PURPOSE:To decrease the longitudinal warp of a pipe within the limits of tolerance by changing the height of a gripper, in expanding a UOE steel pipe by a mechanical expander. CONSTITUTION:In inserting a pipe A to a mechanical expander, the height of a gripper 1 is set higher than that to be set for a straight pipe A, when the pipe A has an upward warp. Further, the height of gripper 1 is set lower to the contrary when the pipe A has a downward warp. And pipe bearing rolls 3 are lowered, at the time of inserting the pipe A to a head 5, so that the pipe A is supported only by the gripper 1 and a supporting roll 4. This lowering command is outputted by detecting the pipe end with the aid of a proximity switch 7 provided to the lower side of the head 5. Next, the pipe A is expanded while advancing a gripper dolly 2, and at the same time, the position of gripper 1 is changed at every pass in accordance with the advanced distance of the dolly 2. That is, when the pipe A has an upward ward, the gripper 1 is lowered in sequence, and when it has a downward warp, the gripper 1 is raised. And when the half length of pipe A is expanded, the remaining half is expanded from the other end.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for controlling vertical bending in a mechanical expander.

In the manufacturing process of UOE steel pipes, bending of the steel pipes occurs due to thermal strain due to welding heat input. Also, bending lines occur in a mechanical expander when the pipe is expanded, but in the past, vertical bending lines among these bending lines have not been controlled in the mechanical expander.

The present invention has been made in view of this point, and its basic feature is to lower the vertical curved sill to within the tolerance range by changing the height of the gripper of the mechanical expander.

In Figure 1, (a) is a pipe, (1) is a gripper,
(2) is a gripper trolley, (3) is a pipe receiving roll, (4
) is a support roll, (5) is a head, and (6) is a head support roll.

In the present invention, first, when loading the pipe (A) into the mechanical expander, if the pipe (A) is flat, the height of the gripper (1) is adjusted to fit the straight pipe (A). Set it higher than the case. Conversely, in the case of a lower question, set it downward. This set value ()Io) is expressed by the following formula in FIG.

HO= L tanθ〒L=■ (where R is the radius of curvature) When the pipe (A) is loaded into the head (5), the pipe 0) is supported only by the gripper (1) and support roll (4). The pipe receiving roll (3) is lowered so that the pipe receiving roll (3) is lowered. This lowering command is issued by detecting the end of the pipe using a proximity switch (7) provided below the bed (5).

Next, the gripper cart (2) is moved forward to expand the pipe, and at the same time, the gripper (1) is changed for each bus in accordance with the bending of the pipe (A) according to the forward distance. That is, pipe (
If b) is at the top, Gritsuba (1) * Gradually lower it. The gripper height H at this time is expressed by the following formula in FIG.

H'=
I'm going to raise it.

An example of the trajectory of the gripper (1) at this time is shown at 2 in FIG. 1 CB).

After expanding the pipe (A) to half length in this way, raise the pipe support roll (3) fully and lower the gripper (1) so that the pipe (A) does not rub against the head (5). Pull it out from the head (5).

Note that the calculation and control of the height of the gripper (1) described above is performed by a computer.

Next, examples will be shown.

Pipe expansion was performed under the conditions shown in Table 1. The gripper height was varied in three stages.

In Table 1, Nu 1 head is the half length from one end of the pipe,
N [The L2 head expands the half length from the other end. Further, 11 is the clearance of the head (5) with respect to the inner diameter of the pipe (a), and δ is the deviation between the high center and the head center, as shown in FIG.

Table 2 shows the bends before pipe expansion and the bends after pipe expansion. The curve values are those of the points shown in FIG.

' 〃 In this example, in the case of a 16 x 6.4 pipe, the top surface of 48 mm was improved to 15 mm, and in the case of a 16 x 20.6 pipe, the top surface depth was improved from 50 mm to 17 m.As explained above in Table 2, The effects of the present invention are very large, and each pipe can be corrected according to its bending value.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the method of the present invention, FIG. 2 is an explanatory diagram of gripper position setting, FIG. 3 is an explanatory diagram of the conditions of the embodiment, and FIG. 4 is an explanatory diagram of the bending value. (1)...Gripper, (2)...Gripper trolley, (
3)...Pipe receiving roll, (4)...S,N
)O-ru, (5)...Het, (6)...Hetsahotrol, (7)...Proximity switch.

Claims (1)

[Claims] A method for controlling vertical bending in a mechanical expander, which comprises controlling the vertical bending of a pipe by changing the gripper height of the mechanical expander during pipe expansion using a mechanical expander in a UOE steel pipe manufacturing process.