JPS6043813B2 - Thick wall UO steel pipe forming method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for forming thick-walled UO steel pipes in the UO steel pipe manufacturing process, and particularly relates to a method for forming thick-walled UO steel pipes, particularly when the plate thickness is 19-Inm or more (preferably 25.4wr!n or more) and the abutment interval after o-forming is The present invention relates to a thick-walled UO steel pipe forming method that controls the process to suit subsequent welding operations and has good forming efficiency.

The UO manufacturing method is a typical manufacturing method for large diameter welded steel pipes.

In this UO manufacturing process, the abutting portions of the o-formed steel pipes are tack welded, but at this time, as shown in Figure 1, the distance δ between the abutting portions after o-forming (hereinafter referred to as the gap) This has a great effect on workability during welding and the quality of the welded part, and if no gap is created, impurities (dust, oil, etc.) that collect in the abutting part cannot be completely removed, resulting in weld defects. On the other hand, if the gap is too wide, defects such as weld cracks will increase. Of course, tack welding machines usually have a mechanism that forcibly creates a gap before welding and an external restraint mechanism that forcibly reduces the gap to zero during welding so that the above problems do not occur. However, in the case of thick-walled steel pipes, which are the object of the present invention, the load acting on the above-mentioned mechanism increases significantly in proportion to the square of the plate thickness, so the existing mechanism and load capacity are insufficient, and welding work is required. This will significantly reduce the properties of the weld, and will also have a negative impact on the quality of the weld. Therefore, obtaining an appropriate gap after O-forming is important and effective for improving welding workability and quality, especially when the plate thickness is 1.
When manufacturing thick-walled steel pipes of 9 TWL or more, not only is the need for gap control becoming extremely large, but the allowable range of the target gap amount is also becoming smaller. In addition, the plate thickness is 25
．． In the case of manufacturing thick-walled steel pipes of 4 Tnm or more, gap control becomes an essential condition. This gap varies in a complicated manner depending on the characteristics of the material to be formed (particularly plate thickness and strength) and O-forming conditions (especially O-forming load), but the following methods have been conventionally known as gap control methods. be.

A method in which a key is provided in the upper mold during O molding, and the abutting part sandwiches the key, a method in which the molding load is controlled, and a combination of these methods. Both of these methods are methods of controlling the gap by changing the O-forming conditions, but they are virtually impossible to employ for the following reasons in the production of thick-walled steel pipes, which are the subject of the present invention.

Method 1 a) will damage the key.

In 110 molding, it is necessary to mold into a shape close to a perfect circle, but for this purpose, it is necessary to make the O molding load sufficiently large.

On the other hand, the gap generally becomes smaller as the O-forming load increases and as the plate thickness increases. Therefore, when forming thick-walled steel pipes, the method of
There is almost no degree of freedom to balance the objectives of (increasing the forming load sufficiently) and ensuring an appropriate amount of gap (keeping the 0 forming load low), or in order to increase the degree of freedom, it is necessary to use an O-breath. The capacity must be increased considerably, and in this method, the O-forming efficiency becomes extremely poor. 111 In addition, since the tolerance range of the target gap amount is small for thick-walled steel pipes, the above method can be used for forming materials having various thicknesses and strengths, and for various pipe diameters.
It is impossible to satisfy that demand.

Unlike conventional methods, the present invention improves the U forming conditions, making it extremely simple industrially and making it easy to keep the gap amount within the allowable range even if the plate thickness, strength, and tube diameter of the material to be formed differs. The objective is to provide a thick-walled UO steel pipe forming method that allows for 1U
0 In the steel pipe manufacturing process, the punch shape is 0.65≦2(
B+t)/D≦0.93, and punch height H or/
and punch width? Using a U-punch with a variable If the distance is larger than the distance, H/2B is largely adjusted, the variable punch height and/or punch width are set so that the target distance is achieved, and U-forming is performed followed by zero-forming.

however? ; Punch width (Tlr!n), D; Vibrator outer diameter (W
m), t: Thickness (Tllm) of the material to be formed. 2Uq
In the steel pipe manufacturing process, the punch shape is 0.65≦2(B
+t)/D≦0.93, 0.22≦21. /2B≦0.
42 and 0.28≦H/2B≦0.45 and punch height H or/and punch width? Using a U-punch with a variable
If the abutting part interval after molding is smaller than the target interval, H/
If 2B is smaller than the target interval, then H/2
It is characterized in that the variable punch height and/or punch width are set so that B is largely adjusted to achieve the target spacing, and U-forming is performed followed by zero-forming.

however? ; Punch width (Wln), D; Vibrator outer diameter (Tlr
m), t: Thickness of the material to be formed (7177, 21.; Width of punch height adjustment part (Tlrln), H: Punch height (gourd)
It is. The method of the present invention will be explained in detail below with reference to examples shown in the drawings. FIGS. 2A and 2B are cross-sectional views of a conventionally used U-punch, and FIG. 3 is a cross-sectional view of an example of a U-punch used in the method of the present invention. There are two types of conventional U punches: a single cylindrical type as shown in Figure 2a, and a compound cylindrical type as shown in Figure 2b, but both of these have a punch height H or/and a punch width. It was impossible to change.

On the other hand, the punch according to the present invention has a punch height H or/and a punch width? For example, as shown in Figure 3 (Figure 3 shows an example of variable punch height), H/2B can be changed depending on the thickness, strength, and pipe diameter of the material to be formed. Characteristically different from law. In)? is the U-punch width, and the punch height H is the height from the punch maximum width position (in the case of FIG. 3, coincident with the center of the side punch 1). The punches used in the method of the present invention shown in the example of FIG. 3 include side punch 1, bottom punch 5, block 3,
Consisting of a spacer 4 and a punch spacer 6, the bottom punch 5 is movable in the vertical direction, and by adjusting the height of the spacer 4, the punch height H (i.e. H/2
B) can be changed.

Although not shown in FIG. 3, the left and right side punches 1, 1, the punch spacer 6 and the side punch 1, and the bottom punch 5 and the block 3 are each fixed with bolts. Also, punch width? An example of variable is
Insert a spacer on the surface of the U punch shown in Figure 3 that joins with the inner surface of side punch 1 to determine the punch width. change.

Also, punch height H and punch width? If and is variable,
To change the punch height H, use the method shown in Figure 3 to change the punch width?
Changes are made using the method described above. FIG. 4 is a sectional view illustrating an example of the use of the U punch used in the method of the present invention, and FIG. 4a shows an example of use when it is desired to widen the gap, with H/2B being minimized.

In this case, the steel plate 7, which is the material to be formed, is bent along the side punches 1, and the bottom punch 5 is not involved in U-bending. It is bent by the uniform bending moment that occurs when it is bent along . Figure 4b is an example of use when you want to narrow the gap, by inserting a spacer 4 between the block 3 and the bottom punch 5 and increasing the punch height.
Make it bigger. In this case, the steel plate 7 is first bent by the bottom punch 5, and then the left and right sides are bent. It is bent along the punches 1,1. The relationship between the gap after 0 molding and H/2B is
It is also affected by the strength and thickness of the steel plate, but decreasing H/2B widens the gap, and increasing H/2B narrows the gap, which affects the thickness and strength of the steel plate. Adjust H/2B accordingly to obtain the target gap amount, and then adjust the punch height H and/or punch width? Set.

The basic idea of the present invention is the punch height H or/and punch width? The gap after O molding is controlled by making it variable to control H/2B, and the 0 molding condition is fixed at a condition suitable for improving the roundness of the vibrator, thereby improving molding efficiency. The goal is to control the gap amount so that the steel pipe shape is excellent and the welding work is convenient. Generally, the gap amount is is small, so it is necessary to limit the shape of the punch in order to exhibit the effects of the present invention.

The condition is 0.65≦2(B+t)/D≦0.93...
・(1) However? ; Punch width (Wn), D; Vibrator outer diameter (
T! Rm), t: Thickness (TOn) of the material to be formed. (
1) The upper limit value of 0.93 in the formula is 0.93 for the material to be formed after U forming.
It is determined based on the geometric relationship that allows the material to be carried into the O-press machine, and if this upper limit is exceeded, the material to be formed cannot be carried into the O-press machine. Furthermore, if the lower limit of equation (1) is less than 0.65, for thick-walled steel pipes targeted by the method of the present invention, the gap after O-forming will hardly open even if H/2B is reduced, or H/2B may be changed. However, the gap control fee will be almost eliminated. In order to maximize the effect of the method of the present invention, it is preferable that 0.70≦2(B+t)/D≦0.90. The basic structure of the method of the present invention is as described above, but in order to fully exhibit the effects of the method of the present invention and from a comprehensive standpoint in industrial implementation, it is preferable to satisfy the following conditions.

First, when making the punch height H variable, what is the width of the punch height adjustment part? However, in the method of the present invention, 0.22≦21.
It is preferable that /2B≦0.42.

Punch height adjustment part width? And punch width? The ratio of 21. /2B is larger, the gap control cost is larger, but 2
L. If /2B becomes large, the radius R1 of the side punch 1 will inevitably become smaller, which will increase the U-forming load and make the straight line part (see Fig. 4b) that is in contact with the side punch 1 and the bottom punch 5 longer. As a result, the roundness of the tube after O-forming deteriorates. Therefore, from the comprehensive standpoint of being able to fully enjoy the effects of the present invention and efficiently molding an excellent vibrator shape, the upper limit value was set at 0.42. Also 2
L. If /2B is less than 0.22, the gap control margin becomes small, so that the effects of the present invention cannot be fully exhibited when steel plates having various thicknesses and strengths are formed into various pipe diameters.

Therefore, the lower limit was set to 0.22. In addition, to maximize the effect of the present invention, 2L/? =0.24~0.
It is more preferable to set it to 40. Next, in the method of the present invention, what is the punch height H or/and punch width? By making H/2B variable, H/2B is adjusted so that the gap amount after O-forming reaches the target value even for materials having a wide range of thickness and strength. In this case, the larger H/2B, the smaller the gap amount. On the other hand, as H/2B becomes smaller, the gap amount becomes larger.

Therefore, when designing a U-punch for carrying out the method of the present invention, it is important to determine to what extent the maximum value (upper limit) and minimum value (lower limit) of H/2B can be adjusted. The inventors conducted a wide range of experiments on steel plates with various thicknesses and strengths, using various punches that satisfy equation (1), and on various pipe diameters, and as a result, found the following. . A. Punch height H or/and punch width?
The punch shape is such that the minimum value (lower limit) of H/2B that can be adjusted by changing is not less than 0.28.

Because, H/? It is possible to increase the gap amount by using a punch shape that allows for a smaller gap, but one of the purposes of the present invention is to obtain an appropriate gap amount, and creating a gap larger than this will reduce the O-forming efficiency. Unfavorable from this point of view. (If you try to reduce the gap amount by changing the O-forming conditions, a large O-forming load will be required.

) Also, the U-punch shape to reduce the minimum value (lower limit) of H/2B that can be adjusted inevitably reduces the radius of the side punch 1, which has the disadvantage of increasing the U-forming load. Unfavorable from the point of view of efficiency. Therefore, from the purpose of the present invention, the minimum value (lower limit) of H/2B
For steel pipes with various dimensions and strengths,
H/2B that can secure the target gap amount by matching the combination of plate thickness, strength, and pipe diameter that minimizes the gap.
From this point of view, the minimum value (lower limit) of H/2B was set to 0.28 as a condition suitable for forming the thick-walled UO steel pipe that is the object of the present invention. Mouth Punch height H or/and punch width? H/ which can be adjusted by changing
The maximum value (upper limit) of 2B is 0.45.

This is because when H/2B exceeds 0.45, the gap amount after O-forming becomes small, making it difficult to secure the target gap amount, and there is almost no gap control allowance for steel pipes with various dimensions and strengths. be.
As mentioned above, the adjustment range of H/2B is the maximum value (upper limit) and minimum value at which the effect of the present invention can be exhibited for the industrial forming of thick-walled UO steel pipes with various dimensions and strengths. (lower limit).

Of course, if the size and strength range of the steel pipe to be formed is narrow, H/
H that can be adjusted by setting the minimum value (lower limit) of 2B to be larger than 0.28 and the maximum value (upper diameter) of H/2B to be smaller than 0.45.
/? It is also possible to make the range smaller. The preferred conditions for maximizing the effect of the present invention for the forming of thick-walled UO steel pipes that are usually carried out are the minimum value (lower limit) and maximum value (upper limit) of adjustable H/2B of 0.30 and 0.30, respectively. The punch shape is 0.43. The shapes of the side punch 1 and bottom punch 5 do not need to be particularly limited as long as they satisfy the above conditions, and as shown in FIG.
2/D may be an arc of 0.2 to 0.35, or a shape having an appropriate curvature may be used.

In addition, in order to obtain a common tangent line between the side punch 1 and the bottom punch 5 even when H/2B is large, both ends of the bottom punch 5 are connected to the radius R of the main part of the bottom punch 5.
Preferably, the radius is smaller than 2. Next, punch height H1 punch width? Regarding how to determine, in advance, the pipe diameter, strength of the material to be formed, plate thickness, 0 forming load, punch width? Then, data on the correlation between the punch height H, etc. and the gap amount δ is determined by experiment or calculation, and based on the above data, the punch height H or /
and punch width? Determine.

Examples of the present invention will be described below.

Figure 5 shows various materials to be formed (steel plates) with different thicknesses and strengths.
After C-forming as usual, U-forming is performed using the U-punch used in the method of the present invention, and then the gap amount δ of the steel pipe after zero-forming and the U-punch height H during U-forming. Show relationships.

The U punch used during U forming has a structure in which the punch height H is variable as shown in FIG. 3, and R1=304.8wn. ．． R
2 = 304.8 gourds (however, radius of both ends = 150mm),
Uni 355.6? ,? =965.277!77! , 2L
．． /2B=0.368 and punch height H is 304.8wt
It has a structure that can be arbitrarily adjusted from 404.8 days (H/?0.316 to 0.419). The O-forming conditions were the same in all cases, and the shape of the steel pipe after O-forming was good in all cases. In addition, when the gap amount δ is negative, there is residual stress that causes the pipe diameter after O-forming to be smaller than the specified pipe diameter. Gap amount δ″ after cutting
was measured and calculated using the formula δ=δ″-30.

As can be seen from FIG. 5, when the punch height H is constant, the gap amount δ varies in the range of 40 to 45 mm depending on various plate thicknesses, strengths, and tube diameters.

Moreover, depending on the punch height H, a positive and negative gap occurs. One of the objects of the present invention is to at least not produce a negative gap over a wide range of plate thicknesses, strengths, and pipe diameters, and to keep the gap amount within a preferable target range for convenience during welding. According to the invention method, the objective can be easily achieved by changing the punch height H and adjusting H/2B so that the target gap amount is achieved. On the other hand, with the conventional method of U-forming using a U-punch with a fixed punch height and adjusting the gap amount by controlling the O-forming conditions, it is difficult to achieve this objective or the O-forming efficiency is It can be easily understood from Table 1 described later that the Table 1 shows a comparison between the conventional method and the method of the present invention in the case where the gap amount is controlled to 7TgL. The thickness, strength, and thickness of the U-punch and formed steel pipe used
The tube diameter is the same as that in FIG. The conventional gap control method is a method in which the O-forming load is controlled, and when it is desired to increase the gap amount, the O-forming load is decreased, and conversely, when the gap amount is desired to be decreased, the O-forming load is increased.

In the conventional method, when H = 304.8 Gourd is fixed and a U punch is used, the target gap amount is secured and the excellent tube shape is satisfied over all the codes A to D. As shown in FIG.
rm), the target gap amount is secured by adding a higher O-forming load, and in this case, the zero-forming efficiency will drop significantly (in other words, a significantly higher O-pressing ability will be required). , code A of the conventional method in Table 1
This can be easily understood by comparing the code A of the method of the present invention. In addition, when using a U punch fixed in the order of H = 364.8 in the conventional method, as shown in Figure 5, when forming with an appropriate O forming load for the tube shape, the symbols A and B are the target. Gap amount (larger than 77077), symbols C and D are smaller than the target gap amount.

Therefore, with codes A and B, the target gap amount and excellent tube shape can be obtained by increasing the O forming load, but
On the other hand, as shown in Table 1, the O forming efficiency is inferior to the method of the present invention. On the other hand, for symbols C and D, it is necessary to widen the gap by lowering the O forming load, but if you try to secure the target gap amount by reducing the O forming load, the O forming load will decrease as shown in Table 1.
The roundness of the tube after forming deteriorates and the tube shape becomes defective, making it impossible to obtain a steel tube that satisfies the specifications, and as a result, codes C and D cannot be formed. Therefore, H=364.8? In the conventional method, not only the applicable range of plate thickness, strength, and pipe diameter is extremely narrow, but also the forming efficiency is poor. As described above, it is clear from Table 1 that in the conventional method, the O-forming efficiency is extremely poor, or it can only be applied to steel pipes with very limited plate thicknesses, strengths, and pipe diameters. On the other hand, in the method of the present invention, as shown in Table 1, the punch height H
By adjusting H/2B by changing the
It becomes possible to easily put it in.

Moreover, the O-forming conditions are fixed to conditions that only take into account the shape of the copper tube after O-forming (that is, an appropriate 0 forming load). Since O
Good roundness of the tube after molding can be obtained, and O-forming efficiency is also good. In addition to the example shown in FIG.
B+t)/D≦0.93, 0.22≦2L. /2B≦0
．． As a result of extensive experiments using various U punches that satisfy the conditions of 42, H/? = H/? if you want to widen the gap within the range of 0.28 to 0.45. It was confirmed that when the gap is narrowed so that H/2B is small, the effect of the present invention can be fully exhibited by controlling the punch height H so that H/2B is large.

In the example, a variable punch was used in which the punch height H could be changed, but the punch width? Even if both of them are made variable, the effects of the present invention can be fully exhibited. In industrial implementation, a structure in which only the panty height H is variable is simple and has good workability. The present invention has been described in detail above, but according to the present invention, the gap amount can be controlled to a desired value very easily for a wide range of plate thicknesses, strengths, and tube diameters, and unlike conventional methods, it is not necessary to change the O forming conditions. Since there is no O molding condition, the 0 molding conditions can be fixed to the most favorable conditions for improving the roundness of the vibrator, so the shape of the vibrator after O molding is also excellent, and the molding efficiency is also good.

Therefore, the industrial value of the present invention is extremely large in the production of thick-walled vibes where the necessity of gap control is extremely important.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view showing an example of the shape of the steel pipe after O-forming, Figure 2
Figures A and b are cross-sectional views showing the conventional U punch shape, Figure 3 is a cross-sectional view showing an example of the U punch used in the method of the present invention, and Figures 4 A and b are U punches used in the method of the present invention. FIG. 5 is a diagram showing the relationship between the punch height H and the gap amount δ of the U punch used in the method of the present invention.

Claims (1)

[Claims] 1. In the UO steel pipe manufacturing process, the punch shape is 0.65
≦2(B+t)/D≦0.93 and using a U punch with variable punch height H or/and punch width 2B, O-forming is performed according to the plate thickness, strength, and pipe diameter of the material to be formed. If the subsequent abutment interval is smaller than the target interval, H/2B is adjusted to a smaller value, and if it is larger than the target interval, H/2B is adjusted to a larger value to achieve the target interval. Or/and after setting the punch width and forming the U
A thick-walled UO steel pipe forming method that is characterized by forming. However, 2B: Punch width (mm), D: Pipe outer diameter (mm)
, t; Thickness of the material to be formed (mm) 2 In the UO steel pipe manufacturing process, the punch shape is 0.65≦2(B+t)/D≦0
．． 93, 0.22≦2L/2B≦0.42 and 0.2
Using a U punch with 8≦H/2B≦0.45 and variable punch height H and/or punch width 2B, the impact after O forming is If the joint spacing is smaller than the target spacing, adjust H/2B by a small amount, and if it is larger than the target spacing, adjust H/2B by a large amount to achieve the target spacing by adjusting the variable punch height or/and A thick-walled UO steel pipe forming method characterized by setting the punch width and performing U-forming and then O-forming. However, 2B: Punch width (mm), D: Pipe outer diameter (mm)
, t: Thickness of the material to be formed (mm), 2L: Punch height adjustment part width (mm), H: Punch height (mm)