KR102334233B1 - Die for forming second preform used in making a weld neck flange and second preform fabricated from the same - Google Patents

Abstract

The present invention is to prevent irregularly-shaped grooves from being formed in the area where the neck and flange parts meet in the process of manufacturing a flange through annular rolling in an annular rolling machine, and is used for hot forming in an annular rolling machine. The secondary preform forming die, which is made in the previous stage of the primary preform, and has a neck, was improved so that a groove for metal supplementation is formed at the point where the inclined surface of the neck forming groove of the die and the surface of the die meet.

Description

Die for forming second preform used in making a weld neck flange and second preform fabricated from the same}

FIELD OF THE INVENTION The present invention relates to a die used to form a secondary preform made as a pre-form of a preform (also called a final preform or a tertiary preform) used in the manufacture of butt weld flanges, and to a secondary preform obtained from the die.

Rapid and continuous transport of fluids is accomplished through pipes. For such transport, a pipe of a certain diameter and length is connected to create a flow path for the fluid, and a flange is generally used to connect the pipe to the pipe. The currently commonly used flange is a slip on welding flange, which is completely inserted into the flange and welded to connect. A socket welding flange, a threaded flange designed to be threaded to connect the inside of the flange and the outside of the tube, and a weld neck flange designed to connect the flange and the tube by butt welding or high hub flange).

Butt weld flanges are used in harsh environments where high temperatures, pressures or stresses are required. As shown in Figure 1, the butt welded flange (1) is a neck (5) and a flange (3) having a bore (7) of the same diameter as the pipe to be connected in the center (neck) (5) and (blade) (3) Is configured, the flange portion (3) is formed with a bolt hole (9) for bolting fastening with another flange (1). The butt welded flange requires a separate process to form a neck, so the manufacturing cost is relatively high.

A butt-welded flange with a small neck with a small bore diameter is manufactured by forging and lathe processing of a round bar. However, a butt-welded flange with a medium or large neck (hereinafter referred to as a flange) is once final dimensions (bore diameter, neck height). , flange part dimensions, etc.) after manufacturing a flange preform (also referred to as a final preform or a tertiary preform) having a smaller dimension by a hot forming method, it is an annular rolling device equipped with a flange part forming roll (main roll) A flange having final dimensions is manufactured through a hot forming (refer to Patent No. 1335651) process in a ring rolling mill, and a machining process. 2 is a cross-sectional view of a tertiary preform (final preform) 16 before being hot-formed in an annular rolling machine. The tertiary preform has an open bore 7' therein with a neck 5' and a flange portion 3 ') is formed so that it is smaller than the final dimension of the flange, but has the main configuration of the flange.

3 is annular rolling of the tertiary preform 16 comprising a pair of shaft rolls 91 and 92 , a mandrel 94 , and a main roll, that is, a flange forming roll 100 . It is a cross-sectional view showing hot forming in a ring rolling mill (90). First, after heating the tertiary preform 16 to an appropriate temperature (for example, typically 1200 to 1250° C. in the case of steel), the flange portion 3' of the tertiary preform 16 is formed by an annular rolling device 90 ) is positioned to be inserted into the forming portion 103 of the flange portion forming roll 100 side, and the mandrel 94 is placed in the bore 7' to perform annular rolling. A pair of shaft rolls 91 and 92 positioned up and down rotate in opposite directions to maintain the preform 16 at a predetermined height, and the mandrel 94 rotates within the bore 7' of the tertiary preform. The preform is pressed outwardly along the perimeter to expand the bore 7' to have a predetermined inner diameter. This pressing of the mandrel 94 simultaneously causes the end of the flange portion 3' of the tertiary preform located in the forming portion 103 of the flange portion forming roll to have an upper surface 106, a lower surface 104 and an inner end. It is expanded to have a width (w) and a height (h) of the molded part 103 made of the lower surface 105 . The flange forming roll 100 is made of alloy steel or carbon steel such as S45C, SCM440, and is coupled to the rotation shaft 99 in a key and keyway coupling method as well known to those skilled in the art. to rotate the preform 16 while rotating.

A flange obtained through annular rolling in an annular rolling machine is formed into a bolt hole by drilling and becomes a flange having final dimensions through finishing (cutting) processing.

The present inventors have found that when manufacturing a flange having a medium-sized neck with a bore diameter of 20 inches or more through annular rolling in the annular rolling apparatus as described above, irregularly shaped grooves are often formed in the area where the neck and the flange part meet. has experienced For example, as shown in FIG. 4 , in the process of manufacturing a flange having a neck having a bore diameter of 26 inches, the portion A1 where the neck and the flange part meet was not smoothly connected, but an irregular shaped groove was formed. . Defective products with such grooves must eventually be discarded, and thus, material loss as well as all material and time effort invested up to this stage are in vain.

SUMMARY OF THE INVENTION It is an object of the present invention to prevent irregularly shaped grooves from being formed in a portion where a neck and a flange part meet in the process of manufacturing a flange through annular rolling in an annular rolling device.

The present applicant has improved the forming die of the secondary preform having a neck and made in the previous stage of the tertiary preform used for hot forming in an annular rolling machine in order to prevent the irregular shape of the grooves from being formed as described above. . That is, the metal supplementary groove was formed at the point where the inclined surface of the neck forming groove of the die and the surface of the die meet. The metal replenishment groove is formed as a rhombic groove having a certain width and height, and the height of the rhombic groove is 2 mm and it is preferable to have a width in the range of 1 to 15 mm.

The secondary preform made from the secondary preform forming die having a metal supplemental groove according to the present invention has projections having a shape corresponding to the metal supplementary grooves, and the metal material corresponding to these projections is hot-formed in an annular rolling machine. It serves to fill the area where the neck and the flange meet, thereby preventing irregular shaped grooves from being formed here.

According to the present invention, in the process of manufacturing a flange through annular rolling in an annular rolling apparatus, the formation of irregularly shaped grooves in the area where the neck and the flange part meet is extremely significantly reduced.

1 is a perspective view of a butt welded flange;
2 is a cross-sectional view of a preform.
3 is a schematic cross-sectional view showing annular rolling of a preform in an annular rolling apparatus.
4 is a cross-sectional photograph of a defective product of the flange manufactured by the annular rolling device.
5 is a schematic diagram of a process for manufacturing a primary preform of a butt-welded flange using a press machine.
6 is a schematic diagram of a process for manufacturing a secondary preform having a neck.
FIG. 7 is a cross-sectional view of a die for forming a neck used in the process of FIG. 6 .
8 is a schematic view showing that the flange portion of the preform is normally formed in the annular rolling apparatus.
9 is a schematic view showing that the flange portion of the preform is abnormally formed in the annular rolling apparatus.
10 is a cross-sectional view of a die for forming a neck used in the present invention and a cross-sectional view of a secondary preform produced from the die.
FIG. 11 is a view corresponding to FIG. 8 , showing that the secondary preform made from the neck forming die shown in FIG. 10 is formed in an annular rolling machine.
12 is a cross-sectional photograph of a flange obtained through annular rolling using the secondary preform made from the neck forming die shown in FIG. 10 .

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

Among the butt welding methods, the preform for a large neck flange is manufactured, as shown in FIG. 5, by first heating a cylindrical base material 10 made of a flange material (low alloy carbon steel, stainless steel, non-ferrous metal, etc.) at a predetermined temperature ( For example, in the case of steel, after heating to 1200 to 1250 ° C.), the primary in the form of a disk having a predetermined thickness by pressing with a press machine 20 composed of a pressure press 22 and a plate-shaped die 24 A preform (12) is made.

Next, as shown in FIG. 6, a primary preform ( 12) to form a neck. To form the neck, first, the plate-shaped die 24 of the press machine 20 is replaced with a die 26 for neck molding, the primary preform 12 is placed thereon, and the primary preform is pressed by the pressure press 22 . The neck forming groove 25 of this neck forming die 26 is filled. As shown in Fig. 7, the neck forming die 26 has a projection 27 in the upper direction formed in its central portion. Next, after positioning the punch 30 on the pressurized primary preform 12, the punch 30 is pressed with a press 22 to form a neck on the primary preform. Next, after removing the punch 30, the primary preform is pressed again with a pressure press 22 to make the flange portion of the primary preform to a predetermined thickness. The secondary preform 14 thus obtained has a neck 5' formed with a bore 7' and a flange portion 3', but the bore 7' is closed by a plate-shaped closure 9. As described above, the closing portion 9 of the secondary preform 14 has a very thin thickness due to the protrusion 27 formed in the central portion of the neck forming die 26 .

The closure 9 of the secondary preform 14 is then punched through to form a tertiary preform 16 having an open bore 7', as shown in FIG. 2 .

The applicant of the present application has found that, for the tertiary preform thus obtained, the flange obtained by performing annular rolling in an annular rolling apparatus as shown in FIG. The causes of irregularly shaped grooves were investigated and studied from various angles.

First, from the fact that the aforementioned irregular grooves occur only in a part of the circumference formed by connecting the neck and flange portions along the neck circumference, the cause of the irregular grooves is due to the non-uniformity of the size of the tertiary preform. guessed Therefore, the size of the various parts of all the tertiary preforms before the operation in the annular rolling device, in particular, as shown in FIG. 2, four linear directions (①, ②, ③, ④), the roundness of the tertiary preform was indirectly measured by measuring the diameter (2R) and calculating the deviation between the maximum value and the minimum value. The measured deviation was around 5% on average, but in severe cases, it exceeded 10% in some cases. In general, the occurrence of the irregular shape of the groove described above occurred when the deviation was on the large side, and when the deviation was small, it did not occur at all. From this, it was determined that the main cause of irregular grooves occurred when the length of the flange portion of the tertiary preform did not match the predetermined length, especially when the length of the flange portion of the tertiary preform was shorter than the normal length, which will be described below. .

Referring to FIG. 8 , the neck 5 ′ and the flange portion 3 ′ of the tertiary preform 16 by the pressurization of the mandrel 94 (see FIG. 3 ) are respectively the inclined surfaces of the flange forming roll 100 . It moves toward the inner end face 105 of the 107 and the molded part 103 (steps (a) and (b)). In the final step (step c), the neck outer surface 6 and the flange portion outer surface 8 of the tertiary preform 16 are formed on the inclined surface 107, the connecting portion 109, the upper surface 106, and the inner side of the forming roll. A flange is obtained with a flange portion of predetermined dimensions while conforming to a corresponding portion of a profile connecting the end face 105 and the lower face 104 . On the other hand, the inner side of the neck 6' of the tertiary preform 16 is gradually made vertical by the pressing of the mandrel 94 (see FIG. 3). In the normal case (when the deviation is small), the neck outer surface 6 and the flange portion outer surface 8 of the tertiary preform 16 are approximately simultaneously the corresponding inclined surface 107 and the inner end surface 105 of the forming roll. meet with

However, when the length of the flange portion 3 ' of the tertiary preform 16 is shorter or longer than the predetermined length (if there is a large deviation), as shown in FIG. 9, other than the neck of the tertiary preform 16 The side surface 6 meets the inclined surface 107 of the flange portion forming roll 100, but the outer surface 8 of the flange portion 3' of the tertiary preform does not yet meet the inner end surface 105 of the flange portion forming roll. When the outer surfaces 6 and 8 of the tertiary preform do not match the profile of the forming roll [Fig. 9(a); When the length of the flange portion of the tertiary preform is short] and the outer surface 8 of the flange portion 3' of the tertiary preform first meets the inner end surface 105 of the flange portion forming roll, and the tertiary preform 16 ) of the neck outer surface 6 does not meet the inclined surface 107 of the flange portion forming roll 100, so that the outer surfaces 6 and 8 of the tertiary preform do not match the profile of the forming roll [Fig. (b); If the length of the flange portion of the tertiary preform is long] occurs. In Fig. 9, which illustrates a case where the outer surfaces 6 and 8 of the tertiary preform do not match the profile of the forming roll, the spacing of the inconsistent portions is exaggerated for explanation. When the length of the flange portion of the tertiary preform is short, the outer surface 8 of the flange portion is formed by the flow of the material constituting the tertiary preform by the pressurization of the mandrel, and the inner end surface 105 of the flange portion forming roll is By moving toward and meeting, the outer surfaces 6 and 8 of the tertiary preform finally come close to the profile of the forming roll, but the metal flow in this vicinity is reduced due to the resistance of the connecting portion 109 of the flanged forming roll and the material Due to the lack of , as shown in FIG. 4 , it is determined that an irregularly shaped groove is formed in the portion A1 where the neck and the flange meet. On the other hand, when the length of the flange portion of the tertiary preform is long, the problem of resistance to metal flow and lack of material by the connection portion 109 will not occur, and therefore the outer surface 6 of the neck is By moving toward and meeting the inclined surface 107 of the flange portion forming roll, the outer surfaces 6 and 8 of the tertiary preform will finally match the profile of the forming roll.

The present applicant determined that it is very important to solve the material deficiency problem from the analysis of the cause of the irregular shape of the groove as described above, and the neck used to form the secondary preform 14 described with reference to FIGS. 6 and 7 . The molding die 26 was improved as shown in FIG. 10 . 10 shows the improved neck forming die 26' and the secondary preform 14' made from the die 26' for convenience of understanding. The improved neck forming die 26 ′ has the same basic internal profile and configuration as the conventional die 26 , such that a projection 27 is formed in the neck forming groove 25 in the upper direction, but the neck forming groove 25 ) differs only in that the metal replenishment groove 40 is formed as shown in the portion where the inclined surface 29 of the die 26' and the surface 28 of the die 26' meet.

The metal replenishment groove 40 moves outward from the point O where the inclined surface 29 of the neck forming groove meets the surface 28 of the die to the point C, and the inclined surface 29 is the surface 28 of the die. The length (width) (L) of the point where the inclined surface 29 and the surface 28 of the die extend in a first straight line 41 parallel to the surface 28 of the die at a point S which is the height H from ) and then extend to a second straight line 43 parallel to the straight line connecting the two points O, S to meet the surface 28 of the die at the point C and form four straight lines 41, 43, straight line OC, straight line OS) has a rhombic shape. Therefore, the metal replenishment groove 40 can further supply the metal material to the material as much as the internal volume of the rhombic-shaped groove 40 having a height (H) and a width (L). Referring to FIG. 10 , the secondary preform 14 ′ manufactured from the improved die 26 ′ has protrusions 40 ′ in a shape corresponding to the metal replenishment groove 40 .

Although the illustrated embodiment shows a rhombic-shaped metal supplementary groove 40 for smooth flow of metal constituting the protrusion 40', other metal supplementary grooves 40 such as a square are also possible.

The size of the irregular grooves occurring at the meeting point (A1) between the neck and the flange of the medium and large flanges tended to increase as the bore diameter increased. This is because the diameter of the flange bore 7 is It was determined that the larger the length and the thickness of the flange portion (3) should be increased proportionally. In addition, it was found that the irregular shape of the groove is locally generated along the circumference of a circle formed by extending the neck and the flange portion meeting the circumference of the neck. Therefore, it was determined that the size of the metal supplementary groove 40 is preferably in the range of 1 to 15 mm according to the diameter of the bore of the flange to be manufactured, the height (H) is 2mm, and the width (L) is 2mm in consideration of these matters. For example, when the bore diameter is 26 inches, the width L is 2 mm, and when the bore diameter is 40 inches, the width L is 7 mm.

11 is a third view on the basis of a secondary preform 14' having protrusions 40' in the shape corresponding to the metal replenishment grooves 40, made from the neck forming die 26' improved as described above. It is a view corresponding to Fig. 8 showing that the flange portion of the preform is formed when the preform 16' is made and hot-formed in an annular rolling machine.

As shown, since the tertiary preform 16' also has the protrusion 40'', even if there is a portion where the length of the flange portion of the tertiary preform as described with reference to FIG. 9 is abnormally short, the protrusion 40 The metal material constituting the '') flows along the circle consisting of the area A1 where the neck and the flange part meet and toward the outer surface of the flange part, while supplying the metal material to the insufficient part. 12 shows a tertiary preform 16' obtained on the basis of a secondary preform 14' manufactured in a die 26' having a metal replenishment groove 40 having a height H and a width W of 2 mm each. This is a cross-sectional photograph of a flange having a bore diameter of 26 inches, manufactured through hot forming in a ring rolling machine using It can be seen that formed by

Although the present invention has been described above with reference to the accompanying drawings, those skilled in the art to which the present invention pertains will appreciate that various modifications are possible within the scope of the present invention described in the claims to be described later. For example, the present invention can be applied to all types of neck forming dies used for manufacturing the secondary preform, such as when the protrusion 27 in the upper direction is not formed in the neck forming groove 25 .

1st preform; 12 2nd preform : 14,14' 3rd preform : 16,16'
Press: 20 Press press: 22 Plate die: 24
Die for neck shaping: 26, 26' Neck shaping stitch: 30, groove for metal supplementation: 40
Annular rolling machine: 90 Axial roll: 91,92 Mandrel: 94
Rotational shaft: 99 Flange forming roll: 100 Forming part of flanged forming roll: 103

Claims (4)

A tertiary preform 16 having an open bore 7' formed neck 7' and a flange portion 3' is hot-formed in an annular rolling machine, medium and large butt welding with a bore diameter of 20 inches or more When manufacturing the expression flange, the molding of the secondary preform 14 having the neck 5' and the flange portion 3' formed in the previous step of the tertiary preform 16 and having the closed bore 7' formed therein. In the die,
A tertiary preform obtained by opening a bore of the secondary preform at a portion where the inclined surface 29 of the neck forming groove 25 of the secondary preform forming die and the surface 28 of the forming die meet is hot in the annular rolling machine A secondary preform forming die (26') for manufacturing a butt-welded flange, characterized in that a metal supplementary groove (40) is formed for providing a metal flowing by hot rolling during forming. The secondary preform forming die for manufacturing a butt weld type flange according to claim 1, wherein the groove (40) is formed as a rhombic groove having a constant width and height. The secondary preform forming die for manufacturing a butt-welded flange according to claim 2, wherein the height of the rhombic groove is 2 mm and the width is in the range of 1 to 15 mm. 4. Made from a secondary preform forming die (26') for manufacturing a butt-welded flange according to any one of claims 1 to 3, characterized in that it has a projection (40') of a shape corresponding to the metal supplementary groove (40) Second preform.

Images