KR101744840B1

KR101744840B1 - Hydroforming process for tube

Info

Publication number: KR101744840B1
Application number: KR1020150149396A
Authority: KR
Inventors: 이병호; 임창준; 강대건; 이호진; 유영훈
Original assignee: 세종공업 주식회사; (주)탈리스
Priority date: 2015-10-27
Filing date: 2015-10-27
Publication date: 2017-06-09
Also published as: KR20170048826A

Abstract

The present invention provides a tubular hydraulic pressure molding method comprising: a first step of providing an upper molding plate on which a concave-convex part is formed and a lower molding plate on which concave and convex parts are formed, on an upper surface of a lower mold; A second step of placing the tube material on the lower mold; A third step of injecting high-pressure water into the tubular member and sealing both longitudinal ends of the tubular member; And a fourth step of lowering the upper mold so that the upper molding plate and the lower molding plate are pressed onto the outer surface of the tube, and bending and surface processing the tube. According to the present invention, it is possible to prevent the occurrence of wrinkles on the bending portion by bending the pipe material in a state in which the high-pressure compressed water is filled in the pipe material, and the bending and surface processing The productivity can be improved and the defect rate can be reduced.

Description

Hydroforming process for tube < RTI ID = 0.0 >

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a hydraulic pressure molding method for subjecting a pipe material to plastic working in a state where high-pressure compressed water is injected into the pipe material, and more particularly, to a pipe pressure hydraulic molding method in which bending and surface machining are simultaneously performed.

In the modern industry, in which the industry is continuously developing, product cycles are getting shorter due to diversification of consumers' purchasing preferences and the trend of smaller and larger variety of industrial structure. In order to cope with this, the industrial field has been steadily pursuing automation of the process.

On the other hand, it should be noted that the automation process must consider and reflect factors such as the speedy work process, process precision and product quality improvement. In recent years, due to the increase in income of such consumers and the development of various products, the industrial customs are also increasing and becoming larger.

Further, in order to secure the supply amount in accordance with the demand amount of the pipe as described above, it is necessary to shorten the time required for the manufacturing process, and in order to do so, automation of the related process is essential. Until recently, however, the milling work has mostly been done by hand.

Generally, the tube is manufactured by welding a metal sheet of a predetermined thickness by welding at the end, and may be used in a straight shape or in a curved shape by bending or curving the stop at a certain curvature. At this time, when bending the tube by simple pressing, wrinkles are generated or collapsed at the bending portion, and when the tube has a small curvature, the bending angle is not accurate and the bending surface is not smooth.

In order to solve such a problem, a hydroforming method has been proposed in which the pipe is bended while filling a high-pressure compressed water in the pipe. However, since the conventional hydroforming method merely bends the tube and does not form a concave or convex pattern on the tube, a separate plastic working step for machining the tube surface has to be additionally performed. In this way, If the processing is separately performed, not only the productivity is lowered but also it is difficult to precisely select the pattern forming position, which is disadvantageous in that the product defects increase.

KR 10-2011-0138705 A

SUMMARY OF THE INVENTION The present invention has been proposed in order to solve the above problems and it is an object of the present invention to prevent bending of the bending portion by bending the bending portion in a state where the high pressure water is filled in the bending portion, The present invention has been made in view of the above problems, and it is an object of the present invention to provide a tubular fluid pressure molding method capable of improving the productivity and reducing the defective rate.

According to another aspect of the present invention, there is provided a tubular hydraulic pressure molding method comprising the steps of: providing an upper molding plate having a concavo-convex portion on a bottom surface of an upper mold and installing a lower molding plate on which concave- ; A second step of placing the tube material on the lower mold; A third step of injecting high-pressure water into the tubular member and sealing both longitudinal ends of the tubular member; And a fourth step of lowering the upper mold so that the upper molding plate and the lower molding plate are pressed onto the outer surface of the tube, and bending and surface processing the tube.

The lower molding plate and the upper molding plate are each formed in a semicylindrical shape having a semicircular cross section so as to cover the entire one outer side of the tube,

In the fourth step, when the upper mold is lowered as much as possible and the width direction ends of the lower molding plate and the upper molding plate are brought into contact with each other, the lower molding plate and the upper molding plate are formed into a single pipe shape bent or curved do.

The tubular member is manufactured through a process of welding one end of a metal plate material and the second step is configured to place the tubular material on the lower mold so that the welding line of the tubular material is laterally directed.

The third step is constituted so as to seal the longitudinal direction of the pipe member by punching the punches at both ends in the longitudinal direction of the pipe member after injecting the high-pressure water into the pipe member.

The fourth step is configured to move the punch toward the pipe material in accordance with the descending speed of the upper mold after the upper pipe material is in contact with the pipe material.

The lower mold and the upper mold are formed in a shape of 'U' downward bending the interruption of the tube, and the fourth step is set to move the punch at the same speed as the lowering speed of the upper mold .

A fifth step of cutting the pipe material having completed bending and surface processing, and a sixth step of expanding both ends in the longitudinal direction of the pipe material.

According to the present invention, it is possible to prevent the occurrence of wrinkles on the bending portion by bending the pipe material in a state in which the high-pressure compressed water is filled in the pipe material, and the bending and surface processing The productivity can be improved and the defect rate can be reduced.

Fig. 1 is a flowchart of a tubular hydraulic press forming method according to the present invention.
2 is a side view of a hydroforming apparatus for implementing a tubular hydraulic pressure molding method according to the present invention.
3 is an exploded perspective view of the lower molding plate and the upper molding plate.
FIGS. 4 to 6 sequentially illustrate the process of forming the pipe by the pipe hydroforming process according to the present invention.
Fig. 7 shows a process of cutting the bending and surface-finished tubing.
Fig. 8 shows a process of expanding both ends of the cut pipe.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a hydraulic hydroforming method according to the present invention will be described in detail with reference to the accompanying drawings.

2 is a side view of a hydroforming apparatus for implementing a hydraulic hydroforming method according to the present invention, and Fig. 3 is an exploded perspective view of a lower molding plate and an upper molding plate. Fig. And FIGS. 4 to 6 sequentially illustrate the process of forming the tube by the tube hydroforming method according to the present invention.

The tube hydroforming method according to the present invention is a kind of plastic working method in which the tube 10 is pressed and bended, The bending of the tube 10 is performed in a state in which high-pressure compressed water is injected into the tube 10 so that the tube 10 can be kept constant, The most important feature is that it becomes.

2, the upper mold plate 220 having the concave and convex portions 240 is disposed on the bottom surface of the upper mold 120, and the concave and convex portions 240 are formed A first step S10 of placing the lower molding plate 210 on the upper surface of the lower mold 110 and a second step of placing the tube 10 on the lower mold 110 as shown in FIG. A third step S30 of sealing the lengthwise ends of the tube 10 as shown in FIG. 5 after the high pressure water is injected into the tube 10, And a fourth step of bending and machining the tube 10 by lowering the upper mold 120 as shown in FIG. 6 so that the lower tube 210 and the lower tube 210 are pressed against the outer surface of the tube 10 S40).

At least one concave portion 240 is formed on the upper surface of the lower molding plate 210 and the lower surface of the upper molding plate 220 so that the tube 10 is inserted between the lower mold 110 and the upper mold 120 The surface of the tube 10 to be pressed against the lower molding plate 210 and the upper molding plate 220 is pressed against the concave and convex portions 240 of the lower molding plate 210 and the upper molding plate 220 A pattern to be formed is formed. The bending of the tube 10 can be performed by one operation of lowering the upper mold 120 while the tube 10 is placed on the lower mold 110. In this way, And surface processing are performed all at once, which is advantageous in that the productivity is remarkably improved.

When the surface of the tube 10 is bent by the plastic forming method, a separate mold having the concave-convex portion should be pressed against the outer surface of the tube 10. The same lower and upper molds 110, Even if the bending of the tube 10 is performed by bending the tube 10 with a predetermined angle, the bending angle of the tube 10 having the bending process may be finely distorted, This becomes very difficult. If the metal mold having the concavities and convexities is not brought into close contact with the outer surface of the tube 10 accurately, the surface can not be precisely machined, thereby increasing the defective rate.

However, when the upper mold 120 is lowered in order to bend the tube 10, the lower molding plate 210 and the upper molding plate 220 are entirely inserted into the tube 10, And the pattern corresponding to the concave and convex portions 240 is formed at a precise position on the surface of the tube member 10, that is, the defective rate is hardly generated.

When the pattern to be formed on the surface of the tube 10 is positioned only on the upper and lower surfaces of the tube 10, the lower and upper plates 210 and 220 are brought into close contact with only the upper and lower surfaces of the tube 10, Lt; / RTI > When the lower molding plate 210 and the upper molding plate 220 are in close contact with only the upper and lower surfaces of the tube 10, The untouched surface bulges and the overall shape of the tube 10 can be abnormally deformed.

3, each of the lower molding plate 210 and the upper molding plate 220 may have a semi-cylindrical shape having a semicircular cross section, . When the lower mold plate 210 and the upper mold plate 220 are each formed into a semi-cylindrical shape, the upper mold 120 is lowered as much as possible in the fourth step, The lower molding plate 210 and the upper molding plate 220 form a single pipe shape bent or curved when the width direction ends of the lower molding plate 210 and the upper molding plate 220 are in contact with each other, The pipe 10 to be hydroformed between the forming plates 220 can be kept circular in cross section even if bent or curved.

On the other hand, when the interruption of the tube 10 is downwardly pressed and bent or curved, compressive stress is generated on the upper surface of the tube 10, and tensile stress is generated on the bottom of the tube. In this case, the tube 10 is generally manufactured through a process of welding one end of the metal sheet to the end. When the tube 10 is seated on the lower mold 110 so that the welding line of the tube 10 is positioned at the upper side A phenomenon may occur that the welding line is folded or twisted in the process of pressing down the interruption of the tube 10 to downward. In contrast, when the tube 10 is seated on the lower mold 110 so that the welding line of the tube 10 is positioned at the lower side, the welding line may be broken in the process of pressing the tube 10 downward have.

Therefore, when the tube 10 is placed on the lower mold 110 in the second step, it is preferable to adjust the direction of the tube 10 so that the welding line of the tube 10 faces the side. Since the compressive stress or tensile stress is not generated on the right and left sides of the tube 10 when the interruption of the tube 10 is downwardly pressed, when the welding line of the tube 10 is arranged to be laterally directed as described above, It is possible to prevent the line from being ruptured or broken.

After the seating of the tube 10 is completed, high-pressure water is injected into the tube 10, and then the punches 310 are respectively pressed to both ends in the longitudinal direction of the tube 10 as shown in FIG. 5, The punch 310 is in close contact with both longitudinal ends of the pipe 10 so that the compressed water in the pipe 10 can not flow out to the outside, A part of the end of the punch 310 may be inserted into the tube 10 in a fitting manner so that the pressure of the compressed water in the tube 10 can be further increased. When a part of the end of the punch 310 is press-fitted into the pipe 10 as described above, not only the pressure of the compressed water inside the pipe 10 is increased but also the sealing property of both ends of the pipe 10 in the longitudinal direction is improved Effect can also be obtained. Although the pair of punches 310 are conveyed by the feeding cylinder 320 in the present embodiment, the pair of punches 310 may be conveyed by various kinds of conveying means other than the feeding cylinder 320 Lt; / RTI >

When the tube 10 is sealed at both ends in the longitudinal direction, the upper mold 120 is lowered to bend the tube 10 in accordance with the shapes of the lower mold 110 and the upper mold 120. The lower mold 110 may be raised and the upper mold 120 may be lowered. However, when the lower mold 110 and the upper mold 120 are both raised and lowered, the tube 10 mounted on the lower mold 110, The machining precision is lowered and the driving part for lifting and lowering the lower mold 110 and the upper mold 120 must be separately provided. Therefore, it is preferable that the lower mold 110 is fixed and only the upper mold 120 is set to be raised and lowered.

On the other hand, when the end of the tube 10 is bent while the both ends of the tube 10 are fixed, the total length of the tube 10 is increased, and the diameter of the tube 10 is reduced. As the diameter of the tube 10 is reduced, the surface of the tube 10 is not brought into close contact with the lower molding plate 210 and the upper molding plate 220, so that the surface of the tube 10 is not normally processed .

Therefore, in the tubular hydraulic press forming method according to the present invention, in order to prevent the phenomenon that the total length of the tubular member 10 increases and the diameter of the tubular member 10 decrease, even if the tubular member 10 is bent, It is preferable that the pair of feeding cylinders 320 gradually push both ends of the tube 10 when the upper mold 120 is lowered. That is, after the upper forming plate 220 contacts the tube 10, the pair of feeding cylinders 320 are moved in a direction corresponding to the lowering speed of the upper mold 120, (10). &Lt; / RTI >

When the punch 310 supporting both longitudinal ends of the pipe 10 is moved in the direction of compressing the pipe 10 during the bending process of the pipe 10, the reduction of the diameter of the pipe 10 is prevented, The surface of the tube 10 can be pressed onto the lower molding plate 210 and the upper molding plate 220 so that the surface of the tube 10 can be normally processed. If the maximum outer diameter of the punch 310 is set larger than the outer diameter of the tube 10, the punch 310 can not be smoothly transferred horizontally between the lower mold 110 and the upper mold 120, It is preferable that the maximum outer diameter of the tubular member 310 is set equal to the outer diameter of the tubular member 10.

When the upper mold 120 and the upper mold 120 are constructed to be bent downward in a U shape as shown in the present embodiment, The length of the tube 10 is increased by 20 cm when both ends in the longitudinal direction of the tube 10 are fixed when the tube 10 is lowered by 10 cm in a state of being in contact with the pair of feeding cylinders 10, It is preferable that each of the lengthwise ends of the tube 10 is pressed by 10 cm each. That is, the descending speed of the upper mold 120 and the moving speed of the punch 310 are preferably set to be the same.

The present invention also relates to a method of manufacturing a bushing and / or a bushing to obtain a plurality of parts from a single bushing and surface-processed tube 10 through the first to the fourth steps (S10 to S40) A fifth step (S50) of cutting the surface-processed tubing 10 and a sixth step (S60) of expanding both ends in the longitudinal direction of the tubing 10 may be further included. The fifth step S50 for cutting the tube 10 and the sixth step S60 for expanding the tube 10 will be described below in detail with reference to FIGS. 7 and 8. FIG.

Fig. 7 shows a process of cutting the bending and surface-finished tube 10, and Fig. 8 shows a process of expanding both ends of the cut tube 10.

Using the tubular hydroforming method according to the present invention, a pipe 10 having a downwardly bent U-shape at its center portion as shown in FIG. 7 can be obtained. 8, a step of cutting the interruption of the tube 10 using a separate cutter 400 is added as shown in FIG. 7, when the final required parts are different in height in the longitudinal direction as shown in FIG. 8 .

7 may be modified by changing the shapes of the lower mold 110 and the lower mold 110. However, it is also possible to bend the straight pipe 10 in the form shown in FIG. 7, It is necessary to lower the punch 310 that hermetically seals one end in the longitudinal direction of the pipe 10 in order to bend the punch 310. In addition to the feeding cylinder 320 for transporting the punch 310 in the horizontal direction, There is a problem that a separate conveying means for raising and lowering the conveying path is required.

Therefore, in order to obtain the tubular member 10 having different lengths in the longitudinal direction, the tubular member 10 is bent so that the middle portion of the tubular member 10 is lowered as shown in the present embodiment, Cutting is preferred.

Further, in order to mount the tube 10 'cut by the cutter 400 to another flow path, a step of expanding both longitudinal ends of the tube 10' may be added. At this time, the method of expanding both ends in the longitudinal direction of the tube 10 'is widely commercialized in various ways in the technical field of the present invention, and a detailed description of the process of expanding the tube 10' is omitted .

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the scope of the present invention is not limited to the disclosed exemplary embodiments. It will also be appreciated that many modifications and variations will be apparent to those skilled in the art without departing from the scope of the invention.

10: pipe member 110: lower mold
120: upper mold 210: lower molding plate
220: upper molding plate 240: concave and convex portion
310: Punch 320: Feeding cylinder
400: cutter

Claims

A first step of providing an upper molding plate on which a concave-convex part is formed and a lower molding plate on which concave and convex parts are formed, on the upper surface of the lower mold;
A second step of placing the tube material on the lower mold;
A third step of injecting high-pressure water into the tube and then sealing the lengthwise direction of the tube by pressing the punches at both ends in the longitudinal direction of the tube; And
A fourth step of lowering the upper mold so that the upper molding plate and the lower molding plate are pressed onto the outer surface of the tube to bend and surface-process the tube;
A fifth step of cutting the pipe material having completed bending and surface processing;
A sixth step of expanding both longitudinal ends of the pipe material;
, &Lt; / RTI &
The lower mold and the upper mold are formed in such a manner as to downward bend the U-shaped break of the tube,
Wherein the fourth step is set to move the punch at the same speed as the descending speed of the upper mold.

The method according to claim 1,
The lower molding plate and the upper molding plate are each formed in a semicylindrical shape having a semicircular cross section so as to cover the entire one outer side of the tube,
In the fourth step, when the upper mold is lowered as much as possible and the end portions in the width direction of the lower molding plate and the upper molding plate come into contact with each other, the lower molding plate and the upper molding plate are bent Wherein the method comprises the steps of:

The method of claim 2,
The pipe is manufactured through a process of rolling one metal plate and welding the ends thereof,
Wherein the second step is configured to seat the pipe material on the lower mold so that the welding line of the pipe material is laterally directed.

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