JP5649226B2 - Different diameter pipe manufacturing method and different diameter pipe manufacturing apparatus - Google Patents

Description

  The present invention relates to a method for manufacturing a different diameter pipe, in which a different diameter pipe having an enlarged diameter portion at an end is manufactured by bending.

  An exhaust pipe used in an engine exhaust system, in particular, a silencer, requires a degree of design freedom in terms of parameters such as the inner diameter and length of the pipe in order to achieve both noise reduction performance and ventilation resistance. Therefore, a method of manufacturing a pipe corresponding to an arbitrary specification is often employed from a steel plate by using a bending process such as UO bending process or roll bending process instead of using an existing pipe material. In order to improve the noise reduction performance, a punching pipe with a small diameter hole punched on the pipe surface may be used. In this case, the punching pipe is manufactured by punching in the state of a steel plate and then bending. Done.

The exhaust pipe used in the silencer has a small pressure difference between the inside and outside of the pipe, and even if a gas leaks, leakage to the outside air is blocked by the shell of the outer shell, so that the air tightness is not so required. Therefore, the butt portion after bending is often spot-welded only from the minimum necessary number in terms of productivity. However, when manufacturing different diameter pipes with one diameter at the end of the pipe being larger than the basic diameter by bending, if the butt part of the pipe expansion part is not sufficiently joined, the material will be insufficient at the time of pipe expansion molding. There is a problem that a gap is generated at the portion.

In order to avoid this problem, the first method is to weld the butt over almost the entire length and then perform tube expansion. In this case, in order to enable welding over the entire length, as shown in FIG. 10, an extension portion called a tab is set at the end portion, and a method of cutting after welding is employed, resulting in waste of materials and processes. In addition, after pipe forming by bending, welding is performed and pipe expansion is performed, so that a waste of the process of going back and forth between the pressing process and the welding process occurs.
As a second method, as shown in FIG. 11, an extra material called an ear is provided in the portion corresponding to the expanded portion of the steel plate of the material, and a gap is generated in the butt portion of the expanded portion even when the expanded tube is processed. A way to avoid it is taken.
In other words, according to the current technology, when manufacturing a different diameter pipe whose end is expanded by any method by bending, a deformed blank with a portion called a tab or ear is required, and the material Part of the material has to be scrapped, resulting in a deterioration in material yield and an increase in processing man-hours.

  As the prior art disclosed in the patent document, as shown in FIG. 8, a technical disclosure about UO bending of a tapered pipe having a different diameter can be seen. There is no prior art related to manufacturing by bending.

Japanese Patent No. 4263991

  The present invention was made in order to solve the problems of the present state of the art, and efficiently bent a different diameter pipe having an enlarged diameter portion at one of its ends with less steps without wasting material. It aims at providing the method of manufacturing by.

According to the first aspect of the present invention, a pipe having an enlarged diameter portion at one end of the pipe is manufactured by a blanking process of cutting a steel plate into a predetermined dimension and a bending process of forming the blank material into a tubular shape by bending. In the blank step, the portion to be the diameter-expanded portion is set in advance in the direction to be the circumferential direction, the stretching step is set in advance, the stretching step in the cross section including the stretching direction and perpendicular to the steel plate, Only the both ends are molded into a corrugated shape, and in the subsequent bending process, the stretched portion is molded into a predetermined tube-expanded shape by bending with U 2 O continuous bending . As a result, even when the butt portion is not joined in advance at the expanded portion, or even when only a part is joined by spot welding, there is no problem that a gap is generated due to insufficient material of the part.

Moreover, the said extending | stretching process was made to shape | mold only a both-ends part in a corrugated shape in the cross section perpendicular | vertical to a steel plate including an extending | stretching direction. Thereby, the material can be stretched with a simple mold structure, and the trace of molding in the stretching process remaining in the product after the bending process is completed can be minimized.

In addition, the bending process is performed by bending by UO continuous bending. As a result, a single die having a relatively simple structure can be bent in a single process, so that the die cost can be reduced and the processing time can be reduced.

Invention of Claim 2 is invention regarding the technique which manufactures the punching pipe which has many pores on the surface by the technique which concerns on this invention. In addition to the requirements of claim 1, the corrugated molding pitch is synchronized with the punching hole processing pitch, and the corrugated molding and the punching are performed simultaneously. By performing punching processing carried out in the original separate step to stretching simultaneously with a reduction in die cost without new step occurs, the time required for machining can be realized.

A third aspect of the present invention is an invention relating to a mold structure used in the pipe manufacturing method according to the first or second aspect. The mold structure is characterized in that the bending step is configured such that bending by UO continuous bending and tube expansion are performed simultaneously. As a result, the die cost can be reduced and the machining time can be shortened.

The effects of using the above means are as follows.
First of all, the effect of extending the blank in the blanking process is that there is no need to take a method of expanding the tube after welding the entire length of the butt, and an extension called so-called tab is added to the terminal part to cut off after welding. There is no need to take this method. As a result, the material shown in FIG. 10 is not wasted, and it is not necessary to weld the entire length. Therefore, various types of welding such as spot welding can be employed, and the efficiency of the process can be improved.
Further, even when compared with a method in which an extra material called an ear is provided in a portion corresponding to the expanded portion of the steel plate of the material, there is no waste of the material as shown in FIG. Cost increases can also be avoided.
Then applying a distraction processing only the both end portions of the material, and as the effect of the stretched shape corrugated, it is possible to perform the material stretching in a simple mold structure, remains in the product after the bending process completion Traces of molding in the stretching process can be minimized.
In addition, when applied to pipes with punched holes, by synchronizing the corrugated molding pitch and punching hole processing pitch, the corrugated molding and punching can be performed simultaneously, reducing die costs. And the processing time can be shortened.
In addition, since the bending process is performed by UO continuous bending, it is possible to mold a pipe with a relatively simple structure and in one process, thereby reducing the cost of the mold and the processing time.

The process at the time of extending | stretching a whole pipe expansion site | part is illustrated, (1a) shows a state after a extending process, (1b) after a bending and a pipe expanding process, (1c) shows the state after a welding process. The state after the extending | stretching process based on invention of Claim 1 is illustrated. The punching pipe manufacturing process when extending | stretching is applied to the whole pipe expansion site | part is illustrated, (3a) is after a extending process, (3b) is after a bending process, (3c) shows the state after a welding process. The drawing shows the change in the material in the stretching, punching, and blanking process when the stretching process is applied to the entire expanded portion . In the invention according to claim 2, the change of the material in the drawing, punching, and blank process when the corrugation is performed only at both ends and the punching is performed is illustrated. The drawing shows the change of the material in the stretching / punching process for each pitch when the stretching process is applied to the entire expanded portion . The state at the time of blank material (sheet material) injection | throwing-up is illustrated in the UO continuous bending processing apparatus which concerns on this invention. The UO continuous bending apparatus according to the present invention is illustrated after U bending and before O bending. The state after O bending is illustrated about the UO continuous bending apparatus which concerns on this invention. The process of the manufacturing method of the 1st different diameter pipe in the past is illustrated. The process of the manufacturing method of the 2nd different diameter pipe in the past is illustrated. The prior art which concerns on the patent 4263991 is illustrated.

1 Blank material (sheet material)
2 Stretched part 3 Butt part 5 Blank material (sheet material)
6 punching portion 8 hoop material 10 UO continuous bending machine 11 upper mold holder 12 lower mold holder 13 O bending die 14 U bending die 15 core metal 16 core metal holder 17 material positioning 18 gas spring 19 spring 21 tab 20 core metal diameter expansion Part 22 Ear

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a process diagram illustrating a method for producing a different diameter pipe when a drawing process is applied to the entire expanded portion .
(1) Preparation process of blank material In FIG. 1, 1a shows the state which extended | stretched from the board | plate material or the hoop material, and was shape | molded in the blank material of the predetermined | prescribed shape. As shown in FIG. 4, for example, the blank material preparation step can be performed by a progressive press. FIG. 4 shows an example of a process including a punching process. In the case of a normal different diameter pipe, a stretching process for stretching a diameter-enlarged portion along the feed direction with respect to the hoop material 8 and a blank process for cutting into a predetermined shape are sequentially performed. By carrying out the construction, a predetermined blank material shown in 1a is molded. Thereby, a blank material can be manufactured efficiently.

As shown in Fig. 1a, the stretching process is a process of stretching the material in the direction that should become the circumferential direction after UO continuous bending, and preferably the mold is designed so that it becomes a corrugated shape after the cross section in the stretching direction. To do. The purpose is to pre-stretch the length of the stretched material in accordance with the circumference of the expanded diameter part, and the unevenness should be as gentle and regular as possible so that the stretched shape does not remain after UO continuous bending. It is a requirement to stretch the film. Therefore, the mold should be designed so that the material length after processing in the stretching direction is substantially the same as the peripheral length after completion of the expanded diameter portion, and the R of the corrugated corner portion of the corrugated shape is as large as possible. It is desirable.

FIG. 5 shows a process in the case where the drawing process is performed only on both ends of the enlarged diameter portion. In order to minimize the trace due to the stretching process after the bending process as in the invention according to the first aspect , the corrugated process can be performed only at both end portions close to the butt portion, and the central portion can be omitted. This is because the central portion can obtain the same effect as the stretching process at the same time as the bending process by the drawing effect. In this case, as shown in FIG. 2, the blank material after stretching is in a state in which the material is preliminarily extended by corrugated processing only at both ends that become butt portions during tube forming.

(2) U bending process Next, the blank material 5 (sheet material) is put into the UO continuous bending apparatus shown in FIG. The processing apparatus includes an upper mold holder 11 fixed to a slide (not shown) of a press apparatus (not shown), a lower mold holder 12 fixed to a bolster (not shown), and an upper mold holder 11. O-bending die 13, U-bending die 14 fixed to lower mold holder 12, material positioning 17 fixed to both sides of U-bending die 14, and a pair of gas springs fixed to upper mold holder 11 18, a metal core holder 16 supported by a spring 19 fixed to the lower mold holder 12, and a metal core 15 held by the metal core holder 16.
FIG. 7 shows a state in which the blank material is put into the UO continuous bending apparatus and the press apparatus is near top dead center.

Next, the operation from the time of sheet feeding shown in FIG. 7 to the time of completion of the U-bending shown in FIG. 8 will be described below.
In the U-bending step, the gas spring 18 presses the blank material 5 against the U-bending die 14 through the core bar 15 to perform press molding into a U-shape. Specifically, the following operations are performed.
When the press device is near the top dead center, the mandrel 15 is held in a cantilevered state by the mandrel holder 16, so the blank material 5 is put into the press device through the gap between the U-bending dies 14 and 7b. As shown, the material positioning 17 is arranged at a predetermined position on the U-bending die 14. When the press device starts to descend from the top dead center, the pair of gas springs 18 fixed together with the lower of the upper die holder 11 descends and comes into contact with the opposite ends of the core metal holder 16 and the core metal 15 on the opposite side of the core metal holder. Then, the core metal 15 starts to be reduced. Thereafter, the metal core 15 presses the blank material 5 against the U-bending die 14. The U-bending process is completed when the core metal 15, the blank material 5, and the U-bending die 14 are brought into close contact with each other. However, since the core metal 15 is pressed by the gas spring 18, the upper mold holder 11 is further lowered. The core metal 15 maintains the state in which the blank material 5 is pressed against the U-bending die 14 with a predetermined pressure and is in close contact therewith. This state is shown in FIG.

On the other hand, the blank portion 5 is formed into a predetermined tube-expanded shape between the core-bar expanded portion 20 and the corresponding expanded U-bending die 14. Due to the effect of being stretched in advance to a length equivalent to the length after molding, the processing is smoothly performed without generating cracks. Also, since the prior corrugation is molded with a large R, traces of corrugation after U bending can be minimized.
Further, in the case where the stretching process is performed only on both ends as in the invention according to the first aspect , in the U-bending process, a portion that has not been stretched is expanded. Also in this case, it is possible to form into a predetermined tube-expanded shape without generating cracks or the like due to the effect of drawing by designing an appropriate mold.

(3) O bending process When the press device continues to move downward, the lower end of the O bending die 13 fixed to the upper mold holder 11 presses the upper end of the U-shaped workpiece from above, and starts molding. The lower part of the bending die 13 has a semicircular shape corresponding to the shape of the upper half of the pipe in a cross section perpendicular to the axis, and a square shape that sandwiches the workpiece on both sides. Due to these effects, when a pair of upper ends of the U-shaped workpiece are bent in directions close to each other, and the three of the core metal 15, the blank material 2, and the O bending die 13 are brought into close contact with each other, the half of the O bending die 13 is The workpiece is molded into a cylindrical shape between the circular portion and the cored bar 15, and both ends of the workpiece are brought together, and the O bending process is completed.

  On the other hand, the expanded pipe portion is bent in a direction in which both end portions of the workpiece are close to each other between the core metal expanded diameter portion 20 and the corresponding expanded O-bending die 13, and formed into a semi-cylindrical shape of the expanded tube. Normally, it is not possible to obtain a drawing effect at the end of the workpiece, so when UO bending is performed, the material of the butt portion is insufficient in the enlarged diameter portion, resulting in a gap, but in this plan, the length equivalent to the length after molding by drawing in advance. In addition, since the material is stretched, no gap is generated in the butt portion even after the pipe expansion process.

(4) Discharge process of workpiece After that, the press device passes the bottom dead center and starts the ascending operation. When the upper mold holder 11 is raised and close to the top dead center, the gas spring 18 that is in contact with the end of the core bar 15 opposite to the core bar holder of the core bar 15 is isolated, and the core bar 15 is separated from the core bar holder 16. And is supported in the middle of the O-bending die 13 and the U-bending die 14. A sufficient space is secured between the pipes of the upper workpiece wound around both dies and the core metal 15, and the diameter of the workpiece is reduced in the opposite direction to the core metal, so that it is opposite to the core metal. The work can be discharged manually or by a discharge device.

(5) Welding process of abutting part This process is a process of joining the abutting part 3 of the workpiece that has been abutted by the O bending process by brazing or welding. Due to the effect of the stretching process, the enlarged diameter portion is also in close contact with no gap, so various welding methods including laser welding can be employed. For pipes that do not require airtightness, a minimum number of points can be welded by spot welding and brazing, and solvent and energy consumption related to welding can be suppressed.
Specifically, joining is performed by brazing or welding the attachment part 3 of the workpiece mounted on the jig by a human hand or a welding robot.

The different diameter pipe manufacturing method having punching holes according to the invention of claim 2 differs from the above method only in the process until the blank material is manufactured, and the UO continuous bending process is substantially the same, so only the manufacturing process of the blank material will be described. .
This proposal is used, for example, for manufacturing a filter pipe which is arranged inside a silencer and has a large number of pores on the surface of the pipe used for exhaust sound attenuation.
In this proposal, as shown in FIG. 6, for example, by correlating eight rows of punching holes with one pitch of corrugation and synchronizing the arrangement, corrugation and punching can be performed simultaneously with one mold, and the size is small. A large area can be processed with a mold. Specifically, the blank material as the material of the filter pipe can be efficiently processed by shifting the hoop material by one pitch and processing it a predetermined number of times.
The blank material 5 is formed by performing predetermined wave forming / punching by the progressive processing and sequentially performing blank processing for forming into a predetermined shape as shown in FIG.
Producing different diameter pipe by UO successive bending steps described in the following examples according to claim 1. FIG. 3 shows a state 3a after blanking, a state 3b after bending, and a state 3c after welding.

In addition, the different diameter pipe manufacturing method which concerns on this construction method is applicable to various gas and liquid piping, without being limited to application in an exhaust pipe.

Claims (3)

A pipe manufacturing method for manufacturing a pipe having an enlarged diameter part on one end of a pipe by a blank process of cutting a steel plate into a predetermined dimension and a bending process of forming the blank material into a tubular shape by bending,
The blank process has a stretching process of stretching the part to be the enlarged diameter part in the direction to be the circumferential direction,
The stretching step is characterized in that , in a cross section that includes the stretching direction and is perpendicular to the steel sheet, only both ends are formed into a corrugated shape ,
The said bending process shape | molds the said extending | stretching part in a predetermined | prescribed expanded pipe shape by the bending process by UO continuous bending, The pipe manufacturing method characterized by the above-mentioned. A pipe manufacturing method for manufacturing a pipe having a large number of punching holes on the pipe surface and an enlarged diameter portion on one end of the pipe,
Molding pitch of the wave shape is synchronized with the punching hole processing pitch, a method of tube manufacture according to claim 1, characterized in that molded with the punching of the wave shape are carried out simultaneously. A mold structure used in the pipe manufacturing method according to claim 1 or 2,
A mold structure characterized in that the bending step is configured to perform bending by UO continuous bending and simultaneously perform tube expansion.