JPH0651209B2 - Hydraulic bulge processing method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a hydraulic bulge processing method, and particularly to a bulging portion, particularly a rounded shape, when bulging a bulging portion of a pipe material. The present invention relates to a hydraulic bulge processing method capable of bulging a straight portion as much as possible without reducing the wall thickness.

[Conventional technology]

Conventionally, a hydraulic bulge processing method is known as one of the methods for processing a pipe into a T shape or the like. More specifically, a pipe material to be processed is loaded between an upper mold and a lower mold, and compression pistons are applied to both ends of the pipe material, and the mold is clamped from the inside of each piston. In addition to making it possible to supply ultra-high pressure liquid into the material, place a swelling allowable piston in the hole provided in the mold at the position corresponding to the swelling planned part of the pipe material, and place the ultra-high pressure liquid in the pipe material. Supply,
This is a method of processing a pipe material into a T-shape or the like by causing a predetermined portion of the bulging process to bulge by a predetermined amount as the bulge-allowing piston retracts.

Conventionally, when the pipe material is bulged, the pressure receiving surface of the bulge-permitting piston 6 abuts only on the planned bulging portion of the pipe material, and the rounded portion directly follows the wall of the lower mold 3. It was something that could be transformed.

[Problems to be solved by the invention]

Therefore, when the pipe material is bulged, the drag force of the piston that retracts to allow bulging in a T-shape acts only on the end surface of the bulging portion of the pipe material. The drag force of the bulge-allowing piston is lower than the internal pressure of the pipe in order to prevent rupture and the like during bulging of the pipe material and swell satisfactorily, but it is set to be considerably large. Therefore, the pressure difference between the internal and external pressures is relatively small at the bulging process area.

However, as described above, such a large drag does not act at a place other than the planned bulge processing part, and as described above, it is only along the wall of the lower mold, and substantially other than the bulge processed part of the pipe material. Since only the atmospheric pressure acts on the surroundings, the differential pressure between the internal and external pressures becomes large (internal pressure> external pressure), and the bulging base, etc., which is deformed into a round shape particularly during the bulging process, is prone to thinning. In some cases, pinholes were sometimes generated. As a result, it has been difficult to lengthen the extended portion of the bulged portion that extends straight along the hole of the mold due to the bulging process.

Therefore, the object of the present invention is that the pressure difference between the inner pressure and the outer pressure becomes uniform at any portion of the pipe material, and even if the bulging process is performed, the bulging portion base portion, etc., which is deformed into a rounded shape, is reduced in thickness. Another object of the present invention is to provide a hydraulic bulging method capable of forming a long bulging extension extending straight along a hole of a mold without causing pinholes or cracks.

[Means for solving problems]

The present invention has been made in view of the above points, and has the following technical means.

That is, according to the present invention, the pipe material 1 to be processed is loaded between the upper mold 2 and the lower mold 3, and both ends 1 ', 1'of the pipe material 1 are loaded.
The pistons 5 and 5 for compression are applied to the pistons 5 and 5 so that the ultra-high pressure liquid P can be supplied from the inside of the pistons 5 and 5 into the pipe material 1 that has been clamped, and the pipe material 1 is bulged. A bulge-permitting piston 6 is placed in a hole 4 provided in the mold at a position corresponding to the planned portion 1a, and the superhigh pressure liquid P is supplied into the pipe material 1 to bulge the bulge-processing planned portion 1a. In the hydraulic bulge processing method of processing the pipe material 1 into a T-shape or the like by swelling a predetermined amount with the retreat of the base material; Pressure receiving surface 6a of the piston 6 and the outer peripheral surface of the pipe material 1
A liquid Q such as oil is interposed between the pipe material 1e and the pipe material 1 and super-high pressure liquid pressure is applied to bulge the bulging-processed portion 1a. In the hydraulic bulging method, the intervening hydraulic pressure can be applied to the bulging portion base portion 1c which is deformed into the round shape of the bulging portion of the pipe material during the backward movement.

[Action]

A liquid Q such as oil is placed between the swelling portion 1a of the pipe material 1 clamped between the upper and lower dies 2 and 3 and the swelling allowable piston 6 capable of swelling into a T-shape. Through. Then, the bulge-permitting piston 6 is applied to the bulge-processing planned portion 1a.

Next, the ultrahigh pressure liquid P is supplied into the pipe material 1 from the compression pistons 5 and 5 at both ends 1 ′ and 1 ′ of the pipe material 1, and the pipe material 1 is axially supported while keeping the liquid pressure P in the pipe 1 tight. Compress in direction. Since the outer peripheral surface 1e of the pipe material 1 is surrounded by the fixed upper and lower molds 2 and 3, the pipe material 1
The swelling-scheduled portion of the swelling-allowed piston 6 applied to the swelling-scheduled portion 1a of the pipe material 1 through the intervening liquid Q is provided while being able to descend in the hole 4 formed in the sole mold. It bulges as if you push down. At this time, the drag force of the backward swelling permissible piston 6 is transmitted through the intervening liquid Q, but the intervening liquid Q is uniformly present between the outer peripheral surface 1e of the pipe material 1 and the upper and lower molds 2, 3. Therefore, it does not particularly act only on the bulging portion end portion 1b, but also uniformly acts on the bulging portion base portion 1c and the like that are deformed into a round shape in accordance with the bulging process. That is, at any position of the pipe blank 1, the pressure difference between the inner and outer pressure (-)
Will be uniform. Therefore, during bulging processing, the bulging portion base
It is difficult for the wall thickness of 1c and the like to occur, and as a result, the bulging portion extending portion 1d that extends straight along the hole 4 of the die can be bulged for a long time for molding.

〔Example〕

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

FIGS. 1 (A) to (H) are views showing a process of bulging and forming a pipe material into a T shape.

In FIG. 1 (A), reference numeral 1 denotes a pipe material such as a metal pipe, which is loaded between an upper mold 2 and a lower mold 3 fixed by a mold clamping press (not shown). A hole 4 is formed in the center of the lower mold 3 as a space for bulging the pipe material 1 into a T-shape, and the bulging processing of the pipe material 1 is performed in the hole 4 at the forward limit position. A bulge-permitting piston 6 is provided which is applied to the planned portion 1a through an intervening liquid described later and allows the bulging of the bulging-processed portion 1a while retreating.

At both ends 1 ', 1'of the pipe material 1, the pipe material 1
The compression pistons 5 and 5 for axially compressing and compressing are compressed. The compression pistons 5 and 5 communicate with the inside of the pipe material 1, and the ultrahigh pressure liquid P is introduced into the pipe material 1. It has injection holes 5a, 5a that can be supplied.

Now, as shown in FIGS. 1 (A) and (B), the pipe material 1 is set between the upper and lower molds 2 and 3, and the compression pistons 5 and 5 are applied to both ends 1'and 1 ', and further, As shown in FIG. 1C, the ultrahigh pressure liquid P is supplied into the pipe material 1 through the injection holes 5a, 5a of the pistons 5, 5. FIG. 1 (D) shows a swelling-permitting piston 6 which is provided in the hole 4 of the lower mold 3 while the liquid P is supplied to the pipe material 1 so that a sufficient fluid pressure for swelling is obtained. As shown, it is moved forward and applied to the bulging-scheduled portion 1a. At this time, conventionally, since the bulge-allowing piston 6 is brought into contact with the bulge-processing target portion 1a, the above-described problem occurs.

Therefore, according to the present invention, as shown in FIGS. 1 (A) to (C), a sufficient amount of oil or the like is required to uniformly intervene in the gap between the outer peripheral surface 1e of the pipe material 1 and the upper and lower molds 2, 3. The high-pressure liquid Q is previously interposed in the hole 4 between the pressure receiving surface 6a of the swelling-permitting piston 6 and the swelling-processed portion 1a.
When the pressure receiving surface 6a is pressed against the swelling processing portion 1a through the intervening liquid Q, the intervening liquid Q is also interposed between the outer peripheral surface 1e of the pipe material 1 and the upper and lower molds 2, 3. I did it.
At this time, the intervening liquid Q is naturally sealed by the upper molds 2 and 3, the compression pistons 5 and 5, and the bulging-permitting piston 6.

The operation will be described below.

As shown in FIG. 1 (D), the pipe material 1 is supplied with an ultrahigh pressure, and as shown in FIG. 1 (E), the pipe material 1 is axially applied by the compression pistons 5 and 5. When compressed, the outer peripheral surface 1e of the pipe material 1 is fixed.
Although it is surrounded by 3, the swelling piston 1 provided only for retraction is pushed down via the intervening liquid Q, and the swelling processing portion 1a is swelled, and the internal pressure P of the pipe material 1 is compressed. The same state as before is maintained. When the compression and compression of the compression pistons 5 and 5 is further advanced, the bulging portion end portion 1b further pushes down the bulging allowable piston 6 via the intervening liquid Q. Conventionally, it was difficult to lengthen the bulging portion extension 1d extending straight along the hole 4 to the position shown in FIG. 1 (F).

That is, if the bulging portion extended portion 1d is elongated to this extent, the bulging portion base portion 1c, which is deformed into a round shape due to the bulging process, is likely to be thinned. If the intervening liquid Q is used as in this embodiment, the reaction force of the swelling-allowing piston 6 is caused not only by the bulging end 1b but also by the intervening liquid Q as shown in FIG. 1 (G). It also acts on the bulging portion base portion 1c and the like, where the wall thinning was likely to occur.
That is, the internal pressure of the pipe material 1 is uniform in each part, but the external pressure is also uniform in each part due to the intervening liquid Q.
Therefore, the pressure difference (-) between the inner pressure and the outer pressure is uniform at any position, and there is little possibility that the wall thickness will be reduced at a specific place such as the base of the bulging portion.

As described above, even if the compression and compression of the compression pistons 5 and 5 is large, the internal pressure of the pipe material 1 is kept constant while the swelling allowable piston 6 is retracted.
−) Is always kept constant until the limit bulging of the pipe material.

Therefore, as shown in FIG. 1 (G), the bulging portion extension 1d can be bulged and formed longer. Arrow W in Fig. 1 (G)
Indicates that the bulging portion base 1c for partially indicating that the intervening liquid Q is interposed between the outer peripheral surface 1e of the pipe blank 1 and the upper and lower molds 2 and 3 is partially enlarged. When the bulging process is completed, the ultrahigh pressure liquid P in the pipe material 1 is extracted and the pipe material 1 is removed from the molds 2 and 3 as shown in FIG. 1 (H).

By interposing the intervening liquid Q between the outer peripheral surface 1e of the pipe material 1 and the upper and lower molds 2, 3, the pipe material 1
Since the frictional resistance when compressed by the compression pistons 5 and 5 is reduced, the pipe material 1 can be compressed smoothly and can be swelled satisfactorily. or,
By reducing the frictional resistance, pinholes and the like that were likely to occur particularly in the bulged portion base portion 1c having a rounded shape are less likely to occur.

〔The invention's effect〕

As can be seen from the above, when the pipe material is bulged into a T-shape or the like, the bulging-processed portion is T-shaped.
A liquid such as oil is interposed between the pressure receiving surface of the swelling-allowing piston and the outer peripheral surface of the pipe material so that the swelling can be performed in a character shape.
While the super-high pressure hydraulic pressure is supplied to the inside of the pipe material to bulge the swelling process part and the swelling piston is retracted through the intervening liquid, the intervening hydraulic pressure is changed to the round shape of the pipe material bulging portion. Since it is possible to apply pressure to the base of the bulging part that can be deformed, it is possible to uniformly reduce the pressure difference between the internal and external pressures at any position of the pipe material. It is possible to reduce the frequency of occurrence of pinholes and cracks without reducing the thickness of the bulging part base that was likely to occur, and as a result, it is possible to straighten along the hole of the mold which was conventionally difficult. Bulging part that extends The bulging process can be easily realized to make the extending part as long as possible.

[Brief description of drawings]

FIGS. 1 (A) to 1 (H) are diagrams of an embodiment, and are views sequentially showing steps of bulging and forming a pipe material into a T shape. In the figure, 1 ... pipe material, 2 ... upper mold, 3 ... lower mold,
4 ... hole, 5 ... compression piston, 5a ... injection hole, 6 ... expandable piston, 6a ... expandable piston pressure receiving surface, P ... super high pressure liquid supplied into pipe, ...... The hydraulic pressure in the pipe (internal pressure), Q ... intervening liquid, ... intervening hydraulic pressure (external pressure).

Claims (1)

[Claims] 1. A pipe material 1 to be processed is loaded between an upper mold 2 and a lower mold 3, and compression pistons 5 and 5 are applied to both ends 1'and 1'of the pipe material 1, respectively. It is possible to supply the ultrahigh pressure liquid P from the inside of each piston 5, 5 into the pipe material 1 that has been clamped, and the holes provided in the mold at positions corresponding to the swelling processing portion 1a of the pipe material 1. 4, the swellable piston 6 is arranged, the ultrahigh pressure liquid P is supplied into the pipe material 1, and the swelling processing scheduled portion 1a is swelled by a predetermined amount as the swellable piston 6 is retracted, so that the pipe material 1 is In a hydraulic bulging method for processing into a T shape, etc .; the pressure receiving surface 6a of the swelling allowable piston 6 and the pipe material 1 for allowing the swelling scheduled portion 1a to swell into a T shape or the like. Outer peripheral surface
A liquid Q such as oil is interposed between the pipe material 1e and the pipe material 1 and super-high pressure liquid pressure is applied to bulge the bulging-processed portion 1a. A hydraulic bulging method characterized in that the intervening hydraulic pressure can be applied to the bulging portion base portion 1c which is deformed into the rounded shape of the bulging portion of the pipe material during the backward movement.