JPH06134526A - Method and device for bending piping of stainless steel - Google Patents

Abstract

PURPOSE:To provide a stainless steel piping bending method and device which can bend the piping in a small radius of curvature while preventing the generation of cracks causing particle. CONSTITUTION:A bending part of a piping is bent while heating to 100-400 deg.C. A bending device is provided with an inner die 13 having a heater 17 and an outer die 14, and a piping is bent by engaging the piping P to be bent to an engaging part 16, setting between the inner die 13 and the outer die 14, and turning the outer die 14 along the outer circumference of the inner die 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for bending stainless steel piping, and more specifically, to particles generated during bending such as stainless steel (SUS) piping used in a semiconductor thin film manufacturing apparatus. The present invention relates to a method and a device for bending pipes used for those that affect device performance, particularly with a small radius of curvature.

[0002]

2. Description of the Related Art Generally, when a pipe is bent, a crack is generated on the inner surface of the pipe.
Particles generated due to cracks in the bent portion of the S pipe may be entrained by the fluid flowing in the pipe and enter the growth chamber where the thin film is formed, and adversely affect the quality of the thin film to be manufactured. It was Particles caused by such bending of the SUS pipe can be reduced by performing the purge for a sufficient time after the bending, but for that purpose, a considerable amount of purge gas and time are required. Have to spend.

It should be noted that the use of a tube whose inner surface is electropolished (EP tube) can reduce particles during bending as compared with the case of using a normal bright annealing tube (BA tube), but it cannot be ignored. In addition to the generation of particles, the EP tube is more expensive than the BA tube, so the EP tube has the disadvantage of increasing the cost.

If the radius of curvature of the bent portion is increased, the amount of particles generated is reduced. For example, the radius of curvature is 1 times the diameter of the pipe as compared with the case where the radius of curvature is 3 times the diameter of the pipe.
It is known that the particle generation amount becomes about 1/10 when it is multiplied by 0, and SU is generated without generating particles.
As one means for bending the S pipe, the radius of curvature of the bent portion is set to about 10 times the pipe diameter.

However, if the radius of curvature of the bent portion of the pipe is increased, the length of the bent portion of the pipe becomes significantly longer than that of the normally used one having a radius of curvature of three times. However, a large piping space is required, and there is an inconvenience of increasing the size of the entire apparatus.

On the other hand, if a bent member (elbow) is used in the bent portion, the bent portion of the pipe can be formed with a small radius of curvature and almost no particles are generated, but it is formed separately in this way. When an elbow is used, it takes time and cost to prepare a large number of elbows and weld both ends of the elbow, resulting in an increase in cost of the device.

Therefore, an object of the present invention is to provide a method and apparatus for bending a SUS pipe which can bend a pipe with a small radius of curvature while preventing the generation of cracks that cause particles.

[0008]

In order to achieve the above object, the method for bending a pipe of the present invention is characterized in that the bending portion of the pipe is bent while heating at 100 to 400 ° C. The pipe bending apparatus of the present invention is an inner die having an outer diameter corresponding to the inner diameter of the bent portion of the pipe, and an inner die having a distance corresponding to the pipe diameter between the inner die and the inner die. An outer die that rotates along the outer periphery of the die and an engaging portion that engages the pipe on the bending start side are provided, and the pipe to be bent is 100 to 400 ° C. in the inner die and the outer die.
The feature is that a heater for heating is installed.

[0009]

[Operation] By applying heat to the bent portion of the pipe, plastic working is performed smoothly, the amount of cracks on the inner surface of the pipe decreases, and the amount of particles generated from the cracks decreases. At this time, the heating temperature of the SUS pipe is 100 ° C., which is the lowest temperature at which stainless steel can be smoothly plastic-worked, and the surface is oxidized when heated to 400 ° C. or higher.

[0010]

The present invention will be described in more detail below with reference to the drawings. 1 to 3 show 1/4 SUSBA
The cracks C on the inner surface of the pipe are shown when the pipes are bent at 230 ° C., 140 ° C., and room temperature with a radius of curvature three times the diameter (R = 3D). It can be seen that the amount of cracks on the inner surface when heated and bent is much smaller than the amount of cracks on the inner surface when bent at room temperature shown in FIG.

FIG. 4 shows a measurement of the number of particles generated when the above pipe is similarly bent. When the pipe is bent at room temperature, a large amount of particles are generated during bending, and after bending, It can be seen that a large number of particles are generated even when shocked.

FIG. 5 shows the particle size distribution of the generated particles. In the case of bending at room temperature, particles of each particle size are uniformly generated, and it is clear that it is a particle component in the atmosphere. Is different. On the other hand, 230
In the case of bending at 140 ° C. and 140 ° C., particles of each particle size are uniformly generated, but it is understood that the generation amount is significantly reduced. Although FIG. 5 shows the experimental results for the BA tube, a significant particle reduction effect was also observed for the EP tube.

FIG. 6 shows an embodiment of an apparatus for performing bending while heating the bending portion of the SUS pipe as described above. Particularly, the SUS pipe having a small diameter which is often used in a semiconductor thin film manufacturing apparatus. It is suitable for bending.

The bending apparatus 10 includes two handles 11,
An inner mold 13 located inside the bent portion of the pipe and an outer mold 14 located outside thereof are provided at the tip of the pipe 12. The inner mold 13 provided on one handle 11 has an outer periphery thereof. The surface is formed in an arc shape having an outer diameter corresponding to the inner diameter of the bent portion of the pipe P, and the outer die 14 provided on the other handle 12 is rotatably provided at the center of the inner die 13. The inner mold 13 is formed so as to rotate around the inner mold 13 with a distance corresponding to the diameter of the pipe P maintained therebetween via the lever 15. In addition, the pipe P is attached to the tip of one handle 11.
A locking portion 16 that locks a straight portion of the pipe P when bending is performed.

The molds 13 and 14 are provided with a heater 17 for heating the pipe to be bent to 100 to 400.degree. The heater 17 is
It is connected to the power supply unit via a wire (not shown). Further, it is preferable to adopt a heat insulating structure for reducing the heat loss of the heater 17 for both molds 13 and 14 or both handles 11 and 12.

In order to bend the SUS pipe P by using the bending apparatus 10, first, the pipe P that has been preheated as necessary is placed in the inner mold 13 with both the handles 11 and 12 open. It is inserted between the outer mold 14 and the outer mold 14, and the pipe P on the bending start side is locked to the locking portion 16 at the tip of the handle 11. Then, after confirming the heating state of the pipe P by the heater 17, when the handles 11 and 12 are closed as shown by imaginary lines in the figure, the outer mold 14 relatively rotates along the periphery of the inner mold 13. The pipe P that is moved and sandwiched between the two molds 13 and 14 is bent into a radius of curvature substantially corresponding to the outer diameter of the inner mold 13.

As described above, by using the apparatus shown in this embodiment, it is possible to easily perform the bending work while heating the pipe P, and as described above, the bending work in which almost no particles are generated is extremely easy. Can be done.

The method of the present invention can be carried out without using the above bending apparatus.
The pipe heated to a predetermined temperature may be set in a commonly used pipe bending machine, and the bending may be performed while the temperature does not drop.

[0019]

As described above, according to the present invention,
It is possible to perform bending with a small radius of curvature while suppressing the generation of particles with a simple operation, and it is possible to inexpensively provide SUS piping for a complicated device such as a semiconductor thin film forming device.

[Brief description of drawings]

[Figure 1] SU that was bent while heating to 230 ° C
It is a figure which shows the state of the inner surface of S piping.

[Fig. 2] SU subjected to bending while heating to 140 ° C
It is a figure which shows the state of the inner surface of S piping.

FIG. 3 is a diagram showing a state of an inner surface of a SUS pipe bent at room temperature.

FIG. 4 is a diagram showing the number of particles generated when bending is performed at each temperature.

FIG. 5 is a diagram showing a particle size distribution of generated particles.

FIG. 6 is a front view showing an embodiment of the bending apparatus of the present invention.

[Explanation of symbols]

10 ... Bending device, 13 ... Inner mold, 14 ... Outer mold, 16 ...
Locking part, 17 ... Heater

Claims (2)

[Claims] 1. A method for bending a stainless steel pipe, which comprises bending the stainless steel pipe while heating the bent portion of the pipe to 100 to 400 ° C. 2. An apparatus for bending a stainless steel pipe, wherein an inner die having an outer diameter corresponding to an inner diameter of a bent portion of the pipe and a distance corresponding to the pipe diameter are provided between the inner die and the inner die. An outer mold that keeps and rotates along the outer periphery of the inner mold, and a locking portion that locks the pipe on the bending start side,
The inner mold and the outer mold are 100 to 40 pipes to be bent.
A bending device for stainless steel piping, which is equipped with a heater for heating to 0 ° C.