JPH0635862B2 - Method for manufacturing high-pressure fuel pipe for diesel engine - Google Patents

Description

The present invention relates to a method for manufacturing a fuel high pressure pipe for a diesel engine.

<Prior Art> A high-pressure fuel pipe for a diesel engine is generally formed by cold drawing an STS material. In this cold drawing, wrinkles and scratches that cannot be avoided in the process occur on the inner surface of the pipe. In addition, the fuel supply pressure has increased due to recent countermeasures against low-quality oil, and the STS material used for the high-pressure pipe has been changed to a thick-walled pipe of SCM material to cope with this problem. Since it is formed by processing, as shown in Reference Photo 1, scratches and wrinkles occur on the inner surface of the pipe, and the maximum scratch depth is 0.15 mm. If there are such scratches or wrinkles, an accident such as a rupture of the high-pressure fuel pipe will occur, resulting in a ship fire or the like. Therefore, in order to remove the scratches and wrinkles from the inner surface of the tube, the inner surface boring is performed after the cold drawing and the cold drawing is repeated several times, and then the ultrasonic tube is drawn. After such treatment, as shown in Reference Photo 2, the depth of scratches on the inner surface of the pipe is 0.01-
It is 0.035 mm, and the flaw is not completely removed yet. If any scratches remain on the inner surface of the pipe, cracks will occur from the scratches, so cold-drawn pipes cannot be used with scratches. Processing has been adopted for gun drills to produce flawless high-pressure pipes.

<Problems to be Solved by the Invention> However, there are the following problems in the processing of the fuel high-pressure pipe by the gun drill and the fuel high-pressure pipe obtained thereby.
Since gun drilling is a drilling process, the length of the pipe to be processed is naturally limited, and when using the above pipe for long pipes, it is necessary to divide it into several parts and the number of parts increases,
There is a problem that increases the cost. Furthermore, since gun drilling is forcibly cut by a drill, there is a problem in that a tube with uneven thickness is generated. Furthermore, there is a problem that chips generated during machining remain inside the pipe and cause an engine stop during test operation. While it is necessary to provide dedicated equipment for gun drill processing, there is a problem in that providing the above equipment rather increases the cost because defective products frequently occur in the processed pipe. Therefore, an object of the present invention is to produce a diesel engine fuel high pressure pipe capable of easily and completely removing wrinkles and scratches on the inner surface of a long thick steel pipe formed by cold drawing to prevent the occurrence of cracks. Is to provide a method.

<Means for Solving Problems> In order to achieve the above object, the method for producing a fuel high pressure pipe for a diesel engine according to the present invention comprises: forming a long thick steel pipe by cold drawing; Blowing in the blast through a tapered nozzle whose inner diameter is tapered from the opening at one end of
While grinding the inner surface of the thick-walled steel pipe to a certain size, blowing the blast through the tapered nozzle from the other end opening of the thick-walled steel pipe, after grinding the inner surface of the thick-walled steel pipe to a certain size, the thick wall It is characterized in that a head portion with a connecting flange is formed at both end openings of the steel pipe, and then the inner surface of the thick steel pipe is reamed.

<Example> Hereinafter, the present invention will be described in detail with reference to illustrated examples.

FIG. 1 is a sectional view of a long thick steel pipe 1 formed by cold drawing, and the material of the thick steel pipe 1 is, for example, SC.
M material has an outer diameter of 12.0 to 15.0 mm, an inner diameter of 2.8 to 4.8 mm, and a length
It is 1500 mm long. The long length is defined as steel pipe length / steel pipe outer diameter (1 / D) = 100 or more. As shown in Reference Photo 1, the scratch depth on the inner surface of the steel pipe in this state is 0.15 mm.
Has become.

First, as shown in FIG. 2 and FIG. 3, a blast pressure of 5 is obtained by blasting the abrasive from only the opening on the A end side of the steel pipe 1.
A case where the scratches on the inner surface of the steel pipe 1 are removed by continuously grinding at kg / cm ² for 3 minutes will be described. In this case, the grinding amount of the inner surface of the steel pipe is 0.015 mm at the A end, 0.05 mm at the center, and 0.15 m at the B end.
It is m. Furthermore, if the duration of shot blasting is increased to 4 minutes and 5 minutes, the grinding amount of the inner surface of the steel pipe is 0.02 mm to 0.04 mm, 0.06 mm to 0 at the A end, the central part and the B end, respectively.
075 mm, 0.21 mm to 0.23 mm, and the amount of grinding on the outlet side of the abrasive grains, that is, the B end is extremely large compared to the A end, and deviates to the B end.

Therefore, in the present invention, as shown in FIG. 4 and FIG. 5, the blast pressure is 5 Kg / cm ² from the openings on both end sides of the steel pipe 1 at the both ends, and the inner surface of the steel pipe is shot blasted continuously for 4 minutes. Grind with. The grinding amount of the inner surface of the steel pipe is 0 at the A end.
18 mm, 0.1 mm at the center and 0.19 mm at the B end. Furthermore, if the blast pressure is increased to 6 kg / cm ² and the duration of shot blasting is extended to 6 minutes, the grinding amount on the inner surface of the steel pipe increases, 0.4 to 0.48 mm at the A end, 0.18 to 0.19 mm at the central part,
The B end has a size of 0.36 to 0.37 mm, the grinding amount at the A end is almost the same as that at the B end, and as shown in Reference Photo 3, flaws and wrinkles on the inner surface of the steel pipe are completely removed. Furthermore, FIG.
As shown in (a) and (c), at this time, the average roughness of the inner surface of the steel pipe was 6 μ at the A end, 4.75 μ at the center, and 2.75 μ at the B end, which was very small, about 3S. There is.

In this way, by blowing blast from both ends of the steel pipe 1, the inner diameter of the steel pipe expands from the center to both ends as shown in FIGS. It has approximately the same diameter and exhibits a smooth and uniform hardness.

Since the inner surface of the thick steel pipe 1 is ground by blasting,
The abrasive grain polishing apparatus shown in the figure is used. In this apparatus, a thick steel pipe 1 is sandwiched between a vacuum hose 2 and one end of a blast hose 3, and one end of the vacuum hose 2 is connected to an upper part of a recovery tank 4. The other end of the blast hose 3 is connected to the bottom of the pressure tank 5, and one end of the air supply pipe 6 is connected to the bottom of the pressure tank 5. A branch 7 is provided in the middle of the air supply pipe 6 and is connected to the upper portion of the processing tank 5. The top surface of the pressure tank 5 and the bottom surface of the recovery tank 4 are connected via a valve 8. The upper part of the recovery tank 4 and the dust collector 9 are connected by a connecting pipe 10, and a blower 11 is installed on the dust collector 9.

Then, high-pressure air is introduced from the air supply pipe 6 to the processing tank 5 through the branch pipe 7 to pressurize the shot blast 23 in the processing tank 5, and by the air sent from the air supply pipe 6 toward the blast hose 3 by pressure. Shot blast is blown into the blast hose 23 from the bottom of the processing tank 5, the blast is injected into the thick-walled steel pipe 1 together with high-pressure air, the inner surface is ground, and then this blast is conveyed from the recovery hose 2 to the recovery tank 4. And collect. Since the connecting portion between the abrasive grain grinding device and the thick-walled steel pipe 1 to be ground has a simple structure including only the tapered nozzle 22 and the blast hose 3, it is easy to handle and can be blasted easily.

Thick-walled steel pipe 1 ground by a predetermined amount using the above device
The openings at both ends of the upset are as shown in Fig. 11.
1a and 1b are formed by forging using a die. Due to this hot forging, the inside of the fuel high-pressure pipe 1 where both ends are expanded bulges inward. The outer periphery of the upset portions 1a and 1b is first
Turning as shown in Fig. 2 and the upset part
The protrusions 1c and 1d formed on the inner surfaces of 1a and 1b are removed by edge reaming as shown in FIG. In this case, since the inner surface of the steel pipe 1 has substantially the same diameter by the above forging, the reaming amount is small, and the inner surface as it is after blasting remains substantially, and smooth and substantially uniform hardness is obtained.

Next, a thick-walled steel pipe automatic polishing apparatus for sequentially and continuously grinding the inner surfaces of a plurality of thick-walled steel pipes 1 will be described with reference to FIGS. 8 to 10. In this device, an automatic indexing device 13 is fixed to a mount 12. One end of the rotary shaft 14 is connected to the shaft end of the automatic indexing device 13, and both ends of the rotary shaft 14 are supported by bearings 31 and 32. The rotating shaft 1
4 has two disc-shaped mounting plates 15 and 16,
One of the mounting plates 15 is attached to one end of the rotary shaft 14 by the mounting plate 1 described above.
The center of 5 is fixed, and the other mounting plate 16 is slidably mounted along the key groove 17 from the other end of the rotary shaft 14 to the central part. V is evenly spaced on the outer circumference of the mounting plates 15 and 16.
V-shaped grooves 18, 18, 18, ... Are engraved. The thick steel pipes 1, 1, 1, ... Are fitted in the grooves 18, 18, 18 ,.
Further, the piston 20 is fixed to the mounting base 12, the tip of the blast hose 3 is fixed to the piston rod 21 of the piston 20, and the tapered nozzle 22 having a tapered inner diameter is attached to the tip of the blast hose 3. ing. The center line of the tapered nozzle 22 and the center lines of the steel pipes 1, 1, 1, ... Attached to the mounting plates 15 and 16 are made to coincide with each other as the mounting plates 15 and 16 rotate at a constant angle. There is.

In order to form a fuel high pressure pipe for a diesel engine using the above-described thick-walled steel pipe automatic polishing apparatus, first, as shown in FIG. 1, the thick-walled steel pipe 1 is formed by cold drawing. Next, as shown in FIG. 8, the thick steel pipe 1 is fixed to the grooves 18 of the mounting plates 15 and 16 by the clamps 19. Then, the automatic indexing device 13
Is operated to rotate the mounting plates 15 and 16 by a predetermined amount. Then, the piston 20 is operated to bring the tapered nozzle 22 into contact with one end surface of the thick-walled steel pipe 1. As shown in FIG. 14, the blast 23 is blown into the thick steel pipe 1 together with the pressurized air from the tapered nozzle 22. At this time, since the packing 24 is interposed between the tapered nozzle 22 and the one end opening of the thick steel pipe 1,
The blast 23 is blown into the thick-walled steel pipe 1 without leaking to the outside. Blasting of the blast 23 is performed for 3 minutes continuously at a blast pressure of 6 kg / cm ² , and the inner surface of the thick-walled steel pipe 1 is ground. Next, the inner surface of the thick-walled steel pipe 1 is ground from the opening of the other end of the thick-walled steel pipe 1 for 3 minutes continuously at a blast pressure of 6 kg / cm ² as described above. As a result, the inner surface of the thick-walled steel pipe 1 has a diameter of 0.
2-0.3 mm is ground. Reference Photo 1, Figures 5 and 6
As shown in (a) to (c), the thick-walled steel pipe 1 is sprayed and its inner surface is ground to remove scratches and wrinkles on the inner surface. Further, the thick steel pipe 1 is turned over and attached to the mounting plates 15 and 16 in reverse, and the tapered nozzle 22 is brought into contact with the other end surface and is ground by shot blasting from the other end surface to completely remove scratches and wrinkles on the inner surface. To remove. In this way, when grinding is performed from both ends of the thick-walled steel pipe, there is little difference between the most ground part and the least ground part as shown in FIG. In addition, when an unwidened nozzle is used for blasting or when blasting is performed from only one end of the steel pipe, it is impossible to obtain a substantially uniform pipe inner diameter and a smooth and substantially uniform inner surface over the entire length as described above.

Therefore, since the thick-walled steel pipe 1 ground from both ends in this way is ground uniformly without uneven thickness and wrinkles and flaws are completely removed, cracks may occur during use of the fuel high-pressure pipe as a product. It disappears. Then, FIG.
As shown in FIG. 12, hot upset portions 1a and 1b are formed in the openings of both ends of the thick-walled steel pipe 1, and the bulged portion is subjected to turning and edge reaming processing, and a head 1e with a flange for connection is formed. , 1f does not make the inside thickness thin, and a high-pressure fuel pipe is conveniently formed. That is, it is not necessary to purposely provide the flanges at the openings at both ends. Since the high-pressure pipe is formed in this way, integrated production is possible.

<Effects of the Invention> In the present invention, even if there are wrinkles or scratches on the inner surface of a long thick-walled steel pipe, the inner surface of the long thick steel pipe is ground by abrasive blasting to completely remove the wrinkles and scratches. Even if a steel pipe is used as a high-pressure fuel pipe, no crack will occur. As a result, it is possible to abolish the step of ultrasonically expanding the tube which has been conventionally performed. Further, since the head portion with the connecting flange is integrally formed in the opening portions at both ends of the thick steel pipe, the number of parts can be reduced and the economical efficiency can be improved.

Further, since the blast of the abrasive is alternately blown from the openings on both ends of the thick-walled steel pipe to grind the inner surface thereof, long thick-walled steel pipes or curved pipes can be ground, and there is a restriction on the length of the fuel high-pressure pipe. At the same time, the amount of grinding in the entire lengthwise direction of the thick-walled steel pipe becomes almost equal, the thickness of the thick-walled steel pipe can be made substantially uniform, and the quality can be stabilized.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a thick-walled steel pipe cold-drawn, and FIG. 2 is a diagram showing an inner surface shape of the thick-walled steel pipe when a blast is blown from an opening on one end side of the thick-walled steel pipe for grinding. Fig. 3 is a cross-sectional view of a thick-walled steel pipe ground by blowing blast from one end opening, and Fig. 4 is a diagram showing the inner surface shape of the thick-walled steel pipe when ground from both end openings of the thick-walled steel pipe, Fig. 5 Is a cross-sectional view of the thick-walled steel pipe in the state of FIG. 4, FIGS. 6 (a), 6 (b), and 6 (c) are diagrams showing the inner surface roughness of the fuel high-pressure pipe, FIG. Is a schematic system diagram of an abrasive grain polishing device that grinds the inner surface of a thick-walled steel pipe by blasting an abrasive, FIG. 8 is a front view of an automatic thick-walled steel pipe feeder, and FIG. 9 is a line II-II in FIG. Fig. 10, Fig. 10 is a sectional view taken along the line III-III in Fig. 8, Fig. 11 is a sectional view showing a state in which the upsets are formed at both ends of the thick-walled steel pipe, and Fig. 12 shows the upset portions at both ends of the thick-walled steel pipe. FIG. 13 is a cross-sectional view showing a state of being machined, FIG. 13 is a cross-sectional view of a thick-walled steel pipe that has undergone turning and small-scale reaming, and FIG. 14 is a cross-sectional view of a state in which blast of abrasive is blown into the thick-walled steel pipe . 1 …… Thick walled steel pipe, 1e, 1f …… Head with flange for connection, 23 …… Blast.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Motomasa Atsui 1-80, Oyodochu, Oyodo-ku, Osaka-shi, Osaka Daihatsu Daisel Co., Ltd. (56) ) Actual development Sho 54-132895 (JP, U) Japanese Patent Sho 49-40773 (JP, B1)

Claims (1)

[Claims] 1. A long thick steel pipe is formed by cold drawing,
The blast of the abrasive is blown through a tapered nozzle whose inner diameter is narrower than one end opening of the thick-walled steel pipe to grind the inner surface of the thick-walled steel pipe to a certain size, and the other end opening of the thick-walled steel pipe Blowing the blast through a tapered nozzle from the portion, after grinding the inner surface of the thick-walled steel pipe to a certain size, to form a head with a flange for connection at both end openings of the thick-walled steel pipe, then the thick-walled steel pipe A method for manufacturing a fuel high-pressure pipe for a diesel engine, which comprises reaming the inner surface of the.