JP2007255677A - Piping flange joint - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piping flange joint for well preventing the corrosion of both a piping member and a flange member while avoiding the crack of the flange member when enlarging the diameter of the piping member in a fitting hole of the flange member and assembling it on the flange member. <P>SOLUTION: The piping flange joint 10 comprises the plate-shaped flange member 12 having the fitting hole 19 passing therethrough in the direction of the plate thickness, and the metal piping member (an aluminum pipe) 14 fitted and assembled in the fitting hole 19 in the condition that the front end is protruded from the plate face of the flange member 12. The flange member 12 is formed of a resin 32 as an insulating material. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a pipe flange joint suitable for use in a refrigerant pipe joint of a refrigeration cycle for air conditioning of a vehicle.

Conventionally, for example, as a refrigerant pipe joint of a refrigeration cycle for air conditioning of a vehicle, a fitting hole penetrating in a plate thickness direction is formed in a plate-like flange member, and a metal pipe member is inserted into the fitting hole at a tip portion. A pipe flange joint is used that is assembled in a fitted state in a state in which it protrudes from the plate surface of the flange member.
In this pipe flange joint, the flange member is fixed to the mating member by a fixing tool such as a bolt, and the tip end portion of the pipe member protruding from the flange member is inserted into the insertion hole of the mating member and connected.

FIG. 2 shows a specific example of this type of pipe flange joint.
In the figure, reference numeral 200 denotes a mating member to which the piping member 208 is connected, and is provided with an insertion hole 202 for inserting the piping member 208.
A pipe flange joint 204 is configured by assembling a pipe member 208 to a plate-like flange member 206.
The flange member 206 is formed with a fitting hole 210 penetrating in the plate thickness direction, and the piping member 208 projects a distal end portion, specifically, a boss portion 211 from the plate surface of the flange member 206 into the fitting hole 210. It is assembled in a fitted state.
An annular groove 212 is formed in the boss portion 211, and an O-ring 214 as a seal member is held therein.

  In this piping flange joint 204, the boss portion 211 of the piping member 208 is inserted into the insertion hole 202 of the mating member 200, and the flange member 206 is applied to the mating member 200, and in this state, is inserted into the fixing hole 216 of the flange member 206. The pipe member 208 is fixed to the mating member 200 in a connected state by screwing the bolt 218 into the female screw hole 220 of the mating member 200.

Conventionally, in this type of pipe flange joint 204, a pipe member 208 is generally made of an aluminum alloy, specifically, a pipe material having a thickness of 1.5 to 2.0 mm such as A6063 or A3003.
As the flange member 206, an aluminum alloy extruded material or a die-cast material is generally used.

  By the way, in the pipe flange joint 204 constructed by assembling metals in contact with each other in this way, if there is a potential difference between the pipe member 208 and the flange member 206, there is a difference between the standard electrode potentials of the two in detail. And a low potential (high ionization tendency) electrically base metal in a corrosive environment and a high potential (low ionization tendency) electrically precious metal form a local battery (galvanic cell) The galvanic corrosion (dissimilar metal contact corrosion) caused by this occurs mainly at the portion indicated by A in FIG.

  In this case, when the pipe member 208 side is an electrically base metal (potential is low), the pipe member 208 is preferentially corroded, and the pipe member 208 has a thickness of 1.5 as described above. Since the thickness is about 2.0 mm, there is a concern that a hole may be formed in the piping member 208 in some cases.

On the contrary, when the flange member 206 side is an electrically base metal, preferential corrosion of the flange member 206 occurs.
When the corrosion proceeds to the inner surface of the fitting hole 210, the close contact between the inner surface of the fitting hole 210 of the flange member 206 and the outer peripheral surface of the piping member 208 is impaired, and the piping member 208 generates rattling in the fitting hole 210. As a result, the fixing strength between the piping member 208 and the flange member 206 is reduced.
Further, when the pipe member 208 is rattled, the sealing performance at the boss portion 211 is adversely affected, and there is a problem that the sealing performance at the same portion is lowered.

As a countermeasure, it is conceivable that the piping member 208 and the flange member 206 are made of the same material so that a potential difference does not occur between the piping member 208 and the flange member 206.
However, even if it is the same material, it is unavoidable that a difference in potential occurs between the two due to variations in material lots, etc. Therefore, if such a difference in potential occurs, corrosion proceeds little by little, and In the long term, it is difficult to avoid the problem that the corrosion becomes large.

In addition, a minute gap is easily generated between the inner peripheral surface of the fitting hole 210 of the hard metal flange member 206 and the outer peripheral surface of the piping member 208. In this case, the fitting portions (FIG. 2 ( B) The crevice corrosion occurs in the portion indicated by B in FIG.
Further, the pipe member 208 is expanded from the inside while being inserted into the fitting hole 210 of the flange member 206, and is forcedly fitted into the fitting hole 210 of the flange member 206. Further, since the flange member 206 is made of a hard metal, there is a problem that the flange member 206 is cracked in some cases.

The present invention has been devised to solve such problems.
In Patent Document 1 below, a sacrificial corrosion layer made of a material that is electrically lower than the pipe member is formed on the outer peripheral surface of the metal flange member for the purpose of solving the corrosion problem in the pipe flange joint. The point is disclosed.
Patent Document 2 below discloses that the flange member is made of an aluminum alloy containing zinc that is electrically base with respect to the piping member, and the potential of the flange member is reduced with respect to the piping member. Yes.

  However, the one disclosed in Patent Document 1 cannot solve the problem of corrosion in the fitting hole, the improvement of adhesion, and the problem of cracking of the flange member when the pipe member is expanded. Since the corrosion of the flange member itself greatly occurs, it is not possible to sufficiently solve the problem of rattling of the piping member in the fitting hole and the deterioration of the sealing performance due to this.

Japanese Patent Laid-Open No. 9-178061 Japanese Patent No. 3003765

  The present invention is based on the above circumstances and can satisfactorily prevent corrosion of both the piping member and the flange member. Further, the piping member is expanded in the fitting hole of the flange member, and this is flanged. The purpose of the present invention is to provide a pipe flange joint that does not cause cracks in the flange member even when assembled to the member.

  Thus, according to the first aspect of the present invention, a fitting hole penetrating in the plate thickness direction is formed in a plate-like flange member, a metal pipe member is formed in the fitting hole, and a distal end portion of the flange member is formed. In the pipe flange joint assembled in a fitted state so as to protrude from the plate surface, the flange member is made of resin as an insulating material.

  According to a second aspect of the present invention, in the first aspect, the surface of the flange member excluding the inner surface of the fitting hole is coated with a sacrificial corrosion layer made of a metal that is electrically lower than the piping member. It is characterized by.

Effects and effects of the invention

As described above, according to the present invention, the flange member in the pipe flange joint is made of resin which is an insulating material.
According to this invention, in addition to being able to reliably prevent galvanic corrosion due to contact between different metals, in addition to expanding the pipe member made of metal in the fitting hole and assembling the flange member, the resin Since the deformability of the flange member made of is larger than that of the metal flange member, it is possible to satisfactorily prevent the flange member from cracking when the pipe member is expanded, and based on the high deformability In addition, the adhesion of the outer peripheral surface of the piping member to the inner peripheral surface of the fitting hole can be increased, the fixing strength between the piping member and the flange member can be increased, and the outer peripheral surface of the piping member and the inner peripheral surface of the fitting hole can be increased. It is possible to satisfactorily suppress or prevent crevice corrosion caused by a gap between them.

Here, the resin material preferably has a required material strength in order to prevent loosening of the tightening force by bolts or from the viewpoint of preventing deformation of the flange member at the time of tightening and fixing. A rate of 0.8 GPa or more is desirable.
In order to further increase the strength, a resin material to which a reinforcing material such as a chemical fiber is added can be used as necessary.

According to a second aspect of the present invention, the surface of the flange member excluding the inner surface of the fitting hole is coated with a sacrificial corrosion layer made of a metal that is electrically lower than the piping member.
This sacrificial corrosion layer exhibits the effect of preventing corrosion of metal piping members by preferentially and actively corroding itself in a corrosive environment. According to claim 2, the flange member is made of resin. Compared with the case where only the material is used, the crevice corrosion of the piping member at the fitting portion between the piping member and the fitting hole can be more effectively suppressed or prevented.

As a method of coating the sacrificial corrosion layer, metal fine particles that form the sacrificial corrosion layer are sprayed onto the resin surface at a high speed, and this is squeezed into the surface for coating (high-speed shot peening treatment). Can be suitably used, but various other coating techniques can also be used.
For example, a coating method using dry plating or wet plating can be used. Alternatively, a metal for forming the sacrificial corrosion layer is formed into a thin plate in advance, and this is bonded to the resin surface with an adhesive or the like. It is also possible to form a sacrificial corrosion layer.

Here, the sacrificial corrosion layer is preferably coated with a film thickness of 0.01 mm to 0.50 mm.
If the film thickness is less than 0.01 mm, the life of the sacrificial corrosion effect due to sacrificial corrosion in the sacrificial corrosion layer is short. Due to the deformation, the sacrificial corrosion layer is cracked and easily dropped. Thus, if the sacrificial corrosion layer falls off, the anticorrosion effect due to sacrificial corrosion may be lost.

  In the present invention, magnesium can be particularly preferably used as the electrically base metal for forming the sacrificial corrosion layer.

Next, embodiments of the present invention will be described in detail with reference to the drawings.
In FIG. 1, reference numeral 10 denotes a pipe flange joint of the present embodiment, which is constructed by assembling an aluminum pipe 14 made of an aluminum alloy as a pipe member to a plate-like flange member 12.
The flange member 12 is provided with a fixing hole 16 penetrating in the plate thickness direction. The flange member 12 is fixed to the mating member 18 by inserting a bolt into the fixing hole 16 and screwing it into the female screw hole of the mating member 18.

The flange member 12 is formed with a fitting hole 19 penetrating in the thickness direction at a position different from the fixing hole 16, and the aluminum pipe 14 is assembled in a fitted state there.
Here, the aluminum pipe 14 is expanded at the fitting hole 19, and the outer peripheral surface is pressed against the inner peripheral surface of the fitting hole 19.

The aluminum pipe 14 is assembled to the flange member 12 with the tip portion protruding from the plate surface of the flange member 12, and the tip portion is configured as a boss portion 20.
An annular groove 22 is formed in the boss portion 20, and an O-ring 24 as a seal member is held therein.
That is, the boss portion 20 is inserted into the insertion hole 26 of the mating member 18 and is hermetically sealed with respect to the insertion hole 26 by the O-ring 24.

In FIG. 1, 28 is a large-diameter and annular flange-shaped portion formed in the aluminum pipe 14, 30 is an annular recess formed in the flange member 12, and the flange-shaped portion 28 is in the annular recess 30. It is paid.
The hook-shaped portion 28 and the annular recess 30 are for preventing the aluminum pipe 14 from coming off.

In the present embodiment, the flange member 12 is made of a resin 32 made of an insulating material.
Here, as the resin 32, a resin having a volume resistivity of 1 × 10 ⁵ (Ωm) or more, preferably 1 × 10 ⁷ (Ωm) or more is used.

In some cases, the entire surface except the inner peripheral surface of the fitting hole 19 is coated with a sacrificial corrosion layer 34 made of an electrically base metal having a lower potential than the aluminum pipe 14 (in FIG. 1, the fixing hole 16 is fixed). The inner surface is also removed).
The inner peripheral surface of the fixed hole 16 may be coated with a sacrificial corrosion layer 34 in some cases.

Here, the sacrificial corrosion layer 34 is formed with a film thickness within a range of 0.01 mm to 0.50 mm.
As shown in FIG. 1, the sacrificial corrosion layer 34 is coated on the surface of the resin 32 up to a position in contact with the aluminum pipe 14.

  In the present embodiment as described above, when the flange member 12 is made of a single resin, galvanic corrosion due to contact between different metals can be reliably prevented, and the aluminum pipe 14 is fitted to the fitting hole 19. In the case where the pipe is expanded and assembled to the flange member 12, the flange member 12 made of resin has a large deformability, so that the flange member 12 can be well prevented from cracking and has a high deformability. Based on this, the adhesion of the outer peripheral surface of the aluminum pipe 14 to the inner peripheral surface of the fitting hole 19 can be improved, the fixing strength between the aluminum pipe 14 and the flange member 12 can be increased, and the outer peripheral surface of the aluminum pipe 14 can be fitted. It is possible to satisfactorily prevent or suppress crevice corrosion caused by a gap between the inner peripheral surface of the hole 19.

  In addition, when the sacrificial corrosion layer 34 is formed on the surface of the resin 32, the aluminum pipe in the fitting portion between the aluminum pipe 14 and the fitting hole 19 is compared with the case where the flange member 12 is simply made of resin. 14 crevice corrosion can be more effectively suppressed or prevented.

An aluminum pipe 14 (outside diameter φ16.0 mm) is inserted into the fitting hole 19 (hole diameter φ16.1 mm) of the flange member 12, and the aluminum pipe 14 is expanded from the inside at the fitting hole 19 portion, and the aluminum pipe 14 Was assembled to the flange member 12 to form the pipe flange joint 10.
As the aluminum pipe 14, an extruded material of A6063 of JIS H 4040 was used. The composition is as shown in Table 1.

About the flange member 12, the structure was made into various structures as shown in Table 2, and the corrosion test was implemented about each.
Here, the corrosion test was a salt water corrosion test, and the corrosion state of each pipe flange joint 10 after 2000 hours was observed.

  In Table 2, “corrosion due to liquid pool” refers to corrosion that occurs when a liquid pool is generated in the portion indicated by A in FIG. 2 (B).

  In each of the embodiments, the sacrificial corrosion layer 34 made of metal is formed by spraying metal particles onto the surface of the resin 32 at a high speed so as to be embedded in the surface of the resin 32 and coating the surface with the sacrificial corrosion layer 34. Adopted the method to do.

  The compositions of ADC12, ZDC2, and MS1 in Table 2 are as shown in Table 1.

As can be seen from the results in Table 2, in Comparative Example 1 in which the flange member 12 is made of an A6063 extruded material, corrosion of the aluminum pipe 14 occurs, and Comparative Example 2 in which the flange member 12 is made of aluminum die cast (ADC12). Then, the degree of corrosion of the aluminum pipe 14 is further increased.
In these cases, corrosion on the flange member 12 side does not occur.
That is, in Comparative Example 1 and Comparative Example 2, the aluminum pipe 14 corrodes preferentially.

On the other hand, in Comparative Example 3 in which the flange member 12 is made of zinc alloy die cast (ZDC2), which is an electrically base metal than the aluminum pipe 14, no corrosion occurs on the aluminum pipe 14 side. The side is preferentially corroded.
In Comparative Example 3, the corrosion proceeds until reaching the inner surface of part of the fitting hole 19.

  Further, in Comparative Example 4 in which the flange member 12 is made of a magnesium alloy extruded material (MS1), the magnesium alloy extruded material is electrically base with respect to the aluminum pipe 14, so that corrosion occurs on the aluminum pipe 14 side. The flange member 12 side was preferentially corroded, and the degree of corrosion was corroded until the aluminum pipe 14 reached the inner surface of the fitting hole 19 as the aluminum pipe 14 was rotated in the fitting hole 19.

  On the other hand, in the first embodiment, the flange member 12 is made of a resin 32 (here, polypropylene resin) alone, and in this first embodiment, not only the flange member 12 but also corrosion inside the fitting hole 19 of the aluminum pipe 14 occurs. Although there was no corrosion, a portion of the corrosion indicated by A in FIG.

Next, in Example 2 in which zinc was coated as the sacrificial corrosion layer 34 on the surface of the resin 32, corrosion of the zinc coating layer, that is, the sacrificial corrosion layer 34 occurred, and corrosion inside the fitting hole 19 of the aluminum pipe 14 did not occur. However, corrosion due to a slight liquid accumulation occurred in the portion indicated by A in FIG.
The corrosion due to the liquid pool was smaller than that in Example 1.

In Example 3, instead of zinc in Example 2, magnesium was coated on the surface of the resin 32 as a sacrificial corrosion layer 34. In Example 3, magnesium is more electrically base to zinc. Therefore, no corrosion was observed on the aluminum pipe 14 side.
On the flange member 12 side, only the magnesium coating layer, that is, the sacrificial corrosion layer 34 was corroded.

  In Example 4, the thickness of the sacrificial corrosion layer 34 made of magnesium was reduced to 0.01 mm or less as compared to Example 3, and in this Example 4, the life of the anticorrosion effect due to sacrificial corrosion in the sacrificial corrosion layer 34 was short, In the portion indicated by A in FIG. 2 (B), the aluminum pipe 14 was corroded by a slight liquid pool.

  In Example 5, the sacrificial corrosion layer 34 of magnesium was formed with a thickness of 0.60 mm, and in this Example 5, the thickness of the sacrificial corrosion layer 34 was thicker than 0.50 mm, which is the upper limit value of the desired thickness. The sacrificial corrosion layer 34 was cracked and dropped off around the aluminum pipe 14 due to deformation of the aluminum pipe 14 when the pipe was expanded, so that the corrosion prevention effect due to sacrificial corrosion in the sacrificial corrosion layer 34 was lowered.

  As described above, according to the present embodiment, the problem of corrosion in the pipe flange joint 10 can be solved satisfactorily.

Although the embodiments and examples of the present invention have been described in detail above, these are merely examples.
For example, the sacrificial corrosion layer 34 in the flange member 12 is necessary for a portion around the aluminum pipe 14, but it is not necessarily formed over the entire surface of the flange member 12. The present invention can be configured in various forms without departing from the spirit of the present invention.

It is a figure which shows the piping flange joint which is one Embodiment of this invention. It is a figure which shows an example of the conventional piping flange joint.

Explanation of symbols

10 Piping flange joint 12 Flange member 14 Aluminum pipe (piping member)
19 Fitting hole 32 Resin (insulating material)
34 Sacrificial corrosion layer

Claims (2)

A fitting hole that penetrates in the plate thickness direction is formed in a plate-like flange member, and a metal pipe member is fitted into the fitting hole so that the tip projects from the plate surface of the flange member. In piping flange joints assembled to
A piping flange joint, wherein the flange member is made of a resin which is an insulating material.   2. The pipe flange joint according to claim 1, wherein a sacrificial corrosion layer made of a metal that is electrically lower than the pipe member is coated on a surface of the flange member excluding an inner surface of the fitting hole. .

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