JP3109634B2 - Oxygen sensor boss - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oxygen sensor boss formed by welding a boss member having a female screw hole for mounting a sensor to a mounting hole opened in a mounting surface of an exhaust pipe.

[0002]

2. Description of the Related Art In order to form an oxygen sensor boss on a cylindrical exhaust pipe of an automobile or the like, a boss member having a female screw hole for mounting a sensor screw is welded to a mounting hole opened in a mounting surface of the exhaust pipe. However, the boss member for forming such an oxygen sensor boss has a complicated shape because it is welded so as to be correlated along the oxygen sensor mounting surface of the exhaust pipe. Due to the exposure, it must be excellent in heat resistance and corrosion resistance. For this reason, conventional SUS
It is common to use a stainless steel material such as 304 as a raw material and manufactured by precision casting by a lost wax method, which has low productivity, but this may increase the cost and may cause a problem in strength due to poor casting.

In view of the above, an attempt has been made to produce a cold-pressed product which can be produced while maintaining high productivity and which is excellent in strength. FIG. 5 shows, as an example, a deformed flange portion 12 that is in contact with the mounting surface of the exhaust pipe formed by cold forging integrally with a cylindrical body portion 14, and a female screw hole 15 for mounting a sensor screw is provided at the center thereof. It is formed. F ₂ such boss member in central figure when forging, but heading load F _1, F ₁ on the left and right portions is applied, the maximum upsetting part against upward at the center portion of the load F ₂ FIG. , and therefore should be "large", the load F _1, F ₁ exerted on the left and right portions of FIG hand serves as "small", and imbalance of the load F ₁ and F ₂ are offset load.
Therefore, even if such a boss member is formed from austenitic stainless steel for cold forging used as a material for cold pressing such as SUSXM7, the work hardening rate is high, cracks frequently occur, the yield is low, and the above-mentioned yield is low. Due to the unbalanced load, the life of the press mold was significantly reduced and it was found to be impractical.Weld nuts for forming the oxygen gas sensor boss of cold forged products were not manufactured yet, and despite the high cost, precision casting Is used.

[0004]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, and is easy to weld along the oxygen sensor mounting surface of the exhaust pipe and has a high strength. Another object of the present invention is to provide an oxygen sensor boss using a boss member of a cold forged product which is excellent in cost.

[0005]

An oxygen sensor boss according to the present invention which has solved the above-mentioned problems is an oxygen sensor boss which is welded and formed by connecting to a mounting hole opened in a mounting surface of an exhaust pipe. A boss main body having a raised portion fitted and positioned in the mounting hole, and a saddle-shaped flange portion contacting along the mounting surface, and a central portion formed with a female screw hole for mounting a sensor screw, C: 0.01% or less, Si: 0.5% or less, Mn: 1.0% or less, P:
0.04% or less, S: 0.001% or less, Ni: 10.
0 to 11.5%, Cr: 18.0 to 20%, Cu: 3.
0 to 3.5%, N: 150 ppm or less, the balance being Fe
And a cold forged product made of stainless steel made of unavoidable impurities.

[0006]

Such an oxygen sensor boss is used by attaching an oxygen gas sensor to the central female screw hole like the conventional oxygen sensor boss.

The present invention is characterized in that the main body of the boss formed on the exhaust pipe is formed of a cold forged product made of the above-mentioned special stainless steel having good cold workability. However, it is particularly important to set the Ni content to 10.0 to 11.5%. That is, when the content of Ni is less than 10.0%, the cold workability can hardly be improved.
%, The strength of the product is undesirably reduced. Thus, Ni is contained in the above range, C is 0.01% or less, and N is 150 ppm or less (C +
N = 0.025% or less), the deformability of metal elements is improved during press working, and the work hardening rate is reduced. Cracks due to processing are reliably prevented.

[0008] As described above, the content of Ni is adjusted to 10.0 to 1
By setting the content to 1.5%, cracking during cold working can be suppressed. However, in order to keep the Ni content within the above range, it is necessary to reduce S in steel which affects cracking susceptibility. That is, since S combines with Mn in steel to form an intermetallic compound MnS, a crack may occur from MnS as a starting point during cold working.
It is extremely important that the generation of MnS is suppressed to 1% or less. That is, this value is an extremely small amount of about 1/30 or less of SUSXM7 which is a conventional austenitic stainless steel material for cold forging. When the content of S is 0.0
If it exceeds 01%, the generation of MnS increases and cracks occur frequently. On the other hand, when the amount of S decreases, the generation of MnS decreases and good results are obtained. As described above, the smaller the amount of MnS generated, the more preferable. Therefore, the smaller the Mn content in the steel, the smaller the MnS generated and the less cracking during cold working, but it is stable on an industrial scale under ordinary conditions The upper limit of the Mn content is SUS
1.0% or less, which is about 1/2 of XM7.

[0009] The content of Cr and Cu is 18 to 20% for Cr and 3.0 to 3.5 for Cu because they have functions such as corrosion resistance and heat resistance as stainless steel.
%.

Next, an example of a method of manufacturing a boss member for forming the oxygen sensor boss according to the present invention will be described. First, C: 0.01% or less by weight ratio as described above,
i: 0.5% or less, Mn: 1.0% or less, P: 0.04
%, S: 0.001% or less, Ni: 10.0-1
1.5%, Cr: 18.0-20%, Cu: 3.0-
A stainless steel wire rod containing 3.5%, N: 150 ppm or less and the balance consisting of Fe and unavoidable impurities was cut and roughly formed with a nut former to form a roughly formed product 11 having a shape as shown in FIG. Molding.

Next, the rough molded article 11 is softened by vacuum annealing, and after applying lubricating oil, a primary molded article 12 having a shape as shown in FIG. 3 is formed by a press molding machine. The primary molded product 12 thus obtained is subsequently softened by vacuum annealing, and after applying lubricating oil, is molded into a secondary molded product 13 having a shape as shown in FIG. The secondary molded product 13 obtained in this manner is a short columnar ridge used for positioning at the time of welding on the concave arc surface on the back side of the saddle-shaped flange portion 2 to be welded along the oxygen sensor mounting surface of the exhaust pipe. 3 is formed, and a body portion 4 having substantially the same diameter as the raised portion 3 and a short columnar center boss 15 are formed on the front side. If a female screw hole 5 for mounting a sensor screw is formed in the center part by performing punch hole preparation and finishing processing such as end face processing and tap cutting, a short cylinder that is fitted and positioned in the oxygen sensor mounting hole of the exhaust pipe A torso portion 4 is connected to the body portion 4 via a saddle-shaped flange portion 2 which is in contact with the protrusion portion 3 along the mounting surface, and a female screw hole 5 for mounting a sensor screw is provided in the center portion.
Thus, a boss main body 1 of a cold forged product as shown in FIG. 1 is obtained.

The boss member thus obtained is mounted on the exhaust pipe while fitting the raised portion 3 of the boss main body 1 into the mounting hole of the oxygen sensor of the exhaust pipe in the same manner as the conventional boss member of this type. If the saddle-shaped flange 2 is welded to the mounting surface of the exhaust pipe along the surface, an oxygen sensor boss is formed on the exhaust pipe. Then, the oxygen sensor is screwed into the central female screw hole 5 and screwed. And use it.

[0013]

EXAMPLES Next, Examples of the present invention together with Comparative Examples are shown in Table 1.
It describes in. In this example, first, a special stainless steel wire having the composition shown in the table was roughly formed into a shape as shown in FIG. 2 and then vacuum-annealed at 1050 ° C. for 60 minutes to obtain -17.
After cooling with N _{2 in} ° C./min, lubricating oil was applied, followed by primary press molding into a shape as shown in FIG. 3 using a 400-ton press, followed by vacuum annealing at 1050 ° C. × 60 min.
₍₂₎ After cooling, apply lubricating oil, and after secondary press molding with a 400-ton press into the shape shown in Fig. 4, tap tap hole punching, and finish processing such as end face processing and tap cutting are performed. The main body is a boss having a shape as shown in FIG. The boss body was manufactured at a speed of 500 pieces / hour using a single-piece mold. On the other hand, the comparative example is SUSXM7
This is the case where the material is. In the table, the defective rate is represented by the number of defective products due to cracking when 100 pieces are manufactured in each example.

[0014]

[Table 1]

[0015]

As is clear from the above description, the present invention is characterized in that a saddle-shaped flange welded along the mounting surface of the oxygen sensor of the exhaust pipe and the mounting hole opened in the mounting surface are fitted. A boss that has a raised part for positioning and a female screw hole is formed in the center part is a cold forged product made of special stainless steel, so it is mounted on the oxygen gas sensor mounting surface of the exhaust pipe with a raised part Welding can be performed accurately and easily along the saddle-shaped flange while being positioned in the hole, and since it is a cold forged product, it has high strength and excellent quality, and the service life of the press die is long. In addition, the productivity is remarkably improved, so that the cost can be reduced, and further, there is an excellent effect that cracks during press working are extremely small and the yield is improved. Therefore, the present invention has an extremely large contribution to the industry as a solution to the problem of the conventional oxygen sensor boss.

[Brief description of the drawings]

FIG. 1 is a partially cutaway perspective view showing an embodiment of a boss member according to the present invention.

FIG. 2 is a cross-sectional view of a roughly formed product in a process of manufacturing a boss member according to the present invention.

FIG. 3 is a partially cutaway front view of an intermediate primary molded product of a boss member according to the present invention.

FIG. 4 is a partially cutaway front view of an intermediate secondary molded product of a boss member according to the present invention.

FIG. 5 is an explanatory diagram showing a state in which a forging load is applied to a boss member experimentally produced by cold pressing.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Boss main body 2 Saddle-shaped flange part 3 Ridge part for positioning 5 Female screw hole

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yoshiyuki Gushiken 1-4-1 Chuo, Wako City, Saitama Prefecture Inside Honda R & D Co., Ltd. (72) Inventor Tadaomi Shirahashi 1-59 Fukuike, Tenpaku-ku Nagoya-shi 72) Inventor Hiroshi Kajino 1-8-1, Takahashi, Oguchi-machi, Niwa-gun, Aichi Prefecture Inside Aoyama Seisakusho Co., Ltd. 63-147520 (JP, U) JP 2-67024 (JP, U) JP 5-77742 (JP, B2) (58) Field surveyed (Int. Cl. ⁷ , DB name) F01N 7/00 C22C 38/00 302 F01N 7/08 F02D 35/00 368

Claims (1)

(57) [Claims] An oxygen sensor boss connected to a mounting hole opened in a mounting surface of an exhaust pipe and formed by welding, wherein a raised portion (3) fitted and positioned in the mounting hole.
A boss main body (1) having a saddle-shaped flange (2) in contact with the mounting surface, and having a female screw hole (5) formed at the center thereof for mounting a sensor screw. C: 0.01% or less,
Si: 0.5% or less, Mn: 1.0% or less, P: 0.0
4% or less, S: 0.001% or less, Ni: 10.0 to 1
1.5%, Cr: 18.0-20%, Cu: 3.0-
An oxygen sensor boss characterized by being a cold forged product made of stainless steel containing 3.5%, N: 150 ppm or less and the balance being Fe and unavoidable impurities.