JPH0783045A - Oxygen sensor boss - Google Patents

Abstract

PURPOSE:To provide an oxygen sensor boss using a boss member by means of cold casting work of a low cost which can be easy welded along the oxygen sensor installing surface of an exhaust pipe. CONSTITUTION:An oxygen sensor boss is weld-formed by connecting to an installation hole opened to the installation surface of an exhaust pipe. A boss main body 1 having raising part 3 for positioning to the installation hole and a saddle shaped flange part 2 welded along an installation surface, and in the central area of which a female screw hole 5 is formed, is made of a stainless steel formed in a cold casting appliance which consists of 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: 150ppm with weight ratio %, Fe and non-avoidable impurity in the rest.

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 into a mounting hole formed 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 on a mounting surface of the exhaust pipe. The boss member for forming such an oxygen sensor boss has a complicated shape because it is welded so as to be correlated and connected along the oxygen sensor mounting surface of the exhaust pipe, and the exhaust gas heat is constantly applied during operation. Since it is exposed, it must have excellent heat resistance and corrosion resistance. Therefore, in the past, SUS
It is common to use stainless steel such as 304 as a raw material, which is manufactured by precision casting by the lost wax method, which has low productivity, but the cost is high, and there is a problem in strength due to defective casting.

From these reasons, an attempt was also made to manufacture a cold-pressed product which can be manufactured while maintaining high productivity and is also excellent in strength. FIG. 5 shows, as an example thereof, a deformed flange portion 12 contacting along an attachment surface of an exhaust pipe is formed by cold forging integrally with a tubular body portion 14, and a female screw hole 15 for mounting a sensor screw is formed in the center portion thereof. It was 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. Therefore, it is necessary to be “large”, whereas the loads F ₁ and F ₁ applied to the left and right parts of the figure are “small”, and the imbalance between these loads F ₁ and F ₂ acts as an unbalanced load.
Therefore, even if austenitic stainless steel for cold forging, which is used for cold press working such as SUSXM7, is used as a material, the boss member has a high work hardening rate, frequent cracking, and poor yield. It was found that the life of the press die was significantly reduced due to the unbalanced load and it was not practical, and the weld nut for forming the oxygen gas sensor boss of the cold forged product was not manufactured yet, and precision casting was performed despite the high cost. The one manufactured by is used.

[0004]

The problem to be solved by the present invention is to solve the above-mentioned problems, and it is easy to weld along the oxygen sensor mounting surface of the exhaust pipe, and the strength is improved. Another object of the present invention is to provide an oxygen sensor boss that uses a boss member of a cold forged product, which is excellent and is low in cost.

[0005]

The 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 being connected to a mounting hole opened in a mounting surface of an exhaust pipe. A boss main body having a raised portion fitted into the mounting hole and positioned, and a saddle-shaped brim portion contacting along the mounting surface, and a female screw hole for sensor screwing formed in the central portion, % By weight, 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.
0-3.5%, N: 150ppm or less and the balance Fe
And a cold forged product made of stainless steel composed of unavoidable impurities as a raw material.

[0006]

In this oxygen sensor boss, an oxygen gas sensor is attached to the central female screw hole, as in the conventional oxygen sensor boss.

The present invention is characterized in that the boss main body formed on the exhaust pipe is formed by a cold forged product made of the special stainless steel having good cold workability as described above. However, it is extremely important that the Ni content is 10.0 to 11.5%. That is, when the Ni content is less than 10.0%, the cold workability can hardly be improved, and 11.5
If it exceeds%, the strength of the product may decrease, which is not preferable. In this way, Ni is contained in the above range, and C is 0.01% or less and N is 150 ppm or less (C +
N = 0.025% or less), the deformability of the metal element improves during press working and the work hardening rate decreases, so even though it is a cold forged product with a complicated shape, it can be pressed. Cracks due to processing are reliably prevented.

As described above, the Ni content is 10.0 to 1
Although cracking during cold working can be suppressed by setting the content to 1.5%, it is necessary to reduce S in steel, which affects the cracking susceptibility, so that the Ni content falls within the above range. That is, since S combines with Mn in steel to form an intermetallic compound MnS, cracking may occur from the starting point of MnS during cold working. Therefore, S is 0.00 or more as described above.
It is extremely important that the amount of MnS is suppressed to 1% or less. That is, this value is an extremely small amount of about 1/30 or less of that of SUSXM7 which is a conventional austenitic stainless steel material for cold forging. The content of S is 0.0
If it exceeds 01%, the amount of MnS produced increases and cracks occur frequently, and if the amount of S decreases, the amount of MnS produced decreases correspondingly, and good results are obtained. As described above, the less MnS is produced, the more preferable it is. Therefore, the less Mn content in the steel is, the less MnS is produced and the fewer cracks are generated during cold working. However, it is stable on an industrial scale and under normal conditions. The upper limit of the Mn content is SUS.
It is set to 1.0% or less, which is about ½ of XM7.

The contents of Cr and Cu have functions such as corrosion resistance and heat resistance as stainless steel. Therefore, Cr: 18 to 20%, Cu: 3.0 to 3.5.
% Is included.

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% as described above, S
i: 0.5% or less, Mn: 1.0% or less, P: 0.04
% Or less, S: 0.001% or less, Ni: 10.0 to 1
1.5%, Cr: 18.0 to 20%, Cu: 3.0 to
A stainless steel wire rod containing 3.5%, N: 150 ppm or less and the balance of Fe and unavoidable impurities was cut and coarsely formed by a nut homer to obtain a roughly formed product 11 having a shape as shown in FIG. Mold.

Next, the rough-formed product 11 is softened by vacuum annealing to apply a lubricating oil, and a primary-formed product 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, coated with lubricating oil, and then molded into a secondary molded product 13 having a shape as shown in FIG. The secondary molded product 13 thus obtained 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 brim 2 which is welded along the oxygen sensor mounting surface of the exhaust pipe. 3 is formed, and a body portion 4 having a diameter substantially the same as that of the raised portion 3 and a short columnar center boss 15 are formed on the front side, so that the center boss 15 portion of this secondary molded product 13 is formed. A short cylinder that can be positioned by fitting it into the oxygen sensor mounting hole of the exhaust pipe if the tapped hole is punched and the end surface processing and tap cutting are performed to form the female screw hole 5 for sensor screwing. The body portion 4 is connected to the ridge-shaped raised portion 3 through the saddle-shaped collar portion 2 that is in contact with the mounting surface, and the female screw hole 5 for sensor screwing is provided in the center portion thereof.
The boss main body 1 of the cold forged product as shown in FIG.

The boss member thus obtained is mounted on the exhaust pipe while fitting and positioning the raised portion 3 of the boss main body 1 in the mounting hole of the oxygen sensor of the exhaust pipe, similarly to the conventional boss member of this kind. By welding the exhaust pipe with the saddle-shaped brim 2 along the surface, the oxygen sensor boss is formed in the exhaust pipe, so the oxygen sensor is screwed to the female screw hole 5 in the center. You can use it.

[0013]

EXAMPLES Next, Examples of the present invention and Comparative Examples are shown in Table 1.
Described in. In this example, a special stainless steel wire material having the composition shown in the table was first roughly formed into a shape as shown in FIG. 2 and then vacuum annealed at 1050 ° C. for 60 minutes, and then -17.
After cooling with N _{2 at} ℃ / min, lubricating oil was applied, followed by primary press molding with a 400-ton press into a shape as shown in FIG. 3 and vacuum annealing at 1050 ° C. × 60 min, N at -17 ° C./min.
₂ After cooling, apply lubricating oil, and after secondary press molding with a 400 ton press into a shape as shown in Fig. 4, punch tapped hole punching and finish processing such as end face processing and tap cutting The boss mainly has a shape of 35 mm and an upper curvature R27 as shown in FIG. In addition, this boss main body is manufactured at a speed of 500 pieces / hour by using a single-piece mold. On the other hand, the comparative example is SUSXM7
This is the case when the material is. In addition, 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 apparent from the above description, the present invention is fitted into a saddle-shaped collar portion to be welded along the mounting surface of the oxygen sensor of the exhaust pipe and the mounting hole formed in the mounting surface. Since the boss mainly having a ridge for positioning and a female screw hole formed in the center is a cold forged product made of special stainless steel, it is attached to the oxygen gas sensor mounting surface of the exhaust pipe with the ridge. It is a cold forged product that can be welded accurately and easily along the saddle-shaped collar while positioning it in the hole, and because it is a cold forged product, it is of high quality with excellent strength, and the life of the press die is long. Since the productivity is remarkably improved, the cost can be reduced, and the cracks during the press working are extremely small, so that the yield is improved. Therefore, the present invention contributes to the industry as a solution to the problems of the conventional oxygen sensor boss, and is extremely large.

[Brief description of 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 molded product in a manufacturing process of 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 of a boss member prototyped by cold pressing is applied.

[Explanation of symbols]

 1 Main boss 2 Saddle-shaped collar 3 Positioned ridge 5 Female screw hole

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Jun Sakai, 1-4-1, Chuo, Wako-shi, Saitama, Honda R & D Co., Ltd. (72) Inventor, Yoshiyuki Gushiken 1-4-1, Wako-shi, Saitama (72) Inventor Tadaomi Shirahashi 1-59, Fukuike, Tenpaku-ku, Nagoya, Aichi Prefecture (72) Inventor Hiroshi Kajino 1-8, Takahashi, Oguchi-cho, Niwa-gun, Aichi Prefecture Aoyama Manufacturing Company ( 72) Inventor Akira Tokaibayashi 1-8 Takahashi, Oguchi-cho, Niwa-gun, Aichi Prefecture Aoyama Manufacturing Co., Ltd.

Claims (1)

[Claims] 1. An oxygen sensor boss, which is welded and formed by being connected to a mounting hole opened in a mounting surface of an exhaust pipe, and a raised portion (3) fitted and positioned in the mounting hole.
And a boss main body (1) having a saddle-shaped collar portion (2) contacting along the mounting surface, and a female screw hole (5) for sensor screwing formed in the central portion, in% by weight. 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 to 20%, Cu: 3.0 to
An oxygen sensor boss, which is a cold forged product made of stainless steel containing 3.5% and N: 150 ppm or less and the balance being Fe and inevitable impurities.