JP2960557B2 - Profiled wire for oil ring of internal combustion engine and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a steel two-piece type oil ring for sectional profile wire arrangement used for various internal combustion engine
A method of manufacturing a Niso.

[0002]

2. Description of the Related Art A steel oil ring for an internal combustion engine is conventionally of a three-piece type consisting of two rings of two rectangular cross sections and one spring, and a new type.
There are two types, a two-piece type consisting of a total of two deformed grooved rings and one spring. In recent years, there has been an increasing demand for switching from a three-piece type to a two-piece type for the purpose of cost reduction by reducing the number of parts. The sectional shape of the two-piece type grooved ring is substantially H or X
It has a complicated character shape, and the ratio of the thickness dimension of the web part connecting the left and right parts to the total thickness dimension of the left and right parts is small and the degree of irregularity is large. In recent years, there has been an increasing demand for high alloying for the purpose of improving wear resistance, scuff resistance, sulfuric acid corrosion resistance, and the like. Of the piston rings, the pressure ring has a cross-sectional shape close to a simple rectangle, so there are few manufacturing problems, and it has already been highly alloyed to 17Cr martensitic stainless steel. The rails (commonly called side rails) of the three-piece combined oil ring are SU
S420J2 (0.35C-13Cr-based) or 0.65C-13Cr
Although martensitic stainless steel is used, the cross-sectional shape is still close to a simple rectangle, and it can also be manufactured by a conventional cold rolling or cold drawing method. As a side rail for 3-piece type, Japanese Patent Publication No. 61-5486
No. 2 (0.65C-13Cr-based) and Japanese Patent Application Laid-Open No. 61-59066 (0.55C-7Cr-based) have been proposed.

[0003]

There is a strong demand for the material of the oil ring to be made of a high alloy. Particularly for a two-piece oil ring, the higher the alloy, the higher the wear resistance, scuff resistance and corrosion resistance can be expected. However, it is not possible to increase the C of the two-piece oil ring with a deformed groove for a two-piece oil ring from a martensitic stainless steel containing more than 0.8% by weight of C and 15% by weight or more of Cr, for example. Very difficult. That is, the ring has a complicated cross-sectional shape and a large degree of irregularity, that is, a large difference in shape from a circle or a rectangle. The web part and the flange part which is not subjected to a compressive action from the upper and lower sides are adjacent to each other. As a result of experiments by the present inventors, it has been found that cracks are very likely to occur from this boundary part and that the oil ring has This is because the surface roughness is not more than 3S and the surface properties such as cracks, scratches, and scratches are strictly regulated. That is, according to the conventional cold drawing method, the workability is reduced due to the high alloying, the deformability is large, and the work crack occurs at the boundary between the web portion and the flange portion as described above. In order to prevent these problems, the working ratio per pass or annealing is limited to a low value. As a result, the number of working passes and the number of annealings to reach a final product are further increased, and these processes or Surface properties are easily damaged during handling, and cost is also difficult. For this reason, the conventional C 0.8
No two-piece oil ring has been produced from martensitic stainless steel containing more than 15% by weight of Cr and more than 15% by weight. The present invention relates to a novel manufacturing method and a cross-sectional structure for a two-piece oil ring made of a high alloy steel which is excellent in wear resistance, scuff resistance and sulfuric acid corrosion resistance.
It is intended to provide a shaped wire . The present invention makes it possible for the first time to manufacture and provide a high alloy oil ring having a complicated cross-sectional shape.

[0004]

According to the present invention, the chemical composition of the base material contains, by weight%, more than 0.8% and less than 0.95% of C, less than 1.0% of Si, less than 1.0% of Mn, and 15.0 to 20.0% of Cr. Fe
And a quenching and tempering hardness of HV300 to 450, a cross-sectional shape of approximately H or X-shape, and a ratio of the thickness of the web portion connecting the left and right portions to the total thickness of the left and right portions. Is 0.3 or less, and the surface roughness is
A cross-sectionally shaped wire rod for an oil ring of an internal combustion engine , which is not more than 1.4 µmRmax , or one or two of Mo and W are added to the above composition in an amount of 0.5 to 3.0% by weight of Mo + 1 / 2W;
One or two kinds of V and Nb are V + 1 / 2Nb in 0.05 to 2.0 weight.
%, And 1.6 to 5 % by weight of Ni , the balance being Fe and unavoidable impurities, and a martensitic stainless steel containing more than 0.8% by weight and less than 0.95% by weight of C and 15% to 20% by weight of Cr. In this order, a step of plastically working a steel wire material by a driven or non-driven roll die, a step of cold working by a driven or non-driven roll die, and a step of quenching and tempering by a continuous heat treatment apparatus. A method for producing a profiled wire rod for an oil ring of an internal combustion engine, the method comprising:
The production method of the present invention can be widely applied to any martensitic stainless steel containing more than 0.8% by weight and less than 0.95% by weight of C and 15% to 20% by weight of Cr. To give a more specific example, the composition other than C, Cr, and Fe may be such that the deoxidizing elements Si and Mn are each 1.0% or less, or one or two of Mo and W are Mo + 1 / 2W at 0.5%. ~ 3.0% by weight, V
+ 1 / 2Nb 0.05-2.0% by weight, and 12% by weight or less of Co,
For example, steel containing 1.6 to 5 % by weight of Ni as appropriate. That is, the present invention is a method of manufacturing a novel oil ring for profiled wire around the use of roll-dies warm, and the first time brought about an internal combustion institutions made of <br/> high alloy steel by the manufacturing method Cross section for oil ring with irregular cross section
It is a wire .

[0005]

First, the manufacturing method of the present invention will be described.
According to the method invention of the present application, the use of a roll die eliminates the need for a strong lubricant such as a metal soap in a solid hole type die. Conventionally, it has been difficult to remove this lubricant after each drawing step. Sufficient, it can prevent surface roughening that occurred during intermediate annealing and maintain a high level of surface properties, and the adoption of warm working reduces the deformability due to the use of high-alloy steel, which tends to cause cracking. Material
Cracking was prevented, and working strain was not accumulated in a predetermined cross-sectional shape with a large degree of irregularity. Therefore, it was possible to form efficiently without intermediate annealing. Further, the warm working method using a roll die has a large effect of raising the meat into the roll die, so that it is possible to form a sharp (small parting radius of the protruding portion) cross-sectional shape. The warm working temperature is preferably set as high as possible within a range where the quenching effect does not occur, so that the effect of the warm working (the above-described intermediate annealing becomes unnecessary or the number of times is reduced) is sufficiently brought out. Regarding the heating method, the high-frequency induction heating method is preferable because there is no danger of sparks and rapid heating can be performed, so that the surface properties due to oxidation or the like are hardly impaired. Further, the production method of the present invention includes a cold working step using a roll die, but since this step does not require a strong lubricant such as metal soap as in the case of the above-described warm, the surface roughness is reduced. While achieving a predetermined dimensional accuracy. In both of the above-mentioned steps, the drive method using the roll dies is more excellent in terms of prevention of bulging of meat, generation of cracks, and workability. However, the method of the present invention can be sufficiently achieved even with a non-driving method.

[0006] The deformed wire after the warm working and the cold working by the roll die is punched and pierced with oil holes in the web (see Fig. 1), degreased, and then subjected to continuous quenching and tempering in which a protective atmosphere is introduced. The apparatus is heat-treated to a predetermined hardness in the range of 300 to 450 HV. Usually, it is handed over to a piston ring maker in this state. The heat treated product by the continuous heat treatment furnace has extremely high uniformity in the length direction, which suppresses the spring back unevenness in the curling process,
Helps ensure a uniform bent shape. Next, in the deformed wire rod of the present application, the ratio of the thickness of the web to the total thickness is defined to be 0.3 or less, because if it exceeds this value, it is somewhat difficult with the conventional manufacturing method, but it can be manufactured. Yes, on the other hand, satisfying this value, as well as satisfying the surface properties, is a major problem in the production of the deformed wire,
This is because the production of a high alloy wire rod has become feasible for the first time by the method of the present invention.

[0007] Also, the reason that the hardness range is specified as HV300 to 450 is that when the hardness exceeds HV450, the springback becomes large in the curling process, and it becomes difficult to keep the curling shape within a certain range. This is an essential condition particularly for producing a cross-sectionally deformed wire for an oil ring having a deformed cross-section according to the present invention. On the other hand, if it is less than HV300, the wear resistance is reduced contrary to the purpose of high alloying, and a predetermined ring life cannot be obtained. After bending, the deformed wire rod of the present invention has a sliding surface and an end surface thereof, that is, a surface in contact with a wall surface of a ring groove of the piston, which is lightly polished, and a groove on a side which is bent and formed into a ring to become an inner periphery. Since the inner surface of the is directly in contact with the spring as it is, the entire surface must have a surface roughness of 3S or less. This requirement for surface roughness is the first to be obtained industrially stably for a high alloy wire by the invention of the manufacturing method of the present invention as described above.

Next, the reasons for limiting the components of the present invention will be described. C combines with Cr and additional elements such as Mo, W, and V to form carbides, which contributes to the improvement of wear resistance and seizure resistance, and also partially dissolves in the matrix to strengthen the matrix. In order to obtain these effects, C must be added in excess of 0.8%. However, since the oil ring of the present invention has an irregular cross-section, if it is 0.95% or more, even if it is warm working, the productivity of the ring material can be improved. Also, the formability of the ring deteriorates. 0.95%
If it exceeds, excessive carbides are formed, and the sulfuric acid corrosion resistance decreases. Therefore, C exceeds 0.8% and 0.95%
Limited to less than. Si is an element that is added for the purpose of deoxidation during refining of steel and is effective in improving sulfuric acid corrosion resistance. However, if it exceeds 1%, warm workability is impaired.
Is limited to 1% or less. Mn is added for the purpose of desulfurization at the time of refining steel, but if it exceeds 1.0%, it impairs the hot workability at the time of producing a wire, so it is limited to 1.0% or less. Cr is bonded to C as described above to form carbides (M ₂₃ C ₆ type and M ₇ C ₃
Is an essential component for the oil ring of the present invention because it improves the wear resistance and seizure resistance. Further, a part thereof is dissolved in a matrix to improve oxidation resistance and heat resistance. In addition, a hard nitrided layer is generated by the nitriding treatment, and the wear resistance and the seizure resistance are greatly improved. Under the normal environment (when not in a sulfuric acid atmosphere) in order to obtain these effects and not reduce the toughness, for example, as described in JP-A-1-208435, the amount of Cr is sufficiently in the range of 7 to 25%. Although it is possible, the amount of Cr is limited to a narrow range because the conditions are more severe in a sulfuric acid atmosphere. According to the results of experiments by the present inventors, when the Cr content is less than 15.0%, the amount of corrosion and wear in sulfuric acid increases, probably due to insufficient carbide content. On the other hand, if the Cr content exceeds 20.0%, the amount of carbides and the amount of nitrides of Cr are likely to be excessive when nitriding is performed, so that the sulfuric acid corrosion resistance is reduced. Therefore, the Cr content was limited to the range of 15.0 to 20.0%.

Mo and W combine with C to form a carbide of its own, and also form a solid solution in Cr carbide, thereby strengthening it, further increasing the softening resistance in tempering, and increasing the nitriding treatment. Since it contributes to the formation of a nitride layer and improves wear resistance and seizure resistance, it is added as necessary. Mo has an effect of improving sulfuric acid corrosion resistance. In order to obtain the above effect, Mo, W
At least 0.5% of (Mo + 1 / 2W) species or two is required. However, excessive addition reduces toughness,
The upper limit of (Mo + 1 / 2W) was set to 3.0%. V and Nb both refine the crystal grains and contribute to the improvement of toughness.
Like Mo and W, it forms carbides by itself and
By forming a solid solution in the carbide and strengthening it, the wear resistance and seizure resistance are improved, and the tempering softening resistance is improved. Therefore, it can be added for this purpose. In addition, both elements have an effect of improving the sulfuric acid corrosion resistance. To obtain these effects, V and Nb must be 1
At least 0.05% or more of (V + 1 / 2Nb) is required for one or two species. However, if added excessively, MC-type carbides are excessively formed and the toughness is degraded. Therefore, the upper limit of the amount of (V + 1 / 2Nb) is set to 2.0%. Ni is an important element for improving the sulfuric acid corrosion resistance of the nitrided layer in the present invention. Ni does not form carbides, forms a solid solution in the matrix, and enhances sulfuric acid corrosion resistance.
Since the nitride is not formed, its action remains even in the nitrided layer, which is particularly effective for the piston ring material of the present invention which is used after nitriding. Ni
If it exceeds 5.0%, it becomes difficult to obtain a predetermined hardness in the heat treatment, and Ni is set to 5.0% or less. Also get a noticeable effect
In order to achieve this, it is necessary to add 1.6% or more.
1.6 to 5.0% by weight. P, S, O, and N are usually contained in trace amounts as impurity elements.

[0010]

EXAMPLES Table 1 shows the chemical composition of each material for which an oil ring was manufactured by the invention of the invention such as abrasion resistance and the manufacturing method of the present invention and a comparative material. Here, the comparative material is an example of 0.65C-13.5Cr-0.3Mo-0.1V-remainder Fe material conventionally applied to the two-piece type. The production method was tested by removing the surface flaws by shaving the hot-rolled and annealed coil material of about 6 mm in diameter from each of the materials shown in Table 1, then turning it into a wire having a diameter of 4.0 mm by warm drawing, and further driving a four-sided roll. By
A rectangular wire having a rectangular cross section and a round corner was used.
Each of these wire rods was deformed by a series of processing apparatuses whose schematic system diagram is shown in FIG. 2 at a heating temperature of about 800.degree. Further, except that there is no heating device and temperature measuring device, cold finishing is performed by using substantially the same device as in FIG. 2, and a ratio (tw / T) of the web thickness tw to the total thickness T shown in a schematic sectional view in FIG. Of about 0.2 was obtained.

[0011]

[Table 1]

After continuous annealing of the wire manufactured as described above, a crack was checked by eddy current testing. As a result, no crack was recognized including the boundary between the web and the flange. Next, after the oil hole was formed in the web by punching, the web was quenched and tempered in a continuous furnace and subjected to heat treatment. Surface roughness by the stylus method after heat treatment is 0.6
～1.4MyumR m is ax, satisfy the following provisions 3S, also, the dimensional tolerance of each part (the narrowest tolerances 0.06 mm) also was achieved, thereby satisfying. Samples No. 1 to No. 17 in Table 1 were curled into a ring of a specified diameter, cut at the joint, and subjected to nitriding treatment, but could be processed without any problem in any material process. Next, Table 2 shows an example of a result of each test of the scuff resistance, abrasion amount and corrosion and abrasion amount of each material in Table 1 after each nitriding treatment, and each characteristic of the comparative material is set as 100. It is a thing. The test method is shown in FIG.
A Fabry abrasion tester having the test format shown in Table 1 was used.
This is a test material that rotates at 300 rpm.
A sandwiching load is applied between V-blocks. During the test, a wet method in which lubricating oil was dropped was used. After roughing the test material to the specified shape, HRC40 (HV39
The sample was tempered in 2), subjected to a finishing process, and then subjected to a gas nitriding process at 540 ° C. × 20 hours, and was ground to remove a brittle nitride on the outermost layer to obtain a test material. The amount of wear was determined by applying a predetermined load for a predetermined period of time, and measuring the weight loss before and after. The scuff resistance is to gradually increase the load of the V block, and in the process, the occurrence of seizure is sensed by the torque fluctuation of the test pin, and the load at this time is measured. In the corrosion wear test, a difference in weight before and after the test was measured using an oil to which 2.0% sulfuric acid was added as a test lubricant.

[0013]

[Table 2]

From Table 2, it can be seen that the oil ring according to the present invention
For the purpose of improving the wear amount, scuff resistance and corrosion wear resistance, high C and high Cr, and further, W, Mo, V, Nb, N
It can be seen that the purpose is largely achieved by appropriately selecting i and Co and adding them in harmony.

[0015]

As described above, the oil ring of the present invention responds to the demand for performance improvement such as abrasion resistance by using a high alloy, and the workability is reduced by the high alloy. On top of that, as a result of the conversion to the two-piece type, H or X
The present invention has been made possible by applying a new manufacturing method to a case where the shape becomes complicated and the manufacturability is further reduced. This can sufficiently respond to the demand for the performance improvement.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a cross-sectional shape of a two-piece oil ring for an internal combustion engine.

FIG. 2 is a schematic system diagram of a warm roll die processing apparatus used for carrying out the manufacturing method.

FIG. 3 is a diagram showing a wear amount, a scuff resistance, and a mode of a corrosion wear test.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Product or material 1 'Oil hole 2 Unwinding machine 3 Roller straightening machine 4 High frequency heating device 5 Temperature measuring device 6 Driving roll with grooved die 7 Cooling device 8 Drying machine 9 Dimension measuring machine 10 Winding machine 11 Test pin 12 V block

──────────────────────────────────────────────────続 き Continuation of front page (58) Field surveyed (Int. Cl. ⁶ , DB name) F16J 7/00-10/04 F02F 5/00 C22C 38/00 302

Claims (5)

(57) [Claims] 1. The chemical composition of a base material is more than 0.8% and less than 0.95% by weight of C, less than 0.95%, Si 1.0% or less, Mn 1.0% or less, and Cr 15.0.
Containing 残 20.0%, the balance consisting of Fe and inevitable impurities, the quenching and tempering hardness is HV300 to 450, the cross-sectional shape is approximately H or X-shaped, and the thickness of the web portion connecting the left and right portions thereof is The ratio to the total thickness of the left and right parts is 0.3
A cross-sectionally shaped wire for an oil ring of an internal combustion engine , wherein the wire has a surface roughness of 1.4 μmRmax or less . 2. The method according to claim 1, wherein one or two of Mo and W are added to the base metal by adding Mo + 1 / 2W.
Containing 0.5 to 3.0% by weight, the balance being Fe and unavoidable impurities, quenching and tempering hardness of HV300 to 450,
The ratio of the thickness of the web portion connecting the left and right portions thereof to the total thickness of the left and right portions is approximately 0.3 or less, and the surface roughness is 1.4 μm Rmax or less. oil ring sectional profile line of an internal combustion engine, wherein the door
Wood . 3. The element added to the base material further comprises one or two of V and Nb added to V + 1 / 2N on the basis of claim 1 or 2.
b, containing 0.05 to 2.0% by weight, with the balance being Fe and inevitable impurities, and having a quenching and tempering hardness of HV300 to 450
The cross-sectional shape is substantially H or X-shaped, and the ratio of the thickness of the web portion connecting the left and right portions to the total thickness of the left and right portions is 0.3 or less, and the surface roughness is 1.4 μmRmax or less.
Sectional profile for an oil ring for an internal combustion engine, characterized in that that
Wire rod . 4. The element added to the base material further contains 1.6 to 5 % by weight of Ni in addition to any one of claims 1 to 3, and the balance is Fe and unavoidable impurities. The quenching and tempering hardness is HV300 to 450, the cross-sectional shape is substantially H or X-shaped, and the ratio of the thickness of the web portion connecting the left and right portions to the total thickness of the left and right portions is 0.3 or less, A cross-sectionally shaped wire for an oil ring of an internal combustion engine , having a surface roughness of 1.4 μmRmax or less . 5. The method according to claim 5, wherein the content of C is more than 0.8% by weight and less than 0.95% by weight.
A wire material of martensitic stainless steel containing 15% by weight to 20% by weight, a step of warm plastic working by a driven or non-driven roll die, a step of cold working by a driven or non-driven roll die, and 5. The method according to claim 1, further comprising a step of performing quenching and tempering by a continuous heat treatment apparatus in this order .
The method for producing a cross-sectionally shaped wire rod for an oil ring of an internal combustion engine according to the above .