JP4199596B2 - Deformed wire rod with groove for pressure ring - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a grooved deformed wire suitable for a pressure ring that prevents leakage of high-temperature and high-pressure gas generated in a combustion chamber, among piston rings for internal combustion engines.
[0002]
[Prior art]
The pressure ring is required to have abrasion resistance, durability, and seizure resistance as its characteristics. This is because if the gas leakage prevention function is impaired and the gas leakage increases, the heat load around the pressure ring increases, the lubricity deteriorates, and cracks in the peripheral members occur.
[0003]
Generally, as a means for improving the above characteristics, a surface treatment is employed in which a sprayed coating is formed by spraying powder or particles of an alloy material on a sliding surface of a pressure ring. However, since the adhesion strength of the thermal spray coating is relatively low, peeling and dropping off of the thermal spray coating may occur during operation in an internal combustion engine that is subjected to a large heat load due to high-speed operation in a high-temperature gas atmosphere.
[0004]
Therefore, as a conventional technique, in order to improve the adhesion of the thermal spray coating, as shown in FIG. 3 (a), an annular groove having a cross-sectional shape expanding in the outer peripheral direction is provided on the sliding surface, and an alloy is used to fill the annular groove. There is a piston ring obtained by plasma spraying a material (see, for example, Patent Document 1).
The surface of the sprayed coating is ground (usually about 0.1 mm) after spraying in order to provide smoothness of the sliding surface. For this reason, when the cross-sectional shape of the annular groove is an inverted trapezoidal shape or an arc shape, the tip end thickness of the rail portions above and below the annular groove increases. Therefore, in order to eliminate the increase in the thickness of the tip of the rail portion and to secure the adhesion strength of the sprayed coating, as shown in FIG. A piston ring in which a groove is provided and a sprayed layer formed by plasma spraying is formed in the annular groove has also been proposed (see, for example, Patent Document 2).
[0005]
[Patent Document 1]
Japanese Patent Laid-Open No. 55-69742 (page 6, FIG. 1, FIG. 3, FIG. 8, FIG. 9)
[Patent Document 2]
Japanese Utility Model Publication No. 4-25066 (page 8, FIGS. 1 and 2)
[0006]
By the way, at present, a grooved deformed wire having a thickness corresponding to the width of the pressure ring of 1.25 to 1.55 mm is generally used as the ring material. The pressure ring is a piston ring maker that uses a grooved deformed wire purchased from a wire maker to form a ring with a nominal diameter of the required dimensions and a free mating clearance-spraying on the sliding surface-spraying It is manufactured through each step of grinding to make the film a smooth surface.
[0007]
[Problems to be solved by the invention]
However, in recent years, internal combustion engines tend to increase in heat load due to high-speed operation, high compression, and measures against exhaust gas. As a result, pressure rings are exposed to increasingly harsh operating environments. Moreover, since the thermal spraying cost occupies the highest ratio in the ring manufacturing cost, in order to reduce the thermal spraying cost, a reduction in the thermal spraying amount of the alloy material has been studied.
Against this backdrop, piston ring manufacturers have recently requested wire rod manufacturers to develop deformed wire rods with a thickness of around 1 mm in order to improve pressure ring characteristics and reduce thermal spraying costs. It has come to be.
[0008]
Theoretically, when the thickness of the wire is reduced, the groove is relatively small, and the amount of thermal spraying of the alloy material embedded in the groove is reduced. However, technically, as the thickness of the wire becomes thinner, grooving becomes extremely difficult, and using only a rolling roller similar to the shape of a conventional rolling roller and having only a small size is around 1 mm. It was not possible to groove the wire. As a result, there has not been a deformed wire for a pressure ring with a thickness of around 1 mm having a groove capable of embedding a spray amount sufficient to exhibit sufficient wear resistance for a long time.
[0009]
The present invention has been made in order to meet recent development demands, and by reducing the contact area between the tip of the rail portion without the sprayed coating and the inner surface of the cylinder liner, the characteristics of the pressure ring are improved. It is an object of the present invention to provide a grooved deformed wire having a thickness of 0.80 to 1.20 mm that can reduce the amount of thermal spraying and achieve a reduction in thermal spraying cost.
[0010]
[Means for solving the problems]
In order to solve the above-mentioned problems, the grooved deformed wire rod for pressure ring of the present invention comprises a groove portion that is continuous with the upper and lower rail portions in the longitudinal direction of the side surface that becomes the sliding surface of the pressure ring, and the thickness a is 0. It is a deformed wire rod of 80 to 1.20 mm, and the cross-sectional shape of the groove is such that the cross-sectional area is within a certain range, with the straight bottom portion, the inner inclined surface of the upper and lower rail portions, and the curved corner portion connecting them. Concerning what was composed.
[0011]
In the present invention, “upper and lower” means “upper” and “lower” in the positional relationship when the pressure ring is mounted in the ring groove.
In addition, that the cross-sectional area is in a certain range means that the sprayed coating made smooth by grinding after spraying has a thickness and a width that can exhibit wear resistance for a long time.
[0012]
The present invention, a groove of a specific cross-sectional shape having a sectional area of a range, the tip thickness b less than 0.15mm or 0.08mm upper and lower rail section, each inclination angle θ of the inner inclined surfaces of the upper and lower rail portion This can be achieved by setting 17 ° to 21 °, the radius of curvature R of the corner of the curve to 0.2 to 0.3 mm, and the depth c of the groove to 0.20 to 0.29 mm.
[0013]
By the way, the reason for limiting the numerical values in the above configuration is as follows.
The tip thickness b of the upper and lower rail portions is set to 0.08 mm or more and less than 0.15 mm. If the tip thickness b is less than 0.08 mm, the contact area with the inner surface of the cylinder liner is further reduced, but the strength of the upper and lower rail portions is reduced. Deformation tends to occur during ring processing, and if it is 0.15 mm or more, the contact area with the inner surface of the cylinder liner increases, and the opening size of the groove is reduced, making it impossible to obtain the width of the sprayed coating necessary for wear resistance. This is because it becomes difficult to contribute to the improvement of the required characteristics of the pressure ring.
In addition, the reason why each inclination angle θ of the inner inclined surfaces of the upper and lower rail portions is in the range of 17 ° to 21 ° is that when the angle is less than 17 °, the groove is machined into a cross-sectional shape having a cross-sectional area sufficient to embed a necessary spray amount. This is because the biting of the rolling roller becomes nearly vertical, making it difficult to bite, and cracking of the roller tends to occur. Further, if the angle exceeds 21 °, the thickness of the rail portion is increased by grinding after thermal spraying.
Furthermore, the radius of curvature R at the corner of the curved line is in the range of 0.2 to 0.3 mm because the tip angle of the rolling roller that is less than 0.2 mm becomes too small and the rolling roller is difficult to bite, roller cracking, etc. It is because it becomes easy to generate | occur | produce. Further, if it exceeds 0.3 mm, the thickness of the rail portion increases due to grinding after thermal spraying.
The reason why the depth c of the groove is in the range of 0.20 to 0.29 mm is that when the thickness is less than 0.20 mm, the thickness is further reduced by grinding of the sprayed coating, and the thickness necessary for maintaining the wear resistance for a long time. This is because when the thickness exceeds 0.29 mm, the rolling roller is difficult to bite and roller cracking or the like occurs.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings.
[0015]
In FIG. 1, the deformed wire W has a thickness a of 0.80 to 1.20 mm, and has a cross-sectional area within a certain range between the upper and lower rail portions 1 and 2 continuous in the longitudinal direction of one side surface. And a predetermined cross section formed by connecting the straight bottom 3 of a predetermined length and the tip inner inclined surfaces 4 and 5 of the upper and lower rails with curved corners 7 and 8 having a radius of curvature R of 0.2 to 0.3 mm. A groove portion 6 having a shape is formed.
The deformed wire shown in FIG. 1 has a side surface that opposes the side surface that forms the groove and is linear in cross section, but may have a curved shape (called a round edge).
[0016]
The cross-sectional area of the groove 6 is 0.115 to 0.366 mm ² , and this cross-sectional area can be measured by a general image processing apparatus.
Moreover, each tip thickness b of the upper and lower rail portions 1 and 2 is 0.08 mm or more and less than 0.15 mm, and the inclination angle θ of the inner inclined surfaces 4 and 5 of the upper and lower rail portions is 17 ° to 21 °, The depth c of the groove 6 is 0.20 to 0.29 mm.
The tip thickness b of the upper and lower rail portions is, for example, the upper rail portion 1, the straight line 21 connecting the tips of the upper and lower rails 1 and 2, and the extension line 23 of the tip inner inclined surface 22 of the upper rail portion 1. Means the distance from the intersection 24 to the side face 25 of the deformed wire W (see FIG. 3).
[0017]
Next, the irregular shaped wire W with a groove according to this embodiment can be processed by, for example, the following method.
[0018]
The Si-Cr steel wire having a wire diameter of 5.5 mm is repeatedly subjected to annealing treatment and wire drawing processing to reduce the wire diameter to 2.5 mm. Process into track shape. Next, the steel wire having the track shape is rolled from above, below, left and right with a four-direction rolling roll. Of these four-direction rolls, the roll that presses one side surface is provided with a convex portion for groove processing.
In the above four-way rolling, it is not necessary to press once to obtain a desired shape, but gradually increasing the amount of rolling and rolling to the desired shape several times in consideration of the burden on the rolling roller. It is preferable.
In addition, it is more preferable that a plurality of rolling rolls with gradually increasing convex heights are prepared and the depth of the groove is gradually increased by these rolling rollers since the load on the rolling roller is reduced.
[0019]
【The invention's effect】
According to the present invention, since a groove having a specific cross-sectional shape having a predetermined cross-sectional area is formed in the longitudinal direction of the side surface of the deformed wire having a thickness of 0.80 to 1.20 mm, The contact area with the inner surface of the cylinder liner is reduced by about 20% as compared with the conventional case, and the spraying amount is reduced by about 35% as compared with the conventional case, and a pressure ring with further improved wear resistance and durability can be obtained.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an embodiment of a deformed wire rod having a groove for a pressure ring according to the present invention.
FIG. 2 is an enlarged partial cross-sectional view for explaining a thickness of a rail portion of a deformed wire rod with a pressure ring groove of the present invention.
FIG. 3 is a cross-sectional view showing a conventional grooved pressure ring.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Upper rail part 2 Lower rail part 3 Straight bottom part 4, 5 Inner inclined surface 6 Groove parts 7, 8 Curved corner part W Deformed wire

Claims (1)

A groove portion that is continuous with the upper and lower rail portions in the longitudinal direction of the side surface that becomes the sliding surface of the pressure ring is configured, the thickness a is 0.80 to 1.2 mm, and the sectional shape of the groove portion is within a certain range. So that the tip end thickness b of each of the upper and lower rail parts is 0.08 mm or more and 0.0.0 mm or more. Less than 15 mm, each inclination angle θ of the inner inclined surface of the upper and lower rail portions is 17 ° to 21 °, the curvature radius R of the curved corner is 0.2 to 0.3 mm, and the depth c of the groove is 0.20 to 0.0. Deformed wire with groove for pressure ring of 29 mm .

Images