JPS61130458A - Piston ring - Google Patents

Abstract

PURPOSE:To improve wear resistance and scuffing resistance, by incorporating prescribed percentage of C, Cr, Mo, V, W, and Fe. CONSTITUTION:The piston ring consists of, by weight, 0.7-1.1% C, 3-6% Cr, 4-6% Mo, 1-2.5% V, 5-8% W, and the balance Fe. This piston ring has superior scuffing resistance as well as sufficient wear resistance without application of hard chrome plating.

Description

[Detailed description of the invention] B. Industrial application field The present invention relates to an improved piston ring.

Prior Art In recent years, as internal combustion engines have become lighter and have higher output, the quality required for piston rings has become more advanced.Currently, spring steel and other materials are used as materials for piston rings. It does not necessarily satisfy the various characteristics required as such. Furthermore, many of today's piston rings are plated with hard chrome to improve wear resistance, but the plating process takes a long time and waste liquid treatment is a cause of high costs, so plating is not recommended. It is desired to develop a piston ring that has enough wear resistance to withstand use when applied, has good workability, and has excellent heat resistance and toughness.

C. Purpose of the Invention The present invention has been made in view of the above, and it is an object of the present invention to provide a piston ring that has various characteristics required of a piston ring and has sufficient wear resistance without hard chromium plating. It is an object.

2. Structure of the invention, that is, the present invention consists of 0.70 to 1.10% by weight of carbon, 3.0 to 6.0% by weight of chromium, 4.0 to 6.0% of molybdenum, and 1.0 to 2% of vanadium. .5% by weight, 5.0 to 8.0% by weight tungsten, and the remainder substantially iron.

Carbon forms carbides with iron, chromium, molybdenum, vanadium, and tungsten and contributes to wear resistance. If this is less than 0.70% by weight (hereinafter, weight% is simply expressed as "%"), the amount of carbide formed is so small that the above effect is insufficient, and if it exceeds 1.10%, the toughness decreases. Therefore, the range is set to 0.70 to 1.10%.

Therefore, it is set in the range of 3.0 to 6.0%.

Molybdenum forms carbides and contributes to wear resistance. If this is less than 4.0%, the above effect is insufficient, and 6.0%.
Since the effect is not significantly increased even if the content exceeds 4.0% to 6.0%.

Vanadium and tungsten together form carbides to improve wear resistance and also provide resistance to temper softening. If vanadium is less than 1.0%, the above effects are insufficient, and if it exceeds 2.5%, toughness is impaired, so the range is set to 1.0 to 2.5%.

If the tungsten content is less than 5.0%, the above effects are insufficient, and if it exceeds 8.0%, the toughness is impaired, so the range is set to 5.0 to 8.0%.

E, Example Next, a specific example of the present invention will be described.

0゜84%C13, 92%Cr, 4.97%MO21
, 88% V, and 6.20% W, the balance being substantially iron, was used as a sample with a hardness of HMV 500 to 800 under the heat treatment conditions shown in the table.

Steel for valve springs SWO treated with oil as a comparative material
The following tests were conducted on sc-v using hard chromium-plated cast iron as a comparison material.

(1) The main parts of the wear test test device are schematically shown in Fig. 1. Lubricating oil is passed from the back side into the center of a disc 2 with a diameter of 80 m that is removably attached to the stator holder 1. is lubricated. A pressing force is applied to the stator holder 1 toward the right in the figure by a hydraulic device (not shown) at a predetermined pressure. A rotor 4 is disposed opposite to the disk 2, and is rotated at a predetermined speed by a drive device (not shown). A test piece holder 5 removably attached to the rotor 4 has four test pieces 6 of 5n square and 10 squares in height spaced concentrically at equal intervals. In such a device, a predetermined pressing force is applied to the stator holder 1 so that the disc (mating material) 2 and the test piece 6 come into contact with each other with a predetermined surface pressure, and the test piece 6 is slid from the oiling hole 3. The rotor 4 is rotated while lubricating the surface at a predetermined lubricating speed. A test was conducted using such a testing device, and after the test, the test piece 6 was removed and brought into contact with 2 due to wear.

The test conditions are as follows. Mating disc material: Cast iron FC25 for Nijilinda liner, friction speed: 3m/sec
, 5s/see, Lubricating oil and oil supply conditions: Oil mixed with a considerable amount of sludge used in a 50-hour durability test of a diesel engine, oil temperature 80℃, 350-400℃
c/min, contact pressure: 100kg/aJ, friction distance: 100ka+.

The test results are shown in Figure 3. As can be seen from the figure, the material of the piston ring based on the present invention is similar to that of the comparative swo.
Compared to sc-v, it has less wear on the road and shows wear resistance equivalent to a chrome plating layer, which has traditionally been said to have excellent wear resistance. Shows better wear resistance than plated layers.

(2) Scuff test The test was conducted in the following manner using the test equipment used in the abrasion test. That is, as in the abrasion test described above, the test piece 6 is slid on the disk 2, and the pressure acting on the stator holder 1 is increased in a stepwise manner at regular intervals. Torque (frictional force) T generated on the stator holder 1 due to friction between the stator holder 1 and the load cell 8 is applied to the load cell 8 via the spindle 7 shown in FIG. 2, which is a side view taken along line nn in FIG. , read the change with dynamic strain meter 9,
Record it on the recorder 10. It is assumed that scuffing occurs when the torque T suddenly increases, and the contact surface pressure at that time is used as the scuffing surface pressure, and the quality of the scuffing resistance is judged based on the magnitude of the scuffing surface pressure.

The test conditions are as follows. Friction speed = 811 /
see, Lubricating oil: Motor oil #30, Contact surface pressure: 4
The weight was increased by 10 kg/aj every 3 minutes from 0 kg/aj, and the other conditions were the same as in the above wear test.

The test results are shown in Figure 4. Test piece fish 4 is 10
5kg/c+J is shown, which means that the contact surface pressure is 10
This shows that scuffing occurred during the process of increasing the weight from 0 kg/ad to 110 kg/aJ. As can be seen from the figure,
The material of the piston ring according to the invention is comparatively swosc.
-V has a higher scuff-generating surface pressure, is equal to or higher than that of a hard chromium plating layer, and has excellent scuff resistance.

(3) Tension reduction test? 6. OmX 1.2+n+mX 3.1+wm plain pressure ring JIS B 8032r
The tension reduction test specified in "Piston Ring" was conducted. The heating temperature was 300°C as specified, but the heating time was 5 hours and 10 hours in addition to the standard 1 hour.

The test results are shown in FIG. From the figure, it can be seen that, compared to the comparative 5WO3C-V, the piston rings based on the present invention have an extremely low degree of tension loss (and excellent heat resistance (JIS standard: 300°C for 1 hour). 10% or less when heated).

As described in detail, the piston ring according to the present invention has the above-described structure, and thus has extremely excellent wear resistance equivalent to or better than that of a piston ring plated with hard chrome. In particular, by setting the hardness to HMV 700 or higher, it shows even better wear resistance and scuff resistance. Therefore, there is no need to perform hard chromium plating, and manufacturing costs can be kept low.

Moreover, they all have excellent heat resistance, extremely low tension loss, and significantly improved durability. Therefore, when the piston ring according to the present invention is used, the so-called open period from one overhaul of the internal combustion engine to the next overhaul is significantly extended, which has great industrial utility value.

Fii of the drawing! All explanatory drawings show examples of the present invention. Figure 1 is a partial sectional view showing the main parts of the test equipment used in the wear test and scuff test, and Figure 2 is a cross-sectional view of the main part of the test equipment used in the wear test and scuff test. 3 is a graph showing the results of the abrasion test, FIG. 4 is a graph showing the results of the scuff test, and FIG. 5 is a graph showing the results of the tension reduction test.

In addition, in the symbols shown in the drawings, 1...Stator holder 2...Disc (mating material) ３・・・・・・・・・Lubrication hole 4・・・・・・・・・Rotor 5......Test piece holder 6......Test piece 7・・・・・・・・・Spindle 8・・・・・・・・・Load cell 9・・・・・・Dynamic strain meter It is.

Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 1M2 hours, hr

Claims (1)

[Claims] 1 Carbon 0.70-1.10% by weight, chromium 3.0-6
．． 0% by weight, molybdenum 4.0-6.0% by weight, vanadium 1.0-2.5% by weight, tungsten 5.0-8.
A piston ring consisting of 0% by weight and the remainder being substantially iron.