JPH0673518A - Production of wire rod for piston ring - Google Patents

Abstract

PURPOSE:To provide a wire rod for piston ring made of titanium alloy, capable of working into a piston ring excellent in shape and dimensional accuracy by means of cold coiling. CONSTITUTION:Annealing and cold working are repeatedly applied to a wire rod composed of alpha plus beta titanium alloy to work it into a square-shaped or flat-shaped wire of special form. Then, this wire of special shape is subjected, while being held in a practically linear state, to heating up to 840-970 deg.C, to rapid cooling, and to heating up to 450-680 deg.C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piston ring wire used for a pressure ring, an oil ring, etc. of an internal combustion engine.

[0002]

2. Description of the Related Art A piston ring in an internal combustion engine such as an automobile engine is a pressure ring for maintaining the airtightness of a combustion chamber and an oil ring for adjusting a lubricating oil film between cylinder walls. It is an important component that greatly affects the performance.

A conventional piston ring is mainly made of a wire material made of spring steel having heat resistance and wear resistance. After being processed into a ring shape by coiling, it is hard on the outer peripheral surface that slides on the cylinder wall. It was plated with chrome to improve wear resistance.

[0004] In recent years, as the performance of automobile engines has increased, such as high output and high rotation, piston rings are required to have further improved heat resistance and wear resistance, as well as corrosion resistance and weight reduction. As a countermeasure, a piston ring made of 13Cr and 17Cr martensite stainless steel whose surface is nitrided is used,
The piston ring is being thinned.

However, even if the above-mentioned stainless steel is used, its heat resistance and corrosion resistance in a high temperature corrosive atmosphere are still insufficient, and there is a limit in strength even in weight reduction by thinning. At present, there is a demand for a material having excellent characteristics.

[0006]

The material of the piston ring is, of course, not only excellent in the above-mentioned various characteristics, but also required to be excellent in bending workability and accurately in a ring shape. It is required that the wire be in the form of a wire that can be processed into.

[0007] Because, the processing method of the piston ring is
Generally, the wire is processed into a ring shape by a coiling method similar to spring winding that can be processed at low cost, so the wire has excellent straightness, no twisting, no hardness unevenness, and bending in cold. It is essential to have a suitable hardness and toughness that are easy to process.

Therefore, in recent years, it has been attempted to use an α + β type titanium alloy as a material for the piston ring, and an α + β type titanium alloy is used which makes use of the excellent corrosion resistance, heat resistance and low specific gravity of the α + β type titanium alloy. Commercialization of piston rings is in progress. However, in order to commercialize the piston ring made of α + β type titanium alloy, first of all, it is premised that the wire for piston ring made of α + β type titanium alloy that can be coiled with high precision is manufactured.
Development of a β-titanium alloy piston ring wire is required.

The present invention has been made in view of the above points, and provides a wire rod for a titanium alloy piston ring, which can be processed into a piston ring excellent in shape and dimensional accuracy by cold coiling. With the goal.

[0010]

In order to achieve the above object, a method for manufacturing a titanium alloy wire for a piston ring according to the present invention is described in Ti-6A1-4V and Ti-8A1-1.
Α + β such as Mo-1V, Ti-5A1-2Cr-1Fe
A wire made of a titanium alloy is repeatedly annealed and cold-worked to be processed into a rectangular or flat shaped deformed wire, and the deformed wire is continuously maintained in a substantially straight state, and is maintained at 840 to 970.
After heating to ℃, it is quenched and then heated to 450 to 680 ℃.

The reasons for limiting the various numerical values are as follows. By heating the wire rod to 840 to 970 ° C. and then rapidly cooling it, the wire rod is heated to 840 to 970 ° C. to soften the wire rod and straighten the bending and twisting generated by the deforming process in the previous step. Then, by rapidly cooling in the straight state, the straight state can be maintained at room temperature. Furthermore, martensite is generated by rapid cooling from a high temperature below the β transformation point, and the hardness is HV suitable for coiling.
It can be 320-390.

If the heating temperature exceeds 970 ° C., the hardness increases and the yield strength becomes high, so that a large force is required for coiling, and randomization of the structure begins to occur, and a non-uniform structure is apt to occur. It becomes difficult to perform coiling with high dimensional accuracy. On the other hand, when the heating temperature is lower than 840 ° C, the wire material is insufficiently softened and cannot be straightened.

Heating to 450 to 680 ° C. after quenching removes the internal strain generated by quenching and prevents the occurrence of bending due to aging. Then, heating above 680 ° C. causes a decrease in hardness. On the other hand, if the temperature is lower than 450 ° C, the internal strain is insufficiently removed.

[0014]

EXAMPLES Examples of the present invention will be described below. Ti-6A1-4V α + β titanium alloy wire rods with chemical composition of A1: 6.2% by weight, V: 3.9% by weight, and the balance being substantially Ti, are thinned by repeating annealing and wire drawing. After being made into a shape, roller rolling was performed to form a deformed wire rod 1 having a thickness of 1.05 mm and a width of 2.4 mm.

Then, the wire 1 was subjected to the final heat treatment by the heat treatment apparatus 2 as shown in FIG. In the heat treatment device 2, the cooling device 4 was provided at the rear part of the first heating device 3, and the second heating device 5 was further provided at the rear part of the cooling device 4. Then, the wire rod 1 is continuously supplied from the feeding device 6,
The heating device 3, the cooling device 4, and the second heating device 5 are passed in this order,
Finally, it is continuously wound up by the winding device 7. The above-mentioned series of devices are linearly arranged so that the wire rod 1 moves linearly. The cooling device 4 was cooled by oil.

Next, the wire 1 was heat-treated by using the above-mentioned heat treatment apparatus at the heating temperature and holding time shown in Table 1.
The coiling workability was evaluated by performing a coiling process test using the finished piston ring wire. Test No. A and B are examples of the present invention, and test N
o. C, D and E are comparative examples. The test No. C, D
Is a wire which has been subjected to the final heat treatment and has been coiled. E is a wire rod that has just been rolled and is directly coiled.

[0017]

[Table 1]

Hardness and elongation are mechanical properties of the piston ring wire before coiling, and hardness of HV320 to 390 and elongation of 6% or more are preferable for improving coiling workability. .

In the coiling test, a piston ring wire 9 was continuously bent by a three-point roller 8 as shown in FIG. 2 to obtain a slinky 10 having an outer diameter of 80 mm. Then, the slinky 10 is cut and processed into a C-shaped ring 11 as shown in FIG. 3, and whether or not the ring outer diameter A shown in FIG. Then, the presence or absence of fluctuations in the deflection C in which the ring 11 shown in FIG. As a result, the test No. In Nos. A and B, there were no fluctuations in the ring outer diameter, fluctuations in the rising edge, and fluctuations in deflection, and the test No. It can be seen that compared to C, D, and E, ring processing can be continuously performed in a constant shape, coiling workability is excellent, and ring processing can be performed with high accuracy.

Generally, the variation of the ring outer diameter occurs when the wire material has unevenness in hardness or bending. Further, the fluctuation of the rising edge and the fluctuation of the twisting occur when the wire rod is bent or twisted.

Then, the test No. which is an embodiment of the present invention.
From the wire used for A, a piston ring whose surface is actually nitrided is made, and heat resistance, corrosion resistance in high temperature atmosphere,
When the wear resistance and weight reduction were investigated, good results were obtained.

[0022]

EFFECTS OF THE INVENTION Since the present invention has the above-mentioned structure, the piston ring made of titanium alloy can be easily processed from the wire by coiling, and the shape of the piston ring can be stabilized and the size and shape can be processed with high accuracy. Thus, excellent effects such as a large contribution to the practical use of the titanium alloy piston ring are achieved.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an example of an apparatus for carrying out the present invention.

FIG. 2 is a schematic view showing a coiling method of a piston ring.

3A and 3B are schematic diagrams showing the shape of a piston ring.

[Explanation of symbols]

 1 wire rod 2 heat treatment device 3 1st heating device 4 cooling device 5 2nd heating device 6 feeding device 7 winding device 8 three-point roller 9 piston rod wire rod 10 slinky 11 ring 12 cutout A outer diameter B rise C

Claims (1)

[Claims] 1. A wire made of an α + β type titanium alloy is repeatedly annealed and cold-worked to be processed into a rectangular or flat-shaped deformed wire, and the deformed wire is continuously maintained in a substantially linear state, and 840 to 970. After heating to ℃, quenching, then 4
A method for manufacturing a piston rod wire, comprising heating to 50 to 680 ° C.