JP2007278403A - Oil ring wire rod manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a small-section two-piece-type oil ring wire rod for reducing man-hours with no performance deterioration of an oil ring. <P>SOLUTION: The method of manufacturing the two-piece-type oil ring wire rod with its approximately H-shaped cross section having a circumscribed circle diameter of 10 mm or smaller, which has a plurality of through-holes in the longitudinal direction of the wire rod, comprises a perforating step of laser-perforating the predetermined-size through-holes in the face of the oil ring wire rod corresponding to the outer peripheral face of the oil ring, and then a step of giving blasting treatment to the face of the oil ring wire rod corresponding to the inner peripheral face of the oil ring to form a blasting-treatment face with its surface roughness of maximum height Rz=10 μm or lower. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method of manufacturing an oil ring wire having a plurality of through holes in the longitudinal direction of the wire.

In manufacturing an oil ring wire having a plurality of through holes of a predetermined size used in a two-piece type oil ring in the longitudinal direction of the wire, a laser drilling method has been proposed as a method of forming the through hole.
This two-piece type oil ring is composed of a ring formed by bending an oil ring wire having a substantially H-shaped cross section into a C-shape and one coil expander. With this structure, the outer periphery of the ring is pressed against the inner wall of the cylinder with an appropriate pressure.

For example, Patent Document 1 improves the characteristic that shape defects such as cracks and burrs of the two-piece type oil ring do not occur by forming a through hole communicating with the radial direction of the two-piece type oil ring by laser beam processing. Proposals have been made.
In patent document 1, it consists of two, the case where a hole is formed in the state of a wire before ring forming, and the case where a hole is formed after ring forming. In any case, since no punching is used, the ring is free from cracks and burrs.
Patent Document 2 discloses that heating is performed using a high thermal energy density heating method including a YAG laser, and oxygen or air is used as an assist gas.
Further, as disclosed in Patent Document 3, due to the recent demand for lower fuel consumption, the two-piece type oil ring is required to have a low friction between the oil ring and the inner wall surface of the cylinder when incorporated in the engine. Patent Document 3 proposes an oil ring having wear resistance, heat resistance, and corrosion resistance by applying a surface treatment that forms a coating on the outer peripheral surface that slides with the cylinder inner wall surface of the oil ring.
JP-A-3-260473 Japanese Patent Laid-Open No. 9-159025 JP 2004-197818 A

Although the method for manufacturing a two-piece type oil ring disclosed in Patent Document 1 or 2 described above is advantageous in terms of reducing the man-hours for drilling, the through hole is drilled by laser processing on the surface of the oil ring wire. There is a problem that solidified residue (dross) generated around the through hole on the laser emission side adheres. If dross remains, there is a risk that a lump of metal may be mixed in engine lubricating oil and damage to the cylinder wall surface during use of the engine due to dropping of the dross.
Further, if foreign matter such as dross exists on the inner peripheral surface of the oil ring, the movement of the coil expander combined with the oil ring may be hindered, and the performance of the engine may be deteriorated.
In the manufacturing method disclosed in Patent Document 2, it is also disclosed that dross generated at the time of drilling a through hole is reheated and melted from the emission side and blown away. For other dross countermeasures, the effectiveness of the in-line dross removal method by rubbing (grinding, cutting, chipping) is described. However, these methods require highly accurate tool adjustment.
In addition, in order to perform surface treatment on the outer peripheral surface of the oil ring for reducing friction, which is disclosed in Patent Document 3, the surface of the outer peripheral surface of the oil ring serving as a base layer of the surface-treated surface is made smooth. There is a need to.

  In view of the above-described problems, an object of the present invention is a method for manufacturing a two-piece oil ring wire having a small cross section, which is capable of reducing the number of man-hours without deteriorating the performance as an oil ring. It is to provide a manufacturing method.

  The inventor has found that the present invention adopts a process of laser drilling from a surface corresponding to the outer peripheral surface of the oil ring of the oil ring wire and a predetermined blasting process to the surface corresponding to the inner peripheral surface. did.

  That is, the present invention is a method of manufacturing a two-piece type oil ring wire having a cross section having a plurality of through holes in the longitudinal direction of the wire and having a circumscribed circle diameter of 10 mm or less and a substantially H-shaped cross section. A drilling step of drilling a through-hole of a predetermined dimension by a laser from a surface corresponding to the outer peripheral surface of the oil ring of the wire, and then blasting the surface corresponding to the inner peripheral surface of the oil ring of the oil ring wire It is a manufacturing method of the wire material for oil rings which has the process of forming the blast processing surface whose roughness is the maximum height Rz = 10 micrometers or less.

  According to the present invention, it is an important technique indispensable for improving the quality and productivity of oil ring wires having a small cross section such as a two-piece oil ring having a substantially H-shaped cross section.

The important features of the present invention will be described specifically.
First, a drilling step is provided in which a through hole having a predetermined size is drilled by a laser from a surface corresponding to the outer peripheral surface of the oil ring of the oil ring wire. The reason for drilling through holes from the surface corresponding to the outer peripheral surface of the oil ring of the oil ring wire is that the surface corresponding to the outer peripheral surface of the oil ring slides up and down the cylinder inner wall in the two-piece type oil ring Thus, it has a role of a flow path for scraping off excess lubricating oil on the inner wall of the cylinder and discharging it from the through hole, and a smooth surface is required to reduce friction. According to the present invention, there is no occurrence of dross on the surface corresponding to the outer peripheral surface of the oil ring wire by drilling a through hole of a predetermined size with a laser from the surface corresponding to the outer peripheral surface of the oil ring wire. Thus, the risk of damaging the cylinder inner wall due to dross dropping is reduced. In addition, a smooth surface can provide an optimum surface as a surface to be surface-treated.
Since ordinary oil ring wires are manufactured by extrusion or rolling, the surface corresponding to the outer peripheral surface of the oil ring can be used in the surface state after processing, and the optimal surface for surface treatment can be obtained. You can also.
The surface roughness of the rail portion formed on the outer peripheral surface of the oil ring is preferably 5 μm or less, more preferably 1 μm or less, in terms of the maximum height Rz.

Next, a step of performing a blasting process on a surface corresponding to the inner peripheral surface of the oil ring of the oil ring wire is provided. Since the coil expander is inserted into the inner peripheral surface of the oil ring, the surface corresponding to the inner peripheral surface of the oil ring of the oil ring wire is not hindered to prevent sliding between the coil expander and the inner peripheral surface of the oil ring. Need to be smooth. For this reason, dross generated on the surface corresponding to the inner peripheral surface of the oil ring is removed by blasting.
According to the present invention, dross can be completely removed by performing blasting. In the blasting process, it is necessary to smooth the surface corresponding to the inner peripheral surface of the oil ring of the oil ring wire to a level that minimizes the influence of the inner peripheral surface of the oil ring.
The blasting treatment is also effective for removing spatter that is generated and adhered when a through hole is formed in the oil ring wire with a laser.
Zirconia, alumina particles, and steel balls can be used as the grains used for the blast treatment. Moreover, it is also possible to mix and use these.

  In the present invention, the blasted surface is formed on the surface corresponding to the inner peripheral surface of the oil ring. The surface roughness of the blasted surface needs to be Rz = 10 μm or less at the maximum height. When the surface roughness of the surface corresponding to the inner peripheral surface of the oil ring exceeds Rz = 10 μm, the coil expander cannot be reliably brought into contact with the inner peripheral surface of the oil ring, and the coil extract combined with the oil ring It may interfere with the movement of the panda and degrade the engine performance. Preferably, a blasted surface with Rz = 5 μm or less is formed.

In the present invention, the cross-section with a circumscribed circle diameter of 10 mm or less is limited to a wire having a substantially H-shaped cross section. It is because it cannot be maintained.
The oil ring reciprocates on the cylinder inner wall surface to form an appropriate amount of lubricating oil film on the cylinder inner wall surface. That is, when the piston approaches the combustion part, the lower rail part scrapes off the lubricating oil on the inner wall surface and discharges it from the through hole of the web part. Conversely, when the piston moves away from the combustion part, excess lubricant is scraped off by the upper and lower rail parts. Therefore, the part which connects two rail parts is required, and a cross-sectional shape takes substantially H shape.

When the oil ring wire of the present invention is applied to an oil ring, for example, the shape shown in FIGS. At this time, as typical dimensions, the thickness 1 of the web portion is 0.7 mm or less, the width 2 of the through hole formed in the web portion is 0.1 to 1.2 mm, and the length 3 of the through hole is 0.1. ˜5.0 mm, and the pitch 4 of the through holes is 1 to 10 mm.
The dimension 5 between the insides of the two rails is reduced to 2 mm or less in order to reduce the amount of lubricant scraped off. The dimension in the width direction of the through hole is also narrowed to 1.2 mm or less, and further to 0.4 mm or less.

In the present invention, it is preferable to provide an oil application step of applying oil to the surface on which the through hole of the oil ring wire is formed. Oil application has the effect of drastically reducing spatter. The effect is considered to be due to the prevention of the occurrence of welding by suppressing the direct contact between the metal surface and the droplet when the scattered metal droplet lands on the metal surface.
In the present invention, it is preferable to provide a preliminary drilling step for drilling a small-diameter hole. Since the drilling step has a small diameter, it is not necessary to introduce high energy, which is effective in suppressing sputtering.
Next, it is preferable to provide a finishing drilling step for forming holes of a predetermined size. As a result, the holes formed in the pre-drilling step are expanded, so that the sputtered portion limited to the vicinity of the through-hole, that is, the substantial expanded portion is processed and removed by the effect of oil application.

  The workpiece has the dimensions shown in FIG. 1, and the material used is a rolled material equivalent to SUS440B defined by JIS G4303. As processing conditions, a YAG pulse laser with an output of 6 kW was used as the laser used. A through hole having a predetermined dimension was drilled by a laser from a surface corresponding to the outer peripheral surface of the oil ring of the oil ring wire. The oil was applied to the perforated surface of the oil ring wire by brushing. As the oil, cold rolling oil (viscosity 20 cSt / 40 ° C.) was used. The size of the hole drilled in the oil ring wire is 0.5 mm for the through hole width, 1.0 mm for the through hole length 3, 10 mm for the through hole pitch 4, 0.5 mm for the web thickness 1, and between the rails. The inside dimension 5 was 1.7 mm, the circumscribed circle diameter was 3.65 mm, the preliminary drilling beam diameter was φ0.3 mm, and the final drilling beam diameter was 0.6 mm. Pre-drilling and finish drilling were carried out in separate passes. The feeding speed of the wire was sent at 12 m / min.

Next, the surface corresponding to the inner peripheral surface of the oil ring of the oil ring wire was subjected to blasting. The nozzle diameter for blast discharge was φ8.3 mm, and the distance between the nozzle tip and the workpiece (standoff amount) was 35 mm. The particles used for the blast treatment were zirconia, and the treatment was performed at a discharge pressure of 0.3 MPa.
After drilling with a laser, blasting was performed, and adhesion of dross was confirmed with a scanning electron microscope.

An example of the embodiment of the present invention is shown in FIG. From FIG. 3, it was confirmed that dross likely to fall off was completely removed around the through hole formed over the entire length of the surface corresponding to the inner peripheral surface of the oil ring of the oil ring wire.
When the surface roughness of the rail portion of the surface corresponding to the outer peripheral surface of the oil ring wire was measured, it was Rz = 0.9 μm.
Further, when the surface roughness of the surface corresponding to the inner peripheral surface of the oil ring of the oil ring wire was measured, Rz = 4 μm.
Thus, in the present Example, the optimal wire rod as an oil ring wire rod was able to be obtained.

It is a block diagram which shows an example of this invention. It is a top view which shows the through-hole part of FIG. It is a scanning electron micrograph which shows an example of this invention.

Explanation of symbols

1. Web thickness, 2. 2. the width of the through hole; 3. the length of the through hole; 4. Pitch of through holes, Inner dimensions between rails, 6. Rail part, 7. Through hole

Claims (1)

A method of manufacturing a two-piece type oil ring wire having a substantially H-shaped cross-section with a circumscribed circle diameter of 10 mm or less having a plurality of through holes in the longitudinal direction of the wire, A drilling step of drilling a through-hole of a predetermined dimension from a surface corresponding to the outer peripheral surface, and then blasting the surface corresponding to the inner peripheral surface of the oil ring of the oil ring wire, the surface roughness is maximized The manufacturing method of the wire material for oil rings characterized by including the process of forming the blasting surface of thickness Rz = 10 micrometers or less.