JP2003287130A - Method of manufacturing side rail of combined oil ring - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve such a problem with a side rail of a combined oil ring that the side rail of the combined oil ring subjected to nitriding on the outer peripheral surface thereof causes a large deformation on a disk, and a specified outside diameter dimension cannot be provided. <P>SOLUTION: The material of the side rail is formed by coiling beforehand to manufacture a coil 1. The coil is expandedly brought into contact with the inner peripheral surface of a fixture 6 having a specified dimension on the inner peripheral surface thereof. The fixture 6 is loosened, and the coil 1 is re-tightened. In this state, nitriding is applied to the coil, and the coil 1 is cut off in axial direction to provide the side rail. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a side rail of a combined oil ring used in an internal combustion engine, and more particularly to a method of manufacturing a side rail of a combined oil ring in which the outer periphery is subjected to ion nitriding or radical nitriding.

[0002]

2. Description of the Related Art In recent years, steel combination oil rings have been frequently used as the load of internal combustion engines has increased. This combined oil ring is composed of a spacer expander and two side rails, and in order to adapt to a high load, nitriding treatment has also been performed on the outer peripheral surfaces of the side rails. Along with this, an abnormal wear phenomenon of the oil ring groove of the aluminum alloy piston has started to occur in some engines using unleaded gasoline.

This is because the hardness of the nitride layers formed on the upper and lower surfaces of the side rail is too high as compared with aluminum. Further, the nitride layers formed on the upper and lower surfaces are not preferable from the viewpoint of breakability of the thin side rails, while the side rails have a strong tendency to be thin. For these reasons, it is desired to form the nitride layers only on the outer peripheral surface of the side rail without forming the nitride layers on the upper and lower surfaces thereof.

Conventional nitriding is performed by gas nitriding. With the gas nitriding treatment, the entire surface of the side rail is nitrided. Therefore, in order to obtain a side rail in which a nitride layer is formed only on the outer peripheral surface of the side rail,
After the gas nitriding treatment, the nitrided layers on the upper and lower surfaces and the inner peripheral surface must be removed by machining or nitriding prevention treatment must be performed.
However, these have great disadvantages in terms of cost.

As measures for solving the above-mentioned problems in terms of function and cost, (1) Japanese Patent Laid-Open No. 8-296
496, an ion nitriding treatment capable of forming a nitride layer only on the outer peripheral surface by the material setting method,
(2) Japanese Patent Application Laid-Open No. 7-18826 and Japanese Patent Application Laid-Open No. 8-3
The use of a special nitriding treatment (hereinafter referred to as radical nitriding treatment) described in Japanese Patent No. 5053 is cited.
The processing methods disclosed in both publications have various processing conditions such as different equipment specifications and different kinds of gas to be used, but have a common feature that a nitride layer is formed only in a portion where glow discharge occurs. All of them (both ion nitriding and radical nitriding) are processing methods capable of forming a nitride layer only on the outer peripheral surface of the side rail.

A method of manufacturing a side rail in which a nitrided layer is formed only on the outer peripheral surface by utilizing ion nitriding treatment is disclosed in Japanese Patent Laid-Open No. 8-2
The one described in Japanese Patent No. 96496 is known. The feature of the manufacturing method disclosed in this publication is that the outer diameter dimension (X ′) of the cylindrical body 2 is made to match the inner circumference of the coil as the side rail material before nitriding treatment as shown in FIG. With the coil 1 (see FIG. 1) as the side rail material attached to the outer peripheral surface of the cylindrical jig 2 (hereinafter referred to as the inner peripheral reference jig), the ion nitriding treatment is performed with only the outer peripheral surface of the coil exposed. By doing so, the nitride layer is formed only on the outer peripheral surface of the side rail (see FIG. 4).

In FIG. 4, the coil 1 is inserted so that the inner peripheral surface of the coil 1 is in contact with the outer peripheral surface of the hollow cylindrical jig 2, and the lower surface of the coil 1 is brought into contact with the lower step of the jig 2. Moreover, the upper surface is brought into contact with the plate 3a, and the plate 3a and the plate 3b in contact with the lower surface of the jig 2 are tightened using the rod 4 and the nut. Nitriding is performed in the state shown in FIG. 4, the coil 1 is taken out from the jig 2, and the coil 1 is cut in the vertical direction to obtain a plurality of side rails with abutment.

It is technically possible to form a nitride layer only on the outer peripheral surface of the side rail by applying a manufacturing method similar to this to radical nitriding, since it is a similar processing method. According to this treatment, there is an advantage that a compound layer (which is extremely brittle and is a fatal defect for a sliding component requiring high slidability and requires post-processing such as polishing) is not formed depending on the treatment conditions. The radical nitriding treatment is known, and is performed by precisely controlling the glow discharge of a mixed gas of ammonia and hydrogen, and it is highly active if a plasma having a low ion density and a low energy state is selectively generated. Radical (active species)
Under the condition that the compound layer is not effectively deposited and the compound layer is not deposited,
Nitriding treatment can be performed.

[0009]

However, the above
In a method of manufacturing a side rail using an inner circumference reference jig (see FIG. 3) of a coil similar to the means disclosed in JP-A-8-296496, a plate is used when ion nitriding or radical nitriding treatment is performed. There is a problem that the defective rate of deformation becomes high. When the ion-nitrided and radical-nitrided products were evaluated, it was found that the radical-nitrided product tended to have a larger dish deformation amount than the ion-nitrided product (Comparative Example 1 in FIG. 12 (ion-nitriding), comparison. See Example 2 (radical nitriding).

The dish deformation referred to here is as shown in FIG.
Piston ring (including side rail) 12 on surface plate 13
When either side of the ring is left stationary and the ring 12 is viewed from a horizontal position with respect to the surface plate surface 13, it is a deformation of the ring 12 that looks like a dish plate, and product quality peculiar to the piston ring 12 is poor. Is. Usually ring 12
It is desirable that the side surface is parallel to the surface plate surface 13. Also,
As an evaluation method of dish deformation, the height from the surface plate 13 to the side of one side of the abutment was measured on both the front and back sides with the opposite side of the ring abutment after cutting pressed (see Fig. 6), and the dish deformation was made with the difference. There is a method of setting the amount (unit: mm), and this time, this method was used for evaluation.

Regarding the side rails, the following problems are given to the quality and performance of the dish deformation. (1) Assembling to the piston deteriorates. (2) When the dish deformation is extremely large, it adversely affects oil consumption. For the above reason, suppressing dish deformation is an important issue for the combined oil ring.

By the way, in the method of manufacturing the side rail in which the nitride layer is formed only on the outer periphery using ion nitriding or radical nitriding, only the portion where the glow discharge is generated is nitrided, as described above. There is no problem if it is set on the jig with only the outer peripheral surface of the coil exposed. However, if the nitriding process is performed in a state where there is a gap between the adjacent surfaces in the axial direction when the coil is set in the jig, a nitride layer is naturally formed also in the gap (see FIG. 8). The distribution of the nitriding layer on the outer peripheral surface becomes non-uniform, and the portion containing a large amount of nitriding expands and expands, so that dish deformation is induced.

Radical nitriding treatment is disclosed in Japanese Patent Laid-Open No. 8-3505.
As disclosed in Japanese Patent Publication No. 3, it has a feature that a uniform nitride layer can be obtained on the entire surface even in a material surface state having a complicated uneven shape, as compared with a general ion nitriding treatment. That is, in other words, with regard to the manufacture of the side rails, there is a feature that the nitride layer easily penetrates between the adjacent surfaces in the axial direction of the coil.

Therefore, the distribution of the nitrided layer obtained by the radical nitriding treatment has a higher sensitivity (sensitivity) with respect to the setting accuracy such as a gap generated at the time of setting the coil than the ion nitriding treatment. The level of dish deformation is larger in the radical nitriding product than in the ion nitriding product due to the difference in sensitivity.

In the manufacturing method using the inner circumference reference jig as in Japanese Unexamined Patent Publication No. 8-296496, as shown in FIG. 4, the coil 1 is still attached to the outer circumference surface of the inner circumference reference jig 2. , The rod 4 by the upper and lower clamp discs (plates) 3a and 3b so that the adjacent faces of the coil 1 contact each other.
The coil 1 is tightened using the nuts 5 and 5, and the coil 1 is set on the jig so that only the outer peripheral surface of the coil is exposed. In this case, since the coil inner peripheral surface is in close contact with the outer peripheral surface of the inner peripheral reference jig 2, even if a tightening load is applied from above and below, the contact portion between the coil 1 and the inner peripheral reference jig 2 Since the frictional resistance of the coil 1 is large, a small gap remains between the adjacent surfaces of the coil 1, and the coil is set in the jig in a non-uniform manner.

From the above, in order to suppress dish deformation (see FIG. 5) in the manufacturing method in which the nitride layer is formed only on the outer periphery by utilizing the ion nitriding or radical nitriding treatment, the adjacent surfaces of the coil are closely packed. It is an important issue to improve the setting accuracy of the coil by making contact with the jig and to suppress the dish deformation.

On the other hand, when a nitride layer is formed only on the outer peripheral surface by ion nitriding or radical nitriding, the outer circumference of the coil extends more than the inner circumference, so that the curvature of the outer peripheral surface before and after the nitriding of the coil changes. That is, the outer dimensions of the coil after nitriding are reduced. It is important for the combined oil ring that the curvature of the outer surface of the side rail and the curvature of the inner surface of the cylinder are the same when in use.

An object of the present invention is to suppress dish deformation after nitriding in a method of manufacturing a side rail in which a nitrided layer is formed only on the outer peripheral surface by ion nitriding or radical nitriding.
It is to provide a manufacturing method capable of obtaining a desired outer diameter dimension.

[0019]

[Means for Solving the Problems] A step of coiling a wire rod made of a material for a side rail to form a coil, and a coil 6 is formed on the inner peripheral surface of a jig 6 whose inner peripheral surface has a prescribed size. The coil is set so that the outer peripheral surface spreads in the radial direction and contacts with each other, and both side surfaces of the coil are tightened; the coil is taken out in the expanded contacted state; It is characterized in that a step of performing a nitriding treatment or a radical nitriding treatment and cutting the nitriding-treated coil into a plurality of side rails.

Alternatively, in the method of manufacturing the side rail, after the jig 6 is slightly opened in the tightening step,
It is characterized by further including a step of tightening.

Further, the specified dimension of the inner circumference X of the jig 6 is calculated by the following formula, and the outer diameter dimension BB 'required after nitriding the coil and the outer diameter before and after the nitriding of the coil are calculated. A method for manufacturing a side rail of a combined oil ring, which has a total inner diameter dimension including a dimension difference. X = {BB '+ (AA'-BB')} = BB '+ C. Here, X: a reference dimension that is the outer diameter of the coil necessary for the setting state before nitriding, that is, the inner diameter dimension of the jig 6 (hollow cylinder) is shown. AA ': Indicates the outer diameter of the coil before nitriding. BB ': Indicates the outer diameter dimension required after nitriding. C: outside diameter dimension difference before and after nitriding of coil 1 (= AA '
-BB '). (Refer to FIGS. 1 and 2) When the nitride layer is formed only on the outer peripheral surface, the outer circumference extends as compared with the inner circumference, and the curvature of the coil changes before and after nitriding, so that the outer diameter of the coil after the nitriding treatment becomes small. Therefore, since the reference dimension X of the coil before nitriding is the side rail outer diameter dimension before final finishing (that is, the required outer diameter dimension BB ′) based on the outer dimension dimension after nitriding, the outer dimension dimension B after nitriding
It is the sum of B ′ and the external dimension difference C before and after nitriding.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is based on the requirement of axially tightened coils so that adjacent surfaces in the axial direction of an axially tightened coil are in intimate contact with each other, and ion nitriding or radical nitriding treatment. When both requirements are combined, glow discharge occurs only on the outer peripheral surface, and as a result, a nitride layer is formed only on the outer peripheral surface.

In the above-described method, the requirement that the coils are axially clamped so that the adjacent surfaces in the axial direction are in intimate contact with each other can prevent the penetration of the nitride layer into the adjacent contact surfaces of the coil. A side rail in which dish deformation is suppressed can be obtained.

When the coil is ion-nitrided only on the outer peripheral surface, the outer periphery of the coil extends more than the inner periphery, so that the curvature of the coil changes before and after nitriding, that is, the outer diameter of the coil becomes smaller after nitriding. . Therefore, the coil before nitriding can be obtained with a desired outer diameter by setting it in a jig so that the total outer diameter dimension required after nitriding and the outer diameter dimension difference before and after nitriding are set. Therefore, the inner diameter dimension X of the hollow cylindrical body of the jig 6 is set as described above.

An embodiment (using an outer peripheral reference jig) and a comparative example (using an inner peripheral reference jig) of the present invention will be described below with reference to the drawings. For comparison, for example, the required ring size is φ75 mm, the martensitic stainless steel strip plate wire rod dimensions are: axial width (h6 dimension) = 0.4 mm, radial thickness (Hereafter, a1
Dimension) = 2.02 mm. In addition, Table 1 and Table 2 show examples of manufacturing conditions listed below.

[0026]

[Table 1]

[0027]

[Table 2]

An embodiment of the present invention will be described. First, the coil 1 was produced from a strip wire rod made of martensitic stainless steel. At this time, the dish deformation is suppressed. This was packed in a jig 6 (outer peripheral reference jig) (see FIG. 9). Further, the outer peripheral surface of the coil 1 is fixed to the jig 6
The inner circumference of the hollow cylinder is expanded and contacted (the coil 1 is inserted into the jig 6 with a slightly reduced diameter and then released or is expanded in the direction of increasing the diameter) to be in close contact. Next, the clamp discs 10a and 10b are arranged at both ends of the coil 1, and the shaft portion 4 is inserted through the center holes of the clamp discs 10a and 10b.
The nut 5 is attached to the threaded portion of
It is screwed with [N ・ m] and clamped and fixed in the axial direction.
The inner diameter dimension X of the hollow cylinder is the outer diameter of the coil (see FIG. 10).
reference).

Here, the hollow cylindrical body of the jig 6 is accurately cut in the axial direction, and the mating portion 9 of the jig is the screw portion 8.
It has a structure where it is closed by tightening it and opened by loosening it. In addition, a part of the hollow cylinder is cut in the vertical direction, and the jig 7 is closed by the spacer 7 having a thickness corresponding to the thickness of the cutter in which the mouth 9 is formed. The inner diameter is X. By the way, the gap between the adjacent surfaces in the axial direction of the coil 1 varies depending on the region. Therefore, using the structure of the jig 6,
That is, the screw portion 8 is loosened, the abutment portion 9 is slightly opened, and the coil 1
By releasing the restraint force of the inner peripheral surface of the hollow cylinder of the jig 6 on the outer peripheral surface of the coil 6 and re-tightening with, for example, a tightening torque of 50 [N · m], the adjacent surfaces in the axial direction of the coil 1 are more closely packed. Then, the coil 1 was removed from the jig to obtain the work 11 (see FIG. 11).

When the nitride layer is formed only on the outer peripheral surface of the coil 1, the outer periphery of the coil 1 extends more than the inner periphery, so that the curvature of the coil 1 changes before and after nitriding.
The outer diameter of the coil 1 becomes smaller after nitriding. Therefore, when performing the ion nitriding treatment or the radical nitriding treatment only on the outer peripheral surface of the coil 1, it is necessary to consider the change of the coil diameter before and after the nitriding, and the inner diameter dimension X of the hollow cylindrical body of the jig 6 is as follows. Is formed as.

That is, the outer diameter of the coil before nitriding is A
A ', the outer diameter dimension required after nitriding coil 1 is B
B ', the outer diameter dimension difference before and after nitriding the coil 1 is C (=
When AA'-BB '), X = {BB' + (AA '
−BB ′)} = BB ′ + C (see FIG. 2). By the way, the ring size actually requested is, for example, φ75.
In the case of, the amount of change before and after nitriding was found to be 1.0 mm by the preliminary experiment, and the above-mentioned dimensions are AA ′ = φ76
mm, BB '= φ75 mm, C (= AA'-BB') = 1.
It is 0 mm, and the inner diameter X of the jig 6 is φ76 mm.

Next, the outer peripheral surface of the coil 1 was nitrided in an ion nitriding furnace and a radical nitriding furnace, respectively.
The conditions of the ion nitriding treatment are as follows, for example. Atmosphere gas composition: Nitrogen gas (N ₂ ): Hydrogen gas (H ₂ ) =
7: 3 Work temperature: 580 ° C. (without external heating: direct heating by glow discharge) Processing voltage: 630 V Radical nitriding conditions are, for example, as follows. Atmospheric gas composition: Ammonia (NH ₃ ): Hydrogen (H ₂ ) =
7: 3 Work temperature: 580 ° C (with external heating: Mainly heated by an external heater) Processing voltage: 500 V Under the above conditions, adjust the processing time so that the thickness of the nitride layer is the same. With the treatment, a nitride layer having a depth of 55 μm was obtained on the outer peripheral surface of the coil 1 at HV 700 or more.

After nitriding, the outer diameter of the coil 1 was reduced and the required outer diameter of φ75 mm was obtained. After that, the coil 1 was longitudinally cut into a side rail shape having an abutment portion, and a finished side rail was completed by a conventional method.

Next, a comparative example using the inner circumference reference jig 2 for confirming the effect of the present invention will be described. As the material before the nitriding treatment, the same material as the coil 1 manufactured with an outer diameter of φ76 mm with suppressed dish deformation was used.

Here, similarly to the present invention, the coil outer diameter dimension before nitriding is AA ', the outer diameter dimension required after nitriding the coil 1 is BB', and the outer diameter dimension difference before and after nitriding the coil 1 is C. (= AA′−BB ′), the outer diameter dimension of the coil 1 is AA ′ = B in consideration of the outer diameter dimension difference before and after nitriding.
B ′ + (AA′−BB ′) = BB ′ + C. As for the coil size before nitriding, the preliminary experiment shows that the difference in external dimension before and after nitriding does not change when the strip plate wire is used and the nitriding conditions are the same. It is the same regardless of whether it is a jig or a peripheral reference jig. However, in setting the dimensions of both jigs, the dimension of the inner circumference reference jig is based on the inner circumference of the coil, so it is the value obtained by subtracting twice the radial thickness of the wire from the outer circumference. Since the dimensions are based on the outer peripheral surface of the coil, they are the outer diameter of the manufactured coil itself. Therefore, when D is twice the radial thickness (a1 dimension) of the wire rod, the outer diameter dimension X'of the cylindrical body as the inner circumference reference jig is X '= AA'-2D.
From the viewpoint of the dimensional accuracy of the side rail outer circumference after nitriding, the outer circumference reference jig does not include the error (twice) in the radial thickness (a1 dimension) of the rail, so the inner circumference reference jig There is also an advantage that the accuracy is higher than that of the conventional method. As for the actual dimension setting, for example, the required ring size is φ75, the above dimensions are AA ′ = φ76 mm and BB ′ = φ75.
mm, C (= AA'-BB ') = 1.0 mm, D = (2a1)
= 4.04 mm, and as a result, the outer diameter dimension X ′ of the cylindrical body of the inner circumference reference jig is φ71.96 mm.

The coil was set on the jig as follows. First, the coil 1 is wound around the cylindrical body (see FIGS. 3 and 4) of the inner circumference reference jig 2. Clamp disk 3 at both ends
a, 3b are provided, and further clamp discs 3a and 3
The nut 5 is screwed onto the threaded portion of the shaft portion 4 which is inserted through the center hole of b, and is tightened and fixed in the axial direction (see FIG. 4). Since the tightening force is the same as that of the embodiment, the tightening torque = 50.
[N ・ m] After that, nitriding treatment is performed under the above-mentioned ion nitriding and radical nitriding treatment conditions, and the outer diameter dimension of the coil 1 after the nitriding treatment is reduced and the required outer diameter dimension φ7 is obtained.
After obtaining 5 mm, the coil 1 was cut into a side rail shape having an abutment portion, and a finishing side rail was completed by a conventional method.

FIG. 12 shows the amount of side rail dish deformation due to the difference between the coil setting method and the nitriding method. However, the comparative example shows the result of the product using the inner circumference reference jig, and the example shows the result of the product using the outer circumference reference jig (jig 6).
= Shows radical nitriding treatment. The coil material is martensitic stainless steel (17% Cr).

According to the result of FIG. 12, in the comparative example (using the inner peripheral reference jig), the dish deformation amount was large in both processing methods, but the radical nitriding processed product was larger.
On the other hand, in the examples of the present invention, although the radical nitriding treatment tends to be larger, both treatment methods are relatively smaller than the comparative examples, and a significant difference is not seen and dish deformation is suppressed. It was In the present invention, a greater effect of suppressing dish deformation was obtained especially in radical nitriding treatment.

[0039]

As described above, according to the present invention, dish deformation can be suppressed and desired in a method of manufacturing a side rail in which a nitrided layer is formed only on the outer peripheral surface by ion nitriding and radical nitriding. It is possible to obtain the outer diameter dimension of

[Brief description of drawings]

FIG. 1 is a perspective view of a material for a side rail wound into a spiral coil.

FIG. 2 is a plan view for explaining a diameter of a coil before and after nitriding.

FIG. 3 is a perspective view of a conventional inner circumference reference jig.

FIG. 4 is a perspective view showing a conventional example in which a coil is set on a jig.

FIG. 5 is a diagram for explaining the dish deformation of the side rails.

FIG. 6 is a perspective view showing measurement of a dish deformation amount.

FIG. 7 is a cross-sectional view showing a normal outer peripheral surface nitrided layer.

FIG. 8 is a cross-sectional view showing a state where a side surface of a rail is impregnated with a nitride layer.

FIG. 9 is a perspective view of a hollow cylindrical jig used in an example of the present invention.

10 is a cross-sectional view showing a state in which a coil is set on the jig shown in FIG.

FIG. 11 is a perspective view of the coil with the hollow cylindrical jig removed.

FIG. 12 is a graph showing a dish deformation amount of a side rail according to the method of the present invention and the conventional method.

[Explanation of symbols]

1 coil 2 Inner circumference reference jig 3a, 3b Clamp disc (for inner circumference reference jig) 4 shafts 5 nuts 6 jigs (perimeter reference jigs) 7 Spacer 8 screws 9 Abutment 10a, 10b Clamp disc (for outer circumference reference jig) 11 work

Claims (3)

[Claims] 1. A step of coiling a wire rod made of a material for a side rail to form a coil, and an outer peripheral surface of the coil is radially arranged on an inner peripheral surface of a jig whose inner peripheral surface has a predetermined size. Setting the coil so as to be in contact with each other so as to spread, and tightening both side surfaces of the coil,
A step of taking out the coil in the spread state, a step of subjecting the taken-out coil to an ion nitriding treatment or a radical nitriding treatment, and cutting the nitrided coil to form a plurality of side rails. , Manufacturing method of combined side rails. 2. The method of manufacturing a side rail of a combined oil ring according to claim 1, wherein the tightening step includes a step of further tightening after the jig is slightly opened. 3. The specified dimension of the inner circumference of the jig according to claim 1, as calculated by the following equation, is the outer diameter dimension required after nitriding the coil and the dimension before and after nitriding the coil. A method for manufacturing a side rail of a combined oil ring, which has a total inner diameter dimension including an outer diameter dimension difference. X = {BB '+ (AA'-BB')} = BB '+ C. Here, X: a reference dimension that is the outer diameter of the coil necessary for the setting state before nitriding, that is, the inner diameter dimension of the jig (hollow cylinder) is shown. AA ': Indicates the outer diameter of the coil before nitriding. BB ': Indicates the outer diameter dimension required after nitriding. C: outside diameter dimension difference before and after nitriding of coil 1 (= AA '
-BB ').