JP2006194095A - Oil groove machining method for cylinder bore - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an oil groove machining method for forming an oil groove in an arbitrary part on a surface of a bore simply while holding shape precision of the bore of a cylinder. <P>SOLUTION: This oil groove machining method comprises a process for machining the bore 10 up to rough dimension ψby leaving finish grinding allowance K by applying turning machining (boring machining) to the bore 10 of the cylinder 9, a process for forming a cut-in part 14 being deeper than the finish grinding allowance K on the surface of the bore 10 by applying turning machining to an oil groove forming part of the bore 10, and a process for grinding by only finish grinding allowance K by applying finish grinding (honing machining) on the whole surface of the bore 10 to form the oil groove 15 on the surface of the bore 10. When forming the cut-in part by turning machining, cut-in parts 14, 14 formed on the surface of the bore 10 by a turning tool 20 are not overlapped. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method of machining an oil groove in a cylinder bore of a cylinder block.

The cylinder block of the engine is provided with a plurality of cylinders for slidably inserting pistons. For example, as disclosed in Patent Document 1, the cylinder bore (here, the inner peripheral surface of the cylinder is a bore) is a process for reducing friction loss, reducing fuel consumption, and improving seizure resistance. Is given.
The cylinder bore requires wear resistance because the piston slides with the piston ring pressed. For this reason, the surface of the bore is subjected to processing for reducing friction loss by grinding (honing).
Further, an oil groove for retaining lubricating oil is formed on the surface of the bore of the cylinder, and processing for reducing fuel consumption by reducing oil consumption and improving seizure resistance is performed.

Plateo honing and laser honing are known as methods for machining an oil groove in a cylinder bore.
In plateau honing, for example, as shown in Patent Document 2, first, a deep groove is formed on the surface of the cylinder bore by grinding using a rough grindstone, and then grinding by using a fine grindstone. In this method, an oil groove having an appropriate depth is formed by smoothly finishing the surface of the bore.
In general, laser honing is performed by first forming a deep groove on the surface of the bore of the cylinder by laser processing, and then grinding and finishing the surface of the bore smoothly, so that an oil of an appropriate depth is obtained. This is a method of forming a groove. However, since laser honing is very expensive and the equipment cost is high, plateau honing is generally used.

Moreover, in patent document 3, it processes so that the surface of the bore | bore of a cylinder may become rough toward the bottom dead center side from the top dead center side of a piston, and a piston ring contacts as a piston moves toward a bottom dead center side. The amount of lubricating oil held in the bore is increased so that the piston reaches the bottom dead center while the piston ring smoothly slides on the cylinder bore.
JP-A-7-54707 Japanese Patent Laid-Open No. 11-236851 JP-A-8-200135

In the technique described in Patent Document 3, when processing the surface roughness of the cylinder bore to change in the sliding direction of the piston, the grindstone is pressed against the workpiece in order to change the surface roughness step by step. While changing the strength, the surface is ground by rotating and reciprocating simultaneously.
However, when changing the pressure of the grinding stone against the bore of the cylinder, there is a problem that a step occurs at the joint where the surface roughness changes, and the bore shape accuracy (internal diameter variation, cylindricity) deteriorates. Is likely to occur.
When the shape accuracy of the cylinder bore deteriorates, it is necessary to increase the tension of the piston ring in order to maintain the sealing performance of the combustion gas, and the friction between the piston ring and the bore increases, resulting in deterioration of fuel consumption and engine output performance. It will be.

  Therefore, the present invention proposes a method for processing an oil groove that can easily form an oil groove in an arbitrary portion of the bore while maintaining the shape accuracy of the cylinder bore.

  The problem to be solved by the present invention is as described above. Next, means for solving the problem will be described.

  That is, according to the first aspect of the present invention, the turning process is performed on the bore of the cylinder until the bore radius becomes a rough dimension that leaves the allowance for finishing grinding, and the oil groove forming portion of the bore is turned. In this cylinder bore oil groove machining method, a process of forming a deeper cut than the finish grinding allowance and a process of applying finish grinding to the entire surface of the bore and grinding only the finish grinding allowance are performed.

  According to claim 2, the turning conditions are set so that a notch formed in the bore by the turning tool used for the turning does not interfere with a notch formed at a position advanced by one revolution therefrom. Is to determine.

  As effects of the present invention, the following effects can be obtained.

  In claim 1, since the entire surface of the bore is sharpened under the same conditions (substantially constant pressing pressure of the grindstone) in the finishing process, good shape accuracy (cylindricity, inner diameter size) when machining the bore with coarse dimensions Accuracy and the like) can be maintained and improved. In addition, since it is possible to form an incision with an arbitrary incision amount at an arbitrary position in the bore, a bore with a surface property changed in the cylinder piston sliding direction while maintaining good shape accuracy of the bore is formed. It becomes possible to do. Furthermore, since the processing equipment can be configured at a low cost compared to laser honing, oil grooves can be easily and inexpensively formed in any part of the bore while maintaining the shape accuracy of the cylinder bore. Can do.

  In claim 2, by forming the incision by turning, it does not reduce the allowance for finish grinding, while maintaining and improving good shape accuracy when the bore is rough after finishing, An oil groove can be formed on the surface of the bore.

Next, embodiments of the invention will be described.
FIG. 1 is a flowchart showing an oil groove machining method according to an embodiment of the present invention, FIG. 2 is a sectional view showing a cylinder bore having a rough dimension, and FIG. 3 is a sectional view showing a cylinder bore after a cut is formed. FIG. 4 is a cross-sectional view for explaining the processing conditions of the cutting turning process, and FIG. 5 is a cross-sectional view showing the state of the cylinder bore after finish grinding.

  In the cylinder bore oil groove machining method of the present invention, in order to form an oil groove on the cylinder bore surface, turning (boring) is adopted as a roughing method, and grinding (honing) is adopted as a finishing method. It is characterized by doing.

Next, a method for processing an oil groove on the surface of the cylinder bore will be described with reference to the flowchart shown in FIG.
First, as shown in FIG. 2, machining is performed by turning (boring) until the diameter of the bore 10 of the cylinder 9 becomes the coarse dimension φ (S11).
In other words, in this process, the bore 10 of the cylinder 9 is turned until the coarse dimension φ with the finishing grinding allowance K remaining from the finished dimension. The coarse dimension φ of the bore 10 is determined in accordance with a cylinder piston (not shown). By this turning process, the shape (dimensions and cylindricity) and surface roughness of the bore 10 are adjusted to some extent, and the surface of the bore 10 processed to the rough dimension φ through the turning process is in a slightly rough state.

Subsequently, a cut 14 is formed on the surface of the bore 10 of the cylinder 9 by turning (boring) (S12).
.. Are formed in the bore 10 as shown in FIG. The depth of cut D applied to the surface of the bore 10 by the turning tool 20 is deeper than the finishing grinding allowance K, and deeper depths of the final finished surface of the bore 10 are formed. Become.
The cuts 14, 14... By turning are formed only in a portion of the bore 10 where the oil groove is provided (referred to as “rough surface portion 11”). The rough surface portion 11 is provided in a portion of the bore 10 of the cylinder 9 where an oil groove is required in order to improve lubricating oil retention. The other portion of the bore 10 of the cylinder 9 with respect to the rough surface portion 11 is a “smooth surface portion 12” whose surface roughness is fine and smooth.

The machining conditions for forming the incisions 14, 14... In the turning process are as follows. The cutting edge angle θ of the turning tool 20, the feed amount H per rotation of the turning tool 20, and the turning tool shown in FIG. 20 is set so as to satisfy the relationship of [(feed amount H per turning of the turning tool) ≧ 2 × (cut amount D) × tan (cutting edge angle θ / 2)]. .
By determining the machining conditions for turning as described above, the notch 14 at a certain position turned by the turning tool 20 does not interfere with the notch 14 formed at a position advanced by about one rotation therefrom. Positional relationship.
That is, the machining conditions are set so that the notches 14 and 14 formed on the surface of the bore 10 are not overlapped by the turning tool 20 used for turning.
In this way, by forming the incisions 14, 14... By turning, the finish grinding machining cost K of the bore 10 is not reduced. The shape is maintained and improved.

Finally, the surface of the bore 10 of the cylinder 9 is finish-ground (honed) (S13).
In this process, the final finishing process of the bore 10 of the cylinder 9 is performed, and the entire surface of the bore 10 is ground. In this grinding process, the grindstone is pressed against the surface of the bore 10 with substantially the same pressure, and the surface of the bore 10 is ground by the finishing grinding allowance K.
At this time, even if the finish grinding machining allowance K is cut in the bore 10, the cuts 14, 14... Formed by the turning process are deeper than the finish grinding allowance K, so that oil is applied to the surface of the bore 10. It remains as grooves 15.15. Therefore, as shown in FIG. 5, in the bore 10 subjected to finish grinding, oil grooves 15, 15... Are formed in the rough surface portion 11, and the smooth surface portion 12 has a smooth shape without irregularities.

In the above oil groove forming method, the cut 14 can be formed at a desired position of the bore 10 by turning, and the rough surface portion 11 and the smooth surface portion 12 are formed at the desired position of the bore 10 in the same cylinder 9. Can be formed.
In the above oil groove forming method, the entire surface of the bore 10 is sharpened under substantially the same conditions (substantially constant pressing force of the grindstone) in the finish grinding process, so that the bore when the bore 10 has a rough dimension φ 10 shape accuracy (cylindricity, inner diameter dimensional accuracy, etc.) can be maintained and improved.
Further, since the depth of the oil grooves 15, 15... Can be changed in the bore 10 of the same cylinder 9 by changing the cutting amount D by the turning tool 20, the load is low and lubricating oil is supplied. By roughening the surface roughness in the vicinity of the top dead center where the load is larger than in the vicinity of the bottom dead center where the cylinder piston is likely to be removed, it is possible to more effectively avoid metal contact and improve the retention of lubricating oil. Therefore, it may be possible to improve the seizure resistance more effectively. As described above, it is possible to form the bore 10 in which the surface properties are freely changed in any number in the cylinder piston sliding direction while maintaining the good shape accuracy of the bore 10.
Furthermore, in the oil groove forming method described above, since the equipment for processing can be configured at a lower cost compared to laser honing, any portion of the bore 10 can be maintained while maintaining the shape accuracy of the bore 10 of the cylinder 9. In addition, the oil groove 15 can be formed easily and inexpensively.

The flowchart which shows the oil groove processing method which concerns on the Example of this invention. Sectional drawing which shows the mode of the cylinder bore made into the rough dimension. Sectional drawing which shows the mode of the cylinder bore after forming a notch. Sectional drawing explaining the process conditions of a cutting turning process. Sectional drawing which shows the mode of the cylinder bore after finish grinding.

Explanation of symbols

10 bore 11 rough surface portion 12 smooth surface portion 14 notch 15 oil groove 20 turning tool

Claims (2)

The process of turning the bore of the cylinder until the bore radius becomes a rough dimension that leaves the allowance for finishing grinding, and
Turning the oil groove forming part of the bore to form a cut deeper than the finish grinding allowance,
The process of performing finish grinding on the entire surface of the bore and grinding for the amount of finish grinding.
An oil groove machining method for a cylinder bore, characterized by being implemented. The turning conditions are determined so that the notch formed in the bore with the turning tool used for the turning process does not interfere with the notch formed at the position advanced one revolution from there.
The cylinder bore oil groove machining method according to claim 1.

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