JP2514710B2 - Honing processing method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a surface processing method for a workpiece made of an aluminum alloy having a high silicon (Si) content, and in particular, the surface of the workpiece is elastic. The present invention relates to a honing method for processing with a grindstone.

(Prior Art) For example, a cylinder of an automobile engine has heretofore been formed by forming a cylinder block of an aluminum alloy in order to reduce the weight of the engine and improve thermal conductivity, and by fitting a cylinder liner made of cast iron into the cylinder block. Was configured.

The inner wall surface of the workpiece such as the cylinder liner is processed by honing as is well known, and a honing tool having a honing head 5 is used as shown in FIG. In the body 6 of the honing head 5, a push rod 7 having a tapered cone 8 is provided so as to be movable in the axial direction. A stone holder 9 holding a rod-shaped grindstone 10 is provided on the outer periphery of the body 6 with its tapered surface 9a in contact with the tapered cone 8. Therefore, when the push rod 7 is pushed down by means of hydraulic pressure or the like, the stone holder 9 is moved outward by the taper cone 8, whereby the grindstone 10 is pressed and expanded against the inner wall surface 4 of the workpiece 1. It is supposed to be done. In addition, a drive motor (not shown) and a hydraulic device that reciprocates are connected to the body 6, and the honing head 5 is rotatable and reciprocally movable. Then, apply expansion pressure to the grindstone 10,
The inner wall surface 4 of the workpiece 1 is machined by reciprocating the honing head 5 in the axial direction while rotating.

As described above, the honing is performed by the rotary motion and the reciprocating motion of the grindstone 10, and the grinding speed is represented by the spindle speed V that is a combination of the circumferential speed Vr and the reciprocating speed Va. There is a close relationship between the spindle speed V and the grinding amount. When the spindle speed V is increased, the grinding amount increases, but when the speed exceeds a predetermined limit speed, the grinding amount decreases conversely. Further, the expansion pressure applied to the grindstone 10 is an important factor that affects the finishing surface and work efficiency, and when the expansion pressure is small, it is natural that the grinding amount is small and the work efficiency is poor, but the expansion pressure is increased. If it is too much, the force applied to the abrasive grains increases, so that the abrasion of the grindstone 10 remarkably increases, and the amount of grinding does not increase for that reason.

By the way, in the cylinder configured by fitting the cylinder liner into the cylinder block, there is a problem that when the cylinder liner is fitted, the adhesion between them is not good or deformation occurs. It was

Therefore, in recent years, without using a cylinder liner, the cylinder itself is manufactured from an aluminum alloy, thereby further reducing the weight of the engine and improving the thermal conductivity.

As an aluminum alloy used for this type of cylinder, as disclosed in JP-A-57-9900, a hypereutectic Al-Si alloy in which the silicon content is increased to about 16 to 18% by weight. It is known that the silicon particles are floated from the inner wall surface of the cylinder, the wear resistance is improved by the silicon particles, and the recesses between the lifted silicon particles ensure that the lubricating oil is retained.

Japanese Unexamined Patent Publication (Kokai) No. 52-147,392 proposes honing the inner wall surface of the cylinder made of the hypereutectic aluminum alloy with an elastic grindstone.

(Problems to be Solved by the Invention) However, under the conditions of the spindle speed V and the expanding pressure when honing a conventional cast iron cylinder liner, the inner wall surface of the cylinder made of a hypereutectic aluminum alloy is Honing processing with an elastic grindstone has a drawback in that processing defects such as crushing or falling off of silicon particles occur. In addition, the roundness of the inner wall surface of the cylinder has an allowable limit value of 6 μ or more as a product, and there is a problem that a high quality product cannot be manufactured.

In order to prevent such problems from occurring, it is possible to reduce the processing efficiency and perform honing processing, but reducing the processing efficiency is against the mission of improving the series production efficiency of automobile parts. Therefore, the processing efficiency cannot be reduced effectively.

Therefore, as a result of diligent efforts to eliminate such drawbacks, the present inventors have performed honing processing capable of producing a high-quality product without causing processing defects such as crushing of silicon particles and improving production efficiency. I came to find a way.

The present invention has been made in view of the above problems of the prior art, in performing the honing process of the surface of the workpiece made of a hypereutectic aluminum alloy by an elastic grindstone, while improving the production efficiency An object of the present invention is to provide a honing processing method capable of finishing with high quality without causing defects.

(Means for Solving the Problems) The present invention for achieving the above-mentioned object, in processing a surface of a workpiece made of a hypereutectic aluminum alloy,
A honing method for processing the surface by rotating and reciprocating the elastic grindstone while expanding the elastic grindstone toward the surface side, wherein a pressure for expanding the elastic grindstone is 3 to 8k.
The surface of the workpiece made of the hypereutectic aluminum alloy is processed in the range of gf / cm2, and the spindle speed obtained by combining the rotational speed and the reciprocating speed in the range of 47.0 to 100 m / min. It is a honing method.

(Operation) The hypereutectic crystal is formed by setting the pressure for expanding the elastic grindstone in the range of 3 to 8 kgf / cm2, and the main spindle speed in which the speed of the rotary motion and the speed of the reciprocating motion are combined to the range of 47.0 to 100 m / min. Honing the surface of the workpiece made of an aluminum alloy improves the production efficiency, and the surface of the workpiece can be processed without causing processing defects such as crushing and falling out of the precipitated silicon particles.

(Example) Hereinafter, a honing method according to the present invention will be described based on an example of machining an inner wall surface of a cylinder including this method.

FIG. 1 is a graph showing the relationship between expansion pressure and grinding amount according to the honing processing method of the present invention, and FIG. 2 is a graph showing the relationship between expansion pressure and roundness according to the honing processing method of the present invention. FIG. 3 is a process drawing of the inner wall surface of the cylinder, FIG. 4 is a cross-sectional view showing the inner wall surface of the cylinder at each stage of the working process, and FIGS. 5 to 6 are honing heads used in honing. FIG.

First, the inner wall surface processing step of a cylinder made of a hypereutectic Al-Si alloy will be outlined with reference to FIG. As shown in the figure, the machining process consists of six steps, and the cylinder 1 after casting as the work piece is in a state where a large number of silicon particles 3 are deposited inside the aluminum base material 2 as shown in FIG. is there.

In the first step, rough boring is performed by the cutting means up to line A in FIG.

In the second step, cutting is performed with higher accuracy than in the previous step, and fine boring is performed up to line B in the figure.

In the third step, the inner wall surface 4 of the cylinder 1 is ground by the honing method according to the present invention. This process consists of two steps. First, a semi-honing process is performed by a roughing grindstone, and grinding is performed up to C line. Next, finish honing is performed with a finishing grindstone, and the D line is ground. In addition, in this step, the silicon particles 3
The above-mentioned elastic grindstone is used as the grindstone so that the silicon particles 3 are not crushed by collision with the abrasive grains. And, as is clear from the experimental results shown below, the expansion pressure is in the range of 3 to 8 kgf / cm2, and the spindle speed is
It was found that the practical processing conditions are those under the conditions of 47.0 to 100 m / min.

In the fourth step, the cylinder 1 is washed. This is to remove the working fluid (coolant) remaining on the inner wall surface 4 of the cylinder 1 in the third step.

In the fifth step, the aluminum base material 2 on the inner wall surface 4 of the cylinder 1 is etched. That is, electrolytic etching or chemical etching is performed to dissolve only the aluminum base material 2 up to the line E in the figure, and the silicon particles 3
(See Japanese Patent Publication No. 62-25,754, etc.). The height of protrusion of the processed silicon particles 3 from the surface of the aluminum base material 2 is about 1 μm.

Then, in the sixth step, if cleaning is performed to remove the etching treatment liquid remaining in the cylinder 1, the surface processing of the cylinder is completed.

Next, the honing head 5 used in the third step will be described with reference to FIGS. This honing head 5 is a roughing grindstone 17 for semi-honing.
And a finishing grindstone 18 for finishing honing are selectively expandable under pressure, and a hollow top joint 11 is fixed to a top portion of a body 6 as a main body by a bolt 12. In the through hole of the top joint 11, a coarse push rod 13 that is movable in the axial direction is mounted, and a finishing push rod 14 is provided inside the rough push rod 13 so as to be movable in the axial direction. . A taper surface is provided at the end of the rough push rod 13.
Coarse taper cone 15 with 15a formed is connected, and finishing push rod 14 also has tapered surface 16
A finishing taper cone 16 having a formed therein is attached. On the outer circumference of the body 6, a rough stone holder 19 holding a rod-shaped rough grinding stone 17 is provided with a taper surface 19 thereof.
The a is attached in a state of abutting on the tapered surface 15a of the rough taper cone 15. On the other hand, the finishing stone holder 20 holding the finishing grindstone 18 is also mounted with its tapered surface 20a in contact with the tapered surface 16a of the finishing tapered cone 16. Both these stone holders 1
As shown in FIG. 6, 9 and 20 are mounted on concentric circles at regular intervals, respectively. Further, in order to tighten the roughening grindstone 17 in the axial direction of the body 6, the spring 21 for urging the elastic force in the direction of pulling up the roughening taper cone 15 upward in the drawing has the top joint 21 and the roughening taper. It is mounted between the cone 15 and. Further, in order to move the rough stone holder 19 along with the pulling movement of the rough taper cone 15, a return pin 23 to be inserted into the hole 25 of the holder 19 is fixed to the rough taper cone 15. . Similarly, in order to tighten the finishing grindstone 18 in the axial direction of the body 6, a spring 22 for urging an elastic force in a direction of pressing the finishing taper cone 16 upward is mounted between the body 6 and the spring 22. ing. A return pin 24 inserted into the hole 26 of the holder 20 is fixed to the finishing taper cone 16. A pressure device (not shown) that selectively pushes down the rods 13 and 14 by hydraulic pressure or the like is connected to the push rods 13 and 14. Further, a drive motor for performing a rotational movement and a hydraulic device for performing a reciprocating movement are connected to the body 6, so that the honing head 5 can rotate and reciprocate.

Then, when the roughing push rod 13 is pushed down by the pressurizing device, the roughening taper cone 15 is pushed down, and both the upper and lower tapered surfaces 15 of the roughening stone holder 19 are pressed.
Abutting on both the upper and lower tapered surfaces 19a of the holder 19
Will be moved evenly outward. Therefore, the roughing grindstone 17 also projects outward and is pressed against the inner wall surface 4 of the cylinder 1. Further, by controlling the amount of depression of the rough push rod 13, it is possible to control the pressure contact force of the rough grinding stone 17, that is, the expansion pressure, and the semi-honing process is performed under a predetermined expansion pressure. It will be.

Similarly, by controlling the amount by which the finishing push rod 14 is pushed down, the expansion pressure of the finishing grindstone 18 is controlled,
The finish honing process is performed under this predetermined expansion pressure.

In the honing process using the elastic grindstone, the relationship between the expansion pressure and the spindle speed, the processing efficiency and the product accuracy will be described based on the test effect.

The material of the cylinder used for the test is the above-described hypereutectic aluminum alloy, and the conditions of expansion pressure and spindle speed are as shown below.

Expansion pressure (kgf / cm2) 3 to 9 Spindle speed (m / min) 23.5 47.0 85.5 First, under this condition, a test was conducted on the relationship with the grinding amount by honing. The test results are shown in FIG.

As is clear from the figure, the slowest spindle speed is 23.5 m /
In case of min, the grinding amount increases as the expansion pressure increases,
It can be seen that the processing efficiency is improved.

When the spindle speed is 47.0 m / min, the grinding amount gradually increases as the expanding pressure is increased, and the machining efficiency is remarkably improved when the expanding pressure is 6 kgf / cm2 or more.

When the main spindle speed is 85.5m / min, the expansion pressure is 6kgf /
It can be seen that the grinding amount only slightly increases up to cm2, but when the expansion pressure is 6 kgf / cm2 or more, the grinding amount sharply increases and the machining efficiency is remarkably improved.

Next, the accuracy of the product obtained under the above conditions was inspected. As the product accuracy, the roundness of the inner wall surface of the cylinder is adopted, and the inspection result is shown in FIG. The circularity that is practically acceptable as a cylinder product is 6μ or less,
A more preferable roundness is 5 μm or less.

As is clear from the figure, the slowest spindle speed is 23.5 m /
In the case of min, the circularity tends to deteriorate as the expansion pressure is increased in the range of the expansion pressure of 3 to 6 kgf / cm2, and the circularity is increased as the expansion pressure is increased in the range of the expansion pressure of 6 to 9 kgf / cm2. Tends to get better. However, at this spindle speed, even if the expansion pressure is about 3 to about 8 kgf / cm2, the roundness is worse than the practical allowable value of 6μ, and the machined cylinder 1 is suitable for products. You can see that not.

When the spindle speed is 47.0 m / min, the circularity gradually deteriorates as the expanding pressure increases, and it tends to deteriorate when the expanding pressure is 6 kgf / cm2 or more. However, when the expansion pressure is about 8 kgf / cm2 or more, the roundness is worse than the practical allowable value of 6μ, and it can be seen that the machined cylinder 1 is not suitable for a product. Further, it becomes clear that it is desirable to set the expansion pressure to 7 kgf / cm 2 or less in order to increase the more preferable circularity, that is, the circularity higher than 5 μ.

At the highest spindle speed of 85.5 m / min, even if the expansion pressure is increased, there is almost no change up to 6 kgf / cm2. Expansion pressure is 6kgf / c
The roundness gradually deteriorates as the m2 or more, but
In the range of the expanded pressure tested, the roundness is less than the practical allowable value of 6 μ, which means that the machined cylinder 1 is suitable for the product.

Therefore, considering practical circularity from Figs. 1 and 2, when the expansion pressure is 8 kgf / cm2 or more, and the spindle speed V
Is 23.5 m / min, the roundness is practically 6 μm.
It may worsen, while the spindle speed V is 47.0〜
If it is in the range of 85.5 m / min, the processing efficiency will not be reduced. From the experimental results not shown in FIGS. 1 and 2, the spindle speed was 30.0 m / m from the viewpoint of machining efficiency.
It had to be set to min or higher. However, if the spindle speed is increased too much, the machining efficiency is not improved for the wear of the grindstone, and it is not practical.

That is, when honing a cylinder made of a hypereutectic aluminum alloy with an elastic grindstone, an expansion pressure of 3 to
Within the range of 8 kgf / cm2, and the spindle speed V is 47.0 to 100 m / m
It has been clarified that if the processing is performed within the range of in, a high quality product that can be practically used can be obtained while improving the processing efficiency.

However, considering a more preferable circularity of 5μ, the expansion pressure is set in the range of 5 to 7 kgf / cm2, and the spindle speed V is set to 47.0 to
It is desirable to process in the range of 85.5m / min.

(Effects of the Invention) As described above, according to the present invention, the pressure for expanding the elastic grindstone is set in the range of 3 to 8 kgf / cm 2, and the spindle speed obtained by combining the rotational speed and the reciprocating speed is 47.0 to. 100m
Since it is a honing processing method for processing the surface of a workpiece made of a hypereutectic aluminum alloy as a range of / min,
It is possible to obtain a practically great effect that the silicon particles deposited on the aluminum base material can be processed without crushing and dropping off and the production efficiency can be improved.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between expansion pressure and grinding amount according to the honing processing method of the present invention, and FIG. 2 is a graph showing the relationship between expansion pressure and roundness according to the honing processing method of the present invention. Fig. 3 is a process drawing of the inner wall surface machining of the cylinder, No. 4
FIG. 5 is a cross-sectional view showing the state of the inner wall surface of the cylinder at each stage of the working process, FIG. 5 is a cross-sectional view showing the honing head used in the honing process, and FIG. 6 is shown in FIG.
FIG. 7 is a sectional view taken along the line VI-VI, and FIG. 7 is a schematic sectional view of the honing head used for explaining the honing process. 1 ... Cylinder (workpiece), 2 ... Aluminum base material, 3 ... Silicon particles, 5 ... Honing head, 17 ... Coarse grinding wheel (elastic grindstone), 18 ... Finishing grindstone (elastic grindstone) .

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masahiko Iizumi 2 Takara-cho, Kanagawa-ku, Kanagawa Prefecture Nissan Motor Co., Ltd. (72) Inventor Atsushi Hirose 2 Takara-cho, Kanagawa-ku, Yokohama Kanagawa Prefecture Nissan Motor Co., Ltd. (56) References JP-A-63-295172 (JP, A) Actually developed S63-28989 (JP, U)

Claims (1)

(57) [Claims] 1. A honing method for processing a surface of a work piece made of a hypereutectic aluminum alloy, wherein the elastic grindstone is expanded toward the surface side and is rotated and reciprocally moved to process the surface. The pressure for expanding the elastic whetstone is in the range of 3 to 8 kgf / cm2, and
A honing method, comprising: processing a surface of a workpiece made of the hypereutectic aluminum alloy with a spindle speed obtained by combining the rotational speed and the reciprocating speed being in the range of 47.0 to 100 m / min.