JPH0531664A - Honing processing method - Google Patents

Abstract

PURPOSE:To prevent the occurrence of poor cylindrical roundness on the inner surface of a cylinder by providing a necessary enough grinding work amount even when overrun of a grinding wheel is limited. CONSTITUTION:Through detection of the position of a reciprocating honing head 1, the expansion pressure of a grinding wheel 3 is varied and controlled according to the position of the honing head 1. In a process wherein the honing head 1 is lowered from the upward limit position toward the downward limit position, the expansion pressure of the grinding wheel 3 is gradually increased and control is effected such that the grinding wheel expansion pressure in the downward limit position of the honing head 1 is maximized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a honing method for an inner surface of a cylinder.

[0002]

2. Description of the Related Art In performing honing on an inner surface of a cylinder represented by, for example, a bore portion of a cylinder block, an overrun b is applied to a stroke S1 of a grindstone 32 mounted on a honing head 31 as shown in FIG. The grinding stone 3 is included from the upper and lower end portions of the inner surface 33 of the cylinder which is the processing surface
It is general to process while projecting a part of 2.
This is to make the contact between the whetstone 32 and the inner surface 33 of the cylinder uniform and to make the wear of the whetstone 32 uniform, and at the same time, to make the inner surface 33 of the cylinder 33 uniform.
Is to prevent the taper from becoming tapered and to improve the cylindricity of the inner surface 33 of the cylinder.

[0003]

However, depending on the shape of the workpiece W to be honed, the above-mentioned overrun b may not be sufficiently secured. For example, when one end of the cylinder inner surface 33 is closed by the cylinder block, such as the cylinder bore portion of a cylinder block integrated with a cylinder head, the honing head 31 is inserted from the crankshaft side end of the cylinder bore portion to perform the honing process. Will be done. In this case, the above-mentioned overrun b cannot be secured on the one end side of the cylinder inner surface 33 of the cylinder bore part because the cylinder head part becomes an obstacle during the honing process.
It will be very small if it can be secured.

Therefore, if honing is performed in this state, the diameter of the end portion of the cylinder inner surface 33 on the cylinder head side is smaller than the diameter of the other end portion, and the entire cylindrical surface is tapered, resulting in the machining. It cannot be expected to improve the accuracy of the cylindricity of the surface.

The present invention has been made in view of the above problems, and an object thereof is to provide a predetermined cylinder even when it is not possible to sufficiently secure the overrun of the grindstone due to the restriction of the work shape. It is to provide a honing processing method capable of maintaining a high degree.

[0006]

DISCLOSURE OF THE INVENTION The present invention is a method for honing a cylindrical inner surface by hydraulically applying an expanding pressure to a grindstone of a honing head. The feature is that the position of the head is detected and the expansion pressure of the grindstone is changed according to the position of the honing head.

[0007]

According to this method, in the example of the cylinder block integrated with the cylinder head, for example, when the grindstone of the honing head is located at the end on the cylinder head side where the overrun of the grindstone is restricted, the expansion pressure Is larger than the expansion pressure on the other end side. As a result, the same amount of grinding work as in the case where a necessary and sufficient overrun is secured can be obtained, and a predetermined cylindricity can be maintained without the cylinder bore portion becoming tapered.

[0008]

1 and 2 show an embodiment of the present invention. As shown in FIG. 1A, the honing head 1
Is equipped with a plurality of grindstones 3 mounted on the grindstone holder 2. The grindstones 3 are pressed against the inner surface 4 of the cylinder, and the honing head 1 moves along the axial center of the inner surface 4 of the cylinder while rotating. Honing is performed by reciprocating with and. However, in the example of FIG. 1A, the grindstone 3 on the upper end side of the inner surface 4 of the cylinder is restricted due to the restriction on the shape of the work W.
It is assumed that the overrun e on the lower end side is restricted to be significantly smaller than the overrun E of.

The reciprocating motion of the honing head 1 is given by the hydraulic cylinder 16 shown in FIG. 2, and the switching valve 6 is switched in response to an instruction from the control device 5 so that the forward and backward movements thereof are controlled to be switched, and the honing is performed. The head 1 is rotationally driven by a motor (not shown) via a gear train 7. The current position of the grindstone 3 mounted on the honing head 1 is detected by a position detector 9 having a detection rod 8, and the position information is taken into the control device 5.

The expansion pressure of the grindstone 3 for pressing the grindstone 3 against the inner surface 4 of the cylinder is given by an expansion cylinder (hydraulic cylinder) 10. Piston rod 1 of expansion cylinder 10
As shown in FIG. 1, a taper cone 12 is attached to the tip of the taper 1. The taper cone 12 is in sliding contact with the taper surface 13 of the grindstone holder 2. Therefore, the expansion cylinder 10
By pushing the tapered cone 12 into the grindstone holder 2, the grindstone 3 is expanded and pressed against the inner surface 4 of the cylinder.
Reference numeral 15 is a hydraulic power source.

Further, the expansion pressure of the grindstone 3 can be arbitrarily adjusted even during machining, and as shown in FIG. 2, the controller 5 controls the set pressure of the secondary pressure variable pressure reducing valve 14.
The hydraulic pressure introduced into the expansion cylinder 10 and thus the expansion pressure of the grindstone 3 is variably controlled by adjusting the pressure according to the instruction from.

In this embodiment, the grindstone 3 is used as described above.
By detecting the current position of the
(B), the expansion pressure of the grindstone 3 is proportionally increased in the process of the grindstone 3 making a stroke from the ascending limit position toward the descending limit position. On the contrary, in the process in which the grindstone 3 rises from the lower limit position to the upper limit position, the expansion pressure of the grindstone 3 is proportionally reduced. As a result, the change in expansion pressure when the reciprocating motion of the honing head 1 is repeated is shown in FIG.
As shown in the lower half of (B), the expansion pressure becomes maximum at the lower limit position of the grindstone 3 and becomes minimum at the upper limit position.

By changing the expanding pressure of the grindstone 3 in accordance with the stroke position of the grindstone 3 in this manner, as shown in FIG.
Even when the overrun e on the lower end side of the inner surface 4 of the cylinder is limited to a significantly small one as shown in (4), the same amount of grinding work as in the case of ensuring the necessary and sufficient overrun to increase the expansion pressure is obtained Be done. Therefore, it is possible to maintain a predetermined cylindricity without reducing the diameter of the lower end portion side of the inner surface 4 of the cylinder due to lack of the overrun e.

FIG. 3 is a view showing another embodiment of the present invention. In this embodiment, the position where the expansion pressure should be increased or decreased in the middle of the stroke of the grindstone 3 is preset by the control device 5 side, The expansion pressure is stepwise increased or decreased when the grindstone 3 reaches the position. Also in the case of this embodiment, the same effect as that of the first embodiment can be obtained.

[0015]

As described above, according to the present invention, the position of the reciprocating honing head is detected, and the expansion pressure of the grindstone is variably controlled according to the position. Even if a sufficient overrun of the grindstone cannot be ensured due to the above restriction, a necessary and sufficient amount of grinding work can be obtained without being affected by the overrun in terms of grinding performance. Therefore, the inner surface of the cylinder is not tapered, and the predetermined cylindricity accuracy can be maintained, and the processing quality is improved.

[Brief description of drawings]

FIG. 1 is a view showing an embodiment of the present invention, (A) is an enlarged cross-sectional view of a honing head during processing, and (B) is an explanatory view showing a relationship between a stroke of the honing head and a grindstone expanding pressure. ..

FIG. 2 is a structural explanatory view of a drive system of a honing device including the honing head of FIG.

FIG. 3 is a view showing another embodiment of the present invention, and an explanatory view showing changes in the grindstone expansion pressure.

FIG. 4 is an explanatory view showing an example of a conventional honing method.

[Explanation of symbols]

 1 ... Honing head 2 ... Grinding stone holder 3 ... Grinding stone 4 ... Cylindrical inner surface 9 ... Position detector 10 ... Expansion cylinder 12 ... Tapered cone 14 ... Pressure reducing valve

Claims (1)

Claim: What is claimed is: 1. A method for honing a cylindrical inner surface by hydraulically applying an expanding pressure to a grindstone of a honing head, the method comprising: A honing method comprising detecting the position and changing the expanding pressure of the grindstone according to the position of the honing head.