JP3170970B2 - Inner cylinder inner surface finishing method for workpiece - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for finishing an inner surface of an inner cylinder of a workpiece such as an inner surface of a cylinder block bore of an internal combustion engine.

[0002]

2. Description of the Related Art Conventionally, for example, when plateau processing is performed on the inner surface of a cylinder block bore of an internal combustion engine as the inner surface of an inner cylinder of a workpiece, for example, as shown in FIG.
After processing with a finishing whetstone like C220 # L,
For example, GC320 # J as shown in FIG.
In this case, two steps, such as performing plateau processing with a grinding wheel for plateau, were required. Also, for example, Japanese Utility Model Laid-Open No. 57-16
Japanese Patent Application Laid-Open No. 2054 discloses a dedicated plateau processing apparatus that simultaneously performs roughing, finishing, and plateau processing.

[0003]

By the way, of the above-mentioned prior art, if plateau processing is performed in two steps, the processing steps are complicated and the plateau processing requires a lot of time and labor. In addition, when using a dedicated plateau processing apparatus, a dedicated process is naturally required.

SUMMARY OF THE INVENTION An object of the present invention is to improve the above-mentioned problems by reducing the number of steps by obtaining a plateau surface in a single step without adding a dedicated step, thereby finishing the inner surface of an inner cylinder of a workpiece. It is to provide a method.

[0005]

In order to achieve the above object, a method for finishing the inner surface of an inner cylinder of a workpiece according to the present invention is provided on the outer periphery of the tip of a honing head (1) which is rotatable and reciprocally movable. The honing tool (3) is provided so as to be expandable outward, and a plurality of whetstones (5) provided at appropriate intervals around the circumference of the honing tool (3) to finish the inner surface of the inner cylinder of the workpiece. When performing, each of the grindstones is fixed with a soft binder, and is composed of a mixture of coarse abrasive grains for finishing and fine abrasive grains for plateau, and finishing the inner surface of an inner cylinder of a workpiece with the coarse abrasive grains. Performing the processing, the self-generation of coarse abrasive grains becomes active while performing the finishing processing, and after the coarse abrasive grains for finishing drop off, performing plateau processing with the fine abrasive grains for the plateau. Things.

[0006]

By using the method for finishing the inner surface of the inner cylinder of a workpiece according to the present invention, the honing head is rotated and reciprocated, so that the inner surface of the workpiece is formed by a grindstone provided on the outer peripheral portion of the tip of the honing head. The inner surface of the cylinder is finished.

[0007] Since each of the grindstones is composed of a mixture of coarse abrasive grains and fine abrasive grains fixed with a soft binder, first, the inner surface of the inner cylinder of the workpiece is finished with the coarse abrasive grains. During the finishing process, the self-generation of fine abrasive grains becomes active, and after the coarse abrasive grains for finishing fall off, plateau processing is performed with the fine abrasive grains for plateau.

[0008] Therefore, finishing and plateau processing are performed by one grindstone in which coarse abrasive grains and fine abrasive grains are mixed.

[0009]

An embodiment of the present invention will be described in detail with reference to the drawings.

Referring to FIG. 2, a front end portion (lower end portion) of a honing head 1 which is rotatable and vertically reciprocable.
Is provided with a honing tool 3. A plurality of grindstones 5 are provided on the outer peripheral portion of the honing tool 3 at appropriate intervals. In the honing tool 3, there is provided a known expansion device, for example, a conical tapered cone that applies a pressure for pressing the grindstone 5 against the inner surface of the bore B, that is, an expansion pressure.

With the above structure, a honing tool 3 provided at the tip of a rotatable and reciprocally movable honing head 1 is inserted into a bore B of a cylinder block CB in an internal combustion engine, for example, as an inner cylinder of a workpiece. Then, the honing head 1 is rotated and reciprocated vertically. Further, by applying a certain expansion pressure to the grindstone 5, the inner surface of the bore B of the cylinder block CB is honed by the grindstone 3.

As shown in FIG. 1, the grinding stone 5 is composed of a soft binder J and a mixture of, for example, 220 # coarse abrasive grains 5A and 320 # fine abrasive grains 5B, for example. I have.

FIG. 3 shows the definition of the hardness of the binder.
As shown in JIS, it is classified into 26 types from A to Z according to JIS “Vitrified grinding wheel” R6210-1986. It is defined that A is the softest and Z is the hardest. Therefore, the binder J is soft and belongs to the binder. Further, there is a relationship between the grain size of the grindstone and the hardness of the binder as shown in FIG. That is, in order to obtain a good plateau surface and to obtain the grinding efficiency, the range shown by the double diagonal lines in FIG. 4 is good. Therefore, with the binder J, the 220 # coarse abrasive grains 5A and the 320 # fine abrasive grains are used. Abrasive 5
A grindstone in which B is mixed is used.

With the above configuration, the inner surface of the bore B of the cylinder block CB is finished in the state of the grindstone 5 as shown in FIG.
The state of the surface is as shown in FIG. Further, as the finishing process is continued, the coarse abrasive grains 5A drop off more actively, and the surface of the grindstone 5 is in a state as shown in FIG. Finishing is performed in the surface state of the grindstone 5. That is, by finishing the inner surface of the bore B with the fine abrasive grains 5B, the inner surface of the bore B is plateau-processed as shown in FIG. 6B.

By fixing the coarse abrasive grains 5A and the fine abrasive grains 5B in a mixed state with a soft binder J, it is possible to finish the workpiece with a low expansion pressure,
Since the self-generation of A becomes active, a plateau surface is formed by the fine abrasive grains 5B. In addition, this coarse abrasive 5
For example, 220 # of A and 320 # of fine abrasive 5B
Is as shown in FIG. 7, for example.

Therefore, the coarse abrasive 5A and the fine abrasive 5
With one grindstone 5 in which B is mixed, finish processing and plateau processing can be performed on the inner surface of the bore B of the cylinder block CB, and a uniform plateau surface can be obtained. That is, since processing can be performed in one process using one grindstone 3 without adding a dedicated process, the number of processes can be reduced and the processing time can be reduced.

As shown in FIG. 8, for example, the grindstone 5 stirs a bond K serving as a soft binder, coarse abrasive grains (220 #) 5A, and fine abrasive grains (320 #) 5B. After mixing, press working and drying are performed. Further, a hardness test is performed by performing forming, sintering, and shaping. Then, after performing cutting and shape processing, acid treatment, water washing, through the drying process, the final inspection is performed,
The grinding stone 3 in which the coarse abrasive grains 5A and the fine abrasive grains 5B are mixed can be obtained.

The present invention is not limited to the above-described embodiment, but can be embodied in other modes by making appropriate changes. In this embodiment, 220 # is used as coarse abrasive 5A and 32 # as fine abrasive 5B.
Although 0 # is described as an example, the combination of the coarse abrasive grains 5A and the fine abrasive grains 5B can be appropriately changed depending on the workpiece and the desired surface properties.

[0019]

As will be understood from the above description of the embodiments, according to the present invention, since the structure is as described in the claims, coarse abrasive particles and fine abrasive particles By using a honing head with mixed grinding wheels, the inner surface of the inner cylinder of the workpiece can be made a plateau surface in one process without adding a dedicated process, which can reduce the number of processes and reduce the processing time Can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing a surface state of a grindstone provided at a tip of a honing head.

FIG. 2 is an explanatory view of performing finish processing of an inner surface of a bore of a cylinder block with a honing head.

FIG. 3 is an explanatory diagram showing types of hardness of a binder.

FIG. 4 is an explanatory diagram showing the relationship between the grain size of a grindstone and the hardness of a binder.

FIG. 5 is a diagram showing a state of a grindstone and a state of a processed surface when finishing is performed with coarse abrasive grains.

FIG. 6 is a diagram showing a state of a grindstone and a state of a processed surface when finishing is performed with fine abrasive grains.

FIG. 7 is a diagram showing a density distribution between coarse abrasive grains and fine abrasive grains.

FIG. 8 is an example of a process of obtaining a grindstone by mixing coarse abrasive grains, fine abrasive grains, and a bond.

FIG. 9 is a diagram showing an example of a finishing whetstone used for conventional plateau processing and a whetstone for plateau.

[Explanation of symbols]

 1 Honing Head 3 Honing Tool 5 Grinding Stone 5A Coarse Abrasive 5B Fine Abrasive CB Cylinder Block B Bore J Soft Binder L Hard Binder

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B24B 33/02 B24B 33/08

Claims (1)

(57) [Claims] A honing head (1) rotatably and reciprocally movable is provided on a honing tool (3) provided on an outer peripheral portion of a distal end of the honing head (1) so as to be expandable outward, and is appropriately provided on a circumference of the honing tool (3). When finishing the inner surface of the inner cylinder of the workpiece with a plurality of grindstones (5) provided at various intervals, each of the grindstones is fixed with a soft binder, but coarse abrasive grains for finishing and fine abrasive for plateau are used. The surface of the inner cylinder of the workpiece is subjected to finish processing with the coarse abrasive grains, and during the finish processing, the self-generation of the coarse abrasive grains becomes active, and the rough A method for finishing the inner surface of an inner cylinder of a workpiece, wherein plateau processing is performed with fine abrasive particles for the plateau after the abrasive particles fall off.